Fluid machine

Abstract

To provide a fluid machine capable of improving durability of an elastic member.SOLUTION: In a hydrogen circulation pump 10, a seal ring 71 is provided between an inner ring 62 of a fourth bearing 61 and a rotating shaft 17 to seal between the inner ring 62 and the rotating shaft 17. The seal ring 71 imparts energizing force to the inner ring 62 and the rotating shaft 17 in a direction in which the inner ring 62 and the rotating shaft 17 are separated from each other in a radial direction of the rotating shaft 17. The seal ring 71 is disposed in an attachment groove 172 formed on the rotating shaft 17. The attachment groove 172 is formed in such a manner that a depth in the radial direction gradually changes. The seal ring 71 is compressed in accordance with the depth of the attachment groove 172.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a fluid machine in which an elastic ring serving as an elastic member is provided between a drive shaft serving as a rotating shaft and an inner ring of a rolling bearing. The fluid machine includes an electric motor that rotates the drive shaft. In the fluid machine, the rolling bearing includes an outer ring, an inner ring, and multiple rolling elements. The outer ring is attached to a casing serving as a housing by an interference fit. The inner ring is attached to the drive shaft by a clearance fit. Multiple rolling elements are provided between the inner ring and the outer ring. The elastic ring serving as an elastic member is provided between the drive shaft and the inner ring and is in elastic contact with the drive shaft and the inner ring. The inner ring rotates integrally with the drive shaft due to the elastic ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-257057 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when a fluid machine operates for a long period of time, its interior becomes hot. In this case, the elastic member is compressed by the rotating shaft and the inner ring in a high-temperature environment. Compression in a high-temperature environment causes the elastic member to wear and become worn. As the elastic member wears, the frictional force applied by the elastic member to the inner ring and the rotating shaft decreases. As a result, there is a risk that the rotating shaft will slip relative to the inner ring. As the rotating shaft slips relative to the inner ring, both the rotating shaft and the inner ring will wear. This wear has an adverse effect on the clearance inside the fluid machine. As a result, there is a demand for improved durability of the elastic member. [Means for solving the problem]

[0005] a rotating shaft inserted into the housing and rotatably supported by a bearing; and an actuating unit that draws in and discharges fluid by rotation of the rotating shaft, wherein the housing defines an actuating chamber that accommodates the actuating unit and is provided with a bearing support that supports the bearing, the bearing comprising an annular inner ring that is clearance-fitted onto the rotating shaft, an annular outer ring that is provided outer than the inner ring and supported by the bearing support, and rolling elements that are provided between the inner ring and the outer ring, wherein an endless groove is formed in a portion of the rotating shaft that overlaps with the inner ring in a radial direction, and the groove is provided with an endless elastic member that is compressed in the radial direction to suppress slippage between the inner ring and the rotating shaft and that separates the inner ring and the rotating shaft in the radial direction, the groove is formed so that the depth of the groove in the radial direction gradually changes, and the elastic member is compressed according to the depth.

[0006] The portion of the elastic member that is housed in the portion where the groove depth becomes shallower along the rotation direction of the rotating shaft is subject to stronger compression by the inner ring and the rotating shaft. In other words, the thickness of this portion in the radial direction of the rotating shaft becomes thinner. Also, the portion of the elastic member that is housed in the portion where the groove depth becomes deeper along the rotation direction of the rotating shaft is subject to weaker compression by the inner ring and the rotating shaft. In other words, the thickness of this portion in the radial direction of the rotating shaft becomes thicker.

[0007] For example, when a fluid machine is operated for a long period of time, the temperature inside the fluid machine increases compared to before operation. In this case, the elastic member is compressed by the rotating shaft and the inner ring in an environment that is hotter than before operation of the fluid machine. The elastic member wears due to compression by the rotating shaft and the inner ring in an environment that is hotter than before operation. The highly compressed portion of the elastic member wears more than the other portions. That is, in the elastic member accommodated in the above-mentioned groove, the shallowest portion of the groove experiences the greatest wear. When the fluid machine is operating, the elastic member moves slightly along the extension direction of the groove due to friction with the inner ring. Then, for example, the portion of the elastic member that was accommodated in the shallowest portion of the groove before the movement moves to a deeper portion, thereby weakening the compression by the rotating shaft and the inner ring. Furthermore, the portion of the elastic member that is accommodated in the shallowest portion of the groove due to the movement is compressed more by the rotating shaft and the inner ring than before the movement.

[0008] In other words, with the above configuration, the portion of the elastic member that is housed in the shallowest groove portion prevents the rotating shaft from slipping relative to the inner ring while wearing away due to friction with the rotating shaft and the inner ring. Furthermore, the portion of the elastic member that is housed in the shallowest groove portion gradually changes in the direction of rotation as the rotating shaft rotates. As a result, the durability of the elastic member in the fluid machine can be improved compared to when the groove depth is uniform around the entire circumference of the rotating shaft.

[0009] In the above-described fluid machine, the groove may have a shallow groove portion that is shallowest in depth and compresses the elastic member most against the inner ring, and a deep groove portion that is deepest in depth and compresses the elastic member least against the inner ring, the depth gradually increasing from the shallow groove portion to the deep groove portion, and the shallow groove portion may be located on the opposite side of the central axis of the rotating shaft from the deep groove portion.

[0010] According to this, the elastic member can apply frictional force to each of the rotating shaft and the inner ring by the portion accommodated in the shallow groove portion until its thickness in the radial direction of the rotating shaft reaches the depth of the shallow groove portion over the entire circumference in the rotational direction of the rotating shaft. Before the rotating shaft starts to move in the rotational direction, the portion of the elastic member that is accommodated in the deep groove portion is the thickest in the radial direction of the rotating shaft. The time required for the thickness of the elastic member in the radial direction of the rotating shaft to reach the depth of the shallow groove portion over the entire circumference in the rotational direction of the rotating shaft increases as the distance between the shallow groove portion and the deep groove portion in the rotational direction increases. Therefore, in a fluid machine, the time until the elastic member wears over the entire circumference in the rotational direction can be longer compared to, for example, a case in which the deep groove portion and the shallow groove portion are adjacent to each other. As a result, the durability of the elastic member in the fluid machine can be improved.

[0011] In the above fluid machine, the radial thickness of the elastic member provided in the deep groove portion may be greater than the depth of the shallow groove portion and equal to or less than the depth of the deep groove portion. According to this, even if the thickness of the elastic member in the deep groove portion is greater than that in the shallow groove portion but equal to or less than that in the deep groove portion, the fluid machinery can achieve a long life of the elastic member in the same way as when the elastic member is thicker than the depth of the deep groove portion. As a result, the fluid machinery can reduce the cost of the elastic member by making the elastic member thinner. [Effects of the Invention]

[0012] According to the present invention, the durability of the elastic member can be improved. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing a hydrogen circulation pump. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the bearing device. [Figure 3] FIG. 3 is a cross-sectional view taken along line 3-3 showing the inner ring, the seal ring, and the rotating shaft. [Figure 4] FIG. 4 is a cross-sectional view taken along line 3-3 showing the inner ring, the seal ring, and the rotating shaft. [Figure 5]FIG. 5 is a cross-sectional view taken along line 3-3 showing the inner ring, the seal ring, and the rotating shaft. [Figure 6] FIG. 6 is a cross-sectional view taken along line 3-3 showing an inner ring, a seal ring, and a rotating shaft in a modified example. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing a bearing device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment in which the fluid machine is embodied as a hydrogen circulation pump will be described below with reference to FIGS. <Hydrogen circulation pump> 1, the hydrogen circulation pump 10 as a fluid machine is a roots pump. The hydrogen circulation pump 10 is a pump that pumps hydrogen as a fluid by sucking in and discharging the hydrogen.

[0015] The hydrogen circulation pump 10 includes a housing 11, a pump section 30 as an operating section, a gear section 40, and an electric motor 50. The hydrogen circulation pump 10 includes a rotating shaft 17, a first bearing 31a, a pair of second bearings 31b, a pair of third bearings 31c, and a pair of fourth bearings 61. The hydrogen circulation pump 10 includes a pair of bearing devices 60 including the fourth bearings 61. The hydrogen circulation pump 10 includes a first seal member 32a, a pair of second seal members 32b, and a pair of third seal members 32c.

[0016] <Housing> The housing 11 includes a first housing member 12, a second housing member 13, a third housing member 14, a fourth housing member 15, and a fifth housing member 16. The housing 11 is formed by assembling the first housing member 12, the second housing member 13, the third housing member 14, the fourth housing member 15, and the fifth housing member 16 together.

[0017] The first housing member 12 includes a first end wall 12a, a first peripheral wall 12b extending cylindrically from the first end wall 12a, and a first bearing support portion 12c protruding from the first end wall 12a into the first housing member 12.

[0018] The second housing member 13 includes a second end wall 13a, a second peripheral wall 13b extending cylindrically from the second end wall 13a, and a pair of second bearing supports 13c provided on the second end wall 13a. The third housing member 14 includes a third end wall 14a, a third peripheral wall 14b extending cylindrically from the third end wall 14a, and a pair of third bearing supports 14c provided on the third end wall 14a.

[0019] The fourth housing member 15 includes a fourth end wall 15a, a boss 15b protruding from the fourth end wall 15a, and a pair of fourth bearing supports 15c provided on the boss 15b as bearing supports.

[0020] The fifth housing member 16 is plate-shaped. The housing 11 defines a motor chamber 12d, a gear chamber 13d, a rotor chamber 25, and a pair of bearing accommodating chambers 26. The motor chamber 12d is defined by a first end wall 12a, a first peripheral wall 12b, and a second end wall 13a. The electric motor 50 is accommodated in the motor chamber 12d. The first bearing support 12c protrudes toward the motor chamber 12d. The first bearing 31a is attached to the inside of the first bearing support 12c. Therefore, the first bearing 31a is supported by the first bearing support 12c.

[0021] The gear chamber 13d is defined by the second end wall 13a, the second peripheral wall 13b, and the third end wall 14a. The gear portion 40 is accommodated in the gear chamber 13d. Each of the pair of second bearing supports 13c opens to the gear chamber 13d. Each of the pair of second bearings 31b is attached to the inside of the second bearing support portion 13c. Each of the pair of second bearings 31b is supported by the second bearing support portion 13c. Each of the pair of second bearings 31b is located between the motor chamber 12d and the gear chamber 13d.

[0022] A rotor chamber 25 serving as a working chamber is defined by the third end wall 14a, the third peripheral wall 14b, and the fourth end wall 15a. The pump section 30 is accommodated in the rotor chamber 25. In other words, the rotor chamber 25 that accommodates the pump section 30 is defined in the housing 11. Each of the pair of third bearing supports 14c opens to the rotor chamber 25 and the gear chamber 13d. Each of the pair of third bearing supports 14c is located between the gear chamber 13d and the rotor chamber 25. Each of the pair of third bearings 31c is attached to the inside of the third bearing support portion 14c. Each of the pair of third bearings 31c is supported by the third bearing support portion 14c.

[0023] Each of the pair of bearing accommodating chambers 26 is defined between the inside of the boss 15b and the fifth housing member 16. Each of the pair of fourth bearings 61 is attached to the inside of the fourth bearing support portion 15c. Each of the pair of fourth bearings 61 is supported by the fourth bearing support portion 15c. Therefore, the housing 11 is provided with first to fourth bearing support portions 12c, 13c, 14c, and 15c that support the first to fourth bearings 31a to 31c, 61. The bearing device 60 is accommodated in the bearing accommodating chamber 26.

[0024] <Rotation axis> The rotating shaft 17 is inserted into the housing 11. The rotating shaft 17 includes a drive shaft 17a and a driven shaft 17b. The drive shaft 17a and the driven shaft 17b are arranged in parallel. The direction in which the central axis L of the drive shaft 17a and the driven shaft 17b extends is defined as the axial direction X of the rotating shaft 17. The drive shaft 17a penetrates the second end wall 13a, the third end wall 14a, and the fourth end wall 15a. The driven shaft 17b penetrates the third end wall 14a and the fourth end wall 15a. The drive shaft 17a is rotatably supported in the housing 11 via the first bearing 31a, the second bearing 31b, the third bearing 31c, and the fourth bearing 61 of the bearing device 60. The driven shaft 17b is rotatably supported in the housing 11 via the second bearing 31b, the third bearing 31c, and the fourth bearing 61 of the bearing device 60. In other words, the rotary shaft 17 is rotatably supported by the housing 11 through the fourth bearing 61 .

[0025] The first seal member 32a is provided on the second end wall 13a. The first seal member 32a seals between the drive shaft 17a and the second end wall 13a. The second seal member 32b is provided on the third end wall 14a. The second seal member 32b seals between each of the drive shaft 17a and the driven shaft 17b and the third end wall 14a. The third seal member 32c is provided on the fourth end wall 15a. The third seal member 32c seals between each of the drive shaft 17a and the driven shaft 17b and the fourth end wall 15a.

[0026] The electric motor 50 rotates the drive shaft 17a. The gear unit 40 includes a drive gear 18 and a driven gear 19. The drive gear 18 is fixed to the drive shaft 17a. The driven gear 19 is fixed to the driven shaft 17b. The driven gear 19 rotates in mesh with the drive gear 18. The driven gear 19 rotates in the opposite direction to the drive shaft 17a due to the drive gear 18 and the driven gear 19.

[0027] <Pump section> The pump section 30 includes a drive rotor 20 and a driven rotor 21. The drive rotor 20 is attached to the drive shaft 17a. The driven rotor 21 is attached to the driven shaft 17b. The driven rotor 21 rotates together with the drive rotor 20. The drive rotor 20 is rotated by the drive gear 18. The driven rotor 21 is rotated by the driven gear 19.

[0028] The rotor chamber 25 has an intake hole (not shown) that draws hydrogen into the rotor chamber 25, and an outlet hole 46 that discharges hydrogen from the rotor chamber 25. The intake hole and the outlet hole 46 are formed in the third peripheral wall 14b. The intake hole is formed in a portion of the third peripheral wall 14b that is opposite the outlet hole 46, with the pump section 30 in between.

[0029] In the hydrogen circulation pump 10, when the pump section 30 operates as a result of the rotation of the drive rotor 20 and the driven rotor 21, hydrogen is drawn in through an inlet hole formed in the third circumferential wall 14b and drawn into the rotor chamber 25. As the pump section 30 operates, the hydrogen drawn into the rotor chamber 25 is discharged from the outlet hole 46 to the outside of the hydrogen circulation pump 10. The drive rotor 20 and the driven rotor 21 rotate due to the rotation of the drive shaft 17a and the driven shaft 17b, which form the rotary shaft 17. In other words, the pump section 30 draws in and discharges hydrogen due to the rotation of the rotary shaft 17.

[0030] <Bearing device> 2, the bearing device 60 includes a fourth bearing 61 and a seal ring 71 as an elastic member. The bearing device 60 rotatably supports the drive shaft 17a and the driven shaft 17b. Since the bearing device 60 supporting the drive shaft 17a and the bearing device 60 supporting the driven shaft 17b have the same configuration, in the following explanation, the bearing device 60 supporting the drive shaft 17a and the bearing device 60 supporting the driven shaft 17b will be described as the bearing device 60 supporting the rotating shaft 17.

[0031] The fourth bearing 61 includes an inner ring 62, an outer ring 63, and a plurality of rolling elements 64. The fourth bearing 61 may include a sealing member 65. The inner ring 62 is clearance-fitted onto the rotating shaft 17. The inner ring 62 is annular. The direction in which the axis of the inner ring 62 extends is defined as the axial direction of the inner ring 62. The inner ring 62 rotates integrally with the rotating shaft 17. The inner ring 62 includes a first end face 62a on one end face in the axial direction and a second end face 62b on the other end face in the axial direction. The first end face 62a faces the third seal member 32c. The second end face 62b faces the fifth housing member 16.

[0032] The outer ring 63 surrounds the inner ring 62. In other words, the outer ring 63 is provided on the outer peripheral side of the inner ring 62. The outer ring 63 is annular. The outer ring 63 is attached to the inner side of the fourth bearing support portion 15c by an interference fit. In other words, the outer ring 63 is supported by the fourth bearing support portion 15c. The outer ring 63 does not rotate.

[0033] The rolling elements 64 are provided between the inner ring 62 and the outer ring 63. The rolling elements 64 are spherical. Therefore, the fourth bearing 61 is a ball bearing. The rolling elements 64 may be rollers, and the fourth bearing 61 may be a roller bearing. The rolling elements 64 are disposed in a space defined between the inner ring 62 and the outer ring 63. Grease is injected into this space. The grease lubricates the spaces between the inner ring 62 and the rolling elements 64 and between the outer ring 63 and the rolling elements 64.

[0034] The sealing members 65 are disposed on both axial ends of the fourth bearing 61. The sealing members 65 are annular. The sealing members 65 close the space between the inner ring 62 and the outer ring 63 from both axial ends of the fourth bearing 61, thereby preventing grease from leaking.

[0035] The portion of the rotating shaft 17 that is supported by the bearing device 60 is referred to as a support shaft portion 171. The support shaft portion 171 is a portion of the rotating shaft 17 that is aligned with the inner ring 62 in the radial direction of the rotating shaft 17. The support shaft portion 171 has a circumferential surface 171a. The circumferential surface 171a is a surface of the rotating shaft 17 that faces the inner ring 62 in the radial direction of the rotating shaft 17.

[0036] <Mounting groove> As shown in Figures 2 and 3, the support shaft portion 171 is formed with a mounting groove 172 as a groove. The mounting groove 172 is recessed from the circumferential surface 171a. That is, the mounting groove 172 is formed in a portion of the rotating shaft 17 that overlaps with the inner ring 62 in the radial direction of the rotating shaft 17. The mounting groove 172 is an endless groove that extends over the entire circumferential direction of the rotating shaft 17. That is, the rotating shaft 17 is formed with an endless mounting groove 172. The mounting groove 172 extends in the circumferential direction of the rotating shaft 17. In other words, the rotating shaft 17 is formed with a mounting groove 172 that extends in a direction perpendicular to the axial direction X in a plan view from the radial direction of the rotating shaft 17.

[0037] The mounting groove 172 is defined by a groove bottom surface 172a and a pair of groove side surfaces 172b. The groove bottom surface 172a is an annular surface located at the tip of a recess in the peripheral surface 171a. Each of the pair of groove side surfaces 172b stands upright from the periphery of the groove bottom surface 172a. Each of the pair of groove side surfaces 172b is an annular surface. Each of the pair of groove side surfaces 172b faces each other in the axial direction X.

[0038] The support shaft portion 171 is made up of a support base portion 173 and an eccentric portion 174. The support base portion 173 is a portion of the support shaft portion 171 that has a peripheral surface 171a. The eccentric portion 174 is a portion of the support shaft portion 171 that has a groove bottom surface 172a as its peripheral surface. The support shaft portion 171 has two support bases 173. The support shaft portion 171 is made up of two support bases 173 with the eccentric portion 174 interposed between them.

[0039] The support base 173 is cylindrical with its axis coincident with the central axis L. The support base 173 extends in the axial direction X. Each of the two support bases 173 has a groove side surface 172b as a surface in the axial direction X. In the support shaft portion 171, the two support bases 173 are aligned so that each of the pair of groove side surfaces 172b is aligned in the axial direction X.

[0040] The eccentric portion 174 is disk-shaped and has a groove bottom surface 172a. The thickness direction of the eccentric portion 174 coincides with the axial direction X. The axis of the eccentric portion 174 is referred to as the eccentric axis LE. The eccentric axis LE is parallel to the central axis L. The diameter of the eccentric portion 174 is smaller than the diameter of the support base 173.

[0041] The depth of the mounting groove 172 is equal to the distance between the groove bottom surface 172a and the circumferential surface 171a in the radial direction of the rotating shaft 17. In other words, the depth of the mounting groove 172 is the difference between the diameter of the support base 173 and the diameter of the eccentric portion 174.

[0042] The eccentric shaft LE is located at a different position from the central axis L in the radial direction of the rotating shaft 17. The eccentric shaft LE is spaced apart from the central axis L in the radial direction of the rotating shaft 17. In other words, when viewed from the axial direction X, the center of the eccentric portion 174 is located at a different position from the center of the support base 173.

[0043] The depth of the mounting groove 172 varies along the direction in which the groove bottom surface 172a extends. In other words, the mounting groove 172 is formed so that the depth in the radial direction of the rotary shaft 17 varies gradually.

[0044] The mounting groove 172 is composed of a deep groove portion 175, a shallow groove portion 176, and two connecting groove portions 177. The deep groove portion 175, the shallow groove portion 176, and the two connecting groove portions 177 are aligned in the direction in which the mounting groove 172 extends. In Fig. 3, the boundary between the deep groove portion 175 and the connecting groove portion 177, and the boundary between the shallow groove portion 176 and the connecting groove portion 177, are each indicated by a two-dot chain line as a groove boundary line M.

[0045] The deep groove portion 175 is a portion of the mounting groove 172 where the distance between the peripheral surface 171a and the groove bottom surface 172a is greater than the shallow groove portion 176 and the connecting groove portion 177. In other words, the mounting groove 172 has the deep groove portion 175 which is the deepest in the radial direction of the rotating shaft 17.

[0046] The shallow groove portion 176 is a portion of the mounting groove 172 where the distance between the peripheral surface 171a and the groove bottom surface 172a is smaller than the deep groove portion 175 and the connecting groove portion 177. In other words, the mounting groove 172 has the shallow groove portion 176, which has the shallowest depth in the radial direction of the rotating shaft 17.

[0047] Each of the two connecting groove portions 177 connects the deep groove portion 175 and the shallow groove portion 176 in the rotation direction of the rotating shaft 17. In other words, each of the two connecting groove portions 177 connects to the deep groove portion 175 at one end and connects to the shallow groove portion 176 at the other end. In each of the two connecting groove portions 177, the distance from the circumferential surface 171a to the groove bottom surface 172a gradually increases from the shallow groove portion 176 toward the deep groove portion 175. In other words, the depth of the mounting groove 172 gradually increases from the shallow groove portion 176 toward the deep groove portion 175.

[0048] The deep groove portion 175 and the shallow groove portion 176 are aligned in the radial direction of the rotating shaft 17 on the support shaft portion 171, with the central axis L between them. In other words, the shallow groove portion 176 is provided on the opposite side of the central axis L from the deep groove portion 175. The two connecting groove portions 177 are aligned in the radial direction of the rotating shaft 17 on the support shaft portion 171, with the central axis L between them.

[0049] <Seal ring> The seal ring 71 is mounted in the mounting groove 172. The seal ring 71 is made of an elastically deformable resin. An example of an elastically deformable resin is rubber. For example, the seal ring 71 is a rubber O-ring. The thickness of the seal ring 71 in the radial direction of the rotating shaft 17 will hereinafter be simply referred to as the thickness of the seal ring 71. Furthermore, if the shape of the seal ring 71 before elastic deformation is defined as the original shape, the thickness of the seal ring 71 in the original shape is constant in the circumferential direction of the seal ring 71. The seal ring 71 is disposed between the inner ring 62 and the rotating shaft 17. The seal ring 71 abuts against the inner ring 62. The seal ring 71 provides a seal between the inner ring 62 and the rotating shaft 17. The seal ring 71 is elastically deformed so as to be compressed between the inner ring 62 and the rotating shaft 17.

[0050] The circumferential direction of the seal ring 71 coincides with the direction in which the mounting groove 172 extends. In other words, the seal ring 71 extends in the rotation direction of the rotary shaft 17. The seal ring 71 is endless.

[0051] The seal ring 71 is compressed in the radial direction of the rotating shaft 17 by the inner ring 62 and the rotating shaft 17. The seal ring 71 is housed in each of the deep groove portion 175, the shallow groove portion 176, and the two connecting groove portions 177, and is compressed in accordance with the depth of the mounting groove 172 at each of them. In other words, the seal ring 71 is compressed in accordance with the depth of the mounting groove 172. More specifically, the seal ring 71 housed in the mounting groove 172 is compressed in the radial direction of the rotating shaft 17 by the inner ring 62 and the rotating shaft 17, so that the cross-sectional shape of the seal ring 71 as seen along the rotational direction of the rotating shaft 17 changes along the rotational direction.

[0052] The seal ring 71 has a first seal portion 71a, a second seal portion 71b, and two third seal portions 71c. In Fig. 3, the boundary between the first seal portion 71a and the third seal portion 71c and the boundary between the second seal portion 71b and the third seal portion 71c are each indicated by a two-dot chain line as a seal portion boundary line S. The first seal portion 71a, the second seal portion 71b, and the two third seal portions 71c are aligned in the circumferential direction of the seal ring 71. In other words, the first seal portion 71a, the second seal portion 71b, and the two third seal portions 71c are aligned in the circumferential direction of the mounting groove 172.

[0053] The first seal portion 71a is the portion of the seal ring 71 that is housed in the deep groove portion 175. The seal ring 71 is least compressed by the rotating shaft 17 and the inner ring 62 at the first seal portion 71a. More specifically, the seal ring 71 is more compressed than the first seal portion 71a in a portion different from the first seal portion 71a. In other words, the deep groove portion 175 compresses the seal ring 71 least. More specifically, the mounting groove 172 compresses the seal ring 71 more at a portion different from the deep groove portion 175 than the deep groove portion 175. The thickness of the seal ring 71 in its original shape is equal to the distance between the groove bottom surface 172a and the inner circumferential surface 62c of the inner ring 62. Therefore, the thickness of the first seal portion 71a is equal to the distance between the groove bottom surface 172a and the inner circumferential surface 62c of the inner ring 62 at the deep groove portion 175. Furthermore, in the original shape of the seal ring 71, the thickness of the first seal portion 71a is greater than the distance between the groove bottom surface 172a in the groove shallow portion 176 and the inner circumferential surface 62c of the inner ring 62.

[0054] The second seal portion 71b is the portion of the seal ring 71 that is housed in the shallow groove portion 176. The seal ring 71 is most compressed by the rotating shaft 17 and the inner ring 62 at the second seal portion 71b. More specifically, the seal ring 71 is more compressed at the second seal portion 71b than at a different portion from the second seal portion 71b. That is, the shallow groove portion 176 most compresses the seal ring 71. More specifically, the mounting groove 172 compresses the seal ring 71 more at the shallow groove portion 176 than at a different portion from the shallow groove portion 176. In the original shape of the seal ring 71, the thickness of the second seal portion 71b is greater than the distance between the groove bottom surface 172a and the inner circumferential surface 62c of the inner ring 62. Therefore, the second seal portion 71b is compressed by the inner ring 62 and the rotating shaft 17 at the shallow groove portion 176. That is, the thickness of the second seal portion 71b in the radial direction of the rotary shaft 17 matches the distance between the groove bottom surface 172a of the shallow groove portion 176 and the inner circumferential surface 62c of the inner ring 62.

[0055] Each of the two third seal portions 71c is a portion of the seal ring 71 that is housed in one of the two connecting grooves 177. In the original shape of the seal ring 71, the thickness of the third seal portion 71c is greater than the distance between the groove bottom surface 172a and the inner circumferential surface 62c of the inner ring 62. Therefore, the third seal portion 71c is compressed by the inner ring 62 and the rotating shaft 17 in the connecting groove 177 in which the third seal portion 71c is housed. In other words, the thickness of the third seal portion 71c in the radial direction of the rotating shaft 17 matches the distance between the groove bottom surface 172a of the connecting groove 177 in which the third seal portion 71c is housed and the inner circumferential surface 62c of the inner ring 62.

[0056] Each of the two third seal portions 71c connects the first seal portion 71a and the second seal portion 71b. One end of each of the two third seal portions 71c is connected to the first seal portion 71a, and the other end is connected to the second seal portion 71b. As described above, in each of the two connecting groove portions 177, the distance from the inner circumferential surface 62c of the inner ring 62 to the groove bottom surface 172a gradually decreases from the first seal portion 71a to the second seal portion 71b. Therefore, in each of the two third seal portions 71c, the thickness of the seal ring 71 in the radial direction of the rotating shaft 17 decreases from the first seal portion 71a to the second seal portion 71b. In other words, the cross-sectional area of ​​the seal ring 71 viewed along the rotational direction of the rotating shaft 17 is largest at the groove deep portion 175. The cross-sectional area of ​​the seal ring 71 as viewed along the direction of rotation of the rotary shaft 17 is smallest at the shallow groove portion 176 .

[0057] The seal ring 71 is pressed against the inner circumferential surface 62c of the inner ring 62 and the groove bottom surface 172a of the mounting groove 172 by a compression reaction force, which is a force that restores the seal ring 71 to its original shape. The compression reaction force of the seal ring 71 applies frictional forces between the seal ring 71 and the groove bottom surface 172a and between the seal ring 71 and the inner circumferential surface 62c. The frictional forces at the points of contact with the seal ring 71 cause the inner ring 62 to rotate integrally with the rotating shaft 17. In other words, the seal ring 71 is compressed in the radial direction of the rotating shaft 17 to suppress slippage between the inner ring 62 and the rotating shaft 17.

[0058] The seal ring 71 is most compressed at the second seal portion 71b by the inner ring 62 and the rotating shaft 17. In other words, the seal ring 71 applies a greater frictional force to the inner ring 62 and the rotating shaft 17 at the second seal portion 71b than at other portions of the seal ring 71.

[0059] The compressive reaction force of the seal ring 71 biases the inner ring 62 and the support shaft portion 171 so as to move them apart in the radial direction of the rotating shaft 17. Therefore, the seal ring 71 applies a biasing force to the inner ring 62 and the rotating shaft 17 in a direction to move them apart in the radial direction of the rotating shaft 17. In other words, the seal ring 71 is provided between the inner ring 62 and the rotating shaft 17, applying a biasing force in a direction to move the inner ring 62 and the rotating shaft 17 apart in the radial direction of the rotating shaft 17 so as to suppress slippage between the inner ring 62 and the rotating shaft 17.

[0060] <Hydrogen Circulation Pump Operation> The drive shaft 17a is rotated by the drive of the electric motor 50. Then, the driven shaft 17b rotates in the opposite direction to the drive shaft 17a via the gear connection between the drive gear 18 and the driven gear 19. This causes the drive rotor 20 and the driven rotor 21 to rotate in opposite directions. With the rotation of the drive rotor 20 and the driven rotor 21, the hydrogen circulation pump 10 draws hydrogen into the rotor chamber 25 through the intake holes formed in the third circumferential wall 14b and discharges hydrogen from the rotor chamber 25 through the discharge holes 46.

[0061] [Operation of the embodiment] The operation of this embodiment will be described below along with the movement of the seal ring 71 that accompanies the operation of the hydrogen circulation pump 10.

[0062] 3, 4, and 5 show the seal ring 71 moving relative to the mounting groove 172 as the hydrogen recirculation pump 10 operates. When the hydrogen recirculation pump 10 rotates the rotary shaft 17, the deep groove portion 175, the shallow groove portion 176, and the two connecting groove portions 177 also rotate about the central axis L. In each of FIGS. 3, 4, and 5, the deep groove portion 175 is illustrated below the shallow groove portion 176 and the two connecting groove portions 177, but this positional relationship is not limited thereto. FIGS. 3, 4, and 5 show a portion of the hydrogen recirculation pump 10 viewed from an angle at which the deep groove portion 175 is at the lowest point of the seal ring 71, showing possible positions of the seal ring 71 as it rotates around the rotary shaft 17.

[0063] The temperature inside the hydrogen circulation pump 10 rises as the electric motor 50 is driven. During operation of the hydrogen circulation pump 10, the seal ring 71 is compressed by the inner ring 62 and the rotating shaft 17 in an environment that is higher in temperature than before operation due to the electric motor 50. Compression in a high-temperature environment causes the seal ring 71 to wear and become worn. This wear is greater in the portion of the seal ring 71 that is more compressed by the inner ring 62 and the rotating shaft 17. This wear is greater in the second seal portion 71b than in the first seal portion 71a and the third seal portion 71c. This wear reduces the compression reaction force in the portion where the wear occurs. This means that during operation of the hydrogen circulation pump 10, the compression reaction force in the second seal portion 71b is greater than in other portions of the seal ring 71. This reduction in the compression reaction force of the seal ring 71 leads to a reduction in the frictional force applied by the seal ring 71 between the rotating shaft 17 and the inner ring 62.

[0064] Due to the reduction in the compression reaction force in the second seal portion 71b, the second seal portion 71b moves slightly from the shallow groove portion 176 toward the connecting groove portion 177 as the rotating shaft 17 rotates. In accordance with this movement, one of the two third seal portions 71c moves from the connecting groove portion 177 toward the shallow groove portion 176, and the other moves from the connecting groove portion 177 toward the deep groove portion 175. In addition, in accordance with this movement, the first seal portion 71a moves from the deep groove portion 175 toward the connecting groove portion 177. In other words, due to the rotation of the rotating shaft 17, the seal ring 71 moves slightly relative to the mounting groove 172 along the direction in which the mounting groove 172 extends.

[0065] The third seal portion 71c that has moved to the shallow groove portion 176 is compressed in the shallow groove portion 176. The third seal portion 71c is compressed more when housed in the shallow groove portion 176 than when housed in the connecting groove portion 177. The first seal portion 71a is compressed in the connecting groove portion 177. The first seal portion 71a is compressed more when housed in the connecting groove portion 177 than when housed in the deep groove portion 175.

[0066] The third seal portion 71c in the shallow groove portion 176 and the first seal portion 71a in the connecting groove portion 177 are each worn due to compression by the inner ring 62 and the rotating shaft 17. This wear reduces the compressive reaction force of the third seal portion 71c and the first seal portion 71a, causing the seal ring 71 to move slightly along the mounting groove 172. This movement of the seal ring 71 is repeated during the operation of the hydrogen circulation pump 10. Figure 4 shows the state in which the seal ring 71 has rotated approximately 90° relative to the mounting groove 172 after this movement has been repeated.

[0067] The above-described relative movement of the seal ring 71 with respect to the mounting groove 172 is repeated until the second seal portion 71b makes one revolution around the mounting groove 172 and reaches the shallow groove portion 176. Fig. 5 shows a state in which the second seal portion 71b has reached the shallow groove portion 176 as a result of this movement of the seal ring 71. Until this state is reached, the seal ring 71 prevents the rotating shaft 17 from slipping relative to the inner ring 62 due to the compression reaction force at the shallow groove portion 176.

[0068] [Effects of this embodiment] The effects of this embodiment will be described. (1) When the hydrogen circulation pump 10 is operating, the portion of the seal ring 71 that is housed in the shallow groove portion 176 gradually changes in the direction of rotation as the rotating shaft 17 rotates. The portion of the seal ring 71 that is housed in the shallow groove portion 176 prevents the rotating shaft 17 from slipping relative to the inner ring 62. The seal ring 71 is compressed by both the rotating shaft 17 and the inner ring 62 and wears due to this compression. This compression of the seal ring 71 is accompanied by wear of the seal ring 71. For example, if the depth of the mounting groove 172 is uniform around the entire circumference of the rotating shaft 17, wear of the seal ring 71 occurs simultaneously all around the entire circumference. Compared to when the depth of the mounting groove 172 is uniform around the entire circumference of the rotating shaft 17, the seal ring 71 can take a longer time to wear out due to wear all around. In other words, the hydrogen circulation pump 10 can improve the durability of the seal ring 71. As a result, the seal ring 71 can apply frictional force to the rotating shaft 17 and the inner ring 62 for a longer period of time than if the depth of the mounting groove 172 were uniform around the entire circumference of the rotating shaft 17. The seal ring 71 can suppress wear on the rotating shaft 17 and the inner ring 62 that occurs when the rotating shaft 17 slides relative to the inner ring 62. The seal ring 71 can suppress adverse effects on clearances in the pump section 30, etc. As a result, the hydrogen circulation pump 10 configured as described above can improve the durability of the seal ring 71.

[0069] (2) The mounting groove 172 has a deep groove portion 175 located farthest from the shallow groove portion 176 in the rotational direction of the rotating shaft 17. The portion of the seal ring 71 housed in the shallow groove portion 176 can apply frictional force to both the rotating shaft 17 and the inner ring 62 until the radial thickness of the seal ring 71 reaches the depth of the shallow groove portion 176 over the entire circumference of the rotating shaft 17. The time required for the radial thickness of the seal ring 71 to reach the depth of the shallow groove portion 176 over the entire circumference increases as the distance between the shallow groove portion 176 and the deep groove portion 175 increases in the rotational direction of the rotating shaft 17. Therefore, in the hydrogen recirculation pump 10, the time until the seal ring 71 wears out over the entire circumference in the rotational direction can be extended compared to, for example, when the deep groove portion 175 and the shallow groove portion 176 are adjacent to each other. In other words, the hydrogen recirculation pump 10 can improve the durability of the seal ring 71. As a result, the seal ring 71 can prevent the rotating shaft 17 from slipping against the inner ring 62 for a longer period of time than when the deep groove portion 175 and the shallow groove portion 176 are adjacent to each other. As a result, the hydrogen circulation pump 10 can have a longer life.

[0070] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0071] The seal ring 71 does not have to be compressed in the deep groove portion 175. For example, the radial thickness of the seal ring 71 in the deep groove portion 175, as viewed in the direction of rotation of the rotary shaft 17, may be greater than the depth of the shallow groove portion 176 but less than the depth of the deep groove portion 175. FIG. 7 shows a case in which the thickness of the seal ring 71 in the deep groove portion 175 is equal to the depth of the deep groove portion 175 from the circumferential surface 171a. Even in this case, the hydrogen circulation pump 10 can achieve a long life, just as in the case in which the first seal portion 71a is thicker than the depth of the deep groove portion 175. As a result, the hydrogen circulation pump 10 can reduce costs associated with the seal ring 71 by making the seal ring 71 thinner.

[0072] The thickness of the seal ring 71 may vary in the circumferential direction in its original shape. For example, the seal ring 71 may have, in its original shape, a first seal portion 71a that is thicker than the depth of the deep groove portion 175. The key is that the seal ring 71 needs to have, in at least a portion in the circumferential direction, a portion that is compressed by the inner ring 62 and the rotating shaft 17 in the deep groove portion 175.

[0073] The mounting groove 172 may have a plurality of deep groove portions 175 and a plurality of shallow groove portions 176. The deep groove portion 175 may be located on the opposite side of the shallow groove portion 176 from the deep groove portion 175 in the radial direction of the rotating shaft 17, with the central axis L interposed therebetween. In other words, the cross-sectional shape of the portion having the groove bottom surface 172a as viewed in the axial direction X does not have to be circular. For example, as shown in FIG. 6 , the portion of the support shaft portion 171 that forms the groove bottom surface 172a may have an elliptical shape whose major axis extends in a direction perpendicular to the axial direction X. In this case, the mounting groove 172 has two deep groove portions 175 and two shallow groove portions 176. The two deep groove portions 175 are arranged side by side in the radial direction of the rotating shaft 17, with the central axis L interposed therebetween. The two shallow groove portions 176 are also arranged side by side in the radial direction of the rotating shaft 17, with the central axis L interposed therebetween.

[0074] The cross-sectional shape of the portion of the support shaft portion 171 that forms the groove bottom surface 172a when viewed in the axial direction X may be any shape other than a circle, such as a square or a triangle. In the eccentric portion 174, the distance from the eccentric axis LE to the groove bottom surface 172a may vary around the eccentric axis LE. For example, the eccentric portion 174 may be a square prism with the eccentric axis LE as its axis.

[0075] In the third bearing 31 c , a seal ring 71 may be provided between the inner ring 62 and the rotary shaft 17 to form the bearing device 60 . The pump unit 30 may be of a type other than the Roots type, such as a screw type or a gear type.

[0076] The fluid machine may be used for purposes other than the hydrogen circulation pump 10 as long as it can pump a fluid. For example, the fluid machine may be a water pump. [Explanation of symbols]

[0077] 10...hydrogen circulation pump as fluid machinery, 11...housing, 15c...fourth bearing support portion as bearing support portion, 17...rotating shaft, 25...rotor chamber as working chamber, 30...pump portion as working portion, 61...fourth bearing as bearing, 62...inner ring, 63...outer ring, 64...rolling element, 71...seal ring as elastic member, 171a...circumferential surface, 172...mounting groove as groove, 175...deep groove portion, 176...shallow groove portion, L...central axis, X...axial direction.

Claims

1. Housing and a rotating shaft that is inserted into the housing and rotatably supported by the housing through a bearing; an actuation unit that draws in and discharges fluid by rotation of the rotary shaft, The housing defines an operating chamber that accommodates the operating portion, and is provided with a bearing support portion that supports the bearing, the bearing is a fluid machine including: an annular inner ring that is clearance-fitted onto the rotating shaft; an annular outer ring that is provided outer peripherally of the inner ring and supported by the bearing support portion; and rolling elements that are provided between the inner ring and the outer ring, an endless groove is formed in a portion of the rotating shaft where the inner ring overlaps with the rotating shaft in a radial direction, an endless elastic member is provided in the groove, the elastic member being compressed in the radial direction to suppress slippage between the inner ring and the rotating shaft and separating the inner ring and the rotating shaft in the radial direction; A fluid machine, characterized in that the groove is formed so that the depth of the groove in the radial direction gradually changes, and the elastic member is compressed in accordance with the depth.

2. The groove is a groove shallow portion that has the shallowest depth and most compresses the elastic member against the inner ring; a groove deep portion that has the deepest depth and compresses the elastic member least against the inner ring, the depth gradually increases from the shallow groove portion to the deep groove portion, The fluid machine according to claim 1, wherein the shallow groove portion is provided on the opposite side of the central axis of the rotary shaft from the deep groove portion.

3. 3. The fluid machine according to claim 2, wherein the radial thickness of the elastic member provided in the deep groove portion is greater than the depth of the shallow groove portion and is equal to or less than the depth of the deep groove portion.

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