TYRE WITH MONITORING DEVICE

Abstract

The present invention relates to a tyre (11) having an inner surface (111) and provided with at least one monitoring device (3) adhering to said inner surface (111), wherein said monitoring device (3) is made on a flexible support, and wherein the adhesion of said flexible support to said inner surface (111) is achieved through a decoupling element (4) interposed between said at least one monitoring device (3) and said inner surface (111) of the tyre (11).

Claims

1. A tyre having an inner surface and at least one monitoring device adhering to said inner surface, wherein such monitoring device is made on a flexible support, and wherein the adhesion of said flexible support to said inner surface is achieved through a decoupling element interposed between said at least one monitoring device and said inner surface of the tyre.

2. Tyre according to claim 1, wherein said decoupling element comprises a double-sided adhesive tape comprising a component selected from the group consisting of (i) a viscoelastic acrylic foam, (ii) a substrate of expanded polymeric material, (iii) at least one acrylic adhesive layer, or (iv) combinations thereof, wherein said component (i), (ii) and (iii) has a thickness equal to or higher than 0.4 mm.

3. Tyre according to claim 2, wherein said double-sided adhesive tape is resistant to the operating temperatures of the tyre from about −40° C. to about 160° C.

4. Tyre according to claim 2, wherein said double-sided adhesive tape is resistant to a dynamic shear stress higher than 50 kPa, preferably higher than 150 kPa, for example ranging from 50 to 3000 kPa.

5. Tyre according to claim 2, wherein said expanded polymeric material is selected from the group consisting of expanded EPDM rubber, expanded polyurethane, and combinations thereof.

6. Tyre according to claim 2, wherein said substrate of expanded polymeric material comprises an acrylic adhesive layer coated on both surfaces of said substrate.

7. Tyre according to claim 2, wherein said expanded polymeric material has a density ranging from 10 to 800 kg/m.sup.3, preferably ranging from 20 to 700 kg/m.sup.3.

8. Tyre according to any one of the preceding claims, wherein said decoupling element has a thickness, including the adhesive layers deposited on the surfaces thereof, ranging from 0.4 to 2.4 mm, preferably ranging from 0.6 to 2.2 mm, more preferably ranging from 0.8 to 2.0 mm.

9. Tyre according to any one of the preceding claims, wherein the length and/or width of said decoupling element are equal to or greater than the length and/or width of said flexible support, respectively.

10. Tyre according to any one of the preceding claims, wherein a protective layer is disposed on said monitoring device to cover and protect the components of said device.

11. Tyre according to claim 10, wherein the length and/or width of said protective layer are equal to or greater than the length and/or width of said monitoring device, respectively.

12. Tyre according to claim 1, wherein said flexible support is made of an elastomeric or thermoplastic material selected from the group consisting of nylon, polyester, polyimide, and polyurethane.

13. Tyre according to claim 12, wherein said elastomeric or thermoplastic material is resistant to the operating temperatures of the tyre ranging from about −40° C. to about 160° C.

14. A method for installing a monitoring device made on a flexible support on a tyre having an inner surface of substantially toroidal shape, the method comprising: selecting a portion of the inner surface of the tyre wherein the monitoring device is desired to be installed; achieving the adhesion between said flexible support and said portion of the internal surface of the tyre; wherein said adhesion is achieved through a decoupling element interposed between said flexible support and said portion of the internal surface of the tyre.

15. Method according to claim 14, wherein said decoupling element has the characteristics defined according to any one of claims 2 to 9.

Description

[0077] This description is provided below with reference to the accompanying drawings, in which:

[0078] FIG. 1 shows a cross section of a tyre mounted on its support rim, with a monitoring device mounted on the inner surface of the tyre according to the invention,

[0079] FIGS. 2-4 show a schematic plan view of respective embodiments of the monitoring device used in the present invention.

[0080] FIG. 1 shows a wheel comprising a tyre 11, of the type normally known as “tubeless”, in other words without an inner tube, and a support rim 12. This tyre is inflated by means of an inflation valve 13 positioned, for example, on the channel of said rim.

[0081] The tyre 11, of which FIG. 1 is a schematic representation, has an internally hollow toroidal structure formed by a plurality of components. A metal or textile carcass structure 16 has two beads 14 and 14′, each formed along an inner circumferential edge of the carcass structure 16 for fixing the tyre 11 to the corresponding support rim 12 of the wheel. Each of the beads 14 and 14′ comprising at least one annular reinforcement core 15 and 15′, known as a bead core.

[0082] The carcass structure 16 is formed by at least one reinforcement ply which contains textile or metal cords which extend axially from one bead 14 to the other 14′ in a toroidal profile, and which has each of its ends associated with a corresponding bead core 15 and 15′. In radial tyres, the aforementioned cords are located substantially on the planes containing the rotation axis of the tyre.

[0083] An annular structure 17, known as a belt structure, normally formed by at least one layer of metal or textile cords incorporated in an elastomeric material, is positioned on the crown area of the carcass structure 16. Normally the belt structure 17 comprises two belt strips (not shown in FIG. 1) which incorporate a plurality of reinforcement cords, normally metal cords, which are parallel to each other in each strip and intersect with respect to the adjacent strip, oriented in a way such as to form a predetermined angle with respect to a circumferential direction. It is possible to optionally apply at least one further reinforcement layer (not shown in FIG. 1) to the radially outermost belt strip, said additional layer by incorporating a plurality of reinforcement cords, normally textile cords, arranged at an angle of a few degrees with respect to a circumferential direction, covered and joined together by means of an elastomeric material.

[0084] In a radially outer position with respect to the belt structure 17, a tread band 18 is applied, formed by an elastomeric material and usually having a tread pattern on the radially outermost surface for the rolling contact of the tyre with the road.

[0085] Furthermore, two sidewalls 19 and 19′ of elastomeric material, each extending radially outwards from the outer edge of the corresponding bead 14 and 14′, are positioned on the carcass structure in axially opposite lateral positions.

[0086] In tyres of the type known as tubeless, the inner surface of the tyre is normally coated with a liner 111, that is, at least one layer of air-tight elastomeric material. Finally, the tyre may comprise other known elements, for example additional reinforcement elements, rubber fillers, etc., according to the specific model of the tyre.

[0087] The system for monitoring the tyre usually comprises, in general terms, a fixed unit, preferably positioned on the vehicle in which the tyre is mounted, and a mobile unit, i.e. the monitoring device 3 containing the sensor, associated with the surface of the liner 111 of the tyre 11, as shown in FIG. 1, by means of the decoupling element 4.

[0088] As illustrated in FIGS. 2-4, the monitoring device 3 comprises at least one electronic unit 31 comprising a sensor S for measuring at least one characteristic parameter of the tyre (for example pressure, temperature, acceleration, deformation, etc.), a transmitter T for sending data to the fixed unit, and a power supply device comprising at least one accumulator 34, for supplying electrical energy to the electronic unit 31.

[0089] As an example, the sensor may be a model FXTH870911DT1 sensor marketed by NXP Semiconductors®, suitable for detecting all three physical quantities: temperature, pressure and acceleration, in particular at least the radial component and the tangential component of the acceleration.

[0090] As an example, the transmitter T may be a Bluetooth transmitter model SmartBond DA1458 marketed by Dialog Semiconductor®.

[0091] FIGS. 2-4 show two accumulators 34, but the monitoring device 3 may also comprise only one accumulator 34, or even more than two accumulators, such as for example three or four accumulators arranged symmetrically with respect to the electronic unit 31.

[0092] By way of example, the accumulators 34 may be represented by electric batteries, for example by button batteries of the CR2032HR type marketed by Maxell® (capacity 200 mAh, weight 3 g, diameter and thickness 20×3.2 mm), or BR1632A marketed by Panasonic® (capacity 120 mAh, 1.5 g, 16×3.2 mm). The typical voltage is equal to about 3V, and the operating temperature range is from −40° C. to +125° C.

[0093] The electronic unit 31 and the accumulators 34 are electrically connected through an electrical connection circuit 32 schematically shown in FIGS. 2-4.

[0094] In one embodiment, the tracks of the electrical connection circuit 32 are made with a conductive ink (e.g. DuPont® 5025 silver conductive ink) printed with a screen printing technique directly on the flexible substrate 33.

[0095] The electronic unit 31 and the accumulator or accumulators 34 are arranged and glued on the flexible support 33, for example by means of conductive adhesive (e.g. Henkel 3104 WXL) and structural adhesive (e.g. Henkel A312).

[0096] In the embodiment shown in FIGS. 2 and 3, two accumulators 34 are arranged on opposite sides of the electronic unit 31.

[0097] For example, in the embodiment according to FIG. 2 the dimensions along the longitudinal direction and along the orthogonal dimension (in the plane of FIG. 2) may be equal to 110×30 mm or 80×25 mm. The distance D between the two accumulators 34 is equal to about 70 mm in the case of dimensions 110×30 mm, while for dimensions equal to 80λ25 mm, the distance D is equal to about 50 mm.

[0098] In the embodiment shown in FIG. 4, the monitoring device 3 has a plan (e.g. defined by the plan of the flexible support 33) with an elongated shape along a prevailing longitudinal development direction L, and two accumulators 34 are arranged at the longitudinally opposite ends of the monitoring device 3.

[0099] Preferably, the support 33 of the monitoring device 3 is made of a flexible but non-extensible material. For example, the support 33 is made of polyimide or polyester (in particular polyethylene naphthalate). Polyimide supports are commercially available, for example, from Dupont under the Kapton™ brand. Polyester supports are commercially available from Teijin under the Teonex™ brand.

[0100] According to the present invention, a decoupling element 4 is interposed between the monitoring device 3 and the inner surface of the tyre 111.

[0101] For example, the decoupling element 4 is represented by adhesive tapes 3M™ VHB™ of the 4941 family, the 4956 family and the 5952 family, or by the 3M™ adhesive tapes of the RP45 family and the RP62 family, or by the Nitto Hyperjoint adhesive tapes of the H8004-H8008-H8012-H9004-H9008-H9012 family.

[0102] In further examples, the decoupling element 4 is represented by a polyurethane foam substrate of the Cirene line produced by the company Cires SpA or by an EPDM foam rubber substrate SE30 produced by the Tekspan Automotive company, made double-sided by means of acrylic adhesive layers. (for example 3M™ 9469, 3M™ 468, 3M™ 93430 or Nitto 5925 adhesives) spread on both substrate surfaces, or a double-sided polyurethane foam substrate from the 3M™ line of adhesive tapes from the “Double Coated Urethane Foam Tapes” family 4004-4008-4016-4026-4032-4052-4056-4085. In further examples, the decoupling element 4 is represented by layers of thick acrylic adhesive such as the 3M™ 4411 and 4412 tapes, made double-sided by a PSA adhesive (for example, the 3M™ 9469, 3M™ 468, 3M™ 93430 or Nitto 5925 adhesives).

[0103] The thickness of the decoupling element, including the adhesive layers deposited on its surfaces, is preferably between 0.4 and 2.4 mm, more preferably between 0.6 and 2.2 mm, even more preferably between 0.8 and 2.0 mm, and advantageously between 1.0 and 1.8 mm.

[0104] The present invention will now be further illustrated by the following examples.

Example 1—Comparison

[0105] Test samples were made by creating a conductive track with ECM CI-1036 silver-based flexible conductive ink on rectangular substrates having dimensions 90×60 mm made with different flexible materials, both extensible and non-extensible. In particular, the following materials were used:

TABLE-US-00001 Substrate 1 3M ™ 8616 polyurethane tape-100 μm Flexible thickness-provided with acrylic adhesive Extensible Substrate 2 Delstar ™ EU94DS thermoplastic Flexible polyurethane film (TPU)-80 μm thickness- Extensible without adhesive Substrate 3 Cross-linked polybutylene rubber film-100 Flexible μm thickness-without adhesive Extensible Substrate 4 Kapton ™ polyimide film-76 μm thickness- Flexible without adhesive Non-extensible Substrate 5 Kapton ™ polyimide film-127 μm Flexible thickness-without adhesive Non-extensible Substrate 6 PET film-127 μm thickness-without Flexible adhesive Non-extensible Substrate 7 Teonex Q65HA PEN film-127 μm Flexible thickness-without adhesive Non-extensible

[0106] To adhere substrates 2-7 to the inner surface of the tyre (liner), the 3M™ 93430 acrylic double-sided adhesive tape was used.

[0107] The tyres used were Pirelli P ZERO™ 265/35ZR22 (103W) SC.

[0108] A fatigue resistance test was carried out on tyres inflated to controlled pressure kept constant for the duration of the test, subjected to constant vertical load and subjected to rolling at constant speed.

[0109] The test was carried out on an Indoor machine with a 1.7 meter diameter drum with a camber angle equal to 0°.

[0110] At the end of the test, the tyres were removed and the adhesion and strength of the conductive track was checked (compared to the values recorded before the test). The results are summarised in the following Table 1.

TABLE-US-00002 TABLE 1 Resistance (Ω) Substrate Before After Adhesion 1 3.0 Infinite No detachment 2 7.5 Infinite No detachment 3 3.0 Infinite No detachment 4 2.6 70 Large detachments with adhesive on the substrate 5 2.3 6 Large detachments with adhesive on the substrate 6 3.0 17 Large detachments with disappearance of the adhesive 7 2.5 4.5 Large detachments on the edges with disappearance of the adhesive or residues on the liner

[0111] The test results showed that the use of substrates with flexible and extensible materials (substrates 1-3) allowed obtaining a good adhesion with acrylic adhesives (for example of the type 3M 93430), but the deformations suffered by these materials caused breakage of the conductive track, while on the contrary the use of only flexible materials (substrates 4-7) allowed preserving the conductive track, but to the expense of the adhesion which worsened visibly.

Example 2—Comparison

[0112] The test of example 1 was repeated, with the same materials but using a covering layer of nylon (Nylon cast film Domo™ Filmon™ CSX18) laminated with adhesive (3M™ 9502) protruding from the sample area.

[0113] The results are summarised in the following Table 2.

TABLE-US-00003 TABLE 2 Resistance (Ω) Substrate Before After Adhesion 1 3.0 Infinite No detachment 2 5.0 Infinite No detachment 3 3.0 Infinite No detachment 4 2.4 13 Large detachments with adhesive on the substrate 5 2.3 6 Large detachments with adhesive on the substrate 6 3.1 4.5 Large detachments with disappearance of the adhesive 7 2.5 2.5 Large detachments on the edges with disappearance of the adhesive or residues on the liner

[0114] The test results were therefore similar to those of example 1. The tested solution gave no improvement on the adhesion of the only flexible substrates (1-3) and on the integrity of the conductive track of the flexible and extensible substrates (4-7).

Example 3—Invention

[0115] From the fatigue resistance tests described above it emerged that the conductive tracks reported on flexible and extensible substrates tended to degrade progressively during the test, until reaching substantially infinite resistance values (i.e. until the interruption of the electrical continuity of the tracks themselves), due to the millions of footprint entry/exit cycles to which the tyre is subjected during the test. On the other hand, the conductive tracks reported on flexible and non-extensible substrates instead preserved optimal conductivity values, but the adhesion of the substrate to the tyre liner was not guaranteed, with significant detachments between substrate and adhesive, as well as between adhesive and liner, at the end of the fatigue test.

[0116] The Applicant has therefore carried out a further series of fatigue resistance tests using flexible and non-extensible substrates, with a decoupling element interposed. The samples used (60×30 mm in size) are shown in Table 3 below.

TABLE-US-00004 TABLE 3 Sample Substrate Decoupling element 1A Kapton ™ polyimide film PU Cyrene 30 2.3 mm Thickness 127 μm 3M ™ 93430 adhesive on Without adhesive both sides 2A Kapton ™ polyimide film EPDM foam SE30 2.6 mm Thickness 127 μm 3M ™ 93430 adhesive on Without adhesive both sides 3A Kapton ™ polyimide film 3M ™ 4956, 1.6 mm Thickness 127 μm 3M ™ 93430 adhesive on Without adhesive both sides 4A Kapton ™ polyimide film 3M ™ VHB ™ 4941, 1.1 mm Thickness 127 μm with two adhesive Without adhesive surfaces. 3M ™ 93430 adhesive on the inner liner side. 5A Kapton ™ polyimide film 3M ™ VHB ™ 5962, 1.6 mm Thickness 127 μm with two adhesive Without adhesive surfaces. 3M ™ 93430 adhesive on the inner liner side. 6A Kapton ™ polyimide film 3M ™ RP45, l mm, with two Thickness 127 μm adhesive surfaces. Without adhesive 3M ™ 93430 adhesive on the inner liner side. 7A Kapton ™ polyimide film 3M ™ RP62, 1.6 mm with Thickness 127 μm two adhesive surfaces. Without adhesive 3M ™ 93430 adhesive on the inner liner side

[0117] The following table 4 shows the results of the fatigue resistance tests carried out in the same way as in examples 1 and 2.

TABLE-US-00005 TABLE 4 Resistance (Ω) Sample Before After Adhesion 1A 0.8 2.0 No detachment 2A 0.8 1.0 No detachment 3A 8.0 16.0 Minimum detachment of 3 mm on one side 4A 6.2 12.3 Minimum detachment of 3 mm on one side 5A 1.4 2.8 No substantial detachment 6A 7.3 12.5 No substantial detachment 7A 2.0 2.9 Minimum detachment of 5 mm on one side

[0118] The test results showed that the presence of the decoupling element allowed obtaining good adhesion without negatively affecting the integrity of the conductive tracks, which maintained sufficiently adequate resistance values even after the fatigue resistance test.

[0119] Sample 2A showed the best results with minimal increase in endurance and no detachment, followed by samples 1A and 5A. The other samples, however, obtained good results, which met the specific requirements both in terms of adhesion to the tyre and integrity of the conductive tracks.

Example 4—Invention

[0120] In view of the good results obtained with example 3, test samples (1-7 of table 5) were made with substrates having a cigar shape (FIG. 2) having dimensions 110×30 mm made with Kapton™ polyimide film having thickness of 127 μm. Two Panasonic BR1632 batteries weighing approximately 1.8 g and sized 16×3.2 mm were glued to the ends of each sample using a covering layer of nylon (Nylon cast film Domo™ Filmon™ CSX18) laminated with adhesive (3M™ 9502).

[0121] Despite the poor resistance to the fatigue test, samples 1 and 7 without a decoupling layer were used as a comparison to verify their performance in the high speed test. Sample 2 was made without conductive tracks as the ability of this decoupling layer to maintain the integrity of the conductive tracks had already been demonstrated. On samples 3-6 a conductive track was also made with silver-based flexible conductive ink ECM CI-1036. On samples 1-2 and 7 only the adhesion capacity was assessed, as well as the possible presence of damage to the samples themselves or to the tyre.

[0122] To adhere the samples to the inner surface of the tyre (liner), different types of adhesive were used as per table 5 with or without a decoupling layer. The total weight of the samples is shown in table 5.

TABLE-US-00006 TABLE 5 Weight Decoupling Sample (g) Adhesive layer Notes 1 5 Adhesive tape — Sample without 3M ™ 93430 conductive strips 2 7 Adhesive tape Tekspan Sample without 3M ™ 93430 on EPDM conductive strips both sides SE30 2 mm 3 8 Adhesive tape 3M ™ VHB The adhesive tape 3M ™ 93430 on 5962 has only an adhesive the inner liner side 1.6 mm function 4 7 3M ™ VHB 5962 1.6 mm The adhesive tape also performs a decoupling function 5 7 Adhesive tape 3M ™ The adhesive tape 3M ™ 93430 on VHB 4941 has only an adhesive he inner liner side 1.1 mm function 6 8 3M ™ VHB 5962 1.6 mm The adhesive tape (with decoupling function) was about 3 mm wider than the substrate 7 5 Adhesive tape — Sample without 3M ™ 93430 conductive strips A covering layer of nylon was added as for example 2

[0123] The tyres used were Pirelli P ZERO™ 305/30 ZR20 (103Y).

[0124] A high speed test was carried out on inflated tyres stressed with constant vertical load, with increasing speeds and periodically increased in steps.

[0125] The test was carried out on an Indoor machine with a 1.7 meter diameter drum with a camber angle equal to 0°.

[0126] At the end of the test, the tyres were removed and the adhesion and strength of the conductive track, where present, was checked. The results are summarised in the following Table 6.

TABLE-US-00007 TABLE 6 Sample Resistance (Ω) Before After Adhesion 1 — — No detachment. Almost perfect 2 — — Adhesive shrinkage: 1 mm Good adhesion, no detachment. 3 0.07 1 Good adhesion, no detachment. Slight shrinkage (not measurable) 4 0.01 0.2 Minimum detachment of 2 mm on one side only Slight shrinkage (not measurable) 5 5 4 3 mm displacement towards the inner side of the tyre Minimum detachment of 3 mm on the rounded end 6 2.2 1.6 Perfect adhesion, slight ripple in the centre 7 — — Perfect adhesion, air bubble under the nylon film around the batteries

[0127] The results of the high speed test carried out with the 3M™ VHB 5962 decoupling layer confirmed the good results of the fatigue resistance test, demonstrating good adhesion and at the same time maintaining the integrity of the conductive track.

[0128] Sample 2, with the decoupling layer made of Tekspan SE30 foamed EPDM rubber confirmed the good adhesion features even in the high speed test. Samples 1 and 7 gave good adhesion features at high speed, but as shown in examples 1 and 2 they fail to guarantee a correct adhesion of the substrate in the fatigue resistance tests.

[0129] All the samples also preserved the integrity of the tyre, without the formation of blisters and/or other damage, in conjunction with the sensor.

Example 5—Invention

[0130] Further high-speed tests were conducted (in the same way as in example 4) also with conductive copper tracks obtained by chemical etching on a 127 μm thick Kapton™ polyimide film, adhered to the inner surface of the tyre with a VHB 5962 having 1.6 mm thickness interposed as a decoupling element (and adhesive). Also in this case, at the end of the tests, the integrity of the conductive tracks was observed, with a resistance value substantially equal to 0.5Ω, together with maintaining the correct adhesion of the substrate.