초록 ▼

A hydraulic control system according to the present invention for a construction machine is provided with a directional control valve switchable by a pilot control valve, a hydraulic cylinder, a pilot pump, a selector valve for selecting one of a maximum value out of pilot pressures of the pilot con

A hydraulic control system according to the present invention for a construction machine is provided with a directional control valve switchable by a pilot control valve, a hydraulic cylinder, a pilot pump, a selector valve for selecting one of a maximum value out of pilot pressures of the pilot control valve, a flow control unit for controlling the flow rate of a variable displacement hydraulic pump, a pressure-reducing valve for converting a delivery pressure of the pilot pump to a pump control signal, which controls driving of the flow control unit, in accordance with a pilot pressure guided to a first signal line connected to the selector valve, a branch line connecting the pilot pump and the pressure-reducing valve with each other, and a second signal line for guiding the pump control signal, which has been converted at the pressure-reducing valve, to the flow control unit.

대표청구항 ▼

[ What is claimed is:] [1.] A hydraulic control system for a construction machine provided with a variable displacement hydraulic pump, an actuator driven by pressure fluid delivered from said variable displacement hydraulic pump, a directional control valve for controlling a flow of said pressure f

[ What is claimed is:] [1.] A hydraulic control system for a construction machine provided with a variable displacement hydraulic pump, an actuator driven by pressure fluid delivered from said variable displacement hydraulic pump, a directional control valve for controlling a flow of said pressure fluid delivered from said variable displacement hydraulic pump and to be fed to said actuator, a pilot control valve capable of outputting plural pilot pressures for switching said directional control valve, a pilot pump for feeding pressure fluid to said pilot control valve, a selector valve for selecting one of a maximum value out of said plural pilot pressures outputted from said pilot control valve, and a flow control unit for controlling a delivery rate of said variable displacement hydraulic pump on a basis of said pilot pressure selected by said selector valve, wherein said hydraulic control system comprises:a first signal line for guiding said pilot pressure selected by said selector valve;a pressure control valve for converting a delivery pressure of said pilot pump to a pump control signal, which serves to control driving of said flow control unit, in accordance with said pilot pressure guided through said first signal line;a branch line for connecting said pilot pump and said pressure control valve with each other; anda second signal line for guiding said pump control signal, which has been converted by said pressure control valve, to said flow control unit.