US 12,312,771 B2
Work vehicle and control method for work vehicle
Kohei Nagao, Sakai (JP); Daiki Abe, Sakai (JP); and Ryota Hamamoto, Sakai (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by KUBOTA CORPORATION, Osaka (JP)
Filed on Aug. 1, 2023, as Appl. No. 18/362,961.
Claims priority of application No. 2022-127922 (JP), filed on Aug. 10, 2022.
Prior Publication US 2024/0052598 A1, Feb. 15, 2024
Int. Cl. E02F 9/22 (2006.01)
CPC E02F 9/2221 (2013.01) [E02F 9/2246 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01); E02F 9/2296 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A work vehicle comprising:
a hydraulic motor configured to drive a traveling device;
a hydraulic pump having a pilot port to which pilot pressure of pilot oil is applied, the hydraulic pump being configured to supply hydraulic fluid to the hydraulic motor in accordance with the pilot pressure;
an engine configured to drive the hydraulic pump;
a rotation speed sensor configured to detect a rotation speed of the engine;
a pilot pump configured to be driven by the engine to discharge the pilot oil;
an operation lever configured to receive an instruction of a travel direction from a user;
an operation valve configured to control the pilot pressure by operation of the operation lever;
a first pilot oil passage connecting the pilot pump and the operation valve, the pilot oil being supplied through the first pilot oil passage;
a primary pressure control valve provided in the first pilot oil passage and configured to control a pilot primary pressure which is a pressure of the pilot oil in the first pilot oil passage;
a second pilot oil passage connecting the operation valve and the pilot port, the pilot oil being supplied through the second pilot oil passage;
a secondary pressure control valve connected to the second pilot oil passage and configured to control a pilot secondary pressure which is a pressure of the pilot oil in the second pilot oil passage;
control circuitry configured to control the rotation speed of the engine according to a target rotation speed of the engine, and control the primary pressure control valve and the secondary pressure control valve based on a first target value of the pilot primary pressure and a second target value of the pilot secondary pressure; and
the control circuitry being configured to reduce the first target value and the second target value such that the second target value is higher than the first target value when the rotation speed of the engine detected by the rotation speed sensor becomes lower than the target rotation speed by a predetermined speed difference or more.