阅读说明：本技术 定子冲片以及具有该定子冲片的定子、电机和电器装备 (Stator punching sheet, stator with same, motor and electric equipment ) 是由 葛梦 吴迪 龚黎明 诸自强 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种定子冲片以及具有它的定子、电机和电器装备。定子冲片包括：定子轭部；和N个定子齿部,每个定子齿部包括齿身、第一和第二极靴,定子轭部的中心轴线和齿身的中心线在第一平面上的投影分别为第一点和第一直线,第一极靴和第二极靴在第一平面上的投影分别具有第一和第二周沿以及第三和第四周沿,第二周沿位于第一周沿与定子轭部之间,第四周沿位于第三周沿与定子轭部之间,第一周沿的端点与第一点的连线与第一直线的夹角为α,第三周沿的端点与第一点的连线与第一直线的夹角为β,0°<α<180°/Ν,180°/Ν<β<360°/Ν。该定子冲片具有齿槽效应小等优点,有效降低电机的齿槽转矩、转矩脉动和振动噪音。(The invention discloses a stator punching sheet, a stator with the same, a motor and electric equipment. Stator punching includes: a stator yoke; and each stator tooth comprises a tooth body, a first pole shoe and a second pole shoe, the projection of the central axis of the stator yoke part and the central line of the tooth body on the first plane is respectively a first point and a first straight line, the projection of the first pole shoe and the second pole shoe on the first plane is respectively provided with a first peripheral edge, a second peripheral edge, a third peripheral edge and a fourth peripheral edge, the second peripheral edge is positioned between the first peripheral edge and the stator yoke part, the fourth peripheral edge is positioned between the third peripheral edge and the stator yoke part, the connecting line of the end point of the first peripheral edge and the first point forms an included angle alpha, the connecting line of the end point of the third peripheral edge and the first point forms an included angle beta with the first straight line, and the included angle alpha is 0 degrees and less than 180 degrees and N degrees, and the 180 degrees and N degrees and the beta is less than 360 degrees and N degrees. The stator punching sheet has the advantages of small cogging effect and the like, and effectively reduces the cogging torque, the torque pulsation and the vibration noise of the motor.)

1. A stator punching sheet is characterized by comprising:

a stator yoke; and

n stator teeth, N stator teeth are arranged at intervals along the circumferential direction of the stator yoke, a punching sheet slot is formed between two adjacent stator teeth, each stator tooth comprises a tooth body, a first pole shoe and a second pole shoe, the tooth body is connected with the stator yoke, the projection of the central axis of the stator yoke on a first plane is a first point, the projection of the central axis of the tooth body on the first plane is a first straight line, the projection of the first pole shoe on the first plane is provided with a first circumferential edge and a second circumferential edge which extend along the circumferential direction of the stator yoke, the projection of the second pole shoe on the first plane is provided with a third circumferential edge and a fourth circumferential edge which extend along the circumferential direction of the stator yoke, the second circumferential edge is located between the first circumferential edge and the stator yoke in the radial direction of the stator yoke, and the fourth circumferential edge is located between the third circumferential edge and the stator yoke in the radial direction of the stator yoke A line connecting an end point of the first circumferential edge far from the tooth body and the first point is a first line, a line connecting an end point of the third circumferential edge far from the tooth body and the first point is a second line, wherein an included angle between the first line and the first straight line is alpha, an included angle between the second line and the first straight line is beta, 0 ° < alpha <180 °/n, 180 °/n < beta <360 °/n, and the first plane is perpendicular to the central axis of the stator.

2. The stator lamination as recited in claim 1, comprising a plurality of the lamination slots, wherein the notches of the plurality of the lamination slots are equal to each other in size in a circumferential direction of the stator yoke portion.

3. The stator lamination as recited in claim 1 or 2, characterized in that 0 ° <360 °/Ν - α - β ≦ 5 °.

4. The stator lamination as recited in claim 1 or 2, wherein a ratio of β to α is greater than or equal to 1.3 and less than or equal to 4.

5. A stator, characterized by comprising a plurality of stator laminations, each stator lamination being according to any one of claims 1-4.

6. The stator as claimed in claim 5, wherein the stator comprises a plurality of stator slots, and a dimension of each of the stator slots in a circumferential direction of the stator is constant in an axial direction of the stator.

7. The stator according to claim 6,

the lengths of the first pole shoes of the stator laminations are increased along the axial direction of the stator, the lengths of the second pole shoes of the stator laminations in the circumferential direction of the stator are decreased along the axial direction of the stator,

or the lengths of the first pole shoes of the stator laminations are reduced along the axial direction of the stator, and the lengths of the second pole shoes of the stator laminations are increased along the axial direction of the stator.

8. The stator as claimed in claim 5, wherein the stator comprises a plurality of stator slots, each of which increases or decreases in size in a circumferential direction of the stator in an axial direction of the stator.

9. The stator according to claim 8, wherein each of the stator slots is gradually increased or decreased in size in a circumferential direction of the stator in an axial direction of the stator.

10. The stator according to claim 8 or 9,

the lengths of the first pole shoes of the stator punching sheets are reduced along the axial direction of the stator, the lengths of the second pole shoes of the stator punching sheets are reduced along the axial direction of the stator,

or the lengths of the first pole shoes of the stator laminations are increased along the axial direction of the stator, and the lengths of the second pole shoes of the stator laminations are increased along the axial direction of the stator.

11. An electric machine, comprising:

a rotor; and

a stator according to any one of claims 5 to 10.

12. Electrical equipment, characterized in that it comprises an electrical machine according to claim 11.

Technical Field

The invention relates to the field of motors, in particular to a stator punching sheet, and further relates to a stator, a motor and electric equipment with the stator punching sheet.

Background

The related art single-phase brushless dc motor has only 1-phase winding, so there is a dead point position and the starting performance of the motor is poor. In order to solve this problem, the magnetic pole center of the stator and the magnetic pole center of the rotor are offset by using a tapered air gap or an asymmetric tooth structure, thereby avoiding a starting dead point. However, this causes an increase in cogging of the motor, an increase in cogging torque and torque ripple, and a large vibration noise problem.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention provides a stator punching sheet, a stator with the stator punching sheet, a motor and electrical equipment.

The stator punching sheet comprises a stator yoke part; and N stator teeth, the N stator teeth being arranged at intervals along a circumferential direction of the stator yoke, a punching slot being formed between two adjacent stator teeth, each stator tooth including a tooth body, a first pole shoe and a second pole shoe, the tooth body being connected to the stator yoke, a projection of a central axis of the stator yoke on a first plane being a first point, a projection of a center line of the tooth body on the first plane being a first straight line, a projection of the first pole shoe on the first plane having a first circumferential edge and a second circumferential edge extending in a circumferential direction of the stator yoke, a projection of the second pole shoe on the first plane having a third circumferential edge and a fourth circumferential edge extending in the circumferential direction of the stator yoke, the second circumferential edge being located between the first circumferential edge and the stator yoke in a radial direction of the stator yoke, the fourth circumferential edge is located between the third circumferential edge and the stator yoke in a radial direction of the stator yoke, a line connecting an end point of the first circumferential edge far from the tooth body and the first point is a first line, a line connecting an end point of the third circumferential edge far from the tooth body and the first point is a second line, wherein an included angle between the first line and the first straight line is α, an included angle between the second line and the first straight line is β, 0 ° < α <180 °/Ν, 180 °/Ν < β <360 °/Ν, and the first plane is perpendicular to the central axis of the stator yoke

The stator punching sheet has the advantage of small cogging, and the starting performance of the motor can be improved, the cogging torque and the torque ripple of the motor can be effectively reduced, and the vibration noise of the motor can be effectively reduced.

Optionally, the stator punching sheet comprises a plurality of punching grooves, and the sizes of the notches of the plurality of punching grooves in the circumferential direction of the stator yoke portion are equal to each other.

Alternatively, 0 ° <360 °/Ν - α - β ≦ 5 °.

Alternatively, the ratio of β to α is 1.3 or more and 4 or less.

The stator comprises a plurality of stator laminations, and each stator lamination is the stator lamination according to the embodiment of the invention.

The stator provided by the embodiment of the invention has the advantage of small cogging, and the stator provided by the embodiment of the invention can be used for improving the starting performance of the motor, effectively reducing the cogging torque and the torque ripple of the motor and further effectively reducing the vibration noise of the motor.

Optionally, the stator comprises a plurality of stator slots, and the size of each stator slot in the circumferential direction of the stator is constant along the axial direction of the stator.

Optionally, the lengths of the first pole shoes of the plurality of stator laminations are increased along the axial direction of the stator, and the lengths of the second pole shoes of the plurality of stator laminations in the circumferential direction of the stator are decreased along the axial direction of the stator, or the lengths of the first pole shoes of the plurality of stator laminations are decreased along the axial direction of the stator, and the lengths of the second pole shoes of the plurality of stator laminations are increased along the axial direction of the stator.

Optionally, the stator comprises a plurality of stator slots, each of which increases or decreases in size in a circumferential direction of the stator in an axial direction of the stator.

Optionally, the size of each stator slot in the circumferential direction of the stator gradually increases or gradually decreases in the axial direction of the stator.

Optionally, the lengths of the first pole shoes of the stator laminations decrease along the axial direction of the stator, and the lengths of the second pole shoes of the stator laminations decrease along the axial direction of the stator, or the lengths of the first pole shoes of the stator laminations increase along the axial direction of the stator, and the lengths of the second pole shoes of the stator laminations increase along the axial direction of the stator.

The motor according to an embodiment of the present invention includes: a rotor; and a stator according to an embodiment of the present invention.

The motor provided by the embodiment of the invention has the advantages of good starting performance, small cogging torque, small torque pulsation and small vibration noise.

An electrical apparatus according to an embodiment of the invention comprises a motor according to an embodiment of the invention.

The electric equipment provided by the embodiment of the invention has the advantage of low vibration noise.

Drawings

Fig. 1 is a schematic structural diagram of a stator lamination according to an embodiment of the invention;

FIG. 2 is a schematic partial structural view of a stator according to an embodiment of the present invention;

FIG. 3 is a schematic partial structural view of a stator according to an embodiment of the present invention;

FIG. 4 is a schematic partial structural view of a stator according to an embodiment of the present invention;

fig. 5 is a partial structural view of a stator according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

A stator punching sheet 10 according to an embodiment of the present invention is described below with reference to the drawings. As shown in fig. 1 to 5, a stator punching sheet 10 according to an embodiment of the present invention includes a stator yoke 110 and N stator teeth 120, where the N stator teeth 120 are spaced apart from each other in a circumferential direction of the stator yoke 110, and a punching sheet slot 130 is formed between two adjacent stator teeth 120. Each stator tooth 120 includes a tooth body 121, a first pole piece 122, and a second pole piece 123, and the tooth body 121 is connected to the stator yoke 110. A projection of the center axis of stator yoke 110 on the first plane is a first point O, and a projection of the center line of tooth body 121 on the first plane is a first straight line L1.

The projection of the first pole shoe 122 on this first plane has a first circumferential edge 1221 and a second circumferential edge 1222 running in the circumferential direction of the stator yoke 110, the second circumferential edge 1222 being located between the first circumferential edge 1221 and the stator yoke 110 in the radial direction of the stator yoke 110. The projection of the second pole piece 123 on the first plane has a third circumferential edge 1231 and a fourth circumferential edge 1232 extending in the circumferential direction of the stator yoke 110, the fourth circumferential edge 1232 being located between the third circumferential edge 1231 and the stator yoke 110 in the radial direction of the stator yoke 110.

A connection line between the end point P1 of the first peripheral edge 1221 away from the tooth body 121 and the first point O is a first connection line L2, and a connection line between the end point P2 of the third peripheral edge 1231 away from the tooth body 121 and the first point O is a second connection line L3. In other words, an end point P1 of the first circumferential edge 1221 is distant from the tooth body 121 in the circumferential direction of the stator yoke 110, and an end point P2 of the third circumferential edge 1231 is distant from the tooth body 121 in the circumferential direction of the stator yoke 110.

An included angle between the first line L2 and the first straight line L1 is α, an included angle between the second line L3 and the first straight line L1 is β, 0 ° < α <180 °/Ν, 180 °/Ν < β <360 °/Ν, and the first plane is perpendicular to the central axis of the stator yoke 110.

The stator lamination 10 according to the embodiment of the present invention can make the first and second pole pieces 122 and 123 of the stator teeth 120 asymmetrical with respect to the tooth bodies 121 thereof by making 0 ° < α <180 °/Ν and 180 °/Ν < β <360 °/Ν. Therefore, the stator magnetic field and the rotor magnetic field have larger offset degree, so that the motor with the stator punching sheet 10 has larger starting torque and better starting performance.

The asymmetric tooth design of the related art is achieved by cutting down the length of one of the first and second pole pieces. That is, one of the first and second pole pieces has a length that is less than the length of the pole piece in a symmetrical tooth design (i.e., the pole piece without the length cut), and the other of the first and second pole pieces has a length that is equal to the length of the pole piece in a symmetrical tooth design. Therefore, compared with the stator punching sheet with the symmetrical tooth design, the notch of the punching sheet groove of the stator punching sheet with the asymmetrical tooth design in the related art is larger, so that the cogging effect is increased, the cogging torque and the torque ripple of the motor are increased, and the vibration noise of the motor is increased.

The stator punching 10 according to the embodiment of the present invention can make the length of the first pole piece 122 smaller than that of the stator punching having the symmetrical tooth design and the length of the second pole piece 123 larger than that of the stator punching having the symmetrical tooth design by making 0 ° < α <180 °/Ν, 180 °/Ν < β <360 °/Ν.

Therefore, the width of the notch 131 of the punching sheet groove 130 of the stator punching sheet 10 is less than or equal to the width of the notch of the stator groove of the stator punching sheet with the symmetrical tooth design, and the width of the notch 131 of the punching sheet groove 130 of the stator punching sheet 10 is less than the width of the notch of the stator groove of the stator punching sheet with the asymmetrical tooth design. Therefore, the cogging effect can be effectively reduced, so that the cogging torque and the torque ripple of the motor can be effectively reduced, and the vibration noise of the motor can be reduced. Wherein, the width of the notch 131 means: the size of the slot 131 in the circumferential direction of the stator yoke 110.

Therefore, the stator punching sheet 10 according to the embodiment of the present invention has the advantages of small cogging, and the like, and the stator punching sheet 10 according to the embodiment of the present invention can not only improve the starting performance of the motor, but also effectively reduce the cogging torque and the torque ripple of the motor, and further effectively reduce the vibration noise and the equivalent air gap of the motor.

The invention also provides a stator 1. The stator 1 according to the embodiment of the present invention includes a plurality of stator laminations 10 according to the above-described embodiment of the present invention. Therefore, the stator 1 according to the embodiment of the present invention has the advantages of small cogging, and the like, and by using the stator 1 according to the embodiment of the present invention, not only can the starting performance of the motor be improved, but also the cogging torque and the torque ripple of the motor can be effectively reduced, and further, the vibration noise of the motor can be effectively reduced.

The stator laminations 10 of the stator 1 can be assembled in a known manner to form a stator core. For example, a plurality of stator laminations 10 can be laminated together. Since this is irrelevant to the point of the present application, it is not described in detail.

As shown in fig. 1 to 5, the stator 1 includes a plurality of stator laminations 10, each stator lamination 10 includes a stator yoke portion 110 and a plurality of stator teeth 120, and each stator tooth 120 includes a tooth body 121, a first pole shoe 122 and a second pole shoe 123.

The first pole piece 122 and the second pole piece 123 can be connected to the tooth body 121 in a known manner. For example, the end of the first pole piece 122 is connected to the end of the tooth body 121, the end of the second pole piece 123 is connected to the end of the tooth body 121, the first pole piece 122 extends in a clockwise direction from the tooth body 121, and the second pole piece 123 extends in a counterclockwise direction from the tooth body 121.

The tooth body 121 is connected to the stator yoke 110. A plurality of stator teeth 120 are provided at intervals in the circumferential direction of stator yoke 110, and a plurality of tooth bodies 121 are provided at intervals in the circumferential direction of stator yoke 110. Wherein the circumferential direction of the stator yoke 110 coincides with the circumferential direction of the stator 1. Alternatively, tooth body 121 is removably coupled to stator yoke 110. Therefore, the stator yoke part 110 and the stator tooth part 120 can be respectively machined, so that winding is facilitated, and the slot filling rate of the motor is improved.

The punched piece groove 130 is formed between two adjacent stator teeth 120. Specifically, the punched slot 130 may be defined by the stator yoke 110, the tooth body 121 and the first pole piece 122 of one stator tooth 120, and the tooth body 121 and the second pole piece 123 of another stator tooth 120.

A projection of the center axis of stator yoke 110 on the first plane is a first point O, and a projection of the center line of tooth body 121 on the first plane is a first straight line L1. The first plane is perpendicular to the central axis of stator yoke 110.

The projection of the first pole shoe 122 on this first plane has a first circumferential edge 1221 and a second circumferential edge 1222 running in the circumferential direction of the stator yoke 110, the second circumferential edge 1222 being located between the first circumferential edge 1221 and the stator yoke 110 in the radial direction of the stator yoke 110. The projection of the second pole piece 123 on the first plane has a third circumferential edge 1231 and a fourth circumferential edge 1232 extending in the circumferential direction of the stator yoke 110, the fourth circumferential edge 1232 being located between the third circumferential edge 1231 and the stator yoke 110 in the radial direction of the stator yoke 110.

A connection line between the end point P1 of the first peripheral edge 1221 away from the tooth body 121 and the first point O is a first connection line L2, and a connection line between the end point P2 of the third peripheral edge 1231 away from the tooth body 121 and the first point O is a second connection line L3. In other words, an end point P1 of the first circumferential edge 1221 is distant from the tooth body 121 in the circumferential direction of the stator yoke 110, and an end point P2 of the third circumferential edge 1231 is distant from the tooth body 121 in the circumferential direction of the stator yoke 110. The included angle between the first line L2 and the first straight line L1 is α, the included angle between the second line L3 and the first straight line L1 is β, 0 ° < α <180 °/Ν, and 180 °/Ν < β <360 °/Ν.

Optionally, the length of the first pole piece 122 is smaller than a preset value, and the length of the second pole piece 123 is larger than the preset value. The length of the first pole piece 122 refers to: the dimension of the first pole shoe 122 in the circumferential direction of the stator yoke 110; the length of the second pole piece 123 refers to: the dimension of the second pole shoe 123 in the circumferential direction of the stator yoke 110.

Alternatively, the ratio of β to α is 1.3 or more and 4 or less. Therefore, the stator punching sheet 10 and the stator 1 have smaller cogging effect, the starting performance of the motor can be further improved, and the cogging torque, the torque pulsation and the vibration noise of the motor can be further reduced.

As shown in fig. 1, the stator punching sheet 10 includes a plurality of punching grooves 130, and the sizes of the notch 131 of the plurality of punching grooves 130 in the circumferential direction of the stator yoke portion 110 are equal to each other. That is, the widths of the plurality of punched grooves 130 are equal to each other.

Alternatively, 0 ° <360 °/Ν - α - β ≦ 5 °. That is, the central angle γ corresponding to the punching sheet groove 130 is greater than 0 ° and not greater than 5 °, that is, the central angle γ is 360 °/Ν - α - β. Therefore, the stator punching sheet 10 and the stator 1 have smaller cogging effect, the starting performance of the motor can be further improved, and the cogging torque, the torque pulsation and the vibration noise of the motor can be further reduced.

After the plurality of stator laminations 10 are assembled together, the lamination slots 130 of the plurality of stator laminations 10 form the stator slots 20 of the stator 1. Accordingly, the stator 1 comprises a plurality of stator slots 20.

As shown in fig. 2 and 3, the size of each stator slot 20 in the circumferential direction of the stator 1 is kept constant in the axial direction of the stator 1, that is, the width of each stator slot 20 is kept constant in the axial direction of the stator 1.

As shown in fig. 2 and 3, the length of the first pole piece 122 of the plurality of stator laminations 10 increases along the axial direction of the stator 1, and the length of the second pole piece 123 of the plurality of stator laminations 10 decreases along the axial direction of the stator 1, so that the width of each stator slot 20 is kept constant along the axial direction of the stator 1. Since the circumferential direction of the stator yoke 110 coincides with the circumferential direction of the stator 1, the length of the first pole shoe 122 is also the dimension of the first pole shoe 122 in the circumferential direction of the stator 1, and the length of the second pole shoe 123 is also the dimension of the second pole shoe 123 in the circumferential direction of the stator 1.

The length of the first pole shoe 122 is thereby varied in the axial direction of the stator 1, so that the degree of offset of the stator magnetic field and the rotor magnetic field can be further increased in order to further increase the starting torque of the electrical machine.

In addition, the length of the first pole shoe 122 of the plurality of stator laminations 10 decreases along the axial direction of the stator 1, and the length of the second pole shoe 123 of the plurality of stator laminations 10 increases along the axial direction of the stator 1. The length of the first pole shoe 122 is thereby varied in the axial direction of the stator 1, so that the degree of offset of the stator magnetic field and the rotor magnetic field can be further increased in order to further increase the starting torque of the electrical machine.

As shown in fig. 4 and 5, the size of each stator slot 20 in the circumferential direction of the stator 1 increases or decreases in the axial direction of the stator 1, that is, the width of each stator slot 20 increases or decreases in the axial direction of the stator 1. Thereby the width of the stator slots 20 varies in the axial direction of the stator 1, i.e. the stator 1 has stator slots 20 of unequal width, whereby the cogging torque and the torque ripple of the motor can be further reduced, so that the vibration noise of the motor can be further reduced.

Alternatively, the size of each stator slot 20 in the circumferential direction of the stator 1 gradually increases or gradually decreases in the axial direction of the stator 1, that is, the width of each stator slot 20 gradually increases or gradually decreases in the axial direction of the stator 1. Thereby the width of the stator slots 20 is gradually changed along the axial direction of the stator 1, i.e. the stator 1 has stator slots 20 with unequal widths, so that the cogging torque and the torque ripple of the motor can be further reduced to further reduce the vibration noise of the motor.

As shown in fig. 4 and 5, the lengths of the first pole shoes 122 of the plurality of stator laminations 10 decrease (gradually decrease) along the axial direction of the stator 1, and the lengths of the second pole shoes 123 of the plurality of stator laminations 10 decrease (gradually decrease) along the axial direction of the stator 1. Thereby, the cogging torque and the torque ripple of the motor can be further reduced to further reduce the vibration noise of the motor.

In addition, the lengths of the first pole shoes 122 of the plurality of stator laminations 10 increase (gradually increase) along the axial direction of the stator 1, and the lengths of the second pole shoes 123 of the plurality of stator laminations 10 increase (gradually increase) along the axial direction of the stator 1. Thereby, the cogging torque and the torque ripple of the motor can be further reduced to further reduce the vibration noise of the motor.

The invention also provides a motor. The motor according to the embodiment of the present invention includes a rotor and a stator 1 according to the above-described embodiment of the present invention. Therefore, the motor provided by the embodiment of the invention has the advantages of good starting performance, small cogging torque, small torque ripple, small vibration noise and the like.

The rotor may be known and the rotor and stator 1 may be fitted in a known manner. Since these are not related to the point of the invention of the present application, they are not described in detail. The motor according to the embodiment of the invention can be an outer rotor motor and can also be an inner rotor motor.

Optionally, the rotor has a plurality of permanent magnets arranged at intervals in a circumferential direction of the rotor. The circumferential direction of the rotor coincides with the circumferential direction of the stator 1. The thickness of the plurality of permanent magnets is gradually reduced or gradually increased along the rotation direction of the rotor. Therefore, the center line of the stator magnetic field and the center line of the rotor magnetic field can be deviated, and the starting of the motor is facilitated.

Optionally, the air gap between the pole shoes of the stator 1 and the rotor is gradually decreasing or gradually increasing in the direction of rotation of the rotor. Therefore, the center line of the stator magnetic field and the center line of the rotor magnetic field can be deviated, and the starting of the motor is facilitated.

In addition, the stator punching sheet 10 and the stator 1 can reduce the equivalent air gap of the motor, so that the adverse effect caused by the gradual change air gap can be counteracted, and the output torque of the motor is prevented from being reduced.

The invention also provides electrical equipment. An electrical apparatus according to an embodiment of the invention comprises a motor according to the above-described embodiment of the invention. Therefore, the electric equipment provided by the embodiment of the invention has the advantages of low vibration noise and the like.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.