| 摘要 |
A hollow poppet valve exhibits improved thermal conductivity obtained by extending a small-diameter hollow section, which is formed within a valve shaft, to the bottom surface of a large-diameter hollow section, which is formed within a valve umbrella section. A hollow poppet valve (10) is configured in such a manner that a truncated circular conical large-diameter hollow section (S1), formed within an umbrella section (14), connects to a small-diameter hollow section (S2), which is formed within a shaft section (12). A pipe-like partition wall (15), which extends the hollow section (S2) to the bottom surface (the reverse side of a cap (18)) of the hollow section (S1), is provided within the hollow section (S1), and the hollow sections (S1, S2) are separated from each other. The hollow sections (S1, S2) are filled with inert gas and a cooling material (19), respectively. Inertia force which acts on the cooling material (19) in the hollow section (S1) during the opening and closing operation of the valve (10) is utilized only to form a tumble flow, and a powerful tumble flow is formed smoothly. Part of the heat of a valve umbrella surface (18a) is directly transferred to the shaft section (12) through the cooling material (19) within the hollow section (S2), enhancing the thermal conductivity of the valve (10). |
