| 摘要 |
PURPOSE: A hollow poppet valve is provided to offer an extremely lightweight hollow poppet valve for an internal combustion engine, which has high fatigue strength and durability in a welded part between the periphery of the enlarged part of a valve shaft and a valve cap member. CONSTITUTION: The hollow poppet valve(31) having a funnel-like enlarged part(17) having a certain wall thickness and a downwardly extended cylindrical part(33) is equipped with a valve cap member(15) having a valve contact surface. The inner side surface of the periphery of the valve cap member(15) and the outer side surface of the enlarged part(17) are positioned near to each other, an axially extended boundary surface is formed between the inner side surface and the outer side surface, and a welding part is formed on the boundary surface. The axial length of the welding part is at least 1.1 times the thickness of the enlarged part(17), and the inner side radius of curvature of the periphery of the enlarged part(17) is 0.3 times or more the thickness of the enlarged part(17).
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