SU1377615A1 - Method of contactless measurement of temperature of heating of current-conducting body surface - Google Patents

Abstract

This invention relates to thermometry. The purpose of the invention is to increase the sensitivity of the method. The eddy current sensor (HP) 17 forms a voltage depending on the parameters of the object to be measured. The reference voltage from the output of the compensating voltage generating unit 10 is supplied to one input of the phase meter 12, to the other input of which the voltage is supplied from the output of the subtractor 11. This voltage is equal to the voltage difference from the output of the voltage compensation unit 10 and 17 Phase meter 12 measures the phase angle between the reference voltage M coinciding in phase with the current in the sensor power supply circuit and the voltage equal to the voltage difference from the output of the VD 17 and the compensating voltage. At the end of the measurement, a coincidence circuit 15 is activated, which compares the code corresponding to the initial phase angle angle with the code corresponding to the current angle. The signal of this circuit triggers the trigger 4, prohibiting the counting of pulses by the counter 7, and the memory 16 is triggered, in which the temperature values corresponding to the given value of the final frequencies are stored. At the output of the storage device according to the Vits code of the measured temperature. 2 Il. c (C (L

Description

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The invention relates to thermometry and is intended for non-contact measurement of the surface surface heating temperature of conductive bodies.

The purpose of the invention is to increase the sensitivity of the method.

Figure 1 shows the general scheme of the device for implementing the method; on

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Fig. 2 is a block voltage circuit diagram of the com- puter voltage from the output of block 10 is fed to one of the inputs of the phase meter 12, to the second input of which is supplied the voltage from the output of the subtractor 11. This voltage is equal to 15 the voltage difference from the output of block 10 forming a compensating voltage and output of a vicretok sensor 17. The circuit is calculated so that with the initial frequency Wfl of the controlled generator: 9 the compensating voltage is equal to the no-load voltage of the eddy current sensor 17 (i.e. presence of parts). Phase 12 measures the phase angle between the reference voltage coinciding in phase with the current in the sensor supply circuit and the voltage equal to the voltage difference from the output of the eddy current sensor 17 and the compensating voltage. Phase meter 12 is triggered by a pulse from the inverted output of generator 6. The time separation of the beginning of the change in the frequency of the controlled generator 9 and the beginning of the measurement of the phase angle is made so that the transients in the circuit end before the start of the measurement of the phase angle. AT . if the frequency of the controlled oscillator 9 is not equal to the initial frequency CO ;, after measuring the phase angle, the next pulse from the oscillator 6 comes to the input of the binary counter 7. If the current frequency is equal to frequency O (s, the coincidence circuit 14 triggers, according to the signal which register 13 after the phase angle I2 measuring the phase angle (the end of the measurement is indicated by the signal End of measurement from the phase meter output) is written a code proportional to the phase shift needle between the reference and differential voltages at the initial temperature e and the initial frequency of the supply voltage. When triggered, the coincidence circuit 14 is reset to zero trigger 3 thereby inhibit the delivery of pulses to the counter 7.

retirement voltage and eddy current probe.

The device for implementing the method of contactless measurement of the surface heating temperature of the conductive bodies comprises the Set 1 button, the 2 Measurement button, triggers 3 and 4, the OR 5 circuit, a 6 square pulse generator, a binary counter 7, a digital-to-analog converter (id) 8, control sinusoidal voltage generator 9, a compensating voltage generating unit 10, a subtraction device 11, a phase meter 12, a register 13, matching circuits 14 and 15, a programmable single-mode memory (PROM) 16 and an eddy current sensor (B TD) 17.

The eddy current sensor 17 (FIG. 2) consists of an excitation winding 18 and a measuring winding 19. The compensating voltage generating unit IO consists of the excitation winding 20, the measuring winding 21, resistors 22 and 23, and a resistor optocoupler 24.

The invention is implemented as follows.

In the installation mode, the Set 1 button is pressed. In this case, the trigger 3 is set to 1 and through the OR 5 circuit enables the counting of pulses from the direct generator output of 6 square pulses by the binary counter 7. The binary code from the output of the counter 7 is fed to the input of the DAC- 8 and the input of the circuit 14 coincidence. The latter is tuned to a code corresponding to the initial frequency Wg, the D / A converter 8 converts the binary code arriving at its input into an analog signal that controls the frequency of the controlled oscillator 9. The compensating voltage generating unit 10 generates a voltage relative amplitude (amplitude, referred to the amplitude of the idle voltage of the HTS) is inversely proportional to the frequency of the controlled generator 9. Vortex35

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The sensor 17 generates a voltage depending on the parameters of the object to be measured, and the amplitude of the idling voltage at the HTD output depends on the frequency of the controlled generator 9. Block 10 also generates a reference voltage coinciding in phase with the current in the sensor supply circuit. Support3

In the Measurement mode, the temperature of the surface of the conducting body was measured. Before pressing the button Measurement 2, the circuit has the following initial state. Controlled generator 9 has started

The frequency ω ,, is recorded in register 13, which is proportional to the phase shift angle between the current and the differential drop. When the Measurement button is pressed, trigger 4 is set to I allowing pulse counting from generator 6 by a binary counter 7. An increase in the frequency of the controlled generator 9 occurs.

At the end of the measurement, a coincidence circuit 15 is activated, which compares the code corresponding to the initial angle of phase shift with the code corresponding to the current angle. The signal of this circuit triggers the trigger 4, prohibiting the counting of pulses by the counter 7, and the PROM 16 is triggered, in which the temperature values corresponding to a given finite frequency value are stored. In this case, at the output of the EPROM 16 p o is the code of the measured temperature.

The eddy current sensor 1 7 may be configured as an air transformer, where the winding 18 is the primary winding and the winding 19 is. secondary. The voltage across the winding 19 is proportional to the frequency of the supply voltage. The compensating voltage generating unit 10 may be performed, for example, in the form of a through-pass coil with two windings - exciting (primary) 20 and measuring (secondary) 21. Measuring

The winding is connected to a voltage divider consisting of a constant resistor 22 and a resistor optocoupler 24 As the frequency of the supply voltage increases,

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the voltage across the measuring winding 21 increases, however, the input current of the optocoupler 24 also increases, thereby reducing the resistance of the optocoupler resistor. TaKHNt, with an increase in the frequency of the supply voltage, the output voltage module does not change its value. And so, with an increase in the frequency of the supply voltage, the no-load voltage on the measuring winding of the HTD 17 increases, the relative amplitude of the compensating voltage decreases. The reference voltage proportional to the primary current is removed from resistor 23.

Claims (1)

Invention Formula The method of contactless measurement of the temperature of heating of the surface of the conductive bodies, which consists in measuring the angle, phase shift between the eddy current transducer supply current and voltage at the initial temperature and initial frequency of the supply voltage, remembers this angle The frequency of the supply voltage to the equality of the phase angle between the current and the voltage at the new frequency the phase angle at the initial temperature and the initial frequency and the value of the final frequency judge the temperature Surfaces characterized in that, in order to increase sensitivity, when measuring the phase angle, the difference between the output voltage of the eddy current transducer and the compensating voltage generated is used, the relative amplitude of which is inversely proportional to the frequency of the supply voltage. Separate FIG. 2 NP