Kubota Corporation

Kohei Nagao

Yuji Fukuda

Ryota Hamamoto

Hiroaki Nakagawa

Daiki Abe

Kazuki Ueda

Ryuki Nishimoto

Tomoyuki Noguchi

Jun Tomita

Yoshimitsu Tanaka

Kohei Kurachi

Yudai Koga

Masahiro Toyama

A work vehicle includes a primary pressure control valve configured to control a pilot primary pressure of pilot oil. A secondary pressure control valve is configured to control a pilot secondary pressure of the pilot oil. Control circuitry is configured to control a rotation speed of an engine according to a target rotation speed. The control circuitry is configured to 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.

Work vehicle and control method for work vehicle

A working machine includes: at least one support member connectable to a work attachment to do work by making contact with an object to be contacted; at least one hydraulic cylinder to move the work attachment connected to the at least one support member, a rod-side pressure detector to detect a rod-side hydraulic pressure of hydraulic fluid in communication with a rod-side fluid chamber of the at least one hydraulic cylinder; a bottom-side pressure detector to detect a bottom-side hydraulic pressure of hydraulic fluid in communication with a bottom-side fluid chamber of the at least one hydraulic cylinder; and a controller to calculate a relationship in pressure between the rod-side hydraulic pressure and the bottom-side hydraulic pressure and evaluate, based on the calculated relationship in pressure, a contact state which is a state of contact of the work attachment with the object.

Working machine

A working machine includes a first pressure detector configured to detect a first pilot pressure that is a pressure of operation fluid passed through a first traveling fluid line, a second pressure detector configured to detect a second pilot pressure that is a pressure of operation fluid passed through a second traveling fluid line, a third pressure detector configured to detect a third pilot pressure that is a pressure of operation fluid passed through a third traveling fluid line, a fourth pressure detector configured to detect a fourth pilot pressure that is a pressure of operation fluid passed through a fourth traveling fluid line, and a controller configured or programed to judge in which of the left-front, right-front, left-rear and right-rear operation areas an operational position of the traveling operation member exists.

A work vehicle includes a primary pressure control valve configured to control a pilot primary pressure of pilot oil. A secondary pressure control valve is configured to control a pilot secondary pressure of the pilot oil. Control circuitry is configured to control a rotation speed of an engine according to a target rotation speed. The control circuitry is configured to 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. The control circuitry is 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 a rotation speed sensor becomes lower than the target rotation speed by a predetermined speed difference or more.

A working machine includes a first rotation detector to detect a first rotation speed of the left traveling motor, a second rotation detector to detect a second rotation speed of the right traveling motor, and a controller to perform automatic deceleration to automatically reduce the first rotation speed and the second rotation speed both set at respective second speed stages by shifting a speed stage of each of the first rotation speed and the second rotation speed to a first speed stage that is lower than the second speed stage. During straight traveling of a machine body of the working machine, the controller determines a straight-traveling threshold serving as a deceleration threshold for judging whether to perform the automatic deceleration based on the first rotation speed or the second rotation speed.

A hydraulic system for a working machine includes first and second hydraulic actuators actuated by hydraulic fluid delivered by a hydraulic pump, a first flow rate controller to control a first supply flow rate of hydraulic fluid supplied to the first hydraulic actuator to match a first required flow rate, a second flow rate controller to control a second supply flow rate of hydraulic fluid supplied to the second hydraulic actuator to match a second required flow rate, and a special flow rate control system to, if a sum of the first and second required flow rates is greater than a maximum delivery flow rate of the hydraulic pump, reduce the first supply flow rate to allow the second supply flow rate to approach the second required flow rate.

Hydraulic system for working machine

In a working machine, a controller is configured or programmed to control actuation of a blocking switching valve and a solenoid valve, to cause the blocking switching valve to unblock a first pilot fluid passage to perform switching to a first operation pattern in which an operation device operates a first device via a first control valve and a first hydraulic actuator, and cause the blocking switching valve to block a second pilot fluid passage and control the solenoid valve based on pilot pressure detected by a pressure detector to perform switching to a second operation pattern in which the operation device operates a second device via a second control valve and a second hydraulic actuator.

A working machine includes a controller to perform an automatic deceleration operation to automatically decelerate from a second speed to a first speed when a value calculated based on a first traveling pressure, a second traveling pressure, a third traveling pressure, and a fourth traveling pressure becomes equal to or more than a deceleration threshold in a state where a left traveling motor and a right traveling motor are being driven at the second speed. The controller determines the deceleration threshold based on any one of a first cross-differential pressure acquired by subtracting the fourth traveling pressure from the first traveling pressure, a second cross-differential pressure acquired by subtracting the third traveling pressure from the second traveling pressure, a third cross-differential pressure acquired by subtracting the second traveling pressure from the third traveling pressure, and a fourth cross-differential pressure acquired by subtracting the first traveling pressure from the fourth traveling pressure.

A working machine includes a traveling motor that is shifted between a first speed and a second speed faster than the first speed, a traveling pump that supplies hydraulic fluid to the traveling motor, a traveling operation member operable to operate the traveling pump, and a controller including an automatic speed reduction unit that performs automatic speed reduction in which the traveling motor having been shifted to the second speed is automatically shifted from the second speed to the first speed based on the operation amount of the traveling operation member. The controller includes an automatic speed reduction restraining unit configured or programmed to restrain the automatic speed reduction from being performed when the traveling operation member is operated to steeply change the operation amount from a first operation amount to a second operation amount.

A working machine includes a machine body, a traveling device provided on the machine body, an operation member operable to activate the traveling device, a camera device to capture an image of surroundings of the machine body, a display unit to display the image captured by the camera device, a notification unit to notify a traveling direction of the traveling device, and a controller to control the display unit and the notification unit so that when the operation member is operated to activate the traveling device, the display unit is controlled to display the captured image and the notification unit is controlled to notify the traveling direction. The controller delays either one of a first timing when the display unit starts to display the captured image and a second timing when the notification unit starts to notify the traveling direction later than the other.

A working machine includes a machine body, a left traveling device located left on the machine body, a right traveling device located right on the machine body, and a controller configured or programmed to perform automatic deceleration to automatically reduce a first rotation speed of a left traveling motor and a second rotation speed of a right traveling motor by shifting a speed stage of each of the left and right traveling motors from a second speed stage to a first speed stage that is lower than the second speed stage. The controller is configured or programmed to: not perform the automatic deceleration when the first rotation speed or the second rotation speed is equal to or higher than a predetermined rotation speed; and perform the automatic deceleration when the first rotation speed and the second rotation speed are less than the predetermined rotation speed.

A working machine includes a prime mover, a traveling device, a traveling motor, a traveling pump, a circulation fluid passage, a traveling switching valve shiftable between a first state corresponding to a first speed of a hydraulic motor and a second state corresponding to a second speed of the hydraulic motor, a brake, an actuation valve configured to output the hydraulic pressure applied to the traveling pump, and change the hydraulic pressure output therefrom, and a controller configured or programmed to control the traveling switching valve, the brake and the actuation valve, and being capable of activating a first mode. The controller is configured or programmed to, when activating the first mode, shift the brake into a braking state, shift the traveling switching valve into the second state, and control the actuation valve so as to set the hydraulic pressure output from the actuation valve to a predetermined pressure.

A working machine includes a controller configured or programmed to perform an automatic deceleration for automatically decelerating a left traveling motor and a right traveling motor rotated at a second speed by shifting from the second speed to the first speed, and to determine a deceleration threshold that is used for judging whether the automatic deceleration has to be performed or not.

A hydraulic system for a working machine includes a hydraulic pump to output a hydraulic fluid, an operation device operable to supply a pilot fluid in accordance with an amount by which the operation device is operated, a hydraulic actuator to be operated by the hydraulic fluid, a pilot fluid passage connected to the operation device, a first control valve connected to the pilot fluid passage and to be operated by the pilot fluid to control a flow of the hydraulic fluid, a second control valve to be operated by the pilot fluid to control a flow of the hydraulic fluid, a proportional valve to change a pressure of the pilot fluid to operate the second control valve, a pressure detector provided in the pilot fluid passage to detect a pressure in the pilot fluid passage, and a controller to control the proportional valve based on the pressure.

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Osaka, Japan

Kohei Nagao