JPS6015111B2 - Sea heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheathed heat coil which is formed by filling a heat-resistant electrical insulator between a heating wire coil having terminal rods at both ends and a sheathed metal pipe to reduce the diameter. The present invention aims to provide a sheathed heater that is improved.

Conventionally, in a sheathed heater, only magnesia powder was filled as a heat-resistant electrical insulator between a heating wire coil 2 having terminal rods 1 at both ends and a covered metal pipe 3, as shown in Fig. 1. This has the disadvantage that it absorbs moisture, leading to a decrease in electrical insulation between the heating wire coil 2 and the outer covering metal pulp 3.

In order to prevent this, various methods of sealing the ends of the sheathed metal pipes have been devised, but none of them have been perfect in terms of mechanical strength and cost, and have advantages and disadvantages.

In addition, by imparting water repellency to the filler, it has moisture-resistant insulation properties and can be used as a key seal, but it has been put into practical use, but because silicone resin is used as the water repellent, the heat resistance limit is low, for example at 400 degrees Celsius. , there was a demand for a sheathed heater that was applicable only to low-temperature sheathed heaters and could be used at even higher temperatures. The present invention satisfies these needs and provides a sheathed heater using a water repellent agent with improved heat resistance so that it can be used at higher temperatures than conventional water repellent agents.

Examples of the present invention will be described below with reference to FIGS. 2 to 5.

In the figure, 11 is a heating wire coil equipped with terminal bars 12 at both ends, 13 is a covered metal pipe, and 14 is a heating wire coil 1.
1 and an inorganic oxide filled between the outer metal pipe 13,
For example, a heat-resistant electrical insulator made of magnesia powder Mg○, 15
is a twilling agent mixed and deposited on this heat-resistant electrical insulator 14.

Twill water agent 15 is a mixture of 30 to 9% by weight of methyl silicone resin and 10 to 7% by weight of filler,
Furthermore, this filler contains 20-8% by weight of silicon dioxide Si02 and 20-80% by weight of calcium oxide Ca○.
It is a powder having a particle size of less than loAm and having a composition of In addition,
Calcium silicate ores of the zo)trito or wollastonite type can be used as fillers. A mixture of the sheath heat external water spray agent 15 of this embodiment and magnesia powder, which is a heat-resistant electrical insulator 14, is prepared, and a heating wire coil 11 and a sheathed metal pipe 13 having terminal fins 12 at both ends are prepared. It is obtained by filling the space with the above mixture, reducing the amount, and then heating to a temperature at which the silicone resin melts.

It has the feature that the silicon resin is bonded to silicon dioxide by the calcium ions Ca contained in the sheath heat outer filler using the above-mentioned water purification agent 15, and the heat resistance is improved.

For example, an example of a silicon dioxide filler containing calcium ions is 50.7% silicon dioxide and 47% silicon dioxide filler.
A sheathed heater using a rehydration agent made by mixing equal amounts of B wollastonite (natural wollastonite) containing 4% calcium oxide with methyl-based silicone resin repels only the silicone resin with water, as shown by the solid line A in Figure 4. The upper limit temperature of water repellency is approximately 100 qC higher than that of the conventional sheathed heater (solid line) used as the agent.

In addition, when analyzed by TGA spectroscopy, as shown in Figure 5, the sheathed heater using a water solution containing calcium ions not only has a smaller heat loss rate than the conventional sheathed heater mentioned above, but also The heat loss rate is smaller and the thermal efficiency is higher especially at 450 to 600° C. where it is used, compared to a sheathed heater using a purification agent containing cations such as sodium ion Na+ or potassium ion K+.

In Fig. 4, C, 2, and T indicate the heat loss of the water repellent agent of the sheathed heater of this example, the conventional sheathed heater mentioned above, and the sheathed heater using a water repellent agent containing other cations, respectively. It shows the rate. Furthermore, in the sheathed heater of this embodiment, when used at abnormally high temperatures, the water repellent agent 15 becomes silicon dioxide or calcium oxide, which has high electrical insulation properties, and there is no risk of the electrical insulation resistance decreasing. As is clear from the above explanation, the sheath heater of the present invention does not cause insulation deterioration even in a high humidity atmosphere, and has improved heat resistance of approximately 100°C compared to the conventional one that uses only silicone resin for the wicking agent. It has the effect of being able to be used regularly at high temperatures and is of great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional sheathed heater, Fig. 2 is a sectional view of a sheathed heater showing an embodiment of the present invention, and Fig. 3 is a sectional view of a sheathed heater according to an embodiment of the present invention.
FIG. 4 is an enlarged view of part A in the figure, FIG. 4 is an upper limit heating temperature time characteristic diagram of the sheathed heater of this embodiment and the conventional sheathed heater, and FIG. It is a thermal loss rate time characteristic diagram of a twill water agent. 11...Heating wire coil, 12...Terminal shank,
13...Sheathed metal pipe, 14...Heat-resistant electrical insulator, 15...Water repellent agent. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A sheathed heater formed by filling a heat-resistant electrical insulator between a heating wire coil having terminal bars at both ends and a sheathed metal pipe to reduce the diameter, which is made of a calcium compound and silicon dioxide. A sheathed heater comprising a mixture of a filler and a silicone resin mixed and deposited on the heat-resistant electrical insulator. 2. The sheathed heater according to claim 1, wherein the calcium compound is calcium oxide.