Patent ID: 7147090

Claim:
A hydrodynamic torque transmitting device, comprising: an input side front cover; an impeller being coupled to the front cover to form a fluid chamber therewith; a turbine having a turbine hub, and a vane portion disposed inside the fluid chamber and opposite the impeller; a piston having a disk-shaped main body, a frictional coupling portion disposed on an outer peripheral portion of the main body being configured to couple frictionally with the front cover, and a support portion being configured to support the turbine in the axial direction when the piston moves toward the front cover, the support portion having a flat surface axially contacting the turbine and a cylindrical portion extending axially from an innermost peripheral edge of the piston, the flat surface and the cylindrical portion being arranged to extend from the innermost peripheral edge, the piston being disposed to divide a space between the front cover and the turbine into a front chamber on a front cover side and a rear chamber on a turbine side and being configured to move toward and away from the front cover by a pressure differential created by fluid between the front chamber and rear chamber; and an elastic coupling mechanism being arranged at an outer peripheral portion of the turbine and the piston to couple the turbine and the piston, the turbine hub and the front cover respectively including opposing portions being mutually opposed to each other across a space in an axial direction, and the opposing portions being configured to maintain a gap in the axial direction therebetween to prevent a load from the turbine being applied to the front cover when the piston moves to a position closest to the front cover.