RU2654996C1 - Device for equipment diagnostics (measuring channel) - Google Patents

Abstract

FIELD: metrology.

SUBSTANCE: invention relates to vibrational metrology. Device for diagnosing equipment consists of a primary and a secondary converter. Primary converter contains a temperature sensor, a low-pass filter, a charge amplifier, a normalizing amplifier, an output stage, a vibration sensor, and an alternating voltage to current converter. Secondary converter contains a spark protection barrier, a buffer stage, a direct voltage to current converter, a proportional filter, a second buffer stage, a high pass filter, a bandpass filter, a peak detector, a second direct voltage to current converter, an integrator, a root mean square detector, a third direct voltage to current converter, a narrowband filter, second peak detector, average detector, logarithm, first and second buffer averaging stages, second logarithm. Vibration sensor consists of a piezo-bimorph, a bolt made of non-magnetic steel, precision washers. Case of the primary converter contains a threaded pin and a four-prong connector. Primary and secondary converters are connected by a communication line with a common shield. Temperature sensor is glued in a cylindrical recess in the inner part of the housing.

EFFECT: providing the possibility of a one-time measurement of the levels of low-frequency and high-frequency vibrations, as well as temperature.

8 cl, 3 dwg

Description

The invention relates to measuring equipment and can be used to monitor, protect and diagnose industrial equipment that performs rotational and reciprocating movements during its operation in the energy sector, mechanical engineering and other industries and science.

The invention can be used both independently and as part of automated control systems, protection and diagnostics of industrial equipment, for measuring shock pulses by the resonance method (rolling bearings, cavitation of the pumped medium), as well as for measuring absolute vibration (vibration acceleration, vibration velocity, vibration displacement) and temperature diagnostic objects.

A known diagnostic system of rolling bearings according to the patent for utility model RU 100252, which is a table with a plate on which an induction motor is located, connected through a vibration-isolating coupling with a high-frequency spindle to install the mandrel with a bearing, a complex measuring device containing a piezoelectric holder is connected to the outer ring of the bearing a transducer with a force sensor that does not have a metal connection with the drive parts.

A known device for measuring vibration (options) according to the patent for invention RU 2382368, containing a piezoelectric transducer, instrumental amplifier and operational amplifier, the output of which is the output of the device. The outputs of the piezoelectric transducer are connected to direct and inverse inputs of the instrument amplifier, the first input of the gain setting of which is connected to the first output of the first resistor. The output of the operational amplifier is connected to its inverse input through a capacitor. The inverse input of the operational amplifier is connected through a second resistor to the output of the instrumental amplifier. The direct input of the operational amplifier is connected to a common bus. An inductance is introduced into the device, which is connected between the second output of the first resistor and the second input of the gain setting of the instrumental amplifier, and a third resistor is connected in parallel with the capacitor. Inductance is made in the form of an inertial mass mounted on a piezoelectric transducer.

A known vibrometer according to the invention patent RU 2046301, comprising a piezoelectric vibration transducer, a low-pass filter, a high-pass filter, first and second integrators, first and second amplifiers, a rms detector and an indication unit equipped with first and second switches, a measuring range switch, and a third amplifier , an analog-to-digital converter, connected in series by the unit for setting operating modes and the control unit. The vibrometer is the closest to the proposed device for diagnosing equipment according to the technical nature and the achieved result and is taken as a prototype.

Defects of rolling bearings are most often manifested in violation of the smoothness of surfaces or rolling bodies. When rolling, the balls of the bearing, rolling through such irregularities, experience collisions, which manifest themselves in the form of peaks of vibrational acceleration - shock pulses. Measurement of the amplitude of the shock pulses allows you to evaluate the condition of the bearing. Measurement of the pulse amplitude is possible both with a broadband system and with the help of a resonant circuit, which allows to increase the signal-to-noise ratio during measurements and thereby provides a more reliable determination of the state of the bearing, especially for small defects. The shock impulses of the bearing excite the resonant system the stronger, the more developed the defect of the bearing. From the measured value of the amplitude of the pulses at the output of the resonant system, the development of the bearing defect is estimated. To implement such a measurement, a stable resonance normalized in frequency and amplitude is required, which in known systems is implemented by specialized resonant sensors. However, such sensors cannot simultaneously measure vibration. Such devices operate exclusively at the resonance frequency, which significantly increases the cost of the system, since vibration measurement requires additional vibration measurement sensors, which in turn do not have resonance characteristics suitable for measuring shock pulses. Thus, the known devices allow you to measure and control only selective diagnostic parameters, which is a disadvantage of these devices.

The technical problem to which the invention is directed is the creation of a device capable of simultaneously measuring shock pulses by the resonance method to measure the amplitude of shock pulses by the broadband method, the regular value of the object vibration and the temperature at the installation site with one universal sensor.

The technical result of the invention is the possibility of a one-time measurement of the levels of low-frequency and high-frequency vibrations, as well as the temperature by a single installation of one sensor, i.e. increasing the versatility of the device.

To achieve a technical result, in a device for diagnosing equipment comprising a primary passive low-pass filter, a charge amplifier and a normalizing amplifier, a primary vibration transducer connected in series with a secondary transducer containing a first buffer stage connected to the first DC-to-DC converter, a proportional filter connected in series with the second buffer cascade and a narrow-band filter according to the invention The first buffer stage is connected in parallel with the high-pass filter and the band-pass filter, and the narrow-band filter is connected in series with the second peak detector and the average value detector.

Also, to achieve a technical result, the primary vibration transducer comprises a vibration sensitive element connected in series with a passive low-pass filter, a charge amplifier and a normalizing amplifier, to the output of which are connected a parallel-connected AC-to-current converter and an output stage.

The secondary converter normalizes the output signals thanks to an electronics unit containing a high-pass filter connected in series with the first peak detector and the second DC-to-DC converter. The band-pass filter is connected in series with an integrator, a rms detector and a third DC-to-DC converter. The second peak detector is connected in series with the first logarithm and the first buffer averaging cascade. The average value detector is connected in series with the second logarithm and the second buffer averaging cascade.

A threaded rod is made on one end surface of the primary vibration transducer, and a four-pin cylindrical connector is installed on the opposite end surface for connection with the secondary transducer, which contains an integrated spark protection barrier.

Patent studies have not identified technical solutions characterized by the claimed combination of essential features, therefore, we can assume that this invention meets the criterion of "novelty."

In addition, the present invention can be manufactured on an industrial scale using standard equipment and will find application both independently and as part of automated systems for monitoring, protection and diagnostics of industrial equipment performing rotational and reciprocating movements during its operation in the energy sector, mechanical engineering and other industries and science, that is, characterized by the criterion of "industrial applicability".

The invention is illustrated by drawings:

in FIG. 1 is a block diagram of a device;

in FIG. 2 - appearance of the primary vibration transducer;

in FIG. 3 - appearance of the secondary Converter.

A device for equipment diagnostics (measuring channel), the structural diagram of which is shown in FIG. 1 is a primary vibration transducer 2 provided with a temperature sensor 1, connected in series with a secondary transducer 3. The primary vibration transducer 2 is an inertial transducer and uses a direct piezoelectric effect. For this, a vibration sensitive element 5 is fixed in the housing 4 of the primary transducer 2 of vibration, connected in series with a passive low-pass filter 6, a charge amplifier 7 and a normalizing amplifier 8 with a programmable gain.

Passive low-pass filter 6 has a frequency response of the form:

,

,

Where:

K ₁ is the direct current filter transmission coefficient;

j is the complex unit;

ω is the circular frequency;

τ ₁ - filter time constant (50 μs <τ ₁ <100 μs).

The output of the normalizing amplifier 8 is connected in parallel to the transformer 9 of the alternating voltage into current and the output stage 10. The output stage

10, during calibration, it is possible to externally set the coefficient for the normalizing amplifier 8. The AC-to-current converter 9 provides a signal proportional to the peak value of acceleration for operation on a long line at output 11, and the output stage 10 provides normalized in frequency and amplitude output signal 12.

The vibration sensitive element 5 is made in the form of a piezoelectric bimorph 13, mounted between precision washers 14, by means of a bolt 15 made of non-magnetic steel.

The temperature sensor 1 is a temperature sensor glued to a thermally conductive compound in a cylindrical recess in the inner part of the housing 4 of the primary vibration transducer 2, next to the threaded rod 16 (see Fig. 2).

The threaded rod 16 is made on one of the end surfaces of the primary vibration transducer 2, and on the opposite end surface of the primary vibration transducer 2 there is a four-pin cylindrical connector 17 for connection with the secondary transducer 3 (see Fig. 2).

The primary vibration transducer 2 and the secondary transducer 3 are connected by a communication line 18, for example a cable, for example a twisted pair cable with a common braid (screen). The pin cylindrical connector 17 is made for soldering the wire. The primary transducer 2 vibration and the communication line 18 are connected by a threaded joint. The communication line 18 is made with a common braid (screen) both to reduce the influence of external electromagnetic radiation on the internal signal wire, and to reduce the parasitic radiation transmitted through the internal veins of the signals.

The temperature sensor 1 provides a signal proportional to the voltage at the output 19. The common wire 20, which is the ground, is connected to the housing 4.

Thus, as a result of the operation of the primary vibration converter 2, four outputs are provided: by temperature (10 mV / OS); vibration (10 μF / g) and power (15-30 V); monitoring and calibration (100 mB / g), as well as common wire.

The secondary Converter 3 contains a first buffer stage 21, connected in series with the first Converter 22 DC voltage into a current of 4-20 mA. This sequence allows you to get the output 23 signal proportional to the temperature of the diagnostic object.

The secondary converter 3 also contains a proportional filter 24, to the output of which a second buffer stage 25, a high-pass filter 26 and a band-pass filter 27 are connected in parallel.

The proportional filter 24 has a characteristic of the form:

,

,

where τ ₂ ≈ τ _{1 of the} passive low-pass filter 6 is selected, and τ ₃ is selected based on the desired upper cutoff frequency of the channel, for example, τ ₃ ≈8 μs for 20 kHz.

The high-pass filter 26 is connected in series with the first peak detector 28 and the second DC / DC converter 29 to 4-20 mA.

The bandpass filter 27 is connected in series with an integrator 30, a rms detector 31, and a third DC / DC converter 32 to 4-20 mA.

This arrangement of circuit elements allows to obtain a signal at output 33, corresponding to an alternating voltage proportional to vibration acceleration, for diagnostics and spectral analysis, as well as a signal at output 34, proportional to the peak value of the high-frequency acceleration component, and a signal at output 35, proportional to the rms value of vibration velocity.

In parallel to the proportional filter 24, a narrow-band filter 36 is connected, with a center frequency of 46 kHz, i.e. close to the resonant frequency of the vibration sensitive element 5 (width at the level of -3 dB about 3 kHz).

Sequentially, a second peak detector 37 and an average value detector 38 are coupled to the narrowband filter 36. The second peak detector 37 is connected in series with the first logarithmator 39 and the first buffer averaging stage 40. The average value detector 38 is connected in series with the second logarithmator 41 and the second buffer averaging stage 42.

This arrangement of circuit elements allows you to get a signal proportional to the technical condition of the bearing at the output 43, as well as a voltage signal proportional to the state of the bearing lubricant at the output 44. The development of a defect in the bearing leads to an increase in voltage at the output 43, and a deficiency of lubricant in the bearing leads to an increase output voltage 44.

The secondary Converter 3 normalizes the output signals and protects against interference due to shielding and complete galvanic separation between inputs, outputs and power, this is provided by the housing 45 (see Fig. 3) with an integrated spark protection barrier 46. The housing 45 is made with the possibility of mounting on a DIN rail .

When the secondary converter 3 is operated together with the primary vibration converter 2, seven outputs are provided: three 4-20 mA outputs (rms vibration velocity, peak acceleration and temperature), three resonance (shock pulses) outputs and one variable acceleration output.

Thus, the present invention allows to solve a technical problem, namely to carry out the whole complex of diagnostic measures using one universal device, a single installation on the diagnostic object.

The device for diagnosing equipment (measuring channel) during the determination of the state of the bearing works as follows: the sensitive element 5 due to its design, i.e. unloaded bimorph 13 with strictly fixed sizes and fixed between precision washers 14 has a resonance that is stable in frequency and amplitude, for example, about 46 kHz. For the simultaneous measurement of vibration, the resonance amplitude due to the passive filter 6 is reduced by approximately an order of magnitude to values at which overload of the charge amplifier does not occur for any, even significant, bearing defect. This at the same time significantly increases overload protection for high values of pre-resonance vibration, but distorts the frequency response in the pre-resonance region. To restore it, the filtered signal is fed to the input of the proportional filter 24. The proportional filter 24 restores the frequency response for vibration measurements as follows.

At the output of the proportional filter, the signal can be represented as follows:

,

,

that at τ ₂ ≈τ _{1 is} converted to:

,

,

, что, например, для τ₃≈8 мкс обеспечивает полосу 20 кГц.those. with the above ratio of time constants, the frequency response is converted to a flat frequency response with an upper cutoff frequency

, which, for example, for τ ₃ ≈8 μs provides a band of 20 kHz.

Thus, a broadband vibration measurement is provided, since the output signal of the proportional filter 24 is a signal with an already flat frequency response that is fed to the buffer stage 25 for analysis and to line 26-28-29-34 for highlighting the peak value of high-frequency vibration, as well as on line 27-30-31-32-35 to obtain an output signal proportional to vibration velocity. High-frequency acceleration output 34 can be used to confirm developed defects in bearings or gearboxes. Output 35 rms vibration speed can be used to protect and automatically stop the unit according to regulatory documents.

For simultaneous resonant monitoring of the state of the bearing, the signal is transmitted to the band-pass filter 36 to the proportional filter 24 and thus the normalized resonant signal arising at the resonance of the sensing element 5 is sent to line 37-39-40-43 to determine the technical condition of the bearing, since the development of the defect in the bearing leads to an increase in voltage at the output 43, at the same time, the normalized resonant signal arising at the resonance of the sensing element 5 is also sent to line 38-41-42-44 for bearing lubrication, since a lack of lubrication in the bearing leads to an increase in output voltage 44.

Claims (8)

1. A device for equipment diagnostics, comprising a primary vibration transducer equipped with a temperature sensor, a passive low-pass filter, a charge amplifier and a normalizing amplifier, connected in series with a secondary converter containing a first buffer stage connected to a first DC-to-DC converter, a proportional filter connected in series with a second buffer cascade, and a narrow-band filter, characterized in that the second buffer cascade is connected in parallel the high pass filter and a bandpass filter, a notch filter is connected in series with a second peak detector and the average detector. 2. A device for diagnosing equipment according to claim 1, characterized in that the primary vibration transducer comprises a vibration sensitive element connected in series with a passive low-pass filter, a charge amplifier and a normalizing amplifier, to the output of which are connected in parallel an AC-to-current converter and an output stage . 3. A device for diagnosing equipment according to claim 1, characterized in that the high-pass filter is connected in series with the first peak detector and the second DC-to-DC converter. 4. A device for diagnosing equipment according to claim 1, characterized in that the band-pass filter is connected in series with an integrator, a rms detector and a third DC-to-DC converter. 5. A device for diagnosing equipment according to claim 1, characterized in that the second peak detector is connected in series with the first logarithm and the first buffer averaging cascade. 6. A device for diagnosing equipment according to claim 1, characterized in that the average value detector is connected in series with the second logarithm and the second buffer averaging cascade. 7. A device for diagnosing equipment according to claim 1, characterized in that a threaded pin is made on one end surface of the primary vibration transducer, and a four-pin cylindrical connector for connecting to the secondary transducer is installed on the opposite end surface. 8. A device for diagnosing equipment according to claim 1, characterized in that the secondary converter contains a built-in spark protection barrier.

Images