Sliding parts

Abstract

Provided is a sliding component that has high sealing performance during relative positive rotation of the sliding component and that enables sufficient lubrication between sliding surfaces during relative reverse rotation.　Provided in at least one sliding component sliding surface are: positive direction dynamic pressure generation grooves 13 that are in communication with a leakage space S2; positive direction fluid introduction / discharge grooves 18 that are separate from a land part of the positive direction dynamic pressure generation grooves 13 and are in communication with a sealed fluid space S1; and reverse direction fluid introduction / discharge grooves 18' that are separate from the land part of the positive direction dynamic pressure generation grooves 13 and are in communication with the sealed fluid space S1. The positive direction dynamic pressure generation grooves 13 are disposed so as to be more distant with respect to the reverse direction fluid introduction / discharge grooves 18' than with respect to the positive direction fluid introduction / discharge grooves 18.

Description

[Technical Field]

[0001] The present invention relates to a sliding part that rotates relative to another sliding part, such as a sliding part used in a shaft sealing device that seals the rotating shaft of a rotating machine in an automobile, general industrial machine, or other sealing field, or a sliding part used in a bearing of a machine in an automobile, general industrial machine, or other bearing field. [Background technology]

[0002] Mechanical seals, for example, are shaft sealing devices that prevent leakage of sealed fluids and are equipped with a pair of annular sliding components that rotate relative to one another and have sliding surfaces that slide against each other. In recent years, there has been a demand for reducing the energy lost due to sliding in such mechanical seals, for environmental reasons.

[0003] For example, the mechanical seal shown in Patent Document 1 has dynamic pressure generating grooves and fluid introduction grooves provided in a stationary seal ring. The dynamic pressure generating grooves have their starting ends connected to the inner space on the leakage side, and extend in an arc shape inclined in the forward rotation direction of the rotary seal ring from the starting end toward the outer diameter side, with multiple grooves evenly spaced circumferentially. The fluid introduction grooves are also composed of a fluid introduction groove portion that communicates with the outer space, and a Rayleigh step that extends circumferentially concentrically with the stationary seal ring from the inner diameter side of the fluid introduction groove portion toward the forward rotation direction of the rotary seal ring. The sealed fluid is present in the outer space, and the atmosphere is present in the inner space.

[0004] When the rotating seal ring is rotating in the forward direction at a low speed, the positive pressure generated at and near the end of the Rayleigh step of the fluid inlet groove separates the sliding surfaces slightly, allowing the sealed fluid to flow in, thereby lubricating the sliding surfaces and suppressing wear between them, and also, the positive pressure generated at the end of the hydrodynamic groove pushes the sealed fluid that has flowed between the sliding surfaces back into the outer space, thereby suppressing leakage of the sealed fluid from between the sliding surfaces into the inner space. Also, when the rotating seal ring is rotating in the forward direction at a high speed, the positive pressure generation capacity of the hydrodynamic groove as a whole is greater than the positive pressure generation capacity of the Rayleigh step as a whole, resulting in gas lubrication.

[0005] The sliding component of Cited Document 1 is configured to enhance lubrication only during forward rotation of the rotating seal ring. However, depending on the environment in which it is used, there are also mechanical seals in which the rotating seal ring rotates in reverse. In such mechanical seals, it is required that the lubrication be enhanced even during reverse rotation of the rotating seal ring. Therefore, it is conceivable to form an inverse Rayleigh step that extends circumferentially concentrically with the stationary seal ring from the inner diameter side of the fluid guide groove portion of the fluid inlet groove toward the reverse rotation direction of the rotating seal ring (see, for example, Patent Document 2). In this way, during reverse rotation of the rotating seal ring, the sealed fluid flowing out from the end of the inverse Rayleigh step between the sliding surfaces lubricates the sliding surfaces, thereby suppressing wear between the sliding surfaces. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO 2016 / 167262 (page 13, Figure 7) [Patent Document 2] WO 2020 / 162348 (page 8, Figure 6) Summary of the Invention [Problem to be solved by the invention]

[0007] However, although Patent Document 2 can improve lubrication in both rotation directions, its sealing performance during forward rotation is insufficient. Therefore, if a fluid inlet groove having an inverted Rayleigh step as in Patent Document 2 is applied to Patent Document 1, the dynamic pressure generating groove acts to push back the sealed fluid, thereby reducing leakage during forward rotation. On the other hand, during reverse rotation, the sealed fluid in the fluid inlet groove, which flows out from the end of the inverted Rayleigh step and its vicinity, is immediately drawn into the dynamic pressure generating groove from the end side, reducing the pressure of the sealed fluid flowing out from the end of the inverted Rayleigh step of the fluid inlet groove and its vicinity, which could result in a risk of not being able to form a gap between the sliding surfaces large enough to allow the sealed fluid to flow in.

[0008] The present invention has been made in light of these problems, and aims to provide a sliding component that has high sealing performance during relative forward rotation of the sliding components, and can sufficiently lubricate the sliding surfaces during relative reverse rotation. [Means for solving the problem]

[0009] In order to solve the above problems, the sliding component of the present invention comprises: A sliding component in which sliding surfaces of a pair of sliding rings rotate relative to each other to separate a sealed fluid space from a leakage space, at least one of the sliding surfaces is provided with a forward dynamic pressure generating groove communicating with the leakage space, a forward fluid lead-in / out groove isolated from the forward dynamic pressure generating groove by a land portion and communicating with the sealed fluid space, and a reverse fluid lead-in / out groove isolated from the forward dynamic pressure generating groove by a land portion and communicating with the sealed fluid space, The forward dynamic pressure generating grooves are arranged more sparsely relative to the backward fluid lead-out grooves than to the forward fluid lead-out grooves. With this, during relative forward rotation of the sliding parts, the interface between the sealed fluid and the fluid in the leakage space, for example, the gas-liquid interface, is located on the sealed fluid space side, resulting in high sealing performance. Also, since the forward direction dynamic pressure generating grooves are sparsely arranged relative to the reverse direction fluid leading inlet / outlet grooves, during relative reverse rotation of the sliding parts, the sealed fluid does not easily flow from the reverse direction fluid leading inlet / outlet groove to the forward direction dynamic pressure generating groove, so that pressure tends to build up at the end of the reverse direction fluid leading inlet / outlet groove and at the land portion nearby, and a gap sufficient to allow the sealed fluid to flow in can be formed between the sliding surfaces, thereby allowing sufficient lubrication of the sliding surfaces.

[0010] The terminal ends of the forward-direction dynamic pressure generating grooves may be arranged more distantly from the terminal ends of the reverse-direction fluid inlet / outlet grooves than from the terminal ends of the forward-direction fluid inlet / outlet grooves. According to this, when positive pressure is generated in the reverse fluid lead-out groove during relative reverse rotation, the negative pressure generated at the end of the forward dynamic pressure generating groove has little effect, and therefore pressure is likely to build up at the end of the reverse fluid lead-out groove and the land nearby.

[0011] The sparse state may be configured such that the forward-direction dynamic pressure generating grooves, which have a smaller total volume than the forward-direction fluid inlet / outlet grooves, are arranged relative to the reverse-direction fluid inlet / outlet grooves. According to this, by arranging a forward dynamic pressure generating groove with a small total volume relative to the reverse fluid lead-out groove, positive pressure can also be generated by this forward dynamic pressure generating groove, thereby reliably generating dynamic pressure during relative forward rotation and reliably preventing leakage of the sealed fluid during relative forward rotation.

[0012] The sparse state may be configured such that the forward direction dynamic pressure generating grooves, which are radially shorter than the forward direction fluid inlet / outlet grooves, are arranged relative to the reverse direction fluid inlet / outlet grooves. According to this, by arranging a radially short forward dynamic pressure generating groove relative to the reverse fluid lead-out groove, positive pressure can also be generated by this forward dynamic pressure generating groove, thereby reliably generating dynamic pressure during relative forward rotation and reliably preventing leakage of the sealed fluid during relative forward rotation.

[0013] A plurality of the sparsely-formed regions may be arranged in the circumferential direction of the sliding surface. With this, pressure is easily generated in the land portions near the reverse fluid lead-out grooves at a plurality of locations in the circumferential direction of the sliding surfaces during relative reverse rotation, and the sliding surfaces can be sufficiently lubricated.

[0014] The forward-direction dynamic pressure generating groove may be a spiral groove extending in an arc shape inclined from a starting end in the radial direction, the forward-direction fluid lead-out groove may have a fluid guide groove portion communicating with the sealed fluid space and a Rayleigh step extending in the relative forward rotation direction, and the reverse-direction fluid lead-out groove may have a fluid guide groove portion communicating with the sealed fluid space and a reverse Rayleigh step extending in the relative reverse rotation direction. With this, since the forward-direction dynamic pressure generating groove is a spiral groove, positive pressure can be efficiently generated at the terminal end by using the fluid, for example, gas, on the leakage space side. Also, since the Rayleigh step and the reverse Rayleigh step extend in the relative forward rotation direction or the relative reverse rotation direction, most of the sealed fluid flows out in the circumferential direction from the terminal end of the Rayleigh step or the terminal end of the reverse Rayleigh step during relative forward rotation or relative reverse rotation, and is therefore less likely to be drawn in from the terminal end of the forward-direction dynamic pressure generating groove.

[0015] The forward direction fluid inlet / outlet groove and the reverse direction fluid inlet / outlet groove may have a substantially T-shape and share the fluid guide groove portion. According to this, in both the relative forward rotation and the relative reverse rotation, in addition to the sealed fluid in the fluid guide groove portion, when a positive pressure is generated on one side, the sealed fluid in the Rayleigh step on the other side can be utilized, and a sufficient amount of sealed fluid can be used to efficiently generate a positive pressure.

[0016] The forward direction fluid inlet / outlet groove may be disposed on the side of the reverse direction fluid inlet / outlet groove in the relative reverse rotation direction. With this, a portion of the sealed fluid that flows into the space between the sliding surfaces from the end of the reverse-direction fluid inlet / outlet groove is sucked in and recovered from the end of the reverse-direction fluid inlet / outlet groove adjacent to it in the direction of rotation, making it less likely to leak into the external space, which is a leakage space.

[0017] The sealed fluid may be gas or liquid, or may be a mist of a mixture of liquid and gas. [Brief explanation of the drawings]

[0018] [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 stationary seal ring in the first embodiment as viewed from the axial direction. FIG. [Figure 3] 3 is an enlarged view of the sliding surface of the stationary seal ring in the first embodiment as viewed from the axial direction. FIG. [Figure 4]FIG. 10 is an explanatory view of the movement of fluid in the dynamic pressure generating grooves and the fluid introduction grooves during forward rotation, as viewed from the axial direction, on the sliding surface of the stationary seal ring in the first embodiment. [Figure 5] 4 is an explanatory view of the movement of fluid in the dynamic pressure generating grooves and the fluid introduction grooves when the sliding surface of the stationary seal ring in the first embodiment is rotated forward or backward, as viewed from the axial direction. FIG. [Figure 6] FIG. 10 is an enlarged view of the sliding surface of the stationary seal ring in the second embodiment of the present invention, as viewed from the axial direction. [Figure 7] FIG. 11 is an enlarged view of the sliding surface of the stationary seal ring according to the third embodiment of the present invention, as viewed from the axial direction. [Figure 8] FIG. 10 is an enlarged view of the sliding surface of the stationary seal ring according to the fourth embodiment of the present invention, as viewed from the axial direction. [Figure 9] FIG. 10 is a view of the sliding surface of the stationary 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 a stationary seal ring according to a 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 stationary seal ring according to the seventh embodiment of the present invention, as viewed from the axial direction. [Figure 12] FIG. 10 is a view of the sliding surface of the stationary seal ring in a modified example of the first embodiment of the present invention, as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sliding element according to an embodiment of the present invention will be described below with reference to the accompanying drawings. [Example]

[0020] A sliding element according to a first embodiment will be described with reference to Figs. 1 to 5. In this embodiment, the sliding element will be described as a mechanical seal. A sealed fluid exists in the inner space of the mechanical seal, and atmospheric air exists in the outer space. The inner diameter side of the sliding element constituting the mechanical seal will be described as the sealed fluid side (high-pressure side), and the outer diameter side as the leakage side (low-pressure side). For ease of explanation, grooves formed on the sliding surface may be indicated by dots in the drawings.

[0021] The automotive mechanical seal shown in Figure 1 is an outside type that seals against a sealed fluid F that would otherwise leak from the inner diameter side to the outer diameter side of the sliding surface, and has an outer space S2 that communicates with the atmosphere A. In this embodiment, the sealed fluid F is a high-pressure liquid, and the atmosphere A is a gas that is at a lower pressure than the sealed fluid F.

[0022] The mechanical seal is primarily composed of a rotating seal ring 20 as another sliding part, and a ring-shaped stationary seal ring 10 as another sliding part. The rotating seal ring 20 is mounted on a rotating shaft 1 via a sleeve 2 so that it can rotate together with the rotating shaft 1. The stationary seal ring 10 is mounted in a non-rotating state but axially movable in a seal cover 5 fixed to a housing 4 of the device to which it is attached. The stationary seal ring 10 is biased in the axial direction by an elastic member 7, so that the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide closely against each other. The sliding surface 21 of the rotating seal ring 20 is flat, and this flat surface does not have any recesses such as grooves.

[0023] The stationary seal ring 10 and the rotating seal ring 20 are typically formed of SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but this is not limiting; 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.

[0024] 2 and 3, the rotating seal ring 20, which is the mating seal ring, slides relative to the stationary seal ring 10 in the counterclockwise direction as indicated by the solid arrow and in the clockwise direction as indicated by the dotted arrow. In the following description, the rotation direction indicated by the solid arrow is the forward rotation direction, and the rotation direction indicated by the dotted arrow is the reverse rotation direction.

[0025] A plurality of hydrodynamic grooves 13 are uniformly arranged in the circumferential direction on the outer diameter side of the sliding surface 11 of the stationary seal ring 10, and a plurality of fluid introduction grooves 16 as fluid introduction grooves are uniformly arranged in the circumferential direction on the inner diameter side. In this embodiment, the fluid introduction grooves 16 have the function of introducing a fluid, but they may also be used to introduce a fluid.

[0026] The portions of the sliding surface 11 other than the hydrodynamic grooves 13 and the fluid introduction grooves 16 are flat lands 12 (see FIG. 2). As shown in detail in FIG. 3, the lands 12 have land portions 12a between the hydrodynamic grooves 13 adjacent in the circumferential direction, land portions 12b between the fluid introduction grooves 16 adjacent in the circumferential direction, and lands 12c and 12d, which will be described later. The upper surfaces (i.e., axial end surfaces) of these lands are arranged in the same plane and form the flat surface of the land 12.

[0027] 2, the dynamic pressure generating groove 13 has a starting end that communicates with the outer space S2 and extends in an arc shape inclined from the starting end toward the inner diameter side in the forward rotation direction of the rotating seal ring 20. The dynamic pressure generating groove 13 is a positive direction dynamic pressure generating groove that generates positive pressure at its terminal end when the rotating seal ring 20 rotates forward.

[0028] The dynamic pressure generating groove 13 includes a first dynamic pressure generating groove 131 that is relatively long in the radial direction and whose terminal end 131a (see Figure 3) is closer to the fluid introduction groove 16, and a second dynamic pressure generating groove 132 that is relatively short in the radial direction compared to the first dynamic pressure generating groove 131 and whose terminal end 132a (see Figure 3) is further away from the fluid introduction groove 16.

[0029] A predetermined number of first dynamic pressure generating grooves 131 and second dynamic pressure generating grooves 132 respectively constitute a first dynamic pressure generating groove group and a second dynamic pressure generating groove group. In this embodiment, the first dynamic pressure generating groove group is made up of six first dynamic pressure generating grooves 131 in the circumferential direction, and the second dynamic pressure generating groove group is made up of three second dynamic pressure generating grooves 132 in the circumferential direction, and these first dynamic pressure generating groove groups and second dynamic pressure generating groove groups are provided alternately.

[0030] Note that adjacent first dynamic pressure generating grooves 131 and second dynamic pressure generating grooves 132 are spaced apart at the same distance in the circumferential direction as the distance between the first dynamic pressure generating grooves 131 and the distance between the second dynamic pressure generating grooves 132. In other words, the first dynamic pressure generating grooves 131 and the second dynamic pressure generating grooves 132 are all arranged at equal intervals in the circumferential direction, i.e., at equal pitches, but this is not limiting, and adjacent first dynamic pressure generating grooves 131 and second dynamic pressure generating grooves 132 may be spaced apart at a distance different from the distance between the first dynamic pressure generating grooves 131 in the circumferential direction and the distance between the second dynamic pressure generating grooves 132 in the circumferential direction.

[0031] The dynamic pressure generating grooves 13 are not limited to extending in an arc shape inclined in the forward rotation direction of the rotary seal ring 20, but may extend linearly inclined in the forward rotation direction of the rotary seal ring 20, for example.

[0032] As shown in Figure 3, the fluid introduction groove 16 is composed of a fluid guide groove portion 17 that communicates with the internal space S1, and a Rayleigh step 18 and a reverse Rayleigh step 18' that serve as dynamic pressure generating portions that extend circumferentially concentrically with the stationary seal ring 10 from the outer diameter side of the fluid guide groove portion 17 toward the forward or reverse rotation direction of the rotating seal ring 20.

[0033] The fluid guide groove portion 17 is formed to be deeper than the depth of the dynamic pressure generating groove 13. The Rayleigh step 18 and the inverse Rayleigh step 18' are formed to be shallower than the depth of the fluid guide groove portion 17 and to be approximately the same depth as the depth of the dynamic pressure generating groove 13. The fluid guide groove portion 17 may have the same depth as the dynamic pressure generating groove 13. The Rayleigh step 18 and the inverse Rayleigh step 18' are formed to have a circumferential length longer than the circumferential length of the fluid guide groove portion 17 and the circumferential length of one dynamic pressure generating groove 13.

[0034] The Rayleigh step 18 extends circumferentially concentrically with the stationary seal ring 10 in the forward rotation direction of the rotary seal ring 20, and together with the fluid guide groove portion 17 forms a forward-direction fluid lead-out groove. The reverse Rayleigh step 18' extends circumferentially concentrically with the stationary seal ring 10 in the reverse rotation direction of the rotary seal ring 20, and together with the fluid guide groove portion 17 forms a reverse-direction fluid lead-out groove.

[0035] The fluid introduction groove 16 is arranged radially inward of the first and second dynamic pressure generating groove groups so as to straddle them, in other words, arranged facing each other in the radial direction. More specifically, the rearmost end of the first dynamic pressure generating grooves 131 constituting the first dynamic pressure generating groove group, adjacent to the second dynamic pressure generating groove 132, i.e., the terminal end 131a of the first dynamic pressure generating groove 131Z at the upstream end in the forward rotation direction, faces the fluid introduction groove portion 17 of the fluid introduction groove 16. In other words, the fluid introduction groove portion 17 is located in the extension direction of the terminal end 131a of the rearmost first dynamic pressure generating groove 131Z.

[0036] The terminal end 131a of the foremost first hydrodynamic pressure generating groove 131A of the first hydrodynamic pressure generating grooves 131 constituting the first hydrodynamic pressure generating groove group is located slightly radially outward of the land portion 12b between the circumferentially adjacent fluid introduction grooves 16. All of the first hydrodynamic pressure generating grooves 131 constituting the first hydrodynamic pressure generating groove group are formed toward the land portion 12b between the circumferentially adjacent fluid introduction grooves 16, the Rayleigh step 18, and the fluid guide groove portion 17, and do not face the reverse Rayleigh step 18'. In other words, the reverse Rayleigh step 18' is not located in the extension direction of the terminal end 131a of the rearmost first hydrodynamic pressure generating groove 131Z.

[0037] In contrast, of the second dynamic pressure generating grooves 132 constituting the second dynamic pressure generating groove group, the terminal end 132a of the foremost second dynamic pressure generating groove 132A adjacent to the first dynamic pressure generating groove 131 faces the reverse Rayleigh step 18' of the fluid introduction groove 16. In other words, the reverse Rayleigh step 18' is located in the extension direction of the terminal end 132a of the foremost second dynamic pressure generating groove 132A. Furthermore, the terminal end 132a of the rearmost second dynamic pressure generating groove 132Z of the second dynamic pressure generating grooves 132 constituting the second dynamic pressure generating groove group also faces the reverse Rayleigh step 18' of the fluid introduction groove 16, being spaced further radially than the first dynamic pressure generating groove 131. In other words, all of the second dynamic pressure generating grooves 132 constituting the second dynamic pressure generating groove group face only the reverse Rayleigh step 18'. In other words, for all of the second dynamic pressure generating grooves 132, only the reverse Rayleigh step 18' is located in the extension direction.

[0038] In this way, the land portion 12d between the second dynamic pressure generating groove 132 facing the reverse Rayleigh step 18' is radially longer than the land portion 12c between the Rayleigh step 18, the fluid guide groove portion 17, and the first dynamic pressure generating groove 131 facing them.

[0039] As shown in Figure 3, the dynamic pressure generating grooves 13 are arranged in such a manner that the ends 131a of the four first dynamic pressure generating grooves 131 are closely spaced relative to the Rayleigh step 18 and the fluid guide groove portion 17 via the land portion 12c, while the ends 132a of the three second dynamic pressure generating grooves 132 are spaced apart relative to the inverse Rayleigh step 18' via the land portion 12d.

[0040] The term "sparse state" used here refers to a state in which the proportion of the area on the sliding surface 11 where the dynamic pressure generating grooves 13 are arranged, particularly around the terminal ends 18a' of the inverted Rayleigh steps 18', is smaller than the proportion of the area where the dynamic pressure generating grooves 13 are arranged, particularly around the terminal ends 18a of the Rayleigh steps 18. It can also be said that the total volume of the dynamic pressure generating grooves 13 arranged particularly around the terminal ends 18a' of the inverted Rayleigh steps 18', i.e., the second dynamic pressure generating grooves 132, is smaller than the total volume of the dynamic pressure generating grooves 13 arranged particularly around the terminal ends 18a of the Rayleigh steps 18, i.e., the first dynamic pressure generating grooves 131. In this embodiment, the second dynamic pressure generating grooves 132 are all spaced a long distance apart, particularly in the radial direction, from the inverted Rayleigh steps 18', while the first dynamic pressure generating grooves 131 are all spaced a short distance apart, i.e., close to, the Rayleigh steps 18. As will be explained in more detail later using another embodiment, even in a case such as that shown in Figure 6, where there are no second dynamic pressure generating grooves 132 arranged around the inverse Rayleigh step 18', particularly around the terminal end 18a', it can be said that the dynamic pressure generating grooves 13 arranged around the inverse Rayleigh step 18', particularly around the terminal end 18a', are sparser than the dynamic pressure generating grooves 13 arranged around the Rayleigh step 18, particularly around the terminal end 18a.

[0041] Next, the operation of the stationary seal ring 10 and the rotating seal ring 20 during relative rotation will be described with reference to Figures 4 and 5. In this embodiment, the operation of the rotating seal ring 20 when stopped, rotating forward, and rotating backward will be described in that order.

[0042] First, when the rotary seal ring 20 is not rotating, the sealed fluid F flows into the fluid inlet groove 16. Furthermore, since the static seal ring 10 is biased toward the rotary seal ring 20 by the elastic member 7, the sliding surfaces 11, 21 are in contact with each other, and almost no sealed fluid F leaks out between the sliding surfaces 11, 21 into the external space S2.

[0043] As shown in FIG. 4, at low speeds immediately after the rotating seal ring 20 starts to rotate relative to the stationary seal ring 10 in the forward rotation direction, the sealed fluid F in the Rayleigh step 18 moves in the forward rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21, and the sealed fluid F in the inner space S1 is drawn into the fluid guide groove portion 17.

[0044] That is, in the fluid introduction groove 16, the sealed fluid F moves from the fluid guide groove portion 17 toward the downstream end 18a of the Rayleigh step 18 in the direction of relative rotation, as shown by arrow H1, and a force acts on the fluid guide groove portion 17 to draw the sealed fluid F as shown by arrow H1. Note that the flows of the sealed fluid F and the atmosphere A in Figure 4 are shown schematically without specifying the relative rotational speed of the rotating seal ring 20.

[0045] The pressure of the sealed fluid F that has moved toward the end 18a of the Rayleigh step 18 is increased at and near the end 18a of the Rayleigh step 18. That is, a positive pressure is generated at and near the end 18a of the Rayleigh step 18.

[0046] Since the depth of the Rayleigh step 18 is shallow, a positive pressure is generated at and near the end 18a of the Rayleigh step 18 even if the rotation speed of the rotary seal ring 20 is low and the amount of movement of the sealed fluid F is small.

[0047] Furthermore, the sliding surfaces 11, 21 are slightly separated from each other by the force of the positive pressure generated at and near the end 18a of the Rayleigh step 18. As a result, the sealed fluid F flows between the sliding surfaces 11, 21 from the end 18a of the Rayleigh step 18 and the inner space S1 side. The presence of the sealed fluid F between the sliding surfaces 11, 21 improves lubrication even during low-speed rotation, and makes it possible to suppress wear between the sliding surfaces 11, 21.

[0048] Furthermore, at low speeds immediately after the rotating seal ring 20 begins to rotate relative to the stationary seal ring 10 in the forward rotation direction, the sealed fluid F in the inverted Rayleigh step 18' moves in the forward rotation direction of the rotary seal ring 20 due to shear forces with the sliding surface 21, generating a relative negative pressure at and near the terminal end 18a' of the inverted Rayleigh step 18'. As a result, a portion of the sealed fluid F that flows out from the terminal end 18a of the Rayleigh step 18 to between the sliding surfaces 11 and 21, as indicated by arrow H2, is sucked in and recovered from the terminal end 18a' of the adjacent downstream inverted Rayleigh step 18' via the land portion 12b, as indicated by arrow H3. Furthermore, the sealed fluid F enters the fluid guide groove 17 from the inverted Rayleigh step 18', and a force acts in the fluid guide groove 17 to push a portion of the sealed fluid F into the internal space S1.

[0049] On the other hand, in the dynamic pressure generating grooves 13, when the relative rotation speed between the rotating seal ring 20 and the stationary seal ring 10 is low, the atmosphere A does not become sufficiently dense within the dynamic pressure generating grooves 13, so high positive pressure is not generated, and the force due to the positive pressure generated by the dynamic pressure generating grooves 13 is relatively smaller than the force due to the positive pressure generated at and near the end 18a of the Rayleigh step 18. Therefore, when the rotating seal ring 20 is rotating at a low speed, the force due to the positive pressure generated at and near the end 18a of the Rayleigh step 18 mainly separates the sliding surfaces 11, 21.

[0050] 4, when the relative rotational speed of the rotating seal ring 20 increases, the atmosphere A in the dynamic pressure generating grooves 13 moves in the forward rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21, and the atmosphere A in the outer space S2 is drawn into the dynamic pressure generating grooves 13. That is, in the first dynamic pressure generating groove 131 and the second dynamic pressure generating groove 132, a large amount of atmosphere A moves from the starting ends 131b, 132b toward the terminal ends 131a, 132a as indicated by arrow L1, and positive pressure is generated at and near the terminal ends 131a, 132a.

[0051] In this way, the force due to the positive pressure generated at and near the end 18a of the Rayleigh step 18 is added to the force due to the positive pressure generated at and near the end 131a, 132a of the dynamic pressure generating groove 13, causing the sliding surfaces 11, 21 to move further apart compared to when the vehicle is moving at low speed. As a result, mainly the air A in the dynamic pressure generating groove 13, as indicated by the arrow L2, flows between the sliding surfaces 11, 21.

[0052] At this time, the air A mixed with the sealed fluid F indicated by the arrow L3 in the dynamic pressure generating groove 13 is pushed out from the terminal ends 131a, 132a and their vicinity toward the inner diameter side, i.e., toward the sealed fluid F side, by the air A indicated by the arrow L1, which has a large energy such as a flow velocity.

[0053] The sliding component of this embodiment is designed so that the positive pressure generating capacity of the dynamic pressure generating grooves 13 as a whole is much greater than the positive pressure generating capacity of the fluid introduction grooves 16 as a whole during high speed rotation in the forward direction, and therefore ultimately, only the atmosphere A exists between the sliding surfaces 11 and 21, i.e., gas lubrication is achieved.

[0054] In this way, when the rotating seal ring 20 starts to rotate relative to the stationary seal ring 10 in the forward direction, the sliding surfaces 11, 21 are lubricated by the sealed fluid F flowing out from the fluid introduction groove 16 between the sliding surfaces 11, 21, and during high-speed rotation, the sliding surfaces 11, 21 are separated from each other by the positive pressure generated by the atmosphere A in the dynamic pressure generating grooves 13, and the sealed fluid F and the atmosphere A are introduced between the sliding surfaces 11, 21, improving lubrication and suppressing wear between the sliding surfaces 11, 21 from the start of relative rotation through to high-speed rotation. In addition, since the dynamic pressure generating grooves 13 extend to the inner space S1, which is the sealed fluid space, and the gas-liquid interface is located on the sealed fluid space side, the sealed fluid F is less likely to leak.

[0055] Next, the reverse rotation of the rotary seal ring 20 will be described with reference to Figure 5. As shown in Figure 5, when the rotary seal ring 20 rotates in the reverse direction relative to the stationary seal ring 10, the sealed fluid F in the Rayleigh step 18 moves in the reverse rotation direction of the rotary seal ring 20 due to shear with the sliding surface 21. As a result, the sealed fluid F enters the fluid guide groove 17 on the downstream side in the relative rotation direction, and a force is exerted in the fluid guide groove 17 to push out a portion of the sealed fluid F, as shown by arrow H1'. Note that the flows of the sealed fluid F and atmosphere A in Figure 5 are shown schematically without specifying the relative rotational speed of the rotary seal ring 20.

[0056] Meanwhile, the sealed fluid F in the reverse Rayleigh step 18' moves in the reverse rotation direction of the rotary seal ring 20 due to shear with the sliding surface 21, and positive pressure is generated at the end 18a' and its vicinity. At this time, since the second dynamic pressure generating groove 132 is separated by a long distance in the radial direction from the reverse Rayleigh step 18', i.e., the radial length of the land 12d is long, a relatively high positive pressure is generated at the end 18a' and its vicinity. As a result, the sealed fluid F flows into the space between the sliding surfaces 11 and 21 from the end 18a' (see arrow H3') of the reverse Rayleigh step 18' and the inner space S1 side.

[0057] In this way, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 10, the sealed fluid F sucked into the fluid inlet groove 16 is supplied from the end 18a' of the reverse Rayleigh step 18' between the sliding surfaces 11, 21, thereby preventing poor lubrication. In addition, the provision of the fluid guide groove portion 17 makes it possible to retain a large amount of the sealed fluid F.

[0058] In addition, since a land 12b extends circumferentially between the reverse Rayleigh step 18' and the adjacent downstream Rayleigh step 18, the sealed fluid flowing out circumferentially from the reverse Rayleigh step 18' easily flows to the downstream Rayleigh step 18.

[0059] As explained above, when the rotary seal ring 20 is rotating in the reverse direction, the sealed fluid F supplied from the terminal end 18a' of the reverse Rayleigh step 18' between the sliding faces 11, 21 is mostly supplied to the land 12b and land 12d between the adjacent fluid introduction grooves 16, and the radial distance to the second dynamic pressure generating groove 132 in the land 12d is greater than that in the land 12c. In other words, the first dynamic pressure generating groove 131 is densely packed relative to the Rayleigh step 18, while the second dynamic pressure generating groove 132 is sparsely arranged relative to the reverse Rayleigh step 18'. Therefore, the sealed fluid F is prevented from immediately flowing into the second dynamic pressure generating groove 132, and a relatively high positive pressure is likely to be generated at the terminal end 18a' of the reverse Rayleigh step 18' and its vicinity, that is, between the land 12b and land 12d. This allows a gap sufficient to allow the sealed fluid F to flow between the sliding faces 11, 21, thereby allowing the sliding faces 11, 21 to be sufficiently lubricated.

[0060] Furthermore, while the terminal end 131a of the first dynamic pressure generating groove 131 is densely packed relative to the terminal end 18a of the Rayleigh step 18, the terminal end 132a of the second dynamic pressure generating groove 132 is sparsely arranged relative to the terminal end 18a' of the reverse Rayleigh step 18'.Therefore, when positive pressure is generated in the reverse Rayleigh step 18' during reverse rotation, there is less influence from the negative pressure generated on the terminal end 132a side of the second dynamic pressure generating groove 132, and pressure is more likely to build up at the terminal end 18a' of the reverse Rayleigh step 18' and its vicinity, that is, at the land portions 12b and 12d.

[0061] Furthermore, since there are multiple areas where the reverse Rayleigh steps 18' and the second dynamic pressure generating grooves 132 are sparse, i.e., land portions 12b and 12d, arranged circumferentially around the sliding surface 11, pressure is likely to build up at the ends 18a' of the reverse Rayleigh steps 18' at multiple locations around the sliding surface 11 during reverse rotation, allowing the sliding surfaces 11 and 21 to be sufficiently lubricated.

[0062] Furthermore, since the Rayleigh step 18 is arranged on the reverse rotation direction side of the reverse Rayleigh step 18', a portion of the sealed fluid F that flows between the sliding surfaces 11, 21 from the terminal end 18a' of the reverse Rayleigh step 18', as shown by arrow H3', is sucked in and recovered from the terminal end 18a of the adjacent downstream Rayleigh step 18 via the land portion 12b, as shown by arrow H2', and is less likely to leak into the external space S2, which is the leakage space.

[0063] Furthermore, since the Rayleigh step 18 and the reverse Rayleigh step 18' have an approximately T-shaped configuration and share the fluid guide groove portion 17, in both forward and reverse rotation, in addition to the sealed fluid F in the fluid guide groove portion 17, when positive pressure is generated on one side, the sealed fluid F in the Rayleigh step on the other side can be utilized, and a sufficient amount of sealed fluid F can be used to efficiently generate positive pressure.

[0064] Furthermore, since the first dynamic pressure generating groove 131 and the second dynamic pressure generating groove 132 are spiral grooves that extend in an arc shape, inclined from the starting points 131b and 132b toward the inner diameter side, positive pressure can be efficiently generated at the end points 131a and 132a by using the fluid, in this case gas, on the outer space S2 side, which is the leakage space.

[0065] The forward direction fluid lead-out groove is made up of a fluid guide groove portion 17 that communicates with the internal space S1, and a Rayleigh step 18 that serves as a dynamic pressure generating portion that extends circumferentially concentrically with the stationary seal ring 10 from the outer diameter side of the fluid guide groove portion 17 toward the forward rotation direction of the rotating seal ring 20, while the reverse direction fluid lead-out groove is made up of a fluid guide groove portion 17 that communicates with the internal space S1, and a reverse Rayleigh step 18' that serves as a dynamic pressure generating portion that extends circumferentially concentrically with the stationary seal ring 10 from the outer diameter side of the fluid guide groove portion 17 toward the reverse rotation direction of the rotating seal ring 20. Furthermore, since the Rayleigh step 18 and the reverse Rayleigh step 18' extend in the relative forward or reverse rotation direction, during forward or reverse rotation, the sealed fluid F flows out mostly in the circumferential direction, i.e., toward the land portion 12b, from the terminal end 18a of the Rayleigh step 18 or the terminal end 18a' of the reverse Rayleigh step 18', and is therefore less likely to be drawn in from the terminal end 132a of the second dynamic pressure generating groove 132. [Example]

[0066] Next, a sliding element according to a second embodiment will be described with reference to Fig. 6. Note that a description of the same configuration as in the first embodiment will be omitted.

[0067] In the first embodiment, the radial length of the second dynamic pressure generating groove 132 is shorter than that of the first dynamic pressure generating groove 131, so that the dynamic pressure generating groove 13 is densely packed relative to the Rayleigh step 18 but sparsely packed relative to the inverse Rayleigh step 18'. However, in the sliding component of the second embodiment, the dynamic pressure generating groove that faces the inverse Rayleigh step 18' in the extension direction is omitted. In other words, none of the dynamic pressure generating grooves 13 of the second embodiment extend toward the land portion 12d in the extension direction, so that the dynamic pressure generating grooves 13 are sparsely packed relative to the inverse Rayleigh step 18'.

[0068] This slightly reduces the positive pressure generating ability of the dynamic pressure generating groove 13 as a whole during forward rotation, but it further prevents the sealed fluid F from leaking out from the dynamic pressure generating groove that faces the reverse Rayleigh step 18' in the extension direction. [Example]

[0069] Next, a sliding element according to a third embodiment will be described with reference to Fig. 7. Note that a description of the same configuration as in the first embodiment will be omitted.

[0070] In the first embodiment, the radial length of the second dynamic pressure generating groove 132 is shorter than that of the first dynamic pressure generating groove 131, so that the dynamic pressure generating groove 13 is densely packed relative to the Rayleigh step 18 but sparsely packed relative to the inverse Rayleigh step 18'. However, in the sliding component of the third embodiment, the first dynamic pressure generating groove 131 and the second dynamic pressure generating groove 232 have the same radial length, and the number of second dynamic pressure generating grooves 232 facing the inverse Rayleigh step 18' in the extension direction is fewer than the number of first dynamic pressure generating grooves 131 facing the Rayleigh step 18 in the extension direction, so that the dynamic pressure generating grooves 13 are sparsely packed relative to the inverse Rayleigh step 18'.

[0071] According to this, during reverse rotation, some of the sealed fluid F is likely to be sucked in from the second dynamic pressure generating groove 232 that faces the reverse Rayleigh step 18' in the extension direction, but since the second dynamic pressure generating groove 232 extends to the side of the inner space S1, which is the sealed fluid space, during forward rotation the gas-liquid interface is located on the sealed fluid space side, making it difficult for the sealed fluid F to leak. [Example]

[0072] Next, a sliding element according to a fourth embodiment will be described with reference to Fig. 8. Note that a description of the same configuration as in the first embodiment will be omitted.

[0073] In the above-mentioned Example 1, the Rayleigh step 18 and the reverse Rayleigh step 18' are integrally formed as a fluid introduction groove 16 having an approximately T-shape that shares the fluid guide groove portion 17, but in the sliding part of this Example 4, the Rayleigh step 18 and the fluid guide groove portion 17 form a forward direction fluid lead-out groove 26, and the reverse Rayleigh step 18' and the fluid guide groove portion 17' form a reverse direction fluid lead-out groove 26', and these are arranged with the fluid guide groove portions 17, 17' spaced apart from each other in the circumferential direction.

[0074] This allows the forward fluid inlet / outlet groove 26 and the reverse fluid inlet / outlet groove 26' to be separated, so that in either forward or reverse rotation, the movement of the sealed fluid F in one groove is less likely to affect the other, making it easier to design the grooves to obtain the required positive pressure. [Example]

[0075] Next, a sliding element according to a fifth embodiment will be described with reference to Fig. 9. Note that a description of the same configuration as in the first embodiment will be omitted.

[0076] The dynamic pressure generating grooves 23 are open to and communicate with the leakage space, and are recessed linearly, inclining downstream as they approach the sealed fluid space, to their terminal ends 23a. The radial positions of the terminal ends 23a of the multiple juxtaposed dynamic pressure generating grooves 23 gradually change along the circumferential direction, and the terminal ends 23a are arranged on a smooth, continuous imaginary curve that is sinusoidal in shape along the circumferential direction. Note that, although not limited to this embodiment and not particularly shown, the imaginary curve on which the terminal ends 23a are arranged does not have to have periodicity like a sinusoidal wave.

[0077] The dynamic pressure generating grooves 23 are arranged in groups of dynamic pressure generating grooves 23A to 23L, which are equally spaced in the circumferential direction, with one fluid introduction groove 16 arranged per dynamic pressure generating groove group.

[0078] 9, the inverse Rayleigh step 18' is located in the extension direction of the dynamic pressure generating groove 23L whose terminal end 23a is located closest to the leakage space (here, on the outer diameter side), and the land portion 12d is located in the extension direction of the dynamic pressure generating groove 23A whose terminal end 23a is located closer to the sealed fluid space (here, on the inner diameter side) than the dynamic pressure generating groove 23L. The Rayleigh step 18 is located in the extension direction via the land portion 12c of the dynamic pressure generating grooves 23F to 23H whose terminal end 23a is located closer to the sealed fluid space (here, on the inner diameter side). In this way, the dynamic pressure generating grooves 23 are arranged densely with the terminal end 23a in close proximity to the Rayleigh step 18 and fluid guide groove portion 17 via the land portion 12c. In contrast, on the side of the inverse Rayleigh step 18', the terminal end 23a is spaced apart via the land portion 12d and arranged sparsely.

[0079] According to this, since the multiple terminal ends 23a are arranged on a sinusoidal virtual curve, on the sliding surface 211, during forward rotation of the rotary seal ring 20, positive pressure is generated at different radial positions along the circumferential direction, and the radial pressure gradient on the sliding surface 211 becomes small, making it easy for a uniform fluid film to be formed over a wide area of ​​the sliding surface 211. This improves the lubrication between the sliding surfaces 211, 21. In addition, during reverse rotation, since the terminal ends 23a of the dynamic pressure generating grooves 23 are spaced apart from the reverse Rayleigh step 18' and are in a sparse state, pressure is easily generated in the land portion 12d.

[0080] In this embodiment 5, the inverse Rayleigh step 18' is located in the extension direction of the dynamic pressure generating groove 23L whose end 23a is located closest to the sealed fluid space (here, the outer diameter side), and the Rayleigh step 18 is located in the extension direction of the dynamic pressure generating grooves 23F to 23H whose end 23a is located relatively closer to the leakage space (here, the inner diameter side). However, this is not limited to this, and the Rayleigh step 18 or the inverse Rayleigh step 18' may be located in the extension direction of any of the dynamic pressure generating grooves 23 in the dynamic pressure generating grooves 23A to 23L as long as the Rayleigh step 18 or the inverse Rayleigh step 18' is arranged densely relative to the Rayleigh step 18 and sparsely relative to the inverse Rayleigh step 18'. [Example]

[0081] Next, a sliding element according to a sixth embodiment will be described with reference to Fig. 10. Note that the description of the same configuration as in the first embodiment will be omitted.

[0082] In the sliding component of Example 6, the first dynamic pressure generating groove 131 and the second dynamic pressure generating groove 133 have the same radial length, and the groove width of the second dynamic pressure generating groove 133 facing the inverse Rayleigh step 18' in the extension direction is shorter than the first dynamic pressure generating groove 131 facing the Rayleigh step 18 in the extension direction. In this way, the dynamic pressure generating groove 13 is sparsely spaced relative to the inverse Rayleigh step 18'.

[0083] According to this, during reverse rotation, some of the sealed fluid F is sucked in from the second dynamic pressure generating groove 133 that faces the reverse Rayleigh step 18' in the extension direction, but the amount of sucked in is small. Also, since the second dynamic pressure generating groove 133 extends to the side of the inner space S1, which is the sealed fluid space, during forward rotation the gas-liquid interface is located on the sealed fluid space side, making it difficult for the sealed fluid F to leak. [Example]

[0084] Next, a sliding element according to a seventh embodiment will be described with reference to Fig. 11. Note that a description of the same configuration as in the first embodiment will be omitted.

[0085] In the sliding component of Example 7, the first dynamic pressure generating groove 131 and the second dynamic pressure generating groove 134 have the same radial length, and the depth dimension of the second dynamic pressure generating groove 134, which faces the inverse Rayleigh step 18' in the extension direction, is shorter than the first dynamic pressure generating groove 131, which faces the Rayleigh step 18 in the extension direction. In this way, the dynamic pressure generating grooves 13 are sparsely spaced relative to the inverse Rayleigh step 18'.

[0086] According to this, during reverse rotation, some of the sealed fluid F is sucked in from the second dynamic pressure generating groove 134 that faces the reverse Rayleigh step 18' in the extension direction, but the absolute value of the negative pressure generated in the second dynamic pressure generating groove 134 at a predetermined rotation speed is smaller than that of the first dynamic pressure generating groove 131, so the effect on the positive pressure generated at and near the end 18' of the reverse Rayleigh step 18' is small. Furthermore, because the second dynamic pressure generating groove 134 extends to the side of the inner space S1, which is the sealed fluid space, during forward rotation the gas-liquid interface is located on the sealed fluid space side, making it difficult for the sealed fluid F to leak.

[0087] 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.

[0088] For example, in the first to seventh embodiments, mechanical seals for automobiles have been described as examples of sliding parts, but other mechanical seals for general industrial machinery, etc. Also, the sliding parts are not limited to mechanical seals, and may be sliding bearings or other sliding parts other than mechanical seals.

[0089] Furthermore, in the above-described first to seventh embodiments, examples have been described in which the dynamic pressure generating grooves and the fluid introduction grooves are provided in the stationary seal ring, but the dynamic pressure generating grooves and the fluid introduction grooves may also be provided in the rotary seal ring.

[0090] In addition, in the above-described Examples 1 to 7, the sealed fluid side has been described as the high-pressure side and the leakage side as the low-pressure side, but the sealed fluid side may be the low-pressure side and the leakage side may be the high-pressure side, or the sealed fluid side and the leakage side may be at approximately the same pressure.

[0091] Furthermore, although the mechanical seals having sliding elements in Examples 1 to 7 have been described as being of the outside type, they may also be applied to an inside type that seals against fluid leaking from the outer periphery of the sliding surface in the inward direction. When the inside type is employed, as in the sliding element 30 shown in Fig. 12, for example, the first dynamic pressure generating groove 331 and the second dynamic pressure generating groove 332, which are the dynamic pressure generating grooves 33, may be provided on the inner diameter side, i.e., on the side of the inner space S11, which is the leakage space, and the fluid introduction groove 36, which has the Rayleigh step 38, the inverse Rayleigh step 38', and the fluid guide groove 37, may be provided on the outer diameter side, i.e., on the side of the outer space S12, which is the sealed fluid space.

[0092] Furthermore, in the above-described Examples 1 to 7, the dynamic pressure generating grooves are explained as being in communication with the leakage space, but this is not limiting, and they do not have to be in communication as long as they can generate dynamic pressure.

[0093] In addition, in the above-described Examples 1 to 7, the fluid introduction groove is explained as being in communication with the sealed fluid space, but this is not limited thereto, and it does not have to be in communication as long as it can store the sealed fluid, and for example, a dimple or the like may be used.

[0094] Furthermore, in Examples 1 to 7, the fluid introduction groove has a Rayleigh step, but this is not limited to this and it is sufficient if positive pressure can be generated during forward and reverse rotation. For example, the Rayleigh step portion may be an inclined groove that is inclined circumferentially and extends radially.

[0095] Furthermore, in the above-described Examples 1 to 7, a plurality of fluid introduction grooves are provided in the circumferential direction, but it is sufficient that at least one fluid introduction groove is provided.

[0096] In addition, in the first to seventh embodiments, the sealed fluid 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 a mist-like mixture of liquid and gas.

[0097] Furthermore, in the above-described Examples 1 to 7, 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. [Explanation of symbols]

[0098] 10 Stationary sealing ring 11,21 sliding surface 12a~12d Land section 13 Dynamic pressure generating groove (positive direction dynamic pressure generating groove) 16 Fluid inlet groove 17 Fluid guide groove (forward fluid lead-in / out groove / reverse fluid lead-in / out groove) 18 Rayleigh step (forward flow inlet / outlet groove) 18' Reverse Rayleigh step (reverse fluid intake / exit groove) 18a,18a' Termination 20 Rotating seal ring 23 Dynamic pressure generating groove 23A~23L Dynamic pressure generating groove 23a Termination 26 Reverse fluid lead-in / out groove 26 Forward direction fluid lead-in / out groove 131 First dynamic pressure generating groove 131a Termination 131 Second dynamic pressure generating groove 132a Termination 133 Second dynamic pressure generating groove 134 Second dynamic pressure generating groove 232 Second dynamic pressure generating groove F Sealed fluid S1 Inner space (sealed fluid space) S2 External space (leakage space) S11 Internal space (leakage space) S12 Outside space (sealed fluid space)

Claims

1. A sliding component in which sliding surfaces of a pair of sliding rings rotate relative to each other to separate a sealed fluid space from a leakage space, at least one of the sliding surfaces is provided with a forward dynamic pressure generating groove communicating with the leakage space, a forward fluid lead-in / out groove isolated from the forward dynamic pressure generating groove by a land portion and communicating with the sealed fluid space, and a reverse fluid lead-in / out groove isolated from the forward dynamic pressure generating groove by a land portion and communicating with the sealed fluid space, A sliding component in which the forward-direction dynamic pressure generating grooves are arranged more sparsely relative to the reverse-direction fluid inlet / outlet grooves per unit length than to the forward-direction fluid inlet / outlet grooves per unit length.

2. 2. A sliding component according to claim 1, wherein the terminal ends of the forward-direction dynamic pressure generating grooves are more spaced apart from the terminal ends of the backward-direction fluid inlet / outlet grooves than from the terminal ends of the forward-direction fluid inlet / outlet grooves.

3. 2. The sliding component according to claim 1, wherein the sparse state is formed by arranging the forward-direction hydrodynamic pressure generating grooves, which have a smaller total volume than the forward-direction fluid inlet / outlet grooves, relative to the reverse-direction fluid inlet / outlet grooves.

4. 2. The sliding component according to claim 1, wherein the sparse state is formed by arranging the forward direction hydrodynamic pressure generating grooves, which are radially shorter than the forward direction fluid inlet / outlet grooves, relative to the reverse direction fluid inlet / outlet grooves.

5. The sliding element according to claim 1 , wherein a plurality of the regions in the sparse state are arranged in the circumferential direction of the sliding surface.

6. 6. The sliding component according to claim 1, wherein the forward-direction hydrodynamic pressure generating groove is a spiral groove extending in an arc shape inclined from a starting end relative to the radial direction, the forward-direction fluid lead-out groove has a fluid guide groove portion communicating with the sealed fluid space and a Rayleigh step extending in the relative forward rotation direction, and the reverse-direction fluid lead-out groove has a fluid guide groove portion communicating with the sealed fluid space and a reverse Rayleigh step extending in the relative reverse rotation direction.

7. 7. The sliding component according to claim 6, wherein the forward direction fluid inlet / outlet groove and the reverse direction fluid inlet / outlet groove have a generally T-shape and share the fluid guide groove portion.

8. 6. A sliding element according to claim 1, wherein the forward direction fluid inlet / outlet groove is disposed on the side of the reverse direction fluid inlet / outlet groove in the relative reverse rotation direction.

Images