Hydraulic power transmission device

A hydraulic power transmission device for transmitting power from an engine to a transmission via a fluid, the hydraulic power transmission device comprising:

• a front cover;
• a fluid coupling main body including a turbine provided in a manner capable of rotating integrally with an input shaft of the transmission, the fluid coupling main body for transmitting power from the engine to the transmission via the fluid;
• a lock-up device provided between the front cover and the turbine, the lock-up device including a clutch portion and an output-side member, the clutch portion for transmitting or cutting off power from the front cover, the output-side member for receiving power from the clutch portion, the output-side member coupled to the turbine;
• and
• a dynamic damper for attenuating rotational speed fluctuation from the engine, the dynamic damper including a base plate, an inertial body and an elastic unit, the base plate fixed to the output-side member of the lock-up device, the inertial body capable of moving in a rotation direction relative to the base plate, the elastic unit capable of generating a variable hysteresis torque according to a relative speed difference between the base plate and the inertial body, the elastic unit coupling the base plate and the inertial body elastically in the rotation direction.