SU1448222A1 - Device for measuring temperature difference - Google Patents

Abstract

The invention relates to a measurement technique, namely to a means of measuring temperature. The goal is to increase the measurement accuracy under the conditions of exposure to electromagnetic fields, as well as to expand the range of measurement of the temperature difference. The signal proportional to the temperature from thermistors 1,2, from the output of the electric bridge 3 goes to the differential amplifier 4 and further to two thermoelectric thermopile 8, 7, located in the thermostat 9 with a radiator. Heat energy from thermoelectric batteries is supplied to a temperature-sensitive piezoelectric resonator 10 located between them, connected to the input of the generator 11, the output of which is connected to the measuring unit 12. 2 Il. (L

Description

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The invention relates to a measurement technique, namely to temperature measurement means, and may find application in the engineering, aviation, shipbuilding, electronic and chemical industries.

The purpose of the invention is to improve the accuracy of measurement under the influence of electromagnetic fields, as well as expanding the range of measurement of the temperature difference,

Figure 1 is a diagram of a device for measuring temperature differences; FIG. 2 shows a thermostat design.

The device for measuring the temperature difference contains thermistors 1, 2j differentially included in the shoulders of an electric bridge 3, a differential amplifier 4, made on transistors 5 and 6, two solid-state thermoelectric microbatories 7 and 8, a thermostat 9, a temperature-sensitive piezoelectric resonator 10, a generator 11 and measuring unit 12, Elements 7-11 form a pre-generator of the difference of electrical signals at frequency 13. Thermostat 9 has shells 14 and 15 of heat insulating material, as well as a radiator, 16.

The device works as follows.

With equal temperatures of objects controlled by thermistors 1 and 2, the resistance of thermistors is equal. The potential difference at the measuring diagonal of bridge 3 is zero. Through thermoelectric microbatteries 7 and 8, connected to the symmetrical outputs of the differential amplifier 4, initial currents flow, which are set when the device is tuned and allow the temperature TQ 5 to be maintained in the working chamber of the thermostat 9 corresponding to the down / left temperature difference.

If there is a temperature difference of any sign, the difference in potentials at the points of the measuring diagonal of bridge 3 is different from zero. A control voltage is applied to the inputs of the differential amplifier 4. The currents corresponding to the control voltage flow through the microbatteries 7 and 8. The working chamber of the thermostat 9 is set to a temperature that is different from

with

ten

15

20 25 30

35

40

0

temperature tq. The heat insulating oboles 14 at the same time separates the corresponding junctions of thermoelectric microbatories 7 and 8,

To maintain an approximately constant junction temperature of the microbatches 7 and 8, located outside the shell 14, the latter are placed on the radiator 16, which also plays the role of an electromagnetic shield, reducing its effect of interference. The overall thermal stability of thermostat 9 is provided by a heat insulating sheath 15. A change in temperature inside the working chamber of thermostat 9 leads to a change in the frequency properties of the resonator 10, which in turn causes a change in the frequency of the generator 11, which is recorded by the measuring unit 12,

For example, when the temperature of an object controlled by thermistor 1 increases, the base potential of transistor 6 increases. This increases the current of transistor 6 flowing through the hot junctions of thermoelectric microbattery 8. At the same time, the blocking voltage on the emitter of transistor 5 increases, which leads to a decrease in current transistor flowing through; cold junctions of thermoelectric microbattery 7,

As a result of this redistribution of the currents flowing through the thermoelectric microbatteries 7 and 8, the temperature in the working chamber of the thermostat 9 increases, which leads to an increase in the natural frequency of the thermosensitive piezoelectric resonator 10, and consequently, to an increase in the frequency of the generator signal 11,

In the case when the temperature of the object controlled by thermistor 2 exceeds the temperature of the object controlled by thermistor 15, the potential of the base of transistor 5 increases, the current of transistor 5 increases and the current of transistor 6 decreases, which leads to a decrease in temperature in the working chamber of thermostat 6 and reducing the frequency of the output signal of the generator 11,

Thus, the temperature in the working chamber of the thermottate 9 varies in accordance with the change in the temperature difference of the controlled objects.

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Claims (1)

Claim A device for measuring the temperature difference, containing two thermistors included in adjacent shoulders of the electric bridge, a differential amplifier, the exits of which are connected to the measuring diagonal of the bridge, a converter of the difference of electric signals to frequency and a measuring unit, characterized in that, in order to increase accuracy ₂ q measurements under conditions of exposure to electromagnetic fields and expanding the range of measurement of the temperature difference, the converter of the difference of electric signals to frequency is made in the form of a sensitive piezoelectric resonator, first and second thermoelectric microbatteries, a thermostat with a radiator and a generator, the first and second thermoelectric microbatteries connected to the symmetric outputs of the differential amplifier, the thermosensitive piezoelectric resonator connected to the generator, the output of which is connected to the measuring unit, while the thermosensitive piezoelectric resonator the working chamber of the thermostat between the alternately hot junctions of the first and ho boat junctions of the second thermoelectric microbatteries, and cold junctions of the first and hot junctions of the second thermoelectric microbatteries are located on the radiator. Fig g