Motor with magnetically modified areas

Abstract

The motor includes a stator and a rotor. The stator has a yoke mounted over a ring having a plurality of teeth with gaps therebetween for mounting metal windings. The ring of teeth has an inner circumference that closes and connects the teeth, and an outer circumference with open gaps or slots between the teeth. The metal windings are mounted through the open outer circumference. The area of ​​the closed inner circumference between the teeth is treated so that the magnetic permeability of the area is reduced relative to the rest of the stator. The reduction in magnetic permeability provides a flux barrier between the teeth.

Description

Technical Field

[0001] The present disclosure relates to electric machines, such as electric motors. More particularly, the present disclosure relates to a stator for an electric machine having regions of varying magnetic properties in the regions between teeth separating windings. Background Art

[0002] Electric motors generate force by operating through the interaction between the electric motor's electromagnetic field generated by the rotor and stator. Electric motors can also be used in reverse as generators to convert mechanical energy into electricity.

[0003] Such an electric machine may generally include a rotor, which rotates with a shaft to convey or transmit mechanical power, a stator, which remains stationary and includes windings, an air gap between the rotor and stator, and windings or coils are generally wound around a core so as to form magnetic poles when energized with electric current. Summary of the invention

[0004] According to one embodiment, a stator for an electric motor includes a stator yoke having a first inner surface, and an annular tooth member. The annular tooth member includes a second inner surface, a plurality of teeth extending radially outward therefrom and coupled to the first inner surface, and a material region between the teeth having a reduced magnetic permeability relative to the teeth. The reduction in magnetic permeability in the region provides a flux barrier between the teeth.

[0005] In another embodiment, an electric motor includes a rotor and a stator. The stator has a plurality of teeth arranged around a central axis and separating windings arranged between the teeth. The stator has an inner surface radially spaced from the rotor. The inner surface has a plurality of regions of reduced magnetic permeability. Each of these regions is radially aligned with the windings between the teeth to suppress the magnetic permeability between the teeth.

[0006] In yet another embodiment, a method of manufacturing a stator for an electric motor is provided. The method includes forming a plurality of stator yoke segments, each stator yoke segment having a curved interior region and an interlocking feature. The method also includes reducing the magnetic permeability of a portion of the interior region between teeth in an annular tooth member. The method also includes assembling the stator yoke segments together to form an annular stator yoke by interlocking the individual stator yoke segments, and assembling the stator yoke circumferentially around the annular stator tooth member to form a complete stator core. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a perspective view of a stator according to one embodiment of the present disclosure, wherein the stator includes a stator yoke surrounding an annular tooth member to form the stator.

[0008] Figure 2 yes Figure 1 A perspective view of the stator yoke.

[0009] Figure 3 yes Figure 1 A perspective view of an annular tooth member.

[0010] Figure 4 yes Figure 1 Front view of a sector of the stator.

[0011] Figure 5A is a partial elevation view of one embodiment of the connection between the yoke and the annular tooth member (only two teeth are shown for simplicity).

[0012] Figure 5B is a partial elevation view of another embodiment of the connection between the yoke and the annular tooth member (only two teeth are shown for simplicity).

[0013] Figure 5C is a partial elevation view of yet another embodiment of the connection between the yoke and the annular tooth member (only two teeth are shown for simplicity).

[0014] Figure 6 is a front view of a sector of a stator according to one embodiment, wherein the yoke includes a plurality of segments connected to each other circumferentially around an annular tooth member. DETAILED DESCRIPTION

[0015] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or reduced in order to show the details of a particular component. Therefore, the specific structural and functional details disclosed herein should not be interpreted as restrictive, but only as a representative basis for teaching those skilled in the art to adopt the present disclosure in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for specific applications or implementations.

[0016] As mentioned above, the electric motor generally includes a rotor, a stator, an air gap and windings, among other components. A common stator core design for a radial electric motor includes a circular lamination including a yoke and a plurality of teeth. The spaces present between the teeth are generally referred to as slots and are used to accommodate winding coils. In a randomly wound winding, the coils are pre-wound and inserted into the slots through the openings between the teeth. Due to the circumferential geometry of the laminations and the desire to reduce the gaps between adjacent teeth at the air gap diameter, the openings available for inserting the windings into the slots are very small. This makes it difficult to achieve a high fill factor (e.g., the ratio of copper to total slot area) in the slots.

[0017] The present disclosure provides various embodiments for improving the slot filling factor, including constructing the stator laminations using two separate lamination pieces, namely a first portion having a stator yoke and another portion having all the teeth. As described below, the stator yoke can radially surround the annular tooth member, and the two components are two separate pieces assembled to each other. This allows the coil to be pre-wound and inserted radially from the outer diameter of the stator teeth. After the coil is inserted into the slot between the teeth, a separate lamination ring is used to build the stator yoke assembly.

[0018] refer to Figures 1 to 3 , illustrates a stator for an electric machine. The electric machine, of which the stator may be a part, may be an electric motor, a generator, a motor / generator, etc., wherein rotational energy may be converted into electrical energy and / or vice versa.

[0019] Figure 1 A stator (also referred to as a stator assembly or annular stator assembly) generally 10 for an electric machine is shown. The stator 10 includes a stator yoke 20 (also referred to as a lamination ring or yoke ring) having a plurality of yokes disposed therebetween. Figure 2 The stator yoke 20 is assembled around the annular tooth member 30, as shown in FIG. Figure 3 Shown separately in.

[0020] The annular tooth member 30 includes an inner surface 32 and a plurality of teeth 34 (also referred to as stator teeth) extending radially outward therefrom. Similarly, the stator yoke 20 includes a plurality of surface features 22 (e.g., indentations, pockets, grooves, etc.) that are sized and configured to receive the radial ends of the teeth 32 when assembled. The surface features may be modified to accommodate the shape of the teeth, as described below with reference to FIG. 5A to FIG. 5C described.

[0021] refer to Figure 3 to Figure 4 , the annular tooth member 30 includes an inner surface 32 and a plurality of teeth 34 (also referred to as stator teeth) extending radially outward therefrom. The spaces between the teeth 34 define a gap or space for positioning the winding. The teeth are connected via the inner circumference of the annular tooth member 30 and provide a large slot opening on the outer circumference of the annular tooth member. The large slot opening allows for easy insertion and installation of the winding coil. This results in a simpler winding process, thereby achieving a more efficient winding with shorter end turns and a higher slot filling factor.

[0022] The material (e.g., metal) region connecting the teeth near the inner surface is shown at 36. The material region 36 connecting the teeth constitutes a high permeability path for the slot flux, which can result in a significant increase in the slot leakage flux, thereby resulting in a reduction in the output power of the motor. In order for the motor to have good performance, the slot leakage flux from tooth to tooth without passing through the air gap between the stator and the rotor should be minimized.

[0023] Therefore, according to various embodiments of the present disclosure, the regions 36 are treated, coated or otherwise processed so as to locally reduce or suppress the magnetic permeability through these regions. Various methods of suppressing the magnetic permeability through these regions 36 are explained below. Magnetic separation or suppression through these regions 36 can be provided while maintaining the mechanical connection between the teeth 34. In various embodiments, the regions 36 are treated via one or more of the methods described below to locally suppress the magnetic permeability. The treated regions 36 with reduced magnetic permeability reduce the slot leakage flux by introducing a flux barrier between the teeth at the inner circumference of the stator. In this method, the physical structure of the one-piece annular tooth member 30 remains as a single piece, while its magnetic profile is modified and becomes discontinuous at the region 36.

[0024] Various embodiments for reducing the magnetic permeability in the region 36 between the teeth are contemplated in the present disclosure. These methods provide a flux barrier between the teeth. The magnetic permeability of the region 36 is reduced to be less than the rest of the stator region and ideally equal to or close to the magnetic permeability of air (4πx10 -7 H·m -1 ).

[0025] In one embodiment to reduce the magnetic permeability, an indentation is formed on region 36. A single indentation or an array of indentations may be made to plastically deform region 36. For an array of indentations, the exact shape, location, number, and arrangement of the indentations may vary.

[0026] In another embodiment of reducing the magnetic permeability, the region 36 may be integrally deformed, for example, by using a forming die.

[0027] In another embodiment of reducing the magnetic permeability, the regions 36 may be stamped and a lateral compressive force may be applied to deform each region 36 laterally.

[0028] In another embodiment of reducing the magnetic permeability, peening may be performed on the region 36 by methods such as shot peening, laser peening, cavitation peening, and wet peening.

[0029] The magnetic permeability of region 36 can also be changed by doping and changing the chemical composition of region 36. For example, in one embodiment, the magnetic permeability is reduced or suppressed by inducing a phase transition. When the temperature of the laminate (iron-silicon alloy) rises above a certain point, it undergoes a phase transition to γ-Fe and loses its ferromagnetic properties. This non-ferromagnetic austenite phase can be stabilized at room temperature by adding certain alloying elements (such as manganese or nickel or chromium or molybdenum or a combination of any two or three or all four elements). Local reduction in magnetic permeability can be achieved by first coating a layer of the above one or more elements on the surface of the laminate in the selected area. The laminate is then heat treated at high temperature in a protective environment (e.g., an inert gas such as nitrogen and argon or a vacuum) to diffuse the elements into the laminate. After the laminate is cooled to room temperature, these elements are used to stabilize the non-ferromagnetic austenite structure.

[0030] In another embodiment of reducing the magnetic permeability, the magnetic permeability is suppressed by forming a non-ferromagnetic or low permeability alloy. This can be achieved by first coating the laminate surface in selected areas with a thin layer of at least one element (such as manganese, aluminum, silicon, carbon, sulfur, germanium, nickel and chromium). The laminate is then heat treated at high temperature in a protective environment to diffuse the one or more elements into the laminate. A new non-ferromagnetic or low permeability alloy is formed at the selected area after diffusion.

[0031] Another way to suppress or reduce magnetic permeability is through ion implantation. Using a mask, ions such as oxygen, carbon, and nitrogen can be implanted into regions to produce non-ferromagnetic oxides, carbides, and nitrides. Annealing may be required after ion implantation to restore implant-induced crystal damage and diffuse the doping elements deeper into the stack.

[0032] Once these areas 36 are magnetically modified, the tooth laminations can be bonded or secured together by using dimples or adhesives to form a solid, one-piece tooth core. Similarly, a stator yoke core or yoke ring can be made by adhering or dimples to multiple annular stator yoke laminations. After the winding coils are inserted through the outer circumferential slot openings between the teeth, the stator yoke 20 is installed to direct the magnetic flux. Since a mechanically fixed contact between the annular tooth member 30 and the stator yoke 20 is desired, a locking and alignment mechanism can be used. Various embodiments of this connection are described in detail in detail. FIG. 5A to FIG. 5C Shown in.

[0033] For example, Figure 5A A tooth 34 having a rounded outer end 38 is shown, similar to Figure 3 This locks the stator teeth 34 and the stator yoke 20 with a circular force distribution curve around the circular end 38.

[0034] Figure 5BAnother embodiment is shown in which the teeth 34' are provided with pointed ends 38', each of which terminates in an apex that is generally concentric with each respective end 38'. The respective surface features 22' have an apex that matches the apex of the ends 38'. This provides a single central tip with a tapered end for receiving forces between the teeth and the yoke 20'.

[0035] Figure 5C Another embodiment is shown in which the teeth 34" are provided with pointed ends 38", which terminate at vertices that are eccentric relative to each respective center of each tooth 34". The teeth can be alternated so that the apex of one tooth 34" faces away from the gap between that tooth and an adjacent tooth. In other words, the annular tooth member can have alternating teeth so that the apex of one tooth is offset to the right of center and the apex of the next tooth is offset to the left of center, and so on. This provides a profile with alternating contact vertices to vary the force distribution around the circumference of the annular tooth member.

[0036] refer to Figure 6 In one embodiment, the stator yoke 20 is segmented and assembled together rather than a single integrally formed structure. In this embodiment, the segmented yoke structure 20 may include segments each having an outer stop 42 and an inner stop 44. This allows the stator yoke 20 to be assembled around the teeth piece by piece while ensuring a mechanical connection between the stator yoke and the teeth. Although the outer and inner stops are shown as having a partially circular profile, other designs are contemplated, such as semicircular, equilateral triangles, right triangles, etc. A variety of different shapes and different combinations may be used around the same stator yoke. Additional rings or the housing itself may be required on the outside of the stator yoke to bind or hold all the yoke segments together.

[0037] It should be understood that concepts disclosed with respect to one or more figures may be combined with concepts disclosed in one or more other figures. Figure 6 The connection of the various yoke sections shown and the Figure 5A , Figure 5B and / or Figure 5C The connection between the teeth and the yoke is shown.

[0038] Furthermore, while the embodiments disclosed herein have a stator ring assembled around an annular tooth member, it is contemplated that the annular member could be positioned radially inward from the annular tooth member. In this manner, the teeth would extend radially inward with air gaps at the inner ends of the teeth rather than at the outer ends. The windings would be assembled from the inner region of the tooth member and pressed radially outward, and the annular tooth member would fit around the outer periphery of the stator ring.

[0039] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms included by the claims. The words used in the specification are illustrative rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As mentioned above, the features of the various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or shown. Although various embodiments can be described as providing advantages or being superior to other embodiments or prior art implementations in terms of one or more desired characteristics, it is recognized by those of ordinary skill in the art that one or more features or characteristics can be compromised to achieve the desired overall system properties, which depends on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, applicability, weight, manufacturability, ease of assembly, etc. Therefore, for one or more characteristics, any embodiment is described as less ideal than other embodiments or prior art implementations, which are not outside the scope of the present disclosure and may be desired for specific applications.

[0040] According to the present invention, a stator for an electric machine is provided, having: a stator yoke having a first inner surface; and an annular tooth member, which includes a second inner surface, a plurality of teeth extending radially outward therefrom and connected to the first inner surface, and a material region between the teeth, the material region having a reduced magnetic permeability relative to the teeth to provide a flux barrier between the teeth.

[0041] According to one embodiment, material regions between the teeth magnetically separate the teeth from each other.

[0042] According to one embodiment, the material areas between the teeth provide a mechanical connection between the teeth.

[0043] According to one embodiment, the material regions between the teeth comprise plastically deformed regions to provide a flux barrier.

[0044] According to one embodiment, the annular tooth member is made of a first material and the material regions between the teeth comprise a coating of a second material.

[0045] According to one embodiment, the second material includes at least one of: manganese, aluminum, silicon, carbon, sulfur, germanium, nickel, and chromium.

[0046] According to one embodiment, the annular tooth member includes a plurality of internal wedges, each internal wedge having some of the plurality of teeth, and the internal wedges are coupled together to collectively form the annular member.

[0047] According to one embodiment, the stator yoke comprises a plurality of outer yoke segments, each outer yoke segment is coupled to some of the plurality of teeth, and the outer yoke segments are coupled together to collectively form the stator yoke.

[0048] According to one embodiment, the stator yoke comprises a plurality of outer yoke segments coupled together to collectively form the stator yoke, and the annular member comprises a plurality of inner segments coupled together to collectively form the annular member.

[0049] According to one embodiment, the inner section is part of a single integral annular member.

[0050] According to the present invention, there is provided an electric motor having: a rotor; and a stator having a plurality of teeth arranged around a central axis and having windings separated and arranged between the teeth, the stator having an inner surface radially spaced apart from the rotor, the inner surface having a plurality of regions with reduced magnetic permeability, and each region being radially aligned with the windings between the teeth to suppress the magnetic permeability between the teeth.

[0051] According to one embodiment, each of the regions of reduced permeability provides a mechanical connection between adjacent teeth.

[0052] According to one embodiment, each of the regions of reduced permeability comprises a plastically deformed region to provide a flux barrier between adjacent teeth.

[0053] According to one embodiment, the stator is made of a first material and the region of reduced magnetic permeability is provided with a coating of a corresponding second material.

[0054] According to one embodiment, the second material includes at least one of: manganese, aluminum, silicon, carbon, sulfur, germanium, nickel, and chromium.

[0055] According to the present invention, there is provided a method of manufacturing a stator for an electric motor: forming a plurality of stator segments, each stator segment having a curved interior region and at least two teeth extending radially outward therefrom; for each stator segment, reducing the magnetic permeability of a portion of the interior region between the teeth; assembling the stator segments together to form an annular stator tooth member; and assembling a stator yoke circumferentially around the annular stator tooth member.

[0056] According to one embodiment, the magnetic modification comprises forming one or more indentations on said portion of the inner area between the teeth.

[0057] According to one embodiment, the magnetic modification comprises at least one of: deforming the portion of the inner area between the teeth with a die, punching the portion of the inner area between the teeth with a punch, and shot peening the portion of the inner area between the teeth.

[0058] According to one embodiment, the magnetic modification comprises coating said portion of the inner area between the teeth with a coating.

[0059] According to one embodiment, the magnetic modification comprises implanting ions into said portion of the inner region between the teeth.

Claims

1. A stator for a motor, comprising: a stator yoke having a first inner surface; and An annular tooth member comprising: A second inner surface of a continuous ring shape, a plurality of teeth extending radially outwardly from the second inner surface and coupled to the first inner surface, and Regions of material between the teeth have a reduced magnetic permeability relative to the teeth to provide a flux barrier between the teeth.

2. The stator of claim 1 wherein the material regions between the teeth magnetically separate the teeth from each other.

3. The stator of claim 1 wherein the material regions between the teeth provide a mechanical connection between the teeth.

4. The stator of claim 1 wherein the material regions between the teeth include plastically deformed regions to provide the flux barriers.

5. The stator of claim 1 wherein said annular tooth member is made of a first material and said material regions between said teeth comprise a coating of a second material.

6. The stator of claim 5, wherein the second material comprises at least one of: manganese, aluminum, silicon, carbon, sulfur, germanium, nickel, and chromium.

7. The stator of claim 1, wherein the annular tooth member comprises a plurality of inner wedges, each of the inner wedges having some of the plurality of teeth, and the inner wedges are coupled together to collectively form the annular tooth member.

8. The stator of claim 1, wherein the stator yoke comprises a plurality of outer yoke segments, each of the outer yoke segments being coupled to some of the plurality of teeth, and the outer yoke segments being coupled together to collectively form the stator yoke.

9. The stator of claim 1, wherein the stator yoke comprises a plurality of outer yoke segments coupled together to collectively form the stator yoke, and the annular tooth member comprises a plurality of inner segments coupled together to collectively form the annular tooth member.

10. The stator of claim 9, wherein the inner section is part of a single integral annular tooth member.

11. A motor, comprising: Rotor; and A stator having a plurality of teeth arranged around a central axis and separating windings arranged between the plurality of teeth, the stator having a continuous annular inner surface radially spaced from the rotor, the inner surface having a plurality of regions with reduced magnetic permeability, and each region being radially aligned with the windings between the teeth to suppress the magnetic permeability between the teeth.

12. The electric machine of claim 11, wherein each of the regions of reduced permeability provides a mechanical connection between adjacent teeth.

13. The electric machine of claim 11 wherein each of the regions of reduced permeability comprises a plastically deformed region to provide a flux barrier between adjacent teeth.

14. The electric machine of claim 11, wherein the stator is made of a first material and the region of reduced magnetic permeability is provided with a coating of a corresponding second material.

15. The electric machine of claim 14, wherein the second material comprises at least one of: manganese, aluminum, silicon, carbon, sulfur, germanium, nickel, and chromium.

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