JP2010112507A - Seal unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal unit capable of effectively preventing a main seal 10 from cracking due to foaming originating from a steep deceleration from a high pressure condition and enhancing the lifetime through a reduction of the load on a subseal 20 caused by pressure accumulation to the area between the main seal 10 and the subseal 20. <P>SOLUTION: The seal unit is composed of the main seal 10 interposed between two members 110 and 120 facing each other for sealing a high pressure gas from a sealed space H and the subseal 20 positioned on the side nearer the space H than the main seal 10, interposed between the two members 110 and 120, and having a seal lip 22 facing the side opposite the space H, wherein the surface of the seal lip 22 confronting either of the two members 110 and 120 is furnished with a stepped part 221 in such an arrangement that its part nearer the seal lip 22 forefront has a smaller wall thickness, and the stepped part 221 and the forefront having smaller wall thickness can abut to the one of the two members 110, and the thicker side of the stepped part 221 is continued to the circumferential direction through a plurality of grooves. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a sealing device interposed between two members, and is used particularly in an environment where a highly permeable gas such as helium, nitrogen, carbon dioxide, hydrogen or the like is sealed and has a high pressure and a large pressure fluctuation. About things.

  Conventionally, as a sealing device for sealing a high-pressure gas with small pressure fluctuation, a packing such as an O-ring made of rubber or rubber-like synthetic resin (hereinafter referred to as rubber-like elastic material) has been used. However, if the object to be sealed is a gas such as helium, nitrogen, hydrogen or the like that has high permeability to the rubber-like elastic material and is used under conditions where pressure fluctuations such as sudden pressure reduction from a high pressure state are significant, the rubber There is a possibility that foaming cracks (blisters) may occur in the packing made of the elastic material and the sealing function may be impaired.

  That is, such a foam crack is caused when a gas made of a rubber-like elastic material is held in a high pressure state (compressed state) with a highly permeable gas to be sealed at a high pressure, and then suddenly decompressed. In addition, the high-pressure gas held inside the packing expands rapidly, and the packing is cracked by foaming.

  In order to prevent foam cracking as described above from occurring in the packing made of rubber-like elastic material, for example, the packing can be changed to a material having extremely good gas permeability, and the gas that has permeated at high pressure can be released rapidly at reduced pressure. It is effective to do. However, a material having good gas permeability tends to cause permeation leakage, and there is a problem that a sufficient sealing function cannot be obtained.

Therefore, Patent Document 1 discloses a technique for preventing a sudden pressure fluctuation of a gas to be sealed from acting on a main seal made of a rubber-like elastic material. FIG. 8 is a cross-sectional view of the conventional sealing device disclosed in Patent Document 1 in a mounted state.
JP 2004-278576 A

  In FIG. 8, reference numeral 110 is a first member, reference numeral 120 is a second member, and the cylindrical gap between the two members 110, 120 arranged concentrically is a high pressure on the right side in the figure. It communicates with the sealed space H, and the left side in the figure communicates with the atmosphere side space L. The second member 120 has annular mounting grooves 121 and 122 formed on the peripheral surface facing the first member 110, and the sealing device for sealing the gap is made of a rubber-like elastic material and has a mounting groove 121. An O-ring 101 as a main seal attached to the inner side, and a sub-seal 102 made of synthetic resin attached to the attachment groove 122 on the higher pressure side (sealed space H side) than that. The sub-seal 102 has seal lips 102a and 102b facing the atmosphere side space L, and the seal lip 102a is in close contact with the first member 110, and the seal lip 102b is in close contact with the groove bottom 122a of the mounting groove 122. The

  That is, in this sealing device, when a high gas pressure (for example, 50 MPa or more) acts from the sealed space H, the seal lips 102a and 102b of the sub seal 102 are pushed open by this pressure, and from the first member 110 and the groove bottom 122a for a moment. The gas pressure is introduced into the space C between the sub-seal 102 and the O-ring 101 because of the separation. The O-ring 101 is pressed against the inner surfaces of the first member 110 and the mounting groove 121 by the gas pressure in the space C to seal the high-pressure gas.

  When the gas pressure in the sealed space H is rapidly reduced from this high pressure state, the space C between the sub seal 102 and the O-ring 101 becomes a relatively higher pressure than the sealed space H, so that the seal lip of the sub seal 102 102a and 102b are kept in close contact with the first member 110 and the groove bottom 122a, so that the gas that has permeated and retained in the O-ring 101 at the time of high pressure suddenly drops from the O-ring 101 due to the sudden pressure reduction in the sealed space H. Therefore, foaming cracks (blisters) of the O-ring 101 can be effectively prevented.

  However, in this sealing device, the seal lips 102a and 102b of the sub seal 102 are pressed against the first member 110 and the groove bottom 122a by the pressure difference between the space C and the sealed space H when the gas pressure in the sealed space H is suddenly reduced. Therefore, when the pressure difference is large, the contact surface pressure and the contact width of the seal lips 102a and 102b with respect to the first member 110 and the groove bottom 122a also increase. Therefore, when the first member 110 and the second member 120 are relatively rotated or reciprocally moved in the axial direction, the sliding load of the seal lip 102a with respect to the first member 110 becomes remarkably large, and the sub seal 102 may be damaged.

  When the gas pressure in the sealed space H is suddenly reduced as described above, the seal lips 102a and 102b of the sub seal 102 are pressed against the first member 110 and the groove bottom 122a, and the space C is almost completely sealed. Therefore, the permeable gas confined in the space C continuously permeates the O-ring 101 while the sealed space H is depressurized, and the gas permeates and leaks into the atmosphere-side space L. There is also a risk of increasing the amount.

  The present invention has been made in view of the above points, and its technical problem is to effectively prevent foam cracking of the main seal due to sudden pressure reduction from a high pressure, and to connect between the main seal and the sub seal. The purpose is to improve the service life by reducing the load on the sub seal due to pressure accumulation.

  As a means for effectively solving the technical problem described above, a sealing device according to the invention of claim 1 includes a main seal that is interposed between two members facing each other and seals high-pressure gas from a sealed space; A sealing device comprising a sub-seal having a seal lip located between the two members and facing the opposite side of the sealed space, located on the sealed space side of the main seal, of the two members in the seal lip A stepped portion is formed on the surface facing the one or other member so that the tip end side of the seal lip is thin, and the stepped portion and the tip portion on the thinner side can contact the one or other member. Yes, the thick side of the stepped portion is intermittent in the circumferential direction by a plurality of grooves.

  According to the above configuration, the high-pressure gas in the sealed space is introduced into the space between the sub-seal and the main seal by pushing the seal lip of the sub-seal open, but the sub-seal and the main seal are rapidly depressurized. Even if the space between the two is relatively high in pressure, the seal lip has only a step portion and a tip portion on the thinner side with respect to one member or the other member of the two members facing each other. Since the contact surface pressure of the tip portion is suppressed by the lever action with the stepped portion as a fulcrum, the contact state is incomplete, and the contact state is intermittent in the circumferential direction by a plurality of grooves. Since the thick wall side of the stepped portion does not have a sealing function, the space between the main seal and the sub seal is gradually depressurized by releasing gas into the sealed space having a relatively low pressure. Therefore, even if gas permeates into the main seal at high pressure, the permeated gas does not rapidly expand / release due to decompression, which effectively prevents the occurrence of foam cracks in the main seal, and the main seal and sub seal. An increase in the load on the sub-seal due to pressure accumulation in the space is also prevented.

  According to a second aspect of the present invention, there is provided a sealing device interposed between two opposing members, a main seal for sealing high-pressure gas from the sealed space, and the second seal located on the sealed space side from the main seal. A sealing device comprising a sub-seal having a seal lip interposed between members and facing away from the sealed space, wherein at least the surface of the two members of the seal lip facing one or the other member A sheet of a material that is wider than the contact width with the other member and harder than the seal lip is integrally provided.

  According to the above configuration, the high-pressure gas in the sealed space is introduced into the space between the sub-seal and the main seal by pushing the seal lip of the sub-seal open, but the sub-seal and the main seal are rapidly depressurized. Even if the space between them becomes relatively high in pressure, the sealing lip is closely attached to one member or the other member of the two members facing each other by providing a harder material sheet. The state becomes incomplete, and the space between the main seal and the sub seal is gradually depressurized. Therefore, even if gas permeates into the main seal at high pressure, the permeated gas does not rapidly expand / release due to the reduced pressure, so that the occurrence of foam cracks in the main seal is effectively prevented. It is also possible to prevent an increase in the load on the sub seal due to the pressure accumulation in the space between them.

  According to a third aspect of the present invention, there is provided a sealing device interposed between two opposing members, a main seal for sealing high-pressure gas from the sealed space, and the second seal located on the sealed space side from the main seal. A sealing device comprising a sub-seal having a seal lip interposed between members and facing away from the sealed space, wherein a surface facing the one or the other of the two members in the seal lip is at least the It has a satin finish in a range wider than the contact width with the other member.

  According to the above configuration, the high-pressure gas in the sealed space is introduced into the space between the sub-seal and the main seal by pushing the seal lip of the sub-seal open, but the sub-seal and the main seal are rapidly depressurized. Even if the space between them becomes relatively high in pressure, the seal lip is incompletely in contact with one member or the other member of the two members facing each other due to the matte finish, so that the main seal And the space between the sub seals is gradually depressurized. Therefore, even if gas permeates into the main seal at high pressure, the permeated gas does not rapidly expand / release due to the reduced pressure, so that the occurrence of foam cracks in the main seal is effectively prevented. It is also possible to prevent an increase in the load on the sub seal due to the pressure accumulation in the space between them.

  According to the sealing device according to the first to third aspects of the present invention, foam cracking of the main seal due to abrupt pressure reduction from the high pressure state is effectively prevented, and the pressure accumulation in the space between the main seal and the sub seal is effectively prevented. Since an increase in the load on the sub-seal due to is prevented, the seal life and the sealing performance can be improved.

  Hereinafter, preferred embodiments of a sealing device according to the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a sectional view showing a first embodiment of a sealing device according to the present invention, FIG. 2 is a sectional view of an essential part of FIG. 1, and FIG. 3 is a sectional perspective view showing a sub seal in the first embodiment. FIG.

  In FIG. 1, reference numeral 110 is a first member, and reference numeral 120 is a second member, which are arranged concentrically with each other so that the cylindrical surfaces (circumferential surfaces 110 a and 120 a) face each other. 120, the right side in the figure communicates with the sealed space H, which is a high pressure, and the left side in the figure communicates with the atmosphere side space L. The first member 110 and the second member 120 correspond to two members described in the claims.

  The second member 120 is formed with annular mounting grooves 121 and 122 on the circumferential surface 120 a facing the first member 110, and a sealing device for sealing the gap is a main member mounted in the mounting groove 121. An O-ring 10 as a seal and a sub-seal 20 mounted on the mounting groove 122 on the higher pressure side (sealed space H side) than that.

  As is well known, the O-ring 10 has a circular cross section and is made of a rubber-like elastic material. The O-ring 10 is held in the mounting groove 121 and has a groove bottom 121a and a second member 110 in the first member 110. It is interposed between the member 120 and the opposed peripheral surface 110a in an appropriately compressed state.

  The sub seal 20 is made of a synthetic resin and is held in the mounting groove 122. As shown in FIG. 2, the base portion 21 whose end surface 21a faces the inner side surface 122b on the sealed space H side in the mounting groove 122 is shown. A first seal lip 22 extending from the base 21 toward the side opposite to the sealed space H (atmosphere side space L side) and in close contact with the peripheral surface 110a of the first member 110; and the sealed space H from the base 21 The first seal lip 22 has a second seal lip 23 facing the groove bottom 122a of the mounting groove 122 and extending substantially symmetrically with the first seal lip 22 toward the opposite side (atmosphere side space L side). Between the first seal lip 23 and the second seal lip 23, a substantially U-shaped groove 20a is formed.

  Further, on the surface of the first seal lip 22 facing the first member 110, as shown in FIG. 2 and FIG. 3, a step portion 221 is formed with the tip side of the first seal lip 22 being thin, The thin-walled front end portion 222 of the stepped portion 221 can abut the peripheral surface 110a of the first member 110 at the edge thereof, and the thick-walled side of the stepped portion 221 is circumferentially provided by a plurality of grooves 223. The protrusion 224 is intermittent.

  In the first embodiment configured as described above, when a high gas pressure (for example, 50 MPa or more) acts from the sealed space H, the first and second seal lips 22 and 23 of the sub seal 20 are pushed open by this pressure. The gas pressure is momentarily separated from the first member 110 and the groove bottom 122 a of the mounting groove 122, and the gas pressure is introduced into the space C between the O-ring 10 and the sub seal 20. The O-ring 10 is pressed in a compressed state against the peripheral surface 110a of the first member 110 and the inner surface of the mounting groove 121 by the gas pressure in the space C, thereby sealing the high-pressure gas.

  When the gas pressure in the sealed space H is suddenly reduced from this high pressure state, the space C between the O-ring 10 and the sub seal 20 becomes a relatively higher pressure than the sealed space H, so that the first of the sub seal 20 The second seal lips 22 and 23 are maintained in close contact with the peripheral surface 110a of the first member 110 and the groove bottom 122a of the mounting groove 122. Since only the thinner end portion 222 can be in contact with the peripheral surface 110a of the first member 110, and the surface pressure of the end portion 222 is suppressed by the lever action with the stepped portion 221 as a fulcrum, a minute gap Incomplete close contact with In addition, the protruding portion 224 on the thick side of the stepped portion 221 is in contact with the peripheral surface 110a of the first member 110, but since it is intermittent in the circumferential direction by the plurality of grooves 223, it has a sealing function. There is no. Therefore, the high-pressure gas in the space C passes through the contact portion between the first seal lip 22 and the peripheral surface 110a of the first member 110 and is gradually released to the sealed space H that has a relatively low pressure. Therefore, the space C is gradually decompressed without being suddenly decompressed.

  Therefore, even if the gas in the space C permeates the O-ring 10 made of a rubber-like elastic material at a high pressure, the permeated gas is not suddenly expanded / released due to the rapid decompression of the space C. Generation of foam cracks (blisters) in the ring 10 is effectively prevented.

  Further, as described above, since the high-pressure gas introduced into the space C is released to the sealed space H when the sealed space H is depressurized, the space C is not accumulated. Therefore, even when the first member 110 and the second member 120 are relatively rotated or reciprocally moved relative to each other in the axial direction, the sliding load of the first seal lip 22 with respect to the peripheral surface 110a of the first member 110. Is not significantly increased, and therefore the seal life of the sub seal 20 is also improved. In addition, gas permeation into the O-ring 10 does not occur while the sealed space H is depressurized, so that gas permeation leakage into the atmosphere-side space L is also suppressed.

  Next, FIG. 4 is a cross-sectional view of a principal part in a mounted state showing a second form of the sealing device according to the present invention, and FIG. 5 is a cross-sectional perspective view showing a sub-seal in the second form.

  In the second embodiment, the difference from the first embodiment described above is that at least the first seal lip 22 of the sub seal 20 is in contact with the first member 110 on the surface facing the first member 110. This is because a sheet 225 having a width w2 wider than the width w1 and harder than the synthetic resin forming the first seal lip 22 (sub-seal 20), such as PTFE (polytetrafluoroethylene), is integrated. Other portions are configured in the same manner as in the first embodiment.

  The sheet 225 may be attached to the first seal lip 22 or may be integrally formed with the first seal lip 22 (sub seal 20).

  In the second embodiment configured as described above, when a high gas pressure (for example, 50 MPa or more) acts from the sealed space H, the first and second seal lips 22 and 23 of the sub seal 20 are pushed open by this pressure. The gas pressure is instantaneously separated from the first member 110 and the groove bottom 122 a of the mounting groove 122, and the gas pressure is introduced into the space C between the O-ring 10 (see FIG. 1) and the sub-seal 20, and the high-pressure gas is sealed by the O-ring 10. Is done.

  When the gas pressure in the sealed space H is suddenly reduced from this high pressure state, the space C becomes relatively higher in pressure than the sealed space H, so that the first and second seal lips 22 and 23 of the sub seal 20 The first seal lip 22 is kept in close contact with the peripheral surface 110a of the first member 110 and the groove bottom 122a of the mounting groove 122, but the first seal lip 22 is in contact with the first member 110. Since the sheet 225 is made of a material harder than the synthetic resin forming the first member 110, the sheet 225 is not familiar with the peripheral surface 110a of the first member 110, and is in an incompletely close state having a minute gap. For this reason, the high-pressure gas in the space C between the O-ring 10 and the sub seal 20 passes between the contact surfaces of the first seal lip 22 and the peripheral surface 110a of the first member 110, and becomes a relatively low pressure. The space C is gradually discharged without being suddenly depressurized.

  Therefore, the second embodiment basically achieves the same effect as the first embodiment.

  Next, FIG. 6 is a cross-sectional view of a principal part in a mounted state showing a third form of the sealing device according to the present invention, and FIG. 7 is a cross-sectional perspective view showing a sub-seal in the third form.

  In the third embodiment, the difference from the first or second embodiment described above is that the surface of the first seal lip 22 of the sub seal 20 facing the first member 110 is at least the first member 110. In the range in which the width w2 is wider than the contact width w1, there is a satin 226, that is, a rough surface having innumerable minute irregularities. Other parts are configured in the same manner as in the first or second embodiment.

  Note that the satin 226 may be provided over the entire surface of the first seal lip 22 facing the first member 110 for convenience of processing.

  In the third embodiment configured as described above, when a high gas pressure (for example, 50 MPa or more) acts from the sealed space H, the first and second seal lips 22 and 23 of the sub seal 20 are pushed open by this pressure. The gas pressure is instantaneously separated from the first member 110 and the groove bottom 122 a of the mounting groove 122, and the gas pressure is introduced into the space C between the O-ring 10 (see FIG. 1) and the sub-seal 20, and the high-pressure gas is sealed by the O-ring 10. Is done.

  When the gas pressure in the sealed space H is suddenly reduced from this high pressure state, the space C becomes relatively higher in pressure than the sealed space H, so that the first and second seal lips 22 and 23 of the sub seal 20 The close contact state of the peripheral surface 110a of the first member 110 and the groove bottom 122a of the mounting groove 122 is maintained, but the contact surface of the first seal lip 22 with the first member 110 forms the matte 226. It becomes an incomplete intimate state due to countless minute irregularities. For this reason, the high-pressure gas in the space C between the O-ring 10 and the sub seal 20 passes between the contact surfaces of the first seal lip 22 and the peripheral surface 110a of the first member 110, and becomes a relatively low pressure. The space C is gradually discharged without being suddenly depressurized.

  Therefore, the third embodiment basically achieves the same effect as the first or second embodiment.

  As the main seal, other packings such as a square ring having a substantially square cross section, an X ring having a substantially X-shaped cross section, and a D ring having a substantially D-shaped cross section may be used. However, the O-ring 10 is most preferable as in the above embodiment.

It is sectional drawing of the mounting state which shows the 1st form of the sealing device which concerns on this invention. It is principal part sectional drawing of FIG. It is a cross-sectional perspective view which shows the sub seal | sticker in a 1st form. It is principal part sectional drawing of the mounting state which shows the 2nd form of the sealing device which concerns on this invention. It is a cross-sectional perspective view which shows the sub seal | sticker in a 2nd form. It is principal part sectional drawing of the mounting state which shows the 3rd form of the sealing device which concerns on this invention. It is a cross-sectional perspective view which shows the sub seal | sticker in a 3rd form. It is sectional drawing of the mounting state which shows the conventional sealing device.

Explanation of symbols

10 O-ring (main seal)
20 Sub seal 22 First seal lip 221 Stepped portion 222 Tip portion 223 Groove 224 Projection (thick side)
225 sheet 226 satin 23 second seal lip 110 first member 120 second member 121, 122 mounting groove C space H sealed space

Claims (3)

  A main seal that is interposed between two members facing each other and seals high-pressure gas from the sealed space, and is located on the sealed space side of the main seal and faces the opposite side of the sealed space. A sealing device comprising a sub-seal having a sealing lip, wherein a stepped portion is formed on the surface of the sealing lip facing the one or the other of the two members so that the tip end side of the sealing lip is thin. The sealing portion is characterized in that the stepped portion and the tip portion on the thinner side can contact the one or the other member, and the thicker side of the stepped portion is intermittently connected in a circumferential direction by a plurality of grooves. apparatus.   A main seal that is interposed between two members facing each other and seals high-pressure gas from the sealed space, and is located on the sealed space side of the main seal and faces the opposite side of the sealed space. A sealing device comprising a sub-seal having a sealing lip, wherein a width of the sealing lip facing the one or the other member of the two members is wider than at least a contact width with the other member, and A sealing device characterized in that a sheet made of a material harder than the sealing lip is integrally provided.   A main seal that is interposed between two members facing each other and seals high-pressure gas from the sealed space, and is located on the sealed space side of the main seal and faces the opposite side of the sealed space. A sealing device comprising a sub-seal having a sealing lip, wherein the surface of the sealing lip facing the one or other member is wider than at least the contact width with the other member. A sealing device characterized by comprising:

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