CENTRIFUGAL COMPRESSOR

Abstract

A centrifugal compressor that includes: a rotary shaft; a compressor impeller mounted on the rotary shaft and configured to rotate together with the rotary shaft to compress a fluid; a housing accommodating the rotary shaft and the compressor impeller; and a thrust bearing supporting the rotary shaft in a thrust direction such that the rotary shaft is rotatable. The housing includes: an impeller chamber in which the compressor impeller is accommodated; a thrust bearing accommodation chamber in which the thrust bearing is accommodated; and a partition wall separating the impeller chamber from the thrust bearing accommodation chamber. The partition wall has therein a cooling gas passage through which cooling gas flows to cool the thrust bearing and a cooling water passage through which cooling water flows to cool the partition wall.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2021-188834 filed on Nov. 19, 2021, the entire disclosure of which is incorporated herein by reference.

The present disclosure relates to a centrifugal compressor.

BACKGROUND ART

A known centrifugal compressor is mentioned, for example, in Japanese Patent Application Publication No. 2019-127898. The centrifugal compressor includes a rotary shaft and a compressor impeller. The compressor impeller is mounted on the rotary shaft. The compressor impeller is rotated together with the rotary shaft. The compressor impeller is configured to compress a fluid. The centrifugal compressor includes a housing for accommodating the rotary shaft and the compressor impeller. The centrifugal compressor further includes a thrust bearing. The thrust bearing supports the rotary shaft in a thrust direction such that the rotary shaft is rotatable.

The housing has an impeller chamber and a thrust bearing accommodation chamber. The impeller chamber accommodates the compressor impeller. The thrust bearing accommodation chamber accommodates the thrust bearing. The housing has a partition wall that separates the impeller chamber from the thrust bearing accommodation chamber.

The temperature of the fluid is increased by compression by the compressor impeller. If the heat of the compressed fluid transfers to the thrust bearing accommodated in the thrust bearing accommodation chamber via the partition wall, the heat of the fluid increases the temperature of the thrust bearing, thereby decreasing the durability of the thrust bearing. It is therefore necessary to increase the ability of the centrifugal compressor to cool the thrust bearing.

SUMMARY

In accordance with an aspect of the present disclosure, there is provided a centrifugal compressor that includes: a rotary shaft; a compressor impeller mounted on the rotary shaft and configured to rotate together with the rotary shaft to compress a fluid; a housing accommodating the rotary shaft and the compressor impeller; and a thrust bearing supporting the rotary shaft in a thrust direction such that the rotary shaft is rotatable. The housing includes: an impeller chamber in which the compressor impeller is accommodated; a thrust bearing accommodation chamber in which the thrust bearing is accommodated; and a partition wall separating the impeller chamber from the thrust bearing accommodation chamber. The partition wall has therein a cooling gas passage through which cooling gas flows to cool the thrust bearing and a cooling water passage through which cooling water flows to cool the partition wall.

Other aspects and advantages of the disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a sectional side view of a centrifugal compressor according to an embodiment of the present disclosure;

FIG. 2 is a fragmentary enlarged sectional side view of the centrifugal compressor according to the embodiment; and

FIG. 3 is a front view of a seal plate.

DESCRIPTION OF EMBODIMENTS

The following will describe an embodiment of a centrifugal compressor with reference to accompanying FIGS. 1 to 3. The centrifugal compressor according to the embodiment is mounted on a fuel cell vehicle.

<Configuration of Centrifugal Compressor 10>

As illustrated in FIG. 1, a centrifugal compressor 10 includes a housing 11. The housing 11 is made of metal, such as aluminum. The housing 11 includes a motor housing 12, a compressor housing 13, a turbine housing 14, a first plate 15, a second plate 16, and a seal plate 17.

The motor housing 12 has a cylindrical shape. The motor housing 12 includes a plate-like end wall 12a and a peripheral wall 12b. The peripheral wall 12b has a cylindrical shape and protrudes from an outer peripheral portion of the end wall 12a. The first plate 15 is connected to an open end of the peripheral wall 12b of the motor housing 12 so as to close the opening of the peripheral wall 12b. The end wall 12a and the peripheral wall 12b of the motor housing 12 cooperate with the first plate 15 to define a motor chamber S1. The motor chamber S1 accommodates an electric motor 40.

As illustrated in FIG. 2, an end face 15a of the first plate 15 that is distant from the motor housing 12 has a first recess 15c and a second recess 15d. The first recess 15c and the second recess 15d each have a circular hole shape. The inner diameter of the first recess 15c is greater than that of the second recess 15d. The first recess 15c is formed coaxially with the second recess 15d. The first recess 15c has an inner peripheral surface 15e through which the end face 15a is connected to a bottom surface 15f of the first recess 15c. The second recess 15d has an inner peripheral surface 15g through which the bottom surface 15f of the first recess 15c is connected to a bottom surface 15h of the second recess 15d.

The first plate 15 has a first bearing holding portion 20. The first bearing holding portion 20 has a cylindrical shape. The first bearing holding portion 20 projects from the center portion of an end face 15b of the first plate 15 toward the electric motor 40. On the opposite side, the first bearing holding portion 20 is formed through the first plate 15 to open on the bottom surface 15h of the second recess 15d. The first bearing holding portion 20 is formed coaxially with the first recess 15c and the second recess 15d.

As illustrated in FIG. 1, the motor housing 12 has a second bearing holding portion 21. The second bearing holding portion 21 has a cylindrical shape. The second bearing holding portion 21 projects from the center portion of an inner surface 121a of the end wall 12a of the motor housing 12 toward the electric motor 40. The cylindrical second bearing holding portion 21 is formed through the end wall 12a of the motor housing 12 to open on an outer surface 122a of the end wall 12a. The first beating holding portion 20 is formed coaxially with the second bearing holding portion 21.

The second plate 16 is connected to the outer surface 122a of the end wall 12a of the motor housing 12. The second plate 16 has a shaft insertion hole 16a at the center portion of the second plate 16. The shaft insertion hole 16a is communicated with the second bearing holding portion 21. The shaft insertion hole 16a is formed coaxially with the second bearing holding portion 21.

As illustrated in FIG. 2, the seal plate 17 has a shaft insertion hole 17a at the center portion of the seal plate 17. The shaft insertion hole 17a is formed coaxially with the first bearing holding portion 20. The seal plate 17 has a plurality of bolt insertion holes 17h through which a plurality of bolts B1 is inserted. The bolt insertion holes 17h are formed in an outer peripheral portion of the seal plate 17 and spaced apart from each other around the shaft insertion hole 17a. FIG. 2 illustrates only one of the bolt insertion holes 17h. Each of the bolt insertion holes 17h has a circular hole shape. The seal plate 17 is fitted in the first recess 15c and fixed to the first plate 15 by the bolts B1 inserted through the bolt insertion holes 17h. The seal plate 17 closes the opening of the second recess 15d. The seal plate 17 has an end face 17b that is adjacent to the first plate 15 and cooperates with the second recess 15d of the first plate 15 to define a thrust bearing accommodation chamber S2.

The compressor housing 13 has a cylindrical shape. The compressor housing 13 has an inlet 13a that has a circular hole shape. The compressor housing 13 is connected to the end face 15a of the first plate 15 with the axis of the inlet 13a coaxial with the axis of the shaft insertion hole 17a of the seal plate 17 and the axis of the first bearing holding portion 20. The inlet 13a is opened on an end face of the compressor housing 13 that is distant from the first plate 15.

An impeller chamber 13b, a discharge chamber 13c, and a first diffuser passage 13d are formed between the compressor housing 13 and the seal plate 17. Accordingly, the seal plate 17 serves as a partition wall that separates the impeller chamber 13b from the thrust bearing accommodation chamber S2. The impeller chamber 13b is communicated with the inlet 13a. The discharge chamber 13c extends about the axis of the inlet 13a around the impeller chamber 13b. The impeller chamber 13b is communicated with the discharge chamber 13c through the first diffuser passage 13d. The impeller chamber 13b is communicated with the shaft insertion hole 17a of the seal plate 17.

As illustrated in FIG. 1, the turbine housing 14 has a cylindrical shape. The turbine housing 14 has an outlet 14a that has a circular hole shape. The turbine housing 14 is connected to an end face 16b of the second plate 16 that is distant from the motor housing 12 with the axis of the outlet 14a coaxial with the axis of the shaft insertion hole 16a of the second plate 16 and the axis of the second bearing holding portion 21. The outlet 14a is opened on an end face of the turbine housing 14 that is distant from the second plate 16.

A turbine chamber 14b, a suction chamber 14c, and a second diffuser passage 14d are formed between the turbine housing 14 and the end face 16b of the second plate 16. The turbine chamber 14b is communicated with the outlet 14a. The suction chamber 14c extends about the axis of the outlet 14a around the turbine chamber 14b. The turbine chamber 14b is communicated with the suction chamber 14c through the second diffuser passage 14d. The turbine chamber 14b is communicated with the shaft insertion hole 16a.

<Configuration of Rotating Member A1>

The centrifugal compressor 10 includes a rotating member A1. The rotating member A1 includes a rotary shaft 30, a first supporting portion 31, a second supporting portion 32, and a support plate 33. That is, the centrifugal compressor 10 includes the rotary shaft 30. The rotary shaft 30, the first supporting portion 31, the second supporting portion 32, and the support plate 33 are accommodated in the housing 11.

The axis of the rotary shaft 30 accommodated in the housing 11 is coaxial with the axis of the motor housing 12. The rotary shaft 30 has a first end portion 30a, and the rotary shaft 30 extends through the motor chamber S1, the first bearing holding portion 20, the thrust bearing accommodation chamber S2, and the shaft insertion hole 17a so that the first end portion 30a protrudes into the impeller chamber 13b. The rotary shaft 30 has a second end portion 30b, and the rotary shaft 30 extends through the motor chamber S1, the second bearing holding portion 21, and the shaft insertion hole 16a so that the second end portion 30b protrudes into the turbine chamber 14b.

A first sealing member 22 is disposed between the shaft insertion hole 17a of the seal plate 17 and the rotary shaft 30. The first sealing member 22 suppresses leak of air from the impeller chamber 13b toward the motor chamber S1. A second sealing member 23 is disposed between the shaft insertion hole 16a of the second plate 16 and the rotary shaft 30. The second sealing member 23 suppresses leak of air from the turbine chamber 14b toward the motor chamber S1. The first sealing member 22 and the second sealing member 23 are each a seal ring, for example.

The first supporting portion 31 is formed in a part of an outer peripheral surface 300 of the rotary shaft 30 adjacent to the first end portion 30a. The first supporting portion 31 is disposed inside the first bearing holding portion 20. The first supporting portion 31 is formed integrally with the rotary shaft 30. The first supporting portion 31 projects from the outer peripheral surface 300 of the rotary shaft 30.

The second supporting portion 32 is formed in a part of the outer peripheral surface 300 of the rotary shaft 30 adjacent to the second end portion 30b. The second supporting portion 32 is disposed inside the second bearing holding portion 21. The second supporting portion 32 is fixed to the outer peripheral surface 300 of the rotary shaft 30, and extends from the outer peripheral surface 300 of the rotary shaft 30 so as to have a ring shape. The second supporting portion 32 is rotatable together with the rotary shaft 30.

The support plate 33 is accommodated in the thrust bearing accommodation chamber S2. The support plate 33 is fixed to the outer peripheral surface 300 of the rotary shaft 30, and extends radially and outwardly from the outer peripheral surface 300 of the rotary shaft 30 so as to have a ring shape. That is, the support plate 33 is formed separately from the rotary shaft 30. The support plate 33 is rotatable together with the rotary shaft 30.

<Compressor Impeller 34>

The centrifugal compressor 10 includes a compressor impeller 34. The compressor impeller 34 is mounted on the first end portion 30a of the rotary shaft 30 in the axial direction of the rotary shaft 30. The compressor impeller 34 is disposed between the support plate 33 and the first end portion 30a of the rotary shaft 30. The compressor impeller 34 is accommodated in the impeller chamber 13b. That is, the housing 11 has the impeller chamber 13b in which the compressor impeller 34 is accommodated. The housing 11 accommodates the rotary shaft 30 and the compressor impeller 34. That is, the centrifugal compressor 10 includes the housing 11 accommodating the rotary shaft 30 and the compressor impeller 34. The compressor impeller 34 is rotated together with the rotary shaft 30.

<Turbine Wheel 35>

The centrifugal compressor 10 includes a turbine wheel 35. The turbine wheel 35 is mounted on the second end portion 30b of the rotary shaft 30. The turbine wheel 35 is disposed between the second supporting portion 32 and the second end portion 30b of the rotary shaft 30. The turbine wheel 35 is accommodated in the turbine chamber 14b. The turbine wheel 35 is rotated together with the rotary shaft 30.

<Configuration of Electric Motor 40>

The electric motor 40 includes a cylindrical rotor 41 and a cylindrical stator 42. The rotor 41 is fixed to the rotary shaft 30. The stator 42 is fixed in the housing 11. The rotor 41 is disposed radially inside the stator 42 and rotated together with the rotary shaft 30. The rotor 41 includes a cylindrical rotor core 41a fixed to the rotary shaft 30 and a plurality of permanent magnets, which is not illustrated, disposed in the rotor core 41a. The stator 42 surrounds the rotor 41. The stator 42 includes a stator core 43 and a coil 44. The stator core 43 has a cylindrical shape and is fixed to an inner peripheral surface 121b of the peripheral wall 12b of the motor housing 12. The coil 44 is wound around the stator core 43. The coil 44 receives current from a battery (not illustrated) so that the rotor 41 is rotated together with the rotary shaft 30. That is, the electric motor 40 is configured to rotate the rotary shaft 30. The electric motor 40 is disposed between the compressor impeller 34 and the turbine wheel 35 in the axial direction of the rotary shaft 30.

<First Radial Bearing 50 and Second Radial Bearing 51>

The centrifugal compressor 10 includes a first radial bearing 50 and a second radial bearing 51. The first radial bearing 50 has a cylindrical shape. The first radial bearing 50 is held by the first bearing holding portion 20. The second radial bearing 51 has a cylindrical shape. The second radial bearing 51 is held by the second bearing holding portion 21. The first radial bearing 50 and the second radial bearing 51 support the rotary shaft 30 in a radial direction such that the rotary shaft 30 is rotatable relative to the housing 11. The radial direction is a direction perpendicular to the axial direction of the rotary shaft 30.

<First Thrust Bearing 60 and Second Thrust Bearing 61>

As illustrated in FIG. 2, the centrifugal compressor 10 includes a thrust bearing, which, in this embodiment, is a first thrust bearing 60 and a second thrust bearing 61. The first thrust bearing 60 and the second thrust bearing 61 support the support plate 33 in a thrust direction such that the support plate 33 is rotatable relative to the housing 11. The thrust direction is a direction parallel to the axial direction of the rotary shaft 30.

The first thrust bearing 60 and the second thrust bearing 61 are accommodated in the thrust bearing accommodation chamber S2. That is, the housing 11 has the thrust bearing accommodation chamber S2 in which the first thrust bearing 60 and the second thrust bearing 61 are accommodated. The first thrust bearing 60 and the second thrust bearing 61 are disposed so as to hold therebetween the support plate 33. The second thrust bearing 61 and the support plate 33 are disposed between the compressor impeller 34 and the first thrust bearing 60. The second thrust bearing 61 is disposed between the compressor impeller 34 and the support plate 33. The first thrust bearing 60 has a first thrust bearing main body 60a and a first base portion 60b. The first base portion 60b has a disc shape. The first base portion 60b has a first through hole 60c through which the rotary shaft 30 is inserted. The second thrust bearing 61 has a second thrust bearing main body 61a and a second base portion 61b. The second base portion 61b has a disc shape. The second base portion 61b has a second through hole 61c through which the rotary shaft 30 is inserted.

<Fuel Cell System 1>

As illustrated in FIG. 1, the centrifugal compressor 10 serves as a part of a fuel cell system 1 mounted on a fuel cell vehicle. The fuel cell system 1 includes the centrifugal compressor 10, a fuel cell stack 100, a supply passage L1, a discharge passage L2, and a branched passage L3. The fuel cell stack 100 includes a plurality of fuel cells. For convenience of explanation, individual fuel cells of the fuel cell stack 100 are not illustrated in drawings. The fuel cell stack 100 is connected to the discharge chamber 13c through the supply passage L1. The fuel cell stack 100 is also connected to the suction chamber 14c through the discharge passage L2.

When the rotary shaft 30 rotates together with the rotor 41, the compressor impeller 34 and the turbine wheel 35 are rotated together with the rotary shaft 30. Air, which has been drawn through the inlet 13a, is compressed by the compressor impeller 34 in the impeller chamber 13b, and discharged from the discharge chamber 13c through the first diffuser passage 13d. That is, the compressor impeller 34 is rotated together with the rotary shaft 30 to compress air.

The air discharged from the discharge chamber 13c is supplied to the fuel cell stack 100 through the supply passage L1. The air supplied to the fuel cell stack 100 is used for electricity generation by the fuel cell stack 100. The used air is then discharged as exhaust from the fuel cell stack 100 to the discharge passage L2. The exhaust from the fuel cell stack 100 is drawn into the suction chamber 14c through the discharge passage L2. The exhaust drawn into the suction chamber 14c is then discharged to the turbine chamber 14b through the second diffuser passage 14d. The exhaust discharged into the turbine chamber 14b rotates the turbine wheel 35. The rotary shaft 30 is driven to rotate by the electric motor 40, and also by the rotation of the turbine wheel 35 by the exhaust from the fuel cell stack 100. The rotation of the turbine wheel 35 by the exhaust from the fuel cell stack 100 assists the rotation of the rotary shaft 30. The exhaust discharged into the turbine chamber 14b is discharged outside from the outlet 14a.

<Cooling Gas Passage G1 and Air in Cooling Gas Passage G1>

As illustrated in FIGS. 2 and 3, the seal plate 17 further has a recess 17c at the center portion of the end face 17b of the seal plate 17. The recess 17c has a circular hole shape. Most of the opening of the recess 17c is closed by the second base portion 61b. The recess 17c of the seal plate 17 and the second base portion 61b cooperate to define a cooling gas passage G1. The cooling gas passage G1 is communicated with the thrust bearing accommodation chamber S2 through a gap between the second through hole 61c of the second base portion 61b and the rotary shaft 30.

The seal plate 17 has a communication hole 17e and a connecting passage G2. The communication hole 17e has a circular hole shape. The communication hole 17e is opened on the end face 17b of the seal plate 17. The recess 17c is connected to the communication hole 17e through the connecting passage G2. The connecting passage G2 extends from the cooling gas passage G1 outwardly in the radial direction of the rotary shaft 30.

The first plate 15 has a through hole 15i. The through hole 15i is formed through the first plate 15 in the thickness direction of the first plate 15. The through hole 15i is formed coaxially with the communication hole 17e. One end of the through hole 15i is communicated with the communication hole 17e. The other end of the through hole 15i is communicated with the motor chamber S1. The communication hole 17e is communicated with the motor chamber S1 through the through hole 15i. The cooling gas passage G1 is communicated with the motor chamber S1 through the connecting passage G2, the communication hole 17e, and the through hole 15i.

Cooling gas for cooling the first thrust bearing 60 and the second thrust bearing 61 flows through the cooling gas passage G1. Specifically, the first plate 15 has a first passage 71. The first passage 71 extends in the radial direction of the rotary shaft 30. One end of the first passage 71 is opened on an outer surface of the first plate 15. The other end of the first passage 71 is communicated with the thrust bearing accommodation chamber S2. The second plate 16 has a second passage 72. The second passage 72 extends in the radial direction of the rotary shaft 30. One end of the second passage 72 is opened on an outer surface of the second plate 16. The other end of the second passage 72 is communicated with a part of the shaft insertion hole 16a adjacent to the motor housing 12 with respect to the second sealing member 23.

The branched passage L3 branches off from the supply passage L1. The supply passage L1 is connected to the first passage 71 through the branched passage L3. An intercooler R1 is disposed in the branched passage L3. The intercooler R1 cools the air flowing through the branched passage L3.

The air compressed by the compressor impeller 34 and flowed through the supply passage L1 toward the fuel cell stack 100 partly flows into the first passage 71 through the branched passage L3. The air in the first passage 71 has been cooled by the intercooler R1 while flowing through the branched passage L3. The air in the first passage 71 then flows into the thrust bearing accommodation chamber S2, and cools the first thrust bearing 60 and the second thrust bearing 61. That is, cooling gas for cooling the first thrust bearing 60 and the second thrust bearing 61 is part of the air compressed by the compressor impeller 34.

The air in the thrust bearing accommodation chamber S2 then flows into the cooling gas passage G1 through the gap between the second through hole 61c of the second base portion 61b and the rotary shaft 30. The air in the cooling gas passage G1 flows into the motor chamber S1 through the connecting passage G2, the communication hole 17e, and the through hole 15i.

The air flowed into the motor chamber S1 cools the electric motor 40. The air in the motor chamber S1 partly flows into a gap between the first radial bearing 50 and the first supporting portion 31, and cools the first radial bearing 50. The air in the motor chamber S1, for example, flows through a gap between the rotor 41 and the stator 42, and the air then flows into a gap between the second radial bearing 51 and the second supporting portion 32 to cool the second radial bearing 51. The air flows through the gap between the second radial bearing 51 and the second supporting portion 32, and is discharged to the outside of the housing 11 through the shaft insertion hole 16a and the second passage 72.

<Cooling Water Passage W1>

The end face 17b of the seal plate 17 has a groove 17d. On the end face 17b of the seal plate 17, the groove 17d is disposed outward of the recess 17c in the radial direction of the rotary shaft 30, and extends in the circumferential direction of the rotary shaft 30 so as to surround the recess 17c. The groove 17d is meandering about the axis of the shaft insertion hole 17a. Specifically, the groove 17d is formed of parts extending toward the axis of the shaft insertion hole 17a and parts extending away from the axis of the shaft insertion hole 17a, and those parts are alternatingly arranged. The groove 17d extends in the circumferential direction of the rotary shaft 30 such that the groove 17d is located inside in the radial direction of the rotary shaft 30 with respect to the bolt insertion holes 17h. The groove 17d has a first end 170d and a second end 171d that circumferentially extend over the whole circumference of the seal plate 17. The opening of the groove 17d is closed by the first plate 15. The groove 17d and the bottom surface 15f of the first recess 15c of the first plate 15 cooperate to define a cooling water passage W1. The cooling water passage W1 is formed outward of the cooling gas passage G1 in the radial direction of the rotary shaft 30. Cooling water flowing through the cooling water passage W1 is prevented from leaking by a sealing member (not illustrated) disposed between the end face 17b of the seal plate 17 and the bottom surface 15f of the first recess 15c of the first plate 15.

As illustrated in FIG. 1, the centrifugal compressor 10 further includes a cooling water jacket 12c. The cooling water jacket 12c is formed in the peripheral wall 12b of the motor housing 12. The cooling water jacket 12c circumferentially extends over the whole circumference of the peripheral wall 12b.

As illustrated in FIG. 2, the cooling water jacket 12c is connected to a first end of the cooling water passage W1 through a connecting cooling water passage W2. The cooling water jacket 12c is also connected to a second end of the cooling water passage W1 through a connecting cooling water passage W3.

The cooling water jacket 12c is further connected to a first end and a second end of an external passage (not illustrated) through which cooling water (long life coolant) flows. The cooling water in the external passage is cooled by heat exchange with outside air by a radiator (not illustrated) disposed in the external passage. The cooling water circulates from the external passage, through the cooling water jacket 12c, the connecting cooling water passage W2, the cooling water passage W1, and the connecting cooling water passage W3 in this order, to the cooling water jacket 12c. That is, the cooling water flows through the cooling water passage W1. The cooling water flowing through the cooling water passage W1 cools the seal plate 17. That is, the seal plate 17 has therein the cooling gas passage G1 through which the cooling gas flows so as to cool the first thrust bearing 60 and the second thrust bearing 61 and the cooling water passage W1 through which the cooling water flows so as to cool the seal plate 17.

<Operation>

Next, the following will explain the operation of the centrifugal compressor according to the embodiment.

The seal plate 17 has therein the cooling gas passage G1. Air cools the first thrust bearing 60 and the second thrust bearing 61, and further cools the seal plate 17 while flowing through the cooling gas passage G1. The seal plate 17 further has therein the cooling water passage W1. The cooling water flowing through the cooling water passage W1 cools the seal plate 17. That is, the heat of the air compressed by the compressor impeller 34 is less likely to transfer, via the seal plate 17, to the first thrust bearing 60 and the second thrust bearing 61 accommodated in the thrust bearing accommodation chamber S2. Accordingly, the first thrust bearing 60 and the second thrust bearing 61 are efficiently cooled by the air. Further, the heat of the first thrust bearing 60 and the second thrust bearing 61 transfers to the cooling water flowing through the cooling water passage W1.

Advantageous Effects

The aforementioned embodiment provides following advantageous effects.

(1) The seal plate 17 has therein the cooling gas passage G1. This allows air to cool the seal plate 17 by flowing through the cooling gas passage G1, while cooling the first thrust bearing 60 and the second thrust bearing 61. The seal plate 17 further has therein the cooling water passage W1, so that the cooling water further cools the seal plate 17. That is, the heat of the air compressed by the compressor impeller 34 is less likely to transfer, via the seal plate 17, to the first thrust bearing 60 and the second thrust bearing 61 accommodated in the thrust bearing accommodation chamber S2. Accordingly, the first thrust bearing 60 and the second thrust bearing 61 are efficiently cooled by the air. Further, the heat of the first thrust bearing 60 and the second thrust bearing 61 transfers to the cooling water flowing through the cooling water passage W1. This allows an increase in the ability of the centrifugal compressor to cool the first thrust bearing 60 and the second thrust bearing 61.

(2) The cooling water passage W1 is formed outward of the cooling gas passage G1 in the radial direction of the rotary shaft 30. This configuration allows an increase in area of the cooling water passage W1, compared to a case where the cooling water passage W1 is formed inward of the cooling gas passage G1 in the radial direction of the rotary shaft 30. Accordingly, the seal plate 17 is efficiently cooled. That is, the heat of the fluid compressed by the compressor impeller 34 is less likely to transfer, via the seal plate 17, to the first thrust bearing 60 and the second thrust bearing 61 accommodated in the thrust bearing accommodation chamber S2. Further, the heat of the first thrust bearing 60 and the second thrust bearing 61 is more likely to transfer to the cooling water flowing through the cooling water passage W1. This allows a further increase in the ability of the centrifugal compressor to cool the first thrust bearing 60 and the second thrust bearing 61.

Modification Example

The aforementioned embodiment may be modified as below. The embodiment may be combined with the following modification examples within technically consistent range.

• • In the embodiment, the cooling water passage W1 may be formed inward of the cooling gas passage G1 in the radial direction of the rotary shaft 30.
  • In the embodiment, the groove 17d is not necessarily meandering. That is, the shape of the groove 17d is not particularly limited.
  • In the embodiment, the cooling water flowing through the cooling water passage W1 is not necessarily the same as the cooling water flowing in the cooling water jacket 12c. That is, the method for supplying cooling water to the cooling water passage W1 is not particularly limited.
  • According to the embodiment, air cools the first thrust bearing 60 and the second thrust bearing 61 in the thrust bearing accommodation chamber S2, and then flows into the cooling gas passage G1. However, the configuration is not limited thereto. For example, the air may flow first into the cooling gas passage G1, and then into the thrust bearing accommodation chamber S2 to cool the first thrust bearing 60 and the second thrust bearing 61.
  • According to the embodiment, the air compressed by the compressor impeller 34 partly flows into the cooling gas passage G1 to serve as a cooling gas, but it is not limited thereto. The cooling gas may be air that is not the air compressed by the compressor impeller 34.
  • In the embodiment, the centrifugal compressor 10 does not necessarily include the turbine wheel 35.
  • In the embodiment, the centrifugal compressor 10 may include a compressor impeller instead of the turbine wheel 35. That is, each of the opposite ends of the rotary shaft 30 may have a compressor impeller, and a fluid compressed by one of the compressor impellers may be compressed again by the other of the compressor impellers.
  • In the embodiment, for example, the drive source of the centrifugal compressor 10 may be an engine.
  • In the embodiment, the centrifugal compressor 10 is not necessarily mounted on a fuel cell vehicle. For example, the centrifugal compressor 10 may be used for an air conditioner to compress refrigerant as a fluid. The centrifugal compressor 10 is not limited to a compressor mounted on a vehicle.

Claims

1. A centrifugal compressor comprising: a rotary shaft;a compressor impeller mounted on the rotary shaft, and configured to rotate together with the rotary shaft to compress a fluid;a housing accommodating the rotary shaft and the compressor impeller; anda thrust bearing supporting the rotary shaft in a thrust direction such that the rotary shaft is rotatable, whereinthe housing includes: an impeller chamber in which the compressor impeller is accommodated;a thrust bearing accommodation chamber in which the thrust bearing is accommodated; anda partition wall separating the impeller chamber from the thrust bearing accommodation chamber, andthe partition wall has therein a cooling gas passage through which cooling gas flows to cool the thrust bearing and a cooling water passage through which cooling water flows to cool the partition wall.

2. The centrifugal compressor according to claim 1, wherein the cooling water passage is formed outward of the cooling gas passage in a radial direction of the rotary shaft.