Centrifugal compressor

Abstract

A 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; the thrust disc part is arranged on the rotating shaft and extends in the 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 part, and faces the thrust disc part with a gap therebetween; a housing which rotatably accommodates the rotating shaft and the thrust disc part and supports the at least one thrust bearing; and at least one cooling air introduction line configured so as to introduce cooling air from the outside of the housing to the gap from the inside in the radial direction.

Description

Technical Field

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

[0002] To improve fuel cell efficiency, a compressor compresses the air supplied to the cathode side of the fuel cell (see Patent Document 1). Patent Document 1 discloses a two-stage compressor with a low-pressure compressor impeller and a high-pressure compressor impeller mounted on a common shaft, driven by an electric motor. In this two-stage compressor, the compressed air from the low-pressure compressor impeller is further compressed by the high-pressure compressor impeller. The compressed air from the high-pressure compressor impeller is then delivered to the fuel cell to promote the fuel cell reaction.

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-187444 Summary of the Invention

[0006] Technical issues to be solved by the invention

[0007] To prevent fuel oil from mixing into fuel cells, air bearings are sometimes used as bearings for the shafts of compressors that supply compressed air to fuel cells. Patent Document 1 describes a method of supplying cooling air to a thrust bearing, which serves as an air bearing, from the radially outer side. The cooling air in the gap formed between the thrust bearing, which serves as a stationary body, and a rotating shaft, or thrust plate, which is spaced apart from the thrust bearing and rotates with the shaft, is pushed (drawn) from the radially inner side to the outer side as the shaft rotates. Therefore, when cooling air is supplied to the thrust bearing, which serves as an air bearing, from the radially outer side, it becomes difficult to supply cooling air to the thrust bearing, which may result in insufficient cooling of the thrust bearing.

[0008] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a centrifugal compressor capable of effectively cooling a thrust bearing serving as an air bearing.

[0009] Means for solving technical problems

[0010] A centrifugal compressor according to at least one embodiment of the present invention includes:

[0011] Rotation axis;

[0012] at least one compressor impeller mounted on at least one of one side or the other side of the rotating shaft;

[0013] a thrust disc portion, disposed on the rotating shaft and extending along the radial direction of the rotating shaft;

[0014] at least one thrust bearing, which is an air bearing, is disposed on the one side or the other side of the rotation axis relative to the thrust plate portion and faces the thrust plate portion with a gap therebetween;

[0015] a housing rotatably accommodating the rotating shaft and the thrust disc portion and supporting the at least one thrust bearing; and

[0016] At least one cooling air introduction duct is configured to introduce cooling air from the outside of the housing into the gap from the inside in the radial direction.

[0017] Effects of the Invention

[0018] According to at least one embodiment of the present invention, a centrifugal compressor capable of effectively cooling a thrust bearing serving as an air bearing is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic cross-sectional view along the axial direction of a centrifugal compressor according to one embodiment of the present invention.

[0020] Figure 2 It is a schematic cross-sectional view along the axial direction of a centrifugal compressor according to one embodiment of the present invention.

[0021] Figure 3 It is a schematic cross-sectional view taken along the axial direction and near a thrust bearing of a centrifugal compressor according to one embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram showing the vicinity of a thrust bearing of a centrifugal compressor according to an embodiment of the present invention as viewed from the outside in the radial direction.

[0023] Figure 5 This is a schematic diagram of a cooling air inlet pipe on one side in one embodiment of the present invention as viewed from one side in the axial direction.

[0024] Figure 6 This is a schematic diagram of a cooling air exhaust pipeline in one embodiment of the present invention as viewed from one side in the axial direction.

[0025] Figure 7 It is a schematic cross-sectional view taken along the axial direction and near a thrust bearing of a centrifugal compressor according to one embodiment of the present invention.

[0026] Figure 8 It is a schematic cross-sectional view taken along the axial direction and near a thrust bearing of a centrifugal compressor according to one embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

[0028] (Centrifugal compressor)

[0029] Figure 1 and Figure 2 Each of the figures is a schematic cross-sectional view of a centrifugal compressor 1 according to an embodiment of the present invention, taken along the axial direction. The centrifugal compressor 1 according to some embodiments comprises: a rotating shaft 2; at least one compressor impeller 3 mounted on at least one of one or the other axial sides of the rotating shaft 2; a thrust plate portion 21 disposed on the rotating shaft 2 and extending radially in the rotating shaft 2; at least one thrust bearing 4, which is an air bearing, disposed on one or the other side of the rotating shaft 2 relative to the thrust plate portion 21 and opposed to the thrust plate portion 21 with gaps S1 and S2 therebetween; and a housing 5 rotatably accommodating the rotating shaft 2 and the thrust plate portion 21 and supporting the at least one thrust bearing 4.

[0030] Hereinafter, the direction in which the central axis CA of the rotating shaft 2 extends is defined as the axial direction of the rotating shaft 2, the direction orthogonal to the central axis CA is defined as the radial direction of the rotating shaft 2, and the circumferential direction around the central axis CA is defined as the circumferential direction of the rotating shaft 2. In the present invention, the axial, radial, and circumferential directions of the rotating shaft 2 are sometimes referred to simply as the axial direction, radial direction, and circumferential direction, respectively. The term "along a certain direction" in the present invention encompasses not only a certain direction but also a direction inclined within a range of ±15° relative to a certain direction.

[0031] (Thrust plate)

[0032] The thrust plate portion 21 may be formed integrally with the rotating shaft 2 or may be a separate body from the rotating shaft 2 , and may be mounted on the rotating shaft 2 by being fitted, for example.

[0033] (Compressor impeller)

[0034] exist Figure 1 and Figure 2In the illustrated embodiment, the at least one compressor impeller 3 includes a one-side impeller 31 and an other-side impeller 32. The one-side impeller 31 is mounted on one axial side of the rotating shaft 2 (the right side in the figure). The other-side impeller 32 is mounted on the other axial side of the rotating shaft 2 (the left side in the figure). In the illustrated embodiment, the one-side impeller 31 and the other-side impeller 32 are composed of centrifugal impellers configured to guide the air guided along the above-mentioned axial direction to the above-mentioned radial outer side. Hereinafter, the one side and the other side of the axial direction of the rotating shaft 2 are sometimes referred to as simply one side and the other side, respectively. In addition, some embodiments of the present invention can also be applied to a centrifugal compressor 1 that only has one of the one-side impeller 31 or the other-side impeller 32.

[0035] exist Figure 1 and Figure 2 In the illustrated embodiment, one impeller 31 is a low-pressure compressor impeller, and the other impeller 32 is a high-pressure compressor impeller. The centrifugal compressor 1 may further include a relay line 11 for guiding compressed air compressed by the one impeller 31 to the other impeller 32. The centrifugal compressor 1 may further include a compressed air introduction line 13 for supplying compressed air compressed by the other impeller 32 to the cathode side of the fuel cell 12.

[0036] (Thrust bearing)

[0037] exist Figure 1 and Figure 2 In the illustrated embodiment, the at least one thrust bearing 4 includes a one-side thrust bearing 41 and a second-side thrust bearing 42. The one-side thrust bearing 41 is an air bearing and is disposed on the one side of the thrust plate portion 21 and faces the thrust plate portion 21 with a first gap S1 therebetween. The second-side thrust bearing 42 is an air bearing and is disposed on the other side of the thrust plate portion 21 and faces the thrust plate portion 21 with a second gap S2 therebetween.

[0038] (shell)

[0039] exist Figure 1 and Figure 2 In the illustrated embodiment, the housing 5 includes a bearing housing 51 that rotatably accommodates the rotating shaft 2 and the thrust disk portion 21 and supports the one-side thrust bearing 41 and the other-side thrust bearing 42. The housing 5 may further include a one-side housing 52 disposed on the one side of the bearing housing 51 and an other-side housing 53 disposed on the other side of the bearing housing 51. The one-side housing 52 is secured 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 secured to the bearing housing 51 and accommodates the other-side impeller 32 between the one-side housing 52 and the bearing housing 51.

[0040] (Journal bearings)

[0041] exist Figure 1 and Figure 2 In the illustrated embodiment, the centrifugal compressor 1 further includes a first-side journal bearing 101 that rotatably supports the first side of the rotating shaft 2, and a second-side journal bearing 102 that rotatably supports the second side of the rotating shaft 2. The first-side journal bearing 101 and the second-side journal bearing 102 are each air bearings housed in and supported by the bearing housing 51. In the illustrated embodiment, the first-side journal bearing 101 is positioned closer to the second side than the thrust plate portion 21. The second-side journal bearing 102 is positioned closer to the second side than the first-side journal bearing 101 and closer to the second side than the second-side impeller 32.

[0042] (Cooling air inlet pipe)

[0043] like Figure 1 and Figure 2 As shown, some embodiments of the centrifugal compressor 1 include at least one cooling air introduction pipe 6 configured to introduce cooling air from the outside of the casing 5 into the first gap S1 or the second gap S2 from the radially inner side. "Cooling air" can be any air that can cool the thrust bearing 4 by flowing through the first gap S1 or the second gap S2. For example, it can be air at room temperature (between 0°C and 40°C). Cooling air is introduced from the radially inner side into at least one of the first gap S1 or the second gap S2 via the cooling air introduction pipe 6.

[0044] With the above configuration, the cooling air in gaps S1 and S2 is pushed (drawn) radially outward as the rotating shaft 2 rotates. This suction facilitates the supply of cooling air from the cooling air inlet pipe 6 to the gaps S1 and S2 and the radial outward movement of the cooling air in gaps S1 and S2, thus facilitating the supply of the required amount of cooling air to the gaps S1 and S2. This centrifugal compressor 1 can effectively cool the thrust bearing 4, which serves as an air bearing.

[0045] (1st gap, 2nd gap)

[0046] Figure 3 It is a schematic cross-sectional view in the axial direction and the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to one embodiment of the present invention. Figure 4 This is a schematic diagram of the vicinity of the thrust bearing 4 of the centrifugal compressor 1 according to one embodiment of the present invention as viewed from the outside in the radial direction. Figure 3 and Figure 4As shown, a first gap S1 is formed between the one end surface 22 of the thrust plate portion 21 and the other end surface 411 of the thrust bearing 41 on the one side, which faces the end surface 22. A second gap S2 is formed between the other end surface 23 of the thrust plate portion 21 and the one end surface 421 of the thrust bearing 42 on the other side, which faces the end surface 23.

[0047] (Thrust bearing on one side, thrust bearing on the other side)

[0048] exist Figure 4 In the embodiment shown, the thrust bearing 41 on one side includes: a top foil 412, which is a thin metal plate having the end surface 411; and an elastic foil 413, which is arranged closer to the end surface than the top foil 412 and has the flexibility to elastically deform when the top foil 412 is subjected to a thrust load. The elastic foil 413 can be a convex foil having a corrugated plate shape (see Figure 4 ), or it can be a mesh foil with a mesh shape. Figure 4 In the illustrated embodiment, the one-side thrust bearing 41 can be arranged closer to the above-mentioned side than the elastic foil 413, and further includes a flat support plate 414 that supports the elastic foil 413. The housing 5 includes a one-side thrust bearing support portion 54 that supports the support plate 414 of the one-side thrust bearing 41.

[0049] exist Figure 4 In the embodiment shown, the other side thrust bearing 42 includes: a top foil 422, which is a thin metal plate having the above-mentioned end surface 421; and an elastic foil 423, which is arranged closer to the other side than the top foil 422 and is flexible enough to elastically deform when the top foil 422 is subjected to a thrust load. The elastic foil 423 can be a convex foil with a corrugated plate shape (see Figure 4 ), or it can be a mesh foil with a mesh shape. Figure 4 In the embodiment shown, the other side thrust bearing 42 may include a flat support plate 424 that is arranged closer to the other side than the elastic foil 423 and supports the elastic foil 423. The housing 5 includes a other side thrust bearing support portion 55 that supports the support plate 424 of the other side thrust bearing 42. In addition, the one side thrust bearing 41 and the other side thrust bearing 42 are not limited to Figure 4 The embodiment shown.

[0050] like Figure 1 and Figure 2 As shown, in the centrifugal compressor 1 according to some embodiments, the at least one cooling air introduction pipe 6 includes a side cooling air introduction pipe 61 configured to introduce cooling air from the outside of the casing 5 into the first gap S1 from the radially inner side.

[0051] With this configuration, the supply of cooling air from the cooling air inlet duct 61 to the first gap S1 and the radially outward movement of the cooling air in the first gap S1 are facilitated by suction, thereby facilitating the supply of a required amount of cooling air to the first gap S1. The cooling air flowing from the radially inner side to the outer side through the first gap S1 cools the thrust bearing 41 on the one side.

[0052] like Figure 1 and Figure 2 As shown, in the centrifugal compressor 1 according to some embodiments, the at least one cooling air introduction pipe 6 includes another cooling air introduction pipe 62 configured to introduce cooling air from the outside of the casing 5 into the second gap S2 from the radially inner side.

[0053] With this configuration, the supply of cooling air from the other-side cooling air introduction duct 62 to the second gap S2 and the radially outward movement of the cooling air in the second gap S2 are facilitated by suction, thereby facilitating the supply of a required amount of cooling air to the second gap S2. The cooling air flowing from the radially inner side to the outer side through the second gap S2 cools the other-side thrust bearing 42.

[0054] Furthermore, when the cooling air introduction duct 6 includes both the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, by providing the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62 as separate ducts, it is easier to ensure the amount of cooling air supplied to the first gap S1 and the second gap S2. Furthermore, by supplying cooling air to both the first gap S1 and the second gap S2 via the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, the thrust bearing 4 can be cooled more effectively.

[0055] Figure 5 This is a schematic diagram of a cooling air inlet pipe 61 in one embodiment of the present invention viewed from one axial side. Figure 1 、 Figure 2 and Figure 5 As shown, in some embodiments of the centrifugal compressor 1 , the cooling air inlet conduit 61 includes an inner annular flow path 63 extending in the circumferential direction and a cooling air inlet flow path 64. The inner annular flow path 63 is formed inside the bearing housing 51 (housing 5 ) and connects to the radially inner side of the first gap S1 . The cooling air inlet flow path 64 includes an inlet-side outer opening 641 formed on the outer surface 56 of the bearing housing 51 (housing 5 ) and an inlet-side inner opening 642 formed closer to the connection point P1 between the inner annular flow path 63 and the first gap S1 .

[0056] like Figure 1 and Figure 2 As shown, in some embodiments, the cooling air inlet line 61 may be connected to a first air extraction line 111 for introducing compressed air flowing through the relay line 11 into the inlet-side outer opening 641. One end of the first air extraction line 111 is connected to the relay line 11, and the other end is connected to the inlet-side outer opening 641. A portion of the compressed air flowing through the relay line 11 is extracted into the cooling air inlet line 61 via the first air extraction line 111. In this embodiment, the cooling air flowing through the cooling air inlet line 61 sequentially passes through the first air extraction line 111, the cooling air inlet flow path 64, the inner annular flow path 63, and the first gap S1. In this embodiment, even without the blower 103 (described later) in the centrifugal compressor 1, cooling air can be supplied to the first gap S1 via the cooling air inlet line 61, thereby preventing the centrifugal compressor 1 from increasing in size.

[0057] like Figure 1 and Figure 2 As shown, in some embodiments, the cooling air inlet pipe 61 may be connected to a blower 103 for increasing the pressure of the cooling air introduced into the inlet-side outer opening 641. In this embodiment, the cooling air flowing through the cooling air inlet pipe 61 sequentially passes through the blower 103, the cooling air inlet flow path 64, the inner annular flow path 63, and the first gap S1.

[0058] According to the above configuration, cooling air can be introduced from outside the bearing housing 51 (casing 5 ) into the inner annular flow path 63 through the cooling air introduction flow path 64 , and can also be introduced into the first gap S1 from the radially inner side.

[0059] like Figure 5 As shown, in some embodiments, the cooling air inlet 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 radially outward of the inner annular flow path 63. Each of the plurality of inner supply flow paths 66 has one end connected to the inner annular flow path 63 and the other end connected to the outer annular flow path 65, and is arranged spaced apart from each other in the circumferential direction. The outer supply flow path 67 has one end connected to the outer annular flow path 65 and the other end formed with an inlet-side outer opening 641.

[0060] In the illustrated embodiment, the outer supply flow path 67 and the plurality of inner supply flow paths 66 extend in the aforementioned radial direction. The cooling air flowing through the cooling air introduction flow path 64 flows sequentially through 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.

[0061] According to the above configuration, cooling air can be introduced from each of the plurality of inner supply flow paths 66 to a plurality of locations in the circumferential direction of the inner annular flow path 63 , thereby enabling cooling by cooling air over a relatively wide range in the circumferential direction of the first gap S1 .

[0062] (Cooling air inlet pipe on the other side)

[0063] like Figure 1 and Figure 2 As shown, in some embodiments of the centrifugal compressor 1 , the other-side cooling air introduction conduit 62 includes an inner annular flow path 68 extending in the circumferential direction and a cooling air introduction flow path 69. The inner annular flow path 68 is formed inside the bearing housing 51 (housing 5) and connects to the radially inner side of the second gap S2. The cooling air introduction flow path 69 includes an introduction-side outer opening 691 formed on the outer surface 56 of the bearing housing 51 (housing 5) and an introduction-side inner opening 692 formed on the other side of the connection point P2 between the inner annular flow path 68 and the second gap S2.

[0064] like Figure 1 and Figure 2 As shown, the centrifugal compressor 1 according to some embodiments further includes a rotor 81 of the electric motor 8 and a stator 82 of the electric motor 8. The rotor 81 includes permanent magnets 83 and is mounted on the other side of the thrust plate portion 21 of the rotating shaft 2. The stator 82 includes a stationary coil portion 85 and is disposed opposite the rotor 81 on the outer periphery thereof, with a third gap S3 therebetween. A motor accommodation space 57A is formed within the bearing housing 51 to accommodate the rotor 81 and the stator 82 of the electric motor 8.

[0065] The rotor 81 further includes a permanent magnet support portion 84 that supports the permanent magnet 83. The permanent magnet support portion 84 is attached to the rotating shaft 2. The stator 82 further includes a stationary coil support portion 86 that supports the stationary coil portion 85. The stationary coil support portion 86 is supported by the bearing housing 51.

[0066] exist Figure 1 and Figure 2 In the illustrated embodiment, centrifugal compressor 1 is configured as an electric centrifugal compressor. Electric power is supplied from a power source (not shown) to electric motor 8, which drives and rotates rotary shaft 2. Some embodiments of the present invention are also applicable to centrifugal compressors 1 that do not include electric motor 8.

[0067] exist Figure 1 and Figure 2In the illustrated embodiment, cooling air inlet passage 69 includes annular second-side supply passages 693 and 694 extending in the circumferential direction, the motor accommodation space 57A, and a gap 104 formed between the one side journal bearing 101 and the rotating shaft 2. Gap 104 communicates with both the motor accommodation space 57A and the inner annular passage 68.

[0068] The other-side supply flow path 693 is formed on the other side of the motor accommodating space 57A in the bearing housing 51 and the gap 105 formed between the other-side journal bearing 102 and the rotating shaft 2. The other-side supply flow path 693 extends in the radial direction, has an inlet-side outer opening 691 formed at one end, and is connected to the gap 106 at the other end. The gap 106 is formed between the rotating shaft 2 and the bearing housing 51 on the other side of the gap 105 and on the side of the other-side impeller 32, and is connected to the adjacent gap 105 on the one side. The other-side supply flow path 694 extends in the axial direction, has one end connected to the other-side supply flow path 693, and the other end connected to the motor accommodating space 57A.

[0069] In some embodiments, as Figure 1 and Figure 2 As shown, the other-side cooling air introduction line 62 may be connected to a second air extraction line 112 for introducing the compressed air flowing through the relay line 11 into the introduction-side outer opening 691. One end of the second air extraction line 112 is connected to the relay line 11, and the other end is connected to the introduction-side outer opening 691. A portion of the compressed air flowing through the relay line 11 is extracted into the other-side cooling air introduction line 62 via the second air extraction line 112. In this embodiment, at least a portion of the cooling air flowing through the other-side cooling air introduction line 62 flows, for example, sequentially through the second air extraction line 112, the other-side supply flow paths 693 and 694, the motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. Furthermore, at least a portion of the cooling air flowing through the other-side cooling air introduction conduit 62 can sequentially flow through the second exhaust conduit 112, the other-side supply flow path 693, the gap 106, the gap 105, the motor accommodation space 57A, the gap 104, the inner annular flow path 68, and the second gap S2. In this embodiment, even if the blower 107 (described later) is not provided in the centrifugal compressor 1, cooling air can be supplied to the second gap S2 via the other-side cooling air introduction conduit 62, thereby preventing the centrifugal compressor 1 from increasing in size.

[0070] like Figure 1 and Figure 2As shown, in some embodiments, the other side cooling air introduction pipe 62 may also be connected to a blower 107 for pressurizing the cooling air introduced into the introduction side outer opening 691. In this embodiment, the cooling air is supplied to the other side cooling air introduction pipe 62 from the blower 107.

[0071] According to the above configuration, cooling air can be introduced from outside the bearing housing 51 (casing 5 ) into the inner annular flow path 68 through the cooling air introduction flow path 69 , and can also be introduced into the second gap S2 from the radially inner side.

[0072] (Cooling air exhaust line)

[0073] Figure 6 Schematic diagram of the cooling air exhaust pipe 7 in one embodiment of the present invention as viewed from one axial side. Figure 1 、 Figure 2 and Figure 6 As shown, the centrifugal compressor 1 according to some embodiments further includes a cooling air discharge line 7 for discharging cooling air from each of the first gap S1 and the second gap S2 to the outside of the bearing housing 51 (casing 5 ).

[0074] The cooling air discharge duct 7 includes a discharge-side annular flow path 71 and a cooling air discharge flow path 72 that are annular and extend in the circumferential direction. The discharge-side annular flow path 71 is formed inside the bearing housing 51 (housing 5) and is connected to the radially outer sides of the first gap S1 and the second gap S2. The cooling air discharge flow path 72 has a discharge-side outer opening 721 formed on the outer surface 56 of the bearing housing 51 (housing 5) and a discharge-side inner opening 722 formed in the discharge-side annular flow path 71. The cooling air flows from the first gap S1 and the second gap S2 through the discharge-side annular flow path 71 and the cooling air discharge flow path 72 in sequence, and is then discharged to the outside of the bearing housing 51. Figure 1 In the illustrated embodiment, the cooling air discharge flow path 72 extends in the aforementioned radial direction.

[0075] According to the above configuration, the cooling air that has flowed through the gaps S1 and S2 and cooled the thrust bearing 4 can be discharged to the outside of the casing 5 through the cooling air discharge duct 7. Furthermore, when the cooling air introduction duct 6 includes both the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, the cooling air is discharged to the outside of the casing 5 from the first gap S1 and the second gap S2 via the common cooling air discharge duct 7, thereby suppressing an increase in the size of the casing 5, and thus suppressing an increase in the size of the centrifugal compressor 1.

[0076] like Figure 2As shown, in some embodiments, the cooling air discharge flow path 72 is formed inside the bearing housing 51 (housing 5 ) and includes an internal space 57 having a larger volume than the discharge-side annular flow path 71 .

[0077] According to the above configuration, by providing the internal space 57 in the cooling air discharge flow path 72, which is larger than the volume of the discharge-side annular flow path 71, it is possible to suppress the formation of a circulating flow in the air bearing, i.e., the flow of cooling air from the radially outer side to the inner side within the thrust bearing 4, thereby promoting the flow of cooling air from the discharge-side annular flow path 71 into the internal space 57. Furthermore, by suppressing the formation of a circulating flow in the thrust bearing 4, it is possible to suppress the collision of the circulating flow with the cooling air supplied to the gaps S1 and S2, thereby promoting the supply of cooling air to the gaps S1 and S2.

[0078] like Figure 2 As shown, in some embodiments, the internal space 57 as a part of the cooling air exhaust flow path 72 is constituted by the motor accommodation space 57A. Figure 2 In the illustrated embodiment, the cooling air discharge flow path 72 includes a connecting flow path 72A having one end connected to the discharge-side annular flow path 71 and the other end connected to the motor accommodation space 57A at a radial position radially outward of the discharge-side annular flow path 71 and the stationary coil portion 85.

[0079] According to the above structure, by utilizing the motor accommodation space 57A as the internal space 57 provided in the cooling air exhaust flow path 72, there is no need to form an additional internal space 57 inside the casing 5, thereby suppressing the size of the casing 5 and further suppressing the size of the centrifugal compressor 1.

[0080] (Shielding part)

[0081] Figure 7 and Figure 8 Each of them is a schematic cross-sectional view of the impeller bearing 4 of the centrifugal compressor 1 according to one embodiment of the present invention. Figure 7 and Figure 8 As shown, in some embodiments, the one-side thrust bearing 41 has at least one (or multiple in the illustrated example) through-hole 43 extending radially therethrough. The centrifugal compressor 1 further includes a shielding portion 9 that covers the outer circumference (radially outer side) of the plurality of through-holes 43 and blocks the flow of gas into the plurality of through-holes 43.

[0082] like Figure 4 As shown, the through hole 43 can be formed between the top foil 412 and the elastic file 413, or between the elastic foil 413 and the support plate 414. In the shielding part 9, the gap between the shielding part 9 and the thrust bearing 41 on one side is preferably small. Figure 7As shown, the shielding portion 9 can be installed on one side of the thrust bearing support portion 54, or can be formed as one piece with the thrust bearing support portion 54. In addition, the shielding portion 9 can also be formed as one piece with the thrust bearing 41 on one side. It can also be installed on the other side of the thrust bearing 41. Figure 8 In the illustrated embodiment, the shielding portion 9 is formed by bending the outer peripheral end portion of the support plate 414 .

[0083] In some embodiments, as Figure 7 and Figure 8 As shown, the other-side thrust bearing 42 has at least one (or multiple in the illustrated example) through-hole 43A extending radially therethrough. The centrifugal compressor 1 further includes a shielding portion 9A that covers the outer circumference (radially outer side) of the plurality of through-holes 43A and blocks the flow of gas into the plurality of through-holes 43A.

[0084] like Figure 4 As shown, the through hole 43A can be formed between the top foil 422 and the elastic foil 423, or between the elastic foil 423 and the support plate 424. In the shielding portion 9A, the gap between the shielding portion 9A and the other side thrust bearing 42 is preferably small. Figure 7 As shown, the shielding portion 9A can be mounted on the other side thrust bearing support portion 55, or can be formed as one piece with the other side thrust bearing support portion 55. Furthermore, the shielding portion 9A can also be formed as one piece with the other side thrust bearing 42. It can also be mounted on the other side thrust bearing 42. Figure 8 In the illustrated embodiment, the shielding portion 9A is formed by bending the outer peripheral end portion of the support plate 424 .

[0085] According to the above configuration, the shielding portions 9 and 9A are provided to prevent cooling air from flowing into the through-holes 43 and 43A of the thrust bearing 4. This prevents the formation of a circulating flow within the thrust bearing 4, i.e., cooling air flowing from the radially outer side to the inner side of the through-holes 43 and 43A of the thrust bearing 4. This facilitates the discharge of cooling air from the discharge-side annular flow path 71. Furthermore, by preventing the formation of a circulating flow within the thrust bearing 4, this circulating flow is prevented from colliding with the cooling air supplied to the gaps S1 and S2, thereby facilitating the supply of cooling air to the gaps S1 and S2.

[0086] In this specification, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" that indicate relative or absolute configurations not only indicate such configurations in a strict sense, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree that the same function can be achieved.

[0087] For example, expressions such as “same,” “equal,” and “homogeneous” that indicate that things are in the same state not only refer to the same state in a strict sense but also refer to a state with a tolerance or a difference to the extent that the same function can be achieved.

[0088] Furthermore, in this specification, expressions indicating shapes such as quadrilaterals or cylinders not only indicate shapes such as quadrilaterals or cylinders in a strict geometric sense, but also indicate shapes including concave and convex portions or chamfered portions within a range that can achieve the same effect.

[0089] Furthermore, in this specification, expressions such as “including,” “comprising,” or “having” with respect to one constituent element are not exclusive expressions that exclude the presence of other constituent elements.

[0090] The present invention is not limited to the above-described embodiment, and includes additional modifications to the above-described embodiment and appropriate combinations of these embodiments.

[0091] The contents described in some of the above embodiments can be understood, for example, as follows.

[0092] 1) A centrifugal compressor 1 according to at least one embodiment of the present invention includes:

[0093] Rotation axis 2;

[0094] at least one compressor impeller 3 mounted on at least one of one side or the other side of the rotating shaft 2;

[0095] The thrust disc portion 21 is provided on the rotating shaft 2 and extends along the radial direction of the rotating shaft 2;

[0096] at least one thrust bearing 4, which is an air bearing, is disposed on the one side or the other side of the rotating shaft 2 relative to the thrust plate portion 21 and faces the thrust plate portion 21 with gaps S1 and S2 therebetween;

[0097] a housing 5 rotatably accommodating the rotating shaft 2 and the thrust disc portion 21 and supporting the at least one thrust bearing 4; and

[0098] At least one cooling air introduction duct 6 is configured to introduce cooling air from the outside of the housing 5 into the gaps S1 and S2 from the inside in the radial direction.

[0099] According to the configuration 1) above, the cooling air in the gaps S1 and S2 is pushed (sucked) radially outward as the rotating shaft 2 rotates. This suction facilitates the supply of cooling air from the cooling air inlet pipe 6 to the gaps S1 and S2 and the radial outward movement of the cooling air in the gaps S1 and S2, thus facilitating the supply of the required amount of cooling air to the gaps S1 and S2. This centrifugal compressor 1 can effectively cool the thrust bearing 4, which serves as an air bearing.

[0100] 2) In some embodiments, according to the centrifugal compressor 1 described in 1) above,

[0101] The at least one compressor impeller 3 includes a side impeller 31 mounted on the one side of the rotating shaft 2.

[0102] The at least one thrust bearing 4 includes a side thrust bearing 41 disposed on the side closer to the rotating shaft 2 than the thrust plate portion 21 and facing the thrust plate portion 21 with a first gap S1.

[0103] The at least one cooling air introduction duct 6 includes a side cooling air introduction duct 61 configured to introduce the cooling air from the outside of the housing 5 into the first gap S1 from the inside in the radial direction.

[0104] According to the configuration 2) above, the supply of cooling air from the cooling air introduction duct 61 to the first gap S1 and the radially outward movement of the cooling air in the first gap S1 are promoted by suction, thereby facilitating the supply of a required amount of cooling air to the first gap S1.

[0105] 3) In some embodiments, the centrifugal compressor 1 described in 1) or 2) above, wherein:

[0106] The at least one compressor impeller 3 includes the other impeller 32 mounted on the other side of the rotating shaft 2.

[0107] The at least one thrust bearing 4 includes a second thrust bearing 42 disposed on the side closer to the rotating shaft 2 than the thrust plate portion 21 and facing the thrust plate portion 21 with a second gap S2.

[0108] The at least one cooling air introduction duct 6 includes a second cooling air introduction duct 62 configured to introduce the cooling air from the outside of the housing 5 into the second gap S2 from the inside in the radial direction.

[0109] According to the configuration in 3) above, suction facilitates the supply of cooling air from the other-side cooling air introduction duct 62 to the second gap S2 and the radially outward movement of cooling air present in the second gap S2, thereby facilitating the supply of the required amount of cooling air to the second gap S2. Furthermore, when the cooling air introduction duct 6 includes both the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, by configuring the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62 as separate ducts, it is easier to ensure the amount of cooling air delivered to the first gap S1 and the second gap S2. Furthermore, by supplying cooling air to both the first gap S1 and the second gap S2 via the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, the thrust bearing 4 can be cooled more effectively.

[0110] 4) In some embodiments, according to the centrifugal compressor 1 described in 2) above,

[0111] The cooling air inlet pipe 61 on one side includes:

[0112] an annular inner annular flow path 63 formed inside the housing 5 and connected to the radially inner side of the first gap S1; and

[0113] The cooling air introduction flow path 64 includes an introduction-side outer opening 641 formed on the outer surface 56 of the housing 5 and an introduction-side inner opening 642 formed on the side closer to the connection portion of the inner annular flow path 63 with the first gap S1 .

[0114] According to the configuration of 4), cooling air can be introduced from outside the housing 5 into the inner annular flow path 63 through the cooling air introduction flow path 64 and introduced into the first gap S1 from the radially inner side.

[0115] 5) In some embodiments, according to the centrifugal compressor 1 described in 4) above,

[0116] The cooling air inlet flow path 64 includes:

[0117] The outer annular flow path 65 is formed on the outer side of the inner annular flow path 63 in the radial direction;

[0118] a plurality of inner supply flow paths 66 , one end of which is connected to the inner annular flow path 63 and the other end of which is connected to the outer annular flow path 65 , and which are arranged at intervals in the circumferential direction of the rotating shaft 2 ; and

[0119] The outer supply flow path 67 is connected to the outer annular flow path 65 at one end, and has the introduction-side outer opening 641 formed at the other end.

[0120] According to the configuration of 5), cooling air can be introduced from the plurality of inner supply channels 66 to the plurality of locations in the circumferential direction of the inner annular channel 63 , thereby enabling cooling by cooling air over a relatively wide range in the circumferential direction of the first gap S1 .

[0121] 6) In some embodiments, the centrifugal compressor 1 according to any one of 1) to 5) above further comprises:

[0122] The cooling air exhaust pipe 7 is used to exhaust the cooling air from the gaps S1 and S2 to the outside of the housing 5.

[0123] The cooling air exhaust pipeline 7 includes:

[0124] An annular discharge-side annular flow path 71 is formed inside the housing 5 and connected to the radially outer sides of the gaps S1 and S2; and

[0125] The cooling air discharge flow path 72 includes a discharge-side outer opening 721 formed in the outer surface 56 of the housing 5 and a discharge-side inner opening 722 formed in the discharge-side annular flow path 71 .

[0126] According to the configuration of 6) above, the cooling air that has flowed through the gaps S1 and S2 and cooled the thrust bearing 4 can be discharged to the outside of the casing 5 through the cooling air discharge duct 7. Furthermore, when the cooling air introduction duct 6 includes both the one-side cooling air introduction duct 61 and the other-side cooling air introduction duct 62, the cooling air is discharged to the outside of the casing 5 from the first gap S1 and the second gap S2 through the common cooling air discharge duct 7. This can suppress an increase in the size of the casing 5, and thus, suppress an increase in the size of the centrifugal compressor 1.

[0127] 7) In some embodiments, according to the centrifugal compressor 1 described in 6) above,

[0128] The cooling air exhaust flow path 72 includes:

[0129] The internal space 57 is formed inside the housing 5 and has a volume larger than that of the discharge-side annular flow path 71 .

[0130] According to the configuration of 7) above, by providing the internal space 57 in the cooling air discharge flow path 72, which has a larger volume than that of the discharge-side annular flow path 71, it is possible to suppress the formation of a circulating flow in the thrust bearing 4, which serves as an air bearing, thereby promoting the flow of cooling air from the discharge-side annular flow path 71 into the internal space 57. Furthermore, by suppressing the formation of a circulating flow in the thrust bearing 4, it is possible to suppress the collision of the circulating flow with the cooling air supplied to the gaps S1 and S2, thereby promoting the supply of cooling air to the gaps S1 and S2.

[0131] 8) In some embodiments, the centrifugal compressor 1 according to 7) above further comprises:

[0132] The rotor 81 of the motor 8 includes a permanent magnet 83 and is mounted on the other side of the thrust plate portion 21 of the rotating shaft 2; and

[0133] The stator 82 of the motor 8 includes a stationary coil portion 85 and is disposed on the outer circumference of the rotor 81 to face the rotor 81 with a third gap S3 therebetween.

[0134] The internal space 57 is formed of a motor accommodation space 57A that accommodates the rotor 81 and the stator 82 of the motor 8 .

[0135] According to the structure of 8) above, by utilizing the motor accommodation space 57A as the internal space 57 provided in the cooling air exhaust flow path 72, there is no need to form an additional internal space 57 inside the casing 5, thereby suppressing the enlargement of the casing 5 and further suppressing the enlargement of the centrifugal compressor 1.

[0136] 9) In some embodiments, according to the centrifugal compressor 1 described in any one of 1) to 8),

[0137] The at least one thrust bearing 4 has at least one through hole 43, 43A penetrating in the radial direction.

[0138] The centrifugal compressor 1 further includes a shielding portion 9 that covers the outer peripheral side of the at least one through-hole 43 , 43A and blocks the flow of gas into the at least one through-hole 43 , 43A.

[0139] According to the configuration of item 9), the shielding portion 9 prevents the flow of cooling air into the through-holes 43 and 43A of the thrust bearing 4, thereby suppressing the formation of a circulating flow in the thrust bearing 4. This promotes the discharge of cooling air from the discharge-side annular flow path 71. Furthermore, by suppressing the formation of a circulating flow in the thrust bearing 4, the circulating flow is prevented from colliding with the cooling air supplied to the gaps S1 and S2, thereby promoting the supply of cooling air to the gaps S1 and S2.

[0140] Explanation of symbols

[0141] 1-Centrifugal compressor, 2-Rotating shaft, 3-Compressor impeller, 4-Thrust bearing, 5-Casing, 6-Cooling air inlet pipe, 7-Cooling air exhaust pipe, 8-Motor, 9, 9A-Shielding part, 11-Relay pipe, 12-Fuel cell, 13-Compressed air inlet pipe, 21-Thrust plate part, 31-One side impeller, 32-Other side impeller, 41-One side thrust bearing, 42-Other side thrust bearing, 43, 43A-Through hole, 51-Bearing housing, 52-One side housing, 53-Other side housing, 54-One side thrust bearing support part, 55-Other side thrust bearing support part, 56-Outer surface, 57-Inner space, 57A-Motor accommodating space, 61-One side cooling air inlet pipe, 62-Other side cooling air inlet pipe, 63, 68-Inner annular flow path, 64, 69-Cooling air inlet flow path, 65-Outer Annular flow path, 66 - inner supply flow path, 67 - outer supply flow path, 71 - discharge side annular flow path, 72 - cooling air discharge flow path, 81 - rotor, 82 - stator, 83 - permanent magnet, 84 - permanent magnet support, 85 - stationary coil, 86 - stationary coil support, 101, 102 - journal bearings, 103, 107 - blowers, 104, 105, 106 - gaps, 111 - first exhaust pipe Road, 112-the second exhaust pipe, 412, 422-top foil, 413, 423-elastic foil, 414, 424-support plate, 641, 691-outer opening of the inlet side, 642, 692-inner opening of the inlet side, 721-outer opening of the discharge side, 722-inner opening of the discharge side, CA-center axis, P1, P2-connecting part, S1-the first gap, S2-the second gap, S3-the third gap.

Claims

1. A centrifugal compressor comprising: Rotation axis; at least one compressor impeller mounted on at least one of one side or the other side of the rotating shaft; a thrust disc portion, disposed on the rotating shaft and extending along the radial direction of the rotating shaft; at least one thrust bearing, which is an air bearing, is disposed on the one side or the other side of the rotation axis relative to the thrust plate portion and faces the thrust plate portion with a gap therebetween; a housing rotatably accommodating the rotating shaft and the thrust disc portion and supporting the at least one thrust bearing; and At least one cooling air introduction duct is configured to introduce cooling air from the outside of the housing into the gap from the inside in the radial direction.

2. The centrifugal compressor according to claim 1, wherein: The at least one compressor impeller includes a side impeller mounted on the one side of the rotating shaft, The at least one thrust bearing includes a side thrust bearing that is arranged on the side closer to the rotating shaft than the thrust plate portion and faces the thrust plate portion with a first gap therebetween. The at least one cooling air introduction duct includes a side cooling air introduction duct configured to introduce the cooling air from the outside of the housing into the first gap from the inside in the radial direction.

3. The centrifugal compressor according to claim 1 or 2, wherein: The at least one compressor impeller includes another impeller mounted on the other side of the rotating shaft. The at least one thrust bearing includes a second thrust bearing that is arranged on the side closer to the rotating shaft than the thrust plate portion and faces the thrust plate portion with a second gap therebetween. The at least one cooling air introduction duct includes another cooling air introduction duct configured to introduce the cooling air from the outside of the housing into the second gap from the inside in the radial direction.

4. The centrifugal compressor according to claim 2, wherein: The cooling air inlet pipeline on one side includes: an annular inner annular flow path formed inside the housing and connected to the radial inner side of the first gap; and The cooling air introduction flow path includes an introduction-side outer opening formed on the outer surface of the housing and an introduction-side inner opening formed on the side of the inner annular flow path closer to the first gap connection portion.

5. The centrifugal compressor according to claim 4, wherein: The cooling air inlet flow path includes: an outer annular flow path formed further outward in the radial direction than the inner annular flow path; a plurality of inner supply flow paths, one end of which is connected to the inner annular flow path and the other end of which is connected to the outer annular flow path, and which are arranged at intervals in the circumferential direction of the rotating shaft; and The outer supply flow path has one end connected to the outer annular flow path and the other end thereof is formed with the introduction-side outer opening.

6. The centrifugal compressor according to any one of claims 1, 2, 4, and 5, further comprising: a cooling air exhaust pipe, used for exhausting the cooling air from the gap to the outside of the housing, The cooling air exhaust pipeline includes: an annular discharge-side annular flow path formed inside the housing and connected to the radially outer side of the gap; and The cooling air discharge flow path includes a discharge-side outer opening formed on the outer surface of the housing and a discharge-side inner opening formed in the discharge-side annular flow path.

7. The centrifugal compressor according to claim 6, wherein: The cooling air exhaust flow path includes: The internal space is formed inside the housing and has a volume larger than that of the discharge-side annular flow path.

8. The centrifugal compressor according to claim 7, further comprising: a rotor of the electric motor, including a permanent magnet and mounted on the other side of the thrust plate portion of the rotating shaft; and The stator of the motor includes a stationary coil portion and is disposed on the outer circumference of the rotor to face the rotor with a third gap therebetween. The internal space is formed of a motor accommodation space that accommodates the rotor and the stator of the motor.

9. The centrifugal compressor according to any one of claims 1, 2, 4 and 5, wherein: The at least one thrust bearing has at least one through hole penetrating along the radial direction. The centrifugal compressor further includes a shielding portion that covers an outer peripheral side of the at least one through-hole and blocks the flow of gas into the at least one through-hole.

Images