Swing drive controlling system for construction machine

摘要

The system includes: a variable displacement hydraulic pump supplying pressure oil to a hydraulic actuator; a pressure detector detecting a pump discharge pressure from the hydraulic pump; a control valve controlling a supply of the pressure oil to the hydraulic actuator; a controller controlling a pump displacement of the hydraulic pump; a hydraulic motor rotating an upper structure of the construction machine; a swing relief valve defining a relief pressure of the hydraulic motor; and a control lever switching a control valve for the hydraulic motor. The controller includes: an adjuster that, when a pump discharge pressure detected by the pressure detector exceeds a first set value, conducts an adjustment to reduce the pump displacement; and a canceller that cancels the adjustment when the pump discharge pressure falls below a second set value. The second set value is equal to or larger than the first set value.

主权项

1. A swing drive controlling system of a construction machine, comprising:
a variable displacement hydraulic pump that is driven by an engine, the variable displacement hydraulic pump supplying a pressure oil to a hydraulic actuator; a pressure sensor that detects a pump discharge pressure from the variable displacement hydraulic pump; a control valve that controls a supply of the pressure oil discharged by the hydraulic pump to the hydraulic actuator; a controller that controls a pump displacement of the variable displacement hydraulic pump; a hydraulic motor provided by a part of the hydraulic actuator, the hydraulic motor rotating an upper structure of the construction machine; a swing relief valve that defines a relief pressure of the hydraulic motor; and a control lever that switches a first control valve for the hydraulic motor that is provided by a part of the control valve, wherein the controller determines, while the control lever is operated, whether or not an adjustment of a pump absorption torque defined by a product of the pump displacement and the pump discharge pressure is to be conducted and whether or not the adjustment of the pump absorption torque of the variable displacement hydraulic pump is to be cancelled, based on the pump discharge pressure detected by the pressure sensor, and wherein the controller comprises:
an adjuster that, when the controller determines that the pump discharge pressure detected by the pressure sensor exceeds a first set value, conducts the adjustment to reduce the pump displacement in accordance with the pump discharge pressure and to adjust the pump absorption torque to be set at a value less than a predetermined value; anda canceller that cancels the adjustment by the adjuster when the controller determines that the pump discharge pressure detected by the pressure sensor falls below a second set value that is larger than the first set value.