Patent ID: 7401464

Claim:
An energy regeneration system for machinery comprising: a fluid pressure actuator adapted to operate by being supplied or discharging fluid; a first displacement variable regenerating fluid pressure motor in a discharge flow path for fluid discharged from the fluid pressure actuator such that controlling the displacement of the first regenerating fluid pressure motor allows the flow rate of discharge fluid from the fluid pressure actuator as well as the pressure of the discharge flow path to be controlled; first energy regeneration device for regenerating the energy of discharge fluid as electrical energy, at least in part by rotating the first regenerating fluid pressure motor; the displacement of the first regenerating fluid pressure motor is controlled so that the flow rate of discharge fluid from the fluid pressure actuator varies from zero to a predetermined maximum value a relief flow path connected to a supply flow path for fluid to be supplied to the fluid pressure actuator between an intermediate part of the supply flow path and a fluid tank; a second displacement variable regenerating fluid pressure motor in the relief flow path such that controlling the displacement of the second regenerating fluid pressure motor allows the pressure of the supply flow path to the fluid pressure actuator to be controlled; and a second regeneration device for regenerating the rotational energy of fluid in the relief flow path as electrical energy, at least in part by rotating the second regenerating fluid pressure motor.