An outer rotor electric motor

Abstract

The application provides an outer rotor motor, which comprises a rotor assembly, a rotor shell, a stator assembly and a bearing. The end of the rotor assembly is connected with the axial end of the rotor shell, so that the rotor assembly can rotate integrally with the rotor shell. The bearing is located at the inner periphery of the axial end of the rotor shell to support the rotor shell. The axial other end of the rotor shell extends to the radial outer periphery of at least part of the structure of the stator assembly. The rotor shell can be driven to rotate by the stator assembly, so as to drive the rotor assembly to rotate integrally. According to the application, the arrangement of one bearing can be effectively reduced. Compared with the conventional outer rotor motor structure which needs to be provided with two bearings, or the scheme of one long bearing, the cost of one small but high-priced bearing is effectively saved, so that the cost of the outer rotor motor is reduced, and the noise and vibration are also reduced.

Description

An external rotor motor Technical Field

[0001] This invention relates to the field of motor technology, and specifically to an external rotor motor. Background Technology

[0002] In the household motor industry, the current pressures of energy efficiency upgrades and cost, as well as customers' increasing noise requirements, necessitate the development of low-cost DC motors to address these issues. Only such motor products have an advantage and competitiveness. Existing small DC external rotor motors on the market have relatively high efficiency and meet energy efficiency requirements, but they require two bearings: one ordinary bearing and one bearing with a smaller diameter. The cost of this small bearing is very high, and the sleeve shape of traditional small external rotor DC motors is somewhat complex, which also leads to high costs.

[0003] Because existing external rotor motors require two bearings for support, resulting in higher costs, this invention researches and designs an external rotor motor. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the external rotor motor in the prior art requires two bearings for support, resulting in high cost, and thus provide an external rotor motor.

[0005] To address the above problems, the present invention provides an external rotor motor, comprising:

[0006] The rotor assembly comprises a rotor housing, a stator assembly, and a bearing. One end of the rotor assembly can be connected to one axial end of the rotor housing so that the rotor assembly can rotate integrally with the rotor housing. The bearing is located on the inner circumference of one axial end of the rotor housing to support the rotor housing. The other axial end of the rotor housing extends to the radial outer circumference of at least a portion of the structure of the stator assembly. The rotor housing can be driven to rotate by the stator assembly to drive the rotor assembly to rotate integrally.

[0007] In some embodiments, the rotor assembly includes a rotor shaft, a first annular portion, and a first cylindrical body. The radial outer periphery of the rotor shaft is connected to the radial inner periphery of the first annular portion. The first cylindrical body is connected to the radial outer periphery of the first annular portion and extends axially along the rotor shaft. The rotor housing includes a second annular portion, a second cylindrical body, and a third cylindrical body. The second cylindrical body is connected to the radial inner periphery of the second annular portion. The third cylindrical body is connected to the radial outer periphery of the second annular portion and extends axially to the radial outer side of the stator assembly. The first cylindrical body and the second cylindrical body are sleeved together and can rotate integrally. The bearing is located on the radial inner periphery of the second cylindrical body to support the rotor housing. The stator assembly can drive the third cylindrical body to rotate, thereby driving the rotor shaft to rotate.

[0008] In some embodiments, the first cylinder is sleeved on the outer periphery of the second cylinder, and the two are fixed together by interference fit, threaded fastening or snap fastening, and the outer ring of the bearing rotates integrally with the second cylinder; the first annular part is a circular ring structure, the first cylinder is a cylindrical structure without bottoms at both ends, the second annular part is a circular ring structure, and both the second cylinder and the third cylinder are cylindrical structures without bottoms at both ends.

[0009] In some embodiments, the stator assembly includes a stator core, a stator coil, and a stator sleeve. The stator sleeve passes through the radial inner circumference of the stator core to fix the stator core. A stator shaft is also fixedly connected to one end of the stator sleeve facing the rotor assembly. The stator shaft passes through the inner circumference of the bearing to support the bearing.

[0010] In some embodiments, the rotor housing further includes a fourth cylinder and a third annular portion. One axial end of the fourth cylinder is connected to the axial end of the second cylinder, and the other axial end of the fourth cylinder extends axially away from the second cylinder. The radially outer end of the third annular portion is connected to the radially inner circumference of the fourth cylinder, and the third annular portion extends radially inward. The third annular portion can axially limit one axial end of the bearing, and the first annular portion of the rotor assembly can axially limit the other axial end of the bearing. This allows the bearing to be disposed within the space enclosed by the first annular portion, the second cylinder, the fourth cylinder, the third annular portion, and the stator shaft, forming a bearing chamber.

[0011] In some embodiments, the second cylinder is connected to one axial end of the second annular portion, and the fourth cylinder is connected to the other axial end of the second annular portion, such that the second annular portion is located between the second cylinder and the fourth cylinder, and the inner and outer diameters of the second cylinder and the fourth cylinder are the same, and the two can be manufactured as one piece; the radial outer end of the third annular portion is connected to the radial inner end at the free end of the fourth cylinder.

[0012] In some embodiments, a magnetic structure is provided on at least one of the second annular portion and the third cylindrical body of the rotor housing, the magnetic structure being disposed on the side of the second annular portion and the third cylindrical body facing the stator core.

[0013] In some embodiments, a control plate is also provided on the stator sleeve. The control plate has an annular plate structure and is sleeved on the stator sleeve.

[0014] In some embodiments, at least one of the outer periphery of the stator sleeve and the inner periphery of the stator core is provided with a protruding ridge, and the other is provided with at least one groove, wherein the protruding ridge (35) and the groove are inserted into each other in a one-to-one correspondence.

[0015] In some embodiments, the external rotor motor is a DC motor.

[0016] The external rotor motor provided by this invention has the following beneficial effects:

[0017] 1. This invention, through the arrangement of the rotor housing, enables one axial end to be integrated with the rotor assembly, allowing both to rotate as a single unit. The other end of the rotor housing extends to the radial outer periphery of the stator assembly, allowing the stator assembly to drive the rotor housing to rotate. The bearing is located at the junction of the rotor housing and the rotor assembly, simultaneously supporting both the rotor assembly and the rotor housing. Therefore, this application effectively eliminates the need for the rotor shaft to pass through the stator, allowing for effective support of both the rotor assembly and the rotor housing with a single bearing. The stator side does not require a supporting bearing, thus effectively reducing the need for a bearing. Compared to existing conventional external rotor motor structures that require two bearings or a long bearing, this invention effectively saves the cost of a small but expensive bearing, thereby reducing the cost of the external rotor motor and also reducing noise and vibration.

[0018] 2. The outer rotor of this invention adopts an integrated design, consisting of a magnetic strip (any magnetically conductive material is acceptable), a rotor housing, a bearing chamber, and a rotor shaft. During the manufacturing of the outer rotor, the bearing is embedded inside the bearing chamber of the housing. After the rotor shaft is tightly pressed against the outer end face of the bearing chamber, the entire assembly is formed as one piece. This integrated rotor design reduces motor vibration and noise, and reduces labor hours. In this invention, the rotor shaft and stator are located on opposite sides. One end of the rotor shaft is on the rotor bearing chamber, and the other end is directly connected to the fan blade. With the same motor installation dimensions, the rotor shaft length can be significantly reduced, lowering fluctuations during motor operation. Attached Figure Description

[0019] Figure 1 is a cross-sectional view of the assembly structure of the external rotor motor of the present invention;

[0020] Figure 2a is a perspective view of the assembly structure of the external rotor motor of the present invention;

[0021] Figure 2b is a two-dimensional view of the assembly structure of the external rotor motor of the present invention;

[0022] Figure 3 is an exploded structural diagram of the external rotor motor of the present invention;

[0023] Figure 4 is an assembly structure diagram of the integrated rotor assembly in the external rotor motor of the present invention;

[0024] Figure 5 is an exploded view of the integrated rotor assembly in the external rotor motor of the present invention;

[0025] Figure 5a is a view of the rotor housing from another direction in Figure 5;

[0026] Figure 6a is a schematic diagram of the stator sleeve in the external rotor motor of the present invention.

[0027] Figure 6b is a schematic diagram of the stator sleeve in the external rotor motor of the present invention.

[0028] Figure 7 is a schematic diagram of the stator core in the external rotor motor of the present invention.

[0029] The reference numerals in the attached figures are as follows:

[0030] 1. Rotor assembly; 11. Rotor shaft; 12. First annular section; 13. First cylinder; 2. Rotor housing; 21. Second annular section; 22. Second cylinder; 23. Third cylinder; 24. Fourth cylinder; 25. Third annular section; 3. Stator assembly; 31. Stator core; 32. Stator coil; 33. Stator sleeve; 34. Stator shaft; 35. Raised ridge; 36. Groove; 37. Mounting bracket; 38. Inclined groove; 4. Bearing; 40. Bearing chamber; 5. Magnetic structure; 6. Control board. Detailed Implementation

[0031] As shown in Figures 1-7, the present invention provides an external rotor motor, which includes:

[0032] The rotor assembly 1, rotor housing 2, stator assembly 3, and bearing 4 are provided. The end of the rotor assembly 1 can be connected to one axial end of the rotor housing 2 so that the rotor assembly 1 can rotate integrally with the rotor housing 2. The bearing 4 is located on the inner circumference of one axial end of the rotor housing 2 to support the rotor housing 2. The other axial end of the rotor housing 2 extends to the radial outer circumference of at least a portion of the structure of the stator assembly 3. The rotor housing 2 can be driven to rotate by the stator assembly 3 so as to drive the rotor assembly 1 to rotate integrally.

[0033] This invention, through the configuration of the rotor housing, allows one axial end to be integrated with the rotor assembly, enabling them to rotate as a single unit. The other end of the rotor housing extends to the radial outer periphery of the stator assembly, allowing the stator assembly to drive the rotor housing to rotate. A bearing is positioned at the junction of the rotor housing and the rotor assembly, simultaneously supporting both the rotor assembly and the rotor housing. Therefore, this application effectively eliminates the need for the rotor shaft to pass through the stator, allowing for effective support of both the rotor assembly and the rotor housing with a single bearing. The stator side does not require a supporting bearing, thus effectively reducing the need for a bearing. Compared to existing conventional external rotor motor structures that require two bearings or a long bearing, this invention effectively saves the cost of a small but expensive bearing, thereby reducing the cost of the external rotor motor and also reducing noise and vibration.

[0034] This invention features an integrated rotor design, significantly reducing manual installation time and greatly improving motor balance. Noise and vibration are significantly reduced compared to ordinary motors. The stator sleeve is simpler than existing structures, saving material costs. With the rotor shaft and stator located on opposite sides and the rotor shaft not passing through the stator, normal motor rotation is achieved using only a single bearing in the rotor bearing housing, saving the cost of one bearing. This further reduces noise and vibration while saving on material and labor costs. The novel external rotor of this invention is a single-bearing motor, reducing manual labor and material costs. The integrated rotor design improves motor consistency and significantly reduces motor noise and vibration.

[0035] The beneficial effects are as follows:

[0036] 1. The motor of the present invention adopts a single bearing design instead of a double bearing design. The rotor shaft does not pass through the stator. Only one bearing needs to be set on the rotor. The stator does not need a bearing. Unlike other existing conventional external rotor motor structures, which require two bearings or a long bearing, this invention saves the cost of a small but expensive bearing.

[0037] 2. The outer rotor of the present invention adopts an integrated design, which is composed of magnetic strips (magnetic materials are acceptable), rotor housing, bearing chamber, and rotor shaft. During the manufacturing of the outer rotor, the bearing is embedded in the bearing chamber of the housing. After the rotor shaft is tightly pressed with the outer end face of the bearing chamber, the whole is formed as one unit. The integrated rotor design reduces motor vibration and noise, and reduces labor hours.

[0038] 3. In this invention, the rotor shaft and stator are on opposite sides. One end of the rotor shaft is on the rotor bearing housing, and the other end is directly connected to the fan blade. Under the same motor installation dimensions, the rotor shaft length is greatly reduced, thus reducing the fluctuation during motor operation.

[0039] In this invention, the rotor shaft 11 and the stator core 31 in Figure 7 are arranged on both sides of the rotor housing 2. The rotor shaft 11 does not pass through the stator core 31 in Figure 7. The stator sleeve 33 in Figures 6a-6b does not need to be equipped with a bearing. Only one bearing 4 needs to be placed in the bearing chamber 40 of the rotor housing 2 to enable the motor to rotate normally. This realizes the motor design of using a single bearing instead of a double bearing, making it a single bearing motor.

[0040] In some embodiments, the rotor assembly 1 includes a rotor shaft 11, a first annular portion 12, and a first cylindrical body 13. The radial outer periphery of the rotor shaft 11 is connected to the radial inner periphery of the first annular portion 12. The first cylindrical body 13 is connected to the radial outer periphery of the first annular portion 12 and extends axially along the rotor shaft 11. The rotor housing 2 includes a second annular portion 21, a second cylindrical body 22, and a third cylindrical body 23. The second cylindrical body 22 is connected to the radial inner periphery of the second annular portion 21. The third cylindrical body 23 is connected to the radial outer periphery of the second annular portion 21 and extends axially to the radial outer side of the stator assembly 3. The first cylindrical body 13 is sleeved with the second cylindrical body 22 and can rotate integrally. The bearing 4 is located on the radial inner periphery of the second cylindrical body 22 to support the rotor housing 2. The stator assembly 3 can drive the third cylindrical body 23 to rotate, thereby driving the rotor shaft 11 to rotate.

[0041] This is a preferred structural form of the rotor assembly of the present invention. The structure of the first annular portion and the first cylindrical body can form a sleeve structure. The second cylindrical body on the rotor housing can be sleeved with the first cylindrical body to form an effective connection. The second annular portion and the third cylindrical body can be connected to the first cylindrical body as a whole. The second annular portion extends radially outward so that the third cylindrical body extends axially to the radial outer periphery of the stator assembly, thereby obtaining magnetic drive from the stator assembly, causing the third cylindrical body to rotate, and ultimately causing the rotor shaft to rotate. This eliminates the need for the rotor shaft to pass through to the other end of the stator assembly, effectively saving the arrangement of the bearing at the other end of the stator assembly and reducing costs.

[0042] The outer rotor of this invention adopts an integrated design, consisting of a magnetic strip (any magnetically conductive material is acceptable), a rotor housing, a bearing chamber, and a rotor shaft. During the manufacturing of the outer rotor, the bearing is embedded inside the bearing chamber of the housing. After the rotor shaft is tightly pressed against the outer end face of the bearing chamber, the entire assembly is formed as one piece. This integrated rotor design reduces motor vibration and noise, and decreases labor time. In this invention, the rotor shaft and stator are located on opposite sides. One end of the rotor shaft is on the rotor bearing chamber, and the other end is directly connected to the fan blade. With the same motor installation dimensions, the rotor shaft length can be significantly reduced, thus reducing vibration during motor operation.

[0043] In some embodiments, the first cylindrical body 13 is sleeved on the outer periphery of the second cylindrical body 22, and the two are fixed together by interference fit, threaded fastening, or snap fastening. The outer ring of the bearing 4 rotates integrally with the second cylindrical body 22. The first annular portion 12 is a circular ring structure, the first cylindrical body 13 is a cylindrical structure without bottoms at both ends, the second annular portion 21 is a circular ring structure, and the second cylindrical body 22 and the third cylindrical body 23 are both cylindrical structures without bottoms at both ends. This is the preferred fit between the first and second cylindrical bodies of the present invention. The two can be fixed together by interference fit or other means. The first, second, and third cylindrical bodies are all structures without bottoms at both ends, which facilitates matching and assembly with other structures such as the annular portion. The first and second annular portions are circular ring structures, which facilitates fitting with the cylindrical body structure for assembly or as a sleeve structure for receiving magnetic forces.

[0044] In some embodiments, the stator assembly 3 includes a stator core 31, a stator coil 32, and a stator sleeve 33. The stator sleeve 33 passes through the radial inner circumference of the stator core 31 to fix the stator core 31. A stator shaft 34 is also fixedly connected to one end of the stator sleeve 33 facing the rotor assembly 1. The stator shaft 34 passes through the inner circumference of the bearing 4 to support the bearing 4. This is a preferred structural form of the stator assembly of the present invention, in which the stator core and stator coil can generate a magnetic field by being energized, and generate a magnetic force with the magnetic structure on the rotor housing, thereby driving the third cylinder to rotate, and ultimately driving the rotor shaft to rotate. The stator sleeve is used to fix the stator core and also to support the radial inner end of the bearing, so that the outer ring of the bearing rotates with the rotor housing, while the inner ring of the bearing remains stationary, forming a support for the rotor housing and the rotor assembly.

[0045] In some embodiments, the rotor housing 2 further includes a fourth cylindrical body 24 and a third annular portion 25. One axial end of the fourth cylindrical body 24 is connected to the shaft end of the second cylindrical body 22, and the other axial end of the fourth cylindrical body 24 extends axially away from the second cylindrical body 22. The outer radial end of the third annular portion 25 is connected to the inner radial circumference of the fourth cylindrical body 24, and the third annular portion extends radially inward. The third annular portion 25 can axially limit one axial end of the bearing 4, and the first annular portion 12 of the rotor assembly 1 can axially limit the other axial end of the bearing 4. The bearing 4 is disposed within the space enclosed by the first annular portion 12, the second cylindrical body 22, the fourth cylindrical body 24, the third annular portion 25, and the stator shaft 34, and the space forms a bearing chamber 40. The rotor housing of the present invention further preferably includes a fourth cylindrical body and a third annular portion, which can form a limiting structure extending toward the stator core, thereby limiting and locking the axial movement of the bearing toward the stator. The other axial end of the bearing is limited and locked by the first annular portion of the rotor assembly.

[0046] In some embodiments, the second cylindrical body 22 is connected to one axial end of the second annular portion 21, and the fourth cylindrical body 24 is connected to the other axial end of the second annular portion 21, such that the second annular portion 21 is located between the second cylindrical body 22 and the fourth cylindrical body 24. The inner and outer diameters of the second cylindrical body 22 and the fourth cylindrical body 24 are the same, and they can be integrally manufactured. The radially outer end of the third annular portion 25 is connected to the radially inner end at the free end of the fourth cylindrical body 24. This is a further preferred structural form of the second and fourth cylindrical bodies of the present invention, that is, the second and fourth cylindrical bodies are respectively located at the two axial ends of the second annular portion, such that the second cylindrical body is used to form a sleeve with the first cylindrical body of the rotor assembly, and the fourth cylindrical body is used to extend towards the stator to form a space for the bearing chamber, and the bearing is limited by the third annular portion.

[0047] In some embodiments, a magnetic structure 5 is provided on at least one of the second annular portion 21 and the third cylindrical body 23 of the rotor housing 2. The magnetic structure 5 is disposed on the side of at least one of the second annular portion 21 and the third cylindrical body 23 facing the stator core 31. By providing a magnetic structure on at least one of the structures of the second annular portion and the third cylindrical body, the present invention can sense the magnetic field of the stator core and the coils, thereby driving them to move.

[0048] This invention applies to the field of electric motors. This motor is an external rotor single-bearing DC motor. The rotor rotates while the stator remains stationary. It includes an integrated rotor, a stator sleeve, a stator core with windings, and a controller.

[0049] As shown in Figure 5 before assembly, the integrated external rotor after assembly is shown in Figure 4. It consists of a magnetic structure 5 (preferably a magnetic strip), a rotor housing 2, a bearing chamber 40, a bearing 4, a rotor shaft 11, and a fastening ring on the rotor shaft 11 (including a first annular portion 12 and a first cylindrical body 13). The bearing chamber 40 is embedded in the middle of the rotor housing 2. After the rotor housing 2 is cast, the magnetic strip is placed on the inner cavity of the rotor housing 2. The bearing 4 is pressed into the bearing chamber 40. The bearing chamber 40 has only one end face as the inner end face, which has only a hole slightly larger than the bearing fixing post on the sleeve, and the rest is closed. The outer side has no end face, and it only has the bearing chamber side (second cylindrical body 22) on the outer side of the housing. The rotor shaft 11 and the fastening ring on the rotor shaft are integrated. After the bearing 4 is pressed in, the fastening ring is pressed into the bearing chamber side on the outer side of the housing to complete the assembly of the entire integrated rotor, as shown in Figure 4.

[0050] In some embodiments, a control plate 6 is further provided on the stator sleeve 33. The control plate 6 has an annular plate structure and is sleeved on the stator sleeve 33. The present invention also enables effective control of the energization of the stator coil through the provision of the control plate.

[0051] In some embodiments, at least one of the outer periphery of the stator sleeve 33 and the inner periphery of the stator core 31 is provided with a protruding ridge 35, and the other is provided with at least one groove 36, with the protruding ridge 35 and the groove 36 correspondingly interlocking. The present invention also utilizes the concave-convex fit structure at the junction of the stator sleeve and the stator core to enable them to perform positioning and limiting functions, and to provide effective and robust support for the stator core.

[0052] As shown in Figures 6a-6b, the stator sleeve has a mounting bracket 37. The surface of the sleeve is provided with a raised rib 35 for fixing the stator core of Figure 7. The stator core of Figure 7 is provided with a corresponding groove 36, which matches and fixes the raised rib 35 of the stator sleeve. The mounting bracket 37 of the stator sleeve 33 is provided with a ramp groove 38 for fixing the motor control board 6. The sleeve is also provided with a bearing fixing post (stator shaft 34), which is fixed to the inner ring of the bearing 4 on the integral rotor of Figure 5.

[0053] The specific installation method of this invention is as follows: First, press the control plate 6 into the inclined groove 38 of the stator sleeve 33 in Figures 6a-6b and fix it. Then, press the stator core 31 with windings in Figure 7 into the stator sleeve 33. The groove 36 and the protrusion 35 of the stator core 31 in Figure 7 are tightly fitted and fixed (not limited to this type of fit). Then, the bearing fixing column (stator shaft 34) on the stator sleeve 33 in Figures 6a-6b is interference-fitted with the inner ring of the bearing 4 on the integral rotor in Figure 5 (not limited to this type of fit). The stator sleeve 33 in Figures 6a-6b with control plate and stator core is pressed into the stator sleeve 33. The entire external rotor DC motor is installed by inserting the rotor into the rotor housing. The motor after installation is shown in Figures 2a-2b. Since the rotor shaft 11 is fitted onto the bearing chamber side (i.e., the second cylinder 22) of the rotor housing 2 via a fastening ring (including the first annular part 12 and the first cylinder 13), the entire rotor rotates as a whole. It does not pass through the stator sleeve 33 in Figures 6a-6b. The sleeves in Figures 6a-6b, the stator core 31 in Figure 7, and the controller (i.e., the control board 6) fixed on the load are all stationary. Therefore, there is no need for a bearing to support the rotation on the sleeve. Only a conventional bearing 4 is needed on the external rotor housing.

[0054] The mounting bracket on the motor is fixed to the customer's load. The stator sleeve, the controller on top, the stator core, and the inner ring of the bearing are fixed. When the motor is powered on, the rotor housing rotates, which drives the outer ring of the bearing, the rotor shaft, and the fan blades on the rotor shaft to rotate. The exploded view of the motor is shown in Figure 7. The sectional view of the motor after assembly is shown in Figure 5.

[0055] In some embodiments, the external rotor motor is a DC motor.

[0056] The inventive points of this invention are as follows:

[0057] 1. The external rotor motor of the present invention adopts a single bearing design instead of a double bearing design, which is a single bearing motor and reduces costs.

[0058] 2. The outer rotor of the present invention adopts an integrated design, which is composed of magnetic strips, rotor housing, bearing chamber and rotor shaft as one unit, which reduces noise and reduces manual processing time.

[0059] 3. In this invention, the rotor shaft and stator are on opposite sides, and the rotor shaft does not pass through the stator. It is on the opposite side of the stator, which greatly shortens the length of the rotor shaft and improves the motor balance.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. An external rotor motor, characterized in that: include: The rotor assembly (1), rotor housing (2), stator assembly (3), and bearing (4) are provided. The end of the rotor assembly (1) can be connected to one axial end of the rotor housing (2) so that the rotor assembly (1) can rotate integrally with the rotor housing (2). The bearing (4) is located on the inner circumference of one axial end of the rotor housing (2) to support the rotor housing (2). The other axial end of the rotor housing (2) extends to the radial outer circumference of at least a portion of the structure of the stator assembly (3). The rotor housing (2) can be driven to rotate by the stator assembly (3) to drive the rotor assembly (1) to rotate integrally. The rotor assembly (1) includes a rotor shaft (11), a first annular portion (12), and a first cylindrical body (13). The radial outer circumference of the rotor shaft (11) and the radial outer circumference of the first annular portion (12) are connected to each other. The first cylindrical body (13) is connected to the radial outer periphery of the first annular portion (12) and extends axially along the rotor shaft (11). The rotor housing (2) includes a second annular portion (21), a second cylindrical body (22), and a third cylindrical body (23). The second cylindrical body (22) is connected to the radial inner periphery of the second annular portion (21), and the third cylindrical body (23) is connected to the radial outer periphery of the second annular portion (21) and extends axially to the radial outer side of the stator assembly (3). The first cylindrical body (13) is sleeved with the second cylindrical body (22) and can rotate as a whole. The bearing (4) is located on the radial inner periphery of the second cylindrical body (22) to support the rotor housing (2). The stator assembly (3) can drive the third cylindrical body (23) to rotate, thereby driving the rotor shaft (11) to rotate.

2. The external rotor motor according to claim 1, characterized in that: The first cylinder (13) is sleeved on the outer periphery of the second cylinder (22), and the two are fixed together by interference fit, thread fastening or snap fastening. The outer ring of the bearing (4) rotates together with the second cylinder (22). The first annular part (12) is a circular ring structure, the first cylinder (13) is a cylindrical structure without bottom at both ends, the second annular part (21) is a circular ring structure, and the second cylinder (22) and the third cylinder (23) are both cylindrical structures without bottom at both ends.

3. The external rotor motor according to claim 1, characterized in that: The stator assembly (3) includes a stator core (31), a stator coil (32), and a stator sleeve (33). The stator sleeve (33) passes through the radial inner circumference of the stator core (31) to fix the stator core (31). A stator shaft (34) is also fixedly connected to one end of the stator sleeve (33) facing the rotor assembly (1). The stator shaft (34) passes through the inner circumference of the bearing (4) to support the bearing (4).

4. The external rotor motor according to claim 3, characterized in that: The rotor housing (2) further includes a fourth cylinder (24) and a third annular portion (25). One axial end of the fourth cylinder (24) is connected to the shaft end of the second cylinder (22), and the other axial end of the fourth cylinder (24) extends axially away from the second cylinder (22). The outer radial end of the third annular portion (25) is connected to the inner radial circumference of the fourth cylinder (24), and the third annular portion extends radially inward. The third annular portion (25) can axially limit one axial end of the bearing (4), and the first annular portion (12) of the rotor assembly (1) can axially limit the other axial end of the bearing (4). The bearing (4) is disposed in the space enclosed by the first annular portion (12), the second cylinder (22), the fourth cylinder (24), the third annular portion (25), and the stator shaft (34), and the space is formed as a bearing chamber.

5. The external rotor motor according to claim 4, characterized in that: The second cylindrical body (22) is connected to one axial end of the second annular portion (21), and the fourth cylindrical body (24) is connected to the other axial end of the second annular portion (21), such that the second annular portion (21) is located between the second cylindrical body (22) and the fourth cylindrical body (24). The inner diameter and outer diameter of the second cylindrical body (22) and the fourth cylindrical body (24) are the same, and the two can be manufactured as one piece. The radial outer end of the third annular portion (25) is connected to the radial inner end of the free end of the fourth cylindrical body (24).

6. The external rotor motor according to claim 3, characterized in that: A magnetic structure (5) is provided on at least one of the second annular portion (21) and the third cylindrical body (23) of the rotor housing (2), and the magnetic structure (5) is provided on the side of at least one of the second annular portion (21) and the third cylindrical body (23) facing the stator core (31).

7. The external rotor motor according to claim 3, characterized in that: The stator sleeve (33) is also provided with a control plate (6), which is a ring-shaped plate structure and is sleeved on the stator sleeve (33).

8. The external rotor motor according to claim 3, characterized in that: At least one of the outer periphery of the stator sleeve (33) and the inner periphery of the stator core (31) is provided with a protrusion (35), and the other is provided with at least one groove (36). The protrusion (35) and the groove (36) are inserted and engaged in a one-to-one correspondence.

9. The external rotor motor according to any one of claims 1-8, characterized in that: The external rotor motor is a DC motor.

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