INTAKE AND EXHAUST VALVE FOR INTERNAL-COMBUSTION ENGINE

摘要

PURPOSE:To improve the cooling effect of a stem portion by providing a spiral groove in the inner periphery of a valve guide to open the lower and upper portions of the spiral groove respectively to an oil supply hole and an upper space of a cylinder head. CONSTITUTION:A valve guide 21 is provided on the inner periphery with a spiral oil groove 25 the lower portion of which opens to an oil hole 11 of a cylinder head 1. The other end of the spiral groove provides an annular groove 18 engraved on the inner periphery of the lower portion of the valve guide 21 and opens to an upper space of the cylinder head 1 through a knotch 20 engraved on a communicating hole 23 and the outer periphery of the valve guide 21. The spiral oil groove 25 has a large surface area and path length so that a valve stem 4a can be sufficiently cooled.