Permanent magnet outer rotor type universal motor

Abstract

The invention discloses a permanent magnet outer rotor type universal motor. The invention aims to solve the problems of large axial size, incompact and cumbersome structure, poor heat dissipation efficiency and the like in the prior art. According to the technical scheme, the motor comprises a stator fixing body, a stator, a permanent magnet rotor, an output shaft, a centrifugal impeller, a machine shell, a control circuit board and a heat dissipation plate, the output shaft is rotationally matched with the stator fixing body, the permanent magnet rotor is fixed to the output shaft, the stator is fixed to the stator fixing body and located on the inner side of the permanent magnet rotor, and the centrifugal impeller is fixed to the permanent magnet rotor. The casing is fixed on the rear side surface of the stator fixing main body, a partition plate is arranged in the casing to divide the space in the casing into a motor chamber and an air inlet chamber, an air inlet hole is formed in the central area of the partition plate, a heat dissipation plate is mounted on the rear side surface of the air inlet chamber, the control circuit board is fixedly mounted on the heat dissipation plate, an air inlet hole is formed in the bottom surface of the air inlet chamber, and heat dissipation holes are formed in the stator fixing main body. A threading hole channel is formed in the side wall of the motor chamber, and a stator power line is connected with the control circuit board through the threading hole channel.

Description

Technical Field

[0001] This invention relates to an electric motor that provides rotational power, and in particular to a permanent magnet external rotor type universal motor. Background Technology

[0002] Traditional general-purpose electric motors are mostly internal rotor motors. These motors have a large axial dimension and a cast iron housing. Although there is an axial flow impeller inside the housing, the airflow inside the housing is not smooth, so the outer surface of the housing must be covered with heat dissipation fins. In addition, an electrical control box must be installed outside the housing to install the control circuit. The motor feet are cast together with the housing. Therefore, the motor has a large axial dimension, a non-compact structure, and is quite bulky, which affects its ease of use and wide range of applications. In particular, it is not convenient to install it on mobile devices.

[0003] Chinese Patent Publication No. CN223141733U discloses an external rotor motor, the structure of which includes a housing, an inner stator, an outer rotor, a shaft, a fan cover, a fan, and a control box. The housing has a left end cover and a right end cover at its two ends. The shaft passes sequentially through the left end cover, the housing, and the right end cover, and is rotatably connected to both the left and right end covers. The inner stator is fixedly connected to the right end cover. The inner stator includes a yoke and multiple pole posts, which are spaced apart along the outer circumference of the yoke. Each pole post is wound with metal wire. The outer rotor comprises a disc-shaped rotor body, an annular mounting portion, and permanent magnet blocks spaced apart along the inner circumference of the mounting portion. The rotor body is fixedly connected to the rotating shaft. The mounting portion is fitted onto the outer side of the inner stator. The magnetic poles of the permanent magnet blocks are radially distributed along the outer rotor, and the inner surfaces of adjacent permanent magnet blocks have opposite magnetic properties. The control box can control the current direction in each metal coil. The fan is fixedly connected to the rotating shaft and located on the right side of the right end cover. A fan shroud is fitted onto the outer side of the fan and is fixedly connected to the housing. This external rotor universal motor adopts the common structure of the aforementioned traditional AC universal motor, thus suffering from many problems associated with the traditional AC universal motor structure, resulting in a large axial dimension, non-compact structure, and considerable weight, affecting ease of use and wide applicability.

[0004] Chinese Patent Announcement No. CN222785839U discloses a novel external rotor permanent magnet DC brushless motor, which is used in new energy vehicles to drive engine cooling fans. The structure includes an external rotor, a stator, a flange, a motor shaft, and a top cover. The motor shaft is die-cast onto the center of the flange and passes through the stator connecting flange. The flange and top cover are connected by rivets. The stator includes a plastic insulating base frame and a plastic insulating upper frame connected to the outside of the plastic insulating base frame. Three-phase copper plastic sheets and stator silicon steel sheets are installed on the plastic insulating base frame and the plastic insulating upper frame. Enamelled round copper wire windings are provided on the outer side of the stator silicon steel sheets and the plastic insulating upper frame. A threaded hole boss for fixing the stator and a waterproof vent valve are installed on the side of the flange near the stator. The stator is connected to the flange, and multiple magnetic tiles are installed on the inner wall of the external rotor. The shortcomings of this technical solution are as follows: First, because there is no outer casing, the outer rotor is exposed and directly connected to the engine cooling fan through the outer side of the outer rotor. There is no drive shaft for rotational power output, so it can only be used as a dedicated fan motor and cannot be used as a general-purpose motor, thus limiting its application range. Second, there is no motor cooling fan, and the control circuit board is enclosed in the flange, relying only on the ribs on the outside of the flange for heat dissipation. Therefore, the heat dissipation of the motor and control circuit board is poor, affecting the motor's working performance.

[0005] Chinese Patent Publication No. CN119561319A discloses an integrated motor and controller device for eVTOL, which is an external rotor motor used in UAVs to drive rotors. The structure includes an integrated cooling fan assembly, a motor assembly, and a controller assembly. The motor shaft is fixed to the cooling fan and also serves as the fan's rotating shaft, forming the integrated cooling fan assembly. The motor assembly is an external rotor with an inner stator structure, including a rotor component, a stator component, bearings, and a stator support. The stator component is fixed to the stator support, and the rotor component is mounted on the cooling fan. The rotor component and the stator component are connected by bearings. The rotor component includes a rotor housing, a rotor core, and a permanent magnet array. The array is mounted on the rotor core and integrally mounted on the rotor housing. The stator components include: an internal stator support with heat dissipation fins, a stator core, and stator windings. The internal stator support is located at the center of the motor, and the stator core and stator windings are mounted on the outer side of the internal stator support. The controller assembly includes: a connecting frame, a capacitor board, a drive board, an adapter board, a heat sink, a housing, a mounting base, a power board, a first control board, and a capacitor. The capacitor is fixed on the capacitor board, and the capacitor board, adapter board, drive board, power board, first control board, and second control board are fixed on the heat sink to form a heat dissipation structure. The heat dissipation structure is located inside the housing, and the housing is fixed inside the connecting frame. One end of the connecting frame is connected to the stator support, and the other end of the connecting frame is connected to the housing and the mounting base. The drawback of this rotor-specific motor is that, in addition to its limited application range, although a cooling fan is provided, it is a centrifugal fan without a housing. The fan exhausts air outwards and does not pass through the center of the motor assembly and controller assembly, resulting in poor heat dissipation efficiency. Summary of the Invention

[0006] In order to overcome the problems of existing general-purpose electric motors, such as large axial dimensions, non-compact and heavy structure, which affect ease of use and wide application, poor heat dissipation of motor and control circuit board, which affects motor performance, the purpose of this invention is to provide an improved permanent magnet external rotor general-purpose motor that can overcome the defects of the prior art.

[0007] The technical solution adopted by this invention to solve its technical problem is: a permanent magnet external rotor universal motor, comprising a stator fixing body, a stator, a permanent magnet rotor, an output shaft, a centrifugal impeller, a housing, a control circuit board, and a heat sink, characterized in that: the output shaft is rotatably fitted on the bearing seat of the stator fixing body via a bearing; the permanent magnet rotor is fixed to the inner end of the output shaft; the outer end of the output shaft serves as the rotational power output end; the stator is fixed to the inner side of the stator fixing body and is located between the inner side of the permanent magnet rotor and the bearing seat; the centrifugal impeller is fixed to the rear side of the permanent magnet rotor; the housing is fixed to the rear side of the stator fixing body by its front end face and houses the permanent magnet rotor and the centrifugal impeller therein; a partition plate is provided inside the housing behind the centrifugal impeller, the partition plate separating the housing... The internal space is divided into a motor chamber and an air intake chamber. The central area of ​​the partition plate has an air intake hole for the motor chamber. The rear side of the air intake chamber opposite to the partition plate has a heat dissipation plate window. The heat dissipation plate is installed on the heat dissipation plate window with its heat dissipation surface facing outwards from the casing. The control circuit board is installed and fixed on the inner side of the heat dissipation plate inside the air intake chamber. The bottom surface of the air intake chamber has an air intake hole. The stator fixing body has a heat dissipation hole for the motor chamber. The side wall of the motor chamber has a wiring channel isolated from the motor chamber. One end of the wiring channel leads to the air intake chamber, and the other end leads to the front end of the casing. The power line of the stator passes through the wiring channel and connects to the control signal output terminal of the control circuit board. The connecting wire of the power supply terminal of the control circuit board extends outwards from the casing.

[0008] The permanent magnet rotor described in the above technical solution can be composed of a rotor yoke with an inner cavity and a plurality of permanent magnet plates evenly distributed on the inner cavity wall of the rotor yoke, wherein the magnetic properties of adjacent permanent magnet plates facing the stator are opposite, the hub of the permanent magnet rotor is located at the center of the bottom surface of the inner cavity of the rotor yoke, and the hub is connected to the inner end of the output shaft by a key; the stator is composed of a stator core and stator windings evenly distributed in the grooves on the outer side of the stator core, and the stator is mounted and fixed on the inner side of the stator fixing body and located in the inner cavity of the rotor yoke.

[0009] The bearing housing described in the above technical solution can accommodate two bearings, and a retaining ring can be provided between the two bearings in the bearing housing for separation. The cover on the bearing housing is located inside the stator fixing body.

[0010] The lower part of the stator fixing body described in the above technical solution can be connected to a motor foot, and the motor foot is provided with a foot extending to the rear of the motor.

[0011] The top side of the air intake chamber described in the above technical solution may be provided with an operation panel window leading to the outside of the housing. An operation panel is installed on the operation panel window, with the operation surface of the operation panel facing outward. The operation signal output terminal of the operation panel is connected to the operation signal input terminal of the control circuit board.

[0012] The above-described technical solution provides wire-passing channels on the four side walls of the motor compartment at the upper left, upper right, lower left, and lower right positions of the cross-section, respectively, to facilitate wire passing.

[0013] The outer diameter of the centrifugal impeller described in the above technical solution can be equivalent to the outer diameter of the permanent magnet rotor. The centrifugal impeller is fixed to the rear side of the permanent magnet rotor by screws. The axis of the centrifugal impeller is coaxially arranged with the central area of ​​the air inlet of the motor chamber on the partition plate. The outer diameter of the central area of ​​the partition plate is equivalent to the inner diameter of the centrifugal impeller.

[0014] In the above technical solution, the stator is fixed to the outer side of the bearing seat on the inner side of the stator fixing body by screw one; the housing is fixed to the rear side of the stator fixing body by screw two; the partition plate is fixed to the protruding part of the inner wall of the housing by screw three; the heat sink is fixed to the heat sink window on the rear side of the air intake chamber by screw four; the control circuit board is fastened to the inner side of the heat sink by screws or glue; the motor base is fixed to the lower part of the stator fixing body by screw five; and the operation panel is glued to the operation panel window.

[0015] The beneficial effects of this invention are as follows: First, the output shaft is rotatably fitted onto the bearing seat of the stator fixing body via a bearing. The permanent magnet rotor is fixed to the inner end of the output shaft, and the outer end of the output shaft serves as the rotational power output end. The stator is fixed to the inner side of the stator fixing body and is located between the inner side of the permanent magnet rotor and the bearing seat. The centrifugal impeller is fixed to the rear side of the permanent magnet rotor. The front end face of the housing is fixed to the rear side face of the stator fixing body and houses the permanent magnet rotor and the centrifugal impeller. Thus, a simple and reasonable permanent magnet external rotor type universal motor is constructed, which has a small motor shaft size, compact structure, convenient use, and wide applicability. Secondly, because a partition plate is provided inside the casing behind the centrifugal impeller, the internal space of the casing is divided into a motor chamber and an air intake chamber. An air intake hole for the motor chamber is located in the central area of ​​the partition plate, and an air intake hole for the air intake chamber is also located on the bottom surface of the air intake chamber. The stator fixing body has heat dissipation holes for the motor chamber. When the permanent magnet rotor rotates, driving the centrifugal impeller to rotate, a negative pressure is generated in the central area of ​​the centrifugal impeller. This causes air from outside the casing to enter the air intake chamber through the air intake hole on the bottom surface of the air intake chamber, and then pass through the central area of ​​the partition plate. After entering the motor chamber through the air inlet, the air is drawn into the central area of ​​the centrifugal impeller and flung towards the outer diameter of the impeller by the blades. Then, guided by the inner wall of the motor chamber, the air passes through the gaps on the stator and its surrounding gaps, and is finally blown out of the casing through the heat dissipation holes on the stator fixing body. Therefore, the heat dissipation airflow inside the casing is smooth and the heat dissipation efficiency is good, ensuring the working efficiency of the motor. Moreover, it is not necessary to use a bulky casing with metal castings and heat dissipation fins on the outside; a lightweight casing made of plastic or similar materials can be used, making the motor lighter overall and providing convenience for actual use. Thirdly, since the air intake chamber has a heat dissipation plate window on its rear side opposite to the partition plate, and the heat dissipation plate is installed on the heat dissipation plate window with its heat dissipation surface facing outwards from the casing, and the control circuit board is installed and fixed on the inner side of the heat dissipation plate inside the air intake chamber, there is no need to set up a separate electrical control box fixed outside the casing for the control circuit board. This also makes the overall structure of the motor more compact and aesthetically pleasing. The control circuit board not only dissipates heat through the heat dissipation plate, but is also located in the motor's heat dissipation airflow path inside the air intake chamber, so the control circuit board can obtain better heat dissipation, further ensuring the stable operation of the motor.Fourth, the side wall of the motor compartment is provided with a wiring channel that is isolated from the motor compartment. One end of the wiring channel leads to the air intake chamber and the other end leads to the front end of the housing. The power line of the stator is connected to the control terminal of the control circuit board through the wiring channel. Therefore, when the power line of the stator is connected to the control terminal of the control circuit board, it will not interfere with the permanent magnet rotor and centrifugal impeller in the motor compartment. This can effectively reduce the motor failure rate and greatly facilitate the wiring of the power line in the motor.

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a cross-sectional schematic diagram of an embodiment of the present invention, in which the connecting wires between the stator, the control circuit board and the operation board are omitted.

[0018] Figure 2 yes Figure 1 The schematic diagram shows the components separated, but the stator fixing body, stator, permanent magnet rotor and centrifugal impeller are not cut apart.

[0019] Figure 3 yes Figure 1 A diagram showing the view from the right.

[0020] Figure 4 yes Figure 3 A diagram showing the removal of the heat sink (along with the control circuit board).

[0021] Figure 5 yes Figure 2 A schematic diagram of the left side of the middle casing.

[0022] Figure 6 yes Figure 1 A left-side view diagram.

[0023] In the diagram: 1. Stator fixing body; 2. Stator; 3. Permanent magnet rotor; 4. Output shaft; 5. Centrifugal impeller; 6. Housing; 7. Control circuit board; 8. Heat sink; 9. Bearing; 10. Inner end of output shaft; 11. Bearing housing; 12. Partition plate; 13. Motor compartment; 14. Air inlet chamber; 15. Air inlet of motor compartment; 16. Rear side of air inlet chamber; 17. Heat sink window; 18. Air inlet of air inlet chamber; 19. 20. Heat dissipation hole; 21. Wire hole; 22. Rotor yoke; 23. Permanent magnet plate; 24. Hub; 25. Stator core; 26. Stator winding; 27. Snap ring; 28. Seat cover; 29. ​​Motor foot; 30. Machine foot; 31. Control panel window; 32. Control panel; 33. Screw 1; 34. Screw 2; 35. Screw 3; 36. Protruding part on the inner wall of the housing; 37. Screw 4; 38. Screw 5. Detailed Implementation

[0024] Reference Figures 1-6 This permanent magnet external rotor general-purpose motor includes a stator fixing body 1, a stator 2, a permanent magnet rotor 3, an output shaft 4, a centrifugal impeller 5, a housing 6, a control circuit board 7, and a heat sink 8. Its features are: the output shaft 4 is rotatably fitted onto the bearing seat 11 of the stator fixing body 1 via a bearing 9; the permanent magnet rotor 3 is fixed to the inner end 10 of the output shaft 4, with the outer end of the output shaft serving as the rotational power output end; the stator 2 is fixed to the inner side of the stator fixing body 1 and is located between the inner side of the permanent magnet rotor 3 and the bearing seat 11; the centrifugal impeller 5 is fixed to the rear side of the permanent magnet rotor 3; the housing 6 is fixed to the rear side of the stator fixing body 1 by its front end face and houses the permanent magnet rotor 3 and the centrifugal impeller 5; a partition plate 12 is provided inside the housing 6 behind the centrifugal impeller 5, dividing the internal space of the housing 6 into a motor chamber 13 and an air intake chamber. The unit consists of two parts: a central area of ​​the partition plate 12 with an air inlet 15 for the motor chamber; a rear side 16 of the air inlet chamber 14 opposite to the partition plate 12 with a heat dissipation window 17; a heat dissipation plate 8 mounted on the heat dissipation window 17 with its heat dissipation surface facing outwards from the housing 6; a control circuit board 7 mounted and fixed on the inner side of the heat dissipation plate 8 within the air inlet chamber 14; an air inlet 18 on the bottom surface of the air inlet chamber 14; a heat dissipation hole 19 for the motor chamber 13 on the stator fixing body 1; a wiring channel 20 isolated from the motor chamber 13 on the side wall of the motor chamber 13; one end of the wiring channel 20 leading to the air inlet chamber 14 and the other end leading to the front end of the housing 6; the power line of the stator 2 connected to the control signal output terminal of the control circuit board 7 through the wiring channel 20; and the power supply terminal of the control circuit board 7 led out of the housing 6 by a wire through a wire hole 21.

[0025] In addition, the permanent magnet rotor 3 is composed of a rotor yoke 22 with an inner cavity and a plurality of permanent magnet plates 23 evenly distributed on the inner cavity wall of the rotor yoke 22. The magnetic properties of adjacent permanent magnet plates 23 facing the stator 2 are opposite. The hub 24 of the permanent magnet rotor 3 is located at the center of the bottom surface of the inner cavity of the rotor yoke 22. The hub 24 is connected to the inner end 10 of the output shaft 4 by a key. The stator 2 is composed of a stator core 25 and stator windings 26 evenly distributed in the grooves on the outer side of the stator core 25. The stator 2 is mounted and fixed on the inner side of the stator fixing body 1 and located in the inner cavity of the rotor yoke 22.

[0026] Two bearings 9 are installed in the bearing housing 11. A retaining ring 27 is provided between the two bearings 9 in the bearing housing 11 for separation. The cover 28 on the bearing housing 24 is located inside the stator fixing body 1.

[0027] The lower part of the stator fixing body 1 is connected to a motor foot 29, and the motor foot 29 is provided with a foot 30 extending to the rear of the motor.

[0028] The top side of the air intake chamber 14 is provided with an operation panel window 31 leading to the outside of the housing 6. An operation panel 32 is installed on the operation panel window 31. The operation surface of the operation panel 32 faces outward. The operation signal output terminal of the operation panel 32 is connected to the operation signal input terminal of the control circuit board 7.

[0029] The motor chamber 13 has wire-passing holes 20 on its four side walls at the upper left, upper right, lower left, and lower right positions of the cross section to facilitate wire passing.

[0030] The outer diameter of the centrifugal impeller 5 is equivalent to the outer diameter of the permanent magnet rotor 3. The centrifugal impeller 5 is fixed to the rear side of the permanent magnet rotor 3 by screws. The axis of the centrifugal impeller 3 is coaxially arranged with the central area of ​​the partition plate 12. The outer diameter of the central area of ​​the air inlet 15 area of ​​the motor chamber is equivalent to the inner diameter of the centrifugal impeller 5.

[0031] The stator is fixed to the outer side of the bearing seat 11 on the inner side of the stator fixing body 1 by screw 33; the housing 6 is fixed to the rear side of the stator fixing body 1 by screw 34; the partition plate 12 is fixed to the protruding part 36 on the inner wall of the housing 6 by screw 35; the heat sink 8 is fixed to the heat sink window 17 on the rear side of the air intake chamber 14 by screw 37; the control circuit board 7 is fastened to the heat sink 8 by screws or glue; the motor base 29 is fixed to the lower part of the stator fixing body 1 by screw 38; the operation plate 32 is glued to the operation plate window 31.

[0032] During wiring, the power supply line of the stator 2 passes through the wire passage 20, crosses the motor chamber 13 to reach the air intake chamber 14, and then connects to the control signal output terminal of the control circuit board 7. The operation signal output terminal of the operation board 32 is connected to the operation signal input terminal of the control circuit board 7. The power supply terminal of the control circuit board 7 is led out of the housing 6 through the wire hole 21 via an external guide wire for connection to a common power supply. During operation, the permanent magnet rotor 3 is driven to rotate by the stator magnetic field, and the universal rotational power is output from the outer end of the output shaft. The rotation of the permanent magnet rotor 3 simultaneously drives the centrifugal impeller 5 to rotate. The central area of ​​the centrifugal impeller 5 generates a negative pressure, which allows air outside the casing 6 to enter the intake chamber 14 through the air inlet 18 on the bottom surface of the intake chamber 14, and then enter the motor chamber 13 through the air inlet 15 in the central area of ​​the partition plate 12. After entering the motor chamber 13, the air is sucked into the central area of ​​the centrifugal impeller 5, and is thrown to the periphery of the outer diameter of the centrifugal impeller 5 by the blades of the centrifugal impeller 5. Then, guided by the inner wall of the motor chamber 13, it passes through the gaps on the stator 2 and its surrounding gaps, and is blown out of the casing through the heat dissipation holes 19 on the stator fixing body 1. This allows the heat generated during the operation of the motor in the motor chamber 13 and the intake chamber 14 to be smoothly discharged outside the casing 6.

Claims

1. A permanent magnet external rotor type universal motor, comprising a stator fixing body, a stator, a permanent magnet rotor, an output shaft, a centrifugal impeller, a housing, a control circuit board, and a heat sink, characterized in that: The output shaft is rotatably fitted onto the bearing seat of the stator fixing body via a bearing. The permanent magnet rotor is fixed to the inner end of the output shaft, and the outer end of the output shaft serves as the rotational power output end. The stator is fixed to the inner side of the stator fixing body and is located between the inner side of the permanent magnet rotor and the bearing seat. The centrifugal impeller is fixed to the rear side of the permanent magnet rotor. The housing is fixed to the rear side of the stator fixing body by its front end face and houses the permanent magnet rotor and the centrifugal impeller. A partition plate is provided inside the housing behind the centrifugal impeller, dividing the internal space of the housing into a motor chamber and an air intake chamber. The central area of ​​the partition plate is provided for the air intake of the motor chamber. The air intake chamber has a heat dissipation plate window on its rear side opposite to the partition plate. The heat dissipation plate is installed on the heat dissipation plate window with its heat dissipation surface facing outwards from the housing. The control circuit board is installed and fixed on the inner side of the heat dissipation plate inside the air intake chamber. The bottom surface of the air intake chamber has an air intake hole. The stator fixing body has a heat dissipation hole for the motor chamber. The side wall of the motor chamber has a wiring channel isolated from the motor chamber. One end of the wiring channel leads to the air intake chamber, and the other end leads to the front end of the housing. The power line of the stator passes through the wiring channel and is connected to the control signal output terminal of the control circuit board. The connecting wire of the power supply terminal of the control circuit board is led out of the housing.

2. The permanent magnet external rotor universal motor according to claim 1, characterized in that: The permanent magnet rotor consists of a rotor yoke with an inner cavity and a plurality of permanent magnet plates evenly spaced on the inner cavity wall of the rotor yoke, wherein adjacent permanent magnet plates facing the stator have opposite magnetic properties. The hub of the permanent magnet rotor is located at the center of the bottom surface of the inner cavity of the rotor yoke, and the hub is connected to the inner end of the output shaft by a key. The stator consists of a stator core and stator windings evenly spaced in the grooves on the outer side of the stator core. The stator is mounted and fixed on the inner side of the stator fixing body and located in the inner cavity of the rotor yoke.

3. The permanent magnet external rotor universal motor according to claim 1 or 2, characterized in that: Two bearings are installed in the bearing housing, and a retaining ring can be provided between the two bearings in the bearing housing for separation. The cover on the bearing housing is located inside the stator fixing body.

4. The permanent magnet external rotor universal motor according to claim 1 or 2, characterized in that: The lower part of the stator fixing body is connected to a motor foot, and the motor foot is provided with a foot extending to the rear of the motor.

5. The permanent magnet external rotor universal motor according to claim 1 or 2, characterized in that: The top side of the air intake chamber is provided with an operation panel window leading to the outside of the housing. An operation panel is installed on the operation panel window with the operation surface of the operation panel facing outward. The operation signal output terminal of the operation panel is connected to the operation signal input terminal of the control circuit board.

6. The permanent magnet external rotor universal motor according to claim 1 or 2, characterized in that: The wiring channels are respectively provided on the four side walls of the motor room at the upper left, upper right, lower left and lower right positions of the cross section.

7. The permanent magnet external rotor universal motor according to claim 1 or 2, characterized in that: The outer diameter of the centrifugal impeller is equivalent to the outer diameter of the permanent magnet rotor. The centrifugal impeller is fixed to the rear side of the permanent magnet rotor by screws. The axis of the centrifugal impeller is coaxially arranged with the central area of ​​the air inlet of the motor chamber on the partition plate. The outer diameter of the central area of ​​the partition plate is equivalent to the inner diameter of the centrifugal impeller.

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