Motor stator, motor and manufacturing method of motor stator

Abstract

The invention discloses a motor stator, a motor and a manufacturing method of the motor stator, and the motor stator comprises a stator yoke part iron core which comprises stator yoke part iron core units which are arranged in a segmented manner, the stator yoke part iron core units extend from a first end to a second end, the first end is provided with a positioning boss, the second end is provided with a positioning groove, and the positioning boss is arranged in the positioning groove; the stator yoke iron core units are connected end to end to form a closed ring, and each stator yoke iron core unit is provided with a plurality of positioning clamping grooves. The stator tooth part iron core comprises stator tooth part iron core units which are arranged in sections, each stator tooth part iron core unit comprises a plurality of positioning convex teeth, and the radial outer ends of the positioning convex teeth are provided with positioning clamping teeth; the coil is formed by winding a flat wire, and the positioning convex teeth are sleeved with the coil; wherein the positioning clamping teeth are assembled in the positioning clamping grooves, the stator tooth part iron core units form a closed ring, and the closed groove motor is formed through the connecting ribs. The problems of performance defects of large torque fluctuation, large rotating speed fluctuation, large cogging torque and the like of a traditional open slot motor are fundamentally solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric machines, and in particular to an electric machine stator, an electric machine and a method for manufacturing an electric machine stator. BACKGROUND

[0002] Torque motors are widely used in four-axis, five-axis rotary tables and swing heads, swing tables and other high-precision motion occasions of numerical control machine tools, and are required to have high running accuracy, especially good low-speed stability, which is specifically manifested in the requirements of low cogging torque, small torque fluctuation, small speed fluctuation, high continuous torque, strong overload capacity, fast response speed, strong servo rigidity, wide load adaptability, etc.

[0003] Torque motors generally operate at low speed, so they generally have a high number of poles, which provides the prerequisite for designing the number of stator slots and the number of rotor poles to be close, i.e., it is easy to design in the form of concentrated winding. In addition, the winding ends of concentrated winding are short, which can effectively shorten the volume of the motor and thus reduce the weight of the motor. Therefore, concentrated winding is widely used in the field of low-speed torque motors.

[0004] In recent years, there has been a growing demand for improving the efficiency of electric machines and increasing the power density and torque density of electric machines, which has put new requirements on the conductor space factor in the stator slot. Traditional low-speed concentrated winding motors are generally wound with round wires. When round wires are arranged next to each other, there is a large gap between the outer circles. Compared to round wires, flat wires have a smaller space occupied when arranged due to their shape characteristics. Therefore, the same winding slot space can accommodate flat wires with a larger cross section. Therefore, electric machines with flat wire conductors have become a research hotspot in the field of electric machines due to their excellent characteristics, especially in the field of new energy vehicle drive motors, where the penetration rate of flat wire motors exceeds 90%. However, the bending strength of flat wires is much higher than that of round wires composed of multiple wires with the same cross-sectional area, so flat wires cannot be wound on the core as easily as round wires.

[0005] Existing technologies related to flat wire distributed winding, such as in the field of new energy vehicles (patent number US2022407378A1), involve preforming flat wires into a shape similar to a U-shaped hairpin, then inserting the hairpin flat wires from one end of the core slot, bending the ends of the hairpin conductors, and finally welding all adjacent end points to form individual coil windings. This method is very complex, and due to the presence of a large number of welding points, the reliability is low, the quality is difficult to control, the production line investment cost is high, the degree of flexibility of the production line is low, and the difficulty of product change production is very high, making it suitable for automatic production of products with single specifications and large order quantities.

[0006] The prior art related to the flat wire concentrated winding, such as patent number CN117997010A, designs the stator into a separated structure, pre-winds the flat wire conductor into a shape, then fits into the separated stator, and finally combines into a complete stator. This method has a complex structure, poor processability, poor overall size accuracy of the stator, and the separated stator tooth slot structure greatly affects the motor magnetic circuit, directly increases the motor core loss and reduces the power density of the motor, especially the poor manufacturing consistency, which ultimately leads to the disadvantage of large fluctuation of motor performance. In addition, such as patent number CN101657953A, the coil is first formed and then fitted on the teeth of the stator core. In this way, welding of the same column of coils is not required, thereby reducing the welding points. However, the teeth of the stator core are trapezoidal teeth, and the slots of the stator core are rectangular slots. Therefore, the cross section of the corresponding coil is also trapezoidal, that is, the size of the inner coil frame is large, and the size of the outer coil frame is small. The starting point of designing the teeth of the stator core as trapezoidal teeth is to avoid the occurrence of gaps in the stator slots, which affects the heat dissipation efficiency of the motor. However, such design causes great difficulty in manufacturing flat wire coils, and when embedding coils between adjacent two groups of coils, the coil on one side needs to be placed by extruding and deforming, and then the coil on the other side needs to be placed by extruding and deforming. This installation method can only be applied to relatively soft flat wires, and there are problems in installing coils made of flat wires with large cross-sectional size and high rigidity. In addition, the two columns of coils in the same slot are close to each other due to the limited contact area with the stator core, thereby causing poor heat dissipation performance of the motor. In addition, this scheme is an open slot motor, and motor theory shows that the open slot motor naturally has many disadvantages such as large torque fluctuation, large speed fluctuation, and large cogging torque. This scheme ignores these problems, but the above disadvantages are the direct restricting factors for the operation of such motors in high-precision environments.

[0007] In summary, how to retain the high space factor characteristics of flat wire winding, realize the manufacturability of flat wire winding and supporting core, and solve the performance defects of the existing separated stator core flat motor such as large torque fluctuation, large speed fluctuation, and large cogging torque have become urgent problems in the industry. SUMMARY

[0008] The purpose of the present application is to at least solve one of the technical problems existing in the prior art, and provide a motor stator, a motor and a manufacturing method of a motor stator.

[0009] The technical scheme adopted by the present application to solve its technical problems is: In a first aspect, a motor stator comprises: The stator yoke core includes stator yoke core units arranged in sections, the stator yoke core units are in the shape of a circular arc, the stator yoke core units extend from a first end to a second end along the length direction of the circular arc, the first end is provided with a positioning boss, the second end is provided with a positioning recess corresponding to the positioning boss, a plurality of the stator yoke core units are connected head to tail to form a closed ring through the positioning boss and the positioning recess, and the radial inner wall surface of the stator yoke core unit is provided with a plurality of positioning clamping grooves, which are distributed at intervals along the length direction of the circular arc; The stator tooth core includes stator tooth core units arranged in sections, the stator tooth core units include a plurality of positioning protruding teeth extending in the radial direction, the radial outer end of the plurality of positioning protruding teeth is provided with a positioning clamping tooth, and the radial inner end of the plurality of positioning protruding teeth is connected through a connecting rib, so that the stator tooth core unit is in the shape of a continuously extending circular arc; The coil is wound by using a flat wire, and the coil is sleeved on the positioning protruding tooth. The positioning clamping tooth of the stator tooth core unit is assembled in the positioning clamping groove of the stator yoke core unit, a plurality of the stator tooth core units form a closed ring on the radial inner side of the stator yoke core, and a closed slot motor is formed through the connecting rib.

[0010] In combination with the first aspect, in some implementations of the first aspect, the end surface extension line of the first end of the stator yoke core unit points to the center of the stator yoke core, the end surface extension line of the second end of the stator yoke core unit points to the center of the stator yoke core, the positioning boss protrudes outward from the end surface of the first end, and the positioning recess is recessed inward from the end surface of the second end.

[0011] In combination with the first aspect and the above implementations, in some implementations of the first aspect, the positioning clamping groove extends from the radial inner wall surface to the outer wall surface of the stator yoke core unit and is cut off before extending to the outer wall surface, the positioning clamping groove is in the shape of a narrowing, the neck part of the positioning clamping tooth is narrowed, the positioning clamping tooth is assembled in the positioning clamping groove in the axial direction and clamped in the positioning clamping groove in the radial direction.

[0012] In combination with the first aspect and the above implementations, in some implementations of the first aspect, the positioning clamping tooth is provided with wings extending to both sides in the circumferential direction on the radial outer side of the neck part, and the positioning clamping groove is provided with wing clamping grooves matched with the wings.

[0013] In combination with the first aspect and the above implementations, in some implementations of the first aspect, the splicing position of adjacent stator yoke core units in the circumferential direction is staggered with the splicing position of adjacent stator tooth core units in the circumferential direction.

[0014] In some implementation forms of the first aspect, in combination with the first aspect and the above implementation forms, the stator yoke core unit comprises a plurality of silicon steel sheets stacked in the axial direction by a certain height, and the stator tooth core unit comprises a plurality of silicon steel sheets stacked in the axial direction by a certain height.

[0015] In some implementation forms of the first aspect, in combination with the first aspect and the above implementation forms, the positioning protrusions are straight cylinders extending in the radial direction with equal cross sections, and the coils are straight hollow helical coils.

[0016] In some implementation forms of the first aspect, in combination with the first aspect and the above implementation forms, the coils of adjacent positioning protrusions are separately wound or continuously wound.

[0017] The second aspect discloses a motor comprising the motor stator according to any one of the implementation forms of the first aspect.

[0018] The third aspect discloses a manufacturing method of the motor stator according to any one of the above aspects, comprising the following steps: Preparation of the stator yoke core unit, the stator tooth core unit and the coils according to the demand; Sleeving of the coils on the positioning protrusions of the stator tooth core unit; Mispositioning sleeve assembly of the stator tooth core unit with the coils and the stator yoke core unit, and axial assembly of the positioning notches of the stator tooth core unit in the positioning grooves of the stator yoke core unit. The technical scheme has at least one of the following advantages or beneficial effects: In the technical scheme of the present application, the segmented stator yoke core unit and the segmented stator tooth core unit are arranged in the circumferential direction in a uniformly distributed manner to form a mortise-tenon structure sleeve assembly of the stator core as a whole through the double cooperation between the positioning protrusions and the positioning grooves, the positioning notches and the positioning protrusions, and a stable support structure is formed, which can greatly improve the overall rigidity of the stator core, solve a series of problems such as excessive assembly gap of the block assembly type motor, resulting in large additional vibration, high noise, insufficient servo rigidity, and decreased load capacity, etc. At the same time, the connecting ribs of the stator tooth core form the characteristics of a closed slot motor, which fundamentally solves the performance defects of the traditional open slot motor such as large torque fluctuation, large speed fluctuation, and large slot torque. In addition, the flat wire coil wound by the flat wire material is used, which fully utilizes the high copper filling rate of the flat wire material to achieve high motor power density and high torque density. Moreover, the regular flat wire coil further reduces the thermal resistance in the motor, so that the heat in the motor can be quickly dissipated, and the continuous working capacity of the motor is further improved.

[0019] Additional aspects and advantages of the present application will be made apparent from the following description of embodiments of the application, which is given for purposes of illustration and not limitation. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description of embodiments of the present application, taken in conjunction with the accompanying drawings. Figure 1 is a structural schematic diagram of a stator of an embodiment of the present application; Figure 2 is a structural schematic diagram of a stator yoke core unit of an embodiment of the present application; Figure 3 is a structural schematic diagram of a stator tooth core unit of an embodiment of the present application; Figure 4 is a structural schematic diagram of a stator yoke core unit and a stator tooth core unit of an embodiment of the present application; Figure 5 is a structural schematic diagram of a stator yoke core unit and a stator tooth core unit of an embodiment of the present application; Figure 6 is a structural schematic diagram of a single-wound coil of an embodiment of the present application; Figure 7 is a side view of a single-wound coil of an embodiment of the present application; Figure 8 is a structural schematic diagram of a continuous-wound coil of an embodiment of the present application. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present application, the preferred embodiments of the present application are shown in the accompanying drawings, the role of the drawings is to supplement the description of the text part of the description, so that people can intuitively and visually understand each technical feature and the overall technical solution of the present application, but it cannot be understood as a limitation on the scope of protection of the present application.

[0022] In the present application, if the direction (up, down, left, right, front and back) is described, it is only for the convenience of describing the technical scheme of the present application, and is not indicative or suggestive of the technical features indicated must have a specific orientation, be constructed and operated in a specific orientation, therefore, cannot be understood as a limitation on the present application.

[0023] In this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number. In the description of this invention, the terms "first" and "second" are used only to distinguish technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0024] In this invention, unless otherwise explicitly defined, the terms "setting," "installing," and "connecting" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium; a fixed connection, a detachable connection, or an integrally formed connection; a mechanical connection, an electrical connection, or a connection capable of mutual communication; or the internal connection of two components or the interaction between two components. Those skilled in the art can reasonably determine the specific meaning of the above terms in this invention based on the specific content of the technical solution.

[0025] See Figures 1-7 An embodiment of the present invention provides a motor stator, including a stator yoke core 100, a stator tooth core 200, and a coil 300. The stator yoke core 100 includes segmented stator yoke core units 101, the lengths of which may be the same or different. Each stator yoke core unit 101 is arc-shaped and extends from a first end 102 to a second end 103 along the length of the arc. The first end 102 is provided with a positioning boss 104, and the second end 103 corresponds to the positioning boss. 104 is provided with a positioning groove 105. In other words, the positioning boss 104 at the first end 102 and the positioning groove 105 at the second end 103 are positioned and shaped in a corresponding manner, so that multiple stator yoke core units 101 are connected end to end through the positioning boss 104 and the positioning groove 105 to form a closed loop. The radial inner wall surface of the stator yoke core unit 101 is provided with multiple positioning slots 106. The positioning slots 106 are used to connect with the inner stator tooth core 200. The multiple positioning slots 106 are distributed at intervals along the length direction of the arc.

[0026] The stator tooth core 200 includes segmented stator tooth core units 201. Each stator tooth core unit 201 includes multiple radially extending positioning protrusions 202. The radially outer ends of the multiple positioning protrusions 202 are provided with positioning retaining teeth 203. The radially inner ends of the multiple positioning protrusions 202 are connected by connecting ribs 204, so that the stator tooth core unit 201 is in a continuously extending arc shape.

[0027] The coil 300 is made of flat wire, such as flat copper wire, and is fitted onto the positioning protrusion 202.

[0028] Wherein, the positioning clamping teeth 203 of the stator tooth core unit 201 is assembled in the positioning clamping groove 106 of the stator yoke core unit 101, a plurality of stator tooth core units 201 form a closed ring on the radial inner side of the stator yoke core 100, and the stator yoke core 100 and the stator tooth core 200 form the inner ring and the outer ring of the motor stator respectively, and form a closed slot motor through the connecting ribs 204. In other words, the inner circumferential surface of the stator tooth core 200 is a continuous surface without open slot.

[0029] In the technical scheme of the present application, the segmented stator yoke core unit 101 and the segmented stator tooth core unit 201 are arranged along the circumference and form a mortise-tenon structure set-together stator core whole through the double cooperation between the positioning boss 104 and the positioning groove 105, the positioning clamping groove 106 and the positioning clamping teeth 202, and form a stable support structure, which can greatly improve the overall rigidity of the stator core, and solve a series of problems such as excessive assembly gap, large vibration, high noise, insufficient servo rigidity, and decreased load capacity of the motor caused by the assembly gap of the split assembly type motor. At the same time, the connecting ribs 204 of the stator tooth core 200 form the characteristics of the closed slot motor, which fundamentally solves the performance defects of the traditional open slot motor such as large torque fluctuation, large speed fluctuation, and large slot torque. In addition, by matching the flat wire coil 300 wound by flat wire, the high motor power density and high torque density brought by the high copper filling rate of the flat wire are fully utilized. Moreover, the regular flat wire coil 300 further reduces the thermal resistance in the motor, allowing the heat in the motor to be quickly dissipated, and further improving the continuous working capacity of the motor.

[0030] In other words, the embodiment of the present application uniformly splits the stator core of the traditional whole structure of the stator yoke and the stator tooth into the segmented stator yoke core unit 101 and the segmented stator tooth core unit 201 along the circumference, the segmented stator yoke core unit 101 and the segmented stator tooth core unit 201 contain a plurality of stator unit slots, and the segmented stator yoke core unit 101 and the segmented stator tooth core unit 201 are designed in a mortise-tenon structure, so that they can be set together into a stable whole along the circumference. On the one hand, the stator yoke core 100 and the stator tooth core 200 of the stator can be independently manufactured, thereby solving the problem of waste of raw materials of the moment motor stator core in the form of large hollow, and being very suitable for mass production by open stamping die; on the other hand, the mortise-tenon structure of the segmented and separated stator yoke core unit 101 and the stator tooth core unit 201 can be set together into a circumferential whole, thereby forming a closed slot structure stator core, and further solving the performance defects of the existing split open slot stator core flat line motor such as large torque fluctuation, large speed fluctuation, and large slot torque.

[0031] In some embodiments, see Figure 2 , Figure 5 The extended end face of the first end 102 of the stator yoke core unit 101 points to the center of the stator yoke core 100, and the extended end face of the second end 103 of the stator yoke core unit 101 also points to the center of the stator yoke core 100. A positioning boss 104 protrudes outward from the end face of the first end 102, and a positioning groove 105 is recessed inward from the end face of the second end 103. Multiple stator yoke core units 101 can be connected end-to-end to form a complete circular stator yoke core 100. This ensures both ease of assembly and the overall precision and stability of the entire stator yoke core 100, making it ideal for mass production using stamping dies. In some embodiments, see Figure 2 , Figure 3 , Figure 4 The positioning groove 106 extends from the radial inner wall of the stator yoke core unit 101 towards the outer wall and terminates before reaching the outer wall. The positioning groove 106 is tapered, and the neck of the positioning tooth 203 narrows. The positioning tooth 203 is axially fitted into the positioning groove 106 and radially locked into it. The stator tooth core unit 201 and the stator yoke core unit 101 form a radial tenon and mortise through the engagement of the positioning tooth 203 and the positioning groove 106, thus forming a stable integral structure between the stator yoke core 100 and the stator tooth core 200.

[0032] In some embodiments, see Figure 2 , Figure 3 , Figure 4 The positioning tooth 203 has a wing 205 extending circumferentially to both sides on the radial outer side of the neck, and the positioning groove 106 has a wing groove 107 that cooperates with the wing.

[0033] It is understandable that, in addition to the wing-and-wing-and-slot mating method, the positioning tooth 203 and the positioning slot 106 can also be configured with an assembly structure such as a dovetail groove, so that the stator yoke core 100 and the stator tooth core 200 form a stable whole with radial tenon and mortise.

[0034] The embodiments of the present invention, through the double-positioning mortise and tenon structure, enable it to be fitted together as a stable whole along the circumference, solving a series of problems caused by the large fitting gaps of segmented modular motors, such as additional vibration, noise, insufficient servo rigidity, and reduced load capacity.

[0035] In some embodiments, see Figure 4 , Figure 5The splicing position of the adjacent stator yoke core unit 101 in the circumferential direction is staggered with the splicing position of the adjacent stator tooth core unit 201 in the circumferential direction, so as to ensure the stability of the integrated structure of the stator yoke core 100 and the stator tooth core 200.

[0036] In some embodiments, the stator yoke core unit 101 comprises a plurality of silicon steel sheets stacked in the axial direction by a certain height, and the stator tooth core unit 201 comprises a plurality of silicon steel sheets stacked in the axial direction by a certain height.

[0037] In some embodiments, referring to Figure 1 、 Figure 5 、 Figure 6 The positioning convex tooth 202 is in a straight cylinder shape extending in the radial direction, and the coil 300 is a straight cylinder hollow spiral coil 300.

[0038] In some embodiments, referring to Figure 6 、 Figure 7 、 Figure 8 The coils 300 of the adjacent positioning convex teeth 202 are separately wound or continuously wound, and the continuously wound coil 300 can improve the reliability of the motor operation.

[0039] The embodiments of the present application also provide a motor comprising the motor stator and the rotor in any of the above embodiments.

[0040] The embodiments of the present application also provide a manufacturing method of the motor stator in the above embodiments, comprising the following steps: Preparation of the stator yoke core unit 101, the stator tooth core unit 201 and the coil 300 according to the required quantity; Sleeving the coil 300 on the positioning convex tooth 202 of the stator tooth core unit 201; The stator tooth core unit 201 with the coil 300 and the stator yoke core unit 101 are assembled in a staggered manner, and the positioning clamping teeth 203 of the stator tooth core unit 201 are assembled in the axial direction in the positioning recesses 105 of the stator yoke core unit 101; Finally, according to the motor principle and winding design drawing, the wiring work between the equal-width straight-cylinder hollow spiral flat wire coils 300 can be completed, thus forming an ultra-high-precision high-torque density torque motor solution with closed slot characteristics, good manufacturability and high-torque density of the flat wire coil 300.

[0041] In the description of the present specification, the description referring to the terms "example", "embodiment" or "some embodiments" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0042] Of course, the present application is not limited to the above-mentioned embodiments, and those skilled in the art can make equivalent modifications or replacements without departing from the spirit of the present application, and these equivalent modifications or replacements are included in the scope defined by the claims of the present application.

Claims

1. A motor stator, characterized in that, include: The stator yoke core includes segmented stator yoke core units, each stator yoke core unit being arc-shaped. Each stator yoke core unit extends from a first end to a second end along the length of the arc. The first end is provided with a positioning boss, and the second end is provided with a positioning groove corresponding to the positioning boss. Multiple stator yoke core units are connected end-to-end through the positioning boss and the positioning groove to form a closed loop. The radial inner wall surface of each stator yoke core unit is provided with multiple positioning slots, which are spaced apart along the length of the arc. The stator tooth core includes segmented stator tooth core units. Each stator tooth core unit includes multiple radially extending positioning protrusions. The radially outer ends of the multiple positioning protrusions are provided with positioning retaining teeth. The radially inner ends of the multiple positioning protrusions are connected by connecting ribs, so that the stator tooth core unit is in a continuously extending arc shape. The coil is made of flat wire wound together and is sleeved on the positioning protrusion. The positioning teeth of the stator tooth core unit are assembled into the positioning slots of the stator yoke core unit. Multiple stator tooth core units form a closed ring on the radial inner side of the stator yoke core and form a closed slot motor through the connecting ribs.

2. The motor stator according to claim 1, characterized in that, The extension line of the end face of the first end of the stator yoke core unit points to the center of the stator yoke core, and the extension line of the end face of the second end of the stator yoke core unit points to the center of the stator yoke core. The positioning boss protrudes outward from the end face of the first end, and the positioning groove is recessed into the end face of the second end.

3. The motor stator according to claim 1, characterized in that, The positioning slot extends from the radial inner wall of the stator yoke core unit towards the outer wall and terminates before reaching the outer wall. The positioning slot is constricted, and the neck of the positioning tooth is narrowed. The positioning tooth is axially fitted into the positioning slot and radially clamped into the positioning slot.

4. The motor stator according to claim 3, characterized in that, The positioning teeth are provided with wings extending circumferentially to both sides on the radially outer side of the neck, and the positioning slot is provided with a wing slot that cooperates with the wings.

5. The motor stator according to claim 1, characterized in that, The circumferential splicing positions of adjacent stator yoke core units are staggered from the circumferential splicing positions of adjacent stator tooth core units.

6. The motor stator according to claim 1, characterized in that, The stator yoke core unit includes multiple silicon steel sheets stacked along the axial direction to a certain height, and the stator tooth core unit includes multiple silicon steel sheets stacked along the axial direction to a certain height.

7. The motor stator according to claim 1, characterized in that, The positioning protrusion is a straight cylindrical shape extending radially with a uniform cross section, and the coil is a straight cylindrical hollow spiral coil.

8. The motor stator according to claim 1, characterized in that, The coils of adjacent positioning teeth are wound individually or continuously.

9. An electric motor, characterized in that, The motor stator includes any one of claims 1 to 8.

10. A method for manufacturing a motor stator as described in any one of claims 1 to 8, characterized in that, Includes the following steps: Prepare the stator yoke core unit, the stator tooth core unit, and the coil according to the required quantities; The coil is fitted onto the positioning teeth of the stator tooth core unit; The stator tooth core unit with coil and the stator yoke core unit are assembled in a staggered fit, and the positioning teeth of the stator tooth core unit are axially fitted into the positioning groove of the stator yoke core unit.

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