Process for attenuating the yawing moment in a vehicle with an anti-lock brake system (ABS)

• US 6,044,319 A
• Filed: 05/09/1997
• Issued: 03/28/2000
• Est. Priority Date: 05/14/1996
• Status: Expired due to Term

• Current Assignee: Wabco GmbH (Wabco Holdings Incorporated)
• Original Assignee: Wabco GmbH (Wabco Holdings Incorporated)
• Inventors: Rothen, deceased, Johann, Rosendahl, Hartmut, Koschorek, Ralf
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US08/854,289
• Time in Patent Office: 1,054 Days
• Field of Search: 701/70, 701/71, 701/73, 701/78, 701/80, 701/81, 701/83, 303/146, 303/140, 303/148, 303/149, 303/150, 303/186, 303/188, 303/189
• US Class Current: 701/71
• 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
• 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 8/326 Hydraulic systems
• CPC Class Codes: B60T 8/505 Pressure reapplication in a mu-split situation, i.e. a situation with different coefficients of friction on both sides of the vehicle

Abstract

A process for reducing yaw during braking in a vehicle having an anti-lock braking system (ABS) and traveling on a roadway having different coefficients of friction on opposite sides of the vehicle comprises regulating the braking pressures in the wheels of the vehicle during ABS-controlled braking so that a permissible braking pressure difference (ΔP) between the braking pressures in the high and low wheels is maintained. The permissible braking pressure difference (ΔP) is calculated by an electronic system based on an algorithm that takes into account the frictional value of the road, and/or the load on the vehicle, and/or the wheel base of the vehicle, and/or the wheel gauge of the vehicle, and/or the level of the center-of-gravity of the vehicle. The algorithm increases the value of the permissible braking pressure difference (ΔP) as the frictional value of the road, the load of the vehicle, and the wheel base of the vehicle increase. The algorithm decreases the value of the permissible braking pressure difference (ΔP) as the level of the center-of-gravity of the vehicle and the wheel gauge of the vehicle increase.

Claims

1. A process for reducing yaw during braking in a vehicle traveling on a roadway having different frictional values on opposite sides of said vehicle, said vehicle having a front axle and a rear axle on which wheels are mounted, said vehicle being equipped with an anti-lock braking system which operates to reduce braking pressure in any of said wheels during an ABS-controlled braking, said process comprising:

detecting said braking pressures in said wheels,

calculating a permissible braking pressure difference (Δ

P) between the braking pressure in a high wheel and the braking pressure in a low wheel, said high wheel traveling on a side of the roadway having a higher coefficient of friction than said low wheel, and

adjusting said braking pressures in said high wheel so that said permissible braking pressure difference (Δ

P) is maintained at a constant value,

wherein said permissible braking pressure difference (Δ

P) is calculated in an electronic unit by means of an algorithm which takes into account at least one of the frictional value of the roadway, the load on the vehicle, the wheel base of the vehicle, the wheel gauge of the vehicle, and the level of the center-of-gravity of the vehicle,

wherein said algorithm increases said permissible braking pressure difference (Δ

P) with increases of the frictional value of the roadway, the load on the vehicle, and the wheel base of the vehicle, and decreases said permissible braking pressure difference (Δ

P) with increases in the level of the center-of-gravity of the vehicle and the wheel gauge of the vehicle.

2. The process of claim 1 wherein said frictional value of the roadway is calculated in accordance with the formula:

space="preserve" listing-type="equation">μ

=c×

P.sub.max /F.sub.N

wherein

μ

=the frictional value of the roadway,

c=a constant,

P_max =an ABS deregulating pressure of a wheel on a rear axle of the vehicle, and

F_N =the load of at least one wheel on the rear axle.

3. The process of claim 1 wherein said load of the vehicle is determined by said electronic unit from signals received from an automatic load-dependent brake sensor.

4. The process of claim 1 wherein said load of the vehicle is determined by said electronic unit from signals received from at least one axle load sensor.

5. The process of claim 1 wherein the level of the center-of-gravity of said vehicle is manually entered into said electronic unit.

6. The process of claim 1 wherein the level of the center-of-gravity is determined automatically by said electronic unit.

7. The process of claim 1 wherein the wheel base of the vehicle, the wheel gauge of the vehicle, and the empty weight of the vehicle are manually entered in said electronic unit prior to start-up of the vehicle.