Engine lubrication system

Abstract

An engine lubrication system is provided which has an oil pump for supplying lubricating oil from an oil pan to an area that is to be lubricated, the oil pump being positioned outside the oil pan and driven by a camshaft. An oil passage formation member fitted to the lower face of an engine block so as to be housed in the oil pan, comprises an oil inlet passage for taking in oil from the oil pan to the oil pump and a relief valve for discharging excess oil discharged by the oil pump via an oil supply passage. When the relief valve opens, the excess oil is not directly discharged to the oil pan but is returned to the oil inlet passage from the oil supply passage via a connecting path. The space required for housing a vertical engine, and in particular in the vertical direction, can thus be reduced and the formation of bubbles in the oil inside the oil pan due to the oil discharged by the relief valve through the oil supply passage, can be prevented.

Dependencies are inferred from the claim text.