Sliding member

Abstract

Provided is a sliding member capable of improving lubricity. A sliding member (10, 20) in which a pair of sliding surfaces (11, 21) rotate relative to each other, the sliding member (10, 20) partitioning a sealed fluid space (S1) and a leakage space (S2), at least one of the sliding surfaces (11) having: a fluid recovery groove (14) having a pressure generating section (143a, 144) as a circumferential end, a curved section or a bent section; and a dynamic pressure generation groove (13) extending from the fluid recovery groove (14) toward the leakage side.

Description

Technical Field

[0001] The present invention relates to sliding members that rotate relative to each other. For example, it relates to sliding members used in a shaft seal device for sealing a rotating shaft of a rotating machine in the fields of automobiles, general industrial machinery, or other sealing fields, or sliding members used in bearings of machines in the fields of automobiles, general industrial machinery, or other bearing fields. Background Art

[0002] As a shaft seal device for preventing leakage of a fluid to be sealed, for example, a mechanical seal has a pair of annular sliding members that rotate relative to each other and whose sliding surfaces slide against each other. In such a mechanical seal, in recent years, in order to address environmental measures and the like, it has been desired to reduce the energy lost due to sliding.

[0003] For example, in the mechanical seal shown in Patent Document 1, a plurality of recesses are provided in the circumferential direction on the sliding surface of the stationary seal ring. The recesses are formed in a crank shape having a cavitation formation region and a positive pressure generation region. The cavitation formation region is disposed on the low-pressure fluid side and is formed in a groove shape extending in the circumferential direction. The positive pressure generation region is disposed on the high-pressure fluid side and is formed in a groove shape extending in the circumferential direction. Further, the downstream end in the rotation direction of the cavitation formation region communicates with the upstream end in the rotation direction of the positive pressure generation region.

[0004] As the rotating seal ring rotates, the recesses guide the fluid to be sealed from the upstream side in the rotation direction of the cavitation formation region to the downstream side in the rotation direction of the positive pressure generation region, and a positive pressure is generated at its downstream end. By means of this positive pressure, the opposing sliding surface is lifted, and the fluid to be sealed is introduced between the sliding surfaces. Therefore, the energy lost due to sliding can be reduced. Further, by means of the negative pressure generated at the upstream end in the rotation direction of the cavitation formation region, the recesses can recover the fluid to be sealed that has moved to the low-pressure space side.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 6058018 (pages 7, 8, Figure 4 ) Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the sliding member of Patent Document 1 as described above, the positive pressure generation region of the recess is disposed close to the fluid space to be sealed. Therefore, a part of the fluid to be sealed can be recovered to the high-pressure fluid side. However, the positive pressure generation regions of the recesses are arranged to be scattered in the circumferential direction. As a result, the positive pressure generated between the sliding surfaces becomes uneven in the circumferential direction, and it is difficult to achieve a floating balance. Therefore, the lubricity may be impaired.

[0010] The present invention has been completed in view of such a problem, and an object thereof is to provide a sliding member capable of improving lubricity.

[0011] Means for Solving the Problem

[0012] In order to solve the above problems, a pair of sliding surfaces of the sliding member of the present invention rotate relative to each other, and the sliding member divides between a fluid space to be sealed and a leakage space, wherein at least any one of the sliding surfaces has: a fluid recovery groove having at least one pressure generating portion as a circumferential end portion, a bent portion, or a folded portion; and a hydrodynamic pressure generating groove extending from the fluid recovery groove toward the leakage side.

[0013] Thereby, it is possible to generate a positive pressure at a plurality of positions in the circumferential direction by the pressure generating portion and the hydrodynamic pressure generating groove of the fluid recovery groove, improve the floating balance between the sliding members, and thereby improve lubricity.

[0014] Alternatively, the fluid recovery groove may communicate with the hydrodynamic pressure generating groove.

[0015] Thereby, fluid is supplied from the fluid recovery groove to the hydrodynamic pressure generating groove, so that a positive pressure can be reliably generated in the hydrodynamic pressure generating groove.

[0016] Alternatively, one fluid recovery groove may communicate with a plurality of the hydrodynamic pressure generating grooves in the circumferential direction.

[0017] Thereby, a positive pressure can be reliably generated at a plurality of positions in the circumferential direction.

[0018] Alternatively, the fluid recovery groove may have: a first groove portion extending in the circumferential direction; a second groove portion extending radially from the first groove portion; and a third groove portion extending from the second groove portion to the circumferentially opposite side of the first groove portion, the pressure generating portion being located at the downstream end of the third groove portion, and the hydrodynamic pressure generating groove being communicated with the third groove portion.

[0019] Thereby, it is possible to efficiently generate a positive pressure using the fluid recovered by the fluid recovery groove.

[0020] Alternatively, the first groove portion may be located on the leakage space side with respect to the third groove portion, and the hydrodynamic pressure generating groove overlaps with the first groove portion of the fluid recovery groove adjacent to the hydrodynamic pressure generating groove in the downstream side of the relative rotation in the radial direction, and overlaps with the second groove portion in the circumferential direction.

[0021] Thereby, it is possible to reliably recover the fluid flowing out between the sliding surfaces from the hydrodynamic pressure generating groove using the fluid recovery groove on the downstream side of the relative rotation.

[0022] Alternatively, the upstream end of the first groove portion of the fluid recovery groove may overlap with the curved portion between the first groove portion and the second groove portion of the fluid recovery groove adjacent to the upstream side of the relative rotation in the circumferential direction.

[0023] Thus, the fluid recovery groove can efficiently recover the sealed fluid flowing out between the sliding surfaces from the pressure generating portion of the fluid recovery groove adjacent to the upstream side of the relative rotation.

[0024] Alternatively, the adjacent first groove portions may be arranged on the same circumference.

[0025] Thus, the first groove portion can guide the sealed fluid along the rotation direction, so that the sealed fluid can be recovered without omission in the circumferential direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a longitudinal sectional view showing an example of a mechanical seal according to Embodiment 1 of the present invention.

[0027] Figure 2 is a view of the sliding surface of the stationary seal ring observed axially.

[0028] Figure 3 is Figure 2 a partial enlarged view of

[0029] Figure 4 is a view of the sliding surface of the stationary seal ring according to Embodiment 2 of the present invention observed axially.

[0030] Figure 5 is a view of the sliding surface of the stationary seal ring according to Embodiment 3 of the present invention observed axially.

[0031] Figure 6 is a view of the sliding surface of the stationary seal ring according to Embodiment 4 of the present invention observed axially.

[0032] Figure 7 is a view of the sliding surface of the stationary seal ring according to Embodiment 5 of the present invention observed axially.

[0033] Figure 8 is a view of the sliding surface of the stationary seal ring according to a modification of Embodiment 1 of the present invention observed axially. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, a method for implementing the sliding member of the present invention will be described based on embodiments.

[0035] Embodiment 1

[0036] Refer to Figures 1 to 3 to describe the sliding member of Embodiment 1. In addition, in the present embodiment, an example in which the sliding member is applied to a mechanical seal will be described.

[0037] Further, a fluid F to be sealed as the first fluid exists in the inner space S1 of the mechanical seal, and the atmosphere A as the second fluid exists in the outer space S2. The inner diameter side of the sliding member constituting the mechanical seal is defined as the fluid space side to be sealed (high-pressure side), and the outer diameter side is defined as the leakage space side (low-pressure side) for explanation. For the sake of convenience in explanation, in the drawings, points may sometimes be marked on the grooves formed on the sliding surface and the like.

[0038] Figure 1 The mechanical seal shown seals the fluid F to be sealed that wants to leak from the inner diameter side to the outer diameter side of the sliding surface, and the outer space S2 communicates with the atmosphere A. This is an outer type mechanical seal. In addition, in this embodiment, an example is shown in which the fluid F to be sealed is a high-pressure liquid and the atmosphere A is a gas at a lower pressure than the fluid F to be sealed.

[0039] The mechanical seal mainly consists of an annular stationary seal ring 10 as a sliding member and an annular rotating seal ring 20 as another sliding member. The rotating seal ring 20 is disposed on the rotating shaft 1 via a sleeve 2 so as to be able to rotate together with the rotating shaft 1. The stationary seal ring 10 is disposed on the seal housing 5 in a non-rotating state and in a state capable of moving axially. The seal housing 5 is fixed to the housing 4 of the equipment to be installed. The stationary seal ring 10 is axially biased by an elastic member 7, and the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide while being in close contact with each other. In addition, the sliding surface 21 of the rotating seal ring 20 is a flat surface, and no concave portions such as grooves are provided on this flat surface.

[0040] The stationary seal ring 10 and the rotating seal ring 20 are typically formed by a combination of SiC (hard material) and SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited thereto. Any sliding material can be used as long as it can be used as a sliding material for a mechanical seal. In addition, as SiC, there are materials composed of two or more phases with different compositions, such as sintered bodies using boron, aluminum, carbon, etc. as sintering aids. For example, SiC dispersed with graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, SiC-TiN, etc. As carbon, resin-molded carbon, sintered carbon, etc., which are represented by carbon mixed with carbonaceous and graphite materials, can be used. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), composite materials, etc. can also be used.

[0041] As shown in Figure 2 and Figure 3 As shown, relative to the stationary seal ring 10, the rotating seal ring 20 as the opposing seal ring slides counterclockwise relatively as shown by the solid arrow.

[0042] On the sliding surface 11 of the stationary seal ring 10, a plurality of dynamic pressure grooves 13 as dynamic pressure generating grooves and a plurality of pumping grooves 14 as fluid recovery grooves are provided. In addition, the portion of the sliding surface 11 other than the dynamic pressure grooves 13 and the pumping grooves 14 is a flat land portion 12.

[0043] The pumping grooves 14 are circumferentially and equally arranged on the inner diameter side of the sliding surface 11 (for example, 16 in this embodiment). The first groove portion 141 of the pumping groove 14 described later and the third groove portion 143 of the pumping groove 14 arranged on the relatively rotating upstream side are partially overlapped in the radial direction.

[0044] The pumping groove 14 is composed of a first groove portion 141, a second groove portion 142, and a third groove portion 143. When viewed axially, the pumping groove 14 has a substantially S-shaped configuration.

[0045] Specifically, the first groove portion 141 extends circumferentially from the upstream side in the rotation direction of the rotary seal ring 20 toward the downstream side in the rotation direction, that is, from the relatively rotating upstream side to the downstream side. In addition, the first groove portion 141 may have a circumferential component as long as it has at least a circumferential component, and may also have a radial component. In addition, the radial direction in the present invention means that as long as it includes at least a radial component, similarly, the circumferential direction in the present invention means that as long as it includes at least a circumferential component.

[0046] The end portion 141a of the first groove portion 141 on the upstream side in the rotation direction of the rotary seal ring 20 is closed. The end portion of the first groove portion 141 on the downstream side in the rotation direction of the rotary seal ring 20 communicates with the second groove portion 142.

[0047] In addition, the end portion 141a of the first groove portion 141 overlaps with the bent portion 144 between the first groove portion 141 and the second groove portion 142 of the pumping groove 14 on the upstream side in the rotation direction of the rotary seal ring 20 in the circumferential direction. In addition, in the present invention, the case where they are arranged at overlapping positions when viewed in the circumferential direction is expressed as overlapping in the circumferential direction. Similarly, in the present invention, the case where they are arranged at overlapping positions when viewed in the radial direction is expressed as overlapping in the radial direction. And the bent portion 144 in this embodiment has a bent shape, but is not limited thereto, and may also be a folded shape.

[0048] And each first groove portion 141 is formed in an arc shape with the same curvature and is arranged on the same circumference. And the curvature of each first groove portion 141 is substantially the same as the curvature of the stationary seal ring 10. And by extending each first groove portion 1641 in the circumferential direction, a circle can be drawn. In addition, the first groove portions 141 may not be arranged on the same circumference.

[0049] The second groove portion 142 extends from the end portion on the downstream side in the rotation direction of the rotary seal ring 20 of the first groove portion 141, is inclined toward the downstream side in the rotation direction of the rotary seal ring 20, and extends toward the inner diameter side. The connecting portion between the first groove portion 141 and the second groove portion 142 is gently curved.

[0050] In the present embodiment, the radial component of the second groove portion 142 is larger than the circumferential component. In addition, the second groove portion 142 only needs to have at least a radial component. That is, the circumferential component of the second groove portion 142 is smaller than the circumferential component of the first groove portion 141, and the radial component of the second groove portion 142 is larger than the radial component of the first groove portion 141.

[0051] The third groove portion 143 extends circumferentially from the inner diameter end portion of the second groove portion 142 toward the downstream side in the rotation direction of the rotary seal ring 20. The connecting portion between the second groove portion 142 and the third groove portion 143 is gently curved. In addition, the third groove portion 143 only needs to have at least a circumferential component, and may also have a radial component. That is, the circumferential component of the third groove portion 143 is larger than the circumferential component of the second groove portion 142, and the radial component of the third groove portion 143 is smaller than the radial component of the second groove portion 142. In addition, in the present embodiment, the first groove portion 141 is parallel to the third groove portion 143, but they may not be parallel.

[0052] The end portion 143a of the third groove portion 143 is closed and functions as a pressure generating portion.

[0053] The hydrodynamic groove 13 extends from the third groove portion 143 of the pumping groove 14 toward the outer diameter side and is inclined toward the downstream side in the rotation direction of the rotary seal ring 20, that is, the downstream side of relative rotation, and extends substantially linearly.

[0054] In the present embodiment, two hydrodynamic grooves 13 are provided separately in the circumferential direction with respect to one pumping groove 14. In addition, with respect to the hydrodynamic groove 13, at least one may be provided with respect to one pumping groove 14, and the number can be freely changed.

[0055] The inner diameter end 13a of the hydrodynamic groove 13 communicates with the third groove portion 143, and the outer diameter end 13b as a hydrodynamic generating portion is closed. In addition, the hydrodynamic groove 13 is not limited to being linear when viewed axially, and may also be an arc shape, a Rayleigh step, a spiral groove, a chevron shape, etc.

[0056] The hydrodynamic groove 13 is formed to have the same depth as the pumping groove 14, for example. In addition, the depth of the hydrodynamic groove 13 may also be different from the depth of the pumping groove 14.

[0057] Next, the functions of the hydrodynamic groove 13 and the pumping groove 14 when the stationary seal ring 10 and the rotary seal ring 20 rotate relative to each other will be briefly described.

[0058] As Figure 3As shown, when the rotary seal ring 20 rotates relative to the stationary seal ring 10, the fluid in the hydrodynamic grooves 13 and the pumping grooves 14 moves following the relative rotation of the rotary seal ring 20.

[0059] Specifically, in the pumping groove 14, as Figure 3 shown by the white arrow, the atmosphere A moves from the end 141a of the pumping groove 14 toward the end 143a. Thus, a positive pressure is slightly generated at the end 143a and its vicinity. Also, a positive pressure is slightly generated at the bent portion 144 and its vicinity. That is, the bent portion 144 functions as a pressure generating portion of the pumping groove 14.

[0060] On the other hand, in the hydrodynamic groove 13, as Figure 3 shown by the black arrow, the fluid moves from the inner diameter end 13a of the hydrodynamic groove 13 toward the outer diameter end 13b. Thus, a positive pressure is generated at the outer diameter end 13b and its vicinity. And the fluid is supplied from the pumping groove 14 to the hydrodynamic groove 13 via the inner diameter end 13a.

[0061] A part of the fluid discharged from the outer diameter end 13b of the hydrodynamic groove 13 to between the sliding surfaces 11 and 21 flows into the pumping groove 14 adjacent in the circumferential direction. Specifically, it mainly flows into the vicinity of the first groove portion 141 and the second groove portion 142 of the pumping groove 14.

[0062] A part of the fluid discharged from the end 143a of the pumping groove 14 to between the sliding surfaces 11 and 21 flows into the pumping groove 14 adjacent in the circumferential direction. Specifically, it mainly flows into the vicinity of the second groove portion 142 and the third groove portion 143 of the pumping groove 14.

[0063] And between the sliding surfaces 11 and 21, by means of the positive pressure generated by the hydrodynamic groove 13 and the pumping groove 14, the sliding surfaces 11 and 21 are lifted, and thus the sealed fluid F flows in from the inner space S1. The sealed fluid F that has flowed into the sealed fluid F is recovered into the pumping groove 14. Therefore, leakage of the sealed fluid F to the outer space S2 can be prevented.

[0064] As described above, a positive pressure can be generated at the outer diameter end 13b of the hydrodynamic groove 13 and the end 143a of the pumping groove 14. Thus, the stationary seal ring 10 generates a positive pressure at multiple locations, and the floating balance with the rotary seal ring 20 can be improved, and thus the lubricity can be improved.

[0065] And the pumping groove 14 of the present embodiment has two types of closed ends, i.e., the end 143a of the pumping groove 14 and the outer diameter end 13b of the hydrodynamic groove 13, on its downstream side. Compared with the existing crank-shaped pumping pits, there are more outflow sites, and thus the relative negative pressure is larger. Therefore, compared with the existing pits, the leakage of the sealed fluid F to the outer space S2 side is less.

[0066] Moreover, two dynamic pressure grooves 13 are circumferentially separated from one pumping groove 14. Therefore, the stationary seal ring 10 can reliably generate positive pressure at multiple circumferential positions.

[0067] Moreover, since a plurality of pumping grooves 14 are provided in the circumferential direction, positive pressure can be generated with good balance at multiple circumferential positions of the stationary seal ring 10.

[0068] Moreover, the dynamic pressure groove 13 is provided in the third groove portion 143 on the downstream side of the pumping groove 14. Thereby, the fluid in the third groove portion 143 with high pressure in the pumping groove 14 can be used to efficiently generate positive pressure in the dynamic pressure groove 13.

[0069] Moreover, the dynamic pressure groove 13 extends from the pumping groove 14 to the outer space S2, and the first groove portion 141 of the pumping groove 14 on the downstream side in the rotation direction of the rotary seal ring 20 is arranged on the outer space S2 side of the outer diameter end 13b of the dynamic pressure groove 13. In other words, the outer space S2 side of the outer diameter end 13b of the dynamic pressure groove 13 is covered by the pumping groove 14. Thereby, the fluid flowing out from the outer diameter end 13b of the dynamic pressure groove 13 between the sliding surfaces 11 and 21 can be reliably recovered by the pumping groove 14 on the relatively downstream side in the rotation direction.

[0070] Moreover, the flow of the fluid flowing in the dynamic pressure groove 13 and the pumping groove 14 is formed over the entire circumference of the stationary seal ring 10, so that the sealed fluid F can be prevented from leaking into the outer space S2.

[0071] Moreover, since the end portion 141a of the first groove portion 141 overlaps with the bent portion 144 between the first groove portion 141 and the second groove portion 142 of the pumping groove 14 on the upstream side in the rotation direction of the rotary seal ring 20 in the circumferential direction, the fluid flowing out from the bent portion 144 to between the sliding surfaces 11 and 12 due to the action of positive pressure generated in the bent portion 144 and its vicinity can be efficiently recovered.

[0072] Moreover, since each first groove portion 141 is formed in an arc shape with the same curvature as the sliding surface 11 and is arranged on the same circumference, the first groove portion 141 can guide the sealed fluid F in the rotation direction. And the sealed fluid F flowing out from the bent portion 144 of the pumping groove 14 adjacent to the upstream side in the rotation direction of the rotary seal ring 20 to between the sliding surfaces 11 and 21 also easily moves in the rotation direction. Thereby, the stationary seal ring 10 can recover the sealed fluid F without omission.

[0073] In addition, in this embodiment, the case where the pumping groove 14 has a substantially S-shaped manner with a gentle bend is illustrated. However, for example, it may also be a crank shape with a corner bent. In this case, positive pressure can be more easily generated at the corner and its vicinity compared with the case of the bent shape.

[0074] Further, in the present embodiment, the manner in which the hydrodynamic groove 13 extends from the pumping groove 14 toward the outer space S2 serving as the leakage space is illustrated. However, as long as the hydrodynamic generation portion of the hydrodynamic groove and the pressure generation portion of the pumping groove are provided at different positions, for example, the hydrodynamic groove may also extend toward the sealed fluid space side.

[0075] Further, in the present embodiment, the manner in which the hydrodynamic groove 13 is communicatively provided with the third groove portion 143 of the pumping groove 14 is illustrated. However, it may also be provided in the first groove portion 141 or the second groove portion 142.

[0076] Further, in the present embodiment, the end portion 143a of the pumping groove 14 is closed. However, the end portion 143a of the pumping groove 14 may also communicate with the inner space S1. In this case, as long as the pressure generation portion is provided at a position other than the end portion 143a of the pumping groove 14.

[0077] Further, the shape of the end portion 143a of the pumping groove 14 can be freely changed. For example, the pressure generation portion may be bent in a protruding manner in the extending direction, or may have a pointed shape.

[0078] Further, the shape of the outer diameter end 13b of the hydrodynamic groove 13 can be freely changed. For example, the hydrodynamic generation portion may be bent in a protruding manner in the extending direction, or may have a pointed shape.

[0079] Further, an independent hydrodynamic generation groove may be provided in addition to the hydrodynamic groove 13 of the present embodiment.

[0080] In addition, regarding the pumping groove 14 of the present embodiment, the manner in which the cross section has a rectangular shape is illustrated. However, the cross-sectional shape may be U-shaped, may be semi-circular, or may be triangular, and can be appropriately changed. The same applies to the hydrodynamic groove 13.

[0081] Embodiment 2

[0082] Next, with reference to Figure 4 the sliding member of Embodiment 2 will be described. In addition, the description of the structure that is the same as that of the foregoing Embodiment 1 will be omitted.

[0083] As Figure 4 shown, a plurality of pumping grooves 314 and a plurality of hydrodynamic grooves 313 are provided on the sliding surface 311 of the stationary seal ring 310 of the present Embodiment 2.

[0084] The pumping groove 314 is composed of a first groove portion 341, a second groove portion 342, and a third groove portion 343.

[0085] The second groove portion 342 extends in an arc shape from the end portion on the downstream side in the rotation direction of the rotary seal ring 20 of the first groove portion 341 toward the inner space S1 so as to protrude toward the inner diameter side. Thus, the bent portion 344 of the first groove portion 341 and the second groove portion 342 of the pumping groove 314 is formed as an acute angle as compared with the bent portion 144 of the first embodiment. The bent portion 344 is a bent portion of the pumping groove 314 and functions as a pressure generating portion of the pumping groove 314.

[0086] Thus, in addition to the dynamic pressure groove 313 and the end portion 343a of the third groove portion 343, a positive pressure is also likely to be generated in the vicinity of the bent portion 344.

[0087] Embodiment 3

[0088] Next, refer to Figure 5 The sliding member of the third embodiment will be described. In addition, the description of the structure that is the same as that of the first embodiment described above will be omitted.

[0089] A plurality of pumping grooves 414 and a plurality of dynamic pressure grooves 413 are formed on the sliding surface 411 of the stationary seal ring 410 of the third embodiment.

[0090] The pumping groove 414 communicates with the second groove portion 442 at a position separated from the end portion 441b, which is a pressure generating portion, on the downstream side in the relative rotation of the rotary seal ring 20 of the first groove portion 441 toward the upstream side.

[0091] Thus, in addition to the dynamic pressure groove 413 and the end portion 443a of the third groove portion 443, a positive pressure can be easily generated at the end portion 441b of the first groove portion 441 and in the vicinity thereof. And, another part of the fluid flowing out from the end portion 441b between the sliding surfaces is recovered by the first groove portion 441 of the pumping groove 414 on the downstream side in the relative rotation. And, the pumping groove 414 can more easily guide the sealed fluid F in the first groove portion 441 to the third groove portion 443 as compared with the pumping groove 314 of the second embodiment.

[0092] Embodiment 4

[0093] Next, refer to Figure 6 The sliding member of the fourth embodiment will be described. In addition, the description of the structure that is the same as that of the first embodiment described above will be omitted.

[0094] A plurality of pumping grooves 514 and a plurality of dynamic pressure grooves 513 are formed on the sliding surface 511 of the stationary seal ring 510 of the fourth embodiment.

[0095] The pumping groove 514 is composed of a first bent groove portion 541 and a second bent groove portion 542.

[0096] The first bending groove portion 541 is formed in an arc shape protruding toward the outer diameter side with a substantially constant curvature smaller than the curvature of the bending portion 144 in the first embodiment. The end portion on the downstream side in the rotation direction of the rotary seal ring 20 of the first bending groove portion 541 communicates with the second bending groove portion 542. The end portion 541a on the upstream side in the rotation direction of the rotary seal ring 20 of the first bending groove portion 541 is closed.

[0097] Moreover, the first bending groove portion 541 has a bending portion 541b that extends from the circumferential center thereof toward the second bending groove portion 542 on the inner diameter side and on the downstream side in the rotation direction of the rotary seal ring 20. A positive pressure is slightly generated in the bending portion 541b. In this way, the bending portion 541b functions as a pressure generation portion of the pumping groove 514.

[0098] Accordingly, compared with the pumping groove 14 in the first embodiment, the positive pressure generated in the bending portion 541b of the pumping groove 514 in this embodiment is suppressed, and it is easy to guide the fluid recovered into the first bending groove portion 541 to the second bending groove portion 542.

[0099] The second bending groove portion 542 has a shape that is substantially the same as the shape obtained by flipping the first bending groove portion 541 in the radial direction and in the circumferential direction. The end portion 542a on the downstream side in the rotation direction of the rotary seal ring 20 of the second bending groove portion 542 is closed. The end portion on the upstream side in the rotation direction of the rotary seal ring 20 of the second bending groove portion 542 communicates with the first bending groove portion 541. Moreover, the second bending groove portion 542 communicates with two dynamic pressure grooves 513.

[0100] Moreover, the second bending groove portion 542 has a bending portion 542b that extends from the circumferential center thereof toward the end portion 542a on the outer diameter side and on the downstream side in the rotation direction of the rotary seal ring 20. A positive pressure is slightly generated in the bending portion 542b. In this way, the bending portion 542b functions as a pressure generation portion of the pumping groove 514.

[0101] Moreover, since the end portion 542a of the second bending groove portion 542 extends toward the downstream side and the outer diameter side in the rotation direction, the pumping groove 514 can generate dynamic pressure at a position radially close to the outer diameter end 513b of each dynamic pressure groove 513. In this way, the bending portion 542b functions as a pressure generation portion of the circumferential end portion on the downstream side in the relative rotation direction of the pumping groove 514.

[0102] Embodiment 5

[0103] Next, a sliding member of Embodiment 5 will be described. In addition, redundant structural descriptions of the same structures as those in the first embodiment are omitted. Figure 7

[0104] ​The mechanical seal using the stationary seal ring 210 of Embodiment 5 seals the fluid F to be sealed existing on the outer space S12 side of the sliding surfaces 211 and 21, and is an inner type mechanical seal in which the inner space S11 communicates with the atmosphere A.

[0105] A plurality of pumping grooves 214 and a plurality of hydrodynamic grooves 213 are formed on the sliding surface 211.

[0106] The pumping grooves 214 and the hydrodynamic grooves 213 have a shape obtained by substantially turning over the pumping grooves 14 and the hydrodynamic grooves 13 of the aforementioned Embodiment 1 in the radial direction.

[0107] Thus, as indicated by the solid arrows, by the rotation of the rotating seal ring 20, positive pressure is generated at the end 243a of the pumping groove 214 and its vicinity. Also, positive pressure is generated at the inner diameter end 213a of the hydrodynamic groove 213 and its vicinity.

[0108] In this way, the sliding member of the present invention can also be applied to an environment where the fluid space to be sealed is on the outer diameter side of the sliding surface and the leakage space is on the inner diameter side of the sliding surface.

[0109] As described above, embodiments of the present invention have been described with reference to the drawings, but the specific structure is not limited to these embodiments, and changes and additions within the scope not departing from the gist of the present invention are also included in the present invention.

[0110] For example, in the aforementioned Embodiments 1 to 5, as the sliding member, an automotive mechanical seal has been described as an example, but it can also be other mechanical seals such as those for general industrial machinery. And, not limited to mechanical seals, it can also be a sliding member other than mechanical seals such as a sliding bearing.

[0111] Also, in the aforementioned Embodiments 1 to 5, the case where the fluid to be sealed is a high-pressure liquid has been described, but it is not limited thereto, and it can also be a gas or a low-pressure liquid, or a mist mixture of liquid and gas.

[0112] Also, in the aforementioned Embodiments 1 to 5, the case where the fluid on the leakage space side is the atmosphere as a low-pressure gas has been described, but it is not limited thereto, and it can also be a liquid or a high-pressure gas, or a mist mixture of liquid and gas.

[0113] Also, in the aforementioned Embodiments 1 to 5, the fluid space to be sealed side has been described as the high-pressure side and the leakage space side as the low-pressure side, but it can also be that the fluid space to be sealed side is the low-pressure side and the leakage space side is the high-pressure side, or that the fluid space to be sealed side and the leakage space side have substantially the same pressure.

[0114] Moreover, in the aforementioned Embodiments 1 to 5, the manner in which the dynamic pressure generating groove communicates with the fluid recovery groove has been described, but is not limited thereto. The dynamic pressure generating groove and the fluid recovery groove may also not communicate. For example, as a modification of Embodiment 1, it may also be as Figure 8 shown, where the dynamic pressure generating groove 13A does not communicate with the fluid recovery groove 14A.

[0115] Moreover, in the aforementioned Embodiments 1 to 5, an example in which the dynamic pressure generating groove and the fluid recovery groove are provided in the stationary seal ring has been described, but the dynamic pressure generating groove and the fluid recovery groove may also be provided in the rotating seal ring.

[0116] Reference Numeral Explanation

[0117] 10: Stationary seal ring (sliding member); 11: Sliding surface; 13: Dynamic pressure groove (dynamic pressure generating groove); 13b: Outer diameter end (dynamic pressure generating portion); 14: Pumping groove (fluid recovery groove); 20: Rotating seal ring (sliding member); 21: Sliding surface; 141: First groove portion; 142: Second groove portion; 143: Third groove portion; 143a: End portion (pressure generating portion); 144: Bending portion (pressure generating portion); A: Atmosphere (fluid on the leakage space side); F: Sealed fluid; S1: Inner space (sealed fluid space); S2: Outer space (leakage space).

Claims

1. A sliding member, wherein a pair of sliding surfaces of the sliding member rotate relative to each other, and the sliding member divides between a fluid-sealed space and a leakage space, wherein, at least any one of the sliding surfaces has: a fluid recovery groove having at least one pressure generating portion as a circumferential end portion, a bent portion or a folded portion; and a hydrodynamic pressure generating groove extending from the fluid recovery groove toward the leakage side.

2. The sliding member according to claim 1, wherein, the fluid recovery groove communicates with the hydrodynamic pressure generating groove.

3. The sliding member according to claim 2, wherein, one fluid recovery groove communicates with a plurality of the hydrodynamic pressure generating grooves in the circumferential direction.

4. The sliding member according to claim 1, wherein, the fluid recovery groove has: a first groove portion extending in the circumferential direction; a second groove portion extending radially from the first groove portion; and a third groove portion extending from the second groove portion to the circumferentially opposite side of the first groove portion, the pressure generating portion is located at the downstream end portion of the third groove portion, and the hydrodynamic pressure generating groove is communicated with the third groove portion.

5. The sliding member according to claim 4, wherein, the first groove portion is located on the leakage space side with respect to the third groove portion, the hydrodynamic pressure generating groove overlaps with the first groove portion of the fluid recovery groove adjacent to the fluid recovery groove communicating with the hydrodynamic pressure generating groove in the downstream side of relative rotation in the radial direction, and overlaps with the second groove portion in the circumferential direction.

6. The sliding member according to claim 4, wherein, the upstream end of the first groove portion of the fluid recovery groove overlaps with the bent portion between the first groove portion and the second groove portion of the fluid recovery groove adjacent to the upstream side of relative rotation in the circumferential direction.

7. The sliding member according to claim 4, wherein, adjacent first groove portions are arranged on the same circumference.

Images