DE102007016472A1 - Motor vehicle tire status monitoring method, involves identifying wheel rotation acceleration of defect wheel after identification of pressure leakage, and producing signal wheel rotation acceleration exceeds threshold value - Google Patents

Abstract

The method involves detecting a wheel rotational speed of a wheel of a motor vehicle. Tire pressure leakage is identified when the wheel rotation speed exceeds a normal range. Wheel rotation acceleration of the defect wheel is determined after identification of the pressure leakage. A signal is produced when the wheel rotation acceleration or a parameter interrelated with the acceleration exceeds a threshold value. An independent claim is also included for a regulation-and-control device for executing a method for monitoring a tire status of a motor vehicle.

Description

The The invention relates to a method of monitoring of the tire condition in vehicles according to the preamble of the claim 1.

State of the art

In the DE 103 03 492 A1 Such a method is described in which, for monitoring the tire condition, the rotational movements of the driven wheels of a motor vehicle are detected, wherein a tire pressure loss is detected in a wheel, if this wheel shows a different wheel speed for a long time. Background is the physical principle, according to which flattened wheels have a higher rotational speed. In order to exclude a falsification of the result in the detection of the tire pressure loss, according to the DE 103 03 492 A1 additionally takes into account the drive torque in the tire pressure loss detection, which leads to an at least partial compensation of the rolling circumference of the defective tire.

With the in the DE 103 03 492 A1 Although described method is a safe detection of tire pressure loss possible. However, there is a problem with defective tires, that while the use of so-called run-flat tires still a limited residual distance can be continued with reduced speed, but if the speed or the remaining distance exceeds the risk of total destruction of the tire and thus accompanied by a high risk of accidents.

Disclosure of the invention

Of the Invention is based on the object critical driving conditions to prevent at a tire pressure loss.

These Task is according to the invention with the features of claim 1 solved. The subclaims give appropriate training.

at the method according to the invention for monitoring of the tire condition in vehicles are in a first step detects the wheel rotational speeds of the wheels, wherein a tire pressure loss is detected, provided the wheel speed of one of the wheels or a related size outside a standard range. Is at a wheel Pressure loss has been determined, the wheel spin determined at least the defective wheel and a signal for further processing generated in the event that the wheel spin or a related size outside an associated normal range, in particular exceeds a limit.

In order to a two-stage control and warning procedure can be realized. The first warning level is reached as soon as a tire loses pressure Examination of the wheel speeds is determined. At least in run-flat tires but then despite pressure loss, the Possibility of a limited residual maturity, for example 100 up to 200 km with a prescribed maximum speed too drive, which is usually at 80 km / h. This residual distance Can be completed despite pressure loss without critical driving conditions occur.

Around the danger of complete destruction of the Tire, in particular due to high thermal loads, the become relevant for tires with pressure loss, in time to recognize after wheel pressure has been detected, the wheel spin is continuously increasing determined at least the defective wheel and a second, for further processing generates suitable signal in the event that the wheel spin or the related size outside the normal range. The wheel spin the wheel with broken tire is used as a measure of a threatening, complete destruction of the tire due high thermal load used. The acceleration value increases strongly before the destruction of the tire; this increase can by evaluating the wheel spin or the related Value are detected, whereupon a signal is generated, the is used either for display and / or other further processing. For example, it is possible for the driver to do this second prompt for immediate stop to critical To avoid driving conditions. In addition, the signal can in a vehicle assistance system, for example in the anti-lock braking system or further processed in the electronic stability program become.

The Invention is not limited to run-flat tires. in principle The inventive method can also be applied to conventional wheels Tires are used, as in this case at least one only relatively low pressure loss another drive for a limited distance and at limited speed before reaching critical driving conditions is possible. The distinction between conventional tires and run-flat tires can vary by different set limits are met.

The reference or limit value with which the wheel rotational acceleration of the defective tire is compared, according to an advantageous embodiment during operation of the Raddrehbeschleu determined at least one additional wheel of the vehicle. The wheel spin accelerations of all wheels are expediently determined, the acceleration values of the intact wheels being used as the basis for calculating the limit value. In this case, it has proved to be advantageous to calculate the arithmetic mean of the wheel spin accelerations of the intact wheels.

In the determination of the limit value for the wheel spin can further vehicle state variables and / or vehicle parameters. As a complete Destruction of the defective tire due to high thermal load also from external conditions or the driving style It may be useful to set the limit during operation adapt. So it is for example advantageous with increasing Vehicle speed to lower the limit, because due the centrifugal forces in the wheel increasing with second power with progressive speed a progressive destruction progress is to be expected. Alternatively or cumulatively but can also takes into account other state variables or parameters especially the outside temperature.

According to a further expedient embodiment, the method can also be carried out in such a way that in the second phase of the method, ie after detected tire defect, first the wheel spin is examined and when exceeding an acceleration limit value, a count value is counted up as a time function, whereby a signal is generated. if the count exceeds an assigned limit. In this embodiment, therefore, two limit values are taken into account in the second phase of the method, namely the acceleration limit value and the limit value assigned to the count value, which offers the advantage that the dependency on the further state variables or parameters lies above the count value or the latter associated limit value can be considered. It is thereby achieved an equalization between the acceleration limit and other factors influencing the state of defective tire. Thus, it is possible, in particular, to make the time-dependent count-up value dependent on the further state variables or parameters, for example such that the incrementing vehicle speed increases the count value more strongly, so that the corresponding limit value is correspondingly more rapidly exceeded. This dependency of the count on the vehicle speed can be realized in a very simple manner by dividing the vehicle speed into different categories and incrementing the count with differently sized increments, depending on the current speed category. For example, if the vehicle is traveling below the permitted speed, the increment can occur 1 are set, whereas at higher vehicle speeds the increment occurs 2 . 3 or even higher values are set, so that the limit is reached faster.

The Wheel spin, preferably for each vehicle wheel can be determined both computationally and with the aid of sensors, in particular be determined by acceleration sensors.

Further Advantages and expedient designs are the other claims, the description of the figures and to take the drawing, in which the procedure for monitoring of the tire condition is shown.

The method shown in the figure for detecting a tire defect in motor vehicles is based on monitoring the wheel rotational speeds ω _{ij of} the wheels and the wheel spin acceleration ω. _ij at least the defective wheel. In a first method step 1, first the wheel speeds or rotation speeds ω _{ij of} all wheels of the motor vehicle are determined, in particular by measurement by means of suitable sensors. Thereafter, in a second process step 2 the wheel speeds ω _ij of each wheel with a speed limit value ω _{Li with} compared, one makes use of the fact that in the case of a tire defect increases the wheel speed of the defective wheel. If one of the wheel rotational speeds ω _ij exceeds the set limit value ω _{L i ,} then a defect exists at the relevant tire and the process continues to the method step 3 following the yes branching. Otherwise, according to the no-branch again to the block 1 have returned and the wheel rotational speeds ω _{ij are} determined again at cyclic intervals and subjected to a test.

In the next process step 3 A first warning signal is issued to indicate the defective tire. In addition, further signals can be generated, which can lead to further consequences in a regulating or control device of the vehicle, for example, to a limitation of the maximum permissible vehicle speed.

Since, in particular, when using so-called run-fiat tires in the event of a defect, a drive for a limited residual distance with limited speed is possible, but the limits set to avoid complete destruction of the tire may not be exceeded, will be further procedural steps in the following carried out with the aim of getting out Recognizing destruction and to generate a warning in time. This is done on the basis of the wheel spin ω. _{ij of} the defective wheel in the next step 4 is determined, either from a measurement using a sensor, in particular an acceleration sensor, or in a mathematical manner by differentiation of the wheel speed ω _{ij of} the wheel in question.

After determining the current wheel spin ω. _ij becomes in the following process step 5 an associated acceleration limit ω. _Limit determined. This is expediently carried out in such a way that in the preceding method step 4 the wheel spin accelerations ω _{ij of} all wheels are determined and in the method step 5 the acceleration limit ω. _{Limit is} calculated from the arithmetic mean of the individual wheel accelerations ω _{ij of} the intact wheels.

In the next process step 6 a query is started as to whether the wheel spin value ω. _{ij of} the defective wheel the determined limit ω. _Limit exceeds. This query is based on the finding that the acceleration value of the defective tire rises relatively quickly shortly before reaching complete destruction. To the limit ω. _Limit can still add a tolerance range.

If the query according to method step 6 shows that the wheel spin ω. _{ij of} the defective wheel has not yet exceeded the assigned limit value, the no-branch is again at the beginning of the query according to method step 6 returned and run this query again at cyclic intervals. If the vehicle before reaching the limit ω. _Limit is eliminated, a follow-up of the procedure is unnecessary.

On the other hand, the query results by method step 6 in that the wheel spin ω. _{ij of} the defective wheel, the acceleration limit ω. _{Limit has} exceeded, will move to the next step 7 in which a count count is initialized and set to the value zero. This count value count thus depends on the acceleration value of the defective wheel, since the initialization and the counting up are carried out according to the further method steps only in the event that the acceleration limit value ω. _Limit of the acceleration value ω. _{ij of} the defective wheel is reached.

In the next process step 8th an increment incr is set as a function of the vehicle longitudinal speed v _x . The height of the increment depends directly on the current vehicle speed, the increment incr being set to the lowest value 1 if the vehicle speed is below the maximum permissible limit speed defined for the run-flat case (as a rule 80 km / h ), and set to a higher value if the current vehicle speed exceeds the permissible limit speed. In this case, the value incr increases to different values depending on the degree of exceeding the limit speed.

In the next process step 9 Count count is incremented by adding count count from the previous cycle and increment incr previously determined. In the following process step 10 a query is made as to whether count count exceeds an associated limit count _limit . This limit count _Linit can be defined or calculated. It is possible to specify a fixed limit count _limit , which is reached faster or slower depending on the size of the increment incr, whereby the limiting value count _limit is reached faster in the event of exceeding the permissible speed.

Returns the query in the process step 10 in that the current count value count has not yet reached the limit value count _limit , the no-branching becomes the procedural step again 8th returned and the increment incr set again as a function of the current vehicle speed. If the vehicle speed v _x has meanwhile changed, this results in a corresponding change in the increment incr.

On the other hand, the query results in the method step 10 in that the current count value count has exceeded the limit value count _limit , it must be assumed that the tire is being progressively destroyed. It will be the next procedural step 11 continued and issued a second warning signal, possibly also another signal processing in the control or control unit of the vehicle comes into consideration, in particular a loading of a driver assistance system.

When determining the increment incr after process step 8th Other vehicle or environmental state variables or parameters can also be taken into account, for example the ambient temperature.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10303492 A1 [0002, 0002, 0003]

Claims (12)

Method for monitoring the tire condition in vehicles, in which the wheel rotational speeds of the wheels are detected and a tire pressure loss is detected, if the wheel speed (ω _ij ) of a wheel or a variable to be determined out of a normal range, characterized in that after pressure loss detected the Wheel spin (ω _ij ) at least the defective wheel is determined, wherein a signal is generated if the wheel spin (ω _ij ) or a related size (count) exceeds a limit (ω _{Limi t} , count _limit ). A method according to claim 1, characterized in that the wheel acceleration (ω. _Ij) determined at least one further wheel and the calculation of the limit value (ω. _Limit) is assumed. A method according to claim 2, characterized in that the Raddrehbeschleunigungen of all other wheels determined and the calculation of the limit value (ω. _Limit ) are based. The method of claim 2 or 3, characterized in that determined from the wheel spins of at least two other wheels and the average value as a limit value (ω. _Limit) is used. A method according to any one of claims 1 to 4, characterized in that in the determination of the limit value (ω. _Limit) incorporate more state variables (v _x) and / or parameters. A method according to claim 5, characterized in that with increasing vehicle longitudinal speed (v _x ) of the limit value (ω. _Limit ) is reduced. A method according to any one of claims 1 to 6, characterized in that on exceeding an acceleration limit value (ω. _Limit) a count value (count) is incremented, whereby a signal is generated when the count value (count) an associated limit value (count _limit) exceeds , A method according to claim 7, characterized in that the count value (count) depends on further state variables (v _x ) and / or parameters. A method according to claim 8, characterized in that with increasing vehicle longitudinal speed (v _x ), the count value (count) increases more. Method according to one of claims 1 to 9, characterized in that at least one wheel acceleration (ω. _Ij) calculated from the wheel speed (ω _ij) is determined. Method according to one of Claims 1 to 10, characterized in that at least one wheel rotational acceleration (ω _ij ) is measured by means of an acceleration sensor. Control device for carrying out the Method according to one of claims 1 to 11.