| 摘要 |
PURPOSE:To prevent a valve seat from blow by a structure wherein seat material with higher corrosion resistance than valve base material is equipped over the outer peripheral side of the valve seat and at the same time seat material with higher hardness than valve base material over the inner peripheral side. CONSTITUTION:Corrosion-resisting material 14 containing Ni base material, which is higher corrosion-resistant that valve base material 12, as a base is equipped over the whole outer peripheral surface of a valve. In addition, very hard material 15 containing Co base material, the hardness of which is higher than that of the valve base material 12, as a base is equipped over the whole inner peripheral surface of a valve seat 13 along the periphery of a valve head. Thus, the outer peripheral surface of the valve, which is exposed to high temperature and corrosive gas due to the burning of power quality oil, is made to be hard to the high temperature corrosion. Further, the application of the very hard material at the inner peripheral surface, on which the severe fixing by pressure is applied, makes the formation of indentation difficult. Accordingly, the blow by through the valve seat can be prevented. |
