Mechanical seal

Abstract

Provided is a sliding member that is less likely to leak a sealing fluid and that enables sliding surfaces to be separated from each other evenly. A supply hole (10b) that supplies a barrier fluid (G) between the sliding surfaces (11, 21) is formed in the sliding surface (11) of at least one of a 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) in which both ends (252, 253) in the circumferential direction extend toward the introduction groove (23) is formed at a position on the leakage side (S2) from the introduction groove (23).

Description

Technical Field

[0001] This invention relates to sliding components that rotate relative to each other, such as mechanical seals used in shaft sealing devices for sealing rotating shafts of rotating machinery in the fields of automobiles, general industrial machinery, or other sealing applications. Background Technology

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

[0003] For example, the mechanical seal shown in Patent Document 1 has a fluid supply passage formed on the fixed sealing ring that connects the sealing surface to a fluid supply source located externally. Furthermore, the rotating sealing ring is provided with: a fluid guide groove extending circumferentially, through 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 to the high-pressure side; and a plurality of dynamic pressure generating grooves extending from the fluid guide groove to the low-pressure side.

[0004] When gas is supplied from a fluid supply source, the gas flows into the fluid guide channel and, through the dynamic pressure generating channels on the high-pressure and low-pressure sides, is evenly distributed as static pressure in the circumferential and radial directions between the opposing sliding surfaces, enabling the sliding surfaces to separate from each other using this static pressure. Furthermore, during relative rotation, in addition to the aforementioned static pressure, dynamic pressure is also generated in each dynamic pressure generating channel, thus further separating the sliding surfaces from each other and effectively reducing friction generated during relative rotation.

[0005] Existing technical documents

[0006] Patent documents

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

[0008] The problem that the invention aims to solve

[0009] In the mechanical seal described in Patent Document 1, although the hydrostatic and dynamic pressures generated by the pressure-generating grooves on the high-pressure and low-pressure sides can be approximately equal in the circumferential and radial directions between the sliding surfaces, thus achieving balanced separation of the sliding surfaces, the structure allows gas to easily leak from the hydrostatic grooves on the low-pressure side to the low-pressure side. Therefore, it is possible that the sealed fluid on the high-pressure side, along with the gas leaking from the hydrostatic grooves on the low-pressure side into the space between the sliding surfaces, could leak into the space on the low-pressure side.

[0010] The present invention was made in view of the problem that the object is to provide a sliding component with minimal leakage of the sealed fluid and capable of evenly separating the sliding surfaces from each other.

[0011] Methods for solving problems

[0012] To address the aforementioned issues, the mechanical seal of the present invention is disposed 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. This mechanical seal separates the sealed fluid space from the leakage space. Furthermore, a supply hole for providing isolation fluid between the sliding surfaces is formed on the sliding surface of at least one of the pair of sealing rings. An inlet groove that overlaps axially with the supply hole and extends circumferentially is formed on the sliding surface of at least one of the pair of sliding rings. A bypass groove extending circumferentially toward the inlet groove is formed at a position closer to the leakage side than the inlet groove.

[0013] Therefore, by using a bypass channel extending from the leakage side toward the inlet channel to recover fluid that is closer to the leakage side than the inlet channel, the leakage of the sealed fluid is reduced and the sliding surfaces can be evenly separated from each other.

[0014] Alternatively, the bypass groove may have inclined portions at both ends in the circumferential direction. The inclined portion located on the upstream side in the relative rotation direction is inclined towards 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 towards the downstream side of the inlet groove in the relative rotation direction.

[0015] Therefore, it is easy to introduce isolation fluid between the bypass channel and the inlet channel. Furthermore, a positive pressure is generated at the leak side end of the inclined section on the upstream side and a negative pressure is generated at the inclined section on the downstream side, so the leak side also floats evenly and the fluid flowing to the leak side is easily recovered.

[0016] Alternatively, a circumferentially extending peripheral portion may be provided between the inclined portion on the upstream side and the inclined portion on the downstream side.

[0017] Therefore, the circumferentially extending periphery becomes the negative pressure generating part, making it easier to recover fluid flowing out to a position closer to the leakage side than the inlet groove when a pair of sliding rings rotate relative to each other.

[0018] Alternatively, the two ends of the bypass groove can be connected to the inlet groove.

[0019] Therefore, when the pair of sliding rings are rotating relative to each other or when they are stationary, the isolation fluid can be introduced from the inlet groove to the bypass groove to separate the sliding surfaces.

[0020] Alternatively, a branch groove may extend from the inlet groove toward the sealed fluid side.

[0021] This allows for the balanced generation of pressure in the radial direction, stably separating the sliding surfaces from each other.

[0022] Alternatively, the branch groove may have a dynamic pressure generating portion extending along the relative rotational direction of the pair of sealing rings.

[0023] Therefore, in addition to the static pressure of the isolating fluid, the dynamic pressure generated during relative rotation also increases the buoyancy between the sliding surfaces. Furthermore, a large amount of isolating fluid can be discharged towards the sealed fluid side, thus suppressing leakage of the sealed fluid into the leakage space.

[0024] Alternatively, the branch groove may be disposed between the two ends of the bypass groove in the circumferential direction.

[0025] Therefore, by setting the bypass groove and the branch groove at the overlapping position in the radial direction, the sliding surfaces can be separated from each other more stably.

[0026] Alternatively, the inlet groove can be an endless ring.

[0027] This allows for the even generation of pressure in the circumferential direction, stably separating the sliding surfaces. Furthermore, during rotation, it prevents the generation of localized dynamic pressure in the circumferential direction of the guide groove. Attached Figure Description

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

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

[0030] Figure 3 yes Figure 2 A magnified view of a portion of the image.

[0031] Figure 4 (a) is a 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 shape of the hydrostatic pressure acting on the sliding surface of Example 1. Figure 5 (b) is a schematic diagram showing the shape of the dynamic pressure acting on the sliding surface in the same way.

[0033] Figure 6 This is a diagram showing the sliding surface of the rotary sealing ring of Embodiment 2 of the present invention viewed from the axial direction.

[0034] Figure 7 yes Figure 6 A magnified view of a portion of the image.

[0035] Figure 8 (a) is a 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 shape of the hydrostatic pressure acting on the sliding surface of Example 2. Figure 9 (b) is a schematic diagram showing the shape of the dynamic pressure acting on the sliding surface in the same way.

[0037] Figure 10 This is a diagram showing the inlet groove and branch groove of Embodiment 3 of the present invention viewed from the axial direction.

[0038] Figure 11 This is a diagram showing the inlet groove and branch groove of Embodiment 4 of the present invention viewed from the axial direction.

[0039] Figure 12 This is a diagram showing the inlet groove and branch groove of Embodiment 5 of the present invention viewed from the axial direction.

[0040] Figure 13 This is a diagram showing the inlet groove and branch groove of Embodiment 6 of the present invention viewed from the axial direction.

[0041] Figure 14 This is a diagram showing the inlet groove and branch groove of Embodiment 7 of the present invention viewed from the axial direction. Detailed Implementation

[0042] Hereinafter, the manner in which the mechanical seal is used to implement the present invention will be described based on embodiments.

[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 inner-side mechanical seal used to seal the fluid F that is to be leaked from the outer diameter side of the sliding surface toward the inner diameter side.

[0046] In detail, the sealed fluid F exists in the outer space S1 of the mechanical seal, and the atmosphere A exists in the inner space S2. In this embodiment, the outer diameter side of the sliding component 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 and other markings formed on the sliding surface are sometimes indicated in the accompanying drawings.

[0047] The mechanical seal mainly consists of a rotating sealing ring 20, which is a circular sliding ring, and a stationary sealing ring 10, which is also a circular sliding ring. The rotating sealing ring 20 is mounted on the rotating shaft 1 so as to be able to rotate together with the rotating shaft 1 via the sleeve 2. The stationary sealing ring 10 is mounted on the inner diameter side of the housing 4 of the installed equipment in a non-rotating state and a state that allows it to move axially.

[0048] Two O-rings 5 ​​are axially separated between the housing 4 and the stationary sealing ring 10. The housing 4 has a radially penetrating through hole 4a. The inner diameter opening of the through hole 4a communicates with the space 6 defined by the housing 4, the stationary sealing ring 10, and the two O-rings 5, and the outer diameter opening of the through hole 4a communicates with a static pressure gas supply source 9 located externally. Furthermore, a cover 8 is fixed to the housing 4, which is located on the side of the stationary sealing ring 10 opposite to the rotating sealing ring 20.

[0049] An elastic member 7 is disposed between the cover 8 and the stationary sealing ring 10. The stationary sealing ring 10 is subjected to axial force by the elastic member 7, and the sliding surface 11 of the stationary sealing ring 10 slides in close contact with the sliding surface 21 of the rotating sealing ring 20.

[0050] Furthermore, the stationary sealing ring 10 has multiple passages 10a extending from its outer peripheral surface to the sliding surface 11 in the circumferential direction. One end of each passage 10a communicates with the space 6, and the other end, the supply hole 10b, communicates with the guide groove 23 of the rotary sealing ring 20 (described later). Additionally, the sliding surface 11 of the stationary sealing ring 10, except for the supply hole 10b, is a flat surface.

[0051] The stationary sealing ring 10 and the rotary sealing 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 material suitable for use as a sliding material in a mechanical seal can be used. Furthermore, SiC can be represented by sintered bodies containing boron, aluminum, carbon, etc., as sintering aids, and can be composed of two or more phases with different compositions. Examples include SiC with dispersed graphite particles, reaction-sintered SiC composed of SiC and Si, SiC-TiC, SiC-TiN, etc. As for carbon, resin-molded carbon and sintered carbon, represented by carbonaceous and graphitic carbon, can be used. In addition to the above-mentioned sliding materials, metallic materials, resin materials, surface-modified materials (coating materials), composite materials, etc., can also be used.

[0052] like Figure 2 and Figure 3 As shown, the rotating sealing ring 20 can slide clockwise and counterclockwise relative to the stationary sealing ring 10, which serves as the opposite sealing ring. Figure 2 and Figure 3 The solid and dashed arrows indicate the relative rotation direction of the stationary sealing ring 10 with respect to the rotating sealing ring 20. Hereinafter, it will sometimes also be... Figure 2 and Figure 3 The direction of a solid line arrow is called the forward direction, and the direction of a dashed line arrow is called the reverse direction.

[0053] An inlet groove 23 and multiple bypass grooves 25 are provided on the sliding surface 21 of the rotary sealing ring 20. Furthermore, the portion other than the inlet groove 23 and bypass grooves 25 is a flat land area 22. Additionally, the portion of the inner diameter of the rotary sealing ring 20 for fitting the sleeve 2 is omitted from the illustration.

[0054] The inlet groove 23 and the rotary sealing ring 20 are arranged in a concentric circle. That is, the inlet groove 23 is an endless annular shape.

[0055] On the inner diameter side of the inlet groove 23, bypass grooves 25 are evenly arranged circumferentially (e.g., 8 in this embodiment).

[0056] The bypass groove 25 is roughly U-shaped when viewed along the axial direction. Specifically, the bypass groove 25 is composed of a peripheral portion 251 and inclined portions 252 and 253. Furthermore, the overall shape of the bypass groove 25 is such that its circumferential length is longer than its radial length.

[0057] The peripheral portion 251 extends circumferentially at a position further inward than the guide groove 23. This peripheral portion 251 is substantially parallel to the guide groove 23.

[0058] Inclined portions 252 and 253 extend from both ends of the peripheral portion 251 toward the guide groove 23 in mutually separating directions. Inclined portions 252 and 253 communicate with the guide groove 23. More specifically, inclined portion 252 is located on the upstream side in the forward rotation direction. Inclined portion 252 has a pair of circumferential walls. These walls extend in a straight line radially from the peripheral portion 251 toward the guide groove 23 and circumferentially from the peripheral portion 251 toward the upstream side in the forward rotation direction. That is, inclined portion 252 extends in a straight line obliquely from the peripheral portion 251 toward the guide groove 23 toward the upstream side in the forward rotation direction. Inclined portion 253 is located on the downstream side in the forward rotation direction. Inclined portion 253 has a pair of circumferential walls. These walls extend in a straight line radially from the peripheral portion 251 toward the guide groove 23 and circumferentially from the peripheral portion 251 toward the downstream side in the forward rotation direction. That is, the inclined portion 253 extends in a straight line from the peripheral portion 251 toward the downstream side of the guide groove 23 in the forward rotation direction. Furthermore, during reverse rotation, the upstream and downstream sides of the inclined portions 252 and 253 become opposite, but even in this case, the inclination direction remains the same. That is, the inclined portion on the upstream side inclines towards the upstream side, and the inclined portion on the downstream side inclines towards the downstream side. Additionally, the pair of circumferential walls constituting the inclined portion 252 and the pair of circumferential walls constituting the inclined portion 253 can also be shapes other than straight lines; for example, they can be curved, bent, or zigzag.

[0059] The bypass groove 25 is symmetrical in shape with reference to a line α that passes through the circumferential center of the peripheral portion 251 and extends radially. Furthermore, in the following description, the radially extending line α will be simply referred to as the radial line α.

[0060] like Figure 4 As shown in (a), the depth D1 of the guide 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 (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 pressures acting on the sliding surface 11 of the stationary sealing ring 10 and the sliding surface 21 of the rotating sealing ring 20 will be explained.

[0063] When static pressure gas G, acting as an isolation fluid, is supplied from static pressure gas supply source 9, the static pressure gas G is introduced into the inlet groove 23 of rotary sealing ring 20 (see reference) through through hole 4a of housing 4, space 6, passage 10a of static sealing ring 10, and supply hole 10b. Figure 1 In addition, the static 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. Thus, the static pressure of the gas G acts on the sliding surfaces 11 and 21, causing them to separate axially. In this way, the static pressure of the gas G acts not only in the inlet groove 23 but also in the bypass grooves 25 that branch radially from the inlet groove 23, thereby enabling the sliding surfaces 11 and 21 to separate evenly from each other. Furthermore, the static pressure of the gas G can be used to suppress the movement of the sealed fluid F flowing between the sliding surfaces 11 and 21 towards the inner diameter side.

[0065] And, as Figure 5 As shown in (b), 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 the inclined portion 253 in sequence, and returns to the inlet groove 23.

[0066] The flow of static pressure gas G within the bypass channel 25 caused by shearing can recover the fluid on the inner diameter side of the inlet channel 23, thus preventing static pressure gas G from leaking into the inner space S2. Therefore, the sealed fluid F is less likely to leak into the inner space S2 along with the static pressure gas G.

[0067] Specifically, since the fluid in the inclined section 253 is introduced into the flow of static pressure gas G in the main inlet channel 23, a relative negative pressure is generated in the inclined section 253 and the peripheral section 251 of the bypass channel 25 located downstream. On the other hand, since the static pressure gas G in the inlet channel 23 flows into the inclined section 252 of the bypass channel 25 located upstream, the relative pressure is higher than that in the inclined section 253 and the peripheral section 251. As a result, the peripheral section 251, which generates a relative negative pressure in the bypass channel 25, recovers the fluid near it. In addition, although the peripheral section 251 and the inclined section 253 have a relative negative pressure compared with the inclined section 252, the static pressure of the static pressure gas G in the inlet channel 23 and the inclined section 252 plays a dominant role, so it has almost no effect on the force that separates the sliding surfaces 11 and 21 from each other.

[0068] Furthermore, the flow of static pressure gas G within the bypass trough 25 is relatively faster at the periphery 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, and the influence of the shear force is relatively smaller in the inclined portions 252 and 253 compared to the periphery 251. Also, the flow in the inclined portion 252 is hindered by the bend between the inclined portion 252 and the periphery 251. Additionally, the flow in the inclined portion 253 is hindered by the static pressure within the guide trough 23. Therefore, the flow in the inclined portions 252 and 253 is slower compared to the periphery 251.

[0069] Furthermore, the inclined portion 252 of the bypass channel 25 slopes in the reverse direction from the peripheral portion 251 toward the inlet channel 23, while the inclined portion 253 slopes in the forward direction from the peripheral portion 251 toward the inlet channel 23. Therefore, during forward rotation, it is easy to introduce static pressure gas G from the inlet channel 23 into the inclined portion 252, and easy to discharge static pressure gas G from the inclined portion 253 into the inlet channel 23. Moreover, dynamic pressure is generated at the leakage side end 252a of the inclined portion 252 on the upstream side of the forward rotation direction, that is, near the bending point of the inclined portion 252 and the peripheral portion 251, so that it can float evenly even on the leakage side.

[0070] Furthermore, the static pressure gas G returns from a position closer to the inner diameter of the inlet groove 23 towards the inlet groove 23, so the static pressure gas G is not easily leaked from the inner space S2.

[0071] Furthermore, since the inclined portions 252 and 253 are connected to the inlet groove 23, it is easy to introduce and export static pressure gas G between the inclined portions 252 and 253 and the inlet groove 23. Moreover, when the relative sliding of the sliding surfaces 11 and 21 stops, static pressure gas G can also be introduced from the inlet groove 23 to the bypass groove 25, thus enabling the sliding surfaces 11 and 21 to separate from each other.

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

[0073] Furthermore, the guide groove 23 is annular, thus generating pressure evenly in the circumferential direction, which can stably separate the sliding surfaces 11 and 21 from each other. Moreover, during relative rotation, it is not easy to generate local dynamic pressure in the circumferential direction of the guide groove 23.

[0074] Furthermore, the bypass groove 25 is symmetrical about the radial line α, so the fluid recovery capacity of the bypass groove 25 does not change with the rotation direction of the rotary sealing ring 20. Moreover, when reversing, dynamic pressure can be generated at the leakage end 253a of the inclined portion 253 on the upstream side of the reversing direction, that is, near the bending point of the inclined portion 253 and the peripheral portion 251.

[0075] Furthermore, in this embodiment, the depth D1 of the guide groove 23 is shown to be approximately twice the depth D2 of the inclined portion 253, but their depths can be freely varied. 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 depth of the bypass slot 25 is shown to be constant, but it can also be extended in different directions.

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

[0078] Furthermore, in this embodiment, the bypass groove 25 is shown to be symmetrical with respect to the radial line α, but it can also be asymmetrical with respect to the radial line.

[0079] Example 2

[0080] Next, refer to Figures 6-9 The mechanical seal of Example 2 will be described. Furthermore, repeated structural descriptions identical to those of Example 1 will be omitted.

[0081] like Figure 6 and Figure 7 As shown, in this embodiment 2, the sliding surface 221 of the rotary sealing ring 220 is provided with an inlet groove 223, a dynamic pressure generating mechanism 224, 224' serving as a branch groove on the outer diameter side, and a bypass groove 225. Furthermore, the inlet groove 223 and the bypass groove 225 have the same structure as those in embodiment 1.

[0082] On the outer diameter side of the inlet groove 223, groups of outer diameter side dynamic pressure generating mechanisms 224 and 224' are evenly arranged circumferentially (e.g., 8 groups in this embodiment). The outer diameter side dynamic pressure generating mechanisms 224 and 224' are arranged circumferentially between the inclined portions 225A and 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 the dynamic pressure generating part. The radial groove 224A extends from the guide groove 223 in the outer diameter direction. The circumferential groove 224B extends from the outer diameter end of the radial groove 224A in the forward rotation direction, approximately parallel to the guide groove 223.

[0084] Furthermore, the outer diameter side dynamic pressure generating mechanism 224' is arranged separately from the outer diameter side dynamic pressure generating mechanism 224 in the reverse direction. The outer diameter side dynamic pressure generating mechanism 224' is symmetrical to the outer diameter side dynamic pressure generating mechanism 224 with the radial line α as the reference.

[0085] like Figure 8 As shown in (a), the depth D10 of the inlet groove 223 is the same as 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 deeper than the depth D30 of the bypass groove 225 (D20 > D30). Specifically, the depth D30 is approximately half the depth D20. In addition, the depth D30 can be freely varied as long as it is shallower than the depth D20.

[0087] like Figure 8 As shown in (b), the bottom surface 224b of the circumferential groove 224B is an inclined surface that gradually becomes shallower from the bottom surface 224a 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 dynamic pressure generating mechanisms 224, 224' on the outer diameter side and the bypass grooves 225. Thus, the static pressure of the static pressure gas G acts on the sliding surface 11 and the sliding surface 21, causing them to separate axially. In this way, the static pressure of the static pressure gas G acts not only in the inlet groove 223 but also in the portions of the dynamic pressure generating mechanisms 224, 224' and the bypass grooves 225 that branch radially from the inlet groove 23, thereby enabling the sliding surfaces 11 and 21 to separate evenly from each other.

[0089] And, as Figure 9 As shown in (b), 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 223, the outer diameter side dynamic pressure generating mechanisms 224 and 224', and the bypass groove 225 moves in the forward direction. As a result, dynamic pressure is generated near the end 224c of the circumferential groove 224B and near the leakage side end 225a of the inclined portion 225A upstream in the forward direction of the bypass groove 225, i.e., near the intersection of the inclined portion 225A and the circumferential portion 225C, and the fluid around the bypass groove 225 can be recovered. That is, on the sliding surfaces 11 and 21, in addition to the static pressure of the static pressure gas G, dynamic pressure also acts on the sides closer to the sealed fluid side and the leakage side than inlet groove 223, thus enabling further separation of the sliding surfaces 11 and 21.

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

[0091] Furthermore, the outer diameter-side dynamic pressure generating mechanisms 224 and 224' are disposed between the inclined portions 225A and 225B at both ends of the bypass groove 225. In other words, the outer diameter-side dynamic pressure generating mechanisms 224 and 224' and the bypass groove 225 are positioned at a radially overlapping location. As a result, pressure can be generated at the radially overlapping location, thus enabling the sliding surfaces 11 and 21 to separate from each other more stably.

[0092] Furthermore, dynamic pressure can be generated on the outer diameter side dynamic pressure generating mechanism 224 during forward rotation, and on the reverse side, dynamic pressure can be generated near the leakage side end 225b of the inclined portion 225B on the upstream side of the reverse side of the outer diameter side dynamic pressure generating mechanism 224' and the bypass groove 225, i.e., near the intersection of the inclined portion 225B and the peripheral portion 225C. That is, dynamic pressure can be generated regardless of the rotation direction of the rotary sealing ring 220.

[0093] In addition, in this embodiment 2, an outer diameter side dynamic pressure generating mechanism 224, 224' is arranged between the inclined portions 225A, 225B at both ends of the bypass groove 225, but the branch groove can also be arranged to be offset from the bypass groove in the circumferential direction.

[0094] Furthermore, in this embodiment 2, the outer diameter side dynamic pressure generating mechanisms 224, 224' are illustrated as being composed of radial grooves 224A and circumferential grooves 224B. However, for example, spiral grooves having both circumferential and radial components may also be used. Additionally, the branch grooves may be composed solely of radial grooves.

[0095] Example 3

[0096] Next, refer to Figure 10 The mechanical seal of Example 3 will be described. Furthermore, repeated structural descriptions identical to those of Example 2 described above will be omitted.

[0097] like Figure 10 As shown, in the rotary sealing ring 320 of this embodiment 3, the inclined portions 325A and 325B at both ends of the radial grooves 324A and 324A' and the bypass groove 325 of the outer diameter side dynamic pressure generating mechanisms 324 and 324' are not connected to the guide groove 323. In addition, the outer diameter side dynamic pressure generating mechanisms 324 and 324' of this embodiment are formed to a constant depth.

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

[0099] Similarly, the radial width L41 of the land portion 322b between the inclined portions 325A, 325B and the guide groove 323 is shorter than the radial width L50 of the guide groove 323 (L41 < L50). In addition, the radial width L41 only needs to be shorter than the radial width L50, preferably less than 1 / 5.

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

[0101] Thus, in the mechanical seal of the present invention, regarding the branch groove and bypass groove 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 groove and bypass groove, it is also possible, as in this embodiment, that the branch groove and bypass groove are not connected to the inlet groove.

[0102] Example 4

[0103] Next, refer to Figure 11 The mechanical seal of Example 4 will be described. Furthermore, repeated structural descriptions identical to those of Example 2 described above will be omitted.

[0104] like Figure 11 As shown, the bypass groove 425 of the rotary sealing ring 420 in this embodiment 4 is V-shaped when viewed along the axial direction.

[0105] Specifically, in the bypass groove 425, inclined portions 425A and 425B extend from the top 425C, which is located approximately at the center of the circumferential direction, toward the guide groove 423 in mutually separated directions. That is, the bypass groove 425 of this embodiment 4 does not have the peripheral portion 251 of embodiment 1.

[0106] Thus, the mechanical seal of the present invention only needs to allow the isolation fluid to move between the inlet 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 The mechanical seal of Example 5 will be described. Furthermore, repeated structural descriptions identical to those of Example 2 described above will be omitted.

[0109] like Figure 12As shown, the rotary sealing ring 520 of this embodiment 5 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 embodiment 2.

[0110] Thus, the mechanical seal of the present invention can also handle forward rotation.

[0111] Example 6

[0112] Next, refer to Figure 13 The mechanical seal of Example 6 will be described. Furthermore, repeated structural descriptions identical to those of Example 2 described above will be omitted.

[0113] like Figure 13 As shown, in the rotary sealing ring 620 of this embodiment 6, the guide groove 623 is broken at point 1 in the circumferential direction. Thus, the guide groove 623 is not limited to an annular groove, but can also be approximately C-shaped.

[0114] In addition, the inlet groove is not limited to a C-shape; it can also be divided into multiple sections in the circumferential direction, or it can be a ring-shaped waveform or a ring-shaped polygon.

[0115] Example 7

[0116] Next, refer to Figure 14 The mechanical seal of Example 7 will be described. Furthermore, repeated structural descriptions identical to those of Example 2 described above will be omitted.

[0117] The mechanical seal of the rotary sealing ring 720 in this embodiment 7 is an external mechanical seal that communicates with the outer space S1 of the sliding surface 721 and seals the fluid F to be sealed on the inner space S2 side.

[0118] In this embodiment 7, the dynamic pressure generating mechanisms 724 and 724' are arranged on the inner diameter side of the guide groove 723, and the bypass groove 725 is arranged on the outer diameter side of the guide groove 723.

[0119] Thus, the mechanical seal of the present invention can also be applied to environments where the sealed fluid space is closer to the inner diameter side than the sliding surface and the leakage space is closer to the outer diameter side than the sliding surface.

[0120] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments, and changes and additions that do not depart from the spirit of the present invention are also included in the present invention.

[0121] For example, in the aforementioned embodiments 1 to 7, mechanical seals for industrial machinery were used as an example, but other mechanical seals, such as those for automobiles, could also be used.

[0122] Furthermore, in the aforementioned Examples 1 to 7, the case where the sealed fluid is a high-pressure gas was described, but it is not limited to this. It may also be a liquid or a low-pressure gas, or a mist containing a mixture of liquid and gas.

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

[0124] Furthermore, in the aforementioned embodiments 1 to 7, the sealed fluid space side was described as the high-pressure side and the leakage space side as the low-pressure side, but the sealed fluid space side and the leakage space side may also have approximately the same pressure.

[0125] Furthermore, in the aforementioned embodiments 1 to 7, a method of providing isolation fluid from the stationary sealing ring side to the sliding surface was illustrated, but isolation fluid can also be provided from the rotating sealing ring side to the sliding surface. Additionally, the supply hole and the inlet groove can also be formed on the same sealing ring.

[0126] Furthermore, in the aforementioned embodiments 1 to 7, an example was shown where a guide groove and a bypass groove were provided on the rotary sealing ring. However, the guide groove and bypass groove can also be provided on the stationary sealing ring, or one of the guide groove and bypass groove can be provided on the rotary sealing ring, and the other of the guide groove and bypass groove can be provided on the stationary sealing ring. Additionally, the branch groove can be provided on either the stationary sealing ring or the rotary sealing ring. Furthermore, the branch groove having a dynamic pressure generating portion can be, in addition to a Rayleigh step, a spiral shape, etc.

[0127] Furthermore, in the aforementioned embodiments 1 to 7, the bypass groove is illustrated in a manner in which both ends are composed of inclined portions. However, for example, the two ends of the bypass groove may extend radially from both ends of the peripheral portion, forming approximately right angles with the peripheral portion.

[0128] Label Explanation

[0129] 9: Static pressure gas supply source; 10: Static sealing ring (the other party's sealing ring); 11: Sliding surface; 20: Rotating sealing ring (one party's sealing ring); 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 (isolation fluid); S1: Outer space (sealed fluid side space); S2: Inner space (leakage side space).

Claims

1. A mechanical seal disposed between a housing and a rotating shaft that rotates relative to the housing, wherein 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 separating a sealing fluid space from a leakage space, and wherein a supply orifice for providing isolation fluid between the sliding surfaces is formed on the sliding surface of at least one of the stationary sealing ring and the rotating sealing ring, and an inlet groove that overlaps axially with the supply orifice and extends circumferentially is formed on the sliding surface of at least one of the stationary sealing ring and the rotating sealing ring. in, A bypass groove is formed at a position closer to the leakage side than the inlet groove, with both ends extending circumferentially toward the inlet groove. 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 towards 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 towards the downstream side of the inlet groove in the relative rotation direction.

2. The mechanical seal according to claim 1, wherein, A circumferentially extending circumferential portion is provided between the inclined portion on the upstream side and the inclined portion on the downstream side.

3. The mechanical seal according to claim 1 or 2, wherein, The two ends of the bypass groove are connected to the inlet groove.

4. The mechanical seal according to claim 1, wherein, The inlet groove is an endless ring.

5. A mechanical seal disposed between a housing and a rotating shaft that rotates relative to the housing, wherein 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 separating a sealing fluid space from a leakage space, and wherein a supply orifice for providing isolation fluid between the sliding surfaces is formed on the sliding surface of at least one of the stationary sealing ring and the rotating sealing ring, and an inlet groove that overlaps axially with the supply orifice and extends circumferentially is formed on the sliding surface of at least one of the stationary sealing ring and the rotating sealing ring. in, A bypass groove is formed at a position closer to the leakage side than the inlet groove, with both ends extending circumferentially toward the inlet groove. A branch groove extends from the inlet 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 along the relative rotational direction of the stationary sealing ring and the rotating sealing ring.

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

8. The mechanical seal according to claim 5, wherein, The inlet groove is an endless ring.

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