Stepper motor

Abstract

The present application relates to the technical field of motors, and specifically relates to a stepper motor. The stepper motor of embodiments of the present application comprises: a rotor assembly; and a stator assembly, wherein the stator assembly comprises a fixed claw pole, a coil, and a housing, the housing comprises a plurality of shell walls sequentially connected in the circumferential direction of the coil, at least one of the plurality of shell walls is configured as a first shell wall, and the outer surface of the first shell wall is planar and is provided with a recessed portion for providing clearance for the coil. In this way, at least one of the plurality of shell walls is configured as a first shell wall, and as the first shell wall is provided with a recessed portion for providing clearance for the coil, a part of the coil is accommodated in the recessed portion, so that the size of the stepper motor in a direction perpendicular to the outer surface of the first shell wall may not comprise the thickness of the first shell wall, thereby facilitating the miniaturization of the stepper motor. In addition, as the outer surface of the first shell wall is planar, this flat surface can easily mate with other components during mounting of the stepper motor, thereby facilitating reduction of the mounting difficulty of the stepper motor.

Description

Stepping motor TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, in particular to a stepping motor. BACKGROUND

[0002] The cross section of the shell of the stepping motor in the prior art is generally circular, and when the stepping motor is assembled into a product such as an electronic device, the size of the assembly space provided for the stepping motor is limited in width and thickness by the diameter of the shell, which is not conducive to product miniaturization.

[0003] Therefore, it is necessary to provide a more miniaturized stepping motor to solve the above technical problems. TECHNICAL PROBLEM

[0004] The purpose of the present application is to provide a stepping motor to solve the technical problem of not being conducive to product miniaturization. TECHNICAL SOLUTION

[0005] The technical solution of the present application is as follows: the embodiment of the present application provides a stepping motor, comprising:

[0006] A rotor assembly, comprising a rotating shaft and a magnetic steel sleeved outside the rotating shaft;

[0007] A stator assembly, sleeved outside the rotor assembly, comprising a fixed claw pole arranged around the outer periphery of the rotor assembly, a coil sleeved outside the fixed claw pole, and a shell sleeved outside the coil;

[0008] The shell comprises a plurality of shell walls connected in sequence along the circumference of the coil, at least one of the plurality of shell walls is configured as a first shell wall, the outer wall of the first shell wall is in a planar shape, the first shell wall is formed with a hollowed-out portion for avoiding the coil, and a part of the coil is accommodated in the hollowed-out portion. ADVANTAGEOUS EFFECTS

[0009] The beneficial effects of the present application are as follows: the stepping motor of the embodiment of the present application comprises a rotor assembly, the rotor assembly comprises a rotating shaft and a magnetic steel sleeved outside the rotating shaft; a stator assembly, the stator assembly is sleeved outside the rotor assembly, the stator assembly comprises a fixed claw pole arranged outside the periphery of the rotor assembly, a coil sleeved outside the fixed claw pole, and an outer shell sleeved outside the coil; the outer shell comprises a plurality of shell walls connected in sequence along the circumference of the coil, at least one of the plurality of shell walls is configured as a first shell wall, the outer wall of the first shell wall is planar, and the first shell wall is formed with a hollow portion for avoiding the coil, and a part of the coil is accommodated in the hollow portion; in the above manner, at least one of the plurality of shell walls is configured as a first shell wall, since the first shell wall is formed with a hollow portion for avoiding the coil, a part of the coil is accommodated in the hollow portion, the size of the stepping motor in the direction perpendicular to the outer wall of the first shell wall can not include the thickness of the first shell wall, the size of the stepping motor in the direction perpendicular to the outer wall of the first shell wall is reduced, which is beneficial to realize the miniaturization of the stepping motor; in addition, since the outer wall of the first shell wall is planar, when the stepping motor is assembled, the planar surface is easy to cooperate with other components, which is beneficial to reduce the assembly difficulty of the stepping motor. BRIEF DESCRIPTION OF DRAWINGS

[0010] Fig. 1 is a perspective view of a stepping motor according to an embodiment of the present application.

[0011] Fig. 2 is a front view of the stepping motor shown in Fig. 1.

[0012] Fig. 3 is a sectional view of the stepping motor shown in Fig. 2 along the A-A direction.

[0013] Fig. 4 is a structural schematic view of a stator assembly in the stepping motor shown in Fig. 1.

[0014] Fig. 5 is a cooperation view of an outer shell and a coil in the stepping motor shown in Fig. 1.

[0015] Fig. 6 is an exploded view of the stepping motor shown in Fig. 1.

[0016] Fig. 7 is a sectional view of the stepping motor shown in Fig. 2 along the B-B line.

[0017] Fig. 8 is a partial structural sectional view of the stepping motor shown in Fig. 6.

[0018] Fig. 9 is a structural schematic view of a fixed claw pole in the stepping motor shown in Fig. 1.

[0019] Fig. 10 is a perspective view of a stepping motor according to an embodiment of the present application.

[0020] Fig. 11 is a perspective view of the stepping motor shown in Fig. 10 from another viewing angle.

[0021] Fig. 12 is a structural schematic view of a stator assembly in the stepping motor shown in Fig. 10.

[0022] Fig. 13 is an exploded view of the housing and coil of the stepper motor of Fig. 10.

[0023] Fig. 14 is an assembled view of the housing and coil of the stepper motor of Fig. 10.

[0024] Fig. 15 is a perspective view of a stepper motor according to an embodiment of the present application.

[0025] Fig. 16 is a schematic view of a stator assembly of the stepper motor of Fig. 15.

[0026] Fig. 17 is an exploded view of the housing and coil of the stepper motor of Fig. 15.

[0027] Fig. 18 is an assembled view of the housing and coil of the stepper motor of Fig. 15.

[0028] Fig. 19 is a perspective view of a stepper motor according to an embodiment of the present application.

[0029] Fig. 20 is a schematic view of a stator assembly of the stepper motor of Fig. 19.

[0030] Fig. 21 is an exploded view of the housing and coil of the stepper motor of Fig. 19.

[0031] Fig. 22 is an assembled view of the housing and coil of the stepper motor of Fig. 19.

[0032] Fig. 23 is a perspective view of a stepper motor according to an embodiment of the present application.

[0033] Fig. 24 is a schematic view of a stator assembly of the stepper motor of Fig. 23.

[0034] Fig. 25 is an exploded view of the stator assembly of the stepper motor of Fig. 23.

[0035] Fig. 26 is an assembled view of a fixed claw pole and support leg assembly of the stepper motor of Fig. 23. Embodiments of the present application

[0036] The present application will be further described with reference to the drawings and embodiments.

[0037] It should be noted that the terms "first", "second", and "third" and the like in the description and in the claims of the present application as well as above-mentioned drawings are used only for distinguishing between similar objects, do not connote any specific order or any specific importance and do not mean any such order or importance. Furthermore, the terms "comprises", "comprising", "includes", "including", "contains", "containing" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, includes, contains or contains a list of steps or elements does not include only those but can optionally include other not-listed steps or elements.

[0038] All directional indications, such as upper, lower, left, right, front, rear, inner, outer, top, bottom, etc., are intended to facilitate the reader's understanding of relative relationships between the various components in a particular orientation (as shown in the figures) and are not intended to limit the present application thereto, and shall change accordingly if the particular orientation changes. When an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or can have a middle element therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or can have a middle element therebetween.

[0039] An embodiment of the present application provides a step motor, please refer to figures 1 to 9, the step motor includes rotor assembly 10 and one or more stator assembly 20.

[0040] Wherein, please refer to figures 3 and 6, the rotor assembly 10 includes the rotating shaft 101 and the magnetic steel 102, the magnetic steel 102 is sleeved on the rotating shaft 101, and the magnetic steel 102 and the rotating shaft 101 can integrally rotate. The magnetic steel 102 can be cylindrical.

[0041] Wherein, figures 1 and 6 to 8 respectively take a plurality of stator assemblies 20 as examples, four stator assemblies 20 are sequentially stacked along the axial direction of the rotor assembly 10, each stator assembly 20 is spaced apart and sleeved on the rotor assembly 10, specifically, the stator assembly 20 is spaced apart and sleeved on the magnetic steel 102, the stator assembly 20 includes the shell 201, the coil 202 and the fixed claw pole 20a, the fixed claw pole 20a is arranged around the outer periphery of the rotor assembly 10, the coil 202 is sleeved and fixed on the fixed claw pole 20a, and the shell 201 is sleeved on the coil 202.

[0042] Wherein, please refer to figures 3, 4 and 5, the shell 201 includes a plurality of shell walls 201a connected in sequence along the circumference of the coil 202, at least one of the plurality of shell walls 201a is configured as a first shell wall 2011, the outer wall of the first shell wall 2011 is planar, and the first shell wall 2011 is formed with a hollow portion 211 for avoiding the coil 202, and a part of the coil 202 is accommodated in the hollow portion 211.

[0043] Wherein, the plurality of shell walls 201a surround to form an accommodation cavity 201b, the inner walls of the plurality of shell walls 201a are sequentially connected to form the inner walls of the accommodation cavity 201b, and the shape of the inner walls of the accommodation cavity 201b matches the shape of the outer wall of the coil 202.

[0044] In the embodiment, by setting at least one of the plurality of shell walls as the first shell wall, since the first shell wall is formed with the hollowed-out portion avoiding the coil, the size of the stepping motor in the direction S1 perpendicular to the outer wall of the first shell wall can not include the thickness of the first shell wall, the size of the stepping motor in the direction S1 perpendicular to the outer wall of the first shell wall is reduced, which is conducive to realizing the miniaturization of the stepping motor; in addition, since the outer wall of the first shell wall is planar, when the stepping motor is assembled, the planar surface is easy to cooperate with other components, which is conducive to reducing the assembly difficulty of the stepping motor.

[0045] As an implementation, referring to FIGS. 12-14, the part of the coil 202 accommodated in the hollowed-out portion 211 is formed with a first plane 2021 parallel to the outer wall of the first shell wall 2011, and the first plane 2021 is located on the outer wall of the coil 202. In the present embodiment, the outer wall of the part of the coil located in the hollowed-out portion is processed into a plane, which further reduces the size in the direction S1 perpendicular to the outer wall of the first shell wall compared with the arc surface before processing, which is conducive to realizing the miniaturization of the stepping motor; or, the saved space can be used to increase the number of turns of the coil or increase the thickness of the claw pole or increase the size of the magnetic steel to further improve the torque performance.

[0046] As an implementation, referring to FIGS. 10-14, two of the plurality of shell walls 201a are configured as the first shell wall 2011, and the two first shell walls 2011 are oppositely arranged. In the present embodiment, two opposite first shell walls are arranged in the same direction, and the size in the direction S1 perpendicular to the outer wall of the first shell wall can not include the thickness of the two first shell walls, which is conducive to further realizing the miniaturization of the stepping motor.

[0047] As an implementation, referring to FIGS. 15-18 and FIGS. 19-22, at least one of the plurality of shell walls 201a is configured as a second shell wall 2012, and the outer wall of the second shell wall 2012 is planar. The second shell wall 2012 is not provided with a hollowed-out portion, and the inner wall of the second shell wall 2012 can be an arc or other shape adapted to the shape of the outer wall of the coil 202. In the present embodiment, the second shell wall with a planar outer wall facilitates the lamination of other electronic devices with the stepping motor, without the need to set other supporting structures or connecting structures, which is conducive to further realizing the miniaturization of the stepping motor.

[0048] In some embodiments, referring to FIG. 15 and FIG. 19, the stepping motor of the present embodiment further comprises a circuit board 30, which can be fixed to any second shell wall 2012. In the present embodiment, the circuit board 30 is more easily attached to the second shell wall with a planar outer wall, and the circuit board can be fixed without the need for setting a pin, which is conducive to further miniaturization of the stepping motor. In the present embodiment, the outgoing line of the coil 202 can be spot-welded to the circuit board using a lead wire, and the outgoing line of the circuit board does not need to be cut off on the second shell wall, thereby improving the structural strength of the stepping motor.

[0049] As an embodiment, referring to FIG. 19 to FIG. 22 and FIG. 23 to FIG. 24, at least one of the plurality of shell walls 201a is configured as a third shell wall 2013, the outer wall of the third shell wall 2013 is an arc surface, and the cross section of the outer wall of the third shell wall 2013 is an arc shape protruding away from the rotation axis 101. In the present embodiment, by setting the third shell wall with an arc-shaped outer wall, it is suitable for application scenarios that require cooperation with an arc surface.

[0050] In some embodiments, referring to FIG. 23 to FIG. 26, the stepping motor of the present embodiment further comprises a circuit board 30, which can be arranged opposite to any third shell wall 2013, and the stator assembly 20 further comprises a support leg assembly 205, which comprises a support skeleton 2051 stacked along the axial direction of the rotor assembly 10 and stacked on the coil 202, and a support leg 2052 extending from the support skeleton 2051 away from the rotation axis 101. The third shell wall 2013 arranged opposite to the circuit board 30 is provided with a relief hole 212, and the support leg 2052 extends to the outside of the shell 201 through the relief hole 212 and is fixedly connected to the circuit board 30. In the present embodiment, by arranging the circuit board opposite to any third shell wall, the outgoing line mode of the circuit board in the background technology can be adapted, thereby enhancing the versatility of the stepping motor of the present embodiment.

[0051] In some embodiments, referring to FIG. 23 to FIG. 25, the first shell wall 2011 is completely hollowed out, and the hollowed-out part 211 extends along the entire first shell wall 2011.

[0052] In some embodiments, referring to FIG. 24 and FIG. 25, the shell 201 comprises four shell walls 201a; two of the four shell walls 201a are configured as first shell walls 2011 (hollowed-out parts 211), and the two first shell walls 2011 (hollowed-out parts 211) are arranged opposite to each other; two of the four shell walls 201a are configured as third shell walls 2013, and the two third shell walls 2013 are arranged opposite to each other.

[0053] As an implementation form, the cross section of the shell 201 is rectangular, and the shell 201 includes four shell walls 201a; the four shell walls 201a can include a first number of first shell walls and a second number of second shell walls, where the first number is n1 and the second number is n2, n1 and n2 are natural numbers respectively, and the sum of n1 and n2 is 4. In this implementation form, by setting the cross section of the shell 201 as a rectangle, the flatness of the stepper motor is facilitated to reduce the size.

[0054] In some implementation forms, as shown in FIGS. 3-5, two of the four shell walls 201a are configured as first shell walls 2011, and the two first shell walls 2011 are oppositely arranged in the width direction of the stepper motor; two of the four shell walls 201a are configured as second shell walls 2012, and the two second shell walls 2012 are oppositely arranged in the length direction of the stepper motor. The height direction of the stepper motor is the axial direction of the rotating shaft 101. In this implementation form, the width of the stepper motor is the diameter of the coil 202, which is conducive to product miniaturization, and the two second shell walls in the length direction are not provided with hollowed-out portions, which is conducive to increasing the structural strength of the product.

[0055] In some implementation forms, as shown in FIGS. 16-18, the four shell walls 201a include one first shell wall 2011 and three second shell walls 2012. Among them, the first shell wall 2011 and one of the second shell walls 2012 are oppositely arranged in the width direction of the stepper motor, and the other two second shell walls 2012 are oppositely arranged in the length direction of the stepper motor. The height direction of the stepper motor is the axial direction of the rotating shaft 101. In this implementation form, the first shell wall is arranged in the width direction, which is conducive to reducing the size in the width direction to miniaturize the product, and the two second shell walls in the length direction and the one second shell wall in the width direction are not provided with hollowed-out portions, which is conducive to increasing the structural strength of the product.

[0056] As an implementation form, the shell 201 includes four shell walls 201a; the four shell walls 201a can include m1 first shell walls, m2 second shell walls, and m3 third shell walls, where m1, m2, and m3 are natural numbers respectively, and the sum of m1, m2, and m3 is 4.

[0057] In some implementation forms, the shell 201 sequentially includes, along the circumference of the coil 202, a first shell wall 2011, a first second shell wall 2012 connected with the first shell wall 2011, a second second shell wall 2012 connected with the first second shell wall 2012, and a third shell wall 2013 connected with the second second shell wall 2012 and the first shell wall 2011.

[0058] In some embodiments, the shell 201 comprises, in sequence along the circumference of the coil 202, a first shell wall 2011, a first second shell wall 2012 connected to the first shell wall 2011, a third shell wall 2013 connected to the first second shell wall 2012, and a second second shell wall 2012 connected to the first shell wall 2011 and the third shell wall 2013, the two second shell walls 2012 being oppositely arranged, and the first shell wall 2011 and the third shell wall 2013 being oppositely arranged.

[0059] In some embodiments, as shown in FIGS. 12-14, the shell 201 comprises, in sequence along the circumference of the coil 202, a first first shell wall 2011, a second shell wall 2012 connected to the first first shell wall 2011, a second first shell wall 2011 connected to the second shell wall 2012, and a third shell wall 2013 connected to the two first shell walls 2011, the two first shell walls 2011 being oppositely arranged, and the second shell wall 2012 and the third shell wall 2013 being oppositely arranged.

[0060] In some embodiments, as shown in FIGS. 20-22, the shell 201 comprises five shell walls 201a; the shell 201 comprises, in sequence along the circumference of the coil 202, a first shell wall 2011, a first second shell wall 2012 connected to the first shell wall 2011, a second second shell wall 2012 connected to the first second shell wall 2012, a third shell wall 2013 connected to the second second shell wall 2012, and a third second shell wall 2012 connected to the third shell wall 2013 and the first shell wall 2011, the first shell wall 2011 and the second second shell wall 2012 being oppositely arranged, and the first second shell wall 2012 and the third second shell wall 2012 being oppositely arranged.

[0061] As an embodiment, as shown in FIGS. 7-9, the fixed claw pole 20a comprises oppositely arranged and cooperated first claw pole part 203 and second claw pole part 204. The first claw pole part 203 comprises a first base 2031 sleeved on the rotating shaft 101 and a first pole claw 2032 extending from the edge of the first base 2031 along the axial direction of the rotating shaft 101 towards the second claw pole part 204, the first pole claws 2032 being spaced along the circumference of the first base 2031; the second claw pole part 204 comprises a second base 2041 sleeved on the rotating shaft 101 and a second pole claw 2042 extending from the edge of the second base 2041 along the axial direction of the rotating shaft 101 towards the first base 2031, the second pole claws 2042 being spaced along the axial direction of the second base 2041; the first pole claws 2032 and the second pole claws 2042 extend alternately, each first pole claw 2032 being located between two adjacent second pole claws 2042, and the first pole claws 2032 and the second pole claws 2042 form a pole claw ring 20b, the coil 202 being sleeved on the pole claw ring 20b.

[0062] In some embodiments, referring to FIG. 9 and FIG. 26, the plurality of first pole claws 2032 are evenly distributed on the inner periphery of the first base 2031, and there is a spacing between two adjacent first pole claws 2032; the plurality of second pole claws 2042 are evenly distributed on the inner periphery of the second base 2041, and there is a spacing between two adjacent second pole claws 2042; when the coil 202 is sleeved on the pole claw ring 20b, the coil 202 is located between the first base 2031 and the second base 2041; when the shell 201 is sleeved on the coil 202, the outer periphery of the first base 2031 and the outer periphery of the second base 2041 respectively abut against the inner wall of the shell 201.

[0063] In some embodiments, referring to FIG. 6, the outer surface of the magnetic steel 102 is formed with a plurality of first magnetic poles 1021 and a plurality of second magnetic poles 1022 staggered along the circumference of the magnetic steel 102, the first magnetic poles 1021 and the second magnetic poles 1022 are magnetically opposite, for example, one is N pole and the other is S pole.

[0064] In some embodiments, referring to FIG. 9, when the first claw pole part 203 and the second claw pole part 204 cooperate with each other, the plurality of first pole claws 2032 of the first claw pole part 203 and the plurality of second pole claws 2042 of the second claw pole part 204 are arranged in a penetrating manner, that is, the second pole claws 2042 are located in the spacing region between two adjacent first pole claws 2032, and the first pole claws 2032 and the second pole claws 2042 are correspondingly arranged with the first magnetic poles 1021 or the second magnetic poles 1022 of the magnetic steel. For the same stator assembly 20, the magnetic properties of the first pole claws 2032 and the second pole claws 2042 are opposite, for example, one is N pole and the other is S pole. Further, the first pole claws 2032 and the second pole claws 2042 are arranged at equal intervals, and the widths of the first pole claws 2032 and the second pole claws 2042 gradually decrease along their respective extension directions.

[0065] In some embodiments, referring to FIG. 3, FIG. 7 and FIG. 8, a cylindrical rubber layer 206 is further arranged between the pole claw ring 20b and the coil 202.

[0066] Please continue to refer to FIG. 3, FIG. 7 to FIG. 8, the stepping motor further comprises a support assembly 40, two support assemblies 40 are respectively arranged at both ends of the rotor assembly 10, referring to FIG. 3, FIG. 4 and FIG. 5, the support assembly 40 comprises an end cover 401 and a bearing 402, the end cover 401 is connected with the rotating shaft 101 through the bearing 402, and the rotating shaft 101 can rotate relative to the end cover 401.

[0067] Further, the top and bottom of the magnetic steel 102 are respectively provided with a gasket 103, the gasket 103 is annular and is sleeved on the rotating shaft 101, and the gasket 103 is located between the magnetic steel 102 and the bearing 402.

[0068] The above merely describes the embodiments of the present application, and it should be pointed out that, for those skilled in the art, improvements can be made without departing from the inventive concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A stepper motor characterized by comprising: The application relates to a step motor. The rotor assembly comprises a rotating shaft and a magnetic steel sleeved outside the rotating shaft. The stator assembly comprises fixed claw poles arranged outside the rotor assembly, coils sleeved outside the fixed claw poles and a shell sleeved outside the coils. The shell comprises a plurality of shell walls connected in sequence along the circumference of the coils, at least one of the shell walls is configured as a first shell wall, the outer wall of the first shell wall is in a planar shape, and the first shell wall is formed with a hollow part for avoiding the coils, and a part of the coils is accommodated in the hollow part.

2. The stepper motor of claim 1, wherein, The part of the coils accommodated in the hollow part is formed with a first plane parallel to the outer wall of the first shell wall.

3. The stepper motor of claim 1, wherein, Two of the shell walls are configured as the first shell walls, and the two first shell walls are oppositely arranged.

4. The stepper motor of claim 1, wherein, At least one of the shell walls is configured as a second shell wall, and the outer wall of the second shell wall is in a planar shape.

5. The stepper motor of claim 4, wherein, The step motor further comprises a circuit board fixed outside the shell, and the circuit board is fixed on any second shell wall.

6. The stepper motor of claim 1, wherein, At least one of the shell walls is configured as a third shell wall, and the outer wall of the third shell wall is in an arc shape.

7. The stepper motor of claim 6, wherein, The step motor further comprises a circuit board fixed outside the shell, and the circuit board is oppositely arranged with any third shell wall.

8. A stepper motor according to claim 4 or 5, wherein The stator assembly further comprises a support leg assembly, the support leg assembly comprises a support framework stacked on the coils along the axial direction of the rotor assembly and support legs extended from the support framework in a direction away from the rotating shaft, and the third shell wall oppositely arranged with the circuit board is provided with an avoiding hole, and the support legs are extended to the outside of the shell through the avoiding hole and are fixedly connected with the circuit board.

9. A stepper motor according to claim 4 or 5, wherein The cross section of the shell is in a rectangular shape, the shell comprises four shell walls, the four shell walls comprise a first number of first shell walls and a second number of second shell walls, the sum of the first number and the second number is 4, and the first number and the second number are natural numbers respectively.

10. The stepper motor according to claim 6 or 7, characterized in that, At least one of the shell walls is configured as a third shell wall, and the outer wall of the third shell wall is in an arc shape.

11. A stepper motor according to any one of claims 1 to 7, wherein The shell comprises four shell walls, two of the four shell walls are configured as the first shell walls, and the two first shell walls are oppositely arranged; two of the four shell walls are configured as the third shell walls, and the two third shell walls are oppositely arranged. The step motor comprises a plurality of stator assemblies and a plurality of shells sleeved outside the plurality of stator assemblies, the plurality of stator assemblies are sequentially and layerwisely arranged along the axial direction of the rotor assembly, and the plurality of shells are sequentially and layerwisely arranged along the axial direction of the rotor assembly. The fixed claw pole comprises a first claw pole part and a second claw pole part oppositely arranged and cooperated with each other, The first claw pole part comprises a first base sleeved outside the rotating shaft and a first pole claw bent and extended from the edge of the first base along the axial direction of the rotating shaft towards the second claw pole part, and the first pole claw is distributed in the circumferential direction of the first base. The second claw pole part comprises a second base sleeved on the rotating shaft and a second pole claw extending from the edge of the second base along the axial direction of the rotating shaft towards the first base, and the second pole claws are distributed at intervals along the axial direction of the second base; The first pole claws and the second pole claws extend alternately, each first pole claw is located between two adjacent second pole claws, and the first pole claws and the second pole claws form a pole claw ring, and the coil is sleeved on the outer periphery of the pole claw ring.

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