JP4797090B2 - Double mechanical seal - Google Patents

Description

  The present invention relates to a double mechanical seal having a process-side first mechanical seal formed over a rotating shaft and a housing, and an atmosphere-side second mechanical seal formed over the rotating shaft and the housing. It is.

  This type of double mechanical seal is used in places where leakage conditions are severe, and requires a larger arrangement space than a single mechanical seal, but two sets of mechanical seals prevent leakage almost completely. There are advantages that can be made. It is a suitable seal when the liquid to be sealed used on the process side is liable to adversely affect the environment when asphalt, naphtha or the like leaks.

  As the first mechanical seal on the process side, in order to seal the liquid to be sealed with a simple structure, the structure to press and urge the stationary seal ring supported on the housing side against the rotating seal ring by an elastic mechanism is used. It is advantageous to configure the elastic mechanism with a bellows so as to effectively prevent liquid from entering from the stationary seal ring side. As an example of a mechanical seal having such a structure, one disclosed in Patent Document 1 is known.

  Therefore, in order to obtain a high-performance sealing performance, when a double mechanical seal having a structure having a first mechanical seal having a bellows is newly designed, the conventional configuration shown in Patent Document 1 has a problem in some cases. There is a place that is predicted. It is a configuration around the stationary sealing ring of the first mechanical seal. That is, as shown in FIG. 5, the annular stationary sealing ring 37 is integrated by shrink fitting into the retainer 38 that receives the force of the bellows 6, so that the outer peripheral surface 37 b of the stationary sealing ring 37 and the retainer 38 are integrated. The outer peripheral surface 37c of the stationary sealing ring 37 and the inner peripheral surface 38e of the stationary sealing ring side of the retainer 38 are merely brought into contact with each other. There is a gap between them 37c and 38e.

  That is, it is in a state capable of functioning as a hydraulic cylinder Ck in which the gap between the retainer side outer peripheral surface 37c of the stationary seal ring 37 and the stationary seal ring side inner end peripheral surface 38e of the retainer 38 is a cylinder chamber. If the pressure of the seal liquid e supplied to the seal portion S, which is a portion where the stationary seal ring 37 and the rotary seal ring (not shown) contact through the inside of the seal 6 is high to a certain degree, the stationary fit is performed. There is a disadvantage that the sealing ring 37 may be pushed out from the retainer 38 in the axial direction.

JP 11-013894 A

  An object of the present invention is to newly design a double mechanical seal having a first mechanical seal in which a stationary seal ring pressed and urged by a bellows is shrink-fitted into a retainer. The point is that the stationary sealing ring can be provided in an improved state so as to avoid the disadvantage of being pushed out of the retainer.

According to the first aspect of the present invention, the first mechanical seal M1 on the process side configured across the rotary shaft 1 and the housing 2, and the first on the atmosphere side configured across the rotary shaft and the housing 2 are provided. In a double mechanical seal having two mechanical seals M2,
The first mechanical seal M1 is supported on the housing side so as to be able to move in the direction of the axis P of the rotary shaft 1 and the rotary seal ring 5 that rotates integrally with the rotary shaft 1, and the axis P A stationary seal ring 7 fitted to an annular retainer 8 that is pressed and urged against the rotary seal ring 5 in the direction of the axis P by the bellows 6 made of an elastic material around the center, and a process liquid t on the process side A seal liquid supply passage 16 formed in the housing 2 for supplying the high-pressure seal liquid e to the seal portion S1 where the rotary seal ring 5 and the stationary seal ring 7 are in contact with each other through the inside of the bellows 6; It is configured as
The retainer 8 is formed to have an outer peripheral portion 8a into which the stationary seal ring 7 is tightly fitted, and a flange portion 8b extending radially inward from the outer peripheral portion 8a to receive the bellows 6. In addition, an O-ring 3 that seals the gap 14 with a diameter X that is equal to or less than the effective diameter F of the bellows 6 is provided in the gap 14 in the axial center P direction between the stationary seal ring 7 and the flange 8b. It is characterized by being.

  The invention according to claim 2 is characterized in that, in the double mechanical seal according to claim 1, a snap ring 9 is mounted on the inner diameter side of the O-ring 3 in the gap portion 14.

  The invention according to claim 3 is the double mechanical seal according to claim 1 or 2, wherein the baffle cylinder is integrated with the housing 2 while being loosely fitted to the rotary shaft 1 inside the bellows 6. 13 is provided, and the sealing liquid e supplied from the sealing liquid supply path 16 is configured to be guided to the sealing portion through the outer diameter of the baffle cylinder 13. It is.

  According to a fourth aspect of the present invention, in the double mechanical seal according to the third aspect, the seal liquid e guided to the seal portion S1 passes between the baffle cylinder 13 and the rotary shaft 1 and the second mechanical seal. The housing 2 and the baffle cylinder 13 are shaped so that the rotary seal ring 23 and the stationary seal ring 24 in the mechanical seal M2 are supplied to the seal portion S2. .

  According to the first aspect of the present invention, the maximum diameter of the hydraulic cylinder that will function as a cylinder chamber when the O-ring is loaded in the gap portion will be described in detail in the section of the embodiment. Since the effective seal diameter of the O-ring can be achieved, the maximum diameter of the hydraulic cylinder can be made smaller than the effective diameter of the bellows. As a result, even when a sealing liquid having a pressure higher than that of the process liquid is supplied, the pressing force by the hydraulic cylinder is weaker than the pressing force by the effective diameter of the bellows, and the stationary sealing ring is not pulled out from the retainer. As a result, in newly designing a double mechanical seal having a first mechanical seal in which a stationary seal ring pressed and urged by a bellows is shrink-fitted into the retainer, depending on the pressure of the seal liquid, Can be provided as an improvement in which the disadvantage of being extruded from the retainer is avoided.

  According to the invention of claim 2, this will also be described in the section of the embodiment, but by providing an O-ring in the gap, a stationary sealing ring, a retainer and an O-ring are provided on the outer peripheral side of the O-ring in the gap. A sealed portion surrounded by the three is formed. The air present in the sealed portion may expand in volume due to the temperature rise of the device accompanying the operation of the double mechanical seal, and the pressure may cause the O-ring to dig out to the inside of the diameter. Therefore, by arranging the snap ring inside the diameter of the O-ring, it is possible to prevent the O-ring from protruding into the diameter inside and maintain a good contact pressure of the seal portion. That is, a new inconvenience caused by the configuration in which the O-ring is provided in the gap can be solved.

  According to the invention of claim 3, the baffle tube provided between the rotating shaft and the bellows in the radial direction functions as a guide member for the seal liquid, and smoothly guides the seal liquid to the seal portion of the first mechanical seal, The seal portion can be efficiently lubricated and cooled.

  According to the invention of claim 4, the cylindrical passage provided between the baffle cylinder and the rotary shaft in the radial direction is smooth and efficient without causing the sealing liquid passing through the seal portion of the first mechanical seal to be swollen. There is an advantage that it can be moved toward two mechanical seals.

Cross-sectional view of the entire double mechanical seal (Example 1) Expanded sectional view of the main part of the first mechanical seal Enlarged sectional view of the main part showing the fitting structure part of the stationary seal ring and retainer Dimensional drawing of parts related to stationary seal ring Configuration dimensions of conventional stationary seal ring related parts

  Embodiments of a double mechanical seal according to the present invention will be described below with reference to the drawings.

[Example 1]
As shown in FIG. 1, the double mechanical seal A according to the first embodiment includes a process-side (inner side) first mechanical seal M <b> 1 configured between the rotary shaft 1 and the housing 2, the rotary shaft 1, and the housing 2. And a second mechanical seal M2 on the atmosphere side (outside). The housing 2 that surrounds the rotating shaft 1 includes a main case portion 2A in which a sealing liquid supply passage 16 is formed and a cover case portion 2B in which a sealing liquid outlet passage 17 is formed. The rotation shaft 1 is provided with a rotation support portion 4 that is engaged with the process-side shaft portion 1a and rotates integrally therewith.

  The function of the double mechanical seal A will be briefly described. In the double mechanical seal A, the high-pressure seal liquid e entering from the seal liquid supply passage 16 is supplied to the first seal portion S1 of the first mechanical seal M1, and then passes through the outer peripheral portion of the rotary shaft 1 to the second mechanical seal A. 2 It is filled with the state led to the seal part S2 of the mechanical seal M2 and then discharged from the seal liquid outlet passage 17. The sealing target t such as asphalt or naphtha on the process side is securely sealed by the first mechanical seal M1 using the sealing liquid e higher in pressure than the sealing target t, and the sealing liquid e is sealed by the second mechanical seal M2. Sealed against the atmosphere side. Therefore, even if the sealing liquid e may slightly leak to the atmosphere side or the process side, the sealing target t does not leak to the atmosphere side.

  Now, the first mechanical seal M1 located on the process side is supported on the housing 2 side so that the first rotary seal ring 5 that rotates integrally with the rotary shaft 1 and the axis P of the rotary shaft 1 can be moved, And a first stationary seal ring 7 fitted to an annular retainer 8 pressed and urged against the first rotary seal ring 5 in the direction of the axis P by the bellows 6 made of an elastic material centered on the axis P, and the process A seal liquid e higher in pressure than the process liquid on the side passes through the inside of the bellows 6 and is supplied to the first seal portion S1 formed by contact between the seal surface 5a of the first rotary seal ring 5 and the seal surface 7a of the first stationary seal ring 7. The seal liquid supply path 16 formed in the housing 2 is preferably configured.

  The rotation support unit 4 includes a base rotation ring body 4A that is occluded and fitted to the process side shaft portion 1a, a support rotation body 4B that is laterally mounted in the direction of the axis P and has an O-ring 10 with respect to the rotation shaft 1, and The lid ring body 4C is laterally mounted in the direction of the axis P, and the lid ring body 4C and the support rotating body 4B are bolted to the base rotating ring body 4A in a fastened state. The first rotating seal ring 5 made of SiC is externally fitted to the support rotating body 4B via the O-ring 11, and the presence of the cover ring body 4C is prevented from coming out from the support rotating body 4B in the axis P direction. ing. In addition, if the cover ring body 4C is removed from the support rotation body 4B, the 1st rotation sealing ring 5 can be extracted from the support rotation body 4B.

  As shown in FIGS. 1 and 2, the first stationary seal ring 7 made of tungsten carbide is tightly fitted into and integrated with the retainer 8 by shrink fitting, and a flange portion 8 a that is a side peripheral wall of the retainer 8. Made of Inconel (trade name of nickel alloy containing chromium, iron, silicon, etc. and an example of an elastic material) over the side peripheral surface 12a of the adapter 12 fitted and supported on the process side of the main case 2A. A bellows 6 is installed. Further, the baffle tube 13 is even fitted and supported on the atmosphere side of the main case portion 2A so as to be loosely fitted to the rotary shaft 1 and loosely fitted to the adapter 12. The retainer 8 is externally fitted to the baffle cylinder 13 so as to be movable in the axial center P direction, and a path is formed between the retainer 8 and the baffle cylinder 13 so that fluid can move in the axial center P direction. .

  The seal liquid e is taken into the outer peripheral side of the baffle cylinder 13 from the seal liquid supply path 16 of the rotation support portion 4, and between the baffle cylinder 13 and the adapter 12, the bellows 6, the retainer 8, and the first stationary seal ring 7. The annular passage flows in the direction from the second mechanical seal M2 side toward the first mechanical seal M1 side, and is supplied to the first seal portion S1. The seal liquid e that has passed through the first seal portion S1 flows in the direction from the first mechanical seal M1 side to the second mechanical seal M2 side through the annular passage between the baffle cylinder 13 and the rotary shaft 1, and the second mechanical seal M2 After flowing from the inner diameter side to the outer diameter side between the back surface of the spring retainer 15 and the side peripheral end surface 13a of the baffle cylinder 13, the first annular passage is formed between the second elastic mechanism 18 and the cover case portion 2B. It flows in a direction from the mechanical seal M1 side toward the second mechanical seal M2 side. Then, after the sealing liquid e is supplied to the second seal part S2, it is discharged to the outside from the sealing liquid outlet path 17 of the cover case part 2B.

  That is, the baffle cylinder 13 integrated with the housing 2 while being loosely fitted to the rotary shaft 1 inside the bellows 6 is provided, and the seal liquid e supplied from the seal liquid supply path 16 is baffled. The tube 13 is configured to be guided to the first seal portion S <b> 1 through the outside of the diameter of the tube 13. Then, the seal liquid e guided to the first seal portion S1 passes between the baffle cylinder 13 and the rotary shaft 1, and the second rotary seal ring 23 and the second stationary seal ring 24 in the second mechanical seal M2 are formed. The shape of the housing 2 and the baffle cylinder 13 is set so as to be supplied to the second seal portion S2 that comes into contact therewith.

  Accordingly, the seal liquid e is guided to the baffle cylinder 13 by the adapter 12, the bellows 6, the retainer 8, and the annular outward path 25 formed between the first stationary seal ring 7 and the baffle cylinder 13 in the radial direction. It is possible to promote reaching the one seal portion S1, and the first seal portion S1 can be efficiently lubricated and cooled. And, it becomes possible to smoothly guide the seal liquid e having passed through the first seal portion S1 to the second mechanical seal M2 by an annular return path 26 formed between the baffle cylinder 13 and the rotary shaft 1 in the radial direction. . The sealing liquid e from the return path 26 flows to the outside of the diameter of the back surface of the spring retainer 15 and then is formed between the elastic mechanism 18 formed on the rotary shaft 1 and the cover case portion 2B in the radial direction. After proceeding through the introduction path 27, the second seal portion S2 is efficiently lubricated and cooled, and then discharged from the seal liquid outlet path 17.

  As shown in FIGS. 3 and 4, the retainer 8 includes an outer peripheral portion 8 b in which the first stationary sealing ring 7 is tightly fitted, and a flange portion extending radially inward from the outer peripheral portion 8 b to receive the bellows 6. 8a and is formed in a ring having a substantially L-shaped cross section. An internal O-ring 3 that seals the gap 14 with a diameter equal to or less than the effective diameter F of the bellows 6 is provided in the gap 14 in the axial center P direction between the first stationary seal ring 7 and the flange 8 a.

  The first stationary seal ring 7 is formed in a tapered shape in which the radially inner side and the radially outer side of the seal surface 7a are cut obliquely. The outer peripheral surface 7b and the inner peripheral surface 8c of the outer peripheral portion 8b are liquid-fitted by shrink fitting. Closely fitted. The flange portion 8a is a projecting end peripheral surface 8d capable of contacting the outer peripheral side of the atmosphere-side end peripheral surface 7c of the first stationary seal ring 7, and a surface separated from the atmosphere-side end peripheral surface 7c in the axis P direction. An inner end peripheral surface 8e is formed, and an annular space between the atmosphere-side end peripheral surface 7c and the inner end peripheral surface 8e is formed in the gap portion 14. An interior O-ring 3 is provided on the outer diameter side of the gap 14, and a snap ring 9 is fitted on the inner diameter side.

  The effective seal diameter X of the interior O-ring 3 that is in contact with the step inner circumferential surface 8 f that is the maximum diameter of the gap portion 14 is configured to be smaller than the effective diameter F of the bellows 6. Further, the snap ring 9 is fitted exactly inside the interior O-ring 3. In this way, the retainer 3 is formed as a resilient shape, the gap 14 is intentionally formed, and the interior O-ring 3 and the snap ring 9 are loaded for the following reason.

  In the conventional mechanical seal, as shown in FIG. 5, since the stationary sealing ring 37 is merely shrink-fitted to the retainer 38, there is a gap between the atmosphere side end surface 37c and the inner end surface 38e. As a result, a cylinder chamber having a diameter D corresponding to the outer diameter of the stationary sealing ring 37 is formed. Since the seal surface 37a of the stationary seal ring 37 is tapered and has a cross-sectional shape, the maximum diameter of the portion where the seal liquid e exists in the seal portion S is the diameter E, and the minimum diameter of the portion where the process liquid t exists is If the effective diameter of the bellows 6 is the diameter F, the diameter D> the diameter G> the diameter F> the diameter E.

  Thus, when the sealing liquid e having a pressure higher than that of the process liquid t is supplied and enters the cylinder chamber, it functions as a hydraulic cylinder Ck having a diameter D with the stationary sealing ring 37 as a piston. The pressing force due to the seal liquid e acting on the area between the diameter D and the diameter F is larger than the resultant force of the pressing force due to the area acting between the diameter F and the pressing force due to the bellows 6. You may win. In this case, the retainer 38 and the stationary seal ring 37 are separated from each other in the direction of the axis P, and as a result, the stationary seal ring 37 may be pushed out of the retainer 38.

  3 and FIG. 4, the present invention is the same in that the first stationary seal ring 7 is shrink-fitted to the retainer 8 as shown in FIGS. The flange 8b of the retainer 8 is intentionally stepped so that a clear gap 14 is formed between the two, and the interior O-ring 3 is provided along the outer diameter of the annular gap 14. It has the characteristics. That is, by setting the diameter of the step inner peripheral surface 8f appropriately and loading the interior O-ring 3 in contact with the step inner peripheral surface 8f, the maximum diameter X of the hydraulic cylinder C having the gap portion 14 as the cylinder chamber is set. The effective seal diameter of the interior O-ring 3 can be set.

  Then, the diameter of the inner circumferential surface 8f of the step is appropriately set so that the maximum diameter X of the hydraulic cylinder C (= the effective diameter of the interior O-ring 3) is larger than the effective diameter F of the bellows 6 as shown in FIG. Since the sealing liquid e higher in pressure than the process liquid t is supplied, the pressing force by the hydraulic cylinder C becomes weaker than the pressing force by the effective diameter F of the bellows 6. Accordingly, the pressing force due to the seal liquid e acting on the area between the diameter F and the diameter X is the pressing force due to the process liquid t acting on the area between the diameter G and the diameter F, and the bellows 6. Therefore, the retainer 8 and the first stationary seal ring 7 are pressed against each other by adding to the resultant force of the pressing force, and the first stationary seal ring 7 is not pulled out from the retainer 8.

  By the way, as shown in FIG. 3, the gap portion 14 equipped with the interior O-ring 3 has an annular shape surrounded by the three parts of the step inner peripheral surface 8 f, the atmosphere side end peripheral surface 7 c, and the interior O-ring 3. A sealed portion 19 is formed. And by the temperature rise of the apparatus accompanying the driving | operation of the double mechanical seal A, the air which exists in the sealing part 19 volume-expands, As a result, there exists a possibility that the interior O-ring 3 may dig out to a diameter inner side. Therefore, by arranging the snap ring 9 on the inner side of the inner O-ring 3 in the gap portion 14, protrusion of the inner O-ring 3 to the inner side of the inner diameter is prevented, and a good contact pressure of the first seal portion S <b> 1 is obtained. Can be maintained. Moreover, although illustration is abbreviate | omitted, it becomes a structure where the attachment position is hold | maintained by shortening the separation length of the snap ring 9 in the circumferential direction.

  As shown in FIG. 1, the second mechanical seal M2 positioned on the atmosphere side includes a second elastic mechanism 18 including a spring retainer 15, a plurality of coil springs 20, a second retainer 21, a drive pin 22, and the like, A second rotating seal ring 23 fitted into the retainer 21 and pressed and urged in the direction of the axis P by the second elastic mechanism 18 and a second stationary seal ring 24 fitted into the cover case portion 2B are provided. Configured. The second rotary seal ring 23 is externally fitted to the rotary shaft 1 so as to be movable in the direction of the axis P, and the seal surface 23a and the seal surface 24a of the second stationary seal ring 24 come into contact with each other, thereby causing the second seal portion. S2 is formed.

[Another Example]
As shown in FIG. 4, the structure in which the snap ring 9 in the first embodiment is omitted may be employed. That is, the retainer 8 is formed having an outer peripheral portion 8a into which the first stationary sealing ring 7 is tightly fitted, and a flange portion 8b extending radially inward from the outer peripheral portion 8a to receive the bellows 6. In addition, an O-ring 3 that seals the gap 14 with a diameter X that is equal to or less than the effective diameter F of the bellows 6 is provided in the gap 14 in the direction of the axis P between the first stationary seal ring 7 and the flange 8b. It is a structure. The gap 14 functions as a hydraulic cylinder C having this as a cylinder chamber.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Housing 3 O ring 5 Rotating sealing ring 6 Bellows 7 Static sealing ring 8 Retainer 8a Outer peripheral part 8b Flange part 9 Snap ring 13 Baffle cylinder 14 Crevice part 16 Seal liquid supply path 23 Rotating sealing ring 24 Static sealing ring F Bellows Effective diameter M1 first mechanical seal M2 second mechanical seal P shaft center S1 seal part S2 seal part X diameter less than the effective diameter of bellows e seal liquid t process liquid

Claims (4)

A double mechanical seal having a process-side first mechanical seal configured across the rotating shaft and the housing, and an atmosphere-side second mechanical seal configured across the rotating shaft and the housing;
The first mechanical seal is supported on the housing side so as to be able to move in the axial center direction of the rotary shaft, and an elastic material centered on the shaft center, the rotary seal ring rotating integrally with the rotary shaft A stationary seal ring fitted to an annular retainer that is pressed and urged against the rotary seal ring in the axial direction by a bellows made by the bellows, and a seal liquid having a pressure higher than the process liquid on the process side passes through the inside of the bellows A seal liquid supply path formed in the housing to supply a seal portion in contact with the seal ring and the stationary seal ring; and
The retainer is formed having an outer peripheral portion in which the stationary sealing ring is tightly fitted, and a flange portion extending radially inward from the outer peripheral portion to receive the bellows, and the stationary sealing A double mechanical seal equipped with an O-ring that seals the gap in the axial direction between the ring and the flange with a diameter less than or equal to the effective diameter of the bellows.   The double mechanical seal according to claim 1, wherein a snap ring is attached to an inner diameter side of the O-ring in the gap portion.   A baffle cylinder integrated with the housing in a state of being loosely fitted to the rotary shaft inside the bellows is equipped, and the seal liquid supplied from the seal liquid supply path is a diameter of the baffle cylinder. The double mechanical seal according to claim 1, wherein the double mechanical seal is configured to be guided to the seal portion through an outside.   The sealing liquid guided to the seal portion passes between the baffle cylinder and the rotary shaft so as to be supplied to the seal portion where the rotary seal ring and the stationary seal ring in the second mechanical seal are in contact with each other. The double mechanical seal according to claim 3, wherein the housing and the baffle cylinder are shaped.

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