A core can structure

Abstract

This utility model relates to a core sheath structure, including a first sheath and a second sheath. The first sheath is formed by a first annular inner wall, a side wall, and an outer wall to create a first annular cavity; the second sheath is formed by a second annular inner wall, a side wall, and an outer wall to create a second annular cavity. A recessed first snap-fit ​​portion is provided on the inner side of the first annular outer wall, and a recessed second snap-fit ​​portion is provided on the outer side of the second annular outer wall. When the two snap-fit ​​portions are engaged, the outer walls of the first and second annular outer walls are aligned, and the ends of the first and second annular inner walls abut against each other. This structure, without changing the overall volume, eliminates the stop structure between the first and second annular inner walls, reduces the inner wall thickness, and increases the size of the first and second annular cavities, providing more installation space for magnetic materials and improving the overload capacity of the transformer. Simultaneously, the first and second snap-fit ​​portions form an outer wall stop structure, achieving precise fit between the two sheaths, improving the fit strength, and effectively solving the problems of easy loosening and opening of the sheaths in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of iron core protective shell technology, and in particular to an iron core protective shell structure. Background Technology

[0002] In the power industry, instrument transformers are key equipment, and their performance and size are crucial to the stable operation of the power system and the efficiency of space utilization. With the continuous development of power technology and the increasing market demand, more stringent requirements are being placed on the performance of instrument transformers, specifically the need for miniaturization of their physical dimensions and increased overload capacity.

[0003] The transformer core, as its core component, directly determines the overall performance of the transformer. However, the magnetic properties of magnetic materials change when subjected to stress, which can adversely affect the performance of the transformer. To ensure reliable performance of the transformer in complex operating environments, the transformer core is usually protected by a casing.

[0004] Existing transformer core housing structures typically consist of two mating housings. To achieve a precise fit between the two housings, both the inner and outer walls of the housings have stop structures. The two housings are fastened together using these stop structures, forming an internal cavity to accommodate the transformer core. However, this structure has significant drawbacks: the manufacturing of the stop structures requires a certain wall thickness, typically at least 0.7 mm, and the presence of stop structures on both the inner and outer walls results in the housing wall thickness occupying a considerable portion of the internal cavity size. This limits the weight of the magnetic material that can be housed internally while maintaining the overall dimensions of the housing, failing to meet market demands for miniaturized transformers with high overload capacity. Utility Model Content

[0005] The purpose of this invention is to optimize the shell design, increase the internal cavity size of the shell while keeping the external dimensions of the shell unchanged, thereby increasing the amount of magnetic material to meet the requirements of miniaturization and high overload capacity of the current transformer.

[0006] To achieve the above objectives, this utility model discloses a core protective shell structure, comprising: a first protective shell, the first protective shell comprising a first annular inner wall, a first annular side wall, and a first annular outer wall connected in sequence, the first annular inner wall, the first annular side wall, and the first annular outer wall forming a first annular cavity; and a second protective shell, the second protective shell comprising a second annular inner wall, a second annular side wall, and a second annular outer wall connected in sequence, the second annular inner wall, the second annular side wall, and the second annular outer wall forming a second annular cavity; wherein, the inner side of the first annular outer wall is provided with a concave first engaging portion, and the outer side of the second annular outer wall is provided with a concave second engaging portion; when the first engaging portion engages with the second engaging portion, the outer side wall of the first annular outer wall is aligned with the outer side wall of the second annular outer wall, and the ends of the first annular inner wall and the second annular inner wall abut against each other.

[0007] By adopting the above scheme, the stop structure between the inner walls of the first and second annular rings is eliminated without changing the overall volume. This reduces the inner wall thickness, directly increasing the size of the first and second annular cavities. This provides more installation space for magnetic materials, allowing for a greater weight of magnetic material to be installed within the same external dimensions, thereby improving the overload capacity of the transformer. Simultaneously, the design of the first and second locking parts forms the stop structure on the outer wall. This not only achieves precise fit between the two sheaths but also significantly improves the fit strength of the sheaths, effectively solving the problems of loosening and opening of the sheaths in existing technologies.

[0008] Furthermore, the first snap-fit ​​portion includes: a first snap-fit ​​edge, the first snap-fit ​​edge being recessed into the inner side of the first annular outer wall; and a first abutting edge, the first abutting edge being connected between the first snap-fit ​​edge and the inner side of the first annular outer wall.

[0009] The second snap-fit ​​portion includes: a second snap-fit ​​edge, which is recessed into the inner side of the second annular outer wall; and a second abutting edge, which is connected between the second snap-fit ​​edge and the inner side of the second annular outer wall; when the first snap-fit ​​portion snaps with the second snap-fit ​​portion, the first snap-fit ​​edge and the second snap-fit ​​edge are in contact, and the first abutting edge and the second abutting edge abut against each other.

[0010] By adopting the above solution, the tight fit and contact relationship allows the two shells to form a stable whole after being snapped together, effectively preventing the shells from moving or separating relative to each other when subjected to external forces, and improving the snapping stability of the shells.

[0011] Furthermore, a first card slot is provided on the first card contact edge, and a second card edge is provided on the second card contact edge, wherein the first card slot and the second card edge are adapted to be engaged.

[0012] By adopting the above scheme, the adapter snap-fit ​​connection creates a deeply interlocking structure between the two housings. Compared to a simple surface contact snap-fit, this structure better resists external pulling and vibration, significantly enhancing the snap-fit ​​strength between the housings and effectively preventing accidental detachment during use. It also restricts the relative horizontal movement of the two housings, further improving the stability of the snap-fit ​​and ensuring reliable fixation of the transformer core within the housing. The tight snap-fit ​​between the first slot and the second ridge reduces gaps between the housings, decreasing the possibility of external environmental factors entering the housing and thus optimizing the housing's sealing performance. Good sealing helps protect the transformer core from external corrosion, extending the transformer's service life.

[0013] Furthermore, the aperture of the first annular inner wall is the same as the aperture of the second annular inner wall, and the aperture of the first annular outer wall is the same as the aperture of the second annular outer wall.

[0014] By adopting the above solution, precise alignment of the two housings can be ensured during assembly. When the two housings are snapped together to form a complete housing structure, a precise positioning reference is provided, allowing them to fit perfectly together, reducing assembly errors caused by dimensional deviations, ensuring the accuracy of the transformer core's installation position inside the housing, and thus improving the transformer's electrical performance.

[0015] Furthermore, the thickness of the first annular inner wall is less than the thickness of the first annular outer wall; the thickness of the second annular inner wall is less than the thickness of the second annular outer wall.

[0016] By adopting the above scheme, the reduction in inner wall thickness directly increases the radial dimension of the internal cavity. Under the trend of miniaturization of current transformers, this design allows for the inclusion of more magnetic material without increasing the outer dimensions of the casing.

[0017] Furthermore, if the width of the second annular outer wall is X1, the width of the second annular inner wall is X2, and the width of the second snap-fit ​​edge is X3, then the following relationship exists: X1 = X2 + X3.

[0018] By adopting the above scheme, the position and size of the outer wall can be accurately determined according to the width of the inner wall and the snap-fit ​​edge, thereby ensuring that the two protective shells can be perfectly aligned and snapped together. This reduces the gap between the protective shells, prevents external substances such as dust and moisture from entering the interior of the protective shells, protects the transformer core and other internal components from damage, and improves the reliability and service life of the transformer.

[0019] Furthermore, if the width of the first annular outer wall is X4, the width of the first annular inner wall is X5, and the width of the first snap-fit ​​edge is X6, then the following relationships exist: X4 = X5 = X2; X6 ≤ X3.

[0020] By adopting the above scheme, the first and second protective casings are unified in key dimensions. Under the same external force, the two casings, due to their identical dimensions, also have essentially the same resistance to deformation. This helps maintain the relative positions and stable operating environment of the internal components of the instrument transformer, reduces the impact of casing deformation on the instrument transformer's performance, and improves the overall reliability and service life of the instrument transformer.

[0021] Furthermore, the edges of the first card slot are chamfered, and the edges of the second card edge are chamfered.

[0022] By adopting the above solution, the chamfer makes the contact surface between the locking edge and the locking slot smoother, reducing stress concentration. The chamfer also guides the second locking edge to smoothly enter the first locking slot. During assembly, the operator does not need to precisely align the locking edge and the locking slot; simply bringing the two protective shells roughly together allows the locking edge to slide more easily into the locking slot under the guidance of the chamfer, greatly reducing the difficulty of assembly and improving assembly efficiency.

[0023] Furthermore, the first slot is an annular groove, and the second ridge is an annular protrusion.

[0024] By adopting the above scheme, the matching method of the annular groove and the annular protrusion provides a natural positioning guide for the snap-fit ​​of the two protective shells. During the assembly process, the operator does not need to deliberately adjust the position and angle of the protective shells; simply align the annular protrusion of the second protective shell with the annular groove of the first protective shell and gently push it in to complete the initial positioning and snap-fit.

[0025] Furthermore, the first card slot is centrally located on the first card contact edge, and the second card edge is centrally located on the second card contact edge.

[0026] By adopting the above solution, the snap-fit ​​process eliminates the need for complex adjustments and positioning, reducing assembly difficulties caused by misalignment of the snap-fit ​​edges and slots. This improves the overall structural stability of the transformer housing, effectively protecting internal components and minimizing the impact of housing loosening or deformation on transformer performance, thus extending the transformer's service life.

[0027] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0028] 1. While maintaining the same outer dimensions of the casing, the stop structure between the inner walls of the first and second annular rings was eliminated, allowing for a reduction in the inner wall thickness. This directly increases the dimensions of the first and second annular cavities, providing more installation space for magnetic materials. For example, more magnetic material can be accommodated within the same volume of casing, thereby improving the magnetic energy storage capacity of the instrument transformer. Because more magnetic material can be installed, the instrument transformer has sufficient magnetic energy to cope with overload conditions, effectively improving its overload capacity. This helps the instrument transformer operate stably in complex and variable power systems, reducing faults and damage caused by overloads.

[0029] 2. The first and second snap-fit ​​parts form a stop structure on the outer wall, which ensures precise fit between the two housings during assembly. The snap-fit ​​method of the first and second snap-fit ​​parts greatly improves the fit strength of the housings, allowing them to fit together perfectly and avoiding problems such as misalignment or excessive gaps caused by assembly errors.

[0030] 3. Eliminating the inner wall stop structure simplifies the shell manufacturing process. The processing equipment no longer needs to perform complex stop machining on the inner wall, reducing processing steps and difficulty. This not only lowers processing costs but also improves processing accuracy and production efficiency. Inspectors can more easily check the dimensions, shape, and fit accuracy of the shell, promptly identifying and resolving quality issues. This helps improve product pass rate and consistency, reducing production and after-sales maintenance costs. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present utility model;

[0033] Figure 2 This is a partial exploded structural diagram of an embodiment of the present invention;

[0034] Figure 3 This is a cross-sectional structural diagram of an embodiment of the present utility model;

[0035] Figure 4 This is an exploded cross-sectional view of an embodiment of the present invention.

[0036] Explanation of main reference numerals in the attached drawings: 1. First protective shell; 11. First annular inner wall; 12. First annular side wall; 13. First annular outer wall; 14. First annular cavity; 2. Second protective shell; 21. Second annular inner wall; 22. Second annular side wall; 23. Second annular outer wall; 24. Second annular cavity; 3. First snap-fit ​​part; 31. First snap-fit ​​edge; 311. First snap-fit ​​groove; 32. First abutment edge; 4. Second snap-fit ​​part; 41. Second snap-fit ​​edge; 411. Second snap-fit ​​ridge; 42. Second abutment edge; 5. Chamfer. Detailed Implementation

[0037] 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 only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0038] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0039] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0040] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0041] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0042] The technical solution of this utility model will be further described below with reference to the embodiments and accompanying drawings.

[0043] Please refer to Embodiment 1 of this utility model. Figures 1 to 4 As shown, a core sheath structure is provided, including a first sheath 1 and a second sheath 2. The first sheath 1 is formed by sequentially connecting a first annular inner wall 11, a first annular side wall 12, and a first annular outer wall 13, which together form a first annular cavity 14. The second sheath 2 is formed by sequentially connecting a second annular inner wall 21, a second annular side wall 22, and a second annular outer wall 23, which together form a second annular cavity 24. The ends of the first annular inner wall 11 and the second annular inner wall 21 directly abut against each other, eliminating the traditional inner wall stop structure. Specifically, the thickness of the first annular inner wall 11 is designed to be 0.5 mm, and the thickness of the second annular inner wall 21 is also 0.5 mm, which is a 28.6% reduction compared to the existing 0.7 mm inner wall thickness. This increases the radial dimension of both the first annular cavity 14 and the second annular cavity 24 by 0.4 mm, reduces the single-side wall thickness by 0.2 mm, and increases the volume of magnetic material that can be accommodated inside by approximately 15% while keeping the total height of the sheath unchanged.

[0044] The inner side of the first annular outer wall 13 is provided with a recessed first locking part 3, and the outer side of the second annular outer wall 23 is provided with a recessed second locking part 4. When the first locking part 3 and the second locking part 4 are engaged, the outer wall of the first annular outer wall 13 is aligned with the outer wall of the second annular outer wall 23, and the ends of the first annular inner wall 11 and the second annular inner wall 21 abut against each other. Without changing the overall volume, the stop structure between the first annular inner wall 11 and the second annular inner wall 21 is eliminated, thereby reducing the inner wall thickness and directly increasing the size of the first annular cavity 14 and the second annular cavity 24. This provides more installation space for magnetic materials, allowing for the installation of more magnetic materials within the same external dimensions, thus improving the overload capacity of the transformer. Simultaneously, the design of the first locking part 3 and the second locking part 4 forms a stop structure on the outer wall, which not only achieves precise fit between the two shells but also greatly improves the fit strength of the shells, effectively solving the problem of easy loosening and opening of the shells in the prior art.

[0045] In this embodiment 1, the first snap-fit ​​portion 3 includes a first snap-fit ​​edge 31 and a first abutting edge 32; the second snap-fit ​​portion 4 includes a second snap-fit ​​edge 41 and abutting edge 42. During assembly, the first snap-fit ​​edge 31 fits against the second snap-fit ​​edge 41, and the first abutting edge 32 abuts against the second abutting edge 42, forming an outer wall stop structure. Further, the first snap-fit ​​edge 31 has an annular first snap-fit ​​groove 311, and the second snap-fit ​​edge 41 has an annular second snap-fit ​​ridge 411. The two are tightly snapped together through an interference fit. After snapping, the outer walls of the first annular outer wall 13 and the second annular outer wall 23 are completely aligned without misalignment or gaps. Through the adaptive snap-fit, the two protective shells form a deeply fitted structure when snapped together. Compared to simple surface contact snap-fit, this structure can better resist external pulling and vibration, greatly enhancing the snap-fit ​​strength between the housings and effectively preventing accidental detachment during use. It also restricts the relative movement of the two housings in the horizontal direction, further improving the stability of the housing snap-fit ​​and ensuring reliable fixation of the transformer core inside the housing. The tight snap-fit ​​between the first slot 311 and the second ridge 411 reduces gaps between the housings, decreasing the possibility of external environment entering the housing, thereby optimizing the housing's sealing performance. Good sealing helps protect the transformer core from external corrosion and extends the transformer's service life. In other embodiments, the edges of the first slot 311 and the second ridge 411 are chamfered (5), making the contact surfaces between the ridge and the slot smoother and reducing stress concentration. The chamfer (5) guides the second ridge 411 to smoothly enter the first slot 311. During assembly, operators do not need to precisely align the positions of the locking edge and the locking slot. They only need to roughly bring the two protective shells close together, and the locking edge can slide into the locking slot more easily under the guidance of the chamfer 5, which greatly reduces the difficulty of assembly and improves assembly efficiency.

[0046] It should be noted that the aperture of the first annular inner wall 11 is the same as that of the second annular inner wall 21, and the aperture of the first annular outer wall 13 is the same as that of the second annular outer wall 23. This ensures precise alignment of the two housings during assembly. When the two housings are snapped together to form a complete housing structure, a precise positioning reference is provided, allowing them to fit perfectly together, reducing assembly errors caused by dimensional deviations, ensuring the accuracy of the transformer core's installation position inside the housing, and thus improving the electrical performance of the transformer. The thickness of the first annular inner wall 11 is less than the thickness of the first annular outer wall 13; the thickness of the second annular inner wall 21 is less than the thickness of the second annular outer wall 23. The reduced inner wall thickness directly increases the radial dimension of the internal cavity. In the trend of transformer miniaturization, this design allows for the inclusion of more magnetic material without increasing the overall size of the housing.

[0047] In some embodiments, the width of the second annular outer wall 23 is X1, the width of the second annular inner wall 21 is X2, and the width of the second snap-fit ​​edge 41 is X3. Then, the following relationship exists: X1 = X2 + X3. Based on the widths of the inner wall and the snap-fit ​​edge, the position and size of the outer wall can be accurately determined, ensuring perfect alignment and snap-fit ​​between the two housings. This reduces the gap between the housings, preventing dust, moisture, and other external substances from entering the housing, protecting the transformer core and other internal components from damage, and improving the reliability and service life of the transformer. In other embodiments, the width of the first annular outer wall 13 is X4, the width of the first annular inner wall 11 is X5, and the width of the first snap-fit ​​edge 31 is X6. Then, the following relationship exists: X4 = X5 = X2; X6 ≤ X3. This ensures that the first housing 1 and the second housing 2 are unified in key dimensions. Under the same external force, because the two housings are the same size, their deformation resistance is also basically the same. This helps maintain the relative positions of the internal components of the instrument transformer and the stability of the operating environment, reduces the impact of casing deformation on the performance of the instrument transformer, and improves the overall reliability and service life of the instrument transformer.

[0048] In this embodiment 1, the first slot 311 is an annular groove, and the second ridge 411 is an annular protrusion. The matching method of the annular groove and the annular protrusion provides a natural positioning guide for the snap-fit ​​of the two protective shells. During the assembly process, the operator does not need to deliberately adjust the position and angle of the protective shells. They only need to align the annular protrusion of the second protective shell 2 with the annular slot of the first protective shell 1 and gently push it in to complete the initial positioning and snap-fit.

[0049] In various embodiments, the first slot 311 is centrally located on the first latching edge 31, and the second latching ridge 411 is centrally located on the second latching edge 41. This eliminates the need for complex adjustments and positioning during the latching process, reducing assembly difficulties caused by misalignment between the latching ridge and the slot. This improves the overall structural stability of the transformer housing, effectively protecting internal components, reducing the impact of housing loosening or deformation on transformer performance, and extending the transformer's service life.

[0050] During assembly, the second locking edge 411 of the second protective shell 2 is aligned with the first locking groove 311 of the first protective shell 1, and the initial fitting is guided by the chamfer 5; axial pressure is applied so that the second locking edge 411 is fully embedded in the first locking groove 311. At this time, the first abutting edge 32 and the second abutting edge 42 are in close contact and abut against each other.

[0051] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0052] 1. While maintaining the same outer dimensions of the casing, the stop structure between the first annular inner wall 11 and the second annular inner wall 21 was eliminated, allowing for a reduction in the inner wall thickness. This directly increases the dimensions of the first annular cavity 14 and the second annular cavity 24, providing more installation space for magnetic materials. For example, more magnetic material can be accommodated within the same volume of casing, thereby improving the magnetic energy storage capacity of the instrument transformer. Because more magnetic material can be installed, the instrument transformer has more sufficient magnetic energy to cope with overload conditions, effectively improving its overload capacity. This helps the instrument transformer operate stably in complex and variable power systems, reducing faults and damage caused by overloads.

[0053] 2. The first snap-fit ​​part 3 and the second snap-fit ​​part 4 form a stop structure on the outer wall. This structure ensures that the two shells fit precisely during assembly. The snap-fit ​​method of the first snap-fit ​​part 3 and the second snap-fit ​​part 4 greatly improves the fit strength of the shells, allowing them to fit together perfectly and avoiding problems such as misalignment or excessive gaps caused by assembly errors.

[0054] 3. Eliminating the inner wall stop structure simplifies the shell manufacturing process. The processing equipment no longer needs to perform complex stop machining on the inner wall, reducing processing steps and difficulty. This not only lowers processing costs but also improves processing accuracy and production efficiency. Inspectors can more easily check the dimensions, shape, and fit accuracy of the shell, promptly identifying and resolving quality issues. This helps improve product pass rate and consistency, reducing production and after-sales maintenance costs.

[0055] The above provides a detailed description of a core sheath structure disclosed in the embodiments of this utility model. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the core sheath structure and its core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A core sheath structure, characterized in that, include: The first protective shell (1) includes a first annular inner wall (11), a first annular side wall (12) and a first annular outer wall (13) connected in sequence, and the first annular inner wall (11), the first annular side wall (12) and the first annular outer wall (13) form a first annular cavity (14). The second protective shell (2) includes a second annular inner wall (21), a second annular side wall (22) and a second annular outer wall (23) connected in sequence, and the second annular inner wall (21), the second annular side wall (22) and the second annular outer wall (23) form a second annular cavity (24); The first annular outer wall (13) has a recessed first snap-fit ​​part (3) on its inner side, and the second annular outer wall (23) has a recessed second snap-fit ​​part (4) on its outer side. When the first snap-fit ​​part (3) and the second snap-fit ​​part (4) snap together, the outer wall of the first annular outer wall (13) is aligned with the outer wall of the second annular outer wall (23), and the ends of the first annular inner wall (11) and the second annular inner wall (21) abut against each other.

2. The iron core sheath structure according to claim 1, characterized in that, The first snap-fit ​​portion (3) includes: The first snap-fit ​​edge (31) is recessed inside the first annular outer wall (13); The first abutting edge (32) is connected between the first snap-fit ​​edge (31) and the inner side of the first annular outer wall (13); The second snap-fit ​​part (4) includes: The second snap-fit ​​edge (41) is recessed into the inner side of the second annular outer wall (23); The second abutting edge (42) is connected between the second snap-fit ​​edge (41) and the inner side of the second annular outer wall (23); When the first snap-fit ​​part (3) snaps into the second snap-fit ​​part (4), the first snap-fit ​​edge (31) and the second snap-fit ​​edge (41) are in contact, and the first abutting edge (32) abuts against the second abutting edge (42).

3. The iron core sheath structure according to claim 2, characterized in that, The first card slot (311) is provided on the first card contact edge (31), and the second card edge (41) is provided on the second card contact edge (411). The first card slot (311) and the second card edge (411) are adapted to be connected.

4. The iron core sheath structure according to claim 1, characterized in that, The aperture of the first annular inner wall (11) is the same as the aperture of the second annular inner wall (21), and the aperture of the first annular outer wall (13) is the same as the aperture of the second annular outer wall (23).

5. The iron core sheath structure according to claim 1, characterized in that, The thickness of the first annular inner wall (11) is less than the thickness of the first annular outer wall (13); the thickness of the second annular inner wall (21) is less than the thickness of the second annular outer wall (23).

6. The iron core sheath structure according to claim 2, characterized in that, The width of the second annular outer wall (23) is X1, the width of the second annular inner wall (21) is X2, and the width of the second snap-fit ​​edge (41) is X3. Then the following relationship exists: X1 = X2 + X3.

7. The iron core sheath structure according to claim 6, characterized in that, The width of the first annular outer wall (13) is X4, the width of the first annular inner wall (11) is X5, and the width of the first snap-fit ​​edge (31) is X6. Then the following relationship exists: X4 = X5 = X2; X6 ≤ X3.

8. The iron core sheath structure according to claim 3, characterized in that, The first card slot (311) has a chamfer (5) on its edge, and the second card edge (411) has a chamfer (5) on its edge.

9. The iron core sheath structure according to claim 3, characterized in that, The first slot (311) is an annular groove, and the second ridge (411) is an annular convex ridge.

10. A core sheath structure according to claim 9, characterized in that, The first card slot (311) is centrally located on the first card contact edge (31), and the second card edge (411) is centrally located on the second card contact edge (41).

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