JP2000077165A - Radiation-type heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating element of high far-infrared emissivity for household cooking apparatuses, heating apparatuses, printers, and the like, by inserting, into a transparent tube, a thermal radiator and a heating element that generates Joule's heat, and utilizing the heat emitted from the thermal radiator and from the heating element at the same time. SOLUTION: A thermal radiator 4 and a heating element 5 that generates Joule's heat are inserted into a transparent tube 1. The thermal radiator 4 is heated by receiving Joule's heat generated by the heating element 5 powered from external lead wires 2 and emits thermal radiation including far infrared rays. Therefore, both of the thermal radiation from the heating element 5 and the thermal radiation including far infrared rays generated by the thermal radiator 4 are emitted from the transparent tube 1. Carbon, boron carbide, aluminum nitride, or the like is used for the thermal radiator 4, and heat resistant glass, such as quartz glass, is used for the transparent tube 1. The transparent tube 1 is filled with argon gas, nitrogen gas, etc., therefore the heating element 5 is prevented from breaking due to oxidation by the air. Tungsten wire is used as the heating element 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation heating element using a heat radiation element.

[0002]

2. Description of the Related Art It is desirable that a heating element used in home cooking appliances and heaters has a large far-infrared emissivity such as "charcoal fire". "Charcoal fire" has the highest far-infrared emissivity of all materials,
It is considered to be the best heat source for dishes such as grilled fish.
However, oxidative consumption in the air is the biggest difficulty.

[0003] Conventionally used heating elements include a metal radiating heating element configured to also use a heating wire, which is a heating wire, as a heat radiating element, and a non-metallic heating element using a non-metal heating element. There is a non-metallic radiant heating element that is also used as a thermal radiator. Typical examples of the heating wire include a nickel-chromium alloy wire called a nichrome wire and an iron-chromium alloy wire called a kanthal wire, but the maximum operating temperature is 1200 ° C. . Tungsten can be used up to 2500 ° C. in a vacuum or in a hydrogen stream. As a typical non-metallic heating wire, silicon carbide is used. Silicon carbide has a maximum use temperature of 1350 ° C.

[0004] The average emissivity of the tungsten wire for far-infrared rays is as low as 30 to 39%, and a heating performance superior to "charcoal fire" has not been obtained. Further, the emissivity of far-infrared rays is low even for a nickel-chromium alloy wire called a nichrome wire and an iron-chromium alloy wire called a kanthal wire. In order to compensate for the low emissivity of far-infrared rays, there is a method of applying a black paint or the like to a bulb having a built-in heating element. However, the black paint applied in this way suffers cracks due to repeated heating and cooling, or peels off, or oils and salts scattered from cooked foods accumulate on the surface of the paint, causing the emissivity of far infrared rays to decrease. It is going to drop. In addition, since the metal wire resistance radiation heating element originally has a small specific resistance, it is usual to perform coiling in order to obtain a resistance value corresponding to a determined heating length. Therefore,
The metal wire resistance radiant heating element also has a disadvantage that the temperature distribution in the longitudinal direction of the heater becomes non-uniform because the coil expands and bends at the time of heat generation. In addition, since the resistance of the metal wire resistance radiation heating element is generally lower at a lower temperature, an inrush current is generated at the same time as energization, and in some cases, may cause disconnection.

[0005] The inventors of the present invention have proposed carbon which has excellent heat resistance, thermal shock resistance and corrosion resistance, has the highest emissivity in the far infrared region among all materials, and has a very high melting point of 3800 ° C. Japanese Patent Application No. Hei 10-1
No. 60110.

[0006]

As described above, since the metal wire resistance radiating heating element is coiled, the coil expands and bends when heat is generated. For this reason, there is a problem that the temperature distribution in the longitudinal direction of the heater becomes non-uniform, or the heater is disconnected due to an inrush current when energized. On the other hand, carbon has a specific resistance of 1000 to 500 at room temperature.
Since it is very small at about 0 μΩ · cm, it has a problem that it cannot be used as a radiation heating element unless the wire diameter is extremely increased and the current value is increased.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a structure in which a heat radiator having a high emissivity of far infrared rays is heated by Joule heat from a metal resistance heating element. Is what it is.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a heat radiator and a heating element that generates Joule heat are inserted into a transparent tube, and radiant heat generated from the heat radiator and the heating element is simultaneously emitted. Emission suitable for home cooking appliances and heaters with high far-infrared emissivity, and for heating devices for fixing units such as infrared therapy units for home use and printers for electronic copiers, as well as electric insulation and heat equipment. It is a type heating element.

According to a second aspect of the present invention, there are provided a plurality of heat radiators, which are used for home cooking appliances, heaters, and home infrared radiation having a high far-infrared emissivity while consuming a specified amount of power. It is a heating element for heating a fixing device such as a treatment device or a printer of an electronic copying machine, or a radiation heating element suitable for electric insulation and heat equipment.

[0010] The invention according to claim 3 uses a heat-resistant glass as the transparent tube, and can be operated in a high-temperature region near the softening point of the glass, for a home-use cooking appliance, a heater, or a home-use infrared therapy device. And a heating element for heating a fixing device such as a printer of an electronic copier or a radiation heating element suitable for electric insulation and heat equipment.

According to a fourth aspect of the present invention, the transparent tube has a single gas of argon or nitrogen or a mixed gas of argon and nitrogen, and the heating element and the heat radiating element are formed by air oxidation. It can prevent disconnection and wear, and has a large emissivity of far-infrared rays.It can be used for heating equipment for home cooking appliances and heaters, as well as heating devices for fixing units such as infrared therapy units for home use and printers for electronic copiers. It is a radiant heating element suitable for electric insulation and heat equipment.

According to a fifth aspect of the present invention, the heating element is formed by winding a heating wire, and the heat radiating element is disposed inside the wound heating element, so that the heating element is indirectly heated by the heating element. The radiant heat radiated from the heat radiator and the heating element can be used simultaneously, and it can be used for home cooking appliances, heaters, home infrared therapy units, printers for electronic copiers, etc. The heating element is a heating element for heating the fixing device and a radiation heating element suitable for electric insulation and heat equipment.

According to a sixth aspect of the present invention, the heating element is formed by winding a heating wire, and the heat radiating element is arranged outside the wound heating element, and is indirectly connected to the resistance radiating type heating element. The radiant heat radiated from the heat radiator and the heater can be used at the same time, and it has a large far-infrared emissivity for home cooking appliances, heaters, home infrared therapy units and electronic copiers. The heating element is a heating element for heating a fixing device such as a printer, or a radiation heating element suitable for electric insulation and heat equipment.

According to a seventh aspect of the present invention, the use of carbon, boron carbide, silicon carbide, aluminum nitride, silicon nitride, or boron nitride as a heat radiator makes it possible to produce household cooking with a high emissivity of far infrared rays. It is a heating element for heating a fixing device, such as an infrared therapy device for a device, a heater, or a home, or a printer of an electronic copier, or a radiation heating element suitable for electric insulation and heat equipment.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. A heat radiator 4 and a heat generator 5 that generates Joule heat are inserted into the transparent tube 1. The heat radiator 4 receives the Joule heat generated by the heat generator 5 when the heat generator 5 is energized from the external lead wire 2 and is heated to emit heat radiation including far infrared rays. Therefore, from the transparent tube 1, both thermal radiation generated by the heating element 5 itself and thermal radiation including far-infrared rays generated by the thermal radiator 4 are generated.

In this embodiment, as the heat radiator 4, carbon, boron carbide, silicon carbide, aluminum nitride, silicon nitride, or boron nitride is used. Further, in FIG. 1, the number of the heat radiators 4 is one, but a configuration using a plurality of heat radiators may be employed.

In this embodiment, heat-resistant glass such as quartz glass is used as the transparent tube 1. Therefore, for example, when quartz glass is used, it can be used in a high temperature region near 1650 ° C., which is the softening point of quartz glass. In other words, the setting of the surface temperature due to the heat generated by the heating element 5 can be set to be close to 1650 ° C., and it can be used as a highly efficient heating element. In this embodiment, quartz glass is used as the transparent tube 1. However, as long as the tube has high heat resistance and is transparent, there is no particular limitation to quartz glass.

In this embodiment, the transparent tube 1 is filled with a single gas of argon or nitrogen or a mixed gas of argon and nitrogen. For this reason, the heating element 5 brought into a high temperature state by Joule heat generated by energization is
It is possible to prevent disconnection due to air oxidation.

In this embodiment, a tungsten wire is used as the heating element 5. That is, tungsten has a low vapor pressure (4507 ° C. is necessary to exhibit a vapor pressure of 10 mmHg) and a very high melting point of about 3400 ° C. Tungsten wires have already been put to practical use in halogen lamps and the like.

In this embodiment, the heating element 5 is formed by winding a heating wire of a tungsten wire in a coil shape, and the heat radiating element 4 is disposed inside the wound heating element 5. Things. At this time, there is no particular problem even if the heat radiator 4 is arranged outside the wound heat generator 5.

The operation of this embodiment will be described below. A black body completely absorbs all radiant energy incident from the outside, and the radiant energy radiated from the black body is the maximum value of the radiant energy at a given temperature over the entire wavelength range. Things.

The carbon used as the thermal radiator 4 in this embodiment is the best material for a radiant heating element because it gives black body radiation approximately. That is, it is optimal as a heating element for a heating cooking appliance or a heating appliance using radiation. Also, although the emissivity in the far infrared region is somewhat inferior to carbon, boron carbide, silicon carbide, aluminum nitride, silicon nitride, and boron nitride are also the best materials as heating elements.

When a switch (not shown) is turned on and a commercial AC power is supplied to the heating element 5 from the external lead wire 2, the heating element 5 generates Joule heat and radiates infrared rays to the outside via the transparent tube 1. I do. At the same time, the heat radiator 4 housed in the transparent tube 1 is heated. Therefore, both the infrared rays generated by the heating element 5 and the infrared rays generated by the heat radiating element 4 are emitted from the transparent tube 1.

FIG. 2 shows the characteristics of the wavelength of the infrared ray radiated from the transparent tube 1 to the outside and the intensity of the infrared ray. Note that the vertical axis of FIG. 2 shows the radiation intensity when the radiation intensity of a perfect black body is set to 100.
The characteristic shown in FIG. 2A is that of the present embodiment.
That is, carbon or boron carbide, silicon carbide, aluminum nitride, silicon nitride, or boron nitride is used as the heat radiator 4 and tungsten is used as the heat generator 5. What is indicated by b is the one described in the conventional example. That is, only tungsten is used as the heating element. At this time, the configuration of the conventional example and the configuration of the present embodiment are both set so that the power consumption is 400 W. As can be easily understood from FIG. 2, the infrared radiation characteristic of the present embodiment is much better than that of the conventional constitution in the wavelength of 2.0 μm or more, that is, in the far infrared region.

Hereinafter, a method of manufacturing the sample used in the above experiment will be described. First, the outer diameter is 1-4 mm and the length is 2
An 80 mm heat radiator 4 is prepared. Next, a quartz pipe having an inner diameter of 8 mm and an outer diameter of 10 mm is prepared as the transparent tube 1. Generally, quartz glass has high heat resistance and softens only at 1650 ° C. Next, one or more heat radiators 4 are inserted into the transparent tube 1. Heat radiator 4 includes
An insulator tube 6 having a length of 5 to 10 mm is inserted at a key position. After the pressure is reduced to 0.01 Torr or less using a vacuum pump such as a rotary pump, an inert gas which is a simple gas of argon or nitrogen or a mixed gas of argon and nitrogen is sealed. The purpose of filling the inert gas is to prevent the heat radiator 4 from being oxidized and consumed at the time of heat generation,
That is, the heating element 5 is not disconnected by oxidation. At this time, a simple nitrogen gas or a mixed gas of argon and nitrogen is more effective than argon in order to prevent arc discharge when a small amount of water vapor remains inside or when the degree of vacuum is low.
Also in this case, the gas pressure is appropriately around 600 Torr.

Thus, both ends of the transparent tube 1 are sealed. This sealing is performed using a connection port between the heating element 5 and the external lead wire 2. That is, the extension of the coil forming the heating element 5 is connected to the molybdenum foil 3 via the platinum foil. The external lead wire 2 is connected to the molybdenum foil 3 in advance. Tungsten and molybdenum cannot be welded as they are, but they can be easily welded because the respective intermetallic compounds are formed by inserting a platinum foil. The sealing portion is a portion of the molybdenum foil 3. In particular, the sealing portion is made of a carbon radiator 4.
When it is used, it is extremely important as a sealing technique for sealing the inside and the outside. In the present embodiment, H. The seal is completely sealed by using molybdenum foil manufactured by CROSS. The cross-sectional shape of the molybdenum foil is a convex lens shape, the film thickness at the center is about 30 μm, the tip side is a feather edge, and there is only a gap of a maximum of several angstroms (1 angstroms = 0.1 nm). At the time of heat generation, molybdenum relatively expands more than quartz glass, so that air does not enter or inert gas inside escapes. Actually, both ends of the transparent tube 1 are softened by heating with a burner, and the molybdenum foil 3 is closed in the sealing portion at the same time as the transparent tube 1 is sealed by applying pressure from the surroundings.

As described above, according to the experiments performed by the inventors, it was found that the heat radiation was a uniform round rod carbon rod having a heating length of 280 mm and a wire diameter of 1.2 mm having a specific resistance of 1000 to 2000 μΩ · cm. Body 4 and heating element 5 using tungsten
Was used to obtain a 100 V-400 W radiation heating element.

In the radiant heating element of this embodiment, 167 W is required to increase the temperature of a place 10 cm away from the room by 35 ° C. compared to room temperature. In the case of a quartz tube heater used as a heating element, 186 W is required. That is, when the radiation heating element of the present embodiment is used, power consumption can be reduced by about 10%.

When the radiation type heating element of the present embodiment is used in a microwave oven, the microwave is supplied to the microwave oven by providing the coiling portion of the heating element 5 at the exit of the cooking chamber of the microwave oven. This prevents leakage from the housing to the outside.

[0030]

According to the first aspect of the present invention, the heat radiator and the heating element that generates Joule heat are inserted into a transparent tube, and the radiant heat generated from the heat radiator and the heating element is reduced. It can be used at the same time and has high far-infrared emissivity. It is suitable for heating equipment for home cooking appliances and heaters, as well as for heating devices for fixing units such as infrared therapy units and printers for electronic copiers, as well as for electric insulation and heating equipment This realizes a radiation heating element.

According to a second aspect of the present invention, there is provided a configuration in which a plurality of heat radiators are used. The present invention realizes a heating element for heating a fixing device such as an infrared therapy device for use in a printer or a printer of an electronic copying machine, and a radiation heating element suitable for electric insulation and heat equipment.

According to a third aspect of the present invention, the transparent tube is made of heat-resistant glass, and can be operated in a high-temperature region near the softening point of the glass for home cooking appliances, heaters, home infrared treatment devices, and the like. The present invention realizes a heating element for heating a fixing device such as a printer of an electronic copier and a radiation heating element suitable for electric insulation and heat equipment.

According to a fourth aspect of the present invention, the transparent tube has a structure in which a single gas of argon or nitrogen or a mixed gas of argon and nitrogen is enclosed, and the heating element and the heat radiating element are disconnected by air oxidation. Heating elements and heaters for fixing equipment such as home cooking appliances and heaters with high emissivity of far-infrared rays, household infrared therapy devices, and printers for electronic copiers that can prevent dripping and consumption. It is intended to realize a radiation heating element suitable for heat retention and heat equipment.

According to a fifth aspect of the present invention, the heating element is configured by winding a heating wire, and the heat radiating element is disposed inside the wound heating element, so that the heating element is indirectly heated by the heating element. The radiant heat radiated from the heat radiator and the heating element can be used at the same time, and it is used for home cooking appliances and heaters with a large far-infrared emissivity, as well as home infrared therapy equipment and printers for electronic copiers. It is intended to realize a radiation heating element suitable for a heater for heating a heater and an electric insulation and heating device.

According to a sixth aspect of the present invention, the heating element is formed by winding a heating wire, and the heat radiating element is disposed outside the wound heating element, so that the heating element is indirectly heated by the heating element. The radiant heat radiated from the heat radiator and the heating element can be used at the same time, and it is used for home cooking appliances and heaters with a large far-infrared emissivity, as well as home infrared therapy equipment and printers for electronic copiers. It is intended to realize a radiation heating element suitable for a heater for heating a heater and an electric insulation and heating device.

[0036] The invention described in claim 7 is an infrared treatment for home use having a high far-infrared emissivity by using carbon, boron carbide, silicon carbide, aluminum nitride, silicon nitride, or boron nitride as the heat radiator. The present invention realizes a heating element for heating a fixing device such as a copying machine or a printer of an electronic copying machine, and a radiation heating element suitable for electric insulation and heat equipment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a radiation heating element according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an infrared radiation characteristic of the radiation heating element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent tube 2 External lead wire 3 Molybdenum foil 4 Heat radiator 5 Heating element 6 Insulator tube

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kunikazu Kuchino 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Company F term (reference) 3K092 PP01 PP03 PP06 PP18 PP20 QA02 QB02 QB27 QC16 QC37 RA03 RB14 RD10 RD11 SS34 SS40 TT01 TT36 VV03 VV09 VV28

Claims (7)

[Claims] 1. A radiant heating element in which a heat radiator and a heating element that generates Joule heat are inserted into a transparent tube. 2. The radiation heating element according to claim 1, wherein the number of the heat radiation elements is plural. 3. The radiation heating element according to claim 1, wherein the transparent tube is made of heat-resistant glass. 4. The radiation type heating element according to claim 1, wherein the transparent tube has a single gas of argon or nitrogen or a mixed gas of argon and nitrogen enclosed therein. 5. The radiation heating element according to claim 1, wherein the heating element is formed by winding a heating wire, and the heat radiator is disposed inside the wound heating element. 6. The radiation heating element according to claim 1, wherein the heating element is formed by winding a heating wire, and the heat radiator is disposed outside the wound heating element. 7. The radiation heating element according to claim 1, wherein carbon, boron carbide, silicon carbide, aluminum nitride, silicon nitride, or boron nitride is used as the heat radiation element.