JPS6019116B2 - Sea heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheathed heater, and particularly to an insulation structure between a metal pipe at the end of the metal pipe and a lead-out terminal of a heating wire. The purpose of this invention is to securely insulate the metal pipe from the lead terminal, simplify the insulation work, and eliminate wasted space at the end of the metal pipe.

As shown in Fig. 2, a heating wire 2' is inserted into a metal pipe 1' in a non-contact state, and the insulation between the metal pipe 1' and the heating wire 2' is This is done using insulating powder 3'.

In addition, the above-mentioned heating wire 2' is burnt on the similar part of the metal pipe 1'.
Although insulation from the lead-out terminal 2a' is performed by an insulator tube 4', this structure has the following drawbacks. In other words, the dimension t between the end of the metal pipe 1' and the end of the insulating powder 3' differs for each product due to variations in the filling operation of the insulating powder 3'.

Therefore, the insulator 4' must be long enough to take this variation into consideration. In other words, if this insulator 4' sinks into the metal pipe 1 due to the armor, the metal pipe 1'
Therefore, it becomes impossible to maintain a sufficient insulation distance between the heating wire 2' and the lead-out terminal 2a'. However, insulator 4'
If the insulator 4' is made too long, the insulator 4' will protrude too far from the end of the metal pipe 1', creating a wasted space at the end of the metal pipe 1', and this space will be used for the product to which this sheathed heater is installed. In addition, with this structure, an auxiliary fixing material 5' such as silicone rubber is required to fix the insulator 4', which is a laborious process. Met.

Therefore, in the present invention, liquid silicone rubber or an organic solvent solution of silicone rubber and a particle size of 20
This method attempts to solve the above-mentioned drawbacks of the conventional method by injecting and solidifying a mixed liquid containing an inorganic powder of less than 100 ml.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In Fig. 1, 1 is a metal pipe, and this metal pipe 1
A heating wire 2 is inserted in a non-contact manner.

The metal pipe 1 and the heating wire 2 are insulated by an insulating powder 3 filled in the metal pipe 1.

Further, the heating wire at the end of the metal pipe 1 is insulated from the lead terminal 2a of the heating wire 2 by an insulator 4.

With the above structure, the insulator 4 is made by filling the end of the metal/guipure with liquid silicone rubber or a mixture of an organic solvent solution of silicone rubber and an inorganic powder having a particle size of 20 mm and solidifying it. This will be explained in detail below. First, a 13.3 W% xylene solution of silicone RTV rubber and Mg0 powder of 4 grains were mixed at a weight ratio of 3.
: Prepare a liquid mixed in a ratio of 2.

Next, this liquid is injected into the end of the metal pipe and allowed to solidify, but the solidification time varies greatly depending on the temperature of the metal/end of the pipe. In other words, if the end of this metal pipe is 25 qo (same as room temperature), it will take several hours to solidify, but it will take 100 qo (in order to braze this sheathed heater to the back of the hot plate). If it is in a state where it has been passed through), the solidification time will be very short. Note that when fixed in this manner, the amount of Mg0 in the insulator 4 is 83.3 wt%.
Of course, it is possible to increase the amount of Mg○ to 100 wt%, but in order to make this insulator 4 have twill properties, it is better to add silicone rubber, even if it is a small amount, and this will improve its insulation properties. . Next, change the particle size to 20 degrees of Mg.
○ Explain the reason for using (inorganic powder) powder. In other words, the larger the particle size of the Mg◯ powder, the faster the time for the Mg carp powder and silicone rubber to separate and separate into two layers.

According to experiments, when the particle size of the Mg○ powder was 4, it separated for about 1 hour, and when the particle size was 20, it separated instantaneously, and during this time, the time gradient was almost proportional. Here, we will discuss the disadvantages of separating into two layers. That is, when the Mg○ powder and the silicone rubber are separated into two layers, the silicone rubber layer, for example, generates heat due to contact resistance with the lead-out terminal 2a at the end of the heating wire 2, and this lead-out terminal 2a becomes When it reaches 400 o'clock, it becomes tattered. As a result, the insulation between the heating wire 2 and the lead-out terminal 2a at the end of the metal/gupoo cannot be reliably achieved. Therefore, it is necessary to solidify the Mg0 powder before this separation occurs, but as mentioned above, when the particle size of the Mg0 powder reaches 20 μm, it will instantly separate, so this separation cannot be prevented.

However, when the particle size of the Mg0 powder becomes 19A, the above separation time takes about 4 minutes.

So, all you have to do is let it solidify during these 4 minutes.
In order to solidify in such a short time, it is possible to sufficiently achieve this by using acetone or the like as an organic solvent for silicone rubber.

In the above embodiment, Mg◯ powder was used as the inorganic powder, but other metal oxides may be used. As described above, according to the present invention, even if the distance between the end of the metal pipe and the insulating packader varies, this variation can be absorbed because the above-mentioned mixed liquid is injected into the same metropolitan area and solidified. . Therefore, the end of the metal pipe is reliably insulated from the heating wire.

In addition, the insulation work is extremely simple and has good workability because it only involves injecting the above-mentioned thirst liquid. Furthermore, in the present invention, since the insulator does not protrude significantly from the end of the metal pipe, it does not impair the compactness of the product to which the sheathed heater is attached.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a sheathed heater according to an embodiment of the present invention, and FIG. 2 is a sectional view of an electrical part of a conventional example. 1... Metal pipe, 2... Heating wire, 3... Insulating powder, 4... Insulator. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a sheathed heater in which a heating wire is inserted into a metal pipe in a non-contact state and the metal pipe is filled with insulating powder to insulate the metal pipe and the heating wire, liquid silicon is placed inside the end of the metal pipe. A sheathed heater characterized in that a liquid mixture of an organic solvent solution of rubber or silicone rubber and an inorganic powder having a particle size of less than 20 μm is injected and solidified.