| 摘要 |
A plurality of head bolt holes (8) is formed in the top part (4) of a cylinder block (1) of an engine at prescribed intervals about the peripheries of cylinder bores (2). Female threads (8b) are formed in the head bolt holes (8) and wall buildups (9) are formed on side walls of the cylinder block (1) around the female threads (8b) respectively. Axial tension transmission members (10) are also formed on the cylinder block side walls between the wall buildups (9) so as to interconnect adjacent wall buildups (9). The axial tension produced in the female threads upon tightening of the head bolts is transmitted not only to the vicinities of head bolt holes (8), but also to intermediate areas (12) between adjacent head bolt holes, via the wall buildups (9) and axial tension transmission members (10). Thus, the top face (5) of the cylinder block (1) is uniformly pressed against the mating bottom face of the cylinder head even if the cylinder block is made of a material with small Young's modulus such as aluminum.
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