Patent ID: 7222706

Claim:
A lockup device for use in a hydraulic torque transmission device, the lockup device including a front cover having a friction surface, an impeller fixed to the front cover to define a fluid chamber filled with a working fluid, and a turbine arranged in the fluid chamber and opposed to the impeller, the lockup device comprising: a friction plate having a frictional coupling portion adjacent to the friction surface, and being configured to provide torque to the turbine; a disk-like piston being arranged between the front cover and the turbine, said piston having a pressing portion arranged on a side of said frictional coupling portion remote from the friction surface, and being axially movable in response to a change in hydraulic pressure; a piston coupling mechanism being configured to couple unrotatably and axially movably said piston to the front cover; a seal mechanism being configured to seal a radially inside portion of said piston on a side of said piston axially opposite the front cover, said piston coupling mechanism being arranged radially inside said seal mechanism and axially between said seal mechanism and the front cover; and a damper mechanism being arranged in an axial space between said the front cover and the turbine, and located radially between said friction plate and said seal mechanism.