JPS6221960Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a thermosensor.

Conventional thermosensor thermocouples and thermistors accurately sense a wide range of temperatures, but they are expensive, making them difficult to use in mass-produced products.
The present applicant has developed a thermosensor in which a fusible member is housed with a powder insulator interposed in a metal tube, and has published Utility Application No. 55-152640 ``Thermosensor'' and Japanese Patent Application No. 1982-152640.
−149716 “Thermosensor” has already been filed. Incidentally, an alloy such as silver-zinc that melts at a predetermined temperature is used as the fusible member of this thermosensor, but since silver is a precious metal and is expensive, it is desirable to use as little fusible material as possible to function as a thermosensor. is required. but,
If the amount of the fusible member is too small, even if it melts at a predetermined temperature, it will not be able to conduct with other fusible members or the metal tube, and will not function as a thermosensor. Therefore, in the present invention, the density of the powder insulator of the fusible member is increased so that the fusible member can function as a thermosensor even if the amount of the fusible member is small.

Hereinafter, the present invention will be described in detail based on specific embodiments shown in the accompanying drawings.

In one embodiment of the present invention shown in Figs. 1 to 4, a long metal tube containing conductors 2, 2 with powder insulator 1 such as magnesium oxide (MgO) interposed therebetween is used as a thermosensor.
First, the metal tube is cut into pieces (Fig. 1). Usually, a long metal tube is squeezed over its entire length to reduce its diameter, and the metal tube is filled with powdered insulation 1. Next, a hole 4 is drilled in one end of the metal tube 3 (Fig. 2). A disk-shaped meltable member 5 is placed in the hole 4 at a slight distance (for example, about 0.3 mm) from the end faces of the conductors 2, 2, and the hole is filled with powdered insulation 1, and the powdered insulation 1 is compressed to increase its density (Fig. 3).
The meltable member 5 is an alloy of silver-zinc or the like that melts at a predetermined temperature, and is set by mixing appropriate amounts of each metal so that it melts at the temperature to be detected. Next, one end of the metal tube 3 is closed with a lid 6 by welding or the like (FIG. 4).

FIGS. 5 to 7 show other embodiments, in which a disc-shaped ceramic 7 is housed in the hole 4 in addition to the fusible member 5, and there is only one conductor 2 (FIG. 6). In some cases, the fusible member 5 is rod-shaped (FIG. 7), but in either case, the powder insulator 1 in the vicinity of the fusible member 5 is pressurized to increase its density.

Next, the effect will be explained.

FIG. 8 shows an outline of a high temperature alarm device using a thermosensor of the present invention. The thermosensor is connected in series to a warning light 8 and a battery 9, and when the thermosensor reaches a predetermined temperature, the fusible member 5 melts. When it is in contact with another fusible member 5 or metal tube 3 and electrically conductive, a warning light 8 lights up.

Because the fusible member 5 uses precious metals such as silver, it is desirable to use as little as possible. As a result of experiments, it has been found that it is essential to increase the density of the powder insulator 1 in the vicinity of the fusible member 5. This is because a small amount of the fusible material 5 melts and expands slightly in volume, allowing the high-density powder insulator 1 to increase the pressure and sufficiently diffuse the material while minimizing the formation of gaps inside the powder insulator 1. By communicating and conducting with the fusible member 5 or the metal tube 3.

Since the present invention has the above-mentioned configuration, in a thermosensor in which a powder insulator is interposed in a metal tube and a conductor and a small amount of a fusible member are housed at a certain distance from the conductor, the fusible member made of a noble metal can be used. It is possible to reduce the amount as much as possible, making it possible to provide an inexpensive thermosensor.

[Brief explanation of drawings]

1, 2, 3, and 4 are partially sectional front views, and FIGS. The figures are respectively partially sectional front views of other embodiments of the thermosensor of the present invention, and FIG. 8 is an electrical circuit diagram showing an outline of a high temperature alarm device using the thermosensor of the present invention. 3...Metal tube, 1...Powder insulator, 2...Conducting wire, 5...Fusible member.

Claims (1)

[Scope of utility model registration request] A thermosensor comprising a conductor and a small amount of a fusible member separated from the conductor by a powder insulator interposed in a metal tube to increase the density of the powder insulator near the fusible member.