High-precision and easy-to-assemble silicon steel transformer

Abstract

This application relates to the technical field of transformers and discloses a high-precision, easily assembled silicon steel transformer, which includes an iron core made of stacked silicon steel sheets and a coil sleeved on the iron core core column. A guiding assembly and a buffer assembly are provided between the iron core and the coil. The guiding assembly is disposed on the surface of the iron core core column to provide physical guidance and limit radial displacement during coil assembly. The buffer assembly is disposed on the lower yoke of the iron core away from the coil to provide cushioning and precise positioning when the coil falls to its final position. This application guides and buffers the coil assembly process through the guiding assembly and buffer assembly, reducing the possibility of coil insulation damage and improving transformer assembly efficiency and long-term operational stability.

Description

Technical Field

[0001] This application relates to the technical field of transformers, and in particular to a high-precision, easily assembled silicon steel transformer. Background Technology

[0002] Silicon steel transformers, as indispensable core power conversion equipment in modern power systems, operate based on the law of electromagnetic induction to achieve precise alternating current voltage increases and decreases. The core of these transformers is constructed from stacked silicon steel sheets with high magnetic permeability and low loss characteristics. This material selection effectively suppresses eddy currents and hysteresis effects, significantly improving the transformer's operating efficiency. Therefore, silicon steel transformers play a crucial role in long-distance, high-capacity power transmission networks and various industrial and civil applications requiring efficient power distribution. Their performance directly affects the energy consumption level, power supply quality, and operational stability of the entire power grid; thus, continuous improvement of their design and manufacturing processes has always been a key focus of technological development in this field.

[0003] In related technologies, silicon steel transformers mainly consist of a core for the magnetic circuit system, coils for the electrical circuit system, and necessary mechanical fixing components. The core typically includes an upper yoke, a lower yoke, and several core posts connecting them, forming a complete closed magnetic circuit. The coils are wound according to a design and must be fitted onto the core posts. During assembly, the conventional procedure is to first remove the upper yoke from the core posts to create space for the coils. After the coils are fitted into each core post, the upper yoke is reset, and a large clamping force is applied to both ends of the core using metal clamps and high-strength bolts. The main purpose of this clamping structure is twofold: first, to ensure the tightness of the stacked core coils, reducing vibration and noise; and second, to effectively limit the axial movement of the coils, preventing loosening or deformation due to the impact of large electromagnetic forces during subsequent operation, thus ensuring the stability of electrical parameters.

[0004] However, the aforementioned silicon steel transformers relying on traditional structures and assembly processes have significant technical drawbacks in actual production. The core problem lies in the fact that, in pursuit of high electromagnetic efficiency, the physical gap between the core column and the inner wall of the coil is designed to be extremely small, posing a significant challenge to assembly. Currently, the coil assembly process heavily relies on the operator's visual observation and personal experience for alignment adjustments. In this situation, the heavy coil is highly susceptible to slight radial misalignment with the core column during lowering, causing the coil's fragile insulation layers (such as insulating paper and insulating rings) to scrape or even collide with the sharp edges of the silicon steel sheets in the core. This damage is not only irreversible but also directly creates safety hazards such as partial discharge or short circuits. More seriously, when dealing with jamming or adjusting the position, the precisely stacked silicon steel sheets may also be misaligned or deformed due to improper mechanical stress, leading to localized deterioration of the core's magnetic properties, increased no-load losses, and ultimately affecting the overall performance and long-term operational reliability of the transformer. Therefore, providing an innovative structure that can fundamentally avoid such assembly damage has become a pressing technical challenge in this field. Summary of the Invention

[0005] To improve the portability and accuracy of assembling silicon steel transformers, this application provides a high-precision, easy-to-assemble silicon steel transformer.

[0006] This application provides a high-precision, easily assembled silicon steel transformer using the following technical solution: A high-precision, easily assembled silicon steel transformer includes an iron core made of stacked silicon steel sheets and a coil sleeved on the iron core core column. The iron core and the coil are provided with a guide assembly and a buffer assembly. The guide assembly is disposed on the surface of the iron core core column to provide physical guidance and limit radial displacement during the coil assembly process. The buffer assembly is disposed on the lower yoke of the iron core on the side away from the coil to provide buffering and precise positioning when the coil falls to its final position.

[0007] By adopting the above technical solution, during coil assembly, the guiding component can radially limit the movement of the coil and core post, ensuring the accuracy of the assembly path and effectively avoiding scratches on the coil insulation layer and damage to the silicon steel sheet caused by human error or misalignment. Simultaneously, the buffer component reduces the impact when the coil falls, ensuring the mechanical structural stability of the coil and core, while also guaranteeing the insulation performance of the coil and core. Therefore, while improving assembly efficiency and quality consistency, this significantly enhances the transformer's factory reliability and long-term operational stability.

[0008] Optionally, the guiding assembly includes an insulating ring disposed on the iron core column and a plurality of guide strips disposed on the side of the insulating ring near the coil. The insulating ring extends axially along the iron core column, and the guide strips are fixedly connected to the insulating ring. The sidewall of the guide strip away from the iron core column is a smooth arc-shaped guiding surface, and a guide groove adapted to the guide strip is formed on the insulating cardboard inside the coil.

[0009] By adopting the above technical solution, firstly, using the insulating ring as the installation base eliminates the need to alter the core magnetic circuit structure of the iron core, avoiding potential magnetic flux distortion and increased local losses caused by the guide strip, thus ensuring the product's electrical performance. Secondly, the guide strip and the guide groove on the coil insulation paperboard form a precise tenon-and-mortise fit, transforming the traditional suspended centering into sliding along the track, greatly reducing assembly difficulty and reliance on operator skills, achieving foolproof precise guidance, and fundamentally reducing radial deviation.

[0010] Optionally, the cross-section of the guide strip is semi-circular, and the radius of the guide strip gradually increases from the top to the bottom of the iron core column.

[0011] By adopting the above technical solution, during coil installation, the guide bar's tapered design, with its radius gradually increasing from top to bottom, allows for easy guidance even with minor alignment errors during the initial coil lowering stage, thanks to the smaller radius at the top. As the coil continues to fall, the guide bar's radius increases, gradually reducing the gap between it and the guide groove. This progressively corrects and improves alignment accuracy, ultimately achieving a perfect concentric fit. This two-stage guiding mechanism, which first guides and then precisely positions, further enhances the assembly's fault tolerance and success rate, ensuring a smooth and seamless assembly process.

[0012] Optionally, the guide bar is provided with a permanent magnet, and the groove wall of the guide groove is provided with a layer of magnetic material.

[0013] By adopting the above technical solution, a magnetic-assisted centering mechanism is introduced. Utilizing the radial magnetic attraction generated between the permanent magnet and the magnetically conductive material layer, the coil exhibits a tendency to self-center during assembly. This magnetic force can automatically and passively correct minute centering deviations, guiding the coil's guide slot to actively "find" and conform to the guide strip, achieving dynamic and precise positioning. This not only further reduces the risk of jamming but also makes the entire descent process smoother and more stable, minimizing human intervention and achieving a higher degree of automated assembly.

[0014] Optionally, the buffer assembly includes a base disposed on the side of the lower yoke of the iron core away from the coil, an elastic buffer post disposed on the base, a support platform disposed on the top of the elastic buffer post, and a positioning pin disposed on the support platform. The support platform is used to support the bottom of the coil, and a positioning hole corresponding to the positioning pin is opened on the insulating end plate at the bottom of the coil. The positioning pin extends into the positioning hole to realize the circumferential positioning of the coil.

[0015] By adopting the above technical solution, during the coil's descent, the insulating end plate on the coil first contacts the supporting platform, causing the positioning pin to extend into the positioning hole, thereby hindering coil rotation and ensuring the coil's stability during subsequent clamping installation. Then, the coil pushes the supporting platform towards the base, causing the elastic buffer column to undergo elastic deformation, thus absorbing and dissipating the enormous kinetic energy of the coil's descent. This transforms the coil's hard impact into a flexible buffer, reducing damage to the coil, insulating end plate, and lower yoke of the core caused by the impact. Simultaneously, the cooperation between the positioning pin and the positioning hole automatically achieves precise circumferential locking of the coil after the buffering process, preventing rotation during subsequent clamping or operation. This ensures a balanced ampere-turn distribution in each phase coil, laying a solid foundation for the transformer to achieve excellent electrical performance and short-circuit withstand capability, realizing a soft landing during coil descent and precise final positioning.

[0016] Optionally, the elastic buffer column includes an outer sleeve disposed on the base, an inner sliding column slidably disposed in the outer sleeve, and a buffer spring disposed in the outer sleeve. One end of the buffer spring is connected to the inner sliding column, and the other end of the inner sliding column is connected to the support platform.

[0017] By adopting the above technical solution, when the coil falls, it pushes the supporting platform towards the base, thereby pushing the inner sliding column towards the base and compressing the buffer spring. This buffer spring mechanical structure provides stable, reliable, and age-free cushioning force. Through the cooperation of the inner sliding column and the buffer spring, this structure converts the impact kinetic energy into the spring's potential energy, making the cushioning process linear and controllable. Compared to purely elastic body cushioning, this structure has a longer lifespan, and its performance does not change significantly with temperature and time, ensuring consistent and reliable cushioning performance during long-term use and repeated maintenance and assembly.

[0018] Optionally, the inner sliding column is provided with a connecting rod at one end near the outer sleeve, and a piston disc is provided on the connecting rod. The connecting rod is slidably disposed on the inner sliding column, the buffer spring is sleeved on the connecting rod, the piston disc is slidably disposed on the inner wall of the outer sleeve, and a receiving cavity is formed in the outer sleeve on the side of the piston disc away from the connecting rod. The receiving cavity is injected with buffer solution, and a pressure relief hole is provided on the piston disc.

[0019] By adopting the above technical solution, when the coil falls rapidly, the inner sliding column first compresses the buffer spring, and then continues to push the piston disc to squeeze the buffer solution. The liquid is forced to pass through the pressure relief hole to generate a throttling effect, forming a damping force proportional to the movement speed. This damping force can quickly suppress the rebound oscillation generated when the spring is compressed, so that the coil can smoothly and without impact reach the destination in one go, reducing the possibility of the coil repeatedly bouncing on the support platform, greatly improving the stability and efficiency of the buffer, and further protecting the coil.

[0020] Optionally, an installation groove is provided on the inner wall of the outer sleeve, and a locking block is slidably disposed in the installation groove in the horizontal direction. A locking spring is provided on the side of the locking block away from the inner sliding column. The locking spring has a tendency to drive the locking block out of the installation groove. A locking groove is provided on the inner sliding column. When the coil is installed in place, the locking block extends into the locking groove. An unlocking rod is provided on the locking block. An unlocking hole communicating with the installation groove is provided on the outer wall of the outer sleeve, and the unlocking rod extends out of the outer sleeve along the unlocking hole.

[0021] By adopting the above technical solution, the locking block automatically extends into the locking groove after buffering, achieving mechanical locking of the coil's axial position. When the coil compresses the inner sliding column to the working position, the locking block, under the action of the spring, engages in the locking groove, forming a rigid support. This prevents the elastic buffer column from being accidentally compressed or rebounding during transformer transportation, installation, or when subjected to short-circuit electrodynamic forces, ensuring the structural stability of the coil under dynamic operating conditions. When the coil needs maintenance, it can be removed from the core column for maintenance or replacement. Then, the unlocking rod is moved away from the inner sliding column, causing the locking block to move out of the locking groove. The inner sliding column then moves away from the base under the action of the buffer spring, allowing the buffer spring to return to its initial uncompressed state. The buffer solution flows back into the receiving cavity along the pressure relief hole, facilitating buffering of the coil during the next coil installation. The unlocking rod allows for manual unlocking of the locking block during subsequent maintenance, enabling the elastic buffer column to be reused for repeated coil buffering during subsequent coil maintenance.

[0022] In summary, this application includes at least one of the following beneficial technical effects: With the built-in guiding and buffering mechanism, the guide bar slides in the guide groove when the coil is installed, which effectively avoids the scratching and collision damage between the coil insulation layer and the iron core silicon steel sheet during the assembly process. This eliminates the hidden dangers of partial discharge and short circuit caused by assembly damage from the source, reduces the dependence on workers' experience, and significantly improves assembly accuracy and efficiency. The coil achieves a soft landing through a buffer system consisting of a buffer spring and a buffer solution, and achieves precise circumferential positioning through a positioning pin and a positioning hole. This protects the coil from impact damage and ensures the accuracy of the coil's final position. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0024] Figure 2 This is a cross-sectional structural diagram of an embodiment of this application.

[0025] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0026] Figure 4 This is a partial cross-sectional structural diagram of the locking block used in an embodiment of this application.

[0027] Figure 5 This is a partial cross-sectional structural diagram used to illustrate the unlocking hole in an embodiment of this application.

[0028] Explanation of reference numerals in the attached figures: 1. Iron core; 2. Coil; 3. Guide assembly; 31. Insulating ring; 32. Guide bar; 321. Permanent magnet; 33. Guide groove; 331. Magnetic material layer; 4. Buffer assembly; 41. Base; 42. Elastic buffer column; 421. Outer sleeve; 422. Inner sliding column; 423. Buffer spring; 424. Connecting rod; 425. Piston disc; 426. Receiving cavity; 427. Pressure relief hole; 428. Mounting groove; 429. Locking block; 43. Supporting platform; 44. Positioning pin; 5. Locking spring; 6. Locking groove; 7. Unlocking rod; 8. Unlocking hole; 9. Positioning hole. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0030] This application discloses a high-precision, easily assembled silicon steel transformer.

[0031] Reference Figure 1 and Figure 2 A high-precision, easily assembled silicon steel transformer includes an iron core 1, a coil 2, a guide assembly 3, and a buffer assembly 4. The iron core 1 is made of stacked silicon steel sheets, the coil 2 is sleeved on the core post of the iron core 1, the guide assembly 3 is disposed on the surface of the core post of the iron core 1, and the buffer assembly 4 is disposed on the side of the lower yoke of the iron core 1 away from the coil 2. This achieves the effect of providing physical guidance and limiting radial displacement during the assembly of the coil 2, and providing buffering and precise positioning when the coil 2 falls to its final position.

[0032] Reference Figure 3The guide assembly 3 includes an insulating ring 31 and a guide strip 32. The insulating ring 31 extends axially along the core post of the iron core 1 and is sleeved on the core post of the iron core 1, serving to support and fix the guide strip 32. The insulating ring 31 is usually made of a material with good insulation properties, such as epoxy glass cloth board, which not only has good insulation properties but also has a certain strength and stability.

[0033] Reference Figure 3 The guide bar 32 is located on the side of the insulating ring 31 near the coil 2 and is fixedly connected to the insulating ring 31. The side wall of the guide bar 32 away from the core post of the iron core 1 is a smooth arc-shaped guide surface. This design can reduce the friction when the coil 2 is assembled, allowing the coil 2 to slide more smoothly along the guide bar 32. The insulating cardboard inside the coil 2 has a guide groove 33 that matches the guide bar 32. The guide bar 32 and the guide groove 33 cooperate with each other to further limit the radial displacement of the coil 2.

[0034] Reference Figure 3 The guide bar 32 has a semi-circular cross-section, and its radius gradually increases from the top to the bottom of the core post 1. This design makes it easier for the coil 2 to align with the guide bar 32 in the initial assembly stage. As the coil 2 falls, the guide bar 32 and the guide groove 33 fit more tightly, improving the accuracy of the guidance.

[0035] Reference Figure 3 The guide bar 32 is provided with a permanent magnet 321, and the groove wall of the guide groove 33 is provided with a magnetic material layer 331. The magnetic attraction between the permanent magnet 321 and the magnetic material layer 331 can enhance the stability of the guide and ensure that the coil 2 will not easily deviate during the assembly process.

[0036] Reference Figure 3 The combination logic of the guide component 3 is as follows: the insulating ring 31 provides insulation between the iron core 1 and the coil 2 while providing an installation base and support for the guide strip 32; the cooperation between the guide strip 32 and the guide groove 33 achieves physical guidance and radial offset limitation for the coil 2; and the magnetic force of the permanent magnet 321 and the magnetic material layer 331 further enhances the guiding effect. This combination allows the coil 2 to slide accurately along the guide strip 32 during the assembly process, avoiding scratching and collision with the iron core 1 column.

[0037] Reference Figure 4 and Figure 5 The buffer assembly 4 includes a base 41, an elastic buffer post 42, a support platform 43, and a positioning pin 44. The base 41 is located on the side of the lower yoke of the iron core 1 away from the coil 2, providing support for the entire buffer assembly 4. The iron core 1 is fixed on the base 41, and the support platform 43 can slide relative to the iron core 1. The base 41 is usually made of a metal material, such as carbon steel, which has high strength and stability.

[0038] Reference Figure 4 The elastic buffer column 42 includes an outer sleeve 421 disposed on the base 41, an inner sliding column 422 slidably disposed in the outer sleeve 421, and a buffer spring 423 disposed in the outer sleeve 421. One end of the buffer spring 423 is connected to the inner sliding column 422, and the other end of the inner sliding column 422 is connected to the support platform 43.

[0039] Reference Figure 4 A connecting rod 424 is provided at one end of the inner sliding column 422 near the outer sleeve 421. A piston disc 425 is provided on the connecting rod 424. The connecting rod 424 is slidably disposed on the inner sliding column 422. A buffer spring 423 is sleeved on the connecting rod 424. The piston disc 425 is slidably disposed on the inner wall of the outer sleeve 421. A receiving cavity 426 is formed inside the outer sleeve 421 on the side of the piston disc 425 away from the connecting rod 424. A buffer solution is injected into the receiving cavity 426. A pressure relief hole 427 is provided on the piston disc 425.

[0040] Reference Figure 4 When coil 2 falls to its final position, the inner sliding column 422 slides downward under the action of external force, compressing the buffer spring 423. Then the piston disc 425 squeezes the buffer solution, and the buffer solution slowly flows out through the pressure relief hole 427, thereby achieving the buffering effect.

[0041] Reference Figure 4 An installation groove 428 is provided on the inner wall of the outer sleeve 421. A locking block 429 is slidably disposed in the installation groove 428 in the horizontal direction. A locking spring 5 is provided on the side of the locking block 429 away from the inner sliding column 422. The locking spring 5 has the tendency to drive the locking block 429 out of the installation groove 428. A locking groove 6 is provided on the inner sliding column 422. When the coil 2 is installed in place, the locking block 429 extends into the locking groove 6.

[0042] Reference Figure 4 and Figure 5 The locking block 429 is provided with an unlocking rod 7, and the outer wall of the outer sleeve 421 is provided with an unlocking hole 8 that communicates with the mounting groove 428. The unlocking rod 7 extends out of the outer sleeve 421 along the unlocking hole 8, and the locking block 429 can be disengaged from the locking groove 6 by operating the unlocking rod 7.

[0043] Reference Figure 5 The support platform 43 is positioned on top of the elastic buffer column 42 to support the bottom of the coil 2. The support platform 43 is typically made of a metal plate with a smooth, flat surface to ensure that the coil 2 can be placed stably.

[0044] Reference Figure 5 The positioning pin 44 is set on the support platform 43. The insulating end plate at the bottom of the coil 2 is provided with a positioning hole 9 corresponding to the positioning pin 44. The positioning pin 44 extends into the positioning hole 9 to realize the circumferential positioning of the coil 2.

[0045] Reference Figure 4 and Figure 5 The combination logic of the buffer assembly 4 is as follows: the base 41 supports the elastic buffer column 42, which achieves the buffering function through the action of the buffer spring 423 and the buffer solution; the support platform 43 supports the coil 2; the positioning pin 44 cooperates with the positioning hole 9 to achieve circumferential positioning of the coil 2; and the locking block 429 cooperates with the locking groove 6 to lock the coil 2 after it is installed in place. This ensures that the coil 2 is effectively buffered when it falls to its final position, avoiding hard contact with the lower yoke, while achieving precise positioning and installation locking.

[0046] The implementation principle of a high-precision, easily assembled silicon steel transformer according to this application embodiment is as follows: During installation, the upper yoke is first removed from the core 1, then the coils 2 are individually fitted onto the core posts of the core 1, and then the upper yoke is reinstalled on the core 1. Finally, metal clamps are installed to clamp the core 1 and the coils 2. The guide assembly 3, through the cooperation of the guide strip 32 and the guide groove 33, and the magnetic force of the permanent magnet 321 and the magnetic material layer 331, provides accurate physical guidance for the installation of the coils 2, restricts the radial offset of the coils 2, and avoids scratching and collision between the insulation layer of the coils 2 and the silicon steel sheets of the core 1. The buffer assembly 4, through the action of the elastic buffer post 42, the positioning pin 44, and the locking structure, provides buffering and precise positioning when the coils 2 fall to their final position, and achieves installation locking, avoiding hard contact between the coils 2 and the lower yoke, reducing the mechanical stress on the silicon steel sheets of the core 1, ensuring the stability of the magnetic properties of the core 1, and improving the overall performance and long-term operational reliability of the transformer.

[0047] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-precision, easily assembled silicon steel transformer, comprising an iron core (1) formed by stacked silicon steel sheets and a coil (2) sleeved on the core column of the iron core (1), characterized in that: The iron core (1) and the coil (2) are provided with a guide assembly (3) and a buffer assembly (4). The guide assembly (3) is set on the core post surface of the iron core (1) to provide physical guidance and limit radial displacement during the coil (2) assembly process. The buffer assembly (4) is set on the side of the lower yoke of the iron core (1) away from the coil (2) to provide buffering and precise positioning when the coil (2) falls to the final position.

2. The high-precision, easily assembled silicon steel transformer according to claim 1, characterized in that: The guide assembly (3) includes an insulating ring (31) disposed on the core post of the iron core (1) and a plurality of guide strips (32) disposed on the side of the insulating ring (31) near the coil (2). The insulating ring (31) extends axially along the core post of the iron core (1). The guide strips (32) are fixedly connected to the insulating ring (31). The side wall of the guide strips (32) away from the core post of the iron core (1) is a smooth arc-shaped guide surface. The insulating cardboard inside the coil (2) is provided with guide grooves (33) that are adapted to the guide strips (32).

3. A high-precision, easily assembled silicon steel transformer according to claim 2, characterized in that: The cross-section of the guide bar (32) is semi-circular, and the radius of the guide bar (32) gradually increases from the top to the bottom of the iron core (1) column.

4. A high-precision, easily assembled silicon steel transformer according to claim 3, characterized in that: The guide bar (32) is provided with a permanent magnet (321), and the guide groove (33) is provided with a magnetic material layer (331) on the groove wall.

5. A high-precision, easily assembled silicon steel transformer according to claim 1, characterized in that: The buffer assembly (4) includes a base (41) disposed on the side of the lower yoke of the iron core (1) away from the coil (2), an elastic buffer column (42) disposed on the base (41), a support platform (43) disposed on the top of the elastic buffer column (42), and a positioning pin (44) disposed on the support platform (43). The support platform (43) is used to support the bottom of the coil (2). The insulating end plate at the bottom of the coil (2) is provided with a positioning hole (9) corresponding to the positioning pin (44). The positioning pin (44) extends into the positioning hole (9) to realize the circumferential positioning of the coil (2).

6. A high-precision, easily assembled silicon steel transformer according to claim 5, characterized in that: The elastic buffer column (42) includes an outer sleeve (421) disposed on the base (41), an inner sliding column (422) slidably disposed in the outer sleeve (421), and a buffer spring (423) disposed in the outer sleeve (421). One end of the buffer spring (423) is connected to the inner sliding column (422), and the other end of the inner sliding column (422) is connected to the support platform (43).

7. A high-precision, easily assembled silicon steel transformer according to claim 6, characterized in that: The inner sliding column (422) is provided with a connecting rod (424) at one end near the outer sleeve (421). A piston disc (425) is provided on the connecting rod (424). The connecting rod (424) is slidably disposed on the inner sliding column (422). The buffer spring (423) is sleeved on the connecting rod (424). The piston disc (425) is slidably disposed on the inner wall of the outer sleeve (421). A receiving cavity (426) is formed in the outer sleeve (421) on the side of the piston disc (425) away from the connecting rod (424). Buffer solution is injected into the receiving cavity (426). A pressure relief hole (427) is provided on the piston disc (425).

8. A high-precision, easily assembled silicon steel transformer according to claim 7, characterized in that: An installation groove (428) is provided on the inner wall of the outer sleeve (421). A locking block (429) is slidably disposed in the installation groove (428) in the horizontal direction. A locking spring (5) is provided on the side of the locking block (429) away from the inner sliding column (422). The locking spring (5) has the tendency to drive the locking block (429) out of the installation groove (428). A locking groove (6) is provided on the inner sliding column (422). When the coil (2) is installed in place, the locking block (429) extends into the locking groove (6). An unlocking rod (7) is provided on the locking block (429). An unlocking hole (8) communicating with the installation groove (428) is provided on the outer wall of the outer sleeve (421). The unlocking rod (7) extends out of the outer sleeve (421) along the unlocking hole (8).

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