Permanent magnet surface-mounted outer rotor core assembly, wheel hub motor and electric vehicle

Abstract

The utility model provides a kind of permanent magnet surface-bonding outer rotor core assembly, hub motor and electric car, wherein outer rotor core assembly, including outer rotor core and multiple permanent magnets, the inner ring wall surface of outer rotor core is formed with multiple clamping slots being evenly spaced along its circumferential direction, permanent magnet has clamping portion, each permanent magnet is clamped in each clamping slot by each clamping portion respectively possessed to realize the limitation of outer rotor core to each permanent magnet in the radial direction and circumferential direction of outer rotor core, circumferential air slot is formed between adjacent two permanent magnets.The utility model realizes more reliable and convenient assembly between permanent magnet and outer rotor core, simplifies the assembly process of each permanent magnet, is conducive to the flexible adjustment of pole arc coefficient of each permanent magnet according to the actual performance requirement of motor, effectively reduces the magnetic flux leakage of permanent magnet on two sides of circumference, guarantees the magnetic flux of the middle region of each permanent magnet, can improve motor torque, reduces motor design cost.

Description

Technical Field

[0001] This utility model belongs to the field of motor design technology, specifically relating to a permanent magnet surface-mounted external rotor core assembly, a hub motor, and an electric vehicle. Background Technology

[0002] Hub motors integrate the drive, transmission, and braking systems into the wheel hub, eliminating mechanical components such as clutches, drive shafts, and gearboxes, thus greatly simplifying the vehicle's structure. Existing hub motors for electric two-wheelers typically employ a direct-drive configuration with an external rotor and stator. Power is directly output through the external rotor, using a stator core structure with open slots on the outer circumference. The rotor section uses surface-mounted magnetic poles, resulting in a simple magnetic circuit, limited load adaptability, and low motor efficiency. Furthermore, because electric two-wheelers often require motors with low-speed, high-torque output characteristics, it's often necessary to increase the number of permanent magnets to optimize their distribution, eliminate or reduce torque ripple, and lower copper and iron losses. Some electric vehicle hub motors have up to 60 permanent magnet poles. Permanent magnets with this number of poles are relatively small and difficult to install, requiring them to be simply arranged in a circle and glued on, making performance optimization according to motor requirements difficult.

[0003] See details Figure 1 and Figure 2 As shown in the figure, the motor core includes an outer rotor core AA and a stator core CC. The permanent magnets BB are surface-mounted and are bonded to the outer rotor core AA with adhesive. The permanent magnets BB are evenly and spaced apart in the circumferential direction of the rotor core. Due to the large number of permanent magnets BB, considering the feasibility of installation, only 60 permanent magnets BB can be completely bonded to the inner surface of the rotor core. The circumferential positioning between adjacent permanent magnets is achieved, and no gaps can be left. This makes it impossible to adjust the pole arc coefficient in this technical solution (for surface-mounted motors, the pole arc coefficient of the permanent magnet is an important parameter affecting motor performance). This results in lower performance and higher manufacturing cost for this type of motor. Utility Model Content

[0004] Therefore, this utility model provides a permanent magnet surface-mounted external rotor core assembly, a hub motor, and an electric vehicle, which can overcome the technical problems in related technologies where the installation structure of each pair of adjacent permanent magnets in the surface-mounted external rotor core assembly forms a circumferential limit on both sides, which is not conducive to the adjustment of its pole arc coefficient, resulting in low motor performance, and the large amount of permanent magnets used leads to high motor manufacturing costs.

[0005] To address the aforementioned problems, this utility model provides a permanent magnet surface-mounted external rotor core assembly, comprising an external rotor core and a plurality of permanent magnets. The inner ring wall of the external rotor core has a plurality of slots evenly spaced along its circumference. Each permanent magnet has a locking portion, and each permanent magnet is locked into its respective slot via its locking portion to achieve radial and circumferential positioning of the permanent magnets by the external rotor core. A circumferential air gap is formed between two adjacent permanent magnets.

[0006] In some embodiments, the slot is a constricted structure, and the shape and size of the snap-fit ​​part match the shape and size of the slot; and / or, each slot extends through both end faces of the outer rotor core along the axial direction of the outer rotor core, and each permanent magnet is inserted into each slot along the axial direction of the outer rotor core.

[0007] In some embodiments, the permanent magnet further includes a circumferential extension outside the slot opening of the slot, the locking portion and the circumferential extension forming a T-shape; and / or, the two ends of each permanent magnet are bonded to the two end faces of the outer rotor core, and the permanent magnets are not bonded to the slot wall of the slot.

[0008] In some embodiments, the snap-fit ​​portion has a first side surface and a second side surface that are opposite to each other in the circumferential direction of the outer rotor core, and the circumferential extension portion has a radial outer wall surface that fits against the inner ring wall surface of the outer rotor core. When projected onto any radial surface of the outer rotor core, the first side surface and the second side surface form an acute angle with the radial outer wall surface.

[0009] In some embodiments, the circumferential extension further has a third side surface and a fourth side surface that are circumferentially opposite to each other along the outer rotor core and projected onto any radial surface of the outer rotor core, wherein the extension surface of the third side surface and the extension surface of the fourth side surface intersect each other along the radial direction of the outer rotor core from the inside to the outside.

[0010] In some embodiments, the circumferential extension further includes a radial inner wall surface disposed opposite to the radial outer wall surface, wherein the radial inner wall surface is a plane.

[0011] In some embodiments, the acute angle is 85° to 89°.

[0012] In some embodiments, the radial extension length of the circumferential extension is h, and the radial extension length of the snap-fit ​​portion is H, where H = (50% to 60%)h.

[0013] This utility model also provides a hub motor, including the above-mentioned permanent magnet surface-mounted external rotor core assembly.

[0014] This utility model also provides an electric vehicle, including the aforementioned hub motor.

[0015] The permanent magnet surface-mounted external rotor core assembly, hub motor, and electric vehicle provided by this utility model have the following beneficial effects:

[0016] Each permanent magnet is engaged with a corresponding slot on the inner ring wall of the outer rotor core via its respective engaging part, ensuring reliable circumferential and radial connection to the outer rotor core. Simultaneously, a circumferential air groove is formed between adjacent permanent magnets, instead of relying on the circumferential sides of each permanent magnet to achieve circumferential restraint as in existing technologies. This results in more reliable and convenient assembly between the permanent magnets and the outer rotor core, simplifying the assembly process and allowing for flexible adjustment of the pole arc coefficient of each permanent magnet according to the actual performance requirements of the motor. The circumferential air groove between adjacent permanent magnets effectively reduces magnetic leakage on both circumferential sides, ensuring magnetic flux in the middle region of each permanent magnet and improving motor torque. Furthermore, since the dimensions of each permanent magnet do not need to consider the circumferential restraint on the inner ring wall of the outer rotor core, the circumferential width of each permanent magnet can be designed to be relatively smaller, thus reducing the overall number of permanent magnets used and consequently lowering motor design costs. Attached Figure Description

[0017] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the fit between the permanent magnet surface-mounted outer rotor core assembly and the inner rotor core in a hub motor in the prior art.

[0019] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0020] Figure 3 This is a structural schematic diagram of the cooperation state between the permanent magnet surface-mounted outer rotor core assembly and the inner rotor core in the hub motor of this utility model embodiment.

[0021] Figure 4 yes Figure 1 A magnified view of point B in the image;

[0022] Figure 5 yes Figure 3 A schematic diagram showing the assembly state of the permanent magnet and the outer rotor core.

[0023] Figure 6 This is a simulation diagram of the output torque and torque pulsation of a hub motor that did not adopt the technical solution of this utility model (i.e., before the improvement);

[0024] Figure 7 This is a simulation diagram of the output torque and torque pulsation of the hub motor using the technical solution of this utility model (i.e., the improved version);

[0025] Figure 8 This is a simulation diagram of the magnetic lines of force in the outer rotor core and inner stator core of a hub motor that did not adopt the technical solution of this utility model (i.e., before the improvement);

[0026] Figure 9 This is a simulation diagram of the magnetic lines of force in the outer rotor core and inner stator core of a hub motor using the technical solution of this utility model (i.e., the improved version).

[0027] The attached figures are labeled as follows:

[0028] 1. Outer rotor core; 2. Permanent magnet; 20. Air slot; 21. Snap-fit ​​part; 211. First side surface; 212. Second side surface; 22. Circumferential extension; 221. Radial outer wall surface; 222. Third side surface; 223. Fourth side surface; 224. Radial inner wall surface; 3. Inner stator core. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0030] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0031] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0032] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0033] See also Figures 3 to 9 As shown, according to an embodiment of the present invention, a permanent magnet surface-mounted external rotor core assembly is provided, including an external rotor core 1 and a plurality of permanent magnets 2. The inner ring wall surface (not labeled in the figure) of the external rotor core 1 is formed with a plurality of slots (not labeled in the figure) evenly spaced along its circumference. The permanent magnets 2 have a snap-fit ​​portion 21. Each permanent magnet 2 is snapped into each slot through its respective snap-fit ​​portion 21 to realize the radial and circumferential limiting connection of the external rotor core 1 to each permanent magnet 2 in the external rotor core 1. A circumferential air groove 20 is formed between two adjacent permanent magnets 2.

[0034] In this technical solution, each permanent magnet 2 is engaged with a corresponding slot on the inner ring wall of the outer rotor core 1 through its respective engaging part 21, thereby reliably limiting and connecting the permanent magnet 2 to the outer rotor core 1 in both the circumferential and radial directions. Simultaneously, a circumferential air groove 20 is formed between two adjacent permanent magnets 2, instead of relying on the circumferential sides of each permanent magnet 2 to abut against each other as in the prior art. Therefore, a more reliable and convenient assembly between the permanent magnet 2 and the outer rotor core 1 is achieved, simplifying the assembly process of each permanent magnet 2 and facilitating flexible adjustment of the pole arc coefficient of each permanent magnet 2 according to the actual performance requirements of the motor. Figure 1In the prior art shown, the pole arc coefficient of each permanent magnet is locked at 360° / n (where n is the number of permanent magnets) due to the contact of its circumferential side. The circumferential air groove 20 formed between two adjacent permanent magnets 2 can effectively reduce the magnetic leakage on both sides of the permanent magnet 2, ensure the magnetic flux in the middle region of each permanent magnet 2, and improve the motor torque. In addition, since the size of each permanent magnet 2 does not need to take into account the circumferential limit of its surface attached to the inner ring wall of the outer rotor core 1, the circumferential width of each permanent magnet 2 can be designed to be relatively smaller, which can reduce the overall amount of permanent magnets 2 used, and thus reduce the motor design cost.

[0035] In some embodiments, the slot is a constricted structure, and the shape and size of the latching part 21 match the shape and size of the slot.

[0036] In this technical solution, by designing the card slots as a narrow-mouth structure, that is, the width of the slot opening of each card slot is smaller than the distance between the inner walls of each card slot, and at the same time, the shape and size of each card contact 21 match the shape and size of each card slot, the anti-detachment design of each permanent magnet 2 in the card slot is realized, and the structure is simple and reliable.

[0037] In some embodiments, each of the slots extends through the two end faces (i.e., the two end faces at both ends of the outer rotor core 1) along the axial direction of the outer rotor core 1, and each of the permanent magnets 2 is inserted into the slot along the axial direction of the outer rotor core 1.

[0038] In this technical solution, by designing the slots to extend through both axial ends of the outer rotor core 1, each permanent magnet 2 can be assembled with its snap-fit ​​portion 21 and the slots (which have a constricted opening) in an insert-like manner along the axial direction of the outer rotor core 1. This further simplifies the assembly process and the fabrication of the rotor laminations of the outer rotor core 1, ensuring that the structures of each rotor lamination are identical and eliminating the need for different rotor laminations for the axial positioning of the permanent magnets 2. Furthermore, the two ends of each permanent magnet 2 are bonded to the end faces of the outer rotor core 1 (e.g., using epoxy resin), while the permanent magnets 2 are not bonded to the slot walls, further simplifying the fabrication process of the outer rotor core assembly.

[0039] Further integration Figures 3 to 5 As shown, the permanent magnet 2 also includes a circumferential extension 22 located outside the slot of the slot. In some embodiments, the snap-fit ​​portion 21 and the circumferential extension 22 form a T-shape. It can be understood that at this time, the permanent magnet 2 is a structure that is symmetrical about the diameter of the outer rotor core 1, and the permanent magnet 2 is an integral structure.

[0040] In this technical solution, the permanent magnet 2 forms a T-shaped structure that is symmetrical from left to right, and the radial thickness of the middle permanent magnet is greater than that of the permanent magnets on the left and right sides. Under the premise that the volume of the permanent magnet 2 remains unchanged, the radial thickness of the middle permanent magnet can be designed to be larger, so that the effective magnetic flux (main magnetic flux) under each magnetic pole is higher, which plays a role in concentrating magnetism, reducing the inter-pole leakage magnetic flux between two adjacent permanent magnets, thereby improving the output torque of the motor.

[0041] In some embodiments, the radial extension length of the circumferential extension 22 is h, and the radial extension length of the snap-fit ​​portion 21 is H, where H = (50% to 60%)h, and the aforementioned radial extension length is also the aforementioned radial thickness.

[0042] In this technical solution, H is 50%-60% of h. This ratio range can ensure the optimal pole arc coefficient of the motor. If this ratio is too large or too small, it will cause the pole arc coefficient of the motor to change, resulting in insufficient motor torque and increased cost.

[0043] In some embodiments, the snap-fit ​​portion 21 has a first side surface 211 and a second side surface 212 that are opposite to each other in the circumferential direction of the outer rotor core 1, and the circumferential extension portion 22 has a radial outer wall surface 221 that fits against the inner ring wall surface of the outer rotor core 1. When projected onto any radial surface of the outer rotor core 1, the first side surface 211 and the second side surface 212 form an acute angle with the radial outer wall surface 221. In one specific embodiment, the acute angle is 85° to 89°, and in another specific embodiment, it is 87°.

[0044] In this technical solution, the permanent magnet 2 and the outer rotor core 1 are reliably connected by tilting the two opposite sides of the snap-fit ​​part 21 of the permanent magnet 2. The structure is simple and the positioning is reliable.

[0045] In some embodiments, the circumferential extension 22 further has a third side surface 222 and a fourth side surface 223 that are circumferentially opposite to each other along the outer rotor core 1. When projected onto any radial surface of the outer rotor core 1, the extension surface of the third side surface 222 and the extension surface of the fourth side surface 223 intersect each other along the radial direction of the outer rotor core 1 from the inside to the outside. That is, the two circumferential sides of the aforementioned circumferential extension 22 approach each other along the radial direction of the outer rotor core 1 from the inside to the outside.

[0046] In this technical solution, the two circumferential sides of the aforementioned circumferential extension 22 approach each other from the inside to the outside along the radial direction of the outer rotor core 1, which can further increase the distance between two adjacent permanent magnets 2, reduce magnetic leakage between magnets, and increase motor torque.

[0047] In some embodiments, the circumferential extension 22 further includes a radial inner wall surface 224 disposed opposite to the radial outer wall surface 221. The radial inner wall surface 224 is a plane, that is, a projection on any radial plane of the outer rotor core 1. The projection of the radial inner wall surface 224 is a straight line.

[0048] In this technical solution, the radial inner wall surface 224 of the circumferential extension 22 is improved from the arc surface in the prior art to a plane, which objectively realizes the pole-cutting treatment of the side of the permanent magnet 2 facing the inner stator core 3, so that the air gap between the stator and rotor presents an uneven change in the circumferential direction of the outer rotor core 1, thereby achieving the effect of concentrating magnets to increase torque and reduce torque pulsation.

[0049] See comparison Figure 6 and Figure 7 As shown, the motor core adopting the technical solution of this utility model ( Figure 7 ) and traditional motor core ( Figure 6 Compared to the previous model, the hub motor using the stator and rotor core of this invention increases the maximum output torque from 82 Nm to 87.4 Nm while keeping the material cost unchanged. This represents a 6.6% increase in output torque and a 40.5% reduction in torque ripple from 17% to 12.1%.

[0050] See comparison Figure 8 and Figure 9 As shown, compared with traditional motor cores, the motor core using the permanent magnet and rotor core of this utility model has smoother magnetic lines of force, and reduced abrupt changes in magnetic lines of force and magnetic leakage.

[0051] According to an embodiment of the present invention, a hub motor is also provided, including an inner stator core assembly (including an inner stator core 3 and stator windings wound on each stator tooth) and an outer rotor core assembly fitted on the radially outer side of the inner stator core assembly, wherein the outer rotor core assembly is the aforementioned permanent magnet surface-mounted outer rotor core assembly.

[0052] According to an embodiment of the present invention, an electric vehicle, particularly an electric two-wheeled vehicle, is also provided, including the aforementioned hub motor.

[0053] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0054] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A permanent magnet surface-mounted external rotor core assembly, characterized in that, The device includes an outer rotor core (1) and a plurality of permanent magnets (2). The inner ring wall of the outer rotor core (1) has a plurality of slots evenly spaced along its circumference. The permanent magnets (2) have a snap-fit ​​part (21). Each permanent magnet (2) snaps into each slot through its respective snap-fit ​​part (21) to achieve the limiting of each permanent magnet (2) by the outer rotor core (1) in the radial and circumferential directions of the outer rotor core (1). A circumferential air groove (20) is formed between two adjacent permanent magnets (2).

2. The permanent magnet surface-mounted external rotor core assembly according to claim 1, characterized in that, The slot is a constricted structure, and the shape and size of the snap-fit ​​part (21) match the shape and size of the slot; and / or, each slot passes through the two end faces of the outer rotor core (1) along the axial direction of the outer rotor core (1), and each permanent magnet (2) is inserted into each slot along the axial direction of the outer rotor core (1).

3. The permanent magnet surface-mounted external rotor core assembly according to claim 2, characterized in that, The permanent magnet (2) further includes a circumferential extension (22) outside the slot of the slot, and the snap-fit ​​portion (21) and the circumferential extension portion (22) together form a T-shape; and / or, the two ends of each permanent magnet (2) are bonded to the two end faces of the outer rotor core (1), and the permanent magnet (2) is not bonded to the slot wall of the slot.

4. The permanent magnet surface-mounted external rotor core assembly according to claim 3, characterized in that, The snap-fit ​​portion (21) has a first side surface (211) and a second side surface (212) that are opposite to each other in the circumference of the outer rotor core (1). The circumferential extension portion (22) has a radial outer wall surface (221) that fits against the inner ring wall surface of the outer rotor core (1). When projected onto any radial surface of the outer rotor core (1), the first side surface (211) and the second side surface (212) form an acute angle with the radial outer wall surface (221).

5. The permanent magnet surface-mounted external rotor core assembly according to claim 4, characterized in that, The circumferential extension (22) also has a third side surface (222) and a fourth side surface (223) that are circumferentially opposite to each other along the outer rotor core (1), projected onto any radial surface of the outer rotor core (1), and the extension surface of the third side surface (222) and the extension surface of the fourth side surface (223) intersect each other along the radial direction of the outer rotor core (1) from the inside to the outside.

6. The permanent magnet surface-mounted external rotor core assembly according to claim 4, characterized in that, The circumferential extension (22) also includes a radial inner wall surface (224) disposed opposite to the radial outer wall surface (221), and the radial inner wall surface (224) is a plane.

7. The permanent magnet surface-mounted external rotor core assembly according to claim 4, characterized in that, The acute angle is 85° to 89°.

8. The permanent magnet surface-mounted external rotor core assembly according to claim 3, characterized in that, The radial extension length of the circumferential extension (22) is h, and the radial extension length of the snap-fit ​​part (21) is H, where H = (50% to 60%)h.

9. A hub motor, characterized in that, The permanent magnet surface-mounted external rotor core assembly includes any one of claims 1 to 8.

10. An electric vehicle, characterized in that, Including the hub motor as described in claim 9.

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