Patent ID: 6230680
Filing Date: 2001-05-15
Classification: F01M

Abstract:
An oil pump and control check valve assembly for a four stroke cycle motorcycle engine having a crankcase, a crankshaft with bearings, and tappets or valve guides at the upper end of combustion cylinders, comprising:an oil pump housing incorporating a feed portal, a high pressure delivery portal, and a high pressure oil pump between said portals;a low pressure return oil pump also incorporated in said housing,a delivery check valve mounted in said high pressure delivery portal having a predetermined cracking pressure,an upper delivery conduit delivering oil from said delivery check valve to the tappets at the upper end of the motorcycle engine,means forming a passage in said oil pump housing connecting the high pressure delivery portal to a second check valve having an intermediate cracking pressure,a lower delivery conduit connecting said second check valve to the crankshaft bearings of said motorcycle engine,a third relief check valve connecting said lower delivery conduit to the oil pump's feed portal and having a cracking pressure higher than said intermediate cracking pressure,a return oil conduit connecting the engine's crankcase to said low pressure return oil pump,and an external oil tank having an intake conduit delivering oil to said tank from said low pressure return oil pump, and having an oil feed conduit delivering oil from said tank to the feed portal of said oil pump housing.