JP2020056321A - Centrifugal compressor - Google Patents

Abstract

To prevent a shortage of oil to be supplied to a speed-up gear while curbing an increase in pressure in a speed-up gear chamber.SOLUTION: In a state where operation of a centrifugal compressor 10 is stopped, a valve body 63 is moved in a direction to close a second connection passage 56b of an oil supply passage 56 by energizing force of an energizing spring 64 so as to allow a speed-up gear chamber 13c to be communicated with an outside through a bypass passage 61, a buffer chamber 60b and a discharge hole 60c. When the centrifugal compressor 10 is in operation, the valve 63 is moved in the direction to open the second connection passage 56b of the oil supply passage 56 and close the bypass passage 61 against the energizing force of the energizing spring 64 with a pressure receiving surface 63a of the valve body 63 subject to hydrodynamic pressure of oil which is discharged from an oil pump 57 and flows in a second connection passage 56b of the oil supply passage 56. Thus, communication of the speed-up gear chamber 13c with the outside through the bypass passage 61 is closed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a centrifugal compressor.

  The centrifugal compressor includes a low-speed shaft, an impeller that rotates together with the high-speed shaft and compresses gas, and a gearbox that transmits power of the low-speed shaft to the high-speed shaft. In the housing of the centrifugal compressor, an impeller chamber for accommodating the impeller and a gearbox for accommodating the gearbox are formed. The impeller room and the gearbox room are separated by a partition wall. A shaft insertion hole is formed in the partition wall. The high-speed shaft protrudes into the impeller chamber from the gearbox room through the shaft insertion hole.

  In such a centrifugal compressor, oil is supplied to the speed increasing device, for example, as disclosed in Patent Document 1, in order to suppress friction and seizure of a sliding portion between the high speed side shaft and the speed increasing device. The centrifugal compressor includes an oil pan in which oil supplied to the gearbox is stored, an oil supply passage for supplying the oil stored in the oil pan to the gearbox, and oil in the gearbox. An oil return passage for returning to the pan. Then, the oil supplied from the oil pan to the gearbox via the oil supply passage is supplied to the gearbox, then stored in the gearbox, and returned to the oil pan via the oil return passage. You. A seal member is provided between the outer peripheral surface of the high-speed shaft and the inner peripheral surface of the shaft insertion hole. The seal member suppresses oil stored in the gearbox room from leaking into the impeller chamber through the shaft insertion hole.

JP-A-2006-186238

  However, when the gas is compressed with the rotation of the impeller and the pressure in the impeller chamber increases, the impeller chamber passes through the space between the outer peripheral surface of the high-speed shaft and the inner peripheral surface of the shaft insertion hole to move into the gearbox room. Gas may leak and the pressure inside the gearbox may increase. When the pressure in the impeller chamber becomes lower than the pressure in the gear box, for example, when the impeller is rotating at a low speed or when the operation of the centrifugal compressor is stopped, the pressure increases. There is a possibility that the oil in the gearbox may leak into the impeller chamber via the space between the outer circumferential surface of the high-speed shaft and the inner circumferential surface of the shaft insertion hole.

  Therefore, in order to suppress an increase in the pressure in the gearbox, for example, it is conceivable to provide a depressurizing passage for communicating the oil pan with the outside in the centrifugal compressor. Here, for example, when the operation of the centrifugal compressor is stopped, the oil supply passage and the oil recirculation passage are filled with oil, so that the interior of the gear box becomes a closed space. Then, for example, when the temperature inside the gearbox increases due to, for example, a vehicle equipped with the centrifugal compressor receiving insolation, the gas inside the gearbox expands due to the expansion of the gas inside the gearbox. The gas is pushed out by the gas and flows out to the oil return passage, and the oil flows into the oil pan via the oil return passage, so that the oil level of the oil pan rises. As the oil level of the oil pan rises, oil may leak out of the depressurization passage to the outside, and the amount of oil supplied to the gearbox will decrease.

  The present invention has been made to solve the above problem, and an object of the present invention is to reduce the amount of oil supplied to the gearbox while suppressing an increase in pressure in the gearbox. It is an object of the present invention to provide a centrifugal compressor capable of suppressing such a problem.

  A centrifugal compressor for solving the above-mentioned problems includes a low-speed side shaft, an impeller that rotates integrally with the high-speed side shaft and compresses gas, a speed-increasing device that transmits power of the low-speed side shaft to the high-speed side shaft, An impeller chamber for accommodating the impeller, and a housing in which a gearbox for accommodating the gearbox is formed; a partition wall for partitioning the impeller chamber and the gearbox; and a partition wall formed on the partition wall. A shaft insertion hole through which the high-speed shaft is inserted, a seal member provided between an outer peripheral surface of the high-speed shaft and an inner peripheral surface of the shaft insertion hole, and an oil supplied to the gear box An oil pan, an oil supply passage for supplying oil stored in the oil pan to the gearbox, an oil return passage for returning oil in the gearbox to the oil pan, A centrifugal compressor having a pressure relief passage communicating between the oil pan and the outside, a bypass passage having one end communicating with the speed increasing chamber and the other end communicating with the outside, and the oil supply passage. An oil pump for sucking up and discharging the oil stored in the oil pan and having one end communicating with a portion of the oil supply passage closer to the discharge side than the oil pump, and the other end communicating with the bypass passage. A communication path, a valve element slidably disposed in the communication path, and an urging member for urging the valve element toward the oil supply path side to shut off the oil supply path, When the valve element receives the dynamic pressure of the oil discharged from the oil pump, the valve element moves against the urging force of the urging member to open the oil supply passage and to bypass the oil supply passage. Blocking the road.

  According to this, for example, when the operation of the centrifugal compressor is stopped, the driving of the oil pump is stopped, and the valve body does not receive the dynamic pressure of the oil. The urging force moves the oil supply passage in a direction to shut off the oil supply passage, and communication between the gearbox room and the outside via the bypass passage is allowed. Therefore, even when the oil supply passage and the oil return passage are filled with oil while the operation of the centrifugal compressor is stopped, the interior of the gear box does not become a closed space. As a result, even if the temperature inside the gearbox room rises and the gas inside the gearbox room expands, the gas inside the gearbox room is discharged to the outside through the bypass passage. It is possible to prevent the oil from being pushed out by the gas and flowing out into the oil return passage, and the oil from flowing into the oil pan via the oil return passage. Therefore, since the rise in the oil level of the oil pan can be suppressed, the leakage of the oil from the pressure release passage to the outside due to the rise in the oil level of the oil pan can be suppressed, and the amount of oil supplied to the gearbox is reduced. Can be suppressed.

  Also, during the operation of the centrifugal compressor, even if gas leaks from the impeller chamber to the gear box through the space between the outer circumferential surface of the high-speed shaft and the inner circumferential surface of the shaft insertion hole, the speed increase Since the gas in the cabin is discharged to the outside from the depressurizing passage via the oil recirculation passage and the oil pan, an increase in the pressure in the gearbox is suppressed. Further, during operation of the centrifugal compressor, the valve body receives the dynamic pressure of the oil discharged from the oil pump, moves against the urging force of the urging member, opens the oil supply passage, and bypasses the oil supply passage. Block passage. Therefore, even if the oil in the gearbox room stirred by the gearbox during the operation of the centrifugal compressor flows into the bypass passage, it is possible to suppress the oil from leaking out through the bypass passage. Therefore, even if the centrifugal compressor is provided with the bypass passage, it is possible to prevent the amount of oil supplied to the gearbox from decreasing. From the above, it is possible to suppress a decrease in the amount of oil supplied to the gearbox, while suppressing an increase in pressure in the gearbox room.

  A centrifugal compressor for solving the above-mentioned problems includes a low-speed side shaft, an impeller that rotates integrally with the high-speed side shaft and compresses gas, a speed-increasing device that transmits power of the low-speed side shaft to the high-speed side shaft, An impeller chamber for accommodating the impeller, and a housing in which a gearbox for accommodating the gearbox is formed; a partition wall for partitioning the impeller chamber and the gearbox; and a partition wall formed on the partition wall. A shaft insertion hole through which the high-speed shaft is inserted, a seal member provided between an outer peripheral surface of the high-speed shaft and an inner peripheral surface of the shaft insertion hole, and an oil supplied to the gear box An oil pan, an oil supply passage for supplying oil stored in the oil pan to the gearbox, an oil return passage for returning oil in the gearbox to the oil pan, A centrifugal compressor having a pressure relief passage communicating the oil pan with the outside, a bypass passage having one end communicating with the speed increaser chamber and the other end communicating with the outside, and one end having the impeller. A communication passage communicating with a position facing the back surface of the impeller in the chamber, the other end of which communicates with the bypass passage, a valve element slidably disposed in the communication passage, and opening the bypass passage. An urging member that urges the valve element toward the communication path, wherein the valve element opposes the urging force of the urging member when receiving a back pressure generated on the back side of the impeller. It moves and shuts off the bypass passage.

  According to this, for example, in a state where the operation of the centrifugal compressor is stopped, the valve body does not receive the back pressure which is the pressure generated on the back side of the impeller in the impeller chamber. The urging force moves in a direction to open the bypass passage, and communication between the gearbox room and the outside via the bypass passage is allowed. Therefore, even when the oil supply passage and the oil return passage are filled with oil while the operation of the centrifugal compressor is stopped, the interior of the gear box does not become a closed space. As a result, even if the temperature inside the gearbox room rises and the gas inside the gearbox room expands, the gas inside the gearbox room is discharged to the outside via the bypass passage, so that the inside of the gearbox room is increased. It is possible to prevent the oil from being pushed out by the gas and flowing out into the oil return passage, and the oil from flowing into the oil pan via the oil return passage. Therefore, since the rise in the oil level of the oil pan can be suppressed, the leakage of the oil from the pressure release passage to the outside due to the rise in the oil level of the oil pan can be suppressed, and the amount of oil supplied to the gearbox is reduced. Can be suppressed.

  Also, during the operation of the centrifugal compressor, even if gas leaks from the impeller chamber to the gear box through the space between the outer circumferential surface of the high-speed shaft and the inner circumferential surface of the shaft insertion hole, the speed increase Since the gas in the cabin is discharged to the outside from the depressurizing passage via the oil recirculation passage and the oil pan, an increase in the pressure in the gearbox is suppressed. Further, during the operation of the centrifugal compressor, the valve body receives the back pressure generated on the back side of the impeller chamber, and moves against the urging force of the urging member to shut off the bypass passage. Therefore, even if the oil in the gearbox room stirred by the gearbox during the operation of the centrifugal compressor flows into the bypass passage, it is possible to suppress the oil from leaking out through the bypass passage. Therefore, even if the centrifugal compressor is provided with the bypass passage, it is possible to prevent the amount of oil supplied to the gearbox from decreasing. From the above, it is possible to suppress a decrease in the amount of oil supplied to the gearbox, while suppressing an increase in pressure in the gearbox room.

  According to the present invention, it is possible to suppress a decrease in the amount of oil supplied to the gearbox while suppressing an increase in pressure in the gearbox.

FIG. 2 is a side sectional view showing the centrifugal compressor according to the first embodiment. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. Sectional drawing which expands and shows the valve closing state of a valve body. Sectional drawing which expands and shows the valve-open state of a valve body. The sectional side view showing the centrifugal compressor in a 2nd embodiment. Sectional drawing which expands and shows the valve closing state of a valve body. Sectional drawing which expands and shows the valve-open state of a valve body.

(First embodiment)
Hereinafter, a first embodiment that embodies a centrifugal compressor will be described with reference to FIGS. The centrifugal compressor of the present embodiment is mounted on a fuel cell vehicle (FCV) that runs using a fuel cell as a power source, and supplies air to the fuel cell.

  As shown in FIG. 1, a housing 11 of the centrifugal compressor 10 includes a motor housing 12, a gearbox housing 13 connected to the motor housing 12, a plate 14 connected to the gearbox housing 13, and a plate 14. And a compressor housing 15 connected to the compressor housing 15. The motor housing 12, the gearbox housing 13, the plate 14, and the compressor housing 15 are made of a metal material formed of, for example, aluminum. The housing 11 is substantially cylindrical. The motor housing 12, the gearbox housing 13, the plate 14, and the compressor housing 15 are arranged in this order in the axial direction of the housing 11.

  The motor housing 12 has a bottomed cylindrical shape having a disc-shaped bottom wall 12a and a peripheral wall 12b extending cylindrically from the outer peripheral edge of the bottom wall 12a. The gear box housing 13 has a bottomed cylindrical shape having a disc-shaped bottom wall 13a and a peripheral wall 13b extending cylindrically from the outer peripheral edge of the bottom wall 13a.

  An end of the peripheral wall 12b of the motor housing 12 opposite to the bottom wall 12a is connected to a bottom wall 13a of the speed increaser housing 13. An opening of the peripheral wall 12 b of the motor housing 12 on the opposite side to the bottom wall 12 a is closed by a bottom wall 13 a of the speed increasing housing 13. A through hole 13h is formed in the center of the bottom wall 13a.

  The end of the peripheral wall 13b of the speed-up gear housing 13 on the opposite side to the bottom wall 13a is connected to the plate 14. An opening of the peripheral wall 13 b of the speed-increasing gear housing 13 on the opposite side to the bottom wall 13 a is closed by a plate 14. A shaft insertion hole 14h is formed in the center of the plate 14.

  The compressor housing 15 is connected to a surface of the plate 14 on a side opposite to the gear box housing 13. The compressor housing 15 has a suction port 15a through which air, which is a gas, is sucked. The suction port 15a opens at the center of the end face of the compressor housing 15 opposite to the plate 14, and extends in the axial direction of the housing 11 from the center of the end face of the compressor housing 15 opposite to the plate 14. .

  The centrifugal compressor 10 includes a low-speed side shaft 16 and an electric motor 17 for rotating the low-speed side shaft 16. In the housing 11, a motor chamber 12c that houses the electric motor 17 is formed. The motor chamber 12c is defined by the inner surface of the bottom wall 12a of the motor housing 12, the inner peripheral surface of the peripheral wall 12b, and the outer surface of the bottom wall 13a of the gearbox housing 13. The low-speed side shaft 16 is accommodated in the motor housing 12 in a state where the axial direction of the low-speed side shaft 16 matches the axial direction of the motor housing 12. The low-speed side shaft 16 is made of, for example, a metal material formed of iron or an alloy.

  A cylindrical boss 12f protrudes from the inner surface of the bottom wall 12a of the motor housing 12. One end of the low-speed shaft 16 is inserted into the boss 12f. A first bearing 18 is provided between one end of the low-speed shaft 16 and the boss 12f. One end of the low-speed shaft 16 is rotatably supported on the bottom wall 12 a of the motor housing 12 via the first bearing 18.

  The other end of the low-speed shaft 16 is inserted into the through hole 13h. A second bearing 19 is provided between the other end of the low-speed shaft 16 and the through hole 13h. The other end of the low-speed shaft 16 is rotatably supported on the bottom wall 13 a of the speed-up housing 13 via the second bearing 19. Therefore, the low-speed side shaft 16 is rotatably supported by the housing 11. The other end of the low-speed side shaft 16 projects from the motor chamber 12c through the through-hole 13h and into the gear box housing 13.

  A seal member 20 is provided between the other end of the low-speed shaft 16 and the through hole 13h. The seal member 20 is disposed closer to the motor chamber 12c than the second bearing 19 between the other end of the low-speed shaft 16 and the through hole 13h. The seal member 20 seals between the outer peripheral surface of the low-speed shaft 16 and the inner peripheral surface of the through hole 13h.

  The electric motor 17 includes a cylindrical stator 21 and a rotor 22 disposed inside the stator 21. The rotor 22 is fixed to the low-speed shaft 16 and rotates integrally with the low-speed shaft 16. Stator 21 surrounds rotor 22. The rotor 22 has a cylindrical rotor core 22a fixed to the low-speed side shaft 16, and a plurality of permanent magnets (not shown) provided on the rotor core 22a. The stator 21 has a cylindrical stator core 21a fixed to the inner peripheral surface of the peripheral wall 12b of the motor housing 12, and a coil 21b wound around the stator core 21a. When a current flows through the coil 21b, the rotor 22 and the low-speed side shaft 16 rotate integrally.

  The centrifugal compressor 10 includes a high-speed shaft 31 and a speed increasing device 30 that transmits the power of the low-speed shaft 16 to the high-speed shaft 31. Inside the housing 11, a gearbox 13c for accommodating the gearbox 30 is formed. The gearbox room 13 c is defined by the inner surface of the bottom wall 13 a of the gearbox housing 13, the inner circumferential surface of the peripheral wall 13 b, and the plate 14. Oil is stored in the gear box 13c. The seal member 20 suppresses the oil stored in the gear box 13c from leaking into the motor chamber 12c through the space between the outer peripheral surface of the low-speed shaft 16 and the inner peripheral surface of the through hole 13h. ing.

  The high-speed side shaft 31 is made of, for example, a metal material formed of iron or an alloy. The high-speed side shaft 31 is housed in the gear box 13 c with the axial direction of the high-speed side shaft 31 coinciding with the axial direction of the gear box housing 13. The end of the high-speed shaft 31 opposite to the motor housing 12 projects through the shaft insertion hole 14 h of the plate 14 into the compressor housing 15. The axis of the high-speed side shaft 31 matches the axis of the low-speed side shaft 16.

  The centrifugal compressor 10 includes an impeller 24 attached to the high-speed shaft 31. In the housing 11, an impeller chamber 15b for accommodating the impeller 24 is formed. The impeller chamber 15 b is partitioned by the compressor housing 15 and the plate 14. The plate 14 is a partition wall that partitions the impeller chamber 15b and the gearbox room 13c. The shaft insertion hole 14h through which the high-speed shaft 31 is inserted is formed in the plate 14 as a partition wall.

  A seal member 23 is provided between the outer peripheral surface of the high-speed side shaft 31 and the inner peripheral surface of the shaft insertion hole 14h. The seal member 23 is, for example, a mechanical seal. The seal member 23 seals between the outer peripheral surface of the high-speed shaft 31 and the inner peripheral surface of the shaft insertion hole 14h. Then, the oil stored in the gear box 13c may leak into the impeller chamber 15b through the space between the outer peripheral surface of the high-speed shaft 31 and the inner peripheral surface of the shaft insertion hole 14h by the seal member 23. Is suppressed.

  The impeller chamber 15b communicates with the suction port 15a. The impeller chamber 15b has a substantially truncated conical hole shape whose diameter gradually increases as the distance from the suction port 15a increases. The protruding end of the high-speed shaft 31 protruding into the compressor housing 15 protrudes into the impeller chamber 15b.

  The impeller 24 has a cylindrical shape whose diameter is gradually reduced from the rear surface 24a toward the distal end surface 24b. The impeller 24 extends in the rotation axis direction of the impeller 24, and has an insertion hole 24c through which the high-speed side shaft 31 can be inserted. The impeller 24 is attached to the high-speed shaft 31 so as to be rotatable integrally with the high-speed shaft 31 with a protruding end of the high-speed shaft 31 protruding into the compressor housing 15 being inserted into the insertion hole 24c. I have. Thus, the rotation of the high-speed side shaft 31 rotates the impeller 24 and compresses the air sucked from the suction port 15a. Therefore, the impeller 24 compresses air by rotating integrally with the high-speed side shaft 31.

  Further, the centrifugal compressor 10 includes a diffuser channel 25 into which the air compressed by the impeller 24 flows, and a discharge chamber 26 into which the air having passed through the diffuser channel 25 flows.

  The diffuser channel 25 is defined by a surface of the compressor housing 15 facing the plate 14 and the plate 14. The diffuser passage 25 is located radially outside the high-speed shaft 31 with respect to the impeller chamber 15b, and communicates with the impeller chamber 15b. The diffuser channel 25 is formed in an annular shape surrounding the impeller 24 and the impeller chamber 15b.

  The discharge chamber 26 is located radially outward of the high-speed side shaft 31 from the diffuser flow path 25 and communicates with the diffuser flow path 25. The discharge chamber 26 is annular. The impeller chamber 15b and the discharge chamber 26 communicate with each other via a diffuser flow path 25. The air compressed by the impeller 24 is further compressed by flowing through the diffuser channel 25, flows into the discharge chamber 26, and is discharged from the discharge chamber 26.

  The speed increaser 30 speeds up the rotation of the low speed side shaft 16 and transmits the rotation to the high speed side shaft 31. The speed increaser 30 is a so-called traction drive type (friction roller type). The speed increaser 30 includes a ring member 32 connected to the other end of the low speed side shaft 16. The ring member 32 is made of metal. The ring member 32 rotates with the rotation of the low-speed side shaft 16. The ring member 32 has a bottomed cylindrical shape having a disk-shaped base 33 connected to the other end of the low-speed side shaft 16 and a cylindrical portion 34 extending cylindrically from an outer edge of the base 33. . The base 33 extends in the radial direction of the low-speed side shaft 16 with respect to the low-speed side shaft 16. The axis of the cylindrical portion 34 matches the axis of the low-speed shaft 16.

  As shown in FIG. 2, a part of the high-speed side shaft 31 is disposed inside the cylindrical portion 34. Further, the speed increaser 30 includes three rollers 35 provided between the cylindrical portion 34 and the high-speed side shaft 31. The three rollers 35 are made of, for example, metal, and are made of the same metal as the high-speed side shaft 31, for example, iron or an alloy of iron. The three rollers 35 are arranged at predetermined intervals (for example, 120 degrees each) in the circumferential direction of the high-speed side shaft 31. The three rollers 35 have the same shape. The three rollers 35 are in contact with both the inner peripheral surface of the cylindrical portion 34 and the outer peripheral surface of the high-speed shaft 31.

  As shown in FIG. 1, each roller 35 has a cylindrical roller portion 35 a, a cylindrical first protrusion 35 c protruding from an axial first end surface 35 b of the roller portion 35 a, and an axial direction of the roller portion 35 a. And a cylindrical second protrusion 35e protruding from the second end face 35d. The axis of the roller portion 35a, the axis of the first projection 35c, and the axis of the second projection 35e coincide. The direction in which the axis of the roller portion 35a of each roller 35 extends (the direction of the rotation axis) matches the axis direction of the high-speed side shaft 31. The outer diameter of the roller portion 35a is larger than the outer diameter of the high-speed side shaft 31.

  As shown in FIGS. 1 and 2, the speed increaser 30 includes a support member 39 that rotatably supports each roller 35 in cooperation with the plate 14. The support member 39 is arranged inside the cylindrical portion 34. The support member 39 has a disc-shaped support base 40 and three pillar-shaped standing walls 41 erected from the support base 40. The support base 40 is disposed to face the plate 14 in the rotation axis direction of each roller 35. The three standing walls 41 extend from the surface 40 a of the support base 40 on the plate 14 side toward the plate 14. The three standing walls 41 are respectively arranged so as to fill three spaces defined by the inner peripheral surface of the cylindrical portion 34 and the outer peripheral surfaces of the two adjacent roller portions 35a.

  The support member 39 has three bolt insertion holes 45 through which the bolts 44 can be inserted. Each bolt insertion hole 45 penetrates each of the three standing walls 41 in the rotation axis direction of the roller 35. As shown in FIG. 1, a female screw hole 46 communicating with each bolt insertion hole 45 is formed on the surface 14 a of the plate 14 on the support member 39 side. The support member 39 is attached to the plate 14 by screwing each bolt 44 inserted into each bolt insertion hole 45 into each female screw hole 46.

  The surface 14a of the plate 14 on the support member 39 side has three concave portions 51 (only one concave portion 51 is shown in FIG. 1). The three recesses 51 are arranged at predetermined intervals (for example, 120 degrees each) in the circumferential direction of the high-speed side shaft 31. The arrangement positions of the three concave portions 51 correspond to the arrangement positions of the three rollers 35, respectively. An annular roller bearing 52 is arranged in each of the three concave portions 51.

  The surface 40a of the support base 40 on the plate 14 side has three concave portions 53 (only one concave portion 53 is shown in FIG. 1). The three concave portions 53 are arranged at predetermined intervals (for example, 120 degrees each) in the circumferential direction of the high-speed side shaft 31. The arrangement positions of the three concave portions 53 correspond to the arrangement positions of the three rollers 35, respectively. An annular roller bearing 54 is disposed in each of the three recesses 53.

  The first protrusion 35c of each roller 35 is inserted into a roller bearing 52 in each recess 51, and is rotatably supported by the plate 14 via the roller bearing 52. The second protrusion 35 e of each roller 35 is inserted into a roller bearing 54 in each recess 53, and is rotatably supported by the support member 39 via the roller bearing 54.

  The high-speed side shaft 31 is provided with a pair of flange portions 31f that are opposed to each other while being separated from each other in the axial direction of the high-speed side shaft 31. The roller portions 35a of the three rollers 35 are sandwiched between a pair of flange portions 31f. Thereby, the displacement between the high-speed side shaft 31 and the roller portions 35a of the three rollers 35 in the axial direction of the high-speed side shaft 31 is suppressed.

  As shown in FIG. 2, the three rollers 35, the ring member 32, and the high-speed shaft 31 are unitized in a state where the three rollers 35, the high-speed shaft 31, and the cylindrical portion 34 are pressed against each other. . The high speed shaft 31 is rotatably supported by three rollers 35.

  A pressing load is applied to the ring-side contact point Pa, which is the contact point between the outer peripheral surface of the roller portion 35a of the three rollers 35 and the inner peripheral surface of the cylindrical portion 34. Further, a pressing load is applied to a shaft-side contact point Pb, which is a contact point between the outer peripheral surfaces of the three rollers 35 and the outer peripheral surface of the high-speed shaft 31. The ring-side contact point Pa and the shaft-side contact point Pb extend in the axial direction of the high-speed side shaft 31.

  Then, when the electric motor 17 is driven and the low-speed side shaft 16 and the ring member 32 rotate, the rotational force of the ring member 32 is transmitted to the three rollers 35 via the respective ring-side contact points Pa, and the three The rollers 35 rotate, and the rotational forces of the three rollers 35 are transmitted to the high-speed side shaft 31 via the respective shaft-side contact points Pb. As a result, the high speed side shaft 31 rotates. At this time, the ring member 32 rotates at the same speed as the low-speed shaft 16, and the three rollers 35 rotate at a higher speed than the low-speed shaft 16. The high-speed shaft 31 having an outer diameter smaller than the outer diameter of the three rollers 35 rotates at a higher speed than the three rollers 35. Accordingly, the high-speed side shaft 31 rotates at a higher speed than the low-speed side shaft 16 by the speed increaser 30.

  As shown in FIG. 1, the centrifugal compressor 10 includes an oil pan 55 in which oil supplied to the gearbox 30 is stored. The oil pan 55 is formed inside the bottom wall 12a of the motor housing 12. The oil pan 55 is located at a position on the outer peripheral side of the bottom wall 12a of the motor housing 12.

  The centrifugal compressor 10 supplies an oil stored in the oil pan 55 to the gear box 13c, and an oil supply passage 56 provided in the oil supply passage 56 and sucks up and discharges the oil stored in the oil pan 55. An oil pump 57. The oil pump 57 is provided inside the bottom wall 12a of the motor housing 12. The oil pump 57 is, for example, a trochoid pump. The oil pump 57 is connected to one end of the low-speed shaft 16. The oil pump 57 is driven by the rotation of the low-speed shaft 16.

  The oil supply passage 56 has a first connection passage 56a connecting the oil pan 55 and the oil pump 57, and a second connection passage 56b connecting the oil pump 57 and the gearbox 13c. The first connection passage 56a is formed inside the motor housing 12. One end of the first connection passage 56a protrudes into the oil pan 55. The other end of the first connection passage 56a is connected to a suction port 57a of the oil pump 57. The second connection passage 56b passes through the motor housing 12 and the gearbox housing 13. One end of the second connection passage 56b is connected to a discharge port 57b of the oil pump 57. The other end of the second connection passage 56b is open to an upper portion in the direction of gravity in the speed increasing chamber 13c.

  The centrifugal compressor 10 includes an oil recirculation passage 58 that recirculates the oil in the gear box 13 c to the oil pan 55, and an oil cooler 59 that cools the oil flowing in the oil recirculation passage 58. The oil cooler 59 has a bottomed cylindrical cover member 59a attached to the outer peripheral surface of the peripheral wall 12b of the motor housing 12. A space 59b is defined by the inner surface of the cover member 59a and the outer peripheral surface of the peripheral wall 12b of the motor housing 12. The oil cooler 59 has a cooling pipe 59c disposed in the space 59b. Both ends of the cooling pipe 59c are supported by the motor housing 12. The cooling pipe 59c forms a part of the oil return passage 58.

  The cover member 59a is provided with an introduction pipe 59d and a discharge pipe 59e. A low-temperature fluid is introduced into the space 59b from the introduction pipe 59d. The low-temperature fluid introduced into the space 59b is discharged from the discharge pipe 59e, is cooled by a cooling device (not shown), and is again introduced into the space 59b through the introduction pipe 59d. The cryogenic fluid is, for example, water.

  The oil recirculation passage 58 has a third connection passage 58a that connects the gearbox 13c and the oil cooler 59, and a fourth connection passage 58b that connects the oil cooler 59 and the oil pan 55. The third connection passage 58 a penetrates through the gearbox housing 13 and extends to the inside of the peripheral wall 12 b of the motor housing 12. One end of the third connection passage 58a is open to a lower portion in the direction of gravity in the gear box 13c. The other end of the third connection passage 58a is connected to one end of the cooling pipe 59c. The fourth connection passage 58b is formed inside the motor housing 12. One end of the fourth connection passage 58b is connected to the other end of the cooling pipe 59c. The other end of the fourth connection passage 58b opens into the oil pan 55.

  When the electric motor 17 is driven, the oil pump 57 is driven by the rotation of the low-speed side shaft 16, and the oil stored in the oil pan 55 is discharged through the first connection passage 56 a and the suction port 57 a. And is discharged into the second connection passage 56b through the discharge port 57b. The oil pump 57 is driven such that the amount of oil discharged from the discharge port 57b increases proportionally as the rotation speed of the low-speed shaft 16 increases. Then, the oil discharged to the second connection passage 56b flows through the second connection passage 56b, flows out into the gear box 13c, and is supplied to, for example, the outer peripheral surface of the roller portion 35a. Thereby, the lubrication of the sliding portion between the roller portion 35a and the high-speed shaft 31 is improved.

  The oil that has contributed to the lubrication of the sliding portion between the roller portion 35a and the high-speed side shaft 31 is stored in the gear box 13c. The oil stored in the gear box 13c flows into the third connection passage 58a and passes through the third connection passage 58a, the cooling pipe 59c, and the fourth connection passage 58b. Here, the oil passing through the cooling pipe 59c is cooled by performing heat exchange with the low-temperature fluid introduced into the space 59b of the oil cooler 59. Then, the oil cooled by the oil cooler 59 is stored in the oil pan 55.

  The centrifugal compressor 10 includes a pressure release passage 60 that communicates the oil pan 55 with the outside. The pressure release passage 60 has a connection passage 60a, a buffer chamber 60b, and a discharge hole 60c. The buffer chamber 60b is formed inside the bottom wall 12a of the motor housing 12. The connection passage 60a is formed inside the bottom wall 12a of the motor housing 12. The connection passage 60a communicates the oil pan 55 with the buffer chamber 60b. One end of the connection passage 60a is open to an upper portion in the direction of gravity in the oil pan 55. The other end of the connection passage 60a opens to a lower portion in the direction of gravity in the buffer chamber 60b. The discharge hole 60c is formed in the bottom wall 12a of the motor housing 12. One end of the discharge hole 60c is open to an upper portion in the direction of gravity in the buffer chamber 60b. The other end of the discharge hole 60c opens to the outer surface of the bottom wall 12a of the motor housing 12 and communicates with the outside.

  The centrifugal compressor 10 has a bypass passage 61. The bypass passage 61 penetrates through the gearbox housing 13 and the motor housing 12. One end of the bypass passage 61 is open to an upper portion in the direction of gravity in the gear box 13c. The other end of the bypass passage 61 is open to an upper portion in the direction of gravity in the buffer chamber 60b. Accordingly, one end of the bypass passage 61 communicates with the gear box 13c, and the other end communicates with the outside via the buffer chamber 60b and the discharge hole 60c.

  As shown in FIG. 3, the centrifugal compressor 10 includes a communication passage 62 that connects the oil supply passage 56 and the bypass passage 61. The communication passage 62 is formed inside the motor housing 12. One end of the communication passage 62 communicates with the second connection passage 56b. The other end of the communication passage 62 communicates with the bypass passage 61. Therefore, the communication passage 62 has one end communicating with a portion of the oil supply passage 56 closer to the discharge side than the oil pump 57, and has the other end communicating with the bypass passage 61.

  The centrifugal compressor 10 includes a valve body 63 that opens and closes the bypass passage 61 and an urging spring 64 that urges the valve body 63. The valve body 63 slides inside the communication passage 62 so as to be able to protrude and retract from the bypass passage 61. Therefore, the valve body 63 is slidably disposed in the communication passage 62. The valve body 63 has a pressure receiving surface 63 a that receives a dynamic pressure of oil discharged from the oil pump 57 and flowing through the oil supply passage 56. Therefore, the pressure receiving surface 63a faces the second connection passage 56b of the oil supply passage 56.

  A spring housing recess 65 communicating with the bypass passage 61 is formed inside the motor housing 12. The spring receiving recess 65 is opposed to the communication passage 62 via the bypass passage 61. One end of the biasing spring 64 is supported on a surface 63b of the valve body 63 opposite to the pressure receiving surface 63a. The other end of the biasing spring 64 is supported by the bottom surface 65a of the spring receiving recess 65. The urging spring 64 urges the valve body 63 so as to press the valve body 63 toward the second connection passage 56b of the oil supply passage 56. Therefore, the urging spring 64 urges the valve body 63 toward the oil supply passage 56 so as to shut off the second connection passage 56b of the oil supply passage 56.

  When the pressure receiving surface 63a receives the dynamic pressure of the oil discharged from the oil pump 57 and flowing through the second connection passage 56b, the valve body 63 moves against the urging force of the urging spring 64 and moves from the communication passage 62 to the bypass passage. It moves in the direction projecting to 61. Then, the valve body 63 protruding from the communication passage 62 to the bypass passage 61 is in a valve closed state in which the second connection passage 56 b of the oil supply passage 56 is opened and the bypass passage 61 is shut off. Accordingly, when the pressure receiving surface 63a receives the dynamic pressure of the oil discharged from the oil pump 57 and flowing through the second connection passage 56b, the valve body 63 moves in the valve closing direction against the urging force of the urging spring 64. . Therefore, when the pressure receiving surface 63a receives the dynamic pressure of the oil discharged from the oil pump 57 and flowing through the second connection passage 56b, the urging spring 64 closes the valve body 63 against the urging force of the urging spring 64. The spring force is set to move in the valve direction.

  As shown in FIG. 4, when the pressure receiving surface 63a does not receive the dynamic pressure of the oil flowing through the second connection passage 56b, the valve body 63 is immersed in the communication passage 62 from the bypass passage 61 by the urging force of the urging spring 64. Move in the direction you want. Then, the valve body 63 immersed in the communication passage 62 from the bypass passage 61 is in an open state in which the second connection passage 56 b of the oil supply passage 56 is shut off and the bypass passage 61 is opened. Therefore, the biasing spring 64 is a biasing member that biases the valve body 63 toward the oil supply passage 56 so as to shut off the oil supply passage 56.

Next, the operation of the first embodiment will be described.
During operation of the centrifugal compressor 10, even if air leaks from the impeller chamber 15b to the gearbox 13c through the space between the outer peripheral surface of the high-speed side shaft 31 and the inner peripheral surface of the shaft insertion hole 14h. Since the air in the gear box 13c is discharged to the outside from the pressure release passage 60 via the oil recirculation passage 58 and the oil pan 55, a rise in the pressure in the gear box 13c is suppressed. Therefore, for example, when the impeller 24 is rotating at a low speed or when the operation of the centrifugal compressor 10 is stopped, the pressure in the impeller chamber 15b is lower than the pressure in the gear box 13c. , The difference between the pressure in the gear box 13c and the pressure in the impeller chamber 15b becomes smaller. Therefore, the oil in the gear box 13c is prevented from leaking into the impeller chamber 15b through the space between the outer peripheral surface of the high-speed shaft 31 and the inner peripheral surface of the shaft insertion hole 14h.

  For example, when the operation of the centrifugal compressor 10 is stopped, the driving of the oil pump 57 is stopped, and the pressure receiving surface 63a of the valve body 63 does not receive the dynamic pressure of the oil. Accordingly, the valve body 63 moves in a direction of blocking the second connection passage 56b of the oil supply passage 56 by the urging force of the urging spring 64, and increases the speed through the bypass passage 61, the buffer chamber 60b, and the discharge hole 60c. Communication between the machine room 13c and the outside is allowed.

  As shown in FIG. 3, during operation of the centrifugal compressor 10, the pressure receiving surface 63 a of the valve body 63 reduces the dynamic pressure of oil discharged from the oil pump 57 and flowing through the second connection passage 56 b of the oil supply passage 56. Upon receipt, the valve body 63 moves against the urging force of the urging spring 64 to open the second connection passage 56b of the oil supply passage 56 and shut off the bypass passage 61. Therefore, communication between the gear box 13c and the outside via the bypass passage 61 is cut off.

In the first embodiment, the following effects can be obtained.
(1-1) In the state where the operation of the centrifugal compressor 10 is stopped, the valve body 63 moves in the direction in which the oil supply passage 56 is shut off by the urging force of the urging spring 64, and the bypass passage 61 and the buffer chamber Communication between the gear box 13c and the outside via the discharge hole 60b and the discharge hole 60c is allowed. Therefore, even when the oil supply passage 56 and the oil recirculation passage 58 are filled with the oil while the operation of the centrifugal compressor 10 is stopped, the inside of the gear box 13c does not become a sealed space. . Here, there is a case where the temperature inside the gear box 13c rises and the air inside the gear box 13c expands. Even in this case, since the air in the gear box 13c is discharged to the outside through the bypass passage 61, the buffer chamber 60b, and the discharge hole 60c, the oil in the gear box 13c is pushed out by the air. To flow out to the oil recirculation passage 58 and to prevent the oil from flowing into the oil pan 55 via the oil recirculation passage 58. Therefore, the rise in the oil level of the oil pan 55 can be suppressed, so that the leakage of oil from the pressure release passage 60 to the outside due to the rise in the oil level of the oil pan 55 can be suppressed, and the oil supplied to the gearbox 30 can be suppressed. Can be prevented from decreasing.

  During operation of the centrifugal compressor 10, air leaks from the impeller chamber 15b to the gear box 13c through the space between the outer peripheral surface of the high-speed shaft 31 and the inner peripheral surface of the shaft insertion hole 14h. However, since the air in the gear box 13c is discharged to the outside from the pressure release passage 60 via the oil recirculation passage 58 and the oil pan 55, an increase in the pressure in the gear box 13c is suppressed. Further, during the operation of the centrifugal compressor 10, the valve body 63 receives the dynamic pressure of the oil discharged from the oil pump 57, and moves against the urging force of the urging spring 64 to move the oil supply passage 56. And the bypass passage 61 is shut off. Therefore, even if the oil in the gear box 13 c stirred by the gear box 30 during the operation of the centrifugal compressor 10 flows into the bypass passage 61, the oil leaks to the outside through the bypass passage 61. Can be suppressed. Therefore, even if the centrifugal compressor 10 is provided with the bypass passage 61, it is possible to suppress the amount of oil supplied to the speed increaser 30 from decreasing. From the above, it is possible to suppress a decrease in the amount of oil supplied to the gear box 30 while suppressing an increase in the pressure in the gear box 13c.

  (1-2) During operation of the centrifugal compressor 10, the valve body 63 is in a closed state in which the bypass passage 61 is shut off. It is possible to prevent the oil in the speed chamber 13c from flowing back to the oil pan 55 via the bypass passage 61, the buffer chamber 60b, and the connection passage 60a. Therefore, it is possible to prevent the high-temperature oil in the gear box 13 c from flowing into the oil pan 55 without being cooled by the oil cooler 59.

  (1-3) Oil is prevented from leaking from inside the gearbox room 13c into the impeller room 15b, so that supply of oil to the fuel cell together with air compressed by the centrifugal compressor 10 is suppressed. In addition, it is possible to prevent the power generation efficiency of the fuel cell from being reduced.

(Second embodiment)
Hereinafter, a second embodiment that embodies a centrifugal compressor will be described with reference to FIGS. In the embodiment described below, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

  As shown in FIG. 5, the centrifugal compressor 10 includes a communication passage 72 that communicates the impeller chamber 15b with the bypass passage 61. One end of the communication passage 72 communicates with a position facing the back surface 24a of the impeller 24 in the impeller chamber 15b, and the other end communicates with the bypass passage 61. The communication passage 72 penetrates through the plate 14 and has the other end located inside the gearbox housing 13.

  As shown in FIG. 6, the centrifugal compressor 10 includes a valve body 73 that opens and closes the bypass passage 61 and an urging spring 74 that urges the valve body 73. The valve body 73 slides in the communication passage 72 so as to be able to protrude and retract from the bypass passage 61. Therefore, the valve body 73 is slidably disposed in the communication passage 72.

  After being compressed by the impeller 24, the air that has flowed toward the back surface 24 a of the impeller 24 in the impeller chamber 15 b flows into the communication passage 72 and collides with the valve body 73. Therefore, the valve body 73 has a pressure receiving surface 73a that receives a back pressure that is a pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b. The back pressure, which is the pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b, is the pressure of the air that has been compressed by the impeller 24 and then wrapped around the back surface 24a side of the impeller 24 in the impeller chamber 15b.

  The biasing spring 74 is interposed between a portion of the plate 14 forming the communication passage 72 and the pressure receiving surface 73 a of the valve body 73. The urging spring 74 urges the valve body 73 toward the side opposite to the bypass passage 61. In the present embodiment, the biasing spring 74 is a tension spring, and pulls the valve body 73 toward the side opposite to the bypass passage 61. Therefore, the urging force of the urging spring 74 is the tensile force of the urging spring 74.

  When the pressure receiving surface 73a receives a back pressure which is a pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b, the valve body 73 projects from the communication passage 72 into the bypass passage 61 against the urging force of the urging spring 74. Move in the direction you want. The valve body 73 projecting from the communication passage 72 to the bypass passage 61 is in a closed state in which the bypass passage 61 is shut off. Therefore, when the pressure receiving surface 73a receives a back pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b, the valve body 73 moves against the urging force of the urging spring 74 to close the bypass passage 61. Move in the direction. Therefore, when the pressure receiving surface 73a receives the back pressure, which is the pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b, the urging spring 74 closes the valve body 73 against the urging force of the urging spring 74. The spring force is set to move in the direction.

  As shown in FIG. 7, when the pressure receiving surface 73a stops receiving the back pressure which is the pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b, the biasing force of the biasing spring 74 causes the bypass passage 61 to move. To the direction of immersion in the communication path 72 from the second direction. Then, the valve body 73 in a state of being immersed in the communication passage 72 from the bypass passage 61 is in an open state in which the bypass passage 61 is opened. Therefore, the biasing spring 74 is a biasing member that biases the valve body 73 toward the communication passage 72 so as to open the bypass passage 61.

Next, the operation of the second embodiment will be described.
For example, when the operation of the centrifugal compressor 10 is stopped, the rotation of the impeller 24 is stopped, and the pressure receiving surface 73a of the valve body 73 is a back pressure which is a pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b. Do not receive pressure. Accordingly, the valve body 73 moves in a direction to open the bypass passage 61 by the urging force of the urging spring 74, and the valve body 73 communicates with the outside of the gear box 13c via the bypass passage 61, the buffer chamber 60b, and the discharge hole 60c. Communication is allowed.

  As shown in FIG. 6, during operation of the centrifugal compressor 10, the pressure receiving surface 73 a of the valve body 73 receives a back pressure generated on the back surface 24 a side of the impeller 24 in the impeller chamber 15 b, so that the valve body 73 becomes It moves against the urging force of the urging spring 74 and shuts off the bypass passage 61. Therefore, communication between the gear box 13c and the outside via the bypass passage 61 is cut off.

In the second embodiment, the following effects can be obtained in addition to the effects (1-2) and (1-3) of the first embodiment.
(2-1) When the operation of the centrifugal compressor 10 is stopped, the valve body 73 does not receive the back pressure which is the pressure generated on the back surface 24a side of the impeller 24 in the impeller chamber 15b. For this reason, the valve body 73 moves in a direction to open the bypass passage 61 by the urging force of the urging spring 74, and the valve unit 73 communicates with the outside via the bypass passage 61, the buffer chamber 60b, and the gear box 13c via the discharge hole 60c. Communication is allowed. Therefore, even when the oil supply passage 56 and the oil recirculation passage 58 are filled with the oil while the operation of the centrifugal compressor 10 is stopped, the inside of the gear box 13c does not become a sealed space. . Here, there is a case where the temperature inside the gear box 13c rises and the air inside the gear box 13c expands. Even in this case, since the air in the gear box 13c is discharged to the outside through the bypass passage 61, the buffer chamber 60b, and the discharge hole 60c, the oil in the gear box 13c is pushed out by the air. To flow out to the oil recirculation passage 58 and to prevent the oil from flowing into the oil pan 55 via the oil recirculation passage 58. Therefore, the rise in the oil level of the oil pan 55 can be suppressed, so that the leakage of oil from the pressure release passage 60 to the outside due to the rise in the oil level of the oil pan 55 can be suppressed, and the oil supplied to the gearbox 30 can be suppressed. Can be prevented from decreasing.

  During operation of the centrifugal compressor 10, the valve body 73 receives a back pressure generated on the back side of the impeller chamber 15b, and moves against the urging force of the urging spring 74 to shut off the bypass passage 61. I do. Therefore, even if the oil in the gear box 13 c stirred by the gear box 30 during the operation of the centrifugal compressor 10 flows into the bypass passage 61, the oil leaks to the outside through the bypass passage 61. Can be suppressed. Therefore, even if the centrifugal compressor 10 is provided with the bypass passage 61, it is possible to suppress the amount of oil supplied to the speed increaser 30 from decreasing. From the above, it is possible to suppress a decrease in the amount of oil supplied to the gear box 30 while suppressing an increase in the pressure in the gear box 13c.

  Each of the above embodiments can be modified and implemented as follows. The above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

In the first embodiment, a tension spring that pulls the valve body 63 toward the second connection passage 56b of the oil supply passage 56 may be used as the biasing member.
In the second embodiment, an urging spring for urging the valve body 73 so as to press the valve body 73 toward the side opposite to the bypass passage 61 may be used as the urging member.

  In the above embodiments, the other end of the bypass passage 61 communicates with the outside via the buffer chamber 60b and the discharge hole 60c. However, the present invention is not limited to this, and the other end of the bypass passage 61 directly communicates with the outside. It may be.

In each of the above embodiments, the buffer chamber 60b constituting a part of the pressure release passage 60 may not be formed inside the motor housing 12.
In the above embodiments, for example, a pressure release valve that opens when the pressure in the gear box 13c reaches a predetermined pressure may be provided in the discharge hole 60c of the pressure release passage 60. The pressure relief valve may be an electromagnetic valve that opens and closes with an electric signal and opens only during the operation of the centrifugal compressor 10.

  In the above embodiments, the gas to be applied to the centrifugal compressor 10 and the gas to be compressed are arbitrary. For example, the centrifugal compressor 10 may be used in an air conditioner, and the gas to be compressed may be a refrigerant gas. In addition, the mounting target of the centrifugal compressor 10 is not limited to the vehicle, and is arbitrary.

  DESCRIPTION OF SYMBOLS 10 ... Centrifugal compressor, 11 ... Housing, 13c ... Speed increasing room, 14 ... Partition plate, 14h ... Shaft insertion hole, 15b ... Imperor room, 16 ... Low speed side shaft, 23 ... Seal member, 24 ... Impeller , 24a: rear surface, 30: speed increaser, 31: high-speed side shaft, 55: oil pan, 56: oil supply passage, 57: oil pump, 58: oil recirculation passage, 60: pressure release passage, 61: bypass passage, 62, 72 ... communication passage, 63, 73 ... valve element, 64, 74 ... urging spring which is an urging member.

Claims (2)

A low-speed shaft,
An impeller that rotates together with the high-speed side shaft to compress the gas,
A gearbox that transmits the power of the low-speed side shaft to the high-speed side shaft,
An impeller chamber accommodating the impeller, and a housing formed with a gearbox room containing the gearbox;
A partition wall that partitions the impeller room and the gearbox room;
A shaft insertion hole formed in the partition wall and through which the high-speed side shaft is inserted,
A seal member provided between an outer peripheral surface of the high-speed side shaft and an inner peripheral surface of the shaft insertion hole,
An oil pan in which oil supplied to the gearbox is stored,
An oil supply passage for supplying oil stored in the oil pan to the gearbox,
An oil recirculation passage for recirculating oil in the gearbox room to the oil pan,
A centrifugal compressor comprising: a pressure release passage communicating the oil pan with the outside;
A bypass passage having one end communicating with the gear box and the other end communicating with the outside;
An oil pump provided in the oil supply passage and for sucking up and discharging oil stored in the oil pan,
A communication passage having one end communicating with a portion of the oil supply passage closer to the discharge side than the oil pump, and the other end communicating with the bypass passage;
A valve body slidably disposed in the communication passage;
An urging member for urging the valve body toward the oil supply passage so as to shut off the oil supply passage,
When receiving the dynamic pressure of the oil discharged from the oil pump, the valve body moves against the urging force of the urging member to open the oil supply passage and shut off the bypass passage. Characteristic centrifugal compressor. A low-speed shaft,
An impeller that rotates together with the high-speed side shaft to compress the gas,
A gearbox that transmits the power of the low-speed side shaft to the high-speed side shaft,
An impeller chamber accommodating the impeller, and a housing formed with a gearbox room containing the gearbox;
A partition wall that partitions the impeller room and the gearbox room;
A shaft insertion hole formed in the partition wall and through which the high-speed side shaft is inserted,
A seal member provided between an outer peripheral surface of the high-speed side shaft and an inner peripheral surface of the shaft insertion hole,
An oil pan in which oil supplied to the gearbox is stored,
An oil supply passage for supplying oil stored in the oil pan to the gearbox,
An oil recirculation passage for recirculating oil in the gearbox room to the oil pan,
A centrifugal compressor comprising: a pressure release passage communicating the oil pan with the outside;
A bypass passage having one end communicating with the gear box and the other end communicating with the outside;
A communication passage having one end communicating with a position facing the back surface of the impeller in the impeller chamber, and the other end communicating with the bypass passage;
A valve body slidably disposed in the communication passage;
An urging member for urging the valve body toward the communication passage so as to open the bypass passage,
The centrifugal compressor, wherein the valve element receives a back pressure generated on the back side of the impeller and moves against the urging force of the urging member to shut off the bypass passage.