A split type motor stator core with low cogging torque

Abstract

This invention discloses a segmented motor stator core with low cogging torque, relating to the field of motor technology. It includes single stator core modules, with the segmented motor stator core composed of several groups of these modules assembled into a ring. Through a sawtooth structure, the magnetic field transition interface formed after the splicing of adjacent single stator core modules exhibits a non-linear, smooth, and gradual change, effectively weakening abrupt changes in magnetic reluctance and making the air gap magnetic field distribution closer to a sine wave. This significantly reduces cogging torque, directly improving the vibration and noise levels during motor operation. Furthermore, the precise semi-circular concave-convex positioning structure at the yoke ensures the accuracy and tightness of the splicing between single stator core modules, guaranteeing the continuity of the magnetic circuit, reducing magnetic leakage, and maintaining the high efficiency of the motor. Simultaneously, a dedicated process positioning groove on the outer diameter of the module provides a stable and reliable clamping reference for the winding process, greatly improving winding efficiency and consistency.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a segmented motor stator core with low cogging torque. Background Technology

[0002] An electric motor is an electromagnetic device that converts electrical energy into mechanical energy (electric motor) or mechanical energy into electrical energy (generator). It is one of the most fundamental power sources in modern industry and daily life. Electric motors come in many varieties, but are mainly classified into electric motors and generators based on the direction of energy conversion. As a "bridge between electrical and mechanical energy," the technological advancement of electric motors has driven the Industrial Revolution and the development of modern technology. From early DC motors to today's intelligent servo systems, electric motors have consistently made breakthroughs in energy efficiency, precision, and control flexibility, continuously empowering countless industries.

[0003] The stator core is the core magnetic component of the stator (the stationary part of the motor). Located inside the stator windings, its main function is to form part of the motor's main magnetic circuit, guiding the magnetic field generated by the stator windings (or external magnetic fields) through it, while also supporting and fixing the stator windings. Its performance directly affects the motor's magnetic circuit efficiency, losses, temperature rise, and overall operational stability, making it a crucial element in motor design.

[0004] A segmented stator core refers to a stator core that is divided into several independent sector-shaped blocks (or arc-shaped blocks) along the circumference. Each block contains part of the teeth, yoke, and stator slots, and is then assembled into a complete cylindrical magnetic circuit through mechanical splicing (such as bolting, welding, or bonding). It is a commonly used core structure in large motors (especially high-power, large-diameter motors), and its core purpose is to solve the limitations of integral cores in manufacturing, transportation, and assembly.

[0005] Based on existing technology, most existing modular stator cores have a simple structure, typically using single-tooth or multi-tooth modular splicing structures. Their advantages include ease of winding and improved slot fill factor, but they also have the following drawbacks:

[0006] 1. Cogging torque effect: There is usually a significant slot width between the rotor teeth. When the rotor permanent magnet rotates, the magnetic field changes drastically, which can easily generate a large cogging torque, resulting in increased noise and vibration during motor operation.

[0007] 2. Low splicing positioning accuracy: Most segmented iron cores use a simple concave-convex structure for positioning, resulting in large gaps after splicing, which can easily lead to discontinuity in the magnetic circuit and increased magnetic leakage.

[0008] 3. Poor winding processability: Some segmented iron cores lack dedicated process positioning structures, making it inconvenient to install winding clamps, which affects winding efficiency and consistency.

[0009] Therefore, this invention proposes a segmented motor stator core with low cogging torque to solve the problems existing in the prior art. Summary of the Invention

[0010] To address the aforementioned problems, the present invention aims to propose a segmented motor stator core with low cogging torque. By optimizing the tooth serration structure and positioning structure of each segment of the core, the rotor magnetic field change is made closer to a sine wave. While maintaining motor performance, this invention improves the noise and vibration problems caused by cogging torque, and also enhances the splicing accuracy and winding processability of the segmented core.

[0011] To achieve the objective of this invention, the invention is implemented through the following technical solution: a segmented motor stator core with low cogging torque, comprising a single stator core module, wherein the segmented motor stator core is composed of several groups of the single stator core modules spliced ​​into a ring-shaped integral structure, the single stator core module being composed of several groups of electrical steel sheets, and the single stator core module comprising an integrally formed yoke, teeth, and tooth tip, wherein the teeth are located between the yoke and the tooth tip;

[0012] The left and right sides of the tooth tip form serrated structures that extend axially, and the serrated grooves and serrated tips of the serrated structures on the left and right sides of the tooth tip are staggered and oppositely distributed in the axial direction.

[0013] When adjacent stator core modules are spliced ​​together, the serrations on one set of tooth tips are arranged opposite to the serrations on the adjacent tooth tips in the circumferential direction and form a top-top overlap.

[0014] A further improvement is that the width of the groove is equal to the width of the top of the sawtooth.

[0015] A further improvement is that: a semi-circular groove and a semi-circular boss are respectively provided on both sides of the yoke, and the semi-circular groove and the semi-circular boss are adapted to each other.

[0016] A further improvement is that: at least one process positioning groove is provided on the outer circumferential surface of the yoke corresponding to the central axis of the tooth, and the process positioning groove cooperates with the positioning protrusion on the winding fixture.

[0017] A further improvement is that the cross-sectional shape of the process positioning groove is selected from one of a rectangle, a V-shape, or a semi-circle.

[0018] A further improvement is that the inner side of the single stator core module is covered with an insulating layer, which is injection molded onto the outer side of the teeth and the opposite side of the yoke and the tooth tip.

[0019] A further improvement is that the single stator core module is formed by stacking several sets of electrical steel sheets and fixing them together by riveting.

[0020] The beneficial effects of this invention are as follows: Through a "top-to-top coincidence" sawtooth structure, the magnetic field transition interface formed after the splicing of adjacent stator core modules is non-linear and smoothly gradual, effectively weakening the abrupt change in magnetic reluctance and making the air gap magnetic field distribution closer to a sine wave. This significantly reduces cogging torque and directly improves the vibration and noise levels during motor operation. Furthermore, the precise semi-circular concave-convex positioning structure at the yoke ensures the accuracy and tightness of the splicing between stator core modules, guaranteeing the continuity of the magnetic circuit, reducing magnetic leakage, and maintaining the high efficiency of the motor. Simultaneously, the dedicated process positioning groove on the outer diameter of the module provides a stable and reliable clamping reference for the winding process, greatly improving winding efficiency and consistency. In addition, the modular design combined with the insulation coating process balances production convenience and reliability, thus simultaneously achieving electromagnetic performance optimization and simplifying the production process without significantly increasing costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the three-dimensional structure of the segmented motor stator core of the present invention;

[0022] Figure 2 This is a three-dimensional structural diagram of the single stator core module of the present invention;

[0023] Figure 3 This is a schematic diagram of the splicing of adjacent single stator core modules according to the present invention.

[0024] Among them: 1. Single stator core module; 101. Yoke; 1011. Semicircular groove; 1012. Semicircular boss; 1013. Process positioning groove; 102. Tooth; 103. Tooth tip; 1030. Sawtooth structure; 1031. Sawtooth groove; 1032. Sawtooth tip; 2. Electrical steel sheet; 3. Insulation layer. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that the technical means not described in detail in the following embodiments are all conventional means in the art, are not the key points of the invention, and will not be elaborated upon.

[0027] Example 1

[0028] according to Figure 1 , Figure 2 , Figure 3As shown, this embodiment provides a segmented motor stator core with low cogging torque. It adopts a segmented structure, the core of which is formed by splicing twelve independent single stator core modules 1 end to end to form a complete ring stator. Each single stator core module 1 is an independent electromagnetic unit. The main body of the single stator core module 1 is formed by stacking several sets of electrical steel sheets 2 along the axial direction (the electrical steel sheets 2 in this embodiment are made of silicon steel sheets), forming a laminated core with a yoke 101, a tooth 102 and a tooth tip 103. The tooth 102 is located between the yoke 101 and the tooth tip 103. The yoke 101 is located on the outside of the segmented motor stator core, and the tooth tip 103 is located on the inside of the segmented motor stator core.

[0029] In this embodiment, the tooth tip 103 at the end of the single stator core module 1 is the key innovation of the present invention. The left and right edges of the tooth tip 103 (i.e. the side that is in contact with the adjacent single stator core module 1) are not flat surfaces, but are formed by stamping to form serrated structures 1030 extending along the core axis. The serrated structures 1030 are arranged in a special way on the tooth tip 103 of the same single stator core module 1. The serrated grooves 1031 and serrated tips 1032 of the serrated structure 1030 on the left edge and the serrated grooves 1031 and serrated tips 1032 on the right edge are staggered and opposite in the axial direction. If the recessed part (serrated groove 1031) of the serrated teeth on the left edge of the single stator core module 1 and the protruding part (serrated tip 1032) of the serrated teeth on the right edge are observed at the same height in the axial direction, their positions are opposite. In other words, the "valley" on the left corresponds to the "peak" on the right.

[0030] When two adjacent sets of single stator core modules 1 are spliced, the adjacent sets of tooth tips 103 approach each other. The sawtooth tips 1032 on one set of tooth tips 103 are face-to-face and basically aligned with the sawtooth tips 1032 on the adjacent tooth tips 103 in the circumferential direction, forming a "top-top overlapping area". Without embedding, the magnetic field transition interface between adjacent tooth tips 103 after splicing is a non-linear gap. This "top-top overlapping area" replaces the straight air gap or slot with a consistent width that exists in the traditional segmented stator. When the permanent magnet of the motor rotor rotates through this splicing interface, because the interface is a continuous and alternating sawtooth shape rather than a straight gap, the change of air gap magnetic resistance is more gradual, and the "abrupt" effect of magnetic field distribution is significantly weakened, thereby effectively reducing the cogging torque and the vibration and noise it causes.

[0031] To further optimize the continuity of the magnetic circuit, in this embodiment, the width of the bottom of the sawtooth groove 1031 (i.e., the deepest recess) of each sawtooth unit of the sawtooth structure 1030 is designed to be equal to the width of the top of the sawtooth top 1032 (i.e., the highest protrusion). This equal width design ensures that in the "top-top overlapping region", the magnetic lines of force can pass through a "virtual air gap path" with a constant width, avoiding drastic changes in local magnetic flux density caused by abrupt changes in width, resulting in a better sinusoidal magnetic field effect, while also helping to balance the magnetic circuit and prevent unnecessary increase in magnetic leakage.

[0032] To ensure that the twelve individual stator core modules 1 in this embodiment can be precisely and tightly spliced ​​into a circle, each individual stator core module 1 has complementary splicing and positioning structures on the left and right end faces of its yoke 101. Specifically, on one side (left side) end face of the yoke 101, there is an inwardly recessed semi-circular groove 1011, and on the opposite side (right side) end face, there is a semi-circular boss 1012 that perfectly matches the number, shape, and size of the semi-circular groove 1011. During assembly, the semi-circular boss 1012 of one individual stator core module 1 is aligned and embedded into the semi-circular groove 1011 of the adjacent individual stator core module 1, which can achieve precise positioning in the circumferential direction and radial limiting. This concave-convex fitting structure is not only easy to assemble, but also effectively reduces the splicing gap, ensuring the roundness and concentricity of the entire stator core, laying the foundation for forming a uniform air gap.

[0033] To improve winding efficiency and consistency during production, this embodiment provides a dedicated clamping and positioning structure on the outer circumferential surface (i.e., the outer surface of the yoke 101) of each stator core module 1. This structure is located on the extension line from the central axis of the tooth 102 to the outer diameter and is an axially extending process positioning groove 1013. Before the winding process, the operator can insert the stator core module 1 into the corresponding positioning pin or protrusion on the winding fixture through this process positioning groove 1013 (the winding fixture is an existing technology product and will not be described in detail). This enables the module to be quickly and accurately positioned and secured on the fixture, preventing the module from moving or rotating during the winding process and ensuring that the coil winding position is accurate and the shape is regular.

[0034] The cross-sectional shape of the process positioning groove 1013 can be selected based on the design of the winding fixture, clamping stability, and ease of processing. Common preferred shapes include:

[0035] Rectangular groove: simple to process, large contact surface when mated with square locating pin, stable and reliable positioning;

[0036] V-groove: It has a self-centering function, which can guide the module to achieve good alignment with the tapered locating pin even with small dimensional tolerances;

[0037] Semi-circular groove: when matched with cylindrical locating pin, it ensures uniform contact stress distribution and smooth loading and unloading;

[0038] These shapes can all achieve effective positioning functions and can be adapted to the tooling conditions of a specific production line. In this embodiment, the process positioning groove 1013 is a rectangular groove.

[0039] After the single stator core module 1 is stamped and riveted, its conductive parts need to be insulated. In this embodiment, an integral plastic coating molding process is adopted. A continuous insulating layer 3 is covered on the inner side (i.e., the winding groove) of the single stator core module 1 and on the opposite side of the yoke 101 and the tooth tip 103. The insulating layer 3 is formed by injection molding of engineering plastics into the module by placing it into a specific injection mold. It can tightly wrap the surface of the core and form a reliable electrical insulation barrier to prevent short circuits between the winding enameled wire and the core.

[0040] The material constituting insulation layer 3 must possess good electrical insulation properties, mechanical strength, heat resistance, and adhesion to the iron core. Suitable engineering plastics include:

[0041] PBT (polybutylene terephthalate): has excellent heat resistance, electrical insulation and molding processability;

[0042] PA66 (Nylon 66): Good toughness, wear resistance, and high fatigue strength;

[0043] PET (polyethylene terephthalate): high mechanical strength and good dimensional stability;

[0044] LCP (Liquid Crystal Polymer): High strength, high rigidity, and high temperature resistance.

[0045] These materials can be perfectly molded into insulation layer 3 through injection molding process, which meets the reliability requirements of long-term operation of motor. In this embodiment, LCP material is used as insulation layer 3.

[0046] In this embodiment, the core body of the single stator core module 1 is formed by stamping several electrical steel sheets 2 (silicon steel sheets) into the same shape and then stacking them along the axial direction. The thickness of the silicon steel sheet is 0.35mm. This thickness takes into account both the core loss (eddy current loss and hysteresis loss) and the stacking coefficient (the actual space occupied by the core). The stacked core is fixed by physical means. Riveting is a commonly used and reliable process. That is, rivet holes are punched at specific positions of the stacked sheets, and the silicon steel sheets are tightly joined together by rivets or rivet protrusions to form a solid integral module.

[0047] Example 2

[0048] Regarding the segmented motor stator core with low cogging torque provided in Example 1, this example provides a method for preparing a segmented motor stator core with low cogging torque, including the following steps:

[0049] S1: Fabrication of a single iron core module

[0050] Stamping manufacturing: Using precision stamping dies, silicon steel strips are continuously stamped into single iron core stampings (electrical steel sheets 2). The stamping has a yoke 101, a tooth 102 and a tooth tip 103, and a sawtooth structure 1030 is formed on both sides of the tooth tip 103. A semi-circular groove 1011 and a semi-circular boss 1012 are formed on both sides of the yoke 101, and a process positioning groove 1013 is formed on the outer diameter surface.

[0051] Stacking and fastening: A predetermined number of laminations are stacked and aligned along the axial direction and fastened by riveting to form a single stator core module 1 with uniform axial dimensions;

[0052] S2: Insulation treatment

[0053] Insulation molding: A single stator core module 1 is placed in an injection mold and a continuous insulation layer 3 is formed by injection molding. The insulation layer 3 completely covers the conductive parts and does not affect the shape and function of the process positioning groove 1013 and the semi-circular concave-convex structure.

[0054] S3: Coil winding

[0055] Module clamping: The single stator core module 1 after insulation treatment is precisely clamped onto the corresponding positioning protrusion of the special winding fixture through the process positioning groove 1013 on its outer diameter surface, so as to achieve circumferential and axial fixation of the single stator core module 1 during the winding process.

[0056] Automatic winding: On the teeth 102 of the clamped and fixed single stator core module 1, the enameled wire is automatically wound using a winding machine to form a concentrated winding coil.

[0057] S4: Stator rounding and curing

[0058] Module pre-assembly: Twelve single stator core modules 1 with wound coils are pre-assembled by aligning and embedding the semi-circular boss 1012 on one side of the yoke 101 with the semi-circular groove 1011 on the other side of the yoke 101 of the adjacent module.

[0059] "Top-top coincidence" alignment: During the splicing process, ensure that the sawtooth structure 1030 on the tooth top 103 of two adjacent single stator core modules 1 presents a "top-top coincidence" distribution state, that is, the sawtooth top 1032 of one single stator core module 1 is aligned with the sawtooth top 1032 of the adjacent single stator core module 1 in the circumferential direction to form a non-embedded docking interface.

[0060] Forming a complete ring: All individual stator core modules 1 are sequentially spliced ​​together in the manner described above, and finally closed to form a complete ring stator core assembly, namely a segmented motor stator core with low cogging torque.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A segmented motor stator core with low cogging torque, comprising a single stator core module (1), characterized in that: The segmented motor stator core is composed of several groups of single stator core modules (1) spliced ​​together to form a ring. The single stator core module (1) is composed of several groups of electrical steel sheets (2). The single stator core module (1) includes an integrally formed yoke (101), a tooth (102) and a tooth tip (103). The tooth (102) is located between the yoke (101) and the tooth tip (103). The left and right sides of the tooth tip (103) respectively form serrated structures (1030) extending along the axial direction. The serrated grooves (1031) and serrated tips (1032) of the serrated structures (1030) on the left and right sides of the tooth tip (103) are staggered and opposite in the axial direction. When adjacent single stator core modules (1) are spliced, the sawtooth tops (1032) on one set of tooth tops (103) are arranged opposite to the sawtooth tops (1032) on the adjacent tooth tops (103) in the circumferential direction and form a top-top overlap.

2. The segmented motor stator core with low cogging torque according to claim 1, characterized in that: The width of the groove (1031) is equal to the width of the top of the serration (1032).

3. The segmented motor stator core with low cogging torque according to claim 1, characterized in that: The yoke (101) is provided with a semi-circular groove (1011) and a semi-circular boss (1012) on both sides, and the semi-circular groove (1011) and the semi-circular boss (1012) are adapted to each other.

4. A segmented motor stator core with low cogging torque according to claim 1, characterized in that: The yoke (101) has at least one process positioning groove (1013) on its outer circumferential surface corresponding to the central axis of the tooth (102), and the process positioning groove (1013) cooperates with the positioning protrusion on the winding fixture.

5. A segmented motor stator core with low cogging torque according to claim 4, characterized in that: The cross-sectional shape of the process positioning groove (1013) is selected from one of rectangle, V-shape or semi-circle.

6. A segmented motor stator core with low cogging torque according to claim 1, characterized in that: The inner side of the single stator core module (1) is covered with an insulating layer (3), which is formed by injection molding on the outer side of the tooth (102) and the opposite side of the yoke (101) and the tooth tip (103).

7. A segmented motor stator core with low cogging torque according to claim 1, characterized in that: The single stator core module (1) is formed by stacking several sets of electrical steel sheets (2) and fixing them together by riveting.

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