US 12,442,160 B2
Hydraulic system, excavator, and control method of excavator
Wataru Sumino, Tokyo (JP); Daisuke Kozuka, Tokyo (JP); Akira Hasebe, Tokyo (JP); and Masatoshi Ikeda, Tokyo (JP)
Assigned to KOMATSU LTD., Tokyo (JP)
Appl. No. 18/684,718
Filed by Komatsu Ltd., Tokyo (JP)
PCT Filed Aug. 10, 2022, PCT No. PCT/JP2022/030565
§ 371(c)(1), (2) Date Oct. 15, 2024,
PCT Pub. No. WO2023/053736, PCT Pub. Date Apr. 6, 2023.
Claims priority of application No. 2021-160635 (JP), filed on Sep. 30, 2021.
Prior Publication US 2025/0290287 A1, Sep. 18, 2025
Int. Cl. E02F 9/22 (2006.01); E02F 9/12 (2006.01); F15B 11/17 (2006.01); F15B 21/0427 (2019.01); F16K 49/00 (2006.01)
CPC E02F 9/2203 (2013.01) [E02F 9/123 (2013.01); E02F 9/2289 (2013.01); E02F 9/2292 (2013.01); F15B 11/17 (2013.01); F15B 21/0427 (2019.01); E02F 9/2296 (2013.01); F15B 2211/3116 (2013.01); F16K 49/005 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A hydraulic system comprising:
a main hydraulic valve that is constituted by an open circuit that includes a main pump, a working equipment cylinder, a main valve that controls inflow of hydraulic oil from the main pump to the working equipment cylinder, and a tank to which the hydraulic oil that has flowed out of the working equipment cylinder is ejected via the main valve;
a swing hydraulic circuit that is constituted by a closed circuit that includes a swing pump, a swing motor, and a neutral hold valve that controls passing of the hydraulic oil between the swing pump and the swing motor;
a back pressure valve that is disposed on a tank flow passage between the main valve and the tank, and adjusts back pressure of the main valve;
a warming-up flow passage that is disposed around a spool of the neutral hold valve;
a supply flow passage that connects an upstream portion of the tank flow passage between the main valve and the back pressure valve to an entrance port of the warming-up flow passage; and
an ejection flow passage that connects a downstream portion of the tank flow passage between the back pressure valve and the tank to an exit port of the warming-up flow passage.
 
8. A control method of an excavator that includes:
a main hydraulic circuit that is constituted by an open circuit that includes a main pump, a working equipment cylinder, a main valve that controls inflow of hydraulic oil from the main pump to the working equipment cylinder, and a tank to which the hydraulic oil that has flowed out of the working equipment cylinder is ejected via the main valve;
a swing hydraulic circuit that is constituted by a closed circuit that includes a swing pump, a swing motor, and a neutral hold valve that controls passing of the hydraulic oil between the swing pump and the swing motor; and
a back pressure valve that is disposed on a tank flow passage between the main valve and the tank, and adjusts back pressure of the main valve, the control method comprising:
causing the hydraulic oil to flow into a warming-up flow passage that is disposed around a spool of the neutral hold valve from an upstream portion of the tank flow passage between the main valve and the back pressure valve; and
causing the hydraulic oil to flow out of the warming-up flow passage to a downstream portion of the tank flow passage between the back pressure valve and the tank.