WO2024010019A1 - Tire and power feed system - Google Patents

Abstract

This tire comprises a power reception coil that generates electric power upon reception of an AC magnetic field from the outside of the tire. The power reception coil is provided to a side part, between a tread part and a bead part, at the inner side surface facing a tire hollow region of the tire, and generates AC power upon reception of an AC magnetic field that has passed through said side part. The power reception coil has a circular shape and extends along the inner side surface so as to go around in the tire circumferential direction. When the thickness of the side part at the location, of the inner side surface, where the power reception coil is disposed is defined as Ts and the minimum thickness of the side part in the tire radial thicknesses is defined as Tmin, the ratio Ts/Tmin is 1.0-5.5.

Description

Tires and power supply system

The present invention relates to a power supply system for supplying power to a tire and an electronic device provided on the tire.

Technology has been proposed to monitor the condition of tires by incorporating electronic devices such as sensors into tires. For example, in order to monitor the air pressure of a pneumatic tire, a pressure sensor and a transmitting device are provided in the tire cavity area, and an internal pressure alarm system that wirelessly transmits the pressure monitoring result by the pressure sensor from the transmitting device to a receiving device on the vehicle side; Alternatively, an acceleration sensor may be provided on the inner peripheral surface of the tread within the tire cavity, and the results of monitoring the deformation behavior of the tread during tire rolling may be transmitted to the vehicle from a transmitting device provided within the tire cavity. Examples include a tire deformation behavior measurement system that wirelessly transmits data to a receiving device on the side.

Power is required to drive such a sensor and transmitter, and this power is supplied, for example, from a battery built into the transmitter. However, since the power capacity supplied by this battery is limited, it is not possible to drive the sensor and transmitter semi-permanently, and the pneumatic tire and wheel assembled on the wheel must be separated to reduce wear and tear within the tire cavity. A complicated process is required to replace the old battery.

On the other hand, a technique is known that provides a tire that includes an electric circuit and is capable of stably supplying power to the electric circuit, and a power supply structure for the tire (Patent Document 1).
In the above technology, the tires of the automobile are provided with an electric circuit that receives electric power and is driven, and a secondary coil that is connected to the electric circuit, and the vehicle body of the automobile is provided with an inverter that is connected to the power supply device of the vehicle. A primary coil is disposed in a portion of the vehicle body that faces the tires, and is excited by an inverter.

Japanese Patent Application Publication No. 2000-255229

In the above technology, a plurality of secondary coils provided in a tire cavity region are embedded adjacent to each other over the entire inner peripheral surface of the side wall of the tire (FIG. 5 of Patent Document 1).
In the above technology, the transmission efficiency is highest when each of the secondary coils is positioned facing the primary coil. As the tire rotates, the position where the primary coil and the secondary coil face each other changes, causing the transmitted power to fluctuate. Therefore, depending on the rotational position of the tire relative to the primary coil when the vehicle is stopped or running at low speed, the transmitted power may become low and sufficient power may not be supplied to the transmitter and sensor.

The present invention aims to provide a tire that can improve transmission efficiency while suppressing fluctuations in transmitted power when power is supplied to electronic devices provided in the tire, and a power supply system applied to this tire. purpose.

The present disclosure includes the following aspects.
Aspect [1]
A tire equipped with a power receiving coil that generates electric power by receiving an alternating magnetic field from outside the tire,
A power receiving coil is provided on the inner surface of the side of the side portion between the tread portion and the bead portion facing the tire cavity region of the tire, and generates AC power by receiving an alternating current magnetic field transmitted through the side portion. Prepare,
The power receiving coil is a circular coil that extends around the inner surface of the side in a circumferential direction of the tire,
The thickness of the side portion at the position of the inner surface of the side where the power receiving coil is provided is Ts [mm], and the minimum thickness of the side portion in the tire radial direction is Tmin [mm]. A tire characterized in that: the ratio Ts/Tmin is 1.0 to 5.5.

Aspect [2]
When the power receiving coil is referred to as a first power receiving coil, the power receiving coil further includes a second power receiving coil that is provided on the inner surface of the side and generates an alternating current magnetic field by receiving an alternating magnetic field transmitted through the side part,
The tire according to aspect [1], wherein the second power receiving coil is a circular coil that extends along the inner surface of the side and concentrically with the first power receiving coil in a circumferential direction of the tire.

Aspect [3]
The first power receiving coil and the second power receiving coil extend so that both ends of the first power receiving coil and the second power receiving coil deviate from the tire circumferential direction so that the power receiving coil is interrupted in the tire circumferential direction. having a discontinuity formed;
The tire according to aspect [2], wherein the angle formed by the discontinuous portion of the first power receiving coil and the discontinuous portion of the second power receiving coil in the tire circumferential direction is 4 degrees or more.

Aspect [4]
Regarding the height along the tire radial direction with reference to the inner end of the tire radial direction of the bead portion, the cross-sectional height of the tire is Sh [mm], and the thickness of the side portion is Tmin. The height of the position on the surface is Ht [mm], the height of the position on the side inner surface where the first power receiving coil is provided is H1 [mm], and the height of the position on the side inner surface where the first power receiving coil is provided is H1 [mm]. When the height of the position on the side inner surface is H2 [mm] and the flatness ratio of the tire is P x 100 [%],
Ht-Sh×P/4≦H1≦Ht+Sh×P/4, and Ht-Sh×P/4≦H2≦Ht+Sh×P/4,
The tire according to aspect [2] or [3], which satisfies at least one of the following.

Aspect [5]
A power supply system that wirelessly transmits power from a power transmission unit to a power reception unit provided on a tire to supply power to an electronic device connected to the power reception unit,
The power transmission unit includes a power transmission coil that is provided at a base that does not rotate with respect to the tire and generates an alternating current magnetic field,
The power receiving unit is provided on an inner surface of a side portion of the tire between a tread portion and a bead portion of the tire facing a tire cavity region, and the power receiving unit is configured to receive power generated from the power transmission coil and transmitted through the side portion. comprising a power receiving coil that generates AC power by receiving the AC magnetic field,
The electronic device is driven by receiving power converted from the AC power to DC power in the power receiving unit,
The power transmitting coil is provided at the base and is disposed on a side opposite to the power receiving coil with respect to the side part,
The power receiving coil is a circular coil that extends around the inner surface of the side in a circumferential direction of the tire,
The thickness of the side portion at the position in the tire radial direction of the side inner surface where the power receiving coil is provided is Ts [mm], and the minimum thickness of the side portion in the tire radial direction is Tmin [mm]. mm], the ratio Ts/Tmin is 1.0 to 5.5.

Aspect [6]
The power transmission coil has a planar power transmission area arranged to face the side part,
The power transmission coil has an arc-shaped curvature portion that extends according to a predetermined curvature in the plane of the power transmission region,
The power feeding system according to aspect [5], wherein the curvature portion forms a part of a section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil when viewed in the tire width direction.

Aspect [7]
The power receiving coil has a discontinuous portion formed such that the power receiving coil is interrupted in the tire circumferential direction by extending both ends of the power receiving coil deviating from the tire circumferential direction,
Aspect [1] wherein the ratio d/L of the distance d [mm] between the both ends of the discontinuous part in the tire circumferential direction to the length L [mm] of the curvature part in the tire circumferential direction is 1/3 or less. 6].

Aspect [8]
When the power receiving coil is referred to as a first power receiving coil, the power receiving unit further includes a second power receiving coil that is provided on the inner surface of the side and generates an alternating current magnetic field by receiving an alternating magnetic field transmitted through the side part,
According to aspect [6] or [7], the second power receiving coil is a circular coil that extends along the inner surface of the side and concentrically with the first power receiving coil in a circumferential direction of the tire. power supply system.

Aspect [9]
The distance R [mm] between the first power receiving coil and the second power receiving coil in the tire radial direction with respect to the average value G [mm] of the distance between the power transmission region and each of the first power receiving coil and the second power receiving coil. The power supply system according to aspect [8] or [9], wherein the ratio R/G is 0.1 to 1.2.

Aspect [10]
In a cross section passing through the curvature part along the tire radial direction, a first radial region where the curvature part is located, the first power receiving coil located on the side opposite to the curvature part with respect to the side part, and The power feeding system according to any one of aspects [8] to [10], wherein the second radial region whose ends are the positions of the second power receiving coils in the tire radial direction is not separated in the tire radial direction. .

Aspect [11]
The power transmission unit is a magnetic body disposed on a side opposite to the side portion with respect to the power transmission coil, and has a relative magnetic permeability of 30 to 300 at a frequency of an alternating current magnetic field generated by the power transmission coil. The power feeding system according to any one of aspects [8] to [10], further comprising:

Aspect [12]
The magnetic body is arranged on a side opposite to the side portion with respect to the power transmission coil, with a distance h [mm] from the power transmission coil,
The ratio h/G of the interval h to the average value G [mm] of the distance between the power transmission region and each of the first power receiving coil and the second power receiving coil is 0.01 to 0.5, [ 11].

Aspect [13]
ratio Ts1 of the thickness Ts1 [mm] of the side portion at the position of the inner surface of the side where the first power receiving coil is provided to the distance G1 [mm] in the tire width direction between the power transmitting coil and the first power receiving coil; /G1, and the thickness Ts2 of the side portion at the position of the side inner surface where the second power receiving coil is provided with respect to the distance G2 [mm] in the tire width direction between the power transmission region and the second power receiving coil. The power feeding system according to any one of aspects [8] to [12], wherein at least one of the ratio Ts2/G2 of [mm] is 0.1 to 0.7.

Aspect [14]
The power transmitting coil and the power receiving coil each include a single conductive wire made of a single wire,
The power supply system according to any one of aspects [5] to [13], wherein the diameter of the conductor of the conductor in the power transmission coil is larger than the diameter of the conductor of the conductor in the power reception coil.

Aspect [15]
From aspect [5], the power transmission coil is located within an angular range of 45 degrees on each side of a line extending vertically upward from the central axis of rotation of the tire in the tire circumferential direction, when viewed in the tire width direction. 14]. The power supply system according to any one of [14].

According to the tire and power supply system described above, it is possible to increase transmission efficiency while suppressing fluctuations in power when power is supplied to electronic devices provided within the tire.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a cross section of a tire and a power supply system according to an embodiment. FIG. 3 is a plan view of a power receiving coil. FIG. 3 is a cross-sectional view illustrating the arrangement of power receiving coils. It is a plan view of a power transmission coil. (a) is a diagram showing the overlapping of a power transmitting coil and a power receiving coil as seen in the tire width direction, and (b) is a partially enlarged view of (a). (a) is a diagram showing an overlap between a power transmitting coil and a discontinuous portion of a power receiving coil when viewed in the tire width direction, and (b) is a partially enlarged view of (a). It is a figure explaining arrangement of a power transmission coil and a power reception coil. FIG. 3 is a diagram illustrating the arrangement of two power receiving coils. (a) to (d) are cross-sectional views illustrating the positional relationship between the power transmitting coil and the power receiving coil along the tire radial direction. It is a figure explaining a magnetic body. It is a figure explaining arrangement of a magnetic body, a power transmission coil, and a power reception coil. FIG. 3 is a diagram showing an example of a cross section of a coil. FIG. 3 is a cross-sectional view illustrating the relationship between the distance between a power transmitting coil and a power receiving coil, and the thickness of a side portion. FIG. 2 is a cross-sectional view illustrating the relationship between the height position of a power receiving coil and the aspect ratio of a tire. FIG. 2 is a diagram illustrating an angular range around the rotation center axis of the tire in which a power transmission coil is arranged.

Hereinafter, a tire according to one embodiment and a power feeding system for supplying power to an electronic device provided on the tire will be described with reference to the drawings. The tire of the present invention is preferably a pneumatic tire, and in the following description, a pneumatic tire will be used as an example. The gas filled in the hollow region surrounded by the pneumatic tire and the rim is not limited to air, and may be an inert gas such as nitrogen or other gases.

FIG. 1 is a diagram showing an example of a cross section of a pneumatic tire and a power supply system including the pneumatic tire. A pneumatic tire (hereinafter also simply referred to as a tire) 10 shown in FIG. 1 includes a pair of bead cores 12, a carcass ply layer 14, and a belt layer 16 as skeleton parts. The tire 10 is assembled to a wheel 11 (see FIG. 3). In FIG. 3, a part of the wheel 11 (rim bottom surface, rim flange) is shown.

The bead core 12 is an annular member formed by winding a steel bead wire in multiple stages in the tire circumferential direction. A bead portion B is formed by the bead core 12, the rim cushion rubber 46, the carcass ply layer 14, and the inner liner rubber 48 arranged around the bead core 12. There is one bead portion B on each side in the tire width direction.
The carcass ply layer 14 is a member made of an organic fiber cord that has a toroidal shape by being wound around each of the bead cores 12 and folded back. In the carcass ply layer 14, organic fiber cords are provided so as to extend in the tire radial direction or the tire width direction. Although the tire 10 shown in FIG. 1 is composed of one carcass ply layer 14, a plurality of carcass ply layers may have a toroidal shape.
The belt layer 16 is provided on the outside of the carcass ply layer 14 in the tire radial direction, and is composed of a steel belt cord. The belt layer 16 is composed of two laminated belts, and the steel cords have different inclination directions with respect to the tire circumferential direction to form an intersecting layer.
Tread rubber 40, side rubber 42, bead filler rubber 44, rim cushion rubber 46, and inner liner rubber 48 are provided around these skeleton parts. The tread portion T is formed by the tread rubber 40, the belt layer 16, the carcass ply layer 14, and the inner liner rubber 48 that are laminated on the tread rubber 40. On the outer side of the bead core 12 in the tire radial direction, side rubber 42, bead filler rubber 44, rim cushion rubber 46, carcass ply layer 14, and inner liner rubber 48 are curved convexly outward in the tire width direction. In the example shown in FIG. 1, the side portion S is a portion between the tread portion T and the bead portion B, and is formed of side rubber 42, rim cushion rubber 46, carcass ply layer 14, and inner liner rubber 48. The side portions S are located between the tread portion T and the bead portion B, and there is one on each side in the tire width direction. Note that the configuration of the rubber of the side portion S is not limited to the configuration described above, and in addition to the side rubber 42, rim cushion rubber 46, and inner liner rubber 48, the rubber configuration of the side portion S may further include rubber such as an auxiliary filler, a run flat liner, and a bead filler. There is. The auxiliary filler is a rubber that reinforces the side portion of the side portion S on the side of the bead portion B. For example, the auxiliary filler is placed between the carcass ply layer and the rim cushion rubber or the side rubber, and has a harder rubber than the side rubber. It is a high quality rubber. A run-flat liner is a rubber that reinforces the side part of a run-flat tire. For example, it is placed between the carcass ply layer and the inner liner rubber, and is made of rubber that has the same hardness or higher hardness than the side rubber. be.

The tire 10 further includes a power receiving unit 30 and an electronic device 24.
The power receiving unit 30 receives power from outside the tire through wireless power transmission. Power receiving unit 30 includes power receiving coil 18 .
The power receiving coil 18 is provided on the side inner surface S1 facing the cavity region C of the tire 10, and receives an AC magnetic field transmitted through the side rubber 42 of the side portion S, the carcass ply layer 14, and the inner liner rubber 48, thereby receiving an AC magnetic field. This is the part that generates AC power according to the Depending on the position of the power receiving coil 18, the alternating current magnetic field that the power receiving coil 18 receives may also pass through the rim cushion rubber 46. Further, depending on the configuration of the rubber of the side portion S, the alternating current magnetic field received by the power receiving coil 18 may also pass through other rubber such as an auxiliary filler, a run flat liner, a bead filler, etc. The tire cavity region C is a region surrounded by the inner circumferential surface of the tire and the bottom surface of the rim of the wheel 11 assembled with the rim (a portion of the wheel is shown in FIGS. 3 and subsequent figures), and is filled with air to a predetermined internal pressure. The power receiving coil 18 is a circular coil that extends around the tire circumferential direction along the side inner surface S1. The power receiving coil 18 in the example shown in FIG. 2 is a one-turn circular coil. FIG. 2 is a plan view of the power receiving coil 18. The power receiving coil 18 is provided at the side S of the pair of side parts S that is arranged so as to face the side of the vehicle (inside the vehicle) on which the tire 10 is mounted via the wheel 11 .
The power receiving unit 30 further includes a rectifier circuit and a stabilizing circuit (not shown), and the AC power generated by the power receiving coil 18 is converted into DC power and becomes power at a predetermined voltage.

The electronic device 24 includes a sensor section 20 and a communication device 22. The sensor unit 20 includes a sensor element (not shown) that is driven by receiving DC power converted from AC power generated by the power receiving coil 18 . The sensor element is, for example, an acceleration sensor that measures the deformation behavior of the tread portion T of the tire 10 during rolling, although it is not particularly limited. The sensor unit 20 may further include an arithmetic processing circuit (not shown) that processes data of measurement results measured by the sensor element through arithmetic processing.
The communication device 22 is a part that transmits all of the data measured by the sensor unit 20 or processed information to a communication device (not shown) outside the tire by wire or wirelessly, and transmits the DC power converted from the generated AC power. Receives supply and drives.
A power line (not shown) extending from the power receiving unit 30 is connected to the sensor section 20 and the communication device 22. The DC power from the power receiving unit 30 is used for driving power for the sensor unit 20 and driving power for the communication device 22 (power for signal processing, transmission, etc.).

The alternating current magnetic field received by the power receiving coil 18 is generated, for example, by a power transmitting unit 104 including an alternating current power supply device 102 and a power transmitting coil 100 shown in FIG. The AC power supply device 102 may be supplied with power from a battery mounted on the vehicle body, or it may be supplied with power directly or via a rectifier/regulator from regenerative power generated by an alternator or drive motor without going through a battery. may be supplied. The power transmission coil 100 is provided at a base that does not rotate relative to the rotation of the tire 10, for example, at a non-rotating portion of a suspension (eg, a knuckle). A capacitor that forms a resonant circuit together with the power transmitting coil 100 is connected to the power transmitting coil 100, and is arranged within a rectangular area indicated by the reference numeral 100c in FIG. The power transmission unit 104 generates AC power using an inverter provided in the AC power supply device 102, and generates an AC magnetic field M using the power transmission coil 100.
According to one embodiment, power is transmitted from the power transmission unit 104 to the power reception unit 30 using a magnetic resonance method. In the magnetic resonance method, by matching the resonant frequency in the circuit of the power transmitting unit 104 with the resonant frequency in the circuit of the power receiving unit 30, the AC magnetic field generated by the power transmitting coil 100 causes the power receiving coil 18 to resonate. That is, an alternating current flows through the power receiving coil 18 due to resonance, and by rectifying this alternating current, direct current power can be obtained.
The magnetic resonance method has higher power transmission efficiency and longer transmission distance than the conventional electromagnetic induction method. From this point of view, it is preferable to match the resonance frequencies of the power transmission unit 104 and the power reception unit 30. The resonance frequency is adjusted, for example, by adjusting the inductance of the coils of the power transmission unit 104 and the power reception unit 30, and the capacitance within the resonance circuit. On the other hand, since transmission efficiency increases by shortening the transmission distance as much as possible, the power receiving coil 18 is provided in the side portion S as described above. Thereby, the transmission distance with the power transmission coil 100 provided in the non-rotating portion of the suspension is shortened, and high transmission efficiency can be obtained.
In addition, when using the magnetic resonance method, if there is a conductive material such as a metal near the receiving coil 18, loss due to eddy current will occur and the transmission efficiency will decrease. , the bead wire of the bead core 12).

As described above, the power receiving coil 18 is a circular coil that extends around the tire circumferential direction along the side inner surface S1. Therefore, the position and length of the circumferential portion of the power receiving coil 18 facing the power transmitting coil 100 do not substantially change due to rotation of the tire 10, and fluctuations in transmitted power are suppressed. Therefore, even when the vehicle is stopped or running at low speed, the amount of power supplied to the electronic device remains constant. In this way, according to the power receiving coil 18, power can be supplied at any time regardless of whether the vehicle is running or stopped or the vehicle speed. It is preferable that the receiving coil 18 has a circular shape with a constant curvature. Moreover, it is preferable that the power receiving coil 18 is arranged so as to go around a concentric circle of the side portion S centered on the rotation center axis of the tire 10. Note that the tire circumferential direction refers to a direction around the tire rotation center axis. The concentric positions of the side portions S are determined with the tire 10 not in contact with the ground. In this way, the power receiving coil 18 is a loop-shaped coil that forms a closed area that includes the tire rotation center axis on the inner circumferential side, so the area of the side inner surface S1 that the power receiving coil 18 occupies in the tire radial direction is small. be. Therefore, even if the receiving coil 18 is provided in a thin portion of the side portion S where the amount of vertical deflection due to the rolling of the tire 10 is large, it is unlikely to peel off or fall off from the side inner surface S1. On the other hand, when multiple coils are provided adjacent to each other in the tire circumferential direction on the side inner surface, the coils occupy a large area of the side inner surface in the tire radial direction, and deform to follow the vertical deflection of the side part. Since the amount of deformation of the coil is large, the coil is likely to peel off or fall off from the inner surface of the side.

In the tire 10 of this embodiment, the tire axial thickness of the side portion S at the position of the side inner surface S1 where the power receiving coil 18 is provided is Ts [mm] (see FIG. 3), and the tire axial thickness of the side portion S is Ts [mm] (see FIG. 3). When the minimum thickness in the axial direction of the tire over the radial direction is Tmin [mm], the ratio Ts/Tmin is 1.0 to 5.5. The tire axial direction refers to a direction parallel to the tire rotation center axis. The tire axial direction is parallel to the tire width direction. FIG. 3 is a cross-sectional view illustrating the arrangement of the power receiving coil 18. By providing the receiving coil 18 in the thin portion of the side portion S in this manner, attenuation of the alternating current magnetic field passing through the side portion S can be minimized, and transmission efficiency can be increased. As described above, according to the present embodiment, it is possible to improve transmission efficiency while suppressing fluctuations in transmitted power when power is supplied to an electronic device. The ratio Ts/Tmin is more preferably 4.0 or less. The tire axial thickness Ts of the side portion S is the total thickness of the side rubber 42, carcass ply layer 14, and inner liner rubber 48 when the power receiving coil 18 is provided at the position shown in FIG.
In addition, the rubber of tires generates heat when the vehicle is driven. In addition, the power receiving coil may also generate heat due to wireless power transfer, so if the power receiving coil is placed on the side of the rubber where a large amount of heat is generated, the heat generated by the rubber will not be dissipated, which may cause tire failure. There are cases. In the tire 10 of this embodiment, since the power receiving coil 18 is provided in the thinner side portion S as described above, the generated heat is more easily released than in the thicker side portion S. .
Furthermore, as described above, the thin portion of the side portion S is subject to a large amount of vertical deflection due to the rolling of the tire 10, and depending on the form of the receiving coil, it may cause peeling or falling off from the side inner surface S1. However, since the power receiving coil 18 is a circular coil, the amount of deformation that follows the deflection of the side portion is small compared to a conventional power receiving coil that has a power receiving area extending in the tire radial direction, and the power receiving coil 18 is Durability is improved.
The side portion S is a portion of the rim that protrudes outward in the tire width direction from the outer position of the tire radial direction, and is 1.5 times or more, preferably twice or more, the minimum thickness Tmin of the side portion S of the tire shaft. The range of the ratio Ts/Tmin is preferably 1.0 to 5.5, and preferably 1.0 to 4.2 when it has a portion having the maximum thickness in the direction (rim protection portion). It is more preferable. The side portion S shown in FIG. 1 has a rim protection portion. When the side portion S does not have a rim protection portion, the ratio Ts/Tmin preferably ranges from 1.0 to 3.3, more preferably from 1.0 to 3.0. When the side part S has a run flat liner, the range of the ratio Ts/Tmin is preferably 1.0 to 1.8, and 1.0 to 1, regardless of the presence or absence of the rim protect part. More preferably, it is .5. Note that both ends of the side portion in the tire radial direction are, for example, both ends of the side rubber region exposed on the tire outer surface on the opposite side to the tire inner surface of the side portion in the tire radial direction.

In addition, since the power receiving coil 18 is provided on the side inner surface S1 of the side portion S, heat generated during generation of AC power is easily released compared to a case where at least a portion of the power receiving coil 18 is embedded within the side portion S. ,preferable.
Note that the power receiving coil 18 can be fixed to the inner side surface S1 by, for example, bonding the coil to the inner peripheral surface of the tire with an adhesive or the like, or by a known fixing method.

In the power supply system of one embodiment, power is wirelessly transmitted from the power transmission unit 104 to the power reception unit 30 provided on the tire 10 assembled to the wheel 11, and power is supplied to the electronic device 24. The power supply system includes a power transmission unit 104 and a power reception unit 30.
The power transmission unit 104 includes a power transmission coil 100 that is provided at a non-rotating portion of the tire 10 and generates an alternating current magnetic field. The power transmitting coil 100 is disposed on the side opposite to the power receiving coil 18 with respect to the side portion S, specifically, on the outer side of the side portion S in the tire width direction.
Power receiving unit 30 is provided in tire 10 .
Specifically, as described above, the power receiving unit 30 includes the power receiving coil 18, and the electronic device 24 includes the sensor section 20 and the communication device 22. As described above, the power receiving coil 18 is provided on the side inner surface S1 of the side portion S facing the tire cavity region C of the tire 10, receives the alternating current magnetic field generated from the power transmitting coil 100 and transmitted through the side portion S, and receives power. Coil 18 generates alternating current power.
In this power feeding system, the power receiving coil 18 is a circular coil that extends in the tire circumferential direction along the side inner surface S1, and the position in the tire radial direction on the side inner surface S1 where the power receiving coil 18 is provided. When the thickness of the side portion S is Ts [mm] and the minimum thickness of the side portion S in the tire radial direction is Tmin [mm], the ratio Ts/Tmin is 1.0 to 5.5. Therefore, it is possible to increase transmission efficiency while suppressing fluctuations in transmission power when power is supplied to an electronic device.

The power transmission coil 100 is preferably provided at a position facing the side portion S of the tire 10 in an unsprung region of a suspension of a vehicle on which the tire 10 is mounted. By arranging the power transmitting coil 100 in this manner, the power receiving coil 18 and the power transmitting coil 100 can be provided so as to substantially face each other, so that the power receiving coil 18 can efficiently receive the alternating current magnetic field.
The power transmission coil 100 is preferably provided, for example, in a damper case in the case of a strut suspension, or in a knuckle in the case of a multi-link suspension, with these as the base.
Moreover, according to one embodiment, it is preferable that one power transmission coil 100 is provided for one tire 10. When a plurality of power transmission coils 100 are provided adjacently, cross-coupling between adjacent power transmission coils 100 occurs, which tends to reduce power feeding efficiency.

It is preferable that the power transmission coil 100 has a planar power transmission region arranged to face the side portion S, as shown in FIG. The power transmission region is a part that generates an alternating magnetic field. FIG. 4 is a plan view of the power transmission coil 100. The power transmission coil 100 has an electric wire 100b wired in a spiral shape (spiral shape) on a non-magnetic substrate 100a. The electric wire 100b may be made of a conductive material printed on the non-magnetic substrate 100a, or a wire-like conductor may be arranged in a coil shape. The electric wires 100b wired in this manner form a power transmission area of the power transmission coil 100. By providing the non-magnetic substrate 100a at the base, the power transmission coil 100 can move together with the tire 10 during steering.

As shown in FIG. 4, the power transmission coil 100 preferably has an arc-shaped curvature portion 101a that extends according to a predetermined curvature within the plane of the power transmission region. In this case, as shown in FIG. 4 when viewed in the tire width direction, it is preferable that the curvature portion 101a forms a part of a section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil 18. FIG. 5(a) is a diagram showing the overlapping of the power transmitting coil 100 and the power receiving coil 18 when viewed in the tire width direction, and FIG. 5(b) is a partially enlarged view of FIG. 5(a). The power transmitting coil 100 shown in FIG. 5(b) and FIG. 6(b) to be referred to later is shown as a closed coil with one turn along the outline of the power transmitting coil 100 for easy explanation. By providing the power transmitting coil 100 with respect to the power receiving coil 18 in this way, the alternating current magnetic field from the power transmitting coil 100 can be received by a longer circumferential portion of the power receiving coil 18, and the transmission Increased efficiency. The curvature portion 101a in the example shown in FIG. 4 is a portion having an arc shape in the outermost portion along the tire radial direction in the power transmission region. By making such a part the curvature part 101a, it is easy to ensure a long arc length of the curvature part 101a, and it is easy to ensure a long part on the circumference of the power receiving coil 18 that receives the alternating magnetic field from the power transmitting coil 100. .

As shown in FIGS. 2, 5, and 6, the power receiving coil 18 extends so that both circumferential ends of the power receiving coil 18 deviate from the tire circumferential direction, so that the power receiving coil 18 is interrupted in the tire circumferential direction. It has a discontinuous portion 18a formed therein. FIG. 6(a) is a diagram showing the overlap between the power transmitting coil 100 and the discontinuous portion 18a of the power receiving coil 18 when viewed in the tire width direction, and FIG. 6(b) is a partially enlarged view of FIG. 6(a). It is a diagram. A capacitor that forms a resonant circuit together with the power receiving coil 18 is connected to the power lines at both ends of the power receiving coil 18 forming the interrupted portion 18a. In the example shown in FIGS. 5 and 6, the capacitor is arranged within a rectangular area indicated by reference numeral 18b. The distance L [mm] along the tire circumferential direction of the curved portion 101a of the power transmitting coil 100 is the distance d [mm] in the tire circumferential direction between both ends of the power receiving coil 18 at the discontinuous portion 18a (FIGS. 4, 6(b) ) is preferably 1/3 or less. Since the ratio d/L is 1/3 or less, when viewed in the tire width direction, the discontinuous portion 18a is a region of the side inner surface S1 that overlaps with the power transmission region of the power transmission coil 100 as the tire 10 rotates. Stable power transmission can be achieved even when passing through. Further, when the tire 10 stops rolling, the area through which the alternating current magnetic field generated by the power transmission coil 100 passes through the discontinuous portion 18a becomes smaller, and the power supply can be maintained. The ratio d/L is preferably 1/4 or less. On the other hand, it is preferable that the two power lines forming the interrupted portion 18a do not contact each other in order to prevent a decrease in transmission efficiency due to the proximity effect, and the ratio d/L is preferably 1/20 or more. Note that the length L of the curved portion 101a is preferably 50 to 180 mm in view of the balance between the magnitude of transmitted power and the installation space constraints of the base to which the power transmission coil 100 is attached.

It is preferable that the power receiving unit 30 further includes a second power receiving coil 28 when the power receiving coil 18 is referred to as the first power receiving coil 18 . The second power receiving coil 28 is provided on the side inner surface S1, and generates an alternating current magnetic field by receiving an alternating magnetic field transmitted through the side portion S. The second power receiving coil 28 is a circular coil that extends along the side inner surface S1 and concentrically with the first power receiving coil 18 in a circumferential direction of the tire. The resonant frequency in the circuit of the second power receiving coil 28 matches the resonant frequency in the circuit of the power transmitting unit 104, and the alternating current magnetic field generated by the power transmitting coil 100 causes the second power receiving coil 28 to resonate. As mentioned above, the resonant frequency in the circuit of the first power receiving coil 18 matches the resonant frequency in the circuit of the power transmitting coil 100, and as a result, it also matches the resonant frequency in the circuit of the second power receiving coil 28. Not only the AC magnetic field generated by the power transmitting coil 100 but also the AC magnetic field generated by the second power receiving coil 28 causes the first power receiving coil 18 to resonate. According to the inventor's study, it has been confirmed that by making the second power receiving coil 28 function as a relay coil in this way, larger AC power is generated in the first power receiving coil 18, and power feeding efficiency is greatly improved. Ta. Note that, unlike the first power receiving coil 18, the second power receiving coil 28 does not have a power line connected from the second power receiving coil 28 to the communication device 22, and is independent from the communication device 22.
When the thickness of the side portion S at the position of the side inner surface S1 where the second power receiving coil 28 is provided is Ts2 [mm], the ratio Ts2/Tmin is preferably 1.0 to 5.5. Thereby, the attenuation of the alternating current magnetic field that passes through the side portion S, which is received by the second power receiving coil 28, can be minimized, and the first power receiving coil 18 can be made to resonate strongly. The preferred range of Ts2/Tmin for each rubber configuration of the side portion S is the same as the above-described preferred range of the ratio Ts/Tmin for each rubber configuration of the side portion S.

If the first power receiving coil 18 is placed near the belt layer 16 and the steel cord of the bead core 12, a conductive material is placed near the transmission path of the alternating current magnetic field, causing loss due to eddy current, resulting in transmission efficiency. This is not preferable because it reduces the In particular, in low-profile tires, the distance between the belt layer 16 and the bead core 12 is narrow, and the distance between the alternating current magnetic field and the conductive material becomes short, so the alternating magnetic field may not reach the first power receiving coil 18 with sufficient strength. There is. In such a tire, the second power receiving coil 28 is used together with the first power receiving coil 18 to relay or amplify the alternating current magnetic field in the second power receiving coil 28, thereby supplementing the alternating current magnetic field that makes the first power receiving coil 18 resonate. This makes it possible to suppress a decrease in transmission efficiency. Therefore, among the first power receiving coil 18 and the second power receiving coil 28, the power receiving coil that is closer to the belt layer 16 and the steel cord of the bead core 12 is the first power receiving coil 18, and the power receiving coil that is farther away is the second power receiving coil. It is preferable to set it as 28.

The first power receiving coil 18 with respect to the average value (average distance) G [mm] of the distance (shortest distance) between the power transmission area of the power transmitting coil 100 and each of the first power receiving coil 18 and the second power receiving coil 28 (see FIG. 7) The ratio R/G of the interval R [mm] (see FIG. 7) in the tire radial direction between the second power receiving coil 28 and the second power receiving coil 28 is preferably 0.1 to 1.2, and preferably 0.2 to 1.0. It is preferable. FIG. 7 is a diagram illustrating the arrangement of the power transmitting coil 100 and the power receiving coils 18 and 28. In order to efficiently transmit power, it is preferable that the distance between power transmitting coil 100 and power receiving coils 18 and 28 be short. However, if the distance between the power transmitting coil 100 and the power receiving coils 18 and 28 is short, the possibility that the side part S will come into contact with the power transmitting coil 100 increases due to lateral deformation of the side part S during tire cornering. On the other hand, in a low-profile tire, the degree of lateral deformation of the side part S during tire cornering is small, and the possibility of the side part S coming into contact with the power transmission coil 100 is low, but as described above, the transmission efficiency is reduced. Cheap. Therefore, in a low-profile tire, the radial distance R between the first power receiving coil 18 and the second power receiving coil 28 is preferably narrow from the viewpoint of suppressing a decrease in transmission efficiency. When the ratio R/G is within the above range, it is possible to suppress a decrease in transmission efficiency while avoiding contact between the side portion S and the power transmission coil 100 in tires having various aspect ratios. The average distance G is preferably 10 to 50 mm. If the average distance G is short, there is a high possibility that the side part S will come into contact with the power transmission coil 100, while if the average distance G is long, the transmission distance will be too long and the transmission efficiency will tend to decrease.

The second power receiving coil 28 has a discontinuous portion 28a formed such that the second power receiving coil 28 is interrupted in the tire circumferential direction by extending both ends of the second power receiving coil 28 in the circumferential direction so as to deviate from the tire circumferential direction. are doing. A capacitor that forms a resonant circuit together with the second power receiving coil 28 is connected to the power lines at both ends of the second power receiving coil 28 forming the interrupted portion 28a. As shown in FIG. 8, the angle between the discontinuous portion 18a of the first power receiving coil 18 and the discontinuous portion 28a of the second power receiving coil 28 in the tire circumferential direction (around the tire rotation center axis Ax) is 4 degrees or more. It is preferable that FIG. 8 is a cross-sectional view illustrating the arrangement of the two power receiving coils 18 and 28. The angle formed is an angle formed between the center positions of the discontinuous portions 18a and 28a in the tire circumferential direction. If the angle formed by the discontinuous parts 18a, 28a is less than 4 degrees, the power lines forming the discontinuous parts 18a, 28a will be too close together, and the resonance circuit of one power receiving coil will be influenced by the power line of the other power receiving coil. Losses may occur. The angle formed above is preferably 5 degrees or more.

In a cross section passing through the curvature part 101a of the power transmission coil 100 and the tire 10 along the tire radial direction, a first radial region R1 where the curvature part 101a is located and a position opposite to the curvature part 101a with respect to the side part S. The second radial region R2 whose ends are the positions of the first power receiving coil 18 and the second power receiving coil 28 in the tire radial direction (facing the curved portion 101a with the side portion S sandwiched in between) is defined as As shown in 9, it is preferable that they are not separated in the tire radial direction. FIGS. 9A to 9D are cross-sectional views illustrating the positional relationship between the power transmitting coil 100 and the power receiving coils 18 and 28 along the tire radial direction. The first radial region R1 is a region in the tire radial direction whose ends are the outermost circumferential portion and the innermost circumferential portion in the tire radial direction of the electric wire 101b forming the curved portion 101a. When the power transmitting coil 100 and the power receiving coils 18 and 28 are arranged so that the two radial regions R1 and R2 are not separated from each other in the tire radial direction, the alternating current magnetic field generated by the power transmitting coil 100 is transferred to the first power receiving coil 18 and The second receiving coil 28 can receive the power with sufficient strength, which increases the effect of improving transmission efficiency. The two radial regions R1 and R2 are specified when the tire 10 is mounted on the vehicle and filled with air to a predetermined internal pressure (the air pressure of the relevant tire size specified by the vehicle; if not specified, 230 kPa). Ru. In the example shown in FIGS. 9(a) and 9(b), the first radial region R1 and the second radial region R2 are in contact with each other in the tire radial direction, and FIGS. 9(c) and 9(d) ), the first radial region R1 and the second radial region R2 overlap in the tire circumferential direction. In order to receive the alternating current magnetic field generated by the power transmitting coil 100 with sufficient strength in the power receiving coils 18 and 28 and to increase the effect of increasing transmission efficiency, as in the examples shown in FIGS. 9(b) and 9(c). It is preferable that the first radial region R1 and the second radial region R2 overlap in the tire circumferential direction.

As shown in FIG. 10, the power transmission unit 104 preferably further includes a magnetic body 110 disposed on the side opposite to the side portion S with respect to the power transmission coil 100. FIG. 10 is a diagram illustrating the magnetic body 110. The relative magnetic permeability of the magnetic body 110 at the frequency of the alternating magnetic field generated by the power transmission coil 100 is 30 to 300. The magnetic body 110 in the example shown in FIG. 10 is a magnetic sheet having a surface parallel to the plane of the power transmission region of the power transmission coil 100. The magnetic body 110 in the example shown in FIG. 10 is in contact with the power transmission coil 100 and is laminated on the surface of the nonmagnetic substrate 100a on the side portion S side. The thickness of the magnetic sheet is preferably 0.01 to 0.5 mm. The power transmission coil 100 is disposed, for example, in a wheel house of a vehicle that accommodates a suspension, and on the side opposite to the side where the power reception coils 18 and 28 are provided with respect to the power transmission coil 100 (the back side of the power transmission coil 100), an aluminum , structural materials and parts containing metals (conductors) such as iron are arranged. Therefore, an eddy current is generated on the surface of the conductor due to the alternating magnetic field generated by the power transmission coil 100, and the resulting loss may reduce transmission efficiency or cause the metal member to generate heat. Therefore, it is preferable to arrange a magnetic sheet to absorb or block the magnetic flux generated by the power transmission coil 100. More preferably, as shown in FIG. 11, the magnetic body 110 is preferably arranged at a distance h [mm] from the power transmission coil 100. By leaving the interval h, it is possible to prevent the magnetic sheet from becoming magnetically saturated and reducing its effectiveness. FIG. 11 is a diagram illustrating the arrangement of the magnetic body 110, the power transmitting coil 100, and the power receiving coils 18 and 28. A non-magnetic substrate 100a in contact with the power transmission coil 100 is laminated on the surface of the side portion S of the magnetic body 110 in the example shown in FIG. It is preferable that the distance between the power transmitting coil 100 and the power receiving coils 18, 28 is short. Therefore, the ratio h/G of the interval h to the average value (average distance) G [mm] of the distance (shortest distance) between the power transmission area of the power transmission coil 100 and each of the power reception coils 18 and 28 is 0.01 to 0.5. It is preferable that

It is preferable that the power receiving coils 18, 28 and the power transmitting coil 100 are each formed of a single conductive wire made of a single wire. Such a coil is suitable for feeding power using a magnetic resonance method using electromagnetic waves having a frequency in the MHz band. The frequency range when power is supplied using the magnetic resonance method is preferably in the range of 1 MHz to 1 GHz, more preferably in the range of 2 to 20 MHz. In addition, the power receiving coils 18 and 28 that are made up of a single conductive wire made of a single wire can prevent an increase in AC resistance due to the proximity effect compared to a given power receiving coil that has the same cross-sectional area and is made up of a power line made of stranded wires. can.

The diameter of the conducting wire (single wire) in the power transmitting coil 100 is preferably larger than the diameter of the conducting wire (single wire) in the power receiving coils 18 and 28. As shown in FIG. 12, the diameter D1 of the single wire conductor is the length obtained by excluding the thickness D2 of the coating layer covering the conductor from the diameter of the single wire. The conductor is made of copper, for example, and the coating layer is made of resin, for example. The larger the diameter of the power transmitting coil 100 and the power receiving coils 18 and 28 is, the more advantageous it is from the viewpoint of increasing transmission efficiency by generating a strong alternating current magnetic field and generating large alternating current power. However, if the diameter of the power receiving coils 18, 28 is excessively large, the distortion when deformed following the deformation of the side portion S is large, and durability may deteriorate. Furthermore, if the diameter of the power receiving coils 18, 28 is too large, there is a risk that they may peel off or fall off from the side inner surface S1 due to centrifugal force during rolling. Therefore, by making the diameter of the conducting wire (single wire) in the power transmitting coil 100 thicker than the diameter of the conducting wire (single wire) in the power receiving coils 18, 28, the thickness of the power receiving coils 18, 28 is limited. This can complement the effect of improving transmission efficiency that is suppressed by this, and further ensure the durability of the power receiving coils 18 and 28. The diameter of the conducting wire (single wire) in the receiving coils 18, 28 is preferably 0.5 to 1.0 mm. The diameter of the conductor (single wire) in the power transmission coil 100 is preferably 0.8 to 1.5 mm. Further, the number of turns of the power transmission coil 100 is preferably 3 to 12 turns.

The side portion S at the position of the side inner surface S1 where the first power receiving coil 18 is provided with respect to the distance in the tire width direction (shortest distance) G1 [mm] (see FIG. 13) between the power transmitting coil 100 and the first power receiving coil 18. The ratio Ts1/G1 of the thickness Ts1 [mm] (see FIG. 13) and the distance (shortest distance) in the tire width direction between the power transmitting coil 100 and the second power receiving coil 28 G2 [mm] (see FIG. 13), At least one of the ratio Ts2/G2 of the thickness Ts2 [mm] (see FIG. 13) of the side portion S at the position of the side inner surface S1 where the second power receiving coil 28 is provided is 0.1 to 0.7. is preferred, and both are more preferably from 0.1 to 0.7. FIG. 13 is a cross-sectional view illustrating the relationship between the distances G1, G2 between the power transmitting coil 100 and the power receiving coils 18, 28, and the thicknesses Ts1, Ts2 of the side portions S. As described above, in order to efficiently transmit power, it is preferable that the distance between power transmitting coil 100 and power receiving coils 18 and 28 be short. However, if the distance between the power transmitting coil 100 and the power receiving coils 18, 28 is too short, the degree of lateral deformation of the side portion S becomes too large relative to the distances G1, G2, and the fluctuation range of the transmitted power becomes large. I end up. Furthermore, if the distance between the power transmitting coil 100 and the power receiving coils 18 and 28 is too short, there is a high possibility that the side part S will come into contact with the power transmitting coil 100 due to lateral deformation of the side part S during tire cornering. By limiting at least one of the ratio Ts1/G1 and the ratio Ts2/G2 within the above range, it is possible to suppress fluctuations in transmission efficiency, avoid contact between the side portion S and the power transmission coil 100, and efficiently operate the transmission coil 100. Power can be transmitted. The ratio Ts1/G1 and the ratio Ts2/G2 are each more preferably from 0.2 to 0.6, and even more preferably from 0.15 to 0.55. The distance between the power transmitting coil 100 and the power receiving coils 18, 28 is adjusted, for example, by adjusting the thickness along the tire width direction of a pedestal for attaching the nonmagnetic substrate 100a or the magnetic body 110 to the base.

As shown in FIG. 14, the cross-section of the tire 10 with respect to the height along the tire radial direction based on the inner end of the bead portion B in the tire radial direction (the direction toward or away from the rotation center axis Ax of the tire 10). The height is Sh [mm], the height of the position of the side inner surface S1 where the thickness of the side portion S is Tmin is Ht [mm], and the position of the side inner surface S1 where the first power receiving coil 18 is provided. When the height of is H1 [mm], the height of the position of the side inner surface S1 where the second power receiving coil 28 is provided is H2 [mm], and the oblateness of the tire 10 is P x 100 [%]. ,
Ht-Sh×P/4≦H1≦Ht+Sh×P/4, and Ht-Sh×P/4≦H2≦Ht+Sh×P/4,
It is preferable to satisfy at least one of the following, and it is more preferable to satisfy both. FIG. 14 is a diagram illustrating the relationship between the height positions of the power receiving coils 18 and 28 and the aspect ratio P. The low-profile tire 10 has a small amount of vertical deflection of the side portion S, suppresses deformation of the power receiving coils 18, 28 due to rolling of the tire 10, and easily ensures durability of the power receiving coils 18, 28. On the other hand, in a low-profile tire 10, the transmission efficiency is likely to decrease due to the belt layer 16 and the steel cord of the bead core 12, and the ratio Ts1/Tmin or the ratio Ts2/Tmin at the position where the power receiving coils 18, 28 are provided is outside the above range. Even if the conditions are satisfied, it may be difficult to suppress a decrease in transmission efficiency. Therefore, it is preferable that the lower the tire is, the closer the height position of the power receiving coils 18, 28 is to the height position of the side portion S having the thickness Tmin. If the height positions of the power receiving coils 18 and 28 are set so as to satisfy at least one of the above two relationships, the durability of the power receiving coils 18 and 28 and the suppression of reduction in transmission efficiency are particularly well balanced. The aspect ratio P is preferably 0.30 to 0.65.

The various dimensions such as R, R2, Sh, Ht, H1, H2, etc. mentioned above in this specification are measured in an unloaded state in which the tire 10 is mounted on a regular rim and filled with a regular internal pressure. "Regular rims" are rims that are specified for each tire by the standard system that includes the standard on which the tire is based, such as standard rims specified by JATMA, "Design Rim" specified by TRA, etc. ” or “Measuring Rim” as defined in ETRTO. However, if the tire 10 is a tire installed on a new vehicle, a genuine wheel to which the tire 10 is assembled is used. "Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standard on which the tire is based. The maximum value stated in "LIMITS AT VARIOUS COLD INFLATION PRESSURES" refers to "INFLATION PRESSURES" specified in ETRTO, and if the tire 10 is for a passenger car, it is 230 kPa. However, if the tire 10 is a tire installed on a new vehicle, the air pressure is set to the value specified by the vehicle.

When viewed in the tire width direction (direction parallel to the rotation center axis Ax of the tire 10), the power transmission coil 100 is aligned in the tire circumferential direction of an imaginary line extending vertically upward from the rotation center axis Ax of the tire 10, as shown in FIG. is preferably located within an angular range of 45 degrees (total of 90 degrees) on each side of the. FIG. 15 is a diagram illustrating an angular range in the tire circumferential direction (around the rotation center axis Ax of the tire 10) in which the power transmission coil 100 is arranged. When the power transmitting coil 100 is located near the ground contact surface of the tire 10, the height positions of the power receiving coils 18 and 28 change with the vertical deflection deformation of the tire 10, so that the height position of the power transmitting coil 100 changes. Misalignment is likely to occur. Therefore, the power receiving coils 18 and 28 may not be able to sufficiently receive the alternating current magnetic field generated by the power transmitting coil 100, and there is a possibility that the transmission efficiency may be reduced. When the power transmitting coil 100 is arranged within the above-mentioned angle range, the influence on the transmitted power due to the change in the height position of the power receiving coils 18, 28 due to the vertical bending deformation of the tire 10 can be reduced, and a decrease in transmission efficiency can be suppressed. be able to.

Although the tire and power supply system of the present invention have been described in detail above, the tire and power supply system of the present invention are not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention. Of course it's good too.

10 Tire 11 Wheel 12 Bead core 12a Bead bottom surface 14 Carcass ply layer 16 Belt layer 18 Power receiving coil (first power receiving coil)
18a Interruption section 20 Sensor section 22 Communication device 24 Electronic device 28 Power receiving coil (second power receiving coil)
28a Interrupted portion 30 Power receiving unit 40 Tread rubber 42 Side rubber 44 Bead filler rubber 46 Rim cushion rubber 48 Inner liner rubber 100 Power transmission coil 100a Non-magnetic substrate 100b Electric wire 101a Curved portion 102 AC power supply device 104 Power transmission unit 110 Magnetic body

Claims (15)

1. A tire equipped with a power receiving coil that generates electric power by receiving an alternating magnetic field from outside the tire,
   A power receiving coil is provided on the inner surface of the side of the side portion between the tread portion and the bead portion facing the tire cavity region of the tire, and generates AC power by receiving an alternating current magnetic field transmitted through the side portion. Prepare,
   The power receiving coil is a circular coil that extends around the inner surface of the side in a circumferential direction of the tire,
   When the thickness of the side portion at the position of the inner surface of the side where the power receiving coil is provided is Ts, and the minimum thickness of the side portion over the tire radial direction is Tmin, the ratio Ts/Tmin is 1.0 to 5.5.
2. When the power receiving coil is referred to as a first power receiving coil, the power receiving coil further includes a second power receiving coil that is provided on the inner surface of the side and generates an alternating current magnetic field by receiving an alternating magnetic field transmitted through the side part,
   The tire according to claim 1, wherein the second power receiving coil is a circular coil that extends along the inner surface of the side and concentrically with the first power receiving coil in a circumferential direction of the tire.
3. The first power receiving coil and the second power receiving coil extend so that both ends of the first power receiving coil and the second power receiving coil deviate from the tire circumferential direction so that the power receiving coil is interrupted in the tire circumferential direction. having a discontinuity formed;
   The tire according to claim 2, wherein an angle formed by the discontinuous portion of the first power receiving coil and the discontinuous portion of the second power receiving coil in the tire circumferential direction is 4 degrees or more.
4. Regarding the height along the tire radial direction based on the inner end of the tire radial direction of the bead portion, the cross-sectional height of the tire is Sh, and the thickness of the side portion is Tmin on the side inner surface. The height of the position on the side inner surface where the first power receiving coil is provided is H1, and the height of the position on the side inner surface where the second power receiving coil is provided. When is H2 and the aspect ratio of the tire is P x 100 [%],
   Ht-Sh×P/4≦H1≦Ht+Sh×P/4, and Ht-Sh×P/4≦H2≦Ht+Sh×P/4,
   The tire according to claim 2 or 3, which satisfies at least one of the following.
5. A power supply system that wirelessly transmits power from a power transmission unit to a power reception unit provided on a tire to supply power to an electronic device connected to the power reception unit,
   The power transmission unit includes a power transmission coil that is provided at a base that does not rotate with respect to the tire and generates an alternating current magnetic field,
   The power receiving unit is provided on the inner surface of the side of the tire between the tread and the bead of the tire, facing the tire cavity area, and the power receiving unit is configured to receive power generated from the power transmission coil and transmitted through the side. comprising a power receiving coil that generates AC power by receiving the AC magnetic field,
   The electronic device is driven by being supplied with electric power converted from the AC power to DC power in the power receiving unit,
   The power transmitting coil is provided at the base and is disposed on a side opposite to the power receiving coil with respect to the side part,
   The power receiving coil is a circular coil that extends around the inner surface of the side in a circumferential direction of the tire,
   When the thickness of the side portion at a position in the tire radial direction of the side inner surface where the power receiving coil is provided is Ts, and the minimum thickness of the side portion across the tire radial direction is Tmin, A power supply system characterized in that the ratio Ts/Tmin is 1.0 to 5.5.
6. The power transmission coil has a planar power transmission area arranged to face the side part,
   The power transmission coil has an arc-shaped curvature portion that extends according to a predetermined curvature in the plane of the power transmission region,
   The power feeding system according to claim 5, wherein the curvature portion forms a part of a section in the circumferential direction of a circle that is concentric with the circular shape of the power receiving coil when viewed in the tire width direction.
7. The power receiving coil has a discontinuous portion formed such that the power receiving coil is interrupted in the tire circumferential direction by extending both ends of the power receiving coil deviating from the tire circumferential direction,
   The power supply system according to claim 6, wherein a ratio d/L of a distance d in the tire circumferential direction between the both ends of the discontinuous portion to a length L of the curvature portion in the tire circumferential direction is 1/3 or less. .
8. When the power receiving coil is referred to as a first power receiving coil, the power receiving unit further includes a second power receiving coil that is provided on the inner surface of the side and generates an alternating current magnetic field by receiving an alternating magnetic field transmitted through the side part,
   The power feeding system according to claim 6 or 7, wherein the second power receiving coil is a circular coil that extends along the inner surface of the side and concentrically with the first power receiving coil in a circumferential direction of the tire. .
9. The ratio R/G of the distance R in the tire radial direction between the first power receiving coil and the second power receiving coil to the average value G of the distance between the power transmission region and each of the first power receiving coil and the second power receiving coil is The power supply system according to claim 8, which is 0.1 to 1.2.
10. In a cross section passing through the curvature part along the tire radial direction, a first radial region where the curvature part is located, the first power receiving coil located on the side opposite to the curvature part with respect to the side part, and The power supply system according to claim 8, wherein the second power receiving coil is not separated in the tire radial direction from a second radial region having both ends at positions of the second power receiving coils in the tire radial direction.
11. The power transmission unit is a magnetic body disposed on a side opposite to the side portion with respect to the power transmission coil, and has a relative magnetic permeability of 30 to 300 at a frequency of an alternating current magnetic field generated by the power transmission coil. The power feeding system according to claim 8, further comprising:
12. The magnetic body is arranged on a side opposite to the side part with respect to the power transmission coil, with a distance h from the power transmission coil,
    According to claim 11, a ratio h/G of the interval h to an average value G of the distance between the power transmission region and each of the first power receiving coil and the second power receiving coil is 0.01 to 0.5. power supply system.
13. a ratio Ts1/G1 of the thickness Ts1 of the side portion at the position of the inner surface of the side where the first power receiving coil is provided to the distance G1 in the tire width direction between the power transmitting coil and the first power receiving coil; At least one of the ratio Ts2/G2 of the thickness Ts2 of the side portion at the position of the inner surface of the side where the second power receiving coil is provided to the distance G2 in the tire width direction between the power transmission region and the second power receiving coil is The power supply system according to claim 8, which is 0.1 to 0.7.
14. The power transmitting coil and the power receiving coil each include a single conductive wire made of a single wire,
    The power supply system according to any one of claims 5 to 7, wherein the diameter of the conductor of the conductor in the power transmission coil is larger than the diameter of the conductor of the conductor in the power reception coil.
15. 8. The power transmission coil according to claim 5, wherein the power transmission coil is located within an angular range of 45 degrees on each side of a line extending vertically upward from the central axis of rotation of the tire in the tire circumferential direction. The power supply system according to any one of the items above.

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