External rotor assembly and motor

Abstract

This utility model discloses an external rotor assembly, including: a rotor frame with a shaft hole at its center; and an output shaft, comprising a first assembly part, a toothed part, and a second assembly part, the first assembly part, the toothed part, and the second assembly part forming an integral stepped shaft, the first assembly part being interference-fitted with the shaft hole. An electric motor includes a stator and the aforementioned external rotor assembly. This utility model's external rotor assembly and motor integrate a toothed part and a bearing assembly part on the output shaft. The toothed part serves as a sun gear connected to a planetary gear reducer, better meeting the torque transmission requirements under conditions of high torque, dynamic stall, and frequent start-stop or forward / reverse rotation.

Description

Technical Field

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

[0002] In applications requiring high torque and low speed output, such as robot joints, servo motors paired with planetary gear reducers are a common solution. In the connection structure design between the motor and the planetary gear reducer, the motor output shaft and the sun shaft of the planetary gear reducer are two independently manufactured parts. Torque transmission is achieved through mechanical connections such as keys, couplings, or flanges. However, these mechanical connection structures generally suffer from problems such as structural complexity, high cost, cumbersome assembly processes, low efficiency, low rigidity, susceptibility to vibration and noise, and increased axial dimensions and weight.

[0003] Meanwhile, in the existing technology, the rotor shaft and rotor support are fixed only by interference fit. Under conditions of high torque, dynamic stall, and frequent start-stop or forward and reverse operation, rotational slippage inevitably occurs between the output shaft and the rotor support, resulting in torque transmission failure. Utility Model Content

[0004] The technical problem to be solved by this utility model is: in order to solve the technical problem of the complex connection structure between the output shaft of the motor and the sun shaft of the planetary gear reducer in the prior art, this utility model provides an external rotor assembly and a motor, which integrates a toothed part and a bearing assembly part on the output shaft. The toothed part serves as the sun gear and connects to the planetary gear reducer, simplifying the conventional connection structure, reducing costs, simplifying assembly steps, and reducing axial dimensions.

[0005] The technical solution adopted by this utility model to solve its technical problem is: an external rotor assembly, including: a rotor frame, the rotor frame having a shaft hole at its center; an output shaft, the output shaft including a first assembly part, a toothed part and a second assembly part, the first assembly part, the toothed part and the second assembly part forming an integral stepped shaft, the first assembly part being interference-fitted with the shaft hole.

[0006] The external rotor assembly of this utility model has an integrated stepped shaft for the output shaft. The output shaft serves as the output end of the rotor and can also be used as the sun gear of the planetary gear reducer. This simplifies the mechanical connection structure between the traditional motor and the reducer, not only improving the rigidity and efficiency of the transmission chain, but also effectively reducing the axial dimensions and assembly complexity.

[0007] Furthermore, in order to limit the assembly position of the output shaft, the shaft hole has an axial abutment portion, which cooperates with the bottom of the first assembly portion to limit the assembly position of the output shaft.

[0008] Furthermore, in order to ensure that the output shaft is securely installed, the bottom surface of the first assembly part has an assembly section that is tapered toward the axial abutment part. The assembly section is interference-fitted with the upper opening of the axial abutment part, and the inner diameter of the lower end of the axial abutment part is smaller than the inner diameter of the assembly section.

[0009] Furthermore, to prevent slippage between the output shaft and the rotor frame, the first assembly part and the shaft hole are assembled to form a keyway arranged along the axial direction, and a limit member is interference-fitted in the keyway.

[0010] Furthermore, the outer periphery of the first assembly part has at least one first groove, and the inner wall of the shaft hole has a second groove corresponding to the first groove. The first groove and the second groove are fitted together to form a keyway. This achieves an interference fit between the limiting member and the keyway.

[0011] Furthermore, the teeth protrude from the upper end face of the shaft hole, and the teeth are used as the sun gear of the planetary gear reducer. The second assembly part is a bearing assembly part.

[0012] Furthermore, the shaft hole has a mounting groove on the side axially away from the output shaft, and a signal magnet is mounted in the mounting groove. This completes the assembly of the signal magnet.

[0013] Furthermore, a support portion is provided on the outer side of the shaft hole, the support portion being located between the axial abutment portion and the assembly groove, and a bearing is mounted on the outer periphery of the shaft hole, the bearing contacting the support portion. This completes the bearing assembly.

[0014] Furthermore, the rotor frame is circumferentially distributed with isolation columns, and slots for mounting induction magnets are formed between the isolation columns. The outer surface of the isolation columns is interference-fitted with the inner surface of the rotor yoke. This completes the assembly of the induction magnets.

[0015] Furthermore, the rotor frame has an axial positioning surface on its end face, and the bottom surface of the rotor yoke is fitted onto the axial positioning surface. This achieves the positioning and assembly of the rotor frame and the rotor yoke.

[0016] Another technical solution adopted by this utility model to solve its technical problem is: an electric motor, including a stator and the above-mentioned outer rotor assembly.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] 1. The external rotor assembly and motor of this utility model have an interference fit between the output shaft and the rotor frame to achieve a rigid connection, ensuring that the torque of the motor can be transmitted to the planetary gear reducer without loss or delay. The output shaft serves as the output end of the external rotor assembly, and the teeth are integrated on the output shaft. The teeth can be directly connected to the planetary gear reducer as sun teeth, simplifying the assembly structure, simplifying the mechanical connection structure between the traditional motor and the reducer, reducing costs, simplifying assembly steps, and reducing axial dimensions.

[0019] 2. In this utility model, an additional limiting component is added between the rotor frame and the output shaft of the external rotor assembly and the motor as a redundant transmission element. When the interference connection between the rotor frame and the output shaft fails, the limiting component can bear the transmission of working torque, ensuring that the function of the power transmission system will not be interrupted. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is an exploded view of the outer rotor assembly of this utility model;

[0022] Figure 2 This is a cross-sectional view of the outer rotor assembly;

[0023] Figure 3 This is a three-dimensional structural diagram of the rotor frame;

[0024] Figure 4 This is a schematic diagram of the output shaft.

[0025] Figure 5 This is a three-dimensional structural diagram of the external rotor assembly;

[0026] Figure 6 This is a partial structural schematic diagram of the rotor frame of the external rotor assembly in Embodiment 2;

[0027] Figure 7 This is a schematic diagram of the output shaft of the external rotor assembly in Embodiment 2;

[0028] Figure 8 This is a schematic diagram of the assembly structure of the output shaft, rotor frame, and limiting component in Embodiment 2.

[0029] In the figure: 1. Rotor frame, 11. Shaft hole, 111. Axial abutment part, 112. Support part, 113. Assembly groove, 114. Second groove body, 12. Isolation column, 13. Axial positioning surface, 14. Groove body, 2. Output shaft, 21. First assembly part, 211. Assembly section, 212. First groove body, 22. Tooth part, 23. Second assembly part, 3. Rotor yoke, 4. Induction magnet, 5. Bearing, 6. Signal magnet, 7. Limiting component. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0031] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

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

[0033] like Figure 1 , Figure 2 and Figure 5 As shown, an external rotor assembly includes: a rotor frame 1, an output shaft 2, a rotor yoke 3, an induction magnet 4, a bearing 5, and a signal magnet 6.

[0034] Specifically, the rotor frame 1 has a shaft hole 11 at its center. For example... Figure 4 As shown, the output shaft 2 includes a first assembly part 21, a gear part 22, and a second assembly part 23. The first assembly part 21, the gear part 22, and the second assembly part 23 form an integral stepped shaft. The first assembly part 21 is interference-fitted with the shaft hole 11. The integral output shaft 2 can be divided into three key parts according to its functional area: the rotor support assembly part (first assembly part 21), the gear part 22, and the bearing assembly part (second assembly part 23). The rotor support assembly part needs to be machined by turning or grinding to ensure a high coaxiality connection with the rotor support 1.

[0035] Preferably, the tooth 22 protrudes from the upper end face of the shaft hole 11, and the tooth 22 serves as the sun gear of the planetary gear reducer. The dimensions of the tooth 22 are the same as the sun gear tooth profile of the planetary transmission mechanism. The tooth profile is pre-designed and pressed into the powder metallurgy blank according to the relevant parameters of the planetary reducer gear system to ensure meshing accuracy with the planetary gear system, while also better reducing noise.

[0036] Preferably, the second assembly part 23 is a bearing assembly part. The bearing assembly part is used to support and position the rotor shaft system.

[0037] Output shaft 2 is manufactured using powder metallurgy, where a mixture of metal powder and binder is injected into a precision mold cavity for one-piece metal injection molding. This mold cavity structure already incorporates all the structural features of the rotor shaft, eliminating the need for subsequent machining. This highly integrated design simplifies the mechanical connection between the traditional motor and gearbox, not only improving the rigidity and efficiency of the transmission chain but also effectively reducing axial dimensions and assembly complexity.

[0038] Specifically, such as Figure 3 As shown, the shaft hole 11 has an axial abutment portion 111, which engages with the bottom of the first assembly portion 21 to limit the assembly position of the output shaft 2.

[0039] Preferably, the bottom surface of the first assembly part 21 has an assembly section 211 that is tapered toward the axial abutment part 111. The assembly section 211 is interference-fitted with the upper opening of the axial abutment part 111, and the inner diameter of the lower end of the axial abutment part 111 is smaller than the inner diameter of the assembly section 211.

[0040] The function of the axial abutment portion 111 is to axially limit the output shaft 2, restricting its position within the shaft hole 11. Simultaneously, the interference fit between the assembly section 211 and the axial abutment portion 111 ensures torque transmission.

[0041] The processing technology of the output shaft 2 gives it high torsional strength and wear resistance. The output shaft 2 is slowly pressed into the shaft hole 11 of the rotor frame 1 by a servo press, and the pressing length is strictly controlled. The output shaft 2 and the rotor frame 1 are rigidly connected by interference fit, which ensures that the torque of the motor can be transmitted to the planetary gear reducer without loss or delay.

[0042] Specifically, the shaft hole 11 has a mounting groove 113 on the side away from the output shaft 2 along the axial direction, and a signal magnet 6 is mounted in the mounting groove 113.

[0043] Specifically, a support portion 112 is provided on the outer side of the shaft hole 11. The support portion 112 is located between the axial abutment portion 111 and the mounting groove 113, and the bearing 5 is mounted on the outer periphery of the shaft hole 11 and contacts the support portion 112.

[0044] Specifically, the rotor frame 1 is circumferentially distributed with isolation columns 12, and slots 14 for installing induction magnets 4 are formed between the isolation columns 12. The outer side of the isolation column 12 is interference-fitted with the inner side of the rotor yoke 3.

[0045] Specifically, the rotor frame 1 has an axial positioning surface 13 on its end face, and the bottom surface of the rotor yoke 3 is fitted onto the axial positioning surface 13, thereby enabling the assembly of the rotor yoke 3. To enhance the connection strength between the rotor frame 1 and the rotor yoke 3, a mechanical structure retaining adhesive can be applied to the inner wall surface of the rotor yoke 3.

[0046] The rotor frame 1 is made of cast metal, such as magnesium alloy or aluminum alloy, which has high strength and light weight. The rotor frame 1 must be made of non-magnetic material to constrain the magnetic flux path, prevent leakage magnetic flux in the rotor yoke 3, and improve magnetic field utilization. The rotor yoke 3 must be made of magnetic material and is a key part of the motor's main magnetic circuit. The induction magnet 4 is made of rare earth neodymium iron boron material, which is sintered and then directionally magnetized to obtain extremely high magnetic energy product and coercivity. The induction magnet 4 is embedded in the distribution slot of the rotor frame 1, and its outer surface is fixed to the inner wall of the rotor yoke 3 by adhesive bonding. In this way, the induction magnets 4 with different N and S polarities can be distributed at intervals on the inner wall of the rotor yoke 3, generating a regular magnetic flux distribution inside the rotor yoke 3. This is the basis for the motor to generate stable and efficient electromagnetic torque.

[0047] Example 2, based on Example 1, such as Figures 6 to 8 As shown, the first assembly part 21 and the shaft hole 11 are assembled to form a keyway arranged axially, and a limiting member 7 is interference-fitted within the keyway. Normally, the interference fit between the rotor frame 1 and the output shaft 2 can ensure sufficient torque transmission. However, under stall conditions, dynamic impacts, and high / low temperature conditions, rotational slippage inevitably occurs between the output shaft 2 and the rotor frame 1, leading to torque transmission failure. Therefore, adding a limiting member 7 between the first assembly part 21 and the shaft hole 11 can further improve the torque transmission capability of the rotor assembly under extreme conditions. As a redundant transmission element, the limiting member 7 can independently bear the output of working torque when the motor is under extreme conditions causing the interference fit between the rotor frame 1 and the output shaft 2 to fail, ensuring that the power transmission system function is not interrupted.

[0048] Preferably, the outer periphery of the first assembly part 21 has at least one first groove 212, and the inner wall of the shaft hole 11 has a second groove 114 corresponding to the first groove 212. The first groove 212 and the second groove 114 cooperate to form a keyway.

[0049] In this embodiment, both the first groove 212 and the second groove 114 are arc-shaped keyways, which can be directly formed by a mold without subsequent processing. During assembly, the cylindrical limiting member 7 is placed close to the arc-shaped keyway of the rotor frame 1, and the arc-shaped keyway of the output shaft 2 is aligned with the limiting member 7. Guided by the limiting member 7, the output shaft 2 can be smoothly pressed into the shaft hole 11. This structure and assembly method can not only ensure the assembly accuracy of the output shaft 2 being pressed into the rotor frame 1, but also effectively improve the torque transmission capability under stall and dynamic impact conditions.

[0050] Of course, the structure of the keyway and the limiting component is not limited to cylindrical; it can be rectangular, square, rhomboid, or other structures that can achieve torque transmission.

[0051] In summary, the external rotor assembly and motor of this utility model integrate a toothed section and a bearing assembly on the output shaft. The toothed section serves as the sun gear and connects to the planetary gear reducer, which can better meet the torque transmission requirements under conditions of high torque, dynamic stall, and frequent start-stop or forward and reverse rotation.

[0052] The above description is based on the preferred embodiments of this utility model. Through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. An outer rotor assembly characterized by, The application relates to a rotor assembly. The rotor assembly comprises: a rotor frame (1) with a shaft hole (11) in the center; 2. The outer rotor assembly of claim 1, wherein an output shaft (2) comprising a first assembly part (21), a tooth part (22) and a second assembly part (23), which are integrated into a stepped shaft, and the first assembly part (21) is in interference fit with the shaft hole (11).

3. The outer rotor assembly of claim 2, wherein, The shaft hole (11) has an axial abutment part (111) inside, which cooperates with the bottom of the first assembly part (21) to limit the assembly position of the output shaft (2).

4. The outer rotor assembly of claim 3, wherein, The bottom surface of the first assembly part (21) has an assembly section (211) in the shape of a reduced diameter towards the axial abutment part (111), which is in interference fit with the upper end opening of the axial abutment part (111), and the inner diameter of the lower end of the axial abutment part (111) is smaller than that of the assembly section (211).

5. The outer rotor assembly of claim 4, wherein, The first assembly part (21) and the shaft hole (11) are assembled to form a key groove arranged along the axial direction, and the key groove is in interference connection with a limiting piece (7).

6. An outer rotor assembly according to any one of claims 1 to 5, wherein The outer periphery of the first assembly part (21) has at least one first groove (212), and the inner wall of the shaft hole (11) has a second groove (114) corresponding to the first groove (212), and the first groove (212) and the second groove (114) are correspondingly matched to form the key groove.

7. The outer rotor assembly of claim 2, wherein The tooth part (22) is exposed on the upper end surface of the shaft hole (11), and the tooth part (22) is used as a sun gear of a planetary gear reducer, and the second assembly part (23) is a bearing assembly part.

8. The outer rotor assembly of claim 7, wherein, The shaft hole (11) has an assembly groove (113) on the side away from the output shaft (2) along the axial direction, and a signal magnetic steel (6) is assembled in the assembly groove (113).

9. The outer rotor assembly of claim 1, wherein, The outer side of the shaft hole (11) is provided with a support part (112) between the axial abutment part (111) and the assembly groove (113), and a bearing (5) is assembled on the outer periphery of the shaft hole (11) and is in contact with the support part (112).

10. The outer rotor assembly of claim 9, wherein, The rotor frame (1) is uniformly distributed with isolation columns (12), and grooves (14) for mounting an induction magnetic steel (4) are formed between the isolation columns (12), and the outer side surface of the isolation column (12) is in interference fit with the inner side surface of a rotor magnetic yoke (3).

11. An electric machine characterized by The rotor frame (1) has an axial positioning surface (13) on the end surface, and the bottom surface of the rotor magnetic yoke (3) is matched and arranged on the axial positioning surface (13). The application further relates to a motor comprising a stator and the outer rotor assembly as claimed in any one of claims 1-10.

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