Mechanical seal

Abstract

To inexpensively form a recessed part on a seal surface of a mechanical seal.SOLUTION: A mechanical seal includes: a rotary seal ring provided on a rotary shaft side in an integrally rotatable manner and having a seal surface; a stationary seal ring provided on a casing side encircling the rotary shaft and having a seal surface opposed to the seal surface of the rotary seal ring; and an elastic member for thrusting one of the rotary seal ring and the stationary seal ring to the other side. The mechanical seal further includes: a first abutment part on which a part of an end face on the opposite side to the seal surface of at least one seal ring out of the rotary seal ring and the stationary seal ring abuts; and a second abutment part on which the other part of the end face of the one seal ring abuts. Between the first abutment part and the second abutment part, a space is formed to allow deformation to the opposite side of the one seal ring.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a mechanical seal. [Background technology]

[0002] The mechanical seal described in Patent Document 1 includes a stationary seal ring (fixed ring) provided on the housing side, a rotating seal ring (rotary ring) provided on the rotating shaft side and sliding against the stationary seal ring, and an elastic member (bellows) that presses the stationary seal ring against the rotating seal ring. The stationary seal ring and the rotating seal ring have seal surfaces (sliding surfaces) that slide against each other while being in close contact with each other due to the biasing force of the elastic member. One of these seal surfaces has a plurality of recesses (accommodating blocks) formed in the circumferential direction. The sealed fluid enters the recesses to form a lubricating film between the two seal surfaces, ensuring the lubrication of both seal surfaces. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-028210 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above mechanical seal, the stationary seal ring and the rotating seal ring are made of silicon carbide (SiC), a hard material with excellent wear resistance, so it is difficult to cut recesses in the seal surface using a general-purpose machine tool. Therefore, in order to form recesses in the seal surface, a special processing method must be used, which increases the manufacturing cost.

[0005] An object of the present disclosure is to enable formation of recesses in the sealing surface of a mechanical seal at low cost. [Means for solving the problem]

[0006] (1) The present disclosure relates to a mechanical seal comprising: a rotary seal ring provided on a rotating shaft side so as to be rotatable integrally with the rotating shaft and having a seal surface; a stationary seal ring provided on a casing side surrounding the rotating shaft and having a seal surface facing the seal surface of the rotary seal ring; and an elastic member pressing one of the rotary seal ring and the stationary seal ring toward the other side, wherein the mechanical seal seals a sealed fluid within an in-machine area using the rotary seal ring and the stationary seal ring, the mechanical seal comprising: a first abutment portion with which a part of an end face opposite to the seal surface of at least one of the rotary seal ring and the stationary seal ring abuts; and a second abutment portion with which another part of the end face of the one seal ring abuts, and between the first abutment portion and the second abutment portion a space is formed to allow deformation of the one seal ring toward the opposite side.

[0007] According to the mechanical seal of the present disclosure, the end face of the one seal ring opposite the seal surface is strongly pressed against the first and second abutment portions by the elastic force of the elastic member and the pressure of the sealed fluid. As a result, a portion of the one seal ring is deformed toward the opposite side so as to protrude toward the space formed between the two abutment portions. Due to this deformation, an area of ​​the seal surface of the one seal ring corresponding to the portion is recessed toward the opposite side, so that a recess is formed within that area. Therefore, by utilizing the elastic force of the elastic member and the pressure of the sealed fluid, a recess is formed on the seal surface of the mechanical seal, so that the recess can be formed at low cost.

[0008] (2) The mechanical seal of (1) above preferably includes a pressing member disposed on the opposite side of the one seal ring, and the pressing member preferably has the first contact portion and the second contact portion. In this case, since the first contact portion and the second contact portion are unitized into the pressing member, the mechanical seal can be easily assembled.

[0009] (3) In the mechanical seal of (2) above, it is preferable that the pressing member is formed in an annular shape concentric with one of the seal rings. In this case, since the first contact portion and the second contact portion can be disposed at any circumferential position on the annular pressing member, a recess can be formed at any circumferential position on the seal surface of the one seal ring.

[0010] (4) In the mechanical seal of any one of (1) to (3) above, the one seal ring is preferably made of a hard material. In this case, the recess can be formed at low cost even in the seal surface of the one seal ring made of a hard material which is difficult to machine. Effect of the Invention

[0011] According to the present disclosure, recesses can be formed in the sealing surface of a mechanical seal at low cost. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of a mechanical seal according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view showing a pressing member and a stationary seal ring of the first embodiment. [Diagram 3] FIG. 6 is a cross-sectional view of a mechanical seal according to a second embodiment. [Figure 4] FIG. 11 is a perspective view showing a pressing member and a rotary seal ring of a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that at least some of the embodiments described below may be combined in any combination. [First embodiment] <Overall composition> Fig. 1 is a cross-sectional view of a mechanical seal 1 according to a first embodiment. In Fig. 1, the mechanical seal 1 is used in a rotating device 70 such as a pump, and seals a sealed fluid inside the rotating device 70. The mechanical seal 1 is disposed between a rotating shaft 71 of the rotating device 70 and a casing 72 surrounding the rotating shaft 71, along the axial direction of the rotating shaft 71.

[0014] Hereinafter, in this specification, the "axial direction" refers to the direction along the axis X of the rotating shaft 71. In addition, in this specification, the "radial direction" refers to the direction perpendicular to the axis X of the rotating shaft 71, and the "circumferential direction" refers to the direction around the axis X of the rotating shaft 71. In addition, in this specification, for convenience, the right side in Fig. 1 is referred to as one axial side, and the left side in Fig. 1 is referred to as the other axial side (the same applies to Fig. 3).

[0015] The mechanical seal 1 of this embodiment is a so-called rotary type mechanical seal. The mechanical seal 1 includes a rotary unit 2 provided on a rotary shaft 71 so as to be integrally rotatable therewith, and a stationary unit 3 provided on a casing 72.

[0016] <Rotating unit> The rotating unit 2 includes a first retainer 11, a set screw 12, a drive collar 13, a spring (elastic member) 14, a second retainer 15, and a rotary seal ring 16. The first retainer 11 is formed in an annular shape and is fitted onto the outer peripheral surface of one axial side of the rotating shaft 71. A plurality of set screws 12 (only one is shown in FIG. 1 ) arranged in the circumferential direction are radially fastened into the first retainer 11. As a result, the first retainer 11 is fixed to the rotating shaft 71.

[0017] The drive collar 13 is disposed on the other axial side of the first retainer 11 with a gap therebetween. The drive collar 13 is formed in an annular shape, and is fitted to the outer circumferential surface of the rotating shaft 71 so as to be movable in the axial direction. The drive collar 13 is held to be movable in the axial direction with respect to the first retainer 11 via a drive pin (not shown), and its relative rotation with respect to the first retainer 11 is restricted.

[0018] A plurality of springs 14 (only one is shown in FIG. 1) are provided at intervals in the circumferential direction between the first retainer 11 and the drive collar 13. The springs 14 are, for example, compression coil springs. The springs 14 press the drive collar 13 toward the other axial side relative to the first retainer 11 by their elastic force.

[0019] The second retainer 15 is disposed adjacent to the other axial side of the drive collar 13. The second retainer 15 is formed in an annular shape and is fitted to the outer circumferential surface of the rotating shaft 71 so as to be movable in the axial direction. One axial end of the second retainer 15 is fixed to the drive collar 13. As a result, the second retainer 15 is held together with the drive collar 13 so as to be movable in the axial direction relative to the rotating shaft 71, and relative rotation with respect to the drive collar 13 is restricted. An O-ring 17 provides a seal (secondary seal) between the inner circumferential surface of the second retainer 15 and the outer circumferential surface of the rotating shaft 71.

[0020] The rotary seal ring 16 is formed in an annular shape and is fixed to the other axial end of the second retainer 15. The rotary seal ring 16 is made of a hard material with excellent wear resistance, such as silicon carbide (SiC) or cemented carbide. A seal surface 16a is formed on the other axial end of the rotary seal ring 16. The seal surface 16a is a flat surface extending in the radial direction. The elastic force of the spring 14 presses the rotary seal ring 16 towards the other axial end via the drive collar 13 and the second retainer 15.

[0021] <Stationary unit> The stationary unit 3 includes a seal case 31, a pressing member 32, and a stationary seal ring 33. The seal case 31 is formed in a cylindrical shape. The seal case 31 surrounds a rotating shaft 71 and is fixed to a casing 72 in order to separate an in-machine area A and an out-machine area B of a rotating device 70. Specifically, one axial side of the seal case 31 is fixed to the casing 72 by a bolt 34 and a nut 35 in a state of abutting against a side of the casing 72 on the other axial side. A seal (secondary seal) is formed between the side of the seal case 31 on the one axial side and the side of the casing 72 on the other axial side by an O-ring 36.

[0022] A stepped surface 31a extending radially inward is formed on the inner peripheral side of the seal case 31. The stepped surface 31a faces one axial side (the rotating unit 2 side). A pressing member 32 is fitted and fixed to the inner peripheral surface of the seal case 31. The pressing member 32 is disposed adjacent to one axial side of the stepped surface 31a, and is also disposed adjacent to the other axial side of the stationary seal ring 33. Details of the pressing member 32 will be described later.

[0023] The stationary seal ring 33 is formed in an annular shape and is fitted and fixed to the inner peripheral surface of the seal case 31 on one axial side of the pressing member 32. The stationary seal ring 33 is made of a hard material with excellent wear resistance, such as SiC or cemented carbide, like the rotary seal ring 16. An O-ring 37 provides a seal (secondary seal) between the outer peripheral surface of the stationary seal ring 33 and the inner peripheral surface of the seal case 31.

[0024] A seal surface 33a facing the seal surface 16a of the rotary seal ring 16 is formed on one axial side of the stationary seal ring 33. This seal surface 33a is a flat surface extending in the radial direction. The seal surface 16a of the rotary seal ring 16, which is pressed to the other axial side by the spring 14, slides in close contact with the seal surface 33a of the stationary seal ring 33. As a result, an in-machine area A in which the sealed fluid is sealed is formed radially outward of both the seal surfaces 16a, 33a of the rotary seal ring 16 and the stationary seal ring 33. An end surface 33b parallel to the seal surface 33a is formed on the other axial side of the stationary seal ring 33 (opposite the seal surface 33a). The end surface 33b is formed flat over the entire radial direction.

[0025] <Pressing part> Fig. 2 is a perspective view showing the pressing member 32 and the stationary seal ring 33. For convenience, the pressing member 32 and the stationary seal ring 33 are shown separated from each other in the axial direction in Fig. 2. In Figs. 1 and 2, the pressing member 32 is a member against which the stationary seal ring 33 is pressed from one axial side.

[0026] The pressing member 32 is made of a plate member formed in an annular shape concentric with the stationary seal ring 33. The pressing member 32 is made of an easily machined material, such as stainless steel (SUS), aluminum, titanium, etc. A side surface 320 on the other axial side of the pressing member 32 is formed flat in the radial direction so that the entire side surface 320 is in surface contact with the stepped surface 31a of the seal case 31.

[0027] A plurality of grooves 322 recessed toward the other axial direction are formed at intervals (equally spaced in FIG. 2) in the circumferential direction on a side surface 321 on one axial side of the pressing member 32. These grooves 322 are formed by cutting the base material of the pressing member 32 with a general-purpose machine tool. Each groove 322 is formed across the entire radial width of the pressing member 32. Each groove 322 is formed in a substantially trapezoidal shape when viewed from one axial side. Each groove 322 is formed so that the circumferential groove width gradually increases from the radial inner end to the radial outer end of the pressing member 32.

[0028] The pressing member 32 has a plurality of contact portions 323 protruding to one axial side by forming a plurality of grooves 322. That is, the pressing member 32 has a plurality of contact portions 323 integrally formed at intervals in the circumferential direction on either side of the grooves 322. The plurality of contact portions 323 include a predetermined number of first contact portions 324 and a predetermined number of second contact portions 325.

[0029] The first contact portions 324 and the second contact portions 325 are the same in number and are arranged alternately in the circumferential direction of the pressing member 32. The pressing member 32 of this embodiment has eight contact portions 323, and four first contact portions 324 and four second contact portions 325 are arranged alternately in the circumferential direction of the pressing member 32.

[0030] The first contact portion 324 has a protruding end surface 324a which is a part of the side surface 321 of the pressing member 32. Similarly, the second contact portion 325 has a protruding end surface 325a which is another part of the side surface 321 of the pressing member 32.

[0031] An end face 33b of the stationary seal ring 33 pressed by the spring 14 abuts against the side surface 321 of the pressing member 32. A circumferential portion of the end face 33b of the stationary seal ring 33 abuts against a protruding end face 324a of the first abutment portion 324. Another circumferential portion of the end face 33b of the stationary seal ring 33 abuts against a protruding end face 325a of the second abutment portion 325 circumferentially adjacent to the first abutment portion 324.

[0032] A space S1 is formed in the recessed groove 322 between the first abutment portion 324 and the second abutment portion 325 that are adjacent in the circumferential direction. That is, the pressing member 32 has the same number of spaces S1 (here, eight) as the number of recessed grooves 322 formed at intervals in the circumferential direction. The spaces S1 allow a circumferential portion of the stationary seal ring 33 corresponding to the spaces S1 to deform so as to protrude toward the other axial side.

[0033] Since the pressure of the sealed fluid acts on the seal surface 33a of the stationary seal ring 33, the stationary seal ring 33 is pressed from the seal surface 33a toward the end face 33b in the other axial direction. When the stationary seal ring 33 is pressed toward the other axial direction by the elastic force of the spring 14 and the pressure of the sealed fluid, the end face 33b of the stationary seal ring 33 is pressed strongly against the protruding end faces 324a, 325a of the first abutment portion 324 and the second abutment portion 325 that are adjacent in the circumferential direction of the pressing member 32. Then, a portion of the stationary seal ring 33 corresponding to the space S1 is deformed so as to protrude toward the other axial direction within the space S1.

[0034] When the portion of the stationary seal ring 33 is deformed, an area C (indicated by a two-dot chain line in FIG. 2) in the seal surface 33a of the stationary seal ring 33 corresponding to the portion is slightly recessed toward the other axial side, and a recess 33c is formed in the area C. As a result, a plurality of recesses 33c (eight in FIG. 2) are formed in the circumferential direction in the seal surface 33a of the stationary seal ring 33. The axial depth of each recess 33c is several μm. Note that the stationary seal ring 33 in FIGS. 1 and 2 shows a state before deformation.

[0035] The sealed fluid in the in-machine area A enters each recess 33c formed in the seal surface 33a of the stationary seal ring 33. As a result, a lubricating film is formed by the sealed fluid between both the seal surfaces 16a, 33a of the rotating seal ring 16 and the stationary seal ring 33, ensuring lubrication of both the seal surfaces 16a, 33a.

[0036] <Action and effect> According to the mechanical seal 1 of this embodiment, the end face 33b on the other axial side of the stationary seal ring 33 is strongly pressed against the first abutment portion 324 and the second abutment portion 325 of the pressing member 32 by the elastic force of the spring 14 and the pressure of the sealed fluid. As a result, a circumferential portion of the stationary seal ring 33 is deformed so as to protrude toward the space S1 formed between the circumferentially adjacent abutment portions 324, 325. Due to this deformation, the region C corresponding to the portion on the seal surface 33a of the stationary seal ring 33 is recessed toward the other axial side, so that the recess 33c is formed in the region C. Therefore, by utilizing the elastic force of the spring 14 and the pressure of the sealed fluid, the recess 33c is formed on the seal surface 33a of the stationary seal ring 33, so that the recess 33c can be formed at low cost. In particular, when the stationary seal ring 33 is made of a hard material, it is difficult to machine a recess on the seal surface 33a of the stationary seal ring 33, so that the configuration of this embodiment is more effective.

[0037] The first contact portion 324 and the second contact portion 325 are formed as a unit integrally with the pressing member 32. Therefore, the first contact portion 324 and the second contact portion 325 can be attached to the casing 72 side simply by arranging the pressing member 32 on the inner periphery of the seal case 31. Therefore, the mechanical seal 1 can be easily assembled.

[0038] The pressing member 32 is formed in an annular shape concentric with the stationary seal ring 33. As a result, the first contact portion 324 and the second contact portion 325 can be formed at any circumferential position of the annular pressing member 32, and therefore the recess 33c can be formed at any circumferential position of the seal surface 33a of the stationary seal ring 33.

[0039] [Second embodiment] 3 is a cross-sectional view of a mechanical seal 1 according to a second embodiment. The mechanical seal 1 of this embodiment differs from the first embodiment in that it is a so-called stationary mechanical seal and that the shape of the groove in the pressing member is different. The mechanical seal 1 of this embodiment includes a rotating unit 2 provided on a rotating shaft 71 so as to be integrally rotatable therewith, and a stationary unit 3 provided on a casing 72, as in the first embodiment.

[0040] <Rotation unit> The rotating unit 2 includes a sleeve 21, a pressing member 22, and a rotating seal ring 23. The sleeve 21 has a cylindrical sleeve main body 21a fitted and fixed to the outer periphery of the rotating shaft 71, an annular portion 21b extending radially outward from one axial end of the sleeve main body 21a, and a cylindrical portion 21c extending from the radial outer end of the annular portion 21b to the other axial side.

[0041] A pressing member 22 is fitted and fixed to one axial side of the inner circumferential surface of the cylindrical portion 21c of the sleeve 21. The pressing member 22 is disposed adjacent to the other axial side of the annular portion 21b of the sleeve 21, and is also disposed adjacent to one axial side of the rotary seal ring 23. Details of the pressing member 22 will be described later.

[0042] The rotary seal ring 23 is formed in an annular shape and is fitted and fixed to the inner circumferential surface of the cylindrical portion 21c of the sleeve 21 on the other axial side of the pressing member 22. The rotary seal ring 23 is made of a hard material, similar to the rotary seal ring 16 of the first embodiment. A seal surface 23a is formed on the other axial side of the rotary seal ring 23. The seal surface 23a is a flat surface extending in the radial direction.

[0043] An end face 23b parallel to the seal face 23a is formed on one axial side of the rotary seal ring 23 (opposite the seal face 23a). The end face 23b is formed flat over the entire radial direction. An O-ring 24 provides a seal (secondary seal) between the inner peripheral surface of the cylindrical portion 21c and the outer peripheral surface of the rotary seal ring 23.

[0044] <Stationary unit> The stationary unit 3 includes a seal case 41, a retainer 42, a spring (elastic member) 43, and a stationary seal ring 44. One axial side of the seal case 41 is fixed to the casing 72 by a bolt 45 and a nut 46 in a state of contact with the other axial side of the casing 72. An O-ring 47 provides a seal (secondary seal) between the one axial side of the seal case 41 and the other axial side of the casing 72.

[0045] The seal case 41 has a wall portion 41a extending radially inward from the casing 72, and a cylindrical portion 41b extending from a radial inner end of the wall portion 41a to one side in the axial direction. The other configuration of the seal case 41 is similar to that of the seal case 31 of the first embodiment (except for the stepped surface 31a), and therefore description thereof will be omitted.

[0046] The retainer 42 is formed in an annular shape and is axially movably fitted to the outer circumferential surface of the cylindrical portion 41b of the seal case 41. An O-ring 48 provides a seal (secondary seal) between the inner circumferential surface of the retainer 42 and the outer circumferential surface of the cylindrical portion 41b.

[0047] A plurality of springs 43 (only one is shown in FIG. 3 ) are provided at intervals in the circumferential direction between the retainer 42 and the wall portion 41a of the seal case 41. The springs 43 are, for example, compression coil springs. The springs 43 press the retainer 42 toward one axial side relative to the seal case 41 by their elastic force.

[0048] The stationary seal ring 44 is formed in an annular shape and is fixed to one end of the retainer 42 in the axial direction. The stationary seal ring 44 is made of a hard material, similar to the stationary seal ring 33 of the first embodiment. A seal surface 44a that faces the seal surface 23a of the rotary seal ring 23 is formed on one axial side of the stationary seal ring 44. This seal surface 44a is a flat surface extending in the radial direction. The stationary seal ring 44 is pressed toward one axial side via the retainer 42 by the elastic force of the spring 43. As a result, the rotary seal ring 23 is pressed toward one axial side via the retainer 42 and the stationary seal ring 44 by the elastic force of the spring 43.

[0049] The seal surface 44a of the stationary seal ring 44 is pressed axially to one side by the spring 43, so that it is in close contact with the seal surface 23a of the rotary seal ring 23. The seal surface 23a of the rotary seal ring 23 slides in close contact with the seal surface 44a of the stationary seal ring 44. As a result, an in-machine area A in which the sealed fluid is sealed is formed radially outward of both the seal surfaces 23a, 44a of the rotary seal ring 23 and the stationary seal ring 44.

[0050] <Pressing part> Fig. 4 is a perspective view showing the pressing member 22 and the rotary seal ring 23. For convenience, the pressing member 22 and the rotary seal ring 23 are shown separated from each other in the axial direction in Fig. 4. In Figs. 3 and 4, the pressing member 22 is a member against which the rotary seal ring 23 is pressed from the other axial side.

[0051] The pressing member 22 is made of a plate member formed in an annular shape concentric with the rotary seal ring 23. The pressing member 22 is made of a material that is easy to process, similar to the pressing member 32 of the first embodiment. A side surface 220 on one axial side of the pressing member 22 is formed flat in the radial direction so that the entire side surface 220 is in surface contact with a side surface 21b1 on the other axial side of the annular portion 21b of the sleeve 21.

[0052] A plurality of grooves 222 recessed toward one side in the axial direction are formed at intervals (equally spaced in FIG. 4) in the circumferential direction on the side surface 221 on the other axial side of the pressing member 22. These grooves 222 are formed by cutting the base material of the pressing member 22 with a general-purpose machine tool. Each groove 222 is formed from a radial midpoint to a radial outer end of the pressing member 22. Each groove 222 is formed in a substantially U-shape when viewed from the other axial side. Each groove 222 is formed such that the circumferential groove width gradually increases from a radial midpoint to a radial outer end of the pressing member 22.

[0053] The pressing member 22 has a plurality of contact portions 223 protruding to the other axial side by forming a plurality of grooves 222. That is, the pressing member 22 has a plurality of contact portions 223 that are integrally formed at intervals in the circumferential direction on either side of the grooves 222. The plurality of contact portions 223 include a predetermined number of first contact portions 224 and a predetermined number of second contact portions 225.

[0054] The first abutment portions 224 and the second abutment portions 225 are the same in number and are arranged alternately in the circumferential direction of the pressing member 22. The pressing member 22 of this embodiment has eight abutment portions 223, and four first abutment portions 224 and four second abutment portions 225 are arranged alternately in the circumferential direction of the pressing member 22. The first abutment portions 224 and the second abutment portions 225 adjacent to each other in the circumferential direction are connected to each other radially inward of the recessed groove 222 in the pressing member 22.

[0055] The first contact portion 224 has a protruding end surface 224a which is a part of the side surface 221 of the pressing member 22. Similarly, the second contact portion 225 has a protruding end surface 225a which is another part of the side surface 221 of the pressing member 22.

[0056] End face 23b of the rotary seal ring 23, which is pressed by spring 43, abuts against side surface 221 of pressing member 22. A circumferential portion of end face 23b of the rotary seal ring 23 abuts against protruding end face 224a of first abutment portion 224. Another circumferential portion of end face 23b of the rotary seal ring 23 abuts against protruding end face 225a of second abutment portion 225 circumferentially adjacent to this first abutment portion 224.

[0057] A space S2 is formed in the recessed groove 222 between the first abutment portion 224 and the second abutment portion 225 that are adjacent in the circumferential direction. That is, the same number of spaces S2 as the recessed grooves 222 (here, eight spaces) are formed in the pressing member 22 at intervals in the circumferential direction. The spaces S2 allow a circumferential portion of the rotary seal ring 23 that corresponds to the spaces S2 to deform so as to protrude towards one axial side.

[0058] Since the pressure of the sealed fluid acts on the seal surface 23a of the rotary seal ring 23, the rotary seal ring 23 is pressed from the seal surface 23a toward the end face 23b in one axial direction. When the rotary seal ring 23 is pressed toward one axial direction by the elastic force of the spring 43 and the pressure of the sealed fluid, the end face 23b of the rotary seal ring 23 is pressed strongly against the protruding end faces 224a, 225a of the first abutment portion 224 and the second abutment portion 225 that are adjacent in the circumferential direction of the pressing member 22. Then, a portion of the rotary seal ring 23 corresponding to the space S2 is deformed so as to protrude toward one axial side within the space S2.

[0059] When the portion of the rotary seal ring 23 is deformed, an area D (indicated by a two-dot chain line in FIG. 4) in the seal surface 23a of the rotary seal ring 23 corresponding to the portion is slightly recessed toward one side in the axial direction, and a recess 23c is formed in the area D. As a result, a plurality of recesses 23c (eight in FIG. 4) are formed in the circumferential direction in the seal surface 23a of the rotary seal ring 23. The axial depth of each recess 23c is several μm. Note that the rotary seal ring 23 in FIGS. 3 and 4 shows a state before deformation.

[0060] The sealed fluid in the in-machine area A enters each recess 23c formed in the seal surface 23a of the rotary seal ring 23. As a result, a lubricating film is formed by the sealed fluid between both the seal surfaces 23a, 44a of the rotary seal ring 23 and the stationary seal ring 44, ensuring the lubrication of both the seal surfaces 23a, 44a.

[0061] <Action and effect> According to the mechanical seal 1 of this embodiment, the end face 23b on one axial side of the rotary seal ring 23 is strongly pressed against the first abutment portion 224 and the second abutment portion 225 of the pressing member 22 by the elastic force of the spring 43 and the pressure of the sealed fluid. As a result, a circumferential portion of the rotary seal ring 23 is deformed so as to protrude toward the space S2 formed between the circumferentially adjacent abutment portions 224, 225. Due to this deformation, the region D corresponding to the portion on the seal surface 23a of the rotary seal ring 23 is recessed toward one axial side, so that the recess 23c is formed in the region D. Therefore, by utilizing the elastic force of the spring 43 and the pressure of the sealed fluid, the recess 23c is formed on the seal surface 23a of the rotary seal ring 23, so that the recess 23c can be formed at low cost. In particular, when the rotary seal ring 23 is made of a hard material, it is difficult to machine a recess on the seal surface 23a of the rotary seal ring 23, so that the configuration of this embodiment is more effective.

[0062] The first contact portion 224 and the second contact portion 225 are formed as a unit integrally with the pressing member 22. Therefore, the first contact portion 224 and the second contact portion 225 can be attached to the casing 72 side simply by arranging the pressing member 22 on the inner periphery of the seal case 41. Therefore, the mechanical seal 1 can be easily assembled.

[0063] The pressing member 22 is formed in an annular shape concentric with the rotary seal ring 23. As a result, the first contact portion 224 and the second contact portion 225 can be formed at any circumferential position on the annular pressing member 22, and therefore the recess 23c can be formed at any circumferential position on the seal surface 23a of the rotary seal ring 23.

[0064] [others] In each of the above embodiments, the seal ring 33, 23 in which the recess 33c, 23c is formed may be made of a material other than a hard material. The shape of the pressing member 32, 22 in each of the above embodiments is not limited to annular, and may be any shape such as an arc. The shape of the recessed groove 322, 222 of the pressing member 32, 22 is not limited to the above embodiments, and may be any shape. The pressing member 32, 22 may have at least one first contact portion 324, 224 and one second contact portion 325, 225.

[0065] The pressing member 32 of the first embodiment may be used as the pressing member 22 of the second embodiment. In that case, when the pressing member 32 is disposed on one axial side of the rotating seal ring 23 in the second embodiment, the pressing member 32 may be disposed so that the abutment portion 323 protrudes on the other axial side.

[0066] Similarly, the pressing member 22 of the second embodiment may be used as the pressing member 32 of the first embodiment. In that case, when the pressing member 22 is disposed on the other axial side of the stationary seal ring 33 in the first embodiment, the pressing member 22 may be disposed so that the abutment portion 223 protrudes on one axial side.

[0067] In the first embodiment, the pressing member 32 is disposed on the other axial side of the stationary seal ring 33, but the recessed groove 322 portion of the pressing member 32 may be cut and only the first abutment portion 324 and the second abutment portion 325 may be disposed at intervals in the circumferential direction. Similarly, in the second embodiment, the pressing member 22 is disposed on one axial side of the rotary seal ring 23, but the recessed groove 222 portion of the pressing member 22 may be cut and only the first abutment portion 224 and the second abutment portion 225 may be disposed at intervals in the circumferential direction.

[0068] The description "first" of the contact portions 324, 224 and the description "second" of the contact portions 325, 225 are used to distinguish the words to which these descriptions are attached. Therefore, the terms "first" and "second" may be used in reverse.

[0069] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope of the claims and the meaning equivalent thereto. [Explanation of symbols]

[0070] 1 Mechanical seal 14 Spring (elastic member) 16 Rotating seal ring 16a Sealing surface 22 Pressing member 23 Rotating seal ring 23a Sealing surface 23b End face 23c Recess 32 Pressing member 33 Stationary sealing ring 33a Sealing surface 33b End face 33c Recess 43 Spring (elastic member) 44 Stationary sealing ring 44a Sealing surface 71 Rotational Axis 72 Casing 224 1st contact part 225 Second contact part 324 1st contact part 325 Second contact part A Cabin Area S1 space S2 space

Claims

1. a rotary seal ring provided on the rotary shaft side so as to be integrally rotatable with the rotary shaft and having a seal surface; a stationary seal ring provided on a casing surrounding the rotary shaft and having a seal surface facing the seal surface of the rotary seal ring; an elastic member that presses one of the rotary seal ring and the stationary seal ring toward the other, wherein the rotary seal ring and the stationary seal ring seal a sealed fluid in an in-machine area, a first abutment portion with which a part of an end face of at least one of the rotary seal ring and the stationary seal ring opposite to the seal surface abuts; a second abutment portion with which another portion of the end face of the one seal ring abuts, a space that allows deformation of the one seal ring toward the opposite side is formed between the first contact portion and the second contact portion.

2. a pressing member disposed on the opposite side of the one seal ring, The mechanical seal according to claim 1 , wherein the pressing member has the first contact portion and the second contact portion.

3. The mechanical seal according to claim 2 , wherein the pressing member is formed in an annular shape concentric with the one seal ring.

4. The mechanical seal according to claim 1 , wherein the one seal ring is made of a hard material.

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