Motor and electric tool

Abstract

The utility model discloses a motor and an electric tool. The motor includes: a rotor including a rotor core; the stator comprises a stator iron core, and the stator iron core comprises an iron core ring and a plurality of stator teeth formed by extending towards the inner side of the iron core ring in the radial direction; the insulating end covers are arranged at the two ends of the stator core, each insulating end cover comprises an annular main body and a plurality of terminal teeth, the plurality of terminal teeth extend towards the inner side of the annular main body along the radial direction, and each terminal tooth is provided with a tooth surface for winding a coil; the tooth surface protrudes in the axial direction to form at least part of an arc-shaped surface. At least part of the tooth surface is arranged to be an inclined surface in the radial direction. Through the arrangement of the arc-shaped surface and the inclined surface, the first layer of coil can be well fixed, so that the follow-up coil is ensured not to slip, and the coil winding can be tightly arranged during winding.

Description

Technical Field

[0001] This application relates to an electric tool, specifically an electric motor and an electric tool. Background Technology

[0002] All power tools include a motor, which drives the working part of the power tool. The motor includes a rotor, a stator, an insulation assembly, and coil windings. The insulation assembly includes two insulating end caps located axially at both ends of the stator. The stator teeth on the stator and the terminal teeth of the two insulating end caps together form winding teeth, on which the coil windings are wound. In related technologies, the coil windings are prone to disordered slippage during winding, resulting in loose windings.

[0003] This section provides background information related to this application, which is not necessarily prior art. Utility Model Content

[0004] One object of this application is to solve or at least alleviate some or all of the aforementioned problems. Therefore, one object of this application is to provide an electric motor and power tools.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] An electric motor, comprising:

[0007] Rotor, including rotor core;

[0008] A stator includes a stator core, the stator core including a core ring and a plurality of stator teeth extending radially toward the inner side of the core ring;

[0009] An insulating end cap is disposed at both ends of the stator core. The insulating end cap includes an annular body and a plurality of terminal teeth. The plurality of terminal teeth extend radially toward the inner side of the annular body and have toothed surfaces for winding coils.

[0010] The tooth surface protrudes axially to form at least a partial arcuate surface;

[0011] At least a portion of the tooth surface is configured as an inclined surface in the radial direction.

[0012] Preferably, the tooth surface is at least partially roughened.

[0013] Preferably, the rough surface includes at least one of the following: a groove whose grooving direction is consistent with the coil winding direction; multiple regular or irregular protrusions; a mesh groove; and multiple raised textures that are substantially consistent with the coil winding direction.

[0014] Preferably, the roughness Ra of the rough surface is less than or equal to 3.2 μm.

[0015] Preferably, the height of the arc-shaped protrusion is greater than or equal to 0.2 mm.

[0016] Preferably, the tilt angle of the tilted surface is greater than or equal to 2° and less than or equal to 45°.

[0017] An electric motor, comprising:

[0018] Rotor, including rotor core;

[0019] A stator includes a stator core, the stator core including a core ring and a plurality of stator teeth extending radially toward the inner side of the core ring;

[0020] An insulating end cap is disposed at both ends of the stator core. The insulating end cap includes an annular body and a plurality of terminal teeth. The plurality of terminal teeth extend radially toward the inner side of the annular body and have toothed surfaces for winding coils.

[0021] At least a portion of the tooth surface is configured as an inclined surface in the radial direction;

[0022] The surface roughness Ra of the tooth is less than or equal to 3.2 μm.

[0023] Preferably, the tooth surface includes at least one of the following: a groove whose grooving direction is consistent with the coil winding direction; multiple regular or irregular protrusions; a mesh groove; and multiple raised patterns that are substantially consistent with the coil winding direction.

[0024] Preferably, the tilt angle of the tilted surface is greater than or equal to 2° and less than or equal to 45°.

[0025] An electric motor, comprising:

[0026] Rotor, including rotor core;

[0027] A stator includes a stator core, the stator core including a core ring and a plurality of stator teeth extending radially toward the inner side of the core ring;

[0028] An insulating end cap is disposed at both ends of the stator core. The insulating end cap includes an annular body and a plurality of terminal teeth. The plurality of terminal teeth extend radially toward the inner side of the annular body and have toothed surfaces for winding coils.

[0029] The surface roughness Ra of the tooth is greater than 3.2 μm.

[0030] An electric tool includes a housing, a working part, and a motor as described in any of the above embodiments, wherein the motor is disposed in the housing and is capable of driving the working part to work.

[0031] The advantage of this application is that it can better fix the first layer of coil, thereby ensuring that the subsequent coils do not slip, and thus the coil windings can be tightly arranged during winding. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the motor provided in this embodiment of the present invention when no press-fitting parts are provided and the filler is set independently;

[0033] Figure 2 yes Figure 1 A sectional view;

[0034] Figure 3 yes Figure 1 A schematic diagram of the decomposed structure;

[0035] Figure 4 This is a schematic diagram of the structure of the motor provided in this embodiment of the present invention when the motor does not have a press-fit component and the filler is integrally formed;

[0036] Figure 5 yes Figure 4 A sectional view;

[0037] Figure 6 yes Figure 4 A schematic diagram of the decomposed structure;

[0038] Figure 7 This is a schematic diagram of the structure of the motor with press-fitting parts and independently set filler provided in the embodiment of this utility model;

[0039] Figure 8 yes Figure 7 A sectional view;

[0040] Figure 9 yes Figure 7 A schematic diagram of the decomposed structure;

[0041] Figure 10 This is a schematic diagram of the structure of the motor with press-fitting parts and filler integrally provided in the embodiment of this utility model;

[0042] Figure 11 yes Figure 10 A sectional view;

[0043] Figure 12 yes Figure 10 A schematic diagram of the decomposed structure;

[0044] Figure 13 This is a schematic diagram of the structure of the motor provided in this embodiment of the present invention when a press-fit component is provided but no filler is provided;

[0045] Figure 14 yes Figure 13 A sectional view;

[0046] Figure 15 yes Figure 13 A schematic diagram of the decomposed structure;

[0047] Figure 16 This is a cross-sectional view of the insulating component involved in the embodiment of this utility model along the first direction;

[0048] Figure 17 This is a cross-sectional view of the insulating component involved in the embodiments of this utility model along the second direction;

[0049] Figure 18 This is a top view of the insulating component involved in the embodiments of this utility model when the tooth surface is in the first structural form;

[0050] Figure 19 This is a top view of the insulating component involved in the embodiments of this utility model when the tooth surface is in the second structural form;

[0051] Figure 20 This is a top view of the insulating component involved in the embodiments of this utility model when the tooth surface has a third structural form;

[0052] Figure 21 This is a schematic diagram of the structure of each lobe of the segmented motor in an embodiment of this utility model;

[0053] Figure 22 This is a top view of the structure of the segmented motor in an embodiment of this utility model.

[0054] In the picture:

[0055] 10. Stator core; 11. Core ring; 12. Stator tooth; 121. Main body; 122. Extension; 20. Coil winding; 30. Insulation assembly; 31. Insulation end cap; 311. Ring body; 312. Terminal tooth; 3121. Tooth surface; 3122. Tooth end; 32. Fitting part; 40. Filler; 50. Press-fit part. Detailed Implementation

[0056] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0057] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0058] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0059] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0060] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​not using relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0061] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0062] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0063] This utility model provides a power tool, specifically a handheld tool, and more specifically, a polishing machine. It is understood that the power tool can also be a handheld power tool, such as a drill, pruning machine, or sander. Alternatively, the power tool can be a benchtop tool, such as a table saw or miter saw. Alternatively, the power tool can be a push-type power tool, such as a push lawnmower or push snowplow. Alternatively, the power tool can be an outdoor wheeled tool or an outdoor electric vehicle. Alternatively, the power tool can be a ride-on power tool, such as a ride-on lawnmower, ride-on vehicle, or all-terrain vehicle. Alternatively, the power tool can be a robotic tool, such as a lawnmower robot or a snowplow robot. In some embodiments, the power tool can be an electric drill, a light bulb, or an electric vehicle. In some embodiments, the power tool can also be a garden tool, such as a pruning machine, a hair dryer, a lawnmower, or a chainsaw. Alternatively, the power tool can also be a decorating tool, such as a screwdriver, a nail gun, a circular saw, or a sander. In some embodiments, power tools can also be vegetation care tools, such as lawn mowers, lawn trimmers, pruning machines, chainsaws, etc. Alternatively, power tools can be cleaning tools, such as hair dryers, snowplows, washing machines, etc. Alternatively, power tools can be drilling tools, such as drills, screwdrivers, wrenches, hammer drills, etc. Alternatively, power tools can be sawing tools, such as reciprocating saws, jigsaws, circular saws, etc. Alternatively, power tools can be bench tools, such as table saws, miter saws, metal cutters, bakelite milling machines, etc. Alternatively, power tools can be sanding tools, such as angle grinders, sanders, etc. Alternatively, power tools can be other tools, such as fans, etc.

[0064] The power tool specifically includes a housing, a motor, and a working part. The motor is housed within the housing and drives the working part to operate. In this embodiment, the power tool is a polishing machine, and the working part can specifically be a polishing disc, which is driven to rotate by the motor.

[0065] like Figures 1 to 15As shown in the figure, the motor includes a rotor, a stator, an insulating component 30, and a coil winding 20. Among them, the rotor includes a rotor core and a rotor shaft. The rotor shaft can rotate around the first axis, and the rotor core and the rotor shaft rotate synchronously. The stator includes a stator core 10. The stator core 10 is arranged around the first axis, and the rotor core is arranged inside the stator core 10. The stator core 10 includes a core ring 11 and a plurality of stator teeth 12. The core ring 11 is a ring around the first axis. The stator teeth 12 extend radially inward from the inner wall of the core ring 11 perpendicular to the first axis, and the plurality of stator teeth 12 are arranged in sequence in the circumferential direction around the first axis. The insulating component 30 includes two insulating end caps 31 and a sleeved portion 32 disposed between the two insulating end caps 31. The two insulating end caps 31 are respectively used to cover both ends of the stator teeth 12 along the first axis direction, and the sleeved portion 32 covers the middle part of the stator teeth 12. The insulating end cap 31 includes an annular main body 311 and a plurality of terminal teeth 312. The annular main body 311 is a ring around the first axis. The plurality of terminal teeth 312 extend radially inward to the inside of the annular main body 311 perpendicular to the first axis and correspond to the plurality of stator teeth 12 one by one. Each stator tooth 12 and the corresponding two terminal teeth 312 are continuous along the first axis and abut against each other, jointly forming a winding tooth. The coil winding 20 includes a plurality of coils, and the plurality of coils are respectively wound around the plurality of winding teeth.

[0066] More specifically, the stator tooth 12 includes a main body portion 121 and an extension portion 122 whose pair of tips extend away from the main body portion 121 in the circumferential direction and towards the adjacent stator tooth 12. The terminal tooth 312 includes a tooth surface 3121 and tooth ends 3122 arranged in the circumferential direction. The coil is wound around the main body portion 121 and the tooth surface 3121, and the extension portion 122 and the tooth ends 3122 are used to limit the coil.

[0067] For power tools, during the working process, the motor may generate relatively large noise when rotating at high speed. One of the sources of relatively harsh whistling is caused by the resonance of the motor. Especially for tools such as polishers, users need to operate in an environment with relatively low noise as much as possible. Therefore, we hope to eliminate the resonance of the motor as much as possible. Among them, the principle of the motor resonance is: when the motor rotates at high speed, the rotor shaft will have a rotational frequency f that varies within a preset range. This preset range can be from a to b, that is to say, a < f < b. And the stator core 10 in the motor has a first natural frequency f1. When the rotational frequency f of the rotor shaft during rotation is the same as the first natural frequency f1, the motor will resonate, thereby generating relatively large noise, which will further affect the operation of the user. In fact, when an integer multiple of the rotational frequency f of the rotor shaft during rotation is the same as the first natural frequency f1, the motor will also resonate. That is to say, when nf = f1 (n is a positive integer), resonance will also occur.

[0068] To reduce motor noise, a continuous wall is formed on the inner side of the stator core 10. The natural frequency of the stator core 10 with a continuous inner wall is at least 10% higher than the natural frequency of the stator core 10 without a continuous inner wall. After the continuous inner wall is formed, the stator core 10 has a second natural frequency f2, which is at least 10% higher than the first natural frequency f1 of the stator core 10 before the continuous inner wall is formed. That is, by forming a continuous inner wall, the natural frequency of the stator core 10 is changed, thereby avoiding frequencies where the motor may resonate, and thus improving motor noise.

[0069] In some embodiments, the continuous wall surface formed inside the stator core 10 can be a smooth wall surface or a non-smooth wall surface.

[0070] The motor also includes a filler 40, which is disposed at least between adjacent stator teeth 12, and the filler 40 can form a continuous wall with two adjacent stator teeth 12.

[0071] Reference Figures 1 to 6 In some embodiments, the gap between the extensions 122 of two adjacent stator teeth 12 is at least partially filled with filler 40. For example, filler 40 may be filled between all adjacent extensions 122, or it may be selectively filled between adjacent extensions 122. The length of filler 40 may fill the gap between adjacent extensions 122 completely, or it may fill a portion of the gap between adjacent extensions 122. The thickness of filler 40 may be flush with the extension 122, or it may be concave outward or convex inward along a radial direction perpendicular to the first axis. The surface of filler 40 may be smooth or rough.

[0072] Reference Figures 1 to 3 In some embodiments, the filler 40 filling the space between two adjacent extensions 122 is provided independently. For example, the filler 40 is a strip, and the strips are not connected to each other. (Refer to...) Figures 4 to 6 In some embodiments, the filler 40 filling the space between two adjacent extensions 122 is integrally formed. For example, the filler 40 is a strip, and the strips are connected integrally by a connector.

[0073] In some embodiments, the gap between the tips 3122 of two adjacent terminal teeth 312 is at least partially filled with filler 40. For example, filler 40 may be filled between all adjacent tips 3122, or it may be selectively filled between adjacent tips 3122. The length of filler 40 may be to fill the gap between adjacent tips 3122 completely, or it may fill only a portion of the gap between adjacent tips 3122. The thickness of filler 40 may be flush with the tip 3122, or it may be recessed outward or protruded inward along a radial direction perpendicular to the first axis. The surface of filler 40 may be smooth or rough.

[0074] In some embodiments, the filler 40 is a non-metallic material, such as fiber-reinforced nylon, BMC (Bulk Molding Compound), PC (Polycarbonate), ABS (Acrylonitrile Butadiene Styrene), AB glue (two-component curing adhesive), etc. In some embodiments, the filler 40 is a metallic material, such as aluminum alloy, steel, etc.

[0075] In some embodiments, molten material (thermoplastic material such as nylon, thermosetting material such as BMC) can be injected into the gap to be filled using a mold to form filler 40. In some embodiments, filler 40 can be formed by pressing a strip into the gap to be filled. In some embodiments, filler 40 can be formed by injecting adhesive into the gap to be filled.

[0076] In some embodiments, the motor further includes a filling member disposed adjacent to the inner side of the stator core 10. In some embodiments, the filling member is a cylindrical member. In some embodiments, the filling member is a sheet member, and the width of the sheet member is greater than the gap between two adjacent extensions 122.

[0077] Reference Figures 7 to 15 In some embodiments, the motor further includes a press-fit component 50, which is fixed to the outer periphery of the stator core 10 by an interference fit to apply a fastening force to the stator core 10. Specifically, the press-fit component 50 is an annular component with a first axis as its central axis, which is fitted onto the outer periphery of the core ring 11 of the stator core 10. After being assembled to the outer periphery of the core ring 11 of the stator core 10, the press-fit component 50 forms an interference fit with the core ring 11, making it difficult for the user to remove the press-fit component 50 and the stator core 10 without external tools. The press-fit component 50 can also change the natural frequency of the stator core 10, allowing the motor to avoid frequencies that may resonate, thus improving motor noise.

[0078] It is understandable that the natural frequency of the stator core 10 can be changed simply by setting the filler 40, as shown in the reference. Figures 1 to 6 Alternatively, both filler 40 and press-fitting component 50 can be set simultaneously to change the natural frequency of stator core 10, as shown in the reference. Figures 7 to 12 Alternatively, the natural frequency of the stator core 10 can be changed by simply setting the press-fit component 50, as shown in the reference. Figures 13 to 15 All of the above methods can improve motor noise.

[0079] In addition, for the motor, it is desirable for the coil winding 20 to be tightly arranged during winding. On the one hand, this allows for more space when the number of coil turns remains unchanged, thereby improving the motor's heat dissipation capacity; on the other hand, it allows for the maximum number of coil turns when the number of coil turns is not limited, thereby increasing the slot fill factor.

[0080] like Figure 16 and Figure 17 As shown, in some embodiments, to ensure that the coil windings 20 are tightly arranged during winding, the tooth surface 3121 of the terminal teeth 312 protrudes axially to form at least a partially arcuate surface, and at least a portion of the tooth surface 3121 of the terminal teeth 312 is radially inclined. This arrangement effectively secures the first layer of coils, preventing slippage of subsequent coils and allowing the coil windings 20 to be tightly arranged during winding.

[0081] In some embodiments, the height of the arc-shaped protrusion is greater than or equal to 0.2 mm.

[0082] In some embodiments, the tilt angle of the inclined surface is greater than or equal to 2° and less than or equal to 45°.

[0083] Furthermore, the tooth surface 3121 of the terminal tooth 312 is at least partially roughened to further improve the fixing effect of the first layer of coil. In some embodiments, the roughened surface includes a groove whose slotting direction is consistent with the coil winding direction, such as... Figure 18 As shown. In some embodiments, the roughened surface includes a plurality of regular or irregular protrusions, such as... Figure 19 As shown. In some embodiments, the roughened surface includes mesh-like grooves, such as... Figure 20 As shown. In some embodiments, the rough surface includes a plurality of raised textures that are substantially aligned with the coil winding direction.

[0084] In some embodiments, the roughness Ra of the rough surface is less than or equal to 3.2 μm.

[0085] like Figure 16As shown, or in some embodiments, in order to ensure that the coil windings 20 can be tightly arranged during winding, at least a portion of the tooth surface 3121 of the terminal teeth 312 is set as an inclined surface in the radial direction, and the roughness Ra of the tooth surface 3121 is less than or equal to 3.2 μm. With the above settings, the first layer of coils can also be better fixed, thereby ensuring that the subsequent coils do not slip, and thus enabling the coil windings 20 to be tightly arranged during winding.

[0086] In some embodiments, the tilt angle of the inclined surface is greater than or equal to 2° and less than or equal to 45°.

[0087] In some embodiments, the roughened surface includes a groove whose slotting direction is consistent with the coil winding direction, such as... Figure 18 As shown. In some embodiments, the roughened surface includes a plurality of regular or irregular protrusions, such as... Figure 19 As shown. In some embodiments, the roughened surface includes mesh-like grooves, such as... Figure 20 As shown. In some embodiments, the rough surface includes a plurality of raised textures that are substantially aligned with the coil winding direction.

[0088] Alternatively, in some embodiments, to ensure that the coil windings 20 can be tightly arranged during winding, the roughness Ra of the tooth surface 3121 of the terminal teeth 312 is greater than 3.2 μm. With the above setting, even if the tooth surface 3121 is not tilted, the first layer of coil can be fixed well, thereby ensuring that the subsequent coils do not slip, and thus enabling the coil windings 20 to be tightly arranged during winding.

[0089] In some embodiments, the motor may further include a segmented motor. For example... Figure 21 and Figure 22 As shown, the stator core 10 of the motor is divided into multiple segments, and the coil windings 20 are wound around each segment. After the segments are spliced ​​together, they form a ring-shaped core. To reduce the noise of the segmented motor or to ensure the firmness of the spliced ​​segments, filler 40 can be applied to the gaps between the spliced ​​stator teeth through various processes such as injection molding, press fitting, or potting. The filling material and filling method of filler 40 can be referred to the description of the above embodiment, and will not be repeated here.

[0090] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. An electric machine, comprising: a rotor comprising a rotor core; a stator comprising a stator core (10) comprising a core ring (11) and a plurality of stator teeth (12) extending radially inwardly of the core ring (11); insulating end caps (31) arranged at both ends of the stator core (10), the insulating end caps (31) comprising an annular body (311) and a plurality of terminal teeth (312) extending radially inwardly of the annular body (311), the terminal teeth (312) having tooth surfaces (3121) for winding coils; characterized in that the tooth surfaces (3121) are formed at least partially as axially convex arc surfaces; at least a portion of the tooth surfaces (3121) are arranged as radially inclined surfaces.

2. The electric machine of claim 1, wherein, at least a portion of the tooth surfaces (3121) are arranged as rough surfaces.

3. The electric machine of claim 2, wherein, the rough surfaces comprise at least one of grooves having a groove direction coinciding with the winding direction of the coils, a plurality of regular or irregular protrusions, a meshed groove, and a plurality of protruding lines coinciding substantially with the winding direction of the coils.

4. The electric machine of claim 2, wherein, the roughness Ra of the rough surfaces is less than or equal to 3.2 pm.

5. The electric machine of claim 1, wherein, the height of the convex arc surfaces is greater than or equal to 0.2 mm.

6. The electric machine of claim 1, wherein, the inclination angle of the inclined surfaces is greater than or equal to 2° and less than or equal to 45°.

7. An electric machine, comprising: a rotor comprising a rotor core; a stator comprising a stator core (10) comprising a core ring (11) and a plurality of stator teeth (12) extending radially inwardly of the core ring (11); insulating end caps (31) arranged at both ends of the stator core (10), the insulating end caps (31) comprising an annular body (311) and a plurality of terminal teeth (312) extending radially inwardly of the annular body (311), the terminal teeth (312) having tooth surfaces (3121) for winding coils; characterized in that at least a portion of the tooth surfaces (3121) are arranged as radially inclined surfaces. the roughness Ra of the tooth surfaces (3121) is less than or equal to 3.2 pm.

8. The electric machine of claim 7, wherein, the tooth surfaces (3121) comprise at least one of grooves having a groove direction coinciding with the winding direction of the coils, a plurality of regular or irregular protrusions, a meshed groove, and a plurality of protruding lines coinciding substantially with the winding direction of the coils.

9. The electric machine of claim 7, wherein, the inclination angle of the inclined surfaces is greater than or equal to 2° and less than or equal to 45°.

10. An electric machine, comprising: a rotor comprising a rotor core; a stator comprising a stator core (10) comprising a core ring (11) and a plurality of stator teeth (12) extending radially inwardly of the core ring (11); insulating end caps (31) arranged at both ends of the stator core (10), the insulating end caps (31) comprising an annular body (311) and a plurality of terminal teeth (312) extending radially inwardly of the annular body (311), the terminal teeth (312) having tooth surfaces (3121) for winding coils; characterized in that The roughness Ra of the tooth surface (3121) is greater than 3.2 μm.

11. An electric power tool characterized by comprising: The motor is arranged in the shell, and the motor can drive the working part to work.

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