Mechanical seal

Abstract

Provided is a sliding member in which leakage of a fluid to be sealed is reduced and sliding surfaces can be equally separated from each other. A supply hole (10b) for supplying a spacer fluid (G) between the sliding surfaces (11, 21) is formed in at least one of the sliding surfaces (11, 21) of the pair of seal rings (10, 20), an introduction groove (23) that overlaps the supply hole (10b) in the axial direction and extends in the circumferential direction is formed in the sliding surface (21), and a bypass groove (25) that extends toward the introduction groove (23) at both ends (252, 253) in the circumferential direction is formed at a position closer to the leakage side (S2) than the introduction groove (23).

Description

Technical Field

[0001] The present invention relates to relatively rotating sliding parts, for example, to a mechanical seal used in a shaft sealing device for sealing a rotating shaft of a rotating machine in an automobile, general industrial machinery, or other sealing fields. Background Art

[0002] As a shaft sealing device that prevents leakage of a sealed fluid, for example, a mechanical seal includes a pair of annular sliding members that rotate relative to each other and slide against each other. In recent years, for environmental reasons, it has been desired to reduce energy lost due to sliding in such mechanical seals.

[0003] For example, the mechanical seal disclosed in Patent Document 1 has a fluid supply passage formed in a stationary seal ring, connecting the sealing surface with an external fluid supply source. Furthermore, the rotating seal ring is provided with: a circumferentially extending fluid guide groove, into which a gas such as nitrogen is introduced from the fluid supply passage; a plurality of dynamic pressure generating grooves extending from the fluid guide groove toward the high-pressure side; and a plurality of dynamic pressure generating grooves extending from the fluid guide groove toward the low-pressure side.

[0004] When gas is supplied from the fluid supply source, it flows into the fluid guide grooves and, through the dynamic pressure-generating grooves on the high- and low-pressure sides, is evenly distributed as static pressure in the circumferential and radial directions between the opposing sliding surfaces. This static pressure separates the sliding surfaces from each other. Furthermore, during relative rotation, dynamic pressure is generated in the dynamic pressure-generating grooves in addition to the static pressure, further separating the sliding surfaces and effectively reducing friction during relative rotation.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-022834 (page 6, Figure 3 ) Summary of the Invention

[0008] Problems to be solved by the invention

[0009] In a mechanical seal such as that disclosed in Patent Document 1, while the dynamic pressure-generating grooves on the high-pressure and low-pressure sides generate substantially equal static and dynamic pressures in the circumferential and radial directions between the opposing sliding surfaces, thus maintaining a balanced separation between the sliding surfaces, the structure is susceptible to gas leakage from the low-pressure dynamic pressure-generating grooves to the low-pressure side. Consequently, there is a risk that the sealed fluid on the high-pressure side will leak into the low-pressure space along with the gas that leaks from the low-pressure dynamic pressure-generating grooves between the sliding surfaces.

[0010] The present invention has been made in view of such problems, and an object of the present invention is to provide a sliding component that reduces leakage of a sealed fluid and enables sliding surfaces to be separated from each other in a balanced manner.

[0011] Means for solving problems

[0012] In order to solve the above-mentioned problems, the mechanical seal of the present invention is arranged between a housing and a rotating shaft that rotates relative to the housing. A stationary sealing ring fixed to the housing side and a rotating sealing ring fixed to the rotating shaft side rotate relative to each other. The mechanical seal divides a sealed fluid space from a leakage space, and a supply hole for supplying an isolation fluid between the sliding surfaces is formed on the sliding surface of at least one of a pair of the sealing rings. An inlet groove that overlaps with the supply hole in the axial direction and extends circumferentially is formed on the sliding surface of at least one of the pair of sliding rings, wherein a bypass groove with both circumferential ends extending toward the inlet groove is formed at a position closer to the leakage side than the inlet groove.

[0013] Thus, the bypass groove extending from the leakage side toward the introduction groove recovers the fluid on the leakage side of the introduction groove, thereby reducing leakage of the sealed fluid and enabling the sliding surfaces to be separated in a balanced manner.

[0014] It can also be that the bypass groove has inclined portions at both ends in the circumferential direction, the inclined portion located on the upstream side in the relative rotation direction is inclined toward the upstream side of the inlet groove in the relative rotation direction, and the inclined portion located on the downstream side in the relative rotation direction is inclined toward the downstream side of the inlet groove in the relative rotation direction.

[0015] This makes it easier to introduce the isolation fluid between the bypass groove and the introduction groove. In addition, positive pressure is generated at the leakage side end of the upstream inclined portion, and negative pressure is generated at the downstream inclined portion, so the leakage side also floats evenly and the fluid flowing out to the leakage side is easily recovered.

[0016] A peripheral portion extending in the circumferential direction may be provided between the upstream inclined portion and the downstream inclined portion in the circumferential direction.

[0017] Thus, the peripheral portion extending in the circumferential direction serves as a negative pressure generating portion, making it easier to recover the fluid that has flowed out to the leakage side of the introduction groove when the pair of slide rings rotate relative to each other.

[0018] Alternatively, both ends of the bypass groove are communicated with the introduction groove.

[0019] Thus, the spacer fluid can be introduced from the introduction groove to the bypass groove to separate the sliding surfaces from each other both when the pair of slide rings are relatively rotating and when they are stationary.

[0020] A branch groove may extend from the introduction groove toward the sealed fluid side.

[0021] This allows balanced pressure to be generated in the radial direction, and the sliding surfaces to be separated from each other in a stable manner.

[0022] The branch groove may include a dynamic pressure generating portion extending in a relative rotation direction of the pair of seal rings.

[0023] This increases the buoyancy between the sliding surfaces by utilizing the dynamic pressure generated during relative rotation in addition to the static pressure of the barrier fluid. Furthermore, a large amount of barrier fluid can be discharged toward the sealed fluid, thereby suppressing leakage of the sealed fluid into the leakage space.

[0024] The branch groove may be arranged between both ends of the bypass groove in the circumferential direction.

[0025] Thus, since the bypass groove and the branch groove are provided at a position where they overlap in the radial direction, the sliding surfaces can be separated from each other more stably.

[0026] Alternatively, the introduction groove is in an endless ring shape.

[0027] This allows for balanced pressure generation in the circumferential direction, allowing the sliding surfaces to be separated stably. Furthermore, during rotation, dynamic pressure is less likely to be generated locally in the circumferential direction of the guide groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a longitudinal sectional view showing an example of a mechanical seal according to Example 1 of the present invention.

[0029] Figure 2 This is a diagram showing the sliding surface of the rotary seal ring of Example 1 as viewed from the axial direction.

[0030] Figure 3 yes Figure 2 A partial enlarged view of .

[0031] Figure 4 (a) is a cross-sectional view along line AA, Figure 4 (b) is a cross-sectional view along line BB.

[0032] Figure 5 (a) is a schematic diagram showing the state of static pressure acting on the sliding surface of Example 1, Figure 5 (b) is a schematic diagram showing the state of the dynamic pressure acting on the sliding surface in the same manner.

[0033] Figure 6 This is a diagram showing the sliding surface of a rotary seal ring according to Example 2 of the present invention as viewed from the axial direction.

[0034] Figure 7 yes Figure 6 A partial enlarged view of .

[0035] Figure 8 (a) is a cross-sectional view along line CC, Figure 8 (b) is a cross-sectional view along line DD.

[0036] Figure 9 (a) is a schematic diagram showing the state of static pressure acting on the sliding surface of Example 2. Figure 9 (b) is a schematic diagram showing the state of the dynamic pressure acting on the sliding surface in the same manner.

[0037] Figure 10 This is a diagram showing the introduction groove and branch grooves according to Example 3 of the present invention as viewed from the axial direction.

[0038] Figure 11 This is a diagram showing the introduction groove and the branch groove according to Example 4 of the present invention as viewed from the axial direction.

[0039] Figure 12 This is a diagram showing the introduction groove and branch grooves according to Example 5 of the present invention as viewed from the axial direction.

[0040] Figure 13 This is a diagram of the introduction groove and the branch groove according to Example 6 of the present invention as viewed from the axial direction.

[0041] Figure 14 This is a diagram of the introduction groove and the branch groove according to Example 7 of the present invention as viewed from the axial direction. DETAILED DESCRIPTION

[0042] Hereinafter, modes for implementing the mechanical seal of the present invention will be described based on examples.

[0043] Example 1

[0044] Reference Figures 1 to 5 The mechanical seal of Example 1 will be described.

[0045] Figure 1 The mechanical seal shown is an inside type mechanical seal that seals a sealed fluid F that leaks from the outer diameter side to the inner diameter side of a sliding surface.

[0046] Specifically, a sealed fluid F exists in the outer space S1 of the mechanical seal, and atmosphere A exists in the inner space S2. In this embodiment, the outer diameter side of the sliding member constituting the mechanical seal is described as the sealed fluid space side (high-pressure side), and the inner diameter side is described as the leakage space side (low-pressure side). Furthermore, for ease of explanation, grooves formed on the sliding surface are sometimes indicated with dots in the drawings.

[0047] The mechanical seal mainly consists of an annular rotating seal ring 20, which serves as one sliding ring, and an annular stationary seal ring 10, which serves as the other sliding ring. The rotating seal ring 20 is mounted on the rotating shaft 1 via a sleeve 2, so that it can rotate along with the rotating shaft 1. The stationary seal ring 10 is mounted on the inner diameter side of the housing 4 of the device to be mounted, so that it does not rotate but can move in the axial direction.

[0048] Two O-rings 5 ​​are axially spaced apart between the housing 4 and the stationary seal ring 10. The housing 4 is formed with a through-hole 4a extending radially therethrough. The inner opening of the through-hole 4a communicates with a space 6 defined by the housing 4, the stationary seal ring 10, and the two O-rings 5, while the outer opening of the through-hole 4a communicates with an external static pressure gas supply source 9. Furthermore, a cover 8 is secured to the housing 4, located on the side of the stationary seal ring 10 opposite the rotating seal ring 20.

[0049] An elastic member 7 is disposed between the cover 8 and the stationary seal ring 10. The stationary seal ring 10 is biased in the axial direction by the elastic member 7, and the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotating seal ring 20 slide in close contact with each other.

[0050] Furthermore, the stationary seal ring 10 is formed with a plurality of passages 10a extending from the outer peripheral surface to the sliding surface 11 in the circumferential direction. The openings at one end of the passages 10a communicate with the space 6, while the openings at the other end, i.e., the supply holes 10b, communicate with the introduction grooves 23 (described later) of the rotary seal ring 20. Furthermore, the sliding surface 11 of the stationary seal ring 10 is formed as a flat surface except for the supply holes 10b.

[0051] The stationary seal ring 10 and the rotating seal ring 20 are typically formed from a combination of SiC (hard material) and SiC (hard material) or a combination of SiC (hard material) and carbon (soft material), but are not limited to these. Any sliding material that can be used as a sliding material for mechanical seals can be used. SiC includes materials composed of two or more phases with different components and compositions, such as sintered bodies containing boron, aluminum, carbon, etc. as sintering aids. Examples include SiC with dispersed graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, and SiC-TiN. Carbon includes resin-molded carbon and sintered carbon, such as carbon mixed with carbonaceous and graphite. In addition to the aforementioned sliding materials, metal materials, resin materials, surface-modified materials (coating materials), and composite materials can also be used.

[0052] like Figure 2 and Figure 3 As shown, the rotary seal ring 20 is slidable clockwise and counterclockwise relative to the stationary seal ring 10 as the counterpart seal ring. Figure 2 and Figure 3 The solid arrows and dashed arrows in FIG. 1 show the relative rotation direction of the stationary seal ring 10 relative to the rotating seal ring 20. Figure 2 and Figure 3 The direction of the solid arrow is called the forward direction, and the direction of the dotted arrow is called the reverse direction.

[0053] The sliding surface 21 of the rotary seal ring 20 is provided with an introduction groove 23 and a plurality of bypass grooves 25. The portion other than the introduction groove 23 and the bypass grooves 25 is a flat land portion 22. The portion of the inner diameter portion of the rotary seal ring 20 into which the sleeve 2 fits is not shown.

[0054] The introduction groove 23 is provided concentrically with the rotary seal ring 20. That is, the introduction groove 23 is in the shape of an endless circular ring.

[0055] On the inner diameter side of the introduction groove 23 , bypass grooves 25 (e.g., eight in this embodiment) are evenly arranged in the circumferential direction.

[0056] The bypass groove 25 is substantially U-shaped when viewed in the axial direction. Specifically, the bypass groove 25 is composed of a peripheral portion 251 and inclined portions 252 and 253. The bypass groove 25 as a whole is shaped such that the circumference is longer in the circumferential direction than in the radial direction.

[0057] The peripheral edge portion 251 extends in the circumferential direction at a position farther inward from the introduction groove 23 . The peripheral edge portion 251 is substantially parallel to the introduction groove 23 .

[0058] The inclined portions 252 and 253 extend from both ends of the peripheral portion 251 toward the introduction groove 23 in directions separating from each other. The inclined portions 252 and 253 are connected to the introduction groove 23. More specifically, the inclined portion 252 is located on the upstream side in the direction of normal rotation. The inclined portion 252 has a pair of circumferential walls. These pair of walls extend linearly from the peripheral portion 251 toward the introduction groove 23 in the radial direction and from the peripheral portion 251 toward the upstream side in the direction of normal rotation in the circumferential direction. In other words, the inclined portion 252 extends linearly from the peripheral portion 251 toward the introduction groove 23 in the direction of normal rotation, obliquely toward the upstream side in the direction of normal rotation. The inclined portion 253 is located on the downstream side in the direction of normal rotation. The inclined portion 253 has a pair of circumferential walls. These pair of walls extend linearly from the peripheral portion 251 toward the introduction groove 23 in the radial direction and from the peripheral portion 251 toward the downstream side in the direction of normal rotation in the circumferential direction. That is, the inclined portion 253 extends linearly from the peripheral portion 251 toward the introduction groove 23, slanting downstream in the forward rotation direction. Furthermore, during reverse rotation, the upstream and downstream directions of the inclined portions 252 and 253 become opposite, but even in this case, the inclination directions remain the same. That is, the upstream inclined portion inclines upstream, and the downstream inclined portion inclines downstream. Furthermore, the pair of circumferential walls forming the inclined portion 252 and the pair of circumferential walls forming the inclined portion 253 may also have shapes other than linear, for example, curved, bent, or folded.

[0059] The bypass groove 25 has a symmetrical shape with respect to a line α extending in the radial direction and passing through the circumferential center of the peripheral portion 251. In the following description, the line α extending in the radial direction will be simply referred to as a radial line α.

[0060] like Figure 4 As shown in (a), the depth D1 of the introduction groove 23 is deeper than the depth D2 of the inclined portion 253 (D1>D2). Specifically, the depth D1 is about twice the depth D2.

[0061] And, as Figure 4 As shown in FIG. 2( b ), the depth D2 of the inclined portion 253 is the same as the depth D2 ′ of the peripheral portion 251 and the depth D2 ″ of the inclined portion 232 ( D2 = D2 ′ = D2 ″). That is, the bypass groove 25 has a constant depth.

[0062] Next, the pressure acting on the sliding surface 11 of the stationary seal ring 10 and the sliding surface 21 of the rotary seal ring 20 will be described.

[0063] When the static pressure gas G as the isolation fluid is supplied from the static pressure gas supply source 9, the static pressure gas G passes through the through hole 4a of the housing 4, the space 6, the passage 10a of the stationary seal ring 10, and the supply hole 10b and is introduced into the introduction groove 23 of the rotating seal ring 20 (see FIG. Figure 1 ). In addition, the static pressure gas G is at a higher pressure than the sealed fluid F.

[0064] like Figure 5 As shown in (a), the static pressure gas G introduced into the inlet groove 23 flows into each bypass groove 25. As a result, the static pressure of the static pressure gas G acts on the sliding surfaces 11 and 21, separating them axially. This static pressure acts not only in the inlet groove 23 but also in the bypass grooves 25 that branch radially from the inlet groove 23. This allows for a balanced separation between the sliding surfaces 11 and 21. Furthermore, the static pressure of the static pressure gas G prevents the sealed fluid F that flows between the sliding surfaces 11 and 21 from moving radially inward.

[0065] And, as Figure 5 As shown in (b) of FIG. 2 , when the sliding surfaces 11 and 21 rotate relative to each other in the forward direction, the static pressure gas G in the inlet groove 23 and the bypass groove 25 moves in the forward direction. In the bypass groove 25, the static pressure gas G flows from the inlet groove 23 into the inclined portion 252, flows through the peripheral portion 251, and then flows through the inclined portion 253 before returning to the inlet groove 23.

[0066] The flow of the static pressure gas G in the bypass groove 25 caused by shear can be used to recover the fluid on the inner diameter side of the introduction groove 23, so the static pressure gas G is unlikely to leak into the inner space S2. Therefore, the sealed fluid F is unlikely to leak into the inner space S2 along with the static pressure gas G.

[0067] Specifically, because the fluid within the inclined portion 253 is drawn into the main flow of static pressure gas G within the inlet groove 23, a relative negative pressure is generated within the inclined portion 253 on the downstream side of the bypass groove 25 and within the peripheral edge 251. Meanwhile, because the static pressure gas G within the inlet groove 23 flows into the inclined portion 252 on the upstream side of the bypass groove 25, its relative pressure becomes higher than that within the inclined portion 253 and the peripheral edge 251. Consequently, the peripheral edge 251, which has generated a relative negative pressure within the bypass groove 25, recovers the fluid in its vicinity. Furthermore, although the peripheral edge 251 and the inclined portion 253 have a relative negative pressure relative to the inclined portion 252, the static pressure of the static pressure gas G within the inlet groove 23 and the inclined portion 252 dominates, and thus has little influence on the force separating the sliding surfaces 11 and 21.

[0068] Furthermore, the flow of the static pressure gas G within the bypass groove 25 is relatively faster in the peripheral portion 251 compared to the inclined portions 252 and 253. This is because the extending directions of the inclined portions 252 and 253 intersect the direction of the shear force, making the influence of the shear force relatively smaller in the inclined portions 252 and 253 compared to the peripheral portion 251. Furthermore, the flow in the inclined portion 252 is hindered by the inflection point between the inclined portion 252 and the peripheral portion 251. Furthermore, the flow in the inclined portion 253 is hindered by the static pressure within the introduction groove 23. Consequently, the flow in the inclined portions 252 and 253 is slower than in the peripheral portion 251.

[0069] Furthermore, the inclined portion 252 of the bypass groove 25 is inclined from the peripheral portion 251 toward the introduction groove 23 in the reverse rotation direction, while the inclined portion 253 is inclined from the peripheral portion 251 toward the introduction groove 23 in the forward rotation direction. Therefore, during forward rotation, static-pressure gas G is easily introduced from the introduction groove 23 into the inclined portion 252, and static-pressure gas G is easily discharged from the inclined portion 253 into the introduction groove 23. Furthermore, dynamic pressure is generated near the leakage-side end 252a of the inclined portion 252 on the upstream side in the forward rotation direction, that is, near the inflection point between the inclined portion 252 and the peripheral portion 251. This allows for balanced buoyancy even on the leakage side.

[0070] Furthermore, the static pressure gas G returns toward the introduction groove 23 from a position radially inner than the introduction groove 23 , and therefore the static pressure gas G is less likely to leak from the inner space S2 .

[0071] Furthermore, the inclined portions 252 and 253 communicate with the introduction groove 23, making it easy to introduce and withdraw the static-pressure gas G between the inclined portions 252 and 253 and the introduction groove 23. Furthermore, even when the relative sliding of the sliding surfaces 11 and 21 stops, the static-pressure gas G can be introduced from the introduction groove 23 into the bypass groove 25, thereby enabling the sliding surfaces 11 and 21 to be separated from each other.

[0072] Furthermore, the inclined portions 252 and 253 extend linearly without any inflection points, allowing the static pressure gas G to flow smoothly within the inclined portions 252 and 253. Therefore, dynamic pressure is less likely to be generated near the inclined portions 252 and 253 during relative rotation, thereby reducing leakage of the static pressure gas G into the inner space S2.

[0073] Furthermore, the annular introduction groove 23 generates pressure evenly in the circumferential direction, stably separating the sliding surfaces 11 and 21. Furthermore, dynamic pressure is less likely to be generated locally in the circumferential direction of the introduction groove 23 during relative rotation.

[0074] Furthermore, the bypass groove 25 is symmetrical about the radial line α, so the fluid recovery capability of the bypass groove 25 does not change depending on the rotational direction of the rotary seal ring 20. Furthermore, during reverse rotation, dynamic pressure can be generated near the leakage-side end 253a of the inclined portion 253 on the upstream side of the reverse rotation direction, that is, near the inflection point between the inclined portion 253 and the peripheral portion 251.

[0075] In this embodiment, the depth D1 of the introduction groove 23 is approximately twice the depth D2 of the inclined portion 253. However, the depths can be freely changed. For example, the depth D2 can be the same as the depth D1 or deeper than the depth D2.

[0076] Furthermore, in this embodiment, the bypass groove 25 is exemplified as having a constant depth, but the depth of the bypass groove 25 may be different in the extending direction.

[0077] Furthermore, in this embodiment, both ends of the peripheral portion 251 are inclined portions 252 and 253 , but both ends of the peripheral portion 251 may also extend in the radial direction.

[0078] Furthermore, in the present embodiment, the bypass groove 25 is exemplified as having a symmetrical shape with respect to the radial line α, but may also have an asymmetrical shape with respect to the radial line.

[0079] Example 2

[0080] Next, refer to Figures 6 to 9 A mechanical seal according to Example 2 will be described. Note that redundant descriptions of the same structures as those of Example 1 will be omitted.

[0081] like Figure 6 and Figure 7 As shown, the sliding surface 221 of the rotary seal ring 220 of the second embodiment is provided with an introduction groove 223, outer diameter side dynamic pressure generating mechanisms 224 and 224' as branch grooves, and a bypass groove 225. The introduction groove 223 and the bypass groove 225 have the same structure as the introduction groove 23 and the bypass groove 25 of the first embodiment.

[0082] On the outer diameter side of the introduction groove 223, groups of outer diameter side dynamic pressure generating mechanisms 224, 224' (e.g., eight groups in this embodiment) are evenly arranged along the circumferential direction. The outer diameter side dynamic pressure generating mechanisms 224, 224' are circumferentially arranged between the inclined portions 225A, 225B at both ends of the bypass groove 225.

[0083] The outer diameter-side dynamic pressure generating mechanism 224 has a so-called Rayleigh step shape and is composed of a radial groove 224A and a circumferential groove 224B, which serves as a dynamic pressure generating portion. The radial groove 224A extends radially outward from the introduction groove 223. The circumferential groove 224B extends from the outer diameter end of the radial groove 224A in the forward rotation direction, approximately parallel to the introduction groove 223.

[0084] The outer diameter side dynamic pressure generating mechanism 224' is arranged in a reverse direction away from the outer diameter side dynamic pressure generating mechanism 224. The outer diameter side dynamic pressure generating mechanism 224' is symmetrical with the outer diameter side dynamic pressure generating mechanism 224 with respect to the radial line α.

[0085] like Figure 8 As shown in (a) of FIG. 2 , the depth D10 of the introduction groove 223 is equal to the depth D20 of the radial groove 224A of the outer diameter side dynamic pressure generating mechanism 224 ( D10 = D20 ).

[0086] Furthermore, the depth D20 of the radial groove 224A is greater than the depth D30 of the bypass groove 225 (D20>D30). Specifically, the depth D30 is approximately 1 / 2 times the depth D20. The depth D30 can be freely changed as long as it is shallower than the depth D20.

[0087] like Figure 8 As shown in FIG. 2( b ), the bottom surface 224 b of the circumferential groove 224B is an inclined surface that gradually becomes shallower from the bottom surface 224 a of the radial groove 224A toward the land portion 222 .

[0088] like Figure 9 As shown in (a), the static-pressure gas G introduced into the inlet groove 223 flows into the outer-diameter-side dynamic pressure generating mechanisms 224, 224' and the bypass grooves 225. As a result, the static pressure of the static-pressure gas G acts on the sliding surfaces 11 and 21, separating them axially. This static pressure acts not only on the inlet groove 223 but also on the outer-diameter-side dynamic pressure generating mechanisms 224, 224' and the bypass grooves 225 that branch radially from the inlet groove 23. This allows for a balanced separation between the sliding surfaces 11 and 21.

[0089] And, as Figure 9 As shown in (b) of FIG. 1 , when the sliding surfaces 11 and 21 rotate relative to each other in the forward rotation direction, the static pressure gas G within the introduction groove 223, the outer diameter-side dynamic pressure generating mechanisms 224 and 224', and the bypass groove 225 moves in the forward rotation direction. This generates dynamic pressure near the end 224c of the circumferential groove 224B and near the leakage-side end 225a of the inclined portion 225A on the upstream side of the bypass groove 225 in the forward rotation direction, i.e., the intersection of the inclined portion 225A and the peripheral edge 225C. This allows the fluid surrounding the bypass groove 225 to be recovered. In other words, in addition to the static pressure of the static pressure gas G, dynamic pressure also acts on the sliding surfaces 11 and 21 at locations closer to the sealed fluid and leakage sides than the introduction groove 223, thereby further separating the sliding surfaces 11 and 21 from each other.

[0090] Furthermore, the groove capacity V224, V224' of the outer diameter side dynamic pressure generating mechanism 224, 224' is larger than the groove capacity V225 of the bypass groove 225, so that sufficient static pressure gas G can flow out from one of the outer diameter side dynamic pressure generating mechanisms 224, 224' to between the sliding surfaces 11, 21, and the sealed fluid F flowing into between the sliding surfaces 11, 21 can be suppressed from moving toward the inner diameter side.

[0091] Furthermore, the outer-diameter-side dynamic pressure generating mechanisms 224 and 224' are positioned between the inclined portions 225A and 225B at either end of the bypass groove 225. In other words, the outer-diameter-side dynamic pressure generating mechanisms 224 and 224' are positioned radially overlapping with the bypass groove 225. This allows pressure to be generated at the radially overlapping position, thereby more stably separating the sliding surfaces 11 and 21 from each other.

[0092] Furthermore, during forward rotation, dynamic pressure can be generated in the outer diameter-side dynamic pressure generating mechanism 224, and during reverse rotation, dynamic pressure can be generated near the leakage-side end 225b of the inclined portion 225B on the reversely upstream side of the bypass groove 225, that is, the intersection of the inclined portion 225B and the peripheral edge portion 225C. In other words, dynamic pressure can be generated regardless of the rotation direction of the rotary seal ring 220.

[0093] In the second embodiment, the outer diameter side dynamic pressure generating mechanisms 224 and 224 ′ are arranged between the inclined portions 225A and 225B at both ends of the bypass groove 225 . However, the branch grooves may be arranged circumferentially offset from the bypass grooves.

[0094] Furthermore, in this second embodiment, the outer diameter side dynamic pressure generating means 224, 224' is illustrated as being composed of radial grooves 224A and circumferential grooves 224B, but for example, a spiral groove having circumferential and radial components may also be used. Furthermore, the branch grooves may be composed only of radial grooves.

[0095] Example 3

[0096] Next, refer to Figure 10 A mechanical seal according to Example 3 will be described. Note that redundant descriptions of the same structures as those of Example 2 will be omitted.

[0097] like Figure 10 As shown, in the rotary seal ring 320 of the third embodiment, the radial grooves 324A and 324A' of the outer diameter side dynamic pressure generating mechanisms 324 and 324' and the inclined portions 325A and 325B at both ends of the bypass groove 325 do not communicate with the introduction groove 323. Furthermore, the outer diameter side dynamic pressure generating mechanisms 324 and 324' of the present embodiment are formed to a constant depth.

[0098] Specifically, the radial width L40 of the land portion 322a defining the radial groove 324A and the introduction groove 323 is shorter than the radial width L50 of the introduction groove 323 (L40<L50). The radial width L40 only needs to be shorter than the radial width L50, and is preferably 1 / 5 times or less.

[0099] Similarly, radial width L41 of land portion 322b defining the inclinations 325A and 325B and the introduction groove 323 is shorter than radial width L50 of the introduction groove 323 (L41 < L50). Radial width L41 only needs to be shorter than radial width L50, and is preferably 1 / 5 times or less.

[0100] As a result, the static pressure gas G passes over the land portions 322 a and 322 b and is supplied from the introduction groove 423 to the outer diameter side dynamic pressure generating mechanisms 324 and 324 ′ and the bypass groove 325 .

[0101] Thus, in the mechanical seal of the present invention, as for the branch grooves and bypass grooves connected to the inlet groove at both ends, as long as the static pressure gas can be substantially moved between the inlet groove and the branch grooves and bypass grooves, the branch grooves and bypass grooves may not be connected to the inlet groove as in the present embodiment.

[0102] Example 4

[0103] Next, refer to Figure 11 A mechanical seal according to Example 4 will be described. Note that redundant descriptions of the same structures as those of Example 2 will be omitted.

[0104] like Figure 11 As shown, the bypass groove 425 of the rotary seal ring 420 of the fourth embodiment is V-shaped when viewed in the axial direction.

[0105] Specifically, in the bypass groove 425, inclined portions 425A and 425B extend in directions away from each other from a top portion 425C located approximately in the circumferential center toward the introduction groove 423. That is, the bypass groove 425 of the fourth embodiment does not have the peripheral edge portion 251 of the first embodiment.

[0106] As described above, the mechanical seal of the present invention only needs to be able to move the barrier fluid between the introduction groove and the bypass groove, and the shape of the bypass groove can be freely changed as in this embodiment.

[0107] Example 5

[0108] Next, refer to Figure 12 A mechanical seal according to Example 5 will be described. Note that redundant descriptions of the same structures as those of Example 2 will be omitted.

[0109] like Figure 12As shown, the rotary seal ring 520 of the fifth embodiment is provided with an outer diameter side dynamic pressure generating mechanism 524 , but is not provided with the outer diameter side dynamic pressure generating mechanism 224 ′ of the second embodiment.

[0110] In this way, the mechanical seal of the present invention can also cope with the forward rotation direction.

[0111] Example 6

[0112] Next, refer to Figure 13 A mechanical seal according to Example 6 will be described. Note that redundant descriptions of the same structures as those of Example 2 will be omitted.

[0113] like Figure 13 As shown, in the rotary seal ring 620 of the sixth embodiment, the introduction groove 623 is divided at one location in the circumferential direction. Thus, the introduction groove 623 is not limited to a circular groove, but may also be substantially C-shaped.

[0114] Furthermore, the introduction groove is not limited to the C-shape, and may be divided into a plurality of parts in the circumferential direction, or may be an annular wave shape or an annular polygonal shape.

[0115] Example 7

[0116] Next, refer to Figure 14 A mechanical seal according to Example 7 will be described. Note that redundant descriptions of the same structures as those of Example 2 will be omitted.

[0117] The mechanical seal to which the rotary seal ring 720 of the seventh embodiment is applied is an outer-type mechanical seal that allows the atmosphere A to communicate with the outer space S1 of the sliding surface 721 and seals the sealed fluid F on the inner space S2 side.

[0118] In the seventh embodiment, the dynamic pressure generating mechanisms 724 and 724 ′ are arranged on the inner diameter side of the introduction groove 723 , and the bypass groove 725 is arranged on the outer diameter side of the introduction groove 723 .

[0119] As described above, the mechanical seal of the present invention can also be used in an environment where the sealed fluid space is located on the inner diameter side of the sliding surface and the leakage space is located on the outer diameter side of the sliding surface.

[0120] While 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 modifications and additions within the scope that do not depart from the gist of the present invention are also included in the present invention.

[0121] For example, in the above-mentioned embodiments 1 to 7, the mechanical seal for industrial machinery was described as an example, but other mechanical seals such as those for automobiles may also be used.

[0122] Furthermore, in the above-mentioned embodiments 1 to 7, the sealed fluid is described as a high-pressure gas, but the present invention is not limited thereto and may be a liquid or a low-pressure gas, or may be a mist mixture of liquid and gas.

[0123] Furthermore, in the aforementioned embodiments 1 to 7, the case where the fluid on the leakage space side is the atmosphere as a low-pressure gas is described, but it is not limited to this. As long as it is at a lower pressure than the sealed fluid, it can also be a liquid or a high-pressure gas, or it can be a mist mixed with liquid and gas.

[0124] Furthermore, in the above-described embodiments 1 to 7, the sealed fluid space side is described as the high-pressure side and the leakage space side as the low-pressure side. However, the sealed fluid space side and the leakage space side may be at substantially the same pressure.

[0125] Furthermore, in the above-mentioned embodiments 1 to 7, the barrier fluid is supplied from the stationary seal ring to the sliding surfaces. However, the barrier fluid may also be supplied from the rotating seal ring. Furthermore, the supply hole and the introduction groove may be formed in the same seal ring.

[0126] Furthermore, while the aforementioned embodiments 1 to 7 illustrate the provision of an inlet groove and a bypass groove on the rotating seal ring, both the inlet groove and the bypass groove may also be provided on the stationary seal ring. Alternatively, one of the inlet groove and the bypass groove may be provided on the rotating seal ring while the other may be provided on the stationary seal ring. Furthermore, the branch grooves may be provided on either the stationary seal ring or the rotating seal ring. Furthermore, the branch grooves, which serve as dynamic pressure generating portions, may have a spiral shape, in addition to Rayleigh steps.

[0127] Furthermore, in the above-mentioned embodiments 1 to 7, the bypass groove is exemplified as having both ends formed by inclined portions. However, for example, both ends of the bypass groove may extend radially from both ends of the peripheral portion and form a substantially right angle with the peripheral portion.

[0128] Label Description

[0129] 9: Static pressure gas supply source; 10: Stationary sealing ring (sealing ring on the other side); 11: Sliding surface; 20: Rotating sealing ring (sealing ring on one side); 21: Sliding surface; 23: Inlet groove; 25: Bypass groove; 224, 224': Outer diameter side dynamic pressure generating mechanism (branch groove); A: Atmosphere; F: Sealed fluid; G: Static pressure gas (isolating fluid); S1: External space (space on the sealed fluid side); S2: Internal space (space on the leakage side).

Claims

1. A mechanical seal disposed between a housing and a rotating shaft that rotates relative to the housing, wherein a stationary seal ring fixed to the housing and a rotating seal ring fixed to the rotating shaft rotate relative to each other, the mechanical seal partitioning a sealed fluid space from a leakage space, wherein a supply hole for supplying an isolation fluid between the sliding surfaces is formed on the sliding surface of at least one of the pair of seal rings, and an introduction groove is formed on the sliding surface of at least one of the pair of sliding rings, overlapping the supply hole in the axial direction and extending in the circumferential direction. in, A bypass groove is formed at a position closer to the leakage side than the introduction groove, with both ends in the circumferential direction extending toward the introduction groove.

2. The mechanical seal according to claim 1, wherein: The bypass groove has inclined portions at both ends in the circumferential direction. The inclined portion located on the upstream side in the relative rotation direction is inclined toward the upstream side of the introduction groove in the relative rotation direction, and the inclined portion located on the downstream side in the relative rotation direction is inclined toward the downstream side of the introduction groove in the relative rotation direction.

3. The mechanical seal according to claim 2, wherein: A peripheral edge portion extending in the circumferential direction is provided between the upstream inclined portion and the downstream inclined portion in the circumferential direction.

4. The mechanical seal according to any one of claims 1 to 3, wherein: Both ends of the bypass groove are communicated with the introduction groove.

5. The mechanical seal according to claim 1, wherein: A branch groove extends from the introduction groove toward the sealed fluid side.

6. The mechanical seal according to claim 5, wherein: The branch groove has a dynamic pressure generating portion extending in a relative rotation direction of the pair of seal rings.

7. The mechanical seal according to claim 5, wherein: The branch groove is arranged between both ends of the bypass groove in the circumferential direction.

8. The mechanical seal according to claim 1, wherein: The introduction groove is in an endless ring shape.

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