JPH0124602Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an isothermal plate effective for terminal temperature measurement, and more specifically, to provide an isothermal plate effective for reference junction compensation in temperature measurement using a thermocouple.

In process control systems, thermocouples are often used to measure temperature. In temperature measurement using such a thermocouple, the temperature at the measurement point is determined by using the temperature at the terminal portion of the thermocouple as the cold junction temperature. By the way, the terminals of such thermocouples are generally screwed to the terminal board. Therefore, when measuring the temperature of the terminal portion of a thermocouple, it is desirable to measure the temperature with the terminal portion of the thermocouple screwed in the same manner as the terminal portion of the thermocouple.

FIG. 1 is a perspective view showing an example of a conventional temperature measurement unit that focuses on such points, and 10 is a case containing a printed wiring board in which circuit components including a transistor temperature sensor are arranged, and 20 is a case containing a printed wiring board on which circuit components including a transistor temperature sensor are arranged. One end is formed with a notch that fits into the mounting screw of the terminal, and the other end is a mounting piece made of a good thermal conductor that is inserted and fixed into the case and is thermally coupled to the temperature sensor. 30 is a wiring cable. .

According to such a configuration, the temperature can be measured while being fixed to the terminal screw of the terminal board. However, such temperature measurement units are configured to measure temperature using the temperature characteristics of the transistor's V _BE , which results in variations in characteristics for each temperature sensor and requires a complex signal processing circuit. It has the disadvantage of becoming A two-wire temperature sensor that solves these drawbacks is configured to output a current expressed as I _t = (t + 273.15) (μA) when a 6V power supply is applied at a temperature of t°C.
IC temperature sensors have been put into practical use. However,
This IC temperature sensor generates a relatively large amount of self-heating compared to a conventional transistor temperature sensor, and if it is incorporated into a temperature measurement unit as shown in FIG. 1, there is a risk of measurement errors due to self-heating.

When using such an IC temperature sensor,
What is necessary is to improve the heat dissipation of the temperature sensor and the heat transfer with the object to be measured. FIG. 2 is a perspective view showing an example of a temperature measurement unit that focuses on these points, and 40 is a 2-wire unit that outputs a current related to the measured temperature.
A case made of a thermal insulator that houses a printed wiring board on which circuit components including a wire type IC temperature sensor are arranged, and a heat transfer body fitted around the outer periphery of the temperature sensor;
Reference numeral 50 denotes a mounting body made of a thermally conductive material installed in the case 40 so as to be thermally coupled with the heat transfer body housed in the case 40, and 60 a thermal insulator installed on the upper surface of the case 40. 70 is a wiring cable. In such a temperature measurement unit, the mounting body 50 is provided with an L-shaped bent piece 51 for holding the temperature measurement object. When attaching the temperature measuring unit to a terminal board partitioned by a partition wall, use these bent pieces 5.
1 to sandwich the partition wall.

However, in order to thermally connect such a temperature measuring unit to a terminal, some kind of relay must be interposed.

The present invention realizes an isothermal plate that is effective as such a relay body, and includes a first mounting piece for screwing to a terminal to be measured through an insulating bushing, and a terminal to be measured by a screw. A second mounting piece for direct screwing to the temperature sensor and a mounting surface to which the mounting body of the temperature measurement unit, which is thermally coupled to the temperature sensor, is mechanically and thermally removably coupled are integrated with a good thermal conductor. characterized in that the first mounting piece is provided with a stepped portion so that the mounting surface to the terminal with the insulating bushing attached is equal to the mounting surface of the second mounting piece. .

Hereinafter, it will be explained in detail using the drawings.

FIG. 3 is a configuration explanatory diagram showing one embodiment of the present invention, in which 80 is an isothermal plate according to the present invention, and 90 is an insulating bush. The isothermal plate 80 is made of a good thermal conductor such as phosphor bronze, and the mounting pieces 81 and 82 for screwing to the terminal of the temperature measurement object and the mounting body 50 of the temperature measurement unit are mechanically and thermally A mounting surface 83 that is removably coupled, a bending piece 84 for regulating the coupling position of the temperature measuring unit, and the like are integrated. The insulating bushing 90 is for electrically insulating between the terminals when the isothermal plate 80 is attached to the terminals, and is fitted into the mounting piece 81. Note that the mounting piece 81 is provided with a stepped portion so that the mounting surface to the terminal with the insulating bushing 90 attached is equal to the mounting piece 82.

FIG. 4 is a configuration explanatory diagram showing an example of mounting the isothermal plate 80 according to the present invention.
1 is attached to a terminal plate 100 of a temperature converter. The mounting piece 81 of the isothermal plate 80 is connected to the mV check terminal 101 via the insulating bushing 90.
The mounting piece 82 is screwed together with the thermocouple to the + input terminal 102 of the thermocouple. The temperature measuring unit is mounted on the isothermal plate 80 by sandwiching the mounting surface 83 of the isothermal plate 80 between the mounting pieces 51 of the mounting body 50.
It is removably attached to 0. Thereby, the terminal 102 and the temperature sensor of the temperature measuring unit are thermally coupled via the isothermal plate 80 and the mounting body 50. That is, the heat of the terminal 102 is transferred to the isothermal plate 80.
The heat generated by the temperature sensor is transmitted to the temperature sensor via the mounting body 50, and the heat generated by the temperature sensor is radiated via the mounting body 50 and the isothermal plate 80. As a result, isothermal plate 8
At 0, heat is transferred and received, and the temperature sensor and the terminal 102 are almost at the same temperature.

According to such a configuration, the isothermal plate 80 acts as a heat sink of the temperature sensor and increases the heat capacity of the terminal 102, so that stability against fluctuations in outside temperature can be improved. Further, according to the present embodiment, the terminal 101 which is not normally used
Since the mounting piece 81 of the isothermal plate 80 is attached to the isothermal plate 80, the isothermal plate 80 will not fall off even if the thermocouple input terminal screw is removed when attaching or removing the thermocouple.
Thermocouple attachment/detachment work can be performed without being aware of the isothermal plate 80. Further, according to this embodiment, even when the isothermal plate 80 is attached, the terminals 101 and 102
Since it is electrically insulated, mV checking can be performed as needed with the temperature measuring unit attached.

Note that in order to more accurately measure temperature with a thermocouple, it is desirable to make the + terminal and the - terminal strictly equal in temperature. In that case, it is sufficient to thermally couple the + terminal and the - terminal while electrically insulating them using an isothermal plate.

Further, in the above embodiment, an example is shown in which an IC temperature sensor with a relatively large calorific value is used as the temperature sensor, but a transistor temperature sensor may also be used.

As explained above, according to the present invention, an isothermal plate effective for terminal temperature measurement can be realized, and is suitable for reference junction compensation in temperature measurement using a thermocouple.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a conventional temperature measuring unit, Fig. 2 is a perspective view showing an example of an improved temperature measuring unit, and Fig. 3 is a configuration explanatory diagram showing an embodiment of the present invention. FIG. 4 is an explanatory diagram of an example of mounting the isothermal plate according to the present invention. 80... Isothermal plate, 81, 82... Mounting piece, 83
... Mounting surface, 84 ... Bending piece, 90 ... Insulating bushing, 100 ... Terminal board, 101 ... mV check terminal, 102, 103 ... Thermocouple connection terminal.

Claims (1)

[Claims for Utility Model Registration] A first mounting piece for screwing to a terminal to be measured through an insulating bushing, a second mounting piece for directly screwing to a terminal to be measured for temperature, The temperature sensor and the mounting surface to which the mounting body of the temperature measurement unit thermally coupled is mechanically and thermally detachably coupled are integrated with a good thermal conductor, and the first mounting piece is provided with an insulating bushing. An isothermal plate for terminal temperature measurement, characterized in that a stepped portion is provided so that the mounting surface to the terminal in the attached state is equal to the mounting surface of the second mounting piece.