| 摘要 |
PURPOSE:To increase the heat-load resisting properties of a four-valve aluminum cylinder head, by casting a cylindrical steel member in an ignition plug hole formed at the center portion of the cylinder head in the manner that it is surrounded by four valves. CONSTITUTION:A hole for inserting therein an ignition plug 1 is formed at the central portion of an aluminum cylinder head 2, and intake-valve seats 6-1, 6-2 and exhaust-valve seats 7-1, 7-2 are disposed around the ignition plug hole. Further, a cylindrical steel member 4 is fitted in said ignition plug hole by way of casting. With such an arrangement, the heat-load resisting properties of the cylinder head 2 can be increased by the steel member 4 having a higher rigidity than the main body of aluminum located around the ignition plug hole and between the valves even if spacing of the ignition plug hole from the valve seats is decreased by making the cylinder head in a four-valve type. |
