| 摘要 |
PROBLEM TO BE SOLVED: To smoothly perform operation of a cylinder 1, when a power generation mechanism G is fully charged, or even when any failure is caused. SOLUTION: In a power generation state, a first control valve 2 is kept in a second switching position C1, and a hydraulic fluid of a pressure loss quantity of an orifice 5 is supplied to the power generation mechanism G. In this state, an unillustrated controller keeps a pilot pressure control solenoid proportional valve 29 in an illustrated position, and keeps a second control valve 26 in an orifice function exhibiting position A2. When the power generation mechanism G is put in a fully charged state or a failure state, an unillustrated sensor senses it state, and transmits the state to the controller. At this time, the controller controls the pilot pressure control solenoid proportional valve 29; communicates pilot chambers 7 and 27 of the first and second control valves 2 and 26; switches the second control valve 26 to an orifice function releasing position C2; and returns the substantially whole quantity of return oil of a cylinder 1 to a tank T via the second control valve 26. COPYRIGHT: (C)2007,JPO&INPIT |
