Ultrafine bubble production device

Abstract

To improve the performance of an ultrafine bubble production device. An ultrafine bubble production device includes: a storage part in which a storage space configured to store a liquid and a gas is formed, the storage part having one end to be closed; a drive part configured to generate energy used for compressing the storage space and pressurizing and dissolving the gas in the liquid; and a plunger part configured to close the one end of the storage part, slide through an interior of the storage part by using the energy to compress the storage space, and after compressing the storage space, decompress the storage space to generate ultrafine bubbles.

Description

Technical Field

[0001] The present disclosure relates to an ultrafine bubble production device.Background Art

[0002] In recent years, the applied technology of fine bubbles has attracted attention. The technology has been put into practical use in cleaning, fishing, and agriculture since around 2004, and its fields have become diverse, including food and medical care. Under such circumstances, the Ministry of Economy, Trade and Industry determined to support and promote international standardization activities related to fine bubbles in 2012 in response to demand from the industry. The Technical Committee on Fine Bubble Technologies was established by the International Organization for Standardization (ISO) in 2013, and has discussed various definitions and standards related to "fine bubbles". As one of the outcomes, a unified classification of bubbles, which were not clearly distinguished by their size in the related art, has been established with the progress of academic research and technology. Specifically, bubbles having a diameter of less than 100 µm are classified as fine bubbles to distinguish them from other bubbles. Furthermore, bubbles having a diameter of less than 1 µm are referred to as ultrafine bubbles (Non-Patent Literature 1 and Non-Patent Literature 2).

[0003] In the related art, a production device has been proposed that is an ultrafine bubble production device including a storage part storing a liquid and a gas, and a drive part used for pressurization of the storage part, in which, in the pressurization, the time required for the pressure to reach the maximum pressure from a start of the pressurization is 2.0 milliseconds or less, and the maximum pressure is 4.00 MPa or more (Patent Document 1).Citation ListPatent Document

[0004] Patent Document 1: WO 2021 / 090833Non-Patent Literature

[0005] Non-Patent Literature 1: Ultrafine bubbles, the Journal of the Acoustical Society of Japan, Vol. 73, No. 7 (2017) Non-Patent Literature 2: What is fine bubble?, [online], the Union of Fine Bubble Scientists and Engineers, [searched on April 10, 2023], Internet <http: / / www.fb-union.org / about.html> Summary of InventionTechnical Problem

[0006] An object of the present disclosure is to provide a technique that improves the performance of an ultrafine bubble production device.Solution to Problem

[0007] An ultrafine bubble production device according to the present disclosure can be implemented by the following aspects. That is, the gist of the technique according to the present disclosure is described below. [1] An ultrafine bubble production device includes: a storage part in which a storage space configured to store a liquid and a gas is formed, the storage part having one end to be closed; a drive part configured to generate energy used for compressing the storage space and pressurizing and dissolving the gas in the liquid; and a plunger part configured to close the one end of the storage part, slide through an interior of the storage part by using the energy to compress the storage space, and after compressing the storage space, decompress the storage space to generate ultrafine bubbles. [2] The ultrafine bubble production device described in [1], in which the plunger part includes a decompression valve that is opened by an inertia force when the plunger part slides through the interior of the storage part. [3] The ultrafine bubble production device described in [2], in which the decompression valve includes a sealing part, a valve body, and an elastic member, the sealing part being configured to close the one end of the storage part, and including a through hole forming a ventilation path when the decompression valve is operated, the valve body being configured to close the through hole, the elastic member being configured to urge the valve body to cause the valve body to close the through hole. [4] The ultrafine bubble production device described in [3], in which the valve body is displaced by causing the elastic member to deform by the inertia force, and causes the through hole to open. [5] The ultrafine bubble production device described in [2], in which the decompression valve includes a sealing part and a valve body, the sealing part being configured to close the one end of the storage part, and including a through hole forming a ventilation path when the decompression valve is operated, the valve body being configured to close the through hole and detach from the sealing part when the decompression valve is operated. [6] The ultrafine bubble production device described in any one of [3] to [5], in which a diameter of the valve body decreases in a direction in which the plunger part slides by using the energy. [7] The ultrafine bubble production device described in any one of [3] to [6], in which the ultrafine bubble production device includes a gap between the storage part and the drive part, the gap forming a portion of the ventilation path when the decompression valve is operated, and the ventilation path allows the storage space to communicate with outside air. [8] The ultrafine bubble production device described in any one of [1] to [7], in which the drive part includes an ignition part and a piston, the ignition part including an ignition agent that is ignited by an ignition current from outside, the piston being configured to push the plunger part into the storage part, the drive part being configured to apply combustion energy of the ignition agent to the piston. Advantageous Effects of Invention

[0008] According to the disclosed technique, the performance of the ultrafine bubble production device can be improved.Brief Description of Drawings

[0009] FIG. 1 is a vertical cross-sectional view illustrating an example of an ultrafine bubble production device. FIG. 2 is a diagram for describing an example of an initiator. FIG. 3 is a vertical cross-sectional view of the production device illustrating a state in which a piston has slid. FIG. 4 is a diagram for describing a plunger. FIG. 5 is a vertical cross-sectional view of the production device illustrating a state in which a decompression valve is opened. FIG. 6 is a vertical cross-sectional view of the production device illustrating a state in which a gap is formed between a plunger part and the piston. FIG. 7 is a vertical cross-sectional view illustrating an example of a production device according to a second embodiment. FIG. 8 is a vertical cross-sectional view of the production device illustrating a state in which the piston has slid. FIG. 9 is a vertical cross-sectional view of the production device illustrating a state in which the decompression valve is opened. Description of Embodiments

[0010] An embodiment will be described below with reference to the drawings. An embodiment of the present disclosure is an ultrafine bubble production device. The production device includes: a storage part in which a storage space for storing a liquid and a gas is formed, the storage part having one end to be closed; a drive part configured to generate energy for compressing the storage space and pressurizing and dissolving the gas in the liquid; and a plunger part configured to close the one end of the storage part, slide through an interior of the storage part by using the energy to compress the storage space, and after compressing the storage space, decompress the storage space to generate ultrafine bubbles.

[0011] In the present embodiment, "ultrafine bubbles" refer to bubbles having a diameter of less than 1 µm in accordance with discussions and definitions made by the Technical Committee TC281 (fine bubble technologies) of the International Organization for Standardization (ISO). Note that, although most of the bubbles produced by a production device 1 are ultrafine bubbles, it is only required that the bubbles produced by the production device 1 include ultrafine bubbles and the produced bubbles may include bubbles that do not satisfy the above-described definition.

[0012] In the present disclosure, the liquid stored in the storage part is not particularly limited. Examples of the liquid include liquids that can be used as a solvent (for example, water, alcohol, oil, and the like). Other examples of the liquid include solutions (for example, culture solutions (liquid culture media), saline, phosphate buffer solutions, prepared reagents, and cosmetics in the form of solutions). Other examples include emulsions (emulsion cosmetics such as milky lotion). The liquid may be a liquid containing any two or more of the above-mentioned liquids. Furthermore, the liquid may include a low-molecular-weight substance or a high-molecular-weight substance or may include an inorganic material or an organic material (for example, a biological substance such as a nucleic acid). In a preferred aspect of the present embodiment, the liquid is a liquid that does not include microorganisms or the like. In a preferred aspect of the present embodiment, the water is pure water (for example, distilled water, RO water, RO-EDI water, and ion-exchanged water), and in another preferred aspect, the water is ultrapure water. Examples of the ultrapure water include Milli-Q water.

[0013] In the present disclosure, the gas stored in the storage part is not particularly limited. Examples of the gas include air. Other examples can include nitrogen, oxygen, ozone, carbon dioxide, hydrogen, and carbon monoxide, as well as a mixed gas of any two or more of the above-mentioned gases. In a preferred aspect of the present embodiment, the gas is a gas that does not include microorganisms or the like. The air may be commonly used air, the composition of the air is not particularly limited. Examples of the air include a mixed gas containing about 80% nitrogen and about 20% oxygen.

[0014] In the present disclosure, an example of the form of applying energy by the drive part includes applying energy by using a known pressurization technique. The energy to be applied may be chemically generated energy such as combustion energy generated by an oxidation reaction of a low explosive or a high explosive, for example. As another method, the energy used for the change may be generated by electric power. In one example, energy generated by a piezoelectric element or an electromagnetic actuator driven by supplied electric power may be employed. Furthermore, as yet another method, the energy used for the change may be generated physically. In one example, elastic energy produced by an elastic body or internal energy from a compressed body, such as compressed gas, may be employed. For example, the drive part may release the pressure of a compressed gas to generate energy. In yet another method, the energy used for the change may be generated manually (by human power). For example, the drive part may transmit human power of an operator to apply energy to a valve body. That is, the energy used for the change may be any form of energy by which a piston can be pushed. Furthermore, the energy used for the change may be a composite-type energy obtained by appropriately combining the above-mentioned combustion energy, the energy generated by electric power, the internal energy such as the elastic energy, and the energy generated manually (by human power). For example, a compression spring may be compressed by human power to obtain a repulsive force of the compression spring.First Embodiment

[0015] FIG. 1 is a vertical cross-sectional view illustrating an example of an ultrafine bubble production device. An ultrafine bubble production device (hereinafter referred to as "production device") 1 according to the present embodiment includes a storage part 2 having a space therein, a drive part 3 that generates energy used for compressing an internal space of the storage part 2, and a plunger part 4 that compresses the internal space of the storage part 2. A liquid 5 and a gas 6 are stored in the internal space of the storage part 2. The plunger part 4 instantaneously pressurizes the inside of the storage part 2 by using the energy generated by the drive part 3, and causes at least a portion of the gas 6 to dissolve in the liquid 5. The production device 1 rapidly reduces the pressure in the storage part 2 to generate ultrafine bubbles from the supersaturated solution. The storage part 2 and the drive part 3 may be connected by a coupling member 7. The shape and the material of the coupling member 7 are not particularly limited, as long as the coupling member 7 can fix the storage part 2 and the drive part 3. In a state in which the storage part 2 and the drive part 3 are connected to each other, a gap may be formed between the storage part 2 and the drive part 3.

[0016] The storage part 2 is, for example, a tubular member with one end open and the other end closed. The storage part 2 includes a storage space 21 in which the liquid 5 and the gas 6 are stored. The one end of the storage part 2 that is open is closed by the plunger part 4. On the one end side of the storage part 2, the cross-sectional shape of the storage space 21 is constant. The plunger part 4 that has substantially the same cross-sectional shape as the storage space 21 slides through the interior of the storage part 2 and thus reduces the volume of the storage space 21. The material of the storage part 2 is not particularly limited, as long as the material can withstand the pressurization in the storage part.

[0017] The drive part 3 includes a tubular enclosure 31, an initiator (ignition part) 32 provided on one end side of the enclosure 31, a piston 33 slidably disposed inside the enclosure 31, and a cap 34 that is provided on the other end side of the enclosure and prevents the piston 33 from detaching. The initiator 32 generates energy used for sliding the piston 33. A combustion chamber 35 is formed inside the enclosure 31 between the initiator 32 and the piston 33. A gas generating agent may be stored in the combustion chamber 35. The piston 33 slides through the interior of the enclosure 31 by the energy generated by the initiator 32. The cap 34 includes an opening portion at the center in the cross section, and a portion of the piston 33 protrudes from the opening portion when the drive part 3 is operated.

[0018] For example, the initiator 32 is an electric ignition device. FIG. 2 is a diagram for describing an example of the initiator 32. The initiator 32 includes a storage cup 321, an ignition agent 322, a metal header 323, a charge holder 324, a bridge wire 325, two electro-conductive pins 326, and a resin collar 327. The electro-conductive pins 326 are connected to a power supply. The storage cup 321 is a member made of metal and covered with an insulating cover, and is a cup-shaped container whose one end is open. The ignition agent 322 is a low explosive and is stored in the storage cup 321. The metal header 323 is disposed on the open side of the storage cup 321, and the tubular charge holder 324 is provided on an inner side of the storage cup 321. A storage chamber 328 is formed on the inner side of the storage cup 321, the metal header 323, and the charge holder 324. The ignition agent 322 is sealed in the storage chamber 328. The bridge wire 325 that electrically connects one of the electro-conductive pins 326 with the metal header 323 is wired in the storage chamber 328. Note that the two electro-conductive pins 326 are fixed to the metal header 323 via an insulator 329, and thus the two electro-conductive pins 326 are in an insulated state from each other. Furthermore, the opening portion of the storage cup 321 is protected by the resin collar 327 in a state in which the insulating properties between the electro-conductive pins 326 are maintained. When a voltage is applied between the two electro-conductive pins 326 by an external power supply, a current flows through the bridge wire 325. Furthermore, the ignition agent 322 is ignited by the current and combusted. Thus, a combustion product such as a flame and a combustion gas generated by the combustion ruptures the storage cup 321 and is discharged into the combustion chamber 35 (FIG. 1).

[0019] The ignition agent 322 may be, for example, any one of a low explosive containing zirconium and potassium perchlorate (ZPP), a low explosive containing titanium hydride and potassium perchlorate (THPP), a low explosive containing titanium and potassium perchlorate (TiPP), a low explosive containing aluminum and potassium perchlorate (APP), a low explosive containing aluminum and bismuth oxide (ABO), a low explosive containing aluminum and molybdenum oxide (AMO), a low explosive containing aluminum and copper oxide (ACO), and a low explosive containing aluminum and iron oxide (AFO), or a low explosive obtained by combining plural types of the above-mentioned low explosives. These low explosives are characterized in that a combustion product thereof is gas at high temperatures, but these low explosives do not contain a gas component at ordinary temperature. Therefore, the combustion product is condensed immediately after the ignition. Accordingly, in the process of pressurizing the liquid and the gas, the temperature and the pressure of the combustion product during the pressurization generated by the combustion of an ignition agent can be shifted closer to the ordinary temperature and pressure in a short period of time after the pressure applied to the liquid and the gas reaches the first peak injection force.

[0020] The combustion chamber 35 may store a gas generating agent that generates gas by combustion. An example of the gas generating agent includes a single-base smokeless explosive composed of 98 mass% of nitrocellulose, 0.8 mass% of diphenylamine, and 1.2 mass% of potassium sulfate. Furthermore, various types of gas generating agents used in a gas generator for an air bag and a gas generator for a seat belt pretensioner can be used. By adjusting the amount, shape, size, and arrangement of the gas generating agent, the pressure generated inside the combustion chamber 35 can be appropriately adjusted.

[0021] The piston 33 includes a first portion 331 and a second portion 332 whose outer diameter is smaller than that of the first portion 331. The material of the piston 33 is also not particularly limited. The outer diameter of the first portion 331 is substantially equal to the inner diameter of the enclosure 31. Furthermore, a groove portion for holding an O-ring 333 is provided in the periphery of the first portion 331, and the outer periphery of the first portion 331 is connected to the inside of the enclosure 31 via the O-ring 333. The second portion 332 extends from the first portion 331 in a sliding direction of the piston 33. A tip end side of the second portion 332 contacts the plunger part 4, and pushes the plunger part 4 into the storage part 2 when the piston 33 slides. The outer diameter of the second portion 332 is smaller than the opening portion formed in the cap 34. The outer diameter of the first portion 331 is larger than the opening portion formed in the cap 34. Furthermore, an O-ring 334 is also disposed at a position adjacent to the first portion 331 in the periphery of the second portion 332. The enclosure 31 and the cap 34 include screw parts that are screwed to each other, and are connected to each other via an O-ring 335 in an airtight manner.

[0022] FIG. 3 is a vertical cross-sectional view of the production device 1 illustrating a state in which the piston 33 has slid. When a voltage is applied to the initiator 32, the ignition agent in the interior is combusted, and a combustion product is released into the combustion chamber 35. When the pressure inside the combustion chamber 35 rises by the combustion product of the initiator 32 or by further combustion of the gas generating agent stored in the combustion chamber 35, the piston 33 slides through the interior of the enclosure 31. The piston 33 can slide through the interior of the enclosure 31 at most until the first portion 331 (more precisely, the O-ring 334 adjacent to the first portion 331) contacts the cap 34. Furthermore, as the piston 33 slides, the plunger part 4 is pushed into the storage part 2, and the storage space 21 is compressed. At this time, the gas 6 stored in the storage space 21 is dissolved in the liquid 5, and a solution 51 is generated.

[0023] The plunger part 4 closes the one end of the storage part 2 that is open and compresses the storage space 21. At least a part of the plunger part 4 functions as a decompression part used for decompressing the storage space 21. FIG. 4 is a diagram for describing the plunger part 4. FIG. 4(A) is a perspective view of the plunger part 4 seen from above. FIG. 4(B) is a perspective view of the plunger part 4 seen from below. FIG. 4(C) is a vertical cross-sectional view of the plunger part 4. The plunger part 4 includes a sealing part 41 having a through hole, a valve body 42 disposed penetrating the sealing part 41, and a spring 43 disposed between the sealing part 41 and the valve body 42. The material of the sealing part 41 is, for example, resin, but the material is not limited thereto. For example, the material of the valve body 42 and the spring 43 is metal, but the material is not limited thereto.

[0024] The outer diameter of the sealing part 41 is substantially equal to the inner diameter of the storage part 2. Two groove portions for holding O-rings 411 are provided in the periphery of the sealing part 41, and the outer periphery of the sealing part 41 is connected to the inside of the storage part 2 via the two O-rings 411. The sealing part 41 has a through hole at the center in a cross section and functions as a valve seat. In a state in which the sealing part 41 is inserted into the storage part 2, the through hole allows the storage space 21 to communicate with the outside. The sealing part 41 includes a first region 412 in which the inner diameter of the through hole is substantially equal to that of a first portion 421 of the valve body 42, a second region 413 in which the inner diameter of the through hole is substantially equal to the outer diameter of the spring 43, and a third region 414 in which the inner diameter of the through hole is substantially equal to the outer diameter of a second portion 422 of the valve body 42.

[0025] The valve body 42 includes the first portion 421 and the second portion 422. After the second portion 422 is inserted into the through hole of the sealing part 41 and the spring 43, the second portion 422 is connected to the first portion 421 to assemble the valve body 42. A receiving hole 4211 for connecting the first portion 421 to one end side of the second portion 422 is formed inside the first portion 421 on a side of one end 4213. The receiving hole 4211 and the one end side of the second portion 422 are engaged with each other, and thus are not detached from each other. In a lateral peripheral portion of the receiving hole 4211, a slit 4212 is provided that is obtained by being cut in an axial direction of the first portion 421. One end of the slit 4212 is continuous to the one end 4213 of the first portion 421. A protruding portion 4214 is formed along a circumferential direction on the outer periphery of the first portion 421. The other end of the slit 4212 extends past the protruding portion 4214. The other end side of the second portion 422 includes an end portion 4221 whose diameter in a cross section is larger than the through hole of the sealing part 41, and a protruding portion 4222 whose outer diameter is substantially equal to the inner diameter of the through hole of the sealing part 41. An O-ring 4223 is held in a groove portion between the end portion 4221 and the protruding portion 4222. The outer periphery of the end portion 4221 is tapered, and the diameter thereof decreases toward a tip end.

[0026] Examples of the spring 43 include a compression coil spring that expands and contracts in the axial direction of the plunger part 4. However, the spring 43 may be an elastic member other than the compression coil spring. The outer diameter of the first portion 421 of the valve body 42 is larger than the outer diameter of the spring 43. The inner diameter of the third region 414 of the sealing part 41 is smaller than the outer diameter of the spring 43. Therefore, the spring 43 applies a force by which a step portion 416, located between the second region 413 and the third region 414 of the sealing part 41, and the one end 4213 of the first portion 421 are pushed against each other. That is, in a state before the production device 1 starts operating, the spring 43 urges the valve body 42 to cause the valve body 42 to close the through hole of the sealing part 41.

[0027] FIG. 5 is a vertical cross-sectional view of the production device 1 illustrating a state in which a decompression valve is opened. When the plunger part 4 is pushed by the piston 33 and slides, and subsequently collides with a stored object (the liquid 5) in the storage part 2, the valve body 42 slides, against the spring force of the spring 43, within the through hole of the sealing part 41 by the inertia force generated when the plunger part 4 slides. The diameter of the end portion 4221 of the valve body 42 decreases toward the tip end. This decreases the resistance when the valve body 42 enters the liquid 5 in the storage space 21, and helps the valve body 42 to slide easily. Furthermore, the valve body 42 preferably has a relatively large mass, because in this case, the kinetic energy when the valve body 42 enters the liquid 5 in the storage space 21 increases. For example, the valve body 42 may be made of metal such as brass.

[0028] The valve body 42 slides within the through hole of the sealing part 41, and thus, causes the through hole of the sealing part 41 to open. In FIG. 5, a through hole 4224 is open in the periphery of the second portion 422 of the valve body 42. At this time, the storage space 21 of the storage part 2 and a space between the piston 33 and the sealing part 41 communicate with each other via a ventilation path formed by the through hole 4224 and the slit 4212 of the valve body 42. The plunger part 4 and the piston 33 are not coupled to each other, and after the plunger part 4 collides with the stored object (the liquid 5), the contact surfaces are separated from each other by the impact, and a gap is formed between the plunger part 4 and the piston 33. FIG. 6 is a vertical cross-sectional view illustrating a state in which a gap is formed between the plunger part 4 and the piston 33. For example, a gap may be provided between the storage part 2 and the drive part 3, as indicated by reference sign 8. That is, the outer diameter of the second portion 332 of the piston 33 is smaller than the inner diameter of the storage space 21 of the storage part 2, and a ventilation path can be formed between the slit 4212 and the gap 8. Thus, the storage space 21 communicates with the outside air when the valve body 42 slides.

[0029] As described above, the sealing part 41, the valve body 42, and the spring 43 function as a decompression part (decompression valve) used for decompressing the storage space 21. Note that the weight of the sealing part 41 and the valve body 42, the spring force of the spring 43, the magnitude of the energy generated by the drive part 3, and the like can be appropriately set according to, for example, the volume of the storage part 2, and the content. In the decompression part described above, the pressure in the storage space 21 can be rapidly reduced, and ultrafine bubbles can be precipitated (generated) from a solution 52 in a supersaturated state in which an amount of the gas 6 equal to or greater than the solubility of the gas 6 is dissolved in the liquid 5.

[0030] The slit 4212 extends to a length at which the slit 4212 is not accommodated in the sealing part 41, even in a state in which the spring 43 is compressed to the maximum extent, and thus secures the ventilation path. For example, the protruding portion 4214 may be provided as a restricting portion that restricts the sliding of the valve body 42. The protruding portion 4214 may collide with the sealing part 41 to restrict the sliding of the valve body 42. At this time, the ventilation path may be secured by the slit 4212 extending past the protruding portion 4214. Furthermore, a step 415 may be provided between the first region 412 and the second region 413 of the sealing part 41, as a restricting portion that restricts the sliding of the valve body 42. The step 415 may collide with the one end 4213 of the first portion 421 of the valve body 42, and thus restrict the sliding of the valve body 42. Also at this time, the slit 4212 may secure the ventilation path.

[0031] For example, after the ultrafine bubbles are generated, the storage part 2 is detached from the drive part 3, and then, the plunger part 4 is detached from the inside of the storage part 2. Subsequently, the content including the ultrafine bubbles stored in the storage space 21 is discharged. At least a part of the production device 1, such as the storage part 2 and the plunger part 4, may be a disposable unit.

[0032] In general, when generating fine bubbles by a pressure-dissolving method, the concentration of fine bubbles is affected by the speed of a decompression step performed after dissolving a gas in a liquid by pressurization. In the present embodiment, the number of ultrafine bubbles to be generated can be increased (that is, the size of the bubbles can be prevented from increasing) by rapidly reducing the pressure by the decompression part. According to the present embodiment, 100 billion ultrafine bubbles / ml or more can be generated. The number and particle diameter of the ultrafine bubbles were measured and analyzed by using NanoSight (Spectris Co., Ltd.). In the present embodiment, the ultrafine bubbles are generated in the storage space 21 in an airtight state. Thus, the present embodiment is suitable for the generation of ultrafine bubbles in a closed system such as a sterile environment.Second Embodiment

[0033] FIG. 7 is a vertical cross-sectional view illustrating an example of a production device according to a second embodiment. FIG. 8 is a vertical cross-sectional view of the production device illustrating a state in which the piston 33 has slid. FIG. 9 is a vertical cross-sectional view of the production device illustrating a state in which the decompression valve is opened. Note that constituent members corresponding to those in the first embodiment are denoted by corresponding reference signs, and description thereof will be omitted.

[0034] A plunger part 4A of a production device 1A according to the present embodiment includes a valve body 42A that is press-fitted into a sealing part 41A having a through hole 417, instead of the valve body 42 and the spring 43 described in the first embodiment. The through hole 417 in the sealing part 41A is formed along the axial direction of the plunger part 4A. For example, the material of the sealing part 41A according to the present embodiment is also resin, but the material is not limited thereto. The valve body 42A is a shaft-shaped member including an O-ring 4223A on a lateral periphery of the valve body 42A. The O-ring 4223A provides sealing between the valve body 42A and the sealing part 41A, and improves the airtightness of the storage space 21. For example, the material of the valve body 42A is metal such as brass, but the material is not limited thereto.

[0035] As illustrated in FIG. 8, in the production device 1A, the piston 33 pushes the plunger part 4A by the energy generated by the drive part 3, and thus, the storage space 21 is pressurized. The valve body 42A according to the present embodiment is press-fitted in such a manner that the valve body 42A can be detached from the through hole 417 of the sealing part 41A during operation of the production device 1A. As illustrated in FIG. 9, when the plunger part 4A is pushed by the piston 33 and slides, and subsequently collides with a stored object (the liquid 5) in the storage part 2, the valve body 42A detaches from the sealing part 41A by the inertia force generated when the plunger part 4A slides. Note that the diameter of the valve body 42A according to the present embodiment also decreases toward the tip end, and the resistance when the valve body 42A enters the liquid 5 in the storage space 21 decreases. The valve body 42A also preferably has a relatively large mass, because in this case, the kinetic energy when the valve body 42A enters the liquid 5 in the storage space 21 increases.

[0036] By using the O-ring 4223A, the valve body 42A can be reliably detached from the sealing part 41A. However, the valve body 42A may be directly press-fitted into the sealing part 41A without using the O-ring 4223A. In this case, in a portion where the valve body 42A and the sealing part 41A contact each other, at least one of the valve body 42A or the sealing part 41A may be made of elastic material. Furthermore, an engaging portion such as recesses and protrusions may be provided to engage the valve body 42A and the sealing part 41A with each other.

[0037] The production device 1A according to the second embodiment functions as a decompression valve when the valve body 42A detaches from the sealing part 41A. That is, the through hole 417 in the sealing part 41A serves as a ventilation path, and allows the storage space 21 to communicate with a space 36 in the piston 33 and the like. Furthermore, by reducing the pressure inside the storage space 21, the number of ultrafine bubbles to be generated can be increased. In the production device 1A according to the second embodiment, a larger cross-sectional area of the ventilation path can be ensured than that in the first embodiment for an amount that the valve body 42A is detached from the through hole 417 (in other words, the valve body 42A does not remain in the through hole 417). Therefore, the pressure inside the storage space 21 can be reduced more rapidly than in the first embodiment. The valve body 42A has a simpler structure than the valve body 42 in the first embodiment. Thus, the valve body 42A contributes to a reduction in the manufacturing cost and an improvement in the durability of the device, and can ensure that the device operates more reliably.Modified Examples

[0038] Each of the configurations, combinations thereof, and the like in each of the embodiments is an example, and additions, omissions, substitutions, and other changes of the configurations may be made as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited by the embodiments and is limited only by the claims. Each embodiment disclosed in the present specification can be combined with any other feature disclosed herein.

[0039] The drive part 3 is not limited to the above-described configuration. For example, the drive part 3 may release the pressure of a compressed gas to generate energy.Reference Signs List

[0040] 1, 1A: Production device 2: Storage part, 21: Storage space 3: Drive part, 31: Enclosure, 32: Initiator, 33: Piston, 34: Cap, 35: Combustion chamber 4, 4A: Plunger part, 41, 41A: Sealing part, 42, 42A: Valve body, 4212: Slit, 43: Spring 5: Liquid 6: Gas

Claims

1. An ultrafine bubble production device comprising: a storage part in which a storage space configured to store a liquid and a gas is formed, the storage part having one end to be closed; a drive part configured to generate energy used for compressing the storage space and pressurizing and dissolving the gas in the liquid; and a plunger part configured to close the one end of the storage part, slide through an interior of the storage part by using the energy to compress the storage space, and after compressing the storage space, decompress the storage space to generate ultrafine bubbles.

2. The ultrafine bubble production device according to claim 1, wherein the plunger part includes a decompression valve that is opened by an inertia force when the plunger part slides through the interior of the storage part.

3. The ultrafine bubble production device according to claim 2, wherein the decompression valve includes a sealing part, a valve body, and an elastic member, the sealing part being configured to close the one end of the storage part and including a through hole forming a ventilation path when the decompression valve is operated, the valve body being configured to close the through hole, the elastic member being configured to urge the valve body to cause the valve body to close the through hole.

4. The ultrafine bubble production device according to claim 3, wherein the valve body is displaced by causing the elastic member to deform by the inertia force, and causes the through hole to open.

5. The ultrafine bubble production device according to claim 2, wherein the decompression valve includes a sealing part and a valve body, the sealing part being configured to close the one end of the storage part, and including a through hole forming a ventilation path when the decompression valve is operated, the valve body being configured to close the through hole and detach from the sealing part when the decompression valve is operated.

6. The ultrafine bubble production device according to any one of claims 3 to 5, wherein a diameter of the valve body decreases in a direction in which the plunger part slides by using the energy.

7. The ultrafine bubble production device according to any one of claims 3 to 5, wherein the ultrafine bubble production device includes a gap between the storage part and the drive part, the gap forming a portion of the ventilation path when the decompression valve is operated, and the ventilation path allows the storage space to communicate with outside air.

8. The ultrafine bubble production device according to any one of claims 1 to 5, wherein the drive part includes an ignition part and a piston, the ignition part including an ignition agent that is ignited by an ignition current from outside, the piston being configured to push the plunger part into the storage part, the drive part being configured to apply combustion energy of the ignition agent to the piston.

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