| 摘要 |
PURPOSE:To carry out the capacity control for a hydranlic pump even in case of anomaly by obtaining an operation instruction value directly from the aimed value of a displacement volume through a control passage for obtaining a fundamental instruction value and open-loop-controlling the pump, when a detecting means for detecting the displacement volume of the hydraulic pump detects anomaly. CONSTITUTION:A pressure difference meter 7 for detecting the differential pressure P between the discharge pressure Pa of a hydraulic pump and the load pressure of a hydraulic motor, a pressure detector 8 for detecting the discharge pressure Ps, and a displacement detector 9 for detecting the swash plate position (displacement volume) of the hydraulic pump are provided. The aimed position thetao of the swash plate is calculated from the differential pressure P and the discharge pressure Pa by a block 30 in a controller, and an instruction signal X is generated from thetao in a block 31. In this case, the fundamental instruction value io is obtained from the aimed position thetao in the block 31, and the correction value ic is obtained from the difference between thetao and a detection position. When the displacement detector 9 gives an anomaly judgement 44, a switch 40 is turned OFF, and the operation instruction value X is obtained directly from the fundamental instruction value io. |
