Utility vehicle

1. A utility vehicle comprising:

a plurality of wheels;

a differential device configured to be switchable between an open state in which a driving force is distributed to the plurality of wheels and a locked state in which the plurality of wheels are directly connected;

a brake device that brakes the plurality of wheels;

a stack sensor for detecting whether a stack is generated in the vehicle; and

a controller configured to:

determine whether a stack is generated in the vehicle based on a detection result of the stack sensor when the differential device is in the open state; and

operate, when it is determined that the stack has occurred, at least the brake device to decrease a rotation speed of a stack wheel which is a wheel that is idling.

2. The utility vehicle according to claim 1 , wherein, when determining that the stack has occurred, the controller operates the brake device until the stack sensor detects a stop of the stack wheel.

3. The utility vehicle according to claim 1 , wherein, when the stack sensor detects a stop of the stack wheel after determining that the stack has occurred, the controller sets a traveling mode to a stack exit mode.

4. The utility vehicle according to claim 3 , wherein the controller switches the differential device from the open state to the locked state in the stack exit mode.

5. The utility vehicle according to claim 3 , further comprising a two-wheel drive/four-wheel drive switching mechanism that switches between a two-wheel drive state in which the driving force is transmitted to any two of two front wheels and two rear wheels included in the plurality of wheels and a four-wheel drive state in which the driving force is transmitted to all of the two front wheels and the two rear wheels,

wherein the controller operates the two-wheel drive/four-wheel drive switching mechanism to set the four-wheel drive state in the stack exit mode.

6. The utility vehicle according to claim 5 , wherein the controller sets the four-wheel drive state and switches the differential device from the open state to the locked state in the stack exit mode.

7. The utility vehicle according to claim 3 , further comprising an information presentation device that presents information to the driver,

wherein the controller causes the information presentation device to present information for guiding an operation for stack exit in the stack exit mode.

8. The utility vehicle according to claim 3 , further comprising:

an accelerator operation member operated by a driver to adjust the driving force; and

an accelerator operation amount sensor that detects an operation amount of the accelerator operation number,

wherein the controller reduces the driving force generated according to the operation amount of the accelerator operation member in the stack exit mode as compared with a normal traveling mode.

9. The utility vehicle according to claim 3 , further comprising a plurality of suspension devices individually provided on the plurality of wheels, the suspension devices having variable strokes,

wherein, in the stack exit mode, the controller operates the suspension device corresponding to the stack wheel such that the stroke is extended.

10. The utility vehicle according to claim 3 , wherein the controller ends the stack exit mode when determining an exit of the vehicle from the stack based on a detection result of the stack sensor after setting the stack mode.

11. The utility vehicle according to claim 10 , wherein the controller ends the stack exit mode when a vehicle speed becomes equal to or larger than a predetermined threshold value.

12. The utility vehicle according to claim 1 , wherein the controller controls the driving force to generate an engine braking force when determining that the stack has occurred.

13. The utility vehicle according to claim 1 , further comprising:

an accelerator operation member operated by a driver to adjust the driving force; and

an accelerator operation amount sensor that detects an operation amount of the accelerator operation member,

wherein, when determining that the stack has occurred, the controller reduces the driving force generated according to the operation amount of the accelerator operation member than a normal driving force and activates the brake device.

14. The utility vehicle according to claim 1 , further comprising:

an accelerator operation member operated by a driver to adjust the driving force; and

an accelerator operation amount sensor that detects an operation amount of the accelerator operation member,

wherein, when determining that the stack has occurred, the controller determines that the accelerator operation member is unoperated based on a detection result by the accelerator operation amount sensor, and then operates the brake device.

15. The utility vehicle according to claim 14 , wherein the controller returns a traveling mode to a normal traveling mode when determining that the vehicle can travel before the accelerator operation member is unoperated after determining that the stack has occurred.

16. The utility vehicle according to claim 1 ,

wherein the brake device is configured to be able to brake the plurality of wheels individually, and

the controller is configured to:

specify, when determining that the stack has occurred, the stack wheel from the plurality of wheels; and

operate the brake device such that a braking force is applied only to the specified stack wheel.

17. The utility vehicle according to claim 1 , wherein the stack sensor includes a wheel speed sensor that detects a rotation speed of each of the plurality of wheels.

18. The utility vehicle according to claim 17 ,

wherein the stack sensor includes a vehicle body speed sensor that detects a ground speed of a vehicle body of the vehicle, and

the vehicle body speed sensor includes at least one of a receiver of a satellite positioning system and an inertial measurement unit.