Tire and wireless power supply system

Abstract

To provide a tire which can realize, when a steel cord is used for a belt, excellent power supply efficiency without allowing magnetic field from a power-feeding coil to a power-receiving coil from being disturbed by a metallic component.SOLUTION: A tire includes in a tire meridian cross sectional view: a power-receiving coil (40) which is arranged at a tire radial direction area (WH) from a tire radial direction outermost position (P1) of a bead core (14) to a tire radial direction innermost position (P2) of a belt (20). When a tire radial dimension from a tire radial direction innermost position of the tire (10) to the tire radial direction outermost position of the power-receiving coil is CH, a longitudinal spring constant of the tire is Kv, and air pressure of inside of the tire is P, a following expression is satisfied: 7≤CH / Gr≤95.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, a wireless power reception system has been disclosed that performs power supply between a power transmission coil buried near a road surface and a power reception coil attached on the center line in the tire width direction of a wheel (for example, Patent Document 1, FIG. 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the wireless power reception system of Patent Document 1, since the power reception coil is usually attached to a metal rim portion, the AC magnetic field is affected by the rim portion, and the power that can be received by the power reception coil tends to decrease. On the other hand, when the power reception coil is installed away from the metal rim portion, the power supply efficiency improves, but it has been difficult to dissipate the heat generated by the power reception coil.

[0005] The present invention has been made in view of the above circumstances, and its object is to realize excellent power supply efficiency due to a good fixing mode of the power reception coil at the installation location on the premise that the power reception coil is installed outside the rim portion, and to provide a tire and a wireless power supply system using the tire.

Means for Solving the Problems

[0006] The tire of the present invention has a bead core, a bead filler provided on the tire radial outside of the bead core, a carcass folded around the bead core, and a belt provided on the tire radial outside of the carcass, and has a power receiving coil on the inner cavity surface for receiving power supplied by an alternating magnetic field from the outside of the tire. In a tire meridian cross-sectional view, the deflection index Kv / P (= Gr (mm)) obtained by dividing the vertical spring constant Kv (N / mm) of the tire by the internal air pressure P (kPa) of the tire, and the tire radial dimension CH (mm) from the innermost position in the tire radial direction of the tire to the outermost position in the tire radial direction of the power receiving coil satisfy 7 ≦ CH / Gr ≦ 95.

Advantages of the Invention

[0007] In the tire according to the present invention, on the premise that the power receiving coil is installed outside the rim portion, improvements are made to the fixing mode of the power receiving coil at the installation location. As a result, according to the tire of the present invention, the power supply efficiency can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the tire according to the present invention (basic form 1 and additional forms 2 to 6 shown below), and embodiments of the wireless power feeding system according to the present invention (basic form 7 and additional forms 8 and 9 shown below) will be described in detail with reference to the drawings. Note that these embodiments do not limit the present invention. In addition, the constituent elements of each embodiment include those that can be replaced and are easy for those skilled in the art, or those that are substantially the same. Furthermore, each embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

[0010] In the following description, the tire radial direction refers to the direction orthogonal to the tire rotation axis. The inner side in the tire radial direction refers to the side facing the tire rotation axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. Further, the tire circumferential direction refers to the circumferential direction centered on the tire rotation axis. Furthermore, the tire width direction refers to the direction parallel to the tire rotation axis. The inner side in the tire width direction refers to the side facing the tire equatorial plane (tire equator line) in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane in the tire width direction. Note that the tire equatorial plane refers to a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the tire.

[0011] Similarly, in the following description, the standard rim refers to the "Applicable Rim" defined by JATMA, the "Design Rim" defined by TRA, or the "Measuring Rim" defined by ETRTO.

[0012] Similarly, in the following description, the standard internal pressure refers to the "maximum air pressure" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "INFLATION PRESSURES" defined by ETRTO. Also, the standard load refers to the "maximum load capacity" defined by JATMA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" defined by TRA, or the "LOAD CAPACITY" defined by ETRTO.

[0013] <Tire> [Basic Form 1] FIG. 1 is a meridian cross-sectional view showing one side in the tire width direction with respect to the tire according to the present embodiment, with the tire equatorial plane CP as a reference. In the figure, a tire portion on the side opposite to the ground contact surface is shown in a state where the rim is assembled and the standard internal pressure is applied, and a state where 80% of the standard load is applied (hereinafter, the invention of the tire is the same unless otherwise specified).

[0014] As shown in FIG. 1, a tire 10 according to the present embodiment has a bead portion A, a sidewall portion B, a shoulder portion C, and a tread portion D from the inner side to the outer side in the tire radial direction. In the region from the bead portion A to the tread portion D, an inner liner 12 exposed on the inner cavity surface of the tire is provided. On the side opposite to the inner cavity surface of the inner liner 12, a carcass 18 including a main body portion 18a extending along the inner liner 12 and a folded-back portion 18b folded around the bead core 14 and the bead filler 16 is provided. On the outer side in the tire radial direction of the carcass 18 in the tread portion D, a belt 20 (belt layers 20a, 20b) and a belt cover 22 (belt cover layers 22a, 22b, 22c) are sequentially provided on the outer side in the tire radial direction.

[0015] Further, on the outer side in the tire width direction of the folded-back portion 18b of the carcass 18 provided on the outer side in the tire width direction of the bead core 14 and the bead filler 16, a rim cushion 24 is provided. On the outer side in the tire radial direction of the rim cushion 24, a side tread 26, a wing tip 28, and a cap tread 30 are sequentially provided. Note that the tire according to the present embodiment is not limited to the example shown in FIG. 1, and includes, for example, a run-flat tire in which a run-flat liner is provided on the outer side in the tire width direction of the inner liner 12 mainly in the sidewall portion B.

[0016] In the tire 10 having the configuration shown above, the inner liner 12 is a layer for blocking the gas in contact with the inner cavity surface of the tire. The inner liner 12 can be constituted by a single inner liner layer, or can also be constituted by a plurality of inner liner layers laminated in the tire radial direction at the tire equatorial plane CP. The inner liner 12 includes at least one layer made of a rubber or resin with low air permeability, and as other layers, an adhesive layer can be included at least in the contact portion with the carcass 18.

[0017] The bead core 14 is, for example, a ring-shaped reinforcing material formed by bundling cords, and can have a structure in which a plurality of bead wires made of steel cords or organic fiber cords are coated with rubber. The bead filler 16 is a member for enhancing the rigidity of the bead portion A, and the tire width direction dimension at the radially inner end portion of the tire diameter direction thereof is substantially equal to the tire width direction dimension at the radially outer end portion of the bead core 14, and can have a substantially triangular shape as shown in FIG. 1 in which the tire width direction dimension gradually decreases toward the radially outer side of the tire diameter direction.

[0018] The carcass 18 is a member forming the skeleton of the tire 10, and is composed of at least one carcass layer (carcass ply). Each carcass layer 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 10 according to the present embodiment, as will be described later, in order to prevent the magnetic field generated so as to penetrate substantially perpendicularly to the inner cavity surface of the inner liner 12 in the sidewall portion B from being obstructed by a metal member, it is preferable to use a non-magnetic material as the carcass cord. For example, as the non-magnetic material, organic fibers such as rayon, polyester, polyamide, and aramid can be used.

[0019] The belt 20 is a reinforcing layer provided on the radially outer side of the tire diameter direction of the carcass 18, and is a member that tightens the carcass 18 to enhance the rigidity of the tread portion, improve the handling stability, and reduce the rolling resistance by reducing the strain deformation. The belt 20 can be configured by a plurality of belt layers (two belt layers 20a and 20b in the example shown in FIG. 1) laminated in the tire diameter direction in the tread portion D. Each of the belt layers 20a and 20b has a configuration in which a plurality of belt cords are coated with rubber. Generally, steel cords or organic fiber cords are used as the belt cords. As the belt cord, not only a magnetic material such as a steel cord can be used, but also a non-magnetic material (including a paramagnetic material and a diamagnetic material) can be used.

[0020] The belt cover 22 is a member that reinforces the tightening effect of the carcass 18 by the belt 20, and is particularly a member for preventing the tread portion D from deforming due to the centrifugal force generated during high-speed running of the vehicle. The belt cover 22 can be constituted by a plurality of belt cover layers (in the example shown in FIG. 1, three belt cover layers 22a, 22b, 22c) laminated in the tire diameter direction on the outer side in the tire diameter direction of the belt 20. Each of the belt cover layers 22a, 22b, 22c has a configuration in which a plurality of cords are covered with rubber. Generally, as the cord used for the belt cover layer, a steel cord or an organic fiber cord is used. As this cord, not only a magnetic material such as a steel cord can be used, but also a non-magnetic material (including a paramagnetic material and a diamagnetic material) can be used.

[0021] The rim cushion 24 is provided in a region that contacts the rim flange of a wheel (not shown), and the side dredge 26 is arranged so as to connect the rim cushion 24 and the tread portion D. The wing tip 28 is provided at the boundary between the left and right tread portions D of the tire and the side dredge 26 in a tire meridian cross-sectional view, and the cap tread 30 is formed on the surface of the tread portion D over the entire area of the tire contact surface. The run-flat liner (not shown) is formed on the outer peripheral side of the inner liner 12 over at least the sidewall portion B (in some cases, also including the bead portion A and / or the shoulder portion C). Note that for the rim cushion 24, the side tread 26, the wing tip 28, the cap tread 30, and the run-flat liner, rubber members conventionally used can be used according to their respective required characteristics.

[0022] On the premise of the existence of the components 12 to 30 of the tire 10 shown above (in some cases, including a run-flat liner), the tire 10 according to the present embodiment includes a power receiving coil 40 (FIG. 1) that receives AC power transmitted from a power transmission coil (not shown) installed outside the tire 10 on its inner cavity surface. The power receiving coil 40 may be provided in contact with the inner liner 12 or may be embedded in the inner liner 12. Further, the power receiving coil 40 may 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, and in particular, a rubber having a relatively high thermal conductivity such as silicone rubber can be used for the fixing part). Note that even when a run-flat liner is provided, the power receiving coil 40 can be provided on the inner peripheral side of the inner liner 12 described above.

[0023] For the power supply using the tire 10 according to the present embodiment, for example, a DC current obtained from an in-vehicle battery (not shown) is once converted into an AC current by an AC power supply device, and this AC current is applied to a power transmission coil (for example, attached to the surface of a knuckle or a hub carrier, which are parts of the steering axle of a vehicle, or any part on the tire side of a component constituting a strut structure), thereby generating an AC magnetic field around the power transmission coil. When this AC magnetic field intersects the power receiving coil 40, an induced electromotive force is generated in the power receiving coil 40 and power is supplied.

[0024] In realizing such power supply, in the tire 10 according to the present embodiment, in the tire meridian cross-sectional view, the deflection index Kv / P (= Gr (mm)) obtained by dividing the vertical spring constant Kv (N / mm) of the tire by the air pressure P (kPa) inside the tire, and the tire radial dimension CH (mm) from the innermost position in the tire radial direction of the tire to the outermost position in the tire radial direction of the power receiving coil satisfy 7 ≤ CH / Gr ≤ 95.

[0025] Here, based on the deflection δ50 when a load P50 of 50% of the normal load is applied to the tire 10 with the normal internal pressure applied, and the deflection δ60 when a load P60 of 60% of the normal load is applied, the vertical spring constant Kv (N / mm) of the tire 10 is defined as (P60 - P50) / (δ60 - δ50).

[0026] (Function, etc.) As described above, conventionally, since the power receiving coil was attached to the rim portion made of ordinary metal, the AC magnetic field was affected by the rim portion, and the power that could be received by the power receiving coil tended to decrease (Patent Document 1, FIG. 1). On the other hand, when the power receiving coil was installed apart from the metal rim portion, the power feeding efficiency was improved, but it was difficult to dissipate the heat generated by the power receiving coil.

[0027] Therefore, the inventors of the present invention earnestly studied making the installation location of the power receiving coil a tire component other than a metal member and having as large a surface area (i.e., a region for releasing heat) as possible. As a result, the inventors focused on installing the power receiving coil on the inner liner formed on the inner peripheral side of the carcass, and by appropriately adjusting the ratio Gr / CH of the tire deflection index Gr (mm) to the tire radial dimension CH (mm) shown in FIG. 1, a good fixing mode of the power receiving coil at the installation location was realized, and thus, the knowledge that excellent power feeding efficiency can be realized was obtained. The specific reasons for setting the lower limit value and the upper limit value of the ratio Gr / CH are as follows.

[0028] That is, when the tire 10 is rolled for a long period of time or when the tire 10 is rolled under a situation where the temperature change is drastic, the internal pressure of the tire 10 may decrease. This decrease in the internal pressure causes an increase in the deformation of the tire 10, and as a result, the deformation of the power receiving coil 40 provided on the inner cavity surface of the tire 10 may also increase. In view of such circumstances, the inventors focused on CH / Gr, which is a parameter related to the deformation of the power receiving coil 40, and obtained the knowledge that if the value of this parameter is 95 or less, the rigidity of the tire 10 will not become excessively small, the power receiving coil 40 will not be deformed, and excellent power feeding can be realized.

[0029] Further, the inventors have found that if the value of this parameter is 7 or more, the rigidity of the tire 10 will not become excessively large, and consequently, the impact received by the power receiving coil 40 during the running of the tire 10 will not become excessively large, and excellent durability can be realized in the tire 10.

[0030] Based on the above findings, in the tire 10 according to the present embodiment, as shown in FIG. 1, the value of CH / Gr, which is the above parameter, is set to 7 or more and 95 or less. Thereby, according to the tire 10 according to the present embodiment, based on the range of the upper limit value of the above parameter, the rigidity of the tire 10 will not become excessively small, and the power receiving coil 40 will not be excessively deformed, so that the power supply efficiency can be improved. Further, according to the tire 10 according to the present embodiment, excellent durability performance can also be realized based on the range of the lower limit value of the above parameter. Note that the value of the parameter CH / Gr is preferably 8 or more and 92 or less, and extremely preferably 9 or more and 90 or less.

[0031] Furthermore, in the basic form 1, the inventors have earnestly studied, as an optional matter, at what position the power receiving coil 40 provided on the inner cavity surface of the tire 10 should be formed with respect to a power transmission coil (not shown) provided outside the tire 10 in order to further improve the power supply efficiency.

[0032] First, in FIG. 1, the inventors focused on a plurality of line segments that reach from each point (starting point) on the inner cavity surface of the tire (the same applies when there is a run-flat liner) to each point (ending point) on the outer surface of the tire at the shortest distance, and extracted a region composed of a plurality of line segments that do not include the belt 20 among these line segments. By providing the power receiving coil 40 so as not to deviate from the inner cavity surface of the tire included in this region, it was found that most of the magnetic field generated between the two coils will not be blocked by the belt 20 that may contain a magnetic material.

[0033] Next, in view of the above finding being for defining the radially outer end of the installation region of the power receiving coil 40, the inventors also earnestly studied how to define the radially inner end of this installation region. As a result, the inventors focused on the bead core 14 which may be composed of a metal member, extracted a region composed of a plurality of line segments that do not include the bead core 14 among the above line segments, and provided the power receiving coil 40 so as not to deviate from the inner surface of the tire cavity included in this region. Thus, the inventors also obtained the finding that most of the magnetic field generated between the two coils would not be blocked by the bead core 14 which may contain a magnetic material.

[0034] Based on the above findings, in the tire 10 according to the present embodiment, as shown in FIG. 1, when the power receiving coil 40 is provided in the tire radial region WH (hereinafter, may be referred to as the "tire radial power receiving region WH") from the radially outermost position of the bead core 14 to the radially innermost position of the belt 20, since there is no excessive provision of components of the tire 10 that may contain a magnetic material between the power transmission coil and the power receiving coil 40, the power supply efficiency can be further improved.

[0035] (Additional Form 2) In Basic Form 1, the relationship between the tire radial dimension CH (mm) from the radially innermost position of the tire 10 shown in FIG. 1 to the radially outermost position of the power receiving coil 40, the tire section height SH (mm), and the flatness ratio r (0 < r ≦ 1) of the tire is -0.1r + 0.17 ≦ CH / SH ≦ -0.3r + 0.6 satisfying this (Additional Form 2) is preferable. Note that the tire radial dimension CH (mm) is a value measured by imaging with a CT scan in a state where the tire 10 shown in FIG. 1 is assembled with a rim and a normal internal pressure is applied, and in a non-grounded state.

[0036] Generally, even if the above parameter (CH / SH) is constant, the rigidity of the sidewall portion B varies depending on the aspect ratio r (tire section height / tire section width), and consequently, the degree of deformation of the power receiving coil 40 also differs. Therefore, the aspect ratio r is an important factor in power supply.

[0037] When the aspect ratio r is relatively small, that is, when the tire section height relative to the tire section width is relatively small, the deflection of the sidewall portion B is relatively small under the application of a normal load with a normal internal pressure. On the other hand, when the aspect ratio r is relatively large, that is, when the tire section height relative to the tire section width is relatively large, the deflection of the sidewall portion B under the same conditions is relatively large. In other words, when the aspect ratio r is relatively small, the rigidity of the sidewall portion B is relatively high, and when the aspect ratio r is relatively large, the rigidity of the sidewall portion B is relatively small.

[0038] Therefore, based on the finding that the suitable range of the installation position of the power receiving coil 40 varies depending on the aspect ratio r when considering the rigidity of the sidewall portion B, the present inventors conducted various experiments and obtained the range of the above inequality.

[0039] Specifically, by setting the above parameter (CH / SH) to (-0.3r + 0.6) or less, the deflection that the power receiving coil 40 undergoes during the rolling of the tire 10 does not become excessively large, and the durability of the power receiving coil 40, and consequently, the durability of the tire 10 can be enhanced. It should be noted that the above parameter (CH / SH) is more preferably (-0.3r + 0.58) or less, and extremely preferably (-0.3r + 0.56) or less.

[0040] Next, the inventors further intensively studied a more preferable mounting position of the power receiving coil 40 on the inner cavity surface of the tire. As a result, the inventors found that the thickness of the rubber layer (rim cushion 24 and side tread 26) of the tire 10 is not excessively increased at the mounting position (tire radial position) of the power receiving coil 40, and the tire radial position of the power receiving coil 40 is not excessively close to the bead core 14 that may include a metal member, thereby further improving the power supply efficiency.

[0041] Specifically, by setting the above parameter (CH / SH) to be (-0.1r + 0.17) or more, the power receiving coil 40 will not approach the bead core 14 shown in FIG. 1 too much. Therefore, it is possible to suppress the magnetic field blocking by the bead core 14, and the rubber layer (rim cushion 24 and side tread 26) will not become excessively thick at the tire radial position where the power receiving coil 40 is mounted. As a result, more excellent power supply efficiency can be realized. It should be noted that the above parameter (CH / SH) is more preferably (-0.1r + 0.19) or more, and extremely preferably (-0.1r + 0.21) or more.

[0042] (Additional Form 3) In the basic form 1 or the form obtained by adding the additional form 2 to the basic form 1, the tire radial dimension DH from the outermost tire radial position of the power receiving coil 40 shown in FIG. 1 to the innermost tire radial position of the belt 20 (hereinafter, may be referred to as "dimension DH from the power receiving coil to the belt"), the tire radial region WH from the outermost tire radial position of the bead core 14 to the innermost tire radial position of the belt 20, and the sum of the products of the thickness Gi of the rubber layer disposed outside the tire width direction of the carcass 18 and the hardness Hi of this rubber layer on the line drawn in the tire width direction from the center position of the power receiving coil 40 in the tire radial direction, i.e., [ΣGiHi], satisfy the following relationship: 80≦(DH / WH)×[ΣGiHi] ≦800 It is preferable to satisfy this condition (Additional Form 3).

[0043] Here, as the rubber layer disposed on the outer side in the tire width direction of the carcass 18, the bead filler 16, the rim cushion 24, and the side tread 26 shown in FIG. 1 are included. In addition, this rubber layer further includes a second filler (not shown) that is located on the outer side in the tire width direction of the folded portion 18b of the carcass 18 and on the inner side in the tire width direction of the rim cushion 24 and the side tread 26.

[0044] Moreover, the total thickness of these rubber layers is preferably 4 mm or more in consideration of tire rigidity, and preferably 15 mm or less in consideration of power feeding efficiency. Also, the hardness of each rubber layer can be set to 50 degrees to 98 degrees (for example, measured by a durometer type A based on JIS-K6253).

[0045] The inventors have earnestly studied to further suppress the deformation that the power receiving coil 40 shown in FIG. 1 undergoes during tire rotation and further enhance the durability of the power receiving coil 40. As a result, the inventors have obtained the finding that it is important to further increase the rigidity of the tire 10 at the tire radial position of the tire inner cavity surface where the power receiving coil 40 shown in FIG. 1 is attached.

[0046] That is, the inventors determine the product of the tire width direction dimension Gi (i is an integer of 1 or more, the same hereinafter) and the hardness Hi of each rubber layer existing on the line drawn in the tire width direction from the tire radial center position at the tire radial position (for example, the tire radial center position of the power receiving coil 40) where the power receiving coil 40 is attached, and further add up the above products G1H1, G2H2, G3H3,... obtained for all rubber layers to calculate the sum ΣGiHi, and find that the minimum value of this sum is regarded as the tire rigidity at the attachment position of the power receiving coil 40.

[0047] However, the tire rigidity at the attachment position of the power receiving coil 40 is also affected by the relationship between the tire radial power receiving region WH shown in FIG. 1 and the region DH from the power receiving coil 40 to the belt 20. The reason is as follows.

[0048] Generally, the rigidity of a tire is higher near the bead core 14 shown in FIG. 1 due to the influence of the rubber thickness and rubber hardness, and tends to be lower at positions farther from the bead portion A in the region from the sidewall portion B to the shoulder portion C. Therefore, at the installation position of the power receiving coil 40 where the ratio DH / WH of the region DH to the region WH is small, it is necessary to increase the rubber thickness and rubber hardness to compensate for the rigidity. On the other hand, at the installation position of the power receiving coil 40 where the ratio DH / WH is large, since a certain degree of rigidity is already ensured, there is little need to increase the rubber thickness and rubber hardness to further increase the rigidity.

[0049] Based on the above findings, considering the ratio DH / WH as an adjustment parameter, the product obtained by multiplying the above sum ΣGiHi by this adjustment parameter, the ratio DH / WH, is finally regarded as the tire rigidity at the attachment position of the power receiving coil 40, and the minimum value thereof is obtained.

[0050] Specifically, by setting (DH / WH)×[ΣGiHi] to 80 or more, the tire rigidity at the attachment position of the power receiving coil 40 can be further increased, thereby further suppressing the deformation received by the power receiving coil 40 during tire rolling, and ultimately further improving the durability of the power receiving coil 40. It is more preferable that (DH / WH)×[ΣGiHi] is 100 or more, and extremely preferably 120 or more.

[0051] Next, the inventors of the present invention focused on the fact that the power receiving coil 40 shown in FIG. 1 generates heat during tire rolling, and intensively studied the suitable heat dissipation performance of the power receiving coil 40. As a result, through various experiments, the inventors obtained the finding that the heat dissipation performance of the power receiving coil 40 during tire rolling can be improved by setting an upper limit value for the above-mentioned (DH / WH)×[ΣGiHi].

[0052] Specifically, by setting (DH / WH)×[ΣGiHi] to 800 or less, heat generation by the power receiving coil 40 can be suppressed, and thus the heat dissipation performance can be improved. It is more preferable that (DH / WH)×[ΣGiHi] is 760 or less, and extremely preferably 720 or less.

[0053] (Additional form 4) In the basic form 1 or the form obtained by adding at least one of the additional forms 2 and 3 to the basic form 1, it is preferable that the folded end 18c of the carcass 18 shown in FIG. 1 is located on the outer side or the inner side in the tire radial direction of the tire radial region CW where the power receiving coil 40 is provided (Additional form 4).

[0054] Generally, the rigidity locally changes in the vicinity of the folded end 18c of the carcass 18. For this reason, stress concentration may occur between the folded end 18c and other rubber layers surrounding it during tire rolling. Installing the power receiving coil 40 near the folded end 18c where such stress concentration may occur is not preferable because the possibility of the power receiving coil 40 deforming during tire rolling increases.

[0055] Based on such findings, in the present embodiment, the folded end 18c of the carcass 18 shown in FIG. 1 is positioned on the outer side or the inner side in the tire radial direction of the tire radial region CW where the power receiving coil 40 is provided. Therefore, deformation of the power receiving coil 40 during tire rolling can be suppressed, and further, the durability of the power receiving coil 40 can be enhanced.

[0056] In the above-described additional form 4, considering the average tire thickness A in the tire radial region CW where the power receiving coil 40 shown in FIG. 1 is provided, the folded end 18c of the carcass 18 is located on the outer side or the inner side in the tire radial direction of the region Ca obtained by adding the same tire radial dimension A as the average tire thickness A to the upper and lower sides in the tire radial direction of the tire radial region CW (Additional form 4´). Here, the average tire thickness refers to the tire thickness at the intermediate position in the tire radial direction of the tire radial region CW.

[0057] As described above, in the present embodiment, the folded end 18c of the carcass 18 is positioned on the outer or inner side in the tire radial direction of the region Ca having the tire radial dimension A equal to the average tire thickness A on the upper and lower sides in the tire radial direction of the tire radial region CW. As a result, the power receiving coil 40 can be installed away from the boundary portion between the folded end 18c and the rubber layer surrounding the folded end 18c, where stress concentration occurs during tire rolling. As a result, it is possible to more reliably prevent the power receiving coil 40 from deforming during tire rolling, and thus the durability of the power receiving coil 40 can be realized at an extremely high level.

[0058] (Additional Form 5) FIG. 2 is a side view of the tire showing the state in which the tire 10 shown in FIG. 1 is assembled to a rim and a normal internal pressure is applied. (a) shows the non-grounded state (i.e., the no-load state), and (b) shows the grounded state (when a load of 80% of the normal load is applied). In FIG. 1, the tire radial dimension from the innermost position in the tire radial direction of the tire 10 to the outermost position in the tire radial direction of the power receiving coil is defined as CH.

[0059] In the basic form 1 or the form obtained by adding at least any one of the additional forms 2 to 4 to the basic form 1, the ratio Rc (CHD / CHI) of the tire radial dimension CHD (mm) from the innermost position in the tire radial direction to the outermost position in the tire radial direction of the power receiving coil in the region directly above the ground of the tire 10 at the grounded state (FIG. 2(b)) shown in FIG. 2 to the tire radial dimension CHI (mm) from the innermost position in the tire radial direction to the outermost position in the tire radial direction of the power receiving coil of the tire 10 at the non-grounded state (FIG. 2(a)), and the ratio Rs (SHD / SHI) of the tire cross-sectional height SHD (mm) in the region directly above the ground of the tire 10 at the grounded state (FIG. 2(b)) to the tire cross-sectional height SHI (mm) at the non-grounded state (FIG. 2(a)) satisfy 1.05 < Rc / Rs < 1.35 (Additional Form 5), which is preferable. Note that both the above tire radial dimensions CHD (mm) and CHI (mm) are dimensions related to the region indicated by the tire radial dimension CH shown in FIG. 1. Further, the region directly above the ground contact refers to the region included in a plane (which actually corresponds to the tire meridian cross-section) that includes the tire rotation axis and extends vertically from the tire rotation axis to the ground contact surface with respect to the ground contact surface.

[0060] The inventors further earnestly studied the requirement that when the tire 10 shown in FIG. 1 is mounted on a rim and a normal internal pressure is applied and a load of 80% of the normal load is applied, the deformation of the power receiving coil 40 becomes small with respect to the deflection in the tire radial direction.

[0061] Originally, when a load of 80% of the normal load is applied, as shown in FIG. 2, not only does the tire cross-sectional height SH (mm) (see FIG. 1) decrease, but also the tire radial dimension CH (mm) (the tire radial dimension from the innermost position in the tire radial direction of the tire 10 to the outermost position in the tire radial direction of the power receiving coil 40, see FIG. 1) decreases. Here, when the decrease in the tire radial dimension CH is significantly larger than the decrease in the tire cross-sectional height SH when a load of 80% of the normal load is applied, a sufficient tire radial region where the power receiving coil 40 can be mounted is not ensured, and there is a risk that the power receiving coil 40 will be deformed when the tire rolls.

[0062] Based on such findings, the inventors decided to set an upper limit value for the above parameter Rc / Rs as a result of various experiments. Specifically, by setting the above parameter Rc / Rs to less than 1.35, the decrease in the tire radial dimension CH does not become excessively large with respect to the decrease in the tire cross-sectional height SH, and thus a sufficient tire radial region where the power receiving coil 40 can be mounted is ensured (that is, in the case of a passenger car tire, the tire radial dimension is in the range of 20 mm to 55 mm). Therefore, the deformation of the power receiving coil 40 during tire rolling can be further suppressed. It is more preferable that the above parameter Rc / Rs is 1.33 or less, and extremely preferably 1.30 or less.

[0063] Incidentally, as a result of conducting numerous experiments using various tire sizes, the inventors have reached the conclusion that it is almost impossible for the parameter Rc / Rs to be 1.05 or less, and thus have set the parameter Rc / Rs to be greater than 1.05.

[0064] <Wireless power supply system> [Basic form 6] FIG. 3 is a diagram showing a wireless power supply system 50 according to the present embodiment, including a power transmission coil 52 and a tire 10 provided with a power reception coil 40 (on one side in the tire width direction with respect to the tire equatorial plane CP in a tire meridian cross-sectional view). In the figure, the tire portion on the side opposite to the ground contact surface is shown in a state where the tire is assembled with a rim and a normal internal pressure is applied, and a load of 80% of the normal load is applied (hereinafter, the same applies to the invention of the wireless power supply system). The power transmission coil 52 shown in the figure is a coil wound around the tire width direction. In particular, for the portion extending in the tire diameter direction, it may extend only in the tire diameter direction, or may also extend in at least one of the tire circumferential direction and the tire width direction in addition to the tire diameter direction.

[0065] The power transmission coil 52 shown in the figure forms a resonance circuit with a capacitor and a coil, and is attached to the surface on the tire side of a knuckle or a hub carrier, which is a component of a vehicle's steering axle (not shown), or any component constituting a strut structure. The position where the power transmission coil 52 is installed will be described in detail below.

[0066] The power transmission coil 52 is preferably installed on a vehicle's lower spring member. The lower spring member includes, for example, a knuckle, a brake caliper, and a damper case of a strut suspension. By providing the power transmission coil 52 on the lower spring member, even when the vehicle moves up and down due to road surface irregularities, the distance between the power transmission coil 52 and the power reception coil 40 provided on the tire 10 can be kept constant.

[0067] In the wireless power supply system 50 shown in FIG. 3, the power transmission coil 52 can be provided in a damper case of a strut suspension (not shown). For example, the power transmission coil 52 may be provided in the damper case of the front wheel, or may be provided in the damper case of the rear wheel. Thereby, even when the tire 10 moves up and down due to unevenness of the road surface, the power transmission coil 52 faces the power reception coil 40 in the tire width direction, avoids the belt and the bead core, and can transmit power in the tire width direction. Therefore, the wireless power supply system 50 can improve the power supply efficiency.

[0068] Further, the power transmission coil 52 may be provided on a member that moves together with the tire 10 in conjunction with steering, such as a knuckle (not shown) of a multi-link type suspension. Thereby, even during steering, the distance between the power transmission coil 52 and the power reception coil 40 provided on the tire 10 can be kept constant. Therefore, the tire 10 can be stably powered during traveling.

[0069] Next, the power reception coil 40 shown in FIG. 3 has the same configuration as the power reception coil 40 shown in FIG. 1, and constitutes a resonance circuit by a capacitor and a coil. The tire 10 shown in FIG. 3 is a tire of the basic form 1 regarding the tire 10 described above and at least one of the additional forms 2 to 5 added to the basic form 1, and its actions, functions, etc. are as described above.

[0070] Under such a premise, the wireless power supply system 50 according to the present embodiment is a wireless power supply of a magnetic field resonance method using an alternating magnetic field. As shown in FIG. 3, power is supplied to the power transmission coil 52, and power is transmitted to the power reception coil 40 by electromagnetic induction. According to such a wireless power supply system 50, as described above, the power supply efficiency can be improved.

[0071] Here, in order to drive sensors and associated electric circuits installed in the tire 10, it is preferable to transmit power of 0.1 to 15 W at a frequency of 1 to 20 MHz.

[0072] Also, the shortest distance between the power transmission coil 52 and the power reception coil 40 (hereinafter, may be referred to as "transmission gap G") is preferably 10 mm or more and 80 mm or less. Here, the transmission gap G is a value measured in a state where the tire 10 is mounted on the rim, normal internal pressure is applied, and the vehicle is mounted and stopped on a flat ground. Further, in FIG. 3, the transmission gap G is the shortest distance between the power transmission coil 52 and the power reception coil 40, that is, in FIG. 3, the distance between the innermost position in the tire width direction of the power transmission coil 52 and the outermost position in the tire width direction of the power reception coil 40.

[0073] By setting the transmission gap G to 10 mm or more, it is possible to suppress the excessive change rate of the received power caused by the variation in the relative position between the power transmission coil 52 and the power reception coil 40 shown in FIG. 3 in the power transmission direction, and the circuit configuration connected to the power reception coil 40 can be made simple, and thus stable power can be easily supplied to the electronic device. Here, the variation in the received power depends on the fact that during the rolling of the tire 10, the tire 10 expands slightly due to centrifugal force, and the relative position between the two coils 52 and 40 varies. Specifically, the higher the tire rolling speed, the more the tire 10 expands in the tire radial direction, and the power reception coil 40 moves to the outer side in the tire radial direction (upper side in FIG. 3), while the position of the power transmission coil 52 remains unchanged, so the relative position between the two coils 52 and 40 changes.

[0074] On the other hand, by setting the transmission gap G to 80 mm or less, the magnetic field strength generated between the two coils 52 and 40 does not become excessively small, and power feeding by electromagnetic induction can be efficiently performed.

[0075] Note that the transmission gap G is more preferably 12 mm or more and 75 mm or less, and extremely preferably 15 mm or more and 70 mm or less.

[0076] By adopting the range of the transmission gap G, the power range, and the frequency band as described above, not only can the temperature rise of the power receiving coil 40 be suppressed, but also an increase in the number of turns of the coil (and thus an increase in the coil weight) is not required, so that the rolling resistance of the tire is not increased, power feeding can be efficiently performed, and excellent transmission efficiency can be realized. In particular, according to the range of the transmission gap G described above, excellent power feeding efficiency can be obtained when power is transmitted using the tire structure in the wireless power feeding of the magnetic field resonance method in the above frequency band.

[0077] [Additional Form 7] FIG. 4 is a diagram showing that at least a part of the power receiving coil 40 is located within the power feeding region of the power transmitting coil 52 for the wireless power feeding system 50 according to the present embodiment. (A) and (B) show examples in which the power feeding direction is the tire width direction, and (C) and (D) show examples in which the power feeding direction is inclined with respect to the tire width direction. In FIG. 4, (A) and (C) are examples in which the radially inner portion of the tire of the power receiving coil 40 is included in the power feeding region of the power transmitting coil 52, and (B) and (D) are examples in which the radially outer portion of the tire of the power receiving coil 40 is included in the power feeding region of the power transmitting coil 52.

[0078] In the basic form 6, as shown in FIGS. 4(A) to 4(D), in the tire meridian cross-sectional view, it is preferable that at least a part of the power receiving coil 40 is located within the power feeding region extending in the winding axis direction of the power transmitting coil 52 between both longitudinal ends of the power transmitting coil 52 (Additional Form 7). Here, the positional relationship between the power receiving coil 40 and the power transmitting coil 52 is measured in a state where the tire 10 is rim-mounted, a normal internal pressure is applied, and the vehicle is attached and stopped on a flat ground.

[0079] In the wireless power supply system 50 according to the present embodiment, the power transmission coil 52 is attached to a knuckle or a hub carrier that is a component of the steering axle of the vehicle (located on the outer side in the tire width direction of the sidewall portion B), or to the tire-side surface of any component constituting the strut structure. For this reason, when considering the power supply efficiency in view of the shape of the tire 10, particularly the sidewall portion B, as shown in FIGS. 4(A) and 4(B), it is desirable that the direction of the magnetic field lines penetrating the tire in the sidewall portion B, and thus the power supply direction Dp, be substantially in the tire width direction.

[0080] In accordance with such findings, as shown in FIGS. 4(A) and 4(B), when the power supply direction Dp is substantially in the tire width direction, as in the present embodiment, power supply can be performed more efficiently, and thus excellent transmission efficiency can be achieved.

[0081] Also, in the examples shown in FIGS. 4(B) and 4(C), for each of the power transmission coil 52 and the power reception coil 40, the component surfaces (the planes perpendicular to the winding axes of the respective coils in FIGS. 4(B) and 4(C)) are parallel to each other. Therefore, compared with the examples shown in FIGS. 4(A) and 4(D), power supply can be performed more efficiently, and thus excellent transmission efficiency can be achieved.

[0082] Note that, as shown in FIGS. 4(A) and 4(D), the power transmission coil 52 and the power reception coil 40 do not necessarily have their component surfaces parallel to each other. The reason is that an electromotive force is generated by electromagnetic induction if the magnetic field generated by the power transmission coil 52 links with the power reception coil 40, and there is no constraint on the relative orientation of the above-mentioned surfaces.

[0083] [Additional Form 8] FIG. 5 is a diagram showing the installation position of the power transmission coil 52 for the wireless power supply system 50 according to the present embodiment.

[0084] In the basic form 6 or the form obtained by adding the additional form 7 to the basic form 6, as shown in FIG. 5, it is preferable that the power transmission coil 52 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 O (additional form 8).

[0085] Normally, when the tire 10 rolls, while the power receiving coil 40 deforms along with the deformation at the grounding portion of the tire 10, almost no deformation of the power receiving coil 40 due to tire deformation is observed at the portion away from the grounding portion of the tire 10 (the upper portion of the tire 10 in FIG. 5). For this reason, by installing the power transmission coil 52 arranged outside the tire 10 near the upper part of the tire away from the installation portion of the tire 10 (range R of 60° on both sides in the tire circumferential direction centered on an imaginary line extending vertically upward from the tire center O), during tire rolling, the variation of the above-described transmission gap G can be suppressed, power supply can be performed more efficiently, and thus more excellent transmission efficiency can be realized. Note that the example shown in FIG. 5 is an example of attaching the power transmission coil 52 to the wheel house 54, and the above-described range R is applied within the wheel house 54.

[0086] It is more preferable that the power transmission coil 52 is installed within a range of 55° on both sides in the tire circumferential direction centered on the above-described imaginary line, and it is extremely preferable that the power transmission coil 52 is installed within a range of 50° on both sides in the tire circumferential direction centered on the above-described imaginary line.

[0087] Also, the shape of the power transmission coil 52 is not particularly limited, but when the power transmission coil 52 is installed in, for example, the wheel house, it is preferable to use a so-called spiral coil that can reduce the thickness as a whole.

[0088] <Other forms of the tire and the wireless power supply system> The above is the description of the tire and the wireless power supply system according to the present invention. Hereinafter, other matters regarding the tire and the wireless power supply system according to the present invention will be listed.

[0089] The carbon content of the inner liner 12, which is a component of the tire 10 shown in FIG. 1, is 45 to 75 parts by mass (parts by mass when the rubber is 100, the same hereinafter), the carbon content of the side tread is 25 to 65 parts by mass, the carbon content of the rim cushion is 60 to 90 parts by mass, the carbon content of the bead filler 16 is 40 to 80 parts by mass, the carbon content of the covering rubber of the carcass 18 is 35 to 70 parts by mass, and the carbon content of the run-flat liner is preferably 45 to 75 parts by mass. By adopting these respective compounding amounts, it is possible to realize the desired physical properties (such as hardness and elastic modulus) and heat dissipation properties in each rubber layer, while realizing the excellent power feeding efficiency described above. Usually, it is most preferable to adjust the carbon content for the heat dissipation property of the rubber because it is effective and it is easy to balance with the properties of the rubber required for the tire.

[0090] Regarding the wireless power feeding system 50 shown in FIG. 3, it is preferable that the power receiving coil 40 is provided on the inner cavity surface of the sidewall portion B of the tire 10 so that the configuration surface faces in the tire width direction. As described above, as shown in FIGS. 4(A) and (B), when the power feeding direction by the power transmitting coil 52 is in the substantially tire width direction, by providing the power receiving coil 40 so that its configuration surface faces in the tire width direction, the power transmitting surface of the power transmitting coil 52 and the configuration surface of the power receiving coil 40 become parallel. Thereby, power feeding can be performed more efficiently, and thus excellent transmission efficiency can be realized.

[0091] FIG. 6 is a view showing an arrangement mode of the power receiving coil 40 (a mode in which the power receiving coil 40 is not continuous in the tire circumferential direction, different from the case of FIG. 2), and (A) to (F) are examples showing the power receiving coil 40 composed of 2 sets, 3 sets, 4 sets, 5 sets, 6 sets, and 8 sets of power receiving coil elements 40a respectively, (G) is an example in which a plurality of power receiving coil elements 40a are laminated in the tire radial direction, and (H) is an example in which a part of a plurality of power receiving coil elements 40a extends obliquely with respect to the tire radial direction.

[0092] As shown in FIGS. 6(A) to 6(H), the power receiving coil 40 may be formed from a plurality of power receiving coil elements 40a. On the inner surface of the tire cavity where the power receiving coil 40 is provided, during the rolling of the tire 10, the deformation and release of the tire 10 are repeated. When one power receiving coil 40 is provided around the entire circumference of the tire 10, this power receiving coil 40 has a portion that is distorted under deformation (near the grounding portion of the tire 10) and a portion that is not deformed (the upper portion of the tire 10) during the rolling of the tire 10, and the power receiving coil 40 is likely to peel off from the inner surface of the tire cavity. Therefore, by dividing the tire circumference into a plurality of regions and arranging the power receiving coil elements 40a in each of the divided regions, it is possible to suppress the peeling of the power receiving coil 40 from the inner peripheral surface of the tire.

[0093] FIG. 7 is a tire meridian cross-sectional view (however, half in the tire width direction) showing a power supply mode for supplying power from the power receiving coil 40 to an electronic device 46 attached to the inner surface of the tire cavity via a power line 44 in the tire 10 shown in FIG. 1.

[0094] According to what is shown in the figure, the power receiving coil 40 is connected to a capacitor (not shown) as a resonant circuit, and further, via a power line 44 attached to the inner surface of the tire cavity, power can be supplied to an electronic device 46 (sensor, signal processing circuit, communication corridor, etc.) attached to the inner surface of the tire cavity. The electronic device 46 has lower durability against deformation than the power receiving coil 40, and on the other hand, even if it is installed near the belt 20 which is a magnetic body, no trouble occurs due to the influence of the magnetic field. For this reason, the electronic device 46 is arranged on the inner surface of the tire cavity in the tire width direction region where the belt 20 having high rigidity in the tire 10 is formed, the power receiving coil 40 is arranged on the inner surface of the tire cavity in the sidewall portion B where the power supply efficiency can be increased, and the two are wired-connected by the power line 44. Thereby, the power received by the power receiving coil 40 can be supplied to the electronic device 46 with less loss and high power supply efficiency, and at the same time, the durability of the electronic device 46 can be ensured. Further, by arranging all these components (power receiving coil 40, capacitor, power line 44, and electronic device 46) on the inner surface of the tire cavity, an increase in the manufacturing cost and manufacturing difficulty of the tire 10 is suppressed.

Example

[0095] The following describes the comparison of the predetermined effects of the present application among the inventions defined in claims 1 to 5 of the present application (hereinafter referred to as "Invention Examples 1 to 5"). Regarding the comparison between Invention Examples 1 to 5 and the conventional example (the example described in Patent Document 1), as described above, since the difference in the predetermined effects of the present application is obvious in terms of the configuration, it is not particularly described together.

[0096] The tire size was set to 245 / 40R19 (specified by JATMA), and a wireless power supply system 50 (Invention Examples 1 to 5 and Reference Example) shown in FIG. 3 was manufactured, and the power supply efficiency from the power transmission coil 52 to the power reception coil 40 was investigated. Regarding the various conditions of the tire 10 included in each of the wireless power supply systems 50 of Invention Examples 1 to 5 and the Reference Example, they are as shown in Table 1 below.

[0097]

Table 1

[0098] Regarding the wireless power supply systems of Invention Examples 1 to 5 manufactured in this way, the ratio (power transmission efficiency) of the power 2 received by the power reception coil (and the resonance circuit of the capacitor) to the power 1 transmitted from the power transmission coil 52 was measured and expressed as an index when Invention Example 1 was set to 100. The measurement of the ratio of the above powers 1 and 2 was performed using a vector network analyzer. The results are also shown in Table 1. In this specification, it is assumed that the ratio of the transmitted power (power transmission efficiency) is good at 95 or more.

[0099] According to Table 1, it can be seen that all the wireless power supply systems belonging to the technical scope of the present invention show excellent power transmission efficiency and thus achieve excellent power supply efficiency.

Explanation of Signs

[0100] 10 Tire 12 Inner liner 14 Bead core 16 Bead filler 18 Carcass 18a Body part 18b Folded-back part 18c Folded-back end 20 Belt 20a, 20b Belt layers 22 Belt cover 22a, 22b, 22c Belt cover layers 24 Rim cushion 26 Side tread 28 Wing tip 30 Cap tread 40 Power receiving coil 41, 41a, 41b Fixing members 42 Wire 44 Power line 46 Electronic device 50 Wireless power supply system 52 Conductive coil 54 Wheelhouse A Bead part B Sidewall part C Shoulder part D Tread part Dp Power supply direction G Transmission gap O Tire center P1 The outermost position in the tire radial direction of the bead core 14 P2 The innermost position in the tire radial direction of the belt 20 R The tire circumferential direction range of 60° on both sides of the virtual line extending vertically upward from the tire center O

Claims

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

2. The relationship among the tire radial dimension CH (mm) from the innermost position in the tire radial direction of the tire to the outermost position in the tire radial direction of the power receiving coil, the tire cross-sectional height SH (mm), and the flatness ratio r (0 < r ≦ 1) of the tire is −0.1r + 0.17 ≦ CH / SH ≦ −0.3r + 0.6 The tire according to claim 1, which satisfies this.

3. The relationship among the tire radial dimension DH from the outermost position in the tire radial direction of the power receiving coil to the innermost position in the tire radial direction of the belt, the tire radial region WH, and the sum [ΣGiHi] of the product of the thickness Gi and the hardness Hi of the rubber layer disposed on the outer side in the tire width direction of the carcass on a line drawn in the tire width direction from the center position in the tire radial direction of the power receiving coil is 80 ≦ (DH / WH) × [ΣGiHi] ≦ 800 The tire according to claim 1 or 2, which satisfies this.

4. The tire according to claim 1 or 2, wherein the folded end of the carcass is located outside or inside in the tire radial direction of the tire radial region CW where the power receiving coil is provided.

5. The ratio Rc (CHD / CHI) of the tire radial dimension CHD (mm) from the innermost position in the tire radial direction in the region directly above the ground of the tire when grounded to the outermost position in the tire radial direction of the power receiving coil to the tire radial dimension CHI (mm) from the innermost position in the tire radial direction of the tire to the outermost position in the tire radial direction of the power receiving coil when not grounded, and the ratio Rs (SHD / SHI) of the tire cross-sectional height SHD (mm) in the region directly above the ground of the tire when grounded to the tire cross-sectional height SHI (mm) when not grounded, and the ratio Rc / Rs of these satisfy 1.05 < Rc / Rs < 1.35 The tire according to claim 1 or 2, which satisfies this.

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

7. The wireless power supply system according to claim 6, wherein 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 transmission coil between both longitudinal ends of the power transmission coil in a tire meridian cross-sectional view.

8. The wireless power supply system according to claim 6 or 7, 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 tire center.

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