Tire and wireless power supply system

Abstract

The purpose of the present invention is to provide a tire capable of achieving excellent power supply efficiency without hindering a magnetic field reaching a power reception coil from a power transmission coil by a metal member even if a steel cord is used for a belt. In a tire meridian cross-sectional view, a power reception coil (40) is provided in a tire radial direction region (WH) from the outermost position of a bead core (14) in the tire radial direction to the innermost position of the belt (20) in the tire radial direction, and the relative dielectric constant of a member excluding a tread part and disposed in the tire radial direction region is 3.5-250.

Description

Tires and wireless power supply systems

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

[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] 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.

[0005] When a tire rolls, iron particles are generated from the brake rotor and brake pads due to braking. In a wireless power receiving system, these iron particles can block part of the magnetic field that would otherwise reach the power receiving coil from the power transmitting coil.

[0006] In the wireless power receiving system of Patent Document 1, the power receiving coil is usually attached to a metal rim, so the rim affects the AC magnetic field, which tends to 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.

[0007] A first object of the present invention is to provide a tire and a wireless power transfer system using the tire that can achieve excellent power transfer efficiency without the magnetic field reaching the power receiving coil from the power transmitting coil being blocked by a metal member between the two coils, even when a steel cord is used for the belt.

[0008] A second object of the present invention is to provide a tire and a wireless power supply system using the tire that can suppress the influence of iron powder generated from a brake rotor or brake pads on a power receiving system.

[0009] A third object of the present invention is to provide a tire and a wireless power transfer system using the tire that can achieve excellent power transfer efficiency due to the selection of an installation location for a power receiving coil and the manner in which heat is dissipated at the installation location.

[0010] According to the present invention, the following Aspects 1 to 17 are provided as means for achieving the first object (first invention), the following Aspects 18 to 27 are provided as means for achieving the second object (second invention), and the following Aspects 28 to 36 are provided as means for achieving the third object (third invention). [Aspect 1] A tire having bead cores, bead fillers provided on the tire radially outer side of the bead cores, a carcass folded back around the bead cores, 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, the power receiving coil is provided in a tire radial direction region from the tire radially outermost position of the bead cores to the tire radially innermost position of the belt, and wherein the relative permittivity of members arranged in the tire radial direction region, excluding a tread portion, is 3.5 or more and 250 or less. [Aspect 2] The tire according to Aspect 1, wherein the inner liner has a relative dielectric constant in the range of 8 to 90, and the carcass has a relative dielectric constant in the range of 4 to 20. [Aspect 3] The tire according to Aspect 1 or 2, wherein the rubber material constituting the side tread has a relative dielectric constant in the range of 3.5 to 40, and the rubber material constituting the rim cushion and the bead filler has a relative dielectric constant in the range of 70 to 235. Aspect 4 The tire according to any one of Aspects 1 to 3, wherein the power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil, and wherein, in a tire meridian cross section, a power receiving coil radial region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction, and power receiving vicinity regions adjacent to both sides in the tire radial direction of the power receiving coil radial region and whose tire radial length is defined by 15% of the tire radial length of the tire radial region, have side treads with a relative dielectric constant in the range of 3.5 to 37 and no rim cushions or bead fillers arranged therein, and the relative dielectric constants of the rim cushions and bead fillers arranged radially inward of the power receiving coil radial region and the power receiving vicinity regions are in the range of 70 to 250.Aspect 5: The tire according to any one of Aspects 1 to 4, wherein the power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil, wherein a side tread having a relative dielectric constant of not less than 3.5 and not more than 37 is arranged in a power receiving coil radial direction region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction in a tire meridian cross section view, and wherein at least one of a bead filler and a rim cushion having a relative dielectric constant of not less than 70 and not more than 235 is arranged in at least a part of a power receiving vicinity region that is adjacent to both sides in the tire radial direction of the power receiving coil radial direction and whose length in the tire radial direction is defined by 15% of the length in the tire radial direction of the tire radial direction region. Aspect 6: The tire according to any one of Aspects 1 to 5, wherein the power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil, and wherein a side tread having a relative dielectric constant of 3.5 or more and 37 or less is disposed in a power receiving coil radial direction region whose tire radial length is defined by the length between both end portions of the power receiving coil in the tire radial direction in a tire meridian cross section view, and at least one of a bead filler and a rim cushion having a relative dielectric constant of 70 or more and 220 or less is disposed in the power receiving coil radial direction region. [Aspect 7] The tire according to any one of Aspects 1 to 6, wherein the power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil, and wherein at least one of a bead filler and a rim cushion having a relative dielectric constant in the range of 70 to 200 is disposed in a power receiving coil radial direction region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction in a tire meridian cross section view, and wherein no side tread is disposed, and wherein the relative dielectric constant of the side tread disposed outside the power receiving coil radial direction region in the tire radial direction is in the range of 3.5 to 40. [Aspect 8] The tire according to any one of Aspects 1 to 7, wherein the difference in relative dielectric constant between each member disposed in the tire radial direction and another member adjacent in the tire width direction is 170 or less.[Aspect 9] The tire according to any one of Aspects 1 to 8, wherein the power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil, and wherein a difference in relative permittivity between a component disposed in a power receiving coil radial direction region, the component being defined in a tire radial direction length by the length between both ends of the power receiving coil in the tire radial direction in a tire meridian cross section view, and another component adjacent thereto in the tire width direction has a difference in relative permittivity of 165 or less. [Aspect 10] The tire according to any one of Aspects 1 to 9, wherein a conductive wire of the power receiving coil is installed on a surface of an inner liner constituting a tire cavity surface via a support layer, and wherein the support layer present between the conductive wire and the inner liner in the tire radial direction region has a lower relative permittivity than the inner liner. Aspect 11: The tire according to any one of Aspects 1 to 10, wherein the power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil, and a relationship between the sum of the products of the relative permittivity and the thickness in the tire width direction of each member on an imaginary line in the tire width direction at an arbitrary position within a power receiving coil radial direction region whose tire radial length is defined by the length between both ends of the power receiving coil in the tire radial direction in a tire meridian cross section view, and a shortest distance Dmin from the conductive wire of the power receiving coil to an inner liner satisfies the range of Equation (1). [Aspect 12] The tire according to any one of Aspects 1 to 11, further comprising a side support layer on an inner circumferential side of the carcass, the side support layer having a relative permittivity in the range of 8 to 90 and lower than the relative permittivity of the rim cushion or the bead filler, whichever has a higher relative permittivity. [Aspect 13] The tire according to Aspect 12, wherein, in a tire meridian cross section, in a power receiving coil radial direction region whose tire radial length is defined by the length between both tire radial direction ends of the power receiving coil, the maximum value of the tire width direction thickness of the side support layer is in the range of 4 mm to 12 mm. [Aspect 14] A wireless power supply system that provides 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 forms a resonant circuit with a capacitor and a coil, the wireless power supply system including the tire according to any one of Aspects 1 to 13. [Aspect 15] The wireless power feed system according to Aspect 14, wherein at least a portion of the power receiving coil is located within a power feeding region extending in a winding axis direction of the power transmitting coil across both longitudinal end portions of the power transmitting coil in a tire meridian cross section. [Aspect 16] The wireless power feed system according to Aspect 14 or 15, wherein the power transmitting coil is installed within a range of 60° on both sides in the tire circumferential direction about an imaginary line extending vertically upward from the center of the tire. [Aspect 17] The wireless power feed system according to any one of Aspects 14 to 16, wherein the power transmitting coil is installed in an unsprung member of a vehicle. [Aspect 18] A tire having bead cores, bead fillers provided on the tire radially outer side of the bead cores, a carcass folded back around the bead cores, 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, the power receiving coil is provided in a tire radially outer region from the tire radially outermost position of the bead cores to the tire radially innermost position of the belt, and the tire has an outer layer rubber exposed on a tire side surface of the tire radially inner region, the outer layer rubber containing 0.5 to 8.0 parts by mass of antioxidant per 100 parts by mass of rubber and 0.1 to 5.0 parts by mass of wax per 100 parts by mass of rubber.[Aspect 19] The tire according to Aspect 18, wherein the thickness of the outer layer rubber is 2.5 to 20.0 mm. [Aspect 20] The tire according to Aspect 18 or 19, wherein, in a tire mounted on a standard rim and pressurized to a normal internal pressure, the length SH in the tire radial direction from the bead toe to the tread surface of the tire in an unloaded state and the amount of deflection D in the tire width direction before and after application of a load corresponding to 80% of the normal load to the tire satisfy the following formula (2): 0.0278×SH-1.33≦D≦0.286×SH-13.7 (2) [Aspect 21] The cross-sectional area S of the outer layer rubber. ｏ and 100% modulus M ｏ and the cross-sectional area S of the inner layer rubber that is disposed on the inner side of the outer layer rubber in the tire width direction and is not exposed to the tire side surface. ｉ and 100% modulus M ｉ A tire according to any one of aspects 18 to 20, wherein the sum of the products of and satisfies the following formula (3): [Aspect 22] The tire according to any one of Aspects 18 to 21, wherein the height of the irregularities on the surface of the outer rubber layer is 2.0 mm or less. [Aspect 23] The tire according to any one of Aspects 18 to 22, wherein, in a tire meridian cross section, in a power receiving coil radial direction region whose tire radial length is defined by the length between both ends of the power receiving coil in the tire radial direction, and in power receiving vicinity regions adjacent to both sides of the power receiving coil radial direction in the tire and whose tire radial length is defined by 15% of the tire radial length of the tire radial direction region, the outer rubber layer contains 0.5 to 7.5 parts by mass of an antioxidant per 100 parts by mass of rubber and 0.1 to 4.5 parts by mass of wax per 100 parts by mass of rubber, and the height of the irregularities on the surface of the outer rubber layer is 1.5 mm or less. [Aspect 24] A wireless power feed system that provides 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 any one of Aspects 18 to 23. [Aspect 25] The wireless power feed system according to Aspect 24, in which 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 26] The wireless power feed system according to Aspect 24, in which the power transmitting coil is installed within a range of 60° on both sides in the tire circumferential direction, centered on an imaginary line that extends vertically upward from the center of the tire. [Aspect 27] The wireless power feed system according to Aspect 24, in which the power transmitting coil is installed in an unsprung member of a vehicle. [Aspect 28] 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, the thermal conductivity λ1 of the inner liner is 0.10 W / m·k or more in a tire radial region between both legs of perpendicular lines drawn from each of both tire radial end portions of the power receiving coil to an inner liner formed on the inner circumferential side of the carcass.[Aspect 29] The tire according to Aspect 28, wherein the power receiving coil is provided in a region in the tire radial direction from the outermost position of the bead core in the tire radial direction to the innermost position of the belt in the tire radial direction in a tire meridian cross section. [Aspect 30] In a tire meridian cross section taken at a point other than the end of the power receiving coil, the total wire cross-sectional area S (m ２ ) and the relationship between the resistance value r (Ω) of the power receiving coil at the frequency of the AC power and the thermal conductivity λ1 (W / m·k) of the inner liner is 1×10 ５ ≦r / (λ1×S)≦8×10 ７The tire according to Aspect 28 or 29, wherein the thermal conductivity λ2 of the rubber layers other than the inner liner is 0.13 W / m·k or greater in a tire radial direction region from the outermost position of the bead core in the tire radial direction to the innermost position of the belt in the tire radial direction. [Aspect 32] The tire according to any one of Aspects 28 to 31, further comprising a fixing member for fixing the power receiving coil to a tire cavity surface, wherein the relationship between a ratio [(Σθ2) / θ1] of a sum Σθ2 of tire circumferential installation angles θ2 of the fixing member to a tire circumferential arrangement angle θ1 of the power receiving coil 40 relative to the tire center, based on the tire center, and the thermal conductivity λ3 (W / m·k) of the fixing member satisfies the following: 0.14×[(Σθ2) / θ1]+0.13≦λ3≦0.38×[(Σθ2) / θ1]+0.42 [Aspect 33] The tire according to any one of Aspects 28 to 32, wherein the wire constituting the power receiving coil includes an electric wire and a coating layer coating the electric wire, wherein the thermal conductivity λ4 (W / m·k) of the coating layer is greater than the thermal conductivity λ1 (W / m·k) of the inner liner, and wherein the thickness of the coating layer is 10 to 100 μm. [Aspect 34] A wireless power transfer 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 transfer system including the tire according to any one of Aspects 28 to 33. [Aspect 35] The wireless power receiving coil according to Aspect 34, wherein at least a portion of the power receiving coil is located within a power transfer region that extends in a winding axis direction of the power transmitting coil across both longitudinal end portions of the power transmitting coil in a tire meridian cross section. [Aspect 36] The wireless power supply system according to Aspect 34 or 35, wherein the power transmission coil is installed within a range of 60° on both sides in the tire circumferential direction, centered on an imaginary line extending vertically upward from the center of the tire.

[0011] In the tire according to the first aspect of the present invention, improvements are made to the position of the power receiving coil on the tire cavity surface and the relative dielectric constant of the member. As a result, the tire according to the present invention can improve power supply efficiency. In the tire according to the second aspect of the present invention, improvements are made to the position of the power receiving coil on the tire cavity surface. Furthermore, the tire according to the present invention limits the contents of antioxidants and waxes contained in the outer layer rubber exposed on the tire sidewall. As a result, the tire according to the present invention can improve power supply efficiency. Furthermore, the tire according to the present invention can suppress a decrease in power supply efficiency due to aging while maintaining weather resistance. In the tire according to the third aspect of the present invention, improvements are made to the installation location of the power receiving coil on the tire cavity surface and the mode of heat dissipation at the installation location. As a result, the tire according to the present invention can improve power supply efficiency.

[0012] FIG. 1 is a tire meridian cross-section showing one side in the tire width direction of a tire according to a first embodiment, with the tire equatorial plane (not shown) as the reference. FIG. 2 is a diagram showing a case where the tire 10 of FIG. 1 further includes a run-flat liner 32. FIG. 3 is a diagram showing a case where the tire 10 of FIG. 1 further includes a second filler 25. FIG. 4 is a diagram showing a case where the tire 10 of FIG. 1 further includes a steel reinforcement (SRF) 19. FIG. 5 is a tire meridian cross-section showing a main portion of the tire 10 according to additional embodiment 4. FIG. 6 is a schematic diagram for explaining a power receiving coil radial direction region R1, showing the tire 10 as viewed from the tire width direction. FIG. 7 is a tire meridian cross-section showing a main portion of the tire 10 according to additional embodiment 5. FIG. 8 is a tire meridian cross-section showing a main portion of the tire 10 according to additional embodiment 6. FIG. 9 is a tire meridian cross-section showing a main portion of the tire 10 according to additional embodiment 6, showing a case where the tire 10 includes a second filler 25. Fig. 10 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Embodiment 7. Fig. 11 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Embodiment 10, and is an enlarged view showing a power receiving coil 40 and its periphery that is installed on the surface of an inner liner 12 of the tire cavity via a support layer 44. Fig. 12 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Embodiment 11, and is an enlarged view showing a power receiving coil 40 and its periphery that is installed on the surface of the inner liner 12 of the tire cavity via a support layer 44. Fig. 13 is a view showing a power transmitting coil 52 and 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) provided with a power receiving coil 40 for a wireless power feed system 50 according to this embodiment. 14A shows an example in which the outer portion of the power transmitting coil 52 in the tire radial direction overlaps with the inner portion of the power receiving coil 40 in the tire radial direction, and FIG. 14B shows an example in which the inner portion of the power transmitting coil 52 in the tire radial direction overlaps with the outer portion of the power receiving coil 40 in the tire radial direction. FIG. 15 is a diagram showing the installation position of the power transmitting coil 52 in the wireless power feeding system 50 according to this embodiment.FIG. 16 is a schematic diagram illustrating the position at which the power transmitting coil 52 is installed in the tire 10 shown in FIG. 1 . FIG. 17 is a schematic diagram illustrating the position at which the power transmitting coil 52 is installed in the tire 10 shown in FIG. 1 . FIG. 18 is a diagram illustrating an arrangement of the power receiving coil 40 (an arrangement in which the power receiving coils 40 are not continuous in the tire circumferential direction, unlike the arrangement in FIG. 2 ). FIGS. 18(a) to 18(f) are examples illustrating a power receiving coil 40 consisting of two, three, four, five, six, and eight sets of power receiving coil elements 40a, respectively. FIG. 18(g) is an example in which multiple power receiving coil elements 40a are stacked in the tire radial direction. FIG. 18(h) is an example in which some of the multiple power receiving coil elements 40a extend at an angle with respect to the tire radial direction. FIG. 19 is a tire meridian cross section (half in the tire width direction) illustrating a power supply arrangement in which power is supplied from the power receiving coil 40 via a power line 45 to an electronic device 47 attached to the tire cavity surface in the tire 10 shown in FIG. 1 . FIG. 20 is a meridian cross-sectional view of a tire according to a second embodiment, showing one side in the tire width direction, based on the tire equatorial plane (not shown). FIG. 21 is a meridian cross-sectional view of a modified example of the tire according to the second embodiment. FIG. 22 is a meridian cross-sectional view provided for explaining the amount of deflection in the tire width direction of the tire according to the second embodiment. FIG. 23 is a meridian cross-sectional view of a tire according to a third embodiment, showing one side in the tire width direction, based on the tire equatorial plane (not shown). FIG. 24 is a schematic diagram showing the arrangement of the power receiving coil 40 shown in FIG. 23 in the tire circumferential direction. FIG. 25 is a schematic diagram showing a specific example of [(Σθ2) / θ1], which is the installation ratio of the fixing members 41 to the power receiving coil 40 shown in FIG. 23 . FIG. 25A shows an example in which multiple fixing members 41a are installed at regular intervals, and FIG. 25B shows an example in which one fixing member 41b is installed. FIG. 26 is a cross-sectional view of the wire 42 constituting the power receiving coil 40.

[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 the present invention (Basic Mode 1 and Additional Modes 2 to 13 shown below) and a first embodiment of a wireless power supply system according to the present invention (Basic Mode 14 and Additional Modes 15 to 17 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 of what is obvious to a person skilled in the art. [Basic Mode 1] FIG. 1 is a meridian cross-section of a tire according to a first embodiment, showing one side in the tire width direction with the tire equatorial plane (not shown) as the reference. Note that this figure shows the tire portion opposite the contact patch when the tire is mounted on a rim, normal internal pressure is applied, and a normal load is applied (the same applies hereinafter to tire inventions).

[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-up portion 18b wound 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) 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.

[0018] A rim cushion 24 is provided further outward in the tire width direction from the folded-up portion 18b of the carcass 18, which is provided outward in the tire width direction from the bead core 14 and the bead filler 16. A side tread 26, a wing tip 28, and a cap tread 30 are provided in this order radially outward of the rim cushion 24.

[0019] Figure 2 shows the case where the tire 10 of Figure 1 further includes a run-flat liner 32. The run-flat liner 32 is formed on the outer side of the inner liner 12 in the tire width direction over at least the sidewall portion B (and possibly also including the bead portion A and shoulder portion C). The tire according to this embodiment is not limited to the example shown in Figure 1, and also includes a run-flat tire as shown in Figure 2, in which the run-flat liner 32 is provided on the outer side of the inner liner 12 in the tire width direction, mainly in the sidewall portion B.

[0020] FIG. 3 shows a case where the tire 10 of FIG. 1 further includes a second filler 25. The second filler 25 is made of a rubber different from that of the rim cushion 24, and is provided adjacent to the folded-up portion 18b of the carcass 18 on the outer side in the tire width direction of the folded-up portion 18b. FIG. 4 shows a case where the tire 10 of FIG. 1 further includes a steel reinforcement (SRF) 19. The steel reinforcement 19 is provided adjacent to the folded-up portion 18b of the carcass 18 on the inner side in the tire width direction of the folded-up portion 18b. The provision of the second filler 25 or the steel reinforcement 19 can improve the rigidity of the sidewall portion B. The tire according to this embodiment is not limited to the example shown in FIG. 1 , and also includes tires provided with the second filler 25 or the steel reinforcement 19 as shown in FIGS. 3 and 4 .

[0021] 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 laminated in the tire radial direction at the tire equatorial plane. 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.

[0022] 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 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.

[0023] 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), 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 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.

[0024] The belt 20 is a reinforcing layer provided on the tire radially outer side of the carcass 18, and is a member that tightens the carcass 18 to increase the rigidity of the tread portion D, improves steering stability, and reduces rolling resistance by reducing strain deformation. The belt 20 can be composed of multiple belt layers (two belt layers 20a, 20b in the example shown in FIG. 1) stacked 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.

[0025] 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 (three belt cover layers 22a, 22b, and 22c in the example shown in FIG. 1) 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.

[0026] The rim cushion 24 is provided in an area that comes into contact with 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 area. The rim cushion 24, second filler 25, side tread 26, wing tips 28, cap tread 30, and run-flat liner 32 can all be made of conventional rubber materials depending on the required characteristics of each.

[0027] Assuming the presence of the components 12 to 30 of the tire 10 shown in FIG. 1 (possibly including at least one of the run-flat liner 32 in FIG. 2 , the second filler 25 in FIG. 3 , and the steel reinforcement 19 in FIG. 4 ), the tire 10 according to this embodiment includes a power receiving coil 40 ( FIG. 1 ) on the tire cavity surface, located on the inner side in the tire width direction, for receiving AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10. Here, power transmission may be achieved, for example, by a magnetic resonance method. 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 ). 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.

[0028] Power supply using the tire 10 according to this embodiment involves, for example, first converting DC current obtained from an on-board battery (not shown) into AC current using an AC power supply device, and then applying this AC current to a power transmission coil (attached, for example, to a knuckle or hub carrier that is a part of the steering axle of the vehicle, or to the tire-side surface of any part that makes up the strut structure), thereby 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.

[0029] To achieve this power supply, in the tire 10 according to this embodiment, the power receiving coil 40 is provided in a tire radial direction region from the outermost position in the tire radial direction of the bead core 14 (point P1 shown in FIGS. 1 to 3) to the innermost position in the tire radial direction of the belt 20 (point P2 shown in FIGS. 1 to 3) as seen in a tire meridian cross section ( FIG. 1 ). As shown in FIG. 1 , the tire radial direction region is a region that has a tire radial length of WH as seen in a tire meridian cross section and extends in the tire width direction. Hereinafter, for ease of explanation, the tire radial direction region will be represented by the symbol WH.

[0030] More specifically, the tire radial region WH is a region in the tire radial direction defined by the radially outer end (point P1) of the bead core 14, which may include a ferromagnetic material, and the innermost position in the tire radial direction of the belt 20, which may include a ferromagnetic material (point P2, the outer end of the belt 20 in the tire width direction). The region is outer in the tire radial direction than point P1 and inner in the tire radial direction than point P2. Note that in the tire radial region WH, the tire 10 is curved in a convex shape that is outwardly convex. Therefore, if the power receiving coil 40 is provided in the tire radial region WH, the power receiving coil 40 will basically be positioned outer in the tire width direction than points P1 and P2. However, this is not always the case depending on the positions of points P1 and P2 in the tire width direction. That is, if point P1 is clearly more inward in the tire width direction than point P2 and the power receiving coil 40 is positioned near the bead core 14, the power receiving coil 40 may be positioned inner in the tire width direction than the width direction end (point P2) of the belt 20. Furthermore, if point P1 is clearly located further outward in the tire width direction than point P2 and the receiving coil 40 is positioned near the belt 20, it may be located further inward in the tire width direction than the radially outer end (point P1) of the bead core 14.

[0031] 1 to 3 show a case where no ferromagnetic reinforcing material is provided around the bead core 14. On the other hand, Fig. 4 shows a case where steel reinforcement (SRF) 19 is provided as a ferromagnetic reinforcing material around the bead core 14 (outside the bead core 14 in the tire radial direction). In the case of the tire 10 shown in Fig. 4, the innermost position in the tire radial direction of the tire radial region WH is point P3 shown in Fig. 4.

[0032] Furthermore, in the tire 10 according to this embodiment, the relative permittivity (which refers to the ratio between the permittivity of a specific member and the permittivity of a vacuum; the same applies hereinafter) of the members, excluding the tread portion D, arranged in the tire radial direction region WH 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 is 3.5 or more and 250 or less. Note that "members excluding the tread portion D" refers to the remaining members excluding the cap tread 30, wing tips 28, belt cover 22, belt edge cushion, etc.

[0033] (Operation, etc.) As described above, a wireless power receiving system is known in the art that supplies power between a power transmitting coil buried near the road surface and a power receiving coil attached to the centerline of a wheel in the tire width direction (see Patent Document 1, Figure 1). In this wireless power receiving system, the magnetic field that reaches the power receiving coil from the power transmitting coil may be affected by the belt. For example, if a metal belt cord is used for the belt in this wireless power receiving system, part of the magnetic field that would otherwise reach the power receiving coil from the power transmitting coil may be blocked by the magnetic material (belt cord) included in the belt, which may prevent excellent power supply efficiency from being achieved.

[0034] Therefore, the inventors have conducted extensive research into a tire 10 that can achieve excellent power supply efficiency, even when a metal belt cord is used for the belt 20 shown in FIG. 1 , without blocking part of the magnetic field that would otherwise reach the power receiving coil 40 from the power transmitting coil by components of the tire 10 that contain magnetic material present between the two coils.

[0035] Specifically, the inventors have thoroughly studied the optimum position for forming the receiving coil 40, which is provided on the inner side of the tire 10 in the tire width direction, relative to the transmitting coil (not shown) provided outside the tire 10.

[0036] Furthermore, the inventors have thoroughly studied the range of the relative dielectric constant, excluding the members of the tread portion D, which are arranged in the tire radial direction region WH 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.

[0037] First, the inventor focused on the multiple line segments in Figure 1 that reach each point (starting point) on the tire cavity surface 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 discovered that by positioning the receiving coil 40 so that it does not deviate from the tire cavity surface included in this region, most of the magnetic field generated between the two coils will not be blocked by the belt 20, which may contain magnetic material.

[0038] 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 inventor further studied how to also define the radially inner end of this installation area. As a result, the inventor 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 line segments, and locating 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.

[0039] The inventors have found that providing the power receiving coil 40 as described above makes it possible to accommodate power supply modes from both the outer side in the tire width direction (the direction of arrow a1 in FIG. 1 ) and the outer side in the tire radial direction (the direction of arrow a2 in FIG. 1 ) when power is supplied from outside the tire 10 by electromagnetic induction, and that high transmission efficiency can be achieved by minimizing the influence of ferromagnetic materials in the belt 20, bead portion A, etc. Note that the term "ferromagnetic material" as used herein primarily refers to iron (steel). For example, the ferromagnetic material in the bead portion A is the steel cord of the bead core 14 (including the steel reinforcement 19 in the configuration example of FIG. 4 ), and the ferromagnetic material of the belt 20 is a magnetic material such as the steel cord that constitutes the belt 20.

[0040] Furthermore, the inventors have focused on the relative permittivity of members arranged near the power receiving coil 40 and have found that the relative permittivity of members, excluding the tread portion D, arranged in the tire radial direction region WH 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 affects the transmission efficiency of wireless power transmission from the power transmitting coil to the power receiving coil 40. Note that the members here include members such as the inner liner 12, the bead filler 16, the carcass 18, the rim cushion 24, the second filler 25, the side tread 26, the wing tip 28, and the run-flat liner 32.

[0041] More specifically, the inventors have found that if the relative permittivity of these components is too high, electromagnetic waves will be attenuated significantly during power transmission, resulting in reduced transmission efficiency. On the other hand, the inventors have found that if the relative permittivity of these components is too low, for example as a result of reducing the carbon content, it becomes difficult to compound these components to maintain their original rubber properties, making it difficult to achieve the desired tire performance. The relative permittivity of the carcass 18 is a value including fiber cords and other reinforcing materials.

[0042] Based on the above findings, in the tire 10 according to this embodiment, the power receiving coil 40 is provided in a region WH in the tire radial direction that extends from the outermost position in the tire radial direction of the bead core 14 to the innermost position in the tire radial direction of the belt 20. As a result, in the tire 10 according to this embodiment, an excessive number of tire 10 components that may contain magnetic material are not provided between the power transmitting coil and the power receiving coil 40, thereby improving power supply efficiency.

[0043] Furthermore, based on the above findings, in the tire 10 according to this embodiment, the relative dielectric constant of the members arranged in the tire radial direction region WH 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, excluding the tread portion D, is 3.5 or more and 250 or less. Here, the relative dielectric constant is more preferably 4.0 or more and 240 or less, and extremely preferably 4.5 or more and 230 or less. The relative dielectric constant is determined by the polymer structure and compounding agents of the members, etc. The relative dielectric constant is a measurement value at 10 MHz. Furthermore, the dielectric loss tangent (tan δ) of these members is preferably 0.02 to 1.6.

[0044] The dielectric constant and the dielectric loss tangent (tan δ) are values ​​measured at 23° C. and 10 MHz. More specifically, the dielectric constant and the dielectric loss tangent (tan δ) are measured values ​​at a frequency of 10 MHz when a sheet sample of a certain thickness is prepared using a member cut out from the tire 10, and an AC voltage is applied to the sheet sample at 23° C. using an HP 4291B RF impedance / material analyzer manufactured by Hewlett Packard as the impedance analyzer and a 16453A dielectric material test fixture manufactured by Hewlett Packard as the test fixture.

[0045] (Additional Form 2) In Basic Form 1, when the magnetic field passes through the tire radial region WH, it passes through the inner liner 12 and the carcass 18, and therefore the relative permittivity of the inner liner 12 and the carcass 18 has a large effect on the magnetic field of wireless power supply and a large effect on transmission efficiency. Furthermore, although the inner liner 12 and the carcass 18 have a relatively smaller thickness in the tire width direction than the other components, they are expected to be positioned closer to the power receiving coil 40 than the other components, and therefore have a larger effect on the magnetic field of wireless power supply than the other components.

[0046] If the relative dielectric constants of the inner liner 12 and the carcass 18 are too high, the attenuation of electromagnetic waves during power transmission increases, resulting in a decrease in transmission efficiency.On the other hand, if the relative dielectric constants of the inner liner 12 and the carcass 18 are too low, it becomes difficult to compound these components to maintain their original rubber physical properties, making it difficult to achieve the desired tire performance.

[0047] Therefore, in Basic Form 1, it is preferable that the relative dielectric constant of the inner liner 12 is in the range of 8 to 90, and the relative dielectric constant of the carcass 18 is in the range of 4 to 20 (Additional Form 2).

[0048] Since the inner liner 12 includes an air barrier layer and an adhesive rubber layer, the relative dielectric constant of the inner liner 12 is a value for the entire member including the air barrier layer and the adhesive rubber layer. The relative dielectric constant of the inner liner 12 is more preferably 8.5 or more and 85 or less, and extremely preferably 9 or more and 80 or less.

[0049] Furthermore, since the carcass 18 contains reinforcing fibers, the relative dielectric constant of the carcass 18 is a value for the entire member, including fiber cords and the like used as reinforcing materials. The relative dielectric constant of the carcass 18 is more preferably 4.5 or more and 18 or less, and extremely preferably 5 or more and 16 or less. The dielectric loss tangent (tan δ) of the inner liner 12 is preferably 0.06 to 0.80, and even more preferably 0.08 to 0.74. The dielectric loss tangent (tan δ) of the carcass 18 is preferably 0.06 to 0.16, and even more preferably 0.07 to 0.15.

[0050] (Additional Form 3) In Basic Form 1 or a form in which Additional Form 2 is added to Basic Form 1, it is preferable that the relative dielectric constant of the side tread 26 (the rubber material of the side tread 26) is in the range of 3.5 or more and 40 or less, and the relative dielectric constant of the rim cushion 24 and the bead filler 16 (the rubber material of the rim cushion 24 and the bead filler 16) is in the range of 70 or more and 235 or less (Additional Form 3).

[0051] The rim cushion 24 and the bead filler 16 are both located near the bead portion A, and the required properties of the rubber material therefor are generally the same, but different from those required for the rubber material of the side tread 26. The side tread 26 is expected to be located closer to the power receiving coil 40 than the rim cushion 24 and the bead filler 16, and is expected to have a greater impact on the magnetic field of the wireless power supply than the rim cushion 24 and the bead filler 16. Additional form 3 maintains high transmission efficiency while maintaining the physical properties required for the side tread 26 (elongation, low heat generation, etc.) and the physical properties required for the rim cushion 24 and the bead filler 16 (hardness, elastic modulus, etc.). The relative dielectric constant of the side tread 26 is more preferably 4.0 or greater and 38 or less, and extremely preferably 4.5 or greater and 36 or less. The relative dielectric constant of the rim cushion 24 and the bead filler 16 is more preferably 75 or greater and 230 or less, and extremely preferably 80 or greater and 225 or less. Preferably, the dielectric loss tangent (tan δ) of the side tread 26 is 0.02 to 0.5, and more preferably 0.03 to 0.45. Preferably, the dielectric loss tangent (tan δ) of the rim cushion 24 and the bead filler 16 is 0.6 to 1.5.

[0052] In the case of a tire 10 including a second filler 25 as shown in Fig. 3, the relative dielectric constant of the second filler 25 is preferably equal to that of the bead filler 16. That is, the relative dielectric constant of the second filler 25 is preferably in the range of 70 to 235, more preferably 75 to 230, and most preferably 80 to 225. In addition, the dielectric loss tangent (tan δ) of the second filler 25 is preferably 0.6 to 1.5.

[0053] (Additional Embodiment 4) FIG. 5 is a meridian cross-sectional view of a tire showing a main portion of a tire 10 according to Additional Embodiment 4. As shown in FIG. In basic form 1 or a form in which at least one of additional forms 2 and 3 is added to basic form 1, as shown in the figure, the power receiving coil 40 generates power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil 40, and in a tire meridian cross section view, a power receiving coil radial region R1 whose tire radial length is defined by the length between both tire radial ends of the power receiving coil 40, and a power receiving vicinity region R2 adjacent to both sides of the power receiving coil radial region R1 in the tire radial direction and whose tire radial length is defined as 15% of the tire radial length of the tire radial region WH, side treads 26 whose relative dielectric constant is in the range of 3.5 to 37 are arranged, and a rim cushion 24 and bead fillers 16 are not arranged, and it is preferable that the relative dielectric constants of the rim cushion 24 and bead fillers 16 arranged radially inward of the power receiving coil radial region R1 and the power receiving vicinity region R2 are in the range of 70 to 250 (additional form 4).

[0054] As shown in FIG. 5 , in a tire 10 according to additional embodiment 4, the entire power receiving coil radial region R1 and the power receiving vicinity region R2 overlap with the side tread 26 in the tire radial direction, but do not overlap with the rim cushion 24 and the bead filler 16 in the tire radial direction. As shown in FIG. 5 , the power receiving coil radial region is a region that has a tire radial length R1 and extends in the tire width direction in a tire meridian cross section. The power receiving vicinity region is a region that has a tire radial length R2 and extends in the tire width direction in a tire meridian cross section. For ease of explanation, the power receiving coil radial region will be represented by the symbol R1, and the power receiving vicinity region will be represented by the symbol R2. In additional embodiment 4, in the positional relationship shown in FIG. 5 , the side tread 26 has a relative dielectric constant in the range of 3.5 to 37, and the rim cushion 24 and the bead filler 16 have a relative dielectric constant in the range of 70 to 250.

[0055] According to Additional Form 4, by arranging the power receiving coil 40 so as to avoid the tire radial positions of the rim cushion 24 and bead filler 16, which have relatively high relative dielectric constants, high transmission efficiency can be achieved and the effect of the physical properties of the rim cushion 24 and bead filler 16 on transmission efficiency can be reduced, allowing the physical properties of the rim cushion 24 and bead filler 16 to be set within a range suitable for tire performance. Therefore, the relative dielectric constants of the rim cushion 24 and bead filler 16 are allowed to be higher than those of Additional Form 3, but the relative dielectric constant of the side tread 26 is kept lower than that of Additional Form 3 because it has a significant effect on transmission efficiency. The relative dielectric constant of the side tread 26 is more preferably 4.0 to 35, and extremely preferably 4.5 to 33. The relative dielectric constants of the rim cushion 24 and bead filler 16 are more preferably 75 to 240, and extremely preferably 80 to 230. Preferably, the dielectric loss tangent (tan δ) of the side tread 26 is 0.02 to 0.47, and the dielectric loss tangent (tan δ) of the rim cushion 24 and the bead filler 16 is 0.6 to 1.6.

[0056] In the case of a tire 10 including a second filler 25 as shown in Fig. 3, the relative dielectric constant of the second filler 25 is preferably equal to that of the bead filler 16. That is, the relative dielectric constant of the second filler 25 is preferably in the range of 70 to 250, more preferably 75 to 240, and most preferably 80 to 230. In addition, the dielectric loss tangent (tan δ) of the second filler 25 is preferably 0.6 to 1.6.

[0057] 6A and 6B are schematic diagrams illustrating a power receiving coil radial region R1, showing the tire 10 as viewed from the tire width direction. FIG. 6A shows an example in which multiple power receiving coil elements 40a, each with a diameter that fits within the tire radial region WH, are arranged in the tire circumferential direction, and the power receiving coil 40 is composed of multiple power receiving coil elements 40a. FIG. 6B shows an example in which one power receiving coil 40 is configured using the entire circumference of the tire. The tire radial length (= R1) of the power receiving coil radial region R1 is the maximum length occupied by the power receiving coil 40 in the tire radial direction. In both the examples of FIG. 6A and FIG. 6B, the power receiving coil radial region R1 is included in the tire radial region WH.

[0058] (Additional Embodiment 5) FIG. 7 is a tire meridian cross-sectional view showing a main portion of a tire 10 according to Additional Embodiment 5. In basic form 1 or a form in which at least one of additional forms 2 and 3 is added to basic form 1, as shown in the figure, the receiving coil 40 generates power by receiving a magnetic field transmitted from a power transmission coil arranged outside the tire in the tire width direction of the receiving coil 40, and in a tire meridian cross section view, a receiving coil radial region R1 whose tire radial length is defined by the length between both tire radial ends of the receiving coil 40 is provided with a side tread 26 whose relative dielectric constant is in the range of 3.5 to 37 and no rim cushion 24 or bead filler 16 is arranged, and it is preferable that at least one of the bead filler 16 and the rim cushion 24 whose relative dielectric constant is in the range of 70 to 235 is arranged in at least a part of a receiving vicinity region R2 adjacent to the receiving coil radial region R1 on both sides in the tire radial direction and whose tire radial length is defined as 15% of the tire radial length of the tire radial region WH (additional form 5).

[0059] As shown in Figure 7, in a tire 10 according to additional aspect 5, the entire power receiving coil radial direction region R1 overlaps with the side tread 26 in the tire radial direction, and at least a portion of the power receiving vicinity region R2 overlaps with at least one of the rim cushion 24 and the bead filler 16 (the rim cushion 24 in Figure 7) in the tire radial direction. At least a portion of the power receiving vicinity region R2 may be configured to overlap with both the rim cushion 24 and the bead filler 16 in the tire radial direction. In additional aspect 5, in the positional relationship shown in Figure 7, the relative dielectric constant of the side tread 26 is in the range of 3.5 or more and 37 or less, and the relative dielectric constants of the rim cushion 24 and the bead filler 16 are in the range of 70 or more and 235 or less.

[0060] The tire cavity surface on which the power receiving coil 40 is provided repeatedly deforms and releases during tire rotation. To enhance the durability of the power receiving coil 40 against these deformations, it may be preferable to position the power receiving coil 40 close to the rim cushion 24 or bead filler 16 on the tire's radially inner side. According to Additional Form 5, when the power receiving coil 40 must be placed close to the rim cushion 24 and bead filler 16 for reasons such as durability, the relative permittivity of at least the rim cushion 24 and bead filler 16 located in the power receiving vicinity region R2 is set within the above-mentioned range. This allows for excellent transmission efficiency by not locating the rim cushion 24 and bead filler 16 in the power receiving coil radial direction region R1, and for the physical properties of the rim cushion 24 and bead filler 16 to be within a range suitable for tire performance, thereby achieving excellent durability. The relative permittivity of the side tread 26 is more preferably 4.0 or more and 35 or less, and most preferably 4.5 or more and 33 or less. The relative dielectric constant of the rim cushion 24 and bead filler 16 is more preferably 75 or greater and 230 or less, and most preferably 80 or greater and 225 or less. Preferably, the dielectric tangent (tan δ) of the side tread 26 is 0.02 to 0.47, and the dielectric tangent (tan δ) of the rim cushion 24 and bead filler 16 is 0.6 to 1.5.

[0061] In the case of a tire 10 including a second filler 25 as shown in Fig. 3, the relative dielectric constant of the second filler 25 is preferably equal to that of the bead filler 16. That is, the relative dielectric constant of the second filler 25 is preferably in the range of 70 to 235, more preferably 75 to 230, and most preferably 80 to 225. In addition, the dielectric loss tangent (tan δ) of the second filler 25 is preferably 0.6 to 1.5.

[0062] 8 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Mode 6. In Basic Mode 1 or a mode in which at least one of Additional Modes 2 and 3 is added to Basic Mode 1, as shown in the drawing, the power receiving coil 40 generates electric power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil 40, and it is preferable that, in the tire meridian cross-section view, a side tread 26 having a relative dielectric constant in the range of 3.5 to 37 is arranged in a power receiving coil radial direction region R1 whose length in the tire radial direction is defined by the length between both ends of the power receiving coil 40 in the tire radial direction, and at least one of a bead filler 16 and a rim cushion 24 having a relative dielectric constant in the range of 70 to 220 is arranged (Additional Mode 6).

[0063] As shown in Figure 8, in a tire 10 according to additional aspect 6, the power receiving coil radial region R1 is configured to overlap the side tread 26 in the tire radial direction, and at the same time overlap with at least one of the rim cushion 24 and the bead filler 16 (the rim cushion 24 in Figure 8). The power receiving coil radial region R1 may also be configured to overlap with both the rim cushion 24 and the bead filler 16 in the tire radial direction. In additional aspect 6, in the positional relationship shown in Figure 8, the relative dielectric constant of the side tread 26 is in the range of 3.5 or more and 37 or less, and the relative dielectric constants of the rim cushion 24 and the bead filler 16 are in the range of 70 or more and 220 or less.

[0064] According to Additional Form 6, when at least one of a rim cushion 24 and a bead filler 16, which have a relatively high relative dielectric constant, and a side tread 26, which has a relatively low relative dielectric constant, are disposed in the power receiving coil radial direction region R1, the relative dielectric constant of at least one of the rim cushion 24 and the bead filler 16 predominantly affects transmission efficiency. Therefore, by setting the relative dielectric constants of the rim cushion 24 and the bead filler 16 within the above range, the transmission efficiency required for wireless power transfer can be maintained. The relative dielectric constant of the side tread 26 is more preferably 4.0 or greater but 35 or less, and extremely preferably 4.5 or greater but 33 or less. The relative dielectric constants of the rim cushion 24 and the bead filler 16 are more preferably 75 or greater but 215 or less, and extremely preferably 80 or greater but 210 or less. Preferably, the dielectric loss tangent (tan δ) of the side tread 26 is 0.02 to 0.47, and the dielectric loss tangent (tan δ) of the rim cushion 24 and the bead filler 16 is 0.6 to 1.4.

[0065] 9 is a tire meridian cross section showing a main portion of a tire 10 according to Additional Embodiment 6, and is a diagram showing a case where the tire 10 includes a second filler 25. In this case, the relative dielectric constant of the second filler 25 is preferably equivalent to that of the bead filler 16. That is, the relative dielectric constant of the second filler 25 is preferably in the range of 70 to 220, more preferably 75 to 215, and extremely preferably 80 to 210. In addition, the dielectric loss tangent (tan δ) of the second filler 25 is preferably 0.6 to 1.4.

[0066] 10 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Mode 7. In Basic Mode 1 or a mode in which at least one of Additional Modes 2 and 3 is added to Basic Mode 1, as shown in the drawing, the power receiving coil 40 generates electric power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil 40, and in the tire meridian cross-section view, at least one of a bead filler 16 and a rim cushion 24 having a relative dielectric constant in the range of 70 to 200 is arranged in a power receiving coil radial direction region R1 whose length in the tire radial direction is defined by the length between both ends of the power receiving coil 40 in the tire radial direction, and no side tread 26 is arranged, and it is preferable that the relative dielectric constant of the side tread 26 arranged outside the power receiving coil radial direction region R1 in the tire radial direction is in the range of 3.5 to 40 (Additional Mode 7).

[0067] As shown in Figure 10 , in a tire 10 according to Additional Configuration 7, the power receiving coil radial region R1 is configured to overlap in the tire radial direction with at least one of the bead filler 16 and the rim cushion 24 (both the bead filler 16 and the rim cushion 24 in the example shown in Figure 10 ), while not overlapping with the side tread 26. The power receiving coil radial region R1 may also be configured to overlap in the tire radial direction with either the rim cushion 24 or the bead filler 16. In Additional Configuration 7, in the positional relationship shown in Figure 10 , the relative dielectric constants of the rim cushion 24 and the bead filler 16 are in the range of 70 or more and 200 or less, and the relative dielectric constant of the side tread 26 is in the range of 3.5 or more and 40 or less.

[0068] According to Additional Form 7, when at least one of the rim cushion 24 and the bead filler 16, which have a relatively high relative dielectric constant, is disposed in the power receiving coil radial direction region R1, and the side tread 26 is not disposed, the transmission efficiency required for wireless power transfer can be maintained by setting the relative dielectric constants of the rim cushion 24 and the bead filler 16 within the above range. The relative dielectric constants of the rim cushion 24 and the bead filler 16 are more preferably 75 to 195, and extremely preferably 80 to 190. The relative dielectric constant of the side tread 26 is more preferably 4.0 to 38, and extremely preferably 4.5 to 36. Preferably, the dielectric loss tangent (tan δ) of the rim cushion 24 and the bead filler 16 is 0.6 to 1.3, and the dielectric loss tangent (tan δ) of the side tread 26 is 0.02 to 0.50.

[0069] In the case of a tire 10 including a second filler 25 as shown in Fig. 3, the relative dielectric constant of the second filler 25 is preferably equal to that of the bead filler 16. That is, the relative dielectric constant of the second filler 25 is preferably in the range of 70 to 200, more preferably 75 to 195, and most preferably 80 to 190. In addition, the dielectric loss tangent (tan δ) of the second filler 25 is preferably 0.6 to 1.3.

[0070] (Additional Form 8) In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 7, it is preferable that each member arranged in the tire radial region WH has a difference in relative dielectric constant from other members adjacent to it in the tire width direction of 170 or less (Additional Form 8).

[0071] For example, along dash-dotted line II' shown in FIG. 1, the inner liner 12, the carcass 18, the side tread 26, and the wing tip 28 are adjacently arranged in this order from the inner side in the tire width direction. Also, along dash-dotted line II-II' shown in FIG. 1, the inner liner 12, the carcass 18, and the side tread 26 are adjacently arranged in this order from the inner side in the tire width direction. Also, along dash-dotted line III-III' shown in FIG. 1, the inner liner 12, the carcass 18, the rim cushion 24, and the side tread 26 are adjacently arranged in this order from the inner side in the tire width direction. Also, along dash-dotted line IV-IV' shown in FIG. 3, the inner liner 12, the main body 18a of the carcass 18, the bead filler 16, the folded-up portion 18b of the carcass 18, the second filler 25, the rim cushion 24, and the side tread 26 are adjacently arranged in this order from the inner side in the tire width direction. The difference in relative permittivity between these adjacent members is 170 or less. More specifically, considering all combinations, including the configuration with the run-flat liner 32 shown in Figure 2, the difference in dielectric constant between adjacent components can be expressed by the following inequality: The dielectric constant of the inner liner 12 is IL, the dielectric constant of the carcass 18 is C, the dielectric constant of the side tread 26 is ST, the dielectric constant of the wing tip 28 is WT, the dielectric constant of the second filler 25 is 2FL, the dielectric constant of the bead filler 16 is BFL, the dielectric constant of the rim cushion 24 is RC, and the dielectric constant of the run-flat liner 32 is RFL. The dielectric constant of the inner liner 12 is a value for the entire component, including the air barrier layer and adhesive rubber layer. The dielectric constant of the carcass 18 is a value for the entire component, including the reinforcing fibers. The dielectric constants of the other components are the dielectric constants of the rubber layers of the components. |IL-C|≦170 |ST-C|≦170 |ST-WT|≦170 |RC-C|≦170 |RC-ST|≦170 |C-BFL|≦170 |C-2FL|≦170 |ST-2FL|≦170 |RC-2FL|≦170 |IL-RFL|≦170 |C-RFL|≦170

[0072] When the difference in relative permittivity between adjacent members is large at their boundary surfaces, high-frequency magnetic fields are reflected, reducing transmission efficiency. However, according to Additional Form 8, the difference in relative permittivity between adjacent members is 170 or less, thereby suppressing the reflection of high-frequency magnetic fields and reducing transmission efficiency. More specifically, even when the difference in relative permittivity between adjacent members is 170 or less, high-frequency electromagnetic waves are reflected at their boundary surfaces. However, in this case, the loss due to eddy currents generated in the metal of the bead portion A of the tire 10 or the belt 20 is greater, so the reflection of high-frequency electromagnetic waves is relatively insignificant. Therefore, by setting the difference in relative permittivity between adjacent members to 170 or less, the eddy current loss in the bead portion A or the belt 20 can be limited to that in the tire. Furthermore, by having all members in the tire radial region WH satisfy the above range, the degree of freedom in the placement of the power receiving coil 40 is increased. It is more preferable that the difference in relative permittivity between adjacent members be 160 or less, and extremely preferably 150 or less. Preferably, the difference in dielectric loss tangent (tan δ) of the relative dielectric constant between adjacent members is 0.9 or less.

[0073] (Additional Form 9) In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 8, the receiving coil 40 generates electric power by receiving a magnetic field transmitted from a power transmission coil arranged outside the tire in the tire width direction of the receiving coil 40, and it is preferable that, in a tire meridian cross section, the difference in relative permittivity between components arranged in a receiving coil radial region R1, whose tire radial length is defined by the length between both tire radial ends of the receiving coil, is 165 or less (Additional Form 9).

[0074] Because the components arranged in the power receiving coil radial region R1 have a particularly large impact on power transmission efficiency, it is preferable to make the difference in relative permittivity between adjacent components smaller than that between components arranged outside the power receiving coil radial region R1 in the tire radial direction, and therefore it is preferable to satisfy the above range. The difference in relative permittivity between adjacent components is more preferably 155 or less, and extremely preferably 150 or less. In addition, the difference in dielectric loss tangent (tan δ) of the relative permittivity of adjacent rubber layers is preferably 0.88 or less.

[0075] (Additional Form 10) In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 9, the conductive wire 43 of the receiving coil 40 is installed on the surface of the inner liner 12 that forms the tire cavity surface via a support layer 44, and it is preferable that the relative dielectric constant of the support layer 44 present between the conductive wire 43 and the inner liner 12 in the tire radial region WH is lower than the relative dielectric constant of the inner liner 12 (Additional Form 10).

[0076] 11 is a tire meridian cross-section showing a main portion of a tire 10 according to additional embodiment 10, and is an enlarged view of a power receiving coil 40 and its surroundings that are installed on the surface of an inner liner 12 that constitutes the tire cavity surface via a support layer 44. Fig. 11(A) shows an example in which the conductive wire 43 of the power receiving coil 40 is installed on the surface of the inner liner 12 via an insulating support layer 44, and the conductive wire 43 is exposed to the tire cavity. Fig. 11(B) shows an example in which the conductive wire 43 of the power receiving coil 40 is installed on the surface of the inner liner 12 via a support layer 44, and the conductive wire 43 is covered with the support layer 44. Fig. 11(C) shows an example in which the conductive wire 43 of the power receiving coil 40 is installed on the surface of the inner liner 12 via a support layer 44, and the conductive wire 43 is covered with a layer 46 separate from the support layer 44.

[0077] 11(A) to 11(C), a support layer 44 is interposed between the conductive wire 43 and the inner liner 12, and the conductive wire 43 and the inner liner 12 are not in contact. Current flows through the conductive wire 43 due to magnetic field resonance, generating a magnetic field around the conductive wire 43. The magnetic flux density increases the closer to the conductive wire 43, and the dielectric constant of materials close to the conductive wire 43 has a significant effect on magnetic field attenuation. According to additional form 10, by separating the conductive wire 43 from the inner liner 12 and placing a support layer 44 with a low dielectric constant between the inner liner 12 and the conductive wire 43, magnetic field attenuation can be suppressed. The support layer 44 and the other layer 46 are made of an insulating material, which may be, for example, rubber, resin, or the like.

[0078] (Additional Embodiment 11) Fig. 12 is a tire meridian cross-section showing a main portion of a tire 10 according to Additional Embodiment 11, and is an enlarged view of a power receiving coil 40 and its surroundings that is installed on the surface of an inner liner 12 in the tire cavity via a support layer 44. Fig. 12(A) shows an example, similar to Fig. 11(A), in which the conductive wire 43 of the power receiving coil 40 is installed on the surface of the inner liner 12 via an insulating support layer 44, and the conductive wire 43 is exposed to the tire cavity. Fig. 12(B) shows an example in which the support layer 44 is embedded in the inner liner 12. Dmin in formula (1) is the shortest distance from the conductive wire 43 of the power receiving coil 40 to the inner liner 12, as shown in Figs. 12(A) and 12(B).

[0079] In the basic configuration 1 or a configuration in which at least one of additional configurations 2 to 10 is added to the basic configuration 1, the power receiving coil 40 generates electric power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil 40, and the relative dielectric constant εr of each member on a virtual line in the tire width direction at an arbitrary position within the power receiving coil radial direction region R1 in a tire meridian cross section is ｋ and thickness G in the tire width direction ｋ It is preferable that the relationship between the sum of the products of (mm) (k = 1 to n (n is the number of components on the imaginary line)) and the shortest distance Dmin from the conductive wire 43 of the power receiving coil 40 to the inner liner 12 be within the range of formula (1) (Additional form 11). The relative permittivity of the inner liner 12 is a value for the entire component, including the air barrier layer and adhesive rubber layer. The relative permittivity of the carcass 18 is a value for the entire component, including fiber cords and the like used as reinforcing materials. The thicknesses of the inner liner 12 and carcass 18 are the thicknesses of the components themselves.

[0080]

[0081] The inventor first calculated the relative dielectric constant εr of each member on the above virtual line. ｋ and thickness G in the tire width direction ｋThe inventors have found that the greater the sum of the products of (mm), the greater the magnetic field attenuation. As described above, current flows through the conductive wire 43 due to magnetic field resonance, but the closer to the conductive wire 43, the greater the magnetic flux density, and the greater the influence of the relative permittivity of the support layer 44 close to the conductive wire 43 on the attenuation of the magnetic field. For this reason, the inventors have found that if the thickness (shortest distance Dmin) of the support layer 44 is small, the relative permittivity εr of each member ｋ and thickness G in the tire width direction ｋ Based on the finding that magnetic field attenuation is suppressed even if the sum of the products (mm) is relatively large, the relationship of formula (1) was found.

[0082] According to Additional Form 11, attenuation of the magnetic field passing through the tire 10 can be suppressed, and loss of the magnetic field formed around the conductive wire 43 can also be suppressed, thereby maintaining high transmission efficiency. If the value of Σ / Dmin in Equation (1) is smaller than 200, the shortest distance Dmin becomes excessively large, and the support layer 44 becomes thick, which increases the tire mass or the thickness G of each member. ｋ If the value of Σ / Dmin is too small, the tire 10 cannot have an adequate rigidity. If the value of Σ / Dmin is greater than 6000, the shortest distance Dmin is too small, the inner liner 12 and the conductive wire 43 become close to each other, and the attenuation of the magnetic field increases, or the thickness G of each member becomes too large. ｋ If the relative permittivity εr of each member is too large, the magnetic field will be attenuated significantly. Therefore, it is preferable that the range of the formula (1) is satisfied. ｋ and thickness G in the tire width direction ｋ The value obtained by dividing the sum of the products (mm) by the shortest distance Dmin is preferably 250 or more and 5,500 or less, and extremely preferably 300 or more and 5,000 or less.

[0083] (Additional Form 12) In Basic Form 1 or a form in which at least one of Additional Forms 2 to 11 is added to Basic Form 1, as shown in Figure 2, a side support layer (run-flat liner 32) is provided on the inner side of the carcass 18 in the tire width direction, and it is preferable that the relative dielectric constant of the side support layer (rubber material) is in the range of 8 to 90 and is lower than the relative dielectric constant of either the rim cushion 24 or the bead filler 16 (rubber material), whichever has the higher relative dielectric constant (Additional Form 12).

[0084] Additional embodiment 12 corresponds to the configuration shown in FIG. 2 . Because the run-flat liner 32 is disposed across the tire radial region WH, the power receiving coil 40 is disposed close to the run-flat liner 32. The greater the thickness t of the run-flat liner 32, the greater the effect on magnetic field attenuation. According to additional embodiment 12, the rubber layers disposed around the power receiving coil 40 are the inner liner 12, carcass 18, and run-flat liner 32. The power receiving coil 40 is spaced apart from the rim cushion 24 and bead filler 16. Therefore, if the relative permittivity of the run-flat liner 32 is lower than that of the rim cushion 24 or bead filler 16, whichever has the higher relative permittivity, the run-flat liner 32 thickens the sidewall portion B, thereby mitigating the degree of magnetic field attenuation caused by this. The relative permittivity of the rubber material constituting the run-flat liner 32 is more preferably in the range of 8.5 to 85, and most preferably 9 to 80 or less. Preferably, the difference in dielectric loss tangent (tan δ) of the run-flat liner 32 is 0.06 or more and 0.8 or less.

[0085] (Additional Embodiment 13) In Additional Embodiment 12, for example, in the tire meridian cross section shown in FIG. 2 , in the power receiving coil radial region R1, whose tire radial length is defined by the length between both tire radial ends of the power receiving coil 40, the maximum tire width direction thickness t of the side support layer (run-flat liner 32) is preferably in the range of 4 to 12 mm (Additional Embodiment 13). If the thickness t of the run-flat liner 32 is greater than 12 mm, the run-flat liner 32 will generate more heat during travel, hindering heat dissipation from the power receiving coil 40. If the thickness t of the run-flat liner 32 is greater than 12 mm, the impact on magnetic field attenuation will be greater. Furthermore, by setting the thickness t of the run-flat liner 32 to 4 mm or greater, the power receiving coil 40 can be spaced apart from the rim cushion 24 and bead filler 16, which have a higher dielectric constant, thereby minimizing the impact on transmission efficiency and achieving run-flat performance. Therefore, the maximum tire width direction thickness t of the run-flat liner 32 is preferably in the range of 4 to 12 mm. The maximum thickness t of the run-flat liner 32 in the tire width direction is more preferably in the range of 4.5 to 11.5, and most preferably 5 to 11. Also, the dielectric loss tangent (tan δ) of the run-flat liner 32 is preferably 0.06 to 0.8.

[0086] <Wireless Power Supply System> [Basic Form 14] Fig. 13 is a diagram showing a tire 10 (one side in the tire width direction based on the tire equatorial plane CP in a tire meridian cross section) provided with a power transmitting coil 52 and a power receiving coil 40 in a wireless power supply system 50 according to this embodiment. The figure shows the tire portion on the side opposite the contact patch 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 invention of the wireless power supply system). The power transmitting coil 52 shown in the figure is a coil with its winding axis 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 tire width direction in addition to the tire radial direction.

[0087] The power transmission coil 52 shown in the figure forms a resonant circuit with a capacitor and a coil, and is attached, for example, to the tire-side surface of a knuckle, which is a part of a steering axle of a vehicle (not shown).

[0088] In contrast, the power receiving coil 40 shown in Fig. 13 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. 13 is a tire of the basic configuration 1 related to the tire 10 described above, and a tire in which at least one of additional configurations 2 to 13 is added to the basic configuration 1, and its actions, functions, etc. are as described above.

[0089] 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. 13 , 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.

[0090] 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.

[0091] 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. Furthermore, the transmission gap G refers to the shortest distance between the power transmitting coil 52 and the power receiving coil 40 in FIG. 13 , that is, 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 in FIG. 13 .

[0092] Setting the transmission gap G to 10 mm or more can prevent excessive fluctuations in received power due to fluctuations in the relative positions of the power transmitting coil 52 and the power receiving coil 40 (shown in FIG. 13 ) 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 (toward the upper side in FIG. 13 ), 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.

[0093] In contrast to this, 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 fed efficiently by electromagnetic induction.

[0094] 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.

[0095] By adopting the above-described range of the transmission gap G, power range, and frequency band, not only can the temperature rise in 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 transmission 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 wireless power feeding using the magnetic field resonance method in the above frequency band.

[0096] [Additional Form 15] FIGS. 14A and 14B are diagrams showing overlap patterns of the tire radial direction positions of the power transmitting coil 52 and the tire radial direction positions of the power receiving coil 40 for the wireless power feed system 50 according to this embodiment, in which (A) shows an example in which the tire radial direction outer portion of the power transmitting coil 52 and the tire radial direction inner portion of the power receiving coil 40 overlap, and (B) shows an example in which the tire radial direction inner portion of the power transmitting coil 52 and the tire radial direction outer portion of the power receiving coil 40 overlap.

[0097] 14A and 14B , in a meridian cross section of the tire, 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 ends of the power transmitting coil 52 (Additional Mode 15). Here, the positional relationship in the tire radial direction between the power receiving coil 40 and the power transmitting coil 52 is measured with the tire 10 mounted on a rim and pressurized to the normal internal pressure, mounted on a vehicle, and stopped on flat ground.

[0098] 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 any component constituting the strut structure. For this reason, 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 14(A) and 14(B) .

[0099] Based on this knowledge, when the power supply direction Dp is set to be approximately the tire width direction, as shown in Figures 14(A) and 14(B), power supply can be performed more efficiently, and ultimately excellent transmission efficiency can be achieved.

[0100] Furthermore, in the examples shown in Figures 14(B) and (C), the constituent surfaces (planes normal to the winding axes of each coil in Figures 14(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 14(A) and (D), and superior transmission efficiency can be achieved.

[0101] 14A and 14D, 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 electromagnetic induction, and there are no restrictions on the relative orientation of the surfaces.

[0102] Additional Embodiment 16 FIG. 15 is a diagram showing the installation position of the power transmitting coil 52 in a wireless power supply system 50 according to this embodiment.

[0103] In basic form 14 or a form obtained by adding additional form 15 to basic form 14, as shown in FIG. 15 , it is preferable that the power transmission coil 52 be installed within a range of 60° on both sides of the tire circumferential direction, with an imaginary line extending vertically upward from the tire center O as the center (additional form 16).

[0104] 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 accordance with the tire deformation in a portion of the tire 10 away from the contact portion thereof (the upper portion of the tire 10 in FIG. 15 ). 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 tire's contact portion (a tire circumferential range of 60° on both sides of an imaginary line extending vertically upward from the tire center O), 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 transmission efficiency. Note that the example shown in FIG. 15 is an example in which the power transmitting coil 52 is attached to a wheel well 54, and the above-described tire circumferential range is applied within the wheel well 54.

[0105] It is more preferable that the power transmission coil 52 be installed within a circumferential range of 55° on either side of an imaginary line extending vertically upward from the center of the tire, and it is extremely preferable that the power transmission coil 52 be installed within a circumferential range of 50° on either side of the imaginary line.

[0106] 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.

[0107] [Additional Embodiment 17] FIGS. 16 and 17 are diagrams showing positions where power transmission coils are installed in the tire shown in FIG. 1 .

[0108] In the basic configuration 14 or the configuration in which at least one of additional configurations 15 and 16 is added to the basic configuration 14, the power transmission coil 52 is preferably installed in an unsprung member of the vehicle (additional configuration 17).

[0109] The unsprung member includes, for example, a knuckle, a brake caliper, and a damper case of a strut suspension. By providing the power transmitting coil 52 in the unsprung member, the distance between the power transmitting coil 52 and the power receiving coil 40 provided in the tire 10 can be kept constant even when the vehicle moves up and down due to unevenness in the road surface.

[0110] As shown in Figures 16(A) and 16(B), the power transmitting coil 52 may be provided in a damper case 60 of a strut suspension. Figure 16(A) shows an example in which the power transmitting coil 52 is provided in a front wheel damper case 60, and Figure 16(B) shows an example in which the power transmitting coil 52 is provided in a rear wheel damper case 60. As a result, even when the tire 10 moves up and down due to unevenness in the road surface, the power transmitting coil 52 faces the power receiving coil 40 in the tire width direction, and can 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.

[0111] 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 the knuckle of a multi-link suspension. FIG. 17 shows a front wheel of a multi-link suspension, in which the knuckle 70 rolls together with the tire 10 relative to the upper arm 72 in response to steering. 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.

[0112] <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.

[0113] The carbon content of the inner liner 12 of the tire 10 shown in FIG. 1 is preferably 45 to 75 parts by weight (weight parts when the rubber is 100, the same applies below), the carbon content of the side tread is 25 to 65 parts by weight, the carbon content of the rim cushion is 60 to 90 parts by weight, the carbon content of the bead filler 16 is 40 to 80 parts by weight, the carbon content of the covering rubber of the carcass 18 is 35 to 70 parts by weight, and the carbon content of the run-flat liner is 45 to 75 parts by weight. By adopting these respective carbon content amounts, it is possible to achieve the desired relative dielectric constant in each rubber layer while achieving the tire performance described above. While the relative dielectric constant of rubber is usually determined by the polymer type and compounding ingredients, adjusting the carbon content is most preferable because it is easy to change the electrical properties (because the carbon particles themselves are highly conductive) and easily achieve the rubber properties required for the tire.

[0114] 13 , the power receiving coil 40 is preferably provided in the tire cavity of the sidewall portion B of the tire 10 with its power receiving surface facing in the tire width direction. As described above, when the transmission direction of the power transmitting coil 52 is set to be approximately the tire width direction, as shown in FIGS. 14( a) and 14(b), the power receiving coil 40 is provided with its power receiving surface facing in the tire width direction, so that the power transmitting surface of the power transmitting coil 52 and the power receiving surface of the power receiving coil 40 become parallel. This allows for more efficient power feeding, and ultimately achieves excellent transmission efficiency.

[0115] Figure 18 shows an arrangement of the receiving coil 40 (similar to Figure 6 (A), in which the receiving coil 40 is not continuous in the tire circumferential direction), and (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 relative to the tire radial direction.

[0116] 18(A) to 18(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, the tire 10 repeatedly deforms and releases 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 of the divided regions, it is possible to prevent the power receiving coil 40 from peeling off from the tire inner circumferential surface.

[0117] FIG. 19 is a meridian cross section of the tire (half in the tire width direction) showing a power supply mode in which power is supplied from the power receiving coil 40 to an electronic device 47 attached to the tire cavity surface via a power line 45 in the tire 10 shown in FIG. 1 .

[0118] As shown in the figure, the power receiving coil 40 is connected to a capacitor (not shown) as a resonant circuit, and supplies power to an electronic device 47 (sensor, signal processing circuit, communication corridor, etc.) attached to the tire cavity surface via a power line 45 attached to the tire cavity surface. The electronic device 47 is less resistant 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 47 is located 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 located 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 45. This allows the power received by the power receiving coil 40 to be supplied to the electronic device 47 with low loss and high power supply efficiency, while ensuring the durability of the electronic device 47. Furthermore, by arranging all of these components (the power receiving coil 40, the capacitor, the power line 45, and the electronic device 47) on the tire cavity surface, increases in the manufacturing cost and difficulty of manufacturing the tire 10 are suppressed.

[0119] 2. Second Embodiment A second embodiment of a tire according to the second invention (Basic Embodiment 2 and Additional Embodiments 18 to 22 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 what is obvious to a person skilled in the art.

[0120] [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. 1 is a meridian cross-section of a tire according to this embodiment, showing one side in the tire width direction, with the tire equatorial plane (not shown) as the reference. Note that 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 the normal load is applied (the same applies hereinafter to tire inventions).

[0121] 20 , a tire 10A 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 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.

[0122] Additionally, a rim cushion 24 is provided further outward in the tire width direction from a 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 second filler 25 is provided between the rim cushion 24 and the folded-up portion 18b. A side tread 26, wing tips 28, and a cap tread 30 are provided, in this order, on the tire radially outer side of the rim cushion 24. A bead reinforcing layer 31 is provided in the bead portion A, which is folded back at a bead toe 33 from the inner circumferential side of the tire and extends to a radially intermediate portion of the bead filler 16 on the outer circumferential side of the tire.

[0123] In the tire 10A 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.

[0124] 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 triangular shape as shown in Fig. 20, 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.

[0125] 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 has 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 10A according to the present 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, organic fibers such as rayon, polyester, polyamide, and aramid can be used as the non-magnetic material.

[0126] 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. 20) 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.

[0127] The belt cover 22 is a component that reinforces the tightening effect of the belt 20 on the carcass 18 and is a component 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. 20 ) stacked in the tire radial direction on the tire radial outer side of the belt 20. Each belt cover layer 22a, 22b is composed of multiple cords coated with rubber. Generally, steel cords or organic fiber cords are used as the cords used in the belt cover layers. These cords can be made of magnetic materials such as steel cords, or non-magnetic materials (including paramagnetic and diamagnetic materials). The bead reinforcing layer 31 is a component that wraps around the folded-up portion 18b of the carcass 18 to contribute to improving the rigidity of the bead portion A and is composed of multiple cords, such as steel cords, coated with rubber. The tire 10A includes a second carcass 29 between the turned-up portion 18b of the carcass 18 and the bead reinforcing layer 31. The second carcass 29 extends from the bead toe 33 to the tread portion D.

[0128] The rim cushion 24 is provided in the area that contacts the rim flange of the 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 area. The second filler 25 is made of a different rubber from the rim cushion 24 and is provided adjacent to the folded-up portion 18b of the carcass 18 as shown in the example. The provision of the second filler 25 appropriately improves the rigidity of the sidewall portion B. The rim cushion 24, second filler 25, side tread 26, wing tips 28, and cap tread 30 can all be made of conventional rubber materials depending on the required characteristics of each.

[0129] Assuming the presence of the components 12 to 30 of the tire 10A described above, the tire 10A according to this embodiment includes a power receiving coil 40 ( FIG. 20 ) 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 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, although the fixing portion may be made of a rubber with a relatively high thermal conductivity, such as silicone rubber) ( FIG. 20 ).

[0130] In power supply using tire 10A 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 power receiving coil 40, generating an induced electromotive force in power receiving coil 40, thereby supplying power.

[0131] To achieve this power supply, in the tire 10A according to this embodiment, in a tire meridian cross section ( FIG. 20 ), the power receiving coil 40 is provided in a region WH in the tire radial direction from the outermost position P1 in the tire radial direction of the bead core 14 to the innermost position P2 in the tire radial direction of the belt 20. The power receiving coil 40 is also provided in a region outward in the tire width direction from the innermost position P2 in the tire radial direction.

[0132] More specifically, the tire radial region WH is a region in the tire radial direction defined by the radially outer end (point P1) of the bead core 14, which may include a ferromagnetic material, and the innermost position in the tire radial direction of the belt 20, which may include a ferromagnetic material (point P2, the outer end of the belt 20 in the tire width direction). The region is outer in the tire radial direction than point P1 and inner in the tire radial direction than point P2. Note that in the tire radial region WH, the tire 10A is curved in an outwardly convex shape. Therefore, when the power receiving coil 40 is provided in the tire radial region WH, the power receiving coil 40 is basically positioned outer in the tire width direction than the outer end (point P2) of the belt 20 in the tire width direction. However, if point P1 is clearly more inward in the tire width direction than point P2 and the power receiving coil 40 is positioned near the bead core 14, there may be cases in which the power receiving coil 40 is positioned inner in the tire width direction than the width direction end (point P2) of the belt 20. Furthermore, if point P1 is clearly located further outward in the tire width direction than point P2 and the receiving coil 40 is positioned near the belt 20, it may be located further inward in the tire width direction than the radially outer end (point P1) of the bead core 14.

[0133] The tire sidewall is the tire surface visible from the outside on the side opposite the tire cavity surface in the tire radial region WH. The outer layer rubber exposed on the tire sidewall contains 0.5 to 8.0 parts by mass of antioxidant per 100 parts by mass of rubber, and 0.1 to 5.0 parts by mass of wax per 100 parts by mass of rubber. In this embodiment, the outer layer rubber exposed on the tire sidewall includes the rim cushion 24, side tread 26, and wing tips 28. That is, at least a portion of the rim cushion 24, side tread 26, and wing tips 28 are each exposed on the tire sidewall, and contain 5.0 to 8.0 parts by mass of antioxidant per 100 parts by mass of rubber, and 0.1 to 5.0 parts by mass of wax per 100 parts by mass of rubber.

[0134] Generally, rubber may deteriorate and crack when exposed to ultraviolet light and oxygen atmosphere. However, by including an antioxidant and wax in rubber, deterioration and cracking can be suppressed.

[0135] Tire 10A contains 0.5 parts by mass or more of antioxidant per 100 parts by mass of rubber and 0.1 parts by mass or more of wax per 100 parts by mass of rubber, thereby suppressing rubber deterioration and crack occurrence. Meanwhile, the tire contains 8.0 parts by mass or less of antioxidant and 5.0 parts by mass or less of wax per 100 parts by mass of rubber, respectively, thereby suppressing precipitation of the antioxidant and wax on the tire sidewalls over time.

[0136] The antioxidant is preferably an amine-based antioxidant, such as alkylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, p-(p-toluenesulfonylamido)diphenylamine, or N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine.

[0137] The antioxidant content can be measured, for example, by gas chromatography in accordance with JIS K6229 and JIS K0114, as shown below. That is, an unused new tire is disassembled, and the outer layer rubber is thinly sliced ​​and then cut into test pieces approximately 1 mm square and 30 mm long. The pieces are extracted with acetone for 8 hours, and the resulting filtrate is returned to room temperature to prepare a gas chromatographic measurement sample. Furthermore, solutions (standard samples) containing the antioxidant to be measured at four different concentrations ranging from 100 ppm to 1000 ppm are prepared. The area of ​​the resulting gas chromatographic measurement sample is then determined, and the antioxidant content in the gas chromatographic measurement sample is calculated using a calibration curve.

[0138] Wax refers to a substance that is malleable at ambient temperature, has a relatively low viscosity when melted, is insoluble in water, and is hydrophobic. Examples of wax include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0139] The wax content can be measured, for example, by a method conforming to JIS K6229, as shown below. That is, an unused new tire is disassembled, and the outer layer rubber is thinly sliced ​​and then cut into test pieces approximately 1 mm square and 30 mm long. These are extracted with acetone for 8 hours, and the resulting filtrate is cooled (to a temperature <0°C) to precipitate the wax. The wax content is then determined from the weight of the precipitate and the weight of the sample.

[0140] (Operation, etc.) As described above, a wireless power receiving system is known in the prior art that supplies power between a power transmitting coil buried near the road surface and a power receiving coil attached to the center line of a wheel in the tire width direction (see Patent Document 1, FIG. 20). In this wireless power receiving system, the magnetic field that reaches the power receiving coil from the power transmitting coil may be affected by the belt. For example, if a belt cord made of metal (limited to magnetic material) is used in this wireless power receiving system, part of the magnetic field that would otherwise reach the power receiving coil from the power transmitting coil may be blocked by the magnetic material (belt cord) included in the belt, which may result in poor power supply efficiency.

[0141] Therefore, the inventors have conducted extensive research into a tire 10 that can achieve excellent power supply efficiency, even when a metal belt cord is used for the belt 20 shown in FIG. 20 , without blocking part of the magnetic field that would otherwise reach the power receiving coil 40 from the power transmitting coil by components of the tire 10 that contain magnetic material present between the two coils.

[0142] Specifically, the inventors conducted extensive research into the best position for forming the receiving coil 40, which is provided on the inner side of the tire 10 in the tire width direction, relative to the transmitting coil (not shown) provided outside the tire 10.

[0143] First, the inventors focused on the multiple line segments in Figure 20 that reach each point (starting point) on the tire cavity surface 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 from among these line segments, and discovered that by positioning the power receiving coil 40 so that it does not deviate from the tire cavity surface included in this region, most of the magnetic field generated between the two coils will not be blocked by the belt 20, which may contain magnetic material.

[0144] 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.

[0145] Based on the above findings, in the tire 10 according to this embodiment, the power receiving coil 40 is provided in a region WH in the tire radial direction from the outermost position P1 in the tire radial direction of the bead core 14 to the innermost position P2 in the tire radial direction of the belt 20. As a result, in the tire 10 according to this embodiment, an excessive number of components of the tire 10 that may contain magnetic material are not provided between the power transmitting coil and the power receiving coil 40, thereby improving power supply efficiency.

[0146] Next, when the tire is rolling, iron powder is generated from the brake rotor and brake pads due to braking. In wireless power receiving systems, iron powder can block part of the magnetic field that should reach the power receiving coil from the power transmitting coil. Therefore, we conducted extensive research into ways to reduce the impact of iron powder generated from the brake rotor and brake pads on the power receiving system.

[0147] Specifically, the inventors have found that as tires age, antioxidants and wax contained in rubber precipitate on the tire surface, and that iron powder generated from the brake rotors and brake pads tends to adhere to the precipitated antioxidants and wax.

[0148] Based on the above findings, the tire 10 according to the present embodiment has the antioxidant and wax contained in the outer layer rubber limited to 0.5 to 8.0 parts by mass per 100 parts by mass of rubber and 0.1 to 5.0 parts by mass per 100 parts by mass of rubber, respectively. By limiting the antioxidant and wax contents in the outer layer rubber to the above ranges, the tire 10 can suppress the amount of antioxidant and wax precipitation while maintaining the performance of the outer layer rubber. As a result, the tire 10 according to the present embodiment suppresses the amount of antioxidant and wax precipitation on the tire sidewall, making it less likely for iron powder to adhere to the tire sidewall. Therefore, the tire 10 suppresses the decline in power supply efficiency for transmitting electric power even with long-term use.

[0149] The antioxidant is contained in an amount of preferably 0.7 to 7.8 parts by mass, and most preferably 0.8 to 7.5 parts by mass, per 100 parts by mass of rubber, and the wax is contained in an amount of preferably 0.2 to 4.8 parts by mass, and even more preferably 0.3 to 4.5 parts by mass, per 100 parts by mass of rubber.

[0150] FIG. 21 is a meridian cross-sectional view showing a modified example of the tire according to this embodiment. In this embodiment, a tire 10B shown in FIG. 21 can be used instead of the tire 10A shown in FIG. 20. As shown in FIG. 21, the tire 10B is a run-flat tire in which a run-flat liner 27 is provided on the tire width direction outer side of the inner liner 12, mainly in the sidewall portion B. The run-flat liner 27 is formed between the inner liner 12 and the carcass 18, extending over at least the sidewall portion B and the shoulder portion C. Note that even when the run-flat liner 27 is provided, the power receiving coil 40 can be provided on the inner peripheral side of the inner liner 12. In the example shown in FIG. 21, the carcass 18 is made up of two carcass plies 19a and 19b. The carcass ply 19a terminates at the upper part of the run-flat liner 27 in the tire radial direction, while the carcass ply 19b terminates at the center of the bead filler 16 in the tire radial direction.

[0151] In both of the tires 10A and 10B shown in FIGS. 20 and 21 , the power receiving coil 40 may be provided on the tire cavity surface via a support layer (not shown) provided between the power receiving coil 40 and the tire cavity surface (composed of the inner liner 12). The support layer is a plate-shaped member having a predetermined thickness and is formed of an insulating material, such as rubber or synthetic resin. The outer side of the support layer in the tire width direction may be bonded to the inner liner 12 with an adhesive. The power receiving coil is provided on the inner side of the support layer in the tire width direction. The power receiving coil may be bonded to the support layer with an adhesive. In another example, the power receiving coil 40 may be covered with a covering layer. The covering layer may be formed of the same material as the support layer, or may be formed of a different material. In this case, the support layer, the power receiving coil 40, and the covering layer are arranged in this order from the outer side in the tire width direction to the inner side in the tire width direction, and are integrated with the tire cavity surface. The power receiving coil 40 is sandwiched between the support layer and the covering layer. In another example, the receiving coil 40 may be embedded in the support layer. In this case, the support layer has a thickness sufficient to cover the receiving coil 40.

[0152] (Additional Mode 18) In Basic Mode 2, the thickness t of the outer layer rubber is preferably 2.5 to 20.0 mm (Additional Mode 18), more preferably 2.7 to 18.0 mm, and extremely preferably 2.9 to 16.0 mm. The outer layer rubber in the tire radial region WH includes the rim cushion 24, the side tread 26, and the wing tips 28. As shown in FIG. 20 , the thickness t of the outer layer rubber refers to the length in the direction perpendicular to the outer surface of the carcass 18 in the tire width direction, i.e., the outer surface of the folded-up portion 18b in the tire width direction. The thickness t of the outer layer rubber varies in the tire radial direction, as shown in FIG. 20 . In other words, it is preferable that the thickness t of the outer layer rubber is within the above range at every point.

[0153] In tire 10A, by having the thickness t of the outer layer rubber within the above range, the tire can maintain the performance of the outer layer rubber while preventing the contents of antioxidant and wax from becoming excessive, and more reliably suppressing the amounts of precipitation of antioxidant and wax.

[0154] In the tire 10A, if the thickness t of the outer layer rubber is too large, the content of antioxidant and wax in the outer layer rubber as a whole becomes excessive. On the other hand, in the tire 10A, if the thickness t of the outer layer rubber is too small, it becomes difficult to maintain the performance of the outer layer rubber.

[0155] (Additional Embodiment 19) Fig. 22 is a meridian cross-sectional view illustrating the amount of deflection in the tire width direction of the tire according to this embodiment. In Basic Embodiment 2 or an embodiment in which Additional Embodiment 18 is added to Basic Embodiment 2, as shown in Fig. 22, in a tire 10A mounted on a standard rim and pressurized to a normal internal pressure, it is preferable that the length SH (mm) in the tire radial direction from the bead toe 33 to the tread surface 34 of the tire 10A in an unloaded state and the amount of deflection D in the tire width direction before and after applying a load corresponding to 80% of the normal load to the tire 10A satisfy the following formula (2) (Additional Embodiment 19): 0.0278 x SH - 1.33 ≤ D ≤ 0.286 x SH - 13.7 (2)

[0156] The meridian cross section shown by the dashed line in Figure 22 shows the tire 10A in an unloaded state when mounted on a standard rim and pressurized to a normal internal pressure. The tire radial length (also referred to as the tire cross-sectional height) from the bead toe 33 to the tread surface 34 at the contact center when unloaded is defined as SH (mm). The tire widthwise length when unloaded is defined as D1. The meridian cross section shown by the solid line in Figure 21 shows the tire 10A mounted on a standard rim and pressurized to a normal internal pressure after a load corresponding to 80% of the normal load has been applied. The tire widthwise length at the contact center after a load corresponding to 80% of the normal load has been applied is defined as D2.

[0157] The amount of deflection D in the tire width direction before and after applying a load corresponding to 80% of the normal load to the tire is the difference (D2-D1) between the tire width direction length D1 in an unloaded state and the tire width direction length D2 after applying a load corresponding to 80% of the normal load.

[0158] In the tire 10A, in a tire meridian cross section, of the rubber arranged in the tire radial region WH, preferably 6% or more of the cross-sectional area of ​​the tire radial region WH has a JIS hardness of 65 or more, more preferably 8% or more, and extremely preferably 10% or more. The rubber arranged in the tire radial region WH includes the bead filler 16, the rim cushion 24 (second filler 25), and the side tread 26. The JIS hardness is a durometer hardness measured in accordance with JIS-K6253 using a durometer type A at a temperature of 23°C.

[0159] In the tire 10A, the deflection amount D is within the range expressed by the above formula (2), so that tire performance is maintained during tire rolling, and deformation of the tire side surface, centered on the sidewall portion B, is suppressed. By suppressing deformation of the tire side surface, the tire 10A can suppress precipitation of antioxidants and wax from the rubber on the tire side surface.

[0160] If the tire 10 has an excessively large deformation amount on the tire side surface, i.e., if the tire 10 is easily deformed, repeated deformation will likely cause antioxidants and wax to precipitate from the rubber on the tire side surface. Also, if the tire side surface has an excessively large deformation amount, the power receiving coil provided on the tire cavity surface in the tire radial direction region WH will likely fall off from the tire cavity surface.

[0161] In the above formula (2), the deflection amount D is more preferably 0.0278×SH−1.31≦D, and extremely preferably 0.0278×SH−1.29≦D. Similarly, the deflection amount D is more preferably D≦0.286×SH−13.9, and extremely preferably D≦0.286×SH−14.1.

[0162] (Additional Form 20) In the basic form 2 or the form in which at least one of the additional forms 18 and 19 is added to the basic form 2, the cross-sectional area S of the outer layer rubber ｏ and 100% modulus M ｏ and the cross-sectional area S of the inner layer rubber that is arranged inside the outer layer rubber in the tire width direction and is not exposed to the tire sidewall. ｉ and 100% modulus M ｉ It is preferable that the sum of the products of and satisfy the following formula (3) (Additional Form 20).

[0163]

[0164] The cross-sectional area is the cross-sectional area of ​​the rubber in a meridian section. The inner layer rubber is the bead filler 16 and the second filler 25. The inner layer rubber does not include the inner liner 12 and the carcass 18. In the tire of FIG. 20, the cross-sectional area S ｏｋ is the cross-sectional area S of the rim cushion 24 within the tire radial direction region WH ｏ１ , the cross-sectional area S of the side tread 26 ｏ２ and the cross-sectional area S of the wing tip 28 ｏ３ The cross-sectional area of ​​the inner rubber layer S ｉｋ is the cross-sectional area S of the bead filler 16 in the range of the tire radial direction region WH ｉ１ and the cross-sectional area S of the second filler 25 ｉ２ is.

[0165] The 100% modulus is the tensile stress when 100% elongation is applied. The 100% modulus can be measured by the following procedure. First, JIS No. 3 dumbbell-shaped test pieces are cut out from rubber test pieces obtained from various parts of the tire in accordance with JIS K6251. Next, the 100% deformation stress is measured in accordance with JIS K6251. The 100% deformation stress is taken as the measured value of the 100% modulus.

[0166] 100% modulus M of outer rubber ｏｋ is the measurement value M of the rim cushion 24 ｏ１ , the measurement value M of the side tread 26 ｏ２ and the measurement value M of the wingtip 28 ｏ３ The 100% modulus M of the inner layer rubber ｉｋ is the measured value M of the bead filler 16 ｉ１ and the measurement value M of the second filler 25 ｉ２ is.

[0167] The cross-sectional area S of the outer layer rubber in the above formula (3) ｏ and 100% modulus M ｏ The sum of the products of these is the load required for the outer rubber layer to deform 100% (hereinafter referred to as the "outer rubber load"). ｉ and 100% modulus M ｉ The sum of the products of these is the load required for the inner layer rubber to deform 100% (hereinafter referred to as the "inner layer rubber load"). The value obtained by dividing the inner layer rubber load by the outer layer rubber load is referred to as the load index in this specification.

[0168] By having the load index within the range of the above formula (3), the tire can suppress deformation of the tire sidewall, suppress deposition of antioxidants and wax from the rubber on the tire sidewall, and ensure cut resistance of the outer layer rubber. If the load index is below the above range, the rigidity of the inner layer rubber will be insufficient, resulting in excessive tire deformation, or the volume of the outer layer rubber will be excessively large, resulting in increased deposition of antioxidants and wax. On the other hand, if the load index is above the above range, the thickness of the outer layer rubber will be too small, resulting in reduced cut resistance of the tire sidewall.

[0169] When the load index satisfies the above formula (3), tire performance during tire rolling is maintained while deformation of the tire side surface, centered on the sidewall portion B, is suppressed. Therefore, the amount of deformation of the tire 10 is suppressed while maintaining the function of the tire 10, and therefore the amounts of precipitation of the antioxidant and wax can be suppressed.

[0170] The load index value is more preferably 0.35 or greater and 6.5 or less, and most preferably 0.4 or greater and 6.0 or less. In the case of a tire 10A including a run-flat liner 27 shown in Figure 21, the inner layer rubber is made up of a bead filler 16, a second filler 25, and the run-flat liner 27.

[0171] (Additional Configuration 21) In Basic Configuration 2 or a configuration in which Basic Configuration 2 is combined with at least one of Additional Configurations 18 to 20, the height of the irregularities on the surface of the outer rubber layer is preferably 2.0 mm or less (Additional Configuration 21).

[0172] The tire 10A may have unevenness, such as stamping, commemorative markings, serrations, and decorative patterns, on the surface of the outer rubber layer, i.e., the tire sidewall. The height of the unevenness formed on the surface of the outer rubber layer (tire sidewall) of the tire 10A is 2.0 mm or less. The unevenness is a surface shape having peaks and valleys. The height of the unevenness refers to the length in the thickness direction of the outer rubber layer between the position where the peak height is greatest and the position where the valley depth is greatest. Because the height of the unevenness of the tire 10A is 2.0 mm or less, iron powder is less likely to accumulate in the uneven portions. Therefore, the tire 10A is prevented from adhering to the uneven portions of the tire sidewall. Note that lug grooves (not shown) formed in the shoulder regions C are not included in the unevenness. Because the shoulder regions C are near the belt 20, even if iron powder accumulates in the lug grooves formed in the shoulder regions C, the impact on power supply efficiency is small.

[0173] (Additional Mode 22) In Basic Mode 2 or a mode in which at least one of Additional Modes 18 to 21 is added to Basic Mode 2, the power receiving coil 40 generates power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil 40, and in a power receiving coil radial direction region R1 whose length in the tire radial direction is defined by the length between both ends of the power receiving coil 40 in the tire radial direction as viewed in a meridian cross section of the tire ( FIG. 20 ), and in power receiving vicinity regions R2 adjacent to both sides of the power receiving coil radial direction region R1 in the tire radial direction and whose tire radial length is defined as 15% of the tire radial length of the tire radial direction region WH, it is preferable that the outer layer rubber contains 0.5 to 7.5 parts by mass of an antioxidant per 100 parts by mass of rubber and 0.1 to 4.5 parts by mass of wax per 100 parts by mass of rubber, and the height of the irregularities on the surface of the outer layer rubber is 1.5 mm or less (Additional Mode 22).

[0174] In tire 10A, the contents of antioxidant and wax in the outer layer rubber in the power receiving region AR are within the above ranges, thereby enabling the amount of antioxidant and wax deposition to be more reliably suppressed while maintaining the performance of the outer layer rubber. Furthermore, in tire 10A, the height of the projections and recesses on the surface of the outer layer rubber is within the above ranges, making it difficult for iron powder to accumulate in the projections and recesses, thereby more reliably suppressing the adhesion of iron powder to the projections and recesses on the tire sidewall. Therefore, tire 10A more reliably suppresses the adhesion of iron powder to the tire sidewall in the power receiving region AR.

[0175] The outer layer rubber included in the power receiving area AR varies depending on the position where the power receiving coil 40 is installed. In the tire 10A shown in FIG. 20 , the outer layer rubber included in the power receiving area AR is the side tread 26. When the power receiving coil 40 is installed in a position radially outward of the tire from the position shown in FIG. 20 , the outer layer rubber included in the power receiving area AR includes the side tread 26 and wing tip 28. When the power receiving coil 40 is installed in a position radially inward of the tire from the position shown in FIG. 20 , the outer layer rubber included in the power receiving area AR includes the side tread 26 and rim cushion 24. When the power receiving coil 40 is installed in a range wider in the tire radial direction than the range shown in FIG. 20 , the outer layer rubber included in the power receiving area AR includes the rim cushion 24, side tread 26, and wing tip 28.

[0176] 3. Third Embodiment A third embodiment of a tire according to the present invention (Basic Embodiment 3 and Additional Embodiments 23 to 27 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.

[0177] 23 is a meridian cross-sectional view of a tire according to this embodiment, showing one side in the tire width direction, with the tire equatorial plane (not shown) as the reference. The figure shows the tire portion opposite the contact patch 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 tire inventions).

[0178] 23 , a tire 10C 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 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 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.

[0179] Additionally, 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. Note that the tire according to this embodiment is not limited to the example shown in Fig. 23 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.

[0180] In the tire 10C configured as described above, the inner liner 12 is a layer for blocking gas coming 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 laminated in the tire radial direction at the tire equatorial plane. 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 in contact with the carcass 18 as other layers.

[0181] 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 triangular shape as shown in Fig. 23, 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.

[0182] The carcass 18 is a component forming the framework of the tire 10C 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 10C 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.

[0183] 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. 23) 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.

[0184] 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 (three belt cover layers 22a, 22b, and 22c in the example shown in FIG. 23 ) 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.

[0185] 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.

[0186] Assuming the presence of the components 12 to 30 of the tire 10C described above (and possibly a run-flat liner), the tire 10C according to this embodiment includes, on its inner cavity surface, a power receiving coil 40 ( FIG. 23 ) that receives AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10C. 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.

[0187] In power supply using the tire 10C according to this embodiment, for example, 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 a knuckle or hub carrier, which are components of a steering axle of a vehicle, or to the tire-side surface of any component constituting a strut structure), 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.

[0188] To achieve such power supply, in the tire 10C according to this embodiment, the thermal conductivity λ1 of the inner liner 12 is 0.10 W / m·k or more in the tire radial region CW between both legs of a perpendicular line drawn from each of the tire radial ends of the power receiving coil 40 to the inner liner 12 formed on the inner circumferential side of the carcass 18.

[0189] In this embodiment, the thermal conductivity is measured by the heat flow meter method specified in JIS A1412-2 and ISO 8301, or the laser flash method specified in JIS R1611, or a method specified in other standards equivalent to these methods.

[0190] 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.

[0191] 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 thermal conductivity of at least a predetermined area of ​​the inner liner, even if a temperature rise occurs near the location where the power receiving coil is located during power reception, heat is not locally trapped in the rim-mounted tire, and the power receiving coil is kept well-fixed, thereby achieving excellent power supply efficiency. The specific reasons for selecting the predetermined area of ​​the inner liner to which a specific thermal conductivity is applied and for selecting the range of the thermal conductivity are as follows.

[0192] As described above, an example of a location where the power transmitting coil is installed is the knuckle (not shown), which is a part of the steering axle of a vehicle. This knuckle is usually located on the outer side of the sidewall portion B in the tire width direction (the right side in FIG. 23 ) in FIG. 23 . Therefore, the magnetic field generated between the power transmitting coil and the power receiving coil 40 is generated in the sidewall portion B such that magnetic field lines penetrate the inner surface of the inner liner 12 approximately perpendicularly.

[0193] Furthermore, the power receiving coil 40 generates heat during power supply, but when viewed as a whole, the heat generated by the tire 10C includes heat caused by the power receiving coil 40, heat caused by heat generated by the rubber members as the tire rolls, heat caused by friction between the road surface and the cap tread, etc. In harsh environments where multiple sources of heat generation exist, it is essential to efficiently dissipate the heat generated by the power receiving coil 40.

[0194] 23 , heat dissipation in the inner liner 12 adjacent to the power receiving coil 40, which is a heat source, can be promoted and a temperature rise in the power receiving coil 40 can be suppressed. As a result, heat can be prevented from being trapped locally in the tire 10C, and the power receiving coil 40 and the inner liner 12 can be kept well fixed to suppress deformation of the power receiving coil 40, thereby achieving excellent power supply efficiency.

[0195] Here, the thermal conductivity is more preferably 0.11 W / m·k or more, and most preferably 0.12 W / m·k or more.

[0196] (Additional Form 23) In the basic form 1, it is preferable that the power receiving coil 40 is provided in a tire radial region WH from the tire radial outermost position P1 of the bead core 14 to the tire radial innermost position P2 of the belt 20 in a tire meridian cross section (Figure 23) (additional form 23).

[0197] The aforementioned Patent Document 1 discloses a wireless power receiving system that supplies power between a power transmitting coil buried near the road surface and a power receiving coil attached to the centerline of a wheel in the tire width direction (see FIG. 1 of Patent Document 1). In this wireless power receiving system, the magnetic field that reaches the power receiving coil from the power transmitting coil may be affected by the belt. For example, if a belt cord made of metal (limited to magnetic material) is used in this wireless power receiving system, part of the magnetic field that would otherwise reach the power receiving coil from the power transmitting coil may be blocked by the magnetic material (belt cord) included in the belt, which may result in poor power supply efficiency.

[0198] Therefore, the inventors conducted extensive research into a tire 10C that can achieve excellent power supply efficiency even when a metal belt cord is used for the belt 20 shown in FIG. 23 , without blocking part of the magnetic field that would otherwise reach the power receiving coil 40 from the power transmitting coil by components of the tire 10C that include a magnetic material that is present between the two coils.

[0199] Specifically, the inventors conducted extensive research into the best position for forming the receiving coil 40 provided on the inner cavity surface of the tire 10C relative to the transmitting coil (not shown) provided outside the tire 10C.

[0200] First, the inventors focused on the multiple line segments in Figure 23 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, the majority of the magnetic field generated between the two coils will not be blocked by the belt 20, which may contain magnetic material.

[0201] 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.

[0202] Based on the above findings, in the tire 10C according to this embodiment, the power receiving coil 40 is provided in a region WH in the tire radial direction that extends from the outermost position in the tire radial direction of the bead core 14 to the innermost position in the tire radial direction of the belt 20. As a result, in the tire 10C according to this embodiment, an excessive number of components of the tire 10C that may contain magnetic material are not provided between the power transmitting coil and the power receiving coil 40, and therefore power supply efficiency can be improved.

[0203] (Additional Configuration 24) In Basic Configuration 3 or a configuration in which Additional Configuration 22 is added to Basic Configuration 3, in a tire meridian section (e.g., FIG. 23) cut at a point other than the end of the power receiving coil 40, the total wire cross-sectional area S (m ２ ), the resistance value r (Ω) of the power receiving coil 40 at the frequency of the AC power described above, and the thermal conductivity λ1 (W / m·k) of the inner liner 12 have the following relationship: 1×10 ５ ≦r / (λ1×S)≦8×10 ７ It is preferable that the following condition is satisfied (additional form 24).

[0204] Here, the receiving coil 40 is made of a conductive wire physically connected to a connected circuit (such as a resonant circuit and / or a rectifier circuit), and does not include an independent relay circuit, if any. The resistance value r (Ω) of the receiving coil 40 is a value measured with an impedance analyzer or a network analyzer when AC power of a specific frequency is applied to both ends of the receiving coil 40. Here, the specific frequency refers to the frequency of the AC current generated by the AC power source in the power feeding system; in other words, it refers to the frequency of the power sent to the transmitting coil or the frequency of the AC magnetic field generated across the transmission gap, i.e., the frequency at which wireless power feeding is activated.

[0205] Fig. 24 is a schematic diagram showing the winding pattern of the power receiving coil 40 shown in Fig. 23 in the tire circumferential direction. In a tire meridian section taken along line A-A' shown in Fig. 24, the shape of the power receiving coil 40 is as shown in Fig. 23. In contrast, in a tire meridian section taken in the tire width direction in most of the region X surrounded by the dotted line in Fig. 24 (particularly the central region in the up-down direction of the page), the power receiving coil 40 is longer in the tire width direction than in Fig. 23. For this reason, in this embodiment, the tire meridian section taken in the tire width direction in the region X surrounded by the dotted line in Fig. 24 is excluded.

[0206] Here, [r / (λ1×S)] considered in this embodiment is an index showing the degree of temperature rise in the region including the power receiving coil 40 and the inner liner 12 in the vicinity thereof when heat is generated. That is, the total wire cross-sectional area S (m ２ If the resistance value (r / S) of the receiving coil 40 per unit area (unit: W / m·k) is high, the amount of heat generated is large, resulting in a high temperature rise, and if the thermal conductivity λ1 (W / m·k) of the inner liner 12 is low, heat dissipation is not promoted, resulting in a high temperature rise.

[0207] The upper limit of [r / (λ1×S)] is set to 8×10 ７ By doing as follows, it is possible to suppress the temperature rise during heat generation in the area including the receiving coil 40 and the inner liner 12 in its vicinity, and ultimately to maintain a better fixed state between the receiving coil 40 and the inner liner 12, thereby further improving the durability of the tire 10C.

[0208] In contrast, the total wire cross-sectional area S (m ２ If the total wire cross-sectional area S (m ２ ) is not excessively large, and the lower limit of [r / (λ1×S)] is set to 1×10 ５ By doing so, it is possible to realize good fuel economy and efficient power supply, and in turn, it is possible to realize excellent transmission efficiency.

[0209] The upper limit of [r / (λ1×S)] is 6×10 ７More preferably, it is 4×10 or less. ７ It is highly preferable that the lower limit is 2×10 ５ More preferably, it is 4×10 or more. ５ It is highly preferable that the above be set.

[0210] (Additional Form 25) In Basic Form 3 or a form in which Basic Form 3 is combined with at least one of Additional Forms 23 and 24, it is preferable that the thermal conductivity λ2 of the rubber layers other than the inner liner 12 in the above-mentioned tire radial region WH (the tire radial region from the tire radially outermost position of the bead core 14 to the tire radially innermost position of the belt 20) is 0.13 W / m·k or more (Additional Form 25).

[0211] Here, the rubber layers other than the inner liner 12 include the rim cushion 24, side tread 26, bead filler 16, wing tips 28, run-flat liner (not shown), etc. 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.

[0212] 23 , in a tire radial region WH extending from the sidewall portion B to the nearby bead portion A and shoulder portion C, by setting the thermal conductivity λ2 of the rubber layer to 0.13 W / m·k or more, heat dissipation in this region can be further promoted and the temperature rise of the power receiving coil 40 can be further suppressed. As a result, localized accumulation of heat in the tire 10C can be further prevented, and the fixed state between the power receiving coil 40 and the inner liner 12 can be better maintained, further improving the durability of the tire 10C.

[0213] (Additional Form 26) Figure 25 is a schematic diagram showing a specific example of the installation ratio of the fixing members 41 to the receiving coil 40 shown in Figure 23, [(Σθ2) / θ1], where (A) shows an example in which multiple fixing members 41a are installed at regular intervals, and (B) shows an example in which one fixing member 41b is installed.

[0214] In Basic Configuration 3 or a configuration in which at least one of Additional Configurations 23 to 25 is added to Basic Configuration 3, it is preferable that fixing members 41 (41a, 41b) are provided for fixing the power receiving coil 40 to the tire cavity surface, and the relationship between the ratio [(Σθ2) / θ1] of the sum Σθ2 of the tire circumferential installation angles θ2 of the fixing members to the tire circumferential arrangement angle θ1 of the power receiving coil 40 when the tire center is used as the reference, and the thermal conductivity λ3 (W / m·k) of the fixing members satisfies 0.14×[(Σθ2) / θ1]+0.13≦λ3≦0.38×[(Σθ2) / θ1]+0.42 (Additional Configuration 25).

[0215] In both the examples of Figures 25(A) and (B), the tire circumferential arrangement angle θ1 of the power receiving coil 40 is 360°, so in the examples shown in Figures 25(A) and (B), the above ratio can be written as [(Σθ2) / 360°].

[0216] By setting the thermal conductivity λ3 of the fixing member 41 to a range equal to or greater than the lower limit of the above-mentioned formula, it is possible to suppress the temperature rise of the receiving coil 40, which generates heat when power is supplied, and ultimately to maintain a better fixed state between the receiving coil 40 and the inner liner 12, thereby further improving the durability of the tire 10C.

[0217] In contrast, by setting the thermal conductivity λ3 of the fixing member 41 to a range below the upper limit value of the above-mentioned formula, the fixing member 41 can follow the inner liner 12 well when the tire deforms as the tire rolls, and ultimately the fixed state between the receiving coil 40 and the inner liner 12 can be maintained even better, further improving the durability of the tire 10C.

[0218] In this embodiment, when the power receiving coil 40 is embedded in the inner liner 12 , the inner liner 12 is considered to be the fixing member 41 .

[0219] Furthermore, with regard to the thermal conductivity λ1 of the inner liner 12 and the thermal conductivity λ3 of the fixing member 41, it is preferable from the viewpoint of heat dissipation that λ3 be greater than λ1. The relationship between the thermal conductivities λ1 and λ2 is more preferably λ3 > 1.1 × λ1, and extremely preferably λ3 > 1.2 × λ1.

[0220] 25(A), when multiple fixing members 41a are installed with a gap between them, it is preferable that the angle α between adjacent fixing members in the tire circumferential direction is 35° or less, with respect to the tire center. This configuration reduces frictional heat that may be generated between the wires constituting the power receiving coil 40 and the nearby rubber members in areas where no fixing members 41a are located during tire rotation (vehicle travel), thereby further suppressing heat generation throughout the tire. As a result, the fixed state between the power receiving coil 40 and the inner liner 12 can be maintained more favorably, further improving the durability of the tire 10C.

[0221] The angle between adjacent fixing members in the tire circumferential direction with respect to the tire center is more preferably 33° or less, and most preferably 30° or less.

[0222] (Additional Embodiment 27) Figure 26 is a cross-sectional view showing the wire 42 that constitutes the power receiving coil 40. As shown in the figure, the wire 42 includes an electric wire 42a and a coating layer 42b that coats the electric wire 42a. The electric wire 42a is made of a conductor, and when used in a high-frequency AC circuit as in this embodiment, a conductor with a low resistance value is particularly suitable. Furthermore, when the electric wire 42a is used as a coil that is subjected to a magnetic field, copper is the most suitable non-magnetic metal with low magnetic permeability.

[0223] The covering layer 42b is made of an insulating material, and is preferably made of a resin material when flexibility and workability are both desired. In particular, in this embodiment, the covering layer 42b is preferably made of a resin material such as polyurethane, polyester, polyvinyl formal, polyethylene, nylon, polyvinyl chloride, polyamide-imide, polyester-imide, or polyimide, since high thermal conductivity is desired.

[0224] In basic form 3 or a form in which basic form 3 is combined with at least one of additional forms 23 to 26, the wire 42 constituting the receiving coil 40 includes an electric wire 42a and a coating layer 42b that coats the electric wire 42a, and it is preferable that the thermal conductivity λ4 (W / m·k) of the coating layer 42b is greater than the thermal conductivity λ1 (W / m·k) of the inner liner 12, and that the thickness of the coating layer 42b is 10 to 100 μm (additional form 27).

[0225] By making the thermal conductivity λ4 (W / m·k) of the coating layer 42b greater than the thermal conductivity λ1 (W / m·k) of the inner liner 12 and / or by setting the thickness of the coating layer 42b to 100 μm or less, it is possible to more efficiently promote dissipation of heat generated in the electric wire 42a to the inner liner 12 via the coating layer 42b. This further improves the fixed state between the power receiving coil 40 and the inner liner 12, thereby further improving the durability of the tire 10C. Note that the thermal conductivity λ4 of the coating layer 42b is preferably 0.15 (W / m·k) or more in order to further promote the above-mentioned heat dissipation, more preferably 0.16 (W / m·k) or more, and most preferably 0.17 (W / m·k) or more. Similarly, the thickness of the coating layer 42b is preferably 90 μm or less in order to further promote the above-mentioned heat dissipation, and most preferably 80 μm or less.

[0226] In contrast, by setting the thickness of the coating layer 42b to 10 μm or more, it is possible to ensure the formability of the wire 42 and also to guarantee the durability of the wire 42 itself, thereby improving the durability of the tire 10C itself. This effect is further enhanced by setting the thickness of the coating layer 42b to 12 μm or more, and extremely enhanced by setting the thickness to 15 μm or more.

[0227] 1. First Example Below, a comparison of the effects of the first invention defined in claims 1 to 13 of the present application corresponding to the first embodiment (hereinafter referred to as "Invention Examples 1-1 to 1-13") will be described. Note that, as mentioned above, the difference in the effects of the present application is clear structurally, and therefore a comparison between Invention Examples 1-1 to 1-13 and the conventional example (the example described in Patent Document 1) will not be specifically described.

[0228] The tire size was 245 / 40R19 (specified by JATMA), and wireless power transfer systems 50 (Invention Examples 1-1 to 1-13) shown in Fig. 13 were fabricated to investigate the efficiency of power transfer from the power transmitting coil 52 to the power receiving coil 40. The conditions of the tires 10 included in each of the wireless power transfer systems 50 of Invention Examples 1-1 to 1-13 are as shown in Tables 1-1 and 1-2 below.

[0229]

[0230]

[0231] For the wireless power transfer systems of Examples 1-1 to 1-13 thus fabricated, the ratio (power transmission efficiency) of power 2 received by the receiving coil 40 (and the capacitor resonant circuit) to power 1 transmitted from the transmitting coil 52 was measured, and these ratios were 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 shown in Tables 1-1 and 1-2. In this specification, a ratio of transmitted power (power transmission efficiency) of 95 or higher is considered to be good.

[0232] According to Tables 1-1 and 1-2, it can be seen that all of the wireless power supply systems within the technical scope of the present invention exhibit an excellent ratio of electromagnetic waves after transmission, and therefore achieve excellent power supply efficiency.

[0233] 2. Second Example Below, we will describe a comparison of the effects of the second invention (hereinafter referred to as "Invention Examples 2-1 to 2-9") defined in the claims of the present application corresponding to the second embodiment. Note that, as for a comparison between Invention Examples 2-1 to 2-9 and the conventional example (the example described in Patent Document 1), as mentioned above, the difference in the effects of the present application is clear from the structure, so we will not particularly compare them.

[0234] The tire size was set to 245 / 40R19 (specified by JATMA), and the tire shown in Fig. 20 was manufactured. The conditions of the tires 10 of Examples 2-1 to 2-9 are as shown in Table 2 below.

[0235]

[0236] In Table 2, the antioxidant, wax, thickness of the outer rubber layer, deflection D, value calculated by formula (3) (load index), and height of unevenness conform to the definitions described in this specification.

[0237] For the wireless power transfer systems using the tires of Examples 2-1 to 2-9 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 these ratios were expressed as an index with Example 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 2. The amount of deposition and the presence or absence of cracks were evaluated after all tires were mounted on standard rims, inflated to 230 kPa, and mounted on the front wheels of a passenger car (FR sedan) weighing approximately 1,800 kg, and driven 2,000 km. In Table 2, the "Deposition Amount" column indicates, with the amount of deposition of the antioxidant and wax in Example 2-1 used as the reference, whether the amount of deposition was equal to or less than that of Example 2-1, as indicated by "A," and whether the amount of deposition was greater than that of Example 2-1, as indicated by "B." In addition, in the column "presence or absence of cracks," "A" indicates that there was no crack damage, and "B" indicates that there was damage.

[0238] 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.

[0239] 3. Third Example Below, we will describe a comparison of the effects of the present application between the third inventions (hereinafter referred to as "Invention Examples 3-1 to 3-6") defined in the claims of the present application corresponding to the third embodiment. Note that, as mentioned above, the difference in the effects of the present application between Invention Examples 3-1 to 3-6 and the conventional example (the example described in Patent Document 1) is clear from the configuration, so we will not particularly compare them.

[0240] The tire size was 245 / 40R19 (specified by JATMA), and wireless power transfer systems 50 (invention examples 1 to 6) shown in Fig. 13 were fabricated to investigate the efficiency of power transfer from the power transmitting coil 52 to the power receiving coil 40. The various conditions of the tires included in each of the wireless power transfer systems 50 of invention examples 3-1 to 3-6 are as shown in Table 3 below.

[0241]

[0242] In Table 3, the thermal conductivities λ1 to λ4, r, S, θ1, θ2, etc. conform to the definitions described in this specification.

[0243] For the wireless power transfer systems of Examples 3-1 to 3-6 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 these ratios were expressed as an index where Example 3-1 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 3. In this specification, a ratio of transmitted power (power transmission efficiency) of 95 or higher is considered to be good.

[0244] 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.

[0245] REFERENCE SIGNS LIST 10, 10A, 10B, 10C Tire 12 Inner liner 14 Bead core 16 Bead filler 18 Carcass 19 Steel reinforcement (SRF) 20 Belt 22 Belt cover 24 Rim cushion 25 Second filler 26 Side tread 27 Run-flat liner 28 Wing tip 29 Second carcass 30 Cap tread 31 Bead reinforcing layer 32 Run-flat liner 33 Bead toe 34 Tread surface 40 Power receiving coil 40a Power receiving coil element 41 Fixing member 42 Wire 43 Conductive wire 44 Support layer 45 Power line 47 Electronic device 50 Wireless power transfer system 52 Power transmitting coil 54 Wheelhouse 60 Damper case 70 Knuckle 72 Upper arm A Bead portion AR Power receiving area B Sidewall C Shoulder CP Tire equatorial plane CW Tire radial area D Tread Dp Power supply direction G Transmission gap O Tire center R1 Power receiving coil radial area R2 Power receiving vicinity area WH Tire radial area α Tire circumferential angle θ1 Tire circumferential arrangement angle θ2 Tire circumferential installation angle

Claims

1. A tire having a bead core, a bead filler provided radially outside the bead core in the tire diameter direction, a carcass folded around the bead core, and a belt provided radially outside the carcass in the tire diameter direction, the tire comprising a power receiving coil on the inner surface of the tire cavity for receiving power supplied by an alternating magnetic field from outside the tire, wherein in a tire meridian cross-sectional view, the power receiving coil is provided in a tire diameter direction region from the outermost position of the bead core in the tire diameter direction to the innermost position of the belt in the tire diameter direction, and the relative permittivity of the members other than the tread portion arranged in the tire diameter direction region is 3.5 or more and 250 or less. A tire characterized by that.

2. The tire according to claim 1, wherein the relative permittivity of the inner liner is in the range of 8 or more and 90 or less, and the relative permittivity of the carcass is in the range of 4 or more and 20 or less.

3. The tire according to claim 1 or 2, wherein the relative permittivity of the rubber material constituting the side tread is in the range of 3.5 or more and 40 or less, and the relative permittivity of the rubber materials constituting the rim cushion and the bead filler is in the range of 70 or more and 235 or less.

4. The power receiving coil generates power by receiving a magnetic field transmitted from a power transmitting coil arranged outside the tire in the tire width direction of the power receiving coil. In a tire meridian cross-sectional view, a power receiving coil diameter direction region whose length in the tire diameter direction is defined by the length between both ends of the power receiving coil in the tire diameter direction, and adjacent to both sides in the tire diameter direction with respect to the power receiving coil diameter direction region, and the length in the tire diameter direction is defined by 15% of the length in the tire diameter direction of the power receiving coil diameter direction region. In the power receiving vicinity region, a side tread having a relative permittivity in the range of 3.5 or more and 37 or less is arranged and no rim cushion and bead filler are arranged, and the relative permittivity of the rim cushion and bead filler arranged inside the power receiving coil diameter direction region and the power receiving vicinity region in the tire diameter direction is in the range of 70 or more and 250 or less. The tire according to claim 1 or 2.

5. The power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil. In a tire meridian cross-sectional view, in a power receiving coil radial region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction, a side tread having a relative permittivity in the range of 3.5 or more and 37 or less is disposed, and a rim cushion and a bead filler are not disposed. At least a part of a power receiving vicinity region adjacent to both sides in the tire radial direction with respect to the power receiving coil radial region and having a length in the tire radial direction defined by 15% of the length in the tire radial direction of the tire radial region is provided with at least one of a bead filler and a rim cushion having a relative permittivity in the range of 70 or more and 235 or less. The tire according to claim 1 or 2.

6. The power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil. In a tire meridian cross-sectional view, in a power receiving coil radial region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction, a side tread having a relative permittivity in the range of 3.5 or more and 37 or less is disposed, and at least one of a bead filler and a rim cushion having a relative permittivity in the range of 70 or more and 220 or less is disposed. The tire according to claim 1 or 2.

7. The power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil. In a tire meridian cross-sectional view, in a power receiving coil radial region whose length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction, at least one of a bead filler and a rim cushion having a relative permittivity in the range of 70 or more and 200 or less is disposed, and no side tread is disposed. The relative permittivity of the side tread disposed outside the power receiving coil radial region in the tire radial direction is in the range of 3.5 or more and 40 or less. The tire according to claim 1 or 2.

8. For each member disposed in the tire radial region, the difference in relative permittivity from another member adjacent in the tire width direction is 170 or less. The tire according to claim 1 or 2.

9. The power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil. A member disposed in a power receiving coil radial region defined by the length in the tire radial direction in a tire meridian cross-sectional view and being the length between both ends of the power receiving coil in the tire radial direction has a difference in relative permittivity of 165 or less from another member adjacent in the tire width direction. The tire according to claim 1 or 2.

10. The conductive wire of the power receiving coil is installed on the surface of an inner liner constituting the tire inner cavity surface via a support layer. The relative permittivity of the support layer present between the conductive wire and the inner liner in the tire radial region is lower than the relative permittivity of the inner liner. The tire according to claim 1 or 2.

11. The power receiving coil generates electric power by receiving a magnetic field transmitted from a power transmitting coil disposed outside the tire in the tire width direction of the power receiving coil. In a tire meridian cross-sectional view, at an arbitrary position on a virtual line in the tire width direction within a power receiving coil radial region where the length in the tire radial direction is defined by the length between both ends of the power receiving coil in the tire radial direction, the sum of the product of the relative permittivity of each member and the thickness in the tire width direction, and the shortest distance Dmin from the conductive wire of the power receiving coil to the inner liner is within the range of the formula (1). The tire according to claim 1 or 2.

12. A side support layer is provided on the inner peripheral side of the carcass. The relative permittivity of the side support layer is in the range of 8 or more and 90 or less, and is lower than the relative permittivity of the one with the higher relative permittivity among the rim cushion and the bead filler. The tire according to claim 1 or 2.

13. In a power receiving coil radial region defined by the length in the tire radial direction in a tire meridian cross-sectional view and being the length between both ends of the power receiving coil in the tire radial direction, the maximum value of the thickness of the side support layer in the tire width direction is in the range of 4 mm or more and 12 mm or less. The tire according to claim 12.

14. A wireless power supply system that supplies AC power to a power transmitting coil constituting a resonance circuit by a capacitor and a coil and transmits power to the power receiving coil constituting a resonance circuit by the capacitor and the coil, the wireless power supply system including the tire according to claim 1.

15. In a tire meridian cross-sectional view, at least a part of the power receiving coil is located in a power supply region extending in the winding axis direction of the power transmitting coil across both longitudinal ends of the power transmitting coil. The wireless power supply system according to claim 14.

16. The power transmitting coil is installed within a range of 60° on both sides in the tire circumferential direction centered on an imaginary line extending vertically upward from the tire center. The wireless power supply system according to claim 14 or 15.

17. The power transmitting coil is installed on a spring lower member of a vehicle. The wireless power supply system according to claim 14 or 15.

18. A tire having a bead core, a bead filler provided on the outer side in the tire radial direction of the bead core, a carcass folded around the bead core, and a belt provided on the outer side in the tire radial direction of the carcass, and comprising a power receiving coil on the inner cavity surface of the tire for receiving power supplied by an alternating magnetic field from the outside of the tire, wherein in a tire meridian cross-sectional view, the power receiving coil is provided in a tire radial direction region from the outermost position in the tire radial direction of the bead core to the innermost position in the tire radial direction of the belt, the tire has an outer layer rubber exposed on the tire side surface of the tire radial direction region, the outer layer rubber contains 0.5 to 8.0 parts by mass of an anti-aging agent with respect to 100 parts by mass of the rubber and 0.1 to 5.0 parts by mass of wax with respect to 100 parts by mass of the rubber.

19. A tire having a bead core, a bead filler provided on the outer side in the tire radial direction of the bead core, a carcass folded around the bead core, and a belt provided on the outer side in the tire radial direction of the carcass, and comprising a power receiving coil on the inner cavity surface for receiving power supplied by an alternating magnetic field from the outside of the tire, wherein in a tire meridian cross-sectional view, in a tire radial direction region between both feet of a perpendicular line drawn from each of both ends in the tire radial direction of the power receiving coil to the inner liner formed on the inner peripheral side of the carcass, the thermal conductivity λ1 of the inner liner is 0.10 W / m·k or more.

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