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: a first opening, a second opening, a first protrusion extending transversely within the roller pocket from one of the two side walls, and a second protrusion extending transversely within the roller pocket from a remaining one of the two side walls, and the first and second protrusions separating the first and second openings such that a first end of each of the first and second protrusions is adjoined to the first opening and a second end of each of the first and second protrusions is adjoined to the second opening, the first and second protrusions forming a third opening defined by a first transverse distance, the first transverse distance less than: i) a second transverse distance of the first opening, and ii) a third transverse distance of the second opening, and each of the first and second protrusions having a guide face configured to limit axial movement of the cam roller within the roller pocket.

2. The rocker arm of claim 1, wherein the roller pocket is formed within a middle region of the arm body.

3. The rocker arm of claim 1, wherein the third opening is adjoined to the first and second openings.

4. The rocker arm of claim 1, wherein the third opening is arranged between the first opening and the second opening relative to a longitudinal direction of the roller pocket.

5. 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 two 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: a middle region having the roller pocket, two side walls, and two webs, the two webs and the two side walls delimiting the roller pocket, and detaching the at least one connecting web to form at least one protrusion, the at least one protrusion extending transversely relative to the roller pocket and configured to engage an end face of the cam roller.

6. The method of claim 5, wherein the at least one connecting web is detached in a punching process.

7. The method of claim 5, wherein a spherical cap is produced via a forming process, the spherical cap configured as a pivot point in one of the two webs, and the one of the two webs directly adjoins the roller pocket.

8. The method of claim 5, wherein the at least one protrusion includes two protrusions configured to extend towards each other.

9. The method of claim 5, wherein the at least one protrusion extends from an upper edge of at least one of the two side walls.

10. The method of claim 5, wherein each of the two side walls includes a bore, each bore configured to receive a roller axle configured for mounting the cam roller.

11. The method of claim 5, wherein the two side walls are connected to each other via the at least one connecting web.

12. 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: a first opening, a second opening, and two transversely extending protrusions forming a third opening, the two transversely extending protrusions separating the first opening from the second opening, each of the two transversely extending protrusions having a first end adjoined to the first opening, and a second end adjoined to the second opening, and each of the two transversely extending protrusions forming a guide face configured to engage a respective end face of the cam roller, and the two transversely extending protrusions are spaced apart a first transverse distance within the roller pocket, and the first transverse distance is less than: i) a second transverse distance of the first opening, and ii) a third transverse distance of the second opening.

13. The rocker arm of claim 12, wherein the roller pocket is formed within a middle region of the arm body.

14. The rocker arm of claim 12, wherein the pivot is configured with a splash bore to provide lubricant to the cam roller.

15. The rocker arm of claim 12, wherein the third opening is arranged between the first opening and the second opening relative to a longitudinal direction of the roller pocket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For further explanation of the disclosure, reference is made to the drawings which show an exemplary embodiment in simplified form. In the drawings:

(2) 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,

(3) 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,

(4) FIG. 3 shows an enlarged partial view of the arm body in the region of the connecting web,

(5) 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,

(6) 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,

(7) FIG. 6 shows a top view of the arm body from FIG. 4,

(8) FIG. 7 shows an enlarged partial view of the top view of the arm body shown in FIG. 6,

(9) 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

(10) FIG. 9 shows a top view of the rocker arm.

DETAILED DESCRIPTION

(11) 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.

(12) 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 32 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.

(13) 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.

(14) 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 to form an opening 29 that is adjoined to openings 5, 6. These protrusions 17, 18 have guide faces 19 and 20 which run towards each other spaced by a transverse 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 protrusions 17, 18 separate the two openings 5, 6, such that a first end 30 of each of the protrusions is adjoined to the openings 5, and a second end 31 of each of the protrusions is adjoined to the opening 6 (see FIG. 7). The transverse distance S between the guide faces 19, 20 is lens than, i) a transverse distance S1 of the opening S that is adjoined to the protrusions 17, 18, and ii) a transverse distance S2 of the opening 6 that is adjoined to the protrusions 17, 18. 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.

(15) 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.

(16) 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

(17) 1 Plate 2 Outer edge of 1 3 Outer edge of 1 4 Connecting web 5 Opening 6 Opening 7 Valve stem support 8 Spherical cap, pivot point 8a Cap wall 9 Arm body 10 Side wall 11 Side wall 12 Roller pocket 13 Web 14 Web 15 Splash bore 16 Collar 17 Protrusion 18 Protrusion 19 Guide face 20 Guide face 21 Cam roller 22 End face of 21 23 End face of 21 24 Roller axle 25 Needle roller bearing 26 Bore 27 Rocker arm 28 Doubling 29 Opening 30 First end of 17 and 18 31 Second end of 17 and 18 32 Middle region S Transverse distance between 19 and 20 S1 Transverse distance of 5 S2 Transverse distance of 6