JP2758187B2 - Fuel injection pump - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fuel injection pump for an internal combustion engine, comprising a casing and a fuel injection pump arranged in the casing for a plurality of fuel injection points. A metering rotating distributor and at least one piston for pumping the fuel injection quantity to the associated fuel injection point are provided, wherein the piston is driven by a roller thrust rod, It is slidably guided in a guide cylinder in a holding part connected to the casing and is in contact with a cam ring trajectory which causes a reciprocating movement of a roller push rod by a pressing or rolling member via a rolling member. In this case, it relates to a configuration in which the roller push rod is prevented from turning by at least one guide element connected to the holding part.

2. Description of the Related Art In a fuel injection pump of the above-mentioned type, which is known from DE-OS 34 1982, the fuel injection pump is embodied as a radial piston type dispensing pump, in which case one roller tap is required for each piston. . This roller push rod, which acts as a transmission member for transmitting the lifting movement generated by the cam ring to the piston, transmits only the axially acting force and preferably does not rotate. As the rotation preventing means, a solution configured based on the groove / key principle is used, but this solution requires a high processing cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive means for preventing rotation between a roller push rod and a piston holder.

In order to solve this problem, according to a configuration of the present invention, in a fuel injection pump of the type described at the outset, the roller push rod is formed on its cylindrical peripheral surface by a flat surface. A chamfer, by means of which the roller pusher forms a positive connection with the flat surface of the guide element, wherein the guide element is configured as a pluggable element in the holding part. I have.

Effect of the Invention In the fuel injection pump according to the present invention configured as described above, the rotation preventing means between the roller push rod and the piston holder is based on a simple geometric shape. It has the advantage of being significantly simplified.

As a result, the construction of the piston holder is simplified, whereby the manufacture and assembly of the piston drive element is much simpler than in the prior art.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

A rotating distributor 2 is arranged in the casing 1 of the radial piston fuel injection pump of the distribution type, and is arranged in a bearing which is positioned radially with respect to the distributor and is fixed in position. Fuel under pressure is supplied by a plurality of guided pistons. In the drawing, only one piston 3 is shown by way of example. The distributor 2 is provided with an annular groove 4 in the plane of movement of the piston 3. The annular groove 4 is connected to a pump working chamber 5 whose volume is periodically changed by an axially moving piston 3. The piston 3 is provided with a bore 6 extending radially with respect to the distributor 2 in a fixed piston holder 7.
In addition, it is slidably supported.

In a region of the piston 3 opposite to the pump working chamber 5, a spring support 9 bent in a crank shape is formed in the annular groove 8.
Are engaged. A piston return spring 10 acts on the bottom of the spring receiver, and the other end of the piston return spring is supported by an annular groove 11 of the piston holder 7. Provided is a pot-shaped roller thrust rod 12 which concentrically surrounds the piston return spring 10 and which also engages with the annular groove 11 on the cylindrical peripheral surface, the roller thrust rod 12 having a spring on its inner bottom surface. The bottom of the receiver 9 forms a support surface for supporting the side opposite to the piston return spring 10.

The bottom surface outside the roller push rod 12 is the piston return spring 10
Is connected to the roller 13 by the force of
Are supported by a cam ring 19 driven synchronously with the distributor 2. The cam facing inward of the cam ring 19 causes the piston 3 to carry out a stroke movement which is directed straight against the deflection of the piston return spring 10 and reduces the pump working chamber 5.

The guiding of the roller rod 12 for transmitting the stroke movement takes place in a guide cylinder 14 on the outer peripheral surface of the roller rod, which is coaxial with the bore 6 of the holding part 15;
Numeral 15 is fixedly arranged like the piston holder 7. In order to prevent rotation of the roller push rod during sliding, a cylindrical notch 16 of the holding portion 15 which is cut out in the guide cylinder and is coaxial with the distributor axis.
Has a guide member 17 mounted thereon, the flat end face of which is oriented in the radial plane of the distributor axis and which is oriented towards the roller pusher rod 12, is provided with a roller pusher rod 12.
The outer cylindrical peripheral surface is formably connected to a chamfer 18 formed by a flat surface so as to allow the axial movement of the roller push rod 12 with a play of movement.
The chamfer 18 and the guide member 17 are provided so that the roller push bar 12 can perform its movement without being obstructed.
In the embodiment shown in FIG. 1, the guide member 17 is configured as an expanding ring. Alternatively, the guide member may be a chamfer
Other off-the-shelf standard products that convey shape connections to 18 can also be used. What is common to all these solutions is that the holding part 15 requires only a simple bore 14 for the guiding function for the roller push rod 12 and does not require any other machining steps.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show one embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view of a plunger driving element of a radial piston type distribution pump, and FIG. 2 is a view taken along the line II-II of FIG. FIG. 5 is a diagram illustrating a roller push rod in a cross section. 1 ... casing, 2 ... distribution body, 3 ... piston, 4
... annular groove, 5 ... pump working chamber, 6 ... hole, 7 ... piston holder, 8 ... annular groove, 9 ... spring receiver, 10 ...
Piston return spring, 11 ... Annular groove, 12 ... Roller push rod, 13 ... Roller, 14 ... Guide cylinder, 15 ... Holding part, 16 ... Notch, 17 ... Guide member, 18 ... Chamfer Part, 19 ... cam ring

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jean-Les-Blanc Lyon-Lille-Claude-Fouarreer, France (no address) (56) References JP-A-58-51265 (JP, A) (58) Investigated Field (Int.Cl. ⁶ , DB name) F02M 41/14 350 F02M 41/14 360

Claims (2)

(57) [Claims] 1. A fuel injection pump for an internal combustion engine, comprising a casing (1) and a rotating distributor arranged in the casing for metering the fuel injection quantity for a plurality of fuel injection points. 2) and at least one piston (3) for pumping the fuel injection quantity to the associated fuel injection point, the piston being driven by a roller push rod (12), , The guide cylinder (1) in the holding part (15) connected to the casing (1)
4) It is slidably guided inside and is in contact with the track of the cam ring (19) which causes the reciprocating movement of the roller push rod (12) through the rolling or rotating member by the pressing means. In the case where the roller rod (12) is prevented from turning by at least one guide element (17) connected to the holding part (15), the roller rod (12) has its cylindrical shape. The peripheral surface has a chamfer (18) formed by a flat surface, by means of which the roller pusher (12) forms a positive connection with the flat surface of the guide member (17). In this case, the guide member (17) is configured as a member that can be inserted into the holding portion (15). 2. The fuel injection pump according to claim 1, wherein the guide member is an expanding ring which engages a notch provided in the guide cylinder of the holding portion.