Vehicle steering device

1. A vehicle steering device comprising:

a control unit that determines a turning angle of wheels of a vehicle in accordance with a steering angle of a steering wheel, the steering wheel being provided in the vehicle and mechanically disconnected from the wheels,

wherein, when a state of a switch that starts a driving unit of the vehicle is switched from an ON state to an OFF state, the control unit determines whether or not a previous vehicle speed is higher than a predetermined speed

wherein, if the previous vehicle speed is higher than the predetermined speed, the control unit continuously turns ON a power supply of the vehicle steering device regardless of a current vehicle speed until a predetermined time elapses, and turns OFF the power supply of the vehicle steering device after the predetermined time elapses, and

wherein, if the previous vehicle speed is not higher than the predetermined speed, the control unit turns OFF the power supply of the vehicle steering device.

2. The vehicle steering device according to claim 1 , wherein the control unit calculates the predetermined time in accordance with the previous vehicle speed, and a previous driving state and/or a previous driving environment of the vehicle.

3. The vehicle steering device according to claim 1 ,

wherein the control unit determines whether or not the predetermined time has elapsed after the state of the switch is switched from the ON state to the OFF state, and

wherein the control unit stops determining whether or not the predetermined time has elapsed if the state of the switch is switched from the OFF state to the ON state while the control unit determines whether or not the predetermined time has elapsed.

4. The vehicle steering device according to claim 1 , wherein the previous vehicle speed is a vehicle speed of the vehicle just before switching of the switch from the ON state to the OFF state.

5. The vehicle steering device according to claim 2 , wherein the previous driving state includes a road on which the vehicle runs is flat, uphill, or downhill.

6. The vehicle steering device according to claim 2 , wherein the previous driving environment includes a road on which the vehicle runs is whether a highway or an ordinary road, or whether the road is straight or curved.

7. The vehicle steering device according to claim 1 , wherein if the previous vehicle speed is not higher than the predetermined speed, the control unit immediately turns OFF the power supply of the vehicle steering device.

8. The vehicle steering device according to claim 1 , wherein the driving unit is an internal combustion engine.

9. The vehicle steering device according to claim 1 , wherein the driving unit is a driving motor.

10. A vehicle comprising the vehicle steering device according to claim 1 .

11. A vehicle steering device comprising:

a steering wheel provided in a vehicle and mechanically disconnected from wheels of the vehicle,

a controller that determines a turning angle of the wheels of the vehicle in accordance with a steering angle of the steering wheel,

wherein the controller detects a state of a switch that starts a driving unit of the vehicle is switched from an ON state to an OFF state, and when the state of the switch is switched from the ON state to the OFF state, the controller determines whether or not a previous vehicle speed is higher than a predetermined speed,

wherein, if the previous vehicle speed is higher than the predetermined speed, the controller continuously turns ON a power supply of the vehicle steering device regardless of a current vehicle speed until a predetermined time elapses, and turns OFF the power supply of the vehicle steering device after the predetermined time elapses, and

wherein, if the previous vehicle speed is not higher than the predetermined speed, the controller turns OFF the power supply of the vehicle steering device.

12. A method of controlling a vehicle steering device comprising an electronic control unit that determines a turning angle of wheels of a vehicle in accordance with a steering angle of a steering wheel, the steering wheel being provided in the vehicle and mechanically disconnected from the wheels, the method comprising:

detecting by using the electronic control unit, a state of a switch that starts a driving unit of the vehicle is switched from an ON state to an OFF state, and when the state of the switch is switched from the ON state to the OFF state, determining whether or not a previous vehicle speed is higher than a predetermined speed,

if the previous vehicle speed is higher than the predetermined speed, continuously turning ON a power supply of the vehicle steering device regardless of a current vehicle speed until a predetermined time elapses, and turning OFF the power supply of the vehicle steering device after the predetermined time elapses, and

if the previous vehicle speed is not higher than the predetermined speed, turning OFF the power supply of the vehicle steering device.