Electronic rear brake proportioning system

• US 6,357,836 B1
• Filed: 08/30/1999
• Issued: 03/19/2002
• Est. Priority Date: 03/04/1997
• Status: Expired due to Fees

• Current Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Schmitt, Hubert E., Dehn, Anton
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US09/385,332
• Time in Patent Office: 932 Days
• Field of Search: 303/113.5, 303/186
• US Class Current: 303/113.5
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
• CPC Class Codes: B60T 8/266 using valves or actuators with external control means B60T8/261 takes precedence

Abstract

A rear brake proportioning system for a vehicle which is enabled upon the rear wheel speed exceeding a wheel speed threshold and activated upon rear wheel slip exceeding a slip threshold.

Claims

1. An electronic rear brake proportioning system for a vehicle having at least one front wheel brake and one rear wheel brake, the wheel brakes being coupled to and actuated by a master cylinder, the electronic rear brake proportioning system comprising:

a normally open solenoid valve connected between the master cylinder and the rear wheel brake; and

a controller electrically connected to said solenoid valve, said controller being enabled when a first vehicle operating parameter exceeds a first threshold and said controller being operable to close said solenoid valve to isolate the rear wheel brake from the master cylinder when a second vehicle operating parameter exceeds a second threshold while said first operating parameter continues to exceed said first threshold.

2. A rear brake proportioning system according to claim 1 further including a speed sensor for monitoring a speed of the wheel associated with the rear wheel brake, said speed sensor generating a rear wheel speed signal, and wherein said first vehicle operating parameter is said rear wheel speed and said first threshold is a predetermined rear wheel speed, said controller being enabled when the rear wheel speed exceeds said predetermined rear wheel speed.

3. A rear brake proportioning system according to claim 2 wherein said controller is operative to calculate a rear wheel slip, and further wherein said second vehicle operating parameter is said rear wheel slip and said second threshold includes a predetermined value of rear wheel slip, said controller closing said solenoid valve upon being enabled and said rear wheel slip exceeding said rear wheel slip threshold.

4. A rear brake proportioning system according to claim 3 wherein said controller is operative to calculate a deceleration of the controlled rear wheel and further wherein said second threshold also includes a road surface factor which is a function of said rear wheel deceleration, said second threshold being a combination of said road surface factor and said predetermined value of rear wheel slip.

5. A rear brake proportioning system according to claim 4 wherein said controller is operative to calculate a deceleration factor which is a function of elapsed braking time and further wherein said second threshold also includes said deceleration factor, said deceleration factor being combined with said road surface factor and said predetermined value of rear wheel slip.

6. A rear brake proportioning system according to claim 3 wherein said controller is operative to calculate a deceleration of the controlled rear wheel and further wherein said second threshold also includes a deceleration factor which is a function of elapsed braking time, said second threshold being a combination of said road deceleration factor and said predetermined value of rear wheel slip.

7. A rear brake proportioning system according to claim 6 wherein said controller is operative to calculate a road surface factor which is a function of rear wheel deceleration and further wherein said second threshold also includes said road surface factor, said road surface factor being combined with said deceleration factor and said predetermined value of rear wheel slip.

8. A rear brake proportioning system according to claim 3 further including a front wheel speed sensor for monitoring the speed of the wheel associated with the front wheel brake, said controller being responsive to said front wheel speed to activate said solenoid valve.

9. A rear brake proportioning system according to claim 3 wherein said controller is further operable to selectively and intermittently reopen said solenoid valve to increase the pressure applied to said controlled rear wheel brake.

10. A rear brake proportioning system according to claim 3 said controller is operative to maintain said isolation of the rear wheel brake for a predetermined time period after the vehicle has stopped.

11. An electronic rear brake proportioning system according to claim 10 wherein said predetermined time period is a first predetermined time period and further wherein said controller is responsive to a vehicle brake pedal being released to open said solenoid valve after a second predetermined time period has elapsed, said second time period being shorter than said first time period.

12. A rear brake proportioning system according to claim 3 wherein said controller is operative to open said solenoid valve upon the elapse of a predetermined time period following said rear wheel slip falling below said rear wheel slip threshold.

13. A rear brake proportioning system according to claim 3 wherein said controller is operative to open said solenoid valve upon the elapse of a predetermined time period following said rear wheel speed exceeding a predetermined rear-wheel speed recovery threshold.

14. A rear brake proportioning system according to claim 3 wherein the rear brake proportioning system is included in an anti-lock brake system.

15. A rear brake proportioning system according to claim 3 wherein the rear brake proportioning system is included in a traction control system.

16. An electronic rear brake proportioning system for a vehicle having at least one front wheel brake and one rear wheel brake, the wheel brakes being actuated by a master cylinder, the electronic rear brake proportioning system comprising:

a normally open solenoid valve connected between the master cylinder and the rear wheel brake;

a speed sensor for monitoring the speed of the wheel associated with the rear wheel brake, said speed sensor generating a rear wheel speed signal; and

a controller electrically connected to said speed sensor and said solenoid valve, said controller being responsive to only said rear wheel speed signal during a braking cycle to close said solenoid valve to isolate said rear wheel brake from said master cylinder and maintain said isolation for a first predetermined time period after the vehicle has stopped.

17. An electronic rear brake proportioning system according to claim 16 wherein said predetermined time period is a first predetermined time period and further wherein said controller is responsive to a vehicle brake pedal being released to open said solenoid valve after a second predetermined time period has elapsed, said second time period being shorter than said first time period.

18. An electronic rear brake proportioning system for a vehicle having at least one front wheel brake and one rear wheel brake, the wheel brakes being actuated by a master cylinder, the electronic rear brake proportioning system comprising:

a normally open solenoid valve connected between the master cylinder and the rear wheel brake;

a speed sensor for monitoring the speed of the wheel associated with the rear wheel brake, said speed sensor generating a rear wheel speed signal; and

a controller electrically connected to said speed sensor and said solenoid valve, said controller being responsive to only said rear wheel speed signal during a braking cycle to close said solenoid valve to isolate said rear wheel brake from said master cylinder, said controller further being operative to open said solenoid valve upon the elapse of a predetermined time period following said rear wheel speed exceeding a predetermined rear wheel speed recovery threshold.