HIGH STIFFNESS LOW MASS ROCKER ARM

Abstract

A rocker arm is provided that includes a body which is comprised of a single vertical wall having an I-shape cross section and an axle that extends perpendicular from the vertical wall area for making contact with a valve and a pivot point. The pivot point for the rocker arm may be located centrally or at the end of the rocker arm that is opposite the rocker arm valve arm. An external cam follower bearing is mounted on the axle on each side of a single vertical wall. The rocker arm of the invention is characterized by a relatively reduced mass and has a stiffness that exceeds limits achieved by known prior art designs for an overhead cam and cam follower valve train; the gain in stiffness being attributed to the body's I-shape cross-section relative to conventional prior art rocker arms having a U-shape or dual vertical wall cross-section.

Description

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates schematically a cam and cam-follower rocker arm valve train design that includes an overhead cam, hydraulic lash adjuster, valve, valve spring and rocker arm with a rotatable bearing positioned on the rocker arm at a point between the valve contact end and the opposite last adjuster end of the rocker arm.

FIG. 1A illustrates the cam riding on the external cam-follower bearing in a cross section along A-A of FIG. 1.

FIG. 2 illustrates the I-shape cross-sectional configuration of the rocker arm body of the invention with FIGS. 2A, 2B and 2C being cross-sectional views along lines A-A, B-B and C-C respectively of FIG. 2.

FIGS. 3, 3A, 3B and 3C illustrate U-shape cross-sectional views corresponding to those of FIG. 2 to illustrate the U-shape cross-sectional configuration of prior art rocker arm bodies.

FIG. 4 is a perspective view of the U-shape cross-section prior art rocker arm body.

FIG. 5 is an exploded perspective view of the components of the rocker arm of the invention that includes the main body, the cam-follower bearings, the bearing plates and a retaining pin.

FIG. 6 is an alternative exploded perspective view of the components of the rocker arm of the invention that includes the bearing plate and an arrangement of needles around the axle of the body.

FIG. 7 is a perspective view of the rocker arm of the invention comprising the assembled components of FIG. 5.

FIG. 8 is a perspective view of the rocker arm of the invention depicting FIG. 7 in a valve train.

FIG. 9 shows the prior art U-shape cross-section rocker arm of FIG. 4 in a valve train.

FIG. 10 is an alternative embodiment illustrating the rotatable cam positioned at one end of the rocker arm as distinguished from the central position shown in FIG. 8.

FIG. 11 illustrates the alternative rocker arm containing a rotatable cam on one end of the rocker arm.

FIG. 12 is an alternative perspective view similar to that of FIG. 1 in which the rocker arm of the invention is arranged so as to pivot about a fixed shaft instead of engaging a hydraulic lash adjuster.

FIG. 13 is a perspective view of the rocker arm shown in the assembly of FIG. 12.

Claims

1. A rocker arm characterized by relatively high stiffness and low mass comprising: a. an elongated lever body having an I-shape cross-section, and having a first valve end, a mounting pivot point and a cam follower bearing point;b. the cam follower point comprising an axle positioned transversely through said lever at said point, said axle having an extension on either side of the lever; i. a rotatable cam-follower bearing mounted on said axle and extending from each of the sides of the lever;ii. bearing plates mounted on said axle outboard of each of said cam-follower bearings to retain the cam-follower bearings on the axle; andiii. a retaining pin for securing said cam-follower bearings and bearing plates to provide an integrated rocker arm assembly.

2. The rocker arm of claim 1 wherein the cam follower bearing is centrally located on the rocker arm.

3. The rocker arm of claim 1 wherein the cam follower is located at one end of the rocker arm.

4. The rocker arm of claim 1 in which the transverse axle is provided with circumventing needles over which said cam-follower bearing are mounted to reduce bearing friction.

5. The rocker arm of claim 2 in which one end of the vertical I-shape body is provided with a pivot end and the opposite end of said body is provided with a valve pad.

6. The rocker arm of claim 3 in which one end of the vertical I-shape body is provided with a pivot end and the opposite end of said body is provided with a valve pad.

7. The rocker arm of claim 5 wherein the pivot end comprises a generally concave configuration.