Fuel Injection Pump For Multi-cylinder Internal Combustion Engines

Abstract

In a fuel injection pump a pump-and-distributor member is axially movably and rotatably disposed between two axially parallel compression springs which are spaced apart 180.degree. with respect to the pump axis and which, through a common yoke, oppose the pressure strokes of said member. A control sleeve is slidably and rotatably arranged on said pump-and-distributor member for altering the starting moment and the period of injection. The angular and axial displacement of the control sleeve is effected by actuating elements connected to said control sleeve and arranged radially outwardly thereof.

Description

This invention relates to a fuel injection pump particularly for a multi-cylinder internal combustion engine and is of the type that has an axially reciprocating and simultaneously rotating pump-and-distributor member, a cam mechanism causing the axial displacements of the pump-and-distributor member against a return force and at least one control sleeve surrounding the pump-and-distributor member and slidable on the lateral face thereof. For the purpose of altering the beginning and/or the terminal moment of fuel delivery of the fuel injection pump, the control sleeve cooperates with a channel having its terminal opening on the lateral face of the pump-and-distributor member.

In fuel injection pumps of the aforenoted type, such as disclosed, for example, in U. S. Pat. No. 2,813,523, the return force for the pump-and-distributor member is generally supplied by a coil-type compression spring which is arranged beneath the pump-and-distributor member coaxially therewith. In this manner the control sleeve is radially accessible for actuating members. Such a structure, however, results in a relatively large axial dimension of the fuel injection pump.

It is an object of the invention to provide an improved fuel injection pump of the aforenoted type which has a reduced axial dimension permitting nevertheless an easy radial access of the actuating members to the control sleeve.

Briefly stated, according to the invention, the resilient return force is supplied by at least two compression springs which are arranged axially parallel with respect to, and uniformly spaced apart from the pump-and-distributor member, so that the control sleeve is adapted to reciprocate between the two compression springs.

The invention will be better understood, as well as further objects and advantages become more apparent, from the ensuing detailed specification of a preferred, although exemplary, embodiment of the invention taken in conjunction with the drawing wherein:

FIG. 1 is an axial sectional view of the fuel injection pump according to the preferred embodiment;

FIG. 2 is a partial axial sectional view along line II--II of FIG. 1; and

FIG. 3 is a partial sectional view along line III--III of FIG. 2.

Turning now to FIG. 1, in a housing 1 of a fuel injection pump for a multi-cylinder internal combustion engine there journals a drive shaft 2 to which there is keyed a radial cam disc 3. The latter carries as many cams 4 as there are cylinders in the internal combustion engine. The cam track of the cam disc 3 is engaged by rollers 5 which journal on pins 6. The latter, in turn, are supported in a bearing ring 7 which is inserted in the pump housing 1. A pump-and-distributor member 8 carries at its driven end a collar 9 which is coupled with the cam disc 3 by means of a pin 10. On the collar 9 there are disposed, in a stacked relationship, two sliding discs 11 and an upwardly spherical disc 12.

Also referring now to FIG. 2, there is provided a bar-like yoke 13 having a central concave face which is complemental to the convex spherical face of the disc 12 and is in a face-to-face engagement therewith. The yoke 13 is engaged by one end of two coil-type compression springs 14 which, at their other end, are supported, through spring seat discs 16, by a radial face of a pump body 15 which fits into the opening of the pump housing 1. As best seen in FIG. 3, the two springs 14 are spaced apart 180.degree. with respect to the axis of the pump-and-distributor member 8. By means of the aforedescribed structure, the springs 14 exert an axial force on the pump-and-distributor member 8. It is noted that by providing a common yoke 13 for both compression springs 14, manufacturing tolerances in the latter are compensated. In the pump body 15 there are press-fitted two axially parallel guiding pins 17 which project through openings 18 provided in the yoke 13 and thus secure the latter against rotation. It is thus seen that the cam disc 3 is pressed against the rollers 5 under the effect of the springs 14.

The pump-and-distributor member 8 reciprocates and rotates in a cylindrical sleeve 19 which is firmly inserted into the pump body 15. The latter is closed at its external end by a threaded closure 21 which presses a valve seat body 22 against a axial end face of the cylindrical sleeve 19. In the valve seat body 22 there is slidably arranged a valve member 23 which in its closed position is pressed against the valve seat body 22 by means of a spring 24.

The inner chamber 26 defined by the pump housing 1 is filled with low-pressure fuel from a source, not shown. From the chamber 26 there extends a channel 27 which leads to an inlet port 28 passing through the cylindrical sleeve 19. The port 28 cooperates with axially parallel grooves 29 provided in a terminal portion of the pump-and-distributor member 8. The grooves 29 communicate with the pump work chamber 30 which is closed by the pressure valve 22, 23. From the inner cavity defined by the threaded closure 21 and disposed downstream of the pressure valve 22, 23, there extends a channel 31 which is formed in the valve body 22 and in the wall of the cylindrical sleeve 19. The channel 31 merges into a radial channel 32 passing through the cylindrical sleeve 19. The channel 32 cooperates with an annular groove 33 in the pump-and-distributor member 8. From the annular groove 33 there extends in the pump-and-distributor member 8 a distributor groove 34 which cooperates with outlet channels 35 (only one shown). Each output channel 35 is arranged radially in the cylinder sleeve 19 and in an inclined manner in the pump body 15 and merges into an associated outlet opening 36 to which there is coupled an injection conduit (not shown) leading to an injection nozzle (also not shown) of the internal combustion engine. Similarly to the cams 4 of the cam disc 3, the axial grooves 29 and the outlet channels 35 together with the outlet openings 36 are equal in number to the cylinders of the internal combustion engine.

From the pump work chamber 30 there extends, within the pump-and-distributor member 8, an axial channel 38 to two radial channels 39 and 40 which merge into control grooves 41 and 42, respectively. The control grooves 41 and 42 are provided in the lateral face of the pump-and-distributor member 8 and cooperate with radial control bores 37 which, in turn, are formed in a control sleeve 43 which surrounds the pump-and-distributor member 8 and is axially and rotatably slidable thereon. The number of the control bores 37 is equal to the number of the cylinders in the internal combustion engine. The control groove 41 extends helically with respect to the axis of the pump-and-distributor member 8 while the control groove 42 extends parallel thereto.

For the axial displacement of the control sleeve 43 there serves an eccentrically supported radial pin 44 which projects into a transversal groove 45 provided on the control sleeve 43. For the rotary motion of the latter there serves an eccentrically supported radial pin 46 which projects into an axially parallel longitudinal groove 47 provided in the control sleeve 43. The eccentric pins 44 and 46 may be arbitrarily operated by setting shafts 49 and 48, respectively, or by adjusting means (not shown) as a function, for example, of the rpm of the internal combustion engine.

The aforedescribed fuel injection operates in the following manner:

When the internal combustion engine is running, the rotating drive shaft 2 of the fuel injection pump and the rotating cam disc 3 generate an axial reciprocating motion and a simultaneous rotary motion of the pump-and-distributor member 8 which is shown in the figures in its lower dead center position. During this operation the cam disc 3 is maintained in continuous contact with the rollers 5 by the force of the return springs 14. The pump work chamber 30 is charged with fuel entering through the inlet port 28. As the cam disc 3 rotates, first the inlet port 28 is closed. During the subsequent effective pressure stroke of the pump-and-distributor member 8, the fuel is delivered from the pump work chamber 30 through the open pressure valve 22, 23 and the channels 31, 32 into the annular groove 33 and therefrom through the distributor groove 34 into one of the outlet channels 35 and the associated coupling opening 36. Therefrom the fuel is admitted to a fuel injection nozzle of the internal combustion engine.

The beginning and the end of the fuel delivery is determined by the control grooves 42 and 41, respectively. Assuming that the pump-and-distributor member 8 rotates in the direction of the arrow A, the effective pressure stroke begins when the groove 42 leaves the associated control bore 37 and terminates when the groove 41 arrives into alignment therewith.

The duration of injection and thus the quantity of the injected fuel may be varied by an axial displacement of the control sleeve 43, because in this manner the arcuate distance between the grooves 41 and 42 measured at the height of the radial control bores 37 is altered while the moment of injection start remains the same. The control sleeve 43 is axially displaced by rotating the adjusting shaft 49. The beginning moment of the injection may be varied by an angular displacement of the control sleeve 43, because in this manner the relative position between the control bores 37 and the control groove 42 is altered, while the aforenoted arcuate distance between the control grooves 41 and 42 remains the same. The control sleeve 43 is angularly displaced by turning the setting shaft 48.

Turning now to FIG. 3, it is seen that the control sleeve 43 which is movable between the compression springs 14 is easily accessible by the components 44 and 46 arranged radially and necessary for its actuation. By virtue of arranging the control sleeve 43 between the compression springs 14, there is achieved a reduction in the axial dimension of the fuel injection pump.

Instead of a sole control sleeve which serves for independently controlling both the fuel quantities and the starting moment of the fuel injection, there may be provided two control sleeves, one controlling the beginning of the fuel injection while the other controlling the terminal moment thereof.

Claims

That which is claimed is:

1. In a fuel injection pump serving a multi-cylinder internal combustion engine and being of the known type that has (a) a pump-and-distributor member, (b) means for continuously rotating said pump-and-distributor member, (c) means causing said pump-and-distributor member to periodically execute pressure strokes, (d) means continuously exerting an axially directed force on said pump-and-distributor member, said force opposing the displacement thereof in executing said delivery strokes, (e) at least one control sleeve slidably mounted on said pump-and-distributor member, (f) groove means provided on said pump-and-distributor member and cooperating with said control sleeve to control, dependent upon the position of the latter, the fuel injection during each said pressure stroke, the improvement comprising,

A. a plurality of spaced compression springs disposed axially parallel and adjacent said pump-and-distributor member,

B. means connecting said springs to said pump-and-distributor member, said springs constituting said means continuously exerting an axially directed force on said pump-and-distributor member and

C. setting means passing through the space between two adjacent springs and connected to said control sleeve to displace the same.

2. An improvement as defined in claim 1, said springs being two in number and being spaced apart 180.degree. with respect to the axis of said pump-and-distributor member.

3. An improvement as defined in claim 1, said means connecting said springs to said pump-and-distributor member being formed of a sole yoke supporting one end of said springs and including means engaging said pump-and-distributor member.

4. An improvement as defined in claim 3, including a disc means affixed to said pump-and-distributor member and having an annular surface of spherical configuration, said means engaging said pump-and-distributor member and forming part of said yoke including a complemental spherical surface in engagement with said disc means.

5. An improvement as defined in claim 3, including means securing said yoke against rotation.

6. An improvement as defined in claim 5, said lastnamed means being formed of axially parallel fixed guiding pins passing through said yoke.