Centrifugal compressor

Abstract

To efficiently cool a cooling object part while preventing a decrease in operation efficiency of a centrifugal compressor.SOLUTION: An introduction passage 70 includes: a first adjustment valve 75 in which a valve opening increases as the difference pressure between an air ejection pressure and an atmospheric pressure after being compressed by a rotation of a first impeller 61 decreases to increase a passage cross sectional area of the introduction passage 70 and a valve opening decreases as the difference pressure between an air ejection pressure and an atmospheric pressure after being compressed by a rotation of the first impeller 61 increases to decrease a passage cross sectional area of the introduction passage 70; and a second adjustment valve 76 in which a valve opening increases as the temperature of a first dynamic pressure slide bearing 56 increases to increase the passage cross sectional area of the introduction passage 70 and a valve opening decreases as the temperature of the first dynamic pressure slide bearing 56 decreases to decrease the passage cross sectional area of the introduction passage 70. The first adjustment valve 75 and the second adjustment valve 76 are arranged in series with the introduction passage 70.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For example, as disclosed in Patent Document 1, a centrifugal compressor includes a rotating shaft, an impeller, and a housing. The impeller rotates integrally with the rotating shaft to compress a fluid. The housing has an impeller chamber. The impeller chamber houses the impeller.

[0003] Incidentally, in a centrifugal compressor, it is desirable to cool a cooling target disposed in a housing in order to improve the durability of the centrifugal compressor. Thus, it has been considered to introduce a part of the fluid compressed by the rotation of the impeller into the housing. Such a centrifugal compressor includes an introduction passage and a discharge passage. The introduction passage introduces a part of the fluid compressed by the rotation of the impeller into the housing in order to cool the cooling target disposed in the housing. The discharge passage discharges the fluid introduced from the introduction passage into the housing and having cooled the cooling target to the outside of the housing. In this way, the part of the fluid compressed by the rotation of the impeller is introduced into the housing through the introduction passage, whereby the cooling target is cooled by the fluid. Then, the fluid having cooled the cooling target is discharged to the outside of the housing through the discharge passage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-173590 A Summary of the Invention [Problem to be solved by the invention]

[0005] The pressure inside the housing is equal to atmospheric pressure because the housing is connected to the outside through the discharge passage. The flow rate of the fluid introduced into the housing through the introduction passage increases as the pressure difference between the atmospheric pressure and the discharge pressure of the fluid compressed by the rotation of the impeller increases.

[0006] Here, for example, when a centrifugal compressor is operated in an environment with low atmospheric pressure, the suction pressure of the fluid sucked into the impeller chamber may also decrease with the decrease in atmospheric pressure. Then, when the pressure ratio of the centrifugal compressor is constant, the discharge pressure of the fluid compressed by the rotation of the impeller also decreases. As a result, the pressure difference between the discharge pressure of the fluid compressed by the rotation of the impeller and the atmospheric pressure becomes small, so the flow rate of the fluid introduced into the housing through the introduction passage decreases. Therefore, there is a risk that it may become difficult to sufficiently cool the cooling target part by the fluid introduced into the housing through the introduction passage.

[0007] On the other hand, when the centrifugal compressor is operating, for example, under a low load condition, the temperature of the part to be cooled is low, and therefore the need to cool the part to be cooled is low. Even in such a case, a part of the fluid compressed by the rotation of the impeller may be excessively introduced into the housing through the introduction passage. This increases the unnecessary compression of the fluid in the centrifugal compressor, thereby reducing the operating efficiency of the centrifugal compressor. [Means for solving the problem]

[0008] The centrifugal compressor that solves the above problem is a centrifugal compressor including: a rotating shaft; an impeller that rotates integrally with the rotating shaft to compress a fluid; a housing having an impeller chamber that accommodates the impeller; an introduction passage that introduces into the housing a part of the fluid compressed by the rotation of the impeller to cool a cooling target disposed within the housing; and a discharge passage that discharges to the outside of the housing the fluid that has been introduced from the introduction passage into the housing and has cooled the cooling target. a first adjusting valve which increases its valve opening as the pressure difference between the discharge pressure of the fluid after cooling and atmospheric pressure decreases, thereby increasing the passage cross-sectional area of ​​the introduction passage, and which decreases its valve opening as the pressure difference increases, thereby decreasing the passage cross-sectional area; and a second adjusting valve which increases its valve opening as the temperature associated with the part to be cooled increases, thereby increasing the passage cross-sectional area, and which decreases its valve opening as the temperature decreases, thereby decreasing the passage cross-sectional area, and the first adjusting valve and the second adjusting valve are arranged in series with the introduction passage.

[0009] According to this, the first adjusting valve reduces the valve opening and reduces the passage cross-sectional area of ​​the introduction passage as the pressure difference between the discharge pressure of the fluid compressed by the rotation of the impeller and the atmospheric pressure increases. Therefore, the first adjusting valve reduces the passage cross-sectional area of ​​the introduction passage when the pressure difference between the discharge pressure of the fluid and the atmospheric pressure is large and the flow rate of the fluid introduced into the housing through the introduction passage is large. This makes it possible to prevent a portion of the fluid compressed by the rotation of the impeller from being excessively introduced into the housing through the introduction passage. As a result, it is possible to avoid a decrease in the operating efficiency of the centrifugal compressor.

[0010] Also, for example, when the centrifugal compressor is operated in an environment where the atmospheric pressure is low, the suction pressure of the fluid sucked into the impeller chamber also decreases with the decrease in the atmospheric pressure. Then, when the pressure ratio of the centrifugal compressor is constant, the discharge pressure of the fluid compressed by the rotation of the impeller also decreases. As a result, the pressure difference between the discharge pressure of the fluid compressed by the rotation of the impeller and the atmospheric pressure decreases. At this time, the first regulating valve increases the valve opening degree to increase the passage cross-sectional area of ​​the introduction passage. And, the second regulating valve increases the valve opening degree to increase the passage cross-sectional area of ​​the introduction passage as the temperature associated with the cooling target increases. According to this, when the temperature of the cooling target is high and the need for cooling the cooling target is high, even if the pressure difference between the discharge pressure of the fluid and the atmospheric pressure decreases, the flow rate of the fluid introduced into the housing through the introduction passage can be increased. Therefore, the cooling target can be sufficiently cooled by the fluid introduced into the housing through the introduction passage.

[0011] On the other hand, when the centrifugal compressor is operating, for example, in a low load state, the temperature of the cooling target is low, so the need for cooling the cooling target is low. Here, when the centrifugal compressor is operating in a low load state, the pressure ratio of the centrifugal compressor is low. Therefore, when the centrifugal compressor is operating in a low load state, the discharge pressure of the fluid compressed by the rotation of the impeller is low. For this reason, the pressure difference between the discharge pressure of the fluid compressed by the rotation of the impeller and the atmospheric pressure becomes small, so that the first regulating valve increases the valve opening and increases the passage cross-sectional area of ​​the introduction passage. At this time, the second regulating valve decreases the valve opening and decreases the passage cross-sectional area of ​​the introduction passage as the temperature associated with the cooling target becomes lower. Therefore, when the temperature of the cooling target is low and the need for cooling the cooling target is low, it is possible to avoid a part of the fluid compressed by the rotation of the impeller being excessively introduced into the housing through the introduction passage. As a result, it is possible to avoid a decrease in the operating efficiency of the centrifugal compressor. As a result, it is possible to efficiently cool the cooling target while avoiding a decrease in the operating efficiency of the centrifugal compressor.

[0012] In the centrifugal compressor, the introduction passage may have an introduction hole formed in the housing, and the first adjustment valve and the second adjustment valve may be provided in the introduction hole and thereby embedded in the housing.

[0013] According to this, since the first adjusting valve and the second adjusting valve are embedded in the housing, there is no need to prepare space for providing the first adjusting valve and the second adjusting valve around the outside of the housing. Therefore, since a part of the space around the outside of the housing is not used as the space for providing the first adjusting valve and the second adjusting valve, the space around the outside of the housing can be effectively used as the space for providing another component provided around the outside of the housing.

[0014] In the above-mentioned centrifugal compressor, the second adjustment valve has a temperature sensor, and heat from the object to be cooled can be transferred to the temperature sensor via the housing. The second adjustment valve may autonomously change its valve opening degree as a result of the temperature sensor operating in response to the transfer of heat from the object to be cooled.

[0015] This configuration is suitable as a second adjusting valve that is embedded in a housing and whose valve opening increases as the temperature associated with the part to be cooled increases and decreases as the temperature associated with the part to be cooled decreases.

[0016] In the above-mentioned centrifugal compressor, it is preferable that a bearing is provided which rotatably supports the rotating shaft relative to the housing, the part to be cooled is the bearing, and the temperature related to the part to be cooled is the temperature of the bearing.

[0017] This allows the bearing to be cooled efficiently, thereby improving the durability of the bearing. Effect of the Invention

[0018] According to the present invention, it is possible to efficiently cool the object to be cooled while avoiding a decrease in the operating efficiency of the centrifugal compressor. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view of a centrifugal compressor according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view for explaining the configuration of the first adjusting valve. [Diagram 3] FIG. 3 is a cross-sectional view for explaining the configuration of the first adjusting valve. [Figure 4] FIG. 4 is a graph for explaining the operation of the first adjusting valve. [Diagram 5] FIG. 5 is a cross-sectional view for explaining the configuration of the second adjusting valve. [Figure 6] FIG. 6 is a cross-sectional view for explaining the configuration of the second adjusting valve. [Figure 7] FIG. 7 is a graph for explaining the operation of the second adjusting valve. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a centrifugal compressor according to one embodiment will be described with reference to Fig. 1 to Fig. 7. The centrifugal compressor of this embodiment is mounted on a fuel cell vehicle. The centrifugal compressor compresses air as a fluid.

[0021] <Basic configuration of a centrifugal compressor> As shown in Fig. 1, the centrifugal compressor 10 includes a housing 11. The housing 11 is made of a metal material. For example, the housing 11 is made of 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, and a third plate 17.

[0022] The motor housing 12 has an end wall 12a and a peripheral wall 12b. The end wall 12a is plate-shaped. The peripheral wall 12b extends cylindrically from the outer periphery of the end wall 12a. The first plate 15 is connected to an end of the peripheral wall 12b of the motor housing 12 on the opening side. The first plate 15 closes the opening of the peripheral wall 12b of the motor housing 12. The motor housing 12 and the first plate 15 define a motor chamber 18. Thus, the housing 11 has the motor chamber 18.

[0023] The second plate 16 is connected to the outer surface of the end wall 12a of the motor housing 12. The second plate 16 is attached to the end wall 12a of the motor housing 12 with the thickness direction of the second plate 16 coinciding with the thickness direction of the end wall 12a of the motor housing 12.

[0024] The centrifugal compressor 10 includes a motor 20. The motor 20 is accommodated in the motor chamber 18. Thus, the motor chamber 18 accommodates the motor 20. The motor housing 12 surrounds the motor 20.

[0025] The centrifugal compressor 10 includes a first bearing retaining portion 21. The first bearing retaining portion 21 protrudes from the center of the first plate 15 into the motor chamber 18. Therefore, the first plate 15 has the first bearing retaining portion 21. The first bearing retaining portion 21 is cylindrical.

[0026] The third plate 17 is connected to the end face of the first plate 15 on the opposite side to the motor housing 12. The third plate 17 is attached to the first plate 15 with the thickness direction of the third plate 17 coinciding with the thickness direction of the first plate 15. The third plate 17 has a first insertion hole 23. The first insertion hole 23 is formed in the center of the third plate 17. The axis of the first insertion hole 23 coincides with the axis of the first bearing holder 21. The first insertion hole 23 communicates with the inside of the first bearing holder 21.

[0027] The centrifugal compressor 10 includes a second bearing retaining portion 25. The second bearing retaining portion 25 protrudes from the center of the end wall 12a of the motor housing 12 into the motor chamber 18. Therefore, the motor housing 12 has the second bearing retaining portion 25. The second bearing retaining portion 25 is cylindrical.

[0028] A second insertion hole 26 is formed in the second plate 16. The second insertion hole 26 penetrates the center of the second plate 16. The second insertion hole 26 communicates with the inside of the second bearing holder 25. The axis of the second insertion hole 26 coincides with the axis of the second bearing holder 25.

[0029] The first compressor housing 13 is cylindrical and has a first suction port 35 that is a circular hole through which air is drawn. The first compressor housing 13 is connected to an end face of the third plate 17 opposite to the first plate 15 with the axis of the first suction port 35 coinciding with the axis of the first insertion hole 23. The first suction port 35 opens at the end face of the first compressor housing 13 opposite to the third plate 17. Air that has been purified by an air cleaner (not shown) flows through the first suction port 35.

[0030] The centrifugal compressor 10 includes a first impeller chamber 36, a first discharge chamber 37, and a first diffuser passage 38. The first impeller chamber 36, the first discharge chamber 37, and the first diffuser passage 38 are formed between the first compressor housing 13 and the third plate 17. Therefore, the housing 11 has the first impeller chamber 36. The first impeller chamber 36 communicates with the first suction port 35. The first discharge chamber 37 extends around the axis of the first suction port 35 around the periphery of the first impeller chamber 36. The first diffuser passage 38 communicates between the first impeller chamber 36 and the first discharge chamber 37. The first impeller chamber 36 communicates with the first insertion hole 23.

[0031] The centrifugal compressor 10 has a first discharge passage 39. The first discharge passage 39 is formed in the first compressor housing 13. A first end of the first discharge passage 39 communicates with the first discharge chamber 37. A second end of the first discharge passage 39 opens to the outer circumferential surface of the first compressor housing 13.

[0032] The second compressor housing 14 is cylindrical and has a circular second suction port 40 through which air is drawn. The second compressor housing 14 is connected to the end face of the second plate 16 opposite the end wall 12a of the motor housing 12 with the axis of the second suction port 40 coinciding with the axis of the second insertion hole 26. The second suction port 40 opens into the end face of the second compressor housing 14 opposite the second plate 16.

[0033] The centrifugal compressor 10 includes a second impeller chamber 41, a second discharge chamber 42, and a second diffuser passage 43. The second impeller chamber 41, the second discharge chamber 42, and the second diffuser passage 43 are formed between the second compressor housing 14 and the second plate 16. Therefore, the housing 11 has the second impeller chamber 41. The second impeller chamber 41 communicates with the second suction port 40. The second discharge chamber 42 extends around the axis of the second suction port 40 around the second impeller chamber 41. The second diffuser passage 43 communicates with the second impeller chamber 41 and the second discharge chamber 42. The second impeller chamber 41 communicates with the second insertion hole 26.

[0034] The centrifugal compressor 10 has a second discharge passage 44. The second discharge passage 44 is formed in the second compressor housing 14. A first end of the second discharge passage 44 communicates with the second discharge chamber 42. A second end of the second discharge passage 44 opens to the outer circumferential surface of the second compressor housing 14.

[0035] A supply pipe 45 is connected to the second discharge passage 44. The supply pipe 45 is connected to the fuel cell stack 46. A first end of the supply pipe 45 is connected to the second discharge passage 44. A second end of the supply pipe 45 is connected to the fuel cell stack 46.

[0036] The centrifugal compressor 10 includes a connecting pipe 47. A first end of the connecting pipe 47 is connected to the first discharge passage 39. A second end of the connecting pipe 47 is connected to the second suction port 40. Air discharged from the first discharge chamber 37 to the first discharge passage 39 flows through the connecting pipe 47. The air that has passed through the connecting pipe 47 is sucked into the second impeller chamber 41 through the second suction port 40.

[0037] The centrifugal compressor 10 includes a rotating shaft 50. The rotating shaft 50 crosses inside the motor chamber 18 with the axis of the rotating shaft 50 coinciding with the axis of the peripheral wall 12b of the motor housing 12. A first end, which is one end in the axial direction of the rotating shaft 50, protrudes from inside the motor chamber 18 to the inside of the first bearing holder 21, through the first insertion hole 23, and into the first impeller chamber 36. A second end, which is the other end in the axial direction of the rotating shaft 50, protrudes from inside the motor chamber 18 to the inside of the second bearing holder 25, through the second insertion hole 26, and into the second impeller chamber 41.

[0038] The motor 20 includes a rotor 51 and a stator 52. The rotor 51 is fixed to a rotating shaft 50. The rotor 51 has a cylindrical rotor core 53 fixed to the rotating shaft 50, and a plurality of permanent magnets (not shown) provided on the rotor core 53. The rotor 51 rotates integrally with the rotating shaft 50.

[0039] The stator 52 is fixed to the motor housing 12. The stator 52 is disposed outside the rotor 51. The stator 52 has a cylindrical stator core 54 and a coil 55. The stator core 54 is fixed to the inner circumferential surface of the peripheral wall 12b of the motor housing 12. The coil 55 is wound around the stator core 54. When a current flows from a battery (not shown) to the coil 55, the rotating shaft 50 rotates integrally with the rotor 51.

[0040] The centrifugal compressor 10 includes a first dynamic pressure plain bearing 56 and a second dynamic pressure plain bearing 57. The first dynamic pressure plain bearing 56 is cylindrical. The first dynamic pressure plain bearing 56 is held by the first bearing holder 21. The first dynamic pressure plain bearing 56 supports the rotating shaft 50 rotatably relative to the first plate 15.

[0041] The second dynamic pressure plain bearing 57 is cylindrical. The second dynamic pressure plain bearing 57 is held by the second bearing holder 25. The second dynamic pressure plain bearing 57 supports the rotating shaft 50 rotatably relative to the end wall 12a of the motor housing 12. Therefore, the first dynamic pressure plain bearing 56 and the second dynamic pressure plain bearing 57 are bearings that support the rotating shaft 50 rotatably relative to the housing 11.

[0042] The centrifugal compressor 10 includes a first impeller 61 and a second impeller 62. The first impeller 61 is connected to a first end of the rotating shaft 50. The first impeller 61 is housed in the first impeller chamber 36. Therefore, the first impeller chamber 36 is an impeller chamber that houses the first impeller 61. The first impeller 61 is an impeller that rotates integrally with the rotating shaft 50 to compress the air sucked into the first impeller chamber 36.

[0043] The second impeller 62 is connected to a second end of the rotating shaft 50. The second impeller 62 is housed in the second impeller chamber 41. Therefore, the second impeller chamber 41 is an impeller chamber that houses the second impeller 62. The second impeller 62 is an impeller that rotates integrally with the rotating shaft 50 to compress the air sucked into the second impeller chamber 41. The second impeller 62 compresses the air compressed by the first impeller 61. The first impeller 61 and the second impeller 62 rotate integrally with the rotating shaft 50 to compress the air supplied to the fuel cell stack 46.

[0044] The first impeller 61 and the second impeller 62 rotate integrally with the rotary shaft 50 by being driven by the motor 20. Therefore, the motor 20 rotates the first impeller 61 and the second impeller 62.

[0045] The centrifugal compressor 10 includes a first seal member 63. The first seal member 63 is provided between the first insertion hole 23 and the rotating shaft 50. The first seal member 63 suppresses air leakage from the first impeller chamber 36 toward the inside of the motor chamber 18 via the first insertion hole 23 and the inside of the first bearing holder 21. The first seal member 63 is, for example, a seal ring.

[0046] The centrifugal compressor 10 includes a second seal member 64. The second seal member 64 is provided between the second insertion hole 26 and the rotating shaft 50. The second seal member 64 suppresses air leakage from the second impeller chamber 41 toward the inside of the motor chamber 18 via the second insertion hole 26 and the inside of the second bearing holder 25. The second seal member 64 is, for example, a seal ring.

[0047] The air drawn into the first impeller chamber 36 through the first intake port 35 is accelerated by the rotation of the first impeller 61 and sent into the first diffuser passage 38, where it is pressurized by passing through the first diffuser passage 38. The air that has passed through the first diffuser passage 38 is then discharged into the first discharge chamber 37. The air discharged into the first discharge chamber 37 is then discharged into the first discharge passage 39. The air discharged into the first discharge passage 39 is then drawn into the second impeller chamber 41 through the connecting pipe 47 and the second intake port 40. The air drawn into the second impeller chamber 41 is accelerated by the rotation of the second impeller 62 and sent into the second diffuser passage 43, where it is pressurized by passing through the second diffuser passage 43. The air that has passed through the second diffuser passage 43 is then discharged into the second discharge chamber 42. The air discharged into the second discharge chamber 42 is then discharged into the second discharge passage 44. The air discharged to the second discharge passage 44 is supplied to the fuel cell stack 46 via the supply pipe 45. Thus, the centrifugal compressor 10 supplies air to the fuel cell stack 46. The oxygen contained in the air supplied to the fuel cell stack 46 contributes to power generation in the fuel cell stack 46. The air exhausted from the fuel cell stack 46 is released into the atmosphere as exhaust gas.

[0048] The centrifugal compressor 10 includes an introduction passage 70. The introduction passage 70 includes a branch pipe 71 and an introduction hole 72. The introduction hole 72 is formed in the third plate 17. A first end of the introduction hole 72 opens to the outer circumferential surface of the third plate 17. A second end of the introduction hole 72 communicates with a portion of the first insertion hole 23 closer to the motor chamber 18 than the first seal member 63.

[0049] The branch pipe 71 branches off from the middle of the connection pipe 47. A first end of the branch pipe 71 is connected to the connection pipe 47. A second end of the branch pipe 71 is connected to a first end of the introduction hole 72. An intercooler 73 is provided in the middle of the branch pipe 71. The intercooler 73 cools the air flowing through the branch pipe 71.

[0050] The centrifugal compressor 10 includes a discharge passage 74. The discharge passage 74 is formed in the second plate 16. A first end of the discharge passage 74 communicates with a portion of the second insertion hole 26 closer to the motor chamber 18 than the second seal member 64. A second end of the discharge passage 74 opens to the outer circumferential surface of the second plate 16.

[0051] A portion of the air flowing through the connection pipe 47 flows into the branch pipe 71. The air flowing through the branch pipe 71 is cooled by the intercooler 73. Then, the air cooled by the intercooler 73 passes through the introduction hole 72, the first insertion hole 23, and the inside of the first bearing holder 21, and is introduced into the motor chamber 18. Therefore, the introduction passage 70 introduces a portion of the air compressed by the rotation of the first impeller 61 into the housing 11. The first hydrodynamic plain bearing 56 is cooled by the air passing inside the first bearing holder 21. Therefore, the first hydrodynamic plain bearing 56 is a part to be cooled arranged in the housing 11.

[0052] The air introduced into the motor chamber 18 passes between the rotor 51 and the stator 52 and flows inside the second bearing retaining portion 25. The motor 20 is cooled by the air introduced into the motor chamber 18. Therefore, the motor 20 is a part to be cooled arranged in the housing 11. The second dynamic pressure plain bearing 57 is cooled by the air passing inside the second bearing retaining portion 25. Therefore, the second dynamic pressure plain bearing 57 is a part to be cooled arranged in the housing 11. In this embodiment, the parts to be cooled arranged in the housing 11 are the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57.

[0053] In this way, the introduction passage 70 introduces into the housing 11 some of the air compressed by the rotation of the first impeller 61 in order to cool the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57, which are parts to be cooled arranged within the housing 11. The air that has passed inside the second bearing retaining portion 25 is then discharged to the outside of the housing 11 via the second insertion hole 26 and the discharge passage 74. Therefore, the discharge passage 74 discharges to the outside of the housing 11 the air that has been introduced from the introduction passage 70 into the housing 11 and has cooled the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57, which are parts to be cooled.

[0054] <First adjustment valve> The introduction passage 70 is provided with a first regulating valve 75 and a second regulating valve 76. The first regulating valve 75 and the second regulating valve 76 are provided in the introduction hole 72. Therefore, the first regulating valve 75 and the second regulating valve 76 are buried in the housing 11 by being provided in the introduction hole 72. The first regulating valve 75 and the second regulating valve 76 are arranged in series with respect to the introduction hole 72. The first regulating valve 75 is arranged closer to the branch pipe 71 than the second regulating valve 76. Therefore, the first regulating valve 75 is located upstream of the second regulating valve 76 in the flow direction of the air flowing through the introduction passage 70.

[0055] An intake hole 77 is formed in the third plate 17. A first end of the intake hole 77 opens to the outer circumferential surface of the third plate 17. A second end of the intake hole 77 communicates with the introduction hole 72.

[0056] As shown in FIG. 2 and FIG. 3, the first adjusting valve 75 has a valve casing 78, a first valve body 79, and a biasing spring 80. The valve casing 78 is cylindrical. The valve casing 78 is fixed to the inner wall of the third plate 17 that forms the introduction hole 72. The internal space of the valve casing 78 constitutes a part of the introduction passage 70. The valve casing 78 has a first communication hole 78a and a second communication hole 78b. The first communication hole 78a communicates between the internal space of the valve casing 78 and a portion of the introduction hole 72 downstream of the valve casing 78. The second communication hole 78b communicates with the intake hole 77. The valve casing 78 has a valve hole 78h. Air flowing into the internal space of the valve casing 78 from the portion of the inlet hole 72 upstream of the valve casing 78 flows into the portion of the inlet hole 72 downstream of the valve casing 78 via the valve hole 78h and the first communication hole 78a.

[0057] The first valve body 79 is accommodated in the valve casing 78 so as to be capable of reciprocating in the axial direction of the valve casing 78. The first valve body 79 has a valve portion 79a, a piston portion 79b, and a connection portion 79c. The connection portion 79c is columnar. The first valve body 79 is accommodated in the valve casing 78 with the axial direction of the connection portion 79c coinciding with the axial direction of the valve casing 78. The valve portion 79a is connected to a first end of the connection portion 79c. The piston portion 79b is connected to a second end of the connection portion 79c. The connection portion 79c passes through the valve hole 78h.

[0058] The piston portion 79b has a first pressure receiving surface 791 and a second pressure receiving surface 792. The first pressure receiving surface 791 is a surface located on one side of the axial direction of the connecting portion 79c of the piston portion 79b. The second pressure receiving surface 792 is a surface located on the other side of the axial direction of the connecting portion 79c of the piston portion 79b. The connecting portion 79c protrudes from the first pressure receiving surface 791. The first pressure receiving surface 791 receives the pressure of air flowing into the internal space of the valve casing 78 from a portion of the introduction hole 72 upstream of the valve casing 78. The second pressure receiving surface 792 receives atmospheric pressure, which is the pressure of air taken into the intake hole 77 from the outside of the housing 11 and flowing into the valve casing 78 through the second communication hole 78b. The first valve body 79 is capable of reciprocating within the valve casing 78 based on the pressure difference between the pressure of the air received by the first pressure receiving surface 791 and the pressure of the air received by the second pressure receiving surface 792. The gap between the piston portion 79b and the inner circumferential surface of the valve casing 78 is sealed by a seal member 78s.

[0059] The valve portion 79a is configured to be able to open and close the valve hole 78h by the first valve body 79 reciprocating within the valve casing 78. The first adjusting valve 75 is configured to be able to switch between an open state in which the valve portion 79a opens the valve hole 78h and a closed state in which the valve portion 79a closes the valve hole 78h. The first adjusting valve 75 increases its valve opening degree by the first valve body 79 moving in a direction in which the valve portion 79a opens the valve hole 78h. The first adjusting valve 75 decreases its valve opening degree by the first valve body 79 moving in a direction in which the valve portion 79a closes the valve hole 78h.

[0060] The biasing spring 80 is interposed between the second pressure receiving surface 792 of the piston portion 79b and the inner surface of the valve casing 78. The biasing spring 80 biases the first valve body 79 in a direction in which the valve portion 79a opens the valve hole 78h.

[0061] FIG. 4 shows the relationship between the pressure difference between the air pressure received by the first pressure receiving surface 791 and the air pressure received by the second pressure receiving surface 792 and the valve opening degree of the first adjusting valve 75. As shown in FIG. 4, as the pressure difference between the air pressure received by the first pressure receiving surface 791 and the air pressure received by the second pressure receiving surface 792 becomes smaller, the valve opening degree of the first adjusting valve 75 becomes larger. Specifically, as shown in FIG. 3, when the pressure difference between the air pressure received by the first pressure receiving surface 791 and the air pressure received by the second pressure receiving surface 792 becomes smaller, the first valve body 79 moves in a direction in which the valve portion 79a opens the valve hole 78h due to the biasing force of the biasing spring 80. As a result, the valve opening degree of the first adjusting valve 75 becomes larger. When the valve opening degree becomes larger, the first adjusting valve 75 increases the passage cross-sectional area of ​​the introduction passage 70.

[0062] On the other hand, as shown in Fig. 4, the valve opening degree of the first adjusting valve 75 decreases as the pressure difference between the pressure of the air received by the first pressure receiving surface 791 and the pressure of the air received by the second pressure receiving surface 792 increases. Specifically, as shown in Fig. 2, when the pressure difference between the pressure of the air received by the first pressure receiving surface 791 and the pressure of the air received by the second pressure receiving surface 792 increases, the pressure of the air received by the first pressure receiving surface 791 resists the biasing force of the biasing spring 80, so that the first valve body 79 moves in a direction in which the valve portion 79a closes the valve hole 78h. As a result, the valve opening degree of the first adjusting valve 75 decreases. When the valve opening degree decreases, the first adjusting valve 75 reduces the passage cross-sectional area of ​​the introduction passage 70.

[0063] The pressure of the air received by the first pressure receiving surface 791 is the discharge pressure of the air compressed by the rotation of the first impeller 61. The pressure of the air received by the second pressure receiving surface 792 is atmospheric pressure. Therefore, the first adjusting valve 75 increases the valve opening degree as the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure decreases, thereby increasing the passage cross-sectional area of ​​the introduction passage 70. Also, the first adjusting valve 75 decreases the valve opening degree as the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure increases, thereby decreasing the passage cross-sectional area of ​​the introduction passage 70.

[0064] <Second Adjustment Valve> As shown in Figures 5 and 6, the second adjustment valve 76 has a valve casing 81, a second valve body 82, a biasing spring 84, and a temperature sensor 85. The valve casing 81 is cylindrical. The valve casing 81 is fixed to the inner wall of the third plate 17 that forms the introduction hole 72. The internal space of the valve casing 81 constitutes a part of the introduction passage 70. The second valve body 82 is accommodated in the valve casing 81 so as to be able to reciprocate in the axial direction of the valve casing 81.

[0065] The valve casing 81 has a valve hole 83. The second valve body 82 is configured to be able to open and close the valve hole 83 by reciprocating within the valve casing 81. The second adjusting valve 76 is configured to be able to switch between an open state in which the second valve body 82 opens the valve hole 83, and a closed state in which the second valve body 82 closes the valve hole 83. The biasing spring 84 biases the second valve body 82 in a direction in which the second valve body 82 closes the valve hole 83.

[0066] The temperature sensor 85 is housed in the valve casing 81. The temperature sensor 85 has a temperature sensor member 86 and a support member 87. The support member 87 supports the temperature sensor member 86 in the valve casing 81. The temperature sensor member 86 is columnar. The temperature sensor member 86 is configured to be able to protrude and retract from the support member 87. Heat from the first hydrodynamic pressure sliding bearing 56 can be transferred to the temperature sensor member 86 via the first plate 15, the third plate 17, and the valve casing 81. The temperature sensor member 86 protrudes more from the support member 87 as the temperature of the heat transferred to the temperature sensor 85 via the first plate 15, the third plate 17, and the valve casing 81 increases. The temperature sensor member 86 is configured to be able to press the second valve body 82 so that the valve opening of the second adjustment valve 76 increases as the protrusion from the support member 87 increases. The temperature-sensing member 86 is capable of pressing the second valve body 82 in a direction in which the second valve body 82 opens the valve hole 83, against the biasing force of the biasing spring 84. In this way, the second adjusting valve 76 is a temperature-sensing valve in which the valve opening degree changes autonomously as a result of the temperature-sensing body 85 operating due to the transfer of heat from the first hydrodynamic bearing 56.

[0067] 7 shows the relationship between the temperature of the first hydrodynamic bearing 56 and the valve aperture of the second adjusting valve 76. As shown in FIG. 7, as the temperature of the first hydrodynamic bearing 56 increases, the valve aperture of the second adjusting valve 76 increases. Specifically, as shown in FIG. 5, as the temperature of the first hydrodynamic bearing 56 increases, the amount of protrusion of the temperature-sensitive member 86 from the support member 87 increases, and the temperature-sensitive member 86 presses the second valve body 82 in a direction in which the second valve body 82 opens the valve hole 83 against the biasing force of the biasing spring 84. This increases the valve aperture of the second adjusting valve 76. As the valve aperture increases, the second adjusting valve 76 increases the passage cross-sectional area of ​​the introduction passage 70.

[0068] On the other hand, as shown in Fig. 7, as the temperature of the first hydrodynamic bearing 56 decreases, the valve opening of the second adjustment valve 76 decreases. Specifically, as shown in Fig. 6, as the temperature of the first hydrodynamic bearing 56 decreases, the amount of protrusion of the temperature-sensitive member 86 from the support member 87 decreases, and the biasing force of the biasing spring 84 moves the second valve body 82 in a direction to close the valve hole 83. This reduces the valve opening of the second adjustment valve 76. The second adjustment valve 76 reduces the passage cross-sectional area of ​​the introduction passage 70 as the valve opening decreases.

[0069] Therefore, as the temperature associated with the first dynamic pressure plain bearing 56, which is the part to be cooled, increases, the second adjusting valve 76 increases its valve opening, thereby increasing the passage cross-sectional area of ​​the introduction passage 70. Also, as the temperature associated with the first dynamic pressure plain bearing 56, which is the part to be cooled, decreases, the second adjusting valve 76 decreases its valve opening, thereby decreasing the passage cross-sectional area of ​​the introduction passage 70. Thus, in this embodiment, the temperature associated with the part to be cooled is the temperature of the first dynamic pressure plain bearing 56.

[0070] [Operation of the embodiment] Next, the operation of the embodiment will be described. Incidentally, the pressure inside the housing 11 is equal to atmospheric pressure because the housing 11 is connected to the outside of the housing 11 via the discharge passage 74. The flow rate of air introduced into the housing 11 via the introduction passage 70 increases as the pressure difference between the atmospheric pressure and the discharge pressure of the air compressed by the rotation of the first impeller 61 increases.

[0071] As the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure increases, the first adjusting valve 75 reduces the valve opening to reduce the passage cross-sectional area of ​​the introduction passage 70. Therefore, when the pressure difference between the discharge pressure of the air and the atmospheric pressure is large and the flow rate of air introduced into the housing 11 through the introduction passage 70 is large, the first adjusting valve 75 reduces the passage cross-sectional area of ​​the introduction passage 70. This prevents a portion of the air compressed by the rotation of the first impeller 61 from being excessively introduced into the housing 11 through the introduction passage 70.

[0072] Here, for example, when the centrifugal compressor 10 is operated in an environment with low atmospheric pressure, such as a high altitude region, the suction pressure of the air drawn into the first impeller chamber 36 also decreases with the decrease in atmospheric pressure. Then, when the pressure ratio of the centrifugal compressor 10 is constant, the discharge pressure of the air compressed by the rotation of the first impeller 61 also decreases. As a result, the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure decreases.

[0073] At this time, the first adjusting valve 75 increases its valve opening to increase the passage cross-sectional area of ​​the introduction passage 70. And, as the temperature of the first dynamic pressure plain bearing 56 increases, the second adjusting valve 76 increases its valve opening to increase the passage cross-sectional area of ​​the introduction passage 70. According to this, when the temperature of the first dynamic pressure plain bearing 56 is high and there is a high need to cool the first dynamic pressure plain bearing 56, the flow rate of air introduced into the housing 11 via the introduction passage 70 increases even if the pressure difference between the air discharge pressure and atmospheric pressure decreases. Therefore, the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are sufficiently cooled by the air introduced into the housing 11 via the introduction passage 70.

[0074] On the other hand, when the centrifugal compressor 10 is operating, for example, in a low load state, the temperatures of the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are low, so that the need for cooling the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 is low. Here, when the centrifugal compressor 10 is operating in a low load state, the pressure ratio of the centrifugal compressor 10 is low. Therefore, when the centrifugal compressor 10 is operating in a low load state, the discharge pressure of the air compressed by the rotation of the first impeller 61 is low. For this reason, the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure becomes small, so that the first regulating valve 75 increases the valve opening degree and increases the passage cross-sectional area of ​​the introduction passage 70. At this time, the second regulating valve 76 decreases the valve opening degree as the temperature of the first dynamic pressure plain bearing 56 decreases, thereby decreasing the passage cross-sectional area of ​​the introduction passage 70. Therefore, when the temperatures of the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are low and there is little need to cool the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57, it is possible to prevent an excessive amount of the air compressed by the rotation of the first impeller 61 from being introduced into the housing 11 through the inlet passage 70.

[0075] [Effects of the embodiment] The embodiment can provide the following effects. (1) The first regulating valve 75 reduces the valve opening and the passage cross-sectional area of ​​the introduction passage 70 as the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure increases. Therefore, the first regulating valve 75 reduces the passage cross-sectional area of ​​the introduction passage 70 when the pressure difference between the discharge pressure of the air and the atmospheric pressure is large and the flow rate of the air introduced into the housing 11 through the introduction passage 70 is large. This makes it possible to prevent a part of the air compressed by the rotation of the first impeller 61 from being excessively introduced into the housing 11 through the introduction passage 70. As a result, it is possible to avoid a decrease in the operating efficiency of the centrifugal compressor 10.

[0076] Also, for example, when the centrifugal compressor 10 is operated in an environment where the atmospheric pressure is low, the suction pressure of the air drawn into the first impeller chamber 36 also decreases with the decrease in the atmospheric pressure. Then, when the pressure ratio of the centrifugal compressor 10 is constant, the discharge pressure of the air compressed by the rotation of the first impeller 61 also decreases. As a result, the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure decreases. At this time, the first regulating valve 75 increases its valve opening to increase the passage cross-sectional area of ​​the introduction passage 70. Then, the second regulating valve 76 increases its valve opening to increase the passage cross-sectional area of ​​the introduction passage 70 as the temperature of the first hydrodynamic bearing 56 increases. According to this, when the temperatures of the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are high and there is a high need to cool the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57, it is possible to increase the flow rate of air introduced into the housing 11 via the introduction passage 70 even if the differential pressure between the air discharge pressure and atmospheric pressure becomes small. Therefore, the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 can be sufficiently cooled by the air introduced into the housing 11 via the introduction passage 70.

[0077] On the other hand, when the centrifugal compressor 10 is operating, for example, in a low load state, the temperatures of the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are low, so that the need for cooling the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 is low. Here, when the centrifugal compressor 10 is operating in a low load state, the pressure ratio of the centrifugal compressor 10 is low. Therefore, when the centrifugal compressor 10 is operating in a low load state, the discharge pressure of the air compressed by the rotation of the first impeller 61 is low. For this reason, the pressure difference between the discharge pressure of the air compressed by the rotation of the first impeller 61 and the atmospheric pressure becomes small, so that the first regulating valve 75 increases the valve opening degree and increases the passage cross-sectional area of ​​the introduction passage 70. At this time, the second regulating valve 76 decreases the valve opening degree as the temperature of the first dynamic pressure plain bearing 56 decreases, thereby decreasing the passage cross-sectional area of ​​the introduction passage 70. Therefore, when the temperatures of the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 are low and there is little need to cool the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57, it is possible to prevent a portion of the air compressed by the rotation of the first impeller 61 from being excessively introduced into the housing 11 via the introduction passage 70. As a result, it is possible to avoid a decrease in the operating efficiency of the centrifugal compressor 10. As a result, it is possible to efficiently cool the first dynamic pressure plain bearing 56, the motor 20, and the second dynamic pressure plain bearing 57 while avoiding a decrease in the operating efficiency of the centrifugal compressor 10.

[0078] (2) Because the first adjusting valve 75 and the second adjusting valve 76 are embedded in the housing 11, there is no need to provide space for providing the first adjusting valve 75 and the second adjusting valve 76 around the outside of the housing 11. Therefore, part of the space around the outside of the housing 11 is not used as the arrangement space for the first adjusting valve 75 and the second adjusting valve 76, and the space around the outside of the housing 11 can be effectively used as the arrangement space for other parts provided around the outside of the housing 11.

[0079] (3) The second adjusting valve 76 has a temperature sensor 85. Heat from the first hydrodynamic plain bearing 56 can be transferred to the temperature sensor 85 via the housing 11. The second adjusting valve 76 changes its valve opening autonomously as the temperature sensor 85 operates in response to the transfer of heat from the first hydrodynamic plain bearing 56. This configuration is suitable for the second adjusting valve 76 that is embedded within the housing 11 and in which the valve opening increases as the temperature of the first hydrodynamic plain bearing 56 increases and decreases as the temperature of the first hydrodynamic plain bearing 56 decreases.

[0080] (4) The temperature associated with the part to be cooled is the temperature of the first dynamic pressure sliding bearing 56. This makes it possible to efficiently cool the first dynamic pressure sliding bearing 56 and the second dynamic pressure sliding bearing 57, thereby improving the durability of the first dynamic pressure sliding bearing 56 and the second dynamic pressure sliding bearing 57.

[0081] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0082] In the embodiment, the first adjusting valve 75 and the second adjusting valve 76 may be provided in the branch pipe 71 instead of in the inlet hole 72. In short, it is only necessary that the first adjusting valve 75 and the second adjusting valve 76 are provided in the inlet passage 70.

[0083] In the embodiment, the second adjusting valve 76 may be configured, for example, so that the valve opening degree increases as the temperature in the motor chamber 18 increases and decreases as the temperature in the motor chamber 18 decreases. The temperature in the motor chamber 18 is related to the temperature of the motor 20. In this manner, the second adjusting valve 76 may be configured so that the valve opening degree increases as the temperature related to the motor 20, which is the part to be cooled, increases and the valve opening degree decreases as the temperature related to the motor 20 decreases.

[0084] In the embodiment, the second adjusting valve 76 may be a solenoid valve that is driven by an external current. In this case, it is not necessary for the heat of the first hydrodynamic plain bearing 56 to be transferable to the temperature sensor 85 via the housing 11. The second adjusting valve 76 may be configured so that the valve opening degree of the second adjusting valve 76 is adjusted by electrically controlling the drive of the second adjusting valve 76 based on the temperature of the first hydrodynamic plain bearing 56. In short, the specific configuration of the second adjusting valve 76 is not particularly limited as long as it is configured to operate based on a temperature associated with the part to be cooled.

[0085] In the embodiment, the intake hole 77 does not have to be formed in the third plate 17. In this case, the first adjusting valve 75 may be configured so that the air pressure from inside the motor chamber 18 is received by the second pressure receiving surface 792 of the first valve body 79. In short, the specific configuration of the first adjusting valve 75 is not particularly limited as long as it is configured to operate based on the differential pressure between the discharge pressure of the air compressed by rotation of the impeller and atmospheric pressure.

[0086] In the above embodiment, the second adjusting valve 76 may be located upstream of the first adjusting valve 75 in the flow direction of the air flowing through the introduction passage 70. In the embodiment, the introduction hole 72 of the introduction passage 70 may be formed in the second plate 16. In this case, the second adjustment valve 76 changes its valve opening autonomously as the temperature sensor 85 operates due to the transfer of heat from the second dynamic pressure plain bearing 57. Therefore, the temperature associated with the part to be cooled is the temperature of the second dynamic pressure plain bearing 57.

[0087] In the above embodiment, the intercooler 73 does not necessarily have to be provided in the middle of the branch pipe 71 . In the above embodiment, the introduction passage 70 may introduce part of the air compressed by the second impeller 62 into the housing 11.

[0088] In the above embodiment, the centrifugal compressor 10 does not have to include the second impeller 62. In the above-mentioned embodiment, the centrifugal compressor 10 may be configured to include a turbine wheel instead of the second impeller 62.

[0089] In the above-mentioned embodiment, the centrifugal compressor 10 does not have to be mounted on a fuel cell vehicle. In other words, the centrifugal compressor 10 is not limited to being mounted on a vehicle. In the above-described embodiment, the centrifugal compressor 10 is not limited to be used for compressing the air supplied to the fuel cell stack 46. In short, the centrifugal compressor 10 may be used for compressing a fluid. [Explanation of symbols]

[0090] Reference Signs List of Drawings 10...centrifugal compressor, 11...housing, 20...motor (part to be cooled), 36...first impeller chamber which is an impeller chamber, 41...second impeller chamber which is an impeller chamber, 50...rotating shaft, 56...first dynamic pressure plain bearing which is a bearing (part to be cooled), 57...second dynamic pressure plain bearing which is a bearing (part to be cooled), 61...first impeller which is an impeller, 62...second impeller which is an impeller, 70...introduction passage, 72...introduction hole, 74...discharge passage, 75...first adjusting valve, 76...second adjusting valve, 85...temperature sensor.

Claims

1. A rotation axis; an impeller that rotates integrally with the rotary shaft to compress a fluid; a housing having an impeller chamber for accommodating the impeller; an introduction passage for introducing a part of the fluid compressed by the rotation of the impeller into the housing in order to cool a cooling target disposed in the housing; a discharge passage for discharging the fluid introduced from the introduction passage into the housing and used to cool the cooling target to the outside of the housing, The introduction passage includes: a first regulating valve that increases a valve opening degree as a pressure difference between a discharge pressure of the fluid compressed by rotation of the impeller and atmospheric pressure decreases, thereby increasing a passage cross-sectional area of ​​the introduction passage, and decreases a valve opening degree as the pressure difference increases, thereby decreasing the passage cross-sectional area; a second adjusting valve that increases a valve opening degree to increase the passage cross-sectional area as a temperature associated with the cooling target increases, and decreases a valve opening degree to decrease the passage cross-sectional area as the temperature decreases, The centrifugal compressor according to claim 1, wherein the first regulating valve and the second regulating valve are disposed in series with respect to the inlet passage.

2. The introduction passage has an introduction hole formed in the housing, 2. The centrifugal compressor according to claim 1, wherein the first regulating valve and the second regulating valve are provided in the inlet hole and are embedded in the housing.

3. The second adjusting valve has a temperature sensor, The heat of the cooling target can be transferred to the temperature sensor through the housing, 3. The centrifugal compressor according to claim 2, wherein the second adjusting valve autonomously changes a valve opening degree in response to the operation of the temperature sensor by heat transfer from the object to be cooled.

4. a bearing that rotatably supports the rotating shaft relative to the housing, the cooling target is the bearing, 4. The centrifugal compressor according to claim 1, wherein the temperature related to the part to be cooled is a temperature of the bearing.

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