Oil-impregnated bearing assembly and outer rotor fan

Abstract

The utility model relates to oil bearing technology field, and it contains: wheel hub, bearing seat, oil bearing, shaft and buckle. The wheel hub side extension is provided with the convex part, and the bearing seat is assembled to the side close to the convex part, and the bearing seat is provided with the wear -resisting spare in, the oil bearing is assembled in the bearing seat, the shaft one end is fixed on the convex part, the other end is worn in the oil bearing, and the wear -resisting spare is abutted, and the buckle is assembled to the opening end of bearing seat, and is buckled on the oil bearing, and the buckle is provided with the shaft hole of avoiding the shaft wear, and the oil bearing includes: bearing body and the first recess and the second recess that are provided with one or more respectively and are communicated and set up in the bearing body periphery, two recesses are communicated and set up with buckle, and gas flows through the buckle after from recess and is discharged through the shaft hole. Adopt the above technical scheme, have the advantage that reduce lubricating oil overflow or volatilization, and can block the invasion of foreign matter, reduce the friction coefficient, improve the service life.

Description

Technical Field

[0001] This utility model relates to the field of oil-impregnated bearing technology, specifically to an oil-impregnated bearing assembly and an external rotor fan. Background Technology

[0002] Sintered oil-impregnated bearings are widely used in external rotor motors or fans, with their core advantage being their self-lubricating properties. However, the evaporation of lubricating oil and the intrusion of foreign matter have long constrained their reliability and lifespan. Current lubrication mechanisms rely on porous structures, with bearings impregnated with low-viscosity lubricating oil. During operation, frictional heat and internal pressure differences cause the lubricating oil to seep to the inner surface of the bearing, forming a pressure oil film between the inner surface and the outer surface of the shaft. However, low-viscosity lubricating oil is prone to evaporation, especially under high-temperature or high-speed conditions. Moreover, traditional bearing structures are open and lack effective sealing designs, allowing dust, microparticles, and other foreign matter to easily enter the bearing clearances, accelerating lubricating oil contamination and friction pair wear. After lubricating oil evaporation or contamination, the pressure oil film cannot be maintained, the coefficient of friction increases sharply, leading to abnormal bearing wear and reducing bearing lifespan. Utility Model Content

[0003] The purpose of this utility model is to address the defects and shortcomings of the existing technology by providing an oil-impregnated bearing assembly and an external rotor fan, which has the advantages of reducing lubricating oil spillage or evaporation, preventing foreign matter intrusion, reducing the coefficient of friction, and improving service life.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is: an oil-impregnated bearing assembly, comprising:

[0005] The wheel hub has a protrusion extending from one side;

[0006] A bearing housing is assembled on one side near the protrusion. A cavity is provided inside the bearing housing, and a wear-resistant part is provided at the bottom of the cavity.

[0007] An oil-impregnated bearing is assembled inside the cavity;

[0008] A shaft, one end fixed to the protrusion, the other end passing through the oil-impregnated bearing and abutting against the wear-resistant component; and

[0009] A fastener is assembled at the open end of the bearing housing and fastens to the oil-impregnated bearing. The fastener is provided with a shaft hole to avoid the shaft center passing through.

[0010] The oil-impregnated bearing includes: a bearing body, one or more first grooves disposed on the side of the bearing body opposite to the fastener, and one or more second grooves disposed on the periphery of the bearing body and communicating with the first grooves and the fastener for venting.

[0011] The present invention further provides that the second groove includes: a first groove symmetrically disposed on the periphery of the bearing body, and a second groove symmetrically disposed on the periphery of the bearing body.

[0012] The present invention further provides that the fastener includes: a first fastener body, a first positioning fastener symmetrically extending from the edge of the first fastener body facing the oil-impregnated bearing and used for inserting into the first groove, and a third groove symmetrically arranged from the edge of the first fastener body facing the oil-impregnated bearing and communicating with the second groove for venting.

[0013] The present invention further provides that the fastener includes: a second fastener body, a second positioning fastener symmetrically disposed on the inner wall of the second fastener body for inserting into the first groove, and a third groove symmetrically disposed on the side of the second fastener body facing the oil-impregnated bearing and communicating with the second groove for venting.

[0014] The present invention further provides that the fastener includes: a first fastener body, having one or more protrusions disposed on the periphery of the first fastener body, a first positioning buckle symmetrically extending on the edge of the first fastener body facing the oil-impregnated bearing for insertion into the first groove, and a third groove symmetrically disposed on the side of the first fastener body facing the oil-impregnated bearing and communicating with the second groove for venting.

[0015] The present invention further provides that the fastener includes: a second fastener body, having one or more protrusions disposed on the periphery of the fastener body, a second positioning buckle symmetrically disposed on the inner wall of the second fastener body for inserting into the first groove, and a third groove symmetrically disposed on the side of the second fastener body facing the oil-impregnated bearing and communicating with the second groove for venting.

[0016] The present invention is further provided that the first groove, the second groove and the third groove are connected to form an exhaust channel.

[0017] The present invention further provides that a first gap is provided between the shaft hole of the fastener and the surface of the shaft; and a second gap is provided between the side of the fastener facing the hub and the protrusion.

[0018] The present invention further includes, in that the oil-impregnated bearing assembly, a retaining ring sleeved on the side of the shaft near the wear-resistant part.

[0019] To achieve the above objectives, another technical solution adopted by this utility model is: an external rotor fan, comprising a fan body and an oil-impregnated bearing assembly as described above, assembled inside the fan body.

[0020] The beneficial effects of this utility model after adopting the above technical solution are as follows: In this utility model, by providing an oil-impregnated bearing and a fastener, wherein the oil-impregnated bearing is connected to a first groove and a second groove, and the fastener is fastened to the second groove of the oil-impregnated bearing and is connected to the second groove, when the rotor rotates, the end face of the shaft rubs against the wear-resistant parts and generates heat. This heat causes the gas temperature in the space at the bottom of the bearing housing to rise and expand. Because the outer wall of the oil-impregnated bearing has grooves, the expanded gas is discharged directly through the grooves to the fastener, avoiding the risk of the expanded gas carrying lubricating oil to overflow or evaporate through the shaft surface. At the same time, because a stepped structure is provided between the surface of the fastener and the protrusion of the hub, it can prevent the intrusion of external dust and foreign objects. Therefore, compared with the earlier oil-impregnated bearing assembly, it has the advantages of reducing lubricating oil overflow or evaporation, preventing the intrusion of foreign objects, reducing the coefficient of friction, and improving service life. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is an exploded view of the structure of Embodiment 1;

[0023] Figure 2 This is another exploded view of the structure in Embodiment 1;

[0024] Figure 3 This is a schematic cross-sectional view of section AA in Example 1;

[0025] Figure 4 This is an exploded view of the structure in Example 2;

[0026] Figure 5 This is a schematic cross-sectional view of section BB in Example 2;

[0027] Figure 6 This is an exploded view of the structure in Example 3;

[0028] Figure 7 This is a schematic cross-sectional view of the CC section in Embodiment 3;

[0029] Figure 8 This is an exploded view of the structure in Example 4;

[0030] Figure 9 This is a schematic cross-sectional view of the DD section in Embodiment 4;

[0031] Figure 10This is a schematic diagram of the external rotor fan structure adopted in Embodiment 3;

[0032] Figure 11 This is a schematic diagram of the external rotor fan structure adopted in Embodiment 4.

[0033] Explanation of reference numerals in the attached drawings: 100, hub; 110, protrusion; 111, second annular groove; 200, bearing seat; 210, cavity; 220, wear-resistant part; 300, oil-impregnated bearing; 310, bearing body; 320, first groove; 330, second groove; 331, groove one; 332, groove two; 400, shaft; 500, fastener; 510, shaft hole; 520, first fastener body; 521, first annular groove; 522, first annular platform; 530, second fastener body; 531, third annular groove; 532, second annular platform; 540, first positioning fastener; 550, second positioning fastener; 560, third groove; 570, boss; 600, fastening ring; 700, fan body. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings.

[0035] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive element, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0036] Example 1

[0037] This embodiment relates to an oil-impregnated bearing assembly, as shown in the reference... Figures 1-3 It includes: hub 100, bearing housing 200, oil-impregnated bearing 300, shaft 400 and fastener 500.

[0038] The hub 100 has a protrusion 110 extending from one side to fix one end of the shaft 400, forming a rigid connection between the shaft 400 and the hub 100 to ensure stable transmission of rotational power. Specifically, the protrusion 110 has a mounting groove (not shown) in the middle for fixing the shaft 400. The bearing housing 200 is located near the protrusion 110 and is integrally formed. The bearing housing 200 has a cavity 210, which provides installation space for the oil-impregnated bearing 300 and restricts the axial displacement of the bearing. A wear-resistant component 220 is built into the bottom of the cavity 210, abutting against the end face of the shaft 400, bearing the axial force of the shaft 400, reducing direct wear, and extending the component's lifespan. The bearing housing 200 serves as the mounting carrier for the oil-impregnated bearing 300 and the wear-resistant component 220, bearing the radial and axial loads during the rotation of the shaft 400. Furthermore, the inner bottom of the bearing housing 200 has an inwardly recessed portion (not shown), which allows the wear-resistant part 220 to be assembled, preventing the wear-resistant part 220 from shifting when the shaft 400 rotates into contact with it. One end of the shaft 400 is fixedly connected to the protrusion 110, and the other end passes through the oil-impregnated bearing 300 and abuts against the wear-resistant part 220 at the bottom of the bearing housing 200. As a rotating core component, the shaft 400 connects to the hub 100 or external loads (such as gears, impellers, etc.), transmits torque, and achieves rotational guidance through the inner hole of the oil-impregnated bearing 300, ensuring rotational accuracy.

[0039] The oil-impregnated bearing 300 is assembled within the cavity 210. The oil-impregnated bearing 300 and the bearing housing 200 have a clearance fit. The oil-impregnated bearing 300 is a porous structure component made of powder metallurgy. The clearance fit overcomes external pressure and prevents it from affecting the air permeability of its internal porous structure, thus affecting the flow of lubricating oil inside the oil-impregnated bearing 300. When the flow of lubricating oil inside the oil-impregnated bearing 300 is obstructed, it can lead to lubrication failure of the bearing, thereby affecting its service life. The internal pores of the oil-impregnated bearing 300 store lubricating oil, which is released through capillary action during rotation, forming a pressure oil film between the shaft 400 and the bearing 300, preventing direct contact and reducing friction and wear. Furthermore, it ensures the dimensional accuracy of the inner wall of the bearing housing 200 and the precise assembly of the oil-impregnated bearing 300, allowing for a suitable reduction in the clearance between the assembled oil-impregnated bearing 300 and the inner wall of the bearing housing 200, thereby improving rotational accuracy.

[0040] Reference Figures 1-3 and Figure 6Furthermore, the oil-impregnated bearing 300 includes a bearing body 310, a first groove 320, and a second groove 330. Four first grooves 320 are provided, spaced apart in pairs on the side of the bearing body 310 facing away from the fastener 500. During assembly or operation, air or vapor generated at the bottom of the bearing is evenly discharged to the periphery through the first grooves 320. Four second grooves 330 are provided, spaced apart in pairs on the periphery of the bearing body 310, and are connected to both the second grooves 330 and the fastener 500. The second grooves 330 on the periphery of the bearing connect to the fastener 500, forming an exhaust channel, allowing gas to flow from the first groove 320 through the second groove 330 and then discharge from the shaft hole 510 of the fastener 500. This prevents internal pressure buildup that could cause lubricating oil to overflow from the shaft hole 510 or the bearing clearance, while also reducing lubricating oil evaporation due to high pressure. In other embodiments, two, three, or more first grooves 320 and second grooves 330 may be provided; the number of both is not limited here.

[0041] Furthermore, the second groove 330 includes groove one 331 and groove two 332. Grooves one 331 and groove two 332 are symmetrically distributed around the bearing body 310, allowing air inside the bearing to be discharged simultaneously from multiple symmetrical directions, avoiding uneven air pressure distribution caused by unilateral exhaust. In other embodiments, groove one 331 and groove two 332 may also adopt other distribution methods.

[0042] The fastener 500 engages with the open end of the bearing housing 200, and it presses the oil-impregnated bearing 300 tightly into the cavity 210 of the bearing housing 200, preventing the oil-impregnated bearing 300 from loosening. Specifically, the fastener 500 and the bearing housing 200 are interference-fitted. The fastener 500 is provided with a shaft hole 510 for the shaft 400 to pass through, and the fastener 500 communicates and engages with the second groove 330 to smoothly discharge gas and reduce lubricating oil leakage from the shaft hole 510. At the same time, it engages with the protrusion 110 of the hub 100 to prevent foreign objects from entering through the shaft hole 510. Specifically, the outer circumferential surface of the fastener 500 is wider at the top and narrower at the bottom, which facilitates the smooth insertion and fastening of the fastener 500 from the open end of the bearing housing 200. When the upper surface of the fastener 500 is aligned with the edge of the opening of the bearing housing 200, the fastening state is achieved. Furthermore, the outer circumference of the 500 fastener is a full circumferential structure, which facilitates quick fastening, is suitable for smaller bearings, is easy to process, and has reliable fastening.

[0043] Reference Figures 1-2Furthermore, the fastener 500 includes a first fastener body 520, a first positioning fastener 540, and a third groove 560. The fastener 500 is suitable for bearings with smaller dimensions. The first positioning fastener 540 extends symmetrically from the edge of the first fastener body 520 facing the oil-impregnated bearing 300, facilitating insertion into the first groove 331. The first groove 331, as a symmetrical groove on the circumference of the bearing body 310, forms a concave-convex fit with the first positioning fastener 540, further enhancing the circumferential positioning of the oil-impregnated bearing 300. The third groove 560 is symmetrically located on the side of the first fastener body 520 facing the oil-impregnated bearing 300 and communicates with the second groove 332, thereby allowing gas to be expelled through the shaft 400. Therefore, when the oil-impregnated bearing 300 generates heat due to friction or air pressure during assembly, the gas can flow into the third groove 560 through the second groove 332 and then exit from the shaft hole 510 of the fastener 500. This prevents excessive pressure buildup that could lead to a large pressure difference between the inside and outside of the bearing, thus accelerating the extrusion or evaporation of lubricating oil within the oil-impregnated bearing 300. The exhaust channel ensures a dynamic balance of internal and external air pressure. Specifically, the first positioning buckle 540 and the third groove 560 are arranged in a cross shape. In other embodiments, the first positioning buckle 540 and the third groove 560 may also be arranged in other ways. In other embodiments, three or more of the first positioning buckle 540 and the third groove 560 may also be provided.

[0044] Furthermore, the first groove 320, the second groove 330, and the third groove 560 are connected to form an exhaust channel, which facilitates the smooth discharge of gas, maintains the dynamic balance of internal and external air pressure, and prevents lubricating oil from being sprayed out with the gas.

[0045] Reference Figure 3 In this embodiment, a gap is provided between the shaft hole 510 of the fastener 500 and the surface of the shaft 400. This gap is the first gap portion, which can prevent lubricating oil from overflowing, reduce lubricating oil loss, and thus extend the bearing life. A second gap portion is provided between the side of the fastener 500 facing the hub 100 and the protrusion 110 to prevent foreign objects from entering. Further, the first fastener body 520 is provided with an inwardly recessed first annular groove 521 on the side facing the hub 100. The shaft 400 is disposed through the middle of the first annular groove 521. A first annular platform 522 extends from the middle of the first annular groove 521 and extends around the edge of the shaft 400. Further, the protrusion 110 is provided with an inwardly recessed second annular groove 111 on the side facing the fastener 500. After the shaft 400 is inserted into the oil-impregnated bearing 300, the second annular groove 111 is assembled in the first annular groove 521, and there is a gap between the second annular groove 111 and the first annular groove 521 to form a labyrinth seal structure. Furthermore, the second annular groove 111 and the second annular platform 532 form a second gap, which can prevent external dust and other foreign objects from entering the gap between the bearing and the bearing housing 200.

[0046] This embodiment also relates to an external rotor fan, see reference. Figures 10-11 The fan body 700 includes a fan body 700 and an oil-impregnated bearing assembly disposed within the fan body 700 as described above. Specifically, the fan body 700 further includes a circuit control board, a drive unit, a stator assembly, and a rotor assembly. In other embodiments, the oil-impregnated bearing assembly can also be applied to other external rotor devices such as external rotor motors.

[0047] Example 2

[0048] Reference Figures 4-5 This embodiment is basically the same as Embodiment 1, except that the fastener 500 is suitable for bearings with larger dimensions. The fastener 500 includes a second fastener body 530 and a second positioning fastener 550. The second positioning fastener 550 is symmetrically arranged on the inner wall of the second fastener body 530 and is used to insert into the groove 331 to form a rigid fit for the large-sized bearing, effectively limiting the circumferential displacement of the bearing and avoiding assembly misalignment or radial shaking during rotation due to its large size. Specifically, a third annular groove 531 is provided on the side of the second fastener body 530 facing the oil-impregnated bearing 300, and the second positioning fastener 550 is symmetrically arranged on the inner wall of the third annular groove 531. The third annular groove 531 is fastened and positioned on the oil-impregnated bearing 300. Further, a second annular platform 532 is extended from the middle of the side of the second fastener body 530 facing the hub 100 and extends around the edge of the shaft 400. After the shaft 400 is inserted into the oil-impregnated bearing 300, the second annular groove 111 is assembled on the second buckle body 530, and there is a gap between the second annular groove 111 and the second buckle body 530. Thus, the second annular groove 111 and the second annular platform 532 form a second gap, which can prevent external dust and other foreign objects from entering the gap between the bearing and the bearing seat 200.

[0049] Furthermore, the oil-impregnated bearing assembly also includes a retaining ring 600. The retaining ring 600 is sleeved on the side of the shaft 400 near the wear-resistant part 220, restricting the axial movement of the shaft 400 toward the wear-resistant part 220.

[0050] Example 3

[0051] Reference Figures 6-7 This embodiment is basically the same as Embodiment 1, except that the fastener 500 is suitable for bearings with a small axial height. The fastener 500 includes multiple bosses 570, spaced apart on the periphery of the first fastener body 520, for engaging with the open end of the bearing housing 200 to prevent loosening, strengthen the fixation, and achieve axial positioning of the oil-impregnated bearing 300. An annular retaining platform (not shown) is provided on the inner wall of the open end of the bearing housing 200 for engaging and fastening with the bosses 570, restricting the axial rotation and axial disengagement of the fastener 500.

[0052] Example 4

[0053] Reference Figures 8-9This embodiment is basically the same as Embodiment 1, except that the fastener 500 is suitable for bearings with a large axial height. The fastener 500 includes a second fastener body 530, a boss 570, and a second positioning buckle 550. By extending the axial length of the second fastener body 530, it covers a deeper area of ​​the opening end of the bearing housing 200, ensuring effective clamping of bearings with large axial dimensions. Multiple bosses 570 are provided and spaced apart on the periphery of the fastener body to engage with the opening end of the bearing housing 200, preventing loosening, strengthening the fixation, and achieving axial positioning of the oil-impregnated bearing 300. An annular retaining platform is provided on the inner wall of the opening end of the bearing housing 200 to engage and fasten with the bosses 570, restricting the axial rotation and axial dislodgement of the fastener 500. The second positioning buckle 550 is symmetrically arranged on the inner wall of the fastener body and is used to insert into the groove 331 to form a rigid fit for the large-sized bearing, effectively restricting the circumferential displacement of the bearing and avoiding assembly misalignment or radial wobbling during rotation due to the large size. Specifically, a third annular groove 531 is provided on the side of the second buckle 530 facing the oil-impregnated bearing 300, and second positioning buckles 550 are symmetrically provided on the inner wall of the third annular groove 531. The third annular groove 531 is engaged and positioned on the oil-impregnated bearing 300. Further, a second annular platform 532 is provided extending from the middle of the side of the second buckle 530 facing the hub 100, and extends around the edge of the shaft 400. When the shaft 400 is inserted into the oil-impregnated bearing 300, the second annular groove 111 is assembled on the second buckle 530, and a gap is provided between the second annular groove 111 and the second buckle 530. Thus, the second annular groove 111 and the second annular platform 532 form a second gap, which can prevent external dust and other foreign objects from entering the gap between the bearing and the bearing housing 200.

[0054] Furthermore, the oil-impregnated bearing assembly also includes a retaining ring 600. The retaining ring 600 is sleeved on the side of the shaft 400 near the wear-resistant part 220, restricting the axial movement of the shaft 400 toward the wear-resistant part 220.

[0055] The above is only used to illustrate the technical solution of this utility model and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of this utility model, as long as they do not depart from the spirit and scope of the technical solution of this utility model, should be covered within the scope of the claims of this utility model.

Claims

1. An oil-impregnated bearing assembly, characterized in that, include: A wheel hub (100) has a protrusion (110) extending from one side; A bearing housing (200) is assembled on the side near the protrusion (110). A cavity (210) is provided inside the bearing housing (200), and a wear-resistant part (220) is provided at the bottom of the cavity (210). An oil-impregnated bearing (300) is assembled inside the cavity (210); The shaft (400) is fixed at one end to the protrusion (110) and the other end passes through the oil-impregnated bearing (300) and abuts against the wear-resistant part (220); as well as A fastener (500) is assembled at the open end of the bearing housing (200) and fastened to the oil-impregnated bearing (300). The fastener (500) is provided with a shaft hole (510) to avoid the shaft (400) from passing through. The oil-impregnated bearing (300) includes: a bearing body (310), one or more first grooves (320) disposed on the side of the bearing body (310) facing away from the fastener (500), and one or more second grooves (330) disposed on the periphery of the bearing body (310) and communicating with the first groove (320) and the fastener (500) for venting.

2. The oil-impregnated bearing assembly according to claim 1, characterized in that, The second groove (330) includes: a first groove (331) symmetrically disposed on the periphery of the bearing body (310), and a second groove (332) symmetrically disposed on the periphery of the bearing body (310).

3. The oil-impregnated bearing assembly according to claim 2, characterized in that, The fastener (500) includes: a first fastener body (520), a first positioning fastener (540) symmetrically extending from the edge of the first fastener body (520) facing the oil-impregnated bearing (300) for insertion into the first groove (331), and a third groove (560) symmetrically arranged from the edge of the first fastener body (520) facing the oil-impregnated bearing (300) and communicating with the second groove (332) for venting.

4. The oil-impregnated bearing assembly according to claim 2, characterized in that, The fastener (500) includes: a second fastener body (530), a second positioning fastener (550) symmetrically disposed on the inner wall of the second fastener body (530) for inserting into the first groove (331), and a third groove (560) symmetrically disposed on the side of the second fastener body (530) facing the oil-impregnated bearing (300) and communicating with the second groove (332) for venting.

5. The oil-impregnated bearing assembly according to claim 2, characterized in that, The fastener (500) includes: a first fastener body (520), one or more bosses (570) provided on the periphery of the first fastener body (520), a first positioning buckle (540) symmetrically extended on the edge of the first fastener body (520) facing the oil-impregnated bearing (300) for insertion into the first groove (331), and a third groove (560) symmetrically provided on the side of the first fastener body (520) facing the oil-impregnated bearing (300) and communicating with the second groove (332) for venting.

6. The oil-impregnated bearing assembly according to claim 2, characterized in that, The fastener (500) includes: a second fastener body (530), one or more bosses (570) provided on the periphery of the fastener body, a second positioning buckle (550) symmetrically arranged on the inner wall of the second fastener body (530) for insertion into the first groove (331), and a third groove (560) symmetrically arranged on the side of the second fastener body (530) facing the oil-impregnated bearing (300) and communicating with the second groove (332) for venting.

7. The oil-impregnated bearing assembly according to any one of claims 3-6, characterized in that, The first groove (320), the second groove (330) and the third groove (560) are connected to form an exhaust channel.

8. The oil-impregnated bearing assembly according to any one of claims 3-6, characterized in that, A first gap is provided between the shaft hole (510) of the fastener (500) and the surface of the shaft (400); a second gap is provided between the side of the fastener (500) facing the hub (100) and the protrusion (110).

9. The oil-impregnated bearing assembly according to claim 4 or 6, characterized in that, The oil-impregnated bearing assembly further includes a retaining ring (600) sleeved on the side of the shaft (400) near the wear-resistant part (220).

10. An external rotor fan, characterized in that, It includes a fan body (700) and an oil-impregnated bearing assembly as described in any one of claims 1-9, which is assembled within the fan body (700).

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