JPH0571822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a front cam drive device for a fuel injection pump, which includes a circular front cam plate that is rotatably driven. a cam surface running over a plurality of rollers to rotate and reciprocate the pump piston, the rollers being supported on pins oriented radially relative to the front cam plate axis;
The pin is supported with its ends in a roller support ring, the roller support ring having a recess for receiving the rollers and fitted into the casing with its outer circumferential section, the pin being a guide plate is disposed, the guide plate being in contact with a radially outwardly facing end surface of the roller;
On the other hand, it concerns a type in which the end face of the recess of the roller support ring facing the adjacent wall is adapted to the shape of said wall.

Prior Art A front cam drive device of the type described above is disclosed in U.S. Patent No.
3374685, in which a roller support ring has an inner ring and an outer ring and is rotatably fitted into a cylindrical casing, the inner and outer rings being adapted to receive the rollers. Notches are limited. In this case, the pin supporting the roller is supported with both ends on the inner and outer rings of the roller support ring and against radial outward movement on the wall of the cylindrical casing of the injection pump. ing.
That is, the position of the pin is defined geometrically by the wall of the casing surrounding the roller support ring. The pin is provided with a radially outwardly facing guide ring and a floating bush.
The original roller is supported on a floating bush. The rollers and the floating bushes contact a guide ring radially outwardly, the guide ring having a radially outwardly facing end face adapted to the circular peripheral wall surface of the outer ring of the roller support ring.
In order to guarantee an always uniformly large contact surface between the roller and the cam surface of the front cam plate running on this roller, the floating bushing is designed with a spherical outer circumference, so that the roller can pivot. It is. A cam drive constructed in this way, in particular with a cylindrical floating bush, is such that upon high loading of the front cam plate, the pins are moved radially outwards and the cylindrical casing receives the roller retaining ring. It has the disadvantage of penetrating walls. In extreme cases, the wall of the casing can break, and the possibility of rotation of the roller support ring is impaired if the fuel injection pump is driven in one rotational position of the roller support ring for an extended period of time. This impediment to the possibility of rotation occurs in particular when the front cam plate is driven to run on rollers and the roller support ring is substantially stationary.
In such an arrangement, a corrective adjustment movement of the roller support ring is necessary only to adjust the injection start timing. If the cylindrical wall casing breaks, which is unfavorable, the pins become stuck in the damaged wall part during the adjustment movement, and the rotation of the roller retaining ring is prevented.

Problem to be Solved by the Invention It is an object of the invention to prevent the pins supporting the rollers from moving radially outwards so that the corrective adjustment movements of the roller support rings supporting the pins are not impaired. .

Means for Solving the Problems In order to solve the above problems, the present invention has the following features:
A pin is force-transmissively connected to the guide plate in a radially outward direction.

Advantages of the Invention With the arrangement of the invention, the radially outward force component acting on the pin is absorbed by the roller support ring;
Damages in the casing wall are eliminated without being transmitted to the casing wall, and a corrective adjustment movement of the roller support ring is ensured.

Advantageous embodiments of the invention are described in the subclaims.

A pump piston 1 of the distribution type fuel injection pump shown in FIG. 1 is mounted with a foot 2 on a front cam plate 3 and is non-rotatably connected to the front cam plate via a pin 4. Furthermore, the pump piston is connected to a bearing (not shown) fixed to the casing.
The front cam plate is pressed against the front cam plate by a compression spring 5 supported by the foot 2 and the foot 2. The front cam plate has a circular cross section and has a cam surface 6 on its edge facing away from the pump piston 1, with which it contacts the roller 7. The roller 7 is supported on a pin 9 via a floating bush 8.
The pin projects on both sides with a floating bush 8 and is seated with its free end in a U-shaped recess 10. The notches 10 are formed in the end faces of the inner ring 12 and outer ring 14 of the roller support ring 15. The roller support ring also has a circular cross section and is pivotably fitted into the cylinder 16 of the housing of the fuel injection pump using a pivoting device (not shown). The rotation of the roller support ring is carried out for the generally known purpose of adjusting the injection start timing. The pins 9 are oriented in the radial plane parallel to and radially to the front cam plate and are distributed in such a way as to transmit the supporting force produced by the roller 7 symmetrically to the front cam plate. A guide plate 18 is attached to the pin 9 between the end faces of the roller 7 and the floating bush 8 and the inner side of the outer ring 14 of the roller support ring, the guide plate being fitted, for example, by a shrink fit or a press fit. It is connected to the pin by friction.

The guide plate 18, the roller 7 and the floating bush 8 are connected to the inner ring 12 of the roller support ring 15.
It protrudes into a ring-shaped notch 19 formed between the outer ring 14 and the outer ring 14 .

The roller support ring 15 is rotated for adjustment as described above and is essentially stationary and is supported in the axial direction of the pump piston by the support ring 20 at the bottom of the casing, whereas the front The cam plate connects to the drive shaft 22 via the connecting portion 23.
rotated by. A cam ridge on the front cam plate defines the number of pump strokes per revolution of the pump piston. When the front cam plate is moved upwards against the force of the return spring, an impulsive force acts on the rollers 7, which tend to displace the pins 9 outwardly in conjunction with the rotational movement. In an advantageous embodiment of the invention, the guide plate 18
is frictionally connected to the pin, so that the pin 9 rotates via the guide plate 18 along the outer ring 14 of the roller support ring, thus avoiding loads on the cylinder 16 of the housing. The guide plate is shaped such that its outer end surface matches the inner diameter of the outer ring and contacts the inner peripheral surface of the outer ring.

Similarly, in the second embodiment shown in FIG.
Supported within 0. However, in this exemplary embodiment, the floating bush 8a is constructed as an intermediate sleeve which is shrink-fitted onto the pin, on which the roller 7 is mounted. Between the end surface of the intermediate sleeve and the inner peripheral surface of the outer ring 14 is a first
As in the embodiment shown, a guide plate 18 is provided, on which the pin 9 rests together with the intermediate sleeve during radial loading. In this embodiment, therefore, the pin 9 is supported on the roller support ring via the guide plate 18 by means of an intermediate sleeve. The shrink fit of the intermediate sleeve provides a large surface contact with the pin 9, resulting in a secure connection. Alternatively, the pin 9 can have a collar at the same location instead of the shrink-fitted intermediate sleeve, which offers manufacturing and assembly advantages. Advantageously, in this embodiment the pins 9 are constructed symmetrically, so that a correct assembly is possible.

In the embodiment shown in FIG. 3, the pin 9a has a ring-shaped notch 24, into which a retaining ring 25 is fitted. Retaining ring 2
5 extends beyond the outer diameter of the pin 9a and into a notch 26 formed in the outer end of the inner circumference of the floating bush 8ab already mentioned in FIG. In this case, the recess 26 can advantageously be designed as a chamfer of the inner bore. floating bush 8ab
A roller 7 is supported as shown in FIG. The roller 7 and the bush 8ab are radial,
Here too it rotates along a similarly provided guide plate 18, which is rotatably mounted on the pin 9a on the opposite side of the retaining ring. In this embodiment, either the pin 9a rotates along the guide plate 18 together with the retaining ring 25, or the floating bush 8ab rotates along the retaining ring 25. In both cases, the pin 9a is axially directed outward and fixed. It is a disadvantage if the floating bushings are constructed asymmetrically on one side, which can lead to confusion during installation. In order to avoid this drawback, a symmetrically designed bushing has the disadvantage, however, that the bearing surface for a given construction space is very small. These drawbacks are obviated by the construction of the embodiment shown in FIG.
ac is constructed symmetrically and without notches and is shortened by the width of the retaining ring 25. The support surface is therefore somewhat smaller for the non-pinned roller support ring configuration, but in this case a larger support surface is obtained than in the embodiment of FIG. The space requirement on the supporting side of the pin is reduced by the fact that the guide plate 18 has a chamfer where it contacts the stop ring 25. The width of the bushing can therefore only be reduced by approximately half the width of the retaining ring.

In the embodiment shown in FIG. 5, the guide plate, the floating bush 8 and the roller 7 are arranged freely rotatable on the pin 9, in which case the pin 9 is arranged in order to stop the pin 9 against axial displacement. The bearing portion is welded to the roller support ring 15. Such welding is advantageously carried out precisely using an electron beam without significant heat generation.

In the embodiment shown in FIG. 6, instead of welding the pin 9, a ring of wear-resistant material is fitted into the cylindrical wall in contact with the pin, so that the area in which the cylindrical wall contacts the pin 9 It will no longer be damaged or deformed.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, in which FIG. 1 is a sectional view of the first embodiment, FIG. 2 is a sectional view of the second embodiment, and FIG. 3 is a sectional view of the third embodiment. FIG. 4 is a sectional view of the fourth embodiment, FIG. 5 is a sectional view of the fifth embodiment, and FIG. 6 is a sectional view of the sixth embodiment. 1... Pump piston, 2... Foot, 3... Front cam plate, 4... Pin, 5... Compression spring, 6... Cam surface, 7... Roller, 8... Bush, 9... Pin, 10
...Notch, 12...Inner ring, 14...Outer ring, 15...Roller support ring, 16...Cylinder, 18
...Guide plate, 19... Notch, 20... Support ring, 22... Drive shaft, 23... Connection portion, 24... Notch, 25... Stop ring, 26... Notch.

Claims (1)

[Scope of Claims] 1. A front cam drive device for a fuel injection pump, which includes a circular front cam plate 3 that is rotatably driven, and a circular cam surface 6 of the front cam plate is connected to a plurality of rollers 7. The rollers 7 are mounted on pins 9 oriented radially with respect to the front cam plate axis, with the pins at their ends rotating and reciprocating the pump pistons. The roller support ring 15 is mounted in a roller support ring 15 which has a recess 19 for receiving the roller and which is fitted into the casing with its outer circumferential section and has a pin 9.
A guide plate 18 is arranged on the side, the guide plate being in contact with the radially outwardly facing end face of the roller 7 on the one hand and the roller support ring 1 on the other hand.
5, the end face of the recess 19 facing the adjacent wall is adapted to the shape of said wall, in which the pin 9 is force-transmissively connected to the guide plate 18 in a direction radially outwards. A front cam drive device characterized by: 2. The front cam drive device according to claim 1, wherein the guide plate 18 is coupled to the pin by shrink fit or press fit. 3. The intermediate sleeve 8a is firmly inserted into the pin 9, and the roller 7 is supported on the intermediate sleeve.
A front cam drive device according to claim 1, wherein a guide plate (18) is rotatably supported between the roller and the roller support ring. 4. An intermediate sleeve 8ab holding the roller 7 on the pin 9a is rotatably supported, and a retaining ring 25 is disposed in the groove of the pin between the guide plate 18 and the roller 7. The front cam drive device described in Section 1.