Safety-free tape transformer structure and assembly method

Abstract

The application discloses a safety regulation adhesive tape transformer structure and an assembling method, and belongs to the technical field of transformers. In order to solve the problems of low production efficiency, inconsistent quality and poor heat dissipation of the transformer relying on manual wrapping of safety regulation adhesive tape in the prior art, the application provides a transformer structure adopting a combined shell. The shell comprises a first shell part and a second shell part which can be assembled with each other. The first shell part is provided with a first magnetic core limiting structure and a lead wiring structure; the second shell part is provided with a second magnetic core limiting structure and a lead fixing structure. When assembling, the coil winding and the magnetic core are placed in the first shell part, and the winding conductor is arranged in the lead wiring structure, and then the second shell part is covered with the first shell part. In this process, the magnetic core limiting structures on the two shell parts cooperate to fix the magnetic core, and the lead fixing structure compresses and fixes the winding conductor. The structure does not need adhesive tape, realizes synchronous mechanical fixation of internal elements, is suitable for automatic assembly, and significantly improves production efficiency and product consistency.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, and more specifically to a transformer structure and its assembly method suitable for automated production. Background Technology

[0002] Transformers are indispensable key components in power electronic equipment. Their basic structure typically includes a magnetic core and coil windings wound on the core frame. In traditional transformer manufacturing processes, in order to meet safety requirements, provide electrical insulation, and fix internal components, it is usually necessary to wrap multiple layers of insulating tape around the assembled magnetic core and coil windings, which are known as "safety tapes".

[0003] like Figure 7 As shown, this traditional tape wrapping method is prevalent. However, this process is highly dependent on manual operation. Workers need to manually fold, wrap, and secure the transformer with tape, which not only leads to low production efficiency and high labor costs, but also makes it difficult to achieve fully automated production, thus limiting capacity expansion.

[0004] Furthermore, the unavoidable nature of manual operation also leads to inconsistencies in product quality. For example, the tightness of tape wrapping and alignment accuracy vary from person to person, potentially causing deviations in the final product's dimensions and even affecting the positional accuracy of pins, resulting in a high defect rate. This inconsistency is a significant drawback for downstream applications requiring precise installation.

[0005] At the same time, the structure, which is completely sealed with tape, also restricts the dissipation of heat generated by the transformer during operation. Heat accumulation can cause the transformer temperature to rise, potentially affecting the stability of its electrical performance and even shortening its service life.

[0006] Therefore, there is an urgent need for a new type of transformer structure that can replace the traditional tape wrapping process, is suitable for automated assembly, and can improve product consistency and heat dissipation performance. Summary of the Invention

[0007] In view of the above-mentioned problems in the prior art, the present invention aims to provide a safety tape-free transformer structure and assembly method. Through ingenious mechanical structure design, it replaces the traditional safety tape, realizes reliable fixation of internal components, and is suitable for automated assembly, thereby solving problems such as low production efficiency, poor product consistency and poor heat dissipation.

[0008] To achieve the above objectives, the present invention provides a safety-free tape transformer structure, including a coil winding, a magnetic core, and a housing for enclosing the coil winding and the magnetic core. The housing is a modular housing, comprising a first housing portion and a second housing portion that can be assembled with each other. A first magnetic core limiting structure is provided on the first housing portion, and a second magnetic core limiting structure is provided on the second housing portion. During assembly of the first and second housing portions, the second magnetic core limiting structure cooperates with the first magnetic core limiting structure to mechanically fix the magnetic core. Simultaneously, a lead wire wiring structure is provided on the first housing portion for wiring the winding conductors led from the coil winding; a lead wire fixing structure is provided on the second housing portion. During assembly of the first and second housing portions, the lead wire fixing structure covers and presses against the winding conductors wired by the lead wire wiring structure to fix the winding conductors. Through this design, a simple assembly action can simultaneously achieve dual fixation of the magnetic core and leads.

[0009] In one embodiment, the first housing part is a base and the second housing part is an upper cover. The two are assembled by fitting the upper and lower covers together, which is simple in structure and easy to automate.

[0010] Furthermore, the first magnetic core limiting structure can specifically be a lower magnetic core baffle disposed on the inner wall of the lower base, while the second magnetic core limiting structure can be an upper magnetic core baffle disposed on the inner side of the upper cover. When the upper cover and the lower base are assembled, the upper and lower magnetic core baffles clamp the magnetic core from different directions, thereby achieving a stable mechanical fixation and preventing the magnetic core from loosening.

[0011] Optionally, the lead wiring structure can be embodied as a lead groove disposed on the outside of one side of the lower base, providing a clear and fixed wiring path for the wound conductor. Correspondingly, the lead fixing structure can be a rear cover plate disposed on one side of the upper cover. During assembly, the rear cover plate can precisely cover and press the wound conductor located in the lead groove, ensuring accurate positioning and a firm connection.

[0012] To improve assembly accuracy, the transformer structure may also include a coil positioning structure. This coil positioning structure interacts with the positioning features on the coil winding frame through a receiving space on the first housing portion, to accurately position the coil winding before assembly, providing a reference for the precise fitting of all subsequent components.

[0013] Preferably, the positioning feature is an L-shaped step, and the accommodating space is a small accommodating space adapted to the L-shaped step. This plug-in fit reliably ensures the accuracy of the coil winding's position and orientation within the housing, preventing rotation or displacement during assembly.

[0014] To more reliably secure the conductor ends, the lead wiring structure may also include conductive pin retaining slots for securing the conductor ends, providing initial positioning of the pins before final clamping and securing.

[0015] To improve heat dissipation performance, a heat dissipation vent may be provided on the top of the second housing to provide a channel for dissipating the heat generated during transformer operation, which helps to improve operational stability and extend service life.

[0016] To enhance the stability of the housing assembly, a step may be provided on the upper edge of the lower base, and an inner angle of the step matching the step is provided on the inner side of the upper cover. The two abut against each other when the cover is closed, which not only serves as a guide but also increases the structural strength after assembly.

[0017] The present invention also provides a method for assembling a transformer. The method includes the following steps: providing a combined housing as described above, comprising a first housing portion and a second housing portion; placing a coil winding and a magnetic core within the first housing portion, wherein a first magnetic core limiting structure provides initial positioning for the magnetic core; arranging the winding conductors led from the coil winding in the lead wiring structure; and finally assembling the second housing portion with the first housing portion. During the assembly process, the second magnetic core limiting structure and the first magnetic core limiting structure work together to achieve final mechanical fixation of the magnetic core; and the lead fixing structure simultaneously covers and presses the winding conductors routed by the lead wiring structure to securely fix them.

[0018] In one specific assembly process, before placing the coil winding and magnetic core into the first housing, the inner protrusion of the magnetic core can be inserted into the hollow structure of the coil winding skeleton to pre-assemble the magnetic core and coil into a single unit. This greatly simplifies the gripping and placement operations of automated equipment.

[0019] Compared with existing technologies, the present invention has the following advantages: First, by employing a combined outer shell composed of a first housing part and a second housing part, and integrating a coordinating structure for fixing the magnetic core and leads, the present invention completely replaces the traditional safety tape wrapping process. This allows the transformer assembly process to be automatically completed by mechanical equipment, greatly improving production efficiency, reducing labor costs, and achieving standardized, high-quality continuous production.

[0020] Secondly, by setting up lead wiring and lead fixing structures, the path and final position of the wound conductor can be precisely controlled and reliably fixed. This design effectively solves the problem of inaccurate pin positions (pin defects) caused by improper manual operation, significantly improving the product yield and the reliability of electrical connections.

[0021] Furthermore, the coil positioning structure on the housing ensures precise positioning of core components during assembly, guaranteeing the success rate and consistency of the overall assembly. Optional heat dissipation vents improve the transformer's heat dissipation performance, contributing to enhanced operational stability and service life. In summary, this invention provides an innovative transformer solution suitable for automated production, combining high efficiency, high quality, and high performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the assembly state of a transformer structure provided in an embodiment of the present invention.

[0023] Figure 2 for Figure 1 The diagram shows an exploded view of the transformer structure.

[0024] Figure 3 for Figure 2 The diagram shows the structure of the lower base.

[0025] Figure 4 To show from the rear perspective Figure 2 The exploded view of the transformer structure shown highlights the lead fixing relationship.

[0026] Figure 5 To show from the front view Figure 2 The exploded view of the transformer structure shown is used to highlight the fixing relationship of the magnetic core.

[0027] Figure 6 This is a schematic flowchart of a transformer assembly method provided in an embodiment of the present invention.

[0028] Figure 7 This is a schematic diagram of a transformer structure in the prior art.

[0029] Explanation of reference numerals in the attached figures: 1-Coil winding, 11-Pin, 12-Wound conductor, 13-L-shaped step, 2-Magnetic core, 3-Lower base, 30-Large accommodating space, 31-Small accommodating space, 32-First lead slot, 33-Second lead slot, 34-Conductive foot fixing slot, 35-Lower magnetic core baffle, 36-Step, 4-Upper cover, 41-Heat dissipation vent, 42-Upper magnetic core baffle, 43-Inner corner of step, 44-Rear cover. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] In existing technologies, such as Figure 7 As shown, traditional transformers typically rely on manual application of safety tape for insulation and fixation. This method has several drawbacks. For example, manual wrapping is inefficient and difficult to automate; the quality of the wrapping is inconsistent, with varying tightness, which may affect the electrical performance and safety of the product; furthermore, complete tape coverage hinders heat dissipation during transformer operation, impacting its performance and lifespan. This invention aims to solve the above-mentioned technical problems by providing a transformer structure and assembly method that eliminates the need for safety tape. This structure, through ingenious mechanical design, achieves reliable fixation of internal components and efficient automated assembly.

[0032] The core concept of this invention lies in replacing traditional safety tape with a modular housing. This modular housing consists of at least two assembleable shell sections, internally integrating a series of cooperating positioning and fixing structures. During assembly, the precise positioning and secure fixing of the transformer's core components—the magnetic core and coil leads—can be simultaneously achieved simply by closing the two shell sections. This design not only fundamentally eliminates the manual tape application process, paving the way for fully automated assembly, but also improves the product's heat dissipation performance and the reliability of electrical connections through optimized structural design.

[0033] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the assembly state of the transformer structure provided in an embodiment of the present invention. Figure 2 This is an exploded structural diagram of the transformer. The present invention provides a safety-compliant tape-free transformer structure, which mainly includes a coil winding 1, a magnetic core 2, and a housing for enclosing the coil winding and magnetic core. Unlike existing technologies, the housing in this invention is a modular housing, consisting of two assembleable components: a first housing part and a second housing part. This modular design forms the basis for achieving tape-free automated assembly.

[0034] In one specific embodiment, the first housing portion is specifically a base 3, and the second housing portion is specifically an upper cover 4. For example... Figure 2As shown, the lower base 3 and the upper cover 4 constitute the main external outline of the transformer. They securely house and fix the internal coil winding 1 and magnetic core 2 by interlocking. This combined housing, consisting of the lower base and the upper cover, can be made of engineering plastics with good insulation and mechanical strength, such as PBT and PET, thus structurally replacing the insulation and protection functions of traditional safety tape.

[0035] To achieve automated and high-precision assembly of internal components, this invention precisely defines the position of the coil winding 1 in the initial assembly stage. Specifically, this invention provides a coil positioning structure. This structure is not a single component, but rather achieves its function through the interaction between positioning features on the coil winding 1's own frame and corresponding receiving spaces on the first housing part (i.e., the lower base 3). This design ensures that the coil winding 1 is immediately positioned in a preset and accurate reference position when placed into the lower base 3, providing a prerequisite for the subsequent assembly and fixation of all components.

[0036] Please refer to the following: Figure 3 and Figure 5 The coil positioning structure described above will be explained in more detail below. In a preferred embodiment, the positioning feature provided on the skeleton of the coil winding 1 is an L-shaped step 13. Correspondingly, a small accommodating space 31 adapted to the shape and size of the L-shaped step 13 is provided on the inner bottom surface of the lower base 3. During assembly, the operator or automated robot only needs to place the coil winding 1 inside the lower base 3 and ensure that the L-shaped step 13 falls exactly into the small accommodating space 31. This unique matching in shape not only plays a precise positioning role but also has a foolproof function, avoiding the possibility of the coil winding 1 being placed in the wrong direction or position, thereby significantly improving the success rate of automated assembly and product consistency.

[0037] After accurately positioning coil winding 1, the next step is to install magnetic core 2. Please refer to [link / reference needed]. Figure 2 In this embodiment, the magnetic core 2 is typically formed by joining two E-type or similar magnetic core halves, with an inner protruding post forming its central portion. Correspondingly, the coil winding 1 has a hollow structure in the middle of its frame. During assembly, the inner protruding post of the magnetic core 2 can be inserted into the hollow structure of the coil winding 1 to form a pre-assembled magnetic core-coil assembly. Subsequently, this assembly is placed entirely into the lower base 3. The lower base 3 has a large accommodating space 30 that roughly matches the outer contour of the magnetic core-coil assembly for initial housing of the assembly.

[0038] One of the key innovations of this invention lies in achieving reliable mechanical fixation of the magnetic core 2 through the synergistic effect of the combined housing. To this end, a first magnetic core limiting structure and a second magnetic core limiting structure are respectively provided in the first housing part and the second housing part. These two structures work together at the moment the housing is assembled and closed to form a firm clamping effect on the magnetic core 2, thus eliminating the need for any glue or tape.

[0039] Specifically, please refer to Figure 3 and Figure 5 The first magnetic core limiting structure is a lower magnetic core baffle 35 provided on the inner wall of the lower base 3. When the magnetic core-coil assembly is placed into the lower base 3, the lower outer surface of the magnetic core 2 will abut against the lower magnetic core baffle 35. The lower magnetic core baffle 35 provides a stable bottom and lateral support for the magnetic core 2, preventing it from shaking or shifting in subsequent processes, and plays a role in initial positioning and limiting.

[0040] Cooperating with the lower magnetic core baffle 35 is a second magnetic core limiting structure disposed on the second housing part (i.e., the upper cover 4). Please refer to... Figure 5 In a preferred embodiment, the second magnetic core limiting structure is an upper magnetic core baffle 42 disposed on the inner front end of the upper cover 4. When the upper cover 4 is closed onto the lower base 3, the upper magnetic core baffle 42 will move precisely above the magnetic core 2 and abut against the upper outer surface of the magnetic core 2.

[0041] With the above design, when the lower base 3 and the upper cover 4 are fully assembled, the lower magnetic core baffle 35 supports the magnetic core 2 from below and the side, while the upper magnetic core baffle 42 presses the magnetic core 2 from above. The two baffles form a pair of clamping forces, firmly holding and locking the magnetic core 2 in a predetermined position inside the housing. This purely mechanical cooperative fixing method not only provides reliable and consistent fixing, but also completely replaces the fixing function of traditional tape, which is the core of realizing the tape-free design of this invention.

[0042] Another key innovation of this invention lies in the orderly management and reliable fixation of the winding conductor 12 led out from the coil winding 1. This is also achieved through a cooperative structure on the first housing part and the second housing part. Specifically, the first housing part is provided with a lead wiring structure, while the second housing part is provided with a lead fixing structure.

[0043] Please see Figure 3 and Figure 4The lead wiring structure is described below. This lead wiring structure is located on the outer side of one side of the lower base 3, and its function is to provide a pre-defined, orderly wiring path for the flexible wound conductor 12. In one specific embodiment, the lead wiring structure includes a first lead groove 32 and a second lead groove 33. These lead grooves are recesses formed on the outer wall of the lower base 3, and the wound conductor 12 can be sequentially arranged in these grooves, thereby avoiding problems such as messy, tangled, or short-circuited leads.

[0044] To initially secure the end of the wound conductor 12, the lead wiring structure may further include a conductive foot fixing slot 34. For example... Figure 3 As shown, after the wire conductor 12 is routed along the first lead groove 32 or the second lead groove 33, its end is typically attached to pins 11, which eventually protrude from the housing. The conductive pin retaining slot 34 can engage these pins or conductor ends, providing initial positioning and retaining force to prevent them from springing back or shifting before the upper cover 4 is closed.

[0045] After the initial wiring and positioning of the leads are completed, the final fixing step is accomplished by the lead fixing structure on the upper cover 4. Please refer to [link / reference]. Figure 4 In a preferred embodiment, the lead wire fixing structure is a rear cover plate 44 disposed on one side of the upper cover 4. The rear cover plate 44 is an extension of the upper cover 4, and its position and shape are carefully designed so that it can precisely cover the lead wire wiring structure (i.e., lead wire groove and slot) on the lower base 3 during assembly.

[0046] When the upper cover 4 and the lower base 3 are assembled and closed, the rear cover plate 44 will adhere to and press firmly against the wound conductor 12 located in the first lead groove 32, the second lead groove 33, and the conductive pin fixing slot 34. This "groove + cover" combination firmly presses the originally soft and easily movable wound conductor onto its predetermined path, achieving final and reliable mechanical fixation. This design greatly ensures the positional accuracy and connection firmness of the lead pin 11, thereby significantly reducing the PIN failure rate caused by pin misalignment or poor soldering.

[0047] In summary, the modular housing of this invention, through its internal synergistic structure, simultaneously secures the magnetic core 2 and the winding conductor 12 in a simple "closing" action, demonstrating a highly integrated design ingenuity. To further improve assembly precision and overall structural stability, this invention also provides some preferred structural designs.

[0048] Please see Figure 3In a preferred embodiment, the upper edge of the lower base 3 is provided with a step 36. Correspondingly, an inner angle 43 matching the step 36 is provided on the inner side of the upper cover 4. When the upper cover 4 is closed, the inner surface of the inner angle 43 abuts against the outer surface of the step 36. This stepped interlocking structure can guide and self-align during assembly, ensuring precise alignment of the upper and lower shells, while enhancing the overall structural connection strength and torsional resistance after assembly.

[0049] Furthermore, this invention also provides an improved solution to the problem of poor heat dissipation caused by tape wrapping in existing technologies. Please refer to [link / reference]. Figure 1 and Figure 2 In a preferred embodiment, the top of the upper cover 4 may be provided with heat dissipation vents 41. These vents may be in the form of a grid, strip, or round hole, providing a direct convection and radiation channel for the heat generated inside the transformer due to eddy current and hysteresis losses. Through this design, heat can be effectively dissipated into the surrounding environment, thereby reducing the operating temperature of the transformer. This not only allows the product to perform better in terms of electrical performance but also effectively extends its service life.

[0050] Based on the above-described series of ingenious structural designs, this invention also provides a corresponding transformer assembly method suitable for automated production. Please refer to... Figure 6 The flowchart shown illustrates that the core of this method lies in utilizing the cooperative fixing characteristics of the modular shell, which simplifies the assembly process.

[0051] The assembly method first requires providing a modular housing as described above, which includes a first housing part (such as the base 3 below) and a second housing part (such as the upper cover 4) that can be assembled with each other. The first housing part is pre-equipped with a first magnetic core limiting structure (such as the magnetic core baffle 35 below) and a lead wire wiring structure (such as lead wire grooves 32 and 33), while the second housing part is pre-equipped with a second magnetic core limiting structure (such as the upper magnetic core baffle 42) and a lead wire fixing structure (such as the rear cover 44).

[0052] In an optional pre-processing step, the magnetic core 2 and the coil winding 1 can be pre-assembled. Specifically, the inner protrusion of the magnetic core 2 is inserted into the hollow structure of the coil winding 1 frame to form a magnetic core-coil assembly. This step simplifies subsequent pick-and-place operations and is particularly suitable for robotic arm operations.

[0053] Next, the pre-assembled core-coil assembly (or the coil winding 1 and core 2 respectively) is placed inside the first housing (lower base 3). During this process, the coil positioning structure (such as the L-shaped step 13 and the small accommodating space 31) ensures the precise positioning of the coil winding 1, while the first core limiting structure (lower core baffle 35) provides initial positioning and support for the core 2.

[0054] Subsequently, the winding conductor 12 led out from the coil winding 1 is arranged in the lead wiring structure on the first housing part (lower base 3) according to a preset path. For example, the wire is sequentially embedded into the first lead groove 32 and the second lead groove 33, and the pin connected to its end is snapped into the conductive foot fixing slot 34.

[0055] Finally, the crucial assembly step is performed: assembling the second housing part (upper cover 4) with the first housing part (lower base 3). In this single, continuous closing action, the cooperative fixing mechanism of the present invention is simultaneously triggered. On one hand, the second magnetic core limiting structure (upper magnetic core baffle 42) moves downward and cooperates with the first magnetic core limiting structure (lower magnetic core baffle 35), firmly clamping and fixing the magnetic core 2 from both upper and lower directions. On the other hand, the lead wire fixing structure (rear cover 44) also simultaneously covers and presses against the winding conductor 12 with the wires laid out by the lead wire wiring structure, completing the final fixing of the lead wire.

[0056] This method simplifies the complex process, which originally required multiple independent steps (placing and securing the magnetic core, wire arrangement, securing the leads, and wrapping with tape), into a few simple and easily automated steps. The entire process requires no tape or adhesive, significantly improving production efficiency, reducing labor costs, and ensuring consistently high assembly quality and reliable performance for every product.

Claims

1. A safety-free tape transformer structure, comprising a coil winding (1), a magnetic core (2), and a housing for covering the coil winding and the magnetic core, characterized in that, The outer shell is a modular outer shell, comprising a first shell part and a second shell part that can be assembled with each other; A first magnetic core limiting structure is provided on the first housing portion; The second housing portion is provided with a second magnetic core limiting structure. When the first housing portion and the second housing portion are assembled, the second magnetic core limiting structure cooperates with the first magnetic core limiting structure to mechanically fix the magnetic core. The first housing portion is provided with a lead wire wiring structure for wiring the winding conductors led out from the coil winding; The second housing portion is provided with a lead wire fixing structure. When the first housing portion and the second housing portion are assembled, the lead wire fixing structure covers and presses the wound conductor after it has been wired by the lead wire wiring structure, so as to fix the wound conductor.

2. The transformer structure according to claim 1, characterized in that, The first housing part is a lower base (3), and the second housing part is an upper cover (4). The upper edge of the lower base (3) is provided with a step (36), and the inner side of the upper cover (4) is provided with an inner angle (43) that matches the step.

3. The transformer structure according to claim 2, characterized in that, The first magnetic core limiting structure is a lower magnetic core baffle (35) set on the inner wall of the lower base (3), and the second magnetic core limiting structure is an upper magnetic core baffle (42) set on the inner side of the upper cover (4).

4. The transformer structure according to claim 2, characterized in that, The lead wire wiring structure is a lead wire groove (32, 33) located on the outside of one side of the lower base (3), and the lead wire fixing structure is a rear cover plate (44) located on one side of the upper cover (4).

5. The transformer structure according to claim 1, characterized in that, It also includes a coil positioning structure, which uses the receiving space (31) on the first housing part to cooperate with the positioning feature (13) on the coil winding (1) skeleton to position the coil winding before assembly.

6. The transformer structure according to claim 5, characterized in that, The positioning feature is an L-shaped step (13), and the accommodating space is a small accommodating space (31) adapted to the L-shaped step.

7. The transformer structure according to claim 4, characterized in that, The lead wiring structure also includes a conductive foot fixing slot (34) for fixing the end of the conductor.

8. The transformer structure according to claim 1, characterized in that, The top of the second housing is provided with a heat dissipation vent (41).

9. A method for assembling a transformer, characterized in that, Includes the following steps: A modular housing is provided, the modular housing comprising a first housing part and a second housing part that can be assembled with each other, wherein the first housing part is provided with a first magnetic core limiting structure and a lead wiring structure, and the second housing part is provided with a second magnetic core limiting structure and a lead fixing structure. The coil winding (1) and the magnetic core (2) are placed inside the first housing part, wherein the first magnetic core limiting structure positions the magnetic core; The winding conductors drawn from the coil winding are arranged in the lead wiring structure; The second housing portion is assembled with the first housing portion. During the assembly process: The second magnetic core limiting structure cooperates with the first magnetic core limiting structure to mechanically fix the magnetic core; and... The lead fixing structure covers and presses the wound conductor after it has been wired by the lead wiring structure to fix the wound conductor.

10. The method according to claim 9, characterized in that, Before placing the coil winding and the magnetic core into the first housing portion, the method further includes inserting the inner protrusion of the magnetic core (2) into the hollow structure of the coil winding (1) skeleton to pre-assemble the magnetic core and the coil.

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