Hydraulic type energy recovery system for potential energy of boom of excavator

A hydraulic type energy recovery system for potential energy of a boom of an excavator comprises a variable motor, two variable pumps, an energy accumulator, a control valve, an ECU, a pressure sensor, a revolution speed transducer, a hydraulic cylinder, an oil tank and an engine. Aiming at solving the problems that a great deal of potential energy of a boom of an existing hydraulic excavator under the working condition of severe change is wasted, a hydraulic type energy recovery system is arranged in parallel on the basis of not changing a hydraulic system and the operation performance of the existing excavator; the hydraulic type energy recovery system can recover the potential energy generated when the boom is released downwards, achieve flow regeneration of the boom in order to reduce oil consumption of the hydraulic excavator, and achieve the purpose of saving energy and reducing consumption.