US2411747A - Control device - Google Patents

Description

Nov. 26, 1946. c. A. NEL'soN CONTROL DEVICE Filed Aug. 31, 1944 INVENTOR l 'ClaudeANelsm BY Qfz ATTORNEY Prasad Nome,

Claude A. Nelson, Wilmerdin'Pa.,

The Westinghouse Air Brake Company,

assigner to Wil- merding, Pa., a corporation of Pennsylvania Application August 31, 1944, Serial No. 552,024

z claims. (01121-41) This invention relates to control devices and ,more particularly to fluid pressure controlled and v operated motors.

One object of the invention is the provision of an improved motor of the above type.

Fluid motors employed on airplanes for ad-v justing various devices such as engine throttles, mixture control devices etc. must be as small, compact and light in weight as possible, and another object of the invention is the provision of an improved fluid motor embodying these characteristics and therefore particularly adapted, though not limited, for such use.

4 opposite the strut head l. At the opposite or right hand side of diaphragm 5, as viewed in the drawing, is a chamber I3 which is open to atmosphere through a port I4 and winch contains a The fluid motor embodying the invention com V prises a power member which.A may be in the form of a piston and which is adapted to be oper-` ated by fluid under pressure to effect .adjustment of the device to which it may be operatively connected, and a pilot portion arranged for control by fluid under pressure to control the pressure of fluid on the powe'rpiston, and according to another feature of the invention a single pipe is employed for controlling the pilot portion of the motor and for supplying fluid under pressure to the motor for actuating the power piston, thereby maintaining at a minimum the weight of the system for controlling the motor.

Other objects and advantages will be apparent from the following more detailed description of the invention.

In the accompanying drawing, the single figure follower I5 engaging the adjacentface of said diaphragm. The strut heads 8 and 8 and oppositely arranged followers AI2 and I5 are secured to the respective diaphragms by any suitable means or in any suitable manner, not shown in the drawing.

A bore is provided centrally through the strut head 8, follower I2 and the interposed portion of diaphragm 4, and slidably mounted in this bore is a fluted stem I8. A fluid pressure supply valve Il disposed in chamber I8 is provided on one end of the stem I6, while on the opposite end of said stem, which terminates I'in chamber 8, there is provided a fluid pressure release valve I8. The follower I2 has a seat for engagement by the supply valve I1, while a seat for the release valve I8 is provided on an arm I9, the seat extending around one end of a bore 20 in said arm. 'I'he arm I8 is an integral part of the casing section 2 and extends into the space between the two strut heads 8 and 8. The opposite end of bore 20 opens to a chamber 2| in arm I8 and said chamber is connected by a passage 22 to 9;/ fluid release pipe 23. f

The fluid release pipe 23 may lead-directly izo 50 atmosphere, or it may be 'connected to' a sump is a longitudinal sectional view of a fluid motor embodying the invention.

Description The improved fluid motor comprises a casing l made up of sections' I, 2, and 3 which are adapted to be rigidly secured together inthe relationship 4 in which they are sho'wn i'n the drawing.` A flexible diaphragm 4 is clamped around its edge between the casing sections I and 2, while a flexible diaphragm 5 is clamped around its edge between the casing sections 2 land 3, said diaphragms being of the same areas and arranged l 45 time. In the present application it is merely dea combined, or common control and fluid pressure supply pipe I I. Chamber I0 contains a follower` I2 engaging the adjacent face of diaphragm reservoir (not shown) employed for receiving fluid under pressure after it has been used to produce a desired operation. Fluid'under presv sure thus released to the sump reservoir will then 5 be recompressed into a storage reservoir for use again. Particularly on large airplanes where many fluid motors will be used for controlling different devices, pressure of fluid in the sump reservoir may vary from. for instance, atmos- 40 pheric pressure when no fluid pressureis being released to the reservoir, to, momentarily, arelatively high degree, such as thirty-five pounds, if fluid under pressure is released to said reservoir from al1 of the controlling motors at the same sential in the present application, although if desired, reference may be made to the copending application of Rankin J. Bush, Serial No. 480,161,

of said bore is a, hollow cap 24. Slidably mount- Y ed in this bore is a sleeve 25 extending into control chamber I and having a closed end which engages the supply valve I1. A coil springv 2B -mounted .in sleeve 25 and having one end bearing againstl the closed end of said sleeve, extends into cap .24. The opposite end of spring 26 bears against cap 24. 'Ihis spring is under pressure and acts on the supply valve I1 with only sufflcient force to ensure seating of said valve against the follower plate I2 or seating of the release casing section I when said ycasing section is removed from the section 2, so as to hold the spring 26 and sleeve 25 assembled within the casing section I, under such a condition.

-The casing section 3 has a bore 28-formed in coaxial relation with the diaphragms 4 and 5 and containing a power movable abutment which may be in the form of a piston 29. The chamber I3 is provided at one side'of piston 29 whereby said piston is constantly subject on this one side to atmospheric pressure. At the opposite side of piston 29 is a power or operating pressure chamber 30 which is in constant communication through passage 3I with chamber 6 formed between the two diaphragms 4 and 5. Y

The piston 29 has a stem 32 extending through chamber 30 and a bore in the casing section 3 to the exterior thereof. A resilient ring 33 carried in an annular groove in casing section 3 has sealing and sliding contact with the portion of the piston stem within the bore in said casing section to prevent leakage of uid under pressure from chamber 3l) around said stem to atmosphere. Y

The outer end of the piston stem 32 is connected by a pin 34 to a lever 35 at a point between the ends of said lever. One end of lever 35 is connected by a pin 36 to a fulcrum link 31 mounted t6 turnon a pin 31a carried in the casing section 3. In the opposite end of lever 35 is a hole 39 for receiving a pin (not shownyto connect said lever, and thereby the power piston 29, to a device which it is desired to operate.

In chamber I3 are two concentrically arranged coil springs 39 and 40 both of which bear at one end against the piston 29. The opposite end of spring 39 is supported on a shelf 4I projecting from casing section 3 into chamber I3. The opposite end of spring 49, which may be called a regulating spring, bears against the diaphragm As above mentioned, pipe I I constitutes a combined control and nuid pressure supply pipe, that is to say constitutes a control pipe for controlling operation of the `diaphragms 4 and 5 and thereby` 4 pipe will preferablybe in excess of atmospheric pressure, for example it may be iifty pounds.

The spring 40 is interposed between the dia phragm follower YI5 and power piston 29 under such adegree of pressure that, with the `piston 29 in a. normal position dened by contact with a stop 42 in casing section 3, the pressure of said spring on the diaphragm follower I5 will hold the diaphragms 4 and 5 against the opposing control pipe pressure (50 pounds) in chamber I0 in a position in which the supply valve I1 will be seated and the release valve I8 will also be seated or slightly open.

The spring 40 is connected to the powerpiston 29 to renderl said piston effective to control,

through said spring, certain operation of the diaphragms 4 and 5 and valves'll and I8, as will be l"later described, but it will be noted that said spring is .also effective to urge piston 29 in the direction of stop 42. The spring 39,15 confined under pressure between the shelf 4I and piston 29 and its sole function is to urge the piston 29 into contact with stop 42 upon reducing pressure of iiuid in chamber 30, as will be later described.

It will be understood that the spring 39 is required to coact with spring 40 to move piston 29 in the direction of and into contact with stop 42 only in case the resistance to such movement exceeds the pressure of spring 43, as may bethe case where piston 29 is of relatively large area,

l or where a Arelatively great force is required t0 operate lever 35 and the device which may be connected to said lever. movement of piston 29 in the direction of stop 42 were suiiiciently great, the pressure of spring 40 on said piston might be of negligible value in obtaining such movement. However, if the force opposing movement pf piston 29 in the direction of and into contact with stop 42 does not exceed the forceof spring 40, then the spring 39 might be dispensed with.

Thearea of' piston 29 'is such as to render it effective to rock lever 35 to operate the connected device (not shown) against the opposing pressure of spring,40 or of both springs 39 and 40 by a lower pressure vof iiuid in chamber 30 Y than is required inchamber I0 on diaphragm 4 to move said diaphragm. the str ut 1 and dia-v Let it' initially be assumed that the control pipe II and control chamber I0 arecharged with fluid at the minimum pressure of fifty pounds above mentioned. Under this condition, the parts of the motor will assume the positions in which they are shown in the drawing, as will be apparent from the foregoing description.

If the pressure of iiid in pipe II and in chamber III is now increased, this increased pressurev effective on diaphram 4 will overcome the opposing force of control spring 40 and move the diaphragms 4, 5 and strut '1, and followers I2 and I5 and the adjacent end of said spring in unison against the opposing force of said spring and relative to the opposite end of said spring `rand piston 29. If the release valve I8 is not seated when the pressure in chamber I 0 is at thenormal de'- gree, the initial deflection of the diaphragms will permit seating of said valve under the action of spring 25. With the release valve I8 seated, however, said valve will hold the supply valve I1 If the force opposingagainst movement with the diaphragms, so

chamber vI 9. as be evident from the above description.

'In the operation lust described, the piston 29,

due to thefaction of spring 49, may or may not move in unison with the'diaphragms 4, 9 as they? .i

are operated to openthe supplyy valve I1, depend- `When the pressure of fluid supplied to chamber 39, and acting on piston 29 is then increased to a degree sufficient-to overcomespring 49 or of, both springs 99 and 49, as the case may be, and to also actuate lever 35 to operate the device being controlled, said piston will move against the opposing force of said spring or springs, and such movement will act to increase the force of spring 49 opposing the pressure of fluid in chamber I9 on diaphragm 4.

Now assuming that the increase in pressure of fluid in chamber I9, eective on diaphragm 4, is limited to some degree lower than maximum pressure, then when the pressure of spring 49 is increased, by movement oi? piston 29, to'a degree sufllcient to overcome the opposing force of said pressure of uid 'in chamber I9, said spring will be operated by said piston to move the diaphragms and followers in the direction of the open supply valve I'l and finally move the follower I2 into seating engagement with said valve. When the supply valve is thus closed, further flow of fluid under pressure will be prevented to chamber 99 and, as a result, movement of the piston 29 will cease. When the piston 29 stops moving, the spring 49 becomes static and movement of the diaphragms will also cease ina position in which the release valve will be still seated, whereby the fluid under pressure will be bottled in chamber 39 to maintain the piston 29 andlever 35 against movement.

From the above description it will be noted that the power piston 29 moves to a position determined by and corresponding to the degree of increase in pressure of fluid in chamber I9 above the normal orminimum pressure, and it; will be 'ton 29 doesnot move with the diaphragms 4, 5 A

ing upon the resistance to movement of the device (not shown) which is operated by lever Il. If this resistance is sufilciently great the piston 29 may remain stationary when the diaphragms 4, 9 operate to open the supply valve Il, but if sufllciently small, said 'piston may move with said diaphragm to open the supply valve. If the pisto open the supply valve I1, it will-be immaterial however, since as little. as one one-thousandth Y of an inch movement will open said valve to sup-v ply fluid under-*pressure to chamber 39'tostop A such movement of said piston. Moreover, this further noted that this movement of the power piston, while opposed by springs 39 and 49, is dependent upon a sumcient increase in pressure in chamber 39 to actuate the lever 35 and the device which may be connected to said lever. Thus a relatively low pressure of fluid in chamber 39 may be adequate to operate the piston 29 at one time or under a certain condition, while a higher pressure of fluid will be required to cause the same movement of said piston at another time or under a different condition. The area of piston 29 is such however that under all conditions it will be moved against spring 49, by fluid in chamber 39 at a, lower pressure than is present in chamber I9, and in pipe i I which constitutes the source of supply of fluid under pressure for operating said piston.

Now let it be assumed that the pressure of fluid l small amount of movement of piston 29 would. have substantially no eiect upon the device con-. nected to lever 3S, and said piston will be promptly operated by the uid under pressure supplied to chamber 39 to the position corresponding to the increase in pressure in chamber. I9, as above described.

It will now be seen that the piston 29 can bev caused to- ,move from the normal position, in which it is shown in the drawing, to any selected position at the left hand side of normal position vvby providing the proper pressure of fluid in cham ber I9 in excess of the normal or minimum pressure. 1 v

'With the piston 29 moved awayfrom stop 42, due to the pressure or fluid lin chamber I9 having been increased as above described, let it be assumed that it is desired to move said piston back in the direction of said stop. To accomplish this, the pressure of iluid in chamber I9 will be reduced to destroy the equilibrium between its effect on diaphragm 4 and the opposing pressure of spring 49. Spring 49 will then deflect the diaphragms in the direction of chamber I9. This movement of the diaphragms and thereby of the seatedV supply valve I'I will act through the stem I6 to pull the release valve I8 out of contact with its seat,

f whereupon fluid underpressure will be released movement will allow expansion of spring 49 and thus a reduction in the force it exerts againstJ the diaphragms.

Assuming that the pressure of fluid in chamber I9 is not reduced to its normal degree, then as soon as the pressure of spring 49 becomes reduced, as just described, to a degree which subon the diaphragm 4. -When the release valve is thus closed further release of fluid under pressure the degree of reduction in pressure of fluid in chamber iii, or in other words, corresponding to the pressure in said chamber in excess of the'normal minimum pressure.

In the operation just described, the piston 29 may, or may not, move in unison with diaphragms 4 and 5 in response to a reduction in pressure of iiuid in chamber i0, depending upon the resistance to movement of the device (not shown) connected to lever 3 5, as will be obvious from the,A above description of operation of the device in response to an increase in pressure of uid in chamber i0. Regardless of this, however, the piston 29 will be moved to a position correspondlng to the pressure of iluid in chamber I0 upon a reduction in such pressure, as above described.

Upon a further reduction in pressure of iiuid in chamber I0, the motor will again operate, as just described, to cause a corresponding change in position of piston 29. If the pressure of uid -in chamber I0 is reduced to the normal degree, the

e piston 29 will be moved by spring 39 or springs 39 and d0 to its normal position in which it is shown in the drawing. Before the release valve I8 seats or it may seat at the instant said piston engages stop 42. In either case, a complete return of the piston 29 to its normal position will be obtained.

If as just mentioned the release valve I8 is seated at the time piston 29 contacts stop 42, the pilot diaphragm 4 will be conditioned to operate to more quickly open the supply valve I1 upon a subsequent increase in pressure in chamber l0, also, the closing of said valve at this time may bottle up fluid ir said chamber at a pressure insuiiicient however to move piston 29 out of contact with said stop. This bottled pressure however will render piston 29 more quickly responsive to a subsequent supply o1' iluid under pressure to said chamber by opening. of thesupply valve I1, as will be readily apparent.

It will now be seen' that the power piston 29 can be caused to move toward and to be stopped,

in any selected position out of its normal pesi-Y tion by reducing the pressure fluid in chamber IUI to the proper selected degree, or the fullvand uninterrupted return to normal position may'be ob'- tained, if desired, by a continuous reduction in pressure of fluid inchamber Il) to'the normal minimum pressure. f

It will be noted that the pressure of uid in chamber 39 also acts in chamber `6 at all times but has substantially no influence upon the'above described operation of the pilot portion of themotor due to its action on one diaphragm being counteracted by its effect on the other diaphragm.

In case pipe 23 is connected to a sump reservoir, as hereinbefore mentioned, it will be seen that the pressure cf'ffiuid in chamber 30 can only be reduced as above described, to the pressure effective in said reservoir. The pressure of springs 39 and 49 is such however as to insure movement of the piston 29 into contact with Istop 42 against the maximum pressure which may be eiective in the sump reservoir and in chamber 39.

It will now be apparent that I have provided a power motor which is relatively simple and compact and which may be relatively small and light in weight, for the purpose intended. The motor comprises a power portion which is operable by uld under pressure, and a iluid pressure controlled pilot portion for controlling the power portion, and a single or common pipe serves asl a control pipe for the pilot portion and as a fluid pressure supply pipe, or as a source 'of fiiiid under pressure, for controlling operation of the power portion. v

Having now described my invention, what I claim as and desire to secureby letters Patent, is:

1. A 'lluid motor comprising a casing, power means in said casing subject on. one side to pres sure of fluid in a power chamber, pilot means in saidcasing arranged in coaxial relation to said power means and subject on the opposite side to pressure of fluid in a control chamber connected to a iluid pressure supply and control passage. a coil spring in said casing acting on adjacent sides ofsaid power andpilot means in opposition to pressure of iluid in the respective said chambers, valve means controlled by said pilot means for controlling communication between said passage and a third chamber at the opposite side of said pilot means,means opening said third chamber to said power chamber. said valve means also controlling a communication between said third chamber, and thereby said power chamber, and atmosphere, said pilot means being operable upon an increase in pressure of uid in said control chamber to effect operation of said isaid casing arranged in coaxial relation to said 'power means and subject on the opposite side to pressure of fluid in a control chamber, a coil spring in said casing acting against adjacent sides of said power and pilot means in opposition to pressure of fluid in therespective said chambers, valve means in said casing controlled by said power and pilot means and operable by said pilot means upon an increase in pressure of fluid in said control chamber to supply iluid to a third chamber at the opposite side of said pilot means and operable upon a'reduction in pressure of uid in said control chamber to release uid under pressure from said third chamber, means providing a constantly open communication between said third chamber and said power chamber, said power means being operable either against or by said spring means, to a position corresponding to the increase or reduction in pressure of fluid in said control chamber, to. effect operation of said valve means to bottlethe iiuid pressure in said third and power chambers, the pressure of fluid in said third chamber being effective on said pilot means in opposition to pressure of fluid in said-control chamber, and means operable by pressure of 'iluid in said third chamber to counteract the effect of the pressure of fluid in said third chamber on said pilot means and also rendering the adjacent side oi.' said o power means subject to atmospheric pressure.

CLAUDE A. NELSON.

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