Steering device

1. A steering device comprising:

a steering mechanism including a steering shaft, and a transmitting mechanism,

the steering shaft including a first shaft, a second shaft, and a torsion bar provided between the first shaft and the second shaft, and

the transmitting mechanism configured to transmit a rotation of the steering shaft to a steered wheel;

a power cylinder including a power cylinder main body portion, a piston, and a first hydraulic chamber, and a second hydraulic chamber,

the power cylinder configured to provide a steering force for steering the steered wheel, to the transmitting mechanism, and

the piston which is provided within the power cylinder main body portion, and which separates an inside space of the power cylinder main body portion into the first hydraulic chamber and the second hydraulic chamber;

a first electric motor which includes a stator coil, and a motor rotor, and which is configured to provide a rotation force to the first shaft;

a first pump configured to be driven by a first driving source, and to discharge a hydraulic fluid;

a second pump configured to be driven by a second electric motor which is a second driving source, and to discharge the hydraulic fluid;

a rotary valve configured to selectively supply the hydraulic fluid supplied from the first pump or the second pump, to the first hydraulic chamber and the second hydraulic chamber in accordance with a torsion of the torsion bar; and

a controller including a first hydraulic passage state judging section, a first electric motor control section, and a second electric motor control section;

the first hydraulic passage state judging section configured to judge a state of the hydraulic fluid in a first hydraulic passage in which the hydraulic fluid discharged from the first pump flows,

the first electric motor control section configured to:

control and drive the first electric motor based on a driving state of a vehicle,

receive input of a rotation speed of the second electric motor, and

control and drive the first electric motor in accordance with the rotation speed of the second electric motor, and

the second electric motor control section configured to increase a rotation number of the second electric motor when the first hydraulic passage state judging section judges that a supply of the hydraulic fluid in the first hydraulic passage is deficient.

2. The steering device as claimed in claim 1 , wherein the first hydraulic passage state judging section is configured to judge whether or not the abnormality is generated in the first hydraulic passage based on a pressure of the hydraulic fluid in the first hydraulic passage; and

the second electric motor control section is configured to increase the rotation number of the second electric motor when the first hydraulic passage state judging section judges that the abnormality is generated in the first hydraulic passage.

3. The steering device as claimed in claim 2 , wherein the steering device includes a switching valve;

the switching valve is provided between the first pump and the second pump, and the rotary valve;

the switching valve includes a valve housing, and a valve element configured to be moved within the valve housing;

the valve element is configured to be moved to a first position when the pressure of the hydraulic fluid discharged from the first pump, and supplied to the switching valve is equal to or greater than a first predetermined value, and to be moved to a second position when the pressure of the hydraulic fluid discharged from the first pump, and supplied to the switching valve is smaller than the first predetermined value; and

the switching valve is configured to supply the hydraulic fluid discharged from the first pump to the rotary valve when the valve element is positioned at the first position, and to supply the hydraulic fluid discharged from the second pump to the rotary valve when the valve element is positioned at the second position.

4. The steering device as claimed in claim 3 , wherein the switching valve includes a first sensing switch;

the first sensing switch is configured to sense that the valve element is positioned at the second position; and

the first hydraulic passage state judging section is configured to judge that the abnormality is generated in the first hydraulic passage when the first sensing switch senses that the valve element is positioned at the second position.

5. The steering device as claimed in claim 3 , wherein the steering device includes a second sensing switch;

the switching valve includes a first sensing switch;

the first sensing switch is configured to sense that the valve element is positioned at the second position; and

the second sensing switch is configured to sense that the hydraulic pressure of the hydraulic fluid discharged from the first pump, and supplied to the switching valve becomes smaller than a second predetermined value higher than the first predetermined value; and

the first hydraulic passage state judging section is configured to judge that the abnormality is generated in the first hydraulic passage when the second sensing switch senses that the hydraulic pressure of the hydraulic fluid supplied from the first pump to the switching valve becomes smaller than the second predetermined value.

6. The steering device as claimed in claim 3 , wherein the steering device includes a pressure sensor;

the pressure sensor includes an element configured to sense a variation of the hydraulic pressure of the hydraulic fluid discharged from the first pump, and supplied to the switching valve; and

the first hydraulic passage state judging section is configured to judge that the abnormality is generated in the first hydraulic passage when the pressure sensor senses that the hydraulic pressure of the hydraulic fluid supplied from the first pump to the switching valve becomes smaller than a third predetermined value.

7. The steering device as claimed in claim 1 , wherein the first electric motor control section is configured to control and drive the first electric motor to increase a drive torque of the first electric motor when the steering force of the power cylinder is deficient; and

the first hydraulic passage state judging section is configured to judge that the supply of the hydraulic fluid in the first hydraulic passage is deficient when the drive torque of the first electric motor is equal to or greater than a predetermined torque, or when a current value flowing in the first electric motor is equal to or greater than a predetermined current value.

8. The steering device as claimed in claim 1 , wherein the controller includes a lane deviation judging section;

the lane deviation judging section is configured to judge whether or not the vehicle is deviated from a traveling lane, or whether or not the vehicle may be deviated from the traveling lane; and

the first hydraulic passage state judging section is configured to judge that the supply of the hydraulic fluid in the first hydraulic passage is deficient when the lane deviation judging section judges that the vehicle is deviated from the traveling lane, or that the vehicle may be deviated from the traveling lane.

9. The steering device as claimed in claim 1 , wherein the controller is configured to receive a steered angle command signal which is a command signal for steering the steered wheel to a predetermined steered angle, and to receive an actual steered angle signal which is a signal relating to a sensed steering angle information of the steered wheel;

the first electric motor control section is configured to control and drive the first electric motor based on the steered angle command signal;

the first hydraulic passage state judging section is configured to judge that the supply of the hydraulic fluid in the first hydraulic passage is deficient when a difference between a value of the steered angle command signal and a value of the actual steered angle signal is not converged to be smaller than a predetermined value during a predetermined time period.

10. The steering device as claimed in claim 1 , wherein the first electric motor control section is configured to control and drive the first electric motor when the second electric motor control section controls and drives the second electric motor to increase the rotation number of the second electric motor.

11. The steering device as claimed in claim 1 , wherein the first electric motor control section is configured to control and drive the first electric motor in accordance with a vehicle speed.

12. The steering device as claimed in claim 11 , wherein the first electric motor control section is configured to control and drive the first electric motor so that a drive torque of the first electric motor is lower as a vehicle speed is higher.

13. The steering device as claimed in claim 1 , wherein the first electric motor control section is configured to control and drive the first electric motor so that a drive torque of the first electric motor is lower as the rotation speed of the second electric motor is higher.

14. The steering device as claimed in claim 1 , wherein the first driving source is an engine of the vehicle.

15. The steering device as claimed in claim 14 , wherein the second electric motor control section is configured to increase the rotation number of the second electric motor in a state in which a vehicle speed is equal to or smaller than a predetermined vehicle speed, and in an idling stop state in which the engine of the vehicle is stopped.

16. The steering device as claimed in claim 15 , wherein the first electric motor control section is configured to control and drive the first electric motor in the idling stop state.

17. The steering device as claimed in claim 14 , wherein the first electric motor control section is configured to control and drive the first electric motor in a state in which a vehicle speed is equal to or smaller than a predetermined vehicle speed, and in an idling stop state in which the engine of the vehicle is stopped;

the controller includes an engine start signal transmitting section; and

the engine start signal transmitting section is configured to transmit an engine start signal for starting the engine when a drive torque of the first electric motor is equal to or greater than a predetermined torque, or when a current value flowing in the first electric motor is equal to or greater than a predetermined current value, in the idling stop state.