JP2019173953A - Centrifugal compressor - Google Patents

Abstract

To suppress the leakage of oil in a speed increaser chamber into an impeller chamber.SOLUTION: A negative pressure generation groove 95 has an overlapping groove 96 which is overlapped on a negative pressure flat face 92b in a radial direction of a high-speed side shaft 31. By this constitution, oil passing between a rotation-side slide movement face and the negative pressure flat face 92b, and trying to flow into a seal face 92s is sucked by the overlapping groove 96. Therefore, it is avoided that the oil flows into the seal face 92s by passing between the rotation-side slide movement face and the negative pressure flat face 92b, and the oil in a speed increaser chamber leaks out into an impeller chamber via a clearance between the rotation-side slide movement face and the seal face 92s.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a centrifugal compressor.

  The centrifugal compressor includes a low speed side shaft, an impeller attached to the high speed side shaft, and a speed increaser that transmits the power of the low speed side shaft to the high speed side shaft. An impeller chamber for accommodating the impeller and a speed increaser chamber for accommodating the speed increaser are formed in the housing of the centrifugal compressor. The impeller chamber and the gear box are separated by a partition wall. A shaft insertion hole is formed in the partition wall. The high speed side shaft protrudes from the gearbox interior through the shaft insertion hole and into the impeller chamber.

  In such a centrifugal compressor, oil is supplied to the speed increaser in order to suppress friction and seizure of a sliding portion between the high speed side shaft and the speed increaser. Since the oil supplied to the speed increaser is stored in the speed increaser room, the oil stored in the speed increaser room is prevented from leaking into the impeller room through the shaft insertion hole. For example, a mechanical seal is provided in the insertion hole.

  In general, the mechanical seal is disposed in a shaft insertion hole in a state where the rotary seal that rotates integrally with the high-speed side shaft is opposed to the rotary ring in the axial direction of the high-speed side shaft and surrounds the high-speed side shaft. And a fixed ring. The end surface on the stationary ring side of the rotating ring has a flat rotating surface sliding surface that slides with the stationary ring. The end surface on the rotating ring side of the stationary ring has a flat fixed-side sliding surface that slides with the rotating side sliding surface of the rotating ring. Furthermore, the fixed side sliding surface has a sealing surface with the rotation side sliding surface.

  As shown in FIG. 8, for example, in the mechanical seal 100 of Patent Document 1, a positive pressure generating groove 103 (Rayleigh step mechanism) and a negative pressure generating groove 104 (reverse Rayleigh step mechanism) are formed on the fixed side sliding surface 102 of the fixed ring 101. ) And a communication groove 105 (radial groove). The positive pressure generating groove 103, the negative pressure generating groove 104, and the communication groove 105 are located on the radially outer side of the high speed side shaft with respect to the seal surface 102 s of the fixed side sliding surface 102. The communication groove 105 communicates with the positive pressure generation groove 103 and the negative pressure generation groove 104 and also communicates with the outer peripheral side of the stationary ring 101. The positive pressure generating groove 103 is located on the outer side in the radial direction of the high speed side shaft than the negative pressure generating groove 104. The positive pressure generating groove 103 extends from the communication groove 105 in the rotation direction of the rotating ring (the direction indicated by the arrow R100 in FIG. 8). The negative pressure generating groove 104 extends from the communication groove 105 in a direction opposite to the rotation direction of the rotary ring.

  The positive pressure generating groove 103 has a positive pressure step surface 103a (Rayleigh step) at the end of the positive pressure generating groove 103 opposite to the communication groove 105. The stationary-side sliding surface 102 has a positive pressure flat surface 102a that is continuous with the positive pressure step surface 103a in the rotation direction of the rotary ring. Further, the negative pressure generating groove 104 has a negative pressure step surface 104a (reverse Rayleigh step) at the end of the negative pressure generating groove 104 on the side opposite to the communication groove 105. The stationary-side sliding surface 102 has a negative pressure flat surface 102b that is continuous with the negative pressure step surface 104a in the direction opposite to the rotation direction of the rotary ring.

  When the rotating ring rotates with the rotation of the high speed side shaft, the oil interposed between the rotating ring and the fixed ring 101 moves following the rotation of the rotating ring. At this time, the oil supplied into the positive pressure generating groove 103 via the communication groove 105 moves toward the positive pressure step surface 103a following the rotation of the rotary ring, and gets over the positive pressure step surface 103a. It tries to move toward the positive pressure flat surface 102a. As a result, a positive pressure is generated between the rotating side sliding surface and the fixed side sliding surface 102, and the interval between the rotating side sliding surface and the fixed side sliding surface 102 is widened to fix the rotating side sliding surface and the fixed side sliding surface. An oil film is formed by oil between the side sliding surface 102 and the slidability between the rotating side sliding surface and the sealing surface 102s of the fixed side sliding surface 102 is improved.

  Further, when the rotating ring rotates with the rotation of the high-speed side shaft, the oil interposed between the rotating side sliding surface and the negative pressure flat surface 102b of the fixed side sliding surface 102 follows the rotation of the rotating ring. It moves and flows into the negative pressure generating groove 104 through the negative pressure step surface 104a. As a result, the negative pressure generating groove 104 has a negative pressure, and oil that tends to leak from the gearbox into the impeller chamber through the shaft insertion hole is easily sucked into the negative pressure generating groove 104. Then, the oil sucked into the negative pressure generating groove 104 follows the rotation of the rotating ring and flows toward the communication groove 105, and is more than the outer peripheral surface of the fixed ring 101 in the shaft insertion hole via the communication groove 105. Discharged radially outside the high speed shaft. As a result, the oil stored in the gearbox chamber is prevented from leaking into the impeller chamber through the space between the rotation-side sliding surface and the sealing surface 102s of the fixed-side sliding surface 102.

International Publication No. 2014/148316

  However, when the mechanical seal 100 as in Patent Document 1 is used, the oil flows between the rotation side sliding surface and the negative pressure flat surface 102b and flows toward the seal surface 102s. There is a possibility that oil leaks into the impeller chamber through the space between the rotation-side sliding surface and the seal surface 102s.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a centrifugal compressor that can prevent oil in the gearbox from leaking into the impeller chamber. It is in.

  A centrifugal compressor that solves the above problems includes a low-speed side shaft, an impeller attached to the high-speed side shaft, a speed increaser that transmits power of the low-speed side shaft to the high-speed side shaft, and an impeller that houses the impeller. And a housing in which a speed increaser chamber that houses the speed increaser is formed, a partition wall that partitions the impeller chamber and the speed increaser chamber, and a high speed side shaft that is formed in the partition wall and A shaft insertion hole to be inserted; an oil supply passage for supplying oil to the speed increaser; and a mechanical seal provided in the shaft insertion hole. The mechanical seal rotates integrally with the high-speed side shaft. A rotating ring that is disposed opposite to the rotating ring in the axial direction of the high speed side shaft and surrounds the high speed side shaft. A stationary ring fixed to the through hole, and an end surface on the stationary ring side of the rotating ring has a flat rotational surface sliding surface that slides on the stationary ring, and The end surface on the rotating ring side has a flat fixed-side sliding surface that slides with the rotating-side sliding surface, and the fixed-side sliding surface is a sealing surface with the rotating-side sliding surface. The fixed-side sliding surface has a positive pressure generating groove, a negative pressure generating groove, a first communication groove communicating with the positive pressure generating groove, and a second communication groove communicating with the negative pressure generating groove. The positive pressure generating groove, the negative pressure generating groove, the first communication groove, and the second communication groove are formed on the outer side in the radial direction of the high-speed shaft than the seal surface, and the first communication groove The groove and the second communication groove communicate with the outer peripheral side of the stationary ring, and the positive pressure generating groove rotates from the first communication groove to the rotating ring. The positive pressure generating groove has a positive pressure step surface at an end opposite to the first communication groove, and the negative pressure generating groove extends from the second communication groove to the rotating ring. The negative pressure generating groove has a negative pressure step surface extending in a direction opposite to the rotation direction and opposite to the second communication groove, and the fixed-side sliding surface has the positive pressure step. A positive pressure flat surface that continues in the rotation direction of the rotary ring with respect to a surface, and a negative pressure flat surface that continues in a direction opposite to the rotation direction of the rotary ring with respect to the negative pressure step surface. The negative pressure generating groove has an overlap groove that overlaps the negative pressure flat surface in the radial direction of the high speed side shaft.

  According to this, the oil which passes between the rotation side sliding surface and the negative pressure flat surface and tries to flow toward the sealing surface can be sucked by the overlap groove. Therefore, the oil passes between the rotating side sliding surface and the negative pressure flat surface and flows toward the sealing surface, and the oil in the speed increasing gear chamber passes through between the rotating side sliding surface and the sealing surface. Leakage into the impeller chamber can be suppressed.

  In the centrifugal compressor, the overlap groove, the negative pressure generating groove, and the position of the connection position with the second communication groove and the position of the negative pressure step surface are offset in the radial direction of the high speed side shaft. Furthermore, it is good to form by extending over 360 degree | times toward the direction opposite to the rotation direction of the said rotating ring from the said 2nd communicating groove. According to this, the negative pressure generating groove having the overlap groove can be easily formed.

  According to this invention, it is possible to prevent oil in the gearbox from leaking into the impeller chamber.

The side sectional view showing the centrifugal compressor in an embodiment. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. The sectional side view which expands and shows a mechanical seal periphery. The front view of a fixed ring. (A) is a figure which shows typically the relationship of a positive pressure generating groove, a communicating groove, a positive pressure flat surface, and a rotating ring, (b) is a negative pressure generating groove, a communicating groove, a negative pressure flat surface, and a rotating ring. The figure which shows a relationship typically. The front view of the stationary ring in another embodiment. The front view of the stationary ring in another embodiment. The front view of the fixed ring in a prior art example.

  Hereinafter, an embodiment embodying 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, the housing 11 of the centrifugal compressor 10 includes a motor housing 12, a speed increaser housing 13 connected to the motor housing 12, a plate 14 connected to the speed increaser housing 13, and a plate 14. And a compressor housing 15 connected to the compressor housing 15. The motor housing 12, the speed increaser housing 13, the plate 14, and the compressor housing 15 are made of, for example, a metal material made of aluminum. The housing 11 is substantially cylindrical. The motor housing 12, the speed increaser 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 is a bottomed cylindrical shape having a disk-shaped bottom wall 12a and a peripheral wall 12b extending in a cylindrical shape from the outer peripheral edge of the bottom wall 12a. The speed-up gear housing 13 is a bottomed cylindrical shape which has a disk-shaped bottom wall 13a and a peripheral wall 13b extending in a cylindrical shape from the outer peripheral edge of the bottom wall 13a.

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

  The end of the peripheral wall 13 b of the speed increaser housing 13 opposite to the bottom wall 13 a is connected to the plate 14. The opening on the opposite side of the peripheral wall 13 b of the speed increaser housing 13 from the bottom wall 13 a is closed by the plate 14. A shaft insertion hole 14 h is formed at the center of the plate 14.

  The compressor housing 15 is connected to the surface of the plate 14 opposite to the speed increaser housing 13. The compressor housing 15 is formed with a suction port 15a through which air, which is a gas, is sucked. The suction port 15 a opens in the center of the end surface 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 surface 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 that rotates the low speed side shaft 16. A motor chamber 12 c that houses the electric motor 17 is formed in the housing 11. The motor chamber 12 c is defined by the inner surface of the bottom wall 12 a of the motor housing 12, the inner peripheral surface of the peripheral wall 12 b, and the outer surface of the bottom wall 13 a of the speed increaser 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 coincides with 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 portion 12 f projects from the inner surface of the bottom wall 12 a of the motor housing 12. One end portion of the low speed side shaft 16 is inserted into the boss portion 12f. A first bearing 18 is provided between one end of the low speed side shaft 16 and the boss 12f. One end portion of the low speed side shaft 16 is rotatably supported by the bottom wall 12 a of the motor housing 12 via the first bearing 18.

  The other end of the low speed side shaft 16 is inserted into the through hole 13h. A second bearing 19 is provided between the other end of the low speed side shaft 16 and the through hole 13h. The other end of the low speed side shaft 16 is rotatably supported by the bottom wall 13 a of the speed increaser 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 shaft 16 projects from the motor chamber 12c through the through hole 13h and protrudes into the gearbox housing 13.

  A seal member 20 is provided between the other end of the low speed side 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 side shaft 16 and the through hole 13h. The seal member 20 seals between the outer peripheral surface of the low speed side 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 side shaft 16 and rotates integrally with the low speed side shaft 16. The stator 21 surrounds the rotor 22. The rotor 22 includes 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. Then, the current flows through the coil 21b, whereby the rotor 22 and the low speed side shaft 16 rotate integrally.

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

  The high speed side shaft 31 is made of a metal material formed of, for example, iron or an alloy. The high speed side shaft 31 is accommodated in the speed increaser chamber 13 c in a state in which the axial direction of the high speed side shaft 31 coincides with the axial direction of the speed increaser housing 13. The end of the high speed side shaft 31 opposite to the motor housing 12 passes through the shaft insertion hole 14 h of the plate 14 and protrudes into the compressor housing 15. The axis of the high speed side shaft 31 coincides with the axis of the low speed side shaft 16.

  The centrifugal compressor 10 includes an impeller 24 attached to the high speed side shaft 31. An impeller chamber 15 b that houses the impeller 24 is formed in the housing 11. 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 speed increaser chamber 13c. A shaft insertion hole 14h through which the high-speed shaft 31 is inserted is formed in the plate 14 that is a partition wall.

  The centrifugal compressor 10 includes a mechanical seal 71 provided in the shaft insertion hole 14h. The mechanical seal 71 prevents oil stored in the speed increaser chamber 13c from leaking into the impeller chamber 15b through the shaft insertion hole 14h.

  The impeller chamber 15b and the suction port 15a communicate with each other. The impeller chamber 15b has a substantially truncated cone hole shape that gradually increases in diameter as it moves away from the suction port 15a. A protruding end portion of the high speed side shaft 31 protruding into the compressor housing 15 protrudes into the impeller chamber 15b.

  The impeller 24 has a cylindrical shape with a diameter gradually reduced from the base end surface 24a toward the front end surface 24b. The impeller 24 has an insertion hole 24c that extends in the rotation axis direction of the impeller 24 and through which the high-speed shaft 31 can be inserted. The impeller 24 is attached to the high speed side shaft 31 so as to be rotatable integrally with the high speed side shaft 31 in a state where the protruding end portion of the high speed side shaft 31 protruding into the compressor housing 15 is inserted into the insertion hole 24c. Yes. Thereby, the impeller 24 is rotated by the rotation of the high-speed side shaft 31, and the air sucked from the suction port 15a is compressed. Therefore, the impeller 24 rotates integrally with the high speed side shaft 31 and compresses air.

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

  The diffuser flow path 25 is defined by the plate 14 and the surface of the compressor housing 15 that faces the plate 14. The diffuser flow path 25 is located on the radially outer side of the high speed side shaft 31 with respect to the impeller chamber 15b and communicates with the impeller chamber 15b. The diffuser flow path 25 is formed in an annular shape surrounding the impeller 24 and the impeller chamber 15b.

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

  The speed increaser 30 increases the rotation of the low speed side shaft 16 and transmits it 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 is 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 in a cylindrical shape from the outer edge portion 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 coincides with the axis of the low speed side shaft 16.

  As shown in FIG. 2, a part of the high speed side shaft 31 is disposed inside the cylindrical portion 34. 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 metal, for example, and are made of the same metal as the high-speed side shaft 31, for example, iron or an iron alloy. 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 side shaft 31.

  As shown in FIG. 1, each roller 35 includes a cylindrical roller portion 35a, a cylindrical first protrusion 35c protruding from an axial first end surface 35b of the roller portion 35a, and an axial direction of the roller portion 35a. And a cylindrical second protrusion 35e protruding from the second end face 35d. The axial center of the roller portion 35a, the axial center of the first protrusion 35c, and the axial center of the second protrusion 35e coincide. The direction in which the axial center of the roller portion 35a of each roller 35 extends (rotational axis direction) coincides with the axial direction of the high-speed side shaft 31. The outer diameter of the roller portion 35 a 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 disposed inside the cylindrical portion 34. The support member 39 includes a disk-shaped support base 40 and three columnar standing walls 41 erected from the support base 40. The support base 40 is disposed to face the plate 14 in the direction of the rotation axis of each roller 35. The three standing walls 41 extend from the surface 40a on the plate 14 side of the support base 40 toward the plate 14, respectively. The three standing walls 41 are respectively disposed 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.

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

  The surface 14a on the support member 39 side of the plate 14 has three recesses 51 (only one recess 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 disposed in each of the three recesses 51.

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

  The first protrusions 35 c of the respective rollers 35 are inserted into roller bearings 52 in the respective recesses 51 and are rotatably supported by the plate 14 via the roller bearings 52. The second protrusion 35 e of each roller 35 is inserted into the 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 disposed to face each other while being spaced apart 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 position shift of the high speed side shaft 31 and the roller part 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 side shaft 31 are unitized with the three rollers 35, the high speed side shaft 31, and the cylindrical portion 34 pressed against each other. . The high speed side shaft 31 is rotatably supported by three rollers 35.

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

  When the electric motor 17 is driven and the low-speed 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 ring-side contact points Pa, and The roller 35 rotates, and the rotational force of the three rollers 35 is transmitted to the high speed side shaft 31 via each shaft side contact portion 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 side shaft 16, and the three rollers 35 rotate at a higher speed than the low speed side shaft 16. The high speed side shaft 31 having an outer diameter smaller than the outer diameters of the three rollers 35 rotates at a higher speed than the three rollers 35. Thereby, the high speed side shaft 31 is rotated 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 supply passage 60 that supplies oil to the speed increaser 30. The oil supply passage 60 also supplies oil to the mechanical seal 71. Further, the centrifugal compressor 10 sucks up the oil stored in the oil pan 56, the oil cooler 55 that cools the oil flowing through the oil supply passage 60, the oil pan 56 that stores the oil flowing through the oil supply passage 60, and the oil pan 56. An oil pump 57 for discharging.

  The oil cooler 55 has a bottomed cylindrical cover member 55 a attached to the outer peripheral surface of the peripheral wall 12 b of the motor housing 12. A space 55 b is defined by the inner surface of the cover member 55 a and the outer peripheral surface of the peripheral wall 12 b of the motor housing 12. The oil cooler 55 has a cooling pipe 55c disposed in the space 55b. Both ends of the cooling pipe 55 c are supported by the motor housing 12. The cooling pipe 55 c forms a part of the oil supply passage 60.

  The cover member 55a is provided with an introduction pipe 55d and a discharge pipe 55e. A low temperature fluid is introduced into the space 55b from the introduction pipe 55d. The low-temperature fluid introduced into the space 55b is discharged from the discharge pipe 55e, cooled by a cooling device (not shown), and then again introduced into the space 55b through the introduction pipe 55d. The cryogenic fluid is, for example, water.

  The oil pan 56 is formed inside the bottom wall 12 a of the motor housing 12. The oil pan 56 is located on the outer peripheral side portion of the bottom wall 12 a of the motor housing 12. The oil pump 57 is provided inside the bottom wall 12 a of the motor housing 12. The oil pump 57 is a trochoid pump, for example. The oil pump 57 is connected to one end of the low speed side shaft 16. The oil pump 57 is driven as the low-speed shaft 16 rotates.

  The oil supply passage 60 has a first connection passage 61 that connects the gearbox 13 c and the oil cooler 55. The first connection passage 61 extends through the gearbox housing 13 to the inside of the peripheral wall 12b of the motor housing 12. One end of the first connection passage 61 opens into the speed increaser chamber 13c. The other end of the first connection passage 61 is connected to one end of the cooling pipe 55c.

  The centrifugal compressor 10 is mounted on the fuel cell vehicle such that a portion of the first connection passage 61 that opens into the speed increaser chamber 13c is located on the lower side in the gravity direction. Therefore, the oil in the speed increaser chamber 13 c flows into the first connection passage 61.

  The oil supply passage 60 has a second connection passage 62 that connects the oil cooler 55 and the oil pan 56. The second connection passage 62 is formed inside the motor housing 12. One end of the second connection passage 62 is connected to the other end of the cooling pipe 55c. The other end of the second connection passage 62 opens into the oil pan 56.

  The oil stored in the speed increaser chamber 13 c flows into the first connection passage 61 and passes through the first connection passage 61, the cooling pipe 55 c, and the second connection passage 62. Here, the oil passing through the cooling pipe 55c is cooled by heat exchange with the low-temperature fluid introduced into the space 55b of the oil cooler 55. Then, the oil cooled by the oil cooler 55 is stored in the oil pan 56.

  The oil supply passage 60 has a third connection passage 63 that connects the oil pan 56 and the oil pump 57. The third connection passage 63 is formed inside the motor housing 12. One end of the third connection passage 63 protrudes into the oil pan 56. The other end of the third connection passage 63 is connected to the suction port 57 a of the oil pump 57.

  The oil supply passage 60 has a fourth connection passage 64 connected to the discharge port 57 b of the oil pump 57. The fourth connection passage 64 extends through the bottom wall 12 a and the peripheral wall 12 b of the motor housing 12 to the inside of the peripheral wall 13 b of the speed increaser housing 13. One end of the fourth connection passage 64 is connected to the discharge port 57 b of the oil pump 57. The other end of the fourth connection passage 64 is located inside the peripheral wall 13 b of the speed increaser housing 13.

  The oil supply passage 60 includes a first branch passage 65 and a second branch passage 66 that branch from the other end of the fourth connection passage 64. The first branch passage 65 extends from the other end of the fourth connection passage 64 toward the motor housing 12 and penetrates the peripheral wall 13 b of the speed increaser housing 13 and the bottom wall 13 a of the speed increaser housing 13. One end of the first branch passage 65 communicates with the other end of the fourth connection passage 64. The other end of the first branch passage 65 opens into the through hole 13h.

  The second branch passage 66 extends from the other end of the fourth connection passage 64 toward the plate 14 and extends through the peripheral wall 13 b of the speed increaser housing 13 to the inside of the plate 14. One end of the second branch passage 66 communicates with the other end of the fourth connection passage 64. The other end of the second branch passage 66 is located inside the plate 14.

  The oil supply passage 60 has a common passage 67 that communicates with the other end of the second branch passage 66. The common passage 67 extends in a straight line from the other end of the second branch passage 66 in the direction perpendicular to the second branch passage 66 and downward in the direction of gravity. The oil supply passage 60 includes a seal member side supply passage 69 and a speed increasing device side supply passage 70 that branch from the common passage 67. One end of the seal member side supply passage 69 communicates with the common passage 67. The other end of the seal member side supply passage 69 is open to the shaft insertion hole 14h. The speed-increasing side supply passage 70 extends linearly from the common passage 67 toward the side opposite to the compressor housing 15, passes through the plate 14, passes through the standing wall 41, and the roller portion 35 a in the standing wall 41. It is opened at a position facing the outer peripheral surface of. Therefore, the speed increaser side supply passage 70 communicates with the speed increaser chamber 13c.

  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 56 is passed through the third connection passage 63 and the suction port 57a. It is sucked in and discharged into the fourth connection passage 64 through the discharge port 57b. The oil pump 57 is driven so that the amount of oil discharged from the discharge port 57b increases proportionally as the rotational speed of the low-speed shaft 16 increases. The oil discharged to the fourth connection passage 64 flows through the fourth connection passage 64 and is distributed to the first branch passage 65 and the second branch passage 66, respectively.

  The oil distributed from the fourth connection passage 64 to the first branch passage 65 flows through the first branch passage 65 and flows into the through hole 13 h and is supplied to the seal member 20 and the second bearing 19. As a result, the sliding portion between the seal member 20 and the low speed side shaft 16 and the sliding portion between the second bearing 19 and the low speed side shaft 16 are excellently lubricated.

  The oil distributed from the fourth connection passage 64 to the second branch passage 66 flows into the common passage 67 through the second branch passage 66. Part of the oil flowing through the common passage 67 is distributed to the seal member side supply passage 69, and other oil flows through the speed increaser side supply passage 70. The oil distributed from the common passage 67 to the seal member side supply passage 69 flows through the seal member side supply passage 69, flows into the shaft insertion hole 14 h, and is supplied to the mechanical seal 71. Further, the oil flowing through the speed increaser side supply passage 70 is supplied to the outer peripheral surface of the roller portion 35a. Thereby, the lubrication of the sliding part of the roller part 35a and the high speed side shaft 31 becomes favorable. The oil supplied to the outer peripheral surfaces of the mechanical seal 71 and the roller portion 35a is returned to the speed increaser chamber 13c.

  As shown in FIG. 3, the shaft insertion hole 14h includes a large-diameter hole 141h, a small-diameter hole 142h communicating with the large-diameter hole 141h, an annular step surface 143h connecting the large-diameter hole 141h and the small-diameter hole 142h, have. The large diameter hole 141h communicates with the impeller chamber 15b. The small diameter hole 142h communicates with the gearbox 13c. The step surface 143 h extends in the radial direction of the high speed side shaft 31. The large-diameter hole 141 h and the small-diameter hole 142 h are circular holes, and the respective axis centers coincide with the rotation axis of the high-speed side shaft 31.

  One of the pair of flange portions 31f is disposed in the small diameter hole 142h. The high-speed side shaft 31 passes through the small-diameter hole 142h and the large-diameter hole 141h from the speed increaser chamber 13c and protrudes into the impeller chamber 15b.

  The mechanical seal 71 includes a rotating ring 81 that rotates integrally with the high-speed shaft 31 and a stationary ring 91 that is fixed to the shaft insertion hole 14h. In the present embodiment, the flange portion 31 f disposed in the small diameter hole 142 h functions as the rotating ring 81. Therefore, in the present embodiment, the rotary ring 81 is integrally formed with the high speed side shaft 31. The rotating ring 81 has an annular shape. The fixed ring 91 is disposed to face the rotating ring 81 in the axial direction of the high speed side shaft 31 and is fixed to the large diameter hole 141 h so as to surround the high speed side shaft 31. Therefore, the stationary ring 91 is disposed closer to the impeller chamber 15 b than the rotating ring 81.

  The mechanical seal 71 includes a spring 72 that presses the fixed ring 91 toward the rotating ring 81, a spring holding portion 73 that holds the spring 72, and the fixed ring 91 that covers the fixed ring 91 together with the spring 72 and the spring holding portion 73. And a cartridge 74 for holding 91.

  The cartridge 74 rises toward the rotary ring 81 from the outer peripheral edge of the bottom wall 74a, the cylindrical inner peripheral wall 74b rising from the inner peripheral edge of the bottom wall 74a toward the rotary ring 81, and the outer peripheral edge of the bottom wall 74a. And a cylindrical outer peripheral wall 74c. The outer peripheral wall 74c extends along the inner peripheral surface of the large-diameter hole 141h. The cartridge 74 is fixed to the shaft insertion hole 14h by fitting the outer peripheral wall 74c to the inner peripheral surface of the large diameter hole 141h. The high speed side shaft 31 passes through the inside of the inner peripheral wall 74b and the inside of the bottom wall 74a.

  The stationary ring 91, the spring 72, and the spring holding portion 73 are disposed in a space defined by the bottom wall 74a, the outer peripheral surface of the inner peripheral wall 74b, and the inner peripheral surface of the outer peripheral wall 74c. The cartridge 74 holds the fixed ring 91 so as not to rotate integrally with the high speed side shaft 31 while being movable in the axial direction of the high speed side shaft 31. For this reason, the fixed ring 91 is allowed to move in the axial direction of the high speed side shaft 31, while the movement of the high speed side shaft 31 in the circumferential direction is restricted.

  The spring 72 and the spring holding portion 73 are disposed between the bottom wall 74 a of the cartridge 74 and the fixed ring 91. The spring holding portion 73 is in contact with the fixed ring 91, and the spring 72 connects the spring holding portion 73 and the bottom wall 74a. Thereby, the urging force of the spring 72 is transmitted to the stationary ring 91 via the spring holding portion 73, and the stationary ring 91 is pressed toward the rotating ring 81.

  The end surface 81 a on the stationary ring 91 side of the rotating ring 81 has a flat rotating surface-side sliding surface 82 that slides with the stationary ring 91. An end surface 91 a on the rotating ring 81 side of the fixed ring 91 has a flat fixed surface sliding surface 92 that slides with the rotating side sliding surface 82. The fixed-side sliding surface 92 has a seal surface 92 s with the rotation-side sliding surface 82.

  Further, a part of the inner peripheral surface of the fixed ring 91 is recessed outward in the radial direction of the high speed side shaft 31. A part of the inner peripheral wall 74 b is recessed inward in the radial direction of the high-speed side shaft 31. An annular seal is formed between a portion of the inner peripheral surface of the fixed ring 91 that is recessed outward in the radial direction of the high speed side shaft 31 and a portion of the inner peripheral wall 74b that is recessed inward in the radial direction of the high speed side shaft 31. A member 75 is provided.

  An annular notch recess 91 b is formed on the outer periphery of the end surface 91 a of the fixed ring 91. The notch recess 91 b is in contact with the step surface 143 h in the axial direction of the high speed side shaft 31. The other end of the seal member side supply passage 69 opens to the inner peripheral surface of the small diameter hole 142h and the step surface 143h. Therefore, the other end of the seal member side supply passage 69 faces the sliding portion between the rotation side sliding surface 82 and the fixed side sliding surface 92 in the radial direction of the high speed side shaft 31. Then, oil is injected from the other end of the seal member side supply passage 69 into the small diameter hole 142h.

  As shown in FIG. 4, a plurality of communication grooves 93 are formed on the stationary-side sliding surface 92 of the stationary ring 91. The plurality of communication grooves 93 are arranged at equal intervals in the circumferential direction of the high speed side shaft 31. Each communication groove 93 is located on the outer side in the radial direction of the high speed side shaft 31 with respect to the seal surface 92 s of the fixed side sliding surface 92. Each communication groove 93 extends in the radial direction of the high-speed shaft 31 and communicates with the outer peripheral side of the stationary ring 91. Specifically, each communication groove 93 opens into the notch recess 91b.

  A plurality of positive pressure generating grooves 94 are formed on the fixed-side sliding surface 92 of the fixed ring 91. Each positive pressure generating groove 94 is located on the radially outer side of the high speed side shaft 31 with respect to the seal surface 92 s of the fixed side sliding surface 92. Each positive pressure generation groove 94 communicates with each communication groove 93. Therefore, each communication groove 93 functions as a first communication groove communicating with each positive pressure generation groove 94.

  Each positive pressure generating groove 94 extends from each communication groove 93 in the rotation direction of the rotary ring 81 (the direction indicated by the arrow R1 in FIG. 4). Each positive pressure generating groove 94 extends in the circumferential direction of the high speed side shaft 31 between the communication grooves 93 adjacent in the circumferential direction of the high speed side shaft 31. Each positive pressure generating groove 94 communicates with a communication groove 93 located in a direction opposite to the rotation direction of the rotary ring 81 among the communication grooves 93 adjacent to each other in the circumferential direction of the high-speed shaft 31 and rotates the rotary ring 81. The communication groove 93 positioned in the direction is not in communication.

  Each positive pressure generation groove 94 has a positive pressure step surface 94 a at the end of each positive pressure generation groove 94 opposite to the communication groove 93. The fixed-side sliding surface 92 has a positive pressure flat surface 92 a that is continuous with the positive pressure step surface 94 a of each positive pressure generating groove 94 in the rotation direction of the rotary ring 81. Each of the positive pressure flat surfaces 92a includes a communication groove 93 and a positive pressure generation groove that are not in communication with the positive pressure generation groove 94 among the communication grooves 93 adjacent to each other in the circumferential direction of the high speed side shaft 31 on the fixed-side sliding surface 92. It is a site | part located between 94 positive pressure level | step difference surfaces 94a.

  A negative pressure generating groove 95 is formed on the fixed-side sliding surface 92 of the fixed ring 91. The negative pressure generating groove 95 is located on the radially outer side of the high speed side shaft 31 with respect to the seal surface 92 s of the fixed side sliding surface 92. The negative pressure generating groove 95 is located on the radially inner side of the high speed side shaft 31 with respect to each positive pressure generating groove 94. The negative pressure generation groove 95 communicates with one communication groove 93 among the plurality of communication grooves 93, and extends in the direction opposite to the rotation direction of the rotary ring 81 from the communication groove 93. Yes. Accordingly, the communication groove 93 that communicates with the negative pressure generation groove 95 functions as a first communication groove that communicates with the positive pressure generation groove 94 and a second communication groove that communicates with the negative pressure generation groove 95.

  The negative pressure generation groove 95 has a negative pressure step surface 95 a at the end of the negative pressure generation groove 95 opposite to the communication groove 93. The fixed-side sliding surface 92 has a negative pressure flat surface 92b that is continuous with the negative pressure step surface 95a in the direction opposite to the rotation direction of the rotary ring 81. The negative pressure generating groove 95 is different from the rotation direction of the rotary ring 81 from the communication groove 93 so that the position of the connection position 95b with the communication groove 93 and the position of the negative pressure step surface 95a are offset in the radial direction of the high speed side shaft 31. It extends over 360 degrees toward the opposite direction.

  The negative pressure generation groove 95 has an overlap groove 96 that overlaps the negative pressure flat surface 92b in the radial direction of the high speed side shaft 31. The overlap groove 96 is located on the radially outer side of the high-speed side shaft 31 with respect to the negative pressure flat surface 92b. In the present embodiment, the overlap groove 96 communicates so that the negative pressure generating groove 95 is offset in the radial direction of the high-speed shaft 31 at the position of the connection position 95b with the communication groove 93 and the position of the negative pressure step surface 95a. It is formed by extending over 360 degrees or more in the direction opposite to the rotation direction of the rotary ring 81 from the groove 93. The depth of each communication groove 93 is deeper than the depth of each positive pressure generation groove 94 and the depth of the negative pressure generation groove 95. Further, the depth of each positive pressure generating groove 94 and the depth of the negative pressure generating groove 95 are substantially the same.

  The stationary ring 91 is positioned in the shaft insertion hole 14h so that one of the plurality of communication grooves 93 is opposed to the other end of the seal member side supply passage 69 in the radial direction of the high speed side shaft 31. ing. The oil sprayed from the other end of the seal member side supply passage 69 is supplied to the communication groove 93 facing the other end of the seal member side supply passage 69 in the radial direction of the high speed side shaft 31 to generate positive pressure. It is supplied to the groove 94.

  As shown in FIG. 5A, when the rotating ring 81 rotates with the rotation of the high-speed side shaft 31, the oil supplied into the positive pressure generating groove 94 via the communication groove 93 is changed to that shown in FIG. ), As indicated by an arrow T1, it moves toward the positive pressure step surface 94a following the rotation of the rotary ring 81, and moves over the positive pressure step surface 94a toward the positive pressure flat surface 92a. As a result, a positive pressure is generated between the rotating side sliding surface 82 and the fixed side sliding surface 92, and the interval between the rotating side sliding surface 82 and the fixed side sliding surface 92 is widened, thereby rotating the rotating side sliding surface. An oil film is formed by oil between 82 and the fixed side sliding surface 92, and the slidability between the rotating side sliding surface 82 and the seal surface 92s of the fixed side sliding surface 92 is improved. The oil interposed between the rotating ring 81 and the fixed ring 91 moves following the rotation of the rotating ring 81, whereby oil is supplied to each communication groove 93 and each normal groove is connected to each positive groove 93. Oil is supplied to the pressure generating groove 94.

  As shown in FIG. 5B, when the rotating ring 81 rotates with the rotation of the high speed side shaft 31, it is interposed between the rotating side sliding surface 82 and the negative pressure flat surface 92b of the fixed side sliding surface 92. The oil to be moved follows the rotation of the rotary ring 81 and flows into the negative pressure generating groove 95 through the negative pressure stepped surface 95a as indicated by an arrow T2 in FIG. 5B. As a result, the negative pressure generating groove 95 has a negative pressure, and oil that is about to leak from the speed increaser chamber 13c into the impeller chamber 15b through the shaft insertion hole 14h is sucked into the negative pressure generating groove 95. It will be easier.

  Then, the oil sucked into the negative pressure generating groove 95 flows toward the communication groove 93 communicating with the negative pressure generating groove 95 following the rotation of the rotary ring 81, and the shaft is inserted through the communication groove 93. It is discharged to the outside in the radial direction of the high speed side shaft 31 from the outer peripheral surface of the stationary ring 91 in the hole 14h. As a result, the oil stored in the speed increaser chamber 13c is prevented from leaking into the impeller chamber 15b through the space between the rotating sliding surface 82 and the sealing surface 92s of the stationary sliding surface 92. The

Next, the operation of this embodiment will be described.
The oil that passes between the rotation-side sliding surface 82 and the negative pressure flat surface 92 b and tries to flow toward the sealing surface 92 s is sucked by the overlap groove 96. Accordingly, it is possible to suppress the oil from flowing between the rotation-side sliding surface 82 and the negative pressure flat surface 92b and flowing toward the sealing surface 92s.

In the above embodiment, the following effects can be obtained.
(1) The negative pressure generating groove 95 has an overlap groove 96 that overlaps the negative pressure flat surface 92b in the radial direction of the high speed side shaft 31. According to this, the oil that passes between the rotation side sliding surface 82 and the negative pressure flat surface 92 b and tries to flow toward the seal surface 92 s can be sucked by the overlap groove 96. Therefore, the oil passes between the rotation side sliding surface 82 and the negative pressure flat surface 92b and flows toward the seal surface 92s, and the oil in the speed increasing machine chamber 13c is transferred to the rotation side sliding surface 82 and the seal surface. It is possible to suppress leakage into the impeller chamber 15b through the space between 92s.

  (2) The overlap groove 96 includes a communication groove 93 such that the negative pressure generating groove 95 is offset in the radial direction of the high-speed shaft 31 from the position of the connection position 95b with the communication groove 93 and the position of the negative pressure step surface 95a. Is formed by extending over 360 degrees in a direction opposite to the rotation direction of the rotary ring 81. According to this, the negative pressure generating groove 95 having the overlap groove 96 can be easily formed.

  (3) The oil passes between the rotation side sliding surface 82 and the negative pressure flat surface 92b and flows toward the seal surface 92s, and the oil in the speed increasing machine chamber 13c is sealed with the rotation side sliding surface 82 and the seal. Since leakage into the impeller chamber 15b through the space between the surfaces 92s can be suppressed, the amount of oil supplied to the mechanical seal 71 can be increased. Therefore, it is possible to easily improve the slidability between the rotation-side sliding surface 82 and the sealing surface 92s of the fixed-side sliding surface 92.

  (4) Since leakage of oil from the speed increaser chamber 13c to the impeller chamber 15b is suppressed, the oil is suppressed from being supplied to the fuel cell together with the air compressed by the centrifugal compressor 10, and the fuel It can avoid that the power generation efficiency of a battery falls.

  (5) For example, without forming the negative pressure generating groove 95 on the stationary-side sliding surface 92 of the stationary ring 91, the pumping action of returning the oil to the outer peripheral side by the relative rotational sliding of the rotating ring 81 and the stationary ring 91. It is conceivable that the spiral groove to be generated is formed over the entire circumference at a position surrounding the sealing surface 92s of the fixed-side sliding surface 92. In this case, when air is compressed as the impeller 24 rotates and the pressure in the impeller chamber 15b increases, the air in the impeller chamber 15b is likely to leak into the speed increaser chamber 13c through the spiral groove, and the speed increaser chamber The pressure in 13c may rise. For example, when the impeller 24 rotates 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 speed increaser chamber 13c. Then, the pumping action by the spiral groove does not function, and there is a possibility that the oil in the speed increaser chamber 13c leaks into the impeller chamber 15b through the shaft insertion hole 14h. However, in the present embodiment, the negative pressure generating groove 95 is formed on the fixed-side sliding surface 92 without using the spiral groove that generates the pumping action, and the speed increase is made in the negative pressure generating groove 95 that becomes negative pressure. By sucking oil from the machine chamber 13c through the shaft insertion hole 14h into the impeller chamber 15b, oil leakage into the impeller chamber 15b is suppressed. Therefore, even if the air is compressed with the rotation of the impeller 24 and the pressure in the impeller chamber 15b increases, the air in the impeller chamber 15b is unlikely to leak into the speed increaser chamber 13c through the shaft insertion hole 14h. Therefore, for example, when the impeller 24 is rotating at a low speed or when the operation of the centrifugal compressor 10 is stopped, a condition in which the pressure in the impeller chamber 15b is lower than the pressure in the speed increaser chamber 13c. Even if it becomes, it can suppress that the oil in the gear box 13c leaks out to the impeller chamber 15b via the shaft insertion hole 14h.

In addition, you may change the said embodiment as follows.
As shown in FIG. 6, two negative pressure generating grooves 95 </ b> A may be formed on the fixed-side sliding surface 92. One of the two negative pressure generating grooves 95A is surrounded by the other of the two negative pressure generating grooves 95A. The positions of the negative pressure step surfaces 95 a of the two negative pressure generating grooves 95 </ b> A are located on opposite sides of the high speed side shaft 31 in the radial direction of the high speed side shaft 31. Therefore, the negative pressure flat surface 92b that continues in the direction opposite to the rotation direction of the rotary ring 81 with respect to one negative pressure step surface 95a of the two negative pressure generation grooves 95A, and the other of the two negative pressure generation grooves 95A. The negative pressure flat surface 92b that is continuous in the direction opposite to the rotation direction of the rotary ring 81 with respect to the negative pressure step surface 95a is located on the opposite side in the radial direction with the high-speed shaft 31 interposed therebetween. The fixed sliding surface 92 has a communicating groove 93 that communicates with one end of the two negative pressure generating grooves 95A on the side opposite to the negative pressure stepped surface 95a and the other of the two negative pressure generating grooves 95A. A connection groove 921 is formed to connect the two.

  One of the two negative pressure generating grooves 95A has a negative pressure flat surface 92b that is continuous with the other negative pressure step surface 95a of the two negative pressure generating grooves 95A in the direction opposite to the rotation direction of the rotary ring 81. An overlap groove 96 </ b> A that overlaps on the radially inner side of the high-speed shaft 31 is provided. The other of the two negative pressure generating grooves 95A is a negative pressure flat surface 92b that is continuous with the negative pressure step surface 95a of the two negative pressure generating grooves 95A in the direction opposite to the rotation direction of the rotary ring 81. On the other hand, it has an overlap groove 96 </ b> A that overlaps on the radially outer side of the high-speed side shaft 31. According to this, the oil which passes between the rotation side sliding surface 82 and each negative pressure flat surface 92b and tries to flow toward the sealing surface 92s is sucked by each overlap groove 96A. Therefore, it is possible to suppress the oil from flowing between the rotation side sliding surface 82 and each negative pressure flat surface 92b and flowing toward the seal surface 92s.

  In the embodiment, a plurality of negative pressure generating grooves may be formed on the stationary-side sliding surface 92 of the stationary ring 91. For example, as shown in FIG. 7, two negative pressure generating grooves 95 </ b> B are formed on the fixed-side sliding surface 92 of the fixed ring 91. The two negative pressure generating grooves 95 </ b> B communicate with the respective communication grooves 93 positioned on the opposite sides in the radial direction with the high speed side shaft 31 interposed therebetween. One negative pressure step surface 95a of the two negative pressure generation grooves 95B is located on the radially inner side of the high speed side shaft 31 with respect to the other of the two negative pressure generation grooves 95B, and the other of the two negative pressure generation grooves 95B. Is located in a direction opposite to the rotation direction of the rotary ring 81 with respect to the communication groove 93 that communicates with each other. The other negative pressure step surface 95a of the two negative pressure generation grooves 95B is located on the radially inner side of the high speed side shaft 31 with respect to one of the two negative pressure generation grooves 95B, and the two negative pressure generation grooves 95B. One of the two is located in a direction opposite to the rotation direction of the rotary ring 81 with respect to the communication groove 93 that communicates.

  One of the two negative pressure generating grooves 95B has a negative pressure flat surface 92b that is continuous with the other negative pressure step surface 95a of the two negative pressure generating grooves 95B in the direction opposite to the rotation direction of the rotary ring 81. It has an overlap groove 96 </ b> B that overlaps on the radially outer side of the high speed side shaft 31. The other of the two negative pressure generating grooves 95B is a negative pressure flat surface 92b that is continuous with the negative pressure step surface 95a of the two negative pressure generating grooves 95B in the direction opposite to the rotation direction of the rotary ring 81. On the other hand, it has an overlap groove 96 </ b> B that overlaps on the radially outer side of the high-speed side shaft 31. According to this, the oil which passes between the rotation side sliding surface 82 and each negative pressure flat surface 92b and is going to flow toward the sealing surface 92s is sucked by each overlap groove 96B. Therefore, it is possible to suppress the oil from flowing between the rotation side sliding surface 82 and each negative pressure flat surface 92b and flowing toward the seal surface 92s.

In the embodiment, the overlap groove 96 may be located on the radially inner side of the high speed side shaft 31 with respect to the negative pressure flat surface 92b.
In the embodiment, the first communication groove that communicates with the positive pressure generation groove 94 and the second communication groove that communicates with the negative pressure generation groove 95 are separately formed on the stationary sliding surface 92 of the stationary ring 91. It may be. In this case, the first communication groove and the second communication groove communicate with the outer peripheral side of the stationary ring 91.

In the embodiment, the depth of each positive pressure generating groove 94 may be deeper than the depth of the negative pressure generating groove 95. Further, the depth of each positive pressure generating groove 94 may be shallower than the depth of the negative pressure generating groove 95.
In the embodiment, the numbers of the communication grooves 93 and the positive pressure generation grooves 94 may be changed as appropriate.

In the embodiment, the rotary ring 81 may be a separate member from the high speed side shaft 31.
In the embodiment, the application target of 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. Moreover, the mounting object of the centrifugal compressor 10 is not limited to the vehicle and is arbitrary.

  DESCRIPTION OF SYMBOLS 10 ... Centrifugal compressor, 11 ... Housing, 13c ... Speed increaser chamber, 14 ... Plate which is a partition wall, 14h ... Shaft insertion hole, 15b ... Impeller chamber, 16 ... Low speed side shaft, 24 ... Impeller, 30 ... Speed increase 31 ... high speed side shaft, 60 ... oil supply passage, 71 ... mechanical seal, 81 ... rotary ring, 81a ... end face, 82 ... rotation side sliding face, 91 ... fixed ring, 91a ... end face, 92 ... fixed side slide Moving surface, 92a ... positive pressure flat surface, 92b ... negative pressure flat surface, 92s ... sealing surface, 93 ... communication groove functioning as first communication groove and second communication groove, 94 ... positive pressure generating groove, 94a ... positive pressure Step surface, 95, 95A, 95B ... negative pressure generating groove, 95a ... negative pressure step surface, 96, 96A, 96B ... overlap groove.

Claims (2)

A low speed shaft,
An impeller attached to the high speed side shaft;
A speed increaser for transmitting the power of the low speed side shaft to the high speed side shaft;
An impeller chamber that houses the impeller, and a housing in which a gearbox that houses the gearbox is formed;
A partition wall that partitions the impeller chamber and the speed increaser chamber;
A shaft insertion hole formed in the partition wall and through which the high-speed side shaft is inserted;
An oil supply passage for supplying oil to the speed increaser;
A mechanical seal provided in the shaft insertion hole,
The mechanical seal is
A rotary ring that rotates integrally with the high speed side shaft, and is disposed to face the rotary ring in the axial direction of the high speed side shaft and is fixed to the shaft insertion hole in a state of surrounding the high speed side shaft. A fixed ring, and
The end surface on the fixed ring side of the rotating ring has a flat rotating side sliding surface that slides with the fixed ring, and the end surface on the rotating ring side of the fixed ring is the rotating side sliding surface. And the fixed side sliding surface has a sealing surface with the rotating side sliding surface.
The fixed sliding surface is formed with a positive pressure generating groove, a negative pressure generating groove, a first communication groove communicating with the positive pressure generating groove, and a second communication groove communicating with the negative pressure generating groove, The positive pressure generating groove, the negative pressure generating groove, the first communication groove, and the second communication groove are located on the radially outer side of the high speed side shaft with respect to the seal surface,
The first communication groove and the second communication groove communicate with the outer peripheral side of the stationary ring,
The positive pressure generation groove extends from the first communication groove in the rotation direction of the rotary ring and has a positive pressure step surface at an end of the positive pressure generation groove opposite to the first communication groove. ,
The negative pressure generation groove extends from the second communication groove in a direction opposite to the rotation direction of the rotary ring, and a negative pressure step at an end of the negative pressure generation groove opposite to the second communication groove. Has a surface,
The fixed-side sliding surface includes a positive pressure flat surface that is continuous in the rotation direction of the rotary ring with respect to the positive pressure step surface, and a reverse direction of the rotation direction of the rotary ring with respect to the negative pressure step surface. A centrifugal compressor having a continuous negative pressure flat surface,
The centrifugal compressor is characterized in that the negative pressure generating groove has an overlap groove that overlaps the flat surface of the negative pressure in the radial direction of the high speed side shaft.   The overlap groove includes the second communication groove so that the negative pressure generating groove is offset in the radial direction of the high-speed side shaft from the position where the negative pressure step surface is connected to the connection position with the second communication groove. 2. The centrifugal compressor according to claim 1, wherein the centrifugal compressor is formed by extending over 360 degrees or more in a direction opposite to a rotation direction of the rotary ring.