Sliding member

Abstract

The present invention provides a sliding member capable of exhibiting a sufficient foreign matter discharge effect in any case of high-speed rotation and low-speed rotation. A first dynamic pressure generating groove (13) and a second dynamic pressure generating groove (14) are formed in at least one of the sliding surfaces (11), and the first dynamic pressure generating groove (13) communicates with the space on the leakage side. The terminal position of the sealed fluid side of the second dynamic pressure generating groove (14) is closer to the sealed fluid side than the terminal position of the sealed fluid side of the first dynamic pressure generating groove. Moreover, the second dynamic pressure generating groove (14) is provided with an extension part (14c), and the extension part (14c) protrudes from the terminal part of the first dynamic pressure generating groove (13) to the sealed fluid side. A first dynamic pressure generation region (15) is formed on the fluid-to-be-sealed side between the extension sections (14c) of the second dynamic pressure generation grooves (14) adjacent in the circumferential direction, said first dynamic pressure generation region (15) comprising a plurality of minute recesses (16) that do not communicate with the space (S2) on the fluid-to-be-sealed side and the space (S1) on the leakage side.

Description

Technical Field

[0001] The present invention relates to sliding members that rotate relative to each other. For example, it relates to sliding members used in shaft sealing devices for shaft sealing of rotating shafts in rotating machinery for automobiles, general industrial machinery, or other sealing fields, or sliding members used in bearings of machinery in the fields of automobiles, general industrial machinery, or other bearings. Background Art

[0002] As a shaft sealing device for preventing leakage of a fluid to be sealed, for example, a mechanical seal has a pair of annular sliding members that rotate relative to each other and whose sliding surfaces slide against each other. In such a mechanical seal, in recent years, due to environmental countermeasures and other reasons, it has been desired to reduce energy losses caused by sliding and the like.

[0003] For example, the sliding member shown in Patent Document 1 is a mechanical seal in which a liquid to be sealed exists on the outer diameter side and a gas exists on the inner diameter side; it is provided with a spiral-shaped hydrodynamic pressure generating groove that communicates with the gas side on the sliding surface of one of the sliding members and is closed at one end of the sliding surface. When the sliding members rotate relative to each other, gas is introduced into the hydrodynamic pressure generating groove, and the hydrodynamic pressure generated at the end of the hydrodynamic pressure generating groove separates the two sliding surfaces from each other and forms a gas film therebetween, thereby achieving low friction.

[0004] In addition, the hydrodynamic pressure generating groove that uses gas in this spiral shape has a function of discharging foreign matter in the hydrodynamic pressure generating groove to the outside of the sliding surface by using the gas sucked from one end side in the radial direction during high-speed rotation. However, since all the multiple hydrodynamic pressure generating grooves in Patent Document 1 have the same radial length, there is a technical problem that foreign matter stays near the end of the hydrodynamic pressure generating groove and cannot be completely discharged to the outside of the sliding surface.

[0005] Thus, there is a sliding member that sets a change in the pressure gradient in the radial direction by lengthening the radial length of some of the hydrodynamic pressure generating grooves (for example, refer to Patent Document 2). Thereby, foreign matter is not likely to stay near the end of the hydrodynamic pressure generating groove, and the foreign matter discharge effect during high-speed rotation can be improved. Prior Art Documents Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 62-31775 (page 2, Figure 2) Patent Document 2: International Publication No. 2018 / 139232 (page 8, Figure 3) Summary of the Invention

[0007] However, when the hydrodynamic pressure generating groove rotates at high speed, through the shearing action with the opposed sliding surface, the pressure can be sufficiently increased on the terminal side, so that a good foreign matter discharging effect can be exerted. However, when rotating at low speed, since the pressure on the terminal side is low, there is a problem that it is difficult to exert a sufficient foreign matter discharging effect.

[0008] The present invention is made in view of such problems, and its object is to provide a sliding member that can exert a sufficient foreign matter discharging effect in any case of high-speed rotation and low-speed rotation of the sliding member.

[0009] To solve the above problems, the sliding member of the present invention is: A sliding member in which the sliding surfaces of a pair of sliding rings of the sliding member rotate relative to each other, partitioning a space on the sealed fluid side and a space on the leakage side, wherein, A first hydrodynamic pressure generating groove and a second hydrodynamic pressure generating groove are formed on at least one of the above sliding surfaces. The first hydrodynamic pressure generating groove communicates with the space on the leakage side. The terminal position of the second hydrodynamic pressure generating groove on the sealed fluid side is closer to the sealed fluid side than the terminal position of the first hydrodynamic pressure generating groove on the sealed fluid side, and, The second hydrodynamic pressure generating groove has an extension portion that protrudes from the terminal portion of the first hydrodynamic pressure generating groove toward the sealed fluid side; Between the extension portions of the second hydrodynamic pressure generating grooves adjacent in the circumferential direction, a first hydrodynamic pressure generating region composed of a plurality of minute recesses is formed on the sealed fluid side, and the minute recesses do not communicate with either the space on the sealed fluid side or the space on the leakage side. Accordingly, hydrodynamic pressure is generated in the first hydrodynamic pressure generating region formed by minute recesses between the extension portions of the second hydrodynamic pressure generating grooves adjacent in the circumferential direction, so that the formation of the fluid film can be maintained and complemented from the beginning of low-speed rotation, and the discharging performance of foreign matters can be improved. In addition, in the circumferential direction, the leakage side fluid and foreign matters flowing out from the minute recesses can be collected by the second hydrodynamic pressure generating groove, and the foreign matters can be discharged from the terminal of the second hydrodynamic pressure generating groove toward the space on the sealed fluid side.

[0010] The narrower width of the above minute recesses can be formed to be narrower than the narrower width of the above hydrodynamic pressure generating grooves. Accordingly, a table surface can be ensured at a position closer to the sealed fluid side at the terminals of the first hydrodynamic pressure generating groove and the second hydrodynamic pressure generating groove, and while preventing the leakage of the sealed fluid, the effect of generating hydrodynamic pressure by the minute recesses at low rotational speeds can be obtained.

[0011] On the side closer to the fluid to be sealed than the terminal of the second hydrodynamic pressure generating groove described above, a second hydrodynamic pressure generating region composed of a plurality of minute recesses may also be formed, and these minute recesses are not in communication with either the space on the fluid to be sealed side or the space on the leakage side. Accordingly, since hydrodynamic pressure is generated on the side closer to the fluid to be sealed than the terminal of the second hydrodynamic pressure generating groove during low-speed rotation, the reduction of friction during low-speed rotation and the effect of discharging foreign matter are improved.

[0012] The minute recesses constituting the first hydrodynamic pressure generating region formed between the extensions of the circumferentially adjacent second hydrodynamic pressure generating grooves may have the same shape as the minute recesses constituting the second hydrodynamic pressure generating region formed on the side closer to the fluid to be sealed than the terminal of the second hydrodynamic pressure generating groove. Accordingly, since the flow direction of the fluid guided by the minute recesses becomes constant, turbulence can be suppressed and the hydrodynamic pressure generating effect becomes stable.

[0013] At the position closest to the fluid to be sealed in the second hydrodynamic pressure generating region, an annular minute recess may also be formed. Accordingly, leakage of the fluid to be sealed can be prevented.

[0014] The minute recesses constituting the first hydrodynamic pressure generating region formed between the extensions of the circumferentially adjacent second hydrodynamic pressure generating grooves may be formed along the rotational direction of the opposing sliding surface. Accordingly, since there is no radial component in the minute recesses, it does not have an adverse effect on the sealing performance during stationary state, and for the fluid flowing out from the first hydrodynamic pressure generating groove towards the fluid to be sealed side, these minute recesses become a resistance to generate hydrodynamic pressure, and can effectively assist the hydrodynamic pressure generating effect during low-speed rotation.

[0015] The minute recesses constituting the first hydrodynamic pressure generating region formed between the extensions of the circumferentially adjacent second hydrodynamic pressure generating grooves may also have a radial component. Accordingly, a flow with a radial component is generated in the minute recesses, and the foreign matter discharging performance can be further improved.

[0016] In addition, the fluid to be sealed may be a gas or a liquid, or may be a mist form mixed with a liquid and a gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a longitudinal sectional view of an example of a mechanical seal in Embodiment 1 of the present invention. Figure 2 is a view of the sliding surface of the stationary seal ring in Embodiment 1 as observed axially. Figure 3It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 1 as observed axially. Figure 4 It is an explanatory view of the fluid flow in the first and second dynamic pressure generating grooves and the micro recesses on the sliding surface of the stationary seal ring in Embodiment 1 as observed axially during high-speed rotation. Figure 5 It is an explanatory view of the fluid flow in the first and second dynamic pressure generating grooves and the micro recesses on the sliding surface of the stationary seal ring in Embodiment 1 as observed axially during low-speed rotation. Figure 6 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 2 of the present invention as observed axially. Figure 7 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 3 of the present invention as observed axially. Figure 8 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 4 of the present invention as observed axially. Figure 9 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 5 of the present invention as observed axially. Figure 10 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 6 of the present invention as observed axially. Figure 11 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 7 of the present invention as observed axially. Figure 12 It is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 8 of the present invention as observed axially. Figure 13 It is a view of the sliding surface of the stationary seal ring in the outer type modification as observed axially. Detailed implementation mode

[0018] Hereinafter, the form of the sliding member for implementing the present invention will be described based on the embodiments. Embodiment 1

[0019] Hereinafter, reference is made to Figures 1 to 5 The sliding member according to the present Embodiment 1 will be described. In addition, in the present embodiment, the form of the sliding member as a mechanical seal is taken as an example for description. Further, the internal space of the mechanical seal is a space where the atmosphere A exists (hereinafter simply referred to as "the space on the leakage side") as S1. Further, the external space of the mechanical seal is a space where the fluid F to be sealed exists (hereinafter simply referred to as "the space on the fluid-to-be-sealed side") as S2. Further, the outer diameter side of the sliding member constituting the mechanical seal is taken as the fluid-to-be-sealed side (high pressure side), and the inner diameter side is taken as the leakage side (low pressure side) for description.

[0020] Figure 1The mechanical seal for an automobile shown belongs to the built-in type. It seals the sealed fluid F that has a leakage tendency from the outer diameter side to the inner diameter side of the sliding surface. The space S1 on the leakage side communicates with the atmosphere A. In this embodiment, the sealed fluid F is taken as an example in the form of high-pressure liquid, and the atmosphere A is a gas with a pressure lower than that of the sealed fluid F. In addition, the sealed fluid F is not limited to liquid, and can also be gas or a misty form formed by mixing liquid and gas. The fluid in the space S1 on the leakage side is not limited to gas, and can also be liquid or a misty form formed by mixing liquid and gas.

[0021] The mechanical seal mainly consists of a rotating seal ring 20 as a circular ring-shaped other sliding member and a stationary seal ring 10 as a circular ring-shaped sliding member. The rotating seal ring 20 is arranged on the rotating shaft 1 through a sleeve 2 in a state of being able to rotate together with the rotating shaft 1. The stationary seal ring 10 is arranged in a seal cover 5 fixed to the housing 4 of the installed equipment in a non-rotating and axially movable state. The stationary seal ring 10 is axially applied with a pre-tightening force by an elastic member 7. Accordingly, the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 are in close contact and slide with each other. It should be noted that the sliding surface 21 of the rotating seal ring 20 is a flat surface, and no concave portions such as grooves are provided on this flat surface.

[0022] The stationary seal ring 10 and the rotating seal ring 20 are typically formed of two SiCs (hard materials) or a combination of SiC (hard material) and carbon (soft material), but are not limited thereto. Any sliding material that can be used for mechanical seals can be applied. In addition, as SiC, sintered bodies with boron, aluminum, carbon, etc. as sintering aids and materials composed of two or more phases with different compositions can be used, such as SiC dispersed with graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, SiC-TiN, etc.; as carbon, carbon containing a mixture of carbonaceous and graphite, resin-molded carbon, sintered carbon, etc. can be used. In addition, metal materials, resin materials, surface-modified materials (coating materials), composite materials, etc. other than the above sliding materials can also be used.

[0023] As Figure 2 With Figure 3 As shown, the rotating seal ring 20, which is the relative-side seal ring with respect to the stationary seal ring 10, is arranged to slide in the counterclockwise direction shown by the solid-line arrow or in the clockwise direction shown by the dotted-line arrow, respectively. Hereinafter, the rotation direction shown by the solid-line arrow will be taken as the forward rotation direction, and the rotation direction shown by the dotted-line arrow will be taken as the reverse rotation direction for description.

[0024] On the sliding surface 11 of the stationary seal ring 10, a plurality of dynamic pressure generating grooves 13 and 14 with different lengths and different positions of radial terminals 13b and 14b are formed. In contrast, the start end 13a of the first dynamic pressure generating groove 13 with a relatively short radius is connected to the space S1 on the leakage side, and its terminal 13b is not connected to the space S2 on the fluid side to be sealed. In contrast, the start end 14a of the second dynamic pressure generating groove 14 with a relatively long radius is connected to the space S1 on the leakage side, and its terminal 14b is not connected to the space S2 on the fluid side to be sealed.

[0025] The second dynamic pressure generating grooves 14 are equally spaced in the circumferential direction on the sliding surface 11. Between adjacent second dynamic pressure generating grooves 14, a plurality of first dynamic pressure generating grooves 13 are provided at equal intervals in the circumferential direction. In the present embodiment, six second dynamic pressure generating grooves 14 are provided in the circumferential direction of the sliding surface 11. Three first dynamic pressure generating grooves 13 are provided between every two second dynamic pressure generating grooves 14.

[0026] Adjacent first dynamic pressure generating grooves 13 are spaced apart from each other at the same distance in the circumferential direction. Moreover, the interval distance between the first dynamic pressure generating groove 13 and the adjacent second dynamic pressure generating groove 14 is the same as the interval distance between the first dynamic pressure generating grooves 13. That is, all adjacent first dynamic pressure generating grooves 13 and second dynamic pressure generating grooves 14 are equally spaced in the circumferential direction. However, it is not limited thereto, and adjacent first dynamic pressure generating grooves 13 and second dynamic pressure generating grooves 14 may also be spaced apart at a distance different from the interval distance between the first dynamic pressure generating grooves 13 in the circumferential direction.

[0027] For the first dynamic pressure generating groove 13, its start end 13a is connected to the space S1 on the leakage side. The first dynamic pressure generating groove 13 is inclined from the start end 13a toward the outer diameter side in the forward rotation direction of the rotary seal ring 20 (the forward rotation direction of the relative rotation) and extends in an arc shape, and is a spiral groove that generates dynamic pressure at the terminal 13b when the rotary seal ring 20 rotates forward. Similarly, the start end 14a of the second dynamic pressure generating groove 14 is connected to the space S1 on the leakage side. The second dynamic pressure generating groove 14 extends from the start end 14a toward the outer diameter side in an arc shape with the same radius of curvature as the first dynamic pressure generating groove 13, and is a spiral groove that generates dynamic pressure at the terminal 14b when the rotary seal ring 20 rotates forward. It should be noted that the first and second dynamic pressure generating grooves 13 and 14 are not limited to being inclined and extending in an arc shape in the forward rotation direction of the rotary seal ring 20. For example, they may also be inclined and extend in a straight line in the forward rotation direction of the rotary seal ring 20 (the forward rotation direction of the relative rotation).

[0028] As Figure 3As shown, the terminal 13b of the first dynamic pressure generating groove 13 is located closer to the leakage side than the terminal 14b of the second dynamic pressure generating groove 14. That is, the second dynamic pressure generating groove 14 is formed to have an extension portion 14c that extends longer than the first dynamic pressure generating groove 13 in the radial direction toward the fluid to be sealed side.

[0029] In addition, at a position closer to the fluid to be sealed side than the terminal 13b of the first dynamic pressure generating groove 13, between the terminals 14b of the circumferentially adjacent second dynamic pressure generating grooves 14, that is, between the extension portions 14c, a plurality of arc-shaped grooves 16 serving as minute recesses are formed. The region where these plurality of arc-shaped grooves 16 are formed is referred to as the first dynamic pressure generating region 15. Specifically, in the present embodiment, the first dynamic pressure generating region 15 is composed of a plurality of arc-shaped grooves 16 that are spaced apart from each other in parallel at a predetermined interval in the radial direction of the sliding surface 11.

[0030] As Figure 3 shown, the arc-shaped groove 16 is not in communication with the space S1 on the leakage side and the space S2 on the fluid to be sealed side, and is also not in communication with the first and second dynamic pressure generating grooves 13 and 14. The arc-shaped groove 16 has an arc shape along the direction of relative rotation with respect to the sliding surface 21 of the opposed rotary seal ring 20. The two ends 16a and 16b of the arc-shaped groove 16 in the extending direction are respectively disposed near the terminals 14b of the adjacent second dynamic pressure generating grooves 14. From the viewpoints of preventing leakage and discharging foreign matters, it is preferable that the interval distance between the two ends 16a and 16b and the second dynamic pressure generating groove 14 is closer than the interval distance between the first dynamic pressure generating groove 13 and the adjacent second dynamic pressure generating groove 14.

[0031] The arc-shaped groove 16 closest to the leakage side constituting the dynamic pressure generating region 15 is close to the terminal 13b of the first dynamic pressure generating groove 13. The arc-shaped groove 16 closest to the fluid to be sealed side is disposed at a position where it does not protrude from the terminal 14b of the second dynamic pressure generating groove 14 toward the fluid to be sealed side.

[0032] In addition, the depth of each arc-shaped groove 16 is formed to be below the depths of the first and second dynamic pressure generating grooves 13 and 14. In addition, the narrower radial width among the circumferential width and the radial width of each arc-shaped groove 16 is narrower than the narrower circumferential width among the widths of the first and second dynamic pressure generating grooves 13 and 14. Also, the volume of each arc-shaped groove 16 is smaller than that of the first and second dynamic pressure generating grooves 13 and 14. Preferably, the depth of each arc-shaped groove 16 is 1 / 2 or less of that of the first and second dynamic pressure generating grooves 13 and 14, the width is 1 / 5 or less of that of the first and second dynamic pressure generating grooves 13 and 14, and the volume is 1 / 10 or less of that of the first and second dynamic pressure generating grooves 13 and 14.

[0033] In addition, the sliding surface 11 has a land that forms a flat surface on the same plane 17, 18, 19, 23. The tabletop 17 is the part circumferentially located between the first and second dynamic pressure generating grooves 13 and 14. The tabletop 18 is the part radially located between the arc grooves 16. The tabletop 19 is the part located between the terminal 14b of the second dynamic pressure generating groove 14 and the two ends 16a, 16b of the arc groove 16. The tabletop 23 is the part located closer to the fluid to be sealed side than the arc groove 16.

[0034] Next, use Figure 4 and Figure 5 to describe the operation when the stationary seal ring 10 and the rotating seal ring 20 rotate relative to each other. In addition, in this embodiment, the description will be made in the order of when the rotating seal ring 20 stops, rotates at a low speed, and rotates at a high speed.

[0035] First, when the rotating seal ring 20 is not rotating and stopped, the gas in the leakage side space S1 flows into the first dynamic pressure generating groove 13 from the starting end 13a. In addition, similarly, the gas in the leakage side space S1 flows into the second dynamic pressure generating groove 14 from the starting end 14a. The stationary seal ring 10 is biased toward the rotating seal ring 20 side by the elastic member 7. The sliding surfaces 11 and 21 are in contact with each other. Through the tabletop 23 that is retained in an arc shape closer to the fluid to be sealed side than the arc groove 16, it is possible to prevent the fluid to be sealed F in the fluid to be sealed side space S2 from leaking into the leakage side space S1. In addition, since there is no radial component in the arc groove 16, the multiple arc grooves 16 arranged radially can function like a labyrinth seal, improving the sealing performance at rest.

[0036] Next, the state at high speed rotation when the rotating seal ring 20 rotates at high speed in the forward rotation direction relative to the stationary seal ring 10, such as in a stable operation situation, will be described. As Figure 4 shown, at high speed rotation, the gas in the first dynamic pressure generating groove 13 follows the rotation direction of the rotating seal ring 20 by the shear action between the sliding surface 21 and moves toward the terminal 13b. Similarly, the gas in the second dynamic pressure generating groove 14 follows the rotation direction of the rotating seal ring 20 by the shear action between the sliding surface 21 and moves toward the terminal 14b.

[0037] Accordingly, dynamic pressure is generated at and near the terminal 13b of the first dynamic pressure generating groove 13 and at and near the terminal 14b of the second dynamic pressure generating groove 14. This dynamic pressure separates the sliding surfaces 11 and 21 from each other, and uses the fluid on the leakage side, that is, gas, to form a fluid film between the sliding surfaces 11 and 21, achieving the effect of reducing friction. In addition, since dynamic pressure is generated at the terminal 13b and the terminal 14b, and a negative pressure proportional to the dynamic pressure is generated at the starting end 13a and the starting end 14a side, gas is sucked into the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 from the starting end 13a and the starting end 14a.

[0038] In addition, by the dynamic pressure generated at the terminal 13b of the first dynamic pressure generating groove 13 and in its vicinity, and the dynamic pressure generated at the terminal 14b of the second dynamic pressure generating groove 14 and in its vicinity, foreign matters between the sliding surfaces 11 and 21 and the sealed fluid F can be effectively discharged to the outside between the sliding surfaces 11 and 21.

[0039] Specifically, dynamic pressure is generated at the terminal 13b of the first dynamic pressure generating groove 13 whose number is larger than that of the second dynamic pressure generating groove 14. In addition, dynamic pressure is also generated at the terminal 14b of the second dynamic pressure generating groove 14 that extends farther toward the sealed fluid side than the first dynamic pressure generating groove 13. Due to these dynamic pressures, the pressure gradient in the radial direction changes. Especially because the terminal 14b of the second dynamic pressure generating groove 14 is located near the sealed fluid side, foreign matters and the sealed fluid F can be effectively discharged to the outside between the sliding surfaces 11 and 21, that is, the space S2 that is easily discharged toward the sealed fluid side.

[0040] In addition, during high-speed rotation, the dynamic pressure effects generated by the first and second dynamic pressure generating grooves 13 and 14 play a dominant role, while the dynamic pressure effect generated by the arc-shaped groove 16 as a micro recess can be almost ignored.

[0041] In addition, since the number of the second dynamic pressure generating grooves 14 is smaller than that of the first dynamic pressure generating grooves 13, sufficient table surfaces can be ensured closer to the sealed fluid side than the terminals 13b and 14b of the first and second dynamic pressure generating grooves 13 and 14 to maintain the effect of preventing leakage of the sealed fluid F.

[0042] Next, the case of low-speed rotation when the rotary seal ring 20 just starts to rotate relative to the stationary seal ring 10 in the positive rotation direction will be described. As Figure 5 shown, even during low-speed rotation, the gas in the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 moves along the rotation direction of the rotary seal ring 20 due to the shearing action with the sliding surface 21. The gas in the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 moves toward the terminal 13b or the terminal 14b. Accordingly, the pressure rises at the terminal 13b and the terminal 14b respectively, and dynamic pressure is generated at the terminal 13b, the terminal 14b and in their vicinity. However, the dynamic pressure effect during low-speed rotation is lower than that during high-speed rotation.

[0043] Similarly, the gas in the arc-shaped groove 16 moves along with the rotation of the rotary seal ring 20 in the direction of rotation by the shearing action between the arc-shaped groove 16 and the sliding surface 21, and thus moves toward the terminal 16b. Accordingly, the pressure at the terminal 16b increases, and a dynamic pressure is generated at and near the terminal 16b. Since the volume of the arc-shaped groove 16 is set to be smaller than that of the first and second dynamic pressure generating grooves 13 and 14, a dynamic pressure can be generated at and near the terminal 16b of the arc-shaped groove 16 even when the rotary seal ring 20 is rotating at a low speed. In other words, the arc-shaped groove 16 can assist the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 in generating a dynamic pressure.

[0044] The dynamic pressure generating region 15 composed of a plurality of arc-shaped grooves 16 is located closer to the sealed fluid side than the terminal 13b of the first dynamic pressure generating groove 13 and near the terminal 14b of the second dynamic pressure generating groove 14. Accordingly, the dynamic pressure generated on the sealed fluid side between the sliding surfaces 11 and 21 can separate the sliding surfaces 11 and 21 from each other, and at the same time, it is easier to effectively discharge foreign matters to the outside between the sliding surfaces 11 and 21, that is, to the space S2 on the sealed fluid side. By quickly discharging the foreign matters that will resist rotation at an early stage before reaching high-speed rotation in this way, the relative rotation state between the sliding surfaces 11 and 21 can be made good.

[0045] Compared with the first dynamic pressure generating groove 13, the second dynamic pressure generating groove 14 extends longer in the radial direction. Thus, especially at low-speed rotation, the pressure at and near the terminal 14b is lower than that of the first dynamic pressure generating groove 13, that is, there is a tendency that it is difficult to fully obtain the dynamic pressure generating effect. The arc-shaped groove 16 is located closer to the sealed fluid side than the terminal 13b of the first dynamic pressure generating groove 13, and a dynamic pressure is generated at this position. That is, in addition to the dynamic pressure generated at the terminal 13b of the first dynamic pressure generating groove 13, a dynamic pressure is also generated at the terminal 16b of the arc-shaped groove 16, so that a higher foreign matter discharge effect can be achieved. In other words, the arc-shaped groove 16 can complement the dynamic pressure generating effect and the foreign matter discharge effect at low-speed rotation.

[0046] In addition, the dynamic pressure generated at the terminal 16b of the arc-shaped groove 16 can assist in the formation of the fluid film at low-speed rotation. Accordingly, the formation of the fluid film can be maintained and complemented from the very beginning of low-speed rotation, thereby suppressing the wear between the sliding surfaces 11 and 21.

[0047] In addition, the first dynamic pressure generating region 15 is formed between the terminals 14b of the adjacent second dynamic pressure generating grooves 14. Accordingly, in the circumferential direction, the second dynamic pressure generating groove 14 can collect the leakage-side fluid and foreign matters flowing out from the terminal 16b of the arc-shaped groove 16 and its vicinity, and the foreign matters can be discharged from the terminal 14b of the second dynamic pressure generating groove 14 toward the space S2 on the sealed fluid side.

[0048] In addition, the annular groove 16 is formed along the rotation direction of the sliding surface 21 opposite thereto. Since there is no radial component, the sealing performance at rest can be improved. In addition, as Figure 5 shown, for the fluid flowing out from the first hydrodynamic pressure generating groove 13 toward the sealed fluid side, the arc-shaped groove 16 will become a resistance. Accordingly, a hydrodynamic pressure as shown by the white arrow is generated, and the hydrodynamic pressure generation effect during low-speed rotation can be effectively assisted. Specifically, a part of the fluid flowing out from the first hydrodynamic pressure generating groove 13 flows into the side portion of the arc-shaped groove 16, and then hydrodynamic pressure is generated at the terminal 16b of the arc-shaped groove 16. In addition, the radial flow of the fluid flowing out from the first hydrodynamic pressure generating groove 13 can generate hydrodynamic pressure between the sliding surfaces 11 and 21 from the side portion of the arc-shaped groove 16 on the sealed fluid side. Embodiment 2

[0049] Next, with reference to Figure 6 the related content of the sliding member according to Embodiment 2 will be described. In addition, the description of the same configuration as in the above Embodiment 1 will be omitted.

[0050] The first hydrodynamic pressure generating region 35 of the present embodiment is composed of a plurality of radial grooves 36 as minute recesses extending in the radial direction on the sliding surface 11. The radial grooves 36 generate hydrodynamic pressure at the terminal 36b when the rotary seal ring 20 rotates forward. A radial component flow is generated in the radial grooves 36, and the foreign matter discharge performance can be further improved. In addition, since the radial grooves 36 are substantially orthogonal to the relative rotation direction, hydrodynamic pressure is easily generated even when the relative rotation speed is extremely low. Embodiment 3

[0051] Next, with reference to Figure 7 the related content of the sliding member according to Embodiment 3 will be described. In addition, the description of the same configuration as in the above Embodiment 1 will be omitted.

[0052] The first hydrodynamic pressure generating region 45 of the present embodiment is composed of a plurality of spiral grooves 46 which are minute recesses extending obliquely in the forward rotation direction of the rotary seal ring 20 and in an arc shape on the sliding surface 11. The spiral grooves 46 generate hydrodynamic pressure at the terminal 46b when the rotary seal ring 20 rotates forward. A radial and circumferential component flow is generated in the spiral grooves 46, and the foreign matter discharge performance can be further improved. In addition, since the spiral grooves 46 extend along a direction intersecting the relative rotation direction, relatively high hydrodynamic pressure is easily generated even during extremely low-speed relative rotation. Embodiment 4

[0053] Next, with reference to Figure 8The relevant content of the sliding member involved in Embodiment 4 will be described. In addition, the description of the same configurations as those in the above Embodiment 1 will be omitted.

[0054] As Figure 8 shown, on the sliding surface 11, in addition to the first hydrodynamic pressure generation region 15, a second hydrodynamic pressure generation region 55 is further formed. The second hydrodynamic pressure generation region 55 is composed of minute recesses, namely a plurality of annular grooves 56, provided on the fluid side to be sealed, closer to the fluid side than the terminal 14b of the second hydrodynamic pressure generation groove 14. In addition, the fluid inside the annular groove 56 is subjected to the shear force during relative rotation, and is laterally crossed by the fluid flowing toward the outer diameter side, thereby generating hydrodynamic pressure. By superimposing the hydrodynamic pressure effects generated by the second hydrodynamic pressure generation region 55, at low rotational speeds, the interface between the fluid on the leakage side and the fluid F to be sealed is pushed to a position closer to the fluid side to be sealed than the terminal 14b of the second hydrodynamic pressure generation groove 14. Accordingly, the foreign matter discharge effect is improved, and at the same time, leakage of the fluid to be sealed can be suppressed.

[0055] In addition, the arc groove 16 constituting the first hydrodynamic pressure generation region 15 and the annular groove 56 constituting the second hydrodynamic pressure generation region 55 are concentric circles and have the same shape. Accordingly, since the flow direction of the gas guided by the arc groove 16 and the annular groove 56 remains constant, turbulence can be suppressed, and the hydrodynamic pressure generation effect becomes stable. In addition, since the annular groove 56 is provided at a position closer to the fluid side to be sealed than the terminal 14b of the second hydrodynamic pressure generation groove 14, the sealing performance at rest can be improved. Embodiment 5

[0056] Next, with reference to Figure 9 the relevant content of the sliding member involved in Embodiment 5 will be described. In addition, the description of the same configurations as those in the above Embodiment 1 will be omitted.

[0057] As Figure 9 shown, on the sliding surface 11, a plurality of radial grooves 66, 67 are provided at predetermined intervals. The radial groove 66 is provided between the extension portions 14c of adjacent second hydrodynamic pressure generation grooves 14. The radial groove 66 extends to a position closer to the fluid side to be sealed than the terminal 14b of the second hydrodynamic pressure generation groove 14. The radial groove 66 constitutes a part of the first hydrodynamic pressure generation region between the extension portions 14c of adjacent second hydrodynamic pressure generation grooves 14, and a part of the second hydrodynamic pressure generation region closer to the fluid side to be sealed than between the terminals 14b of adjacent second hydrodynamic pressure generation grooves 14. In other words, the radial groove 66 is arranged such that the radial groove located between the extension portions 14c of adjacent second hydrodynamic pressure generation grooves 14 and the radial groove closer to the fluid side to be sealed than between the terminals 14b of adjacent second hydrodynamic pressure generation grooves 14 communicate with each other in the same shape.

[0058] The radial groove 67 is a minute recess provided closer to the fluid to be sealed than the terminal 14b of the second dynamic pressure generating groove 14. The radial groove 67 overlaps with the extending direction of the terminal 14b of the second dynamic pressure generating groove 14, and dynamic pressure is generated at the terminal 67b of the radial groove 67 and the terminal 66b of the radial groove 66, both of which are located on the fluid to be sealed side. By these dynamic pressures, at low rotational speeds, the interface between the fluid on the leakage side and the fluid F to be sealed can be effectively pushed to a position closer to the fluid to be sealed side than the terminal 14b of the second dynamic pressure generating groove 14. Accordingly, while improving the foreign matter discharge effect, leakage of the fluid F to be sealed can be suppressed. Example 6

[0059] Next, with reference to Figure 10 the relevant content of the sliding member related to Example 6 will be described. In addition, the description of the same configuration as in the above Example 1 will be omitted.

[0060] As Figure 10 shown, on the sliding surface 11, a plurality of spiral grooves 76, 77 are provided at predetermined intervals in the circumferential direction. The spiral groove 76 is provided between the extension portions 14c of adjacent second dynamic pressure generating grooves 14. The spiral groove 76 extends to a position closer to the fluid to be sealed than the terminal 14b of the second dynamic pressure generating groove 14. The spiral groove 76 constitutes a first dynamic pressure generating region between the extension portions 14c of adjacent second dynamic pressure generating grooves 14 and a part of a second dynamic pressure generating region closer to the fluid to be sealed side than between the terminals 14b of adjacent second dynamic pressure generating grooves 14. In other words, the spiral groove 76 is arranged such that the spiral groove between the extension portions 14c of the terminals 14b of adjacent second dynamic pressure generating grooves 14 and the spiral groove closer to the fluid to be sealed side than between the terminals 14b of adjacent second dynamic pressure generating grooves 14 communicate with each other in the same shape.

[0061] The spiral groove 77 is a minute recess provided closer to the fluid to be sealed than the terminal 14b of the second dynamic pressure generating groove 14. Dynamic pressure is generated at the terminal 77b of the spiral groove 77 and the terminal 76b of the spiral groove 76, both of which overlap with the extending direction of the terminal 14b of the second dynamic pressure generating groove 14 and are located on the fluid to be sealed side. By these dynamic pressures, at low rotational speeds, the interface between the fluid on the leakage side and the fluid to be sealed can be effectively pushed to a position closer to the fluid to be sealed side than the terminal 14b of the second dynamic pressure generating groove 14. Accordingly, while improving the foreign matter discharge effect, leakage of the fluid F to be sealed can be suppressed. Example 7

[0062] Next, with reference to Figure 11 the relevant content of the sliding member related to Example 7 will be described. In addition, the description of the same configuration as in the above Example 1 will be omitted.

[0063] AsFigure 11 As shown, on the sliding surface 11, in addition to the first dynamic pressure generation region 35, a second dynamic pressure generation region 55 is also formed. The first dynamic pressure generation region 35 is composed of a plurality of radial grooves 36 formed between the extension portions 14c of the second dynamic pressure generation groove 14. The second dynamic pressure generation region 55 is composed of a plurality of minute recesses, namely annular grooves 56, provided closer to the fluid to be sealed side than the terminal 14b of the second dynamic pressure generation groove 14. Accordingly, by superimposing the dynamic pressure effect generated by the first dynamic pressure generation region 35 and the dynamic pressure effect generated by the second dynamic pressure generation region 55, the foreign matter discharge performance can be further improved. In addition, the sealing performance at rest can be improved by the annular grooves 56. Example 8

[0064] Next, with reference to Figure 12 the relevant content of the sliding member related to Example 8 will be described. In addition, the description of the same configuration as in the above Example 1 will be omitted.

[0065] As Figure 12 shown, on the sliding surface 11, in addition to the first dynamic pressure generation region 45, a second dynamic pressure generation region 55 is also formed. The first dynamic pressure generation region 45 is composed of a plurality of spiral grooves 46 formed between the extension portions 14c of the second dynamic pressure generation groove 14. The second dynamic pressure generation region 55 is composed of a plurality of minute recesses, namely annular grooves 56, provided closer to the fluid to be sealed side than the terminal 14b of the second dynamic pressure generation groove 14. Accordingly, by superimposing the dynamic pressure effect generated by the first dynamic pressure generation region 45 and the dynamic pressure effect generated by the second dynamic pressure generation region 55, the foreign matter discharge performance can be further improved. In addition, the sealing performance at rest can be improved by the annular grooves 56.

[0066] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific structure is not limited to these embodiments, and even if there are changes or additions within the scope not departing from the gist of the present invention, they are all included in the present invention.

[0067] For example, in the above Examples 1 to 8, a mechanical seal for an automobile has been described as an example of the sliding member, but other mechanical seals such as those for general industrial machinery can also be used. Moreover, not limited to mechanical seals, sliding members other than mechanical seals such as sliding bearings can also be used.

[0068] In addition, in the above Examples 1 to 8, the first and second dynamic pressure generation grooves and the minute recesses are described by taking the stationary seal ring as an example, but the first and second dynamic pressure generation grooves and the minute recesses can also be provided on the rotating seal ring, and minute recesses can also be provided on both surfaces of the stationary seal ring and the rotating seal ring.

[0069] In addition, in the above-described Embodiments 1 to 8, the description has been made with the fluid side to be sealed as the high-pressure side and the leakage side as the low-pressure side. However, it is also possible that the fluid side to be sealed is the low-pressure side, the leakage side is the high-pressure side, or the pressures of the fluid side to be sealed and the leakage side are substantially the same.

[0070] In addition, in the above-described Embodiments 1 to 8, an example of the built-in type of the mechanical seal having a sliding member has been described. However, it can also be applied to the external type for sealing a fluid having a leakage tendency from the inner diameter side toward the outer diameter side of the sliding surface. For example, Figure 13 A modified example in which the components of Embodiment 1 are made into the external type is shown.

[0071] In addition, in the above-described Embodiments 1 to 8, the case where the first and second hydrodynamic generation grooves 13 and 14 communicate with the leakage space has been described. However, it is not limited thereto, and as long as hydrodynamic pressure can be generated, they do not have to communicate.

[0072] In addition, in the above-described Embodiments 1 to 8, an example in which a plurality of second hydrodynamic generation grooves 14 are provided in the circumferential direction has been described. However, at least one groove may be provided.

[0073] In addition, in the above-described Embodiments 1 to 8, the micro recesses have been exemplified by the groove shape. However, it is not limited to the groove shape. For example, it may be a dimple. In addition, in the case of a dimple, a part thereof may be opened in a semi-circular shape at the edge portion on the fluid side to be sealed.

[0074] In addition, the micro recesses constituting the first and second hydrodynamic generation regions refer to recesses having a depth of less than one-half, a width of less than one-fifth, and a volume of less than one-tenth of those of the first and second hydrodynamic generation grooves 13 and 14. Within this range, the shape is not limited. [[ID=}18]

[0075] In the above-described Embodiments 5 and 6, the micro recesses constituting the first hydrodynamic generation region formed between the terminals 14b of the second hydrodynamic generation groove 14 extend to a position closer to the fluid side to be sealed than the terminals 14b of the second hydrodynamic generation groove 14 and also constitute the second hydrodynamic generation region. However, it is not limited thereto, and micro recesses having the same shape may be separated in the radial direction to respectively constitute the first and second hydrodynamic generation regions.

[0076] In addition, in the above-described Embodiments 1 to 8, the description has been made by taking the case where the first hydrodynamic generation groove has the same shape, that is, the radial position of the terminal is fixed, as an example. However, it is not limited thereto. For example, a plurality of first hydrodynamic generation grooves having different radial positions of the terminals, that is, different shapes, may be formed as long as the terminals of these grooves are located at positions closer to the leakage side than the radial position of the terminal of the second hydrodynamic generation groove.

Description of Reference Numerals

[0077] 10 Stationary seal ring; 11, 21 Sliding surfaces; 13 Hydrodynamic pressure generating groove (first hydrodynamic pressure generating groove); 14 Hydrodynamic pressure generating groove (second hydrodynamic pressure generating groove); 14c Extension portion; 15 First hydrodynamic pressure generating region; 16 Arc groove (minute recess); 20 Rotating seal ring; 35 First hydrodynamic pressure generating region; 36 Radial groove (minute recess); 45 First hydrodynamic pressure generating region; 46 Helical groove (minute recess); 55 Second hydrodynamic pressure generating region; 56 Annular groove (minute recess); 66 Radial groove (minute recess); 67 Radial groove (minute recess); 76 Helical groove (minute recess); 77 Helical groove (minute recess); S1 Space on the leakage side; S2 Space on the fluid side to be sealed.

Claims

1. A sliding member, wherein the sliding surfaces of a pair of sliding rings of the sliding member rotate relative to each other, partitioning a space on the fluid side to be sealed and a space on the leakage side, where a first dynamic pressure generating groove and a second dynamic pressure generating groove are formed on at least one of the sliding surfaces. The first dynamic pressure generating groove communicates with the space on the leakage side, and the terminal position of the second dynamic pressure generating groove on the fluid side to be sealed is closer to the fluid side to be sealed than the terminal position of the first dynamic pressure generating groove on the fluid side to be sealed. And the second dynamic pressure generating groove has an extension portion that protrudes from the terminal portion of the first dynamic pressure generating groove toward the fluid side to be sealed. Between the extension portions of the second dynamic pressure generating grooves adjacent in the circumferential direction, a first dynamic pressure generating region composed of a plurality of minute recesses is formed on the fluid side to be sealed. These minute recesses do not communicate with either the space on the fluid side to be sealed or the space on the leakage side.

2. The sliding member according to claim 1, wherein the narrower width of the minute recesses is formed to be narrower than the narrower width of the dynamic pressure generating grooves.

3. A sliding member according to claim 1, wherein a second dynamic pressure generating region composed of a plurality of minute recesses is formed closer to the fluid side to be sealed than the terminal of the second dynamic pressure generating groove. These minute recesses do not communicate with either the space on the fluid side to be sealed or the space on the leakage side.

4. The sliding member according to claim 3, wherein the minute recesses constituting the first dynamic pressure generating region formed between the extension portions of the second dynamic pressure generating grooves adjacent in the circumferential direction have the same shape as the minute recesses constituting the second dynamic pressure generating region formed closer to the fluid side to be sealed than the terminal of the second dynamic pressure generating groove.

5. The sliding member according to claim 3, wherein a circular ring-shaped minute recess is formed closest to the fluid side to be sealed in the second dynamic pressure generating region.

6. The sliding member according to any one of claims 1 to 5, wherein the minute recesses constituting the first dynamic pressure generating region formed between the extension portions of the second dynamic pressure generating grooves adjacent in the circumferential direction are formed along the rotation direction of the opposing sliding surfaces.

7. The sliding member according to any one of claims 1 to 3, wherein the minute recesses constituting the first dynamic pressure generating region formed between the extension portions of the second dynamic pressure generating grooves adjacent in the circumferential direction have a radial component.

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