JPS60254588A - Hollow 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] Technical field of invention] The present invention relates to a hollow sheathed heater.

In particular, it is an object of the present invention to provide a hollow sheathed heater with high local heating efficiency.

(Prior Art) As shown in FIG. 1, a conventional hollow sheathed heater has a heating coil 2 inside an outer metal pipe 1 with terminals 3 and 4 connected to both ends.
An inner metal pipe 5 is further inserted inside the heating coil 2 and supported approximately concentrically with respect to the outer metal pipe 1, and each gap is filled with heat-resistant electrical insulating powder 6 such as magnesia powder. It was something. The main use of such a hollow sheathed heater is to heat a fluid such as water or air by flowing it inside the inner metal pipe 5. In the conventional structure, since the diameter of the outer metal pipe 1 is large, the surface area is large, and the amount of heat lost from this surface is large. As a result, there is a drawback that the heating efficiency for the fluid becomes low (21).Therefore,
In order to increase heating efficiency, it is common practice to apply a heat insulating material (not shown) to the outer periphery of the outer metal pipe 1 to prevent heat loss from the outer metal pipe 1. In such a case, installation of the heat insulating material is expensive, and problems such as an increase in external dimensions occur.

[Summary of the invention]

The present invention solves the above-mentioned problems, the heating efficiency is low, and
The purpose is to provide a hollow sheathed heater with a small external design and low cost, and will be described in detail below based on an embodiment of the present invention shown in FIG.

Embodiments of the Invention] In Fig. 2, 10 is an outer metal pipe made of iron, stainless steel, or copper, and 11 is an outer hollow molded body formed by molding and firing a heat-resistant electrical insulating powder containing 1, for example, 81. It is composed of extremely high amounts of magnesia powder. A heating coil 12 has terminals 13 and 14 connected to both ends thereof, and is inserted into the hollow of the outer hollow molded body 11 so that the terminals 13 and 14 are led out of the outer metal pipe 10. 15 is an inner hollow molded body formed by molding and firing heat-resistant electric insulating powder inserted inside the heating coil 12; 9, for example, purity 100;
It is composed of % magnesia powder. Reference numeral 16 denotes an inner metal pipe inserted into the hollow of the inner hollow molded body 15, and is a pipe made of stainless steel or copper. Reference numeral 17 indicates temporary plugs inserted into both ends of the outer metal pipe 10, and reference numeral 18 indicates magnesia powder filled in each gap between the outer metal pipe 10 and the inner scrap metal pipe 1G.
It is 98% magnesia powder.

According to the above configuration, an insulating layer with good thermal conductivity is provided on the inside of the 9 heating coils, and an insulating layer with poor thermal conductivity is provided on the outside, so in such a hollow sheathed heater,
When used by flowing a fluid such as water or night air into the inner metal pipe 16 9 Since the inner insulating layer of the heating coil 12 is made of a material with good thermal conductivity, the inner metal pipe 16
Heat transfer to the side is better than to the outside, and the heating efficiency for the fluid is extremely high.

On the other hand, the heating coil 12 is connected to the outer metal pipe 10 side.
Since the outside of the metal pipe 10 is composed of an insulating layer with poor thermal conductivity, heat loss is small, and there is no need to provide insulation material around the outer periphery of the outer metal pipe 10, so the external size can be configured to be small and the price is low. It is possible to obtain a hollow sheathed heater of extremely practical value as it can be made at low cost.

〔Effect of the invention〕

As explained above, according to the present invention, heat loss is small;
A hollow sheathed heater with high heating efficiency can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional hollow sheathed heater, and FIG. 2 is a sectional view showing a hollow sheathed heater of the present invention. In the figure, 10 is an outer metal pipe, 11 is an outer hollow molded body,
12 is a heating coil, 13 and 14 are terminals, 15 is an inner hollow molded body, 16 is an inner metal pipe, 17 is a temporary plug, and 18 is magnesia powder. Lover Masuo Oiwa (2 others) Figure 1 Figure 2

Claims (1)

[Claims] A hollow molded body made of a heat-resistant electrical insulator with good thermal conductivity is inserted inside a heating coil with terminals connected to both ends, and a heat-resistant electrical insulator with a lower thermal conductivity than the hollow molded body is inserted on the outside. A hollow molded body is inserted into the outer metal pipe, and an inner metal pipe is inserted into the hollow molded body inserted inside the heating coil to create a valley gap between the inner metal pipe and the outer metal pipe. A hollow sheathed heater characterized by being filled with heat-resistant electrical insulating powder.