JP6529399B2 - mechanical seal - Google Patents

Description

  The present invention relates to a mechanical seal sealed by mating rings and seal rings.

  The mechanical seal is used by being mounted between the housing of the fluid device and the rotating shaft disposed so as to penetrate the housing, and the fluid leaks from the inside to the outside or from the outside to the inside of the fluid device. To prevent

  As an example of such a mechanical seal, the mechanical seal used for the shaft seal of the fluid apparatus shown by patent document 1 is demonstrated. This mechanical seal seals different fluids on the inside and the outside of the machine by the sliding contact between the sliding surface of the seal ring and the sliding surface of the mating ring. This fluid device is usually operated by a "positive pressure" in which the inside is higher than the outside, but depending on the operating conditions, it is operated by a "back pressure" in which the inside is lower than the outside. Sometimes. When transitioning from a back pressure to a positive pressure, the O-ring, which is a secondary seal, receives the pressure of the high-pressure fluid outside the aircraft, and moves inside the aircraft. Due to the movement of the O-ring, high pressure fluid on the back side of the seal ring is supplied, and a force is applied to urge the seal ring against the mating ring to maintain the desired sliding force between the sliding surfaces. ing.

JP, 2013-57353, A (paragraph 0033, FIG. 2, FIG. 3)

  The mechanical seal disclosed in Patent Document 1 maintains the desired pressing force between the sliding surfaces in both the positive pressure and the reverse pressure by moving the O-ring by the pressure difference of the fluid. . As shown in FIG. 14, the O-ring 10 is axially movably held in the O-ring holding chamber R. In the reverse pressure state, the O-ring 10 is in a state in which the bulging crest 10T protruding in the axial direction of the side face is in contact with the end face 93B on the seal ring holding ring side. In this state, when the pressure P1 on the inside of the machine and the pressure P2 on the outside of the machine reverse and become positive pressure, the low pressure P1 acts on the entire side of the machine inside of the O ring 10 Since the bulging crest 10T contacts the end face 93B to form an annular seal, the high pressure P2 acts only on the inlet side of the O-ring holding chamber R, and the region on the back side beyond the bulging crest 10T It does not work on C1. Therefore, the O-ring 10 does not move until the pressure difference between the inboard and outboard fluid acting on the O-ring 10 is an inverse ratio of the area where the respective fluids act. That is, immediately after the reverse pressure state is changed to the positive pressure state, sufficient force from the fluid on the outside of the machine is not applied to the O-ring 10 and the initial movement of the O-ring 10 is delayed. Since the force to press the seal ring to the mating ring side due to the pressure P2 of the fluid is not sufficiently exerted, there is a possibility that leakage may occur from the sliding surface of the seal ring and the mating ring.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a mechanical seal which is less likely to cause a leak from between sliding surfaces when the pressure inside and outside the machine changes. To aim.

In order to solve the above-mentioned subject, the mechanical seal of the present invention is
In a mechanical seal for axially sealing between a first area and a second area,
A mating ring having a sliding surface,
A seal ring disposed movably in the axial direction and having a sliding surface in sliding contact with the sliding surface of the mating ring;
A guide member for guiding the seal ring in the axial direction;
An O-ring sealing between the seal ring and the guide member;
An O-ring holding chamber formed by the seal ring and the guide member and holding the O-ring movably in the axial direction, wherein at least one of the axial end faces is a bulging crest in the axial direction of the O-ring And an O-ring holding chamber provided with a groove extending in the radial direction.
According to this feature, when the pressure of the fluid in the first region and the fluid in the second region shifts from the back pressure to the positive pressure, the pressure of the fluid in the high pressure region of the fluid is O when the pressure is shifted to the positive pressure. In order to act not only on the inlet side of the ring holding chamber but also on the region on the back side of the O ring holding chamber via the radially extending groove beyond the bulging crest, the O ring can be moved quickly and reliably away from the end face It can be moved. Therefore, high pressure fluid can be quickly applied to the O-ring, and leakage due to reduction in the pressing force between the sliding surfaces can be reduced.

The O-ring holding chamber is characterized in that a plurality of the grooves are provided in the circumferential direction.
According to this feature, in a state of reverse pressure by the plurality of grooves, in the bulging crest portion of the O-ring, the portion in contact with the end face is divided in the circumferential direction, so when transitioning from reverse pressure to positive pressure In addition, the O-ring can be quickly separated from the end face.

The groove is characterized in that its cross-sectional area is smaller on the back side than on the inlet side of the O-ring holding chamber.
According to this feature, when transitioning from the back pressure to the positive pressure, the fluid flowing through the groove transiently increases the pressure, and the O-ring can be quickly separated from the end face.

An intrusion suppressing means is provided to suppress the intrusion of the O-ring into the groove.
According to this feature, when the pressure difference between the first region and the second region is large, it is possible to prevent the O ring from closing the groove even if the O ring is pressed to the end face side and deformed.

It is characterized in that the groove is formed by a shallow groove and a deep groove at least a part of which overlaps at least the shallow groove.
According to this feature, the shallow groove serves as the intrusion suppressing means, and the pressure difference between the fluid in the first region and the second region is large. Even if the O ring is pressed against the end face and deformed, the shallow groove You can absorb the deformation of the O-ring and avoid closing the deep groove.

The intrusion prevention means is an interposed member disposed between the end face and the O-ring.
According to this feature, the pressure difference between the fluid in the first region and the second region is large, and the interposition member exists in front of the groove even if the O ring is pressed and deformed by the end face. It is possible to prevent the ring from closing the groove.

FIG. 2 is a cross-sectional view showing the upper half of the tandem-type mechanical seal device of Example 1; FIG. 7 is a view showing a part of the side surface of the seal ring of Example 1; FIG. 2 is an enlarged view around a secondary seal of the mechanical seal under positive pressure in Example 1; FIG. 7 is an enlarged view around a secondary seal of the mechanical seal under counter pressure in Example 1; It is an enlarged view around the secondary seal of the mechanical seal in positive pressure of Example 1, and is a figure showing the state before moving a secondary seal. It is an enlarged view which shows the principal part of FIG. 5, (a) is sectional drawing, (b) is a right view of O-ring. It is a figure which shows the seal ring of the modification 1 of Example 1, (a) is a figure which shows a part of side, (b) is a figure which shows a part of inner side. It is a figure which shows the radial direction groove of the modification 2 of Example 1. FIG. It is a figure which shows the radial direction groove of the modification 3 of Example 1. FIG. 5 is an enlarged view around a secondary seal of the mechanical seal of Example 2. FIG. FIG. 10 is a view showing a part of the side surface of the seal ring of Example 2; FIG. 16 is an enlarged view around a secondary seal of the mechanical seal of Example 3; FIG. 16 is an enlarged view around a secondary seal of the mechanical seal of Example 4; It is an enlarged view around a secondary seal of the conventional mechanical seal.

  EMBODIMENT OF THE INVENTION The form for implementing the mechanical seal which concerns on this invention is demonstrated below based on an Example.

  An example in which the mechanical seal according to the first embodiment is used as a mechanical seal device of a tandem type will be described with reference to FIGS. 1 to 9.

  Referring mainly to FIG. 1, the mechanical seal device of the tandem type seals the rotation shaft 50 between the in-machine area B1 and the out-of-machine area B3 by means of two sets of mechanical seals 1 and 21. A barrier liquid can be made to flow into and out of the intermediate region B2 formed between the mechanical seals 1 and 21 from the outside through the communication holes 41 and 44 of the housings 40 and 43. The mechanical seal 1 on the inside of the machine is mainly composed of a mating ring 2, a seal ring 3, an O-ring 10 which is a secondary seal, springs 14, 14..., Locking pins (not shown). The mechanical seal 21 on the outboard side is mainly composed of a mating ring 22, a seal ring 23, an O-ring 30 which is a secondary seal, a spring (not shown), and locking pins 28, 28.

  The sleeve 16, the spring holders 12 and 32, and the seal rings 3 and 23 rotate with the rotating shaft 50 during operation of the fluid device incorporating the tandem mechanical seal device. The sealing action by the sliding face 4S (FIG. 3) of the seal ring 3 and the sliding face 2S (FIG. 3) of the mating ring 2 and the sealing action by the O ring 10 etc. which is a secondary seal A space between area B2 is sealed. In addition, the sealing action by the sliding face of the seal ring 23 and the sliding face of the mating ring 22 and the sealing action by the O-ring 30 or the like as the secondary seal seal between the middle area B2 and the outside area B3. Be done. Hereinafter, since the mechanical seals 1 and 21 have substantially the same configuration, the mechanical seal 1 will be mainly described.

  Referring mainly to FIGS. 2 to 5, mating ring 2 is formed of SiC (silicon carbide), is non-rotatably restricted with respect to housing 40 by dowel pin 42, and is in contact with an end face of housing 40. It is mounted immovably restricted in the direction. The seal ring 3 is made of carbon, and is restricted from rotating relative to the spring holder (guide member) 12 by a locking pin (not shown but similar to the locking pins 28, 28 · · · of the mechanical seal 21). And biased by springs 14, 14... And axially movably mounted. In addition, although SiC and carbon were demonstrated as an example as a material of the mating ring 2 and the seal ring 3, another material may be sufficient.

  The seal ring 3 has an annular sliding convex portion 4 projecting to the mating ring 2 side, an annular pressed convex portion 6 provided on the axially opposite side of the sliding convex portion 4, a pressed convex portion 6 side, Annular groove 7 opened to the inner diameter side, radial direction grooves (grooves) 8, 8... (For example, five places equally in the circumferential direction), slit 9 (FIG. 2, Slit 29 (FIG. The configuration is the same as in Fig. 1). The annular groove 7 is composed of an inner peripheral surface 7A and an end surface 7B orthogonal to the axis, and the corner portions of the planar inner peripheral surface 7A and the planar end surface 7B are connected by an annular surface having a substantially quarter-circle cross section. It is done. An annular surface having a substantially quadrant cross section is not essential, but the shape having this annular surface simplifies the manufacture of the seal ring 3.

  The end surface 7B is formed with a radial direction groove 8 (FIG. 2) having a substantially semicircular shape in a side view extending from the inner diameter side to the outer diameter side. The radial length of the radial groove 8 is approximately 80% of the radial length of the end face 7B. Here, the radial length of the radial groove 8 extends to a position where the tip on the outer diameter side of the radial groove 8 faces the region C1 in a state where the O-ring 10 is pressed against the end face 7B (FIG. 4) Is preferred. In addition, it is preferable that the shape of the radial groove 8 be a shape which does not close the radial groove 8 even if the O-ring 10 is pressed and deformed. Region C1 is a space formed by the outer peripheral surface of O ring 10 and annular groove 7. Specifically, in the state of FIG. 4, the outer diameter side portion of O ring 10 and inner peripheral surface 7A The space is bounded by the annular contact portion of the O-ring 10 and the annular contact portion of the axial bulging top of the O-ring 10 and the end face 7B. In the case of an O-ring 10 having a circular cross section before compression, the bulging crest 10T in the axial direction of the O-ring 10 is located substantially at the center in the radial thickness direction.

  The seal ring 3 is axially urged by a plurality of springs 14 arranged in the circumferential direction via the pressing plate 15. The spring holder 12 is formed with a holding portion for holding the springs 14, 14... And is integrally fixed to the sleeve 16 by a bolt (not shown). Further, the sleeve 16 is integrally fixed to the rotating shaft 50 by a bolt (not shown) and rotates together with the rotating shaft 50.

  Further, in the spring holder 12, an annular groove 13 is formed on the seal ring 3 side, and together with the annular groove 7, an annular holding space for holding the O-ring 10 is formed. The annular groove 13 is formed by an outer peripheral surface 13A and a flat end surface 13B orthogonal to the axis. The annular groove 7 and the annular groove 13 form an O-ring holding chamber R for holding the O-ring 10 in the axial direction.

  Here, the O-ring 10 is formed of a rubber material and formed in a circular cross section in its natural state, and the diameter thereof is formed longer than the distance between the inner circumferential surface 7A and the outer circumferential surface 13A. In the state where the O-ring 10 is held in the O-ring holding chamber R, that is, in the state where it is mounted between the seal ring 3 and the spring holder 12, the O-ring 10 is compressed and deformed in the radial direction to It is in annular contact with 13A to form a sealing surface. Further, the O-ring 10 is disposed in the O-ring holding chamber R with a contact pressure that is movable in the axial direction by the differential pressure PL of the in-machine pressure P1 and the barrier hydraulic pressure P2. The O-ring holding chamber R may be any as long as it forms a sealing surface for sealing the O-ring 10 radially inside and outside, and holds the O-ring 10 movably in the axial direction by the pressure difference PL. . Further, the cross-sectional shape of the O-ring 10 is not limited to a circle.

Next, the operation will be described.
In the standard mode shown in FIG. 3, the internal pressure P1 is operated at a “positive pressure” (P1 <P2) lower than the barrier fluid pressure P2, but depending on the operating conditions, the internal pressure P1 shown in FIG. May be operated by "counter pressure"(P1> P2) which is higher than the barrier fluid pressure P2. As described above, in the first embodiment, the relationship between the in-machine pressure P1 and the barrier fluid pressure P2 is called positive pressure when P1 <P2 and reverse pressure when P1> P2. Regardless of the operating conditions, it is desirable to maintain the sealing performance without separation between the sliding surfaces of the mechanical seal 1.

  When shifting from reverse pressure to positive pressure, the barrier hydraulic pressure P2 that has become high pressure acts on the area C1 (FIG. 6A) through the radial groove 8. That is, the high-pressure barrier fluid pressure P2 acts on the bulging crest 10T excluding the contact portion with the end face 7B among the side surfaces of the O-ring 10 on the mating ring 2 side (FIG. 6 (b)). Since the area on which the barrier hydraulic pressure P2 acts is narrow, the O-ring 10 quickly and reliably starts moving in the axial direction away from the end face 7B by the differential pressure PL. Thereafter, when a part of the O-ring 10 separates from the end face 7B, the area in which the barrier hydraulic pressure P2 acts on the O-ring 10 further increases, and the O-ring 10 is moved quickly, and finally the positive pressure shown in FIG. It becomes a state. Therefore, immediately after the reverse pressure is shifted to the positive pressure, that is, from the time when the differential pressure PL is small, a desired force for pressing between the sliding surfaces by the barrier hydraulic pressure P2 can be secured, so that leakage occurs between the sliding surfaces. Can be suppressed.

  On the other hand, in the case where the radial groove shown in FIG. 14 is not provided (in the case illustrated in Patent Document 1), the barrier hydraulic pressure P2 does not act on the area C1, and the area where the in-machine pressure P1 acts is a barrier. Since the area on which the hydraulic pressure P2 acts is approximately twice, the O-ring 10 does not move until the barrier hydraulic pressure P2 becomes approximately twice the internal pressure P1, and there is a risk that leakage may occur from the sliding surfaces. .

In addition to the above, the radial grooves 8 extend in the radial direction, and in the state of the reverse pressure, the radial grooves 8 are seamlessly opposed in the radial direction of the O-ring 10. Therefore, the pressure of the barrier liquid in the radial groove 8 increases (the pressure rapidly increases in a short time) when the pressure is shifted from the reverse pressure to the positive pressure, so that the O ring 10 faces the radial groove 8 In the radial direction, it is easy to separate from the end face 7B because the pressure is received without a break. Furthermore, the barrier liquid penetrates into a part of the circumferentially separated parts, and the pressure of the barrier liquid acts on a plurality of parts with the part as a base point, the O ring 10 is easily separated from the end face 7B, It can be quickly separated from the end face 7B.
Moreover, since the radial direction groove | channel 8 is provided with two or more in the circumferential direction, the location which contacts the end surface 7B among the bulged top parts 10T of O ring 10 is divided | segmented in the circumferential direction (FIG.6 (b)). Therefore, the O-ring 10 can be quickly separated from the end face 7B when transitioning from reverse pressure to positive pressure.

  In addition, since the radial groove 8 extends in the radial direction, the provision of the groove does not lengthen the seal ring 3 itself having a sliding surface or reduce the mechanical strength. Since the seal ring 3 itself forms a part of the O-ring holding chamber R, and the radial direction groove 8 is provided on the end surface 7B of this seal ring, the structure is simple and easy to process. Even in the case of the seal ring 3 formed of ceramics or the like, the provision of the groove does not greatly affect the degree of freedom in design.

<Modification 1>
As shown in FIG. 7, the radial direction groove 8 may be constituted by a shallow groove (intrusion suppressing means) 8A and a deep groove 8B. Even when the differential pressure PL is large and the O-ring 10 is pressed and deformed by the end surface 7B, even if the O-ring 10 may close the shallow groove 8A, the deep groove 8B is not closed and the region C1 is reached. It is possible to avoid blocking the flow path of the The deep groove 8B may be provided so as to overlap the shallow groove 8A in the width direction. However, when the position in the width direction is at the center, the deformed O-ring 10 is more preferable because it is more difficult to intrude.
The radial grooves 8 may omit the shallow grooves 8A and may be only the deep grooves 8B. In this case, although the shallow groove 8A does not absorb the deformation of the O-ring 10 or the barrier hydraulic pressure faces the O-ring 10 in a large area, the deformed O-ring 10 does not easily block the deep groove 8B. .

<Modification 2>
As shown in FIG. 8, as the shape of the side view (FIG. 2) of the radial direction groove 8, the substantially semicircular one as in (a) has been described, but the substantially trapezoidal shape as in (b), (c) The shape may be any rectangular shape. As in (a) and (b), the width is narrowed toward the outer diameter side (the cross-sectional area of the radial groove 8 is smaller on the back side than the inlet side of the O ring holding chamber R Preferably formed). With such a shape, immediately after switching from the back pressure to the positive pressure, the flow generated in the radial groove 8 transiently increases the pressure on the center and outer diameter side by the so-called wedge effect, and the O ring 10 is rapidly It can be separated from the end face 7B.

<Modification 3>
As shown in FIG. 9, as the shape of the cross section of the radial groove 8 (FIG. 3), the substantially rectangular shape as shown in (a) has been described, but the radial groove 8 'as in (b) has the cross section It may be a substantially right triangle. In the case of (b), the chewing effect can be produced similarly to (a) and (b) of the second modification.
The structures of Modifications 1 to 3 may be combined and adopted.

  Next, Example 2 will be described with reference to FIGS. 10 to 11. The same configuration as that of the first embodiment will not be described. The second embodiment is mainly different from the first embodiment in that a ring member (intrusion suppressing means, intervening member) 18 is added. The ring member 18 is formed of metal or resin, has a slightly shorter radial length than the radial groove 8, and is disposed between the O-ring 10 and the end face 7B. When the O-ring 10 moves to the sliding surface side as a reverse pressure, the O-ring 10 has its bulging apex 10T abutting on the ring member 18. Since the radial groove 8 is longer than the ring member 18, the tip of the radial groove 8 faces the region C1. The ring member 18 is provided in the annular groove 7 so that the inner diameter side is separated from the outer peripheral surface 13A. Further, the ring member 18 does not have to be fixed to the annular groove 7 and may be movable in the axial direction. Also, the ring member 18 may be reticulated.

With this configuration, the O-ring 10 is quickly and reliably separated from the ring member 18 even when the back pressure is changed to the positive pressure, and the barrier hydraulic pressure P2 is applied to the radial groove 8 and / or the ring member 18 By acting to secure the force to push the desired sliding surface, there is no risk of leakage between the sliding surfaces. Furthermore, since the ring member 18 is provided, the O-ring 10 does not close the radial groove 8 when a reverse pressure is applied.
The same effect can be obtained even if an intervening member whose shape is other than a ring is interposed between the O-ring 10 and the end face 7B.

  Next, Example 3 will be described with reference to FIG. The same configuration as that of the first and second embodiments will not be described. In the first and second embodiments, the radial grooves 8 are provided in the seal ring 3. However, the spring holder 12 may be provided with the radial grooves 12A extending from the end on the outer diameter side to the inner diameter side. By doing this, when the positive pressure is shifted to the reverse pressure, the O-ring 10 can be reliably and quickly moved to the sliding surface side.

  A fourth embodiment will now be described with reference to FIG. The same configuration as that of the embodiment 1-3 will not be described. In Example 1-3, although the seal ring 3 demonstrated the example rotated with the rotating shaft 50, a mating ring may rotate with a rotating shaft. Further, in the first embodiment, an example in which the O-ring 10 is in contact with a part of the seal ring 3 has been described, but the O-ring may be in contact with only other members other than the seal ring.

  The mating ring 52 is configured to be held and fixed to a holder 73 fixed to the rotating shaft 50 and to rotate with the rotating shaft 50. The seal ring 53 is biased toward the mating ring 52 from the springs 64 through the spring holder 55. An O-ring 60 is disposed in a space formed by the spring holder 55 and the housing (guide member) 70. The O-ring 60 abuts against the end face of the housing 70 when the pressure is positive due to the differential pressure PL, and abuts against the end face of the spring holder 55 when the counter pressure is against. The end face of the spring holder 55 is provided with a radial groove 58 extending inward from the radial direction.

With this configuration, the O-ring 60 is quickly and reliably separated from the end face of the spring holder 55 when the positive pressure is changed to the reverse pressure, and the barrier hydraulic pressure P2 is applied to the end face of the spring holder 55. There is no risk of leakage between the sliding surfaces by securing a desired pressing force on the sliding surfaces.
The seal ring in the present invention is disposed movably in the axial direction, has a sliding surface, is provided with an end surface and the like, and may be configured by a plurality of members. In the case of the fourth embodiment, the seal ring is constituted by the seal ring 53 and the spring holder 53.

  Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions may be made without departing from the scope of the present invention. Be

  In the above-mentioned embodiment, although the tandem type mechanical seal device has been described as an example, it may be a double type or a single type. In short, it is possible to adopt the present invention as long as the relationship between the pressure of the fluid in the area inside the machine and the area outside the machine separated by the mechanical seal generates a positive pressure and a reverse pressure.

  In addition, regarding the circumferential length (width), the width of each radial groove 8, 8 ··· was described to be sufficiently shorter than the distance between the adjacent radial grooves 8 and 8; The relationship may be reversed. The same applies to the radial grooves 10A and the projections 10B.

  In addition, although the radial direction grooves 8 have been described as being equally arranged in the circumferential direction, the radial direction grooves 8 may be arranged unevenly. In this case, the fluid pressure acts on the O-ring 10 circumferentially unevenly in a transient manner immediately after the relationship between the fluid pressure in the region inside and outside the region separated by the mechanical seal is reversed. The O-ring 10 can be more quickly isolated from the end face 7B with a part as a base point. The same applies to the radial grooves 10A and the projections 10B.

Reference Signs List 1 mechanical seal 2 mating ring 3 seal ring 7 annular groove 7A inner circumferential surface 7B end surface 8, 8 ', 12 radial groove (groove)
8A Shallow groove (Intrusion control means, groove)
8B Deep groove (groove)
10 O-ring 10A Radial Groove (Channel)
10B protrusion (flow path)
10T bulging top 12 spring holder (guide member)
13 annular groove 14 spring 18 ring member (intrusion suppressing means, intervening means)
53 seal ring 55 spring holder (seal ring)
60 O-ring 70 housing (guide member)
B1 In-machine area B2 Middle area P1 In-machine pressure P2 Barrier fluid pressure R O-ring holding chamber

Claims (5)

In a mechanical seal for axially sealing between a first area and a second area,
A mating ring having a sliding surface,
A seal ring disposed movably in the axial direction and having a sliding surface in sliding contact with the sliding surface of the mating ring;
A guide member for guiding the seal ring in the axial direction;
An O-ring sealing between the seal ring and the guide member;
An O-ring holding chamber formed by the seal ring and the guide member and holding the O-ring movably in the axial direction, wherein at least one of the axial end faces is a bulging crest in the axial direction of the O-ring And the O-ring holding chamber provided with a groove extending radially in excess of the width of the groove, and the groove is formed such that its cross-sectional area is smaller on the back side than the inlet side of the O-ring holding chamber Features mechanical seal.   The mechanical seal according to claim 1, wherein a plurality of the grooves are provided in the circumferential direction in the O-ring holding chamber. The mechanical seal according to claim 1 or 2 , further comprising an intrusion suppressing means for suppressing the intrusion of the O-ring into the groove. The mechanical seal according to claim 3 , wherein the groove is formed by a shallow groove and a deep groove at least a part of which overlaps at least the shallow groove. The mechanical seal according to claim 3 , wherein the intrusion control means is an interposed member disposed between the end face and the O-ring.

Images