GB2565209A

GB2565209A - Tread measuring system

Info

Publication number: GB2565209A
Application number: GB1809402.9A
Authority: GB
Inventors: Anzil Riccardo
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-05-25
Filing date: 2018-06-07
Publication date: 2019-02-06
Also published as: GB201709050D0; GB201708365D0; GB201809402D0

Abstract

A system comprising at least one sensing system embedded inside a vehicle tyre with means to connect or interface with external electronics capable of calculating or interpolating the amount of wear on the tyre tread. The sensing parts capacitance, resistance, impedance, inductance and/or continuity may be affected by the depth of tread. The sensing part may comprise a foil or wire embedded in the tyre, protruding into at least one tread block such that electrical continuity is interrupted when tyre wear reaches a certain threshold. The sensing part may comprise two conductive plates separated by an insulating layer to form a capacitor. The sensing part may comprise at least one coil, the inductance of which can be measured. The sensing part may comprise a material or compound with magnetic properties.

Description

TREAD SENSING

FIELD OF INVENTION

This invention relates to devices, systems and methods to monitor tire tread level and/or whether it reaches some pre-determined wear level.

SUMMARY

For a tire to perform within certain levels of performance and safety its tread channels have to be deeper than a certain value. If not, when used on wet terrain the tire can aquaplane resulting increasing risks of loss of control of the vehicle. The in order to know whether a tire tread is within its safe limits currently it has to be looked at and measured.

GENERAL DESCRIPTION

According to the present invention there is provided vehicle tire tread level sensing devices and systems as well as systems and methods to connect and interface them to electronic systems/devices which are not embedded in the tire itself. The present invention intends to cover such devices and systems as well as vehicle tires incorporating them.

According to the present invention there is provided a sensor embedded into a tire preferable but not necessarily above all metal layers/plies/belts and in such position and orientation that electrical continuity and/or capacitance and/or inductance and/or resistance of any of its parts are affected/changed by variation of tread depth (i.e. tire wear) in such a way that electronics connected to it can measure such affections/changes can be correlated to the tread level so to calculate or estimated its level/status and/or it being worn past a certain threshold.

Multiple sensors can be connected in series and/or in parallel to each other as to create a sensor network which covers/monitors different areas of the tire and tire's tread.

The electronics which usually drives, controls and reads the sensor state or characteristics is preferably placed external to the tire and preferable but not necessarily placed on the wheel rim. Such electronics can be a dedicated device enclosed in a separate enclosure or be embedded into the tire pressure monitoring system unit which most cars nowadays already have in each wheel.

The connectivity of the sensor to the electronics can be achieved through resistive means such as electrically conductive wires, conductive compounds (including conductive polymers and rubbers) or through capacitive coupling. Capacitive coupling includes a configuration whereby each of the capacitor-behaving devices is formed by two plates-like surfaces ideally as parallel to each other as possible and one or more dielectric materials between them. In such configuration one of the platelike surface is embedded into the tire in the area between the tire's bead wires and the outer rubber surface just below it (i.e. in the direction towards the wheel rim). The second plate is then placed on a substrate (also referred to in this application as flexi-strip) which isolates it from the wheel. For ease of assembly, such substrate can be locked in place preferably but not necessarily by adhesive means such as adhesive tape. The tire is then installed onto the wheel ensuring the two plates are aligned. Once the tire is installed on the wheel, the rubbed compressed between the tire bead wires and the substrate forms the dielectric between the two plates hence forming a capacitor. Such capacitive coupling becomes part of the circuit the sensor is connected to.

This invention intends to cover the sensor types mentioned, one or more such sensors embedded in it, all connecting means just mentioned and the additional ones mentioned further below In this application, the fact that the electronics interfaced to the sensor/s is enclosed into and/or part of the TPMS (tire pressure monitoring sensor/system) and a wheel with pre-installed/included electronics and/or with pre-installed/including connectivity means such as the substrate described above and those described further below in this application (also referred to as flexi-strip).

According to the present invention there is provided a vehicle tire with one or more sensing device/apparatus/system embedded entirely or partially inside the tire itself ideally, but not necessarily, above the radially outward topmost ply and in such a way that at least part of said apparatus/device/system protrudes into at least one tread block so that their measurable/detectable characteristics including but not limited to resistance, capacitance, electrical continuity and any combination of the above can change or can be affected by tire wear and where/whereby such changes can be sensed and/or measured by an electronic device ideally but not necessarily comprising a microcontroller/microprocessor unit embedded in such device/apparatus/system or somewhere into the tire or somewhere into/onto the wheel including the wheel radially outwards outer surface in the tire-wheel assembly pressurised chamber that such tire is mounted on and which can correlate them to tire wear level and/or to tire tread wear having reached a specific level and which can send such information to another system ideally but not necessarily wirelessly.

According to the present invention both the devices/apparatuses and systems described as well as a tire, wheel and tire and wheel assembly containing, using or having such devices/apparatuses incorporated into them and/or mounted into/onto them are covered.

According to the present invention there are provided apparatuses, devices, systems and methods mounted entirely or partially inside the rubber compound of a tire ideally, but not necessarily, between the tires layers which monitor said tire tread level/status/wear and/or whether it reaches some pre-determined wear level without need to inspect the tire visually and without the need to measure the thread depth by manually placing specific measuring instruments (such as a tire tread depth gauge) against the tire tread.

According to the present invention there is provided a tread-depth sensing device/apparatus whereby an electric conductor is placed/embedded preferably during tire manufacturing inside a tire's tread block and with at least a part of it above bottom tread grooving surface so that when tire tread wear level reaches it, it is broken and by breaking it also breaks the electrical continuity of one or more circuits of which it is part and/or to which it is connected and where such circuit has the ability to calculate, derive or in any way work out the status of the tire tread and can also relay/communicate the acquired and/or derived information about tread wear/status to a user directly and/or to other systems (such as by way of example a car wireless network). Preferably but not necessarily, such circuit has at least a microcontroller, means to generate and/or store energy, means to interface to such apparatus/device and means to connect to remote apparatuses, devices or system in a wired and/or wireless way (including to a wireless system in a vehicle).

According to the present invention there is provided a tread-depth sensing apparatus/device whereby an electrically resistive conductor is placed/embedded preferably during tire manufacturing inside a tire's tread block with at least a part of it above bottom tread grooving surface so that when tire tread wear level reaches a certain level it begins wearing together with the tire tread (ideally at the same rate) and so that as such wear increases the electrical characteristics such as resistance and/or capacitance change and where such changes can be monitored/detected/measured by one or more electronic circuits of which it is part and/or to which it is connected and where such circuit has the ability to calculate, derive or in any way work out the status of the tire tread and can also relay/communicate the acquired and/or derived information about tread wear/status to the user directly or to other systems (such as by way of example a car wireless network). Preferably but not necessarily, such circuit has at least a microcontroller, means to generate and/or store energy, means to interface to such apparatus/device and means to connect to remote apparatuses, devices or system in a wired and/or wireless way (including to a wireless system in a vehicle).

According to the present invention there is provided a tire's tread-depth sensing system where a number of the devices described above are inserted inside a single tire and connected to each other and/or to an electronic processing unit placed within the sensor or somewhere on the tire (ideally inside the pressurised chamber) or somewhere on the wheel the tire is mounted on.

According to the present invention this system can be implemented/applied to any tire for any vehicle.

According to the present invention there are provided apparatuses, devices and systems which embed conductors inside a tire. According to the present invention there are provided apparatuses, devices and systems which embed conductors inside a tire and provide means to electrically connect to such conductors. According to the present invention there are provided apparatuses, devices and systems which embed conductors inside a tire and provide means to electrically connect to such conductors by exposing at least part of such conductors outside the tire by having a wire, thread, foil or other ideally, but not necessarily, flexible part of it exit the tire assembly through one or more layers of the tire compounds/structures, preferably through the outer rubber compounds.

DETAILED DESRIPTION

For the current invention to be more readily understood embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 2 is an enlarged view of detail 15 in figure 1,

Figure 3 is an enlarged view of detail 12 in figure 1,

Figure 4 shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 5 is an enlarged view of detail 19 in figure 4,

Figure 6 shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 7 is an enlarged view of detail 23 in figure 6,

Figure 8 is an enlarged view of detail T1 in figure 6,

Figure 9 shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 10 is an enlarged view of detail 38 in figure 9,

Figure 11 is an enlarged view of detail 40 in figure 9,

Figure 12 shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 13 is an enlarged view of detail 39 in figure 9,

Figure 14 is an enlarged view of detail 42 in figure 12

Figure 15 shows a perspective partial cross-sectional exploded view of a tire and wheel assembly and embodiment of a sensor apparatus in accordance with the present invention,

Figure 16 is an enlarged view of detail 63 in figure 15,

Figure 17 shows a cross-sectional exploded view of a tire and wheel assembly and embodiment of a sensor apparatus in accordance with the present invention,

Figure 18 is an enlarged view of detail 45 in figure 17,

Figure 19 is a perspective partial cross-sectional view of a wheel and embodiment of a connecting apparatus in accordance with the present invention,

Figure 20 is a perspective partial cross-sectional view of a wheel and embodiment of a connecting apparatus in accordance with the present invention,

Figure 21 is a perspective partial cross-sectional view of a wheel and embodiment of a connecting apparatus in accordance with the present invention,

Figure 22 is an enlarged view of detail 78 in figure 21,

Figure 23 is a perspective partial cross-sectional view of a wheel and embodiment of a connecting apparatus in accordance with the present invention,

Figure 24 is an enlarged view of detail 79 in figure 23,

Figure 25 is a perspective partial cross-sectional view of a wheel and embodiment of a connecting apparatus in accordance with the present invention,

Figure 26 is an enlarged view of detail 80 in figure 25,

Figure ΤΊ shows a perspective partial cross-sectional view of a tire and embodiment of a sensor apparatus in accordance with the present invention,

Figure 28 is a perspective partial cross-sectional view of a tire and wheel assembly and embodiment of a sensor apparatus in accordance with the present invention,

Figure 29 is an enlarged view of detail 87 in figure 28,

Figure 30 shows a cross-sectional view of a tire and wheel assembly and embodiment of a sensor apparatus in accordance with the present invention,

Figure 31 is an enlarged view of detail 90 in figure 30,

Figure 32 is an enlarged view of detail 89 in figure 30,

Figure 33 is a perspective partial cross-sectional view of a wheel assembly and embodiment of a connecting apparatus in accordance with the present invention,

Figure 34 is an enlarged view of detail 132 in figure 33,

Figure 35 is a perspective partial cross-sectional view of a wheel assembly and embodiment of a connecting apparatus in accordance with the present invention,

Figure 36 is an enlarged view of detail 94 in figure 35,

Figure 37 is a perspective partial cross-sectional view of a tire and wheel assembly and embodiment of a sensor apparatus in accordance with the present invention,

Figure 38 is an enlarged view of detail 67 in figure 37,

Figure 39 is an enlarged view of detail 131 in figure 37,

Figure 40 is a perspective view of a flexi-strip connecting apparatus in accordance with the present invention,

Figure 41 is an enlarged view of detail 100 in figure 40,

Figure 42 is a perspective view of a flexi-strip connecting apparatus in accordance with the present invention,

Figure 43 is an enlarged view of detail 101 in figure 42,

Figure 44 is a perspective view of a flexi-strip connecting apparatus in accordance with the present invention,

Figure 45 is an enlarged view of detail 102 in figure 44,

Figure 46 is a perspective view of a flexi-strip connecting apparatus in accordance with the present invention,

Figure 47 is an enlarged view of detail 190 in figure 46,

Figure 48 is a perspective view of an embodiment of a sensor apparatus in accordance with the present invention

Figure 49 is a perspective view of an embodiment of a sensor apparatus in accordance with the present invention

Figure 50 is a perspective view of an embodiment of a connective apparatus in accordance with the present invention

Figure 51 is a perspective view of an embodiment of a connective apparatus in accordance with the present invention

Figure 52 is a perspective view of an embodiment of a sensor apparatus in accordance with the present invention

Figure 53 is a perspective view of an embodiment of a sensor apparatus in accordance with the present invention

Figure 54 is a block diagram of one apparatus in accordance with the present invention

Figure 55 is a block diagram of one apparatus in accordance with the present invention

Figure 56 is a block diagram of one apparatus in accordance with the present invention

Figure 57 is a block diagram of one apparatus in accordance with the present invention

Figure 58 is a block diagram of a subsystem 222 depicted in figure 57

Figure 59 is a perspective view of an embodiment of a capacitive sensor apparatus embedded in the tyre

Figure 60 is a perspective view of an embodiment of a capacitive sensor apparatus embedded in the tyre

Figure 61 is a top view of an embodiment of a projected capacitance capacitive sensor apparatus with capacitive plates above each other

Figure 62 is a perspective view of an embodiment of a capacitive sensor apparatus shown in Fig 61

Figure 63 is a perspective exploded view of an embodiment of a capacitive sensor apparatus shown in Fig 61 and 62

Figure 64 and 65 are a cross sectional view 305 of the sensing area of the capacitive sensor shown in Fig 61 to 63

Figure 66 is a top view of an embodiment of a projected capacitance capacitive sensor apparatus with capacitive plates next to each other

Figure 67 is same as Fig 66 but also showing the embedded capacitive plates their connected traces and pads (by the dotted lines)

Figure 68 is a perspective exploded view of an embodiment of a capacitive sensor apparatus as shown in Fig 66 and 67

Figure 69 and 70 are a cross sectional view 306 of the sensing area of the capacitive sensor shown in Fig 66 to 68

Figure 71 is a top view of an embodiment of an inductive sensor apparatus containing a coil

Figure 72 is same as Fig 71 but also showing the embedded coil and its connected traces and pads by the dotted lines

Figure 73 is a perspective exploded view of an embodiment of an inductive sensor apparatus as shown in Fig 71 and 72

Figure 74 and 75 are a cross sectional view 307 of the sensing area of the inductive sensor shown in Fig 71 to 73

Fig 55 is a general block diagram representing a simple configuration of the systems and devices covered by this patent application. The area enclosed by 237 represents a vehicle tire and what is attached/embedded/molded in it. The area enclosed by 238 represents a vehicle wheel onto which the tire is installed. 205 represents sensor devices/systems subject of this patent application which directly or indirectly reflect, detect or measure tread wear level. Different types of 205 are described in this document and are all intended to be covered by this patent application. 160 and 167 are means (preferable but not necessarily conductive wires or traces) to connect 205 to contacts, connectors or any other means 161 and 166 which in turn connect/interface to external systems/devices. 206 represent any electronics, device or system which can (preferably electrically) interface with 205 to interact with it and/or control it and/or read/detect its status. 206 ideally, but not necessarily, also relays such information and/or any other derived information (such as interpolated correlations of sensor reading to tire tread level) to any other external system such as by way of example a vehicle sensors monitoring system or vehicle tire monitoring system, this is preferable but not necessarily done by wireless means/connectivity including but not limited to RF. 238 is connected/interfaced to 237 through means such as 161, 162, 165 and 166 which represent devices/means/systems to allow current and/or information to flow between the two sub-systems represented by 238 and 237. 161,162, 165 and 166 can be simple conductive contacts such as copped wire/films or any electrically conductive/resistive element including conductive rubber and polymers as well as any capacitive coupling setup/means/devices. Such capacitive coupling setup/means/devices can be as simple as having two metal surfaces embedded inside the tire in such position that when the tire is installed onto the wheel they are directly above each other and as aligned and as parallel to each other as possible so to form a capacitor whose dielectric is the tire's rubber compressed between the tire's beads and the wheel as described further below. 160 and 167 are means to connect 205 to 161 and 166 respectively. They are preferably but not necessarily made of conductive material such as copper or other metals or conductive polymers/rubbers. 163 and 164 are means to connect 206 to 162 and 165 respectively. They are preferably but not necessarily made of conductive material such as copper or other metals or conductive polymers/rubbers.

One embodiment of the invention whereby the tread level is sensed through projected capacitance sensing is shown in Fig 61 to 65. In this embodiment the sensor has a flat strip-like multi-layer structure as shown by the exploded view in Fig 63. An optional substrate 260 can be used to support the layers above and/or to provide on its bottom surface adhesive means so to stick during tire manufacturing the whole sensor onto the topmost tire plies/layers assembled before the final layers of rubber are added above the sensor. On top of 260 there is an electrically conductive area/pad 258 which forms one plate of a capacitor/capacitor-like/capacitor-behaving assembly. Above it there is layer/patch 253 which is ideally but not necessarily shaped the same as 258 (by way of example in Fig 63 rectangular with rounded corners) and smaller in size than 258 and positioned such that the gaps around 253's edges and 258's edges are as similar as possible. Above 253 there is a conductive plate 252. The shape of 252 is preferably but not necessarily similar to 253 shape. The size of 252 is the same or smaller than 253. 252 and 253 are aligned similarly as 253 is aligned to 258. 253 dielectric permittivity is such as to force most (ideally all) of the electric field lines 267 formed by the capacitor formed by plates 252 and 258 to flow through the tire rubber 261 whose level needs to be detected rather than through 253. 248 is a top layer cover to provide additional protection. Layers 249, 254, 255 and 259 provide isolation and/or support and/or means to keep all layers of uniform height and might be required in some applications but might also not be present as all and the stack is enclosed/encapsulated between 248 and 260 and all parts in between such as 252, 251, 250, 253, 258, 257, 256 are kept in place by adhesive means where required and the bottom surface of 248 and the top surface of 260 are attached together to add further stability to the structure. 251 and 257 are traces or similar means to connect the sensor's pads to pads 250 and 256 used for interface/connect to any electronics, in Fig 55 they are represented by 161 and 166. In the model shown by Fig 61 to 63 the main assembly has cut-outs 246 and 245 so that pads 250 and 256 can be accessed. Exposing 250 and 256 through cut-outs 246 and 245 is generally required in system configurations where the sensor connectivity is through direct contact (instead of a capacitive coupling connection) which is achieved by having holes through the tire rubber as shown by 13 and 26 so that external pins/contact can connect. If required the lower pad 256 can be made thicker to compensate for layer height, but because the layers are very thin this is rarely necessary.

Figure 64 shows a cross section of the sensor assembly shown in Fig 61 to 63. 264 represent the rubber over-molded on top of the sensor and 262 represent the cuts that form the tire's tread. The stack 265 represent the sensor stack and 266 represent the tire layers assembled below/before the sensor assembly/instalment such as steel plies and layers of other materials including thin layers of rubber or other compounds between them.

253 has a permittivity such that the capacitor uses the tire tread whose level needs to be sensed as the dielectric so that most of the electric field lines go through the tread's rubber volume 261. Because different tire rubber compounds have different permittivity values, different materials with different permittivity must be chosen for 253 to ensure that electric field lines go through 261 as shown by 267.

As the tire tread is consumed as shown by 268 the amount of rubber above the sensor is decreased and the capacitance value changes as symbolically represented by lines 269 (compared to initial 267). By knowing the capacitance values of the sensor at a given tread block height, by way of example when installed new, and the variation per unit of tread wear (by way of example 20 pF/mm of tread wear), which specific to tire tread shape, tire construction and tire materials, the tread level at any given time can be calculated/interpolated.

Fig 66 to 70 show a different embodiment of a capacitive version of the sensor. The basic principle is similar to the one previously described but instead of the two plates above each other they are next to each other. The layer stack and configuration can be clearly seen in Fig 68. 280 is a substrate which provides support and/or means to attach/stick to the tire layers 266 below it. 279 is a layer of a material/compound with a specific permittivity to do direct the electric field lines of the capacitor forming plates 275 and 275 in the preferred/desired direction/volume (i.e. the tire tread block whose wear need to be monitored/measured). Pads 275 and 276 in this configuration are co-planar. 278 isolates pads 275 and 276 from each other and if made of a material which is the same or similar to the one 279 is made of, it can further contribute to direct the field lines vertically up and through the tire tread block to be monitored instead of sideways avoiding this way fringing effect which even if negligible are always preferred to be avoided. Top layer Til provides protection of the sensor and add rigidity. Similarly to Fig 64 and 64, Figures 69 and 70 show a cross section of the sensor's sensing area with the capacitor field lines 281 and 282 travelling between the two plates 275 and 276 and through the tire tread rubber block 261. As the tire tread is consumed by a certain amount as shown by 268 the amount of rubber above the sensor is decreased and the capacitance value changes as symbolically represented by lines 283 (compared to initial 281 and 282). By knowing the capacitance values of the sensor at a given tread block height, by way of example when installed new, and the variation per unit of tread wear (by way of example 20 pF/mm of tread wear), which specific to tire tread shape, tire construction and tire materials, the tread level at any given time can be calculated/interpolated.

Depending on the tire rubber compound, tread shape and depth and other parameters including temperature, the variation in the capacitance change linearity can vary so the electronics used to calculate the tread level might need to use look-up tables to interpolate/correlate sensor readings to tread wear.

Fig 66 to 68 show a sensor configuration whereby the connectivity to the external electronics is achieved through capacitive coupling rather than conductor (i.e. copper) connectivity. This can be seen by looking at Fig 66 where the electronics interface pads are embedded/hidden below the top layer without any cut-outs (contrary to 245 and 246 of the previous sensor description) but are shown by the dotted lines 271 and 272 in Fig 67. 271 and 272 each form one pad of a capacitor whose respective other pad is in the substrate/flexi-strip attached to the wheel the tire is mounted on. The dielectric is the rubber compressed between such pads by the tire beads compressing it onto the wheel rim. 271 and 272 are represented by 161 and 166 in Fig 55.

A sensor can have a sensing element setup as per Fig 61 to 63 and have either the connectivity means shown in those figures (i.e. conductive metal contact to external electronics) or have the connectivity means shown in Fig 66 to 68 (i.e. capacitive coupling non-exposes pads). Equally, a sensor can also have a sensing element setup as per Fig 66 to 68 and have either the connectivity means shown in those figures (i.e. capacitive coupling non-exposes pads) or have the connectivity means shown in Fig 61 to 63 (i.e. conductive metal contact to external electronics).

Top layers Τ1Ί and 247 can have cut-outs just above the sensing element pads so that the tire rubber comes in direct contact with either one or both of the sensor pads, this might be done to avoid variation in dielectric constant/permittivity above the sensing pads. Where a cut-out is present, to further direct the field lines into the tire tread block, Til and 247 can also be made of special compounds that further increase field line directivity.

Figures 71 to 75 show an embodiment of an inductive version of the sensor. In this embodiment the sensor has a flat strip-like multi-layer structure as shown by the exploded view in Fig 73. A bottom substrate 294 provide support and means to attach the sensor stack to the tire topmost plie before the layers of rubber forming the tread are layers above said sensing device. A coil 291 is the main sensing part and has connectivity pads 289 and 290 via traces 287 and 288. Such pads can be exposed so to be used for direct electrical contact as shown by 304 (similar to principle shown by 302) or be not exposed such as when used in capacitive coupling connectivity (similar to principle shown by 303). Isolation 295 and 295 might be required to provide isolation is the wire is not electrically isolated (i.e. enamelled wire or similar). Top layer 292 provide additional protection to the sensor coil. Above the sensor and inside the tread volume to be monitored is placed a volume of material 311, 301, 298 different from rubber and such that its volume and/or variation of affects the inductance/characteristics/behaviour of coil 291. Such material is preferably magnetic or ferromagnetic or ferritic or ferrites or generally any material affecting magnetic fields/lines and/or inductor/coil performance/characteristics/behaviour/sensitivity. Such material is placed in a recess 309 of the tread 308. Such recess can be carved out after the tire tread has been molded or it can be molded directly when molding the tire tread. The newly inserted material can be press fit and/or glued in place or molded/cast/potted into the hole/recess 309.

In figures 74 and 75 showing cross section 307. In fig 74 can be seen that magnetic lines 299 are formed by the coil 291 and travel mostly (i.e. tend to be concentrated) in the inserted material 298. When the tire tread is consumed as shown by the amount 268 in Fig 75, the volume of 298 is reduced to the volume of 301. Such reduction in volume affects the coil characteristics/inductance/behaviour. Such change and new characteristics are then measured by the electronics and interpolated so to correlate the new readings to the new tire tread depth.

The same tire tread void 309 used for the inductive sensing solution described above can also be used in the inductive sensing solutions described by Figures 61 to 70. In this scenario the void/hole 309 is filled in with a material shown by 311 which has characteristics/permittivity such that it favourably the sensitivity and/or other characteristics of the capacitive sensors described in figures 61 to 70.

The sensor assembly can be installed asymmetrically as shown in Fig 59 by 239 whereby all the contacts are on one side. This solution is useful for systems which interface/connect with the electronics placed on one side such as when the electronics is part of or enclosed in a TPMS unit. Alternatively the sensor assembly/strip can span across the entire tire width as shown by 240. As it travels down the side walls of the tire, the sensor strip/assembly can be stopped at any point that is convenient for a reliable connectivity or fold over the tire beads' edges as show by 241.

To achieve the connectivity between 237 and 238 shown in Fig 55, 242 and 243 can be electrically exposed through the sensor assembly and through the tire rubber to provide a direct resistive electrical connection (by way of example through copper wire/connectors) to the electronics. This can done by having holes in the tire walls as shown by 13 and 26 exposing pads 241 and 242 or by having wires like 36 which are connected to 242 and 243 (or the sensor sensing pads directly) and which exit through the rubber as shown by 43 in Fig 14.

Alternatively, to achieve the capacitive coupled connectivity between 237 and 238 shown in Fig 55, 242 and 243 can be embedded under the sensor's assembly top layer and/or under the overmolded tire rubber. A capacitive coupled connection to the electronics is then created as previously described.

Positioning of the sensor is such that the sensing element is preferably but not necessarily directly below the tire tread block to be monitored.

The flexibility of the whole stack including the conductive layers/materials/traces is ideally matched to the tire's flexibility to ensure smooth riding.

A tire can contain one or more of any of the sensors described in the application. Each sensor can be connected independently to the electronics. Alternatively, any sensor can be connected to any other sensor and/or to the electronics as to form a network of sensors of same or different types to sense tire tread wear in different areas of the tire.

In this document RTTS stands for Resistive Tread Threshold Sensor, SCTD is short for Sharp Conductive Threshold Detector and CTLS is short for Capacitive Tread Level Sensor. Such abbreviations and what they are short for do not necessarily reflect their functionality, but are just used to refer in a more concise way to whatever system/device/unit/assembly they have been used to describe further below.

In this document the word conductor includes, wherever possible, good and poor conductors (including elements, alloys and compounds), semi-conductors and any conductive compound such as conductive rubbers and conductive plastics.

In this document 205 can be an RTTS, SCTD, SCTD with series resistor, CTLS or any combination of any of them. RTTS, SCTD, SCTD with series resistor, CTLS and all practically possible combinations of any of them are all subject of this patent. Design, implementation and functioning of RTTS, SCTD, SCTD with series resistor, CTLS and some practically possible combinations of some of them are described in detail below.

160,167, 163 and 164 are in this document generally referred to flexi-strips and more specifically 160 and 167 are in this document referred to as tire flexi-strips (TFS) and 163 and 164 are in this document referred to as tire wheel flexi-strips (WFS). Design, implementation and functioning of TFS and WFS are described in detail below.

161,162, 165 and 166 are contacts, connectors or any other means to connect/couple/interface 237 and 238 with/to each other and/or other systems/devices.

237 and 238 subsystems and preferably but not necessarily preassembled sub-assemblies. 237 is in this document generally referred to TSID (Tread Status Feedback Device)

Generally speaking some or all of the functionality of 206 can be implemented inside the same 205 enclosure or as part of a single assembly (by way of example assembled onto a shared/single support). In other words 206 might contain its own TECU and/or be connected to a TPMS sensor by way of example only like those usually installed in a wheel's valve. Such configuration might in some implementations make 160,161, 166 and 167 redundant and result into 205 being a complete system which might also include its own means to generate and/or store electrical power to be used by any part of such system.

As illustrated in Fig. 1 a tire is composed of various parts such as one or more body plies 10 (here for simplicity just one is shown) and a number of other layers such as a steel belts 9 and cap plies 8 (for simplicity again just one of each is shown), beads 19, one or more layers of rubber which cover the plies/belt assembly/stack. Depending on the tyre design and construction a different number and/or different types of plies might be part of the tire and might be placed at different places within the tire. A number of tread grooves such as 2 are recessed from the outer surface of the tyre 1 forming a number of blocks such as 3. The sidewall 5 extends from the tire shoulder to the area 7 that comes in contact with the wheel 59 and is not directly or easily accessible when the tire is mounted on the wheel. The area 6 indicates an area along the tire which is above 7 and generally exposed to the outside when mounted onto the wheel, such area is relatively easily accessible when the tire is mounted onto the wheel. The rubber above and below the plies can be made by a number of layers of different compounds, that is especially the case for the rubber 4 above the plies.

A sensor assembly/unit/device 11 (such as any represented by 205) is positioned preferably (but not necessarily) above the topmost ply 8 in such a way that it can detect the amount of wear of one or more blocks such as 2 and/or it can detect whether a certain level of wear of blocks such as 2 is achieved. Preferably 11 protrudes into a tread block such as 1 in such a way that at least part of it is above tread surface 2. One such arrangement would result into the gap 178 between the top surface of 11 and top surface of block 1 to be less than the tread/block depth. As the tire is used the tread wears out and when the tread is removed due to wear gap 178 decreases until it becomes null. From such moment on, sensor 11 begins to be affected by additional wear (of the tire hence of 11). This can happen in a number of ways depending on the sensor type. The various sensor types, designs, construction, features and how it works are a major part of this patent and are explained in detailed elsewhere this document. Important to notice that a tire can have a number of such sensors placed in any arrangement and in any position of the tire and any of them can be connected to any other one.

The sensor ideally but not necessarily, interfaces to a number of devices which detect its status and/or changes of its status/characteristics/properties and ideally transmit such information to the outer world (i.e. other devices such as a vehicle's key fob network or wireless system) so that information can then be relayed to the user. Such device/s the sensor is connected to (referred to TECU for Tire Electronic Control Unit) can be housed inside the sensor itself (i.e. integrated) or placed remotely (i.e. outside of the sensor or sensor assembly) onto/into the tire or into/onto the wheel. Due to vibrations, it is preferable to have any sensitive electronic components away from the tire due to the tire continuous flexing, vibrating and stressing. The TECU is preferably housed inside an enclosure such as 50 or 60. Alternatively the TECU can be part of and/or be housed in and/or be connected to a TPMS sensor such as, by way of example only, those usually installed in a wheel's inflating valve. 50 shows an example of a TECU mounted inside the tire's pressurised chamber while 60 shows an example of TECU positioned outside the pressurised volume and onto the inner circular surface of the wheel. Any position where the TECU can be positioned/attached is covered by this application. They include any purpose designed recesses in the wheel itself.

The sensor 11 is connected to an external TECU via any means which can do such function including but not limited to conductive wires (including elastic conductive materials and compounds), flat conductors (such as foils, thin bars, braids), flexi-strips, flexi-PCBs, flexi-PCBs-like assemblies as shown in Fig 1 and 2 where the two traces 14 travel from the sensor 11 above and along 8, 9 and 10 down the sidewall of the tire (inside and fully protected by the rubber) and reach areas 6 of the sidewall where holes 13 allow some of the conductors 14 surface to be exposed so it can be connected to a TECU (or any other devices). Devices such as those shown in Fig 50 and 51 can be used to then connect to 13 and other external electrical/electronic devices such as TECUs.

To ease assembly, conductors 14 can be mounted on a supporting flexible substrate 18 similarly to a classic flexi-PCB type assembly (a flexi-PCB can be used and is covered in this application). In such flexi-strip, flexi-PCB or flexi-PCB-like type of assembly the substrate 18 as well as providing electrical isolation between the two conductors 14 can also have means to keep it (and the sensor 11 too if mounted on top of the flexi-PCB) in place during tire manufacturing process, mainly after having been attached onto/above the (ideally) topmost ply and during the subsequent stages such as the application of additional rubber compounds layers and/or tread molding/forming. This is important because during tread molding the sensor might move. Such means to keep it in place include adhesive compounds/backings and any other compound which when serve such purpose (i.e. by reacting with the surface where such flexi-PCB is mounted on. Alternatively, 11 can be mounted onto a lower/inner layer such as any of 9 or 10 and holes through the layers above the layer where 11 is mounted on allow 11 to protrude through them so that its ideal final position is reached and maintained. This latter solution might also help keep 11 more securely in position during tire manufacturing and use.

TFS such as 14 can also carry on along 10 so that instead of, or as well as, being exposed through holes 13, they are exposed internally to the tire (i.e. in the pressurised chamber) through holes 26 through the internal tire rubber 44.

There are a number of applications where more than one sensor and/or more than one TECU are preferably used. In such cases sensors like 11 can be positioned anywhere in the tire and any of TECU can also be placed anywhere in/on the tire and/or in/on the wheel. In such cases of multiple sensors and/or TECUs each sensor can be connected to just one TECU or to more than one TECU. Also each TECU can be connected to one or more sensors. Any other combination is also covered.

Sensor 11 can be implemented in many ways each providing different advantages. Some are described below by way of examples.

Another embodiment of the present invention is illustrated in figure 6 where at least a part of a conductor is placed in such a way and position that when the tire tread reaches a certain level of wear such conductor is altered in a way which can be detected by one or more electronic circuits or by any other means. Such alteration includes breaking (electrical interruption) and/or variation in its properties/characteristics including but not limited to resistance.

Details of one such implementation can be seen by way of example only in figure 6 where a conductor is in this case a single component (such as copper strip) comprised of 28, 20, 22, 24 and 25 and it is routed above some means 21 which keep at least one part 22 of such conductor in a position that is such that when the wear of the tire's surface 1 reaches a certain level such as the top surface of 22 the conductor starts wearing too, ideally at the same rate as the tire's surface/compound and when the tire and conductor wear reach a second point such as surface 180 the conductor continuity is interrupted.

For example as the tire wears, surface 1 lowers towards surface 2 effectively decreasing the height of block 3. As this happens, a point in tire wear is reached whereby surface 1 is at the same height as the top surface of 22, in other words the top surface of 22 start being exposed. From this point on as tire wear increase then 22 starts wearing too causing some of its characteristics (for example the resistance) to start changing. Such change is more or less detectable depending on material used in the affected area. As wear continues, eventually 22 is broken causing the conductor to be interrupted. The variation in the conductor characteristics such as resistance and/or its breaking/interrupting can then be detected by a connected electronic device such as TECU which monitor the conductor's continuity and/or resistance. Such information can then be relayed to a vehicle's wireless network so to monitor the tire's wear.

For the purposes of this document the sensor-strip is defined as the topmost part of the sensor which can be affected and ideally when a specific tread wear reached completely cut. By way of example ony, with reference to Fig 7 the sensor-strip is 22 and in Figures 9 and 11 it is represented by 30. For the purposes of this document the sensor-assembly comprises any and all parts of the sensor which are assembled together to provide the required sensing functionality and it includes the sensor strip and any means/supports/devices which keeps it in the desired position. It can also include part of a TFS and or not. By way of example only, in an implementation such as that shown in Fig 7 the sensor-assembly would include the sensor-strip 22 and support 21 and any other part the conductor which comes in contact with 21. By way of example only, in an implementation such as that shown in Fig 9 and 11 the sensor-assembly would include the sensor-strip 30 and support 21 and any other part of the conductor which comes in contact with 21.

By way of example only, with reference to Fig 6 TSID comprises the sensor assembly, 20, 24, 25, 28 and 21 (depending on the context 21 may or may not be included - the broadest practically implementable is always assumed).

Parts such as 20 together with 28 and 24 together with 25 which connect the sensor assembly to any device or electronic (monitoring) system in/on the tire or off the tire are from now on referred to as the connecting-legs or simply legs. To differentiate a connecting-leg or just leg from a TFS, a connecting-leg includes the connector/pads/contacts such as 28 or 25. So 20 and 28 form one leg and 24 and 25 form another leg. The entire assembly of the sensor assembly and the legs is in this document referred to as the Tread Status Information Device or TSID for short.

Ideally but not necessarily, any and all parts of the sensor which are above surface 2 wears at the same or similar rate as the tire compound (radially outwards) above it. Ideally but not necessarily, any and all parts of the sensor which are above surface 2 behave mechanically (i.e. compression, bending, twisting etc) similarly to the tire compound (radially outwards) above it.

The sensor, especially its sensor-strip, can have any practical amount of resistance, from very low (such as copper) to very high and it can be made of metals, alloys or any conductive compounds including conductive rubber and conductive plastics. Semiconductor compounds/materials can also be used.

More than one sensor strips and sensor assemblies can be integrated anywhere into a tire allowing the detection of wear of different parts of the tire. Each of them can be connected in series or in parallel to any other or any practically possible combination of series and parallel. Elsewhere in this document examples will describe such implementations explaining their advantages.

Ideally, but not necessarily, the sensor strip, the sensor assembly and any other part of the TSID has mechanical characteristics such that it affects minimally (or ideally not at all) the deformation of the tire and/or its performance especially during use and such that the performance of the TSID (especially the sensor strip and sensor assembly) is affected minimally or not at all by the tire changes (such as deformation, temperature, etc) especially during use.

is a structure or device which keeps the sensor-strip in a specific position during and/or after tire manufacturing. One implementation of 21 is just a simple block to which a sensor strip is attached or coupled by any mean whatsoever.

Ideally one or more parts of the TSID (especially the conducting parts) is elastic to allow flexing during tire manufacturing and use. The elastic characteristics ideally match as close as possible that of the tire rubber layers above it.

Sensor-strip 22 sits on top of surface 180 of 21 and is kept in position by the compounds layered over it such as the tread-forming layer of rubber and/or any other layers of rubber above it. Preferably but not necessarily, 21 becomes malleable at a temperature higher than the compounds layered above it. This is so it is not deformed by subsequent tire manufacturing processes.

By way of example the any or all parts of legs 20 and 24 might be conductive foil or braid (ideally but not necessarily flat type) which when placed in position during manufacturing are in a relaxed state but which, being braided, can be slightly stretched during the various manufacturing processes and during tire use, without braking. 22 and the segments connecting 22 to 20 and 24 can be exactly the same braided conductor effectively forming one single long braided conductor. 22 and the segments connecting 22 to 20 and 24 could alternatively be a rigid conductor such as a single metal foil or sheet/bar.

Figure 9 shows by way of example yet another implementation whereby one single conductor forms the entire TSID and for most of its length it is zig-zag shaped to allow different stretch/positioning at different points during manufacturing and use. By looking at legs 29 and 31, such stretch is symbolically represented by leg 31 being stretched as shown in point 32 where a couple of zig-zag segments have been straightened up. The TSID conductor can be single strand or multi strand or a braided conductor.

Figures 9,10, 12,13 and 14 also shows another type of tire connector whereby the TSID conductor/legs at some point exit the tire assembly through the rubber laid above them as shown by 43 in such a manner as to allow the extra external conductor length to become/form the tire connector (i.e. means to electrically connect to a device/system outside the tire such as symbolically represented by 161 and 166 in Fig 55).

One way to create connectivity between tire and wheel is shown in Fig 13, 14, 15, 16,16, 17 and 18 where the parts of the legs which are external to the tire can be positioned roughly as shown by 35, 36 and 37 while the tire is assembled onto a wheel 59 (as shown by motion indicated by arrow 58) to form the tire connector contacts which mate with the wheel's connector contacts 48 and 54 (symbolically represented by 162 and 165 in Fig 55). Once the tire is fully assembled onto the wheel with the tire connectors contacts correctly aligned to the wheel's connector contacts an electrical circuit is then formed together with WFS 49 and 53 (containing connectors 48 and 54) and device 50 (symbolically represented by 206 in Fig 55). Once the tire is securely in the correct place the excess of 37 can be trimmed away to avoid being pulled and/or short-circuiting with other metal parts including the wheel itself.

Flexi-strips can be flexi-PCBs or flexi-PCBs like type of assembly/stacks. Examples of flexi strips are shown in Fig 40, 41, 42, 43, 44 and 45 and are discussed in a separate part of this document. One important implementation of the flexi-strips is that it can be made of rubbery or soft material (to improve sealing and adaptation to the non-flat surfaces on the tire and wheel) and the top surface or top layer made of a conductive material including any conductive rubber. This is shown by 65 and 66 where there are no exposed metal contacts but instead the full top surface is conductive (having any conductivity value practical for the application). The bottom most layer ideally is isolating material to ensure the wheel it is coupled does not electrically interfere in undesired ways.

Ideally the bottom layer is a strong adhesive layer to bond securely and hold firmly in place the flexi strips onto the wheel internal surfaces such as 47. Having the flexi-strips strongly bonded to the wheel is very important because at high speed the centrifugal forced exert considerable forces which on the long term could result into the flexi strips detach from the wheel if not strongly bonded to it. If The same forces could also have the same effect onto the electronic unit/device such as the TECU 50 placed inside the pressurised tire chamber, so given the potentially higher mass of 50 an additional restraining band 52 is used and wrapped on top of 50 as shown by 51. 52 ideally but not necessarily runs all around the wheel in a single ring-shaped arrangement. 52 can be, or have an adhesive on its bottom surface, the one coming in contact with 50 and wheel's inner surface 47.

With reference to Fig 16, exposed contacts such as 54 are ideally kept as short as possible as shown by the area 55 being isolating material (i.e. not a contact) and ideally also soft to ensure air-tight seal of the tire pressurised chamber in that area.

Once the tire is securely installed onto the rim (ideally after the tire is inflated) the excess flexi-strip length such as 56 can be trimmed away to both improve aesthetics and reduce the risk of the flexi being damaged or pulled or it shorting onto the wheel.

Fig 20 shows an implementation whereby the TECU 60 is mounted externally to the pressurised chamber and inside the wheel where the spokes join the wheel. In this configuration the flexi-strip is wrapped around the wheel's edge as shown by 61 and follows the wheel inner surface as shown by 62 to reach TECO 60.

In Fig 21, 22, 23 and 24 the flexi strips are connected to a TECU external to the pressurised chamber and in order to keep the flexi-strip mass (hence centrifugal forces) to a minimum it is kept as narrow as possible as it crosses the internal surface 47.

Fig 25 and 26 show flexi strips which have multiple contacts for each side. This configuration might come useful or required when tires with more than two tire contacts are used, for example with tires with multiple sensors or for redundancy.

Figures 27, 28, 29 30, 31 and 32 show a capacitive coupled solution/system where the tire connectors together with the flexi-strips provides capacitive coupling between the TECU and the TSID. To explain this in context of the general block diagram in Fig 55, instead of 162 and 166 connecting/coupling to 162 and 165 respectively in a resistive manner - such as any classic metal contacts connector - they are connected capacitively (i.e. exercising a capacitor-like behaviour). This solution ensures a very tight air seal between the tire and the wheel. Capacitive coupling is achieved by forming one or more capacitors between the tire and one or more of the flexi strips in the area where they come in contact with each other.

One such implementation is by having at least one plate like 84 (or 85) of such capacitor inside the tire's bottom edge outside any conductive material/parts such as 10 and at least a second plate of such capacitor incorporated into the flexi-strip and being as co-planar as practically possible to the first 84 (or 85) such as surface 92. The insulator of such capacitor is then formed by any non conductive materials/compounds between such plates when the tire is assembled onto the wheel. This include any tire compounds/layers between the two plates forming the capacitor such as area/volume 86 and any compounds/layers above the flexi strip plate.

A variant of such implementation is one whereby the flexi strip top surface is conductive so only the tire provides an insulator to contribute to the capacitor. In this case the top surface and/or layer could be metal or metallic or metallised material or any other conductive material or compound including conductive rubber, conductive rubber-like materials and conductive soft compounds or materials. This can be seen in Fig 31 and 32 where a flexi strip with a conductive top surface or layer 88 (or 91) form the plate of a capacitor whose second plate is formed by 84 (or 85) and the insulator of such capacitor is formed by 86 (or 189). In Fig 31 and 32 the bottom of the flexi-strip is electrically isolated from the wheel by one or more layers of adhesives and insulators or insulating adhesive.

The same drawings can be used to represent an alternative version where the flexi strip contains as part of the flexi strip stack assembly/construction a conductive layer in the area 88 (or 91) running as co-planar as possible with tire plate 84 (or 85) and below the flexi-strip top insulating layer which ideally but not necessarily is also relatively soft contributing to create an air tight seal. In this configuration the insulating layer contributing the capacitive coupling is not just 86 (or 189) but also any insulating material on the flexi-strip.

Generally speaking, the shape and area of the flexi-strip capacitive coupling plates/surfaces and the tire capacitive-coupling plates/surfaces are ideally optimised to achieved the desired level of capacitance. Guidelines to achieve this include minimise the thicknesses of insulators 86 (and 189) between plates of the same capacitor, increasing the area of the plates and keeping as much area of both plates as co-planar as possible. The tire can be made using a (rubber) compound in the capacitor forming area/volume with dielectric characteristics which are different from the main rubber used. Such implementation of a different rubber type used just in this area or general in the area all around the tire which covers the bead core, such as the protection strip, is also covered in this application.

In this capacitive coupling connectors configuration, a circuit is created whereby the sensor which can act as a resistor and/or switch (i.e. opens a circuit when area 22 is broken due to tire wear) is connected in series with a number of capacitors (the capacitive coupling connectors just described ideally two - one for each leg) and fed into the TECU so that a signal can be fed into it and monitored. Breaking 22 and/or affecting its characteristics (such as its resistance) affects the circuit behaviour resulting in the TECU detecting conditions such as tread wear beyond a certain level. The simplest implementation is to detect that the two capacitors (formed by the tire and wheel coupling as just described) are no longer connected when the sensor-strip which connect them is broken due to tire wear over a certain limit.

Figures 33 and 34 show a flexi-strip configuration with more than one contact on the same side of the wheel and shortened from the edge of the wheel's rim in order to allow part of the tire sidewall to seal against the wheel's rim in the area 93.

Figure 35 and 36 represent a flexi-strip with a conductive top layer/surface or a capacitive-coupling type flexi-strip as previously described or any other type of flexi-strip assembly/design whereby when installed it does not reach the wheel's rim effectively leaving an area 93 exposed for direct contact with the tire's wall to ensure air-tight seal of the pressurised tire chamber.

Figure 38 shows a configuration where a sensor-strip 68 is kept in a certain position such as at the level of surface 130 by any means during manufacturing including placing a block in the volume 73 under it or by any other means including keeping 68 through supports connected to it from the outside of the tire which are then removed at a later stage.

This TSID can be implemented with a flexi-PCB type of assembly where both contacts are exiting the tire on the same side and the entire TSID is wider and more robust. In this configuration legs/conductors 69 and 70 are separated along most of their length by insulating strip 71 which can be part of the same assembly and they are then joined at the sensor-strip point 68.

Flexi-strips can be flexi-PCBs or flexi-PCBs like type of assembly/stacks. Figures 40, 41, 42, 43, 44 and 45 show examples of various types of flexi-strips.

In Fig 41 a top layer 108 separate traces 106 and 107 from each other and insulate them from the outside environment for most of their length apart from apertures 104 and 105 which provide contact means to the tire connector. 109 provide a substrate for the traces 106 and 107. 110 is an optional backing support and 111 is a layer which provides means to attach the flexi strip onto any surface such as the wheel's.

In Fig 43 a similar assembly/stack as to that of the flexi-strip shown in Fig 41 is shown. The main differences are that a greater aperture of the layers above the conductors (such aperture extending to the sides over insulating layer 119) and the topmost layer being a deformable layer which contributes to providing an air-tight seal of the pressurised tire chamber. 120 provide a substrate for the traces 116 and 117. 121 is an optional backing support and 122 is a layer which provides means to attach the flexi strip onto any surface such as the wheel's.

Fig 45 shows a see-though view of flexi-strip assembly/stack for a capacitive-coupling solution/interface/connection. A conductive plate 124 is embedded below a protective and isolating layer 125 and is connected to conductive connections/traces/wires such as 126 and 123 which carry any electrical signal wherever else required. 125 is also ideally, but not necessarily, easily deformable/compressible to contribute to an air-tight seal of the pressurised tire chamber. Layer 125 also contributes to create the insulating layer of the capacitive assembly together with the tire's insulating layers such as 86 and 189. Insulating layer 128 further protects and insulate the conductive traces/plate and together with 126, 123 and 124 maintains the general layer's thickness relatively constant. 127 is a backing layer whose bottom (i.e. exposed) surface can also have adhesive means so to be attached onto the wheel's surface 47.

In order to further increase the quality of the air tight sealing of the pressurised tire chamber the flexi-strip ideally, but not necessarily, has chamfer and/or filleted edges as shown in Fig 46 and 47. Such chamfers and/or fillets can run along the entire flexi-strip length or just along a certain length such as 191 which is the portion compressed between the tire and the wheel's rim. Lines 192 are highlighted to show one possible profile where the chamfered edge is also filleted.

Figure 48 shows a sensor assembly where the sensor is coupled/mounted onto a supporting base structure such as, by way of example, a flexi-strip. Two conductive plates 135 and 151 form a capacitor-like structure/device (in this document referred to as CTLS) together with insulating material 141. The plates 135 and 151 are electrically connected to the flexi-strip contacts 143 and 142. Such connection can be made by way of example through a welding or soldering joint 150. Contacts 143 and 142 are connected to traces 145 and 144 which in turn can be connected to other parts of the TSID. Layer 146 provides protection and insulation of the traces 145 and 144. Layer 147 provides mechanical support and interface for the traces and layer 148 provides adhesive means to couple the structure above it to any tire surface as required (by way of example when positioned as shown in Figures 1, 2 and 4). The capacitance of the CTLS shown in Fig 48 is monitored by a TECU.

When the tire tread wear has not yet reached surface 136, the capacitance (measured) across/between 135 and 151 of the CTLS has a certain value. As the tire tread wear increases it reaches a point where it starts wearing out the top surfaces of 135,151 and 141 (i.e. surface 136), which results in change of capacitance due to the variation of the dimensions (such as height 140) of the CTLS from its original values. By measuring this new capacitance value and/or the variation of capacitance from the original value, the amount of wear of the CTLS, hence of the tire tread, can be estimated/measured/calculated.

Figure 49 shows a sensor assembly where the sensor is coupled/mounted onto a supporting base structure such as, by way of example, flexi-strip. Two conductive plates 193 and 194 are connected on different and ideally opposite sides of a resistive material/compound 196 to form a resistive structure/device (in this document referred to as RTTS). The plates 193 and 194 are electrically connected to the flexi-strip contacts 154 and 155. Such connection can be made by way of example through welding or soldering joint such as 150. Layer 152 provides protection and insulation of the traces such as 156. Layer 157 provides mechanical support and interface for the traces and layer 158 provides adhesive means to couple the structure above it to any tire surface as required (by way of example positioned as shown in Figures 1, 2 and 4. The resistance of RTTS (i.e. of the block 196) is monitored by a TECU. When the tire tread wear has not yet reached the top surface 195 of the resistive block 136, the resistance measured between/across 193 and 194 has a certain value. As the tire tread wear increases it reaches a point where it starts wearing out the top surfaces of 193,194 and 196 (i.e. surface 195), which results in change of resistance across/between 193 and 194 due to less material/compound being present compared to the initial amount when the tire hence the RTTS was new. By measuring this resistance value and/or the variation of such resistance from its original value, the amount of wear of the RTTS, hence of the tire tread, can be worked out or estimated.

The accuracy of CTLS and RTTS measurements/detection may vary depending on their construction (including materials, tolerances etc) and the tolerances of their position within the tire so either of them can be used in conjunction with a SCTD sensor (such as those shown in Figures 11 and 7) so to measure progressive tread wear (through CTLS and/or RTTS) as well as detect when the tread reaches a specific (maybe critical) threshold (through SCTD). To keep connections to a minimum the RTTS and/or the CTLS could be connected in series with the SCTD providing a single two-wire interface to external devices such as any TECU they might be connected to. A number of RTTS, CTLS and SCTD can be connected together to achieve better overall performance and/or compensate each-others tolerances or weaknesses. A number of RTTS, CTLS and SCTD can be housed in a single housing and/or pre-assembled onto a support which provides electrical connectivity/interfaces to external systems. Example of one such configuration is shown in Fig 52 and 53 where a RTTS or CTLS sensor 197 is connected in series with a SCTD 199 made of a supporting block 201 and sensor-strip 200 and both assembled onto a flexi-PCB or flexi-strip 198. It can be seen from the picture that the SCTD 199 is connected in series with RTTS or CTLS 197 through conductive traces 202, 203 and 204. Trace 202 is connected to one of SCTD terminals whose second terminal is connected to trace 203 which in turn is connected to the first terminal of RTTS or CTLS sensor 197 whose second terminal is then connected to trace 204. This configuration connects 199 and 197 in series so that as long as the SCTD sensor strip is uninterrupted (with its resistance ideally very low) it effectively electrically connects the two 197 terminals directly to traces 202 and 204. This allows the RTTS and CTLS characteristics to be measured by any connected TECUs. The moment SCTD sensor strip is broke (for example when the tread wears below the top surface of 201) then conductivity of SCTD is interrupted effectively isolating 197 from the rest of the circuit and resulting into the TECU detecting this condition.

One example of the connectivity just described is shown in Fig 54. Where trace 202 is represented by connection 209, SCTD 199 by 210, trace 203 by connection 211, RTTS or CTLS 197 by 212 and trace 204 by 213. 214 represent the flexi-strip and 207 and 208 represent connections/pads such as tire connector's pads/contacts. It can be seen that 212 keeps working only until 210 is broken (for example by tread wear).

Sensors, especially RTTS and SCTD can be connected in series or parallel to detect tread conditions/wear-status in various parts of the tire while minimising connections to TECUs. Examples of series connections are shown in Fig 56 where each of 167, 169 and 171 represent a RTTS or SCTD or combination of both connected as shown in Fig 52, 53 and 54.

RTTS, SCTD and CTLS can also be connected in parallel again to monitor tread wear/status in different areas of the tire by placing each of them in separate points in the tire. This is schematically shown in in Fig 57 where each of 216, 217 and 222 represent RTTS, SCTD or CTLS or a configuration as shown in Fig 58. Fig 58 represent a series connection of a SCTD 231 with a resistive element 233 connected in series through connection 232 and to the outside network through 230 and 234. This configuration is particularly useful in a parallel connection configuration such as that shown in Fig 57 because it allows to detect that one or more of the SCTD has be triggered (i.e. its sensor strip has been broken). Resistors can be all the same value or different values. By providing different values, and measuring the total network resistance the TECU can clearly derive/work-out which of the sensors has been triggered.

All possible combinations of series, parallel and series-parallel connectivity of each sensor type (RTTS, SCTD, SCTD with series resistor, and CTLS) is covered by this patent application.

SCTD sensor can be made by placing a conductive (or resistive) strip/wire/braid/foil/conductiverubber/conductive-plastic or similar such as 200 on top of a block 201 as shown by way of example by SCTD 199 in Fig 52 and 53. Alternatively any part between the two terminals of 199 can be any conductive (or resistive) materials/compounds electro-deposited or spray-painted or deposited in any other similar way. 199 can also be made by applying/adding any or all conductive parts/surfaces/areas through LDS technique (Laser Direct Structuring) ideally onto a support such as 201.

Figures 50 and 51 show means of connecting contacts such as 26 or 13 to a flexi-strip 185 through pins 183 (ideally springy or spring-loaded) which then can be used in the various ways as described previously in the various examples. Surface 184 can be coated with adhesive means and/or designed so that it can be attached to tires external surfaces such as 5, 6, 7 or 44. Such attachment could be achieved also by melting such surfaces and 184 together.

Claims

1. A vehicle tire tread wear sensing device and system comprising at least one sensing part embedded inside the tire preferably above any conductive plies/layers in such way that said sensing part's capacitance and/or resistance and/or impedance and/or inductance and/or continuity are affected by the depth/height/level of tread that said device monitors and means to connect/interface said sensing device to external electronics that by measuring said sensing device characteristics/response/status can derive/interpolate/calculate/estimate the level/height/depth or amount of wear of said tread

2. A vehicle tire tread wear sensing device and system comprising at least one sensing part made of a wire/foil (22, 30) embedded inside the tire so to protrude into at least one tread block in such way that said conductor's electrical continuity is interrupted when the tire tread wear reaches a certain threshold and means to connect said sensing part to external electronics which can read said sensor's state.

3. A vehicle tire tread wear sensing device according to claim 1 comprising at least two capacitor-forming plates and such that once embedded inside the tire the tread (261) level sensing is achieved mostly through measurement of the capacitance (and variation thereof) of said two conductive plates (252, 258) vertically aligned with each other and with the portion of tire tread such sensor monitors and with the insulator layer (253) between such plates which has a permittivity such that the capacitive field lines (267) go/direct mostly upwards/outwards through the tire tread block above the sensor rather than directly through said insulator layer and where the sensor's topmost plate (252) is smaller in size than the bottom plate (258) and the insulator layer (253) covers at least all the area projected by the top plate onto the bottom plate but also leave a preferably uniform gap around the edge so to project the capacitance field lines go from the top plate's top surface outwards into the tire tread block and back down into the bottom plate's top surface.

4. A vehicle tire tread wear sensing device according to claim 1 comprising at least two capacitor-forming plates and such that the once embedded inside the tire the tread (261) level/depth/height affects the capacitance between said two conductive plates (252, 258) vertically aligned with each other and with the portion of tire tread that said sensor monitors and with the insulator layer (253) between said plates which has a permittivity/characteristics such that the capacitive field lines (267) go/project/direct mostly upwards/outwards through the tire tread block above the sensor rather than directly through said insulator layer and where the sensor's topmost plate (252) is smaller in size than the bottom plate (258) and the insulator layer (253) covers at least all the area projected by the top plate onto the bottom plate but also leave a preferably uniform gap between its perimeter and the bottom plate's perimeter so that the capacitance field lines go from the top plate's top surface outwards into the tire tread block and back down into the bottom plate's top surface.

5. A vehicle tire tread wear sensing device according to claim 1 comprising at least two capacitor-forming plates and such that once embedded inside the tire the tread level sensing is achieved mostly through measurement of the capacitance (and/or variation thereof) between said two conductive plates (275, 276) horizontally aligned with each other and aligned vertically with (i.e. at least mostly below) the portion of tire tread (261) such sensor monitors and with the insulator layer between (278) and below (279) such plates having a permittivity such that the capacitive field lines (281, 282) go/direct mostly upwards/outwards into/through the tire tread block above the sensor rather than horizontally through said insulator layer or being affected by the tire's metal plies under the sensor.

6. A vehicle tire tread wear sensing device according to claim 1 comprising at least two capacitor-forming plates and such that once embedded inside the tire the tread depth/height/level affects the capacitance between said two conductive plates (275, 276) horizontally aligned with each other and vertically aligned with (i.e. at least mostly below) the portion of tire tread (261) such sensor monitors and with the insulator layer between (278) and below (279) such plates having a permittivity such that the capacitive field lines (281, 282) go/direct mostly upwards/outwards into/through the tire tread block above the sensor rather than horizontally through said insulator layer or being affected by the tire's metal plies under the sensor.

7. A vehicle tire tread wear sensing device according to claims 3 and 6 assembled into a tire and where a volume (309) of rubber of the tire tread said sensing device monitors is removed or molded during the tire tread forming stage and replaced/filled with a different material/compound (311) with permittivity and/or other characteristics different from those of the tire rubber so to affect the behaviour of said sensor in response to the tread wear usually in order to increase its sensitivity and/or control/direct the electric field lines formed by the capacitive plates more precisely into the tire tread block

8. A vehicle tire tread wear sensing device according to claim 1 comprising at least one coil and such that once embedded inside the tire the tread depth/height/level sensing is achieved mostly through measurement of the inductance (and variation thereof) of a said coil (291) embedded in the tire positioned preferably but not necessarily above the tire plies and below the tire tread that such sensor monitors and where above such coil inside the tread block to monitor is inserted/present a material/compound (298, 301, 311) different from the tire rubber and such that it affects the coil's inductance and/or properties and/or behaviour and/or response so to increase the coil sensitivity - when compared to rubber - to the volume/amount (and variation thereof) of the material (298, 301) present at any given time above said coil and in different so that as the tread block wears such material is also consumed/worn-off (301) resulting in different inductance values of the coil and/or in different characteristics/behaviour of the coil which the electronics the sensor/coil is connected to can detect and correlate to the tread level/depth/height.

9. A vehicle tire tread wear sensing device according to claim 1 comprising at least one coil and such that once embedded inside the tire the amount of tread depth/height/level (and variation thereof) affects the inductance of the coil (291) embedded in the tire positioned preferably but not necessarily above the tire plies and below the tire tread that such sensor monitors and where above such coil inside the tread block to monitor is inserted/present a material/compound different from the tire rubber and such that it affects the coil's inductance and/or properties and/or behaviour and/or response so to generally increase the coil sensitivity - when compared to rubber - to the volume/amount (and variation thereof) of the material present at any given time above said coil so that as the tread block wears such material is also consumed/worn-off resulting in different inductance values of the coil and/or in different characteristics/behaviour of the coil which the electronics the sensor/coil is connected to can detect and correlate to the tread level/depth/height.

10. A vehicle tire tread wear sensing device according to claims 8 and 9 assembled into a tire and where a volume of rubber said sensing device monitors is removed or a hole/voidvolume accessible from the tire's outside is pre molded in said tread and where such void/hole/volume is then replaced/filled with a different material/compound with magnetic and/or other characteristics different from those of the tire rubber so to affect the behaviour/sensitivity/performance/response/characteristics of said sensor as result of tread wear usually in order to increase senor sensitivity to tread wear and/or control/direct the magnetic field lines formed by the coil more precisely into the tire tread block.

11. A vehicle tire tread wear sensing device according to claims 1 to 10 which in order to connect to external electronics said device has conductive pads/contacts (25, 250, 256, 289, 290, 25) which once the sensor is embedded inside the tire rubber they are positioned in such a way that in order to provide electrical connectivity they are or can be exposed to the outside of the tire through holes in the tire rubber layers (6) above such pads/contacts (13, 26).

12. A vehicle tire tread wear sensing device according to claims 1 to 10 which in order to connect to external electronics said device has conductive means such as wires/conductors/foils (36, 37) which protrude (43) through the tire rubber (44) itself which is overmolded over said wires/foils so as to provide an air-tight seal. Said exposed wire/foil/conductor can then make contact with the contact/conductive-surface (54) of a substrate/flexi-strip (53)

13. A vehicle tire tread wear sensing device according to claims 1 to 10 which in order to connect to external electronics has conductive pads/plates (85, 271, 272) which once the sensor is embedded inside the tire rubber they are positioned in such a way that once the tire is assembled onto the wheel each of said pads/plates form a capacitor (Figures 28 to 32 and Fig 35 and 36) together with matching pads/plates (91, 92), positioned and aligned just below said first set of pads/plates, part of a strip/flexi-strip/substrate (88, 91) attached to and electrically isolated from the wheel and where the dielectric of said capacitor structure is provided by the tire rubber (189) compressed between the pads/plates pairs forming the capacitive coupling.

14. A vehicle tire tread wear sensing device according to claims 1 to 10 embedded inside a tire and where said tire is mounted onto a wheel onto which a flexi-strip/substrate (91, 88) with embedded capacitive plates (92, 91) matching those (82, 271, 272) of the sensor mounted inside the tire/tire-sensor and aligned so that there is capacitive coupling and a closed electrical circuit ideally comprising some controlling/monitoring electronics is formed for purposes of communication and/or sensing and/or electrical interaction between said electronics and the sensing device.

15. A vehicle tire tread wear sensing device installed inside a tire according to claims 8 to 10 and interfaced/connected to external electronics/devices through capacitive coupled connectivity means (figures 28 to 32 and Fig 35 and 36) according to claiml3 and 14 so to form a circuit which is mostly inductive (sensor) and capacitive (capacitive coupling connection to the electronics) so that the electronics can apply a signal to detect the circuit frequency response which in turn is/can-be be correlated to the tread level/depth/height.

16. A vehicle tire tread wear sensing device according to claims 1 to 9 installed inside a tire where the capacitance is measured by electronics through any of the many means possible.

17. Any of the above claims 1 to 16 where the electronics is housed inside the TPMS sensor present on a wheel or on a separate enclosed unit and whereby connectivity between such electronic, whether inside the TPMS sensor enclosure or a separate enclosure, is connected to the tire-embedded sensor/s electrically (i.e. via direct conductor contacts) and/or in a capacitively coupled via a connective flexi-strip/substrate as per claims 13 and 14

18. A number of same or different types/configuration of sensors according to claims 1 to 16 on assembled in the same or separate units/assemblies and connected to each other and/or to electronics in any combination of series and/or parallel connectivity so to monitor different areas of the tire tread.

19. Systems and devices according to claims 1 to 18 whereby the electronics can/does connect to the vehicle (wireless or wired) network, preferably the same network used by the TPMS, so to, amongst other functions, inform the driver of the tire tread level/condition.