JPS598295A - Sheathed heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horn heater used at a high temperature of 650° C. or higher among heating elements of electric heating appliances.

Conventionally, this type of heater has normally sealed both ends of a metal pipe with a noon made of low-melting glass to prevent the insulation properties of the filling material made of Magnenor powder from deteriorating under high temperature and high humidity conditions. However, this glass cannot be heated to a high temperature during sealing, and when it reaches room temperature, the inside of the 7-Z heater becomes negative pressure and moisture infiltrates, causing a decline in the insulation properties of the 7-Z heater at high temperatures. There is.

The wooden invention was made in relation to the above, and its purpose is to obtain a heater whose stability does not deteriorate at high temperatures. In order to achieve this purpose, the filling material is made by mixing 0.5 to 5% wt of bulk mullite fine powder with magneur powder.

An embodiment of the wooden invention will be described below with reference to the drawings. 1 is a metal pipe, 2 is a terminal, 3 is a heater wire, 4 is magnesia powder 7 (40 to 325 meth/yu) and a bulk murai (A/l203-Si02) fine powder 6 (100 meth/yu) The filling material 5 is a mixture of 0.05 to 5% wt. 5 is a glass made of low melting point glass.

Filling the filling fee 4 and sealing the fee 5 can be done in the same way as before.

The operation of the above configuration will be explained. The fine mullite powder 6 is the second
As shown in the figure, it forms a soft crystal, and this is mixed with magnesia powder 7 at 0.5 to 5% wt to form the filling material 4.

In this state, the voids between the magne/a powders 7 and 7 are filled with softer crystals, eliminating voids and improving thermal conductivity.Since the substance is made of mullite, it has good heat resistance.
In addition, the suspension of fine mullite powder 6 is less than 0.5 wt, so it is ineffective when used at high temperatures, and the filling rate of magneur powder 7 becomes poor when it is more than 5% wt.

When the displacement is within the range of 0.5 to 5%wt, the thermal conductivity of the filling material 4 is about twice that of the conventional one.

Therefore, heater wire 3. Even if the filling material 4 reaches a high temperature, the heat is well dissipated, the moisture resistance is improved in addition to the heat resistance, and the insulation properties are not deteriorated. To explain the effect in Figure 3, the insulation resistance value of A using conventional magneur powder is 1M.
The temperature when the same value was shown was 800°C, but in Example B, the temperature when the same value was shown was 880°C.

Note that the sealing of the seal 5 may be omitted.

As described above, according to the present invention, it is possible to obtain a sheathed heater whose insulation properties do not deteriorate at high temperatures, and it is also possible to eliminate the need for a seal.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a sheathed heater according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the same essential part, and Fig. 3 is a temperature and insulation resistance value of the same sheathed heater B and a conventional one A. FIG. 4... Filling material 6... Bulk fine mullite powder. 7... Magnenia powder. Applicant: Hitachi Thermal Appliances Co., Ltd.

Claims (1)

[Claims] Filling the metal pipe with heating wire and filling material/-
1. A zone heater, characterized in that a filling material (4) is formed by mixing bulk mullite fine powder (6) with a magnia powder (7) at a weight of 05 to 5%.