Patent ID: 7263960
Filing Date: 2007-09-04
Classification: F01L,F02N

Abstract:
1. An engine decompression system for an engine having a valve operating cam shaft and a valve operating cam for opening and closing an engine valve, said engine decompression system comprising: a decompression cam shaft mounted on the operating cam shaft and a decompression cam mounted on the decompression cam shaft, wherein the decompression cam shaft rotates between an operating position in which a decompression cam projects above a base face of the valve operating cam for slightly opening the engine valve during an engine compression stroke, and a release position in which the decompression cam is withdrawn beneath the base face for allowing the engine valve to close; and a centrifugal mechanism connected to the decompression cam shaft to maintain the decompression cam shaft at the operating position during engine starting rotational region, and to rotate the decompression cam shaft to the release position in a normal running region, wherein in a complete combustion rotational region between the engine starting rotational region and the normal running region, the decompression cam shaft is maintained at a substantially constant middle position in which the projection height of the decompression cam above the base face is less than the projection height at the engine starting rotational region, and greater than the projection height at the normal running region.