Tappet for high-pressure fuel pump

Abstract

The invention relates to a tappet (1) for a high-pressure fuel pump, comprising a housing (2), starting from a drive-side ring end face (3) of which two radially recessed and diagonally opposite platforms (4) in which pins (6) carrying cam follower rollers (5) rest, said platforms (4) protruding in a housing-like manner on their undersides (8) facing an output-side ring end face (7) of the tappet (1), wherein a separate bridge (9) penetrates out of the housing (2) axially beneath the cam follower roller (5), the lower end face (10) of the bridge being an abutment for the insertion of the tappet follower, and the upper end face (12) of the bridge being curved on the lower side (8) of the platform (4) in an outer region (13) complementary to the latter and resting on the platform (4) with the outer region (13), wherein the two outer regions (13) of the bridge (9) are each provided with a stress relief notch (14) at the apex.

Description

Technical Field

[0001] The present invention relates to a tappet for a fuel high-pressure pump, the tappet having a housing, two radially recessed and diametrically opposite platforms starting from an annular end face of the driving side of the housing, a pin carrying a cam follower roller being arranged in the two platforms, the platforms being raised in a cover-like manner on the lower side of the annular end face facing the driven side of the tappet, wherein a separate bridge extends axially through the housing below the cam follower roller, the lower end face of the bridge being an abutment portion built into the tappet follower, and the upper end face of the bridge being arched in an arc shape at the lower side of the platform in a complementary manner to the latter in at least an outer region and abutting against the platform through the outer region. Background Art

[0002] This tappet is from EP 2 406 494 B1 Figure 1 The tappet has a separate bridge piece that engages with the housing. The bridge piece has a substantially shell-like geometry and rests with its upper end side outer region against the underside of the platform of the housing. A projection integrally connected to the bridge piece passes through the housing and prevents the tappet from twisting. Summary of the invention

[0003] The aim is to make the aforementioned tappet more resistant to loads.

[0004] According to the invention, this object is achieved in that at least one contact pair, ie the underside of the corresponding platform / the outer region of the bridge, is provided with a stress-relieving notch at the apex.

[0005] For example, corresponding stress-relieving notches pressed into the corresponding outer regions of the bridge and / or cut into the corresponding underside of the platform ensure that the tensile stress points are shifted outwards from the apex (valley) of the curved bridge to the significantly wider contact sections adjoining on both sides at the bridge. Under load, the single-line contact that existed until now is changed into a two-line contact. This leads to a reduction in the maximum stresses and thus achieves a higher load-bearing capacity of the tappet without increasing its mass or significantly changing it.

[0006] In a further development of the invention, measures are proposed for good load transmission to the tappet follower, which can be, for example, a pump piston, an adapter pin, etc. Therefore, the bridge is provided with a projection on its lower end face, which, starting from its upper end face, can be produced simply by deep drawing in the case of a plate-shaped bridge. In addition, the generally hood-like shape of the bridge also allows a cam follower roller to be integrated relatively deeply into the housing or a housing that is axially shorter.

[0007] Although the relief notches on both sides in the upper end face of the bridge can be part of a continuous groove (preferably a variant without a protrusion), it is more convenient that the relief notches are formed only in the edge region of the bridge, thus only in the contact region at the platform.

[0008] The housing and the bridge made of sheet steel contribute to a lightweight structure and reduced manufacturing costs. However, it is also conceivable to produce the housing by flow stamping or cutting or from semi-finished products, such as tube bundles (segmentation).

[0009] The roller tappet according to the invention can also be used in mass or quantity controlled internal combustion engines ( oder In the pump drive outside of a Brennkraftmaschinen) or in a compressor. Instead of a cam, the stroke can also be introduced into the tappet via an eccentric or another periodic stroke generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Regarding the attached pictures:

[0011] Figure 1 Shows an overall stereoscopic view of the tappet and a partially cutaway view of its housing;

[0012] Figure 2 shows a perspective view of a bridge; and

[0013] Figure 3 A detail of the housing in the platform area is shown. DETAILED DESCRIPTION

[0014] Figure 1 A tappet 1 of a high-pressure fuel pump for an internal combustion engine is shown. The tappet 1 is composed of a tubular housing 2 which is composed of sheet steel. The housing 2 surrounds a cam follower roller 5 at the annular end face 3 on the drive side, which protrudes slightly beyond the annular end face 3. The cam follower roller 5 is mounted on a pin 6 in a rolling bearing manner. The pin is accommodated at the end side in a platform 4 of the housing 2 which is recessed in the radial direction and diametrically opposed to each other. The platform 4 is raised in a hood-like manner on its lower side 8 facing the annular end face 7 on the driven side of the tappet 1 (see also FIG. 2 ). Figure 3 ).

[0015] Axially below the cam follower roller, the housing 2 is penetrated by a separate bridge 9 made of sheet steel, which engages with the housing 2 (see also EP 2 406 494 B1). A projection 11 serving as a rotation prevention for the tappet 1 is directed away from the bridge 9 and is guided radially through a recess in the housing 2. The lower end face 10 of the bridge 9 has a contact for the pump piston. Figure 2 As shown, the bridge 9 has a cylindrical projection 15 starting from its upper end face 12 , at which the lower end face 10 for contact with the pump piston is formed.

[0016] like Figure 2 As shown, the bridge 9 has a shell-like shape, wherein the projection 11 extends away from the transverse end face of the shell. The upper end face 12 of the bridge 9 is curved in a complementary manner relative to the lower side 8 of the platform 4 and in the assembled state (see Figure 1 ) is tightly attached to the platform 4 through the outer area 13.

[0017] At the aforementioned outer region 13, the bridge 9 has at its apex (lowest point) a stress-relieving notch 14 introduced without cutting (see Figure 1 , Figure 2 The stress-relief notches each start from an edge 16 of the bridge 9 and end before the central projection 15 .

[0018] Figure 3 An alternative design is disclosed. Here, the stress-relief notches 17 are present in the respective underside 8 of the two platforms 4 and are introduced, for example, by means of a shaped cutout. The stress-relief notches 14 , 17 can also be used in both contact pairs simultaneously.

[0019] Reference numerals list

[0020] 1) Tappet

[0021] 2) Housing

[0022] 3) Ring end face

[0023] 4) Platform

[0024] 5) Cam follower roller

[0025] 6) Pin

[0026] 7) Ring end face

[0027] 8) Lower side

[0028] 9) Bridge

[0029] 10) Lower end surface

[0030] 11) Protrusion

[0031] 12) Upper end surface

[0032] 13) External Area

[0033] 14) Stress unloading notch

[0034] 15) Protrusion

[0035] 16) Edge

[0036] 17) Stress unloading notch

Claims

1. A tappet (1) for a high-pressure fuel pump, the tappet having a housing (2), two radially recessed and diametrically opposite platforms (4) starting from an annular end face (3) on the drive side of the housing, a pin (6) carrying a cam follower roller (5) being arranged in the platforms, the platforms (4) being raised in a shell-like manner on their lower side (8) facing the annular end face (7) on the driven side of the tappet (1), wherein: A separate bridge (9) axially extends out of the housing (2) below the cam follower roller (5), the lower end face (10) of the bridge being an inherent abutment portion for the tappet follower, and the upper end face (12) of the bridge arches in a complementary arc shape with the lower side (8) of the platform (4) at least in an outer region (13) at the lower side (8) of the platform (4) and abuts against the platform (4) with the outer region (13), characterized in that at least one contact pair is provided with a stress relief notch (14, 17) at the apex, the contact pair comprising the corresponding lower side (8) of the platform (4) / the corresponding outer region (13) of the bridge (9).

2. The tappet according to claim 1, characterized in that The bridge (9) has a projection (15) starting from its upper end face (12) to enable the tappet follower to abut against the lower end face (10) of the bridge.

3. The tappet according to claim 2, characterized in that: In case two relief notches (14) are used in the bridge (9), they start from the edge (16) of the bridge and end before the projection (15).

4. The tappet according to claim 1, characterized in that At least one component is made of sheet steel, said component comprising the housing (2) / bridge (9).

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