CN111525714A

CN111525714A - Motor and stator core thereof

Info

Publication number: CN111525714A
Application number: CN202010529660.4A
Authority: CN
Inventors: 罗宁; 王安; 陈丹枫
Original assignee: Ningbo Saijia Electromechanical Co ltd
Current assignee: Ningbo Saijia Electromechanical Co ltd
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2020-08-11

Abstract

The invention provides a motor and a stator core thereof, wherein the stator core comprises an outer peripheral wall and two winding teeth, the winding teeth are oppositely arranged on the inner side of the outer peripheral wall, the outer peripheral wall is U-shaped, the outer peripheral wall comprises a winding part, the winding part is positioned on the side of the two winding teeth, the winding part and the two winding teeth are wound to generate a magnetic field, and the magnetic field of the winding part is transmitted to the two winding teeth to enhance the magnetic field at the two winding teeth.

Description

Motor and stator core thereof

Technical Field

The invention relates to the technical field of motors, in particular to a motor and a stator core thereof.

Background

The motor has wide application in the field of electric appliances. With the improvement of the social living standard, small electric appliances such as electric toothbrushes and electric beauty instruments are favored by more and more consumers. The working parts of such small electric appliances need to be driven by a motor to reciprocate for cleaning, massaging, etc. The angle, distance, frequency, stability, etc. of the reciprocating motion of the working member have an influence on the working effect. The performance of the motor is decisive for the working effect of the working parts. The unilateral winding of U type iron core, the magnetic field that produces is limited, in order to ensure the effect of exerting oneself of motor, U type iron core needs to have sufficient volume for enough coils of winding.

Referring to fig. 1, a stator core 10P of a conventional motor is schematically shown, the stator core 10P includes a winding portion 11P and two side portions 12P, and the winding portion 11P and the two side portions 12P are integrally formed. An opening 100P is formed between the two side portions 12P. The winding portion 11P and the two side portions 12P surround to form a hollow accommodating space. The stator core 10P is U-shaped. The side portion 12P has an inner surface 121P, and the inner surface 121P is a plane. The enamel wire is wound to the winding portion 11P. The rotor passes through the housing space of the stator core 10P. The stator core 10P is wound on one side, and the energy of the magnetic field that can be generated is limited.

In addition, since the inner surface 121P of the side portion 12P is a plane, the air gap between the side portion 12P and the rotor is not uniform, which affects the force effect of the rotor. The suction force generated by the inner side of the side portion 12P to the two sides of the rotor is unbalanced, and the suction force cannot be centered effectively, so that energy is consumed in centering during movement, and the output effect of the rotor is also influenced.

In addition, the rotor has a complex structure and multiple processes, and parts such as a rotating shaft, a magnetic conduction plate and the like need to be processed through plastic parts or injection molding processes, so that the rotor cannot be automatically processed effectively, and the production efficiency is low.

Disclosure of Invention

An advantage of the present invention is to provide a motor and a stator core thereof, in which winding positions of the motor are increased to enhance a force effect.

Another advantage of the present invention is to provide an electric machine and a stator core thereof, in which both sides of a rotor of the electric machine are effectively centered, reducing power consumption for rotational position correction.

Another advantage of the present invention is to provide an electric motor and a stator core thereof, in which the stator includes a stator core, and at least two winding teeth are oppositely disposed at an inner side of the stator core to increase winding positions and enhance a magnetic field that can be generated.

Another advantage of the present invention is to provide a motor and a stator core thereof, in which the winding sets are distributed relatively to each other, so as to enhance the magnetic field and improve the output effect of the rotor.

Another advantage of the present invention is to provide an electric machine and a stator core thereof, in which air gaps between inner surfaces of the winding teeth of the stator core and outer surfaces of the magnets of the rotor are uniformly distributed, thereby enhancing a force output effect of the rotor.

Another advantage of the present invention is to provide a motor and a stator core thereof, in which the rotor does not have a plastic member, thereby eliminating the injection molding process and facilitating the automatic processing.

Another advantage of the present invention is to provide a motor and a stator core thereof, in which a portion of a circumferential wall of a housing of the motor has a planar outer surface to be adapted to mount a flat member on an outer side, reducing an occupied space.

Additional advantages and features of the invention will be set forth in the detailed description which follows and in part will be apparent from the description, or may be learned by practice of the invention as set forth hereinafter.

In accordance with one aspect of the present invention, the foregoing and other objects and advantages are achieved by a stator core of the present invention, comprising:

an outer peripheral wall and two wire winding teeth, the wire winding tooth is set up in the inboard of outer peripheral wall relatively, the outer peripheral wall is the U type, wherein the outer peripheral wall includes a wire winding portion, the wire winding portion is located two the wire winding tooth side, wire winding portion and two the wire winding tooth are wound, in order to produce magnetic field, wherein the magnetic field of wire winding portion is passed to two the wire winding tooth, in order to strengthen the magnetic field of two the wire winding tooth department.

According to an embodiment of the present invention, the stator core further includes two side portions, the side portion, the winding portion and the other side portion are connected in sequence to form the U-shaped outer circumferential wall, wherein the two winding teeth are respectively disposed on the two side portions and are opposite to each other.

According to an embodiment of the present invention, each of the two winding teeth includes a protruding portion and two latching portions, each of the protruding portions is formed by extending from an inner side of the two side portions in a protruding manner, and each of the latching portions is formed by bending from an end portion of the protruding portion close to a center side of the stator core to two sides, so that each of the two winding teeth forms an arc-shaped inner surface.

According to another aspect of the present invention, there is further provided a motor comprising:

a rotor; and

a stator, the rotor is installed in the inner side of the stator, wherein the stator comprises a stator core, the stator core comprises an outer peripheral wall and two winding teeth, the winding teeth are oppositely arranged in the inner side of the outer peripheral wall, the outer peripheral wall is U-shaped, wherein the outer peripheral wall comprises a winding part, the winding part is positioned on the side between the two winding teeth, the winding part and the two winding teeth are wound to generate a magnetic field, and the magnetic field of the winding part is transmitted to the two winding teeth to enhance the magnetic field at the two winding teeth.

According to an embodiment of the present invention, each of the two winding teeth includes a protrusion and two detents, the protrusions are formed by extending from the inner side of the outer circumferential wall in a protruding manner, and the detents are formed by bending from the end of the protrusion near the center of the stator core to two sides, so that the two winding teeth form an arc-shaped inner surface.

According to one embodiment of the present invention, the rotor includes a rotor core, a driving shaft passing through the rotor core, and at least two magnets, the rotor core has at least two mounting grooves disposed back to back, and the magnets are respectively mounted in the mounting grooves.

According to one embodiment of the present invention, an outer surface of the magnet facing the inner surface of the stator core is a curved surface, and air gaps between the outer surface of the magnet and the inner surface of the stator core are uniformly distributed.

According to an embodiment of the present invention, the motor further includes at least one winding group, the winding group is wound to the two winding teeth and the winding portion, and the two winding teeth and the winding group of the winding portion are connected.

According to an embodiment of the present invention, the stator further includes at least two bobbins, each of the bobbins is installed at both ends of the stator core, respectively, the shape of the bobbin is adapted to the U shape of the outer circumferential wall and the two winding teeth, and the winding groups are wound along the bobbins, the two winding teeth, and the winding part.

According to one embodiment of the present invention, the bobbin includes at least two connecting teeth via which the winding teeth, the winding portion, and the winding groups at the other winding teeth are connected.

According to an embodiment of the present invention, the motor further includes a housing installed outside the stator, and a cover body covered at one end of the housing to close the stator.

According to an embodiment of the present invention, the housing includes a first peripheral wall and a second peripheral wall, the first peripheral wall and the second peripheral wall being connected to form the peripheral wall of the housing, wherein the shape of the first peripheral wall is adapted to the shape of the peripheral wall, the second peripheral wall is opposed to an opening position of the peripheral wall of the stator core, and the second peripheral wall extends straight so as to have a planar outer surface.

According to one embodiment of the invention, at least two bearings are connected between the housing and the drive shaft, the bearings being respectively arranged at both ends of the housing and connected to the drive shaft for supporting the movement of the drive shaft.

Further objects and advantages of the invention will be fully apparent from the ensuing description and drawings.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

Fig. 1 is a schematic view of a stator core of an electric machine according to the prior art.

Fig. 2 is a schematic view of a stator core according to a preferred embodiment of the present invention.

Fig. 3 is a perspective view of a motor according to a preferred embodiment of the present invention.

Fig. 4 is an exploded view of a motor according to a preferred embodiment of the present invention.

Fig. 5 is a schematic cross-sectional view of an electric machine according to a preferred embodiment of the invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be in a particular orientation, constructed and operated in a particular orientation, and thus the above terms are not to be construed as limiting the present invention.

It is understood that the terms "a" and "an" should be interpreted as meaning that a number of one element or element is one in one embodiment, while a number of other elements is one in another embodiment, and the terms "a" and "an" should not be interpreted as limiting the number.

Referring to the drawings of fig. 2 to 5 in the specification of the present invention, an electric motor and a stator core thereof according to a preferred embodiment of the present invention are disclosed and described in the following description.

Fig. 2 shows a stator core 11, the stator core 11 comprising an outer peripheral wall 111 and two winding teeth 112, the outer peripheral wall 111 being U-shaped. The two winding teeth 112 are oppositely disposed inside the outer peripheral wall 111. The outer peripheral wall 111 includes a winding portion 1111 and two side portions 1112. The side portion 1112, the winding portion 1111 and the other side portion 1112 are connected in this order to form the U-shaped outer peripheral wall 111. The winding portion 1111 is used for winding a winding group.

An opening 1110 of the outer peripheral wall 111 is formed between the ends of the side portions 1112.

The two side portions 1112 are oppositely disposed. The two winding teeth 112 are oppositely disposed on the inner side of the side portion 1112, and the end portions of the two winding teeth 112 are opposite.

The two winding portions 112 respectively include a protrusion portion 1121 and two retaining portions 1122, and the two protrusion portions 1121 are formed by protruding and extending from the inner sides of the two side portions 1112. The two latching portions 112 of each of the protrusions 1121 are formed by extending from the protrusion 1121 toward the middle end of the stator core 11 and bending the protrusion to both sides. The two positioning portions 112 are bent toward the middle of the stator core 11 to form an inner surface 1123 at the end of the two winding teeth 112 facing the middle of the stator core 11, and the inner surface 1123 is an arc surface. A receiving space is formed between the inner surfaces 1123 for receiving a rotor.

The connection position between the protrusion 1121 and the side portion 1112 may be an end portion of the side portion 1112, or may be another position of the side portion 1112.

The protrusion 1121 may be used for winding a winding set, and the locking portion 1122 serves to limit the winding set, so as to prevent the winding set from falling off, so that the magnetic field at the winding teeth 112 is stable.

The winding portion 1111 and the two winding teeth 112 can be wound with wire. That is, the stator core 11 is a three-side wound core. Two winding teeth 112 are additionally arranged on the inner side of the U-shaped outer peripheral wall 111 to increase the winding positions and the number of the stator cores 11. When the stator core 11 is energized, the magnetic energy generated at the winding portion 1111 is transferred to the two winding teeth 112 to enhance the magnetic field at the two winding teeth 112. Thereby enhancing the output effect of the motor in which the stator core 11 is assembled.

When the volume of the stator core 11 is not changed, the winding position and the winding amount of the stator core 11 are increased, so that the magnetic field generated by the stator core 11 is enhanced, and the output effect of a motor assembled with the stator core 11 is enhanced.

And under the condition that the output of the motor is not changed, the size of the stator core 11 can be smaller, the structure is more compact, and the space utilization rate is improved. The magnetic field of the stator core 11 is enhanced by increasing the winding position and the winding amount, so that the same force effect can be realized, and the volume of the stator core 11 can be reduced. The whole volume of the motor can be reduced, the cost is reduced, and the design and the arrangement of other components of the product are convenient.

In addition, by additionally arranging the winding teeth in the stator core 11 and setting the surfaces of the winding teeth to be cambered surfaces, air gaps between the stator and the rotor are uniform, and the output effect of the rotor is enhanced. The winding teeth are oppositely arranged, so that relative suction is generated to the rotor, the rotor is kept centered, and the rotation position of the rotor is automatically corrected.

Referring to fig. 3 to 5, the present invention further provides a motor and a stator core thereof, the motor being assembled with the stator core 11. Specifically, the motor includes a stator 10 and a rotor 20, and the stator 10 is sleeved outside the rotor 20. The rotor 20 is inserted inside the stator 10. The rotor 20 moves in the center of the stator 10. Preferably, the central axis of the rotor 20 and the central axis of the stator 10 coincide. The stator 10 is electrified to generate a magnetic field, and the rotor 20 is driven to vibrate under the action of magnetic force. Further, the stator 10 drives the rotor 20 to oscillate. The rotor 20 is reciprocally rotated by a certain angle.

The motor further includes a housing 30 and at least one cover 40, wherein the housing 30 is mounted outside the stator 10 to cover the stator 10. The cover 40 is covered at one end of the housing 30, and encloses the stator 10 together with the housing 30. The central axes of the stator 10, the rotor 20 and the housing 30 coincide.

The stator 10 includes the stator core 11, a first bobbin 12 and a second bobbin 13, and the first bobbin 12 and the second bobbin 13 are respectively installed at both ends of the stator core 11. The first bobbin 12 and the second bobbin 13 are made of an insulating material. The stator core 11 may be formed by laminating and punching a plurality of silicon steel sheets in a direction parallel to the central axis thereof.

The shape of the first bobbin 12 and the second bobbin 13 is adapted to the shape of the stator core 11 to fit the U-shaped outer peripheral wall 111 and the two winding teeth 112.

The first bobbin 12 and the second bobbin 13 are respectively provided with at least two connecting teeth 15, the connecting teeth 15 allow the winding group 14 to pass through or wind, and after the first bobbin 12 and the second bobbin 13 are mounted on the stator core 11, the connecting teeth 15 are respectively located between the winding teeth 112 and the winding portion 1111. The winding group 14 at the winding tooth 112 may be connected via the connecting tooth 15 and the winding group 14 at the winding portion 1111. The connecting teeth 15 support the winding set 14 on the first bobbin 12 and the second bobbin 13, so as to prevent the winding set 14 from suspending in the stator 10 and the rotor 20, and prevent the displacement of the winding set 14 from interfering with the motion of the motor.

The stator 10 further includes at least one winding group 14, and the winding group 14 is wound to two winding teeth 112 and the winding portion 1111. The winding teeth 112 and the winding portion 1111 may be wound around the winding groups 14, respectively, and then the winding groups 14 may be connected. The winding group 14 may be wound along the winding tooth 112, the winding portion 1111 and the other winding tooth 112 in sequence.

The stator core 11 is three-side wound to enhance a magnetic field generated after power is applied.

The rotor 20 is inserted between the winding teeth 112, and the winding teeth 112 are symmetrically distributed on the outer circumference of the rotor 20.

The two winding teeth 112 are oppositely distributed on the stator core 11, and generate opposite suction force to the rotor 20 arranged between the winding teeth, so that the rotor 20 is centered under the action of the suction force, and the rotating position of the rotor 20 is corrected.

The detent portions 1122 are symmetrically arranged, and two ends of the detent portions 1122 generate symmetric suction forces on the side surfaces of the rotor 20, so that the side surfaces of the rotor 20 are uniformly and centrally stressed. The two side surfaces of the rotor 20 respectively receive the symmetric suction force of the retention portions 1122 of the two winding teeth 112, and the two side surfaces of the rotor 20 are respectively centered with respect to the two winding teeth 112, so that the centering effect of the rotor 20 is good, which is beneficial to enhancing the output effect of the motor.

The rotor 20 is attached to an accommodating space between the locking portions 1122, and the rotor 20 moves in the accommodating space. When the winding groups 14 are energized, a magnetic force is generated between the winding groups 14 and the magnets 23 of the rotor 20, so that the driving shaft 21 is vibrated.

By arranging the winding teeth 112 in the stator core 11, the winding positions and the number of windings of the winding groups 14 are increased, so that the magnetic field is enhanced, and the output effect of the motor is improved. The symmetrical arrangement of the winding teeth 112 allows the rotor 20 to be subjected to symmetrical suction forces, and the rotor 20 is centered under both side forces. Further, the lateral surfaces of the two sides of the rotor 20 are respectively subjected to symmetrical suction forces, so that the lateral surfaces of the two sides of the rotor 20 are respectively centered with respect to the two winding teeth 112.

The outer peripheral wall 111 of the stator core 11 is provided with the opening 1110, so that the material of which the outer peripheral wall 111 is made is reduced, reducing the cost of manufacturing the outer peripheral wall 111. When the stator 10 is wound, the opening 1110 provides a larger space for the winding operation, and reduces the winding difficulty.

The housing 30 includes a first peripheral wall 31 and a second peripheral wall 32, and the first peripheral wall 21 and the second peripheral wall 32 are connected to form the peripheral wall of the housing 30. The shape of the first peripheral wall 31 is adapted to the shape of the peripheral wall 111 of the stator core 11. The first peripheral wall 32 is substantially U-shaped or nearly U-shaped. The second peripheral wall 32 is located opposite to the opening 1110 of the stator core 11. The second peripheral wall 32 extends flat so as to have a planar outer surface adapted to mount a circuit board or the like flat member on the outer side of the second peripheral wall 32. The second peripheral wall 32, which is a flat surface, reduces the amount of space occupied relative to the curved surface, making the motor more compact and providing more space for assembly on the outside of the motor.

The rotor 20 includes a driving shaft 21, a rotor core 22, and at least two magnets 23, and the rotor core 22 and the magnets 23 are mounted to the driving shaft 21. The magnets 23 are symmetrically mounted to the rotor core 22. In other examples of the present invention, the rotor 21 includes a drive shaft 21 and a magnet 23, and the magnet 23 is mounted to the drive shaft 21. The number of the magnets 23 is not limited.

In another example of the present invention, the rotor core 22 may be the magnet 23.

Each of the magnets 23 has an outer surface 231 on both sides facing the rotor 20. The two outer surfaces 231 are outer surfaces of both sides of the rotor 20. The outer surface 231 is a curved surface.

When the rotor 20 and the stator 10 are assembled, the two outer surfaces 231 face the two inner surfaces 1123 of the winding teeth 112, respectively. The outer surface 231 and the inner surface 1123 are both arc surfaces with the same spacing therebetween, so that the air gap between the stator 10 and the rotor 20 is uniformly distributed. The uniform air gap ensures that the motor runs stably, the energy consumption is lower, and the output effect is strong. In addition, the outer surface 231 of the rotor 20 is processed into a cambered surface, so that an air gap between the rotor 20 and the stator 10 is reduced, current consumption is reduced, and motor power is improved.

Both sides of the rotor 20 are stressed and are respectively subjected to the symmetrical suction forces generated by the two winding teeth 112. Under the action of the suction force, the rotor 20 is automatically corrected in rotation position, so that the rotor 20 is kept in a centered state.

The housing 30 is installed at the outside of the stator 10 to wrap the stator 10. The cover 40 is mounted to one end of the housing 30 to close the housing 30.

The motor further comprises at least two bearings 24. One end of the driving shaft 21 extends to the outside of the stator 10, passes through the cover 40, and extends to the outside of the cover 40. At least one bearing 24 is installed between the cover body 40 and the stator 10, and one end of the driving shaft 21 passes through the bearing 24 to be rotatably coupled to the cover body 40. One end of the drive shaft 21 extends through the housing 30 to the outside of the housing 30. The other bearing 24 is installed at an outer end of the housing 30, and one end of the driving part 21 passes through the bearing 24 and is rotatably connected to the housing 30.

In an example of the present invention, the rotor 20 is not provided with plastic parts, so that an injection molding process can be omitted during the processing of the rotor 20, which facilitates the automatic processing of the rotor 20 and reduces the manufacturing cost. Will rotor core 22 is fixed to drive shaft 21, will magnet 23 fixed value rotor core 22 avoids using the working of plastics to carry out the connection of magnetic conduction board and pivot, drive shaft 21 forms a whole to adopt automatic processing technology directly with rotor core 22 with magnet 23 processing extremely drive shaft 21, production efficiency is high, reduces technology cost. Plastic parts are omitted from the rotor 20, so that the rotor 20 is made of metal materials and magnetic materials integrally and is stable in performance.

Further, fig. 5 shows a motion state of the motor, for example, the upper and lower ends of the magnet 23 are respectively an S pole and an N pole. When the 14 is powered on and generates a current in one direction, an N pole and an S pole are generated on the two winding teeth 112 respectively. The N pole and the N pole repel each other to generate thrust, and the N pole and the S pole attract each other to generate attraction, so that the rotor 20 rotates counterclockwise under the magnetic force. The winding portion 1111 is wound around the winding group 14 to generate a magnetic field after being energized, and the magnetic field transmitted to the two winding teeth 112 through the winding group 14 is communicated to respectively enhance the N pole and the S pole at the two winding teeth 112 at two sides, so that the suction force and the thrust force to the rotor 20 are also enhanced, and the force effect of the rotor 20 is improved.

When the winding group 14 is energized with the current in the opposite direction, the S pole and the N pole are generated at the left winding tooth and the right winding tooth, respectively, and the magnetic field at the winding portion 1111 is transferred to the magnetic field at the two winding teeth 112, so as to enhance the S pole and the N pole at the two winding teeth 112 at the two sides. Under magnetic force, the rotor 20 rotates clockwise.

When the winding group 14 is not energized, the outer surfaces 231 on both sides of the rotor 20 are respectively attracted by the inner surfaces 1131 of the winding teeth. The air gap between the rotor 20 and the stator core 11 is uniform, and the stress is balanced, so that the outer surface 231 is centered relative to the inner surface 1131, and both sides of the rotor 20 are respectively centered, thereby maintaining the centered state of the whole rotor 20.

Under the condition that the output effect of the rotor 20 is not changed, the whole volume of the stator 10 can be smaller, and the winding part of the stator 10 is increased, so that the magnetic field generated after the stator 10 is electrified is enhanced, the output effect of the rotor 20 is further ensured, and the motor can be smaller in volume and more compact in structure on the premise of ensuring the performance of the motor.

And under the same volume, the winding position of the stator 10 is increased, the generated magnetic field is enhanced, the output effect of the rotor 20 is improved, and the motor has better performance.

The motor provided by the invention can be applied to various small-sized electric appliances such as electric toothbrushes, facial cleaning instruments, massage instruments and the like, provides stable kinetic energy for the working parts of the electric appliances and ensures good working effect.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. A stator core, comprising:

2. The stator core according to claim 1, wherein said stator core further comprises two side portions, said side portion, said winding portion and another said side portion being connected in sequence to form said outer peripheral wall having a U-shape, wherein two said winding teeth are respectively disposed on two said side portions and are located oppositely.

3. The stator core according to claim 2, wherein each of the two winding teeth includes a protrusion and two engaging portions, each of the protrusions is formed by extending from an inner side of the two side portions in a protruding manner, and each of the engaging portions is formed by bending from an end portion of the protrusion near a center side of the stator core to both sides, so that each of the two winding teeth forms an inner surface of an arc shape.

4. An electric machine, comprising

A rotor; and

5. The electric machine according to claim 4, wherein the stator core further comprises two side portions, the side portion, the winding portion and the other side portion being connected in sequence to form the outer peripheral wall of the U-shape, wherein two winding teeth are respectively provided at the two side portions in opposite positions.

6. The stator core according to claim 5, wherein each of the two winding teeth includes a protrusion and two detents, the protrusions are formed to protrude from an inner side of the outer circumferential wall, and the detents are formed to be bent from ends of the protrusions near a center of the stator core to both sides, so that each of the two winding teeth forms an arc-shaped inner surface.

7. The stator core of claim 6 wherein said rotor includes a rotor core, a drive shaft extending through said rotor core, and at least two magnets, said rotor core having at least two mounting slots disposed in a back-to-back relationship, each of said magnets being mounted in said mounting slots.

8. The electric machine of claim 7 wherein an outer surface of said magnet facing said inner surface of said stator core is a curved surface, and wherein air gaps between said outer surface of said magnet and said inner surface of said stator core are evenly distributed.

9. The electric machine according to claim 4, wherein said electric machine further comprises at least one winding group, said winding group being wound to two said winding teeth and said winding portion, said two winding teeth and said winding group of said winding portion being connected.

10. The motor as claimed in claim 9, wherein the stator further includes at least two bobbins, each of which is mounted to both ends of the stator core, respectively, the bobbins being shaped to fit the U-shape of the outer circumferential wall and the two winding teeth, the winding groups winding along the bobbins, the two winding teeth, and the winding parts.

11. The electric machine according to claim 10, wherein said bobbin includes at least two connecting teeth via which said winding teeth, said winding portion and a winding group at another said winding tooth are connected.

12. The electric machine of claim 4 further comprising a housing mounted to the exterior of the stator and a cover mounted to one end of the housing to enclose the stator.

13. The motor according to claim 12, wherein the housing includes a first peripheral wall and a second peripheral wall, the first peripheral wall and the second peripheral wall being connected to form a peripheral wall of the housing, wherein the first peripheral wall is shaped to fit the shape of the peripheral wall, the second peripheral wall is opposed to an opening position of the peripheral wall of the stator core, and the second peripheral wall extends straight so as to have a planar outer surface.

14. The motor as claimed in claim 7 or 12, wherein at least two bearings are connected between the housing and the driving shaft, the bearings being respectively provided at both ends of the housing and connected to the driving shaft to support the movement of the driving shaft.