Tire and wireless power supply system

Abstract

To provide a tire and a wireless power supply system using the tire, which are unlikely to interfere a magnetic field reaching a power receiving coil from a power transmission coil and enable suppressing reduction in power supply efficiency.SOLUTION: A tire comprises: a tread part having a tread surface; a pair of bead parts; a pair of side wall parts provided between the tread part and the bead parts; a reinforcement layer having a steel cord; and a power receiving coil for receiving electric power supplied from outside the tire via an alternating magnetic field. In a front view, the ratio of the area of a portion other than the steel cord to the area of the reinforcement layer is 0.1 or more and 0.7 or less.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, a wireless power reception system has been disclosed in which power is supplied 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, it is disclosed that a steel cord can be used for the belt constituting the tire (

[0022] ). However, when a steel cord is used for the belt, a part of the magnetic field that should reach the power reception coil from the power transmission coil may be blocked by the belt, and thus excellent power supply efficiency may not be achieved.

[0005] An object of the present invention is to provide a tire that hardly hinders the magnetic field reaching from the power transmission coil to the power reception coil and can suppress a decrease in power supply efficiency, and a wireless power supply system using the tire.

Means for Solving the Problems

[0006] The tire of the present invention includes a tread portion having a tread surface, a pair of bead portions, a pair of sidewall portions provided between the tread portion and the bead portions, a reinforcing layer having steel cords, and a power receiving coil that receives power supplied by an alternating magnetic field from the outside of the tire. In the reinforcing layer, the area ratio of the portion other than the steel cords to the area of the reinforcing layer in a front view is 0.1 or more and 0.7 or less.

Effect of the Invention

[0007] According to the present invention, it is difficult to obstruct the magnetic field reaching the power receiving coil from the power transmission coil, and a decrease in power supply efficiency can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 14

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Figure 18

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Figure 20

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the tire according to the present invention (Basic Form 1 and Additional Forms 2 to 13 shown below), and embodiments of the wireless power supply system according to the present invention (Basic Form 14 and Additional Forms 15, 16 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. Also, the tire circumferential direction refers to the circumferential 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 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.

[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 normal 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 "INFLATION PRESSURES" defined by ETRTO. The normal 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 "LOAD CAPACITY" defined by ETRTO.

[0013] <Tire> [Basic Form 1] The basic form of the tire according to the embodiment of the present invention will be described below. FIG. 1 is a meridian cross-sectional view of the tire according to the present embodiment. In the figure, the tire part on the side opposite to the ground contact surface is shown in a state where the normal internal pressure is applied with the rim assembled and a load of 80% of the normal load is applied (hereinafter, the same applies to the invention of the tire).

[0014] As shown in FIG. 1, the 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. An inner liner 12 exposed on the inner cavity surface of the tire is provided in the region from the bead portion A to the tread portion D. 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) are sequentially provided on the outer side in the tire radial direction.

[0015] Further, outside the folded 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 and a cap tread 30 are provided in sequence.

[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 tire inner cavity surface. The inner liner 12 can be composed of a single inner liner layer, or can also be composed of 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 layer with low air permeability, and as other layers, it can include an adhesive layer at least at 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 increasing the rigidity of the bead portion A, and the tire width direction dimension at the inner end portion in the tire radial direction thereof is substantially equal to the tire width direction dimension at the outer end portion in the tire radial direction 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 outer side in the tire radial 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, 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 the tire inner cavity surface of the inner liner 12 substantially perpendicularly 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, resin fibers such as rayon, polyester, polyamide, and aramid can be used.

[0019] The belt 20 is a reinforcing layer provided on the outer side of the carcass 18 in the tire radial direction. It is a member that tightens the carcass 18 to increase 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 composed of a plurality of belt layers (two belt layers 20a and 20b in the example shown in FIG. 1) laminated in the tire radial direction in the tread portion D. Each of the belt layers 20a and 20b has a structure in which a plurality of steel cords are coated with rubber.

[0020] The belt cover 22 is a member that reinforces the tightening effect of the carcass 18 by the belt 20, and is a member for preventing the tread portion D from deforming due to the centrifugal force generated particularly during high-speed running of the vehicle. The belt cover 22 can be composed of a plurality of belt cover layers (two belt cover layers 22a and 22b in the example shown in FIG. 1) laminated in the tire radial direction on the outer side of the belt 20 in the tire radial direction. Each of the belt cover layers 22a and 22b has a structure in which a plurality of cords are coated with rubber. Generally, organic fiber cords are used as the cords for the belt cover layer. The tire 10 includes a second carcass 29 inside the carcass 18. The second carcass 29 includes a main body portion 29a extending along the inner liner 12, and a folded-back portion 29b folded back around the bead core 14 and the bead filler 16. Further, a steel reinforcement 33 as a reinforcing layer is provided between the folded-back portion 29b and the bead filler 16. By providing the steel reinforcement 33, the rigidity of the sidewall portion B can be appropriately improved. The steel reinforcement 33 has a structure in which a plurality of steel cords are coated with rubber.

[0021] The rim cushion 24 is provided in a region that contacts the rim flange 8 of the rim 6, and the side tread 26 is arranged so as to connect the rim cushion 24 and the tread portion D. The cap tread 30 is formed on the tread surface 34 that is the surface of the tread portion D. A plurality of circumferential main grooves 36 are provided in the tread surface 34. With a pair of outer circumferential main grooves 38 arranged on the outermost side in the tire width direction as a boundary, a center land portion 35 is demarcated and formed inside the outer circumferential main groove 38 in the tire width direction, and shoulder land portions 37 are demarcated and formed outside the outer circumferential main groove 38 in the tire width direction, respectively. Note that for the rim cushion 24, the side tread 26, and the cap tread 30, 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 38 of the tire 10 shown above, 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, for example, on the inner cavity surface of the tire. 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, but in particular, a rubber having a relatively high thermal conductivity such as silicone rubber can be used for the fixing portion) (FIG. 1).

[0023] Power supply using the tire 10 according to the present embodiment converts a DC current obtained from an in-vehicle battery (not shown) into an AC current once by an AC power supply device, and applies this AC current to a power transmission coil (for example, attached to the tire-side surface of a knuckle which is a component of a vehicle's steering axle). By doing so, an AC magnetic field is generated 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] As shown in FIG. 2, the reinforcing layer 11 of the tire 10 according to this embodiment has an area ratio of the portion excluding the steel cord to the area of the reinforcing layer 11 in a front view of 0.1 or more and 0.7 or less.

[0025] As described above, the reinforcing layer 11 is the belt 20 or the steel reinforcement 33. In the following description, when the belt 20 and the steel reinforcement 33 are not distinguished, they will be collectively described as the reinforcing layer 11. The reinforcing layer 11 is formed of a plurality of steel cords. The steel cord includes a case of a single wire composed of a single filament and a case of a stranded wire composed of a plurality of filaments. The reinforcing layer 11 shown in FIG. 2 is in a state of being stacked two sheets in a direction orthogonal to the surface direction in a front view, that is, in the thickness direction. In a state where the reinforcing layer 11 is stacked in the thickness direction, the steel cords 13 are arranged in a lattice pattern. The two stacked reinforcing layers 11 shown in FIG. 2 are applied to the belt 20. The reinforcing layer 11 is not limited to the case of being used in a stacked state of two sheets, and may be used as one sheet. One reinforcing layer 11 is applied to the steel reinforcement 33.

[0026] Of the stacked reinforcing layers 11, the steel cords 13 of one of the reinforcing layers 11 are inclined at a certain angle toward one side on the left and right from top to bottom with respect to the vertical direction of the paper surface of FIG. 2 and are arranged at a predetermined interval. Of the stacked reinforcing layers 11, the steel cords 13 of the other reinforcing layer 11 are inclined at a certain angle toward the other side on the left and right from top to bottom with respect to the vertical direction of the paper surface of FIG. 2 and are arranged at a predetermined interval. Each reinforcing layer 11 is covered with rubber for the steel cords 13 arranged as described above and is stacked. Since the steel cords 13 of the reinforcing layer 11 are covered with rubber, the steel cords 13 cannot be visually recognized or are difficult to visually recognize from the outside.

[0027] When each reinforcing layer 11 is stacked in the plane direction, the rubber portion 15 between the steel cords 13 becomes a rhombus shape when viewed from the thickness direction. That is, the two reinforcing layers 11 stacked in the thickness direction are classified into the portion of the steel cord 13 and the rubber portion 15 between the steel cords 13 when viewed from the thickness direction. When the surface area of the entire reinforcing layer is S and the surface area of the rubber portion 15 between the steel cords 13 is SR, the ratio of the area SR of the portion other than the steel cord 13 to the area S of the reinforcing layer (area ratio: SR / S) is 0.1 or more and 0.7 or less, preferably 0.15 or more and 0.65 or less, more preferably 0.2 or more and 0.6 or less.

[0028] The above area ratio can be measured as follows. First, a 25 mm × 25 mm reinforcing layer is cut out from the target tire to make a sample. At this time, avoid the splice portion where the reinforcing layers overlap in the thickness direction. Next, take an X-ray photograph of the sample in the thickness direction. The taken photograph is binarized, and the area of the transmission region (white portion) in an arbitrary region of 10 mm × 10 mm is taken as SR (the surface area of the rubber portion), and the area 100 mm of the arbitrary region 2 is taken as S (the surface area of the entire reinforcing layer), the value of SR / S is calculated, and the obtained value is taken as the area ratio.

[0029] (Function) When an alternating current is supplied to the power transmission coil provided outside the tire, a magnetic field having a specific frequency is generated. The magnetic field generated by the power transmission coil passes between the steel cords 13 of the reinforcing layer 11 from the outer surface of the tire and reaches the power reception coil 40. Due to the magnetic field, an electric current flows through the power reception coil 40 to generate electric power. The reinforcing layer 11 suppresses the steel cord 13 from blocking the magnetic field while exhibiting the effect of reinforcing the structure of the tire because the above area ratio (SR / S) is 0.1 or more and 0.7 or less. Therefore, the tire 10 can suppress a decrease in power supply efficiency.

[0030] When the above area ratio (SR / S) is less than 0.1, the area of the rubber portion 15 is too small, so the magnetic field reaching the reinforcing layer 11 may be blocked by the steel cord 13, and the power feeding efficiency may decrease. On the other hand, when the above area ratio (SR / S) exceeds 0.7, the proportion of the steel cord 13 is too small, so the effect of reinforcing the structure of the tire 10 may be reduced. In the above basic form 1, the reinforcing layer 11 has been described as being two layers stacked, but the present invention is not limited to this. The reinforcing layer 11 may be one layer or three or more layers.

[0031] [Additional form 2] In the basic form 1, the reinforcing layer 11 is the belt 20 provided in the tread portion D, and it is preferable that the area ratio (SR / S) of the portion excluding the steel cord 13 to the area of the belt 20 in a front view is 0.1 or more and 0.5 or less (Additional form 2), and more preferably 0.15 or more and 0.45 or less.

[0032] The tire 10 is provided with a power receiving coil 40 at a position where it is likely to receive the magnetic field generated by the power transmission coil provided on the outer side in the tire radial direction. The power receiving coil 40 may be provided at the position 40A on the inner surface of the tire on the side opposite to the tread surface 34 (hereinafter also referred to as the "inner surface of the tread portion"). The power receiving coil 40 provided at the position 40A may be wound with a conductor in a cylindrical shape centered on the tire rotation axis so that the conductors are aligned in the tire width direction along the inner surface of the tread portion. The power transmission coil provided on the outer side in the tire radial direction generates a magnetic field when alternating current power is supplied. The magnetic field generated by the power transmission coil passes between the steel cords 13 of the belt 20 from the outer side in the tire radial direction and reaches the power receiving coil 40 provided at the position 40A. Due to the magnetic field, an electric current flows through the power receiving coil 40 to generate electric power.

[0033] The belt 20 is a reinforcing layer 11 including a steel cord 13. By having the above area ratio (SR / S) within the above range, the rigidity of the tread portion of the tire 10 is increased, and while preventing separation between the carcass 18 and the cap tread 30, it suppresses the steel cord 13 from blocking the magnetic field. Therefore, the tire 10 can more reliably suppress a decrease in power feeding efficiency.

[0034] Incidentally, the power receiving coil 40 may be provided at the position 40C in FIG. 3. The power receiving coil 40 provided at the position 40C may have a conductor wound in a spiral shape centered on the tire rotation axis so that the conductors are aligned in the tire radial direction.

[0035] [Additional Form 3] In Basic Form 1, the reinforcing layer 11 is provided in the sidewall portion B, and it is preferable that the area ratio (SR / S) of the area of the portion excluding the steel cord 13 to the area of the reinforcing layer 11 in a front view is 0.3 or more and 0.7 or less (Additional Form 3), and more preferably 0.35 or more and 0.65 or less.

[0036] In Additional Form 3, more precisely, the reinforcing layer 11 is provided in the tire radial region from the end of the belt in the tire width direction to the outermost position of the bead core 14 in the tire radial direction. The reinforcing layer 11 according to Additional Form 3 is a steel reinforcement 33 provided in the above region. Also, the tire 10 includes a carcass layer in the sidewall portion B. The area of the reinforcing layer 11 in a front view is the surface area of the reinforcing layer 11, and is the area of the surface as viewed from a direction orthogonal to the plane including the steel cord included in the reinforcing layer 11. It is preferable that the steel reinforcement 33 has the above area ratio (SR / S) within the above range.

[0037] The power receiving coil 40 is provided at a position where it is likely to receive the magnetic field generated by the power transmission coil provided on the outer side in the tire width direction. The power receiving coil 40 may be provided at a position 40B on the inner surface of the tire on the side opposite to the tire side surface (FIG. 1). The power transmission coil provided on the outer side in the tire width direction generates a magnetic field when an alternating voltage is supplied. The magnetic field generated by the power transmission coil passes between the steel cords 13 of the sidewall portion B from the outer side in the tire width direction and reaches the power receiving coil 40 provided at the position 40B. Due to the magnetic field, an electric current flows through the power receiving coil 40, generating electric power.

[0038] The steel rainforces 33 are each a reinforcing layer 11. By the area ratio (SR / S) being within the above range, while moderately improving the rigidity of the sidewall portion B, it is possible to suppress the steel cord 13 from blocking the magnetic field. Therefore, the tire 10 can more reliably suppress a decrease in power feeding efficiency.

[0039] [Additional Form 4] In the basic form 1 or the form obtained by adding the additional form 2 or 3 to the basic form 1, the interval WG between adjacent steel cords 13 included in the reinforcing layer 11 is preferably 0.4 mm or more and 2.4 mm or less (additional form 4), and more preferably 0.5 mm or more and 2.2 mm or less.

[0040] As shown in FIG. 2, the interval WG between adjacent steel cords 13 is the distance between the opposing surfaces of the steel cords 13 in the reinforcing layer 11. By the interval WG between adjacent steel cords 13 being 0.4 mm or more, the reinforcing layer 11 can more reliably suppress blocking the magnetic field. By the interval WG between adjacent steel cords 13 being 2.4 mm or less, the reinforcing layer 11 can more reliably reinforce the tire structure. Therefore, the tire 10 can suppress a decrease in power feeding efficiency even when the reinforcing layer 11 exists between the power transmission coil and the power receiving coil 40.

[0041] The distance WG between the steel cords 13 is the measured value of the distance between the steel cords 13 closest to the power receiving coil 40. For example, when the reinforcing layer 11 is the belt 20 and two reinforcing layers 11 are stacked, the distance between the steel cords 13 of the reinforcing layer 11 on the inner side in the tire radial direction and closest to the power receiving coil 40 is measured. The distance between the steel cords 13 is measured by disassembling the target tire.

[0042] [Additional Form 5] In the basic form 1 or the form in which any one of the additional forms 2 to 4 is added to the basic form 1, it is preferable that the cross-sectional perimeter perpendicular to the longitudinal direction of the steel cord 13 is 1.5 mm or more and 7.0 mm or less (Additional Form 5), and more preferably 1.8 mm or more and 7.0 mm or less.

[0043] When the steel cord 13 is a single wire composed of one filament, the cross-sectional perimeter perpendicular to the longitudinal direction of the steel cord 13 is the perimeter of the cross-section perpendicular to the longitudinal direction of one filament. When the steel cord 13 is a stranded wire composed of a plurality of filaments, the cross-sectional perimeter perpendicular to the longitudinal direction of the steel cord 13 is the sum of the perimeters of the cross-sections perpendicular to the longitudinal directions of the respective filaments. The steel cord 13 is preferably a stranded wire composed of a plurality of filaments, and the cross-sectional area of the cross-section perpendicular to the longitudinal direction is 0.1 mm 2 or more and 0.7 mm 2 or less, preferably 0.12 mm 2 or more and 0.65 mm 2 or less is more preferable.

[0044] The steel cord 13 in the reinforcing layer 11 generates eddy currents in the steel cord 13 by receiving a magnetic field, and thereby generates heat.

[0045] The tire 10 has a predetermined contact area with the rubber covering the steel cord 13 by having a cross-sectional circumference orthogonal to the longitudinal direction of the steel cord 13 within the above range. Thereby, heat is efficiently dissipated from the steel cord 13 to the rubber. If the cross-sectional circumference is too small, there is a risk that heat cannot be dissipated sufficiently. If it is too large, the thickness of the reinforcing layer may become excessive, increasing the rolling resistance of the tire and the mass of the tire.

[0046] [Additional Form 6] In the basic form 1 or the form in which any one of the additional forms 2 to 5 is added to the basic form 1, it is preferable that the steel cord 13 is composed of 1 or more and 6 or less filaments (Additional Form 6).

[0047] The filament preferably has a diameter of 0.15 mm or more and 0.5 mm or less, and more preferably 0.2 mm or more and 0.4 mm or less. The steel cord 13 preferably consists of 6 or less filaments, and more preferably consists of 3 filaments (Fig. 4(A)), 4 filaments (Fig. 4(B)), or 6 filaments (Fig. 4(C) and (D)) as shown in Fig. 4.

[0048] When the steel cord 13 in the reinforcing layer 11 receives a magnetic field, eddy currents are generated in the steel cord 13. Since the eddy currents generated when receiving a high-frequency magnetic field are generated in the region up to a specific skin depth of the magnetic field, if the steel cord 13 is a stranded wire composed of a plurality of filaments, the surface area of the steel cord increases, and the loss due to eddy currents tends to increase. Here, the skin depth of the magnetic field refers to the penetration depth of the magnetic field from the surface until the high-frequency external excitation magnetic field strength decays to 1 / e (e: the base of the natural logarithm) of the magnetic field strength from the surface due to the eddy currents in the material.

[0049] On the other hand, the steel cord 13 suppresses eddy current loss to a minimum by consisting of 6 or less filaments. Therefore, the tire 10 is provided with a reinforcing layer 11 formed using a steel cord 13 consisting of 6 or less filaments, thereby suppressing a decrease in power supply efficiency as a result.

[0050] [Additional Form 7] In the basic form 1 or the form in which any one of additional forms 2 to 6 is added to the basic form 1, it is preferable that the winding width of the power receiving coil 40 is larger than the interval between adjacent steel cords 13 included in the reinforcing layer 11 (Additional Form 7).

[0051] As shown in FIG. 5, in the power receiving coil 40, the conducting wires are aligned along the surface of the reinforcing layer 11. The winding width WC refers to the length in the direction orthogonal to the longitudinal direction of the conducting wires of the power receiving coil 40 and in the direction in which the conducting wires are aligned.

[0052] Since the magnetic field passing through the reinforcing layer 11 can sufficiently interlink with the power receiving coil 40 when the winding width WC of the power receiving coil 40 is larger than the interval WG between the steel cords 13, a decrease in power feeding efficiency can be suppressed. The magnification of the winding width WC with respect to the interval WG between the steel cords 13, that is, the value obtained by dividing the winding width WC by the interval WG between the steel cords 13 (winding width WC / interval WG) is preferably 1.1 or more and 30 or less. When the above value is 1.1 or more, the magnetic field can sufficiently interlink with the power receiving coil 40, and when it is 30 or less, it is possible to suppress the power receiving coil 40 from becoming too large. Note that the power receiving coil 40 includes the case where the number of turns of the winding is 1 or more. When the number of turns is 1, the above winding width WC is the wire diameter of the winding.

[0053] [Additional Form 8] In the basic form 1 or the form in which any one of additional forms 2 to 7 is added to the basic form 1, it is preferable that the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 and the frequency f (kHz) of the supplied magnetic field satisfy the following formula (1) (Additional Form 8).

[0054] 4 ≦ f × WD ≦ 60 ··· (1)

[0055] As shown in FIG. 6, when the power receiving coil 40 is provided at the position 40A on the inner surface of the tread portion D, the distance WD between the reinforcing layer 11 and the power receiving coil 40 is the distance in the tire radial direction between the inner surface in the tire radial direction of the belt layer 20a provided at the innermost side in the tire radial direction and the outer surface in the tire radial direction of the power receiving coil 40. Further, when the power receiving coil 40 is provided at the position 40B on the inner surface of the tire on the side opposite to the tire side surface, it is the shortest distance between the inner surface in the tire width direction of the steel rain force 33 and the outer surface in the tire width direction of the power receiving coil 40. Further, when the power receiving coil 40 is provided at the position 40D on the inner surface of the tire via the fixing member 42, the distance WD between the reinforcing layer 11 and the power receiving coil 40 is the shortest distance between the inner surface in the tire radial direction of the belt layer 20a provided at the innermost side in the tire radial direction and the outer surface in the tire radial direction of the power receiving coil 40, including the thickness of the fixing member 42.

[0056] The lower the frequency of the magnetic field, the longer the wavelength, and it is difficult to pass through the gap of the metal, but the attenuation per distance is small. On the other hand, the higher the frequency of the magnetic field, the shorter the wavelength, and it is easy to pass through the gap of the metal, but the attenuation per distance is large. Further, the magnetic field attenuates as it moves away from the reinforcing layer 11, but it is difficult to efficiently link with the power receiving coil 40 if it is too close to the reinforcing layer 11.

[0057] With reference to FIGS. 7 and 8, the relationship between the interval WG between the steel cords 13, the distance WD between the reinforcing layer 11 and the power receiving coil 40, the frequency f, and the power feeding efficiency will be described below. FIGS. 7 and 8 are schematic diagrams showing the relationship between the reinforcing layer 11, the power receiving coil 40, and the magnetic field. Although the power transmission coil is not shown in FIGS. 7 and 8, it is provided at a sufficiently distant position from the reinforcing layer 11. The power transmission coil generates an alternating magnetic field with a predetermined frequency f. The alternating magnetic field passes through the interval WG between the steel cords 13 of the reinforcing layer and links with the power receiving coil 40. That is, the power receiving coil 40 resonates at the same frequency as the frequency f, and a current flows.

[0058] As shown in FIG. 7, if the distance WD between the power receiving coil 40 and the reinforcing layer 11 is too close to the interval WG between the steel cords 13, the strength of the magnetic field received at the position of the power receiving coil 40 will vary greatly depending on the position of the power receiving coil 40. Therefore, depending on the position where the power receiving coil 40 is attached during manufacturing, the received power may become extremely small, and the variation in power supply efficiency among products may increase. Further, since the power receiving coil 40 receives the magnetic field passing through the interval between the steel cords 13, if it is too close to the reinforcing layer 11, the magnetic flux passing through without linking with the power receiving coil 40 increases, so the linked magnetic flux relatively decreases.

[0059] As shown in FIG. 8, as the distance WD between the power receiving coil 40 and the reinforcing layer 11 increases with respect to the interval WG between the steel cords 13, the power receiving coil 40 receives the magnetic field passing through the interval WG between the steel cords 13 from a wider range. When the distance WD between the reinforcing layer 11 and the power receiving coil 40 is appropriate, the power receiving coil 40 can link with a large amount of magnetic flux, the magnitude of the received power depending on the position where the power receiving coil 40 is attached is stabilized, and the variation in power supply efficiency among products can be reduced. Incidentally, if the distance WD between the power receiving coil 40 and the reinforcing layer 11 is too large, the magnetic field becomes weak, so the power supply efficiency decreases.

[0060] By satisfying the above formula (1) with the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 and the frequency f (kHz) of the magnetic field supplied from the power transmission coil, a power receiving coil can be provided at a position where the magnetic field easily reaches, so that a decrease in power supply efficiency can be more reliably suppressed. That is, by 4 ≦ f × WD, the variation in received power depending on the position where the power receiving coil 40 is attached can be suppressed. By f × WD ≦ 60, the power receiving coil 40 can link with more magnetic flux.

[0061] [Additional Form 9] In the basic form 1 or the form in which any one of the additional forms 2 to 8 is added to the basic form 1, the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 is preferably 2.0 times or more and 25 times or less of the interval WG between the adjacent steel cords 13 included in the reinforcing layer 11 (additional form 9), and more preferably 2.5 times or more and 20 times or less.

[0062] When the power receiving coil 40 is provided on the inner surface of the tread portion, the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 is 2.0 times or more and 25 times or less of the interval WG between the adjacent steel cords 13 included in the belt 20. When the power receiving coil 40 is provided on the inner surface of the tire on the side opposite to the tire side surface, the distance WD (m) is 2.0 times or more and 25 times or less of the interval between the adjacent steel cords when included in the reinforcing layer 11 of the sidewall portion B, that is, the steel reinforcement 33. By the above value being 2.0 times or more, the variation in the received power depending on the position where the power receiving coil 40 is attached can be suppressed. By the above value being 25 times or less, since the magnetic field has a sufficient strength, it more surely links with the power receiving coil 40.

[0063] Regarding the distance WD (m) between the reinforcing layer 11 and the power receiving coil 40 and the interval WG between the adjacent steel cords 13, by the value of "WD / WG" being within the above range, it is possible to prevent the size of the fixing member 42 for fixing the power receiving coil 40 to the inner surface of the tire from becoming excessive, and more surely suppress the decrease in the power feeding efficiency.

[0064] [Additional form 10] In the basic form 1 or the form in which any one of the additional forms 2 to 9 is added to the basic form 1, the reinforcing layer 11 has a plurality of main portions 43 with the interval between the adjacent steel cords 13 being W1, and a void portion 45 disposed between the plurality of main portions 43. The interval between the adjacent plurality of main portions 43 in the void portion 45 is W2, and the interval W2 is preferably 1.5 times or more and 3.5 times or less of the interval W1 (additional form 10), and more preferably 1.8 times or more and 3.0 times or less.

[0065] As shown in FIGS. 9(A) and 9(B), the reinforcing layer 11 has a plurality of steel cords 13 arranged at regular intervals. The reinforcing layer 11 has a plurality of main portions 43. The plurality of main portions 43 are arranged with a gap portion 45 therebetween. The main portion 43 has a distance W1 between adjacent steel cords. The plurality of main portions 43 are each formed of approximately the same number of steel cords 13. The gap portion 45 is arranged between the main portions 43. The gap portion 45 maintains a distance W2 between adjacent main portions 43. By satisfying “1.5 ≦ (W2 / W1) ≦ 3.5” for the distance W1 and the distance W2, a gap portion 45 where no steel cord 13 exists at a predetermined interval is formed. That is, the reinforcing layer 11 allows the magnetic field to pass through more easily by the amount of the gap portion 45. Therefore, the tire 10 can suppress a decrease in power feeding efficiency. When the distance W2 is 1.5 times or more the distance W1, the magnetic field can easily pass through the reinforcing layer 11. When the distance W2 is 3.5 times or less the distance W1, the reinforcing layer 11 can sufficiently reinforce the tire structure.

[0066] [Additional Form 11] In the basic form 1 or the form in which any one of the additional forms 2 to 10 is added to the basic form 1, the reinforcing layer 11 is the belt 20 provided in the tread portion D, and a power receiving coil 40 is provided on the inner surface of the tire in the tire radial direction inside with respect to the belt 20. It is preferable that the power receiving coil 40 is a loop coil centered on the tire rotation axis (Additional Form 11).

[0067] As shown in FIG. 10, the power receiving coil 40 is provided on the inner surface of the tire in the tire radial direction inside with respect to the belt 20. FIG. 10 is a tire meridian sectional view in which the power receiving coil 40 is arranged at a position 40A approximately at the center in the tire width direction of the inner surface of the tire corresponding to the tread portion. The power receiving coil 40 is a loop coil, and as shown in FIG. 11, a conductor is wound in a cylindrical shape around the tire rotation axis so as to be aligned in the circumferential direction of the tire width direction along the inner surface of the tire corresponding to the tread portion. The number of turns of the power receiving coil 40 is preferably 1 to 5 times. The diameter of the conductor of the power receiving coil 40 is preferably 0.5 to 1.2 mm.

[0068] By providing the power receiving coil 40 on the inner surface of the tire corresponding to the tread portion D, the distance from the power transmitting coil provided on the outer side in the tire radial direction becomes closer, and the power supply efficiency can be increased. Therefore, when the power transmitting coil is provided on the outer side in the tire radial direction, the tire 10 can suppress a decrease in the power supply efficiency.

[0069] The power receiving coil 40 may be provided in a region on the inner side in the tire width direction with respect to the pair of outer circumferential main grooves 38, that is, on the inner surface of the tire corresponding to the center land portion 35. By providing the power receiving coil 40 on the inner surface of the tire corresponding to the center land portion 35, heat generation on the inner surface of the tire is lower, so the heat of the power receiving coil 40 is easily dissipated, and the durability is excellent.

[0070] As shown in FIG. 12, the power receiving coil 40 may be provided at a position 40K on the inner surface of the tire corresponding to the shoulder land portion 37. The power receiving coil 40 is a loop coil, and as shown in FIG. 13, the conductor is wound in a cylindrical shape around the tire rotation axis so as to be aligned in the tire width direction along the inner surface of the tire corresponding to the shoulder land portion 37. The magnetic field generated by the power transmitting coil not only passes through the interval WG between the steel cords 13 of the belt layer 11, but also reaches the power receiving coil 40 so as to wrap around the tire width direction end portion of the belt layer 11 from the outer side in the belt width direction. Since the shoulder land portion 37 is close to the sidewall portion B with less metal material, by providing the power receiving coil 40 on the inner surface of the tire corresponding to the shoulder land portion 37, the power receiving coil 40 is less affected by the steel cord 13 of the belt layer 11 in power supply from the outer side in the tire width direction or the outer side in the tire radial direction. That is, since the magnetic field interlinking with the power receiving coil 40 is hardly blocked by the steel cord 13 of the belt layer 11, the tire 10 can suppress a decrease in the power supply efficiency.

[0071] [Additional Form 12] In the basic form 1 or the form in which any one of the additional forms 2 to 10 is added to the basic form 1, the reinforcing layer 11 is provided in the tire radial direction region from the end of the belt 20 in the tire width direction to the outermost position of the bead core 14 in the tire radial direction. In the tire meridian cross-sectional view in the unloaded state, when the tire radial length from the bead toe 32 to the tread surface 34 is SH, a power receiving coil 40 is provided at the position 40B on the inner surface of the tire in the region within 50% of the tire radial length SH from the bead toe 32. The power receiving coil 40 is preferably a loop coil centered on the tire rotation axis (Additional form 12).

[0072] The tire radial length SH is the tire radial length from the bead toe 32 to the tread surface 34 in the state where the tire is mounted on a rim and a normal internal pressure is applied and in the unloaded state. As shown in FIG. 14, the power receiving coil is arranged at a position within 50% of the tire radial length SH from the bead toe 32. At least a part of the power receiving coil 40 overlaps with the steel reinforcement 33 in the tire radial direction. The power receiving coil 40 is a loop coil, and as shown in FIG. 15, a conducting wire is wound around the tire rotation axis so as to be aligned in the tire radial direction along the inner surface of the tire corresponding to the sidewall portion B. The power receiving coil 40 may be wound in a spiral shape. The number of turns of the power receiving coil 40 is preferably 1 to 5 turns. The diameter of the conducting wire of the power receiving coil 40 is preferably 0.5 to 1.2 mm.

[0073] By providing it on the inner surface of the tire corresponding to the sidewall portion B within the above range, the distance from the power transmission coil provided on the outer side in the tire width direction becomes closer, and the power supply efficiency can be improved. Therefore, when the tire 10 is provided with a power transmission coil on the outer side in the tire width direction, a decrease in power supply efficiency can be suppressed. Further, since the power receiving coil 40 is provided on the inner surface of the tire in the region within 50% of the tire radial length SH from the bead toe 32, the influence of the deformation of the tire 10 on the power receiving coil 40 is suppressed, and the power receiving coil 40 is less likely to fall off from the inner surface of the tire, improving durability.

[0074] [Additional form 13] In the basic form 1 or the form in which any one of the additional forms 2 to 12 is added to the basic form 1, it is preferable that it is in a state assembled to the regular rim (additional form 13).

[0075] The tire 10 is used by being assembled to the rim 6. In this case, as shown in FIG. 1, the power receiving coil 40 may be provided on the rim 6. For example, the power receiving coil 40 may be provided at the position 40E on the inner surface of the rim facing the inner cavity surface of the tire as shown in FIG. 1. The power receiving coil 40 may be wound in a cylindrical shape with the conductors aligned in the tire width direction. In another example, the power receiving coil 40 may be provided at the position 40F on the outer surface of the rim on the side opposite to the inner surface of the rim facing the inner cavity surface of the tire. In still another example, as shown in FIG. 3, the power receiving coil 40 is provided at the position 40G on the inner surface of the rim facing the inner cavity surface of the tire, and may be wound in a spiral shape so that the conductors are aligned in the tire radial direction.

[0076] <Wireless power supply system> [Basic form 14] FIG. 16 is a diagram showing the wireless power supply system 50 according to the present embodiment, the power transmission coil 52, and the tire 10 provided with the power receiving coil 40 (a portion on one side in the tire width direction with respect to the tire equatorial plane CP in a tire meridian cross-sectional view). Note that FIG. 16 shows the tire portion on the side opposite to the ground contact surface in a state where the rim is assembled and the 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).

[0077] The power transmission coil 52 shown in the figure constitutes a resonance circuit by 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 steering axle of a vehicle (not shown), for example, or any component constituting a strut structure.

[0078] Next, the power receiving coil 40 shown in FIG. 16 has the same configuration as the power receiving coil shown in FIG. 1, and forms a resonance circuit with a capacitor and a coil. Note that the tire 10 shown in FIG. 16 is a tire of basic form 1 regarding the above-described tire 10 and a tire obtained by adding at least any one of additional forms 2 to 13 to basic form 1, and its actions, functions, etc. are as described above.

[0079] Under such a premise, the wireless power supply system 50 according to the present embodiment is a wireless power supply using a magnetic field resonance method using an alternating magnetic field. As shown in FIG. 16, power is supplied to the power transmission coil 52, and the power is transmitted to the power receiving coil 40 by the alternating magnetic field. According to such a wireless power supply system 50, as described above, the power supply efficiency can be improved.

[0080] Here, in order to drive the 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. More preferably, the power transmission coil 52 is supplied with alternating current power having a frequency of 6.78 to 13.56 MHz.

[0081] Also, the shortest distance between the power transmission coil 52 and the power receiving 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 rim-mounted, normal internal pressure is applied, and the vehicle is attached and stopped on a flat ground. The transmission gap G refers to the shortest distance between the power transmission coil 52 and the power receiving coil 40, that is, in FIG. 16, 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 receiving coil 40.

[0082] By setting the transmission gap G to 10 mm or more, it is possible to suppress an 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. 16 in the power transmission direction, simplify the circuit configuration connected to the power reception coil 40, and thus easily supply stable power to an 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, causing the relative position between the two coils 52 and 40 to vary. Specifically, the higher the tire rolling speed, the more the tire 10 expands in the tire radial direction, causing the power reception coil 40 to move to the outside in the tire radial direction (the upper side in FIG. 16), while the position of the power transmission coil 52 remains unchanged, resulting in a change in the relative position between the two coils 52 and 40.

[0083] On the other hand, by setting the transmission gap G to 80 mm or less, the strength of the magnetic field generated between the two coils 52 and 40 does not become excessively small, and power feeding by the alternating magnetic field can be efficiently performed.

[0084] It is more preferable that the transmission gap G is 12 mm or more and 75 mm or less, and extremely preferably 15 mm or more and 70 mm or less.

[0085] By adopting the above-described range of the transmission gap G, power range, and frequency band, not only can the temperature rise of the power reception coil 40 be suppressed, but also an increase in the number of turns of the coil etc. (and thus an increase in coil weight) is not required, the rolling resistance of the tire is not increased, power feeding can be efficiently performed, and thus excellent power feeding efficiency can be realized. In particular, according to the above-described range of the transmission gap G, excellent power feeding efficiency can be obtained when power is transmitted using the tire structure in magnetic field resonance type wireless power feeding in the above frequency band.

[0086] In the example shown in FIG. 16, the power transmission coil 52 is arranged to extend in the tire diameter direction, but the present embodiment is not limited to such an arrangement form. That is, as long as the above-described transmission gap G is within a predetermined range, the extending direction of the power transmission coil 52 may be inclined with respect to the tire diameter direction.

[0087] [Additional Embodiment 15] FIG. 17 is a diagram showing that the power receiving coil 40 is located within the power supply region of the power transmission coil 52 for the wireless power supply system 50 according to the present embodiment. (A) and (B) show examples where the power supply direction is the tire width direction, and (C) and (D) show examples where the power supply direction is inclined downward with respect to the tire width direction. In FIG. 5, (A) and (C) are examples in which the radially inner portion of the tire diameter of the power receiving coil 40 is included in the power supply region of the power transmission coil 52, and (B) and (D) are examples in which the radially outer portion of the tire diameter of the power receiving coil 40 is included in the power supply region of the power transmission coil 52.

[0088] In Basic Embodiment 14, as shown in FIGS. 5(A) to 5(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 supply region extending in the winding axis direction of the power transmission coil 52 between both longitudinal ends of the power transmission coil 52 (Additional Embodiment 15).

[0089] Here, the positional relationship between the power receiving coil 40 and the power transmission coil 52 is measured in a state where the tire 10 is rim-mounted, a normal internal pressure is applied, and the vehicle is mounted and stopped on a flat ground. More preferably, the power transmission coil radial direction region defined by the length between both tire diameter direction ends of the power transmission coil 52 is arranged so as to overlap at least a part of the power receiving coil radial direction region defined by the length between both tire diameter direction ends of the power receiving coil 40. By such an arrangement, higher power supply efficiency can be realized.

[0090] The power transmission coil 52 shown in FIGS. 17(A) and 17(B) is disposed at a position on the outer side in the tire width direction corresponding to a partial region in the tire circumferential direction. Note that the power reception coil 40 provided on the inner cavity surface of the tire extends over the entire circumference in the tire circumferential direction. At least a part of the power reception coil 40 is provided in a region obtained by projecting the power transmission coil radial direction region onto the inner cavity surface of the tire, that is, a region between points where virtual lines parallel to the winding axis of the power transmission coil 52, which extend from the outer end and the inner end in the tire radial direction of the power transmission coil 52 to the inner cavity surface of the tire, intersect the inner cavity surface of the tire. It is preferable that a part of the power reception coil 40 in the tire radial direction is included in the region obtained by projecting the above power transmission coil radial direction region, and it is more preferable that the entire power reception coil 40 in the tire radial direction is included in the region obtained by projecting the above power transmission coil radial direction region.

[0091] 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 (located on the outer side in the tire width direction of the sidewall portion B) that is a component of the steering axle of the vehicle, or to the tire-side surface of any component constituting the strut structure. Therefore, when considering the power supply efficiency in view of the shape of the tire, particularly the sidewall portion B of the tire 10, as shown in FIGS. 17(A) and 17(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, is substantially the tire width direction.

[0092] In accordance with such findings, as shown in FIGS. 17(A) and 17(B), when the power supply direction Dp is substantially the tire width direction, power supply can be performed more efficiently, and thus excellent power supply efficiency can be achieved.

[0093] Further, in the examples shown in FIGS. 17(B) and 17(C), for each of the power transmission coil 52 and the power reception coil 40, the constituent surfaces (planes having the winding axes of the respective coils as normal lines in FIGS. 17(B) and 17(C)) are parallel to each other. Therefore, compared with the example shown in FIGS. 17(A) and 17(D), power supply can be performed more efficiently, and thus excellent transmission efficiency can be achieved.

[0094] Note that, as shown in FIGS. 17(A) and 17(D), the power transmission coil 52 and the power reception coil 40 do not necessarily have their constituent surfaces parallel to each other. The reason is that if the magnetic field generated by the power transmission coil 52 links with the power reception coil 40, an electromotive force is generated by the alternating magnetic field, and there is no restriction on the relative orientation of the above-mentioned surfaces.

[0095] [Additional Form 16] In the basic form 14 or the form obtained by adding the additional form 15 to the basic form 14, 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 (Additional Form 16).

[0096] Normally, when the tire 10 rolls, at the grounding portion of the tire 10, the power reception coil 40 deforms along with the deformation of the tire 10. On the other hand, at a portion away from the grounding portion of the tire 10 (the upper portion of the tire 10 in FIG. 18), almost no deformation of the power reception coil 40 due to the tire deformation is observed. For this reason, by installing the power transmission coil 52 arranged outside the tire 10 near the upper portion of the tire away from the installation portion of the tire 10 (the tire circumferential direction range R of 60° on both sides of the imaginary line extending vertically upward from the tire center O), during tire rolling, the fluctuation of the above-mentioned transmission gap G can be suppressed, power supply can be performed more efficiently, and furthermore, more excellent power supply efficiency can be realized. Note that the example shown in FIG. 18 is an example of attaching the power transmission coil 52 to the wheel house 54, and the above-mentioned tire circumferential direction range R is applied within the wheel house 54.

[0097] It is more preferable that the power transmission coil 52 is installed within a tire circumferential direction range of 55° on both sides of an imaginary line extending vertically upward from the tire center O, and it is extremely preferable that the power transmission coil 52 is installed within a tire circumferential direction range of 50° on both sides of the imaginary line.

[0098] Further, the shape of the power transmission coil 52 is not particularly limited. However, when the power transmission coil 52 is installed, for example, inside the wheel house, it is preferably a so-called spiral coil that can reduce the overall thickness. <Other embodiments 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.

[0099] The carbon content of the inner liner 12, which is a component of the tire 10, is 45 to 75 parts by mass (parts by mass when the rubber is 100, the same applies hereinafter). The carbon content of the side tread is 25 to 65 parts by mass, the carbon content of the bead filler 16 is 40 to 80 parts by mass, and the carbon content of the covering rubber of the carcass 18 is preferably 35 to 70 parts by mass. By adopting these respective compounding amounts, it is possible to realize the desired thermal conductivity in each rubber layer and, at the same time, realize each performance of the tire described above. Usually, the thermal conductivity of rubber is determined by the polymer type and compounding agent. However, it is most preferable to adjust the carbon content because it is easy to change the electrical properties (since carbon particles themselves have high conductivity) and it is easy to balance with the properties of the rubber required for the tire.

[0100] Regarding the wireless power supply system 50 shown in FIG. 16, the power receiving coil 40 is preferably provided in the tire inner cavity 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. 17(A) and 17(B), when the power supply direction by the power transmission 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 transmission surface of the power transmission coil 52 and the configuration surface of the power receiving coil 40 become parallel. Thereby, power supply can be performed more efficiently, and thus excellent power supply efficiency can be realized.

[0101] FIG. 19 is a diagram showing the arrangement mode of the power receiving coil 40. (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 diameter direction. (H) is an example in which a part of the plurality of power receiving coil elements 40a extends obliquely with respect to the tire diameter direction.

[0102] As shown in FIGS. 19(A) to (H), the power receiving coil 40 may be formed of a plurality of power receiving coil elements 40a. On the inner cavity surface of the tire 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 on the entire circumference of the tire 10, in this power receiving coil 40, there are a portion that is deformed and distorted (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 cavity surface of the tire. 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.

[0103] FIG. 20 is a tire meridian sectional view (however, half in the tire width direction) showing a power supply mode for supplying power from the power receiving coil 40 to the electronic device 46 attached to the inner cavity surface of the tire via the power line 44 in the tire 10.

[0104] As shown in FIG. 20, the power receiving coil 40 is connected to a capacitor (not shown) as a resonance circuit, and further supplies power to an electronic device 46 (such as a sensor, a signal processing circuit, a communication circuit, etc.) attached to the inner cavity surface of the tire via a power line 44 attached to the inner cavity surface of the tire. 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 material, there is no trouble due to the influence of the magnetic field. For this reason, the electronic device 46 is arranged on the inner cavity surface of the tire width direction region where the belt 20 having high rigidity is formed among the tires 10, the power receiving coil 40 is arranged on the inner cavity surface of the sidewall portion B where the power supply efficiency can be increased, and these 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 (the power receiving coil 40, the capacitor, the power line 44, and the electronic device 46) on the inner cavity surface of the tire, an increase in the manufacturing cost and the manufacturing difficulty of the tire 10 is suppressed.

Example

[0105] Hereinafter, a comparison of the predetermined effects of the present application among the inventions defined in the claims of the present application (hereinafter referred to as "Invention Examples 1 to 5") will be described.

[0106] The tire size was set to 245 / 40R19 (specified by JATMA), and the tire shown in FIG. 1 was manufactured. The conditions of the tires 10 in Examples 1 to 10 are as shown in Table 1 below.

[0107]

Table 1

[0108] The "area ratio (SR / S)", "distance between steel cords (mm)", "cross-sectional perimeter (mm)", "number of filaments", "winding width / spacing", "f×D", "D / spacing", and "W2 / W1" in Table 1 conform to the definitions described in this specification.

[0109] Regarding the wireless power supply system using the tires of Invention Examples 1 to 5 manufactured as described above, the ratio (power transmission efficiency) of the power 2 received by the receiving coil (and the resonance circuit of the capacitor) to the power 1 transmitted from the transmitting coil was measured, and these ratios were expressed as indices when Invention Example 1 was set to 100. The measurement of the ratio of power 1 and 2 was performed using a vector network analyzer. The results are also shown in Table 1.

[0110] According to Table 1, it can be seen that all of 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

[0111] 6 Rim 8 Rim flange 10 Tire 11 Reinforcing layer 12 Inner liner 13 Steel cord 14 Bead core 15 Rubber part 16 Bead filler 18 Carcass 18a Body part 18b Turn-up part 20 Belt (reinforcing layer) 20a Belt layer 20b Belt layer 22 Belt cover 22a Belt cover layer 22b Belt cover layer 24 Rim cushion 26 Side tread 29 Second carcass 29a Body part 29b Turn-up part 30 Cap tread 31 Bead reinforcing layer 32 Bead toe 33 Steel rayon reinforcement (reinforcing layer) 34 Tread surface 35 Center land part 36 Circumferential main groove 37 Shoulder land part 38 Outer circumferential main groove 40 Power receiving coil 40a Power receiving coil element 42 Fixing member 43 Main part 44 Power line 45 Gap part 46 Electronic device 50 Power supply system 52 Power transmission coil 54 Wheel house A Bead part B Side wall part C Shoulder part D Tread part WC Coil width WG Gap WD Distance between the reinforcing layer and the power receiving coil S Area SR Surface area of the rubber part SH Tire radial length

Claims

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

2. The reinforcing layer is a belt provided in the tread portion, and the area ratio of the portion excluding the steel cords to the area of the belt in a front view is 0.1 or more and 0.5 or less. The tire according to claim 1.

3. The reinforcing layer is provided in a tire radial direction region from an end portion of the belt in the tire width direction to the outermost position of the bead core in the tire radial direction, and the area ratio of the portion excluding the steel cords to the area of the reinforcing layer in a front view is 0.3 or more and 0.7 or less. The tire according to claim 1.

4. The distance between adjacent steel cords included in the reinforcing layer is 0.4 mm or more and 2.4 mm or less. The tire according to claim 1.

5. The cross-sectional perimeter orthogonal to the longitudinal direction of the steel cord is 1.5 mm or more and 7.0 mm or less. The tire according to claim 1.

6. The steel cord is composed of 1 or more and 6 or less filaments. The tire according to claim 1.

7. The winding width of the power receiving coil is larger than the distance between adjacent steel cords included in the reinforcing layer. The tire according to claim 1.

8. The distance WD (m) between the reinforcing layer and the power receiving coil and the frequency f (kHz) of the supplied magnetic field satisfy the following formula (1). The tire according to claim 1. 4 ≤ f × WD ≤ 60... (1)

9. The distance WD (m) between the reinforcing layer and the power receiving coil is 2.0 times or more and 25 times or less the distance between adjacent steel cords included in the reinforcing layer. The tire according to claim 1.

10. The reinforcing layer has a plurality of main portions with a distance W1 between adjacent steel cords, and a void portion disposed between the plurality of main portions. The distance between adjacent main portions in the void portion is W2, and the interval W2 is 1.5 times or more and 3.5 times or less the interval W1. The tire according to claim 1.

11. The reinforcing layer is a belt provided in the tread portion, the power receiving coil is provided on the inner surface of the tire on the inner side in the tire radial direction with respect to the belt, the power receiving coil is a loop coil centered on the tire rotation axis, the tire according to claim 1.

12. The reinforcing layer is provided in a region in the tire radial direction from the end portion of the belt in the tire width direction to the outermost position in the tire radial direction of the bead core, when the tire radial length from the bead toe to the tread surface is SH in a tire meridian cross-sectional view of the tire in an unloaded state, the power receiving coil is provided on the inner surface of the tire in a region within 50% of the tire radial length SH from the bead toe, the power receiving coil is a loop coil centered on the tire rotation axis, the tire according to claim 1.

13. The tire according to any one of claims 1 to 12 in a state assembled to a standard rim.

14. A wireless power feeding system that supplies AC power to a power transmission coil that constitutes a resonance circuit by a capacitor and a coil, and transmits power to the power receiving coil that constitutes a resonance circuit by the capacitor and the coil, the wireless power feeding system including the tire according to claim 1 or 2.

15. The wireless power feeding system according to claim 14, wherein at least a part of the power receiving coil is located in a power feeding region that extends 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.

16. The wireless power feeding system according to claim 14, wherein the power transmission coil is installed in a range of 60° on both sides in the tire circumferential direction centered on an imaginary line extending vertically upward from the center of the tire.

Images