# US 5,706,198 A · Traction control system with wheel speed correction to compensate for different tire diameters

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- Number: US 5,706,198 A
- Document ID: US5706198A
- Status: Granted
- Kind: A
- Application number: 08/488,243
- Filed: 1995-06-07
- Granted: 1998-01-06
- Earliest claimed: 1994-07-09
- Assignees: Robert Bosch GmbH; Bayerische Motoren Werke Aktiengesellschaft; Mercedes-Benz AG
- Inventors: Johannes Schmitt; Dirk Saewe; Armin Mueller; Alfred Straub
- Web page: https://patentgrep.com/patent/US5706198A

## CPC

- 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)
- B60K 28/16: responsive to, or preventing, spinning or skidding of wheels
- B60T 2240/08: Spare wheel detection; Adjusting brake control in case of spare wheel use
- B60T 2270/206: Monitoring, e.g. parameter monitoring, plausibility check
- B60W 2510/0604: Throttle position
- B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT

## Abstract

In order to avoid faults as a result of different diameters of tires, under prescribed conditions a correction of one wheel speed with respect to the other on each side of the vehicle is performed. The conditions are based on a comparison of the throttle valve angle to the zero torque angle, and a comparison of the speed of the driven wheel to the speed of the non-driven wheel.

## Claims

### Claim 1

Traction control method for a vehicle having driven wheels, non-driven wheels, and an engine generating torque determined by a throttle valve, said method comprising
determining a throttle valve angle DKI,
determining a zero torque angle NMK,
determining the speed VANX of a driven wheel on one side of the vehicle,
determining the speed VNAX of a non-driven wheel on said one side of the vehicle,
comparing DKI to NMK,
comparing VANX to VNAX,
determining that a first pair of conditions is satisfied when DKI.gtoreq.NMK and VANX<VNAX,
determining that a second pair of conditions is satisfied when DKI<NMK and VANX.gtoreq.VNAX,
correcting wheel speeds on said one side of said vehicle to compensate for different tire diameters when one of said first and second pair of conditions is satisfied,
determining drive slip based on said corrected wheel speeds, and
varying wheel speeds until said drive slip falls below a threshold value.

### Claim 2 (depends on 1)

Method as in claim 1 wherein one of said first and second pairs of conditions must be satisfied for a prescribed time before said wheel speeds are corrected.

### Claim 3 (depends on 1)

Method as in claim 1 wherein prescribed conditions must last for a prescribed time before said wheel speeds are corrected, said prescribed conditions comprising at least one of an ABS/TCS being inactive, no rapid changes in engine speed, no rapid changes in wheel speed, vehicle speed above a prescribed speed value, and cornering not detected.

### Claim 4 (depends on 1)

Method as in claim 1 wherein said zero torque angle NMK is determined by measuring engine speed NMOT and calculating NMK according to
NMK=NMOT.sub.-- ST (NMOT-NMOTL)
wherein NMOT.sub.-- ST is a gradient dependent upon configuration of the throttle value and NMOTL is an idling speed.

### Claim 5 (depends on 1)

Method as in claim 1 further comprising filtering said driven wheel speeds VANX prior to comparing with said non-driven wheel speeds VNAX.