Brake pressure control method for a motor vehicle power brake system

• US 6,460,943 B1
• Filed: 09/27/1994
• Issued: 10/08/2002
• Est. Priority Date: 09/27/1993
• Status: Expired due to Fees

• Current Assignee: Temic Telefunken Microelectronic GmbH (Continental AG), Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Temic Telefunken Microelectronic GmbH (Continental AG), DaimlerChrysler AG (Mercedes-Benz Group AG)
• Inventors: Mueller, Wolfgang, Helldoerfer, Reinhard, Toepfer, Bernhard, Reiner, Michael
• Primary Examiner(s): Lavinder, Jack
• Assistant Examiner(s): KING, BRADLEY T
• Application Number:
  US08/313,983
• Time in Patent Office: 2,933 Days
• Field of Search: 303/3, 303/15, 303/20, 303/155, 303/160, 303/166, 303/167, 303/177, 303/181, 303/113.4
• US Class Current: 303/155
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 8/00 Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force by changing number of effective brake cylinders in power brake systems B60T17/10
• CPC Class Codes: B60T 8/3275 Systems with a braking assistant function, i.e. automatic full braking initiation in dependence of brake pedal velocity

Abstract

A method controls brake pressure for a motor vehicle pressure medium-actuated power brake system in which the adjustment of a proportionality factor (k) between deceleration and brake pressure starting from an initial value (k_o) is limited to a range bounded by a lower limit value and an upper limit value in which range the initial value (k_o) is contained. This produces a warning travel of the pedal when excessive deviation of the brake pressure from the expected value occurs. The warning travel informs the driver of the braking effect which is deviating excessively from the expected degree. Methods are known in which a specific travel (s_p) of the brake pedal is interpreted as a setting of a specific desired deceleration (z_s) of the vehicle and the required brake pressure is set automatically if appropriate by incrementally adjusting a variable proportionality factor (k).

Claims

1. A method for electronically influenceable brake pressure control for a motor vehicle pressure medium-actuated power brake system actuatable via a brake pedal comprising the steps of assigning a specific desired vehicle deceleration within a braking process to each travel of the brake pedal, and selectively setting the required brake pressure automatically by incremental adjustment from an initial value of an intentionally set variable proportionality factor defined by deceleration and brake pressure to constitute a positive real number between a preset lower limit value and a preset upper limit value sized to the brake pressure achievable with the brake system and containing the initial value, wherein a vehicle driver is provided with suitable indication of a braking effect of the vehicle.

2. The method according to claim 1, wherein an interval of equal magnitude from the initial value is provided for the lower limit value and for the upper limit value.

3. The method according to claim 1, wherein the desired vehicle deceleration, a time derivate of the deceleration and actual vehicle speed are determined and evaluated to indicate whether emergency braking is present and the incremental adjustment of the proportionality factor is only limited when emergency braking is not present.

4. The method according to claim 3, wherein an interval of equal magnitude from the initial value is provided for the lower limit value and for the upper limit value.

5. The method according to claim 1, wherein when the upper limit value is reached at the end of an adjustment process of the proportionality factor during a subsequent further brake pedal actuation in order to achieve the desired vehicle deceleration, the proportionality factor is initially returned incrementally from the upper limit value to the initial value and subsequently kept constant.

6. The method according to claim 5, wherein an interval of equal magnitude from the initial value is provided for the lower limit value and for the upper limit value.

7. The method according to claim 6, wherein the desired vehicle deceleration, a time derivate of the deceleration and actual vehicle speed are determined and evaluated to indicate whether emergency braking is present and the incremental adjustment of the proportionality factor is only limited when emergency braking is not present.

8. The method according to claim 2, wherein the interval is a function of one of the initial value, and of the desired vehicle deceleration.

9. The method according to claim 8, wherein the interval is between 0.1·

k_o and 0.3·

k_o.

10. The method according to claim 8, wherein the interval increases linearly with the desired vehicle deceleration.

11. The method according to claim 1, wherein given a deviation of actual deceleration from the desired deceleration of not less than +/−

30%, the initial value for a subsequent braking process is adjusted to a greater extent, and given a deviation of the actual deceleration from the desired deceleration of less than +/−

30% but more than +/−

3%, the initial value is adjusted to a lesser extent, as a function of an adjustment value of the proportionality factor of the instantaneous braking process.

12. The method according to claim 11, wherein an interval of equal magnitude from the initial value is provided for the lower limit value and for the upper limit value.

13. The method according to claim 12, wherein the desired vehicle deceleration, a time derivate of the deceleration and actual vehicle speed are determined and evaluated to indicate whether emergency braking is present and the incremental adjustment of the proportionality factor is only limited when emergency braking is not present.

14. The method according to claim 13, wherein when the upper limit value is reached at the end of an adjustment process of the proportionality factor during a subsequent further brake pedal actuation in order to achieve the desired vehicle deceleration, the proportionality factor is initially returned incrementally from the upper limit value to the initial value and subsequently kept constant.

15. The method according to claim 14, wherein the interval is a function of one of the initial value, and of the desired vehicle deceleration.

16. The method according to claim 1, wherein the present lower limit value k_min is k_o−

dk, and the present upper limit value k_max is k_o+dk, where k_o is the initial value and dk is a prescribed interval.