SU1740995A1 - Device for non-contact measurement of vibration parameters - Google Patents

Abstract

The invention relates to a vibration technique and can be used to measure the vibration parameters of various microminiature electronic equipment with a non-contact radio wave method. The aim of the invention is to increase the measurement accuracy at distances exceeding the focal length of the viewfinder, as well as to extend the functionality by measuring the LU-ULJl u distance from the source of mechanical vibrations. The viewfinder 5 is mounted on the antenna 4 on a rotating base with a scale 6 of the reference of the angular displacement of the optical axis. The device contains a phase shifter 3 connected to the second output of the directional coupler 2, and output to the antenna input 4, the next filter 8 connected to the output of the amplitude detector 7 by the first input, the second input to the second output oscillator 10, the first output of which is connected to a second input of the phase-to-distance unit 13; successively connected power amplifier 11 and a vibrator 12, the first input of the recorder 9 is connected to the output of the tracking filter 8 of the conversion unit 13 and the first input of the phase-distance Whose output is connected to a second input registrar 9, connecting the output to the input of oscillator 10, the oscillator output 1 is connected to the input of the directional coupler 2. 2-yl. L A (L 2 O Yu SQ ate

Description

The invention relates to a vibration technique and can be used to measure the vibration parameters of various products, in particular microminiature electronic equipment, by a non-contact radio wave method.

It is known that with a change in the distance between the contactless measuring device and the product under investigation, the threshold of sensitivity and, consequently, the range of measured vibration levels may change.

In the known device, an increase in the accuracy and expansion of the level range is achieved by introducing the reference values of the vibrating displacement signals into the memory unit and their subsequent comparison with the signals at intermediate distances.

However, ensuring a constant measurement accuracy is limited to the class of measured vibration processes with constant excitation frequencies, the contribution of changes in the levels of which to the amplitude of the reference signals at corresponding distances exceeds the contribution due to the change in distance, or with the linear nature of such dependencies.

The closest in technical essence to the present invention is a device for contactless measurement of vibration parameters, comprising a series-connected auto generator, a directional coupler and an amplitude detector, as well as a recorder, a vibrator, an antenna and an optical viewfinder whose optical axis intersects with the antenna horn radiator of the antenna.

The known technical solution allows the measurement of vibration parameters in the far-field radiation zone of the antenna.

constructively complex objects at the frequencies of forced and resonant oscillations in a wide range of changes in their levels. Expansion of the range and increase in local accuracy of measurements is achieved by expanding the sensitivity threshold both by using the effect of dynamically tightening the frequency of the oscillator and by spatially adjusting the device. The alignment is carried out by combining the geometric axis of the horn emitter with the optical axis of the optical viewfinder mounted on the horn emitter, the focal distance of which is chosen equal to the distance to the element under study, at the location of the investigated element.

If this distance is smaller than the focal length, the image of the surface of the element under study is blurred. On the contrary, such an image is sharp if the distance is equal to or greater than the focal length. Visually observable and quantitatively recorded oscillations in amplitude and frequency are related to those elements of the surface of the element under investigation, at which the center of the optical viewfinder is directed at the time of measurement.

However, achieving the minimum total measurement error by measuring at distances corresponding to the focal length of the alignment system leads to a number of limitations that prevent the wide use of the known device. Restrictions may arise, for example, when conducting rapid analysis in the process of non-destructive testing of the dynamic characteristics of structurally complex electronic products over measurement distances other than the focal ones. Measurements at distances exceeding the constructively permissible focal length make it necessary to measure the relative values of the vibration displacement levels at the reference distances and the subsequent recalculation for these distances at the same excitation frequencies of the calibrated vibration displacements, which correspond to the focal length. The complexity of taking into account the nonlinear nature of such dependencies leads to the fact that the total measurement error increases.

The purpose of the invention is to increase the accuracy of changes over distances exceeding the focal length of the viewfinder, as well as to expand the functionality by measuring the distance from the source of mechanical vibrations.

The goal is achieved in that the device containing a series-connected oscillator, a directional coupler and an amplitude detector, as well as a recorder, a vibrator, an antenna and an optical viewfinder, whose optical axis intersects with the electric axis of the antenna horn emitter, is fitted with a phase shifter connected in series with a following filter and a conversion unit connected in series by a master oscillator and a power amplifier, the first input of the following filter is connected to the output amp itudnogo detector, the second input - to the second output of the master oscillator, and an output - to a first input of recorder, with the second input of which is connected to the output conversion unit, recorder output is connected to the input of the master oscillator, a first output connected to the second input

the conversion unit, the output of the power amplifier is connected to the input of the vibrator, the input of the phase shifter is connected to the output of the directional coupler, and the output to the input of the antenna, the viewfinder is mounted on the antenna on a rotating base with the reading scale of the angular displacement of the optical axis.

FIG. 1 shows a functional diagram of the measurement device; in fig. 2

- use of the device for measuring vibration parameters and distance from the product.

In FIG. 2, the following notation is adopted: IF is the distance between the products and the antenna, corresponding to the focal length of the viewfinder; x is the distance between the product and the antenna when the viewfinder focal length is exceeded; OF and Ox are, respectively, the point of intersection of the optical axis of the viewfinder with the geometric axis of the antenna at a distance from the product equal to or greater than the focal distance of the viewfinder; AP and A. Y. - angular displacement of the optical axis of the viewfinder.

The device (Fig. 1) includes an auto-oscillator 1, a directional coupler 2, a phase shifter 3, an antenna 4, a viewfinder 5, a scale 6 for reading out the angular displacement of the viewfinder, an amplitude detector, a tracking filter 8, a recorder 9, a master oscillator 10, a power amplifier 11 , vibrator 12, conversion unit 13, rectifier 14, comparator 15, AND 16 gate, driver 17, phase period counter 18, frequency converter 19

-purpose.

The device works as follows.

The voltage of the microwave signal emitted by the oscillator 1, through the directional coupler 2 and the phase shifter 3 is fed to the input of the receiving-emitting antenna 4, the geometric axis of the radiation pattern of which is oriented to the element being investigated 20. When the input of the autogenerator 1 is applied, it is reflected directly from the product 20 signals appear disturbances in the conductivity of the autodyne system - load. These disturbances are accompanied by static (and with mechanical vibration excitations — dynamic) by the frequency of the radiation signal. As a result, amplitude-frequency modulation of the voltage of the autodyne radiation signal occurs. The low-frequency envelope of this signal is extracted at the output of the amplitude detector 7 and, in order to provide greater selectivity and noise immunity, is fed to the input of the following filter 8. From the output of the following filter 8, the voltage of the signal carrying the information on the change in distance and parameters

vibrations of the product, are fed to the first inputs of the conversion unit 13 and the recorder 9. To isolate information on the change in distance, the difference in voltage of the output signals is compared to the rectifier 14

and the first output of the driver 17 with the voltage threshold of the comparator 15 and generate signals of high and low logic levels. In case of occurrence on the first and second inputs of the circuit

the logic element AND 16 simultaneously signals high levels, respectively, from the output of the comparator 15 and from the second output of the imaging device 17, the voltage of the triggering impulse occurs at the input of the counter 18 phase periods. When the distance from IF to Ix is changed, the number of trigger pulses is determined by the number of periods of the phase of the carrier signal. Synchronization start counter 18 with moments

passing the phase angles corresponding to the maximum values of the voltage signal of the detector 7 is carried out by the output signals of the former 17. For this, in block 17 short output pulses are formed with a shift between the channels by the delay time of the operation of the signal of the master oscillator 10. From counter 18 output through converter

19, the frequency - voltage of the measured signal is fed to the input of the recorder 9. The excitation of mechanical oscillations of the product 20 is performed by the master oscillator 10 through the power amplifier 11 to the input of the vibrator 12. The voltage of the signals from the second output of the master oscillator 10 is used to synchronize the tuning with a change in the excitation frequency frequency tracking filter 8. Change control

excitation frequency voltage of the output signal of the recorder 9, which is fed to the input of the master oscillator 10. At the first input of the recorder 9 instantaneous values of the voltage of the measured vibration signals can be represented as:

55

Ui (t) A-x (0) Sirb "x 0) -UЈ

H)

: „2

And a L- P-Sin p0 J

where x (o) is the vibration displacement;

I am the circular frequency of the vibration;

A (p0 r, ftte Po, D, F2, So, L) is the conversion coefficient based on the vibration displacement; p0 is the phase shift of the signal of the carrier frequency MO in the static tightening mode;

r, Ro, P are, respectively, the reflection coefficient and power values of the signals at the output of the autodyne and reflected from the product;

D and F2 are the antenna ratio and radiation pattern, respectively;

So is the effective reflecting surface of the element under study; and - instrumental coefficient.

Taking into account that in the process of measuring the parameters D, F, g P0,, So Const, from relations (1) we have:

a L P with ro-that-L;

BUT

I

about

when p0 - k L f

where, 1,2, ...

The maximum levels of the signals U i (t) can be achieved at the measurement distances between the autodyne and the product, equal to:

, 1 ... Cr, KF

2f0 (lF) -JT

2

) (3)

where L co and Isle (o) are respectively the ranges of static and dynamic radiation frequency tightening (V0;

ro OF) is the value of the phase angle p0 at the distance.

For distances exceeding the focal length of the optical viewfinder lx IF within the device sensitivity threshold, we have:

L lF + lxtx (0);

 l C g (2Kx + 1), Dy + (o) .- 1 + ig; ) P

Тъ1 +

 7G

Kh

(1x) -7G

(four)

2

0

where p0 (1x) is the value of the phase angle p0 (IF) at 1X IF.

Calibration and measurement of the vibration parameters x (0) and T of the relation (1) are carried out, providing in accordance with the relations (3) and (4) of measurement and control of the distance L by the magnitude of the voltage of the signal measured at the second input of the recorder 9 :

U2Oo) mL

(five)

15

20

25

thirty

(o) 35

40

where hn is a constant value corresponding to a distance conversion factor.

The control of the distance Ix is implemented by the conversion unit 13 (counting roughly), which is refined by the phase shifter 3 (counting accurately), providing the magnitude of the signal Ui (t) (t) max. Placing the device at a distance from the product and orienting about; The tactile axis of the alignment system and the antenna pattern on the element under study (OF point in Fig. 2), using a phase shifter 3 at specified levels and excitation frequencies, tune the measuring path to the voltage of the signals at the recorder inputs 9 corresponding to the values:

Ui (t) 4Jlmax (t) and U2 (pb) U2 po (Ix)

and determine the calibrated values of Xk (0, IF) and AI (| F) at # $ k. Under the same excitation conditions, remove the device from the product at a distance of lx IF and provide a voltage signal Lh (t) at maximum levels x, establish the correspondence of the measured values with the calibrated ones:

X (0.1X) P -Xk (O.lx)}

45

Where

Ul (OJx) A (lF)

W SCHF (T7)

According to the magnitude of the voltage of the signals U2 (the distances x are determined in relative values of the distance IF, calibrated in whole wavelengths, the frequency of the signal w 0

lx Ј IF

Where

CE || PTA 1

The assumption that x (0), „, is appropriate (Oo

In FIG. 2 we have;

L lx + f sinap

"X arctg (1 + g

Ix

;)

(()

PCOS CCFJ

From relations (6), based on the measured values of Ix and the known parameters F and a p of the adjustment system, determine the angular displacement of the optical axis a, which is set on a scale of 6. The element of the product to which the center of the crosshair of the optical viewfinder 5 ( point Ox in Fig. 2), corresponds to the test. As a result of continuous monitoring of the distance and high level of the sensitivity threshold, the proposed device, compared with the known, allows calibration and measurement of vibration parameters with high local accuracy and sensitivity at distances exceeding the focal distance of the alignment system viewfinder; simultaneously with the measurement of vibration parameters, measure and control the distance between the autodyne and the product; to carry out high-quality express analysis with non-destructive testing of the vibration parameters of various structurally complex electronic products.

When testing products with resonant frequencies in the range of vibration frequencies of 10-3000 Hz and using the GMTD as the autogenerator of the millimeter wavelength range, the measurement errors of vibration are not worse than ± 1% in the range

Y-W

levels of 20–10 mm, distance to microns within 110–750 mm.

Claims (1)

Invention Formula ten 15 20 25 thirty 35 40 A device for contactless measurement of vibration parameters, comprising a series-connected oscillator, a directional coupler and an amplitude detector, a recorder, a vibrator, an antenna with a horn transmitter, and an optical viewfinder whose optical axis intersects the antenna horn radiator of the antenna, characterized in that, in order to increase accuracy measurements at distances exceeding the focal distance of the viewfinder, as well as extending the functionality by measuring the from the source of mechanical oscillations, it is equipped with a phase shifter, serially connected by a tracking filter and a conversion unit, connected in series by a master oscillator, a power amplifier, the first input of a servo filter is connected to the output of the amplitude detector, the second input - to the second output of the master oscillator, and the output the recorder input, with the second output of which the output of the conversion unit is connected, the output of the recorder is connected to the input of the master oscillator, the first input of which is connected to the second converting an input unit, an output power amplifier connected to the input of the vibrator, the phase shifter input coupled to an output directional coupler, and The output from the antenna input viewfinder is mounted on the rotating antenna based on a scale of reference angular displacement of the optical axis. 777ТГПТ77Т # teЈ AND X 20