Patent ID: 11866911
Assignee: KUBOTA CORPORATION
Field: Civil engineering (Other fields)
Classification: CPC E  F | IPC E  F

Claim 9:
10. A work vehicle comprising:
an engine;
a hydraulic pump to be driven by the engine to supply hydraulic fluid;
an oil passage connected to the hydraulic pump through which the hydraulic fluid flows;
a hydraulic motor provided in the oil passage to be rotated by the hydraulic fluid; and
a fan connected to the hydraulic motor to rotate together with the hydraulic motor;
a variable relief valve connected to the oil passage and having a solenoid, the variable relief valve being configured to control a flow rate of the hydraulic fluid flowing through the oil passage in accordance with a current flowing through the solenoid; and
circuitry configured to control the magnitude of the current flowing through the solenoid to control a rotational speed of the fan,
the circuitry being configured to supply, when the engine is started, a first current that has a first magnitude to the solenoid such that the hydraulic fluid flows through the oil passage by a first flow rate to rotate the fan connected to the oil passage,
the circuitry being configured to supply, when a rotational speed of the engine becomes larger than a first rotational speed threshold value, a second current that has a second magnitude larger than the first magnitude such that the hydraulic fluid flows through the oil passage by a second flow rate smaller than the first flow rate to reduce the rotational speed of the fan, and
the circuitry being configured to supply, when the rotational speed of the engine becomes larger than a second rotational speed threshold value that is larger than the first rotational speed threshold value, a current to the solenoid to change the rotational speed of the fan, the current corresponding to the temperature of the liquid flowing in the work vehicle,
wherein, when the rotational speed of the engine exceeds the first rotational speed threshold value, the circuitry is configured to supply the second current to the solenoid until the rotational speed falls below the fifth rotational speed threshold value.