Centrifugal compressor

Abstract

The present invention is provided with: an air return flow path (74) which extends along a cooling water flow path (60) and which returns air after cooling a motor (20), a first radial bearing (53) and the like to a first suction path (33); and air which extends along the cooling water flow path (60), separates the air return flow path (74) from the cooling water flow path (60), and flows through the air return flow path (74), and air which flows through the cooling water flow path (60). And a partition wall (85) for heat exchange of the flowing cooling water. The air flowing in the air backflow flow path (74) dissipates heat to the cooling water flowing in the cooling water flow path (60) through the partition wall (85).

Description

Technical Field

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

[0002] The centrifugal compressor includes a rotating shaft, a bearing, a motor, an impeller, and a housing. The bearing supports the rotating shaft so that it can rotate. The motor rotates the rotating shaft. The impeller compresses the air by rotating integrally with the rotating shaft. The housing includes an impeller chamber and a motor chamber. The impeller chamber accommodates the impeller. The motor chamber accommodates the motor. In addition, the centrifugal compressor includes an intake passage. The intake passage takes air into the impeller chamber.

[0003] In such a centrifugal compressor, in order to improve the durability of the centrifugal compressor, it is desirable to cool the motor and the bearings. Therefore, for example, as in Patent Document 1, the centrifugal compressor sometimes has a cooling water flow path and an air supply flow path. The cooling water flow path is used to flow cooling water for cooling the motor and the bearings. The air supply flow path supplies a portion of the air compressed by the impeller to the motor and the bearings. Thus, the motor and the bearings are cooled by the cooling water flowing in the cooling water flow path, and the motor and the bearings are also cooled by the air supplied from the air supply flow path to the motor and the bearings. The air supplied from the air supply flow path to the motor and the bearings and cooled is discharged to the outside of the casing.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-202588 Summary of the invention

[0007] Problems to be solved by the invention

[0008] For example, the amount of pressure loss caused by the length and diameter of the piping is different for each system that includes the centrifugal compressor as a whole. Therefore, the discharge pressure discharged to the outside of the casing, which is the discharge destination of the air, is also different for each system that includes the centrifugal compressor as a whole. Therefore, if the centrifugal compressor is mounted on different systems, the difference between the pressure of the air compressed and discharged by the impeller, that is, the discharge pressure and the discharge pressure discharged to the outside of the casing is different for each system. If the difference between the discharge pressure and the discharge pressure is different, the flow rate of air supplied from the air supply flow path to the motor and the bearing is also different. Here, since the higher the discharge pressure, the smaller the difference between the discharge pressure and the discharge pressure, the flow rate of air supplied from the air supply flow path to the motor and the bearing will decrease. As a result, it is sometimes difficult to use air to cool the motor and the bearing stably.

[0009] Therefore, for example, it is conceivable to allow the air after cooling the motor and the bearings to flow back to the suction passage immediately before the impeller chamber. The pressure of the air flowing in the suction passage is the pressure of the air sucked into the impeller chamber, that is, the suction pressure. The suction pressure immediately before the impeller chamber is stable because it is easy to uniquely determine according to the specifications of the centrifugal compressor. Therefore, even when the centrifugal compressor is installed in different systems, the difference between the discharge pressure and the suction pressure is difficult to change, so the flow rate of air supplied from the air supply flow path to the motor and the bearings can be made the same regardless of the system. Therefore, the flow rate of air supplied from the air supply flow path to the motor and the bearings can be stabilized.

[0010] However, if the air after cooling the motor and the bearings is refluxed to the suction passage, the temperature of the air sucked from the suction passage into the impeller chamber will increase. If the temperature of the air sucked from the suction passage into the impeller chamber increases, the compression efficiency may deteriorate because the high-temperature air is compressed by the impeller. Therefore, in a centrifugal compressor, it is desired to stably cool the motor and the bearings with air while avoiding deterioration of the compression efficiency.

[0011] Means for solving problems

[0012] A centrifugal compressor for solving the above-mentioned problems comprises: a rotating shaft; a bearing for rotatably supporting the rotating shaft; a motor for rotating the rotating shaft; an impeller for compressing air by rotating integrally with the rotating shaft; a casing having an impeller chamber for accommodating the impeller and a motor chamber for accommodating the motor; an intake passage for sucking air into the impeller chamber; a cooling water flow path for supplying cooling water for cooling the motor and the bearing; and an air supply flow path for supplying a portion of the air compressed by the impeller to the motor and the bearing. And to cool the motor and the bearings, the centrifugal compressor comprises: an air return flow path, which extends along the cooling water flow path and allows the air after cooling the motor and the bearings to flow back to the suction passage; and a partition wall, which extends along the cooling water flow path and separates the air return flow path from the cooling water flow path and performs heat exchange between the air flowing in the air return flow path and the cooling water flowing in the cooling water flow path, and the air flowing in the air return flow path dissipates heat to the cooling water flowing in the cooling water flow path via the partition wall.

[0013] Thus, the air after cooling the motor and the bearings flows back to the suction passage through the air return flow path. The pressure of the air flowing in the suction passage is the pressure of the air sucked into the impeller chamber, that is, the suction pressure. The suction pressure is stable because it is easy to be uniquely determined according to the specifications of the centrifugal compressor. Therefore, the pressure of the air compressed and discharged by the impeller, that is, the difference between the discharge pressure and the suction pressure, is difficult to change, and therefore, the flow rate of the air supplied from the air supply flow path to the motor and the bearings is difficult to change. Therefore, the flow rate of the air supplied from the air supply flow path to the motor and the bearings can be stabilized. As a result, the motor and the bearings can be stably cooled by air.

[0014] When the air after cooling the motor and the bearing flows back to the intake passage through the air return flow path, heat exchange is performed between the air flowing in the air return flow path and the cooling water flowing in the cooling water flow path through the partition wall. Here, the partition wall extends along the cooling water flow path. Therefore, the air flowing in the air return flow path efficiently dissipates heat to the cooling water flowing in the cooling water flow path through the partition wall. Thus, the air flowing in the air return flow path can be efficiently cooled by the cooling water flowing in the cooling water flow path. And, the air cooled by the cooling water flows back to the intake passage through the air return flow path. Therefore, even if the air after cooling the motor and the bearing flows back to the intake passage through the air return flow path, the temperature of the air sucked from the intake passage to the impeller chamber can be avoided from becoming high. Therefore, even if the air after cooling the motor and the bearing flows back to the intake passage through the air return flow path, it can be avoided that the high-temperature air is compressed by the impeller, and therefore, the deterioration of the compression efficiency can be avoided. According to the above, the motor and the bearing can be stably cooled by air while avoiding the deterioration of the compression efficiency.

[0015] In the above-mentioned centrifugal compressor, it may be that the casing has a partition wall that separates the impeller chamber from the motor chamber and is formed with an insertion hole for the rotating shaft to pass through, the cooling water flow path has a cooling water extension flow path formed on the partition wall and extending around the insertion hole, the air return flow path has an air extension flow path extending along the cooling water extension flow path inside the partition wall, the partition wall extends along the cooling water extension flow path and separates the air extension flow path from the cooling water extension flow path and performs heat exchange between the air flowing in the air extension flow path and the cooling water flowing in the cooling water extension flow path, and the air flowing in the air extension flow path dissipates heat to the cooling water flowing in the cooling water extension flow path via the partition wall.

[0016] The partition wall separating the impeller chamber from the motor chamber is a portion of the housing that is relatively close to the suction passage. In addition, the air extension passage extends along the cooling water extension passage formed in the partition wall. The air flowing in the air extension passage dissipates heat to the cooling water flowing in the cooling water extension passage via the partition wall. Therefore, at a portion of the housing that is relatively close to the suction passage, the air flowing in the air return passage can dissipate heat to the cooling water flowing in the cooling water passage via the partition wall, and then the air is returned to the suction passage via the air return passage. Therefore, the air can be returned to the suction passage while suppressing the cooling water flowing in the cooling water passage from being heated again as much as possible. As a result, even if the air after cooling the motor and the bearing is returned to the suction passage via the air return passage, it is easy to avoid the temperature of the air sucked from the suction passage to the impeller chamber from becoming high. Therefore, even if the air after cooling the motor and the bearing is returned to the suction passage via the air return passage, it is easy to avoid the high-temperature air being compressed by the impeller, and therefore, it is easy to avoid the deterioration of the compression efficiency.

[0017] In the above-mentioned centrifugal compressor, the partition wall may include: a first shell structure having a first recessed portion forming the cooling water extension flow path and extending around the insertion hole; a second shell structure having a second recessed portion forming the air extension flow path and extending around the insertion hole and having the partition wall, wherein the opening of the first recessed portion is closed by the partition wall and the cooling water extension flow path is demarcated together with the first recess; and a cover member, which closes the opening of the second recessed portion and demarcates the air extension flow path together with the second recess.

[0018] Thus, by closing the opening of the first recess of the first housing component by the partition wall of the second housing component, a cooling water extension flow path extending around the insertion hole can be formed. Furthermore, by closing the opening of the second recess of the second housing component by the cover member, an air extension flow path extending along the cooling water extension flow path can be formed. Furthermore, it can be configured so that the air flowing in the air extension flow path can dissipate heat to the cooling water flowing in the cooling water extension flow path via the partition wall.

[0019] In the above-mentioned centrifugal compressor, the partition wall may include: a first shell structure having a recessed portion forming the cooling water extension flow path and extending around the insertion hole; and a second shell structure, which closes the opening of the recessed portion and demarcates the cooling water extension flow path together with the recessed portion. The centrifugal compressor includes a pipe member passing through the inner side of the cooling water extension flow path and constituting the air extension flow path, and the wall portion of the pipe member passing through the inner side of the cooling water extension flow path constitutes the partition wall.

[0020] Thus, by closing the opening of the recess of the first housing component with the second housing component, a cooling water extension flow path extending around the insertion hole can be formed. Furthermore, by passing the pipe member inside the cooling water extension flow path, the air extension flow path extending along the cooling water extension flow path can be formed by the pipe member. Furthermore, the wall portion of the portion of the pipe member passing through the inside of the cooling water extension flow path forms a partition wall. Thus, it can be configured so that the air flowing in the air extension flow path can dissipate heat to the cooling water flowing in the cooling water extension flow path via the partition wall.

[0021] In the above-mentioned centrifugal compressor, it may be that the impeller includes: a first impeller that compresses air; and a second impeller that compresses the air compressed by the first impeller, the impeller chamber includes: a first impeller chamber that accommodates the first impeller; and a second impeller chamber that accommodates the second impeller, the suction passage includes: a first suction passage that sucks air into the first impeller chamber; and a second suction passage that sucks air into the second impeller chamber, and the partition wall includes: a first partition wall that separates the first impeller chamber from the motor chamber; and a second partition wall, the first impeller chamber and the second impeller chamber. 2 partition walls separate the second impeller chamber from the motor chamber, the insertion hole includes: a first insertion hole formed in the first partition wall and for the rotating shaft to be inserted; and a second insertion hole formed in the second partition wall and for the rotating shaft to be inserted, the cooling water extension flow path is formed in the first partition wall and extends around the first insertion hole, the air extension flow path extends along the cooling water extension flow path inside the first partition wall, and the air return flow path allows the air after cooling the motor and the bearing to flow back to the first suction passage.

[0022] The heat of the air compressed by the first impeller is easily transferred to the first partition wall. In addition, the heat of the air compressed by the second impeller is easily transferred to the second partition wall. The second impeller compresses the air compressed by the first impeller, so the temperature of the air compressed by the second impeller is higher than the temperature of the air compressed by the first impeller. Therefore, the temperature of the second partition wall is higher than the temperature of the first partition wall. Therefore, the cooling water extension flow path is formed in the first partition wall. Therefore, for example, compared with the case where the cooling water extension flow path is formed in the second partition wall, the temperature of the cooling water flowing in the cooling water extension flow path can be maintained at a lower state. In addition, the air extension flow path extends along the cooling water extension flow path inside the first partition wall. Therefore, the air flowing in the air extension flow path dissipates heat to the cooling water flowing in the cooling water extension flow path via the partition wall. Since the temperature of the cooling water flowing in the cooling water extension flow path is maintained at a low state, the air flowing in the air extension flow path can dissipate heat efficiently to the cooling water flowing in the cooling water extension flow path via the partition wall.

[0023] Furthermore, the air return flow path returns the air after cooling the motor and the bearings to the first intake passage. The pressure of the air flowing in the first intake passage is lower than the pressure of the air flowing in the second intake passage. Therefore, for example, compared with the case where the air return flow path returns the air after cooling the motor and the bearings to the second intake passage, the pressure of the air at the return destination of the air is as low as possible, and therefore, it is easy to generate a difference between the discharge pressure and the pressure of the return destination of the air. Therefore, it is easy to ensure the flow rate of air supplied from the air supply flow path to the motor and the bearings, and therefore, the motor and the bearings can be stably cooled by air.

[0024] In the centrifugal compressor, the centrifugal compressor may include an intercooler for cooling the air flowing through the air supply flow path, and the air flowing through the air supply flow path may be supplied to the motor and the bearing after being cooled by the intercooler.

[0025] Thus, the air flowing in the air supply flow path can be cooled by the intercooler, so that a part of the air compressed by the impeller can be supplied from the air supply flow path to the motor and the bearing in a state of reduced temperature. Therefore, the motor and the bearing can be efficiently cooled by the air from the air supply flow path.

[0026] Effects of the Invention

[0027] According to the present invention, the motor and the bearing can be stably cooled by air while avoiding deterioration of compression efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view of the centrifugal compressor in the first embodiment.

[0029] Figure 2 This is a cross-sectional view showing a part of the centrifugal compressor in an enlarged manner.

[0030] Figure 3 It is a diagram showing the relationship between the cooling water extension flow path and the air extension flow path.

[0031] Figure 4 This is a cross-sectional view showing a part of the centrifugal compressor in the second embodiment in an enlarged manner.

[0032] Figure 5 It is a perspective view showing a pipe member. DETAILED DESCRIPTION

[0033] [First embodiment]

[0034] Below, according to Figure 1 to Figure 3A first embodiment in which a centrifugal compressor is embodied will be described. In addition, the centrifugal compressor of the embodiment described below is mounted on a fuel cell vehicle. The centrifugal compressor compresses air. The centrifugal compressor constitutes a part of the fuel cell system.

[0035] <Basic Structure of Centrifugal Compressor 10>

[0036] like Figure 1 As shown, the centrifugal compressor 10 includes a housing 11. The housing 11 is made of a metal material, for example, aluminum. The housing 11 includes a motor housing 12, a first compressor housing 13, a second compressor housing 14, a first plate 15, a second plate 16, a third plate 17, and a fourth plate 18.

[0037] The motor housing 12 extends in a cylindrical shape. The first plate 15 is connected to the end of one opening side of the motor housing 12. The first plate 15 closes the opening of one side of the motor housing 12. The second plate 16 is connected to the end of the other opening side of the motor housing 12. In addition, the motor housing 12, the first plate 15, and the second plate 16 define a motor chamber 19. Therefore, the housing 11 has the motor chamber 19.

[0038] The centrifugal compressor 10 includes a motor 20 . The motor 20 is housed in the motor chamber 19 . Therefore, the motor chamber 19 houses the motor 20 . The motor housing 12 surrounds the motor 20 .

[0039] The centrifugal compressor 10 includes a first bearing holding portion 21. The first bearing holding portion 21 protrudes from the center portion of the first plate 15 into the motor chamber 19. Therefore, the first plate 15 includes the first bearing holding portion 21. The first bearing holding portion 21 is cylindrical.

[0040] like Figure 2 As shown, an engaging recess 22 and a chamber forming recess 23 are formed on the end surface 15a of the first plate 15 on the opposite side to the motor housing 12. The engaging recess 22 and the chamber forming recess 23 are in the shape of circular holes. The hole diameter of the engaging recess 22 is larger than the hole diameter of the chamber forming recess 23. The chamber forming recess 23 is formed on the bottom surface of the engaging recess 22. The inner side of the first bearing holding portion 21 passes through the first plate 15 and opens on the bottom surface of the chamber forming recess 23. The axis of the chamber forming recess 23 coincides with the axis of the first bearing holding portion 21.

[0041] The third plate 17 is annular. The third plate 17 is mounted on the first plate 15 in a state where it is inserted into the fitting recess 22. The hole diameter of the third plate 17 is the same as the hole diameter of the chamber forming recess 23. The inner side of the third plate 17 is connected to the inner side of the chamber forming recess 23. The end surface 17a of the third plate 17 on the opposite side to the motor housing 12 is located on the same plane as the end surface 15a of the first plate 15.

[0042] The fourth plate 18 is connected to the end surface 15a of the first plate 15. A first insertion hole 24 is formed in the central portion of the fourth plate 18. The first insertion hole 24 is communicated with the inner side of the third plate 17. The axis of the first insertion hole 24 coincides with the axis of the third plate 17, the axis of the chamber forming recess 23, and the axis of the first bearing holding portion 21. Furthermore, a thrust bearing accommodation chamber 25 is defined by the chamber forming recess 23 of the first plate 15, the third plate 17, and the fourth plate 18. The thrust bearing accommodation chamber 25 is communicated with the inner side of the first bearing holding portion 21. In addition, the thrust bearing accommodation chamber 25 is communicated with the first insertion hole 24.

[0043] like Figure 1 As shown, the centrifugal compressor 10 includes a second bearing holding portion 26. The second bearing holding portion 26 protrudes from the center portion of the second plate 16 into the motor chamber 19. Therefore, the second plate 16 includes the second bearing holding portion 26. The second bearing holding portion 26 is cylindrical.

[0044] A second insertion hole 27 is formed in the center of the second plate 16. The second insertion hole 27 communicates with the inside of the second bearing holding portion 26. The axis of the second insertion hole 27 coincides with the axis of the second bearing holding portion 26.

[0045] like Figure 2 As shown, the first compressor housing 13 is a cylindrical shape having a first suction port 28 in the shape of a circular hole for sucking air. The first compressor housing 13 is connected to the end surface 18a of the fourth plate 18 on the opposite side to the first plate 15 in a state where the axis of the first suction port 28 coincides with the axis of the first insertion hole 24. The first suction port 28 opens at the end surface 13a of the first compressor housing 13 on the opposite side to the fourth plate 18.

[0046] The centrifugal compressor 10 includes a first impeller chamber 29, a first discharge chamber 30, and a first diffuser flow path 31. The first impeller chamber 29, the first discharge chamber 30, and the first diffuser flow path 31 are formed between the first compressor housing 13 and the end surface 18a of the fourth plate 18. Therefore, the housing 11 has the first impeller chamber 29. The first plate 15, the third plate 17, and the fourth plate 18 constitute a first partition wall that separates the first impeller chamber 29 from the motor chamber 19. The first impeller chamber 29 is connected to the first suction port 28. The first discharge chamber 30 extends around the first impeller chamber 29 around the axis of the first suction port 28. The first diffuser flow path 31 connects the first impeller chamber 29 with the first discharge chamber 30. The first impeller chamber 29 is connected to the first insertion hole 24.

[0047] The centrifugal compressor 10 includes a first suction pipe 32. The first suction pipe 32 is connected to the first suction port 28. The first suction pipe 32 is fixed to the end surface 13a of the first compressor housing 13. Air purified by an air filter (not shown) flows in the first suction pipe 32. The air passing through the first suction pipe 32 is sucked into the first impeller chamber 29 through the first suction port 28. Therefore, the first suction pipe 32 and the first suction port 28 constitute a first suction passage 33 for sucking air into the first impeller chamber 29. The centrifugal compressor 10 includes a first suction passage 33.

[0048] like Figure 1 As shown, the second compressor housing 14 is cylindrical and has a second inlet port 34 in the shape of a circular hole for sucking air. The second compressor housing 14 is connected to the end surface of the second plate 16 on the opposite side to the motor housing 12 in a state where the axis of the second inlet port 34 coincides with the axis of the second insertion hole 27. The second inlet port 34 opens at the end surface of the second compressor housing 14 on the opposite side to the second plate 16.

[0049] The centrifugal compressor 10 includes a second impeller chamber 35, a second discharge chamber 36, and a second diffuser flow path 37. The second impeller chamber 35, the second discharge chamber 36, and the second diffuser flow path 37 are formed between the second compressor housing 14 and the second plate 16. Therefore, the housing 11 has the second impeller chamber 35. The second plate 16 constitutes a second partition wall that separates the second impeller chamber 35 from the motor chamber 19. The second impeller chamber 35 is connected to the second suction port 34. The second discharge chamber 36 extends around the second impeller chamber 35 around the axis of the second suction port 34. The second discharge chamber 36 is connected to the fuel cell stack 39 via a supply pipe 38. The second diffuser flow path 37 connects the second impeller chamber 35 with the second discharge chamber 36. The second impeller chamber 35 is connected to the second insertion hole 27.

[0050] The centrifugal compressor 10 includes a second suction pipe 40. A first end of the second suction pipe 40 is connected to the first discharge chamber 30. A second end of the second suction pipe 40 is connected to the second suction port 34. Air from the first discharge chamber 30 flows in the second suction pipe 40. And, the air passing through the second suction pipe 40 is sucked into the second impeller chamber 35 through the second suction port 34. Therefore, the second suction pipe 40 and the second suction port 34 constitute a second suction passage 41 for sucking air into the second impeller chamber 35. The centrifugal compressor 10 includes a second suction passage 41.

[0051] The centrifugal compressor 10 includes a rotating shaft 42. The rotating shaft 42 is accommodated in the housing 11. The first end of the rotating shaft 42 protrudes from the motor chamber 19 into the first impeller chamber 29 through the inner side of the first bearing retaining portion 21, the thrust bearing accommodating chamber 25, and the first insertion hole 24. Therefore, the first insertion hole 24 is an insertion hole formed in the first partition wall and through which the rotating shaft 42 is inserted. The second end of the rotating shaft 42 protrudes from the motor chamber 19 into the second impeller chamber 35 through the inner side of the second bearing retaining portion 26 and the second insertion hole 27. Therefore, the second insertion hole 27 is an insertion hole formed in the second partition wall and through which the rotating shaft 42 is inserted. The rotating shaft 42 crosses the motor chamber 19 in a state extending along the axis of the motor housing 12. The axial direction of the rotating shaft 42 coincides with the axial direction of the motor housing 12.

[0052] The centrifugal compressor 10 includes a support portion 43. The support portion 43 protrudes in an annular shape from the outer peripheral surface of the rotating shaft 42. The support portion 43 is in the shape of a disk. The support portion 43 is fixed to the outer peripheral surface of the rotating shaft 42 in a state of protruding in an annular shape from the outer peripheral surface of the rotating shaft 42 toward the radial outer side. Therefore, the support portion 43 and the rotating shaft 42 are separate bodies. The support portion 43 is arranged in the thrust bearing accommodation chamber 25. The support portion 43 rotates integrally with the rotating shaft 42.

[0053] The centrifugal compressor 10 includes a first sealing member 44. The first sealing member 44 is provided between the first insertion hole 24 and the rotating shaft 42. The first sealing member 44 suppresses leakage of air from the first impeller chamber 29 toward the motor chamber 19. The first sealing member 44 is, for example, a seal ring.

[0054] The centrifugal compressor 10 includes a second sealing member 45. The second sealing member 45 is provided between the second insertion hole 27 and the rotating shaft 42. The second sealing member 45 suppresses leakage of air from the second impeller chamber 35 toward the motor chamber 19. The second sealing member 45 is, for example, a seal ring.

[0055] The centrifugal compressor 10 includes a first impeller 46. The first impeller 46 is connected to the first end of the rotating shaft 42. The first impeller 46 is accommodated in the first impeller chamber 29. Therefore, the first impeller chamber 29 accommodates the first impeller 46. The first impeller 46 compresses the air sucked into the first impeller chamber 29 by rotating integrally with the rotating shaft 42. Therefore, the first impeller 46 is an impeller that compresses the air by rotating integrally with the rotating shaft 42. Therefore, the first impeller chamber 29 is an impeller chamber that accommodates the impeller.

[0056] The centrifugal compressor 10 includes a second impeller 47. The second impeller 47 is connected to the second end of the rotating shaft 42. The second impeller 47 is accommodated in the second impeller chamber 35. Therefore, the second impeller chamber 35 accommodates the second impeller 47. The second impeller 47 compresses the air sucked into the second impeller chamber 35 by rotating integrally with the rotating shaft 42. Therefore, the second impeller 47 is an impeller that compresses the air by rotating integrally with the rotating shaft 42. Therefore, the second impeller chamber 35 is an impeller chamber that accommodates the impeller. Therefore, the impeller chamber includes the first impeller chamber 29 and the second impeller chamber 35. The casing 11 has an impeller chamber. The impeller includes the first impeller 46 and the second impeller 47. The second impeller 47 compresses the air compressed by the first impeller 46.

[0057] The first suction passage 33 is a suction passage for sucking air into the first impeller chamber 29 as an impeller chamber. The second suction passage 41 is a suction passage for sucking air into the second impeller chamber 35 as an impeller chamber. Therefore, the suction passage includes the first suction passage 33 and the second suction passage 41. In this way, the centrifugal compressor 10 includes a suction passage for sucking air into the impeller chamber.

[0058] The first partition wall formed by the first plate 15, the third plate 17, and the fourth plate 18 is a partition wall that separates the impeller chamber from the motor chamber 19. The second partition wall formed by the second plate 16 is a partition wall that separates the impeller chamber from the motor chamber 19. Therefore, the partition wall includes the first partition wall and the second partition wall. Therefore, the housing 11 has a partition wall formed with an insertion hole. The insertion hole includes a first insertion hole 24 and a second insertion hole 27.

[0059] The motor 20 includes a cylindrical rotor 48 and a cylindrical stator 49. The rotor 48 is fixed to the rotating shaft 42. The stator 49 is fixed to the housing 11. The rotor 48 is arranged radially inside the stator 49 and rotates integrally with the rotating shaft 42. The rotor 48 includes a cylindrical rotor core 50 fixed to the rotating shaft 42 and a plurality of permanent magnets (not shown) provided on the rotor core 50. The stator 49 surrounds the rotor 48. The stator 49 includes a cylindrical stator core 51 and a coil 52. The stator core 51 is fixed to the inner circumferential surface of the motor housing 12. The coil 52 is wound around the stator core 51.

[0060] The rotating shaft 42 rotates integrally with the rotor 48 when a current flows from a battery (not shown) to the coil 52. Thus, the motor 20 rotates the rotating shaft 42. The motor 20 is disposed between the first impeller 46 and the second impeller 47 in the axial direction of the rotating shaft 42.

[0061] The centrifugal compressor 10 includes a first radial bearing 53. The first radial bearing 53 is cylindrical. The first radial bearing 53 is held by the first bearing holding portion 21. The first radial bearing 53 rotatably supports a portion of the rotating shaft 42 that is located closer to the first end of the rotating shaft 42 than the motor 20. Therefore, the first radial bearing 53 is a bearing that rotatably supports the rotating shaft 42.

[0062] The centrifugal compressor 10 includes a second radial bearing 54. The second radial bearing 54 is cylindrical. The second radial bearing 54 is held by the second bearing holding portion 26. The second radial bearing 54 rotatably supports a portion of the rotating shaft 42 that is located closer to the second end of the rotating shaft 42 than the motor 20. Therefore, the second radial bearing 54 is a bearing that rotatably supports the rotating shaft 42.

[0063] The first radial bearing 53 and the second radial bearing 54 rotatably support the rotating shaft 42 in the radial direction at positions on both sides of the rotating shaft 42 sandwiching the motor 20 in the axial direction of the rotating shaft 42. The “radial direction” refers to a direction orthogonal to the axial direction of the rotating shaft 42.

[0064] The centrifugal compressor 10 includes a thrust bearing 55. The thrust bearing 55 is accommodated in the thrust bearing accommodation chamber 25. Therefore, the thrust bearing accommodation chamber 25 accommodates the thrust bearing 55. The thrust bearing 55 supports the support portion 43 in a thrust direction so that it can rotate. Therefore, the thrust bearing 55 is a bearing that supports the rotating shaft 42 in a rotatable manner via the support portion 43. In addition, the "thrust direction" refers to a direction parallel to the axial direction of the rotating shaft 42.

[0065] The air sucked into the first impeller chamber 29 through the first suction pipe 32 and the first suction port 28 is sent to the first diffusion channel 31 while being accelerated by the rotation of the first impeller 46 and is pressurized through the first diffusion channel 31. Then, the air passing through the first diffusion channel 31 is discharged to the first discharge chamber 30. The air discharged to the first discharge chamber 30 is sucked into the second impeller chamber 35 through the second suction pipe 40 and the second suction port 34. The air sucked into the second impeller chamber 35 is sent to the second diffusion channel 37 while being accelerated by the rotation of the second impeller 47 and is pressurized through the second diffusion channel 37. Then, the air passing through the second diffusion channel 37 is discharged to the second discharge chamber 36. The air discharged to the second discharge chamber 36 is supplied to the fuel cell stack 39 through the supply pipe 38. Therefore, the centrifugal compressor 10 supplies air to the fuel cell stack 39. Oxygen contained in the air supplied to the fuel cell stack 39 contributes to power generation of the fuel cell stack 39 .

[0066] <Cooling water passage 60>

[0067] The centrifugal compressor 10 includes a cooling water flow path 60. The cooling water flow path 60 includes a first water path 61, a second water path 62, and a third water path 63. The first water path 61 passes through the interior of the motor housing 12. The first water path 61 extends in the axial direction of the motor housing 12 while extending in a spiral shape inside the motor housing 12, for example. A first end of the first water path 61 opens at an opening end surface on the first plate 15 side of the motor housing 12. A second end of the first water path 61 opens at an opening end surface on the second plate 16 side of the motor housing 12.

[0068] The second water channel 62 extends in a spiral shape inside the first plate 15 while penetrating the first plate 15 in the thickness direction and reaches the inside of the fourth plate 18. Specifically, the second water channel 62 extends in a spiral shape while penetrating a portion of the first plate 15 located outside the fitting recess 22. A first end of the second water channel 62 is connected to the first water channel 61. A second end of the second water channel 62 is closed inside the fourth plate 18.

[0069] The third water channel 63 extends spirally inside the second plate 16. A first end of the third water channel 63 is connected to the first water channel 61. A second end of the third water channel 63 is closed inside the second plate 16. In addition, the first water channel 61, the second water channel 62, and the third water channel 63 are schematically shown in the figure for convenience of explanation.

[0070] The cooling water flow path 60 has a cooling water inlet 64 and a cooling water outlet 65. The cooling water inlet 64 and the cooling water outlet 65 are formed in the motor housing 12. The cooling water from the cooling water inlet 64 flows into the first water path 61. The cooling water flowing into the first water path 61 flows through the second water path 62 and the third water path 63, and then is discharged from the cooling water outlet 65 to the outside of the housing 11.

[0071] The cooling water flowing through the first water passage 61 cools the motor case 12 . The heat generated from the stator core 51 is radiated to the motor case 12 . Thus, the stator core 51 is cooled. Therefore, the motor 20 is cooled by the cooling water flowing through the first water passage 61 .

[0072] The cooling water flowing in the second water passage 62 cools the first plate 15 and the fourth plate 18. The heat generated from the first radial bearing 53 is dissipated to the first plate 15. Thus, the first radial bearing 53 is cooled. The heat generated from the thrust bearing 55 is dissipated to the first plate 15 and the fourth plate 18. Thus, the thrust bearing 55 is cooled. Therefore, the first radial bearing 53 and the thrust bearing 55 are cooled by the cooling water flowing in the second water passage 62.

[0073] The cooling water flowing in the third water path 63 cools the second plate 16. The heat generated from the second radial bearing 54 is dissipated to the second plate 16. As a result, the second radial bearing 54 is cooled. Therefore, the second radial bearing 54 is cooled by the cooling water flowing in the third water path 63. In this way, the cooling water for cooling the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55 flows in the cooling water flow path 60.

[0074] <Air Supply Flow Path 70>

[0075] The centrifugal compressor 10 includes an air supply flow path 70. The air supply flow path 70 includes a first supply flow path 71 and a second supply flow path 72. The first supply flow path 71 branches from the middle of the second suction pipe 40. A first end of the first supply flow path 71 is connected to the second suction pipe 40. A second end of the first supply flow path 71 is connected to the thrust bearing accommodation chamber 25. Therefore, the first supply flow path 71 connects the second suction pipe 40 and the thrust bearing accommodation chamber 25.

[0076] The first supply flow path 71 includes a first piping portion 71a and a first hole portion 71b. The first piping portion 71a is disposed outside the housing 11. The first hole portion 71b is formed in the first plate 15. The first end of the first piping portion 71a is connected to the middle of the second suction piping 40. The inside of the first piping portion 71a is connected to the inside of the second suction piping 40. The second end of the first piping portion 71a is connected to the first end of the first hole portion 71b. The first piping portion 71a is connected to the first hole portion 71b. The second end of the first hole portion 71b is connected to the thrust bearing accommodation chamber 25. The first hole portion 71b is connected to the thrust bearing accommodation chamber 25.

[0077] The second supply flow path 72 branches from the middle of the first supply flow path 71. The first end of the second supply flow path 72 is connected to the first supply flow path 71. The second end of the second supply flow path 72 is connected to the inside of the second insertion hole 27. Therefore, the second supply flow path 72 connects the first supply flow path 71 and the inside of the second insertion hole 27.

[0078] The second supply flow path 72 includes a second piping portion 72a and a second hole portion 72b. The second piping portion 72a is arranged outside the housing 11. The second hole portion 72b is formed in the second plate 16. The first end of the second piping portion 72a is connected to the middle of the first piping portion 71a. The inside of the second piping portion 72a is connected to the inside of the first piping portion 71a. The second end of the second piping portion 72a is connected to the first end of the second hole portion 72b. The second piping portion 72a is connected to the second hole portion 72b. The second end of the second hole portion 72b is connected to the inside of the second insertion hole 27. The second hole portion 72b is connected to the inside of the second insertion hole 27. Specifically, the second end of the second hole portion 72b is connected to a portion of the inside of the second insertion hole 27 that is closer to the motor chamber 19 than the second sealing member 45.

[0079] A part of the air flowing in the second suction pipe 40 flows into the first pipe portion 71a of the first supply flow path 71. The air passing through the first pipe portion 71a flows into the thrust bearing accommodation chamber 25 via the first hole portion 71b. The air flowing into the thrust bearing accommodation chamber 25 cools the thrust bearing 55. The air after cooling the thrust bearing 55 passes through the inside of the first bearing holding portion 21. The air passing through the inside of the first bearing holding portion 21 cools the first radial bearing 53. Furthermore, the air after cooling the first radial bearing 53 flows into the motor chamber 19. The air flowing into the motor chamber 19 cools the motor 20.

[0080] A part of the air passing through the first piping portion 71a flows into the second piping portion 72a of the second supply flow path 72. The air passing through the second piping portion 72a flows into the inside of the second insertion hole 27 via the second hole portion 72b. The air flowing into the inside of the second insertion hole 27 passes through the inside of the second bearing holding portion 26. The air passing through the inside of the second bearing holding portion 26 cools the second radial bearing 54. Then, the air after cooling the second radial bearing 54 flows into the motor chamber 19. The air flowing into the motor chamber 19 cools the motor 20.

[0081] In this way, air for cooling the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55 flows through the air supply flow path 70. The air supply flow path 70 supplies a part of the air compressed by the first impeller 46 to the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55.

[0082] <Intercooler 73>

[0083] The centrifugal compressor 10 includes an intercooler 73. The intercooler 73 is mounted on, for example, the outer peripheral surface of the motor housing 12. A portion of the first piping portion 71a of the first supply flow path 71 passes through the interior of the intercooler 73. The portion of the first piping portion 71a that passes through the interior of the intercooler 73 is a portion that is closer to the second suction pipe 40 than the connection portion with the second piping portion 72a of the second supply flow path 72.

[0084] In addition, the interior of the intercooler 73 is communicated with the cooling water outlet 65. The cooling water discharged from the cooling water outlet 65 flows inside the intercooler 73. In the intercooler 73, heat exchange is performed between the cooling water flowing from the cooling water outlet 65 to the inside of the intercooler 73 and the air flowing through the part of the first piping portion 71a passing through the inside of the intercooler 73. Thus, the air flowing through the first piping portion 71a is cooled by the cooling water.

[0085] In this way, the intercooler 73 cools the air flowing through the air supply flow path 70. The air flowing through the air supply flow path 70 is cooled by the intercooler 73 and then supplied to the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55. The cooling water that has passed through the intercooler 73 is refluxed to the cooling water inlet 64 after the cooling water is radiated by a radiator (not shown).

[0086] <Cooling water extension flow path 66>

[0087] like Figure 2 As shown, the cooling water flow path 60 has a cooling water extension flow path 66. The cooling water extension flow path 66 extends around the first insertion hole 24. The fourth plate 18 has a first recess 67. The first recess 67 is formed on the end surface 18b of the fourth plate 18 on the first plate 15 side. The first recess 67 extends around the first insertion hole 24.

[0088] like Figure 3 As shown in FIG. 1 , the first recess 67 is formed on the end surface 18b of the fourth plate 18 so as to extend 270 degrees around the first insertion hole 24. Figure 2 As shown, the opening of the first recess 67 is closed by the end surface 17a of the third plate 17. The third plate 17 and the fourth plate 18 are sealed by a sealing member 68. Furthermore, the cooling water extension flow path 66 is demarcated by the first recess 67 and the third plate 17. Therefore, the fourth plate 18 is a first shell structure having a first recess 67 that forms the cooling water extension flow path 66 and extends around the first insertion hole 24. Therefore, the first partition wall has a first shell structure. In this way, the cooling water extension flow path 66 is formed in the first partition wall and extends around the first insertion hole 24. As shown in FIG. Figure 3 As shown, the cooling water extension flow path 66 extends around the first insertion hole 24 over 270 degrees.

[0089] like Figure 2As shown, the fourth plate 18 has a first connecting flow path 69a and a second connecting flow path 69b. The first end of the first connecting flow path 69a is connected to the second water channel 62. The second end of the first connecting flow path 69a is connected to the first end of the cooling water extension flow path 66. The first end of the second connecting flow path 69b is connected to the cooling water extension flow path 66. The connection portion at the first end of the second connecting flow path 69b connected to the cooling water extension flow path 66 is a portion 180 degrees away from the first end of the cooling water extension flow path 66, for example, around the first insertion hole 24. The second end of the second connecting flow path 69b is connected to the second water channel 62. And a part of the cooling water flowing in the second water channel 62 flows into the first end of the cooling water extension flow path 66 via the first connecting flow path 69a. The cooling water extension flow path 66 is filled with the cooling water flowing from the second water channel 62. Then, the cooling water flowing through the cooling water extension flow path 66 flows back to the second water path 62 via the second connecting flow path 69 b .

[0090] <Air Return Flow Path 74 and Air Extension Flow Path 75>

[0091] The centrifugal compressor 10 includes an air return flow path 74. The air return flow path 74 includes an air extension flow path 75. The third plate 17 includes a mounting recess 76. The mounting recess 76 is formed on an end surface on the bottom surface side of the fitting recess 22 in the third plate 17. The third plate 17 includes a second recess 77. The second recess 77 is formed on the bottom surface of the mounting recess 76.

[0092] like Figure 3 As shown in FIG. 1 , the mounting recess 76 and the second recess 77 extend along the first recess 67. The mounting recess 76 and the second recess 77 are formed on the third plate 17 so as to overlap with the first recess 67 in the thickness direction of the third plate 17 and extend over 270 degrees around the first insertion hole 24. The second recess 77 extends around the first insertion hole 24. A sealing assembly groove 78 is formed on the bottom surface of the mounting recess 76. The sealing assembly groove 78 is formed on the bottom surface of the mounting recess 76 so as to surround the second recess 77.

[0093] like Figure 2 As shown, the third plate 17 has a protruding wall 79. The protruding wall 79 protrudes from the end surface 17a of the third plate 17. The protruding wall 79 extends along the second recess 77. A portion of the second recess 77 is formed inside the protruding wall 79. The protruding wall 79 protrudes from the end surface 17a of the third plate 17 by an amount corresponding to the formation of the second recess 77. The protruding wall 79 enters the inner side of the first recess 67.

[0094] The centrifugal compressor 10 includes a cover member 80. The cover member 80 closes the opening of the second recess 77. The cover member 80 is a part of the first partition wall that separates the first impeller chamber 29 from the motor chamber 19. Therefore, the partition wall has the cover member 80. The cover member 80 closes the opening of the second recess 77 and defines the air extension flow path 75 together with the second recess 77. Therefore, the air extension flow path 75 extends along the cooling water extension flow path 66. The air extension flow path 75 extends along the cooling water extension flow path 66 inside the first partition wall. The air extension flow path 75 extends around the first insertion hole 24. As shown in FIG. Figure 3 As shown, the air extension flow path 75 extends around the first insertion hole 24 over 270 degrees.

[0095] like Figure 2 As shown, a sealing member 81 is mounted in the sealing assembly groove 78. The sealing member 81 seals between the cover member 80 and the third plate 17. The first plate 15 has a first introduction hole 82. The cover member 80 has a second introduction hole 83. The first end of the first introduction hole 82 communicates with the inside of the motor chamber 19. The second end of the first introduction hole 82 communicates with the first end of the second introduction hole 83. The second end of the second introduction hole 83 communicates with the first end of the air extension flow path 75.

[0096] The air return flow path 74 has a return flow path 84. The return flow path 84 penetrates the third plate 17, the fourth plate 18, and the first compressor housing 13 and is connected to the first suction pipe 32. The air in the motor chamber 19 returns to the first suction pipe 32 via the first introduction hole 82, the second introduction hole 83, the air extension flow path 75, and the return flow path 84. Therefore, the first introduction hole 82, the second introduction hole 83, the air extension flow path 75, and the return flow path 84 constitute the air return flow path 74 that returns the air after cooling the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55 to the first suction passage 33.

[0097] The air extension flow path 75 is a portion of the air return flow path 74 that extends along the cooling water extension flow path 66 . Therefore, a portion of the air return flow path 74 extends along the cooling water flow path 60 .

[0098] <Next Door 85>

[0099] The portion of the third plate 17 that closes the opening of the first recess 67 and the protruding wall 79 are the partition wall 85 that extends along the cooling water extension flow path 66 and separates the air extension flow path 75 from the cooling water extension flow path 66. Furthermore, the opening of the first recess 67 is closed by the partition wall 85. The partition wall 85 and the first recess 67 define the cooling water extension flow path 66. Therefore, the third plate 17 is a second housing structure that forms the air extension flow path 75, has the second recess 77, has the partition wall 85, and closes the opening of the first recess 67 and defines the cooling water extension flow path 66 together with the first recess 67.

[0100] The partition wall 85 performs heat exchange between the air flowing in the air extension flow path 75 and the cooling water flowing in the cooling water extension flow path 66. In this way, the centrifugal compressor 10 includes the partition wall 85 that extends along the cooling water flow path 60, separates the air return flow path 74 from the cooling water flow path 60, and performs heat exchange between the air flowing in the air return flow path 74 and the cooling water flowing in the cooling water flow path 60. The air flowing in the air extension flow path 75 dissipates heat to the cooling water flowing in the cooling water extension flow path 66 via the partition wall 85. Therefore, the air flowing in the air return flow path 74 dissipates heat to the cooling water flowing in the cooling water flow path 60 via the partition wall 85.

[0101] [Function of the first embodiment]

[0102] Next, the operation of this embodiment will be described.

[0103] In the following description, “the air after cooling the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55” may be simply described as “the air after cooling the motor 20, the first radial bearing 53, etc.” Also, “the air supplied from the air supply passage 70 to the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55” may be simply described as “the air supplied from the air supply passage 70 to the motor 20, the first radial bearing 53, etc.”

[0104] The air after cooling the motor 20 and the first radial bearing 53, etc., flows back to the first suction passage 33 via the air return flow path 74. The pressure of the air flowing in the first suction passage 33 is the pressure of the air sucked into the first impeller chamber 29, that is, the suction pressure. The suction pressure is stable because it is easy to be uniquely determined according to the specifications of the centrifugal compressor 10. Therefore, the pressure of the air compressed and discharged by the first impeller 46, that is, the difference between the discharge pressure and the suction pressure is difficult to change. Therefore, the flow rate of the air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53, etc. is difficult to change. Therefore, the flow rate of the air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53, etc. is stable.

[0105] When the air after cooling the motor 20 and the first radial bearing 53 and the like is refluxed to the first intake passage 33 through the air reflux passage 74, heat exchange is performed between the air flowing in the air reflux passage 74 and the cooling water flowing in the cooling water passage 60 through the partition 85. Here, the partition 85 extends along the cooling water passage 60. Therefore, the air flowing in the air reflux passage 74 efficiently dissipates heat to the cooling water flowing in the cooling water passage 60 through the partition 85. Thus, the air flowing in the air reflux passage 74 is efficiently cooled by the cooling water flowing in the cooling water passage 60. Furthermore, the air cooled by the cooling water is refluxed to the first intake passage 33 through the air reflux passage 74. Therefore, even if the air after cooling the motor 20 and the first radial bearing 53 and the like is refluxed to the first intake passage 33 through the air reflux passage 74, the temperature of the air sucked from the first intake passage 33 to the first impeller chamber 29 can be prevented from increasing. Therefore, even if the air that has cooled the motor 20 and the first radial bearing 53 is returned to the first intake passage 33 via the air return flow path 74 , high-temperature air can be prevented from being compressed by the first impeller 46 , thereby preventing compression efficiency from being deteriorated.

[0106] [Effects of the First Embodiment]

[0107] The following effects can be obtained in the above-mentioned embodiment.

[0108] (1-1) The air after cooling the motor 20 and the first radial bearing 53, etc., flows back to the first intake passage 33 via the air return flow path 74. As a result, the flow rate of the air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53, etc. is less likely to change. Therefore, the flow rate of the air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53, etc. can be stabilized. As a result, the motor 20 and the first radial bearing 53 can be stably cooled by air.

[0109] When the air after cooling the motor 20 and the first radial bearing 53 and the like is refluxed to the first intake passage 33 through the air reflux passage 74, heat exchange is performed between the air flowing in the air reflux passage 74 and the cooling water flowing in the cooling water passage 60 through the partition 85. Here, the partition 85 extends along the cooling water passage 60. Therefore, the air flowing in the air reflux passage 74 efficiently dissipates heat to the cooling water flowing in the cooling water passage 60 through the partition 85. Thus, the air flowing in the air reflux passage 74 can be efficiently cooled by the cooling water flowing in the cooling water passage 60. Furthermore, the air cooled by the cooling water is refluxed to the first intake passage 33 through the air reflux passage 74. Therefore, even if the air after cooling the motor 20 and the first radial bearing 53 and the like is refluxed to the first intake passage 33 through the air reflux passage 74, the temperature of the air sucked from the first intake passage 33 to the first impeller chamber 29 can be prevented from increasing. Therefore, even if the air after cooling the motor 20 and the first radial bearing 53 is refluxed to the first intake passage 33 via the air reflux passage 74, it is possible to avoid compressing the high-temperature air by the first impeller 46, thereby avoiding deterioration of the compression efficiency. Through the above, the motor 20 and the first radial bearing 53 can be stably cooled by air while avoiding deterioration of the compression efficiency.

[0110] (1-2) The third plate 17 and the fourth plate 18 are portions relatively close to the first intake passage 33 in the housing 11. Furthermore, the air extension passage 75 extends along the cooling water extension passage 66 formed by the third plate 17 and the fourth plate 18. The air flowing in the air extension passage 75 dissipates heat to the cooling water flowing in the cooling water extension passage 66 via the partition 85. Therefore, the air flowing in the air return passage 74 can dissipate heat to the cooling water flowing in the cooling water passage 60 via the partition 85 at a portion relatively close to the first intake passage 33 in the housing 11. Furthermore, the air can then be returned to the first intake passage 33 via the air return passage 74. Therefore, the air can be returned to the first intake passage 33 while minimizing the possibility that the air cooled by the cooling water flowing in the cooling water passage 60 is heated again. As a result, even if the air after cooling the motor 20 and the first radial bearing 53 is refluxed to the first suction passage 33 via the air reflux passage 74, it is easy to avoid the temperature of the air sucked from the first suction passage 33 to the first impeller chamber 29 from increasing. Therefore, even if the air after cooling the motor 20 and the first radial bearing 53 is refluxed to the first suction passage 33 via the air reflux passage 74, it is easy to avoid the high-temperature air being compressed by the first impeller 46. Therefore, it is easy to avoid the compression efficiency from being deteriorated.

[0111] (1-3) By closing the opening of the first recess 67 with the partition wall 85, the cooling water extension flow path 66 extending around the first insertion hole 24 can be formed. Furthermore, by closing the opening of the second recess 77 with the cover member 80, the air extension flow path 75 extending along the cooling water extension flow path 66 can be formed. Furthermore, it can be configured so that the air flowing through the air extension flow path 75 can dissipate heat to the cooling water flowing through the cooling water extension flow path 66 via the partition wall 85.

[0112] (1-4) The heat of the air compressed by the first impeller 46 is easily transferred to the third plate 17 and the fourth plate 18. In addition, the heat of the air compressed by the second impeller 47 is easily transferred to the second plate 16. The second impeller 47 compresses the air compressed by the first impeller 46, so the temperature of the air compressed by the second impeller 47 is higher than the temperature of the air compressed by the first impeller 46. Therefore, the temperature of the second plate 16 is higher than the temperature of the third plate 17 and the fourth plate 18. Therefore, the cooling water extension flow path 66 is formed by the third plate 17 and the fourth plate 18. Therefore, for example, compared with the case where the cooling water extension flow path 66 is formed in the second plate 16, the temperature of the cooling water flowing in the cooling water extension flow path 66 can be maintained at a low state. In addition, the air flowing in the air extension flow path 75 dissipates heat to the cooling water flowing in the cooling water extension flow path 66 via the partition wall 85. Since the temperature of the cooling water flowing in the cooling water extension flow path 66 is maintained at a low state, the air flowing in the air extension flow path 75 can efficiently dissipate heat to the cooling water flowing in the cooling water extension flow path 66 via the partition wall 85 .

[0113] Furthermore, the air return flow path 74 returns the air after cooling the motor 20 and the first radial bearing 53, etc., to the first intake passage 33. The pressure of the air flowing in the first intake passage 33 is lower than the pressure of the air flowing in the second intake passage 41. Therefore, for example, compared with the case where the air return flow path 74 returns the air after cooling the motor 20 and the first radial bearing 53, etc. to the second intake passage 41, the pressure of the air at the return destination of the air is as low as possible, so it is easy to generate a difference between the discharge pressure and the pressure of the return destination of the air. Therefore, it is easy to ensure the flow rate of air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53, etc., so that the motor 20 and the second radial bearing 54, etc. can be stably cooled by air.

[0114] (1-5) The air flowing through the air supply passage 70 can be cooled by the intercooler 73. Therefore, a part of the air compressed by the first impeller 46 can be supplied from the air supply passage 70 to the motor 20 and the first radial bearing 53 in a state of reduced temperature. Therefore, the motor 20 and the first radial bearing 53 can be efficiently cooled by the air from the air supply passage 70.

[0115] (1-6) For example, if the air is discharged to the atmosphere, exhaust sound of the air may be generated when the air is discharged to the atmosphere. However, in the present embodiment, since the air is not discharged to the atmosphere but is returned to the first intake pipe 32, exhaust sound of the air is not generated. Therefore, noise reduction can be achieved.

[0116] (1-7) For example, if the air is discharged to the atmosphere, water may enter from the outside. However, in the present embodiment, since the air is not discharged to the atmosphere but is returned to the first suction pipe 32, water can be prevented from entering from the outside.

[0117] (1-8) For example, if the air is discharged to the atmosphere, the pressure loss caused by the length and diameter of the pipe is different for each fuel cell system including the centrifugal compressor 10. Therefore, the discharge pressure discharged to the atmosphere is also different for each system including the centrifugal compressor 10. Therefore, if the centrifugal compressor 10 is mounted on different fuel cell systems, the difference between the pressure of the air compressed and discharged by the first impeller 46, that is, the discharge pressure and the discharge pressure discharged to the atmosphere is different for each fuel cell system. If the difference between the discharge pressure and the discharge pressure is different, the flow rate of air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53 is also different. Therefore, it is possible that the flow rate of air supplied to the motor 20 and the first radial bearing 53 is adjusted independently for each fuel cell system. However, in the present embodiment, the flow rate of air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53 is stabilized only by refluxing the air to the first intake passage 33. Therefore, there is no need to change the configuration of the fuel cell system side, the configuration of the air supply flow path 70 , etc. in order to stabilize the flow rate of air supplied from the air supply flow path 70 to the motor 20 and the first radial bearing 53 .

[0118] (1-9) Since the air is refluxed to the first intake passage 33 , the amount of air supplied to the fuel cell stack 39 can be easily estimated by understanding the flow rate of air sucked from the first intake passage 33 into the first impeller chamber 29 .

[0119] (1-10) Even if the air after cooling the motor 20 and the first radial bearing 53 is refluxed to the first intake passage 33 via the air reflux passage 74, it is possible to prevent the temperature of the air sucked from the first intake passage 33 to the first impeller chamber 29 from increasing. Therefore, it is possible to suppress the situation where the density of oxygen contained in the air decreases and the oxygen contained in the air supplied to the fuel cell stack 39 decreases. Therefore, it is possible to suppress the decrease in the power generation efficiency in the fuel cell stack 39.

[0120] [Second embodiment]

[0121] Below, according to Figure 4 as well as Figure 5 A second embodiment of a centrifugal compressor is described. In addition, in the embodiments described below, the same components as those in the first embodiment described above are marked with the same reference numerals, and the repeated descriptions are omitted or simplified. In the second embodiment, the configuration of the cooling water extension flow path and the air return flow path is different from that in the first embodiment.

[0122] <Cooling water extension flow path 90>

[0123] like Figure 4 As shown, the fourth plate 18 has a recess 91. The recess 91 is formed on the end surface 18b of the fourth plate 18. The recess 91 is formed on the end surface 18b of the fourth plate 18 so as to extend 270 degrees around the first insertion hole 24. The recess 91 extends around the first insertion hole 24. The opening of the recess 91 is closed by the first plate 15. The first plate 15 and the fourth plate 18 are sealed by a sealing member 92. In addition, a cooling water extension flow path 90 is defined by the recess 91 and the first plate 15. The cooling water extension flow path 90 extends 270 degrees around the first insertion hole 24.

[0124] Therefore, the fourth plate 18 is a first housing component having a recessed portion 91 that forms the cooling water extension flow path 90 and extends around the first insertion hole 24. The first plate 15 is a second housing component that closes the opening of the recessed portion 91 and defines the cooling water extension flow path 90 together with the recessed portion 91. The first partition wall has a first housing component and a second housing component. In this way, the cooling water extension flow path 90 is formed in the first partition wall and extends around the first insertion hole 24.

[0125] The first end of the cooling water extension flow path 90 is connected to the first connection flow path 69a. The cooling water extension flow path 90 is connected to the second connection flow path 69b at a portion 180 degrees away from the first insertion hole 24 relative to the first end. In addition, a portion of the cooling water flowing in the second water path 62 flows into the first end of the cooling water extension flow path 90 via the first connection flow path 69a. The cooling water extension flow path 90 is filled with the cooling water flowing in from the second water path 62. In addition, the cooling water flowing in the cooling water extension flow path 90 flows back to the second water path 62 via the second connection flow path 69b.

[0126] <Air Return Flow Path 93 and Air Extension Flow Path 94>

[0127] A through hole 95 is formed in the first plate 15 . The through hole 95 penetrates the first plate 15 in the thickness direction. A first end of the through hole 95 communicates with the inside of the motor chamber 19 . A second end of the through hole 95 communicates with the cooling water extension flow path 90 .

[0128] like Figure 4 as well as Figure 5 As shown, the centrifugal compressor 10 includes a pipe member 96 constituting an air extension flow path 94. The pipe member 96 includes an extension portion 96a, an introduction portion 96b, and a discharge portion 96c. The extension portion 96a passes through the inner side of the cooling water extension flow path 90. The extension portion 96a extends along the cooling water extension flow path 90. The extension portion 96a is arranged on the inner side of the cooling water extension flow path 90 so as to extend 270 degrees around the first insertion hole 24. The extension portion 96a passes through the inner side of the cooling water extension flow path 90 to constitute the air extension flow path 94. Therefore, the pipe member 96 passes through the inner side of the cooling water extension flow path 90 to constitute the air extension flow path 94. The air extension flow path 94 extends 270 degrees around the first insertion hole 24.

[0129] The introduction portion 96b is a cylindrical shape extending straightly. The introduction portion 96b is connected to the first end of the extension portion 96a. The introduction portion 96b is inserted into the through hole 95. A sealing member 97 is provided between the introduction portion 96b and the through hole 95. The sealing member 97 seals between the introduction portion 96b and the through hole 95. The introduction portion 96b is connected to the motor chamber 19. The introduction portion 96b connects the motor chamber 19 to the air extension flow path 94.

[0130] The discharge portion 96c is a cylindrical shape extending straightly. The discharge portion 96c is connected to the second end of the extension portion 96a. Figure 4 As shown, the air return flow path 93 has a return flow path 98. The return flow path 98 penetrates the fourth plate 18 and the first compressor housing 13 and is connected to the first suction pipe 32. The first end of the return flow path 98 communicates with the discharge portion 96c. The second end of the return flow path 98 communicates with the first suction pipe 32.

[0131] The air in the motor chamber 19 flows back into the first suction pipe 32 via the inside of the introduction portion 96b, the air extension flow path 94, the inside of the discharge portion 96c, and the return flow path 98. The inside of the introduction portion 96b, the air extension flow path 94, the inside of the discharge portion 96c, and the return flow path 98 constitute an air return flow path 93 for returning the air after cooling the motor 20, the first radial bearing 53, the second radial bearing 54, and the thrust bearing 55 to the first suction passage 33.

[0132] The air extension flow path 94 is a portion of the air return flow path 93 that extends along the cooling water extension flow path 90 . Therefore, a portion of the air return flow path 93 extends along the cooling water flow path 60 .

[0133] <Next Door 99>

[0134] The wall of the extension portion 96a is a partition wall 99 extending along the cooling water extension flow path 90 and partitioning the air extension flow path 94 from the cooling water extension flow path 90. Therefore, the wall of the portion of the pipe member 96 passing through the inside of the cooling water extension flow path 90 constitutes the partition wall 99.

[0135] The partition wall 99 performs heat exchange between the air flowing in the air extension flow path 94 and the cooling water flowing in the cooling water extension flow path 90. In this way, the centrifugal compressor 10 includes the partition wall 99 that extends along the cooling water flow path 60, separates the air return flow path 93 from the cooling water flow path 60, and performs heat exchange between the air flowing in the air return flow path 93 and the cooling water flowing in the cooling water flow path 60. The air flowing in the air extension flow path 94 dissipates heat to the cooling water flowing in the cooling water extension flow path 90 via the partition wall 99. Therefore, the air flowing in the air return flow path 93 dissipates heat to the cooling water flowing in the cooling water flow path 60 via the partition wall 99.

[0136] [Effects of the Second Embodiment]

[0137] In the second embodiment, in addition to all the effects except the effect (1-3) of the first embodiment, the following effects can be obtained.

[0138] (2-1) By closing the opening of the recess 91 with the first plate 15, the cooling water extension flow path 90 extending around the first insertion hole 24 can be formed. Furthermore, by passing the pipe member 96 inside the cooling water extension flow path 90, the air extension flow path 94 extending along the cooling water extension flow path 90 can be formed by the pipe member 96. In addition, the wall portion of the portion of the pipe member 96 passing through the inside of the cooling water extension flow path 90 constitutes the partition wall 99. Thus, it can be configured so that the air flowing through the air extension flow path 94 can dissipate heat to the cooling water flowing through the cooling water extension flow path 90 via the partition wall 99.

[0139] [Change example]

[0140] In addition, the above-mentioned embodiments can be implemented by changing as follows. The above-mentioned embodiments and the following modified examples can be implemented in combination with each other within the range of no technical contradiction.

[0141] In the first embodiment, the cooling water extension flow path 66 may be formed in the second plate 16 so as to extend around the second insertion hole 27 . Furthermore, the air extension flow path 75 may extend along the cooling water extension flow path 66 inside the second plate 16 .

[0142] In the first embodiment, the position of the air return flow path 74 relative to the housing 11 is not particularly limited as long as it extends along the cooling water flow path 60. In short, the air return flow path 74 allows the air after cooling the motor 20 and the first radial bearing 53 to return to the first intake passage 33 or the second intake passage 41 and extend along the cooling water flow path 60. In addition, the following structure is sufficient: the partition wall 85 separating the air return flow path 74 from the cooling water flow path 60 extends along the cooling water flow path 60, and the air flowing in the air return flow path 74 dissipates heat to the cooling water flowing in the cooling water flow path 60 via the partition wall 85.

[0143] In the second embodiment, the cooling water extension flow path 90 may be formed in the second plate 16 so as to extend around the second insertion hole 27. Furthermore, the centrifugal compressor 10 may include a pipe member 96 that passes through the inside of the cooling water extension flow path 90 and constitutes the air extension flow path 94.

[0144] In the first embodiment, the first recess 67 may not extend 270 degrees around the first insertion hole 24. Therefore, the cooling water extension flow path 66 may not extend 270 degrees around the first insertion hole 24. Furthermore, the air extension flow path 75 may not extend 270 degrees around the first insertion hole 24. In short, the air extension flow path 75 may extend along the cooling water extension flow path 66.

[0145] In the second embodiment, the recessed portion 91 may not extend 270 degrees around the first insertion hole 24. Therefore, the cooling water extension flow path 90 may not extend 270 degrees around the first insertion hole 24. Furthermore, the air extension flow path 94 may not extend 270 degrees around the first insertion hole 24. In short, the air extension flow path 94 may extend along the cooling water extension flow path 90.

[0146] In the above-mentioned embodiments, the arrangement position of the intercooler 73 with respect to the housing 11 is not particularly limited.

[0147] In the above-described embodiments, as long as the temperature of the air compressed by the first impeller 46 is a temperature capable of cooling the motor 20 and the first radial bearing 53 , etc., the centrifugal compressor 10 may be configured without the intercooler 73 .

[0148] In each of the above-mentioned embodiments, the air supply passage 70 may supply a portion of the air compressed by the second impeller 47 to the motor 20 and the first radial bearing 53, etc. Furthermore, the air return passages 74 and 93 may return the air after cooling the motor 20 and the first radial bearing 53, etc., to the second intake passage 41.

[0149] In each of the above-described embodiments, the centrifugal compressor 10 may be configured not to include the second impeller 47 .

[0150] In each of the above-described embodiments, the centrifugal compressor 10 may be configured to include a turbine impeller instead of the second impeller 47 .

[0151] In each of the above-mentioned embodiments, the centrifugal compressor 10 may not be mounted on the fuel cell vehicle. In short, the centrifugal compressor 10 is not limited to being mounted on a vehicle.

[0152] The above-mentioned embodiment includes the configurations described in the following supplementary notes.

[0153] <Additional Note 1>

[0154] A centrifugal compressor comprising:

[0155] Axis of rotation;

[0156] a bearing for rotatably supporting the rotating shaft;

[0157] a motor to rotate the rotating shaft;

[0158] an impeller that compresses air by rotating integrally with the rotating shaft;

[0159] a housing having an impeller chamber for accommodating the impeller and a motor chamber for accommodating the motor;

[0160] a suction passage for sucking air into the impeller chamber;

[0161] a cooling water flow path for cooling water for cooling the motor and the bearing; and

[0162] an air supply passage for supplying a part of the air compressed by the impeller to the motor and the bearing to cool the motor and the bearing,

[0163] It is characterized in that

[0164] The centrifugal compressor comprises:

[0165] an air return flow path extending along the cooling water flow path and causing the air after cooling the motor and the bearing to return to the intake passage; and

[0166] a partition wall extending along the cooling water flow path and separating the air return flow path from the cooling water flow path and performing heat exchange between the air flowing in the air return flow path and the cooling water flowing in the cooling water flow path,

[0167] The air flowing through the air recirculation flow path transfers heat to the cooling water flowing through the cooling water flow path via the partition wall.

[0168] <Note 2>

[0169] The centrifugal compressor according to <Supplementary Note 1> is characterized in that:

[0170] The housing has a partition wall that partitions the impeller chamber from the motor chamber and is formed with an insertion hole through which the rotating shaft is inserted.

[0171] The cooling water flow path includes a cooling water extension flow path formed in the partition wall and extending around the insertion hole.

[0172] The air return flow path includes an air extension flow path extending along the cooling water extension flow path inside the partition wall.

[0173] The partition wall extends along the cooling water extension flow path and separates the air extension flow path from the cooling water extension flow path, and performs heat exchange between the air flowing in the air extension flow path and the cooling water flowing in the cooling water extension flow path.

[0174] The air flowing through the air extension flow path transfers heat to the cooling water flowing through the cooling water extension flow path via the partition wall.

[0175] <Addendum 3>

[0176] The centrifugal compressor according to <Supplementary Note 2> is characterized in that:

[0177] The partition wall has:

[0178] a first housing component having a first recessed portion which forms the cooling water extension flow path and extends around the insertion hole;

[0179] a second housing structure having a second recessed portion that forms the air extension flow path and extends around the insertion hole and having the partition wall, the partition wall being used to close the opening of the first recessed portion and to define the cooling water extension flow path together with the first recessed portion; and

[0180] The cover member closes the opening of the second recess and defines the air extension flow path together with the second recess.

[0181] <Addendum 4>

[0182] The centrifugal compressor according to <Supplementary Note 2> is characterized in that:

[0183] The partition wall has:

[0184] a first housing component having a recessed portion that forms the cooling water extension flow path and extends around the insertion hole; and

[0185] The second housing structure seals the opening of the recess and defines the cooling water extension flow path together with the recess.

[0186] The centrifugal compressor includes a pipe member passing through the inner side of the cooling water extension flow path and constituting the air extension flow path.

[0187] The wall portion of the portion of the pipe member that passes through the inner side of the cooling water extension flow path constitutes the partition wall.

[0188] <Addendum 5>

[0189] The centrifugal compressor according to any one of <Supplement 2> to <Supplement 4>, characterized in that

[0190] The impeller comprises:

[0191] The first impeller compresses the air; and

[0192] The second impeller compresses the air compressed by the first impeller.

[0193] The impeller chamber comprises:

[0194] a first impeller chamber for accommodating the first impeller; and

[0195] a second impeller chamber for accommodating the second impeller,

[0196] The inhalation pathway comprises:

[0197] a first suction passage for sucking air into the first impeller chamber; and

[0198] a second suction passage for sucking air into the second impeller chamber,

[0199] The partition wall comprises:

[0200] a first partition wall that separates the first impeller chamber from the motor chamber; and

[0201] a second partition wall, separating the second impeller chamber from the motor chamber,

[0202] The insertion hole comprises:

[0203] a first insertion hole formed in the first partition wall and through which the rotating shaft is inserted; and

[0204] a second insertion hole formed in the second partition wall and through which the rotating shaft is inserted,

[0205] The cooling water extension flow path is formed in the first partition wall and extends around the first insertion hole.

[0206] The air extension channel extends along the cooling water extension channel inside the first partition wall.

[0207] The air return flow path returns the air that has cooled the motor and the bearing to the first intake passage.

[0208] <Addendum 6>

[0209] The centrifugal compressor according to any one of <Supplement 1> to <Supplement 5>, characterized in that:

[0210] The centrifugal compressor includes an intercooler for cooling air flowing through the air supply flow path.

[0211] The air flowing through the air supply flow path is cooled by the intercooler and then supplied to the motor and the bearing.

[0212] Description of Reference Numerals

[0213] 10 Centrifugal compressor

[0214] 11 Shell

[0215] 15 First plate (first partition wall as a partition wall, second shell component of the second embodiment)

[0216] 16 The second plate (the second partition wall as a partition wall)

[0217] 17 Third plate (first partition wall as a partition wall, second shell component of the first embodiment)

[0218] 18 Fourth plate (first partition wall as partition wall, first shell component)

[0219] 19 Motor room

[0220] 20 motors

[0221] 24 1st insertion hole (insertion hole)

[0222] 27 2nd insertion hole (insertion hole)

[0223] 291st impeller chamber (impeller chamber)

[0224] 331st inhalation passage (inhalation passage)

[0225] 35 2nd impeller chamber (impeller chamber)

[0226] 41 Second suction passage (suction passage)

[0227] 42 Rotation axis

[0228] 461st impeller (impeller)

[0229] 47 2nd impeller (impeller)

[0230] 53 No. 1 radial bearing (bearing)

[0231] 54 No. 2 radial bearing (bearing)

[0232] 55 thrust bearing (bearing)

[0233] 60 cooling water path

[0234] 66, 90 cooling water extension flow path

[0235] 67 1st recess

[0236] 70 Air supply flow path

[0237] 73 intercooler

[0238] 74, 93 air return flow path

[0239] 75, 94 air extension flow path

[0240] 77 2nd recess

[0241] 80 Cover member

[0242] 85, 99 next door

[0243] 91 concavity

[0244] 96 pipe components

Claims

1. A centrifugal compressor comprising: Axis of rotation; a bearing for rotatably supporting the rotating shaft; a motor to rotate the rotating shaft; an impeller that compresses air by rotating integrally with the rotating shaft; a housing having an impeller chamber for accommodating the impeller and a motor chamber for accommodating the motor; a suction passage for sucking air into the impeller chamber; A cooling water flow path for cooling the motor and the bearing; as well as an air supply passage for supplying a part of the air compressed by the impeller to the motor and the bearing to cool the motor and the bearing, It is characterized in that The centrifugal compressor comprises: an air return flow path extending along the cooling water flow path and causing the air after cooling the motor and the bearing to return to the intake passage; and a partition wall extending along the cooling water flow path and separating the air return flow path from the cooling water flow path and performing heat exchange between the air flowing in the air return flow path and the cooling water flowing in the cooling water flow path, The air flowing through the air recirculation flow path transfers heat to the cooling water flowing through the cooling water flow path via the partition wall.

2. The centrifugal compressor according to claim 1, characterized in that: The housing has a partition wall that partitions the impeller chamber from the motor chamber and is formed with an insertion hole through which the rotating shaft is inserted. The cooling water flow path includes a cooling water extension flow path formed in the partition wall and extending around the insertion hole. The air return flow path includes an air extension flow path extending along the cooling water extension flow path inside the partition wall. The partition wall extends along the cooling water extension flow path and separates the air extension flow path from the cooling water extension flow path, and performs heat exchange between the air flowing in the air extension flow path and the cooling water flowing in the cooling water extension flow path. The air flowing through the air extension flow path transfers heat to the cooling water flowing through the cooling water extension flow path via the partition wall.

3. The centrifugal compressor according to claim 2, characterized in that: The partition wall has: a first housing component having a first recessed portion which forms the cooling water extension flow path and extends around the insertion hole; a second housing structure having a second recessed portion that forms the air extension flow path and extends around the insertion hole and having the partition wall, the partition wall being used to close the opening of the first recessed portion and to define the cooling water extension flow path together with the first recessed portion; as well as The cover member closes the opening of the second recess and defines the air extension flow path together with the second recess.

4. The centrifugal compressor according to claim 2, characterized in that: The partition wall has: a first housing component having a recessed portion that forms the cooling water extension flow path and extends around the insertion hole; and The second housing structure seals the opening of the recess and defines the cooling water extension flow path together with the recess. The centrifugal compressor includes a pipe member passing through the inner side of the cooling water extension flow path and constituting the air extension flow path. The wall portion of the portion of the pipe member that passes through the inner side of the cooling water extension flow path constitutes the partition wall.

5. The centrifugal compressor according to any one of claims 2 to 4, characterized in that: The impeller comprises: The first impeller compresses the air; and The second impeller compresses the air compressed by the first impeller. The impeller chamber comprises: a first impeller chamber for accommodating the first impeller; and a second impeller chamber for accommodating the second impeller, The inhalation pathway comprises: a first suction passage for sucking air into the first impeller chamber; and a second suction passage for sucking air into the second impeller chamber, The partition wall comprises: a first partition wall that separates the first impeller chamber from the motor chamber; and a second partition wall, separating the second impeller chamber from the motor chamber, The insertion hole comprises: a first insertion hole formed in the first partition wall and through which the rotating shaft is inserted; and a second insertion hole formed in the second partition wall and through which the rotating shaft is inserted, The cooling water extension flow path is formed in the first partition wall and extends around the first insertion hole. The air extension channel extends along the cooling water extension channel inside the first partition wall. The air return flow path returns the air that has cooled the motor and the bearing to the first intake passage.

6. The centrifugal compressor according to claim 1, characterized in that: The centrifugal compressor includes an intercooler for cooling the air flowing through the air supply flow path. The air flowing through the air supply flow path is cooled by the intercooler and then supplied to the motor and the bearing.

Images