Rotor core and axial flux motor including the same

Abstract

The invention relates to a rotor core and an axial flux motor including the same. A rotor core according to an embodiment includes a plurality of block units formed in an arc shape, in which the plurality of block units are stacked in a radial direction, and the plurality of block units are coupled in a circumferential direction to form an annular shape.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0125128, filed on September 12, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a rotor core and an axial flux motor including the rotor core, and more particularly to a rotor core that is easy to manufacture and has excellent performance in reducing iron losses due to eddy currents, and an axial flux motor including the rotor core. Background Technology

[0004] An axial flux motor (AFM) is an electric motor that guides magnetic flux axially. It is known to have higher torque and efficiency compared to a radial flux motor (RFM), which guides magnetic flux radially. AFMs are also easier to modularize and can be reduced in size compared to RFMs, making them suitable for a wider range of applications.

[0005] Typically, soft magnetic composite (SMC) cores are used for rotors of axial flux motors; however, there is no advantage in reducing iron losses if the rotor is manufactured using an SMC core.

[0006] When rotors are manufactured using electrical steel sheets with excellent properties that reduce iron loss, rotor manufacturing presents a challenge because each electrical steel sheet must be manufactured in a different size if they are stacked in the direction that reduces eddy currents.

[0007] The matters described in the background section are intended to enhance the understanding of the background of the invention and may include matters unknown to those skilled in the art. Summary of the Invention

[0008] The present invention seeks to provide a rotor core that is easy to manufacture and at the same time reduces iron loss, an axial flux motor including the rotor core, and an electric water pump including the axial flux motor.

[0009] The rotor core according to the embodiment includes a plurality of block units formed in an arc shape, wherein the plurality of block units are stacked in the radial direction and the plurality of block units are connected along the circumferential direction to form an annular shape.

[0010] In some implementations, the diameter and circumferential length of multiple block elements can increase from the radially inward side to the radially outward side.

[0011] An axial flux motor according to an embodiment includes a stator assembly comprising a stator core and coils wound around the stator core. The axial flux motor also includes a rotor assembly configured to rotate via electromagnetic interaction with the stator assembly. The rotor assembly includes permanent magnets disposed on two axial sides of the stator assembly, and each rotor core disposed on the outer axial side of the permanent magnets. The rotor core includes block segments stacked in the radial direction and formed into an arcuate shape, and the block segments are connected in the circumferential direction to form a ring shape.

[0012] In some implementations, the diameter and circumferential length of multiple block units of the rotor core can increase from the radially inner side to the radially outer side.

[0013] In some implementations, the air gaps formed between the block segments can be filled with glass fiber reinforced polymer material.

[0014] In some embodiments, the permanent magnet may include a first pole magnet and a second pole magnet with a polarity different from that of the first pole magnet. The first pole magnet and the second pole magnet may be arranged at equal intervals along the circumferential direction.

[0015] In some implementations, a first pole magnet may be arranged between the block section and the stator core, and a second pole magnet may be arranged between the boundary of the block section and the stator core.

[0016] In some implementations, the saturation of the back yoke can be minimized at the boundaries of the block segment.

[0017] In some embodiments, the stator core may include stator teeth arranged or spaced apart at predetermined intervals along a circumferential direction. The stator core may also include stator slots, each formed between the stator teeth, in which coils are wound. The stator core may also include statorshoes extending radially inward from the stator teeth toward the stator slots.

[0018] In some embodiments, the stator assembly may include a stator body, an upper stator coil wound on the upper surface of the stator body, and a lower stator coil wound on the lower surface of the stator body.

[0019] In some implementations, the axial flux motor may further include a block support member formed in the lower part of the block section of the rotor core.

[0020] In some implementations, permanent magnets can be arranged between block support members.

[0021] According to the disclosed implementation, the rotor core can be easily manufactured from electrical steel sheet by manufacturing the rotor core from block segments of multiple block units stacked in the radial direction.

[0022] Furthermore, since the boundaries between the block sections used for the rotor back yoke are not located in the path of the magnetic flux, the impact on motor performance can be minimized while making the manufacturing process easy.

[0023] Furthermore, the effects that can be obtained or are expected by the embodiments of the present invention are disclosed, directly or implicitly, in the detailed description of the embodiments of the present invention. In other words, the various effects that can be expected by the embodiments of the present invention are disclosed in the detailed description below. Attached Figure Description

[0024] Since the accompanying drawings are provided for reference in describing embodiments of the invention, the technical spirit of the invention should not be construed as being limited to the drawings.

[0025] Figure 1 This is a perspective view showing the configuration of an axial flux motor according to an embodiment of the present invention.

[0026] Figure 2 This is an exploded perspective view showing the configuration of an axial flux motor according to an embodiment of the present invention.

[0027] Figure 3 This is a perspective view showing the configuration of the rotor core of an axial flux motor according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram illustrating the flux path of an axial flux motor according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram illustrating the analysis results of the flux saturation of an axial flux motor according to an embodiment of the present invention.

[0030] Figure 6 This is a perspective view showing the configuration of an axial flux motor according to another embodiment of the present invention.

[0031] Figure 7 and Figure 8 This is an exploded perspective view showing the configuration of an axial flux motor according to an embodiment of the present invention.

[0032] Figure 9 This is a perspective view showing the configuration of an axial flux motor according to yet another embodiment of the present invention.

[0033] It should be understood that the above figures are not necessarily drawn to scale, but rather show a fairly simplified representation of the various features illustrating the basic principles of the invention. Specific design features of the invention (including, for example, specific dimensions, orientations, positions, and shapes) will be determined in part by the specific target application and environment of use.

[0034] Description of reference numerals in the attached figures

[0035] 100: Stator assembly

[0036] 110: Stator core

[0037] 111: Stator teeth

[0038] 112: Stator slot

[0039] 113: Stator boot section

[0040] 120: Stator body

[0041] 130: Coil

[0042] 131: Upper stator coil

[0043] 132: Lower stator coil

[0044] 200: Rotor assembly

[0045] 210: Rotor core

[0046] 211: Block unit

[0047] 213: Block segment

[0048] 215: Block support component

[0049] 220: Permanent magnet

[0050] 221: First Pole Magnet

[0051] 222: Second pole magnet. Detailed Implementation

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. It is further understood that the terms “comprising” and / or “including” as used in this specification indicate the presence of the stated features, values, steps, operations, constituent elements, and / or components, but do not exclude the presence or addition of one or more other features, values, steps, operations, constituent elements, components, and / or combinations thereof. As used herein, the term “and / or” includes any one or all combinations of the associated listed items.

[0053] In the following detailed description, only certain embodiments of the invention are shown and described by way of illustration. However, the invention can be implemented in various ways and is not limited to the following embodiments.

[0054] The accompanying drawings and descriptions are intended to be illustrative rather than restrictive. Throughout the specification, the same reference numerals denote the same elements.

[0055] Furthermore, for the sake of understanding and ease of description, the dimensions and thicknesses of each configuration shown in the accompanying drawings are arbitrarily illustrated, but the invention is not limited thereto. In the drawings, the thicknesses of portions, films, plates, regions, etc., are enlarged for clarity.

[0056] The suffixes “module” and / or “unit” or “component” used for the components in the following description are provided for ease of writing instructions or are used interchangeably, and therefore they do not have different meanings or functions in themselves.

[0057] Furthermore, when describing the disclosed embodiments, detailed descriptions of relevant known technologies are omitted if it is determined that a detailed description would obscure the key points of the embodiments described in this specification.

[0058] Furthermore, the accompanying drawings are provided to facilitate understanding of the embodiments disclosed in this specification. The technical spirit disclosed in this specification is not limited to the drawings, and it should be understood that the invention includes all modifications, equivalents, and substitutions within the spirit and scope of the invention.

[0059] Terms including common designations (e.g., first and second) are used to describe various constituent elements, but the constituent elements are not limited by these terms.

[0060] In the following description, expressions described in the singular may be interpreted as either singular or plural, unless explicitly expressed as “a” or “single” is used.

[0061] The term is used only to distinguish one component from another.

[0062] When a component, device, element, etc. of the present invention is described as having a purpose or performing an operation or function, the component, device, or element shall be regarded herein as being "configured" to satisfy that purpose or perform that operation or function.

[0063] The axial flux motor according to the embodiment is described in detail below with reference to the accompanying drawings.

[0064] Figure 1 This is a perspective view showing the configuration of an axial flux motor according to the embodiment. Figure 2 It shows the basis Figure 1An exploded perspective view of the configuration of the axial flux motor in the proposed implementation scheme.

[0065] like Figure 1 and Figure 2 As shown, the axial flux motor (AFM) according to an embodiment of the present invention is an electric motor that guides magnetic flux axially, and is known to have higher torque and efficiency compared to the radial flux motor (RFM) that guides magnetic flux radially. Furthermore, compared to the radial flux motor, the axial flux motor allows for easier modularization and reduced size.

[0066] The axial flux motor according to the implementation scheme may include a stator assembly 100 and a rotor assembly 200.

[0067] The stator assembly 100 may include a stator core 110 and a coil 130 wound around the stator core 110.

[0068] The stator core 110 may include a plurality of stator teeth 111, stator slots 112 and stator shoe portions 113, each stator slot 112 being formed between stator teeth 111 and stator shoe portions 113 being formed at both ends of stator teeth 111.

[0069] The stator teeth 111 can be spaced apart at a predetermined interval in the circumferential direction. The stator teeth 111 can be formed at a predetermined distance in the radial direction. The stator teeth 111 can be channels for magnetic flux.

[0070] Stator slots 112 can be formed between stator teeth 111, and coils 130 can be wound therein.

[0071] The stator shoe portion 113 can extend from the radial inner end of the stator tooth portion 111 toward the stator slot 112. The stator shoe portion 113 can reduce the magnetic air gap.

[0072] The rotor assembly 200 may include a permanent magnet 220 and a rotor core 210.

[0073] Permanent magnets 220 can be disposed on both axial sides of stator assembly 100. Permanent magnets 220 can be arranged along the circumferential direction of stator assembly 100. Permanent magnets 220 may include a first pole magnet 221 and a second pole magnet 222. The first pole magnet 221 (e.g., N pole) and the second pole magnet 222 (e.g., S pole) may have different polarities. The first pole magnet 221 and the second pole magnet 222 can be arranged alternately along the circumferential direction at a predetermined interval.

[0074] like Figure 2As shown, the rotor core 210 can be disposed on the two outer axial sides of the permanent magnet 220 (i.e., the corresponding rotor core 210 is arranged on the outer axial sides of the corresponding set of permanent magnets 220). Therefore, the stator assembly 100 can be arranged in the center, the permanent magnets 220 can be arranged on the two axial sides of the stator assembly 100, and each rotor core 210 can be arranged on the outer axial sides of the two permanent magnets 220.

[0075] Figure 3 This is a perspective view showing the configuration of the rotor core 210 of the axial flux motor according to the embodiment.

[0076] refer to Figure 3 The rotor core 210 includes multiple block segments 213 stacked in the radial direction, each block unit 211 formed in an arc shape. The multiple block segments 213 are connected in the circumferential direction to form a rotor core 210 having an annular shape.

[0077] When multiple block segments 213 are connected along the circumferential direction to form an annular rotor core 210, the air gaps formed between the block segments 213 are filled with glass fiber reinforcement polymer (GFRP) material.

[0078] The block unit 211, which is formed in an arc shape, can have a set thickness in the radial direction. The diameter and circumferential length of the block unit 211, which is formed in an arc shape, can increase from the radially inner side to the radially outer side. Therefore, when multiple block units 211 are stacked in the radial direction, a fan shape with a cut-out central portion can be formed.

[0079] The rotor core 210 can be manufactured using electrical steel sheet. By using electrical steel sheet to manufacture the rotor core 210, iron losses caused by eddy currents generated in the rotor core 210 can be reduced, which can improve the efficiency of the axial flux motor.

[0080] Furthermore, when manufacturing each block unit of the block segment 213 constituting the rotor core 210, each block unit can be manufactured by axially stacking electrical steel plates of the same size, making the manufacturing of the block units easier.

[0081] When the permanent magnet 220 is arranged between the rotor core 210 and the stator assembly 100, the first pole magnet 221 can be arranged between the block segment 213 and the stator core 110, and the second pole magnet 222 can be arranged between the boundary of the block segment 213 and the stator core 110. In other words, the first pole magnet 221 can be arranged in the lower axial part of the circumferential center of the block segment 213, and the second pole magnet 222 can be arranged in the lower axial part of the connecting part of adjacent block segments 213.

[0082] In this case, the saturation of the back yoke of the rotor core 210 can be configured to be minimized at the boundary of the block segment 213.

[0083] For axial flux motors, the axial fluxes interlink while forming a closed loop. Because the flux in the rotor back yoke follows a predetermined path, relatively dense and relatively less dense flux regions repeat (or occur consecutively). For example, relatively dense and relatively less dense flux regions can repeat every 180 electrical degrees (see [link to relevant documentation]). Figure 4 and Figure 5 ).

[0084] In the rotor back yoke, relatively dense and relatively less dense magnetic flux regions appear consecutively. For example, these regions can be formed consecutively at 180-degree electrical angle intervals. In terms of the magnetic circuit, the less saturated portions of the back yoke have no significant impact on the motor's performance.

[0085] In the implementation, since the less saturated portion of the back yoke is configured to be located at the boundary of block segment 213, it can be seen that, from the perspective of the magnetic circuit, the effect on the motor magnetic circuit is minimal even when the rotor core 210 is connected by block segments 213 with block units 211 stacked in the radial direction.

[0086] For reference, analysis using the finite element method (FEM) confirms that the magnetic flux saturation at the boundary of block segment 213 is not significant. In other words, it can be seen that block segment 213, with angles that are multiples of 180 electrical degrees, does not affect the performance of the motor.

[0087] In the following, an axial flux motor according to another embodiment is described in detail with reference to the accompanying drawings.

[0088] Figure 6 This is a perspective view showing the configuration of an axial flux motor according to another embodiment. Figure 7 and Figure 8 It shows the basis Figure 6 An exploded perspective view of the configuration of the axial flux motor in the proposed implementation scheme.

[0089] Figures 6 to 8 The axial flux motor shown is the same as the one mentioned above. Figures 1 to 5 The difference in the axial flux motor lies only in the structure of the rotor assembly 200. Therefore, this is only in relation to the reference. Figures 1 to 5 The different components of the axial flux motor are described.

[0090] refer to Figures 6 to 8 According to another embodiment, the stator assembly 100 may include a stator body 120, an upper stator coil 131, and a lower stator coil 132.

[0091] The stator body 120 can be formed in the shape of a disk and can be configured as a printed circuit board (PCB).

[0092] The upper stator coil 131 can be wound on one surface (e.g., the upper surface) of the stator body 120. The lower stator coil 132 can be wound on another surface (e.g., the lower surface) of the stator body 120. In other words, the upper stator coil 131 can be wound on the upper surface of the stator body 120 with a very thin thickness, and the lower stator coil 132 can be wound on the lower surface of the stator body 120 with a very thin thickness. In other words, the stator assembly 100 can be implemented in the form of a PCB stator, wherein the stator coils 130 are formed on the upper and lower surfaces of the stator body 120, respectively.

[0093] The rotor assembly 200 arranged on each of the two axial sides of the stator assembly 100 has the same structure as described above, so a detailed description is omitted.

[0094] Figure 9 This is a perspective view showing the configuration of an axial flux motor according to yet another embodiment.

[0095] Figure 9 The axial flux motor shown is the same as the one mentioned above. Figures 1 to 5 The difference in the axial flux motor lies only in the structure of the rotor assembly 200. Therefore, this is only in relation to the reference. Figures 1 to 5 The different components of the axial flux motor are described.

[0096] refer to Figure 9 A block support member 215 may be formed at the lower part of the block section 213 of the rotor core 210. The block support member 215 may be formed to extend downward from the circumferential center of the block section 213.

[0097] When multiple block segments 213 are connected along the circumferential direction to form a ring shape, permanent magnets 220 can be arranged between the block support members 215. By arranging permanent magnets 220 between the block support members 215, the connection between the rotor core 210 and the permanent magnets 220 can be facilitated.

[0098] According to the embodiment of the axial flux motor, by applying electrical steel plates to the rotor core 210, the rotor core 210 exhibits superior BH characteristics (the relationship between current flux density B, demagnetizing force H, and maximum energy product BH) compared to a rotor core 210 using an SMC core (soft magnetic composite material core). Furthermore, each electrical steel plate forming the block segment 213 is stacked in an insulated state, which helps to reduce iron losses due to eddy currents.

[0099] The axial flux motor according to the disclosed embodiment can be applied to electric water pumps (EWPs) for vehicles.

[0100] By applying an axial flux motor according to the disclosed embodiment to an electric water pump, the axial dimension of the electric water pump can be minimized. Furthermore, by arranging the rotor assembly 200, including permanent magnets 220, on the upper and lower sides of the stator assembly 100, respectively, the torque of the drive motor can be increased within the confined space of the housing.

[0101] Although the invention has been described in conjunction with embodiments now regarded as practical implementations, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A rotor core, comprising: Multiple block units, forming an arc shape, The plurality of block units are stacked in the radial direction. The multiple block units are connected along the circumferential direction to form a ring shape.

2. The rotor core according to claim 1, wherein: The diameter and circumferential length of the plurality of block units increase from the radially inner side to the radially outer side.

3. An axial flux motor, comprising: A stator assembly comprising a stator core and coils wound around the stator core; A rotor assembly configured to rotate via electromagnetic interaction with the stator assembly. The rotor assembly includes: Permanent magnets are disposed on both axial sides of the stator assembly; The rotor core, each rotor core being disposed on the outer axial side of the permanent magnet, the rotor core comprising block segments having multiple block units stacked in the radial direction and formed in an arc shape, and the block segments being connected in the circumferential direction to form an annular shape.

4. The axial flux motor according to claim 3, wherein: The diameter and circumferential length of multiple block units of the rotor core increase from the radially inner side to the radially outer side.

5. The axial flux motor according to claim 3, wherein: The air gaps formed between the block sections are filled with glass fiber reinforced polymer material.

6. The axial flux motor according to claim 3, wherein: The permanent magnet includes a first pole magnet and a second pole magnet with a polarity different from that of the first pole magnet; The first and second pole magnets are arranged at equal intervals along the circumferential direction.

7. The axial flux motor according to claim 6, wherein: The first pole magnet is arranged between the block section and the stator core; The second pole magnet is arranged between the boundary of the block section and the stator core.

8. The axial flux motor according to claim 7, wherein: The saturation of the back yoke is minimized at the boundary of the block segment.

9. The axial flux motor according to claim 3, wherein, The stator core includes: The stator teeth are spaced apart at predetermined intervals along the circumferential direction; Stator slots, each stator slot being formed between stator teeth, with coils wound in the stator slots; and The stator shoe extends radially inward from the stator teeth toward the stator slot.

10. The axial flux motor according to claim 3, wherein, The stator assembly includes: stator body; Upper stator coils, which are wound on the upper surface of the stator body; and The lower stator coil is wound on the lower surface of the stator body.

11. The axial flux motor according to claim 3, further comprising a block support member formed in the lower part of the block section of the rotor core.

12. The axial flux motor according to claim 11, wherein, The permanent magnets are arranged between the block support members.

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