| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic device protected against burning and welding even if excessive current greater than assumption flows. SOLUTION: In the hydraulic device provided with a hydraulic pump 12, a DC motor 1 driving the hydraulic pump 12, and a tank storing working oil supplied to the hydraulic pump 12, electric potential of an input side A and an output side B of a contactor 14 put between the DC motor 11 and a battery 13 and supplying electric power to the DC motor 11 are measured. Current value flowing through the contactor 14 is calculated based on the electric potential difference. Allowable continuous operation time of the contactor 14 and the DC motor 11 is calculated by an operation device 16 based on the calculated current value and allowable continuous contact capacity of the contactor 14 or allowable continuous contact capacity of the DC motor 11. When continuous operation time exceeds the calculated allowable continuous operation time, contact of the contactor 14 is shut out by a contactor control part 15. COPYRIGHT: (C)2007,JPO&INPIT
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