Work vehicle

Patent metadata

Field	Value
Publication number	US-10960925-B2
Application number	US-201615576025-A
Country	US
Kind code	B2
Filing date	Mar 4, 2016
Priority date	May 25, 2015
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

A work vehicle includes an engine mounted on a traveling body, a straight-traveling system transmission path including a first stepless transmission device, and a turning system transmission path including a second stepless transmission device, the work vehicle being configured to combine outputs of the straight-traveling system transmission path and an output of the turning system transmission paths to drive left and right traveling units. The work vehicle also includes control sections that control the outputs of the straight-traveling system transmission path and the output of the turning system transmission paths in cooperation with each other, a transmission operation tool that specifies the output of the straight-traveling system transmission path, and a detector that detects the output of the straight-traveling system transmission path. The control sections select one of an instruction value from the transmission operation tool and an actually measured value from the detector and set the output of the turning system transmission path.

First claim

The invention claimed is:

1. A work vehicle including an engine that is mounted on a vehicle body, a straight-traveling system transmission path including a first stepless transmission, and a turning system transmission path including a second stepless transmission, the work vehicle being configured to combine an output of the straight-traveling system transmission path and an output of the turning system transmission path to drive left and right traveling units, the work vehicle comprising:
a controller configured to control the output of the straight-traveling system transmission path and the output of the turning system transmission path in cooperation with each other;
a transmission sensor configured to output an instruction value of the straight-traveling system transmission path; and
a detector configured to detect a measured value of the straight-traveling system transmission path,
wherein the controller is configured to select one of:
the instruction value from the transmission sensor, and
the measured value from the detector to set the output of the turning system transmission path.

2. The work vehicle according to claim 1 , wherein:
the straight-traveling system transmission path includes a forward-reverse switching mechanism,
the forward-reverse switching mechanism includes a reverse clutch, a forward low-speed clutch, and a forward high-speed clutch, and
when switching between the reverse clutch and the forward low-speed clutch, the controller is configured to perform control in such a manner that one of the reverse clutch and the forward low-speed clutch is constantly engaged.

3. The work vehicle according to claim 2 , wherein the work vehicle is configured such that, in a case where each of the clutches is disengaged in traveling, the output of the turning system transmission path is set in accordance with the measured value from the detector.

4. The work vehicle according to claim 2 , wherein:
in a case where a brake is operated in traveling, the controller is configured to set the output of the turning system transmission path in accordance with the measured value from the detector, and
the controller is configured to control the clutches in such a manner that each of the clutches is disengaged in a high-speed range where a traveling speed is a predetermined speed or more, and one of the reverse clutch and the forward low-speed clutch or one of the forward low-speed clutch and the forward high-speed clutch is engaged in a low-speed range where the traveling speed is less than the predetermined speed.

5. The work vehicle according to claim 1 , further comprising:
a transmission lever; and
wherein the transmission sensor is configured to detect an operation position of the transmission lever and to specify the output of the straight-traveling system transmission path based on the detected operation position.

6. A work vehicle comprising:
a first stepless transmission configured for straight traveling;
a second stepless transmission configured for turning the work vehicle;
a main transmission sensor configured to:
detect a position of a lever for specifying an instruction value of the first stepless transmission; and
output the instruction value;

a second sensor configured to detect a measured value of an output of the first stepless transmission; and
a controller configured to set an output of the second stepless transmission based on selecting one of:
the instruction value output by the main transmission sensor; and
the measured value from the second sensor.

7. The work vehicle of claim 6 , wherein the controller is further configured to:
calculate a target value based on the instruction value; and
set the output of the second stepless transmission based on selecting one of:
the target value; and
the measured value from the second sensor.

8. The work vehicle of claim 7 , wherein the controller is further configured to compare the measured value to the target value.

9. The work vehicle of claim 6 , wherein the controller is further configured to:
combine the output of the second stepless transmission and the output of the first stepless transmission to drive left and right traveling units; and
control the output of the first stepless transmission and the output of the second stepless transmission in cooperation with each other.

10. The work vehicle of claim 6 , further comprising:
a reverse clutch;
a forward low-speed clutch; and
a forward high-speed clutch.

11. The work vehicle of claim 10 , further comprising:
a forward-reverse movement sensor; and
wherein, the controller is further configured to, based on receiving a signal from the forward-reverse movement sensor, switch between the reverse clutch and the forward low-speed clutch in such a manner that one of the reverse clutch or the forward low-speed clutch is constantly engaged.

12. The work vehicle of claim 11 , further comprising:
a switching lever; and
wherein the controller is configured to, based on the switching lever being in a neutral position, set the output of the second stepless transmission based on the measured value.

13. The work vehicle of claim 12 , wherein each of the reverse clutch, the forward low-speed clutch, and the forward high-speed clutch are disengaged while the switching lever is in a neutral position.

14. The work vehicle of claim 11 , further comprising:
a brake pedal; and
wherein the controller is configured to, while the brake pedal is in a pressed state, set the output of the second stepless transmission based on the measured value.

15. The work vehicle of claim 14 , wherein the controller is configured to, while the brake pedal is in a pressed state:
control the forward low-speed clutch, and the forward high-speed clutch in such a manner that each of the clutches are disengaged in a high-speed range; and
control the forward low-speed clutch or the reverse clutch such that one of the clutches is engaged in a low speed range.

16. The work vehicle of claim 15 , wherein:
the high speed range corresponds to the traveling speed being greater than equal to a predetermined speed; and
the low speed range corresponds to the traveling speed being less than the predetermined speed.

17. The work vehicle according to claim 6 , further comprising the lever.

18. A control system for a work vehicle, the control system comprising:
a controller configured to:
receive, from a main transmission sensor, an instruction value of a first stepless transmission configured for straight traveling based on an operation position of a lever for specifying the instruction value, the operation position detected by the main transmission sensor;
receive, from a second sensor, a measured value of an output of the first stepless transmission; and
set an output of a second stepless transmission configured for turning the work vehicle based on selecting one of:
the instruction value received by the controller; and
the measured value from the second sensor.

19. The control system of claim 18 , wherein the controller is further configured to:
calculate a target value based on the instruction value;
compare the measured value to the target value; and
set the output of the second stepless transmission based on selecting one of:
the target value; and
the measured value from the second sensor.

20. The control system of claim 18 , further comprising the lever.

Assignees

• Yanmar Power Technology Co Ltd

Inventors

• Fujiki Katsumi
• Iwamura Keisuke

Classifications

• B62D11/18

  the additional power supply being supplied hydraulically · CPC title

• B62D11/003 Primary

  Electric or electronic control systems · CPC title

• B62D11/08 Primary

  using brakes or clutches as main steering-effecting means · CPC title

• B62D11/10

  using gearings with differential power outputs on opposite sides, e.g. twin-differential or epicyclic gears · CPC title

• B62D11/005

  Hydraulic control systems · CPC title