CN102564710B - Identifying method for direct and reflected ultrasonic signals of compressed air leakage - Google Patents
Identifying method for direct and reflected ultrasonic signals of compressed air leakage Download PDFInfo
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- CN102564710B CN102564710B CN201210000139.7A CN201210000139A CN102564710B CN 102564710 B CN102564710 B CN 102564710B CN 201210000139 A CN201210000139 A CN 201210000139A CN 102564710 B CN102564710 B CN 102564710B
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Abstract
The invention belongs to the pneumatic system leak testing field. An identifying method for direct and reflected ultrasonic signals of compressed air leakage is achieved. The invention mainly relates to a method for indentifying the direct and reflected ultrasonic signals through frequency spectrum of signals, which is applied to a leakage acoustic emission detection device. The identifying method includes steps of analyzing the spectrum of the ultrasonic signals of compressed air leakage detected by the leakage acoustic emission detection device, extracting a difference feature of the direct and reflected signals on the frequency spectrum, calculating the numerical value index reflecting the difference feature, and accordingly indentifying the reflected leakage ultrasonic signals. Compared with other leakage detection devices of a compressed air system, the leakage acoustic emission detection device using the identifying method can effectively identify the reflected signals and reduce interference of reflection to positioning of a leakage point.
Description
Technical field
The invention belongs to pneumatic system Leak Detection field, relate to being applied in and leak on acoustic emission detection apparatus, the method that direct projection and reflected ultrasonic are carried out to identification.
background technology
The detection of compressed air leakage and the location of leakage point are the gordian techniquies of energy-saving field of pneumatic, utilize and leak acoustic emission testing technology, by the ultrasonic signal that detects the generation of compressed air leakage position, can locate rapidly leakage point.
Due to pneumatic site environment complexity, the leakage ultrasonic signal that checkout equipment receives may disturb the location generation of leakage point through the reflection of on-the-spot various reflectings surface, and existing acoustic emission leakage detection equipment is not tackled the measure of this kind of reflection interference.For this situation, the discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection that the present invention proposes is the identification reflected signal effectively, reduces the interference of reflection to leak point positioning.
Summary of the invention
purpose of the present inventionbe: a kind of discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection is provided.
technical scheme of the present inventionbe:
1. at first the output signal of leaking acoustic emission detection apparatus is carried out to filtering, sampling, the processing such as windowing and quick FFT conversion obtain the amplitude versus frequency characte of signal, a section (the normally 35KHz to 50KHz) that selects useful signal to concentrate;
2. calculate the center of gravity of concentrated section amplitude frequency curve and the figure that transverse axis surrounds of useful information, the horizontal ordinate of center of gravity is defined as the upper limit of low-frequency range frequency;
3. from the center of gravity horizontal ordinate, get successively n window of suitable length left, spectrum amplitude mean value Y (i) expression formula of calculating in the frequency window is:
The frequency range that wherein len is selected window, the number that n is window, y (f) is each Frequency point amplitude in window;
4. the coefficient Flu expression formula of low-frequency fluctuation trend is:
Wherein N is for Y (i+1) occurring > Y (i) (i=1,2 ..., number of times n-1), constant coefficient R (r) suitably chooses according to different frequency ranges, the reflex components of Flu value reflected signal, its value is larger, and reflex components is just more;
5. the expression formula of concentration degree Con is:
Wherein Acen is the spectral magnitude sum in the suitable frequency band in one of left and right of frequency spectrum area center of gravity (2KHz left and right), Atot be the interior spectral magnitude in above-mentioned set of signals stage casing (35KHz to 50KHz) and, the constant coefficient of T for suitably choosing, the direct projection composition of Con value reflected signal, its value is larger, and the direct projection composition is just more;
6. identifying index REF:
When REF is larger, the principal ingredient in signal is reflection,
When REF is placed in the middle, in signal, reflection quite is called mixed penetrating with the direct projection composition,
When REF hour, the principal ingredient in signal is direct projection.
advantage of the present inventionbe: compare with other compressed air system leakage detection equipment, utilize leakage acoustic emission detection apparatus of the present invention identification reflected signal effectively, reduce the interference of reflection to leak point positioning.
The accompanying drawing explanation
Fig. 1 is signal recognition method flow of the present invention.
Embodiment
Below the present invention is further illustrated.
Above-mentioned signal recognition method flow can be summarized as:
1, the A/D of signal conversion and time-frequency conversion obtain amplitude versus frequency characte;
2, calculate the coefficient Flu of reflection low-frequency fluctuation trend, calculate the coefficient Con of reflection amplitude-frequency area under spectrum concentration degree;
3, the difference of the two obtains identifying index REF.
Claims (4)
1. the discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection, it is characterized in that: utilize and leak the amplitude frequency curve of signal on the certain frequency section that acoustic emission detection apparatus detects, definition concentrated section of useful information, according to the data definition low-frequency range of concentrating section, based on the low-band signal data, calculate low-frequency fluctuation trend coefficient
Wherein, Y (r) is for from the barycenter of frequency spectrum horizontal ordinate, get successively n window of suitable length left, the spectrum amplitude mean value calculated in the frequency window, N is for Y (r+1) occurring > Y (r) (r=1,2 ... n-1) number of times, the weight of R (r) for suitably choosing according to different frequency ranges;
The number of reflex components in the value reflected signal of Flu;
The definitions set moderate,
Wherein Acen is the spectral magnitude sum in the suitable frequency band in one of about frequency spectrum area center of gravity, Atot be useful signal concentrate in section spectral magnitude and, the constant coefficient of T for suitably choosing;
The number of direct projection composition in the value reflected signal of Con;
The definition identifying index,
When REF is larger, the principal ingredient in signal is reflection,
When REF is placed in the middle, in signal, reflection quite is called mixed penetrating with the direct projection composition,
When REF hour, the principal ingredient in signal is direct projection.
2. a kind of discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection according to claim 1 is characterized in that: the frequency range that concentrated section of useful information is 35 to 50KHz.
3. a kind of discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection according to claim 1, it is characterized in that: calculate the center of gravity of concentrated section amplitude frequency curve and the figure that transverse axis surrounds of useful information, the horizontal ordinate of center of gravity is defined as the upper limit of low-frequency range frequency.
4. a kind of discrimination method to the direct projection of compressed air leakage ultrasonic signal and reflection according to claim 1 is characterized in that: the suitable frequency band in frequency spectrum area center of gravity left and right is 2KHz.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210000139.7A CN102564710B (en) | 2012-01-03 | 2012-01-03 | Identifying method for direct and reflected ultrasonic signals of compressed air leakage |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210000139.7A CN102564710B (en) | 2012-01-03 | 2012-01-03 | Identifying method for direct and reflected ultrasonic signals of compressed air leakage |
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| CN102564710A CN102564710A (en) | 2012-07-11 |
| CN102564710B true CN102564710B (en) | 2014-01-08 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1042997A (en) * | 1989-12-03 | 1990-06-13 | 山西省机械设计研究所 | Supersonic detection method for welding seams on hollow balls of lattice steel structure |
| JPH11258172A (en) * | 1998-03-10 | 1999-09-24 | Hoya Corp | Method and apparatus for inspection of heterogeneity of translucent substance |
| JP2002206984A (en) * | 2000-11-08 | 2002-07-26 | Matsushita Refrig Co Ltd | Ultrasonic leak detector for heat exchanger |
| CN101236180A (en) * | 2007-01-29 | 2008-08-06 | 天津诚信达金属检测技术有限公司 | Ultrathin wall sootblower outer sleeve weld joint ultrasound detection method |
-
2012
- 2012-01-03 CN CN201210000139.7A patent/CN102564710B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1042997A (en) * | 1989-12-03 | 1990-06-13 | 山西省机械设计研究所 | Supersonic detection method for welding seams on hollow balls of lattice steel structure |
| JPH11258172A (en) * | 1998-03-10 | 1999-09-24 | Hoya Corp | Method and apparatus for inspection of heterogeneity of translucent substance |
| JP2002206984A (en) * | 2000-11-08 | 2002-07-26 | Matsushita Refrig Co Ltd | Ultrasonic leak detector for heat exchanger |
| CN101236180A (en) * | 2007-01-29 | 2008-08-06 | 天津诚信达金属检测技术有限公司 | Ultrathin wall sootblower outer sleeve weld joint ultrasound detection method |
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| CN102564710A (en) | 2012-07-11 |
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Address after: 100191 room A506, computer building, No. 38, Xueyuan Road, Beijing, Haidian District, China Patentee after: Beijing Aisuo energy Polytron Technologies Inc Address before: 100191 room A506, computer building, No. 38, Xueyuan Road, Beijing, Haidian District, China Patentee before: Beijing ECOSO Technology Development Co., Ltd. |