Breather structure of overhead-valve internal combustion engine

摘要

An overhead-valve internal combustion engine with a breather chamber arranged below a camshaft housing chamber for housing the camshaft and formed between a cylinder head and a cylinder block. A driving force transmission chamber is formed between a cylinder and a crankcase. Thus, the discharge of oil from the breather chamber is performed smoothly so as to enhance the vapor-liquid separation performance. A breather inlet passage has an upper end thereof in communication with an inside of a camshaft housing chamber and a lower end thereof in communication with a breather chamber at a position corresponding to a mating face between a cylinder block and a crankcase is formed in the cylinder block such that the breather inlet passage extends vertically. An oil discharge hole is in communication with a lower portion of the inside of the breather chamber and is formed in the crankcase.