TWI913386B - Generator - Google Patents

Abstract

[Problem] To provide a generator that can suppress large-scale production while increasing power generation. [Solution] The generator (1) of this invention comprises: a first component (10) having a first surface (11a) covered by a first charged thin film (12), and a second component (20) having a second surface (21a) covered by a second charged thin film (22). The generator (1) generates electricity by changing the contact state between the first surface (11a) and the second surface (21a). The first surface (11a) and the second surface (21a) are uniformly covered with an uneven structure (11a1, 21a1). The second charged thin film (22) is made of a component with a porous structure.

Description

Generator

This invention relates to a generator that generates electricity by utilizing triboelectric charging.

A known generator comprises: a first component having a first surface covered by a first charged thin film, and a second component having a second surface covered by a second charged thin film, which generates electricity by changing the contact state between the first and second surfaces (see, for example, Patent 1). [Prior Art Documents] [Patent Documents]

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

(The problem that the invention aims to solve)

If the aforementioned generator is to increase its power output so as to supply power to electrical machines that consume large amounts of electricity, the contact area between the first surface of the first component and the second surface of the second component can be increased. In this case, the aforementioned generator becomes larger, which limits the places where the generator can be installed and may lead to a reduction in versatility.

The purpose of this invention is to provide a generator that can suppress the increase in size while increasing power generation. (Technical means to solve the problem)

The power generation system of the present invention comprises: a first component having a first surface covered by a first charged thin film, and a second component having a second surface covered by a second charged thin film, wherein the power generation is generated by the change of the contact state between the first surface and the second surface, and at least one of the first surface and the second surface is formed with an uneven structure throughout, wherein at least one of the first charged thin film and the second charged thin film is formed by a component having a porous structure.

Furthermore, the generator of the present invention is preferably formed such that if the aforementioned uneven structure is formed only on one of the aforementioned first surface and the aforementioned second surface, the height of the aforementioned uneven structure from bottom to top is 0.3 mm or more; if the aforementioned uneven structure is formed on both of the aforementioned first surface and the aforementioned second surface, the sum of the height of the aforementioned uneven structure formed on the aforementioned first surface from bottom to top and the height of the aforementioned uneven structure formed on the aforementioned second surface from bottom to top is 0.3 mm or more.

Furthermore, the generator of the present invention is preferably made of polyimide with a porous structure, wherein one of the aforementioned first charged film and the aforementioned second charged film is made of polyimide, and the other is made of polyamide.

Furthermore, the generator of this invention preferably has a porous structure in which the average pore diameter is between 200 nm and 400 nm. (Effects of the Invention)

By using a charged thin film with a porous structure, the amount of electricity carried by the charged thin film can be increased, thereby suppressing large-scale production and increasing the power generation.

Figures 1 to 8 illustrate one embodiment of the present invention. Figure 1 is a cross-sectional view of the generator; Figure 2 is a cross-sectional view of the generator in which force is applied from the outside; Figure 3 is a cross-sectional view of the main part of the second charged film; Figure 4 is a graph showing the test results of the generator voltage of a comparative example generator without the uneven structure; Figure 5 is a graph showing the test results of the generator voltage of the embodiment and the comparative example generator with the uneven structure; Figure 6 is a graph showing the relationship between the number of times of generation and the amount of generation; Figure 7 is a graph showing the relationship between the sum of the heights of the uneven structure and the output variation rate; Figure 8 is a graph showing the relationship between the aperture of the second charged film and the generator voltage.

The generator 1 in this embodiment is, for example, installed on the tire of a vehicle, and generates electricity when the vehicle is moving, due to the force acting on the tire.

The generator 1 generates electricity by means of frictional charging and has: a first component 10 and a second component 20 that carry opposite charges by means of changes in their contact state; and a holding component 30 for holding the first component 10 and the second component 20 together.

The first component 10 has: a first electrode portion 11; and a first charged thin film 12 covering the first electrode portion 11 located on the first surface 11a of the second component 20.

The first electrode portion 11 is made of a conductive and elastic component. The first electrode portion 11 is formed by coating the surface of a conductive elastic body, such as silver or copper, or an insulating elastic body, such as nitrile rubber or silicone rubber, with a conductive film. The conductive film is formed, for example, by a conductive nonwoven fabric.

On the first surface 11a of the first electrode portion 11, a continuous wave-shaped concave-convex structure 11a1 is formed throughout the entire surface. The height H1 of the concave-convex structure 11a1 from the bottom to the top is formed to a predetermined size.

The first charged film 12 is made of a soft component that is insulating and has a charge polarity opposite to that of the second charged film described later. The first charged film 12 is selected from, for example, polymethyl methacrylate, nylon, polyvinyl alcohol, polyester, polyisobutylene, polyurethane, polyethylene terephthalate, polyvinyl butyral, polychloroprene, natural rubber, polyacrylonitrile, polydicarbonate, polystyrene, polyethylene, polypropylene, etc. The first charged film 12 is formed to a thickness of T1 and covers the first surface 11a in a manner that follows the uneven structure 11a1.

The second component 20 has: a second electrode portion 21; and a second charged thin film 22 covering the second surface 21a located on the side of the first component 10.

The second electrode portion 21 is made of a conductive and elastic component. The second electrode portion 21 is formed by coating the surface of a conductive elastic body, such as silver or copper, or an insulating elastic body, such as nitrile rubber or silicone rubber, with a conductive film. The conductive film is formed, for example, from a conductive nonwoven fabric.

On the second surface 21a of the second electrode portion 21, a continuous wave-shaped concave-convex structure 21a1 is formed throughout the entire surface. The height H2 of the concave-convex structure 21a1 from the bottom to the top is formed to a predetermined size.

The second charged thin film 22 is formed of a soft material having insulating properties and a charge polarity opposite to that of the first charged thin film 12. The second charged thin film 22 is formed, for example, of polyimide. The second charged thin film 22 is formed to a thickness of T2 and covers the second surface 21a along the uneven structure 21a1. Furthermore, as shown in FIG. 3, the second charged thin film 22 has a porous structure with numerous pores 22a and connecting holes 22b that connect adjacent pores 22a to each other. The average pore diameter D of the pores 22a of the second charged thin film 22 is preferably in the range of 200 nm to 400 nm, and the average pore diameter d of the connecting holes 22b is preferably less than one-third of the average pore diameter D. Furthermore, the second charged thin film 22 preferably has a porosity of 50% or more. From the perspective of increasing the specific surface area to improve chargeability, it is preferable to have openings on the surface. There is no particular upper limit to the porosity, for example, 85% or less. In terms of film strength, 80% or less is preferred.

The second charged thin film 22 is formed with pores 22a by, for example, a composite film comprising: a resin as a substrate or a precursor resin of a resin as a substrate, and microparticles, and therefore can be manufactured by removing the microparticles. Examples of substrate resins or precursor resins include: polyimide resins or precursor resins of polyimide resins. The porous membrane constituting the second charged thin film 22 can be manufactured by known methods, such as those described in Japanese Patent No. 5745195 or Japanese Patent No. 6147069. If the second charged thin film 22 is a polyimide porous film, it may also include a portion of the polyimide amide bond as an open-ring amide bond. However, in terms of the processability of the generator of the present invention, it is preferable to use polyimide that does not contain amide bonds, which can be confirmed by an FT-IR device.

Here, the sum of the height H1 of the concave-convex structure 11a1 on the first surface 11a and the height H2 of the concave-convex structure 21a1 on the second surface 21a is preferably 0.3 mm or more, and more preferably 0.6 mm or more. The sum of the height H1 of the concave-convex structure 11a1 and the height H2 of the concave-convex structure 21a1 also includes cases where only one of the first surface 11a and the second surface 21a has a concave-convex structure, while the other is planar. For example, if the first surface 11a has a concave-convex structure 11a1 and the second surface 21a is planar, the height H1 of the concave-convex structure 11a1 is preferably 0.3 mm or more, and more preferably 0.6 mm or more. Furthermore, if the first surface 11a is planar and the second surface 21a has a concave-convex structure 21a1, the height H2 of the concave-convex structure 21a1 is preferably 0.3 mm or more, and preferably 0.6 mm or more.

The thickness T1 of the first charged thin film 12 or the thickness T2 of the second charged thin film 22 is preferably 80 μm or less. In addition, the thickness T1 of the first charged thin film 12 and the thickness T2 of the second charged thin film 22 are preferably 80 μm or less.

Furthermore, the first electrode portion 11 and the second electrode portion 21 are electrically connected to each other through an external load supplied with generated power. If a potential difference is generated between the first electrode portion 11 and the second electrode portion 21, electrons will flow between the first electrode portion 11 and the second electrode portion 21.

The retaining component 30 is as shown in Figure 1, which is a component that integrally retains the first component 10 and the second component 20 with the first surface 11a of the first component 10 and the second surface 21a of the second component 20 facing each other.

The generator 1 configured as shown above generates electricity by switching between a first state in which the force does not act from the outside in the direction that pushes the first charged film 12 and the second charged film 22 against each other, and a second state in which the force acts from the outside in the direction that pushes the first charged film 12 and the second charged film 22 against each other.

In the first state, the first charged film 12 and the second charged film 22 are in contact with each other. However, the first charged film 12 formed along the concave-convex structure 11a1 and the second charged film 22 formed along the concave-convex structure 21a1 are facing each other, so the contact area of the first charged film 12 and the second charged film 22 is small.

On the other hand, in the second state, a force is applied in the direction that pushes the first charged film 12 and the second charged film 22 against each other. As shown in FIG. 2, the irregular structure 11a1 of the elastic first electrode portion 11 and the irregular structure 21a1 of the second electrode portion 21 are deformed respectively, and the contact area of the first charged film 12 and the second charged film 22 becomes larger than the contact area in the first state. At this time, due to the friction between the first charged film 12 and the second charged film 22, the first component 10 carries a positive charge, and the second component 20 carries a negative charge.

Furthermore, if the force acting on the first surface 11a and the second surface 21a that is pressing against each other is released from the second state, the first state is formed by the elastic forces of the first electrode portion 11 and the second electrode portion 21. At this time, electricity flows between the first electrode portion 11 and the second electrode portion 21 in a direction where the potentials become equal. [Example]

The invention will be explained in detail below through examples.

As shown in Table 1, tests were conducted on the generators of Comparative Examples 1-7 and Embodiments 1-5, which were constructed by changing the material of the first charged thin film 12 of the first component 10 and the height H1 of the uneven structure 11a1, and the material of the second charged thin film 22 of the second component 20 and the height H2 of the uneven structure 21a1, to evaluate the performance of each generator.

<Comparative Example 1> Comparative Example 1 is characterized by the absence of an uneven structure 11a1 on the first surface 11a of the first component 10, the first charged film 12 being a non-porous polyurethane, the absence of an uneven structure 21a1 on the second surface 21a of the second component 20, and the second charged film 22 being a non-porous polyimide.

<Comparative Example 2> Comparative Example 2 features a first surface 11a of the first component 10 with a height H1 of 0.2 mm for the uneven structure 11a1. The first charged film 12 is made of polyurethane without a porous structure. The uneven structure 21a1 of the second surface 21a of the second component 20 is not formed. The second charged film 22 is made of polyimide without a porous structure.

<Comparative Example 3> Comparative Example 3 is characterized by the absence of an uneven structure 11a1 on the first surface 11a of the first component 10, the first charged film 12 being a non-porous polyurethane, the absence of an uneven structure 21a1 on the second surface 21a of the second component 20, and the non-porous tetrafluoroethylene/hexafluoropropylene copolymer of the second charged film 22.

<Comparative Example 4> Comparative Example 4 involves a first component 10 with a first surface 11a, the height H1 of the uneven structure 11a1 being 0.5 mm, and a first charged film 12 being a non-porous polyurethane. The second component 20 has a second surface 21aa with an uneven structure 21a1 having a height H2 of 0.2 mm, and a second charged film 22 being a non-porous tetrafluoroethylene/hexafluoropropylene copolymer.

<Comparative Example 5> Comparative Example 5 involves a first component 10 with a first surface 11a, the height H1 of the uneven structure 11a1 being 0.5 mm, and a first charged film 12 being a non-porous polyurethane. The second component 20 has a second surface 21aa with an uneven structure 21a1 having a height H2 of 0.5 mm, and a second charged film 22 being a non-porous tetrafluoroethylene/hexafluoropropylene copolymer.

<Comparative Example 6> Comparative Example 6 is characterized by the absence of an uneven structure 11a1 on the first surface 11a of the first component 10, the first charged film 12 being a non-porous polyurethane, the absence of an uneven structure 21a1 on the second surface 21a of the second component 20, and the presence of a porous polyimide second charged film 22.

<Example 1> In Example 1, on the first surface 11a of the first component 10, the height H1 of the uneven structure 11a1 is 0.5 mm, the first charged film 12 is a non-porous polyurethane, and on the second surface 21a of the second component 20, the height H2 of the uneven structure 21a1 is 0.2 mm, and the second charged film 22 is a porous polyimide.

<Example 2> In Example 2, on the first surface 11a of the first component 10, the height H1 of the uneven structure 11a1 is 0.5 mm, the first charged film 12 is a non-porous polyurethane, and on the second surface 21a of the second component 20, the height H2 of the uneven structure 21a1 is 0.5 mm, and the second charged film 22 is a porous polyimide.

<Example 3> In Example 3, on the first surface 11a of the first component 10, the height H1 of the uneven structure 11a1 is 0.2 mm, the first charged film 12 is polyimide without a porous structure, and on the second surface 21a of the second component 20, the height H2 of the uneven structure 21a1 is 0.2 mm, and the second charged film 22 is polyimide with a porous structure.

<Example 4> In Example 4, on the first surface 11a of the first component 10, the height H1 of the uneven structure 11a1 is 0.2 mm, the first charged film 12 is polyimide without a porous structure, and on the second surface 21a of the second component 20, the height H2 of the uneven structure 21a1 is 0.5 mm, and the second charged film 22 is polyimide with a porous structure.

<Example 5> In Example 5, on the first surface 11a of the first component 10, the height H1 of the uneven structure 11a1 is 0.5 mm, the first charged film 12 is polyimide without a porous structure, and on the second surface 21a of the second component 20, the height H2 of the uneven structure 21a1 is 0.5 mm, and the second charged film 22 is polyimide with a porous structure.

Figure 4 is a graph showing the results of the test on the generation voltage for the generator 1 of Comparative Examples 1, 3, and 6. In Comparative Examples 1, 3, and 6, no uneven structure 11a1 is formed on the first surface 11a of the first electrode portion 11, nor is an uneven structure 21a1 formed on the second surface 21a of the second electrode portion 21. Therefore, in Comparative Examples 1, 3, and 6, the generation voltage is less than 20 volts in any one of them.

Figure 5 is a graph showing the results of tests on the generation voltage for Comparative Examples 2, 4 and 5, and Examples 1, 2, 3 and 4. Comparative Examples 2, 4 and 5, and Examples 1, 2, 3 and 4 have an uneven structure formed on at least one of the first surface 11a and the second surface 21a. Therefore, in Comparative Examples 2, 4 and 5, and Examples 1, 2, 3 and 4, it is shown that even the lower generation voltage is above 50 volts. Furthermore, since the second charged film 22 is a polyimide with a porous structure, namely Examples 1, 2, 3 and 4, the amount of electricity carried by the second charged film 22 increases due to its larger surface area, resulting in a higher generation voltage of at least 200 volts. This is higher than that of the second charged film 22 being a material without a porous structure, namely Comparative Examples 2, 4 and 5.

Figure 6 is a graph showing the results of an experiment measuring the relationship between the number of times of power generation and the amount of power generated by repeatedly switching between the first and second states, for Comparative Examples 5, 3, 4, and 5. Compared with Comparative Example 5, where the second charged film 22 does not have a porous structure, it can be seen that even with an increased number of power generation times, the rate of decrease in the amount of power generated in Examples 3, 4, and 5 is small. Furthermore, it can be seen that in Examples 3, 4, and 5, as the sum of the height H1 of the uneven structure 11a1 and the height H2 of the uneven structure 21a1 increases, the contact area between the first charged film 12 and the second charged film 22 remains large in both the first and second states, and the relative rate of decrease in the amount of power generated is low.

Figure 7 is a graph showing, for embodiments 3, 4, and 5, the relationship between the sum of the height H1 of the concave-convex structure 11a1 and the height H2 of the concave-convex structure 21a1, and the output variation rate, which represents the maximum reduction ratio of power generation when the power generation becomes relatively minimum during repeated switching between the first and second states. Figure 7 shows that as the sum of the height H1 of the concave-convex structure 11a1 and the height H2 of the concave-convex structure 21a1 increases, the output variation rate decreases.

Figure 8 shows the power generation voltages in Embodiment 2 when the average pore size D of the porous structure pores 22a is formed to be 100 nm, 300 nm, and 2500 nm. When the average pore size D is formed to be 100 nm, the power generation voltage is approximately 170 volts; when the average pore size D is formed to be 300 nm, the power generation voltage is approximately 370 volts; and when the average pore size D is formed to be 2500 nm, the power generation voltage is approximately 80 volts. As shown above, when the average pore size D of the porous structure 22a is formed to be 300 nm, the power generation voltage is higher compared to when the average pore size D is formed to be 100 nm or 2500 nm.

As shown above, the generator 1 according to this embodiment is a generator having: a first component 10 having a first surface 11a covered by a first charged thin film 12 and a second component 20 having a second surface 21a covered by a second charged thin film 22, and generating electricity by changing the contact state between the first surface 11a and the second surface 21a. The first surface 11a and the second surface 21a have a concave-convex structure 11a1 and 21a1 formed all over the first surface 11a and the second surface 21a. The second charged thin film 22 is made of a component with a porous structure.

In this way, by using a porous component as the second charged film 22, the amount of electricity carried by the second charged film can be increased, thereby suppressing large-scale production and increasing the power generation.

Furthermore, it is preferable that if the concave-convex structure 11a1 and 21a1 are formed only on one of the first surface 11a and the second surface 21a, the distance between the top and bottom of the concave-convex structure 11a1 and 21a1 is 0.3 mm or more; if the concave-convex structure 11a1 and 21a1 are formed on both the first surface 11a and the second surface 21a, the sum of the distance H1 between the top and bottom of the concave-convex structure 11a1 formed on the first surface 11a and the distance H2 between the top and bottom of the concave-convex structure 21a1 formed on the second surface 21a is 0.3 mm or more.

Therefore, in the case of repeated power generation, the rate of decrease in relative power generation is reduced, and the output fluctuation rate is reduced, thereby improving durability and output stability.

Furthermore, the aforementioned first charged film 12 is made of polyamide, and the second charged film 22 is made of porous polyamide.

This allows for an increase in generation voltage and a further increase in power generation.

Furthermore, the average aperture D of the pores in the second charged thin film 22 is between 200 nm and 400 nm.

This allows for an increase in the generation voltage compared to other average apertures D, thus increasing the power generation.

In the aforementioned embodiments, the first charged film 12 is formed from a component without a porous structure, and the second charged film 22 is formed from a component with a porous structure; however, this is not a limitation. For example, the first charged film 12 may be formed from a component with a porous structure, and the second charged film 22 may be formed from a component without a porous structure, or both the first and second charged films may be formed from a component with a porous structure, provided that at least one of the first and second charged films is formed from a component with a porous structure.

Furthermore, while polyimide is shown as a component with a porous structure in the aforementioned embodiments, it is not limited to this. Components that can form a porous structure may also be components other than polyimide.

Furthermore, the aforementioned embodiments show a generator 1 that generates electricity by applying force from the outside to the first charged film 12 and the second charged film 22 in a direction that pushes them against each other; however, this is not a limitation. The present invention can also be applied to a generator that generates electricity by applying force from the outside to the direction in which the first and second components move along the first and second surfaces while the first and second charged films are in contact.

1: Generator 10: First Component 11: First Electrode 11a: First Surface 11a1: Uneven Structure 12: First Charged Thin Film 20: Second Component 21: Second Electrode 21a: Second Surface 21a1: Uneven Structure 22: Second Charged Thin Film 22a: Hole 22b: Through Hole 30: Holding Component D,d: Average Hole Diameter H1,H2: Height T1,T2: Thickness Dimension

[Figure 1] is a cross-sectional view of a generator according to one embodiment of the present invention. [Figure 2] is a cross-sectional view showing the generator according to one embodiment of the present invention with the first and second components subjected to external force. [Figure 3] is a cross-sectional view of the main portion of the second charged film according to one embodiment of the present invention. [Figure 4] is a graph showing the results of a test on the generation voltage of a generator that does not have the uneven structure of one embodiment of the present invention. [Figure 5] is a graph showing the results of a test on the generation voltage of a generator that has the uneven structure of one embodiment of the present invention and a comparative example. [Figure 6] is a graph showing the relationship between the number of times of generation and the amount of power generated according to one embodiment of the present invention. [Figure 7] is a graph showing the relationship between the sum of the heights of the uneven structure in one embodiment of the present invention and the output variation rate. [Figure 8] is a graph showing the relationship between the aperture diameter of the second charged thin film in one embodiment of the present invention and the generation voltage.

1: Generator

10: First Component

11: First Electrode Section

11a: Page 1

11a1: Concave-convex structure

12: The first charged thin film

20: Second component

21: Second electrode section

21a: Page 2

21a1: Concave-convex structure

22: Second charged thin film

30: Retaining Components

H1, H2: Height

T1, T2: Thickness dimensions

Claims (3)

A generator comprises: a first component having a first surface covered by a first charged thin film, and a second component having a second surface covered by a second charged thin film; the generator generates electricity by changing the contact state between the first and second surfaces; at least one of the first and second surfaces is formed with a textured surface; one of the first and second charged thin films is made of polyimide with a porous structure, and the other is made of polyimide. As in claim 1, the generator, if the aforementioned uneven structure is formed only on one of the first and second surfaces, has a height of 0.3 mm or more from bottom to top; if the aforementioned uneven structure is formed on both the first and second surfaces, the sum of the height of the uneven structure formed on the first surface from bottom to top and the height of the uneven structure formed on the second surface from bottom to top is 0.3 mm or more. As in claim 1 or claim 2, the aforementioned component with a porous structure has an average pore diameter of 200 nm to 400 nm.