Patent ID: 7096850
Filing Date: 2006-08-29
Classification: F01L,F02B

Abstract:
1. A four-cycle combustion engine which comprises: a valve operating mechanism including a valve drive unit mounted on a cylinder head for driving intake and exhaust valves, and a drive transmitting unit for transmitting a rotary drive of a crankshaft, drivingly coupled with a piston, to the valve drive unit; a valve chamber accommodating therein the valve drive unit and communicated with an intake port capable of being selectively opened or closed by the intake valve; an intake passage for introducing into the valve chamber an air-fuel mixture containing lubricant oil; a first passage accommodating therein the drive transmitting unit and communicating between the valve chamber and a crankcase chamber; and a second passage communicating between the crankcase chamber and the valve chamber; wherein said valve chamber, said first passage, said crankcase chamber and said second passage cooperate with each other to define a circulating passage through which a portion of the air-fuel mixture from the intake passage is circulated as a result of a reciprocating motion of the piston.