| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology for easily and effectively implementing improvement of the quality, strength and coolability of a cylinder block.SOLUTION: Connection wall parts 64, 65 for connecting a cylinder bore wall part 66 having a cylinder bore 66a and side wall parts 62c, 62d are formed in a block water jacket BWJ. When cast-molding a cylinder block 6, the connection wall parts 64, 65 are molded over the whole area in the depth direction of the block water jacket BWJ. After cast-molding the cylinder block 6, by linearly scraping off upper portions of the connection wall parts 64, 65 with use of an end mill EM having a diameter that is almost the same with the width dimension of the block water jacket BWJ, flat portions 30 are formed on the block water jacket BWJ. The flat portion 30 is formed such that a central angle having the vertex of the angle in the center of the cylinder bore 66a is within a range of 25° to 35°, preferably 30°.SELECTED DRAWING: Figure 7 |
