US Patent 9618105 Fluid power transmission device

A torque converter includes a torque converter body, a lock-up device, and a dynamic damper. The lock-up device includes an output plate coupled to a turbine. The dynamic damper is fixed to the output plate of the lock-up device, and is configured to attenuate variation in speed of rotation from the engine. The dynamic damper includes a base plate, an inertia unit, and an elastic unit. The base plate is fixed to the output plate. The inertia unit is movable relative to the base plate in a rotational direction. The elastic unit exerts nonlinear torsional characteristics, and elastically couples the base plate and the inertia unit in the rotational direction.