JPS6259876B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheathed heater, and in particular, it is an object of the present invention to provide a sheathed heater that has both rapid heating properties and long life, and is easy to manufacture.

As a conventional high temperature sheathed heater, the surface temperature is
It took 2 minutes to 2 minutes and 30 seconds to reach around 800°C, and when this sheathed heater was used in a cooker, it was not able to meet the market demand for faster cooking. On the other hand, rapid heating properties can be expected by using molybdenum wire or tungsten wire, which have a large positive temperature coefficient of resistance, as the heating wire, but in this case, the life of the heating wire is short, and the sheathed heater's original There was a disadvantage that the advantage was lost.

The present invention solves the above-mentioned conventional drawbacks, and also
The present invention aims to provide a sheathed heater that is easy to manufacture, and embodiments of the present invention will be described below with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a heating wire having round rod-shaped terminals 2 at both ends, and is inserted into a metal pipe 3. 4 is an insulating powder such as magnesia filled in the metal pipe 3. 5 is a glass sealing material that seals the openings at both ends of the metal pipe 3. Heating wire 1 has a diameter
A double heating wire 1 made into a coil by simultaneously winding a 0.2 mm molybdenum wire 6 and a 0.2 mm diameter nichrome wire 7 around a winding rod with a winding diameter of 1.8 mm is connected to a 2.0 mm diameter terminal 2.
It is spot welded on. Note that a tungsten wire or a tungsten-molybdenum alloy wire may be used instead of the molybdenum wire 6, and an iron-chrome wire may be used instead of the nichrome wire 7.

In the above configuration, the resistance value of the molybdenum wire 6 is small at the initial stage of energization, and a rapid temperature rise can be expected. For example, it took about 50 seconds for the surface temperature to reach 800°C. In addition, the resistance value of the molybdenum wire 6 increases as the temperature increases, and
When the temperature reaches ℃, the resistance value becomes almost the same as that of the nichrome wire 7, and it becomes stable and has a long life. Further, since the winding diameters of the molybdenum wire 6 and the nichrome wire 7 are the same, the terminal 2 can remain in the shape of a round bar, making processing easier.

As described above, according to the present invention, the heating wire is made by connecting a tungsten wire, a molybdenum wire, or a tungsten-molybdenum alloy wire, and a nichrome wire or an iron-chrome wire in parallel with the same winding diameter. By making the winding diameter the same, the wire only needs to be wound once, and the terminals connected to both ends of the heating wire can remain in the shape of a round bar. This has the excellent effect of extending the lifespan.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a sheathed heater showing an embodiment of the present invention, and FIG. 2 is a front view of heating wires of the sheathed heater. 1... Heating wire, 2... Terminal, 3... Metal pipe, 4... Insulating powder, 6... Molybdenum wire, 7...
...Nichrome wire.

Claims (1)

[Claims] 1. In a sheathed heater in which a heating wire equipped with round bar-shaped terminals at both ends is inserted into a metal pipe and filled with insulating powder, the heating wire is made of a tungsten wire, a molybdenum wire, a tungsten-molybdenum alloy wire, a nichrome wire, or a tungsten-molybdenum alloy wire. A sheathed heater characterized by being connected in parallel with an iron chrome wire with the same winding diameter.