JPH1048061A - Thermocouple - Google Patents

Abstract

PROBLEM TO BE SOLVED: To find the deterioration of the thermocouple with the simple structure, by inserting a thermocouple of which a point part is a measuring junction, and a pipe having an opening at one end, into a metallic protecting tube of which a point part is closed, filling a gap between the pipe and the metallic protecting tube with an electrically insulating material of high thermal conductivity, and performing the diameter reducing working to the metal protecting tube. SOLUTION: A pair of thermocouples 2 of which the point parts 2a are welded to be a measuring junction, are inserted from the point parts 2a thereof, into one end part 1b of the other base having an opening, of a metallic protecting tube 1. Then a metallic pipe 3 of which a point part 3a of a diameter smaller than that the metallic protecting tube 1, is closed, and the other end part 3b is opened, is inserted into the metallic protecting pipe 1 from the point part 3a side. The thermocouple 2 and the pipe 3 are installed in parallel with each other on a symmetrical position to a central axis in the metallic protecting tube 1. Further an inorganic powdered insulating material 4 such as MgO is filled between the metallic protecting tube 1, and the thermocouple 2 and the pipe 3, and the opened one end part 1b is sealed by a mold sealing material such as a resin, when necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermocouple used for measuring a temperature.

[0002]

2. Description of the Related Art Thermocouples are widely used for heating furnaces and other temperature measurements. However, if used in a high-temperature atmosphere for a long period of time, there is a risk of deterioration.

Conventionally, there is no good method for detecting deterioration, and a comparison test is periodically performed with a reference thermocouple, or empirical replacement is performed every time a predetermined time is used.

[0004]

However, in order to perform a comparative test, it is necessary to prepare an expensive test device, which requires a great deal of time for the test such as removal of a thermocouple. It is difficult to correctly calibrate the thermocouple with the test device by making the temperature distribution in the length direction of the thermocouple different from that of the actual measurement condition. Further, when the thermocouples are simply replaced periodically, the periods of deterioration are different from each other, and even the usable thermocouples may be replaced, which may cause waste.

An object of the present invention is to provide a thermocouple in which the deterioration of a thermocouple can be easily known with a simple configuration in view of the above points.

[0006]

According to the present invention, a thermocouple having a temperature measuring contact and a pipe having an opening at one end are inserted into a metal protection pipe having a closed tip, and at least the pipe and the metal protection pipe are inserted. This is a thermocouple formed by filling an electrical insulating material excellent in heat conduction between the two and filling the metal protective tube with a reduced diameter.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing one embodiment of a manufacturing method according to the present invention. In FIG. 1A, 1
Has a tip 1a closed, for example, a length of 1 m and an outer diameter of about 2
A thick metal protection tube having a thickness of about 0 mm and a thickness of about 1 to 3 mm, and a tip 2a is welded from one end 1b of the other base portion of the metal protection tube 1 which is opened. A thermocouple 2 consisting of a pair of thermocouple wires is inserted into the metal protection tube 1 from its tip 2a.

[0008] Next, as shown in FIG.
A tip 3a having a smaller diameter and an outer diameter of about 5 mm is sealed, and a metal pipe 3 having the other end 3b opened is inserted into the metal protection tube 1 from the tip 3a. At this time, for example, the thermocouple 2 and the pipe 3 are provided in parallel at a substantially symmetric position with respect to a central axis in the metal protection tube 1.

[0009] Further, as shown in FIG.
An inorganic insulating powder 4 such as MgO, which is excellent in heat conduction, is filled between the thermocouple 2 and the pipe 3. One end 1b of the opening of the protective tube 1 is sealed with a mold sealing material 5 such as resin (shown in FIG. 2). The sealing material 5 includes the thermocouple 2 and the pipe 3
Can also be positioned.

Then, the diameter of the metal protection tube 1 including the thermocouple 2 and the pipe 3 inside is reduced by a swaging machine or the like, and the powdered insulating material 4 is tightly fixed to enhance heat conduction. Together with a predetermined diameter. At this time, the thermocouple 2 and the pipe 3 also extend and reduce in diameter by a predetermined amount. However, the inside diameter of the space inside the pipe of the pipe 3 is reduced in diameter enough to insert the reference thermocouple 6.

As described above, the metal protective tube 1 tightly filled with the insulating material 4 is heat-treated at a predetermined temperature to remove processing distortion and the like, and then, if necessary, the length of the thermocouple 2 and the pipe 3 is required. Process to length.

As shown in FIGS. 2 and 3, a fulcrum 7 a is formed at one end 1 b of the opening of the protective tube 1 in which the thermocouple 2 and the pipe 3 are sealed via an insulating material 4. A terminal box 7 having a lid 7b which can be opened and closed by means of is attached, a terminal board 8 is provided therein, and an end 3b of the pipe 3 is provided to reach the terminal board 8, and one end 2b of the thermocouple 2 is connected to the terminal board. 8 is attached to the terminal block 9 with a set screw 10. An external conductor (not shown) extends from the opening 70 of the terminal box 7 to the terminal block 9 and is used for measurement.

In this manner, the thermocouple 2 having the temperature measuring contact at the tip 2a and the pipe 3 having one end 3b are inserted in parallel into the metal protective tube 1 having the tip 1a closed. A sheath-type thermocouple of the present invention obtained by filling the insulating material 4 between the protective tube 1 and the metal protective tube 1 to reduce the diameter thereof is installed on the site and used for temperature measurement. During this measurement, one end 3b of the opening of the pipe 3 is sealed with a plug 11 as necessary to maintain the internal temperature and to prevent heat dissipation to the terminal box 7, thereby reducing the temperature rise of the terminal box 7. prevent.

[0014] Then, when necessary, for example, after using the high temperature for a long period of time, etc., the lid 7b of the terminal box 7 is opened and the plug 1 is opened from one end 3b of the opening of the pipe 3.
Then, a thermocouple 6 having the same material as that of the thermocouple 2, for example, is inserted into the pipe 3 as a reference thermocouple 6 for checking, such as a sheath thermocouple which is compared with a standard or is regarded as a standard. The temperature is measured and compared with the temperature measured by the thermocouple 2. The two thermocouples are provided at substantially symmetrical positions in the metal protective tube 1 and are correctly compared in an actual measurement state in which the temperature distribution in the longitudinal direction is equal and the temperature distribution is equal. If the thermocouple temperature readings are different,
Whether the calibration characteristics of the thermocouple 2 are corrected within a predetermined tolerance,
Alternatively, the degree of deterioration of the thermocouple 2 can be confirmed based on the magnitude of the difference, calibration and life determination can be performed in use, and the replacement time can be accurately known.

[0015]

As described above, according to the present invention, a thermocouple having a temperature measuring contact and a pipe having an open end is inserted into a metal protective tube having a closed end. A thermocouple formed by filling an insulating material between the protective tube and the metal protective tube and reducing the diameter of the protective tube. In this way, with a simple configuration using a protective tube and pipe, there is no need to remove the thermocouple at all, and by inserting a reference thermocouple for checking into the pipe, it can be easily used during temperature measurement on site The degree of deterioration of the thermocouple inside can be confirmed and detected, and the thermocouple can be re-calibrated and the life can be determined according to the actual conditions in use. It is not necessary to replace periodically every time the device is used for a predetermined period of time empirically, so no expensive verification equipment or labor for verification is required, accurate comparison can be performed in actual use, and periodic replacement of thermocouples There is no risk of wasting without exchanging the thermocouples that can be used at the same time. In addition, since the life can be determined by comparing with the reference thermocouple for checking, the replacement time can be accurately understood,
You can continue to use the thermocouple up to the usage limit and limit,
Temperature measurement with required accuracy over a long period of time becomes possible. In addition, since the thermocouple for measurement and the reference thermocouple for checking are located in the protective tube in parallel, the positions of the temperature measuring contacts of both thermocouples are close to each other, and the temperature gradients in the longitudinal direction are equal, and the thermocouples are inserted. There is no influence of the length, and the temperature distribution state is the same, and high-precision comparative temperature measurement can be performed in the performance in the actual use state. The temperature distribution of the thermocouple for measurement and the thermocouple for check in the horizontal direction of the cross section is brought close to each other, and the horizontal cross-sectional position of both in the cross-sectional direction is set to a symmetrical position of almost the same diameter position, so that the temperature distribution is obtained. It can be equal, and can measure with higher accuracy. In addition, since there is an insulating material that is tightly filled between the protective tube and pipe, heat conduction is extremely good and responsiveness is good. The inside of the pipe was sealed and kept warm until then, and the outside air etc. flowed in and did not become low temperature, so that accurate temperature measurement was immediately possible,
The temperature rise of the terminal box can be prevented. It is obvious that a desired effect can be obtained by using a lightly baked insulating material having a predetermined shape in addition to using a powdery insulating material.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a configuration explanatory view showing one embodiment of the present invention.

FIG. 3 is a configuration explanatory view showing one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal protective tube 2 Thermocouple 3 Pipe 4 Insulation material 5 Sealing material 6 Thermocouple 7 Terminal box 8 Terminal board 9 Terminal block 10 Set screw 11 Plug

Claims (1)

[Claims] 1. A thermocouple having a temperature measuring contact and a pipe having an open end is inserted into a metal protection tube having a closed end, and an insulating material is filled between at least the pipe and the metal protection tube. And a thermocouple formed by reducing the diameter of a metal protection tube.