RU185575U1 - Device for dismantling the operability of a vibrometer with a piezoelectric vibration transducer - Google Patents

Abstract

The utility model relates to measuring technique and can be used for complex dismantling testing of a vibrometer with its piezoelectric vibration transducer. The device for checking the operability of the vibrometer contains a piezoelectric vibration transducer 1 installed at the object 2, connected via a connecting cable 3 to the measuring circuit 4. The measuring circuit 4 of the vibrometer contains a two-channel three-position switch 6 with changeover contacts, a test signal source 7, a reference voltage source 8, a matching amplifier 9 with two input resistors 10 and 11 and a capacitor 12 connected to a matching amplifier, a DC voltage source 13, measure The main unit is 14, the storage unit is 15, the comparison unit is 16, and the fault indicator is 17. A two-channel three-position switch, when switching the connections of the blocks of the measuring circuit, implements three modes of operation of the device. When the switch is moved to the first position of its changeover contacts of both channels, the device is ready to work in the measurement mode of the current value of the object acceleration. When the switch is switched to the second position of its changeover contacts of both channels, the device is ready for operation in the mode of dismounting the operability of the vibrometer — its piezoelectric vibration transducer together with the measuring circuit. When the switch is moved to the third position of its changeover contacts of both channels, the device is ready for operation in the mode of checking the operability of the measuring circuit of the vibrometer. The technical result is the use of a harmonic electric signal at a base frequency, for example, 160 Hz, to determine the cause of a malfunction of the vibrometer: vibration transducer or its measuring circuit. 1 ill.

Description

The utility model relates to measuring technique and can be used to comprehensively check the operability of a vibrometer with its piezoelectric vibration transducer with a connecting cable and a measuring circuit without removing the vibration transducer from the object for measuring vibration parameters.

Vibrometers with piezoelectric transducers are widely used to measure vibration parameters of objects designed to operate for long periods of time with minimal maintenance in harsh operating conditions (elevated temperature, humidity, presence of aggressive environment, etc.). For this reason, it may cause malfunctions or deviations from the characteristics specified in regulatory documents of both piezoelectric vibration transducers and the measuring circuit of vibrometers. In these cases, the measurement of vibration parameters will be carried out with significant errors (exceeding the permissible limits) or information about them will be completely absent, as a result, failure of the entire unit is possible, the vibration parameters of which should be measured by the vibrometer. Replacing a failed vibration transducer is often an expensive operation (and sometimes it is simply not possible without lengthy and costly work), so periodic monitoring of the vibrometer’s performance without dismantling the vibration transducer installed in the place of operation and its measuring circuit is an urgent task.

A device is known that implements a known method of dismounting the operability of a piezoelectric vibration transducer (“Method for verifying a piezoelectric vibration transducer without dismantling from a test object”, (RU 2358244, G01H 11/08, 06/10/2009).

The device contains a piezoelectric vibration transducer, matching device, generator, voltmeter and resistors.

When the piezoelectric vibration transducer is periodically calibrated without disassembling it from the installation object, from a sinusoidal signal generator, the calibrated vibration transducer is sequentially provided with the frequencies of its operating range at the frequencies being verified, the normalized electrical signal of the voltage of the mechanical excitation of the vibration transducer is fed and the current voltage value is recorded on the resistor included in the signal circuit break vibration transducer. Compared to the current value obtained with the value obtained when the calibrated vibration transducer was excited by vibration acceleration at a given frequency during the initial calibration, the state of operability of the calibrated vibration transducer is judged.

The reasons that impede the achievement of the technical result indicated below when using the known device include the inability to verify the operability of measuring circuits and piezoelectric vibration transducers with an electrode not insulated from the housing (both electrodes of the piezoelectric vibration transducer must be isolated from the housing to replace the mechanical excitation of the vibration transducer by supplying a normalized electrical signal) .

A device for dismounting the health of a piezoelectric vibration transducer ("Piezoelectric sensors monitoring system", RU 128321 U1, G01H 17/00, 05/20/2013), which, by the combination of essential features, is the closest analogue of the claimed device.

The known device comprises a sensor (a piezoelectric vibration transducer with piezoelectric electrodes isolated from its body) and a measuring circuit connected to it via a three-wire communication line, containing a two-position switch with two groups of changeover contacts connected to a measurement and control unit, a test voltage source, voltage divider, an element comparison, the source of the reference signal, the indicator of the malfunction of the sensor, the second source of the reference signal and the second element sake of compari- son.

The known device alternately (periodically) performs work in two modes - working and control, checking the health of the piezoelectric sensors installed on the object, and an additional assessment of the health of the measurement and control unit.

In the operating mode of measuring the current values of the object’s vibration parameters, the device’s piezoelectric vibration transducer is connected via a switch to the input of the measurement and control unit, with which the vibration parameters generated by the object on which the piezoelectric vibration transducer is mounted are determined.

In the control mode, the switch connects the test signal generator with the piezoelectric electrodes of the piezoelectric transducer, in which the mechanical vibrations of the piezoelectric element excited by the signals of the test voltage source arise, causing the appearance of an electric signal due to the direct piezoelectric effect, which is compared in the first comparison element with the reference signal of the first reference signal source. Since the piezoelectric transducer is first checked together with the measurement and control unit, if there is a deviation from the reference signal, it is concluded that the measurement and control unit is not working properly, which is indicated by a malfunction indicator. Check the operation of the measurement and control unit. With a working unit of measurement and control, the correct operation of the piezoelectric vibration transducer is checked. To do this, the test signal is disconnected from the piezoelectric transducer, after which damped mechanical vibrations occur at the frequency close to the resonant frequency. These oscillations due to the direct piezoelectric effect cause the appearance of an electrical signal on the plates of the piezoelectric element. This signal is compared in the second comparison element with a predetermined exemplary signal from a second source of exemplary signals. In case of mismatch of the electric signal on the piezoelectric element plates to the exemplary signal of the second source of exemplary signals, the second comparison element fixes the malfunction of the piezoelectric transducer, which is indicated by the malfunction indicator. In the absence of deviations of the damped oscillations compared with the reference signal, a conclusion is drawn about the correct operation of the piezoelectric transducer.

The reasons that impede the achievement of the technical result indicated below when using the known device include its complexity and the ability to verify the performance of vibrometers with piezoelectric vibration transducers only with electrodes isolated from the housing.

The task to which the claimed utility model is directed is to simplify the design and expand the range of types of piezoelectric vibration transducers in vibrometers during their comprehensive verification without dismantling the piezoelectric vibration transducer from the installation site.

The technical result obtained by the implementation of the utility model consists in providing the possibility of a comprehensive check of the operability of vibrometers using a harmonic electrical signal (for example, at a base frequency of 160 Hz), followed by determining the cause of the failure of the vibrometer: a piezoelectric vibration transducer or measuring circuit.

The specified technical result in the implementation of the utility model is achieved by the fact that in the inventive device for dismounting the operability of a vibrometer with a piezoelectric vibration transducer, comprising a measuring circuit connected to the vibration transducer via a connecting cable, including a two-channel switch with changeover contacts, a measuring unit, a test signal source, a comparison unit and fault indication unit, unlike the known device, a two-channel switch performed by three-position, and the measuring circuit is equipped with a storage unit, a DC voltage source, a reference voltage source and a matching amplifier with input - two resistors and a capacitor, the first inputs are non-inverting and the second is inverting, the third input connected to the DC voltage source and output at the same time, to the change-over contacts, the first and second positions of the first channel of the switch, the first signal signal of the piezo electrode is connected via a signal cable with a screen lementa vibrator mounted on the vibration object of measurement, connected to the common bus, together with the signal cable shield and the second contact may insulated from the body electrode of the vibrator; the contact of the first position of the second channel of the switch is connected to the common bus, and the contacts of the second and third positions of the second channel of the switch are connected to the output of the test signal source, also connected to the common bus; the movable contact of the first channel of the switch through the input resistor is connected to the inverting input of the matching amplifier connected to a common bus; the movable contact of the second channel of the switch through the input capacitor is connected to the non-inverting input of the matching amplifier, the output of the reference voltage source, also connected to the common bus, is connected to the same input of the matching amplifier through the input resistor; a measuring unit is connected to the output of the matching amplifier, to the first output of which a storage unit, a comparison unit and a fault indicator are connected in series, the second output of the measuring unit being connected to the second input of the comparison unit.

In FIG. a schematic diagram of a device for checking the operability of a vibrometer with a piezoelectric vibration transducer is shown.

A device for checking the operability of the vibrometer (Fig.) Contains a piezoelectric vibration transducer 1 with a piezoelectric element 1 ₁ , with its first signal electrode with a contact 1 ₂ and a second electrode possibly isolated from the body of the vibration transducer 1 with a contact 1 ₃ . The vibration transducer 1 is installed on the object 2, the vibration acceleration of which affects the piezoelectric element 1 _{1 of the} vibration transducer 1. The signal contact 1 _{2 of the} piezoelectric element 1 ₁ through the wire 3 _{1 of the} connecting cable with the screen 3 _{2 is} connected to the measuring circuit 4, while the screen 3 _{2 of the} connecting cable together with the contact 1 _{3 of the} second electrode of the piezoelectric element 1 ₁ and the object 2 are connected to a common bus 5 of the measuring circuit 4.

The measuring circuit 4 of the vibrometer contains a three-position two-channel switch 6 with changeover contacts 6 _{1- (1, 2, 3)} and 6 _{2- (1, 2 3)} , a source of test signal 7, a reference voltage source 8, matching amplifier 9 with input two resistors 10 and 11 and a capacitor 12 connected to a matching amplifier 9 of a DC voltage source 13, a measuring unit 14, a storage unit 15, a comparison unit 16 and a fault indicator 17.

The source of the test signal 7, the reference voltage source 8 and the matching amplifier 9 are connected to a common bus 5.

Contact 6 _{2-1 of the} first position of the second channel 6 _{2 of the} switch 6, the source of the test signal 7, the reference voltage source 8 and the matching amplifier 9 are connected to a common bus 5. To the contacts of the second 6 _2-2 and third 6 _2-3 positions of the second channel 6 ₂ switches 6 connected to the output of the test signal source 7.

The movable contact of the first channel 6 _{1 of the} switch 6 through the input resistor 10 is connected to the inverting input 9 _{2 of the} matching amplifier 9, and the movable contact of the second channel 6 _{2 of the} switch 6 through the input capacitor 12 is connected to the non-inverting input 9 _{1 of the} matching amplifier 9, to the same input 9 ₁ matching amplifier 9 through the input resistor 11 is connected to the output of the reference voltage source 8.

The DC voltage source 13 is connected to the input 9 _{3 of the} matching amplifier 9, to the output 9 _{4 of} which are connected in series, the measuring unit 14, the storage unit 15, the comparison unit 16 and the fault indicator 17. The second output 14 _{2 of the} measuring unit 14 is additionally connected to the second input 16 ₂ comparison blocks 16.

During the initial calibration, which is carried out in accordance with GOST R 8.669-2009 when the piezoelectric vibration transducer 1 of the vibrometer is put out of production, the required parameters are determined, including its capacity and the actual value of the conversion coefficient (pCl / ms ^{-2) of the} vibration transducer at the base frequency (for example , 160 Hz). When determining the actual value of the conversion coefficient, switch 6 is set to 6 _1-1 - 6 _2-1 .

соответствующее действующему на вибропреобразователь виброускорению (например,

=10 м/с²), и действительное значение коэффициента преобразования

сохраняют в запоминающем блоке 15.The output voltage of the matching amplifier 9

corresponding to vibration acceleration acting on the vibration transducer (e.g.

= 10 m / s ² ), and the actual value of the conversion coefficient

stored in the storage unit 15.

. Значение суммарной емкости

сохраняют в запоминающем блоке 15.After installation at the place of operation of the piezoelectric vibration transducer 1 with a standard connecting cable 3 determine their total capacity

. Value of total capacity

stored in the storage unit 15.

подбирают таким, чтобы значение амплитуды (с.к.з.) напряжения на выходе 9₄ согласующего усилителя 9 было быIn the measuring circuit 4 (FIG.), The three-position switch 6 is moved to the second position of the contacts 61.2 - 62-2 and a harmonic signal is fed to the non-inverting input 9 from the output of the test signal source 7 through the input capacitor 12_one matching amplifier 9. The amplitude or mean square value (rms) of an alternating signal at a non-inverting input 9_onematching amplifier 9

selected so that the value of the amplitude (scc) voltage at the output 9_four matching amplifier 9 would be

должно быть равно напряжению, соответствующему виброускорению, действующему на пьезоэлектрический вибропреобразователь при первичной поверке (например,

=10 м/с²). Значение напряжения

сохраняют в запоминающем блоке 15.those.

should be equal to the voltage corresponding to the vibration acceleration acting on the piezoelectric vibration transducer during initial calibration (for example,

= 10 m / s ² ). Voltage value

stored in the storage unit 15.

(например, на базовой частоте 160 Гц). Спомощью измерительного блока 14 измеряют напряжение на выходе 9₄ согласующего усилителя 9. Амплитуду (с.к.з.) напряжения на выходе источника тестового сигнала 7

подбирают такой, чтобы значение амплитуды (с.к.з.) напряжения на выходе 9₄ согласующего усилителя 9

было равно

, т.е. напряжению, соответствующему виброускорению, действующему на пьезоэлектрический вибропреобразователь при первичной поверке (например,

=10 м/с²). Значения напряжений

и

также сохраняют в запоминающем блоке 15.The three-position switch 6 is moved to the third position of the contacts 6 _1-3 - 6 _2-3 (in this switch position, the contact of the signal electrode 1 _{2 of the} piezoelectric element 1 _{1 of the} piezoelectric vibration transducer 1 is disconnected from the matching amplifier 9), it is fed from the output of the test signal source 7 to a non-inverting input 9 ₁ matching amplifier 9 electrical signal

(e.g. at a base frequency of 160 Hz). Using the measuring unit 14, the voltage at the output 9 _{4 of the} matching amplifier 9 is measured. The amplitude (rms) of the voltage at the output of the test signal source 7

choose such that the value of the amplitude (RMS) of the voltage at the output 9 ₄ matching amplifier 9

was equal

, i.e. voltage corresponding to vibration acceleration acting on the piezoelectric vibration transducer during initial calibration (for example,

= 10 m / s ² ). Voltage values

and

also stored in the storage unit 15.

The three-position switch 6 is transferred to the first position of the contacts 6 _1-1 - 6 _2-1 , after which the device is ready for operation in the vibration acceleration measurement mode.

A device for dismounting the operability of a vibrometer with a piezoelectric vibration transducer operates in three modes:

- Measurement of the current value of the vibration parameters of the object.

- Dismantle-free operation test of the vibrometer (measuring circuit in conjunction with a piezoelectric vibration transducer).

- Checking the operability of the measuring circuit of the vibrometer (without a piezoelectric vibration transducer).

Measurement of the current value of the vibration parameters of the object.

The three-position switch 6 is transferred to the first position of the contacts 6 _1-1 - 6 _2-1 (Fig.), After which the device is ready for operation in the vibration acceleration measurement mode. Information about the vibration acceleration acting on the piezoelectric vibration transducer 1 from the side of the object 2 is obtained from the measuring unit 14.

(например, на базовой частоте 160 Гц). С помощью измерительного блока 14 измеряют напряжение

на выходе 9₄ а согласующего усилителя 9 и сравнивают его значение с начальным значением напряжения

сохраненным в запоминающием блоке 15. Если амплитуда напряжения на выходе 94 согласующего усилителя 9Dismantle-free operation test of the vibrometer (measuring circuit in conjunction with a piezoelectric vibration transducer). After a time interval, regulated in the technical conditions for the device, they check the operability of the vibrometer with a piezoelectric vibration transducer. To do this, transfer the three-position switch 6 to the second position of its contacts 6_1-2 - 6_2-2 (Fig.). From the output of the test signal source 7 to non-inverting input 9_one matching amplifier 9 provides an electrical signal

(e.g. at a base frequency of 160 Hz). Using the measuring unit 14 measure the voltage

 at the exit 9_four and matching amplifier 9 and compare its value with the initial voltage value

 stored in the storage unit 15. If the voltage amplitude at the output 94 of the matching amplifier 9

(the deviation should not exceed the value regulated, for example, by 5% for the device), then they decide on the working condition of the piezoelectric vibration transducer 1, connecting cable 3, matching amplifier 9 and other units included in the device (measuring circuit of the vibrometer).

отклонение превышает значение, регламентированное в технических условиях на устройство, то вначале проводят измерение емкости соединительного кабеля 3 вместе с емкостью пьезоэлектрического вибропреобразователя 1. При текущем значении суммарной емкости

принимается решение об исправности соединительного кабеля 3 и подключенного к нему пьезоэлектрического вибропреобразователя 1.If

the deviation exceeds the value regulated in the technical specifications for the device, then first measure the capacitance of the connecting cable 3 together with the capacitance of the piezoelectric vibration transducer 1. At the current value of the total capacity

a decision is made on the serviceability of the connecting cable 3 and the piezoelectric vibration transducer 1 connected to it.

Checking the operability of the measuring circuit of the vibrometer (without a piezoelectric vibration transducer)

(например, на базовой частоте 160 Гц). С помощью измерительного блока 14 измеряют напряжение

на выходе согласующего усилителя 9 и сравнивают значение измеренного напряжения с сохраненным в запоминающем блоке 15 начальным значением напряжения

. Если амплитуда (с.к.з.) напряжения выходе согласующего усилителя 9The three-position switch 6 is moved to the third position of the contacts 6 _1-3 - 6 _2-3 (Fig.) (Thus, the piezoelectric vibration transducer is disconnected from the matching amplifier), an electrical signal is supplied from the output of the test signal 7 to the non-inverting input 9 _{1 of the} matching amplifier 9

(e.g. at a base frequency of 160 Hz). Using the measuring unit 14 measure the voltage

the output of the matching amplifier 9 and compare the value of the measured voltage with the initial voltage value stored in the storage unit 15

. If the amplitude (RMS) of the voltage output of the matching amplifier 9

,

,

^в запоминающем блоке 15).and the deviation exceeds the value regulated in the technical specifications for the device, then they conclude that the matching amplifier is malfunctioning or there is a malfunction in the remaining units included in the device (for example, unauthorized change of values

^{in the} storage unit 15).

The blocks of the claimed device 7, 8, 9, 13-17 can be implemented in digital form using the DAC-ADC board.

Thus, it is seen that the above information confirms the possibility of implementing a device for dismantling a comprehensive health check of a vibrometer with a piezoelectric vibration transducer, to achieve the specified technical result and solve the problem.

Claims (1)

A device for dismantling the operability of a vibrometer with a piezoelectric vibration transducer, comprising a measuring circuit connected to the vibration transducer via a connecting cable, including a two-channel switch with changeover contacts, a measuring unit, a test signal source, a comparison unit and a fault indication unit, characterized in that the two-channel switch is made of three-position, and the measuring circuit is equipped with a storage unit, a constant voltage source then ka, a reference voltage source and a matching amplifier with input - two resistors and a capacitor, the first inputs are non-inverting and the second is inverting, the third input is connected to a DC voltage source, and the output; at the same time, to the change-over contacts of the first and second positions of the first channel of the switch, the first one is connected to the signal cable of the piezoelectric element of the vibration transducer installed on the object of vibration measurement connected to the common bus together with the screen of the signal cable and the contact of the second, possibly isolated from the housing vibration transducer electrode; the contact of the first position of the second channel of the switch is connected to a common bus, and the output of the test signal source connected to the common bus is connected to the contacts of the second and third positions of the second channel of the switch; the movable contact of the first channel of the switch through the input resistor is connected to the inverting input of the matching amplifier connected to a common bus; the movable contact of the second channel of the switch through the input capacitor is connected to a non-inverting input of the matching amplifier, to the same input of the matching amplifier through the input resistor is connected the output of the reference voltage source, also connected to the common bus; a measuring unit is connected to the output of the matching amplifier, to the first output of which a storage unit, a comparison unit and a fault indicator are connected in series, the second output of the measuring unit being connected to the second input of the comparison unit.

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