TIGHTENING STRUCTURE FOR CYLINDER HEAD BOLT

摘要

A cylinder head bolt inserted into a cylinder head is threadingly engaged with an engine casing comprised of a cylinder and a crankcase to tighten the cylinder head and the engine casing firmly together. Between a rotation operating part, which is provided in a head of the cylinder head bolt, and an upper surface of the cylinder head, a plain washer and a spring member placed thereabove are interposed. The spring member is capable of exerting an axially acting spring force. A first frictional resistance between the rotation operating part and the spring member is so chosen to be lower than a second frictional resistance between the spring member and the plain washer and a third frictional resistance between the plain washer and a bearing surface on the cylinder head.

主权项

1. A tightening structure for a cylinder head bolt to tighten a cylinder head to an engine casing by threadingly engaging a cylinder head bolt, which has been inserted through the cylinder head, into the engine casing including the cylinder and a crankcase, the tightening structure comprising:
a plain washer; and a spring member placed over the plain washer to exert a spring force in an axial direction of the bolt, the plain washer and the spring member being disposed between a rotation operating part provided in a head of the cylinder head bolt and an upper surface of the cylinder head, wherein a first frictional resistance between the rotation operating part of the cylinder head bolt and the spring member is chosen to be lower than a second frictional resistance between the spring member and the plain washer and a third frictional resistance between the plain washer and a bearing surface defined on the upper surface of the cylinder head.