Outer rotor assembly, outer rotor wheel hub motor, electric vehicle
By setting a chamfered structure on the outer rotor core and optimizing the shape of the permanent magnet, the problem of low magnetic flux density in the outer rotor motor was solved, the output torque and torque density were improved, the motor performance was optimized, and torque fluctuations were suppressed.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GREE ELECTRIC APPLIANCE INC OF ZHUHAI
- Filing Date
- 2025-06-23
- Publication Date
- 2026-06-19
Smart Images
Figure CN224385173U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of motor design technology, specifically relating to an external rotor assembly, an external rotor hub motor, and an electric vehicle. Background Technology
[0002] The power system of new energy vehicles adopts hub motor technology, which has many advantages such as simple structure, high transmission efficiency, and independent control of driving and braking torque, representing an important direction for the development of the next generation of new energy vehicles.
[0003] In-wheel motors integrate the drive, transmission, and braking systems entirely within the wheel hub, eliminating mechanical components such as clutches, drive shafts, and gearboxes, thus greatly simplifying the vehicle's structure. In-wheel motors are categorized by their drive method into geared drive and direct drive. Geared drive places the reduction mechanism between the motor and the wheel, achieving speed reduction and torque increase. However, the added gear transmission structure leads to accelerated gear wear at high speeds, reducing the motor's lifespan. Furthermore, this type of motor has relatively poor heat dissipation. Direct drive, on the other hand, eliminates the intermediate link and primarily uses an external rotor motor structure, offering advantages such as simple structure, fast dynamic response, further improved efficiency, and reduced axial dimensions.
[0004] As a key component of electric vehicles, the performance of in-wheel motors directly affects the overall quality of the vehicle. Due to the limited space inside a car wheel, the outer diameter of the in-wheel motor is restricted, thus requiring it to meet requirements such as high power density and high torque density. Furthermore, in permanent magnet motors, cogging torque is unavoidable, leading to torque fluctuations that directly impact the ride comfort of electric vehicles. Utility Model Content
[0005] Therefore, this utility model provides an external rotor assembly, an external rotor hub motor, and an electric vehicle, which can overcome the technical problem in related technologies where the magnetic flux density amplitude at the rotor of an external rotor motor using an external rotor assembly is too low, resulting in low motor output torque and motor torque density.
[0006] To address the aforementioned problems, this utility model provides an external rotor assembly, including an external rotor core. Multiple permanent magnets are uniformly and spaced along the circumference of the inner circular wall of the external rotor core. Each permanent magnet has an inner sidewall away from the inner circular wall and an outer sidewall conforming to the inner circular wall. The permanent magnet also has a first sidewall connecting the first ends of the inner and outer sidewalls, and a second sidewall connecting the second ends of the inner and outer sidewalls. The first sidewall includes a first straight wall and a second straight wall. The first end of the first straight wall is connected to the first end of the inner sidewall, and the second end of the first straight wall is connected to the second end of the inner sidewall. The first end of the second straight wall is connected to the second end of the outer wall, and the second straight wall is inclined toward the center of the circumferential length of the permanent magnet along a direction away from the inner circular wall surface; and / or, the second side wall includes a third straight wall and a fourth straight wall, the first end of the third straight wall is connected to the second end of the inner wall, the second end of the third straight wall is connected to the first end of the fourth straight wall, the second end of the fourth straight wall is connected to the second end of the outer wall, and the fourth straight wall is inclined toward the center of the circumferential length of the permanent magnet along a direction away from the inner circular wall surface.
[0007] In some embodiments, each of the permanent magnets has a line of symmetry, and the first sidewall and the second sidewall are symmetrical about the line of symmetry.
[0008] In some embodiments, the radial distance between the inner sidewall and the outer sidewall is dc0, the first straight wall and the third straight wall both extend radially along the outer rotor core, the radial length of the first straight wall is dc1, dc1 / dc0 = 0.45~0.55; and / or, the radial length of the third straight wall is dc2, dc2 / dc0 = 0.45~0.55.
[0009] In some embodiments, the angle between the radial extension of the first straight wall and the second straight wall is a1, where a1 = 35° to 42°; and / or, the angle between the radial extension of the third straight wall and the fourth straight wall is a2, where a1 = 35° to 42°.
[0010] In some embodiments, the inner sidewall is concentric with the inner circular wall surface, and / or the outer sidewall is concentric with the inner circular wall surface.
[0011] This utility model also provides an external rotor hub motor, including an external rotor assembly and a stator assembly located in the inner circular hole of the external rotor core of the external rotor assembly, wherein the external rotor assembly is the aforementioned external rotor assembly.
[0012] In some embodiments, the stator assembly includes a stator core having a plurality of stator teeth extending radially outward therefrom, each stator tooth being evenly spaced along the circumference of the stator core, and each stator tooth having a tooth shoe radial thickness of D, where D = 0.8–1.3 mm.
[0013] In some embodiments, the tooth shoe shoulder inclination angle of each stator tooth is b, where b = 110° to 115°.
[0014] In some embodiments, a stator slot is formed between two adjacent stator teeth, and a slot opening is formed between two adjacent tooth shoes, wherein the width of the slot opening is E, and E / D = 2.6 to 3.
[0015] This utility model also provides an electric vehicle, including the aforementioned external rotor hub motor.
[0016] This utility model provides an external rotor assembly, an external rotor hub motor, and an electric vehicle, which have the following characteristics:
[0017] Beneficial effects:
[0018] By forming a chamfered structure at both ends of the permanent magnet on the side away from the stator core (that is, the side that fits the inner circular wall of the outer rotor core), the two circumferential ends of the permanent magnet on the radially outer side are shrunken. This optimizes the magnetic flux density distribution of the rotor core, increases the magnetic flux density at the rotor, and thus increases the magnetic flux density content in the air gap between the stator and rotor, thereby increasing the output torque and torque density. It also optimizes the back EMF waveform of the motor, which helps to suppress torque fluctuations.
[0019] The pole-cutting thickness and pole-cutting angle of each permanent magnet were limited, which further optimized the shape of the permanent magnet, and further optimized the back EMF waveform and torque pulsation of the motor, and optimized the magnetic flux density distribution of the motor rotor core. Under the aforementioned constraints on pole-cutting thickness and pole-cutting angle, the permanent magnet structure shape reached the optimal level, and the effects of increasing air gap magnetic flux density, suppressing torque fluctuation and increasing output torque reached the optimal level.
[0020] Constraining the radial thickness of the tooth shoe and the inclination angle of the tooth shoe shoulder can ensure that the tooth tip height and angle (i.e., the aforementioned tooth shoe shoulder inclination angle) reach the optimal level, preventing the tooth tip height from being too low or the angle from being too small, which would lead to saturation of the tooth tip magnetic flux and thus low utilization of the permanent magnet material. At the same time, it can also prevent the tooth tip height from being too high or the angle from being too large, which would lead to a reduction in the area of the stator slot and thus a decrease in the slot utilization rate.
[0021] Constraining the E / D ratio optimizes the slot width, preventing excessively large slots from increasing magnetic leakage and excessively small slots from causing difficulties in heat dissipation and winding. Furthermore, this constraint ensures that the motor's air gap magnetic flux density waveform is closest to a sine wave, which helps reduce motor torque fluctuations and achieves optimal torque output and overall motor performance. Attached Figure Description
[0022] 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.
[0023] Figure 1 This is a schematic diagram of the structure of the external rotor hub motor in this embodiment of the utility model (some components are omitted, and the projection along the motor axis on any radial plane is shown).
[0024] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;
[0025] Figure 3 yes Figure 1 A magnified view of a section at point B in the middle;
[0026] Figure 4 This is a simulation diagram of the output torque and torque pulsation of an external rotor hub motor that does not adopt this application;
[0027] Figure 5 This is a simulation diagram of the output torque and torque pulsation of the external rotor hub motor using the method described in this application.
[0028] The attached figures are labeled as follows:
[0029] 1. Outer rotor assembly; 11. Outer rotor core; 12. Permanent magnet; 121. Inner side wall; 122. Outer side wall; 1231. First straight wall; 1232. Second straight wall; 1241. Third straight wall; 1242. Fourth straight wall; 21. Stator core; 211. Stator teeth; 212. Stator slots; 213. Stator yoke. Detailed Implementation
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] See also Figures 1 to 5As shown, according to an embodiment of the present invention, an outer rotor assembly is provided, including an outer rotor core 11. A plurality of permanent magnets 12 are uniformly and spaced along the circumferential direction on the inner circular wall of the outer rotor core 11. Adjacent permanent magnets 12 form a space in the circumferential direction, and magnetic adhesive (e.g., epoxy resin) is filled in the space to achieve a reliable connection between each permanent magnet 12 and the inner circular wall of the outer rotor core 11. On any radial plane of the outer rotor core 11, each permanent magnet 12 has an inner sidewall 121 away from the inner circular wall and an outer sidewall 122 attached to the inner circular wall. The permanent magnet 12 also has a first end (i.e., ...) connected to the inner sidewall 121 and the outer sidewall 122 respectively. Figure 2 The first sidewall (not labeled in the figure) between the left end of the indicated orientation and the second end (i.e., the second end of the inner sidewall 121 and the outer sidewall 122 respectively) and the second end of the inner sidewall 121 and the outer sidewall 122 respectively. Figure 2 The second sidewall (not labeled in the figure) between the right end (shown in the orientation) and the first sidewall includes a first straight wall 1231 and a second straight wall 1232. The first end of the first straight wall 1231 is connected to the first end of the inner sidewall 121, and the second end of the first straight wall 1231 is connected to the first end of the second straight wall 1232. The second end of the second straight wall 1232 is connected to the first end of the outer sidewall 122. Along a direction away from the inner circular wall surface, the second straight wall 1232 is inclined towards the side closer to the center of the circumferential length of the permanent magnet 12, that is, forming the radial outer side of the permanent magnet 12 and the left sidewall (i.e., the... Figure 2 The permanent magnet 12 is located on the left side wall. The structure includes a chamfered corner between the two sides. Alternatively, the second side wall includes a third straight wall 1241 and a fourth straight wall 1242. The first end of the third straight wall 1241 is connected to the second end of the inner side wall 121, the second end of the third straight wall 1241 is connected to the first end of the fourth straight wall 1242, and the second end of the fourth straight wall 1242 is connected to the second end of the outer side wall 122. Along a direction away from the inner circular wall, the fourth straight wall 1242 is inclined towards the side closer to the center of the circumferential length of the permanent magnet 12, thus forming the radial outer side of the permanent magnet 12 and the right side wall (i.e.,...). Figure 2 The permanent magnet 12 is located in the chamfered structure between the right-side wall surfaces. Figure 2 The orientation of the view shown is for reference, and the aforementioned circumferential length is also the length of the permanent magnet 12 extending in the left and right directions.
[0035] In this technical solution, by forming a chamfered structure at both ends of the permanent magnet 12 on the side away from the stator core (that is, the side that fits the inner circular wall of the outer rotor core 11), the two circumferential ends of the permanent magnet 12 on the radially outer side are shrunken. This optimizes the magnetic flux density distribution of the rotor core, increases the magnetic flux density at the rotor, that is, increases the magnetic flux density content of the air gap between the stator and rotor, thereby increasing the output torque and torque density. It also optimizes the back EMF waveform of the motor, which is beneficial for suppressing torque fluctuations.
[0036] In some embodiments, each of the permanent magnets 12 has a line of symmetry, and the first sidewall and the second sidewall are symmetrical about the line of symmetry.
[0037] In this technical solution, the chamfered structures on the left and right sides of each permanent magnet 12 are symmetrical to each other. This can reduce the difficulty of manufacturing the permanent magnet 12 and further improve the uniformity of magnetic flux density distribution.
[0038] See details Figure 2 As shown, in some embodiments, the radial distance between the inner sidewall 121 and the outer sidewall 122 is dc0, the first straight wall 1231 and the third straight wall 1241 both extend radially along the outer rotor core 11, the radial length of the first straight wall 1231 is dc1, dc1 / dc0 = 0.45~0.55; and / or, the radial length of the third straight wall 1241 is dc2, dc2 / dc0 = 0.45~0.55, further, the angle formed between the radial extension of the first straight wall 1231 and the second straight wall 1232 is a1, a1 = 35°~42°; and / or, the angle formed between the radial extension of the third straight wall 1241 and the fourth straight wall 1242 is a2, a1 = 35°~42°.
[0039] In this technical solution, the pole-cutting thickness and pole-cutting angle of each permanent magnet 12 are limited, so that the shape of the permanent magnet 12 is further optimized, which can further optimize the back EMF waveform and torque pulsation of the motor, and optimize the magnetic flux density distribution of the motor rotor core. Under the aforementioned constraints on pole-cutting thickness and pole-cutting angle, the structural shape of the permanent magnet 12 reaches the optimal, and the effects of increasing the air gap magnetic flux density, suppressing torque fluctuation and increasing output torque are optimal.
[0040] In some embodiments, the inner sidewall 121 is concentric with the inner circular wall surface, and / or the outer sidewall 122 is concentric with the inner circular wall surface.
[0041] In this technical solution, the permanent magnet 12 is roughly fan-shaped (before the corners are cut) when projected onto the axial direction of the iron core. This shape of the permanent magnet 12 can help ensure the uniformity of magnetic flux density on the one hand, and facilitate the fitting and assembly of the permanent magnet 12 with the inner circular wall of the outer rotor iron core 11 on the other hand.
[0042] According to an embodiment of the present invention, an external rotor hub motor is also provided, specifically a direct-drive external rotor hub motor, including an external rotor assembly 1 and a stator assembly (not indicated in the figure, and only the stator core is shown) located in the inner circular hole (not indicated in the figure) of the external rotor core 11 of the external rotor assembly (1), wherein the external rotor assembly 1 is the aforementioned external rotor assembly.
[0043] In some embodiments, the stator assembly includes a stator core 21 having a plurality of stator teeth 211 extending radially outward therefrom. Each stator tooth 211 is evenly spaced along the circumference of the stator core 21. The radial thickness of the tooth shoe of each stator tooth 211 is D, where D = 0.8 to 1.3 mm, and the shoulder inclination angle of each stator tooth 211 is b, where b = 110° to 115°. Since the height of the tooth tip (i.e., the aforementioned radial thickness of the tooth shoe) is relatively small, it is very easy to saturate. Moreover, the leakage magnetic path passes through the tooth tip, and the saturation position is mostly concentrated at the tooth tip. The aforementioned constraint relationship can ensure that the tooth tip height and angle (i.e., the aforementioned shoulder inclination angle) reach the optimal, preventing the tooth tip height from being too low or the angle from being too small, which would lead to tooth tip magnetic flux saturation and thus low utilization of permanent magnet materials. At the same time, it prevents the tooth tip height from being too high or the angle from being too large, which would lead to a reduction in the area of the stator slot and thus a reduction in slot utilization.
[0044] In some embodiments, a stator slot 212 is formed between two adjacent stator teeth 211, and a slot opening of the stator slot 212 is formed between two adjacent tooth shoes. The width of the slot opening is E, and E / D = 2.6 to 3.
[0045] In this technical solution, the aforementioned constraint relationship is used to optimize the slot width, preventing the slot width from being too large, which would lead to increased magnetic leakage, and preventing the slot width from being too small, which would lead to difficulties in heat dissipation and winding. In addition, under this constraint relationship, the air gap magnetic flux density waveform of the motor is closest to a sine wave, which helps to reduce the motor torque fluctuation, so as to achieve the best torque output and overall motor performance.
[0046] Please refer to the comparison. Figure 4 and Figure 5As shown, compared with the traditional external rotor hub motor that does not adopt the aforementioned technical solution of this utility model, the external rotor hub motor using the external rotor assembly and stator assembly of this utility model increases the maximum output torque from 79Nm to 89Nm, an increase of 12.7%, and reduces the torque ripple from 8.2% to 5.5%, a reduction of 33%, while ensuring that the material cost remains unchanged.
[0047] According to an embodiment of the present invention, an electric vehicle is also provided, including the aforementioned external rotor hub motor.
[0048] 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.
[0049] 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. An external rotor assembly, characterized in that, The system includes an outer rotor core (11). Multiple permanent magnets (12) are evenly spaced along the circumference of the inner circular wall of the outer rotor core (11). Each permanent magnet (12) has an inner sidewall (121) away from the inner circular wall and an outer sidewall (122) attached to the inner circular wall. The permanent magnet (12) also has a first sidewall connecting the first ends of the inner sidewall (121) and the outer sidewall (122), and a second sidewall connecting the second ends of the inner sidewall (121) and the outer sidewall (122). The first sidewall includes a first straight wall (1231) and a second straight wall (1232). The first end of the first straight wall (1231) is connected to the first end of the inner sidewall (121), and the second end of the first straight wall (1231) is connected to the first end of the second straight wall (1232). The second straight wall (1232) is connected to the first end of the outer wall (122) in a direction away from the inner circular wall surface, and the second straight wall (1232) is inclined toward the center of the circumferential length of the permanent magnet (12); and / or, the second sidewall includes a third straight wall (1241) and a fourth straight wall (1242), the first end of the third straight wall (1241) is connected to the second end of the inner wall (121), the second end of the third straight wall (1241) is connected to the first end of the fourth straight wall (1242), the second end of the fourth straight wall (1242) is connected to the second end of the outer wall (122), and the fourth straight wall (1242) is inclined toward the center of the circumferential length of the permanent magnet (12) in a direction away from the inner circular wall surface.
2. The external rotor assembly according to claim 1, characterized in that, Each of the permanent magnets (12) has a line of symmetry, and the first sidewall and the second sidewall are symmetrical about the line of symmetry.
3. The external rotor assembly according to claim 1 or 2, characterized in that, The radial distance between the inner wall (121) and the outer wall (122) is dc0. The first straight wall (1231) and the third straight wall (1241) both extend radially along the outer rotor core (11). The radial length of the first straight wall (1231) is dc1, dc1 / dc0 = 0.45~0.55; and / or, the radial length of the third straight wall (1241) is dc2, dc2 / dc0 = 0.45~0.
55.
4. The external rotor assembly according to claim 3, characterized in that, The angle between the radial extension of the first straight wall (1231) and the second straight wall (1232) is a1, a1 = 35° to 42°; and / or, the angle between the radial extension of the third straight wall (1241) and the fourth straight wall (1242) is a2, a1 = 35° to 42°.
5. The external rotor assembly according to claim 1, characterized in that, The inner sidewall (121) is concentric with the inner circular wall surface, and / or the outer sidewall (122) is concentric with the inner circular wall surface.
6. An external rotor hub motor, comprising an external rotor assembly (1) and a stator assembly located within an inner circular hole of an external rotor core (11) of the external rotor assembly (1), characterized in that, The external rotor assembly (1) is the external rotor assembly according to any one of claims 1 to 5.
7. The external rotor hub motor according to claim 6, characterized in that, The stator assembly includes a stator core (21) having a plurality of stator teeth (211) extending radially outward therefrom, each stator tooth (211) being evenly spaced along the circumference of the stator core (21), and the radial thickness of the tooth shoe of each stator tooth (211) being D, where D = 0.8 to 1.3 mm.
8. The external rotor hub motor according to claim 7, characterized in that, The tooth shoe shoulder inclination angle of each stator tooth (211) is b, where b = 110° to 115°.
9. The external rotor hub motor according to claim 8, characterized in that, A stator groove (212) is formed between two adjacent stator teeth (211), and a slot is formed between two adjacent tooth shoes. The width of the slot is E, and E / D = 2.6~3.
10. An electric vehicle, characterized in that, The invention includes the external rotor hub motor as described in any one of claims 6 to 9.