Infrared heaters, fixed structures and drying ovens

Abstract

This invention relates to an infrared heater, a fixed structure, and a drying oven. The infrared heater comprises a heating element that radiates infrared rays when heated, an inner tube housing the heating element and forming a heating unit together with the heating element, and an outer tube housing the heating unit detachably. The inner and outer tubes are made of insulating inorganic material and function as low-pass filters absorbing infrared rays with wavelengths greater than 6 μm. The outer tube has a first end with an insertion port for inserting the heating unit. The heating unit has a third end disposed on the first end side and equipped with a power supply unit for supplying power to the heating element. The inner tube has a first flange portion disposed on the third end side and having a diameter larger than the outer diameter of the inner tube. The insertion port of the outer tube has a second flange portion that abuts against the first flange portion when the heating unit is housed inside the outer tube. A space for cooling fluid to flow is formed between the inner and outer tubes. The outer tube has a fluid supply port and a fluid discharge port.

Description

Technical Field

[0001] This invention relates to an infrared heater, a fixed structure for the infrared heater, and a drying oven equipped with an infrared heater. Background Technology

[0002] Drying ovens for continuous drying of coatings, such as electrode coatings for lithium-ion batteries or electrode coatings for solar power generation, are known. The coatings described above contain components such as water or organic solvents with intermolecular hydrogen bonds. Therefore, to improve the productivity of the drying oven, a large amount of heat needs to be radiated into the oven from an infrared heater to rapidly evaporate the water or organic solvents contained in the workpiece.

[0003] Therefore, a drying oven is known that suppresses the rise in temperature inside the oven and has excellent near-infrared radiation with a concentrated ability to break the hydrogen bonds between molecules on the workpiece, thereby enabling efficient and continuous heating and drying of coatings (e.g., JP2012132662A). Summary of the Invention

[0004] The problem that the invention aims to solve

[0005] Since the heating element of the infrared heater used in this type of drying oven is a consumable, it is required to be easy to maintain, such as easy to replace the heating element.

[0006] The purpose of this invention is to provide an infrared heater, a fixed structure for the infrared heater, and a drying oven equipped with the infrared heater. The infrared heater suppresses the rise in temperature inside the oven and provides near-infrared rays with excellent ability to irradiate the workpiece with concentrated radiation, thereby enabling efficient heating and drying of the coating film, and is easy to maintain.

[0007] Methods for solving problems

[0008] To address the aforementioned issues, the first aspect of the present invention relates to an infrared heater (1) comprising: a heating element (2) that radiates infrared rays when heated; an inner tube (4) that houses the heating element and together with the heating element constitutes a heating unit (3); and an outer tube (5) that detachably houses the heating unit. The infrared heater is characterized in that the inner tube and / or the outer tube are insulating inorganic material tubes that function as low-pass filters absorbing infrared rays with wavelengths greater than 6 μm. The outer tube has: a first end (5a) with an insertion port (51) for inserting the heating unit; and a second end (5b) located on the side opposite to the first end. The heating unit has: a third end (3a) disposed on the side of the first end and equipped with a device for radiating infrared rays to the heating unit. A power supply unit (91) for powering the heating element; and a fourth end (3b) disposed on the second end side, without a power supply unit installed. The inner tube has a first flange (41) disposed on the third end side and has a diameter (r2) larger than the outer diameter (r1) of the inner tube. The insertion port of the outer tube has a second flange (52) which abuts against the first flange when the heating unit is housed inside the outer tube. When the heating unit is housed inside the outer tube, a space (50) for cooling fluid to flow is formed between the inner tube and the outer tube. The outer tube has a fluid supply port (53) for supplying cooling fluid to the space from the outside and a fluid discharge port (54) for discharging cooling fluid from the space to the outside.

[0009] The second aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the inner tube and / or the outer tube are insulating inorganic material tubes that function as low-pass filters for absorbing infrared rays with wavelengths above 4.7 μm.

[0010] The third aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the outer tube has a cylindrical insertion hole (55) on the inner side of the second end for the fourth end of the heating unit to be inserted, the insertion hole having an inner diameter (r4) smaller than the inner diameter (r3) of the second end of the outer tube and larger than the outer diameter of the fourth end of the heating unit.

[0011] The fourth aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the infrared heater further comprises an O-ring disposed between the first flange portion of the inner tube and the second flange portion of the outer tube for sealing the insertion port.

[0012] The fifth aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the inner tube and / or the outer tube are provided with a reflective film (6) for reflecting infrared rays irradiated from the heating element and thus limiting the irradiation direction of the infrared rays.

[0013] The sixth aspect of the present invention is characterized in that, in the infrared heater of the fifth aspect, in a radial cross-section of the inner tube and the outer tube, the central angle α of the area where the reflective film is disposed is 90° or more and 180° or less.

[0014] The seventh aspect of the present invention is characterized in that, in the infrared heater of the fifth aspect, the inner tube and the outer tube are quartz tubes, and the reflective film is a gold film or an aluminum film.

[0015] The eighth aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the outer surface of the outer tube has a mounting hole (7) for mounting a thermocouple.

[0016] The ninth aspect of the present invention is characterized in that, in the infrared heater of the eighth aspect, the inner tube and the outer tube are arranged in a concentric circle in radial cross-section, the inner tube and / or the outer tube are provided with a reflective film (6) for reflecting infrared rays irradiated from the heating unit and limiting the irradiation direction of the infrared rays, and the mounting hole (7) is configured such that, in the radial cross-section, with the end (6a) of the reflective film as a reference, the central angle β is 45° or less.

[0017] The tenth aspect of the present invention is characterized in that, in the infrared heater of the ninth aspect, the mounting hole (7) is configured such that, in the radial cross-section, with reference to the end (6a) of the reflective film, the central angle β is 22.5° or less.

[0018] The eleventh aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the fluid supply port and the fluid outlet have a straight or L-shaped structure, and the installation positions of the fluid supply port and the fluid outlet have an angle of 0°, 90° or 180° in the radial cross-section of the inner tube and the outer tube.

[0019] The twelfth aspect of the present invention is characterized in that, in the infrared heater of the first aspect, the infrared heater includes: a tube (93) for covering the power supply section of the heating unit and the electrical wiring (92) connected to the power supply section; and a positive pressure generating device (94) connected to the tube for making the inside of the tube positive pressure.

[0020] The thirteenth aspect of the present invention is a fixing structure in which an infrared heater described in any one of the first to twelfth aspects is fixed to a furnace body. The fixing structure is characterized by having: a U-shaped component (97) having a heat-resistant elastic component on its surface; and a fixing component (99) that fixes the open end (98) of the U-shaped component to the furnace body (10). When the infrared heater is inserted into the U-shaped recess of the U-shaped component, the outer peripheral surface of the outer tube of the infrared heater is supported by the recess, and the U-shaped component is fixed to the furnace body by the fixing component.

[0021] The fourteenth aspect of the present invention is a drying oven comprising an infrared heater as described in any one of the first to twelfth aspects.

[0022] Invention Effects

[0023] In the infrared heater of this invention, since the inner tube and the outer tube are made of insulating inorganic material tubes that function as low-pass filters absorbing infrared rays with wavelengths greater than 6 μm, they can suppress the rise in furnace temperature and provide near-infrared rays with excellent ability to concentrate radiation on the workpiece and break the hydrogen bonds between molecules. Furthermore, the outer tube of the infrared heater of this invention detachably houses the heating unit. When housing the heating unit, the first flange of the inner tube abuts against the second flange of the outer tube, sealing the space for cooling fluid flow. Moreover, when replacing the heating unit, since the power supply for the heating unit is only located on the insertion port side of the outer tube, the heating unit can be easily pulled out of the outer tube, facilitating maintenance such as easy replacement of the heating unit. Attached Figure Description

[0024] Figure 1 This is an explanatory diagram of a drying oven according to an embodiment of the present invention.

[0025] Figure 2 This is a side view of the infrared heater used in the drying oven.

[0026] Figure 3 This is a side view of the heating unit of the infrared heater.

[0027] Figure 4 This is a side view of the outer tube of the infrared heater.

[0028] Figure 5 yes Figure 1 A-A' section view.

[0029] Figure 6 This is a side view of the outer tube of an infrared heater according to a variation of the present invention.

[0030] Figure 7This is a front view of the outer tube of an infrared heater according to other variations of the present invention.

[0031] Figure 8 This is an explanatory diagram of the fixing structure for fixing the infrared heater to the furnace body of the drying oven. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below. The present invention is not limited to the embodiments shown in the figures, and any design changes can be made as long as they do not depart from the technical scope described in the claims. Figure 1 This diagram illustrates the drying oven according to an embodiment of the present invention. 10 is the oven body of a coating drying oven for drying a coating film, inside which a thin-film workpiece W is continuously moved in one direction and continuously dried. A coating film having an electromagnetic absorption spectrum of less than 6 μm and hydrogen bonds is formed on the surface of the thin-film workpiece W. In this embodiment, the coating film is an electrode coating for lithium-ion batteries.

[0033] The electrodes of lithium-ion batteries are manufactured by coating a paste of active material powder (electrode material), used as the positive or negative electrode material, with a binder, conductive material, and solvent onto a metal sheet such as aluminum or copper, forming a coating film with a thickness of approximately 100 μm to 300 μm, and then drying it. The electrode material typically consists of lithium cobalt oxide as the positive electrode material, PVDF as the binder, carbon as the conductive material, and NMP as the solvent. In this embodiment, lithium cobalt oxide is used as the positive electrode material, but lithium nickel oxide or lithium manganese oxide can also be used. Additionally, graphite can be used as the negative electrode material. All of these are fine powders.

[0034] As described above, the binder is a component used to bond the electrode material to the carbon powder, which is a conductive material; in this embodiment, it is PVDF (polyvinylidene fluoride). In this embodiment, the solvent is NMP (N-methylpyrrolidone). However, the type of binder or solvent is not limited to this; various known substances can be used as constituent materials of the electrode coating for lithium-ion batteries.

[0035] In the coating drying oven 10 of this embodiment, the coating drying oven 10 is used to dry the coating film. Figure 1The first region 11 is designated as the initial state, the second region 12 as the intermediate state, and the third and fourth regions 13 as the final state, for drying the electrode coating for lithium-ion batteries. Infrared heaters 1 are arranged at appropriate intervals on the top surface of the furnace in the first region 11 and the second region 12. Furthermore, numerous hot air slits 18 for blowing hot air onto the electrode coating for lithium-ion batteries are arranged inside the furnace in the first region 11 and the second region 12. The hot air slits 18 on the top surface are configured to blow hot air between the infrared heaters 1. The hot air slits 19 on the lower surface blow hot air onto the lower surface of the electrode coating for lithium-ion batteries. Additionally, the temperature of the infrared heaters 1 and the hot air temperature in each region can be controlled individually.

[0036] The infrared heater 1 includes: a filament 2, which serves as a heating element that radiates infrared rays when heated; an inner tube 4, which houses the filament 2 and together with the filament 2 forms a heating unit 3; and an outer tube 5, which detachably houses the heating unit 3.

[0037] The inner tube 4 and outer tube 5 are insulating inorganic material tubes that function as low-pass filters absorbing infrared light with wavelengths above 6 μm. For example, known materials such as quartz glass or borosilicate crown glass can be used as the inner tube 4 and outer tube 5. Quartz glass tubes are preferred because they offer excellent heat resistance, thermal shock resistance, and cost-effectiveness. Since the quartz glass tube functions as a low-pass filter that efficiently absorbs infrared light with wavelengths above 4.7 μm, it can more effectively suppress the rise in furnace temperature and efficiently heat and dry the coating.

[0038] The outer tube 5 has: a first end 5a, provided with an insertion port 51 for inserting the heating unit 3 (see reference). Figure 8 The heating unit 3 has a third end 3a, located on the side opposite to the first end 5a, and equipped with a power supply section 91 for supplying power to the filament 2; and a fourth end 3b, located on the side opposite to the second end 5b, without the power supply section 91. Since the power supply section 91 is only installed on the third end 3a side, the heating unit 3 can be pulled out of the outer tube 5 without disconnecting the electrical wiring connected to the power supply section 91, making it easy to replace the heating unit 3. In order to form a structure in which the power supply section 91 is installed only on the third end 3a side, the infrared heater 1 is configured such that the interior of the inner tube 4 is divided into two regions by an insulator 31 such as quartz glass extending in the length direction of the inner tube 4, and in one region (in Figure 3 In the region above the insulator 31, after the filament 2 is passed from the third end 3a side to the fourth end 3b side, it is then passed through a hole provided in the insulator 31 to another region (in...). Figure 3In the middle, on the lower side of the insulator 31, the filament 2 is further made to pass from the fourth end 3b side to the third end 3a side.

[0039] The inner tube 4 has a first flange 41 disposed on the third end 3a side and has a diameter r2 larger than the outer diameter r1 of the inner tube 4. The insertion port 51 of the outer tube 5 has a second flange 52, which abuts against the first flange 41 when the heating unit 3 is housed inside the outer tube 5. The first flange 41 and the second flange 52 are fixed in the abutting state by a clip (not shown). When the heating unit 3 is housed inside the outer tube 5, a space 50 for cooling fluid to flow is formed between the inner tube 4 and the outer tube 5. The outer tube 5 has a fluid supply port 53 for supplying cooling fluid from the outside to the space 50 and a fluid discharge port 54 for discharging cooling fluid from the space 50 to the outside.

[0040] Furthermore, an O-ring is preferably provided, which is disposed between the first flange portion 41 of the inner tube 4 and the second flange portion 52 of the outer tube 5 to seal the insertion port 51. By distributing the O-ring between the first flange portion 41 and the second flange portion 52, the airtightness between the first flange portion 41 and the second flange portion 52 can be more reliably ensured.

[0041] Furthermore, the outer tube 5 has a cylindrical insertion hole 55 on the inner side of the second end 5b for inserting the fourth end 3b of the heating unit 3. The insertion hole 55 has an inner diameter r4 that is smaller than the inner diameter r3 of the second end 5b of the outer tube 5 and larger than the outer diameter r1 of the fourth end 3b of the heating unit 3. With this structure, the fourth end 3b of the heating unit 3 can be inserted into the insertion hole 55 of the outer tube 5, and the fourth end 3b of the heating unit 3 can be supported by the insertion hole 55. Therefore, the heating unit 3 can be more reliably positioned and fixed inside the outer tube 5.

[0042] Figure 5 yes Figure 2 A cross-sectional view along line A-A'. In Figure 5 The filament 2 and insulator 31 are omitted in the text. For example... Figure 5 As shown, the inner tube 4 includes a reflective film 6 for reflecting infrared rays irradiated from the filament 2 and thus limiting the direction of infrared irradiation. In this embodiment, an example is shown where the reflective film 6 is provided on the inner circumferential surface of the inner tube 4, but the reflective film can also be provided on the outer tube 5. The reflective film 6 can be a gold film or an aluminum film. By providing the reflective film 6, infrared rays can be more effectively irradiated toward the workpiece W. Furthermore, in a radial cross-sectional view of the inner tube 4 and the outer tube 5, the central angle α of the area where the reflective film 6 is provided is preferably 90° or more and 180° or less. If the central angle α of the area where the reflective film 6 is provided is less than 90°, too much infrared ray cannot be irradiated toward the workpiece W; if it exceeds 180°, cost-effectiveness decreases.

[0043] Furthermore, the infrared heater 1 has mounting holes 7 for installing thermocouples on the outer surface of the outer tube 5. By installing thermocouples on the outer surface of the outer tube 5, the surface temperature of the infrared heater can be accurately measured. Therefore, even in cases where flammable organic solvents evaporate from the workpiece W, control can be performed more reliably to prevent the surface of the infrared heater from reaching the ignition temperature of the organic solvent. Figure 5 As shown, the mounting hole 7 is preferably configured such that, in radial cross-sectional view, with the end 6a of the reflective film 6 as a reference, the central angle β is 45° or less, more preferably 22.5° or less. Furthermore, in Figure 5 The example shown is an example where the mounting hole 7 is located on the left side of the outer tube 5, but it can also be located on the right side. By limiting the position of the thermocouple mounting hole 7 to such a range, it is possible to prevent the thermocouple from being placed between the filament 2 and the workpiece W, thereby preventing the workpiece W from being placed in a position that would become the shadow of the thermocouple, and thus enabling more effective irradiation of infrared light onto the workpiece W.

[0044] In this embodiment, the fluid supply port 53 and the fluid discharge port 54 have an L-shaped structure, but as Figure 6 As shown, the fluid supply port 53 and the fluid outlet 54 can also be formed in a straight line according to the supply direction and discharge direction of the cooling fluid. Furthermore, in this embodiment, the installation positions of the fluid supply port 53 and the fluid outlet 54 are at an angle of 180° to each other in radial cross-sectional view. Figure 4 The installation position shown can be adjusted, but depending on the configuration of the cooling fluid flow path, it can also be formed at a 0° angle in radial cross-section. Figure 6 The installation position shown can also be formed at a 90° angle in radial cross-section. Figure 7 (Installation location shown).

[0045] Additionally, the infrared heater 1 includes: a tube 93 for covering the power supply section 91 of the heating unit 3 and the electrical wiring 92 connected to the power supply section 91; and a positive pressure generating device 94 connected to the tube 93 for creating a positive pressure inside the tube 93. By using the positive pressure generating device 94 to create a positive pressure in the space 50 of the infrared heater 1, it is possible to prevent volatile organic solvents from flowing into the space 50 and causing the volatile organic solvents to ignite.

[0046] Figure 8 This is an explanatory diagram of the fixing structure for fixing the infrared heater 1 to the furnace body 10 of the drying oven. Additionally, in Figure 8The diagram shows the state where the heating element 3 is pulled out of the outer tube 5. The fixing structure includes: a U-shaped member 97 with a heat-resistant elastic member on its surface; and a fixing member 99 that fixes the open end 98 of the U-shaped member 97 to the furnace body 10. With the infrared heater 1 inserted into the U-shaped recess of the U-shaped member 97, the outer circumferential surface of the outer tube 5 of the infrared heater 1 is supported by the recess, thereby fixing the U-shaped member 97 to the furnace body 10 using the fixing member 99. According to the infrared heater 1 of this embodiment, with the infrared heater 1 fixed to the furnace body 10 of the drying oven, the heating element 3 can be pulled out of the outer tube 5 for replacement, thus facilitating maintenance.

[0047] Next, the drying mechanism of the present invention will be explained. In a drying oven with a defined upper limit temperature due to the product's physical properties, it is practically not easy to control the short-wavelength (less than 6 μm) infrared radiation, which is considered effective for drying coatings, to dominate. The reasons for this are as follows: according to Planck's law of radiation, the temperature of the radiator, which is predominantly in this wavelength region, is at least 700°C. In a typical drying oven, the surface temperature of the heater, which is not allowed to come into contact with flammable volatile organic solvents, does not exceed 700°C. Even if it were allowed, the following problems can be deduced from the theory of radiation. First, the radiator at this high temperature does indeed preferentially radiate short-wavelength radiation; on the other hand, according to the Stefan-Boltzmann law, the radiant energy per unit area also becomes enormous. As a result, the temperature rise in various parts of the oven ultimately leads to the necessary increase, and in particular, from the perspective of energy efficiency and the heat resistance of the product when transport is stopped, a drying process for mass production purposes is impossible.

[0048] In contrast, in the infrared heater 1 of this invention, since the radiator is formed into a thin filament shape, the radiating area and heat capacity are both small. Considering each heater, this means it possesses the characteristics of a radiation source that "radiates a small amount of short-wavelength infrared radiation." That is, the temperature of the filament itself easily rises, and by changing the temperature of the filament, the number (spacing) of heaters can be further adjusted, thereby facilitating the control of the radiating area (total energy generation) per unit volume within the furnace. Furthermore, the temperature of the filament, energized at 700°C to 1200°C, drops instantly when energized, thus ensuring high safety during operation stoppages. By further incorporating a cooling mechanism in the inlet tube based on these features, the aforementioned problems are eliminated, enabling wavelength control of radiation within a drying oven for a wide range of applications.

[0049] The filament 2 is heated to 700–1200°C by an electric current, radiating infrared radiation with a peak wavelength around 3 μm. However, quartz glass or borosilicate crown glass functions as a low-pass filter, allowing infrared radiation with wavelengths less than 6 μm to pass through while absorbing infrared radiation with wavelengths greater than 6 μm. Therefore, the inner tube 4 and outer tube 5 selectively allow infrared radiation with wavelengths less than 6 μm from the electromagnetic waves radiated by the filament 2 to pass through and be supplied to the furnace. The infrared energy in this wavelength region is easily and directly absorbed by solvents such as NMP and converted into heat. In addition, it is consistent with the vibrational frequency of hydrogen bonds between solvent or water molecules, thus enabling efficient drying of electrode coatings for lithium-ion batteries.

[0050] However, the inner tube 4 and outer tube 5, in the long wavelength region above 6 μm, conversely become absorbers of radiation, heating themselves by absorbing infrared energy. The filament 2, at the aforementioned temperature, also radiates a considerable amount of infrared radiation in the long wavelength region above 6 μm; therefore, the tube temperature (the temperature of the junction with the flammable volatile organic solvent) may rise under this condition. Furthermore, as a result, the tube itself also becomes an infrared radiator, primarily radiating long wavelength infrared radiation above 6 μm secondary into the furnace. Compared to infrared radiation near 3 μm, this long wavelength infrared radiation is not only considered to contribute slightly less to the drying effect, but also causes the furnace fluid temperature to rise due to the wall temperature increase caused by the absorption of this infrared radiation in the furnace wall. In lithium-ion battery electrode coatings, this could potentially raise the temperature of various parts of the furnace above the solvent's ignition point.

[0051] Therefore, in this invention, with the heating unit 3 housed inside the outer tube 5, a space 50 for cooling fluid to flow is formed between the inner tube 4 and the outer tube 5. This allows the cooling fluid to flow through the space 50, converting the energy of long-wavelength infrared rays temporarily absorbed by the inner tube 4 and outer tube 5 into convective heat transfer energy, which is then removed from the system. As a result, the wavelength of the infrared rays ultimately supplied to the furnace is limited to the short-wavelength region. Even when the filament 2 is continuously heated at a high temperature, the outer tube 5, which is in direct contact with the volatile organic solvent, can be maintained at a safe temperature (below the ignition point of the solvent) of 200°C or less, more preferably 150°C or less, in the inner tube 4 and outer tube 5, particularly in the electrode coating for lithium-ion batteries. The cooling fluid is, for example, air or an inactive gas; however, in this embodiment, air is blown in from the fluid supply port 53 and heated air is removed from the fluid outlet 54.

[0052] The infrared heater 1 constructed in this way can selectively supply infrared rays with wavelengths less than 6 μm into the furnace, and the surface temperature of the infrared heater 1 is maintained at a low temperature, for example, below 200°C. Therefore, the furnace temperature can be kept below 200°C, more preferably below 150°C. Thus, there is no need to worry about solvent ignition or explosion. Furthermore, if the inner wall of the furnace body 10 is made of a reflective material with low infrared emissivity, the temperature rise of the furnace wall can be suppressed more effectively. For example, a glossy stainless steel sheet can be used as such a material.

[0053] Furthermore, since the electrode coating for solar power generation also has an electromagnetic wave absorption spectrum of less than 6 μm and contains hydrogen bonds, it can be dried using the coating drying oven of the present invention, just like the electrode coating for lithium-ion batteries described above.

[0054] Furthermore, in this invention, the type or flow rate of the fluid can be arbitrarily controlled. By increasing or decreasing the flow rate of the fluid, the surface temperature of the infrared heater 1 can be changed, and the radiation spectrum above 6 μm can be adjusted. This allows for the uniformity of the radiation wavelength of the infrared heater 1 and for achieving temperature equilibrium along the length of the furnace body. For example, in regions where it is necessary to actively break the hydrogen bonds between molecules, the infrared heater 1 can be cooled more intensely to radiate near-infrared radiation to the workpiece W, followed by gentle cooling to raise the overall temperature of the workpiece.

[0055] In the infrared heater 1 of this embodiment, since the inner tube 4 and the outer tube 5 are made of insulating inorganic material tubes that function as low-pass filters for absorbing infrared rays with wavelengths of 6 μm and above, they can suppress the rise in furnace temperature and provide near-infrared rays with excellent ability to concentrate radiation on the workpiece and break the hydrogen bonds between molecules. In addition, the outer tube 5 of the infrared heater 1 houses the heating unit 3 in a way that allows it to be easily installed and removed. However, when housing the heating unit 3, the first flange 41 of the inner tube 4 abuts against the second flange 52 of the outer tube 5 to seal the space 50 for the flow of cooling fluid. Furthermore, when replacing the heating unit 3, since the power supply part 91 of the heating unit 3 is only provided on the insertion port 51 side of the outer tube 5, the heating unit 3 can be easily pulled out of the outer tube 5, making maintenance easy, such as easy replacement of the heating unit 3.

[0056] Symbol Explanation

[0057] 1. Infrared heater

[0058] 2. Filament (heating element)

[0059] 3 Heating Units

[0060] 3a Third end

[0061] 3b Fourth end

[0062] 4 Inner tube

[0063] 5. Outer tube

[0064] 5a First end

[0065] 5b Second end

[0066] 6. Reflective film

[0067] 6a End of the reflective film

[0068] 7 mounting holes

[0069] 10 Furnace body

[0070] 41 First flange portion

[0071] 50 Space for cooling fluid flow

[0072] 51 Insertion Port

[0073] 52 Second flange portion

[0074] 53 Fluid supply port

[0075] 54 Fluid discharge outlet

[0076] 55 Insertion Hole

[0077] 91 Power Supply Department

[0078] 92 Electrical wiring

[0079] 93 tubes

[0080] 94 Positive pressure generating device

[0081] 97 U-shaped components

[0082] 98 Open end of U-shaped component

[0083] 99. Fixed components.

Claims

1. An infrared heater (1) comprising: a heat generating body (2) that radiates infrared rays when heated; an inner tube (4) that houses the heat generating body inside and constitutes a heat generating unit (3) together with the heat generating body; and an outer tube (5) that houses the heat generating unit inside detachably, the infrared heater being characterized in that: the inner tube and / or the outer tube is an insulating inorganic material tube that functions as a low-pass filter that absorbs infrared rays of a wavelength of 6 μm or more, the outer tube has a first end portion (5a) provided with an insertion port (51) into which the heat generating unit is inserted, and a second end portion (5b) located on the side opposite to the first end portion, the heat generating unit has a third end portion (3a) disposed on the first end portion side and provided with a power supply portion (91) for supplying power to the heat generating body, and a fourth end portion (3b) disposed on the second end portion side and not provided with a power supply portion, the inner tube has a first flange portion (41) disposed on the third end portion side and having a diameter (r2) larger than an outer diameter (rl) of the inner tube, the insertion port of the outer tube has a second flange portion (52) that abuts against the first flange portion in a state where the heat generating unit is housed inside the outer tube, and in the state where the heat generating unit is housed inside the outer tube, a space (50) for allowing a cooling fluid to flow is formed between the inner tube and the outer tube, and the outer tube is provided with a fluid supply port (53) for supplying the cooling fluid from the outside to the space and a fluid discharge port (54) for discharging the cooling fluid from the space to the outside.

2. The infrared heater according to claim 1, characterized in that: the inner tube and / or the outer tube is an insulating inorganic material tube that functions as a low-pass filter that absorbs infrared rays of a wavelength of 4.7 μm or more.

3. The infrared heater according to claim 1, characterized in that: the outer tube is provided with a cylindrical insertion hole (55) into which the fourth end portion of the heat generating unit is inserted on the inside of the second end portion, and the insertion hole has an inner diameter (r4) smaller than an inner diameter (r3) of the second end portion of the outer tube and larger than an outer diameter of the fourth end portion of the heat generating unit.

4. The infrared heater according to claim 1, characterized in that: the infrared heater further comprises an O-ring disposed between the first flange portion of the inner tube and the second flange portion of the outer tube for sealing the insertion port.

5. The infrared heater according to claim 1, characterized in that: the inner tube and / or the outer tube is provided with a reflection film (6) for reflecting infrared rays radiated from the heat generating body to restrict the direction of radiation of the infrared rays.

6. The infrared heater according to claim 5, characterized in that: in a radial cross section of the inner tube and the outer tube, a central angle α of a range in which the reflection film is provided is 90° or more and 180° or less.

7. The infrared heater according to claim 5, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The inner tube and the outer tube are quartz tubes, The reflecting film is a gold film or an aluminum film.

8. The infrared heater according to claim 1, wherein An installation hole (7) for installing a thermocouple is provided on an outer surface of the outer tube.

9. The infrared heater according to claim 8, wherein The inner tube and the outer tube are configured in a concentric circular shape in a radial cross section, The inner tube and / or the outer tube is provided with a reflecting film (6) for reflecting infrared rays radiated from the heat generating unit to limit the radiating direction of the infrared rays, The installation hole (7) is provided so that a central angle β is 45° or less with respect to an end portion (6a) of the reflecting film in the radial cross section.

10. The infrared heater according to claim 9, wherein The installation hole (7) is provided so that a central angle β is 22.5° or less with respect to an end portion (6a) of the reflecting film in the radial cross section.

11. The infrared heater according to claim 1, wherein The fluid supply port and the fluid discharge port have a linear or L-shaped configuration, and the installation positions of the fluid supply port and the fluid discharge port have an angle of 0°, 90°, or 180° in a radial cross section of the inner tube and the outer tube.

12. The infrared heater according to claim 1, wherein The infrared heater is provided with a tube (93) for covering the power supply portion of the heat generating unit and an electric wiring (92) connected to the power supply portion, and a positive pressure generating device (94) connected to the tube for making the inside of the tube a positive pressure.

13. A fixing structure for fixing the infrared heater according to any one of claims 1 to 12 to a furnace body, The fixing structure is characterized in that a U-shaped member (97) having a heat resistant elastic member on a surface, and a fixing member (99) for fixing an open end (98) of the U-shaped member to a furnace body (10), the outer peripheral surface of the outer tube of the infrared heater is supported by a U-shaped recess of the U-shaped member in a state where the infrared heater is inserted into the U-shaped recess, and the U-shaped member is fixed to the furnace body by the fixing member.

14. A drying oven, characterized by The infrared heater according to any one of claims 1 to 12 is provided.

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