Method and device for detecting tyre wear or the like

• US 20040154715A1
• Filed: 03/25/2004
• Published: 08/12/2004
• Est. Priority Date: 11/20/2000
• Status: Active Grant

• Current Assignee: Dufournier Technologies SAS
• Original Assignee: Dufournier Technologies SAS
• Inventors: Dufournier, Arnaud
• Granted Patent: US 7,391,306 B2
• Time in Patent Office: Days
• US Class Current: 152/154.2
• CPC Class Codes: B60C 11/24 Wear-indicating arrangements
• CPC Class Codes: B60C 2019/006 Warning devices, e.g. devices generating noise due to flat or worn tyres
• CPC Class Codes: Y10T 152/10027 with wear indicating feature

Abstract

The invention concerns a method whereby when the tyre reaches a wear threshold level, acoustic wear indicators emit a sound signal by coming into contact with the ground. Magnetic, optical and mechanical embodiments are also disclosed. A detector consisting of a microphone placed beneath the vehicle and a processing unit switches on an indicator placed in the instrument panel. In a more sophisticated version, the detector by matching the acoustic signal phase with the ABS data, identifies the tyre concerned. The invention is useful for detecting tyre deterioration, or that of any, other type of surface such as pads, and the like, and for detecting the presence of snow chains or nails.

Claims

1. Method to detect the decays of a “

tire”

(in the wide sense defined), that is to detect the moment when its wear level (during and because of its rotation and/or the other movement in the contact of a said surface <

<

of contact >

>

, or because of another cause as chemical attack, corrosion, etc.) reaches a predetermined threshold, characterized in the fact that it includes the incorporation or the setting up in the mass of the tire and/or in the tread pattern channel., groove, or “

rib”

, of <

tread wear indicators >

>

adapted to generate, during their passage on and/or close to the aforementioned contact area, a characteristic and distinguishable signal when the aforementioned wear makes them appear or disappear, in an adapted proportion, the aforementioned incorporation or setting up being even adapted so that the aforementioned signal appears or disappears when the predetermined wear threshold is reached,

Being understood that by “

appears”

or “

disappears”

, we understand that these opposite terms include all the domains of appearance or progressive disappearance of the tread wear indicators and/or of the signal, the signal being considered for “

appearing”

or being considered for having “

disappeared”

when predetermined threshold is reached; and

Being understood that by <

<

characteristic and distinguishable >

>

we shall understand that the tread wear indicators are adapted to produce an appropriate specific signal which is detectable in the detection range of the sensors setting for that purpose, and distinguishable with regard to any background noise or parasite frequency.

2. Process as claimed in claim 1, wherein these “

indicators”

are chosen from among;

fine or coarse particles, aggregated or non-aggregated, and inserts of various dimensions and geometry, including tread designs or shapes integrated into or on the “

tire”

.

3. Process as claimed in claim 1 or 2, wherein the detection principle is chosen from among the following:

The indicators become worn and completely disappear when the level of wear is attained and their absence is then detected by the absence of their characteristic signature.

The indicators are implanted at a depth in such a way as to appear when the level of wear is attained, and their appearance is then detected by the appearance of their characteristic signature;

In both cases, with detection of a predetermined signal threshold (which is on the increase or decreasing)

In both cases, allowing for the possibility that this threshold could still be attained even though the indicators have not completely disappeared or have not completely appeared.

4. Method according to the claim 1 to 3 characterized in the fact that the various modes of realization of the tread wear indicators and the detection are the following ones:

Main “

acoustic”

mode

Secondary modes

Mechanical mode

Electromagnetic mode

With a metal detector version

Optical mode

5. Method according to one of the claims 1 to 4 characterized in the fact that we use tread wear indicators of “

acoustic”

type, generating an acoustic signal, and in the fact that such acoustic indicators can be, either inserts or other pieces, or geometrical forms or adapted tread pattern made, either to generate a specific acoustic signal when going through the contact area, which signal disappears when the aforementioned shape or tread pattern is worn beyond a predetermined threshold, or to generate an acoustic signal by their contact with the contact area when, beyond a predetermined wear threshold of the tire, they are sufficiently appearing, the acoustic wear indicators being inserted into the mass or into the channel, groove etc. (“

rib”

) of the “

tread”

of the “

tire”

(or of any “

zone or wearing surface”

) on the surface or in depth adjusted so as to contact the ground (or any “

contact area”

) when the limit of wear is reached.

6. Process as claimed in any of claims 1 through 4, wherein when the tire is worn down to the indicator, the latter will repeatedly strike the ground during travel and therefore generate an acoustic signal, the indicator being either of the single unit type or of the mobile hammer type M striking on a base B implanted in the rubber.

7. Process as claimed in any of claims 1 through 6, wherein this acoustic signal is a function of the number of indicators coming into contact with the ground, but also of their position, the speed of the vehicle and acoustic characteristics of the indicators inserted in the tire, and wherein the signal comprises a base frequency (selected by a persons skilled in the art to be specific and differentiable by design and integration or “

implantation”

of the indicators in the tire) corresponding to acoustic frequency fa natural to the indicator inserted in the tire and appears each time an indicator comes into contact with the ground, the “

natural frequency”

of the indicator to be taken into consideration being the frequency of the indicator when it is in position in the “

tire”

.

8. Process as claimed in claim 7, wherein the signal fa is also modulated by a function ft which is a function of the number of indicators, their layout or “

implantation”

, but also of the rotational velocity of the wheel, this function ft being a harmonic function of the wheel revolution and also being predetermined to be specific and differentiable and/or to carry additional information.

9. Process as claimed in claim 7 or 8 wherein several series of indicators can be combined which are arranged in a transverse position in relation to the “

tire tread”

, with at least one indicator per wheel azimuth, each series corresponding to wheel azimuths which differ at least in part, and thus a characteristic is obtained ft1, ft2, ft3 for different series of indicators, with series 1 corresponding to azimuths a, b, c, d, series 2 to azimuths a (or different from a), e, f, g, h, i, etc., and wherein the Process is characterized by the fact that in the case of multilevel detection, the different levels can have different indicators having an acoustic signature fa natural to each level and/or a special implantation of the indicator can be used corresponding to each level of detection (typing of ft for each level of wear.

10. Process as claimed in any of claims 1 through 9, wherein it includes signal processing for the purpose of general extraction A) of the wanted signal S(t) and which comprises the following steps:

B) extraction of the indicator signal and/or

C) extraction of the implantation signal, and

Optionally other steps with additional improvements, such as;

identification of the wheel at fault, and/or optimization of the volume and time of calculation, and/or differentiation processing in relation to other vehicles

11. Process as claimed in any of claims 1 through 10 wherein the following steps are carried out:

1. Extraction of the wanted signal S(t);

the following processing operations are carried out from the basic signal;

Extraction of the tread wear indicator signal

We make a digital or analog filtering aiming at keeping only the signals corresponding to the natural frequency (ies) of the characteristic signal of the tread wear indicator inserted into the tire.

Extraction of the setting up signal

As a result of the rotation of the wheel, the setting up distribution of the tread wear indicators in the tire leads to a harmonic “

modulating”

signal of the round of wheel and we use this property to extract, from the basic signal, the signals appearing at the harmonic frequencies of the round of wheel, corresponding to the setting up of the wear indicators we try to detect, Fi(t) being the modulating signal corresponding to a wheel and to a level of wear, that is to say to a setting up.

12. Process as claimed in any of claims 1 through 10, wherein the following steps are carried out:

1. Extraction of the wanted signal S(t);

the following processing operations are carried out from the basic signal;

Extraction of the indicator signal

n acoustic mode, the acoustic frequency natural to the indicator inserted in the tire will be used.

13. Process as claimed in any of claims 1 through 10 wherein the following steps are carried out:

1. Extraction of the wanted signal S(t);

the following processing operations are carried out from the basic signal;

Extraction of the indicator signal

In the event that there are several indicators, each corresponding to a level of wear detection, this latter operation will be performed for each type of indicator set each time to the frequency (or frequencies) natural to the signal of the indicator under consideration and inserted in the tire, the extracted signal then being Si(t).

14. Process as claimed in any of claims 11 through 13, wherein in the implantation signal extraction step, said demodulation can be carried out from a correlation between the basic signal and the modulating signal, this modulating signal being successively each of the signals Fi(t) corresponding to a wheel (or in a simpler embodiment to a part of, or the entire set of, wheels) and to a level of wear to be detected and corresponding to one implantation.

15. Process as claimed in any of claims 11 through 13, wherein in the implantation signal extraction step, to create these modulating signals Fi(t), the signal supplied by the wheel speed sensors of the ABS can be taken, which will then be modified as a function of the different implantations, each corresponding to a level of wear.

16. Process as claimed in any of claims 11 through 13, wherein in the implantation signal extraction step, in the case where there is no ABS™

information available or individual wheel speed information available, we can take as the speed information signal—

in order to comprise the “

implantation information” and

before correlating it with the basic signal—

the vehicle speed information present on the vehicle.

17. Process as claimed in any of claims 11 through 13, wherein in the implantation signal extraction step, in the case where there are several implantations, each corresponding to a level of wear detection, this latter operation will be performed for each implantation, set each time on the “

modulating”

signal corresponding to each implantation, the result being called Si(t).

18. Method, according to one of the claims 1 to 6, characterized in the fact that it includes possibly stages of additional improvements:

Identification of the incriminated wheel;

In bend, or due to various torques on axles and even on wheels, we can consider that each wheel has its own speed and, on a sufficient delay, the determination of the wheel is possible by a follow-up of the signal phase and a comparison with regard to each of the wheel speeds;

Moreover, as generally and particularly during a long time, vehicles are not strictly running at the same speed, we make the measurement during a sufficiently long period (few seconds to several minutes) to avoid any confusion with an identical close vehicle;

Thus, we can successively compare the phase of the basic signal with representative signals of the speed of each of the wheels (in a preferred example we shall take for these last signals, the signals of wheel speed supplied by the ABS™

sensors).

and that is used to deduce the wheel(s) which has/have reached the wear level.

19. Process as claimed in any of claims 1 through 17, wherein the conventional techniques of digital or analog phase lock loop can be used.

20. Process as claimed in claim 18 or 19, wherein it comprises a step of Optimization of the calculation time and volume.

the Hadamard transformation gate is used to calculate the correlation between the basic signal and the implantation signal.

21. Process as claimed in claim 20, wherein the Hadamard transformation gate will be applied to the basic signal in phase quadrature (processing applied only to the module and phase elimination).

22. Process as claimed in claim 20, wherein once detection is confirmed, there is a switch to phase analysis mode (saving on CPU time) because it has been confirmed that at least one of the wheels is worn, and the aim then is to determine which one or which ones are worn by interrelation between the acoustic signal and the wheel being examined (wheel harmonics), this switch completed for example after vehicle contact cutoff, thus a return to detection mode until reconfirmation of detection and switch back to phase analysis mode.

23. Process as claimed in claim 20, characterized in the fact that the extraction is only made in domains or ranges favorable to the measurement (that is conditions not generating a parasite noise which would be so important that it would modify, falsify or saturate the wear indicator signal), provided that we are enough frequently in these domains so that the evolution of the wear of the tire has no time, between two favorable periods, to reach a dangerous level:

we can choose a favorable speed range, and/or a duration from a few seconds to several minutes long;

Speed range from 20 to 60 kph and detection after one minute of monitoring; and

/or

dry time (no rain) and/or

no loose road grit

and the monitoring period can correspond to a period whose beginning is defined by the starting up of the vehicle.

24. Process as claimed in claim 23, wherein the duration of detection is accelerated if the detection was already positive in the preceding sweep.

25. Process as claimed in claim 18 or 19, wherein it includes Differentiation from other vehicles:

since vehicles generally do not travel at exactly the same speed and in particular over a long period of time, the measurement will be performed over a time period (several seconds to several minutes) sufficiently long to ensure that the confusion with an identical vehicle traveling alongside will be avoided.

this approach is reinforced by phase analysis, as mentioned previously in detection of the wheel at fault, in order to differentiate signals coming from its own wheels versus those coming from the other vehicle.

26. Method, according to the claim 9, characterized in the fact that it includes a stage of <

<

comparison—

spatial adjustment >

>

between a front wheel and a rear wheel during the calculation of the C factor (factor for the comparison of the tested wheel to a reference wheel or normalization of the signal)

In the case of an tested front wheel is compared with a rear wheel, the function will be;

C(t)=Si(t)−

Sj(t+Δ

t)

Si corresponds to the front wheel

Sj corresponds to the rear wheel

With

Δ

t=e/V

V=speed of the vehicle

e distance between front and rear axles.

V is calculated for example from the average speed of the non driving wheels or the average speed of all the wheels.

In the case of a comparison with a set of wheels, we shall spatially adjust each of the wheels before calculating the average criterion Sj of reference wheels.

The calculation of the Di function being then the following one;

$\mathrm{Di}<br><br>\left(t\right)={\int <br><br>}_{x=t-\mathrm{T1}}^{x=t}<br><br>C<br><br>\left(x\right)<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>x$

27. Process as claimed in any of claims 1 through 26, wherein it comprises a step in which instantaneous wear information is evaluated.

28. Process as claimed in any of claims 1 through 27, wherein for each of the wheels values D1(t), D2(t), D3(t) and D4(t) are calculated, this list here being enumerated for a four-wheel passenger car, and

these values allow monitoring of the development of wear for each of the wheels,

$\mathrm{Di}$

(t)=∫

x=t-T1x=t

Si

(x)

 





x

Order of Magnitude;

T1;

Several fractions of seconds to a few dozen minutes.

29. Process as claimed in claim 28, wherein to perform and simplify the calculations, integrals will be replaced with sliding sums of successive values of the wanted signal Si(t) for numbers of terms corresponding more or less to time period T1.

30. Process as claimed in claim 28, wherein the time period T1 is replaced with a spatial length of progress of vehicle d1, which could for example be evaluated by the number of “

tops”

of signals transmitted from the ABST”

encoders.

31. Process as claimed in claim 28, wherein in the case of detection at several levels, a function Di(t) will be calculated for each Si(t);

Si(t) being the signal corresponding to a wear level and to a wheel and therefore a number calculated to be the value of Di(t) will be used which corresponds to the number of wheels under examination multiplied by the number of detection levels;

in order to make the calculations easier, initially all that is needed is a calculation of Di(t) per level of wear, this value then signifying that the wear level i has been reached by at least one of the wheels.

32. Method according to one of the claims 1 to 31, characterized in the fact that it includes a stage for the extraction of the final information according to which the Di (t ) values are compared each with individual thresholds Sli;

and possibly

In the fact that this threshold Sli can be wheighted by the outside hygrometry (rain sensors used to manage the windscreen wipers) or by the average speed of the vehicle

These tests are followed by counters which increment and decrement according to the results of the tests (when a counter Cpti exceeds a predetermined threshold, then we know that the corresponding wheel (or the corresponding wheels) has reached the corresponding wear level).

33. Process as claimed in any of claims 1 through 32, wherein it may also include steps making it possible to improve the accuracy of detection, chosen from among the following:

The steering angle can be used to invalidate measurements beyond a limiting deflection angle. Results of measurement are then considered as nonexistent throughout the duration of the time the limiting angle has been exceeded, the counters Cpti remaining in that case unchanged;

Knowledge of the steering angle can be obtained from information already available for certain devices such as the electronic stability monitor;

Knowledge of external hygrometry (air humidity measurement) will make it possible to improve extraction of final information by weighting the Sli thresholds;

This knowledge can be obtained using rain sensors, which would serve, for example, to control the windshield wipers;

Knowledge of the internal pressure of the tire casing would make it possible to improve extraction of final information by weighting the Sli thresholds;

This knowledge could be obtained from pressure sensors implanted in the wheels;

The Sli thresholds could also be weighted by the average speed of advancement progress of the vehicle;

by the distance covered throughout the period T1 and/or the time it takes to cover distance d1.

34. Process as claimed in claim 33, wherein the Sli thresholds could also be adjusted by learning, by using a learning period during which it will be determined that the tires are not worn.

35. Process as claimed in claim 34 wherein the learning process is initiated upon an external order (onboard computer, tire monitoring system, pressure monitoring system, onboard or remote diagnostics and maintenance) or by human intervention (driver or operator).

36. Process as claimed in claim 34, wherein the learning period corresponds to a specific period:

for example, the thresholds will be set in relation to values of Di(t) for a period after the time the vehicle is first put into service.

37. Process as claimed in claim 34, wherein the learning ability makes it possible to determine in particular a function Sli =f(V) with V:

speed of the vehicle.

38. Process as claimed in claim 34, wherein the learning is an ongoing process, the Process chosen consisting—

on the basis of a prior condition—

in learning the level of signal Di(t) when a level of wear has been attained and to reset thresholds Sli as a consequence.

39. Method according to one of the claims 1 to 38 characterized in the fact that it includes

Secondary modes

Mechanical mode

Electromagnetic mode

With a metal detector version

Optical mode

And in the fact that:

the mechanical mode

We detect the signal made up of vibrations generated by hanical wear indicators. These indicators are made in material (identical to those aforementioned) of higher hardness level than the tread of the tire and inserted into this latter one. They appear on the surface of the tire when the level of wear corresponding to the detection level is reached, and create then a localized tire radius variation, then it involves variations of angular speed of the tire, the wheel and then vibrations of the tire, the wheel, the hub and the suspension;

The detection is then made preferentially with wheel speed sensors (for example those of the ABS™

) or accelerometers or force measurements or movement sensors setting up on the wheel, the hub, the suspension or the body.

40. Method according to the claim 39 characterized in the fact that

In the electromagnetic mode

We detect the signal linked to the presence, the appearance, the missing, the decrease of tread wear indicators generating a magnetic or electric field, and

Tread wear indicators made up of ferromagnetic materials or charged with ferromagnetic particles (notably charged elastomers) are inserted into the tread and wear out with the rest of the tread, and we detect their signal weakening gradually up to a threshold which activates the alarm, or, indicators are setting in the tread and gradually appears, and we detect their signal becoming perceptible up to a threshold which activates the alarm;

and possibly

We charge directly the tread (up to or from a certain depth corresponding to the predetermined detection level, by disappearance or, respectively, appearance of ferromagnetic particles) during the extrusion or in a phase of manufacture taking place between the extrusion and the cooking (or after manufacture);

The tread wear indicator is made up of metallic particles inserted into the tread and the detection is made by means of metal detector sensors, these particles are then inserted up to the depth of predetermined level of wear in order to have totally disappeared when the level of wear is reached;

We detect the presence of tread wear indicators such as insert;

On the opposite, we monitor the appearance of the signal of inserts or particles implanted in depth, and not the disappearance of the signal of inserts or particles setting or “

charged”

in the surface of the tread.

41. Method according to the claim 39 characterized in the fact that

In the optical mode

We detect the signal corresponding to the presence, the appearance, the decrease or the absence of a light signal contrasting with the rest of tread;

We use tread wear indicators made of materials of clear color (or sharply contrasting with the rest of the tread) such as for example colored or white elastomers or reflecting such as for example metal elements, which are inserted into the tread and wear out with the rest of the tread, up to a threshold which activates the alarm, or such tread wear indicators which are implanted in the mass of the tread and gradually appear, their signal becoming perceptible up to a threshold which activates the alarm;

We charge directly the tread of reflecting or colored material during the extrusion or in a phase of manufacture located between the extrusion and the cooking (or after manufacture);

The detection is made by using light sensors (for example diodes) with a lighting localized (which can be made by luminescent diodes) which are setting up in the suspension (preferably on the strut or equivalent) or on the body (preferably in the wings) or in a preferred mode on a support as described in example, arm which allows a facing and close to the tread location;

56. Device according to one of the claims 15 to 21 characterized in the fact that it uses a

Mechanical mode

The signal is made up of vibrations due to mechanical tread wear indicators made of a material (identical to those quoted previously) harder than the tread of the tire and inserted into this one;

The detection is preferentially made by wheel speed sensors (for example those of the ABS™

) or by accelerometers, or force or movement sensors, set up on the wheel, the hub, the suspension or the body.

57. Device according to one of the claims 15 to 22 characterized in the fact that it uses an

Electromagnetic mode

the signal is made up of the presence, the appearance, the decrease or the absence of a magnetic or electric field;

and the device includes, for that purpose, tread wear indicators made up of ferromagnetic material or material charged in ferromagnetic particles (notably charged elastomers) which are inserted into the tread and wear out with the rest of the tread, their signal weakening gradually up to a threshold which activates the alarm, or are set up in the tread and gradually appear. Their signal become perceptible up to a threshold which activates the alarm;

the tread is directly charged by such particles or by such materials (on, or, at a certain depth corresponding to the beginning of the selected detection, by disappearance or, respectively, appearance of ferromagnetic particles) during the extrusion or in a phase of manufacture located between the extrusion and the cooking, or after manufacture;

Magnetic and\or electric field sensors set in the suspension (rather on the strut or similar device) or on the body (rather in the wings);

And in the fact that, the wear indicator is made up of metallic particles inserted into the tread and the detection is made using a metal detector sensor, that detects particles or metal inserts being then inserted until the depth of the select wear level, to have totally disappeared when the level of wear is reached, and in the fact that using this sensor we can monitor the disappearance of these tread wear indicators, or metallic particles incorporated in depth, or on the opposite, we can detect the appearance of the signal of inserts, and not the disappearance of the signal of inserts or particles implanted or introduced in surface, and in the fact what the “

detector”

generates an electromagnetic field which is modified by the appearance or the disappearance of particles or metal inserts (which are thus passive), this modification being detected by a sensor integrated into the “

receiver”

;

We use a support to locate the sensor or several sensors closer to the tread for a better monitoring and preferably three sensors respectively located in the external shoulder (or sidewall), the middle (or centre, or appreciably the centre) and the internal shoulder (or sidewall) of the tread of the tire. The support is similar as the one described in the previous claims.

This support can be a bar, including one or several sensors positioned transversely with reference to the wheel, or a flat or concave surface following the wheel shape, possibly wide so as to accept staggered sensors or others asymmetric arrangements (that allows for example to use various azimuth) or various kind of sensors corresponding to the four modes described, or corresponding to a single mode but with various dimensions or characteristics, so as to generate various natural frequencies fa,

And on the opposite, we can monitor the appearance of the signal corresponding to inserts or particles implanted in depth, and not the disappearance of the signal of inserts or particles implanted or “

charged”

superficially.

58. Device according to one of the claims 15 to 23 characterized in the fact that it uses one

Optical Mode

The signal is due to the presence, the appearance, the decrease or the absence of a light signal contrasting with the rest of the tread.

And tread wear indicators are made up of clear color materials (or sharply contrasting with the rest of the tread) such as for example colored elastomers or white one or reflecting one such as for example metallic elements inserted into the tread that wear out with the rest of the tread, up to a threshold which activates the alarm, or are incorporated in the tread and gradually appear, their signal becoming perceptible up to a threshold which activates the alarm;

And/or the tread is directly charged by reflecting or colored material, during the extrusion or in a phase of manufacture included between the extrusion and the cooking (or even charged after manufacture);

And

Optical sensors (for example diodes) with possibly a localized lighting (which can be made for example by luminescent diodes) set up in the suspension (rather on the strut or similar element) or on the body (rather in the wing) or in a highly preferred mode on a support as described in the previous claims, which allows to be located in front of and close to the tread.

60. Manufacturing process of “

tires”

characterized in the fact that tires are equipped with at least one device according to one of the claims 15 to 24.

The wear indicators insertion can be made;

During manufacture;

with possibly a tire angular adjustment in mold,

After or during manufacture, setting up in a channel or a groove or “

rib”

, claws setting on both sides in blocks.

63. Device, according to one of the claims 15 to 24, characterized in the fact that it is fitted on a development vehicle:

Rover™

75

And in the fact that;

Metallic tread wear indicators are inserted into the tread of every tire;

this setting up includes a single kind of wear indicator (in stainless steel). The indicator distribution includes two sets of 12 tread wear indicators distributed for the first setting up (depth of tread pattern;

2 mm) on tire azimuths 0°

, 90°

, 180°

, 270°

with three wear indicators on each azimuth (inner shoulder, middle of the tread, outer shoulder) and for the second setting up (corresponding to the legal wear limit;

1,6 mm) on tire azimuths 0°

, 45°

, 180°

, 225°

with three wear indicators on each azimuth (inner shoulder, middle of the tread, outer shoulder);

The basic signal is delivered by a microphone approximately located in the middle of the body, recessed with regard to body in order to be protected from the projections and from the noise generated by the exhaust pipe;

We use for the wheel speed measurements the pre-set Siemens Automotive™

sensors used for the Bosch™

ABS™

unit.

The signals delivered by these sensors are then transmitted to a central unit located near the ABS™

;

This central unit consists of two electronic parts;

An analog part that conditions the analog and digital incoming signals, includes the power card as well as the conditioners for the outgoing signals

A digital part, build up around a 8 bits microcontroller and that makes all the data processing.

The device is in the active mode only in the range from 20 to 60 kph, outside this domain, the data are considered as non-existent and the counters values and the Si signals do not evolve;

In the domain of activation;

The signals delivered by the wheel speed sensors are conditioned at first by the analog card to be digitized and used by the digital card.

From the description of the setting up of the tread wear indicators for both selected levels of wear and the wheel speed signals supplied by the ABS™

sensors, the digital card calculates the Fi(t) signals for both selected levels of wear (2 mm and 1.6 mm) and for each of the wheels, that is to say 8 signals.

The analog card filters the basic signal Sb with a band pass filter centered around the tread wear indicator frequency 3500 Hz (as the tread wear indicators used are identical for both levels of wear).

By means of an algorithm notably using the Hadamard transform (that avoid data recording and too complex operations for a 8 bits microchip such as multiplication or addition) applied to the basic signal in phase quadrature (data processing applied only to the modulus and elimination of the phase), it extracts the useful signal.

It integrates then (memory) the eight signals Si(t) on a duration of 2 s and extracts by means of eight evolving thresholds Sli (linked to the speed and fixed by self-learning) the values of the counters (Cpti).

The final information is shown on the dashboard using a pictogram which remains off in the absence of detection, which flickers when a detection of the first level (2 mm) occurs, which becomes permanently red for the second detection level (1,6 mm).

Counters are adjusted to evolve from 0 to 255.

If one of the counters is superior to 200, the alarm (visual and acoustic alarm) corresponding to the wear level and to the wheel is activated, it switches off only when the counter is below 170. The distance between the value of ignition and the value of extinction eliminates unpleasant flickering of luminescent diode during the change of state.

This information is also supplied to a cruise control which was modified to modulate its speed according to the wear level when raining (rain is monitored by an additional sensor used for wipers automatic activation).

64. Process as claimed in any of claims 1 through 39 wherein it includes Differentiation of extraction zones wherein detection only works under favorable detection conditions, as long as said conditions are chosen in such a way that the “

vehicle”

has the opportunity to “

override”

them at time intervals which are sufficiently short so as not to allow, between two favorable detection zones, a dangerous progression in the tire'"'"'s wear, the favorable environment zones being zones where the receivers and electronics will not be disturbed by phenomena which cause congestive, jamming or even system-saturating spurious noise, such as speed exceeding a certain threshold (and in addition to this, overly high aerodynamic noise), rain (in case of rain, considerable spurious noise is caused by water being thrown up on the car body, the chassis, the receiver, etc.), presence of loose road grit (same result), and other situations, and wherein;

in a “

favorable range”

where the parameters are predetermined and stored to memory (and optionally adjustable by the manufacturer or the automobile dealership depending on the country where the vehicle is going to be used), the process and the device as claimed in the invention operate and detect wear;

in an “

unfavorable”

range where the parameters are predetermined and stored to memory (and optionally adjustable by the manufacturer or the automobile dealership depending on the country were the vehicle is going to be used), the process and the device as claimed in the invention remain in an “

idle”

state, that is, they do not take into account received data;

as soon as the car returns to a favorable range, the process in the device as claimed in the invention return to active mode and once more classify the data as usable and the sensor is once more able to change the detection status;

and wherein a favorable speed range could for example be chosen, and/or a time period ranging from several seconds to several minutes long, for example a “

favorable”

speed range 20-60 km/hr and detection after one minute, and/or “

favorable”

range of dry road and/or absence of loose road grit, and the like,

and wherein,

the system electronics can be preprogrammed so that when entering an unfavorable zone, it records and stores to memory (after, for example, a time lag of one minute) the average characteristics of the spurious noise (average intensity, average frequencies, etc.) in order to be able to detect rapid AND repeated anomalies (rapid=delta time to be preset) appearing in relation to this reference spurious noise over optionally a minimum preprogrammed period of 20 seconds or one minute and alert the driver and optionally also other onboard systems;

the area examined could also for example correspond to a period, the beginning of which is defined by startup of the vehicle and

the detection period could also be accelerated if detection was already positive in the preceding sweep.

65. Process as claimed in any of claims 1 through 39 and 64, wherein it includes a “

comparison-spatial reset”

step between a front wheel and a rear wheel, for example during calculation of factor C (factor of comparison of the wheel being tested to a reference wheel (or normalization of the signal)), in order to perform a comparison of the two wheels called “

iso-ground”

, that is, the coefficient C incorporating the spatial reset makes it possible to efficiently circumvent problems associated with unevenness of the ground, such as bumps, ruts, etc., and wherein

in addition to the spatial reset, wheels situated preferably on the same side of the vehicle are also taken into account,

in the case of a front wheel being tested compared to a rear wheel, the function will be;

C(t)=Si(t)−

Sj(t+Δ

t)

Si corresponds to the front wheel

Sj corresponds to the rear wheel

e wheel base (or the gap between the two wheels considered)

Δ

t=e/V

with V=speed of advancement of the vehicle

V being calculated on the basis of the average speed of the non-driving wheels or the average speed of all the wheels taken Together.

in case of comparison with a set of wheels, each of the wheels shall be spatially reset before calculating the average criterion Sj of the comparison wheels.

Calculation of the function Di will then be as follows;

$\mathrm{Di}<br><br>\left(t\right)={\int <br><br>}_{x=t-\mathrm{T1}}^{x=t}<br><br>C<br><br>\left(x\right)<br><br>\text{\hspace{1em}<br><br>}<br><br><br><br>x$

67. Applications of the methods and the devices according to claim 1, to any vehicles (in the wide sense indicated, that is to say vehicles, mechanical elements, and so on) powered or not, equipped with “

tires”

provided with treads or wearing surface, worn by any type of wear, including corrosion, chemical attack, and to industrial machines or elements, and to any kind of movement (s) involving the wear (rotation, translation, more complex movements . . . ) and to a skate of gliding setting up on a dump truck or similar vehicle or a slipping pad or an element of a rotor of helicopter, or a lubrication shaft bearing for a propeller of a ship and equivalent devices.

42. Device to detect the decays of a “

tire”

(in the wide sense defined), that is to detect the moment when its wear level (during and because of its rotation and/or the other movement in the contact of a said surface <

<

of contact >

>

, or because of another cause as chemical attack, corrosion, etc.) reaches a predetermined threshold, characterized in the fact that it includes “

tread wear indicators”

incorporated or set up in the tire and adapted to generate, during their passage on and/or close to the aforementioned contact area, a characteristic acoustic and distinguishable signal when the aforementioned wear makes them appear or disappear, in an adapted proportion, the aforementioned incorporation or setting up being even adapted so that the aforementioned signal appears or disappears when the predetermined wear threshold is reached

Being understood that by “

appears”

or “

disappears”

, we understand that these opposite terms include all the domains of appearance or progressive disappearance of the tread wear indicators and/or the signal, the signal being considered for “

appearing”

or being considered for having “

disappeared”

when predetermined threshold is reached; and

Being understood that by <

<

characteristic and distinguishable >

>

we shall understand that the tread wear indicators are adapted to produce an appropriate specific signal which is detectable in the detection range of the sensors set for that purpose, and distinguishable with regard to any background noise or parasite frequency.

43. Device according to the claim 42 characterized in the fact that the aforementioned “

tread wear indicators”

are chosen among;

either fine or unrefined, agglomerated or not particles, and inserts of various dimensions and shapes, including specific tread pattern or integrated forms, in or on the “

tire”

, adapted for, either generating a specific acoustic signal when going through the contact area, which signal disappears when the aforementioned shape or the sculpture is worn out beyond a predetermined threshold, or to generate an acoustic signal when going through the contact area, when they sufficiently appear, beyond a predetermined wear threshold.

44. Device as claimed in claims 42 or 43 wherein two detection principles can be used:

The indicators become worn and completely disappear when the level of wear is attained, and their absence is then detected by the absence of their characteristic signature.

The indicators are implanted at a depth in such a way as to appear when the level of wear is attained, and their appearance is then detected by the appearance of their characteristic signature;

In both cases with detection of a predetermined signal threshold (which is on the increase or decreasing)

In both cases, allowing for the possibility that this threshold could be attained when the indicators have not completely disappeared or have not completely appeared.

45. Device according to one of the claims 42 to 44 characterized in the fact that the setting up is transversely made (that is to say according to an azimuth of wheel) in at least one, and preferably several locations of the tread (or in general way of the surface or the wearing zone).

46. Device as claimed in claim 45 wherein a transverse implantation is performed in three locations:

one centered, one on the internal sidewall, one on the external sidewall, either within the rubber mass or in a groove or slit or “

rib”

of the tire, or both.

47. Device as claimed in any of claims 42 through 46 wherein in the fact that this transverse setting up is “

longitudinally”

repeated on a certain number of azimuths, the choice of which is adapted to generate a signal, or sets of signals, characteristic and distinguishable, for example 90, 120, 145, 180, 270°

for a first series and other azimuths for every other series, certain azimuths which can be the same for several series, notably the first azimuth,

and we can use several longitudinal series of tread wear indicators'"'"' setting up, each being defined;

By a set of azimuths and

By the distribution, the number, the transverse setting up of the tread wear indicators, possibly according to different setting up for each series,

the set forming a combination generating, for every series, a specific and distinguishable signal,

to distinguish the signature of the tread wear indicators from a signature generated by parasites as for example stones inlaid in the tread pattern,

the number of the longitudinally arranged tread wear indicators is preferably high in order to compensate the loss or the destruction of one or several of them,

the tread wear indicators can be identical or different in number, setting up and nature, according to the series, nevertheless, in order to increase the discrimination between the levels of detection, we can select a type of tread wear indicator for each level, or still to distinguish the wear of a particular zone of the tire (for example asymmetrical tread shoulder wear) we can use in this zone a specific kind of wear indicator,

the tread wear indicators are preferably the same for all the series;

the tread wear indicators are distributed in a identical way or not, according to the series and possibly in different combinations;

the upper part of the tread wear indicators is at a height such as they will contact the ground when the legal wear level or chosen wear level is reached;

this height can be slightly raised to warn the driver before the limit of wear is reached.

48. Device according to one of the claims 42 to 47 characterized in the fact that the acoustic, electric or magnetic sensors, can be set on a support which allows to position them in front of the tread and

this support is fixed to the hub or on an element of the suspension, so that, the support follows the movements of the steering wheel when steering.

on a support made for three sensors respectively located in the external shoulder (or sidewall), the middle (or centre, or appreciably the centre) and the internal shoulder (or sidewall) of the tread of the tire;

by bringing the sensors into close contact with the tire tread, for better detection, by positioning the sensor(s) on an arm, for example, situated in the wheelhouse, above the tire tread, and including at least one but preferably three sensors, one positioned in relation to each right and left sidewall (that is, external or internal) of the tire and a third being positioned more or less in regard to the center of the tread;

this arm being of any shape and dimensions, such as a bar incorporating the sensor(s) and positioned transversely to the wheel, or on the other hand a flat or concave surface following the profile of the wheel, wide enough to accommodate either sensors placed in a staggered configuration or some other asymmetrical layout, or different types of sensors corresponding either to the four modes described or to a single mode but with dimensions or other characteristics which are different, in such a way as to generate different natural frequencies fa.

49. Device according to one of the claims 42 to 48 characterized in the fact that the various modes of realization of the tread wear indicators and the detection are the following ones:

Main “

acoustic”

mode

Secondary modes

Mechanical mode

Electromagnetic mode

With a metal detector version

Optical mode

50. Device according to one of the claims 42 to 49 characterized in the fact that in

Main “

acoustic”

mode

the wear signal is made by “

acoustic”

wear indicators whose function is to generate or stop generating sound or acoustic signal in the contact area, when the wear indicators appear or disappear,

the signal transmission is made through the air (and probably through mechanical elements)

the detection is made by one or several microphones (or possibly accelerometers, the sensibility of which in the frequency range of the tread wear indicators signal is good, or others classical or future sensors able to do the same);

51. Device as claimed in any of claims 42 through 50, wherein it includes

one or more acoustic indicators or transmitters, which can be either inserts or other components, or geometric shapes or tread designs adapted either to generate a specific acoustic signal upon contact with the contact surface, said signal disappearing when said form or design tread is worn down beyond a predetermined threshold, or to generate an acoustic signal by their contact with the contact surface when they reach a predetermined tread wear threshold of the tire and as a result make a certain degree of appearance.

the acoustic indicators or transmitters are inserted in the mass and/or in a groove or slit or “

rib”

of the tire;

at least one “

receiver”

(in the broad sense, that is, including at least one sensor, and optionally at least one support, such as for example an arm or the like, and optionally at least one electronic package or relay or central computer and like units such as a transmitter.)

whose primary function consists in detecting the presence of the characteristic acoustic signal indicating that the wear limit of the tire has been reached, and the secondary function of which consists in identifying which wheel(s) is transmitting the signal.

52. Device as claimed any of claims 42 through 51 wherein the acoustic transmitter includes an:

Active part (sound emission function at the time of contact with the ground or the “

contact surface”

);

these elements will be fashioned of a strong material and shall be

simple;

small ceramic component for example

mechanical;

functions by striking, for example a mobile component of the hammer type M (in contact with the contact surface) on a base B anchored in the tire;

single unit;

composed of a solid and sound-conducting material of the ceramic type or hollow and metallic (inexpensive, effective)

and

one or more of the following materials can be used;

Metals and alloys (steel, etc.)

Minerals (glass, ceramic etc.)

Composites, fiberglass, ceramic composites

Polymers or elastomers (example;

elastomers with high modulus x>

20 Mpa, formaldehyde resins, bakelite)

Plastics or thermoplastics

and wherein it also includes an attachment part;

Part for attaching to the rest of the tire;

Attachment base;

of the claw type (or similar B shapes which resist removal) embedded in the slabs of rubber and/or positioned in the grooves, preferably longer than it is wide (better resistance to longitudinal loads).

the attachment being done as follows;

Using claws or similar shape inserted in the slabs of rubber

Using glue

By vulcanization and adhesion of different interfaces when the tire is baked or later when the indicators are implanted.

53. Device as claimed in any of claims 42 through 52, wherein the indicator can be coated with a material which is intermediate in terms of hardness between the indicator and the material of which the tire is made, said material being adapted in such a way that it preferably has three functions, including but not limited to the following:

To create a progressive gradient of hardness between the tire material and the indicator in order to most favorably distribute the mechanical shear stresses.

To serve as intermediate adhesive material between the indicator and the tire material.

To protect the indicator from external assaults (mechanical or chemical) before this coating is removed by wear.

54. Device as claimed any of claims 42 through 53, wherein in its preferred embodiment it comprises acoustic sensors, microphones, implanted in the following manner:

Implantation of microphone(s)

the number of microphones (sensor capable of detecting the acoustic signal transmitted) to be implanted will be one for each wheel to be monitored, or one per pair of twinned wheels, one per axle, or one for the entire vehicle, with mixed configurations of these also being possible.

If one microphone per wheel is used, implantation will be on the chassis or on elements which comprise the ground connection, or the wheel, or the tire.

If one microphone is used per axle, implantation will be on the chassis or on components comprising the axle or the ground connection system of said axle.

If one microphone is used for the entire vehicle, implantation will be done on the chassis or on any component affixed thereto. and

In the case of a chassis implantation;

The microphone will be implantation in or under the vehicle chassis, more or less in the middle and more or less equidistant between the four tires.

It should not be too close to the exhaust conduit, and will be recessed with respect to the plane of the chassis in order to be better protected from the noise created by the exhaust conduit.

55. Device as claimed in any of claims 42 through 54, wherein the microphone could have a pass band which is relatively narrow and centered on high acoustic frequencies corresponding to the natural frequency of the wear indicator inserted.

59. Device as claimed in any of claims 42 through 58 wherein it comprises the means appropriate for processing the signal described in the preceding claims;

in particular

Electronics

the device as claimed in the invention has means for electronic processing and the means for connection to this electronic processing means, which could be a dedicated system (84 bit microprocessor, or preferably 8 bits, 16 bits or the technical equivalent) or be integrated in an existing computer or on the other hand use the car stereo, the telephone dedicated to the vehicle, or any other current (or future) electronic system capable of incorporating a microphone (or any other sensor capable of performing the same function) and consequently having electronics suited for acquisition and optionally processing of acoustic signals, and

in the case of a dedicated computer, this should preferably be comprised of a central integrated circuit package which comprises two electronic stages;

the analog stage which conditions the incoming analog and digital signals, contains the power supply card as well as the card for conditioning outgoing signals.

the digital stage, which is computer-based and which performs all processing.

61. Device, according to one of the claims 42 to 59, characterized in the fact that it is adapted to be snow chains and/or spikes detector or equivalent device detector made to increase the mobility, and in the fact that it monitors the presence or the absence of snow chains, or spikes or equivalent devices using means such as described in the previous claims and detecting the acoustic signal generated by snow chains or spikes, or similar devices

this acoustic signature being a function of the geometry and arrangement of the chains, studs or device used (radial, cellular, with a variable number of hoops . . . ),

and detects, in particular, the generating of an acoustic signature of the wheel revolution harmonics.

62. Snow chains, spikes, and similar devices, characterized in the fact that they are designed to generate a particular vibratory signature (for example wheel round harmonic vibration centered on one or several harmonic frequencies included among the 1^st and the 64^th), the detection being then preferentially made on harmonics generated or according to the predetermined setting up, as according to one of the claims 42 to 61.

66. “

Vehicles”

(in the broader sense, that is vehicles, mechanical components, etc.) wherein they are equipped with at least one “

tire”

(in the broad sense again, that is, tire or tread or wear surface or area such as a floor, rotating or otherwise moving mechanical part, etc.) equipped with at least one device as described above (including, as indicated above, devices which are adapted, mutatis mutandis, to the different applications).