ROCKER ARM

Abstract

Rocker arm for actuating at least one gas exchange valve of an internal combustion engine having an elongated lever body (2) with a floor (3) and with side walls (4,5) angled away therefrom, wherein a first end section (6) of the lever body (2) has a cup (9) for a support element formed in the floor (3), and in that a section (7) near the center is provided with a cam engagement surface and in that a second end section (8) of the lever body (2) has a contact surface (12) for a valve stem end of the gas exchange valve, wherein a crossbar (13) extends between the section (7) near the center and the second end section (8), wherein the crossbar (13) has a stamping 14) that is provided on the side facing away from the section (7) near the center.

Description

FIELD OF THE INVENTION

The invention concerns a rocker arm for actuating a gas exchange valve of an internal combustion engine.

BACKGROUND OF THE INVENTION

In internal combustion engines, rocker arms are located in a valve train as transmission elements between cams and the gas exchange valves to be actuated. Rocker arms consist of a lever body that is supported at one of its ends on a support element and with its other end engages, through a contact surface, the gas exchange valve to be opened. In a section of the lever body near the center, a cam pickup surface is provided on which a cam of a camshaft runs during operation of an internal combustion engine, causing a pivoting motion of the rocker arm. The cam pickup surface can be implemented as a sliding surface or as a cam roller.

A rocker arm for actuating a gas exchange valve of an internal combustion engine is known from DE 10 2008 029,333 A1. At one end, the rocker arm has an oval opening that encompasses a valve stem end of the gas exchange valve. In addition, the rocker arm provides a cam roller in a section near the center.

WO2011/157499 A1 discloses a rocker arm that has a cam roller supported on an axle pin by means of a needle roller and cage assembly. A contact surface for a valve stem end of the gas exchange valve is provided at one end of the rocker arm. Side bars are provided in the region of the contact surface to guide the rocker arm on the valve stem end.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a rocker arm that can be manufactured economically and that ensures adequate stiffness.

According to the invention this object is attained by a rocker arm for actuating at least one gas exchange valve of an internal combustion engine having an elongated lever body with a floor and with side walls angled away therefrom, wherein a first end section of the lever body has a cup for a support element formed in the floor, and in that a section near the center is provided with a cam engagement surface and in that a second end section of the lever body has a contact surface for a valve stem end of the gas exchange valve, wherein a crossbar extends between the section near the center and the second end section and wherein the crossbar has a stamping that is provided on the side facing away from the section near the center.

In the rocker arm according to the invention, the crossbar is provided with a stamping. The stamping can be an embossing, for example. The stamping in the crossbar makes it possible to avoid contact between the valve stem end and the lever body during pivoting motions of the rocker arm. The necessary stiffening of the rocker arm is ensured by the crossbar, which in turn results in increased strength of the rocker arm.

In a preferred embodiment of the invention, the shape of the stamping is matched to the valve stem end. This means that the shape of the stamping is designed to be complementary to the shape of the valve stem end. Preferably the stamping is implemented as a cylindrical molding.

Preferably the second end section of the lever body has a W-shaped profile when viewed in cross-section. As a result of the W-shaped profile, the side bars known from the prior art that would be necessary for valve guidance are eliminated. This has the advantage that the weight of material used can be reduced, and thus the production costs can be decreased. The W-shaped profile preferably is open in the direction facing away from the gas exchange valve. However, a reversed arrangement of the W-shaped profile is also possible.

In another embodiment of the invention, a distance between a longitudinal center of the cup and a center of rotation of the cam pickup surface is half as large as or less than half a distance between the longitudinal center of the cup and a center of a contact region of the gas exchange valve at the contact surface. Accordingly, the cam pickup surface can be positioned close to the contact region of the gas exchange valve. This has the advantage that the overall length of the rocker arm can be shortened to achieve a compact component.

In one embodiment, the cam pickup surface is implemented by a cam roller, and the section near the center has a recess in the floor that serves to accommodate the cam roller. The recess in the floor creates the necessary free space for the cam roller so that rotary motion of the cam roller is possible.

Preferably, the lever body is either produced by stamping and forming techniques from a sheet metal material, or by extrusion molding. However, other materials and manufacturing methods are also possible.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is explained below using three figures.

They show:

FIG. 1 a rocker arm according to the invention in a perspective view,

FIG. 2 a bottom view of the rocker arm according to the invention, and

FIG. 3 a longitudinal cross-section through the rocker arm according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 each show different views of a rocker arm 1 according to the invention. The rocker arm 1 has an elongated lever body 2, which has a floor 3 and side walls 4, 5 angled away therefrom. The floor 3 and the side walls 4, 5 form a W-shaped profile when viewed in cross-section. Moreover, the lever body 2, which is made of a sheet metal material, is divided into a first end section 6, a section 7 near the center, and a second end section 8.

Formed in the part of the floor 3 running along the first end section 6 is a cup 9, which rises between the side walls 4, 5. The cup 9 provides support on a support element that is not shown.

In the region of the section 7 near the center, each of the side walls 4,5 has a bore 10 serving to support a cam roller that is not shown. The cam roller that is not shown defines a cam pickup surface. A recess 11 designed with a rectangular outer contour is provided in the part of the floor 3 running along the section 7 near the center.

A contact surface 12 for a valve stem end, not shown, of a gas exchange valve is provided on the part of the floor 3 running along the second end section 8 of the lever body 2. A crossbar 13 that is provided between the side walls 4,5 extends between the second end section 8 and the section 7 near the center. The crossbar 13 has a stamping 14, which is implemented as a cylindrical molding, on the side facing away from the section 7 near the center. The stamping 14 makes it possible for adequate clearance of the contact surface relative to the gas exchange valve, not shown, to be present during pivoting motions of the rocker arm 1.

FIG. 3 shows a longitudinal cross-section through the rocker arm 1 according to the invention. This illustrates the relationship of the individual sections to one another. In the first end section 6, the cup 9 has a longitudinal center 15. Each of the bores 10 has a center point 16 that defines a center of rotation 17 for the cam pickup surface. The contact surface 12 defines a contact region 18 of the gas exchange valve, not shown.

A distance L1 is defined between the longitudinal center 15 of the cup 9 and the center of rotation 17 of the cam pickup surface. A distance L2 is defined between the longitudinal center 15 of the cup 9 and a center of the contact region 18 of the gas exchange valve. The distance L1 here is half as large as or less than half the distance L2. This distance ratio makes possible a short, compact lever body 2.

LIST OF REFERENCE CHARACTERS

• 1 rocker arm
• 2 lever body
• 3 floor
• 4 side wall
• 5 side wall
• 6 first end section
• 7 section near the center
• 8 second end section
• 9 cup
• 10 bore
• 11 recess
• 12 contact surface
• 13 crossbar
• 14 stamping
• 15 longitudinal center of the cup
• 16 center point
• 17 center of rotation
• 18 contact region of the gas exchange valve
• L1 distance
• L2 distance

Claims

1. Rocker arm for actuating at least one gas exchange valve of an internal combustion engine having an elongated lever body (2) with a floor (3) and with side walls (4,5) angled away therefrom, wherein a first end section (6) of the lever body (2) has a cup (9) for a support element formed in the floor (3), and in that a section (7) near the center is provided with a cam engagement surface and in that a second end section (8) of the lever body (2) has a contact surface (12) for a valve stem end of the gas exchange valve, wherein a crossbar (13) extends between the section (7) near the center and the second end section (8), characterized in that the crossbar (13) has a stamping (14) that is provided on the side facing away from the section near the center (7).

2. Rocker arm according to claim 1, wherein a shape of the stamping (14) is matched to the valve stem end.

3. Rocker arm according to one of the preceding claims, wherein the second end section (8) of the lever body (2) has a W-shaped profile when viewed in cross-section.

4. Rocker arm according to one of the preceding claims, wherein a distance (L1) between a longitudinal center (15) of the cup (9) and a center of rotation (17) of the cam pickup surface is half as large as or less than half a distance (L2) between the longitudinal center (15) of the cup (9) and a center of a contact region (18) of the gas exchange valve at the contact surface (12).

5. Rocker arm according to one of the preceding claims, wherein the cam pickup surface is implemented by a cam roller, and wherein the section near the center has a recess (11) in the floor that serves to accommodate the cam roller.

6. Rocker arm according to one of the preceding claims, wherein the lever body (2) is either produced by stamping and forming techniques from a sheet metal material, or by extrusion molding.