Long-distance eddy current detection probe

Abstract

The invention relates to the technical field of nondestructive testing, and discloses a long-distance eddy current testing probe, the long-distance eddy current testing probe comprises a cable assembly and a probe assembly, the probe assembly is connected to the far end of the cable assembly, and the probe assembly comprises a coil assembly, a pre-amplifier, a power supply conversion module and a signal shunt module. The pre-amplifier is connected to the coil assembly to amplify a detection signal; and the power supply conversion module is used for converting an excitation signal of the eddy current instrument into a bipolar direct-current power supply and supplying power to the pre-amplifier. Based on the compatibility of the excitation signal of the eddy current instrument and the pre-amplifier of the eddy current sensor in power parameters, an excitation signal multiplexing power supply method is adopted, an extra power line is avoided, and the problems of signal attenuation compensation and power supply in long-distance eddy current detection are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing, and particularly to a remote eddy current testing probe. Background Art

[0002] As an important non-destructive testing method, eddy current testing technology faces special challenges in remote testing scenarios. For example, in the inspection of nuclear power plant pressure vessels, inspectors need to remotely operate the probe through a cable longer than 20 meters in the radiation safety area; in the inspection of oil and gas pipelines, the detection device needs to use a cable longer than 50 meters to transmit signals to the ground receiving equipment; in the in-service inspection of aircraft blades, due to the complex and narrow space structure of the turbine compartment and the requirements of in-situ inspection, a cable longer than 30 meters is required to send the inspection probe to the inspection location for inspection.

[0003] The main technical problems faced in the above application scenarios are: the standard cable length of conventional eddy current testing probes (about 10 meters) is difficult to meet the requirements of remote testing, and the cable needs to be extended, that is, there is a problem of compensating for signal transmission attenuation over long distances. Usually, when the transmission distance exceeds 15 meters, the signal-to-noise ratio of the conventional detection system will decrease by more than 40%. The existing solution is to add a pre-amplification unit at the sensor end to increase the effective signal amplitude, but this leads to a new engineering contradiction - the power supply problem of the pre-amplification unit. The current practice is to add an independent power supply lead in the cable, and such cables are expensive (at least 20 yuan / meter), while the cost of conventional cables is only about 7 yuan / meter, which significantly increases the total cost of the probe. At the same time, as a high-loss component, the eddy current probe further leads to a significant increase in the overall application cost. This has greatly affected the development and popularization of eddy current testing technology. Therefore, there is an urgent need for an innovative probe solution in this field that can not only ensure the quality of long-distance signal transmission but also effectively solve the power supply problem of remote electronic devices. Summary of the Invention

[0004] To solve the above problems, the present invention provides a remote eddy current testing probe, and the present invention is implemented as follows:

[0005] A remote eddy current testing probe, where the remote eddy current testing refers to a situation where the distance between the eddy current testing equipment and the part to be inspected is relatively far, and a long cable is required to connect the eddy current sensor to the eddy current instrument to complete the testing. The remote eddy current testing probe includes:

[0006] A cable assembly;

[0007] A probe assembly, which is connected to the distal end of the cable assembly and includes:

[0008] A coil assembly;

[0009] A pre-amplifier, which is connected to the coil assembly to amplify the detection signal;

[0010] A power conversion module, which is used to convert the excitation signal of the eddy current instrument into a bipolar DC power supply and supply power to the preamplifier;

[0011] A signal splitting module, including:

[0012] The main path of the excitation signal and the branch path of the excitation signal, where

[0013] The main path of the excitation signal is connected to the coil assembly, and the branch path of the excitation signal is connected to the power conversion module.

[0014] Furthermore, the cable assembly adopts a three-wire coaxial structure, including:

[0015] The excitation signal transmission line, the detection signal transmission line, and the common ground shielding layer.

[0016] Furthermore, the coil assembly includes:

[0017] An excitation coil, which is connected to the excitation signal transmission line;

[0018] A detection coil, which is connected to the detection signal transmission line.

[0019] The common ground shielding layer contacts the part to be detected through a conductive spring at the probe assembly end to form an electromagnetic shielding loop.

[0020] The power conversion module includes:

[0021] A rectification module, which rectifies the excitation signal input to the branch path of the excitation signal in the full waveband;

[0022] A filtering module, which uses an LC circuit to smooth the pulsating waveform after rectification;

[0023] A voltage stabilizing module, which outputs stable positive and negative DC voltages.

[0024] Alternatively, the cable assembly adopts a single-strand cable structure, which is the excitation signal transmission line, and the probe assembly further includes a wireless module, and the detection signal is transmitted to the eddy current instrument wirelessly.

[0025] Furthermore, the power conversion module further includes an isolation circuit, which is used to prevent the noise of the bipolar DC power supply from interfering with the excitation signal reversely.

[0026] Compared with the prior art, based on the compatibility of the excitation signal of the eddy current instrument and the preamplifier of the eddy current sensor in terms of power parameters, the present invention proposes a method for multiplexing the power supply of the excitation signal, that is, the excitation signal output by the eddy current instrument is not only used to excite the eddy current sensor, but also used to provide power for the preamplifier of the eddy current sensor, avoiding additional power lines, and effectively solving the problems of signal transmission attenuation compensation and power supply in long-distance eddy current detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following briefly introduces the drawings required for use in the description of the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is the equivalent circuit schematic diagram of a traditional eddy current sensor.

[0029] Figure 2 It is the schematic diagram of an eddy current sensor with a preamplifier.

[0030] Figure 3 It is the schematic diagram of the excitation signal multiplexing power supply long-distance eddy current detection probe according to the embodiment of the present invention.

[0031] Figure 4 It is a schematic diagram of a long-distance eddy current detection working condition.

[0032] Figure 5 It is a schematic diagram of the brief structure of a long-distance eddy current detection probe.

[0033] In the figure:

[0034] 10 - Cable assembly;

[0035] 20 - Probe assembly, 21 - Coil assembly, 22 - Preamplifier, 23 - Power conversion module, 24 - Signal splitting module, 25 - Wireless module;

[0036] 30 - Long pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention.

[0038] In the description of the present invention, the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0039] The long-distance eddy current testing in the present invention refers to the situation where the distance between the eddy current testing device and the part to be tested is relatively far. In this case, a long cable is required to connect the eddy current sensor to the eddy current instrument to complete the testing. The application scope of long-distance eddy current testing is very wide. For example, in the field of ocean engineering, it is used for the detection of submarine pipelines; in the petrochemical industry, it is used for the detection of heat exchange pipelines in oil and gas transmission pipelines and various chemical equipment; in power plants, it is used for the detection of steam pipelines, condenser tubes, etc.; in the aerospace field, in the detection of aircraft structural components, such as long-distance eddy current testing of parts like wings, fuselages, engines, etc.

[0040] Reference attached Figures 1-3 To solve the problem of the attenuation of the backhaul signal in long-distance eddy current testing in the above-mentioned working conditions and the power supply problem after adding a signal amplification element at the probe end, based on the compatibility of the excitation signal of the eddy current instrument and the preamplifier of the eddy current sensor in power parameters, the present invention proposes a method for reusing the excitation signal for power supply, that is, the excitation signal output by the eddy current instrument is not only used to excite the eddy current sensor, but also used to provide power for the preamplifier of the eddy current sensor, avoiding an additional power cord. Based on this method, the probe structure is designed, and special cable components and probe components are set. Among them, a preamplifier, a power conversion module, and a signal splitting module are added to the probe component. The power conversion module converts the excitation signal of the eddy current instrument into a bipolar DC power supply to supply power to the preamplifier. Further, an isolation circuit is set to prevent the noise of the bipolar DC power supply from interfering with the excitation signal in the reverse direction. The specific embodiments are as follows:

[0041] Embodiment 1

[0042] This embodiment is applied to the detection of submarine pipelines. The detection of submarine pipelines is an important link to ensure the safety of ocean resource development and transportation. The long-distance eddy current testing probe can be used to perform long-distance detection on the outer wall of the submarine pipeline through an underwater robot or other underwater detection equipment.

[0043] The long-distance eddy current testing probe described above includes a cable assembly 10 and a probe assembly 20. The probe assembly 20 is connected to the distal end of the cable assembly 10 and includes a coil assembly 21, a preamplifier 22, a power conversion module 23, and a signal splitting module 24.

[0044] The preamplifier 22 is connected to the coil assembly 21 to amplify the detection signal;

[0045] The power conversion module 23 is used to convert the excitation signal of the eddy current instrument into a bipolar DC power supply and supply power to the preamplifier 22;

[0046] The signal splitting module 24 includes a main excitation signal path and a branch excitation signal path. Among them, the main excitation signal path is connected to the coil assembly 21, and the branch excitation signal path is connected to the power conversion module. In this embodiment, the signals split into the main excitation signal path and the branch excitation signal path are frequency-separated. The excitation signal emitted by the eddy current instrument can be a single-frequency or multi-frequency excitation signal. Among them, the power of the signal split into the branch excitation signal path remains constant, and the signal split into the main excitation signal path changes correspondingly with the change of the frequency of the excitation signal emitted by the eddy current instrument.

[0047] By designing an eddy current detection probe that uses excitation signal multiplexing for power supply, the long-distance eddy current detection probe does not require an additional power cord, making the system wiring more concise, energy-efficient, reducing the difficulty and risk of underwater wiring. The characteristics of high integration and adaptability to complex environments enable it to work stably in harsh environments such as deep sea high pressure, low temperature, and strong corrosion.

[0048] Furthermore, the cable assembly adopts a three-wire coaxial structure, including an excitation signal transmission line, a detection signal transmission line, and a common ground shielding layer. The outside of the cable assembly is coated with a waterproof and corrosion-resistant flexible sleeve. The excitation signal transmission line is used to transmit the excitation signal emitted by the detection instrument, the detection signal transmission line is used to transmit the detection signal obtained by the detection coil, and the common ground shielding layer contacts the part to be detected through a conductive spring at the probe assembly end to form an electromagnetic shielding loop. In this embodiment, it can be made of a metal material with high conductivity to isolate external electromagnetic interference signals.

[0049] Furthermore, the coil assembly includes an excitation coil and a detection coil. The excitation coil is connected to the excitation signal transmission line, and the detection coil is connected to the detection signal transmission line: According to the material and detection requirements of the submarine pipeline, the coil assembly is optimized, and superconducting materials with high temperature and high pressure resistance are used to make the coil to improve the sensitivity and stability of the coil. At the same time, a magnetic material with high magnetic permeability can also be used as the coil skeleton to enhance the focusing and transmission efficiency of the magnetic field.

[0050] The power conversion module includes a rectification module, a filtering module, and a voltage stabilization module:

[0051] The rectification module performs full-band rectification on the excitation signal input to the branch excitation signal path; the rectification module can adopt a rectifier bridge composed of high-performance rectifier diodes, which can completely convert the AC excitation signal into a DC signal and provide a stable DC basis for subsequent circuit processing.

[0052] The filter module uses an LC circuit to smooth the pulsating waveform after rectification; the filter circuit composed of an inductor (L) and a capacitor (C) effectively smooths the pulsating components in the rectified DC signal by utilizing the inductor's blocking effect on current conversion and the capacitor's charging and discharging characteristics. When the current changes, the inductor generates a reverse electromotive force to hinder the current change, while the capacitor charges and discharges when the voltage fluctuates, making the output DC signal more stable and reducing voltage fluctuations and noise.

[0053] The voltage stabilizing module outputs stable positive and negative DC voltages. An integrated voltage stabilizing chip, such as a linear voltage stabilizing chip or a switching voltage stabilizing chip, is used to further process the filtered DC signal. The voltage stabilizing chip can automatically adjust the output voltage according to the changes in the input voltage and load to ensure that the output positive and negative DC voltages are stable within the operating voltage range required by the preamplifier. At the same time, the voltage stabilizing module also has overvoltage protection and overcurrent protection functions. When the input excitation signal is abnormal, resulting in an excessively high output voltage or an excessively large current, the power supply can be quickly cut off to protect the preamplifier and other circuit components from damage.

[0054] In this embodiment, the long-distance eddy current detection probe is installed on an underwater robot or other underwater detection equipment. The underwater robot moves along the submarine pipeline according to the preset detection path, and transmits the real-time detection data back to the control center. When the detection probe approaches the submarine pipeline, the eddy current instrument sends an excitation signal. Through the signal branch module, part of the excitation signal is transmitted to the excitation coil in the coil assembly through the main excitation signal path, generating an alternating magnetic field on the surface of the pipeline, and the other part is transmitted to the power conversion module through the excitation signal branch. The power conversion module converts the voltage into a stable positive and negative DC voltage through rectification, filtering, and voltage stabilization to power the preamplifier. During detection, when the detection coil in the coil assembly detects the change in the magnetic field caused by the pipeline defect, a detection signal is generated. After the signal is amplified by the preamplifier integrated at the probe end, it is transmitted back to the control center of the detection instrument through the cable assembly.

[0055] Furthermore, for detection environments where there are many electromagnetic interference sources, in order to improve the anti-interference ability of the detection probe, it is preferred to add multiple shielding layers to the power conversion module and the preamplifier, use shielded twisted pair cables as signal transmission lines, and add electromagnetic interference filters to the circuit to suppress the influence of external electromagnetic interference on the detection signal.

[0056] Embodiment 2

[0057] Reference Figures 4-5, in another embodiment of the present invention, the cable assembly 10 adopts a single-strand cable structure, which is an excitation signal transmission line. The probe assembly 20 further includes a wireless module 25, and the detection signal is transmitted to the eddy current instrument wirelessly. The structure of the single-strand cable has lower resistance and inductance, which can effectively reduce the energy loss of the excitation signal during transmission, ensuring that the excitation signal output by the eddy current instrument can be stably and efficiently transmitted to the probe assembly. The wireless module is integrally installed in the probe assembly and is responsible for transmitting back the signal amplified by the preamplifier.

[0058] This embodiment is applicable to the case where the wireless signal transmission effect is good, such as Figure 4 in-pipe detection in a long pipeline or detection of aero-engine components as described in

[0059] and other working conditions with less obstruction to wireless signal transmission. The wireless communication module can adopt advanced wireless communication technologies such as Bluetooth Low Energy (BLE), Wi-Fi, or ZigBee. By further streamlining the structure and improving the system integration, the system structure is simplified, making the eddy current detection system smaller in volume and lighter in weight, and improving the integration and portability of the system.

[0060] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A long-distance eddy current detection probe. Long-distance eddy current detection is when the distance between the eddy current detection equipment and the part to be detected is far, and a long cable is needed to connect the eddy current sensor to the eddy current instrument to complete the detection, characterized in that: Long-range eddy current testing probes include: Cable assemblies; A probe assembly, connected to the distal end of the cable assembly, comprises: Coil assembly; a preamplifier connected to the coil assembly to amplify the detection signal; A power conversion module, which is used to convert the excitation signal of the eddy current instrument into a bipolar DC power supply and supply power to the preamplifier; Signal splitter module, including: The excitation signal main circuit and the excitation signal branch circuit, wherein: The excitation signal main circuit is connected to the coil assembly, and the excitation signal branch circuit is connected to the power conversion module.

2. A long-distance eddy current detection probe according to claim 1, characterized in that: The cable assembly adopts a three-wire coaxial structure, including: Excitation signal transmission line, detection signal transmission line, and common ground shielding layer.

3. A long-distance eddy current detection probe according to claim 1, characterized in that: The cable assembly adopts a single-strand cable structure, which is an excitation signal transmission line. The probe assembly also includes a wireless module, and the detection signal is transmitted to the eddy current instrument in a wireless manner.

4. A long-distance eddy current detection probe according to claim 2, characterized in that: The coil assembly comprises: an excitation coil connected to the excitation signal transmission line; A detection coil is connected to the detection signal transmission line.

5. A long-distance eddy current detection probe according to claim 2, characterized in that: The common ground shielding layer contacts the part to be detected through the conductive spring at the end of the probe assembly to form an electromagnetic shielding loop.

6. A long-distance eddy current detection probe according to claim 2 or 3, characterized in that: The power conversion module comprises: A rectifier module, which performs full-band rectification on the excitation signal input by the excitation signal branch; The filter module uses an LC circuit to smooth the pulsating waveform after rectification; The voltage regulator module outputs stable positive and negative DC voltage.

7. A long-distance eddy current detection probe according to claim 6, characterized in that: The power conversion module also includes an isolation circuit for preventing the bipolar DC power supply noise from reversely interfering with the excitation signal.

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