Tappet for high-pressure fuel pump

Abstract

The invention relates to a tappet (1) for a high-pressure fuel pump, comprising a housing (2) which accommodates a cam follower roller (4) on the upper annular end face (3) thereof, said cam follower roller running on a bolt (5) which is arranged in a flat section (6) of the housing (2), said flat section extending from the upper annular end face (3) and at a height section over an outer circumferential surface (7) of the housing (2), the housing (2) extends above its lower annular end face (9) by means of a sleeve-like adapter (8), which, on the one hand, rests on its tappet-side open end face (10) against the bowstring-shaped lower end face (11) of the flat part (6) and, on the other hand, forms a pump piston bearing (13) on its closed base (12) facing away from the tappet, the adapter piece (8) has a honeycomb-like cross-section and is provided with two axial steps (14, 15), a concave first axial step (14) with a base (12) and a second axial step (15) which is widened relative thereto and has an open end face (10), the axial steps (14, 15) being connected to one another via an annular platform (16).

Description

Technical Field

[0001] The present invention relates to a tappet for a high-pressure fuel pump. The tappet has a hollow cylindrical housing that accommodates a cam follower roller at its upper annular end face. The cam follower roller runs on a pin that is arranged in diametrically opposite flats of the housing. The flats start from the upper annular end face and extend locally in height on the outer peripheral surface of the housing. The housing is extended above its lower annular end face by means of a sleeve-shaped adapter. The adapter, on the one hand, abuts against the bow-shaped lower end side of the flat via its tappet-side open end, and on the other hand, forms a pump piston support on its closed bottom remote from the tappet. Background Art

[0002] A tappet with a tubular adapter is known from DE 10 2017 124 274 B3. The adapter fills the interior space of the housing as radially as possible and substantially. The adapter has a folded flange at its upper end. The adapter is pressed against the inner peripheral surface of the housing via the outer peripheral surface of the flange. Summary of the Invention

[0003] The object is to design a tappet with a light structure that is suitable for a large installation spacing between the cam and the pump piston and is constructed with outstanding rigidity.

[0004] According to the present invention, this object is achieved in that the adapter has a honeycomb-shaped cross-section and is provided with at least two axial steps, a first axial step with a recessed bottom and a second axial step that is widened relative thereto and has an open end side. The axial steps are connected to each other via an annular platform. In this case, it is particularly preferred that the adapter has a hexagonal and thus honeycomb-shaped cross-section on the two axial steps.

[0005] The elongated tappet (constructed onto a standard base housing made of, for example, a steel plate) has a particularly robust adapter and thus copes excellently with the very high forces in modern pump operation. During installation, the adapter can be very simply guided through the lower annular end face of the housing and engaged with the lower end side of the flat. In this case, a press fit on the inner peripheral surface of the housing is possible, or a press fit on the inner peripheral surface of the housing is provided.

[0006] Instead of a hexagonal honeycomb structure, for example, a pentagonal or heptagonal shape can also be considered or provided. It can also be considered and provided that the adapter is provided with more than two axial steps. What is important is the tapered convergence of the axial steps.

[0007] The adapter is additionally strengthened by built-in reinforcing ribs. In a further refinement, the reinforcing ribs have an arcuate shape and extend from the longitudinal edges of the adapter. If necessary, the reinforcing ribs can also be arranged offset from the longitudinal edges in the circumferential direction and / or have a straight edge orientation.

[0008] According to another specific design of the present invention, the adapter is provided with one or more perforated portions (holes, windows). This contributes to a lightweight structure and allows media, such as air or oil, to enter.

[0009] Similarly, the upper edge region of the adapter can have one or more material notches, so that the passage of the medium can also be achieved through them.

[0010] As proposed in the specific design of the present invention, the adapter can be manufactured by methods such as precision casting, plastic injection molding, MIM, or 3D printing.

[0011] Although the bottom of the adapter can be directly used to contact the pump piston and can optionally be provided with a coated hard material layer for this purpose. However, it is also proposed to use / fix a separate contact plate made of a particularly wear-resistant material, etc. The adapter can also have such a length that it does not protrude beyond the housing if necessary.

[0012] Instead of the cam follower roller, a sliding surface in the tappet can also be considered. Alternatively, the tappet can also be installed in the valve mechanism of an internal combustion engine. Description of the Drawings

[0013] Regarding the drawings:

[0014] Figure 1 A perspective view of the completed installed tappet is shown;

[0015] Figure 2 A longitudinal sectional view of the tappet, across the cam follower roller of the tappet;

[0016] Figure 3 Shows with respect to Figure 2 A cross-sectional view rotated 90°;

[0017] Figure 4 A perspective view of the tappet, longitudinally partially cut away;

[0018] Figure 5 A longitudinal sectional view of the adapter is shown; and

[0019] Figure 6 A perspective view of the adapter, seen obliquely from below, is shown. Detailed Description of the Invention

[0020] Figures 1 to 4Shows a tappet 1 for a high-pressure fuel pump. The tappet 1 has a hollow cylindrical housing 2 made of a steel plate. The tappet 1 accommodates a cam follower roller 4 at its upper annular end face 3. The cam follower roller runs on a pin 5 via a needle bearing 25. The pin is arranged in diametrically opposite recessed flats 6 of the housing 2. The two flats 6 start from the upper annular end face 3 of the housing 2 and extend approximately to half the height of the housing 2.

[0021] The housing 2 is extended beyond its lower annular end face 9 by means of a sleeve-shaped adapter 8 having a honeycomb-shaped hexagonal cross-section.

[0022] As can be seen in Figures 1 to 4 , the adapter 8 bears in a force-transmitting manner against the bow-shaped (sehnenartigen) lower end side 11 of the aforementioned flat 6 via its tappet-side open end side 10. The bottom 12 of the adapter 8 remote from the tappet is closed and forms a pump piston support 13 on the outside. According to Figure 5 , the pump piston support can also be a separate contact plate 25.

[0023] As Figure 5 , Figure 6 shows, the adapter 8 is provided with two axial steps 14, 15, thereby forming a tapered configuration. The lower first axial step 14 has an integrally connected bottom 12. In contrast, the second axial step 15 connected to it via an annular platform 16 widens and has an open end side 10. Each axial step 14, 15 has a hexagonal cross-section.

[0024] In order to further increase the stiffness of the adapter 8 and the tappet 1, reinforcing ribs 19 are arranged on the inner peripheral surface 17 of the adapter 8. The reinforcing ribs start domed from the inner side 18 of the bottom 12 of the adapter 8 and are integrally connected to the longitudinal edges 20 of the adapter 8. As can be clearly seen from Figure 2 , Figure 4 , the reinforcing ribs 19 have an arcuate shape.

[0025] From Figure 6 it is known that each wall section 23 of the adapter 8 is provided with a perforated portion 24 configured as a hole. Figure 6 It is also shown that the adapter 8 has bowl-shaped material notches 26 on each wall section 23 starting from the end side 10 of the upper axial step 15.

[0026] List of reference numerals

[0027] 1) Tappet

[0028] 2) Housing

[0029] 3) Annular end face

[0030] 4) Cam follower roller

[0031] 5) Pin

[0032] 6) Flat part

[0033] 7) Outer peripheral surface

[0034] 8) Adapter

[0035] 9) Annular end face

[0036] 10) End side

[0037] 11) Lower end side

[0038] 12) Bottom

[0039] 13) Pump piston support part

[0040] 14) Axial step

[0041] 15) Axial step

[0042] 16) Annular platform

[0043] 17) Inner peripheral surface

[0044] 18) Inner side

[0045] 19) Reinforcing rib

[0046] 20) Longitudinal edge

[0047] 21) Internal space

[0048] 22) Center

[0049] 23) Wall segment

[0050] 24) Perforated part

[0051] 25) Needle roller bearing

[0052] 26) Material notch

Claims

1. A tappet (1) for a high-pressure fuel pump, the tappet having a hollow cylindrical housing (2), the housing receiving a cam follower roller (4) at its upper annular end face (3), the cam follower roller running on a bolt (5), the pin being arranged in diametrically opposite flat portions (6) of the housing (2), the flat portions (6) starting from the upper annular end face (3) and extending locally in height on the outer peripheral surface (7) of the housing (2), wherein, The housing (2) is extended beyond its lower annular end face (9) by means of a sleeve-shaped adapter (8), which on the one hand abuts with its tappet-side open end face (10) against the bow-shaped lower end face (11) of the flat part (6), and on the other hand forms a pump piston bearing (13) on its closed bottom (12) remote from the tappet, characterized in that the adapter (8) has a honeycomb-shaped cross-section and is provided with at least two axial steps (14, 15), a recessed first axial step (14) with the bottom (12) and a relatively widened second axial step (15) with the open end face (10), the axial steps (14, 15) being connected to each other via an annular platform (16).

2. The tappet according to claim 1, characterized in that, The adapter (8) has a hexagonal cross-section.

3. The tappet according to claim 1 or 2, characterized in that, On the inner peripheral face (17) of the adapter (8), starting from the inner side (18) of the bottom (12) and extending up to its open end face (10), reinforcing ribs (19) are arranged.

4. The tappet according to claim 3, characterized in that, The reinforcing ribs (19) extend in an arcuate shape from the longitudinal edges (20) of the adapter (8) into its inner space (21) and converge dome-shaped at the center (22) of the inner side (18) of the bottom (12).

5. The tappet according to claim 1 or 2, characterized in that, At least one wall segment (23) of the adapter (8) is provided with a perforation (24).

6. The tappet according to claim 1 or 2, characterized in that The adapter (8) is manufactured by means of precision casting, plastic injection molding, MIM or 3D printing.

7. The tappet according to claim 1 or 2, characterized in that, On the outer side (18) of the bottom (12) of the adapter (8), a separate contact plate (25) is provided as the pump piston bearing (13).

8. The tappet according to claim 1 or 2, characterized in that, Starting from the end face (10) of the widened axial step (15), the adapter (8) has a material notch (26) on at least one of its wall segments (23).

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