Rotor assembly and axial flux machine

Abstract

The utility model relates to a rotor assembly and axial flux motor including the rotor assembly. The rotor assembly rotor framework, a plurality of magnetic steel body, sheath and fixed component. Rotor framework includes framework main part and a plurality of stem parts, the plurality of stem parts from the framework main part along the radial direction outward extension and along the framework main part's periphery interval arrangement, be arranged with the magnetic steel body in radial direction direction and extend beyond the stem part between every two adjacent stem parts, the sheath surrounds the rotor framework and leans on the magnetic steel body in radial direction direction, wherein, the sheath and every stem part's radial direction outer circumference have first gap, every the magnetic steel body and rotor framework have second gap with first gap intercommunication, the fixed component occupies all first gap and second gap. The utility model's rotor assembly can realize the reliable positioning of rotor framework and magnetic steel body in axial and radial, and has improved the stress concentration on rotor framework and sheath.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a rotor assembly and an axial flux motor including the rotor assembly. Background Technology

[0002] Axial flux motors (AFMs) are gaining increasing attention in the new energy vehicle industry due to their compact axial dimensions, smaller size, lighter weight, and ability to deliver greater torque and power. They offer stronger drive torque in a smaller and lighter structure. Because of the large diameter and weight of the magnets in AFMs, the rotor experiences significant radial centrifugal force during high-speed operation. Therefore, the rotor structure design must ensure reliable radial fixation of the magnets to overcome this enormous radial centrifugal force. Furthermore, the asymmetric axial magnetic field in AFMs results in asymmetrical axial magnetic pull on the rotor, making reliable axial fixation of the magnets another crucial aspect.

[0003] Existing axial flux motors typically employ a one-piece metal rotor frame. However, the metal frame suffers from eddy current losses due to alternating magnetic fields, negatively impacting motor efficiency. Furthermore, overcoming stress issues in the rotor frame often necessitates the use of high-strength structural steel, resulting in very high manufacturing costs. However, under high-speed rotation conditions (especially up to 10,000 rpm), centrifugal forces reach significant levels, rendering even high-strength steel metal frames insufficient to meet performance requirements. Therefore, an improved rotor assembly, particularly suitable for axial flux motors, is needed. Utility Model Content

[0004] The purpose of this utility model is to solve at least one of the above-mentioned problems and / or other problems existing in the prior art.

[0005] To achieve the above objectives, according to one aspect of the present invention, a rotor assembly is provided, the rotor assembly comprising: a rotor frame, the rotor frame including a frame body and a plurality of rods, the frame body being annular, the plurality of rods extending radially outward from the frame body and arranged at circumferential intervals along the frame body; a plurality of magnets, one magnet being arranged between every two adjacent rods, each magnet being arranged to extend radially beyond the rod; and a sheath surrounding the rotor frame and abutting against the plurality of magnets in the radial direction; wherein a first gap exists between the sheath and the radial outer periphery of each rod, and a second gap exists between each magnet and the rotor frame, the first gap communicating with the second gap; the rotor assembly further comprising a fixing member occupying all of the first and second gaps.

[0006] In one embodiment, the rotor frame is made of a non-metallic material, and the sheath is made of carbon fiber material.

[0007] In one embodiment, the fixing member is formed by potting resin material within all the first and second gaps to fix the rotor frame, the magnet body, and the sheath together.

[0008] In one embodiment, each magnet is fan-shaped and includes a first side edge, a second side edge, and a radial outer peripheral edge and a radial inner peripheral edge connecting the first side edge and the second side edge.

[0009] In one embodiment, each magnet has two opposing rounded corners at the positions where its first and second side edges meet the radial outer peripheral edge, respectively. Each rod has two stop points symmetrically arranged about the central axis of the rod at its end away from the main frame. The rounded corners of the magnet abut against the stop points of the adjacent rod through the fixing member, and the stop points are spaced apart from the sheath through the fixing member.

[0010] In one embodiment, the fixing member includes an outer peripheral section arranged in a first gap for at least spaced apart from the stop tip from the sheath and extending circumferentially.

[0011] In one embodiment, a radial gap is formed between the first and second side edges of each magnet and the adjacent rod portion, and the fixing member further includes a radial portion arranged in the radial gap and connected to the outer peripheral portion.

[0012] In one embodiment, a circumferential gap is formed between the radial inner peripheral edge of each magnet and the frame body, and the fixing member also includes an inner peripheral segment connected to the radial segment and arranged in the circumferential gap; the radial gap and the circumferential gap constitute the second gap; all the outer peripheral segments, radial segments and inner peripheral segments are connected to each other to form a whole and together constitute the fixing member.

[0013] In one embodiment, the rod portion and the main body of the rotor frame are respectively provided with chamfered portions in the parts adjacent to the corresponding magnets, and the radial and inner peripheral sections of the fixing member are respectively provided with protruding edges that are complementary to the chamfered portions on the corresponding rod portion and the main body of the frame.

[0014] According to another aspect of the present invention, an axial flux motor is provided, which includes a rotor assembly as described above.

[0015] The rotor assembly of this invention comprises a main frame and multiple rods extending radially outward from the main frame, resulting in an open frame structure. A sheath is used to position the magnets and rotor frame radially, and a fixing component is used to position them axially. The use of a non-metallic rotor frame and a carbon fiber sheath not only avoids eddy current losses but also significantly improves stress concentration in both the rotor frame and sheath. The fixing component further isolates the rotor frame from the magnets and sheath, further reducing stress concentration in both components. Attached Figure Description

[0016] The features and advantages of this utility model will become clear from the following detailed description provided with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and therefore should not be considered as limitations on this utility model, wherein:

[0017] Figure 1 A perspective view of a rotor assembly according to an embodiment of the present invention is shown.

[0018] Figure 2 Show Figure 1 An exploded view of the rotor assembly shown.

[0019] Figure 3 A stress simulation diagram of a rotor frame according to the prior art is shown, the rotor frame being made of a metallic material and having a closed outer perimeter.

[0020] Figure 4a and Figure 4b Shown in Figure 3The diagram shows a stress simulation of the rotor frame and the sheath surrounding the rotor frame, which is an improved version of the prior art. The rotor frame is made of metal and has a closed outer periphery.

[0021] Figure 5a and Figure 5b Show Figure 1 Stress simulation diagram of the rotor frame and rotor assembly.

[0022] Figure 6 Show Figure 1 A partial exploded view of the rotor frame, magnets, and fixing components of the rotor assembly shown.

[0023] Figure 7 Show Figure 1 The rotor assembly shown is a partial cross-sectional view along line AA.

[0024] Figure 8 Show Figure 1 A partial schematic diagram of the fixing components of the rotor assembly shown. Detailed Implementation

[0025] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0026] The terms "first" and "second" are used below to describe the elements of this application. These terms are used only to distinguish the individual elements and not to limit the nature, order, or number of these elements. The terms "comprising" and "having" are used to indicate an open-ended inclusion and mean that there may be additional elements / components besides those listed.

[0027] An axial flux motor typically includes a stator assembly, a rotor assembly, and a motor shaft passing through both the stator and rotor assemblies. The number of stator and rotor assemblies can be configured according to actual needs. For example, common structural forms include a dual-stator single-rotor structure, a dual-rotor single-stator structure, or a multi-rotor / multi-stator modular design. In an axial flux motor, the stator and rotor assemblies can each be shaped like roughly flattened disks, with magnetic lines of force passing through the air gap between the stator and rotor assemblies along the axial direction. Figures 1 to 2 A rotor assembly according to one embodiment of the present invention is shown. This rotor assembly can be used, in particular, in axial flux motors. In this embodiment, it can be used as... Figure 1 The rotor assembly shown can be provided with a stator assembly on one side to form a single rotor and single stator structure. Alternatively, stator assemblies can be provided on both sides of the rotor assembly along the axial direction to form a double stator and single rotor structure.

[0028] like Figure 1 and Figure 2 As shown, the rotor assembly according to this embodiment may include a rotor frame 1, a plurality of magnets 2, a sheath 3 and a fixing member 4, wherein the magnets 2 are arranged on the rotor frame 1, and the sheath 3 and the fixing member 4 are used together to fix the magnets 2 radially and axially.

[0029] Figure 3 A known integral rotor frame 10' is shown, made of metal and having multiple fan-shaped mounting openings into which multiple magnets are embedded. The rotor frame 10' has a closed structure on its outer periphery. Under specific operating conditions, such as a set of magnets experiencing a centrifugal force of 28471 N at 12000 RPM, stress simulation results under this condition show that the stress can reach up to 1634 MPa at, for example, the corner regions of the mounting openings for the magnets. This makes it impossible for even high-strength steel to meet the structural strength requirements.

[0030] To address both the eddy current losses caused by metallic materials and the stress concentration problem in the rotor frame, the applicant proposes an improved non-metallic rotor frame 20' based on the existing rotor frame 10' (e.g., Figure 4a As shown), it replaces the metallic material in the prior art with a non-metallic material and adds, for example, to the outer periphery of the rotor frame 20'. Figure 4b The ring-shaped sheath 30' shown is made of carbon fiber material. Figure 4b (Only one section of the sheath is shown in the image). Under the same operating conditions, stress simulation results show that the maximum stress on the rotor frame 20' is from... Figure 3 The pressure of 1634 MPa shown decreased to Figure 4aThe stress of 112 MPa, as shown, significantly reduces the stress on the rotor frame. However, in this design, the sheath 30' is subjected to a stress of 2038 MPa, as... Figure 4b As shown, this poses a significant challenge for carbon fiber materials.

[0031] Therefore, in order to further address the stress problem of the sheath, the applicant subsequently proposed an improved rotor assembly, such as... Figure 1 and Figure 2 As shown. See especially. Figure 2 The rotor frame 1 includes a frame body 11 and a plurality of rods 12. The frame body 11 is generally annular, thus having a shaft hole in the center through which the motor shaft passes. The frame body 11 has a plurality of mounting holes spaced circumferentially along this shaft hole for securing the rotor assembly to the motor shaft using fasteners passing through these mounting holes, allowing the rotor assembly to rotate with the motor shaft. Unlike... Figure 3 and Figure 4a The rotor frame shown is Figure 1-2 In the embodiment shown, multiple rods 12 of the rotor skeleton are arranged at intervals along the circumference of the skeleton body 11 and extend radially outward from the outer periphery of the skeleton body 11, so that these rods 12 and the skeleton body 11 as a whole form a sun gear shape, thus forming an open skeleton structure.

[0032] like Figure 2 As shown, a roughly fan-shaped region is formed between two adjacent rods 12. The magnet 2 can also be roughly fan-shaped to fit the fan-shaped region between each pair of adjacent rods 12. This allows multiple magnets 2 to be arranged at intervals along the circumference of the rotor frame 1. The sheath 3 is roughly annular, thus surrounding the outer periphery of the rotor frame 1 and abutting against the radially outer end of each magnet 2 in the radial direction of the rotor frame 1, such as... Figure 1 As shown. The sheath 3 provides radial fastening force to the magnet body 2.

[0033] Each magnet 2 is clearance-fitted with the rotor frame 1 in a fan-shaped region and is arranged to extend radially beyond the rod portion 12. Specifically, the radially outer end of each magnet 2 extends radially beyond the rod portion 12 in the rotor assembly. Thus, a first gap is formed between the sheath 3 and the radially outer periphery of each rod portion 12, and a second gap is formed between each magnet 2 and the rotor frame 1, the first and second gaps being interconnected. A fixing member 4 occupies / fits in all the first and second gaps, thereby isolating the rotor frame 1 from the magnets 2 and the sheath 3 respectively by means of the fixing member 4, and also enabling axial positioning of the rotor frame 1 and the plurality of magnets 2 by means of the fixing member.

[0034] Unlike existing rotor assemblies that use a one-piece metal rotor frame, the rotor frame according to an embodiment of the present invention can be made of a non-metallic material (such as polyphenylene sulfide, PPS), which reduces the weight of the rotor assembly, thereby reducing the inertial force of the rotor assembly and saving costs. By providing a sheath made of, for example, carbon fiber material around the outer periphery of the rotor frame, more reliable radial positioning between the multiple magnets and the rotor frame can be achieved. On the other hand, this non-metallic open frame combined with a carbon fiber sheath according to the present invention not only avoids eddy current losses compared to the prior art, but also significantly improves the stress concentration of the rotor frame and the sheath.

[0035] For example, Figure 5a and Figure 5b Showing the target Figure 1 The stress simulation results of the rotor assembly are shown. The maximum stress caused by centrifugal force on rotor frame 1 is from... Figure 4a The pressure decreased from 112 MPa to Figure 5a The pressure below 30 MPa shown (it should be understood that, Figure 5a The location of maximum stress is at the bolt mounting point, and this stress is not tensile stress caused by centrifugal force. Additionally, the maximum stress on sleeve 3 also originates from... Figure 4b The 2038 MPa was reduced to Figure 5b The 1358MPa shown represents a significant improvement.

[0036] See back Figure 1 and Figure 2 The fixing component 4 can be a fixing structure formed by filling all the first and second gaps with resin material in the form of potting. After the potting resin material cures, it allows the rotor frame 1, magnet body 2 and sheath 3 to be firmly fixed together.

[0037] like Figure 2 As shown, each magnet 2 may include a first side edge and a second side edge extending radially, as well as a radially outer peripheral edge away from the frame body and a radially inner peripheral edge close to the frame body. Therefore, the radially outer peripheral edge connects the radially outer ends of the first and second side edges, and the radially inner peripheral edge connects the radially inner ends of the first and second side edges. Each magnet 2 may be fan-shaped, and multiple magnets 2 are uniformly arranged circumferentially along the rotor assembly.

[0038] See also Figure 6 It shows Figure 1 The diagram shows a partial exploded view of the rotor assembly, including the rotor frame, multiple magnets, and fixing components. (See attached image.) Figure 6As shown, each magnet 2 has two opposing rounded corners 21 at the positions where its first and second side edges meet the radial outer peripheral edge, respectively. Each rod 12 has two stop points 121 at its end opposite to the frame body 11. The two stop points 121 are arranged symmetrically about the central axis of the rod and extend in opposite directions along the circumference of the rotor frame 1, such that each stop point 121 can extend to the radially outer side of the corresponding rounded corner 21. The rounded corner 21 of the magnet 2 abuts against the stop point 121 of the adjacent rod 12 by a part of the fixing member 4, and the stop point 121 is spaced apart from the sheath 3 by another part of the fixing member 4. This arrangement is very advantageous because it avoids direct contact between the sheath made of carbon fiber material and the sharp parts of the rotor frame (such as the stop points), thus advantageously reducing stress concentration in the sheath.

[0039] refer to Figure 2 and Figure 6 As shown, the fixing member 4 may include an outer peripheral section 41, a radial section 42, and an inner peripheral section 43 (see...). Figure 2 The number of outer peripheral segments 41 of the fixing member 4 corresponds one-to-one with the rod 12. Each outer peripheral segment 41 is arranged in a corresponding first gap and extends circumferentially along the rotor frame 1, thereby separating the radial outer periphery of the two stop points 121 of the rod from the sheath 3.

[0040] Radial gaps are formed between the first side edge of each magnet 2 and the adjacent rod 12, and between its second side edge and the adjacent rod 12. The number of radial segments 42 of the fixing member 4 can be set to twice the number of magnets 2, that is, every two radial segments 42 correspond to one magnet 2. The two radial segments 42 are connected to the outer peripheral segments 41 and arranged in the corresponding radial gaps, thereby separating the rod 12 and its corresponding magnet 2.

[0041] A circumferential gap is formed between the radial inner peripheral edge of each magnet 2 and the main frame 11, and each inner peripheral segment 43 corresponds to the radial inner peripheral edge of one magnet 2. Each inner peripheral segment 43 extends circumferentially along the rotor frame 1, and this inner peripheral segment 43 connects to two radial segments 42 corresponding to the same magnet 2. The radial and circumferential gaps between the magnet 2 and the rotor frame 1 constitute a second gap. Figure 2 As shown, all the outer peripheral sections 41, inner peripheral sections 43 and radial sections 42 are connected into a whole, thus forming the entire fixed component 4.

[0042] Figure 7 A partial sectional view of the rotor frame, magnet body, and fixing member according to this embodiment is shown. Figure 2 , Figure 7 and Figure 8 As shown, the rod portion 12 and the main body 11 of the rotor frame 1 each have a chamfered portion 13 on the portion adjacent to the corresponding magnet. The radial section 42 of the fixing member 4 has a protruding edge 44 complementary to the chamfered portion 13 on the rod portion 12, and the inner peripheral section 43 has a protruding edge 44 complementary to the chamfered portion 13 on the main body 11. These protruding edges help to position the fixing member 4 and the magnet 2 relative to the rotor frame 1 in the axial direction. Optionally, the minimum cross-sectional area of ​​the fixing member 4 is 45 mm². 2 This allows for the positioning of the rotor frame 1 and the magnet body 2 by providing an axial force of over 2000N.

[0043] The rotor assembly of this invention comprises a main frame and multiple rods extending radially outward from the main frame, resulting in an open frame structure. A sheath is used to position the magnets and rotor frame radially, and a fixing component is used to position them axially. The use of a non-metallic rotor frame and a carbon fiber sheath not only avoids eddy current losses but also significantly improves stress concentration in both the rotor frame and sheath. The fixing component further isolates the rotor frame from the magnets and sheath, further reducing stress concentration in both components.

[0044] Various modifications and variations can be made to the embodiments disclosed above without departing from the scope or spirit of this invention. Other embodiments of this invention will be apparent to those skilled in the art based on the practice of this invention disclosed in this specification. This specification and the examples disclosed herein should be considered illustrative only, and the true scope of this invention is defined by the appended claims and their equivalents.

Claims

1. A rotor assembly, characterized in that, The rotor assembly includes: The rotor frame (1) includes a frame body (11) and a plurality of rods (12). The frame body is circular, and the plurality of rods extend radially outward from the frame body and are arranged at intervals along the circumference of the frame body. Multiple magnets (2), one magnet is arranged between every two adjacent rods, each magnet being arranged to extend radially beyond the rod; and Sheath (3), the sheath surrounds the rotor frame and abuts against the plurality of magnets in the radial direction; The sheath (3) has a first gap between its radial outer periphery and that of each rod (12), and each magnet (2) has a second gap between its radial outer periphery and that of the rotor frame (1). The first gap is connected to the second gap. The rotor assembly also includes a fixing member (4) which occupies all of the first gap and the second gap.

2. The rotor assembly according to claim 1, characterized in that, The rotor frame (1) is made of non-metallic material, and the sheath (3) is made of carbon fiber material.

3. The rotor assembly according to claim 2, characterized in that, The fixing member is formed by potting resin material within all the first and second gaps to fix the rotor frame, the magnet body and the sheath together.

4. The rotor assembly according to any one of claims 1 to 3, characterized in that, Each magnet (2) is fan-shaped and includes a first side edge, a second side edge, and a radial outer peripheral edge and a radial inner peripheral edge connecting the first side edge and the second side edge.

5. The rotor assembly according to claim 4, characterized in that, Each magnet (2) has two opposing rounded corners (21) at the positions where the first and second side edges meet the radial outer peripheral edge, respectively. Each rod (12) has two stop points (121) symmetrically arranged about the central axis of the rod at its end away from the main frame. The rounded corners of the magnet abut against the stop points of the adjacent rod through the fixing member, and the stop points are separated from the sheath by the fixing member.

6. The rotor assembly according to claim 5, characterized in that, The fixing member (4) includes an outer peripheral section (41) arranged in the first gap for at least spaced apart from the stop tip from the sheath and extending circumferentially.

7. The rotor assembly according to claim 6, characterized in that, Each magnet has a radial gap between its first and second side edges and the adjacent rod portion, and the fixing member (4) also includes a radial section (42) connected to the outer peripheral section and arranged in the radial gap.

8. The rotor assembly according to claim 7, characterized in that, Each magnet has a circumferential gap between its radial inner edge and the frame body. The fixing member (4) also includes an inner circumferential section (43) connected to the radial section (42) and arranged in the circumferential gap. The radial gap and the circumferential gap constitute the second gap. All the outer circumferential sections, radial sections and inner circumferential sections are connected to each other to form a whole and together constitute the fixing member.

9. The rotor assembly according to claim 8, characterized in that, The rod portion (12) and the frame body (11) of the rotor frame (1) are respectively provided with chamfered portions (13) in the portions adjacent to the corresponding magnets. The radial portion (42) and the inner peripheral portion (43) of the fixing member are respectively provided with protruding edges (44) that are complementary to the chamfered portions on the corresponding rod portion (12) and the frame body (11).

10. An axial flux motor, characterized in that, The axial flux motor includes a rotor assembly according to any one of claims 1 to 9.

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