Hydraulic drive system and method using a fuel injection control unit

摘要

A fuel injection control unit, including an electronic governor and a controller for an engine performs control in a governor region based on an isochronous characteristic. A working machine controller receives a delivery pressure signal P and controls a regulator such that, when the delivery pressure of a hydraulic pump exceeds a predetermined pressure P 1, the displacement of the hydraulic pump does not exceed a value decided in accordance with a preset pump absorption torque curve. The working machine controller controls the regulator such that, when the delivery pressure of the hydraulic pump 2 is not higher than the predetermined pressure P 1, the displacement of the hydraulic pump is increased as the delivery pressure of the hydraulic pump lowers from the predetermined pressure P 1.