SU817597A1 - Device for measuring gaps and vibrations - Google Patents

Description

one

The invention relates to electrical measuring technique and can be used to measure linear displacements and vibrations of electrically conducting objects without mechanical contact with them.

A device is known for measuring gaps between an intra-current transducer and an electrically conductive object. The measurement device includes a generator that contains a resonant circuit formed by a capacitor and an eddy current coil. To obtain a linear dependence of the output voltage on the measured gap, a linearizing circuit is used that is sensitive to changes in the amplitude of the generator voltage as the gap changes and is based on semiconductor diodes l.

A disadvantage of the known device is the low measurement accuracy due to the instability of the current-voltage xc1 characteristics of the semiconductor diodes of the linearizing circuit.

It is also known a device for measuring the distance between the sensor and the object being monitored. The device. Consists of a generator containing

a series of resonant circuits, a parametric eddy current transducer included in an oscillating circuit, and a differential voltage amplifier on two transistors with a current stabilizer. The eddy current transducer is turned on in such a way that the power losses in the resonant circuit are proportional to its effective series resistance. In this case, the amplitude of the current oscillations in the resonant circuit varies inversely with respect to the effective series resistance, thereby achieving the direct dependence of the output voltage of the device on the controlled gap 2.

0 The disadvantage of the device is the dependence of the parameters of the resonant circuits on changes in environmental parameters (mainly temperature), which reduces the accuracy

5 measurements.

The closest in technical essence to the present invention is a device comprising a generator of sinusoidal oscillations, a vortex-0 current transducer and an electronic circuit consisting of two channels for measuring vibration processes and an absolute gap channel.

The absolute gap channel includes an AC compensator amplifier, detector, lower filter. frequency and dial gauge. In order to obtain a linear dependence of the output voltage, a linearizing circuit also enters the channel of the absolute gap. Its effect is based on the nonlinearity of the initial part of the current-voltage characteristics of semiconductor diodes. The vibration measurement channel consists of ac compensators, a no-amp amplifier with adjustable gain, a detector, a low-pass filter and an oscilloscope. Moreover, in order to ensure the constant sensitivity of the device to vibrations when the absolute gap changes, the gain of the bandpass amplifier changes depending on the voltage change at the output of the channel of the absolute gap 3.

The drawback of the device is insufficient measurement accuracy, due to the use of semiconductor elements in the linearizing circuit.

The purpose of the invention is to improve the measurement accuracy, making it possible to present the measurement results in digital form.

This goal is achieved by the fact that a device for measuring gaps and vibrations, containing successively connected high-frequency generator, eddy-current transducer and detector, additionally introduced two diodes and two storage capacitors, a discharge resistor, two controlled keys, a logic cell, a driver rectangular pulses, a counter, a delayed pulse former, a comparator, the detector output being connected to the first storage capacitor via a diode, with another storage capacitor through the first controlled switch and the second diode connected in series, as well as with a logic cell, storage capacitors are connected to the comparator inputs, the discharge resistor is connected to the first storage capacitor using another controlled call, the input of the square I1 and 1 pulse generator is connected to the eddy current output the converter, and the output with the counter input of the counter, the control input of which is connected to the output of the logic cell, the output of the counter is connected to the control input of the first controlled to The switch is also connected to the delayed pulse shaper, the output of which is connected to the control input of another control key.

The drawing shows a structural diagram of the device.

In the device, the output of the high-frequency generator 1 is connected to an eddy-current transducer 2, the output of which is connected to the input of the detector 3, the output of the detector 3 is connected via a diode 9 to a storage capacitor 11, to the junction point of the diode; 9 and the storage capacitor 11 are connected to the discharge resistor 13 and one input of the comparator 4, the second output of the resistor 13 is connected to the switch 14, the output of the detector is also connected via the switch 15 and the diode 10. another storage capacitor 12 and the second input of the comparator 4. To the output of the detector 3 the input of the logic cell 5 is also connected, the output of which is connected to the control input of the counters, the counting input of the counter 6 is connected to the output of the former 7 rectangular pulses, the input of which is connected to the input of the detector 3, the output of the counter 6 is connected to the control go key 15 and to an input of the delayed pulse 8, the latter output is connected to the control input of switch 14.

The operation of the device is as follows.

From the high frequency generator 1, the voltage is applied to the eddy current transducer 2, whose parameters are functionally related to the gap between the eddy current transducer.

2 and the object of control. As a result of the vibration displacements of the test object, the high frequency voltage on the eddy current transducer turns out to be modulated. This modulated voltage is detected by detector 3 and through diode 9 is fed to a storage capacitor 11, which is charged to a voltage and U is the maximum value of the modulating voltage). In this case, a leading edge of the output pulse is formed at the output of the comparator. The envelope corresponding to the vibration displacements of the object under test from the detector output

3 also enters the input of the logic cell 5, where the selection of the minimum envelope value occurs. At the moment of time corresponding to the minimum envelope value, at the output of logic cell 5 a pulse appears that goes to the control input of counter b, to the counting input of which rectangular pulses from the output of the high-frequency voltage eddy current transducer 2. At the moment of the arrival on the control input of the counter 6 with them: pulse, a pulse appears from the logic cell 5 at its output, which

Claims (1)

SUMMARY OF THE INVENTION A device for measuring gaps and vibrations, comprising a high-frequency generator, an eddy current transducer and a detector connected in series, characterized in that, in order to improve the measurement accuracy, two diodes and two storage capacitors, a discharge resistor, two controlled keys, a logic cell are additionally introduced , a rectangular pulse shaper, a counter, a delayed pulse shaper, a comparator, the detector output being connected to the first storage capacitor through a diode e, with another storage capacitor through the first controlled key and the second diode connected in series, as well as with the logic cell, the storage capacitors are connected to the inputs of the comparator, the discharge resistor is connected to the first storage capacitor using another controlled key, the input of the square-wave driver is connected to the output eddy current transducer, and the output with the counter input of the counter, the control input of which is connected to the output of the logic cell, the output of the counter is connected to the control conductive input of the first controllable switch and a delayed pulse shaper, the output of which is connected to the control input of the other controllable switch.