Low start-stop speed long life air-float centrifugal air compressor

Abstract

The application discloses a low-start-stop-speed long-service-life air-float centrifugal air compressor, which is characterized by the following steps: setting an air path assembly in the compressor, improving the air pressure of the working environment of the radial bearing and the rotating shaft in the compressor, improving the air film bearing capacity of the radial bearing, reducing the start-stop speed of the radial bearing, prolonging the service life of the air compressor, and solving the problem that the air-float centrifugal air compressor has a short service life due to the contact friction between the gas bearing and the shaft sleeve during the start-stop process of the centrifugal air compressor.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of centrifugal air compressors, and particularly relates to a low-start-stop-speed long-service-life air-floating centrifugal air compressor. BACKGROUND

[0002] At present, the main types of hydrogen fuel cell air compressors on the market include scroll type, screw type and centrifugal type. Among them, the centrifugal air compressor has the advantages of good airtightness, compact structure, small vibration and noise, high energy conversion efficiency, and the like, and in addition, the hydrogen fuel cell stack has extremely high requirements for the cleanliness of air supply, so the oil-free lubrication and ultra-high speed air-floating bearing centrifugal air compressor becomes the current mainstream type of hydrogen fuel cell air compressor. However, the air-floating centrifugal air compressor has the problem of contact friction during start and stop, which is the main reason for limiting the service life. Therefore, how to reduce the start and stop speed of the air-floating centrifugal air compressor, reduce the start and stop friction, and improve the service life of the air compressor has become a problem to be solved at present. SUMMARY

[0003] The technical problem to be solved by the application is to provide a low-start-stop-speed long-service-life air-floating centrifugal air compressor to solve the problem that the gas bearing and the shaft sleeve are in contact and friction during the start and stop of the centrifugal air compressor, resulting in a short service life of the air-floating centrifugal air compressor.

[0004] To solve the above problems, the application adopts the following technical scheme:

[0005] A low-start-stop-speed long-service-life air-floating centrifugal air compressor, comprising a shell and an impeller tray arranged in the shell, a motor stator for driving a rotor to rotate is arranged on the right side of the impeller tray, an air path assembly for bearing the rotor is arranged on the right side of the impeller tray, the rotor comprises a rotating shaft and an impeller arranged at the end of the rotating shaft and located on the left side of the impeller tray, a second communication air channel and a first communication air channel for communicating the left side of the impeller tray and the air path assembly are arranged on the impeller tray, the first communication air channel and the second communication air channel are in communication, the air path assembly comprises, from right to left, a shaft sleeve arranged on the rotating shaft and two thrust bearings, the rotating shaft is sequentially provided with a thrust disc and two radial bearings on the right side of the impeller tray, the thrust disc is located between the two thrust bearings, a spacer ring with an inner diameter larger than the outer diameter of the thrust disc is arranged between the two thrust bearings, a thrust gas cavity is formed between the spacer ring and the thrust disc, a circumferential through hole is arranged on the spacer ring to communicate the second communication air channel and the thrust gas cavity, a radial bearing balance gas cavity is arranged on the shaft sleeve to communicate with the second communication air channel or the first communication air channel, and the circumferential through hole and the radial bearing balance gas cavity are communicated through the second communication air channel.

[0006] Further, the shaft sleeve comprises a first shaft sleeve sleeved on the rotating shaft and a second shaft sleeve sleeved outside the first shaft sleeve, the right part of the second shaft sleeve is in interference connection with the middle part of the first shaft sleeve, the left part of the second shaft sleeve and the left part of the first shaft sleeve are provided with a first gas balance cavity in communication with the first communication air channel, and the right side of the second shaft sleeve and the outside of the right part of the first shaft sleeve form a second gas balance cavity, and the second shaft sleeve is provided with a shaft sleeve communication air channel in communication with the first gas balance cavity and the second gas balance cavity.

[0007] The two radial bearings comprise a first radial bearing and a second radial bearing arranged in sequence from left to right, and the two sides of the first radial bearing and the second radial bearing are provided with annular air grooves, the first shaft sleeve is provided with a shaft sleeve communication hole for communicating the annular air grooves with the first gas balance cavity and the second gas balance cavity, the annular air groove on the right side of the first radial bearing is in communication with the first gas balance cavity through the shaft sleeve communication hole, and the annular air groove on the left side of the second radial bearing is in communication with the second gas balance cavity through the shaft sleeve communication hole; the annular air groove on the left side of the first radial bearing is in communication with the first gas balance cavity, and the annular air groove on the right side of the second radial bearing is in communication with the second gas balance cavity.

[0008] The end face of the second shaft sleeve is in connection with the thrust bearing and is provided with a shaft sleeve air inlet channel in communication with the second communication air channel; and the first gas balance cavity and the second gas balance cavity form a radial bearing balance cavity.

[0009] Further, the tail cavity is arranged on the right side of the motor stator in the shell, the radial bearing balance cavity is in communication with the tail cavity, the shell is provided with a shell communication air channel in communication with the tail cavity, and the shell communication air channel is in communication with the first communication air channel and / or the second communication air channel.

[0010] Further, the number of the circumferential through holes is at least two and is uniformly distributed along the circumference of the spacer ring, the outer circumferential surface of the spacer ring is provided with an annular groove, the annular groove and the circumferential through hole are in communication, and the second communication air channel is in communication with the annular groove.

[0011] Further, the impeller tray is provided with a containing cavity on the right side for containing the two thrust bearings and the end face of the shaft sleeve, the inner wall of the containing cavity in connection with the thrust bearing is provided with an annular step, the inner diameter of the annular step is smaller than the inner diameter of the thrust bearing, the first communication air channel is arranged on the annular step, the second communication air channel is arranged on the annular inner wall of the containing cavity and is in communication with the first communication air channel, and the shell is provided with a cover ring for fixing the shaft sleeve and the two thrust bearings on the impeller tray.

[0012] Further, the shell is provided with a cooling water jacket for wrapping the motor stator, the first shaft sleeve and the second shaft sleeve, and the second gas balance cavity is formed between the right side of the second shaft sleeve, the outside of the right part of the first shaft sleeve, the motor and the cooling water jacket.

[0013] Furthermore, a first sealing ring is provided between the outer circumference of the cooling water jacket and the shell on both sides. A first coolant inlet and a first coolant outlet are provided on the shell between the two first sealing rings. A spiral cooling groove is provided on the cooling water jacket. One end of the spiral cooling groove is connected to the first coolant inlet, and the other end of the spiral cooling groove is connected to the first coolant outlet.

[0014] Furthermore, an annular cooling cavity is provided between the cooling water jacket and the second shaft sleeve, and a second sealing ring is provided between the cooling water jacket and the second shaft sleeve to seal the annular cooling cavity. The cooling water jacket is provided with a second coolant inlet and a second coolant outlet that communicate with the annular cooling cavity. Both the second coolant inlet and the second coolant outlet are connected to the spiral cooling groove.

[0015] Furthermore, a one-way airway valve is provided in the first connecting airway.

[0016] The significant beneficial effects achieved by this invention are as follows:

[0017] A new type of air-float centrifugal air compressor with low start-stop speed and long service life is proposed. By setting up an air circuit component inside the compressor, the working environment air pressure of the radial bearing and shaft inside the compressor is increased, the air film bearing capacity of the radial bearing is improved, the start-stop speed of the radial bearing is reduced, and the service life of the air compressor is extended. This solves the problem of short service life of air-float centrifugal air compressors caused by contact friction between the gas bearing and the shaft sleeve during the start-stop process of current centrifugal air compressors. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the first internal cross-sectional structure of Embodiment 1 of the present invention;

[0019] Figure 2 This is a schematic diagram of the second internal cross-sectional structure of Embodiment 1 of the present invention;

[0020] Figure 3 This is a schematic diagram of the third internal cross-sectional structure of the present invention;

[0021] Figure 4 This is a schematic diagram of the cross-sectional structure of the bushing in this invention;

[0022] Figure 5 This is a schematic diagram of the cross-sectional structure of the cooling water jacket in this invention;

[0023] Figure 6 This is a schematic diagram of the rotating shaft structure in this invention;

[0024] Figure 7 This is a schematic diagram of the cross-sectional structure of the diaphragm ring in this invention;

[0025] Figure 8 This is a schematic diagram of the right side of the impeller tray in Embodiment 1 of the present invention;

[0026] Figure 9 This is a schematic diagram of the internal cross-sectional structure of Embodiment 2 of the present invention;

[0027] Figure 10 This is a schematic diagram of the left side structure of the impeller tray in Embodiment 2 of the present invention;

[0028] Figure 11 This is a schematic diagram of the right side structure of the impeller tray in Embodiment 2 of the present invention.

[0029] In the attached diagram, 1. Volute; 2. Outer casing; 3. Tail cover; 4. Impeller tray; 5. Motor stator; 6. Shaft; 7. Impeller; 8. Second connecting air passage; 10. First connecting air passage; 11. Thrust bearing; 12. Thrust plate; 13. Spacer ring; 14. Thrust chamber; 15. Circumferential through hole; 16. First bushing; 17. Second bushing; 18. First gas balance chamber; 19. Second gas balance chamber; 20. Bushing connecting air passage; 21. First radial bearing; 22. Second radial bearing; 23. Ring 24. Air groove; 25. Bushing connecting air hole; 26. Bushing air inlet; 27. Tail air chamber; 28. Housing connecting air passage; 29. ​​Annular groove; 30. Cavity; 31. Annular step; 32. Cover ring; 33. Cooling water jacket; 34. First sealing ring; 45. First coolant inlet; 46. First coolant outlet; 47. Spiral cooling groove; 48. Annular cooling chamber; 49. Second sealing ring; 40. Second coolant inlet; 40. Second coolant outlet; 51. One-way air passage valve; 52. Volute air chamber. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0031] Example 1

[0032] like Figures 1-8 As shown, a low start-stop speed and long life air-float centrifugal air compressor includes a housing and an impeller tray 4 installed inside the housing. A motor stator 5 for driving the rotor is installed on the right side of the impeller tray 4 and inside the housing. An air passage assembly for supporting the rotor is installed on the right side of the impeller tray 4. The rotor includes a shaft 6 and an impeller 7 installed at the end of the shaft 6 and located on the left side of the impeller tray 4. A gap is left between the impeller 7 and the impeller tray 4.

[0033] The housing includes a volute 1, an outer shell 2, and a tail cover 3 connected from left to right. The volute 1 is provided with a volute air chamber 52. The impeller tray 4 is installed between the volute 1 and the outer shell 2. The outer circumference of the impeller tray 4 is provided with two sealing rings that are respectively connected to the inner walls of the volute 1 and the outer shell 2. The center of the impeller tray 4 is provided with a through hole for the shaft 6 to pass through.

[0034] The impeller tray 4 is provided with a second connecting air passage 8 and a first connecting air passage 10 for connecting the left side of the impeller tray 4 and the air passage assembly. In this embodiment, the first connecting air passage 10 and the second connecting air passage 8 are connected. The air passage assembly is used to pressurize and bear the rotating shaft 6, thereby reducing the friction time and degree between the rotating shaft and the radial bearing and the bushing when the rotating shaft 6 starts and stops.

[0035] The air circuit assembly includes a bushing and two thrust bearings 11 mounted on the rotating shaft 6 from right to left. On the rotating shaft 6, a thrust plate 12 and two radial bearings are mounted on the right side of the impeller tray 4 from left to right. The two thrust bearings 11 are located on both sides of the thrust plate 12. A spacer 13 with an inner diameter larger than the outer diameter of the thrust plate 12 is provided between the two thrust bearings 11. A thrust air chamber 14 is formed between the spacer 13 and the thrust plate 12. A circumferential through hole 15 is provided on the spacer 13 to connect the second connecting air passage 8 with the thrust air chamber 14. A cover ring 34 is installed inside the housing to fix the bushing, the two thrust bearings 11 and the spacer 13 on the impeller tray 4. A radial bearing balance air chamber is provided on the bushing to connect with the second connecting air passage 8. The radial bearing balance air chamber is used to form a high-pressure air chamber to support the rotating shaft 6.

[0036] In this embodiment, the first connecting air passage 10 is connected to the circumferential through hole 15 and the radial bearing balance air chamber through the second connecting air passage 8, and the circumferential through hole 15 and the radial bearing balance air chamber are connected through the second connecting air passage 8. That is to say, the thrust air chamber 14 and the radial bearing balance air chamber are connected to form a consistent high-pressure air chamber to support the rotor.

[0037] The impeller tray 4 has a cavity 30 on the right side. The two thrust bearings 11 and the end face of the bushing are fixed by the cover ring 34 and located in the cavity 30. The inner wall of the left side of the cavity 30 has an annular step 33 with an inner diameter smaller than that of the thrust bearings 11. The first connecting air passage 10 is opened on the annular step 33 in the circumferential direction along the annular step 33. There is at least one first connecting air passage 10. In this embodiment, there are four first connecting air passages 10 that are evenly distributed.

[0038] The second connecting air passage 8 is opened on the annular inner wall of the cavity 30. There is at least one second connecting air passage 8. The circumferential through hole 15 corresponds to the position of the second connecting air passage 8. High pressure gas enters the thrust chamber 14 through the gap between the impeller 7 and the impeller tray 4, the gap between the impeller tray 4 and the shaft 6, the first connecting air passage 10, the second connecting air passage 8 and the circumferential through hole 15 as the air source for the air-bearing thrust bearing 11 to support the thrust plate 12 and reduce the friction between the thrust plate 12 and the thrust bearing 11. Furthermore, in order to improve the air intake efficiency, an annular groove 29 communicating with the circumferential through hole 15 is provided on the outer circumferential surface of the partition ring 13. The opening of the annular groove 29 forms an annular cavity. Gas enters multiple circumferential through holes 15 through the annular cavity via the second connecting air passage 8, thereby improving the air intake efficiency. At this time, there can be multiple second connecting air passages 8.

[0039] The bushing includes a first bushing 16 sleeved on the rotating shaft 6 and a second bushing 17 sleeved outside the first bushing 16. The inner wall of the second bushing 17 is stepped from left to right. The right part of the second bushing 17 is interference-fitted with the middle part of the first bushing 16. A first gas balance chamber 18 communicating with the second connecting air passage 8 is provided between the left part of the second bushing 17 and the left part of the first bushing 16. A second gas balance chamber 19 is formed between the right side of the second bushing 17 and the outer side of the right part of the first bushing 16. A bushing connecting air passage 20 communicating with the first gas balance chamber 18 and the second gas balance chamber 19 is provided on the second bushing 17.

[0040] The end face of the second bushing 17 is provided with abutting protrusions that protrude toward the thrust bearing 11. There are four abutting protrusions, and a bushing air inlet 25 is formed between each pair of abutting protrusions. The second connecting airway 8 is connected to the first gas balance air chamber 18 through the bushing air inlet 25. There is a gap between the end face of the first bushing 16 and the thrust bearing 11.

[0041] The two radial bearings include a first radial bearing 21 and a second radial bearing 22 arranged from left to right. Both sides of the first radial bearing 21 and the second radial bearing 22 are provided with annular air grooves 23. The annular air groove 23 on the left side of the first radial bearing 21 is connected to the first gas balance air chamber 18 through the gap between the first bushing 16 and the thrust bearing 11.

[0042] The first bushing 16 is provided with a bushing connecting vent 24 for connecting the annular gas groove 23 with the first gas balance chamber 18 and the second gas balance chamber 19. The annular gas groove 23 on the right side of the first radial bearing 21 is connected to the first gas balance chamber 18 through the bushing connecting vent 24, and the annular gas groove 23 on the left side of the second radial bearing 22 is connected to the second gas balance chamber 19 through the bushing connecting vent 24. The bushing vents are multiple and evenly distributed around the annular gas groove 23.

[0043] The right end of the first bushing 16 extends above the annular air groove 23 on the right side of the second radial bearing 22, but does not completely block it. The annular air groove 23 on the right side of the second radial bearing 22 is thus connected to the second gas balance chamber 19.

[0044] The first gas balancing chamber 18 and the second gas balancing chamber 19 form a radial bearing balancing chamber.

[0045] To further enhance the effect, a tail gas chamber 26 is provided inside the housing on the right side of the motor stator 5. The second gas balance chamber 19 in the radial gas balance chamber is connected to the tail gas chamber 26. A housing connecting air passage 27 is provided on the outer shell 2, which is connected to the tail gas chamber 26. The housing connecting air passage 27 is connected to the first connecting air passage 10 and / or the second connecting air passage 8. In this embodiment, the housing connecting air passage 27 is connected to the second connecting air passage 8.

[0046] The housing connecting air passage 27 is parallel to the axial direction of the bushing; the housing connecting air passage 27 is located on the outer shell 2 inside the housing;

[0047] The housing connecting air passage 27 forms a closed-loop gas passage through communication with the second connecting air passage 8;

[0048] The second gas balance chamber 19 is connected to the tail chamber 26 through the gap between the motor stator 5 and the rotor. It should be noted that in this embodiment, the second connecting air passage 8 is a vertically flipped L-shape, that is, the second connecting air passage 8 extends to the right side of the impeller tray 4 to connect with the housing connecting air passage 27.

[0049] In order to avoid the working temperature inside the housing 2 being too high during operation, the housing 2 is equipped with an inner cooling water jacket 35 that wraps the motor stator 5, the first bushing 16 and the second bushing 17. The second gas balance chamber 19 mentioned above is formed between the right outer side of the second bushing 17, the motor and the cooling water jacket 35.

[0050] The cooling water jacket 35 has first sealing rings 37 installed on both sides of its outer circumference and between it and the housing for sealing. The housing has a first coolant inlet 43 and a first coolant outlet 44 located between the two first sealing rings 37. The cooling water jacket 35 has a spiral cooling groove 45 around it. One end of the spiral cooling groove 45 is connected to the first coolant inlet 43, and the other end of the spiral cooling groove 45 is connected to the first coolant outlet 44. The cooling water jacket 35 is used to absorb and dissipate the heat generated by the motor stator 5 and rotor during operation.

[0051] In order to further absorb the heat generated during the rotation of the rotating shaft 6, an annular cooling cavity 46 is provided between the cooling water jacket 35 and the second shaft sleeve 17, surrounding the second shaft sleeve 17. A second sealing ring 47 for sealing the annular cooling cavity 46 is installed between the cooling water jacket 35 and the second shaft sleeve 17. The cooling water jacket 35 is provided with a second coolant inlet 48 and a second coolant outlet 49 that communicate with the annular cooling cavity 46. Both the second coolant inlet 48 and the second coolant outlet 49 are connected to the spiral cooling groove 45.

[0052] When the compressor is working, the impeller 7 drives the air to form a high-speed airflow. After entering the volute 1, the airflow is decelerated and pressurized to form high-pressure gas. The high-pressure gas passes sequentially through the gap between the impeller 7 and the impeller tray 4, the gap between the impeller tray 4 and the shaft 6, the gap between the thrust bearing 11 and the left wall of the cavity 30, the first connecting air passage 10, and the second connecting air passage 8 to connect with the air passage assembly on the right side of the impeller tray 4. After passing through the second connecting air passage 8, the high-pressure gas enters the annular groove 29 and the radial bearing air chamber respectively. The high-pressure gas enters the thrust air chamber 14 through the annular groove 29 and the circumferential through hole 15 to form a high-pressure air chamber surrounding the thrust plate 12. The high-pressure gas passes through the bushing inlet 25 and the first gas balance gas in the radial bearing air chamber. The cavity 18 is connected to the second gas balance cavity 19, and then through the bushing vent and the annular air groove 23, a high-pressure air chamber is formed at the location of the rotating shaft 6, which is consistent with the thrust air chamber 14. At the same time, the setting of the tail air chamber 26 will also form a high-pressure air chamber at the location of the motor stator 5, which is consistent with the thrust air chamber 14. Thus, the right side of the impeller tray 4 forms a bearing force consistent with the rotor. When the motor starts or stops, the presence of the high-pressure air chamber can reduce the friction time and degree between the rotating shaft 6 and the radial bearing and the bushing during start-up and shutdown. This solves the problem of short service life of air-float centrifugal air compressors caused by the contact friction between the gas bearing and the bushing during the start-up and shutdown process of the current centrifugal air compressor.

[0053] Example 2

[0054] like Figures 3-7 and Figures 9-11 As shown, the structure of this embodiment is roughly the same as that of embodiment 1. The difference between this embodiment and embodiment 1 is that in this embodiment, the first connecting air passage 10 is a through hole opened on the impeller tray 4. The left end of the first connecting air passage 10 is connected to the volute air chamber 52 in the volute 1, and the right end of the first connecting air passage 10 is connected to the shell connecting air passage 27. A one-way air passage valve 51 is installed on the first connecting air passage 10. The installation of the one-way air passage valve 51 is used to prevent the pressure in the air passage assembly from depressurizing too quickly when the pressure on the left side of the impeller tray 4 is less than the pressure in the air passage assembly.

[0055] In this embodiment, the first connecting air passage 10 is connected to the housing connecting air passage 27, the tail air chamber 26, the radial bearing air chamber, the second connecting air passage 8, and the thrust air chamber 14.

[0056] In this embodiment, the second connecting airway 8 is only opened on the annular inner wall of the cavity 30. The number of the second connecting airway 8 can be one or more. In this embodiment, the number of the second connecting airway 8 is four.

[0057] In this embodiment, after the high-pressure gas enters through the first connecting air passage 10, it enters the thrust air chamber 14 through the housing connecting air passage 27, the tail air chamber 26, the second gas balance air chamber 19, the first gas balance air chamber 18, and the second connecting gas passage to form a high-pressure air chamber that bears the rotor, thus creating a consistent bearing force on the rotor. When the motor starts or stops, the presence of the high-pressure air chamber can reduce the friction time and degree between the shaft 6 and the radial bearing and the bushing during start-up and shutdown, thus solving the problem of short service life of air-float centrifugal air compressors caused by the contact friction between the gas bearing and the bushing during the start-up and shutdown process of current centrifugal air compressors.

[0058] It should be noted that the first radial bearing 21 and the second radial bearing 22 referred to in this application are both gas bearings as described in the prior art.

Claims

1. A low start-stop speed and long lifespan air-float centrifugal air compressor, characterized in that: The device includes a housing and an impeller tray (4) disposed within the housing. A motor stator (5) for driving the rotor is disposed on the right side of the impeller tray (4). An air passage assembly for supporting the rotor is disposed on the right side of the impeller tray (4). The rotor includes a shaft (6) and an impeller (7) disposed at the end of the shaft (6) and located on the left side of the impeller tray (4). A second connecting air passage (8) and a first connecting air passage (10) for connecting the left side of the impeller tray (4) and the air passage assembly are provided on the impeller tray (4). The first connecting air passage (10) and the second connecting air passage (8) are connected. The air passage assembly includes a bushing and two thrust bearings (11) sequentially fitted onto the shaft (6) from right to left. The upper part of the shaft (6)... A thrust plate (12) and two radial bearings are arranged sequentially on the right side of the impeller tray (4). The thrust plate (12) is located between the two thrust bearings (11). A spacer (13) with an inner diameter larger than the outer diameter of the thrust plate (12) is arranged between the two thrust bearings (11). A thrust air chamber (14) is formed between the spacer (13) and the thrust plate (12). A circumferential through hole (15) is provided on the spacer (13) to connect the second connecting air passage (8) with the thrust air chamber (14). A radial bearing balance air chamber is provided on the bushing to connect with the second connecting air passage (8) or the first connecting air passage (10). The circumferential through hole (15) and the radial bearing balance air chamber are connected through the second connecting air passage (8). The bushing includes a first bushing (16) sleeved on the rotating shaft (6) and a second bushing (17) sleeved outside the first bushing (16). The right side of the second bushing (17) is press-fitted to the middle of the first bushing (16). A first gas balance chamber (18) communicating with a first communicating air passage (10) is provided between the left side of the second bushing (17) and the left side of the first bushing (16). A second gas balance chamber (19) is formed between the right side of the second bushing (17) and the outer side of the right side of the first bushing (16). A bushing communicating air passage (20) communicating with the first gas balance chamber (18) and the second gas balance chamber (19) is provided on the second bushing (17). The two radial bearings include a first radial bearing (21) and a second radial bearing (22) arranged sequentially from left to right. Both sides of the first radial bearing (21) and the second radial bearing (22) are provided with annular air grooves (23). The first bushing (16) is provided with a bushing communication air hole (24) for connecting the annular air grooves (23) with the first gas balance chamber (18) and the second gas balance chamber (19). The annular air groove (23) on the right side of the first radial bearing (21) is connected to the first gas balance chamber (18) through the bushing communication air hole (24). The annular air groove (23) on the left side of the second radial bearing (22) is connected to the second gas balance chamber (19) through the bushing communication air hole (24). The annular air groove (23) on the left side of the first radial bearing (21) is connected to the first gas balance chamber (18), and the annular air groove (23) on the right side of the second radial bearing (22) is connected to the second gas balance chamber (19). The end face of the second bushing (17) is connected to the thrust bearing (11) and is provided with a bushing inlet (25) that communicates with the second communicating air passage (8); the first gas balance chamber (18) and the second gas balance chamber (19) form the radial bearing balance chamber.

2. The air-float centrifugal air compressor with low start-stop speed and long service life according to claim 1, characterized in that: The housing is provided with a tail air chamber (26) located on the right side of the motor stator (5). The radial bearing balance air chamber is connected to the tail air chamber (26). The housing is provided with a housing connecting air passage (27) connected to the tail air chamber (26). The housing connecting air passage (27) is connected to the first connecting air passage (10) and / or the second connecting air passage (8).

3. The air-float centrifugal air compressor with low start-stop speed and long service life according to claim 1, characterized in that: The number of circumferential through holes (15) is at least two and they are evenly distributed along the circumference of the partition ring (13). The outer circumferential surface of the partition ring (13) is provided with an annular groove (29). The annular groove (29) and the circumferential through holes (15) are connected. The second connecting air passage (8) is connected to the annular groove (29).

4. The air-float centrifugal air compressor with low start-stop speed and long service life according to claim 1, characterized in that: The impeller tray (4) has a cavity (30) on the right side for accommodating the two thrust bearings (11) and the end face of the bushing. The inner wall of the cavity (30) connected to the thrust bearing (11) is provided with an annular step (33). The inner diameter of the annular step (33) is smaller than the inner diameter of the thrust bearing (11). The first connecting air passage (10) is opened on the annular step (33). The second connecting air passage (8) is opened on the annular inner wall of the cavity (30) and communicates with the first connecting air passage (10). The housing is provided with a cover ring (34) for fixing the bushing and the two thrust bearings (11) on the impeller tray (4).

5. A low start-stop speed, long lifespan air-float centrifugal air compressor according to claim 1, characterized in that: The housing is provided with a cooling water jacket (35) that encloses the motor stator (5), the first bushing (16) and the second bushing (17). A second gas balance chamber (19) is formed between the right side of the second bushing (17), the outer side of the right side of the first bushing (16), the motor stator (5) and the cooling water jacket (35).

6. A low start-stop speed, long lifespan air-float centrifugal air compressor according to claim 5, characterized in that: The outer circumferential surface of the cooling water jacket (35) is provided with a first sealing ring (37) between the two sides of the housing. The housing is provided with a first coolant inlet (43) and a first coolant outlet (44) between the two first sealing rings (37). The cooling water jacket (35) is provided with a spiral cooling groove (45). One end of the spiral cooling groove (45) is connected to the first coolant inlet (43), and the other end of the spiral cooling groove (45) is connected to the first coolant outlet (44).

7. A low start-stop speed, long lifespan air-float centrifugal air compressor according to claim 6, characterized in that: An annular cooling chamber (46) is provided between the cooling water jacket (35) and the second bushing (17). A second sealing ring (47) for sealing the annular cooling chamber (46) is provided between the cooling water jacket (35) and the second bushing (17). The cooling water jacket (35) is provided with a second coolant inlet (48) and a second coolant outlet (49) communicating with the annular cooling chamber (46). Both the second coolant inlet (48) and the second coolant outlet (49) are connected to the spiral cooling groove (45).

8. A low start-stop speed and long lifespan air-float centrifugal air compressor according to claim 1, characterized in that: The first connecting airway (10) is equipped with a one-way airway valve (51).

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