close

Вход

Забыли?

вход по аккаунту

?

код для вставки
Allg- 13, 1963
w. J. ToPAzlo ETAL
3,100,858
PRESSURE REBALANINGAAND MEASURING sERvosYsTEM
Filed Aug. 12, 1960
l
n
2 Sheets-Sheet 2
»ce
1
`
'
3,l00,858
Patented Aug. 13, 19.63
2
the need» for the earlier mentioned beam and, at the
same time, permits the E pick-off armature to be rotated
(about .an axis parallel to the torsion bar) so that it angu
3,100,858
PRESSURE REBALANCING AND MEASURlNG SERVOSYSTEM ’
>
' larly moves relative to the E pick-.ofi stationary member
William I. Topazio, Levittown, and John'D. Weir, Hunt
Filed Aug. 12, 1960, Ser. No. 49,365
when the-bellowsexpands or contracts. Elimination of
the beam is desired not only for weight and space saving
purposes, but because the beam is sensitive to vibrations
. 11 Claims. (Cl. .i18n-28)
and, as such, causes the-torsion bar to vibrate at its
ington, NX., assignors to Sperry Rand Corporation,
Great Neck, NSY., a corporation of Delaware
natural frequency when so excited. The beam configu
‘ This invention relates «generally to aircraft instruments 10 rations of this type >have low natural frequencies which
and more particularly to instruments which respond to
are easily excited. The beam, further, is highly sensitive
changes in pressure.
to accelerations (-both angular and linear) which re
A pressure responsive device of the type Vin which the
quires extreme balancing accuracy to correct. Angular
present invention may be employed is disclosed in U.S.
movement of the E pick-0E armature relative to the sta
Patent 2,729,780, issued in the name of I-I. Miller et al. 15 tionary member is preferred over armature movement
and `assigned to the assignee of the present invention.
which is parallel to the stationary member because a
In the structure disclosed in that patent,.a balancing beam
given E pick-off :output signal can be obtained, using the
which is rigidly connected to the center of a torsion bar
vangular movement arrangement, that is equivalent to the
twists the bar about its axis when a force -is applied to
parallel movement arrangement employing a multiplying
the beam. The force applied to the beam is derived 20 lever of 8 or 10 to 1.
from a bellows which responds to pressure changes. and
Generally, apparatus embodying the improved torsion
which is connected to the beam 4by a rigid link maintained
bar suspension system has the torsion bar rigidly secured
under tension. Generally, the link is maintained under
to the center of the _pick-on? armature and thereby rotates
tension by keeping the pressure on the outside of the
the larmature whenever the bar is twisted. The bellows
bellows 'always greater than the pressure Within the bel 25 is vconnected to one end of the armature by means of a
lows.
As the beam starts to move in response to the
V link of the type described earlier.
force applied from the bellows, it moves the armature
As the bellows ex
pands or contracts, it applies a torque about the axis of
the torsion bar k'by applying a force on one side of the
of an E pick-oli substantially parallel'to, but in spacial
alignment with, the stationary member of the pick-off.
armature. A link, which is likewise resilient to bending
This produces a pick-off output signal which operates a 30 forces but stiff to tensile forces, is connected between
motor that rotates the twisted torsion bar until the pick
~ the bar and the housing of the device Vand prevents the
oiï signal is cancelled. The amount the torsion bar is
bar from bending when the bellows exerts a 'force on the
armature.
rotated is proportional to the pressure change experienced
by the bellows.
"
'
Within the scope of this «feature of the invention, it is
Because ‘the balancing beam 'is rigidly connected to 35 recognized that the torsion bar need not «be rigidly se
the bellows and the torsion bar (which is restricted to rota
cured tothe center of the armature »as set forth above,
tional movement about its axis only), the bello-ws must ' but may be secured anywhere between the ends of the
bend whenever a pressure change causes it to expand or
armature. However, if the torsion bar does not connect
contract. Repeated bendin-g of the bellows adversely af
tothe armature center, the armature may respond to
fects its characteristics, thereby causing a decrease in the 40 vibrations and act like the balancing beam of the Miller
accuracy of the device. Furthermore, since pressure
A principal object :of the invention is to provide an
changes must lirst overcome the stiffness of the bellows to
improved pressure measuring device.
bending forces before the torsion bar may be twisted, the
device is insensitive to small pressure changes «which are
Another `object is to provide an improved coupling be
unable to bend the bello-ws. In practice, the torsion bar 45 tween a bellows and a device rotatable in response to
movement orf the bellows.
of this device is twisted only when a pressure change
equivalent to »an altitude change of at least 20` feet has
Another object is to provide an improved torsion bar
»_ A
been experienced.
>
patent.
suspension system ttor ruse in a pressure responsive device.
The 'invention will be described with reference to the
'
The present invention proposes, `among other things,
` the replacement Iof the aforementioned rigid link which> 50 ligures wherein:
FIG. 1 is a schematic diagram of apparatus embodying
connects the bellows to the torsion bar with a link which
the invention,
is stiffer to tensile forces, but much more resilient to
bending forces, than the bellows itself. With such a
link, the force of the -expanding or contracting bellows
may still be applied to twist the torsion bar but, because
the link is more ilexible to ben-ding forces than the bel
lows, only they link will bend as the bar is twisted. This
assures that the accuracy of the device will not deterior
ate, since the bellows can never become contorted. Fur
FIGS. 2a and 2b are diagrams useful in explaininga
`feature of the invention,
55 '
‘- IFIG. 3 is a perspective, partially cutaway View of a
presently preferred E pick-off armature tholder useable
'by apparatus embodying the invention,
FIG. 4 is a front view of the apparatus of FIG. 3, and
FIG. 5 is an end view of the apparatus of FIG. 3.
thermore,rthe` sensitivity of the device is determinedpri 60 Referring to FIG. l, a torsion bar 10 which is supported v
marily by the stilîness of the link to bending forces (and
in journal bearings 111 has the armature 1‘2 ofv an E pick
not by the stiffness of the bellows to bending forces) be- k
oif 14 :lixedly connected to it at 16. A pressure respon
cause this is the only stiffness which must be overcome
sive element, such as a bellows 18, is connected to one
in twisting the torsion bar. >vSince this stiffness can be
end of the armature 12 by means of a link 20, e.g. a wire,
decreased to substantially zero, the sensitivity of the de 65 which is stili to tensile forces, but resilient to bending
vice can be made very high. In practice, the torsion bar
forces. The link 20‘ is always maintained under tension
of a device employing a Wire or ilat‘spring link is twisted
by keeping the pressure within the bellows 18 less than
when a pressure change equivalent to an altitude change
the pressure on the outside of the bellows. In the event
of a mere six inches has been experienced.
~
the device is used as an absolute pressure measuring in
Aside from anf improved link «between the bellows and 70 strument, eg. an :altimeten the 'link 20 is maintained un
the torsion bar, the present invention provides an im
der tension by evacuating the bellows; this is the case
proved torsion fb-ar suspension system which eliminates
as set forth inFIG. l. When, however, the Idevice is
3,100,858
3
4
used as a pressure differential measuring device, eg. an
>istics of the different components with-in the device.
air speed measuring instrument, the bellows’ interior is
This will be explained in detail later.
exposed to` static pressure whereas the exterior of the
A positionable member '52 having a threaded hole is
connected to the base member 40 by means of a screw 56.
bellows is exposed to impact, or pitot, pressure. Main
taining the link 20' under tension is necessary to prevent
the link »from buckling, i.e. :assuming a bow-like form
when thebellows §18 expands. A link ‘22, preferably
'
~
The link 12d which connects` to the bellows 18 is then
connected to the positionable member S2. Thus, the
point at which force is applied to the armature support
variable. Variability -of the point of application of
similar to the link 20, is connected to the armature 12 at
force to the support is necessary to compensate, during
a pivot point 24 which lies in a plane which is orthogonal
to the axis of the torsion bar 10 and in which the link 10 calibration, for any mismatching between the character
istics of the bellows 18 and the torsion bar 10. 'Ilhe bel
20 is -free to bend. Itis preferred that the link 22` be
lows 18 likewise -is positionable so that, when the mem
similar to the link 20’ because, as the armature 12 is
ber 52 is repositioned, it too may be positioned and there
rotated by the force derived from the bellows 18, a bend
by keep any force developed by the bellows acting at a
ing lforce (which tends to bend thelink 22 in the afore- _
mentioned plane) will be applied to the link 22; if the 15
link 22
stiff to bending forces, the bellows will have
right angle to the base member 4th
Y
to overcome this stiffness in order to twist the torsion
a slot I64 in la dam-ping ñuid container 66. The support
'
A iiange 62 extends 'from the lbase «member 40' into
ing structure -for the container is not shown. The slot`
64 must be such that capillary action of the damping
as earlier described. See FIGS. 2a and 2b which show,
for ’instructive purposes, the effects of using stiff links in 20 iiuid, will prevent the fluid from ñowing out.v Within the
container 66, and extending from a side of the slot 64,
place of liexible links (the bellows here however having
is an Lashaped wall 68 which serves as an oil reservoir
internalV pressure so that it can push and pull the lower
and prevents Iall of the damping fluid from seeping out
link depending on ambient pressure). The output sig
through the slot when the device is turned upside down
nal, vif any, fromV the stationary member 26 of the pick
oif 14 is applied to an »amplifier Z8. The amplifier 28 25 or on its side `for an extended time period.' Whatever
bar-10, thereby decreasing the sensitivity of the device
then applies its output signal to a motor 30l which rotat- '
fluid is lost, however, may be replaced through a port
ably drives, through gearing 32, the torsion bar 10„and
(not shown) in the container y66.
'
`
When the pressure sensor elements experience `varying
the armature 112 to cancel the pick-od 14 output signal.
temperatures, the‘eifect is to rotate the base member '40
A tachometer generator 34 which is driven by the motor
30 reeds back, in accordance with established servo prac 30 about the axis of the torsion bar in proportion to these
temperature changes. This is caused by the dimensional
tice, a -rate ysignal to the amplifier 28 to damp the opera
»and modulus changes of the various parts. This rotation
tion of the motor'30. Shown being driven by the motor
is an altitude indicating instrument 36 and a potentiom
' of member 40“ as a function of temperature would produce,
eter 38 which may be used to provide the craft autopilot 35 therefore, an angular displacement between the pick-off
armature d2 and the stationary member 26, Iwhich would,
with a signal representing altitude. ySynchros or other
output devices :can be driven by the motor also.
When the apparatus of FIG. 1 is initially set up and
c-alibrated, the tension in the link20 is set so that the
armature y12 will be rotated (against the torsional force 40of the 'bar 10 which is :anchored at one end in gearing 32)
relative to the pick-olf stationary member 26 just enough
to produce al pick-off output signal which-will drive the
indicator 36 to read the altitude at which the device is
as earlier explained, cause the motor 30 to run (to cancel
that displacement) and drive the indicator '36 to a wrong
indication of pressure. ‘The bimetallic strip 46» displaces
the armature 12 (which is restricted to only rotation about
the torsion bar axis because it is secured to the movable
member 42) about that same axis in the direction to cor
rect for the temperature change. Thu-s, regardless of tem-
perature changes, the angular relationship between the
12 and the pick-off stationary member 26 is held
calibrated and rotate the bar 10 to cancel the pick-off 45 armature
constant.
`
output signal: With the device installed in an aircraft,
Adjustment slots are provided in the bimetal strip so
an increase in altitude will cause the bellows 18 to ex
pand, thereby reducing the tension in the link 20. This
causes the effect of the torsional force of the bar 10 on
that the displacement as a function of temperature can be
calibrated by changing the length of exposed bimetal
material.
“
-
the armature'12 to be greater than the eifect of the 50
While .the invention has been described in its preferred
tensile force of the link 20 and, asa result, the torsion
embodiments, it is to be »understod that the words which
bar will untwist to balance the two force effects. 'Ir'his
have been used are words of description rather than of
causes the armature 12 to assume an angular relationship
limitation and that changes within the purview of lthe
with the pick-olf stationary member 26, thereby produc
appended claims may be made without departing from the
ing a pick-off 14 output signal (as earlier described) 55 true scope and spirit of the invention in its broader as
pects.
which operatesy to rotate'the torsion bar to cancel the
signal and, at the same time, drive the indicator 36 to
Vread the higher altitude. A decrease in altitudev will in
crease the tension in the link 20, the effects of which were
described in reference to the setting up and calibration
of the device. ~
Referring to FIGS. l3, 4 and 5, the presently preferred
What is claimed is:
1. A pressure responsive device comprising a bar ro
tatable about its own longitudinal axis, means movable in
response to pressure variations, tensilely stiff and bendably
resilient connecting mean-s Íixedly connected to said rotat
able bar and to said movable means to rotate said ro
tatable bar in proportion to said pressure variations, and
armature support is provided with a base member 40
which is «ñxedly connected to the torsion bar ‘10‘, The 65 means for maintaining said connecting means under ten
sion.
support -is further provided with a movable member 42
2.. A pressure responsive device comprising meansro
which is rotatably mounted in bearings 44 on the bar 10.
tatable about an axis, means positionable in response to
A bimetallic strip 46 is rigidly connected to a »leg 48
changes in pressure, means under tension iixedly connected
extending front the base member 40 and to the E pick
to said positionable and rotatable means to rotate said ro
oif armature 12. The armature 12 in turn is rigidly con 70 tatable means in proportion to pressure changes,v said
nected to the movable member 42. Fixedly supported
means under tension being stiff to tensile forces and flex
ible to bending Iforces, means responsive to produce a sig
above the :armature by means of a bracket `50 is the sta
tionary member`26 of the pick-oit. Cooperation among
nal proportional -to the amount said rotatable means ro
tates, and means receiving said signal operable to rotate
the elements `40, 42, 44, 46 and 48‘ provides compensa
tion for temperature variations which vary the character 75 said_rotatable means an amount substantially equal to,
5
3,100,858
6
.
but opposite, the rotation produced by said tension means.
3. A pressure transducer comprising a »torsion bar,
positionable means and applying a torque about the lon
means movable in `response to pressure changes, means
stiff tot Iforces along its longitudinal axis and resilient to
bending forces, and means responsive to the torsion of
Vsaid _bar to apply a» torque to said torsion bar .to cancel
gitudinal axis of said bar, said means under tension being
maintained under ten-si-on connecting said movable means
to said ltorsion bar and applying a torque about »the longi- `
tudinal axis of said bar, said means under tension being stii‘r"
to forces lalong its longitudinal axis and resilient to bending
forces, and ‘means responsive to the torsion of said bar to
substantially the torque applied by said movable means.
10. Apparatus responsive to variations in pressure
comprising a torsion bar, a barometric device movable
apply a torque to said torsion bar to cancel substantially
in_ response to» pressure changes, support means connected
the torque applied by'said movable means.
10 Vto said torsion bar, means rotatable about the longitu
4. A pressure responsive device comprising movable
dinal axis of said` torsion bar, pick-oilE means having a
Vmeans, a Ibarometric device responsive to pressure varia
stationary and movable member producing a. signal pro
tions -to move said movable means, a torsion bar, means
portional to the angular misalignment between its mem
under tension connecting said movable means 4to said tor
bers, said movable member being connected to said sup
sion bar and applying a torque about said torsion bar
port means and said means rotatable about the longitu
longitudinal axis, -said means -being ilexible to forces per
-dinal axis of said torsion bar, means responsive to tem
pendicular to its longiutdinal axisV and stiff to forces along
perature changes to rotate said rotatable means relative
its longitudinal axis, and means responsive when a torque
to said support means, means maintained under tension
is applied to said bar by said tension means to cancel
connecting said barometric ‘device to said support means
substantially that torque by twisting said bar.
L20 applying a torque about'the longitudinal axis of said
5. Pressure responsive apparatus comprising a bellows,
torsion bar to rotate said pick-oit means movable mem
ber, said rotatable means, and said support means about
said torsion bar longitudinal axis when said barometric
tudinal axis of said bar, said means under tensio-n being
device moves, said means under tension bein-g stiff to 1on
stiff to tensile forces and substantially more flexible to 25 ~gitu-dinal forces and resilient to bending tforces, and means
a torsion bar, means undervtension connecting said torsion
bar to said bellows and applying la torque about the longi
bending forces than said bellowaand means responsive
responsive tosaid pick-off means signal yoperable with
when a tor-que is applied to said bar Vby said means under`
tension to cancel substantially that torque by twisting said
bar.
said torsion bar to apply a torque to the bar and thereby
cancel substantially any angular misalignment between
the pick~oiî means members.
-
6. Pressure responsive apparatus comprising a torsion 30
1l. Apparatus responsive to variations in pressure com
bar, pick-off means having ya stationary and a movable
prising a torsion bar, a barometric device movable in
member, said movable member being connected to said
response to pressure changes, support means connected
torsion bar, means movable in response to pressure’varia
tions, means maintained under tension connecting said
' to said torsion bar, positionable meansl connected t-o said
support means, means rotatable about the longitudinal
pick-olf means movable member to said means movable 35 axis of said torsion bar, pick-ott means having a station
in response to pressure variations applying a torque about
ary and movable member producing a signal proportional '
the longitudinal axis of said torsion bar, said means main
' tained under «tension being stiiî to longitudinal forces and
to the angular misalignment between its members, said
movable member being connected to said supportmeans
resilientïto forces tending to bend it, said stationary mem
and said means rotatable about the longitudinal axis of
ber producing a signal when said movable member moves 40 said torsion bar, means responsive [to temperature changes
relative to it, and -means receiving'said signal operating
to notate said rotatable means relative to said support
to twist said >torsion bar in proportion to said signal and
means, means maintained under tension connecting said
thereby maintain the relative positions of said stationary
barometric device to said positionable means applying a
and movable members substantially constant. i
torque about the longitudinal axis of said «torsion bar to
7. The structure of lclaim 6 wherein said means main 45 rotate said picksolf means movable member, said ro
tained under tension is a wire.
,
tatable means, and said support means about said torsion
:8. Pressure responsive «apparatus comprising a torsion
bar longitudinal axis when said barometric device moves,
bar, pick-off means having a'stationary and a movable
said means under tension being stiff to longitudinal forces
member, said movable member being connected to said
andv resilient to bending forces, means responsive Yto
to-rsion bar, means movable in response to pressure varia 50 said pick-off means signal operable with said torsion bar
tion-s, means maintained under tension connecting said
to apply a torque to the barl and thereby substantially
pick-oft” means movable member to- said means movable
cancel
any angular misalignment between the pick-olf
in response to pressure variations applyi-ng Ia torque about
>means members, containing means having an opening
the longitudinal axis of said torsionfbar, said means
means extending partway into said containing
maintained under `tension lbeing stili to longitudinal forces 55 therein,
means from one side of said opening and forming an
and resilient to forces tending to `bend it, said stationary
inverted cup with the sides »off said containing means,
member producin-g a signal when said movable member
ríluid in said containing means, and means connected to
moves relative to it, means receiving said signal operat
said support means extending into said containing means
ing to twist said torsion bar in proportion to said signal
and thereby main-tain the relative positions of said sta 60
tionary and movable members lsubstantially constant, con
taining means having an opening therein, means extending
partway into said containing means Ifrom one side of
through said opening. `
»
References Cited in the ñle of this patent
UNITED STATESPATENTS
said opening, and forming an inverted cup with the sides ~
'of said containing means, fluid in said containing means, 65
2,115,086
and means connected to said movable member and ex-- '
2,720,620
Power _______ __'..... __ Oct.„1l, 1955
tending into `said containing means through said opening.
tionable means connected to said torsion bar, means mov
2,729,780
2,788,665
2,798,191
Miller etal. ___________ __ Ian. 3, 1956
Wainko ______________ __ Apr. 16, 1957
Brailsfond ____________ __ July 2, 1957
able in response to pressure changes, means maintained 70
under tension connecting said movable means to said
2,849,669
2,980,835
Kinkel ___________ ___-- Aug. 26, 1958
Williams ____________ __ Apr. 18, 1961
9. A pressure transducer comprising a torsion lbxar, fp-osi->
Riggs ___-; __________ _.- Apr. 26,*1938
Документ
Категория
Без категории
Просмотров
0
Размер файла
747 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа