US 12,392,111 B2
Work machine
Taro Akita, Tsuchiura (JP); Shota Ishida, Tsukuba (JP); Mitsuhiko Kanehama, Kasumigaura (JP); and Ryohei Fukuchi, Tsukuba (JP)
Assigned to HITACHI CONSTRUCTION MACHINERY CO., LTD., Tokyo (JP)
Appl. No. 18/850,738
Filed by HITACHI CONSTRUCTION MACHINERY CO., LTD., Tokyo (JP)
PCT Filed Mar. 10, 2023, PCT No. PCT/JP2023/009308
§ 371(c)(1), (2) Date Sep. 25, 2024,
PCT Pub. No. WO2023/189421, PCT Pub. Date Oct. 5, 2023.
Claims priority of application No. 2022-058663 (JP), filed on Mar. 31, 2022.
Prior Publication US 2025/0223782 A1, Jul. 10, 2025
Int. Cl. E02F 9/22 (2006.01); E02F 9/20 (2006.01); F15B 11/042 (2006.01); F15B 11/044 (2006.01); F15B 11/08 (2006.01)
CPC E02F 9/2203 (2013.01) [E02F 9/2004 (2013.01); F15B 11/042 (2013.01); F15B 11/044 (2013.01); F15B 11/08 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A work machine comprising:
a prime mover;
a hydraulic pump configured to pump a hydraulic oil upon being driven by the prime mover;
a hydraulic actuator configured to operate upon being supplied with or discharging the hydraulic oil;
a supply flow path for supplying the hydraulic oil pumped by the hydraulic pump to the hydraulic actuator;
a return flow path for bringing the hydraulic oil discharged from the hydraulic actuator to a hydraulic oil tank;
a directional control valve having a spool that moves between a supply and discharge position and a blocking position, the supply and discharge position being a position for opening the supply flow path and the return flow path to cause the hydraulic oil to be supplied to and discharged from the hydraulic actuator, and the blocking position being a position for blocking the supply flow path and the return flow path to stop the hydraulic oil to be supplied to and discharged from the hydraulic actuator;
an operation device configured to be operated between an operation position corresponding to the supply and discharge position of the spool and a neutral position corresponding to the blocking position of the spool; and
a controller configured to bring the spool closer to the supply and discharge position as the operation device approaches the operation position to increase a volume of the hydraulic oil to be supplied to and discharged from the hydraulic actuator, and bring the spool closer to the blocking position as the operation device approaches the neutral position to reduce the volume of the hydraulic oil to be supplied to and discharged from the hydraulic actuator, wherein
in a case where the operation device has been operated from the operation position toward the neutral position, the controller is configured to:
move the spool from the supply and discharge position toward the blocking position at a first speed that is slower than a reference speed in a case where an operation speed of the operation device is less than a quick operation threshold; and
move the spool from the supply and discharge position toward the blocking position at a second speed that is faster than the first speed in a case where the operation speed is equal to or more than the quick operation threshold.