A plastic-free tubeless outer rotor motor

Abstract

This application discloses an external rotor motor without a plastic core tube, comprising: a stator core with a through-hole axially formed at its center and a plurality of winding slots axially formed at its periphery; a bearing fixedly installed in the through-hole; a rotor assembly including a rotor shaft coaxially passing through the shaft hole of the bearing and radially limited by the bearing; and a stator coated portion including a stator frame and an extension carrier; the stator frame covering the axial end face of the stator core and the inner wall of the winding slots; the extension carrier being fixedly connected to the stator frame and configured for connecting a base; this application has the effect of controlling the concentricity deviation between the bearing and the stator core to within 0.01 mm.

Description

Technical Field

[0001] This application relates to the field of external rotor motor technology, and in particular to an external rotor motor without a plastic center tube. Background Technology

[0002] An external rotor motor is a type of rotary motor in which the rotor is located on the outside and the stator is located inside. Unlike traditional internal rotor motors, its most distinctive feature is that the outer casing rotates while the center remains stationary. External rotor motors have advantages such as low speed and high torque, easy direct drive, and high system integration, and are therefore widely used in ventilation fans, pump loads, and household appliances.

[0003] In the existing external rotor motor structure, the plastic tube serves as the core load-bearing body, undertaking the function of connecting and positioning the stator core, bearings, and rotor. The specific assembly method is as follows: First, the bearing is pressed into the inner hole of the plastic tube with an interference fit; then, the stator core (usually made of multiple silicon steel sheets stacked together) is also fitted onto the outer wall of the plastic tube with an interference fit; subsequently, the rotor shaft passes through the inner diameter of the bearing, and the rotational positioning of the rotor assembly is achieved by utilizing the radial support of the oil-impregnated bearing.

[0004] However, because plastic tubes are usually made of plastic materials with poor stability, this traditional structure has significant technical defects in practical applications.

[0005] First, due to the characteristics of plastic injection molding process and the uneven shrinkage rate of materials, it is difficult to control the concentricity between the inner and outer diameters of the plastic tube with extreme precision during the processing. This limitation of the process directly leads to the deviation between the bearing center axis and the stator core center axis in the initial assembly stage.

[0006] Secondly, during long-term operation of the motor, the plastic tube is highly susceptible to irreversible material creep or physical aging due to the combined effects of ambient temperature fluctuations, motor temperature rise, and continuous mechanical stress. This further leads to the concentricity between the bearing and the stator core gradually deviating from the design tolerance.

[0007] The aforementioned large concentricity deviation will directly lead to uneven distribution of the magnetic air gap between the stator core and the rotor permanent magnet. The uneven magnetic air gap will cause the external rotor motor to generate periodic radial unbalanced force during rotation, which will induce obvious vibration and noise, seriously affecting the user experience.

[0008] Therefore, there is an urgent need to develop a new type of external rotor motor structure, which can solve the problem of poor concentricity caused by its reliance on a plastic tube by optimizing the connection architecture between the stator and the bearing. Summary of the Invention

[0009] In order to improve the technical problem of large deviation in concentricity between stator core and bearing caused by the use of plastic center tube in the prior art, this application provides an external rotor motor without plastic center tube.

[0010] The technical solution for an external rotor motor without a plastic core tube provided in this application is as follows: An external rotor motor without a plastic core tube includes: a stator core with a through-hole at its center and a plurality of winding slots along its periphery; a bearing fixedly installed in the center hole; a rotor assembly including a rotor shaft coaxially passing through the shaft hole of the bearing and radially limited by the bearing; and a stator coated portion including a stator frame and an extension carrier; the stator frame covering the axial end face of the stator core and the inner wall of the winding slots; and the extension carrier fixedly connected to the stator frame and configured for connecting a base.

[0011] Preferably, the bearing is an oil-impregnated bearing.

[0012] Preferably, the bearing is riveted into the center hole, and the bearing and the center hole are interference fit.

[0013] Preferably, the stator frame and the extension carrier are integrally formed.

[0014] Preferably, the extension carrier is fixed to the base by fasteners. The bottom of the extension carrier has several locking holes, and the base has mounting holes that correspond one-to-one with the locking holes. The locking holes are blind holes with internal threads. The shank of the fastener has external threads. The shank of the fastener passes through the mounting hole and is screwed into the corresponding locking hole until the head of the fastener abuts against the base, so that the extension carrier and the base are pressed together and fixed.

[0015] Preferably, the rotor assembly further includes: a rotor plastic-coated part, which is fixedly connected to the rotor shaft at its center; a motor housing, which is embedded in the inner side of the rotor plastic-coated part and located on the periphery of the rotor shaft; and a permanent magnet, which is fixedly installed on the inner circumference of the motor housing, and a magnetic air gap is defined between the permanent magnet and the outer circumference of the stator core.

[0016] Preferably, it also includes an electronic control board, which is fixedly installed on the stator rubber-coated part and located between the base and the stator core; a stator winding is wound on the stator core, and the stator winding is electrically connected to the electronic control board.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. By directly riveting the bearing into the center hole of the stator core with an interference fit, the concentricity deviation between the bearing and the stator core can be controlled within 0.01mm. Compared with the traditional structure that uses a plastic tube as the load-bearing body, this significantly reduces the problem of large concentricity deviation caused by the processing tolerance and material stability of the plastic tube. This, in turn, helps to improve the uniformity of the magnetic gap distribution between the permanent magnet and the stator core, reduce vibration and noise during operation, and extend the overall life of the motor. At the same time, the higher concentricity can effectively avoid the risk of mechanical interference between the stator core and the rotor assembly during assembly, and significantly improve the smoothness of assembly. 2. The stator coating section adopts an integrated injection molding design, which provides electrical insulation while the extension carrier provides a solid fixed support for the base. Several locking holes are provided on the extension carrier. The locking holes are blind holes with internal threads that mate with fasteners. During assembly, the fastener rod passes through the mounting hole and is screwed into the locking hole until the fastener head abuts against the base to generate a pre-tightening force, thereby fixing the extension carrier to the base. This structure supports efficient installation on one side, greatly improving assembly convenience and subsequent maintenance efficiency. 3. Oil-impregnated bearings are selected. Oil-impregnated bearings have the advantages of low cost, vibration absorption, low noise, and no need to add lubricating oil for a long working time. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the internal structure of an external rotor motor in the prior art; Figure 2 This is a schematic diagram of the structure of an external rotor motor without a plastic middle tube in this embodiment; Figure 3 This is a schematic diagram of the internal structure of an external rotor motor without a plastic tube in this embodiment; Figure 4 This is a schematic diagram of the structure of the stator core and the stator coating in this embodiment; Figure 5 This is another structural schematic diagram of the stator core and stator coating in this embodiment; Reference numerals: 100, Plastic core tube; 200, Existing stator core; 300, Existing bearing; 1, Stator core; 11, Center hole; 12, Winding slot; 2, Bearing; 3, Rotor assembly; 31, Rotor shaft; 32, Rotor plastic-coated part; 33, Motor housing; 34, Permanent magnet; 4, Stator plastic-coated part; 41, Stator frame; 42, Extension carrier; 421, Locking hole; 5, Base; 51, Mounting hole; 6, Electrical control board. Detailed Implementation

[0019] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0020] This application discloses an external rotor motor without a plastic middle tube.

[0021] Reference Figures 2 to 5 An external rotor motor without a plastic core tube includes a stator core 1, a bearing 2, a rotor assembly 3, a stator rubber-coated part 4, a base 5, and an electrical control board 6.

[0022] The stator core 1 is made of multiple silicon steel sheets stacked together. A through central hole 11 is opened in the center along the axial direction, and several winding slots 12 are evenly opened in the periphery along the axial direction. A stator winding (not shown in the figure) is wound on the stator core 1, and the bearing 2 is fixedly installed in the central hole 11.

[0023] In this embodiment, bearing 2 is an oil-impregnated bearing, which has the advantages of low cost, vibration absorption, low noise, and no need for lubrication during long working periods. By directly riveting bearing 2 into the center hole 11 of stator core 1, the outer diameter surface of bearing 2 and the inner wall surface of center hole 11 are configured as an interference fit. This application eliminates the traditional plastic tube support and utilizes the high rigidity and non-creep characteristics of silicon steel sheet to control the concentricity deviation between bearing 2 and stator core 1 within 0.01mm, thereby improving the uniformity of the magnetic gap distribution between permanent magnet and stator core and reducing vibration and noise during operation. At the same time, the high concentricity can effectively avoid the risk of mechanical interference between stator core 1 and rotor assembly 3 during assembly, and significantly improve the smoothness of assembly.

[0024] The rotor assembly 3 includes a rotor shaft 31, a rotor plastic-coated part 32, a motor housing 33, and a permanent magnet 34. The rotor shaft 31 is coaxially inserted into the shaft hole of the bearing 2 and is radially limited by the bearing 2. The center of the rotor plastic-coated part 32 is fixedly connected to the rotor shaft 31. The motor housing 33 is embedded inside the rotor plastic-coated part 32 and located outside the rotor shaft 31. The permanent magnet 34 is fixedly installed on the inner circumference of the motor housing 33, and a magnetic air gap is defined between the permanent magnet 34 and the outer circumference of the stator core 1.

[0025] The stator coating part 4 includes a stator frame 41 and an extension carrier 42, which are preferably integrally molded by injection molding. The stator frame 41 covers the axial end face (upper end face and lower end face) of the stator core 1 and the inner wall of the winding groove 12, which not only achieves electrical insulation, but also serves to fix the silicon steel sheet stack.

[0026] The extension carrier 42 is constructed to extend downwards from the stator core 1 and is used to connect the base 5. In this embodiment, the extension carrier 42 serves as a raised support structure between the stator core 1 and the base 5, maintaining a preset distance between the stator core 1 and the base 5 in the axial direction, thereby defining the axial space for the installation of the power control board 6 between them.

[0027] The control board 6 (i.e., the drive circuit board, PCB) is fixedly mounted on the stator coating part 4 and located in the axial space reserved by the extension carrier 42. The stator winding on the stator core 1 is electrically connected to the control board 6, thereby realizing the drive control of this application through the control board 6.

[0028] The extension carrier 42 has several locking holes 421, and the base 5 has mounting holes 51 that correspond one-to-one with the locking holes 421. The locking holes 421 are located at the bottom of the extension carrier 42. The locking holes 421 are blind holes with internal threads. The fastener is a screw. The shank of the fastener passes through the mounting hole 51 and is screwed into the corresponding locking hole 421 until the head of the fastener abuts against the base 5 to generate a pre-tightening force, so that the extension carrier 42 and the base 5 are fixedly connected. This structure supports efficient installation from one side of the bottom of the base 5, which greatly improves the assembly convenience and the efficiency of later maintenance. The installation process of an external rotor motor without a plastic tube disclosed in this application embodiment is as follows: First, fix the control board 6 on the extension carrier 42; then place the extension carrier 42 in the extension carrier and align the locking hole 421 with the corresponding mounting hole 51. The shank of the screw passes through the mounting hole 51 of the base 5 in sequence and is screwed into the corresponding locking hole 421 until the screw head abuts against the bottom surface of the base 5; continue to tighten the screw to generate a preload force, so that the screw head and the screw shank thread act on the base 5 and the extension carrier 42, thereby pressing the extension carrier 42 and the base 5 together and achieving detachable fixation.

[0029] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An external rotor motor without a plastic core tube, characterized in that, include: The stator core (1) has a through central hole (11) at its center along the axial direction, and several winding grooves (12) are provided at its periphery along the axial direction. The bearing (2) is fixedly installed in the central hole (11); The rotor assembly (3) includes a rotor shaft (31) which is coaxially inserted into the shaft hole of the bearing (2) and is radially limited by the bearing (2); The stator coating section (4) includes a stator frame (41) and an extension carrier (42); the stator frame (41) covers the axial end face of the stator core (1) and the inner wall of the winding groove (12); the extension carrier (42) is fixedly connected to the stator frame (41) and configured to connect to the base (5).

2. The external rotor motor without a plastic core tube according to claim 1, characterized in that: The bearing (2) is an oil-impregnated bearing.

3. An external rotor motor without a plastic core tube according to claim 1 or 2, characterized in that: The bearing (2) is riveted into the center hole (11), and the bearing (2) and the center hole (11) are interference fit.

4. The external rotor motor without a plastic core tube according to claim 1, characterized in that: The stator frame (41) and the extension carrier (42) are integrally formed.

5. The external rotor motor without a plastic core tube according to claim 1, characterized in that: The extension carrier (42) is fixed to the base (5) by fasteners; the bottom of the extension carrier (42) is provided with a plurality of locking holes (421), and the base (5) is provided with mounting holes (51) corresponding to the locking holes (421) one by one; the locking holes (421) are constructed as blind holes with internal threads, the rod of the fastener is provided with external threads, the rod of the fastener passes through the mounting hole (51) and is screwed into the corresponding locking hole (421) until the head of the fastener abuts against the base (5), so that the extension carrier (42) and the base (5) are pressed together and fixed.

6. The external rotor motor without a plastic core tube according to claim 1, characterized in that, The rotor assembly (3) also includes: The rotor plastic-coated part (32) is fixedly connected to the rotor shaft (31) at its center; Motor housing (33), which is embedded inside the rotor plastic coating (32) and located on the periphery of the rotor shaft (31); A permanent magnet (34) is fixedly installed on the inner circumference of the motor housing (33), and a magnetic air gap is defined between the permanent magnet (34) and the outer circumference of the stator core (1).

7. The external rotor motor without a plastic core tube according to claim 1, characterized in that: It also includes an electrical control board (6), which is fixedly installed on the stator rubber-coated part (4) and located between the base (5) and the stator core (1); a stator winding is wound on the stator core (1), and the stator winding is electrically connected to the electrical control board (6).

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