Stator assembly, brushless motor, power tool and method of manufacturing a stator assembly

Abstract

The present application provides a kind of stator assembly, brushless motor, electric tool and the method for manufacturing stator assembly.The outer stator subassembly of the stator assembly includes a ring piece, which is molded with shell.Inner stator subassembly is fixedly connected to outer stator subassembly, and includes bearing for supporting rotor shaft.Also includes frame with multiple protrusions for supporting coil wound therearound;And integrally formed housing, its end face has recess receiving bearing;Wherein the shell is also molded around the protrusions.In further aspects, an electric tool is provided, which includes the motor assembly of the stator assembly.A method for manufacturing a stator assembly is also provided.The embodiments of the application not only significantly simplify the assembly process, reduce the difficulty and error rate of assembly, significantly improve the slot fill rate, and effectively improve the coaxiality of the motor, thereby enhancing the overall performance and stability.

Description

Technical Field

[0001] This application relates to the field of electric motors, and more particularly to a brushless DC motor, a stator assembly for the motor, and a method for manufacturing the same. Background Technology

[0002] Battery-powered power tools are typically equipped with motors that drive the shafts that connect to various tools. Brushless motors are widely used in these tools due to their higher durability, speed, and torque performance compared to brushed motors.

[0003] As is known to those skilled in the art, a brushless motor drives the rotor and attached shaft inside the stator to rotate by switching the current in the stator windings. Specifically, current is injected into the stator coils in sequence, forming changing electromagnetic poles on the periphery of the stator. These electromagnetic poles are excited in a predetermined order, attracting the opposite magnetic poles of the rotor, thereby generating torque to drive the motor shaft to rotate, and ultimately driving the driven parts of the power tool.

[0004] However, with the increasing market demand for miniaturized and high-power handheld power tools (such as electric drills), higher requirements are being placed on the compactness, efficiency, and production cost of motors and their components. Current technologies require motors to reduce size and improve energy efficiency while minimizing manufacturing time and cost.

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a brushless motor and stator assembly to solve or at least partially improve the problems of large size, low efficiency and high manufacturing cost of existing motors, and at the same time provide an optimized option for the market. Summary of the Invention

[0006] The features and advantages of this application will be set forth in detail in the following description. Some features and advantages may be derived directly from the description or learned by implementing the technical solutions disclosed in this application. The features and advantages of this application may be realized and obtained by the technical means and combinations thereof specifically pointed out in the claims.

[0007] According to a first aspect of this application, a stator assembly for a brushless motor is provided, the brushless motor having an internal rotor that rotates about an axis, the stator assembly comprising: an outer stator subassembly having an annular member; an inner stator subassembly housed within and fixedly attached to the outer stator subassembly, the inner stator subassembly comprising: a frame having an annular body and a plurality of protrusions extending outwardly from the annular body for supporting coils surrounding thereon; an integrally formed housing, wherein the housing and the frame are molded integrally; wherein the protrusions protrude from the housing to contact the annular member of the outer stator subassembly.

[0008] Preferably, the plurality of protrusions comprises a plurality of teeth extending radially outward from the periphery of the annular body of the frame and spaced apart from each other. Preferably, the frame is formed by riveting and stacking a plurality of ribbed and unribbed chips, thereby forming a plurality of holes between the teeth on the annular body. Preferably, the frame is composed of laminated metal or sheet metal.

[0009] Preferably, the annular member has a support member at least partially molded thereon, and the support member of the outer stator subassembly and the housing of the inner stator subassembly are made of an insulating material, preferably plastic, more preferably polyamide.

[0010] Preferably, the inner stator sub-assembly and the outer stator sub-assembly are fixedly connected at multiple locations where the protrusion contacts the annular member by laser welding or ultrasonic welding.

[0011] Preferably, the coil of the inner stator sub-assembly is wound by a machine operating outside the annular body of the inner stator sub-assembly.

[0012] Preferably, the ratio of the cross-sectional area of ​​the coil conductor of the toothed structure to the total usable area of ​​the coil of the toothed structure is on average between 45% and 55%.

[0013] Preferably, the inner stator subassembly further includes a bearing for supporting a shaft molded therein, wherein the bearing is received in a groove on the end face of the housing.

[0014] Preferably, the front end cover of the motor is connected to the stator assembly via pins and uses the same reference surface.

[0015] According to a second aspect of this application, a brushless motor is provided, comprising: a stator assembly according to a first aspect of this application; and a rotor assembly, one end of which is supported on a bearing of an inner stator sub-assembly within the inner stator assembly and substantially enclosed by its shaft to a frame of the stator assembly, wherein the rotor assembly includes a sheath molded therearound.

[0016] Furthermore, the brushless motor also includes a cooling fan and at least three control lines electrically connected to the stator coils.

[0017] According to a third aspect of this application, an electric tool is provided, including a brushless motor having a stator provided according to the first aspect.

[0018] According to a fourth aspect of this application, an electric tool is provided, including a brushless motor according to a second aspect.

[0019] A method for manufacturing a stator assembly is provided according to a fifth aspect of this application, comprising: molding a support member at least partially onto an annular member to form an outer stator subassembly; molding a housing onto a bearing and a frame to form an inner stator subassembly; the frame having a plurality of teeth extending radially outward from the annular body; arranging coil windings on the housing at positions corresponding to the teeth; housing the inner stator subassembly within the outer stator subassembly and welding them together. Preferably, the coil is formed on each tooth by winding wire from outside the frame of the inner stator subassembly.

[0020] The motor assembly according to the above embodiments is more convenient for winding, assembly, and user operation, and can wind more coils, resulting in a significant increase in slot fill factor. Furthermore, the motor assembly according to the embodiments of this application saves space, making the overall structure more compact and reducing costs. In addition, the bearing configuration of this application increases bearing push-out force, and the pin configuration ensures precise alignment between components through a single reference.

[0021] Therefore, the exemplary stator assembly, electric motor, power tool, and manufacturing method described herein advantageously provide an electric motor that is smaller, more efficient, and has a higher slot fill rate compared to conventional prior art electric motors. The embodiments of this application not only significantly simplify the assembly process, reduce assembly difficulty and error rate, and significantly improve slot fill rate, but also effectively improve the coaxiality of the motor, thereby enhancing overall performance and stability. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0023] Figure 1A An exploded perspective view of the lower part of a brushless motor assembly according to a first embodiment of this application is shown, wherein the stator coils have been removed for clarity.

[0024] Figure 1B for Figure 1A The image shown is a perspective view of the motor assembly in the assembled state according to the first embodiment of this application.

[0025] Figure 1C Depicting Figure 1A A side view of an embodiment of a motor assembly in an assembled state.

[0026] Figure 2A yes Figure 1A-1CAn exemplary assembly diagram of the stator assembly of the motor assembly shown.

[0027] Figure 2B yes Figure 2A An exploded 3D view of the internal sub-components of the middle stator assembly. For clarity, the stator coils have been removed.

[0028] Figure 2C It is based on Figure 2A An exploded perspective view of the exterior of the stator assembly in an embodiment of the motor assembly.

[0029] Figure 3 It shows Figure 1A An exemplary exploded perspective view of an exemplary rotor assembly of the motor assembly shown.

[0030] Figure 4 It shows Figure 2C Part of the outer stator assembly and Figure 2B An exemplary view of the exemplary engagement and fixed connection arrangement of the inner stator sub-components.

[0031] Figure 5 This is a perspective view of a motor according to the second embodiment of this application.

[0032] Figure 6A and 6B yes Figure 5 The diagram shown is an exploded view of the motor.

[0033] Figure 7A and 7B yes Figure 5 The diagram shows a three-dimensional view of the outer stator sub-assembly of the motor.

[0034] Figure 8 yes Figure 5 The diagram shows a three-dimensional view of the inner stator sub-assembly of the motor.

[0035] Figure 9A and 9B yes Figure 8 A three-dimensional view of the inner stator laminations of the inner stator sub-assembly shown.

[0036] Figures 10A-10C yes Figure 8 A three-dimensional view of the winding frame of the inner stator sub-assembly shown.

[0037] Figure 11A-11B A stator assembly with coil windings is shown.

[0038] Figure 12 yes Figure 5 The image shows a 3D view of the bearings of the motor. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments in this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification. Although specific implementation methods are discussed, it should be understood that this is for illustrative purposes only. Those skilled in the art will recognize that other components and configurations can be used without departing from the spirit and scope of this application.

[0040] Figure 1A This is an exploded perspective view of the lower part of a brushless motor assembly 110 with a stator assembly according to the first embodiment of this application. The motor is a four-pole, six-slot motor. The stator assembly includes an inner stator assembly 120 and an outer stator sub-assembly 130. It should be noted that, for clarity, Figure 1A The diagram shows the brushless motor assembly 110 after the stator coils, connecting wires, and top and bottom brackets have been removed.

[0041] As further described herein, the inner stator sub-assembly 120 includes a housing / shell 121 and a stator laminated frame 122, wherein the housing 121 and the stator laminated frame 122 are molded integrally, and therefore they are firmly joined together and inseparable. It should be noted that, for ease of explanation, Figure 1A They are presented in a separate form.

[0042] Preferably, the housing 121 is made of plastic (e.g., glass fiber reinforced polyamide AP66) or a similar material. Any other material is also possible and should not be considered outside the scope of this application, and it is integrated with the stator lamination frame. The housing 121 serves as an insulator and support member for the stator lamination frame 122.

[0043] The inner stator subassembly 120 includes a recess 126 in which the bearing 112 is removably held.

[0044] The motor assembly also includes a fan 114 disposed near the bearing 112 for directing cooling air over the stator coils and rotor to dissipate heat generated when current flows. The motor assembly also includes a gear 111 for driving the fan 114, housed in a base within the housing.

[0045] For clarity, Figure 1AThe two housing brackets for housing the brushless motor assembly 110 are omitted. Alternatively, a first housing bracket may be provided between the fan 114 and the motor assembly 110, and the first housing bracket member may engage with a corresponding member of the second housing bracket for receiving the motor assembly 110 in space to confine the motor assembly between the two housing brackets.

[0046] Preferably, the inner stator frame 122 is made of laminated steel or steel plate with a thickness of approximately 0.25 mm to minimize undesirable magnetic and electrical effects. In a further preferred embodiment of this application, the stator frame may include 1-3 steel laminates.

[0047] The outer stator subassembly 130 includes an outer ring or outer bead 132 and an inner shell 134, the inner shell 134 being molded together with the outer ring or outer bead 132. For example, the outer bead 132 is formed as an outer stator chip, and the inner shell 134 is formed as an overmolded inner shell. Preferably, the inner shell 134 is made of plastic (e.g., glass fiber reinforced polyamide). It is important to emphasize that the outer ring 132 and the inner shell 134 are cross-molded and the inner shell 134 is integrally overmolded with the outer ring 132, thus forming them as a single, inseparable unit, although they are depicted as separate in the figures for ease of illustration and explanation.

[0048] Similar to the outer shell 121, the inner shell 134 serves as an insulator and support member for the outer ring or circle 132.

[0049] Figure 1B A rotor assembly 140 according to one embodiment of this application is shown, which includes a rotor lamination portion 142 and a permanent magnet 144 supported therein.

[0050] Figure 1C It shows Figure 1A This is a perspective view of the motor assembly in its assembled state according to an embodiment of this application. The perspective view is provided for visual effect and ease of demonstration. Figure 1C The enclosed portion of rotor 140 has been removed. It is understood that, in the preferred arrangement, due to improvements in the inner and outer sub-assemblies of the stator and rotor described herein, the dimension “B” shown is 25% smaller than that in similar arrangements.

[0051] For the sake of completeness, Figure 1B and 1C This includes the wires forming the stator coils 160a-f and the connecting wires 162. Furthermore, in... Figure 1B and 1C In the middle, axis 150 is also visible.

[0052] Figure 2A yes Figure 1A-1CThe figure shows an exemplary assembled perspective view of the stator assembly in the motor assembly. As shown, the outer stator sub-assembly 130 includes an outer ring 132 and a housing 134, while the inner stator sub-assembly 120 has a housing 121 for support and a bearing 112. Preferably, the inner stator sub-assembly 120 is housed within the outer stator sub-assembly 130 and is fixedly connected together by laser welding, ultrasonic welding, or similar methods.

[0053] Typically, the stator laminations of the frame 122 of the inner stator subassembly 120 and the rotor laminations 142 of the rotor 140 comprise thin sheets of metal joined together by stacking, welding, bonding, riveting, or other means. The metal may be cobalt, nickel alloy, silicon, or thin-gauge electrical steel, with a thickness ranging from 0.25 mm to 0.5 mm. Those skilled in the art will appreciate that these laminations are made of individual sheets of metal electrically insulated from each other, rather than of solid sheets of metal, to minimize losses caused by eddy currents or hysteresis.

[0054] Figure 2B This is an exploded perspective view of the inner stator sub-assembly 120. The stator coils have been removed from this perspective view for clarity and to better illustrate its structure.

[0055] As shown in the exploded perspective view, the housing 121 accommodates the bearing 112 and the frame 122. The frame 122 has an annular body or a circular ring or hub 123. This embodiment has six toothed / stator elements 124 arranged to project radially outward from the circular ring or hub 123, thus forming a four-pole, six-slot configuration. Preferably, the width of the central hub is selected to be between 0.8 and 1.2 times the width of the air gap between the stator and rotor.

[0056] Stator element 124 is housed in a corresponding socket 128 within housing 121. Holes or slots in frame 122 reduce magnetic leakage and eddy currents. The size and location of these holes or slots reduce temperature, resistance, and magnetic field current within inner stator subassembly 120.

[0057] Typically, the width of these holes is 2-3 times the air gap between the rotor and stator, and extends substantially to most of the height of the frame 122. The width of the connection portion spanning these holes can be 0.8 to 1.2 times the air gap between the rotor and stator.

[0058] Understandably, the wires forming the coil can be wound from the outside of the housing onto the sockets in the stator element 124 and housing 121, rather than wound from the inside out as in the prior art. This allows the wires forming the coil to be packaged more tightly and neatly, and increases the slot fill ratio of the wires to the slot area due to the tighter winding. The tighter coil can enhance the electrical and magnetic properties of the stator.

[0059] It should also be understood that each stator element 124 can be equipped with a separate, removable, and reusable coil winding, or the coil can be wound onto the stator element 124 all at once. This winding improves efficiency and saves redundant coil end wires resulting from separate winding schemes.

[0060] In addition, the winding speed is much faster than the traditional inside-out winding method.

[0061] It is understood that there are several definitions of slot fill factor in scientific literature, but generally an electrical slot fill factor f is defined. cu and a mechanical slot fill factor f me .

[0062] Preferably, the electrical slot filling coefficient f cu The total cross-sectional area of ​​copper in the conductor (N) w A cu ) and the total cross-sectional area A of the channel slot .

[0063] In addition, the mechanical tank filling coefficient f me Defined as the total cross-sectional area of ​​the conductor (N) w A w ) and effective tank area A eff The ratio, the latter defined as the total cross-sectional area A of the channel. slot The difference between the area occupied by the slot insulation layer and the area occupied by the slot insulation layer. These two fill factors can be described by the following mathematical formula: where N w A represents the number of wires in the slot. cu A is the maximum copper cross-sectional area (useful cross-sectional area) of a single conductor. w This refers to the maximum cross-sectional area of ​​a single conductor (including its insulation).

[0064]

[0065]

[0066] Preferably, the shape of the slots in the stator frame can be selected to facilitate tight and compact winding of the wires forming the coil.

[0067] In an exemplary embodiment, a prior art stator (e.g.) Figure 1A-1C The stator shown has a conventional winding slot arrangement with a winding area of ​​56.8 mm² in one slot and a stator diameter of 48 mm. Using standard conventional methods, the fill rate of standard specification wire is close to 47% of the slot fill rate. Using a conventional winding machine, the stator winding time for all coils is approximately 76 seconds.

[0068] In contrast, according to the method and arrangement of this application, in a stator with a diameter of 48 mm and configured for external filling, the winding area in one slot is reduced to 49.9 mm², and the winding slot fill rate is increased to 65%, and possibly as high as 75%. Using a conventional winding machine, the time required to fill all slots is approximately 38 seconds, thus demonstrating a higher fill rate in a shorter time.

[0069] Figure 2C yes Figure 2A An exploded perspective view of the outer stator sub-assembly 130 of an embodiment of the motor assembly.

[0070] like Figure 2C As shown, the outer stator subassembly 130 has an outer ring 132 and an inner housing 134, the inner housing 134 being at least partially molded together with the outer ring 132 to generally surround the outer ring 132.

[0071] Similar to the outer shell 121, the inner shell 134 mainly serves as an insulator and support member for the outer ring 132.

[0072] Furthermore, Figure 2B The stator element 124 of the inner stator sub-assembly 120 shown can be coupled with Figure 2C The inner surface of the outer stator frame assembly 130 is engaged. In a preferred embodiment, each end of the stator element 124 is protruding, engaging a groove on the inner surface of the metal ring / housing 132, and protruding through a corresponding groove defined in the inner housing 134.

[0073] Figure 3 The image is shown in an exploded perspective view. Similarly, like the inner stator subassemblies and outer stator subassemblies, the rotor may also include molded closed ends 146, 148 molded around it. For ease of reference, these ends are depicted as spaced apart from the rotor, but it should be understood that in an actual rotor assembly, they are not easily separable once manufactured.

[0074] The molded ends 146, 148 of the rotor can replace the copper bushings used for balancing in prior art rotor assemblies. Preferably, the molded ends 146, 148 of the exemplary rotor of this application hold the components of the rotor assembly together and simplify the assembly process.

[0075] The rotor assembly 140 is supported on a shaft 150, one end of which is housed in a bearing 112. As described above, the bearing 112 is held within the housing of the inner stator subassembly 120.

[0076] Rotor assembly 140 and shaft 150 can be molded together with encapsulating plastic sheath to form a one-piece rotor assembly, but for clarity, the encapsulating sheath is not shown herein.

[0077] Figure 4This is an exemplary top view of a portion of the inner stator subassembly and the outer stator subassembly, indicating the location where they can be joined by laser or ultrasonic welding 160. In one embodiment, six stator elements 124 are provided.

[0078] The protrusions on the ends of the frame element 124 of the inner stator sub-assembly engage with the outer stator sub-assembly. The top and bottom surfaces of the inner and outer stator sub-assemblies are welded together at twelve locations (e.g., using ultrasonic or laser welding) near the engagement point between the ring / housing of each stator element and the outer stator sub-assembly. Figure 4 In the illustrated embodiment, six welding points 160 are shown from a top view of the stator assembly. These securely join the sub-assemblies together within the motor assembly.

[0079] Preferably, it is understood that the tools suitable for the motor stator assembly of this application may include any type of power tool, including impact drive, drill bit, saw, rotary hammer, etc.

[0080] In a second embodiment of this application, a brushless DC motor is provided. Compared to the first embodiment, the outer stator assembly of the brushless DC motor in the second embodiment is integrally formed as a ring structure, rather than consisting of an outer ring and an inner shell, reducing the number of components and making the structure more compact. Furthermore, the front end cover and the stator assembly are connected by pins, using the same reference plane, thereby improving the coaxiality of the motor. Additionally, grooves are provided on the bearings of the stator assembly, thereby increasing the bearing push-out force.

[0081] The second embodiment of this application will be described in detail below with reference to the accompanying drawings. Components that are the same as or similar to those in the first embodiment will not be described in detail here.

[0082] Figure 5 A perspective view of a brushless motor 200 according to a second embodiment of this application is shown. Unlike the four-pole, six-slot motor of Embodiment 1, this embodiment provides a six-pole, nine-slot motor configuration. Figure 6A and Figure 6B An exploded three-dimensional schematic diagram of the brushless motor 200 as viewed from both downward and upward angles is further shown. Figures 6A-7B As shown, the brushless motor 200 includes a stator assembly 210 and a rotor assembly 212. Furthermore, the motor 200 also includes coil windings 214, a cooling fan 216, bearings 218, a front cover / front bracket 219, etc. The coil windings 214 are wound on the stator assembly 210. The bearings 218 are held within the stator assembly 210. The cooling fan 216 is located near the bearings 218 and is used to guide cooling air above the stator coils and rotor to dissipate heat generated when current flows. The motor assembly also includes other components such as the coil winding wires and connecting wires, the rotor shaft, etc., which will not be described in detail here.

[0083] The stator assembly 210 further includes an outer stator subassembly 220 and an inner stator subassembly 230. For example... Figure 7A and 7B As shown, the outer stator sub-assembly 220, also known as the yoke, serves as the magnetic yoke of the motor. The yoke 220 is generally a cylindrical shape without top or bottom, with a roughly annular cross-section. Its inner wall is evenly spaced with multiple receiving grooves 222 to accommodate stator teeth. The receiving grooves 222 extend through both ends of the yoke 220 along the axial direction of the magnetic yoke 220. Groove ribs 226 are formed between the receiving grooves 222 and are spaced apart from each other. Parallel to the receiving grooves 222, the groove ribs 226 extend along the height direction of the yoke 220.

[0084] The main body 221 of the yoke 220 is formed by stacking several magnetic core laminations axially to form an outer stator lamination, and further has a 224 integrally formed therewith. When manufacturing the main body 221 of the yoke 220, several magnetic core laminations are stacked to form the cylindrical main body 221 of the yoke 220, and a support frame 224 is formed by injection molding plastic or rubber at local locations on the outer periphery of the main body 221. In one embodiment, the support frame 224 extends circumferentially about 1.5 slots along the outer periphery of the main body 221 of the yoke 220 and covers the area on the extended outer surface of the main body 221 of the yoke 220. Simultaneously, the support frame 224 has two legs 228 extending along a groove rib 226 on the inner periphery of the main body 221 of the yoke 220. The legs 228 connect the upper and lower parts of the support frame 224, locking the support frame 224 and the main body 221 of the yoke 220 together to form the outer stator subassembly 220. The main body 221 and the support frame 224 of the yoke 220 are formed as one piece. Unlike Embodiment 1, in Embodiment 1, the outer ring 132 and the inner shell 134 are cross-molded and the inner shell 134 is integrally coated with glue to the outer ring 132. In this embodiment, the support frame 224 is smaller in volume, occupies only a small area, and only partially coats the main body 221 with glue. Moreover, it mainly forms the exterior of the main body 221.

[0085] Figures 6A-6B The inner stator subassembly 230 is shown to include an inner stator lamination 250 and a winding frame 260. Further, as... Figure 8 As shown, the inner stator laminations 250 and the winding frame 260 are molded as a single unit. The winding frame 260 is made of insulating material, such as plastic or similar material, and serves as an insulator and support member for the inner stator laminations 250. The inner stator laminations 250 are made of laminated steel or steel sheet with a thickness of approximately 0.25 mm to minimize undesirable magnetic and electrical effects.

[0086] Figures 9A-9BThe inner stator lamination 250 is shown. As shown, the inner stator lamination 250 has a plurality of teeth 252 formed integrally. Unlike the four-pole, six-slot arrangement of Embodiment 1, this embodiment has nine teeth, thus forming a six-pole, nine-slot motor configuration. This allows for more efficient use of space and the arrangement of more coil windings. Furthermore, as... Figure 9B As shown, the teeth 252 are roughly I-shaped, with the upper end 258 being slightly longer than the lower end 259. The upper end 258 contacts the inner surface of the body 221 of the yoke 220 and is welded together by laser or other means. The lower ends 259 of these teeth 252 are interconnected by ribs 254, arranged roughly in a ring. See also Figure 9A The connecting portion between the teeth 252 is composed of several slender ribs 254. These ribs 254 are parallel to each other and spaced apart by a certain distance, forming a roughly rectangular opening 256 between adjacent ribs 254 and the teeth 252. It is understood that the opening 256 can also be any other shape such as a square or a circle. The opening 256 can effectively reduce magnetic leakage and improve motor performance. The ribs 254 are also formed by stacking stator laminations, which are connected together by stacking, welding, bonding, riveting or other means of ribbed thin metal plates to form an integral inner stator lamination 250.

[0087] Figures 10A-10B This is a three-dimensional diagram showing the lower and upper parts of the winding frame 260. Figure 10C This is a top view of the winding frame 260. As shown, the winding frame 260 has a generally cylindrical body 262 and multiple winding units 264. The multiple winding units 264 are arranged radially around the outer periphery of the body 262. The winding units 264 extend from the body 262, forming a T-shape, for placing the coil windings. Adjacent winding units 264 are spaced apart from each other. The winding unit 264 has a through slot 265 for receiving teeth 252. The length direction of the slot 265 is perpendicular to the central axis of the cylindrical body 262. The slot 265 forms a channel through the body 262 and the winding units 264. The outer periphery of the end of the winding unit 264 away from the body 262 is formed into a flange 266. The portion between the flange 266 and the body 262 is used to place the coil windings 214, thereby effectively fixing the coil windings. The top of the flange 266 is formed into a track shape to receive the upper end 258 of the tooth 252 and expose it to the outside, so that it is received in the receiving groove 222 on the inner surface of the yoke 220 and fits against the inner surface to be welded together by laser or other means. Figure 11A-11B A stator assembly with windings is shown. The motor assembly according to the above embodiment is more convenient for winding and assembly, and allows for the arrangement of more winding coils, resulting in a significant increase in slot fill factor.

[0088] In addition, such as Figures 10A-10C As shown, the lower end 267 of the winding frame 260 is a hollow ring molded integrally with the main body, serving as a rear support. Therefore, the entire nail assembly does not require an additional separate rear support assembly, saving space and making the overall structure more compact. Furthermore, by reducing the number of parts, embodiments of this application also save costs.

[0089] Furthermore, in this embodiment, the bearing 218 can also be molded integrally with the winding frame 260, such as... Figure 11B As shown. In the motor structure of this embodiment, the bearings can be secured more tightly, resulting in a more compact and robust overall structure, and a simpler assembly process, making it easier for the user to operate. The coil wires are connected to conductive contacts on the support frame 224 of the yoke 220.

[0090] In addition, such as Figure 12 As shown, a groove 301 is provided in the middle of the bearing 218, which can increase the bearing push force and further reduce the size of the motor. The bearing 218 can be molded into the winding frame 260 by means of the groove 301.

[0091] In summary, the structure of this application adopts an integrated design, tightly combining the winding frame 260, bearing 218, and inner stator laminations 250 through a rubber coating process to form a single integral component, eliminating the need for a rear support. Simultaneously, to simplify the installation of the front cover / front support 219, the winding frame 260 has multiple outwardly extending protrusions on its end face facing the front cover 219, while the front cover 219 has multiple grooves that mate with these protrusions. The ends of the protrusions are T-shaped, and the front cover 219 has two pin holes corresponding to the bottom of the grooves. When the protrusions mate with the grooves, pins 281 connect the front cover / front support 219 to the inner stator sub-assembly 230. This design not only reduces the number of parts but also ensures precise alignment between components through a single reference, facilitating assembly and improving the coaxiality of the motor.

[0092] The embodiments of this application not only significantly simplify the assembly process, reduce assembly difficulty and error rate, and significantly improve slot fill rate, but also effectively improve the coaxiality of the motor, thereby enhancing overall performance and stability. This structural design is particularly suitable for applications requiring high precision and assembly efficiency, and can meet the needs of modern industry for efficient production and high-quality products.

[0093] The exemplary stator assembly, electric motor, power tool, and manufacturing method described herein advantageously provide an electric motor that is smaller, more efficient, and has a higher slot fill rate compared to conventional prior art electric motors.

[0094] The features disclosed herein can reduce manufacturing costs and reduce the time required to wind stator coils due to fewer components and faster winding enabled by radially outward protrusions in the inner stator sub-assemblies.

[0095] The above embodiments have been described by way of example only. Many variations can be made without departing from the scope of this application as defined in the appended claims.

[0096] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, system embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0097] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0098] Although this application has been described in detail with reference to certain preferred embodiments, variations and modifications as described and defined in the appended claims exist within the spirit and scope of this application.

Claims

1. A stator assembly for a brushless motor, the brushless motor having an internal rotor that rotates about an axis, the stator assembly comprising: The outer stator sub-assembly has a ring-shaped component; An inner stator sub-assembly, which is housed within and fixedly attached to the outer stator sub-assembly, the inner stator sub-assembly comprising: A frame having an annular body and a plurality of protrusions extending outward from the annular body for supporting coils surrounding thereon; One-piece molded shell, The shell and the frame are molded as a single unit; The protrusion protrudes from the housing to contact the annular part of the outer stator subassembly.

2. The stator assembly of claim 1, wherein the plurality of protrusions comprises a plurality of teeth extending radially outward from the periphery of the annular body of the frame and spaced apart from each other.

3. The stator assembly of claim 2, wherein the frame is formed by riveting and stacking a plurality of ribbed and unribbed chips to form a plurality of holes between the teeth on the annular body.

4. The stator assembly of claim 2, wherein the frame is composed of laminated metal or sheet metal.

5. The stator assembly according to any of the preceding claims, wherein the annular member has a support member at least partially molded thereon, the support member and the housing of the inner stator sub-assembly being made of an insulating material.

6. The stator assembly according to any one of the preceding claims, wherein the inner stator subassembly and the outer stator subassembly are fixedly connected at a plurality of locations where the protrusion contacts the annular member by laser welding or ultrasonic welding.

7. The stator assembly according to any one of claims 2-6, wherein the coil of the inner stator subassembly is wound by a machine operating outside the annular body of the inner stator subassembly.

8. The stator assembly according to any one of claims 2-6, wherein the ratio of the cross-sectional area of ​​the coil conductor of the tooth to the total usable area of ​​the coil of the tooth is on average between 45% and 55%.

9. The stator assembly according to any of the preceding claims, wherein the inner stator subassembly further includes a bearing for supporting a shaft molded therein, wherein the bearing is received in a groove on an end face of the housing.

10. The stator assembly according to any of the preceding claims, wherein the front end cover of the motor is connected to the stator assembly by a pin and uses the same reference surface.

11. A brushless motor, comprising: Stator assembly according to any one of claims 1-9; The rotor assembly, one end of which is supported on a bearing of the inner stator subassembly, is substantially enclosed by its shaft to the frame of the stator assembly, wherein the rotor assembly includes a sheath molded around it.

12. The brushless motor according to claim 11 further includes a cooling fan and at least three control lines electrically connected to the stator coils.

13. An electric tool comprising a brushless motor having a stator according to any one of claims 1-10.

14. A power tool comprising a brushless motor according to claim 11 or 12.

15. A method for manufacturing a stator assembly, comprising: The support is at least partially molded onto the annular member to form the outer stator subassembly; The housing is molded onto the bearing and frame to form the inner stator sub-assembly; The frame has multiple teeth extending radially outward from the annular body; Arrange the coil windings on the housing at positions corresponding to the teeth; The inner stator sub-assembly is housed within the outer stator sub-assembly and welded together.

16. The method of manufacturing a stator assembly according to claim 15, wherein a coil is formed on each tooth by winding wire from outside the frame of the inner stator sub-assembly.

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