JPH11214122A - Sheath heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheath heater which can be used easily at low cost and has satisfactory water-tightness. SOLUTION: This sheath heater is constituted in such a way that an electric wire with insulation covering 8 is attached to an electrode rod 1, a heat shrinking tube 10 having a two layer structure having heat melting adhesive as an inner layer material is heat-shrunk and adheres closely to cover a part of the electrode rod 1 and the electric wire with insulation covering 8, and a heat. shrinking tube 12 having a two-layer structure having heat melting adhesive as an inner layer material is heat-shrunk and adheres closely to cover the heat shrinking tube 10 and a pipe 3 at an end of the sheath heater. Consequently, it is possible to provide a sheath heater which is inexpensive and has a water- tight performance because water-tightness equal to that of a conventional sheath heater or more is kept, exclusive mold and molding machine are not required, and machining is completed in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheathed heater widely used as an electric heat source for cooking, heating and the like, and more particularly, to dew condensation on an end of a sheathed heater of an electric water heater, a sanitary washing toilet seat, a hot water circulating warming device for a bath, and the like. The present invention relates to a sheathed heater which is used for a product exhibiting water droplets or water droplets.

[0002]

2. Description of the Related Art Conventional sheathed heaters are used in general electric cooking appliances and heating appliances because of their high safety and excellent corrosion resistance. In recent years, electric water heaters, sanitary washing toilet seats, and hot water circulating heat insulating devices for baths have been used. It is also used as a heat source for hot water.

Generally, this sheathed heater inserts a coil-shaped heating wire having electrode rods at both ends into the center of a metal pipe, fills this metal pipe with an electrically insulating powder such as magnesia powder, and then reduces the rolling diameter. Manufactured.

In such a sheathed heater, an insulating material such as a silicon tube is generally inserted between an electrode rod serving as a charged part and a pipe serving as a non-charged part between the electrode rod and the inner surface of the pipe. The surrounding area of the contact surface is filled with room-temperature-curable silicone rubber to maintain the insulation distance.However, since the silicone rubber and the inner surface of the pipe and the electrode rod are incompletely water-tight, water droplets are particularly generated at the end portion. In the case where the pipe is hung or used entirely in water, as shown in FIG. 2, the entire pipe end is covered with vulcanized rubber 13 such as silicon rubber by integral molding to ensure water tightness. Further, after inserting a rubber molded product 14 shown in FIG. 3 into a terminal portion, the interior is filled with a room-temperature-curable silicone rubber 11.
There is a proposal as in Japanese Patent Publication No.

[0005]

In the prior art shown in FIG. 2, there is a problem that a special molding die and a molding machine are required, and time is required for vulcanizing the rubber, so that the cost is increased. Also,
In the conventional example shown in FIG. 3, there is a problem that the cost is increased since a dedicated molding die and a molding machine are required to manufacture the rubber molded article 14, and furthermore, the room temperature curing silicone rubber 11 filled therein is completely cured. Takes several days, and during this time, there is a problem that the sheathed heater cannot be used.

[0006]

In order to solve the above-mentioned problems, in the present invention, an electric wire with insulation coating is attached to an electrode rod of a sheathed heater, and a heat fusible material is provided so as to cover a part of the electrode rod and the electric wire with insulation coating. A two-layer heat-shrinkable tube having a heat-meltable adhesive as an inner layer material so as to cover the heat-shrinkable tube and an end pipe of the sheathed heater by heat-shrinking a two-layer heat-shrinkable tube having an adhesive as an inner layer material. The shrink tube is heat shrunk and adhered.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an end of a sheathed heater is double-covered with a heat-shrinkable tube. According to such a configuration, the heat-shrinkable tube having the two-layer structure using the heat-meltable adhesive as the inner layer material is melted during heat shrinkage, and then adheres and solidifies after cooling. Is easily watertight. Using a heat-shrinkable tube having this property, the electrode rod and a part of the wire with insulation coating are covered.
By covering the end pipe with a heat shrink tube, water tightness can be obtained more than before, and the equipment required for processing can be inexpensive, such as a handy dryer, and can be heat shrunk. Since processing can be performed in a short processing time and a short time, expensive dedicated equipment is not required, and a finished product which is inexpensive and can be used immediately is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG.

A coil-shaped heating wire 2 having electrode rods 1 at both ends is connected to a metal pipe 3 made of a corrosion-resistant and heat-resistant superalloy NCF800.
After filling the metal pipe 3 with the electrical insulating powder 4 made of magnesia powder, the metal pipe 3 was rolled and reduced in diameter, bent and pressed into a U-shape, and the flange 5 was made of brazing material 6. After mounting with brazing, both ends are glass 7
To form a sheathed heater.

Further, the electric wire 8 with insulation coating is connected to the electrode rod 1 through the connection terminal 9 by electric resistance welding, and a hot-melt adhesive is applied so as to cover the electrode rod 1 and a part of the electric wire 8 with insulation coating. The heat-shrinkable tube 10 having a two-layer structure as an inner layer material is subjected to heat shrinkage by applying heat of a dryer or the like for several tens of seconds, so that the electrode rod 1 is brought into close contact with a part of the insulated wire 8.

Here, a small amount of room-temperature-curable silicone rubber 11 is filled between a part of the electrode rod 1 exposed between the heat-shrinkable tube 10 and the magnesia powder and the inner wall of the pipe 3. However, this work is performed in order to secure the legal insulation distance between a part of the exposed electrode rod 1 and the inner wall of the pipe 3. When the diameter of the pipe is large and the insulation distance is longer than the regulation, silicon is required. No rubber 11 filling is required.

Next, a two-layer heat-shrinkable tube 12 having a heat-meltable adhesive as an inner layer material is similarly applied to the heat-shrinkable tube 12 to cover the heat-shrinkable tube 10 and the sheathed heater end pipe 3 with heat of several tens of millimeters. The heat-shrink tube 10 and the sheath-heater end pipe 3 are brought into close contact with each other by heat-shrinking for 2 seconds, thereby completing the sheath heater of the present invention.

[0013] In the sheathed heater thus obtained, the whole except for the terminal portion of the insulated wire was immersed in water and subjected to a three-month watertightness test. It has been confirmed that it has a watertightness equal to or better than that of the whole covered by integral molding with vulcanized rubber such as silicon rubber.

[0014]

According to the present invention, an electric wire with insulation coating is attached to an electrode rod of a sheathed heater, and a two-layered material made of a hot-melt adhesive is used to cover a part of the electrode rod and the electric wire with insulation coating. The two-layer heat-shrinkable tube having a heat-meltable adhesive as an inner layer material is heat-shrink-adhered so that the heat-shrinkable tube of the structure is heat-shrinked and adhered, and further, the heat-shrinkable tube is covered with the end pipe of the sheath heater so as to cover the heat-shrinkable tube. Accordingly, a sheathed heater having watertightness can be obtained at a low cost because the processing is completed in a shorter time without requiring a dedicated mold and a forming machine while maintaining watertightness equal to or higher than that of the conventional product. Further, since the shrinkage is completed in a short time, the sheathed heater can be used immediately after the processing is completed, and the usability is extremely improved.

[Brief description of the drawings]

FIG. 1 is a partially sectional side view of a sheathed heater according to an embodiment of the present invention.

FIG. 2 is a sectional view of a sheathed heater showing a conventional example.

FIG. 3 is a sectional view of a sheathed heater showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode rod 3 Metal pipe 8 Insulated wire 10 Heat shrinkable tube 12 Heat shrinkable tube

Claims (1)

[Claims] An electric wire with insulation coating (8) is attached to an electrode rod (1) of a sheathed heater, and a hot-melt adhesive is applied so as to cover the electrode rod (1) and a part of the electric wire (8) with insulation coating. A heat-meltable adhesive is applied to the heat-shrinkable tube so as to cover the heat-shrinkable tube (10) and the end pipe (3) of the sheathed heater so that the heat-shrinkable tube (10) having a two-layer structure as the inner layer material is adhered to the heat-shrinkable tube. A sheathed heater characterized in that a heat shrinkable tube (12) having a two-layer structure is heat-shrinked and adhered.