JP2011058517A - Dry contact mechanical seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry contact mechanical seal effectively suppressing heat generation and rise of temperature of a static sealing ring to demonstrate a good mechanical seal function. <P>SOLUTION: The dry contact mechanical seal seals an internal gas area A and an external gas area B by relative rotation slid-contact action between a rotary sealing ring and the static sealing ring 3. The rotary sealing ring 5 is held to be axially movable by a rotational shaft 4, and the static sealing ring 3 is fitted and fixed to an inner peripheral face of a metallic seal case 2 through a pair of O-rings 8, 9. An annular space 14 sealed with the O-rings 8, 9 is formed between opposed peripheral faces of the seal case 2 and the static sealing ring 3. The annular space 14 is filled with and encloses heat medium oil (such as silicone oil and grease) 15 higher in heat expansion coefficient than air, and heat generated in the static sealing ring 3 by slide-contact with the rotary sealing ring 5 is radiated to the seal case 2 through the heat medium oil 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dry contact mechanical seal equipped as a shaft seal device in a rotating device such as a stirrer that handles gas.

  As a conventional dry contact mechanical seal, a rotary seal ring held axially movable on a rotary shaft and a stationary seal ring fitted and fixed to the inner peripheral surface of a metal seal case via a pair of O-rings It is well known that it is configured to seal the in-machine gas region and the out-of-machine gas region (atmosphere region) by the relative rotational sliding action.

  In such a dry contact mechanical seal, since the relative rotational sliding contact portions of both sealing rings are operated in a dry atmosphere (gas atmosphere) in which liquid lubrication is not performed, the sliding contact surfaces (sealing end surfaces) of both sealing rings are used. Generates frictional heat. Thus, since the rotating seal ring is rotated by the rotating shaft, the generated heat is effectively dissipated by the rotating action (a kind of air cooling action). However, since the stationary seal ring is stationary in the gas region, the heat generated by friction with the rotating seal ring is stored without being dissipated. There is a possibility that a good mechanical seal function cannot be exhibited, such as a large amount of leakage due to abnormal wear or deformation of the sealed end face due to thermal strain. By the way, the seal case that fits and holds the stationary seal ring is made of a metal material having high thermal conductivity. However, the assembly of the mechanical seal between the stationary seal ring and the seal case causes the pair of O Since a space closed by the ring is inevitably formed, that is, an air layer with low thermal conductivity is formed between the stationary sealing ring and the sealing case, the stationary sealing ring to the sealing case is formed. Heat dissipation cannot be expected. Since an O-ring made of a rubber material having a higher thermal conductivity than air is interposed between the stationary seal ring and the seal case, the stationary seal ring is passed through the O-ring to the seal case. However, since the contact area (heat dissipating area) between the O-ring and the stationary sealing ring and the seal case is very small, the effect of heat dissipation via the O-ring can hardly be expected.

  Conventionally, in order to prevent and avoid such heat generation and temperature rise of the stationary seal ring, an annular cooling space sealed with the pair of O-rings is formed between the stationary seal ring and the seal case. It has been proposed to circulate and supply cooling water to this (see, for example, FIG. 2 of Patent Document 1).

Japanese Utility Model Publication No. 2-98271

  However, when such a circulating supply of cooling water is performed, the equipment required for this is required separately, so the mechanical seal configuration becomes larger and more complicated than necessary, and the initial cost and running cost also rise. There's a problem.

  The present invention provides a dry contact mechanical seal that can effectively suppress the heat generation and temperature rise of the stationary seal ring without causing such problems, and can exhibit a good mechanical seal function. It is the purpose.

  The present invention relates to a relative rotational sliding contact between a rotary seal ring held axially movable on a rotary shaft and a stationary seal ring fitted and fixed to an inner peripheral surface of a metal seal case via a pair of O-rings. In the dry contact mechanical seal configured to seal the in-machine gas region and the out-of-machine gas region by the action, in order to achieve the above-described object, in particular, between the opposed peripheral surfaces of the seal case and the stationary seal ring, the pair An annular space sealed with an O-ring is formed, and the annular space is filled and filled with a heat medium having fluidity and a higher thermal expansion coefficient than air, so that the stationary sealing ring is brought into sliding contact with the rotary sealing ring. It is proposed that the heat generated in the heat sink is radiated to the seal case through the heat medium. In such a dry contact mechanical seal, it is preferable that the stationary sealing ring is fitted and fixed to the inner peripheral surface of the seal case via the pair of O-rings in a non-contact state. As the heat medium, water having fluidity and a coefficient of thermal expansion higher than that of air can be used. Generally, heat medium oil (silicon oil, grease, etc.) having stability against heating and non-volatility is used. ) Is best used.

  In the dry contact mechanical seal of the present invention, since a heat medium (heat medium oil or the like) is interposed between the seal case and the stationary seal ring, the metal is made from the stationary seal ring through the heat medium. Heat is dissipated to the seal case, heat generated by friction is not stored in the stationary seal ring, and thermal distortion does not occur and the stationary seal ring and its sealed end face are not deformed. Therefore, according to the present invention, there is provided a dry contact mechanical seal that can effectively perform the heat dissipation action of the stationary seal ring without requiring a cooling water circulation supply facility and the like, and can exhibit a mechanical seal function well. can do.

FIG. 1 is a longitudinal front view showing an example of a dry contact mechanical seal according to the present invention. FIG. 2 is a longitudinal side view of the mechanical seal. FIG. 3 is an enlarged detailed view showing a main part of FIG.

  Embodiments of the present invention will be specifically described below with reference to FIGS. FIG. 1 is a longitudinal front view showing an example of a dry contact mechanical seal according to the present invention, FIG. 2 is a longitudinal side view of the mechanical seal, and FIG. 3 is an enlarged detailed view showing the main part of FIG. .

  The dry contact mechanical seal in this embodiment is used as a shaft sealing means of a vertical rotating device (such as a stirrer), and is configured as follows according to the present invention. In the following description, the top and bottom mean the top and bottom in FIGS.

  That is, in the dry contact mechanical seal, as shown in FIGS. 1 and 2, the seal case 2 is attached to the shaft seal portion 1 a that is the upper end portion of the housing 1 of the rotating device, and the stationary seal ring 3 is fixed to the seal case 2. The rotary seal ring 5 is fitted and held on the rotary shaft (stirring shaft or the like) 4 of the rotating device concentrically penetrating the stationary seal ring 3 through the O-ring 6 so as to be movable in the axial direction. The spring member 7 (see FIG. 2) interposed between this and the rotating shaft 4 is pressed and urged to the stationary sealing ring 3, and the relative rotation of the sealing end faces 3a and 5a, which are the opposite end faces of the both sealing rings 3 and 5, is achieved. The sliding contact action is configured to shield and seal the in-machine gas region A that is the inner peripheral side region of the relative rotational sliding contact portion and the out-of-machine gas region B that is the outer peripheral side region. In this example, the out-of-machine gas region B is an atmospheric region, and the in-machine gas region A is a positive pressure gas region having a higher pressure than the atmospheric region B or a negative pressure gas region (for example, a vacuum region) having a lower pressure than the atmospheric region B. is there.

  As shown in FIGS. 1 and 2, the seal case 2 is a cylindrical body attached to the housing 1 so as to abut against the shaft seal portion 1a, and is made of a metal material such as stainless steel (for example, SUS304). ing.

  As shown in FIGS. 1 and 2, the stationary sealing ring 3 is made of an appropriate material selected according to the sealing conditions (carbon, ceramics such as silicon carbide, composite material mainly composed of polytetrafluoroethylene (PTFE), An annular body made of cemented carbide or the like, and is concentrically fitted and fixed to the inner peripheral portion of the seal case 2 via a pair of upper and lower O-rings 8 and 9. The upper end surface, which is the distal end surface of the stationary seal ring 3, is configured as a sealed end surface (hereinafter referred to as "stationary side sealed end surface") 3a which is an annular smooth plane orthogonal to the axis. In addition, the lower end side inner peripheral surface of the stationary seal ring 3 is a conical surface 3b that expands downward.

  The rotary shaft 4 extends vertically from the shaft seal portion 1a and passes through the seal case 2 and the stationary seal ring 3 concentrically. As shown in FIGS. A spring retainer 10 made of a metal material such as stainless steel (for example, SUS316 or the like) is fitted and fixed above the ring 3. This spring retainer 10 is a cylindrical body having an L-shaped cross section comprising a cylindrical sealing ring holding portion 10a and a large-diameter annular spring holding portion 10b integrally formed at the upper end thereof. The screw 11 is fixed to the rotating shaft 4.

  As shown in FIGS. 1 and 2, the rotary seal ring 5 includes a main body portion 5b and a secondary seal portion 5c formed integrally with the base end (upper end), and a base seal surface (upper end surface) and a secondary seal portion 5c. It is constituted by an annular body composed of a reinforcing portion 5d fitted and fixed in a state of being brought into contact with the outer peripheral surface, and an O-ring 6 is interposed between the secondary seal portion 5c and the rotating shaft 4. In the next sealed state, the rotary shaft 4 is fitted and held so as to be movable in the axial direction. The main body portion 5b and the secondary seal portion 5c are an integral structure, and an appropriate material (ceramics such as carbon and silicon carbide, polytetrafluoroethylene (PTFE)) as a main component is selected according to the constituent material of the stationary seal ring 3 The lower end surface, which is the front end surface of the main body portion 5b, is a sealed end surface that is an annular smooth plane orthogonal to the axis (hereinafter referred to as "rotation side sealed end surface"). 5a. The reinforcing portion 5d is a drive collar made of a metal material such as stainless steel (for example, SUS316), and the drive pin 12 fixed thereto is formed at the base end portion of the secondary seal portion 5c of the rotary seal ring 5. By engaging with the engagement hole 5e, relative rotation between the main body 5b and the secondary seal 5c is prevented. A drive pin 13 inserted through a through hole 10c formed in the spring holding portion 10b of the spring retainer 10 is fixed to the reinforcing portion 5d, and the rotary seal ring 5 is allowed to move in the axial direction within a predetermined range. Thus, the rotation relative to the rotation shaft 4 is impossible. Further, the axial movement of the O-ring 6 is caused by the front end surface of the sealing ring holding portion 10a of the spring retainer 10 that has entered the inner peripheral portion of the secondary seal portion 5c and the main body portion 5b of the rotary sealing ring 5 facing this. Locking is restricted by the inner peripheral base end face.

  As shown in FIG. 2, the spring member 7 is composed of a plurality of coil springs 7a loaded at equal intervals in the circumferential direction between the reinforcing portion 5d of the rotary seal ring 5 and the spring holding portion 10b of the spring retainer 10. The rotary seal ring 5 is pressed and urged to the stationary seal ring 3.

  Thus, in the dry contact mechanical seal configured as described above, the heat generated in the stationary seal ring 3 (friction heat due to sliding contact with the rotary seal ring 5) is effectively radiated according to the present invention. Therefore, the following measures are taken.

  That is, an annular space 14 sealed with O-rings 8 and 9 is formed between the opposed peripheral surfaces of the seal case 2 and the stationary seal ring 3 fitted and held therein, as shown in FIGS. The annular space 14 is filled with a heat medium 15 having fluidity and a thermal expansion coefficient higher than that of air. In this example, heat medium oil is used as the heat medium 15. The O-rings 8 and 9 are annular protrusions projecting at the center of the outer peripheral surface of the stationary seal ring 3 between both ends of the outer peripheral surface of the stationary seal ring 3 and both ends of the inner peripheral surface of the seal case 2. 3c and an annular protrusion 2a protruding from the upper end of the inner peripheral surface of the seal case 2 and an annular protrusion 1b protruding from the housing 1 are loaded in a state where displacement in the axial direction is restricted. The annular space 14 is formed by forming an annular recess facing the annular protrusion 3 c on the inner peripheral surface of the seal case 2, and is sealed by O-rings 8 and 9. Needless to say, the annular space 14 is larger than what is inevitably produced in the mechanical seal assembly as described at the beginning. As shown in FIG. 3, the stationary seal ring 3 and the seal case 2 (and the housing 1) are in indirect contact with each other via the O-rings 8 and 9, and are not completely in direct contact with each other. It is in a state. That is, the inner peripheral surface (including the annular protrusion 2 a) of the seal case 2 is not in contact with the outer peripheral surface (including the annular protrusion 3 c) of the stationary seal ring 3, and the annular protrusion 1 b of the housing 1 is not in contact with the seal case 2. However, the stationary sealing ring 3 is not in contact with the stationary sealing ring 3.

  Filling and enclosing the heat medium oil 15 in the annular space 14 is performed, for example, as follows. That is, as shown in FIG. 1, a heat medium oil supply hole 16 penetrating from the outer peripheral portion to the annular space 14 is formed in the seal case 2, and the heat medium oil 15 is transferred from the heat medium oil supply hole 16 to the annular space 14. Supply. Then, after the heat medium oil 15 is filled in the annular space 14, the opening of the heat medium oil supply hole 16 is closed with an appropriate plug (mekura plug, mekra lid) 17. In addition, when filling the heat medium oil 15, it is necessary to completely exclude the air from the annular space 14. In order to completely replace the air in the annular space 14 with the heat medium oil 15, For example, it is preferable to form an air vent hole 18 opening upward from the annular space 14 in the seal case 2 as shown by a chain line in FIG.

  The heat medium oil 15 can be arbitrarily used as long as it is oil-based (having fluidity such as liquid) having a thermal conductivity higher than that of air, but it has a melting point or boiling point depending on the sealing conditions. The temperature range of the liquid phase is wide, the heat capacity per unit volume is large (specific heat is large), and the contact member (seal case 2, O-rings 8, 9 etc.) is not corroded. It is preferable to use one that satisfies the conditions of being harmless to the environment and the human body. In this example, silicone oil and grease satisfying all such conditions and economically advantageous are used.

  In the dry contact mechanical seal constructed as described above, when frictional heat is generated by sliding contact between the sealing rings 3 and 5, the rotating sealing ring 5 rotates as described at the beginning. It is cooled by a kind of air cooling action. On the other hand, the stationary seal ring 3 that is stationary without rotating is not cooled by the self-rotation unlike the rotary seal ring 5, but the generated heat is transferred from the stationary seal ring 5 through the heat medium oil 15 to the metal. Heat is radiated to the seal case 2 made of metal. That is, even when frictional heat is generated in the stationary seal ring 3 due to sliding contact with the rotary seal ring 5, an air layer having a low thermal conductivity is formed between the seal case 2 and the conventional seal. In contrast, the frictional heat is quickly radiated to the metal seal case through the heat medium oil 15, so that the heat is not stored in the stationary seal ring 3, and the sealed end face 3 a of the stationary seal ring 3. Thus, it is possible to effectively prevent heat distortion from occurring and deformation of the stationary seal ring 3 due to high temperature. As a result, even when the contact region of the stationary seal ring 3 is operated in a dry atmosphere where the gas regions A and B are in a dry atmosphere (dry operation), the relative rotational sliding contact between the sealed end faces 3a and 5a of both the seal rings 3 and 5 is achieved. The mechanical seal function is excellent.

  In addition, since the seal case 2 made of different materials having different thermal expansion coefficients and the stationary seal ring 3 are in a non-contact state through only the O-rings 8 and 9 and the heat medium oil 15, Mutual interference due to the difference in thermal expansion does not occur, and the stationary sealing ring 3 is not deformed by thermal deformation of the seal case 2.

  The configuration of the present invention is not limited to the above-described embodiment, and can be appropriately improved and modified without departing from the basic principle of the present invention. For example, in the example described above, the present invention is applied to a dry contact mechanical seal that is installed in a vertical rotating device whose rotating shaft extends in the vertical direction. However, the present invention is installed in a horizontal rotating device in which the rotating shaft extends horizontally. The present invention can also be suitably applied to dry contact mechanical seals. Moreover, although it is preferable to use the above-described heat medium oil as the heat medium 15, water or the like can be used depending on the sealing conditions.

DESCRIPTION OF SYMBOLS 1 Housing of rotating equipment 1a Shaft sealing part 2 Seal case 3 Static sealing ring 3a Sealing end surface of stationary sealing ring 4 Rotating shaft 5 Rotating sealing ring 5a Sealing end surface of rotating sealing ring 8 O ring 9 O ring 14 Annular space 15 Heat medium oil (Heat medium)
A In-machine gas area B Out-of-machine gas area

Claims (4)

In-machine gas due to relative rotational sliding contact between a rotary seal ring held axially movable on the rotary shaft and a stationary seal ring fitted and fixed to the inner peripheral surface of a metal seal case via a pair of O-rings In a dry contact mechanical seal configured to seal an area and an off-board gas area,
An annular space sealed with the pair of O-rings is formed between the opposed peripheral surfaces of the seal case and the stationary seal ring, and the annular space is filled with a heat medium having fluidity and a higher thermal expansion coefficient than air. A dry contact mechanical seal characterized in that heat generated in the stationary seal ring by sliding contact with the rotary seal ring is radiated to the seal case through the heat medium.   The dry contact mechanical seal according to claim 1, wherein a stationary seal ring is fitted and fixed to the inner peripheral surface of the seal case via the pair of O-rings in a non-contact state.   The dry contact mechanical seal according to claim 1 or 2, wherein the heat medium is a heat medium oil.   The dry contact mechanical seal according to claim 3, wherein the heat medium oil is silicone oil / grease.