Sliding parts

Abstract

A sliding component is provided that can suppress wear between sliding surfaces from the start of relative rotation of a pair of sliding components to high-speed rotation, and can suppress leakage of a sealed fluid. A sliding component (10) is annular and is arranged at a portion of a rotating machine where relative rotation occurs, and slides relative to another sliding component (20). The sliding component (10) has a sliding surface (11) provided with: a plurality of first dynamic pressure generating grooves (14), which are arranged on a leakage side (S1), have a terminal (14B), and generate positive pressure; and a plurality of second dynamic pressure generating grooves (9), which are arranged on a sealed fluid side (S2), have a terminal (9B), and generate positive pressure, and a depth (D2) of the second dynamic pressure generating grooves (9) is shallower than a depth (D1) of the first dynamic pressure generating grooves (14).

Description

Technical Field

[0001] The present invention relates to relatively rotating sliding parts, for example, sliding parts used in shaft sealing devices for sealing rotating shafts of rotating machinery in automobiles, general industrial machinery, or other sealing fields, or sliding parts used in bearings of machinery in automobiles, general industrial machinery, or other bearing fields. Background Art

[0002] As a shaft sealing device to prevent leakage of a sealed fluid, for example, a mechanical seal includes a pair of annular sliding members that rotate relative to each other and slide against each other. In recent years, for environmental reasons, it has been desired to reduce the energy lost due to sliding in such mechanical seals.

[0003] For example, the mechanical seal shown in Patent Document 1 is composed of a pair of annular sliding parts that can rotate relative to each other, with a sealed fluid in the outer space and a low-pressure fluid in the inner space. A spiral groove is provided on one sliding part, which is connected to the inner space where the low-pressure fluid exists. The spiral groove extends in an arc shape from the inner diameter end toward the outer diameter side while tilting circumferentially. The terminal end of the spiral groove is closed downstream in the relative rotation direction. As a result, when the pair of sliding parts rotate relative to each other, the low-pressure fluid is introduced into the spiral groove of one sliding part, thereby generating positive pressure at the terminal end of the spiral groove and its vicinity, causing the sliding surfaces of the pair of sliding parts to slightly separate from each other, thereby achieving low friction. In addition, the spiral groove generates negative pressure at the starting end and its vicinity, sucking in the sealed fluid that flows from the outer space between the sliding surfaces, thereby preventing the sealed fluid from leaking from between the pair of sliding parts into the low-pressure inner space.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 62-31775 (pp. 2, 3, Figure 2 ) Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, in sliding components such as Patent Document 1, the spiral groove is arranged on the leakage side of a sliding component and extends from the inner diameter end to the outer diameter side in a manner that introduces low-pressure fluid into the inner space. Therefore, although it can achieve low wear and suppress leakage, it is impossible to generate sufficient dynamic pressure in the spiral groove before the sliding component reaches a high-speed rotation state above a certain level. It takes time for the sliding surfaces to separate from each other, and there is a possibility that the sliding surfaces will wear each other.

[0009] The present invention has been made in view of such problems, and an object of the present invention is to provide a sliding member capable of suppressing wear of sliding surfaces from the start of relative rotation of a pair of sliding members to high-speed rotation and preventing leakage of a sealed fluid.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, the sliding component of the present invention is annular, arranged at a relatively rotating part of a rotating machine, and slides relative to other sliding components, wherein the sliding surface of the sliding component is provided with: a plurality of first dynamic pressure generating grooves, the plurality of first dynamic pressure generating grooves being arranged on the leakage side, having a terminal, and generating positive pressure; and a plurality of second dynamic pressure generating grooves, the plurality of second dynamic pressure generating grooves being arranged on the sealed fluid side, having a terminal, and generating positive pressure, and the depth of the second dynamic pressure generating grooves being shallower than the depth of the first dynamic pressure generating grooves.

[0012] Because the depth of the second dynamic pressure generating groove is shallower than that of the first dynamic pressure generating groove, when the relative rotation speed of the sliding parts is low, the second force based on the positive pressure generated by the sealed fluid in the second dynamic pressure generating groove becomes the primary force, causing the sliding surfaces to separate. As the relative rotation speed of the sliding parts increases, the first force based on the positive pressure generated by the leakage-side fluid in the first dynamic pressure generating groove rapidly increases. When the relative rotation speed of the sliding parts is sufficiently high, the first force becomes greater than the second force, causing the first force to become the primary force, causing the sliding surfaces to separate. This suppresses wear between the sliding surfaces from low to high relative rotation speeds of the pair of sliding parts. Furthermore, when the relative rotation speed of the sliding parts is high, the gap formed between the sliding surfaces increases, making it less likely that positive pressure will be generated in the second dynamic pressure generating groove. Therefore, the first force based on the positive pressure generated in the first dynamic pressure generating groove becomes the primary force, allowing the sliding surfaces to separate stably. This allows the sliding surfaces to separate from the initial relative rotation of the pair of sliding parts until high-speed rotation occurs, thus suppressing wear. Furthermore, since the second dynamic pressure generating grooves draw in the sealed fluid flowing from the space on the sealed fluid side into between the sliding surfaces, leakage of the sealed fluid from between the pair of sliding members to the space on the leakage side can be prevented.

[0013] The second dynamic pressure generating groove may communicate with a space on the sealed fluid side.

[0014] This facilitates the introduction of the sealed fluid into the second dynamic pressure generating groove, and enables the positive pressure to be generated at an early stage.

[0015] An annular land portion may be provided between a terminal end of the first dynamic pressure generating groove and a terminal end of the second dynamic pressure generating groove. The land portion is continuous in the circumferential direction and has a width greater than or equal to a predetermined value in the radial direction.

[0016] Thus, when the sliding surfaces are separated by the second force based on the positive pressure generated in the second dynamic pressure generating groove, the land portion can be used to suppress the sealed fluid between the sliding surfaces from flowing into the space on the leakage side. In addition, when the pair of sliding components are stationary and not rotating relative to each other, leakage of the sealed fluid into the space on the leakage side can be suppressed.

[0017] The radial center of the land portion may be arranged closer to the sealed fluid side than the radial center of the sliding surface.

[0018] In this way, since the land portion is arranged radially close to the sealed fluid side on the sliding surface, the extension distance of the first dynamic pressure generating groove can be ensured to be longer, and multiple first dynamic pressure generating grooves can be arranged in an array, so that the first dynamic pressure generating groove becomes the main dynamic pressure generating source than the second dynamic pressure generating groove, thereby suppressing the leakage of the sealed fluid to the space on the leakage side.

[0019] A wall portion extending from a bottom surface toward the sliding surface may be formed at a terminal end of the second dynamic pressure generating groove.

[0020] Thus, when the sliding members rotate relatively, the sealed fluid is concentrated on the wall portion at the terminal end of the second dynamic pressure generating groove, and thus a positive pressure can be reliably generated near the terminal end.

[0021] An extension distance of the second dynamic pressure generating groove may be shorter than an extension distance of the first dynamic pressure generating groove.

[0022] This allows high positive pressure to be generated in the first dynamic pressure generating grooves when the pair of sliding members rotate at a relatively high speed, and allows positive pressure to be generated quickly in the second dynamic pressure generating grooves when the pair of sliding members rotate at a relatively low speed.

[0023] The second dynamic pressure generating groove may extend obliquely in the circumferential direction from the sealed fluid side toward the leakage side.

[0024] Thus, when the pair of sliding members rotate relative to each other, the sealed fluid is easily introduced into the second dynamic pressure generating groove, and positive pressure can be generated at an early stage.

[0025] The first dynamic pressure generating groove may extend obliquely in the circumferential direction from the leakage side toward the sealed fluid side, and the second dynamic pressure generating groove may be inclined further along the circumferential direction than the first dynamic pressure generating groove.

[0026] Thus, when the sliding members start to rotate relative to each other, the sealed fluid is easily introduced into the second dynamic pressure generating grooves, and thus a positive pressure can be generated in the second dynamic pressure generating grooves at an early stage.

[0027] The second dynamic pressure generating groove may be arranged on the outer diameter side of the sliding surface.

[0028] Thus, since the second dynamic pressure generating grooves are arranged at positions where the peripheral speed of the relative rotation of the sliding member is high, the sealed fluid is easily introduced into the second dynamic pressure generating grooves when the sliding member starts relative rotation.

[0029] In addition, the sealed fluid may be a gas or a liquid, or may be a mist mixture of liquid and gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a longitudinal sectional view showing an example of a mechanical seal according to an embodiment of the present invention.

[0031] Figure 2 This is a diagram showing the sliding surface of the stationary seal ring as viewed from the axial direction.

[0032] Figure 3 This is an enlarged view of the sliding surface of the stationary seal ring as viewed from the axial direction.

[0033] Figure 4 It is along Figure 2 Cross-sectional view along line AA.

[0034] Figure 5 It is a cross-sectional view schematically showing the first dynamic pressure generating groove and the second dynamic pressure generating groove.

[0035] Figure 6 This is an explanatory diagram showing the behavior of the fluid in the first dynamic pressure generating groove and the second dynamic pressure generating groove as viewed from the axial direction.

[0036] Figure 7 (a) to (c) are cross-sectional views schematically showing the separation between the sliding surfaces of a pair of sliding members at each relative rotational speed.

[0037] Figure 8 This is an explanatory diagram schematically showing an example of a mechanical seal according to a second embodiment of the present invention.

[0038] Figure 9 This is an explanatory diagram schematically showing an example of a mechanical seal according to a third embodiment of the present invention.

[0039] Figure 10 This is an explanatory diagram schematically showing an example of a mechanical seal according to a fourth embodiment of the present invention.

[0040] Figure 11 This is an explanatory diagram schematically showing an example of a mechanical seal according to a fifth embodiment of the present invention. DETAILED DESCRIPTION

[0041] Hereinafter, modes for implementing the sliding member of the present invention will be described based on examples.

[0042] Example 1

[0043] Reference Figures 1 to 7 The sliding component of Example 1 will be described. In this example, the sliding component is a mechanical seal. A sealed fluid exists outside the mechanical seal, while the atmosphere exists inside. The outer diameter side of the sliding component constituting the mechanical seal is the sealed fluid side (high-pressure side), and the inner diameter side is the leakage side (low-pressure side). For ease of explanation, grooves and other components formed on the sliding surface are sometimes indicated by dots in the drawings.

[0044] Figure 1 The mechanical seal shown is an inboard-type mechanical seal for general industrial machinery. It seals a sealed fluid F that leaks from the outer diameter side of the sliding surface toward the inner diameter side, and its inner space S1 is connected to the atmosphere A. In this embodiment, the sealed fluid F is a high-pressure liquid, and the atmosphere A is a gas at a lower pressure than the sealed fluid F.

[0045] The mechanical seal primarily comprises: an annular stationary seal ring 10 as a sliding component, mounted in a non-rotating but axially movable manner within a seal housing 5 secured to the housing 4 of the device to which it is mounted; and an annular rotating seal ring 20 as another sliding component, mounted on the rotating shaft 1 via a sleeve 2 so as to rotate integrally with the rotating shaft 1. In this mechanical seal, the stationary seal ring 10 is axially biased by the bellows 7, causing the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 to slide in close contact with each other. Furthermore, the sliding surface 21 of the rotating seal ring 20 is flat, without any recessed portions such as grooves.

[0046] The stationary seal ring 10 and the rotating seal ring 20 are typically formed from a combination of SiC (hard material) and SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited to these. Any sliding material that can be used as a sliding material for mechanical seals can be used. SiC includes materials composed of two or more phases with different components and compositions, such as sintered bodies containing boron, aluminum, carbon, etc. as sintering aids. Examples include SiC with dispersed graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, and SiC-TiN. Carbon includes resin-molded carbon and sintered carbon, such as carbon mixed with carbonaceous and graphite. In addition to the above-mentioned sliding materials, metal materials, resin materials, surface-modified materials (coating materials), and composite materials can also be used.

[0047] like Figure 2 and Figure 3As shown, the rotating seal ring 20 slides relative to the stationary seal ring 10 in the counterclockwise direction as indicated by the arrow. On the sliding surface 11 of the stationary seal ring 10, a plurality of (20 in Example 1) first dynamic pressure generating grooves 14 are evenly arranged along the circumferential direction on the inner diameter side, and a plurality of (20 in Example 1) second dynamic pressure generating grooves 9 are evenly arranged along the circumferential direction on the outer diameter side.

[0048] Furthermore, the portion of the sliding surface 11 outside the first dynamic pressure generating grooves 14 and the second dynamic pressure generating grooves 9 forms a flat land portion 12. Specifically, the land portion 12 includes a portion between circumferentially adjacent first dynamic pressure generating grooves 14, a portion between circumferentially adjacent second dynamic pressure generating grooves 9, and an annular land portion 12a between radially separated first and second dynamic pressure generating grooves 14 and 9. These portions are flush with the surface of the land portion 12 on the sliding surface 11 side (hereinafter referred to as the flat surface of the land portion 12). The annular land portion 12a will be described in detail later.

[0049] The first dynamic pressure generating groove 14 has an inner diameter end, i.e., a relative rotation start end 14A, that communicates with the inner space S1. The first dynamic pressure generating groove 14 extends in an arc shape from the start end 14A toward the outer diameter side, tilting toward the rotation terminal end of the rotary seal ring 20. The outer diameter end, i.e., the relative rotation terminal end 14B, of the first dynamic pressure generating groove 14 is closed by a wall portion 14b and is not in communication with the outer space S2. The first dynamic pressure generating groove 14 has an arc shape that bulges toward the outer diameter side.

[0050] Specifically, the first dynamic pressure generating groove 14 includes a bottom surface 14a that is flat from a starting end 14A to a terminal end 14B and parallel to the flat surface of the land portion 12; a wall portion 14b that extends perpendicularly from the edge of the terminal end 14B of the bottom surface 14a toward the sliding surface 11; and sidewall portions 14c and 14d that extend perpendicularly from both side edges of the bottom surface 14a toward the sliding surface 11. Furthermore, the angle formed between the wall portion 14b and the sidewall portion 14c is obtuse, while the angle formed between the wall portion 14b and the sidewall portion 14d is acute. The acute angle 14f of the wall portion 14b on the sidewall portion 14d side is located closer to the rotation terminal end of the rotary seal ring 20 than the obtuse angle 14e of the wall portion 14b on the sidewall portion 14c side.

[0051] These first dynamic pressure generating grooves 14 are arranged so that a plurality (six in Example 1) of first dynamic pressure generating grooves 14 overlap in the radial direction when viewed from the axial direction.

[0052] The outer diameter end of the second dynamic pressure generating groove 9, i.e., the relative rotation start end 9A, communicates with the outer space S2. The second dynamic pressure generating groove 9 extends in an arc shape from the start end 9A toward the inner diameter side, tilting toward the rotation terminal end of the rotary seal ring 20. The inner diameter end of the second dynamic pressure generating groove 9, i.e., the relative rotation terminal end 9B, is closed by a wall portion 9b and is not in communication with the inner space S1. The second dynamic pressure generating groove 9 has an arc shape that bulges toward the outer diameter side.

[0053] Specifically, the second dynamic pressure generating groove 9 includes a bottom surface 9a that is flat from its starting end 9A to its terminal end 9B and parallel to the flat surface of the land portion 12; a wall portion 9b that extends perpendicularly from the edge of the terminal end 9B of the bottom surface 9a toward the sliding surface 11; and side wall portions 9c and 9d that extend perpendicularly from both side edges of the bottom surface 9a toward the sliding surface 11. Furthermore, the angle formed between the wall portion 9b and the side wall portion 9c is obtuse, while the angle formed between the wall portion 9b and the side wall portion 9d is acute. The acute angle 9f of the wall portion 9b on the side wall portion 9d side is located closer to the rotation terminal end of the rotary seal ring 20 than the obtuse angle 9e of the wall portion 9b on the side wall portion 9c side.

[0054] These second dynamic pressure generating grooves 9 are arranged so that adjacent second dynamic pressure generating grooves 9 overlap in the radial direction when viewed from the axial direction.

[0055] Furthermore, the terminal end 9B of the second dynamic pressure generating groove 9 is positioned radially farther outward than the terminal end 14B of the first dynamic pressure generating groove 14. Specifically, an annular land portion 12a is provided between the terminal end 14B of the first dynamic pressure generating groove 14 and the terminal end 9B of the second dynamic pressure generating groove 9. The annular land portion 12a is continuous in the circumferential direction and has a constant width in the radial direction.

[0056] In addition, the length of the second dynamic pressure generating groove 9 from the starting end 9A to the terminal end 9B (i.e., the extension distance of the second dynamic pressure generating groove 9) is shorter than the length of the first dynamic pressure generating groove 14 from the starting end 9A to the terminal end 9B (i.e., the extension distance of the first dynamic pressure generating groove 14).

[0057] The second dynamic pressure generating grooves 9 are inclined further along the circumferential direction than the first dynamic pressure generating grooves 14. The radial center of the annular land portion 12a is provided on the outer diameter side than the radial center of the sliding surface 11.

[0058] like Figure 4 and Figure 5 As shown, the first dynamic pressure generating groove 14 has a constant depth D1 from the start end 14A to the end end 14B. In this embodiment, the depth D1 is 10 μm.

[0059] The second dynamic pressure generating groove 9 has a constant depth D2 from the start end 9A to the end end 9B. In this embodiment, the depth D2 is 0.5 μm.

[0060] The depth D2 of the second dynamic pressure generating groove 9 is shallower than the depth D1 of the first dynamic pressure generating groove 14 (D2 < D1), and preferably, the depth D2 is 1 / 2 to 1 / 20 times the depth D1.

[0061] In addition, Figure 5 is a schematic cross-sectional view assuming a state where one first dynamic pressure generating groove 14 and one second dynamic pressure generating groove 9 are cut along the length direction respectively.

[0062] Next, use Figure 6 and Figure 7 to explain the operation when the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other. First, when the rotating seal ring 20 does not rotate during non-operation of a general industrial machine, the sealed fluid F flows into the second dynamic pressure generating groove 9. In addition, since the stationary seal ring 10 is urged by the bellows 7 toward the rotating seal ring 20, the sliding surfaces 11 and 21 are in contact with each other, and the amount of the sealed fluid F leaking from between the sliding surfaces 11 and 21 into the inner space S1 is almost zero.

[0063] At low speed just after the rotating seal ring 20 starts to rotate relative to the stationary seal ring 10, as shown in (a) of Figure 6 and Figure 7 , the sealed fluid F in the second dynamic pressure generating groove 9 moves following the rotation direction of the rotating seal ring 20 due to the friction with the sliding surface 21, and the sealed fluid F in the outer space S2 is introduced into the second dynamic pressure generating groove 9. That is, in the second dynamic pressure generating groove 9, the sealed fluid F moves from the start end 9A toward the terminal end 9B as shown by the arrow H1. In addition, for the flow of the sealed fluid F or the atmosphere A in Figure 6 , it is schematically shown without specifying the relative rotation speed of the rotating seal ring 20.

[0064] The sealed fluid F moving toward the terminal end 9B has an increased pressure at the acute angle portion 9f of the wall portion 9b of the second dynamic pressure generating groove 9 and its vicinity. That is, a positive pressure is generated at the acute angle portion 9f and its vicinity.

[0065] Since the depth D2 of the second dynamic pressure generating groove 9 is shallow, for a low rotation speed of the rotating seal ring 20, even if the amount of movement of the sealed fluid F is small, a positive pressure is generated at the acute angle portion 9f of the wall portion 9b of the second dynamic pressure generating groove 9 and its vicinity.

[0066] The second force F2, based on the positive pressure generated at and near the acute angle 9f, slightly separates the sliding surfaces 11 and 21. This causes the sealed fluid F within the second dynamic pressure generating groove 9, indicated by arrow H2, to flow between the sliding surfaces 11 and 21. The presence of sealed fluid F between the sliding surfaces 11 and 21 improves lubricity even during low-speed rotation, thus suppressing wear between the sliding surfaces 11 and 21. Furthermore, since the floating distance between the sliding surfaces 11 and 21 is small, leakage of the sealed fluid F into the inner space S1 is minimal.

[0067] On the other hand, since the depth D1 of the first dynamic pressure generating groove 14 is deeper than the depth D2 of the second dynamic pressure generating groove 9, when the relative rotation of the rotating seal ring 20 and the stationary seal ring 10 is low speed, the atmosphere A is not dense enough in the second dynamic pressure generating groove 9 and a high positive pressure is not generated. The first force F1 (at Figure 7 Therefore, when the rotary seal ring 20 rotates at a low speed, the second force F2 becomes the main force and separates the sliding surfaces 11 and 21 from each other.

[0068] When the relative rotation speed of the rotary seal ring 20 becomes higher, as shown in FIG. Figure 6 and Figure 7 As shown in (b), the atmosphere A in the first dynamic pressure generating groove 14 follows the rotation direction of the rotary seal ring 20 due to friction with the sliding surface 21, and the atmosphere A in the inner space S1 is drawn into the first dynamic pressure generating groove 14. That is, within the first dynamic pressure generating groove 14, a large amount of atmosphere A moves from the starting end 14A toward the terminal end 14B as indicated by arrow L1.

[0069] The atmospheric air A moving toward the terminal end 14B increases in pressure at and near the acute angle portion 14f of the wall portion 14b of the first dynamic pressure generating groove 14. That is, positive pressure is generated at and near the acute angle portion 14f.

[0070] The first force F1 based on the positive pressure generated at the acute angle portion 14f and its vicinity acts on the Figure 7 Compared with (a), the sliding surfaces 11 and 21 are further separated. As a result, the atmosphere A flows between the sliding surfaces 11 and 21 mainly into the first dynamic pressure generating grooves 14 indicated by arrow L2.

[0071] The atmosphere A in the first dynamic pressure generating groove 14 indicated by the arrow L2 pushes the sealed fluid F near the terminal end 14B of the first dynamic pressure generating groove 14 back to the outer space S2 side, so that the sealed fluid F leaking into the first dynamic pressure generating groove 14 or the inner space S1 is small.

[0072] In addition, through Figure 7(a) The sliding surfaces 11 and 21 are further separated, thereby making it easier for the sealed fluid F in the second dynamic pressure generating groove 9 to escape between the sliding surfaces 11 and 21. Figure 7 Compared with (a), the second force F2' becomes smaller.

[0073] Furthermore, at this time, the sealed fluid F surrounding the portion of the first dynamic pressure generating groove 14 other than the acute angle portion 14f is drawn into the first dynamic pressure generating groove 14 as indicated by arrow H3 due to the negative pressure generated in the first dynamic pressure generating groove 14. This tendency is most pronounced near the starting end 14A. The sealed fluid F drawn into the first dynamic pressure generating groove 14 returns from the terminal end 14B of the first dynamic pressure generating groove 14 to between the sliding surfaces 11 and 21.

[0074] On the other hand, since the sealed fluid F near the acute angle portion 14 f of the first dynamic pressure generating groove 14 is at high pressure as described above, it remains located in the land portion 12 as indicated by arrow H4 and hardly enters the first dynamic pressure generating groove 14 .

[0075] As described above, the first dynamic pressure generating grooves 14 are configured so that a plurality of first dynamic pressure generating grooves 14 overlap in the radial direction. Therefore, the sealed fluid F that moves from the acute angle portion 14f of another first dynamic pressure generating groove 14 adjacent to a certain first dynamic pressure generating groove 14 on the rotation starting end side of the rotating sealing ring 20 to the land portion 12 will be sucked in by the negative pressure generated in the first dynamic pressure generating groove 14, thereby preventing the sealed fluid F from leaking into the inner space S1.

[0076] When the relative rotation speed of the rotary seal ring 20 is further increased and reaches high-speed rotation (i.e., stable operation state), as shown in FIG. Figure 6 and Figure 7 As shown in (c), the inflow rate of the atmosphere A introduced into the first dynamic pressure generating groove 14 (refer to Figure 7 The arrow L1' of (c) further increases to generate a high positive pressure, and the first force F1' becomes larger. Figure 7 Compared with (b), the sliding surfaces 11 and 21 are separated by a longer floating distance Y. Figure 7 Compared to (b), more of the atmospheric air A in the first dynamic pressure generating groove 14 indicated by the arrow L2 ′ flows into between the sliding surfaces 11 , 21 .

[0077] The atmosphere A in the first dynamic pressure generating groove 14 indicated by the arrow L2' pushes the sealed fluid F near the terminal end 14B of the first dynamic pressure generating groove 14 back to the outer space S2 side, so that the sealed fluid F leaking into the first dynamic pressure generating groove 14 or the inner space S1 is small.

[0078] In this embodiment, when the floating distance Y increases due to the high-speed rotation of the rotary seal ring 20, the sealed fluid F in the second dynamic pressure generating groove 9 becomes more likely to escape between the sliding surfaces 11 and 21, and the positive pressure generated in the second dynamic pressure generating groove 9 decreases to a negligible level. Therefore, when the rotary seal ring 20 rotates at high speed, the first force F1 becomes the main force, causing the sliding surfaces 11 and 21 to separate from each other.

[0079] As described above, the depth D2 of the second dynamic pressure generating groove 9 is shallower than the depth D1 of the first dynamic pressure generating groove 14. Therefore, when the relative rotation speed of the rotating seal ring 20 is low, the second force F2 based on the positive pressure generated by the sealed fluid F in the second dynamic pressure generating groove 9 becomes the main force, causing the sliding surfaces 11 and 21 to separate from each other. As the relative rotation speed of the rotating seal ring 20 increases, the first force F1 based on the positive pressure generated by the atmosphere A in the first dynamic pressure generating groove 14 increases rapidly. When the relative rotation speed of the rotating seal ring 20 becomes sufficiently high, the first force F1 becomes greater than the second force F2. Therefore, the first force F1 becomes the main force, causing the sliding surfaces 11 and 21 to separate from each other. This makes it possible to suppress wear between the sliding surfaces 11 and 21 from the time when the relative rotation speed of the stationary seal ring 10 and the rotating seal ring 20 is low to the time when the relative rotation speed is high.

[0080] Furthermore, when the rotating seal ring 20 rotates at high speed, the gap formed between the sliding surfaces 11 and 21 increases, making it difficult for positive pressure to be generated in the second dynamic pressure generating groove 9. First force F1, based on the positive pressure generated in the first dynamic pressure generating groove 14, becomes the primary force, allowing the sliding surfaces 11 and 21 to be stably separated from each other. Consequently, the sliding surfaces 11 and 21 can be separated from each other from the time the stationary seal ring 10 and the rotating seal ring 20 begin relative rotation until high-speed rotation occurs, thereby suppressing wear.

[0081] Furthermore, since the second dynamic pressure generating grooves 9 communicate with the external space S2 , the sealed fluid F can be easily introduced into the second dynamic pressure generating grooves 9 , and positive pressure can be generated at an early stage.

[0082] Furthermore, since an annular land portion 12a, which is continuous in the circumferential direction and has a constant radial width, is provided between the terminal end 14B of the first dynamic pressure generating groove 14 and the terminal end 9B of the second dynamic pressure generating groove 9, when the sliding surfaces 11 and 21 are separated from each other by the second force F2 based on the positive pressure generated by the second dynamic pressure generating groove 9, the annular land portion 12a can suppress the sealed fluid F between the sliding surfaces 11 and 21 from flowing into the inner space S1. Furthermore, when the stationary seal ring 10 and the rotating seal ring 20 are stationary and not rotating relative to each other, leakage of the sealed fluid F into the inner space S1 can be suppressed.

[0083] Furthermore, since the radial center of the annular land portion 12a is positioned closer to the sealed fluid than the radial center of the sliding surface 11, the extension distance of the first dynamic pressure generating groove 14 can be ensured to be longer, and multiple first dynamic pressure generating grooves 14 can be arranged in parallel. As a result, the first dynamic pressure generating grooves 14 become a more significant source of dynamic pressure generation than the second dynamic pressure generating grooves 9, thereby suppressing leakage of the sealed fluid F into the inner space S1. The radial center of the annular land portion 12a is the radial position obtained by adding the outer and inner diameters of the annular land portion 12a and dividing the sum by two, while the radial center of the sliding surface 11 is the radial position obtained by adding the outer and inner diameters of the sliding surface 11 and dividing the sum by two.

[0084] Furthermore, since the depth of the second dynamic pressure generating groove 9 is set to a dimension that can reliably reduce the influence of the positive pressure generated in the second dynamic pressure generating groove 9 when the rotary seal ring 20 rotates at high speed, the sliding surfaces 11 and 21 can be reliably separated by the first force F1 based on the positive pressure generated in the first dynamic pressure generating groove 14.

[0085] In addition, since a wall portion 9b extending from the bottom surface 9a toward the sliding surface 11 is formed at the terminal end 9B of the second dynamic pressure generating groove 9, when the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other, the sealed fluid F is concentrated on the acute angle portion 9f of the wall portion 9b at the terminal end 9B of the second dynamic pressure generating groove 9, so that positive pressure can be reliably generated near the terminal end 9B.

[0086] In addition, since the extension distance of the second dynamic pressure generating groove 9 is shorter than the extension distance of the first dynamic pressure generating groove 14, when the stationary sealing ring 10 and the rotating sealing ring 20 rotate at a relatively high speed, a high positive pressure can be generated in the first dynamic pressure generating groove 14, and when they rotate at a relatively low speed, a positive pressure can be generated in the second dynamic pressure generating groove 9 in advance.

[0087] Furthermore, since the second dynamic pressure generating groove 9 extends obliquely from the starting end 9A toward the inner diameter side and toward the rotation terminal end side of the rotary seal ring 20, when the stationary seal ring 10 and the rotary seal ring 20 rotate relative to each other, the sealed fluid F is easily introduced into the second dynamic pressure generating groove 9, enabling positive pressure to be generated in advance.

[0088] Furthermore, since the first dynamic pressure generating groove 14 extends obliquely from the starting end 14A toward the outer diameter toward the rotation terminal end side of the rotary seal ring 20, the second dynamic pressure generating groove 9 is inclined more along the circumferential direction than the first dynamic pressure generating groove 14. Therefore, when the stationary seal ring 10 and the rotary seal ring 20 start to rotate relative to each other, it is easy to introduce the sealed fluid F into the second dynamic pressure generating groove 9, so that positive pressure can be generated in the second dynamic pressure generating groove 9 in advance.

[0089] Furthermore, since the second dynamic pressure generating groove 9 is arranged on the outer diameter side of the sliding surface 11, the second dynamic pressure generating groove 9 is arranged at a position where the circumferential speed of the relative rotation of the rotating seal ring 20 is high. Therefore, when the stationary seal ring 10 and the rotating seal ring 20 start to rotate relative to each other, it is easy to introduce the sealed fluid F into the second dynamic pressure generating groove 9.

[0090] Furthermore, the terminal ends 14B of the first dynamic pressure generating grooves 14 and the terminal ends 9B of the second dynamic pressure generating grooves 9 are arranged so as not to overlap in the radial direction. This distance between the terminal ends 14B and 9B creates a positive pressure near the terminal ends 9B of the second dynamic pressure generating grooves 9. This makes it less likely that the sealed fluid F moving between the sliding surfaces 11 and 21 will flow into the second dynamic pressure generating grooves 9, and the sealed fluid F will be less likely to leak into the inner space S1. Furthermore, the first force F1 of the first dynamic pressure generating grooves 14 and the second force F2 of the second dynamic pressure generating grooves 9 are generated at locations that do not overlap in the radial direction. This allows for balanced force application between the sliding surfaces 11 and 21, resulting in separation between the sliding surfaces 11 and 21.

[0091] The depth D1 and the depth D2 are not limited to those in the first embodiment, and can be freely changed as long as the depth D2 is formed shallower than the depth D1.

[0092] Example 2

[0093] Next, refer to Figure 8 The mechanical seal of Example 2 is described. In addition, the repeated structural description of the same structure as the above embodiment is omitted. Figure 8 In the figure, the length from the start end to the end end of the first dynamic pressure generating groove is shown to be shorter than the actual length.

[0094] like Figure 8 As shown, the bottom surface 140 a of the first dynamic pressure generating groove 140 of the stationary seal ring 100 of the second embodiment is inclined so that the axial dimension gradually decreases from the starting end 140A toward the terminal end 140B.

[0095] The depth D2 of the second dynamic pressure generating groove 9 is deeper than the depth near the terminal end 140B of the first dynamic pressure generating groove 140, but shallower than the depth D3 of the deepest part (deepest portion) of the first dynamic pressure generating groove 140 (D2 <D3)。

[0096] Thus, because the depth D2 of the second dynamic pressure generating groove 9 is shallower than the depth D3 of the deepest portion of the first dynamic pressure generating groove 140, when the relative rotation of the rotary seal ring 20 is at a low speed, the second force based on the positive pressure generated by the sealed fluid F in the second dynamic pressure generating groove 9 becomes the main force, and the sliding surfaces 11 and 21 can be separated from each other. In addition, positive pressure is easily generated near the terminal end 140B of the first dynamic pressure generating groove 140.

[0097] Example 3

[0098] Next, refer to Figure 9 The mechanical seal of Example 3 is described. In addition, the repeated structural description of the same structure as the above embodiment is omitted. Figure 9 In the figure, the length from the start end to the end end of the first dynamic pressure generating groove is shown to be shorter than the actual length.

[0099] like Figure 9 As shown, the bottom surface 240 a of the first dynamic pressure generating groove 240 of the stationary seal ring 101 of the third embodiment is formed in a stepped shape from the starting end 240A to the terminal end 240B.

[0100] Specifically, with the center of the first dynamic pressure generating groove 240 in the longitudinal direction as the boundary, a deep bottom surface 240c having a large axial dimension is provided on the starting end 240A side of the bottom surface 240a, and a shallow bottom surface 240d having a small axial dimension is provided on the terminal end 240B side of the bottom surface 240a. Furthermore, an intermediate wall portion 240e is provided, extending perpendicularly from the edge of the deep bottom surface 240c toward the shallow bottom surface 240d, and a wall portion 240b is provided, extending perpendicularly from the edge of the shallow bottom surface 240d toward the sliding surface 11.

[0101] The depth D2 of the second dynamic pressure generating groove 9 is shallower than the depth D4 of the first dynamic pressure generating groove 240 (specifically, the depth of the deepest portion (deepest part) of the first dynamic pressure generating groove 240). Furthermore, while the bottom surface 240a of the first dynamic pressure generating groove 240 has been described as having a two-step structure, this is not limiting and may also have three or more steps.

[0102] Furthermore, in Examples 1 to 3 above, the second dynamic pressure generating groove 9 has a constant depth D2 from its starting end 9A to its terminal end 9B. However, this is not limiting. For example, the bottom surface may be inclined so that the depth gradually decreases from the starting end toward the terminal end, or may be formed in a stepped shape. In other words, the deepest portion of the second dynamic pressure generating groove only needs to be shallower than the deepest portion of the first dynamic pressure generating groove.

[0103] Example 4

[0104] Next, refer to Figure 10 A mechanical seal according to Example 4 will be described. Note that redundant descriptions of components having the same configuration as in the above-described embodiment will be omitted.

[0105] like Figure 10 As shown, the terminal end 340B of the first dynamic pressure generating groove 340 of the stationary seal ring 102 of the fourth embodiment overlaps with the terminal end 9B of the second dynamic pressure generating groove 9 in the radial direction.

[0106] Thus, the first force of the first dynamic pressure generating groove 340 and the second force of the second dynamic pressure generating groove 9 are generated at radially overlapping positions, thereby enabling the sliding surfaces 11 and 21 to be greatly separated from each other in a short time, thereby enabling the sliding surfaces 11 and 21 to quickly exert high lubricity to each other.

[0107] Example 5

[0108] Next, refer to Figure 11 A mechanical seal according to Example 5 will be described. Note that redundant descriptions of components identical to those of the above-described examples will be omitted.

[0109] like Figure 11 As shown, the first dynamic pressure generating groove 440 of the stationary seal ring 103 of the fifth embodiment extends so that the side walls 440c and 440d approach each other toward the terminal end 440B, with the terminal end 440B gradually tapering. Furthermore, the second dynamic pressure generating groove 190 extends so that the side walls 190c and 190d approach each other toward the terminal end 190B, with the terminal end 190B gradually tapering.

[0110] Thus, when the rotary seal ring 20 relatively rotates, positive pressure is easily generated near the terminal end 440B of the first dynamic pressure generating groove 440 and near the terminal end 190B of the second dynamic pressure generating groove 190 .

[0111] While 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 modifications and additions without departing from the gist of the present invention are also encompassed by the present invention.

[0112] For example, in the above embodiments, mechanical seals used in general industrial machinery are used as sliding components. However, other mechanical seals used in automobiles, water pumps, etc. may also be used. Furthermore, the present invention is not limited to mechanical seals and may also include sliding components other than mechanical seals, such as sliding bearings.

[0113] Furthermore, in the above embodiment, an example in which the first dynamic pressure generating groove and the second dynamic pressure generating groove are provided in the stationary seal ring has been described. However, the first dynamic pressure generating groove and the second dynamic pressure generating groove may also be provided in the rotating seal ring.

[0114] In addition, the sealed fluid side is described as the high-pressure side and the leakage side as the low-pressure side, but 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.

[0115] In addition, in the above embodiment, an inner-type mechanical seal is illustrated for sealing the sealed fluid F that is intended to leak from the outer diameter side to the inner diameter side of the sliding surface, but the present invention is not limited to this. An outer-type mechanical seal may also be used for sealing the sealed fluid F that is intended to leak from the inner diameter side to the outer diameter side of the sliding surface.

[0116] In addition, if Figure 2 As shown, the first dynamic pressure generating grooves and the second dynamic pressure generating grooves are provided on the sliding surface 11 of the stationary seal ring 10 in the same number, but the present invention is not limited thereto and the numbers may be different.

[0117] In addition, the following example is described: the extension distance of the second dynamic pressure generating groove is shorter than the extension distance of the first dynamic pressure generating groove, the second dynamic pressure generating groove is inclined in a circumferential manner, and the radial center of the annular land portion 12a is set to be closer to the outer diameter side than the radial center of the sliding surface 11, but is not limited to this. It is also possible that the extension distance of the first dynamic pressure generating groove is shorter than the extension distance of the second dynamic pressure generating groove, or the first dynamic pressure generating groove is inclined in a circumferential manner.

[0118] Furthermore, although the example in which the first dynamic pressure generating groove communicates with the inner space has been described, the present invention is not limited thereto and may not communicate as long as dynamic pressure can be generated.

[0119] Furthermore, although the example in which the second dynamic pressure generating groove communicates with the external space has been described, the present invention is not limited thereto and may not communicate as long as dynamic pressure can be generated.

[0120] In addition, the following example is described: an annular land portion 12a is provided between the first dynamic pressure generating groove and the second dynamic pressure generating groove, and the first dynamic pressure generating groove and the second dynamic pressure generating groove are arranged radially separated, but not limited to this. For example, it is also possible that the terminal end of the second dynamic pressure generating groove is arranged at a position closer to the inner diameter side than the terminal end of the first dynamic pressure generating groove, and the terminal end of the first dynamic pressure generating groove and the terminal end of the second dynamic pressure generating groove overlap in the circumferential direction.

[0121] In addition, in this embodiment, the sealed fluid F is described as a high-pressure liquid, but is not limited thereto and may be a gas or a low-pressure liquid, or may be a mist mixture of liquid and gas.

[0122] In addition, in this embodiment, the example in which the fluid on the leakage side is the atmosphere A which is a low-pressure gas is described, but the present invention is not limited thereto and may be liquid or high-pressure gas, or may be a mist mixture of liquid and gas.

[0123] In Examples 2 and 3, the depth of the dynamic pressure generating grooves is the deepest depth, but the depth of the dynamic pressure generating grooves may be any depth as long as the depth substantially contributes to the generation of positive pressure.

[0124] Description of labels

[0125] 9: Second dynamic pressure generating groove; 10: Stationary sealing ring (sliding component); 11: Sliding surface; 12a: Annular land portion (land portion); 14: First dynamic pressure generating groove; 14a: Bottom surface; 14b: Wall portion; 20: Rotating sealing ring (other sliding component); 21: Sliding surface; A: Atmosphere; D1, D2: Depth; F: Sealed fluid; F1: First force; F2: Second force; S1: Inner space; S2: Outer space; Y: Floating distance.

Claims

1. A sliding component, which is annular and is arranged at a relatively rotating part of a rotating machine and slides relative to other sliding components, wherein: The sliding surface of the sliding component includes: a plurality of first dynamic pressure generating grooves, the plurality of first dynamic pressure generating grooves being arranged on the leakage side, having terminal ends, and generating positive pressure; as well as a plurality of second dynamic pressure generating grooves, each of which is arranged on the sealed fluid side, has a terminal end, and generates positive pressure; The depth of the second dynamic pressure generating groove is shallower than the depth of the first dynamic pressure generating groove. The first dynamic pressure generating groove is connected to the space on the leakage side. The terminal end of the first dynamic pressure generating groove and the terminal end of the second dynamic pressure generating groove are separated in the radial direction. A land portion that is continuous over the entire circumference is provided between a terminal end of the first dynamic pressure generating groove and a terminal end of the second dynamic pressure generating groove.

2. The sliding component according to claim 1, wherein The second dynamic pressure generating groove communicates with a space on the sealed fluid side.

3. The sliding component according to claim 1 or 2, wherein: The radial center of the land portion is arranged closer to the sealed fluid side than the radial center of the sliding surface.

4. The sliding component according to claim 1 or 2, wherein: A wall portion extending from a bottom surface toward a sliding surface is formed at a terminal end of the second dynamic pressure generating groove.

5. The sliding component according to claim 1 or 2, wherein An extension distance of the second dynamic pressure generating groove is shorter than an extension distance of the first dynamic pressure generating groove.

6. The sliding component according to claim 1 or 2, wherein: The second dynamic pressure generating groove extends obliquely in the circumferential direction from the sealed fluid side toward the leakage side.

7. The sliding component according to claim 6, wherein The first dynamic pressure generating groove extends from the leakage side toward the sealed fluid side while being inclined in the circumferential direction, and the second dynamic pressure generating groove is inclined further along the circumferential direction than the first dynamic pressure generating groove.

8. The sliding component according to claim 1 or 2, wherein: The second dynamic pressure generating groove is arranged on the outer diameter side of the sliding surface.

9. A sliding component, which is annular and is disposed at a relatively rotating portion of a rotating machine and slides relative to other sliding components, wherein: The sliding surface of the sliding component includes: a plurality of first dynamic pressure generating grooves, the plurality of first dynamic pressure generating grooves being arranged on the leakage side, having terminal ends, and generating positive pressure; as well as a plurality of second dynamic pressure generating grooves, each of which is arranged on the sealed fluid side, has a terminal end, and generates positive pressure; The depth of the second dynamic pressure generating groove is shallower than the depth of the first dynamic pressure generating groove. The first dynamic pressure generating groove is connected to the space on the leakage side. The second dynamic pressure generating groove extends obliquely in the circumferential direction from the sealed fluid side toward the leakage side. The first dynamic pressure generating groove extends from the leakage side toward the sealed fluid side while being inclined in the circumferential direction, and the second dynamic pressure generating groove is inclined further along the circumferential direction than the first dynamic pressure generating groove.

10. The sliding component according to claim 9, wherein The second dynamic pressure generating groove communicates with a space on the sealed fluid side.

11. The sliding component according to claim 9 or 10, wherein: The terminal end of the first dynamic pressure generating groove and the terminal end of the second dynamic pressure generating groove are separated in the radial direction. A land portion that is continuous over the entire circumference is provided between a terminal end of the first dynamic pressure generating groove and a terminal end of the second dynamic pressure generating groove.

12. The sliding component according to claim 11, wherein The radial center of the land portion is arranged closer to the sealed fluid side than the radial center of the sliding surface.

13. The sliding component according to claim 9 or 10, wherein: A wall portion extending from a bottom surface toward a sliding surface is formed at a terminal end of the second dynamic pressure generating groove.

14. The sliding component according to claim 9 or 10, wherein: An extension distance of the second dynamic pressure generating groove is shorter than an extension distance of the first dynamic pressure generating groove.

15. The sliding component according to claim 9 or 10, wherein: The second dynamic pressure generating groove is arranged on the outer diameter side of the sliding surface.

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