WO2022058990A1

WO2022058990A1 - Device for checking the wear of a tyre

Info

Publication number: WO2022058990A1
Application number: PCT/IB2021/058591
Authority: WO
Inventors: Leonardo Terziani
Original assignee: Leonardo Terziani
Priority date: 2020-09-21
Filing date: 2021-09-21
Publication date: 2022-03-24

Abstract

Described is a device (1) for checking the wear of a tyre wheel (101) of a vehicle comprising at least one preformed element (2) made of different material from the tread (102). The preformed element (2) is immersed in the tread (102) at a predetermined height relative to the bottom (102b) or the outermost surface (102a) of the tread (102) and is designed to be in contact with the ground following the wear of the tread (102).

Description

DEVICE FOR CHECKING THE WEAR OF A TYRE

DESCRIPTION

Technical field

This invention relates to a device for checking the wear of a tyre mounted on a wheel of a vehicle.

Background art

All motorcyclists and automobile drivers have at least once encountered the problem of whether and when to replace the tyres mounted in their own vehicle.

There are basically two factors affecting the life of vehicle tyres: the conditions of use and the state of storage before purchasing. However, other variables must also be taken into consideration, such as the mode of loading the vehicle, maintaining the correct pressure of the tyres, but also the average speed of travel, the type of road travelled along, the frequency of impacts suffered, and exposure of tyres to environmental variations.

In view of the variability of the wear to which the tyres are subjected, it is therefore not possible to establish in advance how often to change the tyre.

In order to control the wear of the tyres it is necessary to observe the tread, that is to say, the part of the tyre of a wheel in direct contact with the asphalt where all the forces are exchanged with the ground, controlling the grooves, the colour of the tyre and its imperfections.

According to European regulations, the vehicle tyres must be changed must occur when the tread has reached a depth of 1 .6 mm.

To control this dimension, a rubber plug is normally used, with a depth of 1.6 mm, placed on the tread: when the latter reaches the level of the indicator, it means that the tyre must be changed. Alternatively, it is also possible to use a depth gauge, available in all car spares shops, which measures exactly the depth of the tread grooves at two or more points.

However, not everyone has familiarity with this operation and it cannot be taken for granted that a plug for tyres or a depth gauge is readily available. i For this reason, many people use a one euro com for summer tyres and a two euro coin for winter tyres, checking whether the outer edge is visible or not (if it is visible then the tyre is worn).

Obviously, this is a homemade method and it is therefore an imprecise and improvised remedy.

Summary of the Invention

The aim of the invention is to overcome the above-mentioned drawbacks of prior art types of tyre by providing a device for checking the wear of a tyre which allows continuous assessment of the state of the tyre, not at the request of the user, which is both objective and immediate.

In the context of the above-mentioned purpose, one aim of the invention is to provide a device for checking the wear of a tyre which can be easily used and can be interconnected with the vehicle on which the tyre is mounted.

Another aim of the invention is that the device is reliable and does not create dangerous or risky situations for the safety of the user and of third parties.

Yet another aim of the invention is to provide a device for checking the wear of a tyre with means which are readily available on the market and using materials of common use, in such a way that the device is economically competitive.

This purpose, as well as these and other aims, which are described in more detail below, are achieved by a device for checking the wear of a tyre according to the invention, comprising the technical features described in one or more of the appended claims. The dependent claims correspond to possible different embodiments of the invention.

In particular, according to a first aspect, the invention relates to a device for checking the wear of a tyre of a vehicle wheel which comprises at least one preformed element made of a material different from the rubber of the tread, preferably having similar deformation characteristics, immersed in the tread at a predetermined height relative to the bottom or relative to the outermost surface of the tread.

Obviously, the predetermined height corresponds at least to the dimension of minimum wear of the tread provided for by the current regulations.

The preformed element is designed to be in contact with the ground following wear of the tread, that is to say, when the portion of the tread which wears brings to the surface the outermost face of the preformed element.

Advantageously, in order to prevent an asymmetrical wear of the tooth of the tread from keeping hidden a portion of the preformed element, this will have a dimension which extends for the entire width of the tooth: from groove to groove.

A second aspect of the invention relates to the fact that the preformed element is designed to be heated by friction differently to said tread, in such a way that the temperature measured by measurement means (connected, for example, to the frame of the vehicle or to the rim of the wheel) at the preformed element produces a local anomaly relative to the thermal distribution on the tread.

The preformed element is a metallic component or other conductive material, completely isolated inside the tread and connected to thermal sensors by a wire made of conductive material or directly in contact with its body.

According to another application, it forms a metal grille connected to thermal sensors or visible to an optical thermal scanner which detects the overheating of the tyre.

Obviously, the invention also operates if the preformed element is made of an extremely refractory material which maintains a lower temperature than the tread during use and which in any case produces an anomaly which can be measured by the thermal measurement means.

Advantageously, said measurement means comprise resistant means on one side, in thermal contact with the preformed element, and connected, on the other side, to an electricity generator mounted on the rim of the wheel. The resistant means are made of a particular material, that is to say, designed to significantly vary its resistance value with the temperature.

In this way, for example, a significant heating of the preformed element by friction will correspond to a high level of heating of the resistant means and, consequently, a sudden decrease in the intensity of current passing through the dipole of the generator.

Alternatively, the measurement means comprise a thermocouple or at least one optoelectronic sensor facing towards a point of the preformed element.

According to another embodiment, the preformed element advantageously has at least two protruding elements thermally in contact with it. The two protruding elements, which may be electrical wires passed through by a current generated by electricity supply means, such as a battery, form an electric circuit (preformed element, wires and power supply means); depending on the thermal expansion of the wires (and therefore depending on the heat by which the preformed element is struck), the wires can pass from a position of mutual contact, in which the current passes from one end of them to the other closing the electrical circuit, to a position in which they are spaced apart and the current is not allowed to pass inside the circuit (and vice versa, from normally closed to open circuit).

A last aspect of the invention is due to the fact that the preformed element is made, on the other hand, with a material such as to generate a distinctive sound for the user, for example a whistle, once the tread is worn and the outermost face of the preformed element is brought into contact with the ground.

For the Applicant, the protection is also extended to a complete wheel (that is to say, comprising the rim and the tyre) equipped with the device for checking the wear according to the invention, as well as a vehicle equipped with such a wheel. Description of the drawings

Further features and advantages of the invention are more apparent in the detailed description below, with reference to a preferred, non-limiting embodiment of the device for checking the wear of a tyre, illustrated by way of example and without limiting the scope of the invention, with the aid of the accompanying drawings, in which:

Figure 1 is a cross section of the wheel 101 which is substantially normal relative to its central axis 110 and which contains the central axis 110;

Figure 2 is an enlargement of the cross section of Figure 1 ;

Figure 3 is a cross section of the wheel 101 substantially normal relative to the central axis 110, but not containing the central axis 110;

Figure 4 is a perspective view of a particular shape of the preformed element 2 in the form of a grid;

Figure 5 schematically illustrates a cross section of the wheel 101 which is substantially normal relative to its central axis 110, wherein the device 1 is equipped with the heating element 6;

Figure 6 schematically illustrates a cross section of the wheel 101 substantially normal to its central axis 110, wherein the device 1 is connected to the electrical circuit E supplied by the battery 8.

Detailed description

The above-mentioned drawings show a preferred embodiment of a device for checking the wear of a tyre, according to the invention, which is denoted in its entirety by the reference numeral 1 and which comprises at least one preformed element 2 made of a material different from that of the tread 102 (which is made of rubber). The element 2 is immersed in the tread 102 at a predetermined height relative to the bottom 102b of the tread 102, or relative to the outermost surface 102a of the tread 102, and is designed to make contact with the ground following the wear of the tread 102.

According to a first embodiment, the device comprises means for measuring the temperature connected to the frame of the vehicle or to the rim 107 of the wheel 101 (Figure 1 ).

In this case, the preformed element 2 is designed to be heated by friction differently to said tread 102, in such a way that the temperature measured by said measurement means at said element 2 produces a local anomaly relative to the thermal distribution on the tread 102.

The preformed element 2 is therefore made of a particularly conductive material, for example made of metal, or highly refractory, for example wood or ceramic: in one way or the other, the temperature which will be reached following the heat produced by friction with the ground (when the tread 102 wears sufficiently to allow its contact) is significantly different from the temperature which can be measured on average in the tread 102. According to a first variant embodiment, the preformed element is a component completely isolated from the tread 102, for example a plug, a sheet-like portion or a globular body.

As mentioned, the wear of the tread 102 at a certain point causes the contact between the outermost face of the preformed element and the ground.

If the preformed element is made of conductive material, a thermocouple or another type of thermal measurement sensor connected to it and installed on the rim 107 will detect the overheating relative to the tread 102.

According to another variant, there is a set of preformed elements 2 which are reciprocally connected thermally.

Preferably, the preformed elements 2 are connected by transversal elements 4, which extend axially relative to the wheel 101 , for connection to a supporting frame 5 immersed in the belt 104 of the tyre mounted on the wheel 101 (Figure 2).

Preferably, both the circular elements 3 and the transversal elements 4 are made of a metallic material.

With reference to Figures 2 and 3, the preformed elements 2 are, for example, concentric circular elements 3, with each centre coinciding with the geometrical centre C of the wheel 101 , so as to form a sort of metal grid (Figure 4).

With reference to Figure 2, each circular element 3 consists of a metal plate 3 which extends along a closed line, whilst the transversal elements 4 all comprise a wire or a metal plate 4.

According to a first embodiment, the measurement means are made by thermal sensors, that is to say, thermocouples. The thermocouples are preferably each positioned in a circular element 3 different from the above- mentioned series.

Obviously, the thermocouples may be connected to the frame 5 and positioned on the rim 107 of the wheel 101 .

Other means for measuring the temperature comprise resistant means, such as a thermistor 6, of per se known type, comprising a portion in thermal contact with the preformed element 2 and connected, on the other side, to an electricity generator 7 by two wires 7' and 7" (Figure 5). The generator 7 is mounted on the rim 107 and may also be the one used to power the current tyre pressure sensors. The thermistor 6 is made of a material designed to significantly vary its resistance value with the temperature. In this way, a high thermal gradient causes a significant increase in the resistance and, consequently, a significant reduction in the intensity of current flowing through the electric dipole of the generator 7.

It will therefore be sufficient to keep under control the intensity of current measured at the dipole (which during normal operation will be within a predetermined range) to be immediately aware that, once the intensity suddenly drops on the basis of the known features of the thermistor, the temperature to which the friction has brought the preformed element 2 is clearly greater than that present during normal operation, that is to say, the element 2 has come into contact with the asphalt and therefore the thickness of the tread 102 is approaching the limit planned for it to be changed.

According to an alternative embodiment, the measurement means comprise a set of thermal optics (for example, of the infrared type) facing towards the tread of the tyre and anchored to the frame of the vehicle (for example, to the wheel-holder unit).

Once the preformed element 2 comes into contact with the ground, a local thermal anomaly is generated (the temperature thereof, as mentioned, becomes much higher than that of the tread 102) which can be detected by the thermal camera, for example by different video colours.

The structure of the preformed elements 2, as well as the positioning of these sensors is not limiting, since the distribution of heat in the elements 2 is substantially uniform, whether they are made of conductive or insulating material, especially during a period of time such that it can be considered negligible: consequently, the transmission of heat can be considered instantaneous.

Alarm means are advantageously provided designed to communicate with the user of the vehicle. These pass from a passive position, in which they are inactive, to an active position, in which they communicate with the user, depending on whether the temperature measured by the measurement means does not exceed or exceeds a preset threshold value.

If the thermistor 6 is used, the calculation of the threshold value can be easily processed by knowing how the thermistor 6 itself acts with the temperature and therefore setting the Ohm law (which links the value of the current intensity to the resistance, under equal conditions of voltage present in the circuit).

In any case, the measurement means are advantageously connected to alarm means which communicate when necessary with the user of the vehicle: in fact, they are passive and therefore inactive (that is to say, are not in communication with the user) when the temperature measured does not exceed a preset threshold value. When, on the other hand, the threshold value is exceeded, the alarm means activate and communicate with the user, alerting the user of the wear of the tyre (for example, via a remote wireless signal sent to the vehicle control unit).

The threshold value will be suitable for the type of vehicle on which the tyre is mounted, and in any case such as not to allow the false positives for the system, therefore, reasonably higher than the normal operating temperature of the tyre (between 50°C and 80°C in common cars) but not too far from that value so as not to risk that one or more of the preformed elements 2, in contact with the asphalt, overheats excessively causing damage to the vehicle.

As shown in Figure 6, according to another means of checking the wear, the preformed element 2 advantageously has at least two protruding elements 8' and 8" (electrical wires), thermally in contact with it. The two wires 8' and 8" are designed to be passed through by a current generated by electricity supply means, that is to say, by a battery 8 - preferably integral with the casing 107 - in such a way that, depending on their thermal expansion, they can pass from a position of mutual contact, in which the current passes from one end of them to the other by closing the electrical circuit E formed by the electric battery 8 and the preformed element 2, to a position in which the wires 8' and 8" are spaced and the passage of current inside the circuit E is not allowed.

According to this embodiment, the alarm means are replaced by signalling means which alert the user of the vehicle when the electric circuit E (formed by the preformed element 2, by the wires 8' and 8" and by the battery 8 is closed and/or opened.

For example, if due to the friction generated by the contact with the asphalt, the preformed element 2 heats up, the wires 8' and 8", in contact with the latter, will expand, causing the closing of the electrical circuit E of Figure 6: the electrical contact will cause an electrical signal designed, by the amplification of the alarm means, to alert the user of the wear of the tyre.

The geometry of the wires 8' and 8", as well as their resistivity, makes it possible to calibrate a temperature threshold value such as to close (or, in another embodiment, open) the circuit E.

In practice, during regular use, each element 2 is immersed completely in the tread 102 and is never in contact with the asphalt; for this reason, the heat which it stores it is substantially the one supplied by the tyre and, consequently, the temperature measured by the measurement means is below the preset threshold value.

For example, under standard conditions, the threshold value will be set at 120°C, whilst the tread 102 reaches a maximum temperature of approximately 80°C.

When the tread wears, the outermost face of the elements 2 is gradually uncovered and, in contact with friction of the asphalt, it quickly overheats and reaches a temperature higher than that of the threshold value.

The alarm means or signalling means, such as a warning light in the dashboard of the vehicle, promptly alert the driver that the tread is wearing and that the tyre must be quickly changed.

According to an alternative embodiment, the preformed elements are made of a material such as to generate a distinctive sound for the user, in contact with the ground.

For example, preformed elements made of composite or plastic material, advantageously suitably shaped, produce in contact with the asphalt a characteristic whistle which, amplified if necessary by the skeleton of the vehicle which acts as a harmonic casing, warns the user of the wear the tyre is approaching.

Advantageously, a suitable shaping of the preformed elements makes the sound customisable and therefore even more distinctive to the user's ear.

It is imaginable that if the limit of use of the tread is 1.6 mm, the plate is positioned at 1.8 mm, so as to allow the user to change the tyres in a convenient fashion.

From the above description it may be seen how the invention achieves the preset purpose and aims and in particular the fact that a device is made for checking the wear of a tyre which allows an immediate and objective io assessment of the state of the tyre.

In particular, the alarm means immediately alert the user of the need to change the tyre, even if the user has not posed the problem due to carelessness, negligence or ignorance.

Another advantage of the invention is due to the fact that such a device is simple to use and is easily mounted on the vehicle in which the tyre is mounted, if necessary, by interconnecting with the computer onboard the vehicle.

Moreover, thanks to correct calibration of the means for measuring the temperature of the preformed element which, by overheating, reaches a much higher temperature than the tread of the tyre (or much lower), there is a reliable means for checking the state of the tyre, without putting the vehicle and its passengers in a condition of danger or risk.

Another advantage of the invention is due to the fact that, according to the version in which the preformed element generates an alarm sound, there is no need to adopt sensor means or electronic systems for warning the user, with a considerable saving in terms of production of the tyre, fitting and maintenance of the vehicle.

Lastly, the use of means which are easily available on the market and the use of common materials makes the device economically competitive.

The invention can be modified and adapted in several ways without thereby departing from the scope of the inventive concept.

Moreover, all the details of the invention may be substituted by other technically equivalent elements.

In practice, the materials used, as well as the dimensions, may be of any type, depending on requirements, provided that they are consistent with their production purposes.

Claims

1) A device (1 ) for checking the wear of a tyre of a wheel (101 ) of a vehicle, comprising at least one preformed element (2) made of different material from the tread (102), immersed in the tread (102) at a predetermined height relative to the bottom (102b) of said tread (102), or relative to the outermost surface (102a) of said tread (102) and designed to be in contact with the ground following the wear of said tread (102).

2) The device (1 ) according to the preceding claim, wherein a dimension of said preformed element (2) extends substantially to the same distance between two adjacent grooves of said tread (102).

3) The device (1 ) according to claim 1 or 2, wherein said preformed element (2) is completely isolated inside said tread (102).

4) The device (1 ) according to any one of the preceding claims, comprising a series of said preformed elements (2) which are reciprocally connected thermally.

5) The device (1 ) according to the preceding claim, wherein said preformed elements (2) are connected by transversal elements (4), extending axially relative to the wheel (101 ), for connection to a supporting frame (5) immersed in the belt (104) of said tyre.

6) The device (1 ) according to any one of the preceding claims, comprising means for measuring the temperature connected to the frame of the vehicle or to the rim (107) of the wheel (101 ), said preformed element (2) being designed to be heated by friction differently to said tread (102), in such a way that the temperature measured by said measurement means at said element (2) produces a local anomaly relative to the thermal distribution on said tread (102). 7) The device (1) according to the preceding claim, wherein the measurement means comprise resistant means (6) on one side, connected thermally to said preformed element (2) and connected, on the other side, to an electricity generator (7) mounted on said rim (107), said resistant means being made of a material such that it is designed to vary significantly its resistance value with the temperature in such a way that a high thermal gradient corresponds to a significant increase in the resistance of said resistant means (6) and, consequently, a significant reduction in the intensity of current flowing through the electric dipole of said electricity generator (7).

8) The device (1 ) according to claim 6 or 7, wherein said measurement means comprise at least one optical temperature sensor facing towards said tread (102).

9) The device (1 ) according to any one of claims 6 to 8, comprising alarm means designed to communicate with the user of the vehicle and designed to pass from a passive position, in which they are inactive, to an active position, in which they communicate with the user, depending on whether the temperature measured by said measurement means respectively does not exceed or exceeds a preset threshold value.

10) The device (1 ) according to any one of the preceding claims, wherein said preformed element (2) comprises at least two thermally protruding elements (8', 8") in contact with it and designed to be passed through by a current generated by electricity supply means (8), in such a way that, depending on their thermal expansion, they are designed to pass from a position of mutual contact in which the current passes from one end of them to the other, to a position in which said protruding elements (8', 8") are spaced from one another, which does not allow the passage of current, or vice versa.

11 ) The device (1 ) according to the preceding claim, comprising signalling means for the user of the vehicle of the closing and/or opening of the electric circuit (E) formed by said preformed element (2), said at least two protruding elements (8', 8") and said electricity supply means (8).

12) The device (1 ) according to claim 1 or 2, wherein said preformed element is designed to generate a distinctive sound for the user, in contact with the ground.

13) A wheel (101 ) for a vehicle comprising a device (1 ) for checking the wear, according to any one of the preceding claims.

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