Directional detection device and directional detection method for electromagnetic induction

Abstract

The invention provides an electromagnetic induction directional detection device and a directional detection method. The directional detection device comprises a transmitting device, a receiving device, a solenoid and a receiving wire assembly, the solenoid is connected with the transmitting device, the receiving wire assembly is located on the upper portion or the lower portion of the solenoid, the receiving wire assembly comprises a first receiving wire and a second receiving wire which are distributed in an orthogonal mode, and the first receiving wire and the second receiving wire are both connected with the receiving device. The primary field magnetic flux of the solenoid in a loop cavity formed by the first receiving wire and the second receiving wire is zero. According to the invention, the primary field intensity provided by the transmitting device can be enhanced, and positioning detection of the low-resistance body in the to-be-detected area is realized.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic induction technology, and in particular to an electromagnetic induction directional detection device and a directional detection method. Background Art

[0002] At present, in the field of resources and engineering geophysical exploration, there are many geophysical exploration methods and devices based on the principle of electromagnetic induction and they are widely used, especially the transient electromagnetic method. Transient electromagnetic exploration can help solve the problem of shallow detection, but when the detection operation probe is located in a limited space in the well, the signal received by the receiving device of the transient electromagnetic instrument will not only be affected by external interference, but also because of the superposition of mutual inductance between the transceiver and the transceiver, resulting in low resolution; at the same time, due to the isotropy of the transceiver coil to the surrounding anomalies, it is a world-recognized problem to achieve fine interpretation and directional detection of electromagnetic exploration. Therefore, as a transient electromagnetic method in the well, new technical attempts and breakthroughs are needed to eliminate the near-field mutual inductance effect of the transceiver and the transceiver sensor and the directional detection of hidden targets.

[0003] The invention with publication number CN116224448A discloses an electromagnetic induction detection method and system, which provides a primary field through a grounded straight wire and uses a dual-channel orthogonal coil as a receiving device. However, the number of turns of the grounded straight wire cannot be increased, so that the primary field provided is very limited; at the same time, its grounding current will also affect the accuracy of detection. Summary of the invention

[0004] The purpose of the present invention is to solve the defects in the prior art and provide an electromagnetic induction directional detection device and a directional detection method, which can enhance the primary field strength provided by the transmitting device and realize the positioning detection of low-resistance bodies in the area to be detected.

[0005] To achieve the above object, the present invention provides an electromagnetic induction directional detection device, comprising a transmitting device, a receiving device, a solenoid and a receiving wire assembly;

[0006] The solenoid is connected to the transmitting device, the receiving wire assembly is located at the upper part or the lower part of the solenoid, the receiving wire assembly includes a first receiving wire and a second receiving wire that are orthogonally distributed, the first receiving wire and the second receiving wire are both connected to the receiving device, and the primary field magnetic flux of the loop cavity formed by the solenoid and the first receiving wire and the second receiving wire is zero.

[0007] During use, the solenoid is first connected to the transmitting device; secondly, the first receiving wire and the second receiving wire are both connected to the receiving device; then the electromagnetic induction directional detection device is placed in the borehole in the area to be detected, and the power of the transmitting device is turned on; after a period of time, the power is turned off, and according to Faraday's law of electromagnetic induction, the low-resistance body in the area to be detected will form eddy currents inside, generating a secondary magnetic field that decays with time and is received by the first receiving wire and the second receiving wire, and the test data of the first receiving wire and the second receiving wire are obtained in the receiving device; the direction of the low-resistance body is determined based on the test data obtained by the receiving device, and the positioning detection of the low-resistance body in the area to be detected is realized.

[0008] The solenoid is used to transmit the primary field, which can avoid the grounding loop affecting the accuracy of directional detection, and increases the number of turns of the transmitting coil, thereby increasing the strength of the primary field.

[0009] The first receiving wire and the second receiving wire are orthogonally distributed and are used to receive the secondary field. The planes where the first receiving wire and the second receiving wire are located are perpendicular to each other, and the plane symmetry axes coincide. Not only will the first receiving wire and the second receiving wire not generate mutual inductance, but the primary field magnetic flux of the loop cavity formed by the solenoid in the first receiving wire and the second receiving wire is zero, which cleverly eliminates the interference of the primary field on the detection target, improves the resolution of the detection result, and can achieve the purpose of directional detection.

[0010] The receiving wire assembly is located at the upper or lower part of the solenoid, and there is a height difference between the receiving wire assembly and the solenoid, so that the secondary field magnetic flux passing through the first receiving wire and the second receiving wire can never be zero. At the same time, it is ensured that when a low-resistance body is detected, the first receiving wire and the second receiving wire can always receive the signal of the low-resistance body to ensure a response.

[0011] Optionally, the solenoid adopts a back-wound coil.

[0012] The solenoid adopts a back-winding method, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid, thereby increasing the effective primary field and the excited secondary field, and can avoid the excess interference of the primary field directly led back after the first winding. At the same time, the magnetic field generated by the back-winding coil is consistent with the magnetic field generated by the first winding coil, thereby enhancing the transmitted signal.

[0013] Optionally, the solenoid is a hollow structure, and a magnetic rod is provided at the center of the solenoid.

[0014] The solenoid is a hollow structure, the center of which can be filled with a magnetic rod to further increase the primary field.

[0015] Optionally, central axes of the first receiving wire and the second receiving wire coincide with the central axis of the solenoid.

[0016] The central axes of the first receiving wire and the second receiving wire both coincide with the rotation center of the solenoid, ensuring that the first receiving wire and the second receiving wire are rotationally symmetrical structures. The symmetry of the magnetic field is utilized to ensure that the first receiving wire and the second receiving wire are located on the symmetry plane of the primary field, so that the primary field in all directions does not pass through the first receiving wire and the second receiving wire. The primary field magnetic flux of the loop cavity formed by the solenoid between the first receiving wire and the second receiving wire is zero, which cleverly eliminates the interference of the primary field and improves the detection resolution.

[0017] Optionally, the height of the solenoid is greater than the height of the first receiving wire or the second receiving wire.

[0018] The height of the first receiving wire and the second receiving wire is always less than the length of the solenoid, and the first receiving wire and the second receiving wire are located at the upper part or the lower part of the solenoid, so that the magnetic flux of the secondary field in the first receiving wire and the second receiving wire is always not zero. If the solenoid and the receiving coil are at the same height, when the low-resistance body is located in the middle of the device, the magnetic flux will be symmetrically offset up and down, weakening the received signal.

[0019] Optionally, the height of the solenoid is greater than the height of the first receiving wire or the second receiving wire. The height of the solenoid is greater than or equal to twice the height of the first receiving wire or the second receiving wire.

[0020] Optionally, the receiving device is one of a coil sensor, a magnetic bar sensor, a magnetoresistive sensor and a Hall sensor.

[0021] The present invention also provides a directional detection method of electromagnetic induction, comprising the following steps:

[0022] S1. A solenoid and a receiving wire assembly are arranged in the intended detection area, the solenoid is connected to a transmitting device, the receiving wire assembly is arranged at the upper part or the lower part of the solenoid, the receiving wire assembly comprises a first receiving wire and a second receiving wire which are orthogonally distributed, the first receiving wire and the second receiving wire are both connected to the receiving device, and the primary field magnetic flux of the loop cavity formed by the solenoid, the first receiving wire and the second receiving wire is zero;

[0023] S2, turn on the transmitting device, and the transmitting device supplies current to the solenoid;

[0024] S3, turn off the transmitting device, if the receiving device receives the signal generated by the low-resistance body in the intended detection area through the receiving wire assembly and obtains the test data, it proves that there is a low-resistance body in the intended detection area, otherwise, there is no low-resistance body in the intended detection area;

[0025] S4. Determine the direction of the low-resistance body based on the test data obtained by the receiving device.

[0026] Optionally, in step S3, the receiving device receives the signal generated by the low-resistance body in the intended detection area and obtains the test data by turning off the transmitting device, and the receiving device obtains the induced electromotive force E of the first receiving wire through the first receiving wire and the second receiving wire respectively. x The attenuation curve of the second receiving wire and the induced electromotive force E y The decay curve.

[0027] Optionally, step S4 is specifically: according to the induced electromotive force E of the first receiving wire x The attenuation curve of the second receiving wire and the induced electromotive force E y The attenuation curve of the solenoid is used to obtain the direction of the low-resistance body relative to the central axis of the solenoid.

[0028] Optionally, the direction of the low-resistance body relative to the central axis of the solenoid is obtained according to the angle θ of the low-resistance body relative to the central axis of the solenoid. The angle θ of the low-resistance body relative to the central axis of the solenoid is calculated as follows:

[0029]

[0030] Beneficial effects:

[0031] 1. The present invention sets a transmitting device, a receiving device, a solenoid and a receiving wire assembly. During use, the solenoid is first connected to the transmitting device; secondly, the first receiving wire and the second receiving wire are both connected to the receiving device; then the electromagnetic induction directional detection device is placed in the borehole of the area to be detected, and the power of the transmitting device is turned on; after a period of time, the power is turned off. According to Faraday's law of electromagnetic induction, the low-resistance body in the area to be detected will form eddy currents inside, generating a secondary magnetic field that decays with time and is received by the first receiving wire and the second receiving wire, and the test data of the first receiving wire and the second receiving wire are obtained in the receiving device; the direction of the low-resistance body is determined according to the test data obtained by the receiving device, so as to realize the positioning detection of the low-resistance body in the area to be detected.

[0032] 2. The present invention provides a solenoid for transmitting a primary field, which can avoid the grounding loop affecting the accuracy of directional detection, and increases the number of turns of the transmitting coil, thereby increasing the primary field.

[0033] 3. In the present invention, the receiving wire assembly is located at the upper or lower part of the solenoid, and there is a height difference between the receiving wire assembly and the solenoid, so that the secondary field magnetic flux passing through the first receiving wire and the second receiving wire can never be zero. At the same time, it is ensured that when a low-resistance body is detected, the first receiving wire and the second receiving wire can always receive the signal of the low-resistance body to ensure a response.

[0034] 4. In the present invention, the first receiving wire and the second receiving wire are orthogonally distributed and are used to receive the secondary field. The planes where the first receiving wire and the second receiving wire are located are perpendicular to each other, and the plane symmetry axes coincide. Not only will the first receiving wire and the second receiving wire not generate mutual inductance, but the primary field magnetic flux of the loop cavity formed by the solenoid in the first receiving wire and the second receiving wire is zero, which cleverly eliminates the interference of the primary field on the detection target, improves the resolution of the detection result, and can achieve the purpose of directional detection.

[0035] 5. The solenoid in the present invention adopts a back-winding method, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid, thereby increasing the effective primary field and the excited secondary field, and can avoid the redundant interference primary field generated by directly leading back after the first winding. At the same time, the magnetic field generated by the back-winding coil is consistent with the magnetic field generated by the first winding coil, thereby enhancing the transmitted signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0037] Figure 1 It is a structural diagram of the electromagnetic induction directional detection device disclosed in the present invention;

[0038] Figure 2 It is a top view of the primary field emitted by the solenoid in the electromagnetic induction directional detection device disclosed in the present invention;

[0039] Figure 3 It is a front view of the solenoid emitting a primary field in the electromagnetic induction directional detection device disclosed in the present invention;

[0040] Figure 4 A top view of a low-resistance body measured by the electromagnetic induction directional detection device disclosed in the present invention;

[0041] Figure 5 It is a front view of a low-resistance body measured by the electromagnetic induction directional detection device disclosed in the present invention;

[0042] Figure 6 It is a curve diagram of the attenuation of the induced electromotive force of the receiving wire assembly in the electromagnetic induction directional detection method disclosed in the present invention;

[0043] Figure 7 A comparison diagram of the measured direction and the preset direction of the low-resistance body in the electromagnetic induction directional detection method disclosed in the present invention;

[0044] Figure 8 The present invention discloses a comparison diagram of the measured direction and the preset direction of a low-resistance body in the electromagnetic induction directional detection method when the low-resistance body is in multiple preset directions.

[0045] Reference numerals: 1 transmitting device; 2 solenoid; 3 low-resistance body; 41 first receiving wire; 42 second receiving wire; 5 receiving device.

[0046] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0049] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0050] Embodiment 1:

[0051] See also Figure 1-5 , according to an embodiment of the present invention, an electromagnetic induction directional detection device comprises a transmitting device 1, a receiving device 5, a solenoid 2 and a receiving wire assembly;

[0052] The solenoid 2 is connected to the transmitting device 1, and the receiving wire assembly is located at the upper part or the lower part of the solenoid 2. The receiving wire assembly includes a first receiving wire 41 and a second receiving wire 42 that are orthogonally distributed. The first receiving wire 41 and the second receiving wire 42 are both connected to the receiving device 5. The primary field magnetic flux of the loop cavity formed by the solenoid 2 in the first receiving wire 41 and the second receiving wire 42 is zero.

[0053] Specifically, during use, the solenoid 2 is first connected to the transmitting device 1; secondly, the first receiving wire 41 and the second receiving wire 42 are both connected to the receiving device 5; then the electromagnetic induction directional detection device is placed in the borehole of the area to be detected, and the power of the transmitting device 1 is turned on; after a period of time, the power is turned off. According to Faraday's law of electromagnetic induction, the low-resistance body 3 in the area to be detected will form eddy currents inside, generating a secondary magnetic field that decays with time and is received by the first receiving wire 41 and the second receiving wire 42. The test data of the first receiving wire 41 and the second receiving wire 42 are obtained in the receiving device 5; the direction of the low-resistance body 3 is determined according to the test data obtained by the receiving device 5, so as to realize the positioning detection of the low-resistance body 3 in the area to be detected.

[0054] The solenoid 2 is used to transmit the primary field, which can avoid the grounding loop affecting the accuracy of directional detection, and increase the number of turns of the transmitting coil to increase the primary field.

[0055] The first receiving wire 41 and the second receiving wire 42 are orthogonally distributed and are used to receive the secondary field. The planes where the first receiving wire 41 and the second receiving wire 42 are located are perpendicular to each other, and the plane symmetry axes coincide. Not only will the first receiving wire 41 and the second receiving wire 42 not generate mutual inductance, but the primary field magnetic flux of the loop cavity formed by the solenoid 2 in the first receiving wire 41 and the second receiving wire 42 is zero, which cleverly eliminates the interference of the primary field on the detection target, improves the resolution of the detection result, and can achieve the purpose of directional detection.

[0056] The receiving wire assembly is located at the upper or lower part of the solenoid 2, and there is a height difference between the receiving wire assembly and the solenoid 2, so that the secondary field magnetic flux passing through the first receiving wire 41 and the second receiving wire 42 can never be zero. At the same time, it is ensured that when the low-resistance body 3 is detected, the first receiving wire 41 and the second receiving wire 42 can always receive the signal of the low-resistance body 3 to ensure a response.

[0057] Since a single measurement may have contingency and errors, multiple measurements can be made at the same point in the area to be detected, and measurements can be made at different points in the area to be detected. If the azimuth vectors measured at multiple different points point to the same point, it can be considered that the low-resistance body 3 is located near the point. The solenoid 2 includes two sections of equal length, and the coils of the two sections of the solenoid 2 are in a positive series relationship.

[0058] Compared with the invention with publication number CN116224448A which uses a straight transmitting wire, the present invention uses a solenoid 2, and the intensity of the primary field is significantly increased. In order to simplify the calculation, the low-resistance body in the measured area is equivalent to a ring with a diameter of 10 cm. When the transmitting device is a straight wire, the current is 1A, and the distance from the measured low-resistance body is 20 cm, the Biot-Savart law is used:

[0059]

[0060] Among them, B 1 is the magnetic induction intensity of the primary field; μ 0 is the magnetic permeability in vacuum; I is the magnitude of the current in the wire; L represents the wire; dl represents a directed unit of the wire; R represents the distance from a point in space to dl.

[0061] Combined with the magnetic flux calculation formula:

[0062]

[0063] in, represents the magnetic flux in the ring; S represents the directed area of ​​the ring; ds represents a unit of S. It can be calculated that the magnetic flux of the equivalent ring is about 7.97×10 -9 Wb.

[0064] When the transmitting device is a solenoid with a diameter of 10 cm, it is also powered by 1A, 50 turns, and is 20 cm away from the low-resistance body being measured. Using the above formula, the magnetic flux of the equivalent circular ring can be obtained to be approximately 7.5632×10-8Wb. Compared with a straight wire, the magnetic flux of the solenoid is increased by about 10 times. If the number of turns is further increased, the magnetic flux will be further increased.

[0065] See also Figure 1 In some embodiments of the present invention, the solenoid 2 is a back-wound coil.

[0066] The solenoid 2 adopts a back-winding method, which increases the number of turns of the transmitting coil, increases the primary field, and increases the inductance of the solenoid 2, thereby increasing the effective primary field and the excited secondary field, and can avoid the unnecessary interference of the primary field directly led back after the first winding. At the same time, the magnetic field generated by the back-winding coil is consistent with the magnetic field generated by the first winding coil, thereby enhancing the transmitted signal.

[0067] Assuming that the solenoid 2 is directly led back to connect to the transmitting device after one winding, the led-back line is inconsistent with the magnetic field originally generated by the solenoid 2, and the led-back line passes through the first receiving wire 41 and the second receiving wire 42, which will generate unnecessary primary field interference.

[0068] See also Figure 1 In some embodiments of the present invention, the solenoid 2 is a hollow structure, and a magnetic rod is provided at the center of the solenoid 2.

[0069] The solenoid 2 is a hollow structure, the center of which can be filled with a magnetic rod to further increase the primary field.

[0070] See also Figure 3 and4 In some embodiments of the present invention, the central axes of the first receiving wire 41 and the second receiving wire 42 coincide with the central axis of the solenoid 2 .

[0071] The central axes of the first receiving wire 41 and the second receiving wire 42 coincide with the rotation center of the solenoid 2, ensuring that the first receiving wire 41 and the second receiving wire 42 are rotationally symmetrical structures. The symmetry of the magnetic field is used to ensure that the first receiving wire 41 and the second receiving wire 42 are located on the symmetry plane of the primary field, so that the primary field in all directions does not pass through the first receiving wire 41 and the second receiving wire 42. The primary field magnetic flux of the loop cavity formed by the solenoid 2 with the first receiving wire 41 and the second receiving wire 42 is zero, which cleverly eliminates the interference of the primary field and improves the detection resolution.

[0072] See also Figure 1 In some embodiments of the present invention, the height of the solenoid 2 is greater than the height of the first receiving wire 41 or the second receiving wire 42 .

[0073] The height of the first receiving wire 41 and the second receiving wire 42 is always less than the length of the solenoid 2, and the first receiving wire 41 and the second receiving wire 42 are located at the upper part or the lower part of the solenoid 2, so that the magnetic flux of the secondary field in the first receiving wire 41 and the second receiving wire 42 is always not zero. If the solenoid 2 is the same height as the receiving coil, when the low-resistance body 3 is located in the middle of the device, the magnetic flux will be symmetrically offset up and down, weakening the received signal.

[0074] See also Figure 1 In some embodiments of the present invention, the height of the solenoid 2 is greater than or equal to twice the height of the first receiving wire 41 or the second receiving wire 42 .

[0075] The height of the solenoid 2 is twice that of the receiving coil, that is, there is a certain height difference, and the first receiving wire 41 and the second receiving wire 42 are located at the upper part or the lower part of the solenoid 2, so that the magnetic flux of the secondary field in the first receiving wire 41 and the second receiving wire 42 is always not zero.

[0076] See also Figure 1 In some embodiments of the present invention, the receiving device 5 is one of a coil sensor, a magnetic bar sensor, a magnetoresistive sensor and a Hall sensor.

[0077] Embodiment 2:

[0078] See also Figure 4-8 According to an embodiment of the present invention, a directional detection method of electromagnetic induction includes the following steps:

[0079] S1. A solenoid 2 and a receiving wire assembly are arranged in the intended detection area, the solenoid 2 is connected to the transmitting device 1, the receiving wire assembly is arranged at the upper part or the lower part of the solenoid 2, the receiving wire assembly includes a first receiving wire 41 and a second receiving wire 42 which are orthogonally distributed, the first receiving wire 41 and the second receiving wire 42 are both connected to the receiving device 5, and the primary field magnetic flux of the loop cavity formed by the solenoid 2 at the first receiving wire 41 and the second receiving wire 42 is zero;

[0080] S2, turn on the transmitting device 1, and the transmitting device 1 supplies current to the solenoid 2;

[0081] S3, turn off the transmitting device 1, if the receiving device 5 receives the signal generated by the low-resistance body 3 in the intended detection area through the receiving wire assembly and obtains the test data, it proves that there is a low-resistance body 3 in the intended detection area, otherwise, there is no low-resistance body 3 in the intended detection area;

[0082] S4. Determine the direction of the low-resistance body 3 according to the test data obtained by the receiving device 5.

[0083] See also Figure 5 and 6 In some embodiments of the present invention, in step S3, the receiving device 5 receives the signal generated by the low-resistance body 3 in the intended detection area and obtains the test data as follows: the transmitting device 1 is turned off, and the receiving device 5 obtains the induced electromotive force E of the first receiving wire 41 through the first receiving wire 41 and the second receiving wire 42. x The attenuation curve of the second receiving wire 42 and the induced electromotive force E y The decay curve.

[0084] See also Figure 6 In some embodiments of the present invention, step S4 is specifically: according to the first receiving wire 41 induced electromotive force E x The attenuation curve of the second receiving wire 42 and the induced electromotive force E y The attenuation curve of the low-resistance body 3 is obtained to obtain the direction of the low-resistance body 3 relative to the central axis of the solenoid 2. The direction of the low-resistance body 3 relative to the central axis of the solenoid 2 is obtained according to the angle θ of the low-resistance body 3 relative to the central axis of the solenoid 2. The angle θ of the low-resistance body 3 relative to the central axis of the solenoid 2 is calculated as follows:

[0085]

[0086] In this embodiment, the transmitting device 1 is turned off after being turned on for a period of time, and the current of the solenoid 2 is cut off. Due to the existence of eddy currents in the low-resistance body 3, an attenuated secondary field will be generated and received by the first receiving wire 41 and the second receiving wire 42, and the signal strengths of these two groups of attenuation are proportional to the magnetic flux.

[0087] See also Figure 4 , 5 and 6, Figure 4 and 5 The top view and the front view of the electromagnetic induction directional detection device detecting the low-resistance body 3 are shown. In order to demonstrate the accuracy of the electromagnetic induction directional detection device, the low-resistance body is preset to be located at (-4, -3) of the central axis of the solenoid 2. According to the transient electromagnetic method theory, the following is obtained: Figure 6 The two sets of attenuation curves shown are Figure 6 Medium E x represents the induced electromotive force of the first receiving wire 41 in the x direction, E y The induced electromotive force of the second receiving wire 42 in the y direction is shown.

[0088] See also Figure 7 , using the calculation formula of the angle θ of the low resistance body 3 relative to the central axis of the solenoid 2:

[0089]

[0090] The measured direction of the low-resistance body 3 relative to the central axis of the solenoid 2 can be obtained, and it can be seen that the measured direction of the low-resistance body 3 is substantially consistent with the preset direction.

[0091] See also Figure 8 As shown, the above method is repeated and the electromagnetic induction directional detection device is moved. When the low-resistance body 3 is in each preset direction relative to the central axis of the solenoid 2, the direction of the low-resistance body 3 is measured by the electromagnetic induction directional detection device. The curve represents the comparison between the measured direction of the low-resistance body 3 relative to the central axis of the solenoid 2 and the preset direction. It can be seen that the direction measured by this method is basically consistent with the preset direction, which ensures the accuracy of the electromagnetic induction directional detection device.

[0092] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An electromagnetic induction directional detection device, characterized in that: It includes a transmitting device, a receiving device, a solenoid and a receiving wire assembly; The solenoid is connected to the transmitting device, the receiving wire assembly is located at the upper part or the lower part of the solenoid, the receiving wire assembly includes a first receiving wire and a second receiving wire that are orthogonally distributed, the first receiving wire and the second receiving wire are both connected to the receiving device, and the primary field magnetic flux of the loop cavity formed by the solenoid and the first receiving wire and the second receiving wire is zero.

2. The electromagnetic induction directional detection device according to claim 1, characterized in that: The solenoid uses a back-wound coil.

3. The electromagnetic induction directional detection device according to claim 1, characterized in that: The solenoid is a hollow structure, and a magnetic rod is arranged at the center of the solenoid.

4. The electromagnetic induction directional detection device according to claim 1, characterized in that: The central axes of the first receiving wire and the second receiving wire coincide with the central axis of the solenoid.

5. The electromagnetic induction directional detection device according to any one of claims 1 to 4, characterized in that: The height of the solenoid is greater than the height of the first receiving wire or the second receiving wire.

6. The electromagnetic induction directional detection device according to claim 5, characterized in that: The height of the solenoid is greater than or equal to twice the height of the first receiving wire or the second receiving wire.

7. The electromagnetic induction directional detection device according to any one of claims 1 to 4, characterized in that: The receiving device is one of a coil sensor, a magnetic bar sensor, a magnetoresistive sensor and a Hall sensor.

8. A directional detection method of electromagnetic induction, characterized in that: The steps include: S1. A solenoid and a receiving wire assembly are arranged in the intended detection area, the solenoid is connected to a transmitting device, the receiving wire assembly is arranged at the upper part or the lower part of the solenoid, the receiving wire assembly comprises a first receiving wire and a second receiving wire which are orthogonally distributed, the first receiving wire and the second receiving wire are both connected to the receiving device, and the primary field magnetic flux of the loop cavity formed by the solenoid, the first receiving wire and the second receiving wire is zero; S2, turn on the transmitting device, and the transmitting device supplies current to the solenoid; S3, turn off the transmitting device, if the receiving device receives the signal generated by the low-resistance body in the intended detection area through the receiving wire assembly and obtains the test data, it proves that there is a low-resistance body in the intended detection area, otherwise, there is no low-resistance body in the intended detection area; S4. Determine the direction of the low-resistance body according to the test data obtained by the receiving device.

9. The electromagnetic induction directional detection method according to claim 8, characterized in that: In step S3, the receiving device receives the signal generated by the low-resistance body in the intended detection area and obtains the test data. Specifically, the transmitting device is turned off, and the receiving device obtains the induced electromotive force E of the first receiving wire through the first receiving wire and the second receiving wire. x The attenuation curve of the second receiving wire and the induced electromotive force E y The decay curve.

10. The electromagnetic induction directional detection method according to claim 9, characterized in that: Step S4 is specifically as follows: according to the electromotive force E induced by the first receiving wire x The attenuation curve of the second receiving wire and the induced electromotive force E y The attenuation curve of the low-resistance body is obtained relative to the central axis of the solenoid. The direction of the low-resistance body relative to the central axis of the solenoid is obtained according to the angle θ of the low-resistance body relative to the central axis of the solenoid. The angle θ of the low-resistance body relative to the central axis of the solenoid is calculated as follows:

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