SU838425A1 - Temperature gage - Google Patents

Description

(54) DEVICE FOR TEMPERATURE MEASUREMENT

The invention relates to thermometry and can be used to control the parameters of high-temperature gas flows. A device for measuring temperature is known, which contains an ultrasonic emitter and receiver, mechanically connected to the transfer system and connected to the measuring unit U1. However, this device does not provide the required measurement accuracy due to the error due to the nonidentity of the transducer displacement nodes, the transducers themselves, and the phase characteristics of the amplifiers. The closest to the technical essence of the present invention is a temperature measuring device containing an ultrasonic emitter and receiver mechanically connected with a displacement system connected to the output of the signal conditioning circuit of a measuring unit connected to the inputs of the receiver and emitter 21. However, this device does not have gives the required measurement accuracy because the measurement unit connected to the piezoelectric transducer, emitter and receiver significantly affects the operation of the allocation unit, CONNECTIONS to the same transducer and m having a very high input impedance (R. 10 ° ohms) necessary for measuring the electrostatic potential on the plates of the transducers. In such measurements, the electrical isolation of the measuring circuits has a significant effect. In addition, the electrostatic potential on the plates of piezotransducers depends not only on the absolute temperature of the transducers, but also on the rate of increase in temperature. The faster the temperature of heating of the piezotransducer increases, the higher the potential on the plates and vice versa, although the absolute temperatures may be the same, which leads to errors in determining the heating temperature of the measured object. The aim of the invention is to improve the measurement accuracy. The goal is achieved by introducing a oscillating frequency generator, a trigger, pulse generators, an OR circuit, signal extraction units, to the inputs of which

the outputs of the oscillating frequency generator and the measuring unit, the second output of which is connected to the input of the oscillating frequency generator, are connected to the trigger inputs, to the third inputs of the signal extractor and the generator of pulses connected to the inputs of the signal conditioning circuit, the third input of which is connected to the trigger output connected also to the second input of the oscillating frequency generator, and the output of one signal extractor is connected to the input of the radiator and another block to the input of the receiver, while the second outputs of these blocks s are connected through an OR gate .ko second input trigger.

In addition, each selection signaling unit contains a switch, a detector, a differentiator and a trigger connected in series, the output of which is connected to the second input of the block, and the input of the trigger is connected to the third input of the selection signaling unit, the inputs of the switch are connected to the first and second inputs which is connected to the first output unit.

In FIG. 1 shows a block diagram of the device; in fig. 2 time oscillograms and -Z5).

The device contains an ultrasonic emitter 1, a receiver 2, a system, 3 movements of the emitter and receiver, a measurement unit 4, a signal shaping circuit 5 for the displacement system, a sweep frequency generator 6, an OR circuit 7, a trigger 8, pulse generators 9 and 10 , the switch 11 detector 12, the differentiator 13, the trigger 14 of the signal extraction unit, the blocks 15 and 16 of the signal extraction.

The device works as follows.

At the initial moment of time (Fig. 2). after switching on the power supply of the device, the transducers are introduced into the medium under study and the measurement unit 4 generates a signal pulse (P), which is transmitted by the transducer 1, into the medium under study and is received by the transducer 2. The pulse received by the transceiver 2 transmits to the measurement unit 4, the temperature and velocity of the gas stream is calculated. After the next measurement cycle, the heating temperature of the transducers 1 and 2 is checked.

The temperature control of the transducers is controlled as follows. The measurement unit is triggered by a switch 11 signals, a oscillating frequency oscillator (GCU), triggers 8 and 14, and generators 9 and 10 pulses. GCCH 6 generates a sinusoidal signal, the frequency of which, for some time, time t, (18) becomes equal to the resonant frequency of the less heated transducer, and then at time t (19) and the resonant frequency of the more heated piezoelectric transducer. With an increase in the heating temperature, the resonant frequencies of the piezo transducers 1 and 2 increase. Since the booster switch b through switch 11 is connected to the piezoelectric transducer 1, the detector 12 selects the envelope of this signal. When the oscillator frequency is oscillating, the frequency passes through the resonance of the converter, the output voltage of the detector 12 is the maximum voltage, which is differentiated by the differentiator 13 and returns trigger 14 to the initial state. From the trigger output 14, a pulse of duration i, (18) goes to the OR circuit 7. Similarly, the second signal extracting unit 16 operates. A pulse from the output of this block arrives at the second input of the circuit OR 7. From the output of the circuit OR 7, a rectangular pulse of the longest duration, corresponding to the period of time required for the frequency of the sweep to change from the initial (time t) to the resonant frequency of the most heated converter (in this case, up to the resonant frequency of the piezo receiver 2), goes to the second input of the first trigger 8 and puts it in the initial state at the falling edge. The first trigger 8 with its pulse 21 brings the measurement unit 4 to the initial state and the oscillating frequency generator b-. In the I / O signal generation circuit 5, the pulse duration from the output of the first flip-flop 8 is compared with the pulses from the first and second generators 9 and 10 of the pulses. The first generator 9 pulses produces pulses, the duration of which

. corresponds to the period of time necessary for measuring the frequency of the GCh b to the resonant frequency of the transducers at the highest permissible heating temperature.

The temperature of piezoelectric transducers must be less than the Curie temperature T of the applied piezomaterial. For example, for ceramic PZTZ-19 piezo material T 290 ° C, for quartz-570 ° C, for lithium niobate L i NbOn., L9lO ° C

The second pulse generator 10 produces pulses 24, the duration of which corresponds to the time period t ,, - trj, necessary to change the frequency of the hopper to the resonant frequency of piezoelectric transducers when their heating temperature does not exceed a predetermined value and they can work in the high-temperature medium under study. If the pulse duration arriving at the I / O signal shaping circuit 5 from the first trigger 8 is longer than the pulse width from the first pulse generator 9, the I / O signal shaping circuit 5 issues a command 25 about outputting piezo transducers from the medium under study .. And, conversely, if the pulse duration from the first trigger 8 to the I / O signal shaping circuit 5 is less than the pulse width from the first pulse generator 9, then the converters 1 and 2 are supported in the entered state. If the pulse duration arriving at the I / O signal shaping circuit 5 from the first trigger 8 is less than the pulse width of the second pulse generator 10, then the converters 1 and 2 are maintained in the input state if they were introduced into the test medium earlier or when they were in the selected state 25. When the transducers are introduced into the medium under study, the measuring unit measures the ultrasound velocity and after each measurement cycle checks the heating of the piezo transducers to the moment when the temperature of Lee heated converter reaches a predetermined maximum value. After that, the I / O system 3 from the I / O signal shaping circuit 5 receives a command to output piezoelectric transducers from the high-temperature environment. When the transducers cool down to a predetermined temperature, the signal generation circuit 5 issues a command to the I / O system. inserting piezoelectric transducers into the medium under study, after which the npoiiecc measurement is repeated.

The proposed device, along with an increase in the accuracy of measurement, makes it possible to increase the reliability of monitoring high-temperature environments by controlling the input-output system of ultrasonic transducers into the test medium automatically by the temperature of the most heated transducer. In addition, it makes it possible to automate ultrasound systems for monitoring high-temperature environments, based on determining the speed of ultrasound in controlled environments, and expands the scope of application of ultrasound-measuring systems.

Claims (2)

1. A temperature measuring device containing ultrasonic transducers - emitter and receiver mechanically connected to a displacement system connected to the output of the signal conditioning circuit, a measurement unit connected to the inputs of the receiver and the radiator, so that, in order to a increase in the accuracy of measurement, the oscillating frequency generator, the trigger, the pulse generators, the OR circuit, the signal extraction units, the inputs to which are connected, are entered into the device 5 outputs of the oscillating frequency generator and the measuring unit, the second output of which is connected to the input of the oscillating frequency generator, to the trigger inputs, to the third inputs of the signal isolating units and pulse generators, 0 connected to the inputs of the signal conditioning circuit, the third input of which is connected to the output of the trigger, also connected to the second input of the oscillating frequency generator, and the output 5 of one signal extraction unit is connected to the input of the radiator, and another unit - to the receiver input, while the second outputs of these blocks are connected via the OR circuit to the second input of the trigger. 2. The device according to claim 1, characterized in that each signal extraction unit comprises a switch connected in series, 5 a detector, a differentiator and a trigger, the output of which is connected to the second output of the block, and the input of the trigger is connected to the third input of the signal extractor, to the first and second input of which the inputs of the switch are connected, the output of which is connected to the first output of the block. Information sources. Considered in the examination five 1. Bovsheverov V.M. et al. Acoustic thermometer-interferometer for measuring temperature in the stratosphere. Physics of the Atmosphere and the Ocean, 1969.4, No. 10. 0 2. USSR author's certificate on application 2670089, cl. G 01 K 11/24, 05.10.78 (prototype),  Phie.1