Sliding parts

Abstract

Provided is a sliding component that can suppress wear between sliding surfaces during both forward rotation and reverse rotation, and can suppress leakage of a sealed fluid.　An annular sliding component 10 is disposed at a location of relative rotation of a rotating machine, slides relative to another sliding component 20, and comprises: a plurality of fluid introduction grooves 16 in a sliding surface 11, the grooves communicating with a space S2 on a sealed fluid F side and introducing the sealed fluid F thereinto; and a plurality of inclined grooves 14 extending from a leakage side to the sealed fluid F side and generating dynamic pressure, wherein a recess 15 is provided in the sliding surface 11 of the sliding component 10, and is disposed at least between the fluid introduction grooves 16 adjacent in the circumferential direction.

Description

[Technical field]

[0001] The present invention relates to a sliding part that rotates relative to another sliding part, for example, a sliding part used in a shaft sealing device that seals a 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] As an example of a shaft sealing device for preventing leakage of a sealed fluid, a mechanical seal is provided with a pair of annular sliding components that rotate relative to one another and slide against each other on their sliding surfaces. In such mechanical seals, there has been a demand in recent years for the purpose of environmental measures and the like to reduce the energy lost due to sliding.

[0003] For example, the mechanical seal shown in Patent Document 1 is configured such that a pair of annular sliding parts are rotatable relative to each other, a sealed fluid is present in the outer space, and a low-pressure fluid is present in the inner space. One of the sliding parts is provided with a fluid introduction groove that communicates with the outer space where the sealed fluid is present and has a closed inner diameter end, and is provided with an inclined groove that communicates with the inner space where the low-pressure fluid is present, extends in an arc shape while inclining in the circumferential direction from the inner diameter end toward the outer diameter side, and has a closed outer diameter end downstream in the relative rotation direction. According to this, when the pair of sliding parts start to rotate relative to each other, the sealed fluid present in the outer space is introduced into the fluid introduction groove, thereby lubricating the sliding surfaces of the pair of sliding parts, and when the pair of sliding parts rotate at high speed, the low-pressure fluid present in the inner space is introduced into the inclined groove, generating a positive pressure at and near the outer diameter end, slightly separating the sliding surfaces of the pair of sliding parts, thereby realizing low friction. In addition, during high-speed rotation, the sealed fluid that flows from the outer space between the sliding surfaces and moves toward the inner diameter side of the sliding surfaces is sucked in by the inclined grooves, thereby preventing the sealed fluid from leaking from between the pair of sliding parts into the low-pressure inner space. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6444492 (pages 9 and 10, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the sliding parts such as those described in Patent Document 1, the inclined groove is arranged on the leakage side of one of the sliding parts and extends from the inner diameter end to the outer diameter side so that the leakage side fluid is introduced during forward rotation, which makes it possible to reduce wear and suppress leakage. However, during reverse rotation, although the sealed fluid flows out from the fluid introduction groove between the sliding surfaces, resulting in excellent lubrication, there is a problem in that this sealed fluid leaks out from between the pair of sliding parts into the internal space.

[0006] The present invention has been made in consideration of such problems, and has an object to provide a sliding component that can suppress wear between the sliding surfaces during both forward and reverse rotation (hereinafter sometimes referred to as both rotations), and can suppress leakage of the sealed fluid. [Means for solving the problem]

[0007] In order to solve the above problems, the sliding component of the present invention comprises: An annular sliding component is disposed at a relative rotating portion of a rotary machine, slides relative to another sliding component, and has a plurality of fluid introduction grooves on a sliding surface which communicate with a space on a sealed fluid side and introduce the sealed fluid, and a plurality of inclined grooves which extend from a leakage side to the sealed fluid side and generate dynamic pressure, The sliding surface of the sliding component is provided with recesses that are disposed at least between the fluid introduction grooves that are adjacent in the circumferential direction. According to this, during reverse rotation, the sealed fluid flowing out from the fluid inlet groove between the sliding surfaces is captured by the recess on the downstream side of the relative rotation of the fluid inlet groove, thereby reducing leakage of the sealed fluid into the space on the leakage side. Therefore, during both rotations, the sliding surfaces can be separated to suppress wear, and leakage of the sealed fluid from between the pair of sliding parts into the space on the leakage side can be suppressed.

[0008] The recess may be an inverted inclined groove that is provided on the sealed fluid side of the inclined groove, extends in a direction opposite to the inclined groove, and generates dynamic pressure. According to this, during reverse rotation, the sealed fluid flowing out from the fluid inlet groove between the sliding surfaces is captured by the reverse inclined groove downstream of the relative rotation of the fluid inlet groove, and the sealed fluid captured in the reverse inclined groove moves due to shear with the sliding surfaces of other sliding parts and is returned between the sliding surfaces from the end of the reverse inclined groove on the sealed fluid side towards the sealed fluid side, thereby further reducing leakage of the sealed fluid into the leakage side space.

[0009] The recess may be provided only between adjacent ones of the fluid introduction grooves. According to this, there is no recess in a position that radially overlaps with the inclined groove arranged on the leakage side of the fluid introduction groove, and the extension distance of the inclined groove arranged on the leakage side of the fluid introduction groove can be increased. Therefore, during forward rotation, it becomes easier to generate a high positive pressure by the fluid on the leakage side in the inclined groove, and the dynamic pressure effect can be enhanced.

[0010] The fluid introduction groove may have a Rayleigh step. According to this, the Rayleigh step generates dynamic pressure to separate the sliding surfaces slightly and allows the sealed fluid to be introduced between the sliding surfaces, thereby improving the lubrication between the sliding surfaces.

[0011] The fluid introduction groove may have a Rayleigh step extending on both sides in the circumferential direction. According to this, during both rotations, the Rayleigh step generates dynamic pressure to slightly separate the sliding surfaces and allow the sealed fluid to be introduced between the sliding surfaces, thereby improving the lubrication between the sliding surfaces.

[0012] The reverse inclined groove may have a shorter extension distance than the inclined groove. According to this, during reverse rotation, positive pressure can be generated in the reverse inclined groove early.

[0013] The inclined groove and the inversely inclined groove may be continuous grooves. According to this, during reverse rotation, the sealed fluid that attempts to move through the inclined groove toward the leakage side can be returned to the sealed fluid side by the reverse inclined groove, thereby reducing leakage of the sealed fluid into the leakage side space.

[0014] Between the inclined groove and the reverse inclined groove, an annular land portion may be provided which is continuous in the circumferential direction on the sealed fluid side of the inclined groove and has a predetermined radial width or more. According to this, during reverse rotation, the sealed fluid is captured in the reverse inclined groove on the sealed fluid side of the annular land, so that the sealed fluid can be prevented from entering the inclined groove. Also, since the inclined groove and the reverse inclined groove are separated by the annular land, the inclined groove and the reverse inclined groove do not interfere with each other's dynamic pressure generation during both rotations, so that the dynamic pressure effect can be easily exerted.

[0015] In the sliding surface of the sliding component according to the present invention, the inclined groove may have both a radial component and a circumferential component in its extending direction. Similarly, the reverse inclined groove may have both a radial component and a circumferential component in its extending direction, and may extend in the opposite direction from the upstream to the downstream during relative rotation to the inclined groove.

[0016] The sealed fluid may be gas or liquid, or may be a mist of a mixture of liquid and gas. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention. [Diagram 2] 3 is a view showing a sliding surface of a stationary seal ring in the first embodiment as viewed from the axial direction. FIG. [Diagram 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. 4 is an explanatory view of the movement of fluid in the inclined grooves and the reverse inclined grooves during forward rotation, as viewed from the axial direction, on the sliding surface of the stationary seal ring in the first embodiment. [Diagram 5] FIG. 4 is an explanatory view of the movement of fluid in the inclined grooves and the reverse inclined grooves during reverse and forward rotation, as viewed from the axial direction, on the sliding surface of the stationary seal ring in the first embodiment. [Figure 6] 6 is a view showing a sliding surface of a stationary seal ring according to a modified example of the first embodiment, as viewed from the axial direction. FIG. [Figure 7] FIG. 11 is an enlarged view of a sliding surface of a stationary seal ring according to a second embodiment of the present invention, as viewed from the axial direction. [Figure 8] FIG. 11 is an enlarged view of a sliding surface of a stationary seal ring according to a third embodiment of the present invention, as viewed from the axial direction. [Figure 9] FIG. 11 is an explanatory view of the movement of fluid in the inclined grooves and the reverse inclined grooves during forward rotation, as viewed from the axial direction, for the sliding surface of the stationary seal ring in the third embodiment. [Figure 10] FIG. 11 is an explanatory view of the movement of fluid in the inclined grooves and the reverse inclined grooves during reverse and forward rotation, as viewed from the axial direction, on the sliding surface of the stationary seal ring in the third embodiment. [Figure 11] FIG. 11 is an enlarged view of a sliding surface of a stationary seal ring according to a fourth embodiment of the present invention, as viewed from the axial direction. [Figure 12] FIG. 11 is an enlarged view of a sliding surface of a stationary seal ring according to a fifth embodiment of the present invention, as viewed from the axial direction. [Figure 13] FIG. 13 is an enlarged view of a sliding surface of a stationary seal ring according to a sixth embodiment of the present invention, as viewed from the axial direction. [Figure 14] FIG. 13 is an enlarged view of a sliding surface of a stationary seal ring according to a seventh embodiment of the present invention, as viewed from the axial direction. [Figure 15] FIG. 13 is an enlarged view of a sliding surface of a stationary seal ring according to an eighth embodiment of the present invention, as viewed from the axial direction. [Figure 16] FIG. 13 is an enlarged view of a sliding surface of a stationary seal ring according to a ninth embodiment of the present invention, as viewed from the axial direction. [Figure 17] FIG. 23 is an enlarged view of the sliding surface of the stationary seal ring according to the tenth embodiment of the present invention, as viewed from the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the sliding component according to the present invention will be described with reference to the accompanying drawings. EXAMPLES

[0019] A sliding component according to a first embodiment will be described with reference to Figs. 1 to 6. In this embodiment, the sliding component is a mechanical seal. A sealed fluid exists in the outer space of the mechanical seal, and atmosphere exists in the inner space. The outer diameter side of the sliding component constituting the mechanical seal will be described as the sealed fluid side (high pressure side), and the inner diameter side as the leakage side (low pressure side). For ease of explanation, dots may be added to grooves and the like formed on the sliding surface in the drawings.

[0020] 1 is an inside type mechanical seal for automobiles, which seals against a sealed fluid F that is attempting to leak from the outer diameter side to the inner diameter side of a sliding surface, and has an internal space S1 that communicates with the atmosphere A. In this embodiment, an example is shown in which the sealed fluid F is a high-pressure liquid, and the atmosphere A is a gas with a lower pressure than the sealed fluid F.

[0021] The mechanical seal is mainly composed of a rotating seal ring 20 as another sliding part that is mounted on the rotating shaft 1 via a sleeve 2 in a state that it can rotate together with the rotating shaft 1, and a ring-shaped stationary seal ring 10 as a sliding part that is mounted in a non-rotating state and axially movable state on a seal cover 5 fixed to a housing 4 of an attached device, and the static 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. Note that the sliding surface 21 of the rotating seal ring 20 is flat, and this flat surface does not have any recesses such as grooves.

[0022] The stationary seal ring 10 and the rotating seal ring 20 are typically formed by a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but are not limited to this and any sliding material used as a sliding material for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, etc. as 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, SiC-TiN, etc., and examples of carbon include carbonaceous and graphitic mixtures, resin molded carbon, sintered carbon, etc. In addition to the above sliding materials, metal materials, resin materials, surface modification materials (coating materials), composite materials, etc. can also be used.

[0023] As shown in Figures 2 and 3, the rotating seal ring 20 slides relative to the stationary seal ring 10 in a counterclockwise direction as indicated by the solid arrow or in a clockwise direction as indicated by the dotted arrow, and the sliding surface 11 of the stationary seal ring 10 has a plurality of dynamic pressure generating grooves 13 and inclined grooves 13' evenly arranged in the circumferential direction on the inner diameter side, and a plurality of fluid introduction grooves 16 evenly arranged in the circumferential direction on the outer diameter side.

[0024] In the following description of the embodiment, the counterclockwise rotation direction of the rotary seal ring 20 indicated by the solid arrow is the forward rotation direction, and the clockwise rotation direction of the rotary seal ring 20 indicated by the dotted arrow is the reverse rotation direction.

[0025] Further, the portions of the sliding surface 11 other than the dynamic pressure generating grooves 13, the inclined grooves 13', and the fluid introduction grooves 16 are the lands 12 forming a flat surface. In detail, the land 12 has land portions 12a between the dynamic pressure generating grooves 13 adjacent in the circumferential direction, between the inclined grooves 13', and between the dynamic pressure generating grooves 13 and the inclined groove 13', land portions 12b between the fluid introduction grooves 16 adjacent in the circumferential direction, and land portions 12c between the inclined grooves 13' and the fluid introduction grooves 16 spaced apart in the radial direction. These land portions are arranged on the same plane and form the flat surface of the land 12.

[0026] 3, the dynamic pressure generating groove 13 has an outer diameter end 13B extending to a land portion 12b between circumferentially adjacent fluid introduction grooves 16, and is composed of an inclined groove 14 extending from the inner diameter side toward the outer diameter side to generate dynamic pressure, and an inverse inclined groove 15 formed continuously with the outer diameter side of the inclined groove 14, extending in the opposite direction to the inclined groove 14, and serving as a recess to generate dynamic pressure, forming an L shape. Note that the inverse inclined groove 15 serving as a recess is disposed between the fluid introduction grooves 16 adjacent in the circumferential direction.

[0027] In addition, extending in the opposite direction to the inclined groove 14 means that, compared to the inclined groove 14 which extends with an inclination having a component in the forward rotation direction from the inner diameter side to the outer diameter side, the reverse inclined groove 15 extends with an inclination having a component in the reverse rotation direction from the inner diameter side to the outer diameter side.

[0028] In detail, the dynamic pressure generating groove 13 has an inner diameter end 13A, i.e., an inner diameter end of the inclined groove 14, which communicates with the inner space S1 and extends in an arc shape from the inner diameter end 13A toward the outer diameter side while inclining in the forward rotation direction of the rotary seal ring 20, and a reverse inclined groove 15 extending in the opposite direction to the inclined groove 14 is continuously formed at the outer diameter side end of the inclined groove 14. The reverse inclined groove 15 extends linearly while inclining in the reverse rotation direction of the rotary seal ring 20 from the inner diameter side end toward the outer diameter side, and the outer diameter side end, i.e., the outer diameter end 13B of the dynamic pressure generating groove 13 is closed so as not to communicate with the outer space S2. The reverse inclined groove 15 is not limited to extending linearly while inclining, and may extend in an arc shape.

[0029] As shown in Figure 3, the inclined groove 14 is composed of a bottom surface 14a that is flat in the extension direction and parallel to the flat surface of the land 12, and side wall portions 14c, 14d that extend vertically from both side edges of the bottom surface 14a toward the sliding surface 11.

[0030] The reverse inclined groove 15 is composed of a bottom surface 15a that is flat in the extension direction and parallel to the flat surface of the land 12, a wall portion 15b that extends vertically from the edge of the bottom surface 15a on the outer diameter end 13B side toward the sliding surface 11, and side wall portions 15c, 15d that extend vertically from both side edges of the bottom surface 15a toward the sliding surface 11.

[0031] In addition, the dynamic pressure generating groove 13 has an acute angle portion 13C formed by the side wall portion 14d of the inclined groove 14 and the side wall portion 15d of the reverse inclined groove 15, an acute angle portion 13D formed by the wall portion 15b and the side wall portion 15c of the reverse inclined groove 15, and an obtuse angle portion 13E formed by the wall portion 15b and the side wall portion 15d of the reverse inclined groove 15. The acute angle portion 13D is located on the outer diameter side of the acute angle portion 13C and downstream in the reverse rotation direction of the rotating seal ring 20. Furthermore, the acute angle portion 13D has a smaller angle than the acute angle portion 13C. The acute angle portion 13C is formed at approximately the same radial position as the inner diameter side peripheral wall portion 17a of the liquid guide groove portion 17 of the fluid introduction groove 16 described later, and the acute angle portion 13D is formed at approximately the same radial position as the outer diameter side peripheral wall portion 18a of the Rayleigh step 18 of the fluid introduction groove 16 described later.

[0032] The extending distance of the reverse inclined groove 15 is shorter than the extending distance of the inclined groove 14. That is, the lengths of the side walls 15c and 15d of the reverse inclined groove 15 are shorter than the lengths of the side walls 14c and 14d of the continuous inclined groove 14, respectively.

[0033] The depth of the reverse inclined groove 15 is the same as the depth of the inclined groove 14. That is, the bottom surface 15a of the reverse inclined groove 15 is disposed in the same plane as the bottom surface 14a of the continuous inclined groove 14, forming a flat surface. Note that the bottom surface 14a of the inclined groove 14 and the bottom surface 15a of the reverse inclined groove 15 are not limited to being flat surfaces, and may have an inclination or unevenness.

[0034] As shown in FIG. 3, the inclined groove 13' has an outer diameter end 13B' disposed on the inner diameter side of the fluid introduction groove 16, and extends from the inner diameter side toward the outer diameter side to generate dynamic pressure.

[0035] In detail, the inclined groove 13' has an inner diameter end 13A' that is connected to the inner space S1, and extends in an arc shape from the inner diameter end 13A' toward the outer diameter side while inclining in the positive rotation direction of the rotating seal ring 20, and an outer diameter end 13B' that is closed so as to be non-communicating with the fluid introduction groove 16.

[0036] As shown in Figure 3, the inclined groove 13' is composed of a bottom surface 13a' that is flat in the extension direction and parallel to the flat surface of the land 12, a wall portion 13b' that extends vertically from the edge of the outer diameter end 13B' side of the bottom surface 13a' toward the sliding surface 11, and side wall portions 13c', 13d' that extend vertically from both side edges of the bottom surface 13a' toward the sliding surface 11.

[0037] In addition, the inclined groove 13' is formed with an acute angle portion 13C' formed by the wall portion 13b' and the side wall portion 13d', and an obtuse angle portion 13D' formed by the wall portion 13b' and the side wall portion 13c'.

[0038] 3, the fluid introduction groove 16 is composed of a liquid guide groove portion 17 that communicates with the outer space S2, and a Rayleigh step 18 that extends circumferentially concentrically with the stationary seal ring 10 from the inner diameter side of the liquid guide groove portion 17 toward the positive rotation direction of the rotating seal ring 20. The liquid guide groove portion 17 and the Rayleigh step 18 are formed to approximately the same depth as the depth dimension of the dynamic pressure generating groove 13. The Rayleigh step 18 is also formed so that its circumferential length is longer than the circumferential length of the liquid guide groove portion 17 and the circumferential length of one dynamic pressure generating groove 13.

[0039] 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, when rotating forward, and when rotating reverse will be described in that order.

[0040] First, when the rotating seal ring 20 is not rotating, the sealed fluid F flows into the fluid inlet groove 16. Since the stationary seal ring 10 is biased toward the rotating 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 internal space S1.

[0041] 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 outer space S2 is drawn into the liquid guide groove portion 17. That is, in the fluid introduction groove 16, the sealed fluid F moves from the liquid guide groove portion 17 toward the end portion 18A of the Rayleigh step 18 on the downstream side in the relative rotation direction, as indicated by arrow H1. Note that the flows of the sealed fluid F and the atmosphere A in Fig. 4 are shown generally without specifying the relative rotational speed of the rotating seal ring 20.

[0042] The pressure of the sealed fluid F that has moved toward the end 18A of the Rayleigh step 18 is increased at and in the vicinity of the end 18A of the Rayleigh step 18. That is, a positive pressure is generated at and in the vicinity of the end 18A of the Rayleigh step 18.

[0043] Since the depth of the Rayleigh step 18 is shallow, a positive pressure is generated at the end 18A of the Rayleigh step 18 and in its vicinity even if the rotation speed of the rotating seal ring 20 is low and the amount of movement of the sealed fluid F is small.

[0044] In addition, 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 in the fluid introduction groove 16, as indicated by the arrow H2, mainly flows between the sliding surfaces 11, 21. The presence of the sealed fluid F between the sliding surfaces 11, 21 in this manner improves lubrication even during low-speed rotation, and the wear between the sliding surfaces 11, 21 can be suppressed. Since the floating distance between the sliding surfaces 11, 21 is small, the amount of the sealed fluid F that leaks into the internal space S1 is small. In addition, since the liquid guide groove portion 17 is provided, a large amount of the sealed fluid F can be retained, and poor lubrication between the sliding surfaces 11, 21 during low-speed rotation can be avoided.

[0045] On the other hand, in the dynamic pressure generating grooves 13 and inclined 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 in the dynamic pressure generating grooves 13 and inclined 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 and inclined 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.

[0046] 4, when the relative rotational speed of the rotating seal ring 20 increases, the air A in the dynamic pressure generating grooves 13 and the inclined grooves 13' moves in the forward rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21, and the air A in the inner space S1 is drawn into the dynamic pressure generating grooves 13 and the inclined grooves 13'. That is, in the dynamic pressure generating grooves 13 and the inclined grooves 13', a large amount of air A moves from the inner diameter end 13A of the inclined groove 14 to the outer diameter side end of the inclined groove 14 and from the inner diameter end 13A' of the inclined groove 13' to the outer diameter end 13B', as shown by arrows L1 and L1'.

[0047] The pressure of the air A moving toward the outer diameter end of the inclined groove 14 is increased at and near the acute angle 13C. That is, positive pressure is generated at and near the acute angle 13C. Meanwhile, the pressure of the air A moving toward the outer diameter end 13B' of the inclined groove 13' is increased at and near the acute angle 13C'. That is, positive pressure is generated at and near the acute angle 13C'.

[0048] 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 acute angles 13C, 13C', causing the sliding surfaces 11, 21 to move further apart compared to when the speed is low. As a result, air A mainly flows into the space between the sliding surfaces 11, 21 within the dynamic pressure generating groove 13 and the inclined groove 13', as indicated by the arrows L2, L2'.

[0049] The atmosphere A in the dynamic pressure generating groove 13 and the inclined groove 13' indicated by the arrows L2, L2' acts to push the sealed fluid F near the acute angle 13C of the dynamic pressure generating groove 13 and the acute angle 13C' of the inclined groove 13' back toward the outer space S2, so that little of the sealed fluid F leaks into the dynamic pressure generating groove 13 and the inclined groove 13' or into the inner space S1.

[0050] In addition, the atmosphere A in the inclined groove 13' indicated by the arrow L2' pushes the sealed fluid F near the acute angle portion 13C' of the inclined groove 13' back to the outer space S2 side, thereby entering the Rayleigh step 18 of the fluid introduction groove 16 as indicated by the arrow H3, thereby preventing the sealed fluid F from leaking into the inner space S1.

[0051] The sliding parts of this embodiment are designed so that, during high speed forward rotation, the positive pressure generating capacity of the inclined grooves 14, 13' as a whole is sufficiently greater than the positive pressure generating capacity of the reverse inclined grooves 15 as a whole and the positive pressure generating capacity of the Rayleigh step 18 as a whole, so that ultimately, only the atmosphere A is present between the sliding surfaces 11, 21, i.e., gas lubrication is achieved.

[0052] Next, the reverse rotation of the rotating seal ring 20 will be described with reference to Fig. 5. As shown in Fig. 5, when the rotating seal ring 20 rotates in the reverse rotation 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 rotating seal ring 20 due to shear with the sliding surface 21, and enters the liquid guide groove portion 17 on the downstream side in the relative rotation direction, and a part of the sealed fluid F in the liquid guide groove portion 17 flows out to the outer space S2. Note that the flows of the sealed fluid F and the atmosphere A in Fig. 5 are shown simply and diagrammatically, without specifying the relative rotation speed of the rotating seal ring 20.

[0053] At this time, the sealed fluid F present in the land portion 12b between adjacent fluid introduction grooves 16 and in the land portion 12c between the dynamic pressure generating grooves 13 and the fluid introduction groove 16 spaced radially apart from each other is sucked into the fluid introduction groove 16 as shown by the arrow H2' due to the negative pressure generated at and near the end 18A of the Rayleigh step 18, and this tendency is particularly noticeable near the end 18A.

[0054] In this manner, when the rotating seal ring 20 rotates counterclockwise relative to the stationary seal ring 10, a large amount of the sealed fluid F sucked into the fluid introduction groove 16 is retained in the liquid guide groove portion 17, thereby preventing poor lubrication between the sliding surfaces 11, 21.

[0055] 5, the sealed fluid F that has entered the reverse inclined groove 15 formed on the outer diameter side of the dynamic pressure generating groove 13 moves in the reverse rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21. That is, in the dynamic pressure generating groove 13, the sealed fluid F moves in the reverse inclined groove 15 toward the acute angle portion 13D as shown by the arrow H3'.

[0056] The pressure of the sealed fluid F moving toward the acute angle portion 13D is increased at the acute angle portion 13D and its vicinity, that is, a positive pressure is generated at the acute angle portion 13D and its vicinity.

[0057] In addition, the force of the positive pressure generated at and near the acute angle portion 13D slightly separates the sliding surfaces 11, 21. As a result, the sealed fluid F in the fluid introduction groove 16, as indicated by the arrow H4', mainly flows between the sliding surfaces 11, 21.

[0058] The sealed fluid F flowing out from the acute angle portion 13D indicated by the arrow H4' acts to push back the sealed fluid F near the acute angle portion 13D of the dynamic pressure generating groove 13 toward the outer space S2, so that little of the sealed fluid F leaks into the dynamic pressure generating groove 13 or the inner space S1.

[0059] At this time, the sealed fluid F present around the acute angle portion 13C is sucked into the reverse inclined groove 15 as shown by the arrow H5' by the negative pressure generated at and near the acute angle portion 13C. The sealed fluid F sucked into the reverse inclined groove 15 is returned to between the sliding surfaces 11 and 21 from the acute angle portion 13D.

[0060] Furthermore, the sealed fluid F introduced into the fluid inlet groove 16 and flowing out from the vicinity of the liquid guide groove portion 17 to between the sliding surfaces 11, 21 is captured by being sucked into the reverse inclined groove 15 of the dynamic pressure generating groove 13 located downstream in the relative rotation direction of the liquid guide groove portion 17 of the fluid inlet groove 16. At this time, since negative pressure is generated at and near the acute angle portion 13C, the sealed fluid F flowing out between the sliding surfaces 11, 21 is easily sucked into the reverse inclined groove 15 of the dynamic pressure generating groove 13.

[0061] In addition, the sealed fluid F returned from the acute angle portion 13D of the dynamic pressure generating groove 13, which is located upstream of the Rayleigh step 18 of the fluid inlet groove 16 in the relative rotation direction, toward the outer diameter side between the sliding surfaces 11, 21, is sucked into the fluid inlet groove 16 as shown by arrow H2' due to the negative pressure generated at and near the end portion 18A of the Rayleigh step 18, as described above.

[0062] In this way, during reverse rotation, the reverse inclination grooves 15 of the multiple dynamic pressure generating grooves 13 are arranged between circumferentially adjacent fluid introduction grooves 16, so that the sealed fluid F is transferred between the fluid introduction groove 16 and the multiple reverse inclination grooves 15 and is retained on the outer diameter side, and therefore little of the sealed fluid F leaks into the dynamic pressure generating grooves 13 or the internal space S1.

[0063] Since the inner diameter end 13A of the inclined groove 14 is open to the inner space S1, the negative pressure generated in the inclined groove 14 during reverse rotation of the rotary seal ring 20 is small. Furthermore, since the inclined groove 14 and the reverse inclined groove 15 are continuous grooves, during reverse rotation of the rotary seal ring 20, the sealed fluid F that has entered the dynamic pressure generating groove 13 is returned between the sliding surfaces 11, 21 from the acute angle portion 13D toward the outer diameter side by the flow of the sealed fluid F in the reverse inclined groove 15, so that the amount of the sealed fluid F leaking through the inclined groove 14 into the inner space S1 can be reduced.

[0064] As described above, when the rotating seal ring 20 starts to rotate relative to the stationary seal ring 10, the sliding surfaces 11, 21 are lubricated by the sealed fluid F that flows out from the fluid introduction groove 16 to 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 groove 13 and the inclined groove 13', and wear between the sliding surfaces 11, 21 can be suppressed from the start of the relative rotation throughout the high-speed rotation.

[0065] During forward rotation of the rotary seal ring 20, the sealed fluid F that has flowed from the outer space S2 between the sliding surfaces 11, 21 is sucked in and pushed back toward the outer space S2 by the positive pressure generated mainly in the inclined grooves 14 and 13' of the dynamic pressure generating groove 13, thereby suppressing leakage of the sealed fluid F from between the sliding surfaces 11, 21 into the inner space S1. On the other hand, during reverse rotation of the rotary seal ring 20, the sealed fluid F that has entered the reverse inclined groove 15 on the outer diameter side of the inclined groove 14 of the dynamic pressure generating groove 13 moves due to shear with the sliding surface 21 of the rotary seal ring 20 and is returned to between the sliding surfaces 11, 21 from the end of the reverse inclined groove 15 on the sealed fluid F side, i.e., the acute angle portion 13D, toward the outer diameter side, thereby reducing leakage of the sealed fluid F into the inner space S1. In this way, the dynamic pressure generating groove 13 has the inclined groove 14 and the reverse inclined groove 15 which have different rotational directions for generating the main dynamic pressure, so that the sliding surfaces 11, 21 can be separated from each other during both rotations to suppress wear, and leakage of the sealed fluid F from between the sliding surfaces 11, 21 into the internal space S1 can be suppressed.

[0066] Furthermore, during reverse rotation, the sealed fluid F which is introduced into the fluid inlet groove 16 and flows out from the vicinity of the liquid guide groove portion 17 to between the sliding surfaces 11, 21 is sucked into the reverse inclined groove 15 of the dynamic pressure generating groove 13 by the negative pressure generated at and in the vicinity of the acute angle portion 13C of the dynamic pressure generating groove 13 located downstream of the liquid guide groove portion 17 of the fluid inlet groove 16 in the relative rotation direction, and is captured. The sealed fluid F captured in the reverse inclined groove 15 moves due to shear with the sliding surface 21 of the rotating seal ring 20 and is returned from the acute angle portion 13D of the reverse inclined groove 15 toward the outer diameter side to between the sliding surfaces 11, 21, thereby further reducing leakage of the sealed fluid F into the internal space S1.

[0067] In addition, since the dynamic pressure generating groove 13 is formed in an L-shape by the inclined groove 14 and the reverse inclined groove 15, during forward rotation, the sealed fluid F sucked into the reverse inclined groove 15 from the acute angle portion 13D together with the air A sucked into the inclined groove 14 from the inner diameter end 13A can be collected at the acute angle portion 13C to generate positive pressure. During reverse rotation, the sealed fluid F can be pushed back to the outer space S2 by the dynamic pressure generated in the reverse inclined groove 15, so that the intrusion of the sealed fluid F into the inclined groove 14 can be suppressed and the leakage of the sealed fluid F into the inner space S1 through the inclined groove 14 can be suppressed.

[0068] Furthermore, the reverse inclined grooves 15 have a shorter extension distance than the inclined grooves 14. This allows the reverse inclined grooves 15 to generate positive pressure early during reverse rotation.

[0069] Moreover, the reverse inclined groove 15 is a groove having an acute angle portion 13D tapered toward the outer diameter side end portion. According to this, during reverse rotation, the sealed fluid F in the reverse inclined groove 15 is concentrated at the acute angle portion 13D to easily generate positive pressure, thereby enhancing the dynamic pressure effect.

[0070] Moreover, the reverse inclined grooves 15 are provided only in the dynamic pressure generating grooves 13 formed between adjacent fluid introduction grooves 16. With this, the reverse inclined grooves 15 are not present at positions radially overlapping with the inclined grooves 13' arranged on the inner diameter side of the fluid introduction grooves 16, and the extension distance of the inclined grooves 13' arranged on the inner diameter side of the fluid introduction grooves 16 can be increased. Therefore, during forward rotation, it becomes easier to generate a high positive pressure by the atmosphere A in the inclined grooves 13', and the dynamic pressure effect can be enhanced.

[0071] In addition, the inclined grooves 14, 13' communicate with the internal space S1. With this, during forward rotation, the atmosphere A in the internal space S1 is easily introduced from the inner diameter ends 13A, 13A' into the inclined grooves 14, 13', and a positive pressure is easily generated by the atmosphere A in the inclined grooves 14, 13', thereby enhancing the dynamic pressure effect.

[0072] Moreover, the fluid introduction groove 16 is provided with a Rayleigh step 18. According to this, during forward rotation, the Rayleigh step 18 generates dynamic pressure to slightly separate the sliding surfaces 11, 21, and allows the sealed fluid F to be introduced between the sliding surfaces 11, 21, thereby improving the lubrication between the sliding surfaces 11, 21. Moreover, since the liquid guide groove portion 17 of the fluid introduction groove 16 communicates with the external space S2, it is easy to introduce the sealed fluid F into the liquid guide groove portion 17, and positive pressure can be generated by the Rayleigh step 18 at an early stage.

[0073] In addition, during reverse rotation, the Rayleigh step 18 can suck in the sealed fluid F around the end 18A by negative pressure and introduce it into the liquid guide groove portion 17, thereby suppressing leakage of the sealed fluid F into the internal space S1.

[0074] 6, a stationary seal ring 110 as a sliding part may have a sliding surface 111 in which a plurality of fluid introduction grooves 116 are uniformly arranged in the circumferential direction on the inner diameter side, and a plurality of dynamic pressure generating grooves 113 and inclined grooves 113' are uniformly arranged in the circumferential direction on the outer diameter side, so that the stationary seal ring 10 may be applied to an outside-type mechanical seal that seals the sealed fluid F that tends to leak from the inner diameter side to the outer diameter side of the sliding surface 111. The dynamic pressure generating grooves 113, inclined grooves 113' and fluid introduction grooves 116 are formed by inverting the dynamic pressure generating grooves 13, inclined grooves 13' and fluid introduction grooves 16 in the first embodiment.

[0075] The arrangement of the dynamic pressure generating grooves and the fluid introduction grooves in this modified example can also be applied to the sliding surfaces of the sliding components in the following embodiments. That is, the radial arrangement of the dynamic pressure generating grooves and the fluid introduction grooves in the following embodiments can be interchanged to apply to an outside-type mechanical seal. EXAMPLES

[0076] Next, a sliding component according to a second embodiment will be described with reference to Fig. 7. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0077] 7, in the sliding surface 211 of the stationary seal ring 210 of the second embodiment, the dynamic pressure generating groove 213, whose outer diameter end 213B is arranged between the fluid introduction grooves 16 adjacent in the circumferential direction, has the same configuration as the dynamic pressure generating groove 13 of the first embodiment. Also, the dynamic pressure generating groove 213', whose outer diameter end 213B' is arranged on the inner diameter side of the fluid introduction groove 16, is made up of an inclined groove 214' that extends from the inner diameter side toward the outer diameter side and generates dynamic pressure, and an inverse inclined groove 215' that is formed continuously with the outer diameter side of the inclined groove 214', extends in the opposite direction to the inclined groove 214', and generates dynamic pressure, forming an L shape.

[0078] The extension distance of the reverse inclined groove 215' is shorter than that of the inclined groove 214'. Moreover, the extension distances of the inclined groove 214' and the reverse inclined groove 215' are shorter than the extension distances of the inclined groove 214 and the reverse inclined groove 215 constituting the dynamic pressure generating groove 213, respectively.

[0079] According to this, during forward rotation, the sealed fluid F sucked into the dynamic pressure generating groove 213' around the inclined groove 214' and the inverse inclined groove 215' on the inner diameter side of the fluid introduction groove 16 as in the dynamic pressure generating groove 213 is returned from the acute angle portion 213C' toward the outer diameter side between the sliding surfaces 211, 21 and pushed back to the outer space S2. During reverse rotation, the sealed fluid F flowing out from the acute angle portion 213D' pushes back the sealed fluid F near the acute angle portion 213D' to the outer space S2, thereby entering the Rayleigh step 18 of the fluid introduction groove 16. Therefore, during both rotations, the sliding surfaces 211, 21 can be separated from each other to suppress wear, and leakage of the sealed fluid F from between the sliding surfaces 211, 21 into the inner space S1 can be further suppressed. EXAMPLES

[0080] Next, a sliding component according to a third embodiment will be described with reference to Fig. 8 to Fig. 10. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0081] As shown in FIG. 8, in the sliding surface 311 of the stationary seal ring 310 of the third embodiment, the inclined groove 313', whose outer diameter end 313B' is disposed on the inner diameter side of the fluid introduction groove 16, has the same configuration as the inclined groove 13' of the first embodiment. The dynamic pressure generating groove 313 is composed of an inclined groove 314 that extends from the inner diameter side toward the outer diameter side and generates dynamic pressure, and a reverse inclined groove 315 that is radially spaced on the outer diameter side of the inclined groove 314, extends in the opposite direction to the inclined groove 314, and serves as a recess that generates dynamic pressure. That is, the dynamic pressure generating groove 313 is configured such that the inclined groove 314 and the reverse inclined groove 315 are radially separated by an annular land portion 312d described later. The reverse inclined groove 315 is disposed in the land portion 312b between the fluid introduction grooves 16 adjacent in the circumferential direction.

[0082] In detail, the inclined groove 314 has an inner diameter end 314A that communicates with the inner space S1 and extends in an arc shape from the inner diameter end 314A toward the outer diameter side while inclining in the forward rotation direction of the rotating seal ring 20, and the straight outer diameter end 314B of the inclined groove 314 is closed so as to be non-communicating with the reverse inclined groove 315.

[0083] The reverse inclined groove 315 has an approximate parallelogram shape and extends linearly from the inner diameter end 315A toward the outer diameter side while inclining in the reverse rotation direction of the rotating seal ring 20, and the outer diameter end 315B is closed so as to be non-communicating with the outer space S2.

[0084] In addition, an annular land portion 312d that is continuous in the circumferential direction and has a predetermined or greater width in the radial direction is formed between the inclined groove 314 and the inversely inclined groove 315. The annular land portion 312d, like the other land portions, is also disposed on the same plane and constitutes the flat surface of the land 312.

[0085] Further, inclined groove 314, acute angle portion 314C formed by wall portion 314b and side wall portion 314d at outer diameter end 314B, and obtuse angle portion 314D formed by wall portion 314b and side wall portion 314c are formed.

[0086] In addition, reverse inclined groove 315 is formed with acute angle 315C formed by wall portion 315b and side wall portion 315d at inner diameter end 315A, and acute angle 315D formed by wall portion 315e and side wall portion 315c at linear outer diameter end 315B, and acute angle portion 315D is located on the outer diameter side of acute angle portion 315C and downstream in the reverse rotation direction of rotating seal ring 20.

[0087] The extension distance of the reverse inclination groove 315 is shorter than the extension distance of the inclination groove 314. The depth of the reverse inclination groove 315 is the same as the depth of the inclination groove 314. Note that the reverse inclination groove 315 may be formed to a different depth from the inclination groove 314.

[0088] Further, outer diameter end 314B and inner diameter end 315A are arranged in a position where they are substantially parallel and have substantially the same length and overlap in the radial direction. From the viewpoint of preventing leakage, it is preferable that inner diameter end 315A is arranged in a position where it is longer than outer diameter end 314B and overlaps in the radial direction.

[0089] Next, the operation of the stationary seal ring 310 and the rotating seal ring 20 during relative rotation will be described with reference to Figures 9 and 10. Note that the movement of the fluid in the fluid introduction groove 16 and the inclined groove 313' is substantially the same as in the first embodiment, so in this embodiment, the movement of the fluid in the inclined groove 314 and the reverse inclined groove 315 constituting the dynamic pressure generating groove 313 will be mainly described.

[0090] In the dynamic pressure generating groove 313, when the relative rotation speed in the forward rotation direction between the rotating seal ring 20 and the stationary seal ring 310 is low, the atmosphere A does not become sufficiently dense in the inclined groove 314 and high positive pressure is not generated. Also, since the extending distance of the reverse inclined groove 315 is short, high positive pressure is not generated even if the sealed fluid F penetrates into the reverse inclined groove 315.

[0091] 9, when the relative rotation speed of the rotating seal ring 20 increases, the atmosphere A in the inclined groove 314 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 inner space S1 is drawn into the inclined groove 314. That is, in the inclined groove 314, a large amount of atmosphere A moves from the inner diameter end 314A of the inclined groove 314 toward the outer diameter end 314B, as shown by arrow L1.

[0092] The pressure of the atmosphere A moving toward the outer diameter end 314B of the inclined groove 314 is increased at the acute angle portion 314C and its vicinity. That is, a positive pressure is generated at the acute angle portion 314C and its vicinity.

[0093] Furthermore, the atmosphere A in the inclined groove 314 indicated by the arrow L2 acts to push back the sealed fluid F near the acute angle portion 314C toward the outer space S2, so that little of the sealed fluid F leaks into the inclined groove 314 or the inner space S1.

[0094] On the other hand, in the reverse inclined groove 315, the sealed fluid F that has entered the reverse inclined groove 315 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 vicinity of the acute angle portion 315D is drawn into the reverse inclined groove 315. That is, in the reverse inclined groove 315, the sealed fluid F moves from the acute angle portion 315D of the reverse inclined groove 315 toward the acute angle portion 315C as shown by the arrow H5, and the pressure is increased at and in the vicinity of the acute angle portion 315C. That is, a positive pressure is generated at and in the vicinity of the acute angle portion 315C.

[0095] Further, the sealed fluid F in the inclined groove 315 indicated by the arrow H6 is pushed back into the outer space S2 by the atmosphere A in the inclined groove 314 indicated by the arrow L2 together with the sealed fluid F in the vicinity of the acute angle portion 315C.

[0096] Next, the reverse rotation of the rotary seal ring 20 will be described with reference to Fig. 10. As shown in Fig. 10, the sealed fluid F that has entered the reverse inclined groove 315 formed on the outer diameter side of the inclined groove 314 moves in the reverse rotation direction of the rotary seal ring 20 due to shearing with the sliding surface 21, and the sealed fluid F in the vicinity of the acute angle portion 315C is drawn into the reverse inclined groove 315. That is, in the reverse inclined groove 315, the sealed fluid F moves from the acute angle portion 315C of the reverse inclined groove 315 toward the acute angle portion 315D as shown by the arrow H3', and the pressure is increased at the acute angle portion 315D and its vicinity. That is, a positive pressure is generated at the acute angle portion 315D and its vicinity.

[0097] The sealed fluid F in the reverse inclined groove 315 indicated by the arrow H4' acts to push back the sealed fluid F near the acute angle portion 315D of the reverse inclined groove 315 toward the outer space S2, so that little of the sealed fluid F leaks into the inclined groove 314 or the inner space S1.

[0098] At this time, the sealed fluid F present around the acute angle portion 315C is sucked into the reverse inclined groove 315 as shown by the arrow H5' by the negative pressure generated at and near the acute angle portion 315C. The sealed fluid F sucked into the reverse inclined groove 315 is returned between the sliding surfaces 311, 21 from the acute angle portion 315D toward the outer diameter side.

[0099] Furthermore, the sealed fluid F introduced into the fluid inlet groove 16 and flowing out from the vicinity of the liquid guide groove portion 17 to between the sliding surfaces 311, 21 is captured by being sucked into the reverse inclined groove 315 of the dynamic pressure generating groove 313 located downstream in the relative rotation direction of the liquid guide groove portion 17 of the fluid inlet groove 16. At this time, since negative pressure is generated at and near the acute angle portion 315C, the sealed fluid F flowing out between the sliding surfaces 311, 21 is easily sucked into the reverse inclined groove 315 of the dynamic pressure generating groove 313.

[0100] In addition, the sealed fluid F returned between the sliding surfaces 311, 21 toward the outer diameter side from the acute angle portion 315D of the inverted inclined groove 315 of the dynamic pressure generating groove 313 located upstream of the Rayleigh step 18 of the fluid introduction groove 16 in the relative rotation direction is sucked into the fluid introduction groove 16 as shown by arrow H2' due to the negative pressure generated at and near the end 18A of the Rayleigh step 18, as described above.

[0101] In this way, during reverse rotation, the reverse inclined grooves 315 of the multiple dynamic pressure generating grooves 313 are arranged between circumferentially adjacent fluid introduction grooves 16, so that the sealed fluid F is transferred between the fluid introduction groove 16 and the multiple reverse inclined grooves 315 and is retained on the outer diameter side, and therefore little of the sealed fluid F leaks into the dynamic pressure generating grooves 313 or the internal space S1.

[0102] As described above, during forward rotation of the rotary seal ring 20, the sealed fluid F that has flowed from the outer space S2 between the sliding surfaces 311, 21 is sucked in and pushed back toward the outer space S2 by the positive pressures generated in the inclined groove 314 and the reverse inclined groove 315 of the dynamic pressure generating groove 313, thereby suppressing leakage of the sealed fluid F from between the sliding surfaces 311, 21 into the inner space S1. On the other hand, during reverse rotation of the rotary seal ring 20, the sealed fluid F that has entered the reverse inclined groove 315 on the outer diameter side of the inclined groove 314 follows and moves due to shear with the sliding surface 21 of the rotary seal ring 20, and is returned to between the sliding surfaces 311, 21 from the end of the reverse inclined groove 315 on the sealed fluid F side, i.e., the acute angle portion 315D, toward the outer diameter side, thereby reducing leakage of the sealed fluid F into the inner space S1. In this way, the dynamic pressure generating groove 313 has the inclined groove 314 and the reverse inclined groove 315 which have different rotational directions for generating dynamic pressure mainly, so that the sliding surfaces 311, 21 can be separated from each other during both rotations to suppress wear, and leakage of the sealed fluid F from between the sliding surfaces 311, 21 into the internal space S1 can be suppressed.

[0103] Furthermore, during reverse rotation, the sealed fluid F introduced into the fluid introduction groove 16 and flowing out from the vicinity of the liquid guide groove portion 17 to between the sliding surfaces 311, 21 is sucked into and captured by the reverse inclined groove 315 of the dynamic pressure generating groove 313 located downstream of the liquid guide groove portion 17 of the fluid introduction groove 16 in the relative rotation direction. At this time, negative pressure is generated at and near the acute angle portion 315C, so that the sealed fluid F flowing out between the sliding surfaces 311, 21 is easily sucked into the reverse inclined groove 315 of the dynamic pressure generating groove 313. Furthermore, the sealed fluid F captured in the reverse inclined groove 315 moves following the shear with the sliding surface 21 of the rotary seal ring 20 and is returned from the acute angle portion 315D of the reverse inclined groove 315 toward the outer diameter side to between the sliding surfaces 311, 21, thereby further reducing leakage of the sealed fluid F into the inner space S1.

[0104] In addition, an annular land portion 312d that is circumferentially continuous and has a radial width of a predetermined value or more is formed between the inclined groove 314 and the reverse inclined groove 315. Since the inclined groove 314 and the reverse inclined groove 315 are separated by this annular land portion 312d, during reverse rotation of the rotating seal ring 20, the sealed fluid F is sucked into the reverse inclined groove 315 from the acute angle portion 315C on the outer diameter side of the annular land portion 312d and captured. This prevents the sealed fluid F from passing over the annular land portion 312d and entering the inclined groove 314, and further reduces the amount of sealed fluid F leaking into the internal space S1 through the inclined groove 314.

[0105] In addition, since the inclined groove 314 and the reverse inclined groove 315 are separated by the annular land portion 312d, the inclined groove 314 and the reverse inclined groove 315 do not interfere with each other's dynamic pressure generation during both rotations, making it easier to exert the dynamic pressure effect.

[0106] In addition, the radial center of the annular land portion 312d separating the inclined groove 314 and the reverse inclined groove 315 is disposed closer to the sealed fluid F than the radial center of the sliding surface 311. This ensures a long extension distance of the inclined groove 314, and the inclined groove 314 becomes a more major source of dynamic pressure than the reverse inclined groove 315 during forward rotation, thereby further suppressing leakage of the sealed fluid F into the internal space S1.

[0107] Incidentally, the inclined groove 313' is not limited to having the same configuration as the inclined groove 13' in the first embodiment, and may have the same configuration as the dynamic pressure generating groove 213' in the second embodiment, for example, or may have a configuration in which the inclined groove and the inverted inclined groove are separated in the radial direction, similar to the dynamic pressure generating groove 313. Furthermore, such changes in the configuration of the dynamic pressure generating groove can also be applied to the sliding surfaces of the sliding components in each of the following embodiments. EXAMPLES

[0108] Next, a sliding component according to a fourth embodiment will be described with reference to Fig. 11. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0109] As shown in FIG. 11, in the sliding surface 411 of the stationary seal ring 410 of this embodiment 4, the dynamic pressure generating groove 413 is composed of an inclined groove 414 that extends from the inner diameter side toward the outer diameter side and generates dynamic pressure, and a recess 415 that is radially spaced apart on the outer diameter side of this inclined groove 414.

[0110] The recess 415 has a substantially square shape and is disposed in the approximate circumferential center of the outer diameter end 414B of the inclined groove 414 in the land portion 412b between circumferentially adjacent fluid introduction grooves 16. The recess 415 is disposed at radially opposing corners, i.e., the diagonal lines are disposed on the radial lines of the stationary seal ring 410.

[0111] According to this, during reverse rotation, the sealed fluid F flowing out from the fluid introduction groove 16 to between the sliding surfaces 411, 21 is captured by the recess 415 on the downstream side of the relative rotation of the fluid introduction groove 16, thereby reducing leakage of the sealed fluid F into the internal space S1.

[0112] Furthermore, as long as the recess 415 does not have a directional shape in the circumferential direction extending from upstream to downstream during relative rotation like the reverse inclined groove 315 of Example 3, the shape is not limited to being approximately square, and may be freely configured, for example, circular or triangular. EXAMPLES

[0113] Next, a sliding component according to a fifth embodiment will be described with reference to Fig. 12. Note that a description of the same configuration as in the above-mentioned embodiment will be omitted.

[0114] As shown in FIG. 12, the fluid introduction groove 516 in the stationary seal ring 510 of this embodiment 5 is composed of a liquid guide groove portion 517 that communicates with the outer space S2, and Rayleigh steps 518, 518' that extend circumferentially concentrically with the stationary seal ring 510 from the inner diameter side of the liquid guide groove portion 517 toward the forward rotation direction and reverse rotation direction of the rotating seal ring 20, respectively.

[0115] According to this, during forward rotation of the rotating seal ring 20, the sealed fluid F in the fluid introduction groove 516 moves in the forward rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21, moving from the liquid guide groove portion 517 to the Rayleigh step 518 side, and the sealed fluid F in the outer space S2 is drawn into the liquid guide groove portion 517. Also during reverse rotation, the sealed fluid F in the fluid introduction groove 516 moves in the reverse rotation direction of the rotating seal ring 20 due to shear with the sliding surface 21, moving from the liquid guide groove portion 517 to the Rayleigh step 518' side, and the sealed fluid F in the outer space S2 is drawn into the liquid guide groove portion 517.

[0116] In this way, during both rotations, the fluid introduction groove 516 generates dynamic pressure through the Rayleigh steps 518, 518', slightly separating the sliding surfaces 511, 21 and supplying the sealed fluid F between the sliding surfaces 511, 21, thereby increasing the lubrication between the sliding surfaces 511, 21. EXAMPLES

[0117] Sixth embodiment Next, a sliding component according to a sixth embodiment will be described with reference to Fig. 13. Note that a description of the same configuration as in the above-mentioned embodiment will be omitted.

[0118] 13, the fluid introduction groove 616 in the stationary seal ring 610 of the sixth embodiment has the same configuration as the fluid introduction groove 516 of the fifth embodiment. Also, the dynamic pressure generating groove 613 has the same configuration as the dynamic pressure generating groove 313 of the third embodiment.

[0119] According to this, the fluid introduction groove 616 slightly separates the sliding surfaces 611, 21 during both rotations and introduces the sealed fluid F between the sliding surfaces 611, 21, thereby further suppressing wear between the sliding surfaces 611, 21, and also suppressing leakage of the sealed fluid F by the inclined grooves 614 and the reverse inclined grooves 615 which are radially separated in the dynamic pressure generating groove 613. EXAMPLES

[0120] Next, a sliding component according to a seventh embodiment will be described with reference to Fig. 14. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0121] As shown in FIG. 14, the fluid introduction groove 716 in the stationary seal ring 710 of the seventh embodiment is configured as a groove having a substantially trapezoidal shape that communicates with the outer space S2.

[0122] In detail, the fluid introduction groove 716 has a side wall portion 716a on the downstream side in the forward rotation direction of the rotary seal ring 20 extending linearly while inclining in the reverse rotation direction from the outer diameter side toward the inner diameter side, and a side wall portion 716d on the upstream side in the forward rotation direction of the rotary seal ring 20 extending linearly along a radial line from the outer diameter side toward the inner diameter side. Also, the fluid introduction groove 716 has an acute angle portion 716A formed by a wall portion 716c and a side wall portion 716b at the inner diameter end, which is disposed circumferentially close to an acute angle portion 713C of the dynamic pressure generating groove 713 on the downstream side in the forward rotation direction.

[0123] According to this, since the side wall portion 716a of the fluid introduction groove 716 is inclined along the circumferential direction, the sealed fluid F is easily introduced into the fluid introduction groove 716 when the relative rotation between the stationary seal ring 710 and the rotating seal ring 20 begins during forward rotation of the rotating seal ring 20.

[0124] Furthermore, since the acute angle portion 716A of the fluid introduction groove 716 is circumferentially close to the acute angle portion 713C of the dynamic pressure generating groove 713, during reverse rotation of the rotating seal ring 20, the sealed fluid F that leaks out in a concentrated manner from the acute angle portion 716A of the fluid introduction groove 716 can be sucked in and recovered by the negative pressure generated at and in the vicinity of the acute angle portion 713C of the dynamic pressure generating groove 713, thereby further suppressing leakage of the sealed fluid F into the internal space S1. EXAMPLES

[0125] Next, a sliding component according to an eighth embodiment will be described with reference to Fig. 15. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0126] As shown in FIG. 15, the fluid introduction groove 816 in the stationary seal ring 810 of the eighth embodiment is formed of a rectangular groove that communicates with the outer space S2.

[0127] More specifically, the fluid introduction groove 816 extends linearly while inclining in the reverse rotation direction from the outer diameter side toward the inner diameter side, with a side wall portion 816a on the downstream side in the forward rotation direction of the rotating seal ring 20 and a side wall portion 816b on the upstream side in the forward rotation direction. Also, the fluid introduction groove 816 has an acute angle portion 816A formed by a wall portion 816c and the side wall portion 816b at the inner diameter end, which is disposed circumferentially close to an acute angle portion 813C of the dynamic pressure generating groove 813 on the downstream side in the forward rotation direction.

[0128] According to this, since the side wall portions 816a, 816b of the fluid introduction groove 816 are each inclined along the circumferential direction, the sealed fluid F is more easily introduced into the fluid introduction groove 816 when the relative rotation between the stationary seal ring 810 and the rotating seal ring 20 begins during forward rotation of the rotating seal ring 20.

[0129] Furthermore, since the angle of the acute angle portion 816A of the fluid introduction groove 816 is smaller than that of the seventh embodiment and is circumferentially closer to the acute angle portion 813C of the dynamic pressure generating groove 813, during reverse rotation of the rotating seal ring 20, the sealed fluid F is likely to concentrate at the acute angle portion 816A. The sealed fluid F that concentrates and leaks out from the acute angle portion 816A of the fluid introduction groove 816 can be sucked in and recovered by the negative pressure generated at and in the vicinity of the acute angle portion 813C of the dynamic pressure generating groove 813, thereby further suppressing leakage of the sealed fluid F into the internal space S1. EXAMPLES

[0130] Next, a sliding component according to a ninth embodiment will be described with reference to Fig. 16. Note that a description of the same configuration as in the above embodiment will be omitted.

[0131] 16, the fluid introduction groove 916 in the stationary seal ring 910 of the ninth embodiment is composed of a liquid guide groove portion 917 that communicates with the outer space S2, and a Rayleigh step 918 that extends circumferentially concentrically with the stationary seal ring 910 from the outer diameter side of the liquid guide groove portion 917 toward the positive rotation direction of the rotating seal ring 20. The liquid guide groove portion 917 has approximately the same shape as the fluid introduction groove 916 of the eighth embodiment.

[0132] According to this, since the fluid introduction groove 916 is provided with a Rayleigh step 918, during forward rotation, the Rayleigh step 918 generates dynamic pressure to slightly separate the sliding surfaces 911, 21 and supply the sealed fluid F between the sliding surfaces 911, 21, thereby increasing the lubrication between the sliding surfaces 911, 21. EXAMPLES

[0133] Next, a sliding component according to a tenth embodiment will be described with reference to Fig. 17. Note that a description of the same configuration as in the previous embodiment will be omitted.

[0134] 17, the fluid introduction groove 1016 in the stationary seal ring 1010 of this embodiment 10 is composed of a liquid guide groove portion 1017 that communicates with the outer space S2, and Rayleigh steps 1018, 1018' that extend circumferentially concentrically with the stationary seal ring 1010 from the inner diameter side of the liquid guide groove portion 1017 toward the forward rotation direction and reverse rotation direction of the rotating seal ring 20, respectively. The liquid guide groove portion 1017 has approximately the same shape as the fluid introduction groove 816 of the eighth embodiment.

[0135] According to this, during both rotations, dynamic pressure is generated by the Rayleigh steps 1018, 1018' to slightly separate the sliding surfaces 1011, 21 and supply the sealed fluid F between the sliding surfaces 1011, 21, thereby increasing the lubrication between the sliding surfaces 1011, 21.

[0136] 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.

[0137] For example, in the above embodiment, a mechanical seal for an automobile is used as an example of the sliding part, but the sliding part may be another mechanical seal for general industrial machines, etc. Also, the sliding part is not limited to a mechanical seal, and may be a sliding bearing or other sliding part other than a mechanical seal.

[0138] In the above embodiment, the dynamic pressure generating grooves and the fluid introduction grooves are provided in the stationary seal ring. However, the dynamic pressure generating grooves and the fluid introduction grooves may be provided in the rotary seal ring.

[0139] In addition, although the sealed fluid side has been described as the high pressure side and the leakage side as the low pressure side, 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.

[0140] Also, although it has been described that the inclined grooves in the dynamic pressure generating grooves communicate with the internal space S1, the present invention is not limited to this and does not necessarily have to communicate with the internal space S1 as long as dynamic pressure can be generated.

[0141] Furthermore, the dynamic pressure generating groove is not limited to a groove in which the inverted groove is continuously formed at the outer diameter side end of the inclined groove, but may be a groove in which the inverted groove branches out from approximately the center in the extension direction of the inclined groove.

[0142] Furthermore, the dynamic pressure generating groove may be such that a plurality of reverse inclined grooves are arranged for one inclined groove.

[0143] Further, the inclined groove is not limited to extending in an arc shape while inclining in the circumferential direction, and may be formed in a straight line to simplify the shape.

[0144] Also, although the dynamic pressure generating grooves and the fluid introduction grooves have been described as being approximately the same depth, the fluid introduction grooves may be deeper than the dynamic pressure generating grooves.

[0145] In the present embodiment, the sealed fluid F is described as a high-pressure liquid, but it is not limited thereto and may be a gas or a low-pressure liquid, or may be a mist of a mixture of liquid and gas.

[0146] In addition, in this embodiment, the fluid on the leaking side is described as atmosphere A, 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]

[0147] 10. Static seal ring (sliding part) 11 Sliding surface 12 Rand 12a~12c Land section 13 Dynamic pressure generating groove 13' inclined groove 13C, 13C', 13D acute angle 14 Slant groove 15 Reverse inclined groove (recess) 16 Fluid introduction groove 17 Liquid guide groove 18 Rayleigh Step 20 Rotating seal ring (other sliding parts) 21 Sliding surface 310 Static seal ring (sliding part) 311 Sliding surface 312d Circular land section 313 Dynamic pressure generating groove 313' inclined groove 314 Slant groove 314C Sharp corner 315 Reverse inclined groove (recess) 315C, 315D Sharp corners 410 Static seal ring (sliding part) 411 Sliding surface 413 Dynamic pressure generating groove 414 Slant groove 415 Recess A. Atmosphere F Sealed fluid S1 inner space S2 outside space

Claims

1. An annular sliding component is disposed at a relative rotating portion of a rotary machine, slides relative to another sliding component, and has a plurality of fluid introduction grooves on a sliding surface which communicate with a space on a sealed fluid side and introduce the sealed fluid, and a plurality of inclined grooves which extend from a leakage side to the sealed fluid side and generate dynamic pressure, The sliding surface of the sliding component is provided with recesses which are disposed at least between adjacent ones of the fluid introduction grooves in the circumferential direction and which do not communicate with a space on the sealed fluid side.

2. 2. The sliding component according to claim 1, wherein the recess is an inverted inclined groove that is provided on a sealed fluid side of the inclined groove, extends in a direction opposite to the inclined groove, and generates dynamic pressure.

3. 3. The sliding component according to claim 1, wherein the recesses are provided only between adjacent ones of the fluid introduction grooves.

4. 4. The sliding component according to claim 1, wherein the fluid introduction groove has a Rayleigh step.

5. 4. The sliding component according to claim 1, wherein the fluid introduction groove has a Rayleigh step extending on both sides in the circumferential direction.

6. The sliding component according to claim 2 , wherein the reverse inclination groove has an extension distance shorter than that of the inclination groove.

7. 7. The sliding component according to claim 2, wherein the inclined groove and the inversely inclined groove are continuous grooves.

8. 7. The sliding component according to claim 2 or 6, wherein an annular land portion is provided between the inclined groove and the reverse inclined groove, the annular land portion being continuous in the circumferential direction on the sealed fluid side of the inclined groove and having a width equal to or greater than a predetermined width in the radial direction.

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