JPH05209687A - Sealing device for pipe connection section - Google Patents

Abstract

PURPOSE:To provide the sealing device of a pipe connection section having favorable workability, capable of being simply manufactured, and capable of securing a high sealing property under high-temperature, large-heat load operating conditions. CONSTITUTION:A ceramic spring ring 12 and a metal thin-plate ring 13 are held at a bent section 13B to manufacture a seal ring 10. The seal ring 10 is inserted into a circular groove 6 formed on a pipe body 7. A bent section 13C is protruded from the circular groove 6 by the thickness of the thin-plate ring 13. When both pipe bodies 7, 8 are fastened, the bent sections 13B, 13C are pressed to deform the ceramic spring ring 12 into a dish shape, and the ceramic spring ring 12 generates spring force. Seal faces are invariably kept in the adhesive state by the spring force, and good sealing performance can be maintained when distortion is generated on opposite facing faces 11 by a large heat load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device for a pipe connecting portion for connecting pipes for flowing fluid such as an exhaust manifold, a turbocharger and an exhaust pipe to each other.

[0002]

2. Description of the Related Art Generally, in an engine for an automobile, exhaust gas emitted from the engine is discharged into the atmosphere through an exhaust pipe, but an exhaust manifold, an exhaust pipe, and exhaust energy are provided in the middle of an exhaust system. A turbocharger equipped with a turbine driven by, a catalytic converter for detoxifying harmful substances such as carbon monoxide and nitrogen oxides contained in exhaust gas, an afterburner for burning hydrocarbons, and exhaust gas A silencer or the like for attenuating noise is provided. A seal ring is provided at a pipe connecting portion that connects the pipes for flowing fluids such as the exhaust manifold and the exhaust pipe to each other so as to maintain airtightness in the pipe connecting portion.

Conventionally, as a seal ring applied to such a pipe connecting portion, there is one disclosed in Japanese Utility Model Publication No. 2-9374. As shown in FIG. 9, the seal ring 36 includes a hollow ring 37 formed by rolling a ring-shaped thin metal plate into an annular shape having a circular cross section, and a gasket material containing a non-heat-resistant substance filled in the hollow ring 37. And 38.

Then, as shown in FIGS. 7 and 8, the surface of the flange 34 of one pipe 32 is formed into a flat surface, and the other pipe 3 is formed.
1. An annular groove 35 is formed on the surface of the flange 33 of No. 1, and the annular groove 3
5, a part of the seal ring 36 is fitted in a state of protruding from the annular groove 35, and in this state, the flanges 33 and 34 of the two pipes 31 and 32 are aligned with each other and tightened by using a bolt and a nut. The pipes 31 and 32 are connected to each other while maintaining airtightness. At this time, the seal ring is elastically compressed between both flanges and pushed into the annular groove, and both flange surfaces are in close contact with each other. In this state, the airtightness of both flanges is determined by the annular groove formed in the flange. The spring action of the seal ring that is about to protrude causes the seal ring to be maintained by being strongly pressed against the flange surface.

However, the pipe connecting portion connecting the outlet pipe of the exhaust manifold and the inlet pipe of the turbocharger has a high temperature (for example, 750 ° C. or higher) in use, and is used for the pipe connecting portion at the high temperature portion. The seal ring will be exposed to high temperatures. Therefore, when the conventional seal ring is used, the gasket material filled in the metal seal ring is thermally decomposed by the organic component of the binder contained in the gasket material, or thermally decomposed. There is a phenomenon that the volume of the gasket material decreases with the scattering. When the seal ring filled with the gasket material as described above is sandwiched between the flange surfaces of both pipes and connected with bolts and nuts, the gasket material is subjected to heat load as described above and the volume of the gasket material decreases. As a result, the elastic compression force of the seal ring becomes small, and the sealing property of the contact surface of the pipe connecting portion deteriorates.

Further, regarding a pipe connecting portion in which a seal ring filled with a gasket material is sandwiched between flange faces of both pipes and connected by a bolt and a nut, the flange face of the pipe connecting portion is repeatedly used at high temperature and room temperature. When subjected to the heat load, the both flange surfaces are distorted, the flange surfaces are deformed, and the seal ring cannot be satisfactorily abutted, so that the sealing performance of the pipe connecting portion is further deteriorated.

Further, Japanese Patent Publication No. 62-2188 discloses that
A seal member used for joining exhaust turbocharger flanges is disclosed. The seal member includes a filler,
And a metal jacket having a hollow ring shape enclosing the filling material and having joints at both ends along the ring circumferential direction. The metal jacket is doubled or tripled, and the joints at both ends are offset from each other. By shifting the seams of the metal jackets from each other, this sealing member can considerably prevent the medium or air to be sealed from entering through the gaps between the metal jackets. This is not a perfect seal member to be used in the above, and in the end, the problem that the filler is deteriorated due to oxidation or the like and the sealing property is deteriorated is not completely solved.

[0008]

SUMMARY OF THE INVENTION As mentioned above, the above-mentioned Japanese Utility Model Publication No. 2-9374 or Japanese Patent Publication No. 62-218.
Both of the conventional seal rings disclosed in Japanese Patent Publication No. 8 have a fundamental problem in that they use a material that may be deteriorated due to high temperature and large heat load.

Therefore, it is conceivable to make a seal ring without using a gasket material which is easily affected by heat and using a material having excellent heat resistance which is not affected by heat, for example, a material such as ceramics or heat-resistant alloy. To be However, in that case, it is necessary to provide a heat-resistant material seal ring with a spring function so as to be able to cope with a heat load. Therefore, it is conceivable to process the seal ring itself into, for example, a disc spring shape in order to give the seal ring a spring function, but it is considerably difficult to accurately process the heat-resistant material into a special shape. It involves an increase in manufacturing cost. On the other hand, it is easy and cost-effective to process the seal ring into a flat plate shape, but the flat plate seal ring itself does not generate a spring action, and therefore cannot handle a heat load. Therefore, in this case, how to give the flat plate-shaped seal ring a function as a spring is a problem.

Therefore, an object of the present invention is to solve the above-mentioned problems, and a pair of pipes having opposing surfaces facing each other and tightened together, and between the facing surfaces facing each other of the tubular body. A sealing device for a pipe connection part having a arranged seal ring can be easily manufactured without requiring high processing accuracy, and can maintain high sealing performance even under high temperature and heavy heat load use conditions. It is an object of the present invention to provide a sealing device for a pipe connection part.

[0011]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a sealing device for a pipe connecting portion, which includes a pair of pipes having opposed faces facing each other and tightened together, and a seal ring arranged between the opposed faces of the pipes facing each other. Comprises a flat plate heat-resistant spring ring and a thin plate ring which is in contact with a flat surface of the heat-resistant spring ring and has a bent portion at a radial edge portion and has a step in a radial thickness. The sealing device for a pipe connecting portion is characterized in that the heat resistant spring ring is deformed into a dish shape by the step of the thin plate ring when the pair of pipe bodies are tightened.

Further, in the sealing device for the pipe connecting portion,
The heat resistant spring ring is made of ceramics.

Further, in the sealing device for the pipe connecting portion,
The opposing surface of at least one of the tubular bodies is formed into an annular groove.

Further, in the sealing device for the pipe connecting portion,
The bent portion of one radial edge of the thin plate-shaped ring holds the heat-resistant spring ring, and the bent portion of the other radial edge is opposite to the heat-resistant spring ring. It is bent.

Alternatively, in the sealing device for this pipe connection,
The thin plate-shaped ring includes a first thin plate-shaped ring having a bent portion formed by bending a radially outer edge portion and a second thin plate-shaped ring having a bent portion formed by bending a radially inner edge portion,
The heat resistant spring ring is disposed between the first thin plate ring and the second thin plate ring.

Alternatively, in the sealing device for the pipe connection,
The thin plate-shaped ring is composed of a pair of grommets that respectively hold the radial edges of the heat-resistant spring ring with a wire ring interposed therebetween, and the wire rings are opposite to the surface of the heat-resistant spring ring. It is located in.

Alternatively, in this sealing device for a pipe connecting portion, the thin plate-shaped ring has a pair of bent portions bent in an L-shaped cross section and arranged at a pair of radial edges of the heat-resistant spring ring. Each of the L-shaped rings is arranged on the opposite side to the surface of the heat-resistant spring ring.

[0018]

The sealing device for the pipe connecting portion according to the present invention is constructed as described above and operates as follows. That is, even if the heat-resistant spring ring forming the seal ring is made of a material such as ceramics or heat-resistant alloy steel having excellent heat resistance, the heat-resistant spring ring is formed into a flat flat plate shape. It can be easily manufactured without requiring high processing accuracy. Further, the thin plate-shaped ring that constitutes the seal ring can be formed by bending since it can be made of a metal material.

This flat plate-shaped heat-resistant spring ring is integrally assembled with the thin plate-shaped ring and is fitted into the annular groove formed between the facing surfaces, particularly in the facing surface, so that a part of the thin plate-shaped ring projects from the annular groove. Since the seal ring is fitted in the annular groove, when the pair of pipes are tightened, the step formed on the thin plate ring, in other words, the step portion protruding from the annular groove serves to flatten the flat plate. -Shaped heat-resistant spring ring deforms into a dish. Since the heat-resistant spring ring has a spring action in the dish-shaped state of the heat-resistant spring ring,
Even if a large heat load is applied, the sealing surface is always in close contact, and high sealing performance can be maintained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a sealing device for a pipe connecting portion according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of an exhaust manifold incorporating a sealing device for a pipe connection portion according to the present invention, and FIG. 2 is a side view as seen from the line AA side in FIG.

As shown in FIGS. 1 and 2, the exhaust manifold 1 is attached to the cylinder head of an in-line 6-cylinder engine. The exhaust manifold 1 includes mounting flange portions 2A and 2B that are mounted on the cylinder head. The exhaust manifold 1 is composed of a first exhaust manifold 1A and a second exhaust manifold 1B each having three mounting flange portions 2A and 2B corresponding to three cylinders. First exhaust manifold 1A and second exhaust manifold 1B
Are connected by a flexible joint 4 made of a bellows. Further, the first exhaust manifold 1A and the second exhaust manifold 1B
Respectively have outlet pipes 3A and 3B which are collecting pipes. These outlet pipes 3A and 3B are connected to inlets 5A and 5B of a turbocharger provided downstream of the engine by tightening bolts and nuts. In such a configuration, the exhaust gas discharged from the engine passes through the exhaust ports of the cylinders and the mounting flange portions 2
It is collected in outlet pipes 3A and 3B through respective branch passages formed in the central portions of A and 2B, and then fed into the turbocharger through inlets 5A and 5B of the turbocharger.

The pipe connecting portion sealing device according to the present invention comprises a collecting pipe of the exhaust manifold 1, ie, a pipe body 7 of the outlet pipes 3A and 3B.
And is incorporated in the tubular body 8 of the inlet pipes 5A, 5B of the turbocharger. Opposing faces 9 are formed at the ends of the outlet pipes 3A, 3B of the exhaust manifold 1, and facing faces 11 are formed at the ends of the inlet pipes 5A, 5B of the turbocharger. The facing surface 9 formed at the end of the pipe body 7 of the outlet pipes 3A and 3B of the exhaust manifold 1 faces the facing surface 11 of the pipe body 8 of the inlet pipes 5A and 5B of the turbocharger, and the annular groove 6 is formed.
Are formed respectively. A seal ring 10 is incorporated in these annular grooves 6.

FIG. 3 is a sectional view showing an embodiment of a sealing device for a pipe connecting portion according to the present invention. The seal ring 10 in this sealing device has a ceramic spring ring 12 as a heat resistant spring ring and a thin plate ring having a function of deforming the ceramic spring ring 12 into a dish shape when the pair of pipes 7 and 8 are tightened. 13 and 13. The ceramic spring ring 12 is made of ceramics having excellent heat resistance and has flat or flat flat surfaces 12A and 12B in a normal state where no load is applied. 12A and 12B act as springs by deforming into a dish shape forming a tapered surface. The plate thickness of the ceramic spring ring 12 is, for example, 0.1 to 1.
It is 0 mm. In this embodiment, three ceramic spring rings 12 are used in a stacked manner, but a plurality of such spring rings 12 can be used in a stacked manner in order to increase the force required as a spring. The thin plate-shaped ring 13 is manufactured by bending using a metal material that has good workability and is inexpensive. For example, the material of the thin plate ring 13 is preferably aluminum, SUS material, or ordinary steel.

The thin plate-shaped ring 13 is arranged so as to be in full contact with one flat surface 12B of the ceramic spring ring 12. The thin plate-shaped ring 13 includes a flat plate portion 13A, a bent portion 13B that holds a heat resistant spring ring formed on the inner diameter side of the radial edge portion, and a bent portion 1 formed on the outer diameter side of the radial edge portion.
Have 3C. The holding portion 13B holds the inner diameter portion of the ceramic spring ring 12. The bent portion 13C is bent on the side opposite to the side of the ceramic spring ring 12 and is in contact with the flat end surface of the tube body 8, that is, the facing surface 11.

The seal ring 10 is a thin plate ring 1.
The three bent portions 13B are held and held by the ceramic spring ring 12 to be integrally assembled. The assembled seal ring 10 is attached to the annular groove 6 of the pipe body 7.
Then, the pipe body 7 and the pipe body 8 are fastened with a fixing means such as bolts and nuts to be assembled to the pipe connecting portion. In the state before tightening the two pipes 7 and 8, the seal ring 10 fitted in the annular groove 6 is the thin plate ring 1
A bent portion 13C corresponding to the plate thickness of 3 projects from the annular groove 6 to form a step with respect to the facing surface 11 of the tubular body 8. Therefore, when the two pipes 7 and 8 are tightened, the ceramic spring ring 12 has the bent portion 13B and the bent portion 13 of the thin plate ring 13.
It is pressed by C and deformed into a dish shape, and a spring force is generated. Due to this spring force, the bent portion 13B of the thin plate-shaped ring 13 is pressed against the bottom surface of the annular groove 6, and the bent portion 13C is pressed against the facing surface 11 of the tubular body 8 to be in close contact with each other. Facing surface 1 facing due to
Even if 1 is distorted, the generated spring force can maintain good sealing performance.

FIG. 4 is a sectional view showing another embodiment of the sealing device for a pipe connecting portion according to the present invention. The thin plate ring is composed of a pair of thin plate rings 14 and 15 made of a metal material. The thin plate ring 14 has a flat plate portion 14A.
And the outer diameter side of the radial edge part are made of ceramic spring ring 12
The bent portion 14B is formed by bending it to the side. The thin plate ring 15 is composed of a flat plate portion 15A and a bent portion 15B formed by bending the inner diameter side of the radial edge portion toward the ceramic spring ring 12 side. Ceramic spring ring 12
Has flat flat surfaces 12A and 12B, and has a bent portion 14B of the thin plate ring 14 and a bent portion 1 of the thin plate ring 15.
It is arranged between 5B and 5B. The seal ring 10 composed of the ceramic spring ring 12 and the thin plate-shaped rings 14 and 15 is fitted into the annular groove 6 formed in the tube body 7.

In this embodiment, the ceramic spring ring 12 is formed by bending the thin plate-shaped rings 14 and 15 into bent portions 14B and 15B.
The pipe body 7 and the pipe body 8 are fitted in the annular groove 6 and are tightened by fixing means such as bolts and nuts, so that the pipe body 7 and the pipe body 8 are assembled to the pipe connecting portion. In a state before tightening the two pipe bodies 7 and 8, the seal ring 10 fitted in the annular groove 6 is provided.
Is protruded from the annular groove 6 by the thickness of the thin plate ring 15 to form a step with respect to the facing surface 11 of the tubular body 8. Therefore, when the two pipes 7 and 8 are tightened, the ceramic spring ring 12 is pressed by the two bent portions 14B and 15B of the thin plate-shaped rings 14 and 15 to be deformed into a dish shape, and a spring force is generated. Due to this spring force, the bent portion 14B of the thin plate ring 14 is pressed against the bottom surface of the annular groove 6 and the bent portion 15B is pressed against the facing surface 11 of the tubular body 8 to be in close contact with each other, and face each other due to a large heat load. Even if the opposing surface 11 is distorted, good sealing performance can be maintained by the generated spring force.

FIG. 5 is a sectional view showing still another embodiment of the sealing device for a pipe connecting portion according to the present invention. In this embodiment, the seal ring 10 is a ceramic spring ring 1.
2. A grommet 16 arranged on the outer diameter side of the radial edge of the ceramic spring ring 12 and a grommet 17 arranged on the inner diameter side of the radial edge of the ceramic spring ring 12. There is. The thin plate ring is composed of a pair of grommets 16 and 17, and the grommets 16 and 17 hold the radial edges of the heat resistant spring ring 12 with the wire rings 18 and 19 interposed therebetween. The wire rings 18 and 19 are arranged on the opposite sides of the surfaces 12A and 12B of the heat resistant spring ring 12, respectively. Grommets 16 and 17 are
The cross-section is formed into a U shape by bending.
The grommet 16 sandwiches the outer diameter side of the ceramic spring ring 12 and the wire ring 18, and the grommet 17 holds the inner diameter side of the ceramic spring ring 12 and the wire ring 19.
Is sandwiched between. The wire ring 18 is arranged on the upper flat surface 12A of the ceramic spring ring 12, and the wire ring 19 is arranged on the lower flat surface 12B of the ceramic spring ring 12.

The seal ring 10 is provided with the wire ring 1 on the outer diameter side of the radial edge of the ceramic spring ring 12.
8 are stacked and sandwiched by grommet 16 for crimping, and wire ring 19 is stacked on the inner diameter side of the radial edge of ceramic spring ring 12 and sandwiched by grommet 17 for crimping to assemble. To be The assembled seal ring 10 is fitted into the annular groove 6 and is tightly attached to the pipe bodies 7 and 8 by fixing means such as bolts and nuts, so that the seal ring 10 is attached to the pipe connecting portion. In the state before tightening the two pipes 7 and 8, the seal ring 10 fitted in the annular groove 6 projects from the annular groove 6 by the thickness of the wire ring 19 and forms a step with respect to the facing surface 11 of the tubular body 8. You can Therefore, when the two pipes 7 and 8 are tightened, the ceramic spring ring 12 is pressed by the step difference between the grommets 16 and 17 and becomes a tapered surface in the radial direction to be deformed into a dish shape, and a spring force is generated. Due to this spring force, the grommet 16 is on the bottom surface of the annular groove 6, and the grommet 17 is on the facing surface 1.
Even if they are pressed against each other 1 and come into close contact with each other, and even if the opposing facing surfaces 11 are distorted, good sealing performance can be maintained by the generated spring force.

FIG. 6 is a sectional view showing another embodiment of the sealing device for a pipe connecting portion according to the present invention. The thin plate ring is composed of a pair of L-shaped rings 20 and 21 made of a metal material, and is formed into an L-shaped cross section by bending. The heat-resistant spring ring is made of a ceramic spring ring 12 and has flat surfaces 12A and 12B on both sides. The L-shaped ring 20 is arranged on the outer diameter side of the radial edge of the ceramic spring ring 12, and the L-shaped ring 21 is arranged on the inner diameter side of the radial edge of the ceramic spring ring 12. As shown in FIG. 6, the L-shaped rings 20 and 21 are arranged on the flat surfaces 12A and 12B on the opposite sides of the ceramic spring ring 12, respectively.

In this embodiment, the seal ring 10 is L
It is composed of mold rings 20 and 21 and a ceramic spring ring 12. The seal ring 10 is fitted into the annular groove 6 formed in the pipe body 7, and the pipe body 7 and the pipe body 8 are bolted together.
It is assembled to the pipe connecting portion by tightening with a fixing means such as a nut. In the state before tightening the two pipes 7 and 8, only the plate thickness of the L-shaped ring 21 projects from the annular groove 6 to form a step with respect to the facing surface 11 of the pipe 8. For this reason, when the two pipes 7 and 8 are tightened, the ceramic spring ring 12 is pressed by the L-shaped ring 20 and the L-shaped ring 21 and deformed into a dish shape having a tapered surface inclined in the radial direction, and the spring force is increased. Occur. Due to this spring force, the L-shaped ring 20 is pressed against the bottom surface of the annular groove 6 and the L-shaped ring 21 is pressed against the facing surface 11 of the tubular body 8 to be in close contact with each other, and even if the facing facing surface 11 is distorted. Good sealing performance can be maintained by the spring force generated.

In the above embodiment, the material of the heat resistant spring ring is ceramics, but in addition, heat resistant alloy steel, tool steel (SKD, SKH), stainless steel (SUS630),
A heat-resistant metal material such as Inconel (trade name), high nickel steel, titanium, and Herons alloy (HA214, trade name) may be used.

[0033]

The sealing device for the pipe connecting portion according to the present invention comprises:
Since it is comprised as mentioned above, the following effects are produced. That is, although heat-resistant materials such as ceramics and heat-resistant alloy materials have poor workability, they are easy to process because they are only processed into heat-resistant spring rings in the sealing device for this pipe connection part, flat plate-shaped rings. It can be processed with high precision. On the other hand, the thin plate ring for deforming the heat resistant spring ring into a dish shape can be made of a metal material, and a low cost material excellent in workability can be used, so that it can be easily processed into a special shape. Therefore, the sealing device for the pipe connecting portion can be easily processed at low cost.

When the flat plate-shaped heat-resistant spring ring is fitted into the annular groove formed in the pipe body to tighten the pair of pipe bodies, the flat plate-shaped heat-resistant spring ring is acted upon by the action of the thin plate-shaped ring. Transforms into a shape. In this dish-shaped state, the heat-resistant spring ring causes a spring action, so that even if the opposing end faces are distorted by a large heat load, the sealing faces can always maintain a close contact state and have a high pipe connection. The sealing property can be secured.

Further, the sealing device for the pipe connecting portion is composed only of a heat resistant spring ring and a thin plate ring,
Since no material that is easily affected by heat is used, the problem of volume reduction, deformation, alteration, cracking, etc. does not occur even if a large heat load is applied, and the sealing performance does not deteriorate. Absent.

Further, by disposing a metallic thin plate ring made of a relatively soft material on the opposing surfaces, that is, the sealing surfaces, the sealing surfaces come into direct contact with high hardness materials such as ceramics and heat-resistant alloy steel. Good sealing performance is secured as compared with the case. Further, since the heat-resistant spring ring is held by the thin plate-shaped ring, the heat-resistant spring ring is less likely to be scratched during use, and the durability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an exhaust manifold incorporating a sealing device for a pipe connection portion according to the present invention.

FIG. 2 is a side view seen from the line AA side in FIG.

FIG. 3 is an enlarged cross-sectional view of a portion of a region B of FIG. 1, which is a cross-sectional view showing an embodiment of a sealing device for a pipe connecting portion according to the present invention.

FIG. 4 is an enlarged cross-sectional view of a region B of FIG. 1, showing another embodiment of the sealing device for a pipe connecting portion according to the present invention.

5 is an enlarged cross-sectional view of a region B in FIG. 1, showing another embodiment of the sealing device for a pipe connecting portion according to the present invention.

FIG. 6 is an enlarged cross-sectional view of a region B in FIG. 1, showing another embodiment of the sealing device for a pipe connecting portion according to the present invention.

FIG. 7 is a cross-sectional view showing an example of a conventional sealing device for a pipe connecting portion.

FIG. 8 is a perspective view showing an example of a flange in the sealing device for the pipe connecting portion of FIG. 7.

9 is a cross-sectional view showing an example of a seal ring in the sealing device of the pipe connecting portion of FIG.

[Explanation of symbols]

 6 Annular groove 7,8 Tube body 9,11 Opposing surface 10 Seal ring 12 Ceramic spring ring (heat resistant spring ring) 12A, 12B Flat surface 13,14,15 Thin plate ring 13C, 14B, 15B Bending part 16, 17 Grommet (thin plate ring) 18,19 Wire ring 20,21 L-shaped ring (thin plate ring)

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Yoshinori Dowita, 248 Kano, Higashi-Osaka, Osaka Prefecture, Japan Gasket Co., Ltd. (72) Inventor, Akihiro Imai, 248, Kano, Higashi-Osaka, Osaka Stocks, Japan Gasket In the company

Claims (7)

[Claims] 1. A sealing device for a pipe connecting portion, comprising a pair of pipes having opposed faces facing each other and tightened with each other, and a seal ring arranged between the opposed faces of the pipes, wherein the seal is provided. The ring is composed of a plate-shaped heat-resistant spring ring and a thin plate-shaped ring that is in contact with the flat surface of the heat-resistant spring ring and that has a bent portion at the radial edge and has a step in the radial thickness. A sealing device for a pipe connecting portion, wherein the heat-resistant spring ring is deformed into a dish shape by the step of the thin plate ring when the pair of pipe bodies are tightened. 2. The sealing device for a pipe connecting portion according to claim 1, wherein the heat-resistant spring ring is made of ceramics. 3. The sealing device for a pipe connecting portion according to claim 1, wherein the facing surface of at least one of the pipe bodies is formed as an annular groove. 4. The bent portion of one radial edge of the thin plate-shaped ring holds the heat-resistant spring ring, and
The sealing device for a pipe connecting portion according to claim 1, wherein the bent portion of the other radial edge portion is bent on the side opposite to the heat resistant spring ring. 5. The thin plate-shaped ring includes a first thin plate-shaped ring having a bent portion formed by bending a radially outer edge portion and a second thin plate-shaped ring having a bent portion formed by bending a radially inner edge portion. The sealing device for a pipe connecting portion according to claim 1, wherein the heat-resistant spring ring is arranged between the first thin plate-shaped ring and the second thin plate-shaped ring. 6. The thin plate-shaped ring is composed of a pair of grommets that respectively hold both radial edges of the heat-resistant spring ring with a wire ring interposed therebetween, and each wire ring is formed on a surface of the heat-resistant spring ring. The sealing device for a pipe connecting portion according to claim 1, wherein the sealing devices are arranged on opposite sides of each other. 7. The thin plate-shaped ring has a cross section L at the bent portion.
It is composed of a pair of L-shaped rings that are bent in a letter shape and are arranged at both radial edges of the heat-resistant spring ring, and each L-shaped ring is on the opposite side of the surface of the heat-resistant spring ring. The sealing device for a pipe connecting portion according to claim 1, wherein the sealing device is arranged respectively.