| 摘要 |
PROBLEM TO BE SOLVED: To provide an excellent fine controllability when an engine speed is set at low level by improving a saturation phenomenon according to the engine speed in a load sensing control type hydraulic drive device. SOLUTION: Pressure differences across flow control valves 6a, 6b, and 6c are controlled to the same pressure differentialΔPLS by pressure compensating valves 7a, 7b, and 7c, respectively, and the pressure differentialΔPLS is maintained at a target pressure differentialΔPLSref by a pump capacity control device 5. Also, a flow detection valve 31 is installed to the delivery routes 30a and 30b for a fixed displacement hydraulic pump 30 so as to change the target pressure differentialΔPLSref according to a variation in the speed of an engine 1, and a pressure differentialΔPp across the variable throttling 31a of the flow detection valve 31 is led into a set change device 32 so as to change the target pressure differentialΔPLSref. Thus the flow detection valve 31 varies the opening area of the variable throttling 31a according to the pressure differentialΔPp across the variable throttling 31a itself, and also varies the pressure differentialΔPp according to the speed of the engine 1.
|
