Magnetic levitation compressor

Abstract

The present application provides a magnetic levitation compressor. The magnetic levitation compressor comprises a motor main shaft (13), a first impeller (6), a reflow device (4) and an axial displacement sensor (7), wherein the first impeller (6) is installed in the reflow device (4) and sleeved outside the motor main shaft (13), the axial displacement sensor (7) is fixedly arranged relative to the reflow device (4), and the first impeller (6) has an axial detection surface (602) on the side facing the axial displacement sensor (7), and the axial displacement sensor (7) can detect the axial displacement of the first impeller (6) through the axial detection surface (602). According to the magnetic levitation compressor of the present application, the axial position of the impeller can be directly detected, thereby improving the control accuracy of the system.

Description

Technical Field

[0001] The present application relates to the technical field of air compression, and in particular to a magnetic levitation compressor. Background Art

[0002] The impeller pressure ratio of the compressor is generally high, which will cause the compressor rotor to be subjected to a large axial force. In order to reduce the load on the thrust bearing, a balancing disc structure is generally set on the rotor to balance part of the axial force. For magnetic levitation compressors, a balancing disc is also set for the purpose of reducing the axial magnetic bearing load. When controlling the impeller position, magnetic levitation compressors generally use indirect control, which controls the impeller position by controlling a part of the axial component, such as the oil-blocking sleeve.

[0003] The structure of the magnetic suspension centrifugal compressor in the prior art includes a return flow device, a secondary impeller, an oil blocking sleeve, an oil blocking sealing ring, a housing, a displacement sensor, a radial protection structure and a motor main shaft. The secondary impeller and the oil blocking sleeve are installed on the motor main shaft, the oil blocking sleeve sealing ring is fixed on the return flow device, and the displacement sensor is fixed on the housing.

[0004] The compressor uses an oil-blocking sleeve to balance the axial force, and controls the axial position of the oil-blocking sleeve through a displacement sensor, thereby controlling the axial position of the secondary impeller, and the oil-blocking sleeve and the oil-blocking sealing ring form a comb-tooth structure, thereby playing a sealing role. When the compressor is running, the high-speed rotation of the rotor drives the secondary impeller and the oil-blocking sleeve to rotate at high speed, and an air film is formed between the oil-blocking sleeve and the oil-blocking sealing ring to play a sealing role; the axial displacement sensor detects the position of the oil-blocking sleeve, and the front and rear axial bearings control the thrust plate position according to the oil-blocking sleeve position information, thereby controlling the position of the impeller.

[0005] However, since there is a certain axial distance between the impeller and the oil-blocking sleeve, when the compressor is running, the motor shaft will elongate due to the high temperature, causing the relative position of the secondary impeller and the oil-blocking sleeve to change, resulting in errors between the axial sensor detection data and the actual axial position data of the impeller, thereby affecting the control accuracy of the system. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present application is to provide a magnetic levitation compressor that can directly detect the axial position of the impeller and improve the control accuracy of the system.

[0007] In order to solve the above problems, the present application provides a magnetic levitation compressor, including a motor main shaft, a first impeller, a return flow device and an axial displacement sensor. The first impeller is installed in the return flow device and is sleeved outside the motor main shaft. The axial displacement sensor is fixed relative to the return flow device. The first impeller has an axial detection surface on the side facing the axial displacement sensor. The axial displacement sensor can detect the axial displacement of the first impeller through the axial detection surface.

[0008] Preferably, the magnetic levitation compressor further comprises a housing, the main shaft of the motor is installed in the housing, the returner and the housing are fixedly connected, and the axial displacement sensor is installed on the returner or the housing.

[0009] Preferably, the casing or the returner is fixedly mounted with an impeller sealing ring, a mounting groove is provided on the impeller sealing ring, and the axial displacement sensor is mounted in the mounting groove.

[0010] Preferably, a sealing fit is formed between the impeller sealing ring and the first impeller.

[0011] Preferably, a balancing ring is provided on the side of the first impeller facing the axial displacement sensor. The balancing ring extends along the axial direction of the motor main shaft. The balancing ring is sleeved in the impeller sealing ring and is sealed with the impeller sealing ring.

[0012] Preferably, a sawtooth structure is provided on the inner ring surface of the impeller sealing ring, a gap is fitted between the balancing ring and the impeller sealing ring, and an air film gap is formed between the outer ring wall of the balancing ring and the sawtooth structure.

[0013] Preferably, the outer diameter of the back side of the first impeller facing the axial displacement sensor is R1, the outer diameter of the balancing ring is R2, and 1 / 3≤R2 / R1≤2 / 3.

[0014] Preferably, the motor main shaft comprises an inclined shoulder, and the inner annular wall of the first impeller has a conical surface section, which cooperates with the inclined shoulder to limit the axial position of the first impeller relative to the motor main shaft.

[0015] Preferably, a thrust plate is fixedly mounted on the main shaft of the motor, and an axial magnetic bearing is fixedly mounted in the housing. The axial magnetic bearing is arranged on both sides of the thrust plate and defines the axial position of the thrust plate.

[0016] Preferably, a radial magnetic bearing is also provided on the inner wall of the housing.

[0017] The magnetic levitation compressor provided by the present application includes a motor main shaft, a first impeller, a return flow device, an axial displacement sensor and a housing, wherein the motor main shaft is installed in the housing, the return flow device is fixedly connected to the housing, the first impeller is installed in the return flow device and is sleeved outside the motor main shaft, the axial displacement sensor is fixedly arranged relative to the housing, the first impeller has an axial detection surface on the side facing the axial displacement sensor, and the axial displacement sensor can detect the axial displacement of the first impeller through the axial detection surface. The axial displacement sensor of the magnetic levitation compressor is distributed on the back side of the first impeller, and the axial displacement of the first impeller is directly detected by detecting the axial detection surface on the back side of the first impeller, thereby avoiding the problem of inaccurate axial position detection of the impeller caused by the elongation of the axial component due to high temperature during the operation of the compressor, improving the control accuracy of the system, reducing the energy loss between the impeller outlet and the return flow device inlet, and improving the compressor conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A cross-sectional structural diagram of a magnetic levitation compressor according to an embodiment of the present application;

[0019] Figure 2 This is a diagram showing the matching structure of the impeller sealing ring of the magnetic levitation compressor of an embodiment of the present application;

[0020] Figure 3 for Figure 2 The enlarged structure diagram at C;

[0021] Figure 4 A schematic diagram of the forces acting on the first impeller of the magnetic levitation compressor according to an embodiment of the present application;

[0022] Figure 5 This is a schematic diagram of the balancing principle of the first impeller of the magnetic levitation compressor according to an embodiment of the present application.

[0023] The reference numerals are as follows:

[0024] 1. Second impeller; 2. Second impeller diffuser; 3. First-stage diffuser; 4. Return flow meter; 5. Interstage seal support ring; 6. First impeller; 7. Axial displacement sensor; 8. Impeller seal ring; 9. Casing; 10. First radial protection structure; 11. First radial magnetic bearing; 12. Motor stator; 13. Motor main shaft; 14. Second radial magnetic bearing; 15. Second radial protection structure; 16. First axial magnetic bearing; 17. Thrust plate; 18. Second axial magnetic bearing; 601. Balance ring; 602. Axial detection surface. DETAILED DESCRIPTION

[0025] See also Figures 1 to 5As shown, according to an embodiment of the present application, the magnetic levitation compressor includes a motor main shaft 13, a first impeller 6, a return flow device 4, an axial displacement sensor 7 and a housing 9, the motor main shaft 13 is installed in the housing 9, the return flow device 4 and the housing 9 are fixedly connected, the first impeller 6 is installed in the return flow device 4, and is sleeved on the outside of the motor main shaft 13, the axial displacement sensor 7 is fixedly arranged relative to the housing 9, and the first impeller 6 has an axial detection surface 602 on the side facing the axial displacement sensor 7, and the axial displacement sensor 7 can detect the axial displacement of the first impeller 6 through the axial detection surface 602.

[0026] The axial displacement sensor 7 of the magnetic levitation compressor is distributed on the back side of the first impeller 6, and the axial displacement of the first impeller 6 is directly detected by detecting the axial detection surface 602 on the back side of the first impeller 6, thereby avoiding the problem of inaccurate axial position detection of the impeller due to the elongation of the axial component due to high temperature during the operation of the compressor, thereby improving the control accuracy of the system, reducing the energy loss between the impeller outlet and the return inlet, and improving the compressor conversion efficiency. The above-mentioned magnetic levitation compressor is, for example, a magnetic levitation centrifugal compressor.

[0027] The axial displacement sensor 7 is installed on the return flow device 4 or the housing 9, so that the axial displacement sensor 7 can be in a fixed state and will not change with the extension or shortening of the motor main shaft 13, so the axial displacement of the first impeller 6 can be accurately detected.

[0028] The housing 9 or the return flow device 4 is fixedly mounted with an impeller sealing ring 8, and a mounting groove is provided on the impeller sealing ring 8, and the axial displacement sensor 7 is mounted in the mounting groove. In this embodiment, the axial displacement sensor 7 is mounted on the impeller sealing ring 8, so that the axial displacement sensor 7 and the impeller sealing ring 8 can form an integrated structure, thereby reducing the axial size of the compressor and making the overall structure of the compressor more compact. The impeller sealing ring 8 can also be fixedly connected to the return flow device 4 and the housing 9 at the same time.

[0029] The axial displacement sensor 7 is fixed on the impeller sealing ring 8, and the connection methods include but are not limited to screws, bolts, pin connections, interference fit thermal assembly, welding, adhesive application, etc. In this embodiment, a mounting groove is provided on the side of the impeller sealing ring 8 facing the return flow device 4, and the axial displacement sensor 7 is provided on the side of the impeller sealing ring 8 facing the return flow device 4, so as to more conveniently realize the fixed installation of the axial displacement sensor 7.

[0030] A sealing fit is formed between the impeller sealing ring 8 and the first impeller 6, and the sealing fit between the impeller sealing ring 8 and the first impeller 6 can replace the face-to-face fit between the oil-blocking sleeve and the impeller sealing ring 8, thereby eliminating the oil-blocking sleeve, reducing the number of parts, and reducing the weight of the rotor assembly, thereby improving the operating stability of the compressor.

[0031] A balancing ring 601 is provided on the side of the first impeller 6 facing the axial displacement sensor 7 . The balancing ring 601 extends along the axial direction of the motor main shaft 13 . The balancing ring 601 is sleeved in the impeller sealing ring 8 and is sealed with the impeller sealing ring 8 .

[0032] A sawtooth structure is arranged on the inner ring surface of the impeller sealing ring 8, and a gap is fitted between the balancing ring 601 and the impeller sealing ring 8, and an air film gap is formed between the outer ring wall of the balancing ring 601 and the sawtooth structure.

[0033] The serrated structure of the impeller sealing ring 8 is not limited to triangular serrations, rectangular serrations, etc., and can generate an air film when the balancing ring 601 on the first impeller 6 and the impeller sealing ring 8 rotate at a relatively high speed, thereby blocking the flow of gas; the first impeller 6 is a rotating body, and the impeller sealing ring 8 is a non-rotating body, so a gap fit is adopted between the balancing ring 601 and the impeller sealing ring 8 to avoid friction between the balancing ring 601 and the impeller sealing ring 8 during the rotation of the first impeller 6, thereby avoiding wear and tear.

[0034] The outer diameter of the back side of the first impeller 6 facing the axial displacement sensor 7 is R1, and the outer diameter of the balancing ring is R2, 1 / 3≤R2 / R1≤2 / 3. The balancing ring 601 can balance the axial forces at both ends of the first impeller 6, and improve the stability of the first impeller 6 during operation. The inner diameter of the balancing ring 601 is larger than the inner diameter of the first impeller 6, and the outer diameter of the balancing ring 601 is smaller than the outer diameter of the back side of the first impeller 6. The back side of the first impeller 6 refers to the side of the first impeller 6 facing the impeller sealing ring 8. Preferably, when the balancing ring 601 is located within the range of 1 / 3-2 / 3 of the outer diameter of the first impeller 6, the effect of balancing the axial force is best.

[0035] The motor main shaft 13 includes an oblique shoulder, and the inner annular wall of the first impeller 6 has a conical surface section, which cooperates with the oblique shoulder to limit the axial position of the first impeller 6 relative to the motor main shaft 13. The oblique shoulder is used between the motor main shaft 13 and the first impeller 6, which can facilitate the axial positioning of the first impeller 6 on the motor main shaft 13.

[0036] A thrust plate 17 is fixedly mounted on the motor main shaft 13, and an axial magnetic bearing is fixedly mounted in the housing 9. The axial magnetic bearing is arranged on both sides of the thrust plate 17 and defines the axial position of the thrust plate 17. In this embodiment, the axial magnetic bearing includes a first axial magnetic bearing 16 arranged on a first side of the thrust plate 17 and a second axial magnetic bearing 18 arranged on a second side of the thrust plate 17, which can exert an axial force on the thrust plate 17 from both sides of the thrust plate 17 to adjust the axial position of the thrust plate 17, thereby adjusting the axial position of the motor main shaft 13.

[0037] A radial magnetic bearing is also provided on the inner wall of the housing 9. In this embodiment, a first radial magnetic bearing 11 is provided at the first end of the housing 9, and a second radial magnetic bearing 14 is provided at the second end of the housing 9, so that radial magnetic suspension can be applied to the motor shaft 13 from both ends of the motor shaft 13, making it easier to achieve radial balance of the motor shaft 13.

[0038] A first radial protection structure 10 is provided on the inner wall of the first end of the shell 9, and a second radial protection structure 15 is provided on the inner wall of the second end of the shell 9, which can form radial protection at both ends of the motor shaft 13 to avoid the problem of damage to the motor shaft 13 due to failure of the magnetic bearing.

[0039] A motor stator 12 is also fixedly mounted on the inner wall of the housing 9 . The motor stator 12 can cooperate with a rotor assembly on the motor main shaft 13 to provide a force for the motor main shaft 13 to rotate.

[0040] The magnetic levitation compressor also includes a second impeller 1, a second impeller diffuser 2, a first-stage diffuser 3 and an interstage sealing support ring 5, wherein the second impeller 1 is installed on the inner side of the second impeller diffuser 2 and is fixedly installed on the first end portion of the motor main shaft 13, the first-stage diffuser 3 is arranged between the air outlet of the second impeller 1 and the air inlet of the first impeller 6, and the gas at the air outlet of the second impeller 1 is diffused and then sent to the air inlet of the first impeller 6, the interstage sealing support ring 5 is sleeved on the outside of the motor main shaft 13, and the first-stage diffuser 3 is sleeved on the interstage sealing support ring 5.

[0041] The working process of the above-mentioned magnetic suspension compressor is as follows:

[0042] When the magnetic levitation compressor is running, the motor main shaft 13 rotates at high speed, driving the first impeller 6 to rotate, and an air film is formed between the impeller sealing ring 8 and the balance ring 601, so that the gas in the cavity of the reflux device 4 is sealed and isolated from the gas in the motor cavity, thereby playing a sealing role. The first impeller 6 works, so that the primary air pressure P1, the secondary air pressure P2 and the cavity air pressure P3 produce a pressure difference. The first impeller 6 is subjected to axial pressures of P1*S1, P2*(S2-S3) and P3*S4. At this time, the balance ring 601 has an optimal position, which can better achieve the axial force balance of the first impeller 6. After research, it was found that when the balance ring 601 is located in the range of 1 / 3-2 / 3 of the back outer diameter of the first impeller 6, the impeller axial force is zero, and the balance ring 601 plays a role in balancing the axial force. The axial displacement sensor 7 monitors the axial position of the first impeller 6 in real time. The first axial magnetic bearing 16 and the second axial magnetic bearing 18 control the position of the thrust plate 17 according to the data collected by the axial displacement sensor 7, thereby driving the first impeller 6 to move, thereby realizing real-time control of the position of the first impeller 6.

[0043] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0044] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A magnetic levitation compressor, characterized in that: The invention comprises a motor main shaft (13), a first impeller (6), a return flow device (4) and an axial displacement sensor (7), wherein the first impeller (6) is installed in the return flow device (4) and sleeved outside the motor main shaft (13), the axial displacement sensor (7) is fixedly arranged relative to the return flow device (4), and the first impeller (6) has an axial detection surface (602) on a side facing the axial displacement sensor (7), and the axial displacement sensor (7) can detect the axial displacement of the first impeller (6) through the axial detection surface (602); The magnetic levitation compressor further comprises a housing (9), the motor main shaft (13) is mounted in the housing (9), the returner (4) and the housing (9) are fixedly connected, and the axial displacement sensor (7) is mounted on the returner (4) or the housing (9); The housing (9) or the return flow device (4) is fixedly mounted with an impeller sealing ring (8), the impeller sealing ring (8) is provided with a mounting groove, and the axial displacement sensor (7) is mounted in the mounting groove; A balancing ring (601) is provided on a side of the first impeller (6) facing the axial displacement sensor (7); the balancing ring (601) extends along the axial direction of the motor main shaft (13); the balancing ring (601) is sleeved inside the impeller sealing ring (8) and is in sealing cooperation with the impeller sealing ring (8); The outer diameter of the back side of the first impeller (6) facing the axial displacement sensor (7) is R1, the outer diameter of the balancing ring is R2, and 1 / 3≤R2 / R1≤2 / 3; The motor main shaft (13) comprises an inclined shoulder, and the inner annular wall of the first impeller (6) comprises a conical surface section, and the conical surface section cooperates with the inclined shoulder to limit the axial position of the first impeller (6) relative to the motor main shaft (13).

2. The magnetic levitation compressor according to claim 1, characterized in that: A sealing fit is formed between the impeller sealing ring (8) and the first impeller (6).

3. The magnetic levitation compressor according to claim 1, characterized in that: A sawtooth structure is provided on the inner ring surface of the impeller sealing ring (8); a clearance fit is formed between the balancing ring (601) and the impeller sealing ring (8); and an air film gap is formed between the outer ring wall of the balancing ring (601) and the sawtooth structure.

4. The magnetic levitation compressor according to claim 1, characterized in that: A thrust plate (17) is fixedly mounted on the motor main shaft (13), and an axial magnetic suspension bearing is fixedly mounted in the housing (9). The axial magnetic suspension bearing is arranged on both sides of the thrust plate (17) and defines the axial position of the thrust plate (17).

5. The magnetic levitation compressor according to claim 1, characterized in that: A radial magnetic bearing is also provided on the inner wall of the housing (9).

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