Patent ID: 6834643
Filing Date: 2004-12-28
Classification: F01M

Abstract:
A breather structure for an overhead-valve internal combustion engine in which a cylinder bore is formed in a cylinder block coupled to a crankcase which rotatably supports a crankshaft, a camshaft housing chamber which houses a camshaft for performing an open/close driving of an intake valve and an exhaust valve which are arranged in a cylinder head is formed between the cylinder head which is coupled to the cylinder block, a driving force transmission chamber which is arranged at the side of the cylinder bore is formed in the crankcase, the cylinder block and the cylinder head such that a driving force transmission member which transmits a rotational driving force of the crankshaft to the camshaft is housed in the driving force transmission chamber, and a breather chamber which is arranged below the camshaft housing chamber and at the side of the cylinder bore and the driving force transmission chamber is formed such that the breather chamber extends between the cylinder block and the crankcase comprising:a breather inlet passage including an upper end thereof in communication with an inside of the camshaft housing chamber and a lower end thereof in communication with the breather chamber at a position corresponding to a mating face between the cylinder block and the crankcase is arranged in the cylinder block such that the breather inlet passage extends vertically; and an oil discharge hole being in communication with a lower portion of the inside of the breather chamber and arranged in the crankcase.