Mechanical seal

Abstract

To provide a mechanical seal capable of restraining damage of a stationary seal ring caused by its regulation, while regulating co-rotation of the stationary seal ring with a rotary seal ring.SOLUTION: A mechanical seal of the present disclosure includes a seal case that surrounds a rotating shaft, a stationary seal ring that is disposed in the seal case and has an engaged portion formed of a groove or a hole, a rotating seal ring that is provided on the rotating shaft so as to be integrally rotatable and slides on the stationary seal ring, a regulating member that is fixed to the seal case, is inserted into the engaged portion, and regulates co-rotation of the stationary seal ring with the rotating seal ring, and a buffer member that is provided in one of the engaged portion and the regulating member and alleviates contact between the engaged portion and the regulating member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to mechanical seals. [Background technology]

[0002] For example, the mechanical seal described in Patent Document 1 includes a stationary seal ring (fixed member) provided in a seal case, a rotary seal ring (rotating member) provided on a rotating shaft and sliding against the stationary seal ring, and a restriction pin (support member) that restricts the stationary seal ring from rotating together with the rotary seal ring. One axial side of the restriction pin is fixed to the seal case, and the other axial side of the restriction pin is inserted into a hole formed in the stationary seal ring. The outer peripheral surface of the restriction pin comes into contact with the inner peripheral surface of the hole, thereby restricting the stationary seal ring from rotating together with the rotary seal ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-200849 Summary of the Invention [Problem to be solved by the invention]

[0004] If the mechanical seal is used in equipment in which the rotary shaft is frequently started and stopped, or in equipment in which the rotary shaft is rotated forward and backward, the frequency of contact between the stationary seal ring and the regulating pin increases, which may result in damage to the stationary seal ring.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide a mechanical seal that can restrict the stationary seal ring from rotating together with the rotating seal ring, while suppressing damage to the stationary seal ring that would otherwise result from this restriction. [Means for solving the problem]

[0006] (1) The mechanical seal of the present disclosure comprises a seal case surrounding a rotating shaft, a stationary seal ring disposed within the seal case and having an engaged portion formed of a groove or a hole, a rotary seal ring rotatable integrally with the rotating shaft and sliding against the stationary seal ring, a restricting member fixed to the seal case and inserted into the engaged portion to restrict the stationary seal ring from rotating together with the rotary seal ring, and a buffer member disposed on either the engaged portion or the restricting member to reduce contact between the engaged portion and the restricting member.

[0007] According to the mechanical seal of the present disclosure, the restricting member fixed to the seal case is inserted into the engaged portion of the stationary seal ring, thereby restricting the stationary seal ring from rotating together with the rotary seal ring. In addition, the buffer member reduces contact between the engaged portion and the restricting member, thereby preventing damage to the stationary seal ring due to contact between the engaged portion and the restricting member.

[0008] (2) In the mechanical seal of (1) above, it is preferable that the regulating member is cylindrical, and the buffer member is an O-ring provided on the outer periphery of the regulating member. In this case, damage to the stationary seal ring due to contact between the engaged portion and the restricting member can be suppressed by a simple configuration using a general-purpose O-ring.

[0009] (3) In the mechanical seal of (2), it is preferable that the stationary seal ring is movable in the axial direction relative to the seal case, the restricting member has an annular groove formed on its outer periphery into which the O-ring is fitted, and the annular groove is formed to have a concave cross section. In this case, the O-ring is fitted into an annular groove with a concave cross section formed on the outer periphery of the restricting member, so that the O-ring can be prevented from slipping out of the annular groove when the stationary seal ring moves axially relative to the seal case.

[0010] (4) In the mechanical seal of (3) above, the cross-sectional area of ​​the O-ring is preferably smaller than the spatial cross-sectional area of ​​the annular groove. In this case, when the stationary seal ring moves in the axial direction relative to the seal case, the O-ring can be further prevented from slipping out of the annular groove.

[0011] (5) In any of the mechanical seals (2) to (4), the engaged portion is formed to extend in the axial direction of the stationary seal ring, and the cross-sectional center position of the O-ring is preferably located within an axial range of ±20% of the total axial length of the engaged portion relative to the axial center position of the engaged portion. In this case, when the stationary seal ring moves axially relative to the seal case, the O-ring can be prevented from slipping out of the engaged portion in the axial direction. Therefore, even if the stationary seal ring 32 moves axially relative to the seal case 31, the O-ring can reliably reduce contact between the engaged portion and the restricting member. [Effects of the Invention]

[0012] According to the mechanical seal of the present disclosure, the stationary seal ring is restricted from rotating together with the rotary seal ring, and damage to the stationary seal ring caused by this restriction can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view illustrating a mechanical seal according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the periphery of a stationary seal ring of the mechanical seal. [Figure 3] FIG. 3 is an enlarged cross-sectional view of part I in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, preferred embodiments will be described with reference to the accompanying drawings. [Overall configuration] Fig. 1 is a cross-sectional view showing a mechanical seal according to an embodiment of the present disclosure. In Fig. 1, the mechanical seal 1 of this embodiment is a mechanical seal that seals a sealed fluid (solvent, water, oil, etc.) inside a rotating device such as a pump or a mixer. The mechanical seal 1 is disposed along the axial direction of the rotating shaft 71 between a rotating shaft 71 of the rotating device and a casing 72 that surrounds the rotating shaft 71.

[0015] Hereinafter, in this specification, the "axial direction" refers to the direction along the axis X of the rotating shaft 71. The "radial direction" refers to the direction perpendicular to the axis X of the rotating shaft 71. The "circumferential direction" refers to the direction around the axis X of the rotating shaft 71. For convenience, in this specification, the left side of FIG. 1 (outside the machine) will be referred to as one axial side, and the right side of FIG. 1 (inside the machine) will be referred to as the other axial side.

[0016] The mechanical seal 1 of this embodiment is a so-called inside-type mechanical seal. The mechanical seal 1 includes a rotating unit 2 provided on a rotating shaft 71 so as to be rotatable integrally therewith, and a stationary unit 3 provided on a casing 72.

[0017] [Rotation unit] The rotating unit 2 is disposed within a seal case 31 (described later) of the stationary unit 3. The rotating unit 2 includes a first retainer 11, a second retainer 12, a third retainer 13, and a rotary seal ring 14. The first retainer 11, the second retainer 12, and the third retainer 13 are each formed in an annular shape. The first retainer 11 is fitted into an annular groove 71a formed on the outer periphery of the rotating shaft 71. The first retainer 11 is fixed to the rotating shaft 71 by a plurality of set screws 15 being radially fastened therein.

[0018] The second retainer 12 and the third retainer 13 are fixed to the radially outer and inner sides, respectively, of one axial side of the first retainer 11. A seal (secondary seal) is formed between the first retainer 11 and the second retainer 12 by an O-ring 16. A seal (secondary seal) is formed between the first retainer 11 and the third retainer 13 by an O-ring 17.

[0019] The rotary seal ring 14 is held between the second retainer 12 and the third retainer 13 on one axial side of the first retainer 11. The rotary seal ring 14 is made of, for example, silicon carbide (SiC), which has excellent wear resistance and sealing performance. A seal end face 14a is formed on one axial side of the rotary seal ring 14. Relative rotation of the rotary seal ring 14 with respect to the first retainer 11 is restricted by a pin 18 fixed to the first retainer 11. An O-ring 19 provides a seal (secondary seal) between the rotary seal ring 14 and the second retainer 12.

[0020] [Stationary Unit] The stationary unit 3 includes a seal case 31 fixed to a casing 72. The seal case 31 surrounds the rotary shaft 71. The seal case 31 has an annular first case body 311, a cylindrical second case body 312, an annular third case body 313, an annular fourth case body 314, and an annular fifth case body 315.

[0021] The first case body 311 is fixed to the casing 72 by bolts 51 while abutting against one axial side surface of the casing 72. The inner peripheral surface of the first case body 311 is close to the outer peripheral surface of the rotating shaft 71. An O-ring 41 provides a seal (secondary seal) between the first case body 311 and the casing 72.

[0022] The second case body 312 and the third case body 313 are arranged in this order on one axial side of the first case body 311. The second case body 312 and the third case body 313 are fixed to the first case body 311 by bolts 52. An O-ring 42 seals (secondary seal) between the first case body 311 and the second case body 312. An O-ring 43 seals (secondary seal) between the second case body 312 and the third case body 313.

[0023] The inner diameter of the second case body 312 is larger than the outer diameter of the first retainer 11. The inner diameter of the third case body 313 is smaller than, for example, the outer diameter of the rotary seal ring 14. The rotary unit 2 is housed in an annular space formed between the first case body 311 and the third case body 313 and between the second case body 312 and the rotary shaft 71.

[0024] The fourth case body 314 and the fifth case body 315 are arranged in this order on one axial side of the third case body 313. The inner diameters of the fourth case body 314 and the fifth case body 315 are smaller than the inner diameter of the third case body 313. The inner peripheral surfaces of the fourth case body 314 and the fifth case body 315 are close to the outer peripheral surface of the rotating shaft 71.

[0025] The fourth case body 314 is fixed to the third case body 313 by bolts 53. An O-ring 44 provides a seal (secondary seal) between the third case body 313 and the fourth case body 314. The fourth case body 314 has a protruding portion 314b that protrudes along the inner circumferential surface of the third case body 313 toward the other axial direction. The protruding portion 314b is formed in a cylindrical shape. A notch 314a that opens toward one axial direction is formed on the inner periphery of the fourth case body 314. The notch 314a is formed in an annular shape around the entire circumference of the fourth case body 314.

[0026] The fifth case body 315 is fixed to the fourth case body 314 with bolts 54. An O-ring 45 provides a seal (secondary seal) between the fourth case body 314 and the fifth case body 315. A notch 315a that opens to the other axial side is formed on the inner periphery of the fifth case body 315. The notch 315a is formed in an annular shape around the entire circumference of the fifth case body 315. The notch 315a of the fifth case body 315 communicates with the notch 314a of the fourth case body 314.

[0027] The stationary unit 3 further includes a stationary seal ring 32 , a buffer member 33 , a plurality of restricting members 34 , a plurality of elastic members 35 , a transmission member 36 , an adapter ring 37 , and a segment ring 38 arranged in the seal case 31 .

[0028] The stationary seal ring 32 is disposed radially inward of the third case body 313 within the seal case 31, and is disposed next to one axial side of the rotary seal ring 14. The stationary seal ring 32 is made of, for example, silicon carbide (SiC), which has excellent wear resistance and sealing performance, similar to the rotary seal ring 14.

[0029] One axial end of the stationary seal ring 32 is fitted axially movably within the protruding portion 314b of the fourth case body 314. A seal (secondary seal) is formed between the stationary seal ring 32 and the seal case 31 by an O-ring 46. The other axial end face of the stationary seal ring 32 forms an annular seal end face 32a against which the seal end face 14a of the rotary seal ring 14 slides.

[0030] A plurality of grooves 32b, which are engaged portions, are formed at equal intervals in the circumferential direction on the inner circumference of the stationary seal ring 32. Each groove 32b is formed, for example, with a U-shaped cross section that opens at the inner circumferential surface of the stationary seal ring 32. Each groove 32b is formed to extend in the axial direction of the stationary seal ring 32. In this embodiment, each groove 32b is formed over the entire axial direction of the stationary seal ring 32.

[0031] 2 is an enlarged cross-sectional view showing the periphery of the stationary seal ring 32. In FIG. 2, the same number of regulating members 34 as the number of grooves 32b of the stationary seal ring 32 are fixed to the inner periphery of the fourth case body 314. The regulating members 34 are made of metal and have a degree of rigidity that prevents them from breaking due to the sliding torque of the mechanical seal 1. The regulating members 34 are formed, for example, in a cylindrical shape. A male thread 34a is formed on the outer periphery of one axial end of the regulating member 34. The male thread 34a of the regulating member 34 is screwed into a threaded hole 314c formed on the inner periphery of the fourth case body 314.

[0032] The restricting member 34 has a restricting projection 34b that protrudes further axially toward the other side than the fourth case body 314. The restricting projection 34b is inserted into the groove 32b of the stationary seal ring 32. As a result, the restricting member 34 prevents the stationary seal ring 32 from rotating relative to the seal case 31, and restricts the stationary seal ring 32 from rotating together with the rotary seal ring 14.

[0033] An annular groove 34c is formed on the outer periphery of the other axial side of the restricting protrusion 34b. In this embodiment, the annular groove 34c is formed to have a concave cross section. A buffer member 33 is provided in the annular groove 34c. The buffer member 33 is, for example, an O-ring, and is fitted into the annular groove 34c.

[0034] Figure 3 is an enlarged cross-sectional view of portion I in Figure 2. The stationary seal ring 32 is not shown in Figure 3. In Figures 2 and 3, the outer diameter D1 of the O-ring (buffer member) 33 is larger than the outer diameter D2 of the restricting projection 34b. As a result, the outer periphery of the O-ring 33 protrudes radially outward beyond the outer periphery of the restricting projection 34b. Therefore, when the stationary seal ring 32 rotates together with the rotating seal ring 14, the inner surface of the groove 32b of the stationary seal ring 32 comes into contact with the O-ring 33 before coming into contact with the outer periphery of the restricting projection 34b. This reduces contact between the groove 32b of the stationary seal ring 32 and the restricting projection 34b.

[0035] As shown in Fig. 3, the cross-sectional area S1 of the O-ring 33 (the area of ​​the region shown by single hatching in Fig. 3) is smaller than the spatial cross-sectional area S2 of the annular groove 34c (the area of ​​the region shown by cross hatching in Fig. 3). As shown in Fig. 2, the cross-sectional center position P1 of the O-ring 33 is located within an axial range of ±20% of the total axial length L of the groove 32b with respect to the axial center position P2 of the groove 32b of the stationary seal ring 32.

[0036] In FIG. 1 , the elastic member 35 is a member that presses the stationary seal ring 32 toward the other axial side (toward the rotary seal ring 14). The elastic member 35 in this embodiment is, for example, a compression coil spring. The elastic member 35 is inserted into a through hole 314d formed in the inner periphery of the fourth case body 314. The through holes 314d are formed in the fourth case body 314 at different circumferential positions with respect to the threaded hole 314c and are formed at equal intervals in the circumferential direction. An elastic member 35 is inserted into each of the plurality of through holes 314d. The other axial end of the elastic member 35 protrudes further toward the other axial side than the fourth case body 314 and abuts against a side surface of the transmission member 36 on one axial side.

[0037] 1 and 2, the transmission member 36 is interposed between the elastic member 35 and the stationary seal ring 32. The transmission member 36 is formed in the shape of an annular plate, and transmits the pressing force of the multiple elastic members 35 evenly over the entire circumference of the stationary seal ring 32. The side surface on the other axial side of the transmission member 36 abuts against the end face on one axial side of the stationary seal ring 32. Grooves 36a are formed on the inner circumference of the transmission member 36, the same number as the grooves 32b of the stationary seal ring 32. The restricting protrusions 34b of the restricting member 34 pass through the grooves 36a of the transmission member 36 and are inserted into the grooves 32b of the stationary seal ring 32.

[0038] The adapter ring 37 is formed in an annular shape and is fitted into the notch 314a of the fourth case body 314. The adapter ring 37 is fixed to the fourth case body 314 with bolts (not shown). One axial end of the elastic member 35 abuts against the other axial side surface of the adapter ring 37. By fitting and fixing the adapter ring 37 into the notch 314a of the fourth case body 314, the elastic member 35 is compressed in the axial direction.

[0039] The segment ring 38 is formed in an annular shape and is fitted into the cutout portion 315a of the fifth case body 315. A side surface on the other axial side of the segment ring 38 abuts against a side surface on one axial side of the adapter ring 37. Relative rotation of the segment ring 38 with respect to the adapter ring 37 is restricted by a pin 47 fixed to the adapter ring 37.

[0040] With the above configuration, the elastic member 35 presses the stationary seal ring 32 toward the other axial side, so that the seal end face 32a of the stationary seal ring 32 comes into close contact with the seal end face 14a of the rotary seal ring 14. As a result, when the rotary seal ring 14 rotates together with the rotary shaft 71, the seal end face 14a of the rotary seal ring 14 slides while coming into close contact with the seal end face 32a of the stationary seal ring 32. Therefore, within the seal case 31, a sealed space 73 that seals the sealed fluid is formed radially outward of the sliding portion between the seal end face 14a of the rotary seal ring 14 and the seal end face 32a of the stationary seal ring 32.

[0041] [Action and effect] According to the mechanical seal 1 of this embodiment, the restricting member 34 fixed to the seal case 31 (fourth case body 314) is inserted into the groove 32b of the stationary seal ring 32, thereby restricting the stationary seal ring 32 from rotating together with the rotary seal ring 14. In addition, the buffer member 33 reduces contact between the groove 32b of the stationary seal ring 32 and the restricting member 34, thereby preventing damage to the stationary seal ring 32 caused by contact between the groove 32b and the restricting member 34.

[0042] In particular, in the case of a mechanical seal 1 having a stationary seal ring 32 made of SiC, which is a brittle material, and a restricting member 34 made of a rigid metal, as in this embodiment, the stationary seal ring 32 is easily damaged by contact with the restricting member 34, so it is more effective to use the buffer member 33. Furthermore, because the restricting member 34 is made of a rigid metal, it is possible to effectively prevent the restricting member 34 from breaking due to the sliding torque of the mechanical seal 1.

[0043] The buffer member 33 is an O-ring provided on the outer periphery of the regulating member 34, and therefore the simple configuration using the general-purpose O-ring 33 can suppress damage to the stationary seal ring 32 caused by contact between the groove 32b and the regulating member 34.

[0044] The O-ring 33 is fitted into an annular groove 34c having a concave cross section that is formed on the outer periphery of the restricting member 34. This makes it possible to prevent the O-ring 33 from slipping out of the annular groove 34c when the stationary seal ring 32 moves to the other axial side relative to the seal case 31 due to the pressing force of the elastic member 35. As a result, the sliding resistance of the O-ring 33 against the stationary seal ring 32 can be reduced, making it possible to reduce the inhibition, due to the sliding resistance, of the ability of the stationary seal ring 32 to follow the pressing force of the elastic member 35 to the other axial side.

[0045] The cross-sectional area S1 of the O-ring 33 is smaller than the spatial cross-sectional area S2 of the annular groove 34c. This makes it possible to further prevent the O-ring 33 from slipping out of the annular groove 34c when the stationary seal ring 32 moves axially to the other side relative to the seal case 31 due to, for example, the pressing force of the elastic member 35. This makes it possible to further reduce the sliding resistance of the O-ring 33 against the stationary seal ring 32, thereby further reducing the impairment of the followability of the stationary seal ring 32 caused by the sliding resistance.

[0046] The cross-sectional center position P1 of the O-ring 33 is located within an axial range of ±20% of the total axial length L of the groove 32b with respect to the axial center position P2 of the groove 32b of the stationary seal ring 32. This makes it possible to prevent the O-ring 33 from slipping out to both sides of the groove 32b in the axial direction when the stationary seal ring 32 moves axially relative to the seal case 31. Therefore, even if the stationary seal ring 32 moves axially relative to the seal case 31, the O-ring 33 can reliably reduce contact between the groove 32b of the stationary seal ring 32 and the restricting member 34.

[0047] The groove 32b is formed over the entire axial length of the stationary seal ring 32 (FIG. 2), but may be formed in an axial range excluding the other axial end of the stationary seal ring 32. In other words, the groove 32b may have an end face on the other axial side of the stationary seal ring 32 that faces the end face of the restricting member 34 on the other axial side. In this case, the cross-sectional center position P1 of the O-ring 33 is positioned within an axial range of ±20% of the total axial length L of the groove 32b relative to the axial center position P2 of the groove 32b, thereby achieving the following effects.

[0048] It is possible to prevent the O-ring 33 from slipping out of the groove 32b to one axial side when the stationary seal ring 32 moves to the other axial side relative to the seal case 31. As a result, even if the stationary seal ring 32 moves to the other axial side relative to the seal case 31, the O-ring 33 can reliably reduce contact between the groove 32b of the stationary seal ring 32 and the restricting member 34. Furthermore, when the stationary seal ring 32 moves in one axial direction relative to the seal case 31, the end face on the other axial side of the groove 32b can be prevented from coming into contact with the end face on the other axial side of the restricting member 34. This further prevents damage to the stationary seal ring 32 due to contact between the groove 32b and the restricting member 34.

[0049] [others] The buffer member 33 is not limited to an O-ring, and may be, for example, a soft cushioning material. Furthermore, a plurality of buffer members 33 may be provided in the axial direction on the outer periphery of the restricting member 34. In this case, the restricting member 34 may be provided with the same number of annular grooves 34c as the number of buffer members 33. Furthermore, although the buffer member 33 in the above embodiment is provided on the outer periphery of the restricting member 34, it may also be provided in the groove 32b (engaged portion) of the stationary seal ring 32.

[0050] In the above embodiment, the engaged portion is the groove 32b that opens on the inner circumferential surface of the stationary seal ring 32, but it may also be a hole that does not open on the inner circumferential surface. The annular groove 34c of the restricting member 34 in the above embodiment is formed with a concave cross section, but is not limited to this. For example, the annular groove 34c may be formed with a V-shaped cross section.

[0051] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the above-described embodiments, but is defined by the claims, and includes all modifications within the meaning and scope equivalent to the configurations described in the claims. [Explanation of symbols]

[0052] 1 Mechanical seal 14 Rotating seal ring 31 Seal Case 32 Stationary sealing ring 32b Groove (engaged part) 33 Cushioning material (O-ring) 34 Regulatory components 34c Annular groove 71 Rotation axis L Total axial length P1 Cross section center position P2 center position S1 cross-sectional area S2 spatial cross section

Claims

1. a seal case surrounding the rotating shaft; a stationary seal ring disposed in the seal case and having an engaged portion formed of a groove or a hole; a rotary seal ring that is provided on the rotary shaft so as to be rotatable integrally with the rotary shaft and that slides against the stationary seal ring; a restricting member that is fixed to the seal case and inserted into the engaged portion, and that restricts the stationary seal ring from rotating together with the rotary seal ring; a buffer member provided on one of the engaged portion and the regulating member, the buffer member buffering contact between the engaged portion and the regulating member.

2. The restricting member has a cylindrical shape, 2. The mechanical seal according to claim 1, wherein the buffer member is an O-ring provided on the outer periphery of the restricting member.

3. the stationary seal ring is axially movable relative to the seal case, An annular groove into which the O-ring is fitted is formed on the outer periphery of the restricting member, The mechanical seal according to claim 2 , wherein the annular groove is formed to have a concave cross section.

4. The mechanical seal according to claim 3 , wherein the cross-sectional area of ​​the O-ring is smaller than the spatial cross-sectional area of ​​the annular groove.

5. The engaged portion is formed to extend in the axial direction of the stationary seal ring, 5. A mechanical seal according to claim 2, wherein the cross-sectional center position of the O-ring is located within an axial range of ±20% of the total axial length of the engaged portion relative to the axial center position of the engaged portion.

Images