Motor

Abstract

The present application provides a motor comprising: a rotor comprising: a rotor top surface; a rotor bottom surface; and at least two rotor bumps formed on the rotor bottom surface; and an impeller coupled to the rotor and positioned above the top surface of the rotor, in which the at least two rotor bumps have different shapes or sizes.

Description

TECHNICAL FIELD

[0001] The present application relates to a motor, in particular, to a motor with rotor lugs. BACKGROUND

[0002] During operation of a motor, uneven weight of the motor rotor is a common problem, which is more likely to cause vibration at high speed. The vibration not only reduces the stability of the motor operation, but also accelerates the wear of the bearing and other components, thereby shortening the service life of the motor. In addition, in order to reduce the vibration, the existing motor design causes fluid turbulence problems.

[0003] Therefore, there is a need for a motor that can improve the operation stability and reduce the vibration. SUMMARY

[0004] The present application provides a motor, comprising: a rotor, comprising: a rotor top surface; a rotor bottom surface; and at least two rotor lugs formed on the rotor bottom surface; and an impeller coupled to the rotor and located above the rotor top surface, wherein the at least two rotor lugs have different shapes or sizes.

[0005] In an embodiment, the at least two rotor lugs are symmetrically arranged about a central axis of the rotor.

[0006] In an embodiment, the at least two rotor lugs have different heights.

[0007] In an embodiment, the rotor further comprises a rotor core, and the at least two rotor lugs have the same material as the rotor core.

[0008] In an embodiment, the rotor further comprises a rotor shell, and the rotor shell has a different material from the rotor core.

[0009] In an embodiment, the impeller comprises an impeller cover plate. The outer edge of the impeller cover plate has at least one recess or protrusion.

[0010] In an embodiment, the impeller cover plate is an impeller top cover or an impeller bottom plate of the impeller.

[0011] The present application provides a motor, comprising: a rotor, comprising: a rotor top surface; a rotor bottom surface; and a rotor lug formed on the rotor bottom surface; and an impeller coupled to the rotor and located above the rotor top surface, wherein a peripheral edge of the impeller is composed of a first outer edge and a second outer edge having different thicknesses.

[0012] In an embodiment, the rotor lug is at least two, and the at least two rotor lugs have different shapes.

[0013] In an embodiment, the at least two rotor lugs have different roughness.

[0014] In an embodiment, the at least two rotor lugs are arranged symmetrically to a center axis of the rotor.

[0015] In an embodiment, the impeller cover disc is an impeller top cover or an impeller bottom disc.

[0016] In an embodiment, the rotor further comprises a rotor core, and the rotor lugs have the same material as the rotor core.

[0017] In an embodiment, the rotor lugs are integrally formed with the rotor core. BRIEF DESCRIPTION OF DRAWINGS

[0018] While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the application, advantages of some embodiments of the application can be more readily understood by reference to the following description, taken in connection with the accompanying drawings, in which:

[0019] Figure 1 is a schematic view of a motor according to some embodiments of the application.

[0020] Figure 2 is a schematic view of a bottom of a rotor according to some embodiments of the application.

[0021] Figure 3 is a schematic view of a bottom of a rotor according to some embodiments of the application, wherein a rotor housing of the rotor is omitted.

[0022] Figure 4 is a schematic view of a motor according to some embodiments of the application.

[0023] Figure 5 is a schematic view of a top of an impeller according to some embodiments of the application.

[0024] Figure 6 is a schematic view of a bottom of an impeller according to some embodiments of the application.

[0025] Figure 7 is a schematic view of a bottom of a motor according to some embodiments of the application, wherein removed parts are indicated in hatching.

[0026] Figure 8A , Figure 8B is a schematic view of a rotor core and rotor magnets according to some embodiments of the application, wherein the positioning structure thereof is emphasized by dashed circles.

[0027] Figure 9A , Figure 9B is a schematic view of a rotor core and rotor housing according to some embodiments of the application, wherein the positioning structure thereof is emphasized by dashed circles.

[0028] Figure 10A 、 Figure 10B is a schematic view of a rotor and an impeller according to some embodiments of the present application, in which positioning structures are emphasized with dotted circles.

[0029] Figure 11 is a schematic view of a motor manufacturing method according to some embodiments of the present application.

[0030] BRIEF DESCRIPTION OF DRAWINGS

[0031] 100: motor,

[0032] 110: rotor,

[0033] 110a: center shaft,

[0034] 111: rotor core,

[0035] 111a: positioning structure,

[0036] 111b: positioning structure,

[0037] 111c: positioning structure,

[0038] 112: rotor magnet,

[0039] 112a: positioning structure,

[0040] 113: rotor housing,

[0041] 113a: positioning structure,

[0042] 113b: positioning structure,

[0043] 114: rotor bump,

[0044] 115: rotor top surface,

[0045] 116: rotor bottom surface,

[0046] 120: impeller,

[0047] 120a: positioning structure,

[0048] 121: impeller top cover,

[0049] 121a: first portion,

[0050] 121b: second portion,

[0051] 122: impeller chassis,

[0052] 122a: first portion,

[0053] 122b: second portion,

[0054] 200: motor manufacturing method,

[0055] 210: step,

[0056] 220: step,

[0057] 230: step,

[0058] 240: step,

[0059] 250: step,

[0060] X: X-axis,

[0061] Y: Y-axis,

[0062] Z: Z-axis. DETAILED DESCRIPTION

[0063] The present application can be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which:

[0064] Certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers can refer to a component by different names. This document does not intend to distinguish between components that differ in name but not in function. In the following description and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to." Also, the term "couple" or "coupled" is intended to mean either an indirect or direct electrical connection. Accordingly, the description and the claims should not be construed as meaning "including, but not limited to," or "comprising, but not limited to," when the term "comprising" or "including" is used.

[0065] Moreover, relative terms can be used herein to describe one component's relationship to another component. For example, a component can be described as being above, below, left of, right of, left of, right of, under, or over another component. Such relative terms can be understood by the one of ordinary skill in the art in view of the overall disclosure herein and should not be construed as limiting the scope of the claims.

[0066] When a component (e.g., a component or a film layer or a region) is referred to as being "on" or "connected to" another component, it can be directly on or connected to the other component, or intervening components can be present. On the other hand, when a component is referred to as being "directly on" or "directly connected to" another component, then there are no intervening components present. In addition, when a component is referred to as being "on" another component, it can be on top of or below the other component in a plan view, and the top or bottom relationship depends on the orientation of the device.

[0067] The terms "about," "substantially," or "approximately" generally mean within 10% of the given value or range, or within 5%, 3%, 2%, 1%, or 0.5% of the given value or range.

[0068] In the present application, when it is stated that a component A overlaps with a component B, it means that at least partial overlap is included.

[0069] It is to be understood that although the terms "first," "second," etc. can be used herein to describe various components, layers, and / or sections, these components, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one component, layer, or section from another. Thus, a first component, layer, and / or section discussed below could be termed a second component, layer, and / or section without departing from the teachings of some embodiments. Also, spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0070] In the present application, the measurement of thickness, length, and width can be measured by optical microscopy, and the thickness can be measured by cross-sectional images in electron microscopy, but not limited thereto. In addition, there can be an error in any two values or directions used for comparison. If the first direction is perpendicular to the second direction, the angle between the first direction and the second direction can be between 80 degrees and 100 degrees; if the first direction is parallel to the second direction, the angle between the first direction and the second direction can be between 0 degrees and 10 degrees.

[0071] It should be noted that the technical solutions provided by different embodiments below can be replaced, combined, or mixed with each other to constitute another embodiment without violating the spirit of the present application.

[0072] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0073] Referring to Figure 1 , Figure 1 is a schematic diagram of a motor 100 according to some embodiments of the present application.

[0074] As shown in Figure 1 , the motor 100 includes a rotor 110 and an impeller 120. The impeller 120 is coupled to the rotor 110, and the impeller 120 can be coaxial with the rotor 110 to improve stability and reduce vibration of the motor 100 when the motor 100 is in operation. The rotor 110 can be driven via electric power (electromagnetic) to drive the impeller 120, and the impeller 120 can drive the fluid around the impeller 120.

[0075] Referring to Figure 2 and Figure 3 . Figure 2 is a bottom view of the rotor 110 according to some embodiments of the present application. Figure 3 is a bottom view of the rotor 110 according to some embodiments of the present application, in which a rotor shell 113 of the rotor 110 is omitted.

[0076] As shown in Figure 2 and Figure 3 , the rotor 110 includes a rotor core 111, a rotor magnet 112, a rotor shell 113, and a rotor bump 114.

[0077] The rotor core 111 has magnetic conductive properties, for example, the rotor core 111 can include metal. For example, the rotor core 111 can include magnetic conductive stainless steel (e.g., SUS 430 or SUS 420J2), or silicon steel, etc. It should be noted that the materials shown herein are merely examples; in fact, the rotor core 111 can also include any appropriate material.

[0078] The rotor magnet 112 is disposed around the rotor core 111; for example, the rotor magnet 112 can surround the rotor core 111. In Figure 3 embodiments, the rotor magnet 112 has a ring shape, such that the rotor magnet 112 completely surrounds the rotor core 111.

[0079] The rotor housing 113 covers the rotor core 111 and the rotor magnets 112. In one embodiment, the rotor housing 113 can comprise a different material from the rotor core 111. For example, the rotor housing 113 can comprise plastic. For example, the rotor housing 113 can be formed on the rotor core 111 and the rotor magnets 112 via plastic overmolding. In this way, the rotor housing 113 does not need to be bonded to the rotor core 111 and the rotor magnets 112 using glue or other bonding components.

[0080] Please refer to Figure 1 and Figure 4 . Figure 4 is a schematic diagram of a motor 100 according to some embodiments of the present application.

[0081] The rotor 110 further comprises a rotor top surface 115 and a rotor bottom surface 116. The rotor top surface 115 and the rotor bottom surface 116 are opposite to each other. The rotor top surface 115 faces the impeller 120, while the rotor bottom surface 116 faces away from the impeller 120.

[0082] The impeller 120 is located above the rotor top surface 115; while the rotor bump 114 is formed on the rotor bottom surface 116, and the rotor bump 114 extends from the rotor bottom surface 116 away from the rotor bottom surface 116.

[0083] According to some embodiments of the present application, the rotor bump 114 is at least two. According to some embodiments of the present application, the at least two rotor bumps 114 are symmetrically arranged with respect to a central axis 110a of the rotor 110. For example, Figure 4 Six rotor bumps 114 are drawn, and the six rotor bumps 114 are symmetrically and uniformly arranged with respect to the central axis 110a of the rotor 110.

[0084] The at least two rotor bumps 114 have the same material as the rotor core 111. Also, according to some embodiments of the present application, the at least two rotor bumps 114 and the rotor core 111 can be integrally formed.

[0085] The at least two rotor bumps 114 have different shapes. For example, the at least two rotor bumps 114 have different sizes or different roughnesses.

[0086] The shape of the rotor bump 114 can be achieved by removing a portion of the rotor bump 114. For example, a portion of the rotor bump 114 can be removed by milling, turning, drilling, grinding, etc. In this way, the shape, height, or roughness of the rotor bump 114 can be changed to change the weight of the rotor bump 114.

[0087] In this way, the stability of the motor 100 during operation can be improved and the vibration of the motor 100 can be reduced. Moreover, the fluid around the impeller 120 can be avoided from being disturbed, and the disturbance of the fluid can be reduced.

[0088] According to some embodiments of the present application, the rotor lugs 114 have different materials from the rotor core 111. Moreover, according to some embodiments of the present application, the rotor lugs 114 can not be integrally formed with the rotor core 111. For example, the rotor lugs 114 having different materials from the rotor core 111 can be attached to the rotor core 111, such that the rotor lugs 114 have different shapes, heights, or roughnesses.

[0089] Referring to Figure 5 and Figure 6 . Figure 5 is a top view of the impeller 120 according to some embodiments of the present application. Figure 6 is a bottom view of the impeller 120 according to some embodiments of the present application.

[0090] The impeller 120 is composed of an impeller cover disc and blades connected to the impeller cover disc. The impeller cover disc includes an impeller top cover 121 and an impeller bottom disc 122. The periphery of the impeller cover disc is the outer edge of the impeller top cover 121 or the outer edge of the impeller bottom disc 122. The outer edge of the impeller top cover 121 can include a first portion 121a and a second portion 121b. The second portion 121b is recessed or protruded relative to the first portion 121a, such that the thickness of the second portion 121b is different from the thickness of the first portion 121a (e.g., the thickness of the second portion 121b is smaller than the thickness of the first portion 121a). That is, the outer edge of the impeller top cover 121 has at least one recessed portion or protruded portion, such that the thickness of the outer edge of the impeller top cover 121 is not uniform.

[0091] The second portion 121b can be formed by removing a portion of the outer edge of the impeller top cover 121. Similarly, the portion of the outer edge of the impeller top cover 121 can be removed by milling, turning, drilling, grinding, or the like. In this way, the shape, height, or roughness of the second portion 121b can be changed to change the weight of the impeller 120.

[0092] In this way, the stability of the motor 100 during operation can be improved and the vibration of the motor 100 can be reduced.

[0093] The outer edge of the impeller base 122 can include a first portion 122a and a second portion 122b. The second portion 122b is recessed relative to the first portion 122a, such that the thickness of the second portion 122b is different from the thickness of the first portion 122a (e.g., the thickness of the second portion 122b is less than the thickness of the first portion 122a). That is, the outer edge of the impeller base 122 has at least one recess or protrusion, such that the thickness of the outer edge of the impeller base 122 is non-uniform.

[0094] The second portion 122b can be formed by removing a portion of the outer edge of the impeller base 122. Similarly, the portion of the outer edge of the impeller base 122 can be removed by milling, turning, drilling, grinding, etc. In this way, the shape, height, or roughness of the second portion 122b can be changed to change the weight of the impeller 120.

[0095] In this way, the stability of the motor 100 during operation can be improved and the vibration of the motor 100 can be reduced. Also, the fluid near the front end of the impeller 120 (around the impeller top cover 121) can be prevented from being disturbed, reducing the disturbance of the fluid.

[0096] Referring to Figure 7 , Figure 7 is a bottom view of a motor 100 according to some embodiments of the present application, in which the portions that have been removed are shown in shading.

[0097] In Figure 7 some embodiments, a portion of two of the rotor lugs 114 (shown in shading) is removed, such that the shape, height, or roughness of the two rotor lugs 114 (shown in shading) is different from the shape, height, or roughness of the other rotor lugs 114. Note that the number of rotor lugs 114 that have a portion removed is merely an example, and any number of rotor lugs 114 can have a portion removed.

[0098] Also, a portion of the second portion 122b of the outer edge of the impeller base 122 is removed, such that the thickness of the outer edge of the impeller base 122 is non-uniform, and the thickness of the second portion 122b is different from the thickness of the first portion 122a (the thickness of the second portion 122b is less than the thickness of the first portion 122a).

[0099] In this way, the stability of the motor 100 during operation can be improved and the vibration of the motor 100 can be reduced. Also, the fluid near the front end of the impeller 120 (around the impeller top cover 121) can be prevented from being disturbed, reducing the disturbance of the fluid.

[0100] According to some embodiments of the present application, a portion of at least one of the rotor lugs 114 is removed, and a portion of the outer edge of the impeller top cover 121 is removed.

[0101] According to some embodiments of the present application, a portion of the outer rim of the impeller top cover 121 is removed, and a portion of the outer rim of the impeller bottom plate 122 is removed.

[0102] According to some embodiments of the present application, a portion of the at least one rotor protrusion 114 is removed, a portion of the outer rim of the impeller top cover 121 is removed, and a portion of the outer rim of the impeller bottom plate 122 is removed.

[0103] According to some embodiments of the present application, only a portion of the outer rim of the impeller top cover 121 is removed.

[0104] According to some embodiments of the present application, only a portion of the outer rim of the impeller bottom plate 122 is removed.

[0105] According to some embodiments of the present application, only a portion of the at least one rotor protrusion 114 is removed.

[0106] In this way, the stability of the motor 100 when in operation can be improved and the vibration of the motor 100 can be reduced.

[0107] Referring to Figure 8A , Figure 8B , Figure 8A , Figure 8B are schematic diagrams of the rotor core 111 and the rotor magnet 112 according to some embodiments of the present application, in which the positioning structures thereof are emphasized by dashed circles.

[0108] As shown in Figure 8A , Figure 8B , the rotor core 111 comprises a positioning structure 111a, and the rotor magnet 112 comprises a positioning structure 112a. The positioning structure 111a of the rotor core 111 can be a protrusion structure, which corresponds to the positioning structure 112a of the rotor magnet 112. The positioning structure 112a of the rotor magnet 112 can be a groove structure, such that the positioning structure 111a of the rotor core 111 can be accommodated therein, and the movement of the positioning structure 111a of the rotor core 111 can be limited to avoid unwanted rotation between the rotor core 111 and the rotor magnet 112.

[0109] Referring to Figure 9A , Figure 9B , Figure 9A , Figure 9B are schematic diagrams of the rotor core 111 and the rotor housing 113 according to some embodiments of the present application, in which the positioning structures thereof are emphasized by dashed circles.

[0110] As shown in Figure 9A , Figure 9BAs shown, the rotor core 111 includes a positioning structure 111b and a positioning structure 111c. The positioning structure 111b is formed on the rotor top surface 115, and the positioning structure 111c is formed on the rotor bottom surface 116. The rotor housing 113 includes a positioning structure 113a and a positioning structure 113b. The positioning structure 113a corresponds to the positioning structure 111b, and the positioning structure 113b corresponds to the positioning structure 111c. In this way, the positioning and combination of the rotor core 111 and the rotor housing 113 can be facilitated.

[0111] Referring to Figure 10A , Figure 10B , Figure 10A , Figure 10B is a schematic diagram of a rotor 110 and an impeller 120 according to some embodiments of the present application, in which the positioning structures thereof are emphasized by dashed circles.

[0112] As shown in Figure 10A , Figure 10B , the impeller 120 includes a positioning structure 120a. The positioning structure 120a corresponds to the positioning structure 111b and the positioning structure 113a. In this way, the positioning and combination of the rotor 110 and the impeller 120 can be facilitated.

[0113] Referring to Figure 11 , Figure 11 is a schematic diagram of a motor manufacturing method 200 according to some embodiments of the present application.

[0114] It should be noted that the components in the motor manufacturing method 200 can correspond to the components of the motor 100, and the similarities thereof will not be elaborated here.

[0115] In step 210, a rotor housing is over-molded on a rotor core of a rotor by plastic injection. The rotor core has magnetic conductive properties, for example, the rotor core can include metal. The rotor housing can include a material different from the rotor core. For example, the rotor housing can include plastic. Wherein the rotor can be the aforementioned rotor 110, the rotor core can be the aforementioned rotor core 111, and the rotor housing can be the aforementioned rotor housing 113.

[0116] In step 220, a first rotor bump is formed on a rotor bottom surface of a rotor. The rotor bottom surface faces away from an impeller. The first rotor bump is formed on the rotor bottom surface, and the first rotor bump extends away from the rotor bottom surface from the rotor bottom surface. Wherein the rotor bottom surface can be the aforementioned rotor bottom surface 116, the first rotor bump can be one of the aforementioned first rotor bumps 114, and the impeller can be the aforementioned impeller 120. The number of the first rotor bump can be one or multiple.

[0117] In step 230, the impeller is coupled to the rotor. The impeller and the rotor can be coaxial (e.g., the central axis 110a).

[0118] In step 240, a second rotor protrusion is formed on a rotor bottom surface of the rotor. The second rotor protrusion is formed on the rotor bottom surface, and the second rotor protrusion extends away from the rotor bottom surface. The first rotor protrusion and the second rotor protrusion can have the same material as the rotor core. The first rotor protrusion and the second rotor protrusion are preferably symmetrically arranged with respect to the central axis of the rotor, and the first rotor protrusion and the second rotor protrusion have different shapes, heights, or roughnesses. The second rotor protrusion can be another one of the aforementioned first rotor protrusions 114. In addition, when the number of the first rotor protrusions is plural, the second rotor protrusion can be formed by modifying at least one of the aforementioned first rotor protrusions.

[0119] Step 250 is optional. In some embodiments of the present application, step 250 is performed, i.e., the motor manufacturing method 200 includes steps 210, 220, 230, 240, and 250. However, in some embodiments of the present application, step 250 can not be performed, i.e., the motor manufacturing method 200 includes steps 210, 220, 230, and 240, but does not include step 250.

[0120] In step 250, a first portion and a second portion are formed on an outer edge of an impeller cover disc of the impeller. The first portion has a first thickness and the second portion has a second thickness, such that the outer edge of the impeller cover disc has at least one concave portion or a protruding portion, and the thickness of the outer edge of the cover disc is not uniform. For example, in an embodiment, an outer edge of an impeller cover disc of an impeller is composed of a first outer edge and a second outer edge having different thicknesses. The impeller cover disc can be at least one of an impeller top cover and an impeller bottom cover, such that the thickness of the outer edge of the impeller cover disc is not uniform. The impeller top cover can be the aforementioned impeller top cover 121, and the impeller bottom cover can be the aforementioned impeller bottom cover 122.

[0121] In summary, the motor and the motor manufacturing method of the embodiments of the present application can effectively improve the stability of the motor during operation and reduce the vibration of the motor. Moreover, the motor and the motor manufacturing method of the embodiments of the present application can avoid disturbing the fluid, thereby reducing the disturbance of the fluid. Furthermore, the motor and the motor manufacturing method of the embodiments of the present application can facilitate the positioning and combination of the components of the motor.

[0122] Although the embodiments and advantages of the present application have been described above, it should be understood that various substitutions, modifications and changes can be made to the application by those skilled in the art without departing from the spirit and scope of the application. It is intended that the application encompass such substitutions, modifications and changes as fall within the scope of the appended claims. In addition, the scope of the application should not be limited to a particular implementation in the specific embodiments described herein. One skilled in the art can readily devise many alternative implementations without departing from the scope of the application as defined by the appended claims. In addition, each of the various embodiments described above can be combined with one another to form additional embodiments without departing from the scope of the application.

Claims

1. A motor characterized by, A motor comprising: a rotor comprising: a rotor top surface; a rotor bottom surface; and at least one rotor protrusion formed on the rotor bottom surface; and an impeller coupled to the rotor and located above the rotor top surface, wherein the at least one rotor protrusion has a different shape or size.

2. The motor of claim 1, wherein: the at least one rotor protrusion is symmetrically disposed about a central axis of the rotor.

3. The motor of claim 1, wherein: the at least one rotor protrusion has a different height.

4. The motor of claim 1, wherein: the rotor further comprises a rotor core, and the at least one rotor protrusion has a same material as the rotor core.

5. The motor of claim 4, wherein: the rotor further comprises a rotor shell, and the rotor shell has a different material than the rotor core.

6. The motor of claim 1, wherein: the impeller comprises an impeller cover disk having at least one recess or protrusion at an outer edge of the impeller cover disk.

7. The motor of claim 6, wherein: the impeller cover disk is an impeller top cover or an impeller bottom cover.

8. A motor characterized by A motor comprising: a rotor comprising: a rotor top surface; a rotor bottom surface; and a rotor protrusion formed on the rotor bottom surface; and an impeller coupled to the rotor and located above the rotor top surface, wherein an impeller peripheral edge of the impeller is comprised of a first outer edge and a second outer edge having different thicknesses.

9. The motor of claim 8, wherein: the rotor protrusion is at least two rotor protrusions, and the at least two rotor protrusions have different shapes.

10. The motor of claim 9, wherein: the at least two rotor protrusions have different roughnesses.

11. The motor of claim 9, wherein: the at least two rotor protrusions are symmetrically disposed about a central axis of the rotor.

12. The motor of claim 7, wherein: the impeller cover disk is an impeller top cover or an impeller bottom cover.

13. The motor of claim 8, wherein: the rotor further comprises a rotor core, and the rotor protrusion has a same material as the rotor core.

14. The motor of claim 13, wherein: the rotor protrusion is integrally formed with the rotor core.

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