US 11,866,911 B2
Work vehicle and control method for fan of work vehicle
Yuji Fukuda, Sakai (JP); Hiroaki Nakagawa, Sakai (JP); Ryota Hamamoto, Sakai (JP); Yasuhiro Nishida, Sakai (JP); and Daiki Abe, Sakai (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by Kubota Corporation, Osaka (JP)
Filed on Sep. 16, 2022, as Appl. No. 17/946,047.
Claims priority of application No. 2021-210906 (JP), filed on Dec. 24, 2021.
Prior Publication US 2023/0203789 A1, Jun. 29, 2023
Int. Cl. E02F 9/22 (2006.01); F01P 7/04 (2006.01)
CPC E02F 9/226 (2013.01) [F01P 7/044 (2013.01); E02F 9/2296 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A control method for a fan of a work vehicle, comprising:
supplying, when an engine is started, a first current that has a first magnitude to a solenoid of a variable relief valve connected to an oil passage such that hydraulic fluid output from a hydraulic pump driven by the engine flows through the oil passage by a first flow rate to rotate a hydraulic motor connected to the oil passage;
supplying, 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 to the solenoid such that the hydraulic fluid flows through the oil passage by a second flow rate smaller than the first flow rate to reduce a rotational speed of the fan;
supplying, 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 a temperature of liquid flowing in the work vehicle;
supplying, from the start of the engine till when the rotational speed of the engine exceeds a third rotational speed threshold equal to or greater than the first rotational speed threshold value, a third current that has a third magnitude to an additional solenoid of an unload valve provided in parallel with the variable relief valve in an additional oil passage connected in parallel with the oil passage to shut off the additional oil passage by the unload valve;
supplying, when the rotational speed of the engine exceeds the third rotational speed threshold value, a fourth current that has a fourth magnitude larger than the third magnitude to the additional solenoid to open the unload valve such that the hydraulic fluid flows from the hydraulic pump into the additional oil passage; and
supplying, when the rotational speed of the engine is equal to or greater than the third rotational speed threshold and exceeds a fourth rotational speed threshold value equal to or less than the second rotational speed threshold value, a current corresponding to the temperature of the liquid through the additional solenoid to change a flow rate of the hydraulic fluid flowing through the additional oil passage.