US 11,718,977 B2
Work machine
Kento Kumagai, Ami-machi (JP); Shinya Imura, Toride (JP); Yasutaka Tsuruga, Ryugasaki (JP); Takaaki Chiba, Kasumigaura (JP); Hiroaki Amano, Tsukuba (JP); Shinji Nishikawa, Kasumigaura (JP); Akihiro Narazaki, Tsukuba (JP); and Genroku Sugiyama, Tsuchiura (JP)
Assigned to Hitachi Construction Machinery Co., Ltd., Tokyo (JP)
Appl. No. 17/640,947
Filed by Hitachi Construction Machinery Co., Ltd., Tokyo (JP)
PCT Filed Nov. 2, 2020, PCT No. PCT/JP2020/041098
§ 371(c)(1), (2) Date Mar. 7, 2022,
PCT Pub. No. WO2021/192389, PCT Pub. Date Sep. 30, 2021.
Claims priority of application No. JP2020-058818 (JP), filed on Mar. 27, 2020.
Prior Publication US 2022/0333352 A1, Oct. 20, 2022
Int. Cl. E02F 9/22 (2006.01); E02F 9/20 (2006.01)
CPC E02F 9/2292 (2013.01) [E02F 9/2004 (2013.01); E02F 9/2228 (2013.01); E02F 9/2296 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A work machine comprising:
a machine body;
a work device attached to the machine body;
a plurality of actuators that drive the machine body or the work device;
a hydraulic fluid tank;
a hydraulic pump that sucks hydraulic fluid from the hydraulic fluid tank and that supplies the hydraulic fluid to the plurality of actuators;
a plurality of flow rate controllers that are connected in parallel to a delivery line of the hydraulic pump and that control flow rates of the hydraulic fluid supplied from the hydraulic pump to the plurality of actuators;
control levers for giving instructions for operation of the plurality of actuators;
a pilot pump;
a plurality of solenoid proportional valves that reduce pressure of hydraulic fluid supplied from the pilot pump and that generate operation pressures of the plurality of flow rate controllers;
a controller that outputs command signals to the plurality of solenoid proportional valves according to operation amounts of the control levers; and
an automatic control function selector switch for giving an instruction to enable or disable an automatic control function for the machine body or the work device,
the controller being configured to, in a case where the automatic control function selector switch gives an instruction to enable the automatic control function, perform the automatic control function by correcting the command signals to the plurality of solenoid proportional valves, wherein
the work machine includes a bleed-off valve that is disposed on a hydraulic fluid line connecting the delivery line to the hydraulic fluid tank and adjusts a flow rate of the hydraulic fluid returned from the delivery line to the hydraulic fluid tank, and
the controller is configured to,
in a case where the automatic control function selector switch gives an instruction to disable the automatic control function, adjust an opening amount of the bleed-off valve to a maximum opening amount or an opening amount corresponding to input amounts of the control levers, and
in a case where the automatic control function selector switch gives the instruction to enable the automatic control function, adjust the opening amount of the bleed-off valve, in at least part of an operation region of the control levers, so as to be smaller than the opening amount with the instruction to disable the automatic control function being given.