CN109882741A - A kind of blockage of sewer detection method - Google Patents
A kind of blockage of sewer detection method Download PDFInfo
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- CN109882741A CN109882741A CN201910198231.0A CN201910198231A CN109882741A CN 109882741 A CN109882741 A CN 109882741A CN 201910198231 A CN201910198231 A CN 201910198231A CN 109882741 A CN109882741 A CN 109882741A
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Abstract
The invention proposes a kind of blockage of sewer detection methods.Testing principle of the invention: sinusoidal signal excitation is applied to tested sewer pipe outer surface in a non-contact manner by coil and measures response in receiving end；When sinusoidal signal excitation generates magnetic field B0, go out alternation vortex Δ B in sewer pipe induced inside, when there is tamper in pipeline, vortex induction generates secondary alternating magnetic field B0+ Δ B and can change, because the size of vortex is influenced by tamper conductivityσ distribution inside pipeline, therefore by detecting the variation of eddy current magnetism Δ B, byConductivityσ's distribution map of inner pipeline plug plug thing can be rebuild.The situation of change of sewer pipe internal conductance rate σ can be shown by computer, so that it is determined that the specific location of blockage of sewer.The method of the present invention includes that detection is convenient, does not need to destroy pipeline, need not be laid with detection device in advance, reduce expenses, is high-efficient, the advantages that workload is small, anti-interference strong, caters to the market demand.
Description
Technical field
The present invention relates to a kind of blockage of sewer detection field more particularly to a kind of be inconvenient to dismantle blockage of sewer
Detection method, the method can quick and precisely find line clogging position.
Background technique
With the high speed development of economic construction of China, the demand to various transport pipelines is increasing, pipeline transportation be after
The 5th kind of means of transportation occurred after traditional highway, railway, air transportion, water transport mode.With the construction of urban Underground pipeline
And development is responsible for energy delivery, the water drainage mitigation, waste row in city as the important component of urban infrastructure
The functions such as abandon, therefore, urban Underground pipeline it is normal, reliably use and run and be of great significance to city.
Currently, sewer pipe problem of management is also more and more while fast development along with underground piping, and due to ground
Urban waterlogging that lower line clogging is caused, the problems such as powering off of cutting off the water also bring strong influence to city dweller.At present
The experience that the maintenance of lower pipeline relies primarily on pipe network maintenance personnel is inspected periodically and is safeguarded, and uses artificial detection
Method detects whether sewer pipe blocks, this not only consumes a large amount of manpower, but also detection efficiency is extremely low, thus not
It is able to satisfy the growth requirement of modern city.Pipeline blockage detector is to set after pipeline laying for detecting the whether unobstructed detection of pipeline
It is standby, generally comprise sender unit and signal receiving device, signal receiving device by according to the signal strength or weakness received come
Judge the blocking position of pipeline.But reception device in the prior art lacks intuitive display, most of sound that pass through are to signal
Power is judged that, when external environment is larger due to construction noise, user is usually unable to judge accurately the size of sound, into
And it is difficult the blocked specific location of accurate judgement pipeline.With the development of science and technology, domestic and international more commonly used detection skill
There are also the methods of camera methods, the detection of pre-buried pressure sensor, Three Dimensional Ground laser scanning in ultrasonic Detection Method, pipe for art.
The present invention makes to generate alternating magnetic field B0 using additional alternating current, and equipment moves on pipeline, works as line clogging
Object is by action of alternating magnetic field and then generates vortex, and vortex generates secondary magnetic field Δ B, and the magnetic field that receiving coil receives at this time is
The magnetic field B0+ Δ B that the magnetic field and vortex of itself generate, can calculate vortex by calculating comparison and generate magnetic field Δ B, thus
The specific location of blocking can be deduced.It need not be laid with pipe testing apparatus in advance, reduction is paid wages, save budget, speed is fast, essence
The advantages that degree is high, workload is small.
Summary of the invention
For the limitation of existing detection method currently on the market, the object of the present invention is to provide a kind of structure letters
Single, algorithm is succinct and solves the detection method that blockage of sewer position cannot be accurately positioned during dredging.The present invention
Sewer pipe can be accurately found to be blocked position, on-the-spot test do not need to arrange some sensing equipments in advance, reduce engineering at
Originally, the characteristics of late detection is convenient, efficient, easy to operate, abundant information, the side for high precisely detection blockage of sewer
Method.
The present invention provides a kind of blockage of sewer detection method, this method specifically includes that excitation coil, receives line
Circle, sine signal source, power amplifier module, differential amplification module, background signal zeroing module, locking phase amplification module, A/D conversion
Module, system control module, laptop.Its basic principle is exactly: when tested pipeline is placed in alternating magnetic field B0, due to stifled
Plug thing is influenced that eddy current magnetism Δ B can be generated in its vicinity by alternating magnetic field, and the conductivity σ of tamper can interfere with vortex
Magnetic field in turn disturbs former alternating magnetic field B0, and the variable quantity that receiving coil receives magnetic field B0+ Δ B comes image study area indirectly
The conductivityσ of domain tamper, byImage reconstruction is carried out by algorithm for reconstructing appropriate to block up to reflect in Target pipe
Fill in situation.
The present invention is realized suddenly by following measured step:
Step 1: additional sine wave signal excitation makes excitation coil generate excitation field B0 by power amplifier；
Step 2: generating eddy current effect near tested pipeline tamper under the action of excitation field B0, magnetic field Δ is generated
B, it is B0+ Δ B that receiving coil, which will receive magnetic field strength, at this time.Electromagnetic field and electric current are derived further according to maxwell equation group
Relationship governing equation, and utilize integral carry out numerical value calculating；
Step 3: calculating the voltage v and conductivityσ of survey region receiving coil；
Step 4: the specific location of line clogging is calculated and be shown by computer.
Detailed description of the invention
Fig. 1 magnetic vector relation schematic diagram；
Fig. 2 pipe detection schematic diagram；
Fig. 3 pipe detection system schematic；
Specific embodiment
Excitation coil loads simple alternating current electric signal first, and excitation coil is close at a distance from receiving coil, in excitation frequency
In the identical situation of rate, the inductive signal that receiving coil detects is very strong, and eddy current field E can be indicated are as follows:
E=-jwA- ▽ φ (1.1)
Wherein w is angular frequency, and A indicates that magnetic vector potential, φ indicate electric scalar potential.
From (1.1) it can be seen that eddy current field has 2 kinds of sources: (1) magnetic field changed over time generates electric field；(2) medium
The variation of surface profile and volume can also generate electric field.Magnetic vector potential A is made of two components, the master drive magnetic that excitation coil generates
Field magnetic vector potential APThe secondary magnetic field A generated with eddy current fieldSAccording to following three equation:
It is available :=0 (1.5) ▽ (j+jw ε E)
Jw ε E in above formula is displacement current density, and the differential form of Ohm's law: j=σ E and (1.1) is substituted into
(1.5) available:
▽ [(σ+j ω ε) ▽ φ]=j ω A ▽ σ (σ+j ω ε) R (1.6)
The condition that exterior normal direction n component according to dielectric surface electric current is zero,
That is: the component of the n of E=-j ω A- ▽ φ is zero, the boundary condition of available formula (1.6):
In order to simplify problem: the magnetic vector potential A that main field generates when (1) without measured objectPIt is equal with magnetic vector potential A；(2) it does not examine
Consider displacement current.According to above (1), (2), by magnetic vector potential A APInstead of；Formula (1.7) and formula (1.6) are reduced to following two etc.
Formula, scalar φ can be obtained by solving following difference equation:
The φ in two formulas can be decomposed into real and imaginary parts two parts above, use φ respectivelyR、φIIt indicates:
The equation of real part:
Imaginary part equation group:
By real part equation group it can be seen that φR=0, so scalar φ only has imaginary.
Therefore eddy current field can indicate are as follows: E=-j (ω Ap-▽φ) (2.4)
Induced current density J in mediumiAs σ E.
Magnetic induction signal strength in receiving coil is divided into two parts: a part is that the exciting current in excitation coil generates
Magnetic induction density BP, another part is the Secondary Disturbance magnetic field strength B that the vortex in testee generatesS.That is receiving coil magnetic
Field intensity B=BP+BS, BPSubstantially fixed, the variation of the magnetic induction intensity in receiving coil is equal to BSVariation, i.e. B=BS。
According to Biot -- Sa cuts down your law:
R is the vector at source point any point into measured object in formula.Determine the variation ▽ B of receiving coil magnetic induction intensityS
With the relationship of object conductivity variations ▽ σ, when object conductivity is respectively what σ of σ0When, magnetic induction intensity is B respectivelySAnd BS0, with
φ0+ Δ φ, σ0+ ▽ σ replaces the φ and σ in formula (2.5), obtains:
Above formula is substituted into Δ Bs=Bs-Bso, ignore last in above formula second-order differential variable, be used in combinationInstead of
▽ (▽ φ), can obtain following Δ BsWith the corresponding relationship of conductivity variations Δ σ:
Above formula describes measured object conductivity variations and contacts with changes of magnetic field in receiving coil, in the actual measurement,
It is variation that detection system, which obtains induced electromotive force in receiving coil, so also needing to derive receiving coil magnetic induction electromotive force
Variation and conductivity variations between relationship.According to the reciprocal theorem in magnetic field, the magnetic flux of receiving coil are as follows:
In formula: IRFor the reciprocity electric current in receiving coil, ARFor IRThe magnetic potential of generation, j include exciting current density JR, sense
Answer current density, Ji,ITFor the electric current of excitation coil；According to electromagnetic induction theorem v=-jw φ and
ATFor excitation coil magnetic field, the induced voltage of receiving coil is obtained are as follows:
For receiving coil using differential type detection structure, i.e., the Same Name of Ends of two coils is opposite, receiving coil and excitation
The distance of coil is identical and direction of winding is on the contrary, the inductive signal for the main field that two such receiving coil detects is identical and anti-
To output signal does not just include the inductive component of main field, at this time receiving coil output voltage are as follows:
Wherein: AR1、AR2The magnetic potential that respectively two receiving coil reciprocity electric currents generate, IR1、IR2Respectively two reception lines
Reciprocity electric current in circle, similarly, according to Δ BsWith the available testee conductivity of derivation process and the receiving coil electricity of Δ σ
The relationship of pressure:
Make excitation coil generate alternating magnetic field by amplifier after being loaded with sine wave signal on excitation coil, works as magnetic
When field passes through the tamper in tested pipeline, tamper and Near Pipelines generate vortex, and the secondary magnetic field of this vortex generation is counter to be made
For main field, the variation occurred by detection magnetic field, receiving coil detects magnetic flux change again by difference amplifier and lock
Phase amplifier amplifies it, then so that information current is transferred to computer by A/D converter, and pipeline is obtained by calculation
Distribution of conductivity；Judge whether pipeline blocks according to the case where conductivity variations.
Claims (3)
1. a kind of blockage of sewer detection method, the method includes at least following steps:
Step 1: external circuit loads sine wave exciting signal, then excitation coil is made to generate excitation field by power amplifier
B0；
Step 2: generating vortex around tested pipeline under the action of excitation field B0, will be generated according to faraday's theorem vortex
Magnetic field Δ B, the magnetic field strength received is B0+ ▽ B by receiving coil at this time, and wherein ▽ B and B0 have following relationship:
P is tested pipeline geometric constant, ε0For the dielectric constant in space, εrFor the dielectric constant of measured object, σ is measured object conductance
Rate, j are current density；Eddy current field E can be indicated are as follows: wherein w is angular frequency to E=-jwA- Δ φ, and A indicates magnetic vector potential, φ table
Show that electric scalar potential, ▽ are gradient factor；The relationship governing equation of electromagnetic field and electric current is derived further according to maxwell equation group:
By: ▽ D=ρ can be derived: D=ε E, by Current continuity equation: ▽ j=-jw ρ
It derives: ▽ (j+jw ε E)=0
Jw ε E in above formula is displacement current density, and ρ is that electricity Xiang Midu, D are electric displacement vector, and H is magnetic field strength, and ε is dielectric
Constant, ▽ are gradient factor, and B is magnetic induction intensity；The differential form of Ohm's law: j=σ E is updated to Maxwell side
It is available in journey:
▽ [(σ+j ω ε) ▽ φ]=j ω A ▽ σ (σ+j ω ε) R；
Step 3: the voltage v and conductivityσ of survey region receiving coil are calculated, the magnetic that main field generates when (1) is without tamper
Vector potential ApAnd have magnetic vector potential A when tamper equal, (2) do not consider displacement current；
It can be by magnetic vector potential A A according to (1), (2)pInstead of being reduced to following two formulas, scalar φ is by solving following difference side
Journey obtains:
According to electromagnetic induction theorem v=-jw φ, andATFor excitation coil magnetic field, received
The induced voltage of coil are as follows:
IRFor the reciprocity electric current in receiving coil, ITFor the electric current of excitation coil, ARFor IRThe magnetic potential of generation.
2. blockage of sewer detection method according to claim 1, it is characterised in that:
Excitation coil and receiving coil are around on the same axis, and excitation coil and receiving coil be at a distance of very little, so in excitation frequency
In the identical situation of rate, the inductive signal that receiving coil detects can be very strong, is very suitable for practical operation.
3. blockage of sewer detection method according to claim 1, it is characterised in that: receiving coil is examined using differential type
The Same Name of Ends of geodesic structure, i.e., two coils is opposite, and receiving coil is identical at a distance from excitation coil and direction of winding is on the contrary, two
Receiving coil detects that the inductive signal size of main field is identical and direction is reversed, and output signal does not just include the induction of main field
Component, at this time detection coil output voltage are as follows:
Wherein, AR1、AR2The magnetic potential that respectively two receiving coil reciprocity electric currents generate, IR1、IR2In respectively two receiving coils
Reciprocity electric current, σ0Initial conductivity,Initial electric scalar potential, BSFor eddy current magnetism intensity；Testee conductivity and reception line
Enclose the relationship of voltage:
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111594766A (en) * | 2020-04-17 | 2020-08-28 | 中国矿业大学 | Pipeline detection system and detection method |
| CN112666395A (en) * | 2020-12-17 | 2021-04-16 | 蒋峰 | Non-contact metal material conductivity measurement method and system |
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| CN102797979A (en) * | 2012-08-29 | 2012-11-28 | 上海海事大学 | Device for detecting leakage points of underground pipeline and method thereof |
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| CN108267454A (en) * | 2018-01-30 | 2018-07-10 | 中国计量大学 | The defects of applied to retaining pressure fluid inside pipe fitting measurement and positioning system and method |
| CN108474521A (en) * | 2015-11-02 | 2018-08-31 | 柔性钢管道技术公司 | The real-time integrity of land pipelines monitors |
| CN208013100U (en) * | 2018-01-30 | 2018-10-26 | 中国计量大学 | A kind of device measured for retaining pressure fluid pipe fitting positioned internal |
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2019
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Patent Citations (7)
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| CN101749543A (en) * | 2008-12-10 | 2010-06-23 | 东北大学 | Vortex flux leakage position indicator and control method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111594766A (en) * | 2020-04-17 | 2020-08-28 | 中国矿业大学 | Pipeline detection system and detection method |
| CN112666395A (en) * | 2020-12-17 | 2021-04-16 | 蒋峰 | Non-contact metal material conductivity measurement method and system |
| CN112666395B (en) * | 2020-12-17 | 2024-05-31 | 无锡学院 | Non-contact metal material conductivity measurement method and system |
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Application publication date: 20190614 |