US3338168A

US3338168A - Fuel injection pump

Info

Publication number: US3338168A
Authority: US
Inventors: Charles W Davis
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1964-01-23
Filing date: 1964-01-23
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29

Description

Aug. 29, 1967 c. w. DAVIS FUEL INJECTION PUMP 2 Sheets-Sham 1 Filed' Jan. 23, 1964 Haw M T f v, M u. Z i

C. W. DAVIS Aug. 29, 1967 FUEL INJECTION PUMP 2 Sheets-Sheet 2 Filed Jan. 25, 1964 [nde/r perfor/5 United States Patent Oiilice 3,338,168 Patented Aug. 29, V1967 3,338,168 FUEL INJECTION PUMP Charles W. Davis, Fishkill, N.Y., assignor to Texaco Inc., New York, N.Y., a corporation of Delaware Filed Jan. 23, 1964, Ser. No. 339,720 17 Claims. (Cl. 103-2) This invention relates generally to a fuel injection system in an internal combustion engine, and specifically, to a fuel injection pum-p of the single plunger distributor type.

Single plunger or single pumping element distributor type pumps can be classified broadly according to the methods used to control the quantity of fuel injected. These include cut-olf control wherein a portion of the constant amount of fuel displaced by the plunger is dumped back to the supply side of the pump, depending on the amount required by the engine. Cut-off control involves short leakage paths and therefore very close and expensive fits to control leakage. Erosion caused by the sudden release of high pressure fuel is also a problem. y

Another control means involves the throttling of the supply of fuel to the pumping element. This results in the creation of low pressures in the pumping element and introduces the problem of fuel ashing into vapor, with resulting deterioration of injection characteristics, if the fuel is sufficiently Volatile, and particularly if the fuel becomes heated. Advantages of the throttled intake pump include long leakage paths with less critical lit of parts and so a cheaper construction.

A third method for control of injection quantity is positive regulation of the `stroke of the pump plunger. With this control arrangement, it is possible to obtain most of the advantages of the throttled inlet arrangement while avoiding the -fuel vaporization problems that are inherent with inlet throttling control.

Accordingly, it is an object of the present invention to provide a new land improved fuel injection pump of the single plunger distributor type to prevent flash vaporization of fuel into va-por.

It is another object of the invention to provide a single plunger distributor fuel injection pump wherein the quantity of fuel injected is regulated by control of pump plunger travel.

Still another object of the invention is to prevent flashing of fuel in a single plunger distributor type fuel injection pump having plunger travel control and unrestricted filling.

Another object of the invention is to provide a novel fuel injection pump of the single plunger distributor type having the quantity of fuel injection regulated by cont-rol of pump plunger travel, and with unrestricted filling and check valves to prevent back flow of fuel from pressurized delivery lines.

These and other objects, features and advantages of theinvention will appear from a reading of the specication, detailing a description of the structure illustrated in the accompanying drawings, wherein FIG. 1 is a diagrammatic longitudinal section view of the improved Vfuel injection pump;

FIG. 2 is an axial view taken along 2-2 of FIG. l;

FIG. 2a is a sectional view taken along line c-c of FIG. 2.

FIGS. 3a and 3b are cross-sectional views taken respectively along lines a-a and b-b of FIG. 1;

FIG. 4 is a polar timing diagram; and

FIGS. 5 and 5a respectively, are longitudinal and axial section views of a modification of the cam control means for maximum fuel quantity.

In accordance with my invention, positive mechanized control of plunger travel in the pump regulates the quantity of fuel to be injected, and provides for easy adjustment of maximum fuel output during operation whereby the proper weight of fuel -delivered per injection can .be maintained with fuels having different specific gravities and under variable intake air densities.

As disclosed in the gures of the drawings, the fuel injection pump is for a four cylinder engine and includes a rotor 1 rotatably mounted in housing 2 and driven by the engine through drive sha-ft 3. The housing is shown as containing an inlet passage 4 to which fuel is supplied under low pressure by a 'transfer pump (not shown). Inlet passage 4 indexes with inlet passages 5 in the rotor as the rotor turns. The housing also contains a discharge passage 6 for each cylinder of the engine, which index with a single discharge passage 7 in the rotor. Rotor passages 5 and 7 are interconnected by an axial rotor passage 8 which also interconnects with a diametral bore or chamber 9 through the rotor and in which opposed plungers 10 are slidably mounted, free to move in and out in a radial direction. Thus, the space between the inside ends of the plungers forms a p-ump chamber. A check valve 11 is located in passage 8 between passages 5 and 7 to prevent back flow of pressurized fuel. Cam roller follower shoes 12 holding cam rollers 13 as followerroller assemblies are mounted in guide slots in the rotor at the ends of the plunge-r bore. The follower-roller assembly is free to move in a radial direction and prevented from moving axially by the housing on one side and by retainer ring 35 on the opposite side. The housing and rotor are mounted in case 14 which also holds cam ring 15 mounted stationary therein. The cam ring has as many internal cam lobes 16 as there are cylinders in the engine. Each cam lobe is fitted with a movable ramp which v is pinned to the ca-m ring by pivot pins 17. The ramps consist of two side rails 18 which straddle the cam ring and are joined together by cross bar 19. A linger 20 with conical adjusting nut 21 protrudes from one side rail of each ramp, the axial position of the nut on the finger providing an adjustment of overall finger length. The ramps pivot or rotate about the pivot pins 17, their extreme outward position `being limited by each cross bar striking the case and housing as at points A, the ramp position illustrated in FIGS. 1 and 2, and their extreme inward position being limited by each cross lbar striking the cam ring, as at point B, FIG. 1.

The inner edges of the ramp rails and the internal surface of the cam ring form a cam surface, with that portion of the cam surface formed by the ramp rails being adjustable, depending on the positioning of the ramps. The ends of the cam rollers overlap the inner edges of the ramp rails and during rotation of the rotor, the radial movement of the cam rollers, roller followers and plung-l ers is governed by this cam surface. When the ramps are held in their innermost position, the rails bridge the circumferential distances between the cam lobes thereby forming a cylindrical cam surface which holds the rollerfollower assemblies and plungers in their innermost position as the rotor turns. No plunger motions result and so no fuel is pumped. When the ramps are positioned at any point other than their innermost position, the rollerfollower assemblies and plungers move radially outward along the ramp rails until the rollers strike the cam ring, permitting a charge of fuel to enter the pump chamber via passages 4, 5 and 8. As rotation continues, the rollers engage the cam lobes and are forced inward along With the roller followers and plungers, causing fuel t0 be pumped from the pump chamber to a cylinder of the engine via passages 8, 7 and 6, and the external piping and injection nozzle (not shown), the amount of fuel delivered being dependent on how far the position of the ramps permitted the plungers to move radially outward.

The inlet and outlet passages in the rotor and housing, the cam ring and plungers are so positioned within the pump as to give the timing diagram shown in FIG. 4. This is a polar diagram showing plunger motion (at maximum fuel quantity) with respect to the index periods of the intake and discharge passages 4 and 5, and 6 and 7. Successive opening and closing of the indexing of the several passages is noted as DDc and Iolc, with the open period noted by the solid arc lines. Note that the timing sequence for each engine cylinder is intake opens, intake closes, discharge opens, pumping starts, pumping stops and discharge closes.

Ramp compression springs 22 between the cam ring and the ramp cross bars force the ramps toward their outer position. An adjusting sleeve 23 with a conical internal surface is mounted slidably in case 14 so that the conical surface overlaps the conical adjusting nuts on ramp fingers 20. The ramp springs 22 hold the adjusting nuts against the conical surface of the sleeve. 'Ihe sleeve is positioned axially in the case by yoke 24 which engages a groove around the outside of the sleeve near the center, and pivots about yoke pivot shaft 25 which is attached to the yoke and pivotally mounted in the case. As the sleeve is moved from the right to left extremes of its travel by rotation of the yoke pivot shaft, the ramps are moved from their innermost to their outermost positions. The ramps are positioned equally with respect to the cam ring by adjustment of conical nuts 21. The yoke, sleeve and ramps are positioned manually by external lever 32 which is also attached to the yoke pivot shaft, or by a speed control governor (not shown). Yoke travel is stopped in the no-fuel position by stop 26, at which point the ramps and cam lobes are forming a cylindrical cam surface and the ramp cross bar has preferably just contacted the cam ring at point B. The yoke travel is stopped in its maximum fuel position by spring loaded stop button 27 striking stepped stop cam 29. The stop cam is attached to stop cam shaft 30 which is pivotally mounted in the case and positioned by external lever 31 which is also attached to the stop cam shaft, or by a fuel discriminating device (not shown). The four stop surfaces on the stop cam are at four different distances from the pivot shaft center thereby providing a series of four slightly different maximum fuel stop positions for the yoke and consequently four different arbitrary maximum fuel quantities, which the pump can deliver per injection. This adjustment is used to compensate pump output when using fuels having different specific gravities.

Under normal operating conditions, yoke stop spring 28 would `cause stop button 27 to protrude further from the yoke than as shown in FIG. 1 wherein the spring is compressed and button 27 is held firmly against the member which supports it on the yoke, and the yoke motion would be stopped when the button contacted the stop cam surface with the spring 28 in its extended position, at which point the ramp would be positioned for the proper maximum amount of fuel required for normal operation. Applying extra effort to lever 32 would then cause the spring 28 to be compressed and allow the yoke to move closer to the stop cam thereby providing extra plunger travel as required to inject sufficient fuel at crank starting speeds, when the normal maximum fuel delivery is too low because of excessive leakage. Note that with the stop button 27 against the deepest surface of the stop cam with spring 28 compressed, the ramps must be positioned at or less than their maximum outward position where the ramp cross bar strikes the case and housing at points A. FIGS. l and 2 show the apparatus in this position.

The case 14 of the pump is lled with the fuel being used, the fuel entering the case because of leakage along the rotor and plunger surfaces. Fuel leaking along the delivery end of the 'rotor is transferred into the case by passage 33. Fuel is returned to the supply tank (not shown) from the case via outlet connection 34.

The stop cam arrangement disclosed in FIGS. l and 2 can be modified for control of maximum fuel quantity according to inlet air density to the engine as illustrated in FIGS. and 5a, and where applicable, the same numeration is used in these four figures.

In FIGS. 5 and 5a, the stop cam 29 and lever 31 are attached to stop cam shaft 30 as before and operate in the same manner. However, the shaft 30 is rotatably mounted in eccentric bushings 40 which are interconnected by member 41 and are rotatably mounted in the case 14. 0n one side, spacer bushing 42 is inserted between one eccentric bushing and the case to provide for assembly of the parts. Lever arm 43 is attached t-o the eccentric bushing assembly for purposes of rotating it in the case.

As the eccentric bushings are rotated a few degrees clockwise from the position shown in FIG. 5a, the stop cam shaft and stop cam are moved slightly to the right causing the yoke to be stopped at a position of lower fuel ow. If the eccentric bushings are rotated a few degrees counterclockwise, the stop cam moves slightly to the left causing the maximum fuel flow (quantity per injection) to be increased. Obviously, devices well known in the art (not shown) which provide motion according to atmospheric pressure and temperature may be attached to operate lever 43 as temperature and/or barometric pressure change, and thereby regulate the maximum quantity per injection in accordance with intake air density.

Thus, there has been shown and described, an improved, single pumping element distributor type fuel injection pump, which has long leakage paths to provide (a) better and more reliable operation with Volatile fuels, and (b) improved adjustment of maximum fuel output during operation with fuels having different specific gravities and wider variations in intake air density.

Other modifications and variations of the invention as hereinbefore set forth may be made without departingy from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In a fuel injection system for an internal combustion engine, a fuel injection pump comprising a pump housing having an axial bore with fuel inlet and discharge passages leading therefrom and a fuel distributing and pumping means comprising a rotor having an axial passage with fuel inlet and discharge passages leading therefrom adapted to be placed in communication with the corresponding passages in said housing when said rotor is positioned and rotated in said bore, said rotor having a diametral chamber in communication with said axial passage, a pair of plungers housed in said chamber and forming a fuel pumping means therewith, and means located in a section of said housing in constant operative engagement with the outer end portions of said plungers so that when said rotor revolves within said axial bore of said housing said plungers are moved radially outward when said fuel inlet passages in said pump housing and said rotor are in communication with each other and fuel is being admitted to the rotor, and being forced inward when said discharge passages in said pump housing and said rotor are in communication with each other and fuel is being delivered to individual engine cylinders, said last mentioned means including means for regulating the quantity of fuel to be injected by the positive control of the displacement of said plungers and comprising an internal cam ring and pivotally mounted cam surfaces thereon for modifying the profile of said cam ring thereby governing the radial movements of said plungers.

2. In the fuel pump as defined in claim 1, means for preventing back ow of highly pressurized fuel from said discharge passages to said pumping means comprising a check valve positioned therebetween.

3. In the fuel pump as defined in claim 2, said means for positive control of the plunger displacement including a sleeve member mounted in said housing concentric with said cam ring and adapted for axial movement for operative engagement with said pivotally mounted cam surfaces, whereby radial movement of said plungers is 1governed so that the quantity of fuel injected is reguated.

4. In the fuel pump as defined in claim 3, said cam surfaces being pivotally mounted on said cam ring adjacent the cam lobes thereof, means contacting and urging said surfaces into engagement with said sleeve member, said cam surfaces being shaped to provide for maximum quantity fuel pumping when pivoted into outermost circumferential position and when pivoted into innermost circumferential position to eliminate cam action by the formation with said cam lobes of a substantially cylindrical internal cam surface whereby no pumping action occurs.

5. In the fuel pump as defined in claim 4, means for moving said sleeve member axially comprising a fixed pivot yoke and lever interconnected therewith, and adjustable means to control the extremes of yoke travel whereby the axial position of the sleeve is controlled and so the extent of the circumferential movement of said cam surfaces.

6. In a fuel pump as defined in claim 5, the last mentioned adjustable means including a rotatably mounted multiple surface stop cam positioned for engagement with said yoke for providing different maximum yoke travel positions and thereby providing for different maximum fuel quantities for pump delivery per injection, depending on the surface of the stop cam engaged.

7. I u a fuel pump as defined in claim 6, said yoke having a spring loaded contact member for engaging a surface of said stop cam whereby additional force applied to said yoke will compress said spring and thereby cause said yoke to move closer to said stop cam thereby effecting an increase in maximum fuel delivery.

8. In a fuel pump as defined in claim 7, said stop cam including a shaft mounted in said housing in rotatable eccentric bushings whereby variation of the angular position of said bushings changes the position of the surfaces of said stop cam with respect to said yoke thereby to provide further adjustment of the maximum fuel yoke position. f

9. In a fuel pump as defined in claim 8, means for de termining the position of said ysurfaces of said stop cam, said means being subject to variations in atmospheric pressure and temperature whereby the maximum quantity of fuel per injection is regulated in accordance with intake air density.

10. In an internal combustion engine, a single pumping unit distributor type fuel injection pump including a pump housing having an axial bore therein, a fuel inlet passage and discharge passages for receiving pressurized fuel in communication therewith, a rotor adapted to be Ipositioned within said bore having an axial passage and a plurality of radial passages leading therefrom and serving as the inlet and discharge for pressurized fuel passing through said axial 'bore in said rotor into said discharge passages, said rotor having a portion with a radial chamber therein in communication with said axial passage, and pumping means comprising a plunger housed in said chamber for reciprocating movement, means for preventing the flash vaporization of fuel in said pump comprising means for positive control of said reciprocating movement of said plunger including a cam construction for constant operative engagement with said plunger whereby the rotation of said rotor moves said plunger in inward pumping motion to force pressurized fuel from said chamber and said axial passage into said discharge passages in said Ihousing, said cam construction including an internal cam ring and cam surfaces pivoted thereon comprising a ramp, means mounted in said housing concentric with said cam ring in operative contact with said ramp for governing the extent of circumferential movement thereof whereby the amount of vfuel pumped per injection is controlled, and means for preventing return of pressurized fuel from said discharge passages comprising valve means in said axial passage.

11. In a single pumping unit distributor type fuel injection pump comprising a pump housing having an axial bore with fuel inlet and discharge passages leading therefrom and fuel distributing and pumping means compris- `ing a rotor having an axial passage with fuel inlet and discharge passages leading therefrom adapted to be placed in communication with the corresponding passages in said housing when said rotor is positioned and rotated in said bore, said rotor having a diametral chamber in communication with said axial passage, a pair ofV plungers housed in said chamber and forming a fuel pumping means therewith, and means located in a section of said housing in operative engagement with the outer end portions of said plunger so that when said rotor revolves within said axial bore of said housing said plungers are moved radially outward when said fuel inlet passages in said pump housing and said rotor are in communication with each other and fuel is being admitted to the rotor and forced inward when said discharge passages in -said pump housing and said rotor are in communication with each other and fuel is being delivered through individual discharge passages, means for preventing deterioration of fuel injection characteristics including fuel flashing comprising, in combination therewith, means for positively limiting outward movement of -said pump plungers comprising an internal cam ring and movable cam surfaces pivotally mounted thereon and a sleeve member mounted in said housing concentric with said cam ring and adapted for axial movement for operative engagement with said movable cam surfaces thereby controlling the radial movement of said plungers, and means for preventing back flow of fuel from discharge passages of said pump comprising valve means positioned in said axial bore.

12. In a pump as defined in claim 11, said movable cam surfaces of said means for positively limiting radial movement of said pump plungers including .adjustable members, said sleeve member having a tapered inner surface for engaging with said adjustable members whereby radial movement of said plungers is controlled.

13. In a single pumping element distributor type fuel injection pump comprising a pump housing having an axial bore and with fuel and discharge passages leading therefrom and a fuel distributing and pumping means comprising a rotor having an axial passage and with fuel inlet and discharge passages leading therefrom adapted to be placed in communication with the corresponding passages in said housing when said rotor is positioned and rotated in said bore, said rotor having a diametral cham- Aber in communication with said axial passage thereof, a

pair of plungers housed in said chamber and forming a pumping means therewith, a cam roller and a cam follower shoe holding said cam roller as a roller-follower assembly positioned at each of the outer ends of said chamber in contact with the outer ends of said plungers therein, in-

ternal cam means located in a section of said housing in constant contact position with said roller-follower assembly so that when said rotor revolves within said axial bore of said housing said plungers are moved radially outward when said fuel inlet passages in said pump housing and said rotor are in communication with each other and fuel s being admitted to said rotor and being forced inward when said discharge passages in said pump housing and said rotor are in communication with each other and fuel is being delivered to individual discharge passages, said cam means comprising an internal cam ring having spaced cam lobes thereon, movable ramps having inner edges defining adjustable cam surfaces pivoted to said cam ring edjacent said cam lobes and extending circumferentially therebetween, and -means between said cam ring and said ramps urging the latter rotatably about their pivots and a sleeve member vmounted in said housing concentric with said cam ring'in operative engagement with the unpivoted ends of said ramps to insure constant positive control of the radial movement of said plungers.

14. In a fuel injection pump as defined in claim 13, a fixed pivot yoke operatively engaged with said sleeve member for control of the axial movement thereof, and means determining the extreme positions of said yoke whereby the maximum and minimum quantities of fuel pumped per injection is delimited.

15. In a fuel injection pump as defined in claim 14, said last mentioned means comprising an adjustable stop member at one end travel position of said yoke so that said ramps are urged inwardly whereby said cam surfaces thereon form with said cam lobes a substantially/'cylindrical cam surface whereby no fuel is pumped when said rotor is rotated, and a multiple surface stop cam at the other end travel position of said yoke whereby the maxi'- mum quantity of fuel pumped per injection is governed.

16. In a fuel injection pump as defined in claim 15, said ramps comprising a pair of side rails joined by a cross bar and straddling said cam ring, said means urging said ramps rotatably about their pivots comprising spring means positioned between said cross bar and said cam ring,l adjustable means extending axially towards said sleeve member supported by the unpivoted ends of the side rails adjacent thereto and in contact therewith,

and means for preventing back flow of fuel fromV Vsaid discharge passages of said pump comprising check valve means. Y

17. In a fuel pump as defined in Vclaim 16, control means for determining the position of said stop cam, said control means being subject to variations in atmospheric pressure and temperature whereby the maximum quantity of fuel pumped per injection is regulated in accordance with intake air density.

References Cited UNITED STATES PATENTS Y 2,263,786 11/1941 Rumpp 103-7-38 2,393,175 1/ 1946 Laskey 103-38 2,420,806 5/1947 Anderson 103-161 2,935,062 5/1960 Aldinger etal 103-2.l 3,000,318 9/ 1961 Volossevich l03-2.1 3,043,228 7/ 1962 Bennett 10S-38 3,046,905 7/ 1962 Davis 103-38 3,131,604 5/1964 Orshansky 103-38 3,146,715 9/1964 Knudsen 103--166 DONLEY J. STOCKING, Primary Examiner.

MARK NEWMAN, Examiner.

W. I. KRAUSS, Assistant Examiner.

Claims

1. IN A FUEL INJECTION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE, A FUEL INJECTION PUMP COMPRISING A PUMP HOUSING HAVING AN AXIAL BORE WITH FUEL INLET AND DISCHARGE PASSAGES LEADING THEREFROM AND A FUEL DISTRIBUTING AND PUMPING MEANS COMPRISING A ROTOR HAVING AN AXIAL PASSAGE WITH FUEL INLET AND DISCHARGE PASSAGES LEADING THEREFROM ADAPTED TO BE PLACED IN COMMUNIATION WITH THE CORRESPONDING PASSAGES IN SAID HOUSING WHEN SAID ROTOR IS POSITIONED AND ROTATED IN SAID BORE, SAID ROTOR HAVING A DIAMETRAL CHAMBER IN COMMUNICATION WITH SAID AXIAL PASSAGE, A PAIR OF PLUNGERS HOUSED IN SAID CHAMBER AND FORMING A FUEL PUMPING MEANS THEREWITH, AND MEANS LOCATED IN A SECTION OF SAID HOUSING IN CONSTANT OPERATIVE ENGAGEMENT WITH THE OUTER END PORTIONS OF SAID PLUNGERS SO THAT WHEN SAID ROTOR REVOLVES WITHIN SAID AXIAL BORE OF SAID HOUSING SAID PLUNGERS ARE MOVED RADIALLY OUTWARD WHEN SAID FUEL INLET PASSAGES IN SAID PUMP HOUSING AND SAID ROTOR ARE IN COMMUNICATION WITH EACH OTHER AND FUEL IS BEING ADMITTED TO THE ROTOR, AND BEING FORCED INWARD WHEN SID DISCHARGE PASSAGES IN SAID PUMP HOUSING AND SAID ROTOR ARE IN COMMUNICATION WITH EACH OTHER AND FUEL IS BEING DELIVERED TO INDIVIDUAL ENGINE CYLINDERS, SAID LAST MENTIONED MEANS INCLUDING MEANS FOR REGULATING THE QUANTITY OF FUEL TO BE INJECTED BY THE POSITIVE CONTROL OF THE DISPLACEMENT OF SAID PLUNGERS AND COMPRISING AN INTERNAL CAM RIN AND PIVOTALLY MOUNTED CAM SURFACES THEREON FOR MODIFYING THE PROFILE OF SAID CAM RING THEREBY GOVERNING THE RADIAL MOVEMENTS OF SAID PLUNGERS.