Tappet for a high-pressure fuel pump of an internal combustion engine

Abstract

The invention relates to a tappet (1) for a high-pressure fuel pump of an internal combustion engine, having a hollow-cylindrical housing (2) which has, at the drive-side annular end face (3) thereof, a cam roller (6) which runs on a pin (5), the pin (5) being seated in receiving areas (7) of diametrically opposing flat surfaces (8) of the housing (2). An inner casing (9) of the housing (2) is penetrated by a separate bridge piece (14), the lower face (11) of which, said lower face facing an output-side annular end face (10) of the housing (2), has a pump piston support (12), one axial side of the bridge piece (14) resting against lower faces (13) of the flat surface (8) and the other side being fixed on the output side by a securing means (15) extending from the inner casing (9) of the housing (2). The bridge piece (14) is made of two individual elements, a) a force-introducing element (16) which is held on the inner casing (9) of the housing (2), between the lower faces (13) of the flat surface (8) and the securing means (15), and b) a force-discharging element (17) comprising the pump piston support (12) on the lower face (11), the force-discharging element (17) being joined together with an output-side end face (18) of the force-introducing element (16).

Description

[0001] Piston for a high-pressure fuel pump of an internal combustion engine

[0002] The invention relates to a plunger for a high-pressure fuel pump of an internal combustion engine, with a hollow cylindrical housing which, at its drive-side ring end, has a cam roller running on a bolt via a bearing, which bolt sits in receptacles of diametrically opposed, vertically recessed flats of the housing, wherein an inner shell of the housing, axially below the flats, is penetrated by a separate bridge piece, the underside of which, facing an output-side ring end of the housing, has a pump piston assembly, which bridge piece axially abuts on the drive side against the lower ends of the flats and is fixed on the output side by a locking means extending from the inner shell of the housing.

[0003] A plunger of this type is described in DE 102021 116 845 A1. Its bridge piece is a solid beam which runs parallel to the roller pins in the housing and is seated in longitudinal slots extending from the output-side ring face of the housing.

[0004] Another plunger with a solid bridge piece is described in DE 10 2012 211 113 A1. The bridge piece is fixed towards the output-side ring face of the housing by a retaining ring resting against its inner shell, which also clamps the bridge piece without play.

[0005] The task is to create a plunger with a lightweight and rigid bridge piece that is easy to assemble.

[0006] According to the invention, this problem is solved by constructing the bridge piece from at least two separate elements, a) a force introduction element which is held on the inner shell of the housing, between the lower ends of the flax and the securing means, and b) a force dissipation element with the pump piston assembly on the underside, which force dissipation element is joined to an output-side end face of the force introduction element.

[0007] Particularly preferred is a thin-walled disc spanning a transverse area of ​​the housing's interior, preferably a stamped sheet metal part. The force-dissipation element is a separate cuboid or cuboid-like element that runs diametrically across the interior from one surface to the other. The cuboid is preferably a flow-formed, stamped, or machined part. Alternatively, it can be cut from a semi-finished product such as profile wire.

[0008] The bridge piece is preferably constructed from exactly two separate individual parts, which, according to a further development of the invention, are e.g. welded or soldered together, whereby a positive locking connection (pocket, groove or the like) or a snap-fit ​​connection is also possible.

[0009] The proposed bridge section is therefore only solid in the force-transmitting area, which makes a significant contribution to lightweight construction. According to one variant of a further specification of the invention, the cuboid section, acting as a force-dissipating element, is designed to run precisely from flat to flat (sa top) and thus with its end faces clearly spaced from the inner shell of the housing. This helps to save mass.

[0010] The prefabricated bridge piece can be easily joined to the housing via the output-side ring face of the housing, with the disc in front, and installed in the correct orientation. A simple retaining ring is proposed to secure the bridge piece in the output direction. This ring sits in an annular groove in the inner shell of the housing, and the disc of the bridge piece rests against this groove. Alternatively, snap-in tabs or other indentations / projections projecting integrally from the inner shell of the housing are also suitable. According to a further subclaim, the end faces of the cuboid piece are chamfered on their undersides to optimize stiffness and reduce mass.

[0011] It is also proposed that a tab for rotational orientation be projected from one of the outer edges of the disc, attached to the cuboid piece. This tab protrudes into a window in the housing without extending beyond its outer surface, thus facilitating the correct assembly of the bridge piece. The window can also be a longitudinal slot extending from the output-side ring face of the housing, which simultaneously serves as an engagement point for a rotational locking mechanism for the plunger, originating from a pump-side plunger guide.

[0012] The disc is provided with several preferably punched perforations. These allow the passage of lubricating oil. At the same time, the perforations further contribute to lightweight construction and prevent the plunger from "pumping up" during its oscillating movement in operation.

[0013] The cuboid piece can be unhardened or tempered (surface-hardened on one or more sides / through-hardened).

[0014] The plunger is specifically designed for use in a high-pressure fuel pump. It can also be used in a valve or compressor drive.

[0015] Regarding the drawing:

[0016] • Figure 1 shows a longitudinal section through the tappet, across the cam roller;

[0017] • Figure 2 shows a longitudinal section as above, rotated by 90°;

[0018] • Figure 3 shows a bottom view of the pestle and

[0019] Figure 4 shows a top view of the plunger. Figures 1 and 2 show a plunger 1 for a high-pressure fuel pump of an internal combustion engine. The plunger 1 consists of a hollow cylindrical housing 2 made of sheet steel, which could also be manufactured using flow forming techniques.

[0020] In the case of a drive-side ring end 3, shown above, the housing 2 has a cam roller 6. The latter runs on a bearing 4, designed as a sliding bearing with an intermediate ring 28, on a bolt 5. The latter is supported at its end face in shell-like receptacles 7, which are formed in diametrically opposed, vertically recessed sections 8 of the housing 2 (see Fig. 4). Axially, immediately below the drive-side ring end 3, the housing 2 is shown as a ring around its circumference (see Fig. 2).

[0021] Axially below the aforementioned flax 8, the housing 2 is penetrated on its inner shell 9 by a two-part, separate bridge piece 14. This consists on the one hand of a force introduction element 16 designed as a thin-walled disk and on the other hand of a solid cuboid piece attached to it as a force dissipation element 17.

[0022] The disk 16 rests with its drive-side end face 29 against beam-like lower ends 13 of the flax 8 and spans the interior 19 of the housing 2. In the direction of the output-side ring end face 10 of the housing 2, the disk 16 is fixed by a locking element 15. This is designed as a simple retaining ring, which sits in an annular groove 23 of the inner shell 9 of the housing 2 (see Figs. 1-3).

[0023] The aforementioned cuboid section 17 is welded to an output-side end face 18 of the disk 16 (not shown). A lower surface 11 of the cuboid section 17, facing the output-side annular end face 10 of the housing 2, has a central pump piston assembly 12. The end faces 20 of the cuboid section 17 are flush with the outer walls 21 of the flax 8 and thus do not extend radially. Figure 2 shows that the end faces 20 of the cuboid section 17 transition into the lower surface 11 via chamfers 22.

[0024] The housing 2 has, starting from its output-side ring face 10, an axial slot 26 (window 25) for the engagement of an external rotation lock for the plunger.

[0025] 1. As can be seen from Figures 1 and 3, the aforementioned disk 16 has a radially projecting anti-rotation lug 24 that is attached in one piece. This lug projects into the axial slot 26 at its base 30 and does not extend beyond the housing 2.

[0026] The disc 16 has two kidney-shaped perforations 27 opposite each other on the cuboid piece 17 for the passage of oil or air (see Figures 1, 3).

[0027] List of reference numbers) Tappet) Housing) Ring face) Bearing) Bolt) Cam roller) Mount) Flat) Inner shell 0) Ring face 1) Underside 2) Pump piston assembly 3) Lower face 4) Bridge piece 5) Locking element 6) Force introduction element, disc 7) Force dissipation element, cuboid piece 8) End face (output side) 9) Interior 0) End face 1) Outer wall 2) Chamfer 3) Ring groove 4) Anti-rotation lug 5) Window 6) Axial slot 7) Perforation 8) Intermediate ring 9) End face (drive side) 0) Base

Claims

Patent claims 1. A plunger (1) for a high-pressure fuel pump of an internal combustion engine, comprising a hollow cylindrical housing (2) which, at its drive-side annular end (3), has a cam roller (6) running on a bolt (5) via a bearing (4), which bolt (5) sits in receptacles (7) of diametrically opposite, vertically recessed flanges (8) of the housing (2), wherein an inner shell (9) of the housing (2), axially below the flanges (8), is penetrated by a separate bridge piece (14), the underside (11) of which, facing an output-side annular end (10) of the housing (2), has a pump piston assembly (12), which bridge piece (14) abuts axially on the drive side against lower ends (13) of the flanges (8) and is fixed on the output side by a locking element (15) extending from the inner shell (9) of the housing (2), characterized in that that the bridge section (14) is constructed from at least two separate elements,a) a force introduction element (16) which is held on the inner shell (9) of the housing (2), between the lower ends (13) of the flax (8) and the securing means (15), and b) a force dissipation element (17) with the pump piston assembly (12) on the underside (11), which force dissipation element (17) is joined to an output-side end face (18) of the force introduction element (16).

2. Plunger according to claim 1, characterized in that the force introduction element (16) of the bridge piece (14) is a thin-walled disk spanning at least a large extent transversely an interior space (19) of the housing (2), wherein the force discharge element (17) is a cuboid piece that passes diametrically through the interior space (19) from flat (8) to flat (8).

3. Pestle according to claim 2, characterized in that end faces (20) of the cuboid piece (17) are aligned with outer walls (21) of the flax (8) or that end faces (20) of the cuboid piece (17) are nestled against the inner shell (9) of the housing (2) or lie directly in front of it.

4. Pestle according to claim 2, characterized in that end faces (20) of the cuboid piece (17) transition into the underside (11) via chamfers (22).

5. Plunger according to one of claims 2-4, characterized in that the cuboid piece (17) is joined to the disc (16) either by welding or by other means. joined by soldering, gluing or positive locking, wherein in the latter joining method a pocket or window is provided in the output-side end face (18) of the disk (16) in which the cuboid piece (17) is inserted section by section.

6. Plunger according to claim 2, characterized in that the cuboid piece (17) is either a flow-formed, stamped or chipped part or is cut from a profile wire.

7. Plunger according to claim 1, characterized in that the output-side locking means (15) for the bridge piece (14) is a retaining ring which sits in an annular groove (23) of the inner shell (9) of the housing (2).

8. Plunger according to claim 2, characterized in that the disc (16) is held in a window by a radially projecting anti-rotation lug (24). (25) of the housing (2) is inserted.

9. Plunger according to claim 1 or 8, characterized in that the housing (2), starting from its output-side ring face (10), has an axial slot (26) for the engagement / insertion of a rotation lock for the plunger (1), wherein, in the case of the reference to subclaim 8, the axial slot (26) simultaneously represents the window (25) for the engagement of the anti-rotation lug (24) of the disk (16).

10. Plunger according to claim 2, characterized in that the disc (16) is provided with at least one perforation (27) for media passage.

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