JPS5932903Y2 - Temperature measuring device for thermal noise thermometer - Google Patents

Description

[Detailed description of the invention] The present invention is a thermal noise thermometer temperature measurement device that utilizes the fact that the thermal noise signal (voltage, current, or power) generated in a resistor has a certain relationship with the temperature of this resistor. It is related to.

In thermal noise thermometers, the noise output generated in the resistor is extremely small, so the temperature measuring device must be tightly shielded, but as the temperature rises, the electrical resistance of the insulator decreases, and the The electrical resistance of becomes higher, so
If a current flows from the outside into the shield part, it becomes external noise and causes a measurement error.

For this reason, it is desirable to have a double structure for the shield, but the structure must be such that the temperature of the resistor sealed inside becomes equal to the temperature to be measured within a short time.
There were many problems, such as ■The structure was complicated, and ■The manufacturing was troublesome and expensive.

The present invention relates to a temperature measuring device for a thermal noise thermometer that solves the above-mentioned problems, and will be explained below with reference to the drawings.

The figure is a longitudinal sectional view of an embodiment of the present invention.

In the figure, 10 is a metal protection tube of a commonly used thermometer, 11 is the protection tube body, 12 is a terminal box provided at the top of the protection tube, and 13 is a support plate made of an insulator fixed inside the terminal box. It is.

Reference numeral 21 denotes a temperature measuring element, and a resistor 23 is enclosed in a metal pipe 22 with an insulator interposed therebetween.

24 is a lead wire. Note that this temperature measuring body 21 may be a commercially available sheath type temperature measuring body.

Reference numeral 31 denotes a shield case provided on the support plate 13 in the terminal box 12, and its cylindrical leg portion 32 penetrates the support plate 13 and protrudes downward, and the temperature measuring element 21 is attached to the leg portion 32 vertically. It is inserted so that it can be moved.

The lead wire 24 of the temperature measuring element 21 is connected to a terminal 33 provided on the shield case 31 via an insulator and taken out to the outside.

Further, the metal tube 22 of the temperature measuring body 21 is connected to a terminal 34 provided on the shield case 31 via a lead wire 25 and grounded.

Note that both lead wires 24 and 25 are connected to both terminals 33 and 34 with some margin.

Reference numeral 14 indicates a good heat conduction tube interposed between the protection tube body 11 and the temperature measurement body 21 near the tip of the protection tube body 11 (the part where the resistor 23 in the temperature measurement body 21 is enclosed). A suitable insulator (for example, alumina, ceramic, etc.).

As a result, the resistor 23 and the lead wire 24 are doubly shielded by the protection tube body 11, the terminal box 12, the metal pipe 22 of the temperature sensor, and the shield case 31, and the temperature sensor 21 and the protection tube main body 11 are doubly shielded. is the support plate 13 and the insulator 1
4, it is completely insulated.

Reference numeral 15 denotes a spring interposed between a flange 26 attached to the temperature sensing element 21 and the support plate 13, which presses the lower part of the temperature sensing element 21 against the inside of the insulator 14.

Reference numerals 16 and 17 denote guides made of an insulating material, which facilitate insertion of the temperature sensing element 21 and ensure more reliable insulation between the protection tube main body 11 and the temperature sensing element 21.

As is clear from the above explanation, the present invention uses a commonly used metal protection tube, places a shield case inside the terminal box, and also places a shield case near the resistor part enclosed in the thermometer and the protection tube. Complete 2 by interposing an insulator between the main body and the
It has a heavy shield structure, and is simple in structure and easy to manufacture. Also, the ground current that causes problems is small, and the ingress of external noise is also small.

In addition, since a material with good thermal conductivity is used for the insulator interposed between the protective tube body and the area near the resistor pair of the temperature sensor, the temperature of the resistor is quickly measured with good thermal response. Can be matched with temperature.

Furthermore, since the portion of the temperature sensing element near the resistance pairing part is pressed against the insulator by the pressing means, the temperature sensing element is brought into close contact with the insulator, and the thermal response characteristics are further improved.

In addition, since the insulator is placed only in the necessary areas near the resistor part of the temperature sensor, good thermal response characteristics are maintained, but the insulation characteristics of the insulator itself are reduced due to temperature rise. , it is possible to prevent the insulation properties of the entire device from deteriorating.

Furthermore, since the protection tube and the temperature sensor can be easily separated, inspection and replacement of the temperature sensor is easy.

[Brief explanation of drawings]

The figure is a longitudinal cross-sectional view of an embodiment of the present invention, in which 10 is a metal protection tube;
1 is a protection tube main body, 12 is a terminal box, 14 is an insulator, 21 is a temperature measuring element, 23 is a resistor, and 31 is a shield case.

Claims (2)

[Scope of utility model registration request] (1) Resistance to a metal protection tube whose tip is closed and whose other end opening is covered and shielded by a terminal box made of metal, and a metal tube whose tip is closed and inserted into the metal protection tube with a gap. a temperature sensing element sealed with its body insulated; a shield case provided insulated in the terminal box and covering the other end opening of the temperature sensing element and a lead wire; and a tip portion inside the metal protection tube. an insulator having good thermal conductivity and a U-shaped cross section, which is inserted and fixed and is removably inserted near the resistor enclosing part of the temperature sensor; A temperature measuring device for a thermal noise thermometer, comprising a suppressing means for pressing one end against the insulator. (2) A sound measuring device for a thermal noise thermometer as set forth in claim (1) of the utility model registration, comprising a guiding insulator for a temperature measuring body provided within a metal protection tube.