A pair of sliding parts

Abstract

A pair of sliding components is provided which can suppress wear between the sliding surfaces from the start of relative rotation to high-speed rotation, and which can prevent leakage of a sealed fluid.　On the sliding surface 21 of a second sliding component 20, multiple second positive pressure generating grooves 24 are provided which communicate with a leak-side space S1, extend in the direction of relative rotation of the second sliding component 10 and have a closed end 24B; on the sliding surface 11 of a first sliding component 10, multiple first positive pressure generating grooves 14 are provided which communicate with the leak-side space S1, extend in the direction of relative rotation of the second sliding component 20 and have a closed end 14B; the sliding surface 11 and the sliding surface 21 slide intersecting each other such that at least part of the first positive pressure generating grooves 14 and the second positive pressure generating grooves 24 overlap.

Description

[Technical Field]

[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. [Background technology]

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

[0003] For example, the mechanical seal disclosed in Patent Document 1 comprises 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 is provided with 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. According to this, 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 62-31775 (pages 2 and 3, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[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 high-speed rotation state above 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 from the start of relative rotation through to high-speed rotation, and can also suppress leakage of the sealed fluid. [Means for solving the problem]

[0007] In order to solve the above problems, a pair of sliding components according to the present invention comprises: A pair of sliding components that are arranged at relative rotational positions of a rotary machine and have sliding surfaces that slide relative to each other, a sliding surface of the first sliding element is provided with a plurality of first positive pressure generating grooves that communicate with the leakage side space, extend in the relative rotation direction of the second sliding element, and have closed terminal ends; a sliding surface of the second sliding element is provided with a plurality of second positive pressure generating grooves that communicate with the leakage side space, extend in the relative rotation direction of the first sliding element, and have closed terminal ends; The sliding surface of the first sliding component and the sliding surface of the second sliding component slide across each other so that at least a portion of the first positive pressure generating groove and the second positive pressure generating groove overlap each other. According to this, the portion where the first positive pressure generating groove and the second positive pressure generating groove intersect is connected, so that when the relative rotation speed is low, in addition to the connecting portion to the space on the leakage side of the first positive pressure generating groove and the second positive pressure generating groove, fluid can be taken in from the opposing first positive pressure generating groove or second positive pressure generating groove, and a force that separates the sliding surfaces can be instantly generated.

[0008] A plurality of the second positive pressure generating grooves may be disposed opposite each of the first positive pressure generating grooves so as to intersect with each other. According to this, when the pair of sliding parts rotate relative to each other, fluid can be taken into each first positive pressure generating groove from multiple second positive pressure generating grooves, so that positive pressure can be generated in the first positive pressure generating groove early.

[0009] The first positive pressure generating groove and the second positive pressure generating groove may extend obliquely in the circumferential direction from the leakage side toward the sealed fluid side. This allows a large number of first positive pressure generating grooves or second positive pressure generating grooves to be arranged on each sliding surface of the first sliding component and the second sliding component, thereby providing a high degree of freedom in design.

[0010] The terminal end of the first positive pressure generating groove and the terminal end of the second positive pressure generating groove may be offset from each other in the radial direction. With this, the positive pressure generated at the end portion of the first positive pressure generating groove and the positive pressure generated at the end portion of the second positive pressure generating groove do not interfere with each other, so that the sliding surfaces can be stably separated from each other.

[0011] The volume of the first positive pressure generating groove may be smaller than the volume of the second positive pressure generating groove. According to this, because the volume of the first positive pressure generating groove is smaller than the volume of the second positive pressure generating groove, when the relative rotation speed of the sliding elements is low, the first force caused by the positive pressure generated by the fluid in the first positive pressure generating groove mainly separates the sliding surfaces. As the relative rotation speed of the sliding elements increases, the second force caused by the positive pressure generated by the fluid in the second positive pressure generating groove increases. When the relative rotation speed of the sliding elements becomes sufficiently high, the second force becomes larger than the first force, and the sliding surfaces are mainly separated by the second force, thereby suppressing wear between the sliding surfaces from low to high relative rotation speeds of the pair of sliding elements. Furthermore, when the relative rotation speed of the sliding elements is high, the gap formed between the sliding surfaces becomes larger, making it difficult for positive pressure to be generated in the first positive pressure generating groove. Therefore, the sliding surfaces can be stably separated by the second force caused by the positive pressure generated in the second positive pressure generating groove mainly from high rotation speeds of the pair of sliding elements. Therefore, wear can be suppressed by separating the sliding surfaces from each other from the start of relative rotation of the pair of sliding elements to high rotation speeds.

[0012] The first positive pressure generating groove may have a shorter extension distance than the second positive pressure generating groove. With this, the terminal end of the first positive pressure generating groove is closer to the starting end communicating with the leakage side space than the terminal end of the second positive pressure generating groove, so positive pressure can be generated in the first positive pressure generating groove early.

[0013] The depth of the first positive pressure generating groove may be shallower than the depth of the second positive pressure generating groove. This allows positive pressure to be generated in the first positive pressure generating groove early.

[0014] The first positive pressure generating groove may be inclined more in the circumferential direction than the second positive pressure generating groove. According to this, when the sliding parts start to rotate relative to each other, it is easier to introduce fluid into the first positive pressure generating groove than into the second positive pressure generating groove, so that positive pressure can be generated in the first positive pressure generating groove early.

[0015] The width of the first positive pressure generating groove may be smaller than the width of the second positive pressure generating groove. According to this, since the width dimension of the first positive pressure generating groove is smaller than the width dimension of the second positive pressure generating groove, positive pressure can be generated in the first positive pressure generating groove early.

[0016] The first sliding component may be a stationary seal ring, and the second sliding component may be a rotary seal ring. With this, because the first sliding component is a stationary seal ring, the positive pressure generated in the first positive pressure generating groove during low-speed rotation is stabilized. Also, because the second sliding component is a rotary seal ring, fluid can be easily introduced into the second positive pressure generating groove, and the transition to separation of the sliding surfaces, mainly caused by the second force, can be achieved quickly. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a vertical cross-sectional view showing an example of a mechanical seal according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a view of the sliding surface of the rotary seal ring as viewed from the axial direction. [Figure 3]FIG. 4 is a view of the sliding surface of the stationary seal ring as viewed from the axial direction. [Figure 4] 1 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 are arranged opposite each other, where a first positive pressure generating groove of the stationary seal ring is indicated by a two-dot dashed line. [Figure 5] FIG. 3 is a cross-sectional view schematically showing a first positive pressure generating groove and a second positive pressure generating groove. [Figure 6] 1A is an explanatory diagram of the movement of fluid in the second positive pressure generating groove as viewed from the axial direction, and FIG. 1B is an explanatory diagram of the movement of fluid in the first positive pressure generating groove as viewed from the axial direction. [Figure 7] 5(a) to 5(c) are cross-sectional views schematically showing the state of a pair of sliding elements at each relative rotation speed. [Figure 8] 1 is an explanatory diagram showing a change in the position of an intersection of a first positive pressure generating groove and a second positive pressure generating groove, where only one intersection of a first positive pressure generating groove and a second positive pressure generating groove is shown. [Figure 9] 10 is an explanatory view showing a first modified example of the first positive pressure generating groove of the first embodiment. FIG. [Figure 10] FIG. 6 is an explanatory view schematically showing an example of a mechanical seal according to a second embodiment of the present invention. [Figure 11] FIG. 10 is an explanatory view schematically showing an example of a mechanical seal according to a third embodiment of the present invention. [Figure 12] FIG. 10 is an explanatory view schematically showing an example of a mechanical seal according to a fourth embodiment of the present invention. [Figure 13] FIG. 10 is an explanatory view showing a second modified example of the first positive pressure generating groove of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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. [Example]

[0019] A pair of sliding elements according to a first embodiment will be described with reference to Figs. 1 to 7. In this embodiment, the pair of sliding elements will be described as mechanical seals. A sealed fluid exists in the outer space of the mechanical seal, and atmospheric air exists 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 formed on the sliding surfaces may be indicated by dots in the drawings.

[0020] 1 is an inside type mechanical seal for general industrial machinery that seals against a sealed fluid F that tends to leak from the outer diameter side toward the inner diameter side of the sliding surface, and has an internal space S1 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.

[0021] The mechanical seal is mainly composed of a rotating seal ring 20 as a second sliding component, which is attached to a sleeve 2 fixed to a rotating shaft 1 and is rotatable together with the rotating shaft 1, and a stationary seal ring 10 as a first sliding component which is non-rotating and axially movable on a seal cover 5 fixed to a housing 4 of the device to which the seal is attached. The static seal ring 10 is urged in the axial direction by a bellows 7, so that the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide closely against each other.

[0022] The stationary seal ring 10 and the rotating seal ring 20 are typically formed from a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but any sliding material used for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, or other sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC consisting of SiC and Si, SiC-TiC, and SiC-TiN. Examples of carbon include a mixture of carbonaceous and graphite materials, resin-molded carbon, and sintered carbon. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), and composite materials can also be used.

[0023] 2, a plurality of second positive pressure generating grooves 24, for example, 24 in Example 1, are evenly arranged in the circumferential direction on the inner diameter side of the sliding surface 21 of the rotary seal ring 20. The portion of the sliding surface 21 other than the second positive pressure generating grooves 24 is a land 22 that forms a flat surface.

[0024] 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 sloping upstream in the direction of rotation of the rotary seal ring 20, 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.

[0025] In detail, the second positive pressure generating groove 24 is composed of a bottom surface 24a that is flat from a starting end 24A to a terminal end 24B and is parallel to the flat surface of the land 22, a wall portion 24b that extends perpendicularly 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 perpendicularly from the side edges of the bottom surface 24a toward the flat surface of the land 22. 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 of the wall portion 24b on the side wall portion 24d side being located further upstream in the rotational direction of the rotary seal ring 20 than the obtuse angle portion 24e of the wall portion 24b on the side wall portion 24c side.

[0026] As viewed from the axial direction, a plurality of second positive pressure generating grooves 24, for example, three grooves in Example 1, are arranged so as to overlap one another in the radial direction. In other words, a plurality of second positive pressure generating grooves 24, for example, three grooves in Example 1, are arranged on a radial line.

[0027] 3, the rotary seal ring 20 slides counterclockwise relative to the stationary seal ring 10 as shown by the arrow, and a plurality of first positive pressure generating grooves 14, for example, 24 in Example 1, are evenly arranged in the circumferential direction on the inner diameter side of the sliding surface 11 of the stationary seal ring 10. The portion of the sliding surface 11 other than the first positive pressure generating grooves 14 is a land 12 forming a flat surface.

[0028] 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 while inclining downstream in the rotation direction of the rotary seal ring 20, and an outer diameter side end, i.e., a relative rotation terminal end 14B, which is closed so as not to communicate with the outer space S2. This first positive pressure generating groove 14 has an arc shape that is convex toward the outer diameter side.

[0029] In detail, the first positive pressure generating groove 14 is composed of a bottom surface 14a that is flat from a starting end 14A to a terminal end 14B and is parallel to the flat surface of the land 12, a wall portion 14b that extends perpendicularly from the edge of the terminal end 14B of the bottom surface 14a toward the flat surface of the land 12, and side wall portions 14c, 14d that extend perpendicularly from the side edges of the bottom surface 14a toward the flat surface of the land 12. 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, with the acute angle portion 14f of the wall portion 14b on the side wall portion 14d side being located downstream in the rotational direction of the rotary seal ring 20 from the obtuse angle portion 14e of the wall portion 14b on the side wall portion 14c side.

[0030] When viewed from the axial direction, a plurality of first positive pressure generating grooves 14, for example, two grooves in Example 1, are arranged so as to overlap in the radial direction. In other words, a plurality of first positive pressure generating grooves 14, for example, two grooves in Example 1, are arranged on a radial line.

[0031] As shown in Figure 4, when the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotary seal ring 20 are opposed to each other, the first positive pressure generating groove 14 and the second positive pressure generating groove 24 are arranged so as to intersect when viewed from the axial direction. Note that Figure 4 illustrates the sliding surface 21 of the rotary seal ring 20 as viewed from the axial direction, with the second positive pressure generating groove 24 indicated by a solid line and the opposing first positive pressure generating groove 14 indicated by a two-dot dash line.

[0032] Specifically, a plurality of second positive pressure generating grooves 24 (five in this embodiment) are arranged to intersect and face one first positive pressure generating groove 14, and a plurality of first positive pressure generating grooves 14 (five in this embodiment) are arranged to intersect and face one second positive pressure generating groove 24. In other words, a plurality of intersections 15 between the first positive pressure generating groove 14 and the second positive pressure generating groove 24 are formed.

[0033] 4 and 5, the length from the start point 14A to the end point 14B of the first positive pressure generating groove 14, i.e., the extension distance L10 of the first positive pressure generating groove 14, is shorter than the length from the start point 24A to the end point 24B of the second positive pressure generating groove 24, i.e., the extension distance L20 of the second positive pressure generating groove 24 (L10 <L20)。

[0034] For ease of explanation, Figure 5 is a schematic cross-sectional view in which cross sections of one first positive pressure generating groove 14 and one second positive pressure generating groove 24 taken in the longitudinal direction are arranged at the same position in the axial direction.

[0035] Specifically, the extension distance L10 of the first positive pressure generating groove 14 is about two-thirds of the extension distance L20 of the second positive pressure generating groove 24.

[0036] That is, the terminal end 24B of the second positive pressure generating groove 24 is disposed on the outer diameter side of the terminal end 14B of the first positive pressure generating groove 14.

[0037] Furthermore, the width dimensions of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 are approximately the same. In other words, the extension distance L10 of the first positive pressure generating groove 14 is shorter than the extension distance L20 of the second positive pressure generating groove 24, and therefore the area of ​​the first positive pressure generating groove 14 as viewed in the axial direction is smaller than the area of ​​the second positive pressure generating groove 24.

[0038] As shown in FIG. 5, the first positive pressure generating groove 14 has a constant depth D1 from the starting end 14A to the ending end 14B.

[0039] The second positive pressure generating groove 24 has a constant depth D2 from the starting end 24A to the ending end 24B. The depth D1 of the first positive pressure generating groove 14 and the depth D2 of the second positive pressure generating groove 24 are the same dimension (D1 = D2).

[0040] The volumes of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 can be found by multiplying the areas of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 when viewed in the axial direction by the depths D1 and D2. As described above, the area of ​​the first positive pressure generating groove 14 when viewed in the axial direction is smaller than the area of ​​the second positive pressure generating groove 24, and the depth D1 of the first positive pressure generating groove 14 and the depth D2 of the second positive pressure generating groove 24 are the same dimension, so the capacity of the first positive pressure generating groove 14 is smaller than the volume of the second positive pressure generating groove 24.

[0041] Furthermore, in this embodiment 1, when the sliding surface 11 is viewed in the axial direction, the degree of circumferential inclination of the first positive pressure generating groove 14 relative to the inner surface of the stationary seal ring 10 is the same as the degree of circumferential inclination of the second positive pressure generating groove 24 relative to the inner surface of the rotating seal ring 20 when the sliding surface 21 is viewed in the axial direction.

[0042] Next, the flow of the atmosphere A during relative rotation between the stationary seal ring 10 and the rotating seal ring 20 will be explained using Figure 6. The flow of the atmosphere A in Figure 6 is shown schematically without specifying the relative rotation speed of the rotating seal ring 20.

[0043] First, we will explain the flow of air A within the second positive pressure generating groove 24. As shown in Figure 6(a), when the rotating seal ring 20 rotates relative to the stationary seal ring 10, air A within the second positive pressure generating groove 24 moves from the starting end 24A toward the ending end 24B as shown by arrow L1.

[0044] 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 arrow L2. That is, positive pressure is generated at and near the acute angle 24f.

[0045] The atmosphere A in the second positive pressure generating groove 24 indicated by the arrow L2 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.

[0046] Next, the flow of atmosphere A within the first positive pressure generating groove 14 will be described. As shown in Figure 6(b), when the rotating seal ring 20 rotates relative to the stationary seal ring 10, atmosphere A within the first positive pressure generating groove 14 receives a shearing force from the sliding surface 21 and moves in the direction of rotation of the rotating seal ring 20, while atmosphere A within the internal space S1 is drawn into the first positive pressure generating groove 14. That is, within the first positive pressure generating groove 14, atmosphere A moves from the starting end 14A toward the ending end 14B, as shown by arrow L3.

[0047] 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 arrow L4. That is, positive pressure is generated at and near the acute angle 14f.

[0048] The atmosphere A in the first positive pressure generating groove 14 indicated by the arrow L4 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.

[0049] Next, the change in the force separating the sliding surfaces 11 and 21 will be described with reference to FIG.

[0050] First, when the general industrial machine is not in operation and the rotary seal ring 20 is not rotating, the stationary seal ring 10 is urged toward the rotary seal ring 20 by the bellows 7, 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.

[0051] At low speeds immediately after the rotating seal ring 20 begins to rotate relative to the stationary seal ring 10, as shown in Figure 7(a), positive pressure is generated at the end 14B of the first positive pressure generating groove 14, which has a capacity smaller than the capacity of the second positive pressure generating groove 24.

[0052] The first force F1 caused by the positive pressure generated at the end 14B of the first positive pressure generating groove 14 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 during low-speed rotation, and suppresses 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.

[0053] On the other hand, because the capacity of the second positive pressure generating groove 24 is larger than the capacity of the first positive pressure generating groove 14, when the relative rotation speed between the rotary seal ring 20 and the stationary seal ring 10 is low, the atmosphere A does not become sufficiently dense in the second positive pressure generating groove 24 and high positive pressure is not generated, and the second force F2 (not shown in FIG. 7(a)) due to the positive pressure generated by the second positive pressure generating groove 24 is relatively smaller than the first force F1. Therefore, when the rotary seal ring 20 is rotating at low speed, the first force F1 mainly serves to separate the sliding surfaces 11, 21 from each other.

[0054] When the relative rotation speed of the rotary seal ring 20 increases, the positive pressure increases at the terminal end 24B of the second positive pressure generating groove 24, as shown in FIG. 7(b).

[0055] A second force F2 is applied by the positive pressure generated at the end 24B of the second positive pressure generating groove 24, and the distance between the sliding surfaces 11 and 21 is further increased by Δb (Δb>Δa) compared to Figure 7(a). As a result, air A in the second positive pressure generating groove 24 flows mainly between the sliding surfaces 11 and 21 as indicated by arrow L2.

[0056] Furthermore, the distance between the sliding surfaces 11 and 21 is further increased by Δb (Δb>Δa) compared to FIG. 7(a), so that the first force F1' is smaller than that in FIG. 7(a).

[0057] When the relative rotational speed of the rotating seal ring 20 increases further and reaches high-speed rotation, i.e., a steady operating state, as shown in Figure 7(c), the amount of atmosphere A drawn into the second positive pressure generating groove 24 (see arrow L1' in Figure 7(c)) increases further, generating a high positive pressure, increasing the second force F2', and causing a larger separation Δc (Δc > Δb) between the sliding surfaces 11 and 21 compared to Figure 7(b).

[0058] As a result, the air A in the second positive pressure generating groove 24 further flows into the gap between the sliding surfaces 11 and 21 as shown by the arrow L2' in comparison with FIG. 7(b).

[0059] The atmosphere A in the second positive pressure generating groove 24 indicated by the arrow L2' acts to push back toward the outer space S2 the sealed fluid F near the end 24B of the second positive pressure generating groove 24. In this way, during high speed rotation, 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.

[0060] In this embodiment, when the floating distance increases due to high speed rotation of the rotary seal ring 20, the positive pressure generated in the first positive pressure generating groove 14 becomes negligibly small. Therefore, when the rotary seal ring 20 rotates at high speed, the second force F2' mainly separates the sliding surfaces 11, 21 from each other.

[0061] Returning to Figure 4, multiple intersections 15 are formed between the first positive pressure generating groove 14 and the second positive pressure generating groove 24, and in addition to air A being introduced into the first positive pressure generating groove 14 from the starting end 14A side, air A is also introduced from the second positive pressure generating groove 24 through the intersections 15, so that the first force F1 (see Figure 7) that separates the sliding surfaces 11, 21 can be generated early.

[0062] 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 10 and the rotating seal ring 20 will be described using Figure 8. For ease of explanation, the change in the position of the intersection 15 between one first positive pressure generating groove 14 and one second positive pressure generating groove 24 will be described, and the intersection 15 is illustrated by dots.

[0063] 8(a) 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 15 with the second positive pressure generating groove 24 is located at the start end 14A of the first positive pressure generating groove 14.

[0064] When the rotating seal ring 20 rotates relative to the stationary seal ring 10, the intersection 15 moves toward the end 14B of the first positive pressure generating groove 14 and is positioned at the longitudinal center of the first positive pressure generating groove 14, as shown in Figure 8(b).

[0065] At this time, the fluid in the second positive pressure generating groove 24 is collected in the intersection 15 by the side wall portion 14d of the first positive pressure generating groove 14, and the pressure in the intersection 15 is higher than that in the areas other than the intersection 15 in the first positive pressure generating groove 14 and the second positive pressure generating groove 24.

[0066] When the rotary seal ring 20 further rotates relative to the stationary seal ring 10, the intersecting portion 15 moves and is positioned at the terminal end 14B of the first positive pressure generating groove 14 as shown in FIG. 8(c).

[0067] At this time, the mass of fluid collected in the intersection 15 is subjected to shearing force by the side wall portion 24d of the second positive pressure generating groove 24 and the acute angle portion 14f of the first positive pressure generating groove 14, generating a large positive pressure.

[0068] In this way, the mass of fluid in the intersection 15 is moved from the starting point 14A of the first positive pressure generating groove 14 to the ending point 14B, and a large positive pressure is generated at the ending point 14B of the first positive pressure generating groove 14, so that the first force F1 (see Figure 7) that separates the sliding surfaces 11 and 21 can be generated early.

[0069] As explained above, the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide against each other with the first positive pressure generating groove 14 and the second positive pressure generating groove 24 intersecting with each other, and the intersection 15 between the first positive pressure generating groove 14 and the second positive pressure generating groove 24 is connected, so that at low relative rotational speeds, fluid can be taken in not only from the starting end 14A of the first positive pressure generating groove 14 but also from the opposing second positive pressure generating groove 24, and the first force F1 can be generated instantly.

[0070] Furthermore, because the volume of the first positive pressure generating groove 14 is smaller than the volume of the second positive pressure generating groove 24, when the relative rotation speed between the stationary seal ring 10 and the rotary seal ring 20 is low, the sliding surfaces 11, 21 are separated from each other by the first force F1 caused by the positive pressure generated by the atmosphere A in the first positive pressure generating groove 14. Furthermore, as the relative rotation speed between the stationary seal ring 10 and the rotary seal ring 20 increases, the second force F2 caused by the positive pressure generated by the atmosphere A in the second positive pressure generating groove 24 increases, and when the relative rotation speed between the stationary seal ring 10 and the rotary seal ring 20 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 at all times from low to high relative rotation speeds between the stationary seal ring 10 and the rotary seal ring 20.

[0071] Furthermore, when the static seal ring 10 and the rotary seal ring 20 are rotating at high relative rotational speeds, the gap formed between the sliding surfaces 11, 21 becomes larger, making it difficult for positive pressure to be generated within the first positive pressure generating groove 14, and the second force F2 due to the positive pressure generated in the second positive pressure generating groove 24 becomes the main force that can stably separate the sliding surfaces 11, 21. Therefore, wear between the sliding surfaces 11, 21 can be suppressed over the entire range from low to high relative rotational speeds between the static seal ring 10 and the rotary seal ring 20.

[0072] In addition, multiple second positive pressure generating grooves 24 intersect with one first positive pressure generating groove 14, and when the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other, atmospheric air A can be taken into the multiple first positive pressure generating grooves 14 from the second positive pressure generating grooves 24, so that the first force F1 can be generated early.

[0073] Furthermore, during relative rotation between the stationary seal ring 10 and the rotating seal ring 20, positive pressure can be continuously generated within the first positive pressure generating groove 14, and the first force F1 can be stably generated.

[0074] Furthermore, the first positive pressure generating grooves 14 and the second positive pressure generating grooves 24 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 and many second positive pressure generating grooves 24 to be arranged on each sliding surface 11, 21 of the stationary seal ring 10 and the rotary seal ring 20, thereby increasing the degree of freedom in design.

[0075] Furthermore, 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 are radially offset, and the positive pressure generated at the terminal end 14B of the first positive pressure generating groove 14 and the positive pressure generated at the terminal end 24B of the second positive pressure generating groove 24 do not interfere with each other, so the sliding surfaces 11, 21 can be stably separated from each other.

[0076] Additionally, the extension distance L10 of the first positive pressure generating groove 14 is shorter than the extension distance L20 of the second positive pressure generating groove 24. As a result, the end 14B of the first positive pressure generating groove 14 is closer to the start 14A that communicates with the internal space S1 than the end 24B of the second positive pressure generating groove 24, so that positive pressure can be generated in the first positive pressure generating groove 14 at an early stage.

[0077] Furthermore, by adjusting the lengths of the first positive pressure generating groove 14 and the second positive pressure generating groove 24, the magnitudes of the first force F1 and the second force F2 can be adjusted, so the depth and width of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 can be made the same dimensions, simplifying the design.

[0078] Furthermore, since the first positive pressure generating groove 14 is provided in the stationary seal ring 10, the positive pressure generated in the first positive pressure generating groove 14 is stable when the rotary seal ring 20 is rotating at low speeds. Furthermore, since the second positive pressure generating groove 24 is provided in the rotary seal ring 20, fluid can be easily introduced into the second positive pressure generating groove 24, and the transition to separation of the sliding surfaces 11, 21, mainly caused by the second force F2, can be achieved quickly.

[0079] In this embodiment 1, the extension distance L10 of the first positive pressure generating groove 14 is approximately 2 / 3 of the extension distance L20 of the second positive pressure generating groove 24, but as shown in Fig. 9, the length of the second positive pressure generating groove 140 of the stationary seal ring 100 may be approximately 1 / 3 of the length of the second positive pressure generating groove 24 (see Fig. 2). In other words, the lengths of the first positive pressure generating groove and the second positive pressure generating groove may be freely changed. [Example]

[0080] Next, a pair of sliding components according to Example 2 will be described with reference to Fig. 10. Note that a description of the same configuration as in Example 1 will be omitted. Note that, for convenience of explanation, Fig. 10 is a schematic cross-sectional view in which cross sections of one row of first positive pressure generating groove and one row of second positive pressure generating groove taken in the longitudinal direction are arranged at the same position in the axial direction.

[0081] As shown in FIG. 10, the second positive pressure generating groove 241 of the rotary seal ring 201 has a constant depth D20 from the starting end 241A to the terminal end 241B.

[0082] Moreover, the first positive pressure generating groove 141 of the stationary seal ring 101 has a constant depth D10 from the starting end 141A to the terminal end 141B.

[0083] The depth D20 of the second positive pressure generating groove 241 is deeper than the depth D10 of the first positive pressure generating groove 141 (D10 <D20)。

[0084] Furthermore, the extension distance L11 of the first positive pressure generating groove 141 and the extension distance L21 of the second positive pressure generating groove 241 are the same (L11=L21). Although not shown, the width dimension of the first positive pressure generating groove 141 and the width dimension of the second positive pressure generating groove 241 are the same.

[0085] That is, since the volume of the first positive pressure generating groove 141 is smaller than the volume of the second positive pressure generating groove 241, when the relative rotation speed between the stationary seal ring 101 and the rotating seal ring 201 is low, the sliding surfaces 111, 211 are separated from each other mainly by a first force (not shown) due to the positive pressure generated in the first positive pressure generating groove 141.

[0086] In addition, since the atmosphere A on the bottom surface 141a side of the first positive pressure generating groove 141 is more likely to receive a shearing force than the atmosphere A on the bottom surface 241a side of the second positive pressure generating groove 241, a positive pressure can be generated in the first positive pressure generating groove 141 at an early stage.

[0087] In addition, in the second embodiment, the form in which the extension distance L11 of the first positive pressure generating groove 141 and the extension distance L21 of the second positive pressure generating groove 241 are the same dimension is illustrated. However, the present invention is not limited to this. It is sufficient that the volume of the first positive pressure generating groove is smaller than the volume of the second positive pressure generating groove. For example, the stationary seal ring may have a first positive pressure generating groove having a length dimension different from that of the second positive pressure generating groove. Further, the rotating seal ring may have a second positive pressure generating groove having a length dimension different from that of the first positive pressure generating groove.

Embodiment

[0088] Next, a pair of sliding parts according to the third embodiment will be described with reference to FIG. 11. In addition, the description of the configuration that is the same as that of the first embodiment will be omitted.

[0089] As shown in FIG. 11, the first positive pressure generating groove 142 of the stationary seal ring 102 is inclined along the circumferential direction more than the second positive pressure generating groove 24 of the rotating seal ring 20.

[0090] In addition, the end 142B of the first positive pressure generating groove 142 and the end 24B of the second positive pressure generating groove 24 are provided at the same position in the radial direction and overlap when viewed from the axial direction.

[0091] In addition, the area R1 of the first positive pressure generating groove 142 viewed from the axial direction is smaller than the area R2 of the second positive pressure generating groove 24 (R1 < R2). Although not shown, the depth of the first positive pressure generating groove 142 and the depth of the second positive pressure generating groove 24 in the present embodiment are the same.

[0092] That is, the volume of the first positive pressure generating groove 142 is smaller than the volume of the second positive pressure generating groove 24. In addition, the area R1 of the first positive pressure generating groove 142 and the area R2 of the second positive pressure generating groove 24 may be the same and the depths may be different.

[0093] As described above, since the first positive pressure generating groove 142 of the stationary seal ring 102 is inclined along the circumferential direction more than the second positive pressure generating groove 24 of the rotating seal ring 20, at the start of relative rotation between the stationary seal ring 102 and the rotating seal ring 20, it is easier to introduce the atmosphere A into the first positive pressure generating groove 142 than into the second positive pressure generating groove 24. Therefore, a positive pressure can be generated early in the first positive pressure generating groove 142.

Embodiment

[0094] Next, a pair of sliding parts according to Embodiment 4 will be described with reference to FIG. 12. Note that the description of the same configuration as that of Embodiment 1 will be omitted. Further, in FIG. 12, the sliding surface of the stationary seal ring as viewed from the axial direction is shown, the first positive pressure generating groove is shown by a solid line, and the opposing second positive pressure generating groove is shown by a two-dot chain line.

[0095] The rotating seal ring 20 (see FIG. 2) has 24 (see FIG. 2) equally distributed second positive pressure generating grooves 24 in the circumferential direction of the sliding surface 11 as described above. As shown in FIG. 12, one second positive pressure generating groove 24 has a circumferential width W2.

[0096] The stationary seal ring 103 has 48 (only a part is shown here) first positive pressure generating grooves 143 formed and equally distributed in the circumferential direction of the sliding surface 131. That is, the number of the first positive pressure generating grooves 143 is twice that of the second positive pressure generating grooves 24.

[0097] The circumferential width W1 of the first positive pressure generating groove 143 is smaller than the circumferential width W2 of the second positive pressure generating groove 24 (W1 < W2), and the separation width W3 between adjacent first positive pressure generating grooves 143 is smaller than the separation width W4 between the second positive pressure generating grooves 24. Thus, the first positive pressure generating grooves 143 can be provided in a number twice that of the second positive pressure generating grooves 24.

[0098] Also, the extending distances of the first positive pressure generating groove 143 and the second positive pressure generating groove 24 are the same. That is, the area of the first positive pressure generating groove 143 as viewed from the axial direction is smaller than the area of the second positive pressure generating groove 24.

[0099] Although not shown, in this embodiment, the depth of the first positive pressure generating groove 143 is the same as the depth of the second positive pressure generating groove 24. In other words, the volume of the first positive pressure generating groove 143 is smaller than the volume of the second positive pressure generating groove 24.

[0100] According to this, since the number of first positive pressure generating grooves 143 is twice that of second positive pressure generating grooves 24, it is possible to generate a first force F1 (not shown here) uniformly around the circumferential direction of the sliding surface 131 of the stationary seal ring 103. Furthermore, since the volume of the first positive pressure generating grooves 143 can be made smaller than the volume of the second positive pressure generating grooves 24, it is possible to generate positive pressure in the first positive pressure generating grooves 143 early.

[0101] In this fourth embodiment, an example has been given in which the sliding surface 131 of the stationary seal ring 103 has twice the number of first positive pressure generating grooves 143 as the number of second positive pressure generating grooves 24, but for example, as shown in Fig. 13, the sliding surface 151 of the stationary seal ring 104 may have the same number of first positive pressure generating grooves 143 as the second positive pressure generating grooves 24, for example 24. In addition, if the volume of the second positive pressure generating grooves is smaller than the volume of the first positive pressure generating grooves, the second positive pressure generating grooves may be provided in a smaller number than the first positive pressure generating grooves.

[0102] 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.

[0103] For example, in the above embodiment, 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.

[0104] In addition, in the above embodiment, a configuration has been exemplified in which the first positive pressure generating groove is provided in the stationary seal ring and the second positive pressure generating groove is provided in the rotary seal ring, but this is not limited to this, and the second positive pressure generating groove may be provided in the stationary seal ring and the first positive pressure generating groove may be provided in the rotary seal ring.

[0105] In the above embodiment, the first positive pressure generating groove and the second positive pressure generating groove extend obliquely in the circumferential direction from the leakage side toward the sealed fluid side, but the present invention is not limited to this and, for example, the first positive pressure generating groove or the second positive pressure generating groove may be formed with only a component extending in the circumferential direction. That is, it is sufficient that either the first positive pressure generating groove or the second positive pressure generating groove has a component extending in the radial direction and a component extending in the circumferential direction, and that the first positive pressure generating groove and the second positive pressure generating groove face each other so as to intersect at least partially.

[0106] Furthermore, in the above embodiment, 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 if the capacity of the first positive pressure generating groove is smaller than the capacity of the second positive pressure generating groove, for example, a step or an inclined surface may be formed on the bottom surface of the first positive pressure generating groove and the second positive pressure generating groove.

[0107] 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.

[0108] In addition, in the above embodiment, an inside type seal is used to seal the sealed fluid F that attempts to leak from the outer diameter side of the sliding surface toward the inner diameter side, but this is not limited to this, and an outside type seal may also be used to seal the sealed fluid F that attempts to leak from the inner diameter side of the sliding surface toward the outer diameter side.

[0109] In addition, in this embodiment, the sealed fluid F is described as a high-pressure liquid, but it is not limited to this and may be a gas or a low-pressure liquid, or may be a mist-like mixture of liquid and gas.

[0110] Furthermore, in this embodiment, the fluid on the leaking side is 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. [Explanation of symbols]

[0111] 10 Stationary seal ring (first sliding part) 11 Sliding surface 12 rand 14 First positive pressure generating groove 15 Intersection 20 Rotating seal ring (second sliding part) 21 Sliding surface 22 rand 24 Second positive pressure generating groove A. Atmosphere D1, D2 depth F Sealed fluid F1 1st force F2 2nd force S1 Internal space (leak side space) S2 outside space

Claims

1. A pair of sliding components that are arranged at relative rotational positions of a rotary machine and have sliding surfaces that slide relative to each other, a sliding surface of the first sliding element is provided with a plurality of first positive pressure generating grooves, each having an opening communicating with the leakage-side space and a closed terminal end located on the sealed fluid side, the first positive pressure generating grooves extending inclined toward the positive rotation side in the relative rotation direction when viewed from the opening to the terminal end; a sliding surface of the second sliding element is provided with a plurality of second positive pressure generating grooves, each having an opening communicating with the leakage side space and a closed terminal end located on the sealed fluid side, the second positive pressure generating grooves extending and inclined toward the positive rotation side in the relative rotation direction when viewed from the opening to the terminal end; The pair of sliding components are configured such that the sliding surface of the first sliding component and the sliding surface of the second sliding component cross and slide such that at least a portion of the first positive pressure generating groove and the second positive pressure generating groove overlap each other.

2. 2. A pair of sliding components according to claim 1, wherein a plurality of said second positive pressure generating grooves are arranged opposite to each of said first positive pressure generating grooves so as to intersect with each other.

3. 3. A pair of sliding components according to claim 1, wherein an end portion of the first positive pressure generating groove and an end portion of the second positive pressure generating groove are offset from each other in a radial direction.

4. 4. A pair of sliding components according to claim 1, wherein a volume of the first positive pressure generating groove is smaller than a volume of the second positive pressure generating groove.

5. 5. The pair of sliding components according to claim 4, wherein the first positive pressure generating groove has an extension distance shorter than that of the second positive pressure generating groove.

6. 6. A pair of sliding components according to claim 4, wherein the depth of the first positive pressure generating groove is shallower than the depth of the second positive pressure generating groove.

7. 7. A pair of sliding components according to claim 4, wherein the first positive pressure generating groove is inclined more inclined in the circumferential direction than the second positive pressure generating groove.

8. 8. A pair of sliding elements according to claim 4, wherein the width of the first positive pressure generating groove is smaller than the width of the second positive pressure generating groove.

9. 9. A pair of sliding components according to claim 2, wherein the first sliding component is a stationary seal ring and the second sliding component is a rotary seal ring.

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