A centrifugal compressor and blower driven by a high speed electric motor

Abstract

The present application relates to a kind of centrifugal compressor and air blower of high-speed motor drive.The problem exists in the prior art: in centrifugal compressor, the leakage compressed gas of 100 ℃-170 ℃ high temperature from the back of impeller of centrifugal compressor can heat bearing, so as to exceed the heat resistance temperature of bearing.For this reason, the prior art adopts the scheme of making bearing away from impeller.As a result, it leads to the length of rotor increases, the critical speed of rotor decreases, the rotor cannot run at high speed, and the output pressure cannot be obtained sufficiently.In order to solve the above problem, the present application adopts the following scheme: setting fin structure, air supply is carried out by fin structure, and the flow of gas at shaft seal is counter-current flow.Thereby, the leakage from shaft seal is prevented, and the heating of bearing by leakage gas is prevented.Finally, the following effects are achieved: the length of rotor is shortened, the critical speed is improved, the running speed is improved, so as to make the running pressure rise, and sufficient output pressure can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a centrifugal compressor and blower driven by a high speed motor. BACKGROUND

[0002] Centrifugal compressors are used as a power source, air source in manufacturing plants. In order to increase the rotational speed of the impeller of the centrifugal compressor, a gear speed increaser has been used in the past. In recent years, a high speed motor has appeared, and a centrifugal compressor (blower) directly driven by the high speed motor has been developed.

[0003] Figure 1 A structure of a centrifugal compressor directly driven by a high speed motor in the prior art is shown. As shown in Figure 1 the centrifugal compressor includes a drive shaft 1, an impeller 2, a scroll casing 3, a diffuser 4, a back casing 5, a shaft seal 6, a bearing 7, a stator 8 and a rotor 9. The drive shaft 1 penetrates a through hole provided in the back casing 5, and the shaft seal 6 such as a labyrinth shaft seal is provided between the drive shaft 1 and the back casing 5. The impeller 2 is fixedly provided at one end of the drive shaft 1 penetrating the back casing 5, and there is a gap between the impeller 2 and the back casing 5 to allow the impeller 2 to rotate. The rotor 9 fixed to the drive shaft 1 is provided at the other end side of the drive shaft 1, and the stator 8 is provided around the rotor 9 with a gap therebetween. In addition, the bearing 7 such as an air bearing or a magnetic bearing is provided on the drive shaft 1 between the shaft seal 6 and the rotor 9. The scroll casing 3 is fixedly connected to the back casing 5 at one end side of the drive shaft 1, and the diffuser 4 is provided inside the scroll casing 3.

[0004] When the centrifugal compressor is operated, the rotor 9 rotates at high speed, and the impeller 2 rotates at high speed by the drive shaft 1, the impeller 2 inhales low temperature and low pressure gas, and delivers high temperature and high pressure gas toward the diffuser 4.

[0005] In such a centrifugal compressor directly driven by a high speed motor, there is a problem as follows. Since there is a gap between the impeller 2 and the back casing 5, as shown by the arrow direction in Figure 1 , part of the high temperature and high pressure gas (100°C to 170°C) enters the gap in the direction of the arrow. Further, since the labyrinth shaft seal 6 and the drive shaft 1 cannot be completely sealed, the part of the high temperature and high pressure gas described above continues to leak through the gap between the shaft seal 6 and the drive shaft 1 toward the bearing 7.

[0006] The leakage compressed gas of high temperature (100°C to 170°C) from the back of the impeller of the centrifugal compressor heats the air bearing and the magnetic bearing, exceeding the heat resistance temperature of the bearing. Generally, about 1% of the high temperature leakage gas is discharged from the impeller of the centrifugal compressor of the high pressure stage in a 7 Bar centrifugal compressor.

[0007] In the related art, in order to prevent the above-mentioned leakage of high-temperature gas from heating the bearing, the length of the drive shaft is generally lengthened to distance the bearing from the shaft seal, and a gap is left between the bearing and the shaft seal to discharge the high-temperature gas into the atmosphere. However, lengthening the length of the drive shaft causes vibration, fluctuation, and a decrease in the critical speed of the rotor, so that the rotor cannot rotate at a high speed. Accordingly, the impeller cannot rotate at a high speed to obtain sufficient output pressure, and ultimately the centrifugal compressor cannot sufficiently work.

[0008] Furthermore, in reality, when the length of the drive shaft is lengthened, in order to cool the surface of the rotor heated by the gas friction loss of the motor rotor, compressed gas cooled by a secondary cooler is used. The gas consumption of the secondary cooler is 14-20%, which deteriorates the overall efficiency. Moreover, as another countermeasure, a dedicated cooling fan is provided, and the consumption power of the fan deteriorates the overall efficiency of the device. SUMMARY

[0009] Based on the above-mentioned defects in the related art, the present application aims to provide a centrifugal compressor capable of greatly reducing the leakage amount of high-temperature gas leaked through the gap between the shaft seal and the drive shaft.

[0010] To this end, the present application provides the following technical solutions.

[0011] The first technical solution of the present application is a centrifugal compressor driven by a high-speed motor, characterized in that the centrifugal compressor includes the following configuration: the centrifugal compressor is provided with a fin structure for sending gas, the fin structure causes the leakage gas leaked from the back surface of the impeller to flow backward toward the gas inlet side of a gas passage, and prevents the leakage gas from leaking through the gap between the shaft seal and the drive shaft, the gas passage is provided in the back surface housing of the centrifugal compressor, and the gas passage is used to discharge the leakage gas from the back surface of the impeller and the gas from the fin structure.

[0012] The second technical solution of the present application is a blower driven by a high-speed motor, characterized in that the blower includes the following configuration: the blower is provided with a fin structure for sending gas, the fin structure causes the leakage gas leaked from the back surface of the impeller to flow backward toward the gas inlet side of a gas passage, and prevents the leakage gas from leaking through the gap between the shaft seal and the drive shaft, the gas passage is provided in the back surface housing of the blower, and the gas passage is used to discharge the leakage gas from the back surface of the impeller and the gas from the fin structure.

[0013] The third technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the first technical solution, characterized in that the centrifugal compressor comprises a back shell, the transmission shaft penetrating through the back shell, the shaft seal arranged between the back shell and the transmission shaft, the impeller arranged at one end of the transmission shaft, and the bearing arranged at the other end side of the transmission shaft, the back shell has a first wall surface opposite to the back surface of the impeller, there is a gap between the first wall surface and the back surface of the impeller, and a gas passage is arranged in the back shell and penetrates through the back shell from the first wall surface.

[0014] The fourth technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the third technical solution, characterized in that the fin structure is arranged at the part of the transmission shaft located at the back surface of the impeller and is mounted at the part of the transmission shaft located between the back surface of the impeller and the shaft seal, the fin structure has a gas suction end located at the shaft seal side and a gas discharge end located at the impeller side, and the gas at the gas suction end is guided to the gas discharge end and is output towards the gap when the fin structure rotates.

[0015] The fifth technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the fourth technical solution, characterized in that the fin structure comprises a mounting disc and fins, the mounting disc is fixedly mounted on the transmission shaft, and the fins are fixedly mounted on the mounting disc.

[0016] The sixth technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the fifth technical solution, characterized in that the fins are multiple, and the multiple fins are uniformly distributed along the circumferential direction of the mounting disc.

[0017] The seventh technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the third technical solution, characterized in that the fin structure is arranged at the back surface of the impeller and is located at the part of the back surface of the impeller closer to the transmission shaft than the gas inlet of the gas passage, the fin structure has a gas suction end located at the transmission shaft side and a gas discharge end located at the gas inlet side, and the gas at the gas suction end is guided to the gas discharge end and is output towards the gas inlet when the fin structure rotates.

[0018] The eighth technical solution of the present application is the centrifugal compressor driven by the high-speed motor or the air blower driven by the high-speed motor according to the seventh technical solution, characterized in that the fin structure comprises a mounting disc and fins, the mounting disc is fixedly mounted on the back surface of the impeller, and the fins are fixedly mounted on the mounting disc.

[0019] The ninth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the eighth technical solution, characterized in that the fins are multiple, and the multiple fins are uniformly distributed along the circumference of the mounting disc.

[0020] The tenth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the seventh technical solution, characterized in that the fin structure comprises fins, and the fins are formed integrally with the impeller.

[0021] The eleventh technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the tenth technical solution, characterized in that the fins are multiple, and the multiple fins are uniformly distributed along the circumference of the impeller.

[0022] The twelfth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the third technical solution, characterized in that the fin structure is arranged at the portion of the transmission shaft opposite to the shaft seal, the fin structure comprises fins, the fins are formed integrally with the transmission shaft, the fin structure has a gas suction end on the bearing side and a gas discharge end on the impeller side, and the gas at the gas suction end is guided to the gas discharge end and output toward the gap when the fin structure rotates.

[0023] The thirteenth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the twelfth technical solution, characterized in that the fins are multiple, and the multiple fins are uniformly distributed along the circumference of the transmission shaft.

[0024] The fourteenth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the third technical solution, characterized in that the gas passage comprises the gas inlet, the gas outlet, and a gas channel connecting the gas inlet and the gas outlet, the gas inlet is located at the portion close to the axis of the transmission shaft in the radial direction, and the gas outlet is located at the portion away from the axis of the transmission shaft in the radial direction.

[0025] The fifteenth technical solution of the present application is the centrifugal compressor driven by a high-speed motor or the air blower driven by a high-speed motor according to the fourteenth technical solution, characterized in that the back shell has a second wall surface toward the side where the bearing is located, the gas inlet is formed in the first wall surface, and the gas outlet is formed in the second wall surface.

[0026] The centrifugal compressor according to the first aspect of the application or the blower according to the second aspect of the application is characterized in that the gas passage is a plurality of gas passages, and the plurality of gas passages are provided at equal intervals in the circumferential direction.

[0027] The centrifugal compressor according to the third aspect of the application or the blower according to the third aspect of the application is characterized in that the first wall surface is provided with an end face seal.

[0028] The centrifugal compressor according to the first aspect of the application or the blower according to the second aspect of the application is characterized in that the centrifugal compressor or the blower further includes a high-speed motor including a stator and a rotor, the rotor is fixedly attached to the drive shaft, the stator is provided around the rotor, and the bearing is located between the rotor and the shaft seal.

[0029] By adopting the above-described technical solution, the centrifugal compressor and the blower driven by a high-speed motor are provided, which can change the flow direction of the leakage gas from the shaft seal to the impeller side, can prevent the heating of the bearing, can shorten the length of the rotor as a whole, can improve the critical speed of the rotor, can improve the operating speed, and can obtain sufficient output pressure. Moreover, the cooling gas of the rotor can be reduced, and thus the overall efficiency can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A structure diagram of a centrifugal compressor in the related art is shown.

[0031] Figure 2 A structure diagram of a centrifugal compressor of the first embodiment of the application is shown.

[0032] Figure 3 A top view of the fin structure of the first embodiment is shown. Figure 2

[0033] Figure 4

[0034] Figure 5 A structure diagram of a centrifugal compressor of the second embodiment of the application is shown.

[0035] Figure 6 A top view of the fin structure of the second embodiment is shown.

[0036] Figure 7 A structure diagram of a centrifugal compressor of the third embodiment of the application is shown. ​​

[0037] Figure 8 The figure shows a top view of the wing structure of the third embodiment.

[0038] Explanation of reference numerals in the attached figures

[0039] 1 Drive shaft; 2 Impeller; 21 Back side; 3 Volute; 31 Inlet; 32 Diffuser flow path; 33 Vortex flow path; 4 Diffuser; 5 Back side shell; 51 First wall; 52 Second wall; 53 Through hole; 54 Gas passage; 541 Inlet; 542 Outlet; 543 Gas channel; 55 End face seal; 6 Shaft seal; 61 Flange; 7 Bearing; 8 Stator; 9 Rotor; 10, 10', 10” Blade structure; 101, 101' Mounting plate; 102, 102', 102” Blade. Detailed Implementation

[0040] Exemplary embodiments of the centrifugal compressor of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only intended to teach those skilled in the art how to implement the invention, and are not intended to exhaustively describe all possible ways of the invention, nor to limit the scope of protection of the invention.

[0041] In this invention, "radial" refers to the direction of the diameter of the drive shaft, "axial" refers to the direction of the central axis of the drive shaft, "circumferential" refers to the direction around the central axis of the drive shaft, and "back side of the impeller" refers to the side of the impeller opposite to the back shell.

[0042] First Implementation Method

[0043] The following is combined with Figures 2-4 The first embodiment of the present invention will be described.

[0044] Figure 2 A structural diagram of a centrifugal compressor according to a first embodiment of the present invention is shown. Figure 3 It shows Figure 2 Enlarged view of the structure of part A in the image. Figure 4 The figure shows a top view of the wing structure of the first embodiment.

[0045] like Figure 2 and Figure 3 As shown, the present invention provides a centrifugal compressor, which includes a drive shaft 1, an impeller 2, a volute 3, a diffuser 4, a back housing 5, a shaft seal 6, a bearing 7, a vane structure 10, and a high-speed motor.

[0046] The transmission shaft 1 penetrates the through hole 53 formed in the center of the back shell 5, and an axial seal 6 such as a labyrinth seal is provided between the transmission shaft 1 and the back shell 5. The other end of the axial seal 6 has a flange portion 61 protruding toward the radial outside in the entire circumferential direction. When the axial seal 6 is arranged between the transmission shaft 1 and the back shell 5, the flange portion 61 abuts against the back surface of the back shell 5. In addition, the specific structure of the labyrinth seal can adopt the conventional design in the art, and the description is omitted here. The axial seal 6 can also be a dry gas seal or a carbon ring seal.

[0047] The impeller 2 is fixedly arranged at the end of the transmission shaft 1 penetrating the back shell 5, and there is a gap between the back surface of the impeller 2 and the back shell 5 to allow the impeller 2 to rotate. Specifically, the end of the transmission shaft 1 penetrates the first central hole formed in the center of the impeller 2, and is tightened from the end of the transmission shaft 1 by using a lock nut, thereby fixing the impeller 2 to the end of the transmission shaft 1. The back surface of the impeller 2 is circular.

[0048] Preferably, the first wall surface 51 is provided with an end face seal 55 arranged opposite to the end of the impeller 2 away from the transmission shaft 1 in the radial direction. The end face seal 55 is annular. In this way, the end face seal 55 can reduce the amount of high-temperature and high-pressure gas entering the above-mentioned gap. Preferably, the end face seal 55 is a labyrinth seal. In addition, the end face seal can also be a dry gas seal or a carbon ring seal.

[0049] A fin structure 10 is arranged in the space between the back surface 21 of the impeller 2 and the other end surface of the axial seal 6 in the through hole 53. The fin structure 10 will be described in detail later.

[0050] The high-speed motor includes a stator 8 and a rotor 9, the stator 8 is arranged around the rotor 9 with a spacing, and the rotor 9 is fixedly installed on the other end side of the transmission shaft 1 opposite to the side where the impeller 2 is located. The high-speed motor drives the transmission shaft 1 to rotate around the central axis of the transmission shaft 1 through the interaction between the stator 8 and the rotor 9.

[0051] In addition, a bearing 7 is arranged on the transmission shaft 1 between the axial seal 6 and the rotor 9. Preferably, the bearing 7 is an air bearing or a magnetic bearing.

[0052] The scroll casing 3 is fixedly arranged on the back shell 5 around the impeller 2, and the scroll casing 3 includes a suction port 31 and a scroll flow path 33, and a diffuser flow path 32 is formed between the scroll casing 3 and the back shell 5. The suction port 31 communicates with the diffuser flow path 32 through the gap between the impeller 2 and the scroll casing 3, and the diffuser flow path 32 communicates with the scroll flow path 33. The diffuser 4 is fixedly arranged on the scroll casing 3 and located in the diffuser flow path 32 for decelerating the gas.

[0053] Next, the structure of the fin structure 10 and the back shell 5 will be described in detail.

[0054] As described above, the fin structure 10 is located in the space between the back surface 21 of the impeller 2 and the other end surface of the shaft seal 6 in the through hole 53, and the fin structure 10 includes a mounting disc 101 and fins 102.

[0055] The mounting disc 1 is in the shape of a curved conical frustum, and the outer lateral surface of the mounting disc 1 is formed as a curved surface that is recessed toward the center line of the mounting disc 1.

[0056] The fins 102 are fixedly arranged on the outer lateral surface of the mounting disc 101. Preferably, the fins 102 are multiple, and are evenly distributed along the circumferential direction of the mounting disc 101. Figure 4 As shown, the fins 102 are evenly distributed along the circumferential direction of the mounting disc 101.

[0057] The fin structure 10 is arranged between the impeller 2 and the shaft seal 6, and is almost accommodated in the through hole 53 of the back surface shell 5. In this way, the structure of the centrifugal compressor can be made compact. The mounting disc 101 is fixed to the back surface 21 of the impeller 2. The mounting disc 101 has a second central hole therein, and the center axis of the second central hole is collinear with the center axis of the first central hole of the impeller 2. The mounting disc 101 is sleeved on the transmission shaft 1 through the second central hole. In this way, the fin structure 10 and the impeller 2 can rotate synchronously around the center axis of the transmission shaft 1 along with the rotation of the transmission shaft 1.

[0058] The fins 102 are configured to extend closer to the transmission shaft 1 as they are closer to the shaft seal 6. One end of the fins 102 closer to the shaft seal 6 is the suction end, and the other end away from the shaft seal 6 is the exhaust end. When the fins 102 rotate, the gas at the suction end can be guided to the exhaust end and output toward the above-mentioned gap. In this way, the movement direction of the gas output from the exhaust end of the fins 102 is opposite to the flow direction of the high-temperature and high-pressure gas in the above-mentioned gap, which can effectively prevent the high-temperature and high-pressure gas from flowing toward the shaft seal 6 and leaking toward the bearing 7 through the gap between the shaft seal 6 and the transmission shaft 1.

[0059] The back surface shell 5 has a first wall surface 51 opposite to the back surface 21 of the impeller 2 and a second wall surface 52 toward the side where the bearing 7 is located. The gas passage 54 and the through hole 53 are formed between the first wall surface 51 and the second wall surface 52. The gas passage 54 penetrates through the back surface shell 5, which will be described in detail later. The through hole 53 is located at the central part of the back surface shell 5, and the transmission shaft 1 penetrates through the through hole 53.

[0060] The gas passage 54 includes a gas inlet 541 opening in the first wall surface 51, a gas outlet 542 opening in the second wall surface 52, and a gas passage 543 between the gas inlet 541 and the gas outlet 542. The gas passage 543 communicates the gas inlet 541 and the gas outlet 542 inside the back housing 5. The gas inlet 541 is arranged at a position close to the axis in the radial direction, and the gas outlet 542 is arranged at a position away from the center of the axis in the radial direction and outside the bearing in the radial direction. Thus, the gas outlet 542 is arranged away from the bearing 7 in the radial direction.

[0061] In the present embodiment, the gas passage 543 preferably extends in a stepped manner, specifically, extends axially from the gas inlet 541, then extends radially inside the back housing 5 perpendicular to the axial direction, and then extends axially toward the gas outlet 542. When the gas passage 543 is formed in a stepped manner, the flow resistance of the gas passage 543 can be increased, so that the gas sucked into the gap between the impeller 2 and the volute 3 can be prevented from leaking from the gas passage 543 in large amounts. However, the gas passage 543 is not limited to this, and can directly communicate the gas inlet 541 and the gas outlet 542 obliquely, as long as the high-temperature and high-pressure gas can be guided from the gas inlet 541 to the gas outlet 542.

[0062] Preferably, the gas passage 54 is provided in plurality, and the plurality of gas passages 54 are arranged at substantially equal intervals in the circumferential direction on the back housing 5. Preferably, the gas inlet 541, the gas outlet 542, and the gas passage 543 each have a circular cross-sectional shape. Preferably, the gas outlet 542 is arranged at a position as far as possible from the center of the axis in the radial direction, so as to be as far as possible from the bearing 7.

[0063] When the centrifugal compressor is in operation, the impeller 2 sucks in gas from the gas suction port 31, and discharges the gas toward the diffuser flow path 32. The gas pressurized by the diffuser flow path 32 enters the scroll flow path 33. Some of the gas discharged from the impeller 2 enters the gap between the back surface 21 of the impeller 2 and the first wall surface 51.

[0064] The gas flow in the structure of the A portion of the centrifugal compressor of the present embodiment will be described below with reference to the arrow marks in FIG. 6. Figure 3 As shown in FIG. 6, the gas sucked into the gap between the back surface 21 of the impeller 2 and the first wall surface 51 of the back housing 5 flows along the back surface 21 of the impeller 2 toward the gas passage 543. The gas flows into the gas passage 543 from the gas inlet 541, and then flows along the gas passage 543 toward the gas outlet 542. The gas flows out of the gas passage 543 from the gas outlet 542, and then flows along the second wall surface 52 of the back housing 5 toward the scroll flow path 33.

[0065] Figure 3 ​As shown, when the centrifugal compressor is working, the high-speed motor drives the transmission shaft 1 to rotate at high speed, which in turn drives the impeller 2 and the vane structure 10 to rotate at high speed. A portion of the high-temperature, high-pressure gas discharged from the high-speed rotating impeller 2 enters the gap between the back surface 21 and the first wall surface 51 of the impeller 2 via the end face seal 55. The high-speed rotating vane structure 10 guides the gas from its intake end to its exhaust end and discharges it towards the aforementioned gap. Because the gas pressure in the aforementioned gap is greater than the gas pressure on the second wall surface 52 side of the back shell 5, the two streams of gas entering the aforementioned gap converge at the inlet 541 of the gas passage 54, enter the gas passage 543 through the inlet 541, and finally exit from the outlet 542. Since the gas from the intake end of the vane structure 10 is guided to the exhaust end, a negative pressure area is formed at the intake end of the vane structure 10, causing the gas on the side where the rotor 9 of the shaft seal 6 is located to flow towards the intake end of the vane structure 10.

[0066] As described above, a small vane structure 10 is provided between the back side of the impeller 2 and the shaft seal 6. During the rotation of the impeller 2, the gas flows in the opposite direction (radially) to the flow direction of the leaking gas leaking from the back side of the impeller 2, thereby preventing the flow of leaking gas leaking from the back side of the impeller 2. Without the vane structure 10, the flow via the shaft seal 6 would flow towards the high-speed motor, but by providing the vane structure 10, the gas can flow towards the impeller 2. Furthermore, in order to suppress the flow of leaking gas from the back side of the impeller 2 as much as possible, an end face seal 55 with a labyrinth seal structure is provided on the back housing 5.

[0067] The leaking gas from the end face seal 55 and the gas from the vane structure 10 merge and are discharged into the external gas through the gas passage 54 in the back housing 5. Thus, by changing the flow direction of the leaking gas from the shaft seal 6 towards the impeller side, heating of the bearing can be prevented, thereby shortening the overall rotor length, increasing the rotor's critical speed, and consequently increasing the operating speed and achieving sufficient output pressure. Furthermore, since the amount of cooling gas required for the rotor can be reduced, overall efficiency can be improved.

[0068] Second Implementation Method

[0069] The following is combined Figures 5-6 The second embodiment of the present invention will be described.

[0070] Figure 5 The diagram shows a structural diagram of a centrifugal compressor according to a second embodiment of the present invention. Figure 6 The figure shows a top view of the wing structure of the second embodiment.

[0071] In the second embodiment of the present application, the wing structure 10' is provided at a surface of the impeller 2 opposite to the first wall surface 51, and is identical to the first embodiment except for the position of the wing structure 10' and the shape and size of the wing structure 10' adjusted to fit the position. The same reference numerals are assigned to the same parts as those of the first embodiment.

[0072] In the second embodiment, the wing structure 10' is provided at a surface of the impeller 2 opposite to the first wall surface 51. The wing structure 10' includes a mounting disk 101' and wings 102'. The mounting disk 101' has a through hole 103' at the center thereof through which the drive shaft 1 penetrates. The mounting disk 101' is mounted to the surface of the impeller 2 opposite to the first wall surface 51, and the wings 102' are arranged at the mounting disk 101' uniformly in the circumferential direction. In this way, the wing structure 10' and the impeller 2 can simultaneously rotate in synchronization with the rotation of the drive shaft 1 about the central axis of the drive shaft 1.

[0073] One end of the wing 102' near the drive shaft 1 is an air intake end, and the other end near the air inlet 541 is an air exhaust end. The wing 102' can guide the gas at the air intake end to the air exhaust end and output toward the air inlet 541 when the wing 102' rotates. In this way, the direction of movement of the gas output from the air exhaust end of the wing 102' is opposite to the direction of flow of the high-temperature and high-pressure gas in the gap described above, and the high-temperature and high-pressure gas can be effectively prevented from flowing toward the shaft seal 6 and leaking toward the bearing 7 through the gap between the shaft seal 6 and the drive shaft 1.

[0074] In addition, as a modification of the second embodiment, the wing 102' can be formed integrally with the back surface of the impeller 2 without the mounting disk 101'. At this time, the wing 102' can be machined by directly cutting the back surface of the impeller 2, or the wing 102' can be fixed to the back surface of the impeller 2 by welding or the like.

[0075] Third Embodiment

[0076] The third embodiment of the present application will be described below with reference to Figures 7-8 The third embodiment of the present application will be described below with reference to

[0077] Figure 7 FIG. 1 is a sectional view showing the structure of a centrifugal compressor according to the third embodiment of the present application, Figure 8 FIG. 2 is a plan view showing the wing structure according to the third embodiment of the present application.

[0078] In the third embodiment of the present application, the wing structure 10" is provided at a surface of the impeller 2 opposite to the first wall surface 51, and is identical to the first embodiment except for the position of the wing structure 10" and the shape and size of the wing structure 10" adjusted to fit the position. The same reference numerals are assigned to the same parts as those of the first embodiment.

[0079] In the third embodiment, the shaft seal 6" only seals most of the gap between the back surface shell 5 and the transmission shaft 1, and there is a larger gap between the shaft seal 6" and the transmission shaft 1 than in the first and second embodiments. The fin structure 10" is provided on the portion of the transmission shaft 1 opposite the shaft seal 6". The fin structure 10" includes fins 102" that are evenly distributed along the circumference of the transmission shaft 1. The fins 102" can be directly cut out of the transmission shaft, or the fins 102" can be fixed to the transmission shaft 1 by welding or the like. That is, in the third embodiment, the fins 102" are integrated with the transmission shaft 1. In this way, the fin structure 10" can rotate with the transmission shaft 1 and synchronously rotate around the central axis of the transmission shaft 1.

[0080] One end of the fin 102" near the bearing 7 is the suction end, and the other end away from the bearing 7 is the exhaust end. When the fin 102" rotates, it can guide the gas at the suction end to the exhaust end and output it toward the gas inlet 541. In this way, the direction of movement of the gas output from the exhaust end of the fin 102" is opposite to the flow direction of the high-temperature and high-pressure gas in the aforementioned gap, effectively preventing the high-temperature and high-pressure gas from flowing toward the shaft seal 6" and leaking through the gap between the shaft seal 6" and the transmission shaft 1 toward the bearing 7.

[0081] By adopting the above technical solutions, the centrifugal compressor according to the present application has at least one of the following advantages:

[0082] (1) In the centrifugal compressor according to the present application, by providing the fin structure on the portion of the transmission shaft located on the back surface of the impeller or on the back surface of the impeller, the leakage of the high-temperature and high-pressure gas in the gap between the back surface of the impeller and the first wall surface of the back surface shell through the gap between the shaft seal and the transmission shaft is effectively inhibited, and further, the adverse consequences of heating on the air bearing are avoided.

[0083] (2) In the centrifugal compressor according to the present application, the gas passage is provided in the back surface shell, which can guide the high-temperature and high-pressure gas in the gap between the back surface of the impeller and the first wall surface of the back surface shell to the side of the back surface shell opposite the impeller, further reducing the leakage amount of the high-temperature and high-pressure gas in the gap through the gap between the shaft seal and the transmission shaft toward the air bearing, and also preventing the adverse consequences of too high gas pressure in the aforementioned gap.

[0084] (3) In the centrifugal compressor of the present application, the leakage amount of high-temperature and high-pressure gas in the gap that leaks through the gap between the shaft seal and the drive shaft toward the air bearing is greatly reduced, so that the air bearing can be disposed close to the shaft seal, and a gap for discharging the high-temperature and high-pressure gas does not need to be reserved between the shaft seal and the air bearing. Accordingly, the length of the drive shaft can be shortened, the critical rotation speed of the rotor is increased, and the rotor can drive the impeller to rotate at a high speed to obtain sufficient output pressure.

[0085] (4) In the centrifugal compressor of the present application, the end face seal is disposed on the first wall surface at an end thereof that is radially apart from the drive shaft, so that the amount of high-temperature and high-pressure gas entering the gap can be reduced, that is, the leakage amount of high-temperature and high-pressure gas in the gap that leaks through the gap between the shaft seal and the drive shaft toward the air bearing can be further reduced.

[0086] (5) Since the cooling gas of the rotor can be reduced, the overall efficiency can be improved.

[0087] The above detailed description of the embodiments of the present application has been given, but it should be further noted that:

[0088] 1. Although the fin structure is fixed to the impeller in the above-described embodiments, the present application is not limited thereto, and the fin structure can be fixed to the drive shaft. The "fixed" mentioned in the present application includes a fixed form of one-piece molding.

[0089] 2. Although the gas outlet of the gas passage is formed in the second wall surface of the back shell in the above-described embodiments, the present application is not limited thereto, and the gas outlet can be formed in the side wall surface of the back shell that is perpendicular to the second wall surface, as long as the high-temperature and high-pressure gas in the gap can be guided to the gas outside the centrifugal compressor.

[0090] 3. Although the shape of the cross section of the gas passage is circular in the above-described embodiments, the present application is not limited thereto, and the shape of the cross section of the gas passage can be polygonal or other irregular shape, and the size of the cross section of the gas passage can be equal everywhere or can be unequal.

[0091] 4. The above description is given by taking the centrifugal compressor as an example, but the present application can also be applied to a case where the axial leakage amount of gas needs to be reduced, including a blower.

[0092] 5. In the above-described embodiments, the example in which the centrifugal compressor is provided on one side of the drive shaft of the high-speed motor is described, but the present application is not limited thereto, and the centrifugal compressor can be provided on both sides of the drive shaft of the high-speed motor.

[0093] In addition, the scope of the protection of the present application is not limited to the specific embodiments in the above described specific embodiments, but as long as the combination of the technical features in the claims of the present application is satisfied, it falls within the scope of the protection of the present application.

Claims

1. A centrifugal compressor driven by a high-speed motor, characterized by comprising a structure in which a vane structure for sending gas is provided, the vane structure reverses the flow of leakage gas that leaks from the back surface of an impeller toward the gas passage side of an intake port, and prevents the leakage gas from leaking from a gap between a shaft seal and a drive shaft, the gas passage is provided in a back surface case of the centrifugal compressor, and the gas passage is used to discharge the leakage gas from the back surface of the impeller and gas from the vane structure, the centrifugal compressor includes a back surface case, the drive shaft that penetrates the back surface case, the shaft seal that is provided between the back surface case and the drive shaft, the impeller that is provided at one end of the drive shaft, and a bearing that is provided at the other end side of the drive shaft, the back surface case has a first wall surface that is opposite the back surface of the impeller, and a gap is present between the first wall surface and the back surface of the impeller, a gas passage is provided in the back surface case, and the gas passage penetrates the back surface case from the first wall surface, the gas passage includes the intake port, an exhaust port, and a gas passage that connects the intake port and the exhaust port, the intake port is located at a position that is close to the axis of the drive shaft in the radial direction, the exhaust port is located at a position that is away from the axis of the drive shaft in the radial direction, and the gas passage extends in a stepped manner, the back surface case has a second wall surface that is toward the bearing, the intake port is provided in the first wall surface, and the exhaust port is provided in the second wall surface, the vane structure is located at a portion of the drive shaft that is opposite the shaft seal or the back surface case.

2. A blower driven by a high-speed motor, characterized by comprising a structure in which a vane structure for sending gas is provided, the vane structure reverses the flow of leakage gas that leaks from the back surface of an impeller toward the gas passage side of an intake port, and prevents the leakage gas from leaking from a gap between a shaft seal and a drive shaft, the gas passage is provided in a back surface case of the blower, and the gas passage is used to discharge the leakage gas from the back surface of the impeller and gas from the vane structure, the blower includes a back surface case, the drive shaft that penetrates the back surface case, the shaft seal that is provided between the back surface case and the drive shaft, the impeller that is provided at one end of the drive shaft, and a bearing that is provided at the other end side of the drive shaft, the back surface case has a first wall surface that is opposite the back surface of the impeller, and a gap is present between the first wall surface and the back surface of the impeller, a gas passage is provided in the back surface case, and the gas passage penetrates the back surface case from the first wall surface, the gas passage includes the intake port, an exhaust port, and a gas passage that connects the intake port and the exhaust port, the intake port is located at a position that is close to the axis of the drive shaft in the radial direction, the exhaust port is located at a position that is away from the axis of the drive shaft in the radial direction, and the gas passage extends in a stepped manner, ​ ​ The back shell has a second wall surface facing the side where the bearing is located, the gas inlet is formed in the first wall surface, and the gas outlet is formed in the second wall surface. The fin structure is located on the portion of the transmission shaft opposite the shaft seal or the back shell.

3. The high-speed motor-driven centrifugal compressor according to claim 1 or the high-speed motor-driven blower according to claim 2, wherein When the fin structure is located on the portion of the transmission shaft opposite the back shell, the fin structure is provided on the portion of the transmission shaft located on the back of the impeller, is installed on the portion of the transmission shaft located between the back of the impeller and the shaft seal, has a gas suction end located on the side of the shaft seal and a gas discharge end located on the side of the impeller, and guides the gas at the gas suction end to the gas discharge end and outputs the gas toward the gap when the fin structure rotates.

4. The high-speed motor-driven centrifugal compressor according to claim 3 or the high-speed motor-driven blower according to claim 3, wherein The fin structure includes a mounting disc and fins, the mounting disc is fixedly installed on the transmission shaft, and the fins are fixedly installed on the mounting disc.

5. The high-speed motor-driven centrifugal compressor according to claim 4 or the high-speed motor-driven blower according to claim 4, wherein The fins are multiple, and the multiple fins are uniformly distributed along the circumference of the mounting disc.

6. The high-speed motor-driven centrifugal compressor according to claim 1 or the high-speed motor-driven blower according to claim 2, wherein When the fin structure is provided on the portion of the transmission shaft opposite the shaft seal, the fin structure includes fins, the fins are formed integrally with the transmission shaft, the fin structure has a gas suction end located on the side of the bearing and a gas discharge end located on the side of the impeller, and guides the gas at the gas suction end to the gas discharge end and outputs the gas toward the gap when the fin structure rotates.

7. The high-speed motor-driven centrifugal compressor according to claim 6 or the high-speed motor-driven blower according to claim 6, wherein The fins are multiple, and the multiple fins are uniformly distributed along the circumference of the transmission shaft.

8. The high-speed motor-driven centrifugal compressor according to claim 1 or the high-speed motor-driven blower according to claim 2, wherein The gas passages are multiple, and the multiple gas passages are arranged at the same interval in the circumferential direction.

9. The high-speed motor-driven centrifugal compressor according to claim 1 or the high-speed motor-driven blower according to claim 2, wherein The first wall surface is provided with an end face seal.

10. The high-speed motor-driven centrifugal compressor according to claim 1 or the high-speed motor-driven blower according to claim 2, wherein Further comprising a high-speed motor including a stator and a rotor, the rotor is fixedly installed on the transmission shaft, the stator is arranged around the rotor, and the bearing is located between the rotor and the shaft seal.

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