Outer rotor motor

Abstract

An external rotor motor includes a shaft, an external rotor assembly, and an inner stator assembly. The inner stator assembly includes a stator bracket and an inner stator core fixed to the bracket. The stator bracket has a base located on one axial side of the inner stator core and a support portion extending axially from the base. The support portion is sleeved on the outer periphery of the shaft, and the inner stator core is fixed to the outer periphery of the support portion. The stator bracket has a steel sleeve integrally formed on the support portion, and the inner wall of the inner stator core abuts against the outer surface of the steel sleeve. The steel sleeve adopts a double-sided boss structure. Integral injection molding of the stator bracket and the steel sleeve does not increase the complexity of the process; at the same time, the double-sided boss structure can enhance the structural strength and fit stability between the two, and ensure dimensional consistency; the interference fit between the steel sleeve and the inner stator core does not generate cutting waste, and while ensuring a stable bonding force between the two, it can effectively reduce the impact on other components during motor production.

Description

[Technical Field]

[0001] This invention relates to the field of external rotor motor technology, and in particular to an external rotor motor with an improved stator support. [Background Technology]

[0002] Traditional external rotor motors mostly use a bracket inserted into the stator core. As a structural connector between the motor and the entire machine, the bracket must ensure a certain strength, and it is generally made of aluminum alloy. The aluminum alloy bracket and the steel stator core are fitted with an interference fit to ensure that the bonding force between them meets the motor's operating requirements. However, due to the differences in the material properties of steel and aluminum, the interference fit can cause the aluminum to be cut during pressing, resulting in aluminum shavings, which significantly affects the bonding strength. At the same time, the aluminum shavings generated during the production process can affect other components in the motor, causing friction between the stator and rotor, abnormal noise, failure, and even endangering personal safety.

[0003] Therefore, it is indeed necessary to provide an improved external rotor motor to overcome the shortcomings of the prior art. [Summary of the Invention]

[0004] In view of the shortcomings of the prior art, the problem to be solved by the present invention is to improve the bonding force between the motor bracket and the stator core.

[0005] The technical solution adopted by the present invention to solve the problem of the prior art is as follows: an external rotor motor, including an axially extending shaft, an external rotor assembly fixed on the shaft, and an inner stator assembly located between the shaft and the external rotor assembly. The inner stator assembly includes a stator bracket sleeved on the outer periphery of the shaft and an inner stator core fixed on the stator bracket. The stator bracket has a base located on one axial side of the inner stator core and a support portion extending axially from the base. The support portion is sleeved on the outer periphery of the shaft, and the inner stator core is fixed on the outer periphery of the support portion. The stator bracket has a steel sleeve integrally formed on the support portion, and the inner wall of the inner stator core is fixed to the outer surface of the steel sleeve.

[0006] A further improvement is that the hardness of the support portion is less than the hardness of the steel kit, the outer periphery of the steel kit is at least partially exposed outside the support portion, and the outer diameter of the steel kit is not less than the outer diameter of the support portion.

[0007] A further improvement is as follows: the steel kit is provided with a sleeve portion and bosses located at both axial ends of the sleeve portion; the stator bracket is provided with stop portions located at both axial ends of the sleeve portion; when the steel kit is integrally formed into the support portion, the stop portions are embedded in the support portion.

[0008] A further improvement is as follows: the inner stator assembly includes an inner stator core sleeved on the outer periphery of the support portion, the inner diameter of the inner stator core is not greater than the outer diameter of the steel kit, and the inner peripheral surface of the inner stator core is fitted onto the outer peripheral surface of the steel kit.

[0009] A further improvement is that the material of the inner stator core is the same as that of the steel kit, and both are made of steel.

[0010] A further improvement is as follows: the inner stator core is provided with teeth evenly distributed along the outer periphery, and the inner stator assembly includes a winding wound around the outer periphery of the teeth and a stator encapsulation covering the outside of the winding, wherein the stator encapsulation fixes the winding to the inner stator core.

[0011] A further improvement is as follows: the outer rotor assembly includes a rotor housing fixed on the rotating shaft, a magnet seat located inside the rotor housing, and several magnets installed on the magnet seat. The rotor housing covers the outer periphery of the inner stator core.

[0012] A further improvement is as follows: the rotor housing is provided with an annular wall sleeved on the outer periphery of the inner stator core and an end wall located on one axial side of the annular wall, the end wall being fixed on the rotating shaft, and the magnet seat being provided on the inner wall of the annular wall.

[0013] A further improvement is as follows: the rotating shaft is provided with a first bearing and a second bearing located at both ends of the axial direction, and the rotating shaft is supported in the stator bracket by the first bearing.

[0014] A further improvement is as follows: the external rotor motor includes a motor housing that encloses the inner stator assembly and the external rotor assembly, the stator bracket is fixedly connected to one axial end of the motor housing, and the rotating shaft is supported on the other axial end of the motor housing by the second bearing.

[0015] Compared with existing technologies, the present invention has the following advantages: The stator support is provided with a steel component integrally formed on the support portion, and the integral injection molding does not increase the complexity of the process; moreover, the material properties of the steel component and the inner stator core are similar, and the interference fit between the two will not lead to the generation of cutting waste. While ensuring a stable bonding force between the two, it can effectively reduce the impact on other components during motor production and operation. At the same time, the double-sided boss structure of the steel component can greatly enhance the structural strength and fit stability between the two, and ensure dimensional consistency. The inner wall of the inner stator core abuts against the outer surface of the steel component. Matching the outer surface of the steel component with the inner wall of the inner stator core can reduce the precision machining process, making the manufacturing process simpler. [Image Description]

[0016] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings:

[0017] Figure 1 This is a three-dimensional schematic diagram of an external rotor motor according to a preferred embodiment of the present invention;

[0018] Figure 2 yes Figure 1 A three-dimensional schematic diagram of the external rotor motor from another angle;

[0019] Figure 3 yes Figure 1 A cross-sectional view of the external rotor motor shown;

[0020] Figure 4 yes Figure 1 The exploded view of the external rotor motor shown;

[0021] Figure 5 yes Figure 4 A three-dimensional schematic diagram of the stator support in an external rotor motor is shown.

[0022] Figure 6 yes Figure 4 A three-dimensional schematic diagram of the steel components in the external rotor motor is shown.

[0023] Meaning of the reference numerals in the diagram:

[0024] 100. External rotor motor; 10. Motor housing; 11. Air inlet; 12. Bearing end cover; 20. Rotating shaft; 21. First bearing; 22. Second bearing; 23. Snap ring; 30. Inner stator assembly; 31. Stator bracket; 311. Base; 312. Support; 313. Steel fitting; 3131. Boss; 3132. Sleeve; 314. Stop; 315. Screw; 32. Inner stator core; 321. Gear; 33. Stator sealing material; 34. Winding; 40. External rotor assembly; 41. Rotor housing; 411. Annular wall; 412. End wall; 42. Magnet seat; 43. Magnet; 50. Fan. [Detailed Implementation]

[0025] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as "upper," "lower," "front," and "rear" that indicate orientation or positional relationship are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device / 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 the invention.

[0026] Please see Figures 1 to 6The diagram illustrates a preferred embodiment of an external rotor motor 100 according to the present invention. This motor is typically used to connect to a power tool and features convenient operation and maintenance, simple and feasible assembly, and environmental friendliness and economy. The external rotor motor 100 includes an axially extending shaft 20, an external rotor assembly 40 connected to the shaft 20, an inner stator assembly 30 located between the shaft 20 and the external rotor assembly 40, a fan 50 fixed to the shaft 20, and a motor housing 10 enclosing the inner stator assembly 30 and the external rotor assembly 40. The shaft 20 rotates relative to the inner stator assembly 30 as the external rotor assembly 40 rotates, and the fan 50 rotates as the shaft 20 rotates.

[0027] Please see Figure 1 and Figure 2 As shown, the motor housing 10 has several air inlets 11 near the fan 50. These air inlets 11 are evenly distributed below the motor housing 10 and surround the fan 50. The air inlets 11 provide cooling air to the external rotor motor 100. The cooling air enters the fan blades of the fan 50 through the air inlets 11, and after rotational motion, is blown onto the external rotor assembly 40 to cool the external rotor motor 100. In this embodiment, there are nine air inlets in a square shape, ensuring sufficient airflow for cooling while maintaining an aesthetically pleasing appearance. Preferably, one or more inlets can be selected, and the shape can be any shape or a combination of different shapes.

[0028] Please see Figures 3 to 6 As shown, the inner stator assembly 30 includes a stator bracket 31 sleeved on the outer periphery of the rotating shaft 20, an inner stator core 32 fixed on the stator bracket 31, a stator encapsulation 33 for placing the inner stator core 32, and a winding 34 wound around the outer periphery of the inner stator core 32.

[0029] The stator support 31 includes a base 311 located on one axial side of the inner stator core 32, a support portion 312 extending axially from the base 311, a steel sleeve 313 integrally formed on the support portion 312, and stop portions 314 located at both axial ends of the steel sleeve 313. At least a portion of the outer periphery of the steel sleeve 313 protrudes from the outside of the support portion 312, and the outer diameter of the steel sleeve 313 is not less than the outer diameter of the support portion 312. This design allows for an interference fit when the two parts are engaged, without increasing structural complexity, preventing the inner stator core 32 from detaching from the steel sleeve 313, and improving load-bearing capacity and the transmission of large torques. The stator support 31 also includes a plurality of screws 315 for connecting the stator support 31 to the motor housing 10.

[0030] The steel component 313 is injection molded from steel, and its material is the same as that of the inner stator core 32. During the injection molding of the stator support 31, the steel component 313 is integrally molded within it. In this embodiment, the two components fit tightly together; preferably, other fitting methods, such as clearance fit, can be used. The stop portion 314 is embedded within the support portion 312. The stop portion 314 can be integrally molded with the stator support 31, or preferably, it can be fixed to both ends of the steel component 313 after the stator support 31 is injection molded. The material of the stop portion 314 can be different from that of the stator support 31. In this embodiment, the stator support 31 is integrally injection molded from aluminum; preferably, other materials can be used. This manufacturing method does not increase the complexity of the process.

[0031] The steel assembly 313 includes a sleeve portion 3131 and bosses 3132 located at both axial ends of the sleeve portion 3131. The inner circumferential surface of the inner stator core 32 is fitted onto the outer circumferential surface of the sleeve portion 3131, and the bosses 3132 abut against the stop portion 314. The inner diameter of the inner stator core 32 is not greater than the outer diameter of the steel assembly 313. The material of the inner stator core 32 is the same as that of the steel assembly 313, so their material properties are similar. During installation, the interference fit between the two will not cause cutting waste, thus avoiding affecting the normal operation of the motor. The bosses 3132 can greatly enhance the structural strength and fit stability between the steel assembly 313 and the support portion 312, and ensure dimensional consistency.

[0032] In traditional external rotor motor assembly methods, the outer circumferential surface of the stator bracket 31 is directly fitted with the inner circumferential surface of the inner stator core 32. This not only generates aluminum shavings during installation, but also creates static friction between the inner stator core 32 and the stator bracket 31 during high-speed motor operation. When the external force exceeds the maximum static friction, there is a tendency for relative sliding between the two, causing the inner stator core 32 to cut into the stator bracket 31. The resulting aluminum shavings can affect the running motor and other components, causing friction between the stator and rotor, abnormal noise, failure, and even endangering personal safety. In this embodiment, the identical materials of both components result in similar material properties, and the interference fit between the steel components ensures a stable bonding force, greatly reducing or even eliminating the possibility of relative sliding, thus preventing shavings and ensuring the safety of the motor during operation.

[0033] The inner stator core 32 has teeth 321 evenly distributed along its outer periphery. The winding 34 is wound around the outer periphery of the teeth 321. The stator molding compound 33 covers the outside of the winding 34, and the inner stator core 32 is installed in the stator molding compound 33. In this embodiment, the number of windings 34 is 12; preferably, the number can be one or more.

[0034] The outer rotor assembly 40 includes a rotor housing 41 fixed to the rotating shaft 20, a magnet base 42 located inside the rotor housing 41, and several magnets 43 mounted on the magnet base 42. The rotor housing 41 has an annular wall 411 sleeved around the outer periphery of the inner stator core 32 and an end wall 412 located on one axial side of the annular wall 411. The end wall 412 is fixed to the rotating shaft 20. The magnets 43 are uniformly attached to the inner wall of the annular wall 411 circumferentially. The fan 50 is located between the end wall 412 and the magnet base 42. The rotor housing 41 covers the outer periphery of the inner stator core 32. In this embodiment, 10 magnets 43 are selected, and they are square in shape; preferably, one or more magnets can be selected, and their shape can be arbitrary.

[0035] The rotating shaft 20 includes a first bearing 21 and a second bearing 22 located at both axial ends, and a retaining ring 23 located outside the first bearing 21. The retaining ring 23 axially limits the first bearing 21. The rotating shaft 20 is supported within the stator bracket 31 by the first bearing 21 and supported at the other axial end of the motor housing 10 by the second bearing 22. The bottom of the motor housing 10 includes a bearing end cap 12, which is used to enclose the second bearing 22.

[0036] In this embodiment, the stator bracket 31 is provided with a steel fitting 313 integrally formed on the support portion 312. This integral injection molding process does not increase the complexity of the manufacturing process. Simultaneously, the double-sided boss 3131 structure of the steel fitting 313 greatly enhances the structural strength and fit stability between the two components, while ensuring dimensional consistency. The inner wall of the inner stator core 32 abuts against the outer surface of the steel fitting 313. Matching the outer surface of the steel fitting 313 with the inner wall of the inner stator core 32 reduces the need for precision machining, simplifying the manufacturing process. Since the steel fitting 313 and the inner stator core 32 have similar material properties, the interference fit between them does not result in the generation of cutting waste. While ensuring a stable bonding force between the two components, this effectively reduces the impact on other parts during motor production and operation.

[0037] This invention is not limited to the specific embodiments described above. Those skilled in the art will readily understand that many alternative solutions for the external rotor motor of this invention exist without departing from the principles and scope of the invention. The scope of protection of this invention is defined by the claims.

Claims

1. An external rotor motor, comprising an axially extending shaft, an external rotor assembly fixed to the shaft, and an inner stator assembly located between the shaft and the external rotor assembly, the inner stator assembly comprising a stator bracket sleeved on the outer periphery of the shaft and an inner stator core fixed to the stator bracket, the stator bracket having a base located on one axial side of the inner stator core and a support portion extending axially from the base, the support portion sleeved on the outer periphery of the shaft, and the inner stator core fixed to the outer periphery of the support portion; characterized in that: The stator support is provided with a steel kit integrally formed on the support portion. The inner wall of the inner stator core is fixed to the outer surface of the steel kit. The axial dimension of the steel kit is smaller than the axial dimension of the inner stator core. The steel kit is provided with a sleeve portion and bosses located at both axial ends of the sleeve portion. The stator support is provided with stop portions located at both axial ends of the sleeve portion. The bosses are embedded in the stop portions.

2. The external rotor motor according to claim 1, characterized in that: The hardness of the support portion is less than the hardness of the steel kit, the outer periphery of the steel kit is at least partially exposed outside the support portion, and the outer diameter of the steel kit is not less than the outer diameter of the support portion.

3. The external rotor motor according to claim 1, characterized in that: The inner stator assembly includes an inner stator core sleeved on the outer periphery of the support portion. The inner diameter of the inner stator core is not greater than the outer diameter of the steel kit, and the inner circumferential surface of the inner stator core is fitted onto the outer circumferential surface of the steel kit.

4. The external rotor motor according to claim 3, characterized in that: The inner stator core is made of the same material as the steel kit; both are made of steel.

5. The external rotor motor according to claim 3, characterized in that: The inner stator core is provided with teeth evenly distributed along its outer periphery. The inner stator assembly includes a winding wound around the outer periphery of the teeth and a stator encapsulation covering the outside of the winding. The stator encapsulation fixes the winding to the inner stator core.

6. The external rotor motor according to claim 1, characterized in that: The outer rotor assembly includes a rotor housing fixed to the rotating shaft, a magnet base located inside the rotor housing, and several magnets mounted on the magnet base. The rotor housing covers the outer periphery of the inner stator core.

7. The external rotor motor according to claim 6, characterized in that: The rotor housing has an annular wall sleeved on the outer periphery of the inner stator core and an end wall located on one axial side of the annular wall. The end wall is fixed on the rotating shaft, and the magnet seat is located on the inner wall of the annular wall.

8. The external rotor motor according to claim 1, characterized in that: The rotating shaft is provided with a first bearing and a second bearing at both ends of the axial direction, and the rotating shaft is supported in the stator bracket by the first bearing.

9. The external rotor motor according to claim 8, characterized in that: The external rotor motor includes a motor housing that encloses the inner stator assembly and the external rotor assembly. The stator bracket is fixedly connected to one axial end of the motor housing, and the rotating shaft is supported at the other axial end of the motor housing by the second bearing.

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