Stator assembly

Abstract

A stator core assembly for an electric motor includes a first stator tooth, a second stator tooth, and a coil. The coil is located near the second stator tooth. The first stator teeth are formed of a first material and the second stator teeth are formed of a second material different from the first material. The first material is a non-grain oriented electrical steel and the second material is a grain oriented electrical steel.

Description

Technical Field

[0001] The present invention relates to a motor stator assembly. Background Art

[0002] There is a general desire to improve electric machines, such as electric motors, in a variety of ways. For example, it may be desirable to improve in terms of size, weight, power density, manufacturing cost, efficiency, reliability, and noise. Summary of the Invention

[0003] According to a first aspect of the present invention, there is provided a stator core assembly for an electric motor, the stator core assembly comprising: a first stator tooth formed of a first material; a second stator tooth formed of a second material different from the first material; and a coil located around the second stator tooth; wherein the first material is non-grain-oriented electrical steel and the second material is grain-oriented electrical steel.

[0004] Compared with an apparatus using non-grain-oriented electrical steel as the stator teeth around which the coil is located, using grain-oriented electrical steel as the second stator teeth around which the coil is located can provide improved motor efficiency of an electric motor including the stator core assembly. The motor efficiency referred to herein may be the ratio of the motor input power to the motor shaft output power of the electric motor.

[0005] Compared with an apparatus using non-grain-oriented electrical steel as the stator teeth around which the coil is located, using grain-oriented electrical steel as the second stator teeth around which the coil is located can make the second stator teeth thinner. For example, since grain-oriented steel can handle a higher magnetic flux density before magnetic saturation, a narrower second tooth can be used relative to an apparatus using non-grain-oriented steel.

[0006] The reduction in the width of the second stator teeth can provide an increased area for positioning the coil relative to a stator core assembly having the same structure but a larger width of the second stator teeth. The increased area can utilize a larger volume of wire, thereby improving motor efficiency.

[0007] The first stator teeth may include unwound stator teeth, for example, stator teeth that do not have a corresponding coil located around the stator teeth. Therefore, the magnetic flux of the first stator teeth may not be as large as that of the second stator teeth, and the first stator teeth may not require the use of oriented steel.

[0008] The first stator tooth may include a first body and a first tooth tip extending outwardly from the first body, the second stator tooth may include a second body and a second tooth tip extending outwardly from the second body, the first body may have a first cross-sectional width, and the second body may have a second cross-sectional width that is substantially the same as the first cross-sectional width. Relative to an arrangement using non-grain-oriented steel for the first stator tooth, using grain-oriented steel for the second stator tooth may reduce the width of the second stator tooth. This may make the width of the second stator tooth similar to the width of the first stator tooth, which may provide an increased slot size. This may enable a greater amount of wire to be utilized, thereby improving motor efficiency.

[0009] The grain-oriented steel of the second stator tooth may be oriented along the length of the stator tooth, such as along the direction from the radially inner end to the radially outer end of the second stator tooth.

[0010] The stator core assembly may include a yoke formed of a first material.

[0011] Since the yoke is formed of a first material and the second stator tooth is formed of a second material, the second stator tooth may be formed separately from the yoke. This may enable a coil to be located around the second stator tooth, for example, wound around the second stator tooth at a location remote from the yoke before the second stator tooth is attached to the yoke. This may provide greater flexibility in the choice of winding method for the coil and may enable the use of a winding method that achieves a relatively high winding fill factor.

[0012] The shape of the yoke may be substantially annular. The yoke may include a substantially continuous ring.

[0013] The yoke and the first stator tooth may be integrally formed, such as integrally formed of a first material. This may reduce the number of components compared to an apparatus in which the yoke and the first stator tooth are formed as separate parts.

[0014] The second stator tooth may be fixed to the yoke by an adhesive. This may provide a relatively simple mechanism for attaching the second stator tooth to the yoke.

[0015] The second stator tooth may include a protrusion, the yoke may include a recess, and the protrusion may be received within the recess. This may facilitate the positioning of the second stator tooth relative to the yoke. The engagement of the protrusion with the wall defining the recess may inhibit the second stator tooth from disengaging from the yoke in the radial direction.

[0016] The first stator tooth may include a channel, and the second stator tooth may include a rib received within the channel. This may facilitate the positioning of the second stator tooth relative to the first stator tooth. The radially inner end of the first stator tooth may include a channel, and the radially inner end of the second stator tooth may include a rib.

[0017] The stator core assembly may include a plurality of first stator teeth formed of a first material, a plurality of second stator teeth formed of a second material, and a plurality of coils, each coil being located around a respective one of the plurality of second stator teeth, and wherein the plurality of first stator teeth and the plurality of second stator teeth may be arranged in an alternating pattern such that each second stator tooth is located midway between two adjacent first stator teeth. In this way, each wound stator tooth may be located between adjacent first stator teeth of the first stator teeth, the coils are located in slots on both sides of the second stator teeth, and each slot is at least partially defined by the first stator teeth and the second stator teeth. Then, using grain-oriented steel as the second stator teeth may allow the width of the second stator teeth to be less than the width required for non-grain-oriented teeth to achieve the same magnetic flux, which may allow an increase in space to position the windings in the manner previously described.

[0018] The stator core assembly may include the same number of first stator teeth and second stator teeth. The stator core assembly may include n second stator teeth, and n may be an integer multiple of 3. The stator core assembly may include a three-phase stator core assembly. The stator core assembly may include exactly six first stator teeth and exactly six second stator teeth.

[0019] According to a second aspect of the present invention, there is provided an electric motor including the stator core assembly according to the first aspect of the present invention.

[0020] The outer diameter of the electric motor may not exceed 75 mm, not exceed 55 mm, not exceed 45 mm, or not exceed 35 mm.

[0021] According to a third aspect of the present invention, there is provided a vacuum cleaner including the electric motor according to the second aspect of the present invention.

[0022] According to a fourth aspect of the present invention, there is provided a cleaning head for a vacuum cleaner, the cleaning head including the electric motor according to the second aspect of the present invention.

[0023] The cleaning head may include a housing and a roller capable of rotating relative to the housing, and the electric motor may be configured to rotate the roller relative to the housing.

[0024] Where appropriate, the optional features of the aspects of the present invention may equally apply to other aspects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of a first embodiment of a stator assembly;

[0026] Figure 2 is included Figure 1 Schematic diagram of an electric motor of a stator assembly;

[0027] Figure 3Schematic diagram of the second embodiment of the stator assembly;

[0028] Figure 4 is a vacuum cleaner including Figure 2 and a schematic diagram of a motor; and

[0029] Figure 5 is Figure 4 a schematic diagram of the cleaning head of the vacuum cleaner. Detailed Description

[0030] Figure 1 The first embodiment of the stator assembly 10 is shown. The stator assembly 10 includes a first stator core member 12 and six winding sub-assemblies 14. It should be understood that more or fewer sub-assemblies may be used depending on the number of teeth required for the stator assembly.

[0031] The first stator core member 12 includes a yoke 16 and six first stator teeth 18. The yoke 16 is annular and is formed by laminations (not shown) of non-grain-oriented electrical steel.

[0032] Each of the first stator teeth 18 has a substantially similar shape and is integrally formed with the yoke 16. Each lamination has a yoke portion and six first stator tooth portions. Thus, the first stator teeth 18 are integrally formed with the yoke 16 and are made of the same non-grain-oriented electrical steel. The first stator teeth 18 extend radially outward from the yoke 16 and are evenly distributed around the outer perimeter of the yoke 16.

[0033] Each of the first stator teeth 18 includes a body 20 and a tooth tip 22. The body 20 has a substantially rectangular cross-sectional shape and extends substantially radially from the yoke 16 and includes undercuts 24 on both sides at the respective interfaces of the body 20 and the yoke 16. The tooth tip 22 extends peripherally outward from the radially outer end of the body 20.

[0034] Each winding sub-assembly 14 includes a second stator core member in the form of a second stator tooth 26 and a coil 28. It can be understood that each winding sub-assembly 14 has substantially the same shape, so for the sake of brevity, only one winding sub-assembly is described here. It should also be understood that each winding sub-assembly 14 may include additional components, such as a bobbin, which are not shown here for clarity.

[0035] The second stator tooth 26 is a component separate from the first stator core member 12 and is formed by stacking laminations (not shown) of grain-oriented electrical steel. The second stator tooth 26 includes a body 30, a guide portion 32, and a tooth tip 34.

[0036] The body 30 is substantially rectangular and has a width substantially the same as the width of the body 20 of the corresponding first stator tooth 18. The body 30 is formed such that the 0° direction of the grain-oriented electrical steel is aligned with the long axis M of the body 30.

[0037] The guiding portion 32 is located at the first end of the main body 30 and includes a first protrusion 38 and a second protrusion 40 that extend radially outward from the main body 30 in the circumferential direction. The shapes and sizes of the first protrusion 38 and the second protrusion 40 are designed to be received within the respective undercuts 24 of adjacent first stator teeth 18 of the first stator core. The tooth tip 34 is located at the second end of the main body 30 and extends radially outward from the second end of the main body 30 in the circumferential direction. The first protrusion 38 and the second protrusion 40 extend further outward from the main body 30 than the tooth tip 34.

[0038] The coil 28 includes a plurality of turns of copper wire having a circular cross-section wound around the main body 30 of the second stator tooth 26. Wires having other cross-sectional shapes are also conceivable.

[0039] To assemble the stator assembly 10 of the first embodiment, the coil 28 is wound around the second stator tooth 26 at a position away from the first stator core member 12. The winding sub-assembly 14 is positioned relative to the first stator core member 12 by axially sliding the winding sub-assembly 14 such that the first protrusion 38 and the second protrusion 40 are respectively received within the respective undercuts 24 of adjacent first stator teeth 18 of the first stator core. An adhesive may be applied to at least one of the first stator core member 12 and the winding sub-assembly 14 before and / or after positioning the winding sub-assembly 14 to fix the winding sub-assembly 14 in place.

[0040] The above operation is repeated for each winding sub-assembly 14 until all six winding sub-assemblies 14 are installed in place. It should be understood that each winding sub-assembly 14 may be wound before being fixed to the first stator core member 12.

[0041] Figure 2 A motor 100 including the stator assembly 10 is shown. The motor 100 includes an outer rotor 102 that includes fourteen permanent magnets 104. The coils 28 are connected in a three-phase manner, the details of which are not relevant and will not be described for the sake of brevity.

[0042] In use, a voltage is applied to the coil 28, thereby generating a magnetic field. This magnetic field interacts with the permanent magnets 104 to cause the outer rotor 102 to rotate relative to the stator assembly 10.

[0043] By segmenting the second stator teeth 26 from the yoke 16, a greater range of winding methods can be achieved compared to an arrangement where the second stator teeth and the yoke are integrally formed. This can enable the use of winding methods that can achieve a greater fill factor within a given slot area. The so-called winding fill factor refers to the ratio of the cross-sectional area of the coil conductive material to the cross-sectional area of the open space within the slot where the coil is located. The increased winding fill factor can result in a reduction in the copper losses of the motor 100 including the stator core assembly 10, thereby resulting in an increase in motor efficiency.

[0044] Since the first stator teeth 18 and the second stator teeth 26 alternate around the circumference of the yoke 16 and only the second stator teeth 26 are wound, a greater slot volume available for copper can be achieved compared to an apparatus where the first stator teeth 18 and the second stator teeth 26 are wound simultaneously. For example, in an apparatus where both the first stator teeth 18 and the second stator teeth 26 are wound, two coils will be located in the same slot, so an air gap is required between the two coils. No air gap is required where only the second stator teeth 26 are wound because there is only one coil within a slot.

[0045] However, winding only the second teeth 26 generally requires each second stator tooth 26 to have a relatively large width to ensure proper magnetic properties. To alleviate this, the second stator teeth 26 are made of grain-oriented steel. Using grain-oriented electrical steel as the second stator teeth 26 can also make the second stator teeth 26 thinner compared to an apparatus using non-grain-oriented electrical steel as the stator teeth around which the coils are located, because grain-oriented steel can handle a higher magnetic flux density before magnetic saturation. The reduction in the width of the second stator teeth 26 provides a greater area for positioning the coils 28, and the greater coil volume results in an increase in the motor efficiency of the motor including the stator assembly 10. In the above manner, the stator assembly 10 can have an optimized slot volume to accommodate the coils therein and accommodate the coils with a relatively high fill factor for a given slot volume.

[0046] Figure 3 A second embodiment of the stator assembly 200 is shown. The second embodiment of the stator assembly 200 includes a first stator core member 202 and six winding sub-assemblies 204.

[0047] The first stator core member 202 includes a yoke 202 and six first stator teeth 208. The yoke 206 is annular and is composed of non-grain-oriented electrical steel laminations (not shown). The yoke 202 includes six receiving channels 210, each receiving channel 210 being located at the center between two adjacent first stator teeth 208. The six receiving channels 210 extend axially along the yoke 206, and their shapes and dimensions are designed to receive the corresponding protrusions 232 of the second stator teeth 216 of the corresponding winding sub-assemblies 204.

[0048] The shapes of each of the first stator teeth 208 are substantially similar and are integrally formed with the yoke 206, where each lamination has a yoke portion and six first stator tooth portions. Thus, the first stator teeth 208 are integrally formed with the yoke 206 and are made of the same non-grain-oriented electrical steel. The first stator teeth 208 extend radially outward from the yoke 206 and are evenly distributed around the outer perimeter of the yoke 206.

[0049] Each of the first stator teeth 208 includes a body 212 and a tip 214. The body 212 has a generally rectangular cross-sectional shape and extends substantially radially from the yoke 206. The tip 214 extends peripherally outward from the radially outer end of the body 20.

[0050] Each winding subassembly 14 includes a second stator core component in the form of a second stator tooth 216 and a coil 218. It should be understood that each winding subassembly 204 has substantially the same form, and thus only one winding subassembly is described here for the sake of brevity. It should also be understood that each winding subassembly 204 may include additional components, such as a bobbin, which are not shown here for clarity.

[0051] The second stator tooth 216 is a component separate from the first stator core component 202 and is formed by stacking laminations (not shown) of grain-oriented electrical steel. The second stator tooth 216 includes a body 220, a guide portion 222, and a tip 224.

[0052] The body 220 is generally rectangular and has a width substantially the same as the width of the body 212 of the corresponding first stator tooth 208. The body 220 is formed such that the 0° direction of the grain-oriented electrical steel is aligned with the long axis M of the body 220.

[0053] The guide portion 222 is located at the first end of the body 220 and includes a first protrusion 228, a second protrusion 230, and a third protrusion 232 that extend outward from the body 220. The first protrusion 228 and the second protrusion 230 extend peripherally outward from the body 220. The third protrusion 232 extends radially from the body 220 and is shaped and sized to be received within a corresponding receiving channel 210 of the yoke 206, thereby inhibiting radial separation of the yoke 206 and the second stator tooth 216.

[0054] The tip 224 is located at the second end of the body 220 and extends peripherally outward from the second end of the body 220.

[0055] The coil 218 includes multiple turns of copper wire with a circular cross-section wound around the body 220 of the second stator tooth 216. Other cross-sectional shapes of the wire are also conceivable.

[0056] The second embodiment of the stator assembly 200 differs from the first embodiment of the stator assembly 10 in the form of attachment between its first stator core member 202 and its winding subassembly 204, wherein the combination of the third protrusion 232 and the corresponding receiving channel 210 serves to inhibit radial separation of the stator core member 202 and the winding subassembly.

[0057] In other respects, the second embodiment of the stator assembly 200 is substantially similar to the first embodiment of the stator assembly 10, particularly in its use of a combination of grain-oriented and non-grain-oriented electrical steel for its stator teeth and the associated technical effects described above. It should be understood that the second embodiment of the stator assembly 200 can be used in a motor similar to the Figure 2 motor 100.

[0058] Figure 4 A vacuum cleaner 300 including the motor 100 is schematically shown. The vacuum cleaner 300 includes a main body 302, a rod 304, and a cleaning head 306.

[0059] Figure 5 The cleaning head 306 is schematically shown and includes a housing 308, a brush bar 310, and the motor 100. The motor 100 is located within the brush bar 310 and is used to drive the brush bar 310 to move within the housing 308 during use. Further details of the cleaning head 306 are not relevant and will not be described here for the sake of brevity.

[0060] Although specific examples and embodiments have been described thus far, it should be understood that these are illustrative only and various modifications can be made without departing from the scope of the invention as defined by the claims.

Claims

1. A stator core assembly for an electric motor, the stator core assembly comprising: A first stator tooth formed of a first material; A second stator tooth formed of a second material different from the first material; And A coil located around the second stator tooth; Wherein the first material is non-grain-oriented electrical steel and the second material is grain-oriented electrical steel.

2. The stator core assembly according to claim 1, wherein, The first stator tooth includes a first body and a first tooth tip extending outward from the first body, the second stator tooth includes a second body and a second tooth tip extending outward from the second body, the first body has a first cross-sectional width, and the second body has a second cross-section substantially the same as the first cross-sectional width.

3. The stator core assembly according to claim 1 or 2, wherein, The stator core assembly includes a yoke formed of the first material.

4. The stator core assembly according to claim 3, wherein, The yoke and the first stator tooth are integrally formed.

5. The stator core assembly according to claim 3 or 4, wherein The second stator tooth is fixed to the yoke by an adhesive.

6. The stator core assembly according to any one of claims 3 to 5, wherein, The second stator tooth includes a protrusion, the yoke includes a recess, and the protrusion is received in the recess.

7. The stator core assembly according to any one of the preceding claims, wherein, The first stator tooth includes a channel, and the second stator tooth includes a rib received in the channel.

8. The stator core assembly according to any one of the preceding claims, wherein, The stator core assembly includes a plurality of first stator teeth formed of the first material, a plurality of second stator teeth formed of the second material, and a plurality of coils, each coil being located around a corresponding one of the plurality of second stator teeth, and wherein the plurality of first stator teeth and the plurality of second stator teeth are arranged in an alternating pattern such that each second stator tooth is located between two adjacent first stator teeth.

9. The stator core assembly according to claim 8, wherein, The stator core assembly includes the same number of first stator teeth and second stator teeth.

10. The stator core assembly according to claim 8 or 9, wherein, The stator core assembly includes n second stator teeth, and n is an integer multiple of 3.

11. The stator core assembly according to any one of claims 8 to 10, wherein, The stator core assembly includes exactly six first stator teeth and exactly six second stator teeth.

12. An electric motor, comprising the stator core assembly according to any one of the preceding claims.

13. A vacuum cleaner, comprising the electric motor according to claim 12.

14. A cleaning head for a vacuum cleaner, the cleaning head comprising the electric motor according to claim 12.

15. The cleaning head according to claim 14, wherein, The cleaning head includes a housing and a roller rotatable relative to the housing, and the electric motor is configured to rotate the roller relative to the housing.

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