JP2000204942A - Sealing device for exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device for an exhaust pipe to reliably seal a portion, where the two cylindrical end parts of a pair of division exhaust pipes are inserted in each other for coupling, with high sealing ability. SOLUTION: The cylindrical small end part 3 of a second division exhaust pipe 2 being one of intercoupled division pipes is inserted in the cylindrical large end part 8 of a first division exhaust pipe 1 being the other of them, and a seal ring 6 having an outer peripheral edge making contact with the inner wall surface f2 of a cylindrical large end part 8 is fitted in the annular recessed groove 5 of the outer wall surface f1 of the cylindrical small end part 3. In a so formed sealing device for an exhaust pipe, a backup ring 7 serving as an axial elastic press member elastically compression-deformed in the direction of the common axis L is arranged in an annular gap having a gap width (e) between the inside surface of the annular recessed groove 5 and the seal ring 6.

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 an exhaust pipe in which a pair of split exhaust pipes to be connected to each other are inserted into and joined to each other by a seal ring, and more particularly, to a sealing device for an exhaust pipe. The present invention relates to a sealing device for an exhaust pipe suitable for improving sealing performance by a ring.

[0002]

2. Description of the Related Art An internal combustion engine discharges high-temperature and high-pressure exhaust gas into the atmosphere at low temperature and low pressure by passing it through an exhaust pipe and an exhaust gas post-treatment device. The exhaust pipe used here is formed of a metal pipe in consideration of heat resistance and pressure resistance, and when this is subject to restrictions on layout or installation workability, or when it is necessary to cope with expansion and contraction due to temperature change of the metal pipe The plurality of divided exhaust pipes need to be connected so as to be able to absorb a longitudinal displacement. When the exhaust pipe is formed of a plurality of divided exhaust pipes connected to each other as described above, the connection end portions of the respective divided exhaust pipes are inserted and connected to each other when mounted on the vehicle body side, and the airtightness of the same part is sealed by a sealing device. Will be secured.

[0003] As a sealing device used for a connecting portion of a pair of divided exhaust pipes joined together as described above, for example, a sealing device shown in Fig. 9 is known. The sealing device is provided with one of the cylindrical large end portions 13 of the pair of divided exhaust pipes 110 and 120.
A seal ring 150 seals the space between 0 and the other small cylindrical end 140 inserted therein. A single or a plurality of (one in FIG. 9) seal rings 160 are disposed in the direction of the common axis L of the cylindrical ends 130 and 140 of the respective divided exhaust pipes. The inner peripheral end of the seal ring 150 is fitted into the annular groove 160 of the small cylindrical end 140, and the outer peripheral end thereof is in contact with the inner wall surface of the large cylindrical end 130. Exhaust gas pressure leaking into the annular groove 160 from the exhaust path R is
0 is received, the one side wall surface has a common axis L of the two cylindrical ends.
, The low wall surface receives the exhaust gas pressure P2 in the radially expanding direction, whereby the other side wall surface of the seal ring 150 is pressed against the inner side surface of the annular groove 160, and the seal ring 150 has a cylindrical large end 130
To prevent the exhaust gas from leaking to the atmosphere.

However, the gas pressure of the exhaust gas leaking into the annular groove 160 is relatively low, and the pressure contact between the seal ring 150 and the inner surface of the annular groove 160 and the inner wall surface of the large cylindrical end 130 is reduced. It is not possible to secure enough pressing force to hold
There was a problem that sealing performance was low. Therefore, the elastic ring (FIG. 9) urged to expand the diameter on the low wall surface of the seal ring 150 is used.
(Indicated by a two-dot chain line in FIG. 2), and a seal ring 150 is securely pressed against the inner wall surface of the cylindrical large end portion 130 to ensure the sealing property. 6
No. 0572 discloses a conventional example.

[0005]

By the way, when the elastic ring S which can be elastically displaced in the radially expanding direction is used as described above, the sealing performance between the seal ring 150 and the inner wall surface of the large cylindrical end 130 is required. However, the sealing property between the seal ring 150 and the inner surface of the annular groove 160 cannot be ensured. Japanese Patent Publication No. 6-60572 discloses an expander ring that is elastically displaceable in the radially expanding direction, inclines a low wall surface of a seal ring with which the ring abuts, and expands the lower wall surface received from the expander ring. It has been proposed to divide the elastic force in the radial direction, that is, to generate a component force in the direction of the common axis of the two cylindrical connection ends, thereby pressing the seal ring against the side surface of the annular groove. I have.

However, the function of dividing the component force in the direction of the common axis at which the expander ring occurs is relatively low, and it is difficult to generate a component force that can sufficiently secure the sealing property between the seal ring and the side surface of the annular groove. . In particular, if the inclined low wall surface of the expander ring deteriorates with time, the portion of the inclined low wall surface with which the expander ring abuts tends to be concavely deformed with time. There is a problem that the sealing performance is further reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exhaust pipe sealing device capable of reliably sealing a portion where two cylindrical ends of a pair of split exhaust pipes are inserted and connected to each other with good sealing properties.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a cylindrical small end of one of the divided exhaust pipes is connected to a cylindrical large end of one of the divided exhaust pipes. Insert the ends and seal the seal between them,
An exhaust pipe sealing device which is fitted into an annular groove on the outer wall surface of the cylindrical small end portion and whose outer peripheral edge is in contact with the inner wall surface of the cylindrical large end portion; An axial elastic pressing member elastically deformed by compression in the direction of the common axis of the end portion is provided, and after the axial elastic pressing member is compressed and deformed, an annular gap between the inner surface of the annular groove and the seal ring is formed. It fits. Here, the seal ring abuts against the inner wall surface of the large cylindrical end, and the compressively deformed axial elastic pressing member presses the seal ring in the direction of the common axis of both cylindrical ends. Therefore, it is possible to reliably prevent the exhaust gas from leaking to the atmosphere side through the annular gap between the inner surface of the annular groove and the seal ring, thereby improving the sealing performance.

According to a second aspect of the present invention, in the exhaust pipe sealing device according to the first aspect, the seal ring is partially cut in a circumferential direction and formed so as to be elastically displaceable in a radially increasing direction. I do. In this case, the seal ring enhances the sealing property between the inner wall surface of the cylindrical large end and the outer peripheral edge of the seal ring, and the axial elastic pressing member increases the sealing property between the inner surface of the annular groove and the seal ring. Is strengthened, so that the overall sealing performance can be sufficiently improved.

According to a third aspect of the present invention, in the exhaust pipe sealing device according to the first aspect, the axial elastic pressing member is formed so as to be elastically deformable in diameter, and has a concave shape that reduces the cross-sectional rigidity in the radial cross section. A notch is formed, and the diameter is reduced and deformed, and a radial cross section is inclined in the common axis direction to be fitted into the annular gap. In this case, the axial elastic pressing member forms a concave cut in the radial cross section to give a deviation in the left and right cross-sectional rigidity in the common axial direction of the radial cross section, and when the diameter is reduced, the left and right cross-sectional rigidity is reduced. The radial cross section is inclined in the direction of the common axis in accordance with the deviation of the radial direction to increase the width in the same direction, and is fitted in the annular gap of the annular groove in that state. For this reason, the axial elastic pressing member can elastically press the seal ring in the common axial direction, and can reliably prevent exhaust gas from leaking to the atmosphere side through the annular gap between the inner surface of the annular groove and the seal ring. Performance can be improved.

According to a fourth aspect of the present invention, in the exhaust pipe sealing device of the first aspect, the axial elastic pressing member is a disc spring. In this case, the annular gap for fitting the disc spring into the annular concave groove can be made relatively small, and the degree of freedom in layout can be increased. In particular, seal rings are provided in multiple stages in the direction of the common axis of both cylindrical ends. Space is relatively easy to use

[0012]

FIG. 1 shows an exhaust pipe sealing apparatus to which the present invention is applied. The exhaust pipe sealing device A is mounted on a connection portion J of a two-part exhaust branch pipe forming an exhaust passage R of an engine (not shown) so as to prevent the exhaust gas G from leaking from the connection portion J to the atmosphere. It is configured. One of the first divided exhaust pipes 1 and the other of the second divided exhaust pipes 2 constituting the exhaust branch pipe are integrally connected at their respective branch branches (not shown) to an engine body (not shown), and are connected to each other. At J, they are inserted and connected without displacement. In the connecting portion J shown in FIG. 1, the exhaust gas G flows from the first divided exhaust pipe 1 to the second divided exhaust pipe 2.

The first divided exhaust pipe 1 has a cylindrical small end 3 at the connecting end.
, And an annular collar 4 following the ring. Small cylindrical end 3
An annular concave groove 5 is formed in the outer wall surface f1, and a seal ring 6 and a backup ring 7 as an axial elastic pressing member are fitted into the annular concave groove 5. The second divided exhaust pipe 2 has a large cylindrical end 8 and a subsequent annular step 9 formed at the connection end. The cylindrical large end 8 has an inner wall surface f2 having an outer wall surface f of the cylindrical small end portion 3.
1 are formed to face each other with a gap t interposed therebetween.

A seal ring 6 fitted in the annular groove 5 is manufactured by casting or the like as a ring having a notch a.
It has a rectangular cross section, and the left and right sides of the rectangular cross section have a common axis L
The outer peripheral edge is formed in an annular plane, and the outer peripheral edge is formed so as to abut the inner wall surface f2 of the large cylindrical end 8. The seal ring 6 is fitted in the annular groove 5 and elastically reduced in diameter so as to abut a pair of butted ends 601, and the outer peripheral edge thereof is in contact with the inner wall surface f 2 of the large cylindrical end 8. Hold. In this state, the outer peripheral edge of the seal ring 6 has the inner wall surface f2 of the cylindrical large end 8.
The elastic restoring force F2 in the radially enlarged direction is applied to the second portion, thereby ensuring the sealing performance of the same portion. It is desirable that the seal ring 6 prevent the tension from being lowered by heat sinking, that is, it is desirable to maintain the elastic displacement characteristics in the radial direction with good durability even in a high-temperature atmosphere. Here, a heat-resistant material such as JIS SUS440B is used as the material.

The backup ring 7 fitted in the annular groove 5 together with the seal ring 6 is compressed and deformed in the direction of the common axis L of the two cylindrical ends 3, 8 of the first divided exhaust pipes 1, 2. And the gap width e between the inner surface of the annular groove 5 and the seal ring 6
Axial pressing force F caused by elastic return
1 is added to the seal ring 6.

The backup ring 7 is a ring having a notch b and is made of the same heat-resistant material as the seal ring 6 by casting or the like. As shown in FIG. 1, the backup ring 7 is manufactured as a ring having an inclined rectangular cross section having left and right side surfaces that maintain a predetermined inclination angle (an angle larger than the angle α in FIG. 1) with respect to a vertical plane of the common axis L. This is a state in which the pair of butting ends 701 and 701 are butted elastically and reduced in diameter, and are further compressed and deformed in the direction of the common axis L.
That is, it is fitted into the annular groove 5 while maintaining a predetermined inclination angle α with respect to the vertical plane of the common axis L. When fitted in the annular groove 5, the backup ring 7 is set so that its outer diameter is close to the inner diameter of the inner wall surface f2 of the large cylindrical end 8. One side end of the outer peripheral edge of the backup ring 7 abuts the seal ring 6 in the annular groove 5, and one side end of the inner peripheral edge abuts one inner wall of the annular groove 5. Presses the seal ring 6 against the other inner wall of the annular groove 5 with an axial pressing force F1 to ensure the sealing performance of the same.

A description will be given of a connecting operation at the connecting portion J of the pair of first and second divided exhaust pipes 1 and 2 using such an exhaust pipe sealing device A. First, the seal ring 6 is fitted into the annular concave groove 5 of the cylindrical small end portion 3 of the first divided exhaust pipe 1, the pair of butted ends 601 and 601 are held in a butted state, and then the backup ring 7 is fitted. And a pair of butted ends 7
01 and 701 are held in a butted state. At this time, the backup ring 7 is compressed and deformed corresponding to the gap width e in the direction of the common axis L, and the seal ring 6 and the annular groove 5 are maintained in a state where the inclined rectangular cross section maintains the inclination angle α with respect to the vertical plane of the common axis L. Is inserted between one of the inner surfaces. Next, the large cylindrical end 8 of the second divided exhaust pipe 2 is fitted to the small cylindrical end 3. At this time, the backup ring 7 and the seal ring 6
Is elastically deformed in the diameter reducing direction, whereby the outer peripheral edges of both rings are fitted into the inner wall surface f2 of the large cylindrical end 8.

After the connecting process at the connecting portion J of the pair of divided exhaust pipes 1 and 2 is completed in this way, the branch side (not shown) of each of the pair of split exhaust pipes 1 and 2 is not shown. It is integrally connected to the engine body side, so that the insertion connection state at the connection portion J is maintained without displacement. In such a connected state, a gap t is secured between the cylindrical large end 8 and the cylindrical small end 3, and the gap t
A longitudinal displacement due to a temperature change of the pair of divided exhaust pipes 1 and 2 can be absorbed.

In such a connecting portion J, the cylindrical large end 8
It is assumed that exhaust gas flows into the annular concave portion 5 through the gap t between the cylindrical small end portion 3. At this time, the seal ring 6 receives the axial pressing force F1 of the backup ring 7 and the exhaust gas pressure P1 on one side surface, and reliably presses the other side surface of the seal ring 6 against the other inner side surface of the annular groove 5. The sealing performance of the same part can be sufficiently ensured. Furthermore, the seal ring 6 has its own elastic return force F2 in the radially expanding direction and the exhaust gas pressure P2 in the radially expanding direction on the bottom wall surface.
The outer peripheral edge of the seal ring 6 to the cylindrical large end 8
The inner wall f2 is pressed against the inner wall f2 to ensure sufficient sealing performance of the same, and it is possible to reliably prevent the exhaust gas from leaking from the connecting portion J. In particular, the sealing ring 6 itself exerts an elastic restoring force F2 that presses against the inner wall surface f2 of the large cylindrical end 8, and the backup ring 7 presses the seal ring 6 against the inner surface of the annular groove 5 in the axial direction. Since F1 is exerted, each pressing force is applied stably, and the backup ring 7 and the seal ring 6
Can be relatively prevented from lowering the tension due to heat, and the sealing force of the seal ring 6 can be maintained with good durability and reliability. The backup ring 7 used in the exhaust pipe sealing device A shown in FIGS. 1 and 2 is a ring having an inclined rectangular cross section having left and right side surfaces that maintains a predetermined inclination angle α. A backup ring 7a as shown may be used.

Here, the backup ring 7a provided at the connecting portion J is formed of the same material as the backup ring 7 of FIG. 1, and has a notch b as shown by a two-dot chain line in FIG. In particular, it is manufactured as a ring having a deformed rectangular cross section in which a concave cut c is formed on the inner peripheral end side. The backup ring 7a is connected to 2 in FIG.
It is displaced from the free state shown by the dashed line to the reduced diameter state shown by the solid line, and at this time, the pair of butting ends 701a, 701a are butted. In particular, when the backup ring 7a is in a free state, its deformed rectangular cross section has left and right sides along the vertical plane of the common axis L, but the concave cut c sets the unbalance of the right and left cross sectional rigidities of this deformed rectangular cross section. Therefore, when it is displaced to a reduced diameter state, the cross-sectional rigidity of the side with the concave cut c (left side in FIG. 4B) is smaller than the opposite side, so that the compression of the concave cut c3 side is performed. The amount of displacement increases, the deformed rectangular section inclines as indicated by the solid line, and the width in the direction of the common axis L increases from B1 to B2.

The width B2 of the deformed rectangular cross section of the backup ring 7a when the diameter is reduced in the free state in the free state is set to be larger than the gap width e1 between one inner surface of the annular groove 5 and the seal ring 6. For this reason, in the set state in which the backup ring 7a is displaced to the reduced diameter state, the width in the direction of the common axis L is compressed to be smaller than B2, and the backup ring 7a is pushed into the annular groove 5 together with the seal ring 6,
a can apply an elastic axial pressing force F1 ′ in the direction of the common axis L to the seal ring 6 at its outer peripheral edge.
When the backup ring 7a as shown in FIG. 3 is used, the same operation and effect as those when the backup ring 7 of FIG. 1 is used can be obtained. In particular, the deformation having the left and right side surfaces along the vertical plane of the common axis L can be obtained. Backup ring 7 with rectangular cross section
1a is easier to manufacture than the backup ring 7 of FIG. 1 which has a slanted rectangular cross section with a slant angle α in a free state.

FIGS. 5A and 5B show a modified example of the backup ring 7a of FIG. Here, the backup ring 7b provided in the connecting portion J has a deformed rectangular cross section in which an inclined notch c1 is formed on the inner peripheral end side, thereby setting an imbalance in left and right cross-sectional rigidities. Also in this case, the backup ring 7b has a smaller cross-sectional stiffness on the side where the inclined notch c1 is located than the opposite side, so that the backup ring 7b is in the free state shown by the solid line.
The deformed rectangular cross section is displaced to the reduced diameter state shown by the two-dot chain line, and the width in the direction of the common axis L increases from B3 to B4.
Also in this case, the backup ring 7b can apply an axial pressing force F1 ', whose outer peripheral edge is elastic, to the seal ring 6, and the same operation and effect as the backup ring 7a of FIG. 3 can be obtained.

The backup ring 7a shown in FIG. 3 has a concave cut c on the inner peripheral side of the deformed rectangular cross section.
Instead, backup rings 7c and 7d having respective deformed rectangular cross sections as shown in FIGS. 6A and 6B may be used. Here, the backup ring 7c shown in FIG. 6A has a deformed rectangular cross section in which a concave cut c2 is formed on the outer peripheral side. In this case, the right side area in the drawing having the concave cut c2 has a lower sectional rigidity than the left side area, the amount of extension deformation on the concave cut c2 side is relatively large, and the deformed rectangular cross section is a solid line from the free state shown by the two-dot chain line. The width in the direction of the common axis L increases from B5 to B6. In this case as well, the backup ring 7c has an outer peripheral edge that provides an elastic axial pressing force F1 ′.
And the same operation and effect as those of the backup ring 7a of FIG. 3 can be obtained.

The backup ring 7d shown in FIG.
Have concave cuts c3 at both inner and outer peripheral sides thereof, and particularly have a deformed rectangular cross section in which the inner concave cut c3 is set to be large. In this case, the cross-sectional rigidity of the left region in the drawing is lower than that of the right region, the amount of compressive displacement around the inner concave cut c3 is large, and the compressive deformation on the side with the concave cut c3 when the diameter is reduced is relatively large. Become
The deformed rectangular cross section is inclined from the free state shown by the two-dot chain line to the reduced diameter state shown by the solid line, and the width in the direction of the common axis L is changed from B7 to B8.
To expand. In this case as well, the backup ring 7d can apply an axial pressing force F1 'whose outer peripheral edge is elastic to the seal ring 6, and the backup ring 7a shown in FIG.
The same operation and effect as described above can be obtained.

The exhaust pipe sealing device A shown in FIG. 1 uses a backup ring 7 or the like as an axial elastic pressing member and applies an axial pressing force F1 or the like to the seal ring 6, but instead of this, 7A, 7B, 8A,
Disc spring 12 and axial wave-shaped annular spring 1 as shown in FIG.
3, the axial pressing force F1 ″ may be applied.
(A), (b) has a large number of slits 121 formed on the inner peripheral edge side thereof, thereby facilitating elastic deformation in the direction of the common axis L (see FIG. 1) and forming a part in the circumferential direction. Notch b
Are formed, and fitting into the annular groove 5 is enabled. 8 (a) and 8 (b) is a wave spring formed in an annular shape with the direction of the common axis L (see FIG. 1) as the amplitude direction, and has elasticity in the direction of the common axis L. Deformation has been facilitated.

The disc spring 12 and the axially wavy annular spring 1
Also in the case where 3 is provided in the connecting portion J, the same operation and effect as the case where the backup ring 7 of FIG. 1 is used can be obtained. In particular, when the disc spring 12 is used, the groove width e2 for mounting the disc spring 12 in the annular concave groove 5 can be made relatively small, and the degree of freedom in layout can be increased.
This is particularly effective when a plurality of annular grooves for fitting the seal ring and the disc spring in the direction of (see FIG. 1) are provided in multiple stages to further enhance the sealing performance. Further, in the case of using the axially wavy annular spring 13, the axial pressing force F1 ″ applied to the seal ring 6 can be continuously applied in the radial direction, and the sealing performance can be further improved.

Although the exhaust pipe sealing device A shown in FIG. 1 has been described as being mounted on the connecting portion J of the two-part exhaust branch pipe, the connecting portion is similarly provided on the other exhaust path constituting piping (not shown). Also in this case, the connecting portion can be provided with the exhaust pipe sealing device to which the present invention is applied, and in this case, the same operation and effect as the exhaust pipe sealing device A of FIG. 1 can be obtained.

[0028]

According to the first aspect of the present invention, the seal ring abuts against the inner wall surface of the large cylindrical end, and the compressively deformed axial elastic pressing member connects the seal ring to the common axial direction of the two cylindrical ends. , And presses against the inner surface of the annular groove, so that it is possible to reliably prevent the exhaust gas from leaking to the atmosphere side through the gap between the inner surface of the annular groove and the seal ring, thereby improving the sealing performance.

According to the second aspect of the present invention, in particular, the seal ring enhances the sealing performance between the inner wall surface of the large cylindrical end and the outer peripheral edge of the seal ring, and the gap between the inner surface of the annular groove and the seal ring is increased. The sealing property of the above is enhanced by the axial elastic pressing member, so that the whole sealing property can be sufficiently improved.

According to the third aspect of the present invention, in particular, a concave notch is formed in the radial section so that the rigidity in the right and left sections is deviated, and when the diameter is reduced, the radial section is inclined in the direction of the common axis so as to be inclined in the same direction. The width of the annular groove is increased, and in this state, it is fitted into the annular gap of the annular groove, so that the axial elastic pressing member can elastically press the seal ring in the common axial direction, and the exhaust gas is sealed with the inner surface of the annular groove. Leakage to the atmosphere side from the annular gap with the ring can be reliably prevented, and sealing performance can be improved.

According to the fourth aspect of the invention, in particular, the clearance for fitting the disc spring into the annular groove can be made relatively small, and the degree of freedom in layout can be increased. When adopting a configuration in which seal rings are provided in multiple stages, it is relatively easy to secure space.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an exhaust pipe sealing device as one embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view of a main part of an exhaust pipe sealing device as another embodiment of the present invention.

4A and 4B show a backup ring used in the exhaust pipe sealing device of FIG. 3, wherein FIG. 4A is a front view and FIG. 4B is a longitudinal sectional view.

5A and 5B show an exhaust pipe sealing device as another embodiment of the present invention, in which FIG. 5A is a sectional view of a main part of the device, and FIG. 5B is a longitudinal sectional view of a backup ring in the device.

FIG. 6 is a cross-sectional view of a main part of a backup ring used in an exhaust pipe sealing device as another embodiment of the present invention;
(A) is a first modification, and (b) is a second modification.

FIGS. 7A and 7B show an exhaust pipe sealing device as another embodiment of the present invention, wherein FIG. 7A is a sectional view of a main part of the device, and FIG. 7B is a front view of a disc spring in the device.

8A and 8B show an exhaust pipe sealing device as another embodiment of the present invention, in which FIG. 8A is a sectional view of a main part of the device, and FIG. 8B is a cutaway front view of an axially annular annular spring in the device. It is.

FIG. 9 is a sectional view of a main part of a conventional exhaust pipe sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st division | segmentation exhaust pipe 2 2nd division | segmentation exhaust pipe 3 cylindrical small end part 5 annular groove 6 seal ring 7 backup ring 8 large cylindrical end f1 outer wall surface of small cylindrical end f2 large cylindrical end Inner wall surface t Clearance A Sealing device for exhaust pipe J Joint L Common axis

Claims (4)

[Claims] 1. A cylindrical small end of the other divided exhaust pipe is inserted into a cylindrical large end of one of the divided exhaust pipes connected to each other, and is inserted into an annular groove on an outer wall surface of the cylindrical small end. An exhaust pipe sealing device in which a seal ring whose outer peripheral edge is in contact with an inner wall surface of a large cylindrical end is fitted to an annular gap between the inner surface of the annular groove and the seal ring. An exhaust pipe sealing device characterized by fitting an axial elastic pressing member elastically compressed and deformed in the axial direction. 2. The exhaust pipe sealing device according to claim 1, wherein the seal ring is formed so as to be elastically deformable in diameter and fitted in the annular groove. 3. The axial elastic pressing member is formed so as to be elastically deformable in diameter and has a concave cut in its radial section to reduce the sectional rigidity. The exhaust pipe sealing device according to claim 1, wherein the exhaust pipe sealing device is fitted in the annular gap while being inclined in a common axis direction. 4. The exhaust pipe sealing device according to claim 1, wherein said axial elastic pressing member is a disc spring.