Numerical Analysis of Flow in a Lock-Up Clutch of an Automotive Torque Converter

The flow through a single-plate lock-up clutch in an automotive torque converter was numerically investigated using a CFD code. The flow was computed under various clearances between the lock-up piston and the cover-converter. The stable location of the lock-up piston was determined so that the thrust acting on the lock-up piston became zero. The computation results showed that the fluid flowed outwards in the narrow channel between the lock-up clutch facing and the cover-converter, whereas the flow reversed inwards near the lock-up piston surface upstream and downstream of the narrow channel in most cases. Along the outer surface of the axial flow channel near the exit, the flow also reversed far upstream of the channel. The computation results well predicted the stable position of the lock-up piston. It is noted that the sharp increase in clearance in the coupling range can be clearly captured with the method.