US 12,312,772 B2
Hydraulic system for working machine
Yuji Fukuda, Sakai (JP); and Toshihiko Takemura, Sakai (JP)
Assigned to KUBOTA CORPORATION, Osaka (JP)
Filed by KUBOTA CORPORATION, Osaka (JP)
Filed on Nov. 1, 2023, as Appl. No. 18/385,962.
Application 18/385,962 is a continuation of application No. 17/841,716, filed on Jun. 16, 2022, granted, now 11,840,825.
Claims priority of application No. 2021-131401 (JP), filed on Aug. 11, 2021.
Prior Publication US 2024/0060271 A1, Feb. 22, 2024
Int. Cl. E02F 9/22 (2006.01)
CPC E02F 9/2253 (2013.01) [E02F 9/2235 (2013.01); E02F 9/2246 (2013.01); E02F 9/2296 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A hydraulic system for a working machine, the hydraulic system comprising:
a prime mover;
at least one traveling device including at least one of a plurality of crawlers or a plurality of wheels to cause the working machine to travel;
at least one traveling motor to transmit power to the at least one traveling device;
at least one variable displacement traveling pump to be driven by power from the prime mover to supply hydraulic fluid to the at least one traveling motor;
a plurality of first operators including at least two of a dial having a rotatable knob, a pedal, a lever, or a joystick to be operated by a user to drive the at least one traveling device;
a second operator including a switch to be operated by the user to perform switching to one of a first mode in which the working machine is caused to travel or a second mode in which the working machine is caused to travel at a travel speed lower than in the first mode;
a controller configured or programmed to control at least one of the prime mover or the at least one variable displacement traveling pump in accordance with an operation amount of the plurality of first operators and/or an operating state of the second operator; and
an adjuster including a solenoid valve fluidly connected to at least one pressure receiver of the at least one variable displacement traveling pump to adjust an angle of at least one swash plate of the at least one variable displacement traveling pump by hydraulically moving the at least one swash plate; wherein
the plurality of first operators include:
an accelerator including at least one of the dial having the rotatable knob or the pedal to be operated by the user to input a target rotational speed of the prime mover in the first mode; and
a travel operator including at least one of the lever or the joystick to be operated by the user to adjust a rotational speed of the at least one traveling motor in the first mode and in the second mode; and
the controller is configured or programmed to:
in the first mode, set the target rotational speed in accordance with an operation amount of the accelerator and control driving of the prime mover based on the set target rotational speed such that a rotational speed of the prime mover matches the target rotational speed; and
in the second mode, (i) cause the adjuster to change the angle of the at least one swash plate of the at least one variable displacement traveling pump in accordance with an operation amount the of the travel operator to adjust the rotational speed of the at least one traveling motor and the travel speed of the working machine, and (ii) in response to an operation of the accelerator when the operation amount of the travel operator is constant, cause the adjuster to change the angle of the at least one swash plate of the at least one variable displacement traveling pump without changing the rotational speed of the prime mover in accordance with the operation amount of the accelerator to adjust the rotational speed of the at least one traveling motor and the travel speed of the working machine.