US2661020A - Fluid pressure control apparatus for free piston machines - Google Patents

Description

Dec. 1, 1953 I A. J. BENT 20 FLUID PRESSURE CONTROL APPARATUS FOR FREE PISTON MACHINES Original Filed Jilly 22, 1947 IN VEN TOR.

By Arihur JBent ATTORNEY piston is what ma Patented Dec. I, 1953 PRE SSURE CONTR L APPARATUS i-EORQFREEPISTON MACHINES -'-Ai thur 3i. Ben't, Tenn Township, Allegheny 'Gou'nty, Pa., assignor 1:0 Westinghouse Air BrakesGompainy, arcorporation of :Pennsylvania b f-iginal "application -July 22, 1947, Serial .No. ."H1"2;,"7"Z1 ,"now Patent No. "2,608,052, dated August 26, 1952. V "Divided and this application il'un'e 15, 1948, Se'lial N 0. 33,044

.lI hisI'inventiomrelatese toscontrolzapparatuszfor jfreepiston machines ;;particularly: of: thezgasggen- .erator type, embodying ;two :oppos'itelyiarranged motorzoperated'fair: compressor portionseach embodying an 7 internal tcdr nbustion :ope'rated ;power .pistonrandacoaxial-lyarran'ged anti rigidly Iconnested air "compresscr :piston 'iiperative by "said powerz'piston T t0 compress airifor scavenging and 'feed of the motoripart of the machine and in which the =miizture'fofthe ilidt gase's ofscdmbustion and "of the excess of .vgcavenger'air discharged from ttheiimotor I'pait "of the machine form :together i'generated :motive gas which may' be employedto perform mechanical worktasby expansion. in a"turbin'e,;the:present application bein'g a division of "my :coiaending application serial No. 762177 1, :filed Jilly 22, $19.47, .fnow Patent No. 2,608,052, issuedAligustfi6;fl952.

vIn Patent 3N0. 12,406,037 1 issued dn 'August 20, 1946, to R. P. Ramsey there is disclosed a free piston: machine iof *this igeneral type which embodies "two ioppositely a d coaxially arranged motor compressor-cunitseach emlcodying-af piston assembly comprising a power pistonmn air 'com- "pressor'piston'and a direct' bounce piston. Be-

tween the two power pistons is a power or combustiOnYchamber intD which fu'el is adapted t'o be injected for compressionignition-Tor -driving's'a-id pistons apart. th'e oiiter face of e'ach aircompressoripistoniis an air ompressingchamber and said piston is operative by the respective-power piston zto compress *a'i'r i'r oin -said chan'1b'er into a scavenger "receiver 1 fd'r -the urpose *ajbove set forth. :At l thef out'er frace of=-each direct bounce e called -?a direct bounce chamberZ iHWhich-ai adaptedto becomipressed upcn the ai'ricoih" re'ss'iiig stranger *therespetive power piston "nergyfor 'turning the toits inner position "preceding mother mowerst oke.

"amount cif air necessary in the direct fl'aounce fuel supply to the combustion chanib'erfmust-be vention.

:bounceigovernor idevice controlled :by' pressureeof air inithe scavenger receiver-and the-stroke ofrthe piston assembliesfor automaticall-yso regulating the amount of air inthedireet bouncechambers.

Other objectsvand advantages'will appearirom the following more detaileddescriptionpf the in- In the accompanying drawing "the 'singlevfigur'e is a diagrammatic,-:sectional"view of a directfbounce'igovernor -='dev-ice embodying the invention.

.-DES.CRIPTION As shown in the drawing, :thedirect .bounce governor device comprises ia"fluid-;pressure regulating mechanism "359:150-1' controlling the "pressure of-fiuid in thedirect"bouncechambersof a free piston gas'generatorKnot-shown) and"a:control portion 3 5 [for "controlling operation "of said regulating mechanismsaid mechanism and control portion'comprising acommon casingrse'ction 352 mounted on apipe bracket"353 'and'the said mechanismcomprising in addition a .casing sec- 'tion 354a mounted'on the casing section 352.

"The fluid pressure regulating mechanism 350 comprises a supply valve 355 contained in 4a 'chamber '6and"arranged to cooperate with a seat '3'57for controlling flowof fluidunder pressure fro'm chamber 356 to" an outlet chamber 358 provided in bracket F353. A guide member 1359 projecting above theseat. 35'! is provided 'witha tapered 'openin'gfor receiving'the valve;355 to guide it to its seat and toalso'cooperate withisaid valve when in said opening "to throttleflow of "fluid underpressure "from chamber 356 to the toxbeicon'stanflysupplied-via apipe 356 with? fiuid under pressure Ffrom :@any suitable source. The outlet rchamberi z iifis: is Iopen'to: a 'pipe 33 0 adapted to beconnectedi.to:'the:direct 'bounce chambers in theifreegpistoni gas "generatori lfnots'shown) iTheesupply --va-1ve :3 .i-is connected LtOiTthGF-GHd ,of aestemz-3fi l by raj pin 362, said stem: projecting fromtapcontrol pistonr-3 63operat-ive1y mountedxin a bushing v364v held: in position-between'theicasing sections352.. and 4354a. -A-n eequalizing port 3.65 through the bushing. 354 ,iscprovided :to; per- .mit equalization of fluid pressureiromchamber 356 intolia chamber 3 E56.v at ;the. stemside. of the piston 363. Atthe opposite 'side ofc.'the .pistom363 is 'a' control "chamber 36'! open 'througmarchoke 368,2; strainer 3 69 and a passage'3fi9ain thelpistonstem' 36l to chamber 356. 'A'spring follower 356armountedpmthe 'stem "36 l in contact with valve 1-355 is engaged by :one" end "of #a precompressed spring 368a the 76111181 end or which is supported byr the' bushing'ESBMsaid spring being Q3 provided for closing said valve upon substantial equalization of pressure of fluid acting on opposite sides of piston 363.

Disposed in the casing section Side: is a valve seat member tlil held in place by a retainer till secured in said casing section. The seat member Slil has a bore open at one end to a passage 3'52 leading to the outlet chamber 358 and to the control portion 35! of the direct bounce governor device. The opposite end of this bore opens through a valve seat 373 to a chamber 314 which in turn is connected through one or more ports 315 in retainer 3'75 to the control chamber 561 at the one face of piston 363. Slidably mounted in a bore in the retainer 31! coaxially of the valve seat 3 .3 is a valve 316 arranged to cooperate with seat 313 for closing communication between chamber 3M and passage 3'l2. A plunger 31! slidably mounted in a bore in a partition wall Bit has an extension 319 of smaller diameter than the axial bore in seat member 318 and extending therethrough for contact with the valve 3'36 for unseating it against a spring 38% carried by the retainer 315. The plunger 37'! is provided on its opposite end with a projection 3&2 extending into a chamber 3% for cooperation with a valve 383 which is slidably mounted in a bore 38% arranged in coaxial relation to said plunger Ell in an element 385 secured in the casing. The valve 383 may be provided with slots 386 around its edge to provide communication between opposite sides thereof. The char).- ber 382 is open through a port 387 to passage 312 and thereby to the outlet chamber 358.

A cover 3% is clamped to the end of the casing section 35% opposite that engaging the casing portion 352, and clamped between said cover and the casing section 35 3a is a flexible diaphrag a 3% arranged in coaxial relation with the bore 3% in the element 385. phragm is a control chamber 396 in which the element 385 is disposed. At the opposite side of the diaphragm is another control chamber 3%! The chamber 396 is open through a passage 392 to a pipe 3% adapted to be connected directly to one of the direct bounce chambers in the gas generator (not shown), a chosen restriction to flow of air through this communication being provided as by said pipe being of relativeh small flow capacity. The chamber 395 is open through a choke 39 i and a passage 3&5 directly to the fluid pressure supply pipe 354.

A diaphragm follower 3% disposed in chamber 39%! engages the adjacent face of diaphragm 389 and has a portion 39? extending through a central opening in said diaphragm and a follower 3&5 disposed in chamber 3%! against the opposite side of the diaphragm, and these followers are rigidly clamped to opposite sides of said diaphragm by a securing element 398 engaging the follower 398 and having internal screw-threaded engagement with the portion 39'! of the follower 396.

The diaphragm follower 396 has an integral member tilt disposed in the bore 3% in the element 385, said member 4% having a spherical like surface in sliding contact with the wall of said bore and carrying a sealing ring lili having sealing contact with said wall. On the innermost end of the integral member 408 is formed a valve seat 492 arranged for sealing engagement with the valve 333. A shoulder 403 substantially en circling the valve seat tilt and projecting from the wall of bore 334 is provided for contact by valve 333 for unseating said valve from the mem- At one side of this diad ber 40! upon movement of said member in the direction away from said valve.

The valve seat tilt encircles a fluid pressure release passage 4% extending through the integral member Mill and the follower 3% to a chamber 4B5 provided at the opposite side of the diaphragm 339 in a coaxially arranged cylindrical portion 465 of the securing element 3589. Slide mounted in the cylindrical portion tilt is one of a rigid strut till the opposite end of which is slidably mounted in a bore in the casing cover 33%, which bore is normally in coaxial relation with the cylindrical portion sec. The strut M! has an axial bore tilt! establishing communication between chamber M5 and a passage in the casing cover 3% which passage opens to at mosphere. The opposite end portions of the strut M31 in contact with the wall of the bore in the casing cover 3% and with the wall of the cylindrical portion @656 are rounded to permit free slight inisalignments or wobbling or the diaphragm 389 during movement thereof, which will be later described, and in each end of said strut is a sealing ring (lit having sealing slidi .v contact with the respective wall for preventi g leakage of fluid under pressure from the control chamber 3%! to the atmospheric passage M29.

The diameter of the rigid strut lm at its point of contact with the cylindrical portion ti t of the securing element 399 is greater than the diameter of the integral member see at the opposite side of the diaphragm which is disposed in the bore 334, whereby less area of the diaphragm 389 is subject to pressure oi fluid in chamber 39! than is subject to opposing pressur of fluid in chamber 396, in order that a lower press of fluid in the latter chamber will provide a felt: to balance a higher pressure of fluid in the to ac chamber during operation, to be hereinaf described.

The control portion tfil of the direct bou governor device comprises a flexible diaphra Ml secured around its edge between the casmsection 35l and the cover H2. Between the co H2 and the diaphragm Mi is a control chamber M3 open through a passage di t to a pipe ilt adapted to be connected to the scavenger air receiver of the free piston generator (not shown At the opposite side of diaphragm ii 5 is a charcher M6 which is open to atmosphere through a vent port 411.

A follower H8 disposed in chamber 55 against the adjacent face of diaphragm til has a portion M9 extending centrally through the diaphragm into chamber H3 and over this portion in the latter chamber is mounted a follower plate iZd against the diaphragm and a nut 42! having screw-threaded engagement with said stud portion for clamping the central portion of the diaphragm between the follower tit plate 428. A regulating spring 522 contained in chamber 415 and supported at on end on the casing section 352 bears against the diaphragm follower lli; urging the diaphragm ill in the direction of cover M2.

The casing section a bore arranged in coaxial relation with the diaphragm til i and containing a plunger 52%. The plunger 323 is provided on the end adjacentthe diaphragm lit with a stem 62% extending through a chamber G25 and an axial bore in a bushing 52% secured in the casing section 352, into chamber lit and thence through said chamber into contact with the diaphragm follower 333. Adjacent to the follower H364 washer dill is secured to plunger through choke 394 and provide a force on dia phragm 389 which will move same in the direction of chamber 3% for thereby actuating the integral member its into seating engagement with the valve 383 and for then shifting said valve against plunger 3's"? to unseat the valve 336. Upon unseating of valve 3'55 the chamber 361 at one side of the control piston 363 will be opened past said valve to passage 372 and thence to the outlet chamber 353 which may be open to the direct bounce chambers in the gas generator (not shown). The pressure in the supply piston chamber will thereby be reduced sufficiently below the supply pressure in chamber 239 to provide a force on the piston to move same in a direction to pull the supply valve 355 away from the seat whereupon fluid under pressure from the supply valve chamber 356 will flow to the outlet chamber and thence to the direct bounce chambers in the gas generator.

As fluid under pressure is thus supplied to the direct bounce chambers in the gas generator (not shown) it will equalize through pipe 393 back into diaphragm chamber 3% in the direct bounce governor device and thereby provide a force on diaphragm opposing pressure of fluid in chamber Elli. Since the area of diaphragm 385 subject to pressure of fluid in chamber 3% is greater than that subject to pressure of fluid in chamber 39!, it will be seen that when the pressure in the former chamber becomes increased to a degree somewhat less than that acting in charmber 39! said diaphragm will deflect in the direction of the left hand to permit closing of valve Bit by spring 3%.

When the valve 31's in the direct bounce governor device is closed as just described, fluid at the supply pressure in chambers 35 3, 356 at one side of piston 3&3 will promptly equalize through the passage Etta and choke see into piston chamber whereupon spring 388d will actuate said piston to close the valve 355 for preventing further flow of fluid under pressure to the outlet chamber and thereby to the direct bounce chambers in the gas generator and back to charm her 32- l Now let it be assumed that the tappet 22 is periodically operated to unseat the valve 581, assuming the diaphragm ii A and valve seat did to be in the position in which they are shown in the drawing. This periodic unseating of valve 33'? will release fluid under pressure from chamber 395 to chamber which is at lower pressure. The venting capacity of valve it? is so in excess of the flow capacity or" choke to supply fluid under pressure to chamber 39! that the pressure in said chamber will become reduced by the periodic unseating movements of valve 53! and hence permit pressure of fluid in chamber 355 to deflect the diaphragm see in the direction of the lower pressure in chamber 3% l such movement unseating the release valve to permit release of fluid under pressure from chamber 353 and the connected chamber When the pressure in thus becomes reduced sufliciently pressure of in chamber its-i will deflect diaphragm 55233 to close the release valve 383 for thereby limiting the pressure in chamber 3% to substantially the reduced degree acting in chamthe length of time which the valve :33? will be unseated for each movement of said tappet will be correspondingly greater resulting in a corresponding further reduction in pressure in chamber 39! and thereby operation of diaphragm 38?;

to open the release valve 383 to cause a like reduction in pressure in chamber 391]. The pressure in chamber 390 will thus be reduced in accordance with the increase in pressure in chamber M3, on diaphragm All due to the proportion" ally increased time which the valve as? is off its seat 436. On the other hand, if the pressure of fluid in chamber M3 is reduced the seat 535 will be moved closer to valve 43! so that the length of time which said valve will be oil its seat during reciprocation of tappet 22 will be correspondingly reduced. As a result the pressure in chamber 39! will be increased by the supply through choke 3% relative to the pressure acting in chamber 39c and thereby cause deflection of diaphragm 389 to open the supply pilot valve 318. As before described, piston 363 will then open the supply valve 355 to increase the pressure or fluid in chamber 358 and thereby in chamber sec correspondingly, whereupon the diaphragm 388 will be deflected by fluid in the latter chamber to permit seating of the supply pilot valve 3'56 and thereby closing of the supply valve to prevent further supply of fluid under pressure to chamber 358.

If the length of stroke of tappet 22 is increased the same result will occur as in case of increasing pressure of fluid in chamber 413, while if the length of said stroke is shortened. the pressure in chamber 358 will be increased the same as if pressure of fluid in chamber M3 is reduced.

It will therefore be seen that the fluid pressure regulating mechanism 35c will operate to vary the pressure of fluid in chamber 353 in accordance with operation of the control portion 3% or" the governor as controlled by pressure of fluid in chamber M3 and the length of reciprocating stroke of tappet 22. As applied to a free piston gas generator where chambers 3.58 and see are open to the direct bounce chambers, chamber flit is open to the scavenger receiver for subjecting diaphragm all! to pressure of fluid delivered by said generator, and tappet 2c is arranged. for reciprocation by the generator pistons near the end of their inward stroke, the direct bounce governor device will therefore automatically vary the amount of fluid under pressure in the direct bounce chamber of the generator as necessary to maintain a desired stroking of the generator pistons.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. A valve device for governing the quantity of fluid under pressure in a chamber comprising a casing, a supply valve cooperative with a seat in said casing fo controlling supply of fluid under pressure to said chamber, a release valve slidable in a bore in said casing in coaxial relation to said supply valve, means connecting said valves for movement in unison, seating means for urging said supply valve to its seat, a flexible diaphragm in said casing arranged in coaxial relation to valves and subject on one side to a variable control fluid pressure in a control chamber, follower means secured centrally to and movable with said diaphragm, seat means for said release valve movable with said follower means and disposed in said bore in sliding and sealing contact with the wall thereof, said follower means having a a sess s cavityva'and' a passage connecting said =cavity;to.-, said seat means, said release .valve;..controlling-.. communication betweenthe first named chamber:- and said passage, conduit meansconnectingisaid cavity with an atmospheric opening incsaidcasa ing, and means subjecting the-opposite sidesof. said diaphragm to pressure of fluid from. thexfirsti named chamber whichopposes .pressureofzfluid's acting on said diaphragm in saidcontroli chamet ber; said diaphragm being operative uponea pres. ponderance in pressure in .saidicontrol, chamber over the-opposing pressure.:of'*fiuid-:to -seatasaid, release valve and open said supply valve and upon a preponderance in said opposing pressure of fluid ,over; that. in said control chamber, to, ,rngve said seat means .outoi seating cooperation with said release valve and" to permit-seating of said supplyvallve by said seatingvmeans.

2". A valve deviceior governingithe quantity-oi fluidunder pressure-in chamb'eri comprisina; casing, a supply-valve cooperative-with ass-cam said casing for controlling supply of fluid under. pressure to said chamber, a1releasevalve slidable in aborein said casing in coaxial relation to said supply valve, means connecting said valves for movement in unison, seating means for urging said Supply valve to its seat, a flexible diaphragm in said casing arranged in coaxial relation to said valves, follower means secured centrally to and movable with said diaphragm, seat means for said release valve movable with said follower means and disposed in said bore in sliding and sealing contact with the wall thereof, said follower means having a cavity and a passage connecting said cavity to said seat means, said release valve controlling communication between said chamber and said passage, conduit means extending through a fluid pressure control chamber at one side of said diaphragm connecting said cavity to an atmospheric opening in said casing, means subjecting the opposite side of said diaphragm to pressure of fluid from the first named chamber which opposes pressure of fluid acting on said diaphragm in said control chamber, said diaphragm being operative upon a preponderance in pressure in said control chamber over the opposing pressure of fluid to seat said release valve and open said supply valve and upon a preponderance in said opposing pressure of fluid over that in said control chamber to move said seat means out of seating cooperation with said release valve and to permit seating of the supply valve by said seating means, choke means providing a constant controlled rate of supply of fluid under pressure to said control chamber, variable operable means for releasing fluid under pressure from said control chamber and automatically operative variable stroke means for controlling operation of said variable operable means to thereby vary the rate of release of fluidunder pressure from said control chamber with respect to the constant rate of supply to thereby regulate pressure of fluid in said control chamber.

3. A valve device for governing the quantity of fluid under pressure in a chamber comprising a supply valve for supplying fluid under pressure from a source to said chamber, a piston connected to said valve and subject on one side to pressure of fluid in said source and on the opposite side to pressure of control fluid in a control chamber, and operative upon a reduction in the latter pressure to open said supply valve, a restricted passage connecting opposite sides of said piston for equalizing the fluid pressures on said opposite sides, spring means for closing said supply valve 1 underrpressure; from: said chamber to, provide, a;

pressure therein corresponding to the length of 10 upon; equalization of: fiuid apressures on: saidiopz positesides; aisupply pilot valvefor. releasingifluid under pressure from said control chambento the first named chamber-,- a releaselvalve.arrangedin;

leasing fiuid-under pressure from: said first named; chamber, movable; abutment means subject to; fluidsunderpressure.from said-first named chain: ber and: to an opposing; variable 1 control fluidpressureiin. a-seeond control chamber, andimeans operable-by said"; abutment. means upon a DIE-.- ponderance: in. pressure in. said; second; control: chambenoyer the-opposing fluid pressure to close; said release valve and ropen said-rsupplylpilot valve and-'upcna preponderance in :pressurerromsaid first: named chamberover that; in; said second; control ichambereto effect closing. of .;said supply; PiIQtiVEJVf-l andiopeningl.ofi-saidirelease;valve;

4.: Ar. valve; device comprising means .provi.ding aiconstantaflowl,.-of.rfluid under; pressure to. a..con:-

'trol :chamber, aqfluid pressure release; passageway; OQHIIGGEGd-Tlld said chamber, coope ting. valve;

andivalverseat,elements controlling. communi tion. through;saidipassageway. for releasingfl time said elements are unseated one from the other, pressure means responsive to variations of pressure of fluid for accordingly positioning one of said elements, and reciprocating means for intermittently unseating the other element from said'one element.

5. A valve device comprising means providing a constant flow of fluid under pressure to a chamber, cooperating valve and valve seat elements controlling a communication connected to said chamber for releasing fiuid under pressure from said chamber to provide a pressure therein corresponding to the length of time said elements are unseated one from the other, a regulating spring, a movable abutment subject to pressure of said regulating spring and opposing pressure of fluid adjustable to a position corresponding to the pressure of such fluid, means connecting one of said elements for adjustment by said abutment, and operating means for intermittently moving the other valve element out of seating contact with said one valve element.

6. In combination, valve means for selectively supplying fluid under pressure to and releasing fluid under pressure from a chamber, movable abutment means controlled by opposing pressures of fluid in a first chamber and in a second chamber which is adapted to be open to the first named chamber, and operative upon a preponderance in pressure in said first chamber over that in said second chamber to effect operation of said valve 7 means to supply fluid under pressure to the first named chamber and upon a preponderance in pressure in said second chamber over that in said first chamber to erIect operation of aid valve means to release fluid under pressure from the first named chamber, fluid pressure adjustable means and reciprocable means cooperable with said fluid pressure adjustable means for controllingpressure of fluid in said first chamber.

7. In combination, valve means for selectively supplying fluid under pressure to and releasing fluid under pressure from a chamber, movable abutment means controlled by opposing pressures of fluid in a first chamber and in a second chamber which is adapted to be open to the first named chamber, and operative upon a preponderance in pressure in said first chamber over that in said second chamber to effect operation of said valve means to supplyfiuid under pressure to the first named chamber and upon a preponderance in pressure in said second chamber over that in said first chamber to efiect operation of said valve means to release fluid under pressure from the first named chamber, relatively movable valve and valve seat elements cooperative to vary pressure of fluid in said first chamber according to extent of movement of one of said elements relative to the other, fluid pressure adjustable means for positioning said other element in accordance with the pressure of such fluid, and reciprocable means for periodically moving said one element relative to said other element.

8. In combination, valve means for selectively supplying fluid under pressure to and releasing fluid under pressure from a chamber, movable abutment means controlled by opposing pressures of fiuid in a first chamber and in a second chamber which is adapted to be open to the first named chamber, and operative upon a preponderance in pressure in said first chamber over that in said second chamber to eiiect operation of said valve means to supply fluid under pressure to the first named chamber and upon a preponderance in pressure in said second chamber over that in said first chamber to effect operation of said valve means to release fluid under pressure from the first named chamber, relatively movable valve and valve seat elements cooperative to vary pressure of fluid in said first chamber according to extent of movement of one of said elements relative to the other, fluid pressure adjustable means for positioning said other element in accordance with the pressure of such fluid, and variable stroke reciprocable means for periodically moving said one element relative to said other element.

ARTHUR J. BENT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,047,581 Grissert July 14, 1936 2,376,671 Dodson May 22, 1945 2,401,680 Eaton June 4, 1946 2,411,748 Kelly Nov. 26, 1946 2,432,705, Williams Dec. 16, 1947 2,512,013 Down June 20, 1950

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