US 12,435,492 B2
Hydraulic system of working machine and working machine
Hiroshi Horii, Osaka (JP); and Hiroya Mori, Osaka (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by KUBOTA CORPORATION, Osaka (JP)
Filed on Jun. 12, 2024, as Appl. No. 18/741,261.
Application 18/741,261 is a continuation of application No. PCT/JP2022/045018, filed on Dec. 7, 2022.
Claims priority of application No. 2022-000604 (JP), filed on Jan. 5, 2022.
Prior Publication US 2024/0328122 A1, Oct. 3, 2024
Int. Cl. E02F 9/22 (2006.01)
CPC E02F 9/2285 (2013.01) [E02F 9/2228 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A hydraulic system of a working machine, comprising:
a hydraulic actuator to be driven by a hydraulic fluid;
a direction switching valve to change a flow rate of the hydraulic fluid to be supplied to the hydraulic actuator to control an operation of the hydraulic actuator;
a solenoid proportional valve to control a switching position of the direction switching valve by a solenoid being energized in accordance with a supplied current;
a controller to control a current to be supplied to the solenoid proportional valve;
an operation member for a worker to operate the hydraulic actuator; and
a permission operation actuator capable of performing a switching operation between a permission operation for permitting driving of the hydraulic actuator and a non-permission operation for not permitting the driving, wherein
when the permission operation actuator is subjected to the non-permission operation and a temperature of the hydraulic fluid is lower than a predetermined temperature, the controller supplies, to the solenoid proportional valve, a first standby current of a first current value defined in a range in which the switching position of the direction switching valve is not switched;
wherein, when the permission operation actuator is subjected to the non-permission operation and the temperature of the hydraulic fluid is higher than or equal to the predetermined temperature, the controller does not supply a current to the solenoid proportional valve.