Wireless charging coil module with magnetic core without surrounding edge

Abstract

The invention relates to the technical field of wireless charging, and discloses a wireless charging coil module with a magnetic core without a surrounding edge, which comprises a bracket and an electromagnetic coil, the electromagnetic coil is coaxially assembled on the bracket, and a planar manganese zinc ferrite magnetic core which is used for fixing the electromagnetic coil and is provided with a non-circumferential annular limiting surrounding edge is assembled between the electromagnetic coil and the bracket. A cylindrical limiting boss for limiting the displacement of the electromagnetic coil is fixedly arranged on the top end surface of the magnetic core, and the electromagnetic coil is formed by coiling a plurality of strands of enameled wires; according to the wireless charging coil module, the problem that CNC cutting machining procedures must be executed in the prior art is effectively solved, and the production and machining threshold and the comprehensive manufacturing cost of the wireless charging coil module are greatly reduced; various performance defects caused by weakening of the radial constraint capacity of the magnetic path after the peripheral annular limiting surrounding edge of the magnetic core is removed are effectively overcome, and it is guaranteed that the charging transmission efficiency and the core working performance of the module are not lower than those of an existing product of the same specification with a surrounding edge structure.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology, specifically to a wireless charging coil module with a magnetic core without surrounding edges. Background Technology

[0002] With the rapid development of wireless charging technology, magnetic wireless charging has been widely used in smartphones, wearable devices, automotive electronics, smart homes, and many other fields due to its advantages of precise positioning, high coupling efficiency, and ease of use. The wireless charging coil module is the core component of magnetic charging devices, enabling energy conversion and transmission. It mainly includes a bracket, electromagnetic coil, ferrite core, magnetic structure, temperature control components, and shielding structure. The ferrite core's core function is to provide a low-resistivity conduction path for the alternating magnetic field generated by the electromagnetic coil, constraining leakage flux, improving electromagnetic coupling efficiency, and isolating electromagnetic interference. It is a key component determining charging performance and product reliability.

[0003] In existing magnetic wireless charging coil module designs, to ensure the coaxial mounting accuracy of the electromagnetic coil and ferrite core, and to avoid issues such as decreased coupling efficiency and increased heat generation due to misalignment or skew during coil assembly, the commonly used technical solution in the industry is to integrally machine a closed-loop annular limiting edge on the upper surface of the ferrite core. This limiting edge forms an annular limiting groove that matches the outer diameter of the electromagnetic coil. During assembly, the electromagnetic coil is directly inserted into the limiting groove, achieving omnidirectional limiting and coaxial positioning of the coil. However, in actual production and application, the ferrite core structure with the limiting edge suffers from high processing costs and extremely low mass production efficiency. Because this type of ferrite core with a circumferential limiting edge is an irregular structure, it cannot be formed in one piece by stamping and must be completed by CNC machining. This not only involves multiple processing steps, long production cycles, and significant material waste, but also results in high unit processing costs and large equipment investment, making it unsuitable for the large-scale, low-cost mass production requirements of the consumer electronics field. Summary of the Invention

[0004] (I) Technical problem to be solved: In view of the shortcomings of the existing technology, the present invention provides a wireless charging coil module with a magnetic core without a surrounding edge, which can be stamped and formed in one piece, and has the advantages of low cost, high mass production efficiency and low material loss. It solves the problems of existing ferrite magnetic cores having irregular structure, requiring CNC cutting and machining, resulting in high cost, low mass production efficiency and high material loss.

[0005] (II) Technical Solution: To achieve the above-mentioned one-time stamping molding with low cost, high mass production efficiency and low material loss, the present invention provides the following technical solution: A wireless charging coil module with a magnetic core without a perimeter, including a bracket and an electromagnetic coil that generates a changing magnetic field to charge the device. The electromagnetic coil is coaxially mounted on the bracket. A planar manganese-zinc ferrite magnetic core without a perimeter ring limiting perimeter is mounted between the electromagnetic coil and the bracket to fix the electromagnetic coil. A cylindrical limiting boss is fixedly provided on the top surface of the magnetic core to limit the displacement of the electromagnetic coil. The electromagnetic coil is formed by winding multiple strands of enameled wire. The outer diameter of the limiting boss is adapted to the inner diameter of the electromagnetic coil.

[0006] Preferably, under the same rated charging power conditions, the number of coiled strands of the electromagnetic coil mounted on a planar magnetic core without a perimeter ring-shaped limiting edge is greater than the number of coiled strands of the electromagnetic coil mounted on a magnetic core of the same specification with a perimeter ring-shaped limiting edge. The increased number of coiled strands of the electromagnetic coil compensates for the performance loss of the magnetic core without a perimeter ring structure.

[0007] Preferably, the magnetic core is coaxially assembled with the electromagnetic coil, and the limiting boss is coaxially fixed with the magnetic core.

[0008] Preferably, the diameter of the magnetic core is larger than the diameter of the electromagnetic coil.

[0009] Preferably, the limiting boss and the magnetic core adopt an integrated structure.

[0010] Preferably, the limiting boss and the magnetic core are separate independent components, and the bottom of the limiting boss is fixedly connected to the top surface of the magnetic core through a cured adhesive layer.

[0011] Preferably, an aluminum base with a diameter larger than that of the magnetic core is fixedly assembled between the magnetic core and the bracket. The magnetic core and the aluminum base are also machined with wire grooves, which contain connecting wires connected to the electromagnetic coil. The bracket is also machined with a wire harness groove that matches the wire groove, and the connecting wire passes through the wire harness groove to connect to an external control circuit.

[0012] Preferably, the top surface of the limiting boss is higher than the top surface of the electromagnetic coil.

[0013] Preferably, an annular magnet array is also fixedly mounted on the aluminum base, the inner diameter of the magnet array being larger than the outer diameter of the magnetic core.

[0014] Preferably, the bracket has three or more sets of legs machined at equal intervals along its circumference.

[0015] Preferably, a shielding coil with a diameter larger than that of the electromagnetic coil is coaxially fixed on the magnetic core. The shielding coil generates a reverse magnetic field to counteract the magnetic force leaked by the electromagnetic coil. The current flowing through the shielding coil is opposite to that of the electromagnetic coil, and shielding wires are connected to both ends of the shielding coil. The shielding wires pass through the wire harness slot and are connected to the external control circuit.

[0016] Preferably, the number of strands of the shielding coil is one or more.

[0017] (III) Beneficial Effects: Compared with the prior art, the present invention provides a wireless charging coil module with a magnetic core without a surrounding edge, which has the following beneficial effects: 1. This wireless charging coil module without a magnetic core effectively solves the problem of CNC machining, which must be performed in the existing technology, by using the magnetic core structure and the electromagnetic coil structure in combination. This significantly reduces the production threshold and overall manufacturing cost of the wireless charging coil module. Furthermore, by increasing the number of coiled strands of the electromagnetic coil, it effectively compensates for the performance defects caused by the weakening of the magnetic path constraint after removing the circumferential ring-shaped limiting edge of the magnetic core. This ensures that the charging transmission efficiency and core working performance of the module are no less than those of existing products of the same specifications with a ring-shaped edge structure. This achieves a significant reduction in production and manufacturing costs while ensuring the stability of core working performance.

[0018] 2. This wireless charging coil module with a magnetic core without a surrounding edge is designed in two ways: an integrated structure and a separate structure. The integrated stamped limiting boss utilizes the forming advantage of symmetrical solid protrusions to adapt to large-scale standardized mass production. The separate bonded limiting boss achieves modularization of the magnetic core function, and the magnetic core body can be mass-produced in a universal manner. The limiting boss has high selectivity in material and specifications, and can adapt to the needs of multi-specification small-batch customization.

[0019] 3. This wireless charging coil module without a perimeter of the magnetic core solves the technical problems of increased stray magnetic leakage and deteriorated electromagnetic shielding caused by the weakening of magnetic path constraint after removing the perimeter of the magnetic core by coaxially setting a shielding coil on a planar magnetic core without a perimeter ring-shaped limiting edge. By actively generating a reverse alternating magnetic field, the module achieves vector cancellation of radially scattered leakage magnetic field of the electromagnetic coil from the source of magnetic field generation, greatly reducing the outward radiated stray magnetic field and avoiding electromagnetic interference to surrounding electronic devices during module operation. At the same time, the shielding coil is set in the outer radial region of the electromagnetic coil, and the reverse magnetic field it generates only acts on the spatial range of leakage magnetic radiation, without interfering with the main coupling magnetic field between the electromagnetic coil and the receiving coil. While achieving leakage magnetic suppression, it does not negatively affect the energy transmission efficiency of wireless charging. It can form a synergistic effect with the performance compensation scheme of increasing the number of coil strands in the electromagnetic coil in this application, and make up for the performance loss caused by the perimeterless magnetic core structure. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural schematic diagram of the wireless charging coil module with no surrounding magnetic core in this invention. Figure 2 This is a front view of the structure of the wireless charging coil module with no surrounding magnetic core in this invention; Figure 3 This is a top view of the structure of the wireless charging coil module with no surrounding magnetic core in this invention; Figure 4 This is a top view of the structure of the wireless charging coil module with no surrounding magnetic core in this invention; Figure 5 This is a cross-sectional view of the structure of the wireless charging coil module with no surrounding magnetic core in this invention; Figure 6 This is an exploded view of the structure of the wireless charging coil module with no surrounding magnetic core in this invention; Figure 7 This is an exploded view of the structure in Example 2; Figure 8 This is a top view of the structure in Embodiment 3; Figure 9 This is a cross-sectional view of the structure in Example 3.

[0021] In the diagram: 1. Bracket; 11. Support leg; 12. Cable tray; 2. Electromagnetic coil; 21. Connecting wire; 3. Aluminum base; 31. Magnet array; 4. Magnetic core; 41. Limiting boss; 5. Wire tray; 6. Shielded coil; 61. Shielded wire. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 Please see Figures 1-6A wireless charging coil module with a magnetic core 4 without a perimeter ring includes a bracket 1 and an electromagnetic coil 2 that generates a changing magnetic field to charge the device. The electromagnetic coil 2 is coaxially mounted on the bracket 1. A planar manganese-zinc ferrite magnetic core 4 without a perimeter ring limiting perimeter is mounted between the electromagnetic coil 2 and the bracket 1 to fix the electromagnetic coil 2. A cylindrical limiting boss 41 is fixedly provided on the top surface of the magnetic core 4 to limit the displacement of the electromagnetic coil 2. The top surface of the magnetic core 4 faces the bottom surface of the electromagnetic coil 2 and is in close contact with the electromagnetic coil 2. A cylindrical limiting boss 41 is provided at the center of the top surface of the magnetic core 4. The limiting boss 41 extends towards the inner circle of the electromagnetic coil 2 to form a radial limit on the electromagnetic coil 2. The reason for adopting the planar magnetic core 4 structure without a perimeter ring limiting perimeter is to completely eliminate the need for CNC machining of the existing irregularly shaped magnetic core 4 with a perimeter ring. Due to technological limitations, the magnetic core 4 can be formed in one piece using standardized molds, significantly simplifying the processing steps, reducing manufacturing costs, and shortening the production cycle, thus meeting the needs of large-scale mass production. The choice of manganese-zinc ferrite material is due to its excellent soft magnetic properties of high permeability and low magnetic reluctance within the wireless charging operating frequency band. This provides a low-loss conduction path for the alternating magnetic field generated by the electromagnetic coil 2, effectively constraining leakage flux and improving electromagnetic coupling efficiency. The cylindrical limiting boss 41 is designed so that this symmetrical solid protrusion structure can form a stable fit and limit with the inner ring of the electromagnetic coil 2, while also possessing excellent stamping processability, avoiding the problems of easy cracking and damage that occur when stamping thin-walled edge structures. While simplifying the processing of the magnetic core 4, it fully realizes the installation and positioning function of the electromagnetic coil 2, avoiding various performance defects caused by coil assembly misalignment. The electromagnetic coil 2 is formed by winding multiple strands of enameled wire, and the outer diameter of the limiting boss 41 matches the inner diameter of the electromagnetic coil 2. The electromagnetic coil 2 is made of multiple strands of enameled wire with a high-temperature resistant insulating varnish film on the surface, tightly wound and formed in a single-layer flat disc shape. The inner circle of the completed electromagnetic coil 2 forms a circular hollow cavity. The outer diameter of the limiting boss 41 is adapted to the inner diameter of the electromagnetic coil 2, so that the inner wall of the inner circle of the electromagnetic coil 2 can fit and limit the movement with the outer wall of the limiting boss 41. After the electromagnetic coil 2 is pre-positioned by fitting its inner circle onto the outer wall of the limiting boss 41, its bottom surface is fixedly bonded to the top surface of the magnetic core 4 with high-temperature resistant insulating double-sided adhesive.

[0024] Please see Figures 1-6Since the magnetic core 4 loses the constraint effect of the outer ring high permeability structure on the radially scattered alternating magnetic field after the removal of the peripheral ring limiting edge, problems such as increased leakage magnetic field, decreased magnetic flux coupling strength between the transmitting and receiving coils, increased power transmission loss, and weakened electromagnetic shielding effect will occur. Therefore, under the same rated charging power conditions, the number of coils of electromagnetic coil 2 mounted on the planar magnetic core 4 without the peripheral ring limiting edge is greater than the number of coils of electromagnetic coil 2 mounted on the same specification magnetic core 4 with the peripheral ring limiting edge. The increased number of coils of electromagnetic coil 2 compensates for the performance loss of the magnetic core 4 without the edge structure. By increasing the number of coil strands in the electromagnetic coil 2, the high-frequency AC impedance of the coil can be further reduced, the magnetic flux density of the electromagnetic coil 2 can be increased, the magnetic field strength of the charging coupling working area can be strengthened, and more magnetic lines of force can be concentrated and constrained in the effective coupling area. This can compensate for the magnetic flux loss caused by the weakening of the magnetic path constraint capability, offset the problem of reduced charging transmission efficiency caused by increased leakage flux, and suppress the outward radiation of electromagnetic interference. This ensures that the charging transmission efficiency, electromagnetic compatibility performance and working stability of the coil module without a perimeter structure are no less than those of the same specification coil module with a perimeter ring-shaped limiting perimeter magnetic core 4. By increasing the number of strands in electromagnetic coil 2 to 10, from the original 65 strands to 75 strands, the performance loss caused by removing the edging is compensated. The 10 additional strands in electromagnetic coil 2 can greatly reduce the DC resistance and the AC equivalent series resistance under high-frequency alternating current, effectively suppressing the additional losses caused by the high-frequency skin effect and proximity effect. At the same time, under the same driving current conditions, electromagnetic coil 2 with an increased number of strands can generate a higher working magnetic field flux density, re-concentrating and confining more of the originally radially scattered magnetic lines of force within the effective coupling area between the transmitter and receiver, compensating for the loss of effective coupling flux caused by the weakening of the magnetic path constraint capability after removing the edging of magnetic core 4, and offsetting the decrease in charging transmission efficiency caused by the increase in leakage flux.

[0025] Please see Figures 1-6In the core 4 processing and forming stage, this application adopts a planar regular structure ferrite core 4 without a peripheral annular limiting edge. This planar regular structure ferrite core 4 does not require additional CNC cutting processing during processing, fundamentally solving the industry pain points of existing ferrite cores 4 with peripheral annular limiting edges, such as cumbersome processing steps, large raw material loss, long production cycle, low mass production efficiency, and high manufacturing cost.In the prior art, the ferrite core 4 with a surrounding annular limiting edge is an irregular, irregular structure. Due to the inherent material properties of ferrite, such a structure cannot be formed in one stamping process using standardized molds. It must be milled piece by piece using high-precision CNC machining. This machining method not only requires investment in high-precision machining equipment and customized tooling fixtures, but also suffers from inherent defects such as multiple machining steps, long production process, high raw material loss rate, and extremely low effective capacity per unit time of a single machine. This results in high processing cost and long production cycle for a single core 4. In contrast, the present application adopts a method that increases the number of strands of the electromagnetic coil 2. The performance compensation technology eliminates the need for machining a circumferential ring-shaped limiting edge on the magnetic core 4, thus reducing machining time and costs. It compensates for the increased magnetic flux leakage and decreased magnetic flux coupling strength between the transmitting and receiving coils caused by the weakened magnetic path constraint without the ring-shaped limiting edge by increasing the number of coils wound on the electromagnetic coil 2. This counteracts the increased charging power transmission loss and decreased energy transmission efficiency resulting from the lack of a ring-shaped limiting edge. In actual production, only the winding program of the existing fully automatic coil winding equipment needs to be adjusted to increase the number of turns of the electromagnetic coil 2 on the limiting boss 41. The magnetic core 4 only requires machining one limiting boss 41, eliminating the need for additional machining. The CNC machining process eliminates the need for additional production equipment, customized tooling, and core production steps. It only generates a small increase in enameled wire raw materials, and the production cycle of a single electromagnetic coil 2 remains almost unchanged. This significantly shortens the overall production cycle of the wireless charging coil module and greatly reduces manufacturing costs. Furthermore, by increasing the number of parallel strands in the electromagnetic coil 2, the high-frequency AC impedance of the electromagnetic coil 2 under high-frequency operating conditions in wireless charging technology can be greatly reduced, effectively suppressing the skin effect under high-frequency alternating current. This significantly improves the quality factor (Q value) and electromagnetic energy conversion efficiency of the electromagnetic coil 2, and also increases efficiency under the same driving current conditions. The magnetic flux density of the working magnetic field of the electromagnetic coil 2 is increased, and the magnetic field strength of the charging coupling working area is strengthened. This compensates for the magnetic flux loss caused by the weakening of the magnetic path constraint ability after the removal of the ferrite core 4 with the peripheral ring limiting edge. As a result, more magnetic lines of force are concentrated and constrained in the effective charging coupling area, which offsets the problem of decreased charging transmission efficiency caused by the increase in leakage magnetic field due to the absence of the edge. This ensures that the charging transmission efficiency of the wireless charging coil module in this application is not lower than that of the coil module of the same specification with the peripheral ring limiting edge magnetic core 4. Ultimately, this significantly reduces the manufacturing cost of the wireless charging coil module, shortens the production cycle, and improves mass production efficiency, while ensuring the core working performance of the wireless charging coil module.

[0026] Please see Figures 1-6The magnetic core 4 and the electromagnetic coil 2 are coaxially assembled, and the limiting boss 41 is coaxially fixed with the magnetic core 4. The diameter of the magnetic core 4 is larger than the diameter of the electromagnetic coil 2. This ensures that the central axes of the magnetic core 4, the limiting boss 41, and the electromagnetic coil 2 are completely coincident, allowing the alternating magnetic field generated by the electromagnetic coil 2 to be evenly distributed along the central axis and completely received and constrained by the magnetic core 4. The design that the diameter of the magnetic core 4 is larger than the diameter of the electromagnetic coil 2 allows the effective magnetic circuit working surface of the magnetic core 4 to completely cover the entire winding area of ​​the electromagnetic coil 2, providing a complete and continuous low magnetic reluctance conduction path for all the alternating magnetic fields generated by the coil. This avoids the problem of a significant increase in leakage magnetic field due to the magnetic field in the edge area of ​​the coil not being effectively constrained by the magnetic core 4. At the same time, it can provide a complete support and contact surface for the bottom of the coil, improve the heat conduction efficiency between the coil and the magnetic core 4, accelerate the diffusion of heat from the coil, and reduce the operating temperature rise of the coil. The limiting boss 41 and the magnetic core 4 adopt an integrated structure. The magnetic core 4 body and the limiting boss 41 are pressed and formed simultaneously by a set of stamping dies, eliminating the need for subsequent separate assembly and bonding processes, which greatly simplifies the production process and improves production efficiency.

[0027] Please see Figures 1-6In the process of processing the magnetic core 4, the limiting boss 41 on the magnetic core 4 is integrally formed by stamping. Since the cylindrical limiting boss 41 located at the center of the top surface of the magnetic core 4 is a solid protrusion structure that is completely coaxially symmetrical with the body of the magnetic core 4, it does not have the thin-walled closed-loop irregular shape characteristic of the outer ring limiting edge. During the molding process, the mold cavity can be designed with complete symmetry, which can ensure the uniform filling of ferrite powder in the mold cavity. During the pressing process, the pressing force on the magnetic core 4 body area and the limiting boss 41 area is completely uniform and consistent, and there will be no problem of local stress concentration. During the demolding process, the separation of the limiting boss 41 structure from the mold cavity is a demolding without lateral stress along the vertical axis, which completely avoids the defects of cracking, damage, and fracture that are easily caused by lateral shear stress on the thin-walled structure of the outer ring limiting edge during demolding. During the machining of the limiting boss 41, firstly, based on the design dimensions of the planar magnetic core 4 without a circumferential annular limiting edge and the central cylindrical limiting boss 41, an integrated stamping die is machined. The die cavity simultaneously integrates the planar forming cavity of the magnetic core 4 body and the protruding forming cavity of the limiting boss 41. Subsequently, manganese-zinc ferrite powder prepared according to the formula ratio is evenly filled into the cavity of the stamping die through a fully automatic feeding mechanism. A preset rated pressure is applied by a hydraulic press to press the ferrite powder in the cavity under constant pressure, so that the powder is integrally formed in the closed die cavity. The planar magnetic core 4 blank, equipped with a central coaxial limiting boss 41, is demolded along the vertical axis by the ejection mechanism of the mold after pressure holding. The demolded blank is then placed in a high-temperature sintering furnace and sintered according to the preset sintering temperature curve of the manganese-zinc ferrite material. This process densifies the blank and stabilizes its magnetic properties. After sintering, only simple surface cleaning, dimensional accuracy checks, and magnetic performance inspections are required to obtain the finished magnetic core 4. The entire process requires no additional CNC machining, significantly reducing processing costs and time. Furthermore, a multi-cavity mold design allows for the simultaneous pressing of multiple magnetic core 4 products. Combined with fully automated feeding, pressing, and demolding equipment, fully automated continuous production is achieved, greatly improving the mass production efficiency of the magnetic core 4. Moreover, the absence of raw material cutting loss during pressing significantly reduces the manufacturing cost of the magnetic core 4.

[0028] Please see Figures 1-6An aluminum base 3 with a diameter larger than that of the magnetic core 4 is fixedly assembled between the magnetic core 4 and the support 1. A wire groove 5 is machined on both the magnetic core 4 and the aluminum base 3, and the wire groove 5 contains a connecting wire 21 connected to the electromagnetic coil 2. The aluminum base 3, made of pure aluminum or aluminum alloy with a high thermal conductivity, is integrally stamped. The bottom surface of the aluminum base 3 is fixedly bonded to the mounting reference surface of the support 1 using high-temperature resistant insulating double-sided adhesive, and the top surface of the aluminum base 3 is fixedly bonded to the mounting reference surface of the support 1 using high thermal conductivity insulating adhesive. Double-sided adhesive is used to fix and bond the wire to the bottom surface of the magnetic core 4. The wire groove 5 extends radially along the magnetic core 4 and the aluminum base 3. The width and depth of the wire groove 5 are greater than the outer diameter of the connecting wire 21, so that the connecting wire 21 can be completely accommodated inside the wire groove 5. A wire harness groove 12 that matches the wire groove 5 is also machined on the bracket 1. The cooperation between the wire groove 5 and the wire harness groove 12 can provide a regular layout path and protective space for the connecting wire 21, avoiding problems such as pulling, bending, and squeezing damage to the connecting wire 21 during assembly and use, and ensuring the stability of electrical signal transmission. The connecting wire 21 passes through the wire harness groove 12 and connects to the external control circuit. The control circuit specifically includes a rectifier filter circuit, a power factor correction circuit, a high-frequency inverter circuit, a resonant compensation circuit, an MCU main control circuit, a temperature protection circuit, and an overcurrent and overvoltage protection circuit.

[0029] Please see Figures 1-6The top surface of the limiting boss 41 is higher than the top surface of the electromagnetic coil 2, which allows the limiting boss 41 to fully enclose and limit the inner ring of the electromagnetic coil 2 in the axial direction, thus preventing axial tilting and radial displacement of the coil during assembly and use. A ring-shaped magnet array 31 is also fixedly installed on the aluminum base 3, and the inner diameter of the magnet array 31 is larger than the outer diameter of the magnetic core 4. The magnet array 31 uses multiple permanent magnets arranged equidistantly along the circumference to form a closed-loop annular structure. The permanent magnets are fixedly bonded to the top surface of the aluminum base 3 with high-temperature resistant foam adhesive. The central axis of the magnet array 31 is completely coincident with the central axis of the magnetic core 4. The inner diameter of the magnet array 31 is larger than the outer diameter of the magnetic core 4, so that the magnet array 31 is arranged around the outer ring of the magnetic core 4, with a uniform annular gap reserved between them. The annular magnet array 31 can generate a stable magnetic field, forming a precise magnetic alignment with the magnetic attraction structure in the device to be charged. This guides the receiving coil of the device to be charged to be precisely coaxially aligned with the electromagnetic coil 2 of this module, avoiding the problem of reduced charging efficiency due to alignment deviation. Setting the inner diameter of the magnet array 31 to be larger than the outer diameter of the magnetic core 4 allows the magnet array 31 to completely avoid the effective magnetic circuit working area of ​​the magnetic core 4, preventing the magnetic field of the magnet array 31 from interfering with the alternating magnetic field constrained by the magnetic core 4. The bracket 1 has three or more sets of legs 11 machined at equal intervals along its circumference. The legs 11 and the bracket 1 body are integrally injection molded from the same material. The legs 11 extend outward along the radial direction of the bracket 1. The legs 11 can provide multiple points of uniform support and fixation for the bracket 1.

[0030] Example 2 Please see Figure 7 The limiting boss 41 and the magnetic core 4 are separate independent components. The bottom of the limiting boss 41 is fixedly connected to the top surface of the magnetic core 4 through a cured adhesive layer. The adhesive layer is made of high-temperature resistant epoxy structural adhesive, which has the characteristics of high bonding strength, high resistance to high and low temperature impact, high insulation and low shrinkage. Its long-term operating temperature can cover the conventional operating temperature range of wireless charging coil modules. The cured adhesive layer has excellent shear strength and peel strength, as well as good aging resistance and damp heat resistance.

[0031] Please see Figure 7During the processing of the magnetic core 4, the limiting boss 41 is a separate independent component from the limiting magnetic core 4. The bottom of the limiting boss 41 is fixedly connected to the top surface of the magnetic core 4 through a cured adhesive layer. This means that the magnetic core 4 does not need to undergo additional stamping processing during processing. After the magnetic core 4 is processed, a set of limiting bosses 41 can be coaxially fixed through the adhesive layer, which is more suitable for small-batch production. The processing begins with the machining of the magnetic core 4 body without a circumferential ring-shaped limiting edge. Then, the separate cylindrical limiting boss 41 is machined independently. The separate limiting boss 41 can be flexibly made of manganese-zinc ferrite, high-strength engineering plastic, or high-hardness alumina ceramic material, depending on the product's positioning requirements, magnetic circuit design, and cost control objectives. If manganese-zinc ferrite is used, it is pressed and sintered at high temperature using a small precision stamping die. If a non-metallic material is used, it is prepared through precision injection molding or micro-machining. After machining, the outer diameter, coaxiality, and flatness of the limiting boss 41 are fully inspected to select finished products that meet the tolerance requirements for matching the inner diameter of the electromagnetic coil 2. Then, through a coaxial bonding and fixing process, the planar magnetic core 4 body and the separate limiting boss 41 are pre-aligned using a coaxial positioning fixture. Finally, the limiting boss 41 is fixed by bonding. The bottom surface of the core 4 is uniformly coated with a pre-set thickness of high-temperature resistant epoxy structural adhesive or acrylic structural adhesive. The pre-aligned limiting boss 41 is then vertically pressed onto the center of the top surface of the core 4 body at a pre-set position with constant pressure. At the same time, the amount of adhesive applied and the pressing pressure are controlled to avoid the problem of adhesive overflow and contamination of the effective magnetic circuit working surface of the core 4 during the adhesive application process. Subsequently, the pressed core 4 assembly is placed in a constant temperature curing oven and cured under constant temperature and pressure according to the curing process parameters of the selected structural adhesive. This allows the structural adhesive to complete a full cross-linking reaction, forming an adhesive layer and achieving rigid fixation between the limiting boss 41 and the core 4 body. In this processing flow, the core 4 body can be prepared in advance on a large scale and in a standardized manner. Only the processing and bonding of the corresponding specification limiting boss 41 need to be completed according to the order requirements. No additional mold opening investment and long cycle processing are required. It is especially suitable for the production needs of customized products with multiple specifications and small batches.

[0032] Example 3 Please see Figure 8 and Figure 9A shielding coil 6, with a diameter larger than that of the electromagnetic coil 2, is coaxially fixed on the magnetic core 4. The shielding coil 6 generates a reverse magnetic field to counteract the magnetic force leaking from the electromagnetic coil 2. The current flowing through the shielding coil 6 is opposite to that of the electromagnetic coil 2. The shielding coil 6 is made of enameled wire with a surface coated with a high-temperature insulating varnish, coiled into a flat, closed-loop annular structure that matches the shape of the magnetic core 4. The central axis of the shielding coil 6 is completely coincident with the central axis of the magnetic core 4 and the central axis of the electromagnetic coil 2. The inner diameter of the shielding coil 6 is larger than the outer diameter of the electromagnetic coil 2, so that the shielding coil 6 is arranged around the outer radial region of the electromagnetic coil 2, with a uniform annular insulating gap reserved between them. The bottom surface of the shielding coil 6 is fixedly bonded to the top surface of the magnetic core 4 with high-temperature insulating double-sided adhesive. The winding plane of the shielding coil 6 is in the same horizontal plane as the winding plane of the electromagnetic coil 2. Shielding wires 61 are connected to both ends of the shielding coil 6. The shielding wires 61 pass through the wire harness groove 12 and are connected to an external control circuit. The control circuit connected to the shielding wires 61 is different from that connected to the connecting wires 21. The two output terminals of the shielded coil 6 are respectively connected to the shielded wire 61. The shielded wire 61 is a multi-strand stranded insulated wire with high temperature resistance, high insulation, and high flexibility. The shielded wire 61 can be connected to an independent shielded coil 6 drive unit in the external control circuit, or it can be directly connected to the existing external control circuit identical to that of the electromagnetic coil 2. When an independent shielded coil 6 drive unit is used, the control circuit unit connected to the shielded wire 61 and the connecting wire 21 is completely independent. This independent circuit connection design enables completely independent control of the shielded coil 6 and the electromagnetic coil 2, avoiding mutual interference between the drive circuits of the two coils. When the shielded coil 6 is powered by the same external control circuit as the electromagnetic coil 2, a parallel circuit topology with the same source and reverse connection is used for the overall design. The connecting wire 21 of the electromagnetic coil 2 and the shielded wire 61 of the shielded coil 6 are connected in parallel to the same external control circuit power supply through reverse wiring. The high-frequency alternating output terminal aligns the current input terminal of the electromagnetic coil 2 with the current output terminal of the shielding coil 6, and the current output terminal of the electromagnetic coil 2 with the current input terminal of the shielding coil 6. This ensures that the external control circuit power supply outputs high-frequency alternating currents with completely consistent frequency and completely opposite phase to the electromagnetic coil 2 and the shielding coil 6 synchronously. This satisfies the core working requirement of the shielding coil 6 generating a reverse magnetic field to cancel the leakage flux of the electromagnetic coil 2. At the same time, the electrical parameters of the shielding coil 6, such as wire diameter, number of coils, and inductance, are designed to be compatible with the electrical parameters of the electromagnetic coil 2. This allows the shielding coil 6 to generate a reverse alternating magnetic field in the same power supply circuit that is compatible with the magnetic field amplitude of the radially scattered leakage flux of the electromagnetic coil 2. This avoids the problem of the reverse magnetic field being too strong and interfering with the main coupling magnetic field, or the reverse magnetic field being insufficient and causing the leakage flux suppression effect to be substandard. Furthermore, when the same external control circuit is used for power supply, no additional external equipment is required, which can greatly reduce the equipment cost.The shielding coil 6 has one or more strands, and the number of strands can be flexibly adjusted according to the module's leakage flux suppression requirements, installation space limitations, and cost control objectives. When a single strand of enameled wire is used for winding, it can be adapted to lightweight product scenarios with compact installation space and moderate leakage flux suppression requirements. When multiple strands of enameled wire are used for parallel winding, it can effectively reduce the AC impedance of the shielding coil 6 in high-frequency operating scenarios, improve the generation efficiency and stability of the reverse magnetic field, and adapt to product scenarios with high charging power and high leakage flux suppression requirements.

[0033] Please see Figure 8 and Figure 9 Because the electromagnetic coil 2 generates a main alternating magnetic field for wireless charging energy transmission after a high-frequency alternating charging current is applied, and due to the weakened magnetic path constraint capability after the removal of the peripheral annular limiting edge of the magnetic core 4, a large number of magnetic lines of force in the main alternating magnetic field will detach from the effective charging coupling area and scatter outward radially along the outer ring of the electromagnetic coil 2, forming stray leakage magnetic field. This leakage magnetic field not only reduces the electromagnetic coupling efficiency between the electromagnetic coil 2 and the receiving coil and increases energy transmission loss, but also radiates electromagnetic interference into the surrounding space, affecting the normal operation of surrounding electronic devices. Meanwhile, the shielded coil 6 forms an independent power supply circuit with the external control circuit through the shielded wire 61. At the same time as the electromagnetic coil 2 is supplied with a high-frequency alternating charging current, the external control circuit simultaneously supplies the shielded coil 6 with the same current as the electromagnetic coil 2 through the shielded wire 61. According to Ampere's circuital law and the principle of vector superposition of electromagnetic fields, the high-frequency alternating current flowing in the opposite direction generates a reverse alternating magnetic field in the surrounding space of the shielded coil 6. This reverse alternating magnetic field has the opposite propagation direction and the same magnetic field amplitude as the leakage magnetic field of the outer ring of the electromagnetic coil 2. This reverse alternating magnetic field will form vector cancellation with the leakage magnetic field radially scattered by the electromagnetic coil 2 in the same space. This neutralizes and cancels the leakage magnetic field lines that originally radiated outward by the magnetic field lines of the reverse magnetic field, greatly attenuating the stray leakage magnetic field of the electromagnetic coil 2 from the source of the magnetic field generation. At the same time, the shielded coil 6 is set in the radial region of the outer ring of the electromagnetic coil 2, and the reverse magnetic field it generates only acts on the spatial range of leakage magnetic radiation. It will not interfere with the main coupling magnetic field between the electromagnetic coil 2 and the receiving coil, ensuring that the energy transmission efficiency of wireless charging is not affected.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wireless charging coil module with a magnetic core (4) without a surrounding edge, comprising a bracket (1) and an electromagnetic coil (2) that generates a changing magnetic field to charge a device, wherein the electromagnetic coil (2) is coaxially mounted on the bracket (1), characterized in that: A magnetic core (4) without a circumferential ring limiting edge is assembled between the electromagnetic coil (2) and the bracket (1) to fix the electromagnetic coil (2). A cylindrical limiting boss (41) that restricts the displacement of the electromagnetic coil (2) is fixed on the top surface of the magnetic core (4). The electromagnetic coil (2) is formed by winding multiple strands of enameled wire.

2. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 1, characterized in that: Under the same rated charging power conditions, the number of coils of the electromagnetic coil (2) mounted on the magnetic core (4) without a perimeter ring limiting edge is greater than the number of coils of the electromagnetic coil (2) mounted on the same specification magnetic core (4) with a perimeter ring limiting edge, and the increased number of coils of the electromagnetic coil (2) compensates for the performance loss of the magnetic core (4) without a perimeter ring limiting edge.

3. A wireless charging coil module with a magnetic core (4) without a surrounding edge as described in claim 1, characterized in that: The magnetic core (4) is coaxially assembled with the electromagnetic coil (2), the limiting boss (41) is coaxially fixed with the magnetic core (4), and the outer diameter of the limiting boss (41) is adapted to the inner diameter of the electromagnetic coil (2).

4. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 3, characterized in that: The diameter of the magnetic core (4) is larger than the diameter of the electromagnetic coil (2).

5. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 1, characterized in that: The limiting boss (41) and the magnetic core (4) adopt an integrated structure.

6. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 1, characterized in that: The limiting boss (41) and the magnetic core (4) are separate independent components. The bottom of the limiting boss (41) is fixedly connected to the top surface of the magnetic core (4) through a cured adhesive layer.

7. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 1, characterized in that: An aluminum base (3) with a diameter larger than that of the magnetic core (4) is fixedly assembled between the magnetic core (4) and the bracket (1). A wire groove (5) is also machined on the magnetic core (4) and the aluminum base (3). The wire groove (5) contains a connecting wire (21) connected to the electromagnetic coil (2). A wire harness groove (12) matching the wire groove (5) is also machined on the bracket (1). The connecting wire (21) passes through the wire harness groove (12) and is connected to the external control circuit.

8. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 3, characterized in that: The top surface of the limiting boss (41) is higher than the top surface of the electromagnetic coil (2).

9. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 7, characterized in that: An annular magnet array (31) is also fixedly installed on the aluminum base (3), the inner diameter of the magnet array (31) being larger than the outer diameter of the magnetic core (4).

10. A wireless charging coil module with a magnetic core (4) without a surrounding edge according to claim 7, characterized in that: A shielding coil (6) with a diameter larger than that of the electromagnetic coil (2) is also coaxially fixed on the magnetic core (4). The current flowing through the shielding coil (6) is opposite to that of the electromagnetic coil (2), and shielding wires (61) are connected to both ends of the shielding coil (6). The shielding wires (61) pass through the wire harness groove (12) and are connected to the external control circuit.

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