自動車用ATにおける分数調波振動に関する基礎実験および理論解析

Abstract

A torque converter is an element to transfer torque from the engine to the gear train in an automatic transmission vehicle. There is a damper spring on the lock-up clutch in the torque converter that reduces the amplitude of vibration caused by engine combustion. The damper is designed using a piecewise-linear spring with three stages in order to address a problem of space limitations. However, the damper causes a nonlinear vibration called subharmonic vibration of order 1/2. The frequency of the subharmonic vibration is half of the engine forced vibration frequency. In this study, in order to clarify the occurrence mechanism of the subharmonic vibration caused by the non-linearity of a piecewise-linear spring, fundamental experiments and numerical analysis were performed. The experimental setup is single-degree-of-freedom system that has two stiffness stages and the numerical analysis was performed under same condition as the experiment by using shooting method. According to the results of the experiments and numerical analysis, it was found that the subharmonic vibration occurs when the excitation frequency is near the twice of the resonance frequency and the equilibrium point is around a switching point of spring stiffness, and the smaller stiffness ratio and larger damping can suppress the subharmonic vibration. Also, the experimental and analytical results were well agreed with each other and the correctness of the experimental results were confirmed.