METHOD FOR DETECTING A FAULTY ARRANGEMENT OF A SENSOR MODULE IN A SENSOR MODULE HOLDER IN A TYRE MONITORING SYSTEM OF A VEHICLE AND TYRE MONITORING SYSTEM

Abstract

Disclosed are a method and a system for detecting a faulty arrangement of a sensor module in a sensor module holder in a tire of a vehicle equipped with a tire monitoring system. The detection of a faulty arrangement of a sensor module may be performed by ascertaining on the basis of a comparison of the operating parameters determined by the sensor modules of the tire monitoring system that there is for this sensor module a discrepancy, dependent on a speed of the vehicle, between the operating parameter and an operating parameter to be expected for this sensor module.

Claims

1. A method for detecting a faulty arrangement of a sensor module in a sensor module holder in a tire of a vehicle equipped with a tire monitoring system, the tire monitoring system having multiple sensor modules arranged in a respective sensor module holder of a respective tire of the vehicle, which respectively determine in dependence on a sensor-detected acceleration at an arrangement location of the sensor module an operating parameter of the tire in question and send it wirelessly to a receiving and evaluating device arranged in the vehicle, with a detection of a faulty arrangement of a sensor module of the sensor modules in the sensor module holder in question being performed by: ascertaining based on a comparison of the operating parameters determined by the sensor modules that there is for this sensor module a discrepancy, dependent on a speed of the vehicle, between the operating parameter and an operating parameter to be expected for this sensor module.

2. The method as claimed in claim 1, the sensor module holders being respectively designed as a receptacle formed from an elastic material for inserting the respective sensor module.

3. The method as claimed in claim 1, the sensor module holders being respectively fastened on an inner side of a tire tread of the respective tire.

4. The method as claimed in claim 1, the tire monitoring system configured to be a tire pressure monitoring system, the sensor modules respectively detecting a pressure in the respective tire and sending tire pressure information wirelessly to the receiving and evaluating device as an operating parameter of the tire in question.

5. The method as claimed in claim 1, the acceleration respectively detected by the sensors of the sensor modules at the arrangement location of the sensor module in question including at least one of a radial acceleration and a tangential acceleration.

6. The method as claimed in claim 1, the operating parameter respectively determined by the sensor modules being representative of a length of a tire contact area of the tire in question.

7. The method as claimed in claim 6, the operating parameter respectively determined by the sensor modules giving a ratio of the length of the tire contact area to an outer circumference of the tire in question.

8. The method as claimed in claim 1, the ascertainment of the discrepancy taking place in a predetermined partial range of an overall range of the speed of the vehicle that is operationally intended for the vehicle.

9. The method as claimed in claim 1, the ascertainment of the discrepancy including an ascertainment of a discrepancy that changes monotonically with varying speed of the vehicle.

10. A tire monitoring system for a vehicle, comprising multiple sensor modules configured to be arranged in a respective sensor module holder of a respective tire of a vehicle and are respectively configured to determine and wirelessly send an operating parameter of the tire in question in dependence on a sensor-detected acceleration at an arrangement location of the sensor module, a receiving and evaluating device configured to be arranged in the vehicle and further configured to receiver and evaluate the operating parameters of the tires sent by the sensor modules, the receiving and evaluating device further configured to detect a faulty arrangement of a sensor module of the sensor modules in the sensor module holder in question by ascertaining based on a comparison of the operating parameters determined by the sensor modules that there is for this sensor module a discrepancy, dependent on a speed of the vehicle, between the operating parameter and an operating parameter to be expected for this sensor module.

11. The tire monitoring system as claimed in claim 10, the operating parameter respectively determined by the sensor modules being representative of a length of a tire contact area of the tire in question.

12. The tire monitoring system as claimed in claim 11, the operating parameter respectively determined by the sensor modules giving a ratio of the length of the tire contact area to an outer circumference of the tire in question.

13. The tire monitoring system as claimed in claim 10, the ascertainment of the discrepancy taking place in a predetermined partial range of an overall range of the speed of the vehicle that is operationally intended for the vehicle.

14. The tire monitoring system as claimed in claim 10, the ascertainment of the discrepancy including an ascertainment of a discrepancy that changes monotonically with varying speed of the vehicle.

Description

[0070] The invention is described in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings, in which:

[0071] FIG. 1 shows a schematic side view of a vehicle wheel with a tire in which a sensor module held in a sensor module holder is arranged,

[0072] FIG. 2 shows a block diagram of the sensor module from FIG. 1,

[0073] FIG. 3 shows a schematic side view of a detail of the tire from FIG. 1 to illustrate a faulty arrangement of the sensor module in the sensor module holder,

[0074] FIG. 4 shows a further schematic view (cross section) of the detail from FIG. 3,

[0075] FIG. 5 shows a schematic plan view of a vehicle equipped with a tire monitoring system and

[0076] FIG. 6 shows a representation to illustrate the effect of a faulty arrangement of a sensor module on a tire contact quotient determined by means of this sensor module.

[0077] FIG. 1 shows a vehicle wheel W having a rim and a tire 2 mounted on the rim. A rotation of the tire 2 while the vehicle in question is traveling is symbolized by an arrow 3.

[0078] In the tire 2, a sensor module 12 is arranged in a sensor module holder 13 as a component of a tire monitoring system of the vehicle in question, the sensor module holder 13 being designed as a receptacle made of an elastic material (for example rubber) in which the sensor module 12 is inserted.

[0079] In the exemplary embodiment shown, the sensor module holder 13 delimits a cylindrical receiving space in order to receive a correspondingly cylindrically shaped body of the sensor module 12 in it and to fix it by the elastic enclosure of the sensor module body. In this example, the sensor module holder 13 is adhesively bonded on an inner side of a tire tread of the tire 2.

[0080] When the vehicle is being driven, the sensor module 12 determines for example in particular an operating parameter which is representative of a length L indicated in FIG. 1 of a tire contact area of the tire 2.

[0081] FIG. 2 shows a block diagram of the sensor module 12, having a pressure sensor 14 for detecting a pressure sensor signal “p” representative of a pressure in the tire 2, an acceleration sensor 16 for detecting an acceleration sensor signal “a” representative of an acceleration, in the exemplary embodiment shown the radial acceleration, and a temperature sensor 18 for detecting a temperature sensor signal “T” representative of a temperature inside the tire 2.

[0082] The sensor module 12 also has a program-controlled control device 20 (for example a microcontroller) with an associated memory device 22 for storing a program that controls the operation of the control device 20. The control device 20 receives the aforementioned sensor signals p, T, a and, in dependence on these sensor signals, determines in a program-controlled manner multiple tire operating parameters, which are recorded from time to time in a data message D generated by the control device 20 and sent by means of a radio transmitting device 24 in the form of radio transmissions R to a radio receiving device 30 arranged in the vehicle and likewise shown in FIG. 1 and passed on from there to an evaluating device 40.

[0083] In this exemplary embodiment, a receiving and evaluating device is thus formed by the radio receiving device 30 for receiving and decoding the radio transmissions R and the evaluating device 40, which receives the data messages D decoded by the radio receiving device 30 via a digital bus system 32 (for example CAN bus, LIN bus or the like) and then evaluates them or passes on information obtained from them to other parts of the vehicle's electronics.

[0084] In the example shown, the evaluating device 40 is formed by a program-controlled computer unit 42 and an assigned memory unit 44 for storing a program that controls the operation of the computer unit 42. In practice, the evaluating device 40 may for example also be implemented as a partial functionality of a central control device (ECU) that is in any case present in the vehicle in question.

[0085] In the example shown, in particular the tire pressure, the tire temperature, the rotational speed and a tire contact quotient FPQ of the tire 2 are provided as tire operating parameters of the tire 2 which are transmitted to the receiving and evaluating device by means of the radio transmissions D.

[0086] Here, the tire pressure and the tire temperature are determined directly on the basis of the corresponding sensor signals “p” and “T”, whereas the determination of the rotational speed and the tire contact quotient FPQ is based on an evaluation carried out by the control device 20 of the variation over time of the sensor signal “a” representative of the radial acceleration at an arrangement location 4 of the sensor module 12.

[0087] To determine the rotational speed, there is the possibility for example of evaluating the gravitational component of the sensor signal “a” periodically changing with each wheel revolution or for example the possibility of evaluating the frequency of the occurrence of signal characteristics in the sensor signal “a” that occur with each passage of the arrangement location 4 through the footprint (the tire contact area). This also allows determination of the tire contact quotient FPQ, which is defined here as the quotient between the length L indicated in FIG. 1 of the tire contact area and the total circumference of the tire 2.

[0088] Every time the sensor module 12 makes impact on entering the tire contact area and every time the sensor module 12 lifts off on leaving the tire contact area, typical signal characteristics appear in the sensor signal “a”, so that the operating parameter FPQ can be calculated as the quotient between the time span between impact and lifting off and the time span of a complete revolution (360°) of the tire 2.

[0089] In addition to the operating parameters already mentioned, still further operating parameters can be determined by the control device 20 in dependence on the sensor-detected variables and transmitted to the receiving and evaluating device.

[0090] FIGS. 3 and 4 again illustrate on the basis of enlarged (not to scale) representations the arrangement of the sensor module 12 in the sensor module holder 13 at the arrangement location 4 in the tire 2.

[0091] Illustrated here in FIG. 3 is a faulty arrangement of the sensor module 12 in the sensor module holder 13, which cannot be ruled out in practice. In this example, the sensor module 12, viewed in the circumferential direction of the tire 2, is arranged somewhat tilted (with an angle of inclination α).

[0092] Such an incorrect arrangement of the sensor module 12 is generally not a problem for determining the tire pressure and the tire temperature. However, in principle this incorrect arrangement can in particular falsify all of the operating parameters determined by the sensor module 12 in dependence on the detected acceleration (signal “a”), such as here in particular the determined tire contact quotient FPQ. The inclined sensor module 12 is no longer able to detect the radial acceleration as actually intended, but in the situation shown in fact detects an oriented acceleration at the arrangement location 4 that is somewhat inclined with respect to the radial direction.

[0093] The incorrect arrangement of the sensor module 12 illustrated in FIG. 3 leads to a falsification of the result of the sensory detection of the radial acceleration. This fault case thus also affects the function and reliability of the tire monitoring system in which such an incorrectly installed sensor module 12 is integrated.

[0094] The present invention aims to detect an incorrect arrangement of a sensor module as shown for example in FIG. 3, so that for example operating parameters supplied by the sensor module in question may be assessed by the receiving and evaluating device as completely or partially invalid and/or may be excluded from further use.

[0095] Illustrated by contrast in FIG. 4 is a faultless or correct arrangement of the sensor module 12 in the sensor module holder 13.

[0096] FIG. 5 shows a vehicle 1 equipped with a tire monitoring system according to one embodiment, which in the example shown is a two-track four-wheeled motor road vehicle (for example a car) with two front wheels W1, W2 and two rear wheels W3, W4. The wheels W1 to W4 are respectively fitted with a tire in which a sensor module 12-1, 12-2, 12-3 or 12-4 is arranged. The associated sensor module holders are designated in FIG. 5 by the reference numerals 13-1 to 13-4.

[0097] In the following description of the tire monitoring system of FIG. 5, it will be assumed that each of the vehicle wheels W1 to W4 is designed as already described with reference to FIGS. 1 to 4 for the vehicle wheel W (FIG. 1), and therefore each of the sensor modules 12-1 to 12-4 together with the associated sensor module holders 13-1 to 13-4 are also designed and function as already described with reference to FIGS. 1 to 4 for components 12 and 13.

[0098] The tire monitoring system used in the vehicle 1 includes the sensor modules 12-1 to 12-4, which are respectively arranged in an assigned sensor module holder of the sensor module holders 13-1 to 13-4 of the respective tire of the vehicle 1, not shown in FIG. 5, and are respectively designed to determine in dependence on inter alia the sensor-detected acceleration (here the radial acceleration) multiple operating parameters of the tire in question, including in particular the tire contact quotient FPQ, and to send them wirelessly (as radio transmissions R1 to R4).

[0099] The tire monitoring system also includes the receiving and evaluating device arranged in the vehicle 1 for receiving and evaluating the operating parameters sent by the sensor modules 12-1 to 12-4.

[0100] The receiving and evaluating device, here consisting of the radio receiving device 30 and the program-controlled evaluating device 40 connected to it via the communication bus 32, is designed to detect a faulty arrangement of one of the sensor modules 12-1 to 12-4 (cf. for example FIG. 3) in the sensor module holder 13-1, 13-2, 13-3 or 13-4 in question by ascertaining on the basis of a comparison of the tire contact quotients FPQ determined by all of the sensor modules 12-1 to 12-4 that there is for this sensor module a discrepancy, dependent on the speed of the vehicle 1, between the tire contact quotient FPQ and a tire contact quotient FPQ to be expected for this sensor module.

[0101] In this detection, a kind of plausibility check for example may be carried out in such a way that it is respectively checked for each of the sensor modules 12-1 to 12-4 whether or not the FPQ value supplied by the sensor module in question is plausible in view of the FPQ values supplied by the other three sensor modules. In the case of an ascertained implausibility, equivalent to a significant discrepancy (for example lying above a predetermined threshold) between the FPQ value and an FPQ value to be expected with a proper sensor module arrangement, this is assessed as an incorrect arrangement of the sensor module in question in the case where the discrepancy is dependent on the speed of the vehicle 1.

[0102] To determine the speed of the vehicle 1, in the exemplary embodiment shown, wheel sensors (speed sensors) 10-1 to 10-4 installed in the vehicle in a manner respectively assigned to one of the wheels W1 to W4 are used. Sensor signals S1 to S4 supplied by these wheel sensors 10-1 to 10-4 are transmitted here in a wired manner (for example using the digital bus system 32) to the evaluating device 40, which determines the current vehicle speed from them.

[0103] On the basis of the knowledge of the current vehicle speed, the evaluating device 40 continuously collects data while the vehicle 1 is being driven, including the FPQ values supplied by the sensor modules 12-1 to 12-4, in each case in association with a relevant identification of the supplying sensor module (for example encoded in the respective radio transmission R1, R2, R3 or R4) and in association with the speed of the vehicle 1 applicable at the point in time in question. The explained detection is carried out by the evaluating device 40 on the basis of these data.

[0104] If, for example, the sensor module 12-4 installed in the wheel W4 is incorrectly arranged and the plausibility of the FPQ value supplied by the sensor module 12-4 is checked as part of the detection method, the evaluating device 40 can use the data collected for different vehicle speeds to ascertain for example a discrepancy between the FPQ value and an FPQ value to be expected. The FPQ value to be expected can be determined for example according to a predetermined algorithm, running in the evaluating device 40, for example from the FPQ values supplied by the other sensor modules 12-1 to 12-3. Before a final ascertainment of the incorrect arrangement, however, a check is also made here as to whether or not the ascertained discrepancy is dependent on the vehicle speed in a manner defined by the detection method (for example discrepancy increases/decreases as the vehicle speed increases).

[0105] FIG. 6 illustrates by way of example the effect of an incorrect arrangement of a sensor module on the FPQ value determined by this sensor module.

[0106] In FIG. 6, the FPQ value is plotted in the upward direction. The FPQ values represented by dots or a solid line are those of a properly arranged sensor module. By contrast, the dashed line illustrates the FPQ values of a sensor module incorrectly arranged in the same driving situation.

[0107] In FIG. 6, the five partial representations “A” to “E” initially illustrate the dependence of the FPQ value on a wheel load currently acting on the tire in question. The individual partial diagrams A to E are based on the following wheel loads: 525 kg (A), 600 kg (B), 675 kg (C), 750 kg (D) and 825 kg (E). It can be seen from this that the greater the wheel load, the greater the FPQ value.

[0108] Within each of the partial diagrams A to E, three results are respectively given for the FPQ value, characterized by an index i with i=1, 2 or 3, the index i being representative of the vehicle speed in question as follows: 40 km/h (i=1), 60 km/h (i=2) and 90 km/h (i=3). It can be seen from this that, in the example shown for the properly arranged sensor module, there is a certain dependence of the FPQ value on the vehicle speed. In the example shown, the FPQ value tends to increase somewhat as the vehicle speed increases.

[0109] For the FPQ value of the incorrectly arranged sensor module (dashed line), on the other hand, there is a significant discrepancy with respect to the FPQ value to be expected (solid line), this discrepancy being dependent on the vehicle speed. In the example shown, irrespective of the wheel load, the discrepancy in the observed speed range from 40 km/h to 90 km/h decreases monotonically as the vehicle speed increases.

[0110] In the example shown, this discrepancy is relatively great at a speed of 40 km/h (i=1) and almost zero at a speed of 90 km/h (i=3).

[0111] Transferred to the exemplary embodiment of a tire monitoring system shown in FIG. 5, in this tire monitoring system it may be provided for example that, in the partial range of 40 km/h to 90 km/h of the vehicle speed for the sensor module in question, an FPQ value decreasing monotonically as the vehicle speed increases is obtained as a criterion for the ascertainment of an incorrectly arranged sensor module (12-1, 12-2, 12-3 or 12-4).

LIST OF REFERENCE SIGNS

[0112] 1 Vehicle [0113] W Vehicle wheel [0114] 2 Tire [0115] 3 Arrow [0116] 4 Arrangement location [0117] L Length of the tire contact area [0118] FPQ Tire contact quotient [0119] 10-1 Wheel sensor [0120] 10-2 Wheel sensor [0121] 10-3 Wheel sensor [0122] 10-4 Wheel sensor [0123] 12 Sensor module [0124] 13 Sensor module holder [0125] 14 Pressure sensor [0126] p Pressure sensor signal [0127] 16 Acceleration sensor [0128] a Acceleration sensor signal [0129] 18 Temperature sensor [0130] T Temperature sensor signal [0131] 20 Control device [0132] 22 Memory device [0133] 24 Radio transmitting device [0134] D Data message [0135] R Radio transmissions [0136] 30 Radio receiving device [0137] 32 Bus system [0138] 40 Evaluating device [0139] 42 Computer unit [0140] 44 Memory unit