Lock-up device for torque converter

A lock-up device for a torque converter, the lock-up device being disposed between a front cover and a turbine in order to transmit and cut a torque, the lock-up device comprising:

• a piston being disposed between the front cover and the turbine, the piston being axially slidable by operating oil;
• a clutch part being configured to allow or cut transmitting the torque between the front cover and the turbine by actuating the piston;
• a first hydraulic chamber to which the operating oil for actuating the piston is supplied;
• a second hydraulic chamber to which the operating oil for actuating the piston is supplied, the second hydraulic chamber being formed independently from the first hydraulic chamber on the same side as the first hydraulic chamber with reference to the piston, the second hydraulic chamber not being in direct fluid communication with the first hydraulic chamber;
• a first hydraulic port being disposed to supply the operating oil to the first hydraulic chamber;
• a second hydraulic port being disposed to supply the operating oil to the second hydraulic chamber, the second hydraulic port being provided independently from the first hydraulic port;
• and
• a tubular member fixed to a turbine-side lateral surface of the front cover, the piston being slidably supported by an outer peripheral surface of the tubular member,
• the first hydraulic chamber being configured between the front cover and the piston, the lock-up device further including a compartment plate being disposed between the first hydraulic chamber and the second hydraulic chamber, the compartment plate forming the second hydraulic chamber between the compartment plate and the piston, and
• the compartment plate being immovably fixed to the outer peripheral surface of the tubular member.