Pair of sliding components

Abstract

Provided is a pair of sliding components capable of suppressing wear between sliding surfaces from low relative rotational speeds to high relative rotational speeds, and suppressing leakage of a hermetically-sealed fluid. First positive-pressure generation grooves 14 and 15 are provided respectively with end portions 14B and 15B, which are positioned further to a hermetically-sealed fluid space S2 side than an end portion 24B of a second positive-pressure generation groove 24 is. The radial length α of the second positive-pressure generation groove 24 is 5-70% of the radial length β of the first positive-pressure generation groove 14.

Description

A pair of sliding parts

[0001] The present invention relates to sliding parts that rotate relative to one another, and relates to, for example, a pair of sliding parts used in a shaft sealing device that seals the rotating shaft of a rotating machine in an automobile, general industrial machine, or other sealing field, or a pair of sliding parts used in a bearing of a machine in an automobile, general industrial machine, or other bearing field.

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

[0003] For example, a mechanical seal disclosed in Patent Document 1 includes a pair of annular sliding elements configured to rotate relative to one another, with a sealed fluid present in an outer space and a low-pressure fluid present in an inner space. One of the sliding elements has a plurality of spiral grooves that communicate with the inner space, extend in an arc shape while inclining circumferentially from the inner diameter end toward the outer diameter side, and have closed ends downstream in the direction of relative rotation. During relative rotation of the pair of sliding elements, low-pressure fluid is introduced from the inner space into the spiral grooves of one of the sliding elements, generating positive pressure at and near the ends, slightly separating the sliding surfaces of the pair of sliding elements and thereby achieving low friction.

[0004] Japanese Patent Application Laid-Open No. 62-31775 (pages 2 and 3, Figure 2)

[0005] However, in the sliding parts such as those in Patent Document 1, the spiral groove is provided on one of the sliding parts, extends from the inner diameter end to the outer diameter side, and introduces low-pressure fluid from the internal space. This allows for low wear, but sufficient dynamic pressure is not generated in the spiral groove until the sliding parts reach a relative rotational speed equal to or greater than a certain level, and it takes time to separate the sliding surfaces, which could result in wear between the sliding surfaces.

[0006] The present invention has been made in light of these problems, and aims to provide a pair of sliding components that can suppress wear between the sliding surfaces and can suppress leakage of the sealed fluid from low relative rotation speeds to high relative rotation speeds.

[0007] In order to solve the above problem, a pair of sliding components of the present invention is a pair of sliding components that are arranged at relative rotational positions of a rotary machine and whose sliding surfaces slide relative to each other, wherein the sliding surface of a first sliding component is provided with a first positive pressure generating groove that communicates with a space on the leakage side, extends in the direction of relative rotation of a second sliding component, and has a closed terminal end portion; the sliding surface of the second sliding component is provided with a second positive pressure generating groove that communicates with the space on the leakage side, extends in the direction of relative rotation of the first sliding component, and has a closed terminal end portion; the sliding surfaces of the first sliding component and the second sliding component slide crosswise such that at least a portion of the first positive pressure generating groove and the second positive pressure generating groove overlap; the first positive pressure generating groove has a terminal end that is located closer to the sealed fluid space than the terminal end of the second positive pressure generating groove; and the radial length of the second positive pressure generating groove is 5% or more and 70% or less of the radial length of the first positive pressure generating groove. According to this, the portion where the first positive pressure generating groove and the second positive pressure generating groove intersect is connected, so that during relative rotation, in addition to the connecting portion to the leakage side space of the first positive pressure generating groove and the second positive pressure generating groove, fluid can be taken into the sliding surface from the opposing first positive pressure generating groove or second positive pressure generating groove, and a force to separate the sliding surfaces can be instantly generated.In addition, the difference in radial length between the first positive pressure generating groove and the second positive pressure generating groove can be ensured to be at least 30% of the length of the first positive pressure generating groove, and the positive pressure of the first positive pressure generating groove and the positive pressure of the second positive pressure generating groove are prevented from interfering with each other, so the sliding surfaces can be smoothly separated from each other from low relative rotation speeds to high relative rotation speeds.

[0008] The radial length of the second positive pressure generating groove may be 10% to 35% of the radial length of the first positive pressure generating groove, which ensures a larger difference in radial length between the first and second positive pressure generating grooves, thereby reliably preventing the positive pressures of the first and second positive pressure generating grooves from interfering with each other.

[0009] The radial length of the land of the first positive pressure generating groove on the sliding surface of the first sliding component facing the sealed fluid space may be no more than twice the radial length of the second positive pressure generating groove. This ensures a large proportion of the radial length of the first positive pressure generating groove on the sliding surface of the first sliding component, thereby ensuring the dynamic pressure generating effect of the first positive pressure generating groove at high relative rotational speeds.

[0010] The first sliding component may be a rotary seal ring fixed to the rotating shaft, and the second sliding component may be a stationary seal ring fixed to the housing. In this configuration, since the first sliding component is a rotary seal ring having a first positive pressure generating groove with a relatively long radial length, positive pressure can be reliably generated in the first positive pressure generating groove at high relative rotation speeds.

[0011] The first positive pressure generating groove and the second positive pressure generating groove may be spiral grooves extending from the leakage-side space toward the sealed fluid-side space at an angle from the upstream side of the relative rotation to the downstream side of the relative rotation, which allows a large number of first positive pressure generating grooves and second positive pressure generating grooves to be arranged in the circumferential direction, thereby increasing the degree of freedom in design.

[0012]

[0023] FIG. 1 is a longitudinal cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention.

[0024] FIG. 2 is a view of the sliding surface of a rotary seal ring as viewed from the axial direction.

[0025] FIG. 3 is a view of the sliding surface of a stationary seal ring as viewed from the axial direction.

[0026] FIG. 4 is a schematic diagram illustrating the state in which the sliding surface of the stationary seal ring and the sliding surface of the rotary seal ring are arranged opposite each other. Note that the second positive pressure generating groove of the stationary seal ring is indicated by a two-dot dashed line.

[0027] (a) is a cross-sectional view schematically illustrating another groove of the first positive pressure generating groove and a second positive pressure generating groove, and (b) is a cross-sectional view schematically illustrating one groove of the first positive pressure generating groove and a second positive pressure generating groove.

[0028] (a) is an explanatory view of the movement of fluid in one groove of the first positive pressure generating groove and another groove as viewed from the axial direction, and (b) is an explanatory view of the movement of fluid in the second positive pressure generating groove as viewed from the axial direction.

[0029] (a) to (c) are cross-sectional views schematically illustrating the state of a pair of sliding components at each relative rotational speed.

[0029] (a) to (c) are explanatory views illustrating the change in position of the intersection of the first positive pressure generating groove and the second positive pressure generating groove. 1A is a longitudinal cross-sectional view illustrating a state in which the sliding surfaces are relatively misaligned in the radial direction at high relative rotational speeds, and FIG. 1B is an axial cross-sectional view of the same. FIG. 1B is a cross-sectional view schematically illustrating another first positive pressure generating groove and a second positive pressure generating groove in a second embodiment of the present invention. FIG. 1C is a view of the sliding surface of a rotary seal ring in a third embodiment of the present invention, viewed from the axial direction. FIG. 1D is a view of the sliding surface of a rotary seal ring in a fourth embodiment of the present invention, viewed from the axial direction. FIG. 1E is a view of the sliding surface of a rotary seal ring in a fifth embodiment of the present invention, viewed from the axial direction. FIG. 1F is a view of the sliding surface of a stationary seal ring of a first modified example, viewed from the axial direction. FIG. 1G is a schematic view illustrating a state in which the sliding surface of a stationary seal ring and the sliding surface of a rotary seal ring of a second modified example are arranged opposite each other. FIG. 1G is a view of the sliding surface of a rotary seal ring of a third modified example, viewed from the axial direction. FIG. 1H is a view of the sliding surface of a stationary seal ring of a third modified example, viewed from the axial direction. FIG. 1H is a view of the sliding surface of a rotary seal ring of a fourth modified example, viewed from the axial direction.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pair of sliding elements according to the present invention will be described below with reference to the following examples.

[0014] A pair of sliding elements according to a first embodiment will be described with reference to Figs. 1 to 9. In this embodiment, the sliding elements will be described as mechanical seals. A sealed fluid is present in the outer space of the mechanical seal, and atmospheric air is present in the inner space. The outer diameter side of the sliding elements 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, grooves and the like formed on the sliding surfaces may be indicated by dots in the drawings.

[0015] 1 is an inside type mechanical seal for general industrial machinery that seals a sealed fluid F that attempts to leak from the outer diameter side toward the inner diameter side of the sliding surface, and has an inner space S1 as the leakage side space that communicates with the atmosphere A. In this embodiment, the sealed fluid F is a high-pressure liquid, and the atmosphere A is a gas with a lower pressure than the sealed fluid F.

[0016] The mechanical seal is mainly composed of an annular rotary seal ring 10 as a first sliding component, and an annular stationary seal ring 20 as a second sliding component. The rotary seal ring 10 is attached to the rotary shaft 1 via a bellows 7 fixed thereto so as to be rotatable together with the rotary shaft 1. The stationary seal ring 20 is fixed in a non-rotating state via a gasket 5 to the housing 4 of the device to which it is attached.

[0017] The rotary seal ring 10 is biased in the axial direction by a spring 2. This allows the sliding surface 21 of the stationary seal ring 20 and the sliding surface 11 of the rotary seal ring 10 to slide closely against each other.

[0018] The inner diameter of the stationary seal ring 20 is the same as the inner diameter of the rotary seal ring 10. The outer diameter of the stationary seal ring 20 is larger than the outer diameter of the rotary seal ring 10. In other words, the sliding surface 21 of the stationary seal ring 20 is made up of a sliding portion 21a that substantially slides relative to the sliding surface 11 of the rotary seal ring 10, and a protruding portion 21b that protrudes outward from the sliding portion 21a.

[0019] The stationary seal ring 20 and the rotating seal ring 10 are typically formed of SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited to this. Any sliding material used as a sliding material for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, or other sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC consisting of SiC and Si, SiC-TiC, and SiC-TiN. Examples of carbon include a mixture of carbonaceous and graphitic materials, resin-molded carbon, and sintered carbon. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), composite materials, and the like can also be used.

[0020] 2, a plurality of first positive pressure generating grooves 15 and a plurality of first positive pressure generating grooves 14 are provided on the sliding surface 11 of the rotary seal ring 10. The first positive pressure generating grooves 14 and the first positive pressure generating grooves 15 have different lengths. The rotary seal ring 10 rotates clockwise as shown by the arrow when viewed axially from the sliding surface 21.

[0021] The first positive pressure generating groove 14 has an inner diameter side end, i.e., a relative rotation starting end 14A, which communicates with the inner space S1, and extends in an arc shape from the starting end 14A toward the outer diameter side, inclining upstream in the rotation direction of the rotary seal ring 10. The outer diameter side end of the first positive pressure generating groove 14, i.e., a relative rotation terminal end 14B, is closed so as not to communicate with the outer space S2, which is the sealed fluid space. This first positive pressure generating groove 14 has an arc shape that is convex toward the outer diameter side.

[0022] More specifically, the first positive pressure generating groove 14 is composed of a bottom surface 14a, a wall portion 14b, and side wall portions 14c and 14d. The bottom surface 14a is flat from a starting end 14A to a terminal end 14B and extends parallel to the flat surface of the land 12. The wall portion 14b extends perpendicularly from the edge of the terminal end 14B of the bottom surface 14a toward the flat surface of the land 12. The side wall portions 14c and 14d extend perpendicularly from both side edges of the bottom surface 14a toward the flat surface of the land 12.

[0023] The angle formed between the wall portion 14b and the side wall portion 14c is an obtuse angle, and the angle formed between the wall portion 14b and the side wall portion 14d is an acute angle. The acute angle portion 14f of the wall portion 14b on the side wall portion 14d side is located upstream in the rotation direction of the rotary seal ring 10 from the obtuse angle portion 14e of the wall portion 14b on the side wall portion 14c side. In this embodiment, the acute angle portion 14f is approximately 30 degrees, and the obtuse angle portion 14e is approximately 140 degrees. From the perspective of positive pressure generation capability, the acute angle portion 14f is preferably 20 to 35 degrees.

[0024] The first positive pressure generating groove 15 has an inner diameter side end, i.e., a relative rotation starting end 15A, that communicates with the inner space S1 and extends in an arc shape from the starting end 15A toward the outer diameter side, inclined upstream in the direction of rotation of the rotary seal ring 10. The outer diameter side end of the first positive pressure generating groove 15, i.e., a relative rotation terminal end 15B, is closed so as not to communicate with the outer space S2. This first positive pressure generating groove 15 has an arc shape that is convex toward the outer diameter side. Furthermore, as will be described in detail later, this first positive pressure generating groove 15 has a longer extension distance than the first positive pressure generating groove 14. Note that the extension distance refers to the distance from the starting end 14A, 15A to the terminal end 14B, 15B of the first positive pressure generating grooves 14, 15.

[0025] More specifically, the first positive pressure generating groove 15 is composed of a bottom surface 15a, a wall portion 15b, and side wall portions 15c and 15d. The bottom surface 15a is flat from a starting end 15A to a terminal end 15B and extends parallel to the flat surface of the land 12. The wall portion 15b extends perpendicularly from the edge of the terminal end 15B of the bottom surface 15a toward the flat surface of the land 12. The side wall portions 15c and 15d extend perpendicularly from both side edges of the bottom surface 15a toward the flat surface of the land 12.

[0026] The angle formed between the wall portion 15b and the side wall portion 15c is an obtuse angle, and the angle formed between the wall portion 15b and the side wall portion 15d is an acute angle. The acute angle portion 15f of the wall portion 15b on the side wall portion 15d side is located upstream in the rotation direction of the rotary seal ring 10 from the obtuse angle portion 15e of the wall portion 15b on the side wall portion 15c side. In this embodiment, the acute angle portion 15f is approximately 30 degrees, and the obtuse angle portion 15e is approximately 140 degrees. From the perspective of positive pressure generation capability, the acute angle portion 15f is preferably 20 to 35 degrees.

[0027] The first positive pressure generating grooves 15 are equally spaced in the circumferential direction of the sliding surface 11. Furthermore, a plurality of (three in Example 1) first positive pressure generating grooves 14 are equally spaced between adjacent first positive pressure generating grooves 15 in the circumferential direction. The first positive pressure generating grooves 14 and the first positive pressure generating grooves 15 extend parallel to each other.

[0028] The first positive pressure generating grooves 14 and the first positive pressure generating groove 15 are arranged so that multiple grooves overlap each other in the radial direction when viewed from the axial direction. In other words, two first positive pressure generating grooves 14 and one first positive pressure generating groove 15 are arranged on a radial line.

[0029] As shown in FIG. 3, the sliding portion 21 a of the sliding surface 21 of the stationary seal ring 20 has a plurality of second positive pressure generating grooves 24 (24 in the first embodiment) arranged evenly in the circumferential direction on the inner diameter side.

[0030] The portion of the sliding surface 21 other than the second positive pressure generating groove 24 is a flat land 22. The land 22 includes a land 221 on the sliding portion 21 a and a land 222 on the protruding portion 21 b, and the flat surface of the land 221 on the sliding portion 21 a and the flat surface of the land 222 on the protruding portion 21 b are flush and continuous.

[0031] The second positive pressure generating groove 24 has an inner diameter side end, i.e., a relative rotation starting end 24A, which communicates with the inner space S1, and extends in an arc shape from the starting end 24A toward the outer diameter side while inclining downstream in the direction of rotation of the rotary seal ring 10, and an outer diameter side end, i.e., a relative rotation terminal end 24B, which is closed so as not to communicate with the outer space S2. This second positive pressure generating groove 24 has an arc shape that is convex toward the outer diameter side.

[0032] In detail, the second positive pressure generating groove 24 is composed of a bottom surface 24a that is flat from the starting end 24A to the terminal end 24B and parallel to the flat surface of the land 22, a wall portion 24b that extends vertically from the edge of the terminal end 24B of the bottom surface 24a toward the flat surface of the land 22, and side wall portions 24c, 24d that extend vertically from both side edges of the bottom surface 24a toward the flat surface of the land 22.

[0033] The angle formed between the wall portion 24b and the side wall portion 24c is an obtuse angle, and the angle formed between the wall portion 24b and the side wall portion 24d is an acute angle, with the acute angle portion 24f on the side wall portion 24d side of the wall portion 24b being located downstream in the rotational direction of the rotary seal ring 10 than the obtuse angle portion 24e on the side wall portion 24c side of the wall portion 24b. In this embodiment, the acute angle portion 24f is approximately 30 degrees, and the obtuse angle portion 24e is approximately 140 degrees. From the perspective of positive pressure generation capability, the acute angle portion 24f is preferably 20 to 35 degrees.

[0034] A plurality of second positive pressure generating grooves 24 (two in Example 1) are arranged so as to overlap one another in the radial direction when viewed from the axial direction. In other words, a plurality of second positive pressure generating grooves 24 (two in Example 1) are arranged on a radial line.

[0035] As shown in Figure 4, when the sliding surface 21 of the stationary seal ring 20 and the sliding surface 11 of the rotary seal ring 10 are opposed to each other, the first positive pressure generating grooves 14 and 15 are arranged so as to intersect with the second positive pressure generating grooves 24 when viewed from the axial direction. Figure 4 shows the sliding surface 11 of the rotary seal ring 10 as viewed from the axial direction, with the first positive pressure generating grooves 14 and 15 indicated by solid lines and the opposing second positive pressure generating groove 24 indicated by a two-dot dash line.

[0036] Specifically, a plurality of first positive pressure generating grooves 14 and first positive pressure generating grooves 15 are arranged to intersect and face one second positive pressure generating groove 24. That is, a plurality of intersections 16 of the first positive pressure generating grooves 14 and first positive pressure generating grooves 15 and the second positive pressure generating grooves 24 are formed between the sliding surface 11 and the sliding surface 21.

[0037] As shown in FIGS. 4 and 5A, the extension distance L10 of the first positive pressure generating groove 14 is longer than the extension distance L20 of the second positive pressure generating groove 24 (L10>L20).

[0038] For ease of explanation, Figure 5 is a schematic cross-sectional view in which cross sections of one first positive pressure generating groove 14, one first positive pressure generating groove 15, and one second positive pressure generating groove 24 are cut in the longitudinal direction and arranged at the same position in the axial direction.

[0039] The first positive pressure generating groove 14 has a constant depth D1 along its extension direction. The second positive pressure generating groove 24 has a constant depth D2 along its extension direction. The depth D1 of the first positive pressure generating groove 14 is the same as the depth D2 of the second positive pressure generating groove 24 (D1 = D2).

[0040] 4 and 5B, the extension distance L11 of the first positive pressure generating groove 15 is longer than the extension distance L10 of the first positive pressure generating groove 14 and the extension distance L20 of the second positive pressure generating groove 24 (L11 > L10 > L20). In this embodiment, the extension distance L20 of all the second positive pressure generating grooves 24 is shorter than the extension distance L11 of all the first positive pressure generating grooves 15 and the extension distance L10 of all the first positive pressure generating grooves 14, but it is sufficient that the extension distance L20 of at least one second positive pressure generating groove 24 is shorter than the extension distance L11 of at least one first positive pressure generating groove 15 or the extension distance L10 of at least one first positive pressure generating groove 14.

[0041] Specifically, the extension distance L20 of the second positive pressure generating groove 24 is approximately 30% of the extension distance L10 of the first positive pressure generating groove 14 and approximately 25% of the extension distance L11 of the first positive pressure generating groove 15. The inclination angles of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 with respect to the relative rotation direction and the curvature of each groove are approximately the same, but the length of the radial component of the extension distance of each groove (hereinafter sometimes simply referred to as the radial length) is different, so that the radial phases of the terminal end 14B of the first positive pressure generating groove 14, the terminal end 15B of the first positive pressure generating groove 15, and the terminal end 24B of the second positive pressure generating groove 24 are different.

[0042] In this embodiment, the radial length α of the second positive pressure generating groove 24 is exemplified as being approximately 30% of the radial length β of the first positive pressure generating groove 14 and approximately 25% of the radial length β' of the first positive pressure generating groove 15, but this is not limited to this. For example, the radial length α of the second positive pressure generating groove 24 may be 5% or more and 70% or less of the radial length β of the first positive pressure generating groove 14, and preferably 10% or more and 35% or less.

[0043] In this embodiment, since the inclination angle and curvature of each positive pressure generating groove are approximately the same, the extension distance of each groove and the ratio of the radial length of the extension distance are described as being the same, but the inclination angle and curvature of each positive pressure generating groove may be different, in which case it is sufficient that the ratio of the radial length of the second positive pressure generating groove to the radial length of the first positive pressure generating groove has the relationship described above.

[0044] Furthermore, on the sliding surface 11, the radial length δ' of the land 122 located on the outer diameter side of the first positive pressure generating groove 15 is shorter than the radial length δ of the land 121 located on the outer diameter side of the first positive pressure generating groove 14 (δ' < δ). Furthermore, the radial lengths δ and δ' are shorter than the radial length α of the second positive pressure generating groove 24 (δ ≦ α, δ' ≦ α).

[0045] The radial lengths δ, δ' of the lands 121, 122 located on the outer diameter side of the first positive pressure generating grooves 14, 15 can be freely changed, but are preferably no more than twice the radial length α of the second positive pressure generating groove 24 (δ≦2α, δ'≦2α), and more preferably no more than the radial length α (δ≦α, δ'≦α) of the second positive pressure generating groove 24. Furthermore, it is sufficient that the radial length of the land on the sealed fluid space side of at least one first positive pressure generating groove among the plurality of first positive pressure generating grooves provided on the sliding surface of the first sliding component is no more than twice the radial length of at least one second positive pressure generating groove among the plurality of second positive pressure generating grooves provided on the sliding surface of the second sliding component.

[0046] Specifically, if the radial length of the land on the sealed fluid space side of one first positive pressure generating groove is longer than twice the radial length of the second positive pressure generating groove, the weight of the first sliding component increases. For example, when the first sliding component is placed on the second sliding component, the dynamic pressure generating capacity of the second positive pressure generating groove becomes insufficient, making it difficult to lift the sliding surfaces. Furthermore, as the first sliding component becomes larger, the sliding surface of the first sliding component is more likely to tilt significantly relative to the sliding surface of the second sliding component due to vibration, etc., so that a portion of the sliding surface of the first sliding component is significantly separated from one second positive pressure generating groove in the axial direction, making the lift between the sliding surfaces unstable. Therefore, it is preferable that the radial length of the land on the sealed fluid space side of at least one first positive pressure generating groove be no more than twice the radial length of at least one second positive pressure generating groove.

[0047] Furthermore, on the sliding surface 21, the radial length γ of the land 222 of the protruding portion 21b is longer than the radial length δ of the land 121 located on the outer diameter side of the first positive pressure generating groove 14 (δ < γ), and is also longer than the radial length α of the second positive pressure generating groove 24 (α < γ).

[0048] The radial length γ of the land 222 of the protruding portion 21b can be freely changed as long as it is equal to or greater than the radial length α of the second positive pressure generating groove 24 (α≦γ).

[0049] The first positive pressure generating groove 15 has a constant depth D3 along its extension direction. The depth D3 of the first positive pressure generating groove 15 is the same as the depth D1 of the first positive pressure generating groove 14 (D1 = D3). In other words, the depth D3 of the first positive pressure generating groove 15 is the same as the depth D2 of the second positive pressure generating groove 24 (D3 = D2).

[0050] The widths of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 are substantially the same. In addition, the extension distance L11 of the first positive pressure generating groove 15 is longer than the extension distance L10 of the first positive pressure generating groove 14 and the extension distance L20 of the second positive pressure generating groove 24, so the area of ​​the first positive pressure generating groove 15 as viewed in the axial direction is larger than the areas of the first positive pressure generating groove 14 and the second positive pressure generating groove 24. The area of ​​the first positive pressure generating groove 14 as viewed in the axial direction is also larger than the area of ​​the second positive pressure generating groove 24.

[0051] The volumes of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 can be calculated by multiplying the area of ​​the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 when viewed in the axial direction by the depths D1, D2, and D3. As described above, the area of ​​the first positive pressure generating groove 15 when viewed in the axial direction is larger than the area of ​​the first positive pressure generating groove 14, which is larger than the area of ​​the second positive pressure generating groove 24. Furthermore, the depths D1, D2, and D3 are the same. In other words, the volume of the first positive pressure generating groove 15 is larger than the volume of the first positive pressure generating groove 14, which is larger than the volume of the second positive pressure generating groove 24.

[0052] Next, the flow of the atmosphere A during relative rotation between the stationary seal ring 20 and the rotary seal ring 10 will be explained using Figure 6. Note that the flow of the atmosphere A in Figure 6 is shown simply and schematically without specifying the relative rotational speed of the rotary seal ring 10.

[0053] First, we will explain the flow of atmospheric air A within the first positive pressure generating groove 14. As shown in Figure 6(a), when the rotating seal ring 10 rotates relative to the stationary seal ring 20, the atmospheric air A within the first positive pressure generating groove 14 moves from the starting end 14A toward the ending end 14B as shown by the white arrow L1.

[0054] The pressure of the air A moving toward the end 14B is increased at and near the acute angle 14f of the wall portion 14b of the first positive pressure generating groove 14, and the air A flows out between the sliding surfaces 11 and 21 as shown by the white arrow L2. That is, positive pressure is generated at and near the acute angle 14f.

[0055] The atmosphere A in the first positive pressure generating groove 14 indicated by the white arrow L2 acts to push the sealed fluid F near the end 14B of the first positive pressure generating groove 14 back toward the outer space S2, so that the sealed fluid F does not leak into the inner space S1.

[0056] Next, we will explain the flow of atmospheric air A within the first positive pressure generating groove 15. When the rotating seal ring 10 rotates relative to the stationary seal ring 20, the atmospheric air A within the first positive pressure generating groove 15 moves from the starting end 15A toward the ending end 15B as shown by the white arrow L3.

[0057] The pressure of the air A moving toward the end 15B is increased at and near the acute angle 15f of the wall 15b of the first positive pressure generating groove 15, and the air A flows out between the sliding surfaces 11 and 21 as shown by the white arrow L4. That is, positive pressure is generated at and near the acute angle 15f.

[0058] The atmosphere A in the first positive pressure generating groove 15 indicated by the white arrow L4 acts to push back the sealed fluid F near the end 15B of the first positive pressure generating groove 15 toward the outer space S2, so that the sealed fluid F does not leak into the inner space S1.

[0059] Next, we will explain the flow of atmospheric air A within the second positive pressure generating groove 24. As shown in Figure 6(b), when the rotating seal ring 10 rotates relative to the stationary seal ring 20, atmospheric air A within the second positive pressure generating groove 24 moves from the starting end 24A toward the ending end 24B, as shown by the white arrow L5.

[0060] The pressure of the air A moving toward the end 24B is increased at and near the acute angle 24f of the wall portion 24b of the second positive pressure generating groove 24, and the air A flows out between the sliding surfaces 11 and 21 as shown by the white arrow L6. That is, positive pressure is generated at and near the acute angle 24f.

[0061] The atmosphere A in the second positive pressure generating groove 24 indicated by the white arrow L6 acts to push the sealed fluid F near the end 24B of the second positive pressure generating groove 24 back toward the outer space S2, so that the sealed fluid F does not leak into the inner space S1.

[0062] Next, the change in the force separating the sliding surfaces 11, 21 will be described with reference to Fig. 7. Note that the force generated in the first positive pressure generating groove 14 and the second positive pressure generating groove 24 is shown here, and the force generated in the first positive pressure generating groove 15 is not shown.

[0063] First, when the general industrial machine is not in operation and the rotary seal ring 10 is not rotating, the spring 2 urges the stationary seal ring 20 toward the rotary seal ring 10, so the sliding surfaces 11, 21 are in contact with each other, and almost no sealed fluid F leaks between the sliding surfaces 11, 21 into the internal space S1.

[0064] At low relative rotation speeds immediately after the rotating seal ring 10 begins to rotate relative to the stationary seal ring 20, as shown in Figure 7(a), positive pressure is generated at the end 24B of the second positive pressure generating groove 24, which has a capacity smaller than the capacity of the first positive pressure generating groove 14.

[0065] The first force F1 caused by the positive pressure generated at the end 24B of the second positive pressure generating groove 24 causes a slight separation Δa between the sliding surfaces 11 and 21. As a result, the sealed fluid F flows from the outer space S2 to the outer diameter side between the sliding surfaces 11 and 21. The presence of the sealed fluid F between the sliding surfaces 11 and 21 improves lubrication even at low relative rotational speeds, thereby suppressing wear between the sliding surfaces 11 and 21. Furthermore, since the floating distance between the sliding surfaces 11 and 21 is small, the sealed fluid F does not leak into the inner space S1.

[0066] On the other hand, because the capacity of the first positive pressure generating groove 14 is larger than the capacity of the second positive pressure generating groove 24, at low relative rotation speeds between the rotary seal ring 10 and the stationary seal ring 20, the atmosphere A does not become sufficiently dense in the first positive pressure generating groove 14 and high positive pressure is not generated, and the second force F2 (not shown in FIG. 7A ) due to the positive pressure generated by the first positive pressure generating groove 14 is relatively smaller than the first force F1. Therefore, at low relative rotation speeds of the rotary seal ring 10, the first force F1 mainly serves to separate the sliding surfaces 11, 21. Note that, because the capacity of the first positive pressure generating groove 15 is larger than the capacity of the second positive pressure generating groove 24, at low relative rotation speeds the force due to the positive pressure generated by the first positive pressure generating groove 15 is relatively smaller than the first force F1.

[0067] 7B, when the relative rotational speed of the rotary seal ring 10 increases, the positive pressure increases at the terminal end 14B of the first positive pressure generating groove 14. At this time, the positive pressure also increases at the terminal end 15B of the first positive pressure generating groove 15, although this is not shown.

[0068] A second force F2, which is the sum of the force due to the positive pressure generated at the end 14B of the first positive pressure generating groove 14 and the force due to the positive pressure also at the end 15B of the first positive pressure generating groove 15, is applied, and the sliding surfaces 11, 21 are further separated by Δb (Δb > Δa) compared to Figure 7(a). As a result, air A inside the first positive pressure generating groove 14 flows mainly between the sliding surfaces 11, 21, as indicated by the white arrow L2.

[0069] Furthermore, the distance between the sliding surfaces 11 and 21 is further increased by Δb (Δb>Δa) compared to FIG. 7A, so that the first force F1' is smaller than that in FIG. 7A.

[0070] When the relative rotational speed of the rotating seal ring 10 increases further and reaches a high relative rotational speed, i.e., a steady operating state, as shown in FIG. 7(c), the amount of atmosphere A drawn into the first positive pressure generating groove 14 (see white arrow L1' in FIG. 7(c)) and the amount of atmosphere A drawn into the first positive pressure generating groove 15 increase further, generating a high positive pressure, increasing the second force F2', and causing a larger separation Δc (Δc > Δb) between the sliding surfaces 11, 21 compared to FIG. 7(b).

[0071] As a result, the atmosphere A in the first positive pressure generating groove 14 and the atmosphere A in the first positive pressure generating groove 15 further flow into the gap between the sliding surfaces 11 and 21 as indicated by the white arrow L2' in comparison with FIG. 7(b).

[0072] The atmosphere A in the first positive pressure generating groove 14 and the atmosphere A in the first positive pressure generating groove 15, as indicated by white arrow L2', act to push back the sealed fluid F near the end 14B of the first positive pressure generating groove 14 and the end 15B of the first positive pressure generating groove 15 (see FIG. 6A) toward the outer space S2. In this way, at high relative rotation speeds, the sealed fluid F between the sliding surfaces 11, 21 is pushed out into the outer space S2, and almost only the atmosphere A remains between the sliding surfaces 11, 21.

[0073] In this embodiment, when the floating distance increases due to the high relative rotation speed of the rotary seal ring 10, the positive pressure generated in the second positive pressure generating groove 24 becomes negligibly small. Therefore, when the rotary seal ring 10 is rotating at a high relative rotation speed, the second force F2' mainly separates the sliding surfaces 11, 21 from each other.

[0074] 4, the sliding surfaces 11, 21 are formed with a plurality of intersections 16 between the first positive pressure generating groove 14 and the second positive pressure generating groove 24, and a plurality of intersections 16 between the first positive pressure generating groove 15 and the second positive pressure generating groove 24. As a result, in addition to the atmosphere A being introduced into the second positive pressure generating groove 24 from the starting end 24A side, the atmosphere A is also introduced from the first positive pressure generating groove 14 through the intersections 16, so that the first force F1 (see FIG. 7) that separates the sliding surfaces 11, 21 can be generated early.

[0075] Next, the change in the intersection position between the first positive pressure generating groove 14 and the second positive pressure generating groove 24 during relative rotation between the stationary seal ring 20 and the rotary seal ring 10 will be described using Figure 8. Note that, for the sake of convenience, the change in the position of the intersection 16 between one first positive pressure generating groove 14 and one second positive pressure generating groove 24 will be described here, and the intersection 16 is illustrated by dots.

[0076] 8A shows a state in which the start end 14A of the first positive pressure generating groove 14 and the start end 24A of the second positive pressure generating groove 24 intersect when viewed in the axial direction. That is, the intersection 16 with the second positive pressure generating groove 24 is located at the start end 14A of the first positive pressure generating groove 14.

[0077] When the rotating seal ring 10 rotates relative to the stationary seal ring 20, the intersection 16 moves toward the terminal end 14B of the first positive pressure generating groove 14 and is positioned toward the longitudinal center of the first positive pressure generating groove 14, as shown in Figure 8 (b).

[0078] At this time, the fluid in the first positive pressure generating groove 14 is collected in the intersection 16 by the side wall portion 24d of the second positive pressure generating groove 24, and the pressure in the intersection 16 is higher than that in the areas other than the intersection 16 in the first positive pressure generating groove 14 and the second positive pressure generating groove 24.

[0079] When the rotary seal ring 10 further rotates relative to the stationary seal ring 20, the intersecting portion 16 further moves toward the terminal end 14B of the first positive pressure generating groove 14 as shown in FIG. 8(c).

[0080] At this time, the mass of fluid collected in the intersection 16 is subjected to shearing forces by the side wall portion 14d of the first positive pressure generating groove 14 and the acute angle portion 24f of the second positive pressure generating groove 24, generating a large positive pressure.

[0081] In this way, the mass of fluid within the intersection 16 is moved from the starting ends 14A, 24A of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 to the ending ends 14B, 24B, and a large positive pressure is generated at the ending end 24B of the second positive pressure generating groove 24, so that the first force F1 (see Figure 7) that separates the sliding surfaces 11, 21 can be generated early.

[0082] Furthermore, when the rotating seal ring 10 rotates relative to the stationary seal ring 20, the fluid in the first positive pressure generating groove 15 can also be taken into the second positive pressure generating groove 24 from the intersection 16 between the first positive pressure generating groove 15 and the second positive pressure generating groove 24, allowing positive pressure to be generated in the second positive pressure generating groove 24 early on.

[0083] Next, the contaminants C that have flowed into the gap between the sliding surfaces 11 and 21 will be described with reference to FIG.

[0084] The sealed fluid F that flows between the sliding surfaces 11, 21 may contain contaminants. These contaminants are mainly present in the lands 12, 22 that are located radially outward of the first positive pressure generating groove 14 and the second positive pressure generating groove 24. As shown by the black arrow C1 in Figure 6(a), the contaminants move circumferentially following the relative rotation direction of the rotary seal ring 10, and are collected in a portion of the first positive pressure generating groove 15 that is located radially outward of the first positive pressure generating groove 14 and the second positive pressure generating groove 24.

[0085] As shown by the black arrow C2 in Fig. 6(a), the contaminants collected in the first positive pressure generating groove 15 move toward the terminal end 15B together with the air A indicated by the white arrow L3 flowing within the first positive pressure generating groove 15. The contaminants are then discharged from the acute angle portion 15f of the first positive pressure generating groove 15 and its vicinity toward the outer diameter side, and as shown by the black arrow C3 in Fig. 6(a), most of them are discharged into the outer space S2. This prevents the contaminants from remaining between the sliding surfaces 11 and 21 for a long period of time.

[0086] Next, a state in which a relative radial positional deviation occurs between the sliding surface 21 of the stationary seal ring 20 and the sliding surface 11 of the rotary seal ring 10 will be described with reference to FIG.

[0087] As mentioned above, the rotary seal ring 10 is attached to the rotating shaft 1 via the bellows 7, and is allowed to move in the axial and radial directions. Therefore, when the rotary seal ring 10 rotates, particularly at high relative rotational speeds, tilt of the rotary seal ring 10 or vibration of the rotating shaft 1 can cause the sliding surface 11 of the rotary seal ring 10 to move radially relative to the sliding surface 21 of the stationary seal ring 20.

[0088] As shown in Figures 9(a) and 9(b), when the sliding surface 11 of the rotating seal ring 10 moves upward relative to the sliding surface 21 of the stationary seal ring 20, the terminal end 14B of the first positive pressure generating groove 14 and the terminal end 15B of the first positive pressure generating groove 15 at the upper part of the sliding surface 11 are located at the protruding portion 21b of the sliding surface 21, and the starting end 14A of the first positive pressure generating groove 14 and the starting end 15A of the first positive pressure generating groove 15 at the lower part of the sliding surface 11 are located partially on the inner diameter side of the sliding surface 21, i.e., in the inner space S1.

[0089] In this way, even if the sliding surface 11 of the rotating seal ring 10 moves radially relative to the sliding surface 21 of the stationary seal ring 20, the terminal end 14B of the first positive pressure generating groove 14 and the terminal end 15B of the first positive pressure generating groove 15 are positioned axially overlapping with the land 222 of the protruding portion 21b and the land 221 of the sliding portion 21a, so positive pressure can be reliably generated in the first positive pressure generating grooves 14, 15.

[0090] Furthermore, the lands 121, 122 located on the outer diameter side of the first positive pressure generating grooves 14, 15 are also arranged axially overlapping with the land 222 of the protruding portion 21b and the land 221 of the sliding portion 21a, so that the area of ​​the lands 121, 122 that receives the reaction force of the positive pressure generated in the first positive pressure generating grooves 14, 15 is not reduced, and an appropriate floating effect can be obtained.

[0091] Furthermore, the terminal end 14B of the first positive pressure generating groove 14 and the terminal end 15B of the first positive pressure generating groove 15 at the upper part of the sliding surface 11 are radially away from the terminal end 24B of the second positive pressure generating groove 24, so that positive pressure can be reliably generated.

[0092] On the other hand, the terminal end 14B of the first positive pressure generating groove 14 and the terminal end 15B of the first positive pressure generating groove 15 at the bottom of the sliding surface 11 move radially closer to the terminal end 24B of the second positive pressure generating groove 24, but since the difference between the radial length β of the first positive pressure generating groove 14 and the radial length α of the second positive pressure generating groove 24 is ensured to be 70% or more of the radial length β of the first positive pressure generating groove 14, the positive pressure of the second positive pressure generating groove 24 does not affect the positive pressure of the first positive pressure generating grooves 14, 15.

[0093] As explained above, the sliding surface 21 of the stationary seal ring 20 and the sliding surface 11 of the rotating seal ring 10 slide against each other with the first positive pressure generating groove 14 and the first positive pressure generating groove 15 intersecting with the second positive pressure generating groove 24, and the intersection 16 between the first positive pressure generating groove 14 and the second positive pressure generating groove 24 and the intersection 16 between the first positive pressure generating groove 15 and the second positive pressure generating groove 24 are connected, so that at low relative rotational speeds, fluid can be taken in not only from the starting end 24A of the second positive pressure generating groove 24, but also from the opposing first positive pressure generating groove 14 and first positive pressure generating groove 15, and the first force F1 can be generated instantly.

[0094] In addition, one second positive pressure generating groove 24 is opposed to multiple first positive pressure generating grooves 14 in an intersecting manner, and when the stationary seal ring 20 and the rotating seal ring 10 rotate relative to each other, fluid can be taken in from multiple first positive pressure generating grooves 14 into each second positive pressure generating groove 24, so that positive pressure can be generated in the second positive pressure generating groove 24 early.

[0095] Furthermore, the first positive pressure generating groove 15 can collect contaminants that have flowed into the outer space S2 side of the terminal end 14B of the first positive pressure generating groove 14 and the terminal end 24B of the second positive pressure generating groove 24 between the sliding surfaces 11, 21 into the first positive pressure generating groove 15 and discharge them from the terminal end 15B into the outer space S2. Changing the length of the first positive pressure generating groove 15 can improve the effect of discharging contaminants.

[0096] The first positive pressure generating groove 15 is a positive pressure generating groove that generates a positive pressure. In this way, the positive pressure generated in the first positive pressure generating groove 15 can discharge the contaminants C from the first positive pressure generating groove 15 and can also be used as a force that separates the sliding surfaces 11, 21 from each other.

[0097] Furthermore, since the sliding surface 21 of the stationary seal ring 20 has a protruding portion 21b that protrudes toward the outer diameter side, relative radial positional deviation between the sliding surface 11 of the rotating seal ring 10 and the sliding surface 21 of the stationary seal ring 20 is permitted at high relative rotational speeds, and positive pressure can be reliably generated in the first positive pressure generating grooves 14, 15 at high relative rotational speeds.

[0098] Furthermore, since the protruding portion 21b of the stationary seal ring 20 is a flat surface, i.e., no grooves or recesses are formed, positive pressure can be reliably generated in the first positive pressure generating grooves 14, 15 over a wide circumferential range when there is a relative radial misalignment between the sliding surface 11 of the rotating seal ring 10 and the sliding surface 21 of the stationary seal ring 20.

[0099] Furthermore, the flat surface of the land 221 of the sliding portion 21a of the stationary seal ring 20 and the flat surface of the land 222 of the protruding portion 21b are flush and continuous, so that the sliding surfaces 11 and 21 can move smoothly relative to each other in the radial direction, and since no grooves, recesses, etc. are formed, positive pressure can be reliably generated in the first positive pressure generating grooves 14, 15.

[0100] Furthermore, the radial length γ of the land 222 of the protruding portion 21b is longer than the radial length α of the second positive pressure generating groove 24; in other words, the radial length γ of the land 222 is ensured to be equal to or greater than the radial length α of the second positive pressure generating groove 24, so that a large relative radial positional deviation between the rotating seal ring 10 and the stationary seal ring 20 can be tolerated during relative rotation.

[0101] Furthermore, the radial lengths δ, δ' of the lands 121, 122 located on the outer diameter side of the first positive pressure generating grooves 14, 15 are shorter than the radial length γ of the land 222 of the protruding portion 21b. This allows the diameter of the rotary seal ring 10 to be kept to the minimum diameter that ensures the floating effect of the first positive pressure generating grooves 14, 15, while the protruding portion 21b allows for relative radial misalignment between the rotary seal ring 10 and the stationary seal ring 20 during relative rotation, so the diameters of the rotary seal ring 10 and the stationary seal ring 20 can be made compact. In other words, an appropriate dynamic pressure can be generated in the first positive pressure generating grooves 14, 15, and the first positive pressure generating grooves 14, 15 communicate with the outer space S2, thereby preventing the sealed fluid F from leaking into the inner space S1 through the first positive pressure generating grooves 14, 15 and the second positive pressure generating groove 24.

[0102] Furthermore, the rotary seal ring 10, which is prone to radial displacement, is provided with first positive pressure generating grooves 14, 15 having a relatively long radial length, and the opposing stationary seal ring 20 is provided with a protruding portion 21b, so radial displacement of the rotary seal ring 10 is tolerated, and positive pressure can be reliably generated in the first positive pressure generating grooves 14, 15 at high relative rotational speeds.

[0103] Furthermore, the volume of the first positive pressure generating groove 14 is larger than the volume of the second positive pressure generating groove 24. As a result, when the relative rotational speed between the stationary seal ring 20 and the rotary seal ring 10 is low, the sliding surfaces 11, 21 are separated from each other by a first force F1 caused by a positive pressure generated by the atmosphere A in the second positive pressure generating groove 24. Furthermore, as the relative rotational speed between the stationary seal ring 20 and the rotary seal ring 10 increases, the second force F2 caused by a positive pressure generated by the atmosphere A in the first positive pressure generating groove 14 increases, and when the relative rotational speed between the stationary seal ring 20 and the rotary seal ring 10 becomes sufficiently high, the second force F2 becomes larger than the first force F1, and the sliding surfaces 11, 21 are separated from each other by the second force F2. This makes it possible to suppress wear between the sliding surfaces 11, 21 over a range from low relative rotational speeds between the stationary seal ring 20 and the rotary seal ring 10 to high relative rotational speeds.

[0104] Furthermore, the volume of the first positive pressure generating groove 15 is larger than the volume of the first positive pressure generating groove 14. With this, when the relative rotation speed between the stationary seal ring 20 and the rotating seal ring 10 is high, a larger positive pressure can be generated than in the first positive pressure generating groove 14 and the second positive pressure generating groove 24, making it easier to discharge the contaminants C to the external space S2.

[0105] Furthermore, since the number of first positive pressure generating grooves 15 is smaller than that of first positive pressure generating grooves 14, the separation of the sliding surfaces 11, 21, which is mainly caused by the second force F2', is not hindered.

[0106] Furthermore, since the first positive pressure generating grooves 15 are evenly distributed in the circumferential direction, the positive pressure generated in the first positive pressure generating grooves 15 is generated in a balanced manner in the circumferential direction of the sliding surfaces 11, 21, so as not to hinder the separation of the sliding surfaces 11, 21.

[0107] Furthermore, the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 are spiral grooves that extend at an incline in the circumferential direction from the inner space S1 side toward the outer diameter side. This allows many first positive pressure generating grooves 14, first positive pressure generating grooves 15, and second positive pressure generating grooves 24 to be arranged on each sliding surface 11, 21 of the stationary seal ring 20 and the rotary seal ring 10, thereby providing a high degree of freedom in design.

[0108] Furthermore, since the terminal ends 14B, 15B of the first positive pressure generating grooves 14, 15 are located on the outer diameter side of the terminal end 24B of the second positive pressure generating groove 24, the positive pressure generated at the terminal ends 14B, 15B and the positive pressure generated at the terminal end 24B do not interfere with each other.

[0109] Specifically, the difference between the radial length β of the first positive pressure generating groove 14 and the radial length α of the second positive pressure generating groove 24 is ensured to be 70% or more of the radial length β of the first positive pressure generating groove 14, so that even under normal conditions or when there is a radial positional deviation, the positive pressure of the second positive pressure generating groove 24 and the positive pressure of the first positive pressure generating grooves 14, 15 do not interfere with each other, and the sliding surfaces can be smoothly separated from each other from low relative rotation speeds to high relative rotation speeds.

[0110] Furthermore, the radial length α of the second positive pressure generating groove 24 is shorter than the radial lengths β, β' of the first positive pressure generating grooves 14, 15, and the radial lengths δ, δ' of the lands 121, 122 located on the outer diameter side of the first positive pressure generating grooves 14, 15 are shorter than the radial length α of the second positive pressure generating groove 24 (δ < α < β, δ' < α < β'). Therefore, a large proportion of the first positive pressure generating grooves 14, 15 in the sliding surface 11 can be ensured, and the positive pressure generating effect of the first positive pressure generating grooves 14, 15 can be reliably exerted at high relative rotational speeds.

[0111] In the first embodiment, the protruding portion 21b is a flat surface, but the present invention is not limited to this and a recess such as a groove may be provided. In this case, the contaminants discharged from the first positive pressure generating groove 15 can be collected in the recess.

[0112] Furthermore, in the first embodiment, the land 221 of the sliding portion 21a is a flat surface, but it may be provided with a recess such as a dimple, and dynamic pressure may be generated at the recess during relative rotation.

[0113] Furthermore, in the first embodiment, the proportion of the radial lengths β, β' of the first positive pressure generating grooves 14, 15 on the sliding surface 11 is approximately 70 to 90% of the radial length of the sliding surface 11, but it may be at least 50% or more of the radial length of the sliding surface 11. In this way, if the proportion of the first positive pressure generating grooves 14, 15 on the sliding surface 11 is 50% or more, the positive pressure generating effect of the first positive pressure generating grooves can be reliably exhibited at high relative rotational speeds.

[0114] Next, a pair of sliding components according to a second embodiment will be described with reference to Fig. 10. Note that the description of the same configuration as in the first embodiment will be omitted.

[0115] 10 , the depth D1' of the first positive pressure generating groove 140 of the rotating seal ring 100 is deeper than the depth D2' of the second positive pressure generating groove 240 of the stationary seal ring 200. This allows a large amount of air A to be introduced from the deeper first positive pressure generating groove 140 to the second positive pressure generating groove 240 at low relative rotation speeds, so the sliding surfaces can be separated in a short time. Furthermore, because the first positive pressure generating groove 140 has a large volume, a sufficient floating effect can be obtained at high relative rotation speeds.

[0116] In this way, the depth D1' of the first positive pressure generating groove 140 and the depth D2' of the second positive pressure generating groove 240 may be made different to increase the difference in strength of the positive pressure generated in the first positive pressure generating groove 140 and the second positive pressure generating groove 240.

[0117] Next, a pair of sliding components according to a third embodiment will be described with reference to Fig. 11. Note that the description of the same configuration as in the first embodiment will be omitted.

[0118] As shown in FIG. 11, first positive pressure generating grooves 141 and first positive pressure generating grooves 151 are arranged alternately in the circumferential direction on the sliding surface 111 of the rotary seal ring 101 .

[0119] As a result, on the sliding surface 111, contaminants present on the outer diameter side of one of the first positive pressure generating grooves 141 are discharged into the external space S2 by the adjacent first positive pressure generating groove 151 on the downstream side in the relative rotation direction of the rotating seal ring 10.

[0120] Next, a pair of sliding components according to a fourth embodiment will be described with reference to Fig. 12. Note that the description of the same configuration as in the first embodiment will be omitted.

[0121] 12 , first positive pressure generating grooves 152 (six in this embodiment) are equally spaced in the circumferential direction on the sliding surface 112 of the rotary seal ring 102. Furthermore, first positive pressure generating grooves 142 a, 142 b, and 142 c are arranged between adjacent first positive pressure generating grooves 152 in the circumferential direction.

[0122] The first positive pressure generating groove 142a is positioned downstream of the first positive pressure generating grooves 142b, 142c in the relative rotation direction of the rotary seal ring 10, the first positive pressure generating groove 142c is positioned upstream of the first positive pressure generating grooves 142a, 142b in the relative rotation direction of the rotary seal ring 10, and the first positive pressure generating groove 142b is positioned between the first positive pressure generating grooves 142a, 142c.

[0123] The first positive pressure generating grooves 142a, 142b, and 142c are shorter than the first positive pressure generating groove 152. The first positive pressure generating grooves 142a and 142c have the same length. The first positive pressure generating groove 142b is shorter than the first positive pressure generating grooves 142a and 142c.

[0124] Contaminants present on the outer diameter side of first positive pressure generating groove 142b are collected in first positive pressure generating groove 142c, then discharged toward first positive pressure generating groove 152 on the downstream side of the relative rotation, and then discharged from first positive pressure generating groove 152 into outer space S2. In this way, contaminants on the inner diameter side of sliding surface 112, i.e., at a position away from outer space S2, are discharged into outer space S2 through first positive pressure generating groove 142c and first positive pressure generating groove 152.

[0125] Furthermore, a first positive pressure generating groove 142a having the same length as first positive pressure generating groove 142c is provided downstream of first positive pressure generating groove 142b in the relative rotation direction. As a result, the terminal ends of first positive pressure generating grooves 142a, 142b, 142c and the terminal end of first positive pressure generating groove 152 are arranged in a balanced manner in the circumferential and radial directions of sliding surface 112, thereby enabling a balanced separation between the sliding surfaces.

[0126] In the fourth embodiment, the rotary seal ring 102 has first positive pressure generating grooves 142a, 142b, 142c of different lengths and first positive pressure generating groove 152. In this case, the first positive pressure generating groove 152 with the longest extension distance functions as one groove, and the other first positive pressure generating grooves 142a, 142b, 142c that are shorter than first positive pressure generating groove 152 function as other grooves.

[0127] Next, a pair of sliding components according to a fifth embodiment will be described with reference to Fig. 13. Note that the description of the same configuration as in the first embodiment will be omitted.

[0128] As shown in FIG. 13, in addition to the first positive pressure generating grooves 14 and 15, a plurality of dynamic pressure generating mechanisms 17 (three in this embodiment) are provided on the sliding surface 113 of the rotary seal ring 103.

[0129] The dynamic pressure generating mechanism 17 is composed of a fluid inlet groove 17a and a Rayleigh step 17b. The fluid inlet groove 17a extends radially so as to communicate with the outer space S2 but not with the inner space S1. The Rayleigh step 17b extends circumferentially from the inner diameter side of the fluid inlet groove 17a in a counterclockwise direction on the page of Figure 13, i.e., toward the downstream side of the relative rotation of the rotary seal ring 10, concentric with the rotary seal ring 103.

[0130] This allows for low friction between the sliding surfaces using the atmosphere A by the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24, as well as liquid lubrication using the sealed fluid F by the dynamic pressure generating mechanism 17.

[0131] In the above-described first to fifth embodiments, the sliding surface of the stationary seal ring is provided with second positive pressure generating grooves of the same length, but, for example, as shown in Fig. 14, second positive pressure generating grooves 240a, 240b of different lengths may be provided on the sliding surface of the stationary seal ring 200. The radial length of the second positive pressure generating groove 240b is longer than the radial length of the second positive pressure generating groove 240a. In this case, it is sufficient that the radial length of the second positive pressure generating groove 240b is 70% or less of the radial length of the first positive pressure generating groove 15.

[0132] In addition, in the above-described first to fifth embodiments, the leakage side is described as the inner space and the sealed fluid side is described as the outer space. However, for example, as shown in FIG. 15 , the inner space S1 may be filled with the sealed fluid F, and the outer space S2 may contain the atmosphere A. In this case, it is sufficient that the first positive pressure generating groove 143 and the first positive pressure generating groove 153 of the rotary seal ring 104 communicate with the outer space S2 but not with the inner space S1. Furthermore, it is sufficient that the second positive pressure generating groove 243 of the stationary seal ring 204 also communicate with the outer space S2 but not with the inner space S1. Furthermore, it is sufficient that the protruding portion 213b protrudes further inward than the inner diameter of the rotary seal ring 104.

[0133] Furthermore, in the above-described first to fifth embodiments, the rotary seal ring is illustrated as the first sliding component and the static seal ring is illustrated as the second sliding component. However, as shown in FIGS. 16 and 17, for example, the rotary seal ring 300 may be the second sliding component and the static seal ring 400 may be the first sliding component.

[0134] Specifically, as shown in Figure 16, a plurality of second positive pressure generating grooves 302 of the same length are formed in the circumferential direction on the sliding surface 301 of the rotary seal ring 300. Also, as shown in Figure 17, a plurality of first positive pressure generating grooves 402 as other grooves and a plurality of first positive pressure generating grooves 403 as one groove are provided on the sliding surface 401 of the stationary seal ring 400.

[0135] Even in this case, even if the rotary seal ring 300 and the stationary seal ring 400 are relatively misaligned in the radial direction, the protruding portion 321b of the rotary seal ring 300 can reliably generate positive pressure in the first positive pressure generating grooves 402, 403.

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

[0138] Furthermore, in the above-described Examples 1 to 5, an example was given in which the first sliding component is provided with a plurality of types of first positive pressure generating grooves with different lengths, but this is not limited to this. For example, as shown in FIG. 18, the plurality of first positive pressure generating grooves 160 provided in the rotary seal ring 105 may all have the same length.

[0139] Furthermore, in Examples 1 to 5, a configuration was exemplified in which the degree of inclination in the circumferential direction of the first positive pressure generating groove and the second positive pressure generating groove as viewed from each sliding surface is approximately the same, but the degree of inclination in the circumferential direction may be different.

[0140] Furthermore, in Examples 1 to 5, a configuration was exemplified in which a plurality of first positive pressure generating grooves are opposed to one second positive pressure generating groove so as to intersect with each other, but it is also possible for one first positive pressure generating groove to be opposed to one second positive pressure generating groove so as to intersect with each other.

[0141] Furthermore, in the above-described Examples 1 to 5, the width of the first positive pressure generating groove and the width of the second positive pressure generating groove are exemplified, but the width of the first positive pressure generating groove may be formed larger than the width of the second positive pressure generating groove, as long as the volume of the first positive pressure generating groove is larger than the volume of the second positive pressure generating groove.

[0142] In addition, in Examples 1 to 5, the first positive pressure generating groove and the second positive pressure generating groove are spiral grooves, but the present invention is not limited to this, and for example, one or both of the first positive pressure generating groove and the second positive pressure generating groove may be Rayleigh steps. In other words, it is sufficient that the first positive pressure generating groove and the second positive pressure generating groove face each other so as to intersect at least partially.

[0143] Furthermore, in Examples 1 to 5, the cross-sectional shapes of the first positive pressure generating groove and the second positive pressure generating groove are exemplified as being constant in the longitudinal direction, but, for example, steps or inclined surfaces may be formed on the bottom surfaces of the first positive pressure generating groove and the second positive pressure generating groove.

[0144] 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.

[0145] In addition, in the above-described first to fifth embodiments, the sealed fluid F has been described as a high-pressure liquid, but it is not limited to this and may be a gas or a low-pressure liquid, or may be a mist-like mixture of liquid and gas.

[0146] Furthermore, in the above-described Examples 1 to 5, the fluid on the leakage side was described as being the 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.

[0147] REFERENCE SIGNS LIST 10 Rotating seal ring (first sliding component) 11 Sliding surface 12 Land 14, 15 First positive pressure generating groove 16 Intersection 20 Stationary seal ring (second sliding component) 21 Sliding surface 21a Sliding portion 21b Projection 22 Land 24 Second positive pressure generating groove 121, 122 Land 221, 222 Land A Atmosphere C Contaminant F Sealed fluid F1 First force F2 Second force S1 Inner space (leakage side space) S2 Outer space (sealed fluid space)

Claims

1. A pair of sliding parts arranged at a location of relative rotation of a rotary machine, with sliding surfaces sliding relative to each other, wherein the sliding surface of a first sliding part is provided with a first positive pressure generating groove that communicates with a space on the leakage side and has a closed terminal end that extends in the direction of relative rotation of a second sliding part, and the sliding surface of the second sliding part is provided with a second positive pressure generating groove that communicates with the space on the leakage side and has a closed terminal end that extends in the direction of relative rotation of the first sliding part, the sliding surfaces of the first sliding part and the second sliding part slide crosswise so that at least a portion of the first positive pressure generating groove and the second positive pressure generating groove overlap, the first positive pressure generating groove has a terminal end that is located closer to the sealed fluid space than the terminal end of the second positive pressure generating groove, and the radial length of the second positive pressure generating groove is 5% or more and 70% or less of the radial length of the first positive pressure generating groove.

2. A pair of sliding components according to claim 1, wherein the radial length of the second positive pressure generating groove is 10% or more and 35% or less of the radial length of the first positive pressure generating groove.

3. A pair of sliding elements according to claim 1, wherein the radial length of the land on the sealed fluid space side of the first positive pressure generating groove on the sliding surface of the first sliding element is not more than twice the radial length of the second positive pressure generating groove.

4. A pair of sliding components according to claim 1, wherein the first sliding component is a rotary seal ring fixed to a rotary shaft, and the second sliding component is a stationary seal ring fixed to a housing.

5. A pair of sliding components according to any one of claims 1 to 4, wherein the first positive pressure generating groove and the second positive pressure generating groove are spiral grooves extending from the leakage side space toward the sealed fluid side space at an angle from the upstream side of relative rotation to the downstream side of relative rotation.

Images