WO2024062714A1

WO2024062714A1 - Centrifugal compressor

Info

Publication number: WO2024062714A1
Application number: PCT/JP2023/024053
Authority: WO
Inventors: 森英文; 鈴木潤也
Original assignee: 株式会社豊田自動織機
Priority date: 2022-09-20
Filing date: 2023-06-28
Publication date: 2024-03-28
Also published as: JP2024043954A

Abstract

In a centrifugal compressor (10), the speed of air flowing into a second insertion hole (26) from a gap (70) between a back surface (43a) of a second impeller (43) and a second plate (16) is increased as a result of passing through a throttle section (61). As a consequence, the pressure of the air after passing through the throttle section (61) becomes lower than the pressure of the air before passing through the throttle section (61). A communication section (62) extends in a direction intersecting the flow direction of the air that has passed through the throttle section (61). Therefore, the air that has passed through the throttle section (61) is unlikely to flow into a motor chamber (18) through the communication section (62). A discharge passage (63) extends in the flow direction of the air that has passed through the throttle section (61). As a result, the air that has passed through the throttle section (61) easily flows into the discharge passage (63). Therefore, the air flowing into the second insertion hole (26) from the gap (70) between the back surface (43a) of the second impeller (43) and the second plate (16) is easily discharged through the discharge passage (63) to the outside of a housing (11) while increasing in pressure.

Description

centrifugal compressor

The present invention relates to a centrifugal compressor that compresses air supplied to a fuel cell stack.

For example, as disclosed in Patent Document 1, a centrifugal compressor that compresses air supplied to a fuel cell stack includes a rotating body including an impeller. The impeller compresses the air supplied to the fuel cell stack. Further, the centrifugal compressor includes a motor and a housing. The motor rotates the rotating body. The housing has an impeller chamber, a motor chamber, a partition wall, and a discharge chamber. The impeller chamber houses the impeller. The motor chamber houses the motor. The partition wall partitions the impeller room and the motor room. Air compressed by the impeller is discharged into the discharge chamber. A supply flow path that supplies air to the fuel cell stack is connected to the discharge chamber. An insertion hole through which the rotating body is inserted is formed in the partition wall.

Incidentally, in such a centrifugal compressor, it is desired to cool the motor in order to improve the durability of the centrifugal compressor. Therefore, it has been considered to cool the motor by introducing a portion of the air compressed by the impeller into the motor chamber at a temperature lower than the temperature of the air discharged into the discharge chamber.

JP 2015-155696 A

In such a centrifugal compressor, a part of the air compressed by the impeller and discharged into the discharge chamber may flow into the gap between the back surface of the impeller and the partition wall. Then, there is a possibility that air flowing into the gap between the back surface of the impeller and the partition wall may enter the motor chamber through the insertion hole. The temperature of the air compressed by the impeller and discharged into the discharge chamber is high. Therefore, if a portion of the air compressed by the impeller and discharged into the discharge chamber enters the motor chamber through the insertion hole, the motor will be warmed by the air that has entered the motor chamber. As a result, it may become difficult to cool the motor. This reduces the durability of the centrifugal compressor.

A centrifugal compressor that solves the above problems includes a rotating body including an impeller that compresses air supplied to a fuel cell stack, a motor that rotates the rotating body, an impeller chamber that accommodates the impeller, and an impeller chamber that accommodates the motor. a motor chamber, a partition wall that partitions the impeller chamber and the motor chamber and is formed with an insertion hole through which the rotating body is inserted; a housing having a discharge chamber to which a supply flow path for supplying air is connected, and a part of the air compressed by the impeller is kept at a temperature lower than the temperature of the air discharged into the discharge chamber. A centrifugal compressor that cools the motor by being introduced into the motor chamber, wherein the air gap is formed between the insertion hole and the rotating body and between the back surface of the impeller and the partition wall. a constriction part that constricts the air flowing from the through hole into the through hole; a communication section that communicates with the motor chamber; and a discharge passage formed in the partition wall and extending in the flow direction of the air that has passed through the constriction section, increasing the pressure of the air that has passed through the constriction section and discharging it to the outside of the housing. It is equipped with.

According to this, the speed of air flowing into the insertion hole from the gap between the back surface of the impeller and the partition wall increases by passing through the constriction part. Thereby, the pressure of the air after passing through the constriction section is lower than the pressure of the air before passing through the constriction section. The communication portion extends in a direction intersecting the flow direction of the air that has passed through the constriction portion. Therefore, it is difficult for the air that has passed through the throttle section to flow into the motor chamber via the communication section. The discharge passage extends in the flow direction of the air that has passed through the constriction section. Therefore, the air that has passed through the constriction part easily flows into the discharge passage. Therefore, the air flowing into the insertion hole from the gap between the back surface of the impeller and the partition wall is easily discharged to the outside of the housing while increasing the pressure through the discharge passage. As a result, a portion of the air compressed by the impeller and discharged into the discharge chamber is prevented from entering the motor chamber through the insertion hole. Therefore, a part of the air compressed by the impeller and discharged into the discharge chamber enters the motor chamber through the insertion hole, and the problem of the motor being warmed by the air entering the motor chamber is less likely to occur. Become. Therefore, by introducing a portion of the air compressed by the impeller into the motor chamber at a temperature lower than the temperature of the air discharged into the discharge chamber, the motor can be efficiently cooled. As a result, the durability of the centrifugal compressor can be improved.

In the centrifugal compressor, an outer circumferential surface of a portion of the rotating body located inside the insertion hole has a first outer circumferential surface and a first outer circumferential surface that is located closer to the motor chamber than the first outer circumferential surface. a second outer circumferential surface having an outer diameter smaller than The inner circumferential surface of the insertion hole has a first inner circumferential surface extending along the first outer circumferential surface, and a second inner circumferential surface extending along the second outer circumferential surface and having an inner diameter smaller than the first inner circumferential surface. and a second stepped surface that connects the first inner circumferential surface and the second inner circumferential surface and extends along the first stepped surface, and the constricted portion has a The communication portion is a gap between the first outer peripheral surface and the first inner peripheral surface, and the communication portion is a gap between the first step surface and the second step surface, and a gap between the second outer peripheral surface and the second inner peripheral surface. The end portion of the discharge passage opposite to the outside of the housing includes a gap between the first outer circumferential surface and the first inner circumferential surface. It is preferable that they face each other in the axial direction.

Such a configuration includes a constriction portion formed between the insertion hole and the rotating body, a communication portion formed between the insertion hole and the rotating body, and a discharge passage formed in the partition wall. This is suitable as a configuration for a centrifugal compressor.

In the centrifugal compressor, it is preferable that the throttle section lowers the pressure of air flowing from the gap into the insertion hole than the pressure inside the motor chamber.
According to this, the throttle section makes the pressure of the air flowing into the insertion hole from the gap between the back surface of the impeller and the partition wall lower than the pressure inside the motor chamber. Therefore, it is possible to further prevent part of the air compressed by the impeller and discharged into the discharge chamber from entering the motor chamber through the insertion hole.

This invention makes it possible to improve the durability of centrifugal compressors.

It is a sectional view of the centrifugal compressor in an embodiment. FIG. 2 is an enlarged cross-sectional view of a portion of the centrifugal compressor. FIG. 3 is an enlarged cross-sectional view of a portion of a centrifugal compressor in another embodiment.

An embodiment of a centrifugal compressor will be described below with reference to FIGS. 1 and 2. Note that the centrifugal compressor of the embodiment described below is installed in a fuel cell vehicle. A centrifugal compressor compresses the air supplied to the fuel cell stack.

<Basic configuration of centrifugal compressor 10>
As shown in FIG. 1, the centrifugal compressor 10 includes a housing 11. As shown in FIG. The housing 11 is made of a metal material, for example, aluminum. 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 third plate 17 .

The motor housing 12 extends in a cylindrical shape. The first plate 15 is connected to one end of the motor housing 12 on the opening side. The first plate 15 closes one opening of the motor housing 12. The second plate 16 is connected to the other open end of the motor housing 12 . The second plate 16 closes the other opening of the motor housing 12. A motor chamber 18 is defined by the motor housing 12, the first plate 15, and the second plate 16. Therefore, the housing 11 has a motor chamber 18.

The centrifugal compressor 10 includes a motor 20. The motor 20 is housed in the motor chamber 18. Therefore, motor chamber 18 accommodates motor 20. Motor housing 12 surrounds motor 20.

The centrifugal compressor 10 includes a first bearing holding section 21. The first bearing holding portion 21 projects into the motor chamber 18 from the center of the first plate 15 . Therefore, the first plate 15 has the first bearing holding portion 21 . The first bearing holding portion 21 has a cylindrical shape.

A chamber-forming recess 22 is formed on the end surface of the first plate 15 on the side opposite to the motor housing 12. The chamber forming recess 22 has a circular hole shape. The inside of the first bearing holding portion 21 penetrates the first plate 15 and opens to the bottom surface of the chamber forming recess 22 . The axis of the chamber-forming recess 22 and the axis of the first bearing holding part 21 coincide.

The third plate 17 is connected to the end surface of the first plate 15 on the opposite side from the motor housing 12. A first insertion hole 23 is formed in the center of the third plate 17 . The axis of the first insertion hole 23 coincides with the axis of the chamber forming recess 22 and the axis of the first bearing holding part 21 . A thrust bearing housing chamber 24 is defined by the chamber forming recess 22 and the third plate 17. The thrust bearing housing chamber 24 communicates with the inside of the first bearing holding section 21 . Further, the thrust bearing housing chamber 24 communicates with the first insertion hole 23 .

The centrifugal compressor 10 has a second bearing retaining portion 25. The second bearing retaining portion 25 protrudes from the center of the second plate 16 into the motor chamber 18. Therefore, the second plate 16 has the second bearing retaining portion 25. The second bearing retaining portion 25 is cylindrical.

A second insertion hole 26 is formed in the center of the second plate 16. The second insertion hole 26 communicates with the inside of the second bearing holding portion 25 . The axis of the second insertion hole 26 coincides with the axis of the second bearing holding part 25.

The first compressor housing 13 is cylindrical and has a circular first intake port 27 through which air is sucked. The first compressor housing 13 is connected to the end surface of the third plate 17 opposite to the first plate 15 with the axis of the first suction port 27 aligned with the axis of the first insertion hole 23. . The first suction port 27 opens at an end surface of the first compressor housing 13 on the opposite side from the third plate 17 . Air purified by an air cleaner (not shown) flows through the first intake port 27 .

The centrifugal compressor 10 includes a first impeller chamber 28, a first discharge chamber 29, and a first diffuser flow path 30. The first impeller chamber 28 , the first discharge chamber 29 , and the first diffuser flow path 30 are formed between the first compressor housing 13 and the third plate 17 . Therefore, the housing 11 has a first impeller chamber 28 . The first plate 15 and the third plate 17 constitute a partition wall that partitions the first impeller chamber 28 and the motor chamber 18. The first impeller chamber 28 communicates with the first suction port 27 . The first discharge chamber 29 extends around the first impeller chamber 28 and around the axis of the first suction port 27 . The first diffuser flow path 30 communicates the first impeller chamber 28 and the first discharge chamber 29. The first impeller chamber 28 communicates with the first insertion hole 23 .

The centrifugal compressor 10 has a first discharge passage 31. A first end of the first discharge passage 31 is connected to the first discharge chamber 29. A second end of the first discharge passage 31 opens to the outer peripheral surface of the first compressor housing 13.

The second compressor housing 14 is cylindrical and has a circular second intake port 32 through which air is sucked. The second compressor housing 14 is connected to the end surface of the second plate 16 opposite to the motor housing 12 with the axis of the second suction port 32 aligned with the axis of the second insertion hole 26 . The second suction port 32 opens at an end surface of the second compressor housing 14 on the opposite side from the second plate 16 .

The centrifugal compressor 10 includes a second impeller chamber 33, a second discharge chamber 34, and a second diffuser flow path 35. The second impeller chamber 33 , the second discharge chamber 34 , and the second diffuser flow path 35 are formed between the second compressor housing 14 and the second plate 16 . Therefore, the housing 11 has a second impeller chamber 33. The second plate 16 constitutes a partition wall that partitions the second impeller chamber 33 and the motor chamber 18. The second impeller chamber 33 communicates with the second suction port 32 . The second discharge chamber 34 extends around the second impeller chamber 33 and around the axis of the second suction port 32 . The second diffuser flow path 35 communicates the second impeller chamber 33 and the second discharge chamber 34. The second impeller chamber 33 communicates with the second insertion hole 26 .

The centrifugal compressor 10 has a second discharge passage 36. A first end of the second discharge passage 36 communicates with the second discharge chamber 34 . A second end of the second discharge passage 36 opens to the outer peripheral surface of the second compressor housing 14 . A supply pipe 37 is connected to the second discharge passage 36 . Supply piping 37 is connected to fuel cell stack 38 . A first end of the supply pipe 37 is connected to the second discharge passage 36 . A second end of the supply pipe 37 is connected to a fuel cell stack 38. The second discharge chamber 34 is connected to a fuel cell stack 38 via a second discharge passage 36 and a supply pipe 37.

The centrifugal compressor 10 is equipped with a connection pipe 39. A first end of the connecting pipe 39 communicates with the first discharge passage 31 . A second end of the connecting pipe 39 communicates with the second suction port 32 . Air discharged from the first discharge chamber 29 to the first discharge passage 31 flows within the connection pipe 39 . The air that has passed through the connection pipe 39 is then sucked into the second impeller chamber 33 via the second suction port 32.

The centrifugal compressor 10 includes a rotating body 40. The rotating body 40 includes a rotating shaft 41 , a first impeller 42 , a second impeller 43 , and a support section 44 . The rotating shaft 41 is housed within the housing 11.

The rotating shaft 41 extends along the axis of the motor housing 12 and crosses the motor chamber 18. The axial direction of the rotating shaft 41 coincides with the axial direction of the motor housing 12. The first end of the rotating shaft 41 projects from the motor chamber 18 into the first impeller chamber 28 by passing through the inside of the first bearing holding section 21, the thrust bearing housing chamber 24, and the first insertion hole 23. . Therefore, the first insertion hole 23 is an insertion hole through which the rotating body 40 is inserted. In this way, the housing 11 has a partition wall that partitions the first impeller chamber 28 and the motor chamber 18 and is formed with the first insertion hole 23 through which the rotating body 40 is inserted.

The second end of the rotating shaft 41 projects from the motor chamber 18 into the second impeller chamber 33 through the inside of the second bearing holding section 25 and the second insertion hole 26 . Therefore, the second insertion hole 26 is an insertion hole through which the rotating body 40 is inserted. In this way, the housing 11 has a partition wall that partitions the second impeller chamber 33 and the motor chamber 18 and is formed with the second insertion hole 26 through which the rotating body 40 is inserted.

The first impeller 42 is connected to the first end of the rotating shaft 41. The first impeller 42 is housed in the first impeller chamber 28 . Therefore, the first impeller chamber 28 accommodates the first impeller 42 . The first impeller 42 compresses the air sucked into the first impeller chamber 28 by rotating integrally with the rotating shaft 41. Therefore, the first impeller 42 is an impeller that compresses air. Therefore, the first impeller chamber 28 is an impeller chamber that accommodates an impeller.

The second impeller 43 is connected to the second end of the rotating shaft 41. The second impeller 43 is housed in the second impeller chamber 33. Therefore, the second impeller chamber 33 accommodates the second impeller 43. The second impeller 43 compresses the air sucked into the second impeller chamber 33 by rotating integrally with the rotating shaft 41. Therefore, the second impeller 43 is an impeller that compresses air. Therefore, the second impeller chamber 33 is an impeller chamber that accommodates an impeller. Therefore, the housing 11 has an impeller chamber that accommodates the impeller. The second impeller 43 compresses the air compressed by the first impeller 42.

The support portion 44 protrudes in an annular shape from the outer peripheral surface of the rotating shaft 41. The support portion 44 has a disk shape. The support portion 44 is fixed to the outer circumferential surface of the rotating shaft 41 in a state in which it annularly protrudes radially outward from the outer circumferential surface of the rotating shaft 41 . Therefore, the support portion 44 is separate from the rotating shaft 41. The support portion 44 is arranged within the thrust bearing housing chamber 24 . The support portion 44 rotates integrally with the rotating shaft 41.

The centrifugal compressor 10 includes a first seal member 45. The first seal member 45 is provided between the first insertion hole 23 and the rotating shaft 41. The first seal member 45 suppresses air leakage from the first impeller chamber 28 toward the motor chamber 18 . The first seal member 45 is, for example, a seal ring.

The centrifugal compressor 10 includes a second seal member 46. The second seal member 46 is provided between the second insertion hole 26 and the rotating shaft 41. The second seal member 46 suppresses air leakage from the second impeller chamber 33 toward the motor chamber 18 . The second seal member 46 is, for example, a seal ring.

The motor 20 includes a cylindrical rotor 47 and a cylindrical stator 48. The rotor 47 is fixed to the rotating shaft 41. Stator 48 is fixed to housing 11. The rotor 47 is arranged radially inside the stator 48. The rotor 47 rotates integrally with the rotating shaft 41. The rotor 47 includes a cylindrical rotor core 49 fixed to the rotating shaft 41 and a plurality of permanent magnets (not shown) provided in the rotor core 49. Stator 48 surrounds rotor 47. The stator 48 has a cylindrical stator core 50 and a coil 51. Stator core 50 is fixed to the inner peripheral surface of motor housing 12. Coil 51 is wound around stator core 50 .

The rotating shaft 41 rotates integrally with the rotor 47 when current flows through the coil 51 from a battery (not shown). Therefore, the motor 20 rotates the rotating body 40. The motor 20 is arranged between the first impeller 42 and the second impeller 43 in the axial direction of the rotating shaft 41.

The centrifugal compressor 10 includes a first radial bearing 52. The first radial bearing 52 has a cylindrical shape. The first radial bearing 52 is held by the first bearing holding part 21. The first radial bearing 52 rotatably supports a portion of the rotating shaft 41 that is located closer to the first end of the rotating shaft 41 than the motor 20 is.

The centrifugal compressor 10 includes a second radial bearing 53. The second radial bearing 53 has a cylindrical shape. The second radial bearing 53 is held by the second bearing holding part 25. The second radial bearing 53 rotatably supports a portion of the rotating shaft 41 that is located closer to the second end of the rotating shaft 41 than the motor 20 is.

The first radial bearing 52 and the second radial bearing 53 rotatably support the rotating shaft 41 in the radial direction at positions on both sides of the motor 20 in the axial direction of the rotating shaft 41. Note that the "radial direction" is a direction perpendicular to the axial direction of the rotating shaft 41.

The centrifugal compressor 10 includes a thrust bearing 54. The thrust bearing 54 is housed in the thrust bearing housing chamber 24. Therefore, the thrust bearing accommodation chamber 24 accommodates the thrust bearing 54. The thrust bearing 54 rotatably supports the support portion 44 in the thrust direction. Therefore, the thrust bearing 54 rotatably supports the rotating shaft 41 via the support portion 44. Note that the "thrust direction" is a direction parallel to the axial direction of the rotating shaft 41.

The air sucked into the first impeller chamber 28 through the first intake port 27 is accelerated by the rotation of the first impeller 42 and is sent into the first diffuser flow path 30 and passes through the first diffuser flow path 30. The pressure is increased by The air that has passed through the first diffuser flow path 30 is then discharged into the first discharge chamber 29. The air discharged into the first discharge chamber 29 is discharged into the first discharge passage 31 . The air discharged into the first discharge passage 31 is sucked into the second impeller chamber 33 via the connecting pipe 39 and the second suction port 32 . The air sucked into the second impeller chamber 33 is accelerated by the rotation of the second impeller 43, and is sent into the second diffuser flow path 35, and is increased in pressure by passing through the second diffuser flow path 35. The air that has passed through the second diffuser flow path 35 is then discharged into the second discharge chamber 34. The air discharged into the second discharge chamber 34 is discharged into the second discharge passage 36. The air discharged into the second discharge passage 36 is supplied to the fuel cell stack 38 via the supply pipe 37. Therefore, centrifugal compressor 10 supplies air to fuel cell stack 38 . Oxygen contained in the air supplied to the fuel cell stack 38 contributes to power generation by the fuel cell stack 38.

The rotating body 40 includes a first impeller 42 and a second impeller 43 that compress air supplied to the fuel cell stack 38. Therefore, the rotating body 40 includes an impeller. The second discharge passage 36 and the supply pipe 37 constitute a supply passage 55 that supplies air to the fuel cell stack 38. The second discharge chamber 34 is a discharge chamber to which air compressed by the second impeller 43 is discharged and to which the supply flow path 55 is connected. Therefore, the housing 11 has a discharge chamber to which the supply channel 55 is connected.

The centrifugal compressor 10 includes an introduction passage 56. The introduction passage 56 is formed in the first plate 15. A first end of the introduction passage 56 is open to the outer circumferential surface of the first plate 15 . A second end of the introduction passage 56 communicates with the thrust bearing housing chamber 24 .

A branch pipe 57 is connected to the first end of the introduction passage 56. The branch pipe 57 is branched from the middle of the supply pipe 37. A first end of the branch pipe 57 is connected to the supply pipe 37. A second end of the branch pipe 57 is connected to a first end of the introduction passage 56. An intercooler 58 is provided in the middle of the branch pipe 57. The intercooler 58 cools the air flowing inside the branch pipe 57.

A part of the air flowing through the supply pipe 37 flows into the branch pipe 57. Air flowing through branch pipe 57 is cooled by intercooler 58 . Thereby, the temperature of the air that has passed through the intercooler 58 is lower than the temperature of the air discharged into the second discharge chamber 34. The air cooled by the intercooler 58 passes through the introduction passage 56, the thrust bearing housing chamber 24, and the first bearing holding portion 21, and is introduced into the motor chamber 18. Therefore, the introduction passage 56 introduces a portion of the air compressed by the second impeller 43 into the motor chamber 18 at a temperature lower than the temperature of the air discharged into the second discharge chamber 34 .

The centrifugal compressor 10 is equipped with a discharge passage 59. The discharge passage 59 is formed in the second plate 16. A first end of the discharge passage 59 communicates with a portion of the second insertion hole 26 closer to the motor chamber 18 than the second seal member 46 . The second end of the discharge passage 59 is open to the outer circumferential surface of the second plate 16 . Therefore, the discharge path 59 communicates with the outside of the housing 11. The air that has flowed from inside the motor chamber 18 through the inside of the second bearing holding part 25 and into the second insertion hole 26 is discharged to the outside of the housing 11 via the discharge passage 59.

As shown in FIG. 2, the second impeller 43 is cylindrical and its diameter gradually decreases from the back surface 43a to the tip. The back surface 43a of the second impeller 43 faces the second plate 16. Therefore, the second plate 16 has an opposing surface 16a that faces the back surface 43a of the second impeller 43. The second impeller 43 has a through hole 43h. The axis of the through hole 43h coincides with the rotation axis of the second impeller 43. The rotation axis of the second impeller 43 is also the rotation axis of the rotor 40.

The second impeller 43 has a cylindrical boss portion 60. The boss portion 60 protrudes from the center of the back surface 43a of the second impeller 43. The inside of the boss portion 60 communicates with the through hole 43h. The rotating shaft 41 passes through the inside of the boss portion 60 and the through hole 43h. The boss portion 60 enters the second insertion hole 26. Therefore, the boss portion 60 is located inside the second insertion hole 26. The boss portion 60 is a portion of the rotating body 40 located inside the second insertion hole 26 .

<Aperture section 61, communication section 62, discharge passage 63>
The centrifugal compressor 10 includes a throttle section 61, a communication section 62, and a discharge passage 63. The outer circumferential surface of the boss portion 60 has a first outer circumferential surface 64 , a second outer circumferential surface 65 , and a first stepped surface 66 . The first outer circumferential surface 64 is continuous with the back surface 43a of the second impeller 43. The first outer circumferential surface 64 extends in the direction of the rotational axis of the rotating body 40 .

The second outer circumferential surface 65 is located further away from the back surface 43a of the second impeller 43 than the first outer circumferential surface 64. The second outer circumferential surface 65 is located closer to the motor chamber 18 than the first outer circumferential surface 64 . The second outer circumferential surface 65 extends in the direction of the rotational axis of the rotating body 40 . The second outer peripheral surface 65 has a smaller outer diameter than the first outer peripheral surface 64.

The first stepped surface 66 connects the first outer circumferential surface 64 and the second outer circumferential surface 65. The first step surface 66 extends in a direction perpendicular to the direction of the rotational axis of the rotating body 40 . Therefore, the first stepped surface 66 extends in a direction intersecting the direction of the rotational axis of the rotating body 40. The first stepped surface 66 is annular.

The inner circumferential surface of the second insertion hole 26 has a first inner circumferential surface 67 , a second inner circumferential surface 68 , and a second step surface 69 . The first inner circumferential surface 67 is continuous with the opposing surface 16a. The first inner peripheral surface 67 extends along the first outer peripheral surface 64.

The second inner circumferential surface 68 is located further away from the opposing surface 16a than the first inner circumferential surface 67. The second inner circumferential surface 68 is located closer to the motor chamber 18 than the first inner circumferential surface 67 is. The second inner peripheral surface 68 extends along the second outer peripheral surface 65. The second inner peripheral surface 68 has a smaller inner diameter than the first inner peripheral surface 67.

The second stepped surface 69 connects the first inner circumferential surface 67 and the second inner circumferential surface 68. The second step surface 69 extends in a direction perpendicular to the direction of the rotational axis of the rotating body 40 . Therefore, the second step surface 69 extends in a direction intersecting the direction of the rotational axis of the rotating body 40. The second step surface 69 is annular. The second step surface 69 extends along the first step surface 66.

The constricted portion 61 is a gap between the first outer circumferential surface 64 and the first inner circumferential surface 67. Therefore, the constricted portion 61 is formed between the second insertion hole 26 and the rotating body 40. The constricting portion 61 constricts the air flowing into the second insertion hole 26 from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16. The throttle portion 61 makes the pressure of the air flowing into the second insertion hole 26 from the gap 70 lower than the pressure inside the motor chamber 18 . Therefore, the flow path in the gap between the first outer circumferential surface 64 and the second inner circumferential surface 68 is cut off so that the pressure of the air flowing into the second insertion hole 26 from the gap 70 is lower than the pressure inside the motor chamber 18. The area is set.

The second insertion hole 26 has a seal receiving hole 71. A first end of the seal housing hole 71 communicates with a gap between the second outer circumferential surface 65 and the second inner circumferential surface 68 . The second end of the seal housing hole 71 communicates with the inside of the second bearing holding portion 25 . The gap between the second outer circumferential surface 65 and the second inner circumferential surface 68 communicates with the motor chamber 18 via the seal housing hole 71 and the inside of the second bearing holding portion 25 .

The communication portion 62 is formed by a gap between the first step surface 66 and the second step surface 69 and a gap between the second outer circumferential surface 65 and the second inner circumferential surface 68. Therefore, the communication portion 62 is formed between the second insertion hole 26 and the rotating body 40. The communication portion 62 includes a gap between the first step surface 66 and the second step surface 69 and a gap between the second outer circumferential surface 65 and the second inner circumferential surface 68.

The gap between the first step surface 66 and the second step surface 69 extends in a direction perpendicular to the direction in which the gap between the first outer circumferential surface 64 and the first inner circumferential surface 67 extends. Therefore, the communication portion 62 extends in a direction perpendicular to the flow direction of the air that has passed through the throttle portion 61 and then communicates with the motor chamber 18 . Therefore, the communication portion 62 extends in a direction perpendicular to the flow direction of the air that has passed through the constriction portion 61 and then communicates with the motor chamber 18 .

The discharge passage 63 is formed in the second plate 16. The discharge passage 63 penetrates the inside of the second plate 16. The discharge passage 63 has an axial passage 63a, a radial passage 63b, and a connection passage 63c. The axial passage 63a extends in the direction of the rotation axis of the rotating body 40. The axial passage 63a communicates with the throttling portion 61 and the communication portion 62. The axial passage 63a is connected to the connection point between the throttling portion 61 and the communication portion 62. The radial passage 63b extends in a direction perpendicular to the direction of the rotation axis of the rotating body 40. The radial passage 63b penetrates the inside of the second plate 16 and opens on the outer circumferential surface of the second plate 16. The connection passage 63c connects the axial passage 63a and the radial passage 63b. As the connection passage 63c moves away from the axial passage 63a, it extends in a direction away from the rotation axis of the rotating body 40 and is connected to the radial passage 63b.

The axial path 63a forms a first end of the discharge passage 63. Therefore, the first end of the discharge passage 63 communicates with the throttle section 61 and the communication section 62. The end of the path 63b opposite to the connection path 63c forms a second end of the discharge passage 63. Therefore, the second end of the discharge passage 63 communicates with the outside of the housing 11.

The first end of the discharge passage 63 is the end of the discharge passage 63 on the side opposite to the outside of the housing 11. The first end of the discharge passage 63 faces the gap between the first outer circumferential surface 64 and the first inner circumferential surface 67 in the direction of the rotational axis of the rotating body 40 . Therefore, the axial path 63a of the discharge passage 63 extends in the flow direction of the air that has passed through the throttle section 61.

The cross-sectional area of the passage 63b gradually increases as it moves away from the connection passage 63c. The air flowing through the path 63b is decelerated while passing through the path 63b, thereby increasing its pressure. Therefore, the path 63b discharges the air to the outside of the housing 11 while increasing the pressure of the air that has passed through the constriction part 61 and has become lower than the pressure inside the motor chamber 18. In this way, the discharge passage 63 extends in the flow direction of the air that has passed through the constriction part 61 and discharges the air that has passed through the constriction part 61 to the outside of the housing 11 while increasing the pressure of the air.

[Operation of embodiment]
Next, the operation of this embodiment will be explained.
The thrust bearing 54 is cooled by air introduced into the thrust bearing housing chamber 24 from the introduction passage 56. The air within the thrust bearing housing chamber 24 passes through the inside of the first bearing holding portion 21 . The first radial bearing 52 is cooled by air passing inside the first bearing holding part 21 . The air that has passed inside the first bearing holding part 21 is introduced into the motor chamber 18. Motor 20 is cooled by air introduced into motor chamber 18 . Therefore, in the centrifugal compressor 10, a part of the air compressed by the second impeller 43 is introduced into the motor chamber 18 at a temperature lower than the temperature of the air discharged into the second discharge chamber 34. As a result, the motor 20 is cooled down. The air introduced into the motor chamber 18 passes inside the second bearing holding section 25 . The second radial bearing 53 is cooled by air passing inside the second bearing holding section 25 . The air that has passed through the inside of the second bearing holding part 25 is discharged to the outside of the housing 11 via the discharge path 59.

Incidentally, a part of the air compressed by the second impeller 43 and discharged into the second discharge chamber 34 may flow into the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16. The air that has flowed into the gap 70 then flows into the second insertion hole 26 from the gap 70 . At this time, the speed of the air flowing into the second insertion hole 26 from the gap 70 increases as it passes through the constriction part 61. Thereby, the pressure of the air after passing through the constriction part 61 becomes lower than the pressure of the air before passing through the constriction part 61. Specifically, the throttle portion 61 makes the pressure of the air flowing from the gap 70 into the second insertion hole 26 lower than the pressure inside the motor chamber 18 .

The communication portion 62 extends in a direction intersecting the flow direction of the air that has passed through the constriction portion 61. Therefore, the air that has passed through the throttle section 61 is less likely to flow into the motor chamber 18 via the communication section 62. The discharge passage 63 extends in the flow direction of the air that has passed through the constriction section 61. Therefore, the air that has passed through the constriction section 61 easily flows into the discharge passage 63. Therefore, the air flowing into the second insertion hole 26 from the gap 70 is easily discharged to the outside of the housing 11 through the discharge passage 63 while increasing the pressure. As a result, a portion of the air compressed by the second impeller 43 and discharged into the second discharge chamber 34 is prevented from entering the motor chamber 18 through the second insertion hole 26.

[Effects of the embodiment]
The above embodiment can provide the following effects.
(1) The speed of the air flowing from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16 into the second insertion hole 26 increases by passing through the throttle portion 61. As a result, the pressure of the air after passing through the throttle portion 61 becomes lower than the pressure of the air before passing through the throttle portion 61. The communication portion 62 extends in a direction intersecting the flow direction of the air that has passed through the throttle portion 61. Therefore, it is difficult for the air that has passed through the throttle portion 61 to flow into the motor chamber 18 through the communication portion 62. The exhaust passage 63 extends in the flow direction of the air that has passed through the throttle portion 61. Therefore, it is easy for the air that has passed through the throttle portion 61 to flow into the exhaust passage 63. Therefore, the air that flows from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16 into the second insertion hole 26 is easily discharged to the outside of the housing 11 through the exhaust passage 63 while increasing in pressure. As a result, a part of the air compressed by the second impeller 43 and discharged to the second discharge chamber 34 is prevented from entering the motor chamber 18 through the second insertion hole 26. Therefore, a problem that the motor 20 is warmed by the air that has entered the motor chamber 18 due to a part of the air compressed by the second impeller 43 and discharged to the second discharge chamber 34 entering the motor chamber 18 through the second insertion hole 26 is unlikely to occur. Therefore, by introducing a part of the air compressed by the second impeller 43 into the motor chamber 18 at a temperature lower than the temperature of the air discharged to the second discharge chamber 34, the motor 20 can be efficiently cooled. As a result, the durability of the centrifugal compressor 10 can be improved.

(2) The constricted portion 61 is a gap between the first outer circumferential surface 64 and the first inner circumferential surface 67. The communication portion 62 includes a gap between the first step surface 66 and the second step surface 69 and a gap between the second outer circumferential surface 65 and the second inner circumferential surface 68. The end of the discharge passage 63 on the side opposite to the outside of the housing 11 faces the gap between the first outer circumferential surface 64 and the first inner circumferential surface 67 in the direction of the rotational axis of the rotating body 40 . Such a configuration includes a constricted portion 61 formed between the second insertion hole 26 and the rotating body 40, a communication portion 62 formed between the second insertion hole 26 and the rotating body 40, and a second This is a suitable configuration for the centrifugal compressor 10 that includes a discharge passage 63 formed in the plate 16.

(3) The throttle part 61 makes the pressure of the air flowing into the second insertion hole 26 from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16 lower than the pressure inside the motor chamber 18. Therefore, it is easier to prevent part of the air compressed by the second impeller 43 and discharged into the second discharge chamber 34 from entering the motor chamber 18 through the second insertion hole 26. be able to.

[Example of change]
Note that the above embodiment can be modified and implemented as follows. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

As shown in FIG. 3, the outer diameter of the outer peripheral surface of the boss portion 60 may be constant. The rotating body 40 includes a cylindrical member 80. The cylindrical member 80 is fixed to the outer peripheral surface of the rotating shaft 41. The cylindrical member 80 rotates integrally with the rotating shaft 41. The outer peripheral surface of the cylindrical member 80 is located radially outward of the rotating shaft 41 relative to the outer peripheral surface of the boss portion 60. The end face of the boss portion 60 opposite the back surface 43a of the second impeller 43 abuts against the end face 80a of the cylindrical member 80.

The inner circumferential surface of the second insertion hole 26 has a third inner circumferential surface 81 , a fourth inner circumferential surface 82 , and a third stepped surface 83 . The third inner circumferential surface 81 is continuous with the opposing surface 16a. The third inner circumferential surface 81 extends along the outer circumferential surface of the boss portion 60. The fourth inner circumferential surface 82 is located further away from the opposing surface 16a than the third inner circumferential surface 81 is. The fourth inner circumferential surface 82 is located closer to the motor chamber 18 than the third inner circumferential surface 81 is. The fourth inner peripheral surface 82 extends along the outer peripheral surface of the cylindrical member 80. The fourth inner peripheral surface 82 has a larger inner diameter than the third inner peripheral surface 81. The third stepped surface 83 connects the third inner circumferential surface 81 and the fourth inner circumferential surface 82 . The third step surface 83 extends in a direction perpendicular to the direction of the rotational axis of the rotating body 40 . The third step surface 83 extends along the end surface 80a of the cylindrical member 80.

The centrifugal compressor 10 includes a throttle section 84, a communication section 85, and a discharge passage 86. The throttle portion 84 is formed by a gap between the outer circumferential surface of the boss portion 60 and the third inner circumferential surface 81 and a gap between the third step surface 83 and the end surface 80 a of the cylindrical member 80 . Therefore, the constricted portion 84 is formed between the second insertion hole 26 and the rotating body 40. The constricting portion 84 constricts the air flowing into the second insertion hole 26 from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16. The throttle portion 84 makes the pressure of the air flowing into the second insertion hole 26 from the gap 70 lower than the pressure inside the motor chamber 18 . Therefore, the gap between the outer circumferential surface of the boss portion 60 and the third inner circumferential surface 81 and the The flow passage cross-sectional area of the gap between the three-step surface 83 and the end surface 80a of the cylindrical member 80 is set.

The communication portion 85 is a gap between the outer peripheral surface of the cylindrical member 80 and the fourth inner peripheral surface 82. Therefore, the communication portion 85 is formed between the second insertion hole 26 and the rotating body 40. A gap between the outer circumferential surface of the cylindrical member 80 and the fourth inner circumferential surface 82 communicates with the seal accommodation hole 71 . The gap between the outer circumferential surface of the cylindrical member 80 and the fourth inner circumferential surface 82 extends in a direction perpendicular to the direction in which the gap between the third step surface 83 and the end surface 80a of the cylindrical member 80 extends. ing. Therefore, the communication portion 85 extends in a direction perpendicular to the flow direction of the air that has passed through the throttle portion 84 and then communicates with the motor chamber 18 . Therefore, the communication portion 85 extends in a direction perpendicular to the flow direction of the air that has passed through the constriction portion 84 and then communicates with the motor chamber 18 .

A discharge passage 86 is formed in the second plate 16. The discharge passage 86 penetrates inside the second plate 16. The discharge passage 86 extends in a direction perpendicular to the direction of the rotational axis of the rotating body 40 . A first end of the discharge passage 86 communicates with the constriction portion 84 and the communication portion 85 . A first end of the discharge passage 86 is connected to a connection point between the throttle section 84 and the communication section 85. The second end of the discharge passage 86 is open to the outer circumferential surface of the second plate 16. The discharge passage 86 faces the gap between the third step surface 83 and the end surface 80a of the cylindrical member 80 in the radial direction of the rotating shaft 41. Therefore, the discharge passage 86 extends in the flow direction of the air that has passed through the constriction section 84.

The cross-sectional area of the discharge passage 86 gradually increases as the distance from the constriction part 84 increases. The air flowing through the exhaust passage 86 is decelerated as it passes through the exhaust passage 86, thereby increasing its pressure. Therefore, the discharge passage 86 discharges the air to the outside of the housing 11 while increasing the pressure of the air that has passed through the constriction portion 84 and has become lower than the pressure inside the motor chamber 18 . In this way, the discharge passage 86 extends in the flow direction of the air that has passed through the constriction part 84 and discharges the air that has passed through the constriction part 84 to the outside of the housing 11 while increasing the pressure of the air. Such a configuration includes a constricted portion 84 formed between the second insertion hole 26 and the rotating body 40, a communication portion 85 formed between the second insertion hole 26 and the rotating body 40, and a second A discharge passage 86 formed in the plate 16 is suitable as a configuration of the centrifugal compressor 10.

In the embodiment, the throttle part 61 makes the pressure of the air flowing into the second insertion hole 26 from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16 lower than the pressure inside the motor chamber 18. It does not have to be configured as . In short, the restricting portion 61 may have any configuration as long as it restricts the air flowing into the second insertion hole 26 from the gap 70 between the back surface 43a of the second impeller 43 and the second plate 16. The pressure of the air after passing through the constriction part 61 only needs to be lower than the pressure of the air before passing through the constriction part 61. According to this, the air that has passed through the throttle section 61 becomes difficult to flow into the motor chamber 18 via the communication section 62.

In the embodiment, the first step surface 66 may extend obliquely with respect to the rotational axis direction of the rotating body 40. The second step surface 69 may extend along the first step surface 66 obliquely with respect to the rotational axis direction of the rotating body 40. Therefore, the gap between the first stepped surface 66 and the second stepped surface 69 may extend obliquely to the direction in which the gap between the first outer circumferential surface 64 and the first inner circumferential surface 67 extends. . In short, the communication section 62 only needs to extend in a direction intersecting the flow direction of the air that has passed through the throttle section 61 and then communicate with the motor chamber 18 .

In the embodiment, the introduction passage 56 may introduce a portion of the air compressed by the first impeller 42 into the motor chamber 18. The temperature of the air compressed by the first impeller 42 is lower than the temperature of the air compressed by the second impeller 43 and discharged into the second discharge chamber 34 . In short, the introduction passage 56 only needs to introduce air into the motor chamber 18 at a temperature lower than the temperature of the air discharged into the second discharge chamber 34 .

In the embodiment, the centrifugal compressor 10 may be configured without the second impeller 43. In this case, the throttle part 61 throttles the air flowing into the first insertion hole 23 from the gap between the back surface of the first impeller 42 and the third plate 17 . Moreover, the discharge passage 63 penetrates inside the third plate 17 .

In the embodiment, the centrifugal compressor 10 may be configured to include a turbine wheel instead of the second impeller 43.
In the embodiment, the centrifugal compressor 10 does not need to be mounted on the fuel cell vehicle. In short, the centrifugal compressor 10 is not limited to one that is mounted on a vehicle.

10 Centrifugal compressor 11 Housing 15 First plate (partition wall)
16 Second plate (partition wall)
17 Third plate (partition wall)
18 Motor chamber 20 Motor 23 First insertion hole (insertion hole)
26 Second insertion hole (insertion hole)
28 1st impeller room (impeller room)
33 Second impeller room (impeller room)
34 Second discharge chamber which is a discharge chamber 38 Fuel cell stack 40 Rotating body 42 First impeller (impeller)
43 Second impeller (impeller)
43a Rear surface 55

Supply channel

61, 84

Restricted portion

62, 85

Communication portion

63, 86 Discharge passage 64 First outer circumferential surface 65 Second outer circumferential surface 66 First step surface 67 First inner circumferential surface 68 Second inner circumferential surface 69 2-step surface 70 air gap

Claims

a rotating body including an impeller that compresses air supplied to the fuel cell stack;
a motor that rotates the rotating body;
an impeller chamber that accommodates the impeller; a motor chamber that accommodates the motor; a partition wall that partitions the impeller chamber and the motor chamber and is formed with an insertion hole through which the rotating body is inserted; a housing having a discharge chamber through which air is discharged and to which a supply flow path for supplying the air to the fuel cell stack is connected;
A centrifugal compressor that cools the motor by introducing a part of the air compressed by the impeller into the motor chamber at a temperature lower than the temperature of the air discharged into the discharge chamber,
a constriction portion that is formed between the insertion hole and the rotating body and that throttles air flowing into the insertion hole from a gap between the back surface of the impeller and the partition wall;
a communication portion formed between the insertion hole and the rotating body and extending in a direction intersecting the flow direction of the air that has passed through the constriction portion, and communicating with the motor chamber;
A discharge passage is formed in the partition wall and extends in the flow direction of the air that has passed through the constriction part, and discharges the air that has passed through the constriction part to the outside of the housing while increasing the pressure of the air. centrifugal compressor.
The outer circumferential surface of the portion of the rotating body located inside the insertion hole is
a first outer peripheral surface;
a second outer circumferential surface that is located closer to the motor chamber than the first outer circumferential surface and has a smaller outer diameter than the first outer circumferential surface;
a first stepped surface connecting the first outer circumferential surface and the second outer circumferential surface and extending in a direction intersecting the rotational axis direction of the rotating body;
The inner peripheral surface of the insertion hole is
a first inner circumferential surface extending along the first outer circumferential surface;
a second inner circumferential surface extending along the second outer circumferential surface and having an inner diameter smaller than the first inner circumferential surface;
a second step surface connecting the first inner circumferential surface and the second inner circumferential surface and extending along the first step surface;
The narrowed portion is a gap between the first outer circumferential surface and the first inner circumferential surface,
The communication portion includes a gap between the first step surface and the second step surface, and a gap between the second outer circumferential surface and the second inner circumferential surface,
An end of the discharge passage opposite to the outside of the housing faces a gap between the first outer circumferential surface and the first inner circumferential surface in the direction of the rotation axis. The centrifugal compressor according to claim 1.
The centrifugal compressor according to claim 1 or 2, wherein the throttle section makes the pressure of the air flowing from the gap into the insertion hole lower than the pressure inside the motor chamber.