Tappet 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, having a housing (2) which receives a cam contact roller (4) that runs on a pin (6) which is seated in receiving areas (7) formed by opposing flat surfaces (8) of the housing (2), wherein a separate bridge piece (10) projects through the housing (2) axially below the flat surfaces (8), the outer edge (13) of said bridge piece (10) resting against the inner casing (14) of the housing (2) at least over a part of the circumference, and a bridge piece (10) lower end (16) which faces a lower ring end (15) of the housing (2) forms a contact surface for a tappet follower. At each flat surface (8), the bridge piece (10) rests against the inner casing (14) of the housing (2) over a ring segment (18) of the outer edge (13) of the bridge piece in the circumferential region. A cover disc (19) lies on an upper end (11) of the bridge piece (10), said cover disc having an upper face (20) which faces away from the bridge piece (10) and on which lower bars (12) of the flat surfaces (8) directly stand. The housing (2) is intersected by a passage (21) for lubricating oil in each of the two ring segments (18) of the bridge piece (10), each passage extending from a reservoir (22) on the outer casing (9) of the housing (2) and opening into a respective radial channel (23) which is formed between the bridge piece (10) and the cover disc (19) and which is intersected downstream by a duct (24) in the cover disc (19), said duct having an outlet (25) in the longitudinal portion between the flat surfaces (8) of the housing (2).

Description

[0001] Tappet 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, with 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 flats of the housing, which flats run in height sections on the outer casing of the housing, wherein the housing is penetrated axially below the flat by a separate bridge piece which is in contact with the lower beam of the flat with its upper end at least indirectly and bears at least partially with its outer edge against an inner casing of the housing, wherein a lower end of the bridge piece facing a lower annular end of the housing forms an at least indirect contact surface for a tappet follower and wherein a path for the targeted supply of the bearing with lubricating oil 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] The task is to propose a tappet as mentioned above with an improved lubricating oil supply and its bearing.According to the invention, this object is achieved in that the bridge piece is nestled against the inner casing of the housing in the circumferential region via a ring segment of its outer edge, wherein a cover plate is located on the upper end of the bridge piece, on the upper side of which, facing away from the bridge piece, the lower beams of the flats are located directly, wherein the housing is cut in at least one of the two ring segments of the bridge piece by a passage for the lubricating oil, which in each case originates from a reservoir on the outer casing of the housing and opens into a respective radial channel formed between the bridge piece and the cover plate, which is cut downstream of at least one passage in the cover plate, which has an outlet in the longitudinal section between the flats of the housing and wherein the reservoir, the passage, the radial channel and the passage are components of the one-sided or two-sided path for the lubricating oil.

[0006] 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 plain bearing, with the cam follower roller running on the pin either directly or via an intermediate ring. Alternatively, a needle bearing is considered. A pump piston or an adapter pin are particularly suitable as the tappet follower.

[0007] Due to the measures according to the invention, a targeted supply of lubricating oil / cooling oil to the bearing of the cam follower in the tappet is achieved via a "transfer point" between a guide bore for the tappet on the pump or internal combustion engine side and an outer casing of the tappet housing. The tappet bearing is thus supplied with lubricating oil from the guide, which lubricating oil is metered and fed to the bearing via the tappet path with little loss. Further lubrication of the bearing can be achieved via lubricating oil dripping in from the upper annular face of the housing. Further preferably, the housing has a passage for the lubricating oil in each of the two annular segments of the bridge piece, and thus a path for lubricating the bearing leads upwards on both sides of the cam follower roller.

[0008] The proposed cover plate is envisioned as a simple stamped sheet metal part joined to the bridge piece. The bridge piece can be formed in the same way. However, it can also be manufactured, for example, using a stamping and extrusion process.

[0009] While it is conceivable and intended to form the radial channel between the bridge piece and the cover plate into the latter, it is more practical to form the radial channel as a continuous channel in the upper side of the bridge piece and, for example, to emboss it there. Alternatively, it is also conceivable to form a short, sack-like channel on each side of the ring segment.

[0010] An area of ​​the housing's outer shell around its respective passage is specially designed as a reservoir for the lubricating oil. This can be a flattened portion, a recess, an annular groove, or even an annular groove segment.

[0011] 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 around its circumference. The measures according to the invention can also be largely implemented with a bridge piece that is integrally connected to the housing. In a further development of the invention, it is provided that the separate bridge piece is designed as a disk-like plate, from whose outer edge, preferably circumferentially offset by 90° to its two ring segments, an anti-rotation lug protrudes. The latter is guided, for example, through an axial slot emanating from the lower annular end of the housing. It should be emphasized that an anti-rotation lug also protrudes from an outer edge of the cover plate; this lug is also guided in the axial slot of the housing, but does not protrude beyond the housing.This eliminates the need for a separate anti-twist measure for the cover plate.

[0012] Alternatively, the cover plate can also be provided without an anti-twist nose and can be held in place, for example, by form-locking elements such as projections and complementary indentations arranged between the cover plate and the bridge piece.

[0013] It is also suggested that the cover plate be either glued, welded, or snapped to the bridge piece. A good seal of the radial channel between the two elements can be achieved by applying a sealant / sealing film or similar material between them.

[0014] In addition, the outer surface of the housing is designed 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.

[0015] About the drawing:

[0016] • Figure 1 shows the plunger in a three-dimensional representation, partially cut away;

[0017] • Figure 2 shows a detail of the cover plate and

[0018] • Figure 3 shows a detail of the bridge piece. Fig. 1 shows a tappet 1 for a high-pressure fuel pump of an internal combustion engine. The tappet 1 has a hollow cylindrical housing 2 made of sheet steel. With an upper annular end 3, the housing 2 accommodates a cam follower roller 4. This projects slightly beyond the annular end 3 and runs on a bolt 6 via a bearing 5 designed as a plain bearing with an intermediate ring 36. The intermediate ring 36 is held at the ends in half-shell-like receptacles 7 by diametrically opposed, inwardly displaced flats 8 of the housing 2. The flats 8 lie axially below a closed circumferential ring 33 of the housing 2 and have lower beams 12 facing away from the upper annular end 3. The latter project through the housing 2 like a bowstring.

[0019] A separate bridge piece 10 (see Fig. 3) extends axially below the flat 8 in the housing 2. This bridge piece has an upper and a lower end face 11, 16. The end face 16 of the bridge piece 10, facing a lower annular end face 15 of the housing 2, has a central contact surface for a pump piston.

[0020] The bridge piece 10 is not ring-shaped on the outer edge (see also Fig. 3). 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° to the aforementioned ring segments 18, two further, similar ring segments (not labeled) rest against the inner shell 14 of the housing 2. As can be seen, four recesses 35 are formed between the ring segments 18.

[0021] As can be seen from Figure 1, a cover plate 19 lies loosely axially on the upper end 11 of the bridge piece 10 (see also Figure 2). The lower beams 12 of the flat 8 are located directly on the upper side 20 of the cover plate, facing away from the bridge piece 10. This structure is fixed in the direction of the lower annular end 15 of the housing 2 by means of a retaining ring 17 on the inner casing 14 of the housing 2. Four perforations 34 designed as bores extend through the cover plate 19, each of which communicates with a continuous recess 35 below it in the bridge piece 10. This design allows the passage of lubricating oil or air during the oscillating operation of the tappet 1.

[0022] A path for the targeted supply of lubricating oil to the bearing 5 is provided in the tappet 1. The housing 10 has two diametrically opposed passages 21 for the hydraulic oil. These are in fluid communication upstream with a reservoir 22 each formed as a flat on the outer casing 9 of the housing 2 (see Fig. 1). The lubricating oil is supplied to the two reservoirs 22 via a respective supply line in an axial guide (not shown) for the tappet 1. If necessary, only one supply line can be provided, and one of the reservoirs 22 is connected to the other reservoir 22, for example, via a circumferential groove.

[0023] Starting from each of the two ring segments 18, the lubricating oil is conveyed through a bag-like radial channel 23 formed between the bridge piece 10 and the cover plate 19, with the bridge piece 10 being formed in a groove-like manner at its upper end 11. This formation (the radial channel 23) can also, as shown in Figure 3, extend from one ring segment 18 to the other.

[0024] Downstream, the respective radial channel 23 communicates with a bore-shaped passage 24 in the cover plate 19, which has an outlet 25 at a gap 26 between the cam follower roller 4 and an inner wall 27 of the respective flat. A riser channel 28 is applied in the inner wall 27 for the final transfer of the lubricating oil towards the bearing 5. The passage 24 with the outlet 25 can also be designed such that an oblique and / or fanned-out application of lubricating oil occurs at the gap 26. From the outer edge 13 of the bridge piece 10, a one-piece anti-rotation nose 29 protrudes from the further ring segment, 90° circumferentially offset from its two ring segments 18. As shown in Fig. 1, this runs through an axial slot 30 extending from the lower annular end 15 of the housing 2 and projects beyond the outer casing 9 of the housing 2.This creates a simple anti-twist device for the plunger 1 in its guide and eliminates the need for a separate anti-twist element.

[0025] Likewise, an anti-rotation nose 32 protrudes in one piece from an outer edge 31 of the cover plate 19 (see Fig. 2), which, together with the aforementioned anti-rotation nose 29 of the bridge piece 10, is inserted into the axial slot 30 of the housing 2 without projecting beyond the outer casing 9 of the housing 2.

[0026] List of reference numbers ) Tappet ) Housing ) Annular end ) Cam roller ) Bearing ) Bolt ) Mountings ) Flat ) Outer casing 0)Bridge piece 1 )End 2)Lower beam 3)Outer edge 4)Inner casing 5)Annular end 6)End 7)Retaining ring 8)Ring segment 9)Cover plate 0)Top 1 )Passage 2)Reservoir 3)Radial channel 4)Passage 5)Outlet 6)Gap )Inner wall )Rising channel )Anti-rotation nose)Axial slot )Outer edge )Anti-rotation nose)Rotating ring )Perforation )Recess )Intermediate ring

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 flanges (8) of the housing (2), which flanges (8) run vertically in sections on the outer casing (9) of the housing (2), wherein the housing (2) is penetrated axially below the flanges (8) by a separate bridge piece (10), which, with its upper end (11), is at least indirectly in contact with the lower beam (12) of the flanges (8) and, at least partially, bears with its outer edge (13) against an inner casing (14) of the housing (2),wherein a lower end face (16) of the bridge piece (10) facing a lower annular end face (15) of the housing (2) forms an at least indirect contact surface for a tappet follower, and wherein a path for the targeted supply of the bearing (5) with lubricating oil is provided in the tappet (1), characterized in that the bridge piece (10) is snug against the inner casing (14) of the housing (2) in the circumferential region of each flat (8) via an annular segment (18) of its outer edge (13), wherein a cover plate (19) lies on the upper end face (11) of the bridge piece (10), on the upper side (20) of which, facing away from the bridge piece (10), the lower beams (12) of the flat (8) are directly located, wherein the housing (2) is cut by a passage (21) for the lubricating oil in at least one of the two annular segments (18) of the bridge piece (10),which each originates from a reservoir (22) on the outer shell (9) of the housing (2) and opens into a respective radial channel (23) formed between the bridge piece (10) and the cover plate (19), which is cut downstream of at least one passage (24) in the cover plate (19), which has an outlet (25) in the longitudinal section between the flats (8) of the housing (2), and wherein the reservoir (22), the passage (21), the radial channel (23) and the passage (24) are components of the one- or two-sided path for the lubricating oil.

2. Tappet according to claim 1, characterized in that, seen in the axial direction of the cam roller (4), the outlet (25) of the passage (24) of the cover plate (19) is located at a gap (26) between the cam roller (4) and an inner wall (27) of the respective flat (8), wherein in the inner wall (27) a riser channel (28) runs as a further component of the path for the lubricating oil for its further transmission in the direction of the bearing (5).

3. Tappet according to claim 1, characterized in that the reservoir (22) is present as a flat or annular groove on the outer shell (9) of the housing (2).

4. Tappet according to claim 1, characterized in that the bridge piece (10) is a flat or curved plate, wherein from the outer edge (13) of the bridge piece (10), circumferentially offset from its two ring segments (18), an anti-rotation nose (29) projects in one piece, which runs either through an axial slot (30) extending from the lower annular end (15) of the housing (2) or through a window of the housing (2) and projects beyond the outer casing (9) of the housing (2), wherein from an outer edge (31) of the cover plate (19) an anti-rotation nose (32) projects in one piece, which at the same time as the anti-rotation nose (29) of the bridge piece (10) projects either into the axial slot (30) or the window and ends there.

5. Tappet according to claim 1, characterized in that a sliding bearing is provided as the bearing (5) for the cam roller (4) on the bolt (6).

6. Tappet according to claim 1, characterized in that the outer shell (9) of the housing (2), immediately at its upper annular end (3), is a closed circumferential ring (33), axially below which the two flats (8) follow.

7. Tappet according to claim 1, characterized in that the radial channel (23) between the bridge piece (10) and the cover plate (19) in the upper end (11 ) of the bridge piece (10) and passes from one of its ring segments to the other (18).

8. Tappet according to claim 1, characterized in that the cover plate (19) is either glued, welded or snapped to the bridge piece (10) and / or that sealing compound is applied between them.

9. Tappet according to claim 1, characterized in that at least one perforation (34) passes through the cover plate (19), which perforation communicates with a continuous recess (35) in the bridge piece (10) located underneath it.

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