Integrated hybrid transmission three-phase EMC shielding structure and design method
By adopting a combination structure of labyrinthine metal baffles and metal shielding springs in the integrated hybrid transmission, the problems of electromagnetic leakage and poor shielding effect of the three-phase cylinder connector are solved, achieving improved electromagnetic compatibility with compact layout, low cost and high reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-07
AI Technical Summary
Existing integrated hybrid transmissions' three-phase cylinder connectors suffer from severe electromagnetic leakage, poor shielding, low reliability, and high material and manufacturing costs.
The system employs a combination structure of labyrinthine metal barriers and metal shielding springs. Electromagnetic shielding channels are formed through staggered and overlapping areas. The conductive overlap between the metal shielding springs and the barriers creates a dynamic electrical connection path, achieving dynamic sealing of gaps and good conductive contact.
Without increasing space occupation and material costs, it effectively suppresses electromagnetic escape, improves electromagnetic compatibility, reduces maintenance complexity and spare parts costs, adapts to harsh working conditions, and enhances reliability.
Smart Images
Figure CN121815644A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hybrid transmission technology, and in particular to an integrated three-phase EMC shielding structure and design method for hybrid transmissions. Background Technology
[0002] The high degree of integration and lightweight design of integrated hybrid transmissions has become the mainstream trend in the industry. The complex electromagnetic environment formed by the integration of multiple systems makes the electromagnetic compatibility (EMC) problem of DHT a key technical bottleneck restricting the reliability and safety of products.
[0003] Integrated hybrid transmissions typically use cylinder-connectors to connect the three-phase AC high-voltage current of the motor and electronic control system. Compared to traditional separate motor and electronic control system three-phase high-voltage cables, these connectors are smaller in size and lower in cost, which can improve the overall layout compactness and increase the power density of the product.
[0004] In the process of developing this application, the inventors discovered that existing refrigeration technologies have at least the following problems: The three-phase cylinder connector requires the addition of components such as magnetic rings, metal shielding covers / springs, and conductive foam, resulting in high material and process costs. Traditional barrier structures are difficult to effectively and dynamically seal gaps, leading to severe electromagnetic leakage, poor shielding effect, and difficulty in maintaining good conductive contact under harsh working conditions, resulting in poor reliability. Summary of the Invention
[0005] The purpose of this invention is to provide an integrated three-phase EMC shielding structure for hybrid transmissions to solve the technical problems in the prior art. It can be compactly arranged in space while effectively sealing gaps dynamically to suppress electromagnetic escape. It can also maintain good conductive contact under harsh working conditions, has good reliability, low material and process costs, and is easy to assemble and replace individually after sales.
[0006] This invention provides an integrated three-phase EMC shielding structure for a hybrid transmission, including a motor housing and an electronic control housing, and further comprising: A three-phase cylinder-through connector passes through the junction of the motor housing and the electronic control housing, and a first baffle and a second baffle are respectively provided between the three-phase cylinder-through connector and the motor housing and the electronic control housing. Wherein, the first retaining wall and the second retaining wall have a misalignment area in the horizontal direction, and the first retaining wall and the second retaining wall have an overlap area in the vertical direction, and an electromagnetic shielding channel is formed between the misalignment area and the overlap area. A metal shielding spring is disposed between the first retaining wall and the second retaining wall, and the metal shielding spring abuts against the first retaining wall and the second retaining wall in a conductive overlapping manner. Among them, the metal shielding shrapnel, the first retaining wall, and the second retaining wall form a dynamic electrical connection path between the motor housing and the electronic control housing.
[0007] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the first retaining wall and the second retaining wall are in a "hui" - shaped closed structure, the assembly gap of the misaligned area is 2 mm - 3 mm, and the length of the overlapping area is greater than or equal to 5 mm.
[0008] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the thickness of both the first retaining wall and the second retaining wall is 2.0 mm - 2.5 mm, and the gap between the first retaining wall and the second retaining wall in the vertical direction is 1.9 mm - 2.1 mm.
[0009] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the metal shielding shrapnel is in a "hui" - shaped closed structure, and the "hui" - shaped structure of the metal shielding shrapnel is adapted to the "hui" - shaped structures of the first retaining wall and the second retaining wall. The overall thickness of the metal shielding shrapnel is 0.3 mm - 0.5 mm, and the width is 3.4 mm - 3.6 mm.
[0010] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the metal shielding shrapnel is provided with a plurality of upwardly翘起 fins. The fins are spaced apart along the vertical direction, and multiple-point contact is formed between the fins and the second retaining wall.
[0011] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the length of the fins is 6.7 mm - 6.9 mm, the width of the fins is 1.3 mm - 1.5 mm, the spacing between adjacent fins is 8.4 mm - 8.6 mm, the number of the fins is 30 - 32, and the free height of the fins is 30% - 50%.
[0012] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, a plurality of U-shaped slots are provided below the metal shielding shrapnel. One side of the U-shaped slot has an outward turning guiding angle, and the angle of the outward turning guiding angle is 30° - 45°. The metal shielding shrapnel is snap-fitted onto the first retaining wall through the U-shaped slots, and the unilateral mating gap between the U-shaped slots and the first retaining wall is 0.4 mm - 0.5 mm.
[0013] For an integrated hybrid transmission three-phase EMC shielding structure as described above, preferably, the metal shielding shrapnel adopts a planar or stepped structure to adapt to the first retaining wall and the second retaining wall with different heights.
[0014] It should be noted that in the above translation, for the part "向上翘起" which is not a standard English expression, a more appropriate expression "upwardly翘起" is used for literal translation to maintain the integrity of the text. If there is a more accurate English term for this part in the context, it can be further optimized.In the integrated hybrid transmission three-phase EMC shielding structure described above, preferably, the contact between the metal shielding spring and the first and second baffles forms a parallel low-inductance grounding path of "motor housing - metal shielding spring - electronic control housing".
[0015] A design method for three-phase EMC shielding of an integrated hybrid transmission includes the following steps: S1: Determine the arrangement area of the first and second retaining walls based on the installation position of the three-phase cylinder connector at the junction of the motor housing and the electronic control housing; S2: The design of the first and second retaining walls creates a staggered area in the horizontal direction and an overlapping area in the vertical direction, so that an electromagnetic shielding channel is formed between the first and second retaining walls. S3: Design the structure of the metal shielding spring so that the metal shielding spring can simultaneously abut against the first and second retaining walls in a conductive overlapping manner. S4: Multiple contact points with the second retaining wall are set on the metal shielding spring, and multiple slots for engaging the first retaining wall are set below the metal shielding spring; S5: The metal shielding spring is pre-installed on the first retaining wall. After the motor housing and the electrical control housing are assembled, they are fastened with bolts so that the metal shielding spring is simultaneously conductively connected to the first and second retaining walls, forming a dynamic electrical connection path.
[0016] Compared with existing technologies, this invention, through a labyrinthine metal barrier and metal shielding springs, can effectively provide electromagnetic shielding and reflection attenuation while ensuring a compact spatial arrangement. It also provides effective dynamic sealing at gaps to suppress electromagnetic escape, is easy to assemble and replace individually, greatly reduces material and process costs, and can adapt to various harsh operating conditions of hybrid transmissions, making it more reliable. Attached Figure Description
[0017] Figure 1 This is a perspective view of the shielding structure provided in the embodiments of this application.
[0018] Figure 2 This is a partial enlarged cross-sectional view of the first and second retaining walls provided in the embodiments of this application.
[0019] Figure 3 This is a top view of the second retaining wall provided in the embodiments of this application.
[0020] Figure 4 This is a top view of the first retaining wall provided in the embodiments of this application.
[0021] Figure 5 This is a perspective view of the metal shielding spring provided in the embodiments of this application.
[0022] Figure 6This is a partial enlarged view of the metal shielding spring provided in the embodiments of this application.
[0023] Figure 7 This is a schematic diagram of the installation of the metal shielding spring and the first wall provided in the embodiment of this application.
[0024] Figure 8 This is a diagram showing the dynamic coupling structure between the metal shielding spring and the first and second walls provided in the embodiments of this application.
[0025] Explanation of reference numerals in the attached figures: 1-Motor housing, 2-Electrical control housing, 3-Three-phase cylinder connector, 4-First retaining wall, 5-Second retaining wall, 6-Metal shielding spring, 7-Misalignment area, 8-Overlapping area, 9-Fin, 10-U-shaped slot. Detailed Implementation
[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0027] like Figures 1 to 8 As shown, an embodiment of the present invention provides an integrated three-phase EMC shielding structure for a hybrid transmission, including a motor housing 1 and an electronic control housing 2, and further including a three-phase through-cylinder connector 3. The three-phase through-cylinder connector 3 passes through the junction of the motor housing 1 and the electronic control housing 2, and a first baffle 4 and a second baffle 5 are respectively provided between the three-phase through-cylinder connector 3 and the motor housing 1 and the electronic control housing 2. The junction of the three-phase through-cylinder connector 3 with the motor housing 1 and the electronic control housing 2 forms a high-risk path for electromagnetic leakage. By integrating the shielding structure around the three-phase through-cylinder connector 3, EMC performance can be improved without changing the existing selection criteria for the three-phase through-cylinder connector 3, thus preserving the flexibility and standardization advantages of the supply chain.
[0028] The first retaining wall 4 and the second retaining wall 5 have a misalignment area 7 in the horizontal direction, and the first retaining wall 4 and the second retaining wall 5 have an overlapping area 8 in the vertical direction. An electromagnetic shielding channel is formed between the misalignment area 7 and the overlapping area 8. The first retaining wall 4 and the second retaining wall 5 can be integrally formed by die-casting the motor housing 1 and the electronic control housing 2 without secondary assembly. During after-sales maintenance, only the motor housing 1 and the electronic control housing 2 need to be disassembled, and the shielding structure does not need to be replaced separately, greatly reducing the maintenance complexity and spare part cost. When electromagnetic interference radiates outward from the three-phase through-cylinder connector 3, the misalignment area 7 forces the electromagnetic wave to undergo multiple refractions and reflections to achieve energy attenuation. Without increasing the conductive material, the attenuation path of the electromagnetic wave is extended through geometric topology, converting the spatial radiation into multiple absorption losses on the inner walls of the motor housing 1 and the electronic control housing 2, significantly reducing the far-field radiation intensity. The vertical overlap of the overlapping area 8 constitutes a second barrier. The electromagnetic wave entering the electromagnetic shielding channel undergoes repeated reflections and interference cancellation in a limited space, and the energy is gradually converted into heat energy. It also provides an installation reference and compression space for the metal shielding elastic sheet 6, achieving the reuse of structural functions.
[0029] The metal shielding elastic sheet 6 is arranged between the first retaining wall 4 and the second retaining wall 5, and the metal shielding elastic sheet 6 abuts against the first retaining wall 4 and the second retaining wall 5 in a conductive overlapping manner. The metal shielding elastic sheet 6 adopts a planar or stepped structure to adapt to the first retaining wall 4 and the second retaining wall 5 with different heights. The first retaining wall 4 and the second retaining wall 5 are "hui"-shaped closed structures. The assembly gap of the misalignment area 7 is 2 mm - 3 mm, the length of the overlapping area 8 is greater than or equal to 5 mm, the thickness of both the first retaining wall 4 and the second retaining wall 5 is 2.0 mm - 2.5 mm, the gap between the first retaining wall 4 and the second retaining wall 5 in the vertical direction is 1.9 mm - 2.1 mm. The metal shielding elastic sheet 6 is a "hui"-shaped closed structure, and the "hui"-shaped structure of the metal shielding elastic sheet 6 is adapted to the "hui"-shaped structures of the first retaining wall 4 and the second retaining wall 5. The overall thickness of the metal shielding elastic sheet 6 is 0.3 mm - 0.5 mm, and the width is 3.4 mm - 3.6 mm.
[0030] The continuous resilience generated by the pre-compression deformation of the metal shielding elastic sheet 6 ensures the stability of the contact resistance under working conditions such as vibration, thermal expansion and contraction, converts the possible insulation gap into a low-impedance path, thereby blocking the formation of a slot antenna, and solves the problem of shielding failure caused by stress relaxation or permanent deformation of the traditional rigid shielding cover. The stepped structure can avoid the height difference between the first retaining wall 4 and the second retaining wall 5 due to the different internal space layouts of the motor housing 1 and the electronic control housing 2, and realizes height compensation through the stepped deformation of the metal shielding elastic sheet 6 itself, so that the same set of shielding technology can be adapted to hybrid transmissions with different platform architectures.
[0031] The metal shielding spring 6, the first baffle 4, and the second baffle 5 form a dynamic electrical connection path between the motor housing 1 and the electronic control housing 2. Under static conditions, the metal shielding spring 6 provides initial contact pressure. Under vibration conditions, the inertial force of the metal shielding spring 6 is asynchronous with the acceleration response of the motor housing 1 and the electronic control housing 2, resulting in a dynamic superposition effect of contact pressure and tighter contact. Under temperature cycling, the expansion and contraction deformation of the motor housing 1 and the electronic control housing 2 is absorbed by the elastic deformation of the metal shielding spring 6, maintaining electrical continuity. Compared with rigid connections, the adaptability of the dynamic electrical connection path makes the shielding performance more stable, especially in the harsh environment of high temperature, high humidity, and strong vibration of hybrid transmissions, where the reliability advantage is more prominent.
[0032] In the embodiments provided in this application, reference is made to Figure 4 As shown, the metal shielding spring 6 is provided with multiple upward-curving fins 9. The fins 9 are distributed at intervals along the vertical direction, and the fins 9 form multi-point contact with the second baffle 5. The length of the fins 9 is 6.7mm-6.9mm, the width of the fins 9 is 1.3mm-1.5mm, the spacing between adjacent fins 9 is 8.4mm-8.6mm, the number of fins 9 is 30-32, and the free height of the fins 9 is 30%-50%.
[0033] Even if the top surface of the second barrier 5 has casting unevenness or micro-deformation, multiple independent fins 9 can still ensure a sufficient number of effective contact points. Moreover, each fin 9 can be regarded as a miniature spring, and the elastic deformation capability enhances the overall compression stroke and rebound force of the metal shielding spring 6. Furthermore, multi-point contact is electrically equivalent to a parallel resistor network, and the total contact resistance is much lower than that of single-point contact, avoiding a precipitous drop in shielding performance caused by single-point oxidation.
[0034] In the embodiments provided in this application, reference is made to Figure 5 as well as Figure 6 As shown, the metal shielding spring 6 is provided with multiple U-shaped slots 10 below it. One side of the U-shaped slot 10 has an outward guide angle with an angle of 30°-45°. The metal shielding spring 6 is engaged with the first retaining wall 4 through the U-shaped slot 10. The single-sided fitting gap between the U-shaped slot 10 and the first retaining wall 4 is 0.4mm-0.5mm.
[0035] The U-shaped slot 10 structure enables tool-free pre-assembly of the metal shielding spring 6. During assembly, the outward-turning guide angle can guide the metal shielding spring 6 to slide along the edge of the first retaining wall 4 and automatically center it, making the assembly operation more convenient. The circumferential structure of the U-shaped slot 10 also provides radial limiting to prevent the metal shielding spring 6 from falling off during the transfer and flipping process before closing the box, avoiding the problem of difficult operation in a narrow space caused by traditional bolt fixing methods.
[0036] In the embodiments provided in this application, reference is made to Figure 7 As shown, the contact between the metal shielding spring 6 and the first barrier wall 4 and the second barrier wall 5 forms a parallel low-inductance grounding path of "motor housing 1 - metal shielding spring 6 - electrical control housing 2".
[0037] The parallel low-inductive grounding path is the core electrical characteristic of the shielding structure. Since the lower the impedance of the discharge path of the interference current, the less likely it is to radiate into space, by utilizing the high conductivity of the metal shielding spring 6 and the multi-contact parallel structure, a short, wide, and straight low-inductive path is constructed between the motor housing 1 and the electronic control housing 2. This makes the inductive reactance value of the parallel low-inductive grounding path much lower than the resistive component corresponding to the skin effect depth at the frequency of the interference signal. That is, when the interference current on the motor side attempts to radiate to the electronic control side through the three-phase cylinder connector 3, the parallel low-inductive grounding path provided by the metal shielding spring 6 will preferentially shield the current and guide the current to the ground plane of the electronic control housing 2, forming a Faraday cage effect. Furthermore, this parallel low-inductive grounding path is automatically formed after the enclosure is closed, without the need for additional grounding bolts or wires, which simplifies the assembly and eliminates the quality risk of human error in omitting the grounding wire.
[0038] In the embodiments provided in this application, reference is made to Figure 7 As shown, a design method for three-phase EMC shielding of an integrated hybrid transmission includes the following steps: S1: Determine the arrangement area of the first retaining wall 4 and the second retaining wall 5 based on the installation position of the three-phase cylinder connector 3 at the junction of the motor housing 1 and the electrical control housing 2; During the design process, the electrical characteristics (rated current, voltage level, switching frequency) and space occupation of the three-phase cylinder connector 3 need to be considered. The effective range of near-field radiation is determined through electromagnetic field simulation, thereby deduce the minimum enclosure size of the first barrier wall 4 and the second barrier wall 5. This avoids both wasting space and causing shielding failure, achieving the optimal balance between cost and performance.
[0039] S2: The first retaining wall 4 and the second retaining wall 5 are designed to form a misaligned area 7 in the horizontal direction and an overlapping area 8 in the vertical direction, so that an electromagnetic shielding channel is formed between the first retaining wall 4 and the second retaining wall 5. Designers need to optimize the height, thickness and overlap of the first retaining wall 4 and the second retaining wall 5 based on the process constraints such as the draft angle, minimum wall thickness and fillet radius of the die-casting mold. The manufacturing process capabilities are directly input into the design model, thereby shortening the development cycle and reducing the number of mold trials.
[0040] S3: Design the structure of the metal shielding spring 6 so that the metal shielding spring 6 simultaneously abuts against the first barrier wall 4 and the second barrier wall 5 in a conductive overlapping manner. The warpage angle, height, and density of fin 9 need to be analyzed to ensure that no plastic deformation occurs under maximum compression; the contact pressure needs to meet the minimum membrane breakdown pressure requirement in electrical contact theory, while being lower than the material fatigue limit.
[0041] S4: Multiple contact points with the second retaining wall 5 are provided on the metal shielding spring 6, and multiple slots for engaging the first retaining wall 4 are provided below the metal shielding spring 6; The opening size of the U-shaped slot 10 needs to match the cutting edge strength of the stamping die to ensure the feasibility of mass production of the metal shielding spring 6.
[0042] S5: The metal shielding spring 6 is pre-installed on the first retaining wall 4. After the motor housing 1 and the electrical control housing 2 are assembled, they are fastened with bolts so that the metal shielding spring 6, the first retaining wall 4 and the second retaining wall 5 are simultaneously electrically connected to form a dynamic electrical connection path.
[0043] During pre-assembly, the metal shielding spring 6 establishes an electrical connection with the first retaining wall 4; during the closing process, the second retaining wall 5 compresses the fins 9 to produce elastic deformation, and the contact resistance decreases as the pressure increases; after the bolts are tightened, a stable conductive path is formed between the motor housing 1 and the electrical control housing 2 through the metal shielding spring 6. The closing action itself is used as the assembly driving force of the shielding structure, without the need for additional procedures. At the same time, the bolt torque after closing can indirectly control the compression amount of the metal shielding spring 6.
[0044] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.
Claims
1. An integrated hybrid transmission three-phase EMC shielding structure, comprising a motor housing and an electronic control housing, characterized in that, Further included are: A three-phase through-tank connector that passes through the junction of the motor housing and the electronic control housing, and a first retaining wall and a second retaining wall are respectively provided between the three-phase through-tank connector and the motor housing and the electronic control housing; Wherein, the first retaining wall and the second retaining wall have a misalignment area in the horizontal direction, and the first retaining wall and the second retaining wall have an overlapping area in the vertical direction, and an electromagnetic shielding channel is formed between the misalignment area and the overlapping area; A metal shielding shrapnel, which is arranged between the first retaining wall and the second retaining wall, and the metal shielding shrapnel abuts against the first retaining wall and the second retaining wall in a conductive lap joint manner; Wherein, the metal shielding shrapnel, the first retaining wall and the second retaining wall form a dynamic electrical connection path between the motor housing and the electronic control housing.
2. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that: The first retaining wall and the second retaining wall are in a "return" shaped closed structure, the assembly gap of the misalignment area is 2 mm - 3 mm, and the length of the overlapping area is greater than or equal to 5 mm.
3. The integrated hybrid transmission three-phase EMC shielding structure according to claim 2, characterized in that: The thickness of both the first retaining wall and the second retaining wall is 2.0 mm - 2.5 mm, and the gap between the first retaining wall and the second retaining wall in the vertical direction is 1.9 mm - 2.1 mm.
4. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that: The metal shielding shrapnel is in a "return" shaped closed structure, and the "return" shaped structure of the metal shielding shrapnel is adapted to the "return" shaped structures of the first retaining wall and the second retaining wall. The overall thickness of the metal shielding shrapnel is 0.3 mm - 0.5 mm, and the width is 3.4 mm - 3.6 mm.
5. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that: A plurality of upwardly翘起fins are provided on the metal shielding shrapnel. The fins are spaced apart in the vertical direction, and multiple-point contact is formed between the fins and the second retaining wall.
6. The integrated hybrid transmission three-phase EMC shielding structure according to claim 5, characterized in that: The length of the fin is 6.7 mm - 6.9 mm, the width of the fin is 1.3 mm - 1.5 mm, the spacing between adjacent fins is 8.4 mm - 8.6 mm, the number of fins is 30 - 32, and the free height of the fin is 30% - 50%.
7. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that: A plurality of U-shaped card slots are provided below the metal shielding shrapnel. One side of the U-shaped card slot has an outward turning guiding angle, and the angle of the outward turning guiding angle is 30° - 45°. The metal shielding shrapnel is snap-fitted to the first retaining wall through the U-shaped card slot, and the unilateral fitting gap between the U-shaped card slot and the first retaining wall is 0.4 mm - 0.5 mm.
8. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that: The metal shielding shrapnel adopts a planar or staggered structure to adapt to the first retaining wall and the second retaining wall with different heights.
9. The integrated hybrid transmission three-phase EMC shielding structure according to claim 1, characterized in that, The contact between the metal shielding shrapnel and the first retaining wall and the second retaining wall forms a parallel low-inductance grounding path of "motor housing - metal shielding shrapnel - electronic control housing".
10. A design method for an integrated hybrid transmission three-phase EMC shielding, comprising the integrated hybrid transmission three-phase EMC shielding structure as described in any one of claims 1-9, characterized in that, It includes the following steps: S1: According to the installation position of the three-phase through-tank connector at the junction of the motor housing and the electronic control housing, determine the arrangement areas of the first retaining wall and the second retaining wall; S2: Design the first retaining wall and the second retaining wall to form a misalignment area in the horizontal direction and an overlapping area in the vertical direction, so that an electromagnetic shielding channel is formed between the first retaining wall and the second retaining wall; S3: Design the structure of the metal shielding shrapnel so that the metal shielding shrapnel abuts against the first retaining wall and the second retaining wall simultaneously in a conductive lap joint manner; It should be noted that the word "翘起" in the original text seems to be incorrect or incomplete. I translated it as "翘起" for now. You may need to check and correct it if necessary. S4: Multiple contact points with the second retaining wall are set on the metal shielding spring, and multiple slots for engaging the first retaining wall are set below the metal shielding spring; S5: The metal shielding spring is pre-installed on the first retaining wall. After the motor housing and the electrical control housing are assembled, they are fastened with bolts so that the metal shielding spring is simultaneously conductively connected to the first and second retaining walls, forming a dynamic electrical connection path.