阅读说明：本技术 用于高压燃料泵的挺杆 (Tappet for high pressure fuel pump ) 是由 诺伯特·盖尔 马可·容克 于 2021-06-17 设计创作，主要内容包括：提出一种高压燃料泵的挺杆(1),挺杆(1)具有壳体(2),在壳体的驱动侧的端部(3)中布置有两个在直径上对置的孔(4),在孔的里面具有销栓(5),凸轮滚子(7)经由中间环(6)在销栓上运动,其中,沿轴向在凸轮滚子(7)下方,桥形件(8)位于挺杆(1)内,桥形件的朝向壳体(2)的从动侧的端部(9)的下侧(10)具有用于随动件的贴靠部(11),其中,在外表面(12)上未涂覆的所述销栓(5)以及在其孔(13)上未涂覆的所述中间环(6)通过压配合彼此接合,并且其中,销栓(5)能够相对于壳体(2)的孔(4)自由旋转运动,以及滚子组件的轴向固定仅通过中间环(6)以其外端面(14)在壳体(2)的内壁(15)上的止推来进行。(A tappet (1) for a high-pressure fuel pump is proposed, the tappet (1) having a housing (2), two diametrically opposed bores (4) being arranged in a drive-side end (3) of the housing, a pin (5) being provided in the bores, on which a cam roller (7) is moved via an intermediate ring (6), wherein a bridge (8) is located in the tappet (1) axially below the cam roller (7), the underside (10) of the end (9) of the bridge facing the output side of the housing (2) having an abutment (11) for a follower, wherein the pin (5) which is not coated on an outer surface (12) and the intermediate ring (6) which is not coated on its bore (13) are joined to one another by a press fit, and wherein the pin (5) can be freely rotationally moved relative to the bore (4) of the housing (2), and the roller assembly is axially fixed only by the intermediate ring (6) with its outer end face (14) on the housing (2) Thrust on the inner wall (15).)

1. A tappet (1) having a sliding-mounted cam roller (7), the tappet (1) being provided for a high-pressure fuel pump of an internal combustion engine and having a housing (2), two diametrically opposed bores (4) being arranged in a drive-side end (3) of the housing, a pin (5) being provided inside the bores, on which pin the cam roller (7) is moved via an intermediate ring (6), wherein axially below the cam roller (7) a bridge (8) is located in the tappet (1), the underside (10) of the end (9) of which bridge facing the driven side of the housing (2) has an abutment (11) for a follower, characterized in that the pin (5) which is uncoated on an outer surface (12) and the intermediate ring (6) which is uncoated on its bore (13) are joined to one another by a press fit, wherein the pin (5) is freely rotationally movable relative to the bore (4) of the housing (2) and the axial fixing of the roller assembly comprising the pin (5), the intermediate ring (6) and the cam roller (7) is effected exclusively by thrust of the intermediate ring (6) with its outer end face (14) against the inner wall (15) of the housing (2).

2. A tappet according to claim 1, characterised in that the outer surface (23) of the intermediate ring (6) and/or the inner surface (16) of the cam roller (7) has a coated layer (17, 18) of hard material.

3. A tappet according to claim 1, characterised in that the pin (5) is completely hardened and that only the annular section (19) of the pin, which is located at the outer surface (12) in the bore (4) of the housing (2), is provided with a layer (20) of a hard material applied.

4. A tappet according to claim 1, characterised in that a hard material layer (22) is applied on the outer end face (14) of the intermediate ring (6).

Technical Field

The invention relates to a tappet having a sliding-mounted cam roller, which is provided for a high-pressure fuel pump of an internal combustion engine and has a housing, two diametrically opposed bores being arranged in a drive-side end of the housing, a pin being provided in the bores, on which the cam roller is moved via an intermediate ring, wherein a bridge is located in the tappet axially below the cam roller, and the underside of the end of the bridge facing the output side of the housing has an abutment for a follower.

Background

A tappet of the type described with a sliding-mounted roller assembly having an intermediate ring between the pin and the cam roller is known from DE 102018120265 a1, fig. 2 and paragraph [0013 ]. The components are rotationally movable relative to one another, wherein hydrodynamic plain bearings are present during operation in a) the annular gap between the bolt and the intermediate ring and b) the annular gap between the intermediate ring and the cam roller, respectively. The mating surfaces involved at the two annular gaps are provided with a layer of hard material (DLC layer) that reduces friction and wear, which after coating is also subjected to a brushing process. Axial fixing of the pin bolt is achieved by enlarging its end by means of radial spot riveting or caulking, wherein snap ring fixing devices are also known.

DE 102009013130 a1 discloses a tappet of the type described above, but with a needle-bearing cam roller.

Disclosure of Invention

The object is to design a tappet that is suitable for very high loads and high rotational speeds in pump transmissions and at the same time can be produced inexpensively.

According to the invention, the object is achieved in that the pin, which is uncoated on the outer surface, and the intermediate ring, which is uncoated on its bore, are joined to one another by a press fit, wherein the pin can move freely in rotation relative to the bore of the housing, and the axial fixing of the roller assembly is effected exclusively by the thrust (anal uf) of the intermediate ring with its outer end face against the inner wall of the housing.

The hydrodynamic plain bearing thus only moves in the radially outer annular gap between the intermediate ring and the cam roller, whereas in the radially inner annular gap a permanent press-fit composite is now achieved between the pin and the intermediate ring and therefore no relative rotation can occur anymore.

Purely functionally, the above has the advantage that a higher circumferential speed is present by the plain bearing being formed only on a larger diameter, and thus the elastohydrodynamic lubrication is significantly improved. The fraction of solid friction and mixed friction decreases. This bearing is excellent in terms of the continuously increasing pump pressure and rotational speed of the drive (camshaft, crankshaft, balance shaft or auxiliary shaft).

At the same time, in a press-fit composite structure which only exists as a "standard rolling bearing composite structure" in terms of surface quality, it is possible to install a pin with a smaller diameter, so that, for example, the two pin bores of the housing can be relatively close to the upper annular end of the housing. At the same time, it is now possible to use annular cam rollers of thinner construction, so that they are relatively "easy to rotate" due to their low mass and, in operation, for example in start-up/run-up, slip is less pronounced due to the known wear marks. The stepped pin known from the background art with a thin cam ring can be dispensed with, which can only be fitted without problems into the U-shaped pocket of the housing.

Furthermore, the production costs are reduced by the elimination of the hitherto essential hard material coating between the outer surface of the pin and the bore of the intermediate ring and the subsequent painting of the surface. Although the assembly process is automatable on the coating chamber, however, it is mainly a complicated manual feed (threading) and removal.

The pin to be pressed against the intermediate ring is guided laterally in this case into one of the bores of the housing, wherein the intermediate ring together with the rollers fitted thereon is held in the interior of the housing. The pin is then pressed against the intermediate ring by means of a punch or the like.

The invention also has the advantage that the previously existing, mainly force-consuming fastening by caulking, radial riveting or the like on a fully hardened bolt can be dispensed with, which fastening is accompanied by the risk of, for example, influencing the housing or even its ground raceway (outer surface) or loosening the connection. The axial fixing of the roller assembly and the pin bolt is therefore only achieved by thrust of the intermediate ring via its outer end face on the inner face of the housing. The outer end face of the cam roller is slightly drawn in with respect to the outer end face of the intermediate ring.

In order to increase the load resistance and wear resistance of the roller assembly, it is proposed in a particularly preferred development of the invention that at least one of the annular play-outs of the "remaining" plain bearing is provided with a hard material layer, such as a DLC layer.

In the same way or independently thereof, the annular section of the bolt extending in the bore region of the housing can also be coated with a hard material, so that friction and wear in the region of the rotationally movable bolt are minimized. If necessary, the bolt can also be moved on the bush in the bore.

Likewise, the outer end face of the intermediate ring which is in contact with the inner face of the housing can be formed with a layer of coated hard material, or the inner face can also be formed with a layer of coated hard material, alone or together with the last-mentioned design measure.

Drawings

With respect to the drawings:

figure 1 shows a tappet in an overall perspective view;

FIG. 2 shows a longitudinal section of the tappet along the roller axis, an

Fig. 3 shows a cross-sectional view of the tappet rotated 90 ° with respect to fig. 2.

Detailed Description

Fig. 1 shows a tappet 1, also referred to as a roller tappet or a pump tappet, from a basic known structure of a tappet. The tappet 1 has a hollow-cylindrical housing 2, in the drive-side end 3 of which two diametrically opposed bores 4 are in a recessed flattened area 24. In the bore 4 is placed a pin 5 which is rotatable and slightly axially movable relative to the bore and which carries a cam roller 7 via an intermediate ring 6. Below the cam roller 7 in the axial direction, a thin-walled bridge 8 (see fig. 2, 3) is mounted, the underside 10 of the end 9 of which facing the output side of the housing 2 has an abutment 11 for a follower (pump piston).

The bolt 5, which is preferably completely hardened, is permanently pressed by its outer surface 12 against the bore 13 of the intermediate ring 6. In this respect, no sliding bearings are present on this radially inner annular region. The surface quality of the above-mentioned contact area is reduced to the extent of "standard rolling bearings".

Only the thin-walled cam roller 7 is held in rotatable movement relative to the now fixed intermediate ring 6, wherein it must not be explained that the hydrodynamic plain bearing is formed only between the outer surface 23 of the intermediate ring 6 and the inner surface 16 of the cam roller 7. The outer surface 23 and the inner surface 16 are provided with a DLC layer.

The roller assembly is axially fixed by thrust of the intermediate ring 6 with its outer end face 14 against the inner wall 15 of the housing 2.

List of reference numerals

1 tappet

2 casing

3 end of

4 holes

5-pin bolt

6 intermediate ring

7 cam roller

8 bridge

9 end part

10 lower side

11 contact part

12 outer surface

13 holes

14 outer end face

15 inner wall

16 inner surface

17 hard material layer

18 hard material layer

19 annular segment

20 hard material layer

22 hard material layer

23 outer surface of

24 flattened section