DE102012023021A1 - Method of determining tire tread value within driving operation of motor vehicle, involves repeatedly detecting steering angle of motor vehicle, where each steering angle is assigned to travel curve parameter - Google Patents

Abstract

The method involves repeatedly detecting a steering angle of the motor vehicle, where each steering angle is assigned to a travel curve parameter. The rotational speed for the travel curve parameters is determined by sensor units (4,5), which are assigned to a wheel having a profiled tire. A predetermined number of rotational speeds are stored as function of the travel curve parameters. The tire profile values (6) opposing tires are calculated depending on the travel curve parameters and the rotational speeds. The profile values are outputted. Independent claims are included for the following: (1) a motor vehicle with a control unit, (2) a computer program for executing the tire tread value determining method; and (3) a computer program product comprising program code unit stored in a computer readable data carrier.

Description

The invention relates to a method for determining a tire tread value within a driving operation of a motor vehicle.

Methods for monitoring individual components are increasingly used in motor vehicles to ensure, for example, the driving behavior of a motor vehicle over a long period of operation.

From the general state of the art, methods are known for controlling a tire pressure, for monitoring a wear of brake systems or the like, which support a safe use of the motor vehicle. These methods usually generate a warning signal should wear occur or pressure loss become detectable.

In addition to the statutory provisions relating to the minimum tread depth of a tire, it is known that the condition of a tire also has an effect on the driving behavior of a motor vehicle since, for example, too worn tires have less adhesion in certain situations.

From the DE 10 2007 029 870 A1 there is disclosed a tire condition monitoring method and apparatus. The tire pressure in the individual wheels is monitored by means of a speed difference of the individual wheels. For this purpose, at least one analysis value is formed from wheel speed signals of the vehicle wheels, from which reference is made to a tire condition. The analysis value is, for example, an absolute rolling circumference of a tire, which is determined by an evaluation of wheel speed signals and signals from at least one sensor for measuring the speed of the vehicle above the ground. From the analysis value is concluded on a pressure drop or a load or load of the tire.

An object underlying the invention is to further improve the driving safety by means of a method for detecting a tire tread value in a motor vehicle, wherein the method can be carried out without having to provide additional components.

This object is solved by the features of patent claim 1. Further advantageous embodiments of the invention are each the subject of the dependent claims. These can be combined in a technologically meaningful way. The description, in particular in conjunction with the drawing, additionally characterizes and specifies the invention.

• – Wiederholtes Erfassen eines Lenkeinschlags des Kraftfahrzeugs, wobei jedem Lenkeinschlag ein Fahrkurvenparameter zugeordnet wird,
• – Bestimmen von Umdrehungszahlen für jeden Fahrkurvenparameter mittels Sensormittel, die jeweils einem einen profilierten Reifen aufweisendem Rad zugeordnet sind,
• – Speichern einer vorgegebenen Anzahl der Umdrehungszahlen als Funktion der Fahrkurvenparameter,
• – Berechnen von Profilwerten jeweils gegenüberliegender Reifen in Abhängigkeit der Fahrkurvenparameter und der Umdrehungszahlen, und
• – Ausgeben der Profilwerte.

Accordingly, a method for determining a tire tread value within a driving operation of a motor vehicle is provided, comprising the following steps:

• - Repeated detection of a steering angle of the motor vehicle, each steering angle is assigned a Fahrkurvenparameter,
• Determining revolution numbers for each travel-path parameter by means of sensor means each associated with a wheel having a profiled tire,
• Storing a predetermined number of revolution numbers as a function of the travel curve parameters,
• Calculating profile values of respectively opposite tires as a function of the travel curve parameters and the rotational speeds, and
• - Output of the profile values.

Accordingly, in a first step, initially a sufficiently high number of travel curve parameters are determined, which are derived from the steering angle. When driving this means that the motor vehicle passes through a plurality of different curved curves, with each steering angle, for example, the radius derived therefrom is assigned as Fahrkurvenparameter. Together with the driving curve parameters, revolution numbers of the respective wheel are determined for each wheel of the motor vehicle by means of sensors. Both values, that is to say the driving curve parameters and the rotational speeds of the respective wheel, are stored and recorded over a certain period of time, until finally a predefined number of rotational speeds is stored as a function of the driving curve parameters. By comparing opposing wheels, a profile value for each tire can now be determined by considering the difference in the number of revolutions. Accordingly, it is possible to detect a worn tire or to prove a tire change on single or all wheels. This information can be further processed, for example, in an on-board computer. In one embodiment of the method, the trajectory parameters are formed by combining the steering angles at multiple intervals, the intervals including equal ranges of steering angles, different ranges of steering angles, overlaps of steering angles, or omissions of steering angles.

Different steering angles can thus be summarized at intervals. Thus, a division into a few groups can be made, for example, the first group represents low curve radii, the second group mean curve radii and the third group extreme curve radii. The assignment can be made based on the steering angle, with the Make intervals in different ways. Thus, the intervals may include equal ranges of steering angles, different ranges of steering angles, overlaps of steering angles, or omissions of steering angles. The preferred assignment of the steering angles to intervals can be based on experimental results, but also be made dependent on the preferred application of the motor vehicle.

In a further embodiment of the method, the travel curve parameters include a straight-ahead travel.

In this embodiment, in addition to or in addition to the above assignment of the steering angles in intervals, a straight-ahead travel can also be taken into account. Accordingly, it is possible to use further driving situations to determine the tread profile values.

In a further embodiment of the method, determining the profile values is preceded by a step of determining reference values for a standard tire, which are calculated for each travel parameter.

Accordingly, a standard tire corresponding to, for example, a brand-new tread profile value can be used as a reference. The number of revolutions determined by the sensor means are then evaluated in comparison to those values that would be obtained with a standard tire. Thus, a simple calibration of the rotational speed determined by the sensor means is possible.

In a further embodiment of the method, a change in a path length of the wheels is calculated for each travel curve parameter, wherein a distinction is made between a curve-inside and a curve-outside case.

Since the inside and the outside of the wheel on different wheels go through different distances, the number of revolutions varies depending on the driving curve parameters. From the difference in the number of revolutions it is possible to infer the tire profile values.

In a further embodiment of the method, the profile values are determined from a plurality of straight-ahead drives by evaluating wheels arranged on different sides of the motor vehicle with respect to a difference in the number of revolutions.

Even when driving straight ahead, differently worn tires rotate at different speeds so that a profile value for each tire can be determined from the comparison of opposing wheels by considering the difference in the number of revolutions.

In a further embodiment of the method, the sensor means is provided as a speed encoder of an anti-lock brake system.

Modern vehicles are almost all equipped with an anti-lock braking system. By using the RPM encoders of the antilock braking system as the sensor means, no additional components need to be provided, which enables a cost effective implementation of the invention.

In a further embodiment of the method, the output profile value is determined in relation to a standard tire.

Accordingly, for example, the profile value can be output as a percentage wear or the like, which represents a clear information for the driver of the motor vehicle.

In a further embodiment of the method, the output takes place in adjustable steps, preferably at intervals of one millimeter.

The indication of the profile value in a scale is also known to the driver of the motor vehicle and allows, for example, the direct link with legal standards. The described method for determining a tire tread value within a driving operation of a motor vehicle and the advantageous embodiments may be provided in a motor vehicle, in particular in a control unit. Expediently, the control unit has a storage means with a computer program stored thereon, the computer program serving to carry out the method according to the invention.

The control unit may have a digital microprocessor unit (CPU) data-connected to a memory system and a bus system, a random access memory (RAM) and a memory means. The CPU is adapted to execute instructions executed as a program stored in a memory means, to detect input signals from the data bus and to output output signals to the data bus. The storage system may have various storage media such as optical, magnetic, solid state and other non-volatile media on which a corresponding computer program for carrying out the method and the advantageous embodiments is stored. The program may be arranged to be capable of embodying the methods described herein, such that the CPU performs the steps can perform such procedures and thus can control the motor vehicle.

Suitable for performing a method is a computer program having program code means for performing all the steps of any one of the claims when the program is run on a computer.

The computer program may have program code means for carrying out all the steps of the method and, if appropriate, the embodiments mentioned in the subclaims when the program is executed on a computer. The computer program can be read in with simple means in existing control units and used.

Provided for this purpose is a computer program product with program code means, which are stored on a computer-readable data carrier in order to carry out the method according to any of the claims, when the program product is executed on a computer. The computer program can also be integrated as a retrofit option in control units.

Furthermore, a motor vehicle is specified with a control unit, wherein the control unit has a storage means with a computer program stored thereon, the computer program being equipped to carry out the method described above

• – Mittel zum wiederholten Erfassen eines Lenkeinschlags des Kraftfahrzeugs, wobei jedem Lenkeinschlag ein Fahrkurvenparameter zugeordnet wird,
• – Mittel zum Bestimmen von Umdrehungszahlen für jeden Fahrkurvenparameter mittels Sensormittel, die jeweils einem einen profilierten Reifen aufweisendem Rad zugeordnet sind,
• – Mittel zum Speichern einer vorgegebenen Anzahl der Umdrehungszahlen als Funktion der Fahrkurvenparameter,
• – Mittel zum Berechnen von Profilwerten jeweils gegenüberliegender Reifen in Abhängigkeit der Fahrkurvenparameter und der Umdrehungszahlen, und
• – Mittel zum Ausgeben der Profilwerte.

A further aspect of the invention relates to an apparatus for determining a tire tread value within a driving operation of a motor vehicle, comprising the following steps:

• Means for repeatedly detecting a steering angle of the motor vehicle, wherein each steering angle is assigned a travel curve parameter,
• Means for determining revolution numbers for each lane parameter by means of sensor means each associated with a wheel having a profiled tire,
• Means for storing a predetermined number of revolution numbers as a function of the driving curve parameters,
• - means for calculating profile values of respectively opposite tires as a function of the driving curve parameters and the rotational speeds, and
• - means for outputting the profile values.

In one embodiment of the apparatus, the trajectory parameters are formed by combining the steering angles at multiple intervals, the intervals comprising equal ranges of steering angles, different ranges of steering angles, overlaps of steering angles, or omissions of steering angles.

In a further embodiment of the apparatus, the travel curve parameters include a straight-ahead travel.

In a further embodiment of the apparatus, determining the profile values is preceded by a step of determining reference values for a standard tire, which are calculated for each travel parameter.

In a further embodiment of the apparatus, a change in a path length of the wheels is calculated for each travel curve parameter, a distinction being made between a curve-inside and a curve-outside case.

In a further embodiment of the apparatus, the profile values are determined from a plurality of straight-ahead drives by evaluating wheels arranged on different sides of the motor vehicle with respect to a difference in the number of revolutions.

In a further embodiment of the apparatus, the sensor means is provided as a speed encoder of an anti-lock braking system.

In a further embodiment of the apparatus, the output profile value is determined in relation to a standard tire.

In a further embodiment of the apparatus, the output takes place in adjustable steps, preferably at intervals of one millimeter.

Hereinafter, an embodiment will be explained with reference to the drawing. Show it:

1 a schematic representation of a motor vehicle in a front view in carrying out the method according to the invention,

2 a schematic representation of a trajectory of a motor vehicle in a curve in carrying out the method according to the invention,

3 a schematic representation of a motor vehicle in a plan view in carrying out the method according to the invention, and

4 an embodiment of the method according to the invention in a flowchart.

In the figures, identical or functionally identical components are provided with the same reference numerals. In 1 is a motor vehicle 1 in a Fronansicht shown. The motor vehicle has a left front tire 2 and a right front tire 3 on. As in 1 is shown, each wheel is assigned a sensor means, wherein the first sensor means 4 the left front tire 2 and the second sensor means 5 the right front tire 3 assigned. In the first sensor means 4 and the second sensor means 5 These are tachometers of an anti-lock braking system, which usually deliver about 50 pulses per revolution of the wheel. These pulse trains are called output signals of the sensor means 4 . 5 provided.

Every tire 2 . 3 For example, a tire tread value may be assigned, for example, as the tread depth of a tread on a tread 2 . 3 let represent. In 1 is for the left front tire 2 the tread profile value 6 schematically drawn.

During operation, the motor vehicle 1 along a roadway 7 moves, as in 2 is shown. The roadway 7 In one example, it has the shape of a curve 8th with an internal roadway boundary 9 and an outer roadway boundary 10 on. When driving through the curve 8th and the roadway 2 can the vehicle 1 a travel curve parameter 11 can be assigned, which can be determined as a deviation from a straight ahead. This can be a steering angle of the motor vehicle 1 while going through the curve 8th be recorded.

In a preparatory step, a repeated detection of the steering angle of the motor vehicle now takes place 1 , with each steering angle of the Fahrkurvenparameter 11 is assigned. The driving curve parameters thus obtained 11 are formed by combining the steering angles at multiple intervals, the intervals including equal ranges of steering angles, different ranges of steering angles, overlaps of steering angles, or omissions of steering angles. The travel curve parameters 11 but may also include a straight ahead. It should be noted that the repeated detection is carried out until a sufficient number of measured values are present. This period can be, for example, several weeks. The accuracy of the profile value detection is to be set in the range of millimeters, for example.

In 3 is a plan view of the motor vehicle 1 shown schematically illustrates further components for carrying out the method according to the invention. The car 1 points next to the left front tire 2 together with associated first sensor means 4 and the right front tire 3 together with associated second sensor means 5 a left rear tire 12 and a right rear tire 13 on. The left rear tire 12 is a third sensor means 14 and the right rear tire 13 a fourth sensor means 15 assigned. The first to fourth sensor means 4 . 5 . 14 . 15 are about first to fourth connections 16 . 17 . 18 . 19 with a control unit 20 connected. Furthermore, the motor vehicle 1 a steering wheel 21 on, that over a steering gear 22 with a fifth sensor means 23 connected via the fifth connection 24 on the steering wheel 21 certain steering angle to the control unit 20 passes.

The inventive method now comprises, as in 4 is shown, in a first step 100 the repeated detection of a steering angle of the motor vehicle 1 where each steering angle is a trajectory parameter 11 is assigned. In a second step 101 determining the number of revolutions for each lane parameter 11 by means of the first to fourth sensor means 4 . 5 . 14 . 15 , each one a profiled tire 2 . 3 . 12 . 13 are associated with wheel.

Subsequently, in step 102 storing a predetermined number of revolution numbers as a function of the trajectory parameters 11 , Now in step 103 calculating profile values 6 each opposite tire 2 . 3 and 12 . 13 depending on the driving curve parameters 11 and the number of revolutions performed. Finally, in step 104 in the control unit 20 an output of the profile values 6 as a signal 25 ,

When driving it comes due to cornering with different curve radii to differ in length routes between left and right steered wheel. The left and right side of each route or the respective effective Fahrradius with the associated steering wheel can be under consideration of the geometric distance of Determine viewing wheels with integration methods.

It now turns out that the means of the first sensor means 4 and the second sensor means 5 gained numbers of revolutions between the left front wheel 2 and the right front wheel 3 for driving through curves 8th differ by an amount dU. This dU corresponds to a number of pulses of the first sensor means 4 and the second sensor means 5 , Nominal tire tread without tire wear gives the value dUn. If the corresponding bicycle radius is passed with tires worn down by 1 mm, the result is a value that deviates too much from dU-1 mm.

For example, a 10m radius circle with a 1mm worn tire gives a difference of 1.5 pulses when using a pulse generator of 48 pulses per revolution over the nominal tire. A wear around 2 mm leads in the same situation to a difference value of 3 pulses.

A similar result is obtained even when looking at the right rear tire 13 and the left rear tire 12 , so that when cornering the inside and the outside wheel of an axle are considered. A difference value is also obtained when driving straight ahead with wheels of different profile wear. Here you can also include the front and rear wheels in the evaluation individually and is not bound to the evaluation of an axis.

With the method presented here, it is now possible to determine an indication for tire wear from an initial state. Tire changes can also be determined with this method.

Although some possible embodiments of the invention have been disclosed in the foregoing description, it is to be understood that numerous other variants of embodiments exist through the possibility of combining all of the foregoing and further all of the obvious technical features and embodiments. It is further understood that the embodiments are to be understood as examples only, which in no way limit the scope, applicability and configuration. Rather, the preceding description would like to show the skilled person a suitable way to realize at least one exemplary embodiment. It should be understood that in an exemplary embodiment, numerous changes in the function and arrangement of the elements may be made without departing from the scope and equivalents disclosed in the claims.

LIST OF REFERENCE NUMBERS

1

motor vehicle

2

left front wheel

3

right front wheel

4

first sensor means

5

second sensor means

6

profile value

7

roadway

8th

Curve

9

internal roadway boundary

10

outer roadway boundary

11

Travel curve parameters

12

left rear wheel

13

right rear wheel

14

third sensor means

15

fourth sensor means

16

first connection

17

second connection

18

third connection

19

fourth connection

20

control unit

21

steering wheel

22

steering gear

23

fifth sensor means

24

fifth connection

100-104

steps

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007029870 A1 [0005]

Claims (12)

Method for determining a tire tread value ( 6 ) within a driving operation of a motor vehicle ( 1 ), comprising: - repeatedly detecting a steering angle of the motor vehicle ( 1 ), wherein each steering angle is a Fahrkurvenparameter ( 11 ), determining number of revolutions (U) for each travel parameter ( 11 ) by means of sensor means ( 4 . 5 . 14 . 15 ), each one a profiled tire ( 2 . 3 . 12 . 13 ) are assigned to the wheel, - storing a predetermined number of revolution numbers (U) as a function of the travel curve parameters ( 11 ), - calculating profile values ( 6 ) of respectively opposite tires as a function of the travel curve parameters ( 11 ) and the revolution numbers (U), and - output the profile values ( 6 ). Method according to Claim 1, in which the travel curve parameters ( 11 ) are formed by combining the steering angles at multiple intervals, the intervals including equal ranges of steering angles, different ranges of steering angles, overlaps of steering angles, or omissions of steering angles. Method according to Claim 1 or 2, in which the travel curve parameters ( 11 ) include a straight ahead. Method according to one of claims 1 to 3, wherein determining the profile values ( 6 ) precedes a step of determining reference values for a standard tire which is determined for each travel curve parameter ( 11 ) be calculated. Method according to one of Claims 1 to 4, in which for each travel curve parameter ( 11 ) a change in a path length of the wheels is calculated, wherein a distinction is made between a curve inside and a curve outside case. Method according to one of Claims 1 to 5, in which the profile values ( 6 ) can be determined from a large number of straight-ahead drives by moving on different sides of the motor vehicle ( 1 ) arranged wheels are evaluated with respect to a difference in the number of revolutions. Method according to one of Claims 1 to 6, in which the sensor means ( 4 . 5 . 14 . 15 ) is provided as a speed encoder of an anti-lock brake system. Method according to one of Claims 1 to 7, in which the output profile value ( 6 ) in relation to a standard tire. Method according to Claim 8, in which the output takes place in adjustable steps, preferably at intervals of one millimeter. Motor vehicle with a control unit, wherein the control unit ( 20 ) has a memory means with a computer program stored thereon, the computer program being equipped to carry out a method according to one of claims 1 to 9. Computer program for carrying out a method according to one of Claims 1 to 9. A computer program product comprising program code means stored on a computer readable medium for carrying out the method of any of the preceding claims 1 to 9 when the program code means are executed on a computer.

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