US3227181A

US3227181A - Fluid pressure operated valve for hydraulic device

Info

Publication number: US3227181A
Authority: US
Inventors: James R Parr
Original assignee: New York Air Brake LLC
Current assignee: New York Air Brake LLC
Priority date: 1962-08-10
Filing date: 1965-01-26
Publication date: 1966-01-04
Anticipated expiration: 1983-01-04

Description

J R. PARR Jan. 4, 1966 FLUID `PRESSURE OPERATED VALVE FOR HYDRAULIC DEVICE Original Filed Aug. 10, 1962 ATTORNEYS vm mm om mm `Various hydraulically actuated devices. ,starting torque characteristics of the main engines are Vsuch that their starters must be operated at a higher pressure than eitherthe auxiliary engine starter or the :hydraulically actuated .devices in order to keep their size ,Qriginal application Aug.` 10,1962, Ser. No. 216,191.`

Divided and `this application Jan. 26, 1965, Ser. No. `435,772

' 1 Claim. (Cl. IS7-625.66)

This application isa divisionof ,application Serial No. 216,191, filed August 10,` 1962.

This invention relates fto hydraulic pumps, and more Lparticularly, to `discharge pressure compensators for hy- .draulic motori-pump units used `in engine starting Sys- Mike Prewarski, Serial No. 111,721, filed May 22, 1961,

,discloses a hydraulicstarting system including a motorpump unit ofthe overcenter type andgutilizing an accumulator as the source of motive `fluid .for the starting operation. The `displacement control elementrof the motor-pump unit is `urged toward one of its maximum displacement positions by 1a biasing means .and is shifted `toward the other `of .those positions by a fluid pressure control ,motor `whichis` vented fand pressurized by a icon- `trol valve that responds `to the pressure at the high pressure port of the unit. The biasing means, the control motor, and the control valve regulate the `displacement of the unit during the motoring operation and also serve `as `a `discharge .pressure compensator during the pumping operation. With a system such as this, where the ,controls for themotor-pump unit perform two functions, the pressure level established by the compensator `during the pumping operation is inherently limited to `.approximately the precharge pressure of the accumulator. Since it is desirable to `use the unit to rechargeV the accumulator during the pumping cycle, andl alsoto provide` fluid uudera higher. pressure for auxiliary uses,

the system includes means for selectively raising the presu .sure level to a higher value approximately equal tothe `fully charged pressure ofthe accumulator.

In some installations the motor-pump unit .of the Kent and Prewarski application is used `to start an auxiliary .engine .and then, when `that engine is 4running and driv- V ing, the unit `as a pump, asa `source of motive fluid for starting one or more main engines and for operating Someumes the Within desirable limits. As a result, the compensator t of the motor-pump unit must be set,fand that unit continuously operated, at a `pressure. materially 'higher than that 4deemed `most desirable for the` remaining components of the system even though the demands of the main engine starters are of `short duration. Obviously @this `is a disadvantage.

The object Aof this invention is to provide a discharge pressure compensator suitable for use on a` motor-pump unit of the type described in the -Kent and'Prewarski application which affordsthree fdischarge pressure levels.

According to the preferred embodiment of the invention,

`the compensator includes `a control valve that is biased `toward the supply position by` a spring seated ongaimov- 5 `able seat. As in the. control valve described in the Kent and Prewarski application, the seat [is moved from a low spring-load position to a high spring-load position by a fluid pressure motor in orderito` raise the level of the discharge pressure. The valve also includes a sec- The co-pending application of VMelvin L. Kent and United States Pate-nt ,setting at other times.

3,227,181 Patented Jan. 4, 1966 ond illuid pressure motor that acts in opposition ,to the spring ,and which, when pressurized, overpowers `the spring andin effect reduces the pressureat which the valve commences to pressurize the control motor and causes itto reduce displacement. With this typeof compensator, the motorpump unit need supply iluidat `the highestpressure level only when there is a demand for lluid at thatpressure. At other times, `fluid can be supplied at one of the lower pressure levels.

The invention also embraces a `novel startingsystem `incorporating -the ycompensator just mentioned and including `means for automatically energizing and de-energizing the two uid pressure motors inthe control valve. In `the preferred `form of this system, the motor-pump unit is connected with an auxiliary engine and is arranged` to supply motive fluid to hydraulic starters connected with the main engines. Motive iiuid is supplied `to the motor-pump unit from theaccumulator througha start valve that is so `interconnected .with the second lluid pressure motor in the control valve that `the latter ispressurized when the start Valve is opened and vented when the start valve is closed. In this way, the vControl valve is automaticallyadjusted toits lowest setting when `the motor-pump unit lis motoring and to its intermediate Motive fluid is supplied .to .each main engine starter from the motor-pump unit through .a start valve that isl so interconnected with the first uid pressure motor in the control valve that the latter is pressurized and vented when the start valve is `opened and closed, respectively. With this arrangement, the compensator is `set `to its highest level only whena main engine is being started. VIn .the preferred form of this system, all of the start valves are of the pilot-operated type .and their piloted` motors are connected with the corresponding liuid pressure motors inthe control valve. Thus, when the pilot valve` pressurizes and vents .the piloted motor to open .and close, respectively, thestart valve, it automatically .pressurizes and vents the fluid pressure motor that adjusts the setting -of the compensator. .The preferred embodiment of the `invention `is described herein with reference .to the accompanying drawjing -whose single figure is a schematic diagram of a typical ,engine starting system incorporating the invention.

As shown inthe drawing, the starting system includes an overcenter motorfpump unit 1 of the type described in the` Kent and Rrewarski application mentioned above,

whose drive shaft 2 is connected in driving and driven relation with auxiliary engine 3 and which is .arranged `to receive motive fluid from a gas-charged accumulator i. 4 and todeliver motive fluid to a starter motor 5 Iwhose drive shaft 6 is connected in `driving relation with main engine -7. Motor-pump unit 1 is of the rotary cylinder barrel, `longitudinally reciprocating piston type and in- `cludes high ,and `lowpressure ports 48 and 9 .and a -cam plate 11 which` is mounted for` pivotal movement about the axis of trunnionv 12. The low `pressure port 9 of .unit 1 `is in .continuous communication with reservoir 13 andthe high pressure -port 8 is connected with Vaccumulator 4 along two parallel paths, one path including conduits 1li, `14a and 14h and controlled by :auxiliary starter valve 1.5, and the other path including conduit 14,140,114161 and 14h and `containing a check valve V16. High pressure port 8 also is connected with a .hydraulic system including the power operated-devices,` (not shown) through` conduitsllt, 14a, 14e, and with the inletport 17 of motor. vS' through conduits 14,1441 and 147C. The

last mentioned connection is controlled by main. starter valve l5. `The discharge port 18 of motor 5 is in continuous communication with reservoir.13. The accumulatoriis charged initially by a hand pump `19 with which it is connected by conduit 14g containing a check valve 21.

Auxiliary starter valve 15 includes a main valve unit comprising inlet and outlet chambers 22 and 23 which are connected with conduits 14!) and 14a, respectively, and a sliding valve plunger 24 formed with an annular groove 25 that defines two valve lands 26 and 27. Valve plunger 24 is biased to the illustrated position by a coil compression spring 28 and in this position land 26 interrupts communication between chambers 22 and 23. The valve plunger 24 is shifted to the left to the open position in which groove 25 interconnects chambers 22 and 23 by a piloted motor comprising working chamber 29 and a piston which is dened by the right end of the valve plunger. The working chamber 29 of the piloted motor is selectively vented and pressurized by a pilot valve comprising inlet, outlet and

exhaust chambers

31, 32 and 33, which are connected, respectively, with conduit 14h, working chamber 29 and reservoir 13, and a sliding valve plunger 34 formed with an annular groove 35 that defines two valve lands 36 and 37. A coil compression spring 38 biases valve plunger 34 to the vent position in which land 36 blocks chamber 31 and groove 35

interconnects chambers

32 and 33. The plunger 34 is shifted to the left to the pressurizing position, in which land 37 blocks chamber 33 and groove 35

interconnects chambers

31 and 32, by a solenoid actuator 39. The coil of solenoid actuator 39 is connected in an electrical circuit with battery 41 and is selectively energized and de-energized by a switch 42.

Main starter valve 15 is identical to auxiliary starter valve 15 so its parts bear the same reference numerals with primes added for clarity.

The displacement of motor-pump unit 1 is controlled by cam plate 11 which is biased in the counterclockwise direction about the axis of trunnion 12 by a coil compression spring 43 which is seated on the outturned ilanges of a pair of

telescoping sleeves

44 and 45. Sleeve 45 is carried by a reciprocable piston rod 46 and is provided with a surface 47 which cooperates with the surface 48 on sleeve 44 to define a stop that prevents the cam plate 11 from moving in the clockwise direction from the zero displacement or neutral position during the pumping cycle. The cam stop is rendered effective, and the sleeve seat 45 is moved in a direction to increase the load in spring 43, by a piston motor 49 comprising a piston 51 and a working chamber 52. Working charnber 52 is selectively vented and pressurized by a selector valve S3 comprising inlet, outlet and

exhaust chambers

54, 55 and 56 which are connected, respectively, with conduit 14C, working chamber 52 and reservoir 13, and a sliding valve plunger 57 formed with an annular groove 58 that defines two valve lands 59 and 61.`

Valve plunger 57 is biased to the illustrated pressurizing position by a coil compression spring 62 and in this position land 59 blocks exhaust chamber 56 and groove 58

interconnects chambers

54 and 55. A solenoid actua tor 63 is provided for shifting valve plunger 57 to the left to the vent position in which land 61 blocks inlet chamber 54 and groove 5S interconnects

chambers

55 and 56. The coil of solenoid actuator 63 is selectively energized and de-energized by an electrical circuit including battery 41 and a switch 64 which is opened and closed in unison with switch 42. The details of the cam plate biasing spring and stop assembly are more fully described in the Kent and Prewarski application mentioned previously so further description here is deemed unnecessary.

Cam plate 11 of motor-pump unit 1 is moved in the clockwise direction about the axis of trunnion 12 against the bias of spring 43 by a control motor 65 including piston 66 and working chamber 67. Fluid is supplied to and exhausted from working chamber 67 under the control of a pressure responsive control valve 68 with Ywhich it is connected by conduit 69. Control valve 68 includes an inlet chamber 71 which is connected with the high pressure port 8 of motor-pump unit 1 through conduits 14h and 14, an outlet chamber 72 which is connected with conduit 69, an exhaust chamber 73 which is connected with reservoir 13 through passage 74 and spring chamber 75, and a sliding valve plunger 76 formed with two annular grooves 77 and 78 that dene three valve lands 79, 81 and 82. Valve plunger 76 is biased to the left toward the illustrated vent position, in which land 81 isolates inlet chamber 71 from outlet chamber 72 and groove 78 interconnects outlet chamber 72 and exhaust chamber 73, by a coil compression spring 83. The valve plunger 76 is shifted to the right, first to a lap position in which land 81 isolates outlet chamber 72 from chambers 71 and 73, and then to a supply position in which groove 77

interconnects chambers

71 and 72 and land 81 isolates chamber 72 from exhaust chamber 73, by the uid pressure in chamber 84 which acts upon the left end of the valve plunger. This charnber 84 is in continuous communication with the high pressure port 8 of unit 1 through conduits 141' and 1411.

The pressure in chamber 84 required to shift valve plunger 76 to the lap position against the bias of spring S3 is termed the reference pressure, and the control valve 68 includes two devices for raising and lowering this reference pressure. The first device, which is used to raise the reference pressure above the normal value, comprises a movable spring seat 85 for spring 83 which is shiftable between the illustrated low spring-load position and a high spring-load position in which it abuts stop 86, and a piston motor including the right end of seat 85 and working chamber 87. A conduit 88 interconnects working chambers 87 and 29 and, therefore, these working chambers are vented and pressurized simultaneously by the pilot valve of main starter valve 15. Control valve 68 is adjusted to establish its lowest reference pressure by a piston motor 89 comprising a piston 91 whose rod 92 abuts the left end of valve plunger 76, and a working chamber 93 which is connected with the working chamber 29 of starter valve 15 by a conduit 94. Therefore, motor 89 and working chamber 29 are vented and pressurized simultaneously by the pilot valve of auxiliary starter valve 15.

Like motor-pump unit 1, starter motor 5 is also of the rotary cylinder barrel, longitudinally reciprocating piston type. Preferably motor 5 is a variable displacement unit, but for simplicity, its controls are not illustrated. The co-pending application of Melvin L. `Kent and Edward V. Manning, Serial No. 119,170, iiled June 23, 1961, discloses a suitable design for this motor.

It might be mentioned here that in those cases when there are a plurality of main engines 7 that are to be started, each main engine is provided with a starter motor 5 and a starter valve 15. The inlet chamber 22 of the starter valves are connected in parallel with conduit 14a and a conduit 88 is provided between the piloted motor of each starter valve and the working chamber 87 of the control valve. Since the main engines in these cases are started in sequence, it is necessary to provide a restriction 95 in the vent conduit leading to the exhaust chamber 33 of each starter valve in order to develop a back pressure sufficient to shift the main valve plunger 24 in each starter valve to its open position and to shift the seat 85 to its high spring-load position.

Operation At the commencement of a starting cycle, the components of the system assume their illustrated positions so that motor-pump unit 1 is isolated from accumulator 4 by starter valve 15 and motor 5 is isolated from motorpump unit 1 by starter valve 15. Initially, accumulator 4 is charged with hydraulic fluid by hand pump 19. For purposes of discussion, it will be assumed that the precharge pressure of accumulator 4 is 1500 p.s.i., that the fully charged pressure of the accumulator is 3000 p.s.i.,

and `that lthe three reference pressures of `control `valve 68 are 1500 p.s.i., 3000 p.s.i., and 4000 p.s.i. l 1

In order to start auxiliary engine 3, the operator closes switch 42 to thereby energize solenoid actuator -39 and ca-use it to shift pilot valve plunger 34 to the left to its pressurizing position in which groove 35

interconnects chambers

31 and 32. Fluid from the accumulator 4 may now flow to the working chamber 29 of the piloted motor along a path comprising conduit 14b, chamber 31, plunger groove 35, and chamber 32 where it is effective to shift main valve plunger 24 to the `left to its open position in which groove 25 interconnects chambers 22 and 23. Simultaneously several other events take place.` First, closure of switch 42 also `eilects closure of switch 64 so that solenoid actuator 63 lis energized and shifts the valve plunger K57 of selector valve 53 to the left to the vent position in which motor 49 is vented to reservoir 13 through

chambers

55 and 56 and plunger groove 58. Second, fluid under pressure is delivered through conduit 94 to working chamber 93 in control valve 68 where it acts upon piston 91 and causes it to shift valve plunger 76 to the right to its supply position. This action sets control valve 68 to its lowest reference pressure of 1500 p.s.i. Since the valve plunger 24 of auxiliary starter valve 15 is open, fluid under pressure is now delivered to working 42 and 64, thereby de-energizing solenoid actuators39 chamber 67 of control motor 65 through conduits 14k,

14a,`14, 14h, chamber 71, plunger groove 77, chamber 72 and conduit 69. As a result, the control motor 65moves cam plate 11 in the clockwise direction to its maximum displacement position on the motoring side of neutral.

The lfluid supplied to motor-pump unit 1 from accumulator 4 through conduits 14h, 14a, 14 and high pressure port l8 causes the motor-pump unit 1 to develop torque and accelerate engine 3. As engine 3 accelerates, the pressure of the liuid delivered by accumulator 4 progressively decreases from 3000 p.s.i. to l500p.s.i. Since the combined forces developed by motor 95 and by the fluid pressure in chamber 84 acting'upon the left end of valve plunger 76 are suicient to hold the valve plunger in the supply position at pressures above 1500 p.s.i., working chamber 67 remains pressurized and control motor 65 'holds cam plate 11 in the maximum displacement position for the entire starting cycle. The parts of the system are so proportioned that the engine will reach ignition speed before accumulator pressure begins to approach 1500 p.s.i. and will reach or even exceed starter cut-out speed I(i.e., the speed at which the engine is capable of` developing sufficient power to accelerate itself) by the time accumulator pressure reaches 1500 p.s.i. Therefore, when the accumulator pressure decreases to 1500 p.s.i., and the accumulator is fully discharged, engine 3` will be running and accelerating at a rate greater than that of motor-pump unit 1. Consequently, at this time, system pressure will decrease momentarily below 1500 p.s.i. and

zero displacement or neutral position so that motor-pump` unit 1 commences to discharge fluid under pressure from high pressure port 8. This pumping action of motor-pump unit 1 restores system pressure to 1500 p.s.i. and, when the displacement of motor-pump unit 1 equals the rate of leakage from the system, valve plunger 76 will move to the right to the lap position and hydraulically lock control motor 65. Motor-pump unit 1 is now serving as a pressure compensated pump that establishes a maximum system pressure of 1500 p.s.i. Since the pressure lis relatively low and the displacement of motor-pump unit 1 is quite small, the load on engine 3 is small and it may accelerate rapidly to the speed at which it develops sutlicient power to start main engine 7.

At this point in the cycle the operator opens switches and `63. Spring 38 now shifts pilot valve plunger 34 back to the illustrated vent position in which working chambers 29 and 93 are connected to reservoir 13, and spring 28 shifts main valve plunger 24 to its closed position. Since motor 89 is now vented, spring 83 shifts control valve plunger 76 to its vent position against the opposing force developed by the fluid pressure in chamber 84, and spring 43 moves cam plate 11 to its maximum displacement position on the pumping side of neutral, i.e., spring 43 moves cam plate 11 into engagement with `stop 10. Simultaneously, spring 62 of selector valve 53 moves plunger 57 to its pressurizing position and fluid under pressure is transmitted from conduit 14 lto Vworking chamber 52 through conduit 14C, chamber 54, plunger groove 58 and chamber 55'. As explained in the Kent and Prewar-ski application mentioned above, piston 51 now moves spring seat sleeve 45 to its high spring-load position and renders the stop defined by

surfaces

47 and 48 effective to prevent cam plate 11 from being moved in the clockwise direction beyond the neutral position.

The fluid discharged by motor-pump unit 1 now passes through

conduits

14, 14e, 14d and 14h to accumulator 4, and, since control valve 68 is now setto establish a reference pressure of 3000 p.s.i., the accumulator 4 is recharged to 3000 p.s.i. When the accumulator 4 is fully charged, and assuming there is no other demand for hydraulic uid, system pressure tends to rise above 3000 p.s.i. and valve plunger 76 shifts to its supply position. Control motor 65, therefore, becomes effective to move cam plate 11rtoward the zero displacement position against the opposing bias of spring 43. Inasmuch as these systems always have some leakage, the cam plate 11 will come to rest, and control motor 65 will be hydraulically locked, when the system pressure is restored to 3000 p.s.i. and the displacement of motor-pump unit 1 equals the rate of leakage.

In order to start main engine 7, the operator closes switch 42' to energize solenoid actuator 39 and shift pilot valve plunger 34 to its pressurizing position. Fluid under pressure discharged by motor-pump unit 1 may now flow to working chamber 29 through conduits 14 and 14a, chamber 31', plunger groove 3S', and chamber 32 where it is effective to shift main valve plunger 24 to the left and open a flow path from conduit 14a to inlet port 17 of motor 5 that includes chamber 22', plunger groove 25', chamber 23 and conduit 143. Opening of this flow path imposes a demand on motor-pump unit 1 and produces a momentary drop in system pressure below 3000 p.s.i. Therefore, valve plunger 76 shifts to its vent position and spring 43 moves cam plate 11 toward its maximum displacement position on the pumping side of neutral.

Simultaneously, with the opening of main starter valve 15', -tluid under pressure is transmitted to Working charnber 87 through conduit 88 where it is effective to shift spring seat 35 to the left into engagement with stop S6. This shift of the spring seat increases the preload in spring 83 and, therefore, raises the reference pressure of valve 68 to 4000 p.s.i. Starter motor 5 now commences to accelerate engine 7 to cut-out speed.

After engine 7 has been started and reaches starter cutout speed, switch 42 is opened to tie-energize solenoid `actuator 39' and allow spring 33 to move pilot valve.

plunger 34 to its illustrated vent position. Working chambers 29 and 87 are now exhausted to reservoir 13 through chamber 32', plunger groove 35 and chamber 33', thereby allowing spring 2S to close the main starter valve and allowing spring S3 to move seat 85 back to its low spring load position. Since this action reduces the reference pressure of control valve 68 to 3000 p.s.i., the fluid pressure in chamber -84 immediately moves valve plunger 76 to its supply position (assuming that the system is imposing no demand on motor-pump unit 1 at this time). Control motor 65, therefore, moves cam plate 11 in the clockwise direction to a reduced displacement position in which the displace nent of motor-pump unit 1 equals the rate of leakage and system pressure is maintained at 3000 p.s.i.

Motor-pump unit l is now available to supply the various demands connected with conduit 14e and it will be understood that in handling these demands, as well as those of starter motor S, the compensator including control Valve 68, control motor 65 and spring 43 will vary the angular position of cam plate l1, and consequently, the displacement of motor-pump unit 1, in inverse relation to system pressure so that that pressure is maintained substantially constant at the selected reference pressure.

It might be mentioned here that in some cases, for eX- ample when the ambient temperature is relatively high, the torque demand of engine 3 may be such that the entire capacity of accumulator 4 is not required during the starting cycle of this engine. In these cases, engine 3 will reach starter cut-out speed when accumulator pressure is still considerably above '(for example, several hundred p.s.i. above) the lowest reference pressure of 150() p.s.i. Under these conditions the operator may interrupt motoring operation of motor-pump unit 1 by opening switch 4Z. This action results in closure of the auxiliary starter valve 15, in shitting of selector valve 53 to its pressurizing position, and in adjustment of control valve 68 to its intermediate reference pressure of 3000 p.s.i. Therefore, Valve plunger '76 of the control valve 68 moves to the vent position and spring 43 pivots cam plate 11 in the counterclockwise direction to a small displacement position on the pumping side of neutral. Motor-pump unit 1 now operates as a pump compensated to 3000 p.s.i. in the manner previously described. In the alternative, the operator may allow motor-pump unit 1 to accelerate engine 3 to a speed materially higher than starter cut-out speed and permit the controls to shift cam plate ll in the counterclockwise direction automatically as in the case tirst described. However, in this event, the motor-pump unit 1 must oe designed to withstand the overspeed condition.

As `stated previously, the drawing and description relate only to the preferred embodiment of the invention. Since changes can be made in the structure of this embodiment without departing from the inventive concept, the following claim should provide the sole measure of the scope of the invention.

What I claim is:

A valve comprising I(a) a housing containing inlet, exhaust, and outlet passages;

( b) a valve member shiftable between Vfirst and second positions in which, respectively, the outlet passage is connected with the exhaust and inlet passages, and having an intermediate lap position in which the outlet passage is isolated from both the inlet and exhaust passages;

(c) a spring biasing the valve member toward the rst position;

(d) means responsive to the pressure in the inlet passage for urging the valve member toward the second position;

(e) a movable spring seat for the spring shiftable in spring load-increasing and spring load-decreasing directions;

`(t) a first tluid pressure motor connected with the spring seat and arranged to shift the seat in the loadincreasing direction; and

'(g) a second iluid pressure motor acting in opposition to the spring.

Reterences Cited by the Examiner UNITED STATES PATENTS 2,803,266 8/1957 Towler et al. 137-625.66 X

M. CARY NELSON, Primary Examiner.