A brushless motor with internal circulation cooling for an industrial axial flow fan

Abstract

The present invention relates to a brushless motor with internal circulation cooling for industrial axial fans. By arranging an external heat dissipation cavity, an internal heat dissipation cavity, a front circulation channel, a rear circulation channel and an impeller inside the motor, the cooling medium inside the motor circulates, and at the same time, by using the special structure of the cylinder body, the airflow driven when the industrial axial fan works flows through the outer wall of the cylinder body, quickly cools the outer wall of the cylinder body, and then quickly reduces the temperature of the cooling medium. When the cooling medium circulates into the internal heat dissipation cavity, it cools the inner side of the stator assembly. Since the motor cooling process does not require the intervention of external refrigerant, it can effectively avoid the problem that the external refrigerant brings pollutants into the motor interior, resulting in the pollution of the motor interior, and ensure that the motor can work safely and stably in an environment with a large concentration of pollutants and fully exert its kinetic energy.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to an inner-circulation cooling brushless motor for industrial axial fans. Background Art

[0002] The working environment of industrial axial fans is harsh, with a high concentration of pollutants in the environment (pollutants include, but are not limited to: oil fume, dust, water vapor), which is very unfriendly to the motors driving the fans. When the motors are cooled, pollutants in the external air are inhaled into the interior of the motors, resulting in internal pollution of the motors and affecting the service life of the motors. If a relatively thick filter layer is set, the cooling effect is reduced, leading to serious overheating of the motors. To overcome this problem, the commonly adopted technical solution is to reduce the power and speed of the motors, and reduce the motor heating by downshifting, but this method cannot fully exert the efficiency of the motors.

[0003] At present, there are some water-cooled motors that can water-cool the motors, thus greatly reducing the working temperature of the motors, enabling users to increase the motor speed and fully exert the kinetic energy of the motors. However, currently commonly used water-cooled motors all need to be connected to an external circulating water circuit. Such motors are more convenient to use in water-related fields, but when used in the field of industrial axial fans, the cost will be high due to the setting of the circulating water circuit, and it is not as cost-effective as using downshifting. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide an inner-circulation cooling brushless motor for industrial axial fans, and solve the technical problem that when traditional brushless motors are cooled, external refrigerants are required, resulting in the external refrigerants bringing pollutants into the interior of the motors and causing internal pollution of the motors.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows: a brushless motor with internal circulation cooling for an industrial axial flow fan, which includes a housing, a stator assembly fixedly arranged inside the housing, and a rotor assembly rotatably connected inside the housing and coaxially arranged with the stator assembly. One end of the rotating shaft of the rotor assembly extends outside the housing. The housing includes a front cover, a cylinder body, and a rear seat connected in sequence. A rear bearing assembly hole is provided on the front end face of the rear seat, and a central sleeve extending towards the front cover is coaxially arranged around the rear bearing assembly hole. The inner diameter of the central sleeve is larger than the outer diameter of the rotor core. The outer edge of the rear seat is connected to the rear end of the cylinder body, and the rotor assembly is arranged inside the central sleeve. A front bearing assembly hole and a shaft hole are provided on the front cover, and the front bearing assembly hole and the shaft hole are coaxially arranged. The shaft hole is located at the front part of the front cover. An outer sleeve extending towards the rear seat is provided on the front cover, and the outer sleeve is coaxially arranged with the shaft hole. The outer edge of the front cover is connected to the front end of the cylinder body. The central sleeve is inserted inside the outer sleeve, the front end of the central sleeve is hermetically connected to the front cover, and the rear end of the outer sleeve is hermetically connected to the rear seat. An annular installation cavity is formed between the central sleeve and the outer sleeve, and the stator assembly is installed in the annular installation cavity. The cylinder body is sleeved outside the outer sleeve and an outer heat dissipation cavity is formed between the cylinder body and the outer sleeve. An annular inner heat dissipation cavity is formed between the central sleeve and the rotor assembly. A plurality of rear circulation channels communicating the inner heat dissipation cavity and the outer heat dissipation cavity are arranged inside the rear seat, and a plurality of front circulation channels communicating the inner heat dissipation cavity and the outer heat dissipation cavity are arranged inside the front cover. An impeller is connected to the rotating shaft of the rotor assembly, and the impeller is located inside the inner heat dissipation cavity. The cylinder body includes a front ring, a rear ring, a cylinder body wound by corrugated plates, and end caps for connecting the ends of the cylinder body with the front ring and the rear ring. A large number of grooves extending along the axial direction are circumferentially and evenly distributed on the inner and outer walls of the cylinder body. The outer diameters of the front ring and the rear ring are equal to the outer diameters of the rear seat and the front cover, and the bottom of the grooves outside the cylinder body is flush with the outer circumferential surface of the front ring or the rear ring.

[0006] As a preferred solution, the outer edge of the front end of the rear seat radially contracts inwards to form a first annular step. The rear ring is fixedly welded to the outer edge of the first annular step, and an annular confluence groove is formed between the circumferential surface of the rear ring and the first annular step. One end of each of the rear circulation channels is circumferentially and evenly distributed on the circumferential surface of the first annular step and communicates with the annular confluence groove. The other end of each rear circulation channel extends to the periphery of the rear bearing assembly hole and is circumferentially and evenly distributed. The front end of the circumferential surface of the first annular step radially contracts inwards to form a second annular step. The outer sleeve is butted against the second annular step. A first sealing groove is radially contracted on the circumferential surface of the second annular step, and a first sealing ring is embedded in the first sealing groove. The first sealing ring abuts against the inner wall of the outer sleeve to achieve sealing.

[0007] As a preferred solution, a third annular step is provided on the outer edge of the front cover and faces the rear seat. The outer circumferential surface of the third annular step is the outer wall of the outer sleeve. An annular second sealing groove is coaxially provided on the platform surface of the third annular step. A second sealing ring is provided inside the second sealing groove. A convex ring matching the second sealing groove is provided on the front end surface of the front ring. The convex ring is inserted into the second sealing groove and is in sealing contact with the second sealing ring. One end of each of the front circulation channels is circumferentially distributed on the circumferential surface of the third annular step, and the other end of each front circulation channel extends to the periphery of the front bearing assembly hole and is circumferentially distributed.

[0008] As a preferred solution, the sum of the flow areas of all the rear circulation channels is greater than the sum of the flow areas of all the front circulation channels.

[0009] As a preferred solution, the rotating shaft and the shaft hole are sealed and connected through a sealing ring, and the rotating shaft can rotate relative to the sealing ring.

[0010] As a preferred solution, the impeller is arranged between the rotor core and the rear seat.

[0011] As a preferred solution, both the outer heat dissipation cavity and the inner heat dissipation cavity are filled with heat-conducting oil.

[0012] As a preferred solution, the rear bearing assembly hole is a blind hole.

[0013] As a preferred solution, a large number of heat dissipation fins extending along the axial direction of the outer sleeve are circumferentially distributed in the outer heat dissipation cavity. Each heat dissipation fin is welded to the barrel body of the cylinder, and each heat dissipation fin is arranged in each groove on the inner wall of the barrel body. Both ends of each heat dissipation fin are welded to the two end heads, and the end of the heat dissipation fin far from the inner wall of the barrel body abuts against the outer sleeve.

[0014] The beneficial effects of the present invention are as follows: By providing an outer heat dissipation cavity, an inner heat dissipation cavity, front circulation channels, rear circulation channels and an impeller inside the motor, the cooling medium inside the motor circulates, and at the same time, by using the special structure of the cylinder body, the airflow driven when the industrial axial flow fan works flows through the outer wall of the cylinder body, quickly cools the outer wall of the cylinder body, and then quickly reduces the temperature of the cooling medium. When the cooling medium circulates into the inner heat dissipation cavity, it cools the inner side of the stator assembly. Since the motor cooling process does not require the intervention of external refrigerant, the problem that external refrigerant brings pollutants into the motor and causes internal pollution of the motor can be effectively avoided, ensuring that the motor can work safely and stably in an environment with a large concentration of pollutants and fully exert its kinetic energy. Description of the Drawings

[0015] The following further details the specific embodiments of the present invention in conjunction with the drawings, where:

[0016] Figure 1It is a semi-sectional schematic diagram of a specific structure of the brushless motor with internal circulation cooling for industrial axial fans according to the present invention;

[0017] Figure 2 It is a semi-sectional structural schematic diagram of the rear seat according to the present invention;

[0018] Figure 3 It is a semi-sectional structural schematic diagram of the front cover according to the present invention;

[0019] Figure 4 It is a three-dimensional structural schematic diagram of the cylinder according to the present invention;

[0020] Figures 1 to 4 In the figure: 1. Outer shell; 101. Front cover; 102. Cylinder; 102a. Front ring; 102b. Rear ring; 102c. Cylinder body; 102d. Head; 103. Rear seat; 2. Stator assembly; 3. Rotor assembly; 301. Rotor core; 302. Rotating shaft; 4. Rear bearing assembly hole; 5. Central sleeve; 6. Front bearing assembly hole; 7. Shaft hole; 8. Outer sleeve; 9. Annular installation cavity; 10. Outer heat dissipation cavity; 11. Inner heat dissipation cavity; 12. Rear circulation channel; 13. Front circulation channel; 14. Impeller; 15. Groove; 16. First annular step; 17. Annular confluence groove; 18. Second annular step; 19. First sealing groove; 20. First sealing ring; 21. Third annular step; 22. Second sealing groove; 23. Second sealing ring; 24. Convex ring; 25. Sealing ring; 26. Heat dissipation fins; 27. Third sealing groove; 28. Third sealing ring. Specific embodiments

[0021] The following will describe in detail the specific implementation schemes of the present invention in conjunction with the accompanying drawings.

[0022] As Figures 1 to 4 shown, a brushless motor with internal circulation cooling for industrial axial fans includes an outer shell 1, a stator assembly 2 fixedly arranged in the outer shell 1, and a rotor assembly 3 rotatably connected in the outer shell 1 and coaxially arranged with the stator assembly 2. One end of the rotating shaft 302 of the rotor assembly 3 extends out of the outer shell 1. The outer shell 1 includes a front cover 101, a cylinder 102, and a rear seat 103 that are sequentially connected.

[0023] The front end face of the rear seat 103 is provided with a rear bearing assembly hole 4. A central sleeve 5 extending towards the front cover 101 is coaxially arranged around the rear bearing assembly hole 4. The inner diameter of the central sleeve 5 is larger than the outer diameter of the rotor core 301. The outer edge of the rear seat 103 is connected to the rear end of the cylinder 102. The rotor assembly 3 is arranged in the central sleeve 5, and the rear end of the rotating shaft 302 of the rotor assembly is rotatably connected to the rear bearing assembly hole 4 through a bearing.

[0024] The front cover 101 is provided with a front bearing assembly hole 6 and a shaft hole 7 that are connected to each other. The front bearing assembly hole 6 and the shaft hole 7 are coaxial. The shaft hole 7 is located at the front part of the front cover 101. The front cover 101 is provided with an outer sleeve 8 extending towards the rear seat 103. The outer sleeve 8 is coaxial with the shaft hole 7. The outer edge of the front cover 101 is connected to the front end of the cylinder 102. The front end of the rotating shaft 302 of the rotor assembly 3 is rotatably connected in the front bearing assembly hole 6 through a bearing and extends out of the front cover 101 through the shaft hole 7. The rotating shaft 302 is in sealed rotational connection with the shaft hole 7.

[0025] The central sleeve 5 is inserted inside the outer sleeve 8. The front end of the central sleeve 5 is sealingly connected to the front cover 101. The rear end of the outer sleeve 8 is sealingly connected to the rear seat 103. An annular installation cavity 9 is formed between the central sleeve 5 and the outer sleeve 8. The stator assembly 2 is installed in the annular installation cavity 9.

[0026] The cylinder 102 is sleeved outside the outer sleeve 8 and an outer heat dissipation cavity 10 is formed between the cylinder 102 and the outer sleeve 8. An annular inner heat dissipation cavity 11 is formed between the central sleeve 5 and the rotor assembly 3. A plurality of rear circulation channels 12 communicating the inner heat dissipation cavity 11 and the outer heat dissipation cavity 10 are provided inside the rear seat 103. A plurality of front circulation channels 13 communicating the inner heat dissipation cavity 11 and the outer heat dissipation cavity 10 are provided inside the front cover 101. An impeller 14 is connected to the rotating shaft 302 of the rotor assembly 3. The impeller 14 is located inside the inner heat dissipation cavity 11. When the impeller 14 rotates with the rotating shaft 302, the cooling medium inside the inner heat dissipation cavity 11 flows, forming a circulating flow of the cooling medium from the inner heat dissipation cavity 11 to the outer heat dissipation cavity 10 and then back to the inner heat dissipation cavity 11.

[0027] The cylinder 102 includes a front ring 102a, a rear ring 102b arranged coaxially, a cylinder body 102c wound by corrugated plates, and a head 102d for connecting the ends of the cylinder body 102c to the front ring 102a and the rear ring 102b. A large number of grooves 15 extending along its axial direction are circumferentially and uniformly distributed on the inner and outer walls of the cylinder body 102c. The outer diameters of the front ring 102a and the rear ring 102b are equal to the outer diameters of the rear seat 103 and the front cover 101. The bottom of the groove 15 outside the cylinder body 102c is flush with the outer circumferential surface of the front ring 102a or the rear ring 102b.

[0028] Since the cylinder body 102c extends beyond the outer diameters of the front ring 102a and the rear ring 102b, when the industrial axial flow fan is working, the air flow can flow along the grooves 15 on the cylinder body 102c, thereby quickly cooling the cylinder body 102c. Moreover, the cooling medium inside the cylinder body 102c can also be quickly cooled. After the cooling medium with reduced temperature returns to the inner heat dissipation cavity 11, it can cool the inner side of the stator assembly 2 and the rotor assembly 3, thereby fully reducing the working temperature of the motor. When cooling the motor, no external cooling medium is introduced, and thus the inside of the motor will not be contaminated.

[0029] In this embodiment, the cooling medium used is preferably dry and clean air, and in practical applications, conventional inert gases or heat-conducting oils can also be used.

[0030] In this embodiment, the outer edge of the front end of the rear seat 103 radially contracts inward to form a first annular step 16. The rear ring 102b is fixedly welded to the outer edge of the first annular step 16. An annular manifold groove 17 is formed between the circumferential surface of the rear ring 102b and the first annular step 16. One ends of the respective rear circulation channels 12 are circumferentially distributed on the circumferential surface of the first annular step 16 and communicate with the annular manifold groove 17. The other ends of the respective rear circulation channels 12 extend to the periphery of the rear bearing fitting hole 4 and are circumferentially distributed. The front end of the circumferential surface of the first annular step 16 radially contracts inward to form a second annular step 18. The outer sleeve 8 is butted against the second annular step 18. A first sealing groove 19 is radially contracted on the circumferential surface of the second annular step 18. A first sealing ring 20 is embedded in the first sealing groove 19. The first sealing ring 20 abuts against the inner wall of the outer sleeve 8 to achieve sealing.

[0031] The rear seat 103 of this structure is convenient for opening the rear circulation channels 12, and at the same time can achieve good sealed connection with the outer sleeve 8 and the cylinder body 102.

[0032] In this embodiment, a third annular step 21 facing the rear seat 103 is provided on the outer edge of the front cover 101. The outer circumferential surface of the third annular step 21 is the outer wall of the outer sleeve 8. An annular second sealing groove 22 is coaxially opened on the platform surface of the third annular step 21. A second sealing ring 23 is arranged inside the second sealing groove 22. A convex ring 24 cooperating with the second sealing groove 22 is provided on the front end surface of the front ring 102a. The convex ring 24 is inserted into the second sealing groove 22 and is in sealed abutment with the second sealing ring 23. One ends of the respective front circulation channels 13 are circumferentially distributed on the circumferential surface of the third annular step 21. The other ends of the respective front circulation channels 13 extend to the periphery of the front bearing fitting hole 6 and are circumferentially distributed.

[0033] The front cover 101 of this structure is convenient for opening the front circulation channels 13, and at the same time can achieve good sealed connection with the central sleeve 5 and the cylinder body 102.

[0034] As Figure 3 shown, the front end of the central sleeve 5 is inserted into a third sealing groove 27 opened on the front cover 101 and is sealed by a third sealing ring 28 embedded in the third sealing groove 27.

[0035] In this embodiment, it is preferably that the sum of the flow areas of all the rear circulation channels 12 is greater than the sum of the flow areas of all the front circulation channels 13. At the same time, when the motor rotates forward, the impeller 14 drives the cooling medium to flow in the circulation direction of the inner heat dissipation cavity 11, the rear circulation channels 12, the outer heat dissipation cavity 10, the front circulation channels, and the inner heat dissipation cavity 11, as Figure 1As shown. The advantage is that since the flow efficiency of the rear circulation channel 12 is greater than that of the front circulation channel 13, a slightly lower pressure is formed in the internal heat dissipation cavity 11, so as to reduce the shaft seal pressure between the rotating shaft 302 and the shaft hole 7 and avoid leakage of the cooling medium.

[0036] In this embodiment, the rotating shaft 302 and the shaft hole 7 are hermetically connected through a sealing ring 25, and the rotating shaft 302 can rotate relative to the sealing ring 25.

[0037] The impeller 14 is preferably arranged between the rotor core 301 and the rear seat 103. The driving ends of the impeller 14 and the rotating shaft 302 extending out of the housing 1 are respectively arranged at both ends of the rotor core 301, which can improve the rotational stability of the rotor assembly 3.

[0038] The rear bearing assembly hole 4 in this embodiment is a blind hole, which can eliminate the leakage of the cooling medium or the entry of external air into the motor.

[0039] In order to further improve the heat dissipation effect and the strength of the motor housing 1, in this embodiment, a large number of heat dissipation fins 26 extending axially along the outer sleeve 8 are circumferentially and uniformly distributed in the external heat dissipation cavity 10. Each heat dissipation fin 26 is welded to the barrel body 102c of the cylinder body 102, and each heat dissipation fin 26 is arranged in each groove 15 on the inner wall of the barrel body 102c. The two ends of each heat dissipation fin 26 are respectively welded to the two end heads 102d, and the end of the heat dissipation fin 26 far from the inner wall of the barrel body 102c abuts against the outer sleeve 8.

[0040] Since the heat dissipation fin 26 is welded to the barrel body 102c, its heat conduction efficiency is higher, and the cooling medium flowing through the heat dissipation fin 26 can obtain a faster cooling effect. At the same time, the heat dissipation fin 26 abuts against the outer sleeve 8, which can also conduct the heat on the outer sleeve 8 outward and improve the heat dissipation efficiency of the outer sleeve 8.

[0041] The working process of the present invention is as follows: As Figure 1 shown, the motor is assembled in a clean environment and then installed on an industrial axial flow fan. After the motor is started, the rotating shaft 302 drives the industrial axial flow fan to rotate. The industrial axial flow fan drives the air flow to flow from the rear of the motor to the front. The air flow cools the housing 1 of the motor, especially the barrel body 102c of the cylinder body 102, and at the same time cools the air in the external heat dissipation cavity 10. The rotating shaft 302 also drives the impeller 14 to rotate. The impeller 14 drives the hot air in the internal heat dissipation cavity 11 to flow into the rear circulation channel 12 and enter the external heat dissipation cavity 10 for heat dissipation. The air in the external heat dissipation cavity 10 returns to the internal heat dissipation cavity 11 through the front circulation channel 13 to dissipate heat from the inner side of the stator assembly 2 and the rotor assembly 3.

[0042] The above embodiments merely illustrate the principles and effects of the present invention and some applied embodiments, rather than limiting the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A brushless motor with internal circulation cooling for an industrial axial flow fan, comprising a housing (1), a stator assembly (2) fixedly arranged in the housing (1), and a rotor assembly (3) rotatably connected in the housing (1) and coaxially arranged with the stator assembly (2). One end of the rotating shaft (302) of the rotor assembly (3) extends out of the housing (1), and is characterized in that, The housing (1) includes a front cover (101), a cylinder body (102), and a rear seat (103) that are sequentially connected; A rear bearing assembly hole (4) is provided on the front end face of the rear seat (103). A central sleeve (5) extending towards the front cover (101) is coaxially arranged around the rear bearing assembly hole (4). The inner diameter of the central sleeve (5) is larger than the outer diameter of the rotor core (301). The outer edge of the rear seat (103) is connected to the rear end of the cylinder body (102). The rotor assembly (3) is arranged inside the central sleeve (5); A front bearing assembly hole (6) and a shaft hole (7) that are connected to each other are provided on the front cover (101). The front bearing assembly hole (6) and the shaft hole (7) are coaxial. The shaft hole (7) is located at the front part of the front cover (101). An outer sleeve (8) extending towards the rear seat (103) is provided on the front cover (101). The outer sleeve (8) is coaxial with the shaft hole (7). The outer edge of the front cover (101) is connected to the front end of the cylinder body (102); The central sleeve (5) is inserted inside the outer sleeve (8). The front end of the central sleeve (5) is hermetically connected to the front cover (101). The rear end of the outer sleeve (8) is hermetically connected to the rear seat (103). An annular installation cavity (9) is formed between the central sleeve (5) and the outer sleeve (8). The stator assembly (2) is installed inside the annular installation cavity (9); The cylinder body (102) is sleeved outside the outer sleeve (8) and an outer heat dissipation cavity (10) is formed between the cylinder body (102) and the outer sleeve (8). An annular inner heat dissipation cavity (11) is formed between the central sleeve (5) and the rotor assembly (3). A plurality of rear circulation channels (12) communicating the inner heat dissipation cavity (11) and the outer heat dissipation cavity (10) are arranged inside the rear seat (103). A plurality of front circulation channels (13) communicating the inner heat dissipation cavity (11) and the outer heat dissipation cavity (10) are arranged inside the front cover (101). An impeller (14) is connected to the rotating shaft (302) of the rotor assembly (3). The impeller (14) is located inside the inner heat dissipation cavity (11); The cylinder body (102) includes a front ring (102a), a rear ring (102b), a cylinder body (102c) wound by corrugated plates, and end caps (102d) for connecting the ends of the cylinder body (102c) to the front ring (102a) and the rear ring (102b). A large number of grooves (15) extending along the axial direction are circumferentially and uniformly distributed on the inner and outer walls of the cylinder body (102c). The outer diameters of the front ring (102a) and the rear ring (102b) are equal to the outer diameters of the rear seat (103) and the front cover (101). The bottoms of the grooves (15) outside the cylinder body (102c) are flush with the outer circumferential surfaces of the front ring (102a) or the rear ring (102b); The sum of the flow areas of all the rear circulation channels (12) is greater than the sum of the flow areas of all the front circulation channels (13); A large number of heat dissipation fins (26) extending along the axial direction of the outer sleeve (8) are circumferentially and uniformly distributed inside the outer heat dissipation cavity (10). Each heat dissipation fin (26) is welded to the barrel body (102c) of the barrel (102), and each heat dissipation fin (26) is disposed in each groove (15) on the inner wall of the barrel body (102c). The two ends of each heat dissipation fin (26) are respectively welded to the two end heads (102d), and the end of the heat dissipation fin (26) far from the inner wall of the barrel body (102c) abuts against the outer sleeve (8).

2. The brushless motor with internal circulation cooling for industrial axial fans according to claim 1, characterized in that, The outer edge of the front end of the rear seat (103) radially contracts inwards to form a first annular step (16). The rear ring (102b) is fixedly welded to the outer edge of the first annular step (16). An annular confluence groove (17) is formed between the circumferential surface of the rear ring (102b) and the first annular step (16). One end of each of the rear circulation channels (12) is circumferentially and uniformly distributed on the circumferential surface of the first annular step (16) and communicates with the annular confluence groove (17). The other end of each rear circulation channel (12) extends to the periphery of the rear bearing assembly hole (4) and is circumferentially and uniformly distributed. The front end of the circumferential surface of the first annular step (16) radially contracts inwards to form a second annular step (18). The outer sleeve (8) is butted against the second annular step (18). The circumferential surface of the second annular step (18) radially contracts to form a first sealing groove (19). A first sealing ring (20) is embedded in the first sealing groove (19), and the first sealing ring (20) abuts against the inner wall of the outer sleeve (8) to achieve sealing.

3. The brushless motor with internal circulation cooling for industrial axial fans according to claim 1, characterized in that, The outer edge of the front cover (101) is provided with a third annular step (21) facing the rear seat (103). The outer circumferential surface of the third annular step (21) is the outer wall of the outer sleeve (8). An annular second sealing groove (22) is coaxially opened on the platform surface of the third annular step (21). A second sealing ring (23) is disposed inside the second sealing groove (22). A convex ring (24) cooperating with the second sealing groove (22) is provided on the front end surface of the front ring (102a). The convex ring (24) is inserted into the second sealing groove (22) and is in sealing abutment with the second sealing ring (23). One end of each of the front circulation channels (13) is circumferentially and uniformly distributed on the circumferential surface of the third annular step (21), and the other end of each front circulation channel (13) extends to the periphery of the front bearing assembly hole (6) and is circumferentially and uniformly distributed.

4. The brushless motor with internal circulation cooling for industrial axial fans according to claim 1, characterized in that, The rotating shaft (302) is hermetically connected to the shaft hole (7) through a sealing ring (25), and the rotating shaft (302) can rotate relative to the sealing ring (25).

5. The brushless motor with internal circulation cooling for industrial axial fans according to claim 1, characterized in that, The impeller (14) is disposed between the rotor core (301) and the rear seat (103).

6. The brushless motor with internal circulation cooling for industrial axial fans according to claim 1, wherein, Both the outer heat dissipation cavity (10) and the inner heat dissipation cavity (11) are filled with heat-conducting oil.

7. The brushless motor with internal circulation cooling for industrial axial flow fans according to claim 1, characterized in that, The rear bearing assembly hole (4) is a blind hole.

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