Brake control system

• US 6,325,469 B1
• Filed: 09/07/1999
• Issued: 12/04/2001
• Est. Priority Date: 09/06/1996
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated), General Motors Corporation (General Motors Company)
• Inventors: Ghoneim, Youssef A, Lin, William C, Carson, Douglass L, Bassett, Duane E, Turski, Michael P, Lee, Alan J, Hu, Hong X, Chen, Hsien H, Chin, Yuen-Kwok, Paul, Ronald, Pastor, Stephen R, Rizzo, Michael D
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): SICONOLFI, ROBERT
• Application Number:
  US09/230,816
• Time in Patent Office: 819 Days
• Field of Search: 303/139, 303/140, 303/146, 303/147, 303/148
• US Class Current: 303/140
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02

Abstract

A brake system control for use in a vehicle with four wheels comprising the steps of: determining a desired yaw rate (454); determining a yaw torque command responsive to the desired yaw rate (806); if the vehicle is in an anti-lock braking mode during driver commanded braking, applying the yaw torque command to only one of the four wheels to release brake pressure in said one of the four wheels (258-266, 274, 278, 280, 410-418); if the vehicle is in a positive acceleration traction control mode during driver commanded acceleration, applying the yaw torque command to only one of the four wheels to apply brake pressure in said one of the four wheels (258-266, 288-292, 410-418); and if the vehicle is not in the anti-lock braking mode or in the positive acceleration traction control mode, then: (i) determining whether a vehicle brake pedal is depressed (370); (ii) if the vehicle brake pedal is depressed, applying brake force to the vehicle wheels responsive to the depression of the brake pedal (374, 412, 418), wherein the applied brake force is modified to at least two of the vehicle wheels to create a left-right brake torque differential responsive to the yaw torque command.

Claims

1. A brake system control method for use in a vehicle with four wheels comprising the steps of:

determining a desired yaw rate;

determining a yaw torque command responsive to the desired yaw rate, wherein the yaw torque command is determined in understeer conditions and is determined in oversteer conditions;

if the vehicle is in an anti-lock braking mode during driver commanded braking, applying the yaw torque command to only one of the four wheels to release brake pressure in said one of the four wheels;

if the vehicle is in a positive acceleration traction control mode during driver commanded acceleration, applying the yaw torque command to only one of the four wheels to apply brake pressure in said one of the four wheels; and

if the vehicle is not in the anti-lock braking mode or in the positive acceleration traction control mode, then;

(i) determining whether a vehicle brake pedal is depressed;

(ii) if the vehicle brake pedal is depressed, applying brake force to the vehicle wheels responsive to the depression of the brake pedal, wherein the applied brake force is modified to at least two of the vehicle wheels to create a left-right brake torque differential responsive to the yaw torque command.

2. A brake system control method according to claim 1, wherein the applied brake force is modified by releasing brake pressure in one of said two wheels and applying brake pressure in the other of said two wheels.

3. A brake system control method according to claim 1, wherein the brake force applied to the vehicle wheels is modified by

determining a brake command responsive to the depression of the brake pedal (374),

reducing the brake command to one of the at least two wheels in response to the yaw torque command (412), and

increasing the brake command to the other of the at least two wheels in response to the yaw torque command (418).

4. A brake system control method according to claim 1, wherein in the traction control mode a difference between a driven wheel speed and a vehicle speed is controlled to a target value, the control method also comprising the step of:

responsive to the desired yaw rate, adaptively adjusting the target value within a predetermined range (1224), wherein a difference between an actual yaw rate and the desired yaw rate is minimized when the positive acceleration traction control is activated.

5. A brake system control method according to claim 1, also comprising the steps of:

determining responsive to the desired vehicle yaw rate whether the vehicle is in a state of oversteer (602); and

if the vehicle is in a state of oversteer and if the vehicle is in the anti-lock braking mode, reducing an average brake force applied to the rear brakes by the anti-lock brake control to reduce a difference between the desired vehicle yaw rate and an actual vehicle yaw rate (152, 1218).

6. A brake system control method according to claim 1, also comprising the step of:

responsive to the desired yaw rate, reducing an average brake force applied to at least two of the wheel brakes to reduce a difference between the desired vehicle yaw rate and the actual vehicle yaw rate (152, 1218).