JP2000228117A - Signal cable for high temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a signal cable capable of keeping a high insulation resistance value at high temperatures by using a silica gel manufactured from an aqueous solution containing sodium silicate as a raw material for an inorganic insulation material filled in a metallic sheath. SOLUTION: A member composed by filling an inorganic insulation material 2 of silica gel powder in a metallic sheath 1 of a stainless steel pipe having an inside diameter of 10 mm and an outside diameter of 13 mm so as to position a wire 3 having a wire diameter of 1.6 mm at the center is drawn to reduce its diameter until the outside diameter of the outside metallic sheath 1 of the stainless steel pipe reaches 1.6 mm, so that the filling density of the inorganic insulator 2 of the silica gel powder material inside the metallic sheath 1 of the stainless steel pipe is increased. The silica gel used in this case is formed by reducing and uniformly adjusting each diameter of fine holes of a silica gel provided by neutralizing sodium silicate with sulfuric acid by passing heated steam at 100-1000 deg.C through it in an autoclave. Thus, an insulation property of 102 Ω is improved by the use of the inorganic insulation material 2 provided by increasing the degree of porosity of pores of the silica gel, so that a resistance value of 107 Ωat 1000 deg.C can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal cable used for measurement and control in industrially used thermal equipment and equipment, and more particularly to a signal cable having improved electrical insulation in a high-temperature atmosphere. It is.

[0002]

2. Description of the Related Art In a conventional MI cable or sheath thermocouple, an inorganic insulating material to be filled in a metal sheath is obtained by mechanically pulverizing a mineral such as silica, magnesia or alumina, and sieving it appropriately. Particle size-adjusted ones have been used.

[0003]

SUMMARY OF THE INVENTION A signal cable which is electrically insulated by interposing an inorganic insulating material in a metal sheath has been developed.
When used in a high-temperature atmosphere of 00 ° C. or higher, the insulation resistance of the insulating layer decreases, resulting in weak signal current leakage.
In the example of the thermocouple, the leaked weak electromotive current causes the detected temperature to be different from the true temperature.

[0004] In order to solve this problem, attempts have been made to improve the inorganic insulating material that does not cause a decrease in insulating performance at high temperatures, for example, by seeking high-purity fused magnesia.
The above demand for accurate temperature measurement in a high-temperature atmosphere requires a higher-purity inorganic insulating material, which is expensive. Attempts were made to adjust the particle size of the inorganic insulating material to achieve close packing, but this has not yet been solved to solve the problem of insulation deterioration in a high-temperature atmosphere.

[0005]

In view of the above circumstances, the present invention has been made in view of the above circumstances. Instead of mechanically pulverized inorganic insulating material filled in a metallic sheath, the present invention uses an aqueous solution containing sodium silicate as a raw material. By using the manufactured silica gel, a signal cable that maintains a high insulation resistance value at a high temperature could be manufactured.

Here, the silica gel used was heated and steamed so that the pore diameter of the pores of the silica gel particles was 80 to 1000 ° in order to improve the electrical insulation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on specific embodiments shown in the accompanying drawings. In FIG. 1, a metal sheath 1 of a stainless steel tube having an inner diameter of 10 mm and an outer diameter of 13 mm filled with an inorganic insulating material 2 of silica gel powder so as to be centered on a conducting wire 3 having a wire diameter of 1.6 mm. Then, the outer diameter of the metal sheath 1 of the stainless steel pipe is reduced by a swaging machine until the outer diameter of the metal sheath 1 reaches 1.6 mm.
The packing density of the inorganic insulating material 2 of the silica gel powder inside was made dense.

The MI cable obtained as described above has a length of 1
The electric resistance between the conductive wire 3 cut into 00 mm and accommodated inside the metal sheath 1 of the stainless steel pipe and the metal sheath 1 of the outer stainless steel pipe was measured while increasing the temperature by 100 ° C. in a furnace. Measuring the insulation resistance of the inorganic insulation filled by the method described above has been adopted as the most suitable method for actual use of the MI cable or the sheath thermocouple.

As the silica gel used here, silica gel obtained by neutralizing sodium silicate with sulfuric acid and having a fine and uniform pore diameter adjusted by heating steam at 100 to 1000 ° C. in an autoclave was used. FIG. 2 shows a state in which a single conductor of the high-temperature signal cable is accommodated in a metal sheath. FIG. 3 shows a state in which a plurality (two) of the high-temperature signal cables are accommodated in a metal sheath.

[0010]

According to the present invention, as described above, a metal sheath is provided.
A conductor or thermocouple wire with an inorganic insulating material
High-temperature signal cable with reduced outer diameter of metal sheath
Wherein the inorganic insulating material is made of porous silica gel.
High temperature signal cable, MI cable or cable.
Use a thermocouple made of pure fused magnesia
100 mm per 100 mm section
Electric resistance is 10 at 0 ° C ^FiveCould only reach the order of Ω
Increase the porosity of the pores of the silica gel in the present invention.
10^TwoImproved Ω insulation
And at 1000 ° C for 10⁷Ω results in high
High temperature of MI cable or sheath thermocouple used at high temperature
Increased accuracy as a signal cable and expanded use range
Was.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a single conductive wire of a high-temperature signal cable of the present invention is accommodated in a metal sheath.

FIG. 2 is a perspective view showing a state where a single conductor of the high-temperature signal cable of the present invention is accommodated in a metal sheath.

FIG. 3 shows a plurality (two) of high-temperature signal cables of the present invention.
FIG. 4 is a perspective view showing a state where the lead wire is accommodated in a metal sheath.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal sheath 2 ... Inorganic insulating material 3 ... Conductor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Kagamihara 5-6-28 Kisaki, Akashi-shi Okazaki Manufacturing Co., Ltd. (72) Inventor Shigeo Wakamori 2- 1846 Kozoji-cho, Kasugai-shi, Aichi Prefecture Fuji Silysia Chemical Ltd. (72) Inventor Kazuhiko Yaguchi 2- 1846 Kozoji-cho, Kasugai-shi, Aichi F-term in Fuji Silysia Chemical Co., Ltd. 5G309 LA07 PA02 5G313 AB09 AC02 AC07 AD08 AE07 AE08 5G315 CA02 CB02 CB06 CC08 CD17 5G319 AA03

Claims (1)

[Claims] 1. A high-temperature signal cable in which a conductive wire or a thermocouple wire is accommodated in a metal sheath with an inorganic insulating material interposed therebetween, and the outer diameter of the metal sheath is reduced and reduced. High-temperature signal cable made of porous silica gel.