System and method for controlling power transmission mechanism, and utility vehicle

1. A system for controlling a power transmission mechanism, the system comprising:

a power transmission mechanism including a rotation shaft, a power transmission gear rotatably fitted to the rotation shaft and locked to the rotation shaft with respect to an axial direction, a dog ring slidably fitted to the rotation shaft so as to be slidable in the axial direction and locked to the rotation shaft with respect to a circumferential direction, and a dog clutch in the dog ring and the power transmission gear;

a switching mechanism configured to move the dog ring in the axial direction to switch a power transmission state; and

a switching controller configured to control an operation of the switching mechanism, and the switching controller being further configured to:

determine whether the dog clutch is in an engaged state when a switching command is given to the switching mechanism to switch the power transmission state by moving the dog ring in the axial direction to a side of the power transmission gear, and

after determining that the dog clutch is not in the engaged state, control the switching mechanism to move the dog ring in the axial direction to a side opposite to the power transmission gear, and then control the switching mechanism to retry movement of the dog ring to the side of the power transmission gear.

2. The system for controlling a power transmission mechanism according to claim 1 , wherein the switching mechanism includes:

a shift member configured to engage with the dog ring to move the dog ring in the axial direction;

a pump configured to supply fluid pressure;

a piston configured to move the shift member in the axial direction in accordance with the fluid pressure supplied by the pump; and

a valve configured to adjust the fluid pressure supplied to the piston, and

wherein the switching controller is configured to generate a fluid pressure adjustment command to the valve for adjusting the fluid pressure to cause the shift member to be moved and thereby cause the dog ring to be moved in the axial direction.

3. The system for controlling a power transmission mechanism according to claim 1 , further comprising an operation sensor configured to detect an operation of the dog ring,

wherein the switching controller is configured to determine whether the dog clutch is in the engaged state based on the operation of the dog ring detected by the operation sensor.

4. The system for controlling a power transmission mechanism according to claim 3 , wherein:

the switching mechanism includes an operation portion configured to operate in conjunction with the dog ring, and

the operation sensor is a contact position sensor to be brought into contact with the operation portion to detect a position of the dog ring.

5. The system for controlling a power transmission mechanism according to claim 3 , further comprising a rotation speed sensor configured to detect a rotation speed difference between the dog ring and the power transmission gear,

wherein the switching controller is configured to determine whether the dog clutch is in the engaged state based on the operation of the dog ring detected by the operation sensor and the rotation speed difference detected by the rotation speed sensor.

6. The system for controlling a power transmission mechanism according to claim 1 , further comprising a rotation speed sensor configured to detect a rotation speed difference between the dog ring and the power transmission gear,

wherein the switching controller is configured to determined whether the dog clutch is in the engaged state based on the rotation speed difference detected by the rotation speed sensor.

7. The system for controlling a power transmission mechanism according to claim 1 , wherein the switching controller is configured to change a phase of the dog ring with respect to the power transmission gear when the dog clutch is determined not to be in the engaged state.

8. The system for controlling a power transmission mechanism according to claim 7 , further comprising:

a drive source; and

a drive wheel to which power from the drive source is transmitted through the dog ring and the power transmission gear,

wherein the switching controller is configured to change a rotation speed of one of the dog ring and the power transmission gear located closer to the drive source when changing the phase.

9. A method for controlling a power transmission mechanism including a rotation shaft, a power transmission gear rotatably fitted to the rotation shaft and locked to the rotation shaft with respect to an axial direction, a dog ring slidably fitted to the rotation shaft so as to be slidable in the axial direction and locked to the rotation shaft with respect to a circumferential direction, and a dog clutch in the dog ring and the power transmission gear, the method comprising:

determining whether the dog clutch is in an engaged state when a switching command is given to switch a power transmission state by moving the dog ring in the axial direction to a side of the power transmission gear; and

after determining that the dog clutch is not in the engage state, moving the dog ring in the axial direction to a side opposite to the power transmission gear, and then retrying movement of the dog ring to the side of the power transmission gear.

10. A utility vehicle comprising:

a rotation shaft;

a power transmission gear rotatably fitted to the rotation shaft and locked to the rotation shaft with respect to an axial direction;

a dog ring slidably fitted to the rotation shaft so as to be slidable in the axial direction and locked to the rotation shaft with respect to a circumferential direction;

a dog clutch in the dog ring and the power transmission gear;

a shift member engaged with the dog ring and configured to move the dog ring in the axial direction; and

a controller configured to control movement of the shift member, the controller being further configured to:

determine whether the dog clutch is in an engaged state when a switching command is given to switch a power transmission state by moving the dog ring in the axial direction to a side of the power transmission gear, and

after determining that the dog clutch is not in the engaged state, control the shift member to move the dog ring in the axial direction to a side opposite to the power transmission gear, and then retry movement of the dog ring to the side of the power transmission gear.