Method for reading information contained in an RFID chip embedded in a vehicle tire

Abstract

The invention relates to a method for reading information contained in an RFID chip embedded in the tire of a motor vehicle wheel equipped with a wheel unit (11) forming part of a tire pressure monitoring system. The method involves detecting, by means of the wheel unit (11), regardless of the wheel's condition (punctured or not), a wheel removal operation followed by the inflation of the new tire. The RFID chip is then interrogated by means of the wheel unit (11) when the inflation operation has been detected. Figure 1

Description

Title of the invention: Method for reading information contained in an RFID chip embedded in a vehicle tire

[0001] The present invention relates to the field of electronic monitoring of the characteristics of tires of motor vehicles.

[0002] As is known in itself, the characteristics (origin, technical data...) of a motor vehicle tire can be stored inside an RFID chip embedded in the mass of the tire.

[0003] “RFID” is an English acronym meaning “Radio Frequency Identification”.

[0004] An RFID chip can receive and respond to radio requests emitted by an external transmitter / receiver, without contact.

[0005] By using a suitable manual reading tool that is brought close to the tire, the information contained in the RFID chip can be accessed, through an exchange of requests / responses between the reading tool and the chip.

[0006] The information thus retrieved in the reading tool can subsequently be sent in particular to the memory of an electronic module fixed on the rim on which the tire is mounted, such a module being commonly referred to as a "wheel unit", and being part of a "TPMS" (Tire Pressure Monitoring System) type system allowing monitoring in particular of the tire pressure.

[0007] Manual reading of RFID chips housed inside tires is tedious, and there is a real need to automate it.

[0008] The present invention aims in particular to meet this need.

[0009] This objective of the invention, as well as other advantages, is achieved with a method of reading information contained in an RFID chip embedded in the mass of a tire of a wheel of a motor vehicle equipped with a wheel unit forming part of a vehicle tire pressure monitoring system (TPMS), in which a wheel removal operation is detected by means of the wheel unit, followed by a tire inflation operation, and the RFID chip is interrogated by means of the wheel unit when the inflation operation has been detected.

[0010] Thanks to these characteristics, the retrieval of information stored in the RFID chip can be done automatically by the wheel unit following a wheel dismantling operation followed by a tire reinflation operation, these operations being characteristic of a tire change.

[0011] This one-off communication between the wheel unit and the RFID chip only takes place, thanks to the method according to the invention, during an actual tire change, We avoid any other communication that would have the effect of reducing the autonomy of the electric battery housed inside the wheel unit.

[0012] Typically, such one-off communication only takes place two or three times during the lifetime of the tire, in order to minimize the impact on the electric battery.

[0013] According to other optional features of the present invention, taken alone or in combination:

[0014] - the wheel removal operation is detected by taking into account variations pressure measured by the vehicle's wheel units which are representative of a vehicle lifting operation: these pressure variations provide an indirect and simple means of detecting a lifting operation;

[0015] - according to a first variant of the method according to the invention, applicable to the case of a Flat tire needs changing: - a) a wheel unit emits a signal indicating that one of the vehicle's tires has punctured, then - b) at least one of the other wheel units emits signals indicating that the vehicle is being lifted, then - c) the wheel unit associated with the punctured tire detects a variation or gradient of acceleration lower than that of normal vehicle motion when moving on the ground, then The wheel unit associated with the punctured tire receives a signal indicating that this tire is being changed and monitors the moment when the measured pressure will rise sharply: the combination of conditions a), b), c) makes it possible to establish with certainty that the vehicle whose tire is punctured is indeed in a situation of dismantling the wheel containing this tire;

[0016] - according to a second variant of the method according to the invention, applicable to the case of a Worn tire needs replacing: - a) at least one of the vehicle's wheel units emits signals indicating that the vehicle is being lifted, then - b) a wheel unit emits a signal indicating that one of the vehicle's tires is underinflated, then The wheel unit associated with the deflated tire monitors the moment when the measured pressure will rise sharply: the combination of these conditions makes it possible to establish with certainty that the vehicle whose tire is worn is indeed in a situation of dismantling the wheel containing this tire;

[0017] - the wheel unit associated with the deflated tire detects a variation or gradient accelerations lower than those of normal vehicle movement when moving on the ground;

[0018] - when said wheel unit is equipped with an accelerometer enabling the measurement of movements along a direction parallel to the wheel axis, the operation of removing said wheel is detected by measuring this acceleration: this solution provides a very simple alternative to the detection of pressure variations during a lifting of the vehicle, mentioned above;

[0019] - when the wheel units of the vehicle are equipped with means for evaluating By accurately measuring the distances of these units relative to each other, the operation of removing said wheel is detected by measuring the change in distance of said wheel unit relative to the others: this solution provides another very simple alternative to the detection of pressure variations during a vehicle lift, mentioned above.

[0020] The present invention also relates to a motor vehicle wheel equipped with a wheel unit forming part of a TPMS system and a tire containing an RFID chip, this wheel unit and this RFID chip being configured to communicate with each other according to a method in accordance with the above.

[0021] The present invention also relates to a motor vehicle equipped with a TPMS system and comprising at least two wheels conforming to the above.

[0022] Other features and advantages of the invention will become apparent from the following description, with reference to [Fig.1] which illustrates an example of an assembly comprising a motor vehicle tire valve equipped with a wheel unit forming part of a TPMS type system.

[0023] This figure shows an inflation valve 1 of a motor vehicle tire, comprising a body 3 surmounted by a closing cap 5.

[0024] The body 3 comprises a tubular metal part, the end 7 of which opposite the cap 5 is visible in [Fig.1], this tubular metal part being coated with a flexible material such as synthetic rubber.

[0025] This flexible coating has a groove or shoulder 9 to ensure that the valve is held inside an opening formed in a wheel rim of a motor vehicle (not shown): this is referred to as a "snap-in" type valve.

[0026] The end 7 of the tubular metal part visible in [Fig.1] is intended to open into the chamber defined by the rim and the tire of the motor vehicle, so as to allow the introduction or exit of air to and from this chamber.

[0027] A sensor assembly 11 - usually called a "wheel unit" - is fixed to the valve 3, for example at the end of the tubular metal part 7.

[0028] As is known in itself, this wheel unit 11 comprises a pressure sensor inside the chamber defined by the rim and the tire, as well as an accelerometer, a temperature sensor, and means for communication with the an on-board electronic control unit (often referred to as an "ECU") of a motor vehicle, and a battery to power the assembly. Such a wheel unit 11 can also be attached to a valve of a different type than the "snap-in" valve described above, such as, for example, a metal valve known per se, or be directly attached to a wheel rim, or be fixed to the inner face of a tire tread.

[0029] Within the framework of the present invention, the communication means of the wheel unit 11 are also adapted to communicate with an RFID chip embedded in the tire mounted on the rim of the wheel.

[0030] Typically, this communication can take place on a low frequency band of approximately 125 kHz.

[0031] According to a first scenario corresponding to the case of a tire that has punctured, the wheel unit 11 detects this puncture which is expressed by a drop in air pressure inside the tire.

[0032] It is then necessary to change this tire, which requires lifting the vehicle, which can be done either on a spot basis at the tire that has punctured, using a jack, or globally with a lifting bridge that lifts the entire vehicle.

[0033] In the case of the occasional lifting of the vehicle by means of a jack, it was observed that the tire located diagonally to the one that punctured (for example, the left rear tire if it was the right front tire that punctured), was found to be slightly over-pressurized - typically on the order of an additional IkPa - due to the transfer of the weight of the vehicle.

[0034] In the case of the overall lifting of the vehicle using a lifting bridge, it was observed that the 2 or 3 tires that had not punctured were found to be slightly under-pressure - typically on the order of 2kPa less than their pressure when the vehicle is resting on the ground.

[0035] This tire pressure information is transmitted by the wheel units of each wheel to the ECU of the motor vehicle.

[0036] When the ECU receives the following information from the wheel units: - a) signal from a wheel unit indicating that one of the tires has punctured, then - b) signals from at least one of the other wheel units indicating that the vehicle is being lifted (by comparing pressures as described above) and that the wheel unit associated with the flat tire detects a variation or gradient of acceleration lower than that of normal vehicle movement when moving on the ground - these movements therefore being indicative of a wheel change operation, then the ECU sends a signal to the wheel unit associated with the punctured tire indicating that this tire is being changed and that it is necessary to monitor - continuously but with periodic pressure acquisitions - the moment when the measured pressure will rise sharply.

[0037] This increase in pressure corresponds to the reinflation of the tire which will have been mounted on the rim of the wheel, in replacement of the punctured tire.

[0038] When the wheel unit detects this increase in pressure, it establishes a one-time communication with the RFID chip which is embedded in the mass of the new tire, allowing the information stored in this chip to be retrieved, characterizing the new tire.

[0039] This information may relate, for example, to the origin of the tire, as well as a number of technical characteristics (width and thickness of the tread, nature of the material forming this tread, etc.).

[0040] All this information can be sent by the wheel unit to the vehicle's ECU, which can then use it for example for navigation assistance purposes, or for predicting the level of tire wear.

[0041] This information can also be transmitted by the ECU to servers located outside the vehicle, for centralized processing.

[0042] As will be understood from the above, the RFID chip embedded in the mass of the tire is only activated by the wheel unit when the tire is changed, following a puncture.

[0043] This single request allows the information contained in the RFID chip to be retrieved automatically with minimal consumption of the electrical energy from the wheel unit's battery.

[0044] As an alternative to what has just been described, the information on tire pressure variation corresponding to lifting operations could be transmitted directly between the wheel units, without going through the ECU, provided that the latter has previously put these wheel units into contact.

[0045] According to a second scenario, corresponding to the case of a worn tire to be replaced, steps a) and b) mentioned in the first scenario are reversed, that is to say that we start by detecting a situation of lifting the vehicle, then a situation of strong pressure drop in one of the tires (but not a puncture) corresponding to the deflation of the worn tire in view of its replacement.

[0046] The final step is identical, that is to say that communication is established between the wheel unit and the new tire only when the latter has been reinflated.

[0047] As an alternative to the method just described, and in the case where the wheel unit includes an accelerometer for measuring displacements along a parallel direction at the wheel axle, we can consider replacing steps a) to c) of the first and second scenarios with a measurement of this acceleration, allowing us to characterize a wheel dismantling operation, and therefore a replacement of a punctured or worn tire.

[0048] According to yet another possible variant, and in the case where the wheel units are provided with means allowing to accurately evaluate the distances of these units to each other - such as for example Channel Sounding means offered by Bluetooth® technology - it is possible to consider replacing steps a) to c) of the first and second scenarios with a measurement of the variation in distance of a wheel unit to the others, allowing to characterize an operation of dismantling the wheel, and therefore a replacement of a punctured or worn tire.

[0049] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

Claims

Demands

1. A method for reading information contained in an RFID chip embedded in the mass of a tire of a wheel of a motor vehicle equipped with a wheel unit (11) forming part of a vehicle tire pressure monitoring system, wherein a wheel removal operation is detected by means of the wheel unit (11), followed by a tire inflation operation, and the RFID chip is interrogated by means of the wheel unit (11) when the inflation operation has been detected.

2. A method according to claim 1, wherein the wheel removal operation is detected by taking into account pressure variations measured by the vehicle's wheel units which are representative of a vehicle lifting operation.

3. A method according to claim 2, wherein: - a) a wheel unit (11) emits a signal indicating that one of the vehicle's tires has punctured, then - b) at least one of the other wheel units emits signals indicating that the vehicle is being lifted, then - c) the wheel unit (11) associated with the punctured tire detects a variation or gradient of acceleration lower than that of normal movement of the vehicle when moving on the ground, then the wheel unit (11) associated with the punctured tire receives a signal indicating that this tire is being changed and monitors the moment when the measured pressure will rise sharply.

4. Method according to claim 2, wherein: - a) at least one of the vehicle's wheel units emits signals indicating that the vehicle is being lifted, then - b) a wheel unit (11) emits a signal indicating that one of the vehicle's tires is being deflated, then the wheel unit (11) associated with the deflated tire monitors the moment when the measured pressure will rise sharply.

5. A method according to claim 4, wherein the wheel unit (11) associated with the deflated tire detects a variation or gradient of acceleration lower than those of normal vehicle motion when moving on the ground.

6. A method according to claim 2 wherein, when said wheel unit (11) is equipped with an accelerometer for measuring movements along a direction parallel to the wheel axis, the operation of dismantling said wheel is detected by a measurement of this acceleration.

7. A method according to claim 2 wherein, when the wheel units of the vehicle are provided with means for accurately evaluating the distances of these units to each other, the operation of removing said wheel is detected by measuring the change in distance of said wheel unit (11) to the others.

8. A motor vehicle wheel equipped with a wheel unit (11) forming part of a tire pressure monitoring system and a tire containing an RFID chip, this wheel unit (11) and this RFID chip being configured to communicate with each other according to a method in accordance with any one of the preceding claims.

9. Motor vehicle equipped with a tire pressure monitoring system and comprising at least two wheels conforming to claim 8.