| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic circuit or a construction machine that can collect return oil and re-supply the collected return oil by one oil passage by using a hydraulic drive part capable of supplying pressure oil in two directions.SOLUTION: A hydraulic circuit includes: a pressure accumulator 21 which collects return oil of hydraulic actuators 11a, 14m; a hydraulic drive part 22 which is arranged in an oil passage between the hydraulic actuators and pressure accumulator; and a motor generator Mtr which is mechanically connected to an output shaft of the hydraulic drive part. When the pressure of the return oil is higher than pressure to be accumulated in the pressure accumulator during the collection of the return oil, the hydraulic drive part uses the motor generator as an electric generator, collects part of pressure energy of the return oil by the motor generator, reduces and accumulates the pressure of the return oil in the pressure accumulator. When the pressure of the return oil is lower than the pressure for accumulating the pressure in the pressure accumulator, on the other hand, the hydraulic drive part uses the motor generator as the electric generator, and adds driving energy of the motor generator as pressure energy to the return oil so as to increase and accumulate the pressure of the return oil in the pressure accumulator. |
