CONTROL DEVICE OF WORK MACHINE

PROBLEM TO BE SOLVED: To provide a control device of a work machine capable of improving an responsiveness of an actuator, cost, an occurrence of noise, and easiness of control. SOLUTION: The rotating shaft of a variable displacement pump/motor 6 of a constant direction rotating system is connected to the rotating shaft of an electric motor/generator 4. The discharge port 6d and the intake port 6s of the variable displacement pump/motor 6 are connected to two ports of a hydraulic cylinder F through a closed circuit 7. A control valve 8 for directional control and flow control connected to form a bridge circuit by combining four solenoid proportional flow control valves 8a, 8b, 8c, and 8d with each other is installed in the closed circuit 7. A passage 7c connected to the head chamber Fh of the hydraulic cylinder F and a passage 7d connected to a rod chamber Fr are communicably connected to a passage between a check valve 12 on the suction side and a tank 13 through external pilot system relief valves 9 and 10. COPYRIGHT: (C)2007,JPO&INPIT