WO2023002666A1

WO2023002666A1 - Tire wear sensor, tire degree-of-wear measurement system, tire degree-of-wear assessment device, and tire degree-of-wear assessment method

Info

Publication number: WO2023002666A1
Application number: PCT/JP2022/009309
Authority: WO
Inventors: 学田村; 裕樹大野; 利恵黒澤; 佑貴今井; 徳男中村; 雅史金子; 一成瀬下
Original assignee: アルプスアルパイン株式会社
Priority date: 2021-07-21
Filing date: 2022-03-04
Publication date: 2023-01-26

Abstract

This tire wear sensor 1 can measure the degree of wear of a tread section of a tire without having a magnetic body embedded in the tread section of the tire, the magnetic body causing iron nails and the like to be drawn into a surface of the tread section. The tire wear sensor comprises: a magnet 11 that senses the degree of wear of a tire 2 on the basis of changes in magnetism and that is disposed on an inner side 21 of the tire 2; and a magnetism sensor 12 that is disposed further on a rotational center O side of the tire 2 with respect to the magnet 11 and that can sense magnetism produced by the magnet 11. When a sensing target section 24 of a tread section 23 in the tire 2 has come into contact with a magnetic body 3 located on an outer side 22 of the tire 2, the degree of wear of the tire 2 is measured as a result of the magnetism sensor 12 sensing the magnetism produced by the magnet 11.

Description

Tire wear sensor, tire wear measurement system, tire wear evaluation device, and tire wear evaluation method

The present invention relates to a tire wear sensor that detects the degree of wear of a tire, a wear degree measurement system using the tire wear sensor, a wear degree evaluation device, and a wear degree evaluation method.

As tire wear progresses, grip performance when driving on a road surface and drainage performance for discharging water between the tire and the road surface when driving on a wet road surface deteriorate. Therefore, it is necessary for drivers and vehicle managers to check the worn state of the tread portion of the tire and replace the tire before the usage limit is exceeded in order to ensure safety. Visual inspection is performed by confirming the slip sign provided in the groove of the tire, but there is a risk of erroneously evaluating the state of wear. Moreover, since the inspection work is complicated, it is conceivable that some users do not perform the inspection. If the wear state of the tread portion is incorrectly evaluated or not evaluated, the tire exceeding the service limit may continue to be used, which is undesirable from the viewpoint of safety.
Therefore, there has been proposed a tire wear measurement system that measures the degree of wear of a tire by a method other than visual observation and detects that the performance of the tire has deteriorated. For example, in Patent Document 1, a magnetic sensor capable of detecting magnetism emitted by a tire wear detection magnet embedded in the tread portion of a tire is provided at a position facing the tire wear detection magnet on the inner surface of the tire. A tire wear sensor is described. This device detects the degree of wear of the tire by measuring changes in the magnetic field caused by the wear of the embedded magnet along with the wear of the tread portion of the tire.

JP 2019-203831 A

The tire wear sensor described in Patent Document 1 measures the degree of wear of the tread portion of the tire based on changes in magnetism due to wear of magnets embedded in the tread portion. For this reason, the magnet is embedded in the tire so that one of the magnets is exposed on the surface of the tread portion and worn together with the tread portion. Therefore, additional work is required to incorporate the magnet into the tread portion of a typical tire. In addition, the tire may be damaged by iron nails or the like attracted by the magnetism of the magnet exposed on the tread surface, resulting in puncture.
An object of the present invention is to provide a tire wear sensor capable of measuring the degree of wear of the tread portion of a tire without embedding a magnet in the tread portion of the tire, which causes iron nails or the like to be attracted to the tread surface, and to use the tire wear sensor. It is an object of the present invention to provide a wear measurement system, a wear evaluation device, and a wear evaluation method.

The present invention has the following configurations as means for solving the above-described problems.
A tire wear sensor placed inside the tire that detects the degree of wear of the tire based on changes in magnetism, wherein a magnet placed inside the tire is placed closer to the center of rotation of the tire than the magnet. and a magnetic sensor capable of detecting the magnetism emitted by the magnet, wherein the magnet is detected by the magnetic sensor when a detection target portion of the tread portion of the tire contacts a magnetic body located outside the tire. A tire wear sensor that measures the degree of wear of the tire by detecting magnetism emitted by a.

As the distance between the magnet and the magnetic material changes as the tread wears, the state of magnetism changes when the part to be detected of the tire comes into contact with the magnetic material located on the outside of the tire. Therefore, the wear of the tread portion can be measured by detecting changes in the state of magnetism using the magnetic sensor.

A tire wear sensor has two magnetic sensors, and the two magnetic sensors are arranged at positions symmetrical with respect to the magnet when viewed along the radial direction of the tire from the rotation center side. may be
A tire wear sensor has two magnetic sensors and two magnets, and each of the two magnetic sensors and the two magnets has a reference point when viewed along the radial direction of the tire from the rotation center side. and the magnetic sensor and the magnet may be arranged on the same straight line passing through the reference point. In this case, the magnetic sensor may be arranged at a position farther from the reference point than the magnet.

By providing two magnetic sensors and two magnets as described above and using the outputs of the two magnetic sensors, the effects of noise can be suppressed. Also, since the two outputs are of the same magnitude but in opposite directions, a large output can be obtained as the difference between the two outputs. Since the outputs obtained from the two magnetic sensors have the same absolute value, even if one of them fails, the output of the other can be used to evaluate the degree of tire wear. Therefore, the redundancy of tire wear sensors is improved.

The magnet may have a soft magnetic layer made of a soft magnetic material on one end side in the magnetization direction, and may be arranged so that the one end side in the magnetization direction is closer to the center of the tire than the other end side.
With this configuration, the magnetic field detected by the magnetic sensor provided on the center side of the tire can be reduced by the soft magnetic layer. Therefore, magnetic saturation of the magnetic sensor is less likely to occur, and the measurement accuracy of the tire wear sensor is stabilized.

A tire wear sensor placed inside the tire that detects the degree of wear of the tire based on changes in magnetism, comprising a magnetic sensor placed inside the tire, wherein the magnetic sensor is located on the tread of the tire. When the detection target portion of the tire comes into contact with a magnetism generator that emits a predetermined magnetism located outside the tire, the magnetic sensor detects the magnetism emitted by the magnetism generator to measure the degree of wear of the tire. A tire wear sensor characterized by:
The tire wear sensor can measure the degree of wear of the tire by detecting a change in the magnetism from the magnetism generator outside the tire that accompanies wear of the tire with a magnetic sensor arranged inside the tire.

The magnetic field generator is configured such that a plurality of pairs of different magnetic poles are alternately arranged, and the magnetic sensor moves the magnetic field generator along the direction in which the magnetic poles are arranged while the magnetic field generator is in contact with the tread portion. The magnetism emitted by the magnetism generator may be detected when the body is moved.

The magnetism generator is an electromagnet that generates magnetism at a contact point with a contacting object, and the magnetic sensor detects that the electromagnet is generated when the tire is rolling in the circumferential direction of the tire while being in contact with the electromagnet. The emitted magnetism may be detected.
The electromagnet may magnetize a wire embedded in the tire by contacting the surface of the tire, and the magnetic sensor may detect the magnetism generated by the magnetized wire.

The tire wear sensor includes a device ID storage unit that stores a device ID unique to the tire wear sensor, and a wear degree output unit that outputs the measured wear degree of the tire and the device ID in association with each other. good too.
With this configuration, the measurement value of the degree of wear of the tire and the device ID can be output in association with each other, so that the tire whose degree of wear exceeds the threshold and needs to be replaced can be specified based on the device ID.

A tire wear measurement system comprising a tire wear sensor arranged inside the tire and a magnetic body arranged outside the tire for detecting the degree of wear of the tire based on a change in magnetism, The tire wear sensor has a magnet arranged inside the tire and a magnetic sensor arranged closer to the center of rotation of the tire than the magnet and capable of detecting magnetism emitted by the magnet. A system for measuring the degree of wear of a tire, wherein the degree of wear of the tire is measured by detecting the magnetism generated by the magnet with the magnetic sensor when the detection target portion of the tread portion contacts the magnetic body. .
With this configuration, the degree of wear of the tread can be measured by detecting changes in the magnetism from the magnet reaching the magnetic sensor as the wear of the tread progresses.

The length of the magnetic body in the longitudinal direction is preferably greater than the length of the outer periphery of the tire. With this configuration, the detection target portion of the tread portion can be reliably brought into contact with the magnetic material, so the wear amount of the tire can be measured with high accuracy.

an ID information storage unit that associates and stores a device ID of a tire wear sensor and a tire to which the tire wear sensor is attached; a measurement value acquisition unit that acquires the degree of wear of the tire associated with the device ID; a threshold storage unit that stores a threshold value of the degree of wear of the tire; and a device ID and ID information storage unit that are associated with the degree of wear of the tire when the degree of wear of the tire exceeds the threshold value. and a tire identification unit that identifies the tire that needs to be replaced based on the information of the tire wear degree evaluation device.
With this configuration, the wear degree evaluation device can identify the tire that needs to be replaced based on the device ID of the tire wear sensor.

The ID information storage unit stores the device ID, the tire, and the type of vehicle on which the tire wear sensor is mounted, and the threshold storage unit stores the threshold according to the type of vehicle. The tire specifying unit stores information on the tire that needs to be replaced based on the information in the ID information storage unit when the degree of wear of the tire exceeds the threshold value corresponding to the type of the vehicle. Tires may be specified.
Whether or not a tire needs to be replaced can be determined more appropriately according to the type of vehicle and the mode of use of the vehicle by using the threshold value according to the type of vehicle and the type of vehicle.

A device ID unique to the tire wear sensor and tire information that can identify the tire to which the tire wear sensor is attached are associated and output, the tire wear sensor measures the degree of wear of the tire, and the measured wear A method for evaluating the degree of wear of a tire, characterized in that the degree of tire wear is associated with the device ID of the tire wear sensor that measured the degree of wear and is output.
With this configuration, a tire requiring replacement can be specified based on the device ID of the tire wear sensor.

The tire wear sensor may measure the degree of wear of the tire when a vehicle having the tire passes over a magnetic body or a magnetic field generator.
For example, by arranging a magnetic body or a magnetic field generator at the gate of a business office to which vehicles such as trucks and buses belong, tire wear can be automatically measured at departure and arrival. In addition, in the case of trucks where the load on the tires varies depending on the cargo, there is no cargo at the time of departure and arrival, so it is possible to accurately measure the degree of wear of the tires while excluding the influence of the cargo.

A device ID unique to a tire wear sensor and tire information capable of specifying the tire to which the tire wear sensor is attached are acquired, both are associated and stored, the degree of wear of the tire is acquired, and the wear is obtained. and a threshold to obtain the device ID associated with the wear degree, and based on the device ID and the tire information associated with the device ID, the tire to which the tire wear sensor is attached. A method for evaluating the degree of wear of a tire, characterized by specifying
With this configuration, the tire that needs to be replaced can be specified based on the device ID of the tire wear sensor.

According to the present invention, tire wear can be measured without embedding a magnet in the tire, so punctures caused by magnets embedded in the tire attracting metal such as nails can be suppressed.

Cross-sectional view of a state in which a tire wear sensor is provided FIG. 1A is an enlarged cross-sectional view of region S in FIG. 1A Cross-sectional view of magnetism near detection target Cross-sectional view of magnetism when in contact with a magnetic body Sectional view of a modified tire wear sensor Top view of magnetic body and magnetic sensor Cross-sectional view showing the relationship between the magnetism in the vicinity of the detection target and the two magnetic sensors Cross-sectional view showing magnetism when in contact with a magnetic body Cross-sectional view of another modified tire wear sensor Top view of magnetic body and magnetic sensor Sectional drawing which shows the magnet of a modification typically Cross-sectional view showing magnetism in the vicinity of the detection target Cross section of wear measurement system Perspective view of wear measurement system Top view of magnetic generator of wear measurement system Perspective view of a modification of the wear measurement system Plan view of magnetism generator of modification of wear measurement system Sectional view of another modification of the wear measurement system Schematic diagram of the whole wear measurement system with a tire wear sensor and a magnetic body Functional block diagram of the tire wear sensor Functional block diagram of management device Flow chart of tire wear evaluation method

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same numbers are assigned to the same members in each drawing, and the description thereof is omitted as appropriate.
FIG. 1A is a cross-sectional view schematically showing a tire wear sensor 1 provided on a tire 2, and FIG. 1B is a cross-sectional view enlarging a region S in FIG. 1A. The tire wear sensor 1 has a magnet 11 arranged inside 21 of the tire 2 and a magnetic sensor 12 arranged closer to the rotation center O of the tire 2 than the magnet 11 and capable of detecting the magnetism emitted by the magnet 11 . are doing. The tire wear sensor 1 is arranged on the inner side 21 of the tire 2, measures the magnetism from the magnet 11 when the detection target portion 24 of the tread portion 23 comes into contact with the magnetic body 3, and detects changes in the measured magnetism. to detect the degree of wear of the tire 2 . Although the degree of wear includes the depth of the groove of the tire 2, the tire wear sensor 1 may detect information about other tires 2 together with the degree of wear.

The magnet 11 can be an alloy magnet, a ferrite magnet, a magneto-earth magnet, or a rubber magnet or plastic magnet formed by dispersing these particles (magnetic powder) in a polymer material. The magnet 11 is arranged in the tire wear sensor 1 in such a posture that its magnetization direction matches the radial direction (Z-axis direction) of the tire 2 . As the polymer material used for the rubber magnet, a rubber material having the same composition as the tread rubber composition used for the tread portion 23 of the tire 2 may be used.

The magnet 11 preferably has a magnetic flux density of 1 mT or more on the surface of the pole tip on the magnetic sensor 12 side. From the viewpoint of preventing the magnetism of the magnet 11 from adversely affecting other on-vehicle electronic devices, the surface magnetic flux density at the pole tip of the magnet 11 is preferably 600 mT or less. The surface magnetic flux density is a value measured by directly contacting the magnetized surface of the magnet 11 with a Tesla meter.

The magnetic sensor 12 detects the state of magnetism and converts it into an electric signal, and faces the magnet 11 in the tire wear sensor 1 arranged inside 21 of the tire 2, and can detect the magnetism emitted by the magnet 11. are placed in a good position. Examples of the magnetic sensor 12 include a GMR sensor, a TMR sensor, and a Hall sensor using the Hall effect.

2A is a cross-sectional view schematically showing the magnetism M emitted by the magnet 11 in the vicinity of the detection target portion 24 of the tread portion 23 of the tire 2, and FIG. 3 is a cross-sectional view schematically showing the magnetism M when in contact with the body 3; FIG.

In the tire wear sensor 1, a magnet 11 and a magnetic sensor 12 are arranged in a case separated in the Z-axis direction (radial direction of the tire 2), and a detection target portion 24 is a magnetic body positioned outside 22 of the tire 2. 3, the magnetic sensor 12 detects the magnetism M emitted by the magnet 11 to measure the degree of wear of the tire 2. - 特許庁A distance D between the magnet 11 provided on the inner side 21 of the tire 2 and the magnetic body 3 on the outer side 22 of the tire 2 changes according to the degree of wear of the detection target portion 24 . When the distance D changes, the influence of the magnetic body 3 on the magnet 11 also changes, and the magnetism M detected by the magnetic sensor 12 also changes. In other words, when the tire 2 wears, the magnetism M detected by the magnetic sensor 12 changes.

That is, when the detection target portion 24 having the tire wear sensor 1 arranged inside 21 passes over the magnetic body 3 , the magnetism M from the magnet 11 is measured by the magnetic sensor 12 , and the magnetic field from the magnet 11 to the magnetic body 3 is measured. can be estimated. Since the distance D becomes smaller as the wear of the tread portion 23 of the tire 2 progresses, the degree of wear of the tire 2 can be evaluated based on the magnetic field measurement value by the magnetic sensor 12 . Therefore, the degree of wear of the tread portion 23 (the degree of wear of the tire 2 ) can be evaluated by measuring the magnetism M of the magnet 11 with the magnetic sensor 12 without embedding the magnet 11 in the tread portion 23 of the tire 2 .

The magnetic material 3 is composed of a magnetic material that affects the magnetism M. For the magnetic body 3, for example, a plate of a ferromagnetic material such as iron, nickel, cobalt, and alloys thereof can be used. Further, the present invention can be implemented as a wear measuring system including the tire wear sensor 1 and the magnetic body 3 .

FIG. 3A is a partial cross-sectional view schematically showing a tire wear sensor 4 according to a modification. The tire wear sensor 4 differs from the tire wear sensor 1 in that it has two

magnetic sensors

42A and 42B. In the following description, the

magnetic sensors

42A and 42B are appropriately referred to as the magnetic sensor 42 when the

magnetic sensors

42A and 42B are not distinguished.

Magnets

51A and 51B and

magnetic sensors

52A and 52B, which will be described later, are similarly referred to as magnets 51 and magnetic sensors 52 as appropriate.

The tire wear sensor 4 detects the magnetism of the magnet 11 based on differential signals from the two

magnetic sensors

42A and 42B. The magnetic sensor 42 detects magnetism in the Y-axis direction intersecting the magnetization direction (Z-axis direction) of the magnet 11 . By using the magnetic difference output detected by the magnetic sensor 42, the detection accuracy of the degree of wear of the tire 2 is improved. Note that the tire wear sensor 4 may include a magnetic induction member (not shown). By arranging the magnetic sensor 42 between the magnet 11 and the magnetic induction member, the sensitivity of the magnetic sensor 42 is improved.

3B is a plan view schematically showing the positional relationship between the magnet 11 and the

magnetic sensors

42A and 42B in the tire wear sensor 4. FIG. This figure schematically shows the positional relationship viewed from the Z-axis direction, which is the magnetization direction of the magnet 11 . The

magnetic sensors

42A and 42B are arranged so as to have portions located outside the outer shell of the magnet 11 when viewed from the magnetization direction. With this configuration, the tire wear sensor 4 can accurately measure changes in magnetism in the Y-axis direction as the degree of wear of the tire 2 progresses.

The two

magnetic sensors

42A and 42B are arranged at point-symmetrical positions with respect to the magnet 11 when viewed along the radial direction of the tire 2 from the rotation center O side of the tire 2 (see FIG. 1A). That is, as shown in FIG. 1A, when the tire wear sensor 4 is positioned at the ground contact portion, that is, the lower end of the tire 2, when viewed from above along the Z-axis, the magnetic sensors 42A are positioned point-symmetrically about the magnet 11. , 42B are arranged.

4A is a cross-sectional view schematically showing the relationship between the magnetism M emitted by the magnet 11 and the two

magnetic sensors

42A and 42B in the vicinity of the detection target portion 24 of the tread portion 23 of the tire 2. FIG. 4B is a cross-sectional view schematically showing magnetism when the detection target portion 24 contacts the magnetic body 3 positioned on the outer side 22 of the tire 2. FIG. Since the

magnetic sensors

42A and 42B are arranged point-symmetrically about the magnet 11, the magnetism M measured by the

magnetic sensors

42A and 42B is the same in opposite directions. On the other hand, noise caused by influences such as geomagnetism has the same magnitude and direction. Therefore, by taking the difference between the outputs of the

magnetic sensors

42A and 42B, noise can be removed and a large output can be obtained. In addition, since the two magnetic sensors 42 each detect the magnetism M of the same magnitude, if a problem occurs in one of them, the degree of wear can be measured using only the output from the other magnetic sensor 42 . Therefore, the redundancy of the tire wear sensor 4 is improved.

FIG. 5A is a partial cross-sectional view schematically showing a tire wear sensor 5 according to another modification, and FIG. 5B schematically shows the positional relationship between

magnets

51A and 51B and

magnetic sensors

52A and 52B in the tire wear sensor 5. 2 is a schematic plan view; FIG. As shown in these figures, tire wear sensor 5 differs from tire wear sensor 1 in that it has two magnets 51 and two magnetic sensors 52 .

The tire wear sensor 5 is provided with one magnetic sensor 52 corresponding to each magnet 51 . The

magnets

51A, 51B and the

magnetic sensors

52A, 52B are arranged at symmetrical positions with respect to the reference point B when viewed along the Z-axis from the rotation center O (see FIG. 1A) side of the tire 2. ing. Further, the magnetic sensors 52 are arranged at positions farther from the reference point B than the magnets 51 are.

A reference point B is a (virtual) point on the bottom surface 53 of the tire wear sensor 5 obtained by projecting the midpoint of a line connecting the two magnetic sensors 52 in the radial direction of the tire 2 from the rotation center O side. It is also a (virtual) point on the bottom surface 53 of the tire wear sensor 5 projected in the radial direction of the tire 2 from the rotation center side of the midpoint of the line segment connecting 51 . That is, the midpoint of the line segment connecting the two magnetic sensors 52 and the midpoint of the line segment connecting the two magnets 51 overlap when projected onto the bottom surface.

The two magnets 51 and the two magnetic sensors 52 are arranged on the same straight line P passing through the reference point B (on the same straight line). That is, when the two magnets 51 and the two magnetic sensors 52 are projected onto the bottom surface 53 of the tire wear sensor 5 along the Z-axis direction, which is the radial direction of the tire 2, from the rotation center O (see FIG. 1A) side. , so as to be positioned on the same straight line P passing through the reference point B.

The number of magnets 51 and magnetic sensors 52 is not limited to two sets of tire wear sensors 5, and may be three sets or more. Also, the number of magnets 51 and magnetic sensors 52 forming a set may not be the same. For example, a configuration in which the magnetism M from one magnet 51 is detected by a plurality of magnetic sensors 52 or a configuration in which the magnetism M from a plurality of magnets 51 is detected by one magnet 51 may be employed.

FIG. 6 is a cross-sectional view schematically showing a magnet 13 according to a modification. The magnet 13 has a soft magnetic layer 13b made of a soft magnetic material on one end 131 side in the magnetization direction (Z-axis direction) of the hard magnetic layer 13a made of a hard magnetic material, that is, on the magnetic sensor 12 side.

The hard magnetic layer 13a is arranged so that one end 131 side in the magnetization direction is closer to the rotation center O (see FIG. 1A) of the tire 2 than the other end 132 side. The magnetism M is guided in the direction parallel to the Y-axis by the hard magnetic layer 13a provided on the one end 131 side, and the state of the magnetism M from the magnet 11 is differentiated between the inner side 21 and the outer side 22 of the tire 2. be able to. That is, by providing the soft magnetic layer 13b on the one end 131 side of the hard magnetic layer 13a, the magnetism M of the magnet 11 shown in FIGS. The magnetism M that spreads toward the tire 2 can be reduced, and the magnetism M that spreads toward the opposite side of the rotation center O on the outer side 22 of the tire 2 can be increased.

If the magnetism M on the side of the magnetic sensor 12 is large in the initial state where the tire 2 is not worn, the magnetic sensor 12 is likely to be saturated. . By reducing the magnetism M on the side of the magnetic sensor 12 in the initial state, magnetic saturation of the magnetic sensor 12 can be suppressed.

In addition, the magnetic sensor 12 measures variations in the magnetism M caused by changes in the distance D (see FIG. 2B) between the magnet 11 and the magnetic body 3 due to wear of the tire 2 . For this reason, the distribution of the magnetism M tends to change more easily when the stronger magnetism M is emitted from the outer side 22 of the tire 2, and the fluctuation of the magnetism M detected by the magnetic sensor 12 increases.

Therefore, by using the magnet 13 provided with the soft magnetic layer 13b made of a soft magnetic material on the magnetic sensor 12 side, the magnetism M on the inside 21 of the tire 2 is reduced and the magnetism M on the outside is increased. The detection accuracy of the magnetism M by the sensor 12 is improved.

The hard magnetic layer 13a is not particularly limited as long as it is made of a hard magnetic material. Examples include ferrite (hard ferrite) containing iron oxide as a main component, alnico (Al--Ni--Co alloy), and samarium-cobalt. The material forming the soft magnetic layer 13b is not particularly limited as long as it is a soft magnetic material. Examples include permalloy (Fe--Ni alloy), sendust (Fe--Si--Al alloy) which is another iron-based material, iron-based or non-ferrous amorphous magnetic alloy, and ferrite (soft ferrite). Among these exemplified materials, Sendust is preferable from the viewpoint of suppressing magnetism in the Z-axis direction from the one end 131 on the side of the magnetic sensor 12 .

As shown in FIG. 6, the soft magnetic layer 13b is preferably thinner than the hard magnetic layer 13a. By making the thickness Tb of the soft magnetic layer 13b smaller than the thickness Ta of the hard magnetic layer 13a, a magnetic path is easily formed in the soft magnetic layer 13b. The magnetism from the body layer 13a is easily guided to the other end 132 opposite to the magnetic sensor 12 side.

From the viewpoint of reducing the magnetic flux density from the one end 131 side of the hard magnetic layer 13a, the ratio Tb/Ta between the thickness Tb and the thickness Ta is preferably 1/100 or more and less than 1/1, and 1/10. 1/7 or more and less than 1/3 is more preferable.

From the same point of view, the thickness Tb of the soft magnetic layer 13b is preferably 0.05 mm or more and 1 mm or less, more preferably 0.1 mm or more and 0.5 mm or less, and even more preferably 0.15 mm or more and 0.3 mm or less. The thickness Ta of the hard magnetic layer 13a is preferably 0.1 mm or more and 5 mm or less, more preferably 0.3 mm or more and 3 mm or less, and even more preferably 0.5 mm or more and 2 mm or less.

Although FIG. 6 shows a mode in which the soft magnetic layer 13b is provided on a part of the magnet 13, the soft magnetic layer 13b may be separate from the magnet 13. For example, a soft magnetic body may be provided between magnet 11 and magnetic sensor 12 .

FIG. 7 is a cross-sectional view schematically showing the magnetism M generated by the magnetism generator 71 arranged on the outer side 22 of the tire 2 in the vicinity of the detection target portion 24 of the tread portion 23 of the tire 2 . The tire wear sensor 6 shown in FIG. Note that the magnetism M generated by the magnetism generator 71 is always a predetermined value. The predetermined value of the magnetic flux density of the magnetism M on the surface of the magnetism generator 71 can be, for example, 1 to 200 mT. It is preferable to

The magnetic sensor 12 detects the magnetism M generated by the magnetism generator 71 when the detection target portion 24 of the tread portion 23 of the tire 2 contacts the magnetism generator 71 positioned on the outer side 22 of the tire 2 . to measure the degree of wear of the tire 2.

The tire wear sensor 6 is attached to the inner side 21 of the tire 2 and includes a magnetic sensor 12 capable of detecting magnetism M. to measure Since the magnetism M emitted by the magnetism generator 71 is always a predetermined value, the magnetism M measured by the magnetic sensor 12 changes depending on the distance D between the magnetic sensor 12 and the magnetism generator 71 . Therefore, the distance D can be detected based on the magnetism M measured by the magnetic sensor 12 . Since the distance D changes as the tread portion 23 of the tire 2 wears, the tire wear sensor 6 can detect the degree of wear of the tire 2 based on the measured value of the magnetism M.

8A and 8B are a sectional view and a perspective view schematically showing a wear measurement system 70 comprising the tire wear sensor 6 and the magnetism generator 71. FIG. 8C is a plan view of the magnetism generator 71. FIG.
The wear degree measurement system 70 arranges the magnetism generator 71 so as to be in contact with the surface (tire surface) of the outer side 22 of the tire 2 in the detection target portion 24, moves the vicinity of the detection target portion 24, and moves the inner side of the detection target portion 24. The degree of wear of the tread portion 23 of the tire 2 is detected by detecting the magnetism from the magnetism generator 71 by the tire wear sensor 6 arranged at 21 .

As the amount of rubber decreases due to wear of the tread portion 23, the distance D (see FIG. 7) between the magnetic sensor 12 of the tire wear sensor 6 and the magnetism generator 71 decreases. The output from the tire wear sensor 6 increases in proportion to the square of the amount of decrease in the distance D due to wear of the tread portion 23 . Therefore, the degree of wear of the tire 2 can be detected based on the output of the tire wear sensor 6 .

As shown in FIG. 8C, the contact surface of the magnetism generator 71 that contacts the surface of the outer side 22 of the tire 2 may be configured by alternately arranging a plurality of pairs of different magnetic poles. When the magnetic sensor 12 of the tire wear sensor 6 is in contact with the tread portion 23 and the magnetism generator 71 is moved along the direction in which the magnetic poles are arranged as indicated by the double-headed arrow in FIG. The magnetism M (see FIG. 7) emitted by the magnetism generator 71 is detected. By moving the magnetism generator 71 along the direction in which the magnetic poles are arranged, the output from the magnetic sensor 12 changes. The degree of wear of the tread portion 23 can be measured by detecting the peak value of the magnetism M with the magnetic sensor 12 . For example, the thickness of the tread portion 23 is measured based on the maximum value of the output from the tire wear sensor 6 obtained when the magnetism generator 71 is moved. Note that, for example, a design indicating the arrangement position may be provided on the side surface of the tire 2 so that the position where the tire wear sensor 6 is arranged can be determined when viewed from the outside 22 of the tire 2 .

FIG. 9A is a perspective view showing a wear measurement system 72 according to a modification. 9B is a plan view schematically showing the structure of the magnetism generator 73. FIG. The wear degree measurement system 72 uses an electromagnet that generates magnetism at a contact point with the tire 2 , which is a contact object, as the magnetism generator 73 . By using an electromagnet as the magnetism generator 73, magnetic force can be generated only during measurement. Therefore, it is possible to prevent the magnetism generator 73 from attracting an iron nail or the like.

The length L of the magnetism generator 73 in the longitudinal direction is greater than or equal to the length R of the outer circumference of the tire 2 . Therefore, when the tire 2 is rolled in the circumferential direction in contact with the magnetism generator 73, by driving the electromagnet of the portion of the magnetism generator 73 that is in contact with the tire 2, manual intervention is not required. The degree of wear of the tire 2 can be measured without For example, the magnetism generator 73 is installed at the gate of the office, and when the truck 80 passes through the gate of the office, the tire 2 is passed over the magnetism generator 73 to measure the degree of wear of the tire 2. can.

The magnetic sensor 12 of the tire wear sensor 6 may include an acceleration sensor. By driving the electromagnet of the magnetism generator 71 when the acceleration sensor detects that the tire wear sensor 6 is positioned near the ground, the magnetism generator 73 can be operated efficiently.

FIG. 10 is a cross-sectional view schematically showing a wear measurement system 74 according to another modification. The wear measurement system 74 magnetizes the steel wire 25 embedded in the tire 2 with an electromagnet (magnetism generator) 75 and detects the magnetism emitted by the magnetized steel wire 25 . As shown in the figure, an electromagnet 75 is brought into contact with the surface of the outer side 22 of the tire 2 to magnetize the steel wire 25 embedded in the tire 2, and the magnetism emitted by the magnetized steel wire 25 is detected by the tire wear sensor 6. Thus, the degree of wear of the tire 2 can be detected. In this case, the magnetized steel wire 25 functions similarly to the magnetic generator 71 (see FIGS. 7, 8A and 8B).

If the magnetic field intensity of the electromagnet 75 is constant, the magnetization amount of the steel wire 25 changes according to the degree of wear of the tire 2 . Therefore, the degree of wear of the tire 2 can be detected by measuring the magnetization amount of the steel wire 25 with the tire wear sensor 6 . As shown in FIG. 10, since the steel wire 25 is provided along the entire circumference of the tire 2, the position where the steel wire 25 can be magnetized by the electromagnet 75 is the portion where the tire wear sensor 6 is provided. Not limited. That is, even if the portion where the tire wear sensor 6 is provided is in contact with the road surface when the vehicle stops, the measurement can be performed.

By magnetizing the steel wire 25 and using it, the degree of wear of the tire 2 can be measured using a small electromagnet 75 . Therefore, the device can be made smaller, and the degree of wear of the tire 2 can be measured using a handy type electromagnet 75 suitable for portability.

FIG. 11 is a diagram schematically showing an overall wear measuring system 90 that includes the tire wear sensor 1 and the magnetic body 3 and detects the wear of the tire 2 based on changes in magnetism. Although the tire wear sensor 1 is shown in FIG. Note that when the tire wear sensor 6 is used,

magnetism generators

71 and 73 are used instead of the magnetic body 3 .

The wear measurement system 90 detects the magnetism generated by the magnet 11 using the magnetic sensor 12 of the tire wear sensor 1 when the detection target portion 24 (see FIG. 2A) of the tread portion 23 of the tire 2 contacts the magnetic body 3. It detects and measures the degree of wear of the tire 2 .

By setting the length L of the magnetic body 3 in the longitudinal direction to be equal to or greater than the length R of the outer circumference of the tire 2, when the tire 2 of the truck 80 passes over the magnetic body 3 installed at a side gate or the like, it can be reliably carried out. First, the detection target portion 24 of the tread portion 23 of the tire 2 can be brought into contact with the magnetic body 3 . Therefore, the management device (wear evaluation device) 100 can manage the wear of the tire 2 using the wear of the tire 2 measured and output by the tire wear sensor 1 at the time of contact.

Therefore, in an industry that uses the track 80 or the like, in which it is important to manage the wear of the tire 2, by arranging the magnetic body 3 at the side gate of a sales office or business office, changes in the degree of wear on a daily basis can be automatically monitored. It is also possible to reliably confirm that the tire needs to be changed, and to notify the management device 100 or the smart phone of the driver that the tire needs to be replaced. Further, for example, a replacement tire 2 can be ordered from the management device 100 to the tire company 110 via a wide area communication network 120 such as the Internet.

12A is a functional block diagram showing the configuration of the tire wear sensor 1. FIG. As shown in the figure, the tire wear sensor 1 includes a measurement unit 14, a device ID storage unit 15, an acceleration sensor 16, a wear level output unit 17, and a communication unit 18.

The measurement unit 14 measures the degree of tire wear, and includes the magnet 11 and the magnetic sensor 12 described above. The device ID storage unit 15 is means for storing a device ID unique to the tire wear sensor 1, and is configured by a general-purpose memory or the like. The acceleration sensor 16 measures the acceleration applied to the tire wear sensor 1 as the tire 2 rotates, and detects grounding of the portion where the tire wear sensor 1 is provided based on changes in acceleration. The wear degree output unit 17 associates the measured wear degree of the tire 2 with the device ID, and outputs the result to an external device such as the management device 100 via the communication unit 18 . Therefore, the management device 100 and the like can acquire and manage the wear information in a state in which the individual tire 2 is associated with the wear information based on the device ID.

FIG. 12B is a functional block diagram showing the configuration of the management device 100. As shown in FIG. As shown in the figure, the management device 100 includes an ID information storage unit 101, a measured value acquisition unit 102, a threshold storage unit 103, a tire identification unit 104, and a communication unit 105. For example, a CPU and a storage device (RAM , ROM).

The ID information storage unit 101 associates and stores the device ID unique to the tire wear sensor and the tire to which the tire wear sensor is attached. The ID information storage unit 101 may store the device ID, the tire (degree of wear, attached wheel, etc.), and the type of truck or the like (vehicle type) to which the tire wear sensor is attached. The threshold storage unit 103 stores a threshold for the degree of tire wear, and the threshold may be set according to the type of vehicle such as a truck. Further, the threshold storage unit 103 may store a plurality of types of thresholds according to different degrees of tire wear.

The measured value acquisition unit 102 acquires the degree of tire wear associated with the device ID from the tire wear sensor 1 . Then, when the degree of wear of the tire exceeds the threshold, the tire identification unit 104 identifies the tire that needs to be replaced based on the device ID associated with the degree of wear of the tire and the information in the ID information storage unit 101. output. The tire identification unit 104 may notify a predetermined notification destination of the output via the communication unit 105 . Examples of predetermined notification destinations include a computer mounted on a vehicle such as a truck on which a tire that needs to be replaced is installed, a mobile terminal of the driver or manager of the vehicle, and a tire that orders a tire that needs to be replaced. The company 110 grade|etc., is mentioned.

The ID information storage unit 101 may store the type of vehicle, and the threshold storage unit 103 may store the threshold set according to the type of truck or the like. In this case, the tire identification unit 104 may identify the tire that needs to be replaced based on the information in the ID information storage unit 101 when the degree of wear of the tire exceeds a threshold corresponding to the type of vehicle. For example, according to vehicle safety standards, in the case of vehicles running on expressways, the depth of treads that require tire replacement differs depending on whether the vehicle is a passenger car, a small truck, or a large truck/bus. Therefore, by specifying the tire that needs to be replaced based on the type of vehicle and the threshold value set according to the type, the tire can be replaced at an appropriate timing based on the usage mode.

Note that FIG. 11 shows an example in which the management device 100 acquires the degree of tire wear via the wide area communication network 120 that may include the Internet. However, the aspect of acquiring the degree of tire wear is not limited to this. For example, the management device 100 may acquire the degree of tire wear directly from the tire wear sensor 1 or through an intra-network within the office.

FIG. 13 is a flow chart of the wear evaluation method of this embodiment. Each step will be described below.
In S1, the tire wear sensor associates a device ID unique to the tire wear sensor with tire information for specifying the tire to which the tire wear sensor is attached, and outputs the information. S1 may be performed at the same time as or before S2, which will be described later. Here, the "tire information" includes the vehicle on which the tire is mounted, the position of the tire, the type of the tire, and the like. The vehicle information includes information that can identify the vehicle, the vehicle type, and the like.

In S2, the management device acquires the device ID and the tire information output in association with each other from the tire wear sensor, associates them, and stores them in the ID information storage unit.

In S3, the tire wear sensor measures the degree of tire wear. A tire wear sensor may measure tire wear when a vehicle having tires passes over a magnetic material or a magnetic field generator. For example, if a magnetic body or a magnetic field generator is provided at the entrance (gate) of an office where vehicles enter and exit, the degree of tire wear can be measured when leaving (returning from) an office. As a result, even if the vehicle is a truck or the like on which cargo is loaded, the measurement can be performed without loading the cargo, so that the influence of the cargo can be eliminated and the detection accuracy of the degree of tire wear can be improved.

In S4, the tire wear sensor outputs the degree of wear of the tire measured in S3 in association with the device ID of the tire wear sensor that measured the degree of wear. The output may be made at the same time as the measurement of the degree of wear or at predetermined intervals after the measurement. When outputting after measurement, the tire wear sensor may output multiple degrees of wear as they are, or output them as an average value of multiple degrees of wear. By outputting as an average value, the influence of measurement error can be suppressed.

In S5, the management device acquires the degree of wear output in S4 and the tire threshold value stored in the threshold storage unit, compares the degree of wear with the threshold value, and determines whether the tire needs to be replaced. Tires that reach a threshold level of wear typically require replacement.

In S6, the management device acquires the device ID associated with the wear degree measurement value that has reached the threshold value, and based on the tire information stored in association with the device ID, the tire to which the measuring device is attached, i.e. A tire whose degree of wear has reached a threshold value is specified and output to a predetermined output destination. Here, the predetermined output destination includes a display device of a management device, a display device of a vehicle equipped with a tire requiring replacement, and the like.

According to the tire wear degree evaluation method described above, the wear degree measurement value and the tire can be associated on a one-to-one basis via the device ID of the tire wear sensor. Therefore, it is possible to measure the degree of wear of the tire and determine whether the tire needs to be replaced at different times and places. Therefore, instead of manipulating the tire wear sensor when the vehicle is stopped, the tire requiring replacement can be specified by the management device based on the measured value of the degree of wear output from the tire wear sensor.

As described above, the present invention can measure the degree of tire wear without embedding a magnet in the tire, so it is useful as a tire wear sensor with little risk of puncture caused by attracting iron nails or the like.

1, 4, 5, 6: tire wear sensor 2: tire 3: magnetic material 11: magnet 12: magnetic sensor 13: magnet 13a: hard magnetic layer 13b: soft magnetic layer 131: one end 132: other end 14: measurement Unit 15 : Equipment ID storage unit 16 : Acceleration sensor 17 : Wear level output unit 18 : Communication unit 21 : Inside 22 : Outside 23 : Tread portion 24 : Detection target portion 25 :

Steel wires

42, 42A, 42B:

Magnetic sensor

51, 51A, 51B:

Magnets

52, 52A, 52B: Magnetic sensor 53: Bottom surfaces 70, 72, 74, 90:

Abrasion measurement systems

71, 73, 75: Magnetic generator 80: Truck (vehicle)
100: Management device (wear degree evaluation device)
101: ID information storage unit 102: Measured value acquisition unit 103: Threshold storage unit 104: Tire identification unit 105: Communication unit 110: Tire company 120: Wide area communication network B: Reference point D: Distance M: Magnetism O: Rotation center S : Regions Ta, Tb : Thickness P : Straight lines L, R : Length

Claims

A tire wear sensor located inside the tire that detects the degree of wear of the tire based on changes in magnetism,
a magnet positioned inside the tire;
a magnetic sensor arranged closer to the center of rotation of the tire than the magnet and capable of detecting magnetism emitted by the magnet;
The wear degree of the tire is measured by detecting the magnetism generated by the magnet by the magnetic sensor when the detection target portion of the tread portion of the tire comes into contact with a magnetic material positioned outside the tire. and a tire wear sensor.
Having two magnetic sensors,
The two magnetic sensors are arranged at point-symmetrical positions with respect to the magnet when viewed along the radial direction of the tire from the rotation center side,
A tire wear sensor according to claim 1.
Having two each of the magnetic sensors and the magnets,
The two magnetic sensors and the two magnets are arranged at positions symmetrical with respect to a reference point when viewed along the radial direction of the tire from the rotation center side,
wherein the magnetic sensor and the magnet are arranged on the same straight line passing through the reference point;
A tire wear sensor according to claim 1.
The magnetic sensor is arranged at a position farther from the reference point than the magnet,
A tire wear sensor according to claim 3.
The magnet has a soft magnetic layer made of a soft magnetic material on one end side in the magnetization direction,
The one end side in the magnetization direction is arranged to be closer to the center of the tire than the other end side,
A tire wear sensor according to claim 1.
A tire wear sensor located inside the tire that detects the degree of wear of the tire based on changes in magnetism,
Having a magnetic sensor located inside the tire,
The magnetic sensor detects the magnetism emitted by the magnetism generator when the detection target portion of the tread portion of the tire comes into contact with the magnetism generator that emits a predetermined magnetism located outside the tire. a tire wear sensor that measures the degree of wear of the tire.
The magnetism generator is configured by alternately arranging a plurality of pairs of different magnetic poles,
The magnetic sensor detects the magnetism emitted by the magnetism generator when the magnetism generator is moved along the direction in which the magnetic poles are arranged while the magnetism generator is in contact with the tread portion.
A tire wear sensor according to claim 6.
The magnetism generator is an electromagnet that generates magnetism at the contact point with the contact object,
The magnetic sensor detects magnetism emitted by the electromagnet when the tire is rolling in the circumferential direction of the tire while being in contact with the electromagnet.
A tire wear sensor according to claim 6.
The electromagnet magnetizes a wire embedded in the tire by contacting the surface of the tire,
The magnetic sensor detects magnetism emitted by the magnetized wire,
A tire wear sensor according to claim 8.
a device ID storage unit that stores a device ID unique to the tire wear sensor;
a wear degree output unit that outputs the measured wear degree of the tire and the device ID in association with each other;
The tire wear sensor according to any one of claims 1-9.
A wear measurement system comprising a tire wear sensor arranged inside the tire and a magnetic body arranged outside the tire for detecting the degree of wear of the tire based on changes in magnetism,
The tire wear sensor is
a magnet positioned inside the tire;
a magnetic sensor arranged closer to the center of rotation of the tire than the magnet and capable of detecting magnetism emitted by the magnet;
The wear of the tire, characterized in that when the detection target portion of the tread portion of the tire contacts the magnetic body, the magnetic sensor detects the magnetism emitted by the magnet to measure the degree of wear of the tire. Degree measurement system.
The length in the longitudinal direction of the magnetic body is greater than the length of the outer circumference of the tire,
The tire wear measurement system according to claim 11 .
an ID information storage unit that associates and stores the device ID of the tire wear sensor and the tire to which the tire wear sensor is attached;
a measurement value acquisition unit that acquires the degree of wear of the tire associated with the device ID;
a threshold storage unit that stores a threshold value of the degree of wear of the tire;
A tire that identifies the tire that needs to be replaced when the degree of wear of the tire exceeds the threshold based on the device ID associated with the degree of wear of the tire and information in the ID information storage unit. characterized by comprising a specific part,
Tire wear evaluation device.
The ID information storage unit stores the device ID, the tire, and the type of vehicle on which the tire wear sensor is mounted,
The threshold storage unit stores the threshold according to the type of the vehicle,
The tire identification unit identifies the tire that needs to be replaced based on the information in the ID information storage unit when the degree of wear of the tire exceeds the threshold value according to the type of the vehicle.
The tire wear evaluation device according to claim 13.
outputting in association with a device ID unique to the tire wear sensor and tire information capable of identifying the tire to which the tire wear sensor is attached;
The tire wear sensor measures the degree of wear of the tire,
A method for evaluating the degree of wear of a tire, wherein the measured degree of wear and the device ID of the tire wear sensor that measured the degree of wear are output in association with each other.
The tire wear sensor measures the degree of wear of the tire when the vehicle equipped with the tire passes over a magnetic body or a magnetic field generator.
The tire wear degree evaluation method according to claim 15.
Acquiring a device ID unique to a tire wear sensor and tire information capable of identifying a tire to which the tire wear sensor is attached, and storing the two in association with each other;
Obtaining the degree of wear of the tire, comparing the degree of wear with a threshold,
Acquiring the device ID associated with the degree of wear, and identifying the tire to which the tire wear sensor is attached based on the device ID and the tire information associated with the device ID. A tire wear evaluation method.