Fuel injection pump

Nov. 27, 1951

J. DICKSON ET AL

FUEL INJECTION PUMP

2,576,451

Filed March 17, 1943

<img file="US2576451A_D0001.tif" />

Patented Nov. 27,1951

2,576,451

UNITED STATES PATENT OFFICE

2.576451

FUEL INJECTION PUMP

John Dickson, Huntington Woods, and Kenneth

L. Hulsing, Plymouth, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware

Application March 17,1948, Serial No. 15,458

Claims.

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 fuelfilling, fuel compression and pressure discharge strokes and providing on the discharge stroke, by-pass from, trapping and compression of the fuel In 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 fluid 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 fluid tight relation in a fuel pressure supply cavity 7 in a cylinder head 9 of an internal combustion engine, by means of gaskets 10—11 between the body and engine cylinder head so that the body counterbore 5 opens into the engine combustion chamber adjacent the inner surface of the cylinder head.

A hollow cylindrical sleeve 13 having an external packing ring 14 is reciprocal in the body bore 3 and is provided with an external flange IS shown In sliding contact with a smaller diameter inner end portion 17 of the counterbore

S. A flanged annular closure member 21 having a gasket 23 thereon is seated on an internal (CL 103—41) 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 5 the reciprocal sleeve 13. A clamping head 27 is seated on the outer faces of the body I and closure member 21 to clamp the closure member in fluid tight relation with the body and sleeve and to retain the body in fluid tight relation in 10 the cavity 7 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 27 of the injection pump for clamping it in place as IS shown.

A plunger 30 having a smaller diameter outer end portion 31 is rotatably mounted in an opening in the clamping head 27 coaxial with the bore in the reciprocal sleeve 13 into which the 20 inner smaller diameter end of the plunger 30 projects. A lever 33 is secured to the outer end 31 of the rotatable plunger 30 for adjusting it angularly with respect to the head 27 and bore of the sleeve 13 and to prevent reciprocal move25 ment 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 39 in the clamping head 27. The thrust collar 37 is positioned between ^3U 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 13 and urges it inwardly of the body bore 3 and the exterior flange IS on ³⁰ the plunger 29 is accordingly urged inwardly and slides in the reduced diameter portion 17 of the outer end body counterbore 6.

The inner end of the reciprocal sleeve 13 is closed by a check valve seat member 41 which is ⁴⁰ seated thereon by a fuel discharge nozzle 4? which is clamped thereto by an actuating piston 45 threaded on the outer end of the sleeve 13. The piston 45 is provided with a longitudinal opening coaxial with the body bore 3 and is pro⁴⁰ vided 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 cham₆₀ ber. The piston 45 is provided with external packing rings 47 slidable into the inner end counterbore 5 of the body I when the compression pressure in the engine compression chamber exerts sufficient force on the piston to _6S overcome the force exerted by the spring washers 35 acting on the other end of the reciprocal

2,576,461 sleeve I 3. The piston 45 and sleeve 13 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 Blot 41 in the sleeve 13, as best shown in Figure 2.

The space in the outer end of the bore of the reciprocal sleeve 13 between the inner end face of the reduced diameter portion 29 of the rotatable plunger 30 and the check valve seat 41, generally Indicated at 53, serves as a fuel pumping chamber. The wall of this chamber is formed by longitudinally spaced internal grooves 55—57 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 Gt extending from the fuel pressure supply cavity 7 to the body bore 3. The outer end of the fuel inlet passage is enlarged at 63 and a fuel inlet filter element 65 is located therein. The reciprocal sleeve 13 has a flat 67 formed thereon which is in continuous registration with the fuel inlet body passage 61 for all relative positions of the plunger with respect thereto. A drilled passage in the reciprocal sleeve 13, serving as a combined fuel inlet and by-pass port 69, extends radially from the flat 67 on the sleeve 13 to the interior of the bore therein and another passage spaced longitudinally outwardly from the port 69 and extending diametrically from the flat part way through the sleeve 13 forms a fuel inlet and relief port 71 and a fuel discharge port 72 diametrically opposite the port 71. The rotatable plunger 29 is provided with a combined fuel inlet, by-pass and relief groove 73 of semi-annular form normally registering with the fuel inlet and by-pass port 69. Radial and axial passages 75—77 in the rotatable plunger 29 lead from the plunger groove 73 to the inner end face thereof and therefore to the pumping chamber 57 to permit fuel under pressure to enter and fill this chamber and these plunger passages. The rotatable plunger 29 is also provided with a helical fuel discharge groove 79 normally registering with the inlet and relief port 71 to permit fuel under pressure to also fill this plunger groove. A longitudinal fuel discharge passage 79 extends from the discharge port 72 in the reciprocal sleeve 13 to registering annular grooves 91 formed in the engaging faces of the sleeve i3 and check valve seat 41, from which a discharge passage 93 extends to the center of the outer face of the valve seat. An axial discharge passage 85 is formed in the nozzle 43 having a counterbore 86 adjacent the inner end face and containing a check valve disk 87 provided with peripheral grooves for establishing communication between the discharge passage of the nozzle and the discharge opening 83 in the seat 41 when the disk 87 is spaced from the seat 41. Fuel spray discharge openings 89 extend radially and axially outwardly from the nozzle passage 85 through the tip of the nozzle which projects through the piston 45 and into the engine combustion chamber.

With the pump sleeve 13 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 7 in the engine cylinder head as described above, the following events occur upon inward movement of the piston 45 and sleeve 13 on the discharge stroke relative to the pump body I and plunger 36 rotatable therein when the engine compression pressure applied to the piston is sufficient to overcome the force of the spring washers 35.

Initial movement of the p.ston 45 and sleeve 13 on the fuel discharge stroke causes the external flange 15 on the sleeve to move out of the smaller diameter portion 17 of the body counterbore 6 and causes displacement and by-pass of fuel out of the pumping chamber 53 through the passages 75—77 and groove 73 In the rotatable plunger and port 69 in the reciprocal sleeve 13 until this port moves out of register with the groove 73 to trap and compress the fuel in the pumping chamber 63 and into register with the bottom of the bottom edge of the small diameter portion 17 of counterbore 9 in the body to allow fuel supply pressure to enter this counterbore. The inlet and relief port 71 in the sleeve simultaneously moves out of register with the helical groove 78 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 13 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 78 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 13. After a predetermined travel the discharge port 72 in the reciprocal sleeve 13 then registers with the helical discharge groove 78 of the rotatable plunger to start discharge of the compressed fuel from the pumping chamber 53 through the helical discharge groove 78, discharge port 72 and passages 79—81—83—85 and 89 in the sleeve 13 and plunger 29, valve seat 41 and nozzle *3 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 13 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 grooveportton 57 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 15 of the sleeve is in the inner end counterbore of the flanged closure member 21 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 15 and closure member 21.

It will be evident that varying the longitudinal spacing of the grooves 73—78 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 78 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

3,678,401 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—57 and the land 50 therebetween of the reciprocal sleeve 13 and their widths may be changed to vary the end of injection and control the compression of fuel and 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 101 having an axial bore 103, a sleeve 105 having an external flange 100 seated on one end face of the body by a check valve seat member 107 which is seated on the outer end of the sleeve by a fuel nozzle 100 in seating engagement therewith and having an external flange 109 which is engaged by an internal flange of a hollow cap member 110 threaded on the fuel pump body 101. A plunger III is reciprocal in the sleeve 105 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 113. It will be noted that the sleeve 105 is provided with an internal groove I 15 forming the inner wall portion of the pumping chamber adjacent the outer end of the sleeve bore closed by the check valve seat member 107. The cap 110 is provided with an external conical seating surface I IT 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 28 in Figure 1, to hold the cap 110 seated in the cylinder head opening.

The plunger III is provided with an external flange 118 at the outer end shown positioned between an internal flange of a hollow follower guide 119. slidable in the outer end of the body bore 103, and a follower 121 held in the hollow guide by a pin 123. The hollow guide 119 is provided with a longitudinal slot 125 in which the inner end of a pin 127 secured in an extension of the body (01 projects, to prevent rotation of the follower 121 and guide I IS. A helical compression spring 129 is placed between the body 101 and an external flange 131 of the guide 119 and normally urges the 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 127 in the body contacts the inner end of the guide slot 125. Movement of the plunger 111 inwardly of the body and sleeve on the fuel discharge stroke is accomplished by a suitable engine operated rocker lever 133 having a roller 135 thereon in engagement with the follower 121.

The plunger 111 is provided with a hexagonal portion 137 adjacent the outer end which is slidable in an internal hexagonal portion of a pinion 139 located between a hollow spacer 141 in the inner end of a counterbore of the body and in contact with the outer end of the sleeve 105 and a thrust washer 143 in the outer end of the body counterbore. A rack 145 is reciprocal in a transverse bore in the body and meshes with the pinion for rotating it and the plunger 111 relative to the sleeve 105.

The body 101, cap 110, sleeve 105 and plunger jl I are provided with the following fuel passages, β

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 1*7—140, the latter opening into the space 151 between the cap 110 and sleeve 105. The sleeve 105 is provided with a combined fuel inlet and by-pass port (93 opening into the space 151 and a drilled passage extending diametrically part way through the sleeve forms a combined inlet and relief port IBB opening Into the space 151 and a discharge port 157 diametrically opposite the port 155. A longitudinal discharge passage 159 in the sleeve 105 leads from the discharge port 155 to registering annular grooves 101 in the seated surfaces of the sleeve and check valve seat. A discharge passage 103 extends from the annular grooves 101 to the center of .the outer face of the check valve seat 107 and opens into a counterbored portion IB* of an axial bore 107 in the fuel nozzle 100. Fuel spray openings ISO are provided in the top of the nozzle and these openings extend radially and angularly outwardly from the axial bore 107. A valve disk 171 is located in the counterbored portion 165 of the 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 107.

The plunger 111 is provided with a combined fuel inlet, by-pass and relief groove 173 of semicircular form and radial and axial passages 175—177 leading therefrom to the pumping chamber 113. The plunger groove 173 registers with the combined inlet and by-pass port (53 of the sleeve 105 when the plunger is at the end of the fuel filling stroke to cause filling of the pumping chamber and the above passages with fuel. With the plunger in this position it will be noted that a helical discharge groove 179 provided thereon registers with the combined inlet and relief port 155 of the sleeve to likewise cause fuel filling of this groove.

Initial inward movement of the plunger 111 by the rock lever 133 against the force of the spring 125 causes fuel in the pumping chamber (13 to be by-passed outwardly therefrom through the plunger passages 175—177. plunger groove 173 and sleeve inlet aand by-pass port 153 until this grooye moves out of register with this port and traps fuel in the pumping chamber. The helical plunger groove 179 also moves out of register with the Inlet and relief port 155 of the sleeve 105 at this time and trails fuel in the helical groove. Further inward movement of the plunger ill causes compression and pressure increase of the fuel trapped in the pumping chamber. The helical plunger groove 179 then registers with the internal groove 115 of the sleeve and equalizes the pressure therein with that of the trapped and compressed fuel in the pumping chamber after which the helical groove 175 registers with the discharge port 157 to start discharge of the compressed fuel through this groove and port from the pumping chamber 113 to and through the passages iOS, 151, 153. IBS» 167 in the sleeve 100, seat member 107 and nozzle 167 and outwardly through the fuel spray openings 169 in the nozzle tip into the engine combustion chamber. Discharge of fuel continues until the plunger inlet and relief groove 173 registers momentarily with the sleeve inlet and relief port to relieve the pressure In the pumping chamber and passages 176—177 momentarily as the inner end surface of the plunger Ki immediately there8,676,461 after moves past the sleeve groove I IB and stops further release of pressure from this inner groove portion of the pumping chamber III and to end fuel discharge therefrom, however, relief of pressure from the outer or end bore portion of the pumping chamber continues to relieve the mechanical load on the engine driven rocker lever III.

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 1 and 2. The compression and pressure of fuel trapped in the compression chamber 111 of the pump shown in Figure 3 is determined by the amount of plunger movement after the plunger grooves 111—178 move past the sleeve ports 183—IBS until the plunger discharge port registers with the sleeve discharge port 151 which causes the start of discharge and injection of fuel into the engine combustion chamber. As previously mentioned the width of the plunger grooves 111—111 and longitudinal spacing and also the angular adjustment of the plunger by the rack 145 and pinion I IB 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 115 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 111 actuating the plunger on the discharge stroke. When the plunger is returned on the filling stroke the compression space 111 is filled by entrance of fuel from the space 151 through registration of the combined inlet and discharge sleeve port 151 and the combined inlet and relief plunger groove 111 and connecting passages 175—111 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 III and the plunger inlet and relief groove 111 and connecting passages ITS— in.