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Патент USA US3094874

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June 25, 1963
Filed Oct. 12, 1960
Patented June 25, 1963
?atten or de?ect from a slightly cupped or saucer-like
cross-section when impressed by movement of the central
mass. Since they are pre-formed to the cupped shape,
they tend to restore their original cupped shape when
the imposed load is relieved. This ‘a?ects the frequency
Roy G. Kahkonen and Robert A. Bartlett, Fort Walton,
FliL, assignors to the United States of America as repre
response of the unit to help diminish mechanical hysteresis.
sented by the Secretary of the Air Force
The term “negator” has been applied to the precoiled
Filed Oct. 12, 1960, Ser- No. 62,313
spring that rewinds itself after an imposed load is re
2 Claims. (Cl. 73-712)
A preload adjusting device is provided to control the
This invention relates to a capacitive type omni-direc 10
spacing between the encapsulated capacitive elements and
tional transducer which comprises a cubic structure hous
ing six capacitor elements, two opposed capacitors posi
the central mass.
Unwanted play or looseness can thus
be adjusted out, and a minimum preload setting obtained.
When forces of high magnitude are being measured, it is
the principle of capacitive changes which occur in these
to make a tighter ‘adjustment. The initial mini
elements when acted upon by a centrally located spherical 15 necessary
mum capacitance values can be raised above the nonlinear
mass of selected density, the spherical mass reacting to
slope encountered in low load conditions by tighter ad
external forces. The device is capable of response to
justment and regulated compression of the encapsulated
forces from any plane or planes, converting these forces
elements. For example, the volume of 180‘ 1111f. at 120
into corresponding capacitive changes.
per square centimeter has been approximated.
In the drawing, the FIGURE represents a perspective 20 grams
The preload adjustment comprises a ?nely threaded
view of the transducer showing one side of the device and
tioned on each of three axes.
The device operates on
screw element 26 which engages a complementarily
one of the capacitive units in exploded condition.
threaded opening 28, one being provided in each side 12
The six capacitors are contained in a cubical structure
of the cube body 10. Six preload adjustments are pro
or transducer body indicated in the drawing at 10. The
two for each axis. They are used to preadjust the
cubical transducer body structure It} is comprised of six 25 vided,
elements for the reasons above noted, and to
plane sides 12 and may be supported by any expedient
center the mass in the physical center of the transducer
The means shown is a mounting frame 15 sur
rounding the periphery of one of the sides of the struc
body 10.
As will now be apparent, when the transducer is sub
30 jected to a vibrational or acceleration force, the dense
In each of the three major axes of the cubical body 10
‘central mass 14 tends to move either backward or for
there are two sets of capacitive elements separated by a
ward, up or down, right or left. The movement com
heavy metal mass 14 of selected density and may be a
ture 10.
presses one set of capacitive elements, thus increasing its
while it decreases pressure on the opposite set
Each capacitor comprises the following elements: a plu 35 capacity,
of capacitive elements and decreases their capacitance.
rality (seven as shown) of capacitor elements 16 are de
The transducer is adaptable for a variety of uses and
formable resilient metal plates capable of ?exing and re
the special use governs the type and detail of the circuitry
turning to original shape. They may be convexed or
to be used with it.
shallow saucer shaped elements of any suitable metal. A
The following examples are given to illustrate uses of
good grade of brass, ‘silicon bronze, steel shim stock or 40 the transducer and it will be understood that the inven
gold plated steel are examples of materials found suitable
tion is not limited to these uses:
for this purpose. The capacitor plates 16 are provided
(1) As a weapon ?ring rate indicator and rounds coun
with contact or lead elements 18 which connect into a
ter, a standard capacitive bridge circuit would be used
standard circuit (not shown) whose character is deter
which would also be connected to an integration circuit
mined by the particular purpose for which the transducer
45 and electronic counting device calibrated to give an indi
is to be used.
cated output in pulses per minute.
The capacitor plates 16 are sandwiched with ?exible
(2) To accomplish the basic function of measuring vi
dielectric separators 20. These insulator disks may range,
a standard peak reading A.C. voltmeter would
for example, from 0.0001 to .005” depending on the capac
conjunction with the capacitive 1bridge.
itive range and sensitivity desired. They are made of
'(3) Acceleration is measured the same way, using a
mica, plastic, glass or other insulating material found 50 DC.
voltmeter or any type of graphic recorder. The
out-put of the device, when used in conjunction with a
The unit comprising the capacitor plates 16 and the
capacitive bridge, will be a sine wave function whose
sandwiched mica separators 20 are encapsulated, except
amplitude is directly related to the amplitude of vibra
for the protruding terminals 18 in a polystyrene or simi
tion. The frequency of the sine wave will be equal to
lar plastic ?lm. The units to be encapsulated are des
the frequency of the vibration or to a harmonic.
ignated in the drawing by the letter C. The unit thus
(4) When using the device to determine the vectorial
assembled will respond to pressure by “?attening out,” as
‘axis of a vibration plane, the three dual capacitive ele‘
space under each deformed plate is diminished.
ments must ?rst be equally calibrated as to output. The
For each capacitor unit inner and outer spring negator
resultant direction is then determined by integration of
plates are provided, as shown at 22 and 24 respectively. 60
all three outputs with respect to a ?xed reference axis.
The inner spring plate 22 receives the impulse from the
While the invention is shown and described in connec
mass 14 and transmits it to the encapsulated capacitor
with one form for illustrative, rather than restrictive
unit C. The outer plate 24 is interposed between the
purposes, it is obvious that changes and modi?cations may
capacitor unit C and an inner adjacent surface of 1a side
be made by those skilled in the art without departing
12 of the ‘body 10‘. The negator plates do not enter into 65
from the scope and spirit of the invention as de?ned in
the electrical characteristics of the device since the wanted
the accompanying claims.
measurements are taken from instruments (not shown)
We claim:
connected to the terminals 18. They are, however, im
1. An omni-directional transducer system capable of
portant in the system because they act to diminish me
chanical hysteresis which has an electrical analogue value. 70 receiving and transmitting for measurement vibrational
and G-load forces from any direction, said system com
The “negator plates” are deformed metallic springs that
cube or a sphere, as desired.
‘prising a cubical hollow body, six sides on said body, a
movable mass of known density located in said body, six
capacitor units, each unit comprising a plurality of ?ex
G-load stresses, said system comprising a hollow cubical
container comprised of six walls each wall provided with
ible deformable capacitor plates and a plurality of di
known density positioned therein free from attachment
electric elements placed in sandwiched formation, two
capacitor units being located on each axis in said cube,
one on each opposite side of said central mass, six pairs
of negator spring elements, one negator of each pair lo
cated inwardly and one outwardly with respect to each of
an opening therethrough, a spherical central mass of
and rotatable therein, pairs of capacitor units located in
balanced relationship around said central mass and posi
tioned between said central mass land a wall of said cubical
container, means for varying and adjusting the capaci
tance of each of said capacitor units from the exterior of
said capacitor units, a negator element being interposed 10 said container, said means comprising adjusting members
between each capacitor unit and an interior side of said
located and adjustable in said openings in said walls, the
cube, and a negator element being interposed between
of each capacitor being subject to measurable
each capacitor unit and said central mass, said central
change responsive to increased or decreased pressure
mass moving in response to vibrational and G-load
from within said container by movement
changes to vary the distance between said capacitor plates 15‘ placed'thereon
of said central mass.
and thereby vary the capacitance of each capacitor unit,
terminals on said capacitor plates for connecting selected
References (Iited in the ?le of this patent
electrical measuring instruments for making desired ob
servations, a preloading adjusting means located in each
side of said cubical transducer body for removing loose
Marvin ____________ __ May 29, 1934
ness and play in the elements of said transducer, for 10
Blau et a1. __________ __ ‘Dec. 31, 1935
eating said mass in ‘balanced relationship to each capaci
Ellsworth ____________ __ Jan. 25, 1944
tor unit and, when desired, for applying pressure to said
Roberts ____________ _._ Dec. 4, 1945
capacitor plates for raising the capacitance values of said
Buisson ____________ __ June 23, 1959
capacitor elements above the nonlinear slope.
2. An omni-directional transducer system for receiving
and transmitting for measurement vibrational forces and
Canada ______________ __ June 14, 19601
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