DEVICE AND METHOD OF CONTROLLING HYDRAULIC DRIVE OF CONSTRUCTION MACHINERY

摘要

Control is performed so as to keep constant the operating speed of a work machine even when the work machine is operated in whatever way in construction machinery. Different engine output control lines T0-T3 and different pump torque lines M1-M4 corresponding to different operating types are defined. Any respective matching points between the engine output control lines T0-T3 and the pump torque lines M1-M4 designate a constant engine rotation speed N1. One engine output control line and one pump torque line are selected according to an operating type currently in effect. An engine output horsepower is controlled on an equivalent horsepower line equivalent to a horsepower obtained by adding a horsepower required by an auxiliary machines such as a cooling fan to a horsepower at a matching point between the selected both lines. The absorption torque of a work machine-use hydraulic pump is controlled on the selected pump torque line. The engine operates at a constant rotation speed N1 despite a variation in operating type or a variation in horsepower required by an auxiliary machine.