Power generator

Abstract

The present invention provides a highly durable power generator. The power generator comprises a first component, a second component, and a packaging body. The first component has a first insulating film forming a first surface. The second component has a second insulating film forming a second surface that is opposite to and in contact with the first surface. The packaging body seals the first component and the second component. The first component and the second component are configured so that the actual contact area between the first surface and the second surface changes according to the pressure applied to the first component and the second component, and the first insulating film and the second insulating film are configured so that one is positively charged and the other is negatively charged as the actual contact area changes.

Description

Technical Field

[0001] The present invention relates to an electric power generator. Background Art

[0002] Japanese Patent Application Publication No. 2018-191454 (Patent Document 1) discloses a triboelectric generator. In the generator of Patent Document 1, the actual contact area between the opposing first and second insulating films changes depending on the pressure applied to the generator, causing the first and second insulating films to be charged to opposite polarities.

[0003] Japanese Patent Application Publication No. 2016-088473 (Patent Document 2) discloses a tire assembly in which a generator is incorporated into a tire. The generator generates voltage through deformation of the tire. The generator includes a fixing portion that maintains a predetermined distance between a first electrode structure and a second electrode structure. An electronic device is embedded within the fixing portion, thereby protecting the electronic device from the environmental influences inside the tire.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-191454

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2016-088473 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] When a generator utilizing frictional electrification is incorporated into a tire, as in Patent Document 2, tire deformation must be transmitted to the generator. Furthermore, the generator may be subject to impact from the road surface or to sudden temperature fluctuations within the tire. Therefore, it is desirable to develop a generator that exhibits sufficient durability even in such environments. This is not limited to cases where a generator utilizing frictional electrification is incorporated into a tire; it is also applicable to environments where the generator is subject to impact or significant temperature fluctuations.

[0010] An object of the present invention is to provide a highly durable power generator.

[0011] Means for solving problems

[0012] The power generator according to the first aspect of the present invention comprises a first component, a second component, and a packaging body. The first component has a first insulating film forming a first surface. The second component has a second insulating film forming a second surface that is opposite to and in contact with the first surface. The packaging body seals the first component and the second component. The first component and the second component are configured such that the actual contact area between the first surface and the second surface changes in accordance with the pressure applied to the first component and the second component, 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 actual contact area changes.

[0013] The power generator according to a second aspect of the present invention is the power generator according to the first aspect, wherein the packaging body is made of rubber or an elastomer.

[0014] The power generator according to a third aspect of the present invention is the power generator according to the first aspect or the second aspect, wherein the packaging body is made of butyl rubber.

[0015] The power generator according to a fourth aspect of the present invention is the power generator according to any one of the first to third aspects, further comprising a cushioning material disposed on the side of the first member opposite to the first surface, the cushioning material being sealed by the packaging body.

[0016] The power generator according to the fifth aspect of the present invention is like the power generator according to the fourth aspect, wherein the power generator further comprises a plate-shaped weight, which is arranged between the above-mentioned cushioning material and the above-mentioned first component to form a pressing surface for pressing the above-mentioned first component, and the weight is sealed by the above-mentioned packaging body.

[0017] The power generator according to a sixth aspect of the present invention is the power generator according to the fifth aspect, wherein the weight is made of a hard material.

[0018] The power generator according to the seventh aspect of the present invention is the power generator according to any one of the first to sixth aspects, wherein the first component further has a first electrode on the back side of the first surface configured to be in contact with the first insulating film, and the second component further has a second electrode on the back side of the second surface configured to be in contact with the second insulating film, and the first electrode and the second electrode are made of a flexible material.

[0019] A tire assembly according to an eighth aspect of the present invention comprises: the power generator according to the seventh aspect; a tire mounted on a wheel; and an electronic device that receives power output from the power generator. The power generator is disposed inside the tire.

[0020] A tire assembly according to a ninth aspect of the present invention is the tire assembly according to the eighth aspect, further comprising a battery for storing the power output by the power generator, wherein the electronic device receives power stored in the battery.

[0021] The tire assembly according to a tenth aspect of the present invention is the tire assembly according to the eighth aspect or the ninth aspect, wherein the electronic device includes a communication device capable of performing data communication with an external device.

[0022] A tire monitoring system according to an eleventh aspect of the present invention comprises: the tire assembly according to the tenth aspect; and an external control device capable of communicating data with the communication device. The communication device transmits at least one output data of a voltage and a current output by the generator, and a physical quantity based on at least one of the voltage and the current, to the external control device, and the external control device monitors information related to the tire based on the output data received from the communication device.

[0023] The tire monitoring system of the 12th aspect of the present invention is like the tire monitoring system of the 11th aspect, wherein the information related to the above-mentioned tire includes at least one of information related to the rotation speed of the above-mentioned tire, information related to the wear of the above-mentioned tire, and information related to the state of the road surface on which the vehicle equipped with the above-mentioned tire is traveling.

[0024] A tire monitoring system according to a thirteenth aspect of the present invention is the tire monitoring system according to the eleventh aspect or the twelfth aspect, wherein the external control device is mounted on a vehicle including the tire assembly.

[0025] A tire monitoring method according to a fourteenth aspect of the present invention includes the following.

[0026] A vehicle equipped with the tire assembly according to any one of the eighth to tenth aspects is prepared.

[0027] During the travel of the vehicle, at least one output data of a voltage and a current outputted by the power generator and a physical quantity based on at least one of the voltage and the current is collected.

[0028] Monitor information related to the tire based on the collected output data.

[0029] Effects of the Invention

[0030] According to the present invention, a highly durable power generator is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic cross-sectional view of a power generator according to one embodiment of the present invention.

[0032] Figure 2 It is a diagram showing changes in the power generator.

[0033] Figure 3 FIG. 1 is a schematic cross-sectional view of a sensor module according to an embodiment.

[0034] Figure 4 This is a perspective view of a package body according to one embodiment.

[0035] Figure 5 This is a schematic cross-sectional view of a tire assembly according to one embodiment.

[0036] Figure 6 This is a diagram showing the overall configuration of a monitoring system according to one embodiment.

[0037] Figure 7 This is a block diagram showing the electrical configuration of the monitoring system.

[0038] Figure 8A It is a schematic cross-sectional view of a power generator according to a modified example.

[0039] Figure 8B It is a schematic cross-sectional view of a power generator according to another modified example.

[0040] Figure 8C It is a schematic cross-sectional view of a power generator according to yet another modified example.

[0041] Figure 9 It is a schematic cross-sectional view of a tire assembly according to a modified example.

[0042] Figure 10A This is a diagram showing the configuration of an experimental device using tires.

[0043] Figure 10B It is a graph of the output voltage of the power generator of the Example. DETAILED DESCRIPTION

[0044] Hereinafter, a power generator according to one embodiment of the present invention, a tire assembly including the power generator, and a tire monitoring system and a monitoring method using the tire assembly will be described with reference to the accompanying drawings.

[0045] <1. Structure of the generator>

[0046] Figure 1 1 is a cross-sectional view showing the structure of a power generator 1 according to an embodiment of the present invention. Figure 1 As shown, the power generator 1 includes a first component 10, a second component 20, and a package 50. The first component 10 and the second component 20 are housed in the package 50. It should be noted that the direction of use of the power generator 1 is not limited to Figure 1 direction shown.

[0047] The first component 10 comprises a first substrate 130, a first electrode 120, and a first insulating film 110, each of which is stacked sequentially from the outside toward the inside of the generator 1. The first substrate 130 is made of a flexible or viscoelastic material, such as resin, rubber, or elastomer, to enable deformation when subjected to external forces. In this embodiment, the first substrate 130 is made of silicone rubber. A large number of irregularities are formed on the surface of the first substrate 130 that contacts the first electrode 120. As a result, irregularities corresponding to those of the first substrate 130 are reproduced on the first surface 100 formed by the first insulating film 110 via the first electrode 120.

[0048] The first electrode 120 is used to extract the charge generated in the first insulating film 110 to the outside of the power generator 1. It is located on the back side of the first surface 100, in contact with the first insulating film 110. The first electrode 120 is composed of a film of a conductive material, such as Ag or Cu. The first electrode 120 is flexible and can deform in response to the deformation of the first substrate 130. Furthermore, the surface of the first electrode 120 in contact with the first insulating film 110 reproduces the irregularities of the first substrate 130.

[0049] The first insulating film 110 is a flexible film made of an insulator. The first insulating film 110 forms the first surface 100. Concavities and convexities corresponding to the concavities and convexities of the first substrate 130 are formed on the first surface 100 via the first substrate 130. The first surface 100 faces and contacts the second surface 200 formed by the second insulating film 210, described later. When the actual contact area between the first surface 100 and the second surface 200, or the actual contact area, changes depending on the pressure applied to the power generator 1, the first insulating film 110 becomes charged with an opposite polarity to that of the second insulating film 210. Specifically, when the second insulating film 210 is positively charged, the first insulating film 110 becomes negatively charged. Conversely, when the second insulating film 210 is negatively charged, the first insulating film 110 becomes positively charged.

[0050] The ten-point average roughness of the first surface 100 is preferably 100 μm or more and 2 mm or less. The ten-point average roughness is measured in accordance with JIS B 0601:2001.

[0051] It should be noted that when the first surface 100 and the second surface 200 are “in contact”, it is sufficient that the first surface 100 and the second surface 200 are partially in contact, and there may be a portion where the first surface 100 and the second surface 200 are not in contact.

[0052] The second component 20 comprises a second substrate 230, a second electrode 220, and a second insulating film 210, each of which is stacked sequentially from the outside toward the inside of the power generator 1. The second substrate 230 is made of a flexible or viscoelastic material, such as resin, rubber, or elastomer, to enable deformation when subjected to external forces. In this embodiment, the second substrate 230 is made of silicone rubber. A large number of irregularities are formed on the surface of the second substrate 230 that contacts the second electrode 220. As a result, irregularities corresponding to those of the second substrate 230 are reproduced on the second surface 200 formed by the second insulating film 210 via the second electrode 220.

[0053] The second electrode 220 is used to extract the charge generated in the second insulating film 210 to the outside of the power generator 1. It is located on the back side of the second surface 200, in contact with the second insulating film 210. The second electrode 220 is composed of a film of a conductive material, such as Ag or Cu. The second electrode 220 is flexible and can deform in response to the deformation of the second substrate 230. Furthermore, the second electrode 220 reproduces the unevenness of the second substrate 230 on the surface in contact with the second insulating film 210.

[0054] The second insulating film 210 is a flexible film made of an insulator different from that of the first insulating film 110. The second insulating film 210 forms the second surface 200. Concavities and convexities corresponding to the concavities and convexities of the second substrate 230 are formed on the second surface 200 via the second substrate 230. The second surface 200 faces and contacts the first surface 100 formed by the first insulating film 110. When the actual contact area between the first surface 100 and the second surface 200 changes depending on the pressure applied to the power generator 1, the second insulating film 210 becomes charged with an opposite polarity to that of the first insulating film 110. That is, when the first insulating film 110 is positively charged, the second insulating film 210 becomes negatively charged. Conversely, when the first insulating film 110 is negatively charged, the second insulating film 210 becomes positively charged.

[0055] The ten-point average roughness of the second surface 200 is preferably 100 μm or more and 2 mm or less. The ten-point average roughness is measured in accordance with JIS B 0601:2001.

[0056] At least one of the thickness W1 of the first insulating film 110 and the thickness W2 of the second insulating film 210 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.

[0057] The material constituting the first insulating film 110 and the second insulating film 210 can be selected from, for example, diamond-like carbon (DLC), perfluoropolyether, polymethyl methacrylate, nylon, polyvinyl alcohol, polyester, polyisobutylene, polyurethane (PU), polyethylene terephthalate, polyvinyl butyral, polychloroprene, natural rubber, polyacrylonitrile, polyphenyl carbonate, chlorinated polyether, polyvinylidene chloride, polystyrene, polyethylene, polypropylene, polyimide, polyvinyl chloride, polydimethylsiloxane, polytetrafluoroethylene, tetrafluoroethylene and hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and a group consisting of materials with other fluorinated carbon organic substances as the main components.

[0058] From the perspective of minimizing wear of the insulating films due to frictional contact between the first insulating film 110 and the second insulating film 210, DLC, which has a high hardness and low coefficient of friction, and materials primarily composed of organic fluorinated carbons with high lubricity are preferred. Furthermore, from the perspective of increasing the electromotive force of the generator 1, materials further away in the charging sequence are preferred within this group. It should be noted that either the first insulating film 110 or the second insulating film 210 can be positively charged or negatively charged.

[0059] In this embodiment, the first insulating film 110 is made of FEP and the second insulating film 210 is made of PU. Therefore, in this embodiment, the first insulating film 110 is a negatively charged insulating film and the second insulating film 210 is a positively charged insulating film.

[0060] The first insulating film 110 and the second insulating film 210 are charged by the following operation. Figure 1 As shown, both the first surface 100 and the second surface 200 have concavo-convex portions, and even when no external pressure is applied to the power generator 1, they are not completely separated, and portions in contact with each other remain. At this time, the distance between the average surface of the first surface 100 and the average surface of the second surface 200 (average surface spacing) is relatively large, which is equivalent to the case where the actual contact area between the first surface 100 and the second surface 200 is relatively small. Next, when pressure is applied to the power generator 1 in such a way that the first insulating film 110 and the second insulating film 210 are closer, the shapes of the first surface 100 and the second surface 200 change, the concavo-convex portions become slightly flattened, and the average surface spacing decreases ( Figure 2 ). In other words, the actual contact area increases. Furthermore, when the pressure applied to the power generator 1 is removed, the first insulating film 110 and the second insulating film 210 separate again, and the average interplanar separation increases. In other words, the actual contact area decreases. Thus, when the actual contact area changes, the charge of the first insulating film 110 and the second insulating film 210 increases compared to the initial state, inducing more charge in the first electrode 120 and the second electrode 220.

[0061] It should be noted that the actual contact area can also be changed by causing the first insulating film 110 and the second insulating film 210 to move relative to each other in the planar direction. Therefore, the force applied to the power generator 1 not only contributes to power generation by the power generator 1 by increasing or decreasing the average planar spacing, but also contributes to power generation by the power generator 1 by causing the first insulating film 110 and the second insulating film 210 to slide relative to each other in the planar direction.

[0062] The power generator 1 may further include a weight 40. The weight 40 is arranged on the side of the first component 10 opposite to the first surface 100, and has a pressing surface 41 that contacts the surface of the first substrate 130 on the side opposite to the first electrode 120. The weight 40 is preferably made of a hard material and formed into a flexible flat plate. The weight 40 applies surface pressure to the first component 10 and the second component 20 in the direction in which the first insulating film 110 and the second insulating film 210 approach each other due to its mass. As a result, the average surface spacing between the first surface 100 and the second surface 200 changes more evenly. In addition, the contact portion and the non-contact portion of the first surface 100 and the second surface 200 are formed more evenly, and the first insulating film 110 and the second insulating film 210 are effectively charged without unevenness.

[0063] As will be described later, the generator 1 can be arranged inside a tire 70 mounted on a vehicle 6 and used to convert the expansion and contraction of the tire 70 into electricity. In one embodiment, the generator 1 is arranged inside the tread portion 700 of the tire 70 with the first component 10 facing radially inward and the second component 20 facing radially outward (see FIG. Figure 5 Generator 1 rotates on the road surface along with tire 70 and, when closest to the road surface, is subjected to impact from the road surface. This causes first component 10 to float away from second component 20, maintaining a minimal contact area between first surface 100 and second surface 200 for a relatively long period of time, thereby reducing the amount of power generated by generator 1. Weight 40 promotes uniform charging of first insulating film 110 and second insulating film 210, suppresses lifting of first component 10 due to impact from the road surface, and thereby increases the amount of power generated by generator 1.

[0064] The weight 40 is preferably formed so that the pressing surface 41 overlaps the entire first surface 100 and the second surface 200. The pressing surface 41 is preferably uniform as a whole, but may not necessarily be formed by a smooth surface. For example, it may be the surface of a flat plate with punched holes formed throughout, or the surface of a mesh-like flat plate.

[0065] The material constituting the weight 40, and the mass, density, and thickness of the weight 40 are not particularly limited and may be appropriately selected according to the embodiment of the power generator 1. Examples of the material constituting the weight 40 include metals. In this embodiment, the weight 40 is made of stainless steel (SUS).

[0066] The generator 1 may further include a cushioning material 30. The cushioning material 30 is positioned on the side opposite the first component 10, with the weight 40 interposed therebetween. When the first component 10 and the second component 20 are subjected to a force in the direction in which the first surface 100 and the second surface 200 approach each other, the cushioning material 30 mitigates this force, thereby ensuring sufficient power generation by the generator 1. For example, consider the generator 1 being assembled to a tire 70 and rotating along with the tire 70. The first component 10 and the second component 20 are compressed by the force due to the internal pressure of the tire 70 and the centrifugal force due to the rotation of the tire 70. It is believed that in such an environment, once the first surface 100 and the second surface 200 approach each other, it is difficult for them to move away again, resulting in insufficient change in the actual contact area, and consequently, reduced power generation by the generator 1. Therefore, it is preferable that the cushioning material 30 be positioned outside the first component 10 and the second component 20, in the direction in which they are subjected to the main pressure, to ensure that there is room for change in the actual contact area.

[0067] The material constituting the cushioning material 30 can be a material having a void structure so that its volume can be easily changed. Examples of materials having a void structure include non-woven fabrics, sponges, resins, rubbers, or elastomer foams. The non-woven fabric can be composed of a single or two or more materials selected from polyamide, polyethylene, acrylonitrile fiber, rayon, polyester, polypropylene, aramid, vinylon, and polylactic acid. In addition, the non-woven fabric can be a felt made of wool. Examples of resin, rubber, or elastomer foams include materials selected from polyurethane, silicone, acrylic resin, melamine, ethylene vinyl acetate copolymer (EVA), polypropylene (PP), polyethylene (PE), polystyrene (PS), natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), chloroprene rubber (CR), ethylene-propylene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), and fluororubber (FPM) and the like, wherein a foaming agent is appropriately mixed and vulcanized. A foamed structure of resin, rubber, or elastomer is more preferable than a structure of single cells. As the material constituting the cushioning material 30, wool is preferred for its high heat resistance, while a viscoelastic material such as resin, rubber, or elastomer is preferred for attenuating vibrations caused by the rise and fall of the first component 10. By attenuating the vibrations of the first component 10, not only is the power generation increased, but the timing of the generator 1's initial approach to the road surface and the timing of its initial departure from the road surface are appropriately reflected in the voltage waveform output by the generator 1.

[0068] The package 50 houses and integrates the first component 10, the second component 20, the cushioning material 30, and the weight 40, sealing them to isolate them from water vapor. The package 50 collects the first component 10, the second component 20, the cushioning material 30, and the weight 40 so that they do not escape due to tire rotation. Furthermore, it isolates water vapor generated within the tire 70, limiting its impact on power generation. The package 50 is preferably made of a material with low moisture permeability and sufficient flexibility to adapt to the deformation of the tire 70. Examples of such materials include rubber and elastomers.

[0069] The package body 50 may be configured in any shape as long as it can seal the first component 10 , the second component 20 and other components. Figure 4 This is an example of the structure of the package 50. Figure 4 As shown, the packaging body 50 has a generally square top portion 51, a bottom portion 52 opposite the top portion 51, and four side portions 53 rising between the top portion 51 and the bottom portion 52, and is configured to have an internal space defined by these portions 51 to 53. Furthermore, the bottom portion 52 may have a flange portion 54. The top portion 51, the bottom portion 52, and the side portions 53 may be made of the same material or different materials. In addition, at least a portion of each portion may be integrally molded or bonded using an appropriate adhesive, etc., depending on the material.

[0070] The material constituting the package 50 preferably has high tensile strength. As described above, the internal pressure of the tire 70 and the centrifugal force from its rotation exert compressive forces in the thickness direction on the generator 1 assembled within the tire 70. On the other hand, impacts from the road surface also exert tensile forces in the thickness direction on the generator 1. Therefore, the package 50 is preferably constructed of a material that can withstand these forces. In particular, based on the following assumptions, the tensile strength of the material constituting the package 50 is preferably 3.6 MPa or greater.

[0071] Consider the stress generated on the side surface 53 of the package 50 when a tire 70 (tire assembly 7) with a radius r (m) and an assembled generator 1 is driven at a speed v (km / h). The centrifugal force acting on the cushioning material 30, the weight 40, and the first component 10 is expressed by the mass m (g) of the cushioning material 30, the weight 40, and the first component 10, and is expressed by mv. 2 Now, when the tire 70 has a running speed v of 160 (km / h), a radius r of 0.33 (m), and a mass m of 30 (g), the centrifugal force mv acting on the cushioning material 30, the weight 40, and the first component 10 is 2 / r is approximately 180 (N). Note that, as the running speed v of the tire 70 , the maximum speed of the tire 70 defined by the speed sign of the tire 70 is assumed.

[0072] Here, when the cross-sectional area of one side surface portion 53 of the package body 50 is A (m 2 ), the stress P (MPa) generated on the side surface portion 53 is expressed as (mv 2 / r) / A indicates. Figure 4 In the package 50 shown, when the length of one side of the side portion 53 is represented as L1 (m) and the thickness of the side portion 53 is represented as L2 (m), A = L1 × L2. Now, when the length L1 is 0.05 (m) and the thickness L2 is 0.001 (m), the stress P (MPa) is about 3.6 MPa. Examples of materials with a tensile strength of 3.6 MPa or more include natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), and butyl rubber (IIR). The tensile strength of materials made of these rubbers alone or in combination of two or more is generally 5 MPa to 15 MPa. It should be noted that when the radius r of the tire is smaller than 0.33 (m), the centrifugal force and the stress P are larger than 180 (N) and 3.6 MPa. For example, when r = 0.25 (m), mv 2 / r is about 236 (N), and stress P is about 4.7 (MPa). Therefore, according to the above materials, when applied to tires with small radius, sufficient tensile strength can be ensured while the size of the package 50 remains unchanged.

[0073] <2. Sensor Module Configuration>

[0074] The following describes one embodiment of a sensor module (hereinafter referred to as a module) 8 including a power generator 1. Module 8 is disposed within a tire 70, as described below, for example, to detect information related to tire 70 and output the detection results to, for example, a control device 60 of a vehicle 6. The detection results output by module 8 are utilized in various control systems, such as a tire air pressure monitoring system (TPMS) installed in the vehicle 6. Figure 3 Schematic diagram showing the structure of module 8. Figure 7 The electrical configuration of the module 8 is shown in FIG.

[0075] Generator 1 is electrically connected to a circuit including a battery 80 and an electronic device via first electrode 120 and second electrode 220. Generator 1, battery 80, and the electronic device together constitute module 8. Within module 8, generator 1 can supply power to the electronic device. Furthermore, generator 1 can be used as a sensor by detecting the physical quantity output by generator 1 using other electronic devices. For example, when module 8 is applied to a tire 70, the voltage data output by generator 1 can include information related to the rotational speed of tire 70, information related to tire wear, and information related to the conditions of the road surface on which tire 70 is traveling.

[0076] Module 8 includes a generator 1, a battery 80, and electronic equipment that receives power from the generator 1. The battery 80 and the electronic equipment are electrically connected via a printed circuit board 84. The electronic equipment in this embodiment includes a microcontroller (hereinafter referred to as a microcomputer) 81, a detection device 82, and a communication device 83. The generator 1 is electrically connected to the microcomputer 81 via lead wires 85, 85.

[0077] Microcomputer 81 includes a processor, main memory, and a nonvolatile, rewritable storage device. Programs for controlling the operation of module 8 are written to the storage device of microcomputer 81 and executed by the processor. Microcomputer 81 stores the power output by generator 1 in battery 80 and distributes the stored power to microcomputer 81, detection device 82, and communication device 83 as needed.

[0078] Furthermore, the microcomputer 81 is configured to transmit and receive data with an external control device via a communication device 83. An example of the external control device is the control device 60 of the vehicle 6 described later. The data transmitted from the microcomputer 81 to the control device 60 includes data related to the power output by the generator 1 and data output by the detection device 82.

[0079] The microcomputer 81 detects the voltage or current output by the generator 1 using a detection circuit (not shown). The microcomputer 81 stores the detected voltage or current as time-series data in a storage device. The microcomputer 81 transmits the data stored in the storage device to the control device 60 using the communication device 83 at a predetermined timing. The transmitted data need not be the value detected by the detection circuit itself, but may include data based on a physical quantity of at least one of the voltage and current (e.g., power data) instead of or in addition to the value detected by the detection circuit.

[0080] The detection device 82 is a sensor that detects the state inside the tire 70. The state inside the tire 70 detected by the detection device 82 may be, for example, a value related to air pressure or temperature. The detection device 82 outputs the detected value to the microcomputer 81.

[0081] The communication device 83 includes an antenna and can wirelessly transmit and receive data with an external device. In this embodiment, the external device includes the control device 60 of the vehicle 6 to which the tire assembly 7 is mounted.

[0082] The battery 80, microcomputer 81, detection device 82, communication device 83, and the printed circuit board 84 connecting them are integrally encapsulated with epoxy resin 86. This prevents moisture vapor from within the tire 70 from entering the battery 80 and the electronic devices 81-83, while maintaining the battery 80 and the electronic devices 81-83 secured to the printed circuit board 84. The detection element (not shown) of the detection device 82 can be exposed from the epoxy resin 86 as needed. Furthermore, lead wires 85, 85 extend outside the epoxy resin 86.

[0083] <3-1. Structure of Tire Assembly>

[0084] Hereinafter, the detailed structure of the tire assembly 7 will be described with reference to the accompanying drawings. Figure 6 As shown, tire assemblies 7 are mounted on each wheel of vehicle 6. Vehicle 6 is a four-wheeled vehicle, equipped with a left front wheel FL, a right front wheel FR, a left rear wheel RL, and a right rear wheel RR. Tire assemblies 7a through 7d are mounted on wheels FL, FR, RL, and RR, respectively. While tire assemblies 7a through 7d are mounted on different wheels, they share the same structure and function. Therefore, tire assemblies 7a through 7d will sometimes be referred to as tire assembly 7 without distinguishing them. Tire assembly 7 transmits detection data to control device 60 mounted on vehicle 6.

[0085] Figure 5 : is a schematic partial cross-sectional view of the tire assembly 7. Figure 5 In the figure, the direction from the back side to the front side of the paper, or the direction from the front side to the back side of the paper, is the circumferential direction of the tire assembly 7. The tire assembly 7 includes a tire 70 and a module 8. The tire assembly 7 is mounted on the wheels FL, FR, RL, and RR of the vehicle 6 via wheels 71. A rim 710 is formed on the periphery of the wheel 71.

[0086] The tire 70 is made of an elastic material such as rubber or an elastomer and includes a tread portion 700, a shoulder portion 701, a sidewall portion 702, and a bead portion 703. The tread portion 700 defines the side circumference of the tire assembly 7 and generates friction with the road surface, thereby propelling the vehicle 6 forward. The shoulder portion 701 is adjacent to the tread portion 700 and the sidewall portion 702. The sidewall portion 702 bends to absorb impact from the road surface, thereby flexing. The bead portion 703 incorporates a bead wire (not shown) and is secured to the rim 710.

[0087] Module 8 is disposed on the inner side of tire 70. The portion of module 8 other than generator 1 is fixed near generator 1 and to the inner side of tire 70. The location where the portion of module 8 other than generator 1 is fixed is not particularly limited, and for example, it may be fixed to the tread portion 700, the shoulder portion 701, the sidewall portion 702, or the like.

[0088] The power generator 1 is arranged so that the second member 20 is located radially outside the tire 70 and the first member 10 is located radially inside the tire 70. Figure 5 In the example shown, the package 50 is secured so that its bottom portion 52, including the flange portion 54, contacts the inner surface of the tire 70. There are no particular limitations on the method by which the package 50 is secured to the tire 70, and physical or chemical bonding is possible. It should be noted that the package 50, including the generator 1, is preferably secured to the inner side of the tread 700. However, as long as the vibration of the tire 70 can be utilized to generate electricity, the location of the securement is not limited; for example, it may be secured to the shoulder portion 701 or the sidewall portion 702.

[0089] <3-2. Movement of Tire Assembly>

[0090] The following describes the operation of the tire assembly 7. When the tire assembly 7 is stationary, the average surface separation and actual contact area between the first surface 100 of the first insulating film 110 and the second surface 200 of the second insulating film 210 remain unchanged or barely change. Consequently, no or almost no charge is induced in the first electrode 120 and the second electrode 220, and the power output by the generator 1 is zero or negligible.

[0091] When the tire assembly 7 rotates on the road, the tread portion 700 is impacted in contact with the road surface. This impact is transmitted to the entire tire 70, where it absorbs the impact, causing the sidewall portion 702 to flex, deforming the entire tire 70. The sidewall portion 702 then attempts to recover from the deformation, but is again impacted by the road surface through other parts of the tread portion 700. In this way, the tire 70 as a whole repeatedly undergoes expansion and contraction deformation. The expansion and contraction deformation of the tire 70 is transmitted to the generator 1 fixed to the inner surface of the tread portion 700. The generator 1 deforms in response to the transmitted expansion and contraction deformation of the tire 70. As a result, the first insulating film 110 and the second insulating film 210 move closer to or farther from each other, or their relative positions shift in the planar direction, changing the actual contact area. This induces charges in the first electrode 120 and the second electrode 220, causing the generator 1 to output a greater amount of power than when the tire assembly 7 is stationary.

[0092] The current drawn from generator 1 is proportional to the temporal change in the average inter-surface spacing between first surface 100 and second surface 200. When generator 1 passes over the road surface across tread portion 700 (when the lowest portion of generator 1 is closest to the road surface), the temporal change in the average inter-surface spacing is greatest, resulting in a pair of positive and negative peaks appearing in the voltage waveform output by generator 1. Therefore, the time from the appearance of a peak to the appearance of the next peak represents the time it takes for the tire assembly 7 to complete one rotation. Therefore, the voltage data output by generator 1 can be used to obtain information related to the rotational speed of the tire assembly 7.

[0093] Furthermore, when conditions such as the rotational speed of the tire assembly 7 and the road surface on which the tire assembly 7 rotates are the same, the temporal variation in the average surface separation differs between when the tire 70 is normal (no wear) and when it is worn (slip marks are present). By obtaining the voltage waveform output by the generator 1 at a predetermined rotational speed for both normal and worn tires, and comparing it with the voltage waveform output by the generator 1 at the same rotational speed, it is possible to determine whether the tire 70 is worn. Therefore, it can be said that information regarding the wear of the tire 70 constituting the tire assembly 7 can be obtained from the voltage waveform output by the generator 1.

[0094] Furthermore, under the same conditions as the rotational speed of the tire assembly 7 and the degree of wear of the tire 70, the temporal variation in the average inter-surface distance varies depending on the road surface condition (asphalt, gravel, wet, etc.). For different road surface conditions, by pre-obtaining the voltage waveform output by the generator 1 at a predetermined rotational speed and comparing it with the voltage waveform output by the generator 1 at that rotational speed, the condition of the road surface on which the tire assembly 7 is currently rotating (the road surface on which the vehicle 6 is traveling) can be determined. Therefore, it can be said that information related to the condition of the road surface on which the vehicle 6 is traveling can be obtained from the voltage waveform output by the generator 1.

[0095] The microcomputer 81 stores the power output from the power generator 1 in the storage battery 80. The microcomputer 81 monitors the remaining battery levels of the microcomputer 81 itself, the detection device 82, and the communication device 83 at a predetermined cycle. When the remaining battery level of any battery falls below a predetermined threshold, the power stored in the storage battery 80 is supplied to that battery.

[0096] In parallel with power distribution, the microcomputer 81 stores the detected output values of the power generator 1 and the values output from the detection device 82 in a time-series format in a storage device. The microcomputer 81 transmits this output data stored in the storage device to the control device 60 via the communication device 83 at a predetermined timing. The output data transmission interval can be, for example, once every 40 seconds.

[0097] <4-1. Monitoring system configuration>

[0098] The following describes an example configuration of a system 9 (hereinafter sometimes referred to simply as "system") for monitoring information related to the tire 70, including a tire assembly 7 and a control device 60 of a vehicle 6. For example, the system 9 can begin the following monitoring process when the power of the control device 60 is turned on, and terminate the monitoring process after a predetermined period of time has elapsed while the vehicle 6 is stationary.

[0099] Figure 6 is a diagram showing the entire system 9, Figure 7 This is a block diagram illustrating the electrical configuration of system 9. In system 9, control device 60 receives output data transmitted from module 8 and monitors information related to tire 70. For example, control device 60 monitors the air pressure and rotational speed of tire 70. The air pressure and rotational speed of tire 70 are used, for example, in tire pressure monitoring system (TPMS) processing and load estimation for vehicle 6. Control device 60 also monitors, for example, the wear status of tire 70 and the condition of the road surface on which vehicle 6 is traveling.

[0100] The control device 60 includes a CPU 600, an I / O interface 601, a RAM 602, a ROM 603, and a non-volatile, rewritable storage device 604. The I / O interface 601 is a communication device for communicating with external devices such as the display 65 and the tire assembly 7 via wired or wireless means. The ROM 603 stores a program 610 for controlling the operation of the system 9. The program 610 is written to the ROM 603 from a storage medium 611, such as a CD-ROM or USB memory. The CPU 600 reads and executes the program 610 from the ROM 603, thereby virtually operating as a data acquisition unit 620, an analysis unit 621, and an alarm output unit 622. The operation of each unit will be described in detail later. It should be noted that the program 610 may be stored in the storage device 604 instead of the ROM 603. The RAM 602 and the storage device 604 are used as appropriate for calculations by the CPU 600.

[0101] The storage device 604 is comprised of a hard disk, flash memory, or the like. A tire pressure threshold value used by the analysis unit 621 to determine whether the tire pressure of the tire 70 has decreased is pre-stored in the storage device 604. The tire pressure threshold value may be an air pressure value below which the tire pressure is determined to have decreased. Alternatively, the tire pressure threshold value may be an air pressure obtained by reducing the initial air pressure value of each tire, pre-stored in the storage device 604, according to a preset tire pressure reduction rate.

[0102] Furthermore, the storage device 604 stores, in advance, output waveforms of the generator 1 under various driving conditions of the vehicle 6, for example, as voltage waveforms. The stored voltage waveforms may include, for example, waveforms when the tire 70 is operating normally and waveforms when the tire 70 is worn, at a predetermined rotational speed of the tire assembly 7. Furthermore, the stored voltage waveforms may include waveforms when the vehicle 6 is operating on different types of road surfaces at a predetermined rotational speed of the tire assembly 7. Furthermore, waveforms when the tire 70 is operating normally and waveforms when the tire 70 is worn may be stored for each type of road surface.

[0103] The display 65 is not limited in form as long as it can display various information and convey it to the user. For example, it can be implemented using any form, such as a liquid crystal monitor, a liquid crystal display element, an organic EL display, or a plasma display. The installation location of the display 65 can be selected appropriately, preferably being located in a location easily visible to the driver, such as on the instrument panel. If the control device 60 is connected to a car navigation system, a car navigation monitor or a multi-information display can also be used as the display 65.

[0104] <4-2. Monitoring System Operation>

[0105] Next, a description will be given of a process in which the detection device 82 of the module 8 detects a value related to the air pressure of the tire 70 .

[0106] The data acquisition unit 620 acquires data transmitted from the microcomputer 81. This data includes data related to the air pressure of the tire 70 detected by the detection device 82, data on the output voltage of the generator 1 detected by the microcomputer 81, and data identifying the microcomputer 81 (i.e., the tire assembly 7) as the source of this data. The positions of the wheels to which the tire assemblies 7a to 7d are mounted are pre-associated.

[0107] The analysis unit 621 calculates the current air pressure for each tire assembly 7 based on data related to the air pressure of the tires 70. The analysis unit 621 compares the calculated air pressure with the tire pressure threshold stored in the storage device 604 to determine whether any tire 70 has reduced pressure (abnormal or normal). Furthermore, the analysis unit 621 can use data identifying the tire assembly 7 to identify which tire 70 has reduced pressure. If the analysis unit 621 determines that the pressure is normal, meaning that the pressure of any tire 70 has not decreased, the same process is repeated for the next received data. On the other hand, if the analysis unit 621 determines that the pressure is abnormal, a low tire pressure alarm is output to the alarm output unit 622. The alarm output unit 622 notifies the user of the low tire pressure in the tire 70 by, for example, displaying a warning message on the display 65, prompting the user to adjust the air pressure.

[0108] In parallel or in conjunction with this, the analysis unit 621 calculates the rotational speed of the tire assembly 7 based on the output voltage data of the generator 1. This allows the generator 1 to function as a speed sensor. Furthermore, the calculated rotational speed can be used in an indirect TPMS. Furthermore, the analysis unit 621 compares the output voltage data of the generator 1 with the voltage waveform stored in the storage device 604 to determine whether a worn tire 70 exists (worn or normal). The analysis unit 621 can use the data identifying the tire assembly 7 to identify which tire 70 is worn. If the analysis unit 621 determines that the tire is normal, meaning that no tire 70 is worn, the same process is repeated for the next received data. On the other hand, if the analysis unit 621 determines that the tire is worn, an alarm is output to the alarm output unit 622. The alarm output unit 622 notifies the user of the wear of the tire 70 by, for example, displaying a wear warning message on the display 65, prompting the user to replace the tire.

[0109] The analyzing unit 621 compares the output voltage data of the generator 1 with the voltage waveform stored in the storage device 604 in parallel or before and after this to determine the state of the road surface on which the vehicle 6 is currently traveling. The determination of the road surface state can be performed, for example, at a predetermined time period.

[0110] <5. Modifications>

[0111] While one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications may be made without departing from the gist thereof. For example, the following modifications may be made. In addition, the key points of the following modifications may be appropriately combined.

[0112] <5-1>

[0113] In the above embodiment, information related to the tire 70 is monitored based on time-series data of the voltage output by the generator 1. However, the tire 70 may be monitored based on time-series data of other physical quantities, such as the current flowing through the electrical circuit to which the generator 1 is connected or the power supplied by the generator 1.

[0114] <5-2>

[0115] In the above embodiment, both the first surface 100 and the second surface 200 have the concavo-convex shape. However, the power generator 1 may be configured so that only one of the first surface 100 and the second surface 200 has the concavo-convex shape.

[0116] <5-3>

[0117] The first electrode 120 can be formed by weaving conductive fibers into a fabric. For example, the fibers can be flexible Cu wire or stainless steel wire. Furthermore, the outer periphery of the fibers can be coated with a first insulating film 110, thereby forming the first surface 100. Similarly, the second electrode 220 can be formed by weaving conductive fibers into a fabric, and the outer periphery of the fibers can be coated with a second insulating film 210, thereby forming the second surface 200. For example, the fibers can be flexible Cu wire or stainless steel wire.

[0118] <5-4>

[0119] The power generator 1 of the above embodiment includes the cushioning material 30 and the weight 40. However, it may also be Figure 8A As shown, at least one of the buffer material 30 and the weight 40 is omitted to form the power generator 1. Alternatively, Figure 8B The weight 40 is omitted as shown in the example of the power generation body 1, or Figure 8C As shown in the example of FIG, the buffer material 30 is omitted and the power generation body 1 is constructed. Figure 8B In the example of omitting the weight 40, the cushioning material 30 has a certain degree of mass and can function as a cushioning material, and can also have the function of the weight 40. When the cushioning material 30 also has the function of the weight 40, the cushioning material 30 can be configured so that the density increases as it approaches the first member 10. It should be noted that the cushioning material 30 can be configured by appropriately stacking two or more cushioning materials composed of the same material or two or more cushioning materials composed of different materials.

[0120] <5-5>

[0121] The power generator 1 may include two or more first insulating films 110 , two second insulating films 210 , a first electrode 120 , and a first substrate 130 .

[0122] <5-6>

[0123] In the above embodiment, the external control device 60 of the module 8 is an in-vehicle device, but it may be a portable device such as a smartphone, tablet, or notebook PC installed with the program 610. In this case, the display of the above device may be used as the display 65.

[0124] <5-7>

[0125] Detection device 82 is a device for detecting the air pressure inside tire 70, and the detection method is not limited. For example, a strain gauge, diaphragm, or semiconductor sensor can be used. Furthermore, detection device 82 can be, for example, a temperature sensor for detecting the temperature inside tire 70, or a vibration sensor (acceleration sensor) for detecting the vibration of tire 70.

[0126] <5-8>

[0127] In the system 9 of the above-described embodiment, the analyzing unit 621 calculates the air pressure and rotational speed of the tire 70 and performs processing such as comparing the output waveform of the generator 1. However, the system 9 may be configured so that these processes are performed by the microcomputer 81. In this case, the tire pressure threshold value and the output waveform of the generator 1, which are pre-stored in the storage device 604, may be stored in the storage device of the microcomputer 81.

[0128] <5-9>

[0129] The shape of the package 50 is not limited to that of the above embodiment, and may be modified appropriately, for example, by omitting the flange portion 54. In addition, when the generator 1 is assembled to the tire 70, at least a portion of the package 50 may be formed by the tire 70. For example, Figure 9 As shown, the bottom surface portion 52 of the package 50 may be formed by the inner side surface of the tire 70. That is, the power generator 1 may be sealed by being surrounded by the inner side surface of the tire 70, the side surface portions 53, and the top surface portion 51.

[0130] <5-10>

[0131] The power generator 1 of the above embodiment is assembled inside the tire 70 to constitute the tire assembly 7 , but the application of the power generator 1 is not limited thereto.

[0132] Example

[0133] The following describes experiments conducted by the inventors and their results, but the present invention is not limited thereto.

[0134] <Experimental Conditions>

[0135] An assembly is prepared in which the power generator of the embodiment constructed as described above is arranged on the inner side of the tread portion of the tire and assembled to the tire. Figure 10AA tire rotation test apparatus is shown. Using this test apparatus, a predetermined wheel load is applied to the assembly, and a rotating belt is used to impart a constant speed of rotation. The first and second electrodes of the generator are electrically connected to a data logger external to the assembly. The data logger measures the voltage output by the generator while the assembly rotates at a constant speed.

[0136] The tire size is 215 / 40R17 (approximately 604 mm in diameter), the internal pressure is 200 kPa, the wheel load is 3 kN, and the rotational speed is converted to 40 km / h.

[0137] The generator of the embodiment comprises a first component, a second component, a cushioning material, a weight, and a packaging body. The generator is assembled inside the tire with the first component positioned radially inward and the second component positioned radially outward. Both the first component 10A and the second component 20A are formed into a square shape, each 50 mm on a side, when viewed from above.

[0138] The weight is a uniform plate made of stainless steel (SUS) with a thickness of 0.1mm. The cushioning material is soft polyurethane foam with a thickness of 10mm. The weight and cushioning material are the same size as the first and second parts, and are both formed into a square shape with a side of 50mm when viewed from above. The packaging body is made of butyl rubber and is Figure 4 The shape is the same as shown. L1 is 52 (mm) and L2 is 1 (mm).

[0139] <Experimental Results>

[0140] The output voltage (V) of the generator versus the rotation time (Sec) is shown in the following figure: Figure 10B The experimental results confirmed that the power generator of the example performed good power generation even under conditions assuming actual vehicle travel.

[0141] Explanation of symbols

[0142] 1. Generator

[0143] 6 vehicles

[0144] 7 Tire assembly

[0145] 10 Part 1

[0146] 20 Part 2

[0147] 30 cushioning material

[0148] 40 Heavy Objects

[0149] 41 Pressing surface

[0150] 50 packaging

[0151] 60 Control Device

[0152] 70 tires

[0153] 100 Page 1

[0154] 110 1st insulating film

[0155] 120 1st electrode

[0156] 130 1st base material

[0157] 200 Page 2

[0158] 210 Second insulating film

[0159] 220 Second electrode

[0160] 230 Second base material

Claims

1. A power generator comprising: a first member having a first insulating film forming a first surface; a second member having a second insulating film forming a second surface facing the first surface and in contact with the first surface; and a packaging body that seals the first component and the second component; a cushioning material disposed on a side of the first member opposite to the first surface; a plate-shaped weight disposed between the cushioning material and the first component and forming a pressing surface for pressing the first component; The first member and the second member are configured so that an actual contact area between the first surface and the second surface changes in accordance with pressure applied to the first member and the second member. The first insulating film and the second insulating film are configured so that one is positively charged and the other is negatively charged as the actual contact area changes. The cushioning material is sealed by the packaging body, The heavy object is sealed by the packaging body, The weight is formed so that the pressing surface overlaps entirely with the first surface and the second surface.

2. The power generator according to claim 1, wherein The packaging body is made of rubber or elastomer.

3. The power generator according to claim 1 or 2, wherein: The packaging body is made of butyl rubber.

4. The power generator according to claim 1 or 2, wherein: The weight is made of hard material.

5. The power generator according to claim 1 or 2, wherein: The first member further includes a first electrode on the back side of the first surface, the first electrode being arranged so as to be in contact with the first insulating film. The second member further includes a second electrode on the back side of the second surface, the second electrode being arranged so as to be in contact with the second insulating film. The first electrode and the second electrode are made of a flexible material.

6. A tire assembly comprising: The power generating body according to any one of claims 1 to 5; tires mounted on wheels; and an electronic device that receives power output from the power generator, The power generator is arranged inside the tire.

7. The tire assembly according to claim 6, wherein: The tire assembly further includes a battery for storing the electric power outputted from the power generator. The electronic device receives supply of electric power stored in the battery.

8. The tire assembly according to claim 6 or 7, wherein: The electronic device includes a communication device capable of performing data communication with an external device.

9. A tire monitoring system comprising: The tire assembly according to claim 8; and an external control device capable of performing data communication with the communication device, The communication device transmits at least one output data of the voltage and current output by the power generator and a physical quantity based on at least one of the voltage and current to the external control device, The external control device monitors information related to the tire based on the output data received from the communication device.

10. The tire monitoring system according to claim 9, wherein: The information related to the tire includes at least one of information related to a rotational speed of the tire, information related to wear of the tire, and information related to a state of a road surface on which a vehicle equipped with the tire travels.

11. The tire monitoring system according to claim 9 or 10, wherein: The external control device is mounted on a vehicle including the tire assembly.

12. A tire monitoring method, comprising: A vehicle to be equipped with the tire assembly according to any one of claims 6 to 8; collecting at least one output data of a voltage and a current output by the power generator and a physical quantity based on at least one of the voltage and the current during travel of the vehicle; and Information related to the tire is monitored based on the collected output data.

Images