Tappet comprising a cam follower roller for a high-pressure fuel pump of a heavy-duty internal combustion engine

Abstract

The invention relates to a tappet (1) for a high-pressure fuel pump of a heavy-duty internal combustion engine, the tappet comprising a housing (2) which, at its upper annular end face (3), accommodates a cam follower roller (4) which runs on a pin (6) that is seated in receptacles (7) of opposing flats (8) of the housing (2), wherein the housing (2), below the flats (8), is traversed by a separate bridge piece (10) which, on one side, with its face (11) facing the upper annular end face (3) of the housing (2), contacts lower beams (12) of the flats (8), and, on the other side, with its face (16) facing the lower annular end face (15) of the housing (2), is retained in the housing (2) by means of a retaining ring (31), wherein the bridge piece (10) bears against the inner surface (14) of the housing (2) in the circumferential region at the flats (8) via two opposing annular segments (18), wherein the housing (2) is intersected, at least at one of the annular segments (18), by a passage (19) for lubricating oil, said passage leading from a reservoir (20) on the outer surface (9) of the housing (2) and opening into a radial bore (21) in the bridge piece (10), said radial bore being intersected, downstream, by at least one axial bore (22) in the bridge piece (10), which axial bore has an outlet (23) at the upper face (11) of the bridge piece (10) in the longitudinal section between the flats (8) of the housing (2), wherein, as viewed in the axial direction of the cam follower roller (4), the outlet (23) is located at a gap (24) between the cam follower roller (4) and an inner wall (25) of the relevant flat (8), in which inner wall (25) a rising channel (26) for the lubricating oil runs in the direction of the bearing (5) in order to conduct said lubricating oil.

Description

[0001] Tappet with a cam follower for a high-pressure fuel pump of a heavy-duty internal combustion engine

[0002] The invention relates to a tappet, in particular for a high-pressure fuel pump of a heavy-duty internal combustion engine, having a hollow cylindrical housing which accommodates a cam follower roller at its upper annular end, which runs via a bearing on a bolt which is seated in receptacles of diametrically opposed, indented flanges of the housing, which flanges are located at the upper annular end and run vertically along the outer casing of the housing, wherein the housing is penetrated axially below the flange by a separate bridge piece, which, with its end facing the upper annular end of the housing, is in contact with the lower beam of the flange, and the bridge piece, with its end facing the lower annular end of the housing, is held from the housing by a retaining ring, and the bridge piece rests with its outer edge against an inner casing of the housing, at least in circumferential sections,wherein a face of the bridge piece facing a lower annular face of the housing has at least an indirect contact surface for a pump piston. A path for the targeted supply of lubricating oil to the bearing is provided in the tappet.

[0003] The term “heavy-duty internal combustion engine” refers to a machine that is used in particular to drive a truck, van, light transporter, agricultural implement, ship, mining or construction equipment, etc.

[0004] DE 10 2013 215 455 A1 (see Figs. 3 and 4) discloses a tappet with a plain-bearing cam follower roller. An axial channel is formed on the inner walls of the flat supporting the pin with the cam follower roller as a path for lubricating oil. This channel originates from an upper annular end of the housing and runs downwards toward the bearing.

[0005] DE 10 2012 210 176 A1 shows a tappet for a high-pressure fuel pump with a separate bridge piece and a plain-bearing cam follower roller. The bridge piece is fixed on one side to the underside of indented flats supporting the roller pin, and on the other side to a retaining ring applied to the inner surface of the housing. In an upper area, the housing's inner wall is provided with a thinner material.

[0006] DE 10 2015 117 364 A1 describes a high-pressure fuel pump with a pump tappet. Figure 5 shows a two-part pump tappet housing with a lubricating oil path running through both housing parts on one side.

[0007] US 10 006 425 B2 discloses a pump tappet with a basket-like bridge piece in the housing. The outer surfaces of the housing and the bridge piece are intersected by two inclined, fluidly connected oil paths toward the bearing.

[0008] DE 10 2018 214 200 A1 describes a pump tappet of a high-pressure fuel pump with two opposing and radially extending lubricant channels in a solid bridge piece, which are supplied by an annular channel in the outer casing of the bridge piece.

[0009] DE 10 2017 204 920 A1 shows a pump tappet for a high-pressure fuel pump with a cam follower roller mounted on a bolt via a sliding bushing. The pump tappet housing is solidly constructed with a one-piece bridge piece. Two opposing lubricating oil paths run diagonally through the bridge piece toward a gap between the cam follower roller and the inner walls of the housing.

[0010] DE 1 526 700 A describes a roller tappet for a fuel injection pump whose solid housing has an insert with a roller pocket. A recess in the housing for the insert is provided in the bottom area with an oil path extending from the outer casing of the housing.

[0011] The task is to propose a tappet with an improved lubricating oil supply and its bearing.

[0012] According to the invention, this object is achieved by the novel features of claim 1.

[0013] Accordingly, the bridge piece rests on the inner shell of the housing in the circumferential area at the flats via two diametrically opposed ring segments of the outer edge of the housing, wherein the housing is cut in at least one of the ring segments by a passage for the lubricating oil, which starts from a reservoir on the outer shell of the housing and opens into a radial bore in the bridge piece, starting from its outer edge, which is cut downstream of at least one axial bore in the bridge piece, which has an outlet at the upper end of the bridge piece in the longitudinal section between the flats of the housing, wherein, viewed in the axial direction of the cam roller, the outlet is located at a gap between the cam roller and an inner wall of the respective flat, in which inner wall a riser channel for the lubricating oil runs for its further transmission towards the bearing, and wherein the passage, the reservoir, the radial bore,The axial bore and the riser channel are components of the path for the lubricating oil. The tappet is intended for use in a high-pressure fuel pump of a heavy-duty internal combustion engine. However, it can also be used in a high-pressure fuel pump of an internal combustion engine of a passenger car or similar vehicle. The bearing should preferably be a needle bearing, with the cam follower roller running on the pin either directly or via an intermediate ring. Alternatively, a needle bearing is considered.

[0014] The measures according to the invention ensure a targeted supply of lubricating oil / cooling oil to the cam follower bearing in the tappet via a "transfer point" between a guide bore for the tappet on the pump or engine side and an outer casing of the tappet housing. The tappet bearing is thus supplied with lubricating oil from the guide, which is then metered and delivered to the bearing via the tappet path with minimal loss.

[0015] The key feature is the at least one radial bore in the bridge section, from which an axial bore branches off downstream. Preferably, two diametrically opposed radial bores are provided in the bridge section, each with at least one axial bore. A completely radial bore is also possible. An area of ​​the outer casing of the housing around its respective passage is specially designed as a reservoir for the lubricating oil. In particular, a flattened portion or an annular groove or even an annular groove segment is considered.

[0016] The two ring segments of the bridge piece form a tight seal against the inner surface of the housing. If necessary, a separate sealant can also be specifically applied in the contact area. The bridge piece can also be designed with its outer edge at least largely cylindrical all the way around. The measures according to the invention can also be taken with a bridge piece that is connected to the housing in one piece. Furthermore, according to the invention, the respective outlet of the axial bore for the lubricating oil in the bridge piece opens into a gap between the cam follower roller and an inner wall of the respective flat. The oil is then passed on via a riser channel in the inner wall towards the bearing. The outlet of the axial bore can, for example, also open slightly like a funnel, resulting in a spray distribution of the lubricating oil. If necessary, the axial bore can also be angled.

[0017] In a more concrete implementation of the invention, it is proposed to design the bridge piece as a simple disc-like plate with at least largely flat ends. The bridge piece can be stamped from sheet steel, for example. However, it can also be manufactured, for example, using a stamping and extrusion process.

[0018] While the plunger can be equipped with a separate anti-twist device on the outer casing of its housing, it is more practical to have this anti-twist device protrude from the bridge piece as a single piece and project through a window in the housing.

[0019] It is also planned to design the outer surface of the housing as a closed circumferential ring immediately adjacent to its upper ring face. This means that the two flat indentations do not begin directly at the upper ring face. This simplifies the finishing of the tappet housing's outer surface using a centerless grinding process.

[0020] About the drawing:

[0021] Figure 1 shows the tappet in a longitudinal section through the cam roller;

[0022] Figure 2 shows a top view of the tappet; • Figure 3 shows a cross section through the tappet at the level of its bridge piece, looking towards the cam roller and

[0023] • Figure 4 shows the plunger in a longitudinal section at a 90° angle compared to Fig.

[0024] 1 rotated view.

[0025] Shown in various sectional views is a tappet 1 for a high-pressure fuel pump of an internal combustion engine.

[0026] The tappet 1 has a hollow cylindrical housing 2 made of sheet steel. With an upper annular face 3, the housing 2 houses a cam follower roller 4. This is positioned, as shown in Fig.

[0027] 1, 4 show, slightly extends beyond the upper annular end 3 and runs on a bolt 6 via a bearing 5 designed as a plain bearing with an intermediate ring 30. The latter is held at the ends in half-shell-like receptacles 7 of diametrically opposed, inwardly displaced flats 8 of the housing 2. The flats 8 are located axially below a closed circumferential ring 29 of the housing 2. The aforementioned circumferential ring 29 is directly connected to the upper annular end 3.

[0028] Axially below the flat 8, the housing 2 is penetrated by a separate bridge piece 10. Upper and lower ends 11, 16 of the bridge piece 10 are flat. The upper end 11 of the bridge piece 10 rests against the lower beams 12 of the flat 8, which run like a bowstring through the housing 2. An end 16 of the bridge piece 10 facing a lower annular end 15 of the housing 2 has a central contact surface 17 for a pump piston.

[0029] Figure 3 shows that the bridge piece 10 is not circumferentially annular on its outer edge. Two diametrically opposed ring segments 18 of its outer edge 13 rest against the inner shell 14 of the housing 2 in the circumferential area near the flats 8. Offset by 90°, two further ring segments 32, 33 rest against the inner shell 14 of the housing 2.

[0030] A path is provided in tappet 1 for the targeted supply of lubricating oil to bearing 5. This path is explained in more detail below:

[0031] The housing 10 has two diametrically opposed passages 19 for the hydraulic oil. These are each fluidically connected to a reservoir 20 formed as a flat on the outer casing 9 of the housing 2 (see Fig. 1, 3). The lubricating oil is supplied to the two reservoirs 20 via a corresponding supply line in an axial guide for the tappet 1. If necessary, only one supply line can be provided, and one of the reservoirs 20 is connected to the other reservoir 20, for example, via an annular groove. Starting from each ring segment 18, the bridge piece 10 has a radial bore 21. This is in the form of a blind bore.

[0032] Each radial bore 21 is intersected by an axial bore 22, the outlet 23 of which is located at the upper end 11 of the bridge piece 10. The outlet 23 of the respective axial bore 22 is positioned at a gap 24 between the cam follower roller 4 and an inner wall 25 of the respective flat 8. A riser channel 26 for the lubricating oil is formed into the respective inner wall 25 to conduct it toward the bearing 5.

[0033] The reservoir 20, the subsequent passage 19, the downstream radial and axial bores 21, 22 and finally the riser channel 26 are components of the path for the targeted supply of lubricating oil to the bearing 5 for the lubricating oil. Additional lubrication and cooling of the bearing 5 can be achieved by dripping oil / oil mist. Finally, it should be mentioned that the bridge piece 10 is a holder made of the

[0034] Housing 2 through a retaining ring 31 (see Fig. 1, 4).

[0035] List of reference numbers ) Tappet ) Housing ) Ring end ) Cam roller ) Bearing ) Bolt ) Mountings ) Flat ) Outer casing 0)Bridge piece 1 )End 2)Lower beam 3)Outer edge 4)Inner casing 5)Ring end 6)End 7)Contact surface 8)Ring segment 9)Passage 0)Reservoir 1 )Radial bore 2)Axial bore 3)Exit 4)Gap 5)Inner wall 6)Rise channel 7)Window 8)Anti-rotation nose )Rotating ring )Intermediate ring)Retaining ring)Ring segment)Ring segment

Claims

Patent claims 1 . Tappet (1), in particular for a high-pressure fuel pump of a heavy-duty internal combustion engine, with a hollow cylindrical housing (2) which, at its upper annular end (3), accommodates a cam follower roller (4), which runs via a bearing (5) on a bolt (6) which is seated in receptacles (7) of diametrically opposed, indented flats (8) of the housing (2), which flats (8) are located at the upper annular end (3) and run in height sections on the outer casing (9) of the housing (2), wherein the housing (2) is penetrated axially below the flats (8) by a separate bridge piece (10), which, on the one hand, with its end face (11) facing the upper annular end (3) of the housing (2) is in contact with the lower beam (12) of the flats (8) and, on the other hand, with its end face (16) facing the lower annular end (15) of the housing (2), forms a holder from the housing (2) through a retaining ring (31 ),wherein this end face (16) has an at least indirect contact surface (17) for a pump piston, wherein the bridge piece (10) bears against the inner casing (14) of the housing (2) in the circumferential region at the flanges (8) via two diametrically opposed ring segments (18) of its outer edge (13), wherein a path for the targeted supply of the bearing (5) with lubricating oil is provided in the tappet (1), wherein for this purpose the housing (2) is intersected in at least one of the ring segments (18) by a passage (19) for the lubricating oil, which passage starts from a reservoir (20) on the outer casing (9) of the housing (2) and opens into a radial bore (21) in the bridge piece (10), starting from its outer edge (13), which is intersected downstream of at least one axial bore (22) in the bridge piece (10), which has an outlet (23) on the upper end face (11) of the bridge piece (10) in the longitudinal section between the flats (8) of the housing (2), wherein, seen in the axial direction of the cam roller (4),the outlet (23) is located at a gap (24) between the cam roller (4) and an inner wall (25) of the respective flat (8), in which inner wall (25) a riser channel (26) for the lubricating oil runs for its further transmission in the direction of the bearing (5) and wherein the passage (19), the reservoir (20), the radial bore (21), the axial bore (22) and the riser channel (26) are components of the path for the lubricating oil.

2. Tappet according to claim 1, wherein the reservoir (20) is present as a flat or annular groove on the outer shell (9) of the housing (2).

3. Tappet according to claim 1, wherein the bridge piece (10) is a disc-like A plate with at least largely flat ends (11, 16), wherein a rotation-preventing nose (28) protrudes in one piece from the outer edge (13) of the bridge piece (10), circumferentially offset from its ring segments (18), and projects through a window (27) of the housing (2).

4. Tappet according to claim 1, wherein a plain bearing is provided as the bearing (5) for the cam follower roller (4) on the bolt (6).

5. Tappet according to claim 1, wherein the outer shell (9) of the housing (2), immediately at its upper annular end (3), is a closed circumferential ring (29), axially below which the two flats (8) follow.

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