JPH0140253B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric heater that performs heating using radiant heat using a surface heating element.

Conventionally, devices that perform heating by radiating radiant heat toward the human body have a structure in which a surface heating element is baked on the back side of a ceramic plate. However, since ceramic has low mechanical strength, the plate thickness should be reduced to 5.
mm, and since ceramic has low thermal conductivity, the thermal resistance between the back and front surfaces of the ceramic plate becomes large. For this reason, the heat given from the surface heating element is difficult to transfer to the front surface of the ceramic plate and tends to escape to the back side, resulting in a low radiation efficiency.Also, since ceramic has a large heat capacity, electricity is applied to the surface heating element. However, the temperature rise at the front surface of the ceramic plate is slow, and the generation of radiant heat is considerably delayed from the start of energization to the surface heating element, resulting in a disadvantage that the heating properties are poor.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an electric heater that not only ensures insulation of the surface heating element but also has high radiation efficiency and is excellent in quick heating properties.

An embodiment of the present invention will be described below with reference to FIG. 1 is a thin steel plate as a metal plate,
The entire surface of this is coated with a thin coating material made of e.g. enamel to form an insulating film 2. 3 is a surface heating element baked on a coating 2 formed on one side of the thin steel plate 1. This is mainly composed of carbon, and is set to generate heat in the temperature range described later. The electrodes 4, 4 are baked, and the flat heating body 5 is constructed with the above structure. Reference numeral 6 denotes a flat container-shaped case with an opening 7 formed on the front surface, and the above-mentioned flat heating body 5 is attached to the inner edge of the opening 7 through a cushion material 8 with the other side facing forward. A heat insulating material 9 is installed in the case 6 in advance so as to leave a predetermined gap with respect to the rear surface of the flat heating body 5.

Therefore, the enamel used as the coating material is originally a good electrical insulator, and the coating material 2
can be easily formed to be very thin, with a thickness of several tens to several hundred microns, and the thin coating 2 has sufficient dielectric strength. In addition, although enamel itself has relatively low thermal conductivity, the coating 2 made of enamel on the front and rear surfaces of the thin steel plate 1 is very thin and has extremely low thermal resistance, and the thin steel plate 1 has good thermal conductivity and small heat capacity. When the surface heating element 3 is energized and generates heat, the heat is efficiently transferred to the coating 2 on the front side of the flat heating element 5 in an extremely short time, and the heat is prevented from escaping to the rear side of the surface heating element 3 as much as possible. Prevented.

In addition, enamel has a high spectral emissivity in the infrared region with a wavelength of 4.5 to 8μ, and therefore Wien's displacement law λmax × T = 2897.8 (μ〓) λmax: Wavelength T: 70℃ depending on the absolute temperature It has the property of efficiently generating radiant heat when the surface temperature is between 370°C and 370°C. Therefore, the heat generation temperature of the above-mentioned surface heating element 3 is set to 70
If the temperature is set within the temperature range of 370° C. to meet the purpose of use, the efficiency of generating radiant heat relative to the power consumed by the surface heating element 3 can be made high.

The radiant heat in the infrared region, where enamel has a high spectral emissivity, matches the wavelength region in which the human body can best absorb heat, and the coating 2 made of enamel is very suitable for heating the human body.

FIG. 2 shows another embodiment of the present invention, and only the parts different from FIG. 1 will be explained.
That is, the surface heating element 3 is coated in advance with a coating material made of e.g. enamel to a predetermined thickness of, e.g., about 0.3 mm, separately from the thin steel plate 1, and an insulating film 10 is formed on the surface thereof.
Coating 2 formed on one side of thin steel plate 1 and surface heating element 3
The case 11 has a rectangular frame shape with a heat insulating material 9 in contact with the rear side of the surface heating element 3.
The planar heating element 3 is held in place by the thin steel plate 1.
Since it is coated with the coating 10 separately from the coating 10, the insulation of the surface heating element 3 can be further improved, and even if pinholes are formed in the coatings 2 and 10, they will not coincide with each other. In comparison, the reliability of the insulation can be improved, the insulation space between the surface heating element 3 and the heat insulating material 9 can be made unnecessary, the whole can be made thinner, and the reinforcing effect of the coating 10 can be obtained. Deformation of the surface heating element 3 is prevented, and the strength is also increased compared to the one shown in FIG.

Note that since the coating 10 only needs to have insulation properties, various coating materials other than enamel can be used.

The present invention forms a coating made of enamel having a high spectral emissivity in the infrared region on the front and rear surfaces of a metal plate, and places a surface heating element in close contact with the coating formed on the rear surface of the metal plate. Since the heat generation temperature of the body is made to match the wavelength range where the spectral emissivity of the coating is high, it is thin enough and has superior strength compared to conventional ones, and has a smaller heat capacity, resulting in surface heat generation. It is possible to provide an electric heater that not only ensures body insulation but also has high radiation efficiency and is also excellent in instant heating.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the invention. In the drawing, 1 is a thin steel plate (metal plate), 2 is a coating, and 3
5 is a flat heating element, 6 is a case, 9 is a heat insulating material, 10 is a coating, and 11 is a case.

Claims (1)

[Scope of Claims] 1. A coating made of enamel having high spectral emissivity in the infrared region is formed on the front and rear surfaces of a metal plate, and a surface heating element is closely attached to the coating formed on the rear surface of the metal plate, An electric heater characterized in that the heat generation temperature of the surface heating element is made to match a wavelength range in which the spectral emissivity of the coating is high. 2. The heating element is coated with an insulating coating material, and the coating layer and the coating formed on the rear surface of the metal plate are welded to each other and provided in close contact with the coating. The electric heater according to claim 1, characterized in that: