Pair of sliding parts
The sliding parts with overlapping positive pressure grooves address the issue of insufficient dynamic pressure at low speeds, achieving effective wear suppression and leakage prevention through balanced pressure generation and contaminant discharge.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- EAGLE INDS
- Filing Date
- 2026-04-08
- Publication Date
- 2026-06-11
AI Technical Summary
Existing sliding parts in mechanical seals do not generate sufficient dynamic pressure at low speeds, leading to potential wear and leakage between sliding surfaces.
A pair of sliding parts with multiple first and second positive pressure generating grooves on each component, designed to overlap and intersect, allowing fluid to be drawn in at low speeds to generate separating forces and discharge contaminants, with varying groove volumes and orientations to manage wear and leakage across different rotation speeds.
The solution effectively suppresses wear and leakage between sliding surfaces from low to high rotation speeds by generating balanced positive pressure forces, ensuring efficient separation and containment of fluids.
Smart Images
Figure 2026095757000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to sliding parts that rotate relative to each other, and is used for a pair of sliding parts used for sealing the rotating shaft of a rotating machine in the field of automotive, general industrial machinery, or other sealing fields, such as a shaft sealing device, or a pair of sliding parts used for a bearing of a machine in the field of automotive, general industrial machinery, or other bearing fields.
Background Art
[0002] For example, a mechanical seal as a shaft sealing device for preventing leakage of a sealed fluid includes a pair of annular sliding parts that rotate relative to each other and whose sliding surfaces slide against each other. In such a mechanical seal, in recent years, reduction of energy lost due to sliding is desired for environmental protection and other reasons.
[0003] For example, the mechanical seal shown in Patent Document 1 is configured such that a pair of annular sliding parts can rotate relative to each other, a sealed fluid exists in the outer space, and a low-pressure fluid exists in the inner space. One of the sliding parts 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 whose ends are closed downstream in the relative rotation direction. According to this, when the pair of sliding parts rotate relative to each other, a low-pressure fluid is introduced into the spiral grooves of one of the sliding parts from the inner space, so that a positive pressure is generated at the ends and in the vicinity thereof, and the sliding surfaces of the pair of sliding parts are slightly separated from each other to achieve low friction.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, in the case of sliding parts such as those described in Patent Document 1, the spiral groove is provided on one of the sliding parts and extends from the inner diameter end to the outer diameter side, introducing low-pressure fluid into the internal space. Although this configuration allows for reduced wear, sufficient dynamic pressure is not generated in the spiral groove until the sliding parts reach a certain high-speed rotation state. This can cause delays in separating the sliding surfaces, potentially leading to wear between them.
[0006] This invention addresses these problems and aims to provide a pair of sliding parts that can suppress wear between sliding surfaces from the start of relative rotation to high-speed rotation, and that can suppress leakage of the sealed fluid. [Means for solving the problem]
[0007] To solve the aforementioned problems, the pair of sliding parts of the present invention are: A pair of sliding parts positioned at a point where they rotate relative to each other in a rotating machine, wherein the sliding surfaces of the sliding parts slide relative to each other. Multiple first positive pressure generating grooves are provided on the sliding surface of the first sliding component, communicating with the leakage side space and extending in the relative rotational direction of the second sliding component, with terminal ends. The sliding surface of the second sliding component is provided with a plurality of second positive pressure generating grooves that communicate with the leakage-side space, extend in the relative rotational direction of the first sliding component, and have an end portion. The sliding surface of the first sliding part and the sliding surface of the second sliding part are configured to slide across each other 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 at least one groove whose terminal position is different from that of the other grooves. The first groove has an end portion that is located on the sealed fluid space side than the end portions of the other grooves and the end portion of the second positive pressure generating groove. According to this, since the portions where the first positive pressure generating groove and the second positive pressure generating groove intersect are in communication, at low relative rotation speeds, fluid can be drawn in not only from the communication portion to the leakage side space of the first and second positive pressure generating grooves, but also from the opposing first or second positive pressure generating groove, instantly generating a force that separates the sliding surfaces. Furthermore, the first groove can discharge contaminants that have flowed into the sealed fluid space beyond the ends of the first and second positive pressure generating grooves towards the sealed fluid space from its end portion.
[0008] The end portion of the other groove may be located on the sealed fluid space side than the end portion of the second positive pressure generating groove. According to this, the positive pressure generated at the end of the other grooves and the positive pressure generated at the end of the second positive pressure generating groove do not interfere with each other.
[0009] The aforementioned groove may be provided in a rotating sealing ring, which is one of the pair of sliding parts. According to this, the first groove easily generates positive pressure by utilizing the rotational force of the rotating sealing ring. It also facilitates the discharge of contaminants.
[0010] The volume of the other groove may be greater than the volume of the second positive pressure generating groove, and the volume of the first groove may be greater than the volume of the other groove. According to this, at low relative rotation speeds of the sliding parts, the first force due to the positive pressure generated by the fluid in the second positive pressure generating groove becomes the main force that separates the sliding surfaces. Furthermore, as the relative rotation speed of the sliding parts increases, the second force due to the positive pressure generated by the fluid in other grooves increases, and when the relative rotation speed of the sliding parts becomes sufficiently high, the second force becomes greater than the first force, so the second force becomes the main force that separates the sliding surfaces, thereby suppressing wear between the sliding surfaces from low to high relative rotation speeds of the pair of sliding parts. Also, at high relative rotation speeds of the sliding parts, the gap formed between the sliding surfaces becomes larger, making it difficult for positive pressure to be generated in the second positive pressure generating groove, and the second force due to the positive pressure generated in other grooves becomes the main force that stably separates the sliding surfaces. Therefore, wear can be suppressed by separating the sliding surfaces from the start of relative rotation of the pair of sliding parts to high-speed rotation.
[0011] The aforementioned groove may be equally spaced in the circumferential direction. According to this, the positive pressure in the first groove is generated in a balanced manner in the circumferential direction of the sliding surface, and therefore does not affect the separation between the sliding surfaces. [Brief explanation of the drawing]
[0012] [Figure 1] This is a longitudinal cross-sectional view showing an example of a mechanical seal in Embodiment 1 of the present invention. [Figure 2] This is a view of the sliding surface of the stationary sealing ring, seen from the axial direction. [Figure 3] This is a view of the sliding surface of the rotating sealing ring, seen from the axial direction. [Figure 4] This is a schematic diagram illustrating the arrangement of the sliding surfaces of the stationary sealing ring and the rotating sealing ring facing each other. The second positive pressure generating groove of the rotating sealing ring is indicated by a dashed line. [Figure 5] (a) is a schematic cross-sectional view showing the other grooves of the first positive pressure generating groove and the second positive pressure generating groove, and (b) is a schematic cross-sectional view showing one groove of the first positive pressure generating groove and the second positive pressure generating groove. [Figure 6](a) is an explanatory view of the fluid movement in one groove and the other groove of the first positive pressure generating groove as seen from the axial direction, and (b) is an explanatory view of the fluid movement in the second positive pressure generating groove as seen from the axial direction. [Figure 7] (a) to (c) are cross-sectional views schematically showing the states for each relative rotational speed of a pair of sliding parts. [Figure 8] It is an explanatory view showing the positional change of the intersection of the first positive pressure generating groove and the second positive pressure generating groove. Note that the intersection of one first positive pressure generating groove and one second positive pressure generating groove is taken up and illustrated. [Figure 9] It is a cross-sectional view schematically showing the other groove of the first positive pressure generating groove and the second positive pressure generating groove in Example 2 of the present invention. [Figure 10] It is a view of the sliding surface of the stationary seal ring in Example 3 of the present invention as seen from the axial direction. [Figure 11] It is a view of the sliding surface of the stationary seal ring in Example 4 of the present invention as seen from the axial direction. [Figure 12] It is a view of the sliding surface of the stationary seal ring in Example 5 of the present invention as seen from the axial direction. [Figure 13] It is a view of the sliding surface of the rotating seal ring of Modification 1 as seen from the axial direction. [Figure 14] It is a view of the sliding surface of the stationary seal ring of Modification 2 as seen from the axial direction. [Figure 15] It is a view of the sliding surface of the stationary seal ring of Modification 3 as seen from the axial direction. [Figure 16] It is a view of the sliding surface of the rotating seal ring of Modification 3 as seen from the axial direction.
Embodiments for Carrying Out the Invention
[0013] The embodiments for carrying out a pair of sliding parts according to the present invention will be described below based on examples.
Examples
[0014] A pair of sliding parts according to Example 1 will be described with reference to Figures 1 to 8. In this example, the sliding parts are described as a mechanical seal. Furthermore, the sealed fluid is present in the outer space of the mechanical seal, and the atmosphere is present in the inner space. The outer diameter side of the sliding parts 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). Also, for the sake of explanation, dots may be added to grooves and the like formed on the sliding surface in the drawings.
[0015] The mechanical seal for general industrial machinery shown in Figure 1 is an inside-type seal that seals the fluid F to be sealed, which tends to leak from the outer diameter side to the inner diameter side of the sliding surface, and the inner space S1, which serves as the leakage space, is open to the atmosphere A. In this embodiment, the example shown is one in which the fluid to be sealed F is a high-pressure liquid and the atmosphere A is a gas at a lower pressure than the fluid to be sealed F.
[0016] The mechanical seal mainly consists of an annular rotating sealing ring 20 as a second sliding component and an annular stationary sealing ring 10 as a first sliding component. The rotating sealing ring 20 is attached to a sleeve 2 fixed to a rotating shaft 1 and is rotatable with the rotating shaft 1. The stationary sealing ring 10 is fixed to a seal cover 5 fixed to the housing 4 of the equipment to be mounted in a non-rotatable and axially movable state.
[0017] The stationary sealing ring 10 is biased axially by the bellows 7. As a result, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 slide in close contact with each other.
[0018] The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed from two SiC (hard material) components or a combination of SiC (hard material) and carbon (soft material), but are not limited to these; any sliding material used for mechanical seals is applicable. SiC can be sintered using boron, aluminum, carbon, etc., as sintering aids, or from materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC made of SiC and Si, SiC-TiC, SiC-TiN, etc. Carbon can be a mixture of carbonaceous and graphite, as well as resin-molded carbon and sintered carbon. In addition to the sliding materials mentioned above, metal materials, resin materials, surface modification materials (coating materials), and composite materials are also applicable.
[0019] The sliding surface 11 of the stationary sealing ring 10 is provided with multiple first positive pressure generating grooves 14 (as other grooves) and multiple first positive pressure generating grooves 15 (as single grooves). The first positive pressure generating grooves 14 and 15 have different lengths.
[0020] The first positive pressure generating groove 14 has an inner diameter end, i.e., a relative rotation starting end 14A, that communicates with the inner space S1, and extends in an arc shape from the starting end 14A toward the outer diameter, inclined downstream in the rotational direction of the rotating sealing ring 20. The outer diameter end of the first positive pressure generating groove 14, i.e., the relative rotation end 14B which serves as the terminal end, is closed so as not to communicate with the outer space S2 which serves as the sealed fluid space. This first positive pressure generating groove 14 has an arc shape that is convex toward the outer diameter.
[0021] In detail, 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 and extends parallel to the flat surface of the land 12 from the starting end 14A to the ending end 14B. The wall portion 14b extends perpendicularly from the end edge 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 sides of the bottom surface 14a toward the flat surface of the land 12. The angle between the wall portion 14b and the side wall portion 14c is obtuse, and the angle between the wall portion 14b and the side wall portion 14d is acute. The acute angle portion 14f of the wall portion 14b on the side wall portion 14d side is located downstream in the rotational direction of the rotating sealing ring 20 than the obtuse angle portion 14e of the wall portion 14b on the side wall portion 14c side.
[0022] The first positive pressure generating groove 15 has an inner diameter 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, inclined downstream in the rotational direction of the rotating sealing ring 20. The outer diameter end of the first positive pressure generating groove 15, i.e., the relative rotation end 15B which serves as the end portion, 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. Furthermore, as will be described in more detail later, this first positive pressure generating groove 15 has a longer extension distance than the first positive pressure generating groove 14.
[0023] In detail, 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 and extends parallel to the flat surface of the land 12 from the starting end 15A to the ending end 15B. The wall portion 15b extends perpendicularly from the end edge 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 sides of the bottom surface 15a toward the flat surface of the land 12. The angle between the wall portion 15b and the side wall portion 15c is obtuse, and the angle between the wall portion 15b and the side wall portion 15d is acute. The acute angle portion 15f of the wall portion 15b on the side wall portion 15d side is located downstream in the rotational direction of the rotating sealing ring 20 than the obtuse angle portion 15e of the wall portion 15b on the side wall portion 15c side.
[0024] These first positive pressure generating grooves 15 are equally spaced in the circumferential direction of the sliding surface 11. In addition, multiple (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.
[0025] The first positive pressure generating grooves 14 and 15 are arranged such that, when viewed from the axial direction, multiple grooves overlap radially. In other words, two first positive pressure generating grooves 14 and one first positive pressure generating groove 15 are arranged along the radial line.
[0026] As shown in Figure 3, the sliding surface 21 of the rotating sealing ring 20 has multiple (24 in Example 1) second positive pressure generating grooves 24 evenly arranged in the circumferential direction on the inner diameter side. The portion of the sliding surface 21 other than the second positive pressure generating grooves 24 is a flat land 22. Furthermore, the rotating sealing ring 20 rotates clockwise as indicated by the arrow when viewed axially from the sliding surface 21.
[0027] The second positive pressure generating groove 24 has an inner diameter end, i.e., a relative rotation starting end 24A, that communicates with the inner space S1, and extends in an arc shape from the starting end 24A toward the outer diameter, inclined toward the upstream side in the rotational direction of the rotating sealing ring 20, while its outer diameter end, i.e., the relative rotation end 24B which serves as the end portion, 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.
[0028] In detail, the second positive pressure generating groove 24 is composed of a bottom surface 24a that is flat and parallel to the flat surface of the land 22 from the starting end 24A to the ending end 24B, a wall portion 24b that extends perpendicularly from the end edge 24B of the bottom surface 24a toward the flat surface of the land 22, and side wall portions 24c and 24d that extend perpendicularly from both side edges of the bottom surface 24a toward the flat surface of the land 22. The angle between the wall portion 24b and the side wall portion 24c is obtuse, and the angle between the wall portion 24b and the side wall portion 24d is acute, with the acute angle portion 24f of the wall portion 24b on the side wall portion 24d side being located downstream in the rotational direction of the rotating sealing ring 20 than the obtuse angle portion 24e of the wall portion 24b on the side wall portion 24c side.
[0029] The second positive pressure generating grooves 24 are arranged such that, when viewed from the axial direction, multiple grooves (three in Example 1) overlap radially. In other words, multiple grooves (three in Example 1) of the second positive pressure generating grooves 24 are arranged along the radial line.
[0030] As shown in Figure 4, when the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 are facing each other, the first positive pressure generating groove 14 and the first positive pressure generating groove 15 and the second positive pressure generating groove 24 are arranged to intersect when viewed from the axial direction. In Figure 4, the sliding surface 11 of the stationary sealing ring 10 is shown as viewed from the axial direction, with the first positive pressure generating groove 14 and the first positive pressure generating groove 15 shown as solid lines, and the opposing second positive pressure generating groove 24 shown as a dashed line.
[0031] Specifically, multiple first positive pressure generating grooves 14 and 15 are arranged opposite and intersecting a single second positive pressure generating groove 24. That is, multiple intersections 16 are formed between the first positive pressure generating grooves 14 and 15 and the second positive pressure generating groove 24 between the sliding surface 11 and the sliding surface 21.
[0032] Furthermore, as shown in Figures 4 and 5(a), 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).
[0033] Figure 5 is a schematic cross-sectional view, for the sake of explanation, showing the longitudinal sections of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24, each arranged at the same position in the axial direction.
[0034] Furthermore, the first positive pressure generating groove 14 has a constant depth D1 along its extending direction. The second positive pressure generating groove 24 also has a constant depth D2 along its extending 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).
[0035] Furthermore, as shown in Figures 4 and 5(b), 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).
[0036] Specifically, the extended length L10 of the first positive pressure generating groove 14 and the extended length L20 of the second positive pressure generating groove 24 are approximately 3 / 4 of the extended length L11 of the first positive pressure generating groove 15.
[0037] The end 15B of the first positive pressure generating groove 15 is located on the outer diameter side of the end 14B of the first positive pressure generating groove 14 and the end 24B of the second positive pressure generating groove 24.
[0038] Furthermore, the first positive pressure generating groove 15 has a constant depth D3 along its extending direction. The depth D3 of the first positive pressure generating groove 15 is the same dimension 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 depth as the depth D2 of the second positive pressure generating groove 24 (D3=D2).
[0039] Furthermore, the width dimensions of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 are approximately the same. In addition, since 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, the area of the first positive pressure generating groove 15 as viewed from the axial direction is larger than the area of the first positive pressure generating groove 14 and the area of the second positive pressure generating groove 24. Moreover, the area of the first positive pressure generating groove 14 as viewed from the axial direction is larger than the area of the second positive pressure generating groove 24.
[0040] 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 determined by multiplying the respective areas 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 from 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 from the axial direction is larger than the area of the first positive pressure generating groove 14, and the area of the first positive pressure generating groove 14 is larger than the area of the second positive pressure generating groove 24. Also, 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, and the volume of the first positive pressure generating groove 14 is larger than the volume of the second positive pressure generating groove 24.
[0041] Next, the flow of atmospheric A during the relative rotation of the stationary sealing ring 10 and the rotating sealing ring 20 will be schematically explained using Figure 6. Note that the flow of atmospheric A in Figure 6 is shown schematically without specifying the relative rotation speed of the rotating sealing ring 20.
[0042] First, let's explain the flow of atmospheric air A within the first positive pressure generating groove 14. As shown in Figure 6(a), when the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the atmospheric air A within the first positive pressure generating groove 14 moves from the starting end 14A to the ending end 14B, as indicated by the white arrow L1.
[0043] As the air A moves toward the terminal 14B, its pressure increases at the acute angle 14f of the wall portion 14b of the first positive pressure generating groove 14 and in its vicinity, and it flows out between the sliding surfaces 11 and 21 as shown by the white arrow L2. In other words, positive pressure is generated at the acute angle 14f and in its vicinity.
[0044] The air 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 towards the outer space S2, so that the sealed fluid F does not leak into the inner space S1.
[0045] Next, the flow of air A within the first positive pressure generating groove 15 will be described. When the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the air A within the first positive pressure generating groove 15 moves from the starting end 15A to the ending end 15B, as indicated by the white arrow L3.
[0046] As atmospheric air A moves toward the terminal 15B, its pressure increases at the acute angle 15f of the wall portion 15b of the first positive pressure generating groove 15 and in its vicinity, and it flows out between the sliding surfaces 11 and 21 as shown by the white arrow L4. In other words, positive pressure is generated at the acute angle 15f and in its vicinity.
[0047] The air A in the first positive pressure generating groove 15, indicated by the white arrow L4, acts to push the sealed fluid F near the end 15B of the first positive pressure generating groove 15 back towards the outer space S2, so that the sealed fluid F does not leak into the inner space S1.
[0048] Next, the flow of atmospheric air A within the second positive pressure generating groove 24 will be explained. As shown in Figure 6(b), when the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the atmospheric air A within the second positive pressure generating groove 24 moves from the starting end 24A to the ending end 24B, as indicated by the white arrow L5.
[0049] As the air A moves toward the terminal 24B, its pressure increases at the acute angle 24f of the wall portion 24b of the second positive pressure generating groove 24 and in its vicinity, and it flows out between the sliding surfaces 11 and 21 as shown by the white arrow L6. In other words, positive pressure is generated at the acute angle 24f and in its vicinity.
[0050] The air 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 towards the outer space S2, so that the sealed fluid F does not leak into the inner space S1.
[0051] Next, the change in the force that separates the sliding surfaces 11 and 21 will be explained using Figure 7. Note that here, the forces generated in the first positive pressure generating groove 14 and the second positive pressure generating groove 24 are illustrated, while the force generated in the first positive pressure generating groove 15 is omitted.
[0052] First, when the rotating sealing ring 20 is not rotating, the stationary sealing ring 10 is biased toward the rotating sealing ring 20 by the bellows 7, so the sliding surfaces 11 and 21 are in contact with each other, and there is almost no leakage of the sealed fluid F between the sliding surfaces 11 and 21 into the internal space S1.
[0053] At low speeds immediately after the rotating sealing ring 20 begins to rotate relative to the stationary sealing ring 10, 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 smaller capacity than the first positive pressure generating groove 14.
[0054] The first force F1 caused by the positive pressure generated at the end 24B of the second positive pressure generating groove 24 causes the sliding surfaces 11 and 21 to separate slightly by a distance Δa. As a result, the sealed fluid F flows from the outer space S2 into 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 rotational speeds and suppresses wear between the sliding surfaces 11 and 21. Furthermore, because the floating distance between the sliding surfaces 11 and 21 is small, the sealed fluid F does not leak into the inner space S1.
[0055] On the other hand, since the capacity of the first positive pressure generating groove 14 is larger than that of the second positive pressure generating groove 24, when the relative rotation speed of the rotating sealing ring 20 and the stationary sealing ring 10 is low, the atmosphere A does not become sufficiently dense in the first positive pressure generating groove 14, and high positive pressure is not generated. As a result, the second force F2 (not shown in Figure 7(a)) due to the positive pressure generated by the first positive pressure generating groove 14 is relatively smaller than the first force F1. Therefore, when the rotating sealing ring 20 is rotating at low speed, the first force F1 is the main force that separates the sliding surfaces 11 and 21. Furthermore, since the capacity of the first positive pressure generating groove 15 is larger than that of the second positive pressure generating groove 24, the force due to the positive pressure generated by the first positive pressure generating groove 15 is relatively smaller than the first force F1 when the relative rotation speed is low.
[0056] As the relative rotational speed of the rotating sealing ring 20 increases, the positive pressure increases at the end 14B of the first positive pressure generating groove 14, as shown in Figure 7(b). At this time, although not shown, the positive pressure also increases at the end 15B of the first positive pressure generating groove 15.
[0057] A second force F2 is added, which is the sum of the positive pressure force generated at the end 14B of the first positive pressure generating groove 14 and the positive pressure force at the end 15B of the first positive pressure generating groove 15. Compared to Figure 7(a), the distance between the sliding surfaces 11 and 21 increases by a further distance Δb (Δb > Δa). As a result, air A from within the first positive pressure generating groove 14 flows into the space between the sliding surfaces 11 and 21, mainly as indicated by the white arrow L2.
[0058] Furthermore, compared to Figure 7(a), the gap between the sliding surfaces 11 and 21 widens further by Δb (Δb > Δa), resulting in a smaller first force F1' compared to Figure 7(a).
[0059] As the relative rotational speed of the rotating sealing ring 20 increases further and reaches high-speed rotation, i.e., a steady-state operation, as shown in Figure 7(c), the amount of atmospheric A drawn into the first positive pressure generating groove 14 (see white arrow L1' in Figure 7(c)) and the amount of atmospheric A drawn into the first positive pressure generating groove 15 increase further, generating a high positive pressure, increasing the second force F2', and causing the sliding surfaces 11 and 21 to separate more widely Δc (Δc>Δb) compared to Figure 7(b).
[0060] As a result, compared to Figure 7(b), more air A from the first positive pressure generating groove 14 and air A from the first positive pressure generating groove 15 flows into the space between the sliding surfaces 11 and 21, indicated by the white arrow L2'.
[0061] The air A in the first positive pressure generating groove 14 and the air A in the first positive pressure generating groove 15, indicated by the white arrow L2', act to push 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 Figure 6(a)) back towards the outer space S2. In this way, during high-speed rotation, the sealed fluid F between the sliding surfaces 11 and 21 is pushed out into the outer space S2, and almost only air A remains between the sliding surfaces 11 and 21.
[0062] In this embodiment, as the levitation distance increases due to the high-speed rotation of the rotating sealing ring 20, the positive pressure generated in the second positive pressure generating groove 24 becomes negligibly small. Therefore, when the rotating sealing ring 20 is rotating at high speed, the second force F2' becomes the main force that separates the sliding surfaces 11 and 21 from each other.
[0063] Returning to Figure 4, the sliding surfaces 11 and 21 have multiple intersections 16 between the first positive pressure generating groove 14 and the second positive pressure generating groove 24, and between the first positive pressure generating groove 15 and the second positive pressure generating groove 24. As a result, in addition to air A being introduced into the second positive pressure generating groove 24 from the starting end 24A side, air A is also introduced from the first positive pressure generating groove 14 through the intersections 16, so that the first force F1 (see Figure 7) that separates the sliding surfaces 11 and 21 can be generated early.
[0064] Next, the change in the intersection position of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 during relative rotation between the stationary sealing ring 10 and the rotating sealing ring 20 will be explained using Figure 8. For the sake of explanation, 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 explained, and the intersection 16 will be illustrated with halftone dots.
[0065] Figure 8(a) shows the state where the starting end 14A of the first positive pressure generating groove 14 and the starting end 24A of the second positive pressure generating groove 24 intersect when viewed from the axial direction. That is, the intersection 16 with the second positive pressure generating groove 24 is located at the starting end 14A of the first positive pressure generating groove 14.
[0066] When the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the intersection 16 moves toward the end 14B of the first positive pressure generating groove 14, as shown in Figure 8(b), and is positioned in the longitudinal center of the first positive pressure generating groove 14.
[0067] 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 at the intersection 16 is higher than in the parts of the first positive pressure generating groove 14 and the second positive pressure generating groove 24 other than the intersection 16.
[0068] Furthermore, as the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, the intersection 16 moves further toward the end 14B of the first positive pressure generating groove 14, as shown in Figure 8(c).
[0069] At this time, the mass of fluid collected in the intersection 16 is subjected to shear force between the side wall 14d of the first positive pressure generating groove 14 and the acute angle 24f of the second positive pressure generating groove 24, causing a large positive pressure to be generated.
[0070] In this way, the fluid mass 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. As a result, the first force F1 (see Figure 7) that separates the sliding surfaces 11, 21 can be generated early.
[0071] Furthermore, when the rotating sealing ring 20 rotates relative to the stationary sealing ring 10, fluid from the first positive pressure generating groove 15 can be drawn 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, thereby enabling positive pressure to be generated in the second positive pressure generating groove 24 at an early stage.
[0072] Next, the contaminant C that flowed between the sliding surfaces 11 and 21 will be explained with reference to Figure 6.
[0073] The sealed fluid F flowing between the sliding surfaces 11 and 21 may contain contaminants. These contaminants are mainly located in the lands 12 and 22 on the outer diameter side 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 rotational direction of the rotating sealing ring 20 and are collected in the portion of the first positive pressure generating groove 15 located on the outer diameter side of the first positive pressure generating groove 14 and the second positive pressure generating groove 24.
[0074] The contaminants collected in the first positive pressure generating groove 15 move toward the end 15B together with the air A, indicated by the white arrow L3, flowing through the groove 15, as shown by the black arrow C2 in Figure 6(a). The contaminants are then discharged outwards from the acute angle 15f of the first positive pressure generating groove 15 and its vicinity, and most of them are discharged into the outer space S2, as shown by the black arrow C3 in Figure 6(a). This prevents contaminants from remaining between the sliding surfaces 11 and 21 for extended periods.
[0075] As explained above, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 slide against each other when the first positive pressure generating groove 14 and the first positive pressure generating groove 15 intersect with the second positive pressure generating groove 24. The intersection 16 of the first positive pressure generating groove 14 and the second positive pressure generating groove 24, and the intersection 16 of the first positive pressure generating groove 15 and the second positive pressure generating groove 24 are in communication. Therefore, at low relative rotation 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, thereby immediately generating the first force F1.
[0076] Furthermore, multiple first positive pressure generating grooves 14 intersect and face each other in one second positive pressure generating groove 24. When the stationary sealing ring 10 and the rotating sealing ring 20 rotate relative to each other, fluid can be drawn into each second positive pressure generating groove 24 from multiple first positive pressure generating grooves 14, thereby enabling positive pressure to be generated in the second positive pressure generating groove 24 at an early stage.
[0077] Furthermore, the first positive pressure generating groove 15 can collect contaminants that have flowed into the outer space S2 side beyond the end 14B of the first positive pressure generating groove 14 and the end 24B of the second positive pressure generating groove 24 between the sliding surfaces 11 and 21, and discharge them into the outer space S2 from its end 15B. By changing the length of the first positive pressure generating groove 15, the effect of discharging contaminants can be enhanced.
[0078] Furthermore, the first positive pressure generating groove 15 is a positive pressure generating groove that generates positive pressure. As a result, the positive pressure generated in the first positive pressure generating groove 15 can discharge contaminant C from the first positive pressure generating groove 15 and can also be used as a force to separate the sliding surfaces 11 and 21 from each other.
[0079] Furthermore, the first positive pressure generating groove 15 is provided in the stationary sealing ring 10. As a result, when the relative rotation speed between the stationary sealing ring 10 and the rotating sealing ring 20 is low, fluid is less likely to be introduced into the first positive pressure generating groove 15 on the stationary sealing ring 10 side compared to the second positive pressure generating groove 24 on the rotating sealing ring 20 side. Therefore, fluid flow is less likely to occur within the first positive pressure generating groove 15, and the generation of positive pressure in the second positive pressure generating groove 24 is not hindered. In other words, the second positive pressure generating groove 24 can generate positive pressure when the relative rotation speed between the stationary sealing ring 10 and the rotating sealing ring 20 is low.
[0080] 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 rotation speed of the stationary sealing ring 10 and the rotating sealing ring 20 is low, the first force F1 caused by the positive pressure generated by the atmosphere A in the second positive pressure generating groove 24 is the main force that separates the sliding surfaces 11 and 21. As the relative rotation speed of the stationary sealing ring 10 and the rotating sealing ring 20 increases, the second force F2 caused by the positive pressure generated by the atmosphere A in the first positive pressure generating groove 14 increases, and when the relative rotation speed of the stationary sealing ring 10 and the rotating sealing ring 20 becomes sufficiently high, the second force F2 becomes larger than the first force F1, so the second force F2 becomes the main force that separates the sliding surfaces 11 and 21. This makes it possible to suppress wear between the sliding surfaces 11 and 21 from low to high relative rotation speeds of the stationary sealing ring 10 and the rotating sealing ring 20.
[0081] Furthermore, the volume of the first positive pressure generating groove 15 is larger than the volume of the first positive pressure generating groove 14. As a result, when the relative rotation speed of the stationary sealing ring 10 and the rotating sealing ring 20 is high, a greater positive pressure can be generated than that of the first positive pressure generating groove 14 and the second positive pressure generating groove 24, making it easier to discharge contaminants C into the outer space S2.
[0082] Furthermore, since the number of first positive pressure generating grooves 15 is less than that of the first positive pressure generating grooves 14, it does not hinder the separation of the sliding surfaces 11 and 21, which are mainly affected by the second force F2'.
[0083] Furthermore, since the first positive pressure generating grooves 15 are equally spaced 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 and 21, and does not hinder the separation of the sliding surfaces 11 and 21.
[0084] Furthermore, the second positive pressure generating groove 24, which has a smaller capacity than the first positive pressure generating groove 14, is provided on the rotating sealing ring 20. As a result, fluid can be easily introduced into the second positive pressure generating groove 24 by the rotational force of the rotating sealing ring 20. Therefore, when the relative rotation speed between the stationary sealing ring 10 and the rotating sealing ring 20 is low, positive pressure can be immediately generated in the second positive pressure generating groove 24, which has a smaller volume, by the rotation of the rotating sealing ring 20.
[0085] Furthermore, the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 extend in a circumferential inclination from the inner space S1 side toward the outer diameter side. This allows for a large number of the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24 to be placed on the respective sliding surfaces 11 and 21 of the stationary sealing ring 10 and the rotating sealing ring 20, thus providing a high degree of design flexibility.
[0086] Furthermore, since the end 14B of the first positive pressure generating groove 14 is located on the outer diameter side than the end 24B of the second positive pressure generating groove 24, the positive pressure generated at end 14B and the positive pressure generated at end 24B do not interfere with each other. [Examples]
[0087] Next, a pair of sliding parts according to Embodiment 2 will be described with reference to Figure 9. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.
[0088] As shown in Figure 9, the extension length L10' of the first positive pressure generating groove 140 of the stationary sealing ring 100 is the same length as the extension length L20 of the second positive pressure generating groove 24. Although not shown, the extension length L10' of the first positive pressure generating groove 140 is shorter than the extension length L11 of the first positive pressure generating groove 15.
[0089] Furthermore, the depth D1' of the first positive pressure generating groove 140 is greater than the depth D2 of the second positive pressure generating groove 24. That is, the volume of the first positive pressure generating groove 140 is greater than the volume of the second positive pressure generating groove 24. Although not shown in the diagram, the depth of the first positive pressure generating groove 15 is the same as the depth D1' of the first positive pressure generating groove 140. That is, the volume of the first positive pressure generating groove 15 is greater than the volumes of both the first positive pressure generating groove 140 and the second positive pressure generating groove 24. [Examples]
[0090] Next, a pair of sliding parts according to Embodiment 3 will be described with reference to Figure 10. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.
[0091] As shown in Figure 10, the sliding surface 111 of the stationary sealing ring 101 has first positive pressure generating grooves 141 and first positive pressure generating grooves 151 arranged alternately in the circumferential direction.
[0092] According to this, contaminants present on the outer diameter side of the first positive pressure generating groove 141 on the sliding surface 111 are discharged into the outer space S2 by the first positive pressure generating groove 151 adjacent to the downstream side in the relative rotational direction of the rotating sealing ring 20. [Examples]
[0093] Next, a pair of sliding parts according to Embodiment 4 will be described with reference to Figure 11. Note that descriptions of components identical to those in Embodiment 1 and therefore redundant will be omitted.
[0094] As shown in Figure 11, the sliding surface 112 of the stationary sealing ring 102 has first positive pressure generating grooves 152 evenly spaced in the circumferential direction (six in this embodiment). In addition, first positive pressure generating grooves 142a, 142b, and 142c are arranged between adjacent first positive pressure generating grooves 152 in the circumferential direction.
[0095] The first positive pressure generating groove 142a is located upstream of the first positive pressure generating grooves 142b and 142c in the relative rotational direction of the rotating sealing ring 20, the first positive pressure generating groove 142c is located downstream of the first positive pressure generating grooves 142a and 142b in the relative rotational direction of the rotating sealing ring 20, and the first positive pressure generating groove 142b is located between the first positive pressure generating grooves 142a and 142c.
[0096] The first positive pressure generating grooves 142a, 142b, and 142c are shorter than the first positive pressure generating groove 152. Also, the first positive pressure generating grooves 142a and 142c are the same length. Furthermore, the first positive pressure generating groove 142b is shorter than the first positive pressure generating grooves 142a and 142c.
[0097] Contaminants present on the outer diameter side of the first positive pressure generating groove 142b are collected in the first positive pressure generating groove 142c, then discharged toward the first positive pressure generating groove 152 on the downstream side of relative rotation, and discharged from the first positive pressure generating groove 152 into the outer space S2. In this way, contaminants on the inner diameter side of the sliding surface 112, i.e., at a position away from the outer space S2, are discharged into the outer space S2 through the first positive pressure generating groove 142a and the first positive pressure generating groove 152.
[0098] Furthermore, a first positive pressure generating groove 142a, which is the same length as the first positive pressure generating groove 142c, is provided on the relative rotation upstream side of the first positive pressure generating groove 142b. As a result, the ends of the first positive pressure generating grooves 142a, 142b, and 142c, and the end of the first positive pressure generating groove 152, are arranged in a balanced manner across the circumferential and radial directions of the sliding surface 112, thereby allowing the sliding surfaces to be spaced apart in a balanced manner.
[0099] In this embodiment 4, the stationary sealing ring 102 has first positive pressure generating grooves 142a, 142b, 142c and a first positive pressure generating groove 152, which are of different lengths. In this case, the first positive pressure generating groove 152, which has the longest extension distance, functions as one groove, and the other first positive pressure generating grooves 142a, 142b, and 142c, which are shorter than the first positive pressure generating groove 152, function as other grooves. [Examples]
[0100] Next, a pair of sliding parts according to Example 5 will be described with reference to Figure 12. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.
[0101] As shown in Figure 12, the sliding surface 113 of the stationary sealing ring 103 is provided with multiple (three in this embodiment) dynamic pressure generating mechanisms 17 in addition to the first positive pressure generating groove 14 and the first positive pressure generating groove 15.
[0102] The dynamic pressure generating mechanism 17 consists of a fluid introduction groove 17a and a Rayleigh step 17b. The fluid introduction groove 17a extends radially, communicating 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 introduction groove 17a, counterclockwise in the plane of the paper in Figure 12, that is, in the relative rotation direction of the rotating sealing ring 20, concentrically with the stationary sealing ring 103.
[0103] According to this, in addition to reducing friction between sliding surfaces using air A through the first positive pressure generating groove 14, the first positive pressure generating groove 15, and the second positive pressure generating groove 24, liquid lubrication using the sealed fluid F by the dynamic pressure generating mechanism 17 can be performed.
[0104] In the above embodiments 1 to 5, the sliding surface of the rotating sealing ring was shown to be provided with second positive pressure generating grooves of the same length. However, as shown in Figure 13, for example, the sliding surface of the rotating sealing ring 200 may be provided with second positive pressure generating grooves 240a and 240b of different lengths.
[0105] Furthermore, in the above embodiments 1 to 5, the leak side was described as the inner space and the sealed fluid side as the outer space. However, for example, as shown in Figure 14, the sealed fluid F may be enclosed in the inner space S1, and the atmosphere A may be present in the outer space S2. In this case, the first positive pressure generating groove 143 and the first positive pressure generating groove 153 should communicate with the outer space S2 but not with the inner space S1. In addition, although not shown, the second positive pressure generating groove should also communicate with the outer space S2 but not with the inner space S1.
[0106] Furthermore, in the above embodiments 1 to 5, the stationary sealing ring was exemplified as the first sliding part and the rotating sealing ring as the second sliding part. However, for example, as shown in Figures 15 and 16, the stationary sealing ring 300 may be the second sliding part and the rotating sealing ring 400 may be the first sliding part.
[0107] Specifically, as shown in Figure 15, multiple second positive pressure generating grooves 302 of the same length are formed circumferentially on the sliding surface 301 of the stationary sealing ring 300. Also, as shown in Figure 16, multiple first positive pressure generating grooves 402 (as other grooves) and multiple first positive pressure generating grooves 403 (as a single groove) are provided on the sliding surface 401 of the rotating sealing ring 400.
[0108] As described above, since the first positive pressure generating groove 403 is provided in the rotating sealing ring 400, positive pressure is easily generated in the first positive pressure generating groove 403 by utilizing the rotational force of the rotating sealing ring 400, and contaminants are easily discharged.
[0109] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.
[0110] For example, in the above embodiments 1 to 5, mechanical seals for general industrial machinery were described as sliding parts, but other mechanical seals such as those for automobiles or water pumps may also be used. Furthermore, the invention is not limited to mechanical seals, but may also use sliding parts other than mechanical seals, such as sliding bearings.
[0111] Furthermore, while embodiments 1 to 5 above illustrate configurations in which the other grooves are longer than or equal to the length of the second positive pressure generating groove, the invention is not limited to this configuration. As long as one groove is longer than the second positive pressure generating groove, the other grooves may be shorter than the second positive pressure generating groove.
[0112] Furthermore, while embodiments 1 to 5 illustrate a configuration in which the positive pressure generated in one groove of the first positive pressure generating groove is greater than the positive pressure generated in the other grooves of the first positive pressure generating groove and the positive pressure generated in the second positive pressure generating groove, the positive pressure generated in one groove may be smaller than the positive pressure generated in the other grooves and the second positive pressure generating groove. In this case, the other grooves may play a more primary role in separating the sliding surfaces.
[0113] Furthermore, while embodiments 1 to 5 illustrate a configuration in which the degree of inclination in the circumferential direction between the first positive pressure generating groove and the second positive pressure generating groove as viewed from each sliding surface is approximately the same, the degree of inclination in the circumferential direction may be different.
[0114] Furthermore, while embodiments 1 to 5 above illustrate a configuration in which multiple first positive pressure generating grooves intersect and face one second positive pressure generating groove, it is also possible for one first positive pressure generating groove to intersect and face one second positive pressure generating groove.
[0115] Furthermore, while embodiments 1 to 5 above illustrate a configuration in which the volume of the other grooves in the first positive pressure generating groove is larger than the volume of the second positive pressure generating groove, the volume of the other grooves in the first positive pressure generating groove may be smaller than the volume of the second positive pressure generating groove, or the volume of the other grooves in the first positive pressure generating groove may be the same as the volume of the second positive pressure generating groove.
[0116] Furthermore, in Embodiment 1, the length of the first positive pressure generating groove is formed to be longer than the length of the second positive pressure generating groove, and in Embodiment 2, the depth of the first positive pressure generating groove is formed to be deeper than the depth of the second positive pressure generating groove, thereby illustrating a configuration in which the volume of the first positive pressure generating groove is larger than the volume of the second positive pressure generating groove. However, the width of the first positive pressure generating groove may be formed to be larger than the width of the second positive pressure generating groove, thereby resulting in a volume of the first positive pressure generating groove being larger than the volume of the second positive pressure generating groove.
[0117] Furthermore, while embodiments 1 to 5 illustrate a configuration in which one groove of the first positive pressure generating groove, the other groove, and the second positive pressure generating groove extend in a circumferential inclination from the leak side toward the sealed fluid side, the embodiment is not limited to this. For example, one groove of the first positive pressure generating groove, the other groove, or the second positive pressure generating groove may be formed only from a component that extends in the circumferential direction. That is, it is sufficient that one of the one groove of the first positive pressure generating groove, the other groove, or the second positive pressure generating groove has a component that extends in the radial direction and a component that extends in the circumferential direction, and that one groove of the first positive pressure generating groove, the other groove, and the second positive pressure generating groove face each other so as to intersect in at least a part.
[0118] Furthermore, while embodiments 1 to 5 above illustrate a configuration in which one groove is equally spaced in the circumferential direction, it is not necessary for them to be equally spaced. Also, it is sufficient that at least one groove is provided.
[0119] Furthermore, while the above-described examples 1 to 5 illustrate a configuration in which the number of grooves in one groove is less than the number of other grooves, the number of grooves in one groove may be the same as or greater than the number of other grooves.
[0120] Furthermore, while embodiments 1 to 5 above illustrate a configuration in which the cross-sectional shapes of one groove, the other groove, and the second positive pressure generating groove of the first positive pressure generating groove are constant in the longitudinal direction, for example, steps or inclined surfaces may be formed on the bottom surfaces of one groove, the other groove, and the second positive pressure generating groove.
[0121] Furthermore, while we have described the sealed fluid side as the high-pressure side and the leak side as the low-pressure side, the sealed fluid side may be the low-pressure side and the leak side the high-pressure side, or the sealed fluid side and the leak side may be at approximately the same pressure.
[0122] Furthermore, although the sealed fluid F was described as a high-pressure liquid in Examples 1 to 5, it is not limited to this; it may also be a gas or a low-pressure liquid, or a mist-like mixture of liquid and gas.
[0123] Furthermore, although the leaking fluid in Examples 1 to 5 was described as atmospheric air A, which is a low-pressure gas, it is not limited to this; it may also be a liquid or a high-pressure gas, or a mist-like mixture of liquid and gas. [Explanation of Symbols]
[0124] 10. Static sealing ring (first sliding part) 11 Sliding surface 12 Land 14. First positive pressure generating groove (other grooves) 14B Relative rotation end (end section) 15. First positive pressure generating groove (groove 1) 15B Relative rotation end (end section) 16 Intersection 17 Dynamic pressure generation mechanism 20 Rotating sealing ring (second sliding part) 21 Sliding surface 22 Rand 24. Second positive pressure generation groove 24B Relative rotation end (end section) A atmosphere C Contamination D1~D3 Depth F Sealed fluid F1 1st force F2 2nd force S1 Internal space (space on the leakage side) S2 Outside space (sealed fluid space)
Claims
1. A pair of sliding parts positioned at a point where they rotate relative to each other in a rotating machine, wherein the sliding surfaces of the sliding parts slide relative to each other. Multiple first positive pressure generating grooves are provided on the sliding surface of the first sliding component, communicating with the leakage-side space and extending in the relative rotational direction of the second sliding component, with an end portion. The sliding surface of the second sliding component is provided with a plurality of second positive pressure generating grooves that communicate with the leakage-side space, extend in the relative rotational direction of the first sliding component, and have an end portion. The sliding surface of the first sliding component and the sliding surface of the second sliding component are configured to slide across each other 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 at least one groove whose terminal position is different from that of the other grooves. The first groove is a pair of sliding parts having an end portion located on the sealed fluid space side than the end portions of the other groove and the end portion of the second positive pressure generating groove.
2. The pair of sliding parts according to claim 1, wherein the end portion of the other groove is located on the sealed fluid space side than the end portion of the second positive pressure generating groove.
3. The pair of sliding parts according to claim 1, wherein the aforementioned groove is provided in a rotating sealing ring which is one of the pair of sliding parts.
4. A pair of sliding parts according to any one of claims 1 to 3, wherein the volume of the other groove is greater than the volume of the second positive pressure generating groove, and the volume of the first groove is greater than the volume of the other groove.
5. The pair of sliding parts according to claim 1, wherein the aforementioned grooves are equally spaced in the circumferential direction.