ENGINE BLOCK, INTERNAL COMBUSTION ENGINE WITH ENGINE BLOCK, ENGINE BLOCK CASTING METHOD, ENGINE BLOCK CASTING DEVICE, AND CAST PIN

摘要

PROBLEM TO BE SOLVED: To achieve both the suppression of a reduction in the strength of an engine block and the suppression of a pressure fluctuation in a crankcase while reducing manufacturing cost.SOLUTION: Since through-holes 28a, 28b, 28c, and 28d are formed using a cast pin 70 having an intermittent cast gradient, it is possible to suppress an inside diameter difference between the first through-hole 28a and the fourth through-hole 28d, particularly an inside diameter difference between a small end hole diameter of the first through-hole 28a and a large end hole diameter of the fourth through-hole 28d as compared with a configuration in which the through-holes are formed using a cast pin having a continuous cast gradient. It is thereby possible to suppress the first through-hole 28a from being made unnecessarily small in size or the fourth through-hole 28d from being made unnecessarily large in size. As a result, both the suppression of a reduction of strength and the suppression of a pressure fluctuation can be achieved. Notably, special mechanical machining can be dispensed with and manufacturing cost can be reduced since the through-holes 28a, 28b, 28c, and 28d are formed by cast.