Patent ID: 8726664

Claim:
An engine lug-down suppressing device for hydraulic work machinery, provided on the hydraulic work machinery including: an engine; a variable displacement hydraulic pump that is driven by the engine; a hydraulic actuator that is driven by discharge oil of the variable displacement hydraulic pump; an operation instruction circuit for giving an instruction to cause the hydraulic actuator to operate; and a target engine rotational speed instruction input unit for giving an instruction on a target engine rotational speed of the engine, the engine lug-down suppressing device comprising: a detection controller for detecting the presence or absence of an instruction by the operation instruction circuit; and a pump absorption torque controller for controlling pump absorption torque of the variable displacement hydraulic pump in accordance with a detection result by the detection controller, wherein the pump absorption torque controller is operatively configured to serve as a: first controller for controlling pump absorption torque in accordance with the target engine rotational speed when no instruction is detected by the detection controller; and a second controller for controlling pump absorption torque in accordance with the target engine rotational speed when an instruction is detected by the detection controller, and wherein the pump absorption torque determined by the first controller falls within a range equal to or smaller than the pump absorption torque determined by the second controller in an entire range of the target engine rotational speed, and is set to approach the pump absorption torque determined by the second controller with an increase in the target engine rotational speed.