JPS5831080Y2 - thermometer calibration device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a thermometer calibration device using a thermocouple as a temperature detection element.

To calibrate a thermometer that uses a thermocouple as the temperature detection element, it is preferable to attach the thermocouple to the thermometer body and apply the actual temperature to the thermocouple. The thermometer body is calibrated as a voltmeter separately from the thermocouple.

The main body of a thermometer that uses a thermocouple as a temperature detection element is composed of a voltmeter section that measures the thermocouple electromotive force, and a reference junction compensation circuit section that compensates for the reference junction temperature.

To calibrate the thermometer body, as mentioned above, it is possible to consider the thermometer body as a voltmeter and apply the voltage obtained from the thermoelectromotive force of the thermocouple to the thermometer body. As the thermometer body has a reference junction compensation circuit, if the voltage obtained from the thermoelectromotive force is applied to the thermometer body, the calibration will be calibrated with an error equal to the voltage generated by the reference junction compensation circuit. It turns out.

Therefore, in order to calibrate the thermometer body, the reference junction compensation circuit section is separated from the voltmeter section, and the voltmeter section and the reference junction compensation circuit section are adjusted and calibrated separately. It is troublesome to do so.

Furthermore, the reference junction compensation circuit cannot be separated from the voltmeter part of the thermometer body, but such thermometers require means for adjusting and calibrating the thermometer body including the reference junction compensation circuit. The reality is that there is no such thing.

The present invention was developed in consideration of these points, and by using a calibrated thermocouple, an isothermal block cable, and a reference temperature bath, it is possible to apply a voltage equivalent to applying the actual temperature to the thermocouple to be calibrated. The thermometer can be calibrated by adding it to the main body of the thermometer, and is characterized in that it can be calibrated very accurately in its housing 1 without having to separate the voltmeter section and the reference junction compensation circuit section.

The figure is a block diagram showing one embodiment of the device of the present invention.

In the figure, 10 is a calibration device according to the present invention) 60 is a thermocouple main body to be calibrated, and this main body is composed of a voltmeter section and a reference junction compensation circuit section.

In the calibration device 10, 20 is a reference temperature tank, and 30 is a calibrated reference thermocouple, which are arranged in the temperature tank 20.

40 is an isothermal block having connections 41 and 42, and 50 is a standard voltage generator that generates a variable standard voltage.

One strand (or compensating lead wire) 31 of the reference thermocouple 30 is connected to one input terminal 61 of the instrument body 60 to be calibrated, and the other strand (or compensating lead wire) 32 is connected to the connecting portion 41 . 42 to the other input terminal 62 of the instrument 60 to be calibrated.

The standard voltage generator 50 is connected to the connection 4L42 of the isothermal block 40 via a conductive wire 5L52.

The conductor wires 51 and 52 are connected to the thermocouple wire 32 at the connecting portions 41 and 42, but the conductor wire 5L52 is of a type that does not generate a thermoelectromotive force between it and the thermocouple wire. The temperatures of the connections @41 and 42 are such that there is no difference in temperature due to the isothermal block 40.

In the device of the present invention having such a configuration, the temperature of the reference temperature tank 20 is set to T1, the temperature of the input terminals 61 and 62 of the calibration thermometer body 60 is set to T2, and the standard voltage generator 5 is set to T1.
0 output voltage is Vs, the voltage Vj input to the thermometer body 60 is Vi = Vemf (T1) - Vemf (T2) + Vs
(1).

Here, Vcmf (T): When the reference junction temperature at temperature T is 0°C, the thermoelectromotive force of the thermocouple used The reference junction compensation circuit arranged in the thermometer body 60 responds to the terminal temperature T2. generates a voltage.

If that voltage is Vc, the electric EVoO value displayed on the thermometer body 60 is Vo = Vi + Vc (2)
Since Vemf(T2)=Vc, equation (2) is Vo
=Vemf (Tt) +Vs (3).

Therefore, if the temperature T1 of the reference temperature tank 20 is, for example, 0°C, v o = Vs (4)
The displayed voltage Vo corresponds to the output voltage Vs of the standard voltage generator 50.

Therefore, by setting the vsO value according to the thermoelectromotive force table of the thermocouple used in the thermometer body 60 to be calibrated, the reference junction compensation circuit portion and the voltmeter portion disposed within the thermometer body 60 can be separated. Temperature calibration can be performed in the same way as temperature calibration using the actual temperature without having to calibrate the temperature.

The reference temperature tank 20 does not necessarily have to be kept at 0°C, and the temperature of the reference temperature tank 20 can be set arbitrarily by subtracting the thermoelectromotive force of the reference thermocouple 30 from the output Vs of the standard voltage generator 50. Can be set.

As explained above, according to the present invention, by using a reference thermocouple, an isothermal block, and a reference temperature bath, the temperature of the thermometer to be calibrated can be adjusted to the actual temperature without separating the voltmeter part and the reference junction compensation circuit part. A device that can calibrate the temperature of the thermometer body with high accuracy under almost the same conditions can be realized with an extremely simple configuration.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the device of the present invention. 10... Calibration device, 20... Reference temperature tank, 30...
・Reference thermocouple, 40... Isothermal block, 50... Standard voltage generator, 60... Thermometer body to be calibrated.

Claims (1)

[Scope of utility model registration request] A reference thermocouple disposed in a reference temperature chamber and calibrated, a standard voltage generator capable of generating a voltage according to an electromotive force table of the thermocouple, and an isothermal block having a pair of connections, Connect the 1'J cable wire (or compensation lead wire) of the reference thermocouple to one input terminal of the thermometer body to be calibrated, and connect the other wire (or compensation lead wire) to the pair of connections of the isothermal block. A thermometer calibration device comprising: a conductor connected to the other input end of the thermometer body to be calibrated via the isothermal block, and a conductor for taking out the output of the standard voltage generator, connected to the connection part of the isothermal block.