Steer-by-wire steering system with road feel

• US 20040020706A1
• Filed: 01/06/2003
• Published: 02/05/2004
• Est. Priority Date: 04/03/2000
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Williams, Daniel E.
• Granted Patent: US 6,973,989 B2
• Time in Patent Office: Days
• US Class Current: 180/443
• CPC Class Codes: B62D 5/001 Mechanical components or aspects of steer-by-wire systems, not otherwise provided for in this maingroup
• CPC Class Codes: B62D 5/006 power actuated
• CPC Class Codes: B62D 5/092 the electric motor being connected to the final driven element of the steering gear, e.g. rack
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

A steering apparatus (10) for a vehicle having steerable road-engaging wheels comprises a rotatable steering wheel (11) and a sensor (12) which senses the rotational position of the steering wheel and generates a first signal corresponding to the sensed rotational position of the steering wheel (11). A first electric motor (14), when energized, resists rotation of the steering wheel (11). A second electric motor (20) is controlled by the signal generated by the sensor for sensing the rotational position of the steering wheel (11). A steering gear (130) is actuated by the second electric motor (20) to turn the steerable wheels of the vehicle. An electrical circuit (19) includes the first and second motors (14 and 20) in series.

Claims

1. A steering apparatus for a vehicle having steerable road-engaging wheels, said apparatus comprising:

a rotatable vehicle steering wheel;

a sensor for sensing the rotational position of said steering wheel and for generating a first signal corresponding to the sensed rotational position of said steering wheel;

a first electric motor for resisting rotation of said steering wheel;

a second electric motor controlled by said first signal;

a steering gear that is actuated by said second electric motor to turn the steerable wheels of the vehicle; and

an electrical circuit that includes said first and second motors in series.

2. A steering apparatus as defined in claim 1 wherein said first and second motors are identical in construction and the magnitude of the current through said first and second motors is substantially the same and the torque produced by said first and second motors is substantially the same.

3. A steering apparatus as defined in claim 1 wherein said steering gear comprises a hydraulic steering gear having a hydraulic valve member that is moved by said second electric motor.

4. A steering apparatus as defined in claim 1 further including a position sensor for sensing the output position of said steering gear, and a control unit responsive to said sensor for sensing rotational position of said steering wheel and for providing a steerable wheel position command depending upon the steering wheel position and the position of the output of the steering gear.

5. A steering apparatus as defined in claim 1 wherein said first and second motors have respective first and second windings which are located in series in said electrical circuit.

6. A steering apparatus as defined in claim 5 further comprising a variable resistor in parallel with said first electric motor.

7. A steering apparatus for a vehicle having at least two steerable road-engaging wheels, said apparatus comprising:

a rotatable vehicle steering wheel;

a sensor for sensing the rotational position of said steering wheel and for generating a first signal corresponding to the sensed rotational position of the steering wheel;

a first electric motor for, when actuated, resisting rotation of said steering wheel;

a second electric motor controlled by said first signal;

a first steering gear actuated by said second electric motor to turn one of said steerable road-engaging wheels;

a third electric motor controlled by said first signal;

a second steering gear actuated by said third electric motor to turn another of said steerable road-engaging wheels; and

an electrical circuit having said second and third electric motors in parallel with each other and in series with said first electric motor.

8. A steering apparatus for a vehicle having steerable road-engaging wheels, said apparatus comprising:

a rotatable vehicle steering wheel;

an electric motor operatively coupled with said steering wheel for resisting rotation of said steering wheel;

an actuatable steering gear for turning the steerable wheels of the vehicle;

an output position sensor operatively coupled to said steering gear for sensing the output position of said steering gear, said output position generating an output signal corresponding to the output position; and

an electric control unit operatively coupled between said electric motor and said output position sensor, said control unit receiving said output signal and energizing said electric motor to resist rotation of said steering wheel based at least partially on said output signal.