Investigation on Torque Jump Up and Vibration at High Rotation Speed of a Wet Clutch

Reduction of the drag torque and longevity of the clutch assembly are the most important factors for vehicle transmission improvement. The decreasing trend of the drag torque with speed after its peak is a common characteristic of the clutch assembly. Several theoretical models have been presented by the researchers describing the drag torque characteristics at lower clutch speed. However, very little study has been made on the drag torque behavior at very high clutch speed (6000∼10000+ rpm). The alarming jump of the drag torque at high speed operating condition remains unexplained till date. In this paper, we investigated the possible reasons of torque jump up at high rotation speed and solution to overcome this problem. We presented an analytical correlation of torque jump up with the excessive decrease of local static pressure and assumed that vacuum formation is the possible reason of high speed torque rising and associated vibration. Result shows that when the separator plates are free, a remarkable torque jump is observed. However the drag torque jump up at higher speed can be eliminated by fixing the separator plates by some means.