Waterproof structure of electrical junction box of scroll compressor

Abstract

The utility model discloses a kind of electrical junction box waterproof structures of scroll compressor, including machine body and the box body component and cover body component being set on machine body, the annular protruding structure is provided on the back of box body component;The side of cover body component towards box body component is provided with annular groove;Sealing ring is provided in the annular groove;The end surface of cover body component and box body component is assembled connection, and the end surface of box body component is covered in the annular groove after assembly.The annular groove of cover body component and built-in sealing ring form closed cavity in the scheme, the end surface of box body component is completely covered in recess after assembly, and circumferential sealing is realized by sealing ring compression.This structure makes box body and cover body form self-locking type sealing interface, without relying on external fastener to exert pressure.

Description

Technical Field

[0001] This utility model relates to the field of compressor manufacturing technology, and in particular to a waterproof structure for an electrical junction box of a scroll compressor. Background Technology

[0002] As a core component of refrigeration systems, scroll compressors are typically installed and operate outdoors. This outdoor working condition exposes them to the risk of rainwater, condensate, and other liquid water intrusion. Since electrical junction boxes contain live terminals and wires, moisture infiltration can lead to short circuits, electrical leaks, and other electrical safety accidents. Therefore, industry standards require electrical junction boxes to have reliable waterproof sealing performance.

[0003] For example, the "Compressor End Cover Assembly and Scroll Compressor" disclosed in Chinese patent literature, publication number "CN217029296U", includes the following end cover assembly: a compressor end cover with compressor terminals; a terminal protection box covering the compressor terminals and sealingly fitting with the compressor end cover; and an elastic gasket disposed at the connection between the terminal protection box and the compressor end cover. The elastic gasket has a layered structure with a rubber layer covering a metal material layer, and at least one rib protruding towards the terminal protection box is formed on the surface of the layered structure. The rib can elastically deform under the pressure of the terminal protection box, so that its sealing surface is tightly attached to the contact surface with the compressor end cover and the terminal protection box.

[0004] Currently, the waterproof structure of electrical junction boxes for scroll compressors generally adopts a multi-part assembly approach. Common methods include adding a sealing gasket between the box and the compressor body, or applying sealant to fill the gaps. This type of structure relies on additional seals and complex assembly processes. For example, the positioning and installation of the sealing gasket requires precise alignment, and the curing of the sealant requires processing time. This leads to three main drawbacks: First, the increased number of parts raises material costs and supply chain management complexity; second, the assembly process relies on manual operation precision, making it difficult to guarantee consistent sealing quality; third, aging of the sealing gasket or cracking of the sealant can cause water leakage failure, increasing the frequency of maintenance.

[0005] Therefore, there is an urgent need for a compressor electrical junction box connection structure with integrated sealing function to achieve waterproof performance with fewer parts and structural optimization. Utility Model Content

[0006] The primary objective of this invention is to address the issue of component redundancy and failure risks caused by the reliance on additional sealing media in the electrical box 1 of existing scroll compressors. By integrally connecting the annular protrusion on the back of the box with the machine body plane to form a first layer of sealing barrier, and by using the annular groove of the cover to house the sealing ring and embedding the end face of the box into the groove to form a second layer of self-locking sealing structure, the reliance on additional sealing media is reduced, and the basic waterproof function is achieved through the coupling of the two structures.

[0007] The second objective of this invention is to solve the problem of the cumbersome process of assembling electrical box covers using tools, and to achieve tool-free assembly through the interlocking structure of the box body recess and the cover body claw.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A waterproof structure for an electrical junction box of a scroll compressor includes a body and a box assembly and a cover assembly disposed on the body. The back of the box assembly is provided with an annular protrusion structure. The cover assembly is provided with an annular groove on the side facing the box assembly. A sealing ring is disposed in the annular groove. The end face of the cover assembly is assembled and connected to the end face of the box assembly, and after assembly, the end face of the box assembly is covered in the annular groove.

[0009] The root cause of the defects in commonly used sealing solutions is that the box body and the main body rely on gaskets, colloids and other sealing media to block water flow, and the failure of the media directly leads to the collapse of the waterproof function; the lid and the box body also lack an interlocking sealing structure, and the sealing pressure is generated by tightening bolts, which increases the number of fasteners and makes it difficult to balance the pressure distribution.

[0010] In this design, the annular groove of the cover assembly and the built-in sealing ring form a closed cavity. After assembly, the end face of the box assembly is completely covered within the groove, and circumferential sealing is achieved through the compression of the sealing ring. This structure creates a self-locking sealing interface between the box and the cover, eliminating the need for external fasteners to apply pressure. The annular shape of the raised structure facilitates continuous welding, while the groove embedded in the end face eliminates the stringent assembly precision requirements of traditional planar fitting. In this dual sealing mechanism, the raised structure performs the primary sealing function, while the groove coverage provides vibration compensation. Together, they address the dependence of traditional seals on common auxiliary media such as gaskets and colloids.

[0011] Preferably, the cover assembly has claws on both sides, and the box assembly has recesses on both sides that mate with the claws, with the claws fitting into the recesses. The engagement of the claws and the recesses on the cover assembly constitutes a mechanical self-locking mechanism. The elastic deformation characteristics of the claws cause them to radially contract when pressed into the recesses, and return to their original shape after reaching the desired position, forming an interference lock. This structure replaces the threaded holes and fasteners required for bolted connections, and the assembly process can be completed without tools. The beveled surface at the joint between the claws and the recesses converts vibration loads into radial clamping force, avoiding the risk of axial loosening. Compared to bolted connections that require multiple tightening steps, this solution achieves reliable fixation through a single pressing action, significantly improving assembly efficiency and reducing component complexity.

[0012] Preferably, the annular protrusion structure is welded to the welding surface of the machine body via resistance welding. The connection between the annular protrusion structure and the welding surface via resistance welding melts the metal at the contact surface, forming a metallurgical bonding layer. The welding process establishes a continuous metal-sealed interface between the protrusion structure and the machine body, completely eliminating the interface penetration path present in traditional gaskets. The weld strength of the resistance weld is close to that of the base material, ensuring the structural integrity of the sealing interface under compressor vibration conditions. Simultaneously, it avoids the curing time of the sealant, achieving a simultaneous improvement in production cycle time and reliability.

[0013] Preferably, a wiring hole is provided on the lower side of the housing assembly. The wiring hole's location on the lower side of the housing assembly allows the power cord to hang naturally. This layout utilizes gravity to guide condensate outwards along the wires, preventing liquid from flowing back into the housing. The smooth edge of the hole prevents cable abrasion, and the hole's location away from the bottom of the housing creates a water-retaining zone. Compared to top-mounted or side-mounted wiring holes, which require additional waterproofing structures, this solution achieves physical water resistance through spatial positioning, simplifying the wire inlet sealing solution.

[0014] Preferably, the housing assembly includes an electrical box, on which the annular protrusion structure and wiring holes are disposed. The electrical box, as the core carrier of the housing assembly, has the annular protrusion structure integrally formed with the housing body through stamping. This one-piece structure eliminates the seam defects of separate assembly, ensuring the flatness and contour accuracy of the protrusion ring. The continuous distribution of the one-piece metal streamlines gives the root of the protrusion structure higher fatigue resistance, adapting to compressor vibration conditions.

[0015] Preferably, the cover assembly includes an electrical box cover, on which the annular groove is disposed. The electrical box cover is manufactured by injection molding, and the geometric accuracy of the annular groove is directly guaranteed by the mold. The depth and width of the groove match the size of the sealing ring, forming a stable compression space. The insulating properties of the plastic material block leakage paths, while the injection molding process ensures a seamless transition between the sidewalls and bottom surface of the groove, ensuring uniform deformation of the sealing ring within the groove and avoiding seal failure caused by localized stress concentration.

[0016] Preferably, the sealing ring is an O-ring rubber ring, embedded in the annular groove. After being embedded in the groove, the O-ring rubber ring generates radial elastic compression, forming a continuous sealing band on the end face of the box. The resilience of the rubber sealing ring compensates for dimensional fluctuations caused by temperature changes, and the circular cross-section maintains pressure equilibrium under vibration. This sealing method improves the tolerance to end face machining errors.

[0017] Preferably, the housing is provided with a terminal block, which is resistance welded to the housing and located inside the housing assembly. The terminal block is horizontally welded to the central area of ​​the housing, within the enclosed space of the housing assembly. This arrangement completely seals the live components within a waterproof environment, and the welded connection ensures reliable electrical conductivity. The terminal block extends outward from the side wall of the housing, preventing short-circuit risks from contact with the cover.

[0018] Preferably, the electrical box is a low-carbon steel sheet component formed by stamping, and the annular protrusion structure is integrally formed by stamping. The electrical box is made of low-carbon steel sheet by stamping, and the material's ductility ensures that the protrusion structure does not crack during plastic deformation. The stamping process creates a gradually rounded corner at the root of the protrusion, resulting in a stress distribution superior to machined structures. Integral forming eliminates the weakening problem of the weld heat-affected zone and improves the long-term stability of the sealing interface.

[0019] Preferably, the electrical box cover is an injection-molded insulating plastic part, and the annular groove is integrally formed by injection molding. The electrical box cover is made of insulating engineering plastic injection molding, and its coefficient of thermal expansion matches that of the metal box body. The injection molding process forms a dense skin layer on the surface of the groove, preventing media penetration.

[0020] Therefore, this utility model has the following beneficial effects.

[0021] The raised section on the back of the box is directly welded to the body to form a metal sealing layer, eliminating the risk of aging and leakage of the sealing gasket used in traditional technology and solving the problem of dependence on traditional media.

[0022] The groove of the cover covers the end face of the box and squeezes the sealing ring, which is used to achieve self-adjusting sealing pressure under vibration, thus overcoming the sealing failure caused by loose bolts.

[0023] The interlocking of the jaws and the beveled recess enables tool-free assembly, which reduces the number of parts and shortens the working time compared to bolted connections, while also reducing the complexity of the production process. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of this utility model.

[0025] Figure 2 This is a top view of the present invention.

[0026] Figure 3 yes Figure 2 A cross-sectional view at point AA.

[0027] Figure 4 yes Figure 3 A magnified view of point I in the mid-section.

[0028] Figure 5 This is a structural schematic diagram of the electrical box in this utility model.

[0029] Figure 6 This is a schematic diagram of the electrical box cover in this utility model.

[0030] Figure 7 This is a schematic diagram of the O-ring structure in this utility model.

[0031] In the diagram: Electrical box 1, annular protrusion 1a, recess 1b, wiring hole 1c, box end face 1d, O-ring 2, electrical box cover 3, claw 3a, annular groove 3b, body 4, terminal block 5. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1 like Figure 1 , 2 As shown in Figures 3 and 5, this embodiment proposes a waterproof structure for an electrical junction box of a scroll compressor, including a body 4 and a box assembly and a cover assembly disposed on the body 4. The box assembly has an annular protrusion 1a on its back side; the cover assembly has an annular groove 3b on its side facing the box assembly; a sealing ring is disposed within the annular groove 3b; the cover assembly is assembled to the end face of the box assembly, and after assembly, the end face of the box assembly is covered within the annular groove 3b. The cover assembly has claws 3a on both sides, and the box assembly has recesses 1b on both sides that mate with the claws 3a, with the claws 3a fitted into the recesses 1b. The box assembly includes an electrical box 1, and the cover assembly includes an electrical box cover, with the annular groove 3b disposed on the electrical box cover. The sealing ring is an O-ring rubber ring embedded within the annular groove 3b. The body 4 is provided with a terminal 5, which is welded to the body 4 by resistance welding and is located inside the box assembly.

[0034] The engagement of the cover assembly's claw 3a with the box's recess 1b constitutes a mechanical self-locking mechanism. The elastic deformation characteristics of the claw 3a cause it to radially contract when pressed into the recess 1b, returning to its original shape upon reaching the desired position, forming an interference lock. This structure replaces the threaded holes and fasteners required for bolted connections, allowing for tool-free assembly. The beveled surface at the junction of the claw 3a and the recess 1b converts vibration loads into radial clamping force, preventing axial loosening. Compared to bolted connections requiring multiple tightening steps, this solution achieves reliable fixation through a single pressing action, significantly improving assembly efficiency and reducing component complexity. The electrical box cover is manufactured using injection molding, with the geometric precision of the annular groove 3b directly guaranteed by the mold. The groove depth and width match the sealing ring size, creating a stable compression space. The insulating properties of the plastic material block leakage paths, while the injection molding process ensures a seamless transition between the groove sidewalls and the bottom surface, guaranteeing uniform deformation of the sealing ring within the groove and preventing seal failure due to localized stress concentration. The O-ring, embedded in the groove, generates radial elastic compression, forming a continuous sealing band on the box's end face 1d. The rubber sealing ring's resilience compensates for dimensional fluctuations caused by temperature changes, and its circular cross-section maintains pressure equilibrium under vibration. This sealing method improves tolerance to end-face machining errors. Terminal 5 is horizontally welded to the center area of ​​the body 4, located within the enclosure space of the housing assembly. This layout completely seals the live components within a waterproof environment, and the welded connection ensures reliable electrical conductivity.

[0035] Specifically, the body 4 serves as the mounting platform, and its welding surface is precision-machined to ensure flatness. The annular protrusion 1a on the back of the housing assembly is a continuous closed ring, with its height optimized to accommodate the weld pool. The lower surface of this protrusion is metallurgically bonded to the welding surface of the body 4 through resistance welding. During the welding process, the current causes the metals at the contact surface to melt and interpenetrate, forming a seamless metal sealing layer after cooling. The annular shape ensures the continuity of the sealing path, avoiding the risk of seam leakage associated with traditional split-type gaskets.

[0036] like Figure 4 , 6 As shown in Figure 7, a terminal block 5 is horizontally positioned in the central area of ​​the internal space of the housing assembly. The terminal block 5 is fixed to the housing 4 by resistance welding. Wiring space is provided around the circumference of the terminal block, so that the live parts are located in the core area of ​​the sealed environment.

[0037] The annular groove 3b of the cover assembly is a rectangular cross-section channel, with its depth matching the diameter of the sealing ring. The O-ring is pre-compressed and embedded at the bottom of the groove, with its free height slightly greater than the groove depth. When the cover assembly is assembled with the box assembly, the box end face 1d is completely submerged in the groove, forcing the O-ring 2 to undergo radial compression deformation. At this time, the top surface of the box end face 1d fits against the bottom surface of the groove to form the first sealing surface, the sidewall of the end face and the inner sidewall of the groove form a narrow gap to create a second labyrinth seal, and the elastic filling of the O-ring 2 establishes a third dynamic seal.

[0038] The height of the outer wall of the groove exceeds the thickness of the box end face by 1d, forming a suspended water-blocking structure. This eave-like edge directly blocks vertically falling liquid while guiding the liquid to flow downwards along the outer wall. A guide slope is provided at the bottom of the groove to allow the trace amount of liquid that seeps into the groove to be discharged to the outside.

[0039] In the assembled state, the end face 1d of the housing is completely within the groove-enclosed space, forming a triple sealing barrier: the metal welded layer isolates water seepage from the four sides of the housing, the O-rings prevent external liquid intrusion, and the built-in terminal block 5 prevents moisture from contacting live parts. Each sealing level is based on a different physical mechanism: the welded layer relies on the bonding of metal molecules, the labyrinth seal uses fluid paths to block flow, and the elastic seal compensates for deformation through material rebound.

[0040] On the compressor assembly line, the operator first fixes the machine body 4 onto the welding fixture positioning base, ensuring the welding surface is horizontal. Then, the electrical box 1 is taken and its annular protrusion 1a on the back is aligned with the welding surface of the machine body 4. The upper and lower electrodes of the resistance welding machine press against the top surface of the protrusion ring and the bottom surface of the machine body 4 respectively, and a set current is applied to instantly melt the metal at the contact interface. The molten metal permeates under electrode pressure and forms a seamless metallurgical bonding layer after cooling. During the welding process, the heat is strictly controlled within the local area of ​​the protrusion ring to prevent overall thermal deformation of the box body.

[0041] After welding is completed, the operator places terminal 5 horizontally in the designated position on the body 4 and fixes it using resistance welding. The weld point is located at the contact surface between the base of terminal 5 and the body 4, where molten metal fills the microscopic gaps to form a conductive path. At this time, the top of terminal 5 is kept within a safe distance shorter than that of the electrical box cover.

[0042] The assembly process for the electrical box cover is performed independently: The operator manually inserts the O-ring into the bottom of the annular groove 3b on the cover body, using the elasticity of the rubber to temporarily fix it in the groove. Then, holding the cover assembly with both hands, the operator aligns the opening end of the groove with the end face of the electrical box and presses it down. As the end face 1d of the box body gradually sinks into the groove, the O-ring 2 experiences continuous radial compression, generating a rebound force that ensures a tight fit between the end face 1d of the box body and the bottom surface of the groove. When the cover is fully in place, the end face 1d of the box body is circumferentially covered by the groove, and the compression of the O-ring 2 reaches a stable working state.

[0043] Example 2 like Figure 6As shown, this embodiment discloses a waterproof structure for an electrical junction box of a scroll compressor, including a body 4 and a box assembly and a cover assembly disposed on the body 4. The box assembly has an annular protrusion 1a on its back side; the cover assembly has an annular groove 3b on its side facing the box assembly; a sealing ring is disposed within the annular groove 3b; the cover assembly is assembled to the end face of the box assembly, and after assembly, the end face of the box assembly is covered within the annular groove 3b. The cover assembly has claws 3a on both sides, and the box assembly has recesses 1b on both sides that mate with the claws 3a, with the claws 3a fitted into the recesses 1b.

[0044] In this design, the annular groove 3b of the cover assembly forms a closed cavity with the built-in sealing ring. After assembly, the end face of the box assembly is completely enclosed within the groove, achieving circumferential sealing through the compression of the sealing ring. This structure creates a self-locking sealing interface between the box and the cover, eliminating the need for external fasteners to apply pressure. The annular shape of the raised structure facilitates continuous welding, while the end face embedded in the groove eliminates the stringent assembly precision requirements of traditional planar fitting. In this dual sealing mechanism, the raised structure performs the primary sealing function, while the groove provides vibration compensation, collaboratively addressing the dependence of traditional seals on common auxiliary media such as gaskets and colloids. The elastic deformation characteristics of the claw 3a cause it to radially contract when pressed into the recess 1b, returning to its original shape after reaching its final position to form an interference lock. This structure replaces the threaded holes and fasteners required for bolted connections, allowing for tool-free assembly. The beveled surface at the junction of the claw 3a and the recess 1b converts vibration loads into radial clamping force, preventing the risk of axial loosening. Compared to bolted connections which require multiple tightening steps, this solution achieves reliable fixing through a single press-in action, significantly improving assembly efficiency and reducing part complexity.

[0045] A wiring hole 1c is provided on the lower side of the box assembly. The box assembly includes an electrical box 1, and the annular protrusion structure 1a and the wiring hole 1c are disposed on the electrical box 1. The wiring hole 1c is located on the lower side of the box assembly, allowing the power cord to hang naturally, guiding condensate water to flow outward along the wire and preventing liquid from flowing back into the box. The edge of the hole is smoothly treated to prevent cable wear, and the hole position is far from the bottom of the box to form a water-isolation zone. Compared with top-mounted or side-mounted wiring holes 1c, which require additional waterproofing structures, this solution achieves physical water blocking through spatial positioning, simplifying the wire inlet sealing solution. The electrical box 1, as the core carrier of the box assembly, has the annular protrusion structure 1a integrally formed with the box body by stamping. The one-piece structure eliminates the seam defects of split assembly, ensuring the flatness and contour accuracy of the protrusion ring. The continuous distribution of the one-piece metal streamlines gives the root of the protrusion structure higher fatigue resistance, adapting to the vibration conditions of the compressor.

[0046] In this embodiment, the electrical box 1 is a low-carbon steel plate part formed by stamping, and the annular protrusion structure 1a is integrally formed by stamping. The electrical box 1 is made of low-carbon steel plate by stamping, and the material's ductility ensures that the protrusion structure does not crack during plastic deformation. The stamping process creates a gradually rounded corner at the root of the protrusion, resulting in a stress distribution superior to machined structures. Integral forming eliminates the weakening problem of the weld heat-affected zone, improving the long-term stability of the sealing interface. The electrical box cover is an insulating plastic part formed by injection molding, and the annular groove 3b is integrally formed by injection molding. The electrical box cover is made of insulating engineering plastic by injection molding, and its coefficient of thermal expansion matches that of the metal box body. The injection molding process forms a dense skin layer on the surface of the groove, preventing media penetration.

[0047] Specifically, the electrical box 1, as the core component of the box assembly, has an annular protrusion structure 1a integrally formed with the box body through a stamping process. During the stamping process, the metal sheet undergoes plastic flow within the mold, forming a gradually rounded transition zone at the root of the protrusion to avoid stress concentration. The height of the protrusion ring is optimized to ensure controllable welding penetration, and its top surface remains flat to accommodate resistance welding electrodes. A wiring hole 1c is opened on the lower part of the side of the box. The wiring hole 1c is located on the lower part of the side wall of the box. After the power cord is inserted, it hangs naturally, and the liquid film formed on the surface of the wire flows out of the hole under the action of gravity. The air inside the hole communicates with the external environment, forming a slight positive pressure difference, which prevents the backflow and seepage of external liquid through the pressure difference.

[0048] The annular groove 3b of the electrical box cover is integrally formed through injection molding, with the groove depth matching the diameter of the sealing ring cross-section. A water-retaining eave structure extends from the outer wall of the groove, and the outward-curving angle of the eaves diverts falling liquid outwards due to surface tension. The width of the groove bottom is slightly larger than the diameter of the sealing ring, allowing for deformation space to accommodate the thermal expansion of the rubber. The claws 3a on both sides of the cover are injection molded simultaneously with the cover body. The thickened design at the base of the claws enhances their elasticity and strength, and the guide bevel at the tips facilitates assembly and insertion.

[0049] The chuck 3a engages with the recess 1b of the electrical box 1. The recess 1b is a rectangular cavity, its depth exceeding the maximum thickness of the chuck 3a. The inner bevel of the chuck 3a forms an acute angle with the horizontal plane. When the chuck tip contacts the edge of the recess 1b's entrance, the bevel converts the vertical downward pressure into a radial contraction force. After entering the recess 1b, the chuck elastically recovers, and the chuck tip hooks onto the bottom edge of the recess 1b, forming a mechanical interlock. This structure allows the chuck root to absorb energy through elastic deformation when the cover is subjected to vibration loads, preventing loosening due to hard impacts.

[0050] In the assembled state, the stamped metal protrusion ring of the electrical box 1 is fused with the welding plane of the body 4 to form a permanent metal sealing layer. The groove of the cover completely covers the end face 1d of the box, and the O-ring 2 fills the microscopic gap between the end face 1d of the box and the groove under compression. The engagement of the claw 3a and the recess 1b causes the cover to continuously apply axial pressure to the box, and the pressure is transmitted to the sealing ring through the end face 1d of the box, maintaining a constant compression.

Claims

1. A waterproof structure for an electrical junction box of a scroll compressor, comprising a body and a box assembly and a cover assembly disposed on the body, characterized in that: The back of the box assembly has an annular protrusion; the side of the cover assembly facing the box assembly has an annular groove; a sealing ring is provided in the annular groove; the end faces of the cover assembly and the box assembly are assembled and connected, and after assembly, the end face of the box assembly is covered in the annular groove.

2. The waterproof structure according to claim 1, characterized in that: The cover assembly has claws on both sides, and the box assembly has recesses on both sides that are adapted to the claws, with the claws fitted into the recesses.

3. The waterproof structure according to claim 1, characterized in that: The annular protrusion structure is welded to the welding surface of the machine body by resistance welding.

4. The waterproof structure according to claim 1, characterized in that: A wiring hole is provided on the lower side of the box assembly.

5. The waterproof structure according to claim 4, characterized in that: The housing assembly includes an electrical box, and the annular protrusion structure and wiring holes are disposed on the housing assembly.

6. The waterproof structure according to claim 1, characterized in that: The cover assembly includes an electrical box cover, and the annular groove is disposed on the electrical box cover.

7. The waterproof structure according to any one of claims 1-6, characterized in that: The sealing ring is an O-ring rubber ring, which is embedded in the annular groove.

8. The waterproof structure according to claim 1, characterized in that: The body is provided with a terminal block, which is welded to the body by resistance welding and is located inside the box assembly.

9. The waterproof structure according to claim 5, characterized in that: The electrical box is a low-carbon steel plate part formed by stamping, and the annular protrusion structure is integrally formed and connected to the electrical box by stamping.

10. The waterproof structure according to claim 6, characterized in that: The electrical box cover is an injection-molded insulating plastic part, and the annular groove is integrally formed and connected to the electrical box cover by injection molding.

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