Development of New Groove Design for Reduction of Drag Torque or Spin Loss of Disengaged Wet Clutches in the High Speed Region

The typical graph of a drag torque or spin loss vs. speed of disengaged wet clutch of automotive transmission shows 4 types of trends. First one is increasing until a peak level, next decreasing to the lowest level, next saturating or being no change, and last again increasing. If the absolute value of drag torque at high speed (6000-20,000rpm) is high, the possibility of fluttering of friction disk, chipping, burning and delamination of friction materials will be high. Moreover, the efficiency of a transmission will be dropped and the life of it become shorter. Therefore, it is important to understand the physics behind the torque jump up at high speed. In our previous study, we investigated the possible reasons of torque jump up at high rotation speed. In this paper, we have extended our previous study and developed new groove design to reduce the drag toque in the high speed range. Result shows that a significant amount of drag torque in the high speed range can be reduced by a new groove design friction disk.