US2517483A - Fuel injection pump - Google Patents

Description

Aug. 1, 1950 F. HAUT ETAL 2,517,433

' FUEL INJECTION PUMP Filed July 31, 1946 2 Sheets-Sheet 1 1, 1950 F. HAU'I Em 2,517,483

FUEL INJECTION PUMP Filed July 31, 1946 V 2 Sheets-Sheet 2 ,ll 1\L H i 1 Patented Aug. 1, 1950 FUEL INJECTION PUMP Fritz Haut and William Friedlander, London, England, assignors, by mesne assignments, to Mono-Cam Limited, London, England, a company of Great Britain Application July 31, 1946, Serial No. 687,368 In Great Britain May 24, 1945 Section 1, lublic Law 690, August 8, 1946 Patent expires May 24, 1965 The invention relates to fuel injection pumps for internal combustion engines, particularly Diesel engines, and has the main objects to provide a pump which allows accurate dosage of the fuel injected in exactly equal quantities for all cylinders of a multi-cylinder engine, and the accurate timing of the injection.

The fuel injection pump according to the invehtion belongs to the kind in which the individual pumps are arranged substantially parallel to the pump shaft and the individual plungers are open ated by a common front cam, and in whichthe ends of the barrel communicate, on the one hand, with the fuel supply and, on the other hand.

through non-return valves or directly, with the individual injectors of the internal combustion. engine, and is characterized in that a shunt to the suction side of the pump unit is provided for each individual pump by bores in the plunger the openings of which are controlled by sleeves arranged in a common plate member the axial position of which is controllable for the purpose of varying the length of the effective delivery part, of the stroke for all plungers uniformly.

Preferably the sleeves are arranged for individual axial adjustment in and with respect to the common plate member. In order to overcome the problem of concentricity of these sleeves and the barrels, these sleeves are preferably located in oversize holes of the common plate member.

While the above mentioned sleeves are adapted to control the amount of delivery, the timing of the delivery is controlled in a manner not forming part of the invention by means of slide members carrying rollers in contact With the cam surface which slide members are housed in a common member capable of being angularly adjusted with respect to said cam.

The invention is illustrated by way of example in the accompanying drawings of which Fig. 1 is an elevation partly in section, and Fig. 2 shows the difierent characteristic positions of the plungers in a diagrammatic way.

Referring first to Fig. 1 the body of the pump unit is denoted l and the pump shaft 2 is fulcrumed in this body by means of ball bearings such as a radial bearing 3 and a thrust bearing 4. Shaft 2 carries at its inner end the cam 5 which has a single, axial, protrusion 5a.. A cup shaped member 6 is centered in the body .I and 3 Claims. (ci.103 -41) *2 held in position by means of a split ring I and a number of head screws 8 which hold the ring 1 against the body I. The ring I isembedded into a circular groove of the cup shaped member 6.

Slide members 9 are guided in holes of the base of the said cup shaped member, and in each slide member 9 a roller l0, preferably in the shape of a truncated cone, is pivoted so as to engage with its circumference the cam surface 5, 5a.

The lid 5 I of the pump body I is held in a posi: tion concentrical with shaft 2 by means of bolts (not shown) so as to give a liquid-tight fit against the outer face of the bottom of the cup shaped member 6. Pump barrels [2 are located from out side in said lid II on the same pitch circle with, and at positions opposite to, the slide members 9. These barrels are held in position by means of sockets I3 screwed into the lid ll thus pressing the enlarged heads 12a of the barrels into counter-bored recesses. Spring loaded non-return valves M are housed inside the sockets l3 and retained there by means of the adaptors l5.

These non-return valves are each seated against a bore leadin into the end face of the barrels l2. A circular recess [6 around each barrel head [2a is connected, through a duct IT, with the interior of the lid H and, through ducts 18, with the interior of the individual barrel head l2a.

A ring or plate member I9 is slidably arranged in the interior or the lid l I so that it can be shifted in an axial direction by means of an operating rod 20 which is concentric with the shaft 2, at the opposite end of the pump unit.

Both the shaft 2 and the rod 2%), which are movable parts operated from outside, are tightened by means of glands 2a and 20a, respectively.

Sleeves 2! are housed in oversize bores of sockets 22 and are clamped with their flanges 2 la between the end faces of said sockets 22 and a retaining ring 23, both the socket and the ring being screwed, from opposite sides, into the same threaded bore of the plate member ill, on the same pitch circle with, and opposite to, the barrels l2 and the slide members 9.

A plunger 24 is slidablyarranged with a close fit within each ibarrel l2 and corresponding sleeve 2 I. Between the head 24a and the end face of the sleeve 2! there is a coiled spring 25in that forces the head 24a into contact with the cor responding slide member 9. There is a central bore 24b and a cross bore 240 in each plunger 24 the purpose of which will be explained with reference to Fig. 2. Labyrinth grooves 25 are arranged on the circumference of each piston 24.

The body I may be equipped with an integral foot plate (not shown) and may be attached in the vertical position as shown, or in any other convenient position, to the internal combustion engine, A nipple 26 connects the interior of the lid II with the fuel supply, whereas the nipples or adaptors are connected with the injector in the individual cylinders of the internal combustion engine.

The operating rod is connected with what would be called the throttle control in a -carburetter fed engine. The cup shaped meber 5., while being retained in axial relation to the body I as described, can be turned about the central axis of the unit by means of a lever (not shown) which is connected with the timing control of the engine. are wide enough to allow angular adjustment of the member 5 with respect to pistons 24.

The operation of the pump will be explained with reference to Fig. 2in which the movement of the piston isillus tratedinfive diagrams drawn for convenience-of space at right angles to the position of the piston in Fig. 1. Corresponding partsv are denoted, with the same numerals. as in Fig. 1, to which reference willbe also made where necessary.

The lowermost diagram. of Fig. 2shows the piston 24 in. position, corresponding to theroller til bearin on the flat part of the cam surface The inletports it (which are connected through port, if! with the-interior of the lid l i, Fig. l.) are communicating with the interior of the barrel i2, and the non-return valve M is resting onits seat, closing the outlet from barrel l2,- through the adapter 55 (Fig. l).

The second diagram of Fig, 2, corresponds to a position in which the roller lllhas started to ride on the sloping-up portion of the cam 5a. The piston head has already blocked the inlet portsit; while the crossbore E ic is still within the sleeve 2!. Consequently, the plunger forces the liquid against the non-return valve it which is liftedoff its seat when the piston 2 continues its path in the direction of the arrow, i. e. to the leftin Fig; 2, diagrams 2 and 3 from below, and the delivery of fluid begins.

The middle diagram shows the piston 24 in a position when the roller it has still further continued its relative movement along the sloningupportion of cam 5a which in reality is the moving part, being turned by shaft 2. be seen that in this diagram the cross bore Me has just begun to clear the edge of the sleeve 2| thus allowing the liquid to escape from the barrel l2 through the lo-ngitudinalbore Mb'and the said cross bore M0 back into the interior of the lid 8 i. This position thereforemarks the end of the delivery period, and the non-return valve M is again moving towards its seat under the action of its spring.

In the position represented by the second diaphragm from above of Fig. 2 the piston has reached its dead centre position corresponding to the roller it having reached the peak of the cam 5a. There is, however, no delivery on the last stretch of stroke as the interior of. the barrel i2 is in communication with that of the lid H as described above.

'In the uppermost diagram of'Fig. 2 the roller Recesses 9a in the slide members 9 It will II] is assumed to be on the downward slope of cam 5a and the piston head 24a following up the movement of the slide member 9 under the action of the spring between said piston head and the end of sleeve 2|. The piston is just clearing the inlet ports I B, and the cross bore 240 is at the same time disappearing within the sleeve 2!. Consequentlyliquid is sucked from, the interior of the lid H through ports I]; I8 into the barrel l2 on the piston 24 continuing its travel in the direction of the arrow, 1, e. to the right hand side in the diagram under consideration.

Eventually the other dead centre position of the piston, represented in the lowermost diagram of Fig. 2 is reached again, as soon as the roller has reached the flat portion of cam 5.

As the shaft 2 rotates the cam 5a is operating one of the pistons 24 after the other in cyclic succession. It is now clear that by turning the cup shaped member 6 about the central axis the timing of the moments when these operations occur is altered.

By shifting the plate member H! by means of the operating rod 20 the position of the sleeves 2! with respect: to the pistons 2.4. is altered, and consequently the moment of covering and uncovering the cross bore 240. Thus the length of the delivery period of the individual pumps, of the unit is controlled in a uniform manner.

The liquid: forced through the nipples I5, is replaced by liquid supplied through nipple 26 (Fig. 1) which is shownito be of wider inner diameter in order to keep resistance on the suction side as low as possible.

What we claim is:

1. A fuel injection pump for internal combustion engines comprising substantially cylindrical casing having an internal fuel chamber, means for suplying fuel to the chamber, a pluralityof pump barrelsmounted within the casing parallel with the axis thereof and uniformly spaced in a circle about the said axis, each pump barrel communicating at one end with the fuel chamber and at the other end with an individual injector of the internal combustion engine, a pump plunger reciprocably fitted intoeach pump barrel, a drive shaft disposed axially of the casing, a common front cam secured on-the drive shaft, resilient means normally urging the pump plungers outwards of the pump barrels, means operated by the cam for urging the pump plungers inwards of their respective pump-barrels in succession for forcing fuel from the bar rels to the cylinders of the engine, a port for each barrel opening into the space within the'barrel which is swept by the plunger as it reciprocates therein, passages leading from the fuel chamher to the respective ports, an axial bore in each plunger permanently open at one end to the swept space in the respective pump barrel, a transverse bore in each plunger establishing communication between the other end of theaxialbore therein and the surface of the plunger, a sleeve fitted closely on each plunger to determine the point in the stroke thereof at which the-transverse bore in the plunger is placed-in communication with the fuel chamber, a plate member located within the fuel chamber and engaged with all. the said sleeves, and means for varying the position of the plate member axially of the casing in order to adjust the sleeves relativeto the-respective plungers simultaneously and thereby to vary the effective delivery part of the stroke for all plungers uniformly.

2. A fuel injection pump as claimed in claim 1, in which means is provided for axially adjusting the sleeves individually with respect to the plate member with which they are engaged.

3. A fuel injection pump as claimed in claim 1, in which the plate member is formed with apertures of a greater diameter than the sleeves, a

sleeve is accommodated in each aperture, and

means is provided for securing each sleeve in its respective aperture at any one of a number of different positions of axial adjustment relative to the plate member.

FRITZ HAUT.

WILLIAM FRIEDLANDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number

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