Loading patent…
AssigneeHitachi Construction Machinery Co., Ltd.
InventorsTsuyoshi Nakamura, Genroku Sugiyama, Tsukasa Toyooka, Kouji Ishikawa
Estimating the term…
A joining directional control valve 13 is disposed to supply, to an arm cylinder 4, not only a hydraulic fluid delivered from a first hydraulic pump 1, but also a hydraulic fluid delivered from a second hydraulic pump 2 when an arm directional control valve 14 is driven. Respective delivery pressures of the hydraulic pumps 1, 2 are detected by pressure sensors 101, 102, and the opening area of a recovery control valve 6 is controlled depending on a lower one of the detected pressures from the pressure sensors 101, 102 such that, even in the combined operation of the arm cylinder 4 and another actuator 3, 4, the hydraulic fluid can be recovered for return to the arm cylinder 4 when the load pressure of the arm cylinder 4 is low. Thus, by supplying the hydraulic fluids from the two hydraulic pumps to the particular actuator for which the hydraulic fluid is to be recovered, a recovery flow rate is ensured when the load of the particular actuator is low in the combined operation.
A hydraulic circuit for a working machine comprising a first hydraulic pump (1) for supplying a hydraulic fluid to a plurality of actuators (4, 5) including a particular actuator (4), a plurality of directional control valves (14, 15) including a particular directional control valve (14), which are connected in parallel with respect to said first hydraulic pump and control respective flows of the hydraulic fluid supplied to said plurality of actuators, a second hydraulic pump (2) for supplying a hydraulic fluid to another actuator (3) separate from said plurality of actuators, another directional control valve (11) for controlling a flow of the hydraulic fluid supplied from said second hydraulic pump, and a hydraulic recovery system comprising throttle means (6) disposed in a line (34) connecting a reservoir port (31) of said particular directional control valve and a reservoir (9), and a check valve (7) disposed in a line connecting a reservoir-side line (35) and a pump-side line (10C) of said particular directional control valve and allowing the hydraulic fluid to flow from the reservoir-side line to the pump-side line when the pressure in the reservoir-side line is higher than the pressure in the pump-side line,
A hydraulic circuit for a working machine comprising a first hydraulic pump (1) for supplying a hydraulic fluid to a plurality of actuators (4, 5) including a particular actuator (4), a plurality of directional control valves (14, 15) including a particular directional control valve (14), which are connected in parallel with respect to said first hydraulic pump and control respective flows of the hydraulic fluid supplied to said plurality of actuators, a second hydraulic pump (2) for supplying a hydraulic fluid to another actuator (3) separate from said plurality of actuators, another directional control valve (11) for controlling a flow of the hydraulic fluid supplied from said second hydraulic pump, and a hydraulic recovery system comprising throttle means (6) disposed in a line (34) connecting a reservoir port (31) of said particular directional control valve and a reservoir (9), and a check valve (7) disposed in a line connecting a reservoir-side line (35) and a pump-side line (10C) of said particular directional control valve and allowing the hydraulic fluid to flow from the reservoir-side line to the pump-side line when pressure in the reservoir-side line is higher than pressure in the pump-side line,
Dependencies are inferred from the claim text.