Tire and Wear Detection Systems

Abstract

To improve accuracy of abrasion detection of a tire.SOLUTION: A tire 10 includes a first magnetic body 61 arranged on a position determined beforehand on a tread part 34, a magnetic sensor 63 arranged on the furthermore inner diameter side than the first magnetic body 61, and a second magnetic body 62 arranged closer to the magnetic sensor 63 than the first magnetic body 61. The direction of a magnetic line 61a generated from the first magnetic body 61 is different from the direction of a magnetic line 62a generated from the second magnetic body 62, on a position where the magnetic sensor 63 is arranged.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire and a wear detection system. [Background technology]

[0002] JP 2019-203831 A discloses a wear measurement technique for pneumatic tires. In the pneumatic tire disclosed therein, a magnetic body is contained in the tread portion. Furthermore, a magnetic sensor that detects the magnetic flux density of the magnetic field formed by the magnetic body is arranged at a radially contained position corresponding to the magnetic body. The magnetic body is formed by dispersing powder particles of a hard magnetic material in a polymer material and is magnetized in one direction. The magnetic body is contained in the tread portion so that the magnetization direction of the magnetic body coincides with the tire radial direction. According to such a pneumatic tire, it is said that the wear state of the tire can be grasped by measuring the strength of the magnetic field that changes due to wear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-203831 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a magnetic sensor that detects magnetic flux density has temperature dependency. In addition, the magnetic field also depends on temperature. Therefore, when the temperature changes, the output of the magnetic sensor changes. For this reason, it is necessary to perform temperature correction on the output of the magnetic sensor. If temperature correction is not performed appropriately, it is not possible to determine whether the magnetic flux density has decreased due to wear or due to a temperature change, and the degree of tire wear is misjudged. It is preferable to be able to more accurately measure the strength of the magnetic field that changes due to wear for a pneumatic tire having a magnetic body embedded in the tread portion. [Means for solving the problem]

[0005] The tire disclosed herein includes a tread portion having a ground contact surface that is continuous in the circumferential direction along the outer circumferential surface, a first magnetic body arranged at a predetermined position of the tread portion, a magnetic sensor arranged on the inner diameter side of the first magnetic body, and a second magnetic body arranged closer to the magnetic sensor than the first magnetic body. At the position where the magnetic sensor is arranged, the direction of the magnetic field lines generated by the first magnetic body and the direction of the magnetic field lines generated by the second magnetic body are different. According to the tire disclosed herein, when the tread portion wears, the first magnetic body wears. The more the first magnetic body wears, the smaller the magnetic flux density of the magnetic field lines generated from the first magnetic body becomes. In contrast, the magnetic flux density of the magnetic field lines generated from the second magnetic body does not change. Therefore, the degree of wear of the tire can be detected based on the magnetic field lines detected at the position where the magnetic sensor is arranged. In addition, the magnetic flux density of the magnetic field lines generated from the first magnetic body and the magnetic flux density of the magnetic field lines generated from the second magnetic body are similarly temperature-dependent when detected by the magnetic sensor. In this manner, by providing the second magnetic body in addition to the first magnetic body, the influence of disturbance factors such as temperature is reduced.

[0006] The wear detection system disclosed herein includes such a tire, a memory unit that stores the initial direction of the magnetic field lines detected by the magnetic sensor, and a wear acquisition unit that is configured to obtain the wear degree of the tread portion based on the direction of the magnetic field lines detected by the magnetic sensor and the initial direction of the magnetic field lines. The wear detection system disclosed herein makes it possible to grasp the degree to which the tread portion has worn from a new tire. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a tire 10. [Diagram 2] FIG. 2 is a schematic diagram showing the arrangement of the magnetic sensors 63. As shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram showing magnetic field lines detected at a position P1 where the magnetic sensor 63 is disposed. [Figure 4] FIG. 4 is a schematic diagram showing magnetic field lines detected at position P1 where magnetic sensor 63 is disposed. [Diagram 5] FIG. 5 is a schematic diagram showing a modified example of the tire 10. As shown in FIG. [Figure 6] FIG. 6 is a schematic diagram showing a modified example of the tire 10. As shown in FIG. [Figure 7] FIG. 7 is a schematic diagram showing a modified example of the tire 10. As shown in FIG. [Figure 8] FIG. 8 is a schematic diagram showing the sensor module 100. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The tire and wear detection system disclosed herein will be described below with reference to the drawings. The present invention is not limited to the following embodiments. Each drawing is drawn diagrammatically and does not necessarily reflect the actual object. For example, the dimensional relationships (length, width, thickness, etc.) in each drawing do not necessarily reflect the actual dimensional relationships. Furthermore, each drawing shows only an example and does not limit the present invention unless otherwise specified. Furthermore, the same reference numerals are appropriately assigned to members and parts that perform the same function, and duplicated explanations are omitted. In this specification, a notation such as "X to Y" indicating a numerical range means "X or more and Y or less" unless otherwise specified.

[0009] "Tire 10" Fig. 1 is a cross-sectional view of a tire 10. Fig. 1 shows a radial cross-section of the tire 10 mounted on a wheel rim 11. The tire 10 is a so-called pneumatic tire. As shown in Fig. 1, the tire 10 is mounted on the wheel rim 11 so as to cover the outer periphery of the wheel rim 11. Air is filled and retained in the space enclosed by the tire 10 and the wheel rim 11.

[0010] <10 Tire Parts> As shown in FIG. 1, the tire 10 includes a bead portion 31, a sidewall portion 32, a shoulder portion 33, and a tread portion .

[0011] The bead portion 31 is the portion that is combined with the wheel, is attached to the wheel rim 11 around the entire circumference, and is the portion that fixes the tire 10 to the wheel rim 11. The sidewall portion 32 is the portion along the radial direction on the side surface of the tire 10. The sidewall portion 32 is the portion that bends the most.

[0012] The tread portion 34 is a portion that directly contacts the road surface, is provided on the outer peripheral surface of the tire 10, and has a ground contact surface that is continuous in the circumferential direction along the outer peripheral surface. The tread portion 34 is a portion that gradually wears away due to friction with the road surface. The tread portion 34 has a required thickness, and has grooves 34a formed in a predetermined pattern. Such grooves 34a are also referred to as a tread pattern.

[0013] The tread portion 34 is provided with slip signs 35 at a plurality of predetermined locations in the circumferential direction. The slip signs 35 are raised portions at a predetermined height at the bottoms of the grooves 34a of the tread portion 34. When the wear of the tread portion 34 progresses and it is time to replace the tire 10, the raised portions appear in the grooves 34a of the tread portion 34. The slip signs 35 indicate the time to replace the tire 10, but do not directly indicate how much the grooves 34a of the tread portion 34 have worn down. The amount to which the grooves 34a of the tread portion 34 have worn down can be determined by actually measuring the depth of the grooves 34a.

[0014] The shoulder portion 33 is a portion that connects the sidewall portion 32 and the tread portion 34. The shoulder portion 33 has a role of dissipating heat from the tread portion 34 and inside the tire that is generated during running due to friction with the road surface.

[0015] <10 Structures of Tires> The tire 10 is a molded product of rubber 41. The rubber 41 contains tire cords called carcass 42, belt 43, bead wire 44, etc., which form the framework of the tire 10. The carcass 42 may be made of a resin cord made of a polymeric material such as polyester, nylon, rayon, etc. The belt 43 may be made of a steel wire made of bundled high carbon steel, etc. The bead wire 44 may be made of a steel wire made of bundled high carbon steel, etc. In this way, the tire cords such as the carcass 42, belt 43, bead wire 44, etc. are members that impart required mechanical strength to the tire 10. Each tire cord is made of a material having required mechanical strength.

[0016] The carcass 42 is a continuous cord layer inside the tread portion 34, the shoulder portions 33 on both sides of the tire 10, the sidewall portions 32, and the bead portions 31. The belt 43 is a cord layer arranged on the outer diameter side of the carcass 42 in the tread portion 34 and continuing in the circumferential direction. The bead wire 44 is a ring-shaped reinforcing member made by bundling steel wires and covering them with rubber. The bead wire 44 is arranged in each of the bead portions 31 on both sides of the tire 10. The end of the carcass 42 is folded back on the bead wire 44. The bead wire 44 holds the end of the carcass 42. The bead wire 44 serves to receive the tension applied to the carcass 42 and fix it to the rim. By incorporating the tire cord in this way, mechanical strength that can withstand loads, impacts, and filling air pressure is ensured. In addition, a rubber layer called an inner liner is formed on the inner circumferential surface of the tire 10 and inside the tire cord, ensuring airtightness. A rubber layer called an overlayer is formed on the inside of the tire cord, and a tread portion 34 is formed on the surface portion (outer portion) of the overlayer.

[0017] Here, a pneumatic tire having a so-called radial structure is exemplified, but the tire is not limited to a radial structure unless otherwise specified. The tire disclosed herein is capable of detecting wear of the tread portion as described above. The tire may have a tread portion having a circumferentially continuous ground contact surface along the outer circumferential surface. In this respect, the structure of the tire is not particularly specified. The tire may have a so-called bias structure. The tire may also be a tube tire having a tube. The tire may also be a retread tire in which only the tread portion 34 can be replaced.

[0018] <Wear measurement structure> As shown in FIG. 1, the tire 10 includes a first magnetic body 61, a second magnetic body 62, and a magnetic sensor 63.

[0019] <First magnetic body 61> The first magnetic body 61 is disposed at a predetermined position in the tread portion 34. In this embodiment, the first magnetic body 61 is embedded in a predetermined position in a convex portion of the tread portion 34. The first magnetic body 61 may be, for example, a powder (magnetic powder) made of a hard magnetic material dispersed in a polymer material. The dispersed magnetic powder may be magnetized in a predetermined direction.

[0020] The first magnetic body 61 may be provided in the tread portion 34 by, for example, the following method. A hole is formed in a predetermined position in the convex portion of the tread portion 34 to embed the first magnetic body 61. Separately, the first magnetic body 61 is molded in a shape that fits the hole, by dispersing powder (magnetic powder) made of a hard magnetic material in a polymer material. The molded first magnetic body 61 is magnetized in a predetermined direction. The magnetized first magnetic body 61 is then attached and adhered to the hole formed in the convex portion of the tread portion 34.

[0021] As another method of providing the first magnetic body 61 in the tread portion 34, for example, the first magnetic body 61 magnetized in a predetermined direction is prepared. The prepared first magnetic body 61 is molded to fit a hole formed in the convex portion of the tread portion 34. The molded first magnetic body 61 is attached and adhered to the hole formed in the convex portion of the tread portion 34. In this manner, magnetization may be performed before the first magnetic body 61 is embedded in the tread portion 34, or may be performed after the first magnetic body 61 is embedded in the tread portion 34. Although the method of providing the first magnetic body 61 in the tread portion 34 has been exemplified, it is not limited to the method exemplified here. Various methods and materials may be adopted for the magnetization method of the first magnetic body 61 and the material of the magnetic powder.

[0022] <Magnetic powder> For example, from the viewpoint of having a large coercive force after magnetization and not being easily demagnetized, preferred magnetic powders include alnico magnets whose main components are aluminum, nickel, cobalt, and iron, ferrite magnets whose main component is iron oxide, samarium magnets whose main components are samarium and iron, and magnetic powders for producing neodymium magnets whose main components are neodymium, iron, and boron.

[0023] Specific examples of alnico magnets include Al-Ni-Co-Fe-Cu, ferrite magnets include Fe2O3-SrO, samarium magnets include Sm-Co-Fe-Cu and Sm-Fe-N, and neodymium magnets include Nd-Fe-B-Dy, Nd-Fe-Nb-B, and Nd-Pr-Fe-Nb-B.

[0024] In addition, two or more of the above magnetic powders may be selected and used. For example, a ferrite-based magnetic powder can be mixed with a samarium-based magnetic powder, and a samarium-based magnetic powder can be mixed with a neodymium-based magnetic powder to form a samarium-ferrite-based magnetic material, and a samarium-neodymium-based magnetic material, respectively.

[0025] Considering dispersibility in the polymeric material when forming the first magnetic body 61 and wear resistance due to metal particles, the particle size of the magnetic powder is preferably 400 μm or less, and more preferably 250 μm or less.

[0026] <Polymer material used for first magnetic body 61> As the polymeric material used for the first magnetic body 61, from the viewpoint of fully exhibiting the characteristics as a tire, a resin material or rubber material capable of exhibiting elasticity in a cured state is preferable, and from the viewpoint of the magnetic body formed by dispersing magnetic powder wearing down in the same way as tread rubber to provide a stable ride comfort, a resin material or rubber material capable of exhibiting wear characteristics equivalent to those of the tread rubber composition after curing is preferable.

[0027] Among the above-mentioned polymeric materials, considering that the location where the first magnetic body 61 is provided is the tread portion, the polymeric material used for the first magnetic body 61 may be a rubber material having the same composition as the tread rubber composition used for the tread portion 34. For example, the first magnetic body 61 may be a rubber material having the same composition as the tread rubber composition used for the tread portion 34, with magnetic powder dispersed therein. Also, for example, a part of the filler in the composition of the tread rubber composition may be replaced with magnetic powder. The amount of magnetic powder in the first magnetic body 61 is preferably 10% by mass to 70% by mass, more preferably 30% by mass to 70% by mass, and further preferably 40% by mass to 70% by mass.

[0028] <Magneticity of the first magnetic body 61> From the viewpoint of being able to reliably measure the magnetic flux density of the magnetic body without being affected by geomagnetism, the first magnetic body 61 is preferably configured to have a magnetic flux density of 0.05 mT or more at the measurement position where the magnetic sensor 63 is disposed. Also, from the viewpoint of being able to measure the magnetic flux density of the first magnetic body 61 by the magnetic sensor 63 even under the influence of magnetization and attenuation due to a steel cord provided inside the tire, it is more preferable that the first magnetic body 61 is configured to have a magnetic flux density of 0.5 mT or more at the measurement position of the magnetic sensor 63. Taking such viewpoints into consideration, the first magnetic body 61 is preferably configured to have a magnetic flux density of 1 mT or more on the surface of the first magnetic body 61.

[0029] On the other hand, from the viewpoint of preventing the magnetic force of the first magnetic body 61 from adversely affecting other electronic devices mounted on the vehicle, the surface magnetic flux density of the magnetic body is preferably, for example, about 600 mT or less. From the viewpoint of preventing metal pieces such as nails that fall on the road surface from being attracted during road driving, the magnetic flux density of the first magnetic body 61 measured on the surface of the tread portion 34 is more preferably, for example, about 60 mT or less. The magnetic flux density of the first magnetic body 61 can be measured with a Tesla meter. For example, the surface magnetic flux density of the first magnetic body 61 may be a value measured by directly contacting a Tesla meter with the magnetized surface of the first magnetic body 61. To magnetize the first magnetic body 61, a known magnetizing device, for example, a capacitor type magnetizing power supply device, a magnetizing coil, a magnetizing yoke, etc., can be used.

[0030] <Magnetic Sensor 63> The magnetic sensor 63 is disposed on the inner diameter side of the first magnetic body 61. In this embodiment, the magnetic sensor 63 is disposed on the inner circumferential surface of the tire 10, on the inner diameter side of the portion where the first magnetic body 61 is embedded in the tread portion 34.

[0031] The magnetic sensor 63 may be a sensor that detects the direction of magnetic lines at the position where the magnetic sensor is disposed. The sensor element used in the magnetic sensor 63 may be a sensor element that can detect the direction and strength of a magnetic field. For example, a magneto resistive element (MR) such as an SMR element, an AMR element, a GMR element, or a TMR element may be used for such a sensor element. A Hall element may be used for the sensor element used in the magnetic sensor. A magnetic impedance element may be used for the sensor element used in the magnetic sensor. In addition to the sensor elements listed here, various sensor elements that can detect the strength of a magnetic field may be adopted for the magnetic sensor 63. The effective measurement range of the magnetic flux density in the magnetic sensor 63 may be, for example, 1 mT or more.

[0032] An SMR element is a semiconductor magneto resistive element (SMR). The SMR element is a sensor that utilizes the change in resistance caused by the Lorentz force.

[0033] The AMR element is an anisotropic magnetoresistive (AMR) element. The AMR element is composed of, for example, a silicon or glass substrate and a thin film of an alloy mainly composed of a ferromagnetic metal such as Ni or Fe formed on the substrate. The AMR element shows shape anisotropy by aligning domain walls (boundaries between magnetic domains) in the longitudinal direction through patterning. The AMR element has the property that when a current is passed through a ferromagnetic thin film metal and a magnetic field is applied perpendicular to the current direction, the resistance value decreases according to the strength of the magnetic field.

[0034] A GMR element is a giant magneto resistive element (GMR) that utilizes the giant magnetoresistance effect. A GMR element is a laminated film of a ferromagnetic material (pinned layer), a non-magnetic metal, and a ferromagnetic material (free layer). When the magnetization directions of the pinned layer and the free layer are antiparallel to each other, or when the magnetization directions of the pinned layer and the free layer are aligned, the degree of scattering of electrons changes, and the resistance value changes.

[0035] A TMR element is a tunnel magnetoresistance element (TMR: Tunnel Magneto Resistive). A TMR element is a laminated film of a ferromagnetic material (pinned layer) - insulator - ferromagnetic material (free layer), and when the magnetization directions of the pinned layer and free layer are antiparallel to each other, or when the magnetization directions of the pinned layer and free layer are aligned, the ratio of electrons passing through the insulator changes due to the tunnel effect, causing a change in resistance value.

[0036] A Hall element is an element that detects magnetism using the Hall effect. When a current is passed through a semiconductor thin film, the Hall element outputs a voltage according to the magnetic flux density and direction due to the Hall effect.

[0037] A magneto-impedance element (MI) is an element that detects an external magnetic field by utilizing the magneto-impedance effect.

[0038] The magnetic sensor 63 may include one sensor element or may include multiple sensor elements. For example, two or more sensor elements may be arranged in one sensor package constituting the magnetic sensor 63.

[0039] For example, when the sensitivity direction of the sensor element used in the magnetic sensor 63 has directivity, it is preferable that three sensor elements whose sensitivity directions are oriented in three orthogonal axis directions are included in one sensor package. This makes it possible to obtain the magnetic sensor 63 that can determine the magnitude and direction of the magnetic force density at the position where the magnetic sensor 63 is placed.

[0040] The magnetic sensor 63 may include a first sensor element and a second sensor element. The first sensor element may have a sensitivity direction oriented in accordance with the direction of the magnetic field lines of the first magnetic body 61 at the position where the magnetic sensor 63 is arranged. The second sensor element may have a sensitivity direction oriented in accordance with the direction of the magnetic field lines of the second magnetic body 62. In this case, the first sensor element can detect the magnitude of the magnetic flux density according to the direction of the magnetic field lines of the first magnetic body 61. The second sensor element can detect the magnitude of the magnetic flux density according to the direction of the magnetic field lines of the second magnetic body 62. The magnitude and direction of the magnetic field density at the position where the magnetic sensor 63 is arranged can be obtained from the magnitude of the magnetic flux density obtained by the first sensor element and the magnitude of the magnetic flux density obtained by the second sensor element.

[0041] In this way, a plurality of sensor elements may be incorporated in one sensor package constituting the magnetic sensor 63. Furthermore, the same type of element may be used for the sensor elements incorporated in one sensor package. Furthermore, different types of elements, such as a Hall element and a magnetoresistance element, may be combined for the sensor elements incorporated in one sensor package. Magnetic sensors with various functions are available on the market, and a magnetic sensor that performs an appropriate function may be appropriately adopted as the magnetic sensor 63.

[0042] <Second magnetic body 62> The second magnetic body 62 is disposed closer to the magnetic sensor 63 than the first magnetic body 61. In this embodiment, the second magnetic body 62 is overlapped with the magnetic sensor 63 on the radially inner side of the tire 10. A hard magnetic body that is magnetized in advance may be used for the second magnetic body 62. The second magnetic body 62 may be made of a hard magnetic body. The surface magnetic flux density of the second magnetic body 62 may be smaller than that of the first magnetic body 61.

[0043] In the tire 10, the direction of the magnetic field lines generated by the first magnetic body 61 and the direction of the magnetic field lines generated by the second magnetic body 62 are different at the position where the magnetic sensor 63 is arranged. FIG. 2 is a schematic diagram showing the arrangement of the magnetic sensor 63. FIG. 2 shows the arrangement of the magnetic sensor 63, the first magnetic body 61, and the second magnetic body 62. FIG. 2 also shows the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 at the position where the magnetic sensor 63 is arranged. In the embodiment shown in FIG. 2, the magnetic field lines 61a of the first magnetic body 61 are directed in the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged. The magnetic field lines 62a of the second magnetic body 62 are directed along a plane perpendicular to the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged. In this way, it is preferable that the magnetic field lines 62a of the second magnetic body 62 are oriented in a direction different from the magnetic field lines 61a of the first magnetic body 61 at the position where the magnetic sensor 63 is disposed.

[0044] The first magnetic body 61 is embedded in the tread portion 34. The first magnetic body 61 is magnetized in the thickness direction of the tread portion 34 so that the inner diameter side is the N pole and the outer diameter side (surface side) is the S pole. Therefore, the magnetic field lines 61a of the first magnetic body 61 are oriented in the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged. The second magnetic body 62 is arranged overlapping the inner diameter side of the magnetic sensor 63. And, it is magnetized so that one side is the N pole and the other side is the S pole along the width direction of the tire 10. As a result, the magnetic field lines 62a of the second magnetic body 62 are oriented along a level surface perpendicular to the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged. In this embodiment, the magnetic field lines 62a of the second magnetic body 62 are oriented in a direction along the width direction of the tire 10 at the position where the magnetic sensor 63 is arranged. That is, at the position where the magnetic sensor 63 is disposed, the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 are perpendicular to each other.

[0045] 3 and 4 are schematic diagrams showing magnetic lines of force detected at the position P1 where the magnetic sensor 63 is disposed. In each of Figs. 3 and 4, a first vector 71 corresponding to the direction of the magnetic lines of force 61a of the first magnetic body 61 and the magnitude of the magnetic flux density, and a second vector 72 corresponding to the direction of the magnetic lines of force 62a of the second magnetic body 62 and the magnitude of the magnetic flux density are extracted from the magnetic lines of force detected at the position P1 where the magnetic sensor 63 is disposed, and a composite vector 70 is shown. Fig. 3 shows the tire 10 (see Fig. 2) in a new state. Fig. 4 shows the state where the tread portion 34 (see Fig. 2) is worn.

[0046] The magnetic sensor 63 may be capable of detecting, for example, the magnitude and direction of the magnetic flux density at the position where the magnetic sensor 63 is arranged. If no other disturbances such as external magnetic fields are taken into consideration, the magnitude and direction of the magnetic flux density according to the resultant vector 70 is detected by the magnetic sensor 63. The magnetic sensor 63 may also include a first sensor element whose sensitivity direction is oriented in accordance with the direction of the magnetic field lines 61a of the first magnetic body 61, and a second sensor element whose sensitivity direction is oriented in accordance with the direction of the magnetic field lines 62a of the second magnetic body 62. In this case, the first vector 71 and the second vector 72 are detected, and the resultant vector 70 can be obtained by calculation. The direction of the magnetic field lines at the position where the magnetic sensor 63 is arranged can be obtained as, for example, an inclination θ with respect to a reference plane that is predetermined in the magnetic sensor 63. The inclination with respect to the reference plane may be adjusted in advance by initialization or calibration.

[0047] In the embodiment shown in FIG. 2, when the tread portion 34 wears, the first magnetic body 61 wears. As shown in FIG. 4, the more the first magnetic body 61 wears, the smaller the magnetic flux density of the magnetic field lines 61a emitted from the first magnetic body 61 becomes. Accordingly, the first vector 71 along the direction of the magnetic field lines 61a of the first magnetic body 61 becomes smaller. In contrast, the magnetic flux density of the magnetic field lines 62a emitted from the second magnetic body 62 does not change. Therefore, as the wear of the tire 10 progresses and the magnetic flux density of the magnetic field lines 61a emitted from the first magnetic body 61 becomes smaller, the effect of the first vector 71 on the resultant vector 70 becomes smaller and the effect of the second vector 72 becomes larger. Therefore, the direction of the resultant vector 70 approaches the second vector 72.

[0048] The tire 10 includes a first magnetic body 61 disposed at a predetermined position of the tread portion 34, a magnetic sensor 63 disposed radially inward from the first magnetic body 61, and a second magnetic body 62 disposed closer to the magnetic sensor 63 than the first magnetic body 61. At the position where the magnetic sensor 63 is disposed, the direction of the magnetic field lines 61a generated by the first magnetic body 61 and the direction of the magnetic field lines 62a generated by the second magnetic body 62 are different.

[0049] The output value of the sensor element used in the magnetic sensor 63 may have temperature dependency. The direction θ of the magnetic field lines at the position where the magnetic sensor 63 is arranged is due to the magnetic field generated by the first magnetic body 61 and the second magnetic body 62. In the case where the output value of the sensor element used in the magnetic sensor 63 may have temperature dependency, when the magnetic flux density of the magnetic field lines 61a emitted from the first magnetic body 61 decreases due to a change in temperature, the magnetic flux density of the magnetic field lines 62a emitted from the second magnetic body 62 also decreases similarly. Therefore, the direction θ of the magnetic field lines detected by the magnetic sensor 63 does not depend on temperature but depends on the degree of wear of the first magnetic body 61.

[0050] In this tire 10, the direction of the magnetic field lines 61a generated by the first magnetic body 61 and the direction of the magnetic field lines 62a generated by the second magnetic body 62 are different at the position where the magnetic sensor 63 is arranged. Therefore, the degree of wear of the first magnetic body 61, in other words, the degree of wear of the tread portion 34 can be detected based on the direction of the magnetic field lines detected at the position where the magnetic sensor 63 is arranged. From this viewpoint, it is preferable that the magnetic sensor 63 can at least detect the direction of the magnetic field lines at the position where the magnetic sensor 63 is arranged. According to the magnetic sensor 63, the direction of the magnetic field lines at the position where the magnetic sensor 63 is arranged is detected. Based on the direction of the detected magnetic field lines, the change in the magnetic field generated by the first magnetic body 61 and the second magnetic body 62 can be obtained, and further the degree of wear of the tread portion 34 can be detected. Even if the magnitude of the magnetic flux density detected by the magnetic sensor 63 is affected by temperature, there is a correlation between the direction of the magnetic field lines detected by the magnetic sensor 63 and the degree of wear of the tread portion 34. Therefore, the degree of wear of the tread portion 34 can be obtained based on the direction of the magnetic field lines detected by the magnetic sensor 63. In this way, even if the magnitude of the magnetic flux density detected by the magnetic sensor 63 is affected by temperature, the degree of wear of the tread portion 34 can be obtained with high accuracy.

[0051] Also, tire cords such as the belt 43 may be magnetized. Even if tire cords such as the belt 43 are magnetized, the influence of the magnetic field lines emitted from the tire cords is constant at the position where the magnetic sensor 63 is disposed. The direction of the magnetic field lines detected by the magnetic sensor 63 is unlikely to change even due to the influence of the magnetic field lines emitted from the tire cords. Thus, according to this tire 10, the degree of wear of the first magnetic body 61 can be accurately determined by the magnetic sensor 63 without being easily influenced by disturbances such as magnetization of the tire cords.

[0052] FIG. 5 is a schematic diagram showing a modified example of the tire 10. In the embodiment shown in FIG. 5, the second magnetic body 62 is disposed beside the magnetic sensor 63 on the inner surface of the tire 10. The second magnetic body 62 has its N pole facing the magnetic sensor 63 and its S pole facing the opposite side to the magnetic sensor 63. In the embodiment shown in FIG. 5, the magnetic field lines 61a of the first magnetic body 61 are oriented in the thickness direction of the tire 10 at the position where the magnetic sensor 63 is disposed. The magnetic field lines 62a of the second magnetic body 62 are oriented along a plane perpendicular to the thickness direction of the tire 10. In this case, as shown in FIG. 5, the magnetic field lines 62a of the second magnetic body 62 are perpendicular to the magnetic field lines 61a of the first magnetic body 61. In this way, the arrangement and orientation of the second magnetic body 62 are not limited to the embodiment shown in FIG. 2 and can be appropriately changed.

[0053] FIG. 6 is a schematic diagram showing a modified example of the tire 10. In the embodiment shown in FIG. 6, the magnetic field lines 61a of the first magnetic body 61 are oriented along a plane perpendicular to the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged. In this embodiment, the N pole and S pole of the first magnetic body 61 are oriented in the width direction of the tire 10 in the tread portion 34 of the tire 10. In this case, the magnetic field lines 61a of the first magnetic body 61 are formed in a loop shape from the N pole to the S pole in the thickness direction of the tire 10, and are formed on the inner circumferential surface of the tire 10 in a direction generally along the inner circumferential surface of the tire 10. In contrast, the magnetic field lines 62a of the second magnetic body 62 are oriented in the thickness direction of the tire 10 at the position where the magnetic sensor 63 is arranged so as to overlap the magnetic sensor 63 in the thickness direction.

[0054] In this case, the first magnetic body 61 also wears in accordance with wear of the tire 10. Then, in accordance with wear of the tire 10, the magnetic flux density of the magnetic field lines 61a of the first magnetic body 61 observed at the position where the magnetic sensor 63 is disposed weakens. In contrast, the magnetic flux density of the magnetic field lines 62a of the second magnetic body 62 observed at the position where the magnetic sensor 63 is disposed does not change. Therefore, the direction of the magnetic flux density observed at the position where the magnetic sensor 63 is disposed changes in accordance with wear of the first magnetic body 61. Therefore, the degree of wear of the tire 10 can be detected based on the direction of the magnetic flux density detected by the magnetic sensor 63.

[0055] 6, the magnetic field lines 61a of the first magnetic body 61 may be oriented along a plane perpendicular to the thickness direction of the tire 10 at the position where the magnetic sensor 63 is disposed. The magnetic field lines 62a of the second magnetic body 62 may be oriented in the thickness direction of the tire 10. Here, the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 are substantially perpendicular to each other at the position where the magnetic sensor 63 is disposed. To realize such a configuration, the attitudes and orientations of the first magnetic body 61 and the second magnetic body 62 with respect to the magnetic sensor 63 are determined in advance.

[0056] FIG. 7 is a schematic diagram showing a modified example of the tire 10. As shown in FIG. 7, the first magnetic bodies 61 may be arranged at two positions slightly apart in the tread portion 34. In this case, one of the two first magnetic bodies 61 may have its N pole facing the inner diameter side in the thickness direction of the tread portion 34. The other first magnetic body 61 may have its S pole facing the inner diameter side. The magnetic sensor 63 may be arranged on the inner surface of the tire 10 between the two first magnetic bodies 61. The second magnetic body 62 may be overlapped with the magnetic sensor 63 on the inner diameter side of the tire 10, and its N pole may be facing the magnetic sensor 63. In this case, as shown in FIG. 7, at the position where the magnetic sensor 63 is arranged, the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 are approximately perpendicular to each other at the position where the magnetic sensor 63 is arranged. The direction of the magnetic flux density observed at the position where the magnetic sensor 63 is disposed changes according to the wear of the first magnetic body 61. Therefore, the degree of wear of the tire 10 can be detected based on the direction of the magnetic flux density detected by the magnetic sensor 63. In this manner, a plurality of first magnetic bodies 61 may be provided in the tread portion 34.

[0057] In the tire 10 disclosed herein, the direction of the magnetic field lines 61a generated by the first magnetic body 61 and the direction of the magnetic field lines 62a generated by the second magnetic body 62 are different at the position where the magnetic sensor 63 is disposed as described above. In the tire 10, the first magnetic body 61 disposed in the tread portion 34 is worn in accordance with the wear of the tread portion 34. In response to this, the magnetic flux density of the magnetic field lines 61a of the first magnetic body 61 is weakened. The weakening of the magnetic flux density of the magnetic field lines 61a of the first magnetic body 61 is evaluated relative to the magnetic flux density of the magnetic field lines 62a of the second magnetic body 62. Therefore, the degree of wear of the tire 10 can be detected based on the magnetic flux density observed at the position where the magnetic sensor 63 is disposed.

[0058] From this viewpoint, in the above-described embodiment, the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 are substantially perpendicular to each other at the position where the magnetic sensor 63 is disposed. In this case, when the magnetic flux density of the magnetic field lines 61a of the first magnetic body 61 is weakened, the change in the direction of the magnetic field lines observed at the position where the magnetic sensor 63 is disposed appears significantly. This makes it easier to evaluate the wear of the tread portion 34. However, as described above, it is preferable that the direction of the magnetic field lines 61a generated by the first magnetic body 61 and the direction of the magnetic field lines 62a generated by the second magnetic body 62 are different at the position where the magnetic sensor 63 is disposed. Unless otherwise specified, it is not limited that the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62 are perpendicular to each other at the position where the magnetic sensor 63 is disposed.

[0059] The magnetic sensor 63 may detect the magnetic flux density caused by both the magnetic field lines 61a of the first magnetic body 61 and the magnetic field lines 62a of the second magnetic body 62. From this viewpoint, the magnetic sensor 63 and the second magnetic body 62 may be provided on the inner side in the thickness direction of the tread portion 34 at the position where the first magnetic body 61 is provided. In addition, the magnetic flux density detected at the position where the magnetic sensor 63 is provided may be appropriately corrected for temperature.

[0060] FIG. 8 is a schematic diagram showing a sensor module 100. As shown in FIG. 8, the sensor module 100 includes a second magnetic body 62 and a magnetic sensor 63. In the embodiment shown in FIG. 8, the second magnetic body 62 and the magnetic sensor 63 may be incorporated into one sensor module. In the sensor module 100, for example, the second magnetic body 62 and the magnetic sensor 63 may be disposed at a predetermined position on one substrate 101. In this case, since the positional relationship between the magnetic sensor 63 and the second magnetic body 62 is determined, it is easy to predict the magnetic flux density of the magnetic field lines 62a of the second magnetic body 62 at the position where the magnetic sensor 63 is disposed.

[0061] As shown in FIG. 8, the tire 10 may include a power source 81 for supplying power to the magnetic sensor 63. The power source 81 may be, for example, a button battery. The tire 10 may also include a power generating element 82 for supplying power to the magnetic sensor 63. The power generating element 82 may have a performance sufficient to function as the power source 81 for supplying power to the magnetic sensor 63. A piezoelectric element, a vibration power generating element, an electromagnetic induction power generating element, a magnetostrictive power generating element, a friction charging element, or the like may be used as the power generating element 82. Kinetic energy such as vibration or inertial force obtained inside the tire may be used as the energy source for power generation. The tire may also include a storage element 83 for storing the electric energy generated by the power generating element 82.

[0062] The tire 10 may include a temperature sensor 84 as shown in FIG. 8. A thermostat IC including a sensor and a temperature detection circuit may be used as the temperature sensor 84. The temperature sensor 84 may have an operating temperature of, for example, about -40°C to 60°C. Various types of temperature sensors are commercially available, and any sensor having appropriate performance for attachment to the tire 10 may be used as the temperature sensor 84. The tire 10 may include a transmitting / receiving device 85 for outputting a signal from the magnetic sensor 63 to an external device as shown in FIG. 8. An appropriate wireless communication circuit may be used as the transmitting / receiving device 85.

[0063] The tire 10 may include a pressure sensor 86 and an acceleration sensor 87. For example, the pressure sensor 86 can be used to detect the pressure of the tire 10. The acceleration sensor 87 may be, for example, a sensor that detects acceleration. For example, the degree of wear of the tread portion 34 may be determined based on the detection result of the magnetic flux density obtained by the magnetic sensor 63 at an appropriate timing based on the acceleration sensor 87.

[0064] In the example shown in Fig. 8, the power generating element 82, the power storage element 83, the temperature sensor 84, the transmitting / receiving device 85, the pressure sensor 86, and the acceleration sensor 87 are mounted on one substrate 101 of the sensor module 100 on which the second magnetic body 62 and the magnetic sensor 63 are mounted. In this manner, the sensors to be mounted on the tire 10 may be mounted on one substrate 101. In this case, it is preferable that a mounting portion for mounting the sensor module 100 on the inner surface of the tire 10 is provided in advance. As a result, the sensor module 100 is configured to be mounted in a predetermined position on the inner surface of the tire 10 in a predetermined attitude. In this case, since the various sensors are gathered in the sensor module 100, it becomes easy to mount the sensor on the tire 10. Regardless of the form shown in FIG. 8, unless otherwise specified, the power generating element 82, the power storage element 83, the temperature sensor 84, the transmission / reception device 85, the pressure sensor 86, and the acceleration sensor 87, the second magnetic body 62, and the magnetic sensor 63 may each be provided in a separate sensor module 100.

[0065] The transmitting / receiving device 85 may be, for example, a transmitting / receiving device 201 that corresponds to the vehicle on which the tire 10 is mounted. Data obtained from various sensors may be sent to an electronic control circuit 202 (ECU) of the vehicle. The electronic control circuit 202 may be configured to record wear data of the tread portion 34 of the tire 10 on the vehicle.

[0066] The electronic control circuit 202 of the vehicle includes, for example, a storage unit 221 and a wear degree acquisition unit 222. The storage unit 221 stores the initial direction of the magnetic field lines detected by the magnetic sensor 63. The initial magnetic field lines are the direction of the magnetic field lines detected by the magnetic sensor 63 in a brand new tire 10 (see FIG. 1). For example, when the tire 10 is replaced with a new tire 10, the direction of the magnetic field lines detected by the magnetic sensor 63 may be stored in the storage unit 221. In addition, the wear degree acquisition unit 222 may be configured to obtain the wear degree of the tread portion 34 based on the direction of the magnetic field lines detected by the magnetic sensor 63 and the initial direction of the magnetic field lines. For example, as shown in FIG. 3 and FIG. 4, the direction of the magnetic field lines detected by the magnetic sensor 63 changes between the initial tire 10 and the tire 10 in which the wear of the tread portion 34 has progressed thereafter. The wear degree acquisition section 222 may be configured to determine the wear degree of the tread portion 34 based on the change in the direction of the magnetic field lines, for example.

[0067] Furthermore, as shown in FIG. 8, the wear data of the tread portion 34 of the tire 10 (see FIG. 1) may be configured to be recorded in the cloud server 302 through the communication network 300. In such a configuration, the wear data of the tread portion 34 of the tire 10 of the vehicle may be recorded in the cloud server 302. This allows the wear of the tire 10 of the vehicle to be recorded remotely. In this case, the cloud server 302 may be configured to notify the vehicle of the degree of wear of the tire 10, or to notify a vehicle with an advanced wear of the tire 10 of the time to replace the tire. The replacement time of tires of multiple vehicles can be managed collectively by the cloud server 302. In addition, when the tire 10 is a retread tire, the revival time of the tread portions of multiple tires of multiple vehicles can be managed collectively by the cloud server 302.

[0068] Although various explanations have been given above regarding the tire and wear detection system disclosed herein, the tire and wear detection system disclosed herein are not limited to the above-mentioned embodiments and modifications unless otherwise specified. Furthermore, the respective configurations of the various embodiments and modifications mentioned above can be appropriately combined as long as they are not mutually inhibiting. [Explanation of symbols]

[0069] 10 Tires 11 Wheel Rims 31 Bead section 32 Sidewall 33 Shoulder section 34 Tread section 34a groove 35 Slip Sign 41 Rubber 42 Carcass 43 Belt 44 Bead wire 61 First magnetic body 61a Magnetic field lines of the first magnetic body 61 62 Second magnetic body 62a: magnetic field lines of the second magnetic body 62 63 Magnetic Sensor 70 Composite Vector 71 First Vector 72 Second Vector 81 Power supply 82 Power generating element 83 Energy storage element 84 Temperature Sensor 85 Transmitting and Receiving Equipment 86 Pressure Sensor 87 Acceleration Sensor 100 Sensor Module 101 Substrate 201 Transmitting and receiving equipment 202 Electronic control circuit 221 Storage section 222 Wear degree acquisition unit 300 Communication Network 302 Cloud Server

Claims

1. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; A tire comprising: At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, A tire, wherein the magnetic field lines of the first magnetic body are directed along a plane perpendicular to a thickness direction of the tire at a position where the magnetic sensor is disposed.

2. The tire according to claim 1 , wherein the magnetic field lines of the second magnetic body are oriented in a thickness direction of the tire at a position where the magnetic sensor is disposed.

3. The tire according to claim 1 , wherein the magnetic sensor and the second magnetic body are provided on an inner side in a thickness direction of a tread portion at a position where the first magnetic body is provided.

4. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; Equipped with At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, The tire, wherein the magnetic sensor and the second magnetic body are provided on an inner side in a thickness direction of a tread portion at a position where the first magnetic body is provided.

5. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; A tire comprising: At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, The magnetic field lines of the first magnetic body are oriented in a thickness direction of the tire at a position where the magnetic sensor is disposed, and The magnetic field lines of the second magnetic body cross the magnetic sensor at a position where the magnetic sensor is disposed so as to be perpendicular to the thickness direction of the tire. tire.

6. the first magnetic body is embedded in a tread portion at a position where the magnetic sensor is disposed, The second magnetic body is disposed on the inner diameter side of the magnetic sensor.

6. The tire of claim 5.

7. the first magnetic body is embedded in a tread portion at a position where the magnetic sensor is disposed, The second magnetic body is disposed on the inner surface of the tire next to the magnetic sensor.

6. The tire of claim 5.

8. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; A tire comprising: At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, the first magnetic body is embedded in a tread portion at a position where the magnetic sensor is disposed, The N pole and the S pole of the first magnetic body are each oriented in a width direction of the tire in a tread portion of the tire, The second magnetic body is disposed so as to overlap with the magnetic sensor in the thickness direction of the tire, and the magnetic field lines of the second magnetic body are directed in the thickness direction of the tire. tire.

9. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; A tire comprising: At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, The first magnetic body is disposed at two positions slightly separated from each other in the tread portion, one of the two first magnetic bodies arranged at the two locations has an N pole oriented toward an inner diameter side in a thickness direction of the tread portion, and the other first magnetic body has an S pole oriented toward the inner diameter side, The magnetic sensor is disposed on an inner surface of the tire at a position where a magnetic field line connecting the two first magnetic bodies passes along the inner surface of the tire.

10. the second magnetic body is overlapped with the magnetic sensor on an inner diameter side of the tire, The magnetic field lines of the second magnetic body are oriented in the thickness direction of the tire.

10. The tire of claim 9.

11. a direction of a magnetic field line generated by the first magnetic body and a direction of a magnetic field line generated by the second magnetic body are perpendicular to each other at a position where the magnetic sensor is disposed; A tire according to any one of claims 1 to 10.

12. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; Equipped with a direction of a magnetic field line generated by the first magnetic body and a direction of a magnetic field line generated by the second magnetic body are perpendicular to each other at a position where the magnetic sensor is disposed; tire.

13. The tire according to claim 1 , wherein the magnetic sensor and the second magnetic body are arranged at predetermined positions on a single substrate.

14. A tread portion having a ground contact surface that is continuous in a circumferential direction along an outer peripheral surface; A first magnetic body disposed at a predetermined position of the tread portion; a magnetic sensor disposed radially inward of the first magnetic body; a second magnetic body disposed closer to the magnetic sensor than the first magnetic body; Equipped with At a position where the magnetic sensor is disposed, a direction of a magnetic field line generated by the first magnetic body is different from a direction of a magnetic field line generated by the second magnetic body, The tire, wherein the magnetic sensor and the second magnetic body are arranged at predetermined positions on a single substrate.

15. The tire according to claim 1 , wherein the magnetic sensor detects a direction of magnetic field lines at a position where the magnetic sensor is disposed.

16. The tire according to claim 1 , wherein the magnetic sensor is at least one of an SMR element, an AMR element, a GMR element, a TMR element, a Hall element, and a magnetic impedance element.

17. 17. A tyre according to any one of the preceding claims, comprising a power supply for supplying power to the magnetic sensor.

18. 18. A tire according to claim 1, comprising a power generating element for supplying power to the magnetic sensor.

19. 19. The tire according to claim 18, wherein the power generation element is any one of a piezoelectric element, a vibration power generation element, an electromagnetic induction power generation element, a magnetostrictive power generation element, and a frictional charging element, and is configured to generate power based on kinetic energy obtained inside the tire.

20. The tire according to claim 18 or 19, further comprising an electricity storage element that stores the electric energy generated by the power generation element.

21. 21. A tire according to any one of claims 1 to 20, further comprising a temperature sensor.

22. 22. A tire according to any one of claims 1 to 21, further comprising a transmitting / receiving device for outputting a signal of the magnetic sensor to an external device.

23. 23. A tire according to any one of the preceding claims, further comprising an acceleration sensor.

24. A tire according to any one of claims 1 to 23, a storage unit that stores the initial direction of the magnetic field lines detected by the magnetic sensor; a wear degree acquisition unit configured to acquire a wear degree of the tread portion based on a direction of the magnetic field lines detected by the magnetic sensor and the initial direction of the magnetic field lines; A wear detection system comprising:

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