着座衝撃をもつエンジンバルブに付けられた不減衰1体系弁ばねのサージングを抑制するバルブリフトの設計法の提案

抄録

This study investigates a valve lift designed to prevent valve spring surging in a valve train operating at a constant speed, typical of series-type hybrid engines. The paper outlines a method for designing a cam function that mitigates surging in the primary mode, which is the predominant vibration in an undamped linear valve spring, even during discontinuous speed changes when the valve body seats. The proposed cam function is a finite-time settling function using the solution of a two-point boundary value problem composed of half-odd integer trigonometric functions. By varying the parameter p, a countably infinite number of cam trajectories can be generated, and all of which serve as surging preventive cam functions. The cam function can be tailored to different rise times and collision velocities. By setting parameter p to 1 or employing an infinite series, a valve lift with a wave number of 1 and minimal concavities can be achieved. Additionally, the convergence of the coefficients in the infinite series is found to be important for the valve lift design. Utilizing these valve lifts is expected to significantly reduce engine energy loss due to friction between the cam and the tappet.