Sliding component

Abstract

Provided is a sliding component capable of reliably introducing fluid into a dynamic pressure generating groove.　In this sliding component, sliding surfaces 11, 21 of a pair of sliding rings 10, 20 rotate relative to each other and define an outer diameter space S1 and an inner diameter space S2, and at least one of the sliding surfaces 11 includes: a dynamic pressure generating groove 12 extending in a circumferential direction; and a deep groove 14 which extends in a circumferential direction and in which a circumferential end 14a on a relative rotation downstream side communicates with a relative rotation upstream end 12b of one dynamic pressure generating groove 12.

Description

Sliding parts

[0001] The present invention relates to a sliding part, for example, a sliding part used in a shaft seal or a bearing.

[0002] In rotary machines, a mechanical seal consisting of a pair of annular sliding rings that rotate relative to each other and whose sliding surfaces slide against each other is known as a sliding component for preventing leakage of a sealed fluid around a rotating shaft. In recent years, there has been a demand for reducing the energy lost due to sliding, for example, in order to protect the environment, and some mechanical seals have dynamic pressure generating grooves on the sliding surfaces of the sliding rings.

[0003] For example, Patent Document 1 discloses a mechanical seal in which one sliding ring has a circumferential groove on its sliding surface, with a spiral groove formed on the inner diameter side of the circumferential groove. One end of the spiral groove is connected to the circumferential groove. During relative forward rotation of the pair of sliding rings, fluid stored in the circumferential groove can be introduced into the spiral groove to generate dynamic pressure at the closed end of the spiral groove. This causes a slight separation between the sliding surfaces, reducing the frictional force generated during relative sliding.

[0004] WO 2018 / 092742 (page 13, Figure 6)

[0005] In the mechanical seal of Patent Document 1, at the beginning of the relative forward rotation of the pair of sliding rings, i.e., during low-speed rotation, the fluid stored in the circumferential groove can be introduced into the spiral groove to reliably generate dynamic pressure. However, as the relative rotational speed of the pair of sliding rings increases, the fluid tends to flow circumferentially along the circumferential groove, which could make it difficult for the fluid to flow from the circumferential groove toward the spiral groove.

[0006] The present invention has been made in view of these problems, and has as its object to provide a sliding component that can reliably introduce fluid into dynamic pressure generating grooves.

[0007] In order to solve the above problems, the sliding component of the present invention is a sliding component in which sliding surfaces of a pair of sliding rings rotate relative to each other to partition an outer diameter space and an inner diameter space, at least one of the sliding surfaces comprising: a dynamic pressure generating groove extending in the circumferential direction; and a deep groove extending in the circumferential direction, the deep groove having a circumferential end portion on the downstream side in the relative rotation that communicates with an upstream end portion of one of the dynamic pressure generating grooves. With this, the circumferential end portion of the deep groove restricts the circumferential movement of the fluid and ensures that the fluid is introduced into the dynamic pressure generating groove, thereby making it possible to effectively generate dynamic pressure in the dynamic pressure generating groove.

[0008] The dynamic pressure generating groove may include an inner diameter side dynamic pressure generating groove and an outer diameter side dynamic pressure generating groove arranged radially outer than the inner diameter side dynamic pressure generating groove, and the deep groove may include an inner diameter side deep groove arranged radially outer than the inner diameter side dynamic pressure generating groove, having a circumferential end portion on the downstream side of relative rotation in the circumferential direction and communicating with the upstream end portion of the inner diameter side dynamic pressure generating groove, and an outer diameter side deep groove arranged radially inner than the outer diameter side dynamic pressure generating groove, having a circumferential end portion on the downstream side of relative rotation in the circumferential direction and communicating with the upstream end portion of the outer diameter side dynamic pressure generating groove.In this configuration, fluid is introduced from the inner diameter side deep groove to the inner diameter side dynamic pressure generating groove and then introduced into the outer diameter side dynamic pressure generating groove, so that fluid is less likely to leak between the sliding surfaces from the inner diameter side deep groove and the outer diameter side deep groove, and the fluids are less likely to mix.

[0009] The circumferential end of the deep groove may be directly connected to the side wall of the upstream end of the hydrodynamic groove in the relative rotation direction, thereby enabling fluid to be smoothly and reliably supplied from the deep groove to the hydrodynamic groove.

[0010] At least one of the downstream end of the inner diameter side dynamic pressure generating groove for relative rotation and the downstream end of the outer diameter side dynamic pressure generating groove for relative rotation may be tapered inward or outward in the axial direction, whereby fluid is discharged from the inner diameter side dynamic pressure generating groove to the inner diameter side and from the outer diameter side dynamic pressure generating groove to the outer diameter side, thereby preventing the dynamic pressures generated in the inner diameter side dynamic pressure generating groove and the outer diameter side dynamic pressure generating groove from interfering with each other.

[0011] A pressure release groove extending in the circumferential direction may be provided between the inner diameter deep groove and the outer diameter deep groove. With this, the fluids are recovered by the recovery groove, making it difficult for the fluids to mix and suppressing interference between the dynamic pressures generated in the inner diameter dynamic pressure generating groove and the outer diameter dynamic pressure generating groove.

[0012] A reservoir groove may be provided on the circumferential extension of the deep groove, so that the fluids are collected by the reservoir groove and are less likely to mix with each other.

[0013] The downstream end of the dynamic pressure generating groove in the relative rotation may be disposed between the deep grooves adjacent in the circumferential direction, whereby the downstream end of the dynamic pressure generating groove in the relative rotation is disposed circumferentially offset from the adjacent downstream deep groove, thereby improving the dynamic pressure effect generated at the downstream end of the relative rotation.

[0014] The bearing may further include a reverse dynamic pressure generating groove extending circumferentially opposite to the dynamic pressure generating groove, and the deep groove may have a circumferential end communicating with an upstream end of the reverse dynamic pressure generating groove in the relative rotation direction. With this, dynamic pressure is generated in the dynamic pressure generating groove during forward rotation, allowing the fluid to be recovered by the reverse dynamic pressure generating groove, and dynamic pressure is generated in the reverse dynamic pressure generating groove during reverse rotation, allowing the fluid to be recovered by the dynamic pressure generating groove.

[0015] A dynamic pressure generating element may be provided in communication with the outer diameter space or the inner diameter space, which can increase the floating effect between the sliding surfaces and improve lubrication.

[0016] Fig. 2 is a longitudinal sectional view showing an example of a mechanical seal in a first embodiment of the present invention. Fig. 3 is a view of the sliding surface of the stationary seal ring in the first embodiment as viewed from the axial direction. Fig. 4 is an enlarged view of a main part of Fig. 2. Fig. 4 is a view of the sliding surface of the stationary seal ring when the rotating seal ring rotates forward as viewed from the axial direction. Fig. 5 is a view of the sliding surface of the stationary seal ring when the rotating seal ring rotates backward as viewed from the axial direction. Fig. 5 is a view of the sliding surface of the stationary seal ring in a second embodiment of the present invention as viewed from the axial direction. Fig. 6 is a view of the sliding surface of the stationary seal ring in a third embodiment of the present invention as viewed from the axial direction. Fig. 7 is a view showing a modified example of the sliding surface of the stationary seal ring in the first embodiment of the present invention.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sliding element according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0018] A sliding component according to a first embodiment will be described with reference to Figures 1 to 5. In this embodiment, a mechanical seal will be used as an example of the sliding component. In the mechanical seal of this embodiment, a first fluid F1, such as oil, exists in an outer space S1, which is an outer diameter space, and a second fluid F2, such as water, exists in an inner space S2, which is an inner diameter space. For ease of explanation, grooves formed on the sliding surface may be indicated by dots in the drawings.

[0019] 1 is an inside type mechanical seal that seals against a first fluid F1 that attempts to leak from the outer diameter side to the inner diameter side of the sliding surface. That is, an example will be described in which the first fluid F1 is at a higher pressure than the second fluid F2.

[0020] The mechanical seal is mainly composed of a stationary seal ring 10 and a rotary seal ring 20. The stationary seal ring 10 is annular and is mounted on a seal cover 5 fixed to a housing 4 of the device to which it is attached in a non-rotating state but movable in the axial direction. The rotary seal ring 20 is annular and is mounted on a rotary shaft 1 via a sleeve 2 so as to be rotatable together with the rotary shaft 1. The stationary seal ring 10 is axially biased by an elastic member 7. The sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotary seal ring 20 slide closely against each other. The sliding surface 21 of the rotary seal ring 20 is flat and does not have any recesses such as grooves.

[0021] The stationary seal ring 10 and the rotating seal ring 20 are typically formed from a combination of SiC (hard material) or SiC (hard material) and carbon (soft material), but any sliding material used as a sliding material for mechanical seals can be used. Examples of SiC include sintered bodies using boron, aluminum, carbon, or other sintering aids, as well as materials consisting of two or more phases with different components and compositions, such as SiC with dispersed graphite particles, reaction-sintered SiC consisting of SiC and Si, SiC-TiC, and SiC-TiN. Examples of carbon include a mixture of carbonaceous and graphitic materials, resin-molded carbon, and sintered carbon. In addition to the above sliding materials, metal materials, resin materials, surface-modified materials (coating materials), composite materials, and the like can also be used.

[0022] 2, the rotary seal ring 20 slides relative to the stationary seal ring 10 in a counterclockwise direction as indicated by the solid arrow and in a clockwise direction as indicated by the dashed arrow. In the following description, the direction of the solid arrow indicates the forward rotation direction of the rotary seal ring 20, and the direction of the dashed arrow indicates the reverse rotation direction of the rotary seal ring 20.

[0023] The sliding surface 11 of the stationary seal ring 10 is provided with a dynamic pressure generating mechanism A, a dynamic pressure generating mechanism B, an annular groove 18, and a dynamic pressure generating element 19, and the remaining flat surface portion forms a land portion L.

[0024] A plurality of dynamic pressure generating mechanisms A and B (four of each in this embodiment) are equally spaced in the circumferential direction.

[0025] The dynamic pressure generating mechanism A is composed of an outer diameter side dynamic pressure generating groove 12, an outer diameter side reverse dynamic pressure generating groove 13, and an outer diameter side deep groove 14.

[0026] The dynamic pressure generating mechanism B is composed of an inner diameter side dynamic pressure generating groove 15 , an inner diameter side reverse dynamic pressure generating groove 16 , and an inner diameter side deep groove 17 .

[0027] The annular groove 18 is composed of an annular portion 18a provided on the outer diameter side of the dynamic pressure generating mechanism A and communication portions 18b that communicate with the external space S1 at multiple locations (four locations in this embodiment) in the circumferential direction of the annular portion 18a. The communication portions 18b are arranged circumferentially offset from the outer diameter side deep groove 14 and the inner diameter side deep groove 17.

[0028] A plurality of dynamic pressure generating elements 19 (four in this embodiment) are formed in the region surrounded by the annular portion 18 a and the two adjacent communicating portions 18 b. The dynamic pressure generating elements 19 are arranged at positions overlapping the outer diameter side deep groove 14 and the inner diameter side deep groove 17 in the radial direction.

[0029] The dynamic pressure generating element 19 includes a radial groove 19 a communicating with the outer space S1, and Rayleigh steps 19 b, 19 c extending from the inner diameter end of the radial groove 19 a to both sides in the circumferential direction. The radial groove 19 a is formed to the same depth as the Rayleigh steps 19 b, 19 c, but may be formed to a different depth.

[0030] First, the dynamic pressure generating mechanism A will be described in detail. As shown in Figure 3, the outer diameter side deep groove 14 is generally arc-shaped and extends generally concentrically with the sliding surface 11. The outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13 are disposed on the outer diameter side of the outer diameter side deep groove 14. The outer diameter side deep groove 14, the outer diameter side dynamic pressure generating groove 12, and the outer diameter side reverse dynamic pressure generating groove 13 are surrounded by a land portion L and are isolated from the outer space S1 and the inner space S2.

[0031] Specifically, the outer diameter side dynamic pressure generating groove 12 has a circumferential portion 12 a, an inclined portion 12 b, and an end portion 12 c. The circumferential portion 12 a is disposed on the outer diameter side of the outer diameter side deep groove 14 and extends substantially concentrically with the sliding surface 11.

[0032] The end 12c is one end of the circumferential portion 12a, i.e., the end portion on the downstream side in the relative rotation direction during forward rotation, and tapers from the circumferential portion 12a toward the outer diameter as viewed in the axial direction. The end 12c is located on the inner diameter side of the communicating portion 18b of the annular groove 18.

[0033] The inclined portion 12b is the other end of the circumferential portion 12a, that is, the upstream end in the direction of relative rotation during forward rotation, and extends radially inward from the circumferential portion 12a while inclining upstream in the direction of relative rotation.

[0034] The inclined portion 12b is connected to the outer diameter side of the outer diameter side deep groove 14. In other words, the inclined portion 12b of the outer diameter side dynamic pressure generating groove 12 is superimposed on, i.e., overlaps in the radial direction with, the outer diameter side deep groove 14. An inner diameter side wall 12d of the inclined portion 12b is connected to a circumferential end portion 14a on one end side of the outer diameter side deep groove 14.

[0035] The outer diameter side reverse dynamic pressure generating groove 13 has a circumferential portion 13 a, an inclined portion 13 b, and an end portion 13 c. The circumferential portion 13 a is disposed on the outer diameter side of the outer diameter side deep groove 14 and extends substantially concentrically with the sliding surface 11.

[0036] The end 13c is the other end of the circumferential portion 13a, i.e., the upstream end in the direction of relative rotation during forward rotation, and tapers radially outward from the circumferential portion 13a as viewed in the axial direction. The end 13c is located radially inward relative to the communicating portion 18b of the annular groove 18.

[0037] The inclined portion 13b is one end of the circumferential portion 13a, that is, the downstream end in the relative rotation direction during forward rotation, and extends radially inward from the circumferential portion 13a while inclining downstream in the relative rotation direction.

[0038] The inclined portion 13b is connected to the outer diameter side of the outer diameter side deep groove 14. In other words, the inclined portion 13b of the outer diameter side reverse dynamic pressure generating groove 13 is radially superimposed on, i.e., overlaps with, the outer diameter side deep groove 14. An inner diameter side wall 13d of the inclined portion 13b is connected to the circumferential end 14b on the other end side of the outer diameter side deep groove 14.

[0039] The inclined portion 12b of the outer diameter side dynamic pressure generating groove 12 and the inclined portion 13b of the outer diameter side reverse dynamic pressure generating groove 13 are in communication with each other in the circumferential direction.

[0040] The outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13 are formed to the same depth, and are formed to be shallower than the outer diameter side deep groove 14 .

[0041] The dynamic pressure generating mechanism A has a symmetrical shape with respect to an imaginary line α that passes through the circumferential center of the outer diameter side deep groove 14 and extends in the radial direction.

[0042] Next, the dynamic pressure generating mechanism B will be described. The inner diameter side deep groove 17 is substantially arc-shaped and extends substantially concentrically with the sliding surface 11. The inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 are disposed on the inner diameter side of the inner diameter side deep groove 17. In other words, the inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 do not overlap with the outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13 in the circumferential direction. The inner diameter side deep groove 17, the inner diameter side dynamic pressure generating groove 15, and the inner diameter side reverse dynamic pressure generating groove 16 are surrounded by the land portion L and are isolated from the outer space S1 and the inner space S2.

[0043] Specifically, the inner diameter side dynamic pressure generating groove 15 has a circumferential portion 15 a, an inclined portion 15 b, and an end portion 15 c. The circumferential portion 15 a is disposed on the inner diameter side of the inner diameter side deep groove 17 and extends substantially concentrically with the sliding surface 11.

[0044] The end 15c is one end of the circumferential portion 15a, i.e., the downstream end in the direction of relative rotation during forward rotation, and tapers radially inward from the circumferential portion 15a as viewed in the axial direction. The end 15c radially overlaps the communicating portion 18b of the annular groove 18.

[0045] The inclined portion 15b is the other end of the circumferential portion 15a, that is, the upstream end in the direction of relative rotation during forward rotation, and extends radially outward from the circumferential portion 15a while inclining toward the upstream side in the direction of relative rotation.

[0046] The inclined portion 15b is connected to the inner diameter side of the inner diameter deep groove 17. In other words, the inclined portion 15b of the inner diameter side dynamic pressure generating groove 15 is superimposed on, i.e., overlaps in the radial direction with, the inner diameter side deep groove 17. An outer diameter side wall 15d of the inclined portion 15b is connected to a circumferential end portion 17a on one end side of the inner diameter side deep groove 17.

[0047] The inner diameter side reverse dynamic pressure generating groove 16 has a circumferential portion 16 a, an inclined portion 16 b, and an end portion 16 c. The circumferential portion 16 a is disposed on the inner diameter side of the inner diameter side deep groove 17 and extends substantially concentrically with the sliding surface 11.

[0048] The end 16c is the other end of the circumferential portion 16a, i.e., the upstream end in the direction of relative rotation during forward rotation, and tapers radially inward from the circumferential portion 16a as viewed in the axial direction. The end 16c radially overlaps the communicating portion 18b of the annular groove 18.

[0049] The inclined portion 16b is one end of the circumferential portion 16a, that is, the downstream end in the relative rotation direction during forward rotation, and extends radially outward from the circumferential portion 16a while inclining downstream in the relative rotation direction.

[0050] The inclined portion 16b is connected to the inner diameter side of the inner diameter deep groove 17. In other words, the inclined portion 16b of the inner diameter side reverse dynamic pressure generating groove 16 is superimposed on, i.e., overlaps in the radial direction with, the inner diameter side deep groove 17. An outer diameter side wall 16d of the inclined portion 16b is connected to a circumferential end portion 17b on the other end side of the inner diameter side deep groove 17.

[0051] The inclined portion 15b of the inner diameter side dynamic pressure generating groove 15 and the inclined portion 16b of the inner diameter side reverse dynamic pressure generating groove 16 are in communication with each other in the circumferential direction.

[0052] The inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 are formed to the same depth, and are formed to be shallower than the outer diameter side deep groove 14 .

[0053] The dynamic pressure generating mechanism B has a symmetrical shape with respect to an imaginary line α that passes through the circumferential center of the inner diameter side deep groove 17 and extends in the radial direction.

[0054] Next, the flow of the first fluid F1 and the second fluid F2 during relative rotation between the stationary seal ring 10 and the rotary seal ring 20 will be explained with reference to Figures 4 and 5. Note that the relative rotational speed between the stationary seal ring 10 and the rotary seal ring 20 will not be specified here.

[0055] First, when the rotating seal ring 20 is stopped and not rotating, the first fluid F1 flows into the dynamic pressure generating mechanism A, the annular groove 18, and the dynamic pressure generating element 19, which are close to the outer space S1, and the second fluid F2 flows into the dynamic pressure generating mechanism B, which is close to the inner space S2.

[0056] The sliding surfaces 11 and 21 are in contact with each other, and the first fluid F1 and the second fluid F2 are hardly mixed between the sliding surfaces 11 and 21.

[0057] Next, a state in which the rotary seal ring 20 rotates relative to the stationary seal ring 10 in the forward direction will be described.

[0058] As shown in FIG. 4, when the rotary seal ring 20 rotates relative to the stationary seal ring 10 in the forward direction, the first fluid F1 and the second fluid F2 move within the grooves in the direction of rotation of the stationary seal ring 10.

[0059] Specifically, in the dynamic pressure generating element 19, the first fluid F1 moves to the closed end 19d of the Rayleigh step 19b, generating positive pressure at and near the closed end 19d. The force of the positive pressure generated at and near the closed end 19d of the Rayleigh step 19b separates the sliding surfaces 11, 21 from each other, improving lubricity and suppressing wear between the sliding surfaces 11, 21.

[0060] In the Rayleigh step 19c on the opposite side, the first fluid F1 moves from the closed end 19e to the radial groove 19a, generating a relative negative pressure at the closed end 19e and its vicinity. Therefore, the relative negative pressure generated at the closed end 19e of the Rayleigh step 19c and its vicinity sucks in the surrounding first fluid F1. Note that the relative negative pressure here does not refer to a vacuum state, but rather to a state where the pressure is lower than the ambient pressure.

[0061] The first fluid F1 that flows out from the closed end 19d of the Rayleigh step 19b to between the sliding surfaces 11 and 21 is collected by the annular groove 18 and returned to the outer space S1.

[0062] In the dynamic pressure generating mechanism A, a positive pressure is generated at the end 12c of the outer diameter side dynamic pressure generating groove 12 and in its vicinity, and a relative negative pressure is generated at the end 13c of the outer diameter side reverse dynamic pressure generating groove 13 and in its vicinity.

[0063] More specifically, the first fluid F1 is supplied to the outer diameter side dynamic pressure generating groove 12 through the outer diameter side deep groove 14 and the communicating portion with the outer diameter side reverse dynamic pressure generating groove 13. The movement of the first fluid F1 flowing through the outer diameter side deep groove 14 downstream in the relative rotation is restricted by the circumferential end portion 14a on the downstream side of the relative rotation of the outer diameter side deep groove 14, and the first fluid F1 is guided toward the inclined portion 12b of the outer diameter side dynamic pressure generating groove 12 that is in communication in the radial direction. This ensures that the first fluid F1 is introduced into the outer diameter side dynamic pressure generating groove 12, thereby effectively generating dynamic pressure at and near the end portion 12c of the outer diameter side dynamic pressure generating groove 12.

[0064] Furthermore, since a large amount of the first fluid F1 is stored in the outer diameter deep groove 14, a sufficient amount of the first fluid F1 can be supplied to the outer diameter dynamic pressure generating groove 12 from low relative rotation speeds to high relative rotation speeds, thereby preventing poor lubrication.

[0065] Furthermore, since a relative negative pressure is generated at and near the end 13 c of the outer diameter side reverse dynamic pressure generating groove 13, the first fluid F1 can be recovered from and near the end 13 c. The recovered first fluid F1 is supplied to the outer diameter side deep groove 14 or the outer diameter side dynamic pressure generating groove 12.

[0066] In the dynamic pressure generating mechanism B, a positive pressure is generated at the end 15c of the inner diameter side dynamic pressure generating groove 15 and in its vicinity, and a relative negative pressure is generated at the end 16c of the inner diameter side reverse dynamic pressure generating groove 16 and in its vicinity.

[0067] More specifically, the second fluid F2 is supplied to the inner diameter side dynamic pressure generating groove 15 through the inner diameter side deep groove 17 and the communicating portion with the inner diameter side reverse dynamic pressure generating groove 16. The second fluid F2 flowing through the inner diameter side deep groove 17 is restricted from moving downstream in the relative rotation direction by the circumferential end portion 17a on the downstream side of the relative rotation of the inner diameter side deep groove 17, and is guided toward the inclined portion 15b of the inner diameter side dynamic pressure generating groove 15 that communicates in the radial direction. This ensures that the second fluid F2 is introduced into the inner diameter side dynamic pressure generating groove 15, making it possible to effectively generate dynamic pressure at and near the end portion 15c of the inner diameter side dynamic pressure generating groove 15.

[0068] Furthermore, since a large amount of the second fluid F2 is stored in the inner diameter deep groove 17, a sufficient amount of the second fluid F2 can be supplied to the inner diameter dynamic pressure generating groove 15 from low relative rotation speeds to high relative rotation speeds, thereby preventing poor lubrication.

[0069] Furthermore, since a relative negative pressure is generated at and near the end 16 c of the inner diameter side reverse dynamic pressure generating groove 16, the second fluid F2 can be recovered at and near the end 16 c. The recovered second fluid F2 is supplied to the inner diameter side deep groove 17 or the inner diameter side dynamic pressure generating groove 15.

[0070] Next, a state in which the rotary seal ring 20 rotates relative to the stationary seal ring 10 in the reverse direction will be described.

[0071] As shown in Figure 5, when the rotating seal ring 20 rotates in the opposite direction relative to the stationary seal ring 10, the first fluid F1 and the second fluid F2 move within each groove in the direction of rotation of the stationary seal ring 10.

[0072] Specifically, in the dynamic pressure generating element 19, a positive pressure is generated at and near the closed end 19e of the Rayleigh step 19c, and a relative negative pressure is generated at and near the closed end 19d of the opposite Rayleigh step 19b.

[0073] The positive pressure generated at and near the closed end 19e separates the sliding surfaces 11, 21, improving lubrication and suppressing wear between the sliding surfaces 11, 21. Furthermore, the relative negative pressure generated at and near the closed end 19d sucks in the first fluid F1 around it.

[0074] The first fluid F1 that flows out between the sliding surfaces 11 and 21 from the closed end 19d of the Rayleigh step 19b and its vicinity is recovered by the annular groove 18 and returned to the outer space S1.

[0075] In the dynamic pressure generating mechanism A, a positive pressure is generated at the end 13c of the outer diameter side reverse dynamic pressure generating groove 13 and in its vicinity, and a relative negative pressure is generated at the end 12c of the outer diameter side dynamic pressure generating groove 12 and in its vicinity.

[0076] The first fluid F1 flowing through the outer diameter side deep groove 14 is restricted from moving downstream in the relative rotation direction by the circumferential end portion 14b of the outer diameter side deep groove 14 on the downstream side in the relative rotation direction, and is guided toward the inclined portion 13b of the radially communicating outer diameter side reverse dynamic pressure generation groove 13. This ensures that the first fluid F1 is introduced into the outer diameter side reverse dynamic pressure generation groove 13, thereby effectively generating dynamic pressure at and near the end portion 13c of the outer diameter side reverse dynamic pressure generation groove 13.

[0077] Furthermore, since a large amount of the first fluid F1 is stored in the outer diameter deep groove 14, a sufficient amount of the first fluid F1 can be supplied to the outer diameter reverse dynamic pressure generating groove 13 from low relative rotation speeds to high relative rotation speeds, thereby preventing poor lubrication.

[0078] Furthermore, since a relative negative pressure is generated at and near the end 12 c of the outer diameter side dynamic pressure generating groove 12, the first fluid F1 can be recovered from and near the end 12 c. The recovered first fluid F1 is supplied to the outer diameter side deep groove 14 or the outer diameter side reverse dynamic pressure generating groove 13.

[0079] In the dynamic pressure generating mechanism B, a positive pressure is generated at the end 16c of the inner diameter side reverse dynamic pressure generating groove 16 and in its vicinity, and a relative negative pressure is generated at the end 15c of the inner diameter side dynamic pressure generating groove 15 and in its vicinity.

[0080] The second fluid F2 flowing through the inner diameter deep groove 17 is restricted from moving downstream in the relative rotation direction by the circumferential end portion 17b of the inner diameter deep groove 17 on the downstream side in the relative rotation direction, and is guided toward the inclined portion 16b of the inner diameter side reverse dynamic pressure generation groove 16, which is in communication in the radial direction. This ensures that the second fluid F2 is introduced into the inner diameter side reverse dynamic pressure generation groove 16, and therefore dynamic pressure can be effectively generated at and near the end portion 16c of the inner diameter side reverse dynamic pressure generation groove 16.

[0081] Furthermore, since a large amount of the second fluid F2 is stored in the inner diameter deep groove 17, a sufficient amount of the second fluid F2 can be supplied to the inner diameter reverse dynamic pressure generating groove 16 from low relative rotation speeds to high relative rotation speeds, thereby preventing poor lubrication.

[0082] Furthermore, since a relative negative pressure is generated at and near the end 15 c of the inner diameter side dynamic pressure generating groove 15, the second fluid F2 can be recovered at and near the end 15 c. The recovered second fluid F2 is supplied to the inner diameter side deep groove 17 or the inner diameter side reverse dynamic pressure generating groove 16.

[0083] As described above, during forward rotation, the movement of the first fluid F1 downstream in the relative rotation direction is restricted by the circumferential end 14a of the outer diameter side deep groove 14. This ensures that the first fluid F1 is introduced into the outer diameter side dynamic pressure generating groove 12, which has the inner diameter side wall 12d continuous with the circumferential end 14a of the outer diameter side deep groove 14, and therefore dynamic pressure can be effectively generated at the end 12c of the outer diameter side dynamic pressure generating groove 12.

[0084] The sliding surface 11 also includes an outer diameter side dynamic pressure generating mechanism A and an inner diameter side dynamic pressure generating mechanism B. With this, the first fluid F1 is introduced from the outer diameter side deep groove 14 to the outer diameter side dynamic pressure generating groove 12, and the second fluid F2 is introduced from the inner diameter side deep groove 17 to the inner diameter side dynamic pressure generating groove 15, so that the first fluid F1 and the second fluid F2 are less likely to leak from the outer diameter side deep groove 14 and the inner diameter side deep groove 17 between the sliding surfaces 11, 21, and the fluids are less likely to mix.

[0085] Furthermore, the outer diameter side dynamic pressure generating groove 12 is disposed on the outer diameter side of the outer diameter side deep groove 14, and the inner diameter side dynamic pressure generating groove 15 is disposed on the inner diameter side of the inner diameter side deep groove 17. The fluid that flows out between the sliding surfaces 11, 21 from the outer diameter side dynamic pressure generating groove 12 is collected in the outer diameter side deep groove 14, and the fluid that flows out between the sliding surfaces 11, 21 from the inner diameter side dynamic pressure generating groove 15 is collected in the inner diameter side deep groove 17, so the fluids do not easily mix together.

[0086] Furthermore, since the outer diameter side deep groove 14 and the inner diameter side deep groove 17 can be brought closer to each other in the radial direction, the lubrication can be improved over a wide range in the radial direction.

[0087] Furthermore, the end 12c of the outer diameter side dynamic pressure generating groove 12 tapers outward in the axial direction, while the end 15c of the inner diameter side dynamic pressure generating groove 15 tapers inward in the axial direction. This allows the fluids to be discharged in directions away from the end 12c of the outer diameter side dynamic pressure generating groove 12 and the end 15c of the inner diameter side dynamic pressure generating groove 15 in the radial direction, making it difficult for the fluids to mix, and preventing the dynamic pressures generated in the outer diameter side dynamic pressure generating groove 12 and the inner diameter side dynamic pressure generating groove 15 from interfering with each other.

[0088] Furthermore, one outer diameter side dynamic pressure generating groove 12 communicates with one outer diameter side deep groove 14, and one inner diameter side dynamic pressure generating groove 15 communicates with one inner diameter side deep groove 17. In this configuration, the fluid is introduced concentratedly into the outer diameter side dynamic pressure generating groove 12 and the inner diameter side dynamic pressure generating groove 15, compared to a configuration in which multiple dynamic pressure generating grooves communicate with one deep groove, so the dynamic pressure effect is high.

[0089] Furthermore, the end 12c of the outer diameter side dynamic pressure generating groove 12 and the end 15c of the inner diameter side dynamic pressure generating groove 15 are arranged circumferentially offset from the outer diameter side deep groove 14 and the inner diameter side deep groove 17, and since no grooves are formed around the ends 12c and 15c, the dynamic pressure effect generated at the ends 12c and 15c can be improved.

[0090] Furthermore, it has outer diameter side reverse dynamic pressure generating grooves 13 extending circumferentially opposite to the outer diameter side dynamic pressure generating grooves 12, and during reverse rotation, the first fluid F1 is guided into the outer diameter side reverse dynamic pressure generating grooves 13 by the circumferential ends 14b of the outer diameter side deep grooves 14. During forward rotation, dynamic pressure is generated in the outer diameter side dynamic pressure generating grooves 12, and the first fluid F1 can be recovered by the outer diameter side reverse dynamic pressure generating grooves 13, and during reverse rotation, dynamic pressure is generated in the outer diameter side reverse dynamic pressure generating grooves 13, and the first fluid F1 can be recovered by the outer diameter side dynamic pressure generating grooves 12.

[0091] Furthermore, since the dynamic pressure generating element 19 is provided in communication with the external space S1, the floating effect between the sliding surfaces 11 and 21 can be enhanced, thereby improving lubrication.

[0092] Furthermore, the inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 do not overlap in the circumferential direction with the outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13. In other words, the inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 are spaced apart in the radial direction from the outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13, respectively, and therefore the fluids do not easily mix with each other.

[0093] In this embodiment, the example shows an embodiment in which the inner diameter sidewall of the inclined portion 12b is continuous with the circumferential end 14a of the outer diameter deep groove 14 and the outer diameter sidewall of the inclined portion 15b is continuous with the circumferential end 17a of the inner diameter deep groove 17, but the circumferential end of the deep groove may be located downstream or upstream of the upstream end of the dynamic pressure generating groove in the relative rotation direction. Even in this case, the circumferential movement of the fluid is restricted by the circumferential end of the deep groove, thereby ensuring that the fluid is introduced into the dynamic pressure generating groove.

[0094] Furthermore, the outer diameter side deep groove 14 and the inner diameter side deep groove 17 are not limited to being arc-shaped, but may extend in other curved shapes such as straight lines or wave shapes.

[0095] Furthermore, the outer diameter side deep groove and the inner diameter side deep groove may be formed to be longer in the circumferential direction than in the embodiment, but it is preferable that the outer diameter side deep groove and the inner diameter side deep groove are shorter than the outer diameter side dynamic pressure generating groove and the inner diameter side dynamic pressure generating groove so that they do not overlap radially with the respective downstream ends of the outer diameter side dynamic pressure generating groove and the inner diameter side dynamic pressure generating groove relative to rotation.

[0096] Next, a sliding element according to a second embodiment will be described with reference to Fig. 6. Note that the description of the same configuration as in the first embodiment will be omitted.

[0097] 6 , a plurality of recovery grooves 30 serving as pressure release grooves are provided in the circumferential direction on the sliding surface 211 of the stationary seal ring 210 of the second embodiment between the dynamic pressure generating mechanisms A and B which are spaced apart in the radial direction. The recovery grooves 30 are generally arc-shaped and extend in the circumferential direction, and are deeper than the dynamic pressure generating grooves of the external dynamic pressure generating mechanisms A and B. These recovery grooves 30 are spaced apart in the circumferential direction and are arranged over substantially the entire circumference of the sliding surface 211.

[0098] Furthermore, a plurality of arc-shaped grooves 40 as inner diameter side storage grooves and a plurality of arc-shaped grooves 50 as outer diameter side storage grooves are arranged circumferentially spaced apart on substantially concentric circles of the outer diameter side deep groove 14 and the inner diameter side deep groove 17. The arc-shaped grooves 40, 50 have substantially the same shape as the recovery groove 30. Furthermore, the arc-shaped grooves 40, 50 are arranged circumferentially offset from the recovery groove 30.

[0099] The arc-shaped grooves 40, 50 are not provided around the ends 12c, 13c of the dynamic pressure generating mechanism A and the ends 15c, 16c of the dynamic pressure generating mechanism B.

[0100] With this, the fluids are recovered by the recovery groove 30 and the arc-shaped grooves 40, 50, so that the fluids are less likely to mix and the dynamic pressures generated by the dynamic pressure generating mechanisms A, B can be prevented from interfering with each other.

[0101] Furthermore, since the arcuate grooves 40, 50 are not provided around the ends 12c, 13c of the dynamic pressure generating mechanism A and the ends 15c, 16c of the dynamic pressure generating mechanism B, the arcuate grooves 40, 50 do not affect the dynamic pressure effect.

[0102] In the second embodiment, the recovery groove 30 is disposed in the sliding surface 211 in a ring shape as shown by a broken line when viewed in the axial direction, but may be formed in a ring shape connected in the circumferential direction.

[0103] Furthermore, the arc-shaped grooves 40 and 50 are not essential components, and these components may be omitted.

[0104] The arc-shaped grooves 40, 50 may also be configured to be arranged in a broken-line annular shape as viewed in the axial direction.

[0105] Next, a sliding element according to a third embodiment will be described with reference to Fig. 7. Note that the description of the same configuration as in the second embodiment will be omitted.

[0106] 7 , the arc-shaped grooves 40′ of the third embodiment are provided two on each side of the outer diameter deep groove 14 in the circumferential direction, spaced apart from each other. The arc-shaped grooves 40′, 40′ on the circumferentially farther side from the outer diameter deep groove 14 are positioned closer to the outer diameter deep groove 14 than an imaginary line β extending in the radial direction and passing through midpoints between the ends 14a, 14b of the outer diameter deep groove 14 and the ends 12c, 13c of the dynamic pressure generating mechanism A.

[0107] In the third embodiment, two arc-shaped grooves 50' are provided circumferentially spaced apart on each side of the inner diameter deep groove 17. The arc-shaped grooves 50', 50' circumferentially farther from the inner diameter deep groove 17 are positioned closer to the inner diameter deep groove 17 than the imaginary line β.

[0108] This allows sufficient land areas to be formed around the ends 12c, 13c of the dynamic pressure generating mechanism A and the ends 15c, 16c of the dynamic pressure generating mechanism B, thereby further enhancing the dynamic pressure effect compared to the second embodiment.

[0109] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0110] For example, in the first to third embodiments, an outer diameter side dynamic pressure generating mechanism A and an inner diameter side dynamic pressure generating mechanism B are provided, but it is sufficient if only one type of dynamic pressure generating mechanism is provided.

[0111] Furthermore, in the above-described Examples 1 to 3, a configuration was exemplified in which multiple dynamic pressure generating mechanisms A on the outer diameter side and multiple dynamic pressure generating mechanisms B on the inner diameter side were provided in the circumferential direction, but it is sufficient that at least one dynamic pressure generating mechanism is provided in the circumferential direction, rather than multiple mechanisms.

[0112] Furthermore, the dynamic pressure generating mechanism A and the inner diameter side dynamic pressure generating mechanism B do not necessarily have to be arranged so as to overlap in the radial direction, but may be arranged so as to be shifted in the circumferential direction.

[0113] Furthermore, in the above-described first to third embodiments, the outer diameter side dynamic pressure generating groove 12 and the outer diameter side reverse dynamic pressure generating groove 13 are arranged on the outer diameter side of the outer diameter side deep groove 14, and the inner diameter side dynamic pressure generating groove 15 and the inner diameter side reverse dynamic pressure generating groove 16 are arranged on the inner diameter side of the inner diameter side deep groove 17, but these arrangements can be freely changed. For example, the outer diameter side dynamic pressure generating groove and the outer diameter side reverse dynamic pressure generating groove may be arranged on the inner diameter side of the outer diameter side deep groove, and the inner diameter side dynamic pressure generating groove and the inner diameter side reverse dynamic pressure generating groove may be arranged on the outer diameter side of the inner diameter side deep groove.

[0114] Furthermore, in the first to third embodiments, one deep groove is connected to one dynamic pressure generating groove, but a plurality of deep grooves may be connected to one dynamic pressure generating groove.

[0115] Furthermore, the dynamic pressure generating groove is not limited to being in communication with the deep groove, and the upstream end of the dynamic pressure generating groove in the relative rotation direction may be disposed in a non-communicating state near the circumferential end of the deep groove. Note that it is preferable that the upstream end of the dynamic pressure generating groove in the relative rotation direction overlaps with the deep groove in the radial direction.

[0116] Furthermore, in Examples 1 to 3, the downstream end of the dynamic pressure generating groove in terms of relative rotation is disposed between circumferentially adjacent deep grooves, but the deep groove of the dynamic pressure generating mechanism may overlap radially with the downstream end of the dynamic pressure generating groove upstream of the dynamic pressure generating mechanism.

[0117] Furthermore, the outer diameter side dynamic pressure generating groove, outer diameter side reverse dynamic pressure generating groove, inner diameter side dynamic pressure generating groove, and inner diameter side reverse dynamic pressure generating groove are not limited to the shapes described in Examples 1 to 3, and may be Rayleigh step grooves, spiral grooves, etc., and can be freely modified. Furthermore, the shape of their terminal ends can also be freely modified.

[0118] In addition, in the above-described first to third embodiments, the dynamic pressure generating element is provided on the outer diameter side, but the dynamic pressure generating element may be omitted, or the dynamic pressure generating element may be provided on the inner diameter side or on both radial sides. Furthermore, the number of dynamic pressure generating elements can be freely changed.

[0119] Furthermore, in the first to third embodiments, the outer diameter side dynamic pressure generating mechanism and the inner diameter side dynamic pressure generating mechanism are bi-directionally rotatable, but they may be unidirectionally rotatable.

[0120] For example, a single-rotation compatible configuration may be used as shown in Fig. 8. A sliding surface 111 of the stationary seal ring 110 is provided with a dynamic pressure generating mechanism 100A and a dynamic pressure generating mechanism 100B.

[0121] The dynamic pressure generating mechanism 100A is composed of an outer diameter side dynamic pressure generating groove 112 and an outer diameter side deep groove 114. The outer diameter side dynamic pressure generating groove 112 communicates with the outer diameter side of a circumferential end portion 114a on the downstream side of the outer diameter side deep groove 114 in terms of relative rotation, and extends downstream of the relative rotation. Note that the circumferential end portion 114b on the upstream side of the outer diameter side deep groove 114 in terms of relative rotation is surrounded by a land portion L, and is isolated from the outer space S1, the inner space S2, and other grooves.

[0122] The dynamic pressure generating mechanism 100B is composed of an inner diameter side dynamic pressure generating groove 115 and an inner diameter side deep groove 117. The inner diameter side dynamic pressure generating groove 115 communicates with the inner diameter side of a circumferential end portion 117a on the downstream side of the inner diameter side deep groove 117 in terms of relative rotation, and extends downstream of the relative rotation. Note that a circumferential end portion 117b on the upstream side of the inner diameter side deep groove 117 in terms of relative rotation is surrounded by a land portion L, and is isolated from the outer space S1, the inner space S2, and other grooves.

[0123] Furthermore, in Examples 2 and 3, a form was exemplified in which no grooves such as pressure release grooves were formed near the ends of the dynamic pressure generating grooves, but a groove such as pressure release grooves may also be formed near the ends of the dynamic pressure generating grooves.

[0124] Furthermore, in the first to third embodiments, a mechanical seal has been described as an example of the sliding component, but other mechanical seals for general industrial machinery, automobiles, water pumps, etc. may also be used. Furthermore, the sliding component is not limited to a mechanical seal, and may be a sliding bearing or other sliding component other than a mechanical seal.

[0125] DESCRIPTION OF SYMBOLS 1 Rotating shaft 4 Housing 10 Stationary seal ring 11 Sliding surface 12 Outer diameter side dynamic pressure generating groove 12c End 13 Outer diameter side reverse dynamic pressure generating groove 13c End 14 Outer diameter side deep grooves 14a, 14b Circumferential end 15 Inner diameter side dynamic pressure generating groove 15c End 16 Inner diameter side reverse dynamic pressure generating groove 16c End 17 Inner diameter side deep grooves 17a, 17b Circumferential end 19 Dynamic pressure generating element 20 Rotating seal ring 21 Sliding surface 30 Recovery groove (pressure release groove) 40 Outer diameter side arc-shaped groove (storage groove) 50 Inner diameter side arc-shaped groove (storage groove) 124a Radial groove A, B Dynamic pressure generating mechanism F1 First fluid F2 Second fluid S1 Outer space (outer diameter space) S2 Inner space (inner diameter space)

Claims

1. A sliding component in which the sliding surfaces of a pair of sliding rings rotate relative to each other to define an outer diameter space and an inner diameter space, wherein at least one of the sliding surfaces is provided with a dynamic pressure generating groove extending in the circumferential direction, and a deep groove extending in the circumferential direction, the circumferential end portion of which on the downstream side in terms of relative rotation communicates with the upstream end portion of one of the dynamic pressure generating grooves in terms of relative rotation.

2. The sliding component according to claim 1, wherein the dynamic pressure generating groove comprises an inner diameter side dynamic pressure generating groove and an outer diameter side dynamic pressure generating groove arranged outer diameter side of the inner diameter side dynamic pressure generating groove, and the deep groove comprises an inner diameter side deep groove arranged outer diameter side of the inner diameter side dynamic pressure generating groove, having a circumferential end on the downstream side of relative rotation in the circumferential direction and communicating with the upstream end of the inner diameter side dynamic pressure generating groove, and an outer diameter side deep groove arranged inner diameter side of the outer diameter side dynamic pressure generating groove, having a circumferential end on the downstream side of relative rotation in the circumferential direction and communicating with the upstream end of the outer diameter side dynamic pressure generating groove.

3. A sliding component according to claim 1, wherein the circumferential end of said deep groove is directly connected to a side wall of the upstream end of said hydrodynamic groove in relative rotation in the radial direction.

4. A sliding component as described in claim 2, wherein at least one of the downstream end of the inner diameter side dynamic pressure generating groove for relative rotation and the downstream end of the outer diameter side dynamic pressure generating groove for relative rotation is tapered in the inner diameter direction or the outer diameter direction when viewed in the axial direction.

5. A sliding component according to claim 2, wherein a pressure relief groove is provided between said inner diameter side deep groove and said outer diameter side deep groove, and extends in the circumferential direction.

6. A sliding component according to claim 1, wherein a retention groove is provided on the circumferential extension of said deep groove.

7. A sliding component according to claim 1, wherein the downstream end of the hydrodynamic groove in relation to relative rotation is disposed between the deep grooves adjacent to each other in the circumferential direction.

8. A sliding component as set forth in claim 1, further comprising a counter dynamic pressure generating groove extending circumferentially opposite to said dynamic pressure generating groove, said deep groove having a circumferential end communicating with an upstream end of said counter dynamic pressure generating groove in terms of relative rotation.

9. The sliding component according to claim 1, further comprising a dynamic pressure generating element communicating with the outer diameter space or the inner diameter space.

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