JP2513892B2 - Temperature sensor for strong magnetic field - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature sensor for a strong magnetic field used in a strong magnetic field cryogenic environment such as a superconducting generator, a linear motor car, and a superconducting electric power storage.

"Prior Art" Resistance temperature detectors such as platinum-cobalt and carbon, and thin film resistance temperature detectors such as thermistor, amorphous-silicon and platinum measure temperature by using temperature dependence of electric resistance. Thermocouples such as gold-iron chromel measure the temperature using the thermoelectromotive force generated by the temperature difference between the temperature-measuring junction between different conductors and the other end. The capacitance-type temperature sensor measures the temperature by using the temperature dependence of the capacitance between two conductor electrodes facing each other with a dielectric interposed therebetween.

The above temperature sensors are industrially useful and widely used, but since they all use the electro-magnetic principle, the movement of electrons and carriers is disturbed by the strong magnetic field in an environment where a strong magnetic field is applied. , The measurement value had an error and could not be used.

An example of the prior art is shown in FIG. FIG. 1 shows a resistance temperature detector sensor. Since it is a three-wire resistance temperature detector, there are three conducting wires 8. Fix the resistance temperature detector 1 and the conductor 8 while insulating them with the insulating powder 2 so that the three resistance wires of the resistance temperature detector 1 and the conductor 8 and the sheath 3 are not short-circuited in the metal sheath 3 such as SUS316. are doing. It is sealed with a sheath sealing portion 4 such as epoxy so as not to absorb moisture in the atmosphere, and the conductor 9 with the coating 10 is connected to the conductor 8.
It is electrically joined with silver solder, etc. to 7 and sleeve 5 such as SUS316.
Then, the sheath 3 and the sleeve 5 are welded 16 with each other, and a resin 6 such as epoxy is filled in the sleeve 5.

The temperature of the resistance temperature detector 1 is measured by being connected to an electric meter through a crimp terminal 11 provided at one end of the lead wire 9.

FIG. 2 is a detailed view of the resistance temperature detector 1. A temperature measuring resistance wire of a coil-shaped platinum wire 14 is passed in a U shape into the holes of two holes 13 made of alumina or the like, and both ends of the insulator 13 are sealed with a ceramic adhesive 12. The platinum wire 14 is connected to the conducting wire 8 such as copper. In order to accurately measure the electric resistance value of the platinum wire 14 by constructing a bridge as an example of an electric meter as a three-wire resistance temperature detector and calculating the temperature, the lead wire 8 is, as shown in FIG. There are 3 branches of C.

[Problems to be Solved by the Invention] When a strong magnetic field H is applied to the resistance temperature detector 1 or the conductor 8 in the resistance temperature sensor 20 having the above-described structure, the strong magnetic field H is generated.
In accordance with the change of the above, an induced current is generated in the platinum wire 14 and the lead wire 8 and causes a large error in the temperature measurement value. Therefore, such a temperature sensor cannot be used under a strong magnetic field.

"Means for Solving the Problems" In the present invention, a metal superconductor such as a niobium alloy, a ceramic superconductor such as ytnium-barium-copper-oxygen system, or a superconductor such as an organic superconductor is reacted at a critical temperature or lower. It is used to exhibit magnetism.

[Example] Fig. 3 shows the diamagnetism of a superconductor due to the Meissner effect. Above the critical temperature T ₀ of the superconductor 30, since the superconductor 30 is not in the superconducting state as shown in FIG. 3A, the magnetic flux 31 is also applied to the internal space 32. However, the critical temperature T ₀
In the following, as shown in FIG. 3B, the superconductor 30 is in a superconducting state and exhibits perfect diamagnetism due to the Meissner effect, so that the external magnetic flux 31 cannot penetrate into the superconductor 30 and the internal space 32. Even if the superconductor 30 'has a small hole 34 as shown in FIG. 3 (c), almost no magnetic flux 31 can enter the internal space 32. Therefore, the temperature sensor body 35 and the conducting wire 36 are put in this space 33. This superconductor 30 ', temperature sensor body 35,
If the conductor 36 is regarded as a temperature sensor as a unit, the temperature sensor 37 will generate a magnetic flux 31 due to the complete diamagnetism of the superconductor 30 'only when measuring the critical temperature T ₀ or lower.
It is possible to configure a temperature sensor that is not applied to the conducting wire 36 and does not cause an error even under a strong magnetic field.

Here, the temperature sensor may be any of a resistance temperature detector, a thermistor, a thin film resistance temperature detector, a thermocouple, an electric capacity type temperature sensor, etc., and the electron / carrier etc. are involved in the principle of temperature measurement. Any temperature sensor affected by a magnetic field can be applied.

Further, when the temperature sensor main body is the only part that is mainly affected by the magnetic field, the periphery of only the temperature sensor main body may be surrounded by the superconductor, and the conductor may not be surrounded. On the contrary, when only the conductive wire portion is mainly affected by the magnetic field, only the peripheral portion of the conductive wire portion may be surrounded by the superconductor and the temperature sensor body may not be surrounded. Generally, only the portion that is easily affected by the magnetic field is surrounded by the superconductor, and the other portions may not be surrounded.

The conventional example is the same as that of FIG. 1, but only the material of the sheath 3 is a niobium alloy superconductor. Therefore, when the temperature of the critical temperature T ₀ is measured by the resistance temperature sensor 20, since the sheath 3 exhibits perfect diamagnetism, even if the strong magnetic field H is applied, the strong magnetic field H is generated inside the sheath 3. Since it does not enter, there is no temperature error due to dielectric current.

 A conventional example is shown in FIG.

Insert the thermocouple 52 with the temperature measuring contact 53 formed in the sheath 51 of the superconductor, fill the gap with insulating powder (MgO) 54, and heat it with annealing if necessary, and then seal with epoxy or the like.
56. The aluminum die cast terminal box 58 is joined to the SUS316 flange 57 at the fitting portion 405. Sheath 51 is flange
Welded 404 with 57. The thermocouple 52 penetrating the hole 406 of the ceramics terminal plate 60 is screwed by the terminals 62 and 63,
Is fixed to the terminal box 58 with screws 61 and 64. The compensating conductor 65 of the cable 68 screwed with the bellmouth 400 through the ring 401/402 and the packing 403 at the wire hole 66 is the terminal 62/63
Is connected to thermocouple 52. Aluminum die cast lid 59
Is fitted to the terminal box 58 at the fitting portion 69. The B section of the compensating lead wire 65 is connected to an electric meter.

The thermoelectromotive force V corresponding to the temperature difference between the temperature measuring contact 53 and the B portion of the compensating lead wire 65 is output to the B portion, but the sheath 51 exhibits complete diamagnetism when measuring below the critical temperature. Therefore, the external magnetic field H cannot enter the thermocouple 52 and the temperature measuring contact 53, and no measurement error occurs.

 An embodiment of the present invention is shown in FIG.

4-wire resistance temperature detector 101 and conducting wire in SUS316 sheath 105
106 is inserted, the gap is filled with MgO insulating powder 102, and the sheath sealing portion 108 is sealed with epoxy. It further SUS31
6 Insert into the sheath 104, and insert ceramic superconductor powder in the gap.
103 is filled, and the sheath sealing portion 107 seals the sheath with epoxy. A conductive wire 113 having a coating 112 is joined to the conductive wire 106.
09, the joint 109 part is covered with the sleeve 114, the sleeve 11
The distal end of the sleeve 4 is externally fitted to the proximal end of the sheath 104 and fixed by welding 110, and the sleeve 114 is filled with the resin 111.

When measuring below the critical temperature, the superconducting powder 103 exhibits perfect diamagnetism and the external magnetic field H cannot penetrate into the resistance temperature detector 101, so that no measurement error occurs.

 A conventional example is shown in FIG.

A 4-wire resistance temperature detector 75 is inserted in a case 72 of a superconductor, He gas 74 for improving heat transfer is filled, and then a conductor 73 is resin-sealed 71 with epoxy. The principle that the external magnetic field H is not applied to the resistance temperature detector 75 due to the complete diamagnetism of the case 72 is the same.

 A conventional example is shown in FIG.

A film 80 of a superconductor is formed on the side surface of a two-hole insulator 81 made of an insulating material such as ceramics by a method such as vapor deposition, sputtering or thermal spraying. A thermocouple 82 is inserted into the two holes of the insulator 81, and a temperature measuring contact 83 is formed on the outside of the insulator 81.

The magnetic field H is a thermocouple due to the complete diamagnetism of the superconductor film 80.
Since it is hardly applied to 82, no measurement error occurs.

 A conventional example is shown in FIG.

The structure of the resistance thermometer 310 is almost the same as in FIG. 2, but the side surface of the two-hole insulator 302 is covered with the cylinder of the superconductor 301, and the lid 304 of the superconductor is made of two holes with the ceramic adhesive 305. The difference is that it is adhered to the insulator 302. Due to the complete diamagnetism of the superconducting cylinder 301 and the superconducting lid 304, the magnetic field H is reduced by the platinum wire 303.
Since it is applied to, there is no measurement error.

 A conventional example is shown in FIG.

The thin film resistance temperature detector 403 and the lead wire 406 are sandwiched between insulating flexible substrates 401 and 402 made of resin, and the substrates 401 and 402 are sandwiched between cases 404 and 405 of superconductor. The case 404 and the case 405 are fixed to each other with an adhesive or the like. Superconductor case 404.4
Due to the perfect diamagnetism of 05, the external magnetic field H is 40
3 and the conductor 406 are not applied, no measurement error occurs.

[Advantages of the Invention] As described above, according to the present invention, since the required portion of the temperature sensor is made of a superconductor, the magnetic field is not applied to the temperature sensor even if an external magnetic field is applied, and a measurement error does not occur.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a conventional resistance temperature detector sensor, FIG. 2 is a detailed side view of the resistance temperature detector, FIG. 3 is a view for explaining the relationship between a superconductor and a magnetic field, and FIG. 4 is a conventional example. 5 is a vertical sectional view of a thermocouple, FIG. 5 is a vertical sectional view of a 4-wire resistance temperature detector showing an embodiment of the present invention, and FIG. 6 is a vertical section of a 4-wire resistance temperature detector showing a conventional example. 8 and 9 are longitudinal sectional views of a thermocouple showing a conventional example.
FIG. 9 is a side view of a conventional resistance temperature detector, and FIG. 9 is a vertical sectional view of a conventional thin film resistance temperature detector.

Claims (1)

(57) [Claims] 1. A metal sheath 105 in which a temperature sensor and a conductor 106 are inserted into a metal sheath 105 whose one end is sealed by a sealing portion 108.
A sheath-type temperature sensor in which the inner space is filled with insulating powder 102, and another metal sheath 104 having one end sealed with a sealing portion 107
A temperature sensor for a strong magnetic field, which is inserted into a metal sheath 104 and filled with a superconducting powder 103 in a gap in a metal sheath 104.