US3058453A - Fuel injector-igniter - Google Patents

Description

Oct. 16, 1962 c. H. MAY

FUEL INJECTOR-IGNITER Oct, 16, 1962 c. H. MAY 3,058,453

FUEL INJECTOR-IGNITER Filed Feb. l5, 1960 3 Sheets-Sheeil 2 'n am fgagf@ r mum/g rae This invention relates generally to internal combustion engines and more particularly to a novel fuel injectorigniter for an internal combustion engine.

This application is a continuation-in-part of my copending application Serial No. 8,784, filed February l5, 1960, entitled Fuel lnjector-Igniter.

As explained in greater detail in my aforementioned copending application, a pronounced improvement in internal combustion systems may be obtained by effecting ignition of the fuel used to supply energy to the system immediately prior to introduction thereof into a combustion chamber or working cylinder. The present invention provides a structure for accomplishing such ignition of the fuel in a manner somewhat different from that disclosed in my copending application. f

Accordingly, the broad object of the present invention is an improved combustion system for an internal combustion engine.

Another object is a combustion system that provides for the concurrent ejection and ignition of fuel.

Another object is a combustion system wherein ignition occurs at the onset of fuel injection and is of a continuous nature thereafter precluding ignition lag or delay of ignition within the expansion chamber.

Another object is a fuel injector-igniter having selfcontained fuel metering means.

Another object is a fuel injector-igniter having a selfcontained fuel metering means controllable solely by fuel pressure.

Other objects and advantages of the present invention will become apparent from the following detailed description wherein reference is made to the drawings, in which:

-FIGURE l is a sectional side elevational view of a fuel injector-igniter in accordance with one embodiment of the present invention;

F.lG. 2 is a sectional side elevational View taken along the line 2-2 of FIG. l;

FIG. 3 is a fragmentary sectional view of the fuel injector-igniter of FIG. l, enlarged for clarity;

FIG. 4 is a fragmentary sectional view of the nozzle portion of the fuel injector-igniter of FIG. 1, enlarged for clarity; and

FIG. 5 is a sectional view of a modified form of a fuel metering system usable with the fuel injector-igniter of the present invention.

A fuel injector-igniter 10, in accordance with an exemplary embodiment of the present invention, comprises a tubular housing or cylinder 12, having a lower end 14 with a threaded portion 16 thereon for engagement with a suitably threaded portion 17 of a nozzle retainer 18. The nozzle retainer 18 has a transversely extending end or cap portion 20 and a downwardly extending neck portion 22 having a central bore 23 therein. The neck portion 22 of the nozzle retainer 18 has a threaded portion 24 so as to be engageable in a suitably threaded aperture, for example the spark plug aperture 26 of a cylinder head 27 of a conventional internal combustion engine (not shown). A suitable sealing washer 28 is disposed in a peripheral recess 29 in the nozzel retainer 18 to eifect a uid seal between the nozzle retainer 18 and the cylinder head 27.

A nozzle 30, having a longitudinally extending upper end portion 31 of substantially the same diameter as Patented oct. 1e, 1962 the inside diameter of the cylinder 12 so as to be closely engagable therewith, is supported between the nozzle retainer 18 and the cylinder 12. The upper end portion 31 of the nozzle 30 has a downwardly convergent inner face 32 that terminates in a downwardly convergent conical pintle seat 34 (FIG. 4). The pintle seat 34 communicates with a vertically extending orice 36 that communicates with a downwardly divergent nozzle 38 in a downwardly extending tubular extension 40 of the nozzle 30. The extension 40 is accepted in the bore 2.3 of the nozzle retainer 18. The downwardly convergent conical pintle seat 34, in conjunction with the orifice 36 and downwardly divergent nozzle 3S `define venturi for the passage of burning fuel, as will be described hereinafter.

A counterbore 41 is provided at the upper end of the bore 23 adjacent an upper end face 42 of the nozzle retainer 18 for the acceptance of a suitable sealing washer '43 that, in conjunction with a similar washer 44 disposed between an annular lower end face 45 on the cylinder 12 and a peripheral flange 46 on the nozzle 30, functions to seal the nozzle 30 with respect to the cylinder 12 and nozzle retainer 18 against the passage of fluids.

A plunger 60 is disposed for reciprocal movement withing the cylinder 12 for the compression of air in a compression chamber 62 deued by a downwardly convergent conical bottom face 64 on the plunger 60 in combination with the downwardly convergent conical upper end face 32 of the nozzle 30 and an inner wall 66 of the cylinder 12. The diameter of the plunger 60 is substantially the same as the diameter of the inner wall 66 of the cylinder 12 to effect a lluid sealing fit therebetween. Air is admitted into the chamber 62 through a plurality of apertures 68 spaced radially around the cylinder 12 that are uncovered by the plunger 60 when the plunger 60 is in its uppermost position ('FIG. 2). Downward movement of the plunger 60 within the cylinder 12 closes off the apertures 68 thereafter compressing air within the chamber 62.

The plunger 60 is of generally U-shaped vertical crosssectional configuration having a bight portion 70 and a pair of upstanding leg portions 72 and 74. The leg portions 72 and 74 are retained radially with respect to one another by a plunger cap 76 having a central aperture 77 extending therethrough for a reason to be discussed. The leg portions 72 and 74 of the plunger 60 are of arcuate horizontal cross-section so as to be slidably acceptable within the cylinder 12. The leg portions 72 and 74 have thickened upper end portions 78 and 80, respectively, with downwardly extending ribs 82 and 84 thereon for locking engagement with a pair of complementary upwardly extending - arcuate ribs 86 and 88 on a pair of spring spacers 90 and 92, respectively. The spring spacers 90 and 92 are of arcuate horizontal cross-section so as to be slidable longitudinally of the cylinder 12 in closely spaced relationship to the outer peripheral surface thereof. The cylinder 12 is therefore acceptable between the concentric leg portions 72 and 74 of the plunger '60 and the spring spacers 90 and 92, respectively.

The plunger 60 is normally biased upwardly with respect to the housing or cylinder 12 by an operating spring that extends between an annular lower end face 102 on a spring retainer 104 and an upper end' face 105 on the nozzle retainer 18. The spring retainer 104 has a circular groove 106 therein for the acceptance of complementary ribs 108 and 110 on the spring spacers 90 and `92, respectively. Therefore, the upward bias of the operating spring 100 locks the spring retainer 104, and the spring spacers 90 and 92 to the upper end portions 73 and 80 of the plunger 60.

Referring to FIGURE 2, the cylinder 12 has a radially outwardly extending flange portion 122 that delines a. transversely extending annular seat 124 for the seating of a pump holder 126. The pump holder 126 has a lower end face 128 that is engageable with the seat 124 to limit downward movement of the pump holder 126 with respect to the cylinder 12. The pump holder 126 is biased against the seat 124 on the flange 122 by a radially 1nwardly extending ange 129 on a locking ring 130 having a central aperture 131. The locking ring 130 is threadably engageable with a suitably threaded portion 132 on the upper end portion 134 of the cylinder 12. rThe upper end portion 134 of the cylinder 12 is spaced radially outwardly from the cylinder 12 and from an intermediate cylindrical portion 135 by a transverse flange 136 that extends radially outwardly between the upper end portion 134 and the tubular longitudinally extending portion 135.

Referring to FIGURE 3, a pump housing 160, having an upwardly extending tubular wall portion 162 and a transverse lower end wall 164 is disposed centrally of the plunger 60 and pump holder 126. The side wall 162 of the pump housing 160 has a threaded portion 16S thereon for threaded engagement in a suitably threaded bore 166 in the pump holder 126. It is to be noted that because the pump holder 126 is seated against the end face 124 on the cylinder 12, rotation of the pump housing 160 with respect to the pump holder 126 effects an axial movement of the pump housing 160 with respect to the cylinder 12. This axial adjustment of the pump housing 160 with respect to the cylinder 12 effects a rst adjustment of the metering of the fuel injector as will be described hereinafter.

A valve body 180 is sldably disposed within a central bore 182 in the pump housing 160 in close fitting relationship. A uid seal is effected between the valve body 180 and the central bore 182 of the pump housing 160 by a pair of O-rings 184 and 186 that are disposed in suitable circumferentially extending annular recesses 188` and 190 on the periphery of the valve body 180.

The valve body 180 has a central bore 192 therein that functions as a valve chamber 194. A bore 196 communicates with the valve chamber 194 and' with the upper end of the valve body 180. A check valve 198 is normally seated against a conical valve seat 200 that extends between the bore 192 and bore 196 in the valve body 180. The check valve 198 is biased against the seat 200 by a helical compression spring 202 that extends 'between the check valve 198 and an upper end face 201 of a metering screw 204. The metering screw 204 is threadably engaged in a threaded counterbore 206 in the valve body 180. A sealing washer 210 is biased against a transversely extending annular washer Aseat 212 at the upper end of the counterbore 206 by an upper end face 201 on the metering screw 204.

The metering screw 204 has a central `bore 214 that communicates with a bore 216 at the upper end of the metering screw 204 and with the valve chamber 194. The bore 216 functions as a fuel metering orifice between the chamber 194 and the Ibore 214, for a reason to be discussed hereinafter. A washer 220 is seated between the metering screw 204 and the end face 222 of the bore 182 to retain an O-rng 224.

'The pump housing 160 is closed, at the upper end portion 162 thereof, by an adapter 230 having a threaded central bore 232 therein for the acceptance of a conventional conduit locking screw 234. The locking screw 234 has a central bore 236 for the acceptance of a suitable fuel conduit 238 that is securely held within the adapter 230 by the locking screw 234. The adapter 230 has an annular recess 239 therein for the acceptance of a suitable sealng member 240, for example a conventional Caring. The sealing member 240 effects a fluid seal between the adapter 230 and the tubular side walls 162 of the pump housing 160.

The locking screw 234, adapter 230, pump body 180 and washer 220 are biased downwardly in the pump housing 160 -by a retainer plug 241 having an externally threaded portion 242 that is threadably engageable in the threaded lbore 166 in the pump holder 126. The retainer plug 241 has a pair of spaced parallel ats 244 and' 246 thereon to facilitate downward rotation thereof with respect to the pump holder 126, as by a conventional wrench, thereby to lock the aforementioned components against axial movement with respect to the pump housing and the pump with respect to the pump holder 126.

An upper end portion 250 of a tubular pintle shaft 252 extends into the bore 214 of the metering screw 204. A sliding seal is effected between 'the pintle shaft 252 and the pump housing 160 by the sealing ring 224. A central passage 255 in the pintle shaft 252 provides lfor the passage of fuel downwardly through the pintle shaft 252 from the bore 214 in the metering screw 204 as will be discussed. The pintle shaft 252 has a threaded lower end portion 256 that is engageable in a complementary internally threaded portion 257 in a tubular pintle body 260.

The pintle body 260 extends downwardly through a central bore 264 in the bight portion 70 of the plunger 60 in slidable engagement therewith. The pintle body 260 extends downwardly through the compression chamber 62 for the support of a pintle tip 270 that is threadably engaged with an internally threaded end portion 272 of the pintle 'body 260. The pintle tip 270 has a radially outwardly extending annular ange 274 thereon that is engageable with an annular lower end face 276 of the pintle -body 260 to position the pintle tip 270 axially with respect to the pintle body 260. A lower end face 278 of the annular flange 274 is of truncated downwardly convergent conical configuration of a predetermined area, for a reason to be discussed. The pintle tip 270 has a downwardly convergent conical end face 280 complementary to the conical seat 34 in the nozzle 30 so as to be engageable therewith in lluid sealing engagement. A spacer tube 290 extends centrally and longitudinally within the pintle body 260 and has a central passageway 292 therein to facilitate the passage of fuel downwardly from the central passageway 255 in the pintle shaft 252 into a cavity or fuel pre-chamber 294 within the pintle tip 270.

The pintle lbody 260 and therefore the end face 280 of the pintle tip 270 are biased Adownwardly with respect to the cylinder 12 and into the seat 34 in the nozzle 30 by a plurality of disk or Belleville washers 300 of truncated conical cross-sectional conguration that are stacked -with the radially inwardly convergent portions thereof in juxtaposed relation. The washers 300 extend between la lower end face 302 on the end wall 164 of the pump housing 160 and a transverse annular end face 306 on the pintle body 260 thereby biasing the end face 280 of the pintle tip 270 against its complementary seat 34 in the nozzle 30.

The pintle tip 270 has a plurality of downwardly divergent passageways 310 that communicate with the chamber 294 therein for the passage of fuel outwardly of the chamber 294 as will Abe discussed. The pintle body 260 has a transverse Ibore 312 that communicates with a transverse bore 314 in the pintle tip 270. The bore 314 communicates with a central bore 316 in the pintle tip 270. A longitudinally extending groove 320 on the outer periphery of the pintle body 260 communicates with the transverse bore 312 in the pintle body 260, and therefore the bore 314 in the pintle tip 270, at such times as a circumferential recess 322, that is spaced axially upwardly within the bore 264 of the plunger 60, is aligned with Ithe bore 312. The recess 322 is so positioned in the bore 264 that it provides communication between the transverse apertures 312 and 314 in the pintle body 260 and pintle tip 270, respectively, Aand the longitudinal groove 320 when the plunger 60 is in its lowermost position with respect to the cylinder i12.

Upon actuation of the fuel injector-igniter 10 of the present invention, as by moving the plunger 60 downwardly within the cylinder 12 by a suitable mechanism (not shown), a fresh charge of air within the compression chamber 62 is compressed therein upon passage of the plunger 60 past the inlet apertures 68 in the cylinder 12. As the plunger 60 moves downwardly with respect to the cylinder 12 air pressure within the compression chamber 62 builds up until, as the plunger 60 approaches the lower end of the cylinder 12, air pressure acting upon the annular surface 27S on the pintle tip 270 is sufficient to bias the pintle tip 270 and pintle body 260 upwardly against the bias of the stacked Belleville washers 300. At this time the compressed and heated air within the now relatively small compression chamber 62 passes downwardly past the radially outwardly extending passageway 310 in the pintle tip drawing fuel outwardly of the fuel pre-chamber 294 therein and into the venturi defined by the radially downwardly convergent seat 34, passageway 36 and radially downwardly divergent nozzle 38. Simul taneously, the fuel charge disposed in the fuel pre-Chamfber 294 of the pintle tip 270 is subjected to an increased pressure by air passing inwardly of the pintle tip 270 through the longitudinal passageway 320, annular recess 322, and the apertures 312 and 314 in the pintle body 260 and pintle tip 270, respectively. It will be noted that at this time a pressure differential exists between the fuel pre-chamber 294 and the orifice 36 which pressure differential operates to force the fuel outwardly at a high velocity.

Because air within the compression chamber 62 is compressed well above 1000 p.s.i. and thereby to raise its temperature well above the ignition point of the fuel charge contained within the chamber 294, the fuel is ignited upon passage thereof outwardly of the downwardly divergent passageways 310 and within the orifice 36 of the nozzle 30. The relatively lower pressure within the orifice 36 draws Vthe fluid downwardly and outwardly of the chamber 294 where it is atomized and ignited by the compressed air passing between the conical surface 280 on the pintle tip 270 and the conical seat 34 on the nozzle 30.

Upward movement of the plunger 60 under the bias of the operating spring 100, upon release of 'the downward bias thereon by a cam or other suitable mechanism (not shown), effects a partial vacuum within the compression chamber 62 which extends into the valve chamber 194. Because a constant fuel pressure is maintained within the conduit 238, as by a fuel pump (not shown), the fuel inlet valve 198 is biased downwardly against the spring 202` when a predetermined pressure differential on opposite sides of the valve 198 is reached. The fuel flows downwardly through the fuel inlet chamber 194 due `to the aforementioned pressure differential and through the aperture 216 in the metering plug 204. Because the aperture 216 functions as an orifice the flow of fuel between the chamber 194 and the bore 214 is throttled, the amount of fuel passing the orifice 216 being dependent upon the time required for the plunger to move from its lowermost position after injection of ignited fuel through the nozzle 30 to the point where the apertures 68 in the cylinder 12 are open thereby breaking the partial vacuum within the compression chamber 62 and reducing the pressure differential on opposite sides of the fuel inlet valve 198 to permit Closure of the valve 19S. Therefore, the amount of fuel injected upon each stroke of the plunger 60 is determined by the fuel pressure in the line 23S as related to the size of the orifice `216 and the speed of return of the plunger 60 from the injection position to the venting of the compression chamber upon opening of the apertures 68.

A modified fuel metering system is shown in FIGURE disposed within the pump housing 160 discussed hereinbefore. The upper end portion 250 of the pintle shaft 252 is associated with the pump housing 160 and sealing washer 253 in the manner discussed hereinbefore. A pump body 402 is disposed within the interior bore 182 of the pump housing 160. The pump body 402 has an upper annular recess 404 for the acceptance of an upper sealing washer 406, for example, an O-ring, to effect a uid seal between the pump body 402 and pump housin 160.

gl`he pump body 402 has a longitudinally extending bore 410 that is offset from the central longitudinal axis of pump body 402 and communicates with -a longitudinally extending bore 412 that defines a shuttle chamber 414. The bore 412 communicates with the bore 414i through a passageway 416 at the upper end of the bore 412. A frusto-conical valve seat 418 extends between the bores 412 and 416 for the seating of a shuttle 420. The shuttle 420 has a frusto-conical upper end portion 422 complementary to the valve seat 418 to effect a fluid sealing seat therebetween.

A lower end plug 430 for the pump body 402 is disposed in a recess 432 in the lower end of the pump body 402. The end plug 430 has an upper end portion 434 that extends into an offset bore 436 in the recess 432 of the pump body 402. The upper end portion 434 of the end plug 430 has a central passageway 438 therein that communicates with the bore 412 and therefore the shuttle chamber 414 in the pump body 402. The upper end portion 434 of the end plug 430 has a frusto-conical valve seat 440 complementary to a frusto-conical seating surface 442 on the shuttle 420 so as to effect a fluid sealing seat between the shuttle 420 and the end plug 430 when the shuttle 420 is in its lowermost position.

A passageway 450 extends radially outwardly from a central bore 452 in the end plug 430` for communication with the passageway 43S in the upper end portion 434 of the end plug 430. The upper end portion 250 of the pintle shaft 252 is slidably disposed in the central bore 452 of the end plug 430. A suitable sealer washer 453 effects a fluid seal between the end plug 430 and the housing 160.

The pump body 402 has a threaded transverse bore 460 for the acceptance of a suitably threaded diaphragm retainer 462. The diaphragm retainer screw 462 has `a central bore 464 for the acceptancel of a metering piston 466 that is slidable therein transversely of the pump body 402. A metering valve spring 468 normally biases the piston 466 to an index position defined by an end wall 470 of the bore 460. A diaphragm 472, preferably of, for example, silicone rubber, extends across the end wall 470 of the bore 460 and is held, at its outer periphery, against a diaphragm seat 474 by an end face 476 on the diaphragm retainer screw 462. A bore 480 communicates with the shuttle chamber 414 and with the diaphragrn 472 thereby to define a fuel metering chamber 481.

An adaptor 486 closes the pump housing 160 and has an annular recess 488 therein for the acceptance of a seal 490, for example an O-ring, to effect `a fiuid seal between the adaptor 486 and the pump housing 160. The end plug 486 has a threaded central bore 489 for the acceptance of a conventional conduit locking screw 490i that has a central bore 492 therein for the acceptance of a uid conduit 494. The locking screw 490 holds the conduit 494 in fluid sealing relationship with respect to the upper end plug 486 in the conventional manner. A lower end portion 496 of the conduit 494 extends into a chamfered counterbore 498 in the adaptor 486 thereby to be in fluid communicating relationship with the longitudinal bore 410 in the pump body 402.

-Upward movement of the plunger 60 under the bias of the operating spring reduces the pressure in the compression chamber 62. This lowered pressure extends through the apertures 312 and 314 in the pintle body 260 and pintle tip 27 0, respectively, and upwardly through the central passage 255 in the pintle shaft 252, permitting the piston 466 to bias the diaphragm 472 to the left to push fuel outwardly of the metering chamber 481 and downwardly into the fuel pre-chamber 294 in the pintle tip 270, the metering chamber 481 having been filled and the piston biased to the retracted position on the compression stroke of the plunger 60, as will be described. At such time as the pressure differential on opposite sides of the shuttle increases suliciently to effect downward movement of the shuttle 420 due to fuel pressure in the conduit 494, the flow of fuel outwardly of the metering chamber is terminated. Fuel then flows into the metering chamber-481 and the piston 466 is moved to the right, as seen in the drawings, an amount related directly to the upstream pressure of the fuel. Therefore, the volume of the chamber 481 and, accordingly, the quantity of fuel contained therein is directly related to the upstream pressure of the fuel.

As the plunger 160 commences a downward stroke under the influence of suitable mechanism (not shown) increased pressure in the compression chamber 62, acting through the passages 312, 314 and 255, biases the shuttle 420 upwardly against the seat 418 in the valve body 402. The increased pressure then biases the piston 466 to the right completely compressing the spring 468 and thereby preparing the piston 466 for the next fuel ejection stroke upon release of the pressure. Upon release of the pressure effective on the piston 466, fuel within the metering chamber 481 is pumped downwardly through the passages 438, 456 and 255 into the fuel pre-chamber 294 in the pintle head 270, as discussed hereinbefore. Therefore, on each complete cycle of the plunger 160 a new charge of fuel is first metered in the metering chamber 481 and then deposited in the fuel pre-chamber 2.94, the quantity thereof being directly related to fuel pressure in the conduit 494. This novel valving structure permits positive control of the energy input of the fuel injectorigniter to an internal combustion engine by simply controlling Huid pressure at a point upstream from the injector-igniter 10.

It is to be noted that the combustion system of the present invention effects supercompression of air only as opposed to the compression of an air-fuel mixture heretofore known in the art. Further the supercompressed air is employed to pick up the fuel charge and carry it into the combustion chamber. The use of a convergentdivergent venturi aids in drawing the fuel into proximity with the supercompressed air and in admixing the charges due to relatively high turbulence within the high velocitylow pressure are-a of the venturi. A means is provided that, in combination with the venturi, effects a pressure differential on opposite sides of the fuel charge.

Further, the use of a reciprocable pintle as a differential area valve results in the injection of the entire portion of supercompressed air and fuel into the working cylinder, precluding entrapment thereof.

Another feature of the present invention is the angular relationship between the supercompressed air passages and the fuel passages that results in relatively eicient admixing of the air and fuel.

From the foregoing description, it is apparent that the combustion system of the present invention, which provides for the simultaneous injection and ignition of a fuel into a combustion chamber of an internal combustion engine, reduces the deleterious effects of ignition lag and offers material advantages in terms of combustion, expansion, and thermal efficiencies. The problems heretofore attendant with the ignition of relatively lean mixtures and operation at low load conditions are substantially eliminated.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What Vis claimed is:

1. A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-gniter comprising a supercompression chamber, means for supporting a liquid fuel charge internally of said supercompression chamber, means reciprocable within said supercompression chamber for compressing a relatively small volume of air in isolated relationship with respect to the expansion chamber to a predetermined pressure having a temperature sufficient to ignite said fuel, and means for admixing said supercompressed air and said fuel to ignite and inject said fuel into the expansion chamber upon the occurrence of said predetermined fluid pressure comprising a venturi normally closed by said fuel supporting means and openable on the occurrance of said predetermined pressure in said supercompression chamber, and a plurality of radially spaced passage means in said fuel supporting means communicating with the convergent section of said venturi and with said fuel charge whereby upon opening of said venturi the liow of fuel from said passage means, respectively, converges at the constricted portion of said venturi to effect maximum impact atomization and ignition of said fuel.

2. A fuel injector-igniter for an internal combustion engine having an expansion chamber comprising means for metering a charge of fuel including a metering charnber having a fuel inlet and a fuel outlet, a shuttle valve within said metering chamber and operable to close said inlet or outlet aperture, selectively, and means for operating the shuttle valve in response to av predetermined pressure condition to control fuel ow, means for isolating said fuel charge from the expansion chamber, a supercompression chamber, means for compressing a fluid in said supercompression chamber in isolated relationship with respect to the expansion chamber to a pressure having a temperature sutiicient to ignite said fuel, means for admixing said fluid and said fuel thereby to ignite said fuel, and means for injecting said liuid and ignited fuel mixture into the expansion chamber.

3. An injector-igniter in accordance with claim 2 wherein the metering chamber has a variable volume.

4. A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-igniter comprising a cylinder, a plunger reciprocable within said cylinder for compressing a fluid, means within said plunger for metering a charge of fuel, means for isolating said fuel charge from the expansion chamber, means on said plunger for conducting a charge of fuel between said metering means and said isolating means, means responsive to a predetermined pressure for admixing said fluid and said fuel thereby to ignite said fuel, and means for injecting said uid and ignited fuel mixture into the expansion chamber.

References Cited inthe file of this patent UNITED STATES PATENTS 1,329,797 Raabe Feb. 3, 1920 1,501,884 Short et al. July 15, 1924 1,896,174 Honn Feb. 7, 1933 2,033,155 Scott Mar. 10, 1936 2,091,987 Honn Sept. 7, 1937 FOREIGN PATENTS 469,107 France May ll, 1914

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