SU1483251A1 - Ultrasonic phase meter of vibration movements - Google Patents

Abstract

The invention relates to a measurement technique, in particular to vibrometry, and can be used in various fields of mechanical engineering and instrumentation. The aim of the invention is to improve the measurement accuracy. The device operates in two modes. In the first mode, the main radiating transducer is installed relative to the additional radiating transducer, made in the form of a ring, inside which the main radiating transducer is placed concentrically with it, according to the criterion of the minimal influence of the side lobes of the transducer radiation patterns. In the second mode, the vibration displacement of the monitored object is measured by the phase method. 1 il.

Description

The invention relates to a measurement technique, in particular to vibrometry, and can be used in various fields of engineering and instrument making.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows a structural diagram of the ultrasonic phase meter vibration displacement.

The device contains a series-connected master oscillator 1, a delay line 2 and a main radiating transducer 3 interacting with the object under study 4, a serially connected receiving transducer 5, a phase detector 6, an And 7 element and an analog-to-digital converter 8 and an information processing unit 9. The output of the phase detector 6 through the element And 7 is connected to the input of the comparator 10, the output of which is connected to the input of the switch 11 and the second input of the block 9 of information processing. The other inputs of the comparator 10 are connected to the outputs of the source 12 of the reference voltage. The outputs of the switch 11 are connected to the control inputs of the delay line 2. The output of the receiving converter 5 is connected to the series-connected element 13 and the integrator 14, the analog-digital converter 15, the switch 16, the code comparison circuit 17, the control trigger 18, the clock generator 19, the control unit 20 of the stepping motor, the step motor 21, the converter 22 angle-linear displacement, which is kinematically connected with additional radiating preCO

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the generator 23, made in the form of a ring, inside which is placed the main radiating transducer 3.

The device works in two modes.

In the first mode, the device operates as follows.

The output signal of the master oscillator 1 through the delay line 2 is fed simultaneously to the main and additional radiating transducers 3 and 23. The latter is designed as a concentric ring covering the main transducer 3 and electrically connected with it. In the absence of the object under study 4, the reflected signal at the input of the receiving transducer 5 is absent. However, due to the presence of lateral components of the transducers 3 and 5, the main harmonic signal is induced at the receiving transducer 5, which makes a significant error in measuring , because of this, an error occurs in the selection of the operating point. The acoustic signal received by converter 5 goes through AND 13 to integrator 14 AND Element 13 is in the open state as long as at its second input there is a logical unit signal of the direct (single) output of control trigger 18. In the integrator 14 is the integration of the power of the sinusoidal signal from the receiving transducer. The integrator output signal is proportional to the power received by the receiving signal converter 5.

The electrical signal from the receiving transducer 5 is also fed to the first input of the phase detector 6, the second input of which receives the reference signal from the output of the delay line 2. In order to prevent the output signal of the phase detector 6 from passing to the comparator 10 and, thus, to prevent the delay signal of the reference signal from changing at this stage of the meter operation, the second input of the And 7 element receives the inhibitory signal of the logical zero from the inverted input of the control trigger 18. The integrated analog signal is further converted into an analog-to-digital converter 15 into a digital code. Then, the digital code values corresponding to the two nearest analog signal values are divided into two channels by the switch 16 and are alternately transmitted to the first and second inputs of the code comparison circuit 17. The algorithm of the operation of the code comparison circuit 17 is selected such that at its output the signal of a logical unit is scanned when the value of the digital code recorded on the second channel exceeds the value of the previous digital code recorded on the first channel.

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 The choice of such an algorithm is based on the fact that while the emitted acoustic signals of the main radiating transducer 3 and the additional transducer 23, made in the form of a ring, are in phase, or, equivalently, their radiating surfaces are located in the same plane, the analog signal at the output receiving transducer 5 has a maximum value.

The condition of arranging the radiating surfaces in one plane before the start of work is necessary. If there is a displacement of the plane of the additional radiating transducer 23 relative to the main one in any direction between the ultrasonic signals emitted by the main and additional transducers, a phase mismatch appears, which increases with further movement. At the same time, the ultrasonic signal of the additional transducer 23 begins to weaken the influence of the side lobes of the main transducer 3 and, thus, reduce the analog signal in absolute value at the output of the receiving transducer 5. Consequently, as the plane of the additional emitter moves from the initial position, each subsequent digital value The code will be less than the previous one until the minimum of the signal at the receiving transducer 5 is reached by eliminating the influence of side lobes. Therefore, exceeding the value of the digital code recorded on the second channel over the previous one indicates the achievement of such a phase ratio of signals from the transducers. 3 and 23, when the influence of side lobes on the input signal of the receiving transducer will be minimal.

At the moment of exceeding, the code comparison circuit 17 generates a signal of a logical unit which, arriving at the counting input of control trigger 18, changes its state. At the inverse output of the control trigger 18, a signal of a logical unit appears, which, arriving at the second input of the logic element 7, opens it for passing the signal from the output of the phase detector 6 to the input of the analog-digital converter 8. Simultaneously, at the output of the trigger 18 logic zero, the clock pulse generator 19 is turned off and the logic element AND 13 is closed for passing the signal from the output of the receiving converter 5. In the absence of control pulses from the generator 19, the step control unit 20 The motor stops working, the shaft of the stepper motor 21 is fixed in a certain position, and with the help of the converter 22 the angle-movement fixes in space the position of the radiating surface of the additional radiating converter 23.

Further, the operation of the device continues in the second mode. The output signal of the master oscillator 1 through the line 2 delay enters the radiating converters

3 and 23. Reflected from the object under study

The 4 acoustic signal is converted into a receiving converter 5 into an electrical one and is fed to the first input of the phase detector 6, the second input of which receives the reference signal from the output of the delay line 2.

Through the open first element And 7 the amplitude-varying output signal of the phase detector 6 is fed simultaneously to the comparator 10 and to the analog-to-digital converter 8. Signals from the source 12 of the reference voltage of two levels corresponding to the lower and upper limits are also sent to the comparator noticeable effect of nonlinear distortion. As the output signal of the phase detector 6 increases by an amount corresponding to the displacement of the object under study 4 by the value d, where I is the ultrasound wavelength in the air, beyond which there are nonlinear distortions, the output signal of the phase detector 6 in the comparator 10 reaches one of the threshold levels. Then, a control signal appears at the output of the comparator 10, changing the delay time by a value corresponding to the phase change of the signal at the input of the phase detector 6 by 5f / 4. Thus, the operating point of the meter shifts to R / 8, which eliminates non-linear distortion. When the value of the input signal decreases and, consequently, the phase change decreases to 5 G / 4, the output value of the phase detector 6 decreases to one of the threshold voltages, which causes a negative pulse at the output of the comparator 10, which switches the switch 11 to the original condition. Line 2 delay changes phase to fi / 4, but in the opposite direction. Information about moving an object from phase detector 6 through analog 0

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the digital converter 8 is entered into the data processing unit 9.

The use of the proposed meter makes it possible to increase the accuracy of measurement of the parameters of unsteady vibroprocesses.

Claims (1)

The invention of the ultrasonic phase displacement meter, containing a series-connected master oscillator, a delay line with control inputs and a main radiating transducer, a series-connected receiving transducer, a phase detector, a first analog-to-digital converter and a unit 5 information processing, serially connected reference voltage source, comparator and the first switch, the outputs of which are connected to the control inputs of the delay line, the input of the first analog-digital converter is connected to the second input of the comparator, the output of which is connected to the second input of the information processing unit, different that, in order to improve the measurement accuracy, it is equipped with the first AND element included 5 between the phase detector and the first analog-to-digital converter, sequentially connected by the second element AND, the integrator, the second analog-digital converter, the second switch, the code comparison circuit, the control trigger, the clock generator, the stepper motor control unit, the step motor, the angle converter - linear displacement and an additional radiating transducer connected to the output of the delay line and made in the form of a ring, inside which it is centered with it The main radiating transducer is connected, the first input of the second element I is connected to the output of the receiving converter, and its second input is connected to the first output of the control trigger, the second output of which is connected to the second input of the first element I. five