US 12,221,769 B2
Work machine
Takaaki Chiba, Tsuchiura (JP); Kento Kumagai, Tsuchiura (JP); and Yusuke Imai, Tsuchiura (JP)
Assigned to Hitachi Construction Machinery Co., Ltd., Tokyo (JP)
Appl. No. 17/436,174
Filed by Hitachi Construction Machinery Co., Ltd., Tokyo (JP)
PCT Filed Aug. 7, 2020, PCT No. PCT/JP2020/030335
§ 371(c)(1), (2) Date Sep. 3, 2021,
PCT Pub. No. WO2021/059775, PCT Pub. Date Apr. 1, 2021.
Claims priority of application No. 2019-174623 (JP), filed on Sep. 25, 2019.
Prior Publication US 2022/0127823 A1, Apr. 28, 2022
Int. Cl. E02F 9/22 (2006.01); F15B 11/08 (2006.01); F15B 11/16 (2006.01)
CPC E02F 9/2285 (2013.01) [E02F 9/2228 (2013.01); E02F 9/2235 (2013.01); E02F 9/2267 (2013.01); E02F 9/2296 (2013.01); F15B 11/08 (2013.01); F15B 11/166 (2013.01); F15B 2211/20553 (2013.01); F15B 2211/355 (2013.01); F15B 2211/523 (2013.01); F15B 2211/575 (2013.01); F15B 2211/6346 (2013.01); F15B 2211/635 (2013.01); F15B 2211/67 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A work machine comprising:
a prime mover;
at least one main hydraulic pump driven by the prime mover;
a plurality of hydraulic actuators driven with pressure oil discharged from the main hydraulic pump;
a plurality of flow rate control valves adapted to control a flow rate of pressure oil to be supplied from the main hydraulic pump to the respective hydraulic actuators;
a pilot hydraulic pump adapted to supply pressure oil for driving the flow rate control valves; and
a controller configured to control a discharge flow rate of the pilot hydraulic pump,
wherein:
the controller is configured to control the discharge flow rate of the pilot hydraulic pump such that requested pilot flow rates determined in accordance with control commands for the respective flow rate control valves are subjected to a high-pass filtering process, thereby increasing the requested pilot flow rates only while the flow rate control valves start to move, and a preset standby flow rate is added to the requested pilot flow rates.