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 (13). Furthermore, 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. Table surfaces (19) are formed between the extension parts (14c) of the second dynamic pressure generating grooves (14) adjacent to each other in the circumferential direction. A dynamic pressure generation region (15) comprising a plurality of minute recesses (16) that do not communicate with both the space (S2) on the fluid side to be sealed and the space (S1) on the leakage side is formed at a position closer to the fluid side to be sealed than the terminal ends (14b) of the second dynamic pressure generation grooves (14) adjacent in the circumferential direction.

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 field 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 includes 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 loss 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 is used to separate the two sliding surfaces from each other and form a gas film therebetween, thereby achieving low friction.

[0004] In addition, the hydrodynamic pressure generating groove that uses a gas in this spiral shape to generate hydrodynamic pressure has a function of discharging foreign matter in the hydrodynamic pressure generating groove to the outside of the sliding surface by using the gas inhaled from one end side in the radial direction during high-speed rotation. However, since the plurality of hydrodynamic pressure generating grooves in Patent Document 1 all 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] Then, 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 Application 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] Although during high-speed rotation, the hydrodynamic pressure generating grooves can significantly increase the pressure on the terminal side and effectively discharge foreign matters through the shearing action between the opposed sliding surfaces, during low-speed rotation, the pressure on the terminal side decreases, and thus there is a problem that it is difficult to fully exhibit the foreign matter discharging effect.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide a sliding member that can exhibit a sufficient foreign matter discharging effect regardless of whether it is rotating at high speed or low speed.

[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 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 in at least one of the 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; a land is formed between the extension portions of the second hydrodynamic pressure generating grooves adjacent in the circumferential direction; a hydrodynamic pressure generating region composed of a plurality of minute recesses is formed at a position closer to the sealed fluid side than the terminals of the second hydrodynamic pressure generating grooves adjacent in the circumferential direction, and the minute recesses do not communicate with either the space on the sealed fluid side or the space on the leakage side. Accordingly, by the minute recesses formed on the space side closer to the sealed fluid side than the first and second hydrodynamic pressure generating grooves, hydrodynamic pressure is generated in the hydrodynamic pressure generating region composed of the minute recesses, and the formation of the fluid film can be maintained and supplemented from the beginning of low-speed rotation, and the interface between the fluid on the leakage side and the sealed fluid can be pressed toward the sealed fluid side. In addition, since there are minute recesses at a position closer to the sealed fluid side than the second hydrodynamic pressure generating grooves, and a land exists between the circumferences of the portions of the second hydrodynamic pressure generating grooves protruding toward the sealed fluid side, the hydrodynamic pressure effect of the first hydrodynamic pressure generating groove can be improved, and since the minute recesses can assist the hydrodynamic pressure effect of the second hydrodynamic pressure generating groove, the discharge performance of liquids, foreign matters, etc. can be improved even during low-speed rotation.

[0010] The width of the narrower part of the minute recesses can be formed to be narrower than the width of the narrower part of the hydrodynamic pressure generating grooves. Accordingly, since the width of the micro recess is narrower than that of both the first hydrodynamic pressure generating groove and the second hydrodynamic pressure generating groove, a table surface can be ensured at a position closer to the fluid to be sealed than the terminals of the first hydrodynamic pressure generating groove and the second hydrodynamic pressure generating groove. While preventing the leakage of the fluid to be sealed, the hydrodynamic pressure generating effect brought by the micro recess during low-speed rotation can be obtained.

[0011] At least a part of the micro recess may be formed along the rotation direction of the opposed sliding surfaces. Accordingly, since there is no radial component in the micro recess, the sealing performance at rest is improved; and for the fluid flowing out from the first hydrodynamic pressure generating groove to the fluid to be sealed side, the micro recess will become a resistance, thereby generating hydrodynamic pressure, which can effectively assist the hydrodynamic pressure generating effect during low-speed rotation.

[0012] At least a part of the micro recess may also have a radial component. Accordingly, a flow of the radial component is generated in the micro recess, thereby further improving the foreign matter discharge property.

[0013] In the hydrodynamic pressure generating region, the micro recess closest to the fluid to be sealed side may be annular. Thereby, leakage of the fluid to be sealed into the space on the leakage side can be prevented.

[0014] All of the micro recesses constituting the hydrodynamic pressure generating region may have the same shape. Accordingly, by keeping the flow direction of the fluid guided by the micro recess constant, turbulence can be suppressed and the hydrodynamic pressure generating effect can be stabilized.

[0015] In addition, the fluid to be sealed may be a gas, a liquid, or a mist-like fluid mixed with a gas and a liquid. Advantages of the Invention Brief Description of the Drawings 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 3 is an enlarged view of the sliding surface of the stationary seal ring in Embodiment 1 as observed axially. Figure 4 is an explanatory view of the flow of the fluid in the first and second hydrodynamic pressure generating grooves and the micro recess as observed axially for the sliding surface of the stationary seal ring in Embodiment 1 during high-speed rotation. Figure 5 is an explanatory view of the flow of the fluid in the first and second hydrodynamic pressure generating grooves and the micro recess as observed axially for the sliding surface of the stationary seal ring in Embodiment 1 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 a view of the sliding surface of the stationary seal ring in the externally mounted modification as observed axially. Detailed Embodiments

[0017] Hereinafter, the embodiments of the sliding member of the present invention will be described according to the embodiments. Embodiment 1

[0018] The following refers to Figures 1 to 5 The sliding member according to this Embodiment 1 will be described. In this embodiment, the sliding member is taken as an example in the form of a mechanical seal. In addition, the internal space of the mechanical seal is a space S1 in which the atmosphere A exists (hereinafter simply referred to as "the space on the leakage side"). In addition, the external space of the mechanical seal is a space S2 in which the fluid F to be sealed exists (hereinafter simply referred to as "the space on the fluid-to-be-sealed side"). In addition, 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.

[0019] Figure 1 The mechanical seal for an automobile shown is an internally mounted (inside) seal for sealing the fluid F to be sealed that has a tendency to leak from the outer diameter side to the inner diameter side of the sliding surface, and the space S1 on the leakage side communicates with the atmosphere A. In addition, in this embodiment, the fluid F to be sealed is taken as an example in the form of a high-pressure liquid, and the atmosphere A is taken as a gas having a lower pressure than the fluid F to be sealed. In addition, the fluid F to be sealed is not limited to a liquid, and may also be a gas or a mist-like fluid in which a gas and a liquid are mixed. The fluid in the space S1 on the leakage side is not limited to a gas, and may also be a liquid or a mist-like fluid in which a gas and a liquid are mixed.

[0020] The mechanical seal mainly consists of a rotating seal ring 20, which is a circular ring-shaped other sliding member, and a stationary seal ring 10, which is 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 equipment to be installed 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 with each other and slide. 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.

[0021] The stationary seal ring 10 and the rotating seal ring 20 are typically formed of two SiCs (hard materials), or formed of a combination of SiC (hard material) and carbon (soft material), but are not limited thereto, and 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-mentioned sliding materials can also be used.

[0022] As Figure 2 with Figure 3 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 used as the forward rotation direction, and the rotation direction shown by the dotted-line arrow will be used as the reverse rotation direction for explanation.

[0023] 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 the radial terminals 13b and 14b are formed. In contrast, the start end 13a of the first dynamic pressure generating groove 13 with a shorter radial length communicates with the space S1 on the leakage side, and its terminal 13b does not communicate with 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 longer radial length communicates with the space S1 on the leakage side, and its terminal 14b does not communicate with the space S2 on the fluid side to be sealed.

[0024] The second dynamic pressure generating grooves 14 are equally spaced in the circumferential direction of 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 this 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.

[0025] 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.

[0026] The first dynamic pressure generating groove 13 has its starting end 13a communicating with the space S1 on the leakage side. The first dynamic pressure generating groove 13 inclines from the starting end 13a toward the outer diameter side in the forward rotation direction of the rotary seal ring 20 (the forward rotation direction of relative rotation) and extends in an arc shape, and is a spiral groove that generates dynamic pressure at the terminal end 13b when the rotary seal ring 20 rotates forward. Similarly, the starting end 14a of the second dynamic pressure generating groove 14 communicates with the space S1 on the leakage side. The second dynamic pressure generating groove 14 extends from the starting 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 end 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 inclining and extending in an arc shape in the forward rotation direction of the rotary seal ring 20. For example, they may also incline and extend in a straight line shape in the forward rotation direction of the rotary seal ring 20 (the forward rotation direction of relative rotation).

[0027] As Figure 3 shown, the terminal end 13b of the first dynamic pressure generating groove 13 is located closer to the leakage side than the terminal end 14b of the second dynamic pressure generating groove 14. That is, the second dynamic pressure generating groove 14 is formed with an extension portion 14c that extends longer in the radial direction toward the fluid to be sealed side than the first dynamic pressure generating groove 13.

[0028] At a position closer to the fluid to be sealed side than the terminal end 14b of the second dynamic pressure generating groove 14, an annular groove 16 serving as a minute recess is formed. The region formed by these multiple annular grooves 16 is called the dynamic pressure generating region 15. Specifically, in this embodiment, the dynamic pressure generating region 15 is composed of multiple annular grooves 16 formed in parallel and separated at a specified interval in the radial direction of the sliding surface 11.

[0029] The annular groove 16 is not in communication with the space S1 on the leakage side and the space S2 on the fluid side to be sealed, and is also not in communication with the first and second hydrodynamic pressure generating grooves 13, 14. The annular groove 16 is in the shape of a ring along the relative rotation direction of the sliding surface 21 of the opposed rotary seal ring 20.

[0030] In addition, the depth of each annular groove 16 is formed to be below the depth of the first and second hydrodynamic pressure generating grooves 13, 14. Further, the narrower radial width among the circumferential width and the radial width of each annular groove 16 is narrower than the narrower circumferential width among the widths of the first and second hydrodynamic pressure generating grooves 13, 14. Also, the volume of each annular groove 16 is smaller than that of the first and second hydrodynamic pressure generating grooves 13, 14. Preferably, the depth of each annular groove 16 is 1 / 2 or less of that of the first and second hydrodynamic pressure generating grooves 13, 14, the width is 1 / 5 or less of that thereof, and the volume is 1 / 10 or less of that thereof.

[0031] In addition, the sliding surface 11 has table surfaces 17, 18, 19, 23 on the same plane. The table surface 17 is the portion between the first hydrodynamic pressure generating groove 13 and the second hydrodynamic pressure generating groove 14 in the circumferential direction. The table surface 18 is the portion between the annular grooves. The table surface 19 is the portion between the extended portions 14c of two adjacent second hydrodynamic pressure generating grooves 14 in the circumferential direction; the table surface 23 is the portion closer to the fluid side to be sealed than the annular groove 16.

[0032] Next, use Figure 4 and Figure 5 to describe the operation when the stationary seal ring 10 and the rotary seal ring 20 rotate relative to each other. In addition, in the present embodiment, the description will be made in the order of when the rotary seal ring 20 stops, rotates at a low speed, and rotates at a high speed.

[0033] First, when the rotary seal ring 20 is not rotating and stopped, the gas in the space S1 on the leakage side flows into the first hydrodynamic pressure generating groove 13 from the starting end 13a. In addition, similarly, the gas in the space S1 on the leakage side flows into the second hydrodynamic pressure generating groove 14 from the starting end 14a. The stationary seal ring 10 is biased toward the rotary seal ring 20 by the elastic member 7. The sliding surfaces 11, 21 are in contact with each other. By retaining the table surface 23 in a circular shape closer to the fluid side to be sealed than the annular groove 16, leakage of the fluid F in the space S2 on the fluid side to be sealed into the space S1 on the leakage side is prevented. In addition, since there is no radial component in the annular groove 16, the plurality of annular grooves 16 arranged in a row in the radial direction function as a labyrinth seal, improving the sealing performance at rest.

[0034] Next, the state during high-speed rotation when the rotary seal ring 20 rotates at a high speed in the forward rotation direction with respect to the stationary seal ring 10, such as in a stable operation or the like, will be described. As Figure 4As shown, during high-speed rotation, the gas in the first dynamic pressure generating groove 13 moves along with the rotation of the rotary seal ring 20 in the rotation direction by means of the shearing action between the sliding surface 21, and then moves towards the terminal 13b. Similarly, the gas in the second dynamic pressure generating groove 14 moves along with the rotation of the rotary seal ring 20 in the rotation direction by means of the shearing action between the sliding surface 21, and then moves towards the terminal 14b.

[0035] Accordingly, dynamic pressure is generated at the terminal 13b of the first dynamic pressure generating groove 13 and its vicinity, and at the terminal 14b of the second dynamic pressure generating groove 14 and its vicinity. This dynamic pressure separates the sliding surfaces 11 and 21 from each other, and uses the fluid on the leakage side, i.e., 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 start ends 13a and 14a, the gas is sucked into the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 from the start ends 13a and 14a.

[0036] In addition, the dynamic pressure generated at the terminal 13b of the first dynamic pressure generating groove 13 and its vicinity, and the dynamic pressure generated at the terminal 14b of the second dynamic pressure generating groove 14 and its vicinity can effectively discharge foreign matters and the sealed fluid F between the sliding surfaces 11 and 21 to the outside of the sliding surfaces 11 and 21.

[0037] Specifically, dynamic pressure is generated at the terminal 13b of the first dynamic pressure generating groove 13 with a larger number of configurations than 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 further towards 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 of the sliding surfaces 11 and 21, that is, the space S2 that is easily discharged towards the sealed fluid side. In addition, an annular groove 16 exists at a position closer to the sealed fluid side than the second dynamic pressure generating groove 14, and a table surface 19 exists between the circumferences of the extension portion 14c that protrudes towards the sealed fluid side of the adjacent second dynamic pressure generating groove 14. The dynamic pressure effect of the first dynamic pressure generating groove 13 is increased by the table surface 19, and the dynamic pressure effect of the second dynamic pressure generating groove 14 is assisted by the annular groove 16, so that the discharge performance of discharging liquid and foreign matters can be improved even during low-speed rotation.

[0038] 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 fluid to be sealed side than the terminals 13b and 14b of the first and second dynamic pressure generating grooves 13 and 14, so as to maintain the effect of preventing the fluid F to be sealed from leaking.

[0039] Next, the situation at the time 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 at low-speed rotation, the gas in the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 moves along with 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 will rise at the terminals 13b and 14b respectively, and dynamic pressure will be generated at the terminals 13b and 14b and in their vicinity. However, the dynamic pressure effect at low-speed rotation is lower than that at high-speed rotation.

[0040] Similarly, the gas in the annular groove 16 moves along with the rotation direction of the rotary seal ring 20 through the shearing action with the sliding surface 21, so as to move in the circumferential direction, causing the internal pressure to rise and generating dynamic pressure toward the outside of the annular groove 16. Through this dynamic pressure, the sliding surface 21 of the rotary seal ring 20 facing it is pushed.

[0041] In addition, as Figure 5 shown, for the fluid flowing out from the first dynamic pressure generating groove 13 to the leakage side, the annular groove 16 constitutes a resistance. Thereby, dynamic pressure as shown by the white arrow is generated, effectively assisting the dynamic pressure generation effect at low-speed rotation. Specifically, a part of the fluid flowing out from the first dynamic pressure generating groove 13 flows into the side part of the annular groove 16. The radial flow of the fluid flowing out from the first dynamic pressure generating groove 13 can generate dynamic pressure in the annular groove 16 from the side part on the fluid-to-be-sealed side to between the sliding surfaces 11 and 12. That is, the fluid flowing slightly toward the outer diameter side from the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14 also generates dynamic pressure when crossing the annular groove 16.

[0042] Since the volume of the annular groove 16 is smaller than that of the first and second dynamic pressure generating grooves 13 and 14, auxiliary dynamic pressure that slightly separates the sliding surfaces 11 and 21 from each other can be generated even when the rotary seal ring 20 is rotating at low speed. In other words, the annular groove 16 can be said to play a role in assisting the generation of dynamic pressure for the first dynamic pressure generating groove 13 and the second dynamic pressure generating groove 14.

[0043] The hydrodynamic pressure generation region 15 composed of a plurality of annular grooves 16 is located closer to the fluid to be sealed side than the end 14b of the second hydrodynamic pressure generation groove 14. Thus, the hydrodynamic pressure generated on the fluid to be sealed side between the sliding surfaces 11 and 21 can separate the sliding surfaces 11 and 21, and at the same time effectively discharge foreign matters from between the sliding surfaces 11 and 21, that is, it is easy to discharge them into the space S2 on the fluid to be sealed side. In addition, the annular grooves 16 are formed only at the minimum and necessary positions on the sliding surface 11. Therefore, the table surface on the sliding surface 11 is ensured, and thus the influence on the sealing performance during high-speed rotation can be prevented.

[0044] In this way, by quickly discharging the foreign matters that will cause resistance to rotation at an early stage before reaching high-speed rotation, good relative rotation can be achieved between the sliding surfaces 11 and 21. Moreover, during low-speed rotation, the interface between the leakage-side fluid and the fluid to be sealed F is pushed to a position closer to the fluid to be sealed side than the end 14b of the second hydrodynamic pressure generation groove 14, so that while improving the foreign matter discharge effect, the leakage of the fluid to be sealed F can be suppressed.

[0045] Compared with the first hydrodynamic pressure generation groove 13, the second hydrodynamic pressure generation groove 14 extends longer in the radial direction. Thus, especially during low-speed rotation, the pressure at the end 14b and its vicinity is lower than that of the first hydrodynamic pressure generation groove 13, that is, there is a tendency that it is difficult to fully obtain the hydrodynamic pressure generation effect. The annular groove 16 is located closer to the fluid to be sealed side than the end 13b of the first hydrodynamic pressure generation groove 13 and generates hydrodynamic pressure at this position. That is, in addition to the hydrodynamic pressure generated at the end 13b of the first hydrodynamic pressure generation groove 13, hydrodynamic pressure is also generated at the annular groove 16, so that a higher foreign matter discharge effect can be achieved. In other words, the hydrodynamic pressure generation effect can be complemented by the annular groove 16 during low-speed rotation.

[0046] In addition, the hydrodynamic pressure generated by the annular groove 16 can assist in forming a fluid film during low-speed rotation. Thus, the formation of the fluid film can be maintained and complemented from the initial stage of low-speed rotation, and the wear between the sliding surfaces 11 and 21 can be suppressed. In addition, by quickly discharging the foreign matters that become the rotation resistance during the initial operation, the slidability during subsequent low-speed rotation can be improved.

[0047] In addition, the annular groove 16 is formed along the rotation direction of the opposing sliding surface 21. Since there is no radial component, the sealing performance at rest can be improved.

[0048] Moreover, the annular groove 16 extends continuously in the circumferential direction. Therefore, at rest, the entry of the fluid to be sealed F in the circumferential direction toward the leakage-side space S1 can be suppressed, thereby improving the sealing performance. Embodiment 2

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

[0050] The hydrodynamic pressure generation region 35 of this embodiment is composed of a plurality of radial grooves 36, which are 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. In the radial grooves 36, since a flow in the radial component is generated, the foreign matter discharge performance is 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.

[0051] As shown in this embodiment, the radial grooves 36 are preferably not in communication with the space S2 on the fluid side to be sealed, but may also be in communication. Embodiment 3

[0052] Next, refer to Figure 7 The relevant content related to the sliding component involved in Embodiment 3 will be described. In addition, the description of the same configuration as in Embodiment 1 will be omitted.

[0053] The hydrodynamic pressure generation region 45 in this embodiment is composed of a plurality of spiral grooves 46, which are minute recesses that are inclined in the forward rotation direction of the rotary seal ring 20 and extend 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. In addition, flows in the radial and circumferential components are 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 at extremely low relative rotation speeds. Embodiment 4

[0054] Next, refer to Figure 8 The relevant content related to the sliding component involved in Embodiment 4 will be described. In addition, the description of the same configuration as in Embodiment 1 will be omitted.

[0055] As Figure 8As shown, a plurality of minute recess groups 550 are provided on the sliding surface 11 and are circumferentially distributed. Each minute recess group 550 is composed of a plurality of arc grooves 56 as minute recesses arranged radially. The arc grooves 56 are formed in an annular shape along the relative rotation direction, which is the relative rotation direction between it and the sliding surface 21 of the opposed rotary seal ring 20. The minute recess groups 550 adjacent to each other in the circumferential direction are spaced apart from each other by a prescribed distance. Each minute recess group 550 constitutes a hydrodynamic pressure generation region. Accordingly, by the rotation of the opposed rotary seal ring 20, hydrodynamic pressure can be effectively generated at the respective terminals 56b of the arc grooves 56 constituting the minute recess group 550 and in the vicinity thereof, thereby improving the foreign matter discharge performance and the hydrodynamic pressure generation effect. In addition, by the arc grooves 56 along the rotation direction of the rotary seal ring 20, leakage of the fluid to be sealed can be suppressed. Example 5

[0056] Next, with reference to Figure 9 the relevant content of the sliding member related to Example 5 will be described. In addition, the description of the same configuration as that in the above-described Example 1 will be omitted.

[0057] As Figure 9 shown, on the sliding surface 11, the hydrodynamic pressure generation region 65 is composed of an annular minute recess group 660 and an annular groove 66. The minute recess group 660 is composed of a plurality of radial grooves 36 extending radially. The radial grooves 36 are minute recesses and are formed in a plurality in the circumferential direction. The annular groove 66 is a minute recess provided closer to the fluid to be sealed side than the minute recess group 660. Accordingly, in addition to improving the foreign matter discharge performance by the flow of the radial component generated by the radial grooves 36, the sealing performance at rest can also be improved by the annular groove 66. Example 6

[0058] 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 that in the above-described Example 1 will be omitted.

[0059] As Figure 10 shown, on the sliding surface 11, the hydrodynamic pressure generation region 75 is composed of an annular minute recess group 760 and an annular groove 66. The minute recess group 760 is composed of a plurality of spiral grooves 46 that are inclined in the positive rotation direction of the rotary seal ring 20 and extend in an arc shape. The spiral grooves 46 are minute recesses and are formed in a plurality in the circumferential direction. The annular groove 66 is a minute recess provided closer to the fluid to be sealed side than the minute recess group 760. Accordingly, in addition to improving the foreign matter discharge performance by the flow of the circumferential component and the radial component generated in the spiral grooves 46, the sealing performance at rest can also be improved by the annular groove 66.

[0060] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the specific configurations are not limited to these examples, and any modifications or additions within the scope not departing from the gist of the present invention are included in the present invention.

[0061] For example, in Embodiments 1 to 6, a mechanical seal as a sliding member is used for an automobile for illustration, but it can also be applied to other types of mechanical seals such as general industrial machinery. In addition, not only limited to mechanical seals, it can also be used for sliding members other than mechanical seals such as sliding bearings.

[0062] In addition, in Embodiments 1 to 6 described above, an example of providing a hydrodynamic pressure generating groove and minute recesses in the stationary seal ring has been illustrated. However, the hydrodynamic pressure generating groove and minute recesses can also be provided in the rotating seal ring, and minute recesses can also be provided on both surfaces of the stationary seal ring and the rotating seal ring.

[0063] In addition, in Embodiments 1 to 6 described above, 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 can also be the case where the fluid side to be sealed is the low-pressure side and the leakage side is the high-pressure side, or the pressures of the fluid side to be sealed and the leakage side can be made substantially the same.

[0064] In addition, in Embodiments 1 to 6 described above, the inside type of a mechanical seal having a sliding member has been illustrated as an example. However, it can also be applied to the outside type for sealing a fluid having a tendency to leak from the inner diameter side toward the outer diameter side of the sliding surface. For example, a modified example of modifying the structure of Embodiment 1 to the inside type is shown in Figure 11 .

[0065] In addition, in Embodiments 1 to 6 described above, the case where the hydrodynamic pressure generating groove communicates with the leakage space has been illustrated, but it is not limited thereto, and as long as hydrodynamic pressure can be generated, it can also be non-communicating.

[0066] In addition, in Embodiments 1 to 6 described above, the form of providing a plurality of second hydrodynamic pressure generating grooves 14 in the circumferential direction has been illustrated as an example, and at least one can be provided.

[0067] In addition, in Embodiments 1 to 6 described above, the minute recesses have been illustrated by way of example in the shape of a groove, but it is not limited to the groove shape. For example, it can be a dimple. In addition, in the case of a dimple, a part thereof can be opened in a semicircular shape at the edge portion on the fluid side to be sealed.

[0068] In addition, the minute recesses constituting the hydrodynamic pressure generating region 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 with respect to the first and second hydrodynamic pressure generating grooves 13 and 14. Within this range, the shape is not limited. [Description of Reference Numerals]

[0069] 10 Stationary sealing ring; 11, 21 Sliding surfaces; 13 Dynamic pressure generating groove (first dynamic pressure generating groove); 14 Dynamic pressure generating groove (second dynamic pressure generating groove); 14c extension; 15 Dynamic pressure generating area; 16 Annular groove (micro-recess); 20 Rotating sealing ring; 35 Dynamic pressure generating area; 36 Radial groove (micro-recess); 45 Dynamic pressure generating area; 46 Spiral groove (micro-recess); 55 Dynamic pressure generating area; 56 Circular arc groove (micro-recess); 65 Dynamic pressure generating area; 66 Annular groove (micro-recess); 75 Dynamic pressure generating area; S1 Space on the leakage side; S2 Space on the sealed fluid side.

Claims

1. A sliding member, in which 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 dynamic pressure generating groove and a second dynamic pressure generating groove are formed in at least one of the sliding surfaces, the first dynamic pressure generating groove communicates with the space on the leakage side, a terminal position of the second dynamic pressure generating groove on the sealed fluid side is located closer to the sealed fluid side than a terminal position of the first dynamic pressure generating groove on the sealed fluid side, 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 sealed fluid side; a mesa is formed between the extension portions of the second dynamic pressure generating grooves adjacent in the circumferential direction; a dynamic pressure generating region composed of a plurality of minute recesses is formed at a position closer to the sealed fluid side than the terminals of the second dynamic pressure generating grooves adjacent in the circumferential direction, and the minute recesses do not communicate with either the space on the sealed fluid side or the space on the leakage side.

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

3. The sliding member according to claim 1, wherein, at least a part of the minute recesses is formed along a rotation direction of the opposed sliding surfaces.

4. The sliding member according to claim 1, wherein, at least a part of the minute recesses has a radial component.

5. The sliding member according to claim 1, wherein, in the dynamic pressure generating region, the minute recess closest to the sealed fluid side is annular.

6. The sliding member according to any one of claims 1 to 4, wherein, the minute recesses constituting the dynamic pressure generating region are all of the same shape.

Images