JPH09213461A - Ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater hardly lowering heating efficiency even if used for a long time and with high reliability by covering the surface of a heat generating part with glass. SOLUTION: A ceramic heater 1 is formed by burying a resistance heat generating element 12 in a base body 11 made from ceramics, and the surface of a heat generating part 13 is covered with glass 2. The surface roughness of the glass 2 is preferable to be Rz (JIS) 1.6 or less. It is freferable that the base body made of ceramic is shaped like a pipe or a plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater for use in a bath for 24 hours, a toilet seat for heating, a kettle for boiling water, etc., and a direct type ceramic heater which is directly immersed in water for heating.

[0002]

2. Description of the Related Art Conventionally, the surface of a ceramic substrate of a ceramic heater, which is directly immersed to heat a liquid such as water, has not been treated in particular, although it has been polished after the step of firing the ceramic. .

[0003]

However, the surface of ceramics is rough in the as-fired state due to pinholes and the like when viewed microscopically. Therefore, when the ceramics heater is directly immersed in water to heat the water, the components in the water (foreign substances such as CaO (calcia)) invade the microscopic irregularities on the surface by the wedge effect and adhere and accumulate. It will be easier. In particular, the surface of the heat generating portion where the temperature of the ceramics heater is high is active, so that it is easy to adhere and deposit. When CaO or the like adheres and accumulates, a porous portion is generated by the calcia and the like accumulated between the ceramics heater and the water, and the heating efficiency for heating the water decreases. A problem to be solved by the present invention is to provide a highly reliable ceramic heater that does not easily deteriorate in heating efficiency even after long-term use.

[0004]

Means and Actions for Solving the Problem The means is a ceramics heater in which a resistance heating element is embedded in a base made of ceramics, and the surface of the heating portion is covered with glass. By coating the surface of the ceramic heater with glass,
Since its surface can be made smooth, foreign matter (CaO
(Calcia) etc. does not easily adhere to or accumulate on the surface. Here, the "heat generating portion" of the ceramics heater means the surface of the base body made of ceramics corresponding to the portion in which the resistance heating element is embedded. The "surface of the heat generating part" is
This is because the heat-generating part is particularly active and is likely to adhere and accumulate. Therefore, it is preferable to cover at least the surface of the heat generating portion with glass. The ceramic substrate of the ceramic heater is preferably pipe-shaped. This is because it is easy to uniformly heat a liquid such as water by forming the ceramics heater into a pipe shape. The ceramic substrate of the ceramic heater preferably has a plate shape.
The surface roughness of the glass of the ceramic heater is RZ
(JIS standard) It is preferably 1.6 or less. This is because when the surface roughness exceeds RZ 1.6, foreign matter (CaO (calcia) etc.) in water is likely to adhere and deposit on the surface.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a ceramics heater unit incorporating the ceramics heater 1 of the present invention. FIG. 2 is a sectional view taken along the line CC of FIG. The ceramic heater 1 of the present invention has, for example, a pipe shape as shown in FIG. 1, and is fixed to a ceramic heater unit outer frame 3 with packing 4. Specifically, the water guided by the guide passage 5 is warmed while flowing from the inlet A through the inside of the pipe and on the outer peripheral side of the ceramic heater 1 and flows out from the outlet B. The ceramic heater 1 of the present invention is a ceramic heater in which a resistance heating element 12 is embedded in a base made of ceramics, and at least the surface of a heating portion 13 is covered with glass 2. The ceramic heater of the present invention has, for example, a plate shape shown in FIG. 3 as another shape.

-Manufacturing- Pipe-shaped ceramics heater Sintered pipe-shaped ceramics is prepared. Then, a metallized-printed green sheet to be the resistance heating element and the electrode wiring is prepared, and the metallized-printed green sheet is wound around the pipe-shaped ceramic and sintered. Next, the ceramic heater 1 of the present invention can be obtained by applying glass of a predetermined composition to at least the "heat generating portion" and firing it. Plate-shaped ceramics heater Prepare a metallized printed green sheet to be a resistance heating element and electrode wiring, and sinter another green sheet on the metallized printed surface. Then, at least the "heat generating part" is coated with glass having a predetermined composition and fired to obtain the ceramic heater 1'of the present invention. The ceramic material forming the base 11 of the ceramic heater 1 is, for example, alumina, zirconia, silicon nitride, aluminum nitride or the like. Also,
As a material forming the glass 2, for example, SiO ₂ ,
A material composed of CaO, Al ₂ O ₃ , Na ₂ 0, K ₂₀ and PbO is preferable. The material forming the resistance heating element 12 is, for example, tungsten, molybdenum, manganese, or the like.

-Experimental Example- An experiment was conducted with the ceramic heater unit shown in FIG. The ceramics heater 1 was made of ceramics 11 containing alumina as a main component, and W (tungsten) was used as the resistance heating element 12. The glass shown in Table 1 was coated. When the inflow temperature from A was about 40 ° C and the outflow temperature of B was about 42 ° C, the deposited thickness of CaO and the like was measured. As a comparative example, a ceramic heater not coated with glass was also measured in the same manner. As can be seen from the experimental results, the ceramic heater 1 of the present invention is unlikely to deposit CaO and the like even after being used for a long time.

[0008]

According to the present invention, the surface of the heating portion of the ceramics heater can be made smooth. Therefore, the mineral component in the tap water (mainly CaO) is less likely to adhere and accumulate, so that the heating efficiency does not decrease even after long-term use, and a highly reliable ceramic heater is provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a ceramics heater unit in which a pipe-shaped ceramics heater of the present invention is actually used.

FIG. 2 is a sectional view taken along line CC of FIG.

FIG. 3 is a perspective view of a plate-shaped ceramics heater of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramics heater 11 ... Ceramics base 12 ... Resistance heating element 13 ... Heating part 14 ... Electrode wiring 2 ... Glass 3 ... Ceramics -Ter unit outer frame 4 ... Packing

[Table 1]

Claims (4)

[Claims] 1. A ceramics heater in which a resistance heating element is embedded in a substrate made of ceramics, wherein the surface of the heating portion is covered with glass. 2. The ceramic heater according to claim 1, wherein the substrate made of ceramics has a pipe shape. 3. The ceramic heater according to claim 1, wherein the substrate made of ceramics has a plate shape. 4. The ceramic heater according to claim 1, wherein the surface roughness of the glass is RZ 1.6 or less.