Turbofluidic machine with cooling for a film storage

Abstract

A turbofluid machine (10) has: a partition (16) separating the interior of a housing (11) into a compression chamber (13b) and a bearing chamber (S2); and a foil bearing (30). The partition (16) has a bearing part (60) having an end surface (60a) that rises axially towards a pressure ring (24d). The bearing part (60) has a groove (61) extending in the end surface (60a) and radially to an outer edge surface (60b) of the bearing part (60). The uppermost foils (33) of the foil bearing (30) each have one surface (33c) facing the pressure ring (24d) and the other surface elastically supported by a corresponding corrugated foil (32) of the foil bearing (30).The foil bearing (30) is mounted on the end surface (60a) such that a position of the groove (61) corresponds to a position of a gap between the corrugated foils (32) and the position of a gap between the uppermost corrugated foils (32), and such that the groove (61) is directed in the axial direction to the pressure ring (24d).

Description

[0001] The present invention relates to a turbofluid machine.

[0002] The domestic republishing of the international publication of PCT patent application no. WO 2020 / 130124A1 discloses a known turbofluid machine. This turbofluid machine has a rotary shaft configured to rotate the axis of the rotary shaft, a pressure ring having a disc-like shape, an actuating element, and a housing for receiving the rotary shaft, pressure ring, and actuating element. The pressure ring extends from an edge surface of the rotary shaft in the radial direction of the rotary shaft and is rotatable with the rotary shaft. The actuating element is configured to rotate with the rotary shaft to compress and discharge a fluid.

[0003] This turbofluid machine also has a shaft bearing element with a disc-like shape and a foil bearing. The shaft bearing element has an insertion bore formed through it, through which the rotating shaft is inserted. The foil bearing supports the pressure ring in the axial direction of the rotating shaft such that the pressure ring is rotatable relative to the shaft bearing element.

[0004] The foil bearing comprises multiple corrugated foils, each formed from a thin, elastic disc with a wave-like shape, and multiple top foils, each formed from a thin, elastic disc. The corrugated foils are mounted on one end face of the shaft bearing element adjacent to the pressure ring and spaced apart from each other around the insertion bore. Each top foil has one surface facing the pressure ring, and the other surface is elastically supported by the corrugated foils. The surface of the top foil adjacent to the pressure ring serves as a bearing surface, and the surface of the pressure ring adjacent to the top foil serves as a bearing contact surface, oriented in the axial direction of the rotating shaft toward the bearing surface.

[0005] In the foil bearing, the rotating pressure ring is supported by the top foil at low rotational speeds of the rotating shaft, with the top foil in contact with the pressure ring. At high rotational speeds of the rotating shaft, the pressure ring is supported by a fluid film generated in a gap between the bearing contact surface and the bearing surface, without the top foil touching the pressure ring.

[0006] It is likely that this type of foil bearing will experience high temperatures, since the top foil is formed from an elastic thin disc which has a low heat capacity, so the foil bearing may have a problem of thermal resistance of the top foil.

[0007] This known turbofluid machine has a cooling passage in the housing designed to cool the foil bearing (see WO 2020 / 130 124 A1, third embodiment, Fig. 7 and Fig. 8) The cooling fluid in the cooling passage is introduced into a chamber (i.e., an opposite chamber) located on the opposite side of the pressure ring with respect to the shaft bearing element. The fluid introduced into the opposite chamber then flows through a gap between the insertion bore of the shaft bearing element and the rotating shaft into a chamber (i.e., bearing chamber) between the shaft bearing element and the pressure ring, and through a through-bore formed by the shaft bearing element in the axial direction. The cooling fluid introduced into the bearing chamber flows radially outward through a circumferential gap extending between the circumferentially adjacent corrugated sheets to cool the uppermost sheets and the corrugated sheets.

[0008] However, if such a turbofluid machine has a compression chamber in the opposite space for accommodating the actuating element, a partition wall must be formed in the opposite space, separate from the shaft bearing element, to define the compression chamber. This is necessary to avoid reducing the efficiency of the fluid compression by the actuating element when the cooling fluid for cooling the foil bearing is introduced into the opposite space relative to the shaft bearing element. Providing the partition wall necessitates an increase in the size of the turbofluid machine in the axial direction.

[0009] Publication US 2011 / 0243762A1 is considered the closest prior art. It discloses the features in the preamble of claim 1.

[0010] Document CN 1 12 855 749 A discloses a bearing component having a groove and a foil bearing with a plurality of corrugated foils and a plurality of top foils. The corrugated foils are arranged around an insertion hole with a gap between the adjacent corrugated foils. The top foils are arranged analogously with a gap between the adjacent top foils. The position of the gap between the corrugated foils and the top foils in the assembled state coincides with the position of the groove of the bearing component.

[0011] Considering the problem mentioned above, the object of the invention is to provide a turbofluid machine capable of effectively cooling a foil bearing without increasing the size of the turbofluid machine in the axial direction.

[0012] The object of the invention is achieved by a foil bearing according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0013] According to one aspect of the present invention, a turbofluid machine is provided, comprising: a rotary shaft, a pressure ring, an actuating element, a housing, a partition, and a foil bearing. The rotary shaft is configured to rotate an axis of the rotary shaft. The pressure ring has a disk-like shape and extends from an edge surface of the rotary shaft in a radial direction along the rotary shaft. The pressure ring is rotatable with the rotary shaft. The actuating element is configured to rotate with the rotary shaft to compress and discharge a fluid. The housing accommodates the rotary shaft, the pressure ring, and the actuating element. The partition has an insertion bore formed through the partition, through which the rotary shaft is inserted. The partition divides the interior of the housing into a compression chamber, in which the actuating element is accommodated, and a bearing chamber, in which the pressure ring is accommodated.The foil bearing supports the pressure ring in an axial direction of the rotating shaft such that the pressure ring is rotatable relative to the partition. The partition has a bearing section with an end face that is raised axially towards the pressure ring. The bearing section has a groove formed in the interface and extending radially towards an outer edge surface of the bearing section. The foil bearing comprises: a plurality of corrugated foils, each formed from an elastic thin disk having a corrugated shape and mounted on the end face; and a plurality of top foils, each formed from an elastic thin disk. The corrugated foils are arranged around the insertion bore with a gap between the adjacent corrugated foils.The top sheets are arranged around the insertion bore with a gap between the adjacent top sheets, and each sheet has one surface facing the pressure ring and the other surface elastically supported by the corresponding corrugated sheet. The sheet bearing is mounted on the bearing part such that one position of the groove corresponds to a position of the gap between the corrugated sheets and a position of the gap between the top sheets, and such that the groove is oriented axially towards the pressure ring.

[0014] Other aspects and advantages of the invention will become clear from the following description, which should be considered in conjunction with the attached drawings, which illustrate the basis of the invention by way of example.

[0015] The present invention, together with its tasks and advantages, will best be understood by reference to the following description of the embodiments together with the attached drawings, in which: Fig. 1 is a sectional view of a turbo compressor according to a first embodiment; Fig. 2 is an enlarged partial sectional view of the turbo compressor according to the first embodiment; Fig. 3 is another enlarged partial sectional view of the turbo compressor according to the first embodiment. Fig. 4 a perspective view of a fourth disk of the turbo compressor according to the first embodiment is Fig. 5 a perspective view of the turbo compressor according to the first embodiment, which shows a second disk serving as a partition; Fig. 6 is a top view of the turbo compressor according to the first embodiment, which represents a bearing part of the partition wall in which a corrugated film is arranged; Fig. 7 is a top view of the turbo compressor according to the first embodiment, which shows the bearing part of the partition in which a top foil is arranged; Fig. 8 is a sectional view of the turbo compressor according to the first embodiment, illustrating the actuation of an axial foil bearing; Fig. 9 is a sectional view of the turbo compressor according to the first embodiment, which illustrates the actuation of the axial foil bearing; Fig. 10 a perspective view of a turbo compressor according to a second embodiment, which represents a second disk serving as a partition; Fig. 11 a sectional view of the turbo compressor according to the second embodiment along a line XI-XI of the Fig. 10 is; and Fig. 12 is a top view of a turbo compressor according to a third embodiment, which represents a bearing part of a partition wall in which a top foil is arranged.

[0016] The first to third embodiments of the present invention are described in detail below with reference to the attached drawings.

[0017] According to this embodiment, a turbo compressor 10 serves as the turbofluid machine of the present invention. The turbo compressor 10 is mounted on a fuel cell vehicle that has a fuel cell system 1. The fuel cell system 1 supplies oxygen and hydrogen to a fuel cell mounted on the vehicle for the generation of electricity. The turbo compressor 10 compresses oxygen-containing air that is supplied to the fuel cell.

[0018] As in the Fig. As shown in Figure 1, the turbo compressor 10, which serves as the turbofluid machine of the present invention, has a housing 11. The housing 11 is made of a metal such as an aluminum alloy. The housing 11 has a motor housing 12, a compressor housing 13, a turbine housing 14, a first disk 15, a second disk 16, a third disk 17, and a fourth disk 29. The second disk 16 serves as the partition of the present invention.

[0019] The motor housing 12 has a disc-shaped end wall 12a and a side wall 12b. The side wall 12b has a cylindrical shape and projects from an outer edge section of the end wall 12a. The first disk 15 is connected to an open end of the side wall 12b of the motor housing 12 to close an opening in the side wall 12b.

[0020] In the motor housing 12, an inner surface 121a of the end wall 12a, an inner edge surface 121b of the edge wall 12b, and an end surface 15a of the first disk 15 adjacent to the motor housing 12 interact to define a motor chamber S1. The motor chamber S1 accommodates an electric motor 18.

[0021] The first disk 15 has a first bearing retaining section 20. The first bearing retaining section 20 projects from the central section of the end surface 15a of the first disk 15 towards the electric motor 18. The first bearing retaining section 20 has a cylindrical shape.

[0022] The other end face 15b of the first disk 15 is located away from the motor housing 12 and has a recess 15c with a bottom surface 15d. The recess 15c is in the form of a circular hole. The cylindrical first bearing retaining section 20 is open through the first disk 15 towards the bottom surface 15d of the recess 15c. The recess 15c is coaxial with the first bearing retaining section 20. The recess 15c has an inner edge surface 15e through which the end face 15b is connected to the bottom surface 15d.

[0023] The motor housing 12 has a second bearing retaining section 22. The second bearing retaining section 22 projects from the central section of the inner surface 121a of the end wall 12a of the motor housing 12 towards the electric motor 18. The second bearing retaining section 22 has a cylindrical shape. The cylindrical second bearing retaining section 22 is open through the end wall 12a of the motor housing 12 at an outer surface 122a of the end wall 12a. The first bearing retaining section 20 is coaxial with the second bearing retaining section 22.

[0024] As from the Fig. As can be seen in Figure 2, the fourth disk 29 is connected to the end face 15b of the first disk 15. As can be seen from the Fig. As can be seen in Figure 4, the fourth disk 29 has an annular shape and a central bore 29a. The central bore 29a is connected to the recess 15c. The fourth disk 29 has a connecting groove 29c formed in an end surface 29b of the fourth disk 29 that is located away from the first disk 15. The connecting groove 29c extends radially along the fourth disk 29, and the opposite ends of the connecting groove 29c are open at the outer and inner edge surfaces of the fourth disk 29, respectively. The connecting groove 29c extends radially from the outer edge surface of the fourth disk 29 to the axis of the rotating shaft 24a.

[0025] The second disk 16 is connected to the end surface 29b of the fourth disk 29. The second disk 16 has a shaft insertion bore 16a, which serves as the insertion bore of the present invention, formed through the central section of the second disk 16 and through which the rotating shaft 24a is inserted. The shaft insertion bore 16a is connected to recess 15c through the central bore 29a. The shaft insertion bore 16a is coaxial with the central bore 29a, the recess 15c, and the first bearing retaining section 20. The second disk 16 has an end surface 16b that is adjacent to the fourth disk 29, and the end surface 16b interacts with the central bore 29a of the fourth disk 29 and recess 15c of the first disk 16 to form a thrust bearing receiving chamber S2. The thrust bearing receiving chamber S2 serves as a storage space for the present invention.

[0026] The compressor housing 13 has a cylindrical shape and a circular, perforated inlet 13a through which air is drawn into the compressor housing 13. The compressor housing 13 is connected to an end face 16c of the second disk 16, which is spaced apart from the first disk 15. The inlet 13a of the compressor housing 13 is coaxial with the shaft insertion bore 16a of the second disk 16 and the first bearing retaining section 20. The inlet 13a is open on an end face of the compressor housing 13 that is spaced apart from the second disk 16.

[0027] A first impeller chamber 13b, a discharge chamber 13c, and a first diffuser passage 13d are formed between the compressor housing 13 and the end face 16c of the second disk 16. The first impeller chamber 13b is connected to the inlet 13a. The discharge chamber 13c extends around the axis of the inlet 13a surrounding the first impeller chamber 13b. The first impeller chamber 13b is connected to the discharge chamber 13c through the first diffuser passage 13d. The first impeller chamber 13b is connected to the shaft insertion bore 16a of the second disk. The first impeller chamber 13b serves as the compression chamber of the present invention.

[0028] As from the Fig. As can be seen in Figure 3, the third disk 17 is connected to the outer surface 122a of the end wall 12a of the motor housing 12. The third disk 17 has a shaft insertion bore 17a on its central section. The shaft insertion bore 17a is connected to the cylindrical second bearing retaining section 22. The shaft insertion bore 17a is coaxial with the second bearing retaining section 22.

[0029] The turbine housing 14 has a cylindrical shape and features a circular outlet 14a through which air is discharged. The turbine housing 14 is connected to an end face 17b of the third disk 17, which is spaced apart from the motor housing 12. The outlet 14a of the turbine housing 14 is coaxial with the shaft insertion bore 17a of the third disk 17 and the second bearing retaining section 22. The outlet 14a opens at an end face of the turbine housing 14 that is located away from the third disk 17.

[0030] A second impeller chamber 14b, an intake chamber 14c, and a second diffuser passage 14d are formed between the turbine housing 14 and the end face 17b of the third disk 17. The second impeller chamber 14b is connected to the outlet 14a. The intake chamber 14c extends around the axis of the outlet 14a surrounding the second impeller chamber 14b. The second impeller chamber 14b is connected to the intake chamber 14c via the second diffuser passage 14d. The second impeller chamber 14b is connected to the shaft insertion bore 17a of the third disk 17.

[0031] As from the Fig. As can be seen in Figure 1, a rotating element 24 is received in the housing 11. The rotating element 24 has a rotating shaft 24a as a shaft section, a first supported section 24b, a second supported section 24c, and a third supported section 24d. The rotating shaft 24a has a first end section 24e as one end adjacent to the compressor housing 13 and a second end section 24f as one end adjacent to the turbine housing 14. The first supported section 24b is formed in part of an outer edge surface 240a of the rotating shaft 24a adjacent to the first end section 24e and is provided in the cylindrical first bearing retaining section 20. The first supported section 24b is formed integrally with the rotating shaft 24a and projects from the outer edge surface 240a of the rotating shaft 24a in such a way that it has an annular shape.

[0032] The second supported section 24c is formed in a portion of the outer edge surface 240a of the rotating shaft 24a adjacent to the second end section 24f and is provided in the cylindrical second bearing retaining section 22. The second supported section 24c has a cylindrical shape such that it projects from the outer edge surface 240a of the rotating shaft 24a in an annular shape and is attached to the outer edge surface 240a of the rotating shaft 24a. The second supported section 24c is rotatable together with the rotating shaft 24a.

[0033] The third supported section 24d is provided in the axial bearing receiving chamber S2. The third supported section 24d has a disk shape (e.g., disc-like shape) such that it extends from the outer edge surface 240a of the rotating shaft 24a in the radial direction of the rotating shaft 24a, forming a ring shape, and it is attached to the outer edge surface 240a of the rotating shaft 24a. The third supported section 24d is rotatable together with the rotating shaft 24a. The third supported section 24d is spaced axially from the electric motor 18. The third supported section 24d serves as the pressure ring of the present invention.

[0034] In the following description, directions such as the axial direction, the circumferential direction, and the radial direction are designations for the directions of the rotating shaft 24a. One side and the other side in the axial direction accordingly mean one side on which the first end section 24e of the rotating shaft 24a is located, and one side on which the second end section 24f of the rotating shaft 24a is located.

[0035] The first end section 24e of the rotating shaft 24a is connected to a first impeller 25, which serves as the actuating element of the present invention. The first impeller 25 is located closer to the first end section 24e than to the third supported section 24d of the rotating shaft 24a. The first impeller 25 is housed in the first impeller chamber 13b. The second end section 24f of the rotating shaft 24a is connected to a second impeller 26. The second impeller 26 is located closer to the second end section 24f than to the second supported section 24c of the rotating shaft 24a. The second impeller 26 is housed in the second impeller chamber 14b. The first impeller 25, the second impeller 26, and the rotating element 24 are housed in the casing 11.

[0036] A first sealing element 27 is provided between the shaft insertion bore 16a of the second disk 16 and the rotating shaft 24a. The first sealing element 27 seals a gap between the shaft insertion bore 16a and the rotating shaft 24a to prevent air from escaping from the first impeller chamber 13b to the motor chamber S1. A second sealing element 28 is provided between the shaft insertion bore 17a of the third disk 17 and the rotating element 24. The second sealing element 28 seals a gap between the shaft insertion bore 17a and the rotating shaft 24a to prevent air from escaping from the second impeller chamber 14b to the motor chamber S1. The first sealing element 27 and the second sealing element 28 are, for example, each a sealing ring. The first sealing element 27 serves as the sealing element of the present invention.

[0037] The second disk 16 has the first sealing element 27 in the shaft insertion bore 16a to seal the gap between the shaft insertion bore 16a and the rotating shaft 24a in such a way that the interior of the housing 11 is separated into the first impeller chamber 13b and the axial bearing receiving chamber S2.

[0038] The electric motor 18 has a cylindrical rotor 31 and a cylindrical stator 35. The rotor 31 is attached to the rotating shaft 24a. The stator 35 is mounted in the housing 11. The rotor 31 is arranged radially inside the stator 35 and rotates together with the rotating element 24. The rotor 31 has a cylindrical rotor core 31a, which is attached to the rotating shaft 24a, and a plurality of permanent magnets (not shown) provided in the rotor core 31a. The stator 35 surrounds the rotor 31. The stator 35 has a stator core 35a and a coil 34. The stator core 35a has a cylindrical shape and is attached to the inner edge surface 121b of the circumferential wall 12b of the motor housing 12. The coil 34 is wound around the stator core 35a. The coil 34 receives a current from a battery (not shown), so that the rotor 31 is rotated together with the rotating element 24.

[0039] Fuel cell system 1 comprises a fuel cell stack 100 as a vehicle-mounted fuel cell, a turbo compressor 10, a supply port L1, a discharge port L2, and a branch port L3. The fuel cell stack 100 contains multiple fuel cells. The fuel cell stack 100 is connected to the discharge chamber 13c via the supply port L1. The fuel cell stack 100 is also connected to the intake chamber 14c via the discharge port L2. The branch port L3, which includes an intercooler 110, branches off from the supply port L1. The intercooler 110 cools the air flowing through the branch port L3.

[0040] When the rotating element 24 rotates together with the rotor 31, the first impeller 25 and the second impeller 26 rotate along with the rotating element 24. This rotation compresses air drawn in through the inlet 13a by the first impeller 25 in the first impeller chamber 13b, and discharges it from the discharge chamber 13c through the first diffuser passage 13d. The air discharged from the discharge chamber 13c is fed to the fuel cell stack 100 through the supply passage L1. The air supplied to the fuel cell stack 100 is used by the fuel cell stack 100 to generate electricity, and the used air is then discharged as exhaust gas from the fuel cell stack 100 to the discharge passage L2. The exhaust gas from the fuel cell stack 100 is drawn through the discharge passage L2 into the intake chamber 14c.The exhaust gas drawn into the intake chamber 14c is then discharged to the second impeller chamber 14b through the second diffuser passage 14d. The exhaust gas discharged into the second impeller chamber 14b rotates the second impeller 26. The rotating element 24 is driven to rotate the electric motor 18, and also by the rotation of the second impeller 26 by the exhaust gas from the fuel cell stack 100. The first impeller 25, which serves as the actuating element of the present invention, is rotated together with the rotating element 24 to compress and discharge the air, which serves as the fluid of the present invention. The exhaust gas discharged into the second impeller chamber 14b is released to the outside through the outlet 14a.

[0041] In the following description, the rotating element 24 is rotated together with the rotor 31 in a direction of rotation R. In this embodiment, the direction of rotation of the rotating shaft 24a is indicated by the arrow R pointing towards the Fig. 6, Fig. 7, Fig. 8 to Fig. 9 is displayed, and the rotating element 24 and the rotor 31 rotate in the Fig. 6 in the counterclockwise direction.

[0042] The turbo compressor 10 has a pair of axial foil bearings 30, 30 and a pair of radial foil bearings 40, 40. The pair of axial foil bearings 30, 30 supports the third supported section 24d of the rotating element 24 in the axial direction of the rotating shaft 24a such that the third supported section 24d is rotatable relative to the housing 11 (i.e., to the second disk 16). The pair of radial foil bearings 40, 40 supports the first supported section 24b and the second supported section 24c of the rotating element 24 in a direction perpendicular to the axial direction of the rotating shaft 24a such that the first supported section 24b and the second supported section 24c are rotatable relative to the housing 11.

[0043] The pair of axial foil bearings 30, 30 is provided in the axial bearing receiving chamber S2. The axial foil bearings 30, 30 hold the third supported section 24d as the pressure ring between them. The axial foil bearings 30, 30 are oriented towards the third supported section 24d in the axial direction of the rotating shaft 24a. One of the axial foil bearings 30, 30 is arranged adjacent to the first end section 24e of the rotating shaft 24a with respect to the third supported section 24d. The other of the axial foil bearings 30, 30 is arranged adjacent to the second end section 24f of the rotating shaft 24a with respect to the third supported section 24d.

[0044] As from the Fig. As can be seen in Figure 2, the opposing end surfaces of the third supported section 24d serve as bearing contact surfaces 241d, 241d. One of the bearing contact surfaces 241d, 241d adjacent to the first end section 24e of the rotating shaft 24a is axially supported by one of the axial foil bearings 30, 30. The other bearing contact surface 241d, 241d adjacent to the second end section 24f of the rotating shaft 24a is axially supported by the other of the axial foil bearings 30, 30.

[0045] As from the Fig. 2 and Fig. As can be seen in Figure 5, the second disk 16 has a bearing element 60 that is integrally formed with the end surface 16b of the second disk 16 adjacent to the fourth disk 29. The bearing element 60 projects axially from the central section of the second disk 16 to the third supported section 24d. The shaft insertion bore 16a also extends continuously through the central section of the bearing element 60. The bearing element 60 is located within the central bore 29a of the fourth disk 29.

[0046] The bearing part 60 has six grooves extending from an end surface 60a of the bearing part 60, which rises in the axial direction towards the third supported section 24d. In other words, six passages 61 are formed in the end surface 60a of the bearing part 60, each having the form of a groove. Each of the passages 61 serves as the groove of the present invention. The passages 61 are spaced equally apart from one another in a circumferential direction of the rotating shaft 24a. Each of the passages 61 extends to an outer edge surface 60b of the bearing part 60. Specifically, the passages 61 have an opening 61a that is open towards the outer edge surface 60b of the bearing part 60 (see the Fig. 6 and Fig. 7) The passage 61 extends from the outer edge surface 60b of the bearing part 60 in a radial direction towards the axis of the rotating shaft 24a. The end of the passage 61 on the inner edge of the bearing part 60 extends to a location near the shaft insertion bore 16a.

[0047] As from the Fig. As can be seen in Figure 2, one of the axial foil bearings 30, 30 is mounted on the end surface 60a of the bearing part 60 of the second disk 16, and the other of the axial foil bearings 30, 30 is mounted on the bottom surface 15d of the recess 15c of the first disk 15. The other of the axial foil bearings 30, 30 can be mounted on a cover element, which is not shown, and the cover element can be attached to a bearing part with a screw and joined to the first disk 15.

[0048] As from the Fig. As can be seen from Figure 6, six corrugated sheets 32 are mounted on the end surface 60a of the bearing part 60, each having a disc-like shape, and are arranged around the shaft insertion bore 60a and evenly spaced from one another (i.e., with a gap between the adjacent sheets 32). Fig. As can be seen in Figure 8, each of the corrugated sheets 32 has opposite ends in the circumferential direction, and one of the opposite ends is attached to the end surface 60a of the bearing part 60 by welding. One end and the other end of the corrugated sheet 32 ​​in the circumferential direction are, in fact, a fixed end 32a and a free end 32b, respectively. Conversely, the other end and the one end of the corrugated sheet 32 ​​in the circumferential direction can be a fixed end or a free end, respectively.

[0049] Each of the corrugated sheets 32 has an approximately fan-shaped outline in a planar view. The corrugated sheet 32 ​​is made of an elastic thin metal disc, such as a stainless steel disc, and has a corrugated shape in which a plurality of projections 32c and a plurality of recesses 32d are arranged alternately in the circumferential direction of the rotating shaft 24a. A plurality of ridges 32e of the projections 32c are arranged in the circumferential direction of the rotating shaft 24a. The projections 32c of the corrugated sheets 32 extend towards the third supported section 24d in order to come into contact with a plurality of uppermost sheets 33, thereby elastically supporting the uppermost sheets 33.

[0050] As from the Fig. As can be seen in Figure 7, in this embodiment the six uppermost foils 33, each having a disc-like shape, are mounted on the end surface 60a of the bearing part 60 and arranged around the shaft insertion bore 16a with a gap between the adjacent uppermost foils 33. As can be seen from the Fig. As can be seen in Figure 8, each of the uppermost sheets 33 has opposite ends in the circumferential direction. One of the opposite ends is a free end, and the other of the opposite ends is folded towards the bearing part 60 and attached to the distal section of the other end by welding to the end surface 60a of the bearing part 60. The other end and the one end of the uppermost sheet 33 in the circumferential direction are a fixed end 33a and a free end 33b, respectively. Each of the uppermost sheets 33 has an approximately fan-shaped outline in a top view. The uppermost sheets 33 are each made of an elastic thin metal disc, such as a stainless metal disc, and have a predetermined shape.

[0051] The uppermost sheets 33 are uniformly spaced from one another in the circumferential direction of the rotating shaft 24a to correspond to the corrugated sheets 32 and are elastically supported by the corrugated sheets 32. Each of the uppermost sheets 33 has one surface facing the third supported section 24d, which is the pressure ring, and the other surface that is elastically supported by the corresponding corrugated sheet 32. One surface of the uppermost sheet 33 serves as a bearing surface 33c, which is oriented axially towards the bearing contact surface 241d of the third supported section 24d.

[0052] The axial foil bearing 30 is mounted on the end face 60a of the bearing part 60 such that the position of each passage 61 corresponds to the position of the gap between the corresponding adjacent corrugated foils 32 and the position of the gap between the corresponding adjacent uppermost foils 33, and such that each passage 61 is oriented axially towards the third supported section 24d as the pressure ring. The corrugated foils 32 are uniformly spaced from one another in the circumferential direction of the rotating shaft 24a, while the six passages 61 are omitted, and the uppermost foils 33 are uniformly spaced from one another in the circumferential direction of the rotating shaft 24a, while the six passages 61 are omitted. The corrugated foils 32 and the uppermost foils 33 are mounted on the end face 60a of the bearing part 60, while the passages 61 are omitted.This enables the end surface 60a of the bearing part 60 to reliably receive the load of the corrugated sheets 32. Each of the passages 61 is arranged in a circumferential gap 32f. Each of the circumferential gaps 32f is arranged between the corrugated sheets 32 adjacent to one another in the circumferential direction of the rotating shaft 24a and extends in the radial direction that intersects the circumferential direction (see . Fig. 6) In the following description, the circumferential gaps 32f each represent a gap that is arranged between the corrugated sheets 32 adjacent to one another in the circumferential direction of the rotating shaft 24a and extends in a direction that intersects the circumferential direction.

[0053] In each of the circumferential gaps 32f, the passage 61 extends continuously from the outer edge edges of the adjacent corrugated sheets 32 to the vicinity of the inner edge edges of the corrugated sheets 32. Each of the passages 61 extends over almost the entire length of the corrugated sheets 32 in the radial direction, such that, on an imaginary plane perpendicular to the axial direction of the rotating shaft 24a, the passage 61 overlaps most of the corresponding circumferential gaps 32f in the radial direction that intersects the circumferential direction.

[0054] Similar to the one axial foil bearing 30 mounted on the bearing part 60, the other axial foil bearing 30 mounted on the recess 15c has the six corrugated foils 32 and the six uppermost foils 33.

[0055] One of the radial foil bearings 40, 40 is provided in the first bearing section 20, and the other of the radial foil bearings 40, 40 is provided in the second bearing section 22. In the first bearing section 20, the first supported section 24b of the rotating element 24 is rotatably supported by one of the radial foil bearings 40, 40. The first supported section 24b has an outer edge surface that serves as a radial bearing contact surface 24d, which is supported by one of the radial foil bearings 40, 40 in the direction perpendicular to the axial direction of the rotating shaft 24a. In the second bearing section 22, the second supported section 24c of the rotating element 24 is rotatably supported by the other of the radial foil bearings 40, 40.The second supported section 24c has an outer edge surface which also serves as the radial bearing contact surface 24c, which is supported by the other of the radial foil bearings 40, 40 in the direction perpendicular to the axial direction of the rotating shaft 24a.

[0056] Since both of the radial foil bearings 40, 40 have the same configuration, the following description will focus on one of the radial foil bearings 40, 40 and will not elaborate on the other of the radial foil bearings 40, 40.

[0057] The radial foil bearing 40 has a radial corrugated foil 42 and a radial top foil 43. The radial corrugated foil 42 and the radial top foil 43 are each formed from an elastic thin metal disc, such as a stainless steel disc, and each has a predetermined approximately cylindrical shape. The radial corrugated foil 42 and the radial top foil 43 each have opposite ends in the circumferential direction of the rotating shaft 24a. One of the opposite ends of the radial corrugated foil 42 and one of the opposite ends of the radial top foil 43 are free ends, and the other of the opposite ends of the radial corrugated foil 42 and the other of the opposite ends of the radial top foil 43 are folded outwards in the radial direction so that they are attached to the inner edge surface of the first bearing support section 20.One end and the other end of the radial corrugated foil 42 and the radial uppermost foil 43 in the circumferential direction are free ends and fixed ends, respectively.

[0058] The radial corrugated sheet 42 has a wave-like shape in which a plurality of projections, extending towards the radial top sheet 43, have raised areas arranged in the circumferential direction of the rotating shaft 24a. The radial corrugated sheet 42 also has depressions alternating with the projections and elastically supports the radial top sheet 43 by means of the depressions supported by the projections through the first bearing section 20. One of the opposing surfaces of the radial top sheet 43 is elastically supported by the radial corrugated sheet 42, and the other of the opposing surfaces of the radial top sheet 43 serves as a radial bearing surface 43a (see Fig. 2 and Fig. 3), which is directed in the radial direction to the radial bearing contact surface 24g.

[0059] As from the Fig. As can be seen in Figure 8, the axial foil bearings 30, 30 support the rotating shaft 24a with the bearing surface 33c of each uppermost foil 33, which touches the bearing contact surface 241d of the third supported section 24d (that is, at a low rotational speed), until the rotational speed of the rotating shaft 24a reaches a floating speed at which the third supported section 24d, serving as the pressure ring, allows the axial foil bearings 30, 30 to float.

[0060] As from the Fig. As can be seen in Figure 9, when the rotational speed of the rotating shaft 24a reaches the floating speed (i.e., at a high rotational speed), the pressure of the fluid film generated between the uppermost foil 33 and the third supported section 24d causes the axial foil bearings 30, 30 to float with an elastic deformation of the corrugated foil 32. Accordingly, the axial foil bearings 30, 30 support the rotating shaft 24a without touching the third supported section 24d.

[0061] The radial foil bearings 40, 40 support the rotating shaft 24a, with the radial bearing surfaces 43a of the radially uppermost foil 43 contacting the radial bearing contact surface 24g of the first supported section 24b and the radial bearing surface 24d of the second supported section 24c until the rotational speed of the rotating shaft 24a reaches a floating speed at which the first supported section 24b and the second supported section 24c of the rotating shaft 24a float away from the radial foil bearings 40, 40. When the rotational speed of the rotating shaft 24a reaches the floating speed, pressure from the fluid film generated between the radially uppermost foil 43 and the first and second supported sections 24b, 24c causes the first and second supported sections 24b, 24c to float away from the radial foil bearings 40, 40. Accordingly, the radial foil bearings 40, 40 support the rotating shaft 24a without touching the first and second supported sections 24b, 24c.

[0062] As from the Fig. 1, Fig. 2 to Fig. As can be seen in Figure 3, the housing 11 has a cooling passage 50. Cooling air, serving as the fluid of the present invention, flows through the cooling passage 50. The cooling passage 50 is formed by the second disk 16, the fourth disk 29, the first disk 15, the motor housing 12, and the third disk 17. The cooling passage 50 has a first passage 51 and a second passage 52. The passages 61 form part of the cooling passage 50.

[0063] The first passage 51 is formed in the second disk 16 and the fourth disk 29. The first passage 51 has an inlet 51a, which also serves as the opening of the connecting groove 29c on the outer edge surface of the fourth disk 29. The inlet 51a of the first passage 51 is connected to the feed passage L1 via the branch passage L3. The first passage 51 is connected to the motor chamber S1 via the connecting groove 29c and the central bore 29a of the fourth disk 29, the axial bearing receiving chamber S2, and one of the radial foil bearings 40.

[0064] The second passage 52 is formed in the third disk 17. The second passage 52 has an outlet 52a formed in a side surface of the third disk 17. The second passage 52 is connected to the motor chamber S1 through the other of the radial foil bearings 40, 40.

[0065] The air flowing through the supply passage L1 to the fuel cell stack partially flows through the branch passage L3 into the first passage 51. The air in the first passage 51 was cooled by the intercooler 110 while flowing through the branch passage L3 to serve as the cooling air.

[0066] The cooling air flows through the inlet 51a into the first passage 51 and reaches the central bore 29a through the connecting groove 29c of the fourth disk 29. The cooling air reaching the central bore 29a primarily cools one of the axial foil bearings 30. The cooling air reaching the central bore 29a through the connecting groove 29c flows from the openings 61a into the passages 61, while flowing circumferentially into the central bore 29a. The cooling air flows radially in the passages 61 from the outer edge to the inner edge of the bearing part 60, and then flows out of each passage 61 located in the corresponding circumferential gap 32f between the corrugated foils 32, which are adjacent to one another in the circumferential direction of the rotating shaft 24a and extend radially.Since the passage 61 is directed towards the third supported section 24d, which is the pressure ring, the cooling air flowing from the passage 61 into the circumferential gap 32f cools the corrugated sheets 32 and the uppermost sheets 33, while, due to a centrifugal force from the third supported section 24b, it flows from the inner edge in the direction intersecting the circumferential direction to the outer edge. Similarly, the cooling air flowing in the circumferential direction from the inner edge to the outer edge effectively cools the uppermost sheets 33.

[0067] After cooling one of the axial foil bearings 30, 30, the cooling air flows radially outwards from the third supported section 24b and flows from the outer edge to the inner edge of the other axial foil bearing 30, 30 to cool the inner axial foil bearing 30. A portion of the cooling air flowing into the central bore 29a connecting groove 29c directly cools the other axial foil bearing 30, 30 without cooling the first of the axial foil bearings 30, 30.

[0068] After the cooling air has flowed through the axial bearing mounting chamber S2, it flows axially from one side to the other into one of the radial foil bearings 40, 40 to cool it. The cooling air then flows through one of the radial foil bearings 40, 40 and into the motor chamber S1.

[0069] The air in the motor chamber S1, for example, flows through a gap between the rotor 31 and the stator 35, and the air then flows into the second passage 53 through the other of the radial foil bearings 40, 40 and is discharged from the outlet 52a.

[0070] Accordingly, the cooling air flows through the cooling passage 50 to directly cool the electric motor 18, the pair of axial foil bearings 30, 30 and the pair of radial foil bearings 40, 40.

[0071] At low rotational speeds of the shaft, the rotating pressure ring is supported by the uppermost films, with the uppermost films in contact with the pressure ring. The sliding of the pressure ring against the uppermost films generates heat. At high rotational speeds of the shaft, the fluid film between the pressure ring and each of the uppermost films is sheared, generating heat. The uppermost films are each formed from an elastic thin disk with low heat capacity. Accordingly, the axial film bearings 30, 30 and the radial film bearings 40, 40 can exhibit a problem with respect to the thermal resistance of the uppermost films 33 and the radial uppermost films 43.In this respect, the cooling air flows into the turbo compressor in the axial foil bearings 30, 30 and the radial foils 40, 40, so that the cooling air cools the uppermost foils 33 and the radial uppermost foils 43, thereby solving the problem regarding the thermal resistance of the uppermost foils 33 and the radial uppermost foils 43.

[0072] In this turbo compressor 10, it is desirable to actively cool one of the axial foil bearings 30, 30, since the axial foil bearing 30 adjacent to the first impeller 25 is subject to a particularly high axial load.

[0073] In this respect, the turbo compressor 10 has passages 61. Each passage 61 is arranged in the corresponding circumferential gap 32f of one of the axial foil bearings 30, 30 and extends from the outer edge edges of the corrugated foils 32 to the vicinity of the inner edge edges of the corrugated foils 32, so that the cooling air is introduced into the passage 61. Accordingly, the one of the axial foil bearings 30, 30, which is subject to a large axial load, is actively cooled.

[0074] Furthermore, in the turbo compressor 10, the gap between the shaft insertion bore 16a of the second disk 16 and the rotating shaft 24a is sealed by the first sealing element 27, and the second disk 16 separates the first impeller chamber 13b, the compression chamber, from the axial bearing receiving chamber S2, the charge chamber. The passage 61 for cooling one of the axial foil bearings 30 is not formed through the second disk 16 in the direction of its thickness, but rather the passage 61 is a groove-shaped passage formed in the end face 60a of the bearing part 60, which is integrally formed with the second disk 16.This configuration eliminates the need for an additional partition that defines the first impeller chamber 13b in the opposite space formed on the opposite side of the axial bearing receiving chamber S2 with reference to the second disk 16, thereby preventing an increase in the size of the turbo compressor 10 in the axial direction.

[0075] This configuration therefore makes it possible to effectively cool one of the axial foil bearings 30, 30, which is particularly subject to a large shear load, without causing an increase in the size of the turbo compressor 10 in the axial direction.

[0076] In this turbo compressor 10, the passage 61 is arranged in each circumferential gap 32f of one axial foil bearing 30. Each passage 61 extends over almost the entire length of the corrugated foil 32 in the radial direction. This enables the cooling air from the passages 61 to successfully cool almost the entire top foil 33 of one of the axial foil bearings 30.

[0077] As in the Fig. 10 and Fig. As shown in Figure 11, this turbo compressor has the passages 61 formed in the bearing part 60, and each passage 61 has a shape that is modified from the shape of each passage 61 of the turbo compressor 10 according to the first embodiment.

[0078] Each passage 61 has a pair of groove side surfaces 61b, 61c, each oriented towards the other in the circumferential direction of the rotating shaft 24a to define the passage 61, a bottom surface 61d, and an opening edge 61e. The groove side surface 61c, which advances in the direction of rotation R of the rotating shaft 24a, is inclined in the direction of rotation R at an angle θ1 from the bottom surface 61d to the opening edge 61e as it extends in the axial direction.

[0079] Accordingly, the cooling air in the passage 61 receives a rotational force from the third supported section 24d rotating in the direction of rotation R and flows uniformly along the inclined groove side surface 61c advancing in the direction of rotation R into one of the axial foil bearings 30, 30.

[0080] Other elements and actuations of this compressor are the same as those of the turbo compressor 10 according to the first embodiment.

[0081] As in the Fig. As shown in Figure 12, this turbo compressor has the passages 61 formed in the bearing part 60, and each passage 61 has a shape that is modified from the shape of each passage 61 of the turbo compressor 10 according to the first embodiment. With this modification, the shapes of the corrugated sheets 32 and the uppermost sheets 33 of one of the axial sheet bearings 30, 30 are modified from the shapes of the corrugated sheets 32 and the uppermost sheets 33 of one of the axial sheet bearings 30, 30 of the turbo compressor 10 according to the first embodiment.

[0082] In the third embodiment, each passage 61 is inclined at an angle of θ2 in the direction of rotation R of the rotating shaft 24a from the outer edge to the inner edge of the bearing part 60, while extending in the radial direction.

[0083] With this modification of the passage 61, the shapes of the corrugated sheets 32 and the top sheets 33 of one of the axial foil bearings 30, 30 are modified from the shapes of the corrugated sheets 32 and the top sheets 33 of one of the axial foil bearings 30, 30 of the turbo compressor 10 according to the first embodiment. Specifically, the corrugated sheets 32 and the top sheets 33 are mounted on the bearing part such that the position of each passage 61 corresponds to the position of the gap between the corresponding adjacent corrugated sheets 32 and the position of the gap between the corresponding adjacent top sheets 33, and such that each passage 61 is directed axially towards the third supported section 24b. The corrugated sheets 32 and the top sheets 33 are mounted on the end face 60a of the bearing part 60, while the passages 61 are avoided. This enables the end surface 60a of the bearing part 60 to reliably receive the loads of the corrugated sheets 32.

[0084] Accordingly, the cooling air in the passage 61 receives a rotational force from the third supported section 24d, which rotates in the direction of rotation R, and flows uniformly from the outer edge to the inner edge of the bearing part 60 in the direction intersecting the circumferential direction into the passage 61.

[0085] Other elements and actuations of this compressor are the same as those of the turbo compressor 10 according to the first embodiment.

[0086] Although the present invention has been described based on first to third embodiments, the present invention is not limited to the first to third embodiments, but can be modified within the scope of the present invention.

[0087] According to the first to third embodiments, the axial foil bearings 30 have six corrugated foils 32 and six top foils 33, but the number of corrugated foils 32 and the number of top foils 33 are not limited as long as the number of corrugated foils 32 equals the number of top foils 33 and is greater than 1. The corrugated foils can be formed integrally with each other by a ring-shaped element to form a disk shape. The top foils can also be formed integrally with each other by a ring-shaped element to form a disk shape.

[0088] According to the first to third embodiments, the passage 61 is arranged in each circumferential gap 32f, but the present invention is not limited thereto. Each passage 61 can be arranged in only some of the circumferential gaps 32f.

[0089] According to the first to third embodiments, the end of the passage 61 extends along the inner edge of the layer 60 to a proximity of the inner edge of the corresponding corrugated sheet 32, but the present invention is not limited thereto. The end of the passage 61 on the inner edge can extend, for example, over half the length of the corrugated sheet 32 ​​in the radial direction.

[0090] According to the first to third embodiments, the second disk 16 is formed integrally with the bearing part 60 as the partition. However, the second disk 16 can be formed separately from the bearing part 60.

[0091] According to the first to third embodiments, the second disk 16 is configured as a partition separate from the fourth disk 29. However, the second disk 16 can be formed integrally with the fourth disk 29. In this configuration, instead of the connecting groove 29c, a through-hole can be formed through the integral part formed from the second disk 16 and the fourth disk 29, from the outer edge surface of the integral part to the inner edge surface of the central hole 29a.

[0092] The second embodiment can be combined with the third embodiment. This combination enables more effective cooling of the uppermost foils 33 of one of the axial foil bearings 30, 30.

[0093] The present invention is applicable to a fluid machine for a fuel cell system such as an air compressor.

Claims

[1] Turbofluid engine (10) with: a rotating shaft (24a) configured to rotate an axis of the rotating shaft (24a); a pressure ring (24d) having a disk-like shape and extending from an edge surface (240a) of the rotating shaft (24a) in a radial direction of the rotating shaft (24a), wherein the pressure ring (24d) is rotatable together with the rotating shaft (24a); an actuating part (25) which is configured to rotate together with the rotary shaft (24a) to compress and discharge a fluid; a housing (11) that accommodates the rotating shaft (24a), the pressure ring (24d) and the actuating part (25); a partition (16) having an insertion hole (16a) formed through the partition (16) and through which the rotating shaft (24a) is inserted, wherein the partition (16) separates an interior of the housing (11) into a compression chamber (13b) in which the actuating part (25) is received and a storage chamber (S2) in which the pressure ring (24d) is received; and a foil bearing (30) which supports the pressure ring (24d) in an axial direction of the rotating shaft (24a) such that the pressure ring (24d) is rotatable relative to the partition (16), the partition (16) has a bearing part (60) which has an end surface (60a) that rises in the axial direction towards the pressure ring (24d), characterized by , that the bearing part (60) has a groove (61) which is formed in the end surface (60a) and extends in the radial direction to an outer edge surface (60b) of the bearing part (60), The film support (30) has: a plurality of corrugated films (32), each formed from an elastic thin disk having a corrugated shape and mounted on the end face (60a); and a plurality of top films (33), each formed from an elastic thin disk, wherein the corrugated films (32) are arranged around the insertion hole (16a) with a gap (32f) between the adjacent corrugated films (32), wherein the top films (33) are arranged around the insertion hole (16a) with a gap between the adjacent top films (33), and each has one surface (33c) facing the pressure ring (24d), and the other surface is elastically supported by the corresponding corrugated film (32), and the foil bearing (30) is mounted on the bearing part (60) such that a position of the groove (61) corresponds to a position of the gap between the corrugated foils (32) and a position of the gap between the uppermost foils (33), and such that the groove (61) is directed in the axial direction towards the pressure ring (24d), the groove (61) is not connected to the insertion hole (16a). [2] Turbofluid machine (10) according to claim 1, characterized by , that the groove (61) has a pair of groove side surfaces (61b, 61c) which are each oriented towards each other in a circumferential direction of the rotating shaft (24a) to define the groove (61), a bottom surface (61d) and an opening edge (61e), and one of the groove side surfaces (61b, 61c) which advances in a direction of rotation (R) of the rotating shaft (24a) is inclined in the direction of rotation (R) from the bottom surface (61d) to the opening edge (61e) while extending in the axial direction. [3] Turbofluid machine (10) according to claim 1 or 2, characterized by , that the groove (61) is inclined in a direction of rotation (R) from an outer edge side to an inner edge side of the bearing part (60) while extending in the radial direction.

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