Four-cylinder crankcase for internal combustion engine, has coated cylinder borehole that comprises chamfer at joint surface to cylinder head, where chamfer is double chamfer consisting of two chamfer parts

摘要

The crankcase (1) has a coated cylinder borehole (2) that comprises a chamfer (4) at a joint surface (3) to a cylinder head, where the chamfer is a double chamfer consisting of two chamfer parts (4a, 4b). The chamfer parts are inclined with respect to the cylinder borehole at angles (alpha, beta) in the range of 30-60 degree and 5-45 degree respectively. The chamfers are formed by milling process in a single manufacturing step. The crank case is made of light alloy such as under-eutectic aluminum silicon alloy.