US 12,247,374 B2
Working machine
Ryota Hamamoto, Osaka (JP); Kazuki Ueda, Osaka (JP); and Daiki Abe, Osaka (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by KUBOTA CORPORATION, Osaka (JP)
Filed on Dec. 6, 2022, as Appl. No. 18/075,917.
Claims priority of application No. 2021-213681 (JP), filed on Dec. 28, 2021.
Prior Publication US 2023/0228062 A1, Jul. 20, 2023
Int. Cl. E02F 9/22 (2006.01); E02F 9/20 (2006.01)
CPC E02F 9/2228 (2013.01) [E02F 9/2004 (2013.01); E02F 9/2246 (2013.01); E02F 9/2253 (2013.01); E02F 9/2267 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A working machine, comprising:
a prime mover;
a traveling pump to operate by power of the prime mover and deliver a hydraulic fluid;
a traveling motor to rotate using the hydraulic fluid delivered by the traveling pump;
a machine body in which the prime mover, the traveling pump, and the traveling motor are provided;
a traveling switching valve operable to switch between a first state allowing a rotation speed of the traveling motor to increase up to a first maximum speed, and a second state allowing the rotation speed of the traveling motor to increase up to a second maximum speed higher than the first maximum speed;
a traveling manipulator including an operation valve to change hydraulic fluid pressure acting on the traveling pump in response to operation of an operation member; and
a controller configured or programmed to perform shift shock reduction control of reducing an amount of hydraulic fluid supply from the traveling pump to the traveling motor when shift-down switching from the second state to the first state is performed, the controller including
a first processor configured or programmed to, based on a drop amount that is a difference between a target number of revolutions of the prime mover and an actual number of revolutions of the prime mover, compute a first reduction amount for reducing the amount of hydraulic fluid supply from the traveling pump to the traveling motor in the shift shock reduction control;
a second processor configured or programmed to, based on a degree of straight traveling of the machine body, compute a second reduction amount for reducing the amount of hydraulic fluid supply from the traveling pump to the traveling motor in the shift shock reduction control; and
a reduction controller configured or programmed to, based on a reduction amount that is either the first reduction amount computed by the first processor or the second reduction amount computed by the second processor, whichever is larger in absolute value, perform the shift shock reduction control.