Method of determining an optimized value of brake pressure ratio between a tractor and a trailer or semitrailer

• US 5,409,301 A
• Filed: 11/04/1992
• Issued: 04/25/1995
• Est. Priority Date: 11/07/1991
• Status: Expired due to Term

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Mercedes-Benz AG (Mercedes-Benz Group AG)
• Inventors: Muller, Wolfgang, Klein, Bodo, Topfer, Bernhard
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): Poon, Peter M.
• Application Number:
  US07/971,234
• Time in Patent Office: 902 Days
• Field of Search: 303/7, 303/9.61, 303/9.62, 303/9.69, 303/13, 303/15, 303/20, 303/DIG. 1, 303/DIG. 2, 303/22.1
• US Class Current: 303/7
• CPC Class Codes: B60T 13/66 Electrical control in fluid-pressure brake systems
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations
• CPC Class Codes: B60T 8/1887 especially adapted for tractor-trailer combinations
• CPC Class Codes: B60T 8/323 Systems specially adapted for tractor-trailer combinations
• 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 is provided to determine an optimized value of the brake pressure ratio between a tractor and a trailer or semitrailer. In particular, an increased value of the brake pressure of the trailer or semitrailer in relation to the brake pressure resulting from the position of the brake pedal is supplied for a particular duration at the beginning of a braking operation. The increase of the brake pressure of the trailer or semitrailer takes place as a function of the brake pressure, p_Anh, resulting from the position of the brake pedal. In braking operations when a tractor is travelling without a trailer or semitrailer, an allocation of the achieved deceleration, z_ist, to the brake pressure p_Zug of the tractor is stored as a function of the load state of the tractor. When the tractor is travelling with a trailer or semitrailer, a brake pressure is supplied for the trailer or semitrailer and is allocated to the brake pressure of the tractor such that, in subsequent braking operations, the actual value of the deceleration which is then set at a prevailing brake pressure of the tractor, giving due regard to the load state of the tractor, corresponds to the value, derived from the stored allocation, of the deceleration achieved without a trailer or semitrailer at the same brake pressure of the tractor.

Claims

1. A method of determining an optimized value of brake pressure ratio between a tractor and one of a trailer and semitrailer, comprising selectively increasing a variable initial targeted brake pressure of one of the trailer and the semitrailer in relation to a trailer or semitrailer brake pressure resulting from a brake pedal position for a particular duration only at initiation of a braking operation, wherein the increase of the brake pressure of one of the trailer and semitrailer is a variable increase as a function of the trailer or semitrailer brake pressure resulting from the brake pedal position.

2. The method according to claim 1, wherein the increase of the brake pressure of one of the trailer and semitrailer only takes place fully if the intensity of the braking operation is below predetermined threshold values of at least one of brake pedal actuation speed and a deceleration set value.

3. The method according to claim 1, wherein the increase of the brake pressure of one of the trailer and semitrailer is ended when one of an actual value of the deceleration has reached a predetermined fraction of its set value and a predetermined time span has elapsed since the beginning of the braking operation.

4. The method according to claim 3, wherein the increase of the brake pressure of one of the trailer and semitrailer only takes place fully if the intensity of the braking operation is below predetermined threshold values of at least one of brake pedal actuation speed and a deceleration set value.

5. The method according to claim 1, wherein the size of the increase of the brake pressure of one of the trailer and semitrailer varies with travelling speed of a tractor-trailer unit prior to the beginning of the braking operation.

6. The method according to claim 5, wherein the increase of the brake pressure of one of the trailer and semitrailer only takes place fully if the intensity of the braking operation is below predetermined threshold values of at least one of brake pedal actuation speed and a deceleration set value.

7. The method according to claim 5, wherein the increase of the brake pressure of one of the trailer and semitrailer is ended when one of an actual value of the deceleration has reached a predetermined fraction of its set value and a predetermined time span has elapsed since the beginning of the braking operation.

8. The method according to claim 1, wherein the size of the increase of the brake pressure of one of the trailer and semitrailer varies with at least one of a set value of deceleration and brake pedal actuation speed.

9. The method according to claim 8, wherein the increase of the brake pressure of one of the trailer and semitrailer only takes place fully if the intensity of the braking operation is below predetermined threshold values of at least one of brake pedal actuation speed and a deceleration set value.

10. The method according to claim 8, wherein the increase of the brake pressure of one of the trailer and semitrailer is ended when one of an actual value of the deceleration has reached a predetermined fraction of its set value and a predetermined time span has elapsed since the beginning of the braking operation.

11. The method according to claim 8, wherein the size of the increase of the brake pressure of one of the trailer and semitrailer varies with travelling speed of a tractor-trailer unit prior to the beginning of the braking operation.