Centrifugal compressor

Abstract

To actualize efficient cooling of a magnetic substance by using fluid flowing in a gap between a stator and a rotor.SOLUTION: A centrifugal compressor 10 includes a nozzle 73 for generating a swirl flow of air on the upstream side in the flowing direction of air further than a gap G1 between a stator 32 and a rotor 33, and a communication path 80 for making the swirl flow of air generated by the nozzle 73 move into the gap G1. Accordingly, the swirl flow of air generated by the nozzle 73 moves into the gap G1 between the stator 32 and the rotor 33 via the communication path 80, and so the swirl flow of air moving into the gap G1 assists the rotation of the rotor 33. As the result, the mechanical loss of the rotor 33, that is, windage loss is hardly caused, thus suppressing a temperature rise due to the windage loss of air flowing in the gap G1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a centrifugal compressor. [Background technology]

[0002] The centrifugal compressor includes a rotor including a rotating shaft and an impeller. The impeller rotates integrally with the rotating shaft to compress the fluid. The centrifugal compressor includes a motor and a housing. The motor rotates the rotating shaft. The housing has a motor chamber. The motor chamber accommodates the motor. The motor includes a cylindrical stator and a rotor. The stator is fixed to the housing. The rotor rotates integrally with the rotating shaft. The rotor is disposed inside the stator. The rotor constitutes a part of the rotor. The rotor has a magnetic body.

[0003] In such a centrifugal compressor, eddy currents are generated in the magnetic body, which generates heat. Therefore, it has been considered to cool the magnetic body, for example, as in Patent Document 1. The housing has an inlet passage and a discharge passage. The inlet passage introduces a part of the fluid compressed with the rotation of the impeller into the motor chamber. The discharge passage discharges the fluid introduced from the inlet passage into the motor chamber and passed through the gap between the stator and the rotor to the outside of the housing. Then, the magnetic body is cooled by the fluid passing through the gap between the stator and the rotor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-43236 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such a centrifugal compressor, when the rotor rotates at high speed, the speed of the fluid flowing through the gap between the stator and the rotor increases. This increase in the fluid speed due to the high speed rotation of the rotor occurs due to the increase in resistance caused by friction between the outer circumferential surface of the rotor and the fluid. As a result, mechanical loss of the rotor, so-called "windage loss", occurs. This causes the temperature of the fluid flowing through the gap between the stator and the rotor to increase. As a result, there is a risk that the magnetic body cannot be efficiently cooled by the fluid flowing through the gap between the stator and the rotor. [Means for solving the problem]

[0006] A centrifugal compressor that solves the above problem includes a rotor including a rotating shaft and an impeller that rotates integrally with the rotating shaft to compress a fluid, a motor that rotates the rotating shaft, and a housing having a motor chamber that accommodates the motor. The motor includes a cylindrical stator fixed to the housing, and a rotor that rotates integrally with the rotating shaft and is disposed inside the stator and forms a part of the rotor. The rotor has a magnetic body. The housing includes an introduction passage that introduces a part of the fluid compressed as the impeller rotates into the motor chamber, and a discharge passage that discharges the fluid that has been introduced from the introduction passage into the motor chamber and passed through a gap between the stator and the rotor to the outside of the housing. The centrifugal compressor is configured such that the magnetic body is cooled by the fluid that passes through the gap. The centrifugal compressor includes a nozzle that generates a swirling flow of the fluid upstream of the gap in the flow direction of the fluid, and a communication passage that allows the swirling flow of the fluid generated by the nozzle to flow into the gap.

[0007] According to this, the swirling flow of the fluid generated by the nozzle flows into the gap between the stator and the rotor through the communication passage, and the swirling flow of the fluid that flows into the gap between the stator and the rotor assists the rotation of the rotor. As a result, mechanical loss of the rotor, so-called "windage loss", is less likely to occur. Therefore, the temperature rise due to windage loss of the fluid flowing through the gap between the stator and the rotor can be suppressed. The average temperature of the fluid flowing through the gap between the stator and the rotor can be reduced by the amount of the temperature rise due to windage loss suppressed. As a result, the magnetic body can be efficiently cooled by the fluid flowing through the gap between the stator and the rotor.

[0008] In the above centrifugal compressor, the stator may have a stator core and a coil end that is a part of a coil wound around the stator core and protrudes from an end face of the stator core, and the nozzle may be located upstream of the gap in the flow direction of the fluid and radially inward of the coil end of the rotating shaft.

[0009] According to this, a swirling flow of the fluid can be generated by the nozzle just before the fluid flows into the gap between the stator and the rotor. Therefore, the swirling flow of the fluid can be caused to flow into the gap between the stator and the rotor while suppressing the pressure loss of the swirling flow of the fluid. As a result, it is possible to further easily suppress the temperature rise of the fluid flowing through the gap between the stator and the rotor, and therefore the magnetic body can be cooled more efficiently by the fluid flowing through the gap between the stator and the rotor.

[0010] In the centrifugal compressor, the stator may include a resin for molding the stator core, the resin having an end face covering portion for covering a portion of an end face of the stator core located radially inward of the coil ends of the rotating shaft, the resin having a plurality of nozzle vanes protruding from the end face covering portion and arranged in a circumferential direction around the axis of the rotating shaft, the nozzle vanes having a downstream edge located downstream in the fluid flow direction being closer to the gap than an upstream edge located upstream in the fluid flow direction and curved to be located on the leading side in the rotation direction of the rotating shaft, and the nozzles may be formed by gaps between adjacent nozzle vanes in the circumferential direction of the rotating shaft. Such a configuration is suitable for forming nozzles located upstream of the gap in the fluid flow direction and radially inward of the coil ends of the rotating shaft.

[0011] In the centrifugal compressor, the housing may have a facing portion that faces a portion of the end face of the stator core that is located radially inward of the rotating shaft relative to the coil ends in the axial direction of the rotating shaft, and may include a plurality of nozzle vanes that protrude from the facing portion and are arranged side by side in the circumferential direction around the axis of the rotating shaft, the nozzle vanes have a downstream edge that is located downstream in the fluid flow direction and is closer to the gap than the upstream edge that is located upstream in the fluid flow direction and is curved to be located on the leading side in the rotation direction of the rotating shaft, and the nozzles may be formed by gaps between adjacent nozzle vanes in the circumferential direction of the rotating shaft. This configuration is suitable for forming nozzles that are located upstream of the gap in the fluid flow direction and radially inward of the coil ends of the rotating shaft.

[0012] In the centrifugal compressor, the downstream end of the introduction passage located on the motor chamber side is formed to be smaller than a flow path cross-sectional area located upstream of the downstream end in the fluid flow direction, thereby forming the nozzle, and the introduction direction of the fluid from the nozzle into the motor chamber is preferably set to be a circumferential direction of the rotating shaft.

[0013] According to this, the fluid is introduced into the motor chamber from the introduction passage in a state where a swirling flow of the fluid is generated by the nozzle. Then, the swirling flow of the fluid introduced into the motor chamber from the introduction passage can be caused to flow into the gap between the stator and the rotor via the communication passage. Effect of the Invention

[0014] According to this invention, the magnetic body can be efficiently cooled by the fluid flowing through the gap between the stator and the rotor. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of a centrifugal compressor according to an embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of the centrifugal compressor. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing a portion of the centrifugal compressor. [Figure 4] FIG. 4 is a perspective view for explaining the nozzle. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing a part of a centrifugal compressor in a modified example. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a part of a centrifugal compressor in a modified example. [Figure 7] FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, a centrifugal compressor according to one embodiment will be described with reference to Figures 1 to 4. The centrifugal compressor of this embodiment is mounted on a fuel cell vehicle. The centrifugal compressor compresses air as a fluid.

[0017] <Basic configuration of a centrifugal compressor> As shown in Fig. 1, the centrifugal compressor 10 includes a housing 11. The housing 11 is made of a metal material. For example, the housing 11 is made of aluminum. The housing 11 is cylindrical. The housing 11 includes a motor housing 12, a first compressor housing 13, a second compressor housing 14, a first plate 15, a second plate 16, and a seal plate 17.

[0018] The motor housing 12 is cylindrical. The motor housing 12 has a plate-shaped end wall 12a and a peripheral wall 12b. The peripheral wall 12b extends cylindrically from the outer periphery of the end wall 12a. The first plate 15 is connected to an end of the peripheral wall 12b of the motor housing 12 on the opening side. The first plate 15 closes the opening of the peripheral wall 12b of the motor housing 12. A motor chamber 18 is defined by the end wall 12a and the peripheral wall 12b of the motor housing 12 and the first plate 15. Thus, the housing 11 has the motor chamber 18.

[0019] The first plate 15 has a first recess 15a and a second recess 15b. The first recess 15a and the second recess 15b are formed on an end surface of the first plate 15 located on the opposite side to the motor housing 12. The first recess 15a and the second recess 15b are circular holes. The inner diameter of the first recess 15a is larger than the inner diameter of the second recess 15b. The second recess 15b is formed on the bottom surface of the first recess 15a. The axis of the first recess 15a and the axis of the second recess 15b are aligned.

[0020] The seal plate 17 is fitted into the first recess 15a. The seal plate 17 is attached to the first plate 15 by, for example, bolts (not shown). The seal plate 17 closes the opening of the second recess 15b. A thrust bearing accommodating chamber 19 is defined by the seal plate 17 and the second recess 15b. Therefore, the housing 11 has the thrust bearing accommodating chamber 19. The seal plate 17 also has a shaft insertion hole 17h. The shaft insertion hole 17h is formed in the center of the seal plate 17. The shaft insertion hole 17h opens into the thrust bearing accommodating chamber 19.

[0021] The first plate 15 has a first radial bearing retaining portion 21. The first radial bearing retaining portion 21 is cylindrical. The first radial bearing retaining portion 21 protrudes into the motor chamber 18 from the center of the end face of the first plate 15 located on the motor housing 12 side. The inside of the first radial bearing retaining portion 21 communicates with the motor chamber 18. The inside of the first radial bearing retaining portion 21 penetrates the first plate 15 and opens to the bottom face of the second recess 15b. Therefore, the inside of the first radial bearing retaining portion 21 communicates with the thrust bearing accommodating chamber 19. The axis of the first radial bearing retaining portion 21 coincides with the axis of the first recess 15a and the axis of the second recess 15b.

[0022] The first compressor housing 13 is cylindrical. The first compressor housing 13 has a first suction port 22 in the shape of a circular hole. Therefore, the housing 11 has the first suction port 22. The first compressor housing 13 is connected to an end face of the first plate 15 located on the opposite side to the motor housing 12, with the axis of the first suction port 22 coinciding with the axis of the shaft insertion hole 17h of the seal plate 17. The first suction port 22 opens to an end face of the first compressor housing 13 located on the opposite side to the first plate 15. Air cleaned by an air cleaner (not shown) flows through the first suction port 22.

[0023] The centrifugal compressor 10 includes a first impeller chamber 23, a first discharge chamber 24, and a first diffuser passage 25. The first impeller chamber 23, the first discharge chamber 24, and the first diffuser passage 25 are formed between the first compressor housing 13 and the seal plate 17. Thus, the housing 11 includes the first impeller chamber 23. The seal plate 17 separates the first impeller chamber 23 from the thrust bearing accommodating chamber 19. The first impeller chamber 23 communicates with the first suction port 22. The first impeller chamber 23 has a generally truncated cone shape that gradually expands in diameter as it moves away from the first suction port 22. The first discharge chamber 24 extends around the axis of the first suction port 22 around the first impeller chamber 23. The first diffuser passage 25 communicates the first impeller chamber 23 and the first discharge chamber 24. The first impeller chamber 23 communicates with the shaft insertion hole 17 h of the seal plate 17 .

[0024] The motor housing 12 has a second radial bearing retaining portion 26. The second radial bearing retaining portion 26 is cylindrical. The second radial bearing retaining portion 26 protrudes from the center of the inner surface of the end wall 12a of the motor housing 12 into the motor chamber 18. The inside of the second radial bearing retaining portion 26 communicates with the motor chamber 18. The inside of the second radial bearing retaining portion 26 penetrates the end wall 12a of the motor housing 12 and opens to the outer surface of the end wall 12a. The axis of the first radial bearing retaining portion 21 and the axis of the second radial bearing retaining portion 26 are aligned.

[0025] The second plate 16 is connected to the outer surface of the end wall 12a of the motor housing 12. The second plate 16 has a shaft insertion hole 16h. The shaft insertion hole 16h is formed in the center of the second plate 16. The shaft insertion hole 16h communicates with the inside of the second radial bearing holder 26.

[0026] The second compressor housing 14 is cylindrical. The second compressor housing 14 has a second suction port 27 in the form of a circular hole. The second compressor housing 14 is connected to an end face of the second plate 16 located on the opposite side to the motor housing 12, with the axis of the second suction port 27 coinciding with the axis of the shaft insertion hole 16h of the second plate 16. The second suction port 27 opens into an end face of the second compressor housing 14 located on the opposite side to the second plate 16.

[0027] The centrifugal compressor 10 includes a second impeller chamber 28, a second discharge chamber 29, and a second diffuser passage 30. The second impeller chamber 28, the second discharge chamber 29, and the second diffuser passage 30 are formed between the second compressor housing 14 and the second plate 16. The second impeller chamber 28 communicates with the second suction port 27. The second discharge chamber 29 extends around the axis of the second suction port 27 around the periphery of the second impeller chamber 28. The second diffuser passage 30 communicates with the second impeller chamber 28 and the second discharge chamber 29. The second impeller chamber 28 communicates with the shaft insertion hole 16h of the second plate 16.

[0028] The centrifugal compressor 10 includes a motor 31. The motor 31 is accommodated in the motor chamber 18. Therefore, the motor chamber 18 accommodates the motor 31. The motor 31 is accommodated in the housing 11.

[0029] The motor 31 includes a cylindrical stator 32 and a rotor 33. The stator 32 includes a cylindrical stator core 34 and a coil 35. The coil 35 is wound around the stator core 34. The stator core 34 is fixed to the inner circumferential surface of the peripheral wall 12b of the motor housing 12. Thus, the stator 32 is fixed to the housing 11. Coil ends 36, which are part of the coil 35, protrude from both end faces of the stator core 34. Thus, the stator 32 has coil ends 36, which are part of the coil 35 and protrude from the end faces of the stator core 34. In the following description, the coil ends 36 located on the first plate 15 side of the stator core 34 will be referred to as "first coil ends 36a". Furthermore, the coil ends 36 located on the end wall 12a side of the motor housing 12 of the stator core 34 will be referred to as "second coil ends 36b".

[0030] 2, the stator 32 includes a resin 37. The resin 37 covers the stator core 34 and the coil ends 36. Thus, the resin 37 molds the stator core 34.

[0031] The resin 37 has a first resin portion 38, a second resin portion 39, and a third resin portion 40. The first resin portion 38 is cylindrical and covers the first coil end 36a with resin. The first resin portion 38 covers an end face of the stator core 34 located on the first plate 15 side. The second resin portion 39 is cylindrical and covers the second coil end 36b with resin. The second resin portion 39 covers an end face of the stator core 34 located on the end wall 12a side of the motor housing 12. The third resin portion 40 is cylindrical and covers the inner peripheral surface of the stator core 34 with resin. The third resin portion 40 extends in the axial direction of the stator core 34 inside the stator core 34. The third resin portion 40 connects the first resin portion 38 and the second resin portion 39.

[0032] The rotor 33 is disposed inside the stator 32. The rotor 33 has a cylindrical member 41 and a permanent magnet 42 which is a magnetic body. The cylindrical member 41 is made of, for example, a titanium alloy. The cylindrical member 41 is cylindrical with the axis of the cylindrical member 41 extending linearly. The outer diameter of the cylindrical member 41 is constant. The cylindrical member 41 passes through the inside of the third resin part 40. The space between the outer peripheral surface of the cylindrical member 41 and the inner peripheral surface of the third resin part 40 forms a gap G1 between the stator 32 and the rotor 33.

[0033] The permanent magnet 42 has a cylindrical shape. The permanent magnet 42 is disposed inside the cylindrical member 41. The axis of the permanent magnet 42 coincides with the axis of the cylindrical member 41. The permanent magnet 42 is press-fitted into the inner circumferential surface of the cylindrical member 41. Therefore, the permanent magnet 42 is fixed inside the cylindrical member 41. The permanent magnet 42 is magnetized in the radial direction of the permanent magnet 42. Specifically, the permanent magnet 42 is magnetized in the radial direction of the permanent magnet 42, so that the permanent magnet 42 has a cylindrical shape having an N pole and an S pole on both sides of the radial direction of the permanent magnet 42.

[0034] The length of the permanent magnet 42 in the axial direction is shorter than the length of the tubular member 41 in the axial direction. Both end faces of the permanent magnet 42 are located inside the tubular member 41. Therefore, both end portions located in the axial direction of the tubular member 41 protrude in the axial direction relative to both end faces of the permanent magnet 42. And, both end portions of the tubular member 41 protrude in the axial direction relative to both end faces of the stator core 34.

[0035] 1, the centrifugal compressor 10 includes a rotating shaft 43. The rotating shaft 43 includes a first shaft member 44 and a second shaft member 45. The first shaft member 44 and the second shaft member 45 are provided on both sides of the permanent magnet 42 in the axial direction of the cylindrical member 41. The first shaft member 44 and the second shaft member 45 are made of, for example, iron.

[0036] A first end of the first shaft member 44 is press-fitted into the inner circumferential surface of the first end of the cylindrical member 41. Therefore, the first shaft member 44 is fixed to the cylindrical member 41. A second end of the first shaft member 44 protrudes from the motor chamber 18 into the first impeller chamber 23, passing through the inside of the first radial bearing holder 21, the thrust bearing accommodating chamber 19, and the shaft insertion hole 17h.

[0037] A first end of the second shaft member 45 is press-fitted into the inner circumferential surface of the second end of the cylindrical member 41. Therefore, the second shaft member 45 is fixed to the cylindrical member 41. The second end of the second shaft member 45 passes from the motor chamber 18 to the inside of the second radial bearing holder 26 and through the shaft insertion hole 16h, and protrudes into the second impeller chamber 28.

[0038] The axis of the cylindrical member 41, the axis of the first shaft member 44, and the axis of the second shaft member 45 are aligned. The axial direction of each of the cylindrical member 41, the first shaft member 44, and the second shaft member 45 is the axial direction of the rotating shaft 43. The direction perpendicular to the axial direction of the rotating shaft 43 is the radial direction of the rotating shaft 43.

[0039] The centrifugal compressor 10 includes a first seal member 46. The first seal member 46 is provided between the shaft insertion hole 17h of the seal plate 17 and the first shaft member 44. The first seal member 46 suppresses air leakage from the first impeller chamber 23 toward the motor chamber 18. The centrifugal compressor 10 includes a second seal member 47. The second seal member 47 is provided between the shaft insertion hole 16h of the second plate 16 and the second shaft member 45. The second seal member 47 suppresses air leakage from the second impeller chamber 28 toward the motor chamber 18. The first seal member 46 and the second seal member 47 are, for example, seal rings.

[0040] The centrifugal compressor 10 includes a thrust collar 48. The thrust collar 48 protrudes in an annular shape from the outer circumferential surface of the first shaft member 44. The thrust collar 48 is disk-shaped. The thrust collar 48 is fixed to the outer circumferential surface of the first shaft member 44 in a state in which the thrust collar 48 protrudes in an annular shape from the outer circumferential surface of the first shaft member 44 outward in the radial direction of the rotating shaft 43. Therefore, the thrust collar 48 is separate from the first shaft member 44. The thrust collar 48 is disposed in the thrust bearing accommodating chamber 19. The thrust collar 48 rotates integrally with the first shaft member 44.

[0041] The centrifugal compressor 10 includes a first impeller 49. The first impeller 49 is attached to the second end of the first shaft member 44. Therefore, the first impeller 49 is connected to the first shaft member 44. The first impeller 49 is disposed closer to the second end of the first shaft member 44 than the thrust collar 48 of the first shaft member 44. The first impeller 49 is cylindrical and gradually reduces in diameter from the back surface to the tip surface. The first impeller 49 is housed in the first impeller chamber 23. Therefore, the first impeller chamber 23 houses the first impeller 49. The outer edge of the first impeller 49 extends along the inner circumferential surface of the first impeller chamber 23. The first impeller 49 rotates integrally with the first shaft member 44 to compress air. Therefore, the first impeller 49 is an impeller that rotates integrally with the rotating shaft 43 to compress air.

[0042] The centrifugal compressor 10 includes a second impeller 50. The second impeller 50 is attached to the second end of the second shaft member 45. Therefore, the second impeller 50 is connected to the second shaft member 45. The second impeller 50 is cylindrical and gradually reduces in diameter from the back surface to the tip surface. The second impeller 50 is housed in the second impeller chamber 28. Therefore, the second impeller chamber 28 houses the second impeller 50. The outer edge of the second impeller 50 extends along the inner circumferential surface of the second impeller chamber 28. The second impeller 50 rotates integrally with the second shaft member 45 to compress the air compressed with the rotation of the first impeller 49. Therefore, the second impeller 50 is an impeller that rotates integrally with the rotating shaft 43 to compress the air.

[0043] The rotating shaft 43, the first impeller 49, and the second impeller 50 constitute a rotating body 60. Thus, the centrifugal compressor 10 is equipped with the rotating body 60. The rotating body 60 includes the rotating shaft 43, the first impeller 49, and the second impeller 50. The rotor 33 rotates integrally with the first shaft member 44 and the second shaft member 45. Thus, the rotor 33 rotates integrally with the rotating shaft 43. The rotor 33 constitutes a part of the rotating body 60. The motor 31 rotates the rotating shaft 43.

[0044] The centrifugal compressor 10 includes a first radial bearing 51 and a second radial bearing 52. The first radial bearing 51 is cylindrical. The first radial bearing 51 is held by the first radial bearing holder 21. Therefore, the first radial bearing holder 21 holds the first radial bearing 51. The second radial bearing 52 is cylindrical. The second radial bearing 52 is held by the second radial bearing holder 26. Therefore, the second radial bearing holder 26 holds the second radial bearing 52.

[0045] The first radial bearing 51 supports the first shaft member 44 rotatably in the radial direction. The second radial bearing 52 supports the second shaft member 45 rotatably in the radial direction. The first radial bearing 51 and the second radial bearing 52 support the rotor 33 rotatably in the radial direction at both sides of the cylindrical member 41 in the axial direction of the cylindrical member 41. The "radial direction" is a direction perpendicular to the axial direction of the cylindrical member 41.

[0046] The centrifugal compressor 10 includes a thrust bearing 53. The thrust bearing 53 is accommodated in the thrust bearing accommodation chamber 19. Thus, the thrust bearing accommodation chamber 19 accommodates the thrust bearing 53. The thrust bearing 53 rotatably supports the thrust collar 48 in the thrust direction. Thus, the thrust bearing 53 rotatably supports the rotating shaft 43 in the thrust direction between the first impeller 49 and the first radial bearing 51 via the thrust collar 48. Note that the "thrust direction" is a direction parallel to the axial direction of the rotating shaft 43. In this manner, the rotating shaft 43 is rotatably supported by the housing 11.

[0047] The centrifugal compressor 10 includes a connecting pipe 61. A first end of the connecting pipe 61 is connected to the first discharge chamber 24. A second end of the connecting pipe 61 is connected to the second suction port 27. Air discharged to the first discharge chamber 24 flows through the connecting pipe 61. Then, the air that has passed through the connecting pipe 61 is sucked into the second impeller chamber 28 through the second suction port 27.

[0048] A supply pipe 62 is connected to the second discharge chamber 29. The supply pipe 62 is connected to a fuel cell stack 63. A first end of the supply pipe 62 is connected to the second discharge chamber 29. A second end of the supply pipe 62 is connected to the fuel cell stack 63.

[0049] The air drawn into the first impeller chamber 23 through the first intake port 22 is accelerated by the rotation of the first impeller 49 and sent into the first diffuser passage 25, where it is pressurized by passing through the first diffuser passage 25. The air that has passed through the first diffuser passage 25 is then discharged into the first discharge chamber 24. The air that has been discharged into the first discharge chamber 24 is drawn into the second impeller chamber 28 through the connection pipe 61 and the second intake port 27. The air drawn into the second impeller chamber 28 is accelerated by the rotation of the second impeller 50 and sent into the second diffuser passage 30, where it is pressurized by passing through the second diffuser passage 30. The air that has passed through the second diffuser passage 30 is then discharged into the second discharge chamber 29. The air that has been discharged into the second discharge chamber 29 is supplied to the fuel cell stack 63 through the supply pipe 62. Thus, the centrifugal compressor 10 supplies air to the fuel cell stack 63. The oxygen contained in the air supplied to the fuel cell stack 63 contributes to power generation in the fuel cell stack 63. The air exhausted from the fuel cell stack 63 is released into the atmosphere as exhaust gas.

[0050] The motor housing 12 has an introduction passage 64. Therefore, the housing 11 has the introduction passage 64. The introduction passage 64 is formed at an end of the peripheral wall 12b of the motor housing 12 located on the first plate 15 side. A first end of the introduction passage 64 opens to the outer circumferential surface of the peripheral wall 12b of the motor housing 12. A second end of the introduction passage 64 opens to the inner circumferential surface of the peripheral wall 12b of the motor housing 12. The second end of the introduction passage 64 communicates with a portion between the resin 37 and the first plate 15 in the motor chamber 18.

[0051] The centrifugal compressor 10 includes a branch pipe 65. The branch pipe 65 branches off from the middle of the connection pipe 61. A first end of the branch pipe 65 is connected to the connection pipe 61. A second end of the branch pipe 65 is connected to a first end of the introduction passage 64. An intercooler 66 is provided in the middle of the branch pipe 65. The intercooler 66 cools the air flowing through the branch pipe 65.

[0052] The motor housing 12 has a discharge passage 67. Therefore, the housing 11 has the discharge passage 67. The discharge passage 67 penetrates the second radial bearing retaining portion 26 and the end wall 12a of the motor housing 12. A first end of the discharge passage 67 communicates with the inside of the motor chamber 18. A second end of the discharge passage 67 communicates with the outside of the housing 11.

[0053] A portion of the air flowing through the connection pipe 61 flows into the branch pipe 65. The air flowing through the branch pipe 65 is cooled by the intercooler 66. Then, the air cooled by the intercooler 66 is introduced into the motor chamber 18 via the introduction passage 64. Therefore, the introduction passage 64 introduces a portion of the air compressed by the rotation of the first impeller 49 into the motor chamber 18.

[0054] The air introduced into the motor chamber 18 passes through the gap G1 between the stator 32 and the rotor 33. Then, the air that has passed through the gap G1 is discharged to the outside of the housing 11 via the discharge passage 67. Therefore, the discharge passage 67 discharges the air that has been introduced into the motor chamber 18 from the introduction passage 64 and passed through the gap G1 between the stator 32 and the rotor 33 to the outside of the housing 11. In the centrifugal compressor 10, the permanent magnets 42 are cooled by the air that passes through the gap G1.

[0055] <End face covering part> 3, the first resin portion 38 has an end surface covering portion 70 that covers an end surface of the stator core 34 located on the first plate 15 side and that is located radially inward of the rotating shaft 43 from the first coil end 36a. Thus, the resin 37 has an end surface covering portion 70 that covers a portion of the stator core 34 located radially inward of the rotating shaft 43 from the coil end 36. The end surface covering portion 70 faces the first radial bearing retaining portion 21 in the axial direction of the rotating shaft 43.

[0056] <Opposite part> The tip surface of the first radial bearing retaining portion 21 is located radially inward of the rotating shaft 43 relative to the first coil end 36a. The tip surface of the first radial bearing retaining portion 21 is an end surface located on the first plate 15 side of the stator core 34, and faces a portion located radially inward of the rotating shaft 43 relative to the first coil end 36a in the axial direction of the rotating shaft 43 via an end surface covering portion 70. Thus, the tip surface of the first radial bearing retaining portion 21 is an opposing portion 71 that faces a portion of the end surface of the stator core 34 located radially inward of the rotating shaft 43 relative to the coil end 36 in the axial direction of the rotating shaft 43. Thus, the housing 11 has the opposing portion 71.

[0057] <Nozzle> 3 and 4, the centrifugal compressor 10 includes a plurality of nozzle vanes 72. The plurality of nozzle vanes 72 protrude from the end face covering portion 70 toward the opposing portion 71 of the first radial bearing holder 21. The plurality of nozzle vanes 72 are integrally formed with the resin 37.

[0058] As shown in Fig. 4, the nozzle vanes 72 are arranged in a line in the circumferential direction around the axis L1 of the rotary shaft 43. The nozzle vanes 72 are arranged at equal intervals in the circumferential direction around the axis L1 of the rotary shaft 43. The nozzle vanes 72 are thin-plate shaped and curved so that a downstream edge 72a located on the downstream side in the air flow direction is closer to the gap G1 than an upstream edge 72b located on the upstream side in the air flow direction, and is located on the leading side in the rotation direction of the rotary shaft 43. Each nozzle vane 72 is formed in the resin 37 so that the downstream edge 72a of the nozzle vane 72 is located at a position away from the inner circumferential surface of the third resin portion 40.

[0059] The gap between the nozzle vanes 72 adjacent to each other in the circumferential direction of the rotary shaft 43 is gradually narrowed as it approaches the gap G1. Therefore, the cross-sectional area of ​​the air flow path formed by the gap between the nozzle vanes 72 adjacent to each other in the circumferential direction of the rotary shaft 43 is gradually reduced as it approaches the gap G1. In this manner, the nozzle 73 is formed by the gap between the nozzle vanes 72 adjacent to each other in the circumferential direction of the rotary shaft 43. Therefore, in this embodiment, the centrifugal compressor 10 includes a plurality of nozzles 73. Each nozzle 73 is a fixed nozzle. Each nozzle 73 converts the pressure energy of the air passing through each nozzle 73 into velocity energy. Each nozzle 73 is disposed at a position away from the inner circumferential surface of the third resin portion 40. Therefore, in the motor chamber 18, there is a space between each nozzle 73 and the gap G1.

[0060] The direction of air passing through each nozzle 73 is set to be the circumferential direction of the rotating shaft 43. Therefore, the direction of air introduction into gap G1 in each nozzle 73 is set to be the circumferential direction of the rotating shaft 43. In this way, the nozzle 73 generates a swirling flow of air upstream of the gap G1 in the air flow direction. The nozzle 73 is located upstream of the gap G1 in the air flow direction and radially inward of the rotating shaft 43 than the coil end 36.

[0061] <Communication path> The centrifugal compressor 10 includes a communication passage 80. The communication passage 80 allows the swirling airflow generated by the nozzles 73 to flow into the gap G1. The communication passage 80 is a space that exists between each nozzle 73 and the gap G1 in the airflow direction within the motor chamber 18. Therefore, the communication passage 80 is located downstream of each nozzle 73 in the airflow direction and upstream of the gap G1 in the airflow direction. The communication passage 80 connects each nozzle 73 to the gap G1.

[0062] [Operation of the embodiment] Next, the operation of the embodiment will be described. The swirling air flow generated by each nozzle 73 flows into the gap G1 between the stator 32 and the rotor 33 through the communication passage 80, and the swirling air flow that flows into the gap G1 between the stator 32 and the rotor 33 assists the rotation of the rotor 33. As a result, mechanical loss of the rotor 33, so-called "windage loss", is less likely to occur. Therefore, the temperature rise due to the windage loss of the air flowing through the gap G1 between the stator 32 and the rotor 33 is suppressed. Therefore, it is possible to lower the average temperature of the air flowing through the gap G1 between the stator 32 and the rotor 33 by the amount of the temperature rise due to the windage loss being suppressed. As a result, the permanent magnets 42 are efficiently cooled by the air flowing through the gap G1 between the stator 32 and the rotor 33.

[0063] [Effects of the embodiment] The embodiment can provide the following effects. (1) The centrifugal compressor 10 includes a nozzle 73 and a communication passage 80. The nozzle 73 generates a swirling flow of air upstream of the gap G1 between the stator 32 and the rotor 33 in the air flow direction. The communication passage 80 allows the swirling flow of air generated by the nozzle 73 to flow into the gap G1 between the stator 32 and the rotor 33. According to this, the swirling flow of air generated by the nozzle 73 flows into the gap G1 between the stator 32 and the rotor 33 through the communication passage 80, and the swirling flow of air that has flowed into the gap G1 between the stator 32 and the rotor 33 assists the rotation of the rotor 33. As a result, mechanical loss of the rotor 33, so-called "windage loss", is less likely to occur. Therefore, the temperature rise due to windage loss of the air flowing through the gap G1 between the stator 32 and the rotor 33 can be suppressed. Therefore, it is possible to lower the average temperature of the air flowing through the gap G1 between the stator 32 and the rotor 33 by the amount of the temperature rise due to windage loss being suppressed. As a result, the permanent magnets 42 can be efficiently cooled by the air flowing through the gap G1 between the stator 32 and the rotor 33.

[0064] (2) The nozzle 73 is located upstream of the gap G1 in the air flow direction and radially inward of the rotating shaft 43 than the coil end 36. This allows the nozzle 73 to generate a swirling air flow just before the air flows into the gap G1 between the stator 32 and the rotor 33. This makes it possible to cause the swirling air flow to flow into the gap G1 between the stator 32 and the rotor 33 while suppressing pressure loss of the swirling air flow. As a result, it is possible to further easily suppress a temperature rise of the air flowing through the gap G1 between the stator 32 and the rotor 33, and therefore the permanent magnets 42 can be more efficiently cooled by the air flowing through the gap G1 between the stator 32 and the rotor 33.

[0065] (3) The centrifugal compressor 10 includes a plurality of nozzle vanes 72 that protrude from the end surface covering portion 70 and are arranged in a line in the circumferential direction around the axis line L1 of the rotary shaft 43. The nozzle vanes 72 are thin-plate shaped and curved such that a downstream edge 72a located downstream in the air flow direction is closer to the gap G1 than an upstream edge 72b located upstream in the air flow direction and is located on the leading side in the rotation direction of the rotary shaft 43. A nozzle 73 is formed by a gap between the nozzle vanes 72 adjacent to each other in the circumferential direction of the rotary shaft 43. This configuration is suitable for forming a nozzle 73 located upstream of the gap G1 in the air flow direction and radially inward of the rotary shaft 43 than the coil end 36.

[0066] (4) Since the nozzle 73 is formed by the multiple nozzle vanes 72, it is not necessary to set the direction of air introduction into the motor chamber 18 in the introduction passage 64 to the circumferential direction of the rotating shaft 43 in order to generate a swirling air flow. Therefore, it is possible to generate a swirling air flow upstream of the gap G1 in the air flow direction while facilitating the design of the housing 11.

[0067] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0068] As shown in FIG. 5, the centrifugal compressor 10 may be configured to include a plurality of nozzle vanes 72 that protrude from the opposing portion 71 and are arranged side by side in the circumferential direction around the axis L1 of the rotary shaft 43. The nozzle vanes 72 are thin-plate shaped and curved such that a downstream edge 72a located downstream in the air flow direction is closer to the gap G1 than an upstream edge 72b located upstream in the air flow direction and is located on the leading side in the rotation direction of the rotary shaft 43. The plurality of nozzle vanes 72 are integrally formed with the first plate 15. A nozzle 73 is formed by a gap between the nozzle vanes 72 adjacent to each other in the circumferential direction of the rotary shaft 43. This configuration is suitable for forming the nozzle 73 that is located upstream of the gap G1 in the air flow direction and radially inward of the rotary shaft 43 than the coil end 36. In this case, the centrifugal compressor 10 may not be configured to include a plurality of nozzle vanes 72 that protrude from the end face covering portion 70 and are arranged side by side in the circumferential direction around the axis L1 of the rotary shaft 43.

[0069] 6 and 7, the downstream end of the introduction passage 64 located on the motor chamber 18 side may constitute a nozzle 74. The nozzle 74 is formed smaller than the flow path cross-sectional area located upstream of the downstream end of the introduction passage 64 in the air flow direction. In this manner, the downstream end of the introduction passage 64 located on the motor chamber 18 side constitutes the nozzle 74 by being smaller than the flow path cross-sectional area located upstream of the downstream end in the air flow direction. The direction in which the nozzle 74 introduces air into the motor chamber 18 is set to be the circumferential direction of the rotation shaft 43.

[0070] As shown in FIG. 7, the direction of introduction of air from the nozzle 74 into the motor chamber 18 is a tangential direction to the inner peripheral surface of the peripheral wall 12b of the motor housing 12. The centrifugal compressor 10 has a scroll wall 75. The scroll wall 75 protrudes from the end face of the first plate 15 located on the motor housing 12 side. The scroll wall 75 is integrally formed with the first plate 15. The scroll wall 75 extends around the axis L1 of the rotating shaft 43 around the first radial bearing retaining portion 21. The inner surface of the scroll wall 75 guides the air introduced from the nozzle 74 in the circumferential direction of the rotating shaft 43 and gradually approaches the axis L1 of the rotating shaft 43. In this way, a swirling flow of the air introduced from the introduction passage 64 into the motor chamber 18 is generated.

[0071] In the motor chamber 18, the space inside the scroll wall 75, the space inside the first resin portion 38, and the space between the end face covering portion 70 and the opposing portion 71 form a communication passage 81 that allows the swirling air flow generated by the nozzle 74 to flow into the gap G1. The communication passage 81 is a space that exists between the nozzle 74 and the gap G1 in the air flow direction in the motor chamber 18. Therefore, the communication passage 81 is located downstream of the nozzle 74 in the air flow direction and upstream of the gap G1 in the air flow direction. The communication passage 81 connects the nozzle 74 and the gap G1.

[0072] According to this, air is introduced into the motor chamber 18 from the introduction passage 64 in a state where a swirling flow of air is generated by the nozzle 74. Then, the swirling flow of air introduced into the motor chamber 18 from the introduction passage 64 can be made to flow into the gap G1 between the stator 32 and the rotor 33 via the communication passage 81.

[0073] 6 and 7 , the direction in which the nozzle 74 introduces air into the motor chamber 18 does not have to be a tangential direction to the inner circumferential surface of the peripheral wall 12b of the motor housing 12. The point is that it is only necessary that the nozzle 74 introduces air into the motor chamber 18 in the circumferential direction of the rotation shaft 43.

[0074] In the embodiment, for example, the nozzle 73 and the gap G1 may be directly connected to each other. In this case, the communication passage 80 corresponds to the boundary between the nozzle 73 and the gap G1. In the above embodiment, the intercooler 66 does not necessarily have to be provided in the branch pipe 65 .

[0075] In the above embodiment, the introduction passage 64 may introduce part of the air compressed in accordance with the rotation of the second impeller 50 into the motor chamber 18. In the above embodiment, the centrifugal compressor 10 does not have to include the second impeller 50.

[0076] In the above-mentioned embodiment, the centrifugal compressor 10 may be configured to include a turbine wheel instead of the second impeller 50. In the above-mentioned embodiments, the magnetic body is not limited to the permanent magnet 42 and may be, for example, a laminated core, an amorphous core, or a powder core.

[0077] In the embodiment, the cylindrical member 41 may be made of, for example, carbon fiber reinforced plastic. In short, the material of the cylindrical member 41 is not particularly limited. In the above embodiment, the rotor 33 may include a cylindrical rotor core formed by laminating a plurality of electromagnetic steel sheets, and a magnetic body embedded in the rotor core. In this configuration, the rotating shaft 43 passes through the inside of the rotor core.

[0078] In the above-mentioned embodiment, the centrifugal compressor 10 does not have to be mounted on a fuel cell vehicle. In other words, the centrifugal compressor 10 is not limited to being mounted on a vehicle. In the above-mentioned embodiment, the centrifugal compressor 10 is not limited to be used for compressing the air supplied to the fuel cell stack 63. In short, the centrifugal compressor 10 may be used for compressing a fluid. [Explanation of symbols]

[0079] 10...centrifugal compressor, 11...housing, 18...motor chamber, 31...motor, 32...stator, 33...rotor, 34...stator core, 35...coil, 36...coil end, 37...resin, 42...permanent magnet which is a magnetic body, 43...rotating shaft, 49...first impeller which is an impeller, 50...second impeller which is an impeller, 60...rotating body, 64...inlet passage, 67...discharge passage, 70...end surface covering portion, 71...opposing portion, 72...nozzle vane, 72a...downstream edge, 72b...upstream edge, 73, 74...nozzle, 80, 81...connecting passage, G1...gap.

Claims

1. a rotor including a rotating shaft and an impeller that rotates integrally with the rotating shaft to compress a fluid; A motor that rotates the rotary shaft; a housing having a motor chamber for accommodating the motor; The motor is a cylindrical stator fixed to the housing; a rotor that rotates integrally with the rotating shaft, is disposed inside the stator, and constitutes a part of the rotating body; The rotor has a magnetic body, The housing includes: an introduction passage for introducing a portion of the fluid compressed as the impeller rotates into the motor chamber; a discharge passage for discharging, to the outside of the housing, the fluid that has been introduced from the introduction passage into the motor chamber and passed through a gap between the stator and the rotor, A centrifugal compressor in which the magnetic body is cooled by a fluid passing through the gap, a nozzle that generates a swirling flow of the fluid upstream of the gap in a flow direction of the fluid; a communication passage through which the swirling flow of the fluid generated by the nozzle flows into the gap.

2. The stator includes: A stator core; a coil end that is a part of a coil wound around the stator core and protrudes from an end surface of the stator core, 2. The centrifugal compressor according to claim 1, wherein the nozzle is located upstream of the gap in the fluid flow direction and radially inward of the coil end in the rotating shaft.

3. the stator includes a resin that molds the stator core, the resin has an end surface covering portion that covers a portion of the end surface of the stator core that is located radially inward of the coil end with respect to the rotating shaft, a plurality of nozzle vanes protruding from the end surface covering portion and arranged in a circumferential direction around an axis of the rotary shaft; the nozzle vane has a thin plate shape that is curved such that a downstream edge located on a downstream side in a flow direction of the fluid is closer to the gap than an upstream edge located on an upstream side in the flow direction of the fluid and is located on a leading side in a rotation direction of the rotary shaft, 3. The centrifugal compressor according to claim 2, wherein the nozzle is formed by a gap between adjacent nozzle vanes in the circumferential direction of the rotary shaft.

4. the housing has a portion of the end surface of the stator core that is located radially inward of the coil end of the rotating shaft and a facing portion that faces the axial direction of the rotating shaft, a plurality of nozzle vanes protruding from the opposing portion and arranged side by side in a circumferential direction around an axis of the rotary shaft; the nozzle vane has a thin plate shape that is curved such that a downstream edge located on a downstream side in a flow direction of the fluid is closer to the gap than an upstream edge located on an upstream side in the flow direction of the fluid and is located on a leading side in a rotation direction of the rotary shaft, 3. The centrifugal compressor according to claim 2, wherein the nozzle is formed by a gap between adjacent nozzle vanes in the circumferential direction of the rotary shaft.

5. a downstream end portion of the introduction passage located on the motor chamber side is formed to be smaller than a flow passage cross-sectional area located upstream of the downstream end portion in a flow direction of the fluid, thereby forming the nozzle, 2. The centrifugal compressor according to claim 1, wherein the nozzle introduces the fluid into the motor chamber in a circumferential direction of the rotating shaft.

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