Sliding parts
The sliding component design addresses leakage issues in mechanical seals by utilizing overlapping grooves to manage fluid flow during reverse rotation, enhancing leakage prevention and dynamic pressure efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- EAGLE INDS
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026112864000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to sliding parts that rotate relative to each other, and is used, for example, as a sliding part for a shaft sealing device that seals the rotating shaft of a rotating machine in the field of automobiles, general industrial machinery, or other sealing fields, or as a sliding part used for a bearing of a machine in the field of automobiles, general industrial machinery, or other bearings.
Background Art
[0002] As a sliding part 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 some sliding surfaces of the sliding rings are provided with dynamic pressure grooves.
[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 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 groove portion extending along the circumferential direction from the outer diameter end of the liquid guiding groove portion toward the reverse rotation side.
[0005] During forward rotation of the rotating sealing ring, the Rayleigh step guides the incoming sealed fluid toward the closed end on the forward rotation side of the forward-direction groove, generating positive pressure at and near this closed end. Similarly, in the dynamic pressure generating groove, the incoming air is guided toward the closed end on the inner diameter side, introducing the sealed fluid in the internal space into the liquid guide groove, generating positive pressure at and near this closed end. Thus, during forward rotation, the positive pressure generated in the Rayleigh step and the dynamic pressure generating groove causes a slight separation between the sliding surfaces, thereby reducing frictional force.
[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. [Prior art documents] [Patent Documents]
[0007] [Patent Document 1] International Publication No. 2023 / 223914 (pp. 8-10, Figure 3) [Overview of the project] [Problems that the invention aims to solve]
[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. [Means for solving the problem]
[0010] To solve the aforementioned problems, the sliding component of the present invention is A sliding component in which a pair of sliding surfaces are positioned at a location where they rotate relative to each other, thereby separating a leak space from a fluid space to be sealed, One of the sliding surfaces comprises a dynamic pressure generating groove located on the leakage space side and extending in the forward rotation direction of the relative rotation, a plurality of forward rotation grooves 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, The reverse closing end of the reverse rotation groove is provided on the side of the sealed fluid space that is closer than the forward rotation groove. The positive closing end of the upstream positive rotation groove overlaps radially with at least a portion of the downstream positive rotation groove on the leakage space side. According to this, when rotating in reverse, the upstream forward rotation groove, which is positioned on the leak side of at least a portion of the reverse-closing end and the downstream forward rotation groove, can prevent the movement of the sealed fluid that has flowed out from the reverse-closing end and the downstream forward rotation groove into the leak space, thereby reducing leakage.
[0011] The forward rotation groove has a radial portion and a circumferential portion having the forward closed end, The positive closing end of the upstream positive rotation groove may overlap radially with at least a portion of the radial portion of the downstream positive rotation groove. According to this, the area required for forming grooves for forward rotation can be narrowed.
[0012] The forward rotation groove has a radial portion and a circumferential portion having the forward closed end, The positive closing end of the upstream positive rotation groove may overlap radially with at least a portion of the circumferential portion of the downstream positive rotation groove. According to this, it becomes easier to allow the sealed fluid flowing out from the radial portion or the circumferential portion of the forward rotation groove on the downstream side during reverse rotation to flow into the positive circumferential portion of the forward rotation groove on the upstream side.
[0013] At least a part of the radial portion may be inclined toward the positive circumferential portion. According to this, it becomes easier to generate a flow toward the sealed fluid space side by the sealed fluid flowing from the positive circumferential portion into the radial portion during reverse rotation, so that the sealed fluid moving from the radial portion to the leakage space side can be reduced.
[0014] The forward rotation groove and the reverse rotation groove share the radial portion. The reverse rotation groove may have a reverse circumferential portion having the reverse closing end. According to this, since the sealed fluid flowing into the forward rotation groove during reverse rotation can be supplied to the reverse closing end, the dynamic pressure generation efficiency can be increased.
[0015] The dynamic pressure generation groove may be a plurality of spiral grooves communicating with the leakage space. According to this, the leakage of the sealed fluid during forward rotation can be reduced.
[0016] Some of the spiral grooves may be shorter than the other spiral grooves. According to this, the leakage of the sealed fluid during reverse rotation can be further reduced.
Brief Description of the Drawings
[0017] [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 seen from the axial direction. [Figure 3] It is an enlarged view of the main part of FIG. 2 during forward rotation. [Figure 4] It is an enlarged view of the main part of FIG. 2 during reverse rotation. [Figure 5]It is an enlarged view of the main part of the sliding surface of the stationary seal ring in Example 2 according to the present invention. [Figure 6] It is an enlarged view of the main part of the sliding surface of the stationary seal ring in Example 3 according to the present invention. [Figure 7] It is an enlarged view of the main part of the sliding surface of the stationary seal ring in Example 4 according to the present invention. [Figure 8] It is an enlarged view of the main part of the sliding surface of the stationary seal ring in Example 5 according to the present invention. [Figure 9] It is a view of the stationary seal ring in Example 6 according to the present invention as seen from the axial direction. [Figure 10] It is a view of the stationary seal ring in Example 7 according to the present invention as seen from the axial direction. [Figure 11] It is a view of the stationary seal ring in Example 8 according to the present invention as seen from the axial direction. [Figure 12] It is a view of the stationary seal ring in Modified Example 8-1 of Example 8 as seen from the axial direction. [Figure 13] It is a view of the stationary seal ring in Example 9 according to the present invention as seen from the axial direction.
Embodiments for Carrying Out the Invention
[0018] Embodiments for carrying out the sliding parts according to the present invention will be described below based on examples.
Examples
[0019] The sliding parts according to Example 1 will be described with reference to FIGS. 1 to 4. In this example, a mechanical seal is taken as an example of the sliding parts for explanation. Also, for the sake of convenience of explanation, dots may be added to the grooves formed on the sliding surface in the drawings.
[0020] The mechanical seal shown in Figure 1 separates an inner space S1, which is a leak 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 where 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 mounted 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 this. 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 area clockwise from the position of the object will be described as the upstream side in the forward rotation direction, and the area counterclockwise from the position of the object will be described as the downstream side in the forward rotation direction. In reverse rotation, the area clockwise from the position of the object will be described as the downstream side in the reverse rotation direction, and the area 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, 30 sets of forward rotation grooves 13, and 30 sets of reverse rotation grooves 14. On the sliding surface 11, the parts other than the spiral grooves 12, forward rotation grooves 13, and reverse rotation grooves 14 form flat lands 15.
[0027] Although the 24 spiral grooves 12 are equally spaced, their number and arrangement may be changed as appropriate. The same applies to the 30 sets of forward rotation grooves 13 and the 30 sets of reverse rotation grooves 14.
[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 inclined from the open end 12a toward the outer diameter side and toward the downstream side in the forward rotation direction. 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 depth of the spiral groove 12, i.e., its axial length, is approximately constant from the open end 12a to the closed end 12b, but it may change so that it becomes shallower from the open end 12a to the closed end 12b. Furthermore, the cross-sectional shape of the spiral groove 12 is rectangular, but it may also be semicircular or triangular, and may be changed as appropriate. These depth and cross-sectional shapes also apply to the forward rotation groove 13 and the reverse rotation groove 14.
[0031] The forward rotation groove 13 is formed in an L-shape that is inverted left and right when viewed from the axial direction, having a radial portion 16 and a circumferential portion 17, and functions as a so-called Rayleigh step. In this invention, the forward rotation groove only needs to have a positive closing end that contributes to the generation of positive pressure during forward rotation.
[0032] The radial section 16 is a deep groove of constant depth extending in the radial direction, with its outer diameter end 16a communicating with the outer space S2. The inner diameter end 16b of the radial section 16 is closed. The depth of the radial section 16 is greater than that of the spiral groove 12.
[0033] Of the sides defining the radial portion 16, the upstream side facing the inner diameter end 16b is an inclined surface 16c that extends inclined from the outer diameter side towards the inner diameter side and downstream side, that is, toward the circumferential portion 17. The other sides extend along the radial direction. The inclined surface 16c is continuous with the upstream end of the inner diameter side 17d in the circumferential portion 17, which will be described later.
[0034] The circumferential portion 17 is a shallow groove of constant depth that extends along the circumferential direction. The upstream end of the circumferential portion 17 is a positively open end 17a that communicates with the downstream side of the inner diameter end 16b of the radial portion 16. The downstream end of the circumferential portion 17 is a positively closed end 17b that is closed. The depth of the circumferential portion 17 is slightly shallower than that of the spiral groove 12 and shallower than that of the radial portion 16.
[0035] The depth of the radial section may be changed as appropriate. It may be a groove of the same depth as the circumferential section 17, a groove shallower than the circumferential section 17, a groove of the same depth as the spiral groove 12, or a groove shallower than the spiral groove 12. On the other hand, a deeper radial section is preferable from the viewpoint of retaining liquid F and preventing poor lubrication. Similarly, the depths of the dynamic pressure generating groove, the forward rotation groove, and the reverse rotation groove 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 the groove is composed of multiple parts, as in the forward rotation groove 13 of this embodiment, the depth of each part may be set individually.
[0037] Of the sides defining the circumferential portion 17, the outer diameter side facing the positive closed end 17b is an inclined surface 17c that extends inclined from the outer diameter side toward the inner diameter side and downstream side. The other sides extend along the circumferential direction. Of these, the inner diameter side 17d is continuous with the inner diameter end of the inclined surface 17c.
[0038] The inclined surface 17c overlaps radially and circumferentially with the inclined surface 16c of the adjacent downstream radial section 16. In this invention, radial overlap means being located at the same position in the circumferential direction but at different positions in the radial direction.
[0039] The reverse rotation groove 14 is formed in an L-shape when viewed from the axial direction, having a radial portion 16 and a reverse circumferential portion 18, and functions as a so-called reverse Rayleigh step. In other words, the forward rotation groove 13 and the reverse rotation groove 14 in this embodiment share the radial portion 16. Note that the reverse rotation groove of the present invention only needs to have a reverse closed end that contributes to the generation of positive pressure during reverse rotation.
[0040] The reverse circumferential portion 18 is a shallow groove of constant depth extending along the circumferential direction, and is located on the outer diameter side of the forward circumferential portion 17. In this embodiment, the depth of the reverse circumferential portion 18 is approximately the same as that of the forward circumferential portion 17, but it may be different from the depth of the forward circumferential portion 17.
[0041] The reverse circumferential portion 18 has a shorter circumferential length than the forward circumferential portion 17 and is provided between two adjacent radial portions 16 in the circumferential direction. The entire reverse circumferential portion 18 overlaps radially with the adjacent upstream forward circumferential portion 17.
[0042] The upstream end of the reverse circumferential section 18 is a closed reverse closed end 18a, which is located downstream of the adjacent upstream radial section 16. The downstream end of the reverse circumferential section 18 is a closed reverse open end 18b, which communicates with the upstream side of the radial center of the radial section 16.
[0043] Next, the sealing between the inner space S1 and the outer space S2 by the stationary sealing ring 10 and the rotating sealing ring 20 will be explained using Figures 3 and 4. Note that the fluid flow in Figure 3 is schematically shown assuming the rotating sealing ring 20 is rotating in the forward direction at a low speed. Similarly, the fluid flow in Figure 4 is schematically shown assuming the rotating sealing ring 20 is rotating in the reverse direction.
[0044] When the rotating sealing ring 20 is not rotating and the mechanical seal is inactive, the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 are in contact. This prevents the liquid F from flowing out into the internal space S1.
[0045] 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.
[0046] Gas A is guided along the spiral groove 12 to the closed end 12b, and flows out between the sliding surfaces 11 and 21 from the closed end 12b and its vicinity. Positive pressure is also generated at the closed end 12b and its vicinity.
[0047] Gas A flowing out from the closed end 12b and its vicinity moves mainly toward the outer diameter and downstream side, thus pushing back liquid F that is trying to move toward the inner diameter side. In addition, liquid F that flows into the spiral groove 12 moves together with gas A and is returned toward the outer space S2. As a result, leakage of liquid F into the inner space S1 can be reduced.
[0048] As shown by the black arrows in Figure 3, the liquid F in the circumferential portion 17 of the forward rotation groove 13 is guided to the forward closure end 17b located downstream along the circumferential portion 17, and flows out between the sliding surfaces 11 and 21 from the forward closure end 17b and its vicinity. Positive pressure is also generated at the forward closure end 17b and its vicinity.
[0049] The circumferential portion 17 can efficiently generate dynamic pressure by introducing liquid F from the radial portion 16 with which it is in communication. Since liquid F flows into the radial portion 16 from the outer space S2, it can stably guide the liquid F to the circumferential portion 17. In addition, the inclined surface 16c of the radial portion 16 facilitates the guidance of liquid F within the radial portion 16 to the circumferential portion 17.
[0050] Furthermore, the liquid F that flows out from the positive closure end 17b and its vicinity mainly moves downstream and flows into the downstream radial section 16, which overlaps with the positive closure end 17b in both the radial and circumferential directions. Along with this inflow, some of the liquid F in the radial section 16 flows out into the outer space S2.
[0051] Because the radial section 16 is a deep groove, it can reduce the flow velocity and dynamic pressure of the liquid F that flows out from the upstream positive closure end 17b and its vicinity and flows into it compared to before the flow. This prevents the increased dynamic pressure and flow velocity of the liquid F in the upstream positive circumferential section 17 from affecting the dynamic pressure and flow velocity of the liquid F in the downstream positive circumferential section 17. Furthermore, it prevents the liquid F that flows out from the positive closure end 17b and its vicinity between the sliding surfaces 11 and 21 from exceeding the radial section 16.
[0052] Thus, from the viewpoint of easily reducing the flow velocity and dynamic pressure of the liquid F, the radial portion 16 is preferably deeper than the forward circumferential portion 17 and the reverse circumferential portion 18, and its depth may be appropriately changed if it is possible to reduce the flow velocity and dynamic pressure. More preferably, it is about 5 to 50 times the depth of the forward and reverse closure ends that contribute to the generation of positive pressure.
[0053] Furthermore, the liquid F that flows out from the circumferential portion 17 toward the outer diameter flows into the downstream reverse circumferential portion 18 which overlaps radially with the circumferential portion 17. Also, the liquid F that flows out from the radial portion 16 toward the downstream side flows into the downstream radial portion 16 and the reverse circumferential portion 18 which overlap circumferentially with the radial portion 16.
[0054] As described above, the reverse rotation groove 14 facilitates the flow of liquid F that has flowed out from the upstream forward rotation groove 13 adjacent to it in the circumferential direction between the sliding surfaces 11 and 21.
[0055] Furthermore, relative negative pressure is generated on the upstream side of the circumferential portion 17, that is, on the side of the positive opening end 17a. In other words, the force drawing in the liquid F becomes stronger. Hereafter, relative negative pressure will be simply referred to as "negative pressure".
[0056] As shown by the black arrow in Figure 3, the liquid F in the reverse circumferential portion 18 of the reverse rotation groove 14 is guided to the reverse opening end 18b located downstream along the reverse circumferential portion 18 and flows into the radial portion 16. As described above, since the radial portion 16 is a deep groove, it is possible to prevent the liquid F that has flowed in from the reverse circumferential portion 18, which is in communication with it, from overflowing the radial portion 16.
[0057] Furthermore, negative pressure is generated on the upstream side of the reverse circumferential portion 18, that is, on the reverse closed end 18a side. This negative pressure makes it easier to draw in the liquid F that has flowed out from the forward rotation groove 13 on the upstream side.
[0058] As described above, during forward rotation at low speed, the positive pressure generated by the spiral groove 12 and the forward rotation groove 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.
[0059] 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.
[0060] Furthermore, the closed end 12b of the spiral groove 12 and the positive closed end 17b of the forward rotation groove 13 can generate positive pressure at different radial positions. This makes it easier to separate the sliding surfaces 11 and 21 while keeping them approximately parallel to each other.
[0061] 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.
[0062] 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 from the forward rotation groove 13 is smaller.
[0063] 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.
[0064] 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.
[0065] As shown by the black arrows in Figure 4, the liquid F in the circumferential section 17 is guided to the positively open end 17a located downstream along the circumferential section 17 and flows into the radial section 16. As described above, since the radial section 16 is a deep groove, it is possible to prevent the liquid F that flows in from the circumferential section 17, which is in communication with it, from overflowing the radial section 16. In addition, as the liquid F flows in, some of the liquid F in the radial section 16 flows out into the outer space S2. Furthermore, negative pressure is generated on the upstream side of the circumferential section 17, that is, on the positively closed end 17b side.
[0066] The liquid F that flows from the circumferential portion 17 into the radial portion 16 is easily guided toward the outer diameter by the inclined surface 16c. As a flow toward the outer diameter occurs at the inner diameter end 16b, the liquid F in the radial portion 16 is more easily returned to the outer space S2, and it becomes less likely for it to flow directly from the inner diameter end 16b between the sliding surfaces 11 and 21. In other words, the amount of liquid F that moves from the radial portion 16 toward the inner space S1 can be reduced.
[0067] As shown by the black arrows in Figure 4, the liquid F in the reverse circumferential portion 18 of the reverse rotation groove 14 is guided to the reverse closed end 18a located on the reverse downstream side along the reverse circumferential portion 18, and flows out between the sliding surfaces 11 and 21 from the reverse closed end 18a and its vicinity. This liquid F mainly moves toward the reverse downstream side and flows into the reverse downstream radial portion 16 which overlaps the reverse closed end 18a in the circumferential direction. Positive pressure is generated at the reverse closed end 18a and its vicinity. Negative pressure is generated on the reverse upstream side of the reverse circumferential portion 18, i.e., on the reverse open end 18b side.
[0068] The reverse circumferential section 18 can efficiently generate dynamic pressure by introducing liquid F from the radial section 16. Since liquid F flows into the radial section 16 from the outer space S2, it can stably guide the liquid F to the reverse circumferential section 18. In addition, the radial section 16 is designed so that the inclined surface 16c makes it easier to guide the liquid F that flows in from the normal circumferential section 17 to the reverse circumferential section 18, which is located on the outer diameter side and reverse downstream side of the normal circumferential section 17.
[0069] Similar to the forward rotation, the radial section 16 can reduce the flow velocity and dynamic pressure of the liquid F that flows into it from the reverse-upstream reverse-closed end 18a compared to before inflow, thereby preventing it from affecting the dynamic pressure and flow velocity of the liquid F in the reverse-downstream reverse-circumferential section 18. In addition, it can reduce the amount of liquid F that flows directly from the radial section 16 between the sliding surfaces 11 and 21.
[0070] Furthermore, the liquid F that flows out from the reverse circumferential section 18 toward the inner diameter flows into the reverse downstream circumferential section 17, which overlaps the reverse circumferential section 18 radially. Also, the liquid F that flows out from the radial section 16 toward the reverse downstream or inner diameter flows into the reverse downstream radial section 16 and the reverse circumferential section 17, which overlap the radial section 16 radially or circumferentially.
[0071] As described above, the forward rotation groove 13 facilitates the flow of liquid F that has flowed out from the adjacent reverse rotation groove 14 on the reverse upstream side between the sliding surfaces 11 and 21. In other words, the forward rotation groove 13 can obstruct the flow of liquid F from the adjacent reverse rotation groove 14 on the reverse upstream side toward the inner diameter in the circumferential direction.
[0072] Furthermore, as described above, the liquid F that flows into the circumferential portion 17 is easily guided to the radial portion 16. This makes it easier for the forward rotation groove 13 to prevent the liquid F from moving towards the inner space S1 side of itself.
[0073] Furthermore, as described above, negative pressure is generated at the positive closure end 17b of the forward rotation groove 13, which improves the efficiency of sucking in the liquid F that flows out from the reverse upstream radial section 16 to the reverse downstream side.
[0074] In particular, the inner diameter end 16b of the radial section 16 has a shorter circumferential length, i.e., groove width, toward the inner diameter, and there is a possibility of liquid F flowing out from the circumferential section 17. The reverse downstream positive closure end 17b overlaps with this inner diameter end 16b in both the radial and circumferential directions. In addition, the inclined surfaces 16c and 17c of the end 16b and the positive closure end 17b are parallel, which increases the efficiency of sucking up the liquid F that has flowed out from the inner diameter end 16b. In other words, leakage is reduced more easily.
[0075] As described above, during reverse rotation, the positive pressure generated by the reverse rotation groove 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.
[0076] As described above, the mechanical seal of this embodiment can reduce leakage because, during reverse rotation, the reverse-downstream forward rotation groove 13, which is located on the inner diameter side of the reverse-downstream forward rotation groove 13, can prevent the liquid F that has flowed out from the reverse-downstream forward rotation groove 13 from moving into the inner space S1.
[0077] Furthermore, the positive closing end 17b of the reverse-downstream positive rotation groove 13 overlaps radially with the radial portion 16 of the reverse-upstream positive rotation groove 13. This makes it easier for the liquid F that flows out from the radial portion 16 of the reverse-upstream positive rotation groove 13 during reverse rotation to flow into the positive circumferential portion 17 of the reverse-downstream positive rotation groove 13.
[0078] Furthermore, the positive closing end 17b of the positive circumferential portion 17 in the positive rotation groove 13 overlaps not only radially but also circumferentially with the inner diameter end 16b of the radial portion 16 in the adjacent upstream positive rotation groove 13. This allows for a narrower area to be provided for the positive rotation groove 13. As a result, for example, a wider area can be secured for providing the inner diameter spiral groove 12.
[0079] Furthermore, the inclined surface 16c in the radial section 16 and the inner diameter side surface 17d in the circumferential section 17 are continuous. This makes it easier to smoothly guide the liquid F from the circumferential section 17 to the radial section 16 during reverse rotation, thereby reducing the amount of liquid F that flows directly out from the positive opening end 17a of the circumferential section 17. Also, it makes it easier to smoothly guide the liquid F from the radial section 16 to the circumferential section 17 during forward rotation.
[0080] Although it has been explained that the radial portion 16 is inclined toward the circumferential portion only on the side facing the inner diameter end, this is not limited to this, and for example, the radial portion itself may be inclined toward the circumferential portion, and this may be changed as appropriate. In other words, the radial portion of the present invention only needs to extend mainly in the radial direction. Also, the forward circumferential portion and the reverse circumferential portion of the present invention only need to extend mainly in the circumferential direction.
[0081] Furthermore, the inner diameter side surface 17d may also face the inner diameter end of the radial section. With this configuration, a region can be secured in the radial section, which is a deep groove, where the liquid F moves toward the reverse downstream side during reverse rotation, making it easier to reduce leakage.
[0082] Furthermore, the forward rotation groove 13 and the reverse rotation groove 14 share the same radial section 16. This allows the liquid F that flows into the forward rotation groove 13 during reverse rotation to be supplied to the reverse closure end 18a, thereby increasing the efficiency of dynamic pressure generation.
[0083] Furthermore, since the dynamic pressure generating grooves are multiple spiral grooves 12 that communicate with the internal space S1, leakage of liquid F during forward rotation can be reduced.
[0084] Furthermore, the positive closing end 17b of the forward rotation groove 13 and the closing end 12b of one of the spiral grooves 12 overlap radially. Since negative pressure is generated at both the positive closing end 17b and the closing end 12b during reverse rotation, the pressure gradient between them becomes smaller. As a result, the negative pressure generated at the closing end 12b of the forward rotation groove 13 makes it easier to prevent the liquid F in the radial portion 16 of the forward rotation groove 13 on the reverse upstream side from being directly drawn into the spiral groove 12. [Examples]
[0085] Next, the sliding parts according to Example 2 will be described with reference to Figure 5. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.
[0086] 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 as grooves for forward rotation, and a plurality of reverse Rayleigh steps 214 as grooves for reverse rotation.
[0087] The Rayleigh step 213 has a radial portion 216 and a circumferential portion 217 having a positive closed end 217b. The reverse Rayleigh step 214 has a reverse circumferential portion 218 having a reverse closed end 218b and a radial portion 219.
[0088] Since the radial portion 216 of the Rayleigh step 213 and the radial portion 219 of the inverse Rayleigh step 214 are independent, it is possible to prevent the dynamic pressure generated in the Rayleigh step 213 and the dynamic pressure generated in the inverse Rayleigh step 214 from interfering with each other.
[0089] The entire inverted Rayleigh step 214 overlaps radially with the circumferential portion 217 of the adjacent upstream Rayleigh step 213. Even with this configuration, when rotating in reverse, the liquid F that flows out from the inverted Rayleigh step 214 between the sliding surfaces 211, 21 flows into the adjacent reverse downstream Rayleigh step 213, making it easier to obstruct its movement toward the inner space S1. [Examples]
[0090] Next, the sliding parts according to Embodiment 3 will be described with reference to Figure 6. Note that descriptions of components that are identical to those in Embodiment 1 and therefore redundant will be omitted.
[0091] Referring to Figure 6, the sliding surface 311 of the stationary sealing ring 310 is provided with a plurality of spiral grooves 12, a plurality of forward rotation grooves 313, and a plurality of reverse rotation grooves 314.
[0092] The forward rotation groove 313 has a radial portion 316 and a forward circumferential portion 317. The reverse rotation groove 314 has a radial portion 316 and a reverse circumferential portion 318.
[0093] The circumferential portion 317 of the forward rotation groove 313 is inclined downstream and toward the inner diameter from the forward opening end 317a to the forward closing end 317b.
[0094] The positive closed end 317b of the circumferential portion 317 overlaps radially with the closed end 316b and the positive open end 317a of the adjacent downstream positive rotation groove 313. In other words, the positive closed end 317b overlaps radially with the circumferential portion 317 of the adjacent downstream positive rotation groove 313.
[0095] With this configuration, when the machine rotates in the reverse direction, the liquid F that flows out from the radial portion 316 or circumferential portion 317 of the forward rotation groove 313 on the reverse upstream side to the circumferential portion 317 of the forward rotation groove 313 on the reverse downstream side can be allowed to flow into the circumferential portion 317, thereby reducing leakage.
[0096] Furthermore, during forward rotation, the liquid F that flows out between the sliding surfaces 311 and 21 from the forward-closing end 317b and its vicinity in the upstream forward-rotation groove 313 is allowed to flow into the circumferential portion 317 of the downstream forward-rotation groove 313, making it easier to reduce leakage.
[0097] Furthermore, the inner diameter side surface of the circumferential portion 317 has a circumferentially extended surface 317d that extends along the circumferential direction and faces the positively closed end 317b, and an inclined surface 317e that extends from the reverse downstream end of the circumferentially extended surface 317d toward the outer diameter and reverse downstream. This inclined surface 317e makes it easier to guide the liquid F inside the circumferential portion 317 toward the outer diameter when it rotates in the reverse direction, thus making it easier to hinder its movement toward the inner space S1.
[0098] Furthermore, during forward rotation, the liquid F is more easily guided along the inclined surface 317e towards the inner diameter side, that is, towards the inner space S1 side where the pressure is lower than that of the outer space S2. This improves the efficiency of generating positive pressure at and near the positive closed end 317b at low speeds.
[0099] Furthermore, the outer diameter side surface of the circumferential portion 317 has a circumferentially extending surface 317f that extends along the circumferential direction, and an inclined surface 317g that extends inclined toward the inner diameter and downstream from the downstream end of the circumferentially extending surface 317f. The positive closed end 317b is defined by the circumferentially extending surface 317d and the inclined surface 317g, and since it is wider toward the reverse downstream side, it is easier to guide the liquid F inside the positive closed end 317b toward the reverse downstream side when rotating in reverse.
[0100] Furthermore, because the positive closure end 317b narrows towards the downstream side, it is easier to increase the dynamic pressure within the positive closure end 317b during positive rotation.
[0101] Furthermore, the positive closure end 317b overlaps in the circumferential direction with the region that the inclined surface 317e faces in the adjacent reverse upstream circumferential portion 317. This makes it easier for the liquid F that flows out from the reverse upstream circumferential portion 317 of the reverse upstream positive rotation groove 313 toward the reverse downstream side to flow into the reverse downstream positive rotation groove 317. [Examples]
[0102] Next, the sliding parts according to Embodiment 4 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.
[0103] Referring to Figure 7, the sliding surface 411 of the stationary sealing ring 410 is provided with a plurality of spiral grooves 12, a plurality of forward rotation grooves 413, and a plurality of reverse rotation grooves 14.
[0104] The forward rotation groove 413 has a radial portion 16 and a circumferential portion 417. The circumferential portion 417 is inclined downstream and toward the inner diameter from the positive opening end 417a to the positive closing end 417b. Furthermore, the circumferential portion 417 is arc-shaped and protrudes downstream and toward the outer diameter. Note that the circumferential portion may be linear or arc-shaped and protrudes downstream and toward the inner diameter.
[0105] Even with this configuration, when rotating in the reverse direction, the liquid F in the circumferential portion 417 is more easily guided along the circumferential portion 417 toward the outer diameter, thus making it easier to hinder its movement toward the inner space S1.
[0106] Furthermore, since the liquid F is more easily guided towards the inner space S1 side along the circumferential portion 417 during forward rotation, the efficiency of generating positive pressure at the positive closed end 417b and its vicinity at low speeds is improved. [Examples]
[0107] Next, the sliding parts according to Example 5 will be described with reference to Figure 8. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.
[0108] Referring to Figure 8, the sliding surface 511 of the stationary sealing ring 510 is provided with a plurality of spiral grooves 12, a plurality of forward rotation grooves 513, and a plurality of reverse rotation grooves 14.
[0109] The forward rotation groove 513 has a radial portion 16, a first inclined portion 517A which is part of the circumferential portion, and a second inclined portion 517B which is part of the circumferential portion.
[0110] The first inclined section 517A extends linearly, inclined downstream and toward the outer diameter from the inner diameter end 16b of the radial section 16. The upstream end of the first inclined section 517A is a positively open end 517Aa. The second inclined section 517B extends linearly, inclined downstream and toward the outer diameter from the downstream end 517Ab of the first inclined section 517A. The downstream end of the second inclined section 517B is a positively closed end 517Bb. Note that the first and second inclined sections may also be arc-shaped.
[0111] This configuration makes it easier for the liquid F that flows out from the positive closure end 517Bb and its vicinity during positive rotation to move downstream and toward the outer diameter. This suppresses movement toward the inner space S1 while facilitating the flow of liquid F into the adjacent downstream positive rotation groove 513.
[0112] Furthermore, since the second inclined portion 517B is provided along the extending direction of one spiral groove 12, the liquid F inside the second inclined portion 517B is easily blown out to the outside space S2 by the gas A that flows out from the spiral groove 12 between the sliding surfaces 11 and 21.
[0113] Furthermore, since the liquid F is more easily guided towards the internal space S1 side along the first inclined portion 517A during forward rotation, the efficiency of generating positive pressure at the positive closed end 517Bb and its vicinity at low speeds is improved.
[0114] Furthermore, the second inclined section 517B overlaps the first inclined section 517A, with which it is in communication, in the circumferential direction. This makes it easier to reduce leakage by allowing the liquid F that flows out from the second inclined section 517B toward the reverse downstream side during reverse rotation to flow into the first inclined section 517A.
[0115] Furthermore, the first inclined portion 517A is designed to easily guide the liquid F inside the first inclined portion 517A toward the outer diameter side along the first inclined portion 517A during reverse rotation, thus making it easier to hinder its movement toward the inner space S1 side.
[0116] Furthermore, the positive closed end 517Bb of the second inclined section 517B radially overlaps with the positive open end 517Aa of the adjacent reverse-upstream first inclined section 517A. This makes it easier to reduce leakage by allowing the liquid F that flows out from the radial section 516 of the reverse-upstream positive rotation groove 513 and the first inclined section 517A during reverse rotation to flow into the reverse-downstream positive rotation groove 513.
[0117] Furthermore, the second inclined section 517B overlaps circumferentially with the adjacent first inclined section 517A on the reverse upstream side. This makes it easier to reduce leakage by allowing the liquid F that flows out from the first inclined section 517A on the reverse upstream side to the sliding surfaces 511 and 21 during reverse rotation to flow into the second inclined section 517B on the reverse downstream side. [Examples]
[0118] Next, the sliding parts according to Embodiment 6 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.
[0119] Referring to Figure 9, the sliding surface 611 of the stationary sealing ring 610 is provided with a plurality of spiral grooves 12, a plurality of forward rotation grooves 613, and a plurality of reverse rotation grooves 14.
[0120] The forward rotation groove 613 has a radial portion 16, a first extension portion 617A as part of the circumferential portion, an inclined portion 617B as part of the circumferential portion, and a second extension portion 617C as part of the circumferential portion.
[0121] The first extension 617A extends circumferentially downstream from the inner diameter end 16b of the radial section 16. The inclined section 617B extends linearly, inclined downstream and towards the inner diameter from the downstream end 617Ab of the first extension 617A. The second extension 617C extends circumferentially downstream from the downstream end 617Bb of the inclined section 617B. The downstream end of the second extension 617C is the positive closed end 617Cb.
[0122] The second extension 617C overlaps radially with the first extension 617A in the adjacent downstream forward rotation groove 613. Furthermore, the forward closing end 617Cb overlaps radially and circumferentially with the inclined portion 617B in the adjacent downstream forward rotation groove 613.
[0123] This makes it easier to reduce leakage during reverse rotation by allowing the liquid F that has flowed out from the forward rotation groove 613 on the reverse upstream side to the sliding surfaces 611 and 21 to flow into the forward rotation groove 613 on the reverse downstream side.
[0124] Furthermore, during forward rotation, the liquid F that flows out from the upstream forward rotation groove 613 to the sliding surfaces 611 and 21 is allowed to flow into the downstream forward rotation groove 613, making it easier to reduce leakage.
[0125] Furthermore, because the liquid F is more easily guided towards the internal space S1 side along the inclined portion 617B during forward rotation, the efficiency of generating positive pressure at the positive closure end 617Cb and its vicinity at low speeds is improved.
[0126] Furthermore, each second extension section 617C is arranged on a concentric circle. This makes it easier for the liquid F that flows out from the upstream second extension section 617C during forward rotation to flow into the downstream second extension section 617C. Similarly, during reverse rotation, it makes it easier for the liquid F that flows out from the reverse upstream second extension section 617C to flow into the reverse downstream second extension section 617C.
[0127] As in this embodiment and in Embodiment 5, the shape of the circumferential portion may be modified as appropriate, as long as it has a positive closed end. The same applies to the reverse circumferential portion. [Examples]
[0128] Next, the sliding parts according to Embodiment 7 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.
[0129] Referring to Figure 10, the sliding surface 711 of the stationary sealing ring 710 is provided with a plurality of spiral grooves 12, a plurality of forward rotation grooves 713, and a plurality of reverse rotation grooves 714.
[0130] The forward rotation groove 713 is a groove of constant depth that extends inclined toward the inner diameter and downstream side from the forward opening end 713a, which communicates with the outer space S2. The depth of the forward rotation groove 713 is approximately the same as the depth of the circumferential portion 17 in Embodiment 1, but may be changed as appropriate.
[0131] The forward rotation groove 713 has an arc shape in which the upstream region 713c protrudes inward and upstream, and the downstream region 713d extends along the circumferential direction. The upstream region 713c has a positive open end 713a. The downstream region 713d has a positive closed end 713b. The positive closed end 713b overlaps radially with the positive open end 713a of the adjacent forward rotation groove 713 downstream.
[0132] The reverse rotation groove 714 extends circumferentially upstream from a reverse open end 714b that communicates with the radial center of the upstream region 713c. The upstream end of the reverse rotation groove 714 is the reverse closed end 714a.
[0133] Even with this configuration, positive pressure can be generated at the positive closing end 713b and its vicinity in the positive rotation groove 713 during positive rotation, thereby reducing the frictional force generated by the relative sliding of the sliding surfaces 711 and 21.
[0134] Furthermore, during forward rotation, the liquid F that flows out from the forward rotation groove 713 between the sliding surfaces 711 and 21 is allowed to flow into the adjacent downstream forward rotation groove 713 or reverse rotation groove 714, making it easier to reduce leakage.
[0135] Furthermore, during reverse rotation, positive pressure is generated at the reverse closed end 714a and its vicinity in the reverse rotation groove 714, thereby reducing the frictional force generated by the relative sliding of the sliding surfaces 711 and 21.
[0136] Furthermore, when rotating in reverse, the liquid F that flows out from the forward rotation groove 713 and the reverse rotation groove 714 is allowed to flow into the adjacent reverse-downstream forward rotation groove 713, making it easier to reduce leakage.
[0137] As described above, if the positive closure end overlaps radially with a portion of the forward rotation groove on the adjacent reverse upstream side, leakage of liquid F during reverse rotation can be reduced. In other words, the configuration of the forward rotation groove and the reverse rotation groove may be changed as appropriate, and may be a spiral groove, for example. [Examples]
[0138] Next, the sliding parts according to Example 8 will be described with reference to Figure 11. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.
[0139] Referring to Figure 11, the sliding surface 811 of the stationary sealing ring 810 is provided with a plurality of spiral grooves 812 (72 in this embodiment), 30 sets of forward rotation grooves 13, and 30 sets of reverse rotation grooves 14.
[0140] The multiple spiral grooves 812 have different lengths in the extension direction from the open end 812a to the closed end 812b. The multiple spiral grooves 812 are arranged so that each closed end 812b traces a sinusoidal contour. However, the contour traced by each closed end 812b may be a wave shape other than a sinusoid.
[0141] The multiple spiral grooves 812 are arranged such that, starting from the spiral groove 812L with the longest extension length, the radial length decreases as they move away from each other in the circumferential direction. Of the multiple spiral grooves 812, the spiral groove 812S with the shortest extension length is located in the center between two adjacent spiral grooves 812L in the circumferential direction.
[0142] As a result, the negative pressure generated in the spiral groove 812S and the nearby spiral groove 812 is less likely to affect the forward rotation groove 13 and the reverse rotation groove 14, thereby further reducing leakage of liquid F during reverse rotation.
[0143] Furthermore, the multiple dynamic pressure generating grooves are not limited to the multiple spiral grooves 812 in this embodiment, and may have only two lengths in the extending direction, as shown in the multiple spiral grooves as Modification 8-1 in Figure 12. In Figure 12, long spiral grooves 812L in sets of five and short spiral grooves 812S in sets of seven are alternately provided in the circumferential direction. Even with such a configuration, leakage of liquid F during reverse rotation can be further reduced.
[0144] On the other hand, from the viewpoint of easily increasing the positive pressure generated by the spiral grooves during forward rotation, the multiple spiral grooves 812 in this embodiment are preferable. [Examples]
[0145] Next, the sliding parts according to Example 9 will be described with reference to Figure 13. Note that descriptions of components that are identical to those in Example 1 and therefore redundant will be omitted.
[0146] Referring to Figure 13, in this embodiment, the inner space S91 is a sealed fluid space where liquid F is present, and the outer space S92 is a leak space where gas A is present.
[0147] The sliding surface 911 of the stationary sealing ring 910 is provided with 24 spiral grooves 912, 30 sets of forward rotation grooves 913, and 30 sets of reverse rotation grooves 914. In other words, the mechanical seal in this embodiment is of the outside type.
[0148] The spiral groove 912 communicates with the outer space S92 and extends inclined toward the downstream and inner diameter side.
[0149] The forward rotation groove 913 has a radial portion 916 that communicates with the internal space S91, and a circumferential portion 917 that extends downstream from the outer diameter end 916b of the radial portion 916. The downstream end of the circumferential portion 917 is a forward closed end 917b that overlaps radially and circumferentially with the adjacent downstream outer diameter end 916b.
[0150] The reverse rotation groove 914 has a radial portion 916 and a reverse circumferential portion 918 that extends upstream from the radial center of the radial portion 916.
[0151] As a result, during forward rotation, positive pressure is generated by the spiral groove 912 and the forward rotation groove 913, slightly separating the sliding surfaces 911 and 21 and reducing frictional force. In addition, the positive pressure generated by the spiral groove 912 can return the liquid F to the inner space S91.
[0152] During reverse rotation, the reverse rotation groove 914 generates positive pressure, slightly separating the sliding surfaces 911 and 21 and reducing friction. In addition, the forward rotation groove 913 prevents the liquid F that has flowed out from the reverse rotation groove 914 and the adjacent reverse-upstream forward rotation groove 913 between the sliding surfaces 911 and 21 from flowing out into the outer space S92.
[0153] In other words, the sliding component of the present invention can exhibit its effects even when applied to an outside-type mechanical seal.
[0154] 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.
[0155] For example, in the above embodiments 1 to 9, 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.
[0156] Furthermore, while Examples 1 to 9 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.
[0157] Furthermore, although one of the sliding surfaces was described as the sliding surface of a stationary sealing ring in Examples 1 to 9 above, it is not limited to this and may be the sliding surface of a rotating sealing ring.
[0158] Furthermore, while the above-described examples 1 to 9 illustrate configurations in which the number of grooves for forward rotation and the number of grooves for reverse rotation are equal, the system is not limited to this configuration and may have different configurations.
[0159] Furthermore, although the dynamic pressure generating groove was described as a spiral groove in Examples 1 to 9 above, 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.
[0160] 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.
[0161] Furthermore, although the spiral grooves in Examples 1 to 9 were described as being in communication with the leakage space, the design is not limited to this, and they 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.
[0162] Furthermore, although it was explained in Examples 1 to 9 that the spiral groove is provided on the leakage space side of the forward rotation groove, the invention is not limited to this, and the spiral groove may overlap the forward rotation groove in the circumferential direction.
[0163] 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.
[0164] 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 groove for forward rotation, that is, that the spiral groove and the groove for forward rotation do not overlap in the circumferential direction.
[0165] Furthermore, although the forward rotation groove was described in Examples 1 to 9 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.
[0166] Furthermore, although the reverse rotation groove was described in Examples 1 to 9 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.
[0167] Furthermore, while mechanical seals were used as examples of sliding parts in Examples 1 to 9, the invention is not limited to mechanical seals, and thrust bearings, radial bearings, plain bearings, etc., may also be used. [Explanation of Symbols]
[0168] 1. Axis of rotation 4 Housing 10 Stationary sealing ring 11. Sliding surface (one of the sliding surfaces) 12. Spiral groove (dynamic pressure generating groove) 13 Forward rotation groove 14 Reverse rotation groove 16 Radial section 17 Circumferential direction section 17b Positive closed end 18 Reverse circumferential section 18a Reverse closed end 20 Rotating Sealing Rings 21. Sliding surface (the other sliding surface) F Liquid (sealed fluid) S1 Internal space (leakage space) S2 Outside space (sealed fluid space)
Claims
1. A sliding component in which a pair of sliding surfaces are positioned at a location where they rotate relative to each other, thereby separating a leak space from a fluid space to be sealed, One of the sliding surfaces comprises a dynamic pressure generating groove located on the leakage space side and extending in the forward rotation direction of the relative rotation, a plurality of forward rotation grooves 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, The reverse closing end of the reverse rotation groove is provided on the side of the sealed fluid space that is closer than the forward rotation groove. The forward closing end of the forward rotation groove on the upstream side is a sliding component that radially overlaps at least a portion of the forward rotation groove on the downstream side on the leakage space side.
2. The forward rotation groove has a radial portion and a circumferential portion having the forward closed end, The sliding component according to claim 1, wherein the positive closing end of the upstream positive rotation groove overlaps radially with at least a portion of the radial portion of the downstream positive rotation groove.
3. The forward rotation groove has a radial portion and a circumferential portion having the forward closed end, The sliding component according to claim 1, wherein the positive closing end of the upstream positive rotation groove overlaps radially with at least a portion of the circumferential portion of the downstream positive rotation groove.
4. The sliding part according to claim 2 or 3, wherein at least a portion of the radial portion is inclined toward the circumferential portion.
5. The forward rotation groove and the reverse rotation groove share the radial portion, The sliding part according to claim 2 or 3, wherein the reverse rotation groove has a reverse circumferential portion having the reverse closed end.
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 some of the spiral grooves are shorter than the other spiral grooves.