FR2951850A1 - METHOD FOR LOCATING WHEELS OF A MOTOR VEHICLE, LOCATION DEVICE AND PRESSURE MONITORING SYSTEM FOR CORRESPONDING TIRES - Google Patents

Abstract

The invention relates to a method for locating the wheels (R1, R2, R3, R4) of a motor vehicle, characterized in that it comprises the following steps: - a data indicative of a displacement of each wheel is calculated ( D1, D2, D3, D4), - a left / right side is determined on which each wheel (S1, S2, S3, S4) is located; - a front wheel of a rear wheel is discriminated according to the results of comparing the fact that a directional front wheel travels a distance greater than a rear wheel, - locating a wheel by combining the displacement information (D1, D2, D3, D4) and left / right side (S1, S2 , S3, S4) of the wheel

Description

The invention relates to a method for locating the wheels of a motor vehicle and a corresponding locating device. BACKGROUND OF THE INVENTION The invention relates to a method for locating the wheels of a motor vehicle and to a corresponding locating device. More particularly, such a method is implemented in a tire pressure monitoring system of the vehicle.

In a tire pressure monitoring system, each tire is equipped with a pressure sensor and a radiofrequency transmitter, which emits tire pressure data, a pressure value or an insufficient pressure indication. The transmitter also transmits an identifier code which makes it possible to discriminate it from the transmitters of the other tires. Therefore it would be sufficient, in principle, to match each transmitter code with a location data stored centrally in the vehicle, this step being done on the assembly line, in order to be able to indicate to the dashboard which tire is faulty. However, this does not take into account the various changes of tires, interversions, equipment and equipment in snow tires, and others occurring during the life of the vehicle. The invention therefore aims to allow to locate automatically the tire sending a given pressure signal simply and reliably. For this purpose, the subject of the invention is a method according to claim 1. The term "wheel" here refers to the assembly formed by a tire and a rim. Indeed, the four wheels of a vehicle do not rotate at the same speed for different reasons. Especially when cornering, the directional front wheels move more than the rear wheels. Thus, the position of each wheel of a vehicle is detected simply according to the direction of rotation and displacement of the wheel. Some vehicles have directional rear wheels but to a lesser extent than the front wheels which therefore make more displacement than the

BRT0489 AFR0634 rear wheels. Other features and advantages of the invention will emerge from the following description, given by way of example, without limitation, with reference to the appended drawings in which: FIG. 1 schematically represents a tire pressure monitoring system equipping a motor vehicle, and Figure 2 schematically shows the steps of the locating method. In these figures, identical elements bear the same references.

A tire pressure monitoring system 1 fitted to a motor vehicle (not shown) is schematically illustrated in FIG. 1. This monitoring system 1 comprises a central unit 3 and four wheel transmitters E1 to E4 provided with sensors 5 of the invention. pressure of the tires placed on the rim or the tire of a wheel R1 to R4 given, and typically integrated in an electronic valve V. These emitters E1 to E4 radiofrequency data of pressure of each wheel pi to P4 to 3. These pressure data are accompanied by an identifier code of the wheel IR1, IR2, IR3, IR4. The central unit 3 has the reception effect of these radio frequency signals a receiving antenna 7 which can also be used for receiving other types of signals such as a control signal for opening the doors of the vehicle. In addition, the central unit 3 comprises at least one processing means 9 for analyzing these pressure data P1 to P4 in order to determine whether the pressure of each tire is normal or not. For this, the central unit 3 can implement a comparison of the measured pressure value with a minimum pressure threshold. If the pressure is abnormal, the central unit 3 can generate an alarm signal intended for the user of the vehicle. Alternatively, the CPU 3 may also only display the pressure value read. The CPU 3 may further include a correct or incorrectly correct pressure binary signal display module, the binary signal itself being received as such from the wheel transmitter E1 to E4. BRT0489 AFR0634 Furthermore, in order to identify the wheel position corresponding to each identifier code IR1 to IR4, a location device is provided. This locating device comprises on each wheel R1 to R4: at least one wheel parameter sensor 5, for example in the valve 5 V or in the tire structure of the wheel R1, R2, R3, R4, these raised parameters allowing to determine the displacement and the direction of rotation of the wheel, - a calculator 11 establishing from these parameters a displacement indicator value and a direction of rotation, and a radiofrequency transmitter El to E4 transmitting this information to the central unit 3, for example at a predetermined time such as stopping the vehicle or when the vehicle has traveled a certain distance. It can be provided that the parameter sensor 5 is integrated with the transmitter E1, E2, E3, E4. As noted in FIG. 1, the emitter E1, E2, E3, E4 is the pressure data transmitter previously described. Similarly, the wheel parameter sensor 5 can also read pressure data P 1 to P 4 and form the pressure sensor 5 as previously described. For example, the parameter sensor 5 comprises an accelerometer, known per se, to know the direction of rotation and furthermore to know the displacement of a wheel R1, R2, R3, R4. Of course, it is possible to envisage any other sensor delivering a signal making it possible to determine the displacement and the direction of rotation of the wheel R1, R2, R3, R4. The accelerometer delivers a periodic acceleration signal. The periodicity of this acceleration, whether measured tangentially or radially to the wheel, is due essentially to the presence of the gravity vector. The periodic signal, here a sinusoid, can also be a square signal or even a pulse train, each of which is obtained for example for a given angular position of the wheel. The periodicity of the periodic signal processed by the computer 11 may be due to a periodicity of information such as generated by the sensor itself, as BRT0489 AFR0634 is the case for an acceleration measurement which is periodic by the the very existence of earthly gravity. This periodicity may also be due to a periodic deformation of the signal generated by the sensor, for example a deformation due to a lateral displacement of the sensor due to the deformation of the tire, or to a disturbance of the sensor output signal due to the proximity from the surface of the road to each wheel revolution. In addition, the periodic signal processed by the computer may alternatively include different periodic components, which may be periodic signals by the nature of the measurement and / or periodic signals by signal deformation.

The computer 11, which can also be integrated into the transmitter E1, E2, E3, E4, analyzes the periodic signal and delivers therefrom a digital value indicative of the displacement carried out by the wheel D1, D2, D3, D4, and information indicating the direction of rotation of the wheel S1, S2, S3, S4. The information indicating the direction of rotation is obtained by the sign of the acceleration value measured in the case of a tangential accelerometer, i.e. measuring a tangential acceleration on the wheel. This sign of the acceleration value, used here within the wheel, can also be used in the central computer of the vehicle. The information indicating the direction of rotation can also be obtained by analyzing a value of radial acceleration of the wheel, and operation within the wheel or centrally to the vehicle. For the calculation of the displacement carried out by the wheel, the computer here embarked on the wheel but which can also be central to the vehicle in the context of the invention, for example counts the number of periods or turns of wheels for a period of 25 minutes. observation given by counting the periods of the periodic signal during this observation period, for example for 30 seconds, a few minutes or even a few hours and deduces the value of the displacement of each wheel made over this period by multiplying the number of turns by the theoretical circumference of the wheel, possibly weighted by a coefficient dependent on the tire pressure measured at the instant in question by means of the pressure sensor. The transmitter embedded in the wheel BRT0489 AFR0634 then emits this value, or any other numerical value correlated thereto to the central computer so that the latter then discriminates front / rear of the different wheels. In another embodiment, the displacement calculation is performed by a computer on board the wheel or in a computer on the véchiule, as follows. The tangential acceleration values are measured at successive moments sufficiently close to allow integration of these acceleration values in the computer. The result of this integration is the speed at the given moment of the vehicle. The computer furthermore achieves an integration of the speed value thus obtained at each moment since the vehicle is set in motion, and obtains by this second integration a value of the distance traveled since the setting in motion. According to yet another method of calculating the displacement, the speed is measured at each instant by measuring a centrifugal acceleration delivered by a radial acceleration sensor. One calculates then by a simple integration, again in local or in central, the displacement carried out by the wheel since the setting in movement of the vehicle. An observation time of 30 seconds proves particularly advantageous because it combines a precision close to the optimum for a short enough time to avoid too long calculation periods and which would hinder the continuity of the information delivered to the driver, especially during the initial or transitory calculation phases where the location is in progress and not yet established. The fact of calculating the displacement carried out within the wheel itself makes it possible to release the central computer from the work of analyzing the behavior of the wheel through, for example, the analysis of the periodic or pulsed signal, and makes it possible, by the fact of transmitting a result of this analysis in the form of a numerical value that indicates the displacement made, to reduce the volume and the complexity of the transmitted data. The simplification of the data transmitted to the central computer also makes it possible to overcome communication difficulties between the valve and the central computer, and makes such a localized analysis valve particularly adaptable to different vehicles having variable central calculators. The central unit 3 comprises in turn at least one comparator 9 of the direction of rotation information S1 to S4 so as firstly to discriminate the left wheels RI, R3 of the right wheels R2, R4 as a function of the comparison results. .

The comparator 9 then compares the displacement values D1, D3 of the two left wheels R1, R3 for example, and the central unit 3 determines that the wheel having the highest displacement value is the directional wheel (here the front wheel R1 ). Similarly, the comparator compares the displacement values D2, D4 of the two right-hand wheels R2, R4, and the central unit 3 determines that the wheel having the higher displacement value is the directional wheel (here the front wheel R2). . Thus, with reference to FIGS. 1 and 2, a locating method implemented by such a locating device comprises the following steps: each accelerometer of a wheel R1, R2, R3, R4 transmits a periodic signal to a computer 11 to calculate the displacement and determine the direction of rotation of each wheel R1, R2, R3, R4 in a first step E1, each emitter E1, E2, E3, E4 emits at step E2 by radiofrequency information indicative of the direction of rotation and displacement of the wheel Ri, R2, R3, R4 associated, in step E3, the central unit 3 receives this information and determines by correlating this information the position of the left wheels R1 and R3, of right R2 and R4, front R1 and R2, and rear R3 and R4. For example, the emitter El emits pressure information P1, displacement D1 and direction of rotation S1 with an identifier code IR1, the emitter E2 transmits pressure information P2, displacement D2 and direction of rotation S2 with An identifier code IR2, the emitter E3 transmits pressure information P3, displacement D3 and direction of rotation S3 with an identifier code IR3, and the emitter E4 transmits pressure information P4, displacement D4 and direction rotation S4 with an identifier code IR4. After reception by the antenna 7, the central unit 3 analyzes the information of the direction of rotation S1 to S4, the directions of rotation S1 and S3 being substantially identical BRT0489 AFR0634 the central unit 3 determines that the identifier codes IR1 and IR3 are associated with the left wheels R1 and R3, and the rotation directions S2 and S4 are substantially identical the central unit 3 determines that the identifier codes IR2 and IR4 are associated with the right wheels R2 and R4.

The left / right discrimination being made, the CPU 3 compares the displacement data associated with the sensors 5 located on the wheels on the same side. Thus, the central unit 3 compares on the one hand the displacement data D1 and D3, and on the other hand the displacement data D2 and D4. The displacement data DI indicating a greater distance traveled relative to D3, the central unit 3 determines that the identifier code IR1 is associated with the left front wheel R1 and that the identifier code IR3 is associated with the left rear wheel R3. Similarly, the displacement data D2 indicating a greater distance traveled relative to D4, the central unit 3 determines that the identifier code IR2 is associated with the right front wheel R2 and that the identifier code IR4 is associated with the rear wheel right R4.

According to the embodiment, it is possible firstly to carry out a left-right discrimination and then a front-to-back discrimination, or firstly a front-to-back discrimination and then a left-right discrimination, or both at the same time by bringing the information into a table of contents. crossing of the data. Similarly, the left right discrimination has here been described as realized by determining the direction of rotation of the wheel. The left-hand side can be determined in other ways, for example by pre-registration on the side of the wheel in association with its identifier code in a central memory of the vehicle when mounting the wheel on the vehicle, or by mounting valves dedicated to a right side respectively left and having an identifying code indicating whether the valve is a valve dedicated to the right side or a valve dedicated to the left side. It is advantageous to first discriminate the side wheels, i.e. the right wheels of the left wheels. Then within a given pair of side wheels, for example the left wheels, it discriminates the front wheel of the rear wheel by the fact that the front wheel is the first to reach the pre-established distance.

This embodiment allows a faster overall location. Indeed, BRT0489 AFR0634 in the particular case where a vehicle makes a straight-curved trip for example, then there is a tick that the two left wheels perform a greater distance to the two straight wheels. By making a preliminary selection of the left wheels and the right wheels, and by discriminating inside these couples, one thus avoids these dominances of curvature. According to the embodiment described, the central unit 3 receives displacement information and direction of rotation calculated and / or determined at the wheels of the vehicle; it can be provided according to an alternative that the central unit 3 receives information calculated by a system external to the wheels of the vehicle, such as an anti-locking wheel "ABS" for the German "Antiblockiersystem" or a system of correction of "Electronic Stability Program" (ESP) trajectory allowing the central unit to locate the left / right and front / rear wheels. Likewise, a system has been described in which the displacement indicator value is calculated in a manner embedded in the wheel. According to an alternative, the displacement indicator value of a given wheel is calculated in the central computer of the vehicle, remote from the wheel, for example by analysis of a periodic or impulse signal reflecting the wheel turns of the vehicle emitted by the wheel this analysis being performed for example in the manner described above, ie by counting wheel turns performed during a given observation period. The front / rear discrimination can be implemented automatically at each start. As soon as the position of the wheels is acquired, the localization process is interrupted. As a variant, the front / rear discrimination can be implemented when the vehicle has already traveled a predefined distance or after a time delay. This ensures that there has been a minimum of turns to discriminate the front and rear wheels. Reset of the locating process may be provided at each stop of the vehicle.

This resetting may consist of a new calculation of determination of the location of the wheels, preferably after a complete stopping of the vehicle including the stopping of the engine and accessories of the vehicle. This reset may also consist of a reset of the current wheel displacement measurements, whether these measurements are calculated within the wheels or at the central level of the vehicle. Such a reset is preferably triggered when the valves identify a lack of movement of the vehicle for a period exceeding a predetermined time threshold, for example a few minutes. It can be further provided that such a locating method is implemented for example at each wheel change, on the user's command or automatically when the central unit 3 detects a new identifier code when transmitting the data. pressure information. It will therefore be understood that with such a locating method and the corresponding locating device, in particular associated with a tire pressure monitoring system of a vehicle, it is possible to simply identify the position of the sensors on the vehicle without requiring complicated and reliable electronics even when changing tires. In the embodiments described above, a distance traveled in a pre-established period of time is established to compare the distances thus established. In another embodiment of the invention, in order to calculate the distance traveled for each wheel, the crossing of a predetermined distance, for each wheel, by the distance calculated at a given time, for example the crossing of a given distance, is detected. pre-established distance of 500 meters or 200 wheel turns, and measured for each wheel, the duration taken by it to reach this pre-established distance. The calculation of the distance traveled by each wheel is then used to detect the fact that a given wheel has made the displacement necessary to allow effective discrimination between the behavior of the different wheels, here the speed with which each wheel will perform such a displacement sufficient , the front wheels reaching this displacement sufficient faster than the rear wheels. Several ways of exploiting the time thus measured are then possible within the scope of the invention. BRT0489 AFR0634 In a first embodiment, the front wheels are identified as those having reached the pre-established distance, the measurement of the time required to reach the pre-established distance is then no longer necessary for the other wheels. In a second particularly advantageous embodiment, the right wheels of the left wheels are discriminated first. Then within a given pair of side wheels, for example the left wheels, it discriminates the front wheel of the rear wheel by the fact that the front wheel is the first to reach the pre-established distance. This embodiment allows a faster overall location. Indeed, in the particular case where a vehicle makes a path dominated by straight curvature for example, then there is a risk that the two left wheels perform a greater distance to the two straight wheels. By making a preliminary selection of the left wheels and the right wheels, and discriminating inside these couples, one overcomes these dominances of curvature.

In a particularly advantageous embodiment in that it is inexpensive and simple to implement, the wheel carries a calculator which identifies the fact that the wheel has made a pre-set number of revolutions. The distance calculation performed here again consists of the count of the number of laps performed, which then constitutes the indicative distance traveled. When the crossing of the predetermined number of revolutions is identified as realized, the emitter of the wheel sends a signal to the central computer of the vehicle. The latter then takes into account that the given wheel has made the preset distance. Such a device is then preferably configured so that the count of the number of wheel turns performed within each computer starts each time the wheels of the vehicle are set in motion. Such initiation each time the vehicle is set in motion is easily implemented by adopting an inertia switch in the valve, or by a recurrent measurement of the radial or tangential acceleration in the wheel, the reccurence of the measurements. being close enough to identify the setting in motion. BRT0489 AFR0634 The fact that the count of the number of wheel turns performed within each computer starts each time the vehicle wheels are started makes the measurement more reliable because the different wheels will send their pre-set distance crossing signal at times different and it is necessary to ensure that the signals thus received at different times correspond to the same place of wheel turns for each wheel, ie that it is indeed the first 200 wheel turns for example, and not 200 wheel turns measured later for example. In order to make reliable the detection of the start-up, or to simplify the detection system of the start-up, the detection of the start-up of a wheel can consist in the identification of a certain number of preliminary turns to the measurement, for example 2 or 3 wheel revolutions. The equipment of each wheel preferably sends a first signal to indicate that it starts the counting of wheel turns. The existence of such a synchronization of the countdown to the setting in motion of the vehicle makes it possible to associate the measurements of time necessary for the first turns of wheel, 200 for example, but also makes it possible to associate two measurements of time necessary with subsequent turns of the wheel, such as the 200 laps of wheels made after the first 200 laps, or such as the 200 laps of wheels made on a beach overlapping the first beach in the case where one carries out a sliding average of the time required to complete the pre-set number of laps. In these different cases, the starting synchronization can also reliably associate these subsequent measurement ranges, again without the need for a clock on the wheel. BRT0489 AFR0634

Claims (12)

REVENDICATIONS1. Method for locating the wheels (R1, R2, R3, R4) of a motor vehicle, characterized in that it comprises the following steps: a data item indicative of a displacement of each wheel (D 1, D 2, D 3 , D4), a left / right side is determined on which each wheel (S1, S2, S3, S4) is located, a front wheel of a rear wheel is discriminated according to comparison results because of the fact that a directional front wheel travels a distance greater than a rear wheel for a given duration, a wheel is located by combining the displacement information (D1, D2, D3, D4) and the left / right side (S1, S2, S3, S4) of the wheel. 2. A locating method according to claim 1, characterized in that it comprises the following steps: we locate the left wheels (R1, R3) and the right wheels (R2, R4) according to information indicative of the direction of rotation of each wheel (S1, S2, S3, S4), we compare the information indicative of displacement (D1, D2, D3, D4) of the wheels located on the left (R1, R3) on the one hand, and localized wheels on the right (R2, R4) on the other hand, for each left and right side, the directional front wheel is identified according to the comparison results because the directional front wheel travels a greater distance than the rear wheel of the same side. 3. The locating method according to one of claims 1 or 2, characterized in that it comprises a reset at each stop of said vehicle. 4. Location method according to any one of the preceding claims, characterized in that: - the data indicative of a displacement of a wheel (D1, D2, D3, D4) is compared with a pre-established indicative threshold value. The time taken by the wheel to reach said predetermined value indicative of displacement is measured by measuring the time taken by the wheel. This wheel is discriminated as being a directional front wheel or a rear wheel as a function of the duration thus measured. 5. Location method according to the preceding claim, characterized in that it comprises the following steps: - one locates the left wheels (R1, R3) and the right wheels (R2, R4) according to information indicative of the direction of rotation of each wheel (S1, S2, S3, S4), - for each left and right side, the directional front wheel is identified among the left or right wheels according to the comparison results because the directional front wheel is traveling the pre-set distance for a shorter time than the rear wheel on the same side. 6. Location method according to any one of the preceding claims, characterized in that it is implemented at each start of said vehicle. 7. Device for locating the wheels of a motor vehicle, characterized in that it comprises on each wheel (R1, R2, R3, R4) at least one sensor (5) of wheel parameters, on each wheel at least a calculator (11) establishing a value indicative of a displacement (D1, D2, D3, D4) effected by the wheel from said sensed parameters of the wheel, and, on each wheel, a transmitter (E1, E2, E3, E4) of radiofrequency signals for outputting said displacement indicator value (D 1, D 2, D 3, D 4). 8. Device according to the preceding claim, characterized in that it comprises on each wheel a sensor (5) of wheel parameters and on each wheel at least one computer (11) establishing from said sensed parameters information of direction of rotation (S1, S2, S3, S4) of the wheel, the device further comprising a central unit (3) configured to receive the rotational direction indicator information (S1, S2, S3, S4) and the indicator value of the displacement (D1, D2, D3, D4) transmitted from each wheel and for locating each of the wheels in BRT0489 AFR0634combining said information indicating direction of rotation (S1, S2, S3, S4) and said displacement indicator values (D1, D2, D3, D4) received. 9. Locating device according to claim 7 or claim 8, characterized in that said sensor (5) comprises an accelerometer configured to deliver a periodic signal. 10. Location device according to the preceding claim, characterized in that the periodic signal delivered is a sinusoidal acceleration signal. 11. Locating device according to any one of claims 7 to 10, characterized in that said sensor (5) and the transmitter (EI, E2, E3, E4) are integrated in the valve (V) of the wheel ( R1, R2, R3, R4). 12. Tire pressure monitoring system of a motor vehicle, comprising on each wheel of the vehicle a pressure sensor (5) and an emitter (E1, E2, E3, E4) of radiofrequency signals for transmitting a pressure indication ( P1, P2, P3, P4) and a wheel identifier (IR1, IR2, IR3, IR4) to a central unit (3) of said vehicle, characterized in that it further comprises a device for locating the wheels according to the any of claims 7 to 11. BRT0489 AFR0634