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JP2011236916

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DESCRIPTION JP2011236916
A device for performing thermodynamic work on fluids, such as a pump (340), a compressor and
a fan. Thermodynamic work can be used to provide a motive force to move a fluid. The work
done on the fluid may be transmitted to other devices such as pistons in the hydraulic drive
device. The device may include one or more electroactive polymer transducers (341) with an
electroactive polymer (341) that flexes in response to the application of an electric field.
Electroactive polymers (341) may be used to perform thermodynamic work on the fluid. The
device may be designed to operate efficiently at multiple operating conditions, such as operating
conditions that produce acoustic signals above or below human hearing. The device may be used
in thermal control systems such as refrigeration systems, cooling systems and heating systems.
[Selected figure] Fig. 3J
Electroactive polymer device for moving fluid
[0001]
Cross-reference to related applications
[0002]
This application is directed to Pelrine, et al., Entitled Electroactive Polymer Devices For Moving
Fluid.
Claims the priority of co-pending US Provisional Patent Application No. 60 / 365,472 filed Mar.
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18, 2002, under 35 USC 119 119 (e), which application is for all purposes Hereby incorporated
by reference.
[0003]
This application is a continuation-in-part of co-pending US patent application Ser. No. 09 /
792,431, filed Feb. 23, 2001, entitled Electroactive Polymer Thermal Electric Generators, and
claims priority to all of which is incorporated herein by reference. The application is incorporated
herein by reference for the purpose of Q. Pei et al., Entitled ELECTROE LASTOMERS AND THEIR
USE FOR POWER GENERATION. Claiming priority under 35 USC 119 119 (e) to US Provisional
Patent Application No. 60 / 184,217 filed Feb. 23, 2000, the inventor of which is hereby
incorporated by reference for all purposes The application, which is hereby incorporated by
reference, is also described in JS Eckerle et al., Entitled ARTIFICIAL MUSCLE GENERATOR.
Claiming priority under 35 USC 119 119 (e) to US Provisional Patent Application No. 60 /
190,713 filed March 17, 2000, the inventor of which is for all purposes Hereby incorporated by
reference.
[0004]
This application is a continuation-in-part of co-pending US patent application Ser. No. 10 /
154,449, filed May 21, 2002, entitled Rolled Electroactive Polymers, and claims priority, which
application is for all purposes. No. 60 / 293,003, filed on May 22, 2001, claiming priority under
35 USC 119 119 (e), which is hereby incorporated by reference for This application is hereby
incorporated by reference for all purposes.
[0005]
This application is a continuation-in-part of co-pending US patent application Ser. No. 10 /
553,511, filed Jan. 16, 2002, entitled Variable Stiffness Electroactive Polymer Systems, claiming
priority, all of which are incorporated herein by reference. No. 60 / 293,005, filed May 22, 2001,
which claims priority under 35 USC 119 119 (e), which is hereby incorporated by reference for
the purpose of This application is hereby incorporated by reference for all purposes, said
application claims priority of US Provisional Patent Application No. 60 / 327,846 entitled
Enhanced Multifunctional Footwear 35 USC 119 119 (e) As claimed below, this application is
hereby incorporated by reference for all purposes.
[0006]
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2
This application is a continuation-in-part of co-pending US patent application Ser. No. 09 /
619,847, filed Jul. 20, 2000, entitled "Improved Electroactive Polymers", which claims priority
and which application is for all purposes. No. 11 / 118,075, which application is hereby
incorporated by reference in its entirety, which is hereby incorporated by reference in its entirety
to RE Pelrine et al.
Claiming priority under 35 USC 119 119 (e) to US Provisional Patent Application No. 60 /
144,556 filed July 20, 1999, the inventor of which is hereby incorporated by reference for all
purposes. The application, which is incorporated herein by reference, is described in RE Pelrine
et al., Entitled Electrostrictive Polymers As Microactuators.
Claiming priority under 35 USC 119 119 (e) to US Provisional Patent Application Ser. No. 60 /
153,329 filed on Sep. 10, 1999, the inventor of which is hereby incorporated by reference for all
purposes. The application, which is hereby incorporated by reference, is described in RE Pelrine
et al., Entitled Artificial Muscle Microactuators. Claiming priority under 35 USC 119 119 (e) to
US Provisional Patent Application No. 60 / 161,325 filed October 25, 1999, the inventor of
which is hereby incorporated by reference for all purposes The application, which is
incorporated herein by reference, is described in RD Kornbluh et al., Entitled Field Actuated
Elastomeric Polymers. Claiming priority under 35 USC 119 119 (e) of US Provisional Patent
Application No. 60 / 181,404 filed Feb. 9, 2000, the inventor of which is for all purposes The
application, which is incorporated herein by reference, is described in RE Pelrine et al., Entitled
Polymer Actuators and Materials. Claiming priority under 35 USC 119 119 (e) to US Provisional
Patent Application No. 60 / 187,809, filed March 8, 2000, the inventor of which is for all
purposes The application, which is hereby incorporated by reference, is described in RD
Kornbluh et al., Entitled Polymer Actuators and Materials II. Claiming priority under 35 USC 119
119 (e) to US Provisional Patent Application No. 60 / 192,237 filed Mar. 27, 2000, the inventor
of which is for all purposes The application, which is incorporated herein by reference, is
described in RE Pelrine et al., Entitled Electroelastomers and their use for Power Generation.
Claiming priority under 35 USC 119 119 (e) of US Provisional Patent Application No. 60 /
184,217 filed Feb. 23, 2000, the inventor of Hereby incorporated by reference.
[0007]
This application is a continuation-in-part of co-pending US patent application Ser. No. 10 /
007,705, filed Dec. 6, 2001, entitled Electroactive Polymer Sensors, which application is filed on
May 22, 2001. Priority is claimed to US Provisional Patent Application No. 60 / 293,004 filed
under 35 USC 119 119 (e), which is hereby incorporated by reference for all purposes and which
is hereby incorporated by reference. Priority is claimed from US Provisional Patent Application
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No. 60 / 194,817, filed April 5, 2012, all of which applications are hereby incorporated by
reference for all purposes.
[0008]
This application is a continuation-in-part of co-pending US patent application Ser. No. 10 /
066,407, filed Jan. 31, 2002, entitled Devices and Methods for Controlling Fluid Flow Using
Elastic Sheet Deflection, and claims priority. This application is hereby incorporated by reference
for all purposes.
[0009]
This application is a continuation-in-part of co-pending US patent application Ser. No. 09 /
779,203, filed Feb. 7, 2001, entitled Monolithic Electroactive Polymers, and claims priority to
The priority of Provisional Application No. 60 / 181,404 is claimed under 35 USC 119 119 (e),
which is hereby incorporated by reference for all purposes.
[0010]
This application is directed to Heim, et al.
No. 10 / 090,430, filed on Feb. 28, 2002, entitled Electroactive Polymer Rotary Motors, filed on
Feb. 28, 2002, which application is entitled "Electroactive Polymer Motors," 2001. Priority is
claimed to US Provisional Patent Application No. 60 / 273,108, filed March 2, 2012 under 35
USC 119 119 (e), which applications are hereby incorporated by reference for all purposes. Ru.
[0011]
This application is related to co-pending US patent application Ser. No. 10 /, filed March 5, 2003
by Heim et al. Entitled Electroactive Polymer Devices for Controlling Fluid Flow, which is
incorporated by reference in its entirety for all purposes. Incorporated herein by reference.
[0012]
The present invention relates generally to electroactive polymer devices that convert between
electrical energy and mechanical energy.
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More specifically, the invention relates to a pump device comprising one or more electroactive
polymer transducers.
[0013]
Fluid systems are widespread.
The automotive industry, the piping industry, the chemical process industry, the computer
industry, the refrigeration / cooling industry, the household appliances industry, and the
aerospace industry are some of the examples where fluid systems are so important.
In most fluid systems, it is often desirable to perform thermodynamic work on the fluid in the
fluid system. Thermodynamic work, as in the case of a pump or fan, can be used to provide the
energy needed to move fluid in a fluid system from one position to another in the fluid system.
As another example, thermodynamic work may be like compressing the fluid in the refrigeration
system from gas phase to liquid, or compressing the fluid in the combustion system prior to
combustion, as in an automobile engine , May be used to place the fluid in the desired
thermodynamic state. As yet another example, thermodynamic work may be performed on the
energy fluid as a means of energy conversion, such as a hydraulic lift or hydraulic control
system.
[0014]
In general, pumps, fans and compressors have a wide range of applications, both household and
industrial. As an example, pumps, fans and / or compressors circulate the refrigerant in cooling
systems (eg air conditioners, refrigeration), remove waste heat, discharge water in cleaning
equipment and automatic dishwashers, in the computer industry Removing waste heat from a
heat source (e.g. CPU), pressurizing air for a pneumatic system, transporting water for irrigation,
transporting oil and gas in pipelines, and chemical process plant Used to move fluid between
various unit operations within. Pumps and compressors are also widely used in medical
applications, for example, for dialysis or for circulating blood during surgical treatment.
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[0015]
Pumps, fans and compressors have been around for centuries to perform thermodynamic work
on fluids. Conventional pumps and compressors are mainly piston driven by electric motors, and
these conventional devices are heavy (bulky), noisy and inefficient at low speeds (or step down
the gearbox to step down high speeds) It may be necessary), mechanically complicated and
expensive. Electric motors are generally designed to operate in the range of 50-500 Hz. These
motors usually operate in the audible range and need to be geared down (with cost, weight,
inefficiency, and complexity) to the proper pump or compressor frequency. There is a need for
lighter weight, higher power, and more efficient, quieter, lower cost pumps, fans, compressors,
and hydraulics for many applications.
[0016]
New high performance polymers capable of converting electrical energy to mechanical energy or
vice versa are now available for various energy conversion applications. One class of these
polymers, electroactive elastomers (also referred to as dielectric elastomers, electroelastomers, or
EPAMs) are increasingly noted. Electroactive elastomers can exhibit high energy density, stress,
and electromechanical coupling efficiency. The performance of these polymers is pronounced
when the polymers are prestrained in area. For example, increasing the area by a factor of 10 to
25 improves the performance of many electroactive elastomers. Actuators and transducers made
using these materials are significantly cheaper, lighter, and have a wider operating range as
compared to conventional techniques used to perform thermodynamic work on fluids in fluid
systems I see.
[0017]
JP 2001-286162 A
[0018]
Thus, improved techniques for achieving these high performance polymers in devices used to
perform thermodynamic work on fluids in fluid systems are desired.
[0019]
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The present invention describes devices that perform thermodynamic work on fluids, such as
pumps, compressors and fans.
Thermodynamic work can be used to provide a motive force to move the fluid.
The work done on the fluid may be transmitted to other devices such as pistons in the hydraulic
drive device. The device may include one or more electroactive polymer transducers with
electroactive polymers that flex in response to the application of an electric field. The
electroactive polymer can be in contact with the fluid, wherein deflection of the electroactive
polymer can be used to perform thermodynamic work on the fluid. The device may be designed
to operate efficiently at multiple operating conditions, such as operating conditions that produce
acoustic signals above or below human hearing. The device may be used in thermal control
systems such as refrigeration systems, cooling systems and heating systems.
[0020]
One aspect of the invention provides a device for performing thermodynamic work on a fluid.
This device can be broadly characterized as comprising: I) one or more transducers, each
transducer comprising at least two electrodes and an electroactive polymer electrically connected
to the at least two electrodes, a portion of the electroactive polymer being an electric field One or
more transducers configured to deflect from the first position to the second position in response
to the change, at least one surface contacting the fluid and operably coupled to said one or more
transducers; The deflection of the portion of the electroactive polymer causes the thermodynamic
work to be performed on the fluid, and the thermodynamic work is transmitted to the fluid via
the one surface. It is a surface. Deflection of a portion of the electroactive polymer can generate
one of rotational, linear, oscillatory, or a combination thereof on one surface. The thermodynamic
work may provide a driving force to move the fluid from the first position to the second position.
[0021]
The device may be one of a pump, a compressor, a hydraulic actuator and a fan. In particular, the
device can be one of an air compressor, a bellows pump, a fuel pump and a centrifugal pump.
The device is one of a pump or a compressor for a refrigeration system.
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[0022]
The device can be a fan used in a ventilation system, the fluid is air. The device may be used in a
thermal control system to control the temperature at one or more locations in the second device.
As an example, the second device is a computer, and one of the locations is near a
microprocessor for the computer. The fluid may be used to conduct thermal energy from a first
position to a second position in the second device. In certain embodiments, at least a portion of
the fluid is in a liquid phase.
[0023]
In certain embodiments, the device may further comprise a chamber for receiving the fluid,
wherein the bounding surface of the chamber comprises the one surface. The deflection of the
portion of the electroactive polymer causes a change in volume of the chamber. The change in
volume in the chamber may compress the fluid, expand the fluid, draw fluid into the chamber, or
drive fluid out of the chamber. The change in the volume in the chamber can cause a
thermodynamic phase change in at least a portion of the fluid, such as from liquid to gas or from
gas to liquid.
[0024]
In another embodiment, the chamber may be formed from one of a bladder or a bellows. The
deflection of the portion of the electroactive polymer may push the bladder or bellows to reduce
the volume of the bladder or bellows. The deflection of the portion of the electroactive polymer
may stretch the bladder or bellows to increase the volume of the bladder or bellows. In yet
another embodiment, the chamber is formed of a cylinder and a piston, and the one surface may
be part of a piston head.
[0025]
In another embodiment, the device further comprises a fan blade, and the one surface may be
part of the surface of the fan blade. The deflection of the portion of the electroactive polymer
may cause the fan blade to rotate. The deflection of the portion of the electroactive polymer 1)
allows the shape of the fan blade to change the aerodynamic performance of the fan blade, and
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2) allows the pitch of the fan blade to be changed, 3) This may cause a change in one of the
aeroelastic or aeroacoustic properties of the fan blade. The fan blades may be elements in a fan,
pump or compressor.
[0026]
The device includes one or more fluid conduits used to provide at least a portion of a flow path
that allows the fluid to move through the device, and a flow rate, flow, of the fluid through the
flow path. It may further comprise one or more valves controlling one of the directions, and
combinations thereof. The one or more valves may be check valves. The device may further
comprise a heat exchanger for applying or removing thermal energy to the fluid. In certain
embodiments, one or more portions of the electroactive polymer can act as the heat exchanger.
[0027]
In another embodiment, the deflection of the portion of the electroactive polymer induces a wave
motion in the one surface, and the wave motion may perform the thermodynamic work on the
fluid. The device may further comprise a fluid conduit, wherein the deflection of the portion of
the electroactive polymer may cause the fluid to move through the fluid conduit by generating a
peristaltic motion within the fluid conduit, or the electricity The deflection of the portion of active
polymer may cause the fluid in the fluid conduit to move through the conduit by generating a
peristaltic motion within the fluid conduit. A portion of the fluid conduit may be comprised of an
EPAM roll transducer.
[0028]
In another embodiment, the device is a forced return mechanism, wherein the forced return
mechanism provides at least a portion of a force by which the portion of the electroactive
polymer returns from the second position to the first position. It may further comprise a forced
return mechanism. The forced return mechanism can be a spring. The device may further
comprise a biasing mechanism that biases in the direction of deflection of the portion of the
electroactive polymer. The biasing mechanism may be one of a spring or an insertion. The device
further comprises an output shaft receiving an oil pressure generated from the pressure in the
fluid, the deflection of the portion of the electroactive polymer increasing the pressure in the
fluid, the oil pressure moving the output shaft I will provide a.
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[0029]
In still other embodiments, the device can be a stage in one of a multi-stage pump or a multistage compressor. The acoustic signal generated by the operation of the device may be above or
below the human hearing range. Furthermore, the operating frequency at which the portion of
the electroactive polymer deflects is above or below the human hearing range. For example, the
operating frequency may be less than 30 Hz.
[0030]
The device may further comprise a housing containing the one or more transducers and the one
surface. The flatness parameter, defined as the square of the height of the housing divided by the
footprint area of the housing, may be substantially less than one. In particular, the flatness
parameter may be less than about 0.1. Alternatively, the flatness parameter may be less than
about 0.05. Further, the flatness parameter may be less than about 0.01.
[0031]
In certain embodiments, the device further comprises a clamp plate having a plurality of
openings, and the electroactive polymer can be an electroactive polymer film designed to flex
into the plurality of openings. Furthermore, the device may further comprise a lower chamber
mounted to the clamp plate and designed to clamp the film between the clamp plate and the
lower chamber. A pump chamber for receiving the fluid may be formed by a portion of the
surface of the lower chamber and a portion of the surface of the film. The lower chamber may
further comprise one or more fluid conduits directing the fluid to the pump chamber and
directing the fluid away from the pump chamber.
[0032]
In certain embodiments, the deflection of the portion of the electroactive polymer can cause the
one surface to change from a first shape to a second shape. For example, the one surface may
expand to form one of a balloon-like, hemispherical, cylindrical or semi-cylindrical shape. The
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one surface may be operably coupled to the one or more transducers via a mechanical linkage.
Additionally, the one surface may be an outer surface of the portion of the electroactive polymer.
[0033]
The fluid may be one of compressible, incompressible, or a combination thereof. The fluid may be
one of homogeneous or heterogeneous. Furthermore, the fluid may behave as a Newton or nonNewtonian fluid. The fluid may be selected from the group consisting of mixtures, slurries,
suspensions, mixtures of two or more immiscible liquids, and combinations thereof. The fluid
may comprise one or more components in a state selected from the group consisting of liquids,
gases, plasmas, solids, phase changes, and combinations thereof.
[0034]
In another embodiment, the electroactive polymer may be selected from the group consisting of
silicone elastomers, acrylic elastomers, polyurethanes, copolymers comprising PVDF, and
combinations thereof. The device is designed or configured to be secured to the one or more
transducers with an insulating barrier designed or configured to protect the one surface from
components of the fluid in contact with the one surface. The above support structure can be
further provided. The electroactive polymer may improve mechanical response of the
electroactive polymer between the first position and the second position by being elastically prestrained at the first position. The electroactive polymer can have a modulus of less than about
100 MPa and can have an elastic area strain of at least about 10 percent between the first
position and the second position.
[0035]
The polymer comprises a multilayer structure, said multilayer structure comprising two or more
layers of electroactive polymer. The device may be fabricated on a semiconductor substrate.
[0036]
These and other features and advantages of the present invention are described in the following
description of the invention and the associated drawings.
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[0037]
FIG. 7 is a top view of the transducer portion prior to application of a voltage according to an
embodiment of the present invention.
FIG. 6A is a top view of a transducer section after application of a voltage according to an
embodiment of the invention. FIG. 1 shows an electroactive polymer (EPAM) device utilizing
flagellar motion to perform thermodynamic work on fluid. FIG. 1 shows an electroactive polymer
(EPAM) device utilizing flagellar motion to perform thermodynamic work on fluid. FIG. 1 shows
an electroactive polymer (EPAM) device utilizing flagellar motion to perform thermodynamic
work on fluid. FIG. 1 shows an electroactive polymer (EPAM) device utilizing flagellar motion to
perform thermodynamic work on fluid. FIG. 1 shows an electroactive polymer (EPAM) device
with a bellows that performs thermodynamic work on fluid. FIG. 1 shows an electroactive
polymer (EPAM) device with a bellows that performs thermodynamic work on fluid. FIG. 1
illustrates an electroactive polymer (EPAM) device that performs thermodynamic work on a fluid
with a piston driven by an EPAM transducer and an EPAM transducer that controls the volume of
the piston cylinder. FIG. 1 illustrates an electroactive polymer (EPAM) device that performs
thermodynamic work on a fluid with a fan driven by an EPAM transducer and an EPAM
transducer that controls the shape and attitude of the fan blade. FIG. 5 illustrates an electroactive
polymer (EPAM) spherical pump device that circulates a cooling fluid around a heat source. FIG.
1 illustrates an embodiment of an electroactive polymer (EPAM) peristaltic pump device. FIG. 1
illustrates an embodiment of an electroactive polymer (EPAM) wave motion pump device. FIG. 7
illustrates an embodiment of a bellows spring roll transducer. FIG. 7 illustrates an embodiment of
a bellows spring roll transducer. FIG. 1 shows a first embodiment of an EPAM tube pump device.
FIG. 1 shows a first embodiment of an EPAM tube pump device. FIG. 7 illustrates an embodiment
of an EPAM hydraulic cylinder device. FIG. 7 illustrates an embodiment of an EPAM hydraulic
cylinder device. FIG. 7 shows a second embodiment of an EPAM tube pump device. FIG. 6
illustrates an embodiment of an EPAM diaphragm array pump. FIG. 1 shows an embodiment of
an EPAM film pump. FIG. 1 shows an embodiment of an EPAM film pump. FIG. 7 illustrates an
embodiment of a multi-stage EPAM compressor or pump device. FIG. 7 illustrates an embodiment
of a multi-stage EPAM compressor or pump device.
FIG. 1 shows a rolled electroactive polymer device according to an embodiment of the present
invention. FIG. 1 shows a rolled electroactive polymer device according to an embodiment of the
present invention. FIG. 1 shows a rolled electroactive polymer device according to an
embodiment of the present invention. FIG. 1 shows a rolled electroactive polymer device
according to an embodiment of the present invention. FIG. 2B shows an end piece of the rolled
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electroactive polymer device of FIG. 2A according to an embodiment of the present invention.
FIG. 6 illustrates a bending transducer that provides variable stiffness based on structural
changes associated with polymer deflection according to an embodiment of the present
invention. FIG. 4B shows the transducer of FIG. 4A with a 90 degree bend angle. FIG. 7 shows a
bow device suitable for providing variable stiffness according to another embodiment of the
present invention. FIG. 4C shows the bow device of FIG. 4C after actuation. FIG. 7 shows a
monolithic transducer with multiple active areas on a single polymer according to an
embodiment of the present invention. FIG. 6 illustrates a monolithic transducer with multiple
active areas on a single polymer prior to rolling according to an embodiment of the present
invention. FIG. 5 shows a wound transducer producing a two-dimensional output according to an
embodiment of the present invention. FIG. 4L shows the wound transducer of FIG. 4L driven for
one set of radially aligned active areas. FIG. 7 is an electrical block diagram of an open loop
variable stiffness / braking system according to an embodiment of the present invention. FIG. 6 is
a block diagram of one or more active areas connected to power conditioning electronics. FIG. 1
is a circuit block diagram of a device employing a rolled electroactive polymer transducer
according to an embodiment of the present invention. FIG. 1 is a block diagram of a sensor
employing an electroactive polymer transducer according to an embodiment of the present
invention. FIG. 1 is a block diagram of a human body connected to an EPAM device that performs
thermodynamic work on fluid. FIG. 1 is a block diagram of a car and a car subsystem employing
an EPAM device that performs thermodynamic work on fluid. FIG. 1 is a block diagram of an
EPAM device that fluidizes thermodynamic work on an inkjet printer.
[0038]
The invention will be described in detail with reference to several preferred embodiments
illustrated in the attached drawings. In the following description, numerous specific details are
set forth in order to provide a thorough understanding of the present invention. However, it will
be apparent to one skilled in the art that the present invention may be practiced without some or
all of these specific details. Alternatively, known process steps and / or structures have not been
described in detail in order not to unnecessarily obscure the present invention.
[0039]
1. Electroactive polymer
[0040]
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Before describing the electroactive polymer (EPAM) flow control device of the present invention
that performs thermodynamic work on fluid in Section 1, the basic principles of construction and
operation of the electroactive polymer refer to FIGS. 1A and 1B. Will be explained first. In section
2, embodiments of devices and systems with EPAM transducers such as pumps, compressors,
fans and hydraulic cylinders and their operation are described with reference to FIGS. 2A-2K and
3A-3J. . In section 3, embodiments of the EPAM transducer of the present invention are
described with reference to FIGS. 4A-4N. In section 4 detection applications are described. In
section 5, the conditioning electronics of the present invention are described for FIGS. 5A and 5B.
Several applications are described in Section 6, such as biological applications, automotive
applications and printing applications.
[0041]
The conversion between electrical and mechanical energy in the device of the invention is based
on energy conversion of one or more active regions of the electroactive polymer. Electroactive
polymers can be converted between mechanical energy and electrical energy. In some cases,
electroactive polymers can change electrical properties (eg, capacitance and resistance) due to
changing mechanical strain.
[0042]
To help illustrate the performance of the electroactive polymer in converting between electrical
energy and mechanical energy, FIG. 1A is a top perspective view of a transducer portion 10
according to an embodiment of the present invention. Transducer portion 10 includes a portion
of electroactive polymer 12 that converts between electrical energy and mechanical energy. In
one embodiment, an electroactive polymer refers to a polymer ("dielectric elastomer") that
functions as an insulating dielectric between two electrodes and can flex in response to the
application of a voltage difference between the two electrodes. Upper and lower electrodes 14
and 16 are attached to electroactive polymer 12 on its upper and lower surfaces, respectively, to
provide a voltage differential across polymer 12 or to receive electrical energy from polymer 12.
The polymer 12 can flex with changes in the electric field provided by the upper and lower
electrodes 14 and 16. The deflection of the transducer portion 10 in response to changes in the
electric field provided by the electrodes 14 and 16 is referred to as "actuation." Driving typically
involves the conversion of electrical energy to mechanical energy. As the polymer 12 changes in
size, deflection can be used to create mechanical work.
05-05-2019
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[0043]
While not wishing to be bound to a particular theory, in certain embodiments, polymer 12 may
be considered to behave in an eclectic manner. The term electrostrictive is used herein in a
general sense to describe the stress and strain response of a material to the square of the electric
field. This term is often used exclusively to refer to the strain response of a material in an electric
field that originates from an intramolecular force induced by the electric field, but here the term
more generally refers to other mechanisms that cause a response to the square of the electric
field. Electrical conduction is distinguished from piezoelectric behavior in that the response is not
proportional to the electric field but to the square of the electric field. The deflection of a
polymer with a compliant electrode can result from the electrostatic force (sometimes referred to
as "Maxwell stress") generated between the free charges on the electrodes and is proportional to
the square of the electric field. The actual strain response in this case can be quite complex
depending on the internal and external forces of the polymer, but this electrostatic pressure and
stress is proportional to the square of the electric field. FIG. 1B is a top perspective view of the
transducer portion 10 including a deflection. In general, deflection refers to any displacement,
elongation, contraction, twisting, linear or areal strain, or any other deformation of a portion of
the polymer 12. Changes in the electric field corresponding to the potential differences applied to
or by electrodes 14 and 16 for actuation create mechanical pressure in polymer 12. In this case,
the charges of different polarity created by the electrodes 14 and 16 are attracted to each other
to provide a compressive force between the electrodes 14 and 16 and to provide a stretching
force in the planar directions 18 and 20 on the polymer 12, The polymer 12 compresses
between the electrodes 14 and 16 and acts to elongate in the planar directions 18 and 20.
[0044]
The electrodes 14 and 16 are extensible and change shape with the polymer 12. The
configuration of polymer 12 and electrodes 14 and 16 serve to increase the response of polymer
12 to strain. More specifically, as the transducer portion 10 flexes, the compression of the
polymer 12 brings the opposite charges of the electrodes 14 and 16 closer, and the extension of
the polymer 12 separates the same charge at each electrode. In one embodiment, one of the
electrodes 14 and 16 is connected to ground. For actuation, the transducer portion 10 generally
continues to flex until mechanical stress balances the electrostatic forces that drive the
deflection. Mechanical stresses include the elastic recovery of the polymer 12 material, the
compliance of the electrodes 14 and 16, and any external resistance provided by the device and /
or load coupled to the transducer portion 10. The deflection of the transducer portion 10 as a
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result of the applied voltage also depends on many other factors such as the dielectric constant
of the polymer 12 and the size of the polymer 12.
[0045]
The electroactive polymer according to the present invention can flex in any direction. After
applying a voltage between the electrodes 14 and 16, the electroactive polymer 12 increases in
size in both planar directions 18 and 20. In some cases, electroactive polymer 12 is
incompressible, eg, having a substantially constant volume under stress. In this case, the polymer
12 has a reduced thickness as a result of the expansion in the planar directions 18 and 20. The
present invention is not limited to incompressible polymers, and deflection of polymer 12 may
not follow such a simple relationship.
[0046]
By applying a relatively large voltage difference between the electrodes 14 and 16 of the
transducer 10 shown in FIG. 1A, the transducer portion 10 is changed to a thinner, larger area
shape as shown in FIG. 1B. Thus, the transducer unit 10 converts electrical energy into
mechanical energy. Transducer portion 10 may also be used to convert mechanical energy into
electrical energy.
[0047]
To drive, the transducer portion 10 generally continues to flex until the mechanical force is
balanced with the electrostatic force that drives the deflection. Mechanical forces include elastic
recovery of the polymer 12 material, compliance of the electrodes 14 and 16, and any external
resistance provided by the device and / or load coupled to the transducer portion 10. The
deflection of the transducer portion 10 as a result of the applied voltage also depends on many
other factors such as the dielectric constant of the polymer 12 and the size of the polymer 12.
[0048]
In one embodiment, electroactive polymer 12 is pre-strained. The prestrain of a polymer can be
05-05-2019
16
described as the change in dimension in one or more directions before the prestrain relative to
the dimension in that direction after the prestrain. Pre-strain can include elastic deformation of
the polymer 12 and can be formed, for example, by stretching the polymer under tension and
securing one or more edges while stretching. Alternatively, as detailed below, a spring-like
mechanism may be coupled to the different portions of the electroactive polymer to provide a
force to strain the portions of the polymer. For many polymers, prestrain improves the
conversion between electrical and mechanical energy. The improved mechanical response allows
for greater mechanical work for the electroactive polymer, such as greater deflection and drive
pressure. In one embodiment, pre-strain improves the dielectric strength of the polymer. In
another embodiment, the prestrain is elastic. After actuation, the elastically prestrained polymer
is in principle not fixed and returns to its original state.
[0049]
In one embodiment, prestrain is applied uniformly across portions of polymer 12 to make an
isotropic prestrained polymer. As an example, the acrylic elastomeric polymer can be stretched
by 200 to 400 percent in both directions. In another embodiment, prestrain is applied unevenly,
in different directions on portions of the polymer 12, to make an anisotropic prestrain polymer.
In this case, when driven, the polymer 12 may deflect more in one direction than in the other
direction. While not wishing to be bound by theory, pre-straining the polymer in one direction
can increase the stiffness of the polymer in the pre-strain direction. Correspondingly, the
polymer is relatively stiff in the high prestrain direction and more compliant in the low prestrain
direction, and when driven, more deflection occurs in the low prestrain direction. In one
embodiment, the deflection of the direction 18 of the transducer portion 10 may be enhanced by
utilizing a large pre-strain in the vertical direction 20. For example, the acrylic elastomeric
polymer used as the transducer portion 10 may be stretched by 10% in the direction 18 and
500% in the direction 20. The amount of pre-strain of the polymer may depend on the polymer
material and the desired performance of the polymer in certain applications. Pre-strains suitable
for use with the present invention are further described in commonly owned co-pending US
patent application Ser. No. 09 / 619,848, which is incorporated herein by reference for all
purposes. Ru.
[0050]
Generally, after the polymer is pre-strained, it can be fixed to one or more objects or mechanisms.
For rigid objects, the object is preferably suitably rigid to maintain the desired level of pre-strain
in the polymer. A spring or other suitable mechanism that provides a force to strain the polymer
05-05-2019
17
can be added to any previously established prestrain in the polymer prior to being attached to
the spring or mechanism or in the polymer It can be the cause for all of the predistortion. The
polymer may be affixed to one or more objects or mechanisms by any conventional method
known in the art, such as chemical bonding, adhesive layers or materials, mechanical fastening,
and the like.
[0051]
The transducers and pre-strained polymers of the present invention are not limited to any
particular wound geometry or type of deflection. For example, the polymer and the electrode
may be mounted across a frame of any geometrical configuration including cylindrical and
multilayer winding cylinders, wound polymers attached between rigid structures, curved or
complex geometric configurations It may be formed into any geometric configuration and shape,
including spiral wound polymers and the like. Similar structures may be used with flat sheet
polymers. The deflection of the transducer according to the invention may be linear expansion or
compression in one or more directions, bending, axial deflection when the polymer is wound,
deflection out of a hole provided on the outer cylinder around the polymer, etc. including.
Transducer deflection is affected by how much the polymer is constrained by the frame or rigid
structure attached to the polymer.
[0052]
Materials suitable for use as the electroactive polymer of the present invention include any
substantially insulating polymer or rubber (or their derivatives that deform in response to
electrostatic forces, or the deformation leads to a change in electric field. Combination) is
included. One suitable material is NuSil CF 19-2186, provided by NuSil Technology of
Carpenteria, California. Other exemplary materials suitable for use as pre-strained polymers
include silicone elastomers, acrylic elastomers such as acrylic elastomers manufactured by 3M
Corporation of St. Paul, Minnesota, thermoplastic elastomers, PVDF And copolymers containing
pressure sensitive adhesive materials, fluorinated elastomers, polymers containing silicone and
acrylic components, and the like. Polymers containing silicone and acrylic components include
copolymers containing silicone and acrylic components, polymer blends containing silicone
elastomers and acrylic elastomers, and the like. Several combinations of these materials may also
be used as the electroactive polymer in the transducer of the present invention.
[0053]
05-05-2019
18
Materials used as electroactive polymers can be selected based on one or more material
properties such as high electrical breakdown strength, low modulus (for large or small
deformation), high dielectric constant, and the like. In one embodiment, the polymer is selected
to have a modulus of at most about 100 MPa. In another embodiment, the polymer is selected
such that it has a maximum driving pressure of between about 0.05 MPa and about 10 MPa,
preferably between about 0.3 MPa and about 3 MPa. In another embodiment, the polymer is
selected such that it has a dielectric constant between about 2 and about 20, preferably between
about 2.5 and about 12. The present invention is not limited to these ranges. Ideally, if the
material has both high dielectric constant and high dielectric strength, materials with dielectric
constants higher than the ranges given above are desirable.
[0054]
The electroactive polymer layer of the transducer of the present invention can have a wide range
of thicknesses. In one embodiment, the thickness of the polymer is in the range between about 1
micrometer and 2 millimeters. The polymer thickness can be reduced by stretching the film in
one or both planar directions. In many cases, the electroactive polymers of the present invention
are manufactured and realized as thin films. A suitable thickness for these films can be less than
50 micrometers.
[0055]
Because the electroactive polymers of the present invention can deflect at high strains, electrodes
attached to the polymer also need to deflect without compromising mechanical or electrical
performance. Generally, electrodes suitable for use with the present invention can be any shape
and material from which they can apply or receive an appropriate voltage to the electroactive
polymer. The voltage can either be constant or variable with time. In one embodiment, the
electrode adheres to the surface of the polymer. The electrode adhering to the polymer is
preferably compliant and follows the shape change of the polymer. Correspondingly, the
invention may include electrodes with compliance that conforms to the shape of the electroactive
polymer to which they are attached. The electrodes may be applied to only a portion of the
electroactive polymer, and the geometry may define the active area. Some examples of electrodes
that cover only a portion of the electroactive polymer are detailed below.
05-05-2019
19
[0056]
Various types of electrodes suitable for use with the present invention have been described in coowned co-pending US patent application Ser. No. 09 / 619,848, which has already been
incorporated by reference above. Electrodes suitable for use with the invention described therein
include structured electrodes including metal traces and charge distribution layers, patterned
electrodes including various out-of-plane dimensions, conductive greases such as carbon grease
or silver grease, Included are colloidal suspensions, high aspect ratio conducting materials such
as carbon fibrils and carbon nanotubes, and mixtures of ion conducting materials.
[0057]
There are various materials used for the electrode of the present invention. Suitable materials for
use as electrodes include graphite, carbon black, colloidal suspensions, thin metals including
silver and gold, silver-filled or carbon-filled gels or polymers, ionic or electronic And polymers
having conductivity. In a specific embodiment, an electrode suitable for use with the present
invention is Stockwell Rubber Co. Inc., Philadelphia, PA. Contains 80 percent carbon grease and
20 percent carbon black in a silicone rubber binder such as Stockwell RTV 60-CON
manufactured by: Carbon grease is available from Nye Lubricant Inc., Fairhaven, Massachusetts.
The type is provided by NyoGel 756G. The conductive grease may also be mixed with an
elastomer such as RTV 118 manufactured by General Electric of Waterford, NY to provide a gellike conductive grease.
[0058]
It will be appreciated that it is possible that some electrode materials work well with certain
polymers and not with others. As an example, carbon fibrils work well with acrylic elastomeric
polymers but not with silicone polymers. For most transducers, desirable characteristics for a
compliant electrode may include one or more of the following. Low modulus, low mechanical
damping, low surface resistance, uniform resistance, chemical and environmental stability,
chemical compatibility with electroactive polymers, good adhesion to electroactive polymers, and
smooth surfaces The ability to form In some cases, the transducers of the present invention may
utilize two different types of electrodes, such as different electrode types for each active area, or
different electrode types on the opposite side of the polymer.
05-05-2019
20
[0059]
2. EPAM device that performs thermodynamic work on fluid
[0060]
The present invention describes a device that applies thermodynamic work on fluids such as
pumps, compressors, and fans (see FIGS. 2A-3J). Thermodynamic work may be used to provide a
driving force to move the fluid. The work applied to the fluid may be transferred to other devices
such as pistons (Figures 3C and 3D) in a hydraulic actuation device. The device may include one
or more electroactive polymer transducers with electroactive polymers (eg, FIGS. 1A-1B and 4A4M) that flex in response to the application of an electric field. The electroactive polymer can be
in contact with the fluid where deflection of the electroactive polymer can be used to perform
thermodynamic work on the fluid. The device may be designed to operate efficiently in multiple
operating conditions, such as operating conditions that produce acoustic signals above or below
the human hearing range. The device may be used in thermal control systems such as
refrigeration systems, cooling systems and heating systems (see, eg, FIGS. 2A-2D and 2I).
[0061]
In the present invention, an EPAM device is described that provides thermodynamic work on a
fluid. The laws of thermodynamics deal with interactions between the system and its
surroundings. In one definition, thermodynamic work is if the system goes through the same set
of states as the original process, but the only effect in the outside world is weight gain, if any
other processes are found It can be said that it is done by the system. For example, a storage
battery considered as a system can be discharged to light a light bulb. If the light bulb is replaced
with an electric motor having a very large conductor and a pulley on which a weight hanging
thread is wound, the battery will go through the same sequence of conditions but at the net
outside, except for the rise in weight. It has no effect. Therefore, it can be said that the storage
battery performs thermodynamic work in the original process. When a system does work to its
external world, the external world receives the same amount of work from the system. Details of
thermodynamic work by systems and specific thermodynamic work in fluid systems are
described in “The Dynamics and Thermodynamics of compressible fluid flow”, 1953, by
Shapiro, John Wiley and Sons, ISBN 047106691-5, The whole is incorporated herein by
reference for all purposes.
05-05-2019
21
[0062]
In the present invention, embodiments of EPAM devices with EPAM transducers that perform
thermodynamic work on fluids are described. The fluids of the present invention may comprise
materials in the form of liquids, gases, plasmas, phase changes, solids or combinations thereof.
The fluid may behave as a non-Newtonian fluid or a Newtonian fluid. Furthermore, the fluid may
be homogeneous or heterogeneous. The fluid may also be incompressible or compressible.
Examples of fluids of the present invention include, but are not limited to, gases, plasma, liquids,
mixtures of two or more immiscible liquids, supercritical fluids, slurries, suspensions, and
combinations thereof.
[0063]
Figures 2A-2D illustrate electroactive polymer (EPAM) devices that use flagellar motion to apply
thermodynamic work to the fluid. In FIG. 2A, a linear flagellar pump comprising four EPAM
transducers attached to a support structure 303 is shown. The EPAM transducer 302 may be
shaped as a roll as shown in FIG. 4M or as a flat sheet as shown in FIGS. 4F and 4G. In general,
the geometry of the EPAM transducer can be adapted to any general shape required for the
application. The EPAM transducer 302 can be controlled to perform an undulating motion from
the support structure to the end of the transducer so that the fluid moves approximately parallel
to that indicated by the flow direction arrow 301. Similar to the way a person uses a manual fan,
the flexing elements (such as a single form structure with a non-stretching element bonded to an
electroactive polymer with electrodes) are rapidly shaken to create an air flow. Wavy motion can
be amplified by operating at one of the fan's natural frequencies.
[0064]
The fluid may stagnate prior to actuation of the EPAM transducer, or the fluid may have an initial
velocity profile. The EPAM transducers 303 can be controlled independently. For example, the
wave motion on each transducer may generally be the same or different. The transducers can
also be driven in a time-varying sequence. For example, wave motion is initiated on the first pair
of transducers, the other two remain inactive, and then on the other pair of transducers after
motion on the first pair of transducers is complete. Wave movement may begin. The transducers
may operate in synchronization or not. In one embodiment, if the support structure 303 is not
fixed, the thermodynamic work done by the transducer on the fluid can be used to advance the
05-05-2019
22
support structure 303, and the transducer moves forward in the fluid.
[0065]
In Figures 2B and 2C, an embodiment of a radial flagellar pump is shown. Again, four EPAM
transducers are attached to the support structure. The EPAM transducer may be controlled to
move the fluid radially outward from the center of the support structure. For example, if the
support structure is located above the heat source, the radial motion generated by the pump 305
may be used to move the heated fluid away from the heat source.
[0066]
In an embodiment, the support structure 303 can be mounted on a pivot that allows the support
structure 303 to rotate. In this embodiment, motion of the transducer may be generated to
impart angular momentum to the support structure 303. In this case, all of the support structure
and the transducer may begin to rotate like a fan moving fluid in a direction that is generally
perpendicular to the radial motion in the direction of fluid 301. When the transducers behave
like fan blades, their shape, such as their pitch, can be controlled to increase or decrease their
aerodynamic efficiency. Further details of the dynamic EPAM fan blade are described for FIG. 2H.
[0067]
In FIG. 2C, the EPAM transducer 302 is configured to direct the fluid radially inward to a position
approximately centered on the four transducers. For example, the location between the four
transducers can be the vent of the system, such as the vent of a computer system's case such as a
personal computer. In other embodiments, four transducers may be used for thermal control, and
the location between the four transducers may be a cooling spot to which warm fluid is directed.
[0068]
To a large extent, the EPAM device that provides the thermodynamic work of the present
invention can be used as an element in a thermal control system. For example, multiple EPAM
05-05-2019
23
devices may be wired to a central controller, such as a microcontroller or microprocessor. The
central controller may also be connected to multiple sensors such as flow rate sensors and
temperature sensors. In one embodiment, the EPAM device can act as a sensor or sensing system
(see Section 4). The central controller may monitor temperature sensors and flow rate sensors
and maintain a predetermined temperature distribution in the system being monitored by
controlling the EPAM transducers. For example, the system can be a manufactured article that
needs to be cooled or heated with a very uniform heat distribution to prevent thermal stress from
accumulating in the article during the cooling or heating process.
[0069]
In FIG. 2D, a variable linear flagellar pump is shown. In this embodiment, the size of the
transducer is variable. The two middle transducers are longer than the two outer transducers.
Thus, the intermediate flow rate can be greater than the outside. However, in certain
embodiments, this effect may be achieved by moving transducers of the same shape, simply or
faster or slower with respect to each other, or with different motion patterns. The transducer 302
is located next to the cooling fin 307. Cooling fins may be used to direct the heat moved through
the cooling fins by the motion of the transducer 302 away from the fluid. Cooling fins and
transducers can be part of a larger thermal control system.
[0070]
In some embodiments, the transducer 302 can be used to direct heat away from the fluid or to
add heat to the fluid as part of a thermal control system. For example, the transducer may be
designed to direct heat to the support structure 303. The support structure 303 may include a
heat sink and a connection to a heat conduit that removes heat from the heat sink in the support
structure. EPAM polymers may be used as thermal conductors or thermal insulators. Thus, the
material properties of the EPAM polymer in the transducer can be designed to increase or
decrease the thermal conductivity of the material required by the particular system.
[0071]
In one embodiment, a transducer with 1 to 20 mm of bending elements (ie, flagella) may be used
for microchip cooling. EPAM transducers can be capable of large bending angles. For example,
the device may generate a bend greater than 270 degrees in the range of 5 to 10 mm. Larger
05-05-2019
24
bend angles may allow greater fluid flow for microchip cooling.
[0072]
Microchip cooling with one or more flex polymer fans / pumps offers many potential advantages.
As shown in FIGS. 2A-2D, flex fans can be easily configured in many different ways, so that the
fans can be optimized for the specific cooling requirements of the microchip. The polymer
flexures can be efficient at low speeds (different from electric motors), capable of operating
below audio frequency, and can reduce or eliminate fan noise. Low noise is advantageous for
environments such as home entertainment systems. Flexure elements also eliminate bearing
noise and possible failure found in electromagnetic based microchip fans.
[0073]
2E-2F illustrate electroactive polymer (EPAM) devices with bellows that perform thermodynamic
work on fluid. In FIG. 2E, one embodiment of a bellows pump 310 is shown. An EPAM transducer
302 is connected between the support 313 and a support structure 303 with a flow conduit. The
support is attached to the support structure 303 by a linkage that allows the support 313 to
move about a linkage point with the support structure. There is a bladder 312 between the
support and the support structure. Two flow conduits 314 are connected to the chamber
bounded by the bladder 312.
[0074]
When a voltage is applied to the EPAM transducer 302, the transducer stretches, pushing up the
support 313 and moving against a forced return mechanism 311 such as a spring. The upward
movement increases the volume of the bladder, thereby drawing fluid into the bladder in the
direction indicated by the arrow. Fluid is drawn into the bladder via the suction created from the
increase in volume of the bladder. A check valve may be included in flow conduit 314 to ensure
that fluid flows in the direction indicated by the arrow. As the voltage is reduced or removed
from the transducer, the transducer 302 decreases in length and pulls the support downward. As
the support is pulled downward, the bladder 312 is pushed and fluid is expelled from the bladder
and out the front of the device 310. The flow rate out of the bladder 312 may be controlled by
the rate at which the voltage to the transducer 302 is reduced and by the force applied from the
return mechanism 311 to the support.
05-05-2019
25
[0075]
In FIG. 2F, a second embodiment of a bellows pump 315 is shown. The bellows pump includes a
bladder 312 designed to fold in an accordion-like manner when compressed. The sack portion
312 is mounted between the two support plates 303. Fluid conduits 314 pass through each of
the support plates 303. Fluid conduit 314 includes two check valves 316 that allow fluid to flow
in the direction indicated by the arrow. The support plate 303 is connected via a plurality of
EPAM transducers 302. The bladder 312 is surrounded by a forced return mechanism 311, such
as a coil spring.
[0076]
When energy is provided to the EPAM transducer 302, the EPAM transducer 302 extends in
length, and the bladder 312 increases in volume, draws fluid into the bladder and stretches the
coil spring 311. When energy to the EPAM transducer 302 is removed or reduced, the EPAM
transducer contracts and the support plate is attracted by the coil spring, reducing the volume of
the bladder 312 and fluid from the bladder 312 through the flow conduit Drive out There is no
need for a forced return mechanism (eg, a spring) and the EPAM device 315 can function without
the forced return mechanism. For example, when stretched, the mechanical force generated
within the EPAM polymer in transducer 302 may provide a return force as the voltage on the
EPAM polymer is removed or reduced. The transducer 302 can also be a tubular transducer that
completely surrounds the bellows. Tubular transducers are described in more detail below.
Besides bellows pumps, the invention can be used in many types of pump designs. These pump
designs include, but are not limited to, centrifugal pumps, diaphragm pumps, rotary pumps, gear
pumps, and air lift pumps.
[0077]
FIG. 2G shows an electroactive polymer (EPAM) device 320 that performs thermodynamic work
on fluid with a piston driven by the EPAM transducer and an EPAM transducer that controls the
volume of the piston cylinder. The piston drive pump 320 includes two fluid conduits with a
check valve 316 that restricts fluid movement in the direction of the arrow. The piston 317 is
designed to move 322 up and down within the cylinder 318. As the piston moves up, the volume
of the pump chamber formed by the cylinder and the piston increases and fluid is drawn into the
05-05-2019
26
pump chamber. As the piston moves downward, the volume of the pump chamber decreases and
fluid is pushed out of the chamber.
[0078]
In certain embodiments of the present invention, the top surface of the piston 317 may include
an EPAM transducer 323. For example, when the piston is cylindrical, EPAM transducer 323 can
be a cylindrical diaphragm. The EPAM transducer 323 can flex to change the volume of the
pump chamber. In conventional devices that use a piston, the volume of the pump chamber is
maximized at the top of its stroke and is minimized at the bottom of its stroke. The maximum and
minimum volumes, as well as the volumes between the maximum and minimum, are determined
at each position as the piston travels its path in the cylinder. In the present invention, the EPAM
transducer 323 can be flexed to change the volume of the pump chamber at each position as the
piston moves on its path in the cylinder.
[0079]
By bending the EPAM transducer 323 to change the volume of the pump chamber, the operating
conditions of the pump device, such as the amount of fluid pumped by the device, can be
changed. This effect may be achieved by controlling the speed at which the piston operates.
However, if it is advantageous to move the piston at a specific speed, as in consideration of
efficiency goals or noise, the fluid pumping rate will cause the EPAM transducer 323 to flex
without changing the rate at which the piston moves It can be changed by changing the volume
of the pump chamber.
[0080]
The piston 317 is driven by two EPAM transducers 302. The EPAM transducer 302 may increase
or decrease in length as indicated by the directional arrow 322 when a voltage is applied to the
transducer. Conditioning electronics and power supplies (see FIGS. 5A, 5B and 6), not shown,
may be used to power the transducer 302. The force in the direction of the motion 322 on the
support structure 303 generated by the transducer 302 may be transmitted by the mechanical
linkage 319 to generate the motion 322 of the piston 317 in the cylinder. There are various
mechanical linkages known in the prior art, and the invention is not limited to the example
shown in FIG. 2G.
05-05-2019
27
[0081]
Using an EPAM transducer to drive the piston 322 has many advantages over the use of a
conventional motor such as an electric motor. One advantage is that the EPAM transducer 302
generally weighs less than an electric motor. Another advantage is that EPAM transducers can
operate efficiently in more operating conditions than electric motors. The flexibility of the
operating conditions may be advantageous for problems such as minimizing noise from the
device 320 or controlling the device output. For example, an EPAM diaphragm transducer may
be used to efficiently expel fluid at operating frequencies less than 30 Hz. Details of EPAM
transducers used as motors, and further advantages of these devices, can be found in co-pending
US patent application Ser. No. 10/090, filed Feb. 28, 2002 by Heim et al. Entitled "Electroactive
Polymer Rotary Motors". , 430, which was previously incorporated herein.
[0082]
In another embodiment, piston driven pump 320 may be used as a compressor. To use device
320 as a compressor, appropriate valve design is used to prevent fluid from exiting the pump
chamber as the piston is compressing fluid in the pump chamber. The details of the EPAM valve
design that may be used with the piston driven pump 320 of the present invention and other
embodiments are co-pending with Heim et al., Filed March 5, 2003, entitled "Electroactive
Polymer Devices for Controlling Fluid Flow". No. 10 /, which is incorporated herein by reference
in its entirety.
[0083]
FIG. 2H shows an electroactive polymer (EPAM) device that performs thermodynamic work fluid
with a fan 325 driven by an EPAM transducer 328, and an EPAM transducer that controls the
shape and attitude of the fan blade. The fan 325 includes an annular plate 329 and two EPAM
roll type transducers 328 mounted to a base 327. Other types of EPAM transducers may also be
used with fan 325 and are not limited to the use of roll type transducers 328 (see Section 3 for a
further description of EPAM transducers). The annular plate is mounted to the support by a
linkage which allows the plate 329 to rotate. The support is mounted on a base 327. The three
fan blades are mounted to an annular plate 329.
05-05-2019
28
[0084]
When a voltage is applied to the roll transducer, the transducer 328 stretches and when the
voltage is removed, the transducer contracts. By applying a voltage to one of the transducers and
removing or reducing the voltage to the opposite one, the annular plate can be rotated clockwise
or counterclockwise. The speed of the fan (eg, the rate of rotation of the annular plate) may be
controlled by applying a time-varying voltage to the transducer 328.
[0085]
In one embodiment, the efficiency of fan 325 may be controlled by changing the shape of fan
blade 326. For example, each fan blade 391 may comprise a frame 329 having an EPAM
transducer 391 with one or more active areas. The shape of the fan blades may be changed by
flexing one or more active areas on the EPAM transducer 391. EPAM transducers with multiple
active areas are described for FIGS. 4J-4M. The shape of the fan blade may be changed to
increase or decrease its aerodynamic performance. Furthermore, the shape of the fan blade can
be changed to reduce the noise and vibration emitted from the blade at a specific operating
speed of the fan (aeroacoustic characteristics), the shape of the fan can be structural vibration
interaction within the fan blade Can be changed to limit or change (aeroelastic properties).
[0086]
Fan blade 326 may include a second EPAM transducer 390 designed to change the pitch of the
fan blade by rotating the blade. The aerodynamic performance of blade 326 may be a function of
its pitch. In one embodiment, instead of the two transducers 391 and 392, a single integrated
EPAM transducer may be used to change the shape of the blade and change its pitch.
[0087]
FIG. 2I shows an electroactive polymer (EPAM) spherical pump device 330 that circulates fluid
across heat source 331 to remove thermal energy from heat source 331. The spherical pump
device includes a spherically shaped EPAM transducer 333 that forms the boundary surface of
the pump chamber 334. The present invention is not limited to spherical shaped EPAM
05-05-2019
29
transducers 333 but transducers that deform to various general three dimensional shapes may
be used.
[0088]
The spherical cooling pump 330 can be part of a thermal control system that controls the
temperature of the heat source 331. In one embodiment, the heat source may be located in a
computing device. For example, the heat source can be a microprocessor. As part of the thermal
control system, the spherical cooling pump 330 is connected to a closed fluid conduit 335
carrying the fluid 336. In operation, a voltage is applied to the spherical EPAM transducer 333
which causes the EPAM polymer in the transducer to flex outwardly, causing the volume of the
pump chamber 334 to increase. The change in volume draws fluid 336 into the chamber. As the
voltage to the transducer 333 is removed or reduced, the EPAM polymer flexes inward to move
the fluid 336 from the pump chamber 334 to the fluid conduit 335.
[0089]
In the thermal control system of heat source 331, fluid 336 is designed to flow through the heat
source, where heat energy is transferred from heat source 331 to fluid 336 to cool heat source
331. Heated fluid flows from heat source 331 to heat exchange area 332 where thermal energy
is transferred from fluid 336. The cooled fluid is then circulated by the spherical cooling pump
330 and through the heat source 331 to pick up thermal energy from the heat source.
[0090]
In one embodiment, fluid conduit 335 may include an expansion valve that causes a phase
change, such as liquid phase to gas phase, which is common in refrigeration systems. Phase
change may be used to remove energy from fluid 336. In other embodiments, the fluid 336 may
change phase state, such as from liquid to gas, when the volume of the pump chamber is
expanded. Phase change can lead to fluid cooling. Additionally, a fluid such as a gas can be
expanded in the pump chamber to lower its temperature before being pumped through the heat
source.
[0091]
05-05-2019
30
In certain embodiments, a spherical transducer can serve as a heat exchange area. The EPAM
polymer may be designed as a multilayer structure with a conductive layer used to conduct heat
energy away from fluid 336 within pump chamber 334. In other embodiments, the EPAM
polymer may include an insulating layer to prevent the fluid from being heated by the
environment surrounding the pump chamber 334, as if the fluid 336 had been cooled prior to
entering the chamber 334. .
[0092]
FIG. 2J shows an embodiment of an electroactive polymer (EPAM) peristaltic pump device.
Peristaltic pump device 340 includes a fluid conduit 335 having an inlet 342 and an outlet 343
and a plurality of EPAM diaphragms located on the inner surface of fluid conduit 335. The
diaphragm array may be individually controlled to generate an undulating motion, ie, a peristaltic
motion that causes fluid to travel from the inlet 342 to the outlet 343. For example, the
diaphragm is flexed as a function of time starting at the inlet 342 and traveling to the outlet. This
wave motion carries the fluid in a pattern towards the outlet as the diaphragm is flexed in its
wave pattern.
[0093]
FIG. 2K shows a second embodiment of an electroactive polymer (EPAM) peristaltic pump device
345. FIG. Peristaltic pump device 345 comprises a fluid conduit 335 which is a hollow EPAM roll
transducer 328 (see FIGS. 4A-4E and 4K-4M). The roll transducer may be driven to generate a
wave (eg, a pile of transducers) that travels along the transducer in direction 344 as a function of
time. As the wave travels along the transducer 328, the wave can push fluid forward of it. Thus,
fluid may be moved from the inlet 342 to the outlet 343. After the wave has traveled to the
outlet, the wave can be generated again at the inlet 342 in a repeating pattern to provide a
continuous pumping action.
[0094]
In other embodiments, a change in diameter, such as a reduction in diameter, may be realized as
a wave traveling along the conduit. To generate waves, narrow diameters may be realized at
05-05-2019
31
different locations as a function of time along the conduit. As the position at which the conduit is
narrowed moves along the conduit, fluid can be pushed forward of the position at which the
conduit is narrowed, thereby creating a peristaltic pumping motion.
[0095]
One advantage of the pump described for FIGS. 2I, 2J and 2K is that the pump operation can be
performed without a separate motor. For example, in FIGS. 2I, 2J and 2K, movement of the EPAM
polymer used for pumping in the transducer is generated by supplying a voltage to the EPAM
polymer from a power source such as a battery. In a conventional piston drive pump, the
movement of the piston is driven by a separate motor, such as an electric motor. The motor adds
weight to the system. Furthermore, motors are typically only efficient at a limited number of
operating conditions, such as rotational speed. Thus, additional gearing may be required to use
energy from the motor at a different rate than its optimal operating conditions. Thus, the EPAM
pump device of the present invention has the ability to be much lighter than conventional pump
systems by eliminating separate motors and their associated mechanical linkages.
[0096]
2L and 2M show cross sections of one embodiment of a bellows spring roll transducer 600. FIG.
For bellows spring roll actuator manufacture, EPAM materials such as acrylic film (s) may be prestrained and wound on a bellows spring 601. The bellows spring 601 can form a closed chamber.
The spring 601 holds the EPAM film in tension. End structure 351 may be used to seal the top of
the bellows spring. In certain embodiments, end structures are not required. The fluid conduit
extends through the end structure to allow fluid 336 to enter the chamber formed by the bellows
spring 601.
[0097]
When the EPAM film in transducer 353 is driven, the spring can extend longitudinally as the
EPAM film becomes longer and the inside diameter of spring 601 can increase. If the fluid is
already under pressure, increasing the diameter of the spring allows for greater flow rate in the
device. Thus, the flow rate can be controlled by changing the diameter of the bellows spring 601
by applying or removing voltage from the EPAM in the transducer. For pump operation, check
valve 316 may be added to transducer 600 as shown. When the EPAM film is not driven, the roll
05-05-2019
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shortens in length and the diameter between the springs decreases. This motion may be used to
force fluid out of the chamber within the bellows spring 601.
[0098]
Figures 3A and 3B illustrate a first embodiment of an EPAM tube type pump device 350. The
tube pump device may comprise one or more electroactive polymer transducers. The pump may
be made using one or more rolls of electroactive polymer (EPAM) film configured in roll
transducer 352. The EPAM film may or may not be pre-strained.
[0099]
By way of example, FIG. 3A shows a cross-sectional view of an EP tube type pump 350, wherein a
tube of electroactive polymer is attached to rigid end structure 351 at both ends. This tube can
be made by winding EPAM or directly using a dip coating process. In a preferred embodiment,
the EP tube is axially stretched to axially impart a high prestrain. The predistortion force is
supported by a rigid rod 395 attached to the end structure on the outside or inside of the tube.
At high prestrain, the diameter of the tube shrinks in the middle due to Poisson contraction (not
shown in FIG. 3A). Two one-way (check) valves 316 are attached to the inner chamber of the
tube. Alternatively, the valve 316 can be a driven valve and can be switched at an appropriate
time.
[0100]
In certain embodiments, a tubular housing may be used instead of the rigid rod 359. A partial
vacuum is generated between the roll transducer 352 and the tubular housing to bias the roll
transducer 352 outwardly. In another embodiment, biasing material 352, such as a foam
material, may be used between the tubular housing and the roll transducer 352 to generate a
recovery force in the opposite direction to the direction in which the transducer extends.
[0101]
In FIG. 3B, when the EPAM is driven by applying a voltage, the EPAM film becomes thinner and
05-05-2019
33
stretches in the circumference (radially), thus more fluid 336 out of the one-way valve 316 Allow
one to flow into the inner chamber. In FIG. 3A, when the voltage is turned off, the EPAM film in
the transducer 352 contracts circumferentially, forcing fluid out through the other one-way valve
at higher pressures. Thus, the continuous application of voltage enables continuous pumping by
the tube pump device.
[0102]
The pump shown in FIGS. 3A and 3B is self-priming (draws a slight vacuum against the outside to
draw in fluid) as long as its thickness and tube geometry are set so that the EPAM does not
buckle. It can be. Alternatively, if a positive pressure fluid (relative to the outer surface of the
tube) is available, the positive pressure drives with circumferential pre-strain or pre-load. It can
be used for Or as noted above, bias pressure may be applied to the roll transducer by adding a
sealed enclosure around the roll transducer.
[0103]
The pumps 350 can be made in cascades or series (multistage) to further increase pressure (see
FIGS. 3I and 3J). For example, a relatively low pressure self-priming pump may be used to
provide positive pressure fluid to the second pump, which provides a higher pressure when
driven (typically 180 degrees out of phase with the first pump) Slipped). The multi-stage pump
may be comprised of end-to-end connected or stacked elements (see FIGS. 3I and 3J). Elements
can be cascaded by placing one element in the other (similar to nesting Russian dolls in each
other). The tubular pump elements may be arranged concentrically with one another. The
advantage of this internal or concentric cascade is that parts of a single element are not exposed
to the total pressure differential created by the pump.
[0104]
This embodiment provides easy fabrication of a large multi-layered EPAM pump, good coupling
of the EP drive and enables high pre-strain, which improves the performance of the EPAM
transducer. The pump can also be made naturally with the in-line pump tube shape with a good
filling geometry.
05-05-2019
34
[0105]
The pump of FIGS. 3A and 3B may be used in many applications, as well as other pump
embodiments described herein. For example, pump 350 may be used to pump fuel, such as
pumping fuel for fuel cells or fuel for combustion within the combustion chamber. This pump
may be used to move the fluid in the toy. For example, the pump can make the doll appear crying
by pumping fluid from the reservoir. The pump may be used in refrigeration applications or as
part of a thermal control system. The pump may be used for pharmaceutical applications such as
drug delivery. For example, in biological applications, the pump may be used to deliver insulin
and may include a sensor that measures blood glucose levels such that insulin is delivered in a
controlled manner. Other types of agents can be delivered in a controlled manner with
appropriate biological sensors that measure the biological parameter (s).
[0106]
In general, pumps may be used to transfer fluid from one enclosure (eg, conduit, well) to another,
generally from a low pressure enclosure to a high pressure enclosure. In other cases, the fluid
may be moved from a low potential energy location to a high potential energy location as the
water is pumped up for irrigation. In still other cases, the pump may be used to move the fluid
within an open or closed structure (eg, a pipe or irrigation canal).
[0107]
The tube geometry and basic structure described herein may also be used to drive other devices,
including, for example, linear actuators, hydraulic cylinders, and speakers. For example, FIGS. 3C
and 3D show an embodiment that integrates the basic pump structure described in FIGS. 3A and
3B for driving an internal hydraulic cylinder device 355. FIG. The hydraulic cylinder comprises a
cylinder between roll transducer 352, end structure 351 and end structure 351. The cylinder
359 and the guide bearing / seal 357 may be used to guide the output shaft 356 that fits within
the cylinder 359. The cylinder includes an opening that allows fluid 336 to flow into the cylinder.
Guide bearings / seals 357 allow the output shaft to move smoothly and allow fluid to remain in
the hydraulic cylinder. The hydraulic cylinder 355 may include a forced return mechanism 358,
such as a spring.
[0108]
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35
When a voltage is applied to the roll transducer of FIG. 3D, the roll transducer stretches 353 to
draw fluid 336 out of the cylinder 359 and the output shaft 356 is pulled downward. When the
voltage is removed from the roll transducer, the fluid moves into the cylinder and pushes the
output shaft upwards. The forcing mechanism 358 also provides a force to move the output shaft
356 upward. When the voltage to the roll transducer is off, the output shaft is fully extended as
shown in FIG. 3C. A hydraulic cylinder may be used to perform work on other objects via the
extension of the output shaft 356.
[0109]
FIG. 3E shows a second embodiment of an EPAM tube pump device. In this embodiment, the rigid
support rods of FIGS. 3A and 3B can be replaced with one or more springs to provide axial prestrain to the tube. The spring allows the tube to extend longitudinally when driven. In other
embodiments, a tube type pump device comprising an electroactive polymer roll transducer may
be used. EPAM roll transducers are described in some detail with respect to FIGS. 4A-4E and 4K4M. An EPAM roll transducer is also described in co-pending US patent application Ser. No. 10 /
154,449, filed May 21, 2002, entitled "Rolled Electroactive Polymers," which is incorporated by
reference above. It was incorporated.
[0110]
The pump or compressor based on the roll transducer 328 has appropriate hose connections at
both ends and has holes through its entire axis (FIG. 3E). As shown in FIG. 3E, the EPAM roll
transducer 328 can axially expand or contract upon application of a voltage, with its diameter
substantially unchanged. The internal volume thus increases linearly with tension. By attaching
the one-way valve 316 to either end of the tube, the change in volume provides fluid movement
across the check valve 316 and fluid is moved in one direction through the roll actuator 326.
This EPAM tube type pump device provides a simple and robust design of a small unit.
[0111]
FIG. 3F shows an embodiment of a diaphragm pressure pump 365. The movement of the
diaphragm in transducer 367 may be used to alternately draw fluid into the chamber and then
05-05-2019
36
expel it through the outlet tube via one way valve 316. The diaphragm type EPAM transducer
367 is described in detail in co-pending US patent application Ser. No. 09 / 619,846, filed on Jul.
20, 2000 entitled "Electroactive Polymer Devices", Was incorporated here.
[0112]
The six diaphragm transducers 367 can be mechanically biased by one of several different means
to influence the direction of deflection. For example, a spring loaded plunger may be used to bias
the diaphragm. In one embodiment, spring-type designs have been tested for low flow rates and
pressures. The flow was approximately 40 ml / min at 1 kPa (kilopascals) using a single layer
electroactive polymer. The pumps can be cascaded to increase the pressure above 2.5 kPa.
Spring type bias may be suitable for low power applications.
[0113]
Other methods of biasing the diaphragm type transducer include the use of a biasing material
397 such as foam material, pressure (or vacuum), and an expanding agent (eg, a small amount of
silicone oil). Various means of biasing the EPAM film can be found in "Electroactive Polymer
Devices", US patent application Ser. No. 09/619, filed on Jul. 20, 2000, "ELASTOMETRIC
DIFFERENCE POLYMER FILM SONIC ACTUATOR" No. 846, and "MONOLITHIC ELECTROACTIVE
POLYMERS" filed on Feb. 7, 2001, US Patent Application Serial No. 09 / 779,203, all of which
are incorporated herein by reference for all purposes. Be done.
[0114]
By way of example, FIG. 3F shows a cross-sectional view of a self-priming pump comprising an
EPAM diaphragm transducer 367 where the EPAM diaphragm is biased with the insertion of
open pore foam 397. The pump 365 comprises a screen 369 surrounded by a lower chamber
387, an upper chamber 398, a grid plate 369, six diaphragm transducers 367, three valves 316,
385 and 396, and a pump housing 366. Grid plate 369 includes an opening for receiving a
diaphragm. Screen 368 is used to hold the foam in place. In one embodiment, the foam can
extend to the bottom of the lower chamber 387 and a screen may not be used.
[0115]
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37
As the EPAM diaphragm in the transducer contracts, fluid is drawn into valve chamber 398
through valve 316 at inlet 342. The diaphragm is then extended with the drive, which allows
fluid to flow through the valve 385. Once pressure is stored in the area behind the diaphragm,
fluid can also be pushed through the outlet valve 386 and routed to the back stage (see FIGS. 3I
and 3J).
[0116]
One advantage of the configuration shown in FIG. 3F is self-priming (i.e., withdrawing fluid), and
the biasing means simply provides sufficient biasing force to draw fluid from the top input
chamber to the bottom outlet chamber through the one-way valve. It is self-priming that should
be supplied. Although the output stroke (contraction) of the electroactive polymer can supply
high output pressure or alternately high suction input pressure, the biasing means need not
supply a large biasing force.
[0117]
3G and 3H show an embodiment of an EPAM film pump 400. FIG. FIG. 3G shows a perspective
view of the pump 400 and FIG. 3H shows a cross section through the inlet 342 and the outlet
343. The pump 400 may include a clamp plate 401 (eg, 52 are shown in FIG. 3G) having a
plurality of openings 402, an EPAM film 370 which may be comprised of one or more layers, and
a lower chamber 371. The lower chamber may include an inlet 342, an outlet, check valves 403
and 404 that control the direction of flow, and fluid conduits leading to and from the pump
chamber 398. The pump chamber is formed by the lower chamber 371 and the recess at the top
of the EPAM film 370. Pump 400 may also include conditioning electronics and power supplies
not shown. The pumps shown in FIGS. 3G and 3H may use diaphragm biasing means known in
the art, and if the inlet pressure is higher than the outlet atmosphere diaphragm pressure, the
fluid itself may be used as the diaphragm bias.
[0118]
A fluid such as air enters lower chamber 371 through inlet 342. The fluid is acted upon by EPAM
film 370 (e.g. thermodynamic work is performed on the fluid) in pump chamber 398 and is
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38
pushed through the second opening in the lower chamber towards outlet 343. Clamp plate 401
determines the geometry of the active EPAM film. In the embodiment shown in FIGS. 3G and 3H,
there are 52 openings, each having a diameter of 0.375 inches (9.53 mm), resulting in a total
film active area of 5.74 inches <2> (3700 mm) It becomes <2>). There is a 1 mm gap between
the film and the bottom plate of the lower chamber to allow fluid to pass through the chamber.
The 1 mm gap is the height of the pump chamber when the EPAM film is flat. Larger gaps may
be used to extrude incompressible fluid, while smaller gaps minimize "dead space" when
extruding compressible fluid, and EPAM more efficiently pressurizes compressible fluid Make it
possible.
[0119]
In one embodiment, clamp plate 401 and lower chamber 371 are each approximately 0.375
inches high, and the total height of pump 400 is 0.75 inches. The clamp plate and lower chamber
are 4 inches long and 4 inches wide. Thus the footprint area of the pump device is 16 inches <2>.
In other embodiments, the total height may be increased or decreased from 0.75 inches and the
footprint area may be increased or decreased from 16 inches <2>. The clamp plate and lower
chamber may serve as a housing for the device, or the clamp plate and lower chamber may be
housed in separate housings.
[0120]
One advantage of diaphragm array pump 365 (FIG. 3F) or EPAM film pump 400 (FIGS. 3F and
3G) is that good pump efficiency can be obtained for fairly flat devices. One measure of the
flatness of the pump device is the ratio of its height divided by the product of the footprint area.
For a rectangular pump device, the footprint area is the product of device length and width. For
comparison purposes, a non-dimensional measure of flatness can be generated by normalizing by
the height of the device to obtain a flatness parameter equal to (height) <2> / (footprint area). For
a rectangular enclosure or enclosure, the footprint area is the product of the rectangular length
and width. For cubic shaped enclosures or enclosures, the flatness parameter yields a value of
one.
[0121]
In conventional pumps, the implementation requirements as a motor and as a pump mechanism
05-05-2019
39
can result in one or more flat parameters. In the present invention, the flatness parameter can be
much smaller than one. For example, for one embodiment of the EPAM film pump 400 of FIGS.
3G and 3H, the height of the device is 0.75 inches and the footprint area is 16 inches <2>. Thus,
the flatness parameter of this embodiment is approximately 0.035. Devices for performing the
thermodynamic work of the invention with flatness parameters much smaller than this value are
also possible, for example less than 0.1. For devices where space is very expensive, such as
electronic devices such as laptops, the ability to make devices that perform thermodynamic work
with small flatness parameters may be advantageous.
[0122]
In certain embodiments of the present invention, devices that perform thermodynamic work may
be used in microelectromechanical systems (MEMS). MEMS devices may be fabricated on a
substrate such as silicon. For these applications, the ability to fabricate devices that perform
thermodynamic work on fluids with small flatness parameters can be advantageous.
[0123]
Figures 31 and 3J illustrate an embodiment of a multi-stage EPAM compressor or pump device.
For all the embodiments described herein, multi-stage (multi-stage) pumps or compressors can
be assembled to have check valves between stages to increase the pressure after each stage. All
stages may be identical but in some cases the first stage may require mechanical biasing. In some
cases, different stages may be of different sizes, have different strokes, and may comprise
different layers of electroactive polymer film.
[0124]
In FIG. 3I, a planar configuration of linear stage compressor 380 is shown. Linear stage
compressor 380 includes three stages 381, 382, and 383, which are aligned in the same plane.
Multiple stages of compressors may be connected via one or more barb fittings, tubing (i.e., fluid
conduits), and check valves.
[0125]
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40
A fluid such as air may enter stage 381 and be pumped to a high pressure at each stage and
finally exit stage 383. Each stage is driven 180 degrees out of phase with the stage on either side
(i.e. upstream and downstream). In this way, when one stage is compressed, the fluid flows into
the subsequent (downstream) stage, which is a lower pressure. A check valve may be used to
prevent fluid flow to the previous upstream stage, such as from stage 382 to stage 381.
Generally, multiple stages can be used with the present invention, and the invention is not limited
to three stages.
[0126]
In FIG. 3J, the stack configuration of multi-stage pump 375 is shown. The multi-stage pump
includes three stages 376, 377 and 378, one stacked on top of the other. Stage groups may be
identical. The low flatness parameters for each stage possible with the pump of the present
invention may allow for stack configurations not possible with conventional pumps. Fluid flows
downward from the first stage 376 to stages 377 and 378 and then exits the exit of stage 378.
For best operation with multi-stage pumps, the timing of one stage's stroke is generally adjusted
relative to the next stage's stroke. For example, the compression stroke of one stage is matched
to the expansion stroke of the next stage. When a compressible fluid such as a gas is compressed
to a high pressure, the stroke volume of each stage is ideally matched to the changing volume of
the gas (eg if the gas is compressed and its source of the multistage pump The final stage only
needs to push roughly half the volume of the first stage per stroke if it is half the volume of the
[0127]
In the embodiments described above, electroactive polymer devices that perform thermodynamic
work on fluid may provide many advantages over conventional pump / compressor technology,
which may result in quieter operation (piston based System removal, and the use of small high
frequency actuators instead, operating at frequencies outside the human hearing range, lower
costs (inexpensive materials, equivalent design and simpler parts and less parts than equivalent
electric motor systems), And high efficiency included.
[0128]
Electroactive polymers can be scaled very well.
05-05-2019
41
That is, a large hydraulic actuator may be designed for heavy equipment, or a small radiator for
integrated circuits may be designed. The pressure required for a particular application (eg,
refrigeration or air conditioning) may be scaled up by increasing the number of layers of polymer
film per stage, and / or the number of stages. Unlike conventional motor driven pumps or
compressors, electroactive polymer pumps can be driven at frequencies above or below the
audible range. 3. Electroactive polymer device
[0129]
3.1 トランスデューサ
[0130]
4A-2E illustrate a rolled electroactive polymer device 20 according to an embodiment of the
present invention.
A wound electroactive polymer device can be used to drive an EPAM device that performs
thermodynamic work on a fluid, and a fluid conduit, or external or internal, used with a device
that performs thermodynamic work on a fluid It can function as part of another type of structure
immersed in the fluid field. A rolled electroactive polymer device may provide linear and / or
rotational / twisting motion to operate the EPAM device. See, for example, the fan embodiment of
FIG. 2H. 4A shows a side view of device 20. FIG. FIG. 4B shows an on-axis view of device 20 from
the top end. FIG. 4C shows an on-axis view of device 20 taken through cross section A-A. FIG. 4D
shows the elements of the device 20 prior to being wound. Device 20 comprises wound
electroactive polymer 22, spring 24, end pieces 27 and 28, and various manufacturing elements
that assemble device 20.
[0131]
As shown in FIG. 4C, the electroactive polymer 22 is rolled. In certain embodiments, a rolled
electroactive polymer is rolled with or without electrodes on its own (eg, as a poster), or wound
around another object (eg, a spring 24) Refers to an electroactive polymer. The polymer may be
repeatedly wound and may comprise at least a portion of the outer layer of polymer overlapping
at least in part of the inner layer of polymer. In one embodiment, a rolled electroactive polymer
refers to an electroactive polymer spirally wound around an object or center. The term wound as
used herein is independent of how the polymer achieves its wound configuration.
05-05-2019
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[0132]
As shown by FIGS. 4C and 4D, the electroactive polymer 22 may be wound around the outside of
the spring 24. The spring 24 provides a force to pull at least a portion of the polymer 22. The
upper end 24 a of the spring 24 is attached to a rigid end piece 27. Similarly, the upper end 24 b
of the spring 24 is attached to the rigid end piece 28. The top edge 22a of the polymer 22 (FIG.
4D) is wound around the end piece 27 and attached thereto using a suitable adhesive. The lower
edge 22b of the polymer 22 is wound around the end piece 28 and attached thereto using a
suitable adhesive. Thus, the upper end 24 a of the spring 24 is operatively coupled to the upper
edge 22 a of the polymer 22, and the deflection of the upper end 24 a corresponds to the
deflection of the upper edge 22 a of the polymer 22. Similarly, the lower end 24 b of the spring
24 is operatively coupled to the lower edge 22 b of the polymer 22, and the deflection of the
lower end 24 b corresponds to the deflection of the lower edge 22 b of the polymer 22. The
polymer 22 and the spring 24 can flex between their respective upper and lower portions.
[0133]
As mentioned above, many electroactive polymers perform better when prestrained. For example,
certain polymers exhibit higher breakdown field strength, electrically driven strain, and energy
density when prestrained. The spring 24 of the device 20 exerts a force on the polymer 22 to
cause circumferential and axial pre-strain.
[0134]
The spring 24 is a compression spring which axially stretches the polymer 22 and provides an
outward force in the opposite axial direction (FIG. 4A) which pulls the polymer 22 axially. Thus,
the spring 24 keeps the polymer 22 pulled in the axial direction 35. In one embodiment, polymer
22 has an axial prestrain in direction 35 of about 50 to about 300 percent. The device 20 may be
manufactured by winding a pre-strained electroactive polymer film around the spring 24 while
the spring is compressed, as described in more detail below for manufacturing. Once released,
the spring 24 maintains the polymer 22 in tension to achieve an axial prestrain.
[0135]
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43
Springs 24 also maintain circumferential pre-strain on polymer 22. The pre-strain may be
established in the polymer 22 in the longitudinal direction 33 (FIG. 4D) before the polymer is
wound around the spring 24. Techniques for establishing pre-strain in this direction during
manufacture are described in more detail below. Fixing or securing the polymer after being
wound, along with the substantially constant outer peripheral dimension for the spring 24,
maintains the circumferential pre-strain for the spring 24. In one embodiment, polymer 22 has a
circumferential prestrain of about 100 to about 500 percent. In most cases, the spring exerts a
force that generates an anisotropic prestrain on the polymer 22.
[0136]
End pieces 27 and 28 are attached to the opposite ends of rolled electroactive polymer 22 and
spring 24. FIG. 4E shows a side view of the end piece 27 according to an embodiment of the
present invention. The end piece 27 is a circular structure comprising an outer flange 27a, an
interface 27b and an inner hole 27c. The interface portion 27 b preferably has the same outer
diameter as the spring 24. The edge of interface portion 27b can also be rounded to prevent
damage to the polymer. The inner hole 27c is circular and passes through the center of the end
piece 27 from the upper end to the lower outer end including the outer flange 27a. In particular
embodiments, end piece 27 comprises aluminum, magnesium, or other mechanical metal. The
inner hole 27 c is defined by a hole machined or similarly manufactured in the end piece 27. In a
particular embodiment, the end piece 27 comprises a 1/2 inch end cap with a 3/8 inch inner
hole 27c.
[0137]
In one embodiment, the polymer 22 does not extend all the way to the outer flange 27a, leaving
a gap 29 between the outer portion edge of the polymer 22 and the inner surface of the outer
flange 27a. An adhesive or glue can be added to the wound electroactive polymer device to
maintain its rolled structure, as described in further detail below. The gap 29 provides a
dedicated space for the adhesive or glue on the end piece 27 instead of stacking to the outside
diameter of the rolled device, and all polymer layers in the roll are fixed to the end piece 27 To
make In particular embodiments, gap 29 is between about 0 mm and about 5 mm.
[0138]
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44
The portion of electroactive polymer 22 and spring 24 between end pieces 27 and 28 may be
considered active for its functional purpose. The end pieces 27 and 28 thus define the active area
32 (FIG. 4A) of the device 20. End pieces 27 and 28 provide a common structure for securing
with spring 24 and securing with polymer 22. In addition, each end piece 27 and 28 allows an
external mechanical and removable connection to the device 20. For example, device 20 may be
employed in a robotic application where end piece 27 is attached to the robot's upstream link
and end piece 28 is attached to the robot's downstream link. The drive of the electroactive
polymer 22 is then determined by the downstream link to the upstream link as determined by
the degree of freedom between the two links (e.g. rotation of link 2 around the pin joint on link
1). move.
[0139]
In a particular embodiment, the inner hole 27c comprises an internal thread that allows a screw
interface with a threaded member, such as a screw or a threaded bolt. The internal threads allow
removable mechanical fixation to one end of the device 20. For example, the screws may be
threaded on the inner threads in the endpiece 27 for external attachment to the robot element. A
nut or bolt, which is screwed into end pieces 27 and 28, respectively, for removable mechanical
fixation inside device 20, penetrates through the core of the shaft of spring 24, whereby the two
end pieces 27 and 28 are fixed to one another. This allows the device 20 to be held in any flexing
condition, such as a useful fully compressed condition while being rolled. This is also useful
during storage of the device 20 so that the polymer 22 is not distorted during storage.
[0140]
In one embodiment, a rigid member or linear guide 30 is disposed within the spring core of
spring 24. Because the polymer 22 in the spring 24 is substantially compliant between the end
pieces 27 and 28, the device 20 has an axial deflection along the direction 35 and from its linear
axis (the axis passing through the center of the spring 24) Allows both flexing of polymer 22 and
spring 24 away. In one embodiment, only axial deflection is desired. The linear guide 30 prevents
the device 20 from bending about the linear axis between the end pieces 27 and 28. Preferably,
the linear guide 30 does not interfere with the axial deflection of the device 20. For example, the
linear guide 30 preferably does not create a frictional resistance between itself and any part of
the spring 24. With the linear guide 30 or any other restraint that prevents movement other than
the axial direction 35, the device 20 can function as a linear actuator or generator with an output
05-05-2019
45
of exactly the direction 35. The linear guide 30 may be constructed of any suitably rigid material
such as wood, plastic, metal or the like.
[0141]
The polymer 22 is repeatedly wound around the spring 22. For a single electroactive polymer
layer configuration, the rolled electroactive polymer of the present invention may be comprised
between about 2 and about 200 layers. In this case, layer refers to the number of polymer films
or sheets that overlap in the radial cross section of the wound polymer. In some cases, a rolled
polymer is comprised between about 5 and about 100 layers. In certain embodiments, a rolled
electroactive polymer is comprised between about 15 and about 50 layers.
[0142]
In another embodiment, the rolled electroactive polymer employs a multilayer structure. The
multilayer layer structure comprises multiple polymer layers disposed on top of one another
before being rolled or wound. For example, a second electroactive polymer layer without
electrodes patterned thereon may be disposed on the electroactive polymer having electrodes
patterned on both sides. An electrode in direct contact between the two polymers functions on
both sides of the polymer surface in direct contact. After being rolled, the lower electrode of the
electroded polymer contacts the upper side of the polymer without the electrode. In this way, the
second electroactive polymer without electrodes patterned on it uses two electrodes on the first
electroactive polymer.
[0143]
Other multilayer structures are also possible. For example, the multilayer structure can comprise
any number of polymer layers, with odd numbered polymers being electroded and even
numbered polymers not being electroded. The upper upper surface of the electrodeless polymer,
after being wound, relies on the lower electrode of the laminate. Multilayer structures having 2,
4, 6, 8, etc. are possible with this technology. In some cases, the number of layers used in the
multilayer structure can be limited by the dimensions of the roll and the thickness of the polymer
layer. As the roll radius decreases, the number of acceptable layers typically decreases.
Regardless of the number of layers used, the wound transducer is configured such that an
electrode of a given polarity does not contact an electrode of the opposite polarity. In one
05-05-2019
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embodiment, the multilayer layers are each individually electroded, and every other polymer
layer is inverted prior to being wound, such that electrodes which contact each other after being
wound are the same voltage or polarity. Be done.
[0144]
Multilayer polymer laminates may also comprise more than one type of polymer. For example,
one or more second polymers may be used to alter the elasticity or stiffness of the rolled
electroactive polymer layer. The polymer may or may not be active to charge / discharge during
operation. When inactive polymer layers are employed, the number of polymer layers is odd. The
second polymer can also be another type of electroactive polymer that changes the performance
of the wound product.
[0145]
In certain embodiments, the outermost layer of the rolled electroactive polymer does not have an
electrode disposed thereon. This can be done to provide a layer of mechanical protection, or to
electrically isolate the electrodes on the inner layer in turn. For example, the inner and outer
layers and the surface coating may be selected to provide fluid compatibility as described above.
The multilayer layer properties described above may also be applied to unrolled electroactive
polymers such as the EPAM diaphragm described above.
[0146]
The device 20 provides a compact electroactive polymer device structure and improves the
overall electroactive polymer device performance over conventional electroactive polymer
devices. For example, the multilayer structure of device 20 adjusts the overall spring constant of
the device relative to each of the individual polymer layers. In addition, the increased stiffness of
the device achieved via the spring 24 increases the stiffness of the device 20, allowing for a
faster response in actuation if desired.
[0147]
05-05-2019
47
In a particular embodiment, the spring 24 is a compression spring such as Catalog No. 11422
provided by Century Spring of Los Angeles, California. The spring is characterized by a spring
force of 0.91 lb / inch and a free length of 4.38 inches, a tightness of 1.17 inches, an outer
diameter of 0.360 inches and an inner diameter of 0.3 inches. In this case, the rolled
electroactive polymer device 20 has a height 36 of about 5 to about 7 cm, a diameter 37 of about
0.8 to about 1.2 cm, and an active area between the end pieces of about 4 to about 5 cm. Have.
The polymer is characterized by a circumferential prestrain of about 300 to about 500 percent,
and an axial prestrain of about 150 to about 250 percent (including the contribution of force
from the spring 24).
[0148]
Device 20 is shown having a single spring 24 disposed inside a rolled polymer, but additional
structures such as other springs outside the polymer also provide strain and pre-strain forces It
can be used for These external structures may be attached to the device 20, for example using
end pieces 27 and 28.
[0149]
FIG. 4F illustrates a bending transducer 150 that provides variable stiffness based on structural
changes in accordance with an embodiment of the present invention. In this case, the transducer
150 changes and controls the stiffness in one direction using polymer deflection in the other
direction. In one embodiment, this device may use vanes in the fluid flow described with
reference to FIGS. 2K and 2L. Transducer 150 includes a polymer 151 secured by a rigid support
152 at one end. Attached to the polymer 151 is a flexible thin material 153 such as, for example,
polyimide or Mylar using an adhesive layer. The flexible thin material 153 has a modulus of
elasticity greater than the polymer 151. The difference in modulus of elasticity on the upper and
lower sides 156 and 157 of the transducer 150 bends the transducer when driven. Electrodes
154 and 155 are attached to the opposite side of the polymer 151 to provide electrical
communication between the polymer 151 and the control electronics used to control the
deflection of the transducer 150. Transducer 150 is not planar as shown, but rather is slightly
curved about axis 160. Direction 160 is defined as rotation or bending about a line extending
axially from rigid support 152 through polymer 151. This curvature causes the transducer 150
to be rigid in response to the force applied to the tip along any of the directions indicated by the
arrows 161. Instead of or in addition to force, torque may be applied to the transducer. These
torques are given for the axes indicated by the arrows in directions 161a and 161b.
05-05-2019
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[0150]
FIG. 4G shows a transducer 150 with a deflection in direction 161 b generated by applying a
voltage to electrodes 154 and 155. This voltage is applied to allow the bending force to
overcome the resistance exhibited by the undriven curvature. Effectively, the transducer 152
bends with the kink caused by the initial curvature. In this state, the stiffness in response to the
force or torque indicated by direction 161 is much less.
[0151]
A mechanical interface may be attached to distal end 159 of transducer 150. Alternatively,
mechanical attachment can be made to the flexible thin material 153 to allow the transducer 150
to be implemented in a mechanical device. For example, the transducer 150 is suitable for use in
applications such as lightweight space structures where it is useful to fold the structure so that it
can be stored or deployed. In this example, the stiffness conditions of the individual transducers
(forming the ribs in the structure) occur when the structure is deployed. The transducers can be
driven and the ribs can be folded to allow storage. In other applications, the transducer may form
a rib in the sidewall of the pneumatic tire. In this application, changes in rib stiffness can affect
tire stiffness and thus affect the resulting handling of the car using the tire. Similarly, the device
can be implemented in a shoe, and changes in rib stiffness can affect the shoe stiffness.
[0152]
Transducer 150 provides one example where actuation of the electroactive polymer causes a low
energy change in the configuration or shape that affects the stiffness of the device. Using this
technique, it is actually possible to use the transducer 150 to change the stiffness at a level
greater than direct mechanical or electrical energy control. In another embodiment, the
deflection of the electroactive polymer transducer directly contributes to changing the stiffness
of the device in which the transducer is incorporated.
[0153]
FIG. 4H shows a bow device 200 providing variable stiffness, according to another embodiment
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of the present invention. Bow device 200 is a planar arrangement comprising a flexible frame
202 attached to a polymer 206. Frame 202 includes six rigid members 204 pivotally connected
at joints 205. Member 204 and joint 205 couple the deflection of the polymer in planar direction
208 to the mechanical output in orthogonal planar direction 210. Bow device 200 is in the
resting position shown in FIG. 4H. Attached to the opposite (top and bottom) surfaces of the
polymer 206 is an electrode 207 (bottom electrode on the bottom side of the polymer 206 is not
shown) and provides electrical communication with the polymer 206. FIG. 4I shows the bow
device 200 after actuation.
[0154]
In the rest position of FIG. 4H, rigid member 204 provides greater rigidity to force 209 in
direction 208 due to the rigidity of its material. However, for the position of the bow device 200
shown in FIG. 4I, the stiffness in the direction 208 is based on the compliance of the polymer
202 and any rotational elastic resistance provided by the joint 205. Thus, the control electronics
in electrical communication with the electrodes 207 have the deflection of the polymer 206
shown in FIG. 4H and the corresponding electrical conditions to provide the corresponding high
stiffness, and the deflection of the polymer 206 shown in FIG. 4I, And may be used to provide an
electrical condition that provides a corresponding low stiffness. In this, simple on / off control
may be used to provide a large stiffness change using device 200.
[0155]
In addition to the stiffness change achieved by changing the configuration of the rigid members
in device 200, the stiffness for the position in FIG. 4I is given by January 16, 2002 by Kornbluh
et al. Entitled "Variable Stiffness Electroactive Polymers". The application can be further modified
using one of the open or closed loop stiffness techniques described in detail in co-pending US
patent application Ser. Incorporated herein by reference for the purpose of
[0156]
3.2 Multiple Active Areas
[0157]
In some cases, the electrodes cover a limited portion of the electroactive polymer rather than the
entire area of the polymer.
05-05-2019
50
This is to prevent the electrical breakdown around the edge of the polymer, to allow the polymer
part to promote the wound configuration (eg outer polymer barrier layer), to provide
multifunctionality, or one of the polymers It may be done to achieve customized deflection for
one or more parts.
As used herein, active area is defined as a portion of an electroactive polymer, and a portion of a
transducer comprising one or more electrodes that provide or receive electrical energy to or
from that portion. The active area may be used for any of the functions described below. For
actuation, the active area comprises a portion of the polymer that has sufficient electrostatic
force to allow deflection of that portion. For power generation or detection, the active area
comprises a portion of the polymer that has sufficient deflection to allow for changes in
electrostatic energy. The polymers of the present invention may have multiple active areas.
[0158]
According to the invention, the term "monolithic" is used herein to refer to a transducer
comprising an electroactive polymer and a plurality of active areas on a single polymer. FIG. 4J
illustrates a monolithic transducer 150 with multiple active areas on a single polymer 151
according to one embodiment of the present invention. The monolithic transducer 150 converts
between electrical energy and mechanical energy. Monolithic transducer 150 comprises an
electroactive polymer 151 having two active areas 152a and 152b. The polymer 151 can be held
in place using, for example, a rigid frame (not shown) attached to the edge of the polymer.
Coupled to the active areas 152a and 152b is a wire 153 that enables electrical communication
between the active areas 152a and 152b and allows electrical communication with the
communication electronics 155.
[0159]
Active region 152a has upper and lower electrodes 154a and 154b attached to polymer 151 on
its upper and lower surfaces 151c and 151d, respectively. Electrodes 154 a and 154 b provide
and receive electrical energy across portion 151 a of polymer 151. Portion 151a may flex due to
changes in the electric field provided by electrodes 154a and 154b. For actuation, portion 151a
is a polymer 151 between electrodes 154a and 154b, and any other polymer 151 having
sufficient electrostatic force to allow deflection upon application of a voltage using electrodes
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154a and 154b. Equipped with parts. When active region 152a is used as a generator to convert
electrical energy to mechanical energy, the deflection of portion 151a causes a change in the
electric field in portion 151a, which is received as a potential difference by electrodes 154a and
154b.
[0160]
Active region 152b has upper and lower electrodes 156a and 156b attached to polymer 151 on
its upper and lower surfaces 151c and 151d, respectively. Electrodes 156 a and 156 b provide
and receive electrical energy across portion 151 b of polymer 151. Portion 151b may flex due to
changes in the electric field provided by electrodes 156a and 156b. For actuation, portion 151b
comprises polymer 151 between electrodes 156a and 156b and any other polymer 151 having
sufficient electrostatic force to allow deflection upon application of a voltage using electrodes
156a and 156b. Equipped with parts. When active region 152b is used as a generator to convert
electrical energy to mechanical energy, the deflection of portion 151b produces a change in the
electric field in portion 151b, which is received as a potential difference by electrodes 156a and
156b.
[0161]
The active area of the electroactive polymer can be easily patterned and configured using
conventional electroactive polymer electrode fabrication techniques. Multiple active area
polymers and transducers are further described in 09/779, 203, which is incorporated herein by
reference for all purposes. With the ability to pattern and independently control multiple active
areas, the wound transducer of the present invention can be employed in many new applications
while being adopted in new ways in existing applications.
[0162]
FIG. 4K shows a monolithic transducer 170 with multiple active areas on a single polymer 172,
prior to being rolled, according to an embodiment of the present invention. In the present
invention, the monolithic transducer 170 may be utilized in a wound or unwound configuration.
Transducer 170 comprises discrete electrodes 174 on opposing polymer sides 177. The opposite
side (not shown) of the polymer 172 may include individual electrodes corresponding to the
location of the electrodes 174, or function on multiples or all of the electrodes 174 across the
05-05-2019
52
area to simplify electrical communication Common electrode. The active area 176 then
comprises the portion of the polymer 172 between the respective individual electrode 174 and
the electrode on the opposite side of the polymer 172, which is determined by the operating
mode of the active area. For example, when actuated, the active area 176a of the electrode 174a
includes a portion of the polymer 172 that has sufficient electrostatic force to allow for
deflection of that portion as described above.
[0163]
Active area 176 on transducer 170 may be configured for one or more functions. In one
embodiment, all active areas 176 are configured for driving. In other embodiments suitable for
use in robotic applications, one or more active areas 176 are configured to detect while active
area 176 is configured for actuation. In this way, a rolled electroactive polymer device using
transducer 170 is capable of both actuation and detection. Any active area designated for
detection may include dedicated wiring to the detection electronics described below.
[0164]
As shown, the electrodes 174a-d each include wires 175a-d attached thereto that provide
dedicated external electrical communication and allow individual control for the respective active
areas 176a-d. The electrodes 174e-i are all electrical communication with the common electrode
177 and the wires 179 in common electrical communication with the active areas 176e-i. The
common electrode 177 simplifies electrical communication with the plurality of active areas of
the rolled electroactive polymer that are employed to operate similarly. In one embodiment, the
common electrode 177 comprises an aluminum foil disposed on the polymer 172 prior to being
wound. In one embodiment, common electrode 177 is a patterned electrode of a material similar
to that used for electrodes 174a-i, such as carbon grease.
[0165]
For example, a set of active areas may be employed for one or more of driving, generating,
detecting, changing stiffness and / or braking, or a combination thereof. Proper electrical control
also allows a single active area to be used for more than one function. For example, active area
174a may be used for actuation of fluid conduits and variable stiffness control. The same active
area may also be used for power generation to make electrical energy based on movement of the
05-05-2019
53
fluid conduit. The appropriate electronics for each of these functions will be described in more
detail later. Active area 174b may also be used flexibly for driving, generating, detecting,
changing stiffness, or a combination thereof. Energy generated by one active area may be
provided to another active area, if desired for the application. Thus, the wound polymer and
transducer of the present invention control actuators converting electricity to mechanical energy,
generators converting mechanical to electrical energy, sensors detecting parameters, or stiffness
and / or braking, or combinations thereof Can include an active area used as a variable stiffness
and / or braking device used to
[0166]
In one embodiment, a plurality of active areas employed for driving are wired in groups to
provide gradual electrical control of force and / or deflection output from a rolled electroactive
polymer device. For example, a rolled electroactive polymer transducer may have fifty active
areas, where twenty active areas are coupled to one common electrode, ten active areas are
coupled to a second common electrode, and ten more. The active area may be coupled to the
third common electrode, five active areas may be coupled to the fourth common electrode, and
the remaining five may be individually wired. Appropriate computer management and on-off
control for each common electrode then allow step-wise force and deflection control for the
wound transducer using binary on-off switching. The biological analog of this system is the
motor unit found in many mammalian muscle control systems. Clearly, any number of active
areas and common electrodes may be realized in this way to provide a suitable mechanical
output or staged control system.
[0167]
3.3 Multiple Degrees of Freedom Device
[0168]
In another embodiment, a plurality of active areas are disposed on the electroactive polymer, and
subsets of such active areas are radially aligned after being wound.
For example, a plurality of active areas may be placed every 90 degrees in a roll after being
wound. These radially aligned electrodes can then be driven in unison to allow multiple degrees
of freedom of motion for the rolled electroactive polymer device. Similarly, multiple degrees of
05-05-2019
54
freedom of movement may be obtained for unrolled electroactive polymer devices, such as those
described for FIGS. 4F and 4G. Thus, a wound polymer device is one embodiment of multiple
degrees of freedom that can be obtained with the transducer configuration of the present
invention.
[0169]
FIG. 4L illustrates a possible wound transducer 180 of a two dimensional output in accordance
with an embodiment of the present invention. The transducer 180 comprises an electroactive
polymer 182 that is rolled up to provide ten layers. Each layer comprises four radially aligned
active areas. The center of each active area is arranged in 90 degree increments relative to its
neighbors. FIG. 4L shows the outermost layer of polymer 182 and radially aligned active areas
184, 186, and 188, which are arranged such that their centers exhibit 90 degree increments
relative to one another. The fourth radially aligned active area (not shown) on the back side of
the polymer 182 has a center located approximately 180 degrees away from the radially aligned
active area 186.
[0170]
The radially aligned active area 184 may include electrical communication in common with the
active area on the inner polymer layer having the same radial alignment. Similarly, the other
three radially aligned outer active areas 182, 186 and the back active area not shown may also
include common electrical communication with their corresponding inner layers. In one
embodiment, the transducer 180 comprises four leads that provide a common drive for each of
the four radially aligned sets of active areas.
[0171]
FIG. 4M shows a transducer 180 having a driven radially aligned active area 188 and its
corresponding radially aligned inner layer active area. The activation of the active area 188 and
the corresponding inner layer active area causes axial extension of the transducer 188 opposite
the polymer 182. The result is a horizontal bending of the transducer 180 approximately 180
degrees from the center point of the active area 188. This effect may be measured by the
deflection of the upper portion 189 of the transducer 180, which describes a radial arc from the
rest position shown in FIG. 4L to its position shown in FIG. 4M. Varying the amount of electrical
05-05-2019
55
energy provided to the active area 188 and the corresponding inner layer active area controls
the deflection of the upper portion 189 along this arc. Thus, the top portion 189 of the
transducer 180 can have the deflection shown in FIG. 4L, or a greater deflection, or a deflection
minimally away from the position shown in FIG. 4L. Similarly, bending in the other direction may
be achieved by driving one of the other radially aligned set of active areas.
[0172]
Combining the driving of the set of radially aligned active areas creates a two dimensional space
for deflection of the upper portion 189. For example, the radially aligned sets of active areas 186
and 184 may be simultaneously driven to create deflection at the top at a 45 degree angle
corresponding to the coordinate system shown in FIG. 4L. Reducing the amount of electrical
energy provided to the set 186 of radially aligned active areas and increasing the amount of
electrical energy provided to the set 184 of radially aligned active areas results in the upper
portion 189 being at zero degrees. Move closer to the mark. Proper electrical control then allows
the upper portion 189 to draw a path of any angle from 0 to 360 degrees, or to follow variable
paths in this two dimensional space.
[0173]
Transducer 180 is also capable of three-dimensional deflection. Simultaneous actuation of the
active areas on the four sides of the transducer 180 causes the upper portion 189 to move
upward. In other words, transducer 180 is also a linear actuator that is capable of axial deflection
based on simultaneous actuation of the active area on all sides of transducer 180. Combining this
linear drive with the differential drive of the radially aligned active areas and their resulting twodimensional deflections just mentioned creates a three-dimensional deflection space on top of the
transducer 180. Thus, proper electrical control allows the upper portion 189 to move both up
and down while drawing a two dimensional path along this linear axis.
[0174]
Although transducer 180 is only shown as a set of four radially aligned active areas arranged in
90 degree increments for simplicity, the transducer of the present invention capable of two and
three dimensional motion is more It will be appreciated that complex alternative designs may be
provided. For example, a set of eight radially aligned active areas arranged in 45 degree
05-05-2019
56
increments. Alternatively, a set of three radially aligned active areas arranged in 120 degree
increments may be suitable for 2D and 3D motion.
[0175]
In addition, although the transducer 180 is shown with only one set of axial active areas, the
structure of FIG. 4L is modular. In other words, a set of four radially aligned active areas
arranged in 90 degree increments may appear multiple times in the axial direction. For example,
a set of radially aligned active areas that allow two and three dimensional motion may be
repeated ten times to provide a waveform pattern that may be added to the fluid flow.
[0176]
4. detection
[0177]
The electroactive polymers of the present invention may also be configured as sensors. In
general, the electroactive polymer sensors of the present invention may detect "parameters" and
/ or changes in parameters. These parameters include temperature, density, strain, deformation,
velocity, position, contact, acceleration, vibration, volume, pressure, mass, opacity, concentration,
chemical state, conductivity, magnetization, dielectric constant, size, etc. , Is largely the physical
characteristics of the object. In some cases, detected parameters are associated with physical
"events". The physical event detected may be the attainment of a particular value or state of
physical or chemical properties. In biological systems, physical properties can be biological
parameters of the system, such as blood glucose levels or drug concentrations in the human
circulatory system.
[0178]
The electroactive polymer sensor is configured to deflect a portion of the electroactive polymer
in response to a change in the parameter being detected. The electrical energy state and
deflection state of the polymer are relevant. The change in electrical energy or the change in
05-05-2019
57
electrical impedance of the active area resulting from the deflection can then be detected by
detection electronics in electrical communication with the active area electrodes. This change
may constitute a change in polymer capacitance, a change in polymer resistance, and / or a
change in electrode resistance, or a combination of these. An electronic circuit in electrical
communication with the electrodes detects changes in electrical characteristics. If, for example,
changes in the capacitance or resistance of the transducer are measured, electrical energy will be
applied to the electrodes contained in the transducer to observe changes in the electrical
parameters.
[0179]
In one embodiment, deflection is input to the active area sensor in one way or more through one
or more coupling mechanisms. Certain embodiments and changing properties or parameters
measured by the sensor correspond to changing properties of the electroactive polymer, such as
displacement or size change in the polymer, and no bonding mechanism is used. Detection
electronics in electrical communication with the electrodes detect changes output by the active
area. In some cases, a logic device in electrical communication with the sensor's detection
electronics provides digital or other measurements of the detected changing parameter by
quantifying its electrical changes. For example, the logic device may be a single chip computer or
microprocessor that processes the information produced by the detection electronics.
Electroactive polymer sensors are further described in 10/007, 705, which is hereby
incorporated by reference for all purposes.
[0180]
The active area may be configured to perform detection upon actuation of the active area. For
monolithic transducers, one active area may be responsible for driving and the other area may be
responsible for detection. Alternatively, the same active area of the polymer is responsible for
driving and detection. In this case, a low amplitude, high frequency AC (detection) signal may be
superimposed on the drive signal. For example, a 1000 Hz detection signal may be superimposed
on a 10 Hz drive signal. The drive signal depends on the application, or how fast the actuator
moves, although drive signals ranging from less than 0.1 Hz to about 1 MHz are suitable for
many applications. In one embodiment, the detection signal is at least about 10 times faster than
the detected motion. The detection electronics then enable sensor performance without affecting
the polymer drive by detecting and measuring the high frequency response of the polymer.
Similarly, if an electroactive polymer transducer is also used as a generator, small high frequency
AC signals can be superimposed on the low frequency generated voltage signal if impedance
05-05-2019
58
changes are detected and measured. Then filtering techniques can separate the measurements
and the power signal.
[0181]
The active area of the present invention may also be configured to provide variable stiffness and
damping functions. In one embodiment, open loop technology is used to control the stiffness and
/ or damping of devices employing electroactive polymer transducers, thereby providing a simple
to achieve the desired stiffness and / or damping performance without sensor feedback. Design
can be provided. For example, control circuitry in electrical communication with the electrodes of
the transducer may supply a substantially constant charge to the electrodes. Alternatively, the
control circuit may supply a substantially constant voltage to the electrodes. Systems employing
electroactive polymer transducers provide several techniques for providing stiffness and / or
braking control. An exemplary circuit providing stiffness / braking control is shown below.
[0182]
Although details are not described, it is important to note that the active areas and transducers in
all drawings and descriptions of the present invention can be bi-directionally converted (with
appropriate electronic circuitry) between electrical energy and mechanical energy. It is. Thus,
wound polymers, active areas, polymer configurations, transducers, and any of the devices
described herein convert mechanical energy into electrical energy (power generation, variable
stiffness or damping, or detection), or electrical energy Can be a transducer that converts (drives,
varies stiffness or dampens, or detects) into mechanical energy. Typically, the generator or
sensor active area of the present invention comprises the polymer configured in such a way as to
produce a change in the electric field in response to the deflection of a portion of the polymer.
Changes in the electric field, along with changes in polymer dimensions in the direction of the
electric field, produce changes in voltage, thus producing changes in electrical energy.
[0183]
Often, transducers are employed in devices comprising other structures and / or functional
elements. For example, external mechanical energy may be input to the transducer in one way or
more via one or more mechanical transmission coupling mechanisms. For example, the transfer
mechanism receives mechanical energy generated by the flow and transmits a portion of the
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mechanical energy generated by the flow to a portion of the polymer, where the mechanical
energy generated by the flow is of the transducer It may be designed or configured to cause
deflection. The mechanical energy generated by the flow can create an inertial or direct force,
where part of the inertial force or part of the direct force is received by the transfer mechanism.
[0184]
5. Adjustment electronics
[0185]
The device of the present invention also relies on conditioning electronics to supply or receive
electrical energy from the electrodes of the active area for one of the electroactive polymer
functions described above. Conditioning electronics in electrical communication with the one or
more active areas may include functions such as stiffness control, energy consumption, electrical
energy generation, polymer actuation, polymer deflection detection, control logic, and the like.
[0186]
For driving, an electronic driver can be connected to the electrodes. The voltage supplied to the
electrodes of the active area depends on the particulars of the application. In one embodiment,
the active region of the present invention is electrically driven by modulating the applied voltage
around the DC bias voltage. Modulation around the DC bias voltage allows for improved
sensitivity and linearity of the transducer to the applied voltage. For example, transducers used in
audio applications may be driven by a 200 to 100 volt peak-to-peak signal on a bias voltage
ranging from about 750 to 2000 volts DC.
[0187]
Suitable drive voltages for the electroactive polymer, or portions thereof, may vary based on the
material properties of the electroactive polymer, such as the dielectric constant, as well as the
dimensions of the polymer, such as the thickness of the polymer film. For example, the drive field
used to drive the polymer 12 in FIG. 2A ranges from about 0 V / m to about 440 MV / m. Drive
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fields in this range can create pressures in the range of about 0 Pa to about 10 MPa. In order for
the transducer to create more force, the thickness of the polymer layer must be increased. The
drive voltage for a particular polymer can be reduced, for example, by increasing the dielectric
constant, reducing the polymer thickness, and reducing the elastic modulus.
[0188]
FIG. 4N shows an electrical block diagram of an open loop variable stiffness / braking system
according to an embodiment of the present invention. The system 130 comprises an
electroactive polymer transducer 132, a voltage source 134, control electronics comprising a
variable stiffness / brake circuit 136 and an open loop control 138, and a buffer capacitor 140.
[0189]
Voltage source 134 provides the voltage used in system 130. In this case, voltage source 134
sets the minimum voltage for transducer 132. Adjusting this minimum voltage in conjunction
with open loop control 138 adjusts the stiffness provided by transducer 132. Voltage source 134
also provides charge to system 130. Voltage source 134 may include a commercially available
voltage source such as a low voltage battery that provides a voltage in the range of about 1-15
volts, and a step-up circuit that boosts the voltage of the battery. In this case, the voltage stepdown performed by the step-down circuit in electrical communication with the electrodes of
transducer 132 may be used to adjust the electrical output voltage from transducer 132.
Alternatively, voltage source 134 may include a variable step-up circuit that can produce a
variable high voltage output from the battery. As described in more detail below, voltage source
134 may be used to apply a threshold electric field, described below, to operate the polymer in a
particular rigid region.
[0190]
The desired stiffness or damping of system 130 is controlled by variable stiffness / damping
circuit 136, which is provided by transducer 132 by setting and changing the electrical state
provided by the control electronics within system 130. Provides stiffness / braking of In this
case, the stiffness / braking circuit 36 inputs the desired voltage into the voltage source 134 and
/ or inputs parameters into the open loop control 138. Alternatively, if a step-up circuit is used to
boost voltage source 134, circuit 136 may input a signal to the step-up circuit to enable voltage
05-05-2019
61
control.
[0191]
When the transducer 132 flexes, the changing voltage causes charge to move between the
transducer 132 and the buffer capacitor 140. Thus, for example, from an oscillating mechanical
interface, expansion and contraction of the externally induced transducer 132 causes charge to
move back and forth between the transducer 132 and the buffer capacitor 140 through the open
loop control 138. The rate and amount of charge moved to or from the transducer 132 may
depend on the characteristics of the buffer capacitor 140, the voltage applied to the transducer
132, any other electrical element in the electrical circuit (when current passes therethrough)
Depending on the mechanical configuration of the transducer 132 and the force applied to or by
the transducer 132, such as the resistance used as open loop control 138 to provide
functionality. In one embodiment, the buffer capacitor 140 has a voltage substantially equal to
that of the transducer 132, the voltage of the system 130 is set by the voltage source 134, and
the open loop control 138 is a wire, when the transducer 132 is flexed. A substantially free
charge flow occurs between the transducer 132 and the buffer capacitor 140.
[0192]
The open loop control 138 provides a passive (without external energy supplied) dynamic
response for the stiffness provided by the transducer 132. That is, the stiffness provided by the
transducer 132 is set by electrical elements contained within the system 130, such as control
electronics and voltage source 134, or by signals from the control circuit 136 acting on one of
the electrical elements. I see. In either case, the response of transducer 132 is passive to the
external mechanical deflection imparted to it. In one embodiment, open loop control 138 is a
resistor. The resistance value of the resistance may be set to provide an RC time constant for a
time of interest, such as, for example, the period of vibration in the mechanical system in which
the transducer is implemented. In one embodiment, the resistor has a high resistance such that
the RC time constants of the open loop control 138 and the transducer 132 connected in series
are long relative to the frequency of interest. In this case, the transducer 132 has a substantially
constant charge for a time of interest. For some applications, a resistance in the range of about 5
to about 30 times the period of the frequency of interest and a resistance that creates an RC time
constant of the transducer may be appropriate. For applications involving cyclic motion,
increasing the RC time constant much greater than the mechanical period of interest means that
the amount of charge on the electrodes of the transducer 132 remains substantially constant
during one cycle. Make it possible. In the case where the transducer is used for damping, a
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62
resistance in the range of about 0.1 to about 4 times the period of the frequency of interest and a
resistor that makes up the RC time constant of the transducer may be appropriate. Those skilled
in the art will appreciate that the resistance value used for the resistance may vary based on the
application, particularly for the frequency of interest and the size of the transducer 132 (and
thus the capacitance C).
[0193]
In embodiments with appropriate electrical conditions used to control stiffness and / or damping
using open loop techniques, the control electronics may have electrical inaccuracies or circuit
effects that have minimal impact on current flow. A substantially constant charge is applied to
the electrodes of the transducer 132, except for those coming from the details. The substantially
constant charge leads to the increased stiffness of the polymer that resists deflection of the
transducer 132. One electrical configuration that achieves a substantially constant charge is one
that has a high RC time constant as described above. When the open loop control 138 and the RC
time constant values of the transducer 132 are long relative to the frequency of interest, the
charge on the electrodes of the transducer 132 is substantially constant. A further description of
stiffness and / or braking control is further described in commonly owned patent application 10
/ 053,511, which is incorporated herein by reference for all purposes.
[0194]
For power generation, mechanical energy may be applied to the polymer or active area in a
manner that allows changes in electrical energy to be removed from the electrode in contact with
the polymer. Many methods of applying mechanical energy and removing electrical energy
changes from the active area are possible. Rolled devices may be designed to utilize one or more
of these methods to receive electrical energy changes. For generation and detection, the
generation and utilization of electrical energy requires some type of conditioning electronics. For
example, at least a minimal amount of circuitry is required to remove electrical energy from the
active area. As yet another example, circuits with varying degrees of complexity may be used to
increase the efficiency or amount of electricity generation in a particular active area, or to
convert the output voltage to more useful values.
[0195]
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FIG. 5A is a block diagram of one or more active areas 600 on a transducer connected to power
conditioning electronics 610. The essential functions that may be performed by the power
conditioning electronics 610 include, but are not limited to: 1) voltage step up performed by the
step up circuit 602 that may be used when applying a voltage to the active area 600, 2) Charge
control implemented by charge control circuit 604, which may be used to add or remove charge
from active area 600 at a particular time, 3) by step-down circuit 608, which may be used to
adjust the electrical output voltage to the transducer It may include an implemented voltage step
down implemented. All of these functions may not be required in the conditioning electronics
610. For example, some transducer devices may not use the step-up circuit 602, other transducer
devices may not use the step-down circuit 608, or some transducer devices may use the step-up
circuit and the step-down circuit It may not be used. Also, some circuit functions can be
integrated. For example, one integrated circuit may perform the functions of both step-up circuit
602 and charge control circuit 608.
[0196]
FIG. 5B is a circuit block diagram of a rolled device 603 that employs a transducer 600 in
accordance with an embodiment of the present invention. As mentioned above, the transducer of
the present invention can behave electrically as a variable capacitor. To understand the operation
of transducer 603, the operating parameters of wound transducer 603 at two times t1 and t2
can be compared. While not wishing to be bound by any particular theory, many theoretical
relationships regarding the electrical performance of generator 603 are developed. These
relationships are not intended to limit the manner in which the described devices are operated,
but are provided for illustrative purposes only.
[0197]
At a first time t1, the wound transducer 600 has a capacitance C1, and the voltage between the
transducers 600 can be a voltage 601, VB. The voltage 601, VB may be provided by the step up
circuit 602. At a second time t2 after time t1, the transducer 600 can have a capacitance C2 that
is lower than the capacitance C1. Generally speaking, higher capacitance C1 occurs when
polymer transducer 600 is stretched in area, and lower capacitance C2 occurs when polymer
transducer 600 is contracted or relaxed in area. While not wishing to be bound by any particular
theory, the change in capacitance of a polymer film with electrodes can be estimated by wellknown formulas that relate capacitance to the area, thickness, and dielectric constant of the film.
05-05-2019
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[0198]
The decrease in capacitance of transducer 600 between t1 and t2 increases the voltage between
transducers 600. The increased voltage may be used to drive the current through the diode 616.
Diode 615 may be used to prevent charge backflow to the step up circuit at such time. The two
diodes 615 and 616 function as charge control circuit 604 for the transducer 600, which is part
of the power conditioning electronics 610 (see FIG. 5A). Depending on the configuration of
generator 603 and one or more transducers 600, more complex charge control circuits may be
developed, which are not limited to the design of FIG. 5B.
[0199]
The transducer may also be used as an electroactive polymer sensor to measure changes in the
parameter of the object to be detected. Typically, parameter changes induce deflection in the
transducer, which translates into electrical changes output by the electrodes attached to the
transducer. Many methods of providing mechanical or electrical energy to deflect the polymer
are possible. Typically, detection of electrical energy from the transducer uses some electronic
circuitry. For example, a minimal amount of circuitry is required to detect changes in electrical
conditions between the electrodes.
[0200]
FIG. 6 is a block diagram of a sensor 450 employing a transducer 451 according to one
embodiment of the present invention. As shown in FIG. 7, the sensor 450 comprises a transducer
451 and various electronic circuitry 455 in electrical communication with the electrodes
contained in the transducer 451. Electronic circuitry 455 is designed or configured to add,
remove, and / or detect electrical energy from transducer 451. Although many of the elements of
electronic circuit 455 are described as discrete units, it will be understood that some circuit
functions may be integrated. For example, one integrated circuit may perform the functions of
both logic device 465 and charge control circuit 457.
[0201]
In one embodiment, the transducer 451 prepares for detection initially by applying a voltage
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between its electrodes. In this case, voltage VI is provided by voltage 452. In general, voltage VI
is less than the voltage required to drive transducer 451. In one embodiment, the low voltage
battery may provide a voltage VI in the range of about 1-15 volts. In certain embodiments, the
choice of voltage VI is such as polymer dielectric constant, polymer size, polymer thickness,
environmental noise, and electromagnetic interference, compatibility with electronic circuitry
that may use or process sensor information, and much more Depends on the factor of Initial
charge is provided on the transducer 451 using the electronic control subcircuit 457. Electronic
control subcircuit 457 may typically include logic devices for performing voltage and / or charge
control functions to transducer 451, such as a single chip computer or microprocessor.
Electronic control subcircuit 457 is then responsible for changing the voltage provided by
voltage 452 to initially apply a relatively low voltage to transducer 451.
[0202]
Detection electronics 460 are in electrical communication with the electrodes of transducer 451
to detect changes in the electrical energy or characteristics of transducer 451. In addition to
detection, detection electronics 460 may include circuitry configured to detect, measure, process,
communicate, and / or record changes in the electrical energy or characteristics of transducer
451. The electroactive polymer transducer of the present invention can behave electrically to
respond to deflection of the electroactive polymer transducer in some manner. Thus, many
simple electrical measurement circuits and systems may be implemented in the measurement
electronics 460 to detect changes in the electrical energy of the transducer 451. For example, if
the transducer 451 operates in capacitance mode, a simple capacitance bridge may be used to
detect changes in the capacitance of the transducer 451. In another embodiment, a high
resistance resistor is placed in series with the transducer 451 and the voltage drop across the
high resistance resistor is measured as the transducer 451 deflects. More specifically, the change
in voltage of transducer 451 induced by the deflection of the electroactive polymer is used to
drive the current through the high resistance resistor. The polarity of the voltage change across
the resistor then determines the direction of the current, and whether the polymer is stretching
or contracting. Resistance detection techniques can also be used to measure changes in the
resistance contained in the polymer or changes in the resistance of the electrode. Certain
examples of these techniques are described in commonly owned patent application 10 /
007,705, which was incorporated by reference above.
[0203]
6. Application example
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[0204]
Listed below are some exemplary applications for several transducers and devices that perform
the above-described thermodynamic work on fluids. The exemplary applications described herein
are not intended to limit the scope of the present invention. As those skilled in the art will
appreciate, the transducers of the present invention find use in a myriad of applications that
require conversion between electrical and mechanical energy.
[0205]
FIG. 7A is a block diagram of a human or animal-like host 500 connected to an EPAM device that
performs thermodynamic work on fluid. The EPAM devices of the present invention may be used
to provide a motive force to fluids in medical applications. Typically, EPAM devices move any
fluid, such as blood, air, medication with medicinal ingredients, lymph, food, spinal fluid, drainage
(eg urine), gastric juices, in the medical care of the host such as humans or animals. It can be
used for In particular, the EPAM device can be integrated into a medical device that performs
cardiac assistance such as pumping on blood instead of or with the heart. The EPAM device may
be used for medical devices that supply air to the human body, such as ventilators and lung assist
devices to help people who have difficulty breathing.
[0206]
In yet another embodiment, the EPAM device 1) moves the dialysis device (eg, transfers fluid into
and out of the body), 2) the plasma migration device (eg, moves plasma into and out of the body)
3) blood pump devices (eg, inject blood into the body as part of an infusion), and 4) drug delivery
devices (eg, inject drugs from IV or devices with drugs embedded in the body) Can be used to
perform thermodynamic work on the fluid as part of the delivery.
[0207]
An EPAM device that performs thermodynamic work may be external to the body (outside the
body) (501) and may be connected to the body in some way.
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For example, a dialyzer connected to the body or a device that circulates blood during heart
transplantation may use the EPAM device of the present invention. An EPAM device can be
located inside the body. For example, a medical device 502 that delivers an agent such as insulin
can be implanted subcutaneously and use an EPAM device to inject insulin into the body. In other
embodiments, the implanted device 502 can be an artificial heart or a heart assist device to aid a
damaged or diseased heart. In still other embodiments, EPAM devices that perform
thermodynamic work on fluids are wearable. For example, a person may wear a device 503, such
as an EPAM pump device that delivers medication.
[0208]
In other embodiments, EPAM devices that perform thermodynamic work may be used in clothes
or devices used in extreme environments. For example, an EPAM device can be used to move and
control fluid in a diving suit, circulate fluid in biological / chemical protective clothing, and
circulate fluid in fire protection clothing. The fluid that is circulated may be used for thermal
control, such as to control and cool the body temperature, or to provide a breathable fluid. The
fluid may be circulated in the space defined in the clothes or in the conduits resident in the
material used for the clothes.
[0209]
FIG. 7B is a block diagram of a car and a car subsystem 515 that employs an EPAM device to
perform thermodynamic work on fluid. EPAM devices, which perform largely thermodynamic
work, may be used to perform thermodynamic work on any fluid used within the automotive
subsystem. In particular, EPAM devices may be used within engine cooling subsystem 509 to
pump fluid, such as air or water, used to cool the engine in the internal conduit. The EPAM
devices may be used in cooling fans or devices used to move air from the outside around engine
components, such as engine blocks or radiators.
[0210]
In another embodiment, the EPAM device may be used in a windshield fluid system to deliver
windshield wiper fluid to the windshield. The EPAM device may be used in the fuel / air system
507 as part of a fuel pump that delivers fuel to the engine or as part of an air pump / compressor
system used in the engine. The EPAM device may be used within the heating / AC system 505 to
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deliver refrigerant as part of a cooling fan for a refrigeration system to deliver heated or cooled
air into the passenger compartment. The EPAM device may be used as part of an engine / oil
system 511 as an element in an oil pump. The EPAM device may be used as part of an exhaust /
contamination control system 506 for moving exhaust gases through the system.
[0211]
In certain embodiments, an EPAM device may be used as part of a tire system 510 for adding
compressed air to a tire. The tire pump can be located on each tire, which allows the tire to selfcontrol its own tire pressure. The EPAM tire pump can be connected to sensors that measure
pressure in the tire, road conditions (eg dry, wet, iced etc) and environmental conditions (eg
temperature). From the sensor data, the EPAM tire pump 510 may determine the appropriate tire
pressure and adjust the tire pressure when the vehicle is driven, when travel is started, and / or
while the vehicle is stopped. The tire pump may be connected to a sensor control system in a
motor vehicle.
[0212]
FIG. 7C is a block diagram of an EPAM device that fluidizes thermodynamic work within an inkjet
printer head 520. The inkjet printer head may include a plurality of capillary tube nozzles 523
which may be composed of EPAM material. An EPAM valve 524 may be used with each nozzle to
control the flow to the nozzles 523. The EPAM micro roll actuator 521 may be used to eject ink
from the ink reservoir 522 and pressurize the ink prior to ejection from the nozzle 523. Details
of EPAM valves and nozzles that may be used with the present invention may be found in copending US patent application Ser. No. 10/00, entitled "Electroactive Polymer Devices for
Controlling Fluid Flow," filed March 5, 2003 by Heim et al. No., which was described earlier here.
[0213]
In one embodiment, an integrated EPAM device may perform the functions of a pump, a valve
and a nozzle. A single EPAM element performs pressurization of the fluid (eg, ink) and then at the
end of the stroke of the pump portion of the EPAM device, or at a predetermined timed portion
the valve 524 (also pintle) of the jet nozzle 523 Can be called). The pressurized liquid can then be
atomized as it flows through the nozzle. This embodiment may be used when accurate metering
of the atomized jet is required, such as an inkjet head or a fuel injector of a motor vehicle.
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[0214]
6. Conclusion
[0215]
Although the present invention has been described for several preferred embodiments, there are
alternatives, combinations and equivalents which fall within the scope of the present invention
and which are omitted for the sake of brevity. For example, although the invention has been
described for some specific electrode materials, the invention is not limited to these materials
and in some cases air may be included as an electrode. In addition, although the invention has
been described for circularly wound geometric shapes, the invention is not limited to these
shapes, and wound devices with square, rectangular or elliptical cross sections and profiles Can
be included. Accordingly, it is intended that the scope of the present invention should be
determined with reference to the appended claims.
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