Fluid sterilization apparatus

Abstract

To provide a fluid sterilizing device equipped with a small and lightweight flow passage pipe.SOLUTION: The fluid sterilization device includes a flow passage tube 20 through which a fluid flows, and a light source part 30 for irradiating the inside of the flow passage tube 20 with ultraviolet rays. The flow path tube 20 includes a transparent tube 21 that transmits ultraviolet rays, and a reflector 22 that is provided in contact with the outer peripheral surface of the transparent tube 21, reflects ultraviolet rays transmitted through the transparent tube 21, and is an unsintered PTFE film. The reflector 22 is a laminate in which a plurality of unsintered PTFE films are laminated, and the front surface of the unsintered PTFE film located on the inner side and the back surface of the unsintered PTFE film located on the outer side are disposed in close contact with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluid disinfection device. [Background technology]

[0002] Sterilization devices that kill bacteria and viruses in running water by irradiating it with ultraviolet light are known. Mercury lamps are widely used as the light source. Mercury lamps have the problem of being highly toxic and having a large environmental impact because they contain mercury. Another problem is that the sterilization device becomes large when mercury lamps are used. Therefore, efforts are underway to replace mercury lamps with ultraviolet LEDs.

[0003] Patent documents 1 to 4 show water sterilization devices that use ultraviolet LEDs. Patent documents 1 to 3 show a configuration in which a window that can transmit ultraviolet light is provided at one end of a tube through which water flows, and an ultraviolet-emitting LED package is placed behind the window.

[0004] It is also known that sterilization efficiency can be improved by using PTFE (polytetrafluoroethylene), which has high ultraviolet reflectivity, as a flow path pipe and reflecting ultraviolet rays inside the flow path pipe. Patent Documents 1 and 2 show flow path pipes in which PTFE material is provided on the inner surface of a pipe made of a resin material, a metal material, or the like. Patent Document 3 shows a flow path pipe in which the inside is made of an ultraviolet-transmitting material and the outside is made of PTFE.

[0005] Patent Document 4 describes a structure in which a metal pedestal protrudes into the inside of a flow path pipe, a mounting board on which an ultraviolet light emitting element is mounted is placed on the pedestal, a metal cap is provided to cover the ultraviolet light emitting element, and an ultraviolet light transmitting window is provided in the cap. It also describes that the pedestal and cap are exposed to the flow path, and that heat can be dissipated from the pedestal and cap to the liquid. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2016-523594 [Patent Document 2] Japanese Patent Publication No. 2022-69596 [Patent Document 3] International Publication No. 2018 / 143304 [Patent Document 4] Patent Publication No. 2021-41382 Summary of the Invention [Problem to be solved by the invention]

[0007] Traditionally, PTFE bulk has been widely used for flow pipes. However, PTFE bulk is difficult to mold and process, which requires long processing times and is costly. It is also difficult to make PTFE bulk thinner while maintaining its reflectivity and strength, making it difficult to miniaturize flow pipes.

[0008] The present invention has been made in view of the above background, and aims to provide a fluid sterilizing device equipped with a small flow path pipe. [Means for solving the problem]

[0009] One aspect of the present invention is A fluid sterilization device having a flow path pipe through which a fluid flows and a light source unit that irradiates the inside of the flow path pipe with ultraviolet light, The flow path pipe is a transparent tube that transmits the ultraviolet light; The fluid sterilization device has a reflector, which is an unsintered PTFE film and is provided in contact with the outer peripheral surface of the transparent tube to reflect the ultraviolet light that has passed through the transparent tube. [Effects of the Invention]

[0010] In the above fluid sterilization device, the reflector is a laminate of PTFE unsintered membrane, which can be easily manufactured by wrapping the PTFE unsintered membrane around a transparent tube. In addition, the unsintered membrane can be made very thin, which allows the flow path tube to be made smaller.

[0011] As described above, according to the above aspect, it is possible to provide a fluid sterilizing device equipped with a small flow path pipe. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing the configuration of a fluid sterilization device in embodiment 1, taken along a plane including an axis. [Figure 2] FIG. 2 is an exploded view of the fluid sterilization device according to the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing the configuration of the light source unit, taken along a plane including an axis. [Figure 4] A diagram showing the heat distribution in a cross section of a plane including the axis near the light source. [Figure 5] Graph showing the relationship between water flow rate (L / min) and inactivation rate (Log). [Figure 6] A diagram showing the heat distribution in a cross section of a plane including the axis near the light source. [Figure 7] Graph showing the relationship between thickness and reflectance for unsintered and sintered PTFE. [Figure 8] Graph showing the relationship between thickness and reflectance for unsintered PTFE. [Figure 9] 10 is a graph showing the relationship between the reflectance of a reflector of a flow path pipe and the irradiation dose. [Figure 10] A graph showing the relationship between the thermal conductivity of the package case and the junction temperature. [Figure 11] A graph showing the relationship between the thermal conductivity of the lid and the junction temperature. [Figure 12] 10 is a cross-sectional view showing the configuration in the vicinity of the LED package in the second modified embodiment, taken along a plane including the axis. FIG. [Figure 13] FIG. 11 is a cross-sectional view showing the configuration in the vicinity of the LED package in the third modified embodiment, taken along a plane including the axis. [Figure 14] FIG. 11 is a cross-sectional view showing the configuration in the vicinity of the LED package in Modification 4, taken along a plane including the axis. [Figure 15] FIG. 13 is a cross-sectional view showing the configuration in the vicinity of the LED package in the fifth modified embodiment, taken along a plane including the axis. [Figure 16] 13 is a cross-sectional view showing the configuration in the vicinity of the LED package in the sixth modified embodiment, taken along a plane including the axis. FIG. [Figure 17] FIG. 10 is a cross-sectional view showing the configuration of a fluid sterilization device in embodiment 2, taken along a plane including an axis. [Figure 18] 10 is a graph showing the relationship between the thermal conductivity of the mounting substrate and the junction temperature in the second embodiment. [Figure 19] FIG. 10 is a cross-sectional view perpendicular to the axis of the fluid sterilizing device according to the third embodiment, taken along a plane passing through the light source unit. [Figure 20] FIG. 11 is a cross-sectional view of a fluid sterilization device according to a third embodiment, taken along a plane including an axis thereof. DETAILED DESCRIPTION OF THE INVENTION

[0013] The fluid sterilization device has a flow path pipe through which a fluid flows and a light source unit that irradiates ultraviolet light into the inside of the flow path pipe. The flow path pipe has a transparent tube that transmits ultraviolet light and a reflector that is an unsintered PTFE film that is provided in contact with the outer surface of the transparent tube and reflects the ultraviolet light that has transmitted through the transparent tube.

[0014] The reflector may be a laminate of a plurality of unsintered PTFE films, and the surface of the inner unsintered PTFE film may be in close contact with the back surface of the outer unsintered PTFE film. The unsintered PTFE film may be a self-fusing tape.

[0015] The reflector may have a thickness of 0.02 mm or more, and may have a thickness thinner than that of the transparent tube.

[0016] The transparent tube may have a refractive index of 1.3 to 1.5, and the fluid may be mainly composed of water. The transparent tube may also be a quartz tube.

[0017] The reflector may have a direct contact portion that is in direct contact with the outer peripheral surface of the transparent tube and reflects ultraviolet light that has passed through the transparent tube, and an air layer interposed portion that is arranged between the reflector and the outer surface of the transparent tube with a partial air layer interposed therebetween and reflects ultraviolet light that has passed through the transparent tube and the air layer.

[0018] The transparent tube may further include a cylindrical housing that houses the flow path tube and the light source unit arranged in the axial direction, and a seal ring that is housed inside the housing and is positioned in contact with each of the one end face and the other end face in the axial direction of the flow path tube, and that restricts the ingress of fluid between the inner surface of the housing and the outer surface of the transparent tube.

[0019] (Embodiment 1) 1. Overview of the configuration of the fluid sterilization device 1 FIG. 1 is a cross-sectional view showing the configuration of a fluid sterilization device 1 in embodiment 1, taken along a plane including the axis of the fluid sterilization device 1. FIG. 2 is an exploded view of the fluid sterilization device 1 in embodiment 1. As shown in FIGS. 1 and 2, the fluid sterilization device 1 in embodiment 1 has a housing 10, a flow path pipe 20, a light source unit 30, a spacer 40, and a plate 50. The light source unit 30 has an LED package 31, a mounting board 32, a sealing unit 33, and a light source case 34. The LED package 31 has an LED 35, a package case 36, and a lid unit 37.

[0020] The fluid sterilization device 1 of the first embodiment is a device that sterilizes water by flowing it through the flow path pipe 20 and the spacer 40 and irradiating it with ultraviolet light. The internal space of the flow path pipe 20 and the spacer 40 is the flow path space 70 (the space through which water flows during sterilization and the area irradiated with ultraviolet light). In addition to water, any liquid such as oil or alcohol can be sterilized. A solid may be mixed into the liquid as long as it remains fluid.

[0021] 2. Details of each component of the fluid sterilization device 1 Next, each component of the fluid sterilization device 1 will be described in detail.

[0022] The housing 10 is cylindrical, with an inlet 11 at one axial end face and an outlet 12 on the side of the cylinder near the other end face. The housing 10 is made of a material such as black PP (polypropylene). Inside the housing 10, a plate 50, a flow path pipe 20, and a spacer 40 are coaxially arranged in this order from the inlet 11 side.

[0023] The other end face of the housing 10 is open. A screw thread 13 is provided on the inner peripheral surface of the tube near the other end face. A light source unit 30 is fitted into the other end face of the housing 10 and fastened with screws, and the other end face of the housing 10 is sealed by the light source unit 30.

[0024] O-rings 60 are provided between the housing 10 and the plate 50, between the plate 50 and the flow path pipe 20, and between the flow path pipe 20 and the spacer 40 to prevent water from leaking between the various components. Water that flows in from the inlet 11 passes through the plate 50, the flow path pipe 20, and the spacer 40, is irradiated with ultraviolet light by the light source unit 30, and is then discharged from the outlet 12.

[0025] The flow path pipe 20 is cylindrical and has a transparent tube 21 and a reflector 22 provided in contact with the outer peripheral surface of the transparent tube 21. The outer peripheral surface of the reflector 22 is in contact with the inner peripheral surface of the housing 10. The reflector 22 has a high reflectivity for ultraviolet light, and can reflect ultraviolet light off the side surface of the flow path pipe 20, allowing the ultraviolet light to be efficiently irradiated onto the water flowing through the flow path pipe 20.

[0026] The transparent tube 21 is a cylindrical tube made of quartz, and water to be sterilized flows through the inside of the tube.

[0027] The material of the transparent tube 21 is not limited to quartz, but may be any material that transmits ultraviolet light and has low absorptivity. For example, sapphire, ultraviolet-transmitting glass, fluororesin, acrylic resin, etc. may be used. In particular, a material with a small difference in refractive index from water is preferred, and in this respect, quartz in embodiment 1 is suitable. For example, a material with a refractive index of 1.3 to 1.5 is preferred.

[0028] The transparent tube 21 may have any thickness within a range that allows it to withstand water pressure and transmit ultraviolet light, for example, 0.4 to 3 mm. A material and thickness that allows ultraviolet light transmittance of 80% or more in the case of normal incidence is preferred.

[0029] It is preferable that the inner circumferential surface of the transparent tube 21 is as flat as possible, and for example, it is preferable that the RMS (root mean square height) is 1 μm or less. Bacteria are less likely to adhere to the unevenness of the inner circumferential surface, and the inner circumferential surface is less likely to become dirty, thereby preventing a decrease in sterilization efficiency. In addition, a water-repellent coating such as a fluororesin may be formed on the inner circumferential surface of the transparent tube 21, making the inner circumferential surface of the transparent tube 21 water-repellent and preventing the inner circumferential surface of the transparent tube 21 from becoming dirty.

[0030] The reflector 22 is provided in contact with the outer peripheral surface of the transparent tube 21. The reflector 22 reflects ultraviolet light that passes through the transparent tube 21 and heads outward.

[0031] The reflector 22 is formed by wrapping an unsintered PTFE (polytetrafluoroethylene) film around the outer circumferential surface of the transparent tube 21 one or more times. In other words, the reflector 22 is a laminate (laminate) in which the unsintered PTFE film is laminated on the transparent tube 21. The unsintered PTFE film is a film in the form of a sheet or tape, which is formed by rolling unsintered PTFE fine powder. The PTFE fine powder is a white powder formed by agglomerating fine PTFE particles.

[0032] For example, the PTFE fine powder can be powder for paste extrusion molding (II-1 or II-2) specified in JIS K 6896:1995. II-1 satisfies the following properties: apparent density (g / ml) 0.50±0.15, moisture (%) 0.04 or less, high-temperature volatile content (%) 0.1 or less, melting point (°C) 327±10, specific gravity 2.13 to 2.20, tensile strength (MPa) 17.6 or more, and elongation (%) 200 or more. These properties are measured according to JIS K 6896:1995. II-2 has the same properties as II-1, except for the specific gravity of 2.18 to 2.28.

[0033] Furthermore, the PTFE unsintered film may be an unsintered film manufactured using powder for paste extrusion molding specified in JIS K 6896:1995 and containing no additives. In particular, a PTFE unsintered tape specified in JIS K 6885:2005 may be used. The PTFE unsintered tape specified in JIS K 6885:2005 satisfies the following qualities: apparent density (g / cm 3 ) is 1.0 or more, tensile strength (MPa) is 7.0 or more, elongation (%) is 20 or more, volatile loss (%) is 0.5 or less, and it is non-flammable. The measurement method for these qualities is in accordance with JIS K 6885:2005.

[0034] The unsintered PTFE film has self-adhesive properties because it is unsintered. Therefore, when the unsintered PTFE film is wrapped around the transparent tube 21, there is no gap between the transparent tube 21 and the unsintered PTFE film, and no gap between the unsintered PTFE films. Therefore, the unsintered PTFE film can be adhered and fixed to the transparent tube 21 without using adhesives or the like, and the reflector 22 can be easily formed.

[0035] Note that a partial air layer may remain in the gap between the transparent tube 21 and the unsintered PTFE film, or between the unsintered PTFE films. Even if an air layer remains, reflection occurs due to the difference in refractive index at the interface with the air layer, and ultraviolet light that passes through the air layer is reflected by the unsintered PTFE film, so this does not significantly affect the ultraviolet reflectance of the reflector 22. Therefore, when forming the reflector 22 by wrapping the unsintered PTFE film around the transparent tube 21, it is not necessary to wrap it tightly so as to eliminate any air layers, and the reflector 22 can be formed easily.

[0036] The reflector 22 has a high reflectivity for ultraviolet light. This is due to the following reasons: First, PTFE itself is a material with high ultraviolet reflectivity. Second, the self-bonding properties of the PTFE unsintered film prevent gaps from forming between the transparent tube 21 and the PTFE unsintered film, and between the PTFE unsintered films. Third, PTFE fine powder becomes fibrous when shear stress is applied, so the particles of the PTFE unsintered film are fibrous, resulting in a high particle density.

[0037] The thickness of the reflector 22 is preferably 0.02 mm or more, and the number of turns of the PTFE unsintered film should be set to achieve this thickness. This allows for a reflectance equal to or greater than that of barium sulfate, a common reflective material. In particular, the thickness of the reflector 22 is preferably 0.2 mm or more. This allows for a UV reflectance equal to or greater than that achieved when the flow path tube 20 is made of PTFE bulk with a thickness of 8 mm. While there is no upper limit to the thickness of the reflector 22, UV reflectance saturates as the thickness increases, so it is preferable to set it to 2 mm or less. The thickness of the reflector 22 may also be thinner than that of the transparent tube 21. The thickness and width of the PTFE unsintered film may be arbitrary, but may also be values ​​specified in JIS K 6885:2005.

[0038] O-rings 60 are disposed on both ends of the flow path pipe 20. This prevents water from entering between the outer circumferential surface of the transparent tube 21 and the inner circumferential surface of the housing 10, more specifically, between the outer circumferential surface of the transparent tube 21 and the inner circumferential surface of the reflector 22, and between the outer circumferential surface of the reflector 22 and the inner circumferential surface of the housing 10.

[0039] The light source unit 30 is cylindrical, and a screw thread 38 is provided on the side of the cylinder (the side of a light source case 34 described below). This screw thread 38 corresponds to the screw thread 13 of the housing 10. The light source unit 30 is fitted into the open end face of the housing 10, and is screwed in place by fitting the screw thread 38 into the screw thread 13. The light source unit 30 is also arranged at one axial end of the flow path pipe 20 via a spacer 40.

[0040] The light source unit 30 emits ultraviolet light, which enters the spacer 40 and the inside of the flow path pipe 20 from one end of the spacer 40. This allows the spacer 40 and the water flowing through the flow path pipe 20 to be sterilized by being irradiated with ultraviolet light. The detailed configuration of the light source unit 30 will be described later.

[0041] The spacer 40 is disposed between the flow path pipe 20 and the light source unit 30. The spacer 40 is a cylindrical tube made of PTFE and is disposed coaxially with the flow path pipe 20. The spacer 40 is provided to efficiently reflect ultraviolet rays emitted from the light source unit 30 that form a large angle with respect to the axis, thereby increasing the efficiency of irradiation of ultraviolet rays onto the water.

[0042] The plate 50 is disposed between the inlet 11 of the housing 10 and the flow path pipe 20. The plate 50 is disk-shaped and disposed coaxially with the flow path pipe 20. The plate 50 is made of PTFE. By using PTFE, which has high UV reflectivity, UV rays that reach the end face of the flow path pipe 20 on the inlet 11 side are reflected back into the flow path pipe 20, increasing the efficiency of UV irradiation of the water. The plate 50 has multiple through-holes. The water flowing in from the inlet 11 is dispersed by passing through the multiple through-holes of the plate 50 and then flows into the flow path pipe 20.

[0043] Although the fluid sterilizer 1 of the first embodiment is cylindrical, it may have any shape as long as it allows water to flow through it. For example, it may be formed into a cylindrical shape such as a square tube.

[0044] 3. Details of each component of the light source unit 30 Next, the configuration of the light source unit 30 will be described in detail with reference to the drawings.

[0045] 3 is a cross-sectional view showing the configuration of the light source unit 30, taken along a plane including the axis of the light source unit 30. As shown in FIG. 3, the light source unit 30 is cylindrical, and includes an LED package 31, a mounting substrate 32, a sealing portion 33, and a light source case 34.

[0046] The LED package 31 is mounted on a mounting substrate 32. The LED package 31 has an LED (light emitting element) 35, a package case 36 that houses the LED 35, and a lid 37 that seals the package case 36 and transmits ultraviolet light.

[0047] The LED 35 is a light emitting element that emits ultraviolet light. The wavelength of the ultraviolet light is preferably 250 to 285 nm, which is a wavelength that has a high sterilizing effect on water. A plurality of LEDs 35 may be provided in one LED package 31.

[0048] The package case 36 is in the shape of a box, such as a rectangular parallelepiped or cylinder, with an open top. Two electrodes are formed on the inner and outer bottom surfaces of the box, and the electrodes are connected between the inside and outside. The outer bottom surface of the package case 36 is mounted on the mounting board 32, and the electrodes on the outer bottom surface are connected to the circuit of the mounting board 32. An LED 35 is housed inside the package case 36, and the LED 35 is arranged on the inner bottom surface of the box so as to connect to the two electrodes. The shape of the package case 36 is not limited to a box shape, and may be any shape that has an internal space for housing the LED 35 and an opening that opens to the internal space.

[0049] The package case 36 is made of ceramic. Ceramics such as aluminum nitride and aluminum oxide, which have high UV reflectance and thermal conductivity, are particularly preferred. Alternatively, metals with high thermal conductivity, such as Cu and Al, may be used. The package case 36 may also be made of a material with a higher thermal conductivity than that of the mounting substrate 32. This allows for more efficient heat conduction from the LED 35 to the lid 37 via the package case 36, improving heat dissipation efficiency. For the same reason, the package case 36 is preferably made of ceramic or metal with a thermal conductivity of 10 W / m·K or higher.

[0050] The lid 37 is a flat plate and is disposed so as to cover the opening of the package case 36. The lid 37 and the package case 36 are joined with resin or solder. The lid 37 seals the opening of the package case 36 to enclose the LED 35, and also functions as a window that transmits ultraviolet light from the LED 35. The lid 37 is made of sapphire.

[0051] The surface of the lid 37 is in contact with the flow path space 70. Therefore, the surface of the lid 37 comes into direct contact with water during sterilization.

[0052] Although the entire surface of the lid 37 does not need to be in contact with the flow path space 70, it is preferable that the entire surface be in contact. Also, the side surface of the lid 37 may be in contact with the flow path space 70.

[0053] The lid 37 is not limited to a flat plate shape, but may be a convex lens shape. A convex lens shape narrows the directivity of the ultraviolet light emitted from the LED package 31, allowing the ultraviolet light to be more efficiently irradiated onto the water. A convex lens shape is particularly suitable when there is a large difference in the refractive index between the material of the lid 37 and the refractive index of water.

[0054] The material for the lid 37 is not limited to sapphire and can be any material that transmits ultraviolet light emitted from the LED 35. However, a material with a thermal conductivity of 0.25 W / m·K or higher is preferred to improve heat dissipation efficiency. For example, quartz, borosilicate glass, fluororesin, etc. can be used. A material with high thermal conductivity is preferred to improve heat dissipation efficiency, and sapphire is preferably used as in embodiment 1. The lid 37 may also be made of a material with a higher thermal conductivity than that of the mounting substrate 32. This allows for more efficient heat conduction from the LED 35 through the package case 36 to the lid 37, improving heat dissipation efficiency.

[0055] The thickness of the lid 37 is preferably 0.1 mm or more. This increases the heat spread and the heat dissipation area, allowing for more efficient heat dissipation to the water via the lid 37. However, if the lid 37 is too thick, the thermal resistance increases, so it is preferable to set the area and thickness of the lid 37 to achieve appropriate heat dissipation characteristics.

[0056] It is also possible to provide a plurality of LED packages 31. In the first embodiment, since the heat of the LED packages 31 can be efficiently dissipated, when a plurality of LED packages 31 are provided, the distance between the LED packages 31 can be shortened, and the light source unit 30 can be made compact.

[0057] The mounting substrate 32 is a substrate on which the LED package 31 is mounted. A circuit-forming member 80 electrically connected to the LED package 31 is mounted on the mounting substrate 32. The circuit-forming member 80 includes a drive circuit for driving the LED package 31 and a connector header for connecting the drive circuit to a power cable. In addition, the mounting substrate 32 is provided with a thermistor for measuring the temperature of the mounting substrate 32, a connector header for connecting the thermistor to a power cable, and the like.

[0058] In the first embodiment, no heat sink is provided on the back surface of the mounting substrate 32. Therefore, electronic components and circuits may be mounted on the back surface of the mounting substrate 32. For example, only the LED package 31 may be mounted on the front surface of the mounting substrate 32, and electronic components other than the LED package 31 may be mounted on the back surface. By mounting on both sides, the area of ​​the mounting substrate 32 can be reduced, and the light source unit 30 can be made smaller.

[0059] The mounting substrate 32 is made of aluminum. Any other material can be used. Conventionally, a heat sink was connected to the back surface of the mounting substrate 32, and therefore the mounting substrate 32 was made of a material with high thermal conductivity, such as aluminum. On the other hand, in embodiment 1, the mounting substrate 32 is not a main heat dissipation path, as will be described later, so the mounting substrate 32 may have low thermal conductivity. In other words, embodiment 1 provides a wider range of material options for the mounting substrate 32. For example, a glass epoxy substrate such as FR-4 or CEM3, or a flexible substrate made of polyimide, etc., may be used. Furthermore, the mounting substrate 32 may be subjected to various processes, such as drilling.

[0060] The light source case 34 is cylindrical and holds the mounting substrate 32 therein. The light source case 34 is made of PP. Alternatively, SUS or other materials may be used. An opening 34b is provided on the top surface (the surface on the spacer 40 side) of the light source case 34 to allow ultraviolet light from the LED package 31 to pass through. Inside the light source case 34, the mounting substrate 32 is arranged so that the opening 34b faces the LED package 31. The width of the opening 34b is, for example, equal to or greater than the width of the lid portion 37. The top surface of the lid portion 37 is arranged so as to be flush with the bottom surface of the opening 34b.

[0061] Furthermore, a protrusion 34a is provided on the outer upper surface of the light source case 34. The protrusion 34a contacts the spacer 40. This protrusion 34a creates a gap between the upper surface of the light source case 34 and the spacer 40, allowing water from the spacer 40 to flow through this gap to the outlet 12. This gap also serves as a flow path space 70, and is in contact with the lid 37.

[0062] A screw thread 38 is provided on the outer peripheral surface of the light source case 34. The screw thread 38 corresponds to the screw thread 13 provided on the inner peripheral surface of the housing 10. The light source unit 30 fitted into the housing 10 is screwed in by the screw thread 38 engaging with the screw thread 13 of the housing 10. Of course, the light source unit 30 may be fixed to the housing 10 by a method other than screwing.

[0063] The sealing portion 33 is a caulking material formed to fill the gap between the mounting substrate 32 and the light source case 34. The sealing portion 33 is made of a waterproof polymer material such as urethane resin, silicone resin, or epoxy resin. The sealing portion 33 fills up to the upper inner surface of the light source case 34, covering the lower part of the LED package 31 and the circuit-forming member 80, such as the drive circuit of the mounting substrate 32, and preventing the connection portion between the LED package 31 and the mounting substrate 32 and the circuit-forming member 80 from coming into contact with water. The outer surface of the lid portion 37 is not covered by the sealing portion 33 and is in contact with the flow path space 70.

[0064] The sealing portion 33 may be mixed with thermally conductive particles or thermally conductive fibers. By imparting high thermal conductivity to the sealing portion 33, heat from the LED package 31 can be more easily dispersed through the sealing portion 33, thereby improving heat dissipation. In particular, it is preferable to use a highly thermally conductive material for the light source case 34, such as metal, and to use highly thermally conductive materials for both the sealing portion 33 and the light source case 34. Since the light source case 34 is in contact with the flow path space 70, the light source case 34 comes into direct contact with water, allowing heat to be dissipated from the sealing portion 33 to the water via the light source case 34. This further improves heat dissipation. The sealing portion 33 may be in contact with the flow path space 70, allowing heat to be dissipated from the sealing portion 33 to the water.

[0065] 4. Heat dissipation path Next, the heat dissipation path of heat generated from the LED package 31 will be described. When water is introduced from the inlet 11 and flows through the flow path pipe 20 and the spacer 40, and ultraviolet light is irradiated from the light source unit 30 onto the water for sterilization, heat is generated from the LEDs 35 of the light source unit 30. The heat generated from the LEDs 35 is conducted to the package case 36 and then from the package case 36 to the lid unit 37. Here, the lid unit 37 is disposed so as to contact the flow path space 70, and therefore comes into direct contact with the water flowing between the spacer 40 and the light source case 34. Therefore, heat is efficiently conducted from the lid unit 37 to the water. In this way, in the first embodiment, the heat generated from the LEDs 35 can be efficiently dissipated to the water.

[0066] The seal portion 33 contacts both the package case 36 and the light source case 34, and the light source case 34 contacts the flow path space 70. Therefore, a heat dissipation path is also formed in which heat is conducted in the following order: package case 36, seal portion 33, light source case 34, and water. Heat dissipation through this heat dissipation path becomes effective when the seal portion 33 is made of a material containing thermally conductive particles to enhance thermal conductivity.

[0067] Furthermore, when the seal portion 33 is in contact with the flow path space 70, a heat dissipation path is also formed in which heat is conducted from the package case 36 to the seal portion 33 and then to water. Heat dissipation through this heat dissipation path is also effective when the thermal conductivity of the seal portion 33 is increased.

[0068] 5. Summary of effects As described above, in the fluid sterilization device 1 of embodiment 1, heat generated by the LEDs 35 can be efficiently dissipated from the lid 37 to the water. This eliminates the need to provide a heat dissipation structure such as a heat sink on the back surface of the mounting substrate 32, allowing for a more compact and lightweight device. Furthermore, because the lid 37 of the LED package 31 is in direct contact with the water, ultraviolet light is efficiently incident on the water, improving sterilization efficiency. Furthermore, because a window separating the LED package 31 and the flow path pipe 20 is not required, the window does not fog up, preventing a decrease in ultraviolet light irradiation efficiency.

[0069] Furthermore, in the fluid sterilization device 1 of embodiment 1, there is no need to use a material with high thermal conductivity for the mounting substrate 32 or to provide a heat dissipation structure such as a heat sink on the back surface of the mounting substrate 32. This allows the mounting substrate 32 to be made of a material with low thermal conductivity, facilitating processes such as drilling holes in the mounting substrate 32 and double-sided mounting, thereby increasing the degree of freedom in shape.

[0070] Furthermore, in the fluid sterilization device 1 of embodiment 1, the flow path pipe 20 uses a reflector 22, which is a laminate of a transparent tube 21 and an unsintered PTFE film. This makes it possible to easily increase the ultraviolet reflectance on the side surface of the flow path pipe 20. Furthermore, the diameter of the flow path pipe 20 can be reduced while maintaining the same sterilization efficiency as a conventional flow path pipe using PTFE bulk.

[0071] The effect of the flow path pipe 20 in the first embodiment on the PTFE bulk will be described in detail below.

[0072] First, the flow path pipe 20 in the first embodiment can be formed more easily than bulk PTFE.

[0073] PTFE bulk is a molded product made by adding additives to PTFE powder, filling it into a mold, compressing it to remove voids and densifying it, and then sintering it, and it comes in shapes such as blocks, rods, pipes, etc. However, PTFE bulk is not easy to mold and process, and the processing time is long, resulting in high costs.

[0074] On the other hand, in the flow path pipe 20 of embodiment 1, the UV reflectance of the flow path pipe 20 can be easily improved simply by wrapping the PTFE unsintered film around the transparent tube 21. The transparent tube 21 and the PTFE unsintered film are adhered to each other by the self-adhesive properties of the PTFE unsintered film. Therefore, no adhesive is required. While adhesives can deteriorate due to UV rays, causing peeling or cracking, the flow path pipe 20 does not use an adhesive, so there is no need for such concerns. Furthermore, since there is no light absorption by the adhesive, a higher reflectance can be obtained. Furthermore, since the PTFE unsintered film is on the outer surface of the transparent tube 21, there is no possibility that the PTFE unsintered film will be physically damaged by water pressure.

[0075] Secondly, the flow path pipe 20 in the first embodiment has a higher ultraviolet reflectance than bulk PTFE, and can be made compact.

[0076] The PTFE bulk is relatively thick to increase UV reflectivity, and to make it smaller, the inner diameter must be reduced, but this increases the number of reflections on the inner surface, resulting in greater light loss and reduced sterilization efficiency.

[0077] In contrast, the PTFE unsintered film has a higher UV reflectivity than PTFE bulk when compared at the same thickness, so the thickness of the flow path pipe 20 in embodiment 1 can be made thinner than when the flow path pipe 20 is made of PTFE bulk, allowing for a more compact flow path pipe 20. In addition, the difference in refractive index between quartz, the material of the transparent tube 21, and water is small, preventing UV rays reflected by the PTFE unsintered film from being reflected back at the interface between the quartz and water. This improves the reflectivity of the flow path pipe 20 as a whole.

[0078] The reflectance of PTFE bulk is lower than that of unsintered PTFE membrane because there are gaps between the crystal grains in PTFE bulk, allowing some UV light to penetrate into the PTFE bulk and be scattered by the crystal grain structure, etc. On the other hand, the crystal grains in unsintered PTFE membrane are dense, which prevents UV light from penetrating into the unsintered PTFE membrane, resulting in a high reflectance.

[0079] Thirdly, the flow path pipe 20 in the first embodiment is less susceptible to staining on the inner wall surface than PTFE bulk, and the decrease in sterilization efficiency is suppressed.

[0080] PTFE bulk is a sintered powder molded product manufactured by machining, resulting in fine irregularities on the inner circumferential surface. This made the inner circumferential surface prone to contamination. In particular, bacteria could adhere to the irregularities and grow, forming a biofilm. When the inner circumferential surface of the flow path pipe 20 becomes contaminated, the ultraviolet reflectance decreases, resulting in a decrease in sterilization efficiency.

[0081] On the other hand, the transparent tube 21 is made of quartz, and the inner surface can be easily processed to be flat. Therefore, the inner surface of the transparent tube 21 is less likely to become dirty, and the decrease in sterilization efficiency due to dirt is suppressed.

[0082] Fourth, according to the flow path pipe 20 of the first embodiment, ultraviolet rays can reach farther in the axial direction than in the case of PTFE bulk, and the efficiency of sterilizing water can be improved.

[0083] In PTFE bulk, ultraviolet rays propagate in the axial direction while being reflected by the inner wall surface of the PTFE bulk, but the entire propagation path is water. Therefore, ultraviolet rays do not reach far in the axial direction due to attenuation caused by reflection in the PTFE bulk and attenuation caused by absorption of ultraviolet rays by water.

[0084] On the other hand, in the flow path tube 20 of embodiment 1, the refractive index of quartz, which is the material of the transparent tube 21, is close to that of water. Therefore, UV light is not reflected at the interface between the transparent tube 21 and the water flowing inside the tube, and most of it is reflected at the interface between the transparent tube 21 and the reflector 22 and propagates in the axial direction of the flow path tube 20. Therefore, UV light propagates not only through the water but also within the transparent tube 21. Because the transparent tube 21 is made of quartz, it absorbs UV light less than water. Thus, in the case of the flow path tube 20, the UV light propagation path includes not only water but also quartz. As a result, UV light can propagate farther than in the case of PTFE bulk, which propagates only water. This effect is particularly effective when sterilizing water that is cloudy against UV light.

[0085] 6. Experimental Examples Related to Embodiment 1 Various experimental examples relating to the fluid sterilizing device 1 in the first embodiment will be described.

[0086] Experimental Example 1 For the fluid sterilizer 1 of embodiment 1, a current of 350 mA was applied to the LED 35, and the heat distribution was determined by simulation. The heat distribution was determined for three patterns: air cooling (no water flow) and water cooling (water flow with flow rates of 0.6 L / min and 1.0 L / min). The water temperature was set to 20.5°C.

[0087] Figure 4 shows the heat distribution in a cross section of the light source unit 30, taken along a plane including the axis. The arrows in Figure 4 indicate the direction of heat conduction. Figure 4(a) shows the case of air cooling, (b) shows the case of water cooling with a flow rate of 0.6 L / min, and (c) shows the case of water cooling with a flow rate of 1.0 L / min. As shown in Figure 4(a), with air cooling, the mounting board 32 became very hot, and the junction temperature (maximum temperature of the LED 35) was 247°C. On the other hand, as shown in Figures 4(b) and 4(c), with water flow, the temperature of the mounting board 32 decreased, and the junction temperature was 61.2°C at a flow rate of 0.6 L / min and 59.0°C at a flow rate of 1 L / min. These results demonstrate that heat can be efficiently dissipated from the lid 37 to the water.

[0088] Experimental Example 2 The junction temperature was measured for the fluid sterilizer 1 of embodiment 1. The water temperature was set to 25.2°C. When the flow rate was 1 L / min and the current of the LED 35 was 350 mA, the junction temperature was 60.7°C. When the flow rate was 0.6 L / min and the current of the LED 35 was 350 mA, the junction temperature was 64.3°C. The actual measurements also confirmed that the fluid sterilizer 1 of embodiment 1 was able to efficiently dissipate heat from the lid 37 to the water.

[0089] Experimental Example 3 The sterilization performance of the fluid sterilization device 1 in the first embodiment was evaluated. The reflector 22 of the flow path pipe 20 was made of the unsintered PTFE_A film shown in Experimental Example 5 and FIGS. 7 and 8, which will be described later, and had a thickness of 0.4 mm. 5 The inactivation rate (Log) was measured using water containing a concentration of CFU / mL. Measurements were performed twice and the average value was calculated. The LED35 current was 350 mA, the output was 62 mW, and the wavelength was 280 nm. The water flow rate was set to three levels: 0.6 L / min, 0.8 L / min, and 1.0 L / min.

[0090] Figure 5 is a graph showing the relationship between the water flow rate (L / min) and the inactivation rate (Log). As shown in Figure 5, the inactivation rate was 3.5 Log at a flow rate of 1.0 L / min, 4.6 Log at a flow rate of 0.8 L / min, and 5.6 Log at a flow rate of 0.6 L / min. At all flow rates, the inactivation rate was 3 Log or higher, indicating high sterilization performance. As a result, it was found that the fluid sterilization device 1 of embodiment 1 also achieved sufficient sterilization performance.

[0091] Experimental Example 4 The material of the mounting board 32 was changed to FR-4 (glass epoxy board) (Experimental Example 4-1), and the heat distribution was obtained by simulation in the same manner as in Experimental Example 1. The water flow rate was set to 1 L / min. The heat distribution was also obtained in the same manner when the thickness of the mounting board 32 was reduced (t = 1.6 mm) and embedded in the sealing portion 33 (Experimental Example 4-2), and when the mounting board 32 was made of FR-4 and the light source case 34 was changed from PP to SUS (Experimental Example 4-3).

[0092] FIG. 6 shows the heat distribution in a cross section of a plane including the axis near the light source unit 30. FIG. 6(a) shows Experimental Example 4-1, FIG. 6(b) shows Experimental Example 4-2, and FIG. 6(c) shows Experimental Example 4-3. As shown in FIG. 6, it was found that the temperature of the mounting board 32 decreased in all cases. Furthermore, the junction temperature was 63.3°C in Experimental Example 4-1, 62.2°C in Experimental Example 4-2, and 58.9°C in Experimental Example 4-3. This result indicates that heat can be efficiently dissipated from the lid unit 37 to the water. It was also found that heat dissipation is possible regardless of the materials of the mounting board 32 and the light source case 34. This indicates that the mounting board 32 and the light source case 34 are not the main heat dissipation paths in the first embodiment.

[0093] Experimental Example 5 The UV reflectance of unsintered PTFE and sintered PTFE was measured at each thickness. The wavelength was 280 nm, and the reflectance was expressed as a relative value (%) to a BaSO4 standard reflector. Three types of unsintered PTFE samples (Unsintered PTFE_A-C) from different manufacturers were prepared, and four types of sintered PTFE samples (Sintered PTFE_A-D) from different manufacturers were prepared.

[0094] Figures 7 and 8 are graphs showing the relationship between PTFE thickness and reflectivity. As shown in Figures 7 and 8, unsintered PTFE has a high reflectivity even at a thickness thinner than sintered PTFE, and sufficient reflectivity was obtained at a thickness of 1 mm or less. The maximum reflectivity of sintered PTFE was achieved with sintered PTFE_C at a thickness of 8 mm, but unsintered PTFE_B had a higher reflectivity than sintered PTFE_C at a thickness of 0.2 mm or more. This indicates that a thickness of 0.2 mm or more is preferable for unsintered PTFE.

[0095] Experimental Example 6 The relationship between the reflectance of the reflector 22 of the flow path pipe 20 and the irradiation dose was determined by simulation when the flow rates were 1.0 L / min, 0.8 L / min, and 0.6 L / min in the structure of Experimental Example 1. For the reflector 22, unsintered PTFE_A 0.4 mm with a reflectance of 105.2% as shown in Figures 7 and 8 was used.

[0096] The results are shown in Figure 9. The irradiation dose at a reflectance of 105.2% for each flow rate is approximately 9.5 mJ / cm 2 , 12 mJ / cm 2 , 16 mJ / cm 2 Therefore, the inactivation rate of 3 Log is approximately 8 mJ / cm 2 This is considered to correspond to the above. The reflectivity of the reflector 22 of the flow path pipe 20 to obtain a sterilization performance with an inactivation rate of 3 Log at each flow rate is approximately 84% at 0.6 L / min, approximately 96% at 0.8 L / min, and approximately 102% at 1.0 L / min. From Figure 8, these conditions can be met with a film thickness of 0.1 mm at 1.0 L / min, 0.04 mm at 0.8 L / min, and 0.01 mm at 0.6 L / min.

[0097] Experimental Example 7 For the fluid sterilization device 1 in the first embodiment, the thermal conductivity of the package case 36 was changed to various values, and the junction temperature was determined by simulation under the same conditions as in the first experimental example.

[0098] Figure 10 is a graph showing the relationship between the thermal conductivity of the package case 36 and the junction temperature. As shown in Figure 10, it was found that the junction temperature decreases as the thermal conductivity of the package case 36 increases. Since the maximum junction temperature of a typical UV LED is 100 to 150°C, it was found that sufficient heat dissipation can be achieved by setting the thermal conductivity of the package case 36 to 10 W / m·K or higher.

[0099] Experimental Example 8 For the fluid sterilization device 1 in the first embodiment, the thermal conductivity of the lid 37 was changed to various values, and the junction temperature was determined by simulation under the same conditions as in the first experimental example.

[0100] Figure 11 is a graph showing the relationship between the thermal conductivity of the lid 37 and the junction temperature. As shown in Figure 11, it was found that the junction temperature decreases as the thermal conductivity of the lid 37 increases. Since the maximum junction temperature of a typical UV LED is 100 to 150°C, it was found that sufficient heat dissipation can be achieved by setting the thermal conductivity of the lid 37 to 0.25 W / m K or higher.

[0101] (Modification 1 of Embodiment 1) In the first embodiment, the top surface of the lid portion 37 (the surface opposite to the LED 35 side) is arranged to be flush with the bottom surface of the opening 34b (the surface on the LED 35 side), but any arrangement is possible as long as the top surface of the lid portion 37 is not covered by the seal portion 33. For example, the top surface of the lid portion 37 may be arranged so that it is inside the opening 34b, or so that the top surface of the lid portion 37 is closer to the spacer than the outer upper surface of the light source case 34. Since the area of ​​the LED package 31 that contacts the flow path space 70 is wider, the heat dissipation efficiency is also improved.

[0102] (Modification 2 of Embodiment 1) 12 shows a second modified example of the first embodiment, and is a cross-sectional view taken along a plane including the axis, showing the configuration in the vicinity of the LED package 31. However, the circuit-forming member 80 is not shown.

[0103] 12 , in modified embodiment 2, the LED package 31 protrudes toward the spacer 40, so that a portion of the package case 36 is positioned closer to the spacer 40 than the light source case 34. Not only the top surface of the lid 37, but also the side surfaces of the lid 37 and the outer peripheral side surfaces (excluding the lower end) of the package case 36 are not covered by the seal portion 33 and are in contact with the flow path space 70. As a result, when water is introduced into the flow path pipe 20, not only the lid 37 but also the side surfaces of the package case 36 come into direct contact with the water. Therefore, not only a heat dissipation path from the lid 37 to the water but also a heat dissipation path from the package case 36 to the water is formed, and the heat dissipation area is increased, thereby improving heat dissipation efficiency.

[0104] (Variation 3 of Embodiment 1) FIG. 13 shows a third modified example of the first embodiment, a cross-sectional view showing the configuration around the LED package 31, taken along a plane including the axis. In the third modified example, the package case 36 in the second modified example is filled with a sealing member 90 to seal the LED 35. The interior may be completely or partially filled. The sealing member 90 contacts the lid 37 and the package case 36. The sealing member 90 may be any material that transmits ultraviolet light and has a higher thermal conductivity than air. It may be a liquid such as oil or resin, or a solid such as cured resin or glass. The thermal conductivity of the sealing member 90 is preferably 0.1 W / m·K or higher.

[0105] In the third modified embodiment, a path for heat conduction is created from the LED 35 to the lid 37 and package case 36 via the sealing member 90, so that heat can be dissipated more efficiently.

[0106] (Fourth Variation of First Embodiment) FIG. 14 shows a fourth modified example of the first embodiment, and is a cross-sectional view showing the configuration in the vicinity of the LED package 31, taken along a plane including the axis.

[0107] As shown in FIG. 14, in the fourth modified embodiment, the package case 36 is replaced with a flat substrate 136, and the lid portion 37 is replaced with a lid portion 137 having a rectangular box shape.

[0108] The LED 35 is disposed on the substrate 136. The substrate 136 is preferably made of a material with high ultraviolet reflectivity and high thermal conductivity, such as the same material as the package case 36. A portion of the side surface of the substrate 136 is not covered by the seal portion 33 and comes into direct contact with water.

[0109] The lid 137 has a rectangular box shape and includes an internal space and an opening. The lid 137 is disposed on the substrate 136 so as to seal the LED 35 within the internal space. That is, the lid 137 is disposed on the substrate 136 with the opening facing the substrate 136, and the LED 35 is disposed on the substrate 136 so as to be inside the lid 137. The substrate 136 and the lid 137 are bonded together with an adhesive. This seals the LED 35 within the lid 137. The top and side surfaces of the lid 137 are not covered by the sealant 33 and are in direct contact with water. The shape of the lid 137 is not limited to a rectangular parallelepiped shape, and may be any shape that has an internal space capable of sealing the LED 35 and an opening that opens to the internal space. For example, a hemispherical shell shape may be used. The internal space of the lid 137 may be filled with a sealing member 90, as in the second modification.

[0110] In the fourth modified embodiment, heat can be dissipated from the top and side surfaces of the lid 37 and the substrate 136 to the water, and the heat dissipation area is increased, thereby improving the heat dissipation efficiency.

[0111] The lid 137 and the LED 35 may be sealed together by glass sealing or the like to prevent any internal space from forming. In this case, heat can be conducted directly from the LED 35 to the lid 137, allowing for efficient heat dissipation. The substrate 136 and the lid 137 may also be integrated using the same material.

[0112] (Variation 5 of Embodiment 1) The seal portion 33 may have a two-layer structure consisting of a first seal portion 33A and a second seal portion 33B. FIG. 15 shows the case where the two-layer structure is used in the second modified embodiment. As shown in FIG. 15, the first seal portion 33A is provided on the surface of the mounting substrate 32 and in the gap between the LED package 31 and the mounting substrate 32. This waterproofs the circuit formation member 80 on the mounting substrate 32 and the connection portion between the LED package 31 and the mounting substrate 32, and improves adhesion between the LED package 31 and the mounting substrate 32. The second seal portion 33B is provided to fill the gap between the first seal portion 33A and the light source case 34.

[0113] The first seal portion 33A is substantially not exposed to ultraviolet light from the LED 35. Therefore, any material that adheres to the mounting substrate 32 and is waterproof is sufficient; UV resistance is not necessary. Furthermore, as long as the second seal portion 33B is waterproof and UV resistant, adhesion to the mounting substrate 32 is not a major issue. By providing the seal portion 33 with a two-layer structure consisting of the first seal portion 33A and the second seal portion 33B, it is possible to select materials suited to the respective functions, thereby broadening the range of material options. For example, fluororesin, EPDM (ethylene propylene rubber), liquid gasket, etc. can be used for the first seal portion 33A.

[0114] (Variation 6 of Embodiment 1) 16, in modified embodiment 6, the second seal portion 33B may be omitted, and a gasket 133 may be provided between the first seal portion 33A and the light source case 34. The gasket 133 seals the mounting substrate 32 to prevent water from getting into the side or back side. In modified embodiment 6, the contact area between the LED package 31 and water can be increased, improving heat dissipation efficiency.

[0115] (Embodiment 2) Figure 17 is a cross-sectional view showing the configuration of a fluid sterilization device 2 of embodiment 2, taken along a plane including an axis. As shown in Figure 17, the fluid sterilization device 2 of embodiment 2 is a straight-tube type device in which an outlet 216 is provided coaxially with the inlet 11 on the opposite side of the light source unit 30 from the inlet 11. Of the reference symbols in Figure 17, the same reference symbols as those used in embodiment 1 represent the same components as in embodiment 1, unless otherwise specified. As shown in Figure 17, the fluid sterilization device 2 of embodiment 2 has housings 210, 215, flow path pipes 20, 220, a light source unit 230, a spacer 40, and plates 50, 250.

[0116] The housing 210 is similar to the housing 10 of the first embodiment, except that it does not have the exhaust port 12. The light source unit 230 is similar to the light source unit 30, except that it has a through-hole 39 that passes through the light source unit 30 in the axial direction, and that it uses a mounting board 232 instead of the mounting board 32. The through-hole 39 is located so as not to pass through the LED package 31. The mounting board 232 is a glass epoxy board, and is otherwise similar to the mounting board 32 of the first embodiment. The mounting board 232 is not limited to a glass epoxy board, and may be any board that is easy to drill holes in.

[0117] The housing 215 is provided on the back surface of the light source unit 30 (the surface opposite to the spacer 40 side). The housing 215 is cylindrical, with one end surface open and joined to the back surface of the light source unit 30. An outlet 216 is provided on the other end surface. The outlet 216 is arranged coaxially with the inlet 11. Inside the housing 215, a plate 250 and a flow path pipe 220 are arranged coaxially in this order from the outlet 216 side, and the flow path pipe 220 is in contact with the back surface of the light source unit 30. In addition, O-rings 60 are provided between the housing 215 and the plate 250, and between the plate 250 and the flow path pipe 220. The plate 250 is similar to the plate 50 except for its diameter. The material of the housing 215 is, for example, PP, and may be the same material as the housing 210.

[0118] The flow path pipe 220 is cylindrical and is disposed coaxially with the axis of the housing 215. The flow path pipe 220 is a pipe that guides water from the through-hole 39 of the light source unit 230 to the outlet 216. Since the flow path pipe 220 is not irradiated with ultraviolet light, any material may be used for the flow path pipe 220. For example, stainless steel or quartz glass may be used. Note that the flow path pipe 220 and the plate 250 may not be provided as long as they can sufficiently withstand the water pressure.

[0119] In the second embodiment, water that flows in through the inlet 211 of the housing 210 flows through the plate 50, the flow path pipe 20, and the spacer 40 in this order, then passes through the through-hole 39 of the light source unit 230 to the back side of the light source unit 30, flows through the flow path pipe 220 and the plate 250, and is discharged from the outlet 216 of the housing 215. Here, as in the first embodiment, ultraviolet light from the light source unit 30 is irradiated onto the water flowing through the spacer 40 and the flow path pipe 20, and the water is sterilized.

[0120] The fluid sterilizer 2 of embodiment 2 can achieve the same effects as the fluid sterilizer 1 of embodiment 1. Conventionally, heat was dissipated by providing a heat sink on the back surface of the mounting substrate 32, which required the use of a highly thermally conductive material for the mounting substrate 232. However, in embodiment 2, heat can be efficiently dissipated from the lid portion 37, so there is no need to provide a heat sink on the back surface of the mounting substrate 232, and the mounting substrate 232 can be made of a material that is easy to process and has low thermal conductivity, such as a glass epoxy substrate. Therefore, as in the fluid sterilizer 2 of embodiment 2, the outlet 216 can be provided coaxially with the inlet 11 on the back surface of the mounting substrate 232, allowing it to be a straight-pipe type.

[0121] Experimental Example 8 For the fluid sterilization device 2 in the second embodiment, the thermal conductivity of the mounting substrate 232 was changed to various values, and the junction temperature was determined by simulation under the same conditions as in the first experimental example.

[0122] 18 is a graph showing the relationship between the thermal conductivity of the mounting substrate 232 and the junction temperature. As shown in FIG. 18, it was found that there was very little decrease in the junction temperature with an increase in the thermal conductivity of the mounting substrate 232. This indicates that the mounting substrate 232 does not act as a heat dissipation path. As a result, it was found that a material with low thermal conductivity can be used for the mounting substrate 232, and that it may be perforated or otherwise processed.

[0123] (Embodiment 3) 19 and 20 are diagrams showing the configuration of a fluid sterilization device 3 of embodiment 3. The fluid sterilization device 3 is cylindrical, and FIG. 19 is a cross-sectional view perpendicular to the axis of the cylinder, passing through the light source unit 330. FIG. 20 is a cross-sectional view taken along a plane including the axis of the cylinder. Of the reference symbols in FIGS. 19 and 20, those that are the same as those used in embodiments 1 and 2 represent the same components as those in embodiments 1 and 2, unless otherwise specified. As shown in FIGS. 19 and 20, the fluid sterilization device 3 of embodiment 3 has a housing 310, a flow path pipe 320, and a light source unit 330.

[0124] The housing 310 is cylindrical and has a flow path pipe 320 disposed therein. An outlet 312 is provided on the top surface of the cylinder of the housing 310. A through-hole that penetrates the housing 310 and the flow path pipe 320 is provided on the side of the housing 310, and serves as an inlet 311. The axis of the inlet 311 is perpendicular to the axis of the housing 310 and parallel to the tangent to the circumference of the cylinder. By setting the axis of the inlet 311 in this way, a flow of water within the flow path pipe 320 that rotates around the axis can be created. This allows the irradiation time of ultraviolet light on the water to be extended, improving the sterilization efficiency.

[0125] The flow path pipe 320 is cylindrical, and its interior is a flow path space 370, that is, a space through which water flows during sterilization and is an area to be irradiated with ultraviolet light. It has a transparent tube 321 and a reflector 322 provided in contact with the outer peripheral surface of the transparent tube 321. The reflector 322 is in contact with the inner peripheral surface of the housing 310. The transparent tube 321 and the reflector 322 are the same as the transparent tube 21 and the reflector 22 in the first embodiment. The reflector 322 has a high reflectivity for ultraviolet light, and can reflect ultraviolet light off the side surface of the flow path pipe 320, allowing the ultraviolet light to be efficiently irradiated onto the water flowing through the flow path pipe 320.

[0126] Through holes for fitting the light source unit 330 are provided on the side surfaces of the housing 310 and the flow path pipe 320. The axis of the through hole is perpendicular to the axis of the flow path pipe 320 and faces that axis. Three through holes are provided at equal intervals around the circumference of the cylinder.

[0127] The light source unit 330 is similar to the light source unit 30 of the first embodiment, except that the number of LED packages 31 is four and the threads 38 and the protrusions 34a are not provided on the side of the light source case 34. The LED packages 31 are arranged in a 2x2 matrix. The light source unit 330 is fitted into each of the three through holes so that the radiation direction of ultraviolet light is the axial direction of the flow path pipe 320. In addition, the lid portion 37 of each LED package 31 is arranged so as to be in contact with the flow space. Therefore, when water is introduced from the inlet 311, the lid portion 37 comes into direct contact with the water.

[0128] The fluid sterilization device 3 of the third embodiment can achieve the same effects as the fluid sterilization device of the first embodiment.

[0129] (Variation) As in the first to third embodiments, the LED package 31 may be disposed in any position as long as the lid 37 is disposed so as to be in contact with the flow path space. The positions of the inlet and outlet may also be arbitrary, and the positions of the inlet and outlet may be interchanged in the first to third embodiments.

[0130] Although the sterilization of liquids has been described in the first to third embodiments, any fluid can be sterilized, and it is also possible to sterilize gases, mixtures of gases and liquids, mixtures of gases and powdery solids, and the like. [Explanation of symbols]

[0131] 10, 210, 310: Housing 20, 220, 320: Flow pipe 21, 321: Transparent tube 22, 322: Reflector 30, 230, 330: Light source section 40: Spacer 50, 250: Plate 31: LED package 32: Mounting board 33: Seal part 34: Light source case 35: LED 36: Package case 37: Lid

Claims

1. A fluid sterilization device having a flow path pipe through which a fluid flows and a light source unit that irradiates the inside of the flow path pipe with ultraviolet light, The flow path pipe is a transparent tube that transmits the ultraviolet light; a reflector, which is an unsintered PTFE film, provided in contact with the outer peripheral surface of the transparent tube and reflects the ultraviolet light that has passed through the transparent tube.

2. The fluid sterilization device according to claim 1, wherein the reflector is a laminate of a plurality of the unsintered PTFE films, and the surface of the unsintered PTFE film located on the inside and the back surface of the unsintered PTFE film located on the outside are arranged in close contact with each other.

3. The fluid sterilization device of claim 2 , wherein the PTFE unsintered film is a self-fusing tape.

4. 4. The fluid sterilizing device according to claim 1, wherein the reflector has a thickness of 0.02 mm or more.

5. 4. The fluid sterilizing device according to claim 1, wherein the reflector has a thickness thinner than that of the transparent tube.

6. the transparent tube has a refractive index of 1.3 to 1.5; The fluid sterilizing device according to any one of claims 1 to 3, wherein the fluid is mainly water.

7. 7. The fluid sterilization device of claim 6, wherein the transparent tube is a quartz tube.

8. The reflector is a direct contact portion that is in direct contact with the outer peripheral surface of the transparent tube and that reflects the ultraviolet light that has passed through the transparent tube; The fluid sterilization device according to any one of claims 1 to 3, further comprising: an air layer interposition portion that is arranged with a partial air layer interposed between the transparent tube and an outer surface of the transparent tube, and that reflects the ultraviolet light that has passed through the transparent tube and the air layer.

9. a housing formed in a cylindrical shape and housing the flow path pipe and the light source unit arranged in an axial direction; The fluid sterilization device according to any one of claims 1 to 3, further comprising seal rings housed inside the housing and arranged in contact with each of one end face and the other end face in the axial direction of the flow path pipe, and which regulate the ingress of the fluid between the inner surface of the housing and the outer surface of the transparent tube.

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