JP6612092B2 - mechanical seal - Google Patents

Description

  The present invention relates to a mechanical seal.

  Conventionally, as a seal (primary seal) for a sealed fluid inside a rotary fluid device, a metal stationary seal ring fixed to the casing side and a rotary seal ring attached to the rotary shaft side so as to be integrally rotatable. And a mechanical seal in which a stationary side sealing end surface formed on the stationary sealing ring and a rotation side sealing end surface formed on the rotation sealing ring are in sliding contact with each other are often used. As such a mechanical seal, as shown in FIG. 3, a stationary sealing ring 102 is fitted and fixed to the casing 101, and both axial ends between the inner periphery of the casing 101 and the outer periphery of the stationary sealing ring 102 are provided. In some cases, a rubber O-ring 103 and a thermally conductive gasket 104 are used for sealing (secondary sealing) (see, for example, Patent Document 1).

  A retainer 106 and a rotary seal ring 107 are attached to the rotary shaft 105 so as to be integrally rotatable. The rotation-side sealing end surface 107 a of the rotation sealing ring 107 seals the fluid to be sealed by being pressed against the stationary-side sealing end surface 102 a of the stationary sealing ring 102 by the urging force of the spring 108 held by the retainer 106.

Japanese Patent Laid-Open No. 64-21272 (see FIG. 1)

  Generally, in this type of mechanical seal, when the rotary shaft 105 rotates at high speed, sliding heat is generated on the stationary side sealing end surface 102a of the stationary sealing ring 102 due to sliding with the rotation side sealing end surface 107a of the rotary sealing ring 107. To do. In addition, when sealing a high temperature sealed fluid, the stationary sealing ring 102 in contact with the sealed fluid is also at a high temperature. When the stationary sealing ring 102 becomes high in this manner, surface roughness or abnormal wear may occur on the stationary-side sealing end surface 102a, and the sealing performance as the primary seal may be reduced. For this reason, it is necessary to efficiently radiate the heat generated in the stationary seal ring 102 to the casing 101 side.

  However, in the mechanical seal, since the rubber O-ring 103 is interposed between the casing 101 and the stationary seal ring 102 in the secondary seal portion by the O-ring 103, the heat generated in the stationary seal ring 102 is present. Cannot be efficiently radiated to the casing 101 side. Further, since the gasket 104 having thermal conductivity is interposed between the casing 101 and the stationary sealing ring 102 in the secondary seal portion by the gasket 104, the heat dissipation performance is higher than that of the O-ring 103. There was a problem that the sealing performance was inferior to that of the ring 103.

    The present invention has been made in view of the above problems, and an object of the present invention is to provide a mechanical seal capable of enhancing the heat dissipation performance from the stationary seal ring to the casing without deteriorating the seal performance.

  A mechanical seal according to the present invention includes a rotary seal ring attached to a rotary shaft so as to be integrally rotatable, and a stationary seal ring fixed to a casing side surrounding the rotary shaft and in sliding contact with the rotary seal ring. An annular first seal surface formed on the inner periphery on the casing side, and an annular second seal formed on the outer periphery of the stationary seal ring so as to face the first seal surface A seal portion that seals between the surfaces, and the seal portion includes a rubber O-ring and an annular gasket that is disposed radially outside or radially inside the O-ring and has thermal conductivity. It is characterized by that.

  According to the present invention, since the seal portion that seals between the first seal surface on the casing side and the second seal surface of the stationary seal ring has the rubber O-ring, the first seal surface and the second seal surface The sealing performance between the two can be ensured. In addition, since the seal portion includes a thermally conductive gasket disposed on the radially outer side or radially inner side of the O-ring, the heat generated in the stationary seal ring is efficiently radiated to the casing side via the gasket. can do. Therefore, the heat dissipation performance from the stationary seal ring to the casing can be enhanced without reducing the seal performance.

  In the mechanical seal, it is preferable that the gasket is disposed on a radially outer side of the O-ring. In this case, the seal portion can be easily assembled as compared with the case where the gasket is disposed on the radially inner side of the O-ring.

In the mechanical seal, the first seal surface and the second seal surface are disposed so as to face each other in the axial direction of the rotating shaft, and one side surface of the gasket in the axial direction directly faces the first seal surface. It is preferable that the other axial side surface of the gasket is in direct surface contact with the second seal surface.
In this case, since both side surfaces of the gasket in the axial direction are in direct surface contact with the first seal surface on the casing side and the second seal surface of the stationary seal ring, the heat generated in the stationary seal ring is transferred to the casing side via the gasket. It is possible to dissipate heat more efficiently.

  According to the mechanical seal of the present invention, the heat dissipation performance from the stationary seal ring to the casing can be enhanced without reducing the seal performance.

It is sectional drawing which shows the mechanical seal which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the mechanical seal which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the conventional mechanical seal.

Hereinafter, embodiments of a mechanical seal of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing a mechanical seal according to the first embodiment of the present invention. In FIG. 1, a mechanical seal 1 is provided in a rotating fluid device such as a pump used in a chemical plant, for example, and seals a sealed fluid (for example, ethylene) having a large pressure fluctuation. The mechanical seal 1 of the present embodiment is an outside type mechanical seal disposed between a rotating shaft 60 and a casing 50 of a rotating fluid device that surrounds the rotating shaft 60. In the present embodiment, the left side in FIG. 1 is referred to as the outboard side, and the right side in FIG.

  The mechanical seal 1 is fitted as a rotation-side unit with a retainer 2 attached to the rotary shaft 60 so as to be rotatable integrally with the rotary shaft 60 so as to be rotatable integrally with the rotary shaft 60 and movable in the axial direction (left-right direction in the figure). An annular rotary seal ring 3 and an elastic member 4 that urges the rotary seal ring 3 toward the inside of the machine are provided.

  The retainer 2 is a cylindrical body having an L-shaped cross section including a first holding part 21 having a small diameter formed in a cylindrical shape and a second holding part 22 having a large diameter integrally formed on the outer side of the retainer 2. . The first holding part 21 and the second holding part 22 hold a plurality of elastic members 4 arranged in the circumferential direction. The second holding part 22 is fixed to the rotating shaft 60 by a predetermined number of set screws 11 arranged in the circumferential direction.

  The rotary seal ring 3 is made of a hard material such as ceramics or cemented carbide excellent in wear resistance and sealing performance. The rotary seal ring 3 includes a main body 31, a connecting portion 32 that is integrally formed on the outer side of the main body 31, and a reinforcing portion 33 that is a drive collar attached to an end surface on the outer side of the connecting portion 32. ing.

The inner diameter of the main body 31 is set slightly larger than the outer diameter of the rotating shaft 60. A rotary side sealing end face 31 a is formed at the end of the main body 31 on the machine inner side.
The inner diameter of the connecting portion 32 is set slightly larger than the outer diameter of the first holding portion 21 of the retainer 2. The connecting portion 32 is movable in the axial direction together with the main body portion 31 and the reinforcing portion 33 in a state where the inner peripheral surface on the inside of the machine is sealed (secondary seal) by the O-ring 12 with respect to the outer peripheral surface of the rotary shaft 60. Is held in.

  The reinforcing portion 33 is a drive collar made of a metal material such as stainless steel (for example, SUS316). A drive pin 13 protruding to the inside of the machine is fixed to the reinforcing part 33, and this drive pin 13 is engaged with an engagement hole 32 a formed at the end of the connection part 32 on the outside of the machine. Thereby, the reinforcing part 33 is prevented from rotating relative to the main body part 31 and the connecting part 32.

  The elastic member 4 is made of, for example, a compression coil spring and is held by the second holding portion 22 of the retainer 2. The end of the elastic member 4 on the machine inner side is in contact with the end surface of the reinforcing part 33 on the machine outer side, and the urging force of the elastic member 4 urges the rotary seal ring 3 toward the machine inner side in the axial direction. Thereby, the rotation-side sealing end surface 31 a of the rotation sealing ring 3 is pressed against a stationary-side sealing end surface 6 a described later by the urging force of the elastic member 4.

  The casing 50 includes a casing body 51 and a seal case 52 fixed to the side surface of the casing body 51 on the outside of the machine. The mechanical seal 1 is, as a stationary side unit, an annular stationary sealing ring 6 fitted in the sealing case 52 and a pair of sealing portions 7 that seal between the inner periphery of the sealing case 52 and the outer periphery of the stationary sealing ring 6. , 8 are provided.

  The stationary seal ring 6 is a member formed of carbon or other material as a main component, and the outer peripheral surface 6 b is fitted and fixed to the inner peripheral surface 52 a of the seal case 52. The end face on the machine outside of the stationary seal ring 6 is a stationary side seal end face 6a with which the rotary side seal end face 31a of the rotary seal ring 3 is in sliding contact. A conical surface 6c is formed on the inner peripheral surface of the stationary seal ring 6 so as to gradually increase in diameter from the outer side in the axial direction toward the inner side.

  An annular seal surface (first seal surface) 52b extending in the radial direction is formed on the outer side of the inner peripheral portion of the seal case 52. An annular seal surface (second seal surface) 6 d that is axially opposed to the seal surface 52 b of the seal case 52 is formed on the outer side of the outer peripheral portion of the stationary seal ring 6. The seal portion 7 seals between the seal surface 52 b of the seal case 52 and the seal surface 6 d of the stationary seal ring 6.

  The seal portion 7 is made of rubber (for example, synthetic rubber such as nitrile rubber or fluorine rubber), and a material having heat conductivity (copper, aluminum, SUS, etc.) disposed outside the O-ring 7a in the radial direction. And an annular gasket 7b made of expanded graphite or the like. Here, the “gasket” in the present invention refers to a material made of a material having a higher thermal conductivity than an O-ring arranged on the radially inner side. For example, the gasket 7b of this embodiment is made of copper having a Brinell hardness (HB) of 50 and a thermal conductivity of 400 W / (m · K).

The O-ring 7a is formed in an elliptical cross section, and its axial dimension is set longer than the axial dimension of the gasket 7b. Thereby, the crushing allowance of the O-ring 7a is set larger than the crushing allowance of the gasket 7b.
One side surface 7b1 in the axial direction of the gasket 7b is in direct surface contact with the seal surface 52b of the seal case 52. Further, the other axial side surface 7 b 2 of the gasket 7 b is in direct surface contact with the sealing surface 6 d of the stationary sealing ring 6.

  An annular seal surface (first seal surface) 51 b that protrudes to the outside of the machine is formed on the side surface of the casing body 51 on the outside of the machine. An annular seal surface (second seal surface) 6 e that is axially opposed to the seal surface 51 b of the casing main body 51 is formed on the machine inner side of the outer peripheral portion of the stationary seal ring 6. The seal portion 8 seals between the seal surface 51 b of the casing body 51 and the seal surface 6 e of the stationary seal ring 6.

  The seal portion 8 is made of rubber (for example, synthetic rubber such as nitrile rubber or fluorine rubber), and a material (copper, aluminum, SUS, or the like) disposed on the outer side in the radial direction of the O-ring 8a. And an annular gasket 8b made of expanded metal or the like. The gasket 8b of the present embodiment is made of copper having a Brinell hardness (HB) of 50 and a thermal conductivity of 400 W / (m · K), for example, like the gasket 7b.

The O-ring 8a is formed in an elliptical cross section, and its axial dimension is set longer than the axial dimension of the gasket 8b. Thereby, the crushing margin of the O-ring 8a is set larger than the crushing margin of the gasket 8b.
One side surface 8 b 1 in the axial direction of the gasket 8 b is in direct surface contact with the seal surface 51 b of the casing body 51. Further, the other axial side surface 8 b 2 of the gasket 8 b is in direct surface contact with the sealing surface 6 e of the stationary sealing ring 6.

  According to the mechanical seal 1 of the present embodiment configured as described above, a seal that seals between the first seal surface 52b (51b) on the casing 50 side and the second seal surface 6d (6e) of the stationary seal ring. Since the part 7 (8) has the rubber O-ring 7a (8a), the sealing performance between the first seal surface 52b (51b) and the second seal surface 6d (6e) can be ensured. Further, since the seal portion 7 (8) has a metal gasket 7b (8b) disposed on the outer side in the radial direction of the O-ring 7a (8a), heat such as sliding heat generated in the stationary seal ring 6 is generated. Heat can be efficiently radiated to the casing 50 through the gasket 7b (8b). Therefore, the heat dissipation performance from the stationary seal ring 6 to the casing 50 can be enhanced without reducing the sealing performance. Therefore, the mechanical seal 1 is particularly suitable when sealing a high-temperature sealed fluid or when large sliding heat is generated during dry operation or the like.

  Further, since the gasket 7b (8b) is disposed on the outer side in the radial direction of the O-ring 7a (8a), compared with the case where the gasket 7b (8b) is disposed on the inner side in the radial direction of the O-ring 7a (8a), The seal portion 7 (8) can be easily assembled.

  Further, both axial side surfaces 7b1, 7b2 (8b1, 8b2) of the gasket 7b (8b) are formed on the first seal surface 52b (51b) on the casing 50 side and the second seal surface 6d (6e) of the stationary seal ring 6. Since they are in direct surface contact with each other, sliding heat generated in the stationary seal ring 6 can be radiated more efficiently to the casing 50 side via the gasket 7b (8b).

  FIG. 2 is a sectional view showing a mechanical seal according to the second embodiment of the present invention. The mechanical seal 1 of the present embodiment is different from the first embodiment in that it is an inside type mechanical seal. In the present embodiment, the right side of FIG. 2 is referred to as the inside of the machine, and the left side of FIG. 2 is referred to as the outside of the machine.

  In FIG. 2, the mechanical seal 1 of the present embodiment includes a retainer 2 attached to a rotary shaft 60 so as to be integrally rotatable with a rotary shaft 60 as a rotary side unit, and can rotate integrally with the rotary shaft 60 in the axial direction (left and right in the figure). And an annular rotary seal ring 3 that is movably fitted in the direction) and an elastic member 4 that biases the rotary seal ring 3 toward the outside of the machine.

The retainer 2 is formed in a cylindrical shape, and is fixed to the rotating shaft 60 by a predetermined number of set screws 11 arranged in the circumferential direction. The retainer 2 holds an elastic member 4.
The rotary seal ring 3 includes a main body 31, a connecting part 32 fixed to the machine inner side of the main body part 31, and a reinforcing part 33 that is a drive collar attached to the end face of the connecting part 32 on the machine inner side. Yes.

An end surface on the machine outside of the main body 31 is a rotation-side sealed end surface 31a. The connecting portion 32 is movable in the axial direction together with the main body portion 31 and the reinforcing portion 33 in a state where the inner peripheral surface on the inside of the machine is sealed (secondary seal) by the O-ring 12 with respect to the outer peripheral surface of the rotary shaft 60. Is held in.
A drive pin 13 protruding to the inside of the machine is fixed to the connecting portion 32, and the drive pin 13 is engaged with an engagement hole 33 a formed in the reinforcing portion 33. This prevents the reinforcing portion 33 from rotating relative to the main body portion 31 and the connecting portion 32.

  The elastic member 4 is made of, for example, a compression coil spring and is held by the retainer 2. The end of the elastic member 4 on the outside of the machine is in contact with the end surface of the reinforcing part 33 on the inside of the machine, and the urging force of the elastic member 4 biases the rotary seal ring 3 toward the outside of the machine in the axial direction. Thereby, the rotation-side sealing end surface 31 a of the rotation sealing ring 3 is pressed against a stationary-side sealing end surface 6 a described later by the urging force of the elastic member 4.

The mechanical seal 1 includes, as a stationary side unit, an annular stationary sealing ring 6 fitted in the casing 50, and a seal portion 9 that seals between the inner periphery of the casing 50 and the outer periphery of the stationary sealing ring 6. Yes.
The end of the stationary seal ring 6 on the outside of the machine is prevented from rotating relative to the casing 50 by a pin 14 protruding from the casing 50 to the inside of the machine. At the end of the stationary seal ring 6 on the inside of the machine, a stationary side seal end face 6a is formed in which the rotary side seal end face 31a of the rotary seal ring 3 is in sliding contact.

An annular seal surface (first seal surface) 52 c extending in the radial direction is formed on the inner peripheral portion of the casing 50. An annular seal surface (second seal surface) 6 f that is opposed to the seal surface 52 c of the casing 50 in the axial direction is formed on the outer side of the outer peripheral portion of the stationary seal ring 6.
The seal portion 9 seals between the seal surface 52 c of the casing 50 and the seal surface 6 f of the stationary seal ring 6. The seal portion 9 includes a rubber O-ring 9a and an annular gasket 9b made of a material having thermal conductivity and disposed outside the O-ring 9a in the radial direction.

The O-ring 9a is formed in an elliptical cross section, and its axial dimension is set longer than the axial dimension of the gasket 9b. Thereby, the crushing margin of the O-ring 9a is set larger than the crushing margin of the gasket 9b.
One side surface 9b1 in the axial direction of the gasket 9b is in direct surface contact with the sealing surface 52c of the casing 50. Further, the other axial side surface 9 b 2 of the gasket 9 b is in direct surface contact with the sealing surface 6 f of the stationary sealing ring 6. In addition, the point which abbreviate | omitted description in 2nd Embodiment is the same as that of 1st Embodiment.

  Also in the mechanical seal 1 of the present embodiment configured as described above, the seal portion 9 includes the rubber O-ring 9a, so that the sealing performance between the first seal surface 52c and the second seal surface 6f is improved. Can be secured. Further, since the seal portion 9 has a metal gasket 9b disposed on the outer side in the radial direction of the O-ring 9a, heat such as sliding heat generated in the stationary seal ring 6 is transferred to the casing 50 side via the gasket 9b. Heat can be radiated efficiently. Therefore, the heat dissipation performance from the stationary seal ring 6 to the casing 50 can be enhanced without reducing the sealing performance.

Further, since the gasket 9b is arranged on the outer side in the radial direction of the O-ring 9a, the seal portion 9 can be easily assembled as compared with the case where the gasket 9b is arranged on the inner side in the radial direction of the O-ring 9a.
Further, since both side surfaces 9b1 and 9b2 in the axial direction of the gasket 9b are in direct surface contact with the first seal surface 52c on the casing 50 side and the second seal surface 6f of the stationary seal ring 6, respectively, the stationary seal ring 6 The generated sliding heat or the like can be radiated more efficiently to the casing 50 side via the gasket 9b.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the seal portion in the above embodiment, the gasket is disposed on the radially outer side of the O-ring, but the gasket may be disposed on the radially inner side of the O-ring. In addition, the gasket in the above embodiment is in direct surface contact with the first and second seal surfaces, but may be in direct surface contact with either one of the seal surfaces or indirectly with both seal surfaces. It may be.

DESCRIPTION OF SYMBOLS 1 Mechanical seal 3 Rotating seal ring 6 Static seal ring 6d-6f Seal surface (2nd seal surface)
7-9 Seal portion 7a-9a O-ring 7b-9b Gasket 7b1-9b1 One side 7b2-9b2 Other side 50 Casing 51b Seal surface (first seal surface)
52b Seal surface (first seal surface)
52c Seal surface (first seal surface)
60 axis of rotation

Claims (2)

A mechanical seal comprising: a rotary seal ring attached to the rotary shaft so as to be integrally rotatable; and a stationary seal ring fixed to a casing side surrounding the rotary shaft and in sliding contact with the rotary seal ring,
It said to be opposite to the first sealing surface of the annular formed extending in Oite radially inner periphery of the casing side, in the axial direction of the rotary shaft across the annular space for the first sealing surface A seal portion that seals between the annular second seal surface formed on the outer periphery of the stationary seal ring;
The seal portion includes a comprising: a rubber O-ring disposed in said annular space, and a ring-shaped gasket having disposed thermally conductive radially outer side of the O-ring in said annular space Mechanical seal. Mechanical seal according to claim 1 which before direct contact faces one side in the axial direction of the outs basket within the first sealing surface, the other side of the axial direction of the gasket is in direct contact surface with the second sealing surface.

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