Sliding component

Abstract

The present invention provides a sliding component capable of reducing leakage during reverse rotation.　Provided is a sliding component which partitions a leakage space S1 from a sealed fluid space S2 and in which a pair of sliding surfaces 11, 21 are disposed at locations where the sliding surfaces rotate relative to each other, wherein: one sliding surface 11 is provided with a dynamic pressure generating groove 12 which is disposed on the leakage space S1 side and which extends toward the forward rotation side in the direction of relative rotation, a forward rotation groove 13 which is disposed on the sealed fluid space S2 side and which extends toward the forward rotation side in the direction of relative rotation, and a reverse rotation groove 14 which is disposed on the sealed fluid space S2 side and which extends toward the reverse rotation side in the direction of relative rotation; a closed end 19b of the reverse rotation groove 14 is provided closer to the sealed fluid space S2 side in comparison to the forward rotation groove 13, which is disposed adjacent thereto on the reverse rotation side in the direction of relative rotation; and a communication groove 15 communicating with the sealed fluid space S2 is provided between the reverse rotation groove 14 and the forward rotation groove 13.

Description

Sliding component

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

[0002] As a sliding component for preventing leakage of the fluid to be sealed around the 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. In such a mechanical seal, in recent years, reduction of energy lost due to sliding has been desired for environmental protection measures, and there are some in which dynamic pressure grooves are provided on the sliding surfaces of the sliding rings.

[0003] For example, on the sliding surface of the stationary sealing ring of the mechanical seal shown in Patent Document 1, there are provided a plurality of dynamic pressure generating grooves communicating with the outer space where gas exists, a plurality of release steps communicating with the inner space where the fluid to be sealed exists, and a plurality of reverse release steps communicating with the inner space where the fluid to be sealed exists.

[0004] The plurality of dynamic pressure generating grooves extend obliquely from the outer space side toward the forward rotation side and the inner diameter side. The release step has a liquid guiding groove portion extending in the radial direction and a forward direction groove portion extending along the circumferential direction toward the forward rotation side from the outer diameter end of the liquid guiding groove portion. The reverse release step has a liquid guiding groove portion common to any one of the release steps and a reverse direction groove portion extending along the circumferential direction toward the reverse rotation side from the outer diameter end of the liquid guiding groove portion.

[0005] During the forward rotation of the rotating sealing ring, in the release step, the inflowing fluid to be sealed is guided toward the closed end on the forward rotation side in the forward direction groove portion, and a positive pressure is generated at this closed end and its vicinity. Also, in the dynamic pressure generating groove, the inflowing air is guided toward the closed end on the inner diameter side, and a positive pressure is generated at this closed end and its vicinity. Thus, during forward rotation, due to the positive pressure generated in the release step and the dynamic pressure generating groove, the sliding surfaces are slightly separated from each other, so that the frictional force can be reduced.

[0006] During reverse rotation of the rotating sealing ring, the reverse Rayleigh step guides the incoming sealed fluid toward the closed end on the reverse rotation side of the reverse groove, generating positive pressure at and near this closed end. Thus, during reverse rotation, the positive pressure generated in the reverse Rayleigh step causes the sliding surfaces to separate slightly, thereby reducing frictional force.

[0007] International Publication No. 2023 / 223914 (pp. 8-10, Figure 3)

[0008] In mechanical seals like the one described in Patent Document 1, when rotating in the forward direction, the fluid to be sealed that flows between the sliding surfaces is pushed back towards the inner space by the positive pressure generated by the dynamic pressure generating groove, making leakage less likely. On the other hand, when rotating in the reverse direction, the air flowing into the dynamic pressure generating groove is guided towards the outer space, and a larger negative pressure is likely to be generated as it approaches the closed end. This negative pressure could guide the fluid to be sealed between the sliding surfaces towards the dynamic pressure generating groove, potentially causing leakage.

[0009] This invention was made in view of these problems, and aims to provide a sliding part that can reduce leakage during reverse rotation.

[0010] To solve the aforementioned problems, the present invention provides a sliding component which is arranged at a location where a pair of sliding surfaces rotate relative to each other and separates a leak space from a sealed fluid space, wherein one of the sliding surfaces comprises a dynamic pressure generating groove arranged on the leak space side and extending in the forward rotation direction of the relative rotation, a forward rotation groove arranged on the sealed fluid space side and extending in the forward rotation direction of the relative rotation, and a reverse rotation groove arranged on the sealed fluid space side and extending in the reverse rotation direction of the relative rotation, wherein the closed end of the reverse rotation groove is provided on the sealed fluid space side than the forward rotation groove, and a communication groove is provided between the reverse rotation groove and the forward rotation groove that communicates with the sealed fluid space. With this, when rotating in reverse, the communication groove located on the leak side of the closed end of the reverse rotation groove and the forward rotation groove on the reverse rotation side of the relative rotation can hinder the movement of the sealed fluid supplied from the reverse rotation groove to the sliding surface side towards the leak space, thereby reducing leakage.

[0011] The reverse rotation groove and the forward rotation groove may overlap radially. This allows for efficient inhibition of the movement of the sealed fluid supplied from the reverse rotation groove to the leakage space side during reverse rotation.

[0012] The forward rotation groove has a shallow groove for forward rotation extending toward the forward rotation side in the relative rotation direction, and the reverse rotation groove has a shallow groove for reverse rotation extending toward the reverse rotation side in the relative rotation direction, and the entire reverse rotation shallow groove may radially overlap the forward rotation shallow groove. This makes it possible to more efficiently inhibit the movement of the sealed fluid supplied from the reverse rotation groove to the leakage space side when it rotates in the reverse direction.

[0013] The forward rotation groove has a shallow forward rotation groove extending toward the forward rotation side in the relative rotation direction and a forward rotation outlet / inlet groove communicating with the sealed fluid space, and the reverse rotation groove has a shallow reverse rotation groove extending toward the reverse rotation side in the relative rotation direction and a reverse rotation outlet / inlet groove communicating with the sealed fluid space, and the forward rotation outlet / inlet groove and the reverse rotation outlet / inlet groove may be independent of each other. This makes it possible to prevent the dynamic pressure generated in the reverse rotation groove and the dynamic pressure generated in the forward rotation groove from interfering with each other.

[0014] The forward rotation groove has a shallow groove for forward rotation extending toward the forward rotation side in the relative rotation direction, and the reverse rotation groove has a shallow groove for reverse rotation extending toward the reverse rotation side in the relative rotation direction. The forward rotation groove and the reverse rotation groove share an outlet / inlet groove that communicates with the sealed fluid space, and the forward rotation shallow groove and the reverse rotation shallow groove may communicate with the outlet / inlet groove. With this configuration, the sealed fluid recovered in the reverse rotation groove during forward rotation can be supplied to the forward rotation groove through the outlet / inlet groove, and the sealed fluid recovered in the forward rotation groove can be supplied to the reverse rotation groove during reverse rotation, thereby increasing the dynamic pressure generation efficiency.

[0015] The dynamic pressure generating groove may be a plurality of spiral grooves communicating with the leakage space. This reduces leakage of the sealed fluid during forward rotation.

[0016] The spiral grooves that do not overlap radially with the forward rotation grooves may be shorter than the other spiral grooves. This allows for a further reduction in leakage of the sealed fluid during reverse rotation.

[0017] This is a longitudinal cross-sectional view showing an example of a mechanical seal in Embodiment 1 of the present invention. This is a view of the sliding surface of the stationary sealing ring as seen from the axial direction. This is an enlarged view of the main part of Figure 2 during forward rotation. This is an enlarged view of the main part of Figure 2 during reverse rotation. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Embodiment 2 of the present invention. This is an enlarged view of the main part of the sliding surface of the stationary sealing ring in Modification 2-1 of Embodiment 2. 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. This is a view of the stationary sealing ring in Embodiment 4 of the present invention as seen from the axial direction. This is a view of the stationary sealing ring in Modification 4-1 of Embodiment 4 as seen from the axial direction. This is a view of the stationary sealing ring in Embodiment 5 of the present invention as seen from the axial direction.

[0018] Embodiments for implementing the sliding component according to the present invention will be described below based on examples.

[0019] The sliding component according to Example 1 will be described with reference to Figures 1 to 4. In this example, a mechanical seal will be used as an example of a sliding component. Also, for the sake of clarity, dots may be added to grooves and other features formed on the sliding surface in the drawings.

[0020] The mechanical seal shown in Figure 1 separates an inner space S1, which is a leakage space, from an outer space S2, which is the space for the fluid to be sealed. The inner space S1 contains air as gas A. The outer space S2 contains liquid F, which is the fluid to be sealed, such as oil. The outer space S2 is under higher pressure than the inner space S1. In other words, the mechanical seal is an inside type that seals the liquid F that would otherwise leak from the outer space S2 towards the inner space S1. In this embodiment, a configuration in which gas A is under lower pressure than liquid F is illustrated. The types of gas A and liquid F may be changed as appropriate.

[0021] The mechanical seal comprises a stationary sealing ring 10 and a rotating sealing ring 20. The stationary sealing ring 10 is provided on a seal cover 5 fixed to the housing 4 of the equipment to be mounted, in a non-rotatable and axially movable state. The rotating sealing ring 20 is attached to a sleeve 2 fixed to a rotating shaft 1 and is rotatable together with the rotating shaft 1.

[0022] The stationary sealing ring 10 is biased axially by the elastic member 7. The sliding surface 11 of the stationary sealing ring 10, which serves as one sliding surface, and the sliding surface 21 of the rotating sealing ring 20, which serves as the other sliding surface, are in close contact with each other. The sliding surface 21 of the rotating sealing ring 20 is a flat surface and 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, or carbon 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, or SiC-TiN. 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 is slidable relative to the stationary sealing ring 10 in a counterclockwise direction as indicated by the solid arrow, and also slidable relative to the stationary sealing ring 10 in a clockwise direction as indicated by the dashed arrow.

[0025] In this embodiment, the relative sliding of the rotating sealing ring 20 counterclockwise is defined as forward rotation, and the relative sliding of it clockwise is defined as reverse rotation. Furthermore, in this embodiment, unless otherwise specified, the explanation will be based on the assumption of forward rotation. In forward rotation, the side clockwise from the position of the object will be described as the upstream side in the forward rotation direction, and the side counterclockwise from the position of the object will be described as the downstream side in the forward rotation direction. In reverse rotation, the side clockwise from the position of the object will be described as the downstream side in the reverse rotation direction, and the side counterclockwise from the position of the object will be described as the upstream side in the reverse rotation direction.

[0026] The sliding surface 11 of the stationary sealing ring 10 is provided with 24 spiral grooves 12 as dynamic pressure generating grooves, 3 sets of Rayleigh steps 13 as forward rotation grooves, 3 sets of reverse Rayleigh steps 14 as reverse rotation grooves, and 3 circulation grooves 15. On the sliding surface 11, the parts other than the spiral grooves 12, Rayleigh steps 13, reverse Rayleigh steps 14, and circulation grooves 15 form flat lands 11a.

[0027] Although the 24 spiral grooves 12 are equally spaced, their number and arrangement may be changed as appropriate. The same applies to the three sets of Rayleigh steps 13, the three sets of reverse Rayleigh steps 14, and the three circulating grooves 15.

[0028] Referring to Figure 3, the spiral groove 12 has an open end 12a on the inner diameter side that communicates with the inner space S1, and extends in an arc shape from the open end 12a toward the outer diameter side and toward the downstream side in the forward rotation direction, while inclined. The spiral groove 12 has an arc shape that protrudes toward the outer diameter side and toward the upstream side in the forward rotation direction. The outer diameter side end of the spiral groove 12 is a closed end 12b that is closed so as not to communicate with the outer space S2.

[0029] In the following explanation, the upstream side in the forward rotation direction may simply be referred to as the "upstream side," and the downstream side in the forward rotation direction may simply be referred to as the "downstream side." Similarly, the upstream side in the reverse rotation direction may simply be referred to as the "reverse upstream side," and the downstream side in the reverse rotation direction may simply be referred to as the "reverse downstream side."

[0030] The spiral groove 12 has a substantially constant depth, i.e., axial length, from the open end 12a to the closed end 12b.

[0031] The depth of the spiral groove 12 may change, for example, becoming shallower from the open end 12a to the closed end 12b. The cross-sectional shape of the spiral groove 12 is rectangular, but it may also be U-shaped, semicircular, or triangular, and may be changed as appropriate. The same applies to the Rayleigh step 13, the inverted Rayleigh step 14, and the circulation groove 15.

[0032] The Rayleigh step 13 is formed in an L-shape, inverted left and right when viewed from the axial direction, and has a first deep groove 16 as an inlet / outlet groove for forward rotation and a first shallow groove 17 as a shallow groove for forward rotation. The shallow groove for forward rotation in this invention may be any shallow groove having a closed end that contributes to the generation of positive pressure during forward rotation.

[0033] The first deep groove 16 is a groove of constant depth that extends radially, with its outer diameter end 16a communicating with the outer space S2. The inner diameter end 16b of the first deep groove 16 is closed. The first deep groove 16 is deeper than the spiral groove 12.

[0034] The first shallow groove 17 is a groove of constant depth that extends along the circumferential direction. The upstream end of the first shallow groove 17 is an open end 17a that communicates with the downstream side of the inner diameter end 16b of the first deep groove 16. The downstream end of the first shallow groove 17 is a closed end 17b. The first shallow groove 17 is slightly shallower than the spiral groove 12 and shallower than the first deep groove 16.

[0035] In addition, while the example given for the inlet / outlet groove is a first deep groove 16 that is deeper than the first shallow groove 17, it is not limited to this, and may be a groove of the same depth as the first shallow groove 17, or a groove shallower than the first shallow groove 17, or a groove of the same depth as the spiral groove 12, or a groove shallower than the spiral groove 12, and may be changed as appropriate. On the other hand, a deeper inlet / outlet groove is preferable from the viewpoint of being able to store liquid F and prevent poor lubrication. Similarly, the depth of the dynamic pressure generating groove, the shallow groove for forward rotation, and the shallow groove for reverse rotation may also be changed as appropriate.

[0036] In other words, the depths of the dynamic pressure generating groove, the forward rotation side groove, and the reverse rotation side groove may be set individually. Furthermore, if it is composed of multiple parts, as in the Rayleigh step 13 of this embodiment, the depth of each part may be set individually.

[0037] The reverse Rayleigh step 14 is located downstream of the adjacent upstream Rayleigh step 13 in the circumferential direction and is formed in an L-shape when viewed from the axial direction, having a second deep groove 18 as an inlet / outlet groove for reverse rotation and a second shallow groove 19 as a shallow groove for reverse rotation. The shallow groove for reverse rotation in this invention may be any shallow groove having a closed end that contributes to the generation of positive pressure during reverse rotation.

[0038] The second deep groove 18 is a groove of constant depth that extends radially, with its outer diameter end 18a communicating with the outer space S2. The inner diameter end 18b of the second deep groove 18 is closed. In this embodiment, the depth of the second deep groove 18 is approximately the same as the depth of the first deep groove 16, but it may be different from the depth of the first deep groove 16.

[0039] Furthermore, the radial length of the second deep groove 18 is shorter than the radial length of the first deep groove 16. In other words, the inner diameter end 18b of the second deep groove 18 is located on the outer diameter side, or in other words, on the outer space S2 side, than the inner diameter end 16b of the first deep groove 16.

[0040] The circumferential length of the second deep groove 18 is approximately the same as the circumferential length of the first deep groove 16, but it may be different.

[0041] The second shallow groove 19 is a groove of constant depth that extends along the circumferential direction. The downstream end of the second shallow groove 19 is an open end 19a that communicates with the upstream side of the inner diameter end 18b of the second deep groove 18. The upstream end of the second shallow groove 19 is a closed end 19b. In this embodiment, the depth of the second shallow groove 19 is approximately the same as that of the first shallow groove 17, but it may be different from the depth of the first shallow groove 17.

[0042] The closed end 19b of the second shallow groove 19 overlaps radially with the closed end 17b of the first shallow groove 17. In this invention, radial overlap means being located at the same position in the circumferential direction but at different positions in the radial direction.

[0043] Although the radial length of the second shallow groove 19 is substantially the same as the radial length of the first shallow groove 17, it may be appropriately changed. Also, although the circumferential length of the second shallow groove 19 is substantially the same as the circumferential length of the first shallow groove 17, it may be appropriately changed.

[0044] The circulation groove 15 is a groove with a constant depth formed in a C shape when viewed from the axial direction. The depth of the circulation groove 15 is substantially the same as the depths of the first deep groove 16 in the release step 13 and the second deep groove 18 in the reverse release step 14. Note that the depth of the circulation groove 15 may be different from the depths of the first deep groove 16 and the second deep groove 18.

[0045] The circulation groove 15 has an upstream first radially extending portion 15a extending along the radial direction, a circumferentially extending portion 15b extending along the circumferential direction from the inner diameter end of the first radially extending portion 15a toward the downstream side, and a downstream second radially extending portion 15c extending along the radial direction from the downstream end of the circumferentially extending portion 15b toward the outer diameter side in the radial direction. The first radially extending portion 15a and the second radially extending portion 15c communicate with the outer space S2.

[0046] The first radially extending portion 15a is provided between the first deep groove 16 and the second shallow groove 19 in the circumferential direction. The circumferentially extending portion 15b is provided between the first shallow groove 17 and the reverse release step 14 in the radial direction. The second radially extending portion 15c is provided on the downstream side of the second deep groove 18.

[0047] Next, the sealing between the inner space S1 and the outer space S2 by the stationary seal ring 10 and the rotating seal ring 20 will be described using FIGS. 3 and 4. Note that the fluid flow in FIG. 3 is schematically shown assuming that the rotating seal ring 20 is rotating forward and at a low speed. Also, the fluid flow in FIG. 4 is schematically shown assuming that the rotating seal ring 20 is rotating in the reverse direction.

[0048] When the mechanical seal is not operating and the rotating seal ring 20 is not rotating, the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 are in contact. Thereby, the liquid F is prevented from flowing out into the inner space S1.

[0049] First, let's explain the operation during forward rotation at a low speed. At low speeds, immediately after the rotating sealing ring 20 begins to rotate in the forward direction relative to the stationary sealing ring 10, as shown by the white arrows in Figure 3, the gas A in the spiral groove 12 attempts to move in the direction of rotation of the rotating sealing ring 20 due to shear with the sliding surface 21.

[0050] Gas A is guided along the spiral groove 12 to the closed end 12b and supplied between the sliding surfaces 11 and 21 from the closed end 12b and its vicinity. This gas A moves mainly toward the outer diameter side and downstream side. Positive pressure is also generated at the closed end 12b and its vicinity.

[0051] As shown by the black arrows in Figure 3, the liquid F in the first shallow groove 17 in the Rayleigh step 13 is guided to the closed end 17b located downstream along the first shallow groove 17, and supplied between the sliding surfaces 11 and 21 from the closed end 17b and its vicinity. This liquid F moves mainly downstream. Also, positive pressure is generated at the closed end 17b and its vicinity.

[0052] The first shallow groove 17 can efficiently generate dynamic pressure by introducing liquid F from the first deep groove 16. Since liquid F flows into the first deep groove 16 from the outer space S2, the liquid F can be stably guided into the first shallow groove 17.

[0053] Furthermore, relative negative pressure is generated on the upstream side of the first shallow groove 17, that is, on the open end 17a side. In other words, the force that draws in the liquid F becomes stronger. Hereafter, relative negative pressure will be simply referred to as "negative pressure".

[0054] As shown by the black arrows in Figure 3, the liquid F in the second shallow groove 19 in the reverse Rayleigh step 14 is guided to the open end 19a located downstream along the second shallow groove 19 and flows into the second deep groove 18. Consequently, some of the liquid F in the second deep groove 18 flows out into the outer space S2.

[0055] Furthermore, negative pressure is generated on the upstream side of the second shallow groove 19, that is, on the closed end 19b side.

[0056] As shown by the black arrows in Figure 3, the liquid F in the circulation groove 15 is guided from the first radially extended portion 15a to the circumferentially extended portion 15b, then from the circumferentially extended portion 15b to the second radially extended portion 15c, and from the second radially extended portion 15c it is easily returned to the outer space S2. As a result, the liquid F supplied from the Rayleigh step 13 between the sliding surfaces 11 and 21 and flowing into the circulation groove 15 is easily returned to the outer space S2.

[0057] As described above, during forward rotation at low speed, the positive pressure generated by the spiral groove 12 and Rayleigh step 13 can slightly separate the sliding surfaces 11 and 21. This allows liquid F or gas A to flow between the sliding surfaces 11 and 21.

[0058] Furthermore, because the positive pressure generated in the spiral groove 12 at low speeds is small, the liquid F easily flows into the inner diameter side between the sliding surfaces 11 and 21 at low speeds. In other words, the sliding surfaces 11 and 21 are primarily lubricated by liquid, and the frictional force due to relative sliding is reduced.

[0059] Furthermore, the closed end 12b in the spiral groove 12 and the closed end 17b in the Rayleigh step 13 can generate positive pressure at different radial positions. This makes it easier to separate the sliding surfaces 11 and 21 while keeping them substantially parallel to each other.

[0060] Furthermore, since the inverted Rayleigh step 14 is located downstream of the adjacent Rayleigh step 13 in the circumferential direction, the liquid F supplied from the Rayleigh step 13 between the sliding surfaces 11 and 21 can be recovered.

[0061] Furthermore, as described above, negative pressure is generated at the closed end 19b of the second shallow groove 19, which improves the efficiency of recovering the liquid F flowing between the sliding surfaces 11 and 21.

[0062] The liquid F that has moved inward beyond the Rayleigh step 13 will now be described. The liquid F that has moved inward beyond the Rayleigh step 13 is returned towards the outer space S2 by the positive pressure generated at and near the closed end 12b of the spiral groove 12. It is also returned towards the outer space S2 by moving together with the gas A within the spiral groove 12. This reduces leakage of liquid F into the inner space S1.

[0063] Next, we will explain the operation during forward rotation and high-speed rotation. When the relative rotational speed of the rotating sealing ring 20 increases further and reaches high-speed rotation, i.e., a steady-state operation, the positive pressure generated at high speed becomes greater than the positive pressure generated at low speed.

[0064] In particular, the increased positive pressure generated by each spiral groove 12 strengthens the force pushing the liquid F back towards the outer space S2, causing the gas A to flow into the outer diameter between the sliding surfaces 11 and 21. In other words, the sliding surfaces 11 and 21 are primarily lubricated by gas, and the frictional force due to relative sliding is reduced. At this time, the sliding surfaces 11 and 21 are further apart than at low speeds, so the positive pressure due to the Rayleigh step 13 is smaller.

[0065] Next, we will explain the case when the rotating sealing ring 20 rotates in the reverse direction. Note that explanations similar to those for forward rotation will be simplified or omitted.

[0066] As shown by the white arrows in Figure 4, the gas A in the spiral groove 12 is guided along the spiral groove 12 to the open end 12a and discharged into the internal space S1. As a result, negative pressure is generated on the reverse upstream side of the spiral groove 12, that is, on the closed end 12b side.

[0067] As shown by the black arrows in Figure 4, the liquid F in the first shallow groove 17 is guided to the open end 17a located downstream along the first shallow groove 17 and flows into the first deep groove 16. Consequently, some of the liquid F in the first deep groove 16 flows out into the outer space S2.

[0068] Furthermore, negative pressure is generated on the reverse upstream side of the first shallow groove 17, that is, on the closed end 17b side.

[0069] As shown by the black arrows in Figure 4, the liquid F in the second shallow groove 19 in the reverse Rayleigh step 14 is guided along the second shallow groove 19 to the closed end 19b located on the reverse downstream side, and supplied between the sliding surfaces 11 and 21 from the closed end 19b and its vicinity. This liquid F mainly moves toward the reverse downstream side. Also, positive pressure is generated at the closed end 19b and its vicinity.

[0070] The second shallow groove 19 can efficiently generate dynamic pressure by introducing liquid F from the second deep groove 18.

[0071] Furthermore, negative pressure is generated on the reverse upstream side of the second shallow groove 19, that is, on the open end 19a side.

[0072] The liquid F in the circulation groove 15 is guided from the second radially extended portion 15c to the circumferentially extended portion 15b, then from the circumferentially extended portion 15b to the first radially extended portion 15a, and from the first radially extended portion 15a it is easily returned to the outer space S2. As a result, the liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 and flowing into the circulation groove 15 during reverse rotation is easily returned to the outer space S2.

[0073] As described above, during reverse rotation, the positive pressure generated by the reverse Rayleigh step 14 can slightly separate the sliding surfaces 11 and 21. This reduces the frictional force generated by the relative sliding of the sliding surfaces 11 and 21.

[0074] Furthermore, the closed end 19b of the reverse Rayleigh step 14 is located upstream of the first radially extended portion 15a in the circulation groove 15, and on the outer space S2 side of the circumferentially extended portion 15b.

[0075] The liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 and moving downstream flows into the first radially extended portion 15a. The liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 and moving toward the inner space S1 flows into the circumferentially extended portion 15b.

[0076] As described above, the circulation groove 15 can prevent the movement of the liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 towards the internal space S1.

[0077] Furthermore, the liquid F that flows into the circulation groove 15 is more easily guided to the outer space S2 by the shear force of the sliding surface 21. As a result, the circulation groove 15 is more effective at preventing the liquid F from moving towards the inner space S1 side of itself.

[0078] Furthermore, since the circulation groove 15 is a deep groove and has a wider flow path cross-sectional area than the shallow grooves 17 and 19, it is easier to reduce the flow velocity of the liquid F in the circulation groove 15 compared to the flow velocity of the liquid F in the shallow grooves 17 and 19. This makes it possible to more effectively inhibit the movement of the liquid F toward the internal space S1.

[0079] Furthermore, the Rayleigh step 13 has a first deep groove 16 located downstream of the first radially extended portion 15a, and a first shallow groove 17 located on the inner space S1 side of the circumferentially extended portion 15b.

[0080] Liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 and moving downstream of the circulation groove 15 flows into the first deep groove 16. Liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 and moving toward the inner space S1 side of the circulation groove 15 flows into the first shallow groove 17.

[0081] As described above, the Rayleigh step 13 is supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21, and can prevent the movement of the liquid F beyond the circulation groove 15 towards the inner space S1. In other words, the movement of the liquid F supplied from the reverse Rayleigh step 14 between the sliding surfaces 11 and 21 towards the inner space S1 can be progressively prevented by the circulation groove 15 and the Rayleigh step 13.

[0082] Furthermore, the liquid F that flows into the first shallow groove 17 is more easily guided into the first deep groove 16 by the shear force of the sliding surface 21. As a result, the Rayleigh step 13 is better able to prevent the liquid F from moving towards the inner space S1 side of itself.

[0083] Furthermore, since negative pressure is generated at the closed end 17b of the first shallow groove 17, the efficiency of recovering the liquid F that has moved beyond the circulation groove 15 to the inner space S1 is improved.

[0084] Furthermore, the first shallow groove 17 has a closed end 17b that radially overlaps with the closed end 19b of the reverse Rayleigh step 14. This improves the efficiency of recovering the high-pressure liquid F supplied between the sliding surfaces 11 and 21 from the closed end 19b and its vicinity in the reverse Rayleigh step 14 during reverse rotation.

[0085] Furthermore, the closed end 17b of the first shallow groove 17 and the closed end 12b of one spiral groove 12 overlap radially. Since negative pressure is generated at both the closed end 17b of the first shallow groove 17 and the closed end 12b of the spiral groove 12, the pressure gradient between them is small.

[0086] Furthermore, since the Rayleigh step 13 and the reverse Rayleigh step 14 are independent of each other, it is possible to prevent the dynamic pressure generated in the reverse Rayleigh step 14 and the dynamic pressure generated in the Rayleigh step 13 from interfering with each other.

[0087] In this embodiment, the communication groove has been described as a circulating groove 15 whose extension direction ends are in communication with the outer space S2, but it is not limited to this, and it may have a structure having only a first radial extension portion 15a, or a structure having a first radial extension portion 15a and a circumferential extension portion 15b, or a curved shape that follows the first radial extension portion 15a and the circumferential extension portion 15b, and the shape and arrangement may be changed as appropriate as long as it is a structure that is in communication with the outer space S2 and is provided between the Rayleigh step 13 and the closed end 19b of the reverse Rayleigh step 14.

[0088] In other words, even if the communication groove has only one end in the extension direction in communication with the outer space S2 and the other end is closed, it is possible to increase the efficiency of preventing the movement of liquid F towards the inner space S1. On the other hand, from the viewpoint of easily returning liquid F to the outer space S2 regardless of the direction of rotation, it is preferable for the communication groove to be a circulation groove, as in this embodiment.

[0089] Next, the sliding parts according to Embodiment 2 will be described with reference to Figures 5 and 6. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0090] Referring to Figure 5, the sliding surface 211 of the stationary sealing ring 210 is provided with a plurality of spiral grooves 12, a plurality of Rayleigh steps 213, a plurality of reverse Rayleigh steps 214, and a circulation groove 215.

[0091] The circulation groove 215 has a first radially extending portion 215a, a circumferentially extending portion 215b, and a second radially extending portion 215c. The closed end on the inner diameter side of the first radially extending portion 215a protrudes further inward than the circumferentially extending portion 215b and the second radially extending portion 215c.

[0092] The Rayleigh step 213 has a first radial extension 215a and a first shallow groove 217 extending downstream from the closed end of the first radial extension 215a. The first radial extension 215a also functions as a forward rotation guide groove in the Rayleigh step 213.

[0093] The inverted Rayleigh step 214 has a second radially extended portion 215c and a second shallow groove 219 extending upstream from the radial center of the second radially extended portion 215c. The second radially extended portion 215c also functions as an inlet / outlet groove for reverse rotation in the inverted Rayleigh step 214.

[0094] In other words, the Rayleigh step 213 and inverse Rayleigh step 214 in this embodiment are easier to manufacture and reduce the circumferential region required for formation, compared to the structure in which deep grooves 16 and 18 are individually provided separately from the circulation groove 15, as in the first embodiment.

[0095] During forward rotation, the liquid F supplied from the Rayleigh step 213 between the sliding surfaces 211, 21 is easily returned to the outer space S2 by flowing into the circulation groove 215.

[0096] During reverse rotation, the liquid F supplied from the reverse Rayleigh step 214 between the sliding surfaces 211, 21 is easily returned to the outer space S2 by flowing into the circulation groove 215.

[0097] Furthermore, a circumferential extension 215b is provided between the first shallow groove 217 and the second shallow groove 219 in the radial direction. This allows the circulation groove 215 and the Rayleigh step 213 to gradually inhibit the movement of the liquid F supplied from the reverse Rayleigh step 214 to the inner space S1 side during reverse rotation.

[0098] In other words, the circulation groove 215 functions as a connecting groove of the present invention, similar to the circulation groove 15 in Embodiment 1. Thus, the connecting groove of the present invention only needs to be provided, at least a portion of which is located between the closed end of the reverse rotation groove and the forward rotation groove.

[0099] Furthermore, although the Rayleigh step 213 and the reverse Rayleigh step 214 in this embodiment are in communication through the circumferentially extended portion 215b, the parts that function as lead-in / out grooves are different, so it is possible to prevent the dynamic pressure generated in the reverse Rayleigh step 214 and the dynamic pressure generated in the Rayleigh step 213 from interfering with each other. In this way, if the parts that function as lead-in / out grooves are different, the lead-in / out groove for forward rotation and the lead-in / out groove for reverse rotation are considered independent. In other words, if both the lead-in / out groove and the reverse-rotation groove are not in communication with a single lead-in / out groove, they are considered independent.

[0100] Furthermore, the circumferential length of the first shallow groove 217 is longer than the circumferential length of the second shallow groove 219. The entire second shallow groove 219 overlaps the first shallow groove 217 in the radial direction.

[0101] As a result, the first shallow groove 217 can prevent the movement of any liquid F supplied between the sliding surfaces 211, 21 from any part of the second shallow groove 219 towards the inner space S1 during reverse rotation. Therefore, the Rayleigh step 213 can more efficiently prevent the movement of liquid F supplied between the sliding surfaces 211, 21 from the reverse Rayleigh step 214 towards the inner space S1 during reverse rotation.

[0102] In addition, the regions in which the reverse rotation groove and the forward rotation groove overlap radially, such as the first shallow groove 217 and the second shallow groove 219 in this embodiment, and the first shallow groove 17 and the second shallow groove 19 in Embodiment 1, may be modified as appropriate.

[0103] Furthermore, the first radially extended portion 215a may taper toward the inner diameter, as shown in the first radially extended portion 215Aa in the circulation groove 215A, which is modified example 2-1 in Figure 6. By adopting such a structure, the amount of liquid F flowing from the outer space S2 toward the first shallow groove 217 during forward rotation can be restricted, thereby improving sealing performance, especially when the depth of the first radially extended portion 215Aa is shallow or when the relative rotation speed of the rotating sealing ring 20 is fast.

[0104] Similarly, the second radial extension portion 215c may taper toward the inner diameter, similar to the second radial extension portion 215Ac in the circulation groove 215A. This structure allows for a reduction in the amount of liquid F flowing from the outer space S2 toward the second shallow groove 219 during reverse rotation, thereby improving sealing performance, especially when the depth of the second radial extension portion 215Ac is shallow or when the relative rotation speed of the rotating sealing ring 20 is high.

[0105] Next, the sliding parts according to Embodiment 3 will be described with reference to Figure 7. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0106] Referring to Figure 7, the sliding surface 311 of the stationary sealing ring 310 is provided with a plurality of spiral grooves 12, a plurality of Rayleigh steps 313, a plurality of reverse Rayleigh steps 314, and a single circulation groove 315 that serves as a connecting groove.

[0107] The circulation groove 315 has a plurality of radially extending connecting portions 315a and a plurality of circumferentially extending portions 315b, and is connected in an annular shape.

[0108] The communication portion 315a is formed in an L-shape when viewed from the axial direction, having a closed end 315c that protrudes inward from the downstream end. The outer end of the communication portion 315a is in communication with the outer space S2 in the circumferential direction.

[0109] The circumferentially extending portion 315b is provided on a concentric circle at a position spaced further inward from the outer space S2, and communicates with two adjacent connecting portions 315a in the circumferential direction.

[0110] The Rayleigh step 313 has a connecting section 315a and a first shallow groove 317 extending downstream from the closed end 315c of the connecting section 315a. The connecting section 315a also functions as an inlet / outlet groove in the Rayleigh step 313.

[0111] The inverted Rayleigh step 314 has a connecting portion 315a and a second shallow groove 319 that extends upstream from a position on the outer diameter side of the circumferentially extending portion 315b in the connecting portion 315a. The connecting portion 315a also functions as an inlet / outlet groove in the inverted Rayleigh step 314. In other words, both the first shallow groove 317 of the Rayleigh step 313 and the second shallow groove 319 of the inverted Rayleigh step 314 are in communication with the connecting portion 315a.

[0112] During forward rotation, the liquid F supplied from the Rayleigh step 313 between the sliding surfaces 311 and 21 is easily returned to the outer space S2 by flowing into the circulation groove 315.

[0113] During reverse rotation, the liquid F supplied from the reverse Rayleigh step 314 between the sliding surfaces 311 and 21 is easily returned to the outer space S2 by flowing into the circulation groove 315.

[0114] Furthermore, a circumferentially extended portion 315b is provided between the first shallow groove 317 and the second shallow groove 319 in the radial direction. This allows the circulation groove 315 and the Rayleigh step 313 to gradually inhibit the movement of the liquid F supplied from the reverse Rayleigh step 314 to the inner space S1 side during reverse rotation.

[0115] Furthermore, the Rayleigh step 313 and the inverse Rayleigh step 314 in this embodiment share a single connecting portion 315a.

[0116] This allows the liquid F recovered in the reverse Rayleigh step 314 during forward rotation to be supplied to the Rayleigh step 313 via the communication section 315a, and the sealed fluid recovered in the Rayleigh step 313 during reverse rotation to be supplied to the reverse Rayleigh step 314, thereby increasing the dynamic pressure generation efficiency.

[0117] Furthermore, since the sliding surface 311 has a structure in which a single annular series of circulation grooves 315 are formed, it is easier to manufacture compared to the case where circulation grooves are formed individually, as in the case of multiple circulation grooves 15 in Embodiment 1.

[0118] Furthermore, since the circulation groove 315 has a long radial and circumferential length and a large surface area, it facilitates the supply of liquid F between the sliding surfaces 311 and 21.

[0119] Furthermore, the circumferential length of the first shallow groove 317 is longer than the circumferential length of the second shallow groove 319. The entire second shallow groove 319 overlaps radially with the first shallow groove 317. As a result, the Rayleigh step 313, similar to Embodiment 2, can more efficiently inhibit the movement of the liquid F supplied from the reverse Rayleigh step 314 to the inner space S1 side when rotating in the reverse direction.

[0120] Next, the sliding parts according to Embodiment 4 will be described with reference to Figures 8 and 9. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0121] Referring to Figure 8, the sliding surface 411 of the stationary sealing ring 410 is provided with a plurality of spiral grooves 412 (72 in this embodiment), six sets of Rayleigh steps 13, six sets of reverse Rayleigh steps 14, and six circulation grooves 15.

[0122] The multiple spiral grooves 412 have different lengths in the extension direction from the open end 412a to the closed end 412b. The multiple spiral grooves 412 are arranged so that each closed end 412b traces a sinusoidal contour. However, the contour traced by each closed end 412b may be a wave shape other than a sinusoidal one.

[0123] Of the multiple spiral grooves 412, the spiral groove 412L with the longest extension length has its closed end 412b overlap radially with the circumferential center of the second shallow groove 19. The other spiral grooves 412 have shorter radial lengths as they move away from spiral groove 412L in the circumferential direction. The spiral groove 412S with the shortest extension length of the multiple spiral grooves 412 is located in the center of the circumferential distance between the Rayleigh step 13 and the reverse Rayleigh step 14 located upstream of it.

[0124] In other words, spiral grooves 412 that do not radially overlap with Rayleigh steps 13 or inverse Rayleigh steps 14 are shorter than spiral grooves 412 that radially overlap with Rayleigh steps 13 or inverse Rayleigh steps 14. As a result, the negative pressure generated in the spiral grooves 412 has less effect on the liquid F that moves downstream of Rayleigh steps 13 during reverse rotation, thus further reducing leakage of liquid F during reverse rotation.

[0125] It should be noted that the multiple dynamic pressure generating grooves are not limited to the multiple spiral grooves 412 in this embodiment, and may have only two lengths in the extending direction, as shown in the multiple spiral grooves shown as Modification 4-1 in Figure 9. In Modification 4-1 shown in Figure 9, multiple long spiral grooves 412L that radially overlap with the Rayleigh step 13 and reverse Rayleigh step 14, and multiple short spiral grooves 412S that do not radially overlap with the Rayleigh step 13 and reverse Rayleigh step 14 are shown. Even with such a configuration, leakage of liquid F during reverse rotation can be further reduced.

[0126] On the other hand, from the viewpoint of easily increasing the positive pressure generated by the spiral grooves during forward rotation, a configuration in which the radial length of the spiral grooves is shortened as they move circumferentially away from the Rayleigh steps 13 and reverse Rayleigh steps 414, as in the multiple spiral grooves 412 of this embodiment, is preferable.

[0127] Next, the sliding parts according to Embodiment 5 will be described with reference to Figure 10. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.

[0128] Referring to Figure 10, in this embodiment, the inner space S51 is a sealed fluid space where liquid F is present, and the outer space S52 is a leak space where gas A is present. In other words, the mechanical seal in this embodiment is of the outside type.

[0129] The sliding surface 511 of the stationary sealing ring 510 is provided with 24 spiral grooves 512, 3 sets of Rayleigh steps 513, 3 sets of reverse Rayleigh steps 514, and 3 circulation grooves 515.

[0130] The spiral groove 512 communicates with the outer space S52 and extends inclined toward the downstream and inner diameter side.

[0131] Furthermore, the Rayleigh step 513 has a first deep groove 516 that communicates with the internal space S51 and extends radially outward, and a first shallow groove 517 that extends downstream from the outer diameter end of the first deep groove 516.

[0132] Furthermore, the inverted Rayleigh step 514 has a second deep groove 518 that communicates with the internal space S51 and extends radially outward, and a second shallow groove 519 that extends upstream from the outer diameter end of the second deep groove 518.

[0133] The circulation groove 515 has radially extended portions 515a and 515c that communicate with the outer space S2, and circumferentially extended portions 515b that communicate with the outer diameter ends of the radially extended portions 515a and 515c, respectively.

[0134] As a result, during forward rotation, the spiral groove 512 and Rayleigh step 513 generate positive pressure, slightly separating the sliding surfaces 511 and 21 and reducing frictional force. In addition, the positive pressure generated by the spiral groove 512 can return the liquid F to the inner space S1.

[0135] During reverse rotation, the reverse Rayleigh step 514 generates positive pressure, slightly separating the sliding surfaces 511 and 21 and reducing frictional force. In addition, the circulation groove 515 and Rayleigh step 513 can obstruct the flow of liquid F supplied from the reverse Rayleigh step 514 to the sliding surfaces 511 and 21 towards the outer space S52.

[0136] In other words, the sliding component of the present invention can exhibit its effects even when applied to an outside-type mechanical seal.

[0137] 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.

[0138] For example, in the above embodiments 1 to 5, the configuration was described as having a liquid in the sealed fluid-side space, but it is not limited to this; it may also be a gas, or a mist-like mixture of liquid and gas. The same applies to the leak-side space. In other words, the same fluid may be present in both the sealed fluid-side space and the leak-side space.

[0139] Furthermore, while embodiments 1 to 5 above illustrate configurations where the gas is at a lower pressure than the liquid, the liquid may be at a lower pressure and the gas at a higher pressure, or the liquid and gas may be at approximately the same pressure.

[0140] Furthermore, although one of the sliding surfaces was described as the sliding surface of a stationary sealing ring in Examples 1 to 5 above, it is not limited to this and may be the sliding surface of a rotating sealing ring.

[0141] Furthermore, although the dynamic pressure generating groove was described as a spiral groove in the above embodiments 1 to 5, it is not limited to this, and may be an inclined groove extending linearly toward the closed end, or a so-called herringbone-shaped groove that extends from the leakage space side toward the sealed fluid space side and downstream, and then bends toward the sealed fluid space side and upstream, or a Rayleigh step, and may be modified as appropriate.

[0142] On the other hand, spiral grooves, inclined grooves, or herringbone-shaped grooves are preferable to Rayleigh step grooves in terms of ensuring a wide area where positive pressure is generated by densely arranging grooves in the circumferential direction. Also, spiral grooves or inclined grooves are preferable to herringbone-shaped grooves in terms of being less likely to suck in liquid during forward rotation. Furthermore, spiral grooves are preferable to inclined grooves in terms of ensuring sufficient volume per groove and making it easier to increase positive pressure.

[0143] Furthermore, although the spiral grooves in embodiments 1 to 5 were described as being in communication with the leakage space, the invention is not limited to this and may not be in communication with it. In other words, the dynamic pressure generating grooves may not be in communication with the leakage space. On the other hand, from the viewpoint of easily increasing the dynamic pressure generation efficiency during forward rotation and easily suppressing leakage during reverse rotation, it is preferable for the grooves to be in communication with the leakage space.

[0144] Furthermore, although it was explained in the above embodiments 1 to 5 that the spiral groove is provided on the leakage space side of the Rayleigh step, the invention is not limited to this, and the spiral groove may overlap the Rayleigh step in the circumferential direction.

[0145] In other words, in the dynamic pressure generating groove of the present invention, "located on the leakage space side" means that at least a portion of the dynamic pressure generating groove is located on the leakage space side than the forward rotation groove and the reverse rotation groove. The same applies to the forward rotation groove and the reverse rotation groove, and in these, "located on the sealed fluid space side" means that at least a portion of the forward rotation groove or at least a portion of the reverse rotation groove is located on the sealed fluid space side than the dynamic pressure generating groove.

[0146] On the other hand, from the viewpoint of reducing leakage during reverse rotation, it is preferable that the spiral groove be located on the leakage side of the Rayleigh step, that is, that the spiral groove and the Rayleigh step do not overlap in the circumferential direction.

[0147] Furthermore, although the forward rotation groove was described as a Rayleigh step in Examples 1 to 5 above, it is not limited to this, and may also be a spiral groove or inclined groove extending from the sealed fluid space side to the forward rotation side and the leakage space side, and may be modified as appropriate.

[0148] Furthermore, although the Rayleigh step was described in Examples 1 to 5 as having a structure that communicates with the sealed fluid space, it is not limited to this and may not communicate with it. In other words, the forward rotation groove may not communicate with the sealed fluid space. On the other hand, from the viewpoint of easily increasing the dynamic pressure generation efficiency during forward rotation, it is preferable that it communicates with the sealed fluid space.

[0149] Furthermore, although the reverse rotation groove was described as a reverse Rayleigh step in Examples 1 to 5, it is not limited to this, and may also be a spiral groove or inclined groove extending from the sealed fluid space side to the reverse rotation side and leak space side, and may be modified as appropriate.

[0150] Furthermore, although the reverse Rayleigh step was described in Examples 1 to 5 as having a structure that communicates with the sealed fluid space, it is not limited to this and may not communicate with it. In other words, the reverse rotation groove may not communicate with the sealed fluid space. On the other hand, from the viewpoint of easily increasing the efficiency of dynamic pressure generation during reverse rotation, it is preferable that it communicates with the sealed fluid space.

[0151] Furthermore, while mechanical seals were used as examples of sliding parts in Examples 1 to 5, the invention is not limited to mechanical seals, and thrust bearings, radial bearings, plain bearings, etc., may also be used.

[0152] 1 Rotating shaft 4 Housing 10 Stationary sealing ring 11 Sliding surface (one sliding surface) 12 Spiral groove (dynamic pressure generating groove) 13 Rayleigh step (groove for forward rotation) 14 Reverse Rayleigh step (groove for reverse rotation) 15 Circulation groove (communication groove) 16 First deep groove (inlet / outlet groove for forward rotation) 17 First shallow groove (shallow groove for forward rotation) 18 Second deep groove (inlet / outlet groove for reverse rotation) 19 Second shallow groove (shallow groove for reverse rotation) 20 Rotating sealing ring 21 Sliding surface (the other sliding surface) S1 Inner space (leakage space) S2 Outer space (space of sealed fluid)

Claims

1. A sliding component comprising a pair of sliding surfaces arranged at a location where they rotate relative to each other, thereby separating a leak space from a sealed fluid space, wherein one of the sliding surfaces comprises a dynamic pressure generating groove located on the leak space side and extending in the forward rotation direction of the relative rotation, a forward rotation groove located on the sealed fluid space side and extending in the forward rotation direction of the relative rotation, and a reverse rotation groove located on the sealed fluid space side and extending in the reverse rotation direction of the relative rotation, wherein the closed end of the reverse rotation groove is provided on the sealed fluid space side than the forward rotation groove, and a communication groove communicating with the sealed fluid space is provided between the reverse rotation groove and the forward rotation groove.

2. The sliding component according to claim 1, wherein the reverse rotation groove and the forward rotation groove overlap radially.

3. The sliding part according to claim 2, wherein the forward rotation groove has a shallow forward rotation groove extending toward the forward rotation side in the relative rotation direction, the reverse rotation groove has a shallow reverse rotation groove extending toward the reverse rotation side in the relative rotation direction, and the entire reverse rotation shallow groove overlaps the forward rotation shallow groove in the radial direction.

4. The forward rotation groove has a forward rotation shallow groove extending toward the forward rotation side in the relative rotation direction and a forward rotation outlet / inlet groove communicating with the sealed fluid space, and the reverse rotation groove has a reverse rotation shallow groove extending toward the reverse rotation side in the relative rotation direction and a reverse rotation outlet / inlet groove communicating with the sealed fluid space, and the forward rotation outlet / inlet groove and the reverse rotation outlet / inlet groove are independent of each other, as described in any one of claims 1 to 3.

5. The sliding part according to any one of claims 1 to 3, wherein the forward rotation groove has a shallow forward rotation groove extending toward the forward rotation side in the relative rotation direction, the reverse rotation groove has a shallow reverse rotation groove extending toward the reverse rotation side in the relative rotation direction, the forward rotation groove and the reverse rotation groove share an inlet / outlet groove that communicates with the sealed fluid space, and the forward rotation shallow groove and the reverse rotation shallow groove communicate with the inlet / outlet groove.

6. The sliding component according to claim 1, wherein the dynamic pressure generating groove is a plurality of spiral grooves communicating with the leakage space.

7. The sliding component according to claim 6, wherein the spiral groove that does not overlap radially with the forward rotation groove is shorter than the other spiral grooves.

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