Patent ID: 6250271
Filing Date: 2001-06-26
Classification: F01L

Abstract:
A decompression device of a four-stroke-cycle internal combustion engine, comprising:a cam shaft having an exhaust cam for driving an exhaust valve to open and formed with an axial hole;an oil pressure chamber formed in said axial hole to be supplied with pressure oil;a decompression shaft fitted in said axal hole to be positioned at one of a first position and a second position corresponding to oil pressure in said oil pressure chamber;a decompression pin which drives said exhaust valve to open in compression stroke of said engine when said decompression shaft is positioned at said first position and stops to drive said exhaust valve when said decompression shaft is positioned at said second position; andan oil pressure control valve by which oil pressure in said oil pressure chamber is set to a pressure for positioning said decompression shaft at said first position when rotational speed of said engine is below a specific starting rotational speed or to a pressure for positioning said decompression shaft at said second position when rotational speed of said engine is above said specific starting rotational speed.