Fluid Machinery

Abstract

To improve reliability of a fluid machine.SOLUTION: A partition wall 29 includes an oil passage 60 for circulating oil by pump action by engagement of a driving gear 18 and a driven gear 19. The oil passage 60 has: an outer peripheral passage 61 surrounding a gear chamber 24; a supply passage 62 communicating the gear chamber 24 with the outer peripheral passage 61 and supplying the oil from the outer peripheral passage 61 to the gear chamber 24; and a discharge passage 63 for discharging the oil from the gear chamber 24 to the outer peripheral passage 61. The outer peripheral passage 61 has: a first circulation passage 64 surrounding the driving gear 18; and a second circulation passage 65 surrounding the driven gear 19. The discharge passage 63 is connected to a branching position to the first circulation passage 64 and the second circulation passage 65. The supply passage 62 is connected to a merging position from the first circulation passage 64 and the second circulation passage 65. A shock-absorbing protrusion 66 for easing collision of the oil caused by merging is formed in the outer peripheral passage 61 at the merging position.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a fluid machine. [Background technology]

[0002] The fluid machine has a cylindrical housing. In addition, as in Patent Document 1, for example, the fluid machine may have a first rotating shaft, a second rotating shaft, a drive gear, and a driven gear. The first rotating shaft and the second rotating shaft are rotatably supported in a state in which they are arranged parallel to each other in the housing. The drive gear is fixed to the first rotating shaft. The driven gear is fixed to the second rotating shaft. The driven gear meshes with the drive gear. The housing has a cylindrical partition wall that partitions a gear chamber inside. The gear chamber accommodates the drive gear and the driven gear. In addition, oil is sealed in the gear chamber. The oil contributes to lubrication between the drive gear and the driven gear. Furthermore, the housing has a pressure relief passage. The pressure relief passage releases pressure in the gear chamber to the outside. This prevents the inside of the gear chamber from becoming high pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-21333 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a fluid machine, if oil bubbles are generated in the gear chamber, the oil bubbles may leak out through the pressure relief passage. If the oil bubbles generated in the gear chamber leak out through the pressure relief passage, the amount of oil sealed in the gear chamber will decrease accordingly. This may result in poor lubrication between the drive gear and the driven gear, which may reduce the reliability of the fluid machine. [Means for solving the problem]

[0005] The fluid machine that solves the above problem includes a cylindrical housing, a first rotating shaft and a second rotating shaft that are rotatably supported in the housing while being arranged parallel to each other, a drive gear fixed to the first rotating shaft, and a driven gear fixed to the second rotating shaft and meshing with the drive gear, the housing including a cylindrical partition wall that accommodates the drive gear and the driven gear and defines a gear chamber in which oil is sealed, and a pressure relief passage that relieves pressure in the gear chamber to the outside, the partition wall including an oil passage that circulates the oil by a pumping action caused by meshing of the drive gear and the driven gear, the oil passage including the oil supply passage connects the gear chamber to the outer circumferential passage and supplies the oil from the outer circumferential passage to the gear chamber; and a discharge passage for discharging the oil from the gear chamber to the outer circumferential passage, the outer circumferential passage having a first orbital passage surrounding the drive gear and a second orbital passage surrounding the driven gear, the discharge passage being connected to a branch position to the first orbital passage and the second orbital passage, the supply passage being connected to a junction position from the first orbital passage and the second orbital passage, and the outer circumferential passage at the junction position is formed with a cushioning protrusion for mitigating collision of oil due to junction.

[0006] According to this, the oil circulates through the oil passage by the pumping action caused by the meshing of the drive gear and the driven gear, so that the drive gear and the driven gear can be well lubricated. When the drive gear and the driven gear rotate, the oil in the gear chamber is discharged through the discharge passage to the outer circumferential passage. The oil discharged to the outer circumferential passage is diverted to the first and second orbital passages at the diverging position. The oil flowing through the first and second orbital passages merge at the merging position. At this time, the collision of the oil caused by the merging is mitigated by the buffer convex portion. This suppresses the generation of bubbles due to the collision of the oil. Then, the oil is supplied to the gear chamber through the supply passage in a state in which the generation of oil bubbles is suppressed. Therefore, the generation of oil bubbles in the gear chamber is suppressed. Therefore, the problem that the oil bubbles generated in the gear chamber leak to the outside through the depressurization passage and the amount of oil sealed in the gear chamber is reduced by that amount is easily avoided. As a result, the lubrication between the drive gear and the driven gear is suppressed from becoming poor, so that the reliability of the fluid machine can be improved.

[0007] In the above fluid machine, the buffer protrusion has a pair of curved surfaces that curve gradually toward each other, and the curved surfaces may have a first curved surface that changes the inflow direction of oil supplied from the first circular passage to the supply passage, and a second curved surface that changes the inflow direction of oil supplied from the second circular passage to the supply passage.

[0008] According to this, the first curved surface can create a flow with less loss in the oil supplied from the first circular passage to the supply passage, and the second curved surface can create a flow with less loss in the oil supplied from the second circular passage to the supply passage.

[0009] In the above fluid machine, the buffer protrusion may have a flat surface facing the supply passage, and the joining position may be defined by at least the flat surface. According to this, since the buffer protrusion has a flat surface facing the supply passage, the collision of the oil flowing through the first and second circulation passages is mitigated when the oil flowing through the first and second circulation passages join at the joining position, which makes it easier to further suppress the generation of bubbles due to the collision of the oil.

[0010] In the above fluid machine, it is preferable that the first rotating shaft is supported relative to the housing by a first bearing, the second rotating shaft is supported relative to the housing by a second bearing, and an oil supply passage is formed in the housing to supply the oil from the outer circumferential passage to the first bearing and the second bearing.

[0011] According to this, since oil can be supplied from the outer peripheral passage through the oil supply passage to the first bearing and the second bearing, the first bearing and the second bearing can be well lubricated, and therefore the reliability of the fluid machine can be further improved.

[0012] In the above fluid machine, the supply passage and the discharge passage may extend to face each other across a meshing portion where the drive gear and the driven gear mesh. This allows oil to be easily discharged from the meshing portion between the drive gear and the driven gear to the outer peripheral passage through the discharge passage, and allows oil to be easily supplied from the outer peripheral passage to the meshing portion between the drive gear and the driven gear through the supply passage. Therefore, the pumping action caused by the meshing of the drive gear and the driven gear makes it easier for oil to circulate through the oil passage, thereby further improving the lubrication of the drive gear and the driven gear. Effect of the Invention

[0013] According to the present invention, the reliability of the fluid machine can be improved. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view of a fluid machine according to an embodiment. [Diagram 2] 2 is a cross-sectional view taken along line 2-2 in FIG. 1. [Diagram 3] FIG. [Figure 4] 4 is a cross-sectional view taken along line 4-4 in FIG. [Diagram 5] FIG. [Figure 6] 6 is a cross-sectional view taken along line 6-6 in FIG. [Figure 7] 4 is an enlarged cross-sectional view of a portion of the rotor housing. FIG. [Figure 8] 11 is a diagram showing the positional relationship between an opening of a branch passage and teeth of a driven gear. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the fluid machine will be described below with reference to Fig. 1 to Fig. 8. The fluid machine of this embodiment is used as a hydrogen pump for a fuel cell that supplies hydrogen to a fuel cell that generates electricity by chemically reacting hydrogen, which is a fuel gas, with oxygen contained in air, which is an oxidant gas. The fluid machine is mounted on a fuel cell vehicle.

[0016] <Basic Configuration of Fluid Machine 10> As shown in FIG. 1, the fluid machine 10 has a cylindrical housing 11. The housing 11 has a motor housing 12, a gear housing 13, a rotor housing 14, and a cover member 15. The motor housing 12 has a plate-shaped end wall 12a and a cylindrical peripheral wall 12b. The peripheral wall 12b extends cylindrically from the outer periphery of the end wall 12a. The gear housing 13 has a plate-shaped end wall 13a and a cylindrical peripheral wall 13b. The peripheral wall 13b extends cylindrically from the outer periphery of the end wall 13a. The gear housing 13 is connected to an end of the peripheral wall 12b of the motor housing 12 on the opening side. The end wall 13a of the gear housing 13 closes the opening of the peripheral wall 12b of the motor housing 12. The end wall 12a of the motor housing 12, the peripheral wall 12b of the motor housing 12, and the end wall 13a of the gear housing 13 define a motor chamber S1. Therefore, the housing 11 has a motor chamber S1.

[0017] The rotor housing 14 has a plate-shaped end wall 14a and a cylindrical peripheral wall 14b. The peripheral wall 14b extends cylindrically from the outer periphery of the end wall 14a. The rotor housing 14 is connected to an end of the peripheral wall 13b of the gear housing 13 on the opening side. The rotor housing 14 and the gear housing 13 are sealed by an annular seal member 13s. The end wall 14a of the rotor housing 14 closes the opening of the peripheral wall 13b of the gear housing 13. The cover member 15 is plate-shaped. The cover member 15 is connected to an end of the peripheral wall 14b of the rotor housing 14 on the opening side. The cover member 15 closes the opening of the peripheral wall 14b of the rotor housing 14. The axial direction of the peripheral wall 12b of the motor housing 12, the axial direction of the peripheral wall 13b of the gear housing 13, and the axial direction of the peripheral wall 14b of the rotor housing 14 are all aligned.

[0018] The fluid machine 10 has a first rotating shaft 16 and a second rotating shaft 17. The first rotating shaft 16 and the second rotating shaft 17 are rotatably supported in a state in which they are arranged parallel to each other within the housing 11. The directions of the rotational axes of the first rotating shaft 16 and the second rotating shaft 17 coincide with the axial directions of the peripheral walls 12b, 13b, and 14b.

[0019] The fluid machine 10 has a drive gear 18 and a driven gear 19. The drive gear 18 is disk-shaped. The drive gear 18 is fixed to a first rotating shaft 16. The driven gear 19 is disk-shaped. The driven gear 19 is fixed to a second rotating shaft 17. The driven gear 19 meshes with the drive gear 18. In the following description, the portion where the drive gear 18 and the driven gear 19 mesh with each other may be referred to as an "engagement portion 28."

[0020] The fluid machine 10 has a drive rotor 20 and a driven rotor 21. The drive rotor 20 is provided on the first rotating shaft 16. The driven rotor 21 is provided on the second rotating shaft 17. The driven rotor 21 meshes with the drive rotor 20.

[0021] The fluid machine 10 includes an electric motor 22. The electric motor 22 rotates the first rotating shaft 16. The electric motor 22 is accommodated in the motor chamber S1. Thus, the motor chamber S1 accommodates the electric motor 22. The electric motor 22 includes a motor rotor 22a and a stator 22b. The motor rotor 22a is cylindrical. The motor rotor 22a is fixed to the first rotating shaft 16 so as to be rotatable integrally therewith. The stator 22b is cylindrical. The stator 22b is fixed to an inner circumferential surface of the peripheral wall 12b of the motor housing 12. The stator 22b surrounds the motor rotor 22a. The stator 22b includes a coil 22c. The coil 22c is wound around teeth (not shown) of the stator 22b. The electric motor 22 is driven by power being supplied to the coil 22c. When the electric motor 22 is driven, the motor rotor 22a rotates integrally with the first rotating shaft 16.

[0022] The housing 11 has a gear chamber 24. The gear chamber 24 is defined by an end wall 13a of the gear housing 13, a peripheral wall 13b of the gear housing 13, and an end wall 14a of the rotor housing 14. Thus, the end wall 13a of the gear housing 13, the peripheral wall 13b of the gear housing 13, and the end wall 14a of the rotor housing 14 form a cylindrical partition wall 29 that defines the gear chamber 24. Thus, the housing 11 has the partition wall 29. The gear chamber 24 accommodates a drive gear 18 and a driven gear 19. The drive gear 18 and the driven gear 19 are accommodated in the gear chamber 24 in a state of meshing with each other. Oil is sealed in the gear chamber 24. The oil contributes to lubrication between the drive gear 18 and the driven gear 19.

[0023] The housing 11 has a rotor chamber 25. The rotor chamber 25 is defined by an end wall 14a of the rotor housing 14, a peripheral wall 14b of the rotor housing 14, and a cover member 15. The rotor chamber 25 accommodates a drive rotor 20 and a driven rotor 21. The drive rotor 20 and the driven rotor 21 are accommodated in the rotor chamber 25 in a state of meshing with each other. The motor chamber S1, the gear chamber 24, and the rotor chamber 25 are arranged in this order in the direction of the rotation axis of the first rotating shaft 16.

[0024] A first hole 31 is formed in the end wall 13a of the gear housing 13. The first hole 31 penetrates the end wall 13a of the gear housing 13 in the thickness direction. The first hole 31 is a circular hole. The first hole 31 includes a first bearing accommodating hole 31a and a first seal accommodating hole 31b. The first bearing accommodating hole 31a and the first seal accommodating hole 31b are in communication with each other. The first bearing accommodating hole 31a is located closer to the gear chamber 24 than the first seal accommodating hole 31b. The first bearing accommodating hole 31a opens to an end face 13e of the end wall 13a of the gear housing 13 on the gear chamber 24 side. Therefore, the first bearing accommodating hole 31a is in communication with the gear chamber 24. The first seal accommodating hole 31b is located closer to the motor chamber S1 than the first bearing accommodating hole 31a.

[0025] A second hole 32 is formed in the end wall 13a of the gear housing 13. The second hole 32 is a recess formed in the end surface 13e of the end wall 13a of the gear housing 13. The second hole 32 has a circular hole shape.

[0026] A third hole 33 is formed in the end wall 14a of the rotor housing 14. The third hole 33 penetrates the end wall 14a of the rotor housing 14 in the thickness direction. The third hole 33 is a circular hole. The axis of the third hole 33 coincides with the axis of the first hole 31. The third hole 33 includes a third bearing accommodating hole 33a and a third seal accommodating hole 33b. The third bearing accommodating hole 33a and the third seal accommodating hole 33b are in communication with each other. The third bearing accommodating hole 33a is located closer to the gear chamber 24 than the third seal accommodating hole 33b. The third bearing accommodating hole 33a opens to an end face 14e of the end wall 14a of the rotor housing 14 on the gear chamber 24 side. Therefore, the third bearing accommodating hole 33a is in communication with the gear chamber 24. The third seal accommodating hole 33b is located closer to the rotor chamber 25 than the third bearing accommodating hole 33a.

[0027] A fourth hole 34 is formed in the end wall 14a of the rotor housing 14. The fourth hole 34 penetrates the end wall 14a of the rotor housing 14 in the thickness direction. The fourth hole 34 is a circular hole. The axis of the fourth hole 34 coincides with the axis of the second hole 32. The axis of the third hole 33 and the axis of the fourth hole 34 extend parallel to each other. The fourth hole 34 includes a fourth bearing accommodating hole 34a and a fourth seal accommodating hole 34b. The fourth bearing accommodating hole 34a and the fourth seal accommodating hole 34b communicate with each other. The fourth bearing accommodating hole 34a is located closer to the gear chamber 24 than the fourth seal accommodating hole 34b. The fourth bearing accommodating hole 34a opens to an end surface 14e of the end wall 14a of the rotor housing 14. Thus, the fourth bearing accommodating hole 34a communicates with the gear chamber 24. The fourth seal receiving hole 34b is located closer to the rotor chamber 25 than the fourth bearing receiving hole 34a.

[0028] The fluid machine 10 includes a first bearing 41. The first bearing 41 is accommodated in the first bearing accommodating hole 31a. The first bearing 41 is held in the first bearing accommodating hole 31a. The first bearing 41 is, for example, a rolling bearing. The first bearing 41 rotatably supports the first rotating shaft 16. Therefore, the first rotating shaft 16 is supported with respect to the housing 11 by the first bearing 41.

[0029] The fluid machine 10 includes a first seal member 41s. The first seal member 41s is accommodated in the first seal accommodating hole 31b. The first seal member 41s is annular. The first seal member 41s seals between the gear chamber 24 and the motor chamber S1.

[0030] The fluid machine 10 includes a second bearing 42. The second bearing 42 is accommodated in the second hole 32. The second bearing 42 is held in the second hole 32. The second bearing 42 is, for example, a rolling bearing. The second bearing 42 rotatably supports the second rotating shaft 17. Therefore, the second rotating shaft 17 is supported with respect to the housing 11 by the second bearing 42.

[0031] The fluid machine 10 includes a third bearing 43. The third bearing 43 is accommodated in the third bearing accommodating hole 33a. The third bearing 43 is held in the third bearing accommodating hole 33a. The third bearing 43 is, for example, a rolling bearing. The third bearing 43 rotatably supports the first rotating shaft 16. Therefore, the first rotating shaft 16 is supported with respect to the housing 11 by the third bearing 43.

[0032] The fluid machine 10 includes a third seal member 43s. The third seal member 43s is accommodated in the third seal accommodating hole 33b. The third seal member 43s is annular. The third seal member 43s seals between the gear chamber 24 and the rotor chamber 25.

[0033] The fluid machine 10 includes a fourth bearing 44. The fourth bearing 44 is accommodated in the fourth bearing accommodating hole 34a. The fourth bearing 44 is held in the fourth bearing accommodating hole 34a. The fourth bearing 44 is, for example, a rolling bearing. The fourth bearing 44 rotatably supports the second rotating shaft 17. Therefore, the second rotating shaft 17 is supported with respect to the housing 11 by the fourth bearing 44.

[0034] The fluid machine 10 includes a fourth seal member 44s. The fourth seal member 44s is accommodated in the fourth seal accommodating hole 34b. The fourth seal member 44s is annular. The fourth seal member 44s seals between the gear chamber 24 and the rotor chamber 25.

[0035] A bearing portion 35 is formed in the end wall 12a of the motor housing 12. The bearing portion 35 is cylindrical and protrudes from an end face of the end wall 12a of the motor housing 12 on the motor chamber S1 side. The axis of the bearing portion 35 coincides with the axis of the first hole 31.

[0036] The fluid machine 10 includes a fifth bearing 45. The fifth bearing 45 is accommodated in the bearing portion 35. The fifth bearing 45 is held in the bearing portion 35. The fifth bearing 45 is, for example, a rolling bearing. The fifth bearing 45 rotatably supports the first rotating shaft 16. Therefore, the first rotating shaft 16 is supported with respect to the housing 11 by the fifth bearing 45.

[0037] A first end of the first rotating shaft 16 is disposed inside the bearing portion 35. The first end of the first rotating shaft 16 is rotatably supported by a fifth bearing 45. A second end of the first rotating shaft 16 passes through the first hole 31 and the third hole 33 and protrudes into the rotor chamber 25. The drive rotor 20 is attached to the second end of the first rotating shaft 16. Therefore, the second end of the first rotating shaft 16 is a free end. Therefore, the first rotating shaft 16 is cantilevered by the housing 11.

[0038] A first end of the second rotating shaft 17 is disposed in the second hole 32. The first end of the second rotating shaft 17 is rotatably supported by the second bearing 42. The second end of the second rotating shaft 17 passes through the fourth hole 34 and protrudes into the rotor chamber 25. The driven rotor 21 is attached to the second end of the second rotating shaft 17. Therefore, the second end of the second rotating shaft 17 is a free end. Therefore, the second rotating shaft 17 is supported in a cantilever manner by the housing 11.

[0039] 2, the drive rotor 20 and the driven rotor 21 are formed in a bilobal (gourd-shaped) cross section perpendicular to the rotation axis direction of the first rotating shaft 16 and the second rotating shaft 17. The drive rotor 20 has two lobe teeth 20a and a valley tooth 20b formed between the two lobe teeth 20a. The driven rotor 21 has two lobe teeth 21a and a valley tooth 21b formed between the two lobe teeth 21a.

[0040] The drive rotor 20 and the driven rotor 21 are capable of rotating within the rotor chamber 25 while repeatedly meshing the lobe teeth 20a of the drive rotor 20 with the valley teeth 21b of the driven rotor 21 and the valley teeth 20b of the drive rotor 20 with the lobe teeth 21a of the driven rotor 21. The drive rotor 20 rotates in the direction of arrow R1 shown in Fig. 2, and the driven rotor 21 rotates in the direction of arrow R2 shown in Fig. 2.

[0041] The fluid machine 10 has a suction port 26 and a discharge port 27. The suction port 26 and the discharge port 27 are formed in the peripheral wall 14b of the rotor housing 14. The suction port 26 and the discharge port 27 are formed in opposing positions on the peripheral wall 14b of the rotor housing 14 with the rotor chamber 25 in between. The suction port 26 and the discharge port 27 communicate between the rotor chamber 25 and the outside.

[0042] A linear direction Z1 connecting the suction port 26 and the discharge port 27 perpendicularly intersects with the rotational axes L1, L2 of the first rotating shaft 16 and the second rotating shaft 17. The fluid machine 10 is mounted on the fuel cell vehicle so that the discharge port 27 opens vertically downward. Therefore, the linear direction Z1 coincides with the vertical direction. The fluid machine 10 is mounted on the fuel cell vehicle so that the suction port 26 is located vertically above the discharge port 27.

[0043] When the first rotating shaft 16 is rotated by the drive of the electric motor 22, the second rotating shaft 17 rotates in the opposite direction to the first rotating shaft 16 via the gear connection of the drive gear 18 and the driven gear 19, which are meshed with each other. As a result, the drive rotor 20 and the driven rotor 21 rotate in the opposite directions while meshing with each other. With the rotation of the drive rotor 20 and the driven rotor 21, the fluid machine 10 draws fluid into the rotor chamber 25 via the suction port 26 and discharges the fluid from the rotor chamber 25 via the discharge port 27.

[0044] <Inner circumferential surface 13c of peripheral wall 13b of gear housing 13> As shown in FIG. 3 and FIG. 4, the inner peripheral surface 13c of the peripheral wall 13b of the gear housing 13 has a first inner peripheral surface 51 and a second inner peripheral surface 52. As shown in FIG. 4, the first inner peripheral surface 51 is an arc-shaped curved surface extending to surround the drive gear 18. Here, the portion of the first inner peripheral surface 51 located at the uppermost position in the vertical direction is defined as a top portion P1. Also, the portion of the first inner peripheral surface 51 located at the lowermost position in the vertical direction is defined as a bottom portion P2. The first inner peripheral surface 51 has an upper surface 51a, a lower surface 51b, and a connecting surface 51c. The upper surface 51a is a curved surface extending from the top portion P1 toward the meshing portion 28. The lower surface 51b is a curved surface extending from the bottom portion P2 toward the meshing portion 28. The connecting surface 51c is a curved surface extending between the top portion P1 and the bottom portion P2. The connection surface 51c connects the upper surface 51a and the lower surface 51b.

[0045] The second inner peripheral surface 52 is an arc-shaped curved surface that extends to surround the driven gear 19. Here, the portion of the second inner peripheral surface 52 that is located at the top in the vertical direction is defined as the apex P11. Also, the portion of the second inner peripheral surface 52 that is located at the bottom in the vertical direction is defined as the bottom P12. The second inner peripheral surface 52 has an upper surface 52a, a lower surface 52b, and a connecting surface 52c. The upper surface 52a is a curved surface that extends from the apex P11 toward the meshing portion 28. The lower surface 52b is a curved surface that extends from the bottom P12 toward the meshing portion 28. The connecting surface 52c is a curved surface that extends between the apex P11 and the bottom P12. The connecting surface 52c connects the upper surface 52a and the lower surface 52b.

[0046] The inner circumferential surface 13c of the peripheral wall 13b of the gear housing 13 has an upper bulging surface 53 and a lower bulging surface 54. The upper bulging surface 53 is located above the meshing portion 28. The upper bulging surface 53 connects the upper surface 51a of the first inner circumferential surface 51 and the upper surface 52a of the second inner circumferential surface 52. The upper bulging surface 53 is a curved surface that is convex from the upper surface 51a of the first inner circumferential surface 51 and the upper surface 52a of the second inner circumferential surface 52 toward the meshing portion 28.

[0047] The lower bulging surface 54 is located below the meshing portion 28. The lower bulging surface 54 connects the lower surface 51b of the first inner circumferential surface 51 and the lower surface 52b of the second inner circumferential surface 52. The lower bulging surface 54 is a curved surface that convexly extends from the lower surface 51b of the first inner circumferential surface 51 and the lower surface 52b of the second inner circumferential surface 52 toward the meshing portion 28.

[0048] <Upper Wall 55 and Lower Wall 56> The gear housing 13 has an upper wall portion 55 and a lower wall portion 56. The upper wall portion 55 is a wall portion of the gear housing 13 that is defined by an upper surface 51a of the first inner circumferential surface 51, an upper surface 52a of the second inner circumferential surface 52, and an upper bulging surface 53. The upper wall portion 55 is located above the meshing portion 28 and is disposed between the drive gear 18 and the driven gear 19. The upper wall portion 55 is located above the meshing portion 28 and is disposed so as to fill the space between the drive gear 18 and the driven gear 19 in the gear chamber 24.

[0049] The lower wall portion 56 is a wall portion of the gear housing 13 that is defined by the lower surface 51b of the first inner circumferential surface 51, the lower surface 52b of the second inner circumferential surface 52, and the lower bulging surface 54. The lower wall portion 56 is located below the meshing portion 28 and is disposed between the drive gear 18 and the driven gear 19. The lower wall portion 56 is located below the meshing portion 28 and is disposed so as to fill the space between the drive gear 18 and the driven gear 19 in the gear chamber 24.

[0050] <Oil passage 60> The partition wall 29 has an oil passage 60. As shown in Fig. 3, the oil passage 60 is formed in an open end surface 13f of the peripheral wall 13b of the gear housing 13. As shown in Figs. 3 and 4, the oil passage 60 has an outer circumferential passage 61, a supply passage 62, and a discharge passage 63. The outer circumferential passage 61 surrounds the gear chamber 24. The outer circumferential passage 61 has a first circumferential passage 64 and a second circumferential passage 65.

[0051] <First Loop Passage 64> The first circumferential passage 64 surrounds the first inner circumferential surface 51. Therefore, the first circumferential passage 64 surrounds the drive gear 18. The first circumferential passage 64 is configured by a groove formed in the open end surface 13f of the peripheral wall 13b of the gear housing 13.

[0052] A first end of the first circulating passage 64 is located inside the peripheral wall 13b of the gear housing 13 and vertically above the upper wall portion 55. The first end of the first circulating passage 64 is located vertically above the upper bulging surface 53.

[0053] A second end of the first circulating passage 64 is located inside the lower wall portion 56. The second end of the first circulating passage 64 is located vertically below the lower bulging surface 54. The second end of the first circulating passage 64 extends along the lower surface 51b of the first inner circumferential surface 51. The second end of the first circulating passage 64 curves from the portion of the first circulating passage 64 that is located vertically lowest toward the lower wall portion 56 so as to approach the lower bulging surface 54.

[0054] <Second Loop Passage 65> The second circulating passage 65 surrounds the second inner circumferential surface 52. Therefore, the second circulating passage 65 surrounds the driven gear 19. The second circulating passage 65 is configured by a groove formed in the open end surface 13f of the peripheral wall 13b of the gear housing 13.

[0055] A first end of the second circulating passage 65 is located vertically above the upper wall portion 55 inside the peripheral wall 13b of the gear housing 13. A first end of the first circulating passage 64 is located vertically above the upper bulging surface 53. The first end of the first circulating passage 64 and the first end of the second circulating passage 65 communicate with each other vertically above the upper wall portion 55 inside the peripheral wall 13b of the gear housing 13.

[0056] The second end of the second circulating passage 65 is located inside the lower wall portion 56. The second end of the second circulating passage 65 is located vertically below the lower bulging surface 54. The second end of the second circulating passage 65 extends along the lower surface 52b of the second inner circumferential surface 52. The second end of the second circulating passage 65 curves from the portion of the second circulating passage 65 that is located vertically lower toward the lower wall portion 56 so as to approach the lower bulging surface 54. The second end of the first circulating passage 64 and the second end of the second circulating passage 65 communicate with each other vertically below the lower bulging surface 54 inside the lower wall portion 56.

[0057] <Supply passage 62> The supply passage 62 is formed in the lower wall portion 56. The supply passage 62 is configured by a groove formed in the open end surface 13f of the peripheral wall 13b of the gear housing 13. A first end of the supply passage 62 is connected to a joining position of the second end of the first circumferential passage 64 and the second end of the second circumferential passage 65. Therefore, the supply passage 62 is connected to a joining position from the first circumferential passage 64 and the second circumferential passage 65. Therefore, the first end of the supply passage 62 is connected to the outer circumferential passage 61. A second end of the supply passage 62 opens to the lower bulging surface 54. And, the second end of the supply passage 62 is connected to the gear chamber 24. Thus, the supply passage 62 communicates between the gear chamber 24 and the outer circumferential passage 61. And, the supply passage 62 supplies oil from the outer circumferential passage 61 to the gear chamber 24. A second end of the supply passage 62 opens from the lower bulging surface 54 toward the meshing portion 28.

[0058] <Discharge passage 63> The discharge passage 63 is formed in the upper wall portion 55. The discharge passage 63 is configured by a groove formed in the open end surface 13f of the peripheral wall 13b of the gear housing 13. A first end of the discharge passage 63 is connected to a branching position of the first end of the first circumferential passage 64 and the first end of the second circumferential passage 65. Therefore, the discharge passage 63 is connected to a branching position to the first circumferential passage 64 and the second circumferential passage 65. Therefore, the first end of the discharge passage 63 is connected to the outer circumferential passage 61. A second end of the discharge passage 63 opens to the upper bulging surface 53. And, the second end of the discharge passage 63 is connected to the gear chamber 24. Thus, the discharge passage 63 is connected to the gear chamber 24 and the outer circumferential passage 61. And, the discharge passage 63 discharges oil from the gear chamber 24 to the outer circumferential passage 61. The second end of the discharge passage 63 opens from the upper bulging surface 53 toward the meshing portion 28.

[0059] The supply passage 62 and the discharge passage 63 are extended so as to face each other across the meshing portion 28 where the drive gear 18 and the driven gear 19 mesh. The supply passage 62 is located rearward of the meshing portion 28 in the rotation direction of the drive gear 18 and the driven gear 19. The discharge passage 63 is located forward of the meshing portion 28 in the rotation direction of the drive gear 18 and the driven gear 19.

[0060] <Cushioning protrusion 66> The oil passage 60 includes a buffer protrusion 66. The buffer protrusion 66 is provided in the outer peripheral passage 61 at a position where a second end of the first circulating passage 64 and a second end of the second circulating passage 65 join together. The buffer protrusion 66 is located vertically below the lower bulging surface 54 inside the peripheral wall 13b of the gear housing 13.

[0061] The buffer protrusion 66 has a pair of curved surfaces 66A. The pair of curved surfaces 66A are curved so as to gradually approach each other. The curved surfaces 66A have a first curved surface 66a and a second curved surface 66b. The first curved surface 66a changes the inflow direction of the oil supplied from the first circular passage 64 to the supply passage 62. The second curved surface 66b changes the inflow direction of the oil supplied from the second circular passage 65 to the supply passage 62. Furthermore, the buffer protrusion 66 has a flat surface 66c. The flat surface 66c faces the supply passage 62. The joining position of the second end of the first circular passage 64 and the second end of the second circular passage 65 is defined by at least the flat surface 66c.

[0062] In this way, the buffer protrusion 66 reduces the collision of oil caused by the joining of the oil flowing through the first circular passage 64 and the oil flowing through the second circular passage 65. Therefore, the buffer protrusion 66 that reduces the collision of oil caused by the joining is formed in the outer circumferential passage 61 at the joining position of the second end of the first circular passage 64 and the second end of the second circular passage 65.

[0063] <Oil supply passage 70> As shown in Fig. 3, an oil supply passage 70 is formed in the housing 11. The oil supply passage 70 includes an oil supply hole 70a, a first oil supply passage 71, and a second oil supply passage 72. The oil supply hole 70a is formed in the gear housing 13. A first end of the oil supply hole 70a communicates with a branch position between a first end of the first circulating passage 64 and a first end of the second circulating passage 65. A second end of the oil supply hole 70a is located inside the gear housing 13.

[0064] The first oil supply passage 71 is formed in the gear housing 13. A first end of the first oil supply passage 71 communicates with a second end of the oil supply hole 70a. The second end of the first oil supply passage 71 communicates with the first hole 31. Then, oil from the outer peripheral passage 61 is supplied to the first bearing 41 in the first hole 31 via the oil supply hole 70a and the first oil supply passage 71.

[0065] The second oil supply passage 72 is formed in the gear housing 13. A first end of the second oil supply passage 72 communicates with a second end of the oil supply hole 70a. A second end of the second oil supply passage 72 communicates with the second hole 32. Then, oil from the outer peripheral passage 61 is supplied to the second bearing 42 in the second hole 32 via the oil supply hole 70a and the second oil supply passage 72. In this way, the oil supply passage 70 supplies oil from the outer peripheral passage 61 to the first bearing 41 and the second bearing 42.

[0066] <Recess 75> As shown in Figures 5 and 6, the fluid machine 10 has a recess 75. The recess 75 is formed in an end face 14e of an end wall 14a of the rotor housing 14. The recess 75 is formed in a portion of the end face 14e of the end wall 14a of the rotor housing 14 that faces the upper wall portion 55 of the gear housing 13 in the axial direction of the first rotating shaft 16. The recess 75 communicates with the discharge passage 63. A portion of the oil flowing through the discharge passage 63 flows into the recess 75. The end face 14e of the end wall 14a of the rotor housing 14 closes the opening of the oil passage 60 except for the portion where the discharge passage 63 and the recess 75 communicate with each other.

[0067] A third oil supply passage 73 and a fourth oil supply passage 74 are formed in the end wall 14a of the rotor housing 14. The third oil supply passage 73 connects the recess 75 and the third hole 33. A part of the oil in the recess 75 is supplied to the third bearing 43 in the third hole 33 via the third oil supply passage 73. The fourth oil supply passage 74 connects the recess 75 and the fourth hole 34. A part of the oil in the recess 75 is supplied to the fourth bearing 44 in the fourth hole 34 via the fourth oil supply passage 74.

[0068] <Pressure relief passage 80> As shown in FIG. 7, the housing 11 is provided with a pressure relief passage 80. The pressure relief passage 80 is formed in the rotor housing 14. The pressure relief passage 80 has an opening 81, an enlarged diameter portion 82, and a pressure release passage 83. The opening 81 is a passage formed in the rotor housing 14. The opening 81 is, for example, a circular hole. A first end of the opening 81 communicates with the recess 75. The opening 81 communicates with the gear chamber 24 via the recess 75 and the discharge passage 63. Therefore, the opening 81 opens into the gear chamber 24. A second end of the opening 81 is located inside the rotor housing 14.

[0069] The enlarged diameter portion 82 is a passage formed inside the rotor housing 14. The enlarged diameter portion 82 is, for example, in the shape of a circular hole. The enlarged diameter portion 82 is continuous with the opening 81. The enlarged diameter portion 82 has an inner diameter larger than that of the opening 81. The pressure release passage 83 is formed in the rotor housing 14. A first end of the pressure release passage 83 is connected to the enlarged diameter portion 82. A second end of the pressure release passage 83 is open to the outside of the rotor housing 14. A ventilation membrane 83a is provided at the second end of the pressure release passage 83. The ventilation membrane 83a is a membrane that allows gas to pass through but does not allow liquid to pass through.

[0070] The air in the gear chamber 24 is discharged to the outside of the housing 11 through the exhaust passage 63, the recess 75, the opening 81, the enlarged diameter portion 82, and the pressure release passage 83. Therefore, the pressure relief passage 80 releases the pressure in the gear chamber 24 to the outside.

[0071] A return passage 76 is formed in the rotor housing 14. The return passage 76 connects the expanded diameter portion 82 and the fourth hole 34. The return passage 76 allows the oil in the expanded diameter portion 82 to flow into the fourth hole 34.

[0072] <Branch Path 85> The housing 11 is provided with a branch passage 85. A first end of the branch passage 85 communicates with the expanded diameter portion 82. Thus, the branch passage 85 is connected to the expanded diameter portion 82. As shown in FIG. 5, a second end of the branch passage 85 opens to an end face 14e of the end wall 14a of the rotor housing 14. And, the second end of the branch passage 85 communicates with the gear chamber 24. Thus, the branch passage 85 opens into the gear chamber 24 at a position different from the opening of the opening 81.

[0073] 8, the opening of the branch passage 85 on the gear chamber 24 side is provided to face the tooth 19a of the driven gear 19. Specifically, the opening of the branch passage 85 faces a portion between a root 19e of the tooth 19a of the rotating driven gear 19 and a tip 19f of the tooth 19a. As a result, a negative pressure is generated that draws the oil in the pressure relief passage 80 into the branch passage 85 by the rotation of the drive gear 18 and the driven gear 19. Therefore, the opening of the branch passage 85 on the gear chamber 24 side is provided to face the tooth 19a of the driven gear 19 so that a negative pressure is generated that draws the oil in the pressure relief passage 80 into the branch passage 85 by the rotation of the drive gear 18 and the driven gear 19.

[0074] [Operation of the embodiment] Next, the operation of this embodiment will be described. As shown in Fig. 4, when the drive gear 18 rotates in the direction of arrow R3 shown in Fig. 4, the driven gear 19 rotates in the direction of arrow R4 shown in Fig. 4. In this manner, when the drive gear 18 and the driven gear 19 rotate, oil circulates through the oil passage 60 due to a pumping action caused by the meshing of the drive gear 18 and the driven gear 19. Therefore, the oil passage 60 circulates oil due to the pumping action caused by the meshing of the drive gear 18 and the driven gear 19.

[0075] Specifically, when the drive gear 18 and the driven gear 19 rotate, the oil in the gear chamber 24 is discharged to the outer circumferential passage 61 through the discharge passage 63. The oil discharged to the outer circumferential passage 61 is diverted to the first orbital passage 64 and the second orbital passage 65 at the diverging position. The oil flowing through the first orbital passage 64 and the second orbital passage 65 merges at the merging position. At this time, the collision of the oil caused by the merging is mitigated by the buffer protrusion 66. This suppresses the generation of bubbles due to the collision of the oil. Then, the oil is supplied to the gear chamber 24 through the supply passage 62 in a state in which the generation of bubbles in the oil is suppressed. Therefore, the generation of bubbles in the oil in the gear chamber 24 is suppressed.

[0076] Rotation of the drive gear 18 and the driven gear 19 generates a negative pressure that draws oil in the pressure relief passage 80 into the branch passage 85. Therefore, for example, even if oil bubbles generated in the gear chamber 24 flow into the pressure relief passage 80, the oil in the pressure relief passage 80 is drawn into the branch passage 85. Then, the oil drawn into the branch passage 85 flows back from the branch passage 85 into the gear chamber 24. Therefore, oil bubbles generated in the gear chamber 24 are prevented from leaking out of the pressure relief passage 80 to the outside.

[0077] [Effects of the embodiment] The above embodiment can provide the following effects. (1) The oil circulates through the oil passage 60 by the pumping action caused by the meshing of the drive gear 18 and the driven gear 19, so that the drive gear 18 and the driven gear 19 can be well lubricated. When the drive gear 18 and the driven gear 19 rotate, the oil in the gear chamber 24 is discharged to the outer circumferential passage 61 through the discharge passage 63. The oil discharged to the outer circumferential passage 61 is diverted to the first orbital passage 64 and the second orbital passage 65 at the diverging position. The oil flowing through the first orbital passage 64 and the second orbital passage 65 merges at the merging position. At this time, the collision of the oil caused by the merging is mitigated by the buffer protrusion 66. This suppresses the generation of bubbles due to the collision of the oil. Then, the oil is supplied to the gear chamber 24 through the supply passage 62 in a state in which the generation of bubbles in the oil is suppressed. Therefore, the generation of bubbles in the oil in the gear chamber 24 is suppressed. This makes it easier to avoid problems such as oil bubbles generated in the gear chamber 24 leaking to the outside through the pressure relief passage 80, resulting in a corresponding decrease in the amount of oil sealed in the gear chamber 24. As a result, poor lubrication between the drive gear 18 and the driven gear 19 is suppressed, thereby improving the reliability of the fluid machine 10.

[0078] (2) The curved surface 66A has a first curved surface 66a that changes the inflow direction of oil supplied from the first circulating passage 64 to the supply passage 62, and a second curved surface 66b that changes the inflow direction of oil supplied from the second circulating passage 65 to the supply passage 62. With this, the first curved surface 66a can create a flow with less loss in the oil supplied from the first circulating passage 64 to the supply passage 62. In addition, the second curved surface 66b can create a flow with less loss in the oil supplied from the second circulating passage 65 to the supply passage 62.

[0079] (3) The buffer protrusion 66 has a flat surface 66c facing the supply passage 62. This helps to reduce the collision of the oil when the oils flowing through the first and second circulation passages 64 and 65 join at the joining position. This makes it easier to further prevent bubbles from being generated due to the collision of the oils.

[0080] (4) The housing 11 is formed with an oil supply passage 70 that supplies oil from the outer peripheral passage 61 to the first bearing 41 and the second bearing 42. This allows oil to be supplied from the outer peripheral passage 61 to the first bearing 41 and the second bearing 42 via the oil supply passage 70, thereby improving the lubrication of the first bearing 41 and the second bearing 42. Therefore, the reliability of the fluid machine 10 can be further improved.

[0081] (5) The supply passage 62 and the discharge passage 63 are extended to face each other across the meshing portion 28 where the drive gear 18 and the driven gear 19 mesh. This makes it easier for oil to be discharged from the meshing portion 28 between the drive gear 18 and the driven gear 19 to the outer circumferential passage 61 via the discharge passage 63. Also, oil from the outer circumferential passage 61 is easier to be supplied to the meshing portion 28 between the drive gear 18 and the driven gear 19 via the supply passage 62. Therefore, the pumping action caused by the meshing of the drive gear 18 and the driven gear 19 makes it easier for oil to circulate through the oil passage 60, thereby further improving the lubrication of the drive gear 18 and the driven gear 19.

[0082] (6) The gear housing 13 has an upper wall portion 55 and a lower wall portion 56. The upper wall portion 55 is located above the meshing portion 28 and is arranged to fill the space between the drive gear 18 and the driven gear 19 in the gear chamber 24. The lower wall portion 56 is located below the meshing portion 28 and is arranged to fill the space between the drive gear 18 and the driven gear 19 in the gear chamber 24. This makes it difficult for the oil in the gear chamber 24, which is stirred by the rotation of the drive gear 18 and the driven gear 19, to collide in the gear chamber 24. Therefore, it is possible to suppress the generation of oil bubbles in the gear chamber 24.

[0083] (7) The supply passage 62 is located rearward of the meshing portion 28 in the rotational direction of the drive gear 18 and the driven gear 19. The discharge passage 63 is located forward of the meshing portion 28 in the rotational direction of the drive gear 18 and the driven gear 19. This makes it easier for the oil supplied from the supply passage 62 into the gear chamber 24 to be scraped out of the meshing portion 28 by the rotation of the drive gear 18 and the driven gear 19 and to flow into the discharge passage 63. Therefore, the oil is more easily circulated through the oil passage 60 by the pumping action caused by the meshing of the drive gear 18 and the driven gear 19. As a result, the lubrication of the drive gear 18 and the driven gear 19 can be further improved.

[0084] (8) The opening of the branch passage 85 on the gear chamber 24 side is provided to face the teeth 19a of the driven gear 19 so that a negative pressure is generated that draws the oil in the depressurization passage 80 into the branch passage 85 by the rotation of the drive gear 18 and the driven gear 19. With this, even if oil bubbles generated in the gear chamber 24 flow into the depressurization passage 80, the oil in the depressurization passage 80 is drawn into the branch passage 85. Then, the oil drawn into the branch passage 85 flows back into the gear chamber 24 from the branch passage 85. Therefore, the oil bubbles generated in the gear chamber 24 are prevented from leaking out from the depressurization passage 80 to the outside. This makes it easier to avoid a problem in which the oil bubbles generated in the gear chamber 24 leak out from the depressurization passage 80 to the outside, thereby reducing the amount of oil sealed in the gear chamber 24. As a result, poor lubrication between the drive gear 18 and the driven gear 19 is prevented, and the reliability of the fluid machine 10 can be improved.

[0085] (9) The opening of the branch passage 85 faces a portion between the root 19e of the tooth 19a of the rotating driven gear 19 and the tip 19f of the tooth 19a. This makes it easier for a negative pressure to be generated that draws the oil in the pressure relief passage 80 into the branch passage 85 due to the rotation of the drive gear 18 and the driven gear 19. Therefore, even if oil bubbles generated in the gear chamber 24 flow into the pressure relief passage 80, the oil in the pressure relief passage 80 is easily drawn into the branch passage 85. This makes it easier to prevent oil bubbles generated in the gear chamber 24 from leaking out of the pressure relief passage 80 to the outside.

[0086] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0087] In the above embodiment, the buffer protrusion 66 does not have to have the pair of curved surfaces 66A. In the above embodiment, the buffer protrusion 66 does not have to have the flat surface 66c.

[0088] In the above-mentioned embodiment, the fluid machine 10 may have a configuration in which the oil supply passage 70 is not formed in the housing 11 . In the embodiment, the supply passage 62 and the discharge passage 63 do not have to be provided so as to face each other across the meshing portion 28 at which the drive gear 18 and the driven gear 19 mesh. In short, the supply passage 62 may be configured to supply oil from the outer circumferential passage 61 to the gear chamber 24. The discharge passage 63 may be configured to discharge oil from the gear chamber 24 to the outer circumferential passage 61.

[0089] In the above embodiment, the gear housing 13 does not have to have the upper wall portion 55. In the above embodiment, the gear housing 13 does not have to have the bottom wall portion 56. ○ In an embodiment, the supply passage 62 may be located forward of the meshing portion 28 in the rotational direction of the drive gear 18 and the driven gear 19, and the discharge passage 63 may be located rearward of the meshing portion 28 in the rotational direction of the drive gear 18 and the driven gear 19.

[0090] In the above embodiment, the opening of the branch passage 85 on the gear chamber 24 side may be disposed opposite the teeth of the drive gear 18 . In the embodiment, the opening of the branch passage 85 on the gear chamber 24 side may be provided to face the teeth of the drive gear 18 and the teeth 19a of the driven gear 19. In short, it is only necessary that the opening of the branch passage 85 on the gear chamber 24 side is provided to face the teeth of at least one of the drive gear 18 and the driven gear 19 so that a negative pressure is generated that draws the oil in the pressure relief passage 80 into the branch passage 85 by the rotation of the drive gear 18 and the driven gear 19.

[0091] In an embodiment, the opening of the branch passage 85 may face a portion between the root and tip of the teeth of the rotating drive gear 18 . In the embodiment, the opening of the branch passage 85 may face a portion between a root and a tip of a tooth of the rotating drive gear 18, and a portion between a root 19e of a tooth 19a of the rotating driven gear 19 and a tip 19f of the tooth 19a. In short, it is preferable that the opening of the branch passage 85 faces a portion between a root and a tip of a tooth of at least one of the rotating drive gear 18 and the driven gear 19.

[0092] In the above embodiment, the opening of the branch passage 85 may face the root 19 e of the tooth 19 a of the rotating driven gear 19 . In the above embodiment, the opening of the branch passage 85 may face the tip 19 f of the tooth 19 a of the rotating driven gear 19 .

[0093] In the above embodiment, the housing 11 does not necessarily have to include the branch passage 85. In the above-described embodiment, the drive rotor 20 and the driven rotor 21 may have, for example, a trilobe shape or a quadrilobe shape in a cross section perpendicular to the rotational axis direction of the first rotating shaft 16 and the second rotating shaft 17.

[0094] In the above-mentioned embodiment, the drive rotor 20 and the driven rotor 21 may have, for example, a helical shape. In the embodiment, the fluid machine 10 does not have to be a hydrogen pump for a fuel cell that supplies hydrogen to a fuel cell that generates electricity by chemically reacting hydrogen, which is a fuel gas, with oxygen contained in the air, which is an oxidant gas, and may be used for other purposes. [Explanation of symbols]

[0095] Reference Signs List: 10...fluid machine, 11...housing, 16...first rotating shaft, 17...second rotating shaft, 18...drive gear, 19...driven gear, 24...gear chamber, 28...meshing portion, 29...partition wall, 41...first bearing, 42...second bearing, 60...oil passage, 61...outer peripheral passage, 62...supply passage, 63...discharge passage, 64...first circumferential passage, 65...second circumferential passage, 66...buffering protrusion, 66A...curved surface, 66a...first curved surface, 66b...second curved surface, 66c...flat surface, 70...oil supply passage, 80...pressure relief passage.

Claims

1. A cylindrical housing; a first rotating shaft and a second rotating shaft that are rotatably supported in a state that they are arranged parallel to each other within the housing; A drive gear fixed to the first rotating shaft; a driven gear fixed to the second rotating shaft and meshing with the drive gear, The housing includes: a cylindrical partition wall that accommodates the drive gear and the driven gear and defines a gear chamber in which oil is sealed; a pressure relief passage for releasing pressure in the gear chamber to the outside, the partition wall includes an oil passage that circulates the oil by a pumping action caused by meshing of the drive gear and the driven gear, The oil passage is an outer circumferential passage surrounding the gear chamber; a supply passage that communicates the gear chamber with the outer peripheral passage and supplies the oil from the outer peripheral passage to the gear chamber; a discharge passage for discharging the oil from the gear chamber to the outer circumferential passage, The outer circumferential passage is a first circular passage surrounding the drive gear; a second orbital passage surrounding the driven gear; the discharge passage is connected to the first circulation passage and the second circulation passage at a branch position, the supply passage is connected to a joining position of the first circulation passage and the second circulation passage, A fluid machine, characterized in that a buffer convex portion is formed in the outer peripheral passage at the joining position, for buffering collision of oil caused by joining.

2. The cushioning protrusion has a pair of curved surfaces that are curved so as to gradually approach each other, The curved surface is a first curved surface that changes an inflow direction of oil supplied from the first circulation passage to the supply passage; 2. The fluid machine according to claim 1, further comprising: a second curved surface that changes an inflow direction of oil supplied from the second circulation passage to the supply passage.

3. 3. The fluid machine according to claim 1, wherein the buffer protrusion has a flat surface facing the supply passage, and the joining position is defined by at least the flat surface.

4. the first rotating shaft is supported with respect to the housing by a first bearing, the second rotating shaft is supported with respect to the housing by a second bearing, 4. The fluid machine according to claim 1, wherein the housing is formed with an oil supply passage for supplying the oil from the outer circumferential passage to the first bearing and the second bearing.

5. The fluid machine according to any one of claims 1 to 4, characterized in that the supply passage and the discharge passage are extended so as to face each other across a meshing portion where the drive gear and the driven gear mesh.

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