US1944858A

US1944858A - Fuel injection pump

Info

Publication number: US1944858A
Application number: US421513A
Authority: US
Inventors: Baur Ottmar
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch AG; Robert Bosch GmbH
Priority date: 1930-01-17
Filing date: 1930-01-17
Publication date: 1934-01-23
Anticipated expiration: 1951-01-23

Description

Jan. 23, 1934. o. BAUR FUEL INJECTION PUMP Filed Jan. 17, 1930 m. q mvv 1 Q kv N. w QM@ n Md mi s 9m. i m m, AN. Wx AN .U www QN, mx N mw uw mw. o N@ O, l y 9m. QN am S .Q m m m M.. NN. v m l www www H @NEW QN Patented Jan.l 23, 1934 UNITED STATES PATENT crisi-cl3.l

FUEL INJECTION PUMP Ottmar Baur, Stuttgart, Germany, assigner to Robert Bosch Aktiengesellschaft, Stuttgart,

Germany This invention relates to fuel injection pumpsl for internal combustion engines of the Diesel type whereby liquid fuel is injected into the engine cylinder at or near the end of the compression stroke of the engine piston.

In engines of the Diesel type thereis no spark or other similar ignition and ignition occurs the instant the fuel is injected owing to the high temperature of the compressed air in the engine cylinder. Consequently, to produce variations in time of ignition, such as are produced in ordinary internal combustion engines by advancing or retarding the spark, it is necessary to advance or retard the time at which fuel injection com-- mences.

In addition to changing the time of injection of the fuel it is also desirable to be able to vary the amount of fuel delivered to the engine cylinder on each explosion stroke and this variation 20 in amount should be obtainable independently of variations in the time at which fuel injection commences.

One of the principal objects of the present invention is to provide a simple unitary form of fuel pump construction which may be connected or disconnected as a unit, like the ordinary magneto, and which is capable of adjustment both as to the time of injection of fuel and also as to the quantity of fuel supplied per stroke of the pump, the quantity of fuel delivered being accurately measured at all speeds and loads.

Anotherobject of the invention is to provide a fuel pump which is light in weight but which.

will nevertheless be rugged so as to withstand the strains and stresses to which adevice of this kind is subjected. l

Other objects of the invention include reduction in wear of the operating parts, particularly in the means for reciprocating the pump plunger.

One form of construction which has been found to operate very satisfactorily is shown, by way of example, in the accompanying drawing, wherein:

Figure 1 is a vertical, central longitudinal section through the fuel pump.

Figure 2 is a vertical transverse section on the line II-II of Figure 4l, except for certain parts shown in elevation.

The pump comprises a main casing 1 in the lower part 'of which is journaledashaft 2 having cams 3 formed thereon. These cams voperate the plunger pistons 4 by means of tappet rollers 5. The cam shaft is rotated by a clutch member 6 having dogs 7 thereon for engagement with corresponding dogs or recesses in .aclutch member holding valve seat blocks 21 and sleeves 17 in (not shown) on the pump drive shaft of the engine. The first-mentioned clutch memberA 6 is connected to the cam shaft byga coupling, designated as a whole by 8, by means of which the relative' angular positions of the clutch member and 60 shaft'rnay be adjusted whilst rotating to advance or retard the time at which injection of fuel commences.

This coupling is disclosed in greater detail and claimed in the co-pending application filed 55 on even date herewith in my name and in th name of Hermann Lempp. It will, therefore, sunce in the present application to state that the relative angular adjustment is brought about by a sleeve 9 having inwardly extending lugs 10 70 which pass between laterally extending arms 1l on the clutch member 6 and enter longitudinally arranged recesses 12 in the periphery of a bushing 13 mounted on the conical end of the cam shaft. The-sides of the arms 11 and the recesses 12 are formed at an angle to each other, conveniently by making the sides of the arms 11` parallel to the shaft axis while the sides of the recesses l2 are given a slight helical twist. The sleeve 9 is moved longitudinally to and fro by a yoke 14 and a fork 15a mounted on a shaft 15 with its ends in engagement with the yoke. The shaft 15 may be turned 'in any convenient manner, such as by an arm 16.

The pump plungers 4, of which'two are shown since the particular pump illustrated and described herein is adapted for use with a two cylinder engine, are mounted in sleeves 17, supported at their upper ends by the mcasing 1. Around the upper ends of the sleeves 17 are chambers 18 `to which liquid fuel is supplied from a pipe 19. Two oppsitely disposed ports 20 'in each sleeve allow oil to pass through the. latter to or from` the chambers 18. Above the sleeves 17 are valve seat blocks 21 supporting valves 22 pressed thereagainst by springs 23 mounted in valve holder blocks 23a secured by screw threads to the casing,the valve holder blocks thus place. In the operation of the pump the liquid fuel is forced past th'ese valves into the injection or delivery pipes 24, one for each engine cylinder, secured to valve holder blocks 23B. y

The opening and closing of the ports 20 is controlled by the piston plungers. When the top of theplunger is drawn downward so as to uncover the ports 20, fuel in chamber 18 enters the pump cylinder or sleeve 17 as indicated by the arrows in the left-hand of-the two pump cylinders shown. When theplungers are forced up- 110 thereafter fuel is forced past the delivery valves 22. The plungers have a constant fixed stroke so that in order to vary the quantity of fuel delivered per stroke means are provided for varying their effective stroke, that is the distance through which movement of the plunger forces fuel past the delivery Valves. This may be conveniently. accomplished by forming a recess or groove in each plunger extending to their top surfaces so as to be always in free communication with the space above the plunger. This recess has on one side a helically offset margin with respect to the axis of the plunger adapted to allow communication between the recess (and thereby the space above the plunger) and the right-hand port 20. Such communication allows fuel to flow back from the pump cylinder into the chamber 18, as indicated by the arrow in the right-hand of the two pump cylinders shown, instead of being forced past thevalve 22. As this recess margin is helical the point in the stroke of the plunger at which such reverse flow may occur can be varied by turning or rotatably adjusting the plunger about its axis.

.Various means may be used for turning the plunger about its axis. One convenient method is to mount on the plunger a collar 26 having oppositely projecting lugs 27 slidable vertically in slots in the end of a sleeve 28 rotatably mounted on the lower end of the cylinder sleeve 17. The sleeve 28 does not interfere with the reciprocation of the plunger and yet by turning the sleeve the plunger may be turned about its axis into any desired position. The angular position of the sleeves is adjusted by means of a toothed quadrant 29, secured to the upper part of each sleeve, which quadrant meshes with teeth in a rack-bar 30, slidably mounted in the casing 1.

The toothed quadrants 29 may be, and as shown in Fig. 2 are, clamped to the upper part of the sleeves 28, one of the clamps being shown in section to the left of the piston 4 in Fig. 2. This clamping of the quadrants on the upper part of the sleeves 28 enables them to be initially adjusted with respect to the steering edges on the pistons (that is, the helical edges or margins of the recesses in the upper end portions of the pistons shown in Figs. 1 and 2) so that the proper turning movement of the pistons will be effected by the quadrants when operated by the rack bar 30.

The adjustable connection of the toothed quadrants with the plunger pistons, by way of the sleeves 28 which engage the lugs 27 on the plungers and the clamping of the quadrants to those sleeves, is of particular advantage in multi-cylinder pumps, because it enables such an initial setting of all the plunger pistons in their cylinders and of all the quadrants with respect to the pistons that the fuel delivery from all the pump cylinders is maintained uniform throughout the range of variation of quantity delivered.

To enable the adjustments referred to, it is only necessary to remove the cover plate of the pump casing which is shown at the left in Fig. 2 as held by a screw.

The piston plungers are forced upwards, as already explained, by the action of the cams 3 on the rollers 5. This is the direction in which the plungers have to overcome the high pressure needed to force the fuel past the valve 22 and into the engine cylinder against the high pressure therein at the end of the compression stroke.

`'I'he return movement of the piston plungers requires much less force and may be brought about Wards by the cams the ports 20 are closed andV by means of springs 31. The upper ends of these springs bear against dished annular rings 32 which t into recesses in the casing 1. These rings also serve to retain in position the sleeves 28, which pass therethrough, by engaging shoulders on the latter. `The lower ends of these springs bear against washer-like members 33, which surround and engage the upper-sides of the enlarged feet 34 of the plungers and thereby resiliently force the plungers downwardly.

The tappet rollers 5 are mounted on pins 35 supported at each end by the arms of a U-shaped member 36. Surrounding the member 36 is a hardened steel cylinder 37 held in place on the former by the ends of the pins 35 which pass therethrough. This hardened steel cylinder has sliding engagement with the casing 1 and takes the wear produced by lateral thrusts upon the tappet roller and parts connected thereto by the cam. The steel cylinder 37 and the U-shaped member 36 together constitute a housing for the tappet roller, enclosing it on all sides except that presented to the cam.

The tappet rollers are provided with hardened steel rims 38 which are loosely set onto the bodies of the rollers. In spite of the provision of this hardened steel rim wear may occur and the use of a hardened steel rim on the tappetl roller will not avoid wear on the roller. .For these and similar reasons and also to enable initial adjustments to 105 be made the foot of each plunger is arranged to contact the hardened head of a bolt 39 screwed into a central threaded aperture in the U-shaped member 36 of the roller housing. A lock-nut 40 serves to hold this bolt firmly in adjusted position. 110

With the arrangement just described the plunger rod is free to turn about its axis without any turning movement of the roller housing. In fact the ends of the pins 35 project into vertical grooves 4l in the casing 1 for the purpose of enll suring that the axes of the tappet rollers are maintained parallel to the axis of the cam shaft. The end portions of the pins are flattened so as to provide greater contact surfacewiththe sides of such groove.

Lubrication of the plungers is brought about by the liquid fuel itself. Lubrication of tappet rollers and housing therefor is produced by splash lubrication from oil in the lower part or sump of the casing 1. Splash lubrication involves the maintenance of an oil level in the sump between fairly definite limits. For this reason a lubricating oil gauge rod 42 is provided having a threaded head 43, which serves to close the lubricating oil inlet passage, and a long stem as shown in Figure 2. At the bottom of this rod are two marks 44 and 45. The sump is filled to the mark 44 and refilled when the oil level drops to the mark 45.

What is claimed is:

l. A fuel injection pump for internal combustion engines of the Diesel type comprising a cylinder, a piston therein, a rotary driving member, a rotary driven member, means for reciprocating the piston in constant length of stroke by rotation of the said driven member. means for varying the point in the travel of said piston at which fuel delivery from the pump ceases Vwithout varying the length of the piston stroke or the time the delivery stroke and point at which fuel delivery begin, and an angularly adjustable coupling between said driving and driven members for advancing or retarding the time at which the delivery stroke of the piston and fuel delivery by the pump begins.

housing for said roller and a part on said housing in unattached engagement with said piston plunger permitting turning movement of said plunger about its axis relative to said tappet de vice, a hardened steel cylinder forming an annular boundary wall of said housing, a fixed guide having a bore slidably engaging said boundary wall of said housing and oppositely disposed straight-line guideways, a pin mounting said roller within said housing and projecting therethrough to disposal of its' opposite ends in said guideways to maintain the axis of said roller in parallelism with the axis of said cam whereby said cam through said tappet device imparts rectilinear movement to said pump plunger in one direction of its stroke, a spring arranged to press said piston plunger against said tappet device and said tappet device against said cam, means effective by turning said piston plunger on its axis to vary the amount of fuel delivered by said pump, and means for turning said piston on its axis.

3. A multi-cylinder liquid fuel injection pump comprising a plurality of cylinders each having ports for the ow of said fuel into and out of the cylinder and a piston of constant reciprocatory stroke to draw fuel into the cylinder and discharge the same therefrom, one of said ports and the piston of each cylinder being so formed and cooperatively arranged that the point in the piston stroke of beginning the fuel delivery remains constant for all angular positions of the piston, but the quantity of fuel deliveredat each stroke varies with variation of the angular position of said piston in its cylinder, and means -for turning said pistons on their axes to vary their angular positions in their respective cylinders, said means comprising a common operating element and separate mechanisms operated thereby and engaging said pistons to turn the same and adjustable with respect to said pistons for the initial uniform setting of the angular positions of said pistons in said cylinders. y

4. A liquid fuel injection pump comprising a cylinder having ports for the flow of said fuel into and out of said cylinder, a piston in said cylinder of constant reciprocatory stroke to draw fuel into said cylinder and discharge the same therefrom, said piston also being arranged for turning movement about its axis, one of said cylinder ports and said piston being so formed and cooperatively arranged that the point in the pisy ton stroke of beginning the fuel delivery remains constant for all angular positions of the piston, but the quantity of fuel delivered by said pump at each stroke varies with variation of the angular position of said piston in said cylinder from an initial angular position marking the maximum fuel delivery, and means for turning said pistn on its axis to vary its angular position, said means comprising a quadrant turnable about an axis parallel with the axis of said piston, an adjustable connection between said quadrant and said piston whereby the angular position of said piston with respect to its cylinder and said quadrant can be adjustable set, and a rack bar for turning said quadrant.

5. A multi-cylinder liquid fuel injection .pump

comprising a plurality of cylinders each having l stroke to draw fuel intothe cylinder and discharge the same therefrom, one of said ports and the piston of each cylinder being so formed and cooperatively arranged that the point/in the piston stroke of beginning the fuel delivery remains constant for'all angular positions of the piston, but the quantity of fuel delivered at each stroke varies with variation of the angular position of said piston in its cylinder, and means for turning said pistons on their axes to vary their angular positions in their respective cylinders, said means 4comprising aA quadrant for each plstonturnable about an axis paralled with the axis of the piston, an adjustable connection between each quadrant and the corresponding piston whereby the angular positions of said piston :7n their cylinders can be uniformly set, and a common rack bar for turning all of said quadrants.

6. A liquid fuel injection pump comprising a cylinder having an inlet port and a discharge port, a piston plunger slidable in said cylinder and extending outwardly therefrom, said piston being formed and arranged to rst cover said inlet port on its delivery stroke and thereafter uncover said inlet port at diiferent points in its delivery stroke dependent upon the angular position of the piston with respect to the cylinder, a sleeve rotatably mounted on the cylinder, a non-rotatable but slidable connection between said sleeve andplunger, a quadrant removably and adjustably clamped on said sleeve, and a rack bar engaging said quadrant, whereby angular adjustment of said sleeve produces a corresponding change in the angular position of the piston plunger with respect to the cylinder.

7. A multi-cylinder liquid fuel injection pump comprising a plurality of cylinders each having a fuel inlet port and a fuel discharge port, a piston plunger for each cylinder slidable therein and extending outwardly therefrom, said piston being formed and arranged to first cover said inlet port on its delivery stroke and thereafter to uncover said inlet port at different points in its delivery stroke dependent upon the angular position of the piston with respect to the cylinder, and means for uniformly varying the angular positions of the pistons in said cylinders, said means comprising a sleeve for each cylinder rotatably mountedl thereon, a non-rotatable but slidable connection between each saidsleeve and the plunger of the cylinder on which it is mounted, a quadrant on each said sleeve and a common rack bar engaging all of said quadrants, said quadrants being adjustable about said sleeves for the initial uniform setting of the angular positions of said pistons in said cylinders.

8. A fuel injection pump comprising a cylinder, apiston plunger' having one end in said cylinder and the other end projecting therefrom, a cam shaft, a tappet roller mounted to freely engage the came on said shaft, a cup-shaped housing for said roller freely bearing against the projecting end of said plunger, said housing comprising a. hardened steel cylinder, a grooved guide for said housing adapted to contact with the periphery of said steel cylinder, a pin passing through said roller, said housing and into the grooves of said guide operatively to connect the housing and roller and maintain the axis of the rolleriparallel with the axis of rotation gf the cam, and means for turning the piston about its roo through said aperture to form a pump cylinder, a piston in said cylinder and a cam shaft below said piston for operating the same, said housing having apertures in its boundary walls adapted for the insertion therethrough into mounted position of said piston and cam shaft and removable closures for said apertures.

10. A fuel injection pump as in claim 9 in which the removable closure for the cam shaft aperture is provided with a journal bearing for the cam shaft.

11. A fuel injection pump comprising a pump body or` housing as a single casting containing the entire pump mechanism, said housing having an interior apertured partition wall, a bushing mounted through the aperture to form a pump cylinder, a piston in said cylinder and having one end projecting therefrom, a cam shaft spaced from the projecting end of said piston, an apertured partition wall between said cam shaft and said piston, a roller tappet device bearing against a cam on said shaft and extending through theV aperture in said last-mentioned partition wall into unattached engagement with the projecting end of said piston, the aperture in said last-mentioned wall and said tappet device being cooperatively formed to permit bodily reciprocatory movement and prevent bodily rotary movement of said tappet device.

12. A fuel injection device as set forth in claim 11 and in which the apertures in the said two partition walls are in alignment, said housing also having an aperture in an outer boundary wall in alignment with the apertures in said partition walls, said apertures being adapted for the insertion into and mounting within the housing of said piston and tappet device, a side wall of said housing being also provided with an aperture for the insertion into and mounting within the housing of the cam shaft after the piston and tappet device are inserted in place, in the assembly of the parts of said pump.

OTTMAR BAUR.