Lock-up device for torque converter

A lock-up device for a torque converter disposed between a front cover connected to an engine output side and a turbine, comprising:

• an input member to which a torque is input from the front cover through a friction force;
• an output member connected to the turbine to be integrally rotated and provided to be relatively rotatable with respect to the input member;
• a first elastic member and a second elastic member elastically connecting the input member and the output member in a rotational direction, respectively;
• and
• a dynamic damper directly installed to the output member, the dynamic damper including an inertial mass body disposed to be in close contact with the output member so as to be relatively rotatable with respect to the output member, and a third elastic member elastically connecting the inertial mass body and the output member with respect to the rotational direction,
• wherein the inertial mass body includes:
• a first mass plate disposed in close contact with a first side surface of the output member;
• and
• a second mass plate disposed in close contact with a second side surface of the output member and integrally rotating with the first mass plate,
• wherein the first elastic member is disposed outside in a radial direction with respect to the second elastic member, and
• wherein the dynamic damper is disposed between the first elastic member and the second elastic member in the radial direction, and
• wherein the first mass plate and the third elastic member are disposed to entirely overlap the first elastic member with respect to a rotation axis direction when viewing in the radial direction.