JPH0238395Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sheathed heater. A sheathed heater is constructed of an electrically heating resistance wire coil electrically insulated with heat-resistant electrically insulating powder, embedded in a metal tube, and having electrical connection terminals at both ends of the coil. When electricity is connected to the terminal, the heater generates heat and heats the object. Temperature control and safety control for electrically heated sheathed heaters are performed by an electronic control device having a temperature sensor, a thermostat, and the like. In many of these cases, the sheathed heater is incorporated into the mechanical equipment, and each of the above-mentioned management is performed simultaneously. However, in cases where the sheathed heater can be used in a movable state as a single unit, it may be necessary to insert a separate temperature control device or safety device into the electrical circuit of the sheathed heater to ensure safety. . Therefore, the present invention improves the unsafe sheathed heater that does not take such measures and provides an extremely safe sheathed heater with overheat prevention. Next, the present invention will be explained in detail with reference to the drawings of one embodiment.

FIG. 1 is a schematic diagram of one prior embodiment. When heating a liquid or the like 2 with a sheathed heater 1, a temperature sensor 4 such as a thermocouple is provided adjacent to the heater 1 placed in the liquid 2, and a temperature control device 5 is operated to control the sheathed heater 1. temperature control and safety management. Furthermore, by providing the temperature sensor 4 close to the heat generating part of the sheathed heater 1, it is possible to cut off the current supply immediately before abnormal overheating occurs. However, when the sensor 4
If it is too far away, it is difficult to quickly detect abnormal overheating and cut off the current supply. 6 is a wiring path, and E is a power supply.

FIG. 2 is a schematic external view of one embodiment of the present invention.
A terminal box 8 for electrical connection of the sheathed heater 7 is provided with a metal tube 9 containing a lead wire electrically insulated with heat-resistant electrical insulating powder, and a temperature fuse that contacts and melts is provided at the tip 9a of the metal tube 9. A cap-shaped current interrupting device 10 made of glass or ceramic and having a built-in hollow space is provided in a watertight and replaceable manner. The device 10 has its tip 10a
is provided close to or in contact with the heat generating portion 7a of the sheathed heater 7.

FIG. 3 is an enlarged side sectional view of the cap-shaped glass or ceramic current interrupting device 10 of FIG. The metal tube 9 has the device 10 replaceable and watertight at its end 9a, and has lead wires 9c and 9d electrically insulated with heat-resistant electrically insulating powder 9b. The tip 9e of the metal tube 9 is open and is configured to be screwed into and locked with the current interrupting device 10. The current interrupting device 10 made of glass or ceramic has a bottom portion 10 made as thin as possible so that the heat generating portion 7a of the sheathed heater 7 can be overheated quickly.
a, has a replaceable temperature fuse 10b, has a space 10c in which the fuse 10b melts and can be separated by the overheating, and is replaceable and watertightly screwed into the tip 9e of the metal tube 9. A shoulder 10f has a heat-resistant packing 10e which has a diameter of 10d and is watertight, and which allows the temperature fuse 10b to be pressed together with the threaded lock to the tips 9cp and 9dp of the lead wires.
constitutes the device 10. The bottom part 10a of the device 10 quickly transfers the abnormal overheating of the heat generating part 7a of the sheathed heater 7, blows out the temperature fuse 10b and separates the lead wire 9c,
The power supply to 9d is cut off. The temperature fuse 1
Once the fuse 0b is fused, the device 10 can be unscrewed from the tip 9e of the metal tube 9 and replaced with a separately provided temperature fuse 10 of the same rated capacity. Further, if the device 10 is damaged, it can be replaced with another device 10 of the same type.

As described above, according to one embodiment of the present invention, the attached safety device in the case of a movable type of single sheathed heater similar to the sheathed heater 7 is an independent electric circuit installed and used in conjunction with the sheathed heater. It has features such as the case used by being inserted into the device is eliminated, ensuring reliability in terms of safety, and the container such as the glass of the temperature fuse 10b or the current interrupting device 10 can be freely replaced. are doing.

[Brief explanation of the drawing]

FIG. 1: A schematic diagram of a previous embodiment. FIG. 2: A schematic external view of an embodiment of the present invention. FIG. 3 is an enlarged side sectional view of the replaceable glass or ceramic current interrupt device 10 of FIG. 2; 1... Sheathed heater, 1a... Heat generating part, 2...
...liquid, 3...container, 4...temperature sensor, 5...
...Electronic control unit, 6... Wiring path, E... Power supply, 7
... Sheathed heater, 7a ... Heat generating part, 8 ... Electrical connection terminal box, 9 ... Metal tube, 9a
... end, 10 ... replaceable current interrupting device made of glass or ceramic, 10a ... thin bottom,
10b...Replaceable temperature fuse, 10c...
A space where the temperature fuse can be separated, 10d...
Spiral part, 10e...Heat-resistant packing, 10f...
...Shoulder to press the temperature fuse, 9b...Heat-resistant electrical insulator, 9c, 9d...Lead wire, 9cp, 9
dp...Tip of lead wire, 9e...Opening tip.

Claims (1)

[Scope of utility model registration request] In a case where a heat-resistant tube is attached to the heat generating part of a sheathed heater to constitute a safety device such as a temperature fuse, the tube 9 has two lead wires electrically insulated with heat-resistant electrically insulating powder. A cap-shaped current interrupting device 10 made of glass or ceramic and having a hollow space 10c containing a temperature fuse that contacts and melts the lead wire terminal parts 9cp and 9dp of the lower tip part 9a of the tube 9 is connected to the terminal part 9a of the tube 9. A sheathed heater with overheating prevention, characterized in that the sheathed heater is watertight and replaceable, and is provided in close proximity to or in contact with the sheathed heater 7.