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

Abstract

Tappet (1) for a high-pressure fuel pump of an internal combustion engine, with a hollow cylindrical housing (2) which has, at its drive-side annular end (3), a cam roller (6) running on a bolt (5) via a bearing (4), which bolt (5) is seated in receptacles (7) of diametrically opposed, height-section-indented flats (8) of the housing (2), wherein an inner casing (9) of the housing (2), axially below the flat (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 system (12), which bridge piece (14) axially bears on the one hand on the drive side against lower ends (13) of the flats (8) and on the other hand is fixed on the output side by a securing means (15) extending from the inner casing (9) of the housing (2), thereby characterized in that the bridge piece (14) is constructed from 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 flat (8) and the securing means (15) and is in the form of a thin-walled disc spanning an interior space (19) of the housing (2) at least largely transversely, and b) a force dissipation element (17) with the pump piston system (12) on the underside (11), which force dissipation element (17) is welded to an output-side end face (18) of the force introduction element (16) and is a cuboid piece which runs diametrically through the interior space (19) from flat (8) to flat (8).

Description

[0001] The invention relates to a tappet for a high-pressure fuel pump of an internal combustion engine, with a hollow cylindrical housing which has a cam roller running on a bolt via a bearing on its drive-side annular end, which bolt is seated in receptacles of diametrically opposed, height-section-indented flats of the housing, wherein an inner jacket of the housing, axially below the flat, is penetrated by a separate bridge piece, the underside of which, facing an output-side annular end of the housing, has a pump piston system, which bridge piece axially rests on the one hand on the drive side against the lower ends of the flats and on the other hand is fixed on the output side by a securing means extending from the inner jacket of the housing.

[0002] A tappet of this type is described in DE 10 2021 116 845 A1. Its bridge piece is a solid beam that runs parallel to the roller pins in the housing and is seated in longitudinal slots extending from the output-side annular face of the housing.

[0003] Another tappet with a solid bridge piece is described in DE 10 2012 211 113 A1. The bridge piece is secured toward the output-side annular face of the housing by a retaining ring on the housing's inner surface, which simultaneously clamps the bridge piece without play.

[0004] The task is to create a tappet with a lightweight and rigid bridge piece that is easy to assemble.

[0005] According to the invention, this object is achieved in that the bridge piece is constructed from two separate elements, a) a force introduction element which is held on the inner shell of the housing, between the lower ends of the flat and the securing means and is present as a thin-walled disc spanning an interior of the housing at least largely transversely and b) a force discharge element with the pump piston system on the underside, which force discharge element is welded to an output-side end face of the force introduction element and is a cuboid piece which runs diametrically through the interior from flat to flat.

[0006] The force introduction element is a thin-walled disc, preferably a stamped sheet metal part, spanning the interior of the housing transversely. The force dissipation element is a separate cuboid or cuboid-like element that runs diametrically across the interior from flat to flat. The cuboid is preferably an extruded, stamped, or chipped part. Alternatively, it can be cut from a semi-finished product such as a profiled wire. The bridge piece is constructed from exactly two separate individual parts that are welded together according to the invention.

[0007] The bridge piece is thus only solid in the force-transmitting area, which represents a significant contribution to lightweight construction. According to a variant of a further refinement of the invention, the cuboid piece, as a force-dissipating element, is designed to run exactly from flat to flat, thus keeping its end faces well spaced from the inner casing of the housing. This helps save mass.

[0008] The prefabricated bridge piece can be easily joined to the housing via the output-side annular face of the housing, with the disc first, and installed in a oriented manner. To secure the bridge piece in the output direction, a simple retaining ring is proposed. This ring sits in an annular groove in the inner casing of the housing and against which the bridge piece's disc rests. Alternatively, snap-on lugs or other indentations / protrusions projecting from the inner casing of the housing are also possible.

[0009] According to a further sub-claim, the end faces of the cuboid piece should be chamfered on the underside to optimize rigidity and reduce mass.

[0010] It is also proposed to have a one-piece projection protruding from an outer edge of the disc to orient the disc with the cuboid piece. The projection projects into a window in the housing without protruding beyond its outer surface, facilitating the correct joining of the bridge piece. The window can also be a longitudinal slot extending from the output-side annular face of the housing, which also serves as an engagement point for a rotation lock for the tappet extending from a pump-side tappet guide.

[0011] 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 tappet from "pumping up" during its oscillating movement during operation.

[0012] The cuboid piece can be unhardened or tempered (surface hardened on one or more sides / through hardened).

[0013] The tappet is specifically designed for a high-pressure fuel pump. It can also be used in a valve train or compressor drive.

[0014] About the drawing: • Fig. 1 shows a longitudinal section through the tappet, across the cam roller; • Fig. 2 shows a longitudinal section as above, rotated by 90 °; • Fig. 3 shows a bottom view of the plunger and • Fig. 4 shows a top view of the plunger.

[0015] From the Fig. 1, Fig. 2 shows a tappet 1 for a high-pressure fuel pump of an internal combustion engine. The tappet 1 consists of a hollow cylindrical housing 2 made of sheet steel, which can also be manufactured by extrusion.

[0016] In the case of a drive-side annular end 3, shown here above, the housing 2 has a cam roller 6. The latter runs on a bolt 5 via a bearing 4 designed as a plain bearing with an intermediate ring 28. The latter is mounted on the end face in shell-like receptacles 7, which are formed in diametrically opposite, height-section-indented flats 8 of the housing 2 (see also Fig. 4). Axially directly below the drive-side annular face 3, the housing 2 is shown in a circumferential ring shape (see Fig. 2).

[0017] Axially below the aforementioned flat 8, the housing 2 is penetrated at 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 disc and, on the other hand, of a solid cuboid piece attached thereto as a force dissipation element 17.

[0018] The disk 16 rests with its drive-side end face 29 against the beam-like lower ends 13 of the flat 8 and spans the interior 19 of the housing 2. In the direction of the output-side annular end face 10 of the housing 2, the disk 16 is secured by a securing means 15. This is designed as a simple retaining ring, which sits in an annular groove 23 of the inner casing 9 of the housing 2 (see Fig. 1 - 3).

[0019] The aforementioned cuboid piece 17 is welded to an output-side end face 18 of the disk 16 (not shown). A bottom side 11 of the cuboid piece 17 facing the output-side annular end face 10 of the housing 2 has a central pump piston system 12. End faces 20 of the cuboid piece 17 are aligned with the outer walls 21 of the plate 8 and thus do not extend radially. Fig. 2, that the end faces 20 of the cuboid piece 17 merge into the underside 11 via bevels 22.

[0020] The housing 2 has, starting from its output-side annular end 10, an axial slot 26 (window 25) for the engagement of an external rotation lock for the tappet 1. As can be seen from the Fig. 1, Fig. 3, the aforementioned disc 16 has a one-piece, radially projecting anti-rotation nose 24. This projects into the axial slot 26 at its base 30 and does not protrude beyond the housing 2.

[0021] 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 Fig. 1, Fig. 3). List of reference numbers 1 pestle 2 housings 3 ring forehead 4 Storage 5 bolts 6 cam roller 7 Recording 8 Flat 9 inner jacket 10 ring forehead 11 Subpage 12 Pump piston system 13 Lower forehead 14 bridge sections 15 securing devices 16 Force introduction element, disc 17 Force transfer element, cuboid piece 18 End face (output side) 19 Interior 20 End forehead 21 Exterior wall 22 Bevel 23 Ring groove 24 Anti-twist tab 25 windows 26 axial slot 27 Perforation 28 intermediate ring 29 Front face (drive side) 30 Reason QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 116 845 A1

[0002] DE 10 2012 211 113 A1

[0003]

Claims

[1] Tappet (1) for a high-pressure fuel pump of an internal combustion engine, with a hollow cylindrical housing (2) which has a cam roller (6) running on a bolt (5) via a bearing (4) at its drive-side annular end (3), which bolt (5) is seated in receptacles (7) of diametrically opposed, vertically indented flats (8) of the housing (2), wherein an inner casing (9) of the housing (2), axially below the flat (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 system (12), which bridge piece (14) axially bears on the one hand on the drive side against lower ends (13) of the flats (8) and on the other hand is fixed on the output side by a securing means (15) extending from the inner casing (9) of the housing (2). is, characterized bythat the bridge piece (14) is constructed from two separate elements, a) a force introduction element (16) which is held on the inner casing (9) of the housing (2), between the lower ends (13) of the flats (8) and the securing means (15) and is in the form of a thin-walled disc spanning at least largely transversely an interior space (19) of the housing (2), and b) a force discharge element (17) with the pump piston system (12) on the underside (11), which force discharge element (17) is welded to an output-side end face (18) of the force introduction element (16) and is a cuboid piece which runs diametrically through the interior space (19) from flat (8) to flat (8). [2] Tappet according to claim 1, characterized by that the end faces (20) of the cuboid piece (17) are aligned with the outer walls (21) of the flat (8) or that the end faces (20) of the cuboid piece (17) are nestled against the inner shell (9) of the housing (2) or are located directly in front of it. [3] Tappet according to claim 1, characterized by that the end faces (20) of the cuboid piece (17) merge into the underside (11) via bevels (22). [4] Tappet according to claim 1, characterized by that the cuboid piece (17) is either in the form of an extruded, punched or chipped part or is cut from a profile wire. [5] Tappet according to claim 1, characterized by that the output-side securing means (15) for the bridge piece (14) is a retaining ring which sits in an annular groove (23) of the inner casing (9) of the housing (2). [6] Tappet according to claim 1, characterized by that the disc (16) is inserted into a window (25) of the housing (2) via a radially projecting anti-rotation nose (24). [7] Tappet according to claim 1, characterized bythat the housing (2), starting from its output-side annular end face (10), has an axial slot (26) for the engagement / reception of a rotation lock for the tappet (1), wherein, in the case of the reference according to dependent claim 8, the axial slot (26) simultaneously represents the window (25) for the engagement of the anti-rotation nose (24) of the disc (16). [8] Tappet according to claim 1, characterized by that the disc (16) is provided with at least one perforation (27) for media passage.

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