Apparatus and method for real-time tire wear measurement

Abstract

The present invention discloses a device (1) for measuring tire wear. The device (1) comprises an ultrasonic emitter (2) and an ultrasonic receiver (3) such that the distance between the inner surface (10i) and the rolling surface (SR) of the outer surface (10e) is obtained by the emission of ultrasonic waves by the emitter (2) through the material of the tire (10) and the reception of said waves after reflection against the rolling surface (SR) by the receiver (3). The frequency of the ultrasonic waves is between 100 kHz and 500 kHz. The present invention further discloses a tire comprising said device (1) and a method for measuring tire wear using said device (1).

Description

Detailed Description of the Invention

[0001] [Subject of the invention] The present invention is in the field of tire condition monitoring in the automotive industry.

[0002] A first object of the present invention is a device designed to measure tire wear in real time.

[0003] A second object of the invention is a method that said device can implement to measure tire wear in real time.

[0004] [Prior Art] Modern automobiles are equipped with more and more sensors to measure relevant parameters for accurate driving. The information provided by these sensors is indicated to the driver by a control interface provided in the cab, for example by a light indicator or a sound alarm. The driver can take necessary measures depending on the data provided by the sensors. Alternatively, the sensor information can be transmitted to a remote location, for example a control center controlling a fleet of vehicles, to better manage maintenance operations.

[0005] In this context, TPMS (Tyre Pressure Monitoring System) has been widely known for several years. The main elements constituting a TPMS are pressure and temperature sensors connected by processing means with communication capabilities. The communication means can in principle be of any kind, providing that they transmit the information obtained by the sensors in a secure and reliable way. For example, radio frequency or, more recently, IoT technologies are commonly adopted for this purpose. These elements are integrated on an electronic board and constitute a single small component that is installed inside the tire or in the air valve of the tire of the vehicle. This arrangement allows the sensor to obtain the tire pressure and temperature in real time and to send the information to the outside for analysis. For example, the information on pressure and temperature can be sent to a control means of the vehicle, which then sends the data to the driver through the vehicle's control panel (for example, an indicator can be lit in case of an abnormality in pressure or temperature). Alternatively, the pressure and temperature information can be sent to a remote location, for example to the cloud, for analysis in a remote control center.

[0006] TPMS systems are very useful because they provide real-time information about the pressure and temperature of each tire, allowing the driver or fleet manager to take the necessary decisions to keep the tires in good condition. However, TPMS systems have the disadvantage that they do not measure perhaps the most important tire parameter: tread depth.

[0007] In fact, it is well known that many road accidents today are caused by using worn tires without replacing them in a timely manner. When tires wear out, they lose tread, reduce grip, and significantly increase the probability of accidents, especially in bad weather conditions. However, today, monitoring the condition of vehicle tires usually requires a human driver to visually inspect the tires periodically. Most vehicles with worn tires are the result of driver oversight or carelessness. Moreover, in the case of large vehicles with two tires on each side, it is almost impossible to accurately inspect the rear tire on the inner axle.

[0008] There are several known devices for measuring the tread depth of vehicle tires, however these devices either perform the measurement indirectly and the information is based on mathematical algorithms or are located outside the vehicle itself, for example, systems are known that have optical lasers mounted on the ground to measure the tread depth as the vehicle passes over them.

[0009] In conclusion, there remains a need in the art for a device that is integrated into a vehicle and that can directly and automatically provide information regarding the condition of a tire tread.

[0010] Document EP 3572245 A1 discloses a tire sensor in the form of an ultrasonic device (1) arranged on the inner side (11) of the tire opposite the tread strip (9). The ultrasonic device (1) sends a multitude of ultrasonic waves (5) in the direction of the tread blocks (4) of the tread (9). By measuring the travel time (travel time) of the ultrasonic waves (6) reflected at the interface between the surrounding air and the surface (7) of the tread blocks (4), the tread depth (15) of the vehicle tire is determined.

[0011] Document DE102015117024A1 discloses an apparatus, a tire pressure measurement system, a tire, a method and a computer program for obtaining information indicative of the tread depth of a tire. The apparatus for obtaining information indicative of the tread depth of a tire of a vehicle comprises a transducer for providing an acoustic signal based on an electrical signal and vice versa.

[0012] Description of the Invention The present invention overcomes the above-mentioned drawbacks by a device and method specifically designed to measure tire wear in real time. To this end, an ultrasonic emission / reception system is provided that is adapted to be attached to the inner surface of the tire. Moreover, similar to tire pressure and temperature information provided by conventional TPMS, the device of the present invention can transmit wear information to a vehicle control means or a remote location for proper management of tire wear. In fact, when the device of the present invention further comprises a pressure sensor and a temperature sensor, it is in effect an improved TPMS with respect to conventional TPMS.

[0013] Importantly, the apparatus of the present invention is both autonomous and automatic, i.e., autonomous in the sense that it is programmable to perform tire wear measurements without specific command, and automatic in the sense that the apparatus does not require manipulation of the tire or sensors in order to perform the measurements.

[0014] The device of the invention, a tire equipped with the device of the invention, and a method for measuring tire wear using the device of the invention will now be disclosed in more detail.

[0015] (Tire wear measuring device) A first aspect of the invention relates to a device for measuring tire wear in real time. As mentioned above, the tire has an inner surface and an outer surface, the outer surface including a tread formed by a number of grooves recessed with respect to the rolling surface of the tire. Now, the device of the invention is advantageous in that it comprises an ultrasonic emitter and an ultrasonic receiver, the emitting end of the ultrasonic emitter and the receiving end of the ultrasonic receiver being arranged to be mounted on the inner surface of the tire in a position facing (towards) a part of the rolling surface that is free of recesses. The distance between the inner surface and the rolling surface of the outer surface is obtained by emitting ultrasonic waves that pass through the material of the tire by the emitter and receiving said waves after reflection by the rolling surface by the receiver. This distance is not directly equal to the tread depth, but the tread depth can be obtained directly and simply by subtracting the obtained distance from the distance between the bottom of the groove and the inner surface of the tire.

[0016] This arrangement is advantageous because it provides an automated tire wear reading that can alert the driver or vehicle owner if tread wear is excessive.

[0017] In principle, the ultrasound may be of any frequency, provided that it can adequately pass through the tire material from the inner surface to the outer surface. In particular, devices are known for measuring the thickness of rubber, based on the emission of ultrasound at frequencies of several gigahertz, for example 2 MHz to 3 MHz. However, the inventors of the present application have experimentally found that these frequencies are not suitable for measuring the thickness of tires, due to the fact that the tires have a reinforcing metal mesh that prevents the passage of ultrasound. Indeed, at the aforementioned frequencies, the ultrasound cannot pass through the metal mesh, but instead hits it and is reflected. To solve this problem, the inventors of the present application have found that the frequency of the ultrasound should be lower, between 100 KHz and 500 KHz, with the best results being obtained at 200 KHz to 300 KHz. Thus, according to a particularly preferred embodiment of the present invention, the ultrasound emitter and the ultrasound receiver are configured to emit and receive, respectively, ultrasound at frequencies between 100 KHz and 500 KHz, more preferably between 200 KHz and 300 KHz.

[0018] As mentioned above, this configuration is advantageous as it allows the device of the present invention to be employed in tires having reinforcing metal mesh.

[0019] Although the emitter and receiver can have several different configurations, according to one particularly preferred embodiment of the invention, the emitting end of the ultrasonic emitter and the receiving end of the ultrasonic receiver are arranged on a mounting surface of the device to the tire. The mounting surface of the device is the surface on which the device of the invention is mounted to the tire, and its shape can be adapted to the curvature of the inner side of the tire. Furthermore, the mounting surface may include a mounting means such as a chemical adhesive, so that when the device of the invention is mounted to the inner surface of the tire, the emitting end of the emitter and the receiving end of the receiver are in direct contact with said inner surface of the tire, such that the ultrasonic waves emitted by the emitter are directly incident on the tire material.

[0020] This configuration is advantageous in that the measurement results are more accurate since the ultrasound does not have to pass through the air / tire material interface.

[0021] On the one hand, the emitter and the receiver may be located anywhere in the device, provided that the signal transmitted by the emitter can be correctly received by the receiver, however, according to a particularly preferred embodiment of the invention, the ultrasound emitter and the ultrasound receiver are adjacent to each other.

[0022] This configuration is advantageous in that it increases the accuracy of the measurement and also results in a particularly compact device.

[0023] Preferably, the device of the present invention further includes a pressure sensor and a temperature sensor. These sensors may be of any type and may be located anywhere in the device as long as they obtain the temperature and pressure inside the tire. For example, pressure sensors and temperature sensors similar to those used in conventional TPMS may be employed.

[0024] This arrangement has the advantage that complete information about the condition of the tire (including pressure, temperature, and wear level) is obtained, which is sufficient to determine when the tire requires maintenance or replacement.

[0025] According to yet another preferred embodiment, the device of the invention further comprises communication means, which may be of any type, allowing the transmission of information about the wear of the tire and, if necessary, the temperature and pressure inside the tire to the control means of the vehicle or to a remote location. By way of example only, the communication means may be based on IoT technologies, including Bluetooth, Wifi, Zigbee, NFC, UMTS, GPRS, GSM, 3G, 4G, 5G communication technologies, or any other suitable technology for establishing the abovementioned communication.

[0026] (Tire with the device disclosed above) The invention further relates to a tire comprising a device as disclosed in the above paragraph, in which said device is attached by its mounting surface to the inner side of the tire in a position facing the portion of the rolling surface that does not have grooves. A tire of this type may be readily mounted on a vehicle and used as an intelligent tire.

[0027] (Method for measuring tire wear) The present invention further discloses a method for measuring tire wear in real time using the device disclosed in the previous paragraph. Of course, before carrying out the method, the device must be mounted on the inner surface of the tire in a position facing the portion of the rolling surface that does not have grooves. The method comprises the following steps: 1. Emitting ultrasonic waves through the tire material by an ultrasonic emitter, the emission direction being substantially perpendicular to the inner surface of the tire, which minimizes the travel distance of the ultrasonic waves through the tire material and requires simpler calculations. 2. Receiving the ultrasonic waves after reflection on the rolling surface by an ultrasonic receiver. 3. Measuring the distance between the inner and outer rolling surfaces based on the time of flight of the ultrasonic waves and the propagation speed of the ultrasonic waves through the tire material, said distance measurement being performed by calculations commonly known in the art.

[0028] According to the above, the result of this method does not immediately correspond to the most adopted parameter for measuring the wear of vehicle tires, namely the tread depth. However, from the information provided by the device, the tread depth can be determined in several ways. For example, the current tread depth can be determined by simply subtracting the wear from the initial tread depth (obtained, for example, by subtracting the initial depth of the tire from the actual depth at a certain moment). Alternatively, it would be possible to use two devices of the type disclosed above, one of them placed at a position on the inner surface facing the part of the rolling surface without grooves and the other at a position on the inner surface facing the bottom of the grooves. The difference in the distances obtained by both devices is directly the tread depth.

[0029] In any event, the apparatus of the present invention can periodically perform this method to determine the condition of the tires in real time. Furthermore, by obtaining this information in real time, tire wear rates can be analyzed in response to weather or other factors related to driving style, providing patterns that can help drivers extend the useful life of their vehicles.

[0030] According to one particularly preferred embodiment of the invention, the ultrasound has a frequency between 100 KHz and 500 KHz, more preferably between 200 KHz and 300 KHz. As mentioned above, this frequency range ensures that the ultrasound passes through, for example, metal meshes that are included as reinforcement in many tires.

[0031] Finally, according to yet another preferred embodiment, the ultrasonic waves are emitted substantially perpendicular to the inner surface of the tire, which minimizes the distance the waves travel and provides more accurate results.

[0032] (Procedure for initial calibration of the device) Due to the variety of structures and materials used to make tires, the sound propagation speed varies from one tire model to another. Therefore, it is necessary to measure the speed at which sound propagates through the tire on which the device is placed. Furthermore, in order to measure the tread depth at any given moment with the device of the present invention, it is necessary to know the initial depth of the grooves that make up said tread, from which the wear amount obtained with the device of the present invention can be subtracted to finally obtain the groove depth in real time.

[0033] In this regard, the method for initial calibration of the device includes measuring these two variables, namely the sound propagation velocity and the initial tread depth, and then transmitting both to a tire wear measurement system, which then calibrates the device for the particular tire model on which it is installed.

[0034] There are several ways to determine these two variables, but according to one particular embodiment of the invention, the sound propagation speed is preferably measured by connecting a sound speed sensor between the outer and inner surfaces of the tire, while the initial tread depth is preferably measured using a caliper to measure the depth of the grooves that make up the tire's tread.

[0035] By performing these steps for each tire model, a database is generated to accurately calibrate the device of the present invention to the tire model being installed. This database could be associated with an app that allows the installer to easily and quickly retrieve data for each tire model.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a schematic diagram of the main components of an exemplary apparatus according to the present invention.

[0037] FIG. 2 shows an exemplary device according to the present invention mounted on the inside surface of a tire.

[0038] FIG. 3 shows another exemplary device according to the present invention secured to the inner surface of a tire.

[0039] [Preferred embodiment of the present invention] Figure 1 shows a schematic diagram of a device (1) according to the invention. As shown, the device (1) comprises a processing means (8) connected to an ultrasonic emitter / receiver (2, 3), a pressure sensor (4), a temperature sensor (5), a communication means (6) and a battery (7).

[0040] The processing means (8) may be of any type capable of appropriately controlling other elements in the manner disclosed herein, for example, the processing means may be a microcontroller, a microprocessor, a System on Chip (SoC), an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), or any other similar component with a suitable number of input / output ports and sufficient computing power.

[0041] The emitter / receiver (2, 3) in this embodiment is shown as a single element, since components incorporating both elements for measuring distances using the method disclosed herein are known in the field of distance measurement. However, the emitter / receiver (2, 3) could be implemented in various ways, in particular by two separate elements appropriately arranged. In particular, the emitting end of the emitter (2) and the receiving end of the receiver (3) are arranged flush in the face of the device (1) adapted to be mounted on the inner surface (10i) of the tire (10), as shown in FIG. 2.

[0042] The pressure sensor (4) and the temperature sensor (5) may be similar to those conventionally employed in known TPMS, their function being to provide measurements of the pressure and temperature inside the tire.

[0043] The communication means (6) may be of any type allowing communication between the device (1) mounted inside the tire (10) in use and a remote location, such as a control means of a vehicle or a control centre of a fleet of vehicles. The communication means (6) are therefore based on a technology suitable for the respective application, including for example IoT technologies, Bluetooth, Wifi, Zigbee, NFC, UMTS, GPRS, GSM, 3G, 4G, 5G, etc. It should be noted that, depending on the type of processing means (8) employed, the communication means (6) may be integrated into the processing means (8) itself. In this context, it is irrelevant whether both elements are integrated into a single component or whether they constitute separate components.

[0044] The battery (7) may be of any type capable of providing sufficient energy to the device (1) throughout its useful life.

[0045] FIG. 2 shows the device (1) of the present invention fixed to the inner surface (10i) of a tire (10). As shown, the device (1) of the present invention has a mounting surface on which the emitting end of the emitter (2) and the receiving end of the receiver (3) are located. That is, both ends are flush with a substantially flat surface configured to be attached to the inner surface (10i) of the tire (10), for example by adhesive. Of course, to prevent the adhesive from affecting the ultrasound, the mounting surface has an emitting / receiving portion on which the emitting and receiving ends of the emitter (2) and receiver (3) are located, and a mounting portion (not shown) separate from the above-disclosed portion, in which adhesive is provided for attaching the device (1) to the tire (10).

[0046] The emitter (2) transmits ultrasonic waves substantially perpendicular to the inner surface (10i) of the tire (10). The waves pass through the material that constitutes the tire (10), are reflected at the interface with air that is constituted by the rolling surface (SR) and return again to a receiver (3) placed next to the emitter (2). The device (1) determines the time of flight of the ultrasonic waves. Knowing the speed of propagation of the ultrasonic waves in the material that constitutes the tire, the distance traveled can then be easily measured in known manner. The current thickness (G) of the tire (10), i.e. the distance between the inner surface (10i) and the rolling surface (SR) of the outer surface (10e), is half the distance traveled by the ultrasonic waves.

[0047] Once the current thickness (G) is known, there are various ways to determine the depth (PS) of the grooves (S) constituting the tread on the outer surface (10e) of the tire (10). For example, once the initial thickness (G0) of the tire (10) is known, the amount of wear of the tire (10) can be measured at any time by subtracting (G0)-(G). For example, the initial thickness (G0) can be obtained by performing a first measurement of the thickness of the tire (10) before the tire (10) is used for the first time or at the moment when the tire (10) is used for the first time. The depth of the groove (PS) at any given moment is the initial depth of the groove (PS0), known for each tire model, minus the amount of wear calculated by the device (1) of the invention. That is, PS=PS0-[(G0)-(G)] Alternatively, two devices (1) such as those disclosed herein can be used. The first device (1) can be placed in the position shown in Figure 2 to determine the current thickness (G) at any given moment. The second device (1) is placed in a position on the inner surface (10i) facing the groove (S). As a result, the transmitted ultrasound is reflected at the bottom of the groove (S), thereby obtaining the distance between the inner surface (10i) and the bottom of the groove (S), which is referred to herein as FS. With this configuration, the current groove depth (PS) at any given moment is obtained by subtracting the total thickness (G) from said distance (FS): PS=G-FS In any case, it is easy to see that the device (1) of the present invention provides information that allows the amount of tire wear to be determined by simple calculations.

[0048] Figure 3 shows another schematic diagram of an exemplary device (1) according to the invention. In this figure, pressure and temperature sensors are not shown. However, it is understood that the device of Figure 3 is integrated into a TPMS having three different sensors: thickness, temperature and pressure. These sensors are housed in the same cover, but use different control systems.

[0049] To use the device, the sound propagation speed and the initial tread depth for this particular tire model must be known. The installer first searches for this tire model in a list accessible from the app. If data corresponding to that particular tire model is available, they are introduced into the device of the invention so that it can be used. If not, the installer must measure both variables. A sound speed sensor (100) connected between the outer and inner surfaces of the tire is used to measure the sound propagation speed, and a caliper is used to measure the initial depth of the tread grooves of the tire. Once the data are obtained, the installer introduces them into the device of the invention and also saves them in the app's list for future use.

[0050] The TPMS thus configured continuously monitors the tire pressure, temperature and tread depth throughout the entire service life of the tire. For this purpose, the pressure and temperature sensors measure the pressure and temperature every hour and transmit them to the vehicle's control means. The tire wear measurement must be performed when the tire is cold, i.e. when the vehicle has been parked for a certain time. Therefore, the TPMS has an acceleration sensor that measures the acceleration of the vehicle in parallel with the pressure and temperature measurement. If it is detected that the vehicle is parked, the TPMS waits for 10 minutes and measures the acceleration again. After another 10 minutes, the same measurement is performed a third time. If after these three consecutive measurements the vehicle is still parked and 24 hours have passed since the last measurement, the TPMS commands the tire wear measurement device to perform a measurement and transmit the result of the measurement to the vehicle's control means. [Brief description of the drawings]

[0051] [Figure 1] 1 shows a schematic diagram of the main components of an exemplary apparatus according to the present invention. [Diagram 2] 1 shows an exemplary device according to the present invention mounted on the inside surface of a tire. [Diagram 3] 3 illustrates another exemplary device according to the present invention secured to the inner surface of a tire.

Claims

1. A device (1) for real-time tire wear measurement for a tire (10) having an inner surface (10i) and an outer surface (10e), comprising: The outer surface (10e) includes a tread formed by a plurality of grooves (S) recessed relative to the rolling surface (SR); The device (1) comprises an ultrasonic emitter (2) and an ultrasonic receiver (3), said device (1) being adapted to be attached to said inner surface (10i) of said tire (10) in such a way that distance is obtained by emission of ultrasonic waves by said emitter (2) through the material of said tire (10) and reception by said receiver (3) of said waves after reflection from said rolling surface (SR); The apparatus (1), wherein the ultrasonic emitter (2) and the ultrasonic receiver (3) are configured to emit and receive ultrasonic waves at a frequency between 100 KHz and 500 KHz, respectively.

2. The device (1) according to claim 1, wherein the ultrasonic emitter (2) and the ultrasonic receiver (3) are configured to emit and receive ultrasonic waves at a frequency between 200 KHz and 300 KHz, respectively.

3. 3. The device (1) according to claim 1 or 2, wherein the emitting end of the ultrasonic emitter (2) and the receiving end of the ultrasonic receiver (3) are arranged on a mounting surface of the device to the tire (10).

4. The device (1) according to any one of claims 1 to 3, wherein the ultrasonic emitter (2) and the ultrasonic receiver (3) are adjacent to each other.

5. The device (1) according to any one of the preceding claims, further comprising a pressure sensor (4) and a temperature sensor (5).

6. The device (1) according to any one of the preceding claims, further comprising communication means (6).

7. A tire system (10) comprising a device (1) according to any one of claims 1 to 6, The device (1) is attached to the inner surface (10i) of the tire (10) via its mounting surface in a position where the emitting end of the ultrasonic emitter (2) and the receiving end of the ultrasonic receiver (3) face a portion of the rolling surface (SR) without grooves (S) so that the distance between the inner surface (10i) and the rolling surface (SR) of the outer surface (10e) is obtained by the emission of ultrasonic waves by the emitter (2) through the material of the tire (10) and the reception of the waves by the receiver (3) after reflection at the rolling surface (SR) of the tire (10).

8. A method for real-time tire wear measurement by means of a device (1) according to any one of claims 1 to 6, comprising: the device (1) is attached to the inner surface (10i) of the tire (10) in a position facing a portion of the rolling surface (SR) that is free of grooves (S); The method comprises: - emitting, by means of said ultrasonic emitter (2), ultrasonic waves passing through the material of said tire (10); - receiving, by said ultrasonic receiver (3), said ultrasonic waves after reflection from said rolling surface (SR); - measuring the distance between said inner surface (10i) and said rolling surface (SR) of said outer surface (10e) from the time of flight of said ultrasound waves and their propagation speed through the material of said tire (10); Including, The method of claim 1, wherein the ultrasound has a frequency between 100 KHz and 500 KHz.

9. The method of claim 8, wherein the ultrasound has a frequency between 200 KHz and 300 KHz.

10. 10. The method according to claim 8 or 9, wherein the ultrasonic waves are emitted substantially perpendicular to the inner surface (10i) of the tire (10).

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