Centrifugal compressor

Abstract

This centrifugal compressor is provided with: a rotating shaft; at least one compressor impeller attached to at least one of one side and the other side of the rotating shaft; a thrust disc portion provided on the rotating shaft and extending along a radial direction of the rotating shaft; at least one thrust bearing which is an air bearing, is disposed closer to the one side or the other side than the thrust disc portion, and is opposed to the thrust disc portion with a gap therebetween; a casing in which the rotating shaft and the thrust disc portion are rotatably accommodated, and which supports the at least one thrust bearing; and at least one cooling air supply line configured to supply cooling air from the outside of the casing to the gap from the inner side in the radial direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a centrifugal compressor.BACKGROUND ART

[0002] In order to improve efficiency of a fuel cell, air to be supplied to a cathode side of the fuel cell is compressed by a compressor (refer to PTL 1). PTL 1 discloses a two-stage compressor in which a low-pressure compressor impeller and a high-pressure compressor impeller are provided on a common shaft, and the shaft is driven by an electric motor. In the two-stage compressor, compressed air compressed by the low-pressure compressor impeller is further compressed by the high-pressure compressor impeller. The compressed air from the high-pressure compressor impeller is fed to the fuel cell to promote a fuel cell reaction.CITATION LISTPatent Literature[PTL 1] Japanese Unexamined Patent Application Publication No. 2015-187444SUMMARY OF INVENTIONTechnical Problem

[0004] In order to avoid a possibility that fuel oil is mixed into the fuel cell, in some cases, an air bearing is adopted as a bearing that supports a shaft of a compressor which supplies the compressed air to a fuel cell. According to PTL 1, cooling air is supplied to a thrust bearing, which is an air bearing, from an outside in a radial direction. The cooling air present in a gap formed between the thrust bearing, which is a stationary body, and a thrust plate, which is a rotating body facing the thrust bearing with the gap and rotating together with the shaft, is pushed out (pumped up) from an inside to the outside in the radial direction as the shaft rotates. Therefore, when the cooling air is supplied to the thrust bearing, which is an air bearing, from the outside in the radial direction, it is difficult to supply the cooling air to the thrust bearing, and thereby there is a possibility that the thrust bearing is insufficiently cooled.

[0005] In view of the above-described circumstances, at least one embodiment of the present disclosure aims to provide a centrifugal compressor that can effectively cool a thrust bearing, which is an air bearing.Solution to Problem

[0006] According to at least one embodiment of the present disclosure, there is provided a centrifugal compressor including a rotary shaft, at least one compressor impeller attached to at least one of one side and the other side of the rotary shaft, a thrust disc portion provided in the rotary shaft and extending along a radial direction of the rotary shaft, at least one thrust bearing, which is an air bearing, which is disposed on the one side or the other side of the rotary shaft with respect to the thrust disc portion, and which faces the thrust disc portion with a gap, a casing accommodating the rotary shaft and the thrust disc portion to be rotatable and supporting the at least one thrust bearing, and at least one cooling air supply line configured to supply cooling air from an outside of the casing into the gap from an inside in the radial direction.Advantageous Effects of Invention

[0007] According to at least one embodiment of the present disclosure, it is possible to provide a centrifugal compressor that can effectively cool a thrust bearing, which is an air bearingBRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor according to an embodiment of the present disclosure.

[0009] FIG. 2 is a schematic cross-sectional view taken along the axial direction of the centrifugal compressor according to the embodiment of the present disclosure.

[0010] FIG. 3 is a schematic cross-sectional view taken along the axial direction in a vicinity of a thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.

[0011] FIG. 4 is a schematic view when the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure is viewed from an outside in a radial direction.

[0012] FIG. 5 is a schematic view when a one side cooling air supply line according to the embodiment of the present disclosure is viewed from one side in the axial direction.

[0013] FIG. 6 is a schematic view when a cooling air exhaust line according to the embodiment of the present disclosure is viewed from the one side in the axial direction.

[0014] FIG. 7 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.

[0015] FIG. 8 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0016] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, and relative dispositions of components described as the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, and are merely examples for describing the present disclosure.Centrifugal Compressor

[0017] Each of FIGS. 1 and 2 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor 1 according to an embodiment of the present disclosure. The centrifugal compressor 1 according to some embodiments includes a rotary shaft 2, at least one compressor impeller 3 attached to at least one of one side and the other side of the rotary shaft 2 in the axial direction, a thrust disc portion 21 provided in the rotary shaft 2 and extending along a radial direction of the rotary shaft 2, at least one thrust bearing 4, which is an air bearing, which is disposed on the one side or the other side of the rotary shaft 2 with respect to the thrust disc portion 21, and which faces the thrust disc portion 21 with gaps S1 and S2, and a casing 5 accommodating the rotary shaft 2 and the thrust disc portion 21 to be rotatable and supporting the at least one thrust bearing 4.

[0018] Hereinafter, an extending direction of a central axis CA of the rotary shaft 2 will be defined as an axial direction of the rotary shaft 2, a direction orthogonal to the central axis CA will be defined as a radial direction of the rotary shaft 2, and a circumferential direction around the central axis CA will be defined as a circumferential direction of the rotary shaft 2. In the present disclosure, each of the axial direction, the radial direction, and the circumferential direction of the rotary shaft 2 may be simply referred to as the axial direction, the radial direction, and the circumferential direction. In the present disclosure, the term “along a certain direction” includes not only a certain direction but also a direction inclined with respect to the certain direction within a range of ±15°.Thrust Disc Portion

[0019] The thrust disc portion 21 may be formed integrally with the rotary shaft 2, or may be a separate body from the rotary shaft 2, and may be attached to the rotary shaft 2 by means of fitting, for example.Compressor Impeller

[0020] In the embodiment shown in FIGS. 1 and 2, the at least one compressor impeller 3 includes a one side impeller 31 and the other side impeller 32. The one side impeller 31 is attached to the one side (right side in the drawing) of the rotary shaft 2 in the axial direction. The other side impeller 32 is attached to the other side (left side in the drawing) of the rotary shaft 2 in the axial direction. In the shown embodiment, the one side impeller 31 and the other side impeller 32 include a centrifugal impeller configured to guide air guided along the axial direction to an outside in the radial direction. Hereinafter, each of the one side and the other side of the rotary shaft 2 in the axial direction may be simply referred to as the one side and the other side. Some embodiments of the present disclosure are also applicable to the centrifugal compressor 1 including only one of the one side impeller 31 and the other side impeller 32.

[0021] In the embodiment shown in FIGS. 1 and 2, the one side impeller 31 is a compressor impeller in a low-pressure stage, and the other side impeller 32 is a compressor impeller in a high-pressure stage. The centrifugal compressor 1 may further include a relay line 11 for guiding compressed air compressed by the one side impeller 31 to the other side impeller 32. The centrifugal compressor 1 may further include a compressed air supply line 13 for supplying the compressed air compressed by the other side impeller 32 to a cathode side of a fuel cell 12.Thrust Bearing

[0022] In the embodiment shown in FIGS. 1 and 2, at least one thrust bearing 4 includes a one side thrust bearing 41 and the other side thrust bearing 42. The one side thrust bearing 41 is an air bearing, is disposed on the one side with respect to the thrust disc portion 21, and faces the thrust disc portion 21 with a first gap S1. The other side thrust bearing 42 is an air bearing, is disposed on the other side with respect to the thrust disc portion 21, and faces the thrust disc portion 21 with a second gap S2.Casing

[0023] In the embodiment shown in FIGS. 1 and 2, the above-described casing 5 includes a bearing housing 51 accommodating the rotary shaft 2 and the thrust disc portion 21 to be rotatable and supporting the one side thrust bearing 41 and the other side thrust bearing 42. The casing 5 may further include a one side housing 52 disposed on the one side with respect to the bearing housing 51, and the other side housing 53 disposed on the other side with respect to the bearing housing 51. The one side housing 52 is fastened to the bearing housing 51, and accommodates the one side impeller 31 between the one side housing 52 and the bearing housing 51. The other side housing 53 is fastened to the bearing housing 51, and accommodates the other side impeller 32 between the other side housing 53 and the bearing housing 51.Journal Bearing

[0024] In the embodiment shown in FIGS. 1 and 2, the above-described centrifugal compressor 1 further includes a one side journal bearing 101 supporting the one side of the rotary shaft 2 to be rotatable, and the other side journal bearing 102 supporting the other side of the rotary shaft 2 to be rotatable. Each of the one side journal bearing 101 and the other side journal bearing 102 is an air bearing, is accommodated in the bearing housing 51, and is supported by the bearing housing 51. In the shown embodiment, the one side journal bearing 101 is disposed on the other side with respect to the thrust disc portion 21. The other side journal bearing 102 is disposed on the other side with respect to the one side journal bearing 101, and is disposed on the one side with respect to the other side impeller 32.Cooling Air Supply Line

[0025] As shown in FIGS. 1 and 2, the centrifugal compressor 1 according to some embodiments includes at least one cooling air supply line 6 configured to supply cooling air from the outside of the casing 5 into the first gap S1 or the second gap S2 from the inside in the radial direction. The “cooling air” may be air that can flow through the first gap S1 or the second gap S2 to cool the thrust bearing 4, and may be air at a normal temperature (0° C. or higher and 40° C. or lower), for example. The cooling air is supplied from the inside in the radial direction into at least one of the first gap S1 and the second gap S2 through the cooling air supply line 6.

[0026] According to the above-described configuration, the cooling air present in the gaps S1 and S2 is pushed out (pumped up) from the inside to the outside in the radial direction as the rotary shaft 2 rotates. Since the cooling air is pumped up, supply of the cooling air from the cooling air supply line 6 to the gaps S1 and S2 and a movement of the cooling air present in the gaps S1 and S2 to the outside in the radial direction are promoted. Therefore, a required amount of the cooling air is easily supplied to the gaps S1 and S2. This centrifugal compressor 1 can effectively cool the thrust bearing 4 which is an air bearing.First Gap and Second GapFIG. 3 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure. FIG. 4 is a schematic view when the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure is viewed from the outside in the radial direction. As shown in FIGS. 3 and 4, the first gap S1 is formed between the one-side end surface 22 of the thrust disc portion 21 and the other-side end surface 411 of the one side thrust bearing 41, which faces the end surface 22. The second gap S2 is formed between the other-side end surface 23 of the thrust disc portion 21 and the one-side end surface 421 of the other side thrust bearing 42, which faces the end surface 23.One Side Thrust Bearing and Other Side Thrust Bearing

[0028] In the embodiment shown in FIG. 4, the one side thrust bearing 41 includes a top foil 412 which is a thin metal plate having the end surface 411, and an elastic foil 413 disposed on the one side with respect to the top foil 412 and having elastically deformable flexibility when a thrust load is received by the top foil 412. The elastic foil 413 may be a bump foil (refer to FIG. 4) having a corrugated plate shape, or may be a mesh foil having a mesh shape. In the embodiment shown in FIG. 4, the one side thrust bearing 41 may further include a flat plate-shaped support plate 414 disposed on the one side with respect to the elastic foil 413 and supporting the elastic foil 413. The casing 5 includes a one side thrust bearing support portion 54 supporting the support plate 414 of the one side thrust bearing 41.

[0029] In the embodiment shown in FIG. 4, the other side thrust bearing 42 includes a top foil 422 which is a thin metal plate having the end surface 421, and an elastic foil 423 disposed on the other side with respect to the top foil 422 and having elastically deformable flexibility when the thrust load is received by the top foil 422. The elastic foil 423 may be a bump foil (refer to FIG. 4) having a corrugated plate shape, or may be a mesh foil having a mesh shape. In the embodiment shown in FIG. 4, the other side thrust bearing 42 may further include a flat plate-shaped support plate 424 disposed on the other side with respect to the elastic foil 423 and supporting the elastic foil 423. The casing 5 includes the other side thrust bearing support portion 55 supporting the support plate 424 of the other side thrust bearing 42. The one side thrust bearing 41 and the other side thrust bearing 42 are not limited to the embodiment shown in FIG. 4.

[0030] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the at least one cooling air supply line 6 includes a one side cooling air supply line 61 configured to supply the cooling air from the outside of the casing 5 into the first gap S1 from the inside in the radial direction.

[0031] According to the above-described configuration, since the cooling air is pumped up, the supply of the cooling air from the one side cooling air supply line 61 to the first gap S1 and the movement of the cooling air present in the first gap S1 to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the first gap S1. The one side thrust bearing 41 is cooled by the cooling air flowing through the first gap S1 from the inside toward the outside in the radial direction.

[0032] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the at least one cooling air supply line 6 includes the other side cooling air supply line 62 configured to supply the cooling air from the outside of the casing 5 into the second gap S2 from the inside in the radial direction.

[0033] According to the above-described configuration, since the cooling air is pumped up, the supply of the cooling air from the other side cooling air supply line 62 to the second gap S2 and the movement of the cooling air present in the second gap S2 to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the second gap S2. The other side thrust bearing 42 is cooled by the cooling air flowing through the second gap S2 from the inside toward the outside in the radial direction.

[0034] When the cooling air supply line 6 includes both the one side cooling air supply line 61 and the other side cooling air supply line 62, the one side cooling air supply line 61 and the other side cooling air supply line 62 are set as separate lines. In this manner, the amount of the cooling air fed to the first gap S1 and the second gap S2 is easily secured. In addition, since the cooling air is supplied to both the first gap S1 and the second gap S2 via the one side cooling air supply line 61 and the other side cooling air supply line 62, the thrust bearing 4 can be more effectively cooled.

[0035] FIG. 5 is a schematic view when the one side cooling air supply line 61 according to the embodiment of the present disclosure is viewed from the one side in the axial direction. In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1, 2, and 5, the one side cooling air supply line 61 includes an annular inner annular flow path 63 extending along the circumferential direction, and a cooling air supply flow path 64. The inner annular flow path 63 is formed inside the bearing housing 51 (casing 5), and is connected to the inside of the first gap S1 in the radial direction. The cooling air supply flow path 64 includes a supply side outer opening 641 formed on an outer surface 56 of the bearing housing 51 (casing 5), and a supply side inner opening 642 formed on the one side with respect to a connecting portion P1 of the inner annular flow path 63 with the first gap S1.

[0036] In some embodiments, as shown in FIGS. 1 and 2, a first air bleeding line 111 for introducing the compressed air flowing through the relay line 11 to the supply side outer opening 641 may be connected to the one side cooling air supply line 61. One end of the first air bleeding line 111 is connected to the relay line 11, and the other end is connected to the supply side outer opening 641. A portion of the compressed air flowing through the relay line 11 is bled into the one side cooling air supply line 61 via the first air bleeding line 111. In this embodiment, the cooling air flowing through the one side cooling air supply line 61 flows in the order of the first air bleeding line 111, the cooling air supply flow path 64, the inner annular flow path 63, and the first gap S1. In this embodiment, the cooling air can be supplied to the first gap S1 via the one side cooling air supply line 61 without providing a blower 103 (to be described later) in the centrifugal compressor 1. Therefore, a size increase of the centrifugal compressor 1 can be suppressed.

[0037] In some embodiments, as shown in FIGS. 1 and 2, the blower 103 for raising the pressure of the cooling air to be supplied into the supply side outer opening 641 may be connected to the one side cooling air supply line 61. In this embodiment, the cooling air flowing through the one side cooling air supply line 61 flows in the order of the blower 103, the cooling air supply flow path 64, the inner annular flow path 63, and the first gap S1.

[0038] According to the above-described configuration, the cooling air can be supplied into the inner annular flow path 63 from the outside of the bearing housing 51 (casing 5) through the cooling air supply flow path 64, and can be supplied into the first gap S1 from the inside in the radial direction.

[0039] In some embodiments, as shown in FIG. 5, the cooling air supply flow path 64 includes an annular outer annular flow path 65 extending along the circumferential direction, a plurality of inner supply flow paths 66, and an outer supply flow path 67. The outer annular flow path 65 is formed outside the inner annular flow path 63 in the radial direction. One end of each of the plurality of inner supply flow paths 66 is connected to the inner annular flow path 63, the other end is connected to the outer annular flow path 65, and the inner supply flow paths 66 are disposed at an interval from each other in the circumferential direction. One end of the outer supply flow path 67 is connected to the outer annular flow path 65, and the supply side outer opening 641 is formed at the other end.

[0040] In the shown embodiment, each of the outer supply flow path 67 and the plurality of inner supply flow paths 66 extends along the radial direction. The cooling air flowing through the cooling air supply flow path 64 flows in the order of the outer supply flow path 67, the outer annular flow path 65, the inner supply flow path 66, and the inner annular flow path 63.

[0041] According to the above-described configuration, the cooling air can be supplied from each of the plurality of inner supply flow paths 66 to a plurality of locations of the inner annular flow path 63 in the circumferential direction. Therefore, cooling can be performed by the cooling air over a relatively wide range of the first gap S1 in the circumferential direction.Other Side Cooling Air Supply Line

[0042] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the other side cooling air supply line 62 includes an annular inner annular flow path 68 extending along the circumferential direction, and a cooling air supply flow path 69. The inner annular flow path 68 is formed inside the bearing housing 51 (casing 5), and is connected to the inside of the second gap S2 in the radial direction. The cooling air supply flow path 69 includes an supply side outer opening 691 formed on the outer surface 56 of the bearing housing 51 (casing 5), and an supply side inner opening 692 formed on the other side with respect to a connecting portion P2 of the inner annular flow path 68 with the second gap S2.

[0043] As shown in FIGS. 1 and 2, the centrifugal compressor 1 according to some embodiments further includes a rotor 81 of an electric motor 8 and a stator 82 of the electric motor 8. The rotor 81 includes a permanent magnet 83, and is attached to the other side with respect to the thrust disc portion 21 of the rotary shaft 2. The stator 82 includes a stationary coil portion 85, and is disposed on an outer peripheral side of the rotor 81 to face the rotor 81 with a third gap S3. An electric motor accommodation space 57A accommodating the rotor 81 and the stator 82 of the electric motor 8 is formed inside the bearing housing 51.

[0044] The rotor 81 further includes a permanent magnet support portion 84 supporting the permanent magnet 83. The permanent magnet support portion 84 is attached to the rotary shaft 2. The stator 82 further includes a stationary coil portion support portion 86 supporting the stationary coil portion 85. The stationary coil portion support portion 86 is supported by the bearing housing 51.

[0045] In the embodiment shown in FIGS. 1 and 2, the centrifugal compressor 1 includes an electric centrifugal compressor configured to rotate the rotary shaft 2 in such a manner that the electric motor 8 is driven by supplying electric power to the electric motor 8 from an electric power source (not shown). Some embodiments of the present disclosure are also applicable to the centrifugal compressor 1 that does not include the electric motor 8.

[0046] In the embodiment shown in FIGS. 1 and 2, the cooling air supply flow path 69 includes annular other side supply flow paths 693 and 694 extending along the circumferential direction, the electric motor accommodation space 57A, and a gap 104 formed between the one side journal bearing 101 and the rotary shaft 2. The gap 104 communicates with each of the electric motor accommodation space 57A and the inner annular flow path 68.

[0047] The other side supply flow path 693 is formed on the other side with respect to a gap 105 formed between the electric motor accommodation space 57A and the other side journal bearing 102 in the bearing housing 51 and the rotary shaft 2. The other side supply flow path 693 extends along the radial direction, one end of which has an supply side outer opening 691, and the other end of which is connected to a gap 106. The gap 106 is a gap formed between the rotary shaft 2 and the bearing housing 51 on the other side with respect to the gap 105 and on the one side with respect to the other side impeller 32, and communicates with the gap 105 adjacent to the one side. The other side supply flow path 694 extends along the axial direction, one end of which is connected to the other side supply flow path 693, and the other end of which is connected to the electric motor accommodation space 57A.

[0048] In some embodiments, as shown in FIGS. 1 and 2, a second air bleeding line 112 for supplying the compressed air flowing through the relay line 11 to the supply side outer opening 691 may be connected to the other side cooling air supply line 62. One end of the second air bleeding line 112 is connected to the relay line 11, and the other end is connected to the supply side outer opening 691. A portion of the compressed air flowing through the relay line 11 is bled into the other side cooling air supply line 62 via the second air bleeding line 112. In this embodiment, for example, at least a portion of the cooling air flowing through the other side cooling air supply line 62 flows in the order of the second air bleeding line 112, the other side supply flow paths 693 and 694, the electric motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. At least a portion of the cooling air flowing through the other side cooling air supply line 62 may flow in the order of the second air bleeding line 112, the other side supply flow path 693, the gap 106, the gap 105, the electric motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. In this embodiment, the cooling air can be supplied to the second gap S2 via the other side cooling air supply line 62 without providing a blower 107 (to be described later) in the centrifugal compressor 1. Therefore, a size increase of the centrifugal compressor 1 can be suppressed.

[0049] In some embodiments, as shown in FIGS. 1 and 2, the blower 107 for raising the pressure of the cooling air supplied into the supply side outer opening 691 may be connected to the other side cooling air supply line 62. In this embodiment, the cooling air is supplied from the blower 107 to the other side cooling air supply line 62.

[0050] According to the above-described configuration, the cooling air can be supplied into the inner annular flow path 68 from the outside of the bearing housing 51 (casing 5) through the cooling air supply flow path 69, and can be supplied into the second gap S2 from the inside in the radial direction.Cooling Air Exhaust LineFIG. 6 is a schematic view when a cooling air exhaust line 7 according to the embodiment of the present disclosure is viewed from the one side in the axial direction. As shown in FIGS. 1, 2, and 6, the centrifugal compressor 1 according to some embodiments further includes the cooling air exhaust line 7 for exhausting the cooling air to the outside of the bearing housing 51 (casing 5) from each of the first gap S1 and the second gap S2.

[0052] The cooling air exhaust line 7 includes an annular exhaust side annular flow path 71 extending along the circumferential direction, and a cooling air exhaust flow path 72. The exhaust side annular flow path 71 is formed inside the bearing housing 51 (casing 5), and is connected to the outside of the first gap S1 and the second gap S2 in the radial direction. The cooling air exhaust flow path 72 includes an exhaust side outer opening 721 formed on the outer surface 56 of the bearing housing 51 (casing 5), and an exhaust side inner opening 722 formed in the exhaust side annular flow path 71. The cooling air flows in the order of the exhaust side annular flow path 71 and the cooling air exhaust flow path 72 from each of the first gap S1 and the second gap S2, and thereafter, the cooling air is exhausted to the outside of the bearing housing 51. In the embodiment shown in FIG. 1, the cooling air exhaust flow path 72 extends along the radial direction.

[0053] According to the above-described configuration, the cooling air cooling the thrust bearing 4 after flowing through the gaps S1 and S2 can be exhausted to the outside of the casing 5 by the cooling air exhaust line 7. When the cooling air supply line 6 includes both the one side cooling air supply line 61 and the other side cooling air supply line 62, the cooling air is exhausted to the outside of the casing 5 through the common cooling air exhaust line 7 from the first gap S1 and the second gap S2. In this manner, a size increase of the casing 5 can be suppressed, and ultimately, a size increase of the centrifugal compressor 1 can be suppressed.

[0054] In some embodiments, as shown in FIG. 2, the cooling air exhaust flow path 72 includes an internal space 57 formed inside the bearing housing 51 (casing 5) and having a volume larger than a volume of the exhaust side annular flow path 71.

[0055] According to the above-described configuration, the internal space 57 having the volume larger than the volume of the exhaust side annular flow path 71 is provided in the cooling air exhaust flow path 72. In this manner, the formation of a circulation flow, that is, an inward flow of the cooling air from the outside inside the thrust bearing 4 in the radial direction, can be suppressed in the thrust bearing 4, which is an air bearing. Therefore, the flow of the cooling air from the exhaust side annular flow path 71 to the internal space 57 is promoted. In addition, since formation of the circulation flow in the thrust bearing 4 is suppressed, collision of the circulation flow with the cooling air supplied to the gaps S1 and S2 can be suppressed. Therefore, the supply of the cooling air to the gaps S1 and S2 is promoted.

[0056] In some embodiments, as shown in FIG. 2, the internal space 57, which is a portion of the cooling air exhaust flow path 72, includes the electric motor accommodation space 57A. In the embodiment shown in FIG. 2, the cooling air exhaust flow path 72 includes a communication flow path 72A, one end of which is connected to the exhaust side annular flow path 71 and the other end of which is connected to the electric motor accommodation space 57A at a position in the radial direction outside the exhaust side annular flow path 71 and the stationary coil portion 85 in the radial direction.

[0057] According to the above-described configuration, since the electric motor accommodation space 57A is used as the internal space 57 provided in the cooling air exhaust flow path 72, the internal space 57 does not need to be separately formed inside the casing 5. Therefore, a size increase of the casing 5 can be suppressed, and ultimately, a size increase of the centrifugal compressor 1 can be suppressed.Shielding Portion

[0058] Each of FIGS. 7 and 8 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure. In some embodiments, as shown in FIGS. 7 and 8, the one side thrust bearing 41 includes at least one through-hole 43 (in the shown example, a plurality of through-holes 43) penetrating along the radial direction. The centrifugal compressor 1 further includes a shielding portion 9 covering an outer peripheral side (outside in the radial direction) of the plurality of through-holes 43 and inhibiting the inflow of the gas into the plurality of through-holes 43.

[0059] As shown in FIG. 4, the through-hole 43 may be formed between the top foil 412 and the elastic foil 413, or may be formed between the elastic foil 413 and the support plate 414. It is preferable that a gap between the shielding portion 9 and the one side thrust bearing 41 is small. As shown in FIG. 7, the shielding portion 9 may be attached to the one side thrust bearing support portion 54, or may be formed integrally with the one side thrust bearing support portion 54. In addition, the shielding portion 9 may be formed integrally with the one side thrust bearing 41. The shielding portion 9 may be attached to the one side thrust bearing 41. In the embodiment shown in FIG. 8, the shielding portion 9 is formed by bending an outer peripheral end portion of the support plate 414.

[0060] In some embodiments, as shown in FIGS. 7 and 8, the other side thrust bearing 42 includes at least one through-hole 43A (in the shown example, a plurality of through-holes 43A) penetrating along the radial direction. The centrifugal compressor 1 further includes a shielding portion 9A covering an outer peripheral side (outside in the radial direction) of the plurality of through-holes 43A and inhibiting the inflow of the gas into the plurality of through-holes 43A.

[0061] As shown in FIG. 4, the through-hole 43A may be formed between the top foil 422 and the elastic foil 423, or may be formed between the elastic foil 423 and the support plate 424. It is preferable that a gap between the shielding portion 9A and the other side thrust bearing 42 is small. As shown in FIG. 7, the shielding portion 9A may be attached to the other side thrust bearing support portion 55, or may be formed integrally with the other side thrust bearing support portion 55. In addition, the shielding portion 9A may be formed integrally with the other side thrust bearing 42. The shielding portion 9A may be attached to the other side thrust bearing 42. In the embodiment shown in FIG. 8, the shielding portion 9A is formed by bending an outer peripheral end portion of the support plate 424.

[0062] According to the above-described configuration, since the shielding portions 9 and 9A are provided, the inflow of the cooling air into the through-holes 43 and 43A of the thrust bearing 4 can be inhibited. Therefore, the formation of the circulation flow, that is, the inward flow of the cooling air from the outside in the radial direction through the through-holes 43 and 43A of the thrust bearing 4, can be suppressed in the thrust bearing 4. In this manner, exhausting the cooling air from the exhaust side annular flow path 71 is promoted. In addition, since formation of the circulation flow in the thrust bearing 4 is suppressed, collision of the circulation flow with the cooling air supplied to the gaps S1 and S2 can be suppressed. Therefore, the supply of the cooling air to the gaps S1 and S2 is promoted.

[0063] In the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.

[0064] For example, expressions representing that things are in an equal state such as “same”, “equal”, and “homogeneous” not only strictly represent an equal state, but also represent a state where a difference exists with a tolerance or to such an extent that the same function can be obtained.

[0065] In addition, in the present specification, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

[0066] In addition, in the present specification, expressions such as “being provided with”, “including”, and “having” one component are not exclusive expressions excluding the presence of other components.

[0067] The present disclosure is not limited to the above-described embodiments, and also includes a form in which modifications are added to the above-described embodiments or a form in which the embodiments are combined with each other as appropriate.

[0068] Contents described in some embodiments described above are understood as follows, for example.

[0069] 1) The centrifugal compressor (1) according to at least one embodiment of the present disclosure includes the rotary shaft (2), at least one compressor impeller (3) attached to at least one of one side and the other side of the rotary shaft (2), the thrust disc portion (21) provided in the rotary shaft (2) and extending along the radial direction of the rotary shaft (2), at least one thrust bearing (4), which is an air bearing, which is disposed on the one side or the other side of the rotary shaft (2) with respect to the thrust disc portion (21), and which faces the thrust disc portion (21) with the gaps (S1 and S2), the casing (5) accommodating the rotary shaft (2) and the thrust disc portion (21) to be rotatable and supporting the at least one thrust bearing (4), and at least one cooling air supply line (6) configured to supply the cooling air from the outside of the casing (5) into the gaps (S1 and S2) from the inside in the radial direction.

[0070] According to the configuration of 1) above, the cooling air present in the gaps (S1 and S2) is pushed out (pumped up) from the inside to the outside in the radial direction as the rotary shaft (2) rotates. Since the cooling air is pumped up, the supply of the cooling air from the cooling air supply line (6) to the gaps (S1 and S2) and the movement of the cooling air present in the gaps (S1 and S2) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the gaps (S1 and S2). This centrifugal compressor (1) can effectively cool the thrust bearing (4), which is an air bearing.

[0071] 2) In some embodiments, in the centrifugal compressor (1) according to 1), the at least one compressor impeller (3) includes the one side impeller (31) attached to the one side of the rotary shaft (2), the at least one thrust bearing (4) includes the one side thrust bearing (41) disposed on the one side of the rotary shaft (2) with respect to the thrust disc portion (21) and facing the thrust disc portion (21) with the first gap (S1), and the at least one cooling air supply line (6) includes the one side cooling air supply line (61) configured to supply the cooling air from the outside of the casing (5) into the first gap (S1) from the inside in the radial direction.

[0072] According to the configuration of 2) above, since the cooling air is pumped up, the supply of the cooling air from the one side cooling air supply line (61) to the first gap (S1) and the movement of the cooling air present in the first gap (S1) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the first gap (S1).

[0073] 3) In some embodiments, in the centrifugal compressor (1) according to 1) or 2), the at least one compressor impeller (3) includes the other side impeller (32) attached to the other side of the rotary shaft (2), the at least one thrust bearing (4) includes the other side thrust bearing (42) disposed on the one side of the rotary shaft (2) with respect to the thrust disc portion (21) and facing the thrust disc portion (21) with the second gap (S2), and the at least one cooling air supply line (6) includes the other side cooling air supply line (62) configured to supply the cooling air from the outside of the casing (5) into the second gap (S2) from the inside in the radial direction.

[0074] According to the configuration of 3) above, since the cooling air is pumped up, the supply of the cooling air from the other side cooling air supply line (62) to the second gap (S2) and the movement of the cooling air present in the second gap (S2) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the second gap (S2). When the cooling air supply line (6) includes both the one side cooling air supply line (61) and the other side cooling air supply line (62), the one side cooling air supply line (61) and the other side cooling air supply line (62) are set as separate lines. In this manner, the amount of the cooling air fed to the first gap (S1) and the second gap (S2) is easily secured. In addition, since the cooling air is supplied to both the first gap (S1) and the second gap (S2) via the one side cooling air supply line (61) and the other side cooling air supply line (62), the thrust bearing (4) can be more effectively cooled.

[0075] 4) In some embodiments, in the centrifugal compressor (1) according to 2), the one side cooling air supply line (61) includes the annular inner annular flow path (63) formed inside the casing (5) and connected to the inside of the first gap (S1) in the radial direction, and the cooling air supply flow path (64) including the supply side outer opening (641) formed on the outer surface (56) of the casing (5), and the supply side inner opening (642) formed on the one side with respect to the connecting portion of the inner annular flow path (63) with the first gap (S1).

[0076] According to the configuration of 4) above, the cooling air can be supplied into the inner annular flow path (63) from the outside of the casing (5) through the cooling air supply flow path (64), and can be supplied into the first gap (S1) from the inside in the radial direction.

[0077] 5) In some embodiments, in the centrifugal compressor (1) according to 4), the cooling air supply flow path (64) includes the outer annular flow path (65) formed outside the inner annular flow path (63) in the radial direction, the plurality of inner supply flow paths (66) in which one end is connected to the inner annular flow path (63) and the other end is connected to the outer annular flow path (65), the plurality of inner supply flow paths (66) being disposed at an interval from each other in the circumferential direction of the rotary shaft (2), and the outer supply flow path (67) in which one end is connected to the outer annular flow path (65) and the supply side outer opening (641) is formed at the other end.

[0078] According to the configuration of 5) above, the cooling air can be supplied from each of the plurality of inner supply flow paths (66) to the plurality of locations of the inner annular flow path (63) in the circumferential direction. Therefore, cooling can be performed by the cooling air over a relatively wide range of the first gap (S1) in the circumferential direction.

[0079] 6) In some embodiments, the centrifugal compressor (1) according to any one of 1) to 5) further includes the cooling air exhaust line (7) for exhausting the cooling air to the outside of the casing (5) from the gaps (S1 and S2). The cooling air exhaust line (7) includes the annular exhaust side annular flow path (71) formed inside the casing (5) and connected to the outside of the gaps (S1 and S2) in the radial direction, and the cooling air exhaust flow path (72) including the exhaust side outer opening (721) formed on the outer surface (56) of the casing (5), and the exhaust side inner opening (722) formed in the exhaust side annular flow path (71).

[0080] According to the configuration of 6) above, the cooling air cooling the thrust bearing (4) after flowing through the gaps (S1 and S2) can be exhausted to the outside of the casing (5) by the cooling air exhaust line (7). When the cooling air supply line (6) includes both the one side cooling air supply line (61) and the other side cooling air supply line (62), the cooling air is exhausted to the outside of the casing (5) through the common cooling air exhaust line (7) from the first gap (S1) and the second gap (S2). In this manner, a size increase of the casing (5) can be suppressed, and ultimately, a size increase of the centrifugal compressor (1) can be suppressed.

[0081] 7) In some embodiments, in the centrifugal compressor (1) according to 6), the cooling air exhaust flow path (72) includes the internal space (57) formed inside the casing (5) and having the volume larger than the volume of the exhaust side annular flow path (71).

[0082] According to the configuration of 7) above, the internal space (57) having the volume larger than the volume of the exhaust side annular flow path (71) is provided in the cooling air exhaust flow path (72). In this manner, formation of the circulation flow in the thrust bearing (4), which is an air bearing, can be suppressed. Therefore, the flow of the cooling air from the exhaust side annular flow path (71) to the internal space (57) is promoted. In addition, since formation of the circulation flow in the thrust bearing (4) is suppressed, collision of the circulation flow with the cooling air supplied to the gaps (S1 and S2) can be suppressed. Therefore, the supply of the cooling air to the gaps (S1 and S2) is promoted.

[0083] 8) In some embodiments, the centrifugal compressor (1) according to 7) further includes the rotor (81) of the electric motor (8) including the permanent magnet (83) and attached to the other side of the rotary shaft (2) with respect to the thrust disc portion (21), and the stator (82) of the electric motor (8) including the stationary coil portion (85) and disposed on the outer peripheral side of the rotor (81) to face the rotor (81) with the third gap (S3). The internal space (57) includes the electric motor accommodation space (57A) accommodating the rotor (81) and the stator (82) of the electric motor (8).

[0084] According to the configuration of 8) above, the electric motor accommodation space (57A) is used as the internal space (57) provided in the cooling air exhaust flow path (72). In this manner, the internal space (57) does not need to be separately formed inside the casing (5). Therefore, a size increase of the casing (5) can be suppressed, and ultimately, a size increase of the centrifugal compressor (1) can be suppressed.

[0085] 9) In some embodiments, in the centrifugal compressor (1) according to any one of 1) to 8), the at least one thrust bearing (4) includes at least one through-hole (43 and 43A) penetrating along the radial direction, and the centrifugal compressor (1) further includes the shielding portion (9) covering the outer peripheral side of the at least one through-hole (43 and 43A) and inhibiting the inflow of the gas into the at least one through-hole (43 and 43A).

[0086] According to the configuration of 9) above, since the shielding portion (9) is provided, the inflow of the cooling air into the through-holes (43 and 43A) of the thrust bearing (4) can be inhibited. Therefore, formation of the circulation flow in the thrust bearing (4) can be suppressed. In this manner, exhausting the cooling air from the exhaust side annular flow path (71) is promoted. In addition, since formation of the circulation flow in the thrust bearing (4) is suppressed, collision of the circulation flow with the cooling air supplied to the gaps (S1 and S2) can be suppressed. Therefore, the supply of the cooling air to the gaps (S1 and S2) is promoted.REFERENCE SIGNS LIST1: centrifugal compressor

[0088] 2: rotary shaft

[0089] 3: compressor impeller

[0090] 4: thrust bearing

[0091] 5: casing

[0092] 6: cooling air supply line

[0093] 7: cooling air exhaust line

[0094] 8: electric motor

[0095] 9, 9A: shielding portion

[0096] 11: relay line

[0097] 12: fuel cell

[0098] 13: compressed air supply line

[0099] 21: thrust disc portion

[0100] 31: one side impeller

[0101] 32: other side impeller

[0102] 41: one side thrust bearing

[0103] 42: other side thrust bearing

[0104] 43, 43A: through-hole

[0105] 51: bearing housing

[0106] 52: one side housing

[0107] 53: other side housing

[0108] 54: one side thrust bearing support portion

[0109] 55: other side thrust bearing support portion

[0110] 56: outer surface

[0111] 57: internal space

[0112] 57A: electric motor accommodation space

[0113] 61: one side cooling air supply line

[0114] 62: other side cooling air supply line

[0115] 63, 68: inner annular flow path

[0116] 64, 69: cooling air supply flow path

[0117] 65: outer annular flow path

[0118] 66: inner supply flow path

[0119] 67: outer supply flow path

[0120] 71: exhaust side annular flow path

[0121] 72: cooling air exhaust flow path

[0122] 81: rotor

[0123] 82: stator

[0124] 83: permanent magnet

[0125] 84: permanent magnet support portion

[0126] 85: stationary coil portion

[0127] 86: stationary coil portion support portion

[0128] 101, 102: journal bearing

[0129] 103, 107: blower

[0130] 104, 105, 106: gap

[0131] 111: first air bleeding line

[0132] 112: second air bleeding line

[0133] 412, 422: top foil

[0134] 413, 423: elastic foil

[0135] 414, 424: support plate

[0136] 641, 691: supply side outer opening

[0137] 642, 692: supply side inner opening

[0138] 721: exhaust side outer opening

[0139] 722: exhaust side inner opening

[0140] CA: central axis

[0141] P1, P2: connecting portion

[0142] S1: first gap

[0143] S2: second gap

[0144] S3: third gap

Examples

Embodiment Construction

[0016]Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, and relative dispositions of components described as the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, and are merely examples for describing the present disclosure.

Centrifugal Compressor

[0017]Each of FIGS. 1 and 2 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor 1 according to an embodiment of the present disclosure. The centrifugal compressor 1 according to some embodiments includes a rotary shaft 2, at least one compressor impeller 3 attached to at least one of one side and the other side of the rotary shaft 2 in the axial direction, a thrust disc portion 21 provided in the rotary shaft 2 and extending along a radial direction of the rotary shaft 2, at least one thrust bearing 4, which is an air bearing, which is dispos...

TECHNICAL FIELD

[0001] The present disclosure relates to a centrifugal compressor.BACKGROUND ART

[0002] In order to improve efficiency of a fuel cell, air to be supplied to a cathode side of the fuel cell is compressed by a compressor (refer to PTL 1). PTL 1 discloses a two-stage compressor in which a low-pressure compressor impeller and a high-pressure compressor impeller are provided on a common shaft, and the shaft is driven by an electric motor. In the two-stage compressor, compressed air compressed by the low-pressure compressor impeller is further compressed by the high-pressure compressor impeller. The compressed air from the high-pressure compressor impeller is fed to the fuel cell to promote a fuel cell reaction.CITATION LISTPatent Literature[PTL 1] Japanese Unexamined Patent Application Publication No. 2015-187444SUMMARY OF INVENTIONTechnical Problem

[0004] In order to avoid a possibility that fuel oil is mixed into the fuel cell, in some cases, an air bearing is adopted as a bearing that supports a shaft of a compressor which supplies the compressed air to a fuel cell. According to PTL 1, cooling air is supplied to a thrust bearing, which is an air bearing, from an outside in a radial direction. The cooling air present in a gap formed between the thrust bearing, which is a stationary body, and a thrust plate, which is a rotating body facing the thrust bearing with the gap and rotating together with the shaft, is pushed out (pumped up) from an inside to the outside in the radial direction as the shaft rotates. Therefore, when the cooling air is supplied to the thrust bearing, which is an air bearing, from the outside in the radial direction, it is difficult to supply the cooling air to the thrust bearing, and thereby there is a possibility that the thrust bearing is insufficiently cooled.

[0005] In view of the above-described circumstances, at least one embodiment of the present disclosure aims to provide a centrifugal compressor that can effectively cool a thrust bearing, which is an air bearing.Solution to Problem

[0006] According to at least one embodiment of the present disclosure, there is provided a centrifugal compressor including a rotary shaft, at least one compressor impeller attached to at least one of one side and the other side of the rotary shaft, a thrust disc portion provided in the rotary shaft and extending along a radial direction of the rotary shaft, at least one thrust bearing, which is an air bearing, which is disposed on the one side or the other side of the rotary shaft with respect to the thrust disc portion, and which faces the thrust disc portion with a gap, a casing accommodating the rotary shaft and the thrust disc portion to be rotatable and supporting the at least one thrust bearing, and at least one cooling air supply line configured to supply cooling air from an outside of the casing into the gap from an inside in the radial direction.Advantageous Effects of Invention

[0007] According to at least one embodiment of the present disclosure, it is possible to provide a centrifugal compressor that can effectively cool a thrust bearing, which is an air bearingBRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor according to an embodiment of the present disclosure.

[0009] FIG. 2 is a schematic cross-sectional view taken along the axial direction of the centrifugal compressor according to the embodiment of the present disclosure.

[0010] FIG. 3 is a schematic cross-sectional view taken along the axial direction in a vicinity of a thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.

[0011] FIG. 4 is a schematic view when the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure is viewed from an outside in a radial direction.

[0012] FIG. 5 is a schematic view when a one side cooling air supply line according to the embodiment of the present disclosure is viewed from one side in the axial direction.

[0013] FIG. 6 is a schematic view when a cooling air exhaust line according to the embodiment of the present disclosure is viewed from the one side in the axial direction.

[0014] FIG. 7 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.

[0015] FIG. 8 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing of the centrifugal compressor according to the embodiment of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0016] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, and relative dispositions of components described as the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, and are merely examples for describing the present disclosure.Centrifugal Compressor

[0017] Each of FIGS. 1 and 2 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor 1 according to an embodiment of the present disclosure. The centrifugal compressor 1 according to some embodiments includes a rotary shaft 2, at least one compressor impeller 3 attached to at least one of one side and the other side of the rotary shaft 2 in the axial direction, a thrust disc portion 21 provided in the rotary shaft 2 and extending along a radial direction of the rotary shaft 2, at least one thrust bearing 4, which is an air bearing, which is disposed on the one side or the other side of the rotary shaft 2 with respect to the thrust disc portion 21, and which faces the thrust disc portion 21 with gaps S1 and S2, and a casing 5 accommodating the rotary shaft 2 and the thrust disc portion 21 to be rotatable and supporting the at least one thrust bearing 4.

[0018] Hereinafter, an extending direction of a central axis CA of the rotary shaft 2 will be defined as an axial direction of the rotary shaft 2, a direction orthogonal to the central axis CA will be defined as a radial direction of the rotary shaft 2, and a circumferential direction around the central axis CA will be defined as a circumferential direction of the rotary shaft 2. In the present disclosure, each of the axial direction, the radial direction, and the circumferential direction of the rotary shaft 2 may be simply referred to as the axial direction, the radial direction, and the circumferential direction. In the present disclosure, the term “along a certain direction” includes not only a certain direction but also a direction inclined with respect to the certain direction within a range of ±15°.Thrust Disc Portion

[0019] The thrust disc portion 21 may be formed integrally with the rotary shaft 2, or may be a separate body from the rotary shaft 2, and may be attached to the rotary shaft 2 by means of fitting, for example.Compressor Impeller

[0020] In the embodiment shown in FIGS. 1 and 2, the at least one compressor impeller 3 includes a one side impeller 31 and the other side impeller 32. The one side impeller 31 is attached to the one side (right side in the drawing) of the rotary shaft 2 in the axial direction. The other side impeller 32 is attached to the other side (left side in the drawing) of the rotary shaft 2 in the axial direction. In the shown embodiment, the one side impeller 31 and the other side impeller 32 include a centrifugal impeller configured to guide air guided along the axial direction to an outside in the radial direction. Hereinafter, each of the one side and the other side of the rotary shaft 2 in the axial direction may be simply referred to as the one side and the other side. Some embodiments of the present disclosure are also applicable to the centrifugal compressor 1 including only one of the one side impeller 31 and the other side impeller 32.

[0021] In the embodiment shown in FIGS. 1 and 2, the one side impeller 31 is a compressor impeller in a low-pressure stage, and the other side impeller 32 is a compressor impeller in a high-pressure stage. The centrifugal compressor 1 may further include a relay line 11 for guiding compressed air compressed by the one side impeller 31 to the other side impeller 32. The centrifugal compressor 1 may further include a compressed air supply line 13 for supplying the compressed air compressed by the other side impeller 32 to a cathode side of a fuel cell 12.Thrust Bearing

[0022] In the embodiment shown in FIGS. 1 and 2, at least one thrust bearing 4 includes a one side thrust bearing 41 and the other side thrust bearing 42. The one side thrust bearing 41 is an air bearing, is disposed on the one side with respect to the thrust disc portion 21, and faces the thrust disc portion 21 with a first gap S1. The other side thrust bearing 42 is an air bearing, is disposed on the other side with respect to the thrust disc portion 21, and faces the thrust disc portion 21 with a second gap S2.Casing

[0023] In the embodiment shown in FIGS. 1 and 2, the above-described casing 5 includes a bearing housing 51 accommodating the rotary shaft 2 and the thrust disc portion 21 to be rotatable and supporting the one side thrust bearing 41 and the other side thrust bearing 42. The casing 5 may further include a one side housing 52 disposed on the one side with respect to the bearing housing 51, and the other side housing 53 disposed on the other side with respect to the bearing housing 51. The one side housing 52 is fastened to the bearing housing 51, and accommodates the one side impeller 31 between the one side housing 52 and the bearing housing 51. The other side housing 53 is fastened to the bearing housing 51, and accommodates the other side impeller 32 between the other side housing 53 and the bearing housing 51.Journal Bearing

[0024] In the embodiment shown in FIGS. 1 and 2, the above-described centrifugal compressor 1 further includes a one side journal bearing 101 supporting the one side of the rotary shaft 2 to be rotatable, and the other side journal bearing 102 supporting the other side of the rotary shaft 2 to be rotatable. Each of the one side journal bearing 101 and the other side journal bearing 102 is an air bearing, is accommodated in the bearing housing 51, and is supported by the bearing housing 51. In the shown embodiment, the one side journal bearing 101 is disposed on the other side with respect to the thrust disc portion 21. The other side journal bearing 102 is disposed on the other side with respect to the one side journal bearing 101, and is disposed on the one side with respect to the other side impeller 32.Cooling Air Supply Line

[0025] As shown in FIGS. 1 and 2, the centrifugal compressor 1 according to some embodiments includes at least one cooling air supply line 6 configured to supply cooling air from the outside of the casing 5 into the first gap S1 or the second gap S2 from the inside in the radial direction. The “cooling air” may be air that can flow through the first gap S1 or the second gap S2 to cool the thrust bearing 4, and may be air at a normal temperature (0° C. or higher and 40° C. or lower), for example. The cooling air is supplied from the inside in the radial direction into at least one of the first gap S1 and the second gap S2 through the cooling air supply line 6.

[0026] According to the above-described configuration, the cooling air present in the gaps S1 and S2 is pushed out (pumped up) from the inside to the outside in the radial direction as the rotary shaft 2 rotates. Since the cooling air is pumped up, supply of the cooling air from the cooling air supply line 6 to the gaps S1 and S2 and a movement of the cooling air present in the gaps S1 and S2 to the outside in the radial direction are promoted. Therefore, a required amount of the cooling air is easily supplied to the gaps S1 and S2. This centrifugal compressor 1 can effectively cool the thrust bearing 4 which is an air bearing.First Gap and Second GapFIG. 3 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure. FIG. 4 is a schematic view when the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure is viewed from the outside in the radial direction. As shown in FIGS. 3 and 4, the first gap S1 is formed between the one-side end surface 22 of the thrust disc portion 21 and the other-side end surface 411 of the one side thrust bearing 41, which faces the end surface 22. The second gap S2 is formed between the other-side end surface 23 of the thrust disc portion 21 and the one-side end surface 421 of the other side thrust bearing 42, which faces the end surface 23.One Side Thrust Bearing and Other Side Thrust Bearing

[0028] In the embodiment shown in FIG. 4, the one side thrust bearing 41 includes a top foil 412 which is a thin metal plate having the end surface 411, and an elastic foil 413 disposed on the one side with respect to the top foil 412 and having elastically deformable flexibility when a thrust load is received by the top foil 412. The elastic foil 413 may be a bump foil (refer to FIG. 4) having a corrugated plate shape, or may be a mesh foil having a mesh shape. In the embodiment shown in FIG. 4, the one side thrust bearing 41 may further include a flat plate-shaped support plate 414 disposed on the one side with respect to the elastic foil 413 and supporting the elastic foil 413. The casing 5 includes a one side thrust bearing support portion 54 supporting the support plate 414 of the one side thrust bearing 41.

[0029] In the embodiment shown in FIG. 4, the other side thrust bearing 42 includes a top foil 422 which is a thin metal plate having the end surface 421, and an elastic foil 423 disposed on the other side with respect to the top foil 422 and having elastically deformable flexibility when the thrust load is received by the top foil 422. The elastic foil 423 may be a bump foil (refer to FIG. 4) having a corrugated plate shape, or may be a mesh foil having a mesh shape. In the embodiment shown in FIG. 4, the other side thrust bearing 42 may further include a flat plate-shaped support plate 424 disposed on the other side with respect to the elastic foil 423 and supporting the elastic foil 423. The casing 5 includes the other side thrust bearing support portion 55 supporting the support plate 424 of the other side thrust bearing 42. The one side thrust bearing 41 and the other side thrust bearing 42 are not limited to the embodiment shown in FIG. 4.

[0030] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the at least one cooling air supply line 6 includes a one side cooling air supply line 61 configured to supply the cooling air from the outside of the casing 5 into the first gap S1 from the inside in the radial direction.

[0031] According to the above-described configuration, since the cooling air is pumped up, the supply of the cooling air from the one side cooling air supply line 61 to the first gap S1 and the movement of the cooling air present in the first gap S1 to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the first gap S1. The one side thrust bearing 41 is cooled by the cooling air flowing through the first gap S1 from the inside toward the outside in the radial direction.

[0032] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the at least one cooling air supply line 6 includes the other side cooling air supply line 62 configured to supply the cooling air from the outside of the casing 5 into the second gap S2 from the inside in the radial direction.

[0033] According to the above-described configuration, since the cooling air is pumped up, the supply of the cooling air from the other side cooling air supply line 62 to the second gap S2 and the movement of the cooling air present in the second gap S2 to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the second gap S2. The other side thrust bearing 42 is cooled by the cooling air flowing through the second gap S2 from the inside toward the outside in the radial direction.

[0034] When the cooling air supply line 6 includes both the one side cooling air supply line 61 and the other side cooling air supply line 62, the one side cooling air supply line 61 and the other side cooling air supply line 62 are set as separate lines. In this manner, the amount of the cooling air fed to the first gap S1 and the second gap S2 is easily secured. In addition, since the cooling air is supplied to both the first gap S1 and the second gap S2 via the one side cooling air supply line 61 and the other side cooling air supply line 62, the thrust bearing 4 can be more effectively cooled.

[0035] FIG. 5 is a schematic view when the one side cooling air supply line 61 according to the embodiment of the present disclosure is viewed from the one side in the axial direction. In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1, 2, and 5, the one side cooling air supply line 61 includes an annular inner annular flow path 63 extending along the circumferential direction, and a cooling air supply flow path 64. The inner annular flow path 63 is formed inside the bearing housing 51 (casing 5), and is connected to the inside of the first gap S1 in the radial direction. The cooling air supply flow path 64 includes a supply side outer opening 641 formed on an outer surface 56 of the bearing housing 51 (casing 5), and a supply side inner opening 642 formed on the one side with respect to a connecting portion P1 of the inner annular flow path 63 with the first gap S1.

[0036] In some embodiments, as shown in FIGS. 1 and 2, a first air bleeding line 111 for introducing the compressed air flowing through the relay line 11 to the supply side outer opening 641 may be connected to the one side cooling air supply line 61. One end of the first air bleeding line 111 is connected to the relay line 11, and the other end is connected to the supply side outer opening 641. A portion of the compressed air flowing through the relay line 11 is bled into the one side cooling air supply line 61 via the first air bleeding line 111. In this embodiment, the cooling air flowing through the one side cooling air supply line 61 flows in the order of the first air bleeding line 111, the cooling air supply flow path 64, the inner annular flow path 63, and the first gap S1. In this embodiment, the cooling air can be supplied to the first gap S1 via the one side cooling air supply line 61 without providing a blower 103 (to be described later) in the centrifugal compressor 1. Therefore, a size increase of the centrifugal compressor 1 can be suppressed.

[0037] In some embodiments, as shown in FIGS. 1 and 2, the blower 103 for raising the pressure of the cooling air to be supplied into the supply side outer opening 641 may be connected to the one side cooling air supply line 61. In this embodiment, the cooling air flowing through the one side cooling air supply line 61 flows in the order of the blower 103, the cooling air supply flow path 64, the inner annular flow path 63, and the first gap S1.

[0038] According to the above-described configuration, the cooling air can be supplied into the inner annular flow path 63 from the outside of the bearing housing 51 (casing 5) through the cooling air supply flow path 64, and can be supplied into the first gap S1 from the inside in the radial direction.

[0039] In some embodiments, as shown in FIG. 5, the cooling air supply flow path 64 includes an annular outer annular flow path 65 extending along the circumferential direction, a plurality of inner supply flow paths 66, and an outer supply flow path 67. The outer annular flow path 65 is formed outside the inner annular flow path 63 in the radial direction. One end of each of the plurality of inner supply flow paths 66 is connected to the inner annular flow path 63, the other end is connected to the outer annular flow path 65, and the inner supply flow paths 66 are disposed at an interval from each other in the circumferential direction. One end of the outer supply flow path 67 is connected to the outer annular flow path 65, and the supply side outer opening 641 is formed at the other end.

[0040] In the shown embodiment, each of the outer supply flow path 67 and the plurality of inner supply flow paths 66 extends along the radial direction. The cooling air flowing through the cooling air supply flow path 64 flows in the order of the outer supply flow path 67, the outer annular flow path 65, the inner supply flow path 66, and the inner annular flow path 63.

[0041] According to the above-described configuration, the cooling air can be supplied from each of the plurality of inner supply flow paths 66 to a plurality of locations of the inner annular flow path 63 in the circumferential direction. Therefore, cooling can be performed by the cooling air over a relatively wide range of the first gap S1 in the circumferential direction.Other Side Cooling Air Supply Line

[0042] In the centrifugal compressor 1 according to some embodiments, as shown in FIGS. 1 and 2, the other side cooling air supply line 62 includes an annular inner annular flow path 68 extending along the circumferential direction, and a cooling air supply flow path 69. The inner annular flow path 68 is formed inside the bearing housing 51 (casing 5), and is connected to the inside of the second gap S2 in the radial direction. The cooling air supply flow path 69 includes an supply side outer opening 691 formed on the outer surface 56 of the bearing housing 51 (casing 5), and an supply side inner opening 692 formed on the other side with respect to a connecting portion P2 of the inner annular flow path 68 with the second gap S2.

[0043] As shown in FIGS. 1 and 2, the centrifugal compressor 1 according to some embodiments further includes a rotor 81 of an electric motor 8 and a stator 82 of the electric motor 8. The rotor 81 includes a permanent magnet 83, and is attached to the other side with respect to the thrust disc portion 21 of the rotary shaft 2. The stator 82 includes a stationary coil portion 85, and is disposed on an outer peripheral side of the rotor 81 to face the rotor 81 with a third gap S3. An electric motor accommodation space 57A accommodating the rotor 81 and the stator 82 of the electric motor 8 is formed inside the bearing housing 51.

[0044] The rotor 81 further includes a permanent magnet support portion 84 supporting the permanent magnet 83. The permanent magnet support portion 84 is attached to the rotary shaft 2. The stator 82 further includes a stationary coil portion support portion 86 supporting the stationary coil portion 85. The stationary coil portion support portion 86 is supported by the bearing housing 51.

[0045] In the embodiment shown in FIGS. 1 and 2, the centrifugal compressor 1 includes an electric centrifugal compressor configured to rotate the rotary shaft 2 in such a manner that the electric motor 8 is driven by supplying electric power to the electric motor 8 from an electric power source (not shown). Some embodiments of the present disclosure are also applicable to the centrifugal compressor 1 that does not include the electric motor 8.

[0046] In the embodiment shown in FIGS. 1 and 2, the cooling air supply flow path 69 includes annular other side supply flow paths 693 and 694 extending along the circumferential direction, the electric motor accommodation space 57A, and a gap 104 formed between the one side journal bearing 101 and the rotary shaft 2. The gap 104 communicates with each of the electric motor accommodation space 57A and the inner annular flow path 68.

[0047] The other side supply flow path 693 is formed on the other side with respect to a gap 105 formed between the electric motor accommodation space 57A and the other side journal bearing 102 in the bearing housing 51 and the rotary shaft 2. The other side supply flow path 693 extends along the radial direction, one end of which has an supply side outer opening 691, and the other end of which is connected to a gap 106. The gap 106 is a gap formed between the rotary shaft 2 and the bearing housing 51 on the other side with respect to the gap 105 and on the one side with respect to the other side impeller 32, and communicates with the gap 105 adjacent to the one side. The other side supply flow path 694 extends along the axial direction, one end of which is connected to the other side supply flow path 693, and the other end of which is connected to the electric motor accommodation space 57A.

[0048] In some embodiments, as shown in FIGS. 1 and 2, a second air bleeding line 112 for supplying the compressed air flowing through the relay line 11 to the supply side outer opening 691 may be connected to the other side cooling air supply line 62. One end of the second air bleeding line 112 is connected to the relay line 11, and the other end is connected to the supply side outer opening 691. A portion of the compressed air flowing through the relay line 11 is bled into the other side cooling air supply line 62 via the second air bleeding line 112. In this embodiment, for example, at least a portion of the cooling air flowing through the other side cooling air supply line 62 flows in the order of the second air bleeding line 112, the other side supply flow paths 693 and 694, the electric motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. At least a portion of the cooling air flowing through the other side cooling air supply line 62 may flow in the order of the second air bleeding line 112, the other side supply flow path 693, the gap 106, the gap 105, the electric motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. In this embodiment, the cooling air can be supplied to the second gap S2 via the other side cooling air supply line 62 without providing a blower 107 (to be described later) in the centrifugal compressor 1. Therefore, a size increase of the centrifugal compressor 1 can be suppressed.

[0049] In some embodiments, as shown in FIGS. 1 and 2, the blower 107 for raising the pressure of the cooling air supplied into the supply side outer opening 691 may be connected to the other side cooling air supply line 62. In this embodiment, the cooling air is supplied from the blower 107 to the other side cooling air supply line 62.

[0050] According to the above-described configuration, the cooling air can be supplied into the inner annular flow path 68 from the outside of the bearing housing 51 (casing 5) through the cooling air supply flow path 69, and can be supplied into the second gap S2 from the inside in the radial direction.Cooling Air Exhaust LineFIG. 6 is a schematic view when a cooling air exhaust line 7 according to the embodiment of the present disclosure is viewed from the one side in the axial direction. As shown in FIGS. 1, 2, and 6, the centrifugal compressor 1 according to some embodiments further includes the cooling air exhaust line 7 for exhausting the cooling air to the outside of the bearing housing 51 (casing 5) from each of the first gap S1 and the second gap S2.

[0052] The cooling air exhaust line 7 includes an annular exhaust side annular flow path 71 extending along the circumferential direction, and a cooling air exhaust flow path 72. The exhaust side annular flow path 71 is formed inside the bearing housing 51 (casing 5), and is connected to the outside of the first gap S1 and the second gap S2 in the radial direction. The cooling air exhaust flow path 72 includes an exhaust side outer opening 721 formed on the outer surface 56 of the bearing housing 51 (casing 5), and an exhaust side inner opening 722 formed in the exhaust side annular flow path 71. The cooling air flows in the order of the exhaust side annular flow path 71 and the cooling air exhaust flow path 72 from each of the first gap S1 and the second gap S2, and thereafter, the cooling air is exhausted to the outside of the bearing housing 51. In the embodiment shown in FIG. 1, the cooling air exhaust flow path 72 extends along the radial direction.

[0053] According to the above-described configuration, the cooling air cooling the thrust bearing 4 after flowing through the gaps S1 and S2 can be exhausted to the outside of the casing 5 by the cooling air exhaust line 7. When the cooling air supply line 6 includes both the one side cooling air supply line 61 and the other side cooling air supply line 62, the cooling air is exhausted to the outside of the casing 5 through the common cooling air exhaust line 7 from the first gap S1 and the second gap S2. In this manner, a size increase of the casing 5 can be suppressed, and ultimately, a size increase of the centrifugal compressor 1 can be suppressed.

[0054] In some embodiments, as shown in FIG. 2, the cooling air exhaust flow path 72 includes an internal space 57 formed inside the bearing housing 51 (casing 5) and having a volume larger than a volume of the exhaust side annular flow path 71.

[0055] According to the above-described configuration, the internal space 57 having the volume larger than the volume of the exhaust side annular flow path 71 is provided in the cooling air exhaust flow path 72. In this manner, the formation of a circulation flow, that is, an inward flow of the cooling air from the outside inside the thrust bearing 4 in the radial direction, can be suppressed in the thrust bearing 4, which is an air bearing. Therefore, the flow of the cooling air from the exhaust side annular flow path 71 to the internal space 57 is promoted. In addition, since formation of the circulation flow in the thrust bearing 4 is suppressed, collision of the circulation flow with the cooling air supplied to the gaps S1 and S2 can be suppressed. Therefore, the supply of the cooling air to the gaps S1 and S2 is promoted.

[0056] In some embodiments, as shown in FIG. 2, the internal space 57, which is a portion of the cooling air exhaust flow path 72, includes the electric motor accommodation space 57A. In the embodiment shown in FIG. 2, the cooling air exhaust flow path 72 includes a communication flow path 72A, one end of which is connected to the exhaust side annular flow path 71 and the other end of which is connected to the electric motor accommodation space 57A at a position in the radial direction outside the exhaust side annular flow path 71 and the stationary coil portion 85 in the radial direction.

[0057] According to the above-described configuration, since the electric motor accommodation space 57A is used as the internal space 57 provided in the cooling air exhaust flow path 72, the internal space 57 does not need to be separately formed inside the casing 5. Therefore, a size increase of the casing 5 can be suppressed, and ultimately, a size increase of the centrifugal compressor 1 can be suppressed.Shielding Portion

[0058] Each of FIGS. 7 and 8 is a schematic cross-sectional view taken along the axial direction in the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to the embodiment of the present disclosure. In some embodiments, as shown in FIGS. 7 and 8, the one side thrust bearing 41 includes at least one through-hole 43 (in the shown example, a plurality of through-holes 43) penetrating along the radial direction. The centrifugal compressor 1 further includes a shielding portion 9 covering an outer peripheral side (outside in the radial direction) of the plurality of through-holes 43 and inhibiting the inflow of the gas into the plurality of through-holes 43.

[0059] As shown in FIG. 4, the through-hole 43 may be formed between the top foil 412 and the elastic foil 413, or may be formed between the elastic foil 413 and the support plate 414. It is preferable that a gap between the shielding portion 9 and the one side thrust bearing 41 is small. As shown in FIG. 7, the shielding portion 9 may be attached to the one side thrust bearing support portion 54, or may be formed integrally with the one side thrust bearing support portion 54. In addition, the shielding portion 9 may be formed integrally with the one side thrust bearing 41. The shielding portion 9 may be attached to the one side thrust bearing 41. In the embodiment shown in FIG. 8, the shielding portion 9 is formed by bending an outer peripheral end portion of the support plate 414.

[0060] In some embodiments, as shown in FIGS. 7 and 8, the other side thrust bearing 42 includes at least one through-hole 43A (in the shown example, a plurality of through-holes 43A) penetrating along the radial direction. The centrifugal compressor 1 further includes a shielding portion 9A covering an outer peripheral side (outside in the radial direction) of the plurality of through-holes 43A and inhibiting the inflow of the gas into the plurality of through-holes 43A.

[0061] As shown in FIG. 4, the through-hole 43A may be formed between the top foil 422 and the elastic foil 423, or may be formed between the elastic foil 423 and the support plate 424. It is preferable that a gap between the shielding portion 9A and the other side thrust bearing 42 is small. As shown in FIG. 7, the shielding portion 9A may be attached to the other side thrust bearing support portion 55, or may be formed integrally with the other side thrust bearing support portion 55. In addition, the shielding portion 9A may be formed integrally with the other side thrust bearing 42. The shielding portion 9A may be attached to the other side thrust bearing 42. In the embodiment shown in FIG. 8, the shielding portion 9A is formed by bending an outer peripheral end portion of the support plate 424.

[0062] According to the above-described configuration, since the shielding portions 9 and 9A are provided, the inflow of the cooling air into the through-holes 43 and 43A of the thrust bearing 4 can be inhibited. Therefore, the formation of the circulation flow, that is, the inward flow of the cooling air from the outside in the radial direction through the through-holes 43 and 43A of the thrust bearing 4, can be suppressed in the thrust bearing 4. In this manner, exhausting the cooling air from the exhaust side annular flow path 71 is promoted. In addition, since formation of the circulation flow in the thrust bearing 4 is suppressed, collision of the circulation flow with the cooling air supplied to the gaps S1 and S2 can be suppressed. Therefore, the supply of the cooling air to the gaps S1 and S2 is promoted.

[0063] In the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.

[0064] For example, expressions representing that things are in an equal state such as “same”, “equal”, and “homogeneous” not only strictly represent an equal state, but also represent a state where a difference exists with a tolerance or to such an extent that the same function can be obtained.

[0065] In addition, in the present specification, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

[0066] In addition, in the present specification, expressions such as “being provided with”, “including”, and “having” one component are not exclusive expressions excluding the presence of other components.

[0067] The present disclosure is not limited to the above-described embodiments, and also includes a form in which modifications are added to the above-described embodiments or a form in which the embodiments are combined with each other as appropriate.

[0068] Contents described in some embodiments described above are understood as follows, for example.

[0069] 1) The centrifugal compressor (1) according to at least one embodiment of the present disclosure includes the rotary shaft (2), at least one compressor impeller (3) attached to at least one of one side and the other side of the rotary shaft (2), the thrust disc portion (21) provided in the rotary shaft (2) and extending along the radial direction of the rotary shaft (2), at least one thrust bearing (4), which is an air bearing, which is disposed on the one side or the other side of the rotary shaft (2) with respect to the thrust disc portion (21), and which faces the thrust disc portion (21) with the gaps (S1 and S2), the casing (5) accommodating the rotary shaft (2) and the thrust disc portion (21) to be rotatable and supporting the at least one thrust bearing (4), and at least one cooling air supply line (6) configured to supply the cooling air from the outside of the casing (5) into the gaps (S1 and S2) from the inside in the radial direction.

[0070] According to the configuration of 1) above, the cooling air present in the gaps (S1 and S2) is pushed out (pumped up) from the inside to the outside in the radial direction as the rotary shaft (2) rotates. Since the cooling air is pumped up, the supply of the cooling air from the cooling air supply line (6) to the gaps (S1 and S2) and the movement of the cooling air present in the gaps (S1 and S2) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the gaps (S1 and S2). This centrifugal compressor (1) can effectively cool the thrust bearing (4), which is an air bearing.

[0071] 2) In some embodiments, in the centrifugal compressor (1) according to 1), the at least one compressor impeller (3) includes the one side impeller (31) attached to the one side of the rotary shaft (2), the at least one thrust bearing (4) includes the one side thrust bearing (41) disposed on the one side of the rotary shaft (2) with respect to the thrust disc portion (21) and facing the thrust disc portion (21) with the first gap (S1), and the at least one cooling air supply line (6) includes the one side cooling air supply line (61) configured to supply the cooling air from the outside of the casing (5) into the first gap (S1) from the inside in the radial direction.

[0072] According to the configuration of 2) above, since the cooling air is pumped up, the supply of the cooling air from the one side cooling air supply line (61) to the first gap (S1) and the movement of the cooling air present in the first gap (S1) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the first gap (S1).

[0073] 3) In some embodiments, in the centrifugal compressor (1) according to 1) or 2), the at least one compressor impeller (3) includes the other side impeller (32) attached to the other side of the rotary shaft (2), the at least one thrust bearing (4) includes the other side thrust bearing (42) disposed on the one side of the rotary shaft (2) with respect to the thrust disc portion (21) and facing the thrust disc portion (21) with the second gap (S2), and the at least one cooling air supply line (6) includes the other side cooling air supply line (62) configured to supply the cooling air from the outside of the casing (5) into the second gap (S2) from the inside in the radial direction.

[0074] According to the configuration of 3) above, since the cooling air is pumped up, the supply of the cooling air from the other side cooling air supply line (62) to the second gap (S2) and the movement of the cooling air present in the second gap (S2) to the outside in the radial direction are promoted. Therefore, the required amount of the cooling air is easily supplied to the second gap (S2). When the cooling air supply line (6) includes both the one side cooling air supply line (61) and the other side cooling air supply line (62), the one side cooling air supply line (61) and the other side cooling air supply line (62) are set as separate lines. In this manner, the amount of the cooling air fed to the first gap (S1) and the second gap (S2) is easily secured. In addition, since the cooling air is supplied to both the first gap (S1) and the second gap (S2) via the one side cooling air supply line (61) and the other side cooling air supply line (62), the thrust bearing (4) can be more effectively cooled.

[0075] 4) In some embodiments, in the centrifugal compressor (1) according to 2), the one side cooling air supply line (61) includes the annular inner annular flow path (63) formed inside the casing (5) and connected to the inside of the first gap (S1) in the radial direction, and the cooling air supply flow path (64) including the supply side outer opening (641) formed on the outer surface (56) of the casing (5), and the supply side inner opening (642) formed on the one side with respect to the connecting portion of the inner annular flow path (63) with the first gap (S1).

[0076] According to the configuration of 4) above, the cooling air can be supplied into the inner annular flow path (63) from the outside of the casing (5) through the cooling air supply flow path (64), and can be supplied into the first gap (S1) from the inside in the radial direction.

[0077] 5) In some embodiments, in the centrifugal compressor (1) according to 4), the cooling air supply flow path (64) includes the outer annular flow path (65) formed outside the inner annular flow path (63) in the radial direction, the plurality of inner supply flow paths (66) in which one end is connected to the inner annular flow path (63) and the other end is connected to the outer annular flow path (65), the plurality of inner supply flow paths (66) being disposed at an interval from each other in the circumferential direction of the rotary shaft (2), and the outer supply flow path (67) in which one end is connected to the outer annular flow path (65) and the supply side outer opening (641) is formed at the other end.

[0078] According to the configuration of 5) above, the cooling air can be supplied from each of the plurality of inner supply flow paths (66) to the plurality of locations of the inner annular flow path (63) in the circumferential direction. Therefore, cooling can be performed by the cooling air over a relatively wide range of the first gap (S1) in the circumferential direction.

[0079] 6) In some embodiments, the centrifugal compressor (1) according to any one of 1) to 5) further includes the cooling air exhaust line (7) for exhausting the cooling air to the outside of the casing (5) from the gaps (S1 and S2). The cooling air exhaust line (7) includes the annular exhaust side annular flow path (71) formed inside the casing (5) and connected to the outside of the gaps (S1 and S2) in the radial direction, and the cooling air exhaust flow path (72) including the exhaust side outer opening (721) formed on the outer surface (56) of the casing (5), and the exhaust side inner opening (722) formed in the exhaust side annular flow path (71).

[0080] According to the configuration of 6) above, the cooling air cooling the thrust bearing (4) after flowing through the gaps (S1 and S2) can be exhausted to the outside of the casing (5) by the cooling air exhaust line (7). When the cooling air supply line (6) includes both the one side cooling air supply line (61) and the other side cooling air supply line (62), the cooling air is exhausted to the outside of the casing (5) through the common cooling air exhaust line (7) from the first gap (S1) and the second gap (S2). In this manner, a size increase of the casing (5) can be suppressed, and ultimately, a size increase of the centrifugal compressor (1) can be suppressed.

[0081] 7) In some embodiments, in the centrifugal compressor (1) according to 6), the cooling air exhaust flow path (72) includes the internal space (57) formed inside the casing (5) and having the volume larger than the volume of the exhaust side annular flow path (71).

[0082] According to the configuration of 7) above, the internal space (57) having the volume larger than the volume of the exhaust side annular flow path (71) is provided in the cooling air exhaust flow path (72). In this manner, formation of the circulation flow in the thrust bearing (4), which is an air bearing, can be suppressed. Therefore, the flow of the cooling air from the exhaust side annular flow path (71) to the internal space (57) is promoted. In addition, since formation of the circulation flow in the thrust bearing (4) is suppressed, collision of the circulation flow with the cooling air supplied to the gaps (S1 and S2) can be suppressed. Therefore, the supply of the cooling air to the gaps (S1 and S2) is promoted.

[0083] 8) In some embodiments, the centrifugal compressor (1) according to 7) further includes the rotor (81) of the electric motor (8) including the permanent magnet (83) and attached to the other side of the rotary shaft (2) with respect to the thrust disc portion (21), and the stator (82) of the electric motor (8) including the stationary coil portion (85) and disposed on the outer peripheral side of the rotor (81) to face the rotor (81) with the third gap (S3). The internal space (57) includes the electric motor accommodation space (57A) accommodating the rotor (81) and the stator (82) of the electric motor (8).

[0084] According to the configuration of 8) above, the electric motor accommodation space (57A) is used as the internal space (57) provided in the cooling air exhaust flow path (72). In this manner, the internal space (57) does not need to be separately formed inside the casing (5). Therefore, a size increase of the casing (5) can be suppressed, and ultimately, a size increase of the centrifugal compressor (1) can be suppressed.

[0085] 9) In some embodiments, in the centrifugal compressor (1) according to any one of 1) to 8), the at least one thrust bearing (4) includes at least one through-hole (43 and 43A) penetrating along the radial direction, and the centrifugal compressor (1) further includes the shielding portion (9) covering the outer peripheral side of the at least one through-hole (43 and 43A) and inhibiting the inflow of the gas into the at least one through-hole (43 and 43A).

[0086] According to the configuration of 9) above, since the shielding portion (9) is provided, the inflow of the cooling air into the through-holes (43 and 43A) of the thrust bearing (4) can be inhibited. Therefore, formation of the circulation flow in the thrust bearing (4) can be suppressed. In this manner, exhausting the cooling air from the exhaust side annular flow path (71) is promoted. In addition, since formation of the circulation flow in the thrust bearing (4) is suppressed, collision of the circulation flow with the cooling air supplied to the gaps (S1 and S2) can be suppressed. Therefore, the supply of the cooling air to the gaps (S1 and S2) is promoted.REFERENCE SIGNS LIST1: centrifugal compressor

[0088] 2: rotary shaft

[0089] 3: compressor impeller

[0090] 4: thrust bearing

[0091] 5: casing

[0092] 6: cooling air supply line

[0093] 7: cooling air exhaust line

[0094] 8: electric motor

[0095] 9, 9A: shielding portion

[0096] 11: relay line

[0097] 12: fuel cell

[0098] 13: compressed air supply line

[0099] 21: thrust disc portion

[0100] 31: one side impeller

[0101] 32: other side impeller

[0102] 41: one side thrust bearing

[0103] 42: other side thrust bearing

[0104] 43, 43A: through-hole

[0105] 51: bearing housing

[0106] 52: one side housing

[0107] 53: other side housing

[0108] 54: one side thrust bearing support portion

[0109] 55: other side thrust bearing support portion

[0110] 56: outer surface

[0111] 57: internal space

[0112] 57A: electric motor accommodation space

[0113] 61: one side cooling air supply line

[0114] 62: other side cooling air supply line

[0115] 63, 68: inner annular flow path

[0116] 64, 69: cooling air supply flow path

[0117] 65: outer annular flow path

[0118] 66: inner supply flow path

[0119] 67: outer supply flow path

[0120] 71: exhaust side annular flow path

[0121] 72: cooling air exhaust flow path

[0122] 81: rotor

[0123] 82: stator

[0124] 83: permanent magnet

[0125] 84: permanent magnet support portion

[0126] 85: stationary coil portion

[0127] 86: stationary coil portion support portion

[0128] 101, 102: journal bearing

[0129] 103, 107: blower

[0130] 104, 105, 106: gap

[0131] 111: first air bleeding line

[0132] 112: second air bleeding line

[0133] 412, 422: top foil

[0134] 413, 423: elastic foil

[0135] 414, 424: support plate

[0136] 641, 691: supply side outer opening

[0137] 642, 692: supply side inner opening

[0138] 721: exhaust side outer opening

[0139] 722: exhaust side inner opening

[0140] CA: central axis

[0141] P1, P2: connecting portion

[0142] S1: first gap

[0143] S2: second gap

[0144] S3: third gap

Examples

Embodiment Construction

[0016]Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, dimensions, materials, shapes, and relative dispositions of components described as the embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, and are merely examples for describing the present disclosure.

Centrifugal Compressor

[0017]Each of FIGS. 1 and 2 is a schematic cross-sectional view taken along an axial direction of a centrifugal compressor 1 according to an embodiment of the present disclosure. The centrifugal compressor 1 according to some embodiments includes a rotary shaft 2, at least one compressor impeller 3 attached to at least one of one side and the other side of the rotary shaft 2 in the axial direction, a thrust disc portion 21 provided in the rotary shaft 2 and extending along a radial direction of the rotary shaft 2, at least one thrust bearing 4, which is an air bearing, which is dispos...

Claims

1. A centrifugal compressor comprising:a rotary shaft;at least one compressor impeller attached to at least one of one side and the other side of the rotary shaft;a thrust disc portion provided in the rotary shaft and extending along a radial direction of the rotary shaft;at least one thrust bearing, which is an air bearing, which is disposed on the one side or the other side of the rotary shaft with respect to the thrust disc portion, and which faces the thrust disc portion with a gap;a casing accommodating the rotary shaft and the thrust disc portion to be rotatable and supporting the at least one thrust bearing; andat least one cooling air supply line configured to supply cooling air from an outside of the casing into the gap from an inside in the radial direction.

2. The centrifugal compressor according to claim 1,wherein the at least one compressor impeller includes a one side impeller attached to the one side of the rotary shaft,the at least one thrust bearing includes a one side thrust bearing disposed on the one side of the rotary shaft with respect to the thrust disc portion and facing the thrust disc portion with a first gap, andthe at least one cooling air supply line includes a one side cooling air supply line configured to supply the cooling air from the outside of the casing into the first gap from the inside in the radial direction.

3. The centrifugal compressor according to claim 1,wherein the at least one compressor impeller includes the other side impeller attached to the other side of the rotary shaft,the at least one thrust bearing includes the other side thrust bearing disposed on the one side of the rotary shaft with respect to the thrust disc portion and facing the thrust disc portion with a second gap, andthe at least one cooling air supply line includes the other side cooling air supply line configured to supply the cooling air from the outside of the casing into the second gap from the inside in the radial direction.

4. The centrifugal compressor according to claim 2,wherein the one side cooling air supply line includesan annular inner annular flow path formed inside the casing and connected to an inside of the first gap in the radial direction, anda cooling air supply flow path including an supply side outer opening formed on an outer surface of the casing, and an supply side inner opening formed on the one side with respect to a connecting portion of the inner annular flow path with the first gap.

5. The centrifugal compressor according to claim 4,wherein the cooling air supply flow path includesan outer annular flow path formed outside the inner annular flow path in the radial direction,a plurality of inner supply flow paths in which one end is connected to the inner annular flow path and the other end is connected to the outer annular flow path, the plurality of inner supply flow paths being disposed at an interval from each other in a circumferential direction of the rotary shaft, andan outer supply flow path in which one end is connected to the outer annular flow path and the supply side outer opening is formed at the other end.

6. The centrifugal compressor according to claim 1, further comprising:a cooling air exhaust line for exhausting the cooling air to the outside of the casing from the gap,wherein the cooling air exhaust line includesan annular exhaust side annular flow path formed inside the casing and connected to an outside of the gap in the radial direction, anda cooling air exhaust flow path including an exhaust side outer opening formed on an outer surface of the casing, and an exhaust side inner opening formed in the exhaust side annular flow path.

7. The centrifugal compressor according to claim 6,wherein the cooling air exhaust flow path includes an internal space formed inside the casing and having a volume larger than a volume of the exhaust side annular flow path.

8. The centrifugal compressor according to claim 7, further comprising:a rotor of an electric motor including a permanent magnet and attached to the other side of the rotary shaft with respect to the thrust disc portion; anda stator of the electric motor including a stationary coil portion and disposed on an outer peripheral side of the rotor to face the rotor with a third gap,wherein the internal space includes an electric motor accommodation space accommodating the rotor and the stator of the electric motor.

9. The centrifugal compressor according to claim 1,wherein the at least one thrust bearing includes at least one through-hole penetrating along the radial direction, andthe centrifugal compressor further comprises a shielding portion covering an outer peripheral side of the at least one through-hole and inhibiting an inflow of a gas into the at least one through-hole.

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