JPH09105369A - Fuel injection pump for internal combusion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the stress of constituent parts so as to prevent damage by providing a groove at an adjusting rod into which a head member disposed at the free end part of a lever arm of an adjusting sleeve is protruded, and providing this groove with an undercut part in a groove base part area on the outside of the support face of the lever arm. SOLUTION: A pump plunger 5 has a controller cutout at its peripheral surface for force-feed quantity adjustment. This cutout 21 is communicated with a pump work chamber 9 through a longitudinal groove 23. An adjusting sleeve 27 is disposed to turn the pump plunger 5, and the adjusting sleeve 27 and the pump plunger 5 are connected through an adjusting arm 29. The adjusting sleeve 27 has a radially protruded lever arm 31, and a head member 33 provided at the free end of the lever arm 31 is engaged into a groove 35 of an adjusting rod 37. The groove 35 is provided with an undercut part in a groove base part area so as to minimize the stress of the engaged part of both members 33, 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump for an internal combustion engine, which is provided with a pump plunger guided in a cylinder hole of a cylinder bush, the pump plunger being driven by a cam drive device. It is adapted to be reciprocally driven in the axial direction, a pump plunger separating the pump working chamber at one end face and coupled for rotation with an adjusting sleeve, the adjusting sleeve being in a radial direction. A lever member having an outwardly directed lever arm, the head member located at the free end of the lever arm projecting into the groove of the adjusting rod.

[0002]

BACKGROUND OF THE INVENTION German Patent Application Publication No. 242
In the case of a fuel injection pump of this type, known from U.S. Pat. No. 1,100,100, a pump plunger is guided in a cylinder bore of a cylinder bush and is driven by a cam drive so as to be axially reciprocable. . This pump plunger has one end face that partitions the pump working chamber in the cylinder bush. A control hole that can be closed and that extends from the low-pressure chamber filled with fuel is opened in the pump working chamber, and a high-pressure injection conduit extends from the pump working chamber. This high-pressure injection conduit is, on the other hand, connected to an injection valve which plunges into the combustion chamber of the internal combustion engine to which fuel is to be supplied.

The pump plunger has a control notch on its outer peripheral surface for adjusting the pumping amount. This control notch is always connected to the pump working chamber and is bounded by a beveled control edge. When the control edge exceeds the control hole provided on the wall of the cylinder hole, the pumping is terminated. By rotating the pump plunger, it is possible to adjust the time when the diagonal control edge and the control hole overlap. For this purpose, the pump plunger is connected for rotation with the adjusting sleeve. A lever arm projecting in the radial direction is arranged on the adjusting sleeve fitted over the pump plunger. The ball head provided at the free end of this lever arm projects into a groove in the adjusting rod which extends at right angles to the axis of the pump plunger. This groove can be shifted from the outside.

However, the known construction of the adjusting rod in the fuel injection pump is damaged, especially at the location of the force transmission between the adjusting rod and the lever arm of the adjusting sleeve, due to stresses in the components and vibration loads. It has the drawback of increasing the risk of

[0005]

SUMMARY OF THE INVENTION The object of the invention is to improve a fuel injection pump of the type mentioned at the outset to eliminate the abovementioned disadvantages, the stresses of the components being significantly reduced and without the risk of damage, which in turn A fuel injection pump provided with an adjusting rod having high durability.

[0006]

In order to solve this problem, in the structure of the present invention, the groove provided in the adjusting rod has an undercut portion in the region of the groove base outside the supporting surface of the lever arm. I was doing it.

[0007]

In the fuel injection pump for an internal combustion engine according to the present invention, since the groove base of the adjusting rod is provided with the undercut portion, the durability of the adjusting rod against breakage can be enhanced. The advantage of such a structural measure for increasing the strength of the adjusting rod is that the new groove geometry according to the invention is integrated into the punching tool, which allows for material and dimensional changes, surface treatments and additional Compared to other heat treatments, there is no cost problem.

This improved groove geometry significantly reduces the stresses on the components of the adjusting rod and thus increases the safety of the adjusting rod against breakage.

The undercut portion provided on the groove base has a cross section larger than the cross section of the groove side surface region, and the transition surface between the groove base and the groove side surface is a curved surface,
Advantageously, it is constructed as an elliptical surface and a surface with a predetermined radius of curvature.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention shown in the drawings will be described.

In the fuel injection pump for an internal combustion engine shown in FIG. 1, a pump plunger 5 is guided in a cylinder hole 1 of a cylinder bush 3. One end face 7 of this pump plunger partitions a pump working chamber 9 in the cylinder bush 3, and this pump plunger is axially reciprocated by a cam drive device 11 acting on an end portion on the side remote from the pump working chamber. Driven movably.

In order to fill the pump working chamber 9 with fuel or to discharge the fuel from the pump working chamber 9, the wall of the cylinder bushing 3 has a control hole 13. This control hole surrounds the cylinder bushing 3 and is a fuel-filled low-pressure chamber 15
Is opened to the pump working chamber 9. Furthermore, a high-pressure injection conduit 17 extends from the pump working chamber 9. This high-pressure injection conduit opens into an injection valve (not shown in detail) that rushes into the combustion chamber of the internal combustion engine to which fuel is to be supplied, and the high-pressure injection conduit has a pressure that is open in the direction of the injection valve. The valve 19 is inserted.

The pump plunger 5 has a control notch 21 on its outer peripheral surface for adjusting the pumping amount. This notch is always connected to the pump working chamber 9 via a longitudinal groove 23, which is bounded in the direction of the pump working chamber 9 by an oblique control edge 25. In the form known from the prior art, this control edge is the control hole 13
When it exceeds, the pressure feeding is terminated. In this case, by rotating the pump plunger 5, it is possible to adjust the time point at which the oblique control edge portion 25 overlaps the control hole 13, and thus the time point at which the pressure feeding ends and the pressure feeding amount can be adjusted.

In order to rotate the pump plunger 5,
An adjusting sleeve 27 is arranged on the pump plunger. The adjusting sleeve and the pump plunger 5 are connected so as to rotate together via a plunger adjusting arm 29 which engages with a corresponding working part of the adjusting sleeve 27. The adjusting sleeve 27 has a lever arm 31 protruding in the radial direction. A ball-shaped head member 33 is arranged at the free end of the lever arm.
The lever arm 31 projects into the groove 35 of the adjusting rod 37 by this head member. This adjusting rod 37 is preferably formed as a profile. In this case, the groove 35 is machined in the horizontal adjustment rod molding material part 39. Such an adjusting rod 37 arranged at a right angle to the axis of the pump plunger 5 is adjustable from the outside in the longitudinal direction of this adjusting rod and has a groove corresponding to the number of pump plungers 5 to be adjusted. 35. These grooves are arranged in rows one behind the other.

In order to improve the strength of the adjusting rod 37, especially in the region of the groove 35, the groove 35 is, as shown enlarged in FIG. 2, outside the support surface of the head member 33 of the lever arm 31, The undercut portion 41 is provided in the region of the groove base.

Such an undercut portion 41 is formed in the groove base of this groove by enlarging the cross section of the groove 35. The straight region 43 of the groove base first transitions into the first radius of curvature 47 via an elliptical region 45, preferably a quarter ellipse. Following this first radius-of-curvature part, a second radius-of-curvature part 49 which is curved in the opposite direction is provided. The second radius of curvature 49 forms the transition to the groove flank. Both radii of curvature 47, 49 can be optimally matched to one another so that the stress at the transition between the groove base of the groove 35 and the groove flanks is minimized.

[Brief description of the drawings]

1 shows a known fuel injection pump with an adjusting rod acting on an adjusting sleeve of a pump plunger.

FIG. 2 is an enlarged view of a part of an adjusting rod with a groove constructed according to the invention, which accommodates the lever arm of the adjusting sleeve.

[Explanation of symbols]

1 cylinder hole, 3 cylinder bush, 5 pump plunger, 7 end face, 9 pump working chamber, 11
Cam drive device, 13 control holes, 15 low pressure chamber,
17 high pressure injection conduit, 19 pressure valve, 21 control notch, 23 longitudinal groove, 25 control edge, 27
Adjustment sleeve, 29 Plunger adjustment arm, 31
Lever arm, 33 head member, 35 groove,
37 adjusting rod, 39 adjusting rod molding material part, 4
1 undercut portion, 43 linear region, 45 elliptical region, 47, 49 radius of curvature portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Karsten Schneider Germany Stuttgart Wolin Strasse 76 (72) Inventor Marx Egger Germany Stuttgart Wunenstein Strasse 58 (72) Inventor Peter Traup Germany Stuttgart Schupemannstraße 26 (72) Inventor Kassim-Merihamchu Stuttgart, Federal Republic of Germany Kaiserslauterer Strasse 48 (72) Inventor Steffen Berns, Stuttgart Am Buberlesbach 17

Claims (6)

[Claims] 1. A fuel injection pump for an internal combustion engine, comprising a pump plunger (5) guided in a cylinder bore (1) of a cylinder bush (3), the pump plunger comprising a cam. It is adapted to be axially reciprocally driven by a drive device (11), the pump plunger separating the pump working chamber (9) by one end face (7), together with the adjusting sleeve (27). A rotationally coupled adjusting sleeve having a radially outwardly directed lever arm (31), the head member (33) being arranged at the free end of the lever arm,
In the type in which it is projected into the groove (35) of the adjusting rod (37), the groove (35) provided in the adjusting rod (37) is provided outside the supporting surface of the lever arm in the area of the groove base. Fuel injection pump for an internal combustion engine, characterized in that it has an undercut portion (41). 2. An undercut portion (41) of the groove (35)
Is arranged outside the guide region of the head member (33) of the lever arm (31) and is formed in the region of the groove base by enlarging the cross section of the groove (35),
2. The fuel injection pump according to claim 1, wherein the transition surface between the groove side surface and the groove base is formed as a curved surface. 3. A linear region (43) of the groove base is first followed by an elliptical region (45), said elliptical region being provided on at least one radius side of the groove by means of a groove side surface. The fuel injection pump of claim 2, wherein the fuel injection pump transitions to the cylindrical wall of. 4. The transition from the elliptical region (45) of the groove (35) to the region of the groove flank is formed by two mutually adjacent radii of curvature (47, 49) which are curved in opposite directions. The fuel injection pump according to claim 3, wherein 5. The elliptical transition region (45) has a quarter
4. The fuel injection pump according to claim 3, which is formed as an ellipse. 6. The fuel injection pump according to claim 1, wherein the head member (33) of the lever arm (31) projecting into the groove (35) of the adjusting rod (37) is formed as a ball.