Improved RFID sensor device with patch-type antenna for tires

Abstract

An RFID sensor device for a tire, which is at least partially embedded / integrated or applied to the tire and includes a patch-type antenna with a multi-layer structure, the multi-layer structure including: a bottom ground plane; an intermediate dielectric substrate, which is arranged on the bottom ground plane; and one or more top conductive patches, which are arranged on the intermediate dielectric substrate and partially or completely cover the intermediate dielectric substrate, wherein the bottom ground plane and the one or more top conductive patches are short-circuited or capacitively coupled. The RFID sensor device also includes: a rigid / flexible board, which is arranged on one or more top conductive patches and / or the intermediate dielectric substrate; an RFID chip, which is mounted on the rigid / flexible board and connected / coupled to the one or more top conductive patches; a temperature sensor, which is integrated into or connected to the RFID chip; and a pressure sensor, which is mounted on the rigid / flexible board and connected to the RFID chip. The bottom ground plane: is formed by a conductive fabric / cloth / thread / fiber / yarn element / layer or by a metal weft / net / mesh; or is at least partially formed by a conductive and / or metal element / layer of the tire. The intermediate dielectric substrate is at least partially made of rubber, or is at least partially formed by a dielectric and / or rubber element / layer of the tire.

Description

Technical Field

[0001] The present invention relates to an improved radio frequency identification device (RFID) for a tire having a patch-type antenna equipped with sensors for monitoring the physical condition of the tire (such as temperature, pressure, etc.). Background Art

[0002] As is well known, tire manufacturing is a complex process in which the quality of the final product (ie, the tire) depends on the exact combination of temperature, pressure, and timing applied during manufacturing to provide the tire elastomeric compound with excellent mechanical properties.

[0003] In particular, the performance and life of a tire depends, among other things, on the environmental conditions (eg, temperature, pressure, etc.) to which the tire is subjected during manufacture and use.

[0004] Therefore, in the automotive field, especially in the tire field, there is a need to monitor the physical conditions (eg, temperature, pressure, etc.) of tires during manufacture and use.

[0005] Today, several technical solutions are known to perform this monitoring task, such as those based on Radio Frequency Identification (RFID) technology or the like.

[0006] For example, Italian patent application 102016000009727 discloses a configurable and tunable radio frequency wireless sensor device that can be advantageously integrated / incorporated into or applied to a tire to enable identification of the tire during its manufacture and use, and which is designed to also provide diagnostic data, such as temperature or pressure data, etc.

[0007] In this regard, it is worth noting that embedding RFID tags in tires during the manufacture of the tire (i.e., the elastic and highly flexible carcass) (e.g., during tire vulcanization / curing) and also during its normal operation may cause damage to the tire or its cords (e.g., may cause tire layer separation / delamination, cord / carcass ply breakage, etc.), thereby posing a safety risk.

[0008] In other words, RFID transponders used in tires should be designed to be as flexible and miniaturized as possible to match the tire properties and provide an acceptable long-range reading distance (e.g., ≥30 cm).

[0009] An improved RFID device for a tire is disclosed in the applicant's international application WO 2020 / 170057 A1, which has enhanced performance and avoids damage to the tire (or its cord), and the international application relates to an RFID device for a tire, which is designed to be applied to the inner liner of the tire before or after vulcanization / curing of the tire and includes a flexible multi-layer planar structure, which includes:

[0010] ·Substrate;

[0011] a first insulating layer covering a first portion of the substrate so as to expose a second portion thereof extending around the first portion;

[0012] An RFID chip and a first antenna, which are connected to each other and arranged on the first insulating layer;

[0013] a second antenna electromagnetically coupled to the first antenna and extending at least partially over the first insulating layer; wherein the RFID chip, the first antenna and the second antenna are located on the same plane; and

[0014] A second insulating layer covering the first insulating layer, the RFID chip, the first antenna and at least partially covering the second antenna.

[0015] In particular, the first antenna is conveniently designed to operate as a near-field coupler (for example, a two-dimensional (2D) folded structure having a ring-like or circular or rectangular or square or zigzag or spiral shape can be advantageously used), and the second antenna is conveniently designed to operate as a far-field radiating antenna.

[0016] More specifically, the second antenna is preferably a parasitic radiator, which can be conveniently formed by:

[0017] ·Meander-shaped conductive wire, or

[0018] Straight conductive wire, or

[0019] ·Assemblies of twisted conductive wires, or

[0020] ·Assemblies of twisted conductive and non-conductive wires.

[0021] According to WO 2020 / 170057 A1, a temperature sensor can advantageously be integrated into an RFID chip for measuring temperature values, wherein in addition to a meaningful identifier of the tire, the RFID chip is configured to also provide an interrogating RFID reader with the temperature value measured by the temperature sensor.

[0022] Other examples of RFID tags embedded in tires for (primarily or only) logistics / tracking / identification purposes and equipped with dipole antennas or spring antennas are disclosed in US 2017 / 0277992 A1, US 2008 / 0289736 A1 and EP 0 389 406 B1, while KR 10-0822850 B1, which relates to flexible and conductive RFID tags for tires, addresses the durability of RFID tags embedded / integrated in tires.

[0023] In addition, DE 10 2004 046193 A1 discloses a tire pressure sensor having a sensor device and an antenna device for radiating and receiving electromagnetic fields, in particular a patch antenna, more specifically a planar inverted F antenna (PIFA). The sensor device is actively designed as partly electromagnetic and is electromagnetically and operatively connected to the antenna device for radiating and receiving electromagnetic fields. The sensor device partially operates as part of an electromagnetic resonator.

[0024] In addition, US 2015 / 097662 A1 discloses a flexible board type tire pressure sensor device, which includes: a flexible printed circuit (PC) board having a first surface coupled to the inner wall of the tire of the wheel and a second surface opposite to the first surface; a sensor module installed in the second surface of the flexible PC board for sensing various conditions of the wheel; a transmission terminal group installed in the second surface of the flexible PC board and electrically connected to the sensor module for transmitting a communication program to the sensor module; and an antenna installed in the second surface of the flexible PC board and electrically connected to the sensor module for sending out a sensor signal generated by the sensor module.

[0025] Finally, EP 2 278 533 A1 discloses an RFID tag comprising: a substrate; a semiconductor package mounted on the substrate, the semiconductor package comprising a semiconductor chip packaged therein and a plurality of connection terminals thereon, the plurality of connection terminals comprising signal terminals and dummy terminals; and an antenna pattern formed on the substrate and electrically connected to the signal terminals; wherein the antenna pattern is extended to overlap with at least a portion of a bottom area of ​​the semiconductor package. Summary of the invention

[0026] In view of the foregoing, the Applicant has perceived the need for further research to develop an improved RFID sensor device for tires and has conceived the present invention.

[0027] It is therefore an object of the present invention to provide an RFID sensor device for a tire having enhanced performance and / or features with respect to the currently known solutions.

[0028] This and other objects are achieved by the present invention in that it relates to a radio frequency identification (RFID) sensor device for a tire as defined in the appended claims.

[0029] In particular, the RFID sensor device according to the present invention is designed to be at least partially embedded / integrated in or applied to a tire and comprises a patch-type antenna comprising a multi-layer structure comprising:

[0030] Bottom ground plane;

[0031] an intermediate dielectric substrate disposed on the bottom ground plane; and

[0032] • One or more top conductive patches arranged on the intermediate dielectric substrate and partially or completely covering the intermediate dielectric substrate, wherein the bottom ground plane and the one or more top conductive patches are short-circuited or capacitively coupled.

[0033] In addition, the RFID sensor device further comprises:

[0034] a rigid or flexible board arranged on said one or more top conductive patches and / or said intermediate dielectric substrate;

[0035] RFID chip mounted on the rigid / flexible board and connected / coupled to the one or more top conductive patches;

[0036] a temperature sensor, which is integrated into or connected to the RFID chip; and

[0037] • A pressure sensor mounted on the rigid / flexible board and connected to the RFID chip.

[0038] The bottom ground plane:

[0039] formed from a conductive fabric / cloth / thread / fiber / yarn element / layer, or a metallic weft / net / mesh; or

[0040] • At least partially formed by conductive and / or metallic elements / layers of the tyre.

[0041] The intermediate dielectric substrate is at least partially made of rubber or is at least partially formed by dielectric and / or rubber elements / layers of the tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] For a better understanding of the invention, preferred embodiments, intended only as non-limiting examples, will now be described with reference to the accompanying drawings (all not to scale), in which:

[0043] · Figure 1 Schematically shows a first RFID sensor device according to a first preferred embodiment of the present invention;

[0044] · Figure 2 and Figure 3 Schematically shows a second RFID sensor device according to a second preferred embodiment of the present invention;

[0045] · Figure 4 and Figure 5is a bottom view of a second RFID sensor device according to two alternative embodiments of the present invention;

[0046] · Figure 6 shows simulation results of the reading distance of the RFID sensor device according to an embodiment of the present invention relative to the operating frequency;

[0047] · Figure 7 Schematically shows an example of a third RFID sensor device according to a third preferred embodiment of the present invention being integrated into a tire;

[0048] · Figure 8 shows real-time pressure measurements of a tire rolling on a drum machine during an inflation / deflation phase, comparing pressure measurements from two RFID sensor devices according to the present invention and from a reference wired pressure gauge; and

[0049] · Fig. 9 The temperature values ​​of the tread ply of an off-road tire measured by the RFID sensor device according to the present invention are shown. DETAILED DESCRIPTION

[0050] The following discussion is presented to enable those skilled in the art to make and use the invention. Various modifications to the illustrated and described embodiments will be apparent to those skilled in the art without departing from the scope of the invention as claimed. Therefore, the present invention is not intended to be limited to the illustrated and described embodiments, but is to be accorded the broadest scope consistent with the principles and features disclosed herein and defined in the appended claims.

[0051] The present invention relates to an RFID sensor device which, in addition to providing tire identification, is also able to provide additional items of information related to the physical and / or environmental conditions to which the tire is subjected during manufacture and use, such as temperature, pressure, deformation, strain, acceleration, stress, etc. The RFID sensor device is preferably of passive type (i.e. operating without a battery). In this respect, it is worth recalling that, as is known, passive RFID devices do not require any dedicated power supply, since passive RFID devices are generally designed to extract power from radio frequency (RF) energy wirelessly transmitted by an interrogating RFID reader. However, it is worth noting that the RFID sensor device according to the present invention can also conveniently be of semi-active type (i.e. provided with its own power supply, such as a battery, etc., for powering the chip and the sensor of the RFID sensor device, while the reading operation is performed based on the RF energy emitted from the interrogating RFID reader, like a passive RFID tag).

[0052] More specifically, the present invention relates to an RFID sensor device that, in addition to providing tire identification (e.g., for logistics / tracking purposes), can also provide physical and / or environmental parameters (e.g., temperature, pressure, etc.) sensed by two or more self-organizing sensors.

[0053] The RFID sensor device according to the present invention can be advantageously used, for example, to monitor the temperature and / or inflation pressure of a tire in real time to determine the state of the tire under operating conditions (i.e., for real-time tire health monitoring) and / or to be able to replace a current inflation valve equipped with a pressure sensor of a standard tire pressure monitoring system (TPMS).

[0054] Furthermore, the RFID sensor device according to the present invention can be advantageously used for:

[0055] Quality assessment and improvement during tire production;

[0056] Optimal performance evaluation of the tire during use in a racing environment;

[0057] · Evaluation of satisfactory performance of the tire during use in an avionics environment;

[0058] Real-time monitoring of tires during their use via on-board RFID readers and / or via external RFID readers mounted at specific gates through which vehicles / trucks / buses pass.

[0059] Proper design of such RFID sensor devices has been a very challenging task due to contemporary requirements for minimization of power consumption, multi-physical parameter monitoring capabilities and operation in electromagnetically harsh environments (presence of materials / metals with high losses) and integration in tires without causing any mechanical damage or performance degradation to the tire.

[0060] Preferably, the RFID sensor device, which is conveniently designed to operate in the ultra-high frequency (UHF) RFID band (860-960 MHz), is flexible to match the mechanical properties of the tire.

[0061] More specifically, the RFID sensor device includes a radiating element (i.e., an antenna), an RFID chip, and two or more sensors for monitoring physical and / or environmental parameters, which can be conveniently integrated into the RFID chip or can be conveniently arranged outside the RFID chip and connected to the RFID chip.

[0062] The antenna (which can be conveniently connected to the RF pad of the RFID chip) is a patch-type antenna (also called a microstrip antenna, an antenna with a lower metallization or ground plane, a ground antenna or a multilayer antenna), unlike known solutions (such as those described in Italian patent applications 102016000009727 and WO2020 / 170057A1) which are typically based on a single-layer dipole-like antenna (e.g., T-matching and / or inductive coupling, for example made of conductive yarn or enameled wire).

[0063] In this regard, it is worth noting that while single-layer dipole-like antennas have the primary benefit of a thin and elongated footprint and minimal interference with the tire during integration, patch-type antennas are conversely able to withstand contact with high-loss / metallic portions of the tire (such as those present in the tire's tread) and are subject to less mechanical deformation.

[0064] In more detail, the RFID sensor device according to the present invention comprises a patch type antenna comprising a multilayer structure comprising at least three stacked layers, namely from the bottom upwards:

[0065] A bottom ground plane that:

[0066] - formed of an electrically conductive textile / cloth / thread / fiber / yarn element / layer, or of a metallic weft / net / mesh, or

[0067] - formed at least in part by conductive and / or metallic elements / layers of the tyre;

[0068] an intermediate dielectric substrate (which may conveniently comprise a plurality of layers) which is at least partly made of rubber or is formed at least partly of dielectric and / or rubber elements / layers of the tyre; and

[0069] One or more top conductive patches (which may conveniently be made of one or more conductive materials (e.g. one or more metals), which may conveniently be shaped in any manner, and which may conveniently include several slots), wherein the bottom ground plane and the top conductive patch are short-circuited or capacitively coupled.

[0070] Applicants have specifically conceived of the described multi-layer structure (with its unique antenna arrangement just described) to enable an integrated RFID sensor device within / operating in conjunction with a tire.

[0071] In particular, the bottom ground plane and the intermediate dielectric substrate (with their respective special features just described) allow providing the multilayer structure with electrical, electromagnetic and mechanical properties that enable the integration of the RFID sensor device into the tire while ensuring its proper functioning.

[0072] As previously described, the bottom ground plane can be conveniently made by utilizing some structural elements of the tire (e.g., conductive portions already present in the tire (e.g., in the tread ply)), or can be conveniently made by conductive fabric / cloth / thread / fiber / yarn elements, or metal weft yarn / net / mesh, with the spacing being appropriately sized to electromagnetically produce an equivalent continuous conductive plane at one or more operating frequencies of the RFID sensor device.

[0073] The intermediate dielectric substrate may conveniently be made of one or more flexible (e.g. felt) and / or rigid layers. In particular, the intermediate dielectric substrate may conveniently comprise (or consist of) a portion of tyre rubber. In this case, it is preferred to use a mesh / net-like bottom ground plane, which allows natural rubber to penetrate through the holes of the mesh / net-like bottom ground plane and seal with rubber used as the intermediate dielectric substrate.

[0074] The patch antenna is shielded relative to the lower metal / high loss material of the tire and is designed to focus the radiated electromagnetic field upwards and, therefore, provides improved radio frequency performance due to the reduced influence of the material (metal / high loss material) below the patch antenna and the improvement of electromagnetic radiation in the direction above the patch antenna (i.e., in the broadside direction). Therefore, the RFID sensor device according to the present invention can also be advantageously integrated in areas of the tire that include strong RFID-unfriendly materials and are more susceptible to wear and degradation (e.g., the tire tread and areas of the tire close to the bead core).

[0075] The RFID sensor device according to the present invention comprises at least a temperature sensor integrated into the RFID chip and a pressure sensor (for inflation pressure monitoring) external to and connected to the RFID chip. The RFID sensor device may conveniently also comprise one or more additional sensors (e.g., deformation sensors, strain sensors, acceleration sensors, stress sensors, additional temperature sensors, etc.) external to and connected to the RFID chip. In particular, the RFID sensor device preferably also comprises an additional temperature sensor external to and connected to the RFID chip to monitor the temperature in two points of the tire (e.g., the temperature of the tire rubber and the temperature in the tire air chamber).

[0076] The RFID sensor device can be conveniently applied / patched to the tire after the tire is vulcanized / cured (i.e., during the modification process) by means of a suitable adhesive or by implementing a similar suitable process (e.g., a surface polishing process). In addition, the RFID sensor device can be conveniently partially or completely integrated / embedded into / in the tire before the tire is vulcanized / cured.

[0077] The RFID chip and one or more external sensors (i.e., the pressure sensor and one or more additional sensors, if present) can be conveniently arranged on a rigid or flexible board to form an electronic module, which can be conveniently located:

[0078] · The center of the top conductive patch, resulting in a symmetrical and weight-balanced construction; or

[0079] • The edge of the top conductive patch, thereby improving overall flexibility and conformability.

[0080] Conveniently, the RFID chip (which, when in use, serves as a feed point for the patch antenna) may be electrically connected to the top conductive patch via a tapered microstrip line and / or direct soldering, and / or may be inductively coupled to said top conductive patch.

[0081] The RFID sensor device can be conveniently read by an antenna of an RFID reader which is integrated into the rim of a wheel or mounted on the wheel arch of a wheel, the wheel comprising a tire in which the RFID sensor device is integrated, wherein the rim / wheel arch can be conveniently modified (e.g. by introducing one or more grooves) to operate as an RFID interrogation antenna fed by a coaxial cable.

[0082] In order to better understand the present invention, Figure 1 A first RFID sensor device (indicated as a whole by 1) according to a first preferred embodiment of the present invention is schematically shown.

[0083] In particular, the first RFID sensor device 1 comprises:

[0084] Bottom ground plane 10;

[0085] An intermediate dielectric substrate 11 arranged on the bottom ground plane 10;

[0086] A first top conductive patch 12 and a second top conductive patch 13 (eg, a first top metal patch 12 and a second top metal patch 13), these top conductive patches:

[0087] - arranged on the intermediate dielectric substrate 11 so that the top elongated and middle region 11a of the intermediate dielectric substrate 11 is exposed, which serves as the radiation slot 11a of the patch type antenna, and

[0088] - short-circuited to the bottom ground plane 10 by two short-circuited metal strips 14, which are arranged at two opposite corners of the multilayer structure formed by the bottom ground plane 10, the intermediate dielectric substrate 11, and the first top conductive patch 12 and the second top conductive patch 13, and extend vertically between the bottom ground plane 10 and the first top conductive patch 12 / the second top conductive patch 13, respectively (in this regard, it is worth noting that, alternatively, the first top conductive patch 12 and the second top conductive patch 13 can be capacitively coupled to the bottom ground plane 10 without any metal strips 14);

[0089] A printed circuit board (PCB) 15, which:

[0090] - arranged partly on the first top conductive patch 12, partly on the radiation slot 11a, and partly on the second top conductive patch 13 and centered relative to said radiation slot 11a,

[0091] - electrically connected to the first top conductive patch 12 and the second top conductive patch 13 through vias 18, and

[0092] - conveniently made on a rigid substrate (e.g. based on FR4) or a flexible substrate (e.g. based on Kapton, Duroid or polyethylene terephthalate (PET));

[0093] RFID chip 16 mounted on PCB 15 and connected / coupled to both first top conductive patch 12 and second top conductive patch 13, wherein the temperature sensor ( Figure 1 ) is integrated into the RFID chip 16 (conveniently, the integrated temperature sensor has a programmable dynamic range and amplifier gain); and

[0094] A pressure sensor 17 mounted on the PCB 15 and connected to the RFID chip 16 .

[0095] Conveniently, the PCB 15 may include a plurality of pads (eg, for connecting the pressure sensor 17 and additional sensors such as deformation sensors, strain sensors, acceleration sensors, stress sensors, additional temperature sensors such as external temperature probes of the Pt1000 or negative temperature coefficient (NTC) type, etc.) Figure 1 not shown).

[0096] Figure 2 and Figure 3 A second RFID sensor device (indicated as a whole by 2) according to a second preferred embodiment of the present invention is schematically shown. In particular, Figure 2 is a perspective view of the second RFID sensor device 2, and Figure 3 It is its side view.

[0097] The second RFID sensor device 2 comprises:

[0098] A bottom ground plane 20 which may conveniently be a continuous or mesh / mesh metal layer;

[0099] an intermediate dielectric substrate 21 (conveniently, a conformal dielectric substrate) arranged on the bottom ground plane 20;

[0100] A top metal layer 22, which is disposed on the intermediate dielectric substrate 21 and serves as a single top conductive patch;

[0101] a short-circuit metal wall 23 (whose length can be conveniently dimensioned to tune the operating frequency of the second RFID sensor device 2) extending vertically on the side of the intermediate dielectric substrate 21 between the bottom ground plane 20 and the top metal layer 22, thereby short-circuiting the bottom ground plane 20 and the top metal layer 22;

[0102] three tuning notches 24 formed on the top metal layer 22 to expose three corresponding portions of the underlying intermediate dielectric substrate 21, the three tuning notches being introduced to enable miniaturization of the second RFID sensor device 2 and being conveniently sized to be tuned at its operating frequency;

[0103] A rigid or flexible board 25 (such as a PCB made on a rigid substrate (e.g., based on FR4) or a flexible substrate (e.g., based on Kapton, Duroid, or PET), which is partially arranged on the top metal layer 22 and partially arranged on the intermediate dielectric substrate 21, for housing electronic circuits;

[0104] RFID chip 26, which is mounted on the rigid / flexible board 25, where the temperature sensor ( Figure 2 and Figure 3 ) is integrated into the RFID chip 26 (conveniently, the integrated temperature sensor has a programmable dynamic range and amplifier gain);

[0105] A pressure sensor 27 mounted on the rigid / flexible board 25 and connected to the RFID chip 26 via a pad 28 of the rigid / flexible board 25; and

[0106] Additional pads 29 of the rigid / flexible board 25 for connecting additional sensors (e.g. deformation sensors, strain sensors, acceleration sensors, stress sensors, additional temperature sensors (such as external temperature probes of Pt1000 or NTC type), etc.) and / or batteries.

[0107] Figure 4 and Figure 5 is a bottom view of the second RFID sensor device 2, wherein Figure 4 In the example, the bottom ground plane 20 is formed by a continuous metal layer, while in Figure 5 In the embodiment, the bottom ground plane 20 is formed by a mesh / mesh metal layer.

[0108] Figure 6 An RFID sensor device (such as Figure 1 1) with respect to the read distance d versus the operating frequency f, wherein the intermediate dielectric substrate (sandwiched between the bottom ground plane and the top conductive patch) is connected by using a portion of tire rubber (e.g., a dielectric constant (i.e., relative permittivity) ε r In this case, even very thin constructions (i.e., intermediate dielectric substrate thickness of only 0.8 mm) can be read in the vicinity, while if the intermediate dielectric substrate is thicker (i.e., 3 mm) and the antenna is appropriately tuned, read distances greater than 50 cm can be achieved.

[0109] In the first RFID sensor device 1 and the second RFID sensor device 2, the RFID chip 16, 26 is configured to control one or more analog and / or digital external sensors (e.g., as mentioned above, the pressure sensor 17, 27 and conveniently also a deformation sensor and / or a strain sensor and / or an acceleration sensor and / or an external temperature probe, etc.). In addition, conveniently, one or more additional sensors can be directly integrated into the RFID chip 16, 26 (e.g., an acceleration sensor and / or a strain sensor with a programmable dynamic range and amplifier gain).

[0110] Preferably, the RFID chip 16, 26 is configured to perform self-tuning of its input impedance and / or the input impedance of its corresponding patch antenna to compensate for changing surrounding dielectric / electromagnetic conditions. In this way, the first RFID sensor device 1 and the second RFID sensor device 2 are able to adapt themselves to the surrounding dielectric / electromagnetic conditions (e.g., they are able to adapt themselves to the specific tire and / or the location they are applied / applied to / applied in), thereby maximizing their RFID communication performance (e.g., in terms of reading distance).

[0111] Conveniently, the RFID chip 16, 26 may also include an integrated on-chip RSSI sensor and / or an integrated matching sensor.

[0112] Additionally, the RFID chips 16, 26 may be advantageously used to:

[0113] Fully passive mode (i.e., the energy required for activation and reply is extracted entirely from the electromagnetic waves emitted by the interrogating RFID reader); or

[0114] • Battery assisted mode (ie a local battery is provided which supplies additional energy to increase the reading distance and in particular to perform periodic measurements even when the RFID reader is not interrogated (eg for data logging)).

[0115] As previously described, the RFID chips 16, 26, the pressure sensors 17, 27, and one or more additional external sensors (if present) can be conveniently arranged on a PCB made on a rigid substrate (e.g., based on FR4) or a flexible substrate (e.g., based on Kapton, Duroid or PET), where the interconnect traces can be conveniently manufactured by etching the PCB.

[0116] The first RFID sensor device 1 and the second RFID sensor device 2 can be conveniently embedded in the tire before or after the tire is vulcanized / cured. In particular, the first RFID sensor device 1 and the second RFID sensor device 2 can be conveniently embedded in the tire by being patched onto the tire inner liner (IL) after the tire is vulcanized / cured. In more detail, in order to be patched onto the tire IL after the tire vulcanization / curing process, the first RFID sensor device 1 and the second RFID sensor device 2 can be conveniently attached to the tire surface using an appropriate process (e.g., a surface polishing process) and / or an appropriate adhesive.

[0117] Conveniently, the first RFID sensor device 1 / second RFID sensor device 2 is arranged in the tire so that the pressure sensor 17 / 27 faces the inner surface of the tire and contacts the air in the tire air chamber, while the rest of the first second RFID sensor device 1 / second RFID sensor device 2 can be partially integrated into the tire itself. In this case, the pressure sensor 17 / 27 is conveniently designed or protected to withstand vulcanization / curing (for example, by using a temporary protective heat insulating cap).

[0118] Conveniently, for temperature monitoring, one can:

[0119] Monitoring the temperature inside the tire rubber by means of a temperature sensor integrated into the RFID chip 16 / 26 , wherein the first RFID sensor device 1 / the second RFID sensor device 2 is partially integrated into the tire; and / or

[0120] • Monitoring the temperature in both the inner and outer areas of the tire surface by means of an additional temperature sensor connected to the RFID chip 16 / 26.

[0121] In the two cases described previously regarding pressure and temperature monitoring, in order to ensure that the first RFID sensor device 1 / the second RFID sensor device 2 can be embedded in the tire, thereby maintaining the normal operation of the pressure sensor 17 / 27, it is convenient to:

[0122] Utilizing structural elements of the tire (e.g., conductive components inherently present within the tire itself, such as tread plies, etc.) to create the bottom ground plane 10 / 20 of the patch antenna; or

[0123] Manufacturing the ground plane 10 / 20 by means of conductive textile / cloth / thread / fiber / yarn elements, or metal weft / mesh / net, the spacing of which is suitably dimensioned to electromagnetically produce an equivalent continuous conductive plane at the operating frequency of the first RFID sensor device 1 / second RFID sensor device 2, i.e. the maximum dimension D of the holes of the metal weft / mesh / net is much smaller than the effective wavelength.

[0124] In mathematical terms, this turns out to be:

[0125] D<<λ eff / 10,

[0126] in

[0127]

[0128] in

[0129] λ0=c / f, where c represents the speed of light and f is the operating frequency of the first RFID sensor device 1 / the second RFID sensor device 2, and

[0130] ·ε eq The effective dielectric constant calculated as the volume-weighted average of the dielectric constants of the layers constituting the intermediate dielectric substrate 11 / 21 and the surrounding air is shown.

[0131] Therefore, the resulting structure is electromagnetically equivalent to a continuous conductive plane while maintaining a porous structure with holes, that is, being mechanically consistent, and allowing the natural rubber of the tire to penetrate through the holes and seal with the rubber used as the intermediate dielectric substrate 11 / 21, thereby achieving perfect integration of the first RFID sensor device 1 / second RFID sensor device 2 into the tire.

[0132] in this regard, Figure 7 An example of integrating a third RFID sensor device (indicated as a whole by 3 ) according to a third preferred embodiment of the present invention into a tire 4 is shown.

[0133] In particular, the third RFID sensor device 3 comprises:

[0134] A bottom ground plane 30 made by utilizing structural conductive elements of the tire 4 (e.g., tread plies);

[0135] an intermediate dielectric substrate 31 arranged on the bottom ground plane 30 and made by utilizing an inner liner made of rubber and a carcass ply made of fabric of the tire 4;

[0136] a top metallic layer or patch 32 arranged on the intermediate dielectric substrate 31 and exposed on the inner surface of the tire 4 so as to face the air chamber of said tire 4;

[0137] A rigid or flexible board 33, which is arranged on the top metal layer / patch 32;

[0138] RFID chip 34, which is mounted on the rigid / flexible board 33, where the temperature sensor ( Figure 7 ) is integrated into the RFID chip 34; and

[0139] A pressure sensor 35 mounted on the rigid / flexible board 33 , connected to the RFID chip 34 , and facing the air chamber of the tire 4 , so as to be able to monitor the inflation pressure of said tire 4 .

[0140] In the following, several illustrative (but non-limiting) examples of using the present invention will be described in detail.

[0141] Firstly, the invention can be used advantageously during the production and testing of tires.

[0142] In fact, the quality and mechanical / chemical properties of a tire are linked to the quality of its production process (vulcanization thermal cycle, integration of different materials) and then to the quality tests carried out. In particular, vulcanization is a very sensitive process that only takes place between 100°C and 200°C.

[0143] Production process optimization and product quality certainty therefore require temperature monitoring inside the elastomeric mixture constituting the tire, both during vulcanization and subsequent testing.

[0144] The use of traditional wired sensors (eg, thermocouples / thermal resistors) is expensive and difficult due to the need to embed cables into the rotating structure.

[0145] In contrast, the RFID sensor device according to the present invention can be advantageously used for thermal / pressure monitoring during the vulcanization phase. Furthermore, sensing data can be provided in real time for multiple sampling points in the tire during durability / speed / fatigue drum testing and throughout the life cycle.

[0146] Due to the absence of cables and batteries, the RFID sensor device according to the invention can be integrated very easily into the setup of a durability drum test and does not require any modifications to the just manufactured tire.

[0147] Furthermore, the invention allows for a reduction in the cost of instrumentation and the time required to run tests.

[0148] In another application scenario, the RFID sensor device according to the present invention can also be used in the presence of conventional wired sensors as a time- and cost-effective counter-check of the proper functionality of the pressure sensors previously used for tire parameter control during testing, thereby enabling quick identification of possible malfunctions of the sensors before the test is run.

[0149] For example, Figure 8 An example of real-time pressure monitoring during testing of a tire rolling at 60 km / h on a drum machine is shown. Figure 8 In the example shown, the tire is equipped with two RFID sensor devices (denoted Tag1 and Tag2) according to the invention patched onto the inner liner (in particular, a first RFID sensor device located near the valve, and a second RFID sensor device arranged radially at 180° relative to the valve). During rolling, the tire is inflated and suddenly deflated to simulate its rapid deflation (e.g. due to a puncture). Furthermore, a controlled stepwise increase / decrease in pressure is simulated with a good match relative to a reference sensor (the average deviation relative to the reference inflator on the valve is less than 0.03 bar). Sudden differences in the similarity between the pressure measurements obtained with the RFID sensor device according to the invention and the reference sensor allow a precise determination of a malfunction of one of the sensors.

[0150] Another advantageous application of the invention is the real-time monitoring of tires (e.g. mounted on a passenger car or off-road vehicle, or on an aircraft, or on a bus / truck) when the vehicle / aircraft / bus / truck passes through an active gate equipped with a long-range RFID reader. In particular, at the gate (e.g. when leaving and / or arriving at an airport, or in a warehouse, or at a checkpoint for tire diagnostics, etc.), the RFID reader explicitly detects the RFID sensor device embedded in the tire, reads the information items (identifier and sensed data) measured in real time, and / or downloads the time history stored in the memory of the RFID sensor device (e.g. in the case where the RFID sensor device is set to be in data logger mode). The read information items provide information about the current condition of the tires as well as their history (temperature, pressure, etc.). The data can be directly processed and sent to a cloud computing system for analysis.

[0151] By using the present invention, substantial improvements over current TPMS are achieved due to easier installation, interrogation, and data analysis.

[0152] Furthermore, by mounting an RFID reader directly onboard the vehicle / aircraft, the condition of the tires can be monitored in real time.

[0153] Additionally, a particularly advantageous application of the present invention is the monitoring of high performance racing tires. In this case, RFID readers can be conveniently mounted at the pits to monitor the physical parameters of the tires both before the start and after the end of the race. Furthermore, status updates can be provided during individual pit stops, thereby facilitating early identification of faults.

[0154] Another advantageous application of the invention is at airports. In this case, RFID readers can be conveniently installed at specific gates and / or used by ground personnel. For example, upon arrival of an aircraft, an RFID reader can read information about the temperature and pressure of the tires, thus providing valuable health information after the critical landing phase. In addition, in this way, it can also be assessed whether the aircraft has been stationary for too long and there is a loss of pressure / temperature conditions in the tires.

[0155] In addition, RFID readers can also be conveniently installed onboard an aircraft to monitor tire temperature and pressure in real time (e.g., during critical landing and braking phases).

[0156] Another advantageous application of the present invention is to monitor the temperature of the tread ply (particularly of off-road tires) under operating conditions. In fact, the RFID sensor device according to the present invention can be conveniently used to monitor the temperature of specific tire elements (such as tread ply, etc.) under operating conditions (i.e. during use).

[0157] In this case, the RFID reader may conveniently be mounted directly on the vehicle. In particular, the RFID reader may conveniently be mounted on-board the vehicle with the antenna facing the tire. Preferably, the antenna of the RFID reader may be arranged / mounted / integrated on / in the tire rim or wheel arch. For example, the wheel rim / wheel arch may conveniently comprise a slot designed to serve as an electromagnetic radiating element for reading an RFID sensor device embedded in the tire.

[0158] This application is particularly beneficial for off-road tires, which are typically subjected to strong stresses during use. In particular, the tread is the most critical area to monitor because it faces the road and is therefore subjected to the strongest fatigue.

[0159] The RFID sensor device according to the invention has an architecture particularly advantageous for its direct integration in the tread. In fact, the use of a patch-type antenna allows minimizing the adverse effects of the metal part of the tread on the electromagnetic performance. In fact, such a metal ply as well as a self-organizing metal yarn can advantageously be used to effectively manufacture the bottom ground plane of the patch-type antenna.

[0160] in this regard, Fig. 9 The temperature values ​​of the tread ply of an off-road tire measured by the RFID sensor device according to the present invention and the reference temperature data are shown. As shown in the figure, the present invention provides excellent temperature monitoring, which closely matches the reference temperature data. In particular, Fig. 9 The temperature values ​​shown in are measured by an RFID sensor device equipped with an external temperature probe, which is preferred when temperature monitoring is required at inaccessible parts of the tire, or in cases where it is almost impossible to integrate / apply the entire RFID sensor device.

[0161] Based on the foregoing, the technical advantages and innovative features of the present invention are apparent to those skilled in the art.

[0162] In summary, it is clear that numerous modifications and variations are possible to the invention, all falling within the scope of the invention as defined in the accompanying claims.

Claims

1. A radio frequency identification sensor device (1, 2, 3) for a tire, the radio frequency identification sensor device being designed to be at least partially embedded / integrated in a tire (4) or patched to a tire (4), and comprising a patch-type antenna having a multi-layer structure, the multi-layer structure comprising: Bottom ground plane (10, 20, 30); an intermediate dielectric substrate (11, 21, 31) arranged on said bottom ground plane (10, 20, 30); and one or more top conductive patches (12, 13, 22, 32) arranged on the intermediate dielectric substrate (11, 21, 31) and partially or completely covering the intermediate dielectric substrate (11, 21, 31), wherein the bottom ground plane (10, 20, 30) and the one or more top conductive patches (12, 13, 22, 32) are short-circuited or capacitively coupled, The radio frequency identification sensor device (1, 2, 3) further comprises: a rigid / flexible board (15, 25, 33) arranged on the one or more top conductive patches (12, 13, 22, 32) and / or the intermediate dielectric substrate (11, 21, 31); A radio frequency identification chip (16, 26, 34) mounted on the rigid / flexible board (15, 25, 33) and connected / coupled to the one or more top conductive patches (12, 13, 22, 32); a temperature sensor integrated into or connected to the RFID chip (16, 26, 34); and a pressure sensor (17, 27, 35) mounted on the rigid / flexible board (15, 25, 33) and connected to the RFID chip (16, 26, 34), Characterized in that the bottom ground plane (10, 20, 30): formed from an element / layer of conductive fabric / thread / fiber / yarn, or from a weft yarn / mesh of metal; or is formed at least in part from an electrically conductive and / or metallic element / layer of the tyre (4), and Therein, the intermediate dielectric substrate (11, 21, 31) is at least partially made of rubber, or is at least partially formed by dielectric and / or rubber elements / layers of the tire (4).

2. The RFID sensor device according to claim 1, further comprising one or more additional sensors, wherein the one or more additional sensors are connected to the RFID chip (16, 26, 34) via the rigid / flexible board (15, 25, 33).

3. The RFID sensor device according to claim 2, wherein: The pressure sensor (17, 27, 35) is connected to the radio frequency identification chip (16, 26, 34) via one or more first pads (28) of the rigid / flexible board (15, 25, 33), and wherein the one or more additional sensors are connected to the radio frequency identification chip (16, 26, 34) via one or more second pads (29) of the rigid / flexible board (15, 25, 33).

4. The RFID sensor device according to claim 2 or 3, wherein: The one or more additional sensors include an additional temperature sensor.

5. The RFID sensor device according to claim 2, wherein: The one or more additional sensors include one or more of the following sensors: a deformation sensor, a strain sensor, an acceleration sensor, a stress sensor, and an additional temperature sensor.

6. The RFID sensor device of claim 1, further comprising a battery connected to the RFID chip (16, 26, 34).

7. The RFID sensor device according to claim 1, wherein: The intermediate dielectric substrate (11, 21, 31) comprises one or more than one flexible and / or rigid layer.

8. The RFID sensor device according to claim 1, wherein: One or more tuning notches (24) are made in the one or more top conductive patches (12, 13, 22, 32) to expose one or more corresponding portions of the intermediate dielectric substrate (11, 21, 31) underneath.

9. The RFID sensor device according to claim 1, wherein: The rigid / flexible board (15, 25, 33) is a printed circuit board, or PCB, made on a rigid / flexible substrate.

10. The RFID sensor device according to claim 9, wherein: The rigid / flexible board (15, 25, 33) is made on a rigid substrate or a flexible substrate, wherein the rigid substrate is at least partially made of FR4, and the flexible substrate is at least partially made of Kapton, Duroid or polyethylene terephthalate.

11. The RFID sensor device according to claim 1, further comprising a short-circuit metal wall (23), the short-circuit metal wall (23) extending vertically on the side of the intermediate dielectric substrate (11, 21, 31) between the bottom ground plane (10, 20, 30) and the one or more top conductive patches (12, 13, 22, 32) to short-circuit the bottom ground plane (10, 20, 30) and the one or more top conductive patches (12, 13, 22, 32).

12. A tyre (4) comprising a radio frequency identification sensor device (1, 2, 3) according to any one of claims 1 to 11.

13. The tire according to claim 12, wherein: The RFID sensor device (1, 2, 3) is partially integrated into the tire (4) so ​​that the pressure sensor (17, 27, 35) faces the air chamber of the tire (4).

14. The tire according to claim 12 or 13, wherein: The RFID sensor device (1, 2, 3) is embedded / partially integrated / patched to the tire (4), so that the temperature sensor measures the rubber temperature of the tire (4).

15. The tire according to claim 14, wherein: The RFID sensor device (1, 2, 3) comprises an additional temperature sensor which is connected to the RFID chip (16, 26, 34) and is arranged to perform temperature measurement on the inner or outer surface of the tire (4).

16. A vehicle comprising a tyre (4) according to any one of claims 12 to 15.

17. The vehicle according to claim 16, further comprising an RFID reader connected to one or more interrogation antennas, the interrogation antennas being configured to read the temperature and pressure values ​​measured by the temperature sensor and the pressure sensor (17, 27, 35), respectively, from the RFID sensor device (1, 2, 3).

18. The vehicle according to claim 17, wherein: The RFID reader is mounted onboard the vehicle and wherein the interrogation antenna is integrated / mounted into / on the rim or wheel arch of a wheel comprising the tyre (4).

19. A vehicle according to any one of claims 16 to 18, wherein: The vehicle is a passenger car, an off-road vehicle, a racing car, an aircraft, a truck, or a bus.

20. Use of a radio frequency identification sensor device (1, 2, 3) according to any one of claims 1 to 11 for monitoring: a tyre (4) during its manufacture and testing; or Racing car tires (4); or · tires of an aircraft (4); or The tire (4) of the vehicle during use.

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