ROCKER ARM FOR A VALVE TRAIN OF AN INTERNAL COMBUSTION ENGINE, AND METHOD FOR THE NON-CUTTING PRODUCTION OF AN ARM FROM STEEL SHEET

Abstract

A rocker arm has two side walls and two webs which run transversely with respect to the side wall. The webs connect the side walls to one another on end-side sections, wherein a valve stem support is configured on one of the webs, and a spherical cap is configured on the other web. A cam roller is arranged in a roller pocket which is delimited by the webs and the side walls. The cam roller is mounted rotatably on a roller axle which is fixed in the side walls. Projections are arranged within the roller pocket such that they are spaced apart from the respective web to guide the cam roller. The projections extend from the side walls in the direction of the cam roller to form guide surfaces which interact with end surfaces of the cam roller.

Claims

1. A rocker arm for a valve train of an internal combustion engine, the rocker arm comprising: an arm body produced by forming a steel sheet, the arm body having a U-shaped cross-section configured to open toward an engine valve stem, the arm body having: two side walls connected together at end portions via webs extending transversely to the two side walls, a valve stem support formed on one of the webs, a pivot formed on another of the webs, and a roller pocket delimited by the webs and the two side walls, the roller pocket configured to receive a cam roller rotatably mounted on a roller axle fixed to the two side walls, the roller pocket having at least one protrusion extending within the roller pocket from at least one of the side walls toward the cam roller, the at least one protrusion forming a guide face configured to limit axial movement of the cam roller with the roller pocket.

2. The rocker arm as claimed in claim 1, wherein the roller pocket extends to the another of the webs, the another of the webs formed with a spherical cap configured as the pivot.

3. The rocker arm as claimed in claim 2, wherein the another of the webs is offset downward relative to an upper edge of the side walls.

4. A method for forming a rocker arm body from steel sheet for a valve train of a reciprocating piston internal combustion engine, the method comprising: punching a plate from a steel sheet, punching at least two openings from the plate, the at least one openings: i) defining a bone-shaped outer contour with a longitudinal extent and a transverse extent, ii) forming a roller pocket configured to receive a cam roller, and iii) defining at least one connecting web configured to separate the at least two openings, the at least one connecting web extending in the transverse extent of the bone-shaped outer contour, forming the plate to a U-shape, the U-shape defining two side walls and two webs, the two webs extending transversely to the side walls, detaching the at least one connecting web to form at least one protrusion, the at least one protrusion configured to engage the cam roller.

5. The method as claimed in claim 4, wherein the at least one connecting is detached in a punching process.

6. The method as claimed in claim 4, wherein a spherical cap is produced via a forming process, the spherical cap configured as a pivot point in one of the two webs, wherein the one of the two webs directly adjoins the roller pocket.

7. The rocker arm of claim 1, wherein the at least one protrusion includes two protrusions configured to point towards each other.

8. The rocker arm of claim 1, wherein the at least one protrusion extends from an upper edge of at least one of the two side walls.

9. The rocker arm of claim 1, wherein the at least one protrusion is formed integrally with the roller pocket.

10. The rocker arm of claim 2, wherein the another of the webs extends from a lower edge of the spherical cap and is connected to one of the two side walls via a doubling.

11. A rocker arm for a valve train of an internal combustion engine, the rocker arm comprising: an arm body produced by forming a steel sheet and having a U-shaped cross-section configured to open toward a valve stem, the arm body having: two side walls connected together at end portions of the arm body via webs running transversely to the side walls, a valve stem support formed on one of the webs, a pivot formed on another of the webs, and a roller pocket delimited by the webs and the two side walls, the roller pocket configured to receive a cam roller rotatably mounted on a roller axle fixed on the two side walls, the roller pocket having at least one protrusion extending from a longitudinal side of the roller pocket, the at least one protrusion forming a guide face configured to engage the cam roller.

12. The rocker arm of claim 11, wherein the at least one protrusion engages an end face of the cam roller.

13. The rocker arm of claim 11, wherein the at least one protrusion extends transversely from the longitudinal side of the roller pocket.

14. The rocker arm of claim 11, wherein the at least one protrusion comprises a first protrusion extending from a first longitudinal side of the roller pocket and a second protrusion extending from a second longitudinal side of the roller pocket.

15. The rocker arm of claim 14, wherein the first protrusion includes a first guide face and the second protrusion includes a second guide face, and the first guide face is spaced apart from the second guide face by a distance S, the distance S less than a transverse width of the roller pocket.

16. The rocker arm of claim 11, wherein the pivot is configured with a splash bore to provide lubricant to the cam roller.

17. The rocker arm of claim 11, wherein the at least one protrusion is formed integrally with the longitudinal side of the roller pocket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For further explanation of the disclosure, reference is made to the drawings which show an exemplary embodiment in simplified form. In the drawings:

[0016] FIG. 1 shows a top view of a plate punched out of a steel sheet, which in a further punching process is provided with an opening having a connecting web,

[0017] FIG. 2 shows a top view of a U-shaped arm body which is produced from the plate in a non-cutting forming process, wherein the connecting web runs inside a roller pocket formed by the opening,

[0018] FIG. 3 shows an enlarged partial view of the arm body in the region of the connecting web,

[0019] FIG. 4 shows a side view of the arm body, wherein a substantial part of the connecting web has been removed and only parts thereof protrude as protrusions into the roller pocket,

[0020] FIG. 5 shows an enlarged partial view of the side view of the arm body shown in FIG. 4, showing the position and form of one of the protrusions,

[0021] FIG. 6 shows a top view of the arm body from FIG. 4,

[0022] FIG. 7 shows an enlarged partial view of the top view of the arm body shown in FIG. 6,

[0023] FIG. 8 shows a side view of a rocker arm made using the arm body of FIGS. 4 to 7 and having a cam roller, and

[0024] FIG. 9 shows a top view of the rocker arm.

DETAILED DESCRIPTION

[0025] In FIG. 1, a plate punched out of a sheet strip and having convexly curved outer edges 2 and 3 on its long sides is designated 1. This plate 1 is produced by a punching process in a first method step. In a second method step, in a further punching process, the plate 1 is provided with two openings 5 and 6 separated from each other by a connecting web 4. Without the connecting web 4 separating the openings 5 and 6, there would be as a whole one orifice of bone-shaped outer contour. During a further forming process, a U-shaped blank is produced from the plate 1.

[0026] Then by further forming processes, which may be embossing processes, a valve stem support 7 (shown in FIGS. 2, 4, 6, 8 and 9) and a spherical cap 8 (shown in FIGS. 2 to 8) are produced from this blank, giving the arm 9 shown amongst others in FIGS. 2 and 3. This arm body 9 has side walls 10 and 11 which at their upper end delimit a roller pocket 12. Outside this roller pocket 12 provided in the middle region of the arm body 9, i.e. in the region of the two ends of the arm body 9, the side walls 10 and 11 are connected together via webs 13 and 14. Here the spherical cap 8 is formed in the web 13, and as shown in FIGS. 4, 5 and 8 has a cap wall 8a and a splash bore 15. In the region of the web 14, the side walls 10 and 11 laterally delimit the valve stem support 7 formed on the underside of the web 14.

[0027] The roller pocket 12 is the substantially rectangular space delimited by the side walls 10 and 11 and the two webs 13 and 14. As shown in FIGS. 2 and 3, the connecting web 4 (still present) runs inside this roller pocket 12 between the two upper edges of the side walls 10 and 11, as provided previously in the plate 1 according to FIG. 1. If a collar 16, protruding into the roller pocket 12, is provided at least in part regions of each upper edge of the side walls 10 and 11, as shown for example in FIGS. 4, 5 and 8, the connecting web 4 shown in FIGS. 2 and 3 extends from this collar 16.

[0028] In a further method step, the connecting web 4 is removed so as to leave only the protrusions 17 and 18, shown in FIGS. 4 to 9, extending from the side walls 10 and 11 or the respective collar 16 and protruding into the roller pocket 12. These protrusions have guide faces 19 and 20 which run towards each other spaced by a distance s (see FIG. 7), which is dimensioned such that a cam roller 21 later inserted in the roller pocket 12 (as shown in FIGS. 8 and 9) is guided via these guide faces 19 and 20 by running thereon with its end faces 22 and 23. The splash bore 15 of the ball cap 8 described above is oriented so that lubricant is splashed through this onto the periphery of the cam roller 21.

[0029] For rotatable mounting of the cam roller 21 on a roller axle 24, a needle roller bearing 25 is provided which can be a full-complement needle roller bearing. As FIG. 4 in particular shows, bores 26 in which the roller axle 24 can be fixed are provided in the side walls 10 and 11. The corresponding arrangement of the cam roller 21 in the arm body 9 creates a rocker arm 27 (shown in FIGS. 7 and 8) for use in a valve train of a reciprocating piston internal combustion engine.

[0030] As furthermore shown in particular by FIG. 5, the spherical cap 8 extends from a lower end out of the web 13 and hence delimits the roller pocket 12 at this point. Thus, in this region there is no need for a wider web which would normally connect together the side walls 10 and 11 at their upper edges. Starting from the edges, the side wall 10 rather has a doubling 28 which extends downward and transforms into the web 13 so as to receive the spherical cap 8. In this way, the arm body 9 as a whole can be shortened, so that the rocker arm 27 can be designed shorter and consequently a very compact arrangement of the valve train is possible.

LIST OF REFERENCE CHARACTERS

[0031] 1 Plate [0032] 2 Outer edge of 1 [0033] 3 Outer edge of 1 [0034] 4 Connecting web [0035] 5 Opening [0036] 6 Opening [0037] 7 Valve stem support [0038] 8 Spherical cap, pivot point [0039] 8a Cap wall [0040] 9 Arm body [0041] 10 Side wall [0042] 11 Side wall [0043] 12 Roller pocket [0044] 13 Web [0045] 14 Web [0046] 15 Splash bore [0047] 16 Collar [0048] 17 Protrusion [0049] 18 Protrusion [0050] 19 Guide face [0051] 20 Guide face [0052] 21 Cam roller [0053] 22 End face of 21 [0054] 23 End face of 21 [0055] 24 Roller axle [0056] 25 Needle roller bearing [0057] 26 Bore [0058] 27 Rocker arm [0059] 28 Doubling [0060] s Distance between 19 and 20