AUTOMATIC COMPRESSION RELEASE APPARATUS FOR AN INTERNAL COMBUSTION ENGINE

摘要

An internal combustion engine is provided with a mechanism to release engine compression at low speeds thereby facilitating starting of the engine. The engine has an exhaust valve which is operated by a valve lifter following a cam surface. A cam pin is positioned within a seat in that cam surface in a manner which allows the pin to rotate. A drive pin extends orthogonally from the cam pin and passes through an aperture within a flyweight. The flyweight causes a rotation of the cam pin in response to engine speed. At relatively low engine speeds an eccentric portion of the cam pin extends above the cam surface so as to engage the valve lifter producing an opening of the exhaust valve during the compression portion of the engine cycle. At higher engine speeds the cam pin is rotated so that the eccentric portion of the cam pin no longer extends above the cam surface so that the exhaust valve is not opened during the engine compression. This operation produces a release of the compression at lower engine speeds. The compression release mechanism is designed so that the noise attributable to the valve lifter engaging the cam pin will be minimized.