HYDRAULIC CIRCUIT CONTROL DEVICE OF CONSTRUCTION MACHINERY

摘要

Whether a previously computed valve command value Y-1 is within a neutral zone +/- alpha is determined. If the determination result is "Yes", processing to compute a valve command value for a neutral dead zone is executed. If the determination result is "No", processing to compute a valve command value for a driving zone is executed. In the latter case, by using a valve command value X and the previously computed valve command value Y-1, it is determined in which one of acceleration, deceleration/stop, and lever-reversed condition is the operating status, and a maximum setting rate in one of acceleration, deceleration/stop, and lever-reversed condition is computed from a corresponding function DELTA Y = fmax1(X), etc. Then, a control signal is computed while restraining a change rate of the operational signal to be kept not more than the computed maximum change rate, and a flow control valve 3 is controlled in accordance with the computed control signal. As a result, in a hydraulic drive system for controlling a flow control valve with an electrical operational signal to control the operation of an actuator, the flow control valve can be controlled at an optimum maximum change rate in any operating status of acceleration, deceleration/stop, and lever-reversed condition.