Ultra-thin miniature mechanical fan and its assembly method

Abstract

This invention discloses an ultra-thin micro mechanical fan and its assembly method, comprising a base, a rotor assembly, and a stator assembly. A central tube is integrally injection-molded from the upper surface of the base. The rotor assembly includes a shaft core and fan blades, with the shaft core inserted into the central tube and the fan blades sleeved outside the shaft core. The stator assembly includes a PCB stator board. An annular limiting groove is provided around the outer periphery of the base, and the PCB stator board is installed and fixed within the annular limiting groove. A solder pad structure is provided at the end of the PCB stator board away from the fan blades. The central tube, integrally injection-molded from the base and used as a bearing, and the annular limiting groove directly install and fix the PCB stator board. The PCB stator board replaces the self-adhesive coil stator. This eliminates the wall thickness space of the oil-impregnated bearing itself and the wall thickness superposition space required for the base central tube and bearing to fit together, while also eliminating the traditional FPC flexible circuit board and adhesive backing structure, saving the axial thickness of the FPC and adhesive backing.

Description

Technical Field

[0001] This invention relates to the field of ultra-thin fans, and in particular to an ultra-thin micro mechanical fan and its assembly method. Background Technology

[0002] As portable electronic products such as smartphones, smart glasses, and smart wearable devices continue to develop towards thinner, lighter, and higher-performance designs, their internal integration is constantly increasing, and their space is becoming increasingly compact, placing extremely stringent requirements on the size of heat dissipation systems.

[0003] While traditional miniature mechanical fans can meet the heat dissipation needs of conventional equipment, they have many structural defects that are difficult to overcome when adapted to ultra-miniaturized devices.

[0004] Currently, mass-produced micro mechanical fans generally use oil-impregnated bearing structures. To ensure service life, the bearing wall thickness needs to be greater than 0.5mm. In addition, the wall thickness of the tube in the base is at least 0.3mm. The bearing system alone occupies at least 0.8mm of radial space, becoming the main bottleneck for size reduction. Stator assemblies mostly use self-adhesive coil structures. When the size is extremely small, the winding mold rod is close to the processing limit. Moreover, the welding point between the coil and the FPC (flexible printed circuit board) is located on the side of the stator, which will further occupy radial space. In terms of fixing method, the traditional stator needs to be welded to the FPC first, and then the FPC is fixed to the base with adhesive. The thickness of the FPC plus adhesive is usually 0.10-0.15mm. This structure cannot be eliminated, constituting a rigid limitation on axial height. Corresponding to the above structure, the existing conventional assembly methods for miniature fans have the following inherent defects, making them unsuitable for the mass production requirements of ultra-miniaturized fans: First, the existing assembly methods require a separate oil-impregnated bearing press-fitting process. To ensure the structural strength of the base tube during press-fitting, the tube wall thickness cannot be further reduced, which instead exacerbates the occupation of radial space. Moreover, the press-fitting process is prone to causing tube deformation and bearing coaxiality deviation. Under extremely small size specifications, the press-fitting positioning accuracy cannot be guaranteed, which not only further compresses the usable space between the stator and the fan blades but also easily leads to problems such as uneven motor air gap, high fan operating noise, and rapid wear; Second, the assembly of existing self-adhesive coil stators requires... The winding process involves multiple steps, including winding, plastic coating, and side welding. The winding process for extremely small dimensions is already close to the equipment limit, resulting in a very low yield rate. Furthermore, the side welding process is prone to problems such as weld protrusion and incomplete welding, requiring additional radial installation space, which further limits the reduction of the stator outer diameter and prevents the overall width of the fan from being increased. Thirdly, the existing stator fixing process requires three steps in sequence: stator to FPC welding, back adhesive bonding, and FPC to base bonding. The process is cumbersome, and the cumulative effect of assembly errors is significant. Moreover, the positioning accuracy of the back adhesive bonding is poor, and it is prone to debonding failure under high temperature and high humidity environments. At the same time, the fixing structure of FPC with back adhesive must reserve a fixing thickness during assembly. Therefore, a new technical solution needs to be researched to address the above problems. Summary of the Invention

[0005] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide an ultra-thin micro mechanical fan and assembly method. The base is integrally injection molded into a central tube, which also serves as a bearing. The annular limiting groove is used to directly install and fix the PCB stator board, and the PCB stator board replaces the self-adhesive coil stator. In this way, the wall thickness space of the oil-impregnated bearing itself and the wall thickness superposition space required for the base central tube to cooperate with the bearing are eliminated, while the traditional FPC flexible circuit board and adhesive backing structure are also eliminated, saving the axial thickness of FPC and adhesive backing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An ultra-thin miniature mechanical fan includes a base, a rotor assembly, and a stator assembly; The upper end face of the base is integrally injection molded with a central tube, which also serves as a bearing to support the rotor assembly; the rotor assembly includes a shaft core and fan blades, the shaft core is inserted into the central tube, and the fan blades are sleeved on the outside of the shaft core; The stator assembly includes a PCB stator board for controlling the rotation of the rotor assembly. The base is provided with an annular limiting groove around the outer periphery of the central tube for mounting and fixing the PCB stator board. The PCB stator board is mounted and fixed in the annular limiting groove. The PCB stator board has a pad structure for electrical connection with an external drive at the end away from the fan blades.

[0007] As a preferred option, the base is made of low-friction plastic material, and the middle tube and the base are integrally formed by injection molding, eliminating the need for subsequent assembly.

[0008] As a preferred embodiment, the annular limiting groove includes an annular extension section extending upward from the top surface of the base and an annular limiting part extending from the upper end of the annular extension section, wherein the annular extension section and the annular limiting part form an annular limiting groove. The outer periphery of the PCB stator board is provided with an annular chamfer edge. When the PCB stator board is installed in the annular limiting groove, the annular limiting part abuts against the upper edge of the annular chamfer edge, so that the annular limiting part axially limits the annular chamfer edge. By the annular limiting part extending inward abutting against the annular chamfer edge of the PCB stator, reliable axial limiting of the PCB stator is achieved, preventing axial movement during operation. The annular chamfer edge plays a guiding role during assembly, making it easy for the PCB stator to quickly snap into the annular limiting groove, thus improving the efficiency of automated assembly.

[0009] As a preferred embodiment, the outer periphery of the annular chamfered edge is provided with multiple circumferential positioning grooves at intervals along the circumferential direction. When the PCB stator is installed in the annular limiting groove, the sidewall of the circumferential positioning groove abuts against the sidewall of the annular extension section. Through the rigid abutment between the circumferential positioning groove on the outer periphery of the PCB stator and the sidewall of the annular extension section, the circumferential rotation of the PCB stator around the central axis is effectively restricted, ensuring that the circumferential relative position of the stator and rotor magnets is fixed, and avoiding the problem of motor failure or burnout caused by magnetic field phase disorder.

[0010] As a preferred embodiment, the PCB stator board is also provided with a through hole, and when the PCB stator board is installed in the annular positioning groove, the PCB stator board is sleeved on the outside of the middle tube.

[0011] As a preferred embodiment, the base is further provided with a top cover and a side frame. The top cover is fastened to the side frame, so that the top cover, the side frame and the base form a receiving cavity. The stator assembly and the rotor assembly are both disposed in the receiving cavity. The rotor assembly also includes a motor housing and a magnet. The motor housing is fixedly connected to the upper end of the shaft core. The magnet is fixed to the inner wall of the motor housing and is disposed opposite to the PCB stator board. The fan blade is fixed to the outer wall of the motor housing.

[0012] As a preferred embodiment, the PCB stator includes a coil layer and a connection layer. The connection layer is used to lead the coils of the coil layer to the pad structure of the PCB stator. The coil layer is specifically used to generate a driving magnetic field, and the connection layer is specifically used for electrical connection, making the layout of the PCB stator more reasonable and effectively utilizing the limited board space. The connection layer leads the coils of the coil layer directly to the bottom pad, avoiding the problem of needing to solder additional leads in traditional coil stators, reducing soldering processes and improving production efficiency.

[0013] As a preferred embodiment, the pad structure includes U-end pads, V-end pads, W-end pads, and COM-end pads spaced at the bottom of the PCB stator board. It adopts a three-phase four-wire pad layout, which is compatible with mainstream brushless DC motor drive schemes, ensuring smooth motor operation and low noise. The design of four independent pads facilitates reliable electrical connection with external drive circuits.

[0014] An assembly method for an ultra-thin micro mechanical fan, based on the ultra-thin micro mechanical fan, includes the following assembly steps: S1 Base Molding: The base is made using injection molding. An upwardly extending central tube is integrally injection molded on the upper end face of the base, so that the central tube also serves as a bearing to support the rotor assembly. At the same time, an annular extension section and an annular limiting part are integrally molded on the outer periphery of the base corresponding to the central tube. The annular extension section and the annular limiting part form an annular limiting groove for mounting the PCB stator board. S2 stator fabrication: Prefabricate a PCB stator board, open through holes on the PCB stator board, and prefabricate a pad structure for electrical connection with external drive circuit at the end of the PCB stator board away from the fan blades, and prefabricate an annular chamfer edge on the outer periphery of the PCB stator board. S3 Stator Fixing: The PCB stator board is fitted onto the outer periphery of the central tube through its through hole. The PCB stator board is then embedded into the annular limiting groove. The annular limiting part is heat-melted so that the heat-melted annular limiting part abuts against the upper edge of the annular chamfered edge, thereby completing the axial limiting and circumferential positioning of the PCB stator board on the base. S4 Rotor Prefabrication: Prepare a rotor assembly, which includes a shaft core, a motor housing, a magnet, and fan blades. Fix the magnet to the inner wall of the motor housing, fix the fan blades to the outer wall of the motor housing, and fix the center of the motor housing to the upper end of the shaft core. S5 rotor assembly: Insert the rotor assembly shaft into the central tube of the base, so that the magnet on the inner wall of the motor housing is positioned opposite to the PCB stator board, so as to complete the rotational engagement assembly of the rotor assembly and the stator assembly. S6 Complete Assembly: A side frame is set on the outer periphery of the base, and the top cover is fastened to the upper end of the side frame, so that the top cover, side frame and base form a closed receiving cavity, and the stator assembly and rotor assembly are housed in the receiving cavity to complete the overall assembly of the ultra-thin micro mechanical fan.

[0015] As a preferred embodiment, in step S2, multiple circumferential positioning grooves are prefabricated at intervals along the circumferential direction on the outer periphery of the annular chamfer edge; in step S3, when the PCB stator board is embedded into the annular limiting groove, the sidewall of the circumferential positioning groove abuts against the sidewall of the annular extension section to form the circumferential pre-positioning of the PCB stator board.

[0016] Compared with the prior art, the present invention has significant advantages and beneficial effects. Specifically, as can be seen from the above technical solution, Its main feature is that the base is integrally injection molded into the central tube, which also serves as the bearing. The shaft core directly mates with the inner wall of the central tube for rotation, thereby eliminating the traditional oil-impregnated bearing component. This saves the wall thickness space of the oil-impregnated bearing itself and the wall thickness superposition space required for the central tube and the bearing to mate. In this way, the radial space occupied by the bearing wall thickness is saved, the overall radial dimension of the central tube is reduced, the assembly gap between the bearing and the base is eliminated, and the coaxiality of the rotor rotation is improved. Moreover, the central tube and the base are integrally injection molded, eliminating the separate processing and assembly process of the bearing. Next, the PCB stator board is directly installed and fixed through the annular limiting groove on the base, eliminating the traditional FPC flexible circuit board and adhesive backing structure, saving the axial thickness of the FPC and adhesive backing, which can be used to increase the effective axial height of the fan blades and improve the fluid performance of the fan; at the same time, the annular limiting groove achieves radial and axial limiting of the PCB stator board through a snap-fit ​​method; and by replacing the self-adhesive coil stator with the PCB stator board, the electrical connection points are moved to the bottom of the stator, eliminating the occupation of radial space by the side solder joints, effectively reducing the overall outer diameter of the stator; Secondly, the pad structure is used for electrical connection with the external drive circuit, realizing the separation design of the fan body and the drive circuit. The fan does not need to integrate the drive chip and related circuits, further reducing the overall size and thickness of the fan; at the same time, the external drive circuit can be flexibly configured according to the needs of different devices, improving the fan's versatility and adaptability. Furthermore, this assembly method optimizes and releases radial and axial space, which can be fully utilized to expand the effective fluid space of the fan blades. While maximizing the overall size of the fan, it also maximizes the air delivery capacity of the fan blades. It eliminates multiple redundant assembly processes such as oil-impregnated bearing press-fitting, coil winding, FPC welding, and adhesive bonding, integrating the axial fixing and circumferential positioning of the stator into a single-step hot-melt process. This significantly shortens the assembly process, reduces the types of materials and assembly stations, and lowers the processing difficulty for extremely small dimensions. Simultaneously, single-process assembly effectively avoids the accumulation of assembly errors from multiple processes. This reduces the probability of defects such as structural deformation, positioning deviation, and poor soldering and debonding in the manufacturing process, improves mass production yield, reduces production and manufacturing costs, and adapts to the needs of large-scale mass production. At the same time, by replacing the traditional self-adhesive coil stator with a PCB stator board and using the process of prefabricating the solder pad structure on the bottom of the stator board, the radial space occupied by the solder points on the side of the stator is eliminated, and the outer diameter of the stator is significantly reduced. In addition, the hot melt fixing process replaces the traditional FPC and adhesive fixing method, directly eliminating the assembly step of FPC and adhesive, simplifying the assembly process, reducing the difficulty of the manufacturing process, and improving mass production efficiency and yield. Furthermore, the annular limiting groove integrally formed on the base enables precise pre-installation and positioning of the PCB stator board. Combined with the hot-melt process, the annular limiting part stably abuts against the annular chamfered edge of the stator board, simultaneously completing axial limiting and circumferential positioning. This effectively ensures the coaxiality of the stator and rotor, making the motor air gap uniform and consistent, and reducing fan operating noise. At the same time, the standardized injection molding and hot-melt processes effectively ensure the consistency of assembly precision for different batches of products, thereby ensuring the stable and controllable performance of core components such as air volume and air pressure.

[0017] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0018] Figure 1 This is a perspective view of an embodiment of the present invention; Figure 2 This is a cross-sectional view of an embodiment of the present invention; Figure 3 This is another cross-sectional view of an embodiment of the present invention; Figure 4 This is an exploded view of an embodiment of the present invention; Figure 5 This is a perspective view of the connection between the external drive and the PCB stator board in an embodiment of the present invention; Figure 6 This is a cross-sectional view of the connection between the external drive and the PCB stator board in an embodiment of the present invention; Figure 7 This is a structural diagram of a PCB stator board according to an embodiment of the present invention; Figure 8 yes Figure 2 A magnified view of a section at point A in the middle; Figure 9 yes Figure 3 A magnified view of a section at point B in the middle.

[0019] Explanation of reference numerals in the attached diagram: 10. Base; 11. Middle tube; 12. Top cover; 13. Side frame; 14. Receiving cavity; 20. Rotor assembly; 21. Shaft core; 22. Fan blades; 23. Motor housing; 24. Magnet; 30. Stator assembly; 31. PCB stator board; 32. Annular limiting groove; 33. Pad structure; 311. Circumferential chamfered edge; 312. Circumferential positioning groove; 313. Through hole; 321. Annular extension section; 322. Annular limiting part; 331, U-end pad; 332, V-end pad; 333, W-side pad; 334, COM-side pad; 40. External drive. Detailed Implementation

[0020] Please refer to Figures 1 to 9 As shown, it illustrates the specific structure of an embodiment of the present invention.

[0021] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0022] An ultra-thin micro mechanical fan includes a base 10, a rotor assembly 20, and a stator assembly 30.

[0023] The upper end face of the base 10 is integrally injection molded with a central tube 11, which serves as a bearing to support the rotor assembly 20. Preferably, the base 10 is also provided with an upper cover 12 and a side frame 13. The upper cover 12 is fastened to the side frame 13, so that the upper cover 12, the side frame 13 and the base 10 form a receiving cavity 14, and the stator assembly 30 and the rotor assembly 20 are both located in the receiving cavity 14.

[0024] Preferably, the base 10 is made of low-friction plastic material, and the middle tube 11 and the base 10 are integrally formed by injection molding, without the need for subsequent assembly; at the same time, low-friction wear-resistant plastic can be selected, so that the middle tube 11 has both bearing support and wear resistance functions, without the need to set up an additional independent wear-resistant plate, further reducing the number of parts and reducing manufacturing costs.

[0025] It should be noted that the coefficient of friction of the low-friction plastic material is less than 0.15; the low-friction plastic material can be a composite material made of LCP and PTFE, or a composite material made of LCP, PTFE and graphite. All of these low-friction plastic materials are modified composite materials that can be conventionally prepared through melt blending processes in the field of polymer materials. When using composite materials made of LCP and PTFE, LCP resin and PTFE powder can be mixed in a high-speed mixer to obtain a uniform mixture; the mixture is added to a twin-screw extruder, melt-blended and extruded into granules to obtain low-friction plastic granules; the granules are then injection molded into a base. The high-speed mixer and twin-screw extruder are well-known technologies in the field and will not be described in detail here.

[0026] The rotor assembly 20 includes a shaft core 21 and a fan blade 22. The shaft core 21 is inserted into the middle tube 11, and the fan blade 22 is sleeved on the outside of the shaft core 21. Preferably, the rotor assembly 20 also includes a motor housing 23 and a magnet 24. The motor housing 23 is fixedly connected to the upper end of the shaft core 21, the magnet 24 is fixed to the inner wall of the motor housing 23 and is arranged opposite to the PCB stator board 31, and the fan blade 22 is fixed to the outer wall of the motor housing 23.

[0027] The stator assembly 30 includes a PCB stator plate 31 for controlling the rotation of the rotor assembly 20. The base 10 is provided with an annular limiting groove 32 around the outer periphery of the central tube 11 for mounting and fixing the PCB stator plate 31. The PCB stator plate 31 is mounted and fixed in the annular limiting groove 32. Preferably, the annular limiting groove 32 includes an annular extension section 321 extending upward from the top surface of the base 10 and an annular limiting part 322 extending from the upper end of the annular extension section 321, and the annular extension section 321 and the annular limiting part 322 form an annular limiting groove 32. The outer periphery of the PCB stator board 31 is provided with an annular chamfer edge 311. When the PCB stator board 31 is installed in the annular limiting groove 32, the annular limiting part 322 abuts against the upper edge of the annular chamfer edge 311, so that the annular limiting part 322 axially limits the annular chamfer edge. By the annular limiting part 322 extending inward abutting against the annular chamfer edge 311 of the PCB stator, the reliable axial limiting of the PCB stator is achieved, preventing axial movement during operation. The annular chamfer edge 311 plays a guiding role during assembly, making it easy for the PCB stator to quickly snap into the annular limiting groove 32, thereby improving the efficiency of automated assembly.

[0028] Preferably, the outer periphery of the annular chamfered edge is provided with a plurality of circumferential positioning grooves 312 at intervals along the circumferential direction. When the PCB stator is installed in the annular limiting groove 32, the sidewall of the circumferential positioning groove 312 abuts against the sidewall of the annular extension 321. Through the rigid abutment between the circumferential positioning groove 312 on the outer periphery of the PCB stator and the sidewall of the annular extension 321, the circumferential rotation of the PCB stator around the central axis is effectively restricted, ensuring that the circumferential relative position of the stator and the rotor magnet 24 is fixed, and avoiding the problem of motor failure or burnout caused by magnetic field phase disorder.

[0029] Preferably, the PCB stator board 31 is further provided with a through hole 313, and when the PCB stator board 31 is installed in the annular positioning groove, the PCB stator board 31 is sleeved on the outside of the middle tube 11.

[0030] The PCB stator board 31 has a pad structure 33 for electrical connection with the external drive 40 at the end away from the fan blade 22.

[0031] Preferably, the PCB stator board 31 includes a coil layer and a connection layer. The connection layer is used to lead the coil of the coil layer to the pad structure 33 of the PCB stator board 31. The coil layer is specifically used to generate a driving magnetic field, and the connection layer is specifically used for electrical connection, making the layout of the PCB stator more reasonable and effectively utilizing the limited board space. The connection layer directly leads the coil of the coil layer to the bottom pad, avoiding the problem of needing additional soldering leads in traditional coil stators, reducing soldering processes, and improving production efficiency. The coil layer and connection layer also refer to the coil area and the trace area, respectively. The trace area is used for leading the coil ends of the coil layer to the pad structure 33 via traced coils.

[0032] Preferably, the pad structure 33 includes a U-end pad 331, a V-end pad 332, a W-end pad 333, and a COM-end pad 334 spaced at the bottom of the PCB stator board 31. It adopts a three-phase four-wire pad layout, which is compatible with mainstream brushless DC motor drive schemes, ensuring smooth motor operation and low noise. The design of four independent pads facilitates reliable electrical connection with the external drive circuit 40. Whether using Pogo pin elastic contact or thermoforming connection, good conductivity and connection stability can be guaranteed.

[0033] In this embodiment, the ultra-thin micro fan does not contain a drive circuit. The external drive 40 contacts the U-end pad 331, V-end pad 332, W-end pad 333 and COM-end pad 334 through four Pogo pins. The Pogo pins are located on the electronic device, and the drive circuit is also located on the electronic device. Alternatively, the ultra-thin micro fan may not contain a drive circuit. The external drive 40 is thermally bonded to the PCB stator via four pads: the U-end pad 331, V-end pad 332, W-end pad 333, and COM-end pad 334.

[0034] In this embodiment, when the ratio of the fan blade HUB diameter to the fan width is less than 50%, the fluid space is extremely considerable. The measured data below shows that the maximum air volume can reach 0.15 CFM and the maximum air pressure can reach 8.2 mmAq, which is expected to solve about 1W of heat dissipation.

[0035]

[0036] An assembly method for an ultra-thin micro mechanical fan, based on the ultra-thin micro mechanical fan, includes the following assembly steps: S1 Base Molding: The base 10 is prepared by injection molding. An upwardly extending central tube 11 is integrally injection molded on the upper end surface of the base 10, so that the central tube 11 also serves as a bearing to support the rotor assembly 20. At the same time, an annular extension section 321 and an annular limiting part 322 are integrally formed on the outer periphery of the base 10 corresponding to the central tube 11. The annular extension section 321 and the annular limiting part 322 form an annular limiting groove 32 for mounting the PCB stator board. S2 stator preparation: a PCB stator board 31 is prefabricated, through holes 313 are opened on the PCB stator board 31, and a pad structure 33 for electrical connection with the external drive circuit 40 is prefabricated at the end of the PCB stator board 31 away from the fan blade 22, and an annular chamfer edge 311 is prefabricated on the outer periphery of the PCB stator board 31. S3 Stator Fixing: The PCB stator board 31 is fitted onto the outer periphery of the central tube 11 through its through hole 313. The PCB stator board 31 is embedded into the annular limiting groove 32. The annular limiting part 322 is heat-melted so that the heat-melted annular limiting part 322 abuts against the upper edge of the annular chamfered edge 311 to complete the axial limiting and circumferential positioning of the PCB stator board 31 on the base 10. S4 Rotor Prefabrication: Prepare rotor assembly 20, which includes shaft core 21, motor housing 23, magnet 24 and fan blade 22. Fix magnet 24 to the inner wall of motor housing 23, fix fan blade 22 to the outer wall of motor housing 23, and fix the center part of motor housing 23 to the upper end of shaft core 21. S5 Rotor Assembly: Insert the shaft core 21 of the rotor assembly 20 into the middle tube 11 of the base 10, so that the magnet 24 on the inner wall of the motor housing 23 is positioned opposite to the PCB stator board 31, so as to complete the rotational engagement assembly of the rotor assembly 20 and the stator assembly 30. S6 Complete Assembly: A side frame 13 is provided on the outer periphery of the base 10, and the upper cover 12 is fastened to the upper end of the side frame 13, so that the upper cover 12, the side frame 13 and the base 10 form a closed receiving cavity 14, and the stator assembly 30 and the rotor assembly 20 are housed in the receiving cavity 14 to complete the overall assembly of the ultra-thin micro mechanical fan.

[0037] Preferably, in step S2, multiple circumferential positioning grooves 312 are prefabricated at intervals along the circumferential direction on the outer periphery of the annular chamfered edge 311; in step S3, when the PCB stator board 31 is embedded into the annular limiting groove 32, the sidewall of the circumferential positioning groove 312 abuts against the sidewall of the annular extension section 321 to form the circumferential pre-positioning of the PCB stator board 31, realizing the precise pre-positioning of the PCB stator board 31. Combined with the hot melt process, the annular limiting part stably abuts against the annular chamfered edge of the stator board, and the axial limiting and circumferential positioning are completed simultaneously, effectively ensuring the coaxiality of the stator and rotor, making the air gap of the motor uniform and consistent, and reducing the noise of the fan operation; at the same time, the standardized injection molding and hot melt process effectively ensures the consistency of assembly accuracy of different batches of products, thereby ensuring the stability and controllability of core performance such as air volume and air pressure.

[0038] The key design feature of this invention is that it uses an integral injection-molded base to form a central tube that also functions as a bearing. The shaft core directly engages with the inner wall of the central tube for rotation, eliminating the need for traditional oil-impregnated bearing components. This saves the wall thickness space of the oil-impregnated bearing itself and the wall thickness overlap space required for the central tube and bearing to mate. As a result, it saves the radial space occupied by the bearing wall thickness, reduces the overall radial dimension of the central tube, eliminates the assembly gap between the bearing and the base, and improves the coaxiality of the rotor rotation. Furthermore, the integral injection molding of the central tube and the base eliminates the need for separate processing and assembly of the bearing. Next, the PCB stator board is directly installed and fixed through the annular limiting groove on the base, eliminating the traditional FPC flexible circuit board and adhesive backing structure, saving the axial thickness of the FPC and adhesive backing, which can be used to increase the effective axial height of the fan blades and improve the fluid performance of the fan; at the same time, the annular limiting groove achieves radial and axial limiting of the PCB stator board through a snap-fit ​​method; and by replacing the self-adhesive coil stator with the PCB stator board, the electrical connection points are moved to the bottom of the stator, eliminating the occupation of radial space by the side solder joints, effectively reducing the overall outer diameter of the stator; Secondly, the pad structure is used for electrical connection with the external drive circuit, realizing the separation design of the fan body and the drive circuit. The fan does not need to integrate the drive chip and related circuits, further reducing the overall size and thickness of the fan; at the same time, the external drive circuit can be flexibly configured according to the needs of different devices, improving the fan's versatility and adaptability. Furthermore, this assembly method optimizes and releases radial and axial space, which can be fully utilized to expand the effective fluid space of the fan blades. While maximizing the overall size of the fan, it also maximizes the air delivery capacity of the fan blades. It eliminates multiple redundant assembly processes such as oil-impregnated bearing press-fitting, coil winding, FPC welding, and adhesive bonding, integrating the axial fixing and circumferential positioning of the stator into a single-step hot-melt process. This significantly shortens the assembly process, reduces the types of materials and assembly stations, and lowers the processing difficulty for extremely small dimensions. Simultaneously, single-process assembly effectively avoids the accumulation of assembly errors from multiple processes. This reduces the probability of defects such as structural deformation, positioning deviation, and poor soldering and debonding in the manufacturing process, improves mass production yield, reduces production and manufacturing costs, and adapts to the needs of large-scale mass production. At the same time, by replacing the traditional self-adhesive coil stator with a PCB stator board and using the process of prefabricating the solder pad structure on the bottom of the stator board, the radial space occupied by the solder points on the side of the stator is eliminated, and the outer diameter of the stator is significantly reduced. In addition, the hot melt fixing process replaces the traditional FPC and adhesive fixing method, directly eliminating the assembly step of FPC and adhesive, simplifying the assembly process, reducing the difficulty of the manufacturing process, and improving mass production efficiency and yield. Furthermore, the annular limiting groove integrally formed on the base enables precise pre-installation and positioning of the PCB stator board. Combined with the hot-melt process, the annular limiting part stably abuts against the annular chamfered edge of the stator board, simultaneously completing axial limiting and circumferential positioning. This effectively ensures the coaxiality of the stator and rotor, making the motor air gap uniform and consistent, and reducing fan operating noise. At the same time, the standardized injection molding and hot-melt processes effectively ensure the consistency of assembly precision for different batches of products, thereby ensuring the stable and controllable performance of core components such as air volume and air pressure.

[0039] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. An ultra-thin miniature mechanical fan, characterized in that: It includes a base, a rotor assembly, and a stator assembly; The upper end face of the base is integrally injection molded with a central tube, which also serves as a bearing to support the rotor assembly; the rotor assembly includes a shaft core and fan blades, the shaft core is inserted into the central tube, and the fan blades are sleeved on the outside of the shaft core; The stator assembly includes a PCB stator board for controlling the rotation of the rotor assembly. The base is provided with an annular limiting groove around the outer periphery of the central tube for mounting and fixing the PCB stator board. The PCB stator board is mounted and fixed in the annular limiting groove. The PCB stator board has a pad structure for electrical connection with an external drive at the end away from the fan blades.

2. The ultra-thin micro mechanical fan according to claim 1, characterized in that: The base is made of low-friction plastic.

3. The ultra-thin micro mechanical fan according to claim 1, characterized in that: The annular limiting groove includes an annular extension section extending upward from the top surface of the base and an annular limiting part extending from the upper end of the annular extension section, and the annular extension section and the annular limiting part together form an annular limiting groove. The outer periphery of the PCB stator board is provided with an annular chamfer edge. When the PCB stator board is installed in the annular limiting groove, the annular limiting part abuts against the upper edge of the annular chamfer edge, so that the annular limiting part limits the annular chamfer edge axially.

4. The ultra-thin micro mechanical fan according to claim 3, characterized in that: The outer periphery of the annular chamfered edge is provided with multiple circumferential positioning grooves at intervals along the circumferential direction. When the PCB stator is installed in the annular limiting groove, the sidewall of the circumferential positioning groove abuts against the sidewall of the annular extension section.

5. The ultra-thin micro mechanical fan according to claim 1, characterized in that: The PCB stator board is also provided with a through hole. When the PCB stator board is installed in the annular positioning groove, the PCB stator board is sleeved on the outside of the middle tube.

6. The ultra-thin micro mechanical fan according to claim 1, characterized in that: The base is also provided with a top cover and a side frame. The top cover is fastened to the side frame, so that the top cover, the side frame and the base form a receiving cavity. The stator assembly and the rotor assembly are both located in the receiving cavity. The rotor assembly also includes a motor housing and a magnet. The motor housing is fixedly connected to the upper end of the shaft core, the magnet is fixed to the inner wall of the motor housing and is arranged opposite to the PCB stator board, and the fan blade is fixed to the outer wall of the motor housing.

7. The ultra-thin micro mechanical fan according to claim 5, characterized in that: The PCB stator includes a coil layer and a connection layer, wherein the connection layer is used to lead the coil of the coil layer to the pad structure of the PCB stator.

8. The ultra-thin micro mechanical fan according to claim 1, characterized in that: The pad structure includes U-end pads, V-end pads, W-end pads and COM-end pads spaced at the bottom of the PCB stator board.

9. A method for assembling an ultra-thin miniature mechanical fan, characterized in that: Based on any one of claims 1 to 8, the ultra-thin micro mechanical fan includes the following assembly steps: S1 Base Molding: The base is made using injection molding. An upwardly extending central tube is integrally injection molded on the upper end face of the base, so that the central tube also serves as a bearing to support the rotor assembly. At the same time, an annular extension section and an annular limiting part are integrally molded on the outer periphery of the base corresponding to the central tube. The annular extension section and the annular limiting part form an annular limiting groove for mounting the PCB stator board. S2 stator fabrication: Prefabricate a PCB stator board, open through holes on the PCB stator board, and prefabricate a pad structure for electrical connection with external drive circuit at the end of the PCB stator board away from the fan blades, and prefabricate an annular chamfer edge on the outer periphery of the PCB stator board. S3 Stator Fixing: The PCB stator board is fitted onto the outer periphery of the central tube through its through hole. The PCB stator board is then embedded into the annular limiting groove. The annular limiting part is heat-melted so that the heat-melted annular limiting part abuts against the upper edge of the annular chamfered edge, thereby completing the axial limiting and circumferential positioning of the PCB stator board on the base. S4 Rotor Prefabrication: Prepare a rotor assembly, which includes a shaft core, a motor housing, a magnet, and fan blades. Fix the magnet to the inner wall of the motor housing, fix the fan blades to the outer wall of the motor housing, and fix the center of the motor housing to the upper end of the shaft core. S5 rotor assembly: Insert the rotor assembly shaft into the central tube of the base, so that the magnet on the inner wall of the motor housing is positioned opposite to the PCB stator board, so as to complete the rotational engagement assembly of the rotor assembly and the stator assembly. S6 Complete Assembly: A side frame is set on the outer periphery of the base, and the top cover is fastened to the upper end of the side frame, so that the top cover, side frame and base form a closed receiving cavity, and the stator assembly and rotor assembly are housed in the receiving cavity to complete the overall assembly of the ultra-thin micro mechanical fan.

10. The assembly method according to claim 9, characterized in that: In step S2, multiple circumferential positioning grooves are prefabricated at intervals along the circumferential direction on the outer periphery of the annular chamfer edge; in step S3, when the PCB stator board is embedded into the annular limiting groove, the sidewall of the circumferential positioning groove abuts against the sidewall of the annular extension section to form the circumferential pre-positioning of the PCB stator board.

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