Tire and wireless power supply system

Abstract

To provide a tire which is excellent in durability of a power incoming coil, and a wireless power supply system using the tire.SOLUTION: A tire 10 comprises: a tread part D provided with a belt 20; a bead part A provided with a toric bead core 14; a pair of side wall parts B provided between the tread part D and the bead part A; a power incoming coil 40 formed by a conducting wire which receives electric power supplied by an AC magnetic field from the exterior of the tire 10; and a plurality of fixing members 41 which fix the power incoming coil 40 to a tire cavity surface 13. The power incoming coil 40 has a fixed part 44, which is fixed to the tire cavity surface 13 by the fixing member, and a non-fixed part 45, which is not fixed to the tire cavity surface 13, in a longer direction of the conducting wire.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, a wireless power receiving system has been proposed that supplies power between a power transmitting coil provided in a vehicle body and a power receiving coil attached to a tire. The power receiving coil is provided, for example, along the tire cavity surface facing the tire cavity region (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-29235 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a wireless power receiving system, the power receiving coil provided in the tire is deformed repeatedly together with the tire, and therefore is desired to have excellent durability.

[0005] An object of the present invention is to provide a tire having a power receiving coil with excellent durability and a wireless power supply system using the tire. [Means for solving the problem]

[0006] The tire of the present invention comprises a tread portion provided with a belt, a bead portion provided with an annular bead core, a pair of sidewall portions provided between the tread portion and the bead portion, a receiving coil formed of a conductor that receives power supplied by an AC magnetic field from outside the tire, and a plurality of fixing members that fix the receiving coil to the tire cavity surface, wherein the receiving coil has, in the longitudinal direction of the conductor, a fixed portion fixed to the tire cavity surface by the fixing members and a non-fixed portion that is not fixed to the tire cavity surface. [Effects of the Invention]

[0007] The tire and wireless power supply system according to the present invention have excellent durability of the power receiving coil. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a portion on one side in the tire width direction with respect to the tire equatorial plane in a tire meridian cross section of the contact patch side of a tire according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the positional relationship between the power receiving coil and the fixing member according to this embodiment, as viewed from the inner side in the tire width direction. [Figure 3] FIG. 3 is a partial cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a diagram showing a portion on one side in the tire width direction with respect to the tire equatorial plane in a tire meridian cross section of the contact patch side of a tire according to a modified example of this embodiment. [Figure 5] FIG. 5 is a schematic diagram showing a power receiving coil according to a modified example of the present embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a part of a power receiving coil according to a modification of the present embodiment. [Figure 7] 7A to 7D are partial cross-sectional views schematically showing modified examples of the power receiving coil provided in the tire of this embodiment, where (A) is Modified Example 1, (B) is Modified Example 2, (C) is Modified Example 3, and (D) is Modified Example 4. [Figure 8]FIG. 8 is a diagram showing a wireless power supply system according to this embodiment, illustrating a power transmitting coil and a tire in which a power receiving coil is provided (a portion on one side in the tire width direction relative to the tire equatorial plane in a tire meridian cross section on the non-ground contact side). [Figure 9] 9A and 9B are diagrams showing that the receiving coil is located within the power supply area of ​​the transmitting coil in the wireless power supply system according to this embodiment, where (A) and (B) show an example in which the power supply direction is the tire width direction, and (C) and (D) show an example in which the power supply direction is inclined relative to the tire width direction. [Figure 10] FIG. 10 is a diagram showing the installation position of the power transmitting coil in the wireless power supply system according to this embodiment. [Figure 11] FIG. 11 is a partial meridional cross-sectional view showing the installation positions of the power transmitting coil and the power receiving coil in the wireless power feeding system according to this embodiment. [Figure 12] Figure 12 shows an arrangement of receiving coils (an arrangement in which the receiving coils are not continuous in the tire circumferential direction, unlike in Figure 1), where (A) to (F) are examples showing receiving coils 40 consisting of 2, 3, 4, 5, 6, and 8 loop coil sections 40a, respectively, (G) is an example in which multiple loop coil sections 40a are stacked in the tire radial direction, and (H) is an example in which some of the multiple loop coil sections extend at an angle relative to the tire radial direction. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments of the present invention relate to the following aspects.

[0010] [Aspect 1] A tire comprising: a tread portion provided with a belt; bead portions provided with annular bead cores; a pair of sidewall portions provided between the tread portion and the bead portions; a power receiving coil formed of a conductor that receives power supplied by an AC magnetic field from outside the tire; and a plurality of fixing members that fix the power receiving coil to a tire inner cavity surface, the power receiving coil has, in the longitudinal direction of the conductor, a fixed portion fixed to the tire cavity surface by the fixing member, and a non-fixed portion not fixed to the tire cavity surface.

[0011] [Aspect 2] the power receiving coil has a loop coil portion made of a loop coil, the loop coil portion is disposed in the side region, The tire according to aspect 1, wherein the side region is a region in a meridian cross section of the tire between a first perpendicular line drawn from an outer end of the bead core in the tire radial direction to a tire cavity surface in a normal direction to the tire cavity surface, and a second perpendicular line drawn from an outer end of the belt in the tire width direction to a tire cavity surface in a normal direction to the tire cavity surface.

[0012] [Aspect 3] A tire according to aspect 1 or 2, wherein the fixing member has a hardness lower than that of the rubber layer exposed to the tire cavity.

[0013] [Aspect 4] The tire according to any one of aspects 1 to 3, wherein the number n of the fixing members, the length LC of the tread portion in the tire circumferential direction, and the tire cross-sectional height SH satisfy the following formula (1):

[0014]

number

[0015] [Aspect 5] The tire according to any one of aspects 1 to 4, wherein the receiving coil has a loop coil portion consisting of a loop coil with one turn centered on the tire rotation axis, and the loop coil portion is installed on the tire inner cavity surface corresponding to the sidewall portion.

[0016] [Aspect 6] the power receiving coil has a loop coil portion made of a loop coil and a lead-out portion formed of a conductor that connects the loop coil portion to an electronic circuit board, The tire according to aspect 2, wherein the lead-out portion has, in the longitudinal direction of the conductor, a second fixed portion fixed to the tire cavity surface by the fixing member, and a second non-fixed portion not fixed to the tire cavity surface.

[0017] [Aspect 7] The pull-out portion and the belt adjacent region intersect, The tire according to aspect 6, wherein, when the tire cross-sectional height is SH, the belt-adjacent region is an annular region whose outer edge is a position where a second perpendicular line drawn from a tire width direction side end of the belt in a direction normal to the tire cavity surface intersects with the tire cavity surface, and whose inner edge is a position spaced apart from the second perpendicular line along the tire cavity surface toward the bead portion by a length Fx expressed by the following formula (2): Fx = 0.12 × SH (2)

[0018] [Aspect 8] 8. The tire of embodiment 7, having the second fastening portion in the belt-adjacent region.

[0019] [Aspect 9] A tire according to aspect 7 or 8, wherein the fixing member fixes the pull-out portion to a tire cavity surface in a range from an outer edge to an inner edge of the belt-adjacent region.

[0020] [Aspect 10] A tire according to any one of aspects 7 to 9, further comprising a first additional reinforcing layer for suppressing deformation of the pulled-out portion, on the outer side in the tire radial direction of a portion where the belt on the outer side in the tire width direction has only one layer.

[0021] [Aspect 11] A tire according to any one of aspects 7 to 10, further comprising a second additional reinforcing layer on the outer side of the belt in the tire width direction, the second additional reinforcing layer suppressing deformation of the lead-out portion.

[0022] [Aspect 12] 12. The tire according to any one of aspects 1 to 11, mounted on a genuine rim.

[0023] [Aspect 13] 13. A wireless power supply system that supplies AC power to a power transmitting coil that forms a resonant circuit with a capacitor and a coil, and transmits the power to the power receiving coil that also forms a resonant circuit with a capacitor and a coil, the wireless power supply system including the tire according to any one of aspects 1 to 12.

[0024] [Aspect 14] Aspect 14. The wireless power transfer system according to aspect 13, wherein at least a portion of the receiving coil is located within a power transfer region extending in a winding axis direction of the transmitting coil across both longitudinal ends of the transmitting coil in a tire meridian cross section.

[0025] [Aspect 15] A wireless power transfer system according to aspect 13 or 14, wherein the power transmission side surface of the power transmission coil unit including the power transmission coil that faces the power receiving coil forms an angle with the tire radial direction as viewed from the tire meridian cross section within a range of 70° toward the tire and 30° toward the tire away from the tire, with the inner end of the power transmission coil unit in the tire radial direction as the center.

[0026] [Aspect 16] 16. The wireless power supply system according to any one of aspects 13 to 15, wherein the power transmitting coils are installed within a range of 60° on both sides in the tire circumferential direction, centered on an imaginary line extending vertically upward from the center of the tire.

[0027] 1. Tires (Tire composition) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis, the tire radially inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radially outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the tire rotational axis, the tire widthwise inner side refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and the tire widthwise outer side refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane refers to the plane that is perpendicular to the tire rotational axis and passes through the center of the tire width.

[0028] Similarly, in the following description, a regular rim refers to an "applicable rim" as defined by JATMA, a "design rim" as defined by TRA, or a "measuring rim" as defined by ETRTO.

[0029] Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Inflation Pressures" specified by ETRTO. Also, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Load Capacity" specified by ETRTO.

[0030] 1 is a diagram showing a portion on one side in the tire width direction with the tire equatorial plane CP as the reference in a tire meridian cross section of the contact patch side of a tire 10 according to this embodiment. Note that the drawing shows the tire portion on the contact patch side in a state where the tire is mounted on a rim and has a normal internal pressure applied, and is in an unloaded state.

[0031] As shown in Fig. 1, a tire 10 according to this embodiment includes a tire main body 11 and a power receiving coil 40. The tire main body 11 has, from the inner side to the outer side in the tire radial direction, a bead portion A, a sidewall portion B, a shoulder portion C, and a tread portion D. An inner liner 12 exposed to a tire cavity surface 13 is provided in the region from the bead portion A to the tread portion D, and a carcass 18 including a main portion 18a extending along the inner liner 12 and a folded portion 18b folded back around a bead core 14 and a bead filler 16 is provided on the opposite side from the tire cavity surface 13, and a belt 20 (belt layers 20a, 20b) is provided on the outer side in the tire radial direction of the carcass 18 in the tread portion D.

[0032] In the tire 10 configured as described above, the inner liner 12 is a layer for blocking gas coming into contact with the tire cavity surface 13. The inner liner 12 can be configured with a single inner liner layer, or can be configured with multiple inner liner layers laminated in the tire radial direction at the tire equatorial plane CP. The inner liner 12 includes at least one layer made of rubber or resin with low air permeability, and can include an adhesive layer at least in the portion in contact with the carcass 18 as other layers.

[0033] The bead core 14 is, for example, a ring-shaped reinforcing material made of bundled cords, and may have a structure in which a plurality of bead wires made of steel cords or organic fiber cords are covered with rubber. The bead filler 16 is a member for increasing the rigidity of the bead portion A, and may have a substantially inverted triangular shape as shown in Fig. 1, in which the tire width direction dimension at the tire radially inner end is substantially equal to the tire width direction dimension at the tire radially outer end of the bead core 14, and the tire width direction dimension gradually decreases toward the tire radially outer side.

[0034] The carcass 18 is a component that forms the framework of the tire 10 and is composed of at least one carcass layer (carcass ply), and each carcass layer is configured with a plurality of carcass cords coated with rubber. Generally, steel cords or organic fiber cords are used as the carcass cords. However, in the tire 10 according to this embodiment, as described below, it is preferable to use a non-magnetic material for the carcass cords in order to prevent a metal member from interfering with the magnetic field that is generated in the sidewall portion B so as to penetrate the tire cavity surface 13 of the inner liner 12 substantially perpendicularly. For example, organic fibers such as rayon, polyester, polyamide, and aramid can be used as the non-magnetic material.

[0035] The belt 20 is a reinforcing layer provided on the radially outer side of the carcass 18, and is a member that tightens the carcass 18 to increase the rigidity of the tread portion D, improves steering stability, and reduces strain deformation and rolling resistance. The belt 20 can be composed of multiple belt layers (two belt layers 20a, 20b in the example shown in FIG. 1) stacked in the radial direction of the tire in the tread portion D. Each of the belt layers 20a, 20b has a configuration in which multiple belt cords are covered with rubber. Generally, steel cords or organic fiber cords are used as the belt cords. As the belt cords, magnetic materials such as steel cords can of course be used, but non-magnetic materials (including paramagnetic materials and diamagnetic materials) can also be used.

[0036] The side tread 26 is arranged to connect the bead portion A and the tread portion D. The cap tread 30 is formed on a tread surface 34, which is the surface of the tread portion D, over the entire tire contact area. Both the side tread 26 and the cap tread 30 can use conventional rubber materials depending on the required characteristics of each.

[0037] The tire 10 according to this embodiment includes a power receiving coil 40 on the inner side in the tire width direction of the tire cavity surface 13, which receives AC power transmitted from a power transmitting coil (not shown) installed outside the tire 10. The power receiving coil 40 is fixed to the tire cavity surface 13 by a fixing member 41.

[0038] The power receiving coil 40 is formed of a conductor wire, for example, an electric wire made of copper, aluminum, or iron. The diameter of the conductor wire is preferably 0.5 to 1.2 mm. The conductor wire may be a solid wire or a stranded wire. In the present embodiment, the conductor wire is a solid wire. As shown in FIG. 2, the power receiving coil 40 has a loop coil portion 42 and a lead-out portion 43. In the loop coil portion 42, the conductor wire is wound around the tire rotation axis so as to be aligned in the tire circumferential direction along the tire cavity surface 13 corresponding to the tread portion D. The number of turns of the conductor wire in the loop coil portion 42 is preferably 1 to 5. The number of turns of the loop coil portion 42 shown in FIG. 2 is 1. The number of turns of the loop coil portion 42 is not limited to one or more complete turns in which both ends of the conductor wire cross each other, and the both ends of the conductor wire do not have to cross each other as shown in FIG. 2. The distance d1 between the two ends of the conductor when the two ends of the conductor do not intersect is not particularly limited, and may be, for example, 0.3% or more and 5.0% or less of the circumferential length of the loop coil portion 42, preferably 0.5% or more and 4.0% or less.

[0039] The loop coil portion 42 is preferably provided in a side region MS (FIG. 1) on the tire cavity surface 13. The side region MS refers to the region sandwiched between a first perpendicular line VT1 and a second perpendicular line VT2. The first perpendicular line VT1 is a perpendicular line extending from the tire radially outer end of the bead core 14 to the tire cavity surface 13 in a direction normal to the tire cavity surface 13. The second perpendicular line VT2 is a perpendicular line extending from the tire widthwise outer end of the belt 20 to the tire cavity surface 13 in a direction normal to the tire cavity surface 13. The side region MS is an annular region sandwiched between a first arc (not shown) connecting the intersections of the first perpendicular line VT1 and the tire cavity surface 13 in the tire circumferential direction, and a second arc (not shown) connecting the intersections of the second perpendicular line VT2 and the tire cavity surface 13 in the tire circumferential direction.

[0040] The loop coil portion 42 has a plurality of fixed portions 44 fixed to the tire cavity surface 13 and a plurality of non-fixed portions 45 that are not fixed to the tire cavity surface 13. In other words, the fixed portions 44 are fixed to the tire cavity surface 13 by fixing members 41. The non-fixed portions 45 refer to the portions of the conductor of the loop coil portion 42 that do not have fixed portions 44, i.e., the conductor of the loop coil portion 42 in the range that is not fixed to the tire cavity surface 13 by the fixing members 41.

[0041] In the case of FIG. 2 , the loop coil portion 42 is fixed to the tire cavity surface 13 by a fixing member 41. The fixing member 41 is circular when viewed in the tire width direction. The total tire circumferential length of the multiple fixed portions 44 fixed by the fixing member 41 is shorter than the total tire circumferential length of the multiple non-fixed portions 45. The total tire circumferential length of the multiple fixed portions 44 is preferably 3% to 25% of the tire circumferential length of the loop coil portion 42, and more preferably 5% to 20%. The total tire circumferential length of the multiple fixed portions 44 is the sum of the measured tire circumferential lengths of each fixed portion 44. The tire circumferential length of the loop coil portion 42 is not the length of the conducting wire that constitutes the loop coil portion 42, but the tire circumferential length when installed on the tire cavity surface 13. In other words, even if the number of turns of the loop coil portion 42 is 3, the tire circumferential length of the loop coil portion 42 is the tire circumferential length when installed on the tire inner cavity surface 13, and is approximately the same as the tire circumferential length of the conductor corresponding to the number of turns being 1.

[0042] As shown in FIG. 3 , the fixing member 41 covers the conductive wire that constitutes the loop coil portion 42 and is in contact with the tire cavity surface 13. The fixing member 41 shown in FIG. 3 is interposed between the conductive wire and the tire cavity surface 13. The fixing member 41 is adhered to the surface of the conductive wire and also to the tire cavity surface 13. The hardness of the fixing member 41 is preferably lower than the hardness of the rubber layer exposed to the tire cavity surface 13, which in the case of the tire shown in FIG. 1 is the inner liner 12. Here, the hardness of the rubber refers to the JIS-A hardness measured at room temperature of 23°C using a Type A durometer (Type A) in accordance with JIS K6253. The hardness of the fixing member 41 is preferably 10 or more and 50 or less, and more preferably 20 or more and 45 or less. Examples of materials for the fixing member 41 include various resin materials, SBR, NBR, BR, NR, IIR, silicone rubber, and polyurethane.

[0043] The number n of fixing members 41 preferably satisfies the relationship of the following formula (1) with the tire circumferential length LC of the tread portion D and the tire cross-sectional height SH. The tire cross-sectional height SH is a value measured in a state where the tire is mounted on a rim and normal internal pressure is applied, and in an unloaded state. The tire circumferential length LC is the tire circumferential length of the tread surface 34 at the tire equatorial plane CP.

[0044]

number

[0045] The distance d2 between adjacent fixing members 41 in the tire circumferential direction does not need to be constant, and may differ from one another within a range of ±30% or less of the tire circumferential length of the loop coil portion 42. The distance d2 is the length of the conducting wire between the centers of adjacent fixing members 41.

[0046] The non-fixed portions 45 are not limited to being in contact with the tire cavity surface 13, but also include being out of contact with the tire cavity surface 13, i.e., floating above the tire cavity surface 13. The length of each non-fixed portion 45, i.e., the length d3 of the conductive wire in the non-fixed portion 45, may be longer than the distance between the fixed portions 44 in the tire circumferential direction. The non-fixed portions 45 have a shape that follows the tire circumferential direction. In other words, the non-fixed portions 45 are arc-shaped. The length d3 of each non-fixed portion 45 is longer than the linear distance between adjacent fixed portions 44. The length of each conductive wire in the non-fixed portion 45 may be longer than the linear distance between the fixed portions 44 or the distance along the tire circumferential direction, and may be, for example, 101% to 130% of the distance between the fixed portions 44 in the tire circumferential direction.

[0047] The lead-out portion 43 electrically connects the loop coil portion 42 and the electronic circuit board 46. The lead-out portion 43 shown in FIG. 2 is an extended portion of the conductor that constitutes the loop coil portion 42, and both ends are connected to the electronic circuit board 46 that is arranged outside the loop coil portion 42. The lead-out portion 43 is arranged radially outside the loop coil portion 42. The lead-out portion 43 is a conductor that extends from a base end 43A formed by bending both ends of a conductor wound around the tire center axis toward the radially outside of the loop coil portion 42 to a tip end 43B that contacts an outer edge 46E of the electronic circuit board 46 that contacts the electronic circuit board 46. Although not shown, the electronic circuit board 46 is equipped with, for example, a resonant capacitor for the power receiving coil 40 and a rectifier circuit that converts received AC power to DC.

[0048] The lead-out portion 43 is disposed so as to intersect with the belt-adjacent region MR (FIG. 1). The belt-adjacent region MR is an annular region whose outer edge is an arc (second arc) formed by connecting the intersections of the second perpendicular line VT2 and the tire cavity surface 13 in the tire circumferential direction, and whose inner edge is a position spaced from the second perpendicular line VT2 along the tire cavity surface 13 toward the bead portion A by a length Fx expressed by the following formula (2). The length Fx can be measured by placing a tape measure against the tire cavity surface 13.

[0049] Fx = 0.12 × SH (2) Because the pull-out portion 43 intersects with the belt-adjacent region MR, the loop coil portion 42 and the electronic circuit board 46 are disposed outside the belt-adjacent region MR. In other words, the electronic circuit board 46 is disposed in a portion that overlaps with the belt 20 in the tire radial direction. It is preferable that the only metal member disposed in the belt-adjacent region MR is the conductor that constitutes the pull-out portion 43. Here, examples of metal members include reinforcing materials using metal cords and electronic circuits such as RFID.

[0050] In the belt-adjacent region MR, the entire pull-out portion 43 may be in contact with the tire cavity surface 13. In the belt-adjacent region MR, a portion of the conductor constituting the pull-out portion 43 may not be in contact with the tire cavity surface 13, i.e., may be floating above the tire cavity surface 13. The length of the conductor constituting the pull-out portion 43, i.e., the length from the base end 43A to the tip end 43B, may be longer than the length along the tire cavity surface 13 from the point where the conductor wound around the tire central axis is bent outwardly of the loop coil portion 42 to the outer edge that contacts the electronic circuit board 46.

[0051] The drawn-out portion 43 has one or more second fixed portions 47 fixed to the tire cavity surface 13 by the fixing member 41, and one or more second non-fixed portions 48 that are not fixed to the tire cavity surface 13. The second fixed portions 47 refer to the range of the conductors of the drawn-out portion 43 that are fixed to the tire cavity surface 13 by the fixing member 41. The second non-fixed portions 48 refer to the conductors of the drawn-out portion 43 in a range other than the second fixed portions 47, i.e., the range of the conductors of the drawn-out portion 43 that are not fixed to the tire cavity surface 13 by the fixing member 41. The length of the second fixed portions 47 in the longitudinal direction of the drawn-out portion 43 is shorter than the length of the second non-fixed portions 48 in the longitudinal direction. The total longitudinal length of the drawn-out portions 43 of the second fixed portions 47 is preferably 10% to 50% of the longitudinal length of the second non-fixed portions 48, and more preferably 15% to 45%.

[0052] A part of the pull-out portion 43 is preferably fixed to the tire cavity surface 13 in the belt-adjacent region MR by a second fixing portion 47. That is, the pull-out portion 43 preferably has at least one second fixing portion 47 in the belt-adjacent region MR.

[0053] The tire 10 may have a first additional reinforcing layer 49 that suppresses deformation of the pull-out portion 43. The first additional reinforcing layer 49 is provided further outward in the tire radial direction of the belt 20 at a location on the outer side in the tire width direction where the belt 20 has only one layer. The location on the outer side in the tire width direction where the belt 20 has only one layer has lower rigidity of the tire 10 compared to a location closer to the tire equatorial plane CP where the belt 20 has two layers. By providing the first additional reinforcing layer 49, the tire 10 according to this embodiment suppresses a decrease in rigidity at the location on the outer side in the tire width direction where the belt 20 has only one layer.

[0054] The tire 10 may also have a second additional reinforcing layer 51 extending further outward in the tire width direction from the outer end of the belt 20 in the tire width direction. The second additional reinforcing layer 51 is arranged on the outer side in the tire width direction where the belt 20 is not present. The tire 10 has lower rigidity in the outer portion in the tire width direction where the belt 20 is not present compared to a portion where the belt 20 is two layers and a portion where the belt 20 is only one layer. By providing the second additional reinforcing layer 51, the tire 10 according to this embodiment suppresses a decrease in rigidity in the outer portion in the tire width direction where the belt 20 is not present. The position where the second additional reinforcing layer 51 is provided may overlap with the belt adjacent region MR in the tire radial direction. The second additional reinforcing layer 51 may extend beyond the belt adjacent region MR to the outer side in the tire radial direction. The first additional reinforcing layer 49 and the second additional reinforcing layer 51 may be integral.

[0055] The tire 10 of this embodiment described above is obtained through each of the usual manufacturing steps, i.e., a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and a post-vulcanization inspection step, etc. When manufacturing the tire of this embodiment, convex portions and concave portions corresponding to a predetermined tread pattern are formed on the inner wall of a vulcanization mold, and vulcanization is carried out using this mold.

[0056] The tire 10 may be formed by placing the power receiving coil 40 and the electronic circuit board 46 on a green tire before the vulcanization process and then undergoing the vulcanization process, or the power receiving coil 40 and the electronic circuit board 46 may be fixed to the tire inner cavity surface after vulcanization.

[0057] (Action and effect) A tire 10 mounted on a vehicle (not shown) deforms mainly on the contact patch side when rotating. That is, when the tire 10 is viewed from the outside in the tire width direction, the tire 10, which is a nearly perfect circle, deforms into a shape that conforms to the road surface on the contact patch side. Also, in a tire meridian cross section, the tire 10 deforms so that the sidewall portion B on the contact patch side bulges outward in the tire radial direction. The sidewall portion B has the largest deformation amount on the side of the side region MS closest to the contact patch, i.e., the belt adjacent region MR. The tire cavity surface 13 is integral with the sidewall portion B, and therefore deforms in the same way as the sidewall portion B.

[0058] The power receiving coil 40 is provided on the tire cavity surface 13 and is therefore affected by deformation of the tire cavity surface 13. The conducting wire that makes up the power receiving coil 40 is made of metal, and is therefore more rigid and less likely to deform than the inner liner 12 that makes up the tire cavity surface 13.

[0059] Incidentally, if the entire power receiving coil were fixed to the tire cavity surface, it would deform integrally with the tire cavity surface. The power receiving coil's conducting wires are harder and less likely to deform than the tire rubber, so if the tire deforms significantly, they will not be able to follow the tire deformation and may break.

[0060] The power receiving coil 40 according to this embodiment has a plurality of fixed portions 44 fixed by fixing members 41, and a plurality of non-fixed portions 45 that are not fixed to the tire cavity surface 13. This allows the power receiving coil 40 to deform independently at the non-fixed portions 45 relative to the inner liner 12. In other words, the non-fixed portions 45 are less susceptible to deformation of the tire cavity surface 13. Therefore, the power receiving coil 40 has excellent durability because it has non-fixed portions 45 that are less susceptible to deformation of the inner liner 12.

[0061] The fixing member 41 has a lower hardness than the inner liner 12, and is therefore able to absorb at least a portion of the load received from the inner liner 12. Therefore, the power receiving coil 40 is prevented from being deformed due to deformation of the inner liner 12, and therefore has excellent durability.

[0062] Because the loop coil portion 42 of the power receiving coil 40 is provided within the side region MS of the tire cavity surface 13, the magnetic field is less susceptible to the influence of the bead core 14 and the belt 20, and a decrease in power supply efficiency can be suppressed. Furthermore, because the loop coil portion 42 has a circular shape centered on the tire rotation axis when viewed in the tire width direction, the length of the loop coil portion 42 in the tire radial direction at the sidewall portion B in the tire meridian cross section is short. Therefore, the loop coil portion 42 is less affected by deformation of the sidewall portion B. Furthermore, because the loop coil portion 42 has a circular shape centered on the tire rotation axis, fluctuations in the amount of power received during tire rotation can be suppressed, and a decrease in power supply efficiency can be suppressed.

[0063] Because the loop coil portion 42 is provided in the side region MS, when viewed from the outside in the tire width direction, it deforms in a direction along the road surface together with the tire cavity surface 13. However, the amount of deformation of the loop coil portion 42 at each end of the leading-side and trailing-side in the ground contact patch is smaller than the amount of deformation in the tire width direction in the tire meridian cross section. The tire 10 deforms approximately flat along the road surface in the ground contact patch between the leading-side end and the trailing-side end. Because the non-fixed portion 45 of the loop coil portion 42 has an arc shape along the tire circumferential direction, the longitudinal length of the conductive wire of the non-fixed portion 45 is longer than the linear distance between the fixed portions 44. Therefore, even if the inner liner 12 between the fixed portions 44 deforms approximately flat as viewed in the tire width direction when the tire 10 deforms approximately flat along the road surface in the ground contact patch, the conductive wire of the non-fixed portion 45 can deform linearly without breaking, allowing the loop coil portion 42 to follow the deformation of the inner liner 12.

[0064] Furthermore, because the loop coil portion 42 has a circular shape centered on the tire rotation axis, it is less susceptible to deformation in the tire width direction in the tire meridian cross section, which has a larger deformation amount. Furthermore, by having the number n of fixing members 41 provided on the loop coil portion 42, the tire circumferential length LC of the tread portion, and the tire cross-sectional height SH satisfy the above formula (1), the amount of deformation of the loop coil portion 42 can be appropriately suppressed, and the risk of breakage of the conducting wire that makes up the loop coil portion 42 can be reduced.

[0065] The lead-out portion 43 has an outer edge defined by an arc (second arc) connecting intersections of the second perpendicular line VT2 and the tire cavity surface 13 in the tire circumferential direction, and an inner edge located at a position spaced from the second perpendicular line VT2 along the tire cavity surface 13 toward the bead portion A by a length Fx expressed by the above formula (2) Fx = 0.12 × SH. The lead-out portion 43 deforms in the longitudinal direction of the conductor due to deformation of the tire cavity surface 13 in the tire width direction, as viewed in meridian section. The lead-out portion 43 has a second fixed portion 47 fixed to the tire cavity surface 13 by the fixing member 41 and a second non-fixed portion 48 not fixed to the tire cavity surface 13, and is therefore less susceptible to deformation of the tire cavity surface 13. Therefore, the power receiving coil 40 has the second non-fixed portion 48 that is less susceptible to deformation of the tire cavity surface 13 in the belt adjacent region MR, where deformation is large, and therefore has excellent durability.

[0066] Because the pull-out portion 43 intersects with the belt-adjacent region MR, the loop coil portion 42 and the electronic circuit board 46 are positioned outside the belt-adjacent region MR. That is, the loop coil portion 42 is disposed in the side region MS, which is less susceptible to the influence of the bead core 14 and the belt 20, and the electronic circuit board 46 is positioned closer to the tire equatorial plane CP than the belt-adjacent region MR, thereby suppressing a decrease in power supply efficiency. Because the higher rigidity of the belt 20 suppresses local deformation on the tire equatorial plane CP side than the belt-adjacent region MR, the electronic circuit board 46 is less likely to fall off from the tire cavity surface 13, thereby improving durability.

[0067] The pull-out portion 43 has a second fixing portion 47 in the belt-adjacent region MR. The second fixing portion 47 fixes the conductor in the belt-adjacent region MR to the tire cavity surface 13 and suppresses deformation of the conductor in the belt-adjacent region MR. This allows the pull-out portion 43 to reduce the risk of conductor breakage.

[0068] The tire 10 can suppress a decrease in rigidity in the belt-adjacent region MR of the tire 10 by including at least one of the first additional reinforcing layer 49 and the second additional reinforcing layer 51. Therefore, the tire 10 can suppress deformation of the belt-adjacent region MR and the pull-out portion 43.

[0069] (Variation) The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present invention. In the above-described embodiment, the fixing member 41 is circular when viewed in the tire width direction, but the present invention is not limited to this, and the fixing member 41 may be elliptical, oval, or polygonal, for example.

[0070] In the above embodiment, the loop coil portion 42 is described as being provided in the side region MS, but the present invention is not limited to this. For example, the loop coil portion 42 may be provided on the tire cavity surface 13 corresponding to the tread portion D, as shown in Fig. 4. In this case, the power receiving coil 40 is preferably provided on the tire cavity surface 13 corresponding to the tread portion D, together with the electronic circuit board 46, the lead-out portion 43, and the loop coil portion 42. In this case, the first additional reinforcing layer 49 and the second additional reinforcing layer 51 may be omitted.

[0071] In the above embodiment, a portion of the pull-out portion 43 is fixed to the tire cavity surface 13 of the belt-adjacent region MR by the second fixing portion 47, but the present invention is not limited to this. For example, the pull-out portion 43 may be fixed to the tire cavity surface 13 over the entire range from the outer edge to the inner edge of the intersecting belt-adjacent region MR. That is, the second fixing portion 47 may have a length from the outer edge to the inner edge of the belt-adjacent region MR along the longitudinal direction of the pull-out portion 43. By fixing the pull-out portion 43 to the tire cavity surface 13 over the range from the outer edge to the inner edge of the belt-adjacent region MR by the fixing member 41, durability can be more reliably improved.

[0072] In the above embodiment, the loop coil portion 42 is formed by winding a conductive wire around the tire rotation axis and has one to five turns. However, the present invention is not limited to this. For example, as shown in FIG. 5 , the power receiving coil 62 has multiple loop coil portions 64. In FIG. 5 , the power receiving coil 62 has multiple loop coil portions 64 arranged in the tire circumferential direction (six in FIG. 5 ). Each loop coil portion 64 has a conductive wire wound in a fan shape. Each loop coil portion 64 is fixed to the tire cavity surface 13 by multiple fixing members 41. Because the multiple loop coil portions 64 are independently arranged in the tire circumferential direction, they are less likely to be affected by each other's deformation. Therefore, the power receiving coil 62 can prevent the loop coil portion 64 from peeling off from the tire cavity surface 13. The number of turns of the loop coil portion 64 is preferably one to five. FIG. 6 shows a schematic diagram of a loop coil portion 64 with three turns. The loop coil portion 64 shown in FIG. 6 is wound three times, and the ends of the conductive wire do not cross each other. The lead-out portions 43 are portions where both ends of the conductive wire that constitutes the loop coil portion 64 are led out to the outside of the loop coil portion 64 .

[0073] In the power receiving coil 62 shown in FIG. 5, it is also preferable that the number n of the fixing members 41 satisfies the relationship of the above formula (1) with the tire circumferential length LC of the tread portion D and the tire cross-sectional height SH.

[0074] In the above embodiment, the fixing member 41 covers the conductor that constitutes the power receiving coil 40 and is interposed between the conductor and the tire cavity surface 13, but the present invention is not limited to this. For example, as shown in FIG. 7(A), the fixing member 41 does not have to be interposed between the conductor 66 and the tire cavity surface 13. A portion of the conductor 66 shown in FIG. 7(A) is buried in the inner liner 12, and the surface of the conductor 66 on the side opposite the inner liner 12 is covered with the fixing member 41. In the structure shown in FIG. 7(A), the conductor 66 is placed in a green tire before vulcanization, the fixing member 41 is provided in an appropriate position, and the tire 10 is obtained by vulcanizing the tire in a state in which the conductor 66 is temporarily fixed to the tire cavity surface 13.

[0075] The fixing member 41 is not limited to a single-layer structure made of one type of material, but may also have a two-layer structure including a first layer and a second layer made of two types of material. The first and second layers are not limited to being made of different types of materials, but may be made of the same material but with different hardnesses. It is preferable that the rubber hardness of at least one of the first and second layers is lower than that of the inner liner 12. For example, the fixing member 41 shown in FIG. 7(B) includes a first layer 41A that contacts the inner liner 12 and a second layer 41B that contacts the surface of the first layer 41A. The conductive wire 66 is covered by the second layer 41B. In the fixing member 41 shown in FIG. 7(C), the first layer 41A extends from approximately the center of the conductive wire 66 to the surface of the inner liner 12, and the second layer 41B extends from the surface of the first layer 41A to the area covering the surface of the conductive wire 66. That is, a portion of the conductive wire 66 is buried in the first layer 41A, and the surface of the conductive wire 66 on the side opposite the first layer 41A is covered with the second layer 41B. In the fixing member 41 shown in FIG. 7(D), a portion of the first layer 41A on the inner liner 12 side is buried in the inner liner 12. A portion of the conductive wire 66 on the inner liner 12 side is buried in the first layer 41A. The surface of the conductive wire 66 on the side opposite the first layer 41A is covered with the second layer 41B. In the fixing member 41 shown in FIG. 7(D), the first layer 41A is placed on the tire cavity surface 13 of a green tire before vulcanization, and then the power receiving coil 40 and the second layer 41B are placed in that order, and the tire 10 is obtained by vulcanizing the tire. 2. Wireless Power Supply System 8 is a diagram showing a tire 10 (a portion on one side in the tire width direction with reference to the tire equatorial plane CP in a tire meridian cross section of the tire on the non-ground-contact side) provided with a power transmitting coil 52 and a power receiving coil 40 in a wireless power supply system 50 according to this embodiment. Note that Fig. 8 shows the tire portion on the opposite side from the ground contact surface when the tire is mounted on a rim, pressurized to a normal internal pressure, and subjected to a load of 80% of the normal load (the same applies hereinafter to the invention of a wireless power supply system).

[0076] The power transmission coil 52 shown in the figure forms a resonant circuit using a capacitor and a coil, and is attached, for example, to the tire-side surface of a knuckle or hub carrier, which are components of a steering axle of a vehicle (not shown), or to one of the components that make up the strut structure.

[0077] Next, the power receiving coil 40 shown in Fig. 8 has the same configuration as the power receiving coil shown in Fig. 1, and a resonant circuit is formed by a capacitor and a coil. Note that the tire 10 shown in Fig. 8 is a tire of the basic configuration 1 related to the tire 10 described above, and a tire in which at least one of additional configurations 2 to 8 is added to the basic configuration 1, and its actions, functions, etc. are as described above.

[0078] Under these assumptions, the wireless power feeding system 50 according to this embodiment is a magnetic field resonance type wireless power feeding system that uses an AC magnetic field, and as shown in Fig. 8, power is fed to the power transmitting coil 52, and the power is transmitted to the power receiving coil 40 by the AC magnetic field. With this wireless power feeding system 50, as described above, it is possible to improve the power feeding efficiency.

[0079] Here, it is preferable to transmit power of 0.1 to 15 W at a frequency of 1 to 20 MHz to drive sensors and associated electrical circuits installed inside the tire 10. More preferably, AC power with a frequency of 6.78 to 13.56 MHz is applied to the power transmission coil 52.

[0080] Furthermore, the shortest distance between the power transmitting coil 52 and the power receiving coil 40 (hereinafter sometimes referred to as the "transmission gap G") is preferably 10 mm or more and 80 mm or less. Here, the transmission gap G is a value measured when the tire 10 is mounted on a rim, pressurized to the normal internal pressure, mounted on a vehicle, and stopped on flat ground. The transmission gap G is the shortest distance between the power transmitting coil 52 and the power receiving coil 40, i.e., in FIG. 8, it refers to the distance between the innermost position of the power transmitting coil 52 in the tire width direction and the outermost position of the power receiving coil 40 in the tire width direction.

[0081] Setting the transmission gap G to 10 mm or more can prevent excessive fluctuations in received power caused by fluctuations in the relative positions of the power transmitting coil 52 and the power receiving coil 40 (shown in FIG. 8) in the direction of power transmission. This simplifies the circuit configuration connected to the power receiving coil 40, making it possible to easily supply stable power to an electronic device. The fluctuations in received power depend on fluctuations in the relative positions between the two coils 52, 40 caused by slight expansion of the tire 10 due to centrifugal force while the tire 10 is rotating. Specifically, as the tire rotation speed increases, the tire 10 expands in the tire radial direction, causing the power receiving coil 40 to move radially outward (toward the top of FIG. 8), while the position of the power transmitting coil 52 remains unchanged, resulting in a change in the relative positions between the two coils 52, 40.

[0082] In contrast to this, by setting the transmission gap G to 80 mm or less, the strength of the magnetic field generated between the two coils 52, 40 does not become excessively small, and power can be efficiently supplied by the AC magnetic field.

[0083] The transmission gap G is more preferably 12 mm or more and 75 mm or less, and most preferably 15 mm or more and 70 mm or less.

[0084] By adopting the above-described range of transmission gap G, power range, and frequency band, not only can the temperature rise of the power receiving coil 40 be suppressed, but also an increase in the number of coil turns (and thus an increase in coil weight) is unnecessary, so that the rolling resistance of the tire is not increased, power can be fed efficiently, and excellent power feeding efficiency can be achieved. Furthermore, in particular, according to the above-described range of 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.

[0085] 8, the power transmitting coil 52 is disposed so as to extend in the tire radial direction, but this embodiment is not limited to such an arrangement. That is, as long as the transmission gap G described above is within a predetermined range, the extension direction of the power transmitting coil 52 may be inclined with respect to the tire radial direction.

[0086] When the power receiving coil 40 is provided on the inside of the vehicle mounting surface, the power transmitting coil 52 can be installed inside the wheel house, thereby easily keeping the transmission gap G within the above range.

[0087] In a tire meridian cross section, it is preferable that at least a portion of the power receiving coil 40 be located within a power supply region that extends in the winding axis direction of the power transmitting coil 52 across both longitudinal ends of the power transmitting coil 52.

[0088] Here, the positional relationship between the power receiving coil 40 and the power transmitting coil 52 is measured with the tire 10 mounted on a rim, pressurized to the normal internal pressure, attached to a vehicle, and stopped on flat ground. More preferably, the power transmitting coil 52 is arranged so that the power transmitting coil radial direction area defined by the length between both ends of the tire in the radial direction overlaps at least a part of the power receiving coil radial direction area defined by the length between both ends of the tire in the radial direction. Such an arrangement can achieve higher power transfer efficiency.

[0089] 9(A) and 9(B) is disposed on the outer side in the tire width direction, at a position corresponding to a partial region in the tire circumferential direction. The power receiving coil 40 provided on the tire cavity surface extends around the entire tire circumferential direction. At least a portion of the power receiving coil 40 is provided in a region obtained by projecting the power transmitting coil radial direction region onto the tire cavity surface, i.e., a region between points where imaginary lines extending from the tire radially outer end and the tire radially inner end of the power transmitting coil 52 to the tire cavity surface and parallel to the winding axis of the power transmitting coil 52 intersect with the tire cavity surface. For the power receiving coil 40 provided on the tire cavity surface, it is preferable that a portion of the tire radial direction of the power receiving coil 40 is included in the region obtained by projecting the power transmitting coil radial direction region, and it is more preferable that the entire tire radial direction of the power receiving coil 40 is included in the region obtained by projecting the power transmitting coil radial direction region.

[0090] In the wireless power supply system 50 according to this embodiment, the power transmission coil 52 is attached to a knuckle or hub carrier (located on the outer side of the sidewall portion B in the tire width direction), which is a part of the steering axle of the vehicle, or to the tire-side surface of one of the parts constituting the strut structure. Therefore, when examining the power supply efficiency taking into account the shape of the tire 10, particularly the sidewall portion B, it is desirable that the direction of the magnetic field lines penetrating the tire at the sidewall portion B, and therefore the power supply direction Dp, be approximately in the tire width direction, as shown in Figures 9(A) and 9(B).

[0091] Based on this knowledge, when the power supply direction Dp is set to be substantially in the tire width direction as shown in Figures 9(A) and (B), power supply can be performed more efficiently, and ultimately excellent power supply efficiency can be achieved.

[0092] Furthermore, in the example shown in Figures 9(B) and (C), the constituent surfaces (planes normal to the winding axes of each coil in Figures 9(B) and (C)) of the transmitting coil 52 and the receiving coil 40 are parallel to each other, so power can be supplied more efficiently than in the example shown in Figures 9(A) and (D), and superior transmission efficiency can be achieved.

[0093] 9(A) and 9(D), the constituent surfaces of the power transmitting coil 52 and the power receiving coil 40 do not need to be parallel to each other. This is because, when the magnetic field generated by the power transmitting coil 52 interlinks with the power receiving coil 40, an electromotive force is generated by the AC magnetic field, and there are no restrictions on the relative orientation of the above-mentioned surfaces.

[0094] The power transmission coil 52 is preferably installed within a range of 60° on both sides in the tire circumferential direction, centered on an imaginary line extending vertically upward from the center of the tire.

[0095] Typically, when the tire 10 rolls, the power receiving coil 40 deforms in accordance with the deformation of the tire 10 at the contact portion of the tire 10, whereas the power receiving coil 40 in a portion of the tire 10 away from the contact portion (the upper portion of the tire 10 in FIG. 10 ) hardly deforms in accordance with the tire deformation. For this reason, by installing the power transmitting coil 52 located on the outside of the tire 10 near the upper portion of the tire away from the contact portion of the tire 10 (a tire circumferential range R of 60° on both sides of an imaginary line extending vertically upward from the tire center O), it is possible to suppress fluctuations in the transmission gap G described above when the tire rolls, thereby enabling more efficient power transfer and ultimately achieving even better power transfer efficiency. Note that the example shown in FIG. 10 is an example in which the power transmitting coil 52 is attached to a wheel well 54, and the tire circumferential range R described above is applied within the wheel well 54.

[0096] It is more preferable that the power transmission coil 52 be installed within a circumferential range of 55° on either side of an imaginary line extending vertically upward from the tire center O, and it is extremely preferable that the power transmission coil 52 be installed within a circumferential range of 50° on either side of the imaginary line.

[0097] Furthermore, the shape of the power transmission coil 52 is not particularly limited, but when the power transmission coil 52 is installed, for example, inside a wheelhouse, it is preferable to use a so-called spiral coil, which allows the overall thickness to be reduced.

[0098] Although the case where the power transmitting coil unit 56 includes the case 58 has been described, the present invention is not limited to this. The power transmitting coil unit 56 may have a power transmitting coil 52 and a resin film that covers the power transmitting coil 52. In this case, the power transmitting side surface refers to the surface of the resin film that faces the power receiving coil 40. The power transmitting coil unit 56 may also be composed of the power transmitting coil 52. In this case, the power transmitting side surface refers to the surface of the power transmitting coil 52 that faces the power receiving coil 40.

[0099] It is preferable that the angle β that the power transmission side surface 60 of the power transmission coil unit 56 including the power transmission coil 52 makes with the tire radial direction as viewed from the tire meridian cross section is in the range of 70° toward the tire 10 and 30° away from the tire 10, with the tire radial inner end 57 of the power transmission coil unit 56 as the center.

[0100] As described above, the power transmitting coil unit 56 may have a power transmitting coil 52 and a case 58 that houses the power transmitting coil 52. As shown in Fig. 11 , the case 58 has a power transmitting side surface 60, and the angle formed by the power transmitting side surface 60, which is centered on the lower end of the power transmitting coil unit 56 in the tire radial direction, and the tire radial direction is defined as β. The angle β is in the range of 70° toward the tire 10 and 30° away from the tire radial direction.

[0101] The power transmission side surface 60 of the power transmission coil unit 56 facing the power receiving coil 40 is less likely to get wet because the angle β between the power transmission side surface 60 and the tire circumferential direction when viewed from the tire meridian cross section is within the above range, making it easy to install the power transmission coil unit 56 at an angle and position that allows efficient power supply to the power receiving coil 40. <Other forms of tires and wireless power supply systems> The tire and the wireless power supply system according to the present invention have been described above. Other matters relating to the tire and the wireless power supply system according to the present invention will be listed below.

[0102] The carbon content of the inner liner 12, which is a component of the tire 10, is preferably 45 to 75 parts by mass (mass parts when the rubber is 100, the same applies below), the carbon content of the side tread is 25 to 65 parts by mass, the carbon content of the bead filler 16 is 40 to 80 parts by mass, and the carbon content of the covering rubber of the carcass 18 is 35 to 70 parts by mass. By adopting these respective content amounts, it is possible to achieve the desired rubber properties in each rubber layer. Note that, while the thermal conductivity of rubber is usually determined by the type of polymer and compounding ingredients, adjusting the carbon content is most preferable because it makes it easy to change the heat dissipation properties, thereby ensuring durability while maintaining the rubber properties required for a tire.

[0103] In the wireless power transfer system 50 shown in Fig. 8, the power receiving coil 40 is preferably provided in the tire cavity of the sidewall portion B of the tire 10 with its constituent surface facing in the tire width direction. As described above, when the power transfer direction by the power transmitting coil 52 is set to be substantially the tire width direction, as shown in Figs. 9(A) and 9(B), by providing the power receiving coil 40 with its constituent surface facing in the tire width direction, the power transfer surface of the power transmitting coil 52 and the constituent surface of the power receiving coil 40 become parallel. This allows for more efficient power transfer, and ultimately achieves excellent power transfer efficiency.

[0104] Figure 12 is a diagram showing arrangements of the receiving coil 40, where (A) to (F) are examples showing a receiving coil 40 consisting of 2, 3, 4, 5, 6, and 8 sets of loop coil sections 40a, respectively, (G) is an example in which multiple loop coil sections 40a are stacked in the tire radial direction, and (H) is an example in which some of the multiple loop coil sections 40a extend at an angle relative to the tire radial direction.

[0105] As shown in Figures 12(A) to 12(H), the power receiving coil 40 may be formed from multiple loop coil portions 40a. On the tire cavity surface where the power receiving coil 40 is provided, the tire 10 repeatedly deforms and releases while the tire 10 is rolling. If one power receiving coil 40 is provided around the entire circumference of the tire 10, the power receiving coil 40 will have portions that are distorted by deformation while the tire 10 is rolling (near the contact area of ​​the tire 10) and portions that are not deformed (upper part of the tire 10), making it easier for the power receiving coil 40 to peel off from the tire cavity surface. Therefore, by dividing the circumference of the tire into multiple regions and arranging loop coil portions 40a in each of the divided regions, it is possible to prevent the power receiving coil 40 from peeling off from the tire inner circumferential surface. [Example]

[0106] Below, we will explain the results of manufacturing a tire corresponding to the invention defined in the claims of this application and evaluating the durability of the power receiving coil.

[0107] The tire size was set to 245 / 40R19 (specified by JATMA), and the tire shown in Fig. 1 was produced. The conditions for the tires 10 of Examples 1 to 5 are as shown in Table 1 below. "(LC × SH) / n" and "Fx / SH" in Table 1 conform to the definitions described in this specification.

[0108] The tires of Examples 1 to 3 thus produced were mounted on wheels with a rim size of 19×8.5J, and the durability of the power receiving coil was evaluated by the method described below.

[0109] (durability) A running test was started using a drum testing machine under conditions of an air pressure of 220 kPa, a load of 6.6 kN, and an initial speed of 150 km / h. The speed was increased by 5 km / h every 10 minutes, and the speed at which the receiving coil broke or fell off from the inside of the tire was indexed.

[0110] [Table 1]

[0111] (result) Comparing Examples 1 to 4 with Reference Examples 1 and 2, it was found that the durability of the receiving coil is improved by setting "(LC×SH) / n" to 4000 or more and 33000 or less. Comparing Example 3 with Example 4, it was found that the durability is further improved by setting "Fx / SH" to 0.12. [Explanation of symbols]

[0112] 10 Tires 12 Inner liner 13 Tire cavity surface 14 Bead core 16 Bead Filler 18 Carcass 18a Main body 18b Folded part 20 Belt 20a belt layer 20b Belt layer 26 Side tread 30 Cap Tread 34 Tread surface 40 receiving coil 40a Loop coil section 41 Fixing member 41A 1st layer 41B 2nd layer 42 Loop coil section 43 Drawer section 43A Proximal end 43B Tip 44 Fixed part 45 Non-fixed part 46 Electronic Circuit Board 46E outer edge 47 Second fixed part 48 2nd non-fixed part 49 First additional reinforcement layer 50 Wireless Power Supply System 51 Second additional reinforcement layer 52 Transmission coil 54 Wheelhouse 56 Power transmission coil unit 58 cases 60 Power transmission surface 62 receiving coil 64 Loop coil section 66 Conductor A Bead part B Sidewall C Shoulder part D Tread

Claims

1. A tire comprising: a tread portion provided with a belt; bead portions provided with annular bead cores; a pair of sidewall portions provided between the tread portion and the bead portions; a power receiving coil formed of a conductor that receives power supplied by an AC magnetic field from outside the tire; and a plurality of fixing members that fix the power receiving coil to a tire inner cavity surface, the power receiving coil has, in the longitudinal direction of the conductor, a fixed portion fixed to the tire cavity surface by the fixing member, and a non-fixed portion not fixed to the tire cavity surface.

2. the power receiving coil has a loop coil portion made of a loop coil, the loop coil portion is disposed in the side region, 2. The tire according to claim 1, wherein the side region is a region in a meridian cross section of the tire between a first perpendicular line drawn from an outer end of the bead core in the tire radial direction to a tire cavity surface in a normal direction to the tire cavity surface, and a second perpendicular line drawn from an outer end of the belt in the tire width direction to the tire cavity surface in a normal direction to the tire cavity surface.

3. The tire according to claim 1 , wherein the fixing member has a hardness lower than that of the rubber layer exposed to the tire cavity.

4. The tire according to claim 1 , wherein the number n of the fixing members, the tire circumferential length LC of the tread portion, and the tire cross-sectional height SH satisfy the following formula (1): [Equation 1]

5. 2. The tire according to claim 1, wherein the power receiving coil has a loop coil portion consisting of a loop coil with one turn centered on the tire rotation axis, and the loop coil portion is installed on a tire inner cavity surface corresponding to the sidewall portion.

6. the power receiving coil has a loop coil portion made of a loop coil and a lead-out portion formed of a conductor that connects the loop coil portion to an electronic circuit board, 3. The tire according to claim 2, wherein the lead-out portion has, in a longitudinal direction of the conductor, a second fixed portion fixed to the tire cavity surface by the fixing member and a second non-fixed portion not fixed to the tire cavity surface.

7. The pull-out portion and the belt adjacent region intersect, 7. The tire according to claim 6, wherein, when a tire cross-sectional height is SH, the belt-adjacent region is an annular region whose outer edge is a position where a second perpendicular line drawn from a side end of the belt in the tire width direction in a direction normal to the tire cavity surface intersects with the tire cavity surface, and whose inner edge is a position spaced apart from the second perpendicular line along the tire cavity surface toward the bead portion by a length Fx expressed by the following formula (2): Fx=0.12×SH...(2)

8. The tire according to claim 7 , wherein the second fixing portion is located in the belt adjacent region.

9. The tire according to claim 7 , wherein the fixing member fixes the pull-out portion to the tire cavity surface in a range from an outer edge to an inner edge of the belt-adjacent region.

10. The tire according to claim 7 , further comprising a first additional reinforcing layer for suppressing deformation of the pull-out portion, on an outer side in the tire width direction, at a location where only one layer of the belt is formed.

11. The tire according to claim 7 , further comprising a second additional reinforcing layer on an outer side of the belt in the tire width direction, the second additional reinforcing layer suppressing deformation of the pull-out portion.

12. The tire according to any one of claims 1 to 11, mounted on a regular rim.

13. 3. A wireless power supply system that supplies AC power to a power transmitting coil that forms a resonant circuit with a capacitor and a coil, and transmits the power to the power receiving coil that also forms a resonant circuit with a capacitor and a coil, the wireless power supply system including the tire according to claim 1 or 2.

14. 14. The wireless power transfer system according to claim 13, wherein at least a portion of the power receiving coil is located within a power transfer region that extends in a winding axis direction of the power transmitting coil across both longitudinal end portions of the power transmitting coil in a tire meridian cross section.

15. 14. The wireless power transfer system according to claim 13, wherein a power transmitting side surface of the power transmitting coil unit including the power transmitting coil that faces the power receiving coil forms an angle with the tire radial direction as viewed from the tire meridian cross section within a range of 70° toward a side closer to the tire and 30° toward a side away from the tire, with an inner end of the power transmitting coil unit in the tire radial direction as a center.

16. The wireless power supply system according to claim 13 , wherein the power transmitting coils are installed within a range of 60° on both sides in the tire circumferential direction about an imaginary line extending vertically upward from the center of the tire.

Images