Lubricating system for horizontal cylinder overhead valve engine

摘要

A lubricating system for an internal combustion engine is disclosed. This system includes a pair of passages formed between a crank chamber for reserving oil and an air-oil separating chamber accommodating a mechanism for actuating overhead valves. The pair of passages are constituted by a breather passage formed in the upper portion of a cylinder and the oil-returning passage formed in the lower portion of the cylinder. The breather passage has a valve for allowing a fluid to pass solely toward the air-oil separating chamber and a large oil-circulating resistance is imparted to the fluid flowing toward the air-oil separating chamber through the oil-returning passage, thereby circulating an oil mist in one direction only by using the reciprocal motion of each piston. Even when the engine is inclined, oil is prevented from flowing back from the crank chamber to the separating chamber through the oil-returning passage.