ROLL STABILITY CONTROL USING FOUR-WHEEL DRIVE

• US 20060074530A1
• Filed: 10/01/2004
• Published: 04/06/2006
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lu, Jianbo, Mattson, Keith, Brown, Todd, Meyers, Joe, Brewer, Michael
• Granted Patent: US 7,640,081 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 2800/0124 Roll-over conditions
• CPC Class Codes: B60G 2800/0194 transversal with regard to vehicle
• CPC Class Codes: B60G 2800/213 by applying forward/backward torque on each wheel individually
• CPC Class Codes: B60K 23/04 for differential gearing
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60T 2201/14 Electronic locking-differential
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/119 including control of all-wheel-driveline means, e.g. transfer gears or clutches for dividing torque between front and rear axle B60W10/14 takes precedence
• CPC Class Codes: B60W 10/16 Axle differentials, e.g. for dividing torque between left and right wheels
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2720/18 Roll
• CPC Class Codes: B60W 30/04 related to roll-over prevention
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: B60W 40/076 Slope angle of the road

Abstract

A control system (18) and method for controlling an automotive vehicle (10) includes a number of sensors that are used to generate a potential rollover signal. In response to the potential rollover, active differentials (112, 114, 116) may be used alone or in addition to braking to prevent the vehicle from rolling over.

Claims

1. A method of controlling a vehicle with a 4×

4 driving system comprising;

determining a potential rollover condition; and

transferring driving torque through electronically-controlled center differential or electronically-controlled transfer case to front wheels to prevent rollover.

2. A method as recited in claim 1 wherein the step of transferring is performed when a vehicle speed is below a low speed threshold.

3. A method as recited in claim 1 wherein the step of transferring is performed when a steering wheel angle is above a steering wheel angle threshold.

4. A method as recited in claim 1 wherein the step of transferring is performed when a throttle opening is below a throttle opening threshold.

5. A method as recited in claim 1 wherein the step of transferring is performed when a vehicle speed is below a low speed threshold and when a throttle opening is below a throttle opening threshold.

6. A method as recited in claim 1 wherein determining a potential rollover condition is performed in response to a roll rate signal.

7. A method of controlling a vehicle with a 4×

4 driving system comprising;

generating a rollover signal in response to a potential rollover;

increasing a torque in a front wheel through a differential in response to the rollover signal; and

braking a rear outside wheel in response to the rollover signal.

8. A method as recited in claim 7 wherein the step of increasing is performed when a throttle opening is above a throttle opening threshold.

9. A method as recited in claim 7 wherein increasing the torque comprises increasing the torque to a full torque.

10. A method as recited in claim 7 further comprising reducing oversteer yawing in response to increasing the torque and braking.

11. A method as recited in claim 7 further comprising braking a front inside wheel.

12. A method as recited in claim 11 wherein the steps of increasing and braking are performed when a throttle opening is above a throttle opening threshold.

13. A method as recited in claim 7 further comprising determining a wheel lift condition, and wherein braking a front inside wheel is performed during the determination of a wheel lift condition.

14. A method as recited in claim 7 wherein increasing the torque is performed using a limited slip differential or a viscous coupling.

15. A method as recited in claim 7 wherein increasing the torque is performed using a Torsen differential.

16. A method of controlling a vehicle having an active differential comprising:

determining a rollover condition;

in response to the rollover condition, disengaging an inside wheel from an outside wheel with the active differential; and

thereafter, determining a wheel lift condition of an inside wheel.

17. A method as recited in claim 16 further comprising applying engine torque to the outside wheel to prevent rollover.

18. A method as recited in claim 16 wherein determining a wheel lift condition comprises actively determining wheel lift.

19. A method as recited in claim 18 wherein actively determining wheel lift comprises determining wheel lift by applying a change in torque to the inside wheel and monitoring a change in speed of the wheel.

20. A method of controlling a vehicle having a first wheel, a second wheel, and an active differential comprising:

during a potential rollover event or stability control event, determining a slip condition of a first wheel of the vehicle;

reducing torque to the first wheel in response to the slip condition using the active differential; and

increasing torque to the second wheel in response to the slip condition using the active differential.

21. A method as recited in claim 20 wherein reducing torque to the first wheel and increasing torque to the second wheel are performed with an active center differential.

22. A method as recited in claim 20 wherein reducing torque to the first wheel and increasing torque to the second wheel are performed with an active axle differential.

23. A method as recited in claim 20 wherein determining a slip condition comprises determining a slip condition in a traction control system.

27. A method as recited in claim 23 wherein distributing comprises applying positive torque to the outside front wheel.

28. A method as recited in claim 23 wherein distributing comprises reducing understeer by applying positive torque to the outside front wheel.

24. A method of controlling a vehicle having an active differential comprising:

determining a rollover condition;

in response to the rollover condition, disengaging an outside front wheel from an inside wheel with the active differential;

applying a braking torque to the outside front wheel; and

applying powertrain torque to the outside rear wheel to counter a deceleration caused by braking the front outside wheel.

25. A method as recited in claim 24 wherein applying powertrain torque comprises applying powertrain torque to the outside rear wheel to balance a weight transfer from front to rear.

26. A method of controlling a vehicle having an active differential comprising:

determining a rollover condition; and

in response to the rollover condition, using the active differential distributing torque between the front right wheel, front left wheel, rear left wheel and the rear right wheel to prevent rollover.

29. A vehicle having a front wheel comprising:

a differential;

a rollover sensor generating a rollover signal; and

a controller coupled to the rollover sensor and the differential, the controller controlling a differential limiting torque to the front wheels to prevent rollover.

30. A vehicle as recited in claim 29 wherein the differential comprises an active differential.

31. A vehicle as recited in claim 29 wherein the differential comprises an active axle differential.

32. A vehicle as recited in claim 29 wherein the rollover sensor comprises a roll rate sensor.

33. A vehicle as recited in claim 32 wherein the rollover sensor comprises a roll rate sensor and a lateral acceleration sensor.

34. A vehicle as recited in claim 32 wherein the rollover sensor comprises a roll rate sensor, a lateral acceleration sensor and a vehicle speed sensor.

35. A vehicle as recited in claim 32 wherein the rollover sensor comprises roll rate sensor, a lateral acceleration sensor, a vehicle speed sensor, and a yaw rate sensor.