DE10058099A1 - Method and device for detecting or estimating tire wear - Google Patents

Abstract

To detect or estimate tire wear (in 1, 14, 15, 15 '), vehicle dynamics and other parameters influencing tire wear (in 7, 12) are recorded and stored during normal operation of a vehicle, and stored for the approximate detection of the tire condition or Tire wear evaluated. If the wear exceeds a predetermined threshold, an advisory or warning signal (11) is issued. DOLLAR A The method is essentially based on the processing of sensor signals, which are also required for vehicle control systems such as ABS, ESP etc.

Description

The invention relates to a method for recognition or estimating tire wear or tire wear. A device for performing the method is just one if to the invention.

The operational safety of a motor vehicle depends significantly on the condition of the vehicle tires. The rubber layer of the barrel according to the legal regulation, a defined area Do not fall below the value. The wear of the tire tread is determined by the energy converted on the tire and the mate rial properties of the rubber mixture largely determined.

To determine the tire condition, one has so far been on the limited visual assessment of the tire, especially the tire profile or the remaining profile at the weakest Place, the uniformity of wear, etc. for assessment tire.

The present invention is based on the object a reliable process free from subjective influences to identify and estimate the current wear to develop a tire with which a warning Generate signal when a wear threshold is exceeded leaves.  

It turned out that this task with the im Claim 1 defined method in a cost-effective manner can be solved. After that there is something special about the Erfin in the fact that driving during normal vehicle operation dynamic sizes and others affect tire wear transmit measured quantities or estimated quantities and from these Approximate values for tire wear are calculated that the calculated and / or measured, the tire wear reproducing sizes and data stored and for recognition or estimate the tire condition or tire ver wear can be evaluated.

The invention is based on the consideration that the Input variables of motor vehicle control systems, e.g. B. from the wheel sensor signals, taking into account further ones if necessary Measured values that are implemented in the operation of a vehicle on the tire Approximately determine the energy and for evaluation or Estimation of the current tire condition or tire ver wear can be evaluated. It can be used as an additional measurement sizes z. B. the outside temperature and / or the air pressure in the individual tires for wear assessment who the.

A number of particularly advantageous exemplary embodiments of the inventive method are in the accompanying Un Described claims. The invention also relates on appropriate devices for carrying out the procedure proceedings.

Further details, advantages and possible applications The invention can be seen from the attached figures.  

Show it:

Fig. 1 in the form of a chart the most important functional blocks of a device or a program for performing the method according to the invention in accordance with an embodiment of the invention and

Fig. 2 to Fig. 4 in the same representation other Vari anten of the invention.

The charts of Fig. 1 to Fig. 4 illustrate various ways to implement the inventive method. In all cases, the presence of an electronic system is required, which can receive and process electrical sensor signals. The information is expediently processed, stored and evaluated in a microprocessor system. Finally, electrical signals are generated which reflect the wear or tear of the tire and signalize that a wear threshold has been exceeded.

The invention leads to an extension of the functionality an ABS or ESP controller using the existing one Input data and the anyway for the vehicle Control systems require computing processes. Both come Control systems and computing processes in question on the Measurement of wheel rotation behavior based on wheel speed sensors hen, as well as systems in which the tire forces with so-called SWT sensors (side wall torsion sensors) or other suitable force measuring devices recorded and as Input variables of the control system can be evaluated.

There is a message or warning to the driver zeug-Führer even in the event of neglected visual inspection  Tire wear or if the maintenance interval is too long le. The operational safety of the vehicle is determined by the A relation of tire wear to the monitoring mechanism men increased significantly.

According to FIG. 1 (variant 1 ), specifications about vehicle parameters, such as mass etc., are supplied from a symbolically represented source (functional unit 2 ) in a corresponding functional unit 1 for estimating the energy converted on the vehicle tire. "3" symbolizes the specification of Rei fenparameters, such as rolling friction, etc. In addition, in the special example of FIG. 1, the functional unit 1 is supplied with information about the current tire pressure, taking into account the current outside temperature measured with a thermometer 4 is determined; too low tire pressure can e.g. B. with the help of a so-called. DDS measurement method (Deflation Detection System) (function block 5 ), in which all information for tire pressure determination is derived from the turning behavior of the individual vehicle wheels.

The tire pressure (inner tire pressure) is also an input variable of a tire wear map 6 .

In the exemplary embodiment according to FIG. 1, wheel circumferential speeds, which can be determined using conventional wheel sensors, as well as information about the steering wheel angle, the yaw rate and the lateral acceleration of the vehicle are detected and evaluated as driving dynamics variables. The accuracy of the determination of state variables of the transverse dynamics (cornering) can be considerably improved by taking these measured variables into account. Such data are e.g. B. in a conventional ESP system (Electronic Stability Program) as input sizes available anyway.

From the data, which provides a function block 7, the driving state of the vehicle, symbolized by the functional unit is 8, determined; the driving condition in turn allows conclusions to be drawn about the tire slip (lengthways and crossways), symbolized by a block 9 . The tire slip ( 9 ), like the tire pressure ( 5 ) and the predetermined vehicle parameters ( 2 ) and tire parameters ( 3 ), are used to estimate the energy converted on the tire ( 1 ).

With the vehicle parameters stored in the electronic unit 2 ; such as wheelbase, track width, center of gravity, mass, aerodynamic parameters, brake force distribution, drive type etc., as well as with the determined driving condition variables ( 8 ) and tire slip values ( 9 ), the longitudinal and lateral forces are applied using known methods and algorithms (equations of motion of vehicle and wheels) the individual tires are estimated and integrated into energy quantities. Stored information on the kinematics and elastokinematics of the wheel suspensions make it possible to estimate important variables such as toe and camber; their influence is included in the estimation of the lateral forces.

The tire parameters ( 3 ) additionally stored in the electronic unit 6 , such as rolling friction coefficient etc., improve the results.

The determination of low tire pressure using an ambient temperature measurement ( 4 ) and a method (DDS), which is based on the evaluation of wheel circumference speeds and the driving condition, enables the estimation of further energy components that have an impact on tire wear.

From the tire wear maps stored in the electronic unit 6 , which represent material properties, a wear quantity is determined for each tire as a function of the energy implemented on the tire (lengthways and crosswise) and stored in the memory 10 so that the values not get lost even when the vehicle is at rest.

If a predetermined wear threshold is exceeded, an information or warning signal is finally output in a functional unit 11 .

According to variant 2 ( FIG. 2), the circumferential speeds of the wheels are again measured, from which the driving condition (e.g. acceleration, braking, cornering) is determined and the tire slip is estimated. Measuring other sizes like. Steering wheel angle, yaw rate, lateral acceleration improve the accuracy of the determination of state variables of the Querdy namik (cornering).

Also, the tire pressure using a pressure is shown in FIG. 2 sensor 5 a, which may be installed in the tire, measured, and transmitted via an unshown transmitting and receiving means to an evaluation unit 14 in which the power converted at the tire energy is determined. Such pressure measuring devices ( 5 a) are already present in many vehicles, so that there may be no significant additional effort to carry out the method according to the invention.

With the vehicle parameters stored in the electronic unit 2 , such as wheelbase, track width, center of gravity, mass, aerodynamic parameters, braking force distribution, drive type, etc., as well as with the driving condition variables and tire slip values determined in 8, 9, the functional unit 13 uses the known algorithms ( Equations of motion of vehicle and wheels) the longitudinal and lateral forces on the individual tires are estimated and integrated into energy quantities. Stored information on the kinematics and elastokinematics of the wheel suspensions enable the estimation of important variables, such as toe and camber; their influence is included in the estimation of the lateral forces.

In addition, 3 stored tire parameters in the electronic unit, such. B. rolling friction coefficient, improve the results.

According to Fig. 3, a system is used, which in this case is equipped with SWT sensors (functional unit 12 ), which directly detect the longitudinal and transverse forces occurring on the tire. Instead of the SWT sensors, other suitable force measuring devices could also be used. The output signals of the SWT sensors ( 12 ) are fed directly to a corresponding functional unit 15 for estimating the energy converted on the tire.

This type of measurement also improves the accuracy of the determination of state variables of the longitudinal and transverse dynamics. Information ( 13 ) coded on the tire, which is read electronically, enables the selection of the wear maps which best describe the tire; this is indicated in FIG. 3 by the arrow pointing from the functional unit 13 to the unit 6 .

The determination of low tire pressure ( 5 ) with the help of an ambient temperature measurement ( 4 ) and a method (DDS), which is based on the evaluation of wheel circumference speeds and driving condition ( 8 ); enables the estimation of additional energy components that have an impact on tire wear.

Finally, a variant 4 is shown in FIG. 4, according to which the tire parameters read in, encoded on the tire, symbolized by the functional unit 13 , together with tire pressure measured values, which are recorded in a unit 16 , and with tire force measured values, which SWT -Sensors ( 12 ) or other force measuring devices are supplied to a functional unit 15 'for estimating the energy converted on the tire. The further processing of the information until a warning or warning signal ( 11 ) is triggered when the wear threshold exceeds, is carried out in the manner previously described with reference to FIG. 1.

The tire pressure ( 16 ) is also measured and used to estimate further energy components (in 15) that have an impact on tire wear.

From the tire wear maps stored in the electronic unit 6 , a wear variable is determined for each tire as a function of the energies converted on the tire and stored in the memory 10 in the manner described above. Information coded on the tire ( 13 ), which is read electronically, enables the selection of the wear maps ( 6 ) that best describe the tire.

The tire condition or tire wear are also significantly influenced by the age of the tires, at least with relatively little used tires. As is well known, the tire rubber becomes brittle. It may therefore be useful in the wear detection Ver, z. B. in unit 6 or following the processing of the data in unit 6 , include aging component in the calculations, which lead to a corresponding earlier reaching of the wear threshold compared to systems that do not record the tire age; this step of simplicity is not taken into account in the attached figures.

Claims (13)

1.Procedure for recognizing or estimating tire wear or tire wear, characterized in that dynamic vehicle variables and other measured variables and / or estimated variables influencing tire wear are recorded during vehicle operation and these approximate values for tire wear are calculated so that the calculated and / or measured quantities and data reflecting tire wear are stored and evaluated to detect or estimate the tire condition or tire wear. 2. The method according to claim 1, characterized in that the parameters influencing tire wear and / or estimates during vehicle operation constantly or in representative of tire wear Time intervals are recorded and evaluated. 3. The method according to claim 1 or 2, for vehicles with egg electronic vehicle control systems, such as ABS, ESP, chassis control etc., characterized, that as vehicle dynamics parameters from the vehicle Control system determined control input variables, exclusively or together with additional measurands such as outside temperature, tire pressure etc., for recording tire condition or tire wear or tire wear. 4. The method according to one or more of claims 1 to 3, characterized in that as a vehicle dynamic measurement increase the wheel circumference speeds of the individual Vehicle wheels, sizes derived from them, such as acceleration  tendency, coefficient of friction. etc., to determine or estimate tire wear and tear be drawn. 5. The method according to claim 4, characterized in that in addition the steering wheel angle, the yaw rate, the Querbe acceleration of the vehicle, namely a category or several categories of this data, to calculate the Rei window wear can be used. 6. The method according to one or more of claims 1 to 5, characterized in that the driving dynamics Measured variables for calculating or estimating the tire implemented energy are used, from which under Consideration of given vehicle parameters (Mass etc.), taking into account the outside temperature if necessary temperature, tire pressure etc., including Tire wear maps on tire wear is closed. 7. The method according to one or more of claims 1 to 6, characterized in that from the turning behavior of the individual wheels the driving state of the vehicle (Acceleration, deceleration, brake application, curves ride etc.), which indicates the tire slip, determined and to estimate the implemented on the tire Energy (lengthways and crossways) is used. 8. The method according to claim 7, characterized in that the current driving state of the vehicle for determination the tire pressure is evaluated.   9. The method according to one or more of claims 1 to 8, characterized in that the individual Tire forces occurring (longitudinally and transversely) with Help of force measuring devices, e.g. B. with the help of SWT sensors (side-wall torsion sensors), detected and for calculating or estimating the amount implemented on the tire Energy (lengthways and crossways), exclusively or together with additional parameters such as wheel turning behavior, Au outside temperature, etc. 10. The method according to one or more of claims 1 to 9, characterized in that the calculated or ge estimated values of the energy converted on the tire With the help of tire wear maps and evaluated Determination or to estimate the current tire status or tire wear are saved. 11. The method according to one or more of claims 1 to 10, characterized in that a notice or warning signal is output when the memory value of the rei a predetermined wear threshold exceeds. 12. Device for performing the method according to a or more of claims 1 to 11, characterized records that this as an additional device or expanse tion of a conventional motor vehicle control system, such as ABS, ESP, chassis control, etc., is designed and essentially the input variables of the control system tems, which determine the tire wear and tear play back, to estimate the amount of tire transferred Energy records, evaluates and stores.   13. The apparatus according to claim 12, characterized in that this additionally the outside temperature and / or the Tire pressure of the individual vehicle tires recorded and in the calculation or estimation of tire wear refers.