| 摘要 |
PROBLEM TO BE SOLVED: To effectively utilize engine power without lowering the suction power of a hydraulic pump regardless of an increase in the temperature of hydraulic oil in a hydraulically controlled device to control the capacity of the hydraulic pump by taking those output pressures into account so that the input torque of the hydraulic pump may not exceed the limit value of the input torque, which the output pressures are the discharge pressure of the hydraulic pump and the output pressure of a solenoid proportional control valve and are individually introduced to the two pressure receiving chambers of a control valve for controlling the limit of input torque. SOLUTION: In the case where the temperature of hydraulic oil have increased from t1 to t2 near the mean temperature during the operation of an engine with a target engine speed set to the rated engine speed, for example, correction pressure Pb2, higher than correction pressure Pb1, is calculated by the calculation section 62 of a controller 50. The target output pressure Pc of a pressure reducing valve =Pa-Pb2, lower than the value having been set is calculated by a subtraction section 63. Then drive current I smaller than the current having been corresponded thereto is calculated by a drive current calculation section 64. The result is output to the solenoid proportional valve 30.
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