RU2801670C2 - Tire with monitoring device - Google Patents

Abstract

FIELD: automotive industry.

SUBSTANCE: tire (11) having an inner surface (111) is provided with at least one monitoring device (3) glued to the inner surface (111). The monitoring device (3) is made on a flexible substrate, and the adhesion of the flexible substrate to the inner surface (111) is achieved by means of an element (4) to eliminate interference placed between the specified at least one monitoring device (3) and the inner surface (111) of the tire (11).

EFFECT: increased reliability of mounting the monitoring device to the tire.

15 cl, 4 dwg, 6 tbl

Description

Technical field

The present invention relates to a tire provided with a monitoring device, for example a device comprising a pressure sensor and/or a temperature sensor and/or an acceleration and/or deformation sensor, on the inner surface of the tire.

State of the art

For a long time, there has been a need to monitor the condition of a tire during operation on a motor vehicle and to determine the characteristic parameters that characterize its operating condition both under static conditions and especially when the vehicle is in motion, in order to improve the safety of motor vehicles.

The tire parameter that can be monitored is the tire's internal pressure. A tire that is not properly inflated can result in higher fuel consumption, reduced vehicle agility, and uneven tire wear, to name but a few of the more important problems. Consequently, systems have been developed to monitor tire inflation pressure during operation, these systems informing the driver of any pressure drop and consequently the need to restore the optimum condition to correct the aforementioned problems.

Another parameter that can provide very important information about the condition of a tire during operation is tire temperature. An abnormal rise in temperature is a sign of a critical operating condition that can cause permanent tire damage. In addition, since temperature affects pressure, temperature measurement allows you to recalculate the instantaneous measured pressure value to monitor its renormalized value at room temperature.

WO 2004110794 A1 describes a tire provided with a monitoring device bonded to the inner surface of the tire. The monitoring device described was of a rigid type (i.e., made on a rigid printed circuit board or printed circuit boards) in contrast to the tire, which instead exhibits dynamic behavior with continuous and cyclic deformations. The rigidity of the monitoring device is due to the need to ensure that the welds to the board, the metal tracks through the boards, and the integrated circuits themselves do not collapse due to bending.

The problem that arose related to making a reliable and stable connection between the tire and the rigid monitoring device, since the radial mechanical stresses arising from the rotation of the tire during operation caused the rigid device to detach. The proposed solution was to place at least one layer of damping material having a Shore A hardness (measured at 23°C according to ASTM D2240 (American Society for Testing and Materials)) ranging from about 1 to about 40, and elastic recovery ( measured at 23°C according to ASTM D1054) less than about 60 between the inner surface of the tire and the monitoring device.

In recent years, technologies have emerged for the use of electronic means based on flexible and/or extensible substrates made, for example, by means of organic and inorganic semiconductors and/or flexible plastics.

Monitoring devices have been proposed made on flexible or even stretchable substrates for installation inside a tire or on a rim, as described, for example, in US 4862486 A, US 2007013503 A1, US 2010271191 A1, US 2014118134 A1 and US 2015097662 A1.

The essence of the invention

The Applicant has recognized that the provision of monitoring devices on flexible substrates to be attached to the inner surface of the tire may be particularly advantageous for various reasons. First of all, these substrates are usually very light: this allows the weight of the monitoring device to be reduced compared to an equivalent device made on a rigid printed circuit board, resulting in the advantages of less unbalance occurring in the tire during rotation, less impact of loads transmitted to the device itself in the radial direction, the possibility of attaching the device itself to the inner surface of the tire using simple pressure-sensitive adhesives (PSA). In addition, the flexibility of these devices had to allow the devices themselves to naturally adapt to the deformations that the tire itself undergoes during rotation, in contrast to devices made on rigid printed circuit boards.

However, the Applicant was satisfied that this idea was too simplistic.

In particular, Applicant has performed a long series of tests with tires containing monitoring devices made on flexible substrates, tensile or non-extensible, attached to the inner surface of the tire, and found that these devices have various stability and/or durability problems with over time under different tire operating conditions.

For example, Applicant has become aware that monitoring devices made on flexible and extensible substrates can be subject to damage, such as destruction of the wiring circuits between the components of the device itself.

From the fatigue resistance tests carried out on tires, the Applicant also ascertained that devices made on flexible substrates had various problems depending on whether such substrates were also extensible or not.

In particular, the Applicant found from observation that devices made on flexible but inextensible substrates (e.g., polyimide and polyethylene naphthalate) retained the conductivity of the connection circuits between the various components of the device, but exhibited poor adhesive bonding, with numerous and noticeable detachments from the internal tire surface; on the other hand, devices made on flexible as well as extensible substrates (eg, polyurethane) have shown good adhesive adhesion, but conduction failures due to disruptions and/or breaks in the electronic circuit's conductive tracks.

In addition, the Applicant satisfied that even the use of tensile pastes to create conductive tracks on flexible and tensile substrates could not solve the problem of their destruction and/or rupture, which also occurred when tested on high-speed tires.

Through the analysis of the results obtained from a long series of experimental tests, the Applicant has formulated some hypotheses relating to the observed problems.

Without wishing to be bound by any explanatory theory, the Applicant believes that the millions of cycles to which a monitoring device, made on a flexible substrate, tensile or inextensible, attached to the inner surface of the tire, is subjected to during rotation of the tire under various operating conditions (speeds, load, etc.), lead to the creation of forces of different nature and magnitude acting on the device itself.

In particular, the Applicant has established from observations that during the passage in the contact zone, the device is subjected to cyclic resultant forces in the longitudinal (as well as lateral) direction due to the deformation that the tire undergoes during rotation in contact with the road.

For example, the device is subjected to cycles of stretch/elongation and compression/shortening as it enters and exits the contact patch area due to deformations of the tire inner surface.

Monitor device components can also contribute to the aforementioned complex cyclic stresses to which the device itself is subjected, due to the inertial forces caused by the masses of these components when subjected to changes in speed in the longitudinal (as well as lateral) direction that occur when the monitoring device enters the contact patch and exit from it.

The Applicant believes that the problems observed in the above tests may be largely due to repetitive shear stresses arising from the resultant cyclic forces generated in the longitudinal and lateral directions. However, these voltages did not cause much harm to monitoring devices made on rigid printed circuit boards, which were believed to be more affected by significantly higher stresses in the radial direction.

Therefore, the Applicant has suggested that it would be beneficial to reduce the transmission of longitudinal and lateral shear stresses/loads, in particular in the area of the connection between the tire and the device, which could cause disconnections and/or destruction of the conductive tracks.

For example, the Applicant has found that the use of an acrylic double-sided adhesive tape containing a viscoelastic acrylic foam resistant to dynamic shear stresses has made it possible to obtain good adhesive adhesion of a monitoring device made on inextensible flexible substrates to the inner surface of a tire.

Through further experimentation, the Applicant has additionally found from observation that the best results have been obtained using a thin but not negligible thickness of the double-sided adhesive tape, for example between 0.4 and 2.4 mm.

Subsequently, the Applicant additionally established from observation that good results with regard to the adhesive adhesion of a monitoring device made on inextensible flexible substrates to the inner surface of the tire could be obtained with thick and soft adhesives and/or with a foamed polymeric material (or even a material in the form of a gel). ), such as ethylene-propylene-diene monomer rubber (EPDM) or polyurethane, which is suitably double-sided by layers of acrylic adhesive deposited on its surface.

Therefore, the first aspect of the present invention relates to a tire having an inner surface and provided with at least one monitoring device adhered to this inner surface, such a monitoring device being made on a flexible substrate (preferably inextensible), and the adhesive adhesion of said flexible substrate with a given inner surface is achieved by means of an anti-interference element placed between said at least one monitoring device and said inner surface of the tire.

Such a decoupling element is capable of withstanding, in particular, dynamic complex shear stresses which are generated (in different directions) due to the cyclic deformation to which the tire is subjected in the area of the contact patch. In practice, it appears to act like a substrate that withstands given shear stresses such that it deforms (e.g., stretches and/or shortens) cyclically without failure to reduce or eliminate stresses imparted to the flexible substrate and caused by internal surface deformations, and/or withstands stresses transmitted by the flexible substrate and generated by inertial forces due to the masses of the monitoring device components. This advantageously also allows the use of inextensible substrates more suitable for adequately protecting the integrity of the electrically conductive paths connecting the various components of the monitoring device. In addition, this made it possible to obtain an excellent state of adhesive adhesion of the monitoring device to the inner surface of the tire without significant separation.

Said anti-interference element may be a double-sided adhesive tape containing (i) a viscoelastic acrylic foam or (ii) a polymeric foam backing (or even in the form of a gel) such as ethylene-propylene-diene monomer (EPDM) rubber. ) or polyurethane, or (iii) at least one layer of acrylic adhesive with a thickness equal to or greater than 0.4 mm, or (iv) a combination of the above, wherein said double-sided adhesive tape is resistant to dynamic shear stress (for example, measured according to ASTM D-1002) greater than 50 kPa, preferably greater than 150 kPa, for example between 50 and 3000 kPa.

In accordance with another aspect, the present invention relates to a method for mounting a monitoring device made on a flexible substrate (preferably inextensible) on a tire having an inner surface of a substantially toroidal shape, the method comprising:

- selection of the area of the inner surface of the tire, on which it is desirable to install the monitoring device;

- providing adhesive adhesion between the specified flexible substrate (preferably inextensible) and the specified area of the inner surface of the tire;

wherein said adhesive grip is provided by means of an interference elimination element positioned between said flexible substrate and said portion of the tire inner surface.

Detailed description of the invention

In the present description and in the following claims, the expression "monitoring device" means any electrical, electronic or piezoelectric device capable of measuring and/or processing and/or storing and/or transmitting to an external device (for example, a fixed device on a vehicle , or a mobile device, such as a smartphone, or a device located at a location passed by said vehicle) of at least one tire performance parameter in digital or analog form.

The characteristic parameter may be an instantaneous value or a time-averaged value and may refer to:

- operating parameters of the tire, for example, the internal pressure in the tire and/or the internal temperature of the tire or any of its parts (see, for example, US 5540092, US 5900808 and US 5562787); and/or

- data relating to the dynamic characteristics of the tire, for example, acceleration or displacement of any point of the tire in at least one direction selected from the direction from the periphery to the center, the longitudinal direction and the lateral direction (see, for example, patents EP 887211, WO 01/ 36241 and US 6204758); and/or

- data relating to the forces of interaction between the bead and the rim; and/or

- data relating to the identification of the tire, such as manufacturing or uniformity data (see, for example, US Pat. No. 6,217,683).

Therefore, the monitoring device may comprise an electronic unit containing at least one sensor for measuring at least one tire characteristic parameter (for example, a pressure sensor, a temperature sensor, an accelerometer, a motion sensor, a strain sensor, or a speed sensor) and/or an electronic memory device. , which contains bus identification data (for example, a chip or transponder) and at least one transmitter for transmitting measurement data to an external device.

The monitoring device may further comprise at least one power supply device. The term "power supply device" means a component which is designed to supply power to an electronic unit and which may contain one or more batteries in which the energy to be supplied is stored in advance (for example, batteries or capacitors), or may contain a power generator and / or a device for receiving electricity on site, made (made) with the possibility of supplying power directly to the electronic unit and / or with the possibility of recharging the batteries (for example, an energy recovery device or a “collecting or capturing energy” device, or a device for inductive charging).

The power supply device may preferably comprise one or more electric power banks, more preferably two to four electric power cells, and even more preferably two electric power cells.

The electronic unit and the power supply device are fixed on the flexible substrate of the monitoring device and are electrically connected by means of a wiring diagram.

The wiring diagram is preferably fixed on a flexible substrate, more preferably formed by printing on said flexible substrate with a conductive paste, even more preferably formed by screen printing/grid printing, lithographic printing, inkjet printing, etc. In one embodiment, the electrical wiring diagram contains copper conductive tracks, preferably obtained by chemical etching of a thin layer of copper (for example, with a thickness of several tens of microns). These technologies are particularly suitable for flexible substrates and provide the ability to create bend-resistant conductive tracks.

The flexible substrate can be made with an elastomeric or thermoplastic material that is resistant to operating temperatures expected for a tire, typically over a wide range, which can vary from about -40°C in winter use to about 150-160°C in outdoor use. sports cars. More specifically, materials without first and/or second order phase transitions (eg, melting, glass transitions) are preferably used over the temperature range expected for a given use.

In the context of the present description and the following claims, by "flexible substrate" is meant essentially a substrate formed from a material (including a laminate/composite material) which, when used to form a square-shaped sheet with a side substantially larger than that defined in the longitudinal direction circumference, the extent of the zone of entry into or exit from the contact patch of a tire, (for example, boards with a surface area of 120 mm × 120 mm), and with a thickness equal to the thickness of the substrate, makes it possible to adapt the shape of such a sheet - at indoor temperature - to the shape of a cylindrical surface with a radius less than the radius of normal curvature of a tire inflated to its nominal inflation pressure (e.g., a cylindrical surface with a radius of 200 mm, preferably 100 mm, more preferably 50 mm) without breaking or being subject to permanent deformation.

In the context of the present description and the following claims, "inextensible substrate" generally means a substrate with a thickness of from about 10 µm to about 400 µm, preferably from about 50 µm to about 200 µm, made from a material (including a multilayer/composite material) having a tensile modulus preferably greater than 0.1 GPa, more preferably greater than 0.5 GPa at 23°C.

Said flexible substrate is preferably a film of an elastomeric or thermoplastic material selected from nylon, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide and polyurethane material. Silicon foil (or foil/thin sheets of other semiconductors) can also be used. It has been proven that such flexible substrates are suitable for technologies in which electrical connecting tracks are formed by molding or depositing on a substrate or obtained by chemical etching, and prefabricated electronic components are attached by gluing, and the connection between the components and electrical connecting tracks can be formed by using conductive adhesives and/or by soldering with tin or its alloys (for example, an alloy of tin and bismuth).

The flexible substrate is preferably made from materials based on polyimide, polyesterimide, fluoropolymers or polyester, in particular semi-aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and polyethylene naphthalate. Polyimide substrates are commercially manufactured and marketed, for example, by Dupont under the brand name Kapton™. Polyester substrates are commercially manufactured and marketed by Teijin under the brand name Teonex™.

The flexible substrate can be produced in a wide variety of shapes without particular limitations. The flexible substrate may, for example, be square, rectangular, diamond-shaped, circular, or a combination thereof to form specific shapes such as a Z- or M-shape.

The edges of the flexible substrate may be perpendicular, or they may preferably be chamfered, cut or rounded.

The flexible substrate preferably has an elongated rectangular or cigar shape, ie a rectangular shape with rounded edges, similar to that shown in FIG.

Alternatively, the flexible substrate has a Z-shape like that shown in FIG. 3 or a square shape like that shown in FIG.

The dimensions of the flexible substrate are not particularly limited and depend on the dimensions of the electronic unit and the power supply device.

Typically, the dimensions of the flexible substrate are a length of 20 to 150 mm, preferably 40 to 120 mm, and a width of 10 to 90 mm, preferably 20 to 50 mm. The length of the flexible substrate is preferably 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105 or 110 mm. The width of the flexible substrate is preferably 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 or 90 mm.

According to the present invention, the interference elimination element is placed between the monitoring device and the inner surface of the tire.

In particular, the interference elimination member may be an acrylic double-sided adhesive tape. This acrylic double-sided adhesive tape preferably withstands dynamic shear stress (eg measured according to ASTM D-1002) in excess of 50 kPa, preferably in excess of 150 kPa, eg 50 to 3000 kPa.

In the first embodiment, the anti-interference member may be an acrylic double-sided adhesive tape containing a viscoelastic acrylic foam with a thickness equal to or greater than 0.4 mm.

Suitable examples of the anti-interference member of the present invention are 3M™ VHB™ Adhesive Tapes 4941, 4956 and 5952 Family or 3M™ RP45 and RP62 Family Adhesive Tapes or Nitto Hyperjoint Adhesive Tapes H8004-H8008-H8012-H9004-H9008 Family -H9012.

Such tapes consist of a conformal acrylic foam adhesive provided on both sides. An acrylic pressure-sensitive adhesive (PSA) (such as 3M™ 9469, 3M™ 468, 3M™ 93430, or Nitto 5925 Adhesives) may be additionally applied to one or both of the surfaces above to increase adhesion. tapes.

Alternatively, the anti-interference member can be an acrylic double-sided adhesive tape containing a backing of a foamed polymer material (or even a gel material) with a thickness equal to or greater than 0.4 mm, such as, for example, porous ethylene copolymer rubber. , propylene and diene monomer (EPDM) or polyurethane foam, which is made double-sided by layers of acrylic adhesive applied to both surfaces of the base.

Porous rubber based on a copolymer of ethylene, propylene and diene monomer (EPDM) belongs to the family of synthetic rubbers obtained by the copolymerization of ethylene and propylene in the presence of a blowing agent, usually hydrocarbons, CO ₂ or other mixtures.

Similarly, polyurethane foam belongs to a family of polymers characterized by the presence of urethane bonds (-N-CO-O-) and obtained by the reaction of di-, tri-, polyisocyanates carried out in the presence of a blowing agent with a polyol, usually a polyester polyol obtained by polymerization of an epoxy compound, or a polyester polyol. obtained by polycondensation of multifunctional carboxylic acids and polyhydroxyl compounds.

In both cases, a soft spongy material is obtained, containing closed or open pores in its interior and characterized by a density of 10 to 800 kg/m ³ , preferably 20 to 700 kg/m ³ .

Non-limiting examples of porous ethylene-propylene-diene monomer (EPDM) rubber suitable for the purposes of the present invention and available on the market are layers of porous ethylene-propylene-diene monomer (EPDM) rubber manufactured by Tekspan Automotive, for example, such as an EPDM SE30 rubber layer (eg made double-sided with acrylic pressure-sensitive adhesives (PSA) and placed on both surfaces of this layer).

Non-limiting examples of polyurethane foam suitable for the purposes of the present invention and available on the market are layers of polyurethane foam from the Cirene range manufactured by Cires SpA, such as layers of polyurethane foam Cirene 20, 25 and 30 (for example, made double-sided with acrylic adhesives that bond 4004-4008-4016-4026-4032-4052-4056- 4085.

Additional suitable examples of the anti-interference element of the present invention are acrylic double-sided adhesive tape containing at least one layer of acrylic adhesive with a thickness equal to or greater than 0.4 mm, such as, for example, 3M™ adhesive tapes from the Extreme Sealing 4411 family and 4412 double-sided with an acrylic pressure-sensitive adhesive (PSA) (such as 3M™ 9469, 3M™ 468, 3M™ 93430, or Nitto 5925 adhesives).

The thickness of the anti-interference member, including the adhesive layers deposited on its surface, is preferably 0.4 to 2.4 mm, more preferably 0.6 to 2.2 mm, even more preferably 0.8 to 2.2 mm and preferably from 1.0 to 1.8 mm.

Other dimensions of the anti-interference element, namely length and width, depend on the dimensions of the flexible substrate of the monitoring device. The length and width of the anti-interference element is preferably at least equal to the length and width of the flexible substrate of the monitoring device. More preferably, if the length and/or width of the element to eliminate interference exceed respectively the length and/or width of the flexible substrate. The length and/or width of the anti-interference element preferably exceeds the length and width of the flexible substrate respectively by at least 0.5 mm, preferably by at least 2 mm, and more preferably by an amount in the range of 3 to 5 mm.

There are no particular restrictions on the properties of any adhesive used for the anti-interference member, provided that it is resistant to the operating temperatures expected for the tire, generally over a wide range, which, as mentioned above, can cover temperatures from about -40°C in winter use to approx. 150-160°C in sports car use.

A protective layer is preferably added to the monitoring device to cover and protect the components of the device (electronic devices, conductive tracks, batteries, etc.). The protective layer is not particularly limited: films of polymeric material can be used for this purpose, such as a nylon cover layer (Domo™ Filmon™ CSX18 cast nylon film) bonded by lamination with an acrylic adhesive.

The length and width of the protective layer depends on the size of the flexible substrate of the monitoring device. The length and width of the protective layer is preferably at least equal to the length and width of the flexible substrate. More preferably, if the length and/or width of the protective layer exceed respectively the length and/or width of the flexible substrate. The length and/or width of the protective layer preferably exceeds respectively the length and width of the flexible substrate by at least 0.5 mm, preferably by at least 2 mm, and more preferably by an amount in the range of 3 to 5 mm.

The method of the present invention can be applied to any type of tire and can preferably be carried out by the user when replacing old tires with new ones. This is possible because the operation of inserting the device into the tire can be performed simply and quickly, and does not necessarily require it to be performed by specialized personnel.

The portion of the inner surface on which the monitoring device is installed can preferably be selected in an area in which the bending stresses of the tire are relatively low.

In particular, a region in the crown region of the tyre, preferably close to the equatorial plane of the tyre, is preferred. Alternatively, the monitoring device may be mounted on an inner surface area in the bead area of the tire.

The installation of the monitoring device is preferably carried out on a clean area of the inner surface of the tire in the absence of adhesion promoters (or primers). A clean surface area can be obtained, for example, by cleaning with detergents and/or solvents and/or by mechanical action and/or by a laser polishing operation. In another embodiment, the protective film may be placed on the green tire, prior to curing, on the area of the inner surface intended to receive the monitoring device. The protective film keeps this area of the inner surface of the tire substantially free from release agent contamination (or in any case from contamination or unwanted substances from the vulcanization process) and the protective film is then removed after the vulcanization process before the monitoring device is installed. Such a film may be made from a material that is resistant to the temperature and pressure operating conditions typical of the vulcanization process, such as nylon or polyester, for example.

Additional features and advantages will become apparent from the detailed description of preferred but non-limiting embodiments of the present invention.

This description is given below with reference to the accompanying drawings, in which:

1 is a cross-sectional view of a tire mounted on a supporting rim intended for it and provided with a monitoring device mounted on the inner surface of the tire according to the invention; And

2-4 are schematic plan views of respective embodiments of a monitoring device used in the present invention.

1 shows a wheel comprising a tire 11 of the type commonly known as "tubeless", in other words a tubeless tyre, and a supporting rim 12. This tire is inflated by means of an inflation valve 13 located, for example, in a groove of said rim.

Tire 11, a schematic representation of which is shown in figure 1, has an internally hollow, toroidal structure formed by a plurality of components. The frame structure 16 with metal or textile cords has two beads 14 and 14', each of which is formed along the inner circumferential peripheral edge of the frame structure 16 for fixing the tire 11 relative to the corresponding support rim 12 of the wheel. Each of the beads 14 and 14' contains at least one annular reinforcing core 15 and 15', known as the bead core.

The frame structure 16 is formed by at least one layer of the frame, which contains textile or metal cords extending in the axial direction from one bead 14 to the other bead 14' with a toroidal profile, and which has ends, each of which is connected to the corresponding core 15 and 15 ' side. In radial tires, the aforementioned cords are located essentially in planes containing the axis of rotation of the tire.

An annular structure 17, known as a belt structure, usually formed by at least one layer of metal or textile cords embedded in an elastomeric material, is located on the crown region of the carcass structure 16. The belt structure 17 typically comprises two belt bands (not shown in FIG. 1), which include a plurality of reinforcing cords, typically metal cords, which are parallel to each other in each band and cross with respect to the cords of an adjacent band, being oriented so as to form a predetermined angle with respect to the circumferential direction. It is possible, if necessary, to impose at least one additional reinforcing layer (not shown in figure 1) on the breaker tape, the most distant from the center in the radial direction, while the specified additional layer is formed by including a plurality of reinforcing cords, usually textile cords, located at an angle of several degrees with respect to the circumferential direction, coated and joined together by an elastomeric material.

At a radially outward position with respect to the belt structure 17, a tread band 18 is applied, which is formed from an elastomeric material and usually has a tread pattern on the outermost surface in the radial direction and is intended to contact the tire with the road during rolling.

In addition, two sidewalls 19 and 19' of elastomeric material, each extending radially outward from the outer edge of the respective bead 14 and 14', are located on the frame structure at axially opposite side positions.

In tires of this type, which are known as tubeless, the inner surface of the tire is usually covered with a sealing layer 111, that is, at least one layer of airtight elastomeric material. Finally, the tire may contain other known elements, such as additional reinforcing elements, rubber fillers, etc., in accordance with the specific tire model.

In general, the tire monitoring system typically comprises a fixed device, preferably located on the vehicle on which the tire is mounted, and a mobile device, i.e. a monitoring device 3, containing a sensor and interacting with the surface of the sealing layer 111 of the tire 11, as shown in Fig.1, through element 4 to eliminate interference.

As illustrated in FIGS. 2-4, the monitoring device 3 comprises at least one electronic unit 11 containing a sensor S for measuring at least one tire characteristic parameter (for example, pressure, temperature, acceleration, deformation, etc.), a transmitter T for transmitting data to the fixed device and a power supply device containing at least one battery 34 and designed to supply electricity to the electronic unit 31.

As an example, the sensor may be a model FXTH870911DT1 sensor sold by NXP Semiconductors®, capable of detecting all three physical quantities: temperature, pressure, and acceleration, in particular at least the radial component and the tangential component of acceleration.

As an example, the transmitter T may be a Bluetooth transceiver model SmartBond DA1458 sold by Dialog Semiconductor®.

2-4 show two batteries 34, but the monitoring device 3 can also contain only one battery 34 or even more than two batteries, for example three or four batteries, arranged symmetrically with respect to the electronic unit 31.

By way of example, the batteries 34 may be electric batteries, such as the CR2032HR button cell sold by Maxell® (capacity 200 mAh, weight 3 g, diameter and thickness 20×3.2 mm) or BR1632A sold by Panasonic® , (capacity 120 mAh, 1.5 g, 16 × 3.2 mm). Typical voltage is approximately 3V and operating temperatures range from -40°C to +125°C.

The electronic unit 31 and the batteries 34 are electrically connected via the wiring diagram 32 shown schematically in FIGS. 2-4.

In one embodiment, the traces of the wiring diagram 32 are formed by a conductive paste (e.g., DuPont® 5025 silver conductive paste) screen printed directly onto the flexible substrate 33.

The electronic unit 31 and the battery or batteries 34 are placed and adhered to the flexible substrate 33, for example with a conductive adhesive (eg Henkel 3104 WXL) and a structural adhesive (eg Henkel A312).

In the embodiment shown in figures 2 and 3, two batteries 34 are located on opposite sides of the electronic unit 31.

For example, in the embodiment of FIG. 2, the dimensions along the longitudinal direction and along the orthogonal direction (in the plane of FIG. 2) may be 110×30 mm or 80×25 mm. The distance D between two accumulators 34 is approximately 70 mm in the case of dimensions 110×30 mm, while with dimensions equal to 80×25 mm, the distance D is approximately 50 mm.

In the embodiment shown in FIG. 4, the monitoring device 3 has a plane (e.g. defined by the plane of the flexible substrate 33) with an elongated shape along the direction L of the predominant longitudinal extent, and two batteries 34 are located at ends of the monitoring device 3 opposite in the longitudinal direction.

The substrate 33 of the monitoring device 3 is preferably made of a flexible but inextensible material. For example, the substrate 33 is made of a polyimide or a polyester (particularly polyethylene naphthalate). Polyimide substrates are commercially manufactured and marketed, for example, by Dupont under the brand name Kapton™. Polyester substrates are commercially manufactured and marketed by Teijin under the brand name Teonex™.

According to the present invention, the interference elimination member 4 is placed between the monitoring device 3 and the inner surface 111 of the tire.

For example, Anti-Interference Element 4 is represented by 3M™ VHB™ Adhesive Tapes from 4941 Family, 4956 Family and 5952 Family or 3M™ Adhesive Tapes from RP45 Family and RP62 Family or Nitto Hyperjoint Adhesive Tapes from H8004-H8008-H8012-H9004-Family H9008-H9012.

In additional examples, the decoupling element 4 is a polyurethane foam backing from the Cirene range manufactured by Cires SpA, or an ethylene-propylene-diene monomer (EPDM) SE30 foam rubber backing from Tekspan Automotive, the backing being double sided. by layers of an acrylic adhesive (such as 3M™ 9469, 3M™ 468, 3M™ 93430, or Nitto 5925 Adhesives) applied to both surfaces of the backing or a double-sided polyurethane foam backing from the 3M™ line of “Double Coated Urethane Foam Tapes” ” (“Double Sided Polyurethane Foam Tapes”) 4004-4008-4016-4026-4032-4052-4056-4085. In further examples, the anti-interference element 4 is represented by layers of thick acrylic adhesive such as 3M™ 4411 and 4412 Tapes double-sided with a pressure-sensitive adhesive (PSA) (e.g., 3M™ 9469, 3M™ 468, 3M™ 93430 adhesives). or Nitto 5925).

The thickness of the anti-interference member, including layers of adhesive deposited on its surface, is preferably 0.4 to 2.4 mm, more preferably 0.6 to 2.2 mm, even more preferably 0.8 to 2, 0 mm and preferably from 1.0 to 1.8 mm.

The present invention will be further illustrated by means of the following examples.

Example 1 - Comparison

Test specimens were made by creating a conductive track with ECM CI-1036 flexible conductive silver-based paste on rectangular substrates having dimensions of 90×60 mm, made with different flexible materials, both tensile and non-stretchable. In particular, the following materials were used:

Substrate 1 3M™ Polyurethane Tape 8616 - 100 µm thick - made with acrylic adhesive Flexible
Tensile Substrate 2 Delstar™ EU94DS Thermoplastic Polyurethane (TPU) Film - 80 µm Thickness - No Adhesive Flexible
Tensile Substrate 3 Cross-linked polybutylene rubber film - thickness 100 µm - without adhesive flexible
Tensile Substrate 4 Kapton™ Polyimide Film - 76 µm Thickness - No Adhesive flexible
Inextensible Substrate 5 Kapton™ Polyimide Film - 127 µm Thickness - No Adhesive Flexible
Inextensible Substrate 6 Polyethylene terephthalate (PET) film - 127 microns thick - no adhesive Flexible
Inextensible Substrate 7 Polyethylene naphthalate (PEN) film Teonex Q65HA - thickness 127 microns - without adhesive Flexible
Inextensible

3M™ 93430 Acrylic Double-sided Adhesive Tape was used to adhere backings 2-7 to the inner surface of the tire (sealing layer).

The tires used were Pirelli P ZERO™ 265/35ZR22 (103W) SC tires.

The fatigue resistance test was performed on tires inflated to a controlled pressure maintained constant for the duration of the test, while the tire was subjected to a constant vertical load and rolled at a constant speed.

The test was performed on an Indoor machine with a drum having a diameter of 1.7 meters and a camber angle of 0°.

At the end of the test, the tires were removed and the adhesive grip and the strength of the conductive track were checked (compared to the values recorded before the test). The results are summarized in Table 1 below.

Table 1

Substrate Resistance (ohm) adhesive bond Before After 1 3.0 Infinite Missing disconnect 2 7.5 Infinite Missing disconnect 3 3.0 Infinite Missing disconnect 4 2.6 70 Large separation zones in the presence of adhesive on the substrate 5 2.3 6 Large separation zones in the presence of adhesive on the substrate 6 3.0 17 Large separation zones when the adhesive disappears 7 2.5 4.5 Large separation zones at the edges when the adhesive disappears or remains on the sealing layer

The test results showed that the use of substrates of flexible and tensile materials (substrates 1-3) made it possible to obtain good adhesive adhesion with acrylic adhesives (for example, type 3M 93430), but the deformations to which these materials were subjected caused the destruction of the conductive track, while while, on the contrary, the use of only flexible materials (substrates 4-7) made it possible to preserve the conductive track, but to the detriment of the adhesive bond, which deteriorated noticeably.

Example 2 - Comparison

The test of Example 1 was repeated with the same materials but using a nylon cover (Domo™ Filmon™ CSX18 cast nylon film) laminated with an adhesive (3M™ 9502) overlying the sample area.

The results are summarized in Table 2 below.

table 2

Substrate Resistance (ohm) adhesive bond Before After 1 3.0 Infinite Missing disconnect 2 7.5 Infinite Missing disconnect 3 3.0 Infinite Missing disconnect 4 2.4 13 Large separation zones in the presence of adhesive on the substrate 5 2.3 6 Large separation zones in the presence of adhesive on the substrate 6 3.1 4.5 Large separation zones when the adhesive disappears 7 2.5 2.5 Large separation zones at the edges when the adhesive disappears or remains on the sealing layer

Thus, the test results were similar to those of example 1. The tested solution did not give any improvement in terms of adhesive bonding of flexible substrates only (1-3) and in terms of the integrity of the conductive track of flexible and extensible substrates (4-7).

Example 3 - Invention

From the results of the fatigue tests described above, it appeared that the conductive paths formed on flexible and tensile substrates tended to break more and more during the test until substantially infinite resistance values were reached (i.e., until the integrity of the tracks themselves) due to the millions of entry/exit cycles of the contact patch that the tire is subjected to during the test. On the other hand, conductive paths formed on flexible and inextensible substrates instead retained optimal conductivity values, but the adhesive adhesion of the substrate to the tire liner was not guaranteed, with significant separation zones between the substrate and the adhesive at the end of the fatigue test, as well as between the adhesive and the sealing layer.

Therefore, Applicant performed an additional series of fatigue tests using flexible and inextensible substrates together with an anti-interference element placed between them and the tire. The samples used (with a size of 60×30 mm) are shown in Table 3 below.

Table 3

Sample Substrate Element to eliminate interference 1A Kapton™ polyimide film
Thickness 127 µm
Without adhesive Polyurethane Cyrene 30 2.3 mm
3M™ 93430 adhesive on both sides 2A Kapton™ polyimide film
Thickness 127 µm
Without adhesive Foam EPDM SE30 2.6 mm
3M™ 93430 adhesive on both sides 3A Kapton™ polyimide film
Thickness 127 µm
Without adhesive 3M™ 4956, 1.6 mm
3M™ 93430 adhesive on both sides 4A Kapton™ polyimide film
Thickness 127 µm
Without adhesive 3M™ VHB™ 4941, 1.1 mm, Dual Adhesive
3M™ Adhesive 93430 on the side facing the sealer 5A Kapton™ polyimide film
Thickness 127 µm
Without adhesive 3M™ VHB™ 5962, 1.6 mm, Dual Adhesive
3M™ Adhesive 93430 on the side facing the sealer 6A Kapton™ polyimide film
Thickness 127 µm
Without adhesive 3M™ RP45 1mm Dual Adhesive
3M™ Adhesive 93430 on the side facing the sealer 7A Kapton™ polyimide film
Thickness 127 µm
Without adhesive 3M™ RP62 1.6mm Dual Adhesive
3M™ Adhesive 93430 on the side facing the sealer

Table 4 below shows the results of fatigue tests carried out in the same manner as in Examples 1 and 2.

Table 4

Sample Resistance (ohm) adhesive bond Before After 1A 0.8 2.0 No disconnect 2A 0.8 1.0 No disconnect 3A 8.0 16.0 Minimum separation zone with a dimension of 3 mm on one side 4A 6.2 12.3 Minimum separation zone with a dimension of 3 mm on one side 5A 1.4 2.8 No significant disconnect 6A 7.3 12.5 No significant disconnect 7A 2.0 2.9 Minimum separation zone with a dimension of 5 mm on one side

The test results showed that the presence of the anti-interference element made it possible to obtain a good adhesive bond without adversely affecting the integrity of the conductive tracks, which maintained reasonably acceptable resistance values even after the fatigue test.

Sample 2A showed the best results with minimal increase in durability and no separation followed by samples 1A and 5A. Nevertheless, good results were obtained for the rest of the samples, which met certain requirements both in terms of adhesive adhesion to the tire and in terms of the integrity of the conductive tracks.

Example 4 - Invention

In view of the good results obtained in Example 3, the test specimens (1-7 of Table 5) were made with cigar-shaped substrates (FIG. 2) with dimensions of 110×30 mm and made with a Kapton™ polyimide film having a thickness 127 µm. Two Panasonic BR1632 batteries weighing approximately 1.8 g and measuring 16×3.2 mm were glued to the ends of each sample using a nylon cover (Domo™ Filmon™ CSX18 nylon cast film) attached by lamination with adhesive (3M™ 9502).

Despite insufficient fatigue resistance in the fatigue test, Samples 1 and 7 without the anti-interference layer were used as comparatives to test their performance in the high speed test. Sample 2 was made without traces because the ability of this anti-interference layer to maintain trace integrity has already been demonstrated. On samples 3-6, the conductive track was also formed with ECM CI-1036 flexible conductive silver-based paste. For samples 1-2 and 7, only the adhesive bonding ability was evaluated, as well as the possible presence of damage to the samples themselves or the tire.

Various types of adhesives according to Table 5 were used to adhere the samples to the inner surface of the tire (sealing layer) with or without an interference suppression layer. The total weight of the samples is shown in Table 5.

Table 5

Sample Weight
(G) adhesive De-interference layer Notes 1 5 adhesive tape
3M™ 93430 - Sample without conductive traces 2 7 adhesive tape
3M™ 93430 on both sides Tekspan EPDM SE30 2 mm Sample without conductive traces 3 8 adhesive tape
3M™ 93430 on the side facing the sealing layer 3M™ VHB 5962
1.6 mm The adhesive tape only has the function of an adhesive 4 7 3M™ VHB 5962 1.6 mm Adhesive tape also performs the function of eliminating interference 5 7 adhesive tape
3M™ 93430 on the side facing the sealing layer 3M™ VHB 4941
1.1 mm The adhesive tape only has the function of an adhesive 6 8 3M™ VHB 5962 1.6 mm Adhesive tape (with anti-interference function) was approximately 3 mm wider than the backing 7 5 adhesive tape
3M™ 93430 - Sample without conductive traces
A nylon overlay was added as in example 2

The tires used were Pirelli P ZERO™ 305/30 ZR20 (103Y) tires.

The high speed test was carried out with inflated tires loaded with a constant vertical load at increasing speeds and speeds increasing in steps.

The test was performed on an Indoor machine with a drum having a diameter of 1.7 meters and a camber angle of 0°.

At the end of the test, the tires were removed and the adhesive grip and the strength of the conductive track, if present, were checked. The results are summarized in Table 6 below.

Table 6

Sample Resistance (ohm) adhesive bond Before After 1 - - No disconnect. Almost perfect 2 - - Adhesive shrinkage: 1mm
Good adhesive bond, no separation. 3 0.07 1 Good adhesive bond, no separation.
Slight shrinkage (not measurable) 4 0.01 0.2 Minimum separation zone with a dimension of 2 mm on one side only
Slight shrinkage (not measurable) 5 5 4 3 cm offset towards the inside of the tire
Minimum decoupling zone with 3 mm dimension at the rounded end 6 2.2 1.6 Perfect adhesion, slight waviness in the center 7 - - Perfect adhesive bond, air bubble under the nylon film around the batteries

The results of the high speed test performed with the 3M™ VHB 5962 anti-interference layer confirmed the good results in the fatigue test, demonstrating good adhesion while maintaining trace integrity.

For Sample 2 with an anti-interference layer formed from ethylene-propylene-diene monomer (EPDM) porous rubber Tekspan SE30, good adhesion performance was confirmed even when tested at high speeds.

Samples 1 and 7 gave good adhesion performance at high speed, but as shown in Examples 1 and 2, they failed to guarantee adequate adhesion of the substrate in fatigue tests.

All samples also maintained tire integrity without blistering and/or other sensor-related damage.

Example 5 - Invention

Additional tests at high speeds were carried out (same as in example 4) also with copper traces obtained by chemical etching on a film of polyimide Kapton™ having a thickness of 127 microns and glued to the inner surface of the tire with VHB 5962 material having a thickness of 1 .6 mm and placed as an anti-interference element (and adhesive). Also in this case, the integrity of the conductive tracks was observed at the end of the test with a resistance value of essentially 0.5 ohms, along with maintaining proper adhesive adhesion of the substrate.

Claims (20)

1. A tire having an inner surface and at least one monitoring device glued to said inner surface, wherein the monitoring device is made on a flexible substrate, and the adhesive adhesion of the flexible substrate to said inner surface is achieved by means of an anti-interference element placed between said at least one monitoring device and said tire inner surface, wherein said interference elimination element is a double-sided adhesive tape, wherein the double-sided adhesive tape is resistant to dynamic shear stress exceeding 50 kPa. 2. The tire of claim 1, wherein said double-sided adhesive tape is a component selected from the group consisting of (i) a viscoelastic acrylic foam, (ii) a polymer foam backing, (iii) at least one layer of acrylic adhesive or (iv) combinations thereof, wherein said component (i), (ii) and (iii) has a thickness equal to or greater than 0.4 mm. 3. The tire of claim 1, wherein the double-sided adhesive tape is resistant to tire service temperatures of about -40°C to about 160°C. 4. Tire according to claim 1, wherein the double-sided adhesive tape is resistant to dynamic shear stress in excess of 150 kPa, for example in the range of 50 to 3000 kPa. 5. The tire of claim 2, wherein the polymeric foam is selected from the group consisting of ethylene-propylene-diene monomer (EPDM) porous rubber, polyurethane foam, and combinations thereof. 6. The tire of claim 2, wherein the polymeric foam backing comprises an acrylic adhesive layer coated on both surfaces of said backing. 7. Tire according to claim 2, wherein said foamed polymeric material has a density in the range of 10 to 800 kg/m ³ , preferably in the range of 20 to 700 kg/m ³ . 8. Tire according to any one of the preceding claims, wherein the anti-interference element has a thickness, taking into account the adhesive layers deposited on its surface, in the range of 0.4 to 2.4 mm, preferably in the range of 0.6 to 2, 2 mm, more preferably in the range of 0.8 to 2.0 mm. 9. Tire according to any one of the preceding claims, wherein the length and/or width of the anti-interference element is equal to or greater than, respectively, the length and/or width of the flexible substrate. 10. A tire according to any one of the preceding claims, wherein a protective layer is placed on the monitoring device to cover and protect the components of said device. 11. Tire according to claim 10, wherein the length and/or width of the protective layer is equal to or greater than the length and/or width, respectively, of the monitoring device. 12. The tire of claim 1 wherein the flexible substrate is made from an elastomeric or thermoplastic material selected from the group consisting of nylon, polyester, polyimide and polyurethane. 13. The tire of claim 12, wherein the elastomeric or thermoplastic material is resistant to tire operating temperatures that range from about -40°C to about 160°C. 14. A method for mounting a monitoring device made on a flexible substrate on a tire having an inner surface of a substantially toroidal shape, the method comprising: - selection of a section of the inner surface of the tire, on which it is desirable to install a monitoring device; - providing adhesive adhesion between the flexible substrate and the specified area of the inner surface of the tire; moreover, adhesive adhesion is provided by means of an element for eliminating interference placed between the flexible substrate and the specified area of the inner surface of the tire, wherein the element to eliminate interference is a double-sided adhesive tape, moreover, the double-sided adhesive tape is resistant to dynamic shear stress in excess of 50 kPa. 15. The method according to claim 14, wherein the anti-interference element has the characteristics of any one of claims 2 to 9.

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