Power-assisted steering system and method with compensation of pull induced by tire pressure loss

• US 6,250,421 B1
• Filed: 03/21/2000
• Issued: 06/26/2001
• Est. Priority Date: 03/21/2000
• Status: Expired due to Term

• Current Assignee: TRW Inc. (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: Poshadlo, Michael Lawrence
• Primary Examiner(s): Hurley, Kevin
• Application Number:
  US09/531,655
• Time in Patent Office: 462 Days
• Field of Search: 180/402, 180/403, 180/417, 180/421, 180/422, 180/423, 180/443, 180/445, 180/446, 701/41, 701/42, 701/43, 701/44, 340/442, 340/445, 340/446, 340/447, 340/448
• US Class Current: 180/446
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B62D 5/0472 for damping vibrations

Abstract

A power-assisted steering system (10) for a vehicle that has steerable front wheels (26 and 28) that are inflated. The system (10) includes a manually operated steering member (12) for steering input from a vehicle operator. A series of components (14-22) relays forces between the steering member (12) and the steerable front wheels (26 and 28). A motor (32) provides an assist steer force to steer the steerable wheels (26 and 28) in response to a force applied to the steering member (12). At least one tire pressure sensor (e.g., 66) monitors an inflation pressure of one of the front wheels (e.g., 26). A controller (42) determines and accordingly controls a compensating steer force to the steerable wheels (26 and 28), responsive to the monitored inflation pressure, which attenuates force transmitted to the steering member (12) due to front wheel inflation condition.

Claims

1. A power-assisted steering system for a vehicle having steerable front wheels that are inflated, said system comprising:

a manually operated steering member for steering input from a vehicle operator;

means for relaying forces between said steering member and the steerable front wheels;

means for providing an assist steer force to steer the steerable wheels in response to a force applied to said steering member;

means for monitoring an inflation pressure of one of the front wheels; and

means for providing a compensating steer force to the steerable wheels, responsive to the monitored inflation pressure, that attenuates force transmitted to said steering member due to front wheel inflation condition.

2. A system as set forth in claim 1, wherein said means for providing an assist steer force includes an electric assist motor.

3. A system as set forth in claim 2, wherein said means for providing a compensating steer force includes means for modifying force provided by said electric assist motor.

4. A system as set forth in claim 1, includes means for monitoring inflation pressure of a plurality of wheels, said means for monitoring an inflation pressure of one of the front wheels being included within said means for monitoring inflation pressure of a plurality of wheels, and said means for providing a compensating steer force includes means, responsive to the monitored inflation pressure of the plurality of wheels, that attenuates force transmitted to said steering member due to front wheel inflation condition.

5. A system as set forth in claim 1, including means for providing a notification to a vehicle operator of the occurrence of an attenuation of force transmitted to said steering member due to front wheel inflation condition.

6. A method of controlling a power-assisted steering system for a vehicle having steerable front wheels that are inflated, said method comprising:

relaying forces between a manually operated steering member and steerable front wheels;

providing an assist steer force to steer the steerable wheels in response to a force applied to the steering member;

monitoring an inflation pressure of one of the front wheels; and

providing a compensating steer force to the steerable wheels, responsive to the monitored inflation pressure, that attenuates force transmitted to the steering member due to front wheel inflation condition.

7. A method as set forth in claim 6, wherein said step of providing an assist steer force includes the assist steer force by an electric assist motor.

8. A method as set forth in claim 7, wherein said step of providing a compensating steer force includes modifying force provided by the electric assist motor.

9. A method as set forth in claim 6, including monitoring inflation pressure of a plurality of wheels, said step of monitoring an inflation pressure of one of the front wheels being included within said step of monitoring inflation pressure of a plurality of wheels, and said step of providing a compensating steer force includes attenuating force transmitted to the steering member due to front wheel inflation condition derived from the monitored inflation pressure of the plurality of wheels.

10. A method as set forth in claim 6, including providing a notification to a vehicle operator of the occurrence of an attenuation of force transmitted to the steering member due to front wheel inflation condition.