US2700342A - Fuel pump - Google Patents

Description

Jan. 25, 1955 o. FRENCH y 2,700,342

FUEL PUMP Filed May 22, 1953 United 5ms Passt- 0 FUEL PUMP Louis 0. French,y Milwaukee, Wis.

Application May 22, 1953, Serial No. 356,805

13 Claims.. (Cl. 10S- 41) The invention relates to fuel injection pumps for internal combustion engines.

In fuel pumps in which metering. of the fuel charge is controlled by a sleeve valve cooperating with a fuel vspill or discharge port in thev pump plunger, the valve having a close lit with a part of said plunger surrounding said port, I find that the plunger as it moves onA its pumping stroke tries to carry the valve with it', and this has= tobe opposed by the valve actuator. Furthermore there is always some leakage from a metering sleeve valve, the leakage being greater atA light loads` since the metering path is shorter. One object of the present invention is to provide a metering means byV which the forces induced bythe movement of the plunger upon the metering control are minimized, andv also the spill or discharge porti is positively sealed against leakage except when by-pass'ing of a portion of the fuel charge is desired. Moreparticularly, the present invention provides alvalve held closed by fuel at pump pressure during the Working stroke of the-pump and controlling the spill' or discharge port on the plunger and' adjustably positionabl'e means free of the plunger and engageable with the valve sooner o'r later in the stroke of the plunger to open said'fval've to'by-pass more or less of the fuel charge.

This application is a continuation in' part` of my application Serial No. 350,415, tiled' April 22, 1953, for Fuel Pump, now abandoned, as to claims for common subject matter, and in this connection a further object' of the invention is to provide a compression pressure operated fuel injector in which the pump chamber is usedas a pressure accumulator chamber and in which that portion of the/fuel pump plunger which' worksin the purnpycham-v ber has full diameter sealing area for thelength of its stroke and the meteringof thecharge is accomplished ut side of the pump chamber, anda timing valve controls the flow of' fuel from the pumpchamber.

A further objecty of the invention is to provide an arrangement of pump parts which permits a portionof the fuel discharge passage communicating with the upper or outer end of theA pump chamber acting as a fuel inlet passage for said chamber.

' A further object ofthe invention is to provide an aux* iliary hydraulic cushioning means between the operating piston and the housing to stop the outward movement of said piston.

The invention further consists in the several features hereinafter set forth and more particularly' definedl by claims at the lconclusion hereof.

In the drawings: Fig. l is a vertical sectional view throughs' fuel pump embodying the invention; Fig. 2 is a detailedr horizontal sectional view taken on the` line 2-2 of Fig. 1'; l Fig. 3 is a detailed horizontal sectional View takenlon the line 3 3 with the crank in mid-position;` Fig. 4, is a detailed verticalv sectional view showing a modified form of spill valve;

Fig. 5 is a vertical sectionalview similar to Fig..1 show.- ing certain modifications, parts being broken away. g n Referring to the. drawings, thepumpincludes a housing formed' of parts 5a and 5b .having differentialdiameter bores 6v and .7 in which the operating piston S.- works. Part 5a has the pump bo`re.6l extending lengthwise through its central portionv and. has-a tubularprojection 9, counterbores 10 and 11 fuel passages 12: and 12a, .ai discharge port 13, a valve bore 14` connectingv port 413 on its pumping stroke.

2,700,342 Patented an. 25., 1955 ice withl an angled discharge passage 15` communicating with bore 6 below the pump chamber P. v

Part 5bv has" the central bore?A alined withbore 6', apassage 116, a bore 1-7, anv annular groove 18, anda re, ducedlower end upon which apiston stop and nozzle cap 19 is mounted. Projection 9 has a centering tit in bore 7` andA with a yieldable sealing ring 20 is clamped to the upper end of 5b by screws21 indicated in Fig. 3".v

Counterbore 1-0 has a threaded upper end to receive the housing 22 ofl a priming valve 23 controllingV al relief passage A24 at the upper end. of chamber P, said valve being normally closed by a manually operated screw 25.

The operating piston 8 includes a pump. plungerA 26 and ahead 27 provided with a ring seal 28, said head having a threaded bore-29 to engage a nut 30` that holds the ring seal in position and also forms with the heada housing for a discharge valve housing 31 that is provided with a discharge tube extension 32 workingin aA bore 33 in the cap 19; and supplying an enlargement 34 thereof thatcomrnunicateswith spray orifices 35 in said cap to form a spray nozzle. A dischargeI check valve 36 and its closingl springl 36a is mounted in housing 31 and conf trolspassage of fuel through a discharge passage '37 in the plunger that communicates by a cross bore with an annular groove 3S spaced at least a pump strokeis length from the inner end of the plunger and which groove'rregistersduring the pistons movementk with thepassage 15 which it laps at the end of thestroke to tr-apfuel` in chamber P and. the passages leadingv from said chamber to said groove. Plunger 19 also has aY spilly or discharge port 39 connecting with passage 37 between groovev 38 and valve 36. Piston S is movedy to'V filling position in which nut 30 rests in the bottom of a counter bore 40 in cap 19 by a spring 41 which is seated at its upper end on a ring 42 abutting a retainer ring 43 engaging in` groove 18.

The discharge port- 39 is closed by a valve which may be a ball valve 44.(Fig. 1) oraninwardly opening needle valve 44a (Fig. 4), said valve being normally closed by a spring 45 interposed between the valvev and a screw plug 4d in said plunger. The front end of the valve 44- or 44a is designed to stick out a short distance beyond the outer wall of the'plunger so that this end may be engaged by an adjustably positionablewedge and opening member 47 as the piston 8 moves outwardly ofthe engine cylinder The valve 44a has grooves or flats 44b for-ming fuel passages. Member 47 may take various forms but, to obviate keying of the plunger, this member is preferably in the form of a sleeve mounted to slide on the walls of bore 7 and having a bevelled orA inclihed lower edge 48. Positioningv of sleeve l47 relative to the valve 44 or 44a is effected by an actuator having an exterior disposed operating connection and includes a control shaft 49 having an exteriorly disposed arm 5.0

under manual or governor controler both and an eccentrically disposed crank pin 51 at its; inner end engaging in a slot 52 in sleeve 47 and extending normal to: the axis thereof. The reduced diameter portion of shaft 49 is rotatably mountedy in a bushing 53 and provided with a rubber O-ring seal 54, and its head is held against a seat on the bushing by a spring washer 49a. Bushing 53 is secured in housing 5b and has a close fit in bore 17 and an O-ring seal 53a.

Passage of fuel from the port 13 to passage 15 is con'- trolled by a timing valve which may be a crank shafty timed and operated piston valve? 55 or a compression pressure timed and operated needle valve 55a., Valve 55 is slidably mounted in bore 14 and urged to closed position by a spring 57 and moved vto open position by an engine timed and operated 1ever 58 by any suitable valve gear. Valve 55 has an annular groove 59 adapted to I i be-moved into register with port 13, and passage 15 to connect pump chamber P with groove 38. Valve 55a is slidably mounted in a housing 60 and urged to closed position by a spring 61 interposed between said valve and a nut 62 having an adjustably threaded connection with housing 60. This valve connects port 13 with passage 14 and is opened when the fuel pressure in chamber P reaches a value sufficient to overcome the' loading of spring 61 to permit fuel to pass from 'port 13 to 'passage 15.

The pump is suitably mounted and clamped in the engine head 63 against a gasket 64, there being a cooling jacket 65 surrounding the lower end of housing 5b.

'lne parts of piston 8 cooperate with bore 7 to form a chamber 66 inwhich fuel under suitable supply pressure is continuously circulated by any suitable supply system (not shown) which may include a pump, tank, piping and preferably a cooler. The fuel may come in by way of passage 12 or passage 16 and leave by the other passage.

The lower end of the bore 6 has the counterbore 11 that cooperates with a part 67 of the plunger as the piston 8 completes its stroke to form a cushioning dashpot which thereby increases the effective stop area over that of the area of the plunger that works in the pump chamber P as the groove 325 laps the passage 15.

With the parts of the pump as shown in Fig. l as the engine piston makes its compression stroke and the compression pressure builds up in the combustion chamber C, this pressure is transmitted through holes 68 and a space 69 in cap 19 to the lower end of piston 8 and by it to the fuel in chamber P so that near the end of the compression stroke the pressure in this chamber is three to four times or more as great as the compression pressure depending upon the ratio of the diameters of the piston head and pump plunger. At the desired time in the engines cycle, which may with an engine timed valve 55 be thirty to five degrees before top dead center on the compression stroke of the engine or which with the compression timed valve 55a be within the crank angle range above given or less, the timing valve is opened, and fuel then passes through port 13 past the timing valve 55 or 55a, discharge passage 15, groove 38, passage 37, past check valve 36 through extension 32, orifices 35 and into combustion chamber C. Depending upon the setting of sleeve 47, sooner or later as piston t moves upwardly, the valve 44 or 44a contacts the edge 4S which acts to push valve 44 or 44a inwardly to an open position to by-pass more or less fuel from the discharge line and cause the valve 36 to close, it being noted that the fuel supply pressure in chamber 66 is not, during injection, sucient to overcome the loading then imposed on valve 44 or 44a. As the piston 8 continues to move relative to the sleeve 47, the exposed tip of valve 44 or 44a moves along the inner bore of said sleeve holding said valve in open position during the remainder of the stroke of said piston. When on the upward movement of piston 8 the lower edge of groove 38 laps the passage and the part 67 enters counterbore 11, the movement of said piston is stopped by the trapping of fuel in pump chamber P and counterbore 11. The piston stays in its upper position during the high pressure period of the engines cycle following injection, and until the pressure of the gases in chamber C drop to a value permitting spring 41 to return the piston to4 its initial position.- It is to be noted that while the opening of valve 44. or 44a produces a drop in pressure in the discharge line from the pump which permits valve 36 to close, that this does not necessarily permit timing valve 55a, if used, to close as this valve will hold open so long asthe pressures in cham-ber P are suflicient to overcome the loading of spring 61.

Valve 55 is held open until sometime during the induction stroke of a four cycle or the scavenging period of a two cycle engine the engine valve gear permits spring 57 to close it. When valve 55 is used, the spring 45 may be a light spring to permit the fuel pressure in chamber 66 to hold valve 44 or 44a open after it leaves the sleeve 47, and it will, of course, be open so long as it engages the sleeve, and since on the downward stroke of the piston valve 5S is open, the valve 44 or 44a will act as an inlet valve to allow fuel at pump supply pressure to pass upwardly through parts of the fuel discharge line including port 13 into the upper end of the pump chamber to ll this chamber assisted at the end ofthe stroke by the uncovering of inlet passage 12 by plunger 26, it being noted that the loading discharge check valve spring 36a is greater than the fuel supply pressure. Thus any tendency for forming a vacuumv in chamber P before port 12 is uncovered is prevented, and the use of a separate spring closed inlet valve for the'pump chamber P is obviated. ln some instances the port 12 leading to the -pump chamber P may be dispensed withv where the valve 44 or 44a is used as a fuel inlet valve. In fno delivery position of the sleeve 47 the valve 44l or '44a is held open thereby during the entire stroke of the piston, so that all the fuel charge will be by-passed through the port 39. It will be obvious to one skilled in the art that since pressure in the pump chamber during the pumping stroke builds up rapidly to a greater pressure than that existing in chamber 66, that this pressure constitutes a uid pressure means which acts to close and hold the valve 44 or 44a to its seat so that the spring 45 can be disposed with. Also where no timing valve such as valve 5S is used, the passage 37 can lead directly to pump chamber P through the upper end of plunger 8.

The edge 48 may have a forty-tive to thirty degree angle relative to the vertical axis of the sleeve so that the force of impact of valve 44 or 44a may be resolved into a component normal to the axis of the sleeve and an axial component of equal or less value with the result that except for a very brief interval required to cam or wedge said valve to its open position, only a small force is required to hold the sleeve 47 in its adjusted position, and as soon as the tip of the valve rides on the inner bore of the sleeve 47, then the small forces exerted by the open valve against the sleeve are normal to the sleeve, and therefore, tend to hold the sleeve in its adjusted position, it being noted that the frictional forces between the tip of the valve and the sleeve are small and that as soon as the valve opens, only the loading of the spring 45 has to be overcome. As a result, if the sleeve 47 is governor controlled, the only time that it might not be instantly responsive to governor control is during the extremely brief interval to move the valve 44 or 44a to its open position, it being noted that the valve only needs to be moved a few thousandths of an inch, for example, .003 to .005 inch, to its full open position. It is also to be noted that the inner bore of sleeve 47 is spaced a sufficient distance from that part of the plunger carrying valve 44 or 44a that there is clearance between these' parts in the open position of the valve. Also, as valve 44 or 44a is a positively seated valve, there will be no leakage losses during fuel injection while the valve is closed.

It is also to be noted that the spill valve shown herein can be easily tested for leakage by separating the housing parts and filling the pump chamber with fuel and then inserting the pump plunger and putting pressure on the fuel. If under these conditions the valve 44 seals properly, all fuel will go out through the holes in the extension 32.

I desire it to be understood that this invention is not to be limited to any particular form or arrangement of parts except in so far as such limitations are included in the claims.

What I claim as my invention is:

1. In a fluid pressure operated fuel pump, the cornbination of a housing having a pump chamber, means for supplying fuel to said chamber, a fluid pressure operated operating piston having -a pump plunger working in said chamber, a discharge passage from said pump chamber to an outlet, a timing valve controlling said discharge passage `and permitting a build up of fuel pressure in said chamber by the uid pressure acting on said piston, said discharge passage including a discharge conduit in said plunger having a spill port, a valve seat in said port, valve mounted in said piston and controlling said port and having a part projecting outwardly beyond said port, fuel pressure means generated by pressures built up in said pump chamber and conduit during the discharge stroke of said plunger for holding said valve closed against its seat, and variably positionable means mounted in said housing and engageable with said projecting part of said valve as said piston moves on its pumping stroke to open said valve to by-pass more or less fuel discharged from said pump chamber.

2. The fuel pump as defined in claim 1, wherein the variably positionable means mounted in said housing includes a sleeve adjustable lengthwise of said piston and provided with a bevelled edge engageable with the said projecting part of said valve to open said valve.

3. In a uid pressure operated fuel pump, the combination of a housing having concentric bores of differential diameters including a pump bore, a counterbore and a larger bore, a fluid pressure actuated operating piston having a head working in said larger bore and a pump plunger working in said pump bore and having a part movable into said counterbore as the piston nears the end of its pumping stroke to trap fuel in said bore to arrest the movement of said piston, a pump chamber in said pump bore, means for supplying said pump chamber with fuel, a discharge passage from said pump chamber to an outlet, a timing valve controlling said discharge passage and permitting a build up of fuel pressure in said pump chamber by the fluid pressure acting on said piston, said discharge passage including a part lapped by said plunger as the piston nears the end of pumping stroke to trap fuel in said pump chamber to further arrest the movement of said piston, and metering means in said discharge passage between said timing valve and said outlet for by-passing more or less fuel discharged from said pump chamber.

4. In a fluid pressure operated fuel pump, the combination of a housing having a pump chamber, a fluid pressure operated operating piston having a pump plunger working in said pump chamber, a discharge passage from the outer end of said pump chamber to an outlet, a timing valve controlling said discharge passage and permitting a build up of fuel pressure in said chamber by the lluid pressure acting on said piston and adapted to remain open during the return stroke of said piston, said discharge passage including a discharge conduit in said plunger having a by-pass port, fuel pressure closed bypass valve mounted in said piston and controlling said port and having a part projecting outwardly beyond said port, said housing having a fuel supply chamber into which said by-pass port discharges, said by-pass valve also adapted to function as a fuel inlet valve to supply fuel to said pump chamber while said timing valve is in its open position, and variably positionable means mounted in said housing and engageable with said projecting part of said by-pass valve as said piston moves on its pump stroke to open said valve to by-pass more or less fuel discharged from said pump chamber.

5. In a fluid pressure operated fuel pump, the combination of a housing having a pump chamber, a fluid pressure operated operating piston having a pump plunger working in said chamber, a discharge passage from the outer end of said pump chamber to an outlet, a timing valve controlling said discharge passage and permitting a build up of fuel pressure in said chamber by fluid pressure acting on said piston and adapted to remain open during the return stroke of said piston, a by-pass valve in said discharge passage beyond said timing valve and also acting as a fuel inlet valve for said pump chamber, and means acting to open said by-pass valve as said piston moves on its pumping stroke to by-pass more or less fuel from said pump chamber.

6. In a fuel pump, the combination of a housing provided with a pump chamber, a plunger working in said chamber, a passage in said plunger having a spill port, a valve seat in said port, a valve engageable with said seat in said spill port to control said port, means within said passage to hold said valve on said seat in valve closing position, and variably positionable means mounted in said housing and contactible with said valve to open the same as said plunger moves on its pumping stroke.

7. The fuel pump as defined in claim 6 wherein the variable positionable means mounted in said housing includes a sleeve adjustable lengthwise of the plunger and provided with an edge contactible with said valve with a wedging action to open said valve.

8. The fuel pump as defined in claim 6 wherein the spill port discharges into a second chamber having fuel under pump supply pressure and means in said port permits said valve to act as an inlet valve for said passage when the pressure in said second chamber exceeds that tending to hold said valve seated.

9. In a fluid pressure operated fuel pump, the combination of a housing having a pump chamber, means for supplying fuel to said chamber, a fluid pressure actuated operating piston having a pump plunger working in said chamber, a discharge passage from said pump chamber to an outlet, timing means in said discharge passage operative to trap fuel in said pump chamber to build up its pressure until released to said discharge passage, and

metering means in said discharge passage upstream of said outlet for by-passing fuel discharged from said pump chamber.

l0. In a fluid pressure operated fuel pump, the combination of a housing having a pump chamber, means for supplying fuel to said chamber, a fluid pressure actuated operating piston having a pump plunger working in said chamber, a discharge passage from said pump chamber to an outlet, a timing valve controlling said discharge passage and permitting a build up of fuel pressure in said chamber by the fluid pressure acting on said piston, and metering means in said discharge passage between said valve and said outlet for by-passing fuel discharged from said pump chamber.

ll. In a fluid pressure operated fuel pump, the combination of a housing having a pump chamber, means for supplying fuel to said chamber, a fluid pressure actuated operating piston having a pump plunger working in said chamber and having a full diameter sealing contact with the walls of said chamber for at least a strokes length of said piston, a discharge passage from said pump chamber to an outlet, a timing valve controlling said discharge passage and permitting a build up of fuel pressure in said pump lchamber by the fluid pressure acting on said piston, and metering means in said discharge passage between said valve and said outlet for by-passing fuel discharged from said pump chamber.

l2. In a fluid pressure operated fuel pump, the combination of a housing having differential diameter bores, a fluid pressure actuated operating piston having a head working in the larger of said bores and a pump plunger working in the smaller of said bores, a pump chamber in said smaller bore, means for supplying said pump chamber with fuel, a discharge passage having a section formed in said housing extending from the outer end of said pump chamber to the smaller bore at a point at least a strokes length distance from that end of said plunger that works in said smaller bore and a section formed in said plunger, said last named discharge section including an annular groove in register with the discharge section in said housing for a pump length stroke but which on further movement of said plunger moves to a lapped p0- sition relative to said first named section to trap fuel in said first named section and pump -chamber to stop the movement of said piston, the discharge section also including a spill port intermediate its ends and below said annular groove, a metering valve cooperating with said spill port to control the by-passing of fuel from said discharge passage, and a timing valve in the discharge section formed in the housing controlling the beginning of the pumping stroke and acting to trap fuel in said pump chamber under pressures built up therein by fluid pressure acting on said head. v

13. In a fluid pressure operated fuel pump, the cornbination of a housing having differential diameter bores, a fluid pressure actuated operating piston having a head working in the larger of said bores and a pump plunger working in the smaller ofsaid bores, a pump chamber in said smaller bore, means for supplying said pump chamber With fuel, a discharge port for said chamber, interconnectible discharge passages in said housing and plunger connecting said port with a pump discharge outlet, a timing valve controlling the discharge of fuel from said port through said passages and controlling the beginning of the pumping stroke and acting to trap fuel in said pump chamber under pressure built up therein by fluid pressure acting on said head, and fuel metering means including Ia by-pass port in said plunger disposed in the discharge passage in said plunger above said outlet and below the connection vbetween the discharge passage in the housing with the discharge passage in said plunger.

Evans Nov. 3, 1953 French Dec. 15, 1953

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