Traction control system including individual slip threshold reduction of the drive wheel on the outside of the curve

• US 6,866,349 B2
• Filed: 03/24/2003
• Issued: 03/15/2005
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Sauter, Thomas, Wandel, Helmut
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US10/396,191
• Publication Number:
  US 20030214182A1
• Time in Patent Office: 722 Days
• Field of Search: 303/140, 303/139, 303/189, 303/146, 303/147, 303/148, 303/149
• US Class Current: 303/140
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16

Abstract

A vehicle traction control system having capabilities for braking intervention and coefficient of friction detection is provided, a slipping wheel being braked by braking intervention if a slip threshold is exceeded. In order to improve the lateral stability of the vehicle when cornering on road surfaces having a low coefficient of friction, the slip threshold for the drive wheel on the outside of the curve is reduced independently of that of the drive wheel on the inside of the curve and is set to a lower value than that for the wheel on the inside of the curve.

Claims

1. A traction control system for a vehicle, comprising:

a braking intervention arrangement for providing braking of a slipping drive wheel if a slip threshold for the slipping drive wheel is exceeded; and

an arrangement for adjusting slip thresholds for drive wheels of the vehicle;

wherein when the vehicle is cornering a curve on a road surface having a low coefficient of friction, a slip threshold for a drive wheel on the outside of the curve is independently reduced relative to a slip threshold for a drive wheel on the inside of the curve, and

wherein a pressure build-up gradient for a brake pressure of the drive wheel on the outside of the curve is increased more rapidly than a pressure build-up gradient for a brake pressure of the drive wheel on the inside of the curve.

2. The traction control system as recited in claim 1, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of an adhesive friction value of the road surface.

3. The traction control system as recited in claim 1, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of the vehicle speed.

4. The traction control system as recited in claim 1, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of a radius of the curve.

5. The traction control system as recited in claim 1, wherein the slip threshold for the drive wheel on the outside of the curve is set to a lower value than the slip threshold for the drive wheel on the inside of the curve.

6. The traction control system as recited in claim 1, wherein the pressure build-up gradient for the drive wheel on the outside of the curve is increased as a function of one of an adhesive friction value and the vehicle speed.

7. The traction control system as recited in claim 1, wherein an increased brake pressure is applied to a brake of the drive wheel on the outside of the curve before the drive wheel on the outside of the curve has exceeded the slip threshold for the drive wheel on the outside of the curve.

8. The traction control system as recited in claim 7, wherein a brake pressure between 3 and 9 bar is applied to the brake of the drive wheel on the outside of the curve.

9. The traction control system as recited in claim 1, wherein a pressure reduction gradient for a brake of the drive wheel on the outside of the curve is reduced in comparison to a pressure reduction gradient for a brake of the drive wheel on the inside of the curve.

10. A method for traction control of a vehicle, comprising:

braking a slipping drive wheel by a braking intervention arrangement if a slip threshold for the slipping drive wheel is exceeded;

determining whether the vehicle is cornering a curve on a road surface;

determining a coefficient of friction of the road surface; and

independently reducing a slip threshold for a drive wheel on the outside of the curve to a lower value relative to a slip threshold for a drive wheel on the inside of the curve if it is determined that the vehicle is cornering a curve on a road surface having a low coefficient of friction;

wherein a pressure build-up gradient for a brake pressure of the drive wheel on the outside of the curve is increased more rapidly than a pressure build-up gradient for a brake pressure of the drive wheel on the inside of the curve.

11. The method as recited in claim 10, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of an adhesive friction value.

12. The method as recited in claim 10, wherein the slip threshold for the drive wheel on the outside of the curve is set to a lower value than the slip threshold for the drive wheel on the inside of the curve.

13. The method as recited in claim 10, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of the vehicle speed.

14. The method as recited in claim 10, wherein the slip threshold for the drive wheel on the outside of the curve is reduced as a function of a radius of the curve.

15. The method as recited in claim 10, wherein the pressure build-up gradient for the drive wheel on the outside of the curve is increased as a function of one of an adhesive friction value and the vehicle speed.

16. The method as recited in claim 10, wherein an increased brake pressure is applied to a brake of the drive wheel on the outside of the curve before the drive wheel on the outside of the curve has exceeded the slip threshold for the drive wheel on the outside of the curve.

17. The method as recited in claim 16, wherein a brake pressure between 3 and 9 bar is applied to the brake of the drive wheel on the outside of the curve.

18. The method as recited in claim 10, wherein a pressure reduction gradient for a brake of the drive wheel on the outside of the curve is reduced in comparison to a pressure reduction gradient for a brake of the drive wheel on the inside of the curve.