ROCKER SUPPORT BOLT BUSHING

A bushing for taking up the gap between a support bolt and a rocker arm shaft in an internal combustion engine in order to eliminate unwanted motion and subsequent engine noise.

BACKGROUND

Technical Field

The present device is in the field of internal combustion engines, particularly the valve train components of such engines.

Summary

In a typical motorcycle engine, for example, the rocker assembly includes a rocker arm support that holds a rocker arm shaft. A rocker support bolt secures the rocker arm support and also cross-pins the rocker arm shaft in place. However, in some engines, there can be excessive clearance between the rocker support bolt and the rocker arm shaft. This can cause a loud tapping noise at higher rpms.

A round bushing placed on the rocker support bolt can take up this space and eliminate the tapping caused by the rocker arm shaft hitting the bolt. However, some bushings can be compressed and deformed during installation rather than push down into the hole. Although bushings made of more malleable materials can have the advantage of compressing during installation and then restoring to a relaxed state to expand and fill the space, they, too, can be subject to undesirable deformation on installation. Further the rocker support plate can have a casting parting ring around the circumference of the hole, which can increase the flaring problem. This can lead to problems of alignment and valve train geometry.

Substantially cylindrical bushings can address this issue, but must be precisely machined to fit both bolts and rocker plate holes, which can be expensive to produce. Non-cylindrical bushings, though, can fit a wide variety of bolt/plate combinations. What is needed is an improved bushing for a rocker support bolt to properly align and lock the rocker arm shaft, that is easy to install and can fill the clearance space while withstanding temperatures of engine operation

DETAILED DESCRIPTION

FIG. 1adepicts an exploded perspective view of a rocker arm support assembly of an engine. A rocker arm support102can have a plurality of bolts104securing a rocker arm support102and a rocker arm shaft105. As shown inFIG. 1a,some embodiments of the present device can be a bushing106having an inner surface and an outer surface, and a distal end and a proximal end. In some embodiments the inner diameter of a bushing106can be such to selectively engage longitudinally with a bolt104passing through it, but in other embodiments can be any other known and/or convenient diameter. In the embodiment shown inFIG. 1a,a bushing106can be substantially cylindrical, or have a substantially longitudinally constant outer diameter, but in other embodiments can have a longitudinally varying outer diameter. In some embodiments a bushing106can be fabricated from steel or any other known and/or convenient material, and can be hardened, spring-tempered, or subject to any other known and/or convenient process. In some embodiments, a spring-tempered material can be advantageous to maintain device performance during heat expansion.

FIG. 1bdepicts an exploded side view of the rocker arm support assembly shown inFIG. 1a.In some embodiments, a bolt104can pass through a bushing106, where they can selectively engage into a designated hole in a rocker arm support102.

FIG. 1cdepicts a detail cutaway side view of the support bolt insertion point on the rocker arm support assembly shown inFIG. 1a. As a bolt104engages with a rocker arm support102, a bolt104can also align with a notch in a rocker arm shaft105, locking it in place. In some embodiments, a bushing106can occupy the clearance space between a bolt104, a rocker arm support102, and a rocker arm shaft105, thereby tightening the fit.

In the embodiment shown inFIG. 2a, a bushing106can have sections of longitudinally varying outer diameter. In some embodiments, the distal end of a bushing106can have an outer diameter less than that of the proximal end. As shown inFIG. 2a, a bushing106can have a tapered geometry, but in other embodiments can have any other known and/or convenient geometry.

FIG. 2bdepicts an alternate embodiment of the present device as shown inFIG. 2a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 3adepicts another embodiment of the present device in which a bushing106can have sections of longitudinally varying diameter. In the embodiment ofFIG. 3a, a bushing106can have a first segment204with a larger diameter than that of at least one second segment206. In some embodiments, a first segment204can be located at the proximal end of a bushing106, with at least one second segment206at the distal end, but can have any other known and/or convenient configuration in other embodiments.

FIG. 3bdepicts an alternate embodiment of the present device as shown inFIG. 3a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106. In the embodiment shown inFIG. 3b, fabricating a bushing106from a spring-tempered material can improve device performance by allowing a bushing106to maintain pressure against a rocker arm shaft105even as a rocker assembly expands due to heat.

FIG. 4adepicts a perspective view of another embodiment of the present device, in which a bushing106can have sections of longitudinally varying outer diameter. In some embodiments, the distal end and the proximal end of a bushing106can each have an outer diameter less than that of a region substantially at the longitudinal midpoint of a bushing106. As shown inFIG. 4a, a bushing106can have a double-tapered geometry substantially symmetric about the longitudinal midpoint of a bushing106, but in other embodiments can have any other known and/or convenient geometry.

FIG. 4bdepicts an alternate embodiment of the present device as shown inFIG. 4a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 5adepicts another embodiment of the present device in which a bushing106can have sections of longitudinally varying diameter. In the embodiment ofFIG. 5a, a bushing106can have a first segment204with a larger diameter than that of at least one second segment206. In some embodiments, a first segment204can be located substantially at the longitudinal midpoint of a bushing106, with a second segments206of at the proximal and the distal end, but can have any other known and/or convenient configuration in other embodiments. In some embodiments, second segments206can be of substantially equal length, but in other embodiments can be of any other known and/or convenient lengths.

FIG. 5bdepicts an alternate embodiment of the present device as shown inFIG. 5a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 6adepicts a perspective view of another embodiment of the present device. In some embodiments, a bushing106can have a non-circular cross section with a plurality of longitudinal grooves602adjacent to longitudinal ridges604. As shown inFIG. 6a, longitudinal grooves602and longitudinal ridges604can have a rounded cross sections, but in other embodiments can have any other known and/or convenient cross-sectional geometry.

FIG. 6bdepicts an alternate embodiment of the present device as shown inFIG. 6a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

As shown inFIG. 7a, other embodiments of the present device can have at least one portion of the outer surface extruded to form at least one circumferential ridge702, which can be located substantially at the longitudinal midpoint of a bushing106. However, circumferential ridges702can be located at any other known and/or convenient point on the outer surface of a bushing106. In the embodiment ofFIG. 7a, circumferential ridges702can have a rounded cross-section, but in other embodiments can have any other known and/or convenient cross-sectional geometry.

FIG. 7bdepicts an alternate embodiment of the present device as shown inFIG. 7a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 8adepicts another embodiment of the present device. As shown inFIG. 8a, a bushing106can have a segment802with a plurality of longitudinal slots804. In some embodiments, a segment802can be extruded radially such that the surfaces of a bushing106radially adjacent to longitudinal slots804bulge outward. As shown inFIG. 8a, a segment802can have a bulbous configuration, but in other embodiments can have any other known and/or convenient geometry.

FIG. 8bdepicts an alternate embodiment of the present device as shown inFIG. 8a, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 9adepicts another embodiment of the present device, in which a bushing106can have a circumferentially varying wall thickness. In such embodiments, the inner surface of a bushing106does not substantially align with the outer surface relative to the central longitudinal axis of a bushing106. An opening902can be non-concentric with the outer surface of a bushing106.

FIG. 9bdepicts an alternate embodiment of the present device as shown inFIG. 9, in which a bushing106can have a longitudinal slit202. In some embodiments a longitudinal slit202can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106.

FIG. 10adepicts another embodiment of the present device, in which a bushing106can have a circumferentially varying wall thickness. In such embodiments, the inner surface of a bushing106does not substantially align with the outer surface relative to the central longitudinal axis of a bushing106. An opening902can be non-concentric with the outer surface of a bushing106. As shown inFIG. 10a, this configuration can create a bushing106with a crescent-shaped cross-section.

FIG. 10bdepicts an alternate embodiment of the present device as shown inFIG. 10a, in which a bushing106having a crescent-shaped cross section can have a longitudinal gap1002. In some embodiments a longitudinal gap1002can run along the entire length of a bushing106, but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing106. A longitudinal gap1002can be located at the point of least thickness of the cross-section or at any other known and/or convenient location.

In use, a bushing106can be placed into a hole on a rocker arm support102. A bolt104can be placed through a bushing106and then through a rocker arm support102. Tightening down a bolt104can push a bushing106down into the hole, filling the clearance space between a bolt104and a rocker arm shaft105. This can mitigate or eliminate the motion of a rocker arm shaft105against a bolt and the tapping sound that creates. In some embodiments, the present device can also dampen the sound of closing valves in the engine and decrease unwanted noise.