Centrifugal compressor

Abstract

To provide a centrifugal compressor which can achieve improvement of productivity while inhibiting increase in size.SOLUTION: A connection passage 70 is formed by a first impeller housing 10b, a motor housing 10a, and a second impeller housing 10c. This prevents, for example, formation of a gap between a housing 10 and a pipe in a centrifugal compressor 100 unlike in a configuration in which a first discharge port 39 and a second suction port 40 are connected to each other by attaching the pipe formed separately from the housing 10 to the housing 10. The connection passage 70 is formed only by sequentially stacking the first impeller housing 10b, the motor housing 10a, and the second impeller housing 10c in an axial direction of a rotary shaft 50. This eliminates, for example, a need to provide a structure in the pipe that absorbs dimensional tolerances that occur between the housing 10 and the pipe when the pipe is attached to the housing 10.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A centrifugal compressor includes a rotating shaft, a motor, and a housing. The motor rotates the rotating shaft. Further, the centrifugal compressor may include a first impeller and a second impeller. The first impeller rotates integrally with the rotating shaft to compress a fluid. The second impeller may be provided on the side opposite to the first impeller with the motor interposed therebetween with respect to the rotating shaft.

[0003] The housing has a first impeller chamber, a second impeller chamber, a first suction port, a first discharge port, a second suction port, and a second discharge port. The first impeller chamber houses the first impeller. The second impeller chamber houses the second impeller. The first suction port sucks a fluid into the first impeller chamber. The first discharge port discharges the fluid compressed by the rotation of the first impeller. The second suction port sucks a fluid into the second impeller chamber. The centrifugal compressor includes a connecting passage. The second discharge port discharges the fluid compressed by the rotation of the second impeller. The connecting passage connects the first discharge port and the second suction port so that the fluid flows from the first discharge port toward the second suction port. The connecting passage is formed by a pipe, which is a separate member from the housing, as in Patent Document 1 for example. Then, by attaching the pipe to the housing, the first discharge port and the second suction port are connected by the connecting passage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a configuration where a pipe, which is a member separate from the housing, is attached to the housing to connect the first discharge port and the second suction port by a connection path, in a centrifugal compressor, a gap is formed between the housing and the pipe. This gap formed between the housing and the pipe is a dead space in the centrifugal compressor. Therefore, the centrifugal compressor is unnecessarily enlarged by the amount of the gap formed between the housing and the pipe.

[0006] In addition, a dimensional tolerance occurs between the housing and the pipe. For this reason, a structure that can absorb the dimensional tolerance that occurs between the housing and the pipe when the pipe is attached to the housing, for example, a device such as being provided on the pipe is required, which is a factor that reduces the productivity of the centrifugal compressor. Therefore, it is desired to improve productivity while suppressing the enlargement of the centrifugal compressor.

Means for Solving the Problems

[0007] A centrifugal compressor for solving the above problems includes a rotating shaft, a motor for rotating the rotating shaft, a first impeller that rotates integrally with the rotating shaft to compress a fluid, a second impeller that is provided on the opposite side of the first impeller with the motor interposed therebetween with respect to the rotating shaft and rotates integrally with the rotating shaft, a first impeller housing that defines a first impeller chamber for housing the first impeller, has a first suction port for sucking a fluid into the first impeller chamber, and a first discharge port for discharging the fluid compressed by the rotation of the first impeller, a motor housing that defines a motor chamber for housing the motor, and a second impeller housing that defines a second impeller chamber for housing the second impeller, has a second suction port for sucking a fluid into the second impeller chamber, and a second discharge port for discharging the fluid compressed by the rotation of the second impeller, and a housing having the second impeller housing, and a connection path that connects the first discharge port and the second suction port so that the fluid flows from the first discharge port toward the second suction port. The connection path includes a first impeller housing connection path provided in the first impeller housing and connected to the first discharge port, a second impeller housing connection path provided in the second impeller housing and connected to the second suction port, and a motor housing connection path formed through the motor housing and connecting the first impeller housing connection path and the second impeller housing connection path. The gist is that the first impeller housing, the motor housing, and the second impeller housing are sequentially stacked in the axial direction of the rotating shaft.

[0008] According to this, the connection path is composed of a first impeller housing, a motor housing, and a second impeller housing that the housing has. That is, the connection path is formed inside the housing. Therefore, for example, in a centrifugal compressor, a structure in which a first discharge port and a second suction port are connected by a connection path by attaching a pipe, which is a separate member from the housing, to the housing does not form a gap between the housing and the pipe. Thus, the centrifugal compressor does not needlessly increase in size by the amount of the gap formed between the housing and the pipe. As a result, an increase in the size of the centrifugal compressor can be suppressed. Further, the connection path can be configured simply by sequentially laminating the first impeller housing, the motor housing, and the second impeller housing in the axial direction of the rotation axis. Therefore, a structure that can absorb dimensional tolerances generated between the housing and the pipe when attaching the pipe to the housing, for example, does not require a device such as providing it in the pipe. For this reason, the productivity of the centrifugal compressor can be improved. From the above, while suppressing an increase in the size of the centrifugal compressor, the productivity can be improved.

[0009] In the centrifugal compressor, the motor housing may include a cooling medium passage through which a cooling medium for cooling the motor flows, and the cooling medium passage may be provided between the motor and the motor housing connection path in the radial direction of the rotation axis.

[0010] According to this, in addition to the motor, the fluid flowing through the motor housing connection path can also be cooled by the cooling medium flowing through the cooling medium passage. Therefore, the fluid cooled by the cooling medium can be sucked into the second impeller chamber through the motor housing connection path, the second impeller housing connection path, and the second suction port. As a result, the compression efficiency of the fluid accompanying the rotation of the second impeller can be improved.

[0011] In the centrifugal compressor described above, the motor has a cylindrical stator and a rotor provided on the rotating shaft and rotating integrally with the rotating shaft. The motor housing has a first motor housing with the stator fixed to its inner peripheral surface and a second motor housing through which the motor housing connection path is formed. The cooling medium path may be defined such that the cooling medium flows between the first motor housing and the second motor housing.

[0012] For example, when the cooling medium path is constituted by a single housing member, in order to manufacture such a housing member, it is necessary to manufacture it by a casting method using a core. The manufacturing method using a core incurs higher manufacturing costs compared to the manufacturing method without using a core. Therefore, the cooling medium path is defined such that the cooling medium flows between the first motor housing and the second motor housing. Each of the first motor housing and the second motor housing that defines the cooling medium path does not need to be manufactured by a casting method using a core. That is, in the motor housing having the first motor housing and the second motor housing, it is possible to form the cooling medium path by a manufacturing method without using a core. As a result, the above configuration can form a cooling medium path in the motor housing while suppressing the manufacturing cost.

[0013] In the centrifugal compressor described above, the second impeller housing may have a third suction port that sucks fluid in the axial direction facing the motor housing connection path, and a guide portion that guides the fluid sucked in the axial direction from the third suction port in the radial direction of the rotating shaft so as to approach the second suction port, and further guides the fluid flowing in the radial direction in the axial direction toward the second suction port.

[0014] According to this, the third suction port sucks the fluid flowing through the motor housing connection path in the axial direction of the rotating shaft. The guide portion guides the fluid sucked in the axial direction of the rotating shaft from the third suction port in the radial direction of the rotating shaft so as to approach the second suction port. Further, the guide portion further guides the fluid flowing in the radial direction of the rotating shaft in the axial direction of the rotating shaft toward the second suction port. As a result, the guiding of the fluid by the guide portion can suppress the formation of vortices when the fluid changes its flow direction. Therefore, since the second impeller housing has the guide portion, the pressure loss of the fluid flowing from the third suction port toward the second suction port can be reduced, and thus the compression efficiency of the fluid accompanying the rotation of the second impeller can be improved.

[0015] In the centrifugal compressor, the second impeller housing may include a second impeller housing base portion in which the third suction port, the second suction port, and the second discharge port are open, and a third discharge port that is open so as to discharge the fluid sucked from the third suction port toward the guide portion; and a second impeller housing lid portion in which a groove-shaped guide portion that connects the third discharge port and the second suction port and allows the fluid to flow from the third discharge port toward the second suction port is formed.

[0016] For example, when forming a flow path through which the fluid flows from the third suction port to the second suction port with one housing member, in order to manufacture the housing member, it may be necessary to use a casting method using a mold, which may increase the manufacturing cost. Therefore, the second impeller housing has a second impeller housing base portion and a second impeller housing lid portion. According to this, it is not necessary to use a casting method using a mold as in the case of forming a flow path through which the fluid flows from the third suction port to the second suction port with one housing member, so that an increase in manufacturing cost can be avoided.

Advantages of the Invention

[0017] According to the present invention, it is possible to improve productivity while suppressing an increase in the size of the centrifugal compressor.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0019] Hereinafter, an embodiment in which a centrifugal compressor is embodied will be described with reference to FIGS. 1 to 5. The centrifugal compressor of this embodiment is mounted on a fuel cell vehicle. The centrifugal compressor compresses air as a fluid.

[0020] <Basic Structure of Centrifugal Compressor> As shown in FIG. 1, the centrifugal compressor 100 includes a housing 10. The housing 10 is made of a metal material. The housing 10 is made of, for example, aluminum. The housing 10 has a motor housing 10a, a first impeller housing 10b, and a second impeller housing 10c. The motor housing 10a has a first motor housing 14 and a connection path forming housing 13. The first impeller housing 10b has a first compressor housing 11 and a second plate 17. The second impeller housing 10c has a second compressor housing 12 and a third plate 18. The second compressor housing 12 is composed of a second impeller housing base 12a and a second impeller housing lid 19. That is, the second impeller housing 10c has a second impeller housing base 12a and a second impeller housing lid 19.

[0021] The first motor housing 14 has an end wall 14a and a peripheral wall 14b. The first motor housing 14 is cylindrical. The end wall 14a is plate-shaped. The peripheral wall 14b extends cylindrically from the outer peripheral portion of the end wall 14a. The first motor housing 14 is manufactured by die casting.

[0022] The connection path forming housing 13 is formed by the second motor housing 15 and the first plate 16. That is, the motor housing 10a has the first motor housing 14 and the second motor housing 15. The second motor housing 15 and the first plate 16 are manufactured by die casting.

[0023] The second motor housing 15 is cylindrical. The second motor housing 15 has a motor housing accommodation hole 15c. The second motor housing 15 has an accommodation hole defining surface 15a. The accommodation hole defining surface 15a defines the motor housing accommodation hole 15c. The motor housing accommodation hole 15c extends in the axial direction of the second motor housing 15 and opens at both end faces in the axial direction of the second motor housing 15. The motor housing accommodation hole 15c accommodates the first motor housing 14 such that the outer peripheral surface of the peripheral wall 14b of the first motor housing 14 faces the accommodation hole defining surface 15a in the radial direction of the second motor housing 15. The axis of the second motor housing 15 coincides with the axis of the peripheral wall 14b of the first motor housing 14.

[0024] The centrifugal compressor 100 is provided with a cooling medium passage 13a. The cooling medium passage 13a is defined by the outer peripheral surface of the peripheral wall 14b of the first motor housing 14 and the housing hole defining surface 15a. The cooling medium passage 13a is defined so that cooling water flows between the first motor housing 14 and the second motor housing 15. That is, the cooling medium passage 13a is defined by the first motor housing 14 and the second motor housing 15. The cooling medium passage 13a extends along the peripheral wall 14b of the first motor housing 14 and is annular, surrounding the peripheral wall 14b. The second motor housing 15 has a supply port 13e and a discharge port 13f. The supply port 13e supplies cooling water to the cooling medium passage 13a. The discharge port 13f discharges the cooling water that has flowed through the cooling medium passage 13a to the outside of the housing 10. The cooling water flowing through the cooling medium passage 13a cools the first motor housing 14 and the second motor housing 15.

[0025] A plurality of fins 14d are provided on the outer peripheral surface of the peripheral wall 14b of the first motor housing 14. The plurality of fins 14d project from the outer peripheral surface of the peripheral wall 14b of the first motor housing 14 into the cooling medium passage 13a. Each fin 14d is an annular thin plate extending along the outer peripheral surface of the peripheral wall 14b. The plurality of fins 14d are arranged at intervals in the axial direction of the first motor housing 14 on the outer peripheral surface of the peripheral wall 14b of the first motor housing 14. The plurality of fins 14d are integrally formed with the first motor housing 14. The cooling water flows inside the cooling medium passage 13a along each fin 14d in the circumferential direction of the first motor housing 14 and the second motor housing 15.

[0026] The first plate 16 is connected to the end of the peripheral wall 14b of the first motor housing 14 on the side opposite to the end wall 14a, and to the first end of the second motor housing 15. The first plate 16 is connected to the peripheral wall 14b of the first motor housing 14 and the second motor housing 15 in a state where the thickness direction of the first plate 16 coincides with the axial direction of the peripheral wall 14b of the first motor housing 14 and the axial direction of the second motor housing 15. The first plate 16 closes the opening of the peripheral wall 14b of the first motor housing 14. And the motor chamber 14c is partitioned by the first motor housing 14 and the first plate 16. Therefore, the motor housing 10a defines the motor chamber 14c.

[0027] The first plate 16 has a first bearing holding portion 21. The first bearing holding portion 21 is cylindrical. The first bearing holding portion 21 protrudes into the motor chamber 14c. The axis of the first bearing holding portion 21 coincides with the axis of the peripheral wall 14b of the first motor housing 14.

[0028] The end wall 14a of the first motor housing 14 has a second bearing holding portion 25. The second bearing holding portion 25 is cylindrical. The second bearing holding portion 25 protrudes into the motor chamber 14c. The axis of the second bearing holding portion 25 coincides with the axis of the first bearing holding portion 21.

[0029] The second plate 17 is manufactured by die casting. The second plate 17 is connected to the end face of the first plate 16 on the side opposite to the first motor housing 14 and the second motor housing 15. The second plate 17 is connected to the first plate 16 in a state where the thickness direction of the second plate 17 coincides with the thickness direction of the first plate 16. The second plate 17 has a first insertion hole 23. The axis of the first insertion hole 23 coincides with the axis of the first bearing holding portion 21. The first insertion hole 23 communicates with the inside of the first bearing holding portion 21.

[0030] The third plate 18 is manufactured by die casting. The third plate 18 is connected to the outer surface of the end wall 14a of the first motor housing 14 and the second end of the second motor housing 15. The third plate 18 is connected to the end wall 14a of the first motor housing 14 and the second motor housing 15 in a state where the thickness direction of the third plate 18 coincides with the thickness direction of the end wall 14a of the first motor housing 14.

[0031] A second insertion hole 26 is formed in the third plate 18. The second insertion hole 26 penetrates the third plate 18 in the thickness direction of the third plate 18. The second insertion hole 26 communicates with the inside of the second bearing holder 25. The axis of the second insertion hole 26 coincides with the axis of the second bearing holder 25.

[0032] The centrifugal compressor 100 includes a motor 20. The motor 20 is housed in the motor chamber 14c. Therefore, the motor chamber 14c houses the motor 20. The first motor housing 14 surrounds the motor 20. The heat generated from the motor 20 is dissipated to the first motor housing 14. Since the first motor housing 14 is cooled by the cooling water flowing through the cooling medium passage 13a, the heat generated from the motor 20 is efficiently dissipated to the first motor housing 14. Thereby, the motor 20 is cooled. That is, the motor housing 10a includes a cooling medium passage 13a through which the cooling water as a cooling medium for cooling the motor 20 flows.

[0033] The first compressor housing 11 is manufactured by die casting. The first compressor housing 11 has a circular hole-shaped first suction port 35 into which air is inhaled. Accordingly, the first impeller housing 10b has the first suction port 35. The first compressor housing 11 is connected to the end face of the second plate 17 on the side opposite to the first plate 16 in a state where the axis of the first suction port 35 coincides with the axis of the first insertion hole 23. The first suction port 35 opens at the end face of the first compressor housing 11 on the side opposite to the second plate 17. Cleaned air flows into the first suction port 35 by an air cleaner (not shown).

[0034] The centrifugal compressor 100 includes a first impeller chamber 36, a first discharge chamber 37, and a first diffuser flow path 38. The first impeller chamber 36, the first discharge chamber 37, and the first diffuser flow path 38 are formed between the first compressor housing 11 and the second plate 17. Accordingly, the first impeller housing 10b defines the first impeller chamber 36. The first impeller chamber 36 communicates with the first suction port 35. The first suction port 35 sucks air into the first impeller chamber 36. The first discharge chamber 37 extends around the first impeller chamber 36 around the axis of the first suction port. The first diffuser flow path 38 communicates the first impeller chamber 36 and the first discharge chamber 37. The first impeller chamber 36 communicates with the first insertion hole 23.

[0035] As shown in FIG. 2, a first discharge port 39 is formed in the first compressor housing 11. Accordingly, the first impeller housing 10b has the first discharge port 39. The first end of the first discharge port 39 communicates with the first discharge chamber 37.

[0036] As shown in FIG. 1, the second impeller housing base 12a is manufactured by die casting. The second impeller housing base 12a has a circular hole-shaped second suction port 40. The second suction port 40 is open in the second impeller housing base 12a. Therefore, the second impeller housing 10c has the second suction port 40. The second impeller housing base 12a is connected to the end face of the third plate 18 on the side opposite to the first motor housing 14 and the second motor housing 15 with the axis of the second suction port 40 being aligned with the axis of the second insertion hole 26.

[0037] The centrifugal compressor 100 includes a second impeller chamber 41, a second discharge chamber 42, and a second diffuser flow path 43. The second impeller chamber 41, the second discharge chamber 42, and the second diffuser flow path 43 are formed between the second impeller housing base 12a and the third plate 18. Therefore, the second impeller housing 10c defines the second impeller chamber 41. The second impeller chamber 41 communicates with the second suction port 40. The second suction port 40 sucks air into the second impeller chamber 41. The second discharge chamber 42 extends around the second impeller chamber 41 around the axis of the second suction port. The second diffuser flow path 43 communicates the second impeller chamber 41 and the second discharge chamber 42. The second impeller chamber 41 communicates with the second insertion hole 26.

[0038] A second discharge port 44 is formed in the second impeller housing base 12a. The second discharge port 44 is open in the second impeller housing base 12a. In other words, the second impeller housing 10c has the second discharge port 44. The first end of the second discharge port 44 communicates with the second discharge chamber 42. The second end of the second discharge port 44 opens to the outer peripheral surface of the second impeller housing base 12a.

[0039] A supply pipe 45 is connected to the second discharge port 44. The supply pipe 45 is connected to the fuel cell stack 46. The first end of the supply pipe 45 is connected to the second discharge port 44. The second end of the supply pipe 45 is connected to the fuel cell stack 46.

[0040] The centrifugal compressor 100 includes a rotating shaft 50. The rotating shaft 50 traverses the motor chamber 14c in a state where the axis of the rotating shaft 50 coincides with the axis of the peripheral wall 14b of the first motor housing 14. The first end, which is one axial end of the rotating shaft 50, protrudes into the first impeller chamber 36 from inside the motor chamber 14c, passing through the inside of the first bearing holder 21 and the first insertion hole 23. The second end, which is the other axial end of the rotating shaft 50, protrudes into the second impeller chamber 41 from inside the motor chamber 14c, passing through the inside of the second bearing holder 25 and the second insertion hole 26.

[0041] The motor 20 includes a cylindrical stator 52 and a rotor 51. The rotor 51 is fixed to the rotating shaft 50. The rotor 51 has a cylindrical rotor core 53 fixed to the rotating shaft 50 and a plurality of permanent magnets (not shown) provided on the rotor core 53. The rotor 51 is provided on the rotating shaft 50 and rotates integrally with the rotating shaft 50.

[0042] The stator 52 is fixed to the first motor housing 14. The stator 52 is disposed outside the rotor 51. The stator 52 has a cylindrical stator core 54 and a coil 55. The stator core 54 is fixed to the inner peripheral surface of the peripheral wall 14b of the first motor housing 14. That is, the motor housing 10a has the first motor housing 14 with the stator 52 fixed to its inner peripheral surface. The coil 55 is wound around the stator core 54. When an electric current flows from a battery (not shown) to the coil 55, the rotating shaft 50 rotates integrally with the rotor 51. Therefore, the motor 20 rotates the rotating shaft 50.

[0043] The centrifugal compressor 100 includes a first hydrodynamic bearing 56 and a second hydrodynamic bearing 57. The first hydrodynamic bearing 56 is cylindrical. The first hydrodynamic bearing 56 is held by the first bearing holder 21. The first hydrodynamic bearing 56 rotatably supports the rotating shaft 50 with respect to the first plate 16.

[0044] The second hydrodynamic bearing 57 is cylindrical. The second hydrodynamic bearing 57 is held by the second bearing holder 25. The second hydrodynamic bearing 57 rotatably supports the rotating shaft 50 with respect to the end wall 14a of the first motor housing 14. Therefore, the first hydrodynamic bearing 56 and the second hydrodynamic bearing 57 are bearings that rotatably support the rotating shaft 50 with respect to the housing 10. The first hydrodynamic bearing 56 and the second hydrodynamic bearing 57 rotatably support the rotating shaft 50 with respect to the housing 10 in the radial direction.

[0045] Note that the centrifugal compressor 100 may be provided with a known thrust bearing that is a bearing for rotatably supporting the rotating shaft 50 with respect to the housing 10 in the thrust direction. The centrifugal compressor 100 includes a first impeller 61 and a second impeller 62. The first impeller 61 is connected to the first end of the rotating shaft 50. The first impeller 61 is housed in the first impeller chamber 36. Therefore, the first impeller chamber 36 houses the first impeller 61. The first impeller 61 rotates integrally with the rotating shaft 50 to compress air.

[0046] The second impeller 62 is connected to the second end of the rotating shaft 50. In other words, the second impeller 62 is provided on the side opposite to the first impeller 61 with the motor 20 interposed therebetween with respect to the rotating shaft 50. The second impeller 62 is housed in the second impeller chamber 41. Therefore, the second impeller chamber 41 houses the second impeller 62. The second impeller 62 rotates integrally with the rotating shaft 50 to compress the air after being compressed by the rotation of the first impeller 61. The first impeller 61 and the second impeller 62 rotate to compress the air supplied to the fuel cell stack 46.

[0047] The first impeller 61 and the second impeller 62 rotate integrally with the rotating shaft 50 by the drive of the motor 20. Therefore, the motor 20 rotates the first impeller 61 and the second impeller 62.

[0048] <Inverter> The centrifugal compressor 100 is provided with an inverter 65. The inverter 65 is electrically connected to the motor 20. The inverter 65 controls the driving of the motor 20 by controlling the power supplied to the coil 55.

[0049] The centrifugal compressor 100 is provided with an inverter housing 66. The inverter housing 66 houses the inverter 65. The inverter housing 66 is provided on the outer surface of the second motor housing 15. In other words, the inverter 65 is provided on the housing outer surface 10e which is the outer surface of the housing 10. The heat generated from the inverter 65 is radiated to the second motor housing 15 through the inverter housing 66. Since the second motor housing 15 is cooled by the cooling water flowing through the cooling medium passage 13a, the heat generated from the inverter 65 is efficiently radiated to the second motor housing 15. Thereby, the inverter 65 is cooled.

[0050] The centrifugal compressor 100 is provided with a seal member 63. The seal member 63 is provided between the first insertion hole 23 and the rotating shaft 50. The seal member 63 suppresses the leakage of air from the first impeller chamber 36 into the motor chamber 14c through the inside of the first insertion hole 23 and the first bearing holding portion 21. The seal member 63 is, for example, a seal ring.

[0051] The centrifugal compressor 100 is provided with a seal member 64. The seal member 64 is provided between the second insertion hole 26 and the rotating shaft 50. The seal member 64 suppresses the leakage of air from the second impeller chamber 41 into the motor chamber 14c through the inside of the second insertion hole 26 and the second bearing holding portion 25. The seal member 64 is, for example, a seal ring.

[0052] <Connection path> As shown in FIGS. 1 and 2, the centrifugal compressor 100 includes a connection path 70. The connection path 70 connects the first discharge port 39 and the second suction port 40 so that air flows from the first discharge port 39 toward the second suction port 40. The connection path 70 includes a first impeller housing connection path 101, a second impeller housing connection path 102, and a motor housing connection path 13b. Therefore, in the present embodiment, the connection path 70 is formed by the first impeller housing connection path 101, the second impeller housing connection path 102, and the motor housing connection path 13b.

[0053] The first compressor housing 11 has a first passage 11a. The first compressor housing 11 has a first passage defining surface 11b. The first passage defining surface 11b defines the first passage 11a. The first end of the first passage 11a is connected to the first discharge port 39. The second end of the first passage 11a is an end face on the side of the second plate 17 in the first compressor housing 11 and opens at a portion located radially outside the rotation axis 50 with respect to the first discharge chamber 37. The first passage defining surface 11b is a curved surface extending from the opening edge of the second end of the first passage 11a.

[0054] The second plate 17 has a second plate hole 17a. The second plate 17 has a second plate hole defining surface 17b. The second plate hole defining surface 17b defines the second plate hole 17a. The second plate hole defining surface 17b is continuous with the first passage defining surface 11b. That is, the second plate hole 17a communicates with the first passage 11a. The second plate hole 17a opens at both end faces in the thickness direction of the second plate 17. The second plate hole 17a is connected to the second end of the first passage 11a.

[0055] The first impeller housing connection path 101 is formed by the first passage 11a and the second plate hole 17a. That is, the first impeller housing connection path 101 is formed in the first impeller housing 10b. Therefore, the first impeller housing connection path 101 is formed inside the housing 10. The first end of the first impeller housing connection path 101 is connected to the first discharge port 39. And air flows from the first discharge port 39 into the first impeller housing connection path 101. Therefore, the first impeller housing connection path 101 is provided in the first impeller housing 10b and connected to the first discharge port 39. The second end of the first impeller housing connection path 101 opens at the end face on the side of the first plate 16 in the second plate 17 and at a portion located radially outside the rotation axis 50 than the first discharge chamber 37.

[0056] Here, the boundary L1 between the first end of the first impeller housing connection path 101 and the first discharge port 39 is shown by a two-dot chain line in FIG. 2. The portion corresponding to the boundary L1 between the first end of the first impeller housing connection path 101 and the first discharge port 39 in the first impeller housing 10b corresponds to the location where the first end of the pipe conventionally adopted for connecting the first discharge port 39 and the second suction port 40 is connected. The first impeller housing connection path 101 of the present embodiment extends from the portion corresponding to the location where the first end of the conventional pipe is connected.

[0057] The second compressor housing 12 has a second passage 12b. As shown in FIGS. 1, 3, and 4, the second passage 12b has a first axial path 401, a second axial path 402, and a radial path 403. The first axial path 401 is formed in the second impeller housing base 12a. That is, in the second impeller housing base 12a, the first axial path 401, which is an axial path constituting a part of the second passage 12b, is formed. The second impeller housing base 12a has a first axial path defining surface 401a that defines the first axial path 401. The first axial path 401 is located radially outside the rotation axis 50 from the second suction port 40 and extends in the axial direction of the rotation axis 50. The first axial path 401 penetrates the second impeller housing base 12a in the axial direction of the rotation axis 50. The first end of the first axial path 401 opens to the end face on the side of the third plate 18 in the second impeller housing base 12a. The second end of the first axial path 401 opens to the end face on the side opposite to the third plate 18 in the second impeller housing base 12a. The end face on the side opposite to the third plate 18 in the second impeller housing base 12a is the axial end face 12d, which is the end face located in the axial direction of the rotation axis 50 in the second impeller housing base 12a. Therefore, the first axial path 401 opens to the axial end face 12d.

[0058] The first axial path 401 includes a third suction port 401b, which is the opening at the first end, and a third discharge port 401c, which is the opening at the second end. That is, the second impeller housing 10c includes the third suction port 401b and the third discharge port 401c. In the second impeller housing base 12a, the third suction port 401b and the third discharge port 401c are open.

[0059] The second axial path 402 is formed in the second impeller housing base 12a. The first end of the second axial path 402 is connected to the second suction port 40. That is, the second passage 12b is provided in the second compressor housing 12 and connected to the second suction port 40. The second end of the second axial path 402 opens to the axial end face 12d. Therefore, the second suction port 40 extends axially from the second impeller chamber 41 along the rotation axis 50 and opens to the axial end face 12d through the second axial path 402. The axis of the second suction port 40 coincides with the axis of the second axial path 402. The second impeller housing base 12a has a second axial path defining surface 402a that defines the second axial path 402.

[0060] As shown in FIGS. 1 and 5, the second impeller housing cover 19 is manufactured by die casting. The second impeller housing cover 19 is connected to the axial end face 12d of the second impeller housing base 12a. The second impeller housing cover 19 closes the opening on the axial end face 12d side at the second suction port 40 and the opening on the axial end face 12d side at the first axial path 401.

[0061] As shown in FIG. 1, the second impeller housing cover 19 has a facing surface 19b that faces the axial end face 12d of the second impeller housing base 12a. That is, the second impeller housing cover 19 has a facing surface 19b that faces the second impeller housing base 12a in the axial direction of the rotation axis 50. The facing surface 19b is a flat surface.

[0062] On the opposing surface 19b of the second impeller housing cover portion 19, a guide portion 19d is formed. The guide portion 19d is in the shape of a groove. Thus, the second impeller housing 10c has the second impeller housing cover portion 19 in which the groove-shaped guide portion 19d is formed. In a state where the second impeller housing cover portion 19 is connected to the axial end face 12d of the second impeller housing base portion 12a, the inside of the guide portion 19d connects the second end of the first axial path 401 and the second end of the second axial path 402. In other words, the guide portion 19d is connected to the first axial path 401 via the third discharge port 401c. Between the inner surface 19c of the guide portion 19d and the axial end face 12d of the second impeller housing base portion 12a, there is a path 403. Therefore, between the second impeller housing cover portion 19 and the second impeller housing base portion 12a, a part of the second impeller housing connection path 102 is formed, and a path 403 is formed that extends in the radial direction of the rotating shaft 50 and directs the air from the first axial path 401 toward the second suction port 40. Thus, the guide portion 19d defines the path 403.

[0063] The inner surface 19c of the guide portion 19d has a first cover connection surface 191, a second cover connection surface 192, and a bottom surface 193. The bottom surface 193 is in the shape of a flat surface extending in the radial direction of the rotating shaft 50. The first cover connection surface 191 extends from the opening edge 19e of the guide portion 19d and is connected to the bottom surface 193. The first cover connection surface 191 extends from a portion of the opening edge 19e of the guide portion 19d located on the first axial path 401 side. The direction in which the first cover connection surface 191 extends from the opening edge 19e of the guide portion 19d toward the bottom surface 193 is curved so as to face a direction orthogonal to the axial direction of the first axial path 401 from the axial direction of the first axial path 401. The first cover connection surface 191 is curved so that the flow direction of the air that has passed through the first axial path 401 becomes the direction in which the path 403 extends from the extending direction of the first axial path 401. The first cover connection surface 191 smoothly connects the first axial path defining surface 401a and the bottom surface 193.

[0064] The second lid connection surface 192 extends from the opening edge 19e of the guide portion 19d and is connected to the bottom surface 193. The second lid connection surface 192 extends from a portion located on the second suction port 40 side at the opening edge 19e of the guide portion 19d. The direction in which the second lid connection surface 192 extends from the opening edge 19e of the guide portion 19d toward the bottom surface 193 is curved so as to face a direction orthogonal to the axial direction of the second axial path 402 from the axial direction of the second axial path 402. The second lid connection surface 192 is curved such that the flowing direction of the air that has passed through the path 403 becomes the direction in which it flows into the second suction port 40. The second lid connection surface 192 smoothly connects the second axial path defining surface 402a and the bottom surface 193.

[0065] The third plate hole 18a is formed in the third plate 18. The third plate 18 has a third plate hole defining surface 18b. The third plate hole defining surface 18b defines the third plate hole 18a. The hole diameter of the third plate hole 18a is the same as the hole diameter of the first axial path 401. The axis of the third plate hole 18a coincides with the axis of the first axial path 401. The third plate hole defining surface 18b is continuous with the first axial path defining surface 401a. The third plate hole 18a opens at both end faces in the thickness direction of the third plate 18. The third plate hole 18a is connected to the first end of the first axial path 401 and communicates with the third suction port 401b.

[0066] The second impeller housing connection path 102 is formed by the second passage 12b and the third plate hole 18a. That is, the second impeller housing 10c defines the second impeller housing connection path 102 that allows air to flow to the second suction port 40.

[0067] Here, the boundary L2 between the second impeller housing connection path 102 and the second suction port 40 is shown by a two-dot chain line in FIG. 1. A portion corresponding to the boundary L2 between the second impeller housing connection path 102 and the first suction port 35 in the second impeller housing 10c corresponds to a location where the second end of a pipe that has conventionally been employed to connect the first discharge port 39 and the second suction port 40 is connected. The second impeller housing connection path 102 of the present embodiment extends from a portion corresponding to the location where the second end of the conventional pipe is connected.

[0068] The second motor housing 15 has a connection hole 15d. The second motor housing 15 has a connection hole defining surface 15b. The connection hole defining surface 15b defines the connection hole 15d. The connection hole 15d extends in the axial direction of the second motor housing 15 and opens at both end faces in the axial direction of the second motor housing 15. The connection hole 15d is located radially outside the motor housing accommodation hole 15c with respect to the rotation axis 50. The direction in which the connection hole 15d extends coincides with the axial direction of the rotation axis 50. The axis of the connection hole 15d coincides with the axis of the third plate hole 18a. The hole diameter of the connection hole 15d is the same as the hole diameter of the third plate hole 18a. The connection hole defining surface 15b is continuous with the third plate hole defining surface 18b. The connection hole 15d is connected to the third plate hole 18a.

[0069] The first plate 16 has a first plate hole 16a. The first plate 16 has a first plate hole defining surface 16b. The first plate hole defining surface 16b defines the first plate hole 16a. The aperture diameter of the first plate hole 16a is the same as the aperture diameters of the connection hole 15d and the second plate hole 17a. The axis of the first plate hole 16a coincides with the axes of the connection hole 15d and the second plate hole 17a. The first plate hole defining surface 16b is continuous with the connection hole defining surface 15b and the second plate hole defining surface 17b. The first plate hole 16a opens at both end faces in the thickness direction of the first plate 16. The first end of the first plate hole 16a is connected to the end of the second plate hole 17a in the axial direction that is not connected to the first passage 11a. The second end of the first plate hole 16a is connected to the first end of the connection hole 15d.

[0070] The connection hole 15d and the first plate hole 16a form a motor housing connection path 13b. The connection hole defining surface 15b and the first plate hole defining surface 16b form a third passage defining surface 13c that defines the motor housing connection path 13b. Thus, the connection path forming housing 13 defines the motor housing connection path 13b. The motor housing connection path 13b is formed through the motor housing 10a and connects the first impeller housing connection path 101 and the second impeller housing connection path 102. The motor housing connection path 13b is formed through the second motor housing 15. The first end of the third plate hole 18a is connected to the motor housing connection path 13b. The third suction port 401b sucks air in the axial direction of the rotary shaft 50 facing the motor housing connection path 13b. The cooling medium path 13a is provided between the motor 20 and the motor housing connection path 13b in the radial direction of the rotary shaft 50.

[0071] Thus, the connection path 70 is formed by the first impeller housing connection path 101, the second impeller housing connection path 102, and the motor housing connection path 13b. The connection path 70 is formed by the first impeller housing 10b, the second impeller housing 10c, and the connection path forming housing 13. That is, the connection path 70 is configured by sequentially stacking the first impeller housing 10b, the motor housing 10a, and the second impeller housing 10c in the axial direction of the rotation shaft 50.

[0072] The centrifugal compressor 100 includes a third seal member 83. The third seal member 83 is interposed between the second plate 17 and the first plate 16. The third seal member 83 is, for example, an O-ring. The third seal member 83 seals between the second plate 17 and the first plate 16. In the centrifugal compressor 100, the first impeller housing 10b and the motor housing 10a are connected with the third seal member 83 interposed therebetween. Thereby, the first impeller housing connection path 101 and the motor housing connection path 13b communicate with each other.

[0073] The centrifugal compressor 100 has a fifth seal member 85 and an eighth seal member 88. The fifth seal member 85 and the eighth seal member 88 are interposed between the motor housing 10a and the third plate 18. The fifth seal member 85 is interposed between the second motor housing 15 and the third plate 18. The eighth seal member 88 is interposed between the first motor housing 14 and the third plate 18. The fifth seal member 85 and the eighth seal member 88 are, for example, O-rings. The fifth seal member 85 seals between the second motor housing 15 and the third plate 18. The eighth seal member 88 seals between the first motor housing 14 and the third plate 18. That is, the fifth seal member 85 and the eighth seal member 88 seal between the motor housing 10a and the third plate 18. In the centrifugal compressor 100, the motor housing 10a and the second impeller housing 10c are connected with the fifth seal member 85 and the eighth seal member 88 interposed therebetween. Thereby, the second impeller housing connection path 102 and the motor housing connection path 13b communicate with each other.

[0074] Note that the centrifugal compressor 100 includes a first seal member 81, a second seal member 82, a fourth seal member 84, a sixth seal member 86, and a seventh seal member 87. The first seal member 81 seals between the first compressor housing 11 and the second plate 17. The second seal member 82 seals between the third plate 18 and the second compressor housing 12. The fourth seal member 84 seals between the second motor housing 15 and the first plate 16. The sixth seal member 86 seals between the second impeller housing base portion 12a and the second impeller housing lid portion 19. The seventh seal member 87 seals between the first plate 16 and the first motor housing 14. The first seal member 81, the second seal member 82, the fourth seal member 84, the sixth seal member 86, and the seventh seal member 87 are, for example, O-rings.

[0075] [Operation of the Present Embodiment] The air inhaled into the first impeller chamber 36 through the first suction port 35 is accelerated by the rotation of the first impeller 61 and then sent into the first diffuser flow path 38, and is pressurized by passing through the first diffuser flow path 38. Then, the air that has passed through the first diffuser flow path 38 is discharged into the first discharge chamber 37. The air discharged into the first discharge chamber 37 is discharged from the first discharge port 39. Therefore, the first discharge port 39 discharges the air compressed by the rotation of the first impeller 61.

[0076] The air discharged from the first discharge port 39 flows from the first discharge port 39 into the first impeller housing connection path 101. The air flowing through the first impeller housing connection path 101 is introduced into the motor housing connection path 13b. The air introduced into the motor housing connection path 13b is cooled by the cooling water flowing through the cooling medium path 13a when passing through the connection hole 15d in the motor housing connection path 13b. That is, the cooling water flowing through the cooling medium path 13a cools the motor 20 and also cools the air flowing through the connection path 70.

[0077] The air that has passed through the motor housing connection path 13b is introduced into the first axial path 401 through the third suction port 401b. In other words, the third suction port 401b sucks air in the axial direction of the rotation shaft 50 facing the motor housing connection path 13b. The air that has passed through the first axial path 401 is introduced into the path 403 through the third discharge port 401c. In other words, the third discharge port 401c is open so as to discharge the air inhaled from the third suction port 401b toward the guide portion 19d.

[0078] The air introduced into the path 403 flows smoothly along the first lid connection surface 191. In other words, the guide portion 19d guides the air inhaled in the axial direction of the rotating shaft 50 from the third suction port 401b in the radial direction of the rotating shaft 50 so as to approach the second suction port 40. Specifically, when air flows from the first path 401 into the path 403, as the air flows along the first lid connection surface 191, the flow direction of the air changes from the axial direction of the first path 401 to the direction in which the path 403 extends. Therefore, the first lid connection surface 191 changes the flow direction of the air from the direction along the first path defining surface 401a to the direction along the bottom surface 193. The second impeller housing lid portion 19 guides the air flowing from the first path 401 into the path 403 by the first lid connection surface 191, thereby suppressing a sudden change in the flow direction in the air flow. Thereby, the second impeller housing lid portion 19 suppresses the formation of vortices when the flow direction of the air changes from the axial direction of the first path 401 to the direction in which the path 403 extends. In this way, the air flowing into the path 403 from the first path 401 is suppressed from forming vortices.

[0079] The air introduced into the path 403 is introduced into the second path 402 after passing through the path 403. The air flowing through the path 403 flows smoothly along the second lid connection surface 192. In other words, the guide portion 19d guides the air flowing in the radial direction of the rotating shaft 50 further in the axial direction of the rotating shaft 50 toward the second suction port 40. Specifically, when air flows from the path 403 into the second path 402, as the air flows along the second lid connection surface 192, the flow direction of the air changes from the direction in which the path 403 extends to the axial direction of the second path 402. Therefore, the second lid connection surface 192 changes the flow direction of the air from the direction along the bottom surface 193 to the direction along the second path 402. The second impeller housing lid portion 19 guides the air flowing from the path 403 into the second path 402 by the second lid connection surface 192, thereby suppressing a sudden change in the flow direction in the air flow. Thereby, the second impeller housing lid portion 19 suppresses the formation of vortices when the flow direction of the air changes from the direction in which the path 403 extends to the axial direction of the second path 402. In this way, the air flowing toward the second suction port 40 from the path 403 is suppressed from forming vortices.

[0080] As described above, the third discharge port 401c and the second suction port 40 are connected by the guide portion 19d. In other words, the second impeller housing lid portion 19 is formed with a groove-shaped guide portion 19d that opens so as to allow air to flow from the third discharge port 401c toward the second suction port 40.

[0081] The air that has passed through the second passage 402 is inhaled into the second impeller chamber 41 through the second suction port 40. The air inhaled into the second impeller chamber 41 is accelerated by the rotation of the second impeller 62 and then sent into the second diffuser flow path 43, and is pressurized by passing through the second diffuser flow path 43. Then, the air that has passed through the second diffuser flow path 43 is discharged into the second discharge chamber 42. The air discharged into the second discharge chamber 42 is discharged from the second discharge port 44. Therefore, the second discharge port 44 discharges the air compressed by the rotation of the second impeller 62. The air discharged from the second discharge port 44 is supplied to the fuel cell stack 46 via the supply pipe 45. Oxygen contained in the air supplied to the fuel cell stack 46 contributes to the power generation of the fuel cell stack 46.

[0082] [Effects of the Present Embodiment] The effects of the present embodiment will be described. (1) The connection path 70 is constituted by the first impeller housing 10b, the motor housing 10a, and the second impeller housing 10c that the housing 10 has. That is, the connection path 70 is formed inside the housing 10. Therefore, for example, in the centrifugal compressor 100, in a configuration where the first discharge port 39 and the second suction port 40 are connected by attaching a pipe, which is a separate member from the housing 10, to the housing 10, no gap is formed between the housing 10 and the pipe. Thus, the centrifugal compressor 100 does not needlessly increase in size by the amount of the gap formed between the housing 10 and the pipe. As a result, an increase in the size of the centrifugal compressor 100 can be suppressed. Also, the connection path 70 can be constituted simply by sequentially laminating the first impeller housing 10b, the motor housing 10a, and the second impeller housing 10c in the axial direction of the rotating shaft 50. Therefore, a structure that can absorb the dimensional tolerance generated between the housing 10 and the pipe when attaching the pipe to the housing 10, for example, does not require a device such as providing it on the pipe. For this reason, the productivity of the centrifugal compressor 100 can be improved. From the above, it is possible to improve productivity while suppressing an increase in the size of the centrifugal compressor 100.

[0083] (2) The cooling medium path 13a is provided between the motor 20 and the motor housing connection path 13b in the radial direction of the rotating shaft 50. According to this, the cooling water flowing through the cooling medium path 13a can cool not only the motor 20 but also the air flowing through the motor housing connection path 13b. Therefore, the air cooled by the cooling water can be inhaled into the second impeller chamber 41 through the motor housing connection path 13b, the second impeller housing connection path 102, and the second suction port 40. The air cooled by the cooling water has a lower density compared to the non-cooled air. That is, when the air is cooled before being inhaled into the second impeller chamber 41, the mass of the air inhaled into the second impeller chamber 41 increases. Therefore, the second impeller 62 can compress a larger mass of air compared to the case of compressing non-cooled air. As a result, the compression efficiency of the air accompanying the rotation of the second impeller 62 can be improved.

[0084] (3) For example, when the cooling medium passage 13a is formed by a single housing member, in order to manufacture such a housing member, it is necessary to use a casting method using a core. The manufacturing method using a core incurs higher manufacturing costs compared to the manufacturing method without using a core. Therefore, the cooling medium passage 13a is defined such that cooling water flows between the first motor housing 14 and the second motor housing 15. Each of the first motor housing 14 and the second motor housing 15 that defines the cooling medium passage 13a does not need to be manufactured by a casting method using a core. That is, in the motor housing 10a having the first motor housing 14 and the second motor housing 15, it is possible to form the cooling medium passage 13a by a manufacturing method without using a core. As a result, the above configuration can form the cooling medium passage 13a in the motor housing 10a while suppressing manufacturing costs.

[0085] (4) The third suction port 401b sucks the air that has flowed through the motor housing connection passage 13b in the axial direction of the rotating shaft 50. The guide portion 19d guides the air sucked in the axial direction of the rotating shaft 50 from the third suction port 401b in the radial direction of the rotating shaft 50 so as to approach the second suction port 40. Further, the guide portion 19d guides the air flowing in the radial direction of the rotating shaft 50 in the axial direction of the rotating shaft 50 toward the second suction port 40. As a result, the guiding of the air by the guide portion 19d can suppress the formation of vortices when the air changes its flow direction. Therefore, since the second impeller housing 10c has the guide portion 19d, the pressure loss of the air flowing from the third suction port 401b toward the second suction port 40 can be reduced, and thus the compression efficiency of the air accompanying the rotation of the second impeller 62 can be improved.

[0086] (5) For example, consider a case where an air flow path from the third suction port 401b to the second suction port 40 is formed by a single housing member. Here, the second suction port 40 extends in the axial direction of the rotary shaft 50 from the second impeller chamber 41. The flow path from the third suction port 401b to the third discharge port 401c extends in the axial direction of the rotary shaft 50 from the motor housing connection path 13b outside the radial direction of the rotary shaft 50 with respect to the second suction port 40. That is, the flow path through which air flows from the third discharge port 401c to the second suction port 40 extends in the radial direction of the rotary shaft 50. In order to manufacture such a housing member in which the flow path from the third suction port 401b to the third discharge port 401c and the flow path from the third discharge port 401c to the second suction port 40 are formed, it may be necessary to use a casting method using a core, which may increase the manufacturing cost.

[0087] Therefore, the second impeller housing 10c has a second impeller housing base portion 12a and a second impeller housing lid portion 19. In the second impeller housing base portion 12a, a flow path connecting the second suction port 40 and the third suction port 401b and the third discharge port 401c is formed. The second impeller housing lid portion 19 is connected to the surface of the second impeller housing base portion 12a on which the third discharge port 401c opens. Thereby, the second impeller housing lid portion 19 closes the opening at one end side of the second suction port 40 and the opening by the third discharge port 401c. And a flow path connecting the third discharge port 401c and the second suction port 40, which is defined by the guide portion 19d and the second impeller housing base portion 12a, is formed between the second impeller housing lid portion 19 and the second impeller housing base portion 12a. According to this, unlike the case where an air flow path from the third suction port 401b to the second suction port 40 is formed by a single housing member, it is not necessary to use a casting method using a core, so that an increase in manufacturing cost can be avoided.

[0088] (6) The inverter 65 is provided on the outer surface 10e of the housing. That is, the cooling water flowing through the cooling medium passage 13a can cool the motor 20, the air flowing through the connection passage 70, and the inverter 65. That is, while forming the connection passage 70 inside the housing 10 and providing the inverter 65 on the outer surface of the housing 10, the configuration can cool the motor 20, the air flowing through the connection passage 70, and the inverter 65 simultaneously with a single cooling medium passage 13a while miniaturizing the centrifugal compressor 100. As a result, the centrifugal compressor 100 can improve the compression efficiency by the second impeller 62 while suppressing an increase in size, and can efficiently dissipate the heat generated during the operation of the centrifugal compressor 100.

[0089] (7) A plurality of annular fins 14d extending along the outer peripheral surface of the peripheral wall 14b are formed on the outer peripheral surface of the first motor housing 14. For this reason, the cooling water flowing through the cooling medium passage 13a flows in the circumferential direction of the first motor housing 14 and the second motor housing 15 along each fin 14d. For this reason, efficient heat exchange can be performed with the first motor housing 14, the second motor housing 15, and the inverter housing 66. That is, the cooling water can efficiently cool the motor 20, the air flowing through the cooling medium passage 13a, and the inverter 65 by flowing along each fin 14d. Here, for example, consider a configuration in which an annular fin 14d extending along the outer peripheral surface of the peripheral wall 14b of the first motor housing 14 protrudes into the cooling medium passage 13a and the connection passage 70 is formed inside the housing 10, and this is configured by a single housing member. In order to manufacture such a housing member, it is necessary to manufacture it by a casting method using a core, so the manufacturing cost increases. Therefore, in the present embodiment, the first motor housing 14 is formed as a separate member from the second motor housing 15. According to this, it is not necessary to manufacture each of the first motor housing 14 and the second motor housing 15 by a casting method using a core. Therefore, while suppressing the manufacturing cost, it is possible to achieve a configuration in which an annular fin 14d extending along the outer peripheral surface of the peripheral wall 14b of the first motor housing 14 protrudes into the cooling medium passage 13a and the connection passage 70 is formed inside the housing 10.

[0090] [Modification Example] In addition, the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

[0091] ○ The guide portion 19d may not be formed on the opposing surface 19b of the second impeller housing lid portion 19. In this case, for example, a recess extending in the radial direction of the rotary shaft 50 is formed on the axial end surface 12d of the second impeller housing base portion 12a, and the recess may function as the guide portion 19d. That is, the second impeller housing base portion 12a may have the guide portion 19d.

[0092] ○ The second impeller housing 10c may not include the second impeller housing lid portion 19. In this case, the second impeller housing 10c is formed by the second impeller housing base portion 12a and the third plate 18. Also, in this case, the first axial path 401 and the second suction port 40 are connected through the inside of the second impeller housing base portion 12a without opening at the axial end surface 12d. That is, in this case, the second impeller housing 10c may not include the third discharge port 401c.

[0093] ○ The second axial path 402 may not be formed in the second impeller housing base portion 12a. In this case, the second suction port 40 is directly connected to the path 403. ○ The motor housing 10a may not include the first motor housing 14 and the second motor housing 15. That is, the motor housing 10a may be composed of a single housing member. In this case, the cooling medium path 13a is formed inside the housing 10.

[0094] ○ The cooling medium path 13a may not be provided between the motor 20 and the motor housing connection path 13b in the radial direction of the rotary shaft 50. ○ The centrifugal compressor 100 may not include the cooling medium path 13a.

[0095] ○ The centrifugal compressor 100 may be configured such that one thin plate fin extending spirally is provided on the outer peripheral surface of the peripheral wall 14b of the first motor housing 14. ○ Fins may not be provided on the outer peripheral surface of the peripheral wall 14b of the first motor housing 14. In this case, the cooling water flowing through the cooling medium passage 13a may flow in the axial direction of the peripheral wall 14b along the outer peripheral surface of the peripheral wall 14b of the first motor housing 14.

[0096] ○ The cooling medium flowing through the cooling medium passage 13a may be other than cooling water, and may be, for example, a refrigerant or air. ○ The inverter 65 may not be provided on the outer surface 10e of the housing.

[0097] ○ The fluid compressed by the centrifugal compressor 100 is not limited to air. Therefore, the application target and the fluid to be compressed of the centrifugal compressor 100 are arbitrary. For example, the centrifugal compressor 100 may be used in an air conditioner, and the fluid to be compressed may be a refrigerant. Further, the mounting target of the centrifugal compressor 100 is not limited to a vehicle and is arbitrary.

Description of Reference Numerals

[0098] 10…housing, 10a…motor housing, 10b…first impeller housing, 10c…second impeller housing, 12a…second impeller housing base, 13a…cooling medium passage, 13b…motor housing connection passage, 14…first motor housing, 14c…motor chamber, 15…second motor housing, 19…second impeller housing lid, 19d…guide portion, 20…motor, 35…first suction port, 36…first impeller chamber, 39…first discharge port, 40…second suction port, 41…second impeller chamber, 44…second discharge port, 50…rotating shaft, 51…rotor, 52…stator, 61…first impeller, 62…second impeller, 70…connection passage, 100…centrifugal compressor, 101…first impeller housing connection passage, 102…second impeller housing connection passage, 401b…third suction port, 401c…third discharge port.

Claims

1. A rotating shaft, A motor for rotating the rotating shaft, A first impeller that rotates integrally with the rotating shaft to compress fluid, A second impeller provided on the opposite side of the first impeller with the motor interposed therebetween with respect to the rotating shaft and rotating integrally with the rotating shaft, A housing having a first impeller housing that defines a first impeller chamber for accommodating the first impeller, a first suction port for sucking fluid into the first impeller chamber, and a first discharge port for discharging the fluid compressed by the rotation of the first impeller, a motor housing that defines a motor chamber for accommodating the motor, and a second impeller housing that defines a second impeller chamber for accommodating the second impeller, and having a second suction port for sucking fluid into the second impeller chamber and a second discharge port for discharging the fluid compressed by the rotation of the second impeller, A centrifugal compressor comprising a connection path that connects the first discharge port and the second suction port so that fluid flows from the first discharge port toward the second suction port, The connection path includes a first impeller housing connection path provided in the first impeller housing and connected to the first discharge port, a second impeller housing connection path provided in the second impeller housing and connected to the second suction port, and a motor housing connection path formed through the motor housing and connecting the first impeller housing connection path and the second impeller housing connection path, The centrifugal compressor is characterized in that the first impeller housing, the motor housing, and the second impeller housing are sequentially stacked in the axial direction of the rotating shaft.

2. The motor housing includes a cooling medium path through which a cooling medium for cooling the motor flows, The centrifugal compressor according to claim 1, wherein the cooling medium path is provided between the motor and the motor housing connection path in the radial direction of the rotating shaft.

3. The motor has a cylindrical stator and a rotor provided on the rotating shaft and rotating integrally with the rotating shaft, The motor housing has a first motor housing with the stator fixed to the inner peripheral surface, And a second motor housing through which the motor housing connection path is formed. The centrifugal compressor according to claim 2, wherein the cooling medium passage is defined such that a cooling medium flows between the first motor housing and the second motor housing.

4. The second impeller housing has a third suction port that sucks fluid in the axial direction facing the motor housing connection passage, and guides the fluid sucked in the axial direction from the third suction port in the radial direction of the rotation axis so as to approach the second suction port, and further guides the fluid flowing in the radial direction in the axial direction toward the second suction port. The centrifugal compressor according to claim 1, characterized by having a guide portion.

5. The second impeller housing has a second impeller housing base portion in which the third suction port, the second suction port, and the second discharge port are opened, and a third discharge port that discharges the fluid sucked from the third suction port toward the guide portion is opened; The centrifugal compressor according to claim 4, further comprising: a second impeller housing lid portion that connects the third discharge port and the second suction port and has a groove-shaped guide portion that is opened so as to allow fluid to flow from the third discharge port toward the second suction port.

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