Internal-combustion engines – Poppet valve operating mechanism – Plural valve trains – single actuator
Reexamination Certificate
1999-08-31
2001-05-29
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Plural valve trains, single actuator
C123S090400, C123S090420, C123S090450, C074S559000
Reexamination Certificate
active
06237552
ABSTRACT:
TECHNICAL FIELD
The present invention relates to internal combustion engines. More particularly, the present invention relates to a rocker arm for controlling the delivery of air or fuel to an internal combustion engine.
BACKGROUND ART
One example of a known internal combustion engine is contained in U.S. Pat. No. 5,743,219, incorporated by reference herein. At the heart of this engine is a plurality of cylinders that house pistons. The cylinders are in communication with air and fuel intakes. Incoming air and fuel is compressed and ignited in a reciprocal fashion that drives the pistons which, through known means, drive the motorcycle's wheel. The timing and amount of fuel and air entering the cylinder is typically controlled by valves. Similarly, valves control the release of exhaust gases after combustion. Operation of these valves may be controlled by cams that selectively open and close the valves during the cam's rotation. The cam profile determines the period and amount of valve displacement. Often the cam is placed in operative contact with a rocker arm that acts as an intermediary between the cam and valve. At times, a single cam uses a rocker arm to actuate more than one valve. The rocker arm is pivotally mounted above and in contact with one or more valves, and a cam rides along the opposite surface of the rocker arm depressing and releasing the rocker arm as it rotates. In turn, the valves are depressed and released by the rocker arm. Typically, rocker arms are spring mounted to maintain contact with the cam.
Known rocker arms for motorcycles employ a raised striking surface made of polished chrome at the point of contact between the cam and rocker arm. A cam located above the striking surface engages the polished chrome striking surface. As the cam rotates, its surface slides across the string surface, creating significant frictional forces. The surface contact between the cam and rocker arm abrades these surfaces and produces heat, shortening the operative life of each component. The heat causes the component materials to expand, increasing the functional forces and wear. Due to the cyclic motion of the cam, the amount of contact increases with engine speed. At elevated engine speeds, the wearing of the polished chrome surface forms minute beads or balls of chrome material on the surface of the striking plate. These beads dramatically abrade the cam and striking plate surfaces in a short period of time. This abrasion significantly shortens cam and rocker arm life.
In further detriment, the frictional forces between the plate and cam sap the engine's usable horsepower. The force needed to rotate the cam is related to the frictional forces because these must be overcome to rotate the cam. Since more horsepower is committed to rotating the cam, less horsepower is available to drive the motorcycle and, thus, the motorcycle suffers reduced performance.
Therefore, there is a need for a rocker arm that improves cam and rocker arm life and reduces the frictional forces between the cam and rocker arm.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a rocker arm that reduces the frictional contact between the cam and rocker arm.
It is another object of the present invention to provide a rocker arm with improved operational life.
It is a further object of the present invention to provide a rocker arm that lengthens the operating life of a cam in operational contact with the rocker arm.
The foregoing and other objects of the present invention, which shall become apparent as the detailed description proceeds, are achieved by a rocker arm comprising two-spaced side members having a pivot portion, a middle portion, and a valve portion, the side members each defining a downwardly extending tappet hole located generally centrally within the valve portion, the middle portion of each side member defining a bearing hole, and each of the pivot portions defining a pivot hole; a first web portion extended between the side members and the valve portion and a second web portion extending between the side members at the pivot portion defining a recess therebetween at about the middle portion; a pin bearing located within the bearing holes passing through the recess; and an annular striking member located within the recess rotatably engaging the pin bearing.
The present invention further provides a rocker arm assembly comprising a pair of spaced side members having a valve portion, a middle portion, and a pivot portion, the side members joined by a web; a gusset portion extending downwardly from the middle portion of the side members defining a bearing hole penetrating the gusset portions; wherein the web at the valve portion extends downwardly defining a pair of valve recesses linking either side of the web and bounded by a lower surface of the side members at the valve portion and a front surface of the gusset portion; wherein the web located at the pivot portion extends downwardly adjacent to a rear-face of the gusset portion; wherein a pivot portion defines a pivot hole penetrating the web and the pivot portion; a pin bearing located within the bearing hole; and an annular striking member surrounding and rotatably engaging the pin bearing, wherein the striking member is located at the middle portion between the side members; and a rounded can located above and operatively engaging the striking member.
The present invention further provides a rocker arm for actuating valves in an internal combustion engine comprising a valve portion, a middle portion, and a pivot portion; a pivot hole formed within the pivot portion; and a striking member rotatably mounted within said middle portion.
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Lo Weilun
Renner Kenner Greive Bobak Taylor & Weber
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