Utility vehicle

1. A utility vehicle comprising:

a pair of front wheels;

a pair of rear wheels;

at least one front wheel power source configured to drive the front wheels and not to drive the rear wheels;

at least one rear wheel power source configured to drive the rear wheels and not to drive the front wheels; and

a controller that controls the front wheel power source and the rear wheel power source, wherein

upon receiving a predetermined two-wheel drive command, the controller brings the front wheel power source into a non-operative state while allowing the rear wheel power source to drive the rear wheels,

upon receiving a predetermined four-wheel drive command, the controller brings the front wheel power source into operation while allowing the rear wheel power source to drive the rear wheels, and

upon receiving a predetermined specific travel command, the controller temporarily causes the front wheel power source to operate until a predetermined front wheel drive stopping condition is satisfied, even when the two-wheel drive command is received.

2. The utility vehicle according to claim 1 , wherein

the front wheel power source comprises an electric motor, and

the rear wheel power source comprises an engine.

3. The utility vehicle according to claim 2 , wherein the controller brings the electric motor into a regeneration state upon receiving a predetermined deceleration command, regardless of which of the two-wheel drive command and the four-wheel drive command has been received.

4. The utility vehicle according to claim 2 , further comprising:

an electricity generator that generates electricity from power of the engine; and

an electricity storage device charged with electricity generated by the electricity generator, wherein

the electric motor is operated with electricity supplied from the electricity storage device.

5. The utility vehicle according to claim 1 , wherein

the pair of front wheels consists of a left front wheel and a right front wheel, and

the utility vehicle further comprises:

a left clutch configured to disable power transmission from the front wheel power source to the left front wheel;

a right clutch configured to disable power transmission from the front wheel power source to the right front wheel; and

a clutch actuator that actuates the left clutch and the right clutch.

6. The utility vehicle according to claim 1 , further comprising a differential gear device disposed between the front wheel power source and the pair of front wheels.

7. The utility vehicle according to claim 1 , further comprising a seat on which a user of the utility vehicle sits, wherein

the rear wheel power source is disposed rearwardly of the seat, and

the pair of rear wheels is supported by a swing arm.

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

a seat on which a user of the utility vehicle sits; and

a battery disposed below the seat, wherein

the front wheel power source or the rear wheel power source is an electric motor operated with electricity supplied from the battery.

9. The utility vehicle according to claim 1 , wherein the predetermined specific travel command includes a start command to start the vehicle from a stopped state.

10. The utility vehicle according to claim 9 , wherein the front wheel power source comprises an electric motor.

11. The utility vehicle according to claim 9 , wherein the front wheels are steering wheels.

12. The utility vehicle according to claim 9 , wherein the front wheels are steering wheels, and the front wheel power source comprises an electric motor.

13. The utility vehicle according to claim 1 , wherein the controller causes the front wheel power source to operate until a vehicle speed crosses a predetermined threshold, if an acceleration command is detected when the vehicle speed is lower than a predetermined value.

14. The utility vehicle according to claim 1 , further comprising a transmission that provides a rotational speed change of power generated by the rear wheel power source, wherein the controller causes the front wheel power source to operate until a gear ratio of the transmission crosses a predetermined threshold on a high-speed side, if an acceleration command is detected when a vehicle speed is lower than a predetermined value.

15. The utility vehicle according to claim 1 , wherein

the front wheel power source comprises an electric motor, and

upon receiving a predetermined deceleration command, the controller brings the electric motor into a regeneration state.

16. A utility vehicle comprising:

a pair of front wheels that consists of a left front wheel and a right front wheel;

a pair of rear wheels;

at least one front wheel power source configured to drive the front wheels and not to drive the rear wheels;

at least one rear wheel power source configured to drive the rear wheels and not to drive the front wheels;

a controller that controls the front wheel power source and the rear wheel power source;

a left clutch configured to disable power transmission from the front wheel power source to the left front wheel;

a right clutch configured to disable power transmission from the front wheel power source to the right front wheel; and

a clutch actuator that actuates the left clutch and the right clutch, wherein

upon receiving a predetermined two-wheel drive command, the controller brings the front wheel power source into a non-operative state while allowing the rear wheel power source to drive the rear wheels,

upon receiving a predetermined four-wheel drive command, the controller brings the front wheel power source into operation while allowing the rear wheel power source to drive the rear wheels,

the left clutch and the right clutch are clutches actuated by hydraulic pressure, and

the clutch actuator comprises:

a hydraulic pump driven by the rear wheel power source; and

a control valve unit configured to allow hydraulic pressure of the hydraulic pump to be applied to the left clutch and the right clutch.