Lock-up clutch device

Abstract

In a torque converter equipped with a lock-up clutch device, a friction member is put on either one of a front cover and a lock-up piston which are to be brought into contact. On the front cover, coupling members are welded for coupling with an engine. Owing to welding distortion, convex portions are generated on a friction face. Thus, when the friction member is put on either side of the front cover and clutch piston, if relative rotation slippage occurs therebetween, a positive pressure and a negative pressure are produced in front of and behind each convex portion, which leads to the stick/slip. This invention gives grooves 71 each exceeding the range of a welding portion 61 of the coupling member 6 which are formed on the friction face of the friction member 7, which realizes balancing in a change in pressure.

Dependencies are inferred from the claim text.