Method for monitoring the wear of a motor vehicle tire and tire pressure monitoring module for implementing said method

Abstract

Method for monitoring the wear of a motor vehicle tire and tire pressure monitoring module for implementing said method. The invention relates to a method for monitoring the wear of a motor vehicle tire. According to the invention, the method comprises the following steps aimed at: - acquiring (step E1), from a tangential acceleration signal of said monitoring module, measurements of a variable included in the group comprising a maximum peak of tangential acceleration and a minimum peak of tangential acceleration, - processing (step E2) said measurements of said acquired variable, - comparing (step E3) said processed measurements to a predetermined threshold value of maximum variation, - issuing an alert (step E4) when said predetermined threshold value of maximum variation is reached.The invention also relates to a tire pressure monitoring module for implementing said method. Figure for the abstract: Figure 4.

Description

Title of the invention: Method for monitoring the wear of a motor vehicle tire and tire pressure monitoring module for implementing said method Technical field

[0001] The present invention relates to a method for monitoring the wear of a motor vehicle tire and a tire pressure monitoring module for implementing said method. Prior art

[0002] Conventionally, the tire has at its outer surface a zone called “tread”, corresponding to the outer surface of the tire which is in contact with the road.

[0003] The tread includes a relief, also called a "sculpture", which allows in particular the evacuation of rainwater, snow, dust and heat, in order to limit the loss of grip of the tire or to avoid aquaplaning.

[0004] As the vehicle travels, the tire's tread wears down and becomes smooth, increasing the risk of loss of grip. Therefore, once the vehicle reaches a certain level of wear, it is necessary to replace the worn tire with a new one.

[0005] In order to detect the wear of a tire, it is known to use methods for monitoring the state of wear of the tire.

[0006] A first type of method, called “direct methods”, makes it possible to deduce the deterioration of the tire through the use of a device which wears at the same time as the tire wears.

[0007] These methods can be manual, by means of a colored wear strip integrated into the tread. This solution is however unsatisfactory insofar as the vehicle owner must visually check his tire in order to determine whether it needs to be replaced. Also, he must think about checking his tires himself. However, a person of average attention does not check his tires systematically and risks traveling, after a certain time, on board a vehicle equipped with worn tires offering little grip, which presents a clear danger.

[0008] Also, there is a growing need to autonomously monitor the wear of a tire, particularly in the context of vehicle fleet management, a model which is part of the growing development of new modes of mobility for which the driver is not the owner and where monitoring and maintenance are carried out by specific organizations on large sets of vehicles. Also, autonomous monitoring of tire wear applies even more to autonomously driven vehicles.

[0009] Among the autonomous methods for monitoring tire wear, direct methods are also known, making it possible to deduce the deterioration of the tire and in particular implemented by measuring variations in the impedance of tubes which pass through the tire.

[0010] A second type of method, called “indirect methods”, makes it possible to deduce a state of wear of the tire by exploiting data from one or more parameters of the wheel or the motor vehicle.

[0011] Among the indirect methods of automatic monitoring of tire wear, there is a method known under the name "TDM", an English acronym for "Thread Depth Monitoring".

[0012] This method mainly uses signals from the systems embedded in the motor vehicle to deduce the state of wear of the tires.

[0013] These on-board systems include, in particular: - a positioning system, known as “GPS”, the English acronym for “Global Positioning System”, which enables the speed of the motor vehicle to be acquired, - a wheel speed sensor, known as “WSS”, the English acronym for “Wheel Speed ​​Sensor”, and used to acquire the rotation speed of the wheels of the motor vehicle, - a tire pressure monitoring module, known as “TPMS”, the English acronym for “Tire Pressure Monitoring System”, which allows the tire pressure to be acquired.

[0014] Among the indirect methods for automatically monitoring tire wear, there is also known a method known under the name "TDS", an English acronym for "Thread Depth Sensing", which aims to exploit more directly a signal which is perceived by the TPMS module and by which the state of wear of the tires will be drawn almost exclusively from this signal.

[0015] Unlike the aforementioned so-called “TDM” method, where a set of information acquired by different sensors of the motor vehicle is compiled, the so-called “TDS” method is applied as close as possible to the source of the parameter that one wishes to monitor, which makes it possible to reduce the chain of causality used to deduce a state of wear of the tires of the motor vehicle.

[0016] Thus, thanks to the so-called “TDS” method, the chain of causality is much shorter and is thus more precise than that obtained by the so-called “TDM” method.

[0017] A “TDS” method known from the prior art consists of exploiting the signal tangential acceleration in the contact zone of the tire with the ground, to deduce a state of wear of the tire.

[0018] This signal corresponds to the tangential acceleration signal seen by the TPMS module which is mounted in the tire and which is fixed at the level of the tire tread.

[0019] The tangential accelerometer of the TPMS module tracks the tangential acceleration during rotation of the wheel on which the tire to be monitored is mounted.

[0020] Currently, the data acquired by the TPMS module is transmitted by radio frequency to a central computing unit comprising a centralized electronic calculator known as “ECU”, an English acronym for “Electronic Control Unit”).

[0021] The centralized electronic calculator will, from the acquired data, develop a transfer function in order to determine a tire thickness from the acquired tangential acceleration signal.

[0022] Communication between the TPMS module and the central unit computer is relatively complex to implement.

[0023] Indeed, the communication between the TPMS module which acquires the data and the computer of the central unit which processes the data requires a pairing phase of the TPMS module and the computer of the central unit.

[0024] Also, a communication strategy between the TPMS module and the central unit computer must be specifically developed to enable this communication.

[0025] Furthermore, a solution aimed at migrating the architecture allowing the calculation directly into the TPMS module would not be easy to implement because certain data is accessible only by the centralized computer and not by the TPMS module. Statement of the invention

[0026] The present invention aims to overcome the drawbacks of the prior art, and to do so relates to a method for monitoring the wear of a motor vehicle tire, implemented by a tire pressure monitoring module mounted in said tire to be monitored, said module comprising a pressure sensor and a tangential accelerometer, said method being remarkable in that it comprises the following steps aimed at: - acquiring (step E1), from a tangential acceleration signal of said tire pressure monitoring module, measurements of at least one variable included in the group comprising a maximum tangential acceleration peak and a minimum tangential acceleration peak, - carry out (step E2) a processing of said measurements of said at least one acquired variable, - compare (step E3) said processed measurements with a predetermined threshold value of maximum variation, - issue an alert (step E4) when said predetermined maximum variation threshold value is reached.

[0027] Thanks to the present invention, a solution is obtained for monitoring tire wear carried out solely by the tire pressure monitoring module mounted in the tire to be monitored, which makes said solution autonomous and easily operational.

[0028] No particular system integration is then necessary. The fact that the method according to the invention is implemented by a tire pressure monitoring module mounted in the tire to be supervised makes it possible to avoid having to transmit information to the centralized computer of the central computing unit of the motor vehicle, which in particular has a direct influence on the energy consumption and the lifespan of the monitoring module.

[0029] Also, the information can be used in a more direct manner compared to the prior art, and therefore more efficiently. The tire pressure monitoring module thus provides more refined information, which makes it possible to increase the relevance of developing a wear treatment strategy.

[0030] The supervision method according to the invention makes it possible to monitor and process the tangential acceleration signal from the tire pressure monitoring module, making it possible to deduce therefrom a significant level of wear which will make it possible to issue an alert if necessary.

[0031] Thus, unlike the known solutions of the prior art, no transfer function is used to determine from the acquired tangential acceleration signal a consumed thickness of the tire tread.

[0032] According to optional characteristics of the method according to the invention: - said acquisition step (step El) comprises a sub-step (step Eli) of learning initial conditions aimed at determining a reference value of said at least one variable V; - said reference value Vref of said at least one variable V is equal to the average of the values ​​of said at least one variable V measured over a predetermined number of kilometers traveled by the supervised tire; - said acquisition step (step El) comprises a sub-step (step E12) subsequent to said sub-step (step Eli) of learning initial conditions and comprising the acquisition of measurements of instantaneous variables V(t) or the acquisition of an average value Vfn^ equal to the average of the values ​​of consecutive measurements of said at least one variable V over a predetermined number of kilometers traveled by the supervised tire; - said processing step (step E2) of said measurements of said at least one variable V acquired during the acquisition step (step E1) is carried out by applying an identity function on the basis of which a value equal to the difference in absolute value between one of said instantaneous variables V(t) and said reference value Vref, or the difference in absolute value between said average value Vy(7Z(f) and said reference value Vref is calculated; - the method comprises a step aimed at predicting (step E5) the remaining mileage before reaching a predetermined level of wear of the supervised tire; - said step aimed at predicting (step E5) the remaining mileage before reaching a predetermined wear level of the supervised tire is implemented following the alert emission step (step E4); - said step aiming at predicting (step E5) the remaining mileage before reaching a predetermined wear level of the supervised tire is implemented before reaching the alert emission step (step E4); - said acquisition step (step E1) is carried out by periodically measuring said at least one variable V for an iteration i and for an iteration ik, k>0, each of said iterations being carried out over a predetermined kilometer window; - said processing step (step E2) deduces, from the measurements acquired during the acquisition step (step E1) an average value of said at least one variable Vmoy followed on iteration i, representative of the average of the measurements of said at least one variable Vmoy followed on iteration i, at least one variable V for an iteration i, and an average value of said variable Vmoy,k, k>0, representative of the average of the measurements of said at least one variable V for an iteration ik; - said processing step (step E2) is carried out by applying a derivative function on the basis of which a value derived from the average values ​​of said at least one variable V is calculated, equal to the difference in absolute value between the derivative with respect to time of the average value of said at least one variable Vmoy. on iteration i and the derivative with respect to time of the average value of said at least one variable Vmoy., on iteration ik, k>0; - said acquisition step (step E1) can be initiated after a predetermined number of kilometers has been traveled by said tire to be supervised; - according to one provision, said at least one variable V is a compensated value.

[0033] The invention also relates to a tire pressure monitoring module, comprising hardware and / or software means for implementing the method according to the invention, remarkable in that said hardware and / or software means are implemented in an integrated circuit. Brief description of the drawings

[0034] Other characteristics, aims and advantages of the invention will appear on reading the detailed description which follows, for the understanding of which reference will be made to the appended drawings in which:

[0035] [Fig-1] is a schematic view of a tire of a wheel of a vehicle at car according to the invention.

[0036] [Fig.2] shows a curve illustrating an example of a tangential acceleration signal Z of a tire pressure monitoring module to be monitored over time?

[0037] [Fig.3] shows a comparison of tangential acceleration signals of a first pneumatic and a second pneumatic.

[0038] [Fig.4] details the steps of the process for monitoring the wear of a tire of motor vehicle according to the invention.

[0039] [Fig.5] details the steps of the supervision process according to a first mode of rea lization of the invention.

[0040] [Fig.6] shows the implementation of one of the steps of the method according to the first embodiment of the invention.

[0041] [Fig.7] shows an alternative embodiment of the first embodiment. Description of the embodiments

[0042] In the remainder of the description, elements having an identical structure or similar functions are designated by the same reference.

[0043] Reference is made to [Fig.l] which illustrates a tire 1 of a wheel of a motor vehicle according to the invention.

[0044] The tire 1, mounted in a motor vehicle wheel (not shown) rests on a ground 3.

[0045] The tire 1 has a nominal radius Rn defined by the radius of the tire 1 when the wheel is not loaded, i.e. not mounted in the vehicle.

[0046] The loaded tire 1 is deformed at the contact zone 5 between the tire 1 and the ground 3, at the level of its tread.

[0047] At this contact zone, the radius of the tire 1 is defined by the radius under load Rc, which corresponds to the distance between the axis of rotation 7 of the wheel and the ground 3.

[0048] The tire 1 comprises a module 9 for monitoring the tire pressure according to the invention, known under the name “TPMS”, an English acronym for “Tire Pressure Monitoring System” and making it possible to acquire the tire pressure. matics.

[0049] The TPMS module 9 according to the invention comprises hardware and software means adapted to implement the method of the invention. The software means comprise a computer program code means, including in particular the algorithm implemented to execute the method of the invention, while the hardware means comprise an electronic module comprising a tire pressure sensor and a tangential accelerometer adapted to monitor the tangential acceleration of the wheel.

[0050] In one embodiment of the invention, the hardware and / or software means for implementing the method according to the invention can be implemented in an integrated circuit.

[0051] In the wheel position illustrated in [Fig.l], the TPMS module 9 is in contact with the ground 3.

[0052] Figure 2 shows the curve showing an example of a tangential acceleration signal Z seen by the TPMS module 9 as a function of time for a complete rotation of the wheel on which the tire 1 is mounted.

[0053] Considering that the tire 1 rotates at a constant speed, the periodic signal representing the tangential acceleration curve therefore fluctuates around a zero value.

[0054] At the moment when the TPMS module 9 almost comes into contact with the ground when the tire 1 rotates in the direction of the arrow shown in [Fig.l], a pinch zone 11 of the tire 1 (visible in [Fig.l]) is generated between the tire 1 and the ground 3.

[0055] This pinch zone 11 results in a local reduction in the nominal radius Rn of the tire 1.

[0056] Given that the TPMS module 9 continues to rotate at rotation speed eu, the local reduction in the nominal radius Rn of the tire 1 at the pinch zone 11 results in an increase in the tangential acceleration Z seen by the TPMS module 9.

[0057] When the TPMS module 9 has crossed the pinch zone 11, the TPMS module 9 undergoes a strong deceleration because it goes from a positive speed to a zero speed when it arrives in the contact zone 5 with the ground 3.

[0058] This deceleration continues until a minimum peak of tangential acceleration 'Zmin is reached before regaining, via a strong acceleration, its zero value representative of the tangential acceleration perceived by the TPMS module 9 in the contact zone 5 with the ground 3.

[0059] When the TPMS module 9 emerges from the contact zone 5 with the ground 3 and resumes its rotational movement, the TPMS module 9 undergoes a strong acceleration which continues until it reaches a maximum peak of tangential acceleration Zmax before regaining, via a strong deceleration, its zero value representative of the acceleration tangential perceived by the TPMS module 9 when the tire 1 continues to rotate at constant speed.

[0060] In the context of the present invention and as will be seen in the remainder of the description, the method according to the invention provides for monitoring the evolution of variables V included in the group comprising at least the maximum peak of tangential acceleration Zmax and the minimum peak of tangential acceleration Zmin.

[0061] Reference is made to [Fig.3] showing a comparison of a tangential acceleration signal SI of a first tire, shown in bold, and a tangential acceleration signal S2 of a second tire, having a higher state of wear than the first tire.

[0062] The tangential acceleration signal of the second tire has a maximum tangential acceleration peak Z'max and a minimum tangential acceleration peak Z'jnin, both respectively greater, in absolute value, than the maximum tangential acceleration peak ZmaK of the first tire and the minimum tangential acceleration peak Z^ of the first tire.

[0063] Indeed, the second tire being thinner than the first tire due to its greater wear, the radius of curvature of the second tire at the pinch zones 11, 13 is less than that of the first tire.

[0064] Note that other parameters can, however, influence the tangential acceleration signal. These parameters are, for example, the tire pressure, the load applied to the tire, the vehicle speed.

[0065] In the context of the present invention, the variables V that are used can be compensated values, that is to say that the values ​​of the maximum peak of tangential acceleration Zmax, Z'max and the values ​​of the minimum peak of tangential acceleration Zmin, Z'min only reflect the wear of the tire.

[0066] The method implemented to compensate the values ​​of the maximum peak of tangential acceleration Z^y and of the minimum peak of tangential acceleration Zmin by the other parameters is not part of the present invention and is therefore not further described.

[0067] Reference is made to [Fig.4] showing the steps of the method for monitoring the wear of a motor vehicle tire according to the invention.

[0068] The supervision method according to the invention is implemented by the TPMS module 9 of the tire 1 and comprises the following steps aimed at: - step El: acquire, from the tangential acceleration signal of the TPMS module, measurements of at least one variable included in the group comprising a maximum tangential acceleration peak Zmax and a minimum tangential acceleration peak 7 - step E2: process the measurements of said variables acquired during step El, - step E3: compare said processed measurements to a predetermined threshold value, - step E4: issue an alert when said predetermined threshold value is reached.

[0069] Thus, the method according to the invention aims to monitor the evolution of the tangential acceleration over time and to emit an alert signal when the monitored variables V exceed a certain threshold which corresponds to a maximum variation value.

[0070] More precisely, the method according to the invention aims to monitor the evolution of the tangential acceleration over time and to emit an alert signal when a maximum peak of tangential acceleration Zmax or when a minimum peak of tangential acceleration Zmin exceeds a certain threshold, which corresponds to a maximum variation value for the maximum peak or for the minimum peak.

[0071] From monitoring the evolution of the tangential acceleration of the TPMS module 9, the supervision method according to the invention makes it possible to deduce a significant state of wear of the supervised tire.

[0072] Thus, thanks to the present invention, a solution is obtained for monitoring tire wear carried out solely by the TMPS module 9 of the tire 1.

[0073] Reference is made to [Fig.5] to describe a first embodiment of the supervision method of the invention.

[0074] The acquisition step El may include a first sub-step Eli for learning initial conditions.

[0075] The learning step El 1 is typically initiated when the tire to be supervised is new.

[0076] The purpose of the learning step Ella is to determine a reference value Vref of the variable considered, which can be the maximum peak of tangential acceleration Zmax or the minimum peak of tangential acceleration Zmin.

[0077] To do this, in the learning phase El 1, the tangential acceleration signal from the TPMS module 9 of the tire 1 is followed.

[0078] The reference value Vref of the variable considered can be averaged over a predetermined number of kilometers of life of the tire 1 to be monitored.

[0079] For example, the reference value Vref of the variable considered may be equal to the average of the values ​​of the maximum peak of tangential acceleration Zmax or to the average of the values ​​of the minimum peak of tangential acceleration Zmùh for example measured over the first thousand kilometers of the life of the tire 1.

[0080] The learning phase thus makes it possible to determine the value of the maximum peak of tangential acceleration Zmax or the minimum peak of tangential acceleration Zmi„ that the supervised tire is supposed to follow at a predetermined period, for example at the beginning of its life.

[0081] Alternatively, the learning step El 1 may not be implemented and the reference value Vref of the maximum peak of tangential acceleration Zmax or of the minimum peak of tangential acceleration Zmin may be determined by any other means.

[0082] In particular, the reference value V ref of the maximum peak of tangential acceleration Z-max or of the minimum peak of tangential acceleration Zmin can be known from charts and entered in the algorithm for implementing the supervision method of the invention.

[0083] The acquisition step E1 then comprises a second sub-step E12 of acquiring measurements of the monitored variables V, initiated when the reference value Vref is fixed.

[0084] In a first embodiment, the measurement acquisition sub-step E12 comprises the acquisition of measurements of instantaneous variables V(t) corresponding to the instantaneous value of the maximum tangential acceleration peak Zmax or to the instantaneous value of the minimum tangential acceleration peak Zmin.

[0085] In a second embodiment, the sub-step E12 of acquiring measurements is carried out by taking the average y of the consecutive measurements of the variables V monitored.

[0086] For example, a series of measurements of the variables V monitored over a predetermined number of kilometers are carried out, and an average of these measurements is taken in order to deduce an average value V fn / i) of the variable V monitored.

[0087] The consecutive measurements for calculating their average can be carried out over a kilometer range, for example equal to approximately 50 kilometers.

[0088] Step E2 of processing the measurements of the variables V acquired during step El is for example carried out using a so-called “identity” function, which is an affine function of the evolution of the variables V over time.

[0089] On the basis of this identity function, the difference in absolute value between the instantaneous variable V(t) and the reference value Vref, or between the average value and the reference value Vref, is calculated during step E2.

[0090] Reference is made to [Fig.6] detailing the execution of step E3 of the method according to the invention.

[0091] The signal SI shown in bold illustrates a tangential acceleration signal of a reference tire, and the signal S2 is a tangential acceleration signal of a tire being tracked.

[0092] During step E3, the value obtained during processing step E2 is compared with a predetermined threshold value of maximum variation Vxeuu-

[0093] Thus, when the variable monitored is the maximum peak of tangential acceleration Zmax, the predetermined threshold value of maximum variation corresponds to a maximum threshold.

[0094] In the same way, when the variable monitored is the minimum peak of tangential acceleration Zmin, the predetermined threshold value of maximum variation Vseuil corresponds to a minimum threshold.

[0095] According to step E4 of the supervision method of the invention, if | V (?) - Vf> V , then a tire wear alert is generated.

[0096] Similarly, if | Vfn / t}- | > V then a tire wear alert is generated (step E4).

[0097] In the illustration shown in Figure 6, if the difference between the value of the minimum peak of tangential acceleration Z'min of the signal S2 and the reference value Vref of the variable considered (here equal to the value of the minimum peak of tangential acceleration Zmin of the signal SI) is greater in absolute value than the predetermined threshold value of maximum variation Vseuii, then a tire wear alert is generated (step E4).

[0098] The alert can be transmitted for example by radio frequency.

[0099] If the predetermined threshold value of maximum variation Vseuu is exceeded, this means that the variable V monitored (Zmax or Zmin) has increased in absolute value compared to its reference value Vref, and therefore that the tire is worn.

[0100] Given the fact that the value of the variable V monitored that is used is a compensated value that only reflects the wear of the tire, the other parameters that can influence its variation (in particular the tire pressure, the load applied to the tire, the speed of the vehicle) do not impact the triggering of the steps of the method of the invention, in particular step E4 of alert emission.

[0101] Reference is made to [Fig.7] showing an alternative embodiment of the first embodiment.

[0102] In this variant, a step E5 of predicting the remaining mileage before reaching a predetermined wear level of the supervised tire can be initiated.

[0103] Step E5 can be implemented before the predetermined threshold value of maximum variation Vfeui / is reached, that is to say at any time after step E2 of processing the measurements of the variables V acquired during step El is completed, and before step E4 of sending an alert is initiated. A message to the central computing unit is then regularly sent without the predetermined threshold value of maximum variation necessarily being reached.

[0104] Alternatively, step E5 can be initiated as soon as the predetermined threshold value of maximum variation Vsem7 is reached, i.e. following step E4.

[0105] In an exemplary embodiment, step E5 of predicting the remaining mileage before reaching a predetermined wear level of the supervised tire can be implemented periodically.

[0106] The predetermined wear level may, for example, correspond to a total wear level of the supervised tire.

[0107] The extrapolation of the remaining mileage can be obtained from the following formula: Km remaining = Km-1)

[0108] Where: Kmrestanj is the value of the remaining mileage before the predetermined wear level is reached, Km(t) is the current mileage value.

[0109] Alternatively, the extrapolation of the remaining mileage can be obtained from the following formula: Kmremaining = Km( t) j .....r - 1

[0110] The supervision method of the invention can be implemented by a second embodiment.

[0111] It has been observed that throughout the wear of the tire, the value of the variable V followed by the method of the invention increases in absolute value.

[0112] It has also been observed that when approaching the predetermined threshold value of maximum variation Vseui! corresponding to a very advanced or terminal state of wear of the tire, the variations of the variable V monitored (value of the minimum peak of tangential acceleration or value of the maximum peak of tangential acceleration ^max) are much more dynamic.

[0113] This results in an increase in the speed at which the value of the variable V being monitored approaches the predetermined threshold value of maximum variation Vseuii-

[0114] These variations are characterized by the derivative of the variable V followed with respect to time.

[0115] Unlike the first embodiment, the second embodiment does not include a step aimed at learning a reference value of the variable considered (step E1 1 of the first embodiment) or at entering into the algorithm for implementing the method of the invention the reference value Vref of the variable considered known from charts.

[0116] In an execution of the method according to the second embodiment of the invention, the step E1 of acquiring measurements of the variables V can be carried out cyclically by carrying out several measurements of the variable V monitored over a current cycle.

[0117] For example, for an iteration i carried out over a predetermined kilometer window, the variable V monitored on a time basis is periodically measured.

[0118] The kilometer window can for example be equal to 100 kilometers.

[0119] The time base chosen can for example be the minute, that is to say that a measurement is taken every minute.

[0120] Alternatively, it may be envisaged to periodically measure, over the aforementioned predetermined kilometer window, the variable V monitored on a kilometer basis, for example every kilometer.

[0121] Given that there is a running-in phase in which certain parameters specific to the vehicle are put in place, step E1 can be initiated after a predetermined number of kilometers have been traveled by the tire to be supervised.

[0122] Step E2 of processing the measurements of the acquired variables deduces an average value of the variables Vmoy followed on iteration i and an average value of the variables Vmov followed on iteration i-1.

[0123] Step E2 of processing the measurements of the acquired variables then executes a calculation of the derivative over time of the average values ​​of the acquired variables Vmoy, and Vmoy.. acquired for each iteration i and i-1.

[0124] During step E3, the values ​​Vy and A y obtained during r dt mot are compared. dt mm- , ' l ■' zd processing step E2, at a predetermined threshold value Vseuiir

[0125] If ywoy _ ymoy | > V ■> then a tire wear alert is generated (step E4) and transmitted by radio frequency.

[0126] According to an alternative embodiment, step E2 of processing the measurements of the variables executes a calculation of the derivative over time of the average values ​​of the variables Vmoy. acquired on iteration i and of the average values ​​of the variables Vmoy.k acquired on iteration ik, with k>l.

[0127] Thus, the tire wear alert can be generated (step E4) not by comparison between iteration i and i-1 but by comparison between iteration i and i-2, i-3, etc.

[0128] Thanks to this second embodiment, significant variations in the monitored variable V are detected, which makes it possible to deduce that the tire has exceeded its maximum wear level and therefore that the tire is close to the end of its life.

[0129] As goes without saying, the present invention is not limited to the sole embodiments of this method for monitoring the wear of a motor vehicle tire and of this module for monitoring the pressure of the tires for implementing said method, described above solely as illustrative examples, but on the contrary it embraces all the variants involving the equivalents technical means.

Claims

Claims

1. Method for monitoring the wear of a motor vehicle tire (1), implemented by a tire pressure monitoring module (9) mounted in said tire (1) to be monitored, said module (9) comprising a pressure sensor and a tangential accelerometer, said method being characterized in that it comprises the following steps aimed at: - acquiring (step E1), from a tangential acceleration signal of said tire pressure monitoring module (9), measurements of at least one variable (V) included in the group comprising a maximum tangential acceleration peak (Zmax) and a minimum tangential acceleration peak (Zmin), - carrying out (step E2) a processing of said measurements of said at least one acquired variable (V), - comparing (step E3) said processed measurements with a predetermined maximum variation threshold value (Vseuii),- issue an alert (step E4) when said predetermined threshold value of maximum variation Ysemù is reached.,

2. Supervision method according to claim 1, characterized in that said acquisition step (step El) comprises a sub-step (step Eli) of learning initial conditions aimed at determining a reference value (Vref) of said at least one variable (V).

3. Supervision method according to claim 2, characterized in that said reference value (Vref) of said at least one variable (V) is equal to the average of the values of said at least one variable (V) measured over a predetermined number of kilometers traveled by the supervised tire (1).

4. Supervision method according to one of claims 2 or 3, characterized in that said acquisition step (step El) comprises a sub-step (step E12) subsequent to said sub-step (step Eli) of learning initial conditions and comprising the acquisition of measurements of instantaneous variables (VW) or the acquisition of an average value (V^ / )) equal to the average of the values of consecutive measurements of said at least one variable (V) over a predetermined number of kilometers traveled by the supervised tire (1).

5. Supervision method according to claim 4, characterized in that said processing step (step E2) of said measurements of said at least one variable (V) acquired during the acquisition step (step E1) is carried out by applying an identity function on the basis of which a value equal to: - the difference in absolute value between one of said instantaneous variables V(t) and said reference value (Vref), or - the difference in absolute value between said average value (V t)) and said reference value (Vref) is calculated.

6. Supervision method according to claim 5, characterized in that it comprises a step aimed at predicting (step E5) the remaining mileage before reaching a predetermined level of wear of the supervised tire (1).

7. Supervision method according to claim 6, characterized in that said step aiming at predicting (step E5) the remaining mileage before reaching a predetermined level of wear of the supervised tire (1) is implemented consecutively to the alert emission step (step E4).

8. Supervision method according to claim 6, characterized in that said step aiming at predicting (step E5) the remaining mileage before reaching a predetermined level of wear of the supervised tire (1) is implemented before reaching the alert emission step (step E4).

9. Supervision method according to claim 1, characterized in that said acquisition step (step E1) is carried out by periodically measuring said at least one variable (V) for an iteration i and for an iteration ik, k>0, each of said iterations being carried out over a predetermined kilometer window.

10. Supervision method according to claim 9, characterized in that said processing step (step E2) deduces, from the measurements acquired during the acquisition step (step E1): - an average value of said at least one variable (Vfollowed on iteration i, representative of the average of the measurements of said at least one variable (V) for an iteration i, and - an average value of said variable (Vmoy), k>0, representative of the average of the measurements of said at least one variable (V) for an iteration ik.

11. Supervision method according to claim 10, characterized in that said processing step (step E2) is carried out by applying a derivative function on the basis of which a value derived from the average values of said at least one variable (V) is calculated, equal to the difference in absolute value between the derivative with respect to time of the average value of said at least one variable (Vmov) on iteration i and the derivative with respect to time of the average value of said at least one variable (Vmoy ) on iteration ik, k>0.

12. Supervision method according to any one of claims 9 to 11, characterized in that said acquisition step (step E1) is initiated after a predetermined number of kilometers has been traveled by said tire (1) to be supervised.

13. Supervision method according to any one of claims 1 to 12, characterized in that said at least one variable (V) is a compensated value.

14. Module (9) for monitoring tire pressure, comprising hardware and / or software means for implementing the method according to any one of claims 1 to 13, characterized in that said hardware and / or software means are implemented in an integrated circuit.

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