sliding member

Abstract

Provided is a sliding member that can reliably generate negative pressure in a shallow groove regardless of the relative rotational speed of another sliding member. A sliding member (10) is annular, is disposed at a relative rotation site of a rotating machine, and slides against another sliding member (20), wherein a shallow groove (9) for generating negative pressure that extends in the circumferential direction and a deep groove (15) that is deeper than the shallow groove (9) and recovers sealed fluid (F) in the shallow groove (9) are provided on a sliding surface (11) of the sliding member (10), and the shallow groove (9) has a terminal portion (9b) in which the flow path cross-sectional area narrows toward the deep groove (15).

Description

TECHNICAL FIELD

[0001] The present application relates to a sliding member of relative rotation, for example, a sliding member used in a shaft seal device that seals a rotating shaft of a rotating machine of an automobile, a general industrial machine, or the like, or a sliding member used in a bearing of a machine of an automobile, a general industrial machine, or the like. BACKGROUND

[0002] As a shaft seal device that prevents leakage of a sealed fluid, for example, a mechanical seal has a pair of annular sliding members that relatively rotate and whose sliding surfaces slide against each other. In such a mechanical seal, in recent years, it is desired to reduce energy lost due to sliding for environmental countermeasures and the like. Therefore, for example, a positive pressure generating groove that communicates with an outer diameter side of the sealed fluid side that is high pressure and that has one end closed on the sliding surface is provided on the sliding surface of the sliding member. Thereby, when the sliding members relatively rotate, positive pressure is generated in the positive pressure generating groove to separate the sliding surfaces from each other, and the sealed fluid is introduced from the outer diameter side into the positive pressure generating groove to retain the sealed fluid, whereby lubricity is improved, and low friction is achieved.

[0003] Moreover, in order to maintain sealing for a long period of time, in addition to "lubrication", the mechanical seal is required to have such a condition of "sealing". For example, in the mechanical seal shown in Patent Document 1, a Rayleigh step and a reverse Rayleigh step that communicate with the sealed fluid side are provided on one sliding member. Thereby, when the sliding members relatively rotate, positive pressure is generated between the sliding surfaces by the Rayleigh step, the sliding surfaces are separated from each other, the sealed fluid is interposed between the sliding surfaces, whereby lubricity is improved. On the other hand, negative pressure is relatively generated in the reverse Rayleigh step, and since the reverse Rayleigh step is disposed at a position closer to the leakage side than the Rayleigh step, the sealed fluid that flows out to between the sliding surfaces from the Rayleigh step can be sucked into the reverse Rayleigh step. In addition, a deep groove that has a larger volume than the reverse Rayleigh step is provided on the relative rotation terminal side of the reverse Rayleigh step, and the sealed fluid recovered in the reverse Rayleigh step is returned to the sealed fluid side via the deep groove. In this way, leakage of the sealed fluid between the pair of sliding members to the leakage side is prevented, and sealing is improved.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENT

[0006] Patent Document 1: International Publication No. 2012 / 046749 (pages 14-16, Figure 1 ) SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In the sliding member of Patent Literature 1, the sealed fluid in the reverse Rayleigh step provided in one sliding member moves from the reverse Rayleigh step to the deep groove due to the relative rotation of the other sliding member. However, since the flow path cross-sectional area of the reverse Rayleigh step is constant in the circumferential direction, the amount of movement of the sealed fluid from the reverse Rayleigh step toward the deep groove is governed by the relative rotation speed of the sliding members, and particularly when the sliding members are rotated at a speed equal to or higher than a certain speed, although the sealed fluid on the upper side of the reverse Rayleigh step follows the movement of the other sliding member, the sealed fluid on the bottom surface side is difficult to follow the movement of the other sliding member, and the amount of movement of the sealed fluid in the reverse Rayleigh step does not increase as the relative rotation speed increases, and it can be impossible to generate sufficient negative pressure in the reverse Rayleigh step.

[0009] The present application has been made in view of such problems, and has an object to provide a sliding member capable of reliably generating negative pressure in a shallow groove regardless of the relative rotation speed of the other sliding member.

[0010] Means for solving the problems

[0011] To solve the above problems, the sliding member of the present application is annular, is disposed at a portion that relatively rotates in a rotary machine, and relatively slides with the other sliding member, wherein a shallow groove for generating negative pressure and a deep groove deeper than the shallow groove for recovering the sealed fluid in the shallow groove are provided on the sliding surface of the sliding member so as to extend in the circumferential direction, and the shallow groove has a terminal portion in which the flow path cross-sectional area narrows toward the deep groove.

[0012] Thus, since the flow path cross-sectional area of the terminal portion of the shallow groove narrows toward the deep groove, the pressure of the sealed fluid in the shallow groove increases at the terminal portion when the sliding member relatively rotates, and the sealed fluid of the terminal portion easily flows into the deep groove since the deep groove is disposed on the downstream side. In this way, negative pressure can be reliably generated in the shallow groove regardless of the rotation speed of the sliding member. Further, since the sealed fluid of the terminal portion of the shallow groove flows into the deep groove, the generation of positive pressure between the sliding surfaces due to the shallow groove can be suppressed.

[0013] It can also be that the terminal portion of the shallow groove gradually becomes shallower toward the deep groove.

[0014] Thus, the sealed fluid is gathered from the bottom surface of the shallow groove toward the sliding surface in a range from the terminal portion of the shallow groove to the deep groove, and is therefore easily affected by the tendency of the sliding surface, and thus the sealed fluid can be caused to flow into the deep groove in a large amount.

[0015] It can also be that the bottom surface of the terminal portion of the shallow groove is curved so as to be recessed toward the deep groove side.

[0016] This reduces the area where the pressure of the sealed fluid rises in the terminal section.

[0017] Alternatively, the deep groove may be connected to the sealed fluid side.

[0018] This allows the sealed fluid recovered from the deep tank to be returned to the sealed fluid side.

[0019] Alternatively, the shallow groove may extend over the entire circumference of the sliding surface of the sliding member and have a starting end that is connected to the deep groove in the circumferential direction.

[0020] This allows negative pressure to be generated over the entire circumference of the sliding surface of the sliding component.

[0021] Alternatively, the shallow groove and the deep groove can be arranged at equal intervals along the circumference of the sliding surface of the sliding member, and the shallow groove is symmetrical about a radially extending line passing through the deep groove.

[0022] Therefore, it can be used without being restricted by the relative rotation direction of the sliding parts. In addition, since the sealed fluid does not easily flow into the shallow groove near the relative rotation end side compared to the deep groove, negative pressure can also be generated in the shallow groove on the relative rotation end side.

[0023] Furthermore, the shallow groove of the sliding member of the present invention extends circumferentially, meaning that the shallow groove is provided in such a way that it has at least a circumferential component; preferably, it is provided in such a way that the circumferential component is greater than the radial component. Similarly, the deep groove extends radially, meaning that the deep groove is provided in such a way that it has at least a radial component; preferably, it is provided in such a way that the radial component is greater than the circumferential component.

[0024] In addition, the sealed fluid can be a gas or a liquid, or a mist of a mixture of liquid and gas. Attached Figure Description

[0025] Figure 1 This is a longitudinal sectional view showing an example of the mechanical seal of Embodiment 1 of the present invention.

[0026] Figure 2 This is a diagram showing the sliding surface of the stationary sealing ring as viewed from the axial direction.

[0027] Figure 3 It is a sectional view along line AA.

[0028] Figure 4 This is an explanatory diagram showing the vicinity of the liquid induction tank of the negative pressure generating mechanism viewed from the axial direction.

[0029] Figure 5 It is a schematic cross-sectional view cut off near the liquid induction tank using a plane perpendicular to the liquid induction tank.

[0030] Figure 6 FIG. 1 is an explanatory view showing a stationary seal ring of Embodiment 1.

[0031] Figure 7 FIG. 2 is an explanatory view showing a modification 1 of the stationary seal ring of Embodiment 1.

[0032] Figure 8 FIG. 3 is an explanatory view showing a modification 2 of the stationary seal ring of Embodiment 1.

[0033] Figure 9 FIG. 4 is an explanatory view showing a modification 3 of the stationary seal ring of Embodiment 1.

[0034] Figure 10 FIG. 5 is an explanatory view showing a modification 4 of the stationary seal ring of Embodiment 1.

[0035] Figure 11 FIG. 6 is an explanatory view showing a modification 5 of the stationary seal ring of Embodiment 1.

[0036] Figure 12 FIG. 7 is a view showing a sliding surface of the stationary seal ring of Embodiment 2 as viewed from the axial direction. DETAILED DESCRIPTION

[0037] Hereinafter, a mode of the sliding member for embodying the present application will be described based on an embodiment.

[0038] Embodiment 1

[0039] Reference Figures 1 to 5 The sliding member of Embodiment 1 will be described. In this embodiment, a case where the sliding member is a mechanical seal will be described. In addition, the outer diameter side of the sliding member constituting the mechanical seal will be described as the sealed fluid side (high pressure side), and the inner diameter side will be described as the atmospheric side (low pressure side) as a leakage side. In addition, in the drawings, a dot will be sometimes attached to a groove or the like formed on the sliding surface for the purpose of easy description.

[0040] Figure 1 The mechanical seal for general industrial machines shown in FIG. 1 is an inner side type mechanical seal that seals a sealed fluid F that is intended to leak from the outer diameter side toward the inner diameter side of the sliding surface. In this embodiment, a case where the sealed fluid F is a high pressure gas will be described.

[0041] The mechanical seal mainly comprises: a circular rotary sealing ring 20 as a sliding component, which is disposed on the rotating shaft 1 through a sleeve 2 in a state that allows it to rotate together with the rotating shaft 1; and a circular stationary sealing ring 10 as a sliding component, which is disposed on a sealing cover 5 in a non-rotating state and is axially movable. The sealing cover 5 is fixed to the housing 4 of the installed equipment. In this mechanical seal, the stationary sealing ring 10 is subjected to axial force by the bellows 7, and the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotary sealing ring 20 slide in close contact with each other. In addition, the sliding surface 21 of the rotary sealing ring 20 is a flat surface without any recesses.

[0042] The stationary sealing ring 10 and the rotary sealing ring 20 are typically formed from a combination of SiC (hard material) and SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited to these. Any sliding material suitable for use in mechanical seals can be used. Furthermore, SiC can be a material composed of two or more phases with different compositions, such as sintered bodies containing boron, aluminum, carbon, etc., as sintering aids. Examples include SiC with dispersed graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, and SiC-TiN. As for carbon, resin-molded carbon and sintered carbon, such as carbon mixed with carbonaceous and graphitic materials, can be used. In addition to the above-mentioned sliding materials, metallic materials, resin materials, surface-modified materials (coating materials), and composite materials can also be used.

[0043] like Figure 2 As shown, the rotating sealing ring 20 slides relative to the stationary sealing ring 10 as indicated by the arrow. A negative pressure generating mechanism 14 is provided on the sliding surface 11 of the stationary sealing ring 10. The negative pressure generating mechanism 14 has: a fluid induction groove 15 as a deep groove, which communicates with the sealed fluid F side and extends in the inner diameter direction; and a shallow groove 9 for generating negative pressure, which extends concentrically with the stationary sealing ring 10 from the circumferential end of the fluid induction groove 15 on the downstream side of the inner diameter side and is connected to the circumferential end of the fluid induction groove 15 on the upstream side of the inner diameter side. In addition, the portion of the sliding surface 11 other than the negative pressure generating mechanism 14 is a land portion 12 forming a flat end face. In addition, although not shown, a positive pressure generating mechanism, such as a pit, is formed on the land portion 12 located on the outer diameter side of the shallow groove 9.

[0044] Next, based on Figure 2 and Figure 3 A general description of the negative pressure generating mechanism 14 will be given below. Additionally, the following will... Figure 2In this illustration, the end of the shallow groove 9 that connects to the left side of the fluid induction groove 15 is designated as the starting end 9a of the shallow groove 9 (i.e., the upstream side of the sealed fluid F flowing within the shallow groove 9), and the end of the shallow groove 9 that connects to the right side of the fluid induction groove 15 is designated as the ending end 9b of the shallow groove 9 (i.e., the downstream side of the sealed fluid F flowing within the shallow groove 9). Furthermore, for ease of explanation, the depth of the shallow groove 9 is shown as deeper than its actual depth.

[0045] In this embodiment 1, the fluid induction groove 15 extends radially along the stationary sealing ring 10. Furthermore, the fluid induction groove 15 is connected to the beginning end 9a and the end end 9b of the shallow groove 9, i.e., arranged circumferentially. The shallow groove 9 has a bottom surface 9c, an outer surface 9d erected from the outer diameter side of the bottom surface 9c, and an inner surface 9e erected from the inner diameter side of the bottom surface 9c. The outer surface 9d and the inner surface 9e are parallel to each other and perpendicular to the flat surface of the land portion 12.

[0046] In particular, such as Figure 3 As shown, the bottom surface 9k near the starting end 9a of the shallow groove 9 in the bottom surface 9c extends in an arc shape convex toward the opposite side of the sliding surface 11, and the depth of the shallow groove 9 gradually decreases toward the starting end side of the shallow groove 9. That is, the cross-section obtained by cutting near the starting end 9a of the shallow groove 9 using a surface perpendicular to the fluid induction groove portion 15 ( Figure 3 The cross section shown (i.e., the circumferential cross section) is bent in a way that it is recessed toward the fluid induction groove 15.

[0047] A wall portion 9f is formed at the initial end 9a of the shallow channel 9, dividing the shallow channel 9 and the fluid induction channel 15. Furthermore, the top 9g of the wall portion 9f is a radially extending line, disposed on the flat end face of the land portion 12. Figure 3 The shallow groove 9 is located slightly deeper on the upper surface, near the bottom surface 9c. In the space G1 on the flat end face side of the land portion 12 of the top 9g, the shallow groove 9 communicates with the fluid induction groove portion 15. Thus, the flow path cross-sectional area of ​​the initial end portion 9a of the shallow groove 9 gradually decreases towards the fluid induction groove portion 15.

[0048] Furthermore, the bottom surface 9m near the end portion 9b of the shallow groove 9 in the bottom surface 9c extends in an arc shape convex toward the opposite side of the sliding surface 11, and the depth of the shallow groove 9 gradually becomes shallower toward the end side of the shallow groove 9. That is, the cross-section obtained by cutting near the end portion 9b of the shallow groove 9 with a surface perpendicular to the fluid induction groove portion 15 is bent in a way that is concave toward the fluid induction groove portion 15.

[0049] A wall portion 9h that divides the shallow groove 9 and the fluid inducing groove portion 15 is formed at the terminal end portion 9b of the shallow groove 9. In addition, a top portion 9j of the wall portion 9h is disposed at a position deeper than the flat end surface of the land portion 12, that is, at a position on the side of the bottom surface 9c. In a space G2 on the flat end surface side of the land portion 12 of the top portion 9j, the shallow groove 9 communicates with the fluid inducing groove portion 15. In this way, the flow path cross-sectional area of the terminal end portion 9b of the shallow groove 9 gradually decreases toward the fluid inducing groove portion 15.

[0050] In addition, a bottom surface 9n between a bottom surface 9k in the vicinity of the start end portion 9a in the bottom surface 9c and a bottom surface 9m in the vicinity of the terminal end portion 9b is a flat surface parallel to the flat end surface of the land portion 12, and is the deepest portion in the shallow groove 9.

[0051] In addition, the vicinity of the start end portion 9a of the shallow groove 9 and the vicinity of the terminal end portion 9b of the shallow groove 9 are symmetrical with respect to a line LN (refer to FIG. 6) that extends in the radial direction along the fluid inducing groove portion 15. Figure 2

[0052] In addition, the depth dimension L10 of the fluid inducing groove portion 15 is deeper than the depth dimension L20 of the shallow groove 9, that is, the depth dimension between the flat end surface of the land portion 12 and the bottom surface 9n of the shallow groove 9 (L10 > L20).

[0053] Specifically, the depth dimension L10 of the fluid inducing groove portion 15 is formed to be 100 μm, and the depth dimension L20 of the shallow groove 9 is formed to be 1 μm. In addition, as long as the depth dimension of the fluid inducing groove portion 15 is formed to be deeper than the depth dimension of the shallow groove 9, the depth dimensions of the fluid inducing groove portion 15 and the shallow groove 9 can be freely changed, and it is preferable that the dimension L10 be more than five times the dimension L20.

[0054] Next, the operation at the time of relative rotation of the stationary seal ring 10 and the rotating seal ring 20 will be described. Figure 4 Figure 5 First, at the time of non-operation of the general industrial machine in which the rotating seal ring 20 does not rotate, the sealed fluid F flows into the shallow groove 9 via the fluid inducing groove portion 15. In addition, since the stationary seal ring 10 is pressed by the bellows 7 toward the rotating seal ring 20, the amount of leakage to the low pressure side from between the sliding surfaces 11, 21 is almost zero.

[0055] When the rotating seal ring 20 relatively rotates with respect to the stationary seal ring 10, the sealed fluid F on the outer diameter side of the sliding surfaces 11, 21 is introduced between the sliding surfaces 11, 21, and the sliding surfaces 11, 21 slightly separate due to the positive pressure generated by the above-described positive pressure generation mechanism. In addition, as Figure 4 Figure 5 ​​​As shown, the sealed fluid F flowing into the shallow groove 9 moves in the direction of rotation of the rotary seal ring 20 due to friction between the sealed fluid F and the sliding surface 21, as indicated by arrow LI.

[0056] Since the cross-sectional area of the flow path of the terminal portion 9b of the shallow groove 9 gradually decreases toward the fluid inducing groove portion 15, the fluid collects, and thus the pressure in the vicinity of the terminal portion 9b becomes the highest, and the sealed fluid F whose pressure has increased flows into the fluid inducing groove portion 15 through the space surrounded by the outer side surface 9d, the inner side surface 9e, the top portion 9j, and the sliding surface 21 of the rotary seal ring 20, as indicated by arrow L2, but since the fluid inducing groove portion 15 has a space to the extent that the fluid can be dispersed, the collected fluid is dispersed, and by the dispersion of the fluid, the increased pressure is reduced, and the sealed fluid F of high pressure does not flow into the shallow groove 9 on the upstream side, that is, the initial portion 9a side. On the other hand, at the initial portion 9a of the shallow groove 9, the volume of the shallow groove 9 on the downstream side of the top portion 9g sharply increases, and thus the fluid is dispersed, and thus a negative pressure is generated, which extends over the entire area of the shallow groove 9.

[0057] In addition, when the relative rotational speed of the stationary seal ring 10 and the rotary seal ring 20 becomes a certain value or more, the sealed fluid F in the fluid inducing groove portion 15 is pushed out to the outer diameter side by the sealed fluid F flowing from the terminal portion 9b of the shallow groove 9, as indicated by arrow L3. In addition, when the stationary seal ring 10 and the rotary seal ring 20 relatively rotate, the sealed fluid F flows at all times from the outer diameter side of the sliding surfaces 11, 21 and the fluid inducing groove portion 15 into between the sliding surfaces 11, 21, and the lubricity is excellent.

[0058] At this time, the sealed fluid F on the periphery of the portion other than the terminal portion 9b of the shallow groove 9 is sucked into the shallow groove 9, as indicated by arrow HI, due to the negative pressure generated in the shallow groove 9. On the other hand, as described above, the sealed fluid F in the vicinity of the terminal portion 9b of the shallow groove 9 is of high pressure, and thus the sealed fluid F in the vicinity of the terminal portion 9b of the shallow groove 9 remains in the state of being located on the land portion 12, as indicated by arrow H2, and hardly enters the shallow groove 9. In addition, the sealed fluid F in the vicinity of the fluid inducing groove portion 15 enters the fluid inducing groove portion 15, as indicated by arrow H3, and a portion of the sealed fluid F in the fluid inducing groove portion 15 flows out to between the sliding surfaces 11, 21, as indicated by arrow H4, due to friction or the like between the sealed fluid F and the sliding surface 21.

[0059] As described above, since the cross-sectional area of the flow path of the terminal portion 9b of the shallow groove 9 gradually decreases toward the fluid inducing groove portion 15, when the stationary seal ring 10 and the rotary seal ring 20 relatively rotate, the pressure of the sealed fluid F in the shallow groove 9 is not easily increased, and the shallow groove 9 is easily maintained at a negative pressure, and it is possible to recover the sealed fluid F which is intended to leak to the atmospheric side.

[0060] Further, since the fluid inducing groove portion 15 deeper than the shallow groove 9 is provided on the downstream side of the relative rotation of the terminal portion 9b of the shallow groove 9, the pressure-increased sealed fluid F flowing in the vicinity of the terminal portion 9b flows into the fluid inducing groove portion 15, the pressure-increased sealed fluid F is dispersed in the fluid inducing groove portion 15, and the pressure-increased sealed fluid F is inhibited from flowing out between the sliding surfaces 11, 21, so that the positive pressure between the sliding surfaces 11, 21 can be inhibited. Thus, the negative pressure generation ability of the shallow groove 9 can be prevented from being decreased. Further, since the pressure-increased sealed fluid F is dispersed in the fluid inducing groove portion 15, the pressure-increased sealed fluid F does not flow into the shallow groove 9 on the downstream side, and the negative pressure can be appropriately generated in the shallow groove 9 on the downstream side.

[0061] Further, since the terminal portion 9b of the shallow groove 9 communicates with the fluid inducing groove portion 15, the pressure-increased sealed fluid F is inhibited from flowing out between the sliding surfaces 11, 21, and the positive pressure between the sliding surfaces 11, 21 can be inhibited.

[0062] Further, the bottom surface 9c in the vicinity of the terminal portion 9b of the shallow groove 9 is gradually shallowed toward the fluid inducing groove portion 15. Thus, the sealed fluid F is gathered in a manner that the sealed fluid F flows from the terminal portion 9b of the shallow groove 9 toward the fluid inducing groove portion 15 and from the bottom surface 9n of the shallow groove 9 toward the sliding surface, so that the sealed fluid F is easily affected by the tendency of the sliding surface, and the sealed fluid F can flow into the fluid inducing groove portion 15 on the downstream side in a large amount.

[0063] Further, since the bottom surface 9c of the terminal portion 9b of the shallow groove 9 is curved in a manner that the bottom surface 9c is recessed toward the fluid inducing groove portion 15, and the top 9j of the terminal portion 9b as the end portion is directed toward the sliding surface 21 on the opposite side, that is, toward the axial direction of the stationary seal ring 10, the region in which the pressure of the sealed fluid F is increased in the terminal portion 9b can be made small in the circumferential direction. That is, the negative pressure generation region of the shallow groove 9 can be ensured to be large. Further, the pressure of the sealed fluid F in the shallow groove 9 can be maintained to be not increased until the upstream side of the fluid inducing groove portion 15, and the region in which the pressure is increased is easily arranged in the vicinity of the boundary between the terminal portion 9b and the fluid inducing groove portion 15, so that the pressure-increased sealed fluid F is not easily returned to the shallow groove 9, and the shallow groove 9 is easily maintained to be under the negative pressure.

[0064] Further, since the bottom surface 9c of the terminal portion 9b of the shallow groove 9 is curved in a manner that the bottom surface 9c is recessed toward the fluid inducing groove portion 15, the flow of the sealed fluid F in the shallow groove 9 is not easily disturbed, and the flow of the sealed fluid F becomes smooth.

[0065] Further, since the fluid-inducing groove 15 communicates with the outer-diameter-side sealed-fluid side, the sealed fluid F recovered from the shallow groove 9 can be returned to the outer-diameter-side sealed-fluid F side. Further, at the time of relative rotation of the stationary seal ring 10 and the rotating seal ring 20, the sealed fluid F is easily returned to the outer-diameter-side sealed-fluid F side by centrifugal force, and leakage of the sealed fluid F to a position on the low-pressure side on the inner-diameter side of the sliding surfaces 11, 21, which is closer than the sliding surfaces 11, 21, can be reduced.

[0066] Further, since the shallow groove 9 extends on concentric circles over the entire circumferential range of the sliding surface 11, and the start end portion 9a and the end end portion 9b communicate with one fluid-inducing groove 15 in the circumferential direction, negative pressure of the shallow groove 9 can be generated over the entire circumferential range of the sliding surface 11.

[0067] Further, the start end portion 9a of the shallow groove 9 communicates with the fluid-inducing groove 15 via the space Gl, and at the time of relative rotation of the stationary seal ring 10 and the rotating seal ring 20, the sealed fluid F is not easily introduced from the fluid-inducing groove 15 to the start end portion 9a side of the shallow groove 9, and thus a large negative pressure can be generated in the shallow groove 9.

[0068] Further, since the start end portion 9a and the end end portion 9b of the shallow groove 9 are symmetrically shaped with reference to a line LN extending in the radial direction along the fluid-inducing groove 15, the start end portion 9a and the end end portion 9b can be used regardless of the direction of relative rotation of the stationary seal ring 10 and the rotating seal ring 20.

[0069] Further, in the above-described embodiment 1, a mode in which the fluid-inducing groove 15 as the deep groove communicates with the outer-diameter-side sealed-fluid F side is exemplified, but is not limited thereto, and for example, as in the stationary seal ring 100 of modification example 1 shown in Figure 6 the fluid-inducing groove 151 as the deep groove does not communicate with the atmosphere A side and the sealed-fluid F side of the stationary seal ring 10.

[0070] Further, in a case where the amount of the sealed fluid F flowing out from the end end portion 9b of the shallow groove 9 is small, that is, in a case where it is within the allowable leakage amount to the leakage side, for example, as in the stationary seal ring 101 of modification example 2 shown in Figure 7 the fluid-inducing groove 152 as the deep groove communicates with the atmosphere A side on the inner-diameter side of the stationary seal ring 101.

[0071] That is, the deep groove can be freely changed in size and shape as long as it can recover the sealed fluid F flowing out from the end end portion 9b of the shallow groove 9 to the extent that positive pressure is not generated or can be suppressed between the sliding surfaces 11, 21.

[0072] Further, in the above-described embodiment 1, a mode in which the bottom surface 9c of the start end portion 9a and the end end portion 9b of the shallow groove 9 is curved in a manner of being recessed toward the fluid-inducing groove 15 side is exemplified, but is not limited thereto, and for example, as in the stationary seal ring 100 of modification example 1 shown inFigure 8 As with the stationary seal ring 102 of Modification Example 3 shown, the bottom surface 90c of the start end portion 90a of the shallow groove 90 extends in a linear manner inclined toward the end surface 90g of the wall portion 90f, and the bottom surface 90c' of the end portion 90b extends in a linear manner inclined toward the end surface 90j of the wall portion 90h. Thereby, the flow of the sealed fluid F flowing from the inside of the shallow groove 90 toward the fluid inducing groove portion 15 can be made smooth.

[0073] Further, for example, it is also possible to provide the shallow groove 9 with a land portion 121 between the start end portion 9a and the end portion 9b thereof and the fluid inducing groove portion 15. Figure 9 As with the stationary seal ring 103 of Modification Example 4 shown, the bottom surface 91c of the start end portion 91a of the shallow groove 91 and the bottom surface 91c' of the end portion 91b are curved in a manner bulging toward the opposite side of the circumferential direction of the fluid inducing groove portion 15.

[0074] That is, as long as the start end portion and the end portion of the shallow groove gradually become shallower toward the deep groove, the cross-sectional shape thereof can be freely changed. Further, in the case where the relative rotation direction of the sliding member is only one direction, as long as at least the end portion of the shallow groove gradually becomes shallower toward the deep groove.

[0075] Further, in the present embodiment, the case where the end portion 9b of the shallow groove 9 gradually becomes shallower toward the fluid inducing groove portion 15 and the radial width of the shallow groove 9 is constant over the entire circumferential direction is exemplified, although this form is more preferable, but is not limited thereto, and for example, it is also possible that the radial width of the end portion of the shallow groove gradually becomes narrower. That is, as long as the end portion of the shallow groove is formed so that the flow path cross-sectional area becomes narrower toward the deep groove.

[0076] Further, in the above-described Embodiment 1, the case where the start end portion 9a and the end portion 9b of the shallow groove 9 communicate with the fluid inducing groove portion 15 is exemplified, but it is also possible to provide the stationary seal ring 105 of Modification Example 5 shown with a land portion 121 between the start end portion 10a and the end portion 10b of the shallow groove 10 and the fluid inducing groove portion 15. Figure 10 That is, as long as the fluid inducing groove portion 15 is arranged adjacent to the downstream side of the end portion 9b.

[0077] Further, in the above-described Embodiment 1, the case where the top portion 9g of the wall portion 9f and the top portion 9j of the wall portion 9h of the shallow groove 9 are arranged at positions slightly closer to the bottom surface 9c side than the flat end surface of the land portion 12 is exemplified, but is not limited thereto, and it is also possible to provide the stationary seal ring 106 of Modification Example 6 shown with the top portion 9g' of the shallow groove 9 and the top portion 9j' arranged in the same planar manner as the flat end surface of the land portion 12. Figure 11 That is, as long as the stationary seal ring 106 can prevent the generation of positive pressure above the allowable value between the sliding surfaces of the sliding member, the start end portion and the end portion of the shallow groove can not communicate with the deep groove.

[0078] Embodiment 2

[0079] Next, with reference to Figure 12The sliding component of Embodiment 2 will be described. Furthermore, repeated structural descriptions of components with the same structure as those in the above embodiments will be omitted.

[0080] like Figure 12 As shown, on the sliding surface 115 of the stationary sealing ring 105 in Embodiment 2, a plurality of negative pressure generating mechanisms 145 (three in this embodiment) are formed circumferentially. The negative pressure generating mechanism 145 has: a fluid induction groove 153 extending from the outer diameter side to the inner diameter side; a first shallow groove 95 that is arc-shaped when viewed axially and extends from the inner diameter side end of the fluid induction groove 153 to the relative rotation end side, i.e., extending counterclockwise along the paper surface; and a second shallow groove 96 that is arc-shaped when viewed axially and extends from the inner diameter side end of the fluid induction groove 153 to the relative rotation start side, i.e., extending clockwise along the paper surface.

[0081] The initial end portion 95a of the first shallow groove 95 is shallower than the middle portion 95c and the terminal portion 95b of the first shallow groove 95. The middle portion 95c and the terminal portion 95b extend parallel to the flat end face of the land portion 122 and are formed to the same depth. Similarly, the terminal portion 96b of the second shallow groove 96 is shallower than the initial end portion 96a and the middle portion 96c of the second shallow groove 96. The initial end portion 96a and the middle portion 96c extend parallel to the flat end face of the land portion 122 and are formed to the same depth. In other words, the initial end portion 95a of the first shallow groove 95 and the terminal portion 96b of the second shallow groove 96 are formed to gradually become shallower towards the fluid induction groove portion 153.

[0082] Furthermore, the first shallow groove 95 and the second shallow groove 96 are symmetrical in shape with reference to the line LN extending radially along the fluid induction groove 153, so they can be used regardless of the relative rotation direction of the stationary sealing ring 105 and the rotating sealing ring 20.

[0083] When the rotating sealing ring 20 rotates relative to the stationary sealing ring 105, since the fluid induction groove 153 is located downstream of the second shallow groove 96, the sealed fluid F in the second shallow groove 96 moves from the beginning end 96a to the middle part 96c and the end part 96b. Even if the pressure in the end part 96b increases, it is easy to flow into the fluid induction groove 153. In addition, since the opening between the beginning end 95a of the first shallow groove 95 and the fluid induction groove 153 is small, the sealed fluid F does not easily flow from the fluid induction groove 153 into the first shallow groove 95, and negative pressure can be generated even in the first shallow groove 95.

[0084] Furthermore, since the sealed fluid F flowing out from the terminal portion 95b of the first shallow groove 95 to the sliding surface 115 can be drawn in from the beginning end 96a of the second shallow groove 96 of the negative pressure generating mechanism 145 adjacent to the downstream side, leakage of the sealed fluid F to the atmosphere A side can be suppressed.

[0085] In addition, the terminal portion 95b of the first shallow groove 95 and the start portion 96a of the second shallow groove 96, which are adjacent in the circumferential direction, can also be continuous in the circumferential direction.

[0086] In addition, the shapes of the above-described modified examples 1 to 6 can also be applied to the sliding member of the present embodiment 2.

[0087] The above-described embodiments of the present application have been described based on the drawings, but the specific structure is not limited to these embodiments, and modifications or additions within the scope of the gist of the present application are also included in the present application.

[0088] For example, in the above-described embodiments, a mechanical seal for general industrial machinery has been described as an example of the sliding member, but other mechanical seals for automobiles or water pumps, etc. can also be used. In addition, the sliding member is not limited to a mechanical seal, but can also be a sliding bearing or the like.

[0089] In addition, in the above-described embodiments, an example in which the negative pressure generating mechanism is provided only in the stationary seal ring has been described, but the negative pressure generating mechanism can also be provided only in the rotating seal ring, or can be provided in both the stationary seal ring and the rotating seal ring.

[0090] In addition, in the above-described embodiments, an example in which the sealed fluid side is the high pressure side and the leakage side is the low pressure side has been described, but the sealed fluid side can also be the low pressure side and the leakage side can be the high pressure side, or the sealed fluid side and the leakage side can be approximately the same pressure.

[0091] In addition, in the above-described embodiments, an example of an inner side type mechanical seal that seals a sealed fluid F that is intended to leak from the outer diameter side of the sliding surface toward the inner diameter side has been described, but this is not limiting, and an outer side type mechanical seal that seals a sealed fluid F that is intended to leak from the inner diameter side of the sliding surface toward the outer diameter side can also be used.

[0092] Explanation of Reference Numerals

[0093] 9: shallow groove; 9a: start portion; 9b: terminal portion; 9c: bottom surface; 10: stationary seal ring (sliding member); 11: sliding surface; 14: negative pressure generating mechanism; 15: liquid inducing groove portion (deep groove); 20: rotating seal ring (sliding member); 21: sliding surface; 90: shallow groove; 90a: start portion; 90b: terminal portion; 91: shallow groove; 91a: start portion; 91b: terminal portion; 92: shallow groove; 92a: start portion; 92b: terminal portion; 95: first shallow groove (shallow groove); 95a: start portion; 95b: terminal portion; 96: second shallow groove (shallow groove); 96a: start portion; 96b: terminal portion; 100 to 105: stationary seal ring; 145: negative pressure generating mechanism; 151, 152, 153: liquid inducing groove portion (deep groove); A: atmosphere; F: sealed fluid.

Claims

1. A sliding member which is annular, is arranged at a portion to be relatively rotated in a rotary machine, and slides against another sliding member, wherein a shallow groove for negative pressure generation extending in a circumferential direction, a deep groove deeper than the shallow groove for recovering a sealed fluid in the shallow groove, and a land portion constituting a flat end surface to slide against a sliding surface of the other sliding member are provided on a sliding surface of the sliding member, the shallow groove has a terminal end portion in which a flow passage cross-sectional area narrows toward the deep groove, the terminal end portion of the shallow groove gradually becomes shallower toward the deep groove, a wall portion dividing the shallow groove and the deep groove is formed at the terminal end portion of the shallow groove, and a top portion of the wall portion is disposed at a position deeper than the flat end surface.

2. The sliding member according to claim 1, wherein a bottom surface of the terminal end portion of the shallow groove is curved in a manner of being recessed toward the deep groove side.

3. The sliding member according to claim 1 or 2, wherein the deep groove is in communication with a sealed fluid side.

4. The sliding member according to claim 1 or 2, wherein the shallow groove extends over an entire circumferential range of the sliding surface of the sliding member, and has a start end portion connected to the deep groove in the circumferential direction.

5. The sliding member according to claim 1 or 2, wherein the shallow grooves and the deep groove are arranged at equal intervals in the circumferential direction of the sliding surface of the sliding member, and the shallow grooves are in a symmetrical shape with respect to a line extending in a radial direction through the deep groove.

6. A sliding member which is annular, is arranged at a portion to be relatively rotated in a rotary machine in use, and slides against another sliding member in use, wherein a shallow groove for negative pressure generation extending in a circumferential direction and generating a negative pressure in use, and a deep groove deeper than the shallow groove for recovering a sealed fluid in the shallow groove in use are provided on a sliding surface of the sliding member, the shallow groove has a start end portion and a terminal end portion in which a flow passage cross-sectional area narrows toward the deep groove, the shallow groove extends over a circumferential range of the sliding surface of the sliding member, the start end portion and the terminal end portion of the shallow groove are arranged adjacent to both sides of the deep groove, and a land portion is formed between the start end portion of the shallow groove and the deep groove closest to the shallow groove.

7. The sliding member according to claim 6, wherein the terminal end portion of the shallow groove gradually becomes shallower toward the deep groove.

8. The sliding member according to claim 7, wherein a bottom surface of the terminal end portion of the shallow groove is curved in a manner of being recessed toward the deep groove side.

9. The sliding member according to claim 6 or 7, wherein the deep groove is in communication with a sealed fluid side.

10. The sliding member according to claim 6 or 7, wherein the shallow groove extends over an entire circumferential range of the sliding surface of the sliding member, and a top portion of the shallow groove and a flat surface of the land portion are arranged in a same planar shape. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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