Tire wear measuring device and power generation device

Abstract

A tire wear measuring device (10) of the present invention that detects wear of a tire (20) based on a magnetic field of a magnetic body (30) embedded in the tire (20) is provided with a magnetic sensor (12A, 12B) and a battery (11), the battery (11) is capable of transmitting the magnetic field of the magnetic body (30), and from an outer peripheral end (11e) thereof, the magnetic field of the magnetic body (30) is discharged as a discharge magnetic field, the magnetic sensor (12A, 12B) is disposed at a position capable of detecting the discharge magnetic field, thus, wear of the tire can be detected with high precision, and is suitable for small size and light weight.

Description

Technical Field

[0001] This invention relates to a tire wear measuring device and a power generation device that detects tire wear based on the magnetic field of a magnet embedded in the tire. Background Technology

[0002] If tire wear accelerates, its grip on the road surface decreases, as does its water drainage performance when driving on wet surfaces. Therefore, drivers and vehicle managers visually inspect the tire tread wear to ensure safety and replace tires before they exceed their wear limit. Visual inspections utilize tread wear indicators located in the tire grooves. However, this process is complex, and there is a risk of misjudging the wear condition. It is also considered that inspections may not be performed depending on the user. Continuing to use tires with degraded performance due to misjudgment is not preferable from a safety perspective.

[0003] Therefore, a sensor module for determining the degree of tire wear by methods other than visual inspection has been proposed. For example, Patent Document 1 describes a sensor module configured to have a magnetic sensor that detects the magnetic flux density of a magnetic field in the radial direction of the tire tread, and to determine the wear of the tire tread based on the magnetic flux density detected by the magnetic sensor.

[0004] Furthermore, Patent Document 2 discloses a tire-in-tire power generation device, which has a magnet arranged in an oscillator for supplying power to a device inside the tire, and a coil arranged on the main body supporting the oscillator. The magnet rotates and generates electricity while the tire rotates.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-203831

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-239510 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the purpose of the sensor module described in Patent Document 1 is to measure the strength of the magnetic field that changes due to wear, and to accurately monitor the wear condition of the tire at all times. Therefore, this document does not describe a small and lightweight configuration for the sensor module. Furthermore, since the sensor module is installed on the tire for use, if it is large or heavy, it may cause a loss of balance when the tire rotates. Therefore, it is also required that the sensor module be as small and lightweight as possible. In addition, the device described in Patent Document 2 is a large-scale power generation system, so its weight is likely to increase, and the possibility of a loss of balance when the tire with this device installed is also taken into consideration.

[0011] The purpose of this invention is to provide a tire wear measuring device that can detect tire wear with high precision, suitable for small and lightweight applications, and a power generation device that can be installed inside the tire.

[0012] Methods for solving problems

[0013] The present invention provides a tire wear measuring device comprising a magnetic sensor and a magnetic collecting component, which detects tire wear based on the magnetic field of a magnet embedded in the tire. The magnetic collecting component is characterized in that it can transmit the magnetic field of the magnet and release the magnetic field of the magnet as an emitted magnetic field from its outer peripheral end, and the magnetic sensor is disposed at a position capable of detecting the emitted magnetic field.

[0014] Based on the above configuration, by detecting the emitted magnetic field from the magnetic collecting component, it is not necessary to place the magnetic sensor near the magnet embedded in the tire. Therefore, the design of the magnetic sensor becomes more flexible, simplifying the construction of the tire wear measuring device to achieve miniaturization and lightweight design, while also ensuring good detection accuracy.

[0015] Preferably, the tire wear measuring device includes a magnetic field sensing component that senses the emitted magnetic field. In this case, it is preferable that the magnetic collecting component is a coin-shaped battery, and when viewed from above in the direction normal to the electrode surface of the coin-shaped battery, the end of the magnetic field sensing component on the magnetic sensor side is disposed outside the outer periphery of the coin-shaped battery, and the magnetic sensor is disposed between the coin-shaped battery and the end of the magnetic field sensing component.

[0016] Based on the above configuration, the emitted magnetic field sensed by the magnetic field sensing component can be effectively detected by the magnetic sensor, thus improving the detection accuracy of the magnetic sensor. Specifically, an emitted magnetic field sensed by the magnetic field sensing component is formed between the coin-shaped battery and the end of the magnetic field sensing component. By sensing the emitted magnetic field through the magnetic field sensing component, the magnetic flux density can be increased. Therefore, by arranging the magnetic sensor between the coin-shaped battery and the end of the magnetic field sensing component, the magnetic sensor can detect the emitted magnetic field with high accuracy.

[0017] Preferably, the coin-shaped battery is arranged with its electrode surfaces facing the magnet. With this configuration, the emitted magnetic field is emitted entirely from the outer periphery of the coin-shaped battery; therefore, by placing a magnetic sensor near the outer periphery, the emitted magnetic field can be detected.

[0018] Alternatively, the aforementioned magnetic field sensing component can be used as an antenna that radiates and receives electromagnetic waves, acting as a waveguide. By using a communication antenna as the magnetic field sensing component, the tire wear measuring device can be made smaller and lighter.

[0019] Alternatively, the detectable direction of the magnetic sensor may be parallel to the electrode surface of the coin-shaped battery, and the end of the magnetic field sensing component and the magnetic sensor may be arranged on the same plane parallel to the electrode surface of the coin-shaped battery.

[0020] According to this configuration, the emitted magnetic field detected by the magnetic sensor contains more components parallel to the electrode surface of the coin-shaped battery, thus enabling effective detection of the emitted magnetic field.

[0021] Alternatively, the magnetic sensor may have a first sensor and a second sensor. The first sensor is disposed on one side and the second sensor is disposed on the other side, in a direction parallel to the electrode surface of the coin-shaped battery, with the coin-shaped battery in between. Tire wear is detected based on the output of the first sensor and the output of the second sensor.

[0022] In this case, preferably, when viewed from above in the normal direction of the electrode surface of the coin-shaped battery, the center of the electrode surface of the coin-shaped battery overlaps with the magnet embedded in the tire and is located on the straight line connecting the first sensor and the second sensor.

[0023] By using the outputs of both the first and second sensors, the effects of noise such as external magnetic fields can be eliminated. Furthermore, the magnetic field is oriented in opposite directions on one side and the other side, separated by a coin-shaped battery. Therefore, for example, by using the output difference between the two sensors, approximately twice the output can be obtained compared to the output of a single magnetic sensor, thus improving detection accuracy.

[0024] Alternatively, when the tire wear measuring device is equipped with a magnetic field sensing component that senses the emitted magnetic field, the magnetic sensor has a first sensor and a second sensor, the magnetic field sensing component has a first end and a second end as the ends of the magnetic sensor side, the magnetic collecting component is a coin-type battery, and the first sensor and the first end are arranged on one side, separated from the coin-type battery, in a direction parallel to the electrode surface of the coin-type battery, and the second sensor and the second end are arranged on the other side, and the tire wear is detected based on the output of the first sensor and the output of the second sensor.

[0025] The magnetic sensor can effectively detect the emitted magnetic field sensed by the magnetic field sensing component, thus improving the accuracy of tire wear measurement.

[0026] Alternatively, the tire wear measuring device may include a coil positioned within the magnetic field range of the magnet, enabling the use of the induced current generated by the coil as an operating power source. In this case, it is preferable that the coil is positioned between the magnetizing component and the magnet.

[0027] The magnetic flux density of the coil changes as the relative position of the magnet and the coil changes with the rotation of the tire. By placing the coil between the magnetizing component and the magnet, the magnetic flux density through the coil increases, thus improving power generation efficiency. Therefore, the electricity generated by the coil can be used for the operation of the tire wear measuring device while maintaining a small size.

[0028] This invention provides a power generation device comprising a magnet embedded in a tire and a coil disposed within the magnetic field range of the magnet. The relative position of the magnet and the coil changes as the tire rotates, and power is generated by utilizing the change in magnetic flux density through the coil caused by the change in the relative position. Preferably, the power generation device includes a magnetic component, and the coil is disposed between the magnetic component and the magnet.

[0029] Based on the above configuration, it is possible to generate electricity using the induced current generated by the change in magnetic flux density of the coil that accompanies the rotation of the tire.

[0030] Invention Effects

[0031] The tire wear measuring device of the present invention detects the emitted magnetic field from the magnetic collecting component, thereby increasing the degree of freedom in the configuration of the magnetic sensor, enabling miniaturization, lightweight design, and high-precision measurement of tire wear. Furthermore, by configuring a coil, the device does not become large-scale, and it is possible to generate electricity using the induced current generated by the change in magnetic flux density of the magnetic field passing through the coil as the tire rotates. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view schematically illustrating the configuration of a tire wear measuring device according to an embodiment of the present invention.

[0033] Figure 2(a) shows Figure 1 Figure 2(b) shows the vector diagram of the magnetic field of the tire wear measuring device. Figure 1 The contour map of the magnetic field sensor of the tire wear measuring device.

[0034] Figure 3(a) shows Figure 1The contour plot of the magnetic field sensor detected by the tire wear measuring device, Figure 3(b) shows the contour plot of the magnetic field sensor detected by the device. Figure 8 The contour map of the magnetic field sensor in the tire wear measuring device.

[0035] Figure 4 It is a schematic representation Figure 1 A diagram illustrating the positional relationship between the magnet, coin-shaped battery, magnetic sensor, and antenna end in a tire wear measuring device.

[0036] Figure 5 This is a cross-sectional view schematically illustrating the configuration of a modified example of a tire wear measuring device.

[0037] Figure 6(a) shows Figure 5 Figure 6(b) shows a vector diagram of the magnetic field in the tire wear measuring device. Figure 5 The contour map of the magnetic field sensor in the tire wear measuring device.

[0038] Figure 7 It is a schematic cross-sectional view showing the tire wear measuring device installed on the tire.

[0039] Figure 8 This is a schematic cross-sectional view showing the configuration of a conventional tire wear measuring device.

[0040] Figure 9(a) shows Figure 8 Figure 9(b) shows a vector diagram of the magnetic field in the tire wear measuring device. Figure 8 The contour map of the magnetic field sensor in the tire wear measuring device.

[0041] Figure 10 This is a cross-sectional view schematically illustrating the configuration of other variations of the tire wear measuring device.

[0042] Figure 11 This is a cross-sectional view schematically illustrating the configuration of a power generation device according to an embodiment of the present invention.

[0043] Figure 12(a) is a perspective view showing the shape of the tire wear measuring device of Example 1 and Example 2, and Figure 12(b) is a perspective view showing the shape of the tire wear measuring device of Comparative Example 1.

[0044] Figure 13 This is a graph representing the output ratios of Examples 1, 2, and Comparative Example 1. Detailed Implementation

[0045] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same components are labeled with the same numbers, and descriptions are omitted where appropriate.

[0046] Figure 7 This is a schematic cross-sectional view showing the tire wear measuring device according to an embodiment of the present invention installed on a tire. As shown in the figure, the tire wear measuring device 10 is disposed on the inner side 21 of the tire 20, and a magnetic body 30 is embedded in the tread portion 23 of the outer side 22. As the magnetic body 30 wears along with the tread portion 23, the magnetic field M from the magnetic body 30 (shown by the dotted line in the figure) changes. Therefore, the tire wear measuring device 10 can detect the wear condition of the tread portion 23 by measuring the magnetic field M. For example, based on a table pre-stored with changes in the magnetic field M accompanying the wear of the magnetic body 30 and the measured value of the magnetic field M, the wear condition of the tire 20 can be determined.

[0047] Figure 8 This is a schematic cross-sectional view illustrating the configuration of a conventional tire wear measuring device. As shown in the figure, the tire wear measuring device 100 includes a coin-type battery 101. The coin-type battery 101 is encapsulated in a soft magnetic material with high magnetic permeability, thus the magnetic field generated by the magnetic body 30 embedded in the tread portion 23 of the tire 20 is easily sensed by the coin-type battery 101. Therefore, conventionally, the coin-type battery 101 is not positioned between the magnetic body 30 and the magnetic sensors 102A and 102B. The magnetic sensors 102A and 102B are positioned closer to the magnetic body 30 than the coin-type battery 101 but sufficiently far away from it. That is, the distance D1 from the magnetic body 30 to the coin-type battery 101 is greater than the distance D2 from the magnetic body 30 to the magnetic sensors 102A and 102B to avoid affecting the magnetic detection of the magnetic sensors 102A and 102B. The coin-type battery 101 and the magnetic sensors 102A and 102B are positioned as follows... Figure 8 The configuration shown is the reason why the tire wear measuring device 100 has a complex structure and a large size.

[0048] Figure 9(a) shows Figure 8 Figure 9(b) shows a vector diagram of the magnetic field in the tire wear measuring device. Figure 8 The contour plot shows the magnetic field components detected by the sensor in the tire wear measuring device. The vector diagram uses vectors to represent the direction and flux density of the magnetic field. The contour plot uses varying shades to represent the flux density of the X-axis component of the magnetic field; the greater the flux density, the darker the color.

[0049] As shown in Figure 9(a), conventional tire wear measuring devices 100 form a region of high magnetic flux density near the magnetic body 30. Therefore, magnetic sensors 102A and 102B are placed in this region to detect the magnetic flux from the magnetic body 30. However, as shown in Figure 9(b), it can be seen that a region of high magnetic flux density in the X-axis direction is formed near the outer peripheral end 101e of the coin-shaped battery 101 on the opposite side of the magnetic body 30. The magnetic field in this region is the emitted magnetic field emitted by the coin-shaped battery 101, which senses the magnetic field from the magnetic body 30, and changes with the magnetic field from the magnetic body 30. Therefore, by measuring this emitted magnetic field, changes in the magnetic field of the magnetic body 30 can be detected.

[0050] That is, by configuring the coin-shaped battery 101 near the magnetic body 30 with the magnetic sensors 102A and 102B, and configuring the magnetic sensors 102A and 102B at a position capable of detecting the emitted magnetic field emitted from the outer peripheral end 101e of the coin-shaped battery 101, changes in the magnetic field from the magnetic body 30 can be measured. According to this configuration, the coin-shaped battery 101 can be used as a magnetic collecting component (simulating a magnetic yoke), thus simplifying the structure and enabling miniaturization and weight reduction of the tire wear measuring device 100. Embodiments of the present invention will be described below.

[0051] Figure 1 This is a cross-sectional view schematically illustrating the configuration of a tire wear measuring device according to an embodiment of the present invention. As shown in the figure, the tire wear measuring device 10 of this embodiment includes magnetic sensors 12A and 12B and a coin-type battery 11, which detects the magnetic field of the magnetic body 30 embedded in the tire 20 and measures the wear of the tire 20.

[0052] The coin-type battery 11 is positioned at a location capable of transmitting the magnetic field of the magnetic body 30, and emits the magnetic field from the magnetic body 30 as an outgoing magnetic field from its outer peripheral end 11e. In this embodiment, a coin-type (button-type) battery, which is generally used as a power source for the tire wear measuring device 10, will be described. However, it is not limited to the coin-type battery 11, and a magnetic collecting component capable of transmitting the magnetic field of the magnetic body 30 can be used. Here, "magnetic collecting component capable of transmitting the magnetic field" refers to a component such as a battery that has a portion made of a soft magnetic material with high magnetic permeability and is capable of emitting the magnetic field from the magnetic body 30 as an outgoing magnetic field. The coin-type battery 11 uses a soft magnetic material in its package (outer casing) that extends from its electrode surface 11d to its outer peripheral end 11e. Therefore, by being positioned at a location affected by the magnetic field of the magnetic body 30, it can transmit the magnetic field of the magnetic body 30 and emit it as an outgoing magnetic field from its outer peripheral end 11e on the side away from the magnetic body 30.

[0053] In this embodiment, the location affected by the magnetic field of the magnetic body 30 refers to the region where the magnetic flux density from the magnetic field of the magnetic body 30 can be detected. If the magnetic flux density is not 0 mT, it can be detected, but it is easily affected by noise when the magnetic flux density is low. Therefore, it is preferable, for example, to obtain the difference between multiple detection results to cancel out the noise effect. Furthermore, the location where the magnetic field of the magnetic body 30 is located refers to the location where the portion made of the soft magnetic material that transmits the magnetic field is located. Additionally, in the coin-type battery 11, if the portion made of the soft magnetic material of the electrode surface 11d is located at the location affected by the magnetic field, the magnetic field can be transmitted and emitted from the outer peripheral end 11e. Therefore, the entire portion made of the soft magnetic material may not be located at the location affected by the magnetic field of the magnetic body 30.

[0054] The coin-shaped battery 11 is configured with its electrode surface 11d facing the magnetic body 30. That is, the electrode surface 11d is positioned opposite the inner surface 21 of the tire 20 with the direction of the normal 11L of the electrode surface 11d (normal direction) pointing towards the Y-axis. Therefore, the coin-shaped battery 11 can effectively transmit the magnetic field from the magnetic body 30 and emit it as a discharging magnetic field from its outer peripheral end 11e.

[0055] Magnetic sensors 12A and 12B are disposed on the side 11f opposite to the magnetic body 30, separated by the coin-shaped battery 11, and are capable of detecting the position of the emitted magnetic field emitted from the outer peripheral end 11e. Furthermore, magnetic sensors 12A and 12B are disposed on the same plane. Additionally, the emitted magnetic field extends from the outer peripheral end 11e towards... Figure 1 The magnetic field emitted diagonally upwards forms a region near the outer peripheral end 11e where the magnetic flux density is higher than that of the surrounding area. That is, by positioning the magnetic sensors 12A and 12B at positions capable of detecting the emitted magnetic field from the outer peripheral end 11e, changes in the magnetic field can be detected with high precision. For the magnetic sensors 12A and 12B to detect the emitted magnetic field, it is preferable, for example, that the magnetic flux density in the detectable direction at the positions of the magnetic sensors 12A and 12B is 0.4 mT or higher. Furthermore, the magnetic flux density in this embodiment refers to the magnetic flux density detected when a new tire 20 is equipped with the tire wear measuring device 10 before use.

[0056] For example, when using a magnetic body 30 that generates a magnetic field with a surface magnetic flux density of 26 mT, if a coin-shaped battery 11 is positioned at a distance D1 of approximately 10 to 20 mm from the magnetic body 30 to the electrode surface 11d, the magnetic field can be transmitted through the coin-shaped battery 11. From the viewpoint of accurately detecting the emitted magnetic field from the outer peripheral end 11e using magnetic sensors 12A and 12B, the magnetic sensors 12A and 12B are configured such that the distance (LX) in the X-axis direction from the outer peripheral end 11e of the coin-shaped battery 11 is 2.8 mm or less, preferably 2.5 mm or less, and more preferably 2.3 mm or less. Furthermore, from the same viewpoint, the magnetic sensors 12A and 12B are configured such that the distance (LY) in the Y-axis direction from the outer peripheral end 11e of the coin-shaped battery 11 is 3.2 mm or less, preferably 2.9 mm or less, and more preferably 2.7 mm or less.

[0057] like Figure 1 As shown, the distance D2 between the magnetic sensors 12A and 12B and the magnetic body 30 in the Y-axis direction is greater than the distance D1 between the coin-shaped battery 11 and the magnetic body 30. Therefore, the magnetic sensors 12A and 12B do not directly detect the magnetic field from the magnetic body 30, but rather detect the emitted magnetic field transmitted through the coin-shaped battery 11 and emitted from its outer peripheral end 11e. Furthermore, in this embodiment, the distance between components refers to the distance between the closest parts of the components.

[0058] Magnetic sensors 12A and 12B measure the emitted magnetic field from the outer peripheral end 11e using a magnetoresistive element whose resistance changes according to the direction and intensity of the magnetic field. Examples of magnetoresistive elements include GMR elements and TMR elements. The measurements by magnetic sensors 12A and 12B do not need to be performed continuously in real time; they can be performed intermittently at regular intervals. Alternatively, measurements can be performed based on instructions received from an external source via a wireless communication unit (not shown). By performing measurements at regular intervals or based on instructions, power consumption can be reduced compared to continuous measurements. Hall elements can also be used instead of magnetoresistive elements in magnetic sensors 12A and 12B to measure changes in magnetic flux intensity. Furthermore, magnetoresistance elements can be used as magnetic sensors 12A and 12B to measure changes in impedance caused by changes in the magnetic field.

[0059] Magnetic sensors 12A and 12B are configured to detect magnetic flux density in the X-axis direction, thus enabling high-precision detection of the emitted magnetic field from the outer peripheral end 11e. However, they can also be configured to detect magnetic fields not only in the X-axis direction but also in three mutually orthogonal axial directions (X-axis, Y-axis, and Z-axis). In this case, magnetic sensors 12A and 12B can be configured as three sensors with uniaxial detection. Furthermore, in this embodiment, magnetic sensors 12A and 12B are GMR sensors with GMR elements integrated within a molded package.

[0060] The tire wear measuring device 10 can also output information related to tire wear 20 based on the magnetic field measurements by magnetic sensors 12A and 12B to a vehicle-side device via a wireless communication unit. It can send the measurement results of magnetic sensors 12A and 12B to the vehicle-side device or receive information from the vehicle-side device via the wireless communication unit. The transmission and reception of information between the tire wear measuring device 10 and external devices is controlled by a CPU (not shown).

[0061] The tire wear measuring device 10 includes an antenna 13 for external communication. Its two ends 13a and 13b are respectively positioned near magnetic sensors 12A and 12B, capable of sensing the emitted magnetic field from the outer peripheral end 11e. The antenna 13 acts as a waveguide, radiating and receiving electromagnetic waves, and functions as a magnetic field sensing component (yoke) for sensing the emitted magnetic field from the outer peripheral end 11e of the coin-shaped battery 11. The ends 13a and 13b of the antenna 13 are positioned near the outer peripheral end 11e of the coin-shaped battery 11, functioning as a magnetic field sensing component (yoke) for sensing the emitted magnetic field. Magnetic sensors 12A and 12B are positioned between the outer peripheral end 11e and the ends 13a and 13b.

[0062] Figure 2(a) shows Figure 1 Figure 2(b) shows the vector diagram of the magnetic field in the tire wear measuring device. Figure 1 The contour plots of the magnetic field sensor components in the tire wear measuring device are shown. As shown, the tire wear measuring device 10 has a coin-shaped battery 11 positioned at a location capable of transmitting the magnetic field of the magnetic body 30, and magnetic sensors 12A and 12B positioned at locations capable of detecting the emitted magnetic field from the outer peripheral end 11e of the coin-shaped battery 11. With this configuration, the coin-shaped battery 11 can function as a simulated magnetic yoke, and the emitted magnetic field from the outer peripheral end 11e can be detected by the magnetic sensors 12A and 12B. Thus, by arranging the coin-shaped battery 11 between the magnetic body 30 and the magnetic sensors 12A and 12B, the tire wear measuring device 10 can be made smaller and lighter, and can measure the magnetic field of the magnetic body 30 with high accuracy.

[0063] Figure 3(a) shows Figure 1 The contour plot of the magnetic field sensor detected by the tire wear measuring device, Figure 3(b) shows the contour plot of the magnetic field sensor detected by the device. Figure 8 The contour map of the magnetic field sensor in the tire wear measuring device.

[0064] As shown in Figure 3(a), in the tire wear measuring device 10 of this embodiment, a region with high magnetic flux density in the X-axis direction is formed between the outer peripheral end 11e of the coin-shaped battery 11 and the ends 13a and 13b of the antenna 13. This is formed by the emitted magnetic field induced from the outer peripheral end 11e of the coin-shaped battery 11 to the ends 13a and 13b of the antenna 13. Therefore, by arranging magnetic sensors 12A and 12B with detection axes in the X-axis direction in this region, the magnetic field from the magnetic body 30 can be detected with high precision. Furthermore, by arranging magnetic sensors 12A and 12B between the outer peripheral end 11e of the coin-shaped battery 11 and the ends 13a and 13b of the antenna 13, the magnetic sensors 12A and 12B can be reliably positioned to detect the emitted magnetic field.

[0065] As shown in Figure 3(b), in the conventional tire wear measuring device 100, the magnetic sensors 102A and 102B are positioned closer to the magnetic body 30 than the coin-shaped battery 11, directly detecting the magnetic field from the magnetic body 30, thus making it difficult to achieve small size and light weight.

[0066] Figure 4 It is a schematic representation Figure 1 A diagram illustrating the positional relationship of the magnet 30, coin-shaped battery 11, magnetic sensors 12A and 12B, and the ends 13a and 13b of the antenna 13 in the tire wear measuring device. Figure 4 Schematic representation of the normal 11L from the electrode surface 11d of the coin-shaped battery 11 (refer to) Figure 1 The direction of () refers to the positional relationship when viewed from above along the Y-axis. That is, in Figure 4 In the attached figure, the inner side is the electrode surface 11d side. As shown in the figure, the ends 13a on the magnetic sensor 12A side and 13b on the magnetic sensor 12B side of the antenna 13 are respectively disposed outside the outer periphery 11e of the coin-shaped battery 11, i.e., at a position that does not overlap with the coin-shaped battery 11. Furthermore, the magnetic sensors 12A and 12B are respectively disposed between the outer periphery 11e of the coin-shaped battery 11 and the ends 13a and 13b of the antenna 13.

[0067] exist Figure 4In the figure, when viewed from above along the Y-axis, the outer peripheral end 11e of the coin-shaped battery 11, the magnetic sensor 12A and the end 13a of the antenna 13, and the outer peripheral end 11e of the coin-shaped battery 11, the magnetic sensor 12B and the end 13b of the antenna 13 are configured not to overlap. However, this configuration is only one example; the magnetic sensors 12A and 12B only need to be positioned between the outer peripheral end 11e of the coin-shaped battery 11 and the ends 13a and 13b of the antenna 13. For example, when viewed from above along the Y-axis, the magnetic sensors 12A, the outer peripheral end 11e and the end 13a (part or all), and the magnetic sensors 12B, the outer peripheral end 11e and the end 13b (part or all) can also be configured to overlap.

[0068] The tire wear measuring device 10 includes a magnetic sensor 12A and a magnetic sensor 12B. Magnetic sensor 12A is positioned on one side of the coin-shaped battery 11, separated by the coin-shaped battery 11, and magnetic sensor 12B is positioned on the other side, along the X-axis direction parallel to the electrode surface 11d of the coin-shaped battery 11. In this embodiment, as... Figure 4 As shown, the center O of the electrode surface 11d of the coin-shaped battery 11 overlaps with the magnetic body 30 embedded in the tire 20 and is located on the straight line L connecting the magnetic sensor 12A and the magnetic sensor 12B.

[0069] The straight line L connecting magnetic sensors 12A and 12B is parallel to the X-axis, and both ends 13a and 13b of antenna 13 are located on straight line L. Furthermore, magnetic sensors 12A and 12B are symmetrically arranged with respect to the center O of the electrode surface 11d of the coin-shaped battery 11. Similarly, ends 13a and 13b of antenna 13 are symmetrically arranged with respect to the center O of the electrode surface 11d of the coin-shaped battery 11.

[0070] Furthermore, a magnetic sensor 12A and an end piece 13a are disposed on one side of the coin-shaped battery 11, and a magnetic sensor 12B and an end piece 13b are disposed on the other side. The coin-shaped battery 11 is positioned at a location that overlaps with the magnetic body 30 when viewed from the Y-axis direction.

[0071] Based on the above configuration, the emitted magnetic field Ma detected by magnetic sensor 12A and the emitted magnetic field Mb detected by magnetic sensor 12B have the same magnetic flux density, but their directions are opposite. Therefore, by detecting tire wear 20 based on the outputs of magnetic sensor 12A and magnetic sensor 12B, the redundancy of the tire wear measuring device 10 is improved.

[0072] Furthermore, the external magnetic field, which becomes the noise being measured, affects both magnetic sensor 12A and magnetic sensor 12B. Therefore, by using the difference between the outputs from these two sensors, the influence of the external magnetic field can be eliminated. Since the magnetic fields from the outputs of the two sensors are oriented in opposite directions, by using the difference between the two outputs, the influence of noise can be eliminated, and an output twice the size of the output from one sensor can be obtained. Thus, by eliminating the influence of noise such as external magnetic fields and increasing the output, the wear of tire 20 can be measured with high accuracy.

[0073] The magnetic material 30 is formed by dispersing hard magnetic material powder (magnetic powder) into a polymer material, magnetizing it in one direction, and embedding it in the tread portion with the magnetization direction aligned with the radial direction of the tire. Preferably, the polymer material is a rubber material with the same proportions as the tread rubber composition used in the tread portion.

[0074] The magnetic body 30 is preferably configured to have a magnetic flux density of 1 mT or more on its surface. Furthermore, from the viewpoint of being able to reliably measure the magnetic flux density of the magnetic body without being affected by the Earth's magnetic field, it is preferable to have a magnetic flux density of 0.05 mT or more at the measurement position where the magnetic sensors 12A and 12B are installed, and more preferably to have a magnetic flux density of 0.5 mT or more.

[0075] On the other hand, from the viewpoint of avoiding adverse effects of the magnetic force of the magnetic body 30 on other electronic devices in the vehicle, the surface magnetic flux density of the magnetic body 30 is preferably 600 mT or less. From the viewpoint of avoiding attracting metal pieces such as nails that have fallen on the road surface while driving, the surface magnetic flux density of the magnetic body 30 is preferably 60 mT or less. In addition, the surface magnetic flux density of the magnetic body is a value measured by bringing a magnetometer into direct contact with the surface of the magnetized magnetic body 30.

[0076] <Variation Example>

[0077] Figure 5 This is a cross-sectional view schematically illustrating the configuration of a modified example of the tire wear measuring device according to this embodiment. The tire wear measuring device 50 shown in this figure differs from the tire wear measuring device 10 described above in that it has magnetic sensors 12A and 12B, and the ends 13a and 13b of the antenna 13 disposed on the surface 51d of the substrate 51 on the side of the coin-shaped battery 11. That is, the tire wear measuring device 50 has magnetic sensors 12A and 12B, and the ends 13a and 13b of the antenna 13 disposed on the same plane of the substrate 51 parallel to the electrode surface 11d of the coin-shaped battery 11.

[0078] Figure 6(a) shows Figure 5 A vector diagram of the magnetic field in the tire wear measuring device. Figure 6(b) shows... Figure 5The figures show contour plots of the magnetic field sensor detection components in the tire wear measuring device. As shown in these figures, by arranging magnetic sensors 12A and 12B and the ends 13a and 13b of antenna 13 on the same plane, the magnetic field emitted from the outer peripheral end 11e of the coin-shaped battery 11 can be guided to the ends 13a and 13b of antenna 13, making the detectable direction of magnetic sensors 12A and 12B on the substrate 51 along the X-axis. Therefore, the detection accuracy of the tire wear measuring device 50 becomes good.

[0079] Figure 10 This is a cross-sectional view schematically illustrating the configuration of other variations of the tire wear measuring device of the present invention. As shown in this figure, the tire wear measuring device 60 and the tire wear measuring device 10 (see reference...) Figure 1 The difference lies in that it has a coil 61 positioned within the magnetic field of the magnetic body 30, which can utilize the induced current generated in the coil 61 by the rotation of the tire 20 as an operating power source. The tire wear measuring device 60 utilizes the change in position of the magnetic body 30 embedded in the tread 23 of the tire 20 by the deformation of the tire 20 as it rotates to generate electricity.

[0080] Coil 61 is positioned between a coin-shaped battery 11, which also functions as a magnetizing component, and a magnetic body 30 embedded in the tread portion 23 of the tire 20. The magnetic flux density from the magnetic body 30 passing through coil 61 varies due to deformation and vibration accompanying the rotation of the tire 20. Figure 10 The change in magnetic flux density along the Y-axis, indicated by the arrows on both sides of the hollow core, generates an electromotive force through the induced current produced in coil 61. Therefore, this electromotive force is used as a power source for the tire wear measuring device 60, for example, during startup or communication.

[0081] The tire wear measuring device 60 uses the change in magnetic flux density from the magnetic field of the magnetic body 30, which accompanies the rotation and vibration of the tire 20, to induce a current in the coil 61, thereby generating electricity. Therefore, the generated electricity can be used for various purposes while keeping the tire wear measuring device 60 small and lightweight. In this way, by converting the change in the relative position between the magnetic body 30 and the coil 61 caused by the rotation of the tire 20 into electrical energy, the burden of power consumption by the coin-type battery 11 can be reduced.

[0082] The magnetic field between the magnetic body 30 and the coin-shaped battery 11 increases in the Y-axis direction due to the magnetic field collected on the surface of the coin-shaped battery 11. Generally, the magnetic flux passing through the coil has a component orthogonal to the coil (…). Figure 10When the Y-axis component of the magnetic flux through the coil is large, the change in magnetic flux through the coil is greater, thus generating a larger induced current in the coil. Therefore, from the perspective of the magnetic body 30, the coil 61 is positioned on the side of the coin-shaped battery 11 and close to the magnetic body 30. This increases the induced current generated in the coil 61 as the tire 20 rotates, enabling efficient power generation.

[0083] The electromotive force (EMF) generated in coil 61 varies depending on the magnitude and degree of change of the magnetic flux density from the magnetic body 30. That is, the EMF generated in coil 61 reflects the state of tire 20; therefore, the EMF generated in coil 61 can also be used to detect the state of tire 20. For example, when the magnetic body 30 embedded in the tread 23 decreases with wear of tire 20, the magnetic flux density from the magnetic body 30 decreases; therefore, the change in magnetic flux density from the magnetic body 30 also decreases with the rotation of tire 20. Consequently, the EMF (induced current) generated in coil 61 changes according to the degree of wear of tire 20. Therefore, tire wear can also be detected based on the EMF generated in coil 61. In this case, as a result of wear from… Figure 10 The tire wear measuring device 60 can also be implemented by removing the magnetic sensors 12A and 12B.

[0084] The coil 61 is electrically connected to a storage unit (not shown). The storage unit includes a rectifier circuit and a charging circuit, capable of charging a capacitor with the induced current generated by changes in magnetic flux density. The rectifier circuit can, for example, use a rectifier element that rectifies the induced current (alternating current) generated in the coil 61. The charging circuit can, for example, use a capacitor of the electrostatic capacitor type that stores the charge of the induced current. By using the power held by the capacitor during startup and communication of the tire wear measuring device 60, the load on the coin-type battery 11 is reduced, extending the period (lifespan) during continuous use of the tire wear measuring device 60. Furthermore, when the coin-type battery 11 is a rechargeable battery, it can sometimes be used as the storage unit, omitting the aforementioned capacitor. In this case, the storage unit has a charging / discharging circuit instead of a charging circuit.

[0085] In addition, Figure 10 The diagram shows a way in which the magnetic body 30 deforms in conjunction with the deformation of the tire 20. However, it is not limited to this method, as long as the magnetic flux density in the coil 61 from the magnetic body 30 changes due to the deformation of the tire 20. For example, it could be configured such that, along with the deformation of the tire 20, it is not the magnetic body 30 but the coil 61 that deforms, thereby changing the magnetic flux density of the magnetic field from the magnetic body 30 in the coil 61.

[0086] Figure 11This is a cross-sectional view schematically illustrating the configuration of a power generation device according to an embodiment of the present invention. As shown in the figure, the power generation device 70 includes a magnetic body 30 embedded in a tire 20 and a coil 61 disposed within the magnetic field range of the magnetic body 30. The relative position of the magnetic body 30 and the coil 61 changes with the rotation of the tire 20, and power is generated by means of the change in magnetic flux density through the coil 61 caused by the change in the relative position.

[0087] Furthermore, the power generation device 70 includes a coin-shaped battery 11, which is a secondary battery type and serves as a magnetic component, and a coil 61 is disposed between the coin-shaped battery 11 and the magnetic body 30. Therefore, the induced current generated in the coil 61 as the tire 20 rotates can be increased, and power generation can be carried out effectively.

[0088] In addition, Figure 11 Although antenna 13 is shown in the diagram, it can be removed from the configuration if it is not needed. For example, consider a configuration in which power is supplied from power generation device 70 to a sensor that is separately installed from power generation device 70, where an antenna is provided on the sensor side to enable communication.

[0089] The embodiments described above are provided for ease of understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments also include the spirit of all design variations and equivalents falling within the scope of the present invention. For example, it could also be that... Figure 11 The power generation device 70 shown includes a measuring unit that measures the amplitude and frequency changes of the electromotive force generated in the coil 61. Based on the signal obtained from the measuring unit, the condition of the tire, including its wear state, is detected. When the electromotive force generated by the coil 61 becomes the signal source measured by the measuring unit, the power generation device 70 can be positioned as a detection device that outputs information related to the tire's condition. Furthermore, the coin-type battery 11 functions as a magnetic component in the power generation device 70, but the magnetic component can be provided separately from the coin-type battery 11. When the power generation device 70 functions as a detection device, the coin-type battery 11 may not be provided.

[0090] Example

[0091] For those who have Figure 1 The tire wear measuring device 10 of the present invention, as shown in the diagram, and the configuration of removing the antenna 13 from the tire wear measuring device, are used to measure tire wear. Figure 8 The output of the conventional tire wear measuring device 100 is increased to what extent. In any case, a magnetic body 30 with a surface magnetic flux density of 26 mT is used.

[0092] Figure 12(a) is a perspective view showing the outline and internal structure of the tire wear measuring device of Example 1 and Example 2, and Figure 12(b) is a perspective view showing the outline and internal structure of the tire wear measuring device of Comparative Example 1. The results obtained from the measurement output of these tire wear measuring devices are shown in Table 1 and... Figure 13 middle.

[0093] Table 1

[0094] Table 1 Example 1 Example 2 Comparative Example 1 non-magnetic yoke With magnetic yoke D1(mm) 16.0 16.0 20.7 D2 (mm) 21.2 21.2 17 Dimensions (mm) 28×36×15 28×36×15 36×47×24 Volume ratio (%) 37.2 37.2 100.0 Weight (g) 21 21 42 Weight percentage (%) 50.0 50.0 100.0 Output ratio (%) 123.0 145.7 100.0

[0095] As shown in Table 1 and Figure 13 As shown, the magnetic field of the magnetic body is transmitted through a coin-shaped battery, and the emitted magnetic field emitted from the outer peripheral end of the coin-shaped battery is detected by a magnetic sensor. Therefore, compared with the past, the capacity and weight can be greatly reduced, and the detection accuracy can be improved by high output.

[0096] Industrial availability

[0097] This invention can be applied to a tire wear measuring device that can determine the wear condition of a tire without visual inspection.

[0098] Explanation of symbols

[0099] 10, 50, 60: Tire wear measuring device; 11: Coin-type battery (battery, magnetic collecting component, magnetic component); 11L: Normal; 11d: Electrode surface; 11e: Outer peripheral end; 11f: Surface; 12A: Magnetic sensor (first sensor); 12B: Magnetic sensor (second sensor); 13: Antenna; 13a: End (first end, end on the magnetic sensor side); 13b: End (second end, end on the magnetic sensor side); 20: Tire; 21: Inner side; 22: Outer side; 23: Tire tread; 30: Magnetic body (magnet); 51: Substrate; 51d: Surface; 61: Coil; 70: Power generation device; 100: Tire wear measuring device; 101: Coin-type battery; 101e: Outer peripheral end; 102A, 102B: Magnetic sensor; M: Magnetic field; Ma, Mb: Emitted magnetic field; O: Center; D1, D2: Distance.

Claims

1. A tire wear measuring device, comprising a magnetic sensor and a magnetic collecting component, for detecting tire wear based on the magnetic field of a magnet embedded in the tire, characterized in that, The aforementioned magnetic collecting component can transmit the magnetic field of the aforementioned magnet, and release the magnetic field of the aforementioned magnet as an extrusion magnetic field from its outer peripheral end. The aforementioned magnetic sensor is positioned at a location capable of detecting the emitted magnetic field. The aforementioned tire wear measuring device includes a magnetic field sensing component that senses the emitted magnetic field. The aforementioned magnetic collecting component is a coin-shaped battery. When viewed from above along the normal direction of the electrode surface of the coin-shaped battery, The end of the magnetic sensor side of the aforementioned magnetic field sensing component is disposed on the outer side of the outer peripheral end of the aforementioned coin-shaped battery. The magnetic sensor is disposed between the coin-shaped battery and the end of the magnetic field sensing component.

2. The tire wear measuring device according to claim 1, wherein, The aforementioned coin-shaped battery is configured with its electrode surfaces facing the aforementioned magnet.

3. The tire wear measuring device according to claim 1, wherein, The aforementioned magnetic field sensing component is an antenna that acts as a waveguide for emitting and receiving electromagnetic waves.

4. The tire wear measuring device according to claim 1, wherein, The detectable direction of the aforementioned magnetic sensor is parallel to the electrode surface of the aforementioned coin-shaped battery. The aforementioned end of the magnetic field sensing component and the aforementioned magnetic sensor are disposed on the same plane parallel to the electrode surface of the aforementioned coin-shaped battery.

5. The tire wear measuring device according to claim 1, wherein, The aforementioned magnetic sensor includes a first sensor and a second sensor. In a direction parallel to the electrode surface of the coin-shaped battery, with respect to the coin-shaped battery, the first sensor is disposed on one side and the second sensor is disposed on the other side. Tire wear is detected based on the outputs of the first sensor and the second sensor.

6. The tire wear measuring device according to claim 5, wherein, When viewed from above in the direction of the normal to the electrode surface of the coin-shaped battery, the center of the electrode surface of the coin-shaped battery overlaps with the magnet embedded in the tire and is located on the straight line connecting the first sensor and the second sensor.

7. The tire wear measuring device according to claim 1, wherein, The device has a coil positioned within the magnetic field range of the magnet, and can utilize the induced current generated in the coil by the rotation of the tire as an operating power source.

8. The tire wear measuring device according to claim 7, wherein, The coil is positioned between the magnetic collecting component and the magnet.

9. A tire wear measuring device, comprising a magnetic sensor and a magnetic collecting component, for detecting tire wear based on the magnetic field of a magnet embedded in the tire, characterized in that, The aforementioned magnetic collecting component can transmit the magnetic field of the aforementioned magnet, and release the magnetic field of the aforementioned magnet as an extrusion magnetic field from its outer peripheral end. The aforementioned magnetic sensor is positioned at a location capable of detecting the emitted magnetic field. The aforementioned tire wear measuring device includes a magnetic field sensing component that senses the emitted magnetic field. The aforementioned magnetic sensor includes a first sensor and a second sensor. The aforementioned magnetic field sensing component has a first end and a second end as the ends of the aforementioned magnetic sensor side. The aforementioned magnetic collecting component is a coin-shaped battery. In a direction parallel to the electrode surface of the coin-shaped battery, with the first sensor and the first end portion disposed on one side, and the second sensor and the second end portion disposed on the other side, separated by the coin-shaped battery. Tire wear is detected based on the outputs of the first sensor and the second sensor.

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