Pole shoe mounting and positioning structure for an electric machine

Abstract

The application relates to a pole shoe mounting and positioning structure of a motor, which comprises a stator core, the stator core comprises a plurality of stator teeth, a coil is sleeved on the stator teeth, a pole shoe is mounted at the end of the stator teeth, and a plurality of insulating baffle plates are inserted into the gap between the inner circumferential surface of the coil and the side surface of the stator teeth, the two side surfaces of each stator tooth are provided with the insulating baffle plates, and the insulating baffle plates are in contact with the pole shoes; the insulating baffle plate comprises an insertion part and a baffle part, the width of the baffle part is larger than that of the insertion part, a plurality of guide inclined surfaces are formed on the insertion part, and the baffle part presses the pole shoe after the insertion of the insulating baffle plate is completed. Compared with the prior art, the opening of the stator slot is reduced in the mounting of the pole shoe, torque fluctuation is reduced, tooth slot torque is reduced, radial force fluctuation is reduced, and the motor NVH performance is improved; the simple and low-cost insulating bamboo stick can make the coil winding firm, fill the gap, increase the insulation reliability, and prevent the pole shoe from slipping due to the motor vibration.

Description

Technical Field

[0001] This invention relates to a pole shoe mounting and positioning structure for an electric motor, belonging to the field of electric motor technology. Background Technology

[0002] Currently, the stator in most external rotor motors uses an open-slot design, meaning the top of the stator slot (the side closest to the air gap) is open, with the slot opening directly facing the air gap. There is a magnetic attraction between the permanent magnets on the rotor and the stator core. When the rotor rotates, the magnetic reluctance of the magnetic circuit changes drastically as the magnets pass through the slot opening. The wide slot opening causes a very steep and drastic change in magnetic reluctance, generating periodic torque pulsations—that is, the cogging torque of the open slot is large. Simultaneously, the presence of the open slot severely distorts the magnetic field distribution in the air gap. Because the permeability at the slot opening is much lower than that of silicon steel sheets, the magnetic field lines are distorted, generating a large number of spatial harmonics, especially high-order harmonics. The high harmonic content in the air gap magnetic flux density leads to harmful radial force waves with large amplitude and low order, causing motor vibration and noise, reducing motor efficiency, and causing heat generation. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a pole shoe mounting and positioning structure for a motor that reduces the opening of the stator slots and decreases cogging torque.

[0004] To achieve the objective, the technical solution adopted by this invention is:

[0005] The pole shoe mounting and positioning structure of the motor includes a stator core, the stator core including multiple stator teeth, a coil sleeved on the stator teeth, a pole shoe mounted at the end of the stator teeth, and multiple insulating baffles inserted into the gap between the inner circumferential surface of the coil and the side surface of the stator teeth. Each stator tooth has an insulating baffle on both sides, and the insulating baffle is in contact with the pole shoe.

[0006] As a further optimization of the above technical solution: the insulating baffle includes an insertion part and a blocking part, the width of the blocking part is greater than the width of the insertion part, and the insertion part is provided with several guide slopes. After the insulating baffle is inserted, the blocking part presses down on the pole shoe.

[0007] As a further optimization of the above technical solution: the insulating baffle is also provided with a number of protrusions, the side of the protrusion near the insertion part is an insertion slope, and the side of the protrusion near the baffle is a positioning baffle.

[0008] As a further optimization of the above technical solution: the guide slope includes a first guide slope located on both sides of the insertion part, a second guide slope located on the upper surface of the insertion part, and a third guide slope located at the head of the insertion part.

[0009] As a further optimization of the above technical solution: the insulating baffle also includes an intermediate portion located between the insertion portion and the baffle portion, and the protrusion is located on the upper surface of the intermediate portion.

[0010] As a further optimization of the above technical solution: the end of the stator tooth is provided with a mounting protrusion, and the side of the pole shoe is provided with a corresponding mounting groove, and the mounting protrusion is inserted into the mounting groove.

[0011] Compared with the prior art, the installation of the pole shoes in this invention reduces the opening of the stator slots, reduces torque fluctuation, reduces cogging torque, and reduces radial force fluctuation, thereby improving the NVH performance of the motor; the simple and inexpensive insulating bamboo sticks not only ensure the coil is firmly wound, fill gaps, and increase insulation reliability, but also prevent the pole shoes from slipping due to motor vibration; the positioning facets on the protrusions prevent the insulating baffle from accidentally moving outwards, and the insulating paint makes the insulating baffle adhere to the stator core, further reducing the risk of the insulating baffle falling off. Attached Figure Description

[0012] Figure 1 This is an exploded structural diagram of the present invention.

[0013] Figure 2 yes Figure 1 A magnified structural diagram of point A in the middle.

[0014] Figure 3 This is a three-dimensional structural diagram of the insulating baffle in this invention. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. For example... Figure 1-3 As shown, an electric motor includes a stator core 1, which includes a connecting ring 11 and multiple stator teeth 12 located on the connecting ring 11. Coils are wound on the stator teeth 12, and stator slots are formed between adjacent stator teeth 12. The coils are specifically flat wire coils, and several flat wire coils are wound from a single continuous conductor to form a flat wire coil group 2. Several groups of flat wire coil groups 2 are provided. After the flat wire coil groups 2 are wound, they are wound onto the stator teeth 12, and all flat wire coil groups 2 are connected to form a winding. Using flat wire coils increases the slot fill factor, thereby increasing the power density of the motor. Furthermore, the installation method of pre-wound flat wire coil groups 2 being wound onto the stator teeth 12 significantly reduces the difficulty of winding slot crossing, making winding formation simpler, more convenient, and faster, simplifying the installation process, reducing costs, and improving material utilization.

[0016] In the above technical solution: a pole shoe 3 is detachably installed at the end of the stator tooth 12. The end of the stator tooth 12 is provided with a mounting protrusion 121, and the side of the pole shoe 3 is provided with a corresponding mounting groove 31. Both the mounting protrusion 121 and the mounting groove 31 are dovetail-shaped. The mounting protrusion 121 is inserted into the mounting groove 31, allowing the pole shoe 3 to be installed at the end of the stator tooth 12. The pole shoe 3 and the stator core 1 are separately configured, facilitating the installation of the wound flat wire coil group 1. Simultaneously, the installation of the pole shoe 3 reduces the opening of the stator slot, decreasing torque fluctuation, reducing cogging torque, and lowering radial force fluctuation, thereby improving the motor's NVH (noise, vibration, and harshness) performance.

[0017] The above technical solution also includes insulating paper 4, which is closely attached to and covers the inner wall of the stator slot. After the flat wire coil group 2 is sleeved on the stator tooth 12, the inner circumferential surface of the flat wire coil group 2 is in contact with the insulating paper 4 to provide insulation and prevent the flat wire coil group 2 from conducting electricity.

[0018] The above technical solution also includes multiple insulating baffles 5, which are inserted into the gap between the inner circumference of the coil and the side of the stator tooth 12. Each stator tooth 12 has an insulating baffle 5 on both sides, and the insulating baffles 5 contact the pole shoe 3. Compared to an integrated insulating frame (where the insulating paper 4 and insulating baffles 5 are integrally formed to create the insulating frame, and the flat wire coil is wound on the insulating frame), this insulation solution, using insulating paper 4 and insulating baffles 5, offers higher motor withstand voltage, higher slot fill factor, and lower cost.

[0019] In the above technical solution: the insulating baffle 5 includes an insertion part 51, a stop part 52, and an intermediate part 53 located between the insertion part 51 and the stop part 52. The width of the stop part 52 is greater than the width of the insertion part 51 and also greater than the width of the intermediate part 53, making the insulating baffle 5 approximately T-shaped. Several guide slopes are formed on the insertion part 51. After the insulating baffle 5 is inserted, the stop part 52 presses down on the pole shoe 3. The guide slopes include a first guide slope 59 located on both sides of the insertion part 51, a second guide slope 54 located on the upper surface of the insertion part 51, and a third guide slope 55 located at the head of the insertion part 51.

[0020] In the above technical solution: the insulating baffle 5 is also provided with several protrusions 56. The side of the protrusion 56 near the insertion part 51 is the insertion slope 57, and the side of the protrusion 56 near the stop part 52 is the positioning stop 58. The protrusion 56 is located on the upper surface of the middle part 53. The first guide slope 59, the second guide slope 54, the third guide slope 55 and the insertion slope 57 guide the insertion process of the insulating baffle 5, making the insertion process smoother. After the insulating baffle 5 is inserted, the stop part 52 presses down on the mounting protrusion 121 and the pole shoe 3 to prevent the installation between the pole shoe 3 and the stator tooth 12 from sliding and to prevent the pole shoe 3 from falling out; at the same time, the positioning stop 58 on the protrusion 56 prevents the insulating baffle 5 from accidentally moving outward and to prevent the insulating baffle 5 from falling out. The simple-shaped and low-cost insulating bamboo sticks not only make the coil wound firmly, fill the gaps and increase the insulation reliability, but also prevent the pole shoe 3 from slipping off due to motor vibration.

[0021] In the above technical solution: the connecting ring 11 of the stator core 1 is composed of multiple arc-shaped core segments. Each core segment has a fixing groove 13 and a fixing block 14 at both ends, both being dovetail-shaped. All core segments are connected end-to-end, allowing the fixing grooves 13 and fixing blocks 14 of adjacent segments to interlock and fix each other, forming a ring-shaped stator core. The stator teeth 12 are integrally formed on the outer circumferential surface of the connecting ring 11. The motor in this invention is a hub motor, and each core segment has a total of eight stator teeth 12. The stator core 1 is assembled in segments, improving material utilization and reducing costs.

[0022] In the above technical solution: each flat wire coil group 2 includes four flat wire coils formed by winding a continuous conductor, that is, the flat wire coil group 2 of the present invention is specifically a four-slot continuous-wound flat wire coil group. At the same time, the height of the cross-slot line 21 between two adjacent flat wire coils is higher than the height of the flat wire coil, thus shortening the distance between the cross-slot lines 21 at both ends of the middle flat wire coil (i.e., Figure 2 The distance between the two slot lines 21 marked in the figure is used to prevent the width of the flat wire coil from being too wide and interfering with the pole shoe 3. Of course, two-strand flat wire coils or six-strand flat wire coils can also be set, but two-strand flat wire coils have more welding points, while six-strand flat wire coils are more difficult to wind and have a slower winding speed. Therefore, the four-slot flat wire coil group of the present invention ensures the winding speed and reduces the number of welding points.

[0023] In the above technical solution: the flat wire coil group 2 is made of aluminum wire, which greatly reduces the material cost of the flat wire coil group 2 while meeting the lightweight requirements of the motor. Multiple flat wire coil groups 2 are laser welded together. When aluminum wire cannot meet the actual motor power requirements, copper wire can be replaced with the same mounting structure to further increase the motor power.

[0024] The installation process of this invention is as follows: First, insulating paper 4 is placed in the stator slot; then, the pre-wound flat wire coil group 2 is sleeved on the stator tooth 12, so that the inner circumferential surface of the flat wire coil group 2 is in contact with the insulating paper 4; then, the pole shoe 3 is installed at the end of the stator tooth 12; next, the insulating baffle 5 is inserted into the gap between the flat wire coil and the side of the stator tooth 12; finally, varnish is applied to allow the insulating varnish to fully penetrate into every gap of the winding. The insulating varnish makes the insulating baffle 5 adhere to the stator core 1, further reducing the risk of the insulating baffle 5 falling off.

[0025] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should fall within the protection scope of the present invention.

Claims

1. A pole shoe mounting and positioning structure for an electric motor, comprising a stator core (1), wherein the stator core (1) includes a plurality of stator teeth (12), and a coil is sleeved on the stator teeth (12), characterized in that... The stator tooth (12) is equipped with a pole shoe (3) at its end and also includes multiple insulating baffles (5). The insulating baffles (5) are inserted into the gap between the inner circumferential surface of the coil and the side surface of the stator tooth (12). Each stator tooth (12) has an insulating baffle (5) on both sides. The insulating baffles (5) are in contact with the pole shoe (3). The insulating baffles (5) include an insertion part (51) and a blocking part (52). The width of the blocking part (52) is greater than the width of the insertion part (51). The insertion part (51) has several guide slopes. After the insulating baffles (5) are inserted, the blocking part (52) presses down on the pole shoe (3). The insulating baffles (5) also have several protrusions (56). The side of the protrusions (56) near the insertion part (51) is an insertion slope (57), and the side of the protrusions (56) near the blocking part (52) is a positioning blocking surface (58).

2. The pole shoe mounting and positioning structure for the motor according to claim 1, characterized in that... The guide slope includes a first guide slope (59) located on both sides of the insertion part (51), a second guide slope (54) located on the upper surface of the insertion part (51), and a third guide slope (55) located at the head of the insertion part (51).

3. The pole shoe mounting and positioning structure for the motor according to claim 1, characterized in that... The insulating baffle (5) also includes an intermediate portion (53) located between the insertion portion (51) and the baffle portion (52), and the protrusion (56) is located on the upper surface of the intermediate portion (53).

4. The pole shoe mounting and positioning structure for the motor according to claim 1, characterized in that... The stator tooth (12) has a mounting protrusion (121) at its end, and the pole shoe (3) has a corresponding mounting groove (31) on its side. The mounting protrusion (121) is inserted into the mounting groove (31).

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