JPS6353416B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a seal structure including a high-pressure airtight seal ring interposed between the sealing surface of an airtight container body and a lid plate fastened to the airtight container body, and in particular, the present invention relates to a seal structure including a high-pressure airtight seal ring interposed between a sealing surface of an airtight container body and a lid plate fastened to the airtight container body, and in particular, the present invention relates to a seal structure equipped with a high-pressure airtight seal ring interposed between a sealing surface of an airtight container body and a lid plate fastened to the airtight container body, and in particular, between an optical submarine cable and an optical submarine repeater. It is suitable for being incorporated into a connecting part. In recent years, the practical application of optical transmission systems that use optical fiber as a transmission medium has been progressing, but the optical submarine transmission system is an application of this to submarine transmission systems, and compared to conventional submarine coaxial transmission systems, the relay area is A major feature is that it can be used over long distances. However, in order to realize a long-distance optical submarine transmission system such as across oceans, tens to hundreds of optical submarine repeaters must be installed in each cable section. Therefore, it becomes essential to connect the optical submarine cable and the optical submarine repeater on board the cable-laying ship. On the other hand, optical fibers are mechanically brittle because their main component is quartz (silicon dioxide), and their mechanical strength deteriorates in environments with a large amount of moisture. Therefore, when converting optical fiber into a submarine cable, it is necessary to protect the optical cable from water pressure and prevent moisture from entering, and this also applies to optical submarine repeaters and their connecting parts. From this point of view, a connecting device for optical submarine cables as shown in FIG. 13 via a protective sleeve 14, and the optical fiber 15 from the optical repeater and the optical fiber 16 of the optical cable 12 are connected within a joint chamber 18 attached to the end plate 17 of the repeater housing 11. This is how it was done. Therefore, the optical fibers 15, 16
is exposed inside the joint chamber 18 formed by the chamber body 19 and the chamber cover 20, so in order to ensure the reliability of this optical fiber connection, the inside of the joint chamber 18 must be kept in a dry state. Must be kept airtight. Also, considering that the work will be carried out on a ship, it is desirable to simplify these structures as much as possible. By the way, in order to achieve an airtight structure for the joint chamber 18, it is possible to weld the chamber body 19, end plate 17, and chamber cover 20, or to interpose a metal seal ring between them. However, welding cannot be used because it is difficult to work on a ship, so a seal ring is used to maintain airtightness and the chamber body
9, the end plate 17, and the chamber cover 20 must be integrally fastened with bolts or the like. When a metal gasket is used, it is necessary to tighten bolts, etc. until the metal gasket is completely plastically deformed, which necessitates the use of fairly large fastening fittings, which reduces the volume inside the joint chamber 18. This deteriorates the workability of storing the connecting portions of the optical fibers 15 and 16, and also reduces the radius of curvature of the bent portions of the optical fibers 15 and 16, resulting in a decrease in reliability.
Also, when using a metal O-ring, the tightening force as much as a metal gasket is not required, but in order to obtain airtightness that corresponds to the pressure resistance of approximately 800 atmospheres required for the joint chamber 18, at least the ring A tightening force of approximately 300 kilograms per centimeter of outer circumference is required. For example, in the case of a joint chamber 18 with a diameter of about 160 mm, 9 to 12 M6 bolts are required, resulting in extremely poor assembly workability. Generally, when connecting optical submarine cables, it is necessary for a cable-laying ship to remain at a fixed location at sea for a long time, but if weather and ocean conditions are taken into consideration, the time required for onboard work must be shortened as much as possible. From this point of view, it is an object of the present invention to provide a sealing structure that can quickly and easily airtightly seal an airtight container such as the above-mentioned joint chamber. The structure of the seal structure of the present invention that achieves this object is such that an annular groove is formed in at least one of the sealing surfaces of a cylindrical airtight container body and a lid plate fastened to this airtight container body. It has a seal structure in which a metal annular airtight seal ring is installed inside, and the airtight seal ring has a semicircular cross-sectional shape and a concave side is located inside the airtight container body or on the outside high pressure side. The bent portion is pressed against the circumferential wall of the groove and pressed against the bottom surface of the groove and the sealing surface opposite thereto, so that the height h of the groove relative to the height H of the airtight seal ring is
The ratio h/H is set to 0.06 or more and less than 1, and the ratio D-d/2d between the inner diameter D of the airtight seal ring and the inner diameter d of the groove to the inner diameter d of the groove is set to 0.0055 or less. Accordingly, the airtight seal ring is elastically deformed and a portion thereof is plastically deformed. That is, as shown in FIG. 2 showing the cross-sectional structure of the high-pressure airtight seal ring incorporated in the seal structure of the present invention and FIG. 3 showing the state in which it is attached to an airtight container, the airtight seal ring 1 has a It has a metal annular shape curved in a semicircular arc shape, and is installed in an annular groove 5 formed in the sealing surface 4 of the lid plate 3 that is fastened to the airtight container body 2, with the recessed side 1a being the same as the airtight container body. It is designed to face the outside where the pressure is higher than the inside of 2. When the airtight container main body 2 and the lid plate 3 are fastened together, the airtight seal ring 1 is elastically deformed, and a part of it is also plastically deformed and pressed tightly against the sealing surface 6 of the airtight container main body 2 and the bottom surface of the groove 5. The seal surfaces 4 and 6 are hermetically sealed. In the illustrated example, the pressure outside the airtight container body 2 is higher than the inside, but if the pressure inside the airtight container body 2 is higher, the recessed side 1a of the airtight seal ring 1 It is necessary to use an airtight seal ring that is not on the outer circumferential side as shown in FIG. 2, but on the inner circumferential side. Further, the groove 5 can be provided on the sealing surface 6 of the airtight container body 2 or on both the sealing surfaces 4 and 6. Furthermore, the airtight seal ring 1 does not need to have a uniform wall thickness as shown in FIG. 2, and in the state shown in FIG. The adhesiveness with the bottom surface of 5 may be improved. When setting the height h and inner diameter (outer diameter when the direction of the recessed side 1a is reversed) d of the groove 5, the height H and inner diameter (when the direction of the recessed side 1a is reversed) of the airtight seal ring 1 is set. (outer diameter) D, but the important point is that the lid plate 3 is fastened to the airtight container body 2 to elastically deform the airtight seal ring 1 and to plastically deform a part of it. In this case, the inner diameter d of the groove 5 is set so that the bent portion 1b of the airtight seal ring 1 presses against the inner circumferential wall of the groove 5 through elastic deformation accompanied by some plastic deformation. In other words, by doing this, the bent portion 1b is pushed and expanded by the reaction force from the inner circumferential wall of the groove 5,
This is because this reaction force presses the airtight seal ring 1 even more strongly against the bottom surface of the groove 5 and the sealing surface 6 so that the height of the airtight seal ring 1 increases, contributing to improved airtightness. Next, an example in which this seal structure is applied to a joint chamber that accommodates the connection between an optical submarine cable and an optical submarine repeater will be described in detail with reference to FIG. 4, which shows an enlarged view of the joint chamber. explain. O-rings 22 made of rubber or the like are attached to the sealing portions 21 of the chamber body 19, the end plate 17, and the chamber cover 20, which are tightly fitted to each other and integrally connected by bolts or the like (not shown). It is designed to seal out liquids such as seawater that enter from the inside. Also, O-ring 2
The airtight seal ring 1 shown in FIG. It's supposed to be sealed. Here, the airtight seal ring 1 and the groove 5 mentioned earlier are
We will explain the specific dimensional relationship between the two, based on experimental results, under the condition that there will be no leakage up to 800 atmospheres.
The attached table shows the relationship between the dimensions of the airtight seal ring 1 and the groove 5, the tightening force when fastening the airtight container body 2 and the lid plate 3, the outside air (helium) pressure, and the amount of outside air intrusion (leakage). Also, the horizontal axis represents the percentage of the gap (D-d/2) between the inner diameter D of the airtight seal ring 1 in the no-load state and the inner diameter d of the groove 5 with respect to the inner diameter d of the groove 5, and the airtight seal ring in the no-load state. The vertical axis is the ratio (h/H) of the height h of the groove 5 to the height H of the groove 1, and the data in the attached table is plotted on this in Figure 5, and the points surrounded by circles indicate leakage. show something By the way, the area where the bent portion 1b of the airtight seal ring 1 comes into contact with the inner circumferential wall of the groove 5 in the assembled state has an inner diameter D.
This is the part below the solid line in Fig. 5 for the 71.6 mm airtight seal ring 1, and the inner diameter D
is the fifth in the 86.7 mm hermetic seal ring 1.

【table】

[Table] In the figure, this is the part below the broken line, and the inner diameter D is
This is the portion of the airtight seal ring 1 of 102.1 mm below the dashed line in FIG.
Also, the height H of the airtight seal ring 1 at the plastic limit point
The ratio (h/H) of the height h of the groove 5 to the height h of the groove 5 cannot be made unnecessarily small. Although this value varies depending on the material, wall thickness, size, etc. of the airtight seal ring 1, it is generally desirable for safety to set it to 0.66 or more. In addition, since h/H is 0.06 or more, the inner diameter D of the airtight seal ring 1 with respect to the inner diameter d of the groove 5
The percentage (D-d/2d) between the inner diameter d of the groove 5 and the inner diameter d of the groove 5 is about 0.55% at maximum. Therefore, the fifth
If the height h and inner diameter d of the groove 5 are set in the area surrounded by diagonal lines in the figure, airtightness with a difference of 800 atmospheres can be ensured. As is clear from the attached table, the tightening force also changes depending on the wall thickness of the airtight seal ring 1, but the larger the inner diameter D is, the lower the rigidity is, so it can be kept small. For a joint chamber 18 with a length of about 160 mm, a tightening force of about 100 to 130 kg per centimeter of ring circumference is sufficient, and this value is about one-third that of a metal O-ring, so it is difficult to tighten bolts, etc. It is possible to downsize and reduce the number of metal fittings, and it is possible to significantly improve assembly workability. As a result, the volume within the joint chamber 18 can be increased to provide room for accommodating the optical fiber connection portion, leading to improved reliability. Further, in this embodiment, the airtight seal ring 1 is attached to the seal portion 21 between the chamber body 19, the end plate 17, and the chamber cover 20. ) and the end plate 17, and since it is made of metal, there is no problem in using it in a high temperature atmosphere. Furthermore, unlike metal gaskets, the entire gasket is not completely plastically deformed, so it can be reused, and this has already been confirmed through experiments. As described above, according to the seal structure of the present invention, the recessed side of the airtight seal ring with a semicircular arc cross section is directed toward the high pressure side, and the reaction force of the bent portion of the airtight seal ring pressing against the peripheral wall of the groove causes the groove to open. Since the airtight seal ring presses strongly against the bottom and sealing surfaces, it is possible to ensure airtightness with a pressure difference of about 800 atmospheres, and the tightening force of the lid plate against the airtight container body is small. Therefore, it is possible to downsize and reduce the number of fasteners, and the assembly work can be made easier and faster.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic structure of a connection between a conventional optical submarine cable and an optical submarine repeater, FIG. 2 is a cross-sectional view showing the shape of an embodiment of a high-pressure airtight seal ring according to the present invention, and FIG. The figure is a sectional view of the sealing part of an airtight container incorporating this, FIG. The figure is a graph showing the design allowable range of groove dimensions that can withstand 800 atmospheres.The symbols in the figure are: 1 is the airtight seal ring, 1a is the recessed side, 1b
is a bent part, 2 is an airtight container body, 3 is a lid plate, 4,
6 and 21 are sealing surfaces, 5 is a groove, 17 is an end plate, 18
is the joint chamber, 19 is the chamber body, 2
0 is the chamber cover, D is the diameter of the bent portion, H is the height of the airtight seal ring, d is the diameter of the peripheral wall of the groove with which the bent portion is pressed, and h is the height of the groove.

Claims (1)

[Claims] 1. An annular groove is formed in at least one of the sealing surfaces of a cylindrical airtight container body and a lid plate fastened to the airtight container body, and a metal annular groove is formed in this groove. The seal structure is equipped with an airtight seal ring, and the airtight seal ring has a cross-sectional shape curved in a semicircular arc shape, with the concave side facing the inside of the airtight container main body or the high pressure side outside, and the bent part facing the groove. The groove is pressed against the bottom surface of the groove and the sealing surface opposite thereto, and the ratio h/H of the height h of the groove to the height H of the airtight seal ring is set to 0.06 or more and less than 1. At the same time, by setting the ratio D-d/2d between the inner diameter D of the airtight seal ring and the inner diameter d of the groove to the inner diameter d of the groove to be 0.0055 or less, the airtight seal ring is elastically deformed and A seal structure characterized in that a part of the seal is plastically deformed.