Method for controlling brake force distribution

• US 6,322,169 B1
• Filed: 07/14/2000
• Issued: 11/27/2001
• Est. Priority Date: 11/20/1997
• Status: Expired due to Fees

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Fennel, Helmut
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US09/554,648
• Time in Patent Office: 501 Days
• Field of Search: 303/186, 303/113.5, 303/187, 303/188, 303/199, 303/183, 303/176, 303/166, 303/155, 303/9.62, 303/9.75, 188/349, 188/181.C, 188/188.A, 701/70, 701/71, 701/78, 701/82, 701/83
• US Class Current: 303/186
• CPC Class Codes: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle

Abstract

To govern or control the distribution of brake force, first a switch-over to maintaining the brake force or the braking pressure on the rear wheels constant will be performed upon the commencement and/or detection of a braking operation. From the initial vehicle deceleration upon commencement of the braking operation, a vehicle reference quantity is derived by measuring the rotational behavior of the rear wheels, by filtering the measured values and by extrapolation, whereupon the current rotational behavior of the rear wheels is compared with this reference quantity. Preferably, three cases are distinguished in the analysis of the rotational behavior of the rear wheels and thereafter, depending on the result of the analysis, the braking pressure is kept constant or braking pressure increase in the rear-wheel brakes is allowed.

Claims

1. Method of governing or controlling a distribution of brake force to front and rear wheels of an automotive vehicle, wherein a brake force or the braking pressure in the rear wheels is governed or controlled depending on a wheel rotational behavior, the method comprising the steps of:

a) detecting a commencement of a braking operation or a brake actuation process,

b) introducing a delay period,

c) maintaining the brake force or the braking pressure on the rear wheels constant at a first level,

d) deriving a reference quantity by measuring, filtering and extrapolating values derived from a rotational behavior of the rear wheels,

d) comparing a current rotational behavior of a rear wheel with the reference quantity, and

e) evaluating the comparison of the current rotational behavior of the rear wheel with the reference quantity to control one of the brake force distribution and anti-lock control of the rear wheels.

2. Method as claimed in claim 1, wherein the commencement of the braking operation or the brake actuation process is detected by evaluating a brake light switch signal.

3. Method as claimed in claim 1, wherein the delay period is in the range of 5 msec to 30 msec.

4. Method as claimed in claim 1, wherein the reference quantity is determined during a measurement period.

5. Method as claimed in claim 4, wherein the measurement period is in the range of 50 msec to 500 msec.

6. Method as claimed in claim 1, wherein the rotational behavior of the rear wheels is determined by means of a differential sensor.

7. Method as claimed in claim 6, wherein the rotational behavior of the rear wheels is measured by means of a rotational speed sensor on each individual rear wheel.

8. Method as claimed in claim 1, wherein the braking pressure in the rear wheels is maintained generally constant until the braking operation is terminated when, after detection of the brake actuation process and determination of the reference quantity, the wheel deceleration or the difference between the current speed of the rear wheel and the reference quantity remain constant or increase to a relatively small extent.

9. Method as claimed in claim 1, further including the step of maintaining the brake force on the rear wheels at a second level, wherein said second level represents a greater brake pressure than said first level, and wherein said second level is allowed when the current wheel deceleration decreases or when the current wheel speed approaches the reference quantity.

10. Method as claimed in claim 9, wherein said current wheel speed is calculated as the average value between the speeds of both rear wheels.

11. Method as claimed in claim 1, wherein a variation in braking pressure in the rear wheels is approximated by acquiring and evaluating one of pressure control signals, pressure adjusting signals, and the rotational behavior of the rear wheels and by producing a pressure model.

12. Method of governing or controlling a distribution of brake force to a vehicle having front wheels, rear wheels, brakes associated with the front wheels and the rear wheels, and a brake system with adjustment of the brake force distribution to the brakes associated with the rear wheels, a brake force or a braking pressure in the rear wheels being controlled depending on a wheel rotational behavior, the method comprising the steps of:

a) detecting a commencement of a braking operation or a brake actuation process,

b) introducing a delay period or a waiting period,

c) maintaining the brake force or the braking pressure on the rear wheels constant at a first level after expiry of the delay period or the waiting period,

d) measuring a wheel speed of one or more rear wheels during a measurement period,

e) deriving a reference quantity for the braking operation or the brake actuation process,

g) comparing one of a current wheel speed and a current vehicle deceleration to the reference quantity, and

g) controlling the brake force distribution of the rear wheels based on the comparison step.

13. Method as claimed in claim 12, wherein the reference quantity is derived from an initial vehicle deceleration during the measurement period.

14. Method as claimed in claim 13, wherein the initial vehicle deceleration is derived by measuring a wheel speed of only one rear wheel.

15. Method as claimed in claim 12, wherein the wheel speed is measured by means of a differential wheel sensor.

16. Method as claimed in claim 12, wherein the wheel speed is measured by means of an individual wheel sensor.

17. Method as claimed in claim 12, wherein the commencement of the braking operation or the brake actuation process is detected by evaluating a brake light switch signal.

18. Method as claimed in claim 12, wherein the delay period is in the range of 5 msec to 30 msec.

19. Method as claimed in claim 12, wherein the measurement period is in the range of 50 msec to 500 msec.

20. Method as claimed in claim 12, wherein the braking pressure in the rear wheels is maintained generally constant until the braking operation is terminated when, after detection of the brake actuation process and determination of the reference quantity, the wheel deceleration or the difference between the current wheel speed of the one or more rear wheels and the reference quantity remain constant or increase to a relatively small extent.

21. Method as claimed in claim 12, further including the step of maintaining the brake force on the rear wheels at a second level, wherein said second level represents a greater brake pressure than said first level, and wherein said second level is allowed when the current wheel deceleration decreases or when the current wheel speed approaches the reference quantity.

22. Method as claimed in claim 12, wherein the current wheel speed is calculated as the average value between the speeds of both rear wheels.