Abstract
We herein analyze the occurrence mechanism of the subharmonic vibration of order 1/2 due to the torsional forced vibration caused by engine explosions in an automatic transmission powertrain. In the torque converter, a damper with a piecewise-linear spring is used to reduce the forced vibration, and the subharmonic vibration occurs when the spring restoring torque characteristics approach the switching point. The powertrain is modelled by a multiple degree-of-freedom system as an actual vehicle, and the mechanism of the subharmonic vibration was clarified. In the present paper, the suppressive effects of the damping at the damper and the spring constant ratio between the neighboring springs are also discussed. The results indicate that larger damping can suppress the occurrence of the subharmonic vibration and that reducing the spring constant ratio between neighboring springs can reduce the occurrence of the subharmonic vibration.
KEYWORDS – Automatic transmission, Powertrain, Damper, Nonlinear vibration, 1/2 Subharmonic vibration