Tyre comprising a monitoring device

Abstract

A Tyre (1) suitable to be mounted on a first wheel (W1) of a vehicle (C) with a determined camber angle (α), comprising: - a tread band (2), in a radially outer position, comprising a first and a second lateral axial portion (21, 22), said tread band (2) forming a footprint area (20) which, due to said camber angle (α), is asymmetrical and comprises, a first footprint length (L1) at said first lateral axial portion (21) and a second footprint length (L2) at said second lateral axial portion (22) such that said first footprint length (L1) is greater than said second footprint length (L2), said tread band (2) comprising a first circumferential groove (3) placed at said first lateral axial portion (21) and at a distance (d) from said equatorial plane (M) of said tyre (1) between 5% and 15% of a width of said tread band (2); - a monitoring device (10) constrained to a radial internal surface (L) of said tyre (1), wherein said monitoring device (10) is radially positioned at said first circumferential groove (3).

Description

[0001] DESCRIPTION

[0002] Title: TYRE COMPRISING A MONITORING DEVICE

[0003] Technical field of the invention

[0004] The present invention relates to a tyre comprising a monitoring device.

[0005] More in particular, the invention relates to a tyre of an high performance vehicle.

[0006] State of the art

[0007] Typically, a tyre has a substantially toroidal structure around its axis of rotation during operation, and it presents an equatorial plane orthogonal to the axis of rotation, said equatorial plane is typically a plane of (substantial) geometric symmetry (e.g., disregarding minor asymmetries such as tread pattern and / or sidewall markings and / or internal structure).

[0008] The term "equatorial plane" of the tyre refers to the mid-plane perpendicular to the tyre's axis of rotation.

[0009] The terms "radial" and "axial" and the expressions "radially inward / outward" and "axially inward / outward" are used with reference to the tyre's axis of rotation, while the terms "circumferential" and "circumferentially" are used with reference to the direction of the tyre's annular development, i.e., the rolling direction of the tyre, which corresponds to a direction lying on a plane coincident with or parallel to the tyre's equatorial plane.

[0010] In particular: the expression "radial direction" is used to indicate a direction substantially perpendicular to the tyre's axis of rotation.

[0011] The expression "axial direction" is used to indicate a direction substantially parallel to the tyre's axis of rotation.

[0012] The term "groove" refers to a recess made in the tread band, having at least one portion with a width between the walls that delimit it, called "groove width," of at least 1.5 mm.

[0013] The term "footprint" refers to the portion of the outer surface of the tread band that, during the rolling of the mounted tyre under load (e.g., due to mounting under a vehicle), is in contact with the rolling surface at any given moment. The footprint typically has a substantially zero curvature (or a substantially infinite radius of curvature) or, in any case, substantially conforms to the rolling surface.

[0014] An "ultra-high-speed tyre" refers to a tyre with a speed rating of at least V, corresponding to the maximum speed at which it can travel, i.e., a tyre approved to sustain a speed of 240 km / h or more.

[0015] Generally, ultra-high-speed tyres are designed to be mounted on the wheels of high-performance vehicles, preferably of the sports type. In general, tyres are mounted on their respective wheels with a non-zero camber angle, preferably negative, which results in a relatively asymmetric footprint area, in other words, a more or less "triangularized" footprint area, particularly in the case of straight-line driving.

[0016] More specifically, a "triangularized" footprint area means that it includes a footprint length, corresponding to a first lateral axial portion of the tyre's tread band, which is greater than an additional footprint length corresponding to a second lateral axial portion of the said tread band. In particular, in the case of a negative camber angle, especially in the case of straight-line driving, the greater footprint length will be on the inside (vehicle side), whereas the smaller one will be on the outside (outer side of the vehicle). In high- performance vehicles, the choice of camber angle often results in a strongly triangularized footprint area.

[0017] Patent document EP3280601B1 describes a tyre having a monitoring device installed under the respective crown, radially inside the inner crown lining, on the side of the tread intended to be positioned outside relative to the vehicle, with respect to its equatorial plane, and in such a way that the axial distance from the center of gravity of the electronic device to the equatorial plane is not more than 5% and not less than 25% of the tyre's maximum axial width LT.

[0018] Summary of the invention

[0019] However, the Applicant notes that this prior art solution is not suitable for use on a tyre with a non-zero camber angle, particularly negative, because the monitoring device would be positioned in correspondence with the portion of the footprint area having the shorter length. Specifically, for high- performance vehicles, the length of the footprint area in the portion located on the outer side can be very short.

[0020] This positioning is therefore not optimal for the functioning, for example, of algorithms based on the identification of the signal portion corresponding to the passage of the monitoring device in the footprint area: in these cases, it is important that the monitoring device is positioned in correspondence with a portion of the footprint area having a significant footprint length, thus allowing easier identification, for example, of characteristic peaks of the passage of the monitoring device in correspondence with the footprint area itself in an acceleration signal (e.g., the acceleration peak in a radial acceleration signal).

[0021] For this reason, the Applicant has recognized as optimal the positioning of the monitoring device in correspondence with the portion of the footprint area having the greater footprint length, that is, in the specific case of a negative camber angle, on the inner side (vehicle side) of the tyre.

[0022] On the other hand, due to the camber angle, in tyres configured to operate at high speeds, for example, greater than or equal to 240 km / h, there is the generation of greater stress and higher temperature precisely in correspondence with the relative inner side. All this can consequently lead to overheating of the monitoring device itself, the inner surface of the tyre, particularly the point of application of the monitoring device to the tyre, with consequent further problems that can affect the integrity of the monitoring device and / or the tyre tread.

[0023] The Applicant has found that by applying the monitoring device to the inner surface of the tyre, on the side disadvantaged by the camber angle but radially in correspondence with a circumferential groove, preferably located at a not excessive distance from the equatorial plane of the tyre, it is possible to control the temperature increase at the point of application of the monitoring device itself. Without adhering to any interpretative theory, the Applicant believes that the circumferential groove acts as a heat transfer channel, resulting in a condition where locally the point of application of the monitoring device is subjected to lower temperatures.

[0024] Preferably, this groove has a significant groove width (for example, greater than the other circumferential grooves), so as to increase the surface area available for heat dissipation.

[0025] The Applicant has found that the integrity of the device (e.g., due to the risk of battery overheating) remains at acceptable levels even at very high speeds. Furthermore, since the temperature remains locally low at the monitoring device, the integrity of the tyre also remains at acceptable levels even at very high speeds, reducing the occurrence of localized tread melting phenomena.

[0026] Additionally, the Applicant has found that the correct reception of significant parameters related to the footprint area remains particularly reliable.

[0027] According to one aspect, therefore, the invention relates to a tyre comprising a monitoring device attached to a radially inner surface of the tyre.

[0028] Advantageously, said tyre is designed to be mounted on a first wheel of a vehicle having a determined camber angle.

[0029] Preferably, an absolute value of said camber angle is between about 0.5° and about 5°.

[0030] Furthermore, preferably, the said camber angle is negative.

[0031] The tyre comprises a tread band, positioned radially outer position.

[0032] Preferably, the said tread band comprises a first and a second lateral axial portion.

[0033] Furthermore, preferably, the tread band forms a footprint area.

[0034] Preferably, due to the camber angle, the footprint area is asymmetrical and comprises a first footprint length corresponding to the first lateral axial portion and a second footprint length corresponding to the second lateral axial portion.

[0035] Preferably, the first footprint length is greater than the second footprint length. This asymmetry and, therefore, this variation in footprint lengths is due to the presence of a camber angle, as defined above.

[0036] Preferably, the tread band comprises a first circumferential groove.

[0037] Preferably, the said first groove is located in correspondence with the first lateral axial portion. Furthermore, preferably, the first groove is located at a distance from an equatorial plane of the tyre between 5% and 15% of the width of the tread band.

[0038] Advantageously, the monitoring device is positioned radially at said first circumferential groove.

[0039] Preferably, it is the center of gravity of the monitoring device that is positioned radially in correspondence with the first circumferential groove.

[0040] Advantageously, positioning the monitoring device on the side where the footprint area has the greater length and in correspondence with the first circumferential groove, as defined above, improves the integrity of the device, reducing the stress and temperature it would encounter, for example, if the monitoring device were positioned radially inside the tyre, in correspondence with the equatorial plane.

[0041] In preferred embodiments, the first lateral axial portion is configured to be positioned on the vehicle side when the tyre is mounted on the first wheel and the first wheel is mounted on the vehicle.

[0042] Advantageously, the second lateral axial portion is configured to be positioned on the opposite side of the first portion. Preferably, therefore, the second lateral axial portion is configured to be positioned on the outer side of the vehicle.

[0043] Preferably, the first circumferential groove has a width between 5 mm and 20 mm.

[0044] Preferably, between 7 mm and 17 mm.

[0045] Preferably, the tread band comprises at least one second circumferential groove.

[0046] Advantageously, the width of the first groove is greater than the width of the second groove.

[0047] With reference to the monitoring device, it preferably comprises a constraining container element capable of containing an electronic unit of the monitoring device and constraining it to the said radially inner surface of the tyre.

[0048] Preferably, the monitoring device is fixed to the said inner surface of the tyre by means of an attachment device placed at a base surface of the said constraining container element.

[0049] Preferably, such an attachment device is a pressure-sensitive adhesive layer or a structural type or a combination thereof.

[0050] Advantageously, said tyre, when mounted on the wheel, comprises an inner cavity formed by a radially outer surface of the said rim and the radially inner surface of the tyre, apart from the monitoring device.

[0051] Advantageously, the tyre, the subject of the present invention, is of the ultra-high-speed type, preferably having a speed rating of at least V.

[0052] Brief description of the drawings

[0053] - Figure 1 schematically shows a vehicle according to the present invention;

[0054] - Figures 2A, 2B, and 2C show respective front views of a portion of a tyre mounted on a vehicle at different camber angles;

[0055] - Figure 3 schematically shows a portion of a tyre equipped with a monitoring device according to an embodiment of the present invention;

[0056] - Figure 4 shows a sectional and detailed view of the view in Figure 3;

[0057] - Figure 5 shows a schematic plan view of the monitoring device in relation to the footprint area of a tyre mounted on a vehicle with a non-zero camber angle;

[0058] - Figures 6A-6F graphically show the results of a data acquisition statistic transmitted by the monitoring device based on its positioning and other conditions.

[0059] Detailed Description of Some Embodiments of the Invention

[0060] The features and advantages of the present invention will be further clarified by the following detailed description of some embodiments, presented by way of example and not limitation of the present invention, with reference to the attached figures.

[0061] Figure 1 schematically shows a vehicle C according to the present invention. The vehicle C can be an internal combustion and / or electric engine vehicle, with two or more driving wheels.

[0062] Exemplarily, the vehicle C comprises four wheels W1 (distributed on two axles), each equipped with a respective tyre 1. Preferably, the tyre 1 is of the ultra-high-speed type, preferably having a speed index of at least V.

[0063] The tyre 1 is suitable to be mounted on a first wheel W1 of a vehicle 1 with a determined camber angle o (fig. 1, 2B-2C).

[0064] Advantageously, as visible in Figures 2A-2C, 3, 4, and 5, such tyre 1 comprises a tread band 2, in a radially outer position, comprising a first lateral axial portion 21 and a second lateral axial portion 22, opposed to each other with respect to the equatorial plane M.

[0065] The aforementioned tread band 2 advantageously forms a footprint area 20 (fig. 5) which, due to said camber angle o (fig. 2B and 2C), is asymmetrical, comprising a first footprint length LI at the first lateral axial portion 21 and a second footprint length L2 at the second lateral axial portion 22. Advantageously, the first footprint length LI is greater than the second footprint length L2 (fig. 5).

[0066] The aforementioned camber angle o is preferably, in absolute value, between about 0.5° and about 5° (fig. 2B and 2C).

[0067] Preferably, the camber angle o is greater than about 0.5° in absolute value.

[0068] Preferably, the camber angle o is less than about 5° in absolute value.

[0069] Even more preferably, the camber angle o is negative. In this embodiment, the first lateral axial portion 21 is positioned on the side of the vehicle C, when said tyre 1 is mounted on said first wheel W1 and said first wheel W1 is mounted on the vehicle C (fig. 1), and the second lateral axial portion 22 is positioned on the outer side of the vehicle C.

[0070] Advantageously, the tread band 2 comprises a first circumferential groove 3 placed at said first lateral axial portion 21 (fig. 3, 4, 5).

[0071] Advantageously, the first circumferential groove 3 is preferably placed at a distance d from an equatorial plane M of said tyre 1, greater than 5% of a width of said tread band 2 (fig. 3, 4).

[0072] Preferably, the aforementioned distance d is less than 15% of a width of said tread band 2.

[0073] Advantageously, the tyre 1 exemplarily comprises a monitoring device 10 (fig. 1, 3, 4, and 5).

[0074] For example, the monitoring device 10 can be of the type described in one of the following documents in the name of the same Applicant: WO 2013 / 098711 Al, WO 2015 / 144770 Al, WO 2018 / 065846 Al, WO 2019 / 123118 Al, WO 2020 / 026281 Al, WO 2020 / 026282 Al.

[0075] Preferably, each tyre 1 of the vehicle C comprises a respective monitoring device 10. Typically, the monitoring device 10 comprises an electronic unit 101 (comprising at least one sensor of one or more operational parameters of the tyre and a transceiver device) and a power supply device 102 for the electronic unit itself, for example, one or more batteries.

[0076] In preferred embodiments, the monitoring device 10 comprises a constraining container element 11 capable of containing the electronic unit of said monitoring device 10 and constraining it to the radially inner surface L of said tyre 1 (fig. 3, 4).

[0077] Preferably, the monitoring device 10 is fixed to the inner surface L by means of a fastening device placed at a base surface of said constraining container element 11, preferably, an adhesive layer of the pressure-sensitive type or of the structural type or a combination thereof.

[0078] In preferred embodiments, the tyre 1, when mounted on said wheel Wl, comprises an inner cavity 12 formed by a radially outer surface of the rim on which the tyre 1 is mounted and the radially inner surface L of the tyre 1, except for said monitoring device 10. In other words, there are no other devices or elements fixed to the radially inner surface L of the tyre 1 besides the monitoring device 10.

[0079] Advantageously, the monitoring device 10 is radially positioned at said first circumferential groove 3 (fig. 3, 4, and 5).

[0080] In other words, as schematically shown in Fig. 4, the monitoring device has at least part of the electronic unit and / or the power supply device radially positioned at the first circumferential groove 3 (as visible from the dashed line X in fig. 4).

[0081] Preferably, the first circumferential groove 3 has a first width W3 greater than 5 mm. Even more preferably, the first circumferential groove 3 has a first width

[0082] W3 less than 20 mm.

[0083] More preferably, the first circumferential groove 3 has a first width W3 between 5 and 20 mm (fig. 4).

[0084] As exemplarily visible in figures 3, 4, and 5, preferably, the tread band 2 comprises at least a second circumferential groove 32.

[0085] Advantageously, the first width W3 of said first groove 3 is greater than a second width W32 of the second groove 32. In preferred embodiments, the first circumferential groove 3, at which the monitoring device 10 is positioned, has a width W3 greater than all the remaining circumferential grooves formed on the tread band 2.

[0086] In a series of tests, the Applicant verified the detection of lower temperatures at a groove 3 located on the inner side of the tyre 1 compared to, for example, the temperatures detected at the central portion of the tyre 1. In particular, even with strongly negative camber angles such as -2.5°.

[0087] The tests were conducted on tyres with size 335 / 30ZR.21 XL (109Y), of the asymmetric type, equipped with a monitoring device.

[0088] More specifically, the tests were carried out on a road wheel with a diameter of 2.0 m, under the following conditions:

[0089] Pressure = 2.7 bar

[0090] Vertical load = 730 kg

[0091] Camber = -2.5°

[0092] Each test involved an initial warm-up phase lasting 10 minutes to bring the tyres to a speed of 230 km / h. Subsequently, three repetitions of the following cycle were performed: 1 minute and 30 seconds at 350 km / h (maximum vehicle speed) with a vertical load of 730 kg and 3 minutes at 230 km / h (cool down), with a vertical load of 100 kg.

[0093] The result of the aforementioned tests found that the temperature detected by the monitoring devices radially positioned at an inner groove was lower compared to the positioning of the monitoring device at the central portion of the tyre 1, throughout the entire test, with a detected temperature approximately 12°C lower.

[0094] Furthermore, in this position, there were no transmission issues for the monitoring devices, unlike the tests conducted with other positions that showed signal loss of the monitoring device.

[0095] Additionally, it was found that this positioning improves the integrity of the monitoring device itself.

[0096] In figures 6A-6F, by way of example, the results of a data acquisition statistic performed at each wheel rotation by a monitoring device 10 mounted on a tyre 1 with a negative camber angle o are represented in grayscale, varying the positioning of the monitoring device 10. The higher the percentage, the more successful the synchronizations (i.e., the correct reception and decoding of the data transmitted by the monitoring device 10) and vice versa.

[0097] In particular, an acquisition was considered successful when the wheel rotation was correctly recognized.

[0098] Specifically, lighter gray represents acquisitions with a high percentage of successful synchronizations (close to 100%), while darker colors represent acquisitions with a low percentage of successful synchronizations (close to 0%).

[0099] More specifically, the letter F (Fig. 6A, 6B, 6C) indicates acquisitions made by a monitoring device 10 positioned at a front tyre 1, while the letter R. (Fig. 6D, 6E, 6F) indicates acquisitions made by a monitoring device 10 positioned at a rear tyre 1.

[0100] In the same figures:

[0101] - Reference V indicates the speed of the tyre 1, increasing in the direction of the arrow;

[0102] - Reference P indicates the pressure of the tyre 1, increasing in the direction of the arrow;

[0103] - Reference Fz indicates the vertical load on the tyre 1, increasing in the direction of the arrow; and

[0104] - Reference RGR indicates the percentage index of successful synchronizations.

[0105] Additionally:

[0106] - Reference I in figures 6A and 6D indicates that the monitoring device 10 is radially positioned at the first groove 3, on the inner side of the tyre 1 (vehicle side);

[0107] - Reference C in figures 6B and 6E indicates that the monitoring device 10 is radially positioned at a central rib, corresponding to the equatorial plane M of the tyre 1;

[0108] - Reference E in figures 6C and 6F indicates that the monitoring device 10 is radially positioned at an additional groove on the outer side of the tyre 1 (opposite side to the vehicle).

[0109] In particular, in each central column (MC), the pressure and nominal load data are represented, which ideally should be the conditions where the sensor has the best performance, close to 100% (lighter gray). Nevertheless, especially in cases where the monitoring device 10 is radially positioned at the groove on the outer side of the tyre 1 and / or at the central portion of the tyre 1, as seen from the gray shade in the respective central column MC, the sensor's performance is not entirely optimal.

[0110] As can be seen, the percentages of successful synchronizations (gray in the figures) are higher when the monitoring device 10 is radially positioned at the groove 3 on the inner side of the tyre 1, precisely where, due to the negative camber angle, the footprint length LI is greater.

Claims

Claims1. Tyre (1) suitable to be mounted on a first wheel (Wl) of a vehicle (C) with a determined camber angle (a), comprising:- a tread band (2), in a radially outer position, comprising a first lateral axial portion (21) and a second lateral axial portion (22) which are opposed to each other in relation to an equatorial plane (M) of said tyre (1) said tread band (2), when said tyre (1) is mounted and subjected to a load under said vehicle, forming a footprint area (20) which, due to said camber angle (a), is asymmetrical and comprises, a first footprint length (LI) at said first lateral axial portion (21) and a second footprint length (L2) at said second lateral axial portion (22) such that said first footprint length (LI) is greater than said second footprint length (L2), said tread band (2) comprising a first circumferential groove (3) placed at said first lateral axial portion (21) and at a distance (d) from said equatorial plane (M) of said tyre (1) between 5% and 15% of a width of said tread band (2);- a monitoring device (10) constrained to a radial internal surface (L) of said tyre (1), wherein said monitoring device (10) is radially positioned at said first circumferential groove (3).

2. Tyre (1) as in claim 1, characterized in that due to said camber angle (a), said first lateral axial portion (21) is positioned on the side of said vehicle(C), when said tyre (1) is mounted on said first wheel (Wl) and said first wheel (Wl) is mounted on said vehicle (C).

3. Tyre (1) as in claim 1, characterized in that an absolute value of said camber angle (a) is between about 0.5° and about 5°.

4. Tyre (1) as to at least one of claims 1-3, characterized in that said first circumferential groove (3) has a width between 5 and 20 mm.

5. Tyre (1) according to any one of the preceding claims, characterized in that said tread band (2) comprises at least a second circumferential groove (32).

6. Tyre (1) according to the preceding claim, characterized in that a width (W3) of said first groove (3) is greater than a width (W32) of said at least one second groove (32).

7. Tyre (1) according to at least one of the preceding claims, characterized in that said monitoring device (10) comprises a constraining container element (11) capable of containing an electronic unit of said monitoring device (10) and constraining it to said radially inner surface (L) of said tyre (1).

8. Tyre (1) as in the preceding claim, characterized in that said monitoring device (10) is fixed to said inner surface (L) by means of an attachment device placed at a base surface of said constraining container element (11), preferably, an adhesive layer of the pressure-sensitive type or of the structural type or a combination thereof.

9. Tyre (1) as at claim 1, characterized in that said wheel (Wl) comprises a rim and in that said tyre (1), when mounted on said wheel (Wl), comprises an inner cavity (12) formed by a radially outer surface of said rim and said radially inner surface (L) of said tyre (1) apart from said monitoringdevice (10).

10. Tyre (1) as at least one of the preceding claims, characterized in that said tyre (1) is of the ultra high speed type, preferably having a speed index of at least V.

Images