Tire and power supply system

Abstract

The tire includes a power receiving coil that receives an AC magnetic field from outside the tire and generates power. The power receiving coil is provided on a sidewall inner surface facing a tire cavity region of the tire in a sidewall portion between a tread portion and a bead portion, and generates AC power by receiving an AC magnetic field transmitted through the sidewall portion. The power receiving coil is a circular coil extending along the sidewall inner surface so as to surround a single circle in the tire circumferential direction. The ratio Ts / Tmin is 1.0-5.5, where Ts is the thickness of the sidewall portion at a position where the power receiving coil is provided on the sidewall inner surface, and Tmin is the minimum thickness of the sidewall portion in the tire radial direction.

Description

Technical Field

[0001] The present invention relates to a tire and a power supply system for supplying electric power to an electronic device installed on the tire. Background Art

[0002] A technology has been proposed to monitor the tire status by embedding electronic devices such as sensors in tires. For example, there can be listed: an internal pressure alarm system in which a pressure sensor and a transmitter are provided in the tire cavity area to monitor the air pressure of a pneumatic tire, and the pressure monitoring result obtained by the pressure sensor is wirelessly transmitted from the transmitter to a receiving device on the vehicle side; or an acceleration sensor is provided on the inner peripheral surface side of the tread portion in the tire cavity area, and the monitoring result of the deformation behavior of the tread portion when the tire rotates obtained by the acceleration sensor is wirelessly transmitted from the transmitter provided in the tire cavity area to a receiving device on the vehicle side.

[0003] In order to drive such sensors and transmitters, electric power is required, and this electric power can be supplied by, for example, a battery built into the transmitter. However, since the power capacity supplied by the battery is limited, the sensor and transmitter cannot be driven semi-permanently, and it is necessary to perform a complicated process of disassembling the pneumatic tire assembled with the wheel from the wheel to replace the exhausted battery in the tire cavity area.

[0004] To address this problem, there is known a tire having a built-in electric circuit capable of stably supplying electric power to the electric circuit and a technology providing a structure for supplying electric power to the tire (Patent Document 1).

[0005] In the above technology, a circuit driven by receiving electricity and a secondary coil connected to the circuit are provided on the automobile tire, and an inverter connected to the vehicle's power supply device and a primary coil arranged on the part of the vehicle body facing the tire and excited by the inverter are provided on the vehicle body.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2000-255229 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In the above-mentioned technology, a plurality of secondary coils provided in the tire cavity region are buried in a manner adjacent to each other over the entire inner peripheral surface of the tire sidewall (see Patent Document 1). Figure 5 ).

[0011] In the above technology, the transmission efficiency is the highest when the secondary coils are located opposite to the primary coils. In addition, as the tire rotates, the relative positions of the primary coils and the secondary coils change, and the transmission power also changes. Therefore, depending on the relative rotational position of the tires with respect to the primary coils when the vehicle is stopped or running at a low speed, the transmission power may become low, and sufficient power may not be supplied to the transmitter and sensor.

[0012] An object of the present invention is to provide a tire capable of suppressing fluctuations in power transmission when power is supplied to an electronic device installed in a tire and improving transmission efficiency, and a power supply system used for the tire.

[0013] Technical means of solving problems

[0014] The present invention includes the following aspects.

[0015] Form[1]

[0016] A tire characterized by comprising a power receiving coil for generating electric power by receiving an alternating magnetic field from outside the tire, and

[0017] The invention comprises a power receiving coil provided on the inner surface of the sidewall of the tire between the tread portion and the bead portion and facing the tire cavity area of ​​the tire, and generates AC power by receiving the AC magnetic field transmitted through the sidewall portion.

[0018] The power receiving coil is a circular coil extending along the inner surface of the sidewall so as to circle around the tire circumference.

[0019] When the thickness of the sidewall portion at the position where the power receiving coil is provided on the sidewall inner surface is Ts [mm] and the minimum thickness of the sidewall portion in the tire radial direction is Tmin [mm], the ratio Ts / Tmin is 1.0 to 5.5.

[0020] Form[2]

[0021] The tire according to aspect [1], wherein, when the power receiving coil is referred to as a first power receiving coil, the tire further comprises a second power receiving coil, the second power receiving coil being provided on the inner surface of the sidewall and generating an AC magnetic field by receiving an AC magnetic field transmitted through the sidewall portion.

[0022] The second power receiving coil is a circular coil extending along the inner surface of the sidewall so as to be concentric with the first power receiving coil and to make a circle in the tire circumferential direction.

[0023] Form[3]

[0024] The tire according to aspect [2], wherein the first power receiving coil and the second power receiving coil have a discontinuity, wherein the discontinuity is formed so that the power receiving coils are discontinuity in the tire circumferential direction by extending both ends of the first power receiving coil and the second power receiving coil in a manner deviating from the tire circumferential direction,

[0025] In the tire circumferential direction, an angle formed by the interrupted portion of the first power receiving coil and the interrupted portion of the second power receiving coil is 4 degrees or more.

[0026] Form[4]

[0027] A tire according to form [2] or [3], wherein the height of the bead portion along the tire radial direction based on the end portion on the inner side of the tire radial direction is, when the cross-sectional height of the tire is set to Sh [mm], the height of the position on the inner surface of the sidewall where the thickness of the sidewall portion is Tmin is set to Ht [mm], the height of the position on the inner surface of the sidewall where the first power receiving coil is provided is set to H1 [mm], the height of the position on the inner surface of the sidewall where the second power receiving coil is provided is set to H2 [mm], and the aspect ratio of the tire is set to P × 100 [%], satisfies

[0028] Ht-Sh×P / 4≤H1≤Ht+Sh×P / 4, and

[0029] At least one of Ht-Sh×P / 4≤H2≤Ht+Sh×P / 4.

[0030] Form[5]

[0031] A power supply system, characterized in that: it wirelessly transmits power from a power transmission unit to a power receiving unit provided on a tire, thereby supplying power to an electronic device connected to the power receiving unit, and

[0032] The power transmission unit includes a power transmission coil, the power transmission coil being provided at a base portion that does not rotate relative to the tire and generating an alternating magnetic field.

[0033] The power receiving unit includes a power receiving coil, the power receiving coil being provided on the inner surface of the sidewall of the tire between the tread and the bead of the tire and facing the tire cavity area of ​​the tire, and generating AC power by receiving the AC magnetic field generated from the power transmitting coil and transmitted through the sidewall.

[0034] The electronic device is driven by receiving the power supply converted from the AC power to DC power in the power receiving unit,

[0035] The power transmission coil is disposed on the base portion so as to be arranged on the side opposite to the power reception coil side with respect to the tire side portion.

[0036] The power receiving coil is a circular coil extending along the inner surface of the sidewall so as to circle around the tire circumference.

[0037] When the thickness of the sidewall portion at the tire radial position where the power receiving coil is provided on the sidewall inner surface is Ts [mm] and the minimum thickness of the sidewall portion in the tire radial direction is Tmin [mm], the ratio Ts / Tmin is 1.0 to 5.5.

[0038] Form[6]

[0039] The power supply system according to aspect [5], wherein the power transmission coil has a planar power transmission area arranged toward the tire side portion.

[0040] The power transmission coil has an arc-shaped curvature portion extending at a predetermined curvature within a plane of the power transmission region.

[0041] The curvature portion forms a partial section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil when viewed in the tire width direction.

[0042] Form[7]

[0043] The power supply system according to aspect [6], wherein the power receiving coil has a discontinuity portion, the discontinuity portion being formed so as to discontinuity the power receiving coil in the tire circumferential direction by extending both ends of the power receiving coil in a manner deviating from the tire circumferential direction,

[0044] A ratio d / L of a distance d [mm] between both end portions of the discontinuity in the tire circumferential direction to a length L [mm] of the curvature portion along the tire circumferential direction is 1 / 3 or less.

[0045] Form[8]

[0046] The power supply system according to aspect [6] or [7], wherein, when the power receiving coil is referred to as a first power receiving coil, the power receiving unit further comprises a second power receiving coil, the second power receiving coil being provided on the inner surface of the tire sidewall and generating an AC magnetic field by receiving an AC magnetic field transmitted through the tire sidewall portion,

[0047] The second power receiving coil is a circular coil extending along the inner surface of the sidewall so as to be concentric with the first power receiving coil and to make a circle in the tire circumferential direction.

[0048] Form[9]

[0049] A power supply system according to form [8] or [9], wherein a ratio R / G of a distance R [mm] in the tire radial direction between the first power receiving coil and the second power receiving coil to an average value G [mm] of distances between the power transmission area and each of the first power receiving coil and the second power receiving coil is 0.1 to 1.2.

[0050] Form

[10]

[0051] A power supply system according to any one of forms [8] to

[10] , wherein, in a cross-section passing through the curvature portion along the radial direction of the tire, a first radial region and a second radial region where the curvature portion is located are not separated in the radial direction of the tire, and the second radial region has as its two ends the radial positions of the first power receiving coil and the second power receiving coil located on the side opposite to the curvature portion relative to the sidewall portion.

[0052] Form

[11]

[0053] A power supply system according to any one of forms [8] to

[10] , wherein the power transmission unit further includes a magnetic body, the magnetic body being arranged on the side opposite to the tire side relative to the power transmission coil, and having a relative magnetic permeability of 30 to 300 at the frequency of the AC magnetic field generated by the power transmission coil.

[0054] Form

[12]

[0055] The power supply system according to aspect

[11] , wherein the magnetic body is arranged on the side opposite to the tire side relative to the power transmission coil at a distance h [mm] from the power transmission coil,

[0056] A ratio h / G of the interval h to an average value G [mm] of distances between the power transmission area and each of the first power receiving coil and the second power receiving coil is 0.01 to 0.5.

[0057] Morphology

[13]

[0058] A power supply system according to any one of forms [8] to

[12] , wherein at least one of a ratio Ts1 / G1 of a thickness Ts1 [mm] of the sidewall portion at a position where the first power receiving coil is provided on the inner surface of the sidewall to a distance G1 [mm] between the power transmitting coil and the first power receiving coil in the tire width direction, and a ratio Ts2 / G2 of a thickness Ts2 [mm] of the sidewall portion at a position where the second power receiving coil is provided on the inner surface of the sidewall to a distance G2 [mm] between the power transmitting area and the second power receiving coil in the tire width direction is 0.1 to 0.7.

[0059] Morphology

[14]

[0060] The power supply system according to any one of aspects [5] to

[13] , wherein the power transmission coil and the power reception coil are each formed of a single wire.

[0061] The conductor diameter of the conductive wire in the power transmission coil is larger than the conductor diameter of the conductive wire in the power reception coil.

[0062] Morphology

[15]

[0063] A power supply system according to any one of forms [5] to

[14] , wherein, when viewed along the tire width direction, the power transmission coil is located within an angle range of 45 degrees on both sides of the tire circumference with respect to a line extending vertically upward from the rotation center axis of the tire.

[0064] Effects of the Invention

[0065] According to the tire and the power supply system described above, it is possible to suppress fluctuations in power when power is supplied to an electronic device provided in the tire, and to improve transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a diagram showing an example of a cross section of a tire and a power supply system according to an embodiment.

[0067] Figure 2 This is a diagram showing the power receiving coil from above.

[0068] Figure 3 It is a cross-sectional view for explaining the arrangement of the power receiving coil.

[0069] Figure 4 This is a diagram showing a power transmission coil from above.

[0070] Figure 5 (a) is a diagram showing the overlapping of the power transmission coil and the power reception coil viewed in the tire width direction, and (b) is a partial enlarged diagram of (a).

[0071] Figure 6 (a) is a diagram showing the overlap of the interrupted portions of the power transmission coil and the power reception coil as viewed in the tire width direction, and (b) is a partial enlarged diagram of (a).

[0072] Figure 7 This is a diagram for explaining the arrangement of a power transmission coil and a power reception coil.

[0073] Figure 8 It is a diagram for explaining the arrangement of two power receiving coils.

[0074] Fig. 9 (a) to (d) are cross-sectional views for explaining the positional relationship between the power transmission coil and the power reception coil along the tire radial direction.

[0075] Fig.10 This is a diagram for explaining a magnetic body.

[0076] Fig.11 It is a diagram for explaining the arrangement of a magnetic body, a power transmission coil, and a power reception coil.

[0077] Fig.12 This is a diagram showing an example of a cross section of a coil.

[0078] Fig.13 It is a cross-sectional view for explaining the relationship between the distance between the power transmission coil and the power reception coil and the thickness of the tire side portion.

[0079] Fig.14 This is a cross-sectional view for explaining the relationship between the height position of the power receiving coil and the aspect ratio of the tire.

[0080] Fig.15 A diagram illustrating the angular range around the rotation center axis of the tire in which the power transmission coil is arranged. DETAILED DESCRIPTION

[0081] Hereinafter, a tire according to an embodiment and a power supply system for supplying power to an electronic device disposed on the tire will be described with reference to the accompanying drawings. The tire of the present invention is preferably a pneumatic tire, and in the following description, a pneumatic tire is taken as an example. The gas filled in the cavity area surrounded by the pneumatic tire and the rim is not limited to air, but may also be an inert gas such as nitrogen or other gas.

[0082] Figure 1 It is a diagram showing an example of a cross section of a pneumatic tire and a power supply system including the pneumatic tire. Figure 1 The pneumatic tire (hereinafter also referred to as tire) 10 shown in the figure includes a pair of bead cores 12, a carcass ply 14, and a belt layer 16 as a frame portion. The tire 10 is assembled on a wheel 11 (see Figure 3 )superior. Figure 3 Detailed description is given of a part of the wheel 11 (rim bottom surface, rim flange).

[0083] The bead core 12 is an annular member formed by winding a steel bead wire into multiple layers along the tire circumferential direction. The bead portion B is formed by the bead core 12, the rim retainer rubber 46 arranged around the bead core 12, the carcass ply 14 and the inner liner rubber 48. There is one bead portion B on each side in the tire width direction.

[0084] The carcass ply 14 is a member composed of organic fiber cords formed into a toroidal shape by being wound and folded around each bead core 12. In the carcass ply 14, the organic fiber cords are arranged so as to extend in the tire radial direction or the tire width direction. Figure 1 The tire 10 is shown to be constructed from a single carcass ply 14, but may also be constructed from a plurality of carcass plies formed into a toroidal shape.

[0085] The belt layer 16 is provided on the tire radially outer side of the carcass ply 14 and is composed of steel belt cords. The belt layer 16 is composed of two laminated belts, and the steel cords are inclined in different directions relative to the tire circumferential direction to form a staggered layer.

[0086] Around these skeleton parts, a tread rubber 40, a sidewall rubber 42, a bead core rubber 44, a rim retainer rubber 46, and an inner lining rubber 48 are arranged. The tread portion T is formed by the tread rubber 40, and the belt layer 16, the carcass ply 14, and the inner lining rubber 48 stacked on the tread rubber 40. On the radially outer side of the bead core 12, the sidewall rubber 42, the bead core rubber 44, the rim retainer rubber 46, the carcass ply 14, and the inner lining rubber 48 are bent convexly outward in the tire width direction. Figure 1 In the example shown, the sidewall portion S is a portion between the tread portion T and the bead portion B, and is formed by a sidewall rubber 42, a rim guard rubber 46, a carcass ply 14, and an inner liner rubber 48. The sidewall portion S is located between the tread portion T and the bead portion B, and has one on each side in the tire width direction. In addition, the structure of the rubber of the sidewall portion S is not limited to the above structure, and in addition to the sidewall rubber 42, the rim guard rubber 46, and the inner liner rubber 48, it may also include rubber such as auxiliary fillers, zero pressure liner, and bead core. The auxiliary filler is a rubber that reinforces the portion of the bead portion B side of the sidewall portion S, for example, a rubber that is sandwiched between the carcass ply and the rim guard rubber or the sidewall rubber and has a higher rubber hardness than the sidewall rubber. The zero pressure liner is a rubber that reinforces the sidewall portion of the zero pressure tire, for example, a rubber that is sandwiched between the carcass ply and the inner liner rubber and has a rubber hardness equal to or higher than the sidewall rubber.

[0087] The tire 10 further includes a power receiving unit 30 and an electronic device 24 .

[0088] The power receiving unit 30 receives power from the outside of the tire by wireless power transmission. The power receiving unit 30 includes a power receiving coil 18 .

[0089] The power receiving coil 18 is a part provided on the inner sidewall surface S1 of the tire 10 facing the cavity area C, and generates AC power corresponding to the AC magnetic field by receiving the AC magnetic field transmitted through the sidewall rubber 42, the carcass ply 14, and the inner lining rubber 48 of the sidewall portion S. Depending on the position of the power receiving coil 18, the AC magnetic field received by the power receiving coil 18 may sometimes also pass through the rim retaining rubber 46. In addition, depending on the structure of the rubber of the sidewall portion S, the AC magnetic field received by the power receiving coil 18 may sometimes also pass through other rubbers such as auxiliary fillers, zero-pressure liner, and bead core. The tire cavity area C is formed by the inner circumferential surface of the tire and the wheel 11 (in the Figure 3The following figures show a region surrounded by the bottom surface of the rim of a partial wheel and filled with air to a predetermined internal pressure. The power receiving coil 18 is a circular coil extending along the inner surface S1 of the sidewall so as to make a circle in the tire circumferential direction. Figure 2 The power receiving coil 18 in the illustrated example is a single-turn circular coil. Figure 2 This is a plan view of the power receiving coil 18. The power receiving coil 18 is provided on one of the pair of sidewalls S, which is arranged to face the vehicle side (vehicle inner side) to which the tire 10 is mounted via the wheel 11.

[0090] The power receiving unit 30 further includes a rectifier circuit and a voltage stabilizing circuit (not shown), and converts the AC power generated by the power receiving coil 18 into DC power to obtain power of a predetermined voltage.

[0091] The electronic device 24 includes a sensor unit 20 and a communication device 22. The sensor unit 20 includes a sensor element (not shown) that is driven by receiving a supply of DC power converted from AC power generated by the power receiving coil 18. The sensor element is not particularly limited, and is, for example, an acceleration sensor that measures the deformation behavior of the tread portion T of the rotating tire 10. The sensor unit 20 may further include an arithmetic processing circuit (not shown) that processes the measurement result data measured by the sensor element through arithmetic processing.

[0092] The communication device 22 is a part that transmits all data or processed information measured by the sensor unit 20 to a communication device (not shown) outside the tire by wire or wirelessly, and is driven by receiving a supply of DC power converted from the generated AC power.

[0093] A power line (not shown) extending from the power receiving unit 30 is connected to the sensor unit 20 or the communication device 22. The DC power from the power receiving unit 30 is used as driving power for the sensor unit 20 and the communication device 22 (power for signal processing, transmission, etc.).

[0094] The AC magnetic field received by the power receiving coil 18 is provided by, for example, Figure 1 The AC power supply device 102 and the power transmission unit 104 of the power transmission coil 100 shown in the figure generate power. The AC power supply device 102 can be supplied with power from a battery mounted on the vehicle body, or it can be supplied with power directly or via a rectifier regulator without going through a battery, such as regenerative power generated by an AC generator or a drive motor. The power transmission coil 100 is set on a base that does not rotate relative to the rotation of the tire 10, such as a non-rotating part of the suspension (such as a steering knuckle). A capacitor that forms a resonant circuit with the power transmission coil 100 is connected to the power transmission coil 100 and is arranged Figure 4The power transmission unit 104 generates AC power through an inverter provided in the AC power supply device 102 and generates an AC magnetic field M through the power transmission coil 100 .

[0095] According to one embodiment, power is transmitted from the power transmission unit 104 to the power reception unit 30 by a magnetic field resonance method. The magnetic field resonance method is to make the resonance frequency in the circuit of the power reception unit 30 coincide with the resonance frequency in the circuit of the power transmission unit 104, so that the AC magnetic field generated by the power transmission coil 100 causes the power reception coil 18 to resonate. That is, by resonance, an AC current flows through the power reception coil 18, and by rectifying the AC current, DC power can be obtained.

[0096] In the magnetic field resonance method, compared with the conventional electromagnetic induction method, the power transmission efficiency is high and the transmission distance is long. In view of this, it is preferable to make the resonance frequency of the power transmission unit 104 and the power receiving unit 30 consistent. The adjustment of the resonance frequency is performed, for example, by adjusting the inductance of the coils of the power transmission unit 104 and the power receiving unit 30 or the capacitance in the resonance circuit. On the other hand, the transmission efficiency is improved by shortening the transmission distance as much as possible, so the power receiving coil 18 is set in the tire side portion S as described above. As a result, the transmission distance between the power transmission coil 100 set on the non-rotating part of the suspension is shortened, so that a higher transmission efficiency can be obtained.

[0097] In addition, when using the magnetic field resonance method, if there is a conductive material such as metal near the power receiving coil 18, eddy current loss will be generated, reducing the transmission efficiency. Therefore, the power receiving coil 18 is preferably arranged on the sidewall portion S away from the conductive material (for example, the belt cord of the belt layer 16 and the bead wire of the bead core 12).

[0098] As described above, the power receiving coil 18 is a circular coil extending along the inner surface S1 of the sidewall in a manner of circumferentially extending around the tire. Therefore, the position and length of the circumferential portion of the power receiving coil 18 facing the power transmitting coil 100 will not substantially change due to the rotation of the tire 10, thereby suppressing the variation of the transmitted power. Therefore, even when the vehicle is stopped or running at a low speed, the amount of power supplied to the electronic device can be maintained constant. In this way, according to the power receiving coil 18, power can be supplied when the vehicle is running or stopped, or at any time regardless of the vehicle speed. The power receiving coil 18 is preferably formed in a circular shape with a constant curvature. In addition, the power receiving coil 18 is preferably arranged around the concentric circle of the sidewall portion S centered on the rotation center axis of the tire 10. Note that the tire circumferential direction refers to the circumferential direction of the tire rotation center axis. The position of the concentric circle of the sidewall portion S is determined without grounding the tire 10. As described above, the power receiving coil 18 is a ring-shaped coil that forms a closed area that contains the tire's rotation center axis on the inner circumference side, so the area of ​​the sidewall inner surface S1 occupied by the power receiving coil 18 in the tire radial direction is very small. Therefore, even if the power receiving coil 18 is set in a thinner portion of the sidewall portion S where the longitudinal deflection generated by the rotation of the tire 10 is large, it is difficult for it to be peeled off or fall off from the sidewall portion inner surface S1. On the other hand, in the case where a plurality of coils are arranged on the sidewall inner surface in a manner adjacent to each other in the tire circumferential direction, since the area of ​​the sidewall inner surface occupied by the coil in the tire radial direction is large, the amount of deformation of the coil due to the longitudinal deflection of the sidewall portion is also large, which easily causes the coil to be peeled off or fall off from the sidewall inner surface.

[0099] In the tire 10 of the present embodiment, the tire axial thickness of the sidewall portion S at the position where the power receiving coil 18 is provided on the sidewall inner surface S1 is set to Ts [mm] (refer to Figure 3 ), when the minimum thickness of the tire sidewall S in the tire axial direction across the tire radial direction is set to Tmin [mm], the ratio Ts / Tmin is 1.0 to 5.5. The tire axial direction refers to the direction parallel to the tire rotation center axis. The tire axial direction is parallel to the tire width direction. Figure 3 1 is a cross-sectional view for explaining the configuration of the power receiving coil 18. In this way, by providing the power receiving coil 18 in the thinner portion of the tire side portion S, the attenuation of the AC magnetic field passing through the tire side portion S can be suppressed to a minimum, thereby improving the transmission efficiency. In this way, according to this embodiment, the fluctuation of the transmitted power when supplying power to the electronic device can be suppressed, and the transmission efficiency can be improved. The ratio Ts / Tmin is preferably less than 4.0. When the power receiving coil 18 is provided at Figure 1 In the case of the position shown, the tire axial thickness Ts of the sidewall portion S is the total thickness of the sidewall rubber 42 , the carcass ply 14 , and the inner liner rubber 48 .

[0100] In addition, the rubber of the tire will generate heat due to driving. In addition, the power receiving coil may also generate heat due to wireless power supply. Therefore, if the power receiving coil is set at a position on the sidewall where the rubber generates more heat, it will hinder the release of the heat generated by the rubber, which may cause tire failure. In the tire 10 of this embodiment, as described above, since the power receiving coil 18 is set in the thinner portion of the sidewall S, the generated heat is easier to release than in the thicker portion of the sidewall S.

[0101] Furthermore, as described above, the thinner portion of the sidewall S is subjected to a greater amount of longitudinal deflection as the tire 10 rotates, and depending on the shape of the power receiving coil, it may be peeled off or fall off from the inner surface S1 of the sidewall. However, since the power receiving coil 18 is a circular coil, the amount of deformation caused by the deflection of the sidewall portion is smaller than that of a conventional power receiving coil having a power receiving area spanning the radial direction of the tire, and the durability of the power receiving coil 18 is improved.

[0102] Note that when the sidewall portion S is a portion that protrudes from the radially outer side of the rim toward the outer side in the tire width direction, and has a portion (rim protection portion) with a maximum tire axial thickness that is more than 1.5 times, and preferably more than 2 times, the minimum thickness Tmin of the sidewall portion S, the ratio Ts / Tmin is preferably in the range of 1.0 to 5.5, and more preferably 1.0 to 4.2. Figure 1 The sidewall portion S shown has a rim protection portion. When the sidewall portion S does not have a rim protection portion, the ratio Ts / Tmin is preferably in the range of 1.0 to 3.3, and more preferably in the range of 1.0 to 3.0. When the sidewall portion S has a zero pressure liner, regardless of the presence or absence of a rim protection portion, the ratio Ts / Tmin is preferably in the range of 1.0 to 1.8, and more preferably in the range of 1.0 to 1.5. Note that the two ends of the sidewall portion in the tire radial direction are, for example, the two ends of the sidewall rubber area in the tire radial direction, and the sidewall rubber area is exposed on the tire outer surface on the side of the sidewall portion opposite to the tire inner surface.

[0103] Furthermore, since the power receiving coil 18 is provided on the sidewall inner surface S1 of the sidewall portion S, heat generated by the generation of AC power can be easily released compared to a case where at least a portion thereof is buried in the sidewall portion S, which is preferred.

[0104] Note that the power receiving coil 18 can be fixed to the inner peripheral surface of the tire by, for example, bonding the coil to the inner peripheral surface of the tire using an adhesive or the like, or by a known fixing method to the inner surface S1 of the sidewall.

[0105] In the power supply system of one embodiment, power is wirelessly transmitted from power transmission unit 104 to power reception unit 30 provided on tire 10 attached to wheel 11, thereby supplying power to electronic device 24. The power supply system includes power transmission unit 104 and power reception unit 30.

[0106] The power transmission unit 104 includes a power transmission coil 100 that is provided in a non-rotating portion relative to the tire 10 and generates an AC magnetic field. The power transmission coil 100 is disposed on the side of the tire side S opposite to the power reception coil 18 side, specifically, on the outer side of the tire side S in the tire width direction.

[0107] The power receiving unit 30 is provided on the tire 10 .

[0108] Specifically, as described above, the power receiving unit 30 includes the power receiving coil 18, and the electronic device 24 includes the sensor unit 20 and the communication device 22. As described above, the power receiving coil 18 is provided on the inner sidewall surface S1 of the sidewall portion S facing the tire cavity region C of the tire 10, and the power receiving coil 18 receives the AC magnetic field generated from the power transmitting coil 100 and transmitted through the sidewall portion S to generate AC power.

[0109] In this power supply system, the power receiving coil 18 is a circular coil extending along the inner surface S1 of the sidewall so as to circle around the tire circumference. When the thickness of the sidewall portion S at the radial position of the tire where the power receiving coil 18 is provided on the inner surface S1 of the sidewall is set to Ts [mm], and the minimum thickness of the sidewall portion S across the radial direction of the tire is set to Tmin [mm], the ratio Ts / Tmin is 1.0 to 5.5, thereby being able to suppress fluctuations in transmitted power when supplying power to electronic devices and improve transmission efficiency.

[0110] The power transmission coil 100 is preferably disposed in an unsprung region of the suspension of the vehicle on which the tire 10 is mounted, at a position facing the sidewall portion S of the tire 10. By disposing the power transmission coil 100 in this manner, the power receiving coil 18 and the power transmission coil 100 can be disposed substantially facing each other, so that the power receiving coil 18 can efficiently receive the AC magnetic field.

[0111] For example, the power transmission coil 100 is preferably provided on a shock absorber housing in the case of a strut suspension, and is preferably provided on a steering knuckle in the case of a multi-link suspension.

[0112] According to one embodiment, one power transmission coil 100 is preferably provided for each tire 10. When a plurality of power transmission coils 100 are provided adjacent to each other, cross coupling occurs between adjacent power transmission coils 100, which tends to reduce power supply efficiency.

[0113] like Figure 4 As shown, the power transmission coil 100 preferably has a planar power transmission region disposed toward the tire side portion S. The power transmission region is a portion that generates an alternating current magnetic field. Figure 41 is a top view of the power transmission coil 100. The power transmission coil 100 is a coil formed by wiring an electric wire 100b in a spiral shape (vortex shape) on a non-magnetic substrate 100a. The electric wire 100b can be composed of a conductive material printed on the non-magnetic substrate 100a, or a steel wire-shaped conductor can be arranged to form a coil shape. The electric wire 100b wired in this way forms the power transmission area of ​​the power transmission coil 100. By setting the non-magnetic substrate 100a at the base, the power transmission coil 100 can move integrally with the tire 10 when turning.

[0114] like Figure 4 As shown, the power transmission coil 100 preferably has an arc-shaped curvature portion 101a extending at a predetermined curvature within the plane of the power transmission region. Figure 4 As shown in FIG. 1 , when viewed in the tire width direction, the curvature portion 101 a preferably forms a local section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil 18 . Figure 5 (a) is a diagram showing the overlapping of the power transmission coil 100 and the power reception coil 18 as viewed in the tire width direction. Figure 5 (b) Yes Figure 5 (a) is a partial enlarged view. Figure 5 (b) and the following references Figure 6 The power transmission coil 100 shown in (b) is a single-turn closed coil along the outline of the power transmission coil 100. By arranging the power transmission coil 100 relative to the power receiving coil 18 in this way, the longer circumferential portion of the power receiving coil 18 can receive the AC magnetic field from the power transmission coil 100, thereby improving the transmission efficiency. Figure 4 The curvature portion 101a in the example shown is a portion that forms an arc shape at the outermost portion along the tire radial direction in the power transmission area. By setting such a portion as the curvature portion 101a, it is easy to ensure that the length of the arc of the curvature portion 101a is long, and it is easy to ensure that the portion of the circumference of the power receiving coil 18 that receives the AC magnetic field from the power transmission coil 100 is long.

[0115] like Figure 2 , Figure 5 and Figure 6 As shown, the power receiving coil 18 has a discontinuity 18 a formed so that the power receiving coil 18 is discontinuous in the tire circumferential direction by extending both ends of the power receiving coil 18 in the circumferential direction away from the tire circumferential direction. Figure 6 (a) is a diagram showing the overlapping of the power transmission coil 100 and the interrupted portion 18a of the power reception coil 18 as viewed in the tire width direction. Figure 6 (b) Yes Figure 6 (a) is a partial enlarged view. A capacitor forming a resonance circuit together with the power receiving coil 18 is connected to the power lines at both ends of the power receiving coil 18 forming the interruption portion 18a. Figure 5and Figure 6 In the example shown, the capacitor is arranged in the rectangular area indicated by reference numeral 18b. The distance d [mm] between the two ends of the power receiving coil 18 in the interrupted portion 18a in the tire circumferential direction is equal to the length L [mm] of the curvature portion 101a of the power transmitting coil 100 in the tire circumferential direction (see Figure 4 , Figure 6 (b)) The ratio d / L is preferably 1 / 3 or less. By making the ratio d / L less than 1 / 3, when viewed in the tire width direction, even when the interruption portion 18a passes through the area of ​​the sidewall inner surface S1 overlapping the power transmission area of ​​the power transmission coil 100 as the tire 10 rotates, stable power transmission can be performed. In addition, when the tire 10 stops rotating, the area of ​​the AC magnetic field generated by the power transmission coil 100 passing through the interruption portion 18a becomes smaller, and the power supply can be maintained. The ratio d / L is preferably 1 / 4 or less. On the other hand, in order to prevent the transmission efficiency from being reduced due to the proximity effect, the two power lines constituting the interruption portion 18a are preferably not in contact with each other, and the ratio d / L is preferably 1 / 20 or more. In addition, from the perspective of balancing the amount of power transmitted and limiting the installation space for mounting the power transmission coil 100 on the base, the above-mentioned length L of the curvature portion 101a is preferably 50 to 180 mm.

[0116] When the power receiving coil 18 is referred to as the first power receiving coil 18, the power receiving unit 30 preferably further includes a second power receiving coil 28. The second power receiving coil 28 is provided on the inner surface S1 of the sidewall, and generates an AC magnetic field by receiving the AC magnetic field transmitted through the sidewall portion S. The second power receiving coil 28 is a circular coil extending along the inner surface S1 of the sidewall so as to be concentric with the first power receiving coil 18 and to go around the circumferential direction of the tire. The resonant frequency in the circuit of the second power receiving coil 28 coincides with the resonant frequency in the circuit of the power transmitting unit 104, and the AC magnetic field generated by the power transmitting coil 100 causes the second power receiving coil 28 to resonate. As described above, the resonant frequency in the circuit of the first power receiving coil 18 coincides with the resonant frequency in the circuit of the power transmitting coil 100, and as a result, also coincides with the resonant frequency in the circuit of the second power receiving coil 28, so that not only the AC magnetic field generated by the power transmitting coil 100 but also the AC magnetic field generated by the second power receiving coil 28 causes the first power receiving coil 18 to resonate. According to the research of the present inventors, it has been confirmed that by making the second power receiving coil 28 function as a relay coil in this way, a larger amount of AC power is generated in the first power receiving coil 18, thereby significantly improving the power supply efficiency. Note that the second power receiving coil 28 is different from the first power receiving coil 18 and does not have a power line connecting the second power receiving coil 28 to the communication device 22, but is independent of the communication device 22.

[0117] When the thickness of the sidewall portion S at the position where the second power receiving coil 28 is provided on the sidewall inner surface S1 is set to Ts2 [mm], the ratio Ts2 / Tmin is preferably 1.0 to 5.5. In this way, the attenuation of the AC magnetic field received by the second power receiving coil 28 through the sidewall portion S can be suppressed to a minimum, so that the first power receiving coil 18 can be strongly resonated. The preferred range of Ts2 / Tmin for each configuration of the rubber of the sidewall portion S is the same as the above-mentioned preferred range of the ratio Ts / Tmin for each configuration of the rubber of the sidewall portion S.

[0118] If the first power receiving coil 18 is arranged near the steel cord of the belt layer 16 and the bead core 12, eddy current loss will be generated due to the conductive material being located near the transmission path of the AC magnetic field, resulting in a decrease in transmission efficiency, which is not preferred. In particular, in a low-profile tire, since the interval between the belt layer 16 and the bead core 12 is narrow, the distance between the AC magnetic field and the conductive material becomes close, and the AC magnetic field may not reach the first power receiving coil 18 with sufficient strength. In such a tire, by using the second power receiving coil 28 together with the first power receiving coil 18, the AC magnetic field is relayed or amplified in the second power receiving coil 28, and the AC magnetic field that resonates the first power receiving coil 18 can be supplemented, thereby suppressing the decrease in transmission efficiency. Therefore, it is preferred that the power receiving coil closer to the steel cord of the belt layer 16 and the bead core 12 of the first power receiving coil 18 and the power receiving coil farther away be the second power receiving coil 28.

[0119] The distance R [mm] between the first power receiving coil 18 and the second power receiving coil 28 in the tire radial direction (see Figure 7 ) The average value (average distance) G [mm] of the distance (shortest distance) between the power transmission area of ​​the power transmission coil 100 and the first power reception coil 18 and the second power reception coil 28 (refer to Figure 7 ) The ratio R / G is preferably 0.1 to 1.2, more preferably 0.2 to 1.0. Figure 7: is a diagram for explaining the arrangement of the power transmission coil 100 and the power receiving coils 18 and 28. For efficient power transmission, the distance between the power transmission coil 100 and the power receiving coils 18 and 28 is preferably short. However, if the distance between the power transmission coil 100 and the power receiving coils 18 and 28 is short, the possibility of the sidewall S and the power transmission coil 100 coming into contact due to the lateral deformation of the sidewall S when the tire turns increases. On the other hand, in a low-profile tire, the degree of lateral deformation of the sidewall S when the tire turns is small, and the possibility of the sidewall S and the power transmission coil 100 coming into contact is low, but on the other hand, as described above, the transmission efficiency is easily reduced. Therefore, in a low-profile tire, from the viewpoint of suppressing the reduction in transmission efficiency, the radial interval R between the first power receiving coil 18 and the second power receiving coil 28 is preferably narrow. If the ratio R / G is within the above range, in tires of various aspect ratios, it is possible to avoid contact between the sidewall S and the power transmission coil 100 while suppressing the reduction in transmission efficiency. The average distance G is preferably 10 to 50 mm. If the average distance G is short, the possibility of the sidewall S contacting the power transmission coil 100 increases. On the other hand, if the average distance G is long, the transmission distance is too long, which tends to reduce the transmission efficiency.

[0120] The second power receiving coil 28 has a discontinuity 28a formed so that the second power receiving coil 28 is discontinuous in the tire circumferential direction by extending both ends of the second power receiving coil 28 in the circumferential direction of the tire. A capacitor forming a resonant circuit together with the second power receiving coil 28 is connected to the power lines at both ends of the second power receiving coil 28 forming the discontinuity 28a. Figure 8 As shown, in the tire circumferential direction (circumferential direction of the tire rotation center axis Ax), the angle formed by the interrupted portion 18a of the first power receiving coil 18 and the interrupted portion 28a of the second power receiving coil 28 is preferably 4 degrees or more. Figure 8 This is a cross-sectional view for explaining the arrangement of the two power receiving coils 18 and 28. The angle formed is the angle between the center positions of the interrupted portions 18a and 28a in the tire circumferential direction. If the angle formed by the interrupted portions 18a and 28a is less than 4 degrees, the power lines constituting the interrupted portions 18a and 28a may be too close, and the resonant circuit of one power receiving coil may be affected by the power lines of the other power receiving coil, resulting in loss. The angle formed is preferably 5 degrees or more.

[0121] like Fig. 9As shown, in the cross-section along the tire radial direction passing through the curvature portion 101a of the power transmitting coil 100 and the tire 10, it is preferred that the first radial region R1 and the second radial region R2 where the curvature portion 101a is located are not separated in the tire radial direction, and the second radial region R2 has the tire radial positions of the respective portions of the first power receiving coil 18 and the second power receiving coil 28 located on the opposite side of the curvature portion 101a relative to the sidewall portion S (facing the curvature portion 101a in a manner of sandwiching the sidewall portion S) as two ends. Fig. 9 (a) to (d) are cross-sectional views illustrating the positional relationship between the power transmission coil 100 and the power receiving coils 18, 28 along the tire radial direction. The first radial region R1 is a region in the tire radial direction with the outermost peripheral portion and the innermost peripheral portion in the tire radial direction of the electric wire 101b forming the curvature portion 101a as two ends. If the power transmission coil 100 and the power receiving coils 18, 28 are arranged in a manner that the two radial regions R1, R2 are not separated in the tire radial direction, the first power receiving coil 18 and the second power receiving coil 28 can receive the AC magnetic field generated by the power transmission coil 100 with sufficient strength, thereby increasing the effect of improving the transmission efficiency. Note that the two radial regions R1, R2 are determined when the tire 10 is mounted on the vehicle and filled with air to a specified internal pressure (the air pressure of the corresponding tire size specified for the vehicle. If not specified, it is 230 kPa). Fig. 9 (a) and Fig. 9 In the example shown in (b), the first radial region R1 and the second radial region R2 are connected in the tire radial direction. Fig. 9 (c) and Fig. 9 In the example shown in (d), the first radial region R1 and the second radial region R2 overlap in the tire circumferential direction. In order to receive the AC magnetic field generated by the power transmission coil 100 with sufficient strength in the power receiving coils 18 and 28, the effect of improving the transmission efficiency is increased. Fig. 9 (b) and Fig. 9 As in the example shown in (c), the first radial region R1 and the second radial region R2 preferably overlap in the tire circumferential direction.

[0122] like Fig.10 As shown, the power transmission unit 104 preferably further includes a magnetic body 110 disposed on the side opposite to the tire side S side with respect to the power transmission coil 100 . Fig.10 1 is a diagram for explaining the magnetic body 110. At the frequency of the AC magnetic field generated by the power transmission coil 100, the relative magnetic permeability of the magnetic body 110 is 30 to 300. Fig.10 The magnetic body 110 in the illustrated example is a magnetic sheet having a surface parallel to the surface of the power transmission region of the power transmission coil 100 . Fig.10The magnetic body 110 in the example shown is connected to the power transmission coil 100 and is laminated on the surface of the non-magnetic substrate 100a on the tire side S side. The thickness of the magnetic sheet is preferably 0.01 to 0.5 mm. The power transmission coil 100 is, for example, arranged in a wheel cover of a vehicle that accommodates a suspension, and a structural material or component containing a metal (conductor) such as aluminum or iron is arranged on the side opposite to the side on which the power receiving coils 18 and 28 are arranged relative to the power transmission coil 100 (the back side of the power transmission coil 100). Therefore, the alternating magnetic field generated by the power transmission coil 100 may cause eddy currents to be generated on the surface of the conductor, and the resulting loss may cause a decrease in transmission efficiency or cause heating of the metal parts. Therefore, it is preferred to configure the magnetic sheet to absorb or shield the magnetic flux generated by the power transmission coil 100. More preferably, as Fig.11 As shown, it is preferable to arrange the magnetic body 110 at a distance h [mm] from the power transmission coil 100. By providing the distance h, it is possible to suppress the magnetic saturation of the magnetic sheet and reduce the effect. Fig.11 1 is a diagram for explaining the arrangement of the magnetic body 110, the power transmission coil 100, and the power reception coils 18 and 28. Fig.11 In the example shown, the surface of the sidewall S side of the magnetic body 110 is laminated with a non-magnetic substrate 100a in contact with the power transmission coil 100. The distance between the power transmission coil 100 and the power receiving coils 18 and 28 is preferably short. Therefore, the ratio h / G of the interval h to the average value (average distance) G [mm] of the distances (shortest distance) between the power transmission area of ​​the power transmission coil 100 and the power receiving coils 18 and 28 is preferably 0.01 to 0.5.

[0123] The receiving coils 18, 28 and the transmitting coil 100 are preferably each composed of a single wire. Such coils are suitable for supplying power by magnetic field resonance using electromagnetic waves with a frequency in the MHz band. When supplying power by magnetic resonance, the frequency range is preferably in the range of 1MHz to 1GHz, and more preferably 2 to 20MHz. In addition, the receiving coils 18, 28 composed of a single wire can prevent the increase of AC resistance caused by the proximity effect compared to the receiving coils of the same cross-sectional area composed of power lines made of twisted pair wires.

[0124] The conductor diameter of the wire (single wire) in the power transmission coil 100 is preferably larger than the conductor diameter of the wire (single wire) in the power reception coils 18 and 28. Fig.12As shown, the conductor diameter D1 of the single wire is the length obtained by subtracting the thickness D2 of the coating layer covering the conductor from the diameter of the single wire. The conductor is made of, for example, copper, and the coating layer is made of, for example, resin. From the perspective of improving the transmission efficiency by generating a strong AC magnetic field and generating a large AC power, the larger the diameter of the power transmission coil 100 and the power receiving coil 18, 28, the more advantageous it is. However, if the diameter of the power receiving coil 18, 28 is too large, the strain during deformation due to the deformation of the tire side portion S will increase, which may lead to a decrease in durability. In addition, if the diameter of the power receiving coil 18, 28 is too large, it may be peeled off and fall off from the inner surface S1 of the tire side due to the centrifugal force during rotation. Therefore, by making the conductor diameter of the wire (single wire) in the power transmission coil 100 larger than the conductor diameter of the wire (single wire) in the power receiving coil 18, 28, the effect of improving the transmission efficiency that is suppressed due to the limitation of the thickness of the power receiving coil 18, 28 can be supplemented, and the durability of the power receiving coil 18, 28 can be ensured. The conductor diameter of the conducting wire (single wire) in the power receiving coils 18 and 28 is preferably 0.5 to 1.0 mm. The conductor diameter of the conducting wire (single wire) in the power transmitting coil 100 is preferably 0.8 to 1.5 mm. The number of turns of the power transmitting coil 100 is preferably 3 to 12 turns.

[0125] The thickness Ts1 [mm] of the sidewall portion S at the position where the first power receiving coil 18 is provided on the sidewall inner surface S1 (see Fig.13 ) relative to the distance (shortest distance) G1 [mm] between the power transmission coil 100 and the first power reception coil 18 in the tire width direction (refer to Fig.13 ) ratio Ts1 / G1, and the thickness Ts2 [mm] of the sidewall portion S at the position where the second power receiving coil 28 is provided on the sidewall inner surface S1 (refer to Fig.13 ) with respect to the distance (shortest distance) G2 [mm] between the power transmission coil 100 and the second power reception coil 28 in the tire width direction (refer to Fig.13 ) is preferably at least one of the ratios Ts2 / G2 of 0.1 to 0.7, and more preferably both of them are 0.1 to 0.7. Fig.13: is a cross-sectional view illustrating the relationship between the distance G1, G2 between the power transmission coil 100 and the power receiving coil 18, 28 and the thickness Ts1, Ts2 of the tire side portion S. As described above, in order to perform efficient power transmission, the distance between the power transmission coil 100 and the power receiving coil 18, 28 is preferably short. However, if the distance between the power transmission coil 100 and the power receiving coil 18, 28 is too short, the degree of lateral deformation of the tire side portion S becomes too large relative to the distance G1, G2, thereby increasing the fluctuation range of the transmitted power. In addition, if the distance between the power transmission coil 100 and the power receiving coil 18, 28 is too short, the possibility of the tire side portion S contacting the power transmission coil 100 due to the lateral deformation of the tire side portion S when the tire turns increases. By limiting at least one of the ratio Ts1 / G1 and the ratio Ts2 / G2 to the above range, it is possible to suppress the fluctuation of the transmission efficiency, avoid the contact between the tire side portion S and the power transmission coil 100, and perform power transmission efficiently. The ratio Ts1 / G1 and the ratio Ts2 / G2 are more preferably 0.2 to 0.6, and further preferably 0.15 to 0.55. The distance between the power transmission coil 100 and the power reception coils 18 and 28 can be adjusted by adjusting the thickness of a base for attaching the nonmagnetic substrate 100a or the magnetic body 110 to the base along the tire width direction.

[0126] like Fig.14 As shown, regarding the height of the bead portion B along the radial direction of the tire based on the inner end portion in the radial direction of the tire (the direction approaching or moving away from the rotation center axis Ax of the tire 10), when the cross-sectional height of the tire 10 is set to Sh [mm], the height of the position where the thickness of the sidewall portion S is Tmin on the sidewall inner surface S1 is set to Ht [mm], the height of the position where the first power receiving coil 18 is provided on the sidewall inner surface S1 is set to H1 [mm], the height of the position where the second power receiving coil 28 is provided on the sidewall inner surface S1 is set to H2 [mm], and the aspect ratio of the tire 10 is set to P × 100 [%], it is preferred to satisfy

[0127] Ht-Sh×P / 4≤H1≤Ht+Sh×P / 4, and

[0128] Ht-Sh×P / 4≤H2≤Ht+Sh×P / 4

[0129] At least one of the above, more preferably both of them are satisfied. Fig.14: is a diagram illustrating the relationship between the height position of the power receiving coils 18, 28 and the aspect ratio P. In a low-profile tire 10, the longitudinal deflection of the sidewall portion S is small, and the deformation of the power receiving coils 18, 28 caused by the rotation of the tire 10 can be suppressed, so that the durability of the power receiving coils 18, 28 can be easily ensured. On the other hand, in a low-profile tire 10, a reduction in transmission efficiency due to the steel cord of the belt layer 16 or the bead core 12 is likely to occur. Even if the ratio Ts1 / Tmin or the ratio Ts2 / Tmin at the position where the power receiving coils 18, 28 are provided satisfies the above range, it may be difficult to suppress the reduction in transmission efficiency. Therefore, the lower the tire, the closer the height position of the power receiving coils 18, 28 is preferably to the height position on the sidewall portion S where the thickness is Tmin. If the height position of the power receiving coils 18, 28 is set to satisfy at least one of the above two relationships, the balance between the durability of the power receiving coils 18, 28 and the suppression of the reduction in transmission efficiency is particularly excellent. The aspect ratio P is preferably 0.30 to 0.65.

[0130] In this specification, the various dimensions such as R, R2, Sh, Ht, H1, H2, etc. are measured in an unloaded state in which the rim of the tire 10 is assembled on a regular rim and filled with regular internal pressure. "Regular rim" refers to a rim specified for each tire in a specification system including the specifications based on which the tire is based, for example, a standard rim specified in JATMA, a "design rim" specified in TRA, or a "measuring rim" specified in ETRTO. However, when the tire 10 is a tire installed on a new car, the original wheel on which the tire 10 is assembled is used. The "normal internal pressure" refers to the air pressure specified for each tire in each specification system including the specifications to which the tire is based, and refers to the maximum air pressure specified in JATMA, the maximum value recorded in the table "Tire load limits at various cold inflation pressures" specified in TRA, and the "inflation pressure" specified in ETRTO. When the tire 10 is a passenger car tire, it is set to 230 kPa. However, when the tire 10 is a tire installed on a new vehicle, it is set to the vehicle-specified air pressure.

[0131] When viewed from the tire width direction (a direction parallel to the rotation center axis Ax of the tire 10), Fig.15 As shown, the power transmission coil 100 is preferably located within an angular range of 45 degrees on both sides (90 degrees in total) of a virtual line extending vertically upward from the rotation center axis Ax of the tire 10 in the tire circumferential direction. Fig.151 is a diagram illustrating the angle range in the tire circumferential direction (around the rotation center axis Ax of the tire 10) where the power transmission coil 100 is arranged. If the power transmission coil 100 is located near the ground contact surface of the tire 10, the height position of the power receiving coils 18 and 28 will change with the longitudinal bending deformation of the tire 10, and thus it is easy to shift relative to the height position of the power transmission coil 100. Therefore, the power receiving coils 18 and 28 cannot fully receive the AC magnetic field generated by the power transmission coil 100, which may lead to a decrease in transmission efficiency. If the power transmission coil 100 is arranged within the above-mentioned angle range, the influence of the change in the height position of the power receiving coils 18 and 28 caused by the longitudinal bending deformation of the tire 10 on the transmitted power can be reduced, thereby suppressing the decrease in transmission efficiency.

[0132] The tire and the power supply system of the present invention have been described in detail above, but the tire and the power supply system of the present invention are not limited to the above-described embodiments, and various improvements and changes may be made without departing from the gist of the present invention.

[0133] Description of Reference Numerals

[0134] 10: Tires

[0135] 11: Wheel

[0136] 12: Bead core

[0137] 12a: Bead bottom

[0138] 14: Carcass ply

[0139] 16: Belt

[0140] 18: Power receiving coil (first power receiving coil)

[0141] 18a: Interruption

[0142] 20: Sensor unit

[0143] 22: Communication device

[0144] 24: Electronic devices

[0145] 28: Power receiving coil (second power receiving coil)

[0146] 28a: Interruption

[0147] 30: Power receiving unit

[0148] 40: Tread rubber

[0149] 42: Sidewall rubber

[0150] 44: Bead core rubber

[0151] 46: Rim retainer rubber

[0152] 48: Lining rubber

[0153] 100: Power transmission coil

[0154] 100a: Non-magnetic substrate

[0155] 100b: Wire

[0156] 101a: Curvature

[0157] 102: AC power supply unit

[0158] 104: Power transmission unit

[0159] 110: Magnetic body

Claims

1. A tire, characterized in that: It has a power receiving coil that generates power by receiving an AC magnetic field from outside the tire, and The invention comprises a power receiving coil provided on the inner surface of the sidewall of the tire between the tread portion and the bead portion and facing the tire cavity area of ​​the tire, and generates AC power by receiving the AC magnetic field transmitted through the sidewall portion. The power receiving coil is a circular coil extending along the inner surface of the sidewall so as to circle around the tire circumference. When the thickness of the sidewall portion at the position where the power receiving coil is provided on the sidewall inner surface is defined as Ts and the minimum thickness of the sidewall portion in the tire radial direction is defined as Tmin, a ratio Ts / Tmin is 1.0 to 5.

5.

2. The tire according to claim 1, wherein: When the power receiving coil is referred to as a first power receiving coil, a second power receiving coil is further provided, the second power receiving coil is provided on the inner surface of the sidewall, and generates an AC magnetic field by receiving an AC magnetic field transmitted through the sidewall. The second power receiving coil is a circular coil extending along the inner surface of the sidewall so as to make a circle in the tire circumferential direction concentrically with the first power receiving coil.

3. The tire according to claim 2, wherein: The first power receiving coil and the second power receiving coil have a discontinuity portion, wherein the discontinuity portion is formed so that the power receiving coils are discontinuity in the tire circumferential direction by extending both ends of the first power receiving coil and the second power receiving coil in a manner deviating from the tire circumferential direction. In the tire circumferential direction, an angle formed by the interrupted portion of the first power receiving coil and the interrupted portion of the second power receiving coil is 4 degrees or more.

4. The tire according to claim 2 or 3, wherein: Regarding the height of the bead portion along the radial direction of the tire based on the end portion on the inner side of the tire radial direction, when the cross-sectional height of the tire is set to Sh, the height of the position where the thickness of the sidewall portion is Tmin on the inner surface of the sidewall is set to Ht, the height of the position where the first power receiving coil is provided on the inner surface of the sidewall is set to H1, the height of the position where the second power receiving coil is provided on the inner surface of the sidewall is set to H2, and the aspect ratio of the tire is set to P×100[%], it is satisfied Ht-Sh×P / 4≤H1≤Ht+Sh×P / 4, and At least one of Ht-Sh×P / 4≤H2≤Ht+Sh×P / 4.

5. A power supply system, characterized in that: The power transmission unit wirelessly transmits power to the power receiving unit provided on the tire, thereby supplying power to the electronic device connected to the power receiving unit. The power transmission unit includes a power transmission coil, the power transmission coil being provided at a base portion that does not rotate relative to the tire and generating an alternating magnetic field. The power receiving unit includes a power receiving coil, the power receiving coil being provided on the inner surface of the sidewall of the tire between the tread and the bead of the tire and facing the tire cavity area of ​​the tire, and generating AC power by receiving the AC magnetic field generated from the power transmitting coil and transmitted through the sidewall. The electronic device is driven by receiving the power supply converted from the AC power to DC power in the power receiving unit, The power transmission coil is disposed on the base portion so as to be arranged on the side opposite to the power reception coil side with respect to the tire side portion. The power receiving coil is a circular coil extending along the inner surface of the sidewall so as to circle around the tire circumference. When the thickness of the sidewall portion at the tire radial position where the power receiving coil is provided on the sidewall inner surface is Ts and the minimum thickness of the sidewall portion in the tire radial direction is Tmin, the ratio Ts / Tmin is 1.0 to 5.

5.

6. The power supply system according to claim 5, wherein: The power transmission coil has a planar power transmission area disposed toward the tire side portion. The power transmission coil has an arc-shaped curvature portion extending at a predetermined curvature within a plane of the power transmission region. The curvature portion forms a partial section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil when viewed in the tire width direction.

7. The power supply system according to claim 6, wherein: The power receiving coil has a discontinuity portion formed so that the power receiving coil is discontinuous in the tire circumferential direction by extending both ends of the power receiving coil in a manner deviated from the tire circumferential direction. A ratio d / L of a distance d between the two end portions of the discontinuous portion in the tire circumferential direction to a length L of the curvature portion along the tire circumferential direction is 1 / 3 or less.

8. The power supply system according to claim 6 or 7, wherein: When the power receiving coil is referred to as a first power receiving coil, the power receiving unit further includes a second power receiving coil, which is provided on the inner surface of the sidewall and generates an AC magnetic field by receiving an AC magnetic field transmitted through the sidewall. The second power receiving coil is a circular coil extending along the inner surface of the sidewall so as to make a circle in the tire circumferential direction concentrically with the first power receiving coil.

9. The power supply system according to claim 8, wherein: A ratio R / G of a distance R between the first power receiving coil and the second power receiving coil in the tire radial direction to an average value G of distances between the power transmission area and each of the first power receiving coil and the second power receiving coil is 0.1 to 1.

2.

10. The power supply system according to claim 8, wherein: In a cross section passing through the curvature portion along the tire radial direction, a first radial region and a second radial region where the curvature portion is located are not separated in the tire radial direction, and the second radial region has the tire radial positions of the first power receiving coil and the second power receiving coil located on the side opposite to the curvature portion relative to the sidewall portion as two ends.

11. The power supply system according to claim 8, wherein: The power transmission unit further includes a magnetic body disposed on a side opposite to the tire side portion side with respect to the power transmission coil and having a relative magnetic permeability of 30 to 300 at a frequency of an alternating magnetic field generated by the power transmission coil.

12. The power supply system according to claim 11, wherein: The magnetic body is disposed on a side opposite to the tire side portion with respect to the power transmission coil at a distance h from the power transmission coil. A ratio h / G of the interval h to an average value G of distances between the power transmission area and each of the first power receiving coil and the second power receiving coil is 0.01 to 0.

5.

13. The power supply system according to claim 8, wherein: At least one of a ratio Ts1 / G1 of a thickness Ts1 of the sidewall portion at a position on the inner surface of the sidewall where the first power receiving coil is provided to a distance G1 between the power transmitting coil and the first power receiving coil in the tire width direction, and a ratio Ts2 / G2 of a thickness Ts2 of the sidewall portion at a position on the inner surface of the sidewall where the second power receiving coil is provided to a distance G2 between the power transmitting area and the second power receiving coil in the tire width direction is 0.1 to 0.

7.

14. The power supply system according to any one of claims 5 to 7, wherein: The power transmission coil and the power reception coil are each composed of a single wire. The conductor diameter of the conductive wire in the power transmission coil is larger than the conductor diameter of the conductive wire in the power reception coil.

15. The power supply system according to any one of claims 5 to 7, wherein: When viewed in the tire width direction, the power transmission coil is located within an angle range of 45 degrees on both sides of a line extending vertically upward from the rotation center axis of the tire in the tire circumferential direction.

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