| 摘要 |
PROBLEM TO BE SOLVED: To hold hydraulic pressure of a hydraulic cylinder at a low cost while considering a hydraulic pressure drop in valve closing operation.SOLUTION: When supplying pressure oil from a hydraulic pump 11 to a hydraulic cylinder 12 via a hydraulic circuit 13 including a pilot check valve 15 to operate the hydraulic cylinder 12 and holding the hydraulic pressure, the hydraulic pump 11 is driven, the pilot check valve 15 is opened to increase hydraulic pressure of the hydraulic cylinder 12 to a predetermined magnitude Pa, and then the hydraulic pump 11 is stopped. After that, the hydraulic pump 11 is driven again and the pilot check valve 15 is kept in a half-opening state to increase the hydraulic pressure again.SELECTED DRAWING: Figure 1 |
