Piston for a high-pressure fuel pump of a heavy-duty internal combustion engine

Abstract

Proposed is a plunger (1) for a high-pressure fuel pump of a heavy-duty internal combustion engine, comprising a hollow cylindrical housing (2) which accommodates a cam roller (4) at its upper end (3), which runs on a pressure-oil-lubricated sliding bearing (5) on a bolt (6) which sits in a flange (8) of the housing (2), which below the cam roller (4) is penetrated by a bridge piece (10) integrally connected to its inner shell (9), on the underside (11) of which lies a separate base plate (12) which has a recessed, central pocket (14) at its lower end (13), the bottom (15) of which is provided as a rest for an end face (16) of a pump piston (17) and its wall region (18) as a direct retaining means for a shell section (19) of the pump piston (17),wherein the lower face (13) of the base disk (12) has an annular arrangement (21) extending in front of its edge (20) for a pump piston spring (22) and wherein in an upper face (23) of the base disk (12) abutting the underside (11) of the bridge piece (10) a path (25) for the pressurized oil runs, supplied by a radial passage (24) in the housing (2), which leads to axial passages (27) exiting directly at inner faces (26) of the flax (8) in the bridge piece (10).

Description

[0001] The invention relates to a plunger for a high-pressure fuel pump of a heavy-duty internal combustion engine, with a hollow cylindrical housing which accommodates a cam roller at its upper end, which runs on a bolt via a pressure oil-lubricated sliding bearing, which sits in the flat of the housing, which is penetrated below the cam roller by a bridge piece connected to its inner shell, wherein in the area of ​​the bridge piece a path for the pressure oil runs which is fed by a radial passage in the housing and leads to axial passages emerging directly at the inner ends of the flat.

[0002] The term "heavy-duty internal combustion engine" refers to a machine used in particular to power a truck, van, light transporter, agricultural equipment, ship, mining or construction site equipment, etc.

[0003] German patent DE 20 2024 100 850 U1 discloses a tappet with a pressure-oil-lubricated sliding bearing for its cam roller. The tappet has a bridge piece separately joined to its housing, on the upper side of which lies a cover plate. A path for supplying pressure oil to the sliding bearing of the cam roller is provided between the cover plate and the bridge piece.

[0004] The task is to design a plunger that is simple in construction, can withstand high forces in heavy-duty applications, and is improved in terms of its functionality.

[0005] According to the invention, this problem is solved by the new features of claim 1. Accordingly, the bridge piece is integrally connected to the inner shell of the housing, with a separate base plate located on its underside, which has a recessed, central pocket on its lower face, the bottom of which serves as a resting surface for an end face of a pump piston and its wall region as a direct retaining means for a shell section of the pump piston, wherein the lower face of the base plate has an annular resting surface for a pump piston spring extending in front of its edge, and wherein the path for the pressurized oil, supplied by a radial passage in the housing, runs in an upper face of the base plate abutting the underside of the bridge piece, leading to the axial passages in the bridge piece that emerge directly from the inner faces of the flax.

[0006] Of particular note is the multifunctionality of the base plate, which is attached to the one-piece bridge section and is preferably solid. This base plate incorporates, firstly, the path for supplying the pressurized oil to the axial passages in the bridge section. This path is bounded and sealed on its axial opposite side by the bridge section. Secondly, the underside of the base plate features an annular recess and guide for the end face of a pump piston spring. Furthermore, the underside of the base plate provides a simple mechanism for attaching and supporting / guiding the pump piston belonging to the high-pressure fuel pump via a recess located therein. This allows for a certain degree of angular movement of the pump piston when it is attached. A separate spring retainer connected to the pump piston spring is not necessary.

[0007] According to a further development of the invention, the path for the pressurized oil in the upper surface of the base plate consists, in short, of two concentric annular channels connected by at least one radial channel. The outer annular channel is in fluid communication with the radial passage in the housing. The inner annular channel is intersected orthogonally by the axial passages in the bridge section. Alternatively, the path could also be applied to the underside of the bridge section and be bounded by the base plate.

[0008] According to a further specification of the invention, the base plate is provided with at least one sealing ring on its outer surface and rests against the inner surface of the housing via this ring, thus ensuring a leak-proof path within the housing. Alternatively, the sealing ring can also be located on the inner surface of the housing. The connection between the base plate and the housing is preferably designed such that the base plate is fixed in the housing, for example, during transport of the plunger. A rotationally oriented installation of the base plate is not necessary, which simplifies its assembly.

[0009] A further subclaim relates to a suitable design of the pocket in the base plate for retaining / guiding the pump piston. This pocket is to be designed as a keyhole path and have an off-center insertion opening and a central retaining opening for the pump piston that intersects the insertion opening. It is clear that the pump piston has, for example, an annular groove at its insertion point, through which it is ultimately inserted into the retaining opening for retention purposes. Alternatively, retaining measures using retaining rings, etc., are also possible.

[0010] The pump piston spring can be seated at its end face in a lowered ring step of the ring assembly in the base plate, without a separate spring plate, and thus receive good guidance.

[0011] The cam roller with plain bearing, which may also include an intermediate ring, runs with a very small gap in front of the inner faces of the flanges. Flow channels are formed into the inner faces, through which the pressurized oil exiting the axial passages in the bridge section is guided to the plain bearing. The axial passages can extend completely along the inner wall of the flanges up to the upper face of the housing.

[0012] The plunger can be extruded or manufactured from sheet metal using stamping and bending techniques.

[0013] Regarding the drawing: • Fig. 1 shows the pestle in longitudinal section; • Fig. Figure 2 shows the plunger as above, but rotated by 90°; • Fig. Figure 3 shows in a spatial and partially broken view the housing of the plunger with mounted base plate and pump piston with pump piston spring; • Fig. Figure 4 shows, as a detail, the base disc in a spatial view from above and • Fig. Figure 5 shows the base plate in a spatial view from below.

[0014] The Fig. 1, Fig. Figure 2 shows a plunger 1 that is specifically designed and prepared for use in a high-pressure fuel pump of a heavy-duty internal combustion engine.

[0015] The plunger 1 has a hollow cylindrical, extruded housing 2. At an upper end face 3, the housing 2 contains a cam roller 4, which projects slightly beyond the end face 3. The cam roller 4 runs on a sliding bearing 5 on a bolt 6. At its end, the bolt 6 sits in receptacles 33 (sa Fig. 3) of diametrically opposite flax 8 of the housing 2.

[0016] Axially below the cam roller 4, a one-piece attached bridge piece 10 extends from an inner shell 9 of the housing 2, which is perforated in the middle (see Fig. 3) A separate, solid base plate 12 lies on the underside 11 of the bridge piece 10. This has a recessed, central pocket 14 on its lower face 13 (sa Fig. 5) A base 15 of this serves as a fixture for an end face 16 of a pump piston 17. A wall area 18 of the pocket 14 is provided as a direct retaining means for a jacket section 19 of the pump piston 17 (see following explanations).

[0017] The lower face 13 of the base plate 12 has a ring-shaped recess 21 for a pump piston spring 22, extending in front of its edge 20, which is arranged as a lowered ring step. Fig. 1, Fig. 2 is removable. The edge 20 of the base plate 12 is provided with a sealing ring 32, over which the base plate 12 rests against the inner shell 9 of the housing 2.

[0018] As from Fig. 4 removable, a path 25 runs in an upper face 23 of the base disk 12, fed by a radial passage 24 in the housing 2, for supplying pressurized oil to the sliding bearing 5. The path 25 consists, firstly, of an annular channel 28 in an edge region between an outer shell 29 of the base disk 12 and its upper face 23. From this annular channel 28, two opposing radial channels 30 branch off inwards as further path components. These open into another annular channel 31 as a path component, above which the axial passages 27 in the bridge piece 10 are located.

[0019] The pressurized oil is conveyed from the axial passages 27 to the sliding bearing 5 via axial rise paths 7 in inner faces 26 of the flax 8.

[0020] Fig. Figure 5 shows the design of the wall section 18 of the pocket 14 in the base plate 12 for retaining the pump piston 17. This wall section 18 is designed as a keyhole path and consists of an off-center insertion opening 34 for the pump piston 17, which intersects a central retaining opening 35 for it. The final assembled retaining state of the pump piston 17 is shown in the Fig. 1, Fig. 2 removable. The pump piston 17 rests with its end face 16 on the bottom 15 of the pocket 14 during cam stroke and is guided in this pocket with slight movement. List of reference figures 1 pestle 2 cases 3 Forehead 4 cam roller 5. Plain bearing 6 bolts 7 Axialsteig trail 8 Flat 9 Inner jacket 10 Bridge section 11. Bottom 12 Base plate 13 Lower forehead 14 bags 15 Floor 16 End forehead 17 pump pistons 18 wall area 19 Mantle section 20 Rand 21 Ring system 22 Pump piston spring 23 Upper forehead 24 Radial crossing Path 25 26 Inner forehead 27 Axial passage 28 Ring channel 29 Outer shell 30 Radial canal 31 Ring channel 32 Sealing ring 33 recording 34 Insertion opening 35 Holding opening QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 20 2024 100 850 U1

[0003]

Claims

[1] Piston (1) for a high-pressure fuel pump of a heavy-duty internal combustion engine, comprising a hollow cylindrical housing (2) which accommodates a cam roller (4) at its upper end (3), which runs on a bolt (6) via a pressure oil-lubricated sliding bearing (5) and which sits in a flange (8) of the housing (2), which below the cam roller (4) is penetrated by a bridge piece (10) integrally connected to its inner shell (9), on the underside (11) of which lies a separate base plate (12) which has a recessed, central pocket (14) at its lower end (13), the bottom (15) of which is provided as a resting surface for an end face (16) of a pump piston (17) and the wall region (18) of which is provided as a direct retaining means for a shell section (19) of the pump piston (17),wherein the lower face (13) of the base disk (12) has an annular arrangement (21) extending in front of its edge (20) for a pump piston spring (22) and wherein in an upper face (23) of the base disk (12) abutting the underside (11) of the bridge piece (10) a path (25) for the pressurized oil runs, supplied by a radial passage (24) in the housing (2), which leads to axial passages (27) exiting directly at inner faces (26) of the flax (8) in the bridge piece (10). [2] Piston according to claim 1, wherein the path (25) for the pressure oil in the upper face (23) of the base disk (12) consists of an annular channel (28) connected to the radial passage (24) in the housing (2) in an edge region between an outer shell (29) of the base disk (12) and its upper face (23), from which annular channel (28) at least one radial channel (30) branches off, which leads to a further annular channel (31) in the upper face (23) intersected by the axial passages (27) in the bridge piece (10). [3] Plunger according to claim 1, wherein the bottom disc (12) is seated on the inner shell (9) of the housing (2) via at least one sealing ring (32) applied to its outer shell (29). [4] Piston according to claim 1, wherein the wall area (18) of the pocket (14) in the base disk (12) for retaining the pump piston (17) is provided as a keyhole path. [5] Piston according to claim 1, wherein the ring assembly (21) for the pump piston spring (22) in the lower face (13) of the base disk (12) is a lowered ring step. [6] Piston according to claim 1, wherein in the inner face (26) of each flax (8) an axial rise path (33) for the pressure oil runs in the direction of the sliding bearing (5). [7] Plunger according to claim 1, wherein the housing (2) is either as an extrusion or as a sheet metal forming part. [8] Plunger according to claim 1 or 3, wherein the bottom disk (12) is axially fixed and rotationally unoriented on the inner shell (9) of the housing (2).

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