Small electromagnetic ultrasonic sensor and electromagnetic ultrasonic detection equipment

Abstract

The utility model discloses a miniature electromagnetic ultrasonic sensor and electromagnetic ultrasonic detection equipment, the sensor comprises a shell and a sensing assembly, the sensing assembly comprises a magnet and a coil, the magnet comprises a cylindrical magnetic core and an annular magnetic ring surrounding the magnetic core, and the coil is in a concentrically coiled circle shape and is flatly laid below the magnet; in the left side part of the magnetic core, the upper half part is an N pole, the lower half part is an S pole, in the right side part, the upper half part is an S pole, and the lower half part is an N pole; in the left side part of the magnetic ring, the half located on the inner side is an S pole, the half located on the outer side is an N pole, in the right side part, the half located on the inner side is an N pole, and the half located on the outer side is an S pole. The sensor still has enough magnetic field intensity and detection sensitivity under the condition that the size is reduced, and detection operation can still be carried out in a narrow space.

Description

Technical Field

[0001] This utility model relates to the field of electromagnetic ultrasonic sensor technology, specifically to a small electromagnetic ultrasonic sensor and an electromagnetic ultrasonic detection device. Background Technology

[0002] Electromagnetic Acoustic Transducer (EMAT) is a non-contact ultrasonic testing technology that uses electromagnetic principles to excite and receive ultrasonic waves. Compared to traditional contact ultrasonic testing technologies, EMAT does not require a coupling agent, enabling long-distance detection, and is particularly suitable for testing tasks in high-temperature and high-pollution environments. The working principle of EMAT is based on the Lorentz force and eddy current effect. When a conductive material (usually a metal) is placed in an alternating magnetic field, eddy currents are generated within the material. These eddy currents generate a magnetic field opposite to the applied magnetic field, and the interaction of the two magnetic fields forms a Lorentz force. This force causes the material to vibrate, thereby generating ultrasonic waves. EMAT allows for non-contact, non-destructive testing of internal defects in materials, such as cracks and pores. However, traditional electromagnetic ultrasonic sensors are relatively large, making them difficult to operate in confined spaces. Utility Model Content

[0003] The purpose of this invention is to overcome the aforementioned defects or problems in the background art and to provide a small electromagnetic ultrasonic sensor and an electromagnetic ultrasonic detection device that can perform detection operations in a confined space.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] Technical Solution 1: A small electromagnetic ultrasonic sensor, comprising: a housing with its lower end forming a detection end; a sensing assembly installed within the housing and including a magnet and a coil; the magnet comprising a cylindrical magnetic core and a ring-shaped magnetic ring surrounding the magnetic core; the coil being a concentrically coiled circle, laid flat below the magnet; a plane defined as the axis of the magnetic core is a first plane, which divides the magnet into a left side and a right side; in the left side of the magnetic core, the upper half is the N pole and the lower half is the S pole, and in the right side of the magnetic core, the upper half is the S pole and the lower half is the N pole; in the left side of the magnetic ring, the inner half is the S pole and the outer half is the N pole, and in the right side of the magnetic ring, the inner half is the N pole and the outer half is the S pole.

[0006] Technical Solution 2 based on Technical Solution 1: The outer diameter of the coil is the same as the outer diameter of the magnetic core, and it is centered below the magnetic core.

[0007] Technical Solution 3 based on Technical Solution 2: Two layers of coils connected in series are stacked below the magnet.

[0008] Technical solution four based on technical solution three: The lower end of the magnetic ring is flush with the lower end of the magnetic core, and its upper end is higher than the upper end of the magnetic core.

[0009] Technical solution five based on technical solution four: The height difference between the upper end of the magnetic ring and the upper end of the magnetic core is 20% of the length of the magnetic core.

[0010] Technical solution six based on technical solution five: The magnet further includes a copper foil disposed between the magnetic core and the magnetic ring, with the inner and outer sides of the copper foil respectively attached to the outer wall of the magnetic core and the inner wall of the magnetic ring.

[0011] Technical solution seven based on technical solution six: The thickness of the copper foil is 8% of the outer diameter of the magnetic core.

[0012] Technical solution eight based on technical solution seven: the difference between the outer diameter and the inner diameter of the magnetic ring is 22% of the outer diameter of the magnetic core, the length of the magnetic ring is 120% of the length of the magnetic core, and the outer diameter of the magnetic core is not less than 10mm.

[0013] In addition, this utility model also provides technical solution ten: an electromagnetic ultrasonic testing device, which includes a signal generator and a signal processor, and further includes a small electromagnetic ultrasonic sensor as described in any one of technical solutions one to nine, wherein the electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor.

[0014] As can be seen from the above description of this utility model, compared with the prior art, this utility model has the following beneficial effects:

[0015] Technical solution one provides an electromagnetic ultrasonic sensor, which includes a housing and a sensing component. The sensing component is installed inside the housing and includes a magnet and a coil. The magnet includes a magnetic core and a magnetic ring, with the magnetic ring surrounding the magnetic core. The polarity distribution of the magnetic core and the magnetic ring is specially designed. Due to the polarity configuration of the magnetic core and the magnetic ring, the entire magnet forms a composite magnetic field structure. The magnetic core generates a longitudinal magnetic field, and the magnetic ring generates a ring-shaped magnetic field surrounding the magnetic core. The combination of these two elements makes the magnetic field in the sensor's working area more concentrated and uniform, thus allowing the sensor to maintain a high magnetic field strength while reducing its size. Simultaneously, the coil is concentrically wound in a circle and arranged below the magnet. This arrangement matches the magnetic field distribution of the coil and the magnet, maximizing the utilization of the magnetic field generated by the magnet. Furthermore, the coil here also serves as a self-excited and self-receiving element, capable of exciting the vibration of the detected material to generate ultrasonic waves, and receiving ultrasonic waves to generate induction signals. Since the coil is arranged below the magnet and overlaps with the concentrated area of ​​the magnetic field, the coupling loss between the coil and the magnetic field is reduced. Moreover, because the magnetic field is confined to a small area, the coil does not need to be designed to be too large to achieve sufficient induction effect, thereby reducing the space occupied by the coil and the overall size of the sensor. Overall, this sensor, through improvements to the sensing components, including the structural design of the magnet, the configuration of the polarity on the magnet, and the positional relationship between the coil and the magnet, enables the sensor to maintain sufficient magnetic field strength and detection sensitivity while reducing its size, allowing it to perform detection operations in confined spaces.

[0016] In technical solution two, the outer diameter of the coil is the same as the outer diameter of the magnetic core, and it is centered below the magnetic core. This arrangement ensures that the coil is always in the area where the magnetic field is most concentrated, further enhancing the electromagnetic coupling efficiency between the coil and the magnet, reducing magnetic field leakage and ineffective sensing areas, and reducing the non-uniformity of the magnetic field distribution, thus improving signal stability and enabling the sensor to achieve better performance in a smaller size.

[0017] In technical solution three, a double-layer coil is laid out, which can enhance the sensitivity of electromagnetic induction while reducing the size. Furthermore, since the two coils are connected in series and both are located below the magnetic core, the magnetic fields can be superimposed, thereby further enhancing the magnetic field strength of the sensor.

[0018] In technical solution four, the upper end of the magnetic ring is higher than the upper end of the magnetic core. This can suppress the rising signal during the detection process and keep the sound waves generated by the material vibration stable and centered, thereby improving the detection accuracy.

[0019] In technical solution five, the height difference between the upper end of the magnetic ring and the upper end of the magnetic core is limited to 20% of the length of the magnetic core. Under this size limitation, the detection accuracy can be improved.

[0020] In technical solution six, copper foil is also placed between the magnetic core and the magnetic ring to isolate the interference of unwanted magnetic fields on the coil and further improve the detection effect.

[0021] In technical solution seven, the thickness of the copper foil is limited to 8% of the outer diameter of the magnetic core. Under this size limit, the copper foil can be adapted to the size of the magnetic core, thus better isolating unwanted magnetic fields.

[0022] In technical solution eight, the difference between the outer and inner diameters of the magnetic ring is limited, as are the length of the magnetic ring and the length of the magnetic core. Under these size limitations, the fit between the magnetic core and the magnetic ring of the magnet is better, and a high-intensity magnetic field can be provided in a smaller volume, ensuring the detection effect.

[0023] In technical solution nine, a buffer layer made of iron-nickel-cobalt alloy is provided between the coil and the magnetic core, which can improve the stability of the signal and make the magnetic field distribution uniform.

[0024] Technical solution ten provides an electromagnetic ultrasonic testing device, which uses the aforementioned electromagnetic ultrasonic sensor and can perform testing operations in confined spaces. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Schematic diagram of the sensing component in the electromagnetic ultrasonic sensor provided in this embodiment of the utility model Figure 1 ;

[0027] Figure 2 Schematic diagram of the sensing component in the electromagnetic ultrasonic sensor provided in this embodiment of the utility model Figure 2 .

[0028] Explanation of key figure labels:

[0029] Sensing component 1; magnet 2; coil 3; magnetic core 4; magnetic ring 5; first plane 6; left side portion 7; right side portion 8; copper foil 9; buffer layer 10. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are preferred embodiments of the present utility model and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0031] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and drawings of this utility model is for distinguishing different objects and not for describing a specific order.

[0032] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this utility model, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing this utility model and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific protection scope of this utility model.

[0033] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this utility model shall be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or components.

[0034] In the claims, description and accompanying drawings of this utility model, the terms "comprising", "having", and variations thereof are used to mean "including but not limited to".

[0035] Example 1

[0036] Reference Figure 1 and Figure 2This utility model provides an electromagnetic ultrasonic sensor, which can be installed to form an electromagnetic ultrasonic testing device and used to detect surface and internal defects in metallic materials. During the testing process, the electromagnetic ultrasonic sensor can generate mechanical vibration on the material surface by changing the magnetic field or current, thus generating ultrasonic waves. When the ultrasonic waves propagate and reflect in the material, the material will experience slight displacement, thereby changing the magnetic flux distribution of the material and affecting the magnetic field of the coil 3 in the sensor. The sensor can convert the affected signal into a signal and process it to obtain the condition of the surface or internal defects of the material.

[0037] In this embodiment, the electromagnetic ultrasonic sensor includes a housing and a sensing component 1.

[0038] The lower end of the housing forms the detection end. The sensor housing is roughly cylindrical with a small height and overall compact size. During detection, the lower end of the housing forms the detection end, meaning it is close to the material being tested to detect defects. The housing can be made of metal or engineering plastic. Metal housings offer better electromagnetic shielding, while engineering plastics offer better mechanical properties and chemical stability; the choice depends on the specific requirements. Figure 1 and Figure 2 The specific structure of the housing is not shown, but it can be adapted to the shape of the sensing component 1, and will not be described in detail here.

[0039] Reference Figure 1 and Figure 2 ,in Figure 1 The structure of the longitudinal cross-section of the sensing component 1 is shown. Figure 2 The top view of the sensing component 1 is shown. The sensing component 1 is installed in a housing and includes a magnet 2 and a coil 3. The magnet 2 includes a cylindrical magnetic core 4 and a ring-shaped magnetic ring 5 surrounding the magnetic core 4. The coil 3 is a concentrically wound circle and is laid flat below the magnet 2.

[0040] Specifically, magnet 2 is roughly cylindrical with a small height, resulting in a small overall volume. The axis of magnet 2 coincides with the axis of the housing, and the inner diameter of the housing roughly matches the outer diameter of magnet 2, allowing magnet 2 to be better installed inside the housing. During installation, the bottom wall of the internal cavity of the housing can be fitted against the coil 3 located below magnet 2, and then a cover plate can be installed on the top of the housing to fix the sensing component 1 inside the housing.

[0041] Reference Figure 1 and Figure 2A plane containing the axis of the magnetic core 4 is defined as a first plane 6, which divides the magnet 2 into a left portion 7 and a right portion 8. In the left portion 7 of the magnetic core 4, the upper half is the N pole and the lower half is the S pole; in the right portion 8, the upper half is the S pole and the lower half is the N pole. In the left portion 7 of the magnetic ring 5, the inner half is the S pole and the outer half is the N pole; in the right portion 8, the inner half is the N pole and the outer half is the S pole.

[0042] Since both the magnetic core 4 and the magnetic ring 5 are rotary structures, the first plane 6 can be any plane containing the axis of the magnetic core 4. In this embodiment, for ease of explanation, the magnet 2 is divided into a left portion 7 and a right portion 8 by a first plane 6. However, the left portion 7 and right portion 8 in the specification and claims do not imply that the magnet 2 has a left and a right side. In this embodiment, both the magnetic core 4 and the magnetic ring 5 are magnetized using neodymium magnets. Magnetization allows for precise configuration of the magnetic poles in the magnetic core 4 and the magnetic ring 5. It should be noted that the terms "upper half," "lower half," "inner half," and "outer half" all refer to equally dividing the corresponding parts of the magnetic core 4 and the magnetic ring 5 structurally.

[0043] Due to the polarity configuration of the magnetic core 4 and the magnetic ring 5, the entire magnet 2 forms a composite magnetic field structure. The magnetic core 4 generates a longitudinal magnetic field, and the magnetic ring 5 generates a ring-shaped magnetic field surrounding the magnetic core 4. The combination of these two elements makes the magnetic field within the sensor's working area more concentrated and uniform, allowing the sensor to maintain a high magnetic field strength even with a reduced size. Simultaneously, the coil 3 is arranged in a concentrically wound circle below the magnet 2. This arrangement matches the magnetic field distribution of the coil 3 with that of the magnet 2, maximizing the utilization of the magnetic field generated by the magnet 2. Furthermore, the coil 3 also functions as a self-excited and self-receiving element, capable of exciting vibrations in the detected material to generate ultrasonic waves and receiving ultrasonic waves. The coil 3 is positioned below the magnet 2 and overlaps with the concentrated area of ​​the magnetic field, reducing the coupling loss between the coil 3 and the magnetic field. Furthermore, since the magnetic field is confined to a smaller area, the coil 3 does not need to be too large to achieve sufficient sensing effect, thus reducing the space occupied by the coil 3 and the overall size of the sensor. Overall, by improving the sensing component 1, including the structural design of the magnet 2, the polarity configuration of the magnet 2, and the positional relationship between the coil 3 and the magnet 2, this sensor maintains sufficient magnetic field strength and detection sensitivity despite its reduced size, enabling detection operations even in confined spaces.

[0044] Reference Figure 1The outer diameter of coil 3 is the same as that of magnetic core 4, and it is centered below magnetic core 4, so that coil 3 is always in the region where the magnetic field is most concentrated. This further enhances the electromagnetic coupling efficiency between coil 3 and magnet 2, reduces magnetic field leakage and ineffective sensing areas, and reduces the non-uniformity of magnetic field distribution, improving signal stability and enabling the sensor to achieve better performance in a smaller size.

[0045] Preferably, two layers of coils 3 connected in series are stacked beneath the magnet 2. Specifically, when these two layers of coils 3 are wound, a single conductive wire can be first wound concentrically from the inside out into a circle as the first layer. Then, the outermost coil 3 of the first layer is bent downwards at an angle and wound from the outside in into a circle as the second layer. Finally, the end of the conductive wire is led out to the outside of the coil 3. At this point, both the beginning and end of the coil 3 are located on the outside of the coil 3, so as to facilitate connection with the signal generator and signal processor in the electromagnetic ultrasonic testing equipment. Furthermore, by laying two layers of coils 3, the sensitivity of electromagnetic induction can be enhanced while reducing the size. And since the two coils 3 are connected in series and both are below the magnetic core 4, the magnetic fields can be superimposed, thereby further enhancing the magnetic field strength of the sensor.

[0046] Reference Figure 1 The lower end of the magnetic ring 5 is flush with the lower end of the magnetic core 4, while its upper end is higher than the upper end of the magnetic core 4. Preferably, the height difference between the upper end of the magnetic ring 5 and the upper end of the magnetic core 4 can be 20% of the length of the magnetic core 4. Having the upper end of the magnetic ring 5 higher than the upper end of the magnetic core 4 can suppress the rising signal during detection and stabilize the sound waves generated by material vibration during detection, thereby improving detection accuracy.

[0047] Reference Figure 1 and Figure 2 The magnet 2 also includes a copper foil 9 disposed between the magnetic core 4 and the magnetic ring 5. The inner and outer sides of the copper foil 9 are respectively attached to the outer wall of the magnetic core 4 and the inner wall of the magnetic ring 5. The copper foil 9 has a purity of more than 99%, which can isolate unwanted magnetic fields from interfering with the coil 3 and further improve the detection effect.

[0048] Preferably, the thickness of the copper foil 9 is 8% of the outer diameter of the magnetic core 4. Under this size constraint, the copper foil 9 can be adapted to the size of the magnetic core 4, thus better isolating unwanted magnetic fields.

[0049] Furthermore, the difference between the outer diameter and inner diameter of the magnetic ring 5 is 22% of the outer diameter of the magnetic core 4, the length of the magnetic ring 5 is 120% of the length of the magnetic core 4, and the outer diameter of the magnetic core 4 is not less than 10 mm. Specifically, in this embodiment, since the purpose of this invention is to provide a small-sized electromagnetic ultrasonic sensor, the outer diameter of the magnetic core 4 is set to 10 mm. At this time, the outer diameter of the magnetic ring 5 is 16 mm, the inner diameter of the magnetic ring 5 is 11.6 mm, the width of the magnetic ring 5 is 4.4 mm, and the thickness of the copper foil 9 is 8 mm. Simultaneously, the height of the magnetic core 4 is set to 5 mm, so the height of the magnetic ring 5 is 6 mm, and the height difference between their upper ends is 1 mm.

[0050] By limiting the difference between the outer and inner diameters of the magnetic ring 5, and by limiting the length of the magnetic ring 5 and the length of the magnetic core 4, the fit between the magnetic core 4 and the magnetic ring 5 of the magnet 2 is better under these size limitations. This allows for the provision of a high-intensity magnetic field in a smaller volume, ensuring the detection effect.

[0051] At the same time, refer to Figure 1 A buffer layer 10 is also provided between the line weight and the magnetic core 4. The buffer layer 10 is an iron-nickel-cobalt alloy, wherein the nickel content is 49%-51%, the iron content is 32%-33%, and the cobalt content is 16%-17%. Through this buffer layer 10 with specific metal composition, the stability of the sensor's excitation and sensing signals can be improved, and the magnetic field distribution can be made more uniform.

[0052] Example 2

[0053] Embodiment 2 of this utility model provides an electromagnetic ultrasonic testing device, which includes a signal generator, a signal processor, and the electromagnetic ultrasonic sensor provided in Embodiment 1. The electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor. This testing device uses the aforementioned electromagnetic ultrasonic sensor and can perform testing operations in confined spaces.

[0054] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this utility model, but does not constitute a limitation on the scope of protection of this utility model. Modifications, equivalent substitutions, or other improvements to the embodiments of this utility model or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this utility model or the foregoing embodiments, should all be included within the scope of protection of this utility model.

Claims

1. A small electromagnetic ultrasonic sensor, characterized in that, include: The housing, with its lower end used to form the detection end; The sensing component (1) is installed inside the housing and includes a magnet (2) and a coil (3); the magnet (2) includes a cylindrical magnetic core (4) and a ring-shaped magnetic ring (5) surrounding the magnetic core (4); the coil (3) is a concentrically coiled circle and is laid flat below the magnet (2); A plane containing the axis of the magnetic core (4) is defined as a first plane (6), which divides the magnet (2) into a left side part (7) and a right side part (8). In the left side part (7) of the magnetic core (4), the upper half is the N pole and the lower half is the S pole. In the right side part (8), the upper half is the S pole and the lower half is the N pole. In the left side part (7) of the magnetic ring (5), the inner half is the S pole and the outer half is the N pole. In the right side part (8), the inner half is the N pole and the outer half is the S pole.

2. The miniature electromagnetic ultrasonic sensor as described in claim 1, characterized in that, The outer diameter of the coil (3) is the same as the outer diameter of the magnetic core (4), and it is located in the center below the magnetic core (4).

3. A small electromagnetic ultrasonic sensor as described in claim 2, characterized in that, Two layers of coils (3) connected in series are stacked below the magnet (2).

4. A small electromagnetic ultrasonic sensor as described in claim 2, characterized in that, The lower end of the magnetic ring (5) is flush with the lower end of the magnetic core (4), and its upper end is higher than the upper end of the magnetic core (4).

5. A small electromagnetic ultrasonic sensor as described in claim 4, characterized in that, The height difference between the upper end of the magnetic ring (5) and the upper end of the magnetic core (4) is 20% of the length of the magnetic core (4).

6. A small electromagnetic ultrasonic sensor as described in claim 5, characterized in that, The magnet (2) also includes a copper foil (9) disposed between the magnetic core (4) and the magnetic ring (5), with the inner and outer sides of the copper foil (9) respectively attached to the outer wall of the magnetic core (4) and the inner wall of the magnetic ring (5).

7. A small electromagnetic ultrasonic sensor as described in claim 6, characterized in that, The thickness of the copper foil (9) is 8% of the outer diameter of the magnetic core (4).

8. A miniature electromagnetic ultrasonic sensor as described in any one of claims 1-7, characterized in that, The difference between the outer diameter and the inner diameter of the magnetic ring (5) is 22% of the outer diameter of the magnetic core (4), the length of the magnetic ring (5) is 120% of the length of the magnetic core (4), and the outer diameter of the magnetic core (4) is not less than 10 mm.

9. An electromagnetic ultrasonic testing device, comprising a signal generator and a signal processor, characterized in that, It also includes a small electromagnetic ultrasonic sensor as described in any one of claims 1-8, wherein the electromagnetic ultrasonic sensor is electrically connected to the signal generator and the signal processor.

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