Method and apparatus for adapting motor vehicle drive slip threshold values for a drive slip and/or a brake slip control system to tires

• US 5,357,434 A
• Filed: 01/27/1992
• Issued: 10/18/1994
• Est. Priority Date: 01/26/1991
• Status: Expired due to Term

• Current Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Original Assignee: Mercedes-Benz AG (Mercedes-Benz Group AG)
• Inventors: Muller, Armin, Zimmer, Richard, Freitag, Rainer
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): PARK, COLLIN
• Application Number:
  US07/826,948
• Time in Patent Office: 995 Days
• Field of Search: 364/426.01, 364/426.02, 364/426.03, 180/197, 303/91, 303/94, 303/95, 303/100, 303/102, 303/103, 303/109
• US Class Current: 701/75
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60T 2240/08 Spare wheel detection; Adjusting brake control in case of spare wheel use
• CPC Class Codes: B60T 2270/208 adapted to friction condition
• CPC Class Codes: B60T 2270/211 Setting or adjusting start-control threshold
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60W 2710/0605 Throttle position

Abstract

An apparatus and method adapts response slip threshold values for a drive slip and/or a brake slip control system to the tires fitted to a motor vehicle. The drive torque provided at the driven vehicle wheels is determined from measured operating data such as fuel supply and/or combustion air supply, engine speed and total transmission ratio of the drive train of the vehicle. From this determination, the adhesion coefficient μ_a utilized is determined with a predetermined or measured axle load at the driven vehicle wheels. From the correlation of these adhesion coefficients μ_a with measured values of the drive slip λ_a, the μ slip characteristic of the tires is determined and, corresponding thereto, the response slip thresholds λ_A and λ_B for the drive slip and the antiblocking control are set. A sliding averaging over the quotient μ_a /λ_a of continuously determined μa, λ_a value pairs is utilized for recognizing the tire characteristic of summer/winter tires.

Claims

1. A method for adapting slip threshold values for a drive slip control system and a brake slip control system to tires fitted to a motor vehicle, comprising the steps of (a) determining, during a dynamically stable state of motion of the vehicle in which straight-ahead travel and equality of speed of driven vehicle wheels occur, an adhesion coefficient, μ

, utilized between a roadway and driven vehicle wheels of the motor vehicle from dynamic data of the vehicle comprising speed of the vehicle and drive slip of the driven vehicle wheels detected by wheel speed sensors individually allocated to the respective driven and to non-driven vehicle wheels of the motor vehicle, (b) deducing from the correlation between the utilized adhesion coefficient, μ

, and the measured drive slip, a μ

slip characteristic of the tires, and (c) changing, if a slip requirement of the tires which is required for transfer of a defined torque differs from a value characteristic of a standard type of the tires, response thresholds for the drive slip control and the brake slip control system wherein the step of determining the adhesion coefficient includes (a'"'"') determining drive torque provided at the driven vehicle wheels from measured supply parameters of a combustion engine of the motor vehicle, engine speed and total transmission ratio of the drive train, (a") utilizing one of predetermined and measured normal force representative of axle load, LHA, at the driven vehicle wheels in accordance with the relationship μ

_a =F_z /L_HA, in which F_z designates applicable traction force of the drive train of the motor vehicle as defined by the relationship F_z =M_z /r_dyn in which r_dyn is the dynamic rolling radius of the driven vehicle wheels and Mz is the propulsive torque of the drive train applied via the roadway, and (a'"'"'") determining from the correlation of the adhesion coefficient with the measured drive slip, the μ

slip characteristic of the tires and (a"") setting the response slip thresholds for the drive slip and the antiblocking control corresponding to the determined μ

slip characteristic of the tires.

2. The method according to claim 1, wherein the device torque of the motor vehicle is determined from mass delivery rate of combustion air supplied to the combustion chambers of the engine.

3. The method according to claim 1, wherein the drive torque is determined from fuel quantity supplied to the engine of the motor vehicle.

4. The method according to claim 3, wherein the drive torque of the engine is determined from mass delivery rate of combustion air supplied to the combustion chambers of the engine.

5. A device for carrying out the method for adapting slip threshold values for a drive slip control system and a brake slip control system for a road vehicle, comprising (a) an electronic control unit configured to generate from processing output signals of wheel speed sensors representative of at least one of level and frequency of the wheel speeds of the driven and the non-driven vehicle wheels, required drive signals for the drive slip control system and the brake slip control system such that, in the case of a drive slip control, a vehicle wheel tending to spin is decelerated again by actuating its associated wheel brake and, if such braking is insufficient to reduce the drive slip below a threshold value, the engine torque is reduced and, in the case of brake slip control, the braking forces are reduced when a threshold value of at least one of brake slip and the wheel decelerations is exceeded, and (b) an additional electronic processing unit inputted with rotational speed of the vehicle engine, at least one of mass delivery rate of combustion air quantity supplied to the engine and fuel quantity supplied to the engine, wheel speeds of the driven and of the non-driven vehicle wheels, and axle load, LHA, at the driven vehicle wheels, to determine the adhesion coefficient instantaneously utilized in driving operation, from the relationship

View Dependent Claims (6, 7, 8)

6. The device according to claim 5, wherein a temperature-sensitive air mass flow measuring device is provided for detecting the mass delivery rate of the combustion air.

7. The device according to claim 5, wherein an axle load measuring device responding to spring deflection of the vehicle suspension is configured to generate electrical output signals representing axle load.

8. The device according to claim 7, wherein a temperature-sensitive air mass flow measuring device is provided for detecting the mass delivery rate of the combustion air.