Patent ID: 7980370

Claim:
A lockup device for a hydraulic torque transmission device having a front cover supplied with a torque, an impeller fixed to the front cover and forming a fluid chamber filled with a working fluid, and a turbine opposed to the impeller, the lockup device being arranged in a space between the front cover and the turbine to couple mechanically the front cover to the turbine, the lockup device comprising: a piston arranged rotatably and axially movably with respect to the turbine and being axially movable according to a pressure of the working fluid; a clutch member having a frictional coupling portion arranged axially between the piston and the front cover for frictional engagement with the piston and the front cover; and a damper mechanism elastically coupling the clutch member and the turbine together in a rotating direction, the clutch member having an annular first plate configured to engage frictionally with the front cover, and an annular second plate arranged between the first plate and the piston and configured to engage frictionally with the piston, the first and second plates being arranged to allow the working fluid to flow between the first and second plates from a radially inner side of the first and second plates, radially outer portions of the first and second plates being fixed to each other, when the lockup device is disengaged, a first passage through which the working fluid flows from the radially inner side of the first and second plates to a space formed axially between the front cover and the frictional coupling portion is formed between the first and second plates and a second passage through which the working fluid flows from the radially inner side of the first and second plates to a space formed axially between the piston and the frictional coupling portion is formed between the first and second plates.