| CPC E02F 9/2228 (2013.01) [E02F 9/2267 (2013.01); E02F 9/2271 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01); F15B 13/044 (2013.01); E02F 9/2296 (2013.01); F15B 2211/35 (2013.01)] | 3 Claims |
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1. A work machine comprising:
a machine body;
a work device including a boom attached to the machine body, an arm attached to a distal end of the boom, and a bucket attached to a distal end of the arm;
a plurality of actuators that drive the machine body or the work device;
a hydraulic pump;
a plurality of directional control valves that are connected in parallel to a delivery line of the hydraulic pump and adjust flows of hydraulic fluid supplied from the hydraulic pump to the plurality of actuators;
a control lever for giving an instruction for operation of the plurality of actuators;
a pilot pump;
a solenoid valve unit plurality of solenoid proportional pressure reducing valves that reduces reduce a pressure of hydraulic fluid supplied from the pilot pump, and outputs output the reduced pressure as operation pressures of the plurality of directional control valves;
a controller that outputs commands to the solenoid valve unit plurality of solenoid proportional pressure reducing valves according to an operation instruction amount from the control lever; and
auxiliary flow rate controllers that are respectively arranged upstream of the plurality of directional control valves and limit flow rates of hydraulic fluid supplied from the hydraulic pump to the plurality of directional control valves; wherein
the auxiliary flow rate controllers each include
a seat type main valve, the main valve being provided with a control variable restrictor that changes an opening area according to an amount of movement of a valve body of the main valve,
a control variable restrictor that changes an opening area according to an amount of movement of a valve body of the main valve,
a pilot line that connects a downstream side of the main valve and a downstream side of the control variable restrictor to each other and decides the amount of movement of the valve body according to a passing flow rate, and
a spool type pilot variable restrictor that is disposed on the pilot line and changes an opening area according to a command from the controller;
the auxiliary flow rate controllers each being configured such that
an opening amount of the auxiliary flow rate controller is controlled by changing an opening area of the main valve changes between a maximum opening amount and zero according to the opening area of the pilot variable restrictor in a case where the opening area of the pilot variable restrictor is equal to or more than a predetermined opening area due to a large demanded flow rate of the actuator and
the opening amount of the auxiliary flow rate controller is controlled by making the opening area of the main valve is zero irrespective of and controlling only the opening area of the pilot variable restrictor in a case where the opening area of the pilot variable restrictor is less than the predetermined opening area due to a small demanded flow rate of the actuator.
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