US2576451A - Fuel injection pump - Google Patents

Description

Nov- 27, 1951 J. DlcKsoN ET AL 2,576,451

FUEL INJECTION PUMP Filed March 17, 1948 Patented Nov. 27,1951

FUEL INJECTION PUMP John Dickson, Huntington Woods, and Kenneth L. Hulsing, Plymouth, Mich., assignorato General Motors Corporation, Detroit,

poration of Delaware Mich., a cor- Application March 17, 1948, Serial No'. 15,458

14 claims. l

This invention generally relates to fuel injectors and more particularly to improvements in fuel injection pumps for internal combustion engines.

The principal object of this invention is to provide in a fuel injection pump relatively movable pump plunger and sleeve members forming a fuel compression space therebetween, each having few cooperating fuel passages, ports and control edges of simple form to vary the pressure and volume of the fuel in this space during the fuelfllling, fuel compression and pressure discharge strokes and providing on the discharge stroke, by-pass from. trapping and compression of the fuel ln and controlled start and end of discharge of the compressed fuel from the fuel compression space so that controlled quantities of fuel are discharged therefrom and injected in an internal combustion engine at more uniform pressure, velocity and spray pattern over the range of relative velocity of movement between the plunger and sleeve members.

The combined means by which this object is accomplished will become apparent by reference to the following detailed description and drawings of two different modifications of fuel injection pump mechanisms incorporating features for providing improved fuel injection characteristics for internal combustion engines.

Figure 1 of the drawing is a longitudinal sectional view of one form of fuel injection pump of the fluid pressure operated type.

Figure 2 is a transverse sectional view taken on line 2-2 of Figure 1.

Figure 3 is a longitudinal sectional view of another form of fuel injection pump of the mechanically operated type.

As best illustrated in Figure 1 the fiuid pressure operated fuel injection pump comprises a pump body I having an axial bore 3 provided with larger'diameter counterbores 5-6 at opposite ends. The pump body is shown inserted in uid tight relation in a fuel pressure supply cavity 1 in a cylinder head 3 of an internal combustion engine, by means of gaskets I--II between the body and engine cylinder head so that the body counterbore opens into the engine combustion chamber adjacent the inner surface of the cylinder head.

A hollow cylindrical sleeve I3 having an external packing ring I4 is reciprocal in the body bore 3 and is provided with an external flange I5 shown in sliding contact with a smaller diameter inner end portion I1 of the counterbore '6. A iianged annular closure member 2| having a gasket 23 thereon is seated on an internal flange in the body counterbore 6 and a packing ring 25 is provided in an internal annular groove in the closure member so that the packing ring is in sliding contact with the external surface of the reciprocal sleeve I3. A clamping head 21 is seated on the outer faces of the body I vand closure member 2| to clamp the closure member in uid tight relation with the body and sleeve and to retain the body in uid tight relation in the cavity 1 of the engine cylinder head 9. Suitable injection pump hold-down means, generally indicated at 28, are provided on the engine cylinder head 9 to engage the clamping head 21 of the injection pump for clamping it in place as shown.

A plunger 30 having a smaller diameter outer end portion 3I`is rotatably mounted in an opening in the clamping head 21 coaxial with the bore in the reciprocal sleeve I3 into which the inner smaller diameter end of the plunger 30 projects. A lever 33 is secured to the outer end 3l of the rotatable plunger 30 for adjusting it angularly with respect to the head 21 and bore of the sleeve I3 and to prevent reciprocal movement thereof of the plunger 30. A stack of dished spring washers 35 or suitable helical spring means and a thrust collar 31 are placed around the outer end of the rotatable plunger 30 and within a cavity 33 in the clamping head 21. The thrust collar 31 is positioned between the outer end of the head cavity 39 and the stack of spring washers 35 and the other end of the stack of washers contacts the outer end of the reciprocal sleeve I3 and urges it inwardly of the body bore 3 and the exterior flange I 3 on the plunger 29 is accordingly urged inwardly and slides in the reduced diameter portion I1 of the outer end body counterbore 6.

The inner end of the reciprocal sleeve I3 is closed by a check valve seat member 41 which is seated thereon by a fuel discharge nozzle 4t* which is clamped thereto by an actuating piston 45 threaded on the outer end of the sleeve I3. The piston 45 is provided with a longitudinal opening coaxial with the body bore 3 and is provided with an internal flange in clamping engagement with a flange on the nozzle 43 which has a tip portion projecting out of the piston opening and into the engine combustion chamber. The piston 45 is provided with external packing rings 41 slidable into the inner end counterbore 5 of the body I when the compression pressure in the engine compression chamber exerts suflicient force on the piston to overcome the force exerted by the spring washers 35 acting on the other end of the reciprocal sleeve I3. The piston 45 and sleeve I3 reciprocal thereby is prevented from rotating in the body I by a pin 49 threaded in the body I and extending into a longitudinal extending external slot 4I in the sleeve I3, as best shown in Figure 2.

The space in the outer end of the bore of the reciprocal vsleeve I3 between the inner end face of the reduced diameter portion 29 of the rotatable plunger 30 and the check valve seat 4I, generally indicated at 53, serves as a fuel pumping chamber. The wall of this chamber is formed by longitudinally spaced internal grooves 55-51 in the sleeve bore forming a land 59 therebetween of the same diameter as the plunger bore.

The pump body I is provided with a radial fuel inlet passage 6I extending from the fuel pressure supply cavity 'I to the body bore 3. The outer end of the fuel inlet passage is enlarged at 53 and a fuel inlet filter element 65 is located therein. The reciprocal sleeve I3 has a flat 61 formed thereon which is in continuous registration with the fuel inlet body passage 6I for all relative positions of the plunger with respect thereto. A drilled passage in the reciprocal sleeve I3, serving as a combined fuel inlet and by-pass port 69, extends radially from the flat 61 on the sleeve I3 to the interior of the bore thereinand another passage spaced longitudinally outwardly from the port 69 and extending diametrically from the flat part way through the sleeve I3 forms a fuel inlet and relief port 1I and a fuel dis- ,charge port 12 diametrically opposite the port 1I.

`The rotatable plunger 29 is provided with a comlaxial passages 15-11 in the rotatable plunger 29 lead from the plunger groove 13 to the inner end face thereof and' therefore to the pumping chamber 51 to permitfuel under pressure to enter and fill this chamber and these plunger passages. The rotatable plunger 29 is also prolvided with a helical fuel discharge groove 13 normally registering with the inlet and relief port 1I to permit fuel under pressure to also illl this plunger groove. A longitudinal fuel discharge passage 19 extends from the discharge port 12 in the reciprocal sleeve I3 to registering annular grooves 3| formed in the engaging faces of the sleeve I3 and check valve seat 4I, from which a discharge passage 83 extends to the center of the outer face of the valve seat. An axial discharge passage 35 is formed in the nozzle 43 having a counterbore 36 adjacent the inner end face and containing a check valve disk 31 provided with peripheral grooves for establishing communication between the discharge passage of the nozzle and the discharge opening 33 in the seat 4I when the disk 31 is spaced from the seat 4I. Fuel spray discharge openings 39 extend radially and axially outwardly from the nozzle passage 35 through the tip of the nozzle which projects through the piston 45 and into the engine combustion chamber.

With the pump sleeve I3 and plunger 29 in the normal position. as shown at the end of the fuel filling stroke with the fuel inlet passages, ports, grooves and pumping chamber filled with fuel under pressure from the fuel pressure supply cavity 1 in the engine cylinder head as described above, the following events occur upon inward movement of the piston 45 and sleeve I3 on the discharge stroke relative to the pump body I and plunger 33 rotatable therein when the engine compression pressure applied to the piston is sufflcient to overcome the force of the spring washers 35.

Initial movement of the piston 45 and sleeve I3 on the fuel discharge stroke causes the external flange I5 on the sleeve to move out of the smaller diameter portion I1l of the body counterbore 6 and causes displacement and by-pass of fuel out of the pumping chamber 53 through the passages 15-11 and groove 13 in the rotatable plunger and port 69 in the reciprocalsleeve I3 until this port moves out of register with the groove 13 to trap and compress the fuel in the pumping chamber 53 and -into register with the bottom of the bottom edge of the small diameter portion I1 of counterbore 6 in the body to allow fuel supply pressure to enter this counterbore. The inlet and relief port 1I in the sleeve simultaneously moves out of register with the helical groove 13 of the rotatable plunger 29 to trap fuel in this groove. Upon a further and rapid rise in the engine compression pressure the piston 45 and sleeve I3 continue to move inwardly and compress the fuel trapped in the pumping chamber 53 which also opposes this movement along with opposing force of the spring washers 35. The inner edge of the internal groove 55 of the reciprocal sleeve next registers with the helical discharge groove 13 in the rotatable plunger 29 to equalize the pressure therein with that in the pumping chamber 53. This varies the force opposing inward movement of the/piston 45 and sleeve I3. After a predetermined travel the discharge port 12 in the reciprocal sleeve I3 then registers with the helical discharge groove 18 of the rotatable plunger to start discharge of the compressed fuel from the pumping chamber 53 through the helical discharge groove 13, discharge port 12 and passages 19-3 I-83-85 and 39 in the sleeve I3 and plunger 29, valve seat 4I and nozzle 43 and directly into the engine combustion chamber causing fuel injection and combustion of fuel in the engine combustion chamber. The land 59 in the bore of the sleeve I3 next moves over the end of the rotatable plunger 29 preventing any further compression of the fuel in the internal groove portion 55 of the pumping chamber inside the land 59 and thereby stops further discharge and injection therefrom and to retrap and further compress the fuel in the outer internal grooveportion 51 of the chamber and thereby provide a hydraulic lock between the plunger and sleeve to stop further movement of the piston 45 and sleeve. The flange I5 of the sleeve is in the inner end counterbore of the anged closure member 2| which is supplied with fuel at supply pressure through the body counterbore 6, as described above, to provide an additional hydraulic lock to also stop movement of the piston and sleeve on the discharge stroke to prevent metal to metal contact between this flange I5 and closure member 2 I.

It will be evident that varying the longitudinal spacing of the grooves 13-18 of the rotatable plunger 29 or the Width thereof causes different compression and pressure of fuel trapped in the pumping chamber prior to the start of injection. With the spacing and width of these grooves determined, angular adjustment of the rotatable plunger helical discharge groove 18 varies the start of injection relative to the end of injection which is determined by the movement of the sleeve land 59 past the inner end face of the rotatable plunger 29 to determine the end of the effective discharge or injection stroke of the fuel injection pump and the amount of fuel injected during this time. The relative longitudinal displacement of the internal grooves 55-51 and the land 59 therebetween of the reciprocal sleeve I3 and their widths may be changed to vary the end of injection and control the compression of fuel andl pressure in the pumping chamber or portions thereof to suit different compression pressure values for different engines.

The modified fuel injection pump structure shown in Figure 3 also includes a relatively movable plunger and sleeve of similar form to that previously described. This pump includes a pump body having an axial bore |03, a sleeve |05 having an external flange |06 seated on one end face of the body by a check valve seat member |01 which is seated on the outer end of the sleeve by a fuel nozzle 00 in seating engagement therewith and having an external ange |09 which is engaged by an internal flange of a hollow cap member ||0 threaded on the fuel pump body |0I. A plunger is reciprocal in the sleeve |05 and the space in the sleeve between the inner end of the plunger and the check valve seat serves as a fuel pumping chamber. which is generally indicated at |3. It will be noted that the sleeve |05 is provided with an internal groove i|5 forming the inner wall portion of the pumping chamber adjacent the outer end of the sleeve bore closed by the check valve seat member |01. The cap ||0 is provided with an external conical seating surface ||1 which is seated on a similar complementary seating surface in an opening of an engine cylinder head, not shown, and communicating with the engine combustion chamber; suitable hold-down means being provided on the cylinder head, similar to that indicated generally at in Figure l, to hold the cap l0 seated in the cylinder head opening.

The plunger is provided with an external flange ||0 at the outer end shown positioned between an internal flange of a hollow follower guide ||9, slidable in the outer end of the body bore |03, and a follower |2| held in the hollow guide by a pin |23. The hollow guide I9 is provided with a longitudinal slot in which the inner end of a pin |21 secured in an extension of the body |0| projects, to prevent rotation of the follower |2| and guide ||.9. A helical compression spring |29 is placed between the body |0| and an externalflange |3| of the guide ||9 and normally urges vthe guide, follower and plunger outwardly of the body and sleeve on the fuel filling stroke to the position shown in Figure 3 so that the pin |21 in the body contacts the inner end of the guide slot |25. Movement of the plunger inwardly of the body and sleeve on the fuel discharge stroke is accomplished by a suitable engine operated rocker lever |33 having a roller |35 thereon in engagement with the follower |2|. l

The plunger is provided with a hexagonal portion |31 adjacent the outer end which is slidable in an internal hexagonal portion of a pinion |39 located between a hollow .spacer |4| in the inner end of a counterbore of the-body and in ports and control edges which are. similar to those previously described in the injection pump shown in Figures 1 and 2. A fuel pressure supply passage comprising radial and longitudinal communicating drilled passages |61-|69, the latter opening into the space |5| between the cap ||0 and sleeve |05. The sleeve |05 is provided with a combined fuel inlet and by-,pass port |53 opening into the space |5| and a drilled passage extending dlametrically part way through the sleeve forms a combined inlet and relief port |55 opening into the space |5| and a discharge port |51 diametrically opposite'the port |55. A longitudinal discharge passage |59 in the sleeve |05 leads from the discharge port |55 to registering annular grooves |6| in the seated surfaces of the sleeve and check valve seat. A discharge passage |63 extends from the annular grooves |6| to the center of..the outerface of the check valve seat |01 and opens into a counterbored portion |65 of an axial bore |61 in the fuel nozzle |03. Fuel spray openings |69 are provided in the top of the nozzle and these openings extend radially and angularly outwardly from the axial bore |61. A valve disk |1| is located in the counterbored portion |65 ofthe fuel nozzle and is provided with peripheral grooves by which fuel is discharged past the disk when it is spaced from the center opening in the valve seat member |01.

The plunger is provided with a combined fuel inlet. by-pass and relief groove |13 of semicircular form and radial and axial passages |15|11 leading therefromV to the pumping chamber |I3. The plunger groove |13 registers with the combined inlet and by-pass port |53 of the sleeve |05 when the plunger is at the end of the fuel filling stroke to cause filling ofthe pumping chamber and the above passages with fuel. With the plunger in this position it will be noted that a helical discharge groove |19 provided thereon registers with the combined inlet and relief port |55 of the sleeve to likewise cause fuel filling of this groove.

Initial inward movement of the plunger by the rock lever |33 against the force of the spring |29 causes fuel in the pumping chamber |.|3 to be by-passed outwardly therefrom through the plunger passages |15-|11, plunger groove |13 and sleeve inlet aand by-pass port |53 until this groove moves out of register with this port and traps fuel inthe pumping chamber. The helical plunger groove |13 also moves out of register with the inlet and relief port |55 of the sleeve |05 at this time and traps fuel in the helical groove. Further inward movement of the plunger causes compression and pressure increase of the fuel trapped in the pumping chamber. 'I'he helical plunger groove |19 then registers with the internal groove ||5 of the sleeve and equalizes the pressure'therein with that of the trapped and compressedfuel in the pumping chamber after which the helical groove |19 registers with the discharge port |51 to start discharge of the compressedfuel through this groove and port from the pumping chamber ||3 to and through the passages |59, |6l, |63, |65, |61 in the sleeve |05, seat'member |01 and nozzle |61 and outwardly through the fuel spray openings |69 in the nozzle tip into the engine combustion chamber. Discharge of fuel continues until the plunger inlet and relief groove |13 registers momentarily with the sleeve inlet and relief port to relieve the\pressure in the pumping chamber and passages |15|11 momentarily as the inner end surface of the plunger immediately therefurther release of pressure from this inner groove portion of the pumping chamber ||3 and to end fuel discharge therefrom, however, relief of pres'- sure from-the outer or end boreportion of the pumping chamber continues to relieve the mechanical load on the engine driven rocker lever |33.

It will be evident that the mechanically operated fuel injection pump, shown in Figure 3, has similar-structural details to that of the compression pressure operated pump, shown in Figures l and 2n 'Ihe compression and pressure of fuel trapped in the compression chamber I|3 of the pump shown in Figure 3 is determined by the amount of plunger movement after the plunger grooves |`|3I18 move past the sleeve ports I53-I55 until the plunger discharge port registers with the sleeve discharge port |51 which causes the start of discharge and injection of fuel into the engine combustion chamber. As previously mentioned the width of the plunger grooves |13-II9 and longitudinal spacing and also the angular adxstment of the plunger by the rack |45 and pinion |39 varies the amount of fuel compression and pressure prior to the start of injection relative to end injection which is determined by momentary relief of pressure in the pumping chamber immediately followed by movement of the end of the plunger past the internal groove ||5 forming the inner wall portion of the pumping chamber. .The mechanically operated injection pump then relieves the pressure in the last part of the discharge stroke to relieve the load on the rocker lever |33 actuating the plunger on the discharge stroke. When the plunger is returned on the filling stroke the compression space ||3 is filled by entrance of fuel from the space I5I through registration of the combined inlet and discharge sleeve port |53 and the combined inlet and relief plunger groove |13 and connecting passages I15--I11 at the start of the filling stroke and also near the end of the filling stroke by registration of the combined inlet and by-pass sleeve port |53 and the plunger inlet and relief groove |13 and connecting passages lli-|11.

We claim: y

'1. In a fuel injection pump, a sleeve closed at one end and having an internal groove adjacent the closed end, a pair of fuel supply ports and a fuel discharge port, a plunger in the sleeve having a pair of grooves normally registering with the sleeve supply ports, one groove serving asia discharge groove, and a passage vfrom the other l one end and having an internalgroove adjacent groove leading to the inner end of the plunger ternal groove of the sleeve and forming part of a fuel pumping chamber wall between the inner end of the plunger and the closed endA of the sleeve to cause fuel filling of these plunger grooves and passages and the pumping chamber, and means for causing relative movement between the sleeve and plunger to initially cause closure of the sleeve supply ports by the plunger tojtrap and compress the fuel in the pumping chamber, to next cause registration of the sleeve discharge port `and internal groove with the plunger discharge groove and thereby cause discharge of the compressed fuel and to then cause alignment between the internal sleeve groove and' inner end of the plunger to end fuel discharge from the chamber.

2. In a fuel injection pump, a sleeve closed at .which is normally positioned adjacent the inthe closed end. a pair' of fuel supply ports and a fuel discharge port. a plunger in the sleeve having a pair of grooves. one groove normally registering with a sleeve supply port and a passage in the plunger leading therefrom to the inner end of the plunger which is normally positioned adjacent the internal sleeve groove forming part of a fuel pumping chamber'between the inner end of the plunger and closed end of the sleeve, the other plunger groove being of helical form and normally registering with the other sleeve supply port so that the plunger grooves and passages and the pumping chamber are lled with fuel, means for-causing relative axial movement between the plunger and sleeve to initially cause trapping and compression of the fuel in the pumping chamber and plunger passages leading thereto by closure of the sleeve supply ports byv the plunger, to then cause the helical plunger groove to register with the internal sleeve groove and discharge port to cause the start of discharge of the compressed fuel and to then cause alignment of the internal sleeve groove with the inner end of the plunger to'end fuel discharge and means for causing relative angular motion between the sleeve and plunger to vary the start of fuel discharge.

3. In a fuel injection pump, a sleeve closed at one end and having an internal groove adjacent the closed end, a fuel supply and by-pass port. and a pair of ports in the same plane between the fuel supply and by-pass port and internal groove. one port of this pair of ports serving a`s a supply port and the other port of this pair of ports serving as a discharge port, a plunger in the sleeve having a groove normally registering with the supply port and passages leading therefrom to the inner end of the plunger which is normally positioned adjacent theinternal sleeve groove which forms part of the fuel pumping chamber between the inner end of the plunger the pumping chamber and plunger grooves and passage, to next cause registration of the sleeve discharge port and internal groove with the helical plunger discharge groove to cause the start of discharge of the compressed fuel from the chamber and finally to cause alignment of the inner end of the plunger with the internal sleeve groove to end discharge of fuel from the chamber and means causing relative angular movement between the sleeve and plunger to vary the start of discharge of the-compressed fuel from the pumping chamber.

.4. In a, fuel injection pump, a sleeve closed at one end and having an internal groove adjacent the closed end, a fuel supply port and a pair of diametral ports between the supply port and internal groove. one port of this diametral pair serving as a second supply port and the other serving as a discharge port, a plunger in the sleeve having a transverse supply groove, a passage leading therefrom to the inner end of the plunger and a helical discharge groove. means causing relative axial movement between the of the sleeve supply ports with a respective plunger groove and positioning the inner end of the plunger adjacent the internal sleeve groove so that this groove serves as part of a pumping chamber between the inner end of the plunger and closed end of the sleeve. a second means causing opposite relative axial movement between the sleeve and plunger to initially cause closure of the sleeve supply ports by the plunger to trap and compress the fuel in the plunger grooves and passage and in the pumping chamber, to next cause registration of the helical discharge plunger groove with the internal groove and discharge port of the sleeve to control the start of discharge of the compressed fuel and to finally cause alignment between the inner end of the plunger and internal groove to the sleeve to control the end of fuel discharge, and a third means causing relativegangular movement between the plunger and sleeve to vary the start relative to the end of fuel discharge.

5. In a fuel injection pump, a pump body having a bore and fuel pressure supply passage opening therein, a sleeve in said bore having a closed end and an internal groove adjacent the closed end, two axially spaced ports in continuous register with the cylinder supply passage, a discharge port in the plane of one of the axially spaced ports, and a discharge passage leading therefrom, a plunger in the sleeve and having two grooves and a passage leading from one to the inner end face, said other plunger groove having a helical control edge, means normally positioning the sleeve and plunger so that the communicating plunger passage and groove are in communication with one of the sleeve ports in communication with the cylinder fuel pressure supply passage to flll the space including the vinternal sleeve groove between the inner end face of the plunger and closed end of the sleeve and so that the other plunger groove is in communication with the other sleeve port in communication with the cylinder fuel supply passage in order to fill these plunger passages and the space between the plunger and sleeve with fuel, means for causing relative axial movement of the plunger and sleeve from the normal position to rst cause closure of the sleeve supply ports by the plunger to trap and compress the fuel in the above plunger passages and the space between the plunger and sleeve, to next establish communication between the internal groove and discharge port of said sleeve with the helical-edge of the other plunger groove to control the start of fuel discharge of the compressed v fuel from the helical plunger groove and space between the plunger and sleeve through the sleeve discharge port and to finally cause overlapping of the internal sleeve groove and inner end of the plunger to cut off fuel discharge, and a second means for causing relative angular movement between the plunger and sleeve to vary the start of fuel discharge.

6. In a fuel injection pump, a sleeve closed at one end having an internal groove adjacent the closed end serving as a fuel pumping chamber, three separate ports and a discharge passage leading from one port serving as a discharge port, said other two ports being in continuous communication with a source of fuel, a plunger in the sleeve having two grooves and a passage leading from one groove to the inner end face and pumping chamber, the other plunger groove serving as a discharge groove, means resiliently urging the plunger outwardly of the chamber to cause closure of the sleeve discharge port and registration of the plunger grooves with the other sleeve ports to fill the chamber with fuel, and means for moving the plunger toward and into the chamber, to initially trap and compress the fuel in the chamber by closure of the two sleeve ports in communication with the fuel source by the plunger, to next cause registration of the interna1 groove and discharge port of the sleeve with the plunger discharge groove to start discharge of the compressed fuel and to then cause momentary registration of the groove having the passage leading to the chamber with the other port in communication with the fuel source to momentarily relieve the pressure therein and immediately thereafter to finally cause closure of the internal sleeve groove by the inner end surface of the plunger to cut oft fuel discharge from the chamber.

7. In a fuel injection pump, a sleeve closed at one end and having an internal groove adjacent the closed end, a fuel inlet port and circumferentially spaced relief and discharge ports axially spaced from the inlet port, said inlet and relief ports being in continuous communication with a. source of fuel pressure, a plunger in the sleeve to form a pumping chamber including the interna] sleeve groove between the closed end of the sleeve and the inner end of the plunger, said plunger having a transverse inlet groove and passage leading therefrom to the inner end face and a helical discharge groove, means normally causing relative movement of the sleeve and plunger to cause closure of the discharge port and to cause each of said other ports to register with one of said plunger grooves to cause fuel filling of said chamber, another means for causing relative movement between the sleeve and plunger to initially cut off fuel filling and trap and compress the fuel in the chamber, to next cause registration of the helical plunger discharge groove with the internal groove and discharge port of the sleeve to start discharge of the compressed fuel from the chamber and finally cause registration of the transverse plunger inlet groove and a sleeve relief port and registration of the inner end of the plunger with the internal groove to stop discharge of fuel from the chamber and means for rotating the plunger in the sleeve to vary the start of fuel discharge.

8. In a fuel injection pump, a pump body having a bore and a fuel pressure supply passage leading thereto, a sleeve in said bore and having a closed end, an internal groove adjacent the closed end serving as a fuel pumping chamber, three separate ports and a discharge passage through the closed end and communicating with one port serving as a fuel discharge port, means for securing the sleeve to the body so that the other two sleeve ports therein are in communication with the pressure supply passage of the body, a plunger having two grooves, one serving as a discharge groove and the other communicating with a passage extending to the inner end face and the pumping chamber, resilient means normally urging the plunger outwardly of the chamber to a fuel filling position to close the sleeve discharge port and passage and cause each plunger groove to register with one of the other two ports, and means for moving the plunger into the chamber to close all three sleeve ports and trap and compress the fuel in the chamber and plunger grooves and passages and then cause the plunger discharge groove to register with the sleeve discharge port and passage and also with the internal groove of the chamber to start discharge of the compressed fuel and to then cause the other plunger groove and passage to momentarily register with the other sleeve port in communicating with the fuel supply passage and immediately thereafter to cause the internal sleeve groove to be covered by the inner end surface of the plunger thereby momentarily relieving the pressure in the chamber immediately before cut oif discharge from the chamber.

9. In a fuel injection pump, a pump body having a fuel supply passage, a sleeve having a closed end slidable in the body and including a pair of vports in continuous register with the body fuel the sleeve relative to the body and plunger tov cause registration of the sleeve supply ports and plunger grooves to cause filling of the pumping chamber with fuel and for also opposing inward movement of the sleeve from this normal position relative to the body and plunger bv application of pressure on the outer closed end to initially trap and compress the fuel in the pumping chamber, to next cause registration of the discharge port and internal groove of the sleeve with the plunger discharge groove whereby the compressed fuel is discharged from the pumping chamber through the discharge port and to finally cause alignment of the internal sleeve groove with the inner end of the plunger to end discharge from the pumping chamber.

10. In a fuel injection pump, a pump body having a fuel pressure supply passage, a sleeve closed at one end and slidable in the body and including an internal groove adjacent the closed end, a pair 'of axially spaced supply ports in continuous register with the body supply passage and a discharge port and discharge passages leading outwardly therefrom through the closed end, a plunger in the body and extending into the sleeve and including a pair of grooves, one serving as a discharge groove and passages leading from the othergroove to the end face and space serving as a pumping chamber including the internal groove in the sleeve, means normally positioning the sleeve relative to the body and plunger and to cause registration of the sleeve supply ports with the plunger grooves to ll the pumping chamber with fuel pressure and toresiliently oppose inward movement of the sleeve relative to the body and plunger upon pressure application on the closed end to close the sleeve supply ports and trap and compress the fuel in the pumping chamber, to then cause registration of the internal sleeve groove and discharge port with the plunger discharge groove to start discharge of the compressed fuel from the pumping chamber and to finally cause registration of the internal sleeve groove with the inner end of the plunger to end fuel discharge, retrap and compress fuel in the pumping chamber and thereby stop further inward movement of the sleeve.

11. In a fuel injection pump, a pump body having a fuel pressure supply passage. a sleeve reciprocal in the body and closed at one end to serve as a piston and including an internal groove adiacent the piston, a pair of fuel pressure supply ports spaced axially apart and in continuous rcsspring for normally positioning the sleeve rela-v tive to the body and plunger to cause registration of the sleeve supply ports and plunger grooves to ll these grooves and the pumping chamber with fuel under pressure, and for resiliently opposing inward movement of the sleeve by pressure application on the piston to trap and compress the fuel in the pumpingchamber, to next cause registration of the internal groove and discharge port and passages of the sleeve with the helical edge of the discharge groove of the plunger to start discharge of the compressed fuel from the pumping chamber and to finally cause alignment of the internal sleeve groove with the inner end of the plunger to end discharge and to retrap and Icompress fuel in the pumpingchamber and thereby limit further inward movement of the sleeve by the piston.

12. In a fuel injection pump, a pump body having a bore, a fuel pressure inlet passage opening into the bore and counterbored end portions, a sleeve reciprocal in the body bore having an enlarg-ed closed end piston portion slidable in one end counterbore of the body, the sleeve having axially spaced supply ports in continuous communication with the body supply passage, a discharge port and passages leading therefrom outwardly of the piston portion and an external flange slidable in the other end body counterbore, a plunger rotatable on the body and in the sleeve and including axially spaced grooves, one groove having a helical edge and serving as a discharge groove and the other having passages leading therefrom tothe inner end face ofthe plunger and space in the sleeve including the internal groove and serving as a fuel pumping chamber, spring means for urging the sleeve and piston outwardly of the body and positioning the sleeve ange in the inner end ofthe body counterbore and the supply ports in register with the plunger grooves to fill the pumping chamber, the spring means opposing inward movement of the sleeve by pressure application on the piston to initially trap and compress the fuel in the pumping chamber and to cause one supply port to register with the body counterbore below the sleeve flange to next cause the internal sleeve groove, discharge port and passages of the sleeve to register with the helical edge of the plunger discharge groove to start discharge of compressed fuel from the pumping chamber and to finally cause the internal groove to register with the inner end of the plunger to end discharge of fuel from and retrap and compress the fuel remaining in the pumping chamber to stop further inward movement of the sleeve and plunger, said spring returning the sleeve and piston and flange on the sleeve to the normal filling position causing trapping of fuel between the ange and body counterbore thereby preventing contact therebetween.

13. In a fuel injection pump, a pump body having a bore and a fuel pressure supply passage opening therein, a sleeve in said bore and having 13 a closed end, an internal groove adjacent the vclosed end serving as part of a fuel pumping chamber, three separate ports and a discharge passage extending through the closed end to one port serving as a fuel discharge port, means securing the sleeve in the body bore so that the other two sleeve ports are placed in communication with the pressure supply passage of the body to serve as fuel supply ports, a plunger in the sleeve having two grooves, one servingas a discharge groove and the other communicating with a passage extending to the end face and pumping chamber, resilient means normally urging 'the plunger outwardly of the chamber to cause registration of the sleeve supply ports with the plunger grooves to cause fuel filling of the ports, grooves and chamber, and means for moving the plunger into the chamber to close the fuel supply ports and trap and compress fuel in the chamber and piston grooves and passages to then causev the plunger discharge groove to register with the sleeve discharge port and internal groove to start discharge of fuel through the discharge passage and to then cause the other plunger groove to register with one of the sleeve supply ports and reduce the pressure' in the pumping chamber. followed immediately thereafter by closure of the internal sleeve groove by the plunger to discontinue fuel discharge and maintain continuous relief of pressure from the pumping chamber.

14. In a fuel injection pump, a pump body having a bore provided with counterbored end portions and a fuel pressure supply opening in the bore, a sleeve reciprocal in the body bore having a closed end piston portion slidable in one end body counterbore, an internal groove adjacent the closed end piston portion and a flange on the other end movable in the other end body counterbore, a sleeve retainer in the open end of the body counterbore in which the sleeve flange is movable, the sleeve also having axially spaced fuel supply ports in continuous communication with the body fuel pressure supply opening, a fuel pressure discharge port and a discharge passage leading therefrom through the piston portion of the sleeve, a plunger rotatably supported in the body and extending into the open end of thsslesveandhavingaxiallyspecedgroons,

14 one groove having a helical edge and servingas a plunger discharge groove and a fuel filling passage leading from the other groove to the inner end of the plunger to the pumping 'space adjacent the sleeve piston portion, spring means urgingthe sleeve and piston outwardly of the body to position the sleeve flange in the inner end of the body counterbore and the supply ports in register with the plunger grooves to flll the pumping chamber with fuel, the spring opposing inward movement of the sleeve by pressure application to the sleeve piston portion to initially trap and compress the fuel in the pumping chamber and to cause one sleeve supply port to register with the body. counterbore and fill it with fuel, to then cause the sleeve discharge port and internal groove to register with the plunger discharge groove to cause discharge of fuel at high pressure outwardly from the pumping chamber through the discharge passage in the sleeve piston portion, to finally cause the internal sleeve groove to be covered by the inner end of the plunger to end fuel discharge and retrap and compress fuel in the pumping chamber to stop further movement of the sleeve, the sleeve flange at this time traps fuel between it and the sleeve retainer to prevent contact therebetween, the spring means in returning the sleeve to the fuel lling position causing the sleeve flange to trap fuel between it and the inner end of the body counterbore to also prevent contact therebetween.

JOHN DICKSON. f KENNETH L: HULBING.

REFERENCES CITED l The following references are of record in the i ille of this patent:

, UNITED STATES PATENTS Number mme om: mmm ma Certificate of Correction Patent No. 2,576,451 November 27, 1951 JOHN DIOKSON ET AL.

It is hereby certified that error appears in the printed specification of thehabove numbered patent requiring correction as follows:

Column 3, line 5, for slot 41 read .slot 5I; column 6, line 22, for the top read the tip; column 14, list of references cited, under FOREIGN PATENTS for Great Britain read Germany;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of March, A. D. 1952.

[SML] THOMAS F. MURPHY,

Assistant ommz'sszoner of Patents.

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