Power generation element and weight sensor

Abstract

To provide a power generation element that is easy to manufacture and capable of improving power generation performance. [Solution] The present invention relates to a power generation element comprising two electrodes spaced apart from each other, and a charged body placed in contact between the two electrodes, wherein the charged body includes a positively charged layer and a negatively charged layer in surface contact with the positively charged layer, and the positively charged layer includes rubber as a matrix material and a conductive filler with higher conductivity than the rubber.

Description

Technical Field

[0001] The present invention relates to a power generation element.

Background Art

[0002] In recent years, energy harvesting technology has become important. For example, according to vibration power generation, long-term energy supply can be achieved without charging, replacement, or fuel replenishment. Therefore, if the power source can be switched from the existing power source to a power source by vibration power generation, it can contribute not only to the promotion of energy conservation but also to the solution of the problem of waste treatment of used batteries and the like.

[0003] In vibration power generation, many methods such as the piezoelectric method, the electromagnetic induction method, and the magnetostriction method have been studied and commercialized. However, at present, many of these methods have a limited range of applications because their structures are complex and difficult to deform (see Non-Patent Document 1).

[0004] Among these, a power generation element that utilizes charging by friction can generate a potential difference simply by contacting charged bodies made of two different substances, so its structure can be made relatively simple. Therefore, if the power generation performance of the power generation element can be improved, its application range can be further expanded. In order to improve the output of the friction-based power generation element, an invention in which an ionic liquid is included in the charged body has been disclosed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] However, the above invention requires adding a liquid additive to a solid resin and mixing the two. Several mixing methods have been proposed, but none of them are particularly easy to handle.

[0008] Therefore, the present invention aims to provide a power generation element that is easy to manufacture and capable of improving power generation performance. [Means for solving the problem]

[0009] (1) A power generation element according to one embodiment for achieving the above objective is: Two electrodes are spaced apart from each other, The system comprises a charged body positioned in contact between the two electrodes, The charged body is A positively charged layer, A negatively charged layer that is in surface contact with the positively charged layer, Includes, The positively charged layer comprises rubber as a matrix material and a conductive filler with higher conductivity than the rubber. (2) A power generation element according to another embodiment is: At least three electrodes that are spaced apart from each other, The device comprises a charged body placed in contact between the at least three electrodes, The two charged bodies, which are positioned opposite each other with the electrode in between, have the same charged layer (either a positive or negative charge layer) facing the electrode. The positively charged layer comprises rubber as a matrix material and a conductive filler with higher conductivity than the rubber. (3) In a power generation element according to another embodiment, the conductive filler may preferably include carbon nanotubes. (4) In a power generation element according to another embodiment, the conductive filler may preferably contain carbon black. (5) The power generation element according to another embodiment preferably may include a fluororesin in the negatively charged layer. (6) The power generation element according to another embodiment preferably may be polytetrafluoroethylene as the fluororesin. (7) The power generation element according to another embodiment preferably may include silicone rubber in the positively charged layer. [Advantages of the Invention]

[0010] According to the present invention, it is possible to provide a power generation element that is easy to manufacture and can enhance power generation performance. [Brief Description of the Drawings]

[0011] [Figure 1] FIG. 1 shows an exploded perspective view of a power generation element according to the first embodiment. [Figure 2] FIG. 2 shows a longitudinal sectional view of a power generation element according to the first embodiment, and an enlarged view of a part A of the longitudinal sectional view. [Figure 3] FIG. 3 shows a longitudinal sectional view similar to FIG. 2 of a power generation element according to the second embodiment, and enlarged views of parts B and C of the longitudinal sectional view. [Modes for Carrying Out the Invention]

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below do not limit the invention according to each claim of the claims. Also, not all of the elements and combinations thereof described in the embodiments are essential for the solution means of the present invention. [First Embodiment] 1. Configuration of Power Generation Element

[0013] FIG. 1 is an exploded perspective view of a power generation element according to the first embodiment.

[0014] The power generation element 1a has two electrodes 10a and 10b that are spaced apart from each other, a fluororesin layer 21 as a negatively charged layer, and a rubber layer 22 as a positively charged layer. The fluororesin layer 21 and the positively charged layer 22 are in contact with each other. The electrode 10a and the fluororesin layer 21, and the electrode 10b and the positively charged layer 22 are in contact with each other. The material of the negatively charged layer may be any material that is more likely to be negatively charged than rubber in the charging series. The rubber layer 22 includes rubber as a matrix material and a conductive filler that is more conductive than the rubber.

[0015] FIG. 2 shows a longitudinal sectional view of the power generation element according to the first embodiment, and an enlarged view of a part A of the longitudinal sectional view.

[0016] In the power generation element 1a, the electrodes 10a and 10b that are spaced apart from each other sandwich a charged body 20a. The charged body 20a includes a fluororesin layer 21 and a rubber layer 22. The rubber layer 22 includes rubber as a matrix material and a conductive filler that is more conductive than the rubber. The fluororesin layer 21 and the rubber layer 22 are in surface contact with each other. Carbon black forms a chain structure in the rubber layer and becomes a conductive circuit. Through this conductive circuit, the electrode 10b and the fluororesin layer 21 are connected.

[0017] 2. Fluororesin layer (negatively charged layer) The fluororesin used for the fluororesin layer 21 is not particularly limited. Examples thereof include polyvinylidene fluoride (PVDF), a vinylidene fluoride-based copolymer, polytetrafluoroethylene (PTFE), and porous polytetrafluoroethylene (PTFE). Among these, polytetrafluoroethylene (PTFE) is more preferable.

[0018] 3. Rubber layer (positively charged layer) (1) Rubber The rubber used in the rubber layer 22 is not particularly limited. Examples of rubbers include natural rubber (NR), styrene-butadiene rubber (SBR), butyl rubber (IIR), nitrile rubber (NBR), ethylene-propylene rubber (EPM), chloroprene rubber (neoprene) (CR), silicone rubber (Si), fluororubber (Viton) (FKM), isoprene rubber (IR), butadiene rubber (BR), acrylic rubber (ACM ANM), chlorosulfonated polyethylene rubber (Hypalon) (CSM), urethane rubber (PUR), ethylene-vinyl acetate rubber (EVA), epichlorohydrin rubber (CO), and polyfluoropolymer rubber (Thiokol) (T). Among these, silicone rubber is more preferred.

[0019] (2) Conductive filler Examples of conductive fillers used in the rubber layer 22 include carbon-based fillers such as carbon black, carbon nanotubes, carbon nanofibers, graphite carbon, and carbon fibers; metals in powder, fibrous, or foil form; metal oxides; and metal nitrides. Among these, carbon black and carbon nanotubes are preferred from the viewpoint of increasing the electromotive force of the power generation element 1a, with carbon black being particularly preferred.

[0020] 4.Electrode As electrodes 10a and 10b, conductive plates can be used. Here, "conductive" means that the volume resistivity is 10 ―2 This means that the impedance is less than or equal to (Ωm). Examples of conductive plate materials include copper, aluminum, silver, gold, tungsten, or alloys containing one or more of these metals, or graphite. Electrode 10a and the fluororesin layer 21, and electrode 10b and the rubber layer 22 may be bonded together.

[0021] Furthermore, the electrodes may be thin films with a thickness on the order of nanometers or microns formed using film deposition technology, instead of, for example, plate materials with a thickness on the order of millimeters manufactured by molding. Examples of methods for forming the thin films include vapor deposition, PVD methods such as sputtering, or CVD methods that utilize gas reactions. <Second Embodiment>

[0022] Figure 3 shows a longitudinal cross-sectional view of the power generation element according to the second embodiment, in the same view as Figure 2, as well as enlarged views of parts B and C of the longitudinal cross-sectional view.

[0023] In the power generation element 1b according to this embodiment, the fluororesin layer 21, the rubber layer 22, and the electrodes 10a and 10b are the same as in the first embodiment, so a redundant explanation will be omitted here. The power generation element 1b comprises three spaced electrodes 10a, 10b, and 10c, and two charged bodies 20a that are in contact with each other between electrodes 10a and 10c, and between electrodes 10b and 10c. The two charged bodies 20a, which are positioned opposite each other with electrode 10c in between, are both positioned so that the rubber layer 22, which is the positively charged layer, faces electrode 10c. Here, the two charged bodies 20a may be positioned so that the same positively charged layer and negatively charged layer of the same material face electrode 10c. That is, the two charged bodies 20a may both be positioned so that the fluororesin layer 21, which is the negatively charged layer, faces electrode 10c (not shown).

[0024] There are two charged bodies 20a, which is one more than in the case of power generation element 1a. Therefore, the electromotive force of power generation element 1b will be higher than that of power generation element 1a.

[0025] In this way, the electromotive force of the power generation element 1b can be increased by increasing the number of charged bodies 20a, which include the fluororesin layer 21 and the rubber layer 22. Even when the power generation element has many charged bodies, adjacent charged bodies can share electrodes. Therefore, the increase in the thickness of the power generation element that occurs with an increase in the number of charged bodies can be suppressed. As a result, it is possible to efficiently increase the electromotive force of the power generation element. [Examples]

[0026] The present invention will be described in detail below, comparing examples and comparative examples. However, the present invention is not limited to these examples.

[0027] <Material> Details of the materials used in each example and comparative example are as follows.

[0028] [Fluororesin sheet] • Nitoflon No. 900UL: Polytetrafluoroethylene (PTFE) sheet manufactured by Nitto Denko Corporation.

[0029] [Silicone rubber sheet] • SR50: Silicone rubber sheet manufactured by Tigers Polymer Co., Ltd. • S24-CNT-002: Silicone rubber sheet containing carbon nanotubes, manufactured by Zeon Corporation. • KE-3601SB: Carbon black-containing silicone rubber sheet manufactured by Shin-Etsu Chemical Co., Ltd.

[0030] [electrode] • EGGS: Sold by Osato Co., Ltd., Aluminum (Al) sheet

[0031] [Fabrication of power generation elements] <Example 1> Two aluminum plates measuring 10cm x 10cm x 1.0mm in length x width x thickness were prepared and used as electrodes for the power generation element. A charged body was obtained by overlapping a PTFE sheet cut to 10cm x 10cm x 0.1mm in length x width x thickness and a carbon black-containing silicone rubber sheet cut to 10cm x 10cm x 2.0mm in length x width x thickness, ensuring that neither sheet protrudes from the other. The power generation element was fabricated by sandwiching the obtained charged body between the electrodes mentioned above. To ensure adhesion between the materials, the materials were stacked while applying pressure, and air between the materials was removed.

[0032] <Example 2> Two charged materials from Example 1 were placed between three electrodes, and the two charged materials were positioned so that the side of the silicone rubber sheet was in contact with the middle electrode of the three electrodes. The power generation element was fabricated under the same conditions as in Example 1.

[0033] <Example 3> The carbon black-containing silicone rubber sheet was replaced with a carbon nanotube-containing silicone rubber sheet. All other conditions were the same as in Example 1 when fabricating the power generation element.

[0034] <Example 4> The carbon black-containing silicone rubber sheet was replaced with a carbon nanotube-containing silicone rubber sheet. All other conditions were the same as in Example 2 when fabricating the power generation element.

[0035] <Comparative Example 1> The carbon black-containing silicone rubber sheet was replaced with a silicone rubber sheet that does not contain conductive fillers. The power generation element was fabricated under the same conditions as in Example 1.

[0036] <Comparative Example 2> The carbon black-containing silicone rubber sheet was replaced with a silicone rubber sheet that does not contain conductive fillers. The power generation element was fabricated under the same conditions as in Example 2.

[0037] <Evaluation of power generation performance for each example and comparative example> Each measurement described below was performed three times, and the average value was calculated. The measuring equipment consisted of an electrode in contact with silicone rubber as the positive electrode and an electrode in contact with fluororesin as the negative electrode. Power generation performance was evaluated using an oscilloscope (Tektronix, TDS2002) and a multimeter (Sanwa, PC500A). The oscilloscope measurements recorded the maximum values ​​of the generated positive and negative voltages. The multimeter measurements measured voltage in AC mode, and capacitance was also measured.

[0038] Furthermore, the electromotive force of the power generation element was evaluated by visually checking the light emission of the light-emitting diode connected to the power generation element.

[0039] A cylindrical weight (33 mm in diameter, 61 mm in height, and weighing 130 g) was dropped from a height of 4 cm above a horizontally placed power generation element, towards the center of the element's electrodes. The weight was positioned so that its height direction was perpendicular to the in-plane direction of the electrodes, causing it to collide with the power generation element. The voltage generated between the electrodes of the power generation element due to the impact load from the impact of the weight (hereinafter also referred to as "Load 1") was measured. Furthermore, the voltage generated by the impact load (hereinafter also referred to as "Load 2") when a cylindrical weight (33 mm in diameter, 122 mm in height, and weighing 260 g) was dropped from a height of 6 cm above the power generation element was also measured.

[0040] In the illuminance evaluation using light-emitting diodes, the degree of light emission due to the blinking of the light-emitting diodes was evaluated in the following three stages. 1: When it lights up 2: When the light is on brightly 3: When the light is very bright

[0041] Table 1 shows the results of each evaluation test.

[0042] [Table 1]

[0043] Under load 1, the voltage values ​​obtained by measuring Comparative Example 1 using an oscilloscope were +14.3V and -7.2V. The values ​​obtained for Example 1 were significantly higher, at +53.0V and -20.7V. The voltage values ​​obtained by measuring with a tester were also higher for Example 1 (4.7V) compared to 2.5V for Comparative Example 1. The illuminance evaluation result for Example 1 was also significantly higher (3) than for Comparative Example 1 (1).

[0044] On the other hand, under load 1 conditions, the voltage values ​​obtained by measuring with an oscilloscope for Example 3 were +9.5V and -7.5V, and the voltage value obtained by measuring with a tester was 0.3V. Example 3 showed slightly lower voltage values ​​than Comparative Example 1. In Comparative Example 1 and Example 1, the difference between the positive and negative voltage values ​​obtained by measuring with an oscilloscope was large. In Example 3, this voltage difference was small, indicating higher voltage stability. The illuminance evaluation for Example 3 was 1, the same as Comparative Example 1.

[0045] When the load applied to the power generation element is increased from load 1 to load 2, the positive voltage value obtained by measuring with an oscilloscope increases in all cases of Comparative Example 1, Example 1, and Example 3. From this, it was found that a power generation element using silicone rubber containing carbon black and carbon nanotubes can be applied to a weight sensor.

[0046] In each example and comparative example, increasing the number of charged elements from one to two tended to increase the generated voltage. Each example showed a higher voltage value compared to the comparative example. Under load 2, the voltage values ​​obtained by measuring with an oscilloscope for Example 2 were +80.0V and -40.5V, the highest values. Furthermore, under loads 1 and 2, the positive and negative voltage values ​​obtained by measuring for Example 4 were the same, showing the highest voltage stability. The illuminance evaluation for Examples 2 and 4 was high at 3. In each example, an effect of improving the power generation performance of the power generation element was observed. [Industrial applicability]

[0047] The present invention can be used, for example, as a weight sensor or a power generation element. [Explanation of symbols]

[0048] 1a, 1b... Power generation element, 10a, 10b, 10c... Electrode, 20a, 20b... Charged body, 21... Fluororesin layer, 22... Rubber layer (containing conductive filler), 23... Rubber layer (not containing conductive filler).

Claims

1. Two electrodes are spaced apart from each other, The system comprises a charged body placed in contact between the two electrodes, The charged body is A positively charged layer, A negatively charged layer that is in surface contact with the positively charged layer, Includes, The positively charged layer is characterized by comprising rubber as a matrix material and a conductive filler with higher conductivity than the rubber.

2. At least three electrodes with adjacent electrodes spaced apart, The device comprises a charged body placed in contact between the at least three electrodes, The two charged bodies, which are positioned opposite each other with the electrode in between, have the same charged layer (either a positive or negative charge layer) facing the electrode. The positively charged layer is characterized by comprising rubber as a matrix material and a conductive filler with higher conductivity than the rubber.

3. The power generation element according to claim 1 or 2, characterized in that the conductive filler includes carbon nanotubes.

4. The power generation element according to claim 1 or 2, characterized in that the conductive filler contains carbon black.

5. The power generation element according to claim 1 or 2, characterized in that the negatively charged layer contains a fluororesin.

6. The power generation element according to claim 4, characterized in that the fluororesin is polytetrafluoroethylene.

7. The power generation element according to claim 1 or 2, characterized in that the positively charged layer includes silicone rubber.

Images