Sliding element

Abstract

Provided is a sliding element capable of preventing a sealed fluid from leaking into a leakage-side space irrespective of whether the relative rotation direction is forward rotation or reverse rotation.　The sliding element comprises a pair of sliding members 10, 20 in which sliding surfaces 11, 21 rotate and slide relative to each other. The sliding surface 10 has a plurality of introduction grooves 13, 13' for low-speed rotation that communicate with a space S2 on a sealed-fluid F side. The sliding surface 10 is a sliding element M having dynamic-pressure-generating grooves 12 for high-speed rotation that communicate with a leakage-side space S1, and the sliding surface 11 having the introduction grooves 13, 13' for low-speed rotation is furthermore provided with groove means 14, 15' that are positioned closer to the sealed-fluid F side than the dynamic-pressure generating-grooves 12 and that allow the sealed fluid F to flow between adjacent introduction grooves 13, 13'.

Description

[Technical Field]

[0001] The present invention relates to a sliding element, for example, a sliding element having a pair of sliding members used in a shaft seal or a bearing. [Background technology]

[0002] In rotary machines, mechanical seals, in which the sliding surfaces of a pair of sliding members slide relative to each other, are known as sliding elements for preventing leakage of sealed fluids around a rotating shaft. In recent years, there has been a demand for reducing the energy lost due to sliding, for example, in order to protect the environment. Some mechanical seals have dynamic pressure generating grooves on the sliding surfaces to separate the sliding surfaces.

[0003] For example, the mechanical seal shown in Patent Document 1 has a sliding surface of one sliding member provided with a plurality of introduction grooves communicating with the sealed fluid side and spiral grooves as dynamic pressure generating grooves communicating with the leakage side. The introduction grooves extend radially inward from the sealed fluid side while inclining in the other circumferential direction. The spiral grooves extend radially outward from the leakage side while inclining in the one circumferential direction.

[0004] When the relative rotation speed of the sliding members is low, the introduction groove introduces the sealed fluid between the sliding surfaces. This forms a liquid film between the sliding surfaces, and the introduction groove contributes to improving the lubrication of the pair of sliding surfaces. Furthermore, the spiral groove slightly absorbs gas on the leakage side. This gas prevents the sealed fluid from moving to the leakage side, and the spiral groove contributes to preventing the sealed fluid from leaking to the leakage side.

[0005] On the other hand, when the relative rotational speed of the sliding members is high, the spiral groove that draws in the gas on the leakage side generates a positive pressure at the closed end located on the outer diameter side of the sliding surfaces. This positive pressure slightly separates the sliding surfaces, so the spiral groove can contribute to improving the lubrication of the pair of sliding surfaces. Furthermore, as in the case when the relative rotational speed of the sliding members is low, the spiral groove that draws in the gas between the sliding surfaces can contribute to preventing leakage of the sealed fluid to the leakage side. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 051867 (page 10, Figure 3) Summary of the Invention [Problem to be solved by the invention]

[0007] Some types of rotary machines are capable of switching the direction of rotation depending on the situation. Therefore, there is a demand for a mechanical seal that can accommodate not only forward rotation but also reverse rotation relative to the sliding members. However, in a mechanical seal such as that described in Patent Document 1, when the relative rotation of the sliding members is reverse, the sealed fluid is supplied from the introduction groove between the sliding surfaces to ensure lubrication, but there is a risk that the sealed fluid supplied between the sliding surfaces will flow into the spiral groove and leak into the space on the leakage side.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a sliding element that can prevent the sealed fluid from leaking into the space on the leakage side regardless of the relative rotation direction, whether forward or reverse. [Means for solving the problem]

[0009] In order to solve the above problems, the sliding element of the present invention comprises: A pair of sliding members whose sliding surfaces rotate and slide relative to each other, At least one of the sliding surfaces has a plurality of introduction grooves for low-speed rotation which communicate with a space on the sealed fluid side, At least one of the sliding surfaces is a sliding element having a dynamic pressure generating groove for high-speed rotation that communicates with a space on the leakage side, The sliding surface having the introduction groove for low-speed rotation is further provided with groove means which is arranged on the sealed fluid side of the dynamic pressure generating groove and allows the sealed fluid to flow between adjacent introduction grooves. According to this, when the relative rotation is forward and at a low speed, the introduction groove introduces the sealed fluid between the sliding surfaces, thereby improving the lubrication at the pair of sliding surfaces. When the relative rotation is forward and at a high speed, the dynamic pressure generating groove introduces the leakage-side fluid between the sliding surfaces, thereby improving the lubrication at the pair of sliding surfaces. On the other hand, when the relative rotation is reverse, the introduction groove introduces the sealed fluid between the sliding surfaces, thereby improving the lubrication at the pair of sliding surfaces. Furthermore, the groove means can efficiently cause the sealed fluid that has flowed into one introduction groove to flow into the adjacent introduction groove. In other words, the sealed fluid is recovered in the introduction groove through the groove means. In this way, the groove means can contribute to preventing the sealed fluid from leaking into the leakage-side space through the dynamic pressure generating groove.

[0010] The groove means may include a first groove extending from the introduction groove and a second groove extending from the introduction groove in an opposite direction to the first groove. This generates a positive pressure in the first groove or the second groove depending on the direction of rotation, which can contribute to improving the lubrication of the pair of sliding surfaces.

[0011] The first groove and the second groove may extend in an arc shape. According to this, the first and second grooves formed in an arc shape are less likely to generate dynamic pressure, which is a positive or negative pressure with a radial component, and therefore the first and second grooves make it easier for the sealed fluid to flow from one introduction groove to the adjacent introduction groove.

[0012] An end of the first groove of one of the introduction grooves may be positioned closer to the leakage side than an end of the second groove of an adjacent introduction groove. According to this, when the relative rotation is reverse rotation, the first groove can efficiently recover the sealed fluid that has flowed out from the second groove.

[0013] The first groove of one of the introduction grooves may be disposed so as to partially overlap in the radial direction with the second groove of an adjacent introduction groove. According to this, when the relative rotation is reverse rotation, the first groove can more efficiently recover the sealed fluid that has flowed out from the second groove.

[0014] The introduction groove, the first groove, and the second groove may have the same depth. With this, the flow of the sealed fluid between the introduction groove and the first and second grooves is smooth whether the relative rotation is forward or reverse.

[0015] One of the sliding members has the introduction groove for low-speed rotation, the dynamic pressure generating groove for high-speed rotation, and the groove means. With this, the positions of the introduction groove for low speed rotation, the dynamic pressure generating groove for high speed rotation, and the groove means do not change even during relative rotation, so that the sealed fluid can flow smoothly into the adjacent introduction groove. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention. [Figure 2] 3 is a view of the sliding surface of the rotary seal ring in the first embodiment as viewed from the axial direction. FIG. [Figure 3] 10 is an enlarged view of the sliding surface of the rotary seal ring as viewed from the axial direction in the case where the relative rotation is forward and at a low speed in the first embodiment. FIG. [Figure 4] 10 is an enlarged view of the sliding surface of the rotary seal ring as viewed from the axial direction when the relative rotation is forward and at high speed in the first embodiment. FIG. [Figure 5] 10 is an enlarged view of the sliding surface of the rotary seal ring as viewed from the axial direction when the relative rotation is reverse rotation in the first embodiment. FIG. [Figure 6] FIG. 10 is a view of the sliding surface of the rotary seal ring according to the second embodiment of the present invention, as viewed from the axial direction. [Figure 7] FIG. 11 is a view of the sliding surface of the rotary seal ring according to the third embodiment of the present invention, as viewed from the axial direction. [Figure 8] FIG. 11 is a view of the sliding surface of the rotary seal ring according to the fourth embodiment of the present invention, as viewed from the axial direction. [Figure 9] FIG. 11 is a view of the sliding surface of the rotary seal ring according to the fifth embodiment of the present invention, as viewed from the axial direction. [Figure 10] FIG. 13 is a view of the sliding surface of the rotary seal ring according to the sixth embodiment of the present invention, as viewed from the axial direction. [Figure 11] FIG. 13 is a view of the sliding surface of the rotary seal ring according to the seventh embodiment of the present invention, as viewed from the axial direction. [Figure 12] FIG. 13 is a view of the sliding surface of the rotary seal ring according to the eighth embodiment of the present invention, as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given of an embodiment of the sliding element according to the present invention. [Example]

[0018] A sliding element according to a first embodiment will be described with reference to Fig. 1 to Fig. 5. In this embodiment, a mechanical seal having a pair of rotary seal rings and a stationary seal ring will be used as an example of a sliding element having a pair of sliding members. For ease of explanation, grooves formed on the sliding surface may be indicated by dots in the drawings.

[0019] As shown in FIG. 1, the mechanical seal M of this embodiment is a so-called inside type that prevents the sealed fluid F present in the outer space S2 from leaking into the inner space S1 where the atmosphere A is present.

[0020] In this embodiment, the sealed fluid F is a high-pressure liquid. The atmosphere A is a gas with a lower pressure than the sealed fluid F. That is, the inner diameter side of the seal ring constituting the mechanical seal M is the leakage side (low-pressure side). The outer diameter side is the sealed fluid side (high-pressure side). In the present invention, it is preferable to use a combination that does not cause any problems even if the sealed fluid is mixed with a leakage fluid.

[0021] The mechanical seal M is mainly composed of a rotary seal ring 10 and a stationary seal ring 20. The rotary seal ring 10 is annular and is mounted on the rotary shaft 1 via a sleeve 2 so as to be rotatable together with the rotary shaft 1.

[0022] The stationary seal ring 20 is annular and is provided in a non-rotating state but axially movable state on a seal cover 5 fixed to a housing 4 of the device to which the seal ring 20 is attached.

[0023] The stationary seal ring 20 is biased in the axial direction by the elastic member 7. This allows the sliding surface 11 of the rotary seal ring 10 and the sliding surface 21 of the stationary seal ring 20 to slide closely against each other. The sliding surface 21 of the stationary seal ring 20 is a flat surface, and this flat surface does not have any grooves or the like.

[0024] The rotating seal ring 10 and the stationary seal ring 20 are typically formed from a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but any sliding material used for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, or other sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC consisting of SiC and Si, SiC-TiC, and SiC-TiN. Examples of carbon include a mixture of carbonaceous and graphite materials, resin-molded carbon, and sintered carbon. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), and composite materials are also applicable.

[0025] 2, the rotating seal ring 10 slides relative to the stationary seal ring 20 in a clockwise direction as indicated by the solid arrow, or in a counterclockwise direction as indicated by the dashed arrow. In the following description, the direction of the solid arrow indicates the forward rotation direction of the rotating seal ring 10, which is the mating seal ring, and the direction of the dashed arrow indicates the reverse rotation direction.

[0026] The sliding surface 11 of the rotary seal ring 10 is composed of a plurality of spiral grooves 12 as dynamic pressure generating grooves, a plurality of introduction grooves 13, a plurality of first grooves 14 which are part of the groove means, a plurality of second grooves 15 which are part of the groove means, and a land 16.

[0027] Since the spiral grooves 12 have the same shape, unless necessary, the following description will be given for one spiral groove 12. This also applies to the introduction groove 13, the first groove 14, and the second groove 15.

[0028] 3 may be referred to as one introduction groove 13, and one illustrated on the right side of the first introduction groove 13 on the same page, in other words, one disposed adjacent to the first introduction groove 13 in the clockwise direction, as another introduction groove 13'. Also, they may be referred to as another first groove 14' or another second groove 15' that communicate with the other introduction groove 13'.

[0029] 2 and 3, the spiral grooves 12 extend in an arc shape from the open end 12A toward the outer diameter side while being inclined with a component in the reverse rotation direction. The spiral grooves 12 are also evenly spaced on the inner diameter side of the sliding surface 11.

[0030] The spiral groove 12 has an inner diameter side that is an open end 12A that communicates with the internal space S1, and an outer diameter side that is a closed end 12B that is closed. The depth of the spiral groove 12 is constant in the extension direction.

[0031] The introduction grooves 13 extend in the shape of a parallelogram, inclined in the reverse rotation direction from the opening end 13A toward the inner diameter side. The introduction grooves 13 are equally spaced on the outer diameter side of the sliding surface 11.

[0032] An open end 13A on the outer diameter side of the introduction groove 13 communicates with the external space S2. The inner diameter side of the introduction groove 13 is an inner diameter side wall 13B. The reverse rotation direction side of the introduction groove 13 is a reverse rotation side wall 13C. The forward rotation direction side of the introduction groove 13 is a forward rotation side wall 13D. The depth of the introduction groove 13 is constant in the extension direction.

[0033] Reverse-rotation sidewall 13C extends from the outer diameter side toward the inner diameter side at an incline in the reverse-rotation direction. Further, forward-rotation sidewall 13D is disposed opposite reverse-rotation sidewall 13C and extends substantially parallel thereto.

[0034] The first grooves 14 are arc-shaped grooves that extend from the open end 14A in the reverse rotation direction concentrically with the rotary seal ring 10. The first grooves 14 are equally spaced at the radial center of the sliding surface 11 and on the outer diameter side of the spiral grooves 12.

[0035] The forward rotation direction side of the first groove 14 is an open end 14A that communicates with the inner diameter side end of the reverse rotation side wall 13C of the introduction groove 13. The inner diameter side wall of the first groove 14 is continuous with the inner diameter side wall 13B of the introduction groove 13. In other words, the first groove 14 is formed so as to allow the sealed fluid F to flow between the outer space S2 and the open end 14A and the outer space S2 at a position farthest from the outer space S2 among the grooves 13, 14, and 15 that communicate with the outer space S2. The reverse rotation direction side of the first groove 14 is a closed closed end 14B. The depth of the first groove 14 is constant in the extension direction.

[0036] Because introduction groove 13 and first groove 14 are continuous, for the sake of convenience, opening end 14A of first groove 14 is shown by a two-dot chain line in Figures 3 to 6. The same applies to opening end 15A of second groove 15.

[0037] The second grooves 15 are arc-shaped grooves that extend concentrically with the rotary seal ring 10 from the opening end 15A in the forward rotation direction, i.e., in the opposite direction to the first grooves 14. The second grooves 15 are also equally spaced on the outer diameter side of the first grooves 14.

[0038] The reverse rotation direction side of the second groove 15 is an open end 15A that communicates with the center of the outer diameter side of the forward rotation side wall 13D of the introduction groove 13. The forward rotation direction side of the second groove 15 is a closed end 15B. The depth of the second groove 15 is constant in the extension direction.

[0039] The spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 have substantially the same depth. Therefore, the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 are indicated by dots at the same density in Figures 2 to 5.

[0040] Furthermore, the closed end 15B of one second groove 15 is disposed radially outer than the closed end 14B of the other first groove 14' and overlaps with the circumferential center of the other first groove 14' in the radial direction.

[0041] As a result, the closed end 14B of the other first groove 14' is closer to one introduction groove 13 in the circumferential direction than the closed end 15B of the second groove 15. Also, the closed end 15B of one second groove 15 is closer to the other introduction groove 13' in the circumferential direction than the closed end 14B of the other first groove 14'.

[0042] Furthermore, the portion of the sliding surface 11 other than the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 forms a land 16 having a flat surface arranged in the same plane. The flat surface of the land 16 functions as a sliding surface that essentially slides against the sliding surface 21 of the stationary seal ring 20.

[0043] Next, how the mechanical seal M prevents the sealed fluid F from leaking into the internal space S1 will be described with reference to FIGS.

[0044] First, we will explain the case where the rotation of the rotary seal ring 10 is stopped. The stationary seal ring 20 is biased toward the rotary seal ring 10 by the elastic member 7. Therefore, the sliding surfaces 11 and 21, more specifically, the land 16 of the sliding surface 11 and the sliding surface 21, are in contact with each other.

[0045] As a result, the mechanical seal M prevents the sealed fluid F from leaking from the outer space S2 to the inner space S1.

[0046] On the other hand, the air A flows into the spiral groove 12 from the inner space S1 through the open end 12A.

[0047] On the other hand, the sealed fluid F flows into the introduction groove 13 from the outer space S2 through the opening end 13A. The sealed fluid F also flows into the first groove 14 from the introduction groove 13 through the opening end 14A. Similarly, the sealed fluid F flows into the second groove 15 from the introduction groove 13 through the opening end 15A.

[0048] Next, the operation of the mechanical seal M when the rotary seal ring 10 rotates forward at a low speed will be described.

[0049] A portion of the sealed fluid F flowing into the introduction groove 13 is supplied from the introduction groove 13 to between the sliding surfaces 11, 21. More specifically, the sealed fluid F in the introduction groove 13 is subjected to a shearing force in the rotational direction and is supplied between the sliding surfaces 11, 21. As described above, the sealed fluid F flows into the introduction groove 13 even when the rotary seal ring 10 is stopped. Therefore, when the rotary seal ring 10 starts to rotate, a sufficient amount of the sealed fluid F is supplied between the sliding surfaces 11, 21. Meanwhile, the sealed fluid F is supplied to the introduction groove 13 from the outer space S2 through the open end 13A. Therefore, a sufficient amount of the sealed fluid F is maintained in the introduction groove 13.

[0050] Here, the sealed fluid F between the sliding surfaces 11, 21 flows counterclockwise relative to the sliding surface 11, i.e., in the opposite direction to the rotational direction of the rotary seal ring 10, due to shearing force generated by the relative sliding between the sliding surfaces 11, 21. In the following explanation, this relative fluid flow will be simply referred to as the fluid flow.

[0051] In the first groove 14 (see also the first groove 14' in FIG. 3), the sealed fluid F flows toward the closed end 14B of the first groove 14, as indicated by the solid arrows. At this time, the sealed fluid F flows along the arc-shaped first groove 14, along an arc concentric with the sliding surface 11. As a result, a dynamic pressure having a circumferential component is generated in the first groove 14. In other words, the first groove 14 is less likely to generate a dynamic pressure having a radial component.

[0052] Then, the sealed fluid F flowing along the first groove 14 flows out from the closed end 14B to between the land 16 on the sliding surface 11 and the sliding surface 21, as shown by the black arrow. This generates a positive pressure at the closed end 14B. Note that the positive pressure in this embodiment refers to a relative positive pressure that is higher than the ambient pressure.

[0053] On the other hand, as shown by the black arrow, the sealed fluid F is supplied from the introduction groove 13 through the opening end 14A to the first groove 14. Therefore, a sufficient amount of the sealed fluid F is kept in the first groove 14.

[0054] A small amount of the sealed fluid F in the first groove 14 is supplied between the sliding surfaces 11 and 21 from the opening end 14A side of the closed end 14B of the first groove 14.

[0055] In the second groove 15 (see also the second groove 15' in FIG. 3), the sealed fluid F flows toward the opening end 15A of the second groove 15 as indicated by the black arrow. At this time, the sealed fluid F flows along the arc-shaped second groove 15, along an arc concentric with the sliding surface 11. This makes it difficult for a radial component of dynamic pressure to be generated in the second groove 15.

[0056] The sealed fluid F flowing along the second groove 15 flows into the introduction groove 13 through the open end 15A as shown by the black arrow.

[0057] On the other hand, a negative pressure is generated at the closed end 15B of the second groove 15. As a result, as shown by the black arrow, a part of the sealed fluid F between the land 16 on the sliding surface 11 and the sliding surface 21 flows into the second groove 15 from the closed end 15B. Therefore, a sufficient amount of the sealed fluid F is maintained in the second groove 15. Note that the negative pressure in this embodiment refers to a relative negative pressure that is lower than the ambient pressure.

[0058] A small amount of the sealed fluid F in the second groove 15 is supplied between the sliding surfaces 11 and 21 from the open end 15A side of the closed end 15B of the second groove 15.

[0059] As described above, in addition to the supply of the sealed fluid F from the introduction groove 13, the sealed fluid F is also supplied from the first groove 14 and the second groove 15 to between the sliding surfaces 11 and 21. Therefore, compared to the configuration having only the introduction groove 13 as in Patent Document 1, the efficiency of forming a liquid film is higher.

[0060] Furthermore, since a positive pressure is generated at the closed end 14B of the first groove 14, the mechanical seal M can more easily introduce the sealed fluid F between the sliding surfaces 11 and 21. On the other hand, since a negative pressure is generated at the closed end 15B of the second groove 15, the mechanical seal M prevents the sliding surfaces 11 and 21 from separating excessively.

[0061] Furthermore, the closed end 14B of the other first groove 14' is disposed close to the one introduction groove 13. Therefore, the sealed fluid F supplied between the sliding surfaces 11, 21 from the closed end 14B moves a small distance in the radial direction. As a result, the sealed fluid F flows into the one introduction groove 13 located downstream in the flow direction. This allows the other first groove 14' to efficiently collect the sealed fluid F into the one introduction groove 13.

[0062] Moreover, the introduction groove 13 is inclined in the reverse rotation direction from the outer diameter side toward the inner diameter side, so that the sealed fluid F, which tries to move in the reverse rotation direction from the open end 13A side, can be easily guided by the reverse rotation side wall 13C into the first groove 14. As a result, a stable positive pressure is generated at the closed end 14B.

[0063] Furthermore, most of the sealed fluid F that has flowed into the introduction groove 13 through the open end 15A of the second groove 15 flows into the first groove 14 or is returned to the external space S2 from the open end 13A of the introduction groove 13. This makes it difficult for the sealed fluid F to stagnate in the second groove 15. As a result, a stable negative pressure is generated at the closed end 15B.

[0064] Additionally, in the inside type, the sealed fluid F, which has a larger specific gravity than the atmosphere A, is easily pushed out into the outer space S2 by centrifugal force. Therefore, the second groove 15 arranged on the outer diameter side can easily collect the sealed fluid F supplied between the sliding surfaces 11 and 21.

[0065] On the other hand, in the spiral groove 12, as shown by the white arrow, the atmosphere A moves to the closed end 12B, generating a positive pressure at the closed end 12B. As a result, the atmosphere A flows between the sliding surfaces 11 and 21, and the sealed fluid F near the spiral groove 12 is returned to the outer diameter side.

[0066] As a result, as shown schematically by the two-dot chain line in FIG. 3, a liquid film is formed on the outer diameter side of the circumferential region along the closed end 12B of each spiral groove 12, and a gas film is formed on the inner diameter side.

[0067] As described above, when the rotary seal ring 10 rotates at a low speed, the mechanical seal M prevents the sealed fluid F from leaking into the internal space S1. In addition, the mechanical seal M ensures lubrication between the sliding surfaces 11, 21, and can suppress wear between the sliding surfaces 11, 21.

[0068] Next, we will explain how the mechanical seal M prevents leakage of the sealed fluid F into the internal space S1 when the rotary seal ring 10 is rotating forward at high speed. Note that explanations that overlap with those for low-speed rotation will be omitted or simplified.

[0069] 4, a higher positive pressure is generated at the closed end 12B of the spiral groove 12 than when rotating at the above-mentioned low speed. As a result, as shown by the white arrow, the air A supplied between the sliding surfaces 11 and 21 is supplied closer to the outer diameter than when rotating at a low speed. It then flows into the introduction groove 13, the first groove 14, and the second groove 15.

[0070] On the other hand, when rotating forward at a low speed, most of the sealed fluid F supplied between the sliding surfaces 11 and 21 is pushed by the atmosphere A and discharged into the outer space S2.

[0071] Therefore, at the closed end 14B of the first groove 14, the air A flows out between the land 16 on the sliding surface 11 and the sliding surface 21. Similarly, at the closed end 15B of the second groove 15, the air A is collected into the second groove 15. Then, most of the air A collected in the second groove 15 flows into the first groove 14 through the introduction groove 13.

[0072] As a result, as shown schematically by the two-dot chain line in FIG. 4, a liquid film and a gas film are formed with the boundary being the circumferential region along the outer diameter end of each second groove 15.

[0073] As described above, when the rotary seal ring 10 rotates at high speed, the mechanical seal M ensures lubrication between the sliding surfaces 11, 21 by the gas film, and can suppress wear between the sliding surfaces 11, 21.

[0074] Next, the operation when the rotary seal ring 10 is rotating in the reverse direction, particularly the prevention of leakage of the sealed fluid F into the inner space S1, will be described. Note that explanations that overlap with the case of forward rotation will be omitted or simplified.

[0075] As in the case of forward rotation, the sealed fluid F is supplied between the sliding surfaces 11 and 21 from the introduction groove 13, the first groove 14 and the second groove 15.

[0076] As shown in FIG. 5, the sealed fluid F flowing between the sliding surfaces 11 and 21 flows clockwise relative to the sliding surface 11, that is, in the direction opposite to the rotation direction of the rotary seal ring 10.

[0077] In the second groove 15 (see also the second groove 15' in FIG. 5), as indicated by the black arrows, the sealed fluid F flows toward the closed end 15B of the second groove 15. This makes it difficult for a radial component of dynamic pressure to be generated in the second groove 15.

[0078] Then, as shown by the black arrow, the sealed fluid F flowing along the second groove 15 flows out from the closed end 15B to between the land 16 on the sliding surface 11 and the sliding surface 21. This generates a positive pressure at the closed end 15B.

[0079] On the other hand, as shown by the black arrow, the sealed fluid F is supplied from the introduction groove 13 through the opening end 15A to the second groove 15. Therefore, a sufficient amount of the sealed fluid F is kept in the second groove 15.

[0080] In the first groove 14 (see also the first groove 14' in FIG. 5), as indicated by the black arrows, the sealed fluid F flows toward the opening end 14A of the first groove 14. This makes it difficult for a radial component of dynamic pressure to be generated in the first groove 14.

[0081] The sealed fluid F flowing along the first groove 14 flows into the introduction groove 13 through the open end 14A as shown by the black arrow.

[0082] On the other hand, a negative pressure is generated at the closed end 14B of the first groove 14. As a result, as shown by the black arrow, a part of the sealed fluid F between the land 16 on the sliding surface 11 and the sliding surface 21 flows into the first groove 14 from the closed end 14B. Therefore, a sufficient amount of the sealed fluid F is kept in the first groove 14.

[0083] Moreover, the positive pressure generated in the second groove 15 makes it easier for the sealed fluid F in the introduction groove 13 to be supplied to the second groove 15 .

[0084] Therefore, compared to the configuration having only the introduction groove 13 as in Patent Document 1, the amount of sealed fluid F flowing into the inner diameter side wall 13B side of the introduction groove 13 per unit time is smaller. As a result, in the mechanical seal M, the sealed fluid F is less likely to leak into the internal space S1.

[0085] Furthermore, the closed end 15B of one of the second grooves 15 is disposed close to the other introduction groove 13'. Therefore, the sealed fluid F supplied between the sliding surfaces 11 and 21 from the closed end 15B moves only a small amount in the radial direction. As a result, the sealed fluid F flows into the other introduction groove 13' located downstream in the flow direction. This allows the one of the second grooves 15 to efficiently collect the sealed fluid F into the other introduction groove 13'.

[0086] Furthermore, even if the sealed fluid F that has flowed out between the sliding surfaces 11 and 21 from the closed end 15B of one second groove 15 flows toward the inner diameter side, it flows into the other first groove 14'. As a result, the sealed fluid F flows inside the other first groove 14' and is collected into the other introduction groove 13'.

[0087] Similarly, the closed end 14B of the other first groove 14' is disposed at the circumferential center of one second groove 15. Therefore, the other first groove 14' can recover not only the closed end 15B of one second groove 15 but also a wide range of the sealed fluid F supplied between the sliding surfaces 11, 21 from the open end 15A side of the closed end 15B.

[0088] The sealed fluid F supplied between the sliding surfaces 11 and 21 on the inner diameter side of the second groove 15 in one of the introduction grooves 13 is recovered by the negative pressure generated at the closed end 14B of the other first groove 14' located downstream in the flow direction.

[0089] In addition, the closed end 14B of the other first groove 14' is disposed close to the one introduction groove 13. This allows the other first groove 14' to efficiently recover the sealed fluid F that is supplied directly from the one introduction groove 13 to between the sliding surfaces 11, 21.

[0090] Furthermore, the introduction groove 13, which is inclined in the forward rotation direction from the inner diameter side toward the outer diameter side, facilitates the forward rotation side wall 13D to guide the sealed fluid F, which is moving in the forward rotation direction from the first groove 14 side, to the second groove 15. This facilitates the flow of the sealed fluid F from the vicinity of the inner diameter side wall 13B, which is closest to the spiral groove 12, toward the opening end 13A within the introduction groove 13.

[0091] Furthermore, the sealed fluid F that has flowed from the first groove 14 into the introduction groove 13 flows into the second groove 15 or is returned to the external space S2 from the open end 13A of the introduction groove 13. This makes it difficult for the sealed fluid F to stagnate in the first groove 14. As a result, a stable negative pressure is generated at the closed end 14B.

[0092] As described above, when the rotary seal ring 10 rotates in the reverse direction, the mechanical seal M prevents the sealed fluid F from leaking into the internal space S1. Furthermore, the lubrication between the sliding surfaces 11, 21 is ensured, and wear between the sliding surfaces 11, 21 can be suppressed.

[0093] The mechanical seal M of this embodiment, which is configured as described above, can efficiently allow the sealed fluid F that has flowed into one introduction groove 13 to flow into the other introduction groove 13' through the second groove 15 and the other first groove 14', compared to the configuration in which only a land is formed between adjacent introduction grooves as in Patent Document 1.

[0094] As a result, when the rotary seal ring 10 is rotating in the reverse direction, the sealed fluid F supplied between the sliding surfaces 11, 21 is recovered into the other introduction groove 13' through one second groove 15 and the other first groove 14'. In this way, the first grooves 14, 14', ... and the second grooves 15, 15', ... can contribute to preventing the sealed fluid F from leaking into the internal space S1 through the spiral groove 12.

[0095] Moreover, the first grooves 14, 14', ... and the second grooves 15, 15', ... are designed so that dynamic pressure with a radial component is unlikely to occur in either direction of rotation. Moreover, the introduction grooves 13 are arranged in the extension direction of the first grooves 14 and the second grooves 15. Therefore, the other first grooves 14' and one second groove 15 make it easy for the sealed fluid F that has flowed into one introduction groove 13 to flow into one introduction groove 13 or another introduction groove 13'.

[0096] As described above, the introduction groove 13, the first groove 14, and the second groove 15 have approximately the same depth. Therefore, whether the rotation direction of the rotary seal ring 10 is forward or reverse, the flow of the sealed fluid F in the introduction groove 13, the first groove 14, and the second groove 15 is smooth.

[0097] Furthermore, the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 are formed in the rotary seal ring 10. Therefore, the positions of the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 do not change even during relative rotation, so that the sealed fluid F that has flowed into the introduction groove 13 can smoothly flow to the other introduction grooves 13 via the first groove 14 and the second groove 15.

[0098] Compared to a configuration in which the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 are formed in the static seal ring 20, the rotational force of the rotary seal ring 10 acts directly on the sealed fluid F flowing into the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15, making it easier for dynamic pressure to be generated.

[0099] In this embodiment, the spiral groove 12, the introduction groove 13, the first groove 14, and the second groove 15 are described as having substantially the same depth, but this is not limitative and may be changed as appropriate.

[0100] Furthermore, although the spiral groove 12, the introduction groove 13, the first groove 14 and the second groove 15 have been described as having a constant depth in the extension direction, this is not limited thereto, and the depth may change gradually or in a stepped manner. [Example]

[0101] Next, a sliding element according to Example 2 will be described with reference to Fig. 6. Note that a description of the same configuration as in Example 1 will be omitted.

[0102] The sliding surface 111 of the rotary seal ring 110 of the second embodiment is composed of a plurality of spiral grooves 12, a plurality of introduction grooves 113, a plurality of first grooves , a plurality of second grooves 15, and a land .

[0103] The introduction groove 113 is a rectangular groove extending in the radially inward direction from an open end communicating with the outer space S2.

[0104] As a result, whether the rotary seal ring 110 is rotating forward or backward, approximately the same amount of sealed fluid F is supplied to the introduction groove 113 from the outer space S2. Therefore, whether the rotary seal ring 110 is rotating forward or backward, the introduction groove 113 makes it easier to stably ensure lubrication between the sliding surfaces 111, 21.

[0105] In this way, the shape of the guide groove may be changed as appropriate. [Example]

[0106] Next, a sliding element according to Example 3 will be described with reference to Fig. 7. Note that a description of the same configuration as in Examples 1 and 2 will be omitted.

[0107] The sliding surface 211 of the rotary seal ring 210 of this embodiment 3 is composed of a plurality of spiral grooves 12, a plurality of first introduction grooves 217, a plurality of second introduction grooves 218, a plurality of first grooves 14, a plurality of second grooves 15, and a land 216.

[0108] The first introduction groove 217 is a rectangular groove that extends in the radially inward direction from an open end that communicates with the outer space S2. The first introduction groove 217 is also in communication with the first groove .

[0109] The second introduction groove 218 is a rectangular groove that extends radially inward from an open end that communicates with the outer space S2. The second introduction groove 218 is also in communication with the second groove 15.

[0110] As a result, when the rotary seal ring 10 is rotating in the forward direction, the sealed fluid F is supplied to the first groove 14 through the first introduction groove 217. Also, the sealed fluid F is returned from the second groove 15 through the first introduction groove 217 to the outer space S2.

[0111] In this way, the flow direction of the sealed fluid F in the first introduction groove 217 and the flow direction of the sealed fluid F in the second introduction groove 218 can be made different.

[0112] Therefore, the first introduction groove 217 and the second introduction groove 218, which are not connected to each other, can prevent the dynamic pressure generated in one of the first groove 14 and the second groove 15 from interfering with the sealed fluid F in the other.

[0113] In this way, the introduction groove may be divided into two or more grooves. In other words, one introduction groove may be arranged so that only one of the first groove and the second groove communicates with the other introduction groove. [Example]

[0114] Next, a sliding element according to Example 4 will be described with reference to Fig. 8. Note that the description of the same configuration as in Examples 1 to 3 will be omitted.

[0115] The sliding surface 311 of the rotary seal ring 310 of the fourth embodiment is made up of a plurality of spiral grooves 12 , a plurality of introduction grooves 313 , a plurality of first grooves 314 , a plurality of second grooves 315 , and a land 316 .

[0116] The first groove 314 is provided at approximately the same radial position as the second groove 315, i.e., in the extension direction of the second groove 315. Furthermore, the first groove 314 is spaced apart from the second groove 315 in the circumferential direction. In other words, the first groove 314 and the second groove 315 do not overlap in the radial direction.

[0117] As a result, when the rotary seal ring 10 is rotating in the forward direction, a positive pressure is generated in the first groove 314. Therefore, the sealed fluid F in the introduction groove 313 is easily supplied to the first groove 314.

[0118] Furthermore, a negative pressure is generated in the second groove 315. Therefore, the sealed fluid F supplied from the first groove 314 to between the sliding surfaces 311 and 21 is collected in the second groove 315.

[0119] Furthermore, when the rotary seal ring 10 is rotating in the reverse direction, a positive pressure is generated in the second groove 315. Therefore, the sealed fluid F in the introduction groove 313 is easily supplied to the second groove 315.

[0120] Furthermore, a negative pressure is generated in the first groove 314. Therefore, the sealed fluid F supplied from the second groove 315 to between the sliding surfaces 311 and 21 is collected in the first groove 314.

[0121] In this way, the radial positions of the first groove and the second groove may be changed as appropriate. [Example]

[0122] Next, a sliding element according to Example 5 will be described with reference to Fig. 9. Note that the description of the same configuration as in Examples 1 to 4 will be omitted.

[0123] The sliding surface 411 of the rotary seal ring 410 of the fifth embodiment is composed of a plurality of spiral grooves 12 , a plurality of introduction grooves 413 , a plurality of second grooves 415 , and a land 416 .

[0124] The closed end 415B of the second groove 415 extends to the vicinity of the adjacent introduction groove 413 located on the forward rotation direction side.

[0125] As a result, when the rotary seal ring 410 is rotating forward, the sealed fluid F is supplied between the sliding surfaces 411 and 21 from the introduction groove 413 and the second groove 415 .

[0126] Furthermore, when the rotary seal ring 410 is rotating in the reverse direction, the sealed fluid F supplied between the sliding surfaces 411 and 21 from the second groove 415 is recovered in the adjacent introduction groove 413 located downstream in the flow direction.

[0127] Furthermore, the positive pressure generated in the second groove 415 makes it easier for the sealed fluid F in the introduction groove 413 to be supplied to the second groove 415 .

[0128] Thus, the groove means may consist of only the second grooves.Similarly, the groove means may consist of only the first grooves. [Example]

[0129] Next, a sliding element according to Example 6 will be described with reference to Fig. 10. Note that the description of the same configuration as in Examples 1 to 5 will be omitted.

[0130] A sliding surface 511 of a rotary seal ring 510 of this fifth embodiment is composed of a plurality of spiral grooves 12, a plurality of introduction grooves 513, a plurality of third grooves 519 as groove means, and a land 516.

[0131] The third grooves 519 are equally spaced on the outer diameter side of the sliding surface 511, similar to the second grooves 15 in the first embodiment.

[0132] Third groove 519 is a groove that extends circumferentially concentrically with rotary seal ring 510. Third groove 519 has closed end 519A located on the reverse rotation direction side and closed end 519B located on the forward rotation direction side. In other words, third groove 519 is not in communication with introduction groove 513 located on the reverse rotation direction side and introduction groove 513 located on the forward rotation direction side, which are adjacent to each other in the circumferential direction.

[0133] When the rotary seal ring 510 rotates in the forward direction, a positive pressure is generated at the closed end 519A, and a negative pressure is generated at the closed end 519B.

[0134] As a result, the sealed fluid F supplied between the sliding surfaces 511 and 21 from the introduction groove 513 on the forward rotation direction side is recovered at the closed end 519B located downstream in the flow direction. Also, the sealed fluid F flowing out between the sliding surfaces 511 and 21 from the closed end 519A is recovered at the introduction groove 513 on the reverse rotation direction side located downstream in the flow direction.

[0135] Furthermore, when the rotary seal ring 510 is rotating in the reverse direction, negative pressure is generated at the closed end 519A, and positive pressure is generated at the closed end 519B.

[0136] As a result, the sealed fluid F supplied between the sliding surfaces 511 and 21 from the introduction groove 513 on the reverse rotation direction side is recovered at the closed end 519A located downstream in the flow direction. Also, the sealed fluid F supplied between the sliding surfaces 511 and 21 from the closed end 519B is recovered at the introduction groove 513 on the forward rotation direction side located downstream in the flow direction.

[0137] In this way, the groove means need only be configured to assist the introduction groove in recovering the sealed fluid F, and does not have to be in communication with the introduction groove. [Example]

[0138] Next, a sliding element according to Example 7 will be described with reference to Fig. 11. Note that the description of the same configuration as in Examples 1 to 6 will be omitted.

[0139] The sliding surface 611 of the rotary seal ring 610 of this embodiment 7 is composed of a plurality of deep grooves 612 which are part of the dynamic pressure generating groove, a Rayleigh step 632 which is part of the dynamic pressure generating groove, a plurality of introduction grooves 13, a plurality of first grooves 14 which are part of the groove means, a plurality of second grooves 15 which are part of the groove means, and a land 616.

[0140] The deep grooves 612 are rectangular grooves whose open ends on the inner diameter side communicate with the internal space S1 and extend in the outer diameter direction from the open ends. The deep grooves 612 are evenly spaced on the inner diameter side of the sliding surface 611.

[0141] The depth of the deep groove 612 is constant in the extension direction. The depth of the deep groove 612 is deeper than the introduction groove 13, the first groove 14, and the second groove 15. For this reason, the deep groove 612 is indicated by dots at a high density in FIG. 11.

[0142] The Rayleigh steps 632 are arc-shaped grooves that extend from the open end in the reverse rotation direction concentrically with the rotary seal ring 610. The Rayleigh steps 632 are evenly spaced at the radial center of the sliding surface 611 and on the inner diameter side of the first groove 14.

[0143] The forward rotation direction side of the Rayleigh step 632 is an open end that communicates with the reverse rotation direction side of the radially outer end of the deep groove 612. Furthermore, the reverse rotation direction side of the Rayleigh step 632 is a closed end.

[0144] The Rayleigh step 632 has a constant depth in the extension direction. The Rayleigh step 632 is shallower than the introduction groove 13, the first groove 14, and the second groove 15. For this reason, the Rayleigh step 632 is indicated by dots at a low density in FIG. 11 .

[0145] As a result, when the rotary seal ring 610 rotates forward, the atmosphere A in the Rayleigh step 632 moves toward the closed end and flows out from the closed end between the sliding surfaces 611 and 21, generating a positive pressure.

[0146] Furthermore, the deep groove 612 always stores the atmosphere A. This allows the atmosphere A to stably flow into the Rayleigh step 632. Therefore, the Rayleigh step 632 can stably generate a positive pressure.

[0147] In this way, the dynamic pressure generating grooves are not limited to the spiral grooves 12, but may be changed as appropriate.

[0148] The depth of the deep groove 612 and the Rayleigh step 632 may be changed as appropriate. [Example]

[0149] Next, a sliding element according to Example 8 will be described with reference to Fig. 12. Note that the description of the same configuration as in Examples 1 to 7 will be omitted.

[0150] The mechanical seal of the eighth embodiment is of the so-called outside type, in which the sealed fluid F exists in the inner space S11 and the atmosphere A exists in the outer space S12.

[0151] The sliding surface 711 of the rotary seal ring 710 is made up of a plurality of spiral grooves 712 , a plurality of introduction grooves 713 , a plurality of first grooves 714 , a plurality of second grooves 715 , and a land 716 .

[0152] The spiral grooves 712 are evenly spaced on the outer diameter side of the sliding surface 711. The open ends on the outer diameter side of the spiral grooves 712 communicate with the external space S12, and extend in the reverse rotation direction from the communicating point.

[0153] The introduction grooves 713 are evenly spaced on the inner diameter side of the sliding surface 711. The introduction grooves 713 have their open ends on the inner diameter side communicate with the internal space S11, and extend in the reverse rotation direction and in the outer diameter direction based on this communication point.

[0154] The first grooves 714 are equally spaced at the radial center of the sliding surface 711 and on the inner diameter side of the spiral groove 712. The open end of the first groove 714 on the forward rotation direction side communicates with the inner diameter end of the reverse rotation side wall of the introduction groove 713, and extends in the reverse rotation direction based on this communication point.

[0155] The second grooves 715 are evenly spaced on the inner diameter side of the sliding surface 711. The open ends of the second grooves 715 located on the reverse rotation direction side communicate with the center of the inner diameter side of the forward rotation side wall of the introduction groove 713, and extend in the forward rotation direction from that communicating point.

[0156] When the rotary seal ring 710 rotates in the forward direction, a positive pressure is generated at the closed end of the spiral groove 712 .

[0157] The introduction groove 713 introduces the sealed fluid F between the sliding surfaces 711 and 21. A positive pressure is generated at the closed end of the first groove 714. A negative pressure is generated at the closed end of the second groove 715.

[0158] This improves the lubrication of the pair of sliding surfaces 711, 21 whether the relative rotation is forward and at a low speed or forward and at a high speed.

[0159] Furthermore, when the rotary seal ring 710 is rotating in the reverse direction, a negative pressure is generated at the closed end of the first groove 714. Furthermore, a positive pressure is generated at the closed end of the second groove 715.

[0160] As a result, the sealed fluid F is recovered into the introduction groove 713 through the first groove 714 and the second groove 715 .

[0161] In this way, a pair of sliding surfaces having a dynamic pressure generating groove, an introduction groove, and a groove means may be applied to an outside-type mechanical seal.

[0162] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0163] For example, in the first to eighth embodiments, a mechanical seal has been described as an example of the sliding element, but other mechanical seals for general industrial machinery, automobiles, water pumps, etc. may also be used. Furthermore, the sliding element is not limited to a mechanical seal, and may be a plain bearing or other sliding element other than a mechanical seal.

[0164] In addition, in Examples 1 to 8, the dynamic pressure generating grooves, introduction grooves, first grooves, and second grooves are described as being formed in the rotary seal ring, but this is not limiting, and they may also be formed in the stationary seal ring. Also, the dynamic pressure generating grooves may be formed in one of the rotary seal ring and the stationary seal ring, and the introduction grooves, first grooves, and second grooves may be formed in the other of the rotary seal ring and the stationary seal ring.

[0165] The sealed fluid flows relative to the sliding surface of the stationary seal ring in the same direction as the direction of relative rotation. For this reason, in a configuration in which an introduction groove, a first groove, and a second groove are formed in the stationary seal ring, the first groove extends in the direction of forward rotation from the introduction groove, and the second groove formed in the stationary seal ring extends in the direction of reverse rotation from the introduction groove. In other words, in the case of forward relative rotation, the first groove is the groove on the side into which the sealed fluid flows from the introduction groove, and the second groove is the groove on the side into which the sealed fluid flows into the introduction groove.

[0166] In addition, in the first to eighth embodiments, the sealed fluid F is described as a high-pressure liquid, but it is not limited to this and may be a gas or a low-pressure liquid, or may be a mist of a mixture of liquid and gas.

[0167] Furthermore, in the above Examples 1 to 8, the fluid on the leakage side was described as being atmospheric air, which is a low-pressure gas, but it is not limited to this and may be a liquid or a high-pressure gas, or may be a mist-like mixture of liquid and gas.

[0168] Furthermore, in Examples 1 to 8, the first groove and the second groove were described as being configured so that positive or negative pressure is generated at their respective closed ends, but this is not limited thereto, and the groove may be configured so that little or no positive or negative pressure is generated.

[0169] Furthermore, in Examples 1 to 8, the first groove and the second groove are described as being arc-shaped, but this is not limited thereto and they may be linear or polygonal, and their shapes may be changed as appropriate. [Explanation of symbols]

[0170] 10 Rotating seal ring 11 Sliding surface 12 Spiral groove (dynamic pressure generating groove) 13,13' Lead-in groove 14,14' 1st groove (groove means) 15,15' 2nd groove (groove means) 20 Stationary sealing ring 21 Sliding surface 110~710 Rotating seal ring 111~711 Sliding surface 113~713 Introduction groove 217 1st introduction groove 218 2nd introduction groove 314,714 First groove (groove means) 415,715 Second groove (groove means) 519 Third groove (groove means) 612 Deep groove (dynamic pressure generating groove) 632 Rayleigh Step (dynamic pressure generating groove) 712 Spiral groove (dynamic pressure generating groove) A. Atmosphere F Sealed fluid M Mechanical seal S1, S11 internal space (leak side space) S2, S12 Outside space (space on sealed fluid side)

Claims

1. A pair of sliding members whose sliding surfaces rotate and slide relative to each other, At least one of the sliding surfaces has a plurality of introduction grooves communicating with a space on the sealed fluid side, At least one of the sliding surfaces is a sliding element having a dynamic pressure generating groove that communicates with the space on the leakage side and generates positive pressure during forward rotation, the sliding surface having the introduction groove is further provided with groove means which is arranged closer to the sealed fluid than the dynamic pressure generating groove and allows the sealed fluid to flow between adjacent introduction grooves, the groove means includes a first groove extending from the introduction groove and generating a positive pressure during forward rotation, and a second groove extending from the introduction groove in a direction opposite to the first groove and generating a positive pressure during reverse rotation, A sliding element in which an end portion of the first groove of one of the introduction grooves is arranged closer to the leakage side than an end portion of the second groove of an adjacent introduction groove.

2. A sliding element as described in claim 1, wherein the first groove and the second groove extend in an arc shape.

3. The sliding element according to claim 1 or 2, wherein the first groove of one of the introduction grooves is disposed so as to partially overlap the second groove of an adjacent introduction groove in the radial direction.

4. The sliding element according to claim 1 or 2, wherein the guide groove, the first groove, and the second groove have the same depth.

5. 2. The sliding element according to claim 1, wherein one of said sliding members has said introduction groove, said dynamic pressure generating groove, and said groove means.

6. A sliding element as described in claim 1, wherein the introduction groove is provided separately in each of the first groove and the second groove.

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