Analysis of automotive transmission gearbox synchronizer wear due to torsional vibration and the parameters influencing wear reduction

Abstract

Synchronizers are the heart for the manual transmission, automated manual transmission and dual clutch transmission. The synchronizers match the speed of the target gears during gear shifts. Downsizing the high-power density engine develops higher angular accelerations. Higher angular accelerations create torsional vibrations and are detrimental to the life of the synchronizers. The synchronizer rings can move freely in the available space due to torsional vibration. The synchronizers which experience higher angular acceleration collide with the surrounding parts and wear out. The wear of synchronizer carbon liner reduces the wear gap to zero. The zero-wear gap hampers the synchronizer functionality and leads to gear clash. This paper presents the impact of angular acceleration on the life of carbon synchronizer ring and the parameters which are influencing to overcome the failure are studied. A bench test set-up was developed to simulate the vehicle level angular accelerations. The bench test results show direct correlation with the life of the synchronizer on the vehicle. Torsional vibration dampening using clutch size, oil viscosity, guiding of synchronizer ring, and oil volume are studied. The synchronizer carbon liner wear reduction is studied and validated with different bench and vehicle level tests.