Work vehicle and control method for work vehicle

Patent metadata

Field	Value
Publication number	US-10794043-B2
Application number	US-201716084390-A
Country	US
Kind code	B2
Filing date	Aug 25, 2017
Priority date	Aug 26, 2016
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A work vehicle includes a hydraulic actuator, a control valve, a pressure sensing unit, a force imparting component, and a controller. The hydraulic actuator varies a steering angle. The control valve controls flow of fluid supplied to the hydraulic actuator. The operation member is configured to be operated by an operator and to control the control valve when varying the steering angle. The pressure sensing unit senses a pressure produced by the hydraulic actuator. The force imparting component imparts an assisting force or a counterforce to operation of the operation member. The controller controls the force imparting component so as to generate resistance to operation of the operation member based on a pressure value sensed by the pressure sensing unit.

First claim

The invention claimed is:

1. A work vehicle, comprising:
a first hydraulic actuator and a second hydraulic actuator configured to vary a steering angle
the first hydraulic actuator contracting and the second hydraulic actuator expanding to change the steering angle toward a left side,
the second hydraulic actuator contracting and the first hydraulic actuator expanding to change the steering angle toward the right side;

a control valve configured to control flow of fluid supplied to the first and second hydraulic actuators;
an operation member mechanically linked to the control valve, the operation member being configured
to be operated by an operator and
to control the control valve when varying the steering angle;

a pressure sensing unit configured to sense a first pressure produced by the first hydraulic actuator and a second pressure produced by the second hydraulic actuator;
a force imparting component configured to impart an assisting force or a counterforce to operation of the operation member; and
a controller configured to control the force imparting component so as to generate a resistance to operation of the operation member based on the first pressure and the second pressure detected by the pressure sensing unit, the controller calculating a pressure difference between the first pressure and the second pressure and controlling the force imparting component such that the resistance becomes larger as the pressure difference increases.

2. The work vehicle according to claim 1 , wherein
the controller is further configured to generate resistance to operation of the operation member by decreasing the assisting force or increasing the counterforce produced by the force imparting component.

3. The work vehicle according to claim 1 , further comprising:
a front frame; and
a rear frame linked to the front frame at a linking shaft,
one of the first and second hydraulic actuators being disposed to the left and the other of the first and second hydraulic cylinders being disposed to the right, respectively, of the linking shaft along a vehicle width direction, and the first and second hydraulic actuators being configured to vary an angle of the front frame with respect to the rear frame.

4. The work vehicle according to claim 1 , further comprising:
a torque sensor configured to detect a torque generated by operation of the operation member,
the force imparting component having an electric motor, and
the controller being further configured to actuate the force imparting component based on the first pressure, the second pressure, and the torque.

5. The work vehicle according to claim 4 , further comprising:
a speed sensor configured to detect speed of the work vehicle,
the controller being further configured to actuate the force imparting component based on the speed in addition to the first pressure, the second pressure, and the torque.

6. The work vehicle according to claim 4 , wherein the controller includes
a calculator configured to calculate a force to be imparted to operation of the operation member by combining
a first imparted force set based on the torque, and
a second imparted force set based on the pressure; and

an actuation controller configured to actuate the force imparting component so as to impart the calculated force.

7. The work vehicle according to claim 1 , further comprising:
a steering valve configured to adjust flow of fluid supplied to the hydraulic actuator based on pilot pressure inputted from the control valve,
the control valve controlling the flow of fluid supplied from the steering valve to the hydraulic actuator by adjusting the pilot pressure.

8. A work vehicle, comprising:
a hydraulic actuator configured to vary a steering angle;
a control valve configured to control flow of fluid supplied to the hydraulic actuator;
an operation member configured
to be operated by an operator and
to control the control valve when varying the steering angle;

a pressure sensing unit configured to detect a pressure produced by the hydraulic actuator;
a force imparting component having an electric motor arranged and configured to impart an assisting force or a counterforce to operation of the operation member; and
a torque sensor configured to detect a torque generated by operation of the operation member;
a speed sensor configured to detect a speed of the work vehicle;
a target steering angle sensor configured to detect a target steering angle inputted with the operation member;
an actual steering angle sensor configured to detect the actual steering angle changed by the hydraulic actuators; and
a controller configured to control the force imparting component so as to generate resistance to operation of the operation member based on the pressure detected by the pressure sensing unit and the torque detected by the torque sensor,
the controller including
a calculator configured to calculate a force to be imparted to operation of the operation member by combining
a first imparted force that is set based on the torque detected by the torque sensor and the speed detected by the speed sensor, a first imparted force set based on the torque detected by the torque sensor and the speed detected by the speed sensor, and
a second imparted force that is set based on the pressure detected by the pressure sensing unit and a deviation angle calculated from the target steering angle detected by the target steering angle sensor and the actual steering angle detected by the actual steering angle sensor, and

an actuation controller configured to actuate the force imparting component so as to impart the calculated force.

9. The work vehicle according to claim 8 , wherein
the operating member is a joystick lever,
the control valve includes
a first input member configured to be displaced according to the target steering angle,
a second input member configured to be displaced according to the actual steering angle, and
a biasing component configured to bias the first input member so that displacement of the first input member matches displacement of the second input member,

a difference between the displacement of the first input member and the displacement of the second input member corresponds to the deviation angle between the target steering angle and the actual steering angle, and
the joystick lever is operated against biasing force of the biasing component.

10. A control method for a work vehicle, comprising:
acquiring a detection signal from a pressure sensing unit configured to detect a first pressure and a second pressure produced by a first hydraulic actuator and a second hydraulic actuator, respectively, the first and second hydraulic actuators being configured and arranged to vary a steering angle in response to an operating position of a control valve configured to control flow of fluid supplied to the first and second hydraulic actuators,
the first hydraulic actuator contracting and the second hydraulic actuator expanding to change the steering angle toward a left side,
the second hydraulic actuator contracting and the first hydraulic actuator expanding to change the steering angle toward the right side;

calculating a pressure difference between the first pressure and the second pressure;
based on the difference, generating a control signal to generate a resistance to operation of an operating member by an operator when varying the steering angle, the operating member being mechanically linked to the control valve, and the control signal being generated such that the resistance becomes larger as the pressure difference increases; and
transmitting the control signal to a force imparting component configured to impart an assisti

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Takenaka Yuita
• Ikari Masanori
• Nakabayashi Masanobu

Classifications

• B62D1/12 Primary

  Hand levers · CPC title

• B66F9/07586

  Suspension or mounting of wheels on chassis · CPC title

• B66F9/07568

  Steering arrangements · CPC title

• E02F9/16

  Cabins, platforms, or the like, for drivers ({for motor vehicles in general B62D33/06}, for cranes B66C13/54) · CPC title

• B62D12/00

  Steering specially adapted for vehicles operating in tandem or having pivotally connected frames (steering endless tracks or the like B62D11/00; steering specially adapted for trailers B62D13/00) · CPC title