Tire assembly

Abstract

This tire assembly comprises: a tire that is to be mounted on a vehicle; a first power generator unit; and a second power generator unit different from the first power generator unit. The first power generator unit has a power generator disposed on the inner surface of the tire, and a pressing member that is fixed on the inner surface of the tire at both sides of the power generator so as to stride over the power generator in the circumferential direction of the tire and that is deformable in response to deformation of the tire. The second power generator unit has a power generator fixed on the inner surface of the tire, and a weight member that overlaps the power generator from a side opposite to the inner surface across the power generator.

Description

tire assembly

[0001] The present invention relates to a tire assembly in which a power generator is incorporated within a tire.

[0002] International Publication No. WO 2022 / 180916 (Patent Document 1) discloses a tire assembly incorporating a contact-charging type power generator. This power generator includes a positively charged insulating film and a negatively charged insulating film, and generates an electromotive force by changing the true contact area of ​​the contact surfaces between the insulating films. In the tire assembly disclosed in Patent Document 1, the power generator is disposed between the inner surface of the tire and an elastic body disposed inside the tire. The elastic body biases the power generator toward the inner surface of the tire. This makes it possible to efficiently utilize the impact that the tire receives from the road surface to promote charging of the insulating film.

[0003] International Publication No. 2022 / 180916

[0004] The tire assembly described in Patent Document 1 primarily utilizes changes in strain in the tire to promote charging of the insulating film. However, with this configuration, depending on the tire rotation speed, the effect of promoting charging may be weakened, and sufficient power may not be obtained. For this reason, a tire assembly that can obtain sufficient power regardless of the tire rotation speed has been desired.

[0005] An object of the present invention is to provide a tire assembly that can obtain sufficient power over a wider range of rotational speeds.

[0006] A tire assembly according to a first aspect of the present invention includes a tire to be mounted on a vehicle, one or more first power generation units, and one or more second power generation units different from the first power generation units. The first power generation unit has a power generation body arranged on the inner surface of the tire, and presser members fixed to the inner surface of the tire on both sides of the power generation body so as to straddle the power generation body along the circumferential direction of the tire, the presser members being deformable in response to tire deformation. The second power generation unit has a power generation body fixed to the inner surface of the tire, and a weight member overlapping the power generation body from the side opposite the inner surface, with the power generation body sandwiched therebetween. The power generating body has a first member having a first insulating film that forms a first surface, and a second member having a second insulating film that faces the first surface and forms a second surface that is in contact with the first surface, the first member and the second member being configured so that the real contact area between the first surface and the second surface changes depending on the force applied to the first member and the second member, and the first insulating film and the second insulating film are configured so that one becomes positively charged and the other becomes negatively charged as the real contact area changes.

[0007] A tire assembly according to a second aspect of the present invention is the tire assembly according to the first aspect, comprising a plurality of the first power generation units, the plurality of first power generation units including at least one first power generation unit having a weight member of mass M1 arranged between the power generation body and the pressing member, and at least one first power generation unit having a weight member of mass M2 arranged between the power generation body and the pressing member, where M1 > M2.

[0008] A tire assembly according to a third aspect of the present invention is the tire assembly according to the first or second aspect, comprising a plurality of the second power generation units, the plurality of second power generation units including at least one second power generation unit having a weight member with a mass M3 and at least one second power generation unit having a weight member with a mass M4, where M3<M4.

[0009] A tire assembly according to a fourth aspect of the present invention is a tire assembly according to any one of the first aspect to the third aspect, comprising a plurality of the second power generation units, the plurality of second power generation units including at least one second power generation unit having an area of ​​the first surface and the second surface S1 and at least one second power generation unit having an area of ​​the first surface and the second surface S2, wherein S1 < S2.

[0010] A tire assembly according to a fifth aspect of the present invention is the tire assembly according to any one of the first to fourth aspects, further comprising one or more circuits that receive power from each of the first power generation unit and the second power generation unit and are connected to an external computer so as to be able to communicate data with the external computer.

[0011] A tire assembly according to a sixth aspect of the present invention is the tire assembly according to any one of the first to fifth aspects, wherein the first power generation unit, the second power generation unit, and the circuit are distributed and arranged at four or more locations along the circumferential direction of the tire.

[0012] A tire assembly according to a seventh aspect of the present invention is the tire assembly according to any one of the first to sixth aspects, wherein the first power generation unit, the second power generation unit, and the circuit are dispersedly arranged at six or less locations along the circumferential direction of the tire.

[0013] A tire assembly according to an eighth aspect of the present invention is the tire assembly according to any one of the first to seventh aspects, further comprising a weight that reduces the mass difference between the dispersedly arranged first power generation unit, the second power generation unit, and the circuit.

[0014] A tire assembly according to a ninth aspect of the present invention is a tire assembly according to any one of the first to eighth aspects, wherein at least one of the first power generation unit, the second power generation unit, and the circuit is positioned at a position shifted from a point at which the tire is divided into N equal intervals along the circumferential direction.

[0015] A tire assembly according to a tenth aspect of the present invention is the tire assembly according to any one of the first aspect to the ninth aspect, wherein the pressing member includes at least one of rubber, a thermoplastic elastomer, a thermoplastic resin, and a thermosetting resin.

[0016] A tire assembly according to an eleventh aspect of the present invention is the tire assembly according to any one of the first to tenth aspects, wherein the presser member includes a composite material of rubber and carbon fiber.

[0017] A tire assembly according to a twelfth aspect of the present invention is the tire assembly according to any one of the first to eleventh aspects, wherein the computer is configured to monitor at least one of the air pressure of the tire, the internal temperature of the tire, and the rotational speed of the tire.

[0018] A thirteenth aspect of the present invention is a method for manufacturing a tire assembly including: a tire to be fitted to a vehicle; and a power generating body having a first member having a first insulating film forming a first surface, and a second member having a second insulating film forming a second surface facing the first surface and in contact with the first surface, the first member and the second member being configured so that a real contact area between the first surface and the second surface changes in response to a force applied to the first member and the second member, and the first insulating film and the second insulating film are configured so that one becomes positively charged and the other becomes negatively charged as the real contact area changes, the method comprising the following steps: preparing the tire; preparing at least three power generating bodies including a first power generating body, a second power generating body, and a third power generating body; and arranging each of the at least three power generating bodies on an inner surface of the tire. The arrangement of the at least three power generators on the inner surface of the tire includes fixing pressure members, which are deformable in response to deformation of the tire, on the inner surface of the tire on both sides of the first power generator so as to straddle the first power generator along the circumferential direction of the tire, so that the amount of power generated by the first power generator peaks in a first speed range of the tire rotational speed, and arranging a first weight member having a first mass between the first power generator and the pressure member; and placing a second weight member having a second mass between the power generator and the pressure member from the opposite side of the inner surface to the power generator so that the amount of power generated by the second power generator peaks in a second speed range of the tire rotational speed. and fixing another pressure member to the inner surface of the tire on both sides of the third power generator so as to straddle the third power generator along the circumferential direction of the tire so that the amount of power generated by the third power generator peaks in a third speed region of the tire rotational speed, and disposing a third weight member having a third mass smaller than the first mass between the third power generator and the another pressure member, or placing a fourth weight member having a fourth mass larger than the second mass on the third power generator from the side opposite the inner surface, sandwiching the third power generator therebetween, so that the amount of power generated by the third power generator peaks in a third speed region of the tire rotational speed.The first speed region is a region slower than the third speed region, and the third speed region is a region slower than the second speed region.

[0019] The present invention provides a tire assembly that can obtain sufficient power over a wider range of rotational speeds.

[0020] 1 is a diagram showing a state in which a tire assembly according to the first embodiment is mounted on a vehicle. A developed view of a tire assembly according to the first embodiment. A longitudinal cross-sectional view of a tire assembly according to the first embodiment. A cross-sectional view of a power generator according to the first embodiment. A diagram explaining the charging principle of a power generator. A graph showing findings based on the results of experiments conducted by the inventors. A diagram explaining the behavior of a first unit. A diagram explaining the behavior of a second unit. A longitudinal cross-sectional view of a tire assembly according to the second embodiment. A graph showing findings based on the results of experiments conducted by the inventors. A longitudinal cross-sectional view of a tire assembly according to the third embodiment. A graph showing findings based on the results of experiments conducted by the inventors. A longitudinal cross-sectional view of a tire assembly according to the fourth embodiment. A developed view of a tire assembly according to a modified example. A diagram showing the configuration of an experimental apparatus. A graph showing the results of experiment 2. A graph showing the results of experiment 3.

[0021] Hereinafter, tire assemblies according to some embodiments of the present invention will be described with reference to the drawings. Note that the dimensions of each element in the drawings may be exaggerated for the sake of convenience.

[0022] A. First Embodiment <1. ​​Overall Configuration> Fig. 1 is a diagram showing a tire assembly 1 according to a first embodiment of the present invention mounted on each hub (hereinafter also referred to as "wheel") of a vehicle 8. The type of vehicle 8 is not particularly limited, but in this embodiment it is a four-wheel vehicle and includes a left front wheel FL, a right front wheel FR, a left rear wheel RL, and a right rear wheel RR. The tire assembly 1 of this embodiment is mounted on each wheel and mounted on the wheels FL, FR, RL, and RR of the vehicle 8.

[0023] The vehicle 8 is equipped with an on-board system 9 (hereinafter, sometimes simply referred to as "system 9"). The system 9 is configured to monitor the condition of the tire assembly 1 (or the tire 2 included in the tire assembly 1), for example, at least one of the air pressure, internal temperature, and rotational speed of the tire assembly 1. In other words, the system 9 may be a known tire pressure monitoring system (TPMS) or tire monitoring system (TMS). The system 9 is configured to include at least one of an air pressure sensor, a temperature sensor, and a rotational speed sensor attached to the wheel or the tire assembly 1. The tire assembly 1 is configured to generate power while the vehicle 8 is traveling and supply power to devices such as sensors included in the system 9.

[0024] The system 9 may further include a control device 80 mounted on the vehicle 8 and capable of wired or wireless data communication with the above sensors. The control device 80 is a microcomputer or the like in terms of hardware, and may be pre-installed in the vehicle 8 or may be installed in the vehicle 8 later. The control device 80 is configured to acquire data on at least one of the air pressure, internal temperature, and rotation speed detected by the above sensors, and monitor at least one of the air pressure, internal temperature, and rotation speed. Furthermore, the control device 80 may be connected to a display, and may display on the display the ON / OFF status of the above sensors and data output by the above sensors, such as the air pressure, internal temperature, and rotation speed.

[0025] 2. Configuration of Tire Assembly The configuration of a tire assembly 1 according to this embodiment will now be described with reference to the drawings. FIG. 2 is a schematic diagram of the tire assembly 1 when unfolded, and FIG. 3 is a longitudinal cross-sectional view of the tire assembly 1 (a cross-sectional view obtained by cutting the tread portion 20 in half along the circumferential direction). The tire assembly 1 of this embodiment includes a tire 2, two first power generation units 3 (hereinafter also referred to as "first units 3"), one second power generation unit 4 (hereinafter also referred to as "second unit 4"), rectifier circuits 5A and 5B, a power supply control circuit 6, and two weights 7A and 7B. These are distributed and arranged at four locations along the circumferential direction of the tire 2. Each component will now be described.

[0026] [Tire] The tire 2 is made of vulcanized rubber or the like and has elasticity. As shown in Figures 2 and 3, the tire 2 has a tread portion 20, a shoulder portion 21, a sidewall portion 22, and a bead portion 23. The tread portion 20 defines the circumferential side surface of the tire assembly 1 and moves the vehicle 8 forward by contacting the road surface and generating friction. The shoulder portion 21 is adjacent to the tread portion 20 and the sidewall portion 22. The sidewall portion 22 forms the surfaces on both sides of the sidewall portion 22 and flexes to absorb impact from the road surface. The bead portion 23 incorporates a bead wire (not shown) therein and is fixed to a rim formed on the periphery of a wheel (not shown).

[0027] [First Unit] The first unit 3 includes a power generator 10A, a presser member 30, a weight member 31, and a tape 32. The power generator 10A is a device that utilizes contact charging and includes a first member 11 and a second member 12 that are stacked and rectangular in plan view (see FIG. 4 ). The detailed configuration of the power generator 10A will be described later. The first member 11 and the second member 12 are stacked on top of each other and secured by wrapping tape 32 around their peripheries. The tape 32 has an adhesive surface with an adhesive on one side of the base material, and is wrapped around the power generator 10A so that this adhesive surface adheres to the first base material 113 of the first member 11 and the second base material 123 of the second member 12, which will be described later. The tape 32 is not particularly limited as long as it has sufficient strength and adhesiveness. However, from the viewpoint of ensuring heat resistance, a glass cloth tape using a glass cloth as a base material is preferred.

[0028] The tape 32 wrapped around the power generator 10A is fixed to the inner surface 200 of the tread 20 on the substrate surface opposite the adhesive surface. As a result, the power generator 10A is placed on the inner surface 200 of the tread 20 via the tape 32. Here, the power generator 10A may be placed so that either the first member 11 or the second member 12 is located on the inner surface 200 side. Furthermore, there are no particular limitations on the method for fixing the tape 32 to the inner surface 200, and it may be, for example, adhesion with an adhesive.

[0029] The weight member 31 is a plate-shaped member having a rectangular appearance generally similar to that of the power generator 10A in a plan view. The weight member 31 is layered on the power generator 10A so as to be located radially inward of the power generator 10A relative to the central axis A1 of the tire assembly 1. In this embodiment, the weight member 31 is fixed to the base surface of the tape 32 facing radially inward. That is, the weight member 31 may be layered on either the first member 11 or the second member 12. The method for fixing the weight member 31 to the tape 32 is not particularly limited, and may be, for example, bonding with an adhesive. The weight member 31 applies a force to the power generator 10A that brings the first member 11 and the second member 12 closer to each other, thereby promoting power generation by the power generator 10A during rotation of the tire assembly 1. The weight member 31 is preferably arranged so as to overlap the entire first member 11 and the second member 12 so as to apply a force uniformly in the planar direction of the power generator 10A. The material constituting the weight member 31 is not particularly limited, and may be, for example, metal, resin, rubber, or a composite material thereof.

[0030] The presser member 30 is a member that is fixed to the inner surface 200 along the circumferential direction of the tire 2 so as to straddle the power generator 10A and the tape 32. In other words, both ends of the presser member 30 along the circumferential direction of the tire 2 are fixed to the inner surface 200 on both sides of the power generator 10A and the tape 32. As a result, the presser member 30 sandwiches the power generator 10A and the weight member 31 between itself and the inner surface 200. The presser member 30 is made of a material that is deformable in response to deformation of the tire 2. As a result, the shape of the space surrounded by the presser member 30 and the inner surface 200 changes during rotation of the tire 2. Note that both ends of the presser member 30 in the width direction (direction along the central axis A1) may not be fixed to the inner surface 200, and the space may be open in the width direction. Furthermore, the presser member 30 of this embodiment is configured to entirely cover the power generator 10A and the weight member 31 from the radially inner side of the tire assembly 1.

[0031] The pressing member 30 is preferably fixed to the inner surface 200 with a tension that ensures sufficient room for the power generator 10A to deform while appropriately suppressing the separation between the first member 11 and the second member 12 of the power generator 10A. For example, the pressing member 30 can be fixed so that when the portion of the tire assembly 1 to which the power generator 10A is fixed is placed on a flat surface, the lower surface of the pressing member 30 is spaced a predetermined distance from the upper surface of the weight member 31. The predetermined distance is preferably 0.05 mm or more and 5 mm or less. The method for fixing the pressing member 30 to the inner surface 200 is not particularly limited, and may be, for example, adhesion with an adhesive.

[0032] The material constituting the pressing member 30 is preferably a material that has flexibility while also having high tensile strength, and preferably includes at least one of rubber, thermoplastic elastomer, thermoplastic resin, and thermosetting resin, for example. Furthermore, from the viewpoint of maintaining the mass balance of the tire assembly 1, the material constituting the pressing member 30 is preferably low-density. An example of such a material is a composite material of rubber and carbon fiber (Carbon Fiber Rubber (CFR)). The pressing member 30 according to this embodiment is a sheet made of CFR. The specific gravity of a 1.0 mm-thick CFR sheet is approximately 1.12 to 1.16, and the tensile strength is approximately 71.4 MPa to 121.3 MPa.

[0033] [Second Unit] The second unit 4 includes a power generation body 10B, a weight member 41, and a tape 42. The power generation body 10B has a similar configuration to the power generation body 10A, and therefore the detailed configuration will be described below. Like the power generation body 10A, the power generation body 10B has a first member 11 and a second member 12 that are stacked on top of each other and secured by wrapping tape 42 around their peripheries. Like the weight member 31, the weight member 41 is a plate-shaped member that has roughly the same rectangular appearance as the power generation body 10B in a plan view. The same explanations as for the tape 32 and the weight member 31 apply to the tape 42 and the weight member 41, respectively, and therefore will not be repeated.

[0034] Unlike the first unit 3, the second unit 4 does not have the pressing member 30. Therefore, if the dimensions and density of the power generator 10B and the weight member 41 are the same as those of the power generator 10A and the weight member 31, the second unit 4 will be lighter than the first unit 3.

[0035] [Rectifier Circuit] The rectifier circuits 5A and 5B are connected to the power generating elements 10A and 10B, respectively, via conductors and rectify the currents output from the power generating elements 10A and 10B into direct current. Each rectifier circuit 5A is connected to the power generating element 10A, and the rectifier circuit 5B is connected to the power generating element 10B. In this manner, one rectifier circuit is generally connected to one power generating element. The rectifier circuits 5A and 5B are not particularly limited and may be, for example, circuits using known diodes. In this embodiment, two rectifier circuits 5A and one rectifier circuit 5B are mounted together on a single substrate 5 and fixedly positioned on the inner surface 200 adjacent to the second unit 4. The reason why the rectifier circuits 5A and 5B are positioned adjacent to the second unit 4 will be described later. The current rectified by the rectifier circuits 5A and 5B is sent to the power supply control circuit 6 via conductors.

[0036] [Power Supply Control Circuit] The power supply control circuit 6 is connected to the rectifier circuits 5A and 5B and the system 9. The power supply control circuit 6 is configured to supply the current rectified by the rectifier circuits 5A and 5B to the system 9 and to control the operation of the system 9. More specifically, the power supply control circuit 6 has a function of controlling the ON / OFF of at least one device included in the system 9 and a function of controlling the current supply so that the device operates stably. The power supply control circuit 6 of this embodiment is configured to temporarily store the current rectified by the rectifier circuits 5A and 5B in a capacitor, turn on at least one device when the capacitor voltage exceeds a predetermined upper limit, and turn off the device when the capacitor voltage falls below a predetermined lower limit. The device may be a sensor, a microcomputer, a wireless communication device, or the like. Note that the board on which the power supply control circuit 6 is mounted may also be equipped with at least one of the above devices and a storage battery other than the capacitor.

[0037] [Weights] The weights 7A and 7B are arranged not for the purpose of pressurizing the power generation bodies 10A and 10B, but for the purpose of suppressing radial force variations (RFV) resulting from mass imbalance in the tire assembly 1 and suppressing vibration and noise of the tire assembly 1. In this embodiment, of the first unit 3, the second unit 4, and the power supply control circuit 6, the second unit 4 has the smallest mass, and the power supply control circuit 6 has the largest mass. Therefore, in this embodiment, the weights and the substrate 5 are arranged so that the masses of the first unit 3 and the second unit 4 are close to the mass of the power supply control circuit 6, thereby reducing the mass difference between the first unit 3, the second unit 4, and the power supply control circuit 6. Specifically, the weights 7A are arranged adjacent to each of the first units 3, and the weights 7B and the substrate 5 are arranged adjacent to the second unit 4. Note that the weights 7A, 7B, and the substrate 5 may be arranged near the respective power generation body units within a range where a "mass" (described later) can be regarded as a mass point, or may be arranged at a distance from the respective power generation body units. The masses of weights 7A and 7B can be determined appropriately depending on the masses of first unit 3, second unit 4, substrate 5 (including rectifier circuits 5A and 5B), and power supply control circuit 6.

[0038] The material constituting the weights 7A and 7B is not particularly limited and can be selected as appropriate. Furthermore, the method for fixing the weights 7A and 7B to the inner surface 200 is not particularly limited and may be, for example, adhesion with an adhesive. The weight 7A may be fixed to the surface of the pressing member 30 on the central axis A1 side rather than being fixed directly to the inner surface 200. In this case, the weight 7A is preferably fixed to a portion of the pressing member 30 that is fixed to the inner surface 200 so as not to inhibit the deformation of the pressing member 30.

[0039] [Arrangement] The group of first unit 3 and weight 7A, the group of second unit 4, weight 7B, and substrate 5, and the power supply control circuit 6 can be considered to be pseudo mass points that are respectively distributed and arranged in the circumferential direction of tire 2. From the viewpoint of suppressing vibration of tire assembly 1 caused by higher-order components of RFV, the mass of each pseudo mass point (total mass of members constituting the group) is preferably 30 g or less if tire 2 is for a passenger car, and is preferably 40 g or less if tire 2 is for a large vehicle such as a truck or bus. Note that in order to consider the groups as mass points, the length of each group along the circumferential direction of tire 2 is preferably 15% or less of the total circumferential length of the inner surface 200.

[0040] The pseudo mass points are preferably distributed at four or more locations along the circumferential direction of the tire 2, and more preferably at four to six locations. This distributes the first-order component of RFV, which affects vibration, to the vicinity of fourth- to sixth-order components, which are less likely to affect both vibration and noise, thereby suppressing undesirable effects of RFV. Furthermore, when the pseudo mass points are distributed at N locations along the circumferential direction of the tire 2, it is preferable that at least one of these pseudo mass points is located at a position offset from N equally spaced locations along the circumferential direction of the tire 2. For example, in FIGS. 2 and 3 , if the position where one first unit 3 and weight 7A are located is taken as the reference (0°), the second unit 4, substrate 5, and weight 7B are located at 100°, not 90°. Furthermore, the power supply control circuit 6 is located at 275°, not 270°. In this way, it is possible to mitigate the peak of the Nth-order component of vibration and noise by disposing at least one of the pseudo mass points so as to be shifted from the 360° / N rotational position on the inner surface 200. Note that the angle of shift from the 360° / N rotational position is preferably equal to or greater than (0.05×360° / N) and equal to or less than (0.26×360° / N).

[0041] The reference point in the circumferential direction of the tire 2 can be, for example, the lightest position in terms of the mass balance of the entire tire 2. Then, the tire 2 is placed on a horizontal table with the outside side facing up, and the position at which the pseudo mass point is to be placed can be determined based on the angle from the reference point measured with the center of the tire 2 aligned with a predetermined position on the table.

[0042] <3. Power Generator> All elements of the power generators 10A and 10B may be configured with the same dimensions and materials, or may differ from each other in at least some dimensions and materials. The following describes the configuration common to the power generators 10A and 10B. Below, when there is no particular distinction between the power generators 10A and 10B, they will be collectively referred to as the "power generator 10."

[0043] Fig. 4 is a cross-sectional view showing the configuration of the power generating unit 10 according to this embodiment. As shown in Fig. 4, the power generating unit 10 includes a first member 11 and a second member 12, with the members stacked in this order. The power generating unit 10 according to this embodiment has a square shape of the same size in a plan view, but the shape of the power generating unit 10 is not limited to this. The orientation of the power generating unit 10 during use is not limited to the orientation shown in Fig. 4.

[0044] [First Member] The first member 11 includes a first base material 113, a first electrode 112, and a first insulating film 111, which are layered in this order. Each of the elements 111 to 113 of the first member 11 has a square shape of the same size in a plan view. The first base material 113 is made of a flexible material or a viscoelastic material, such as a resin or an elastomer, so that it can deform when subjected to an external force. In this embodiment, the first base material 113 is made of silicone rubber. A large number of projections and recesses are formed on the surface of the first base material 113 that contacts the first electrode 112. As a result, projections and recesses corresponding to the projections and recesses of the first base material 113 are reproduced on the first surface 110 formed by the first insulating film 111 via the first electrode 112.

[0045] There are no particular limitations on the configuration of the unevenness of the first base material 113. For example, the unevenness may be formed regularly across the surface direction of the first base material 113, or may be formed somewhat randomly. In addition, there are no particular limitations on the cross-sectional shape of the unevenness.

[0046] The first electrode 112 is a part for extracting the electric charge generated in the first insulating film 111 to the outside of the power generator 10 and is arranged on the back surface of the first surface 110 so as to contact the first insulating film 111. The first electrode 112 can be made of a conductive material, examples of which include a conductive film of Ag, Cu, etc., and conductive cloth. The composition of the conductive cloth is not particularly limited, but may be a nonwoven fabric made of a polymer material plated with a metal, or a fabric made of a polymer material mixed with metal fibers, etc. The first electrode 112 is flexible and can deform in response to deformation of the first substrate 113. Furthermore, the surface of the first electrode 112 in contact with the first insulating film 111 reproduces the unevenness corresponding to the unevenness of the first substrate 113.

[0047] The first insulating film 111 is a flexible film made of an insulator. In this embodiment, the surface of the first insulating film 111 opposite the first electrode 112 corresponds to the first surface 110. The first substrate 113 forms irregularities on the first surface 110 that correspond to the irregularities of the first substrate 113. The first surface 110 faces and contacts a second surface 120 formed by a second insulating film 121 (described later). When the actual contact area between the first surface 110 and the second surface 120 changes due to pressure applied to the power generation body 10, the first insulating film 111 is charged with a polarity opposite to that of the second insulating film 121. In other words, when the second insulating film 121 is positively charged, the first insulating film 111 is negatively charged. Conversely, when the second insulating film 121 is negatively charged, the first insulating film 111 is positively charged.

[0048] The ten-point mean roughness of the first surface 110 is preferably 100 μm or more and 2 mm or less. The ten-point mean roughness is measured according to JIS B 0601:2001.

[0049] Note that when the first surface 110 and the second surface 120 are said to be "in contact," it is sufficient that the first surface 110 and the second surface 120 are in partial contact, and it is also acceptable for there to be portions where the first surface 110 and the second surface 120 are not in contact. In the power generating body 10 of this embodiment, the first surface 110 and the second surface 120 both have square shapes of the same size and are configured to overlap entirely. In other words, in the power generating body 10 of this embodiment, the first surface 110 and the second surface 120 are in contact entirely.

[0050] [Second Member] The second member 12 includes a second substrate 123, a second electrode 122, and a second insulating film 121, which are layered in this order. Each of the elements 121 to 123 of the second member 12 has a square shape of the same size in a plan view. Like the first substrate 113, the second substrate 123 is made of a flexible or viscoelastic material, such as a resin or elastomer, so that it can deform when subjected to an external force. In this embodiment, the second substrate 123 is made of silicone rubber. A large number of irregularities are formed on the surface of the second substrate 123 that contacts the second electrode 122. As a result, irregularities corresponding to the irregularities of the second substrate 123 are reproduced on the second surface 120 formed by the second insulating film 121 via the second electrode 122.

[0051] There are no particular limitations on the configuration of the projections and recesses on the second base material 123. For example, the projections and recesses may be formed regularly across the surface of the second base material 123, or may be formed somewhat randomly. In addition, there are no particular limitations on the cross-sectional shape of the projections and recesses.

[0052] The second electrode 122 is a part for extracting the charge generated in the second insulating film 121 to the outside of the power generator 10 and is arranged on the back surface of the second surface 120 so as to contact the second insulating film 121. The second electrode 122 can be made of a conductive material, examples of which include a conductive film of Ag, Cu, etc., and conductive cloth. The composition of the conductive cloth is not particularly limited, but may be a nonwoven fabric made of a polymer material plated with a metal, or a fabric made of a polymer material mixed with metal fibers, etc. The second electrode 122 is flexible and can deform in response to deformation of the second substrate 123. Furthermore, the second electrode 122 reproduces the unevenness corresponding to the unevenness of the second substrate 123 on the surface in contact with the second insulating film 121.

[0053] The second insulating film 121 is a flexible film made of an insulator different from that of the first insulating film 111. In this embodiment, the surface of the second insulating film 121 opposite the second electrode 122 corresponds to the second surface 120. The second substrate 123 forms irregularities on the second surface 120 that correspond to the irregularities of the second substrate 123. The second surface 120 faces the first surface 110 formed by the first insulating film 111 and is in contact with the first surface 110. When the actual contact area between the first surface 110 and the second surface 120 changes due to pressure applied to the power generation body 10, the second insulating film 121 is charged with a polarity opposite to that of the first insulating film 111. In other words, when the first insulating film 111 is positively charged, the second insulating film 121 is negatively charged. Conversely, when the first insulating film 111 is negatively charged, the second insulating film 121 is positively charged.

[0054] The ten-point mean roughness of the second surface 120 is preferably 100 μm or more and 2 mm or less. The ten-point mean roughness is measured according to JIS B 0601:2001.

[0055] [Materials, etc.] The material constituting the first insulating film 111 and the second insulating film 121 can be selected from the group consisting of, for example, diamond-like carbon (DLC), perfluoropolyether, polymethyl methacrylate, nylon, polyvinyl alcohol, polyester, polyisobutylene, polyurethane (PU), polyethylene terephthalate, polyvinyl butyral, polychloroprene, natural rubber, polyacrylonitrile, polydiphenol carbonate, chlorinated polyether, polyvinylidene chloride, polystyrene, polyethylene, polypropylene, polyimide, polyvinyl chloride, polydimethylsiloxane, polytetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and other materials whose main component is an organic fluorocarbon.

[0056] From the viewpoint of increasing the electromotive force of the power generator 10, it is preferable to select a pair of materials from the above group that are farther apart in the triboelectric series. Note that either the first insulating film 111 or the second insulating film 121 may be positively charged and either may be negatively charged. In this embodiment, one of the first insulating film 111 and the second insulating film 121 is made of polyimide, and the other of the first insulating film 111 and the second insulating film 121 is made of nylon. The polyimide is negatively charged, and the nylon is positively charged.

[0057] At least one of the thickness W1 of the first insulating film 111 and the thickness W2 of the second insulating film 121 is preferably 20 μm or less. Furthermore, it is more preferable that both the thickness W1 and the thickness W2 are 20 μm or less. Note that the drawing does not necessarily reflect the dimensions of each element of the actual power generating body 10.

[0058] [Charging Principle of the Power Generator 10] The first insulating film 111 and the second insulating film 121 become charged by the following operation. As shown in Fig. 4, the first surface 110 and the second surface 120 of this embodiment both have unevenness, and even when no external pressure is applied to the power generator 10, they do not completely separate, leaving some areas in contact with each other. In this state, the distance (average surface spacing) between the average surface of the first surface 110 and the average surface of the second surface 120 is relatively large, which is equivalent to a state in which the actual contact area between the first surface 110 and the second surface 120 is relatively small.

[0059] Next, when pressure is applied to the power generator 10 so that the first insulating film 111 and the second insulating film 121 are brought closer together, the shapes of the first surface 110 and the second surface 120 change, the irregularities become slightly flatter, and the average inter-surface spacing decreases, as shown in FIG. 5 . In other words, the real contact area increases. Furthermore, when the pressure applied to the power generator 10 is removed, the first insulating film 111 and the second insulating film 121 move away from each other again, and the average inter-surface spacing increases. In other words, the real contact area between the first surface 110 and the second surface 120 decreases. When the real contact area changes in this way, the amount of charge on the first insulating film 111 and the second insulating film 121 increases compared to the initial state, and more charge is induced in the first electrode 112 and the second electrode 122.

[0060] In a configuration in which unevenness is formed on at least one of the first surface 110 and the second surface 120, the true contact area also changes to some extent due to the relative movement in the planar direction between the first insulating film 111 and the second insulating film 121. Therefore, among the forces applied to the power generator 10, not only forces that increase or decrease the average inter-plane spacing but also forces that cause the first insulating film 111 and the second insulating film 121 to slide relatively in the planar direction also contribute to the power generation of the power generator 10.

[0061] 4. Operating Principle of Tire Assembly The first unit 3 and second unit 4 of the tire assembly 1 behave differently depending on the rotational speed of the tire assembly 1. This makes it possible to stabilize the amount of power generation of the tire assembly 1 over a wider range of rotational speeds. The reason for this will be explained below.

[0062] The inventors prepared a tire assembly including only the first unit 3 and a tire assembly including only the second unit 4, and measured the power generation amount P [μW] of these tire assemblies at rotational speeds V equivalent to 20 km / h to 120 km / h. As a result, the inventors found that there is a significant difference in the speed range of the tire assemblies where the peak of the power generation amount P appears between the first unit 3 and the second unit 4. FIG. 6 is a V-P graph that schematically expresses this. As can be seen from FIG. 6, in the speed range of 20 km / h to 60 km / h, the power generation amount P of the first unit 3 is larger, and a peak of the power generation amount P of the first unit 3 appears. However, in the speed range of 60 km / h or higher, the power generation amount P of the second unit 4 exceeds the power generation amount P of the first unit 3, and a peak of the power generation amount P of the second unit 4 appears.

[0063] This shows that in the low-speed region (60 km / h or less), the presence of the pressure member 30 contributes to an increase in the amount of change in the true contact area of ​​the generator 10, but in the high-speed region (60 km / h or more), the pressure member 30 restricts the deformation of the generator 10, and the amount of change in the true contact area actually decreases. In other words, the change in the true contact area of ​​the generator 10 incorporated in the tire 2 may be caused primarily by changes in the strain of the tire 2, or may be caused primarily by changes in the radial acceleration (or centrifugal force) acting on the tire 2. In the low-speed region where the change in radial acceleration is relatively small, it is preferable to induce the deformation of the generator 10 by the pressure member 30, and in the high-speed region where the change in radial acceleration is relatively large, it is preferable not to restrict the deformation of the generator 10 by the pressure member 30.

[0064] In light of the above, the inventors decided to design the tire assembly 1 to include both a first unit 3 and a second unit 4. FIG. 7A is a diagram illustrating the behavior of the first unit 3 as it moves through positions A to E in the figure when the tire assembly 1 rotates on the road surface in the direction of arrow A2. FIG. 7B is a diagram illustrating the behavior of the second unit 4 as it moves through positions A to E in the figure when the tire assembly 1 rotates on the road surface in the direction of arrow A2. Position A is the position immediately before the tire 2 contacts the ground, and position B is the position immediately after the tire 2 contacts the ground. Position C corresponds to the circumferential center of the contact patch of the tire 2. Position D is the position immediately before the tire 2 leaves the road surface, and position E is the position immediately after the tire 2 leaves the road surface. In the graphs of FIGS. 7A and 7B, time t=0 is defined as the time when the first unit 3 or the second unit 4 is at position C. In these graphs, the rotational speed of the tire assembly 1 corresponds to 40 km / h to 50 km / h. In these graphs, the output voltage values ​​are normalized.

[0065] As shown in FIG. 7A , the output voltage of the first unit 3 reaches its maximum peak at position C. This is thought to be due to the following: First, from position A to position B, the pressing member 30 is compressed circumferentially in conjunction with the strain of the tire 2, causing the first surface 110 and the second surface 120 of the power generator 10A to move apart. Then, at position C, the tire 2 is stretched circumferentially, and in conjunction with this, the pressing member 30 is suddenly pulled to both sides, resulting in the first surface 110 and the second surface 120 moving closer together. Next, from position D to position E, the pressing member 30 is compressed circumferentially again in conjunction with the strain of the tire 2, causing the first surface 110 and the second surface 120 to move apart. In this way, it is thought that the output voltage of the first unit 3 reaches its maximum peak at position C because the direction of the force applied to the pressing member 30 is reversed at position C. That is, in the first unit 3, the change in the circumferential strain of the tire 2 is the dominant factor in the change in the true contact area of ​​the power generating body 10A.

[0066] On the other hand, as shown in FIG. 7B , the absolute value of the output voltage of the second unit 4 peaks in opposite directions at positions B and D, resulting in a phase shift with respect to the first unit 3. This is believed to be due to the following: From position A to position B, a radial acceleration α is applied to the weight member 41, causing the true contact area to change in a direction in which the first surface 110 and the second surface 120 approach each other. Next, from position B through position C to position D, the weight member 41 is mainly subjected to gravitational acceleration g, causing the first surface 110 and the second surface 120 to rapidly separate. This separation is greater in magnitude due to the absence of the pressing member 30. As a result, the change in the true contact area is greatest from position B to position D. Next, from position D to position E, the radial acceleration α begins to be applied to the weight member 41 again, causing a change in the true contact area. In other words, in the second unit 4, changes in the radial acceleration (or centrifugal force) of the tire 2 are the dominant factor in changing the true contact area of ​​the power generator 10B. Since the change in radial acceleration increases as the rotational speed of the tire assembly 1 increases, it can be said that the change in the true contact area of ​​the power generating body 10B increases at higher rotational speeds.

[0067] As described above, the tire assembly 1 includes the different first unit 3 and second unit 4, thereby realizing a sufficient amount of power generation over a wider speed range.

[0068] B. Second Embodiment Figure 8 is a longitudinal cross-sectional view of a tire assembly 1W according to a second embodiment. Tire assembly 1W of this embodiment differs from tire assembly 1 in that the two first units are first unit 3A and first unit 3B. Below, differences between tire assembly 1W and tire assembly 1 will be mainly described, and elements that share a configuration with tire assembly 1 will be assigned the same reference numerals and will not be described again.

[0069] The first unit 3A includes a power generator 10W, a presser member 30W, a weight member 31A, and a tape 32W. These have the same functions as the power generator 10A, the presser member 30, the weight member 31, and the tape 32 of the first unit 3, respectively, and are assembled in the same manner as the first unit 3. The first unit 3B includes a power generator 10W, a presser member 30W, a weight member 31B, and a tape 32W. These also have the same functions as the power generator 10A, the presser member 30, the weight member 31, and the tape 32 of the first unit 3, respectively, and are assembled in the same manner as the first unit 3. However, the mass M1 of the weight member 31A is greater than the mass M2 of the weight member 31B. That is, M1 > M2. Therefore, in the tire assembly 1W, to correct the mass imbalance of the tire assembly 1W, a weight 7C is disposed adjacent to the first unit 3A, and a weight 7D is disposed adjacent to the first unit 3B. The weight 7C is lighter than the weight 7D.

[0070] FIG. 9 is a V-P graph based on an experiment conducted by the inventors, which schematically shows the rotational speed V (equivalent to km / h) of the tire assembly 1W, the power generation amount P [μW] of each of the first unit 3A, first unit 3B, and second unit 4 in the tire assembly 1W, and the total power generation amount thereof. As shown in FIG. 9, the power generation amount P of the first unit 3A peaks around 30 to 40 km / h, the power generation amount P of the first unit 3B peaks around 60 km / h, and the power generation amount P of the second unit 4 peaks around 90 to 100 km / h. In this way, the first unit 3A, first unit 3B, and second unit 4 each exhibit a peak of the power generation amount P corresponding to a different rotational speed range. As a result, the tire assembly 1W as a whole can maintain a more stable power generation amount compared to the tire assembly 1, particularly in the speed range around 60 km / h. According to the inventors' investigations, when different power generation units are incorporated separately into a tire and the amount of power generation P relative to the rotational speed V of the tire assembly is measured, the V-P characteristics of the entire tire assembly can be estimated by superimposing the amounts of power generation P of each unit.

[0071] The behavior of the first unit 3A and the first unit 3B when the tire assembly 1W rotates is similar to the behavior of the first unit 3 shown in FIG. 7A . As described above, power generation by the first unit 3 is primarily due to circumferential strain of the tire 2, and the peak power generation occurs in the low-speed region of approximately 60 km / h or less. However, within the low-speed region, at relatively high speeds (e.g., 40 km / h to 60 km / h), the contribution of changes in the radial acceleration of the tire 2 to changes in the true contact area of ​​the power generator 10X gradually increases. Therefore, at relatively high speeds, a lighter weight member reduces the contribution of changes in radial acceleration to changes in the true contact area of ​​the power generator 10W, thereby maintaining a relatively large contribution of changes in strain of the tire 2. In addition, as the natural frequency of the first unit increases, changes in the true contact area become more active at relatively high speeds. As a result, even for first units having the same structure, if the mass of the weight member is made smaller, it is possible to adjust the speed range at which the amount of power generation peaks to a higher speed, whereas if the mass of the weight member is made larger, it is possible to adjust the speed range at which the amount of power generation peaks to a lower speed.

[0072] According to the inventors' investigations, in order to make the power generation amount of the first unit 3A peak in the speed range of 20 km / h to 40 km / h and the power generation amount of the first unit 3B peak in the speed range of 50 km / h to 60 km / h, it is preferable that 1 / 4≦(M2 / M1)≦1 / 3. The reason for this is due to the change in the natural frequency of the first unit. In the first unit 3A, the natural frequency f n is expressed by the following equation: where k is a constant. On the other hand, if M2 = n × M1, the natural frequency f bn is expressed by the following formula: From this, if the speed at which the power generation amount of the first unit 3A reaches its peak is V (equivalent to km / h), the speed Vb at which the power generation amount of the first unit 3B reaches its peak can be considered to be expressed by the following formula. Based on the above, for example, when V = 30, setting M2 to 1 / 3 to 1 / 5 times M1 theoretically allows Vb to be adjusted from 52 km / h to 67 km / h. However, if M2 is less than 1 / 3 of M1, the rigidity of the first unit 3B decreases, and the actual Vb tends to not exceed 60 km / h and to move lower than that. Furthermore, setting M2 = 0 results in an overall decrease in the amount of power generated, so making M2 too small is not desirable. Therefore, preferably, setting 1 / 4 ≦ (M2 / M1) ≦ 1 / 3 stabilizes the amount of power generated by the entire tire assembly 1W over a wider speed range and improves the V-P characteristics of the tire assembly 1W. Note that the dimensions of each component of the power generator 10W are the same for the first unit 3A and the first unit 3B.

[0073] C. Third Embodiment Figure 10 is a longitudinal cross-sectional view of a tire assembly 1X according to a third embodiment. The tire assembly 1X of this embodiment differs from the tire assembly 1 in that it includes one first unit 3, and two second units 4A and 4B. The following description of the tire assembly 1X will focus on the differences from the tire assembly 1, and elements that share the same configuration as the tire assembly 1 will be denoted by the same reference numerals and will not be described again.

[0074] The second unit 4A has a power generator 10X, a weight member 41A, and a tape 42X. These have the same functions as the power generator 10B, weight member 41, and tape 42 of the second unit 4, respectively, and are assembled in the same manner as the second unit 4. The second unit 4B has a power generator 10X, a weight member 41B, and a tape 42X. These also have the same functions as the power generator 10B, weight member 41, and tape 42 of the second unit 4, respectively, and are assembled in the same manner as the second unit 4. However, the mass M3 of the weight member 41A is smaller than the mass M4 of the weight member 41B. In other words, M3 < M4. The weights 7E and 7F are appropriately positioned near the second unit 4A and second unit 4B, respectively, to correct the mass imbalance of the tire assembly 1X. In the tire assembly 1X, the substrate 5 on which one rectifier circuit 5A and two rectifier circuits 5B are mounted is disposed adjacent to the second unit 4A, and therefore the masses of the weights 7E and 7F are set taking into consideration the masses of the substrate 5 and the rectifier circuits 5A and 5B. The rectifier circuit 5A is connected to the power generation body 10A, and the rectifier circuit 5B is connected to the power generation bodies 10X of the second unit 4A and second unit 4B, respectively.

[0075] FIG. 11 is a V-P graph based on an experiment conducted by the inventors, which schematically shows the rotational speed V (equivalent to km / h) of the tire assembly 1X, the power generation amount P [μW] of each of the first unit 3, the second unit 4A, and the second unit 4B in the tire assembly 1X, and the total power generation amount thereof. As shown in FIG. 11, the power generation amount P of the first unit 3 peaks around 30 to 40 km / h, the power generation amount P of the second unit 4B peaks around 60 to 80 km / h, and the power generation amount P of the second unit 4A peaks around 90 to 100 km / h. In this way, the first unit 3, the second unit 4A, and the second unit 4B each exhibit a peak power generation amount P corresponding to a different rotational speed range. As a result, the tire assembly 1X as a whole can maintain a more stable power generation amount in a speed range around 60 km / h compared to the tire assembly 1.

[0076] The behavior of the second unit 4A and the second unit 4B when the tire assembly 1X rotates is similar to the behavior of the second unit 4 shown in FIG. 7B . As described above, power generation by the second unit 4 is primarily due to changes in the radial acceleration (or centrifugal force) occurring in the tire 2. In the second unit 4B, which has a weight member 41B with a larger mass, a larger radial acceleration is applied to the power generator 10X, so the true contact area is generally more likely to change. In addition, as the natural frequency of the second unit 4B decreases, the true contact area changes more actively in the relatively low speed range (e.g., 60 km / h to 80 km / h) within the high-speed range. However, at relatively high speeds within the high-speed range (e.g., 80 km / h or higher), tracking performance deteriorates and the true contact area is less likely to change, so the speed range in which power generation peaks is 60 km / h to 80 km / h. As a result, even with a second unit having the same structure, if the mass of the weight member is increased, it is possible to adjust the speed range at which the amount of power generated peaks to a lower speed. Conversely, if the mass of the weight member is decreased, the speed range at which the amount of power generated peaks shifts to a higher speed.

[0077] According to the inventors' investigations, in order for the power generation amount of the second unit 4A to peak in the speed range of 80 km / h or higher and the power generation amount of the second unit 4B to peak in the speed range of 60 km / h to 80 km / h, it is preferable that 1.5≦(M4 / M3)≦8. This makes it possible to stabilize the power generation amount of the entire tire assembly 1X over a wider speed range and improve the V-P characteristics of the tire assembly 1X. Note that the dimensions of each component of the power generation body 10X are the same for the second unit 4A and the second unit 4B.

[0078] D. Fourth Embodiment Figure 12 is a longitudinal cross-sectional view of a tire assembly 1Y according to a fourth embodiment. The tire assembly 1Y of this embodiment differs from the tire assembly 1 in that it includes one first unit 3, a second unit 4C, and a second unit 4D. The following description of the tire assembly 1Y will focus on the differences from the tire assembly 1, and elements that share a configuration with the tire assembly 1 will be denoted by the same reference numerals and will not be described again.

[0079] The second unit 4C has a power generator 10Y, a weight member 41Y, and a tape 42Y. These have the same functions as the power generator 10B, weight member 41, and tape 42 of the second unit 4, respectively, and are assembled in the same manner as the second unit 4. The second unit 4D has a power generator 10Z, a weight member 41Z, and a tape 42Y. These also have the same functions as the power generator 10B, weight member 41, and tape 42 of the second unit 4, respectively, and are assembled in the same manner as the second unit 4. The areas of the first and second surfaces of the power generator 10Y are S1, and the areas of the first and second surfaces of the power generator 10Z are S2, where S1 < S2. The weight members 41Y and 41Z are formed to fit the sizes of the power generator 10Y and the power generator 10Z, respectively, and the areas of their main surfaces (surfaces perpendicular to the radial direction of the tire 2) generally correspond to S1 and S2, respectively. The weight members 41Y and 41Z are configured to have the same mass per area. The weights 7G and 7H are appropriately positioned near the second units 4C and 4D, respectively, to correct the mass imbalance of the tire assembly 1Y. Here, in the tire assembly 1Y, a substrate 5 on which one rectifier circuit 5A and two rectifier circuits 5B are mounted is positioned adjacent to the second unit 4C, so the masses of the weights 7G and 7H are set taking into consideration the masses of the substrate 5 and the rectifier circuits 5A and 5B. The rectifier circuit 5A is connected to the power generator 10A, and the rectifier circuit 5B is connected to the power generator 10Y and the power generator 10Z, respectively.

[0080] According to the inventors' investigations, even when the multiple second units include at least one second power generation unit whose first and second surfaces have an area of ​​S1 and at least one second power generation unit whose first and second surfaces have an area of ​​S2, the V-P characteristics of the tire assembly 1Y can be made to be the V-P characteristics shown in Figure 11.

[0081] According to the inventors' investigations, in order for the power generation amount of the second unit 4A to peak at speeds of 80 km / h or higher and the power generation amount of the second unit 4B to peak at speeds of 60 km / h to 80 km / h, it is preferable that 1.5≦(S2 / S1)≦16. In this way, by increasing the area, the power generation amount of the second unit 4B itself can be increased. Furthermore, by reducing the bending rigidity of the power generator 10Z compared to the bending rigidity of the power generator 10Y, the natural frequency of the second unit 4B becomes lower than the natural frequency of the second unit 4A, and the speed range in which the power generation amount of the second unit 4B peaks shifts to the lower speed side. This stabilizes the power generation amount of the entire tire assembly 1Y over a wider speed range, and improves the VP characteristics of the tire assembly 1Y. Note that the areas of the first and second surfaces are not necessarily proportional to the power generation amount, and it is possible to increase the power generation amount when the above areas are less than 8000 mm. 2 ~10,000 mm 2 The inventors have confirmed that the amount of power generation reaches a plateau at about this level. The mass per area of ​​the weight member of the second unit 4C and the second unit 4D is the same.

[0082] 5. Features (1) With the tire assembly 1 according to the above embodiment, the first unit 3 and the second unit 4, which have different deformation mechanisms of the power generating body 10, can ensure the amount of power generated by the tire assembly 1 over a wider speed range. This allows for a stable supply of power to systems and devices connected to the first unit 3 and the second unit 4 while the vehicle 8 equipped with the tire assembly 1 is traveling.

[0083] (2) According to the tire assembly 1 according to the above embodiment, the first unit 3, the second unit 4, and the power supply control circuit 6 are disposed in a distributed manner at N locations (where N≧4) along the circumferential direction of the tire 2. In addition, at least one of these elements is disposed at a position shifted from the locations at which the inner surface 200 is divided into N equal intervals along the circumferential direction. This allows the first component of the RFV to be distributed into Nth-order components, and the Nth-order peak of the RFV to be alleviated, thereby suppressing the generation of vibrations and noise caused by incorporating the first unit 3, the second unit 4, the power supply control circuit 6, etc. into the tire 2.

[0084] (3) According to the tire assembly 1 according to the above embodiment, the mass difference between the first unit 3, the second unit 4, and the power supply control circuit 6, which are disposed in N locations, is reduced by the weights 7A and 7B. This makes it possible to suppress an increase in the RFV of the tire assembly 1. Furthermore, by disposing the rectifier circuits 5A and 5B near the second unit 4, which has the smallest mass among the first unit 3, the second unit 4, and the power supply control circuit 6, the mass difference can be further reduced. In other words, the rectifier circuits 5A and 5B can function as weights, thereby further suppressing an increase in the RFV of the tire assembly 1. Furthermore, if the rectifier circuits 5A and 5B were disposed near the first unit 3, more weights would be required to reduce the mass difference with the second unit 4, which would increase the mass of the entire tire assembly 1. Therefore, disposing the rectifier circuits 5A and 5B near the second unit 4, which has a relatively small mass, also helps to suppress an increase in the mass of the tire assembly 1 as a whole.

[0085] (4) In the tire assembly 1 according to the above embodiment, the mass per pseudo mass point is set to 30 g or less if the tire 2 is for a passenger car, and 40 g or less if the tire 2 is for a large vehicle such as a truck or bus. This also makes it possible to suppress an increase in the RFV of the tire assembly 1.

[0086] (5) In the tire assembly 1 according to the above embodiment, the presser member 30 is made primarily of a composite material of rubber and carbon fiber. This allows the presser member 30 to be lighter in mass while maintaining tensile strength comparable to that of a presser member 30 made primarily of rubber.

[0087] (6) Tire assemblies 1W to 1Y according to the above embodiments can generate more stable power even in a speed range of around 60 km / h (e.g., 50 km / h to 80 km / h) where the amount of power generation is likely to decrease, compared to tire assembly 1. Furthermore, tire assemblies 1W to 1Y can achieve the effects described in (1) to (5) similar to tire assembly 1.

[0088] 6. Modifications Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0089] (1) The number of first units 3 and second units 4 is not limited to those in the above embodiment and can be changed as appropriate. That is, it is sufficient for the tire assembly 1 to include at least one first unit 3 and one second unit 4. For example, as in the tire assembly 1A shown in FIG. 13 , a plurality of first units 3 and a plurality of second units 4 may be arranged along the width direction of the inner surface 200 (a direction parallel to the central axis A1). The first units 3 and the second units may be arranged at the same circumferential position on the inner surface 200. Furthermore, the tire assembly 1W includes a plurality of first units, and the plurality of first power generation body units include at least one first power generation body unit having a weight member with a mass M1 arranged between the power generation body and the presser member, and at least one first power generation body unit having a weight member with a mass M2 arranged between the power generation body and the presser member, where M1 > M2. Tire assembly 1X includes a plurality of second power generation units, and the plurality of second power generation units include at least one second power generation unit having a weight member with a mass M3 and at least one second power generation unit having a weight member with a mass M4, where M3 < M4. Tire assembly 1Y includes a plurality of second power generation units, and the plurality of second power generation units include at least one second power generation unit whose first and second surfaces have areas S1 and at least one second power generation unit whose first and second surfaces have areas S2, where S1 < S2.

[0090] (2) The configurations of the rectifier circuits 5A and 5B and the power supply control circuit 6 are not limited to those described in the above embodiment. For example, at least one of the rectifier circuits 5A and 5B may be mounted on the same board as the power supply control circuit 6. Furthermore, the power supply control circuit 6 may be configured with multiple boards, each divided into different functions (such as controlling the device on / off, controlling the current supply, and storing electricity). The multiple boards may form a single pseudo-mass point, or may be arranged to form two or more pseudo-mass points. Furthermore, the devices included in the system 9 may be arranged on the inner surface 200 independently of the rectifier circuits 5A and 5B and the power supply control circuit 6. In other words, the rectifier circuits 5A and 5B, the power supply control circuit 6, and the devices included in the system 9 may be implemented in any configuration. Furthermore, the elements that form a single pseudo-mass point may be combined as appropriate.

[0091] (3) The first electrode 112 may be formed by weaving conductive fibers into a fabric. The fibers may be, for example, flexible Cu wires or stainless steel wires. Furthermore, the first surface 110 may be formed by coating the outer circumferential surface of the fibers with a first insulating film 111. Similarly, the second electrode 122 may be formed by weaving conductive fibers into a fabric, and the second surface 120 may be formed by coating the outer circumferential surface of the fibers with a second insulating film 121. The fibers may be, for example, flexible Cu wires or stainless steel wires.

[0092] (4) In the first unit 3 and the second unit 4 of the above embodiment, the weight members 31 and 41 are disposed outside the tapes 32 and 42, respectively. However, the weight members 31 and 41 may be disposed inside the tapes 32 and 42, respectively. Furthermore, the tapes 32 and 42 may be replaced with other members, such as bag-shaped members. This also applies to the first unit 3A, the first unit 3B, and the second units 4A to 4D of the above embodiment.

[0093] (5) The control device 80 does not have to be a computer built into or installed in the vehicle 8. The control device 80 may be a portable information processing terminal such as a smartphone, a tablet, or a laptop computer.

[0094] (6) The first unit 3, the second unit 4, the rectifier circuits 5A and 5B, and the power supply control circuit 6 may be disposed in two to three locations, five locations, or seven or more locations along the circumferential direction of the tire 2. Furthermore, the rectifier circuits 5A and 5B and the power supply control circuit 6 may be omitted as appropriate. This also applies to tire assemblies 1W to 1Y.

[0095] (7) The weight member 31 of the first unit 3 may be omitted.

[0096] (8) In the above embodiment, the mass per area of ​​the weight member is the same for the second unit 4C and the second unit 4D, but the mass per area of ​​the weight member may be different. That is, the VP characteristics of the tire assembly 1Y may be adjusted by making the mass per area of ​​the weight member different for the second unit 4C and the second unit 4D in addition to making the areas of the first surface and the second surface different.

[0097] The following describes experiments conducted by the inventors and their results. However, the present invention is not limited to these. <Experiment 1> As in the first embodiment, a tire assembly 1B (Example) was prepared, including two first units, one second unit, a rectifier circuit, and a power supply control circuit. An air pressure sensor, which operates by receiving power from the first and second units, was connected to the power supply control circuit. The air pressure sensor was configured to be wirelessly connected to an external device 93 (a general-purpose computer) when its power was ON. Furthermore, a tire assembly 1C (Comparative Example) was also prepared, which had the same configuration as tire assembly 1B except that it did not include the second unit. The same wheels 71 were attached to these tire assemblies 1B and 1C, and the same air pressure was applied to each. The tire assemblies 1B and 1C with the wheels 71 were each attached to a rotating shaft 92 of an experimental apparatus as shown in FIG. 14, and rotated on a rotating drum 91 at speeds equivalent to 20 km / h to 80 km / h under the same wheel load. While tire assemblies 1B and 1C were rotating, the external device 93 was used to check whether each air pressure sensor was activated and operating (i.e., whether there was wireless communication from the air pressure sensors). The time intervals between wireless communications by the air pressure sensors were also measured. The time intervals between wireless communications by the air pressure sensors correspond to the time intervals required for a certain amount of power to be stored in the power supply control circuit.

[0098] <Result 1> For tire assembly 1B, the time required to confirm activation of the air pressure sensor was similar in the speed range equivalent to 60 km / h to 80 km / h as in the speed range equivalent to 20 km / h to 60 km / h. It was confirmed that the air pressure sensor continued to operate stably throughout the entire speed range equivalent to 20 km / h to 80 km / h for tire assembly 1B. On the other hand, for tire assembly 1C, no problems were found with activation and operation of the air pressure sensor in the low speed range, but the time required to confirm activation of the air pressure sensor increased as the speed approached a speed equivalent to 60 km / h. Furthermore, activation of the air pressure sensor could not be confirmed within the expected time at speeds above 60 km / h. This confirmed that the tire assembly according to the above embodiment is capable of generating electricity over a wider speed range.

[0099] <Experiment 2> A tire assembly in which a first unit according to the above embodiment was fixed to the inner surface of the tire was prepared and designated a reference tire assembly. This reference tire assembly was assembled into an experimental apparatus as shown in FIG. 14 and rotated under specified air pressure and wheel load conditions. It was confirmed that the power generation capacity of the first unit peaked at a speed of 30 km / h. This first unit included a square power generator with a side length of 35 mm, a weight member with a mass of 2.7 g, and a pressure member. Next, tire assemblies were prepared that had the same configuration of the power generator, pressure member, and tire, but with the weight member's mass set to 1 / 3 (0.9 g) and 1 / 4 (0.675 g) times that of the reference tire assembly, respectively, and a tire assembly in which the weight member was omitted. Each tire assemblies was assembled into the experimental apparatus and rotated at speeds of 20 km / h to 100 km / h under the same conditions as the reference tire assembly, and the power generation capacity of the first unit of each tire assembly was measured.

[0100] <Result 2> The graph of the amount of power generated by the first unit of each tire assembly is shown in Figure 15. As can be seen from the graph in Figure 15, the tire assembly in which the mass of the weight member was one-third that of the reference tire assembly exhibited a peak in the amount of power generated near 60 km / h, while the tire assembly in which the mass of the weight member was one-quarter that of the reference tire assembly exhibited a peak in the amount of power generated near 50 km / h. This confirms that when the mass of the weight member is set to one-third or less of the mass of the weight member of the reference tire assembly, the peak in the amount of power generated by the first unit shifts toward higher speeds (50 km / h to 60 km / h). Furthermore, it was confirmed that the amount of power generated near 60 km / h for these tire assemblies exceeded that of the reference tire assembly. Note that the tire assemblies in which the weight member was omitted exhibited an overall decrease in the amount of power generated compared to the reference tire assembly, and no shift in the peak in power generation toward higher speeds was observed. This is thought to be because the absence of the weight member reduces the bending rigidity of the first unit, leading to a decrease in the natural frequency. Furthermore, the absence of the weight member makes it difficult for the deformation of the pressing member to be transmitted to the generator, which is thought to be why the amount of power generated is reduced.

[0101] Experiment 3: A tire assembly was prepared in which the second unit according to the above embodiment was fixed to the inner surface of the tire. This tire assembly was designated the reference tire assembly. This reference tire assembly was installed in an experimental device such as that shown in FIG. 14 and rotated under specified air pressure and wheel load conditions. It was confirmed that the power generation capacity of the second unit peaked at speeds of 100 km / h or higher. This second unit included a square power generator with a side length of 25 mm, a weight member with a mass of 1.4 g, and tape. Next, two tire assemblies were prepared: one with a power generator side length of 35 mm and a weight member with a mass of 2.7 g, and another with a power generator side length of 25 mm and a weight member with a mass of 6.4 g, all of which had the same tire and tape configuration. In each tire assembly, the weight member had the same square shape as the power generator, and the same side length as the power generator. In other words, the weight member's mass per area was the same for all tire assemblies. Each tire assembly was assembled into the above-mentioned experimental device and rotated at 20 km / h to 100 km / h under the same conditions as the reference tire assembly, and the amount of power generated by the second unit of each tire assembly was measured.

[0102] <Result 3> The graph of the amount of power generated by the second unit of each tire assembly is shown in Figure 16. As can be seen from the graph in Figure 16, the tire assemblies with a weight member mass of 2.7 g and the tire assemblies with a weight member mass of 6.4 g both had higher overall power generation amounts than the reference tire assembly. Furthermore, for the tire assemblies with a weight member mass of 2.7 g, the slope of the power generation amount versus speed was larger in speed ranges slower than the slope of the reference tire in the same speed range. This confirmed that the peak power generation amount for the tire assemblies with a weight member mass of 2.7 g shifted to a lower speed range compared to the reference tire assembly. Furthermore, for the tire assemblies with a weight member mass of 6.4 g, the slope was larger in lower speed ranges than the slope of the tire assemblies with a weight member mass of 2.7 g. From this, it was confirmed that it can be said that the peak of the amount of power generation shifts to a lower speed range in the tire assembly in which the mass of the weight member is 6.4 g.

[0103] REFERENCE SIGNS LIST 1, 1A to 1C, 1W to 1Y Tire assembly 2 Tire 3, 3A, 3B First power generating unit 4, 4A, 4B, 4C, 4D Second power generating unit 8 Vehicle 9 In-vehicle system 10, 10A, 10B, 10W, 10X, 10Y, 10Z Power generating unit 31 Pressing member

Claims

1. A tire mounted on a vehicle, one or more first power generation units, and one or more second power generation units different from the first power generation units, wherein the first power generation unit has a power generation body arranged on the inner surface of the tire, and a pressing member fixed to the inner surface of the tire on both sides of the power generation body so as to straddle the power generation body along the circumferential direction of the tire, the pressing member being deformable in response to deformation of the tire, wherein the second power generation unit has a power generation body fixed to the inner surface of the tire, and a weight member placed on the power generation body from the side opposite the inner surface, sandwiching the power generation body therebetween, wherein the power generation body has a first member having a first insulating film forming a first surface, and a second member having a second insulating film facing the first surface and forming a second surface in contact with the first surface, wherein the first member and the second member are configured such that a real contact area between the first surface and the second surface changes in response to a force applied to the first member and the second member, the first insulating film and the second insulating film are configured such that one is positively charged and the other is negatively charged as a result of the change in the real contact area.

2. A tire assembly as described in claim 1, comprising a plurality of said first power generation body units, said plurality of first power generation body units including at least one first power generation body unit having a weight member of mass M1 arranged between said power generation body and said pressure member, and at least one first power generation body unit having a weight member of mass M2 arranged between said power generation body and said pressure member, wherein M1>M2.

3. A tire assembly as described in claim 1 or 2, comprising a plurality of said second power generating units, said plurality of second power generating units including at least one second power generating unit having a weight member of mass M3 and at least one second power generating unit having a weight member of mass M4, wherein M3<M4.

4. A tire assembly as described in claim 1 or 2, comprising a plurality of the second power generation units, the plurality of second power generation units including at least one second power generation unit having an area of ​​the first surface and the second surface S1 and at least one second power generation unit having an area of ​​the first surface and the second surface S2, and S1 < S2.

5. The tire assembly according to claim 1, further comprising: one or more circuits that receive power from each of the first power generating unit and the second power generating unit and are connected to an external computer so as to be capable of data communication.

6. The tire assembly according to claim 5, wherein the first power generating unit, the second power generating unit, and the circuit are disposed in a dispersed manner at four or more locations along the circumferential direction of the tire.

7. The tire assembly according to claim 5, wherein the first power generating unit, the second power generating unit, and the circuit are distributed at six or less locations along the circumferential direction of the tire.

8. The tire assembly according to claim 6 or 7, further comprising: a weight that reduces a mass difference between the first power generating unit, the second power generating unit, and the circuit, the first power generating unit and the second power generating unit being disposed in a distributed manner.

9. A tire assembly as described in claim 6 or 7, wherein at least one of the first power generation unit, the second power generation unit and the circuit is positioned at a position shifted from a point at which the tire is divided into N equal intervals along the circumferential direction.

10. The tire assembly according to claim 1 or 2, wherein the pressing member includes at least one of rubber, a thermoplastic elastomer, a thermoplastic resin, and a thermosetting resin.

11. The tire assembly according to claim 10, wherein the pressing member includes a composite material of rubber and carbon fiber.

12. The tire assembly of claim 5, wherein the computer is configured to monitor at least one of the tire pressure, the internal temperature of the tire, and the rotational speed of the tire.

13. A method for manufacturing a tire assembly comprising: a tire to be mounted on a vehicle; and a power generator comprising a first member having a first insulating film forming a first surface, and a second member having a second insulating film forming a second surface facing the first surface and in contact with the first surface, the first member and the second member being configured such that a real contact area between the first surface and the second surface changes in response to a force applied to the first member and the second member, and the first insulating film and the second insulating film are configured such that one becomes positively charged and the other becomes negatively charged as the real contact area changes, the method comprising: preparing the tire; preparing at least three power generators including a first power generator, a second power generator, and a third power generator; and arranging each of the at least three power generators on the inner surface of the tire; and arranging each of the at least three power generators on the inner surface of the tire. a pressure member deformable in response to deformation of the tire is fixed to the inner surface of the tire on both sides of the first power generator so as to straddle the first power generator along the circumferential direction of the tire, and a first weight member having a first mass is disposed between the first power generator and the pressure member, so that the amount of power generated by the first power generator peaks in a first speed region of the tire rotational speed; a second weight member having a second mass is placed on the power generator from the side opposite the inner surface, sandwiching the power generator therebetween, so that the amount of power generated by the second power generator peaks in a second speed region of the tire rotational speed; a second weight member having a second mass is placed on the power generator from the side opposite the inner surface, sandwiching the power generator, and a second weight member having a third mass smaller than the first mass is disposed between the third power generator and the second pressure member, so that the amount of power generated by the third power generator peaks in a third speed region of the tire rotational speed; or and overlapping a fourth weight member having a fourth mass greater than the second mass with the third power generating body from a side opposite the inner surface, with the third power generating body sandwiched therebetween, so that an amount of power generated by the third power generating body reaches a peak in a third speed range of the rotational speed of the tire,the first speed region is a region slower than the third speed region, and the third speed region is a region slower than the second speed region.

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