Self-cooling air suspension fan and cooling method thereof

Abstract

The present invention discloses a self-cooling air suspension fan and a cooling method thereof, belonging to the field of fan cooling, comprising a fan housing, a stator and a rotor, wherein the rotor is connected to the main impeller via a first locking rod, an end shell is connected to the fan housing, an air inlet aligned with the main impeller is provided on the end shell, and an end cover is fixed to the other end of the fan housing. The present invention also includes an air cooling structure, which comprises an active stator-rotor air cooling unit and a passive bearing cooling unit, wherein the active stator-rotor air cooling unit comprises an induced draft impeller fixed to the end of the rotor away from the main impeller via a second locking rod, and a stator-rotor cooling air duct; the passive bearing cooling unit comprises an air cooling return duct for connecting the air inlet and the interior of the fan housing, and a bearing cooling air duct connected to the air cooling return duct. By adopting the above-mentioned self-cooling air suspension fan and a cooling method thereof, a combination of active and passive air cooling is adopted to rapidly cool the interior of the fan, thereby improving the cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of fan cooling, and in particular to a self-cooling air suspension fan and a cooling method thereof. Background Art

[0002] An air bearing fan is a highly efficient and energy-saving fan that utilizes air bearing technology. The core technology of air bearings is the air bearing. Air bearings use compressed air as a lubricant, forming a thin air film between the rotor and stator, enabling the rotor to rotate at high speed without contact. These bearings offer advantages such as high efficiency, energy savings, low noise, long life, and maintenance-free operation. They are becoming increasingly important equipment in modern industry and the environmental protection field.

[0003] The existing air suspension fan heat dissipation structure is as follows:

[0004] CN202121081986.1 discloses an air suspension fan with a heat dissipation structure, including an air suspension fan assembly, a cooling mechanism and a pin mechanism, wherein the cooling mechanism is arranged on one side of the outside of the air suspension fan assembly; the pin mechanism is fixed inside the air suspension fan assembly; and the filtering mechanism is installed on the other side of the outside of the air suspension fan assembly. Compared with the existing ordinary air suspension fans, the air suspension fan with a heat dissipation structure has multiple copper sheets that absorb the heat generated when the air suspension fan assembly is in operation. The cover of the liquid storage tank is opened to add coolant, and the water pump pumps the coolant in the liquid storage tank into the return pipe. The return pipe cools the copper sheets, which can significantly cool the air suspension fan, so that the air suspension fan has an active heat dissipation function. When the temperature of the air suspension fan is too high, the heat of the air suspension fan can be dissipated in time.

[0005] CN202420395201.5 discloses a cooling structure for an air suspension fan, which includes a base box, an electric control cabinet is installed inside the base box, a fan body is installed inside the base box on one side of the electric control cabinet, the output end of the fan body is connected to an exhaust pipe, an air cooling mechanism is provided on the base box, and a liquid cooling mechanism is provided just below the fan body. This utility model overcomes the shortcomings of the prior art, and by starting a water pump located inside the storage chamber, the coolant inside the storage chamber can be transported along the cooling water output pipe to the inside of a water cooling head, the water cooling head is attached to the fan body, and the heat is absorbed by the coolant flowing through the water cooling head, and at the same time, the coolant that absorbs the heat can enter the temporary storage chamber along the cooling water return pipe, and the liquid inside the temporary storage chamber can flow back to the storage chamber with the help of a heat dissipation pipe, and the coolant flowing through the heat dissipation pipe can dissipate heat and cool down the outside with the help of a heat sink.

[0006] It can be seen that the cooling structure of existing air suspension fans is mostly liquid cooling, which has the disadvantages of occupying a large space and not completely cooling the inside of the fan. Summary of the Invention

[0007] The purpose of the present invention is to provide a self-cooling air suspension fan and a cooling method thereof to solve the above technical problems.

[0008] To achieve the above-mentioned objectives, the present invention provides a self-cooling air suspension fan, comprising a fan housing, a stator, and a rotor, arranged in sequence from the outside to the inside. The rotor is connected to the main impeller via a first locking rod. An end shell is connected to the end of the fan housing corresponding to the main impeller. The end shell is provided with an air inlet aligned with the main impeller. An end cover is fixed to the other end of the fan housing. The present invention also includes an air cooling structure, which includes an active stator and rotor air cooling unit and a passive bearing cooling unit. The active stator and rotor air cooling unit includes an induced draft impeller fixed to the end of the rotor away from the main impeller via a second locking rod, and a stator and rotor cooling air duct.

[0009] The passive bearing cooling unit includes an air-cooling return air pipe for connecting the air inlet and the interior of the fan housing, and a bearing cooling air duct connected to the air-cooling return air pipe.

[0010] Preferably, the stator and rotor cooling air duct includes a first radial air inlet hole opened on the side wall of the fan housing, a first cooling air section surrounded by the outer wall of the stator and the inner wall of the fan housing, a second cooling air section surrounded by the inner wall of the stator and the outer wall of the rotor, and a first axial air outlet hole opened on the end cover.

[0011] Preferably, an exhaust cover is also provided on the outside of the end cover, and the stator rotor cooling air duct also includes a first radial air outlet hole opened on the side wall of the exhaust cover, and the first radial air inlet hole, the first cooling air section, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole are connected in sequence.

[0012] Preferably, the outer cover of the main impeller is provided with a fairing, and the main impeller is rotatably arranged on the main mounting plate through the main bearing and the main balance plate in sequence, and the main mounting plate is fixed on the fan housing;

[0013] The left and right ends of the rotor are rotatably connected to the fan housing via the left and right bearings respectively;

[0014] The bearing cooling air duct includes a first bearing cooling air section, a second bearing cooling air section and a third bearing cooling air section for cooling the main bearing, the left end bearing and the right end bearing respectively. The first bearing cooling air section is connected to the air cooling return air duct, and the second bearing cooling air section and the third bearing cooling air section are both connected to the stator and rotor cooling air duct.

[0015] Preferably, the first bearing cooling air section includes a first axial air inlet hole opened in the center of the fairing, a second axial air inlet hole opened on the main impeller, a second radial air inlet hole opened on the main impeller, and a cooling cavity surrounded by the main bearing, the fan housing and the main mounting plate;

[0016] The air inlet is in circular communication with the first axial air inlet hole, the second axial air inlet hole, the second radial air inlet hole, the cooling cavity and the air-cooling return air pipe.

[0017] Preferably, the second bearing cooling air section includes a first axial air inlet hole, a third axial air inlet hole provided on the first locking rod, a fourth axial air inlet hole provided at one end of the rotor, and second radial air outlet holes provided on the left and right side walls of the rotor;

[0018] The air inlet is connected in sequence with the first axial air inlet hole, the second axial air inlet hole, the third axial air inlet hole, the fourth axial air inlet hole, the second radial air outlet hole, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole.

[0019] Preferably, a sealing cap is provided at the center of the exhaust housing;

[0020] The third bearing cooling air section includes a fifth axial air inlet hole opened in the center of the sealing cap, a sixth axial air inlet hole opened on the second locking rod, and a seventh axial air inlet hole opened at the other end of the rotor. The fifth axial air inlet hole, the sixth axial air inlet hole, the seventh axial air inlet hole, the second radial air outlet hole, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole are connected in sequence.

[0021] A cooling method for a self-cooling air suspension fan, including a stator and rotor cooling method and a bearing cooling method;

[0022] The stator and rotor cooling method is as follows: the rotor drives the induced draft impeller to rotate, thereby generating negative pressure inside the fan housing. External cold air enters the fan housing through the first radial air inlet, then passes through the first cooling air section, the second cooling air section, the first axial air outlet, and finally is discharged from the fan housing through the first radial air outlet. When the cold air flows through the second cooling air section, the stator and rotor are cooled simultaneously.

[0023] The bearing cooling method includes a main bearing cooling method, a left-end bearing cooling method and a right-end bearing cooling method. The main bearing cooling method is as follows: the rotor drives the main impeller to rotate, so that the static pressure of the air inlet is lower than the ambient static pressure. Since the air-cooling return air duct connects the cooling cavity and the air inlet, the pressure of the cooling cavity is lower than the ambient static pressure. The total pressure on the windward side of the main impeller is the sum of the dynamic pressure and the static pressure. Therefore, the total pressure on the windward side of the main impeller is higher than the pressure of the cooling cavity, that is, the total pressure of the first axial air inlet hole on the fairing is higher than the pressure of the cooling cavity, thereby generating a pressure difference. Under the action of the pressure difference, external cold air is discharged from the air inlet, the first axial air inlet hole, the second axial air inlet hole, the second radial air inlet hole, the cooling cavity and the air-cooling return air duct, and the cold air cools the main bearing after entering the cooling cavity;

[0024] The cooling method for the left-end bearing and the right-end bearing is as follows: during the rotation of the rotor, the gas inside the rotor is discharged from the second radial air outlet under the action of centrifugal force, resulting in a negative pressure state inside the rotor, and external cold air enters through the air inlet and the fifth axial air inlet respectively, among which the cold air entering from the air inlet is discharged through the first axial air inlet, the second axial air inlet, the third axial air inlet, the fourth axial air inlet, the second radial air outlet, the second cooling air section, the first axial air outlet and the first radial air outlet in sequence, and cools the left-end bearing after entering the fan housing through the second radial air outlet; at the same time, the cold air entering from the fifth axial air inlet is discharged through the sixth axial air inlet, the seventh axial air inlet, the second radial air outlet, the second cooling air section, the first axial air outlet and the first radial air outlet in sequence, and cools the right-end bearing after entering the fan housing through the second radial air outlet.

[0025] Therefore, the present invention adopts the above-mentioned self-cooling air suspension fan and cooling method thereof, which has the following beneficial effects:

[0026] 1. Efficient cooling: Stator and rotor cooling: Through the design of the induced draft impeller and cooling air duct, cold air can effectively flow through the stator and rotor to take away heat. When the rotor drives the induced draft impeller to rotate, negative pressure is formed in the fan housing. External cold air is sucked in and discharged through multiple cooling air ducts, ensuring that the stator and rotor are always kept at a low temperature, improving operating efficiency and stability.

[0027] Bearing cooling: The main bearing, left end bearing and right end bearing are cooled through independent cooling air ducts, which effectively reduces the bearing temperature and extends the bearing life.

[0028] 2. Compact and integrated structure: The cooling structure is integrated with the fan body, reducing the need for additional cooling equipment, space occupation and installation complexity. For example, the fairing, induced draft impeller, cooling duct and other components are cleverly combined inside the fan, achieving a compact integrated design.

[0029] 3. No additional power consumption: The cooling system relies on the operation of the fan itself to drive the air flow, without the need for additional power source or pumping equipment, saving energy consumption;

[0030] 4. High reliability: Since the cooling system is closely integrated with the fan body and adopts the principles of natural ventilation and negative pressure, the wear and failure rate of mechanical components are reduced, thereby reducing maintenance costs and frequency;

[0031] 5. Strong environmental adaptability: It maintains good cooling effect under different environmental conditions and is suitable for a variety of harsh environments such as high temperature and high humidity, especially for flammable and explosive places, avoiding the safety hazards brought by the use of liquid cooling;

[0032] 6. Low noise: The design of the cooling air duct and the induced draft impeller has been optimized to make the airflow smoother, reduce air turbulence and noise generation. This low noise design has obvious advantages, especially in residential areas or noise-sensitive environments.

[0033] In summary, the present invention not only has efficient cooling performance, but also significantly improves the overall performance and application range of the fan through the advantages of compact integrated design, energy saving effect, high reliability and low noise, ensuring long-term stable operation of the fan.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an axial cross-sectional view of a self-cooling air suspension fan according to the present invention.

[0036] Reference numerals

[0037] 1. Air inlet; 2. Fairing; 3. Main impeller; 4. End shell; 5. Main mounting plate; 6. Stator; 7. Fan housing; 8. First radial air inlet; 9. End cover; 10. First radial air outlet; 11. Exhaust cover; 12. Sealing cap; 13. Fifth axial air inlet; 14. Second locking rod; 15. Sixth axial air inlet; 16. Induced draft impeller; 17. First axial air outlet; 18. Second radial air outlet; 19. Left end bearing; 20. Main bearing; 21. Air cooling return air duct; 22. Main balancing plate; 23. Third axial air inlet; 24. First locking rod; 25. First axial air inlet; 26. Second cooling air section; 27. First cooling air section; 28. Right end bearing; 29. ​​Second axial air inlet. DETAILED DESCRIPTION

[0038] In order to make the purposes, technical solutions and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0039] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0040] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, a self-cooling air suspension fan includes a fan casing 7, a stator 6 and a rotor arranged in sequence from the outside to the inside, the rotor is connected to the main impeller 3 via a first locking rod 24, and an end shell 4 is connected to the fan casing 7 and one end corresponding to the main impeller 3, and an air inlet 1 aligned with the main impeller 3 is opened on the end shell 4, and an end cover 9 is fixed to the other end of the fan casing 7. The present invention also includes an air cooling structure, and the air cooling structure includes an active stator and rotor air cooling unit and a passive bearing cooling unit, wherein the active stator and rotor air cooling unit includes an induced draft impeller 16 fixed to the end of the rotor away from the main impeller 3 via a second locking rod 14, and a stator and rotor cooling air duct; the passive bearing cooling unit includes an air cooling return air duct 21 for connecting the air inlet 1 and the inside of the fan casing 7, and a bearing cooling air duct connected to the air cooling return air duct 21.

[0042] Specifically, the stator and rotor cooling air duct includes a first radial air inlet 8 provided on the side wall of the fan housing 7, a first cooling air segment 27 defined between the outer wall of the stator 6 and the inner wall of the fan housing 7, a second cooling air segment 26 defined between the inner wall of the stator 6 and the outer wall of the rotor, and a first axial air outlet 17 provided on the end cover 9. The end cover 9 is also covered by an exhaust shroud 11. The stator 6 and rotor cooling air duct also includes a first radial air outlet 10 provided on the side wall of the exhaust shroud 11. The first radial air inlet 8, the first cooling air segment 27, the second cooling air segment 26, the first axial air outlet 17, and the first radial air outlet 10 are sequentially connected.

[0043] The outer cover of the main impeller 3 is provided with a fairing 2, and the main impeller 3 is rotatably arranged on the main mounting plate 5 through the main bearing 20 and the main balance plate 22 in turn, and the main mounting plate 5 is fixed on the fan housing 7; the left and right ends of the rotor are rotatably connected to the fan housing 7 through the left end bearing 19 and the right end bearing 28 respectively; the bearing cooling air duct includes a first bearing cooling air section, a second bearing cooling air section and a third bearing cooling air section for cooling the main bearing 20, the left end bearing 19 and the right end bearing 28 respectively, wherein the first bearing cooling air section is connected to the air cooling return air duct 21, and the second bearing cooling air section and the third bearing cooling air section are both connected to the stator and rotor cooling air duct.

[0044] Among them, the first bearing cooling air section includes a first axial air inlet hole 25 opened in the center of the fairing 2, a second axial air inlet hole 29 opened on the main impeller 3, a second radial air inlet hole opened on the main impeller 3, and a cooling cavity surrounded by the main bearing 20, the fan housing 7 and the main mounting plate 5; the air inlet 1 is circularly connected with the first axial air inlet hole 25, the second axial air inlet hole 29, the second radial air inlet hole, the cooling cavity and the air-cooled return air pipe 21.

[0045] The second bearing cooling air section includes a first axial air inlet hole 25, a third axial air inlet hole 23 opened on the first locking rod 24, a fourth axial air inlet hole opened at one end of the rotor, and a second radial air outlet hole 18 opened on the left and right side walls of the rotor; the air inlet 1 is connected to the first axial air inlet hole 25, the second axial air inlet hole 29, the third axial air inlet hole 23, the fourth axial air inlet hole, the second radial air outlet hole 18, the second cooling air section 26, the first axial air outlet hole 17 and the first radial air outlet hole 10 in sequence.

[0046] A sealing cap 12 is provided at the center of the exhaust cover 11; the third bearing cooling air section includes a fifth axial air inlet 13 opened at the center of the sealing cap 12, a sixth axial air inlet 15 opened on the second locking rod 14, and a seventh axial air inlet opened at the other end of the rotor. The fifth axial air inlet 13, the sixth axial air inlet 15, the seventh axial air inlet, the second radial air outlet 18, the second cooling air section 26, the first axial air outlet 17 and the first radial air outlet 10 are connected in sequence.

[0047] A cooling method for a self-cooling air suspension fan, including a stator and rotor cooling method and a bearing cooling method;

[0048] The stator and rotor cooling method is as follows: the rotor drives the induced draft impeller 16 to rotate, thereby generating a negative pressure inside the fan housing 7. External cold air enters the fan housing 7 through the first radial air inlet 8, and then passes through the first cooling air section 27, the second cooling air section 26, the first axial air outlet 17, and then is discharged from the fan housing 7 through the first radial air outlet 10. When the cold air flows through the second cooling air section 26, the stator 6 and the rotor are cooled simultaneously.

[0049] The bearing cooling method includes a main bearing 20 cooling method, a left end bearing 19 cooling method and a right end bearing 28 cooling method. The main bearing 20 cooling method is as follows: the rotor drives the main impeller 3 to rotate, so that the static pressure of the air inlet is lower than the ambient static pressure. Since the air-cooling return air duct 21 connects the cooling cavity and the air inlet 1, the pressure of the cooling cavity is lower than the ambient static pressure. The total pressure on the windward side of the main impeller 3 is the sum of the dynamic pressure and the static pressure. Therefore, the total pressure on the windward side of the main impeller 3 is higher than the pressure of the cooling cavity, that is, the total pressure of the first axial air inlet hole 25 on the fairing 2 is higher than the pressure of the cooling cavity, thereby generating a pressure difference. Under the action of the pressure difference, the external cold air is discharged from the air inlet, the first axial air inlet hole 25, the second axial air inlet hole 29, the second radial air inlet hole, the cooling cavity and the air-cooling return air duct 21, and the cold air cools the main bearing 20 after entering the cooling cavity.

[0050] The cooling method of the left end bearing 19 and the right end bearing 28 is as follows: during the rotation of the rotor, the gas inside the rotor is discharged from the second radial air outlet 18 under the action of centrifugal force, resulting in a negative pressure state inside the rotor, and the external cold air enters through the air inlet 1 and the fifth axial air inlet 13 respectively, wherein the cold air entering from the air inlet 1 passes through the first axial air inlet 25, the second axial air inlet 29, the third axial air inlet 23, the fourth axial air inlet, the second radial air outlet 18, the second cooling air section 26, the third axial air inlet 27, the fourth axial air inlet, the second radial air outlet 18, the second cooling air section 26, the fifth axial air inlet 13 ... The cold air is discharged through the first axial air outlet 17 and the first radial air outlet 10, and cools the left end bearing 19 after entering the inside of the fan housing 7 through the second radial air outlet 18; at the same time, the cold air entering through the fifth axial air inlet 13 is discharged through the sixth axial air inlet 15, the seventh axial air inlet, the second radial air outlet 18, the second cooling air section 26, the first axial air outlet 17 and the first radial air outlet 10 in sequence, and cools the right end bearing 28 after entering the inside of the fan housing 7 through the second radial air outlet 18.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A self-cooling air suspension fan comprising a fan housing, a stator, and a rotor, arranged in sequence from the outside to the inside. The rotor is connected to a main impeller via a first locking rod. An end housing is connected to one end of the fan housing corresponding to the main impeller. The end housing has an air inlet aligned with the main impeller. An end cap is fixed to the other end of the fan housing. The fan housing is characterized by: The air cooling structure includes an active stator and rotor air cooling unit and a passive bearing cooling unit, wherein the active stator and rotor air cooling unit includes an induced draft impeller fixed to an end of the rotor away from the main impeller via a second locking rod and a stator and rotor cooling air duct; The passive bearing cooling unit includes an air-cooling return air duct for connecting the air inlet and the interior of the fan housing, and a bearing cooling air duct connected to the air-cooling return air duct. The bearing cooling air duct includes a first bearing cooling air section, a second bearing cooling air section, and a third bearing cooling air section for cooling the main bearing, the left end bearing, and the right end bearing, respectively. The first bearing cooling air section is connected to the air-cooling return air duct, and the second bearing cooling air section and the third bearing cooling air section are both connected to the stator and rotor cooling air duct. The outside of the end cover is also covered with an exhaust cover, and the center of the exhaust cover is provided with a sealing cap; The third bearing cooling air section includes a fifth axial air inlet hole opened at the center of the sealing cap, a sixth axial air inlet hole opened on the second locking rod, and a seventh axial air inlet hole opened at the other end of the rotor.

2. The self-cooling air suspension fan according to claim 1, characterized in that: The stator and rotor cooling air duct includes a first radial air inlet hole opened on the side wall of the fan housing, a first cooling air section surrounded by the outer wall of the stator and the inner wall of the fan housing, a second cooling air section surrounded by the inner wall of the stator and the outer wall of the rotor, and a first axial air outlet hole opened on the end cover.

3. The self-cooling air suspension fan according to claim 2, characterized in that: The stator rotor cooling air duct also includes a first radial air outlet hole opened on the side wall of the exhaust cover. The first radial air inlet hole, the first cooling air section, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole are connected in sequence.

4. The self-cooling air suspension fan according to claim 3, characterized in that: The outer cover of the main impeller is provided with a fairing. The main impeller is rotated and arranged on the main mounting plate through the main bearing and the main balance plate in sequence. The main mounting plate is fixed on the fan casing. The left and right ends of the rotor are rotatably connected to the fan housing via a left end bearing and a right end bearing respectively.

5. The self-cooling air suspension fan according to claim 4, characterized in that: The first bearing cooling air section includes a first axial air inlet hole opened in the center of the fairing, a second axial air inlet hole opened on the main impeller, a second radial air inlet hole opened on the main impeller, and a cooling cavity surrounded by the main bearing, the fan housing and the main mounting plate; The air inlet is in circular communication with the first axial air inlet hole, the second axial air inlet hole, the second radial air inlet hole, the cooling cavity and the air-cooling return air pipe.

6. The self-cooling air suspension fan according to claim 5, characterized in that: The second bearing cooling air section includes a first axial air inlet hole, a third axial air inlet hole provided on the first locking rod, a fourth axial air inlet hole provided on one end of the rotor, and second radial air outlet holes provided on the left and right side walls of the rotor; The air inlet is connected in sequence with the first axial air inlet hole, the second axial air inlet hole, the third axial air inlet hole, the fourth axial air inlet hole, the second radial air outlet hole, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole.

7. The self-cooling air suspension fan according to claim 6, characterized in that: The fifth axial air inlet hole, the sixth axial air inlet hole, the seventh axial air inlet hole, the second radial air outlet hole, the second cooling air section, the first axial air outlet hole and the first radial air outlet hole are connected in sequence.

8. A cooling method for a self-cooling air suspension fan according to claim 7, characterized in that: Including stator and rotor cooling method and bearing cooling method; The stator and rotor cooling method is as follows: the rotor drives the induced draft impeller to rotate, thereby generating negative pressure inside the fan housing. External cold air enters the fan housing through the first radial air inlet, then passes through the first cooling air section, the second cooling air section, the first axial air outlet, and finally is discharged from the fan housing through the first radial air outlet. When the cold air flows through the second cooling air section, the stator and rotor are cooled simultaneously. The bearing cooling method includes a main bearing cooling method, a left-end bearing cooling method and a right-end bearing cooling method. The main bearing cooling method is as follows: the rotor drives the main impeller to rotate, so that the static pressure of the air inlet is lower than the ambient static pressure. Since the air-cooling return air duct connects the cooling cavity and the air inlet, the pressure of the cooling cavity is lower than the ambient static pressure. The total pressure on the windward side of the main impeller is the sum of the dynamic pressure and the static pressure. Therefore, the total pressure on the windward side of the main impeller is higher than the pressure of the cooling cavity, that is, the total pressure of the first axial air inlet hole on the fairing is higher than the pressure of the cooling cavity, thereby generating a pressure difference. Under the action of the pressure difference, external cold air is discharged from the air inlet, the first axial air inlet hole, the second axial air inlet hole, the second radial air inlet hole, the cooling cavity and the air-cooling return air duct, and the cold air cools the main bearing after entering the cooling cavity; The cooling method for the left-end bearing and the right-end bearing is as follows: during the rotation of the rotor, the gas inside the rotor is discharged from the second radial air outlet under the action of centrifugal force, resulting in a negative pressure state inside the rotor, and external cold air enters through the air inlet and the fifth axial air inlet respectively, among which the cold air entering from the air inlet is discharged through the first axial air inlet, the second axial air inlet, the third axial air inlet, the fourth axial air inlet, the second radial air outlet, the second cooling air section, the first axial air outlet and the first radial air outlet in sequence, and cools the left-end bearing after entering the fan housing through the second radial air outlet; at the same time, the cold air entering from the fifth axial air inlet is discharged through the sixth axial air inlet, the seventh axial air inlet, the second radial air outlet, the second cooling air section, the first axial air outlet and the first radial air outlet in sequence, and cools the right-end bearing after entering the fan housing through the second radial air outlet.

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