Patent attributes
A shovel includes a lower traveling body, an upper rotating body mounted on the lower traveling body, an internal-combustion engine including a supercharger and being controlled at a constant revolution speed, a hydraulic pump coupled to the internal-combustion engine, a hydraulic actuator to be driven by a hydraulic oil discharged from the hydraulic pump, a control valve system including multiple flow control valves for controlling a flow of the hydraulic oil discharged from the hydraulic pump, and a controller that controls an absorbing horsepower of the hydraulic pump. The controller is configured to increase a boost pressure of the supercharger before a load is applied to the hydraulic actuator by controlling a specific flow control valve in the control valve system to limit or block the flow of the hydraulic oil discharged from the hydraulic pump and thereby increasing a discharge pressure of the hydraulic pump.
