Work vehicle and control method for work vehicle

Patent metadata

Field	Value
Publication number	US-12180683-B2
Application number	US-201816476646-A
Country	US
Kind code	B2
Filing date	May 29, 2018
Priority date	Jun 27, 2017
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

A work vehicle includes an engine, a hydrostatic transmission, a work implement pump driven by the engine, a work implement driven by hydraulic fluid discharged from the work implement pump, an accelerator, a first sensor configured to output a signal indicative of an operation amount of the accelerator, a work implement operating member, a second sensor configured to output a signal indicative of an operation amount of the work implement operating member, and a controller. The controller is configured to receive signals from the first sensor and the second sensor, determine a target input horsepower input to the hydrostatic transmission from the operation amount of the accelerator, and determine a target rotational speed of the engine from the target input horsepower and the operation amount of the work implement operating member.

First claim

The invention claimed is:

1. A work vehicle comprising:
an engine;
a hydrostatic transmission including a traveling pump driven by the engine, a hydraulic circuit connected to the traveling pump, and a traveling motor connected to the traveling pump via the hydraulic circuit;
a work implement pump driven by the engine;
a work implement driven by hydraulic fluid discharged from the work implement pump;
an accelerator;
a first sensor configured to output a signal indicative of an operation amount of the accelerator;
a work implement operating member;
a second sensor configured to output a signal indicative of an operation amount of the work implement operating member; and
a controller configured to
receive signals from the first sensor and the second sensor,
determine a target input horsepower input to the hydrostatic transmission from the operation amount of the accelerator, and
determine a target rotational speed of the engine from the target input horsepower and the operation amount of the work implement operating member.

2. The work vehicle according to claim 1 , wherein
the controller is further configured to
determine a first target rotational speed from the target input horsepower,
determine a second target rotational speed from the operation amount of the work implement operating member, and
determine the target rotational speed of the engine from the first target rotational speed and the second target rotational speed.

3. The work vehicle according to claim 2 , wherein
the controller is further configured to determine a larger one of the first target rotational speed and the second target rotational speed as the target rotational speed of the engine.

4. The work vehicle according to claim 1 , wherein
the controller is further configured to
determine a target traction force in stalling from the operation amount of the accelerator, and
determine the target input horsepower from the target traction force in stalling when the work vehicle is in a stall state.

5. The work vehicle according to claim 4 , wherein
the controller is further configured to
determine a target vehicle speed from the operation amount of the accelerator,
determine a target traveling horsepower from the target vehicle speed, and
determine the target input horsepower from a target stall horsepower and the target traveling horsepower when the vehicle speed is within a predetermined first speed range in which the vehicle speed is higher than a speed range in stalling.

6. The work vehicle according to claim 5 , wherein
the controller is further configured to decrease the target input horsepower according to an increase of the target vehicle speed when the vehicle speed is within a predetermined second speed range in which the vehicle speed is higher than the first speed range and including a maximum vehicle speed.

7. The work vehicle according to claim 1 , wherein
the controller is further configured to
determine a target vehicle speed from the operation amount of the accelerator,
determine a target traction force from the operation amount of the accelerator, and
determine the target input horsepower from the target vehicle speed and the target traction force.

8. The work vehicle according to claim 5 , further comprising:
a vehicle speed sensor that outputs a signal indicative of an actual vehicle speed of the work vehicle,
the controller being further configured to
receive a signal from the vehicle speed sensor,
determine a target reference vehicle speed from the operation amount of the accelerator,
determine a target acceleration from the operation amount of the accelerator and a difference between the target reference vehicle speed and the actual vehicle speed, and
determine the target vehicle speed from the actual vehicle speed and the target acceleration.

9. The work vehicle according to claim 8 , wherein
the controller is further configured to determine the target vehicle speed depending on whether the work vehicle is accelerating or decelerating.

10. The work vehicle according to claim 8 , further comprising:
a shift operating member usable to select a maximum vehicle speed;
a shift operation sensor configured to output a signal indicative of the maximum vehicle speed selected by the shift operating member; and
a storage device storing reference vehicle speed data indicative of a relationship between the operation amount of the accelerator and the target reference vehicle speed with respect to the maximum vehicle speed,
the controller being further configured to determine the target reference vehicle speed corresponding to the selected maximum vehicle speed from the operation amount of the accelerator with reference to the reference vehicle speed data.

11. The work vehicle according to claim 1 , further comprising:
an input device usable to set a traction control to select a maximum traction force from a plurality of traction levels,
the controller being further configured to
receive a signal indicative of the selected traction level from the input device,
determine a target traction force in stalling from the operation amount of the accelerator, and
determine a target traction force in the traction control by multiplying the target traction force in stalling by a ratio according to the traction level.

12. The work vehicle according to claim 1 , wherein
the controller is further configured to
determine a first target rotational speed from the target input horsepower,
determine a second target rotational speed from the operation amount of the work implement operating member,
determine a target vehicle speed from the operation amount of the accelerator,
determine a third target rotational speed for the vehicle speed from the target vehicle speed, and
determine the target rotational speed of the engine from the first target rotational speed, the second target rotational speed, and the third target rotational speed.

13. The work vehicle according to claim 12 , wherein
the controller is further configured to determine a largest of the first target rotational speed, the second target rotational speed, and the third target rotational speed as the target rotational speed of the engine.

14. A method executed by a controller in order to control a work vehicle including an engine, a hydrostatic transmission connected to the engine, a work implement pump connected to the engine, and a work implement driven by hydraulic fluid discharged from the work implement pump, the method comprising:
receiving a signal indicative of an operation amount of an accelerator;
receiving a signal indicative of an operation amount of a work implement operating member;
determining a target input horsepower input to the hydrostatic transmission from the operation amount of the accelerator; and
determining a target rotational speed of the engine from the target input horsepower and the operation amount of the work implement operating member.

Assignees

• Komatsu Mfg Co Ltd

Inventors

• Oasa Takahisa

Classifications

• F16H63/50

  Signals to an engine or motor · CPC title

• F16H61/475

  for achieving a target power, e.g. input power or output power · CPC title

• F16H61/431

  Pump capacity control by electro-hydraulic control means, e.g. using solenoid valves · CPC title

• F16H59/18

  dependent on the position of the accelerator pedal · CPC title

• F16H59/04

  Ratio selector apparatus · CPC title