Tire and wireless power supply system

Abstract

Provided are: a tire capable of suppressing decrease in power supply efficiency even on wet road surfaces; and a wireless power supply system utilizing the tire. A tire 10 includes: a tread section D that includes a tread surface 34; a pair of bead sections A; and a pair of sidewall sections B disposed between the tread section D and the bead sections A. The tire 10 comprises a power reception coil 40 that receives power supplied via an alternating-current magnetic field from outside the tire 10. In a view of a tire meridian cross-section in a non-loaded state, the power reception coil 40 is disposed on the radially inner side of the tire relative to the outermost position OP where a first virtual line L1, forming an angle α of 15° with a tire equatorial plane CP, and a tire side surface contact.

Description

Tires and wireless power supply systems

[0001] The present invention relates to a tire and a wireless power supply system.

[0002] Conventionally, a wireless power receiving system has been disclosed that supplies power between a power transmitting coil buried near the road surface and a power receiving coil attached to the center line of the tire in the tire width direction of a wheel (for example, Patent Document 1, Figure 1).

[0003] Japanese Patent Application Laid-Open No. 2021-059302

[0004] In the wireless power receiving system of Patent Document 1, when water adheres to the tire, for example during rainy weather, the water on the tire may block the magnetic field from the power transmitting coil reaching the power receiving coil installed in the tire, which may result in a decrease in power supply efficiency.

[0005] Furthermore, in the wireless power receiving system of Patent Document 1, the power receiving coil is usually attached to a metal rim, which tends to affect the AC magnetic field and reduce the power that the power receiving coil can receive. On the other hand, if the power receiving coil is placed away from the metal rim, the power supply efficiency improves, but it becomes difficult to dissipate the heat generated by the power receiving coil.

[0006] Furthermore, the wireless power receiving system of Patent Document 1 discloses that steel cord can be used for the belt that constitutes the tire (

[0022] ). However, if steel cord is used for the belt, part of the magnetic field that would otherwise reach the power receiving coil from the power transmitting coil may be blocked by the belt, which may prevent excellent power supply efficiency from being achieved.

[0007] A first object of the present invention is to provide a tire that can suppress a decrease in power supply efficiency even on a wet road surface, and a wireless power supply system using the tire.

[0008] A second object of the present invention is to provide a tire and a wireless power supply system using the tire that can achieve excellent power supply efficiency, assuming that the receiving coil is installed in a location other than the rim, due to an excellent fixing manner of the receiving coil at the installation location.

[0009] A third object of the present invention is to provide a tire that is less likely to obstruct the magnetic field reaching the power receiving coil from the power transmitting coil and that can suppress a decrease in power supply efficiency, and a wireless power supply system using the tire.

[0010] According to the present invention, the following aspects 1 to 14 are provided as means for achieving the first object (first invention), the following aspects 15 to 19 are provided as means for achieving the second object (second invention), and the following aspects 20 to 32 are provided as means for achieving the third object (third invention). [Aspect 1] A tire having a tread portion having a tread surface, a pair of bead portions, and a pair of sidewall portions provided between the tread portion and the bead portions, the tire including a power receiving coil that receives power supplied by an AC magnetic field from outside the tire, wherein the power receiving coil is provided radially inward of an outermost position where a first imaginary line that forms an angle of 15° with the tire equatorial plane and a tire side surface meet in a meridian cross section of the tire in an unloaded state. [Aspect 2] The tire according to Aspect 1, wherein, when viewed in a meridian cross section of the tire in an unloaded state, the power receiving coil is provided radially outward from a position that is 15% of the tire radial length SH from the bead toe, where SH is the tire radial length from the bead toe to the tread surface. [Aspect 3] The tire according to Aspect 1, wherein the power receiving coil is provided on an inner surface of the tire opposite to the outer surface having the tread surface. [Aspect 4] The tire according to Aspect 1, wherein, in a power receiving vicinity region between an intersection of a second imaginary line that is inclined 30° radially inward in the tire direction from an inner end of the power receiving coil toward the outer side in the tire width direction, and the tire outer surface, and an intersection of a third imaginary line that is inclined 30° radially outward in the tire direction from an outer end of the power receiving coil toward the outer side in the tire width direction, and the tire outer surface, the height of the unevenness of the tire outer surface is 1 mm or less over 50% or more of the area of ​​the power receiving vicinity region. [Aspect 5] The tire according to Aspect 4, wherein a coating layer made of a component other than rubber is provided on the outer surface of the tire in the vicinity of the power-receiving portion. [Aspect 6] The tire according to Aspect 1, wherein the groove area ratio in the tread portion is 12% or more and 38% or less, and the groove area ratio in a region from the tire equatorial plane to the inner side where the tire is mounted on the vehicle is greater than the groove area ratio in a region from the tire equatorial plane to the outer side where the tire is mounted on the vehicle, the difference being 3.5 percentage points or more.[Aspect 7] The tire according to Aspect 1, wherein a length Aw between a pair of the outermost positions and a contact width Tw under a load of 80% of a normal load satisfy the following formula (1): Tw≦0.88×Aw (1) [Aspect 8] The tire according to any one of Aspects 1 to 6, in a state where the tire is mounted on a normal rim. [Aspect 9] A wireless power feed system that supplies AC power to a power transmitting coil that forms a resonant circuit with a capacitor and a coil, and transmits power to the power receiving coil that also forms a resonant circuit with a capacitor and a coil, the wireless power feed system including the tire according to Aspect 1 or 2. [Aspect 10] The wireless power feed system according to Aspect 9, wherein the power receiving coil is disposed on an inner side mounted on a vehicle. [Aspect 11] The wireless power feed system according to Aspect 10, wherein at least a portion of the power receiving coil is located within a power feed region that extends in a winding axis direction of the power transmitting coil across both longitudinal end ends of the power transmitting coil in a tire meridian cross section. [Aspect 12] The wireless power feed system according to Aspect 10, wherein the power transmitting coil is installed within a range of 60° on both sides in the tire circumferential direction around an imaginary line extending vertically upward from the center of the tire. [Aspect 13] The wireless power feed system according to Aspect 10, wherein a power transmitting side surface of the power transmitting coil unit including the power transmitting coil that faces the power receiving coil has a contact angle of 50° or more. [Aspect 14] The wireless power feed system according to Aspect 10, wherein an angle of the power transmitting side surface of the power transmitting coil unit including the power transmitting coil that faces the power receiving coil with respect to the tire radial direction, as viewed from a tire meridian cross section, is within a range of 70° toward the side closer to the tire and 30° toward the side away from the tire, with the inner end of the power transmitting coil unit in the tire radial direction as the center.[Aspect 15] A tire having a bead core, a bead filler provided on the tire radially outer side of the bead core, a carcass folded around the bead core, and a belt provided on the tire radially outer side of the carcass, the tire having a power receiving coil on its inner cavity surface that receives power supplied by an AC magnetic field from outside the tire, wherein, in a tire meridian cross section, a deflection index Kv / P (= Gr (mm)) obtained by dividing the tire's vertical spring constant Kv (N / mm) by the tire's internal air pressure P (kPa), and a tire radial direction dimension CH (mm) from the tire's innermost position in the tire radial direction to the tire's outermost position in the tire radial direction satisfy 7≦CH / Gr≦95. [Aspect 16] The tire according to Aspect 15, wherein a tire radial direction dimension CH (mm) from an innermost position in the tire radial direction of the tire to an outermost position in the tire radial direction of the power receiving coil, a tire radial direction length SH (mm), and an aspect ratio r (0<r≦1) of the tire satisfy the following relationship: -0.1r+0.17≦CH / SH≦-0.3r+0.6. [Aspect 17] The tire according to Aspect 15 or 16, wherein a tire radial direction dimension DH from an outermost position in the tire radial direction of the power receiving coil to an innermost position in the tire radial direction of the belt, the tire radial direction region WH, and a sum [ΣGiHi] of products of thicknesses Gi and hardnesses Hi of rubber layers disposed on outer sides of the carcass in the tire width direction on a line drawn in the tire width direction from a center position of the power receiving coil in the tire radial direction satisfy the following relationship: 80≦(DH / WH)×[ΣGiHi]≦800. [Aspect 18] The tire according to any one of Aspects 15 to 17, wherein the folded end of the carcass is located on the tire radially outer side or the tire radially inner side of a tire radial direction region CW in which the power receiving coil is provided.Aspect 19: The tire according to any one of Aspects 1 to 18, wherein a ratio Rc(CHD / CHI) of a tire radial direction dimension CHD (mm) from a tire radially innermost position in a region immediately above the contact of the tire when in contact with the tire to a tire radially outermost position of the power receiving coil to a tire radially outermost position of the power receiving coil when not in contact with the tire, and a ratio Rs(SHD / SHI) of a tire radial direction length SHD (mm) of the region immediately above the contact of the tire when in contact with the tire to a tire radial direction length SHI (mm) when not in contact with the tire, satisfies 1.05<Rc / Rs<1.35. [Aspect 20] A tire comprising a tread portion having a tread surface, a pair of bead portions, a pair of sidewall portions provided between the tread portion and the bead portions, a reinforcing layer having steel cords, and a power receiving coil that receives power supplied by an AC magnetic field from outside the tire, wherein the reinforcing layer has an area ratio of a portion excluding the steel cords to an area of ​​the reinforcing layer in a front view of 0.1 or more and 0.7 or less. [Aspect 21] The tire according to Aspect 20, wherein the reinforcing layer is a belt provided in the tread portion, and the belt has an area ratio of a portion excluding the steel cords to an area of ​​the belt in a front view of 0.1 or more and 0.5 or less. [Aspect 22] The tire according to Aspect 20, wherein the reinforcing layer is provided in a region in the tire radial direction from an end of the belt in the tire width direction to an outermost position of a bead core in the tire radial direction, and the area ratio of a portion excluding the steel cords to an area of ​​the reinforcing layer in a front view of 0.3 or more and 0.7 or less. [Aspect 23] The tire according to any one of Aspects 20 to 22, wherein the interval between adjacent steel cords included in the reinforcing layer is 0.4 mm or more and 2.4 mm or less. [Aspect 24] The tire according to any one of Aspects 20 to 23, wherein the cross-sectional circumference perpendicular to the longitudinal direction of the steel cord is 1.5 mm or more and 7.0 mm or less. [Aspect 25] The tire according to any one of Aspects 20 to 24, wherein the steel cord is made of 1 to 6 filaments. [Aspect 26] The tire according to any one of Aspects 20 to 25, wherein the winding width of the power receiving coil is larger than the interval between adjacent steel cords included in the reinforcing layer.[Aspect 27] The tire of any one of Aspects 20 to 26, wherein a distance WD (m) between the reinforcing layer and the power receiving coil and a frequency f (kHz) of the supplied magnetic field satisfy the following formula (1): 4≦f×WD≦60 (1) [Aspect 28] The tire of any one of Aspects 20 to 27, wherein the distance WD (m) between the reinforcing layer and the power receiving coil is 2.0 to 25 times the spacing between adjacent steel cords included in the reinforcing layer. [Aspect 29] The tire of any one of Aspects 20 to 28, wherein the reinforcing layer has a plurality of main portions, each of which has a spacing W1 between adjacent steel cords, and a void portion disposed between the plurality of main portions, the spacing W2 between adjacent main portions in the void portion being 1.5 to 3.5 times the spacing W1. [Aspect 30] The tire according to any one of Aspects 20 to 29, wherein the reinforcing layer is a belt provided in the tread portion, and the power receiving coil is provided on the tire inner surface radially inward of the belt, and the power receiving coil is a loop coil centered on the tire rotation axis. [Aspect 31] The tire according to any one of Aspects 20 to 30, wherein the reinforcing layer is provided in a region in the tire radial direction from an end of the belt in the tire width direction to an outermost position in the tire radial direction of a bead core, and wherein, when viewed in a meridian cross section of the tire in an unloaded state, SH is the tire radial direction length from a bead toe to the tread surface, the power receiving coil is provided on the tire inner surface in a region within 50% of the tire radial direction length SH, and the power receiving coil is a loop coil centered on the tire rotation axis. [Aspect 32] The tire according to any one of Aspects 20 to 31, in a state where the tire is mounted on a regular rim.

[0011] The tire and wireless power transfer system according to the first aspect of the present invention can suppress a decrease in power transfer efficiency even on wet road surfaces. In the tire according to the second aspect of the present invention, improvements are made to the fixing method of the power receiving coil at the installation location, assuming that the power receiving coil is installed outside the rim. As a result, the tire according to the present invention can improve power transfer efficiency. According to the third aspect of the present invention, the magnetic field reaching the power receiving coil from the power transmitting coil is less likely to be obstructed, suppressing a decrease in power transfer efficiency.

[0012] FIG. 1 is a meridian cross-section of the tire on the ground contact surface side according to the first embodiment. FIG. 2 is a plan view showing an example of a tread surface of the tire according to the first embodiment. FIG. 3 is a meridian cross-section of a tire according to a modified example of the first embodiment. FIG. 4 is a diagram showing a tire (a portion on one side in the tire width direction with respect to the tire equatorial plane in a tire meridian cross-section of the tire on the non-ground contact surface side) on which a power transmitting coil and a power receiving coil are provided for the wireless power transfer system according to the first embodiment. FIG. 5 is a diagram showing that the power receiving coil is located within the power transfer region of the power transmitting coil for the wireless power transfer system according to the first embodiment. FIGS. 1A and 1B show examples in which the power transfer direction is the tire width direction, and FIGS. 1C and 1D show examples in which the power transfer direction is inclined with respect to the tire width direction. FIG. 6 is a diagram showing the installation position of the power transmitting coil for the wireless power transfer system according to the first embodiment. FIG. 7 is a partial meridian cross-section showing the installation positions of the power transmitting coil and the power receiving coil for the wireless power transfer system according to the first embodiment. 8 shows an arrangement of power receiving coils (an arrangement in which the power receiving coils are not continuous in the tire circumferential direction, unlike the case of FIG. 1 ), with (A) to (F) showing examples of power receiving coils 40 each consisting of two, three, four, five, six, and eight sets of power receiving coil elements 40 a, respectively, (G) showing an example in which multiple power receiving coil elements 40 a are stacked in the tire radial direction, and (H) showing an example in which some of the multiple power receiving coil elements extend at an angle with respect to the tire radial direction. FIG. 9 is a meridian cross section (half in the tire width direction) of the tire shown in FIG. 1 showing a power supply arrangement in which power is supplied from the power receiving coil to an electronic device attached to the tire cavity surface via a power line. FIG. 10 is a meridian cross section of a tire according to a second embodiment, showing one side in the tire width direction, based on the tire equatorial plane CP. Fig. 11 is a side view of the tire shown in Fig. 10 mounted on a rim and pressurized to a normal internal pressure, (A) showing the tire not in contact with the ground (i.e., under no load) and (B) showing the tire in contact with the ground (when a load of 80% of the normal load is applied). Fig. 12 is a meridian cross-sectional view of a tire according to a third embodiment. Fig. 13 is a front view showing a steel cord of a reinforcing layer according to the third embodiment. Fig. 14 is a meridian cross-sectional view showing an example of the position of a power receiving coil provided in a tire according to the third embodiment. Fig. 15 is a cross-sectional view of a strand of a steel cord.FIG. 16 is a front view schematically showing the size relationship between the steel cord of the reinforcing layer and the power receiving coil according to the third embodiment. FIG. 17 is a meridian cross-sectional view showing the positional relationship between the reinforcing layer and the power receiving coil of the tire according to the third embodiment. FIG. 18 is a schematic diagram (1) showing the relationship between the reinforcing layer, the power receiving coil, and the magnetic field of the tire according to the third embodiment. FIG. 19 is a schematic diagram (2) showing the relationship between the reinforcing layer, the power receiving coil, and the magnetic field of the tire according to the third embodiment. FIG. 20 is a front view schematically showing an example of a steel cord according to the third embodiment, where (A) is a view of one reinforcing layer and (B) is a view of two reinforcing layers stacked in the thickness direction. FIG. 21 is a meridian cross-sectional view used to explain the installation position of the power receiving coil according to the third embodiment. FIG. 22 is a perspective view showing the position of the power receiving coil relative to the tire according to the third embodiment. FIG. 23 is a meridian cross-sectional view used to explain another installation position of the power receiving coil relative to the tire according to the third embodiment. FIG. 24 is a perspective view showing another position of the power receiving coil relative to the tire according to the third embodiment. Fig. 25 is a meridional cross-sectional view illustrating yet another installation position of the power receiving coil according to the third embodiment. Fig. 26 is a perspective view showing yet another position of the power receiving coil with respect to the tire according to the third embodiment.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the tire radial direction refers to the direction perpendicular to the tire rotation axis, the tire radially inner side refers to the side toward the tire rotation axis in the tire radial direction, and the tire radially outer side refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotation axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the tire rotation axis, the tire widthwise inner side refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and the tire widthwise outer side refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane refers to a plane that is perpendicular to the tire rotation axis and passes through the center of the tire width.

[0014] Similarly, in the following description, a regular rim refers to an "application rim" defined by JATMA, a "design rim" defined by TRA, or a "measuring rim" defined by ETRTO.

[0015] Similarly, in the following description, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Inflation Pressures" specified by ETRTO. Also, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Load Capacity" specified by ETRTO.

[0016] <Tire> 1. First Embodiment A tire according to a first aspect of the present invention (Basic Mode 1 and Additional Modes 2 to 8 shown below) and a first embodiment of a wireless power supply system according to the present invention (Basic Mode 9 and Additional Modes 10 to 14 shown below) will be described in detail below with reference to the drawings. Note that these embodiments do not limit the present invention. Furthermore, the components of each embodiment include those that are easily replaceable by a person skilled in the art, or those that are substantially identical. Furthermore, each embodiment can be arbitrarily combined within the scope that is obvious to a person skilled in the art. [Basic Mode 1] A basic mode of a tire according to a first embodiment of the present invention will be described below. FIG. 1 is a meridian cross section of a tire according to this embodiment. Note that this figure shows the tire portion on the contact surface side when mounted on a rim, with the normal internal pressure applied, and under no load.

[0017] 1 , a tire 10 according to this embodiment has, from the inner side to the outer side in the tire radial direction, a bead portion A, a sidewall portion B, a shoulder portion C, and a tread portion D. An inner liner 12 exposed to the tire cavity surface is provided in the region from the bead portion A to the tread portion D, and a carcass 18 including a main portion 18a extending along the inner liner 12 and a folded portion 18b folded around a bead core 14 and a bead filler 16 is provided on the opposite side of the inner liner 12 from the tire cavity surface, and a belt 20 (belt layers 20a, 20b) is provided on the outer side in the tire radial direction of the carcass 18 in the tread portion D.

[0018] In the tire 10 configured as described above, the inner liner 12 is a layer for blocking gas that comes into contact with the tire cavity surface. The inner liner 12 can be configured with a single inner liner layer, or can be configured with multiple inner liner layers stacked in the tire radial direction at the tire equatorial plane CP. The inner liner 12 includes at least one layer made of rubber or resin with low air permeability, and can include an adhesive layer at least in the portion that contacts the carcass 18 as other layers.

[0019] The bead core 14 is, for example, a ring-shaped reinforcing material made of bundled cords, and may have a structure in which a plurality of bead wires made of steel cords or organic fiber cords are covered with rubber. The bead filler 16 is a member for increasing the rigidity of the bead portion A, and may have a substantially inverted triangular shape as shown in Fig. 1, in which the tire width direction dimension at the tire radially inner end is substantially equal to the tire width direction dimension of the bead core 14 at the tire radially outer end, and the tire width direction dimension gradually decreases toward the tire radially outer side.

[0020] The carcass 18 is a component that forms the framework of the tire 10 and is composed of at least one carcass layer (carcass ply), with each carcass layer having a configuration in which a plurality of carcass cords are coated with rubber. Generally, steel cords or organic fiber cords are used as the carcass cords. However, in the tire 10 according to this embodiment, as described below, it is preferable to use a non-magnetic material for the carcass cords in order to prevent a magnetic field that is generated in the sidewall portion B so as to penetrate the tire cavity surface of the inner liner 12 substantially perpendicularly from being obstructed by a metal member. For example, organic fibers such as rayon, polyester, polyamide, and aramid can be used as the non-magnetic material.

[0021] The belt 20 is a reinforcing layer provided on the radially outer side of the carcass 18, and tightens the carcass 18 to increase the rigidity of the tread portion, improving steering stability, and reducing strain deformation and rolling resistance. The belt 20 can be composed of multiple belt layers (two belt layers 20a, 20b in the example shown in FIG. 1) laminated in the radial direction of the tire in the tread portion D. Each of the belt layers 20a, 20b has a configuration in which multiple belt cords are coated with rubber. Generally, steel cords or organic fiber cords are used as the belt cords. As the belt cords, magnetic materials such as steel cords can of course be used, but non-magnetic materials (including paramagnetic materials and diamagnetic materials) can also be used.

[0022] The side tread 26 is disposed so as to connect the bead portion A and the tread portion D. The cap tread 30 is formed on a tread surface 34, which is the surface of the tread portion D, over the entire tire contact area. Note that both the side tread 26 and the cap tread 30 can use conventional rubber members according to the required characteristics of each.

[0023] Assuming the presence of the components 12 to 30 of the tire 10 described above, the tire 10 according to this embodiment includes a power receiving coil 40 ( FIG. 1 ) on the inner side of the tire cavity surface in the tire width direction, which receives AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10. The power receiving coil 40 may be provided in contact with the inner liner 12, or may be embedded in the inner liner 12. The power receiving coil 40 may also be provided so as to be fixed to the inner liner 12 via a fixing member other than rubber (for example, made of a non-magnetic material, but the fixing portion may be made of a rubber with a relatively high thermal conductivity, such as silicone rubber) ( FIG. 1 ).

[0024] In power supply using the tire 10 according to this embodiment, DC current obtained from an on-board battery (not shown) is first converted into AC current by an AC power supply device, and this AC current is then applied to a power transmission coil (attached, for example, to the tire-side surface of a knuckle, which is a part of the steering axle of the vehicle), generating an AC magnetic field around the power transmission coil. This AC magnetic field interlinks with the power receiving coil 40, generating an induced electromotive force in the power receiving coil 40, thereby supplying power.

[0025] In the tire 10 according to this embodiment, when viewed in a tire meridian section on the contact patch side, the power receiving coil 40 is provided radially inward of the outermost position OP where the first imaginary line L1, which forms an angle α of 15° with the tire equatorial plane CP, meets the tire side surface.

[0026] The first imaginary line L1 is inclined at a predetermined angle α toward the tire side surface of interest with respect to the tire equatorial plane CP. When focusing on the tire side surface on the right side of the paper in FIG. 1 , the first imaginary line L1 is inclined to the right with respect to the tire equatorial plane. Similarly, when focusing on the tire side surface on the left side of the paper in FIG. 1 , the first imaginary line L1 is inclined to the left with respect to the tire equatorial plane. The angle α between the tire equatorial plane CP and the first imaginary line L1 may be 10° or 5°.

[0027] The tire sidewall is the surface of the tire 10 that is opposite the tire cavity surface and visible from the outside in the tire width direction. The outermost position OP is a position defined on the tire sidewall when the tire is mounted on a rim, normal internal pressure is applied, and no load is applied. The outermost position OP is the position on the tire sidewall that the first imaginary line L1 first contacts when the first imaginary line L1 is translated from the outside of the tire 10 in the tire width direction to the inside in the tire width direction. In the case of a tire whose tire sidewall has a shape that bulges outward in the tire width direction in the tire meridian cross section, the outermost position OP may be a position radially outward of the position at which the tire width direction length is at its maximum. The power receiving coil 40 is located radially inward of the outermost position OP. It is preferable that at least some of the conductors included in the power receiving coil 40 are located radially inward of the outermost position OP, and it is more preferable that the entire power receiving coil 40 be located radially inward of the outermost position OP.

[0028] (Function, etc.) When the tire 10 comes into contact with a wet road surface, water adheres to the tire sidewall in the range from the contact patch to the tire sidewall. However, water is less likely to adhere to the tire sidewall radially inward of the outermost position OP because it is relatively far from the wet road surface. When the tire 10 rolls, water adhering to the tire sidewall radially inward of the outermost position OP moves radially outward from the tire sidewall due to centrifugal force accompanying the rotation of the tire 10, and may move at least radially outward from the outermost position OP. Therefore, water is less likely to adhere to the tire radially inward from the outermost position OP of the tire 10, and adhering water moves radially outward from the tire sidewall during a circumferential rotation of the tire, for example, 120°, after coming into contact with the wet road surface. Therefore, water is less likely to remain on the tire sidewall radially inward from the outermost position OP when receiving power. Because the power receiving coil 40 is located radially inward from the outermost position OP, it is less susceptible to water when receiving power. Therefore, the tire 10 can suppress a decrease in power supply efficiency even in rainy weather, etc.

[0029] Snow-melting agents, especially those used in cold regions, are generally compounds such as sodium chloride or calcium chloride, which dissolve in water to form an electrolyte. Because the electrolyte can be considered a type of dielectric, it can affect the magnetic field and further reduce power supply efficiency.

[0030] In contrast, even when tire 10 is driven on a wet surface containing snow-melting agent, the decrease in power supply efficiency can be suppressed by providing power receiving coil 40 in a portion where water is less likely to adhere, i.e., radially inward from outermost position OP.

[0031] [Additional Form 2] In Basic Form 1, when the tire radial length from the bead toe 32 to the tread surface 34 is SH in a meridian cross section of the tire in an unloaded state, it is preferable that the power receiving coil 40 be provided radially outward from a position 15% of the tire radial length SH from the bead toe 32 (Additional Form 2), and it is more preferable that the power receiving coil 40 be provided radially outward from a position 20% of the length SH.

[0032] The power receiving coil 40 is preferably provided radially outward of the innermost position MP. The innermost position MP is a position 15% of the tire radial length SH from the bead toe 32. The length SH is the tire radial length from the bead toe 32 to the tread surface 34 when the tire is mounted on a rim, normal internal pressure is applied, and no load is applied. The innermost position MP is more preferably a position 20% of the tire radial length SH from the bead toe 32.

[0033] By locating the power receiving coil 40 radially outward of the innermost position MP, a sufficient gap is provided between the power receiving coil 40 and the rim 6 when the tire 10 is mounted on the rim 6. The rim 6 is made of metal, and therefore blocks the magnetic field generated by the current flowing through the power transmitting coil. A rim 6 with water on it can have a greater effect on the magnetic field, further reducing the power supply efficiency.

[0034] When the tire 10 is mounted on the rim 6, the power receiving coil 40 is provided at a position sufficiently distant from the rim 6, so that the magnetic field is less likely to be affected by the rim 6, thereby suppressing a decrease in power supply efficiency. It is preferable that at least some of the conductors included in the power receiving coil 40 are provided radially outward from the innermost position MP, and it is more preferable that the entire power receiving coil 40 is provided radially outward from the innermost position MP.

[0035] [Additional Configuration 3] In Basic Configuration 1 or a configuration in which Basic Configuration 1 and Additional Configuration 2 are added, it is preferable that the power receiving coil 40 be provided on the tire inner surface opposite the tire outer surface having the tread surface 34 (Additional Configuration 3).

[0036] The tire outer surface has a tread surface 34 and is the surface of the tire 10 that is visible from the outside when the tire 10 is mounted on a rim. The tire inner surface (also referred to as the "tire cavity surface") is the surface opposite the tire outer surface and is the surface of the tire 10 that is not visible from the outside when the tire 10 is mounted on a rim. The power receiving coil 40 is provided on the tire inner surface. By providing the power receiving coil 40 on the tire inner surface, it is possible to prevent the power receiving coil 40 from coming into contact with rainwater.

[0037] Furthermore, when the power receiving coil 40 is attached to the rim, it is necessary to assemble the rim to the tire without damaging the power receiving coil, which may result in poor workability when assembling the rim.

[0038] By providing the power receiving coil 40 on the inner surface of the tire 10 , the power receiving coil 40 can be prevented from being damaged when the tire 10 is mounted to the rim 6 .

[0039] [Additional Form 4] In a form obtained by adding Additional Form 2 or 3 to Basic Form 1 or Basic Form 1, in a power receiving vicinity area AR between an intersection P1 between a second imaginary line L2 inclined 30° radially inward in the tire direction from an inner end of the power receiving coil 40 toward the outer side in the tire width direction and the tire outer surface, and an intersection P2 between a third imaginary line L3 inclined 30° radially outward in the tire direction from an outer end of the power receiving coil 40 in the tire radial direction and the tire outer surface, it is preferable that the height of the unevenness of the tire outer surface is 1 mm or less over 50% or more of the area of ​​the power receiving vicinity area AR (Additional Form 4).

[0040] The vicinity of the power receiving coil 40 provided on the tire 10 is referred to as the power receiving vicinity area AR ( FIG. 1 ). The power receiving vicinity area AR is an area defined by a second imaginary line L2 and a third imaginary line L3 in the tire meridian section on the contact patch side. The second imaginary line L2 is a line inclined 30° radially inward from the upper end of the power receiving coil 40 provided on the tire 10 in the tire radial direction toward the outer side in the tire width direction in the tire meridian section on the contact patch side. The third imaginary line L3 is a line inclined 30° radially outward from the lower end of the power receiving coil 40 provided on the tire 10 in the tire radial direction toward the outer side in the tire width direction in the tire meridian section on the contact patch side. The power receiving vicinity area AR is an area of ​​the tire outer surface sandwiched between an intersection P1 between the second imaginary line L2 and the tire outer surface and an intersection P2 between the third imaginary line L3 and the tire outer surface. The power receiving vicinity area AR is an annular area centered on the tire rotation axis.

[0041] The tire 10 may have unevenness on its sidewall, such as stampings, markings, serrations, and decorative patterns. The tire 10 has an unevenness height of 1 mm or less formed on its surface (tire sidewall) in the power-receiving vicinity area AR. The unevenness is a surface shape having peaks and valleys. The height of the unevenness refers to the length in the rubber thickness direction between the position where the peak height is greatest and the position where the valley depth is greatest. The tire 10 may have unevenness, i.e., stampings, markings, serrations, and decorative patterns, in an area in the power-receiving vicinity area AR that accounts for 50% or more of the area of ​​the power-receiving vicinity area AR, and the height of the unevenness in the area having the unevenness is 1 mm or less. By having an unevenness height of 1 mm or less, the tire 10 is less likely to accumulate water in the uneven portions. Therefore, the tire 10 is prevented from accumulating water in the uneven portions of the tire sidewall.

[0042] It is preferable that unevenness be 1 mm or less over 70% or more of the area of ​​the power-receiving vicinity region AR of the tire 10. It is also preferable that unevenness be 1 mm or less on the tire sidewall other than the power-receiving vicinity region AR of the tire 10.

[0043] [Additional Configuration 5] In Basic Configuration 1 or a configuration in which Basic Configuration 1 and Additional Configuration 4 are added, it is preferable that a coating layer made of a component other than rubber be provided on the tire outer surface in the power-receiving vicinity area AR (Additional Configuration 5).

[0044] Because the rubber component that makes up the tire 10 is highly water-repellent, water adheres to the tire's outer surface as droplets and tends to remain on the tire's outer surface. By providing a coating layer on the tire's outer surface in the power-receiving vicinity area AR, the contact angle of the tire's outer surface is reduced. From the viewpoint of achieving both conformability to tire deformation and water repellency, the coating layer can be made of, for example, a urethane resin or a silicone resin. This causes water droplets that come into contact with the tire's outer surface to spread and flow away in a film-like manner, making it difficult for water droplets to remain on the tire's outer surface. Therefore, the tire 10 can further reduce the impact that water adhering to the tire's outer surface has on the magnetic field.

[0045] [Additional Form 6] In Basic Form 1 or a form in which any one of Additional Forms 2 to 5 is added to Basic Form 1, it is preferable that the groove area ratio DR in the tread portion D is 12% or more and 38% or less, and that the groove area ratio MR in a region M on the inner side of the tire equatorial plane CP when mounted on the vehicle is greater than the groove area ratio ER in a region E on the outer side of the tire equatorial plane CP when mounted on the vehicle, with the difference being 3.5 percentage points or more (Additional Form 6).

[0046] The tire 10 has a pattern made up of a plurality of grooves formed in a tread portion D. For example, as shown in Fig. 2 , the tire 10 includes three circumferential main grooves 36, one circumferential narrow groove 37, and a plurality of lug grooves 31. The tread portion D shown in Fig. 2 is merely an example of the tire 10, and the tire 10 of this embodiment is not limited to the tread pattern shown in Fig. 2 .

[0047] The groove area ratio is the ratio between the sum of the areas of grooves arranged in a predetermined region of the tread portion D and the sum of the groove area and land area within that region (=contact area). The groove area ratio is defined as groove area / contact area. The groove area refers to the opening area of ​​the groove in the contact patch. The grooves refer to the circumferential main grooves 36, circumferential narrow grooves 37, and lug grooves 31 of the tread portion D, and do not include sipes. The land area refers to the contact area between the tire 10 and the contact patch. The groove area and contact area are measured at the contact surface between the tire and a flat plate when the tire 10 is mounted on a specified rim, pressurized to a specified internal pressure, placed perpendicular to a flat plate in a stationary state, and subjected to a load corresponding to a specified load (80% of the maximum load capacity).

[0048] The tire 10 has a groove area ratio DR within the contact patch of 12% or more and 38% or less, and the groove area ratio MR in a region M from the tire equatorial plane CP to the inner side where the tire is mounted on the vehicle is greater than the groove area ratio ER in a region E from the tire equatorial plane CP to the outer side where the tire is mounted on the vehicle, with the difference (MR - ER (% points)) being 3.5 percentage points or more. Region M is the region from the tire equatorial plane CP to the contact edge on the inner side where the tire is mounted on the vehicle. Region E is the region from the tire equatorial plane CP to the contact edge on the outer side where the tire is mounted on the vehicle. The contact edge is the outer edge in the tire width direction in the contact patch when the tire is mounted on a rim, normal internal pressure is applied, and a load of 80% of the normal load is applied. A larger groove area ratio can suppress water splashing during driving. By keeping the groove area ratio DR throughout the entire tread portion D within the above range, the wear performance and wet performance of the vehicle can be maintained. Furthermore, the tire 10 has a larger groove area ratio MR in the region M from the tire equatorial plane CP on the vehicle mounting inner side, which can suppress water splashing onto the vehicle mounting inner side. Therefore, when the power receiving coil 40 is installed on the vehicle mounting inner side of the tire 10, water can be prevented from adhering to the tire side surface on the vehicle mounting inner side, thereby suppressing a decrease in power supply efficiency. It is more preferable that the groove area ratio DR is 15% or more and 35% or less, and the difference between the groove area ratio MR and the groove area ratio ER is 4 percentage points or more, and even more preferable that the groove area ratio DR is 17% or more and 33% or less, and the difference between the groove area ratio MR and the groove area ratio ER is 4.5 percentage points or more.

[0049] [Additional Form 7] In the basic form 1 or the form in which the basic form 1 and the additional form 6 are added, it is preferable that the length Aw between a pair of outermost positions OP and the contact width Tw under a load of 80% of the normal load satisfy the following formula (1) (additional form 7).

[0050] Tw≦0.88×Aw (1)

[0051] As described above, the outermost position OP is a position defined on the tire sidewall. The outermost position OP is the position on the tire sidewall that the first imaginary line L1 first comes into contact with when the first imaginary line L1 is translated from the outer side of the tire 10 in the tire width direction to the inner side in the tire width direction. The length Aw is the distance in the tire width direction between the outermost positions OP defined on the tire sidewalls on both sides of the tire 10. The contact width Tw refers to the maximum dimension in the tire width direction of the area that comes into contact with the road surface when the tire is mounted on a standard rim, standard internal pressure is applied, and a load of 80% of the standard load is applied. The outermost position OP is a position defined on the tire sidewall when the tire is mounted on a rim, standard internal pressure is applied, and no load is applied.

[0052] When the length Aw between the outermost positions OP and the contact width Tw satisfy the above formula (1), spray of water generated between the wet road surface and the contact patch of the tire 10 is less likely to adhere to the tire sidewall radially inward of the outermost positions OP. In other words, the smaller the contact width Tw is compared to the length Aw between the outermost positions OP in the above formula (1), the more the outermost positions OP of the tire 10 bulge outward in the tire width direction. Therefore, spray of water generated between the wet road surface and the contact patch of the tire 10 is less likely to extend beyond the outermost positions OP and adhere to the tire sidewall radially inward of the tire.

[0053] [Additional Configuration 8] In the basic configuration 1 or the configuration in which any one of additional configurations 2 to 7 is added to the basic configuration 1, it is preferable that the tire is in a state of being assembled to a regular rim (additional configuration 8).

[0054] The tire 10 is mounted on a rim 6 for use. In this case, the power receiving coil 40 may be provided on the rim 6, as shown in FIG. 3 . For example, as shown in FIG. 3 , the power receiving coil 40 may be provided at position 40A on the rim inner surface facing the tire cavity surface. The power receiving coil 40 provided at position 40A has a conductor wound in a cylindrical shape around the tire rotation axis so that the conductor is aligned in the tire width direction. In another example, the power receiving coil 40 may be provided at position 40B on the rim inner surface so that the conductor is aligned in the tire radial direction. In this case, the power receiving coil 40 has a conductor wound in a spiral shape around the tire rotation axis. In yet another example, the power receiving coil 40 may be provided at position 40C on the rim outer surface opposite the rim inner surface facing the tire cavity surface. The power receiving coil 40 provided at position 40C has a conductor wound in a cylindrical shape around the tire rotation axis so that the conductor is aligned in the tire width direction.

[0055] <Wireless Power Supply System> [Basic Form 9] Fig. 4 is a diagram showing a tire 10 (a portion on one side in the tire width direction with respect to the tire equatorial plane CP in a tire meridian cross section of the tire on the non-ground-contact side) provided with a power transmitting coil 52 and a power receiving coil 40 in a wireless power supply system 50 according to this embodiment. Note that Fig. 4 shows the tire portion on the side opposite the ground contact surface when the tire is mounted on a rim, pressurized to a normal internal pressure, and subjected to a load of 80% of the normal load (the same applies hereinafter to the wireless power supply system invention). The power transmitting coil 52 shown in Fig. 4 is a coil whose winding axis is in the tire width direction. However, the portion of the power transmitting coil 52 extending in the tire radial direction may extend only in the tire radial direction, or may extend in at least one of the tire circumferential direction and the tire width direction in addition to the tire radial direction.

[0056] The power transmission coil 52 shown in the figure forms a resonant circuit using a capacitor and a coil, and is attached, for example, to the tire-side surface of a knuckle or hub carrier, which are parts of a steering axle of a vehicle (not shown), or to any part that makes up a strut structure.

[0057] The power transmitting coil 52 is preferably installed in an unsprung part of the vehicle. The unsprung part includes, for example, a knuckle, a brake caliper, and a damper case of a strut suspension. By installing the power transmitting coil 52 in the unsprung part, the distance between the power transmitting coil 52 and the power receiving coil 40 installed in the tire 10 can be maintained constant even when the vehicle moves up and down due to unevenness in the road surface.

[0058] In the wireless power transfer system 50 shown in FIG. 4 , the power transmitting coil 52 can be provided in a damper case (not shown) of a strut suspension. For example, the power transmitting coil 52 may be provided in a damper case for a front wheel or a damper case for a rear wheel. This allows the power transmitting coil 52 to face the power receiving coil 40 in the tire width direction, even when the tire 10 moves up and down due to unevenness in the road surface, and to transmit power in the tire width direction while avoiding the belt and bead cores. Therefore, the wireless power transfer system 50 can improve power transfer efficiency.

[0059] The power transmitting coil 52 may also be provided on a member that moves together with the tire 10 in response to steering, such as a knuckle (not shown) of a multi-link suspension. This allows the distance between the power transmitting coil 52 and the power receiving coil 40 provided on the tire 10 to be kept constant even during steering. This allows the tire 10 to receive a stable power supply while traveling.

[0060] Next, the power receiving coil 40 shown in Fig. 4 has the same configuration as the power receiving coil shown in Fig. 1, and a resonant circuit is formed by a capacitor and a coil. Note that the tire 10 shown in Fig. 4 is a tire of the basic configuration 1 related to the tire 10 described above, and a tire that adds at least one of additional configurations 2 to 8 to the basic configuration 1, and its actions, functions, etc. are as described above.

[0061] Under these assumptions, the wireless power feed system 50 according to this embodiment is a magnetic field resonance type wireless power feed system that uses an AC magnetic field, and as shown in Fig. 4, power is supplied to the power transmitting coil 52, and the power is transmitted to the power receiving coil 40 by the AC magnetic field. With this wireless power feed system 50, as described above, it is possible to improve the power feed efficiency.

[0062] Here, in order to drive the sensors and associated electric circuits installed inside the tire 10, it is preferable to transmit power of 0.1 to 15 W at a frequency of 1 to 20 MHz. More preferably, AC power with a frequency of 6.78 to 13.56 MHz is supplied to the power transmitting coil 52.

[0063] Furthermore, the shortest distance between the power transmitting coil 52 and the power receiving coil 40 (hereinafter sometimes referred to as the "transmission gap G") is preferably 10 mm or more and 80 mm or less. Here, the transmission gap G is a value measured when the tire 10 is mounted on a rim, pressurized to the normal internal pressure, attached to a vehicle, and stopped on flat ground. The transmission gap G is the shortest distance between the power transmitting coil 52 and the power receiving coil 40, that is, in FIG. 4 , the distance between the innermost position of the power transmitting coil 52 in the tire width direction and the outermost position of the power receiving coil 40 in the tire width direction.

[0064] Setting the transmission gap G to 10 mm or more can prevent excessive fluctuations in received power caused by fluctuations in the relative positions of the power transmitting coil 52 and the power receiving coil 40 (shown in FIG. 4 ) in the direction of power transmission. This simplifies the circuit configuration connected to the power receiving coil 40, making it possible to easily supply stable power to an electronic device. The fluctuations in received power depend on fluctuations in the relative positions between the two coils 52, 40 caused by slight expansion of the tire 10 due to centrifugal force while the tire 10 is rotating. Specifically, as the tire rotation speed increases, the tire 10 expands in the tire radial direction, causing the power receiving coil 40 to move radially outward (upper side in FIG. 4 ), while the position of the power transmitting coil 52 remains unchanged, resulting in a change in the relative positions between the two coils 52, 40.

[0065] In contrast, by setting the transmission gap G to 80 mm or less, the strength of the magnetic field generated between the two coils 52, 40 does not become excessively small, and power can be efficiently supplied by an AC magnetic field.

[0066] The transmission gap G is more preferably 12 mm or more and 75 mm or less, and most preferably 15 mm or more and 70 mm or less.

[0067] By adopting the above-described range of the transmission gap G, power range, and frequency band, not only can the temperature rise of the power receiving coil 40 be suppressed, but also an increase in the number of coil turns (and thus an increase in coil weight) is unnecessary, so that the rolling resistance of the tire is not increased, power can be fed efficiently, and excellent power feeding efficiency can be achieved. Furthermore, in particular, according to the above-described range of the transmission gap G, excellent power feeding efficiency can be obtained when power is transmitted using the tire structure in magnetic field resonance type wireless power feeding in the above frequency band.

[0068] 4, the power transmitting coil 52 is disposed so as to extend in the tire radial direction, but this embodiment is not limited to such an arrangement. That is, as long as the transmission gap G described above is within a predetermined range, the extension direction of the power transmitting coil 52 may be inclined with respect to the tire radial direction.

[0069] [Additional Embodiment 10] In the basic embodiment 9, it is preferable that the power receiving coil 40 is disposed on the inner side of the vehicle mounting portion (additional embodiment 10).

[0070] The inner side of the tire 10 mounted on the vehicle faces the wheelhouse when the tire 10 is mounted on the vehicle. By locating the power receiving coil 40 on the inner side, it is less susceptible to water. That is, the inner side of the tire 10 is less likely to come into contact with rain or water splashed by oncoming vehicles during rainy weather. Furthermore, when the tire 10 is mounted in a specified orientation on the vehicle, the tire outer surface, which is more visible to the public, is often provided with irregularities, such as stampings, commendations, serrations, and decorative patterns. Such irregularities tend to trap water that adheres to the tire, and therefore have a significant impact on the power receiving coil 40. Therefore, the tire outer surface on the inner side of the tire 10 is less likely to come into contact with water and have fewer irregularities than the tire outer surface on the outer side of the tire. This reduces the likelihood of water accumulating. Furthermore, locating the power receiving coil 40 on the inner side of the tire allows for greater flexibility in the positioning of the power transmitting coil 52. For these reasons, it is preferable that the power receiving coil 40 be disposed on the inside of the vehicle. When the power receiving coil 40 is disposed on the inside of the vehicle, the transmission gap G can be easily set within the above range by installing the power transmitting coil 52 inside the wheelhouse.

[0071] 5A and 5B are diagrams showing a wireless power supply system 50 according to this embodiment in which the power receiving coil 40 is located within a power supply region of the power transmitting coil 52, with (A) and (B) showing an example in which the power supply direction is the tire width direction, and (C) and (D) showing an example in which the power supply direction is a direction obliquely downward with respect to the tire width direction. Note that in Fig. 5, (A) and (C) are examples in which the power supply region of the power transmitting coil 52 includes an inner portion of the power receiving coil 40 in the tire radial direction, and (B) and (D) are examples in which the power supply region of the power transmitting coil 52 includes an outer portion of the power receiving coil 40 in the tire radial direction.

[0072] In a configuration in which Additional Configuration 10 is added to Basic Configuration 9, as shown in FIGS. 5(A) to 5(D), it is preferable that at least a portion of the power receiving coil 40 is located within a power supply region that extends in the winding axis direction of the power transmitting coil 52 across both longitudinal end portions of the power transmitting coil 52 in a tire meridian cross section (Additional Configuration 11).

[0073] Here, the positional relationship between the power receiving coil 40 and the power transmitting coil 52 is measured with the tire 10 mounted on a rim, pressurized to the normal internal pressure, attached to a vehicle, and stopped on flat ground. More preferably, the power transmitting coil 52 is arranged so that the power transmitting coil radial area defined by the length between both ends of the tire in the radial direction overlaps at least a portion of the power receiving coil radial area defined by the length between both ends of the tire in the radial direction. Such an arrangement can achieve higher power supply efficiency.

[0074] 5A and 5B is disposed on the outer side in the tire width direction, at a position corresponding to a partial region in the tire circumferential direction. The power receiving coil 40 provided on the tire cavity surface extends around the entire tire circumferential direction. At least a portion of the power receiving coil 40 is provided in a region obtained by projecting the power transmitting coil radial region onto the tire cavity surface, i.e., a region between points where imaginary lines extending from the tire radially outer end and the tire radially inner end of the power transmitting coil 52 to the tire cavity surface and parallel to the winding axis of the power transmitting coil 52 intersect with the tire cavity surface. For the power receiving coil 40 provided on the tire cavity surface, a portion of the tire radial direction of the power receiving coil 40 is preferably included in the region obtained by projecting the power transmitting coil radial region, and more preferably the entire tire radial direction of the power receiving coil 40 is included in the region obtained by projecting the power transmitting coil radial region.

[0075] In the wireless power supply system 50 according to this embodiment, the power transmission coil 52 is attached to a knuckle or hub carrier (located on the outer side of the sidewall portion B in the tire width direction), which is a component of the steering axle of the vehicle, or to the tire-side surface of one of the components constituting the strut structure. Therefore, when examining the power supply efficiency taking into account the shape of the tire 10, particularly the sidewall portion B, it is desirable that the direction of the magnetic field lines penetrating the tire at the sidewall portion B, and therefore the power supply direction Dp, be approximately the tire width direction, as shown in Figures 5(A) and 5(B) .

[0076] Based on this knowledge, when the power supply direction Dp is set to be substantially the tire width direction as shown in Figures 5(A) and 5(B), power supply can be performed more efficiently, and ultimately excellent power supply efficiency can be achieved.

[0077] Furthermore, in the examples shown in Figures 5(B) and (C), the constituent surfaces (planes normal to the winding axes of each coil in Figures 5(B) and (C)) of the transmitting coil 52 and the receiving coil 40 are parallel to each other, so power can be supplied more efficiently than in the examples shown in Figures 5(A) and (D), and superior transmission efficiency can be achieved.

[0078] 5A and 5D, the constituent surfaces of the power transmitting coil 52 and the power receiving coil 40 do not need to be parallel to each other. This is because, when the magnetic field generated by the power transmitting coil 52 interlinks with the power receiving coil 40, an electromotive force is generated by the AC magnetic field, and there are no restrictions on the relative orientation of the surfaces.

[0079] [Additional Form 12] In a form in which Additional Form 10 or Additional Form 11 is added to Basic Form 9, it is preferable that the power transmission coil 52 be installed within a range of 60° on both sides of the tire circumferential direction, centered on an imaginary line extending vertically upward from the center of the tire (Additional Form 12).

[0080] Typically, when the tire 10 rolls, the power receiving coil 40 deforms in accordance with the deformation of the tire 10 at the contact portion thereof, whereas the power receiving coil 40 is hardly deformed in the portion of the tire 10 away from the contact portion thereof (the upper portion of the tire 10 in FIG. 6 ). For this reason, by installing the power transmitting coil 52 located on the outside of the tire 10 near the upper portion of the tire away from the contact portion of the tire 10 (in a tire circumferential range R of 60° on both sides of an imaginary line extending vertically upward from the tire center O when viewed in the tire width direction), it is possible to suppress fluctuations in the transmission gap G described above when the tire rolls, thereby enabling more efficient power supply and ultimately achieving even better power supply efficiency. Note that the example shown in FIG. 6 is an example in which the power transmitting coil 52 is attached to a wheel well 54, and the tire circumferential range R described above is applied within the wheel well 54.

[0081] It is more preferable that the power transmission coil 52 be installed in a circumferential range of 55° on either side of an imaginary line extending vertically upward from the tire center O when viewed in the tire width direction, and it is extremely preferable that the power transmission coil 52 be installed in a circumferential range of 50° on either side of the imaginary line.

[0082] Furthermore, the shape of the power transmission coil 52 is not particularly limited, but when the power transmission coil 52 is installed, for example, inside a wheelhouse, it is preferable to use a so-called spiral coil, which allows the overall thickness to be reduced.

[0083] [Additional Form 13] In a form in which any one of Additional Forms 10 to 12 is added to Basic Form 9, it is preferable that the power transmission side surface 60 facing the power receiving coil 40 of the power transmission coil unit 56 including the power transmission coil 52 has a contact angle of 50° or more (Additional Form 13).

[0084] As shown in Fig. 7, the power transmission coil unit 56 has a power transmission coil 52 and a case 58 that houses the power transmission coil 52. The case 58 is made of a non-magnetic material. The case 58 is fixed to a vehicle, for example, a wheel well 54, with the power transmission coil 52 housed therein. The case 58 has a power transmission side surface 60 that faces the power receiving coil 40 provided on the tire 10. The power transmission side surface 60 has a contact angle of 50° or more.

[0085] Because the power transmission coil 52 is fixed to the vehicle, centrifugal force does not act on the power transmission coil 52 as it does on the tire 10. Therefore, the power transmission side surface 60 of the case 58 that houses the power transmission coil 52 is water-repellent, which makes it easy for water to fall off the power transmission side surface 60.

[0086] Although the case where the power transmitting coil unit 56 includes the case 58 has been described, the present invention is not limited to this. The power transmitting coil unit 56 may have a power transmitting coil 52 and a resin film that covers the power transmitting coil 52. In this case, the power transmitting side surface refers to the surface of the resin film that faces the power receiving coil 40. The power transmitting coil unit 56 may also be composed of the power transmitting coil 52. In this case, the power transmitting side surface refers to the surface of the power transmitting coil 52 that faces the power receiving coil 40.

[0087] [Additional Form 14] In a form obtained by adding any one of Additional Forms 10 to 13 to Basic Form 9, it is preferable that the angle β that the power transmission side surface 60 of the power transmission coil unit 56 including the power transmission coil 52 makes with the tire radial direction as viewed from the tire meridian cross section is in the range of 70° toward the tire 10 and 30° away from the tire 10, with the tire radial inner end 57 of the power transmission coil unit 56 as the center (Additional Form 14).

[0088] As described above, the power transmitting coil unit 56 may have the power transmitting coil 52 and a case 58 that houses the power transmitting coil 52. As shown in Fig. 7 , the case 58 has a power transmitting side surface 60, and the angle formed by the power transmitting side surface 60, which is centered on the lower end of the power transmitting coil unit 56 in the tire radial direction, and the tire radial direction is defined as β. The angle β is within a range of 70° toward the tire 10 and 30° away from the tire radial direction.

[0089] The power transmission side surface 60 of the power transmission coil unit 56 facing the power receiving coil 40 has an angle β with the tire circumferential direction as viewed from the tire meridian cross section that is within the above range, making it less likely to get wet with water and making it easy to install the power transmission coil unit 56 at an angle and position that allows power to be efficiently supplied to the power receiving coil 40.

[0090] <Other Aspects of Tire and Wireless Power Supply System> The tire and wireless power supply system according to the present invention have been described above. Other aspects of the tire and wireless power supply system according to the present invention will be listed below.

[0091] The carbon content of the inner liner 12, which is a component of the tire 10, is preferably 45 to 75 parts by mass (parts by mass when the rubber is 100; the same applies below), the carbon content of the side tread is 25 to 65 parts by mass, the carbon content of the bead filler 16 is 40 to 80 parts by mass, and the carbon content of the covering rubber of the carcass 18 is 35 to 70 parts by mass. By adopting these respective content amounts, it is possible to achieve the desired rubber physical properties in each rubber layer. Note that, in addition to a reinforcing effect, carbon compounded in rubber typically has ultraviolet absorbing properties and is effective in suppressing rubber degradation. Therefore, even when the content of antioxidant and wax is reduced, it is possible to maintain the contact angle of the tire surface within a desired range while simultaneously achieving the rubber properties required for the tire 10.

[0092] In the wireless power supply system 50 shown in Fig. 4, the power receiving coil 40 is preferably provided in the tire cavity of the sidewall portion B of the tire 10 with its constituent surface facing in the tire width direction. As described above, when the power supply direction by the power transmitting coil 52 is set to be substantially the tire width direction, as shown in Figs. 5A and 5B, by providing the power receiving coil 40 with its constituent surface facing in the tire width direction, the power transmitting surface of the power transmitting coil 52 and the constituent surface of the power receiving coil 40 become parallel. This allows power to be supplied more efficiently, and ultimately achieves excellent power supply efficiency.

[0093] Figure 8 is a diagram showing the arrangement of the receiving coil 40, where (A) to (F) are examples showing a receiving coil 40 consisting of 2 sets, 3 sets, 4 sets, 5 sets, 6 sets, and 8 sets of receiving coil elements 40a, respectively, (G) is an example in which multiple receiving coil elements 40a are stacked in the tire radial direction, and (H) is an example in which some of the multiple receiving coil elements 40a extend at an angle with respect to the tire radial direction.

[0094] 8(A) to 8(H), the power receiving coil 40 may be formed from multiple power receiving coil elements 40a. At the tire cavity surface where the power receiving coil 40 is provided, deformation and release of the tire 10 are repeated while the tire 10 is rolling. If one power receiving coil 40 is provided around the entire circumference of the tire 10, the power receiving coil 40 will have portions that are distorted due to deformation while the tire 10 is rolling (near the contact area of ​​the tire 10) and portions that are not deformed (upper part of the tire 10), making the power receiving coil 40 more likely to peel off from the tire cavity surface. Therefore, by dividing the circumference of the tire into multiple regions and arranging power receiving coil elements 40a in each divided region, it is possible to prevent the power receiving coil 40 from peeling off from the tire inner circumferential surface.

[0095] FIG. 9 is a meridian cross section of a tire (half in the tire width direction) showing a power supply mode in which power is supplied from a power receiving coil 40 to an electronic device 46 attached to the tire cavity surface via a power line 44 in a tire 10.

[0096] As shown in FIG. 9 , the power receiving coil 40 is connected to a capacitor (not shown) as a resonant circuit, and supplies power to an electronic device 46 (sensor, signal processing circuit, communication circuit, etc.) attached to the tire cavity surface via a power line 44 attached to the tire cavity surface. The electronic device 46 has lower resistance to deformation than the power receiving coil 40, but is not affected by magnetic fields even when installed near the belt 20, which is a magnetic material. For this reason, the electronic device 46 is disposed on the tire cavity surface in the tire width direction region where the belt 20, which has high rigidity among the tire 10, is formed, and the power receiving coil 40 is disposed on the tire cavity surface in the sidewall portion B, where power supply efficiency can be increased, and the two are wired and connected by the power line 44. This allows the power received by the power receiving coil 40 to be supplied to the electronic device 46 with low loss and high power supply efficiency, while ensuring the durability of the electronic device 46. Furthermore, by arranging all of these components (the power receiving coil 40, the capacitor, the power line 44, and the electronic device 46) on the tire cavity surface, increases in the manufacturing costs and difficulty of manufacturing the tire 10 are suppressed.

[0097] 2. Second Embodiment A second embodiment of a tire according to the second invention (Basic Embodiment 2 and Additional Embodiments 15 to 18 shown below) will be described in detail below with reference to the drawings. Note that the second embodiment does not limit the present invention. Furthermore, the components of the second embodiment include those that are easily replaceable by a person skilled in the art, or those that are substantially identical. Furthermore, the second embodiment can be arbitrarily combined within the scope of obviousness to a person skilled in the art. The second embodiment can be arbitrarily combined with the first embodiment described above and the third embodiment described below.

[0098] [Basic Form 2] Components similar to those in the first embodiment are designated by similar reference numerals, and a description thereof will be omitted. Fig. 10 is a meridian cross section of a tire according to the second embodiment, showing one side in the tire width direction, with the tire equatorial plane CP as the reference. Note that Fig. 10 shows the tire portion on the side opposite the contact patch when the tire is mounted on a rim, the normal internal pressure is applied, and 80% of the normal load is applied (the same applies hereinafter to tire inventions unless otherwise noted).

[0099] 10 , a tire 10A according to the second embodiment has, from the inner side to the outer side in the tire radial direction, a bead portion A, a sidewall portion B, a shoulder portion C, and a tread portion D. An inner liner 12 exposed to the tire cavity surface is provided in the region from the bead portion A to the tread portion D, and a carcass 18 including a main portion 18a extending along the inner liner 12 and a folded portion 18b folded back around the bead core 14 and the bead filler 16 is provided on the opposite side of the inner liner 12 from the cavity surface, and a belt 20 (belt layers 20a, 20b) and a belt cover 22 (belt cover layers 22a, 22b, 22c) are sequentially provided radially outward of the carcass 18 in the tire radial direction in the tread portion D.

[0100] A rim cushion 24 is provided further outward in the tire width direction of the folded-up portion 18b of the carcass 18, which is provided outward in the tire width direction of the bead core 14 and the bead filler 16. A side tread 26, wing tips 28, and a cap tread 30 are provided, in this order, radially outward of the rim cushion 24. The tire according to the second embodiment is not limited to the example shown in Figure 10, and also includes, for example, a run-flat tire in which a run-flat liner is provided mainly in the sidewall portion B, outward in the tire width direction of the inner liner 12.

[0101] The bead core 14 is, for example, a ring-shaped reinforcing material formed by bundling cords, and may have a structure in which a plurality of bead wires made of steel cords or organic fiber cords are covered with rubber. The bead filler 16 is a member for increasing the rigidity of the bead portion A, and may have a substantially triangular shape as shown in Fig. 10, in which the tire width direction dimension at the tire radially inner end is substantially equal to the tire width direction dimension of the bead core 14 at the tire radially outer end, and the tire width direction dimension gradually decreases toward the tire radially outer side.

[0102] The carcass 18 is a component forming the framework of the tire 10A and is composed of at least one carcass layer (carcass ply), each of which is configured with a plurality of carcass cords coated with rubber. Generally, steel cords or organic fiber cords are used as the carcass cords. However, in the tire 10A according to this embodiment, as described below, it is preferable to use a non-magnetic material for the carcass cords in order to prevent a magnetic field generated in the sidewall portion B so as to penetrate the inner surface of the inner liner 12 substantially perpendicularly from being obstructed by a metal member. For example, organic fibers such as rayon, polyester, polyamide, and aramid can be used as the non-magnetic material.

[0103] The belt 20 is a reinforcing layer provided on the tire radially outer side of the carcass 18. It tightens the carcass 18 to increase the rigidity of the tread portion, improves steering stability, and reduces strain deformation and rolling resistance. The belt 20 can be composed of multiple belt layers (two belt layers 20a, 20b in the example shown in FIG. 10) laminated in the tire radial direction in the tread portion D. Each of the belt layers 20a, 20b has a configuration in which multiple belt cords are coated with rubber. Generally, steel cords or organic fiber cords are used as the belt cords. As the belt cords, magnetic materials such as steel cords can of course be used, but non-magnetic materials (including paramagnetic materials and diamagnetic materials) can also be used.

[0104] The belt cover 22A is a member that reinforces the tightening effect of the belt 20 on the carcass 18 and is a member that prevents deformation of the tread portion D due to centrifugal force generated, particularly when the vehicle is traveling at high speeds. The belt cover 22A can be composed of multiple belt cover layers (three belt cover layers 22a, 22b, and 22c in the example shown in FIG. 10 ) stacked in the tire radial direction on the tire radial outer side of the belt 20. Each of the belt cover layers 22a, 22b, and 22c has a configuration in which multiple cords are covered with rubber. Generally, steel cords or organic fiber cords are used as the cords for the belt cover layers. As for the cords, not only magnetic materials such as steel cords can be used, but also non-magnetic materials (including paramagnetic materials and diamagnetic materials) can be used.

[0105] The rim cushion 24 is provided in an area that contacts the rim flange of a wheel (not shown), and the side tread 26 is arranged to connect the rim cushion 24 and the tread portion D. The wing tips 28 are provided at the boundaries between the tread portions D and the side treads 26 on the left and right sides of the tire in a meridian cross section, and the cap tread 30 is formed on the surface of the tread portion D over the entire tire contact patch. A run-flat liner (not shown) is formed on the outer periphery of the inner liner 12 over at least the sidewall portion B (and possibly also the bead portion A and / or shoulder portion C). The rim cushion 24, side tread 26, wing tips 28, cap tread 30, and run-flat liner can all be made of conventional rubber materials depending on the required characteristics of each.

[0106] Assuming the presence of the components 12 to 30 of the tire 10A described above (and possibly a run-flat liner), the tire 10A according to the second embodiment includes, on its inner cavity surface, a power receiving coil 40 ( FIG. 10 ) that receives AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10A. The power receiving coil 40 may be provided in contact with the inner liner 12 or may be embedded in the inner liner 12. The power receiving coil 40 may also be provided so as to be fixed to the inner liner 12 via a fixing member other than rubber (for example, made of a non-magnetic material, but the fixing portion may be made of a rubber with a relatively high thermal conductivity, such as silicone rubber). Note that even when a run-flat liner is provided, the power receiving coil 40 may be provided on the inner circumferential side of the inner liner 12.

[0107] To achieve this type of power supply, in tire 10A according to the second embodiment, when viewed in a meridian cross section of the tire, the deflection index Kv / P (=Gr (mm)) obtained by dividing the tire's vertical spring constant Kv (N / mm) by the air pressure P (kPa) inside the tire, and the tire radial dimension CH (mm) from the tire's innermost position in the tire radial direction to the tire's outermost position in the tire radial direction satisfy 7≦CH / Gr≦95.

[0108] Here, based on the deflection δ50 when a load P50 that is 50% of the normal load is applied to tire 10A to which normal internal pressure is applied, and the deflection δ60 when a load P60 that is 60% of the normal load is applied to tire 10A to which normal internal pressure is applied, the vertical spring constant Kv (N / mm) of tire 10A is defined as (P60-P50) / (δ60-δ50).

[0109] As described above, conventionally, the power receiving coil is usually attached to a metal rim, which tends to affect the AC magnetic field and reduce the power that the power receiving coil can receive (see Patent Document 1, Figure 1). On the other hand, if the power receiving coil is placed away from the metal rim, the power supply efficiency improves, but it becomes difficult to dissipate the heat generated by the power receiving coil.

[0110] Therefore, the inventors of the present invention conducted extensive research to locate the power receiving coil in a tire component other than a metal member and with as large a surface area (i.e., an area for dissipating heat) as possible. As a result, the inventors focused on locating the power receiving coil in an inner liner formed on the inner circumferential side of the carcass, and discovered that by appropriately adjusting the ratio Gr / CH of the tire deflection index Gr (mm) to the tire radial dimension CH (mm) shown in Figure 10, a good fixing state of the power receiving coil at the location where the power receiving coil is located can be achieved, thereby achieving excellent power supply efficiency. The specific reasons for setting the upper and lower limits of the ratio Gr / CH are as follows:

[0111] That is, if the tire 10A is allowed to roll for a long period of time or if the tire 10A is allowed to roll under conditions of extreme temperature changes, the internal pressure of the tire 10A may decrease. This decrease in internal pressure may increase deformation of the tire 10A, which in turn may increase deformation of the power receiving coil 40 provided on the inner surface of the tire 10A. In light of these circumstances, the inventors focused on CH / Gr, a parameter related to deformation of the power receiving coil 40, and discovered that if the value of this parameter is 95 or less, the rigidity of the tire 10A does not become excessively small, the power receiving coil 40 does not deform, and excellent power supply can be achieved.

[0112] The inventors also found that if the value of this parameter is 7 or greater, the rigidity of the tire 10A will not become excessively large, and as a result, the impact that the receiving coil 40 receives while the tire 10A is running will not become excessively large, thereby achieving excellent durability in the tire 10A.

[0113] Based on the above findings, in the tire 10A according to the second embodiment, the value of the parameter CH / Gr is set to be equal to or greater than 7 and equal to or less than 95, as shown in FIG. 10 . As a result, in the tire 10A according to the second embodiment, the rigidity of the tire 10A does not become excessively small and the power receiving coil 40 does not deform excessively based on the range of the upper limit value of the parameter, thereby improving power supply efficiency. Furthermore, in the tire 10A according to the second embodiment, excellent durability performance can also be achieved based on the range of the lower limit value of the parameter. Note that the value of the parameter CH / Gr is preferably equal to or greater than 8 and equal to or less than 92, and extremely preferably equal to or greater than 9 and equal to or less than 90.

[0114] Furthermore, in basic form 2, the inventors have intensively studied, as an optional matter, at what position the power receiving coil 40 provided on the inner cavity surface of the tire 10A should be formed relative to the power transmitting coil (not shown) provided outside the tire 10A in order to further improve the power supply efficiency.

[0115] First, the inventors focused on the multiple line segments in Figure 10 that reach each point (starting point) on the tire cavity surface (the same applies when a run-flat liner is present) to each point (ending point) on the tire outer surface in the shortest distance, extracted a region consisting of multiple line segments that do not include the belt 20, and positioned the receiving coil 40 so that it does not deviate from the tire cavity surface included in this region, and discovered that by doing so, most of the magnetic field generated between the two coils will not be blocked by the belt 20, which may contain magnetic material.

[0116] Next, in light of the fact that the above finding is for defining the radially outer end of the installation area of ​​the power receiving coil 40, the inventors further studied how to also define the radially inner end of this installation area. As a result, the inventors focused on the bead core 14, which may be made of a metal member, and discovered that by extracting an area consisting of multiple line segments that do not include the bead core 14 from among the above line segments, and arranging the power receiving coil 40 so that it does not deviate from the tire cavity surface included in this area, most of the magnetic field generated between the two coils will not be blocked by the bead core 14, which may contain a magnetic material.

[0117] Based on the above findings, in the tire 10A according to the second embodiment, as shown in FIG. 10 , if the power receiving coil 40 is provided in a tire radial region WH extending from the outermost position of the bead core 14 in the tire radial direction to the innermost position of the belt 20 in the tire radial direction (hereinafter, this may be referred to as the "tire radial power receiving region WH"), power supply efficiency can be further improved because an excessive number of components of the tire 10A that may contain magnetic material are not provided between the power transmitting coil and the power receiving coil 40.

[0118] (Additional Mode 15) In Basic Mode 2, it is preferable that the relationship between the tire radial direction dimension CH (mm) from the tire radially innermost position of the tire 10A shown in Fig. 10 to the tire radially outermost position of the power receiving coil 40, the tire radial direction length SH (mm), and the tire aspect ratio r (0 < r ≦ 1) satisfy the following (Additional Mode 15). Note that the tire radial direction dimension CH (mm) is a value measured by CT scanning an image of the tire 10A shown in Fig. 10 mounted on a rim, pressurized to a normal internal pressure, and not in contact with the ground.

[0119] Generally, even if the above parameter (CH / SH) is constant, the rigidity of the sidewall portion B varies depending on the aspect ratio r (tire cross-sectional height / tire cross-sectional width), and therefore the degree of deformation of the power receiving coil 40 also varies, so the aspect ratio r is an important factor in power supply.

[0120] When the aspect ratio r is relatively small, i.e., when the tire section height relative to the tire section width is relatively small, the deflection of the sidewall portion B is relatively small under normal load and normal internal pressure, whereas when the aspect ratio r is relatively large, i.e., when the tire section height relative to the tire section width is relatively large, the deflection of the sidewall portion B under the same conditions is relatively large. In other words, when the aspect ratio r is relatively small, the rigidity of the sidewall portion B is relatively high, and when the aspect ratio r is relatively large, the rigidity of the sidewall portion B is relatively low.

[0121] Therefore, based on the knowledge that the suitable range of the installation position of the receiving coil 40 when taking into account the rigidity of the sidewall portion B differs depending on the flatness r, the inventors conducted various experiments and obtained the range of the above inequality.

[0122] Specifically, by setting the parameter (CH / SH) to (-0.3r+0.6) or less, the deflection that the power receiving coil 40 receives when the tire 10A rolls is not excessively large, thereby improving the durability of the power receiving coil 40 and, ultimately, the durability of the tire 10A. Note that the parameter (CH / SH) is more preferably (-0.3r+0.58) or less, and extremely preferably (-0.3r+0.56) or less.

[0123] Next, the inventors further studied a more preferable attachment position of the power receiving coil 40 on the tire cavity surface, and as a result, the inventors discovered that power supply efficiency can be further improved by not making the thickness of the rubber layer (rim cushion 24 and side tread 26) of the tire 10A excessively thick at the attachment position (tire radial position) of the power receiving coil 40 and by not positioning the power receiving coil 40 in the tire radial direction too close to the bead core 14, which may include a metal member.

[0124] Specifically, by setting the parameter (CH / SH) to (-0.1r+0.17) or greater, the power receiving coil 40 does not get too close to the bead core 14 shown in Figure 10. This prevents the bead core 14 from blocking the magnetic field, and prevents the rubber layers (rim cushion 24 and side tread 26) from becoming excessively thick at the tire radial position where the power receiving coil 40 is attached, thereby achieving even better power supply efficiency. Note that the parameter (CH / SH) is more preferably (-0.1r+0.19) or greater, and extremely preferably (-0.1r+0.21) or greater.

[0125] (Additional Form 16) In Basic Form 2 or a form obtained by adding Additional Form 15 to Basic Form 2, it is preferable that the relationship between the tire radial direction dimension DH from the tire radially outermost position of the power receiving coil 40 to the tire radially innermost position of the belt 20 shown in FIG. 10 (hereinafter sometimes referred to as the "dimension DH from the power receiving coil to the belt"), the tire radial direction region WH from the tire radially outermost position of the bead core 14 to the tire radially innermost position of the belt 20, and the sum [ΣGiHi] of the products of the thickness Gi of the rubber layer disposed on the tire widthwise outer side of the carcass 18 and the hardness Hi of this rubber layer on a line drawn in the tire width direction from the tire radial center position of the power receiving coil 40 satisfies 80≦(DH / WH)×[ΣGiHi]≦800 (Additional Form 16).

[0126] 10, the rubber layer disposed on the outer side of the carcass 18 in the tire width direction includes the bead filler 16, rim cushion 24, and side tread 26. Note that this rubber layer also includes a second filler (not shown) located on the outer side of the folded-up portion 18b of the carcass 18 in the tire width direction and on the inner side of the rim cushion 24 and side tread 26 in the tire width direction.

[0127] The total thickness of these rubber layers is preferably 4 mm or more in consideration of tire rigidity, and 15 mm or less in consideration of power supply efficiency. The hardness of each rubber layer can be 50 to 98 degrees (measured, for example, with a durometer type A based on JIS-K6253).

[0128] The present inventors have conducted extensive research into further suppressing deformation of the power receiving coil 40 shown in Fig. 10 during tire rotation and further increasing the durability of the power receiving coil 40. As a result, the present inventors have discovered that it is essential to further increase the rigidity of the tire 10A at a position in the tire radial direction on the tire cavity surface where the power receiving coil 40 shown in Fig. 10 is attached.

[0129] That is, the inventors have discovered that at the tire radial position where the power receiving coil 40 is attached (for example, the center position of the power receiving coil 40 in the tire radial direction), the product of the tire width direction dimension Gi (where i is an integer of 1 or more, the same applies below) and hardness Hi of each rubber layer present on a line drawn from this tire radial center position in the tire width direction is calculated, and the products G1H1, G2H2, G3H3, ... calculated for all rubber layers are further added together to calculate the sum ΣGiHi, and this sum is considered to be the tire rigidity at the attachment position of the power receiving coil 40, and the minimum value thereof is found.

[0130] However, the tire stiffness at the attachment position of the power receiving coil 40 is also affected by the relationship between the power receiving area WH in the tire radial direction and the area DH from the power receiving coil 40 to the belt 20, as shown in Figure 10. The reason for this is as follows.

[0131] Typically, due to the influence of rubber thickness and rubber hardness, tire rigidity tends to be higher the closer to the bead core 14 shown in Figure 10, and lower the farther from the bead portion A in the region from sidewall portion B to shoulder portion C. Therefore, at installation positions of the power receiving coil 40 where the ratio DH / WH of region DH to region WH is small, it is necessary to increase the rubber thickness and rubber hardness to compensate for the lack of rigidity. On the other hand, at installation positions of the power receiving coil 40 where the ratio DH / WH is large, a certain degree of rigidity is already ensured, so there is little need to further increase the rigidity by increasing the rubber thickness and rubber hardness.

[0132] Based on the above findings, the ratio DH / WH is considered as an adjustment parameter, and the product obtained by multiplying the sum ΣGiHi by the ratio DH / WH, which is the adjustment parameter, is ultimately considered to be the tire stiffness at the attachment position of the power receiving coil 40, and its minimum value is determined.

[0133] Specifically, by setting (DH / WH)×[ΣGiHi] to 80 or more, the tire rigidity at the attachment position of the power receiving coil 40 can be further increased, thereby further suppressing deformation of the power receiving coil 40 when the tire rolls, and ultimately further increasing the durability of the power receiving coil 40. It is more preferable to set (DH / WH)×[ΣGiHi] to 100 or more, and extremely preferable to set it to 120 or more.

[0134] Next, the inventors focused on the fact that the power receiving coil 40 shown in Fig. 10 generates heat when the tire rotates, and conducted extensive research into suitable heat dissipation properties of the power receiving coil 40. As a result, through various experiments, the inventors discovered that the heat dissipation properties of the power receiving coil 40 when the tire rotates can be improved by setting an upper limit value for the above-mentioned (DH / WH) x [ΣGiHi].

[0135] Specifically, by setting (DH / WH)×[ΣGiHi] to 800 or less, heat generation by the power receiving coil 40 can be suppressed, and heat dissipation can be improved. Setting (DH / WH)×[ΣGiHi] to 760 or less is more preferable, and setting it to 720 or less is extremely preferable.

[0136] (Additional Form 17) In Basic Form 2 or a form in which Basic Form 2 is combined with at least one of Additional Forms 15 and 16, it is preferable that the folded end 18c of the carcass 18 shown in Figure 10 is located on the tire radial outside or tire radial inside of the tire radial region CW in which the receiving coil 40 is provided (Additional Form 17).

[0137] Generally, the stiffness changes locally near the turned-up end 18c of the carcass 18. As a result, stress may concentrate between the turned-up end 18c and the other rubber layers surrounding it when the tire rolls. Installing the power receiving coil 40 near the turned-up end 18c where stress may concentrate increases the risk of the power receiving coil 40 deforming when the tire rolls, and is therefore not preferable.

[0138] Based on this knowledge, in the second embodiment, the folded end 18c of the carcass 18 shown in Fig. 10 is positioned on the tire radial outer side or tire radial inner side of the tire radial region CW in which the power receiving coil 40 is provided. This makes it possible to suppress deformation of the power receiving coil 40 during tire rotation, and ultimately to further increase the durability of the power receiving coil 40.

[0139] In the above-described additional form 4, it is further preferable that, taking into consideration the average tire thickness A in the tire radial region CW where the power receiving coil 40 shown in Fig. 10 is provided, the folded end 18c of the carcass 18 is positioned on the tire radial outer side or the tire radial inner side of a region Ca obtained by adding the same tire radial dimension A as the average tire thickness A to the tire radial upper and lower sides of the tire radial region CW (additional form 4'). Here, the average tire thickness refers to the tire thickness at a radially middle position of the tire radial region CW.

[0140] As described above, in the second embodiment, the folded-up end 18c of the carcass 18 is positioned on the tire radially outer side or the tire radially inner side of the region Ca, which is obtained by adding the tire radial dimension A that is the same as the average tire thickness A to the tire radially upper and lower sides of the tire radial region CW. This allows the power receiving coil 40 to be installed away from the boundary between the folded-up end 18c and the rubber layer surrounding the folded-up end 18c, where stress concentration occurs when the tire rolls. As a result, deformation of the power receiving coil 40 when the tire rolls can be more reliably prevented, and ultimately, an extremely high level of durability can be achieved for the power receiving coil 40.

[0141] 11 is a side view of the tire 10A shown in FIG. 10 mounted on a rim and pressurized to a normal internal pressure, where (a) shows the tire not in contact with the ground (i.e., no load) and (b) shows the tire in contact with the ground (when a load of 80% of the normal load is applied). In FIG. 10, CH denotes the radial dimension of the tire 10A from the radially innermost position of the tire 10A to the radially outermost position of the power receiving coil.

[0142] In Basic Configuration 2 or a configuration in which at least one of Additional Configurations 15 to 17 is added to Basic Configuration 2, it is preferable that the ratio Rc(CHD / CHI) of the tire radial direction dimension CHD (mm) from the tire radially innermost position to the tire radially outermost position of the power receiving coil in the region immediately above the ground contact state of the tire 10A when the tire is in contact with the ground ( FIG. 11(b) ) shown in FIG. 11 to the tire radial direction dimension CHI (mm) from the tire radially innermost position to the tire radially outermost position of the power receiving coil when the tire is not in contact with the ground ( FIG. 11(a) ) and the ratio Rs(SHD / SHI) of the tire radial direction length SHD (mm) in the region immediately above the ground contact state of the tire 10A when the tire is in contact with the ground ( FIG. 11(b) ) to the tire radial direction length SHI (mm) when the tire is not in contact with the ground ( FIG. 11(a) ) satisfy 1.05<Rc / Rs<1.35 (Additional Configuration 18).

[0143] The tire radial dimensions CHD (mm) and CHI (mm) are both dimensions related to the region indicated by the tire radial dimension CH shown in Fig. 4. The region directly above the ground contact area refers to a region included in a plane that includes the tire rotation axis and extends perpendicular to the ground contact area from the tire rotation axis to the ground contact area (actually, it corresponds to the tire meridian section).

[0144] The inventors further conducted extensive research into the requirements for reducing deformation of the power receiving coil 40 in response to deflection in the tire radial direction when the tire 10A shown in Figure 10 is mounted on a rim, pressurized to the normal internal pressure, and subjected to a load of 80% of the normal load.

[0145] First of all, when a load of 80% of the normal load is applied, not only does the tire radial length SH (mm) (see FIG. 10) decrease as shown in FIG. 11 , but the tire radial dimension CH (mm) (the tire radial dimension from the tire radially innermost position of the tire 10A to the tire radially outermost position of the power receiving coil 40, see FIG. 10 ) also decreases. Here, if the decrease in the tire radial dimension CH is significantly greater than the decrease in the tire radial length SH when a load of 80% of the normal load is applied, a sufficient tire radial region for attaching the power receiving coil 40 may not be secured, and the power receiving coil 40 may deform when the tire rotates.

[0146] Based on this knowledge, the inventors, as a result of various experiments, decided to set an upper limit for the parameter Rc / Rs. Specifically, by setting the parameter Rc / Rs to less than 1.35, the decrease in the tire radial dimension CH is not excessively large relative to the decrease in the tire radial length SH, and thus a sufficient tire radial region in which the power receiving coil 40 can be attached is ensured (i.e., in the case of passenger car tires, the tire radial dimension is in the range of 20 mm to 55 mm), thereby further suppressing deformation of the power receiving coil 40 during tire rotation. It is more preferable that the parameter Rc / Rs be 1.33 or less, and extremely preferable that it be 1.30 or less.

[0147] As a result of conducting numerous experiments using various tire sizes, the inventors have concluded that the parameter Rc / Rs is almost never equal to or less than 1.05, and have therefore decided to set the parameter Rc / Rs to be greater than 1.05.

[0148] <Other Aspects of Tire and Wireless Power Supply System> The components of the tire 10A shown in FIG. 10 are: the inner liner 12; the carbon content of the inner liner 12 is 45 to 75 parts by mass (mass parts where the rubber is 100; the same applies below); the side tread; the rim cushion; the bead filler 16; the carbon content of the covering rubber of the carcass 18; and the run-flat liner; each of these carbon content amounts is preferably 40 to 80 parts by mass. The carbon content of the covering rubber of the carcass 18 is 35 to 70 parts by mass. By adopting these respective carbon content amounts, it is possible to achieve the desired physical properties (hardness, elastic modulus, etc.) and heat dissipation in each rubber layer while also achieving the excellent power supply efficiency described above. Note that, typically, adjusting the carbon content is effective for improving the heat dissipation of the rubber, and is most preferred because it is easy to achieve compatibility with the rubber properties required for the tire.

[0149] 3. Third Embodiment A third embodiment of a tire according to the third invention (Basic Embodiment 3 and Additional Embodiments 19 to 30 shown below) will now be described in detail with reference to the drawings. Note that the third embodiment does not limit the present invention. Furthermore, the components of the third embodiment include those that are easily replaceable by a person skilled in the art, or those that are substantially identical. Furthermore, the third embodiment can be arbitrarily combined within the scope of what is obvious to a person skilled in the art. The third embodiment can be arbitrarily combined with the first embodiment and the second embodiment described above.

[0150] [Basic Form 3] Components similar to those in the first embodiment are given the same reference numerals, and a description thereof will be omitted. A basic form of a tire according to a third embodiment will be described below. Fig. 12 is a meridian cross section of the tire according to the third embodiment. This figure shows the tire portion on the side opposite the contact patch when the tire is mounted on a rim, the normal internal pressure is applied, and a load of 80% of the normal load is applied (the same applies hereinafter to tire inventions).

[0151] 12 , a tire 10B according to the third embodiment has, from the inner side to the outer side in the tire radial direction, a bead portion A, a sidewall portion B, a shoulder portion C, and a tread portion D. An inner liner 12 exposed to the tire cavity surface is provided in the region from the bead portion A to the tread portion D, and a carcass 18 including a main body portion 18a extending along the inner liner 12 and a folded portion 18b folded back around the bead core 14 and the bead filler 16 is provided on the opposite side of the inner liner 12 from the tire cavity surface, and a belt 20 (belt layers 20a, 20b) and a belt cover 22 (belt cover layers 22a, 22b) are sequentially provided radially outward of the carcass 18 in the tire radial direction in the tread portion D.

[0152] A rim cushion 24 is provided further outward of the folded-up portion 18b of the carcass 18, which is provided outward in the tire width direction of the bead core 14 and the bead filler 16. A side tread 26 and a cap tread 30 are provided in this order radially outward of the rim cushion 24.

[0153] In the tire 10B configured as described above, the inner liner 12 is a layer for blocking gas that comes into contact with the tire cavity surface. The inner liner 12 can be configured with a single inner liner layer, or can be configured with multiple inner liner layers stacked in the tire radial direction at the tire equatorial plane CP. The inner liner 12 includes at least one layer made of rubber or resin with low air permeability, and can include an adhesive layer at least in the portion that contacts the carcass 18 as other layers.

[0154] The bead core 14 is, for example, a ring-shaped reinforcing material formed by bundling cords, and may have a structure in which a plurality of bead wires made of steel cords or organic fiber cords are covered with rubber. The bead filler 16 is a member for increasing the rigidity of the bead portion A, and may have a substantially triangular shape as shown in Fig. 12, in which the tire width direction dimension at the tire radially inner end is substantially equal to the tire width direction dimension of the bead core 14 at the tire radially outer end, and the tire width direction dimension gradually decreases toward the tire radially outer side.

[0155] The carcass 18 is a component forming the framework of the tire 10B and is composed of at least one carcass layer (carcass ply), each of which has a configuration in which a plurality of carcass cords are coated with rubber. Generally, organic fiber cords are used as the carcass cords. However, in the tire 10B according to this embodiment, as described below, it is preferable to use a non-magnetic material for the carcass cords in order to prevent a magnetic field generated in the sidewall portion B so as to penetrate the tire cavity surface of the inner liner 12 substantially perpendicularly from being obstructed by a metal member. For example, resin fibers such as rayon, polyester, polyamide, and aramid can be used as the non-magnetic material.

[0156] The belt 20 is a reinforcing layer provided on the radially outer side of the carcass 18, and tightens the carcass 18 to increase the rigidity of the tread portion, improving steering stability, and reducing strain deformation and rolling resistance. The belt 20 can be composed of multiple belt layers (two belt layers 20a, 20b in the example shown in FIG. 12) laminated in the radial direction of the tire in the tread portion D. Each of the belt layers 20a, 20b has a configuration in which multiple steel cords are coated with rubber.

[0157] The belt cover 22 is a member that reinforces the tightening effect of the belt 20 on the carcass 18 and is a member that prevents deformation of the tread portion D due to centrifugal force generated, particularly when the vehicle is traveling at high speeds. The belt cover 22 can be composed of multiple belt cover layers (two belt cover layers 22a, 22b in the example shown in FIG. 12 ) stacked in the tire radial direction on the tire radial outer side of the belt 20. Each belt cover layer 22a, 22b is configured by covering multiple cords with rubber. Generally, organic fiber cords are used as the cords used in the belt cover layers. The tire 10B includes a second carcass 29 inside the carcass 18. The second carcass 29 includes a main body portion 29a extending along the inner liner 12 and a folded portion 29b folded around the bead core 14 and the bead filler 16. Furthermore, a steel reinforcement 33 is provided as a reinforcing layer between the folded portion 29b and the bead filler 16. The provision of the steel reinforcement 33 can appropriately improve the rigidity of the sidewall portion B. The steel reinforcement 33 has a configuration in which a plurality of steel cords are covered with rubber.

[0158] The rim cushion 24 is provided in an area that contacts the rim flange 8 of the rim 6, and the side tread 26 is arranged to connect the rim cushion 24 and the tread portion D. The cap tread 30 is formed on a tread surface 34, which is the surface of the tread portion D. A plurality of circumferential main grooves 36 are provided on the tread surface 34. A pair of outer circumferential main grooves 38 located on the outermost sides in the tire width direction form the boundary, and a center land portion 35 is defined and formed on the inner side in the tire width direction of the outer circumferential main grooves 38, and shoulder land portions 39 are defined and formed on the outer side in the tire width direction of the outer circumferential main grooves 38. The rim cushion 24, side tread 26, and cap tread 30 can all be made of conventional rubber materials depending on the required characteristics of each.

[0159] Assuming the presence of the components 12 to 38 of the tire 10B described above, the tire 10B according to the third embodiment includes a power receiving coil 40 ( FIG. 12 ) on, for example, the tire cavity surface, that receives AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10B. The power receiving coil 40 may be provided in contact with the inner liner 12, or may be embedded in the inner liner 12. The power receiving coil 40 may also be provided so as to be fixed to the inner liner 12 via a fixing member other than rubber (for example, made of a non-magnetic material, although the fixing portion may be made of a rubber with a relatively high thermal conductivity, such as silicone rubber) ( FIG. 12 ).

[0160] As shown in FIG. 13 , the reinforcing layer 11 of the tire 10 according to the third embodiment has an area ratio of the portion excluding the steel cords to the area of ​​the reinforcing layer 11 in a front view of 0.1 to 0.7.

[0161] As described above, the reinforcing layer 11 is the belt 20 or the steel reinforcement 33. In the following description, when the belt 20 and the steel reinforcement 33 are not distinguished, they will be collectively referred to as the reinforcing layer 11. The reinforcing layer 11 is formed of a plurality of steel cords. The steel cords may be solid wires made of a single filament or twisted wires made of a plurality of filaments. The reinforcing layer 11 shown in FIG. 13 is formed by stacking two reinforcing layers 11 in a direction perpendicular to the surface direction in a front view, i.e., in the thickness direction. When the reinforcing layer 11 is stacked in the thickness direction, the steel cords 13 are arranged in a lattice pattern. The reinforcing layer 11 formed by stacking two reinforcing layers 11 shown in FIG. 13 is applied to the belt 20. The reinforcing layer 11 is not limited to being used in a two-layered state, and may be used as a single layer. One reinforcing layer 11 is applied to the steel reinforcement 33.

[0162] The steel cords 13 of one of the overlapping reinforcing layers 11 are inclined at a certain angle from top to bottom to one side of the paper in Fig. 13 with respect to the vertical direction of the paper, and are arranged at a predetermined interval. The steel cords 13 of the other of the overlapping reinforcing layers 11 are inclined at a certain angle from top to bottom to the other side of the paper in Fig. 13 with respect to the vertical direction of the paper, and are arranged at a predetermined interval. Each reinforcing layer 11 is overlapped with the steel cords 13 arranged as described above, each coated with rubber. Because the steel cords 13 of the reinforcing layers 11 are covered with rubber, the steel cords 13 cannot or are difficult to see from the outside.

[0163] When the reinforcing layers 11 are overlapped in the plane direction, the rubber portions 15 between the steel cords 13 form a diamond shape when viewed in the thickness direction. That is, when viewed in the thickness direction, the two reinforcing layers 11 overlapped in the thickness direction are divided into the steel cord 13 portions and the rubber portions 15 between the steel cords 13. When the surface area of ​​the entire reinforcing layer is S and the surface area of ​​the rubber portions 15 between the steel cords 13 is SR, the ratio of the area SR of the portions other than the steel cords 13 to the area S of the reinforcing layer (area ratio: SR / S) is 0.1 or more and 0.7 or less, preferably 0.15 or more and 0.65 or less, and more preferably 0.2 or more and 0.6 or less.

[0164] The area ratio can be measured as follows. First, a 25 mm x 25 mm piece of reinforcing layer is cut out from the target tire to serve as a sample. At this time, the splice portion where the reinforcing layer overlaps in the thickness direction is avoided. Next, an X-ray photograph is taken in the thickness direction of the sample. The photograph is binarized, and the area of ​​the transparent region (white portion) in an arbitrary 10 mm x 10 mm region is taken as SR (surface area of ​​the rubber portion). The area of ​​the arbitrary region is taken as 100 mm. ２ The value of SR / S is calculated with S (the surface area of ​​the entire reinforcing layer) as the area ratio.

[0165] (Operation) When AC power is supplied, the power transmission coil provided outside the tire generates a magnetic field having a specific frequency. The magnetic field generated by the power transmission coil passes from the tire outer surface between the steel cords 13 of the reinforcing layer 11 and reaches the power receiving coil 40. The magnetic field causes a current to flow through the power receiving coil 40, generating electric power. By having the area ratio (SR / S) of 0.1 or greater and 0.7 or less, the reinforcing layer 11 exhibits the effect of reinforcing the tire structure while suppressing the steel cords 13 from blocking the magnetic field. Therefore, tire 10B can suppress a decrease in power supply efficiency.

[0166] If the area ratio (SR / S) is less than 0.1, the area of ​​the rubber portion 15 is too small, so the magnetic field that reaches the reinforcing layer 11 is blocked by the steel cords 13, which may reduce the power supply efficiency. On the other hand, if the area ratio (SR / S) is more than 0.7, the proportion of the steel cords 13 is too small, so the effect of reinforcing the structure of the tire 10B may be reduced. In the above-mentioned Basic Form 3, two reinforcing layers 11 are described as being stacked, but the present invention is not limited to this. The reinforcing layer 11 may be one layer, or three or more layers.

[0167] [Additional Form 19] In Basic Form 3, the reinforcing layer 11 is a belt 20 provided in the tread portion D, and the belt 20 has an area ratio (SR / S) of the portion excluding the steel cords 13 to the area of ​​the belt 20 in a front view of 0.1 or more and 0.5 or less (Additional Form 19), and more preferably 0.15 or more and 0.45 or less.

[0168] The tire 10B has a power receiving coil 40 provided at a position where it is susceptible to the magnetic field generated by a power transmitting coil provided on the tire radially outer side. The power receiving coil 40 may be provided at position 40D on the tire inner surface (hereinafter also referred to as the "inner tread surface") opposite the tread surface 34 (FIG. 12). The power receiving coil 40 provided at position 40D may have a conductor wound in a cylindrical shape centered on the tire rotation axis so that the conductor is aligned in the tire width direction along the inner tread surface. The power transmitting coil provided on the tire radially outer side generates a magnetic field when AC power is supplied. The magnetic field generated by the power transmitting coil passes from the tire radially outer side between the steel cords 13 of the belt 20 and reaches the power receiving coil 40 provided at position 40D. The magnetic field causes a current to flow in the power receiving coil 40, generating electric power.

[0169] The belt 20 is a reinforcing layer 11 including the steel cords 13, and by having the area ratio (SR / S) within the above range, the rigidity of the tread portion of the tire 10B is increased, preventing separation between the carcass 18 and the cap tread 30, while suppressing the steel cords 13 from blocking the magnetic field. Therefore, the tire 10B can more reliably suppress a decrease in power supply efficiency.

[0170] The power receiving coil 40 may be provided at position 40F in Fig. 14. The power receiving coil 40 provided at position 40F may have its conductor wound in a spiral shape around the tire rotation axis so that the conductor is aligned in the tire radial direction.

[0171] [Additional Form 20] In Basic Form 3, the reinforcing layer 11 is provided in the sidewall portion B, and the area ratio (SR / S) of the portion excluding the steel cords 13 to the area of ​​the reinforcing layer 11 in a front view is preferably 0.3 or more and 0.7 or less (Additional Form 20), and more preferably 0.35 or more and 0.65 or less.

[0172] In additional embodiment 20, the reinforcing layer 11 is provided in a region in the tire radial direction from the end of the belt in the tire width direction to the outermost position in the tire radial direction of the bead core 14. The reinforcing layer 11 according to additional embodiment 20 is a steel reinforcement 33 provided in the region. The tire 10B also includes a carcass layer in the sidewall portion B. The area of ​​the reinforcing layer 11 in a front view is the surface area of ​​the reinforcing layer 11, and is the area of ​​the face that appears when viewed from a direction perpendicular to a plane including the steel cords included in the reinforcing layer 11. It is preferable that the area ratio (SR / S) of the steel reinforcement 33 is within the above range.

[0173] The tire 10B has a power receiving coil 40 provided at a position that is susceptible to the magnetic field generated by a power transmitting coil provided on the outer side in the tire width direction. The power receiving coil 40 may be provided at position 40E on the tire inner surface opposite the tire side surface ( FIG. 12 ). The power transmitting coil provided on the outer side in the tire width direction generates a magnetic field when supplied with an AC voltage. The magnetic field generated by the power transmitting coil passes from the outer side in the tire width direction between the steel cords 13 in the sidewall portion B and reaches the power receiving coil 40 provided at position 40E. The magnetic field causes a current to flow in the power receiving coil 40, generating electric power.

[0174] The steel reinforcements 33 are reinforcing layers 11, and by having the area ratio (SR / S) within the above range, the rigidity of the sidewall portion B is appropriately improved while the steel cords 13 are prevented from blocking the magnetic field. Therefore, the tire 10B can more reliably prevent a decrease in power supply efficiency.

[0175] [Additional Form 21] In Basic Form 3 or a form obtained by adding Additional Form 19 or 20 to Basic Form 3, the spacing WG between adjacent steel cords 13 included in the reinforcing layer 11 is preferably 0.4 mm or more and 2.4 mm or less (Additional Form 21), and more preferably 0.5 mm or more and 2.2 mm or less.

[0176] 13 , the spacing WG between adjacent steel cords 13 is the distance between the opposing surfaces of the steel cords 13 in the reinforcing layer 11. When the spacing WG between adjacent steel cords 13 is 0.4 mm or more, the reinforcing layer 11 can more reliably suppress blocking of the magnetic field. When the spacing WG between adjacent steel cords 13 is 2.4 mm or less, the reinforcing layer 11 can more reliably reinforce the tire structure. Therefore, tire 10B can suppress a decrease in power supply efficiency even when the reinforcing layer 11 is present between the power transmitting coil and the power receiving coil 40.

[0177] The spacing WG between the steel cords 13 is a value measured between the steel cords 13 closest to the power receiving coil 40. For example, if the reinforcing layer 11 is the belt 20 and is made up of two reinforcing layers 11 stacked on top of each other, the spacing between the steel cords 13 closest to the power receiving coil 40 in the reinforcing layer 11 on the inner side in the tire radial direction is measured. The spacing between the steel cords 13 is measured by disassembling the target tire.

[0178] [Additional Configuration 22] In Basic Configuration 3 or a configuration in which any one of Additional Configurations 19 to 21 is added to Basic Configuration 3, the cross-sectional circumferential length of the steel cord 13 perpendicular to the longitudinal direction is preferably 1.5 mm or more and 7.0 mm or less (Additional Configuration 22), and more preferably 1.8 mm or more and 7.0 mm or less.

[0179] When the steel cord 13 is a single wire consisting of one filament, the cross-sectional perimeter perpendicular to the longitudinal direction of the steel cord 13 is the perimeter of the cross section of one filament perpendicular to the longitudinal direction. When the steel cord 13 is a twisted wire consisting of multiple filaments, the cross-sectional perimeter perpendicular to the longitudinal direction of the steel cord 13 is the sum of the perimeters of the cross sections of each filament perpendicular to the longitudinal direction. The steel cord 13 is preferably a twisted wire consisting of multiple filaments, and the cross-sectional area of ​​the cross section perpendicular to the longitudinal direction is 0.1 mm ２ More than 0.7 mm ２ Preferably, it is 0.12 mm or less. ２ More than 0.65 mm ２More preferably, it is:

[0180] When the steel cords 13 in the reinforcing layer 11 are subjected to a magnetic field, eddy currents are generated within the steel cords 13, which in turn generates heat.

[0181] The tire 10B has a cross-sectional circumference orthogonal to the longitudinal direction of the steel cords 13 within the above range, thereby providing a predetermined contact area with the rubber covering the steel cords 13. This allows efficient heat dissipation from the steel cords 13 to the rubber. If the cross-sectional circumference is too small, heat may not be dissipated sufficiently, whereas if it is too large, the thickness of the reinforcing layer may become excessive, potentially increasing the rolling resistance and mass of the tire.

[0182] [Additional Configuration 23] In Basic Configuration 3 or a configuration in which Basic Configuration 3 is combined with any one of Additional Configurations 19 to 22, it is preferable that the steel cord 13 be made of 1 to 6 filaments (Additional Configuration 23).

[0183] The filaments preferably have a diameter of 0.15 mm to 0.5 mm, more preferably 0.2 mm to 0.4 mm. The steel cord 13 preferably consists of six or fewer filaments, and more preferably three (FIG. 15(A)), four (FIG. 15(B)), or six (FIGS. 15(C) and (D)) filaments, as shown in FIG. 15.

[0184] When the steel cords 13 in the reinforcing layer 11 are subjected to a magnetic field, eddy currents are generated within the steel cords 13. Eddy currents generated when subjected to a high-frequency magnetic field occur in a region up to a specific skin depth of the magnetic field. Therefore, if the steel cords 13 are twisted wires made of multiple filaments, the surface area of ​​the steel cords tends to increase, and losses due to eddy currents tend to increase. Here, the nominal depth of the magnetic field refers to the penetration depth of the magnetic field from the surface of the material until the magnetic field strength of the high-frequency external excitation magnetic field attenuates to 1 / e (e: base of the natural logarithm) of the magnetic field strength at the surface due to eddy currents from the surface of the material.

[0185] In contrast, the steel cord 13 is made up of six or fewer filaments, thereby minimizing eddy current loss. Therefore, the tire 10B includes the reinforcing layer 11 formed using the steel cord 13 made up of six or fewer filaments, thereby suppressing a decrease in power supply efficiency.

[0186] [Additional Form 24] In Basic Form 3 or a form in which Basic Form 3 is combined with any one of Additional Forms 19 to 23, it is preferable that the winding width of the receiving coil 40 be greater than the spacing between adjacent steel cords 13 contained in the reinforcing layer 11 (Additional Form 24).

[0187] 16 , the conductors of the power receiving coil 40 are aligned along the surface of the reinforcing layer 11. The winding width WC refers to the length in the direction perpendicular to the longitudinal direction of the conductors of the power receiving coil 40, in which the conductors are aligned.

[0188] By making the winding width WC of the power receiving coil 40 larger than the spacing WG between the steel cords 13, the magnetic field that passes through the reinforcing layer 11 can sufficiently interlink with the power receiving coil 40, thereby suppressing a decrease in power supply efficiency. The ratio of the winding width WC to the spacing WG between the steel cords 13, i.e., the value obtained by dividing the winding width WC by the spacing WG between the steel cords 13 (winding width WC / spacing WG), is preferably 1.1 or greater and 30 or less. A value of 1.1 or greater allows the magnetic field to sufficiently interlink with the power receiving coil 40, while a value of 30 or less prevents the power receiving coil 40 from becoming too large. Note that the power receiving coil 40 may have one or more windings. When the number of windings is one, the winding width WC is the wire diameter of the winding.

[0189] [Additional Form 25] In Basic Form 3 or a form in which Basic Form 3 is combined with any one of Additional Forms 19 to 24, it is preferable that the distance WD (m) between the reinforcing layer 11 and the receiving coil 40 and the frequency f (kHz) of the supplied magnetic field satisfy the following formula (1) (Additional Form 25).

[0190] 4≦f×WD≦60 (1)

[0191] 17 , when the power receiving coil 40 is provided at position 40D on the inner surface of the tread portion D, the distance WD between the reinforcing layer 11 and the power receiving coil 40 is the distance in the tire radial direction between the radially inner surface of the belt layer 20a provided on the innermost side in the tire direction and the radially outer surface of the power receiving coil 40. When the power receiving coil 40 is provided at position 40E on the tire inner surface opposite the tire side surface, the distance WD is the shortest distance between the radially inner surface of the steel reinforcement 33 and the radially outer surface of the power receiving coil 40. Furthermore, when the power receiving coil 40 is provided at position 40G on the tire inner surface via a fixing member 42, the distance WD between the reinforcing layer 11 and the power receiving coil 40 is the shortest distance between the radially inner surface of the belt layer 20a provided on the innermost side in the tire direction and the radially outer surface of the power receiving coil 40, and includes the thickness of the fixing member 42.

[0192] The lower the frequency of the magnetic field, the longer the wavelength, making it difficult for the magnetic field to pass through gaps in metal, but the attenuation per distance is small. On the other hand, the higher the frequency of the magnetic field, the shorter the wavelength, making it easier for the magnetic field to pass through gaps in metal, but the attenuation per distance is large. Furthermore, the magnetic field attenuates more the farther it is from the reinforcing layer 11, but if it is too close to the reinforcing layer 11, it is difficult to efficiently link the magnetic field to the receiving coil 40.

[0193] The relationship between the spacing WG between the steel cords 13, the distance WD between the reinforcing layer 11 and the power receiving coil 40, the frequency f, and the power supply efficiency will be described below with reference to Figures 18 and 19. Figures 18 and 19 are schematic diagrams showing the relationship between the reinforcing layer 11, the power receiving coil 40, and the magnetic field. Note that although the power transmitting coil is not shown in Figures 18 and 19, it is located at a sufficient distance from the reinforcing layer 11. The power transmitting coil generates an AC magnetic field of a predetermined frequency f. The AC magnetic field passes through the spacing WG between the steel cords 13 in the reinforcing layer and interlinks with the power receiving coil 40. That is, current flows through the power receiving coil 40 by resonating at the same frequency as the frequency f.

[0194] 18 , if the distance WD between the power receiving coil 40 and the reinforcing layer 11 is too close relative to the spacing WG between the steel cords 13, the strength of the magnetic field received by the power receiving coil 40 will vary significantly depending on the position of the power receiving coil 40. Therefore, depending on the position at which the power receiving coil 40 is attached during manufacturing, the received power may be extremely small, which may result in large variations in power supply efficiency between products. Furthermore, because the power receiving coil 40 receives the magnetic field that passes through the spaces between the steel cords 13, if the power receiving coil 40 is too close to the reinforcing layer 11, more magnetic flux will pass through without linking with the power receiving coil 40, resulting in a relatively small amount of interlinking magnetic flux.

[0195] 19 , as the distance WD between the power receiving coil 40 and the reinforcing layer 11 increases relative to the spacing WG between the steel cords 13, the power receiving coil 40 receives a wider range of magnetic fields that pass through the spacing WG between the steel cords 13. If the distance WD between the reinforcing layer 11 and the power receiving coil 40 is appropriate, the power receiving coil 40 can interlink with a large amount of magnetic flux, which stabilizes the amount of received power depending on the position where the power receiving coil 40 is attached and can reduce variation in power supply efficiency between products. Note that if the distance WD between the power receiving coil 40 and the reinforcing layer 11 is too large, the magnetic field becomes weaker, resulting in reduced power supply efficiency.

[0196] When the distance WD (m) between the reinforcing layer 11 and the receiving coil 40 and the frequency f (kHz) of the magnetic field supplied from the transmitting coil satisfy the above formula (1), the receiving coil can be located in a position where the magnetic field can easily reach, thereby more reliably suppressing a decrease in power supply efficiency. In other words, when 4≦f×WD, variation in received power depending on the installation position of the receiving coil 40 can be suppressed. When f×WD≦60, the receiving coil 40 can interlink with more magnetic flux.

[0197] [Additional Form 26] In Basic Form 3 or a form in which Basic Form 3 is combined with any one of Additional Forms 19 to 25, the distance WD (m) between the reinforcing layer 11 and the receiving coil 40 is preferably 2.0 to 25 times the spacing WG between adjacent steel cords 13 contained in the reinforcing layer 11 (Additional Form 26), and more preferably 2.5 to 20 times.

[0198] When the power receiving coil 40 is provided on the inner surface of the tread portion, the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 is 2.0 to 25 times the spacing WG between adjacent steel cords 13 included in the belt 20. When the power receiving coil 40 is provided on the inner surface of the tire opposite the side surface of the tire, the distance WD (m) is 2.0 to 25 times the spacing between adjacent steel cords when the power receiving coil 40 is included in the reinforcing layer 11 of the sidewall portion B, i.e., the steel reinforcement 33. Setting the above value to 2.0 times or more can reduce variations in received power depending on the installation position of the power receiving coil 40. Setting the above value to 25 times or less ensures that the magnetic field has sufficient strength to more reliably link with the power receiving coil 40.

[0199] By keeping the value of "WD / WG" within the above range, where WD (m) is the distance between the reinforcing layer 11 and the receiving coil 40 and WG is the spacing between adjacent steel cords 13, the size of the fixing member 42 that fixes the receiving coil 40 to the inner surface of the tire is prevented from becoming excessive, and a decrease in power supply efficiency can be more reliably suppressed.

[0200] [Additional Form 27] ​​In Basic Form 3 or a form obtained by adding any one of Additional Forms 19 to 26 to Basic Form 3, the reinforcing layer 11 has a plurality of main portions 43 in which the spacing between adjacent steel cords 13 is W1, and void portions 45 arranged between the plurality of main portions 43, the spacing between adjacent main portions 43 in the void portions 45 is W2, and the spacing W2 is preferably 1.5 to 3.5 times the spacing W1 (Additional Form 27), and more preferably 1.8 to 3.0 times.

[0201] As shown in FIGS. 20A and 20B , the reinforcing layer 11 has a plurality of steel cords 13 arranged at regular intervals. The reinforcing layer 11 has a plurality of main portions 43. The plurality of main portions 43 are arranged with gaps 45 interposed therebetween. The distance between adjacent steel cords in the main portions 43 is W1. Each of the plurality of main portions 43 is formed of approximately the same number of steel cords 13. A gap 45 is arranged between the main portions 43. The gap 45 maintains the distance between adjacent main portions 43 at W2. When the distance W1 and the distance W2 satisfy the relationship "1.5≦(W2 / W1)≦3.5," a gap 45 where no steel cords 13 exist is formed at a predetermined interval. In other words, the reinforcing layer 11 has gaps 45, which allow a magnetic field to pass through more easily. Therefore, the tire 10B can suppress a decrease in power supply efficiency. When the interval W2 is 1.5 times or more the interval W1, the magnetic field easily passes through the reinforcing layer 11. When the interval W2 is 3.5 times or less the interval W1, the reinforcing layer 11 can sufficiently reinforce the tire structure.

[0202] [Additional Configuration 28] In Basic Configuration 3 or a configuration in which any one of Additional Configurations 19 to 27 is added to Basic Configuration 3, it is preferable that the reinforcing layer 11 is a belt 20 provided in the tread portion D, and that a power receiving coil 40 is provided on the tire inner surface radially inward of the belt 20, and that the power receiving coil 40 is a loop coil centered on the tire rotation axis (Additional Configuration 28).

[0203] As shown in FIG. 21 , the power receiving coil 40 is provided on the inner surface of the tire radially inward of the belt 20. FIG. 21 is a meridian cross section of a tire in which the power receiving coil 40 is disposed at a position 40D, which is approximately the center in the tire width direction, of the inner surface of the tire corresponding to the tread portion. The power receiving coil 40 is a loop coil, and as shown in FIG. 22 , a conductive wire is wound in a cylindrical shape around the tire rotation axis so as to be aligned circumferentially in the tire width direction along the inner surface of the tire corresponding to the tread portion. The number of turns of the power receiving coil 40 is preferably 1 to 5. The diameter of the conductive wire of the power receiving coil 40 is preferably 0.5 to 1.2 mm.

[0204] By providing the power receiving coil 40 on the tire inner surface corresponding to the tread portion D, the distance to the power transmitting coil provided on the tire radially outer side is shortened, thereby improving power supply efficiency. Therefore, in the tire 10B, when a power transmitting coil is provided on the tire radially outer side, a decrease in power supply efficiency can be suppressed.

[0205] The power receiving coil 40 may be provided in an area on the inner side in the tire width direction relative to the pair of outer circumferential main grooves 38, i.e., on the tire inner surface corresponding to the center land portion 35. By providing the power receiving coil 40 on the tire inner surface corresponding to the center land portion 35, heat generation on the tire inner surface is reduced, so heat from the power receiving coil 40 is easily dissipated and durability is excellent.

[0206] As shown in FIG. 23 , the power receiving coil 40 may be provided at a position 40M on the tire inner surface corresponding to the shoulder land portion 39. The power receiving coil 40 is a loop coil, and as shown in FIG. 24 , a conductive wire is wound cylindrically around the tire rotation axis so as to be aligned in the tire width direction along the tire inner surface corresponding to the shoulder land portion 39. The magnetic field generated by the power transmitting coil not only passes through the gap WG between the steel cords 13 of the belt 20, but also can reach the power receiving coil 40 by wrapping around the tire width direction end of the belt 20 from the outer side in the belt width direction. Because the shoulder land portion 39 is close to the sidewall portion B, which has little metal material, providing the power receiving coil 40 on the tire inner surface corresponding to the shoulder land portion 39 makes it less susceptible to the steel cords 13 of the belt 20 in power supply from the outer side in the tire width direction or the outer side in the tire radial direction. In other words, the steel cords 13 of the belt 20 are less likely to interfere with the magnetic field interlinking with the power receiving coil 40, thereby suppressing a decrease in power supply efficiency in the tire 10B.

[0207] [Additional Configuration 29] In Basic Configuration 3 or a configuration in which any one of Additional Configurations 19 to 28 is added to Basic Configuration 3, the reinforcing layer 11 is provided in a region in the tire radial direction from the end of the belt 20 in the tire width direction to the outermost position in the tire radial direction of the bead core 14, and when the tire radial length from the bead toe 32 to the tread surface 34 is SH in a meridian cross section of the tire in an unloaded state, the power receiving coil 40 is provided at a position 40E on the tire inner surface in a region within 50% of the tire radial length SH from the bead toe 32, and the power receiving coil 40 is preferably a loop coil centered on the tire rotation axis (Additional Configuration 29).

[0208] The tire radial length SH is the tire radial length from the bead toe 32 to the tread surface 34 when the tire is mounted on a rim, normal internal pressure is applied, and no load is applied. As shown in FIG. 25 , the power receiving coil is disposed at a position within 50% of the tire radial length SH from the bead toe 32. At least a portion of the power receiving coil 40 overlaps with the steel reinforcement 33 in the tire radial direction. The power receiving coil 40 is a loop coil, and as shown in FIG. 26 , a conductive wire is wound around the tire rotation axis so as to be aligned in the tire radial direction along the tire inner surface corresponding to the sidewall portion B. The power receiving coil 40 may be wound in a spiral shape. The number of turns of the power receiving coil 40 is preferably 1 to 5. The diameter of the conductive wire of the power receiving coil 40 is preferably 0.5 to 1.2 mm.

[0209] By providing the power receiving coil 40 within the above range on the tire inner surface corresponding to the sidewall portion B, the distance to the power transmitting coil provided on the outer side in the tire width direction is shortened, thereby improving power supply efficiency. Therefore, when the power transmitting coil is provided on the outer side in the tire width direction, the tire 10B can suppress a decrease in power supply efficiency. Furthermore, by providing the power receiving coil 40 on the tire inner surface in a region within 50% of the tire radial length SH from the bead toe 32, the effect of deformation of the tire 10B on the power receiving coil 40 is suppressed, and the power receiving coil 40 is less likely to fall off the tire inner surface, improving durability.

[0210] [Additional Configuration 30] In the basic configuration 3 or the configuration in which any one of the additional configurations 19 to 29 is added to the basic configuration 3, it is preferable that the basic configuration 3 is in a state where it is assembled to a regular rim (additional configuration 30).

[0211] The tire 10B is mounted on a rim 6 for use. In this case, the power receiving coil 40 may be provided on the rim 6 as shown in FIG. 12 . For example, the power receiving coil 40 may be provided at position 40H on the rim inner surface facing the tire cavity surface as shown in FIG. 12 . The power receiving coil 40 may be wound in a cylindrical shape with the conductors aligned in the tire width direction. In another example, the power receiving coil 40 may be provided at position 40I on the rim outer surface opposite the rim inner surface facing the tire cavity surface. In yet another example, as shown in FIG. 14 , the power receiving coil 40 may be provided at position 40J on the rim inner surface facing the tire cavity surface, and may be wound in a spiral shape with the conductors aligned in the tire radial direction.

[0212] <Other Aspects of the Tire and Wireless Power Supply System> The carbon content of the inner liner 12, which are components of the tire 10B, is preferably 45 to 75 parts by mass (mass parts when the rubber is 100; the same applies below), the carbon content of the side tread is preferably 25 to 65 parts by mass, the carbon content of the bead filler 16 is preferably 40 to 80 parts by mass, and the carbon content of the covering rubber of the carcass 18 is preferably 35 to 70 parts by mass. By adopting these respective content amounts, it is possible to achieve the desired thermal conductivity in each rubber layer while also achieving the tire performance described above. While the thermal conductivity of rubber is typically determined by the type of polymer and compounding ingredients, adjusting the carbon content is most preferable because it makes it easy to change the electrical properties (because carbon particles themselves are highly conductive) and easily achieve the rubber properties required for the tire.

[0213] 1. First Example Below, a comparison of the effects of the present application between the first invention defined in the claims of the present application (hereinafter referred to as "Invention Examples 1-1 to 1-5") corresponding to the first embodiment will be described.

[0214] The tire size was set to 245 / 40R19 (specified by JATMA), and the tire shown in Figure 1 was manufactured. The various conditions for tires 10 of invention examples 1-1 to 1-5 are as shown in Table 1 below.

[0215]

[0216] In Table 1, "Tire radial position of the receiving coil relative to the outermost position OP," "Tire radial position of the receiving coil relative to a position 15% of the length SH from the bead toe," "Coating layer," "MR-ER (%)," and "Tw / Aw" conform to the definitions described in this specification.

[0217] The tires of Invention Examples 1-1 to 1-5 thus fabricated were mounted on a test vehicle (a passenger car with an engine displacement of 3000 cc) equipped with a power transmitting coil, and the vehicle was driven at a speed of 60 km / h on a wet road test course where water was sprayed to a depth of 2 mm. The ratio (power transmission efficiency) of power 2 received by the power receiving coil (and capacitor resonant circuit) to power 1 transmitted from the power transmitting coil was measured, and these ratios were expressed as indexes with Invention Example 1 set to 100. The ratios of power 1 and 2 were measured using a wattmeter. The results are also shown in Table 1.

[0218] According to Table 1, it can be seen that all of the wireless power supply systems within the technical scope of the present invention exhibit excellent power transmission efficiency, and in turn achieve excellent power supply efficiency.

[0219] 2. Second Example Below, we will describe a comparison of the effects of the present application between the second inventions (hereinafter referred to as "Invention Examples 2-1 to 2-5") defined in the claims of the present application corresponding to the second embodiment. Note that, as mentioned above, the difference in the effects of the present application between Invention Examples 2-1 to 2-5 and the conventional example (the example described in Patent Document 1) is clear from the configuration, so we will not particularly compare them.

[0220] Using a tire size of 245 / 40R19 (specified by JATMA), wireless power transfer systems 50 (invention examples 2-1 to 2-5 and the reference example) shown in Fig. 4 were fabricated, and the efficiency of power transfer from the power transmitting coil 52 to the power receiving coil 40 was investigated. The various conditions of the tires included in each of the wireless power transfer systems 50 of invention examples 2-1 to 2-5 and the reference example are as shown in Table 2 below.

[0221]

[0222] In Table 2, CH, P, Kv, SH, r, DH, WH, Gi, Hi, Rc, Rs, etc. conform to the definitions described in this specification.

[0223] For the wireless power transfer systems of Examples 2-1 to 2-5 thus fabricated, the ratio (power transmission efficiency) of power 2 received by the receiving coil (and capacitor resonant circuit) to power 1 transmitted from the transmitting coil 52 was measured and expressed as an index where Example 1 was set to 100. The measurement of the ratio of power 1 to 2 was performed using a vector network analyzer. The results are also shown in Table 2. In this specification, a ratio of transmitted power (power transmission efficiency) of 95 or more is considered to be good.

[0224] According to Table 2, it can be seen that all of the wireless power supply systems within the technical scope of the present invention exhibit excellent power transmission efficiency, and in turn achieve excellent power supply efficiency.

[0225] 3. Third Example Below, a comparison of the effects of the present application between the third inventions (hereinafter referred to as "Invention Examples 3-1 to 3-9") defined in the claims of the present application corresponding to the third embodiment will be described.

[0226] The tire size was set to 245 / 40R19 (specified by JATMA), and the tires shown in Fig. 12 were manufactured. The conditions for the tires of Examples 3-1 to 3-10 are as shown in Table 3 below.

[0227]

[0228] In Table 3, "area ratio (SR / S)," "spacing between steel cords (mm)," "cross-sectional circumference (mm)," "number of filaments," "winding width / spacing," "f×D," "D / spacing," and "W2 / W1" conform to the definitions described in this specification.

[0229] For the wireless power transfer systems using the tires of Invention Examples 3-1 to 3-10 fabricated in this manner, the ratio (power transfer efficiency) of power 2 received by the power receiving coil (and capacitor resonant circuit) to power 1 transmitted from the power transmitting coil was measured, and these ratios were expressed as indexes with Invention Example 3-1 set to 100. The ratios of power 1 and 2 were measured using a vector network analyzer. The results are also shown in Table 3.

[0230] According to Table 3, it can be seen that all of the wireless power supply systems within the technical scope of the present invention exhibit excellent power transmission efficiency, and in turn achieve excellent power supply efficiency.

[0231] DESCRIPTION OF REFERENCE NUMERALS 6 Rim 8 Rim flange 10, 10A, 10B Tire 11 Reinforcing layer 12 Inner liner 13 Steel cord 14 Bead core 15 Rubber portion 16 Bead filler 18 Carcass 20 Belt 22, 22A Belt cover 24 Rim cushion 26 Side tread 28 Wing tip 29 Second carcass 30 Cap tread 31 Lug groove 32 Bead toe 33 Steel reinforcement 34 Tread surface 35 Center land portion 36 Circumferential main groove 37 Circumferential narrow groove 38 Outer circumferential main groove 39 Shoulder land portion 40 Power receiving coil 40A to 40M Position 42 Fixing member 43 Main portion 44 Power line 45 Gap portion 46 Electronic device 50 Wireless power supply system 52 Power transmitting coil 54 Wheelhouse 56 Power transmission coil unit 57 Inner end 58 Case 60 Power transmission side surface A Bead portion AR Power receiving vicinity area B Sidewall portion C Shoulder portion CP Tire equatorial plane CW Tire radial area D Tread portion L1 First imaginary line L2 Second imaginary line L3 Third imaginary line O Tire center OP Outermost position P1 Intersection point P2 Intersection point R Tire circumferential range WH Tire radial area α Angle β Angle

Claims

1. A tire having a tread portion with a tread surface, a pair of bead portions, and a pair of sidewall portions provided between the tread portion and the bead portions, the tire comprising a power receiving coil that receives power supplied by an alternating magnetic field from outside the tire, wherein the power receiving coil is provided radially inward of the outermost position where a first imaginary line having an angle of 15° with the tire equatorial plane in a tire meridian cross-sectional view of the tire in an unloaded state contacts the tire side surface.

2. The tire according to claim 1, wherein the power receiving coil is provided radially outward of a position that is 15% of the tire radial length SH from the bead toe to the tread surface in a tire meridian cross-sectional view of the tire in an unloaded state.

3. The tire according to claim 1, wherein the power receiving coil is provided on the inner surface of the tire opposite to the outer surface of the tire having the tread surface.

4. The tire according to claim 1, wherein in a power receiving vicinity region between an intersection of a second imaginary line inclined 30° radially inward from the inner end of the power receiving coil in the tire radial direction toward the outer side in the tire width direction and the tire outer surface and an intersection of a third imaginary line inclined 30° radially outward from the outer end of the power receiving coil in the tire radial direction toward the outer side in the tire width direction and the tire outer surface, the height of the unevenness of the tire outer surface is 1 mm or less in 50% or more of the area of the power receiving vicinity region.

5. The tire according to claim 4, wherein a coating layer made of a component other than rubber is provided on the tire outer surface in the power receiving vicinity region.

6. The tire according to claim 1, wherein the groove area ratio in the tread portion is 12% or more and 38% or less, and the groove area ratio in the region from the tire equatorial plane to the inner side of vehicle mounting is larger than the groove area ratio in the region from the tire equatorial plane to the outer side of vehicle mounting, and the difference is 3.5 percentage points or more.

7. The tire according to claim 1, wherein the length Aw between the pair of outermost positions and the contact width Tw in a state where a load of 80% of the normal load is applied satisfy the following formula (1): Tw ≦ 0.88 × Aw... (1) 8. The tire according to any one of claims 1 to 6 in a state of being assembled to a normal rim.

9. A wireless power supply system that supplies AC power to a power transmission coil forming a resonance circuit with a capacitor and a coil, and transmits power to the power reception coil forming a resonance circuit with the capacitor and the coil, the wireless power supply system including the tire according to claim 1 or 2.

10. The wireless power supply system according to claim 9, wherein the power reception coil is disposed inside the vehicle mounting.

11. The wireless power supply system according to claim 10, wherein at least a part of the power reception coil is located within a power supply region that extends in the winding axis direction of the power transmission coil across both longitudinal ends of the power transmission coil in a tire meridian cross-sectional view.

12. The wireless power supply system according to claim 10, wherein the power transmission coil is installed in a range of 60° on both sides in the tire circumferential direction centered on an imaginary line extending vertically upward from the tire center.

13. The wireless power supply system according to claim 10, wherein the power transmission side surface of the power transmission coil unit including the power transmission coil that faces the power reception coil has a contact angle of 50° or more.

14. The wireless power supply system according to claim 10, wherein the angle formed by the power transmission side surface of the power transmission coil unit including the power transmission coil and the tire radial direction as viewed from the tire meridian cross-section is in a range of 70° toward the side close to the tire and 30° toward the side away from the tire with the inner end in the tire radial direction of the power transmission coil unit as the center.

15. A tire having a bead core, a bead filler provided outside the bead core in the tire radial direction, a carcass folded around the bead core, and a belt provided outside the carcass in the tire radial direction, the tire comprising a power reception coil on the inner cavity surface for receiving power supplied by an alternating magnetic field from outside the tire, wherein in a tire meridian cross-sectional view, a deflection index Kv / P (= Gr (mm)) obtained by dividing the vertical spring constant Kv (N / mm) of the tire by the air pressure P (kPa) inside the tire and the tire radial dimension CH (mm) from the innermost position in the tire radial direction of the tire to the outermost position in the tire radial direction of the power reception coil satisfy 7 ≦ CH / Gr ≦ 95.

16. A tire comprising a tread portion having a tread surface, a pair of bead portions, a pair of sidewall portions provided between the tread portion and the bead portions, a reinforcing layer having a steel cord, and a power receiving coil that receives power supplied by an alternating magnetic field from outside the tire, wherein the area ratio of the portion excluding the steel cord to the area of the reinforcing layer in a front view is 0.1 or more and 0.7 or less.

Images