Sliding parts

Abstract

To provide sliding parts that can slide smoothly while suppressing fluid leakage even in low-pressure environments. [Solution] A pair of sliding members 10 and 20 are arranged at a point where they rotate relative to each other, and the sliding surfaces 11 and 21 of each sliding member 10 and 20 slide relative to each other, forming a sliding component that partitions a sealed fluid space S1 and a low-pressure space S2 which has a lower pressure than the sealed fluid space S1. The sliding surface 11 has a first groove 14 that communicates with the sealed fluid space S1, a dynamic pressure generating groove 13 located between the sealed fluid space S1 and the first groove 14, and a second groove 15 that extends from the low-pressure space S2 side toward the first groove 14 side.

Description

Technical Field

[0001] The present invention relates to sliding parts that rotate relative to each other, and is used for sliding parts used in a shaft sealing device that seals the rotating shaft of a rotating machine in, for example, the automotive, general industrial machinery, or other sealing fields, or sliding parts used in bearings of machines in the automotive, general industrial machinery, or other bearing fields.

Background Art

[0002] As a sliding part for preventing leakage of a sealed fluid around a rotating shaft in a rotating machine, for example, a mechanical seal composed of a pair of annular sliding rings that rotate relative to each other and whose sliding surfaces slide against each other is known.

[0003] For example, in the mechanical seal shown in Patent Document 1, sliding members are provided on each of the driven ring and the seat ring. The sliding member is formed in an annular thin plate shape, and a metal film is plated on its surface. The metal film formed in this way not only has excellent wear resistance but also can make the thickness substantially uniform, so that the friction generated when the metal films slide against each other can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The mechanical seal such as that in Patent Document 1 is excellent in wear resistance and friction reduction effect in a non-lubricated state, and thus can be used in a low-pressure environment such as a vacuum. However, since a fluid is not used as a lubricating medium, there is a limit to reducing sliding resistance, and long-term use has been difficult.

[0006] This invention addresses these problems and aims to provide a sliding component that can slide smoothly while suppressing fluid leakage even in a low-pressure environment. [Means for solving the problem]

[0007] To solve the aforementioned problems, the sliding component of the present invention is A sliding component comprising a pair of sliding members arranged at a location where they rotate relative to each other, wherein the sliding surfaces of each sliding member slide relative to each other, thereby dividing a sealed fluid space from a low-pressure space at a lower pressure than the sealed fluid space, At least one of the sliding surfaces has a first groove communicating with the sealed fluid space, a dynamic pressure generating groove located between the sealed fluid space and the first groove, and a second groove extending from the low-pressure space side toward the first groove side. According to this design, the land surrounded by the first groove can be smoothly slid by the sealed fluid supplied from the dynamic pressure generating groove, and the sealed fluid that has moved to the lower pressure side of the first groove can be returned to the first groove by the second groove. As a result, even in a low-pressure environment, the sliding parts can be smoothly slid while suppressing leakage of the sealed fluid.

[0008] The second groove may be in communication with the low-pressure space. According to this, the gap between the sliding surfaces can be appropriately maintained, and a balance can be maintained between the shear force acting on the sealed fluid in the second groove and the suction force on the low-pressure space side.

[0009] The second groove may have a low-pressure space side extension that extends circumferentially along the edge of the sliding surface on the low-pressure space side. According to this method, the sealed fluid can be recovered over a wide area in the radial direction.

[0010] The tip of the second groove on the first groove side may be provided upstream of the downstream extension that extends radially downstream in the relative rotational direction of the first groove. This makes it easier to efficiently flow the recovered sealed fluid into the first groove.

[0011] The second groove may be positioned entirely on the low-pressure side of the first groove. According to this, the sealed fluid that has moved to the low-pressure space side of the first groove can be smoothly flowed into the first groove.

[0012] The dynamic pressure generating groove is a Rayleigh step connected to the first groove, The circumferential length of the Rayleigh step may be less than or equal to half the circumferential length of the land enclosed by the first groove. According to this, the fluid to be sealed can be kept on the land surrounded by the first groove for a longer period, allowing for more stable and smoother sliding.

[0013] The dynamic pressure generating groove, the first groove, and the second groove may be provided in multiple locations spaced apart in the circumferential direction. According to this, the sealed fluid can be recovered over a wide area in the circumferential direction while the sliding parts slide in a balanced manner.

[0014] The second groove may be positioned on the low-pressure space side of the land between adjacent first grooves in the circumferential direction, at least in part. According to this, the sealed fluid that has flowed out into the lands between adjacent first grooves in the circumferential direction can be efficiently recovered.

[0015] The dynamic pressure generating groove is provided with a groove extending at least upstream in the relative rotation direction from the sealed fluid space side or the first groove side, and a groove extending at least downstream in the relative rotation direction from the sealed fluid space side or the first groove side. The second groove may include a groove extending from the low-pressure space side at least toward the first groove side and upstream in the relative rotation direction, and a groove extending from the low-pressure space side at least toward the first groove side and downstream in the relative rotation direction. According to this, regardless of the direction of rotation, even in a low-pressure environment, the sealed fluid can be prevented from leaking while sliding smoothly.

[0016] The hydrodynamic groove is a release step connected to the first groove, an inverse release step extending towards the release step is connected to the first groove, The sum of the circumferential length of the release step and the circumferential length of the inverse release step may be not more than one half of the circumferential length of the land surrounded by the first groove. According to this, whether the relative rotation direction is forward rotation or reverse rotation, while retaining the sealed fluid on the land surrounded by the first groove for a long time, it is possible to prevent the sealed fluid on the land surrounded by the first groove from becoming excessive.

[0017] In the present invention, the low pressure means a pressure lower than the normal atmospheric pressure, and the low pressure state includes a vacuum state. The vacuum state is the state of "a space filled with a gas having a pressure lower than the normal atmospheric pressure" defined by Japanese Industrial Standards (JIS Z 8126).

Brief Description of Drawings

[0018] [Figure 1] It is a longitudinal sectional view showing an example of a mechanical seal in Example 1 according to the present invention. [Figure 2] It is a view of the sliding surface of the stationary seal ring in Example 1 as seen from the axial direction. [Figure 3] It is an enlarged view of the main part of FIG. 2. [Figure 4] (a) to (c) are diagrams for explaining Shape Examples 1-1, 1-2, and 1-3 of the hydrodynamic groove in Example 1. [Figure 5] (a) and (b) are diagrams for explaining Shape Examples 1-4 and 1-5 of the first groove in Example 1. [Figure 6] (a) to (c) are diagrams for explaining Shape Examples 1-6, 1-7, and 1-8 of the second groove in Example 1. [Figure 7] It is a view of the sliding surface of the stationary seal ring in Example 2 according to the present invention as seen from the axial direction. [Figure 8] Figure 7 is an enlarged view of the main part. [Figure 9] This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 3 of the present invention. [Figure 10] This figure illustrates the shape example 3-1 of the second groove in Example 3. [Modes for carrying out the invention]

[0019] Embodiments for implementing the sliding component according to the present invention will be described below based on examples. [Examples]

[0020] The sliding component according to Example 1 will be described with reference to Figures 1 to 6. In this example, a mechanical seal will be used as an example of a sliding component. In this mechanical seal, the sealed fluid F, such as oil, is present in the outer space S1, which is the sealed fluid space. The inner space S2, which is a low-pressure space, is a vacuum V. In other words, the mechanical seal is used in a low-pressure environment. For the sake of explanation, dots may be added to grooves and the like formed on the sliding surface in the drawings.

[0021] The mechanical seal shown in Figure 1 is an inside type that seals the fluid F to be sealed, which tends to leak from the outer diameter side to the inner diameter side of the sliding surface.

[0022] The mechanical seal mainly consists of a stationary sealing ring 10 and a rotating sealing ring 20. The stationary sealing ring 10 is annular in shape and is provided on a seal cover 5 fixed to the housing 4 of the equipment to be mounted, in a non-rotatable state and movable in the axial direction. The rotating sealing ring 20 is annular in shape and is provided on a rotating shaft 1 via a sleeve 2 so as to be rotatable with the rotating shaft 1. The stationary sealing ring 10 is biased in the axial direction by an elastic member 7. The sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 slide in close contact with each other. The sliding surface 21 of the rotating sealing ring 20 is a flat surface, and this flat surface does not have any grooves or other recesses.

[0023] The stationary sealing ring 10 and the rotating sealing ring 20 are typically formed from two SiC (hard material) components or a combination of SiC (hard material) and carbon (soft material), but are not limited to these; any sliding material used for mechanical seals is applicable. SiC can be sintered using boron, aluminum, carbon, etc., as sintering aids, or from materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC made of SiC and Si, SiC-TiC, SiC-TiN, etc. Carbon can be a mixture of carbonaceous and graphite, as well as resin-molded carbon and sintered carbon. In addition to the sliding materials mentioned above, metal materials, resin materials, surface modification materials (coating materials), and composite materials are also applicable.

[0024] As shown in Figure 2, the rotating sealing ring 20 slides relative to the stationary sealing ring 10 in a counterclockwise direction, as indicated by the solid arrow. In this embodiment, with this relative rotation direction as the reference, the clockwise side from the target position is described as the upstream side in the relative rotation direction, and the counterclockwise side from the target position is described as the downstream side in the relative rotation direction.

[0025] The sliding surface 11 of the stationary sealing ring 10 is provided with eight introduction grooves 12, eight shallow grooves 13 as dynamic pressure generating grooves, eight deep grooves 14 as first grooves, and eight recovery grooves 15 as second grooves. On the sliding surface 11, the parts other than the introduction grooves 12, shallow grooves 13, deep grooves 14, and recovery grooves 15 form flat lands.

[0026] The introduction groove 12 extends radially from the outer circumferential surface of the stationary sealing ring 10 toward the inner diameter, and is a groove with a substantially constant depth, i.e., axial length. The outer diameter end of the introduction groove 12 communicates with the outer space S1. The inner diameter end of the introduction groove 12 is closed. The eight introduction grooves 12 are equally spaced.

[0027] Furthermore, the depth of the introduction groove 12 may be shallower from the outer diameter side to the inner diameter side, for example, and the depth may vary. Also, although the cross-sectional shape of the introduction groove 12 is rectangular, it may be U-shaped, semicircular, or triangular, and may be changed as appropriate. The same applies to the other grooves 13, 14, and 15 in terms of depth and cross-sectional shape.

[0028] Furthermore, the depth of the introduction groove 12 is approximately the same as that of the deep groove 14, and shallower than that of the shallow groove 13. While the depth of the introduction groove 12 may differ from that of the deep groove 14, it is preferable that it be deeper than that of the shallow groove 13 from the viewpoint of efficiently generating dynamic pressure in the shallow groove 13.

[0029] The shallow groove 13 is a groove of constant depth that extends circumferentially from the inner diameter end of the introduction groove 12 toward the downstream side in the relative rotational direction.

[0030] The shallow groove 13 has an upstream end in the relative rotation direction that communicates with the introduction groove 12. The shallow groove 13 is closed at its downstream end 13a in the relative rotation direction. The eight shallow grooves 13 are equally spaced. In the following explanation, the upstream side in the relative rotation direction may simply be referred to as the "upstream side," and the downstream side in the relative rotation direction may simply be referred to as the "downstream side."

[0031] Each deep groove 14 is a U-shaped groove, viewed from the axial direction, that surrounds one introduction groove 12 and a shallow groove 13 that communicates with this introduction groove 12. The eight deep grooves 14 are equally spaced. Furthermore, each deep groove 14 is not connected to any of the other deep grooves 14.

[0032] More specifically, the deep groove 14 has a first inclined portion 140 as an upstream extension that extends inclined from the upstream side toward the inner diameter side and toward the downstream side, a circumferential extension portion 141 that extends along the circumferential direction toward the downstream side from the inner diameter side end of the first inclined portion 140, and a second inclined portion 142 as a downstream extension portion that extends inclined from the downstream end of the circumferential extension portion 141 toward the outer diameter side and toward the downstream side.

[0033] The first inclined portion 140 is a communication opening 140a whose outer diameter end is in communication with the outer space S1. The second inclined portion 142 is a communication opening 142a whose outer diameter end is in communication with the outer space S1.

[0034] In this embodiment, the land surrounded by one deep groove 14, that is, the land defining the introduction groove 12 and the shallow groove 13, is referred to as the first land 16. Furthermore, the land located circumferentially between adjacent deep grooves 14 in the circumferential direction, more specifically between the second inclined portion 142 in the upstream deep groove 14 and the first inclined portion 140 in the downstream deep groove 14, is referred to as the second land 17.

[0035] The recovery groove 15 is a groove formed in a Z shape when viewed from the axial direction, and as will be described in more detail later, it is located on the inner diameter side at approximately the same circumferential position as one of the deep grooves 14. Hereafter, unless otherwise specified, the deep groove 14 and the outer diameter side recovery groove 15, which are located at approximately the same circumferential position, will be described.

[0036] The depth of the recovery groove 15 is approximately the same as that of the shallow groove 13. However, the depth of the recovery groove 15 may be changed as appropriate. Because the recovery groove 15 is shallow, the sealed fluid F is less likely to be drawn into the vacuum V inner space S2 from the axial gap between the sliding surface 21 of the rotating sealing ring 20 due to its viscosity and surface tension.

[0037] More specifically, the recovery groove 15 has an inner diameter extension 150 as a low-pressure space side extension that extends in the circumferential direction, an inclined portion 151 that extends from the downstream end of the inner diameter extension 150 toward the outer diameter and downstream, and an outer diameter extension 152 that extends from the outer diameter end of the inclined portion 151 toward the downstream in the circumferential direction.

[0038] The inner diameter extension 150 extends circumferentially along the inner diameter edge 11a of the sliding surface 11. Furthermore, the inner diameter end of the inner diameter extension 150 communicates with the inner space S2 over the circumferential direction.

[0039] The inner diameter extension 150 and the inclined portion 151 are located on the inner diameter side of the second land 17. The upstream end 150a of the inner diameter extension 150 is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the second land 17.

[0040] The outer diameter extension 152 is located on the inner diameter side of the circumferential extension 141 in the deep groove 14 and extends approximately parallel to the circumferential extension 141. In other words, the outer diameter extension 152 and the circumferential extension 141 are spaced apart in the radial direction and are not in communication with each other.

[0041] In this embodiment, the land located in the region enclosed by the dashed-dotted line extending circumferentially along the inner diameter side surface of the circumferential extension portion 141 and the dashed-dotted line extending circumferentially along the outer diameter side surface of the outer diameter extension portion 152 is defined as the third land 18. This third land 18 is an annular shape that extends continuously along the circumferential direction. Note that the two dashed-dotted lines in Figure 3 are imaginary lines drawn for the sake of explanation.

[0042] Furthermore, the downstream end of the outer diameter extension 152, i.e., the tip 152a located on the outer space S1 side, has an acute angle shape that tapers toward the downstream side.

[0043] The tip 152a is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the circumferential extension portion 141. In other words, the tip 152a is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the first land 16. To put it another way, the tip 152a is located upstream of the second inclined portion 142.

[0044] In this embodiment, the land located between adjacent recovery grooves 15 in the circumferential direction is designated as the fourth land 19.

[0045] Next, the sealing between the outer space S1 and the inner space S2 by the stationary sealing ring 10 and the rotating sealing ring 20 will be explained. First, when the rotating sealing ring 20 is not rotating, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 are in surface contact. In particular, the annular third land 18 prevents the sealed fluid F from flowing out into the inner space S2.

[0046] Next, when the rotating sealing ring 20 is rotating, as shown by the thin solid arrows in Figure 3, the fluid F to be sealed in the shallow groove 13 attempts to move in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21.

[0047] The sealed fluid F is guided along the shallow groove 13 to the downstream end 13a and supplied from end 13a and its vicinity to the sliding surfaces 11 and 21, more specifically between the first land 16 and the sliding surface 21. This generates positive pressure at end 13a and its vicinity. In other words, the shallow groove 13 functions as a so-called Rayleigh step.

[0048] Furthermore, the shallow groove 13 can be adjusted by changing its depth, width, and length to control the positive pressure generated during a predetermined relative rotation.

[0049] Furthermore, by supplying the sealed fluid F between the first land 16 and the sliding surface 21, the first land 16 and the sliding surface 21 can slide smoothly against each other. In the following description, the sealed fluid F supplied between the land and the sliding surface 21 will be simply referred to as "the sealed fluid supplied to the land."

[0050] Referring to Figure 2, the circumferential length L1 from the upstream side of the introduction groove 12 to the downstream end 13a of the shallow groove 13 is approximately half the circumferential length L2 of the dynamic pressure contribution region in the first land 16 (L1 = L2 × 1 / 2). The circumferential length L2 of the dynamic pressure contribution region in the first land 16 is the sum of the circumferential length L1 and the circumferential length (L2 - L1) downstream of the shallow groove 13 in the first land 16.

[0051] In other words, the shorter the circumferential length L1 of the first land 16, the wider the area downstream of the shallow groove 13 in the first land 16 can be. The wider the area downstream of the shallow groove 13 in the first land 16, the easier it is to retain the sealed fluid F supplied to the first land 16 from the end 13a in the first land 16 for a longer period. In other words, on the sliding surface 11, since the sealed fluid F is supplied to the first land 16 from the end 13a, it is less likely to immediately flow into the deep groove 14.

[0052] This makes it easier for the stationary sealing ring 10 to maintain smooth sliding between the first land 16 and the sliding surface 21. From this viewpoint, it is preferable that the circumferential length L1 is approximately half or less of the circumferential length L2 (L1 <L2×1 / 2)。

[0053] Furthermore, a relative negative pressure is generated on the upstream side of the shallow groove 13. This negative pressure increases as it approaches the introduction groove 12. In other words, the force drawing in the sealed fluid F becomes stronger. Due to this negative pressure, the shallow groove 13 can efficiently introduce the sealed fluid F from the introduction groove 12.

[0054] Furthermore, the inlet groove 12 is deeper than the shallow groove 13 and has a larger volume, making it less likely for the sealed fluid F to be depleted. In addition, since the inlet groove 12 is in communication with the outer space S1, the sealed fluid F can flow in easily.

[0055] As a result, the fluid to be sealed F flows smoothly from the introduction groove 12 into the shallow groove 13, and the shallow groove 13 can continue to supply the fluid to be sealed F to the first land 16.

[0056] Furthermore, when the rotating sealing ring 20 is rotating, as shown by the thin solid arrows in Figure 3, the fluid F to be sealed in the deep groove 14 attempts to move in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21.

[0057] As a result, in the deep groove 14, a flow is generated in which the sealed fluid F moves in the order of the first inclined section 140, the circumferentially extended section 141, and the second inclined section 142, and flows out into the outside space S1 through the communication port 142a in the second inclined section 142. In addition, along with this flow, the sealed fluid F flows into the deep groove 14 from the outside space S1 through the communication port 140a in the first inclined section 140.

[0058] The angle θ1 formed by the first inclined portion 140 and the outer circumferential surface of the stationary sealing ring 10 on the downstream side, i.e., on the first land 16 side, is approximately 30 degrees. In other words, the first inclined portion 140 is inclined downstream from the outer diameter side toward the inner diameter side relative to the radial direction of the sliding surface 11.

[0059] As a result, when the rotating sealing ring 20 rotates relative to another, the fluid to be sealed F flows more easily from the outer space S1 into the first inclined portion 140. From this viewpoint, it is preferable that the angle θ1 is greater than 0 degrees and less than 90 degrees (0 degrees < θ1 < 90 degrees), and it is preferable that it is greater than 10 degrees and less than 45 degrees (10 degrees < θ1 < 45 degrees).

[0060] Furthermore, the angle θ2 formed by the second inclined portion 142 and the outer circumferential surface of the stationary sealing ring 10 on the upstream side, i.e., the first land 16 side, is approximately 30 degrees. In other words, the second inclined portion 142 is inclined downstream from the inner diameter side to the outer diameter side.

[0061] This makes it easier to guide the fluid to be sealed F from inside the second inclined portion 142 into the outer space S1 when the rotating sealing ring 20 rotates relative to another. From this viewpoint, it is preferable that the angle θ2 is greater than 0 degrees and less than 90 degrees (0 degrees < θ2 < 90 degrees), and it is preferable that it is greater than 10 degrees and less than 45 degrees (10 degrees < θ2 < 45 degrees).

[0062] As described above, the deep groove 14 can return the sealed fluid F that has flowed in from the first land 16, the second land 17, and the third land 18 back to the outside space S1 by the flow generated when the rotating sealing ring 20 rotates relative to it.

[0063] More specifically, of the sealed fluid F supplied from the shallow groove 13 to the first land 16, most flows circumferentially downstream beyond the deep groove 14, and a portion flows into the deep groove 14 and is collected in the outer space S1. A portion of the sealed fluid F that flows beyond the deep groove 14 into the second land 17 flows circumferentially downstream, flows beyond the downstream deep groove 14 and is supplied to the downstream first land 16, while the remainder flows into the downstream deep groove 14. In this way, since the downstream deep groove 14 is located downstream of the second land 17, it is difficult for the sealed fluid F to leak into the inner space S2.

[0064] Furthermore, when the rotating sealing ring 20 is rotating, a small amount of the sealed fluid F flows beyond the third land 18 to the fourth land 19 on the inner diameter side. This sealed fluid F is subjected to shear force from the sliding surfaces 11 and 21 and moves with a large component in the circumferential direction, so most of it flows into the recovery groove 15. As shown by the solid thin arrows in Figure 3, the sealed fluid F in the recovery groove 15 attempts to move in the rotational direction of the rotating sealing ring 20 due to shear with the sliding surface 21.

[0065] More specifically, the sealed fluid F within the inner diameter extension 150 moves to the downstream inclined section 151. The sealed fluid F within the inclined section 151 then moves to the outer diameter extension 152. The sealed fluid F within the outer diameter extension 152 is guided to its tip 152a and flows out from the tip 152a and its vicinity towards the deep groove 14.

[0066] At this time, positive pressure is generated at the tip 152a and its vicinity, but since the sealed fluid F moving within the recovery groove 15 is small, the force acting axially due to this positive pressure is small and has almost no effect on the operation of the shallow groove 13.

[0067] In this way, the recovery groove 15 can return the sealed fluid F that has moved to the fourth land 19, which is located on the inner space S2 side of the third land 18, back to the deep groove 14.

[0068] Furthermore, by changing the depth, width, and length of the recovery groove 15, the amount of sealed fluid F that can be returned to the deep groove 14 side per unit time can be adjusted.

[0069] Furthermore, since the vector of the sealed fluid F flowing out from the tip 152a and its vicinity includes an outer diameter component, the sealed fluid F is more easily and quickly introduced into the deep groove 14.

[0070] As described above, the positive pressure generated at the tip 152a and its vicinity is smaller than the positive pressure generated at the downstream end 13a and its vicinity in the shallow groove 13. This makes it less likely for the sliding surfaces 11 and 21 to separate excessively. Furthermore, because a deep groove 14 is formed between the shallow groove 13 and the recovery groove 15, the positive pressure generated in the recovery groove 15 is less likely to interfere with the positive pressure generation function of the shallow groove 13.

[0071] Furthermore, the points where positive pressure is generated at end 13a and its vicinity, and the points where positive pressure is generated at tip 152a and its vicinity, are spaced apart in the radial direction, making it easier to achieve radial balance.

[0072] Furthermore, the tip 152a of the recovery groove 15 may be formed downstream of the circumferentially extended portion 141. Even with this configuration, the sealed fluid F can be discharged from the tip 152a to the third land 18 and returned to the deep groove 14 side. On the other hand, as the second inclined portion 142 moves further downstream from the tip 152a, it becomes more difficult for the sealed fluid F to be recovered into the deep groove 14.

[0073] From this viewpoint, it is preferable, as in this embodiment, that the tip 152a is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the circumferential extension portion 141, in order to efficiently allow the recovered sealed fluid F to flow into the deep groove 14. More specifically, on the sliding surface 11, due to shear with the sliding surface 21, even if the sealed fluid F that has flowed out from the tip 152a toward the deep groove 14 moves along the rotational direction of the rotating sealing ring 20 on the third land 18, it is easier for it to flow into the circumferential extension portion 141 and the second inclined portion 142 of the deep groove 14 located downstream of the tip 152a.

[0074] As described above, the mechanical seal of this embodiment allows the first land 16 surrounded by the deep groove 14 to slide smoothly with the sealed fluid F supplied from the shallow groove 13, and the sealed fluid F that has moved to the inner space S2 side of the deep groove 14 can be returned to the deep groove 14 by the recovery groove 15. As a result, even in a low-pressure environment, leakage of the sealed fluid F can be suppressed while the stationary sealing ring 10 and the rotating sealing ring 20 can slide smoothly.

[0075] Furthermore, due to its viscosity and surface tension, the sealed fluid F solidifies and adheres to the recovery groove 15, making it less likely to immediately scatter into the internal space S2.

[0076] Furthermore, since the recovery groove 15 is in communication with the inner space S2, if the amount of sealed fluid F that flows in instantaneously increases, the excess sealed fluid F can be discharged into the inner space S2 or adhere to the inner surface of the stationary sealing ring 10. This prevents the generation of unexpected positive pressure from the recovery groove 15. In addition, as time passes, all or part of the sealed fluid F adhering to the inner surface of the stationary sealing ring 10 moves into the recovery groove 15 due to surface tension and viscosity, thus reducing the loss of sealed fluid F.

[0077] For example, as shown in Figure 6(b), in a recovery groove 215 that is not in communication with the internal space S2, an unexpected positive pressure is likely to occur as the amount of sealed fluid F that flows in instantaneously increases. As a result, if the sliding surfaces 11 and 21 are excessively separated, the suction force on the internal space S2 side may exceed the viscous force, surface tension, and shear force acting on the sealed fluid F, and there is a risk that a large amount of sealed fluid F will leak out from between the sliding surfaces 11 and 21.

[0078] In this way, the recovery groove 15 can maintain an appropriate distance between the sliding surfaces 11 and 21, and can maintain a balance between the shear force acting on the sealed fluid F in the recovery groove 15 and the suction force on the inner space S2 side.

[0079] Furthermore, since the recovery groove 15 has an inner diameter extension 150 that extends circumferentially along the edge 11a on the inner space S2 side of the sliding surface 11, the sealed fluid F can be recovered over a wide area in the radial direction.

[0080] For example, as shown in Figure 6(b), in a recovery groove 215 that is not in communication with the internal space S2, the sealed fluid F that has moved to the edge 11a on the internal space S2 side of the sliding surface 11 does not easily flow into the recovery groove 215. Therefore, it is difficult to recover the sealed fluid F that has moved to the edge 11a or the inner circumferential surface of the stationary sealing ring 10.

[0081] Furthermore, the entire recovery groove 15 is positioned on the inner diameter side of the deep groove 14. This makes it more difficult for the sealed fluid F that flows to the second land 17 without being recovered in the deep groove 14 to flow directly into the recovery groove 15, compared to, for example, the case where the recovery groove 315 shown in Figure 6(c) extends to a position upstream and on the outer diameter side of the circumferential extension portion 141 in the deep groove 14. As a result, the sealed fluid F that moves to the inner diameter side of the deep groove 14 and flows into the recovery groove 15 can be smoothly returned to the deep groove 14.

[0082] Furthermore, since the shallow grooves 13, deep grooves 14, and recovery grooves 15 are provided in multiple locations spaced apart in the circumferential direction, the sealed fluid F can be recovered over a wide area in the circumferential direction while the sliding surfaces 11 and 21 slide against each other in a balanced manner. Moreover, the deep grooves 14 are provided in multiple locations spaced apart in the circumferential direction and are not annular grooves. Therefore, when stationary, the sealed fluid F is introduced into the deep grooves 14 at a pressure higher than that of the inner space S2, but since the pressure gradually decreases from the outer diameter side to the inner diameter side, the sealed fluid F is less likely to leak to the inner diameter side.

[0083] Furthermore, since the recovery groove 15 has an inner diameter extension portion 150 and an inclined portion 151 provided on the inner space S2 side downstream from the circumferential center of the second land 17, the sealed fluid F that flows downstream from the second land 17 toward the inner space S2 can be efficiently recovered.

[0084] From this perspective, although not shown directly in the illustration, the recovery groove 15 may, in whole or in part, extend upstream of the circumferential center of the second land 17, for example, by having the entire inclined portion 151 located on the inner diameter side of the first inclined portion 140 in the deep groove 14. With such a configuration, the sealed fluid F can be recovered more efficiently.

[0085] Furthermore, as shown by the dashed line in Figure 3, the inner diameter extension 150' may be provided on the inner diameter side of the entire circumferential position between the communication opening 140a of the first inclined portion 140 in the deep groove 14 and the communication opening 142a of the second inclined portion 142 in the deep groove 14 adjacent to it upstream.

[0086] In other words, the inner diameter extension 150' may extend until its upstream end 150a' reaches the inner diameter side at approximately the same circumferential position as the communication opening 142a of the second inclined portion 142 in the upstream deep groove 14, or it may extend further upstream than the communication opening 142a. Thus, the inner diameter extension is preferable in that the more the area of ​​the inner diameter extension that extends upstream and is located on the inner diameter side of the upstream deep groove 14 increases, the easier it is to improve the recovery efficiency of the sealed fluid F.

[0087] In this embodiment, the dynamic pressure generating groove is described as a shallow groove 13 communicating with the introduction groove 12, but it is not limited to this and may be modified as appropriate.

[0088] For example, as shown in the example shape 1-1 of Figure 4(a), the dynamic pressure generating groove may be a shallow groove 113 extending circumferentially from the radial center of the first inclined portion 140 in the deep groove 14. Even with such a configuration, the shallow groove 113 can function as a Rayleigh step that generates positive pressure at the downstream end 113a and its vicinity.

[0089] Furthermore, the shallow groove 113 is connected to the first inclined section 140 through which the sealed fluid F flows smoothly from the outer space S1. As a result, the shallow groove 113 can generate positive pressure more efficiently than the shallow groove 13.

[0090] Furthermore, the circumferential length from end 113a to the second inclined portion 142 can be made longer than the circumferential length from end 13a to the second inclined portion 142 in the shallow groove 13. As a result, the first land 116 is better able to retain the sealed fluid F for a longer period than the first land 16.

[0091] Although the radial position in which the shallow groove 113 communicates with the first inclined portion 140 may be changed as appropriate, a position closer to the radial center is preferable from the viewpoint of allowing the sealed fluid F to remain in the first land 116 for a longer period of time.

[0092] Here, the circumferential length L11 of the shallow groove 113 is approximately half the circumferential length L12 of the first land 116 (L11 = L12 × 1 / 2). The circumferential length L12 of the first land 116 is the sum of the circumferential length L11 and the circumferential length of the first land 116 downstream of the shallow groove 113 (L12 - L11).

[0093] In other words, the longer the circumferential length (L12-L11) downstream of the shallow groove 113 in the first land 116, the longer the sealed fluid F supplied from the end 113a can be retained in the first land 116, making it easier to slide more stably. From this viewpoint, it is preferable that the circumferential length L11 is approximately half or less of the circumferential length L12 (L11 <L12×1 / 2)。

[0094] Furthermore, the dynamic pressure generating groove may be an inclined groove 213 that communicates with the outer space S1 and extends inclined downstream and toward the inner diameter, as shown in the shape example 1-2 of Figure 4(b). Also, as shown in the shape example 1-3 of Figure 4(c), the dynamic pressure generating groove may be a so-called herringbone groove 313, which is formed in an L-shape when viewed from the axial direction where an outer diameter inclined groove that communicates with the outer space S1 and extends inclined downstream and toward the inner diameter intersects with an inner diameter inclined groove that extends inclined further outward and downstream than the inner diameter. Moreover, multiple dynamic pressure generating grooves, such as the inclined groove 213 and the herringbone groove 313, may be provided.

[0095] On the other hand, shallow grooves 13 and 113 are preferable to inclined grooves 213 and herringbone grooves 313 from the viewpoint of supplying a sufficient amount of the fluid to be sealed F to the land from the dynamic pressure generating groove and making it easier to retain the fluid to be sealed F on the land for a longer period of time.

[0096] Although not shown directly in the illustration, both shallow grooves 113 and inclined grooves 213 may be formed. In this way, multiple dynamic pressure generating grooves of different shapes may be arranged.

[0097] Furthermore, although this embodiment describes a configuration in which the first groove has a first inclined portion 140, a circumferentially extended portion 141, and a second inclined portion 142, it is not limited to this configuration, and any configuration that surrounds the dynamic pressure generating groove and communicates with the sealed fluid space side may be appropriately modified.

[0098] For example, as shown in the shape example 1-4 of Figure 5(a), the first groove may be a deep groove 114 having a first radially extended portion 240 extending radially toward the outer diameter from both ends in the circumferential direction of the circumferentially extended portion 241, and a second radially extended portion 242.

[0099] Even with this configuration, the fluid to be sealed F can flow in the order of the first radially extended portion 240, the circumferentially extended portion 141, and the first radially extended portion 240 in accordance with the rotation of the rotating sealing ring 20. On the other hand, as mentioned above, from the viewpoint of easily generating the flow of the fluid to be sealed F, a deep groove 14 having a first inclined portion 140 and a second inclined portion 142 is preferable.

[0100] Furthermore, as shown in the shape examples 1-5 of Figure 5(b), the first groove may be a deep groove 214 in which the inner diameter ends of the first inclined portion 340 and the second inclined portion 342 are in direct communication.

[0101] Even with this configuration, the sealed fluid F can flow smoothly through the first inclined section 340 and the second inclined section 342 in that order. On the other hand, from the viewpoint of easily securing a wide land surrounded by the deep groove, a deep groove 14 having a circumferentially extended section 141 is preferable.

[0102] Furthermore, although the recovery groove 15 was described as a Z-shaped groove in this embodiment, it is not limited to this and may be modified as appropriate as long as it can guide the sealed fluid F to the outer space S1.

[0103] For example, as shown in the shape example 1-6 of Figure 6(a), the second groove may be an inclined groove 115 that extends inclined from the inner diameter side towards the outer diameter side and downstream side.

[0104] Even with this configuration, the sealed fluid F in the inclined groove 115 can be guided to the tip 115a by shearing with the sliding surface 21 and returned to the deep groove 14 side. On the other hand, a recovery groove 15 having an inner diameter extension 150 is preferable from the viewpoint of easily recovering the sealed fluid F that has moved to the inner space S2 side at a wide radial position.

[0105] Furthermore, as shown in the shape examples 1-7 of Figure 6(b), the second groove may be a recovery groove 215 that does not communicate with the inner space S2. With such a configuration, when the rotating sealing ring 20 is not rotating, the sealed fluid F in the recovery groove 215 is less likely to leak into the inner space S2. On the other hand, as mentioned above, a recovery groove 15 that communicates with the inner space S2 is preferable from the viewpoint of easily reducing the amount of sealed fluid F that flows into the inner space S2 when an excessive amount flows between the sliding surfaces.

[0106] Furthermore, as shown in the shape example 1-8 of Figure 6(c), the second groove may be a recovery groove 315 that extends to the second land 317.

[0107] Even with this configuration, the sealed fluid F supplied from the recovery groove 315 to the land can be efficiently flowed into the deep groove 14. On the other hand, as described above, there is a risk that the sealed fluid F will flow directly from the second land 317 to the recovery groove 315, and the recovery efficiency of the sealed fluid F that has moved to the inner diameter side of the deep groove 14 will be reduced. From this viewpoint, it is preferable that the second groove be formed on the inner diameter side of the deep groove 14, like the recovery groove 15.

[0108] Furthermore, scratches caused by contaminants or other particles getting caught between the sliding surfaces tend to extend circumferentially along the direction of rotation. When these scratches cause the deep groove 14 and the recovery groove 315 to communicate, the sealed fluid F in the deep groove 14 communicates with the internal space S2 through the recovery groove 315. From this viewpoint as well, it is preferable that the second groove, like the recovery groove 15, is formed on the lower-pressure side of the deep groove 14. [Examples]

[0109] Next, the sliding parts according to Embodiment 2 will be described with reference to Figures 7 and 8. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0110] As shown in Figure 7, the stationary sealing ring 410 of Embodiment 2 is designed for both counterclockwise and clockwise rotation of the rotating sealing ring 20, as indicated by the solid arrows.

[0111] In this embodiment, forward rotation means that the rotating sealing ring 20 is rotating counterclockwise, and reverse rotation means that the rotating sealing ring 20 is rotating counterclockwise. Unless otherwise specified, the description will assume that the rotating sealing ring 20 rotates counterclockwise, as in Embodiment 1.

[0112] The sliding surface 411 is provided with eight shallow grooves 113, eight reverse shallow grooves 413, eight deep grooves 14, and eight recovery grooves 415.

[0113] The inverted shallow groove 413 extends circumferentially from the radial center of the second inclined portion 142 in the deep groove 14 toward the upstream side.

[0114] The recovery groove 415 is symmetrical with respect to a radially extending line passing through its circumferential center. The recovery groove 415 has an inner diameter extension 550 extending in the circumferential direction, an inclined section 151, an outer diameter extension 152, a reverse inclined section 551 extending from the upstream end of the inner diameter extension 150 toward the outer diameter and upstream, and a reverse outer diameter extension 552 extending circumferentially toward the upstream from the outer diameter end of the reverse inclined section 551.

[0115] The inner diameter extension 550 has a circumferential length that is approximately twice the circumferential length of the inner diameter extension 150.

[0116] The inner diameter extension 550 and the reverse inclined portion 551 are located on the inner diameter side of the second land 17. The circumferential center of the inner diameter extension 550 is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the second land 17.

[0117] The reverse outer diameter extension portion 552 extends substantially parallel to the circumferential extension portion 141 in the deep groove 14.

[0118] Furthermore, the inverse outer diameter extension 552 has an acute angle shape at its tip 552a, which tapers toward the upstream side. The tip 552a is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the circumferential extension 141.

[0119] The tip 152a of the outer diameter extension 152 and the tip 552a of the reverse outer diameter extension 552 are formed at approximately the same radial position and are spaced apart in the circumferential direction.

[0120] Next, we will explain the sealing between the outer space S1 and the inner space S2 by the stationary sealing ring 410 and the rotating sealing ring 20.

[0121] First, we will explain the case where the rotating sealing ring 20 slides counterclockwise relative to the stationary sealing ring 410, as shown by the solid arrow in Figure 8.

[0122] The sealed fluid F in the inverted shallow groove 413 attempts to move in the rotational direction of the rotating sealing ring 20 due to shear with the sliding surface 21. The sealed fluid F is guided downstream along the inverted shallow groove 413 and flows into the second inclined portion 142 in the deep groove 14.

[0123] Furthermore, a relative negative pressure is generated on the upstream side of the inverted shallow groove 413. This negative pressure increases as you approach the upstream end 413a of the inverted shallow groove 413. This negative pressure allows the inverted shallow groove 413 to recover the sealed fluid F from the first land 416 while preventing the rotating sealing ring 20 from moving excessively axially away from the stationary sealing ring 410. In other words, the inverted shallow groove 413 functions as an inverted Rayleigh step.

[0124] Referring to Figure 7, the circumferential length L21 of the shallow groove 113 and the circumferential length L21 of the inverted shallow groove 413 are approximately the same. The sum of these circumferential lengths L21 (L21 × 2) is approximately one-third of the circumferential length L22 of the first land 416 (L21 × 2 = L22 × 1 / 3). In other words, the circumferential length L21 is approximately one-sixth of the circumferential length L22 (L21 = L22 × 1 / 6). The circumferential length L22 of the first land 416 is the sum of the circumferential lengths L21 of the shallow groove 113 and the inverted shallow groove 413 (L21 × 2) and the circumferential length of the first land 416 from downstream of the shallow groove 113 to upstream of the inverted shallow groove 413 (L22 - L21 × 2).

[0125] In other words, the longer the circumferential length (L22 - L21 × 2) of the first land 416 from downstream of the shallow groove 113 to upstream of the reverse shallow groove 413, the longer the sealed fluid F supplied from the end 113a to the first land 416 can remain in the first land 416, making it easier to slide more stably. From this viewpoint, it is preferable that the sum of the circumferential length L21 of the shallow groove 113 and the circumferential length 21 of the reverse shallow groove 413 (L21 × 2) is approximately half or less of the circumferential length L22 (L21 × 2 <L22×1 / 2)。

[0126] As shown by the solid thin arrows in Figure 8, the sealed fluid F in the reverse outer diameter extension 552 of the recovery groove 415 flows into the reverse inclined section 551. The sealed fluid F in the reverse inclined section 551 flows into the inner diameter extension 550. The sealed fluid F in the inner diameter extension 550 flows into the inclined section 151. Also, similar to Embodiment 1, the sealed fluid F in the recovery groove 415 flows out from the tip 152a and its vicinity towards the deep groove 14.

[0127] In the recovery groove 415, the reverse-sloping portion 551 and the reverse-outer-diameter extension portion 552 are positioned closer in the circumferential direction to the downstream tip 152a of the upstream recovery groove 415, which is adjacent in the circumferential direction to the upstream end 150a of the recovery groove 15 in the embodiment 1.

[0128] As a result, the recovery groove 415 facilitates the rapid recovery of the sealed fluid F that flows out from the downstream tip 152a of the upstream recovery groove 415, even if it moves inward beyond the third land 18.

[0129] Next, we will describe the case where the rotating sealing ring 20 slides clockwise relative to the stationary sealing ring 410, as shown by the dashed arrow in Figure 8. Note that the explanation similar to that for the case where the rotating sealing ring 20 slides counterclockwise relative to the stationary sealing ring 410 will be omitted or simplified.

[0130] The sealed fluid F flows from the outer space S1 into the second inclined section 142 in the deep groove 14, passes through the circumferentially extended section 141, and flows out into the outer space S1 from the first inclined section 140.

[0131] The sealed fluid F in the shallow groove 113 is guided downstream in the reverse rotation direction and flows into the first inclined section 140. Furthermore, a relative negative pressure is generated upstream of the shallow groove 113. In other words, the shallow groove 113 functions as a reverse Rayleigh step.

[0132] The sealed fluid F within the reverse shallow groove 413 is guided downstream in the reverse rotation direction and supplied to the first land 416 from the downstream end 413a and its vicinity in the reverse rotation direction. Positive pressure is also generated at the downstream end 413a and its vicinity in the reverse rotation direction. In other words, the reverse shallow groove 413 functions as a Rayleigh step.

[0133] The sealed fluid F in the outer diameter extension 152 of the recovery groove 415 flows into the inclined section 151. The sealed fluid F in the inclined section 151 flows into the inner diameter extension 550. The sealed fluid F in the inner diameter extension 550 flows into the reverse inclined section 551. The sealed fluid F in the reverse inclined section 551 flows into the reverse outer diameter extension 552. The sealed fluid F in the reverse outer diameter extension 552 is guided to its tip 552a and flows out to the third land 18 from the tip 552a and its vicinity.

[0134] Furthermore, since the tip 552a is located on the inner diameter side at approximately the same circumferential position as the circumferential center of the circumferential extension portion 141, it facilitates flow into the circumferential extension portion 141 and the first inclined portion 140 located downstream in the reverse rotation direction from the tip 552a.

[0135] As described above, in this embodiment, since the mechanical seal is provided with a shallow groove 113 and a reverse shallow groove 413 in a single deep groove 14, it is possible to keep the sealed fluid F on the first land 416 for a longer period of time, whether rotating in the forward or reverse direction, while preventing an excess of the sealed fluid F on the first land 416.

[0136] Furthermore, the sliding surface 411 is provided with a shallow groove 113 that functions as a dynamic pressure generating groove for forward rotation, a reverse shallow groove 413 that functions as a dynamic pressure generating groove for reverse rotation, and a recovery groove 415 that functions as both a recovery groove for forward rotation and a recovery groove for reverse rotation. As a result, lubrication can be performed while suppressing leakage of the sealed fluid F, regardless of the direction of rotation, even in a low-pressure environment.

[0137] Furthermore, since the recovery groove 415 is symmetrical with respect to a radially extending line passing through its circumferential center, it can generate similar levels of positive pressure and flow of the sealed fluid F when the rotational speed is the same during forward and reverse rotation.

[0138] Furthermore, the second groove may be asymmetrical, with different volumes for the portion that functions as a recovery groove during forward rotation and the portion that functions as a recovery groove during reverse rotation. With such a configuration, appropriate positive pressure and flow of the sealed fluid F can be generated even when the expected rotational speeds differ between forward and reverse rotation. [Examples]

[0139] Next, the sliding parts according to Embodiment 3 will be described with reference to Figure 9. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0140] As shown in Figure 9, the stationary sealing ring 610 of Embodiment 3 is designed for both rotation and rotation. Unless otherwise specified, the description will assume that the rotating sealing ring 20 rotates counterclockwise, as in Embodiment 1.

[0141] The sliding surface 611 is provided with one deep groove 614, one shallow groove 113, one reverse shallow groove 413, three recovery grooves 15, and three reverse recovery grooves 615.

[0142] The three recovery grooves 15 are located upstream of the circumferential center of the circumferentially extending portion 741 in the deep groove 614.

[0143] The reverse recovery groove 615 has a shape that is symmetrical to the recovery groove 15 with respect to a radially extending line, and has an inner diameter extension portion 750, a reverse inclined portion 551, and a reverse outer diameter extension portion 552.

[0144] The three reverse recovery grooves 615 are located downstream of the circumferential center of the circumferential extension portion 741 in the deep groove 614.

[0145] Next, we will explain the sealing between the outer space S1 and the inner space S2 by the stationary sealing ring 610 and the rotating sealing ring 20.

[0146] First, we will explain the case where the rotating sealing ring 20 slides counterclockwise relative to the stationary sealing ring 410, as shown by the solid arrow in Figure 9.

[0147] As shown by the solid thin arrows in Figure 9, the sealed fluid F in each recovery groove 15 is guided to the tip 152a of the recovery groove 15 and flows out toward the deep groove 614.

[0148] Furthermore, among the adjacent recovery grooves 15 in the circumferential direction, the inner diameter extension 150 of the downstream recovery groove 15 is positioned on the inner diameter side of the upstream recovery groove 15 than the outer diameter extension 152 of the upstream recovery groove 15.

[0149] As a result, even if the sealed fluid F that flows out from the tip 152a of the upstream recovery groove 15 moves to the inner diameter side of the third land 18, it can be quickly recovered by the downstream recovery groove 15. In addition, the sealed fluid F that passes through the upstream recovery groove 15 in the circumferential direction can be quickly recovered by the downstream recovery groove 15.

[0150] As shown by the solid thin arrows in Figure 9, the sealed fluid F in each reverse recovery groove 615 is guided to the downstream end 750a of the inner diameter extension 750 and flows out into the land.

[0151] Furthermore, the sealed fluid F that flows out from the downstream end 750a of the reverse recovery groove 615 flows into the adjacent downstream reverse recovery groove 615 or recovery groove 15. In other words, the sealed fluid F that has moved downstream beyond the three recovery grooves 15 is transferred from the reverse recovery groove 615 to the downstream reverse recovery groove 615 as it moves downstream, and is easily recovered by one of the recovery grooves 15 located downstream. This makes it even less likely for the sealed fluid F to leak into the internal space S2.

[0152] Furthermore, among the circumferentially adjacent reverse recovery grooves 615, the reverse outer diameter extension 552 of the downstream reverse recovery groove 615 is positioned on the outer diameter side of the upstream reverse recovery groove 615 than the inner diameter extension 750 of the upstream reverse recovery groove 615.

[0153] This allows the sealed fluid F that has flowed out from end 750a of the upstream reverse recovery channel 615 to flow quickly into the downstream reverse recovery channel 615.

[0154] Next, we will describe the case where the rotating sealing ring 20 slides clockwise relative to the stationary sealing ring 410, as shown by the dashed arrow in Figure 9. Note that the explanations similar to those for the case where the rotating sealing ring 20 slides counterclockwise relative to the stationary sealing ring 410 will be omitted or simplified.

[0155] The sealed fluid F in each reverse recovery groove 615 is guided to the tip 552a of the reverse outer diameter extension 552 and flows out toward the deep groove 614.

[0156] Furthermore, the sealed fluid F in each recovery groove 15 flows out to the land from the downstream end 150a in the reverse rotation direction of the inner diameter extension portion 150, and flows into the recovery groove 15 or reverse recovery groove 615 on the downstream side in the reverse rotation direction. This further reduces the likelihood of the sealed fluid F leaking into the internal space S2.

[0157] As described above, the mechanical seal of this embodiment can cause the sealed fluid F to flow out from the three recovery grooves 15 toward the deep groove 614 during forward rotation, and can cause the sealed fluid F to flow out from the three reverse recovery grooves 615 toward the deep groove 614 during reverse rotation.

[0158] In this embodiment, a configuration is provided in which a plurality of recovery grooves 15 and a plurality of reverse recovery grooves 615, which are not in communication with each other, are provided in a single deep groove 614, as an example of a configuration that allows the sealed fluid F to flow out from a plurality of second grooves toward a single first groove. However, this configuration may be modified as appropriate.

[0159] For example, as shown in the shape example 3-1 of Figure 10, the recovery groove 815 may have three inclined sections 151, three outer diameter extensions 152, three reverse inclined sections 551, and three reverse outer diameter extensions 552 that communicate with one inner diameter extension 950.

[0160] Even with this configuration, the sealed fluid F can be discharged from the three outer diameter extensions 152 toward the deep groove 614 during forward rotation, and from the three reverse outer diameter extensions 552 toward the deep groove 614 during reverse rotation.

[0161] Furthermore, during forward rotation, the sealed fluid F that flows into either the reverse inclined portion 551 or the reverse outer diameter extension portion 552 in one of the recovery grooves 815 can be guided through the inner diameter extension portion 950 to the outer diameter extension portion 152 located downstream. Similarly, during reverse rotation, the sealed fluid F that flows into the inclined portion 151 or the outer diameter extension portion 152 can be guided through the inner diameter extension portion 950 to the reverse outer diameter extension portion 552 located downstream in the reverse rotation direction.

[0162] Although not shown directly, the second groove located on the inner diameter side of the second land 17 may be designated as the recovery groove 415 in the above embodiment 2, with at least one reverse recovery groove 615 positioned upstream of the recovery groove 415 and at least one recovery groove 15 positioned downstream. In this way, multiple second grooves of different shapes may be arranged.

[0163] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0164] For example, in the above embodiments 1 to 3, the sliding component was exemplified as a mechanical seal, but it is not limited to this and may be a bearing, or may be changed as appropriate.

[0165] Furthermore, although the sliding component was described as an inside-type mechanical seal in Examples 1 to 3 above, it is not limited to this and may be an outside-type mechanical seal. In other words, the space on the inner diameter side of the sliding component may be the space to be sealed fluid, the space on the outer diameter side may be the low-pressure space, and the dynamic pressure generating groove and deep groove may be arranged on the inner diameter side, while the recovery groove may be arranged on the outer diameter side.

[0166] Furthermore, while embodiments 1 to 3 described a configuration in which a dynamic pressure generating groove, a first groove, and a second groove are formed in a stationary sealing ring, the invention is not limited to this configuration. These grooves may also be provided in a rotating sealing ring, or in both the stationary and rotating sealing rings.

[0167] Furthermore, although the first groove was described as a deep groove in Examples 1 to 3 above, it is not limited to this, and may be approximately the same depth as the dynamic pressure generating groove, or may be changed as appropriate.

[0168] Furthermore, the sealed fluid used as a lubricating medium may be a liquid or a gas, or a mist-like mixture of liquid and gas, but it is preferable that it be a liquid due to its high viscosity and surface tension. [Explanation of Symbols]

[0169] 10 Stationary sealing ring 11 Sliding surface 11a Edge (edge ​​on the low-pressure space side) 13. Shallow groove (dynamic pressure generating groove) 14 Deep groove (first groove) 15. Recovery groove (2nd groove) 16. Land 1 (Land surrounded by deep trenches) 17. Second land (land between adjacent deep trenches in the circumferential direction) 18. Third Round 20 Rotating Sealing Rings 21 Sliding surface 113 Shallow groove (dynamic pressure generating groove) 114 Deep groove (first groove) 115 Slanted groove (2nd groove) 116. Land 1 (Land surrounded by deep trenches) 140 1st slope section (upstream extension section) 141 Circumferential extension part 142 Second slope section (downstream extension section) 213 Inclined groove (dynamic pressure generating groove) 214 Deep groove (1st groove) 215 Recovery groove (2nd groove) 240 First radial extension part (upstream extension part) 241 Circumferential extension part 242 Second radial extension part (downstream extension part) 313 Herringbone groove (dynamic pressure generating groove) 315 Recovery groove (2nd groove) 317 Second land (land between adjacent deep trenches in the circumferential direction) 340 1st slope section (upstream extension section) 342 2nd slope section (downstream extension section) 410 Stationary sealing ring 411 Sliding surface 413 Reverse shallow groove (dynamic pressure generating groove) 415 Recovery groove (2nd groove) 416 Land 1 (Land surrounded by deep trenches) 610 Stationary sealing ring 611 Sliding surface 614 Deep groove (1st groove) 615 Reverse recovery groove (2nd groove) 815 Recovery groove (2nd groove) F Sealed fluid S1 Outside space (sealed fluid space) S2 Internal space (low-pressure space) V vacuum

Claims

1. A sliding component comprising a pair of sliding members arranged at a location where they rotate relative to each other, wherein the sliding surfaces of each sliding member slide relative to each other, thereby dividing a sealed fluid space from a low-pressure space at a lower pressure than the sealed fluid space, A sliding component having at least one of the sliding surfaces, which includes a first groove communicating with the sealed fluid space, a dynamic pressure generating groove located between the sealed fluid space and the first groove, and a second groove extending from the low-pressure space side toward the first groove side.

2. The sliding component according to claim 1, wherein the second groove communicates with the low-pressure space.

3. The sliding component according to claim 2, wherein the second groove has a low-pressure space side extension that extends circumferentially along the edge of the sliding surface on the low-pressure space side.

4. The sliding component according to claim 1, wherein the tip of the second groove on the first groove side is provided upstream of the downstream extension that extends radially downstream in the relative rotation direction of the first groove.

5. The sliding component according to claim 1, wherein the second groove is entirely located on the low-pressure space side of the first groove.

6. The dynamic pressure generating groove is a Rayleigh step connected to the first groove, The sliding component according to claim 1, wherein the circumferential length of the Rayleigh step is less than or equal to half the circumferential length of the land surrounded by the first groove.

7. The sliding component according to any one of claims 1 to 6, wherein the dynamic pressure generating groove, the first groove, and the second groove are provided in a plurality at intervals in the circumferential direction.

8. The sliding component according to claim 7, wherein at least a portion of the second groove is located on the low-pressure space side of the land between adjacent first grooves in the circumferential direction.

9. The dynamic pressure generating groove is provided with a groove extending at least upstream in the relative rotation direction from the sealed fluid space side or the first groove side, and a groove extending at least downstream in the relative rotation direction from the sealed fluid space side or the first groove side. The sliding component according to claim 1, wherein the second groove is provided with a groove extending from the low-pressure space side at least toward the first groove side and upstream in the relative rotation direction, and a groove extending from the low-pressure space side at least toward the first groove side and downstream in the relative rotation direction.

10. The dynamic pressure generating groove is a Rayleigh step connected to the first groove, The first groove is connected to an inverted Rayleigh step that extends toward the Rayleigh step, The sliding component according to claim 9, wherein the sum of the circumferential length of the Rayleigh step and the circumferential length of the inverse Rayleigh step is less than or equal to half the circumferential length of the land enclosed by the first groove.

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