Air floatation centrifugal air compressor with low start-stop rotating speed and long service life

Abstract

According to the air flotation centrifugal air compressor with the low start-stop rotating speed and the long service life, the air path assembly is arranged in the compressor, the working environment air pressure of the radial bearing and the rotating shaft in the compressor is improved, the air film bearing capacity of the radial bearing is improved, the start-stop rotating speed of the radial bearing is reduced, and the service life of the air compressor is prolonged; the problem that in the starting and stopping process of an existing centrifugal air compressor, a gas bearing and a shaft sleeve are in contact friction, and consequently the service life of the air floating centrifugal air compressor is short is solved.

Description

Technical Field

[0001] The invention belongs to the field of centrifugal air compressors, and in particular relates to an air-floating centrifugal air compressor with low start-stop speed and long service life. Background Art

[0002] In order to achieve the dual carbon goals of "carbon peak" and "carbon neutrality", the development of hydrogen energy has become the only way for my country's energy transformation. As a key technology for converting hydrogen energy into electrical energy, the application of hydrogen fuel cell system in the transportation field is particularly important. As one of the key core components in the hydrogen fuel cell system, the air compressor is responsible for delivering clean air of specific pressure and flow to the stack in the hydrogen fuel cell system, providing the necessary oxygen for the stack reaction and power generation, and is figuratively called the "lungs" of the hydrogen fuel cell system. At present, the main types of hydrogen fuel cell air compressors on the market include vortex, screw and centrifugal. Among them, the centrifugal air compressor has the advantages of good airtightness, compact structure, low vibration and noise, high energy conversion efficiency, and the hydrogen fuel cell stack has extremely high requirements for the cleanliness of the air supply, so the oil-free lubrication and ultra-high speed air bearing centrifugal air compressor has become the current mainstream type of hydrogen fuel cell air compressor. However, there is a contact friction problem in the start-stop process of the air-floating centrifugal air compressor, which is the main reason for limiting its service life. Therefore, how to reduce the start-stop speed of the air-floating centrifugal air compressor, reduce the start-stop friction, and increase the service life of the air compressor has become a problem that needs to be solved urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a low start-stop speed and long life air-floating centrifugal air compressor to solve the problem of short service life of the air-floating centrifugal air compressor caused by contact and friction between the gas bearing and the sleeve during the start-stop process of the current centrifugal air compressor.

[0004] In order to solve the above problems, the present invention adopts the following technical solutions:

[0005] A low start-stop speed and long life air-floating centrifugal air compressor, comprising a housing and an impeller tray arranged in the housing, a motor stator for driving a rotor to rotate is arranged on the right side of the impeller tray, an air path assembly for carrying 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 communicating air channel and a first communicating air channel for connecting the left side of the impeller tray and the air path assembly are arranged on the impeller tray, the first communicating air channel and the second communicating air channel are connected, and the air path assembly comprises a sleeve arranged in sequence from right to left A shaft sleeve and two thrust bearings are arranged on the rotating shaft, and a thrust plate and two radial bearings are arranged in sequence on the right side of the impeller plate on the rotating shaft. The thrust plate is located between the two thrust bearings. A spacer ring with an inner diameter larger than the outer diameter of the thrust plate is arranged between the two thrust bearings. A thrust air cavity is formed between the spacer ring and the thrust plate. A circumferential through hole is provided on the spacer ring for connecting the second connecting air channel with the thrust air cavity. A radial bearing balancing air cavity connected to the second connecting air channel or the first connecting air channel is provided on the shaft sleeve, and the circumferential through hole and the radial bearing balancing air cavity are connected via the second connecting air channel.

[0006] Further, the shaft sleeve includes 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 interference connected with the middle part of the first shaft sleeve, a first gas balancing air cavity communicating with the first communicating air passage is provided between the left part of the second shaft sleeve and the left part of the first shaft sleeve, a second gas balancing air cavity is formed between the right side of the second shaft sleeve and the outer side of the right part of the first shaft sleeve, and a shaft sleeve communicating air passage communicating with the first gas balancing air cavity and the second gas balancing air cavity is provided on the second shaft sleeve;

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

[0008] The second sleeve end surface is connected to the thrust bearing and is provided with a sleeve air inlet channel connected to the second connecting air channel; the first gas balancing air cavity and the second gas balancing air cavity form a radial bearing balancing air cavity.

[0009] Furthermore, a tail air cavity is arranged in the shell on the right side of the motor stator, the radial bearing balance cavity is connected with the tail air cavity, a shell connecting air passage connected with the tail air cavity is arranged on the shell, and the shell connecting air passage is connected with the first connecting air passage and / or the second connecting air passage.

[0010] Furthermore, the number of the circumferential through holes is at least two and they are evenly distributed along the circumference of the spacer ring. An annular groove is provided on the outer circumference of the spacer ring. The annular groove is connected to the circumferential through holes, and the second communicating airway is connected to the annular groove.

[0011] Furthermore, a cavity for accommodating two thrust bearings and an end face of a sleeve is provided on the right side of the impeller tray, an annular step is provided on the inner wall where the cavity is connected to the thrust bearing, the inner diameter of the annular step is smaller than the inner diameter of the thrust bearing, a first connecting air channel is provided on the annular step, a second connecting air channel is provided on the annular inner wall of the cavity and is connected to the first connecting air channel, and a cover ring for fixing the sleeve and two thrust bearings on the impeller tray is provided in the shell.

[0012] Furthermore, a cooling water jacket is provided in the shell to wrap the motor stator, the first sleeve and the second sleeve, and a second gas balance air cavity is formed on the right side of the second sleeve, the outer side of the right part of the first sleeve, and between the motor and the cooling water jacket.

[0013] Furthermore, first sealing rings are provided between the shell and both sides of the outer circumference of the cooling water jacket, a first coolant inlet and a first coolant outlet are provided on the shell between the two first sealing rings, and 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 arranged between the cooling water jacket and the second shaft sleeve, a second sealing ring for closing the annular cooling cavity is arranged between the cooling water jacket and the second shaft sleeve, a second coolant inlet and a second coolant outlet connected to the annular cooling cavity are arranged on the cooling water jacket, and the second coolant inlet and the second coolant outlet are both 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 the present invention are:

[0017] The invention discloses an air-floating centrifugal air compressor with low start-stop speed and long service life. The air path component is arranged in the compressor to increase the working environment air pressure of the radial bearing and the rotating shaft in the compressor, increase the air film bearing capacity of the radial bearing, reduce the start-stop speed of the radial bearing, and extend the service life of the air compressor. The invention solves the problem of short service life of the air-floating centrifugal air compressor caused by contact and friction between the gas bearing and the shaft sleeve during the start-stop process of the centrifugal air compressor. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0021] Figure 4 It is a schematic diagram of the cross-sectional structure of the shaft sleeve in the present invention;

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

[0023] Figure 6 It is a schematic diagram of the rotating shaft structure of the present invention;

[0024] Figure 7 It is a schematic diagram of the cross-sectional structure of the septum ring of the present invention;

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

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

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

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

[0029] In the attached drawings, 1, volute; 2, outer shell; 3, tail cover; 4, impeller tray; 5, motor stator; 6, rotating shaft; 7, impeller; 8, second communicating air passage; 10, first communicating air passage; 11, thrust bearing; 12, thrust plate; 13, spacer ring; 14, thrust air cavity; 15, circumferential through hole; 16, first sleeve; 17, second sleeve; 18, first gas balance air cavity; 19, second gas balance air cavity; 20, sleeve communicating air passage; 21, first radial bearing; 22, second radial bearing; 23, ring shaped air groove; 24, sleeve connecting air hole; 25, sleeve air inlet; 26, tail air cavity; 27, shell connecting air duct; 29, annular groove; 30, cavity; 33, annular step; 34, cover ring; 35, cooling water jacket; 37, first sealing ring; 43, first coolant inlet; 44, first coolant outlet; 45, spiral cooling groove; 46, annular cooling cavity; 47, second sealing ring; 48, second coolant inlet; 49, second coolant outlet; 51, one-way airway valve; 52, volute air cavity. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] Example 1

[0032] like Figure 1-Figure 8 As shown, a low start-stop speed and long life air-floating centrifugal air compressor comprises a housing and an impeller tray 4 installed in the housing, a motor stator 5 for driving the rotor to rotate is installed on the right side of the impeller tray 4 and located in the housing, an air path assembly for carrying the rotor is installed on the right side of the impeller tray 4, the rotor comprises a rotating shaft 6 and an impeller 7 installed at the end of the rotating shaft 6 and located on the left side of the impeller tray 4, and a gap is left between the impeller 7 and the impeller tray 4;

[0033] Among them, the shell includes a volute 1, an outer shell 2 and a tail cover 3 which are connected in sequence from left to right. The volute 1 is provided with a volute air cavity 52, and an impeller tray 4 is installed between the volute 1 and the outer shell 2. The outer peripheral surface of the impeller tray 4 is provided with two sealing rings which are respectively connected to the inner walls of the volute 1 and the outer shell 2. A through hole for the rotating shaft 6 to pass through is opened at the center position of the impeller tray 4.

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

[0035] The air path assembly includes a sleeve and two thrust bearings 11 which are sequentially sleeved on the rotating shaft 6 from right to left. A thrust plate 12 and two radial bearings are sequentially arranged from left to right on the rotating shaft 6 on the right side of the impeller tray 4. The two thrust bearings 11 are respectively arranged on both sides of the thrust plate 12. A spacer ring 13 whose inner diameter is larger than the outer diameter of the thrust plate 12 is arranged between the two thrust bearings 11. A thrust air cavity 14 is formed between the spacer ring 13 and the thrust plate 12. A circumferential through hole 15 is opened on the spacer ring 13 to connect the second connecting air passage 8 with the thrust air cavity 14. A cover ring 34 for fixing the sleeve, the two thrust bearings 11 and the spacer ring 13 on the impeller tray 4 is installed in the housing. A radial bearing balancing air cavity which is connected with the second connecting air passage 8 is arranged on the sleeve. The radial bearing balancing air cavity is used to form a high-pressure air chamber to carry the rotating shaft 6.

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

[0037] A cavity 30 is provided on the right side of the impeller tray 4, two thrust bearings 11 and the end face of the sleeve are fixed by a cover ring 34 and are located in the cavity 30, an annular step 33 with an inner diameter smaller than the thrust bearing 11 is provided on the left inner wall of the cavity 30, and the first communicating air passage 10 is opened on the annular step 33 along the circumferential direction of the annular step 33, and the number of the first communicating air passage 10 is at least one, and in this embodiment, the number of the first communicating air passage 10 is four and is evenly distributed;

[0038] The second communicating air channel 8 is provided on the annular inner wall in the cavity 30, and the number of the second communicating air channel 8 is at least one. The circumferential through hole 15 corresponds to the position of the second communicating air channel 8. The high-pressure gas enters the thrust air cavity 14 through the gap between the impeller 7 and the impeller tray 4, the gap between the impeller tray 4 and the rotating shaft 6, the first communicating air channel 10, the second communicating air channel 8 and the circumferential through hole 15, and serves as the air source of the air-floating thrust bearing 11 to support the thrust plate 12, thereby reducing the friction between the thrust plate 12 and the thrust bearing 11; further, in order to improve the air intake efficiency, an annular groove 29 connected to the circumferential through hole 15 is provided on the outer peripheral surface of the spacer ring 13, and an annular cavity is formed by the opening of the annular groove 29, and the gas enters the multiple circumferential through holes 15 through the annular cavity through the second communicating air channel 8, thereby improving the air intake efficiency. At this time, the number of the second communicating air channels 8 can be multiple;

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

[0040] The end surface of the second sleeve 17 is provided with abutment protrusions protruding toward the thrust bearing 11, and the number of the abutment protrusions is four, and a sleeve air inlet 25 is formed between two abutment protrusions, and the second communication air channel 8 is connected with the first gas balance air chamber 18 through the sleeve air inlet 25; there is a gap between the end surface of the first sleeve 16 and the thrust bearing 11;

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

[0042] The first sleeve 16 is provided with a sleeve communicating air hole 24 for connecting the annular air groove 23 with the first gas balancing air cavity 18 and the second gas balancing air cavity 19. The annular air groove 23 on the right side of the first radial bearing 21 is connected with the first gas balancing air cavity 18 through the sleeve communicating air hole 24, and the annular air groove 23 on the left side of the second radial bearing 22 is connected with the second gas balancing air cavity 19 through the sleeve communicating air hole 24. There are multiple sleeve vents and they are evenly distributed around the annular air groove 23.

[0043] The right end of the first sleeve 16 extends to the upper side of the annular gas groove 23 on the right side of the second radial bearing 22, but does not completely block the annular gas groove 23 on the right side of the second radial bearing 22, so that the annular gas groove 23 on the right side of the second radial bearing 22 is connected with the second gas balance air chamber 19;

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

[0045] In order to further expand the effect, a tail air cavity 26 is provided in the housing on the right side of the motor stator 5, the second gas balance air cavity 19 in the radial gas balance cavity is connected to the tail air cavity 26, and a housing communicating air passage 27 connected to the tail air cavity 26 is provided on the housing 2, the housing communicating air passage 27 is connected to the first communicating air passage 10 and / or the second communicating air passage 8, and in this embodiment, the housing communicating air passage 27 is connected to the second communicating air passage 8;

[0046] The shell communicating air passage 27 is parallel to the axial direction of the shaft sleeve; the shell communicating air passage 27 is located on the outer shell 2 in the shell;

[0047] The shell communicating air passage 27 is connected with the second communicating air passage 8 to form a closed-loop gas passage;

[0048] Among them, the second gas balancing air chamber 19 is connected with the tail air 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 channel 8 is a vertically flipped L-shape, that is, the second connecting air channel 8 extends to the right side of the impeller tray 4 to communicate with the shell connecting air channel 27.

[0049] In order to prevent the working temperature in the housing 2 from being too high during operation, the housing 2 is provided with a cooling water jacket 35 that wraps the motor stator 5, the first sleeve 16 and the second sleeve 17, and the second gas balance air chamber 19 is formed between the outer side of the right part of the second sleeve 17, the motor and the cooling water jacket 35;

[0050] First sealing rings 37 are installed between the two sides of the outer circumference of the cooling water jacket 35 and the shell for sealing. A first coolant inlet 43 and a first coolant outlet 44 are provided on the shell between the two first sealing rings 37. A spiral cooling groove 45 is provided around the cooling water jacket 35. 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 heat generated by the motor stator 5 and the rotor during operation is absorbed and discharged by the setting of the cooling water jacket 35.

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

[0052] When the compressor is working, the impeller 7 drives the air to form a high-speed airflow, which is decelerated and pressurized after entering the volute 1 to form high-pressure gas. The high-pressure gas passes through the gap between the impeller 7 and the impeller tray 4, the gap between the impeller tray 4 and the rotating shaft 6, the gap between the thrust bearing 11 and the left wall of the cavity 30, the first connecting air channel 10 and the second connecting air channel 8 to communicate with the air path component on the right side of the impeller tray 4. After passing through the second connecting air channel 8, the high-pressure gas enters the annular groove 29 and the radial bearing air cavity respectively. The high-pressure gas enters the thrust air cavity 14 through the annular groove 29 and the circumferential through hole 15 to form a high-pressure air chamber that wraps the thrust plate 12; the high-pressure gas balances the air with the first gas in the radial bearing air cavity through the shaft sleeve inlet 25. The cavity 18 is connected to the second gas balance cavity 19, and then a high-pressure air chamber consistent with the thrust cavity 14 is formed at the position of the rotating shaft 6 through the sleeve vent hole and the annular air groove 23; at the same time, the setting of the tail air cavity 26 will also form a high-pressure air chamber consistent with the thrust cavity 14 at the position of the motor stator 5. At this point, the right side of the impeller tray 4 forms a consistent bearing force on the rotor. When the motor is started or stopped, the existence of the high-pressure air chamber can slow down the friction time and degree of friction between the rotating shaft and the radial bearing and the sleeve of the rotating shaft 6 during start and stop, thereby solving the problem of short service life of air-floating centrifugal air compressors caused by contact and friction between the gas bearing and the sleeve during the start and stop process of the current centrifugal air compressor.

[0053] Example 2

[0054] like Figure 3-Figure 7 and Figure 9-11As shown, the structure of this embodiment is substantially the same as that of embodiment 1. The difference between this embodiment and embodiment 1 is that, in this embodiment, the first communicating air passage 10 is a through hole opened on the impeller tray 4, the left end of the first communicating air passage 10 is communicated with the volute air chamber 52 in the volute 1, the right end of the first communicating air passage 10 is communicated with the shell communicating air passage 27, and a one-way air passage valve 51 is installed on the first communicating air passage 10. When the pressure on the left side of the impeller tray 4 is lower than the pressure in the air passage assembly, the pressure in the air passage assembly is prevented from being released too quickly by installing the one-way air passage valve 51.

[0055] In this embodiment, the first communicating air passage 10 is connected with the tail air chamber 26, the radial bearing air chamber, the second communicating air passage 8 and the thrust air chamber 14 through the housing communicating air passage 27;

[0056] In this embodiment, the second communicating air passage 8 is only provided on the annular inner wall of the cavity 30. The number of the second communicating air passage 8 may be one or more. In this embodiment, the number of the second communicating air passage 8 is four.

[0057] In the present embodiment, after the high-pressure gas enters through the first connecting air passage 10, the high-pressure gas enters the thrust air chamber 14 through the shell 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 for bearing the rotor, thereby forming a consistent bearing force on the rotor. When the motor is started or stopped, the existence of the high-pressure air chamber can slow down the friction time and degree of friction between the rotating shaft 6 and the radial bearing and the sleeve during start and stop, thereby solving the problem of short service life of air-floating centrifugal air compressors caused by contact and friction between the gas bearing and the sleeve during the start and stop process of the current centrifugal air compressor.

[0058] It should be noted that the first radial bearing 21 and the second radial bearing 22 referred to in the present application are both gas bearings described in the background technology.

Claims

1. A low start-stop speed and long life air-floating centrifugal air compressor, characterized in that: The invention comprises a housing and an impeller tray (4) arranged in the housing, a motor stator (5) for driving a rotor to rotate is arranged on the right side of the impeller tray (4), an air path assembly for carrying the rotor is arranged on the right side of the impeller tray (4), the rotor comprises a rotating shaft (6) and an impeller (7) arranged at the end of the rotating 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 path assembly are arranged on the impeller tray (4), the first connecting air passage (10) and the second connecting air passage (8) are connected, the air path assembly comprises a sleeve and two thrust bearings (11) arranged in sequence from right to left and sleeved on the rotating shaft (6), the rotating shaft (6) is provided with a first connecting air passage (10) for connecting the left side of the impeller tray (4) and the air path assembly, the first connecting air passage (10) and the second connecting air passage (8) are connected, the air path assembly comprises a sleeve and two thrust bearings (11) arranged on the rotating shaft (6) in sequence from right to left, A thrust plate (12) and two radial bearings are arranged in sequence on the right side of the impeller plate (4); the thrust plate (12) is located between the two thrust bearings (11); a spacer ring (13) having an inner diameter larger than an outer diameter of the thrust plate (12) is arranged between the two thrust bearings (11); a thrust air cavity (14) is formed between the spacer ring (13) and the thrust plate (12); a circumferential through hole (15) is arranged on the spacer ring (13) for connecting the second connecting air passage (8) with the thrust air cavity (14); a radial bearing balancing air cavity connected to the second connecting air passage (8) or the first connecting air passage (10) is arranged on the shaft sleeve; the circumferential through hole (15) and the radial bearing balancing air cavity are connected via the second connecting air passage (8).

2. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 1, characterized in that: The shaft sleeve comprises a first shaft sleeve (16) sleeved on the rotating shaft (6) and a second shaft sleeve (17) sleeved outside the first shaft sleeve (16); the right part of the second shaft sleeve (17) is interference-connected with the middle part of the first shaft sleeve (16); a first gas balancing air cavity (18) communicating with the first communicating air passage (10) is provided between the left part of the second shaft sleeve (17) and the left part of the first shaft sleeve (16); a second gas balancing air cavity (19) is formed between the right side of the second shaft sleeve (17) and the outer side of the right part of the first shaft sleeve (16); and a shaft sleeve communicating air passage (20) communicating with the first gas balancing air cavity (18) and the second gas balancing air cavity (19) is provided on the second shaft sleeve (17); The two radial bearings include a first radial bearing (21) and a second radial bearing (22) which are arranged in sequence from left to right. Both sides of the first radial bearing (21) and the second radial bearing (22) are provided with an annular gas groove (23). The first shaft sleeve (16) is provided with a shaft sleeve connecting air hole (24) for connecting the annular gas groove (23) with the first gas balancing air cavity (18) and the second gas balancing air cavity (19). The annular gas groove (23) on the right side of the first radial bearing (21) is connected to the first gas balancing air cavity (18) through the shaft sleeve connecting air hole (24), and the annular gas groove (23) on the left side of the second radial bearing (22) is connected to the second gas balancing air cavity (19) through the shaft sleeve connecting air hole (24); the annular gas groove (23) on the left side of the first radial bearing (21) is connected to the first gas balancing air cavity (18), and the annular gas groove (23) on the right side of the second radial bearing (22) is connected to the second gas balancing air cavity (19); The end surface of the second sleeve (17) is connected to the thrust bearing (11) and is provided with a sleeve air inlet (25) connected to the second connecting air channel (8); the first gas balancing air cavity (18) and the second gas balancing air cavity (19) form the radial bearing balancing air cavity.

3. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 2, characterized in that: A tail air cavity (26) is arranged in the shell on the right side of the motor stator (5); the radial bearing balance cavity is connected to the tail air cavity (26); a shell connecting air passage (27) connected to the tail air cavity (26) is arranged on the shell; the shell connecting air passage (27) is connected to the first connecting air passage (10) and / or the second connecting air passage (8).

4. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 2, characterized in that: The number of the circumferential through holes (15) is at least two and they are evenly distributed along the circumference of the spacer ring (13); an annular groove (29) is provided on the outer circumferential surface of the spacer ring (13); the annular groove (29) is connected to the circumferential through hole (15); and the second connecting airway (8) is connected to the annular groove (29).

5. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 1, characterized in that: A cavity (30) for accommodating the two thrust bearings (11) and the end face of the shaft sleeve is arranged on the right side of the impeller tray (4); an annular step (33) is arranged on the inner wall of the cavity (30) connected to the thrust bearing (11); the inner diameter of the annular step (33) is smaller than the inner diameter of the thrust bearing (11); the first connecting air channel (10) is arranged on the annular step (33); the second connecting air channel (8) is arranged on the annular inner wall of the cavity (30) and is connected to the first connecting air channel (10); a cover ring (34) for fixing the shaft sleeve and the two thrust bearings (11) on the impeller tray (4) is arranged in the housing.

6. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 2, characterized in that: A cooling water jacket (35) is provided in the housing and wraps the motor stator (5), the first shaft sleeve (16) and the second shaft sleeve (17); the second gas balancing air cavity (19) is formed on the right side of the second shaft sleeve (17), on the outer side of the right part of the first shaft sleeve (16), between the motor stator (5) and the cooling water jacket (35).

7. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 6, characterized in that: First sealing rings (37) are provided between the shell and both sides of the outer peripheral surface of the cooling water jacket (35); a first cooling liquid inlet (43) and a first cooling liquid outlet (44) are provided on the shell between the two first sealing rings (37); a spiral cooling groove (45) is provided on the cooling water jacket (35); one end of the spiral cooling groove (45) is connected to the first cooling liquid inlet (43); and the other end of the spiral cooling groove (45) is connected to the first cooling liquid outlet (44).

8. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 7, characterized in that: An annular cooling cavity (46) is provided between the cooling water jacket (35) and the second shaft sleeve (17); a second sealing ring (47) for sealing the annular cooling cavity (46) is provided between the cooling water jacket (35) and the second shaft sleeve (17); a second coolant inlet (48) and a second coolant outlet (49) which are in communication with the annular cooling cavity (46) are provided on the cooling water jacket (35); and the second coolant inlet (48) and the second coolant outlet (49) are both in communication with the spiral cooling groove (45).

9. The low start-stop speed and long life air-floating centrifugal air compressor according to claim 1, characterized in that: A one-way airway valve (51) is provided in the first communicating airway (10).

Images