Kubota Corporation

Kazuki Ueda

Ryota Hamamoto

Yuji Fukuda

Daiki Abe

Kohei Nagao

Yuya Konishi

Kohei Kurachi

Hiroaki Nakagawa

Jun Tomita

Keisuke Naito

Masaki Inaoka

Yuya Tanabe

Yudai Koga

Yasushi Otagaki

In a working machine, a controller decreases a supply amount of hydraulic fluid from a travel pump to a travel motor based on a travel state of a machine body when a speed-change instruction is issued by operating a switch. When a speed-increase operation is performed, the controller switches the travel switching valve from the first state to the second state in a prior period lasting up to when the supply amount to the travel motor starts decreasing, in a restoration period in which the supply amount to the travel motor after being decreased is being restored, or in an after-restoration period in which the supply amount has been restored.

Working machine

A working machine includes a controller that performs shift shock reduction control when shift-down switching from a second state to a first state, in which a motor speed can be increased up to a first maximum speed lower than a second maximum speed available in the second state, is performed. The controller includes a first processor configured to, based on a drop amount that is a difference between target and actual numbers of revolutions of a prime mover, compute a first reduction amount for reducing an amount of hydraulic fluid supply from a traveling pump to a traveling motor, a second processor configured to compute a second reduction amount based on a degree of straight traveling of a machine body, and a reduction controller configured to, based on the first or second reduction amount, whichever is larger in absolute value, perform the shift shock reduction control.

A working machine includes first and second traveling pumps, an acquirer to acquire the number of revolutions and the rotation direction of each of first and second traveling motors, a determiner to, based on the acquired number of revolutions and the acquired rotation direction, determine whether a machine body is in a straight traveling state or a turn traveling state, and a controller configured or programmed to, when switching from a first state allowing rotation speeds of the first and second traveling motors to increase up to a first maximum speed, to a second state allowing the rotation speeds to increase up to a second maximum speed higher than the first maximum speed, or vice versa, is performed, reduce an amount of hydraulic fluid supply from the pumps to the motors according to the straight traveling state or the turn traveling state of the machine body.

A working machine includes a prime mover, a traveling pump configured to deliver hydraulic fluid at a flow rate corresponding to an angle of the swashplate, a traveling motor configured to be rotated by the hydraulic fluid delivered from the traveling pump so as to have a rotation speed shiftable between a first speed and a second speed higher than the first speed, a traveling change-over valve shiftable between a first state to set the rotation speed of the traveling motor to the first speed and a second state to set the rotation speed of the traveling motor to the second speed, an operation device, an operation valve configured to change the angle of the swashplate of the traveling pump according to operation of the operation device, an actuation valve provided upstream or downstream of the operation valve and fluidly connected to the operation valve, and a controller configured or programmed to output a control signal to control the actuation valve in such a way that, when the traveling change-over valve is shifted from the second state to the first state, a value of the control signal is reduced from a set value to a mitigation value less than the set value and then restores to the set value. The controller is configured or programmed to reduce the value of the control signal from the set value to the mitigation value for a mitigation period in such a way that a first reduction rate that is a rate of reducing the value of the control signal for a first part of the mitigation period between a start point thereof and an intermediate point thereof larger than a second reduction rate that is a rate of reducing the value of the control signal for a second part of the mitigation period between the intermediate point thereof and an end point thereof.

A working machine includes a prime mover, a traveling motor a speed shifting valve configured to shift an output speed of the traveling motor between a first speed and a second speed faster than the first speed, an actuation valve to change a hydraulic pressure applied to the speed shifting valve, a brake shiftable between a braking state to brake the traveling motor and a braking releasing state to release the braking, and a controller configured or programmed to control the actuation valve and the brake, and being capable of activate a warm-up mode. The controller, when activating the warm-up mode, shifts the brake into the braking state, and controls the actuation valve so as to make the hydraulic pressure applied to the speed shifting valve equal to or greater than a value corresponding to the second speed.

A working machine includes: a machine body provided thereon with a traveling pump and a traveling motor; a traveling change-over valve shiftable between a first state where a rotation speed of the traveling motor is set to a first speed and a second state where the rotation speed is set to a second speed; an actuation valve operable to control a flow of operation fluid to an operation valve that changes a pressure of operation fluid to be applied to the traveling pump according to operation of an operation member; and a controller to perform a shock-mitigation control for reducing an opening degree of the actuation valve when the traveling change-over valve is shifted from the first state to the second state. The controller determines a reduction amount of the opening degree of the actuation valve reduced by the shock-mitigation control, based on a straight-traveling degree of the machine body.

In a working machine, a traveling pump is driven by a prime mover to rotate a traveling motor by fluid therefrom. The traveling motor has a rotation speed shiftable between a lower first speed and a higher second speed. A traveling change-over valve is shiftable between a first state where the rotation speed of the traveling motor is set to the first speed and a second state where the rotation speed of the traveling motor is set to the second speed. A controller performs a shock-mitigation for reducing a rotation speed of the prime mover when the traveling change-over valve is shifted from the second state to the first state. The controller determines a reduction amount of rotation speed of the prime mover reduced by the shock mitigation based on a difference between a target rotation speed of the prime mover and an actual rotation speed of the prime mover.

A working machine includes a fan motor driven with hydraulic fluid, the fan motor including a first port and a second port, a bypass fluid passage connecting the first port of the fan motor and the second port to each other, a flow rate control valve provided on the bypass fluid passage to control a flow rate of the hydraulic fluid flowing in the bypass fluid passage, a drain passage configured to drain the hydraulic fluid upstream of the flow rate control valve, and an unloading valve shiftable between a full-closing position to close the drain passage and a full-opening position to open the drain passage.

Growing community of inventors

Osaka, Japan

Kazuki Ueda