A hub motor with an outer rotor structure

Abstract

A hub motor with an outer rotor structure belongs to the field of motors. The present invention aims to solve the problems of poor connection between the motor housing and the rotor, resulting in poor roundness of the rotor and easy detachment of permanent magnets, which affect the performance of the motor. The hub motor of the present invention includes an outer rotor, an inner stator, and a housing. The outer rotor includes permanent magnets, a rotor core, and C-shaped connectors. P mounting grooves are evenly distributed along the circumferential direction on the inner circular surface of the housing. The C-shaped connectors assemble the rotor core inside the housing. The inner stator is arranged inside the outer rotor with a radial gap. P permanent magnet positioning teeth are evenly distributed along the circumferential direction on the inner circular surface of the rotor core. Permanent magnets are embedded between adjacent two permanent magnet positioning teeth in a mortise and tenon manner. The upper clamping ends of the P C-shaped connectors are respectively assembled with the P mounting grooves on the inner circular surface of the housing in a mortise and tenon manner. The lower clamping ends of the P C-shaped connectors are respectively fitted and assembled with the end parts of the P permanent magnet positioning teeth, and the P C-shaped connectors and the P permanent magnets are kept on the same roundness.

Description

Technical Field

[0001] The present invention relates to an assembly technology for an outer rotor and a housing of a wheel hub motor, belonging to the field of motors. Background Art

[0002] In order to cope with the increasingly severe global energy crisis and environmental pollution problems, the wheel hub motor technology, as one of the key technologies for new energy vehicles, has gradually become the future development direction of the automotive industry due to its advantages such as high transmission efficiency, compact structure, small volume, high power density, and high torque density. At the same time, due to the relatively thin thickness of the rotor and housing of the wheel hub motor, the traditional interference installation method and the special working environment make it easy to have problems such as poor connection and assembly between the relatively thin rotor and the housing of the wheel hub motor, poor roundness of the rotor, deformation of the rotor and the housing, eccentricity of the rotor, and poor vibration and noise. Summary of the Invention

[0003] Aiming at the problems of poor roundness of the rotor and easy detachment of the permanent magnet caused by the poor connection between the housing and the rotor of the wheel hub motor, which affect the performance of the motor, the present invention provides a wheel hub motor with an outer rotor structure.

[0004] The wheel hub motor with an outer rotor structure according to the present invention includes an outer rotor, an inner stator 5, and a housing 4. The outer rotor includes a permanent magnet 1, a rotor core 2, and a C-shaped connecting member 3. P mounting grooves are evenly distributed along the circumferential direction on the inner circular surface of the housing 4. The C-shaped connecting member 3 assembles the rotor core 2 inside the housing 4. The inner stator 5 is arranged inside the outer rotor, and there is a radial gap between them.

[0005] P permanent magnet positioning teeth 2-1 are evenly distributed along the circumferential direction on the inner circular surface of the rotor core 2. A permanent magnet 1 is embedded between two adjacent permanent magnet positioning teeth 2-1 in a mortise and tenon manner. The upper clamping ends of the P C-shaped connecting members 3 are respectively assembled with the P mounting grooves on the inner circular surface of the housing 4 in a mortise and tenon manner. The lower clamping ends of the P C-shaped connecting members 3 are respectively fitted and assembled with the end parts of the P permanent magnet positioning teeth 2-1, and the P C-shaped connecting members 3 and the P permanent magnets 1 are kept on the same roundness.

[0006] Preferably, the permanent magnet positioning teeth 2-1 of the rotor core 2 are strip-shaped structures extending axially, and the radial cross-section is two trapezoidal structures with the same bottom. Among them, the top side of the upper trapezoid is connected to the yoke part of the rotor core 2, with a size of A; the bottom side of the upper trapezoid coincides with the bottom side of the lower trapezoid, with a size of B, and the top side of the lower trapezoid is close to the air gap side, with a size of E, satisfying the relationship: A < B, E < B, and the distance from the top side of the lower trapezoid to the air gap side is F.

[0007] Preferably, the permanent magnet 1 is composed of a single permanent magnet block or multiple permanent magnet blocks arranged in parallel. The tangential dimension of the permanent magnet 1 at the rotor yoke side is G, and the tangential dimension of the permanent magnet 1 at the air gap side is H, satisfying the relationship: G > H, and the permanent magnet 1 and the adjacent two permanent magnet positioning teeth 2-1 form a mortise and tenon structure.

[0008] Preferably, the C-shaped connector 3 includes an upper clamping end 3-1, a lower clamping end 3-2 and an intermediate connector 3-3; the upper clamping end 3-1 and the lower clamping end 3-2 are axially extending strip structures. The radial cross-section of the upper clamping end 3-1 is a trapezoidal structure. The bottom side of the trapezoidal structure is on the side of the housing, with a size of I; the top side of the trapezoidal structure is on the side of the rotor core, with a size of N; the relationship is satisfied: I > N; the lower clamping end 3-2 is an axially extending strip structure, and the strip structure is a structure with a trapezoidal radial cross-section. The bottom side of the trapezoidal structure is on the side of the air gap, with a size of D; the top side of the trapezoidal structure is on the side of the rotor core, with a size of B; the relationship is satisfied: D > B; a limiting groove 3-4 with a trapezoidal cross-section is formed in the lower clamping end 3-2. The opening of the limiting groove 3-4 is located on the inner side surface of the lower clamping end 3-2. The trapezoidal bottom side of the limiting groove 3-4 is at the opening end, with a size of B, and the trapezoidal top side of the limiting groove 3-4 is at the bottom of the groove, with a size of E. The trapezoidal height of the limiting groove 3-4 is equal to the lower trapezoidal height of the permanent magnet positioning tooth 2-1. The limiting groove 3-4 is used to embed the strip structure where the lower trapezoid of the permanent magnet positioning tooth 2-1 is located.

[0009] Preferably, the housing 4 is made of aluminum alloy material.

[0010] Preferably, the dimensions of the P mounting grooves on the inner circular surface of the housing 4 match the upper clamping end 3-1 of the C-shaped connector 3, and the two form a mortise and tenon structure.

[0011] Preferably, the torque T of the motor includes an electromagnetic torque T e and a reluctance torque T r in two parts. The reluctance torque T r is obtained according to the following formula:

[0012]

[0013] In the formula, p is the number of pole pairs of the motor, L d is the direct-axis inductance, L q is the quadrature-axis inductance, I rms is the effective value of the rotor current of the motor, and β is the angle between the permanent magnet magnetic field and the rotor.

[0014] The beneficial effects of the present invention: The present invention provides a new assembly scheme, using a C-shaped connector to assemble the rotor core and the housing together and limit the permanent magnet. This assembly method can not only strengthen the connection between the rotor and the housing, effectively fix the permanent magnet, prevent the permanent magnet from falling off, prevent the rotor from deforming under harsh working conditions, improve the rotor stiffness, ensure the roundness, reduce the eccentricity risk, and ensure the stability of the hub operation, but also improve the torque and reduce the vibration and noise by using this structure. And it can further improve the torque of the in-wheel motor.

[0015] The present invention can conveniently fix the permanent magnet by fixing the permanent magnet on the rotor permanent magnet positioning groove. Compared with the traditional way of fixing the permanent magnet by gluing, the fixing method of the new structure is not easy to fall off, ensuring that the outer rotor of the in-wheel motor can work under more severe working conditions. Moreover, the protrusion of the positioning groove can utilize the reluctance torque that cannot be utilized by the traditional surface-mounted motor to further increase the torque. Through reasonable optimization by the EA evolutionary algorithm, the most suitable protrusion height is found to achieve the best performance, reduce magnetic leakage, and increase the torque.

[0016] Furthermore, on this basis, the permanent magnet, the outer rotor, and the housing are fixed together through a C-shaped structure, which not only provides better fixation to ensure the roundness of the outer rotor, reduces the possibility of eccentricity of the outer rotor, guarantees the stable operation of the motor, but also can improve the overall stiffness of the outer rotor, be able to reduce the deformation of the outer rotor caused by electromagnetic vibration, and reduce vibration noise, bringing a quieter driving environment for the driver of the vehicle.

[0017] The present invention realizes the characteristics of easy installation and firm installation during the installation process; ensures the stable operation of the motor during operation and reduces the risk of eccentricity; and has been improved in many aspects in terms of performance, increasing the torque and reducing vibration noise. Description of the Drawings

[0018] Figure 1 is an exploded view of an in-wheel motor with an outer rotor structure according to the present invention, without an inner stator;

[0019] Figure 2 is an exploded view of an in-wheel motor with an outer rotor structure according to the present invention, with an inner stator;

[0020] Figure 3 is a schematic structural diagram of the housing loaded with a C-shaped connecting piece;

[0021] Figure 4 is a schematic diagram of the process of assembling the permanent magnet and the rotor core into the housing;

[0022] Figure 5 is a schematic structural diagram of the permanent magnet, the rotor core, and the housing after assembly;

[0023] Figure 6 is at Figure 4 a schematic structural diagram of the housing after being cut in half on the basis, in the forward direction;

[0024] Figure 7 is at Figure 4 a schematic structural diagram of the housing after being cut in half on the basis, from another perspective;

[0025] Figure 8 is a schematic diagram of the process of assembling the rotor core and the permanent magnet using a C-shaped connecting piece;

[0026] Figure 9 It is a schematic structural diagram of the assembled rotor core and permanent magnet;

[0027] Figure 10 It is Figure 8 a partially enlarged view of

[0028] Figure 11 It is a dimension marking diagram of the rotor core after assembling the permanent magnet;

[0029] Figure 12 It is Figure 10 a dimension marking diagram of the permanent magnet positioning teeth part of the iron core in

[0030] Figure 13 It is Figure 10 a dimension marking diagram of the permanent magnet part in

[0031] Figure 14 It is a schematic diagram of the DQ axes under each pole of the rotor;

[0032] Figure 15 It is a schematic structural diagram of the C-type connecting piece;

[0033] Figure 16 It is a dimension marking diagram of the C-type connecting piece. Specific embodiments

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] Next, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments, but it is not a limitation of the present invention.

[0037] Specific embodiment 1: Next, in conjunction with Figures 1 to 16 this embodiment will be described. The hub motor with an outer rotor structure described in this embodiment includes an outer rotor, an inner stator 5 and a housing 4. The outer rotor includes a permanent magnet 1, a rotor core 2 and a C-type connecting piece 3. P mounting grooves are evenly distributed along the circumferential direction on the inner circumferential surface of the housing 4. The C-type connecting piece 3 assembles the rotor core 2 into the interior of the housing 4. The inner stator 5 is arranged inside the outer rotor, and there is a radial gap between the two;

[0038] On the inner circumferential surface of the rotor core 2, P permanent magnet positioning teeth 2-1 are evenly distributed along the circumferential direction. Between two adjacent permanent magnet positioning teeth 2-1, a permanent magnet 1 is inserted in a mortise and tenon manner. The upper clamping ends of the P C-shaped connectors 3 are respectively assembled with the P installation grooves on the inner circumferential surface of the housing 4 in a mortise and tenon manner. The lower clamping ends of the P C-shaped connectors 3 are respectively fitted and assembled with the end parts of the P permanent magnet positioning teeth 2-1, and the P C-shaped connectors 3 and the P permanent magnets 1 are kept on the same roundness.

[0039] The permanent magnet positioning teeth 2-1 of the rotor core 2 are axially extended strip structures, and the radial cross-section is two trapezoidal structures with the same bottom. Among them, the top side of the upper trapezoid is connected to the yoke part of the rotor core 2, and the dimension is A; the bottom side of the upper trapezoid coincides with the bottom side of the lower trapezoid, and the dimension is B, and the top side of the lower trapezoid is close to the air gap side, and the dimension is E, satisfying the relationship: A < B, E < B, and the distance from the top side of the lower trapezoid to the air gap side is F.

[0040] The permanent magnet 1 is composed of a single permanent magnet block or multiple permanent magnet blocks arranged in parallel. The tangential dimension of the permanent magnet 1 on the rotor yoke side is G, and the tangential dimension of the permanent magnet 1 on the air gap side is H, satisfying the relationship: G > H. The permanent magnet 1 and the adjacent two permanent magnet positioning teeth 2-1 form a mortise and tenon structure.

[0041] A permanent magnet positioning groove is formed between two permanent magnet positioning teeth 2-1. Due to the characteristic that the permanent magnet positioning groove is narrow on the air gap side, the fixation with the permanent magnet 1 is approximately a mortise and tenon structure, which can ensure that the two are closely combined together.

[0042] The C-shaped connector 3 includes an upper clamping end 3-1, a lower clamping end 3-2 and an intermediate connector 3-3; the upper clamping end 3-1 and the lower clamping end 3-2 are axially extended strip structures. The radial cross-section of the upper clamping end 3-1 is a trapezoidal structure, and the bottom side of the trapezoidal structure is on the housing side, and the dimension is I; the top side of the trapezoidal structure is on the rotor core side, and the dimension is N; satisfying the relationship: I > N; the lower clamping end 3-2 is an axially extended strip structure, and the strip structure is a trapezoidal structure in the radial cross-section. The bottom side of the trapezoidal structure is on the air gap side, and the dimension is D; the top side of the trapezoidal structure is on the rotor core side, and the dimension is B; satisfying the relationship: D > B; a limiting groove 3-4 with a trapezoidal cross-section is opened on the lower clamping end 3-2. The opening of the limiting groove 3-4 is located on the inner side surface of the lower clamping end 3-2. The trapezoidal bottom side of the limiting groove 3-4 is at the opening end, and the dimension is B. The trapezoidal top side of the limiting groove 3-4 is at the bottom of the groove, and the dimension is E. The trapezoidal height of the limiting groove 3-4 is equal to the lower trapezoidal height of the permanent magnet positioning tooth 2-1. The limiting groove 3-4 is used to embed the strip structure where the lower trapezoid of the permanent magnet positioning tooth 2-1 is located.

[0043] The intermediate connector 3-3 of the C-shaped connector 3 is connected to the tails of the upper clamping end 3-1 and the lower clamping end 3-2. The height dimension of the intermediate connector 3-3 is K, and the outer dimension and inner dimension of the radial lengths of the upper clamping end 3-1 and the lower clamping end 3-2 are M and L respectively.

[0044] The C-shaped connecting piece 3 serves to ensure roundness and reduce vibration noise. The lower clamping end 3-2 of the C-shaped connecting piece 3 clamps on the permanent magnet positioning teeth 2-1 of the rotor core 2, and the upper clamping end 3-1 is located on the housing 4. The P mounting grooves on the inner circular surface of the housing 4 are dimensioned to match the upper clamping end 3-1 of the C-shaped connecting piece 3, and the two form a mortise and tenon structure, which can tightly fix the rotor core 2 and the housing 4.

[0045] The housing 4 is made of aluminum alloy. This material has high stiffness and is not easily deformed. Coupled with the tight fixation with the rotor core, the rotor is also not easily deformed.

[0046] The rotor structure described in this embodiment can not only be tightly combined but also increase the torque. The principle is to utilize the reluctance torque of the motor. The torque source of the motor can be divided into two parts, electromagnetic torque and reluctance torque. For a general surface-mounted rotor, the torque source is only electromagnetic torque and the reluctance torque is not utilized. The feature of the present invention is that the protruding permanent magnet positioning teeth on the outer rotor can generate reluctance torque, and the torque is increased compared with that of a surface-mounted permanent magnet motor.

[0047] The reluctance torque stems from the inconsistency of the D-axis and Q-axis reluctances in the magnetic circuit. In a permanent magnet synchronous motor, since the magnetic flux always prefers to take the path with the least reluctance, the inconsistency of the reluctances of the two axes causes the magnetic flux to be biased in path selection. Under the condition of the same current, the greater the difference in DQ-axis reluctances, the greater the reluctance torque. Since the magnetic permeability of the permanent magnet is basically the same as that of the air gap, and the magnetic permeability of the iron core is much greater than that of the air, the magnetic flux mostly passes through the iron core. Due to the existence of the permanent magnet positioning slots in the present invention, there are two parts, the permanent magnet and the air gap, on the direct axis, and only the air gap on the quadrature axis, resulting in the inconsistency of the quadrature-axis reluctance and the direct-axis reluctance, and generating the reluctance torque.

[0048] The torque T of the motor includes the electromagnetic torque T e and the reluctance torque T r in two parts. The reluctance torque T r is obtained according to the following formula:

[0049]

[0050] In the formula, p is the number of pole pairs of the motor, L d is the direct-axis inductance, L q is the quadrature-axis inductance, I rms is the effective value of the rotor current of the motor, and β is the angle between the permanent magnet magnetic field and the rotor.

[0051] The torque of the motor is divided into two parts. The first part is the electromagnetic torque, and the second part is the reluctance torque. The reluctance torque comes from the difference between the D-axis reluctance and the Q-axis reluctance. The greater the difference, the greater the additional reluctance torque. In other words, the longer the protruding length of the permanent magnet positioning tooth 2-1, the greater the additional reluctance torque. However, in the present invention, the protruding length of the tooth is not made the longest to be flush with the height of the permanent magnet, but is slightly shorter than the height F of the permanent magnet. The reason is that too long a protruding length will cause a relatively serious magnetic leakage phenomenon in the motor, which will instead reduce the torque. The shape of the protruding tooth is optimized by the EA evolutionary algorithm to find the optimal shape, which is the shape of the present invention, to maximize the torque and reduce magnetic leakage.

[0052] As a further improvement measure of the present invention, in order to solve the problems of poor rotor roundness and large vibration noise, a C-shaped connecting piece 3 is proposed. This structure is located between the machine shell 4 and the rotor core 2 to play a fixing role. The shape of the lower clamping end 3-2 of the C-shaped connecting piece 3 is the same as the shape of the lower trapezoid of the permanent magnet positioning tooth 2-1. The lower clamping end 3-2 can cooperate with the permanent magnet positioning tooth 2-1 to ensure that the roundness of the outer rotor will not be affected by external actions and will not change the stable operation of the motor due to changes in the external environment, reducing the risk of motor eccentricity and being beneficial to the smooth operation of the motor.

[0053] The motor vibration is judged by the following formula:

[0054]

[0055] In the formula, Y1 and Y2 are the vibration displacements of the rotor core and the machine shell in the motor respectively, Pn is the concentrated force causing the motor vibration, where K1 and K2 are the stiffnesses of the motor rotor core and the machine shell respectively, m1 and m2 are the masses of the rotor core and the machine shell respectively, and ω is the frequency of the concentrated force causing the motor vibration. It can be seen from the formula that the greater the stiffness and the smaller the mass, the smaller the vibration displacement of the motor. Among them, the stiffness usually refers to the ability to resist deformation, that is, a proportional coefficient between force and displacement. The size of the stiffness depends on the geometric shape and material type of the part. The greater the stiffness of the outer rotor, the stronger the anti-deformation ability of the motor and the better the vibration reduction and noise reduction effect.

[0056] From the above formula, it is obtained that the material of the C-shaped connecting piece 3 cannot be magnetic (to prevent a more serious magnetic leakage phenomenon), and it is required to have characteristics such as a large Young's modulus, a small Poisson's ratio, and a small density. The above characteristics are to improve the stiffness of the outer rotor. In this embodiment, the C-shaped connecting piece 3 is made of aluminum alloy material, which can meet the above characteristics and is easy to process, assemble and produce. Therefore, the addition of the C-shaped connecting piece 3 can achieve the effect of reducing vibration noise.

[0057] Assembly method of this embodiment: First, the permanent magnet 1 can be installed on the rotor core 2 to achieve a tight fit similar to a mortise-and-tenon structure. Then, the lower clamping end 3-2 of the C-shaped connecting piece 3 is inserted onto the permanent magnet positioning teeth 2-1 on the rotor 2 between the permanent magnets 1 to further tightly fix the permanent magnet 1 and the rotor core 2. Finally, the upper clamping end 3-1 of the C-shaped connecting piece 3 is inserted into the installation groove of the machine housing from the tail to achieve a tight fit similar to a mortise-and-tenon structure with the machine housing 4, completing the installation.

[0058] Alternatively, the upper clamping end 3-1 of the C-shaped connecting piece 3 can be inserted into the installation groove of the machine housing from the tail first, and then the rotor core is inserted into the C-shaped connecting piece 3, so that the permanent magnet positioning teeth 2-1 are inserted into the limiting groove 3-4 of the lower clamping end 3-2 of the C-shaped connecting piece 3.

[0059] The assembly sequence is relatively arbitrary and the assembly is easy.

[0060] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A hub motor with an outer rotor structure, characterized in that The in-wheel motor includes an outer rotor, an inner stator (5) and a housing (4). The outer rotor includes a permanent magnet (1), a rotor core (2) and a C-shaped connecting piece (3). The inner circumferential surface of the housing (4) is evenly distributed with P mounting grooves along the circumferential direction. The C-shaped connecting piece (3) assembles the rotor core (2) inside the housing (4). The inner stator (5) is arranged inside the outer rotor, and there is a radial gap between them. The inner circumferential surface of the rotor core (2) is evenly distributed with P permanent magnet positioning teeth (2-1) along the circumferential direction. A permanent magnet (1) is inserted between two adjacent permanent magnet positioning teeth (2-1) in a mortise and tenon manner. The upper clamping ends of the P C-shaped connecting pieces (3) are respectively assembled with the P mounting grooves on the inner circumferential surface of the housing (4) in a mortise and tenon manner. The lower clamping ends of the P C-shaped connecting pieces (3) are respectively fitted and assembled with the ends of the P permanent magnet positioning teeth (2-1), and the P C-shaped connecting pieces (3) and the P permanent magnets (1) are kept on the same roundness. The permanent magnet positioning teeth (2-1) of the rotor core (2) are axially extending strip-shaped structures, and the radial cross-section is two trapezoidal structures with the same bottom. The top side of the upper trapezoid is connected to the yoke part of the rotor core (2), and the dimension is A. The bottom side of the upper trapezoid coincides with the bottom side of the lower trapezoid, and the dimension is B. The top side of the lower trapezoid is close to the air gap side, and the dimension is E, satisfying the relationship: A < B, E < B. The distance from the top side of the lower trapezoid to the air gap side is F. The permanent magnet (1) is composed of a single permanent magnet block or multiple permanent magnet blocks arranged in parallel. The tangential dimension of the rotor yoke side of the permanent magnet (1) is G, and the tangential dimension of the air gap side of the permanent magnet (1) is H, satisfying the relationship: G > H. The permanent magnet (1) and the adjacent two permanent magnet positioning teeth (2-1) form a mortise and tenon structure. The C-shaped connecting piece (3) includes an upper clamping end (3-1), a lower clamping end (3-2) and an intermediate connecting piece (3-3). The upper clamping end (3-1) and the lower clamping end (3-2) are axially extending strip-shaped structures. The radial cross-section of the upper clamping end (3-1) is a trapezoidal structure. The bottom side of the trapezoidal structure is on the housing side, and the dimension is I. The top side of the trapezoidal structure is on the rotor core side, and the dimension is N, satisfying the relationship: I > N. The lower clamping end (3-2) is an axially extending strip-shaped structure, and the strip-shaped structure is a trapezoidal structure in the radial cross-section. The bottom side of the trapezoidal structure is on the air gap side, and the dimension is D. The top side of the trapezoidal structure is on the rotor core side, and the dimension is B, satisfying the relationship: D > B. A limiting groove (3-4) with a trapezoidal cross-section is opened in the lower clamping end (3-2). The opening of the limiting groove (3-4) is located on the inner side surface of the lower clamping end (3-2). The trapezoidal bottom side of the limiting groove (3-4) is at the opening end, and the dimension is B. The trapezoidal top side of the limiting groove (3-4) is at the bottom of the groove, and the dimension is E. The trapezoidal height of the limiting groove (3-4) is equal to the lower trapezoidal height of the permanent magnet positioning tooth (2-1). The limiting groove (3-4) is used to embed the strip-shaped structure where the lower trapezoid of the permanent magnet positioning tooth (2-1) is located.

2. The hub motor with an outer rotor structure according to claim 1, wherein The housing (4) is made of aluminum alloy material.

3. The hub motor with an outer rotor structure according to claim 1, characterized in that, The dimensions of the P mounting grooves on the inner circumferential surface of the housing (4) match the upper clamping end (3-1) of the C-shaped connecting piece (3), and the two form a mortise and tenon structure.

4. The hub motor with an outer rotor structure according to claim 1, wherein The torque T of the motor includes the electromagnetic torque T e and the reluctance torque T r The reluctance torque T r is obtained according to the following formula: where p is the number of pole pairs of the motor, L d is the direct-axis inductance, L q is the quadrature-axis inductance, I rms is the effective value of the rotor current of the motor, and β is the angle between the permanent magnet magnetic field and the rotor.

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