A rotor assembly and an axial flux electric machine

Abstract

The utility model belongs to motor technical field discloses a rotor assembly and axial flux motor. The rotor assembly includes back iron, the opposite sides of back iron all are equipped with inner chamber, all are provided with a plurality of magnetic steel in each inner chamber, a plurality of magnetic steel of each side all along the equidistant arrangement of back iron's circumference, the opposite sides of back iron still are provided with the pressing plate respectively, the pressing plate is pressed to be established on a plurality of magnetic steel and is connected with back iron, the inner wall of each inner chamber all is equipped with cooling channel, the cooling channel is used for the medium for going in cooling to cool back iron and the plurality of magnetic steel of both sides. The utility model provides rotor assembly and axial flux motor, can reduce the eddy current loss of rotor assembly simultaneously to the magnetic steel and back iron direct oil liquid cooling, has improved the heat dissipation efficiency of rotor assembly, guarantees the stable operation of axial flux motor.

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. Background Technology

[0002] An axial flux motor is a type of motor in which the magnetic field is distributed along the motor axis. Unlike traditional radial flux motors, axial flux motors have a disc-shaped structure. Due to their compact structure, small size, light weight, and high torque density, they are widely used in the market.

[0003] Traditional dual-stator single-rotor axial flux motors typically use a cage-supported rotor assembly with magnets inserted into it. Since the cage is mostly made of resin, it has disadvantages such as low stiffness, easy deformation, and low thermal conductivity, making it unsuitable for high-speed environments with high requirements for heat dissipation and strength. Related technologies use metal back irons to replace resin cages to support the magnets. Although metal back irons have the advantages of high thermal conductivity and high stiffness, they increase eddy current losses. The increased losses will increase the heat generation of the rotor assembly, thereby raising the temperature of the rotor assembly. Excessive temperature rise can cause irreversible demagnetization of the magnets, affecting the stable operation of the motor.

[0004] Therefore, there is an urgent need to provide a rotor assembly and an axial flux motor to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide a rotor assembly and an axial flux motor that can directly cool the magnets and back iron with oil while reducing eddy current losses in the rotor assembly, thereby improving the heat dissipation efficiency of the rotor assembly and ensuring the stable operation of the axial flux motor.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A rotor assembly includes a back iron, with inner cavities on opposite sides of the back iron. Each inner cavity contains a plurality of magnets, which are evenly spaced along the circumference of the back iron. Pressure plates are also provided on opposite sides of the back iron, pressing against the plurality of magnets and connected to the back iron. Cooling channels are formed on the inner walls of each inner cavity, through which a cooling medium is introduced to cool the back iron and the plurality of magnets on both sides.

[0008] As an optional solution, the back iron includes a disc body, a rotating shaft, and a retaining ring. The disc body is arranged around the outer periphery of the rotating shaft, and the retaining ring is arranged around the outer periphery of the disc body and together with the disc body, defines two inner cavities. The rotating shaft, the disc body, and the retaining ring are integrally formed, and the pressure plate is sleeved on the outside of the rotating shaft.

[0009] As an optional solution, the rotating shaft is provided with an oil inlet hole and an oil outlet hole. The cooling channel includes an oil inlet straight groove, an oil outlet straight groove, and multiple annular grooves formed on the disc body. The multiple annular grooves are arranged coaxially at intervals along the radial direction of the disc body. The oil inlet straight groove and the oil outlet straight groove are arranged at intervals along the circumference of the disc body and both extend radially along the disc body. One end of the oil inlet straight groove is connected to the oil inlet hole, and the other end of the oil inlet straight groove is connected to the multiple annular grooves. One end of the oil outlet straight groove is connected to the oil outlet hole, and the other end of the oil outlet straight groove is connected to the multiple annular grooves.

[0010] As an optional solution, the cooling channel further includes a retaining ring groove, which is formed on the inner sidewall of the retaining ring and extends circumferentially along the retaining ring. The oil inlet straight groove and the oil outlet straight groove are both connected to the retaining ring groove.

[0011] As an optional solution, the pressure plate includes an annular portion and a plurality of clamping arms. The plurality of clamping arms are evenly connected to the outer periphery of the annular portion along the circumference of the annular portion. The number of clamping arms is the same as the number of magnets. There is a gap between two adjacent magnets. Each clamping arm is accommodated in the corresponding gap and clamps the sides of the magnets on both sides.

[0012] As an alternative, the magnet is fan-shaped, and a first inclined pressing surface is formed on the two straight edges of the magnet away from the back iron. A second inclined pressing surface is formed on the two straight edges of the clamping arm corresponding to the magnet. The second inclined pressing surface has the same inclination angle as the first inclined pressing surface and they are in a corresponding pressing fit.

[0013] As an alternative, the pressure plate is fixed to the back iron by countersunk bolts.

[0014] As an alternative, the surface of the pressure plate away from the back iron is lower than the outer surface of the magnet, and the end face of the countersunk bolt away from the back iron is not higher than the outer surface of the magnet.

[0015] As an alternative, the magnet is attached to the bottom of the inner cavity by adhesive bonding.

[0016] An axial flux motor includes two stator assemblies and a rotor assembly as described above, the rotor assembly being disposed between the two stator assemblies.

[0017] The beneficial effects of this utility model are:

[0018] This invention provides a rotor assembly and an axial flux motor. A metal back iron replaces the resin cage to support the magnets. While the metal back iron has advantages of high thermal conductivity and high rigidity, it increases eddy current losses. Therefore, this invention opens cooling channels on both sides of the back iron, using slots to block potentially large eddy current loops, confining the eddy currents to these narrow areas, thus reducing eddy current intensity and losses. Furthermore, the cooling channels on both sides, together with the corresponding magnets and pressure plates, form closed oil channels. By introducing cooling medium into these channels, the back iron and the magnets on both sides can be directly cooled with oil, improving the heat dissipation efficiency of the rotor assembly and ensuring stable operation of the axial flux motor. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the rotor assembly provided in an embodiment of the present invention;

[0020] Figure 2 This is an exploded view of the rotor assembly provided in this embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the back iron structure provided in an embodiment of the present utility model;

[0022] Figure 4 This is a radial sectional view of the back iron provided in an embodiment of the present utility model;

[0023] Figure 5 This is a radial sectional view of the rotor assembly provided in this embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of the structure of the magnet provided in this embodiment of the utility model;

[0025] Figure 7 This is a schematic diagram of the pressure plate provided in an embodiment of the present invention.

[0026] In the picture:

[0027] 10. Back iron; 11. Plate body; 111. Oil inlet straight groove; 112. Oil outlet straight groove; 113. Annular groove; 12. Shaft; 121. Oil inlet hole; 122. Oil outlet hole; 13. Retaining ring; 131. Retaining ring groove; 14. Inner cavity; 15. Cooling channel;

[0028] 20. Magnet; 21. First inclined pressure surface;

[0029] 30. Pressure plate; 31. Circular part; 32. Clamping arm; 321. Second inclined pressure surface; 322. Countersunk hole;

[0030] 40. Countersunk bolts. Detailed Implementation

[0031] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar parts or parts having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0032] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0033] In the description of this utility model, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 and Figure 2As shown, this embodiment provides a rotor assembly, including a back iron 10. The back iron 10 serves as the output part of the rotor assembly, used to output the power of the rotor assembly. Each side of the back iron 10 has an inner cavity 14, and each inner cavity 14 contains multiple magnets 20. The multiple magnets 20 on each side are evenly spaced along the circumference of the back iron 10. Each side of the back iron 10 also has a pressure plate 30, which presses against the multiple magnets 20 and connects to the back iron 10. The back iron 10 and the pressure plate 30 together axially limit the magnets 20, restricting their axial displacement and preventing them from attracting the stator assembly and forming a suction cup. Each inner cavity 14 has a cooling channel 15 on its inner wall, through which a cooling medium is introduced to cool the back iron 10 and the multiple magnets 20 on both sides. The pressure plates 30 on both sides of the back iron 10 have the same structure, and the magnets 20 on both sides of the back iron 10 have the same structure. Furthermore, multiple magnets 20 on both sides are symmetrically attached to both sides of the back iron 10.

[0036] The rotor assembly provided in this embodiment uses a metal back iron 10 to replace the resin cage to support the magnets 20. The metal back iron 10 has the advantages of high thermal conductivity and high rigidity, but it will increase eddy current losses. Therefore, this embodiment opens cooling channels on both sides of the back iron 10. The channels are slotted to block the large area of ​​eddy current loops that might otherwise be formed, so that the eddy currents are confined to these narrow areas, thereby reducing the intensity of the eddy currents and reducing eddy current losses. In addition, the cooling channels on both sides, together with the magnets 20 and the pressure plate 30 on the corresponding sides, form a closed oil passage. By introducing a cooling medium (hydraulic oil) into the oil passage, the back iron 10 and the magnets 20 on both sides can be directly cooled by oil, which improves the heat dissipation efficiency of the rotor assembly and ensures the stable operation of the axial flux motor.

[0037] In this embodiment, the back iron 10 is made of steel with magnetic and electrical properties, such as 45 steel; the pressure plate 30 is made of a non-magnetic and non-conductive resin composite material with high structural strength.

[0038] Optionally, such as Figure 2 and Figure 3 As shown, the back iron 10 includes a disc body 11, a rotating shaft 12, and a retaining ring 13. The disc body 11 is arranged around the outer periphery of the rotating shaft 12, and the retaining ring 13 is arranged around the outer periphery of the disc body 11, together with the disc body 11 defining two inner cavities 14. The pressure plate 30 is sleeved on the outside of the rotating shaft 12. Specifically, the magnet 20 and the pressure plate 30 are both located in the inner cavity 14. The outer peripheral surfaces of the magnet 20 and the pressure plate 30 abut against the retaining ring 13, the inner peripheral surface of the pressure plate 30 abuts against the rotating shaft 12, and the inner peripheral surface of the magnet 20 abuts against the pressure plate 30, thereby achieving radial limiting of the pressure plate 30 and the magnet 20, resisting the centrifugal force generated during rotation, and thus improving the stability of the rotor assembly.

[0039] In this embodiment, the rotating shaft 12, the disc body 11, and the retaining ring 13 are integrally formed. The integral forming process reduces the number of steps and material waste in the production process by completing the entire part in one mold, thereby significantly reducing production costs and improving structural stability and production efficiency.

[0040] In an optional embodiment, such as Figure 3 As shown, the rotating shaft 12 has an oil inlet hole 121 and an oil outlet hole 122, both extending along the axial direction of the rotating shaft 12. The cooling channels 15 on both sides of the back iron 10 are symmetrically arranged and have identical structures. Taking one side of the cooling channel 15 as an example... Figure 3 As shown, the cooling channel 15 includes an oil inlet straight groove 111, an oil outlet straight groove 112, and a plurality of annular grooves 113 formed on the disc body 11. The plurality of annular grooves 113 are arranged coaxially at intervals along the radial direction of the disc body 11. The oil inlet straight groove 111 and the oil outlet straight groove 112 are arranged at intervals along the circumference of the disc body 11 and both extend radially along the disc body 11. In this embodiment, the oil inlet straight groove 111 and the oil outlet straight groove 112 are arranged adjacent to each other and are blocked from each other. One end of the oil inlet straight groove 111 is connected to the oil inlet hole 121, and the other end of the oil inlet straight groove 111 is connected to the plurality of annular grooves 113. One end of the oil outlet straight groove 112 is connected to the oil outlet hole 122, and the other end of the oil outlet straight groove 112 is connected to the plurality of annular grooves 113. After the magnet 20 and the pressure plate 30 are housed in the inner cavity 14, the back of the magnet 20 and the back of the pressure plate 30 are in contact with the bottom of the inner cavity 14, thus forming a closed oil passage together with the oil inlet straight groove 111, the oil outlet straight groove 112 and multiple annular grooves 113 for the flow of cooling medium.

[0041] Furthermore, such as Figure 3 As shown, the cooling channel 15 also includes a retaining ring groove 131, which is formed on the inner side wall of the retaining ring 13 and extends along the circumference of the retaining ring 13. The oil inlet straight groove 111 and the oil outlet straight groove 112 are both connected to the retaining ring groove 131.

[0042] Combination Figure 4 and Figure 5During heat dissipation, the cooling medium flows from the oil inlet hole 121 into the oil inlet straight groove 111. The cooling medium flowing in the oil inlet straight groove 111 can be quickly distributed to each annular groove 113 and the retaining ring groove 131, and flows clockwise in the annular groove 113 and the retaining ring groove 131. The oil flowing in the annular groove 113 can directly cool the bottom surface of the magnets 20 on both sides, and the oil flowing in the retaining ring groove 131 can directly cool the outer circumferential surface of the magnets 20 on both sides. Then it flows into the oil outlet straight groove 112 and finally flows out through the oil outlet hole 122. Since the cooling oil flows in the groove opened on the back iron 10, it also directly cools the back iron 10, thereby efficiently and comprehensively cooling each magnet 20 and the back iron 10, improving the heat dissipation efficiency of the rotor assembly. In addition, by opening annular grooves 113 and straight grooves on the back iron 10, it is possible to block the large-area eddy current loop that might otherwise be formed, so that the eddy current is confined to these narrow areas, thereby weakening the eddy current intensity, reducing eddy current loss, reducing the heat generation of the back iron 10, and improving efficiency.

[0043] In this embodiment, four annular grooves 113 are provided, which increases the contact area between the cooling oil and the magnet 20. The cooling oil flows regularly along each annular groove 113 in a predetermined direction, which can further improve the cooling efficiency of the cooling oil on the magnet 20 and the back iron 10, and improve the heat dissipation efficiency of the rotor assembly. In other optional embodiments, the number of annular grooves 113 can also be set, which can be flexibly set according to actual needs, and no specific limitation is made here.

[0044] In an optional embodiment, such as Figure 7 As shown, the pressure plate 30 includes an annular portion 31 and a plurality of clamping arms 32. The annular portion 31 is sleeved on the outside of the rotating shaft 12. The plurality of clamping arms 32 are evenly connected to the outer periphery of the annular portion 31 along the circumference. The number of clamping arms 32 is the same as the number of magnets 20. There is a gap between two adjacent magnets 20. Each clamping arm 32 is accommodated in the corresponding gap and clamps the sides of the magnets 20 on both sides. That is, each clamping arm 32 has magnets 20 on both sides of its circumference, and each clamping arm 32 clamps the sides of two magnets 20 on its circumference, thereby limiting the magnets 20 axially.

[0045] In this embodiment, each magnet 20 is attached to the bottom of the inner cavity 14 by adhesive bonding, and is distributed in a circumferential array, symmetrically attached to both sides of the back iron 10 and positioned by tooling.

[0046] Combination Figure 6 and Figure 7In this embodiment, the magnet 20 is fan-shaped. A first inclined pressing surface 21 is formed on the two straight edges of the magnet 20 away from the back iron 10. The first inclined pressing surface 21 gradually slopes inwards along the direction away from the back iron 10. A second inclined pressing surface 321 is formed on the two straight edges of the clamping arm 32 corresponding to the magnet 20. The second inclined pressing surface 321 has the same inclination angle as the first inclined pressing surface 21 and they are in a corresponding pressing fit. Through the pressing fit between the first inclined pressing surface 21 and the second inclined pressing surface 321, the axial positioning of the magnet 20 is achieved.

[0047] In this embodiment, as Figure 1 and Figure 2 As shown, the pressure plate 30 is fixed to the back iron 10 by countersunk bolts 40. For details, please refer to... Figure 7 Each clamping arm 32 has a countersunk hole 322, and countersunk bolts 40 correspond one-to-one with the countersunk holes 322. The countersunk bolts 40 pass through the countersunk holes 322 and are threaded to the back iron 10. The head of the countersunk bolt 40 is recessed into the countersunk hole 322, with a small portion protruding from the surface of the clamping arm 32. The countersunk bolts 40 can fix the pressure plate 30 to the back iron 10, so that the second inclined pressure surface 321 of the clamping arm 32 presses against the first inclined pressure surface 21 of the magnet 20, thereby axially pre-tightening the magnet 20 and preventing it from falling off. This type of screw is also aesthetically pleasing and keeps the surface as flat as possible after installation. At the same time, the pressure plate 30 is also coated with adhesive to ensure a tight fit with the magnet 20 and the back iron 10, achieving a certain degree of sealing.

[0048] Optionally, such as Figure 1 As shown, the surface of the pressure plate 30 away from the back iron 10 is slightly lower than the outer surface of the magnet 20. This ensures that after the countersunk bolt 40 is tightened, the end face of the countersunk bolt 40 away from the back iron 10 is not higher than the outer surface of the magnet 20, thus ensuring that the surface of the rotor assembly remains as flat as possible.

[0049] This embodiment also provides an axial flux motor, which is a dual-stator single-rotor axial flux motor, including two stator assemblies and one rotor assembly, with the rotor assembly disposed between the two stator assemblies. The rotor assembly can be any of the aforementioned rotor assemblies, and all of these rotor assemblies have the aforementioned effects. The axial flux motor having these rotor assemblies also has the aforementioned effects, so they will not be described in detail here. It should be noted that the specific structure of the stator assembly is prior art and will not be described in detail here either.

[0050] It should be noted that the axial flux motor provided in this embodiment can be applied to electrical equipment. Optionally, the electrical equipment can be a vehicle, which can be a pure electric vehicle or a hybrid vehicle; this application does not impose any limitations. The axial flux motor can serve as a motor in a vehicle, used to output power to drive the wheels, for example, as a hub motor. The axial flux motor can also serve as a generator in a vehicle, generating electricity during vehicle operation to charge the vehicle's battery. Of course, in other optional embodiments, the electrical equipment may be other devices, which are not specifically limited here.

[0051] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A rotor assembly, characterized in that, The back iron (10) is provided with an inner cavity (14) on each side. Each inner cavity (14) is provided with a plurality of magnets (20). The plurality of magnets (20) on each side are evenly spaced along the circumference of the back iron (10). Each side of the back iron (10) is also provided with a pressure plate (30). The pressure plate (30) is pressed on the plurality of magnets (20) and connected to the back iron (10). Each inner wall of the inner cavity (14) is provided with a cooling channel (15). The cooling channel (15) is used to introduce a cooling medium to cool the back iron (10) and the plurality of magnets (20) on both sides.

2. The rotor assembly according to claim 1, characterized in that, The back iron (10) includes a disc body (11), a rotating shaft (12) and a retaining ring (13). The disc body (11) is arranged around the outer periphery of the rotating shaft (12). The retaining ring (13) is arranged around the outer periphery of the disc body (11) and together with the disc body (11) defines two inner cavities (14). The rotating shaft (12), the disc body (11) and the retaining ring (13) are integrally formed. The pressure plate (30) is sleeved on the outside of the rotating shaft (12).

3. The rotor assembly according to claim 2, characterized in that, The rotating shaft (12) is provided with an oil inlet hole (121) and an oil outlet hole (122). The cooling channel (15) includes an oil inlet straight groove (111), an oil outlet straight groove (112) and a plurality of annular grooves (113) provided on the disc body (11). The plurality of annular grooves (113) are arranged coaxially at intervals along the radial direction of the disc body (11). The oil inlet straight groove (111) and the oil outlet straight groove (112) are arranged at intervals along the circumference of the disc body (11) and both extend radially along the disc body (11). One end of the oil inlet straight groove (111) is connected to the oil inlet hole (121), and the other end of the oil inlet straight groove (111) is connected to the plurality of annular grooves (113). One end of the oil outlet straight groove (112) is connected to the oil outlet hole (122), and the other end of the oil outlet straight groove (112) is connected to the plurality of annular grooves (113).

4. The rotor assembly according to claim 3, characterized in that, The cooling channel (15) also includes a retaining ring groove (131), which is opened on the inner side wall of the retaining ring (13) and extends along the circumference of the retaining ring (13). The oil inlet straight groove (111) and the oil outlet straight groove (112) are both connected to the retaining ring groove (131).

5. The rotor assembly according to claim 1, characterized in that, The pressure plate (30) includes an annular portion (31) and a plurality of pressing arms (32). The plurality of pressing arms (32) are evenly connected to the outer periphery of the annular portion (31) along the circumference of the annular portion (31). The number of pressing arms (32) is the same as the number of magnets (20). There is a gap between two adjacent magnets (20). Each pressing arm (32) is accommodated in the corresponding gap and presses the sides of the magnets (20) on both sides.

6. The rotor assembly according to claim 5, characterized in that, The magnet (20) is fan-shaped. A first inclined pressure surface (21) is formed on the two straight edges of the magnet (20) away from the back iron (10). A second inclined pressure surface (321) is formed on the two straight edges of the clamping arm (32) corresponding to the magnet (20). The second inclined pressure surface (321) has the same inclination angle as the first inclined pressure surface (21) and they are in a corresponding pressing fit.

7. The rotor assembly according to claim 1, characterized in that, The pressure plate (30) is fixed to the back iron (10) by countersunk bolts (40).

8. The rotor assembly according to claim 7, characterized in that, The side surface of the pressure plate (30) away from the back iron (10) is lower than the outer surface of the magnet (20), and the end face of the countersunk bolt (40) away from the back iron (10) is not higher than the outer surface of the magnet (20).

9. The rotor assembly according to claim 1, characterized in that, The magnet (20) is attached to the bottom of the inner cavity (14) by adhesive.

10. An axial flux motor, characterized in that, It includes two stator assemblies and a rotor assembly as described in any one of claims 1-9, the rotor assembly being disposed between the two stator assemblies.

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