KR20180101040A - A shork absorbing device inside exhaust system and shork absorbing method the same, restoration method of shork absorbing device - Google Patents

Abstract

The present invention relates to an internal shock absorbing device for an exhaust system, a shock absorbing method by using the same, and a restoration method of the shock absorbing device. More specifically, the present invention relates to the internal shock absorbing device for an exhaust system, a shock absorbing method by using the same, and a restoration method of the shock absorbing device, wherein a shock absorbing device for absorbing shock waves due to internal exhaust gas of the vehicle exhaust system tube is mounted on the internal shock absorbing device so as to reduce a noise and vibration inside the exhaust system tube.

Description

TECHNICAL FIELD [0001] The present invention relates to an internal shock absorbing device for an exhaust system, a shock absorbing method using the shock absorbing device, and a restoring method for a shock absorbing device.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system internal shock absorber, a shock absorbing method using the same, and a method of restoring the shock absorber, and more particularly, to a shock absorber capable of absorbing shock waves To thereby reduce noise and vibration inside the exhaust system pipe, an impact absorption method using the same, and a restoration method of the shock absorption apparatus.

Generally, the engine generates power by burning fuel, and exhausts the exhaust gas generated during combustion through the exhaust pipe.

Exhaust gas discharged through the exhaust pipe includes explosion sound and vibration generated when the engine is burned. To reduce such noise, a muffler is installed at the rear end of the exhaust pipe.

1 shows a muffler of a general exhaust system.

An inlet pipe 4 is formed at one side of the muffler case 2 so as to be connected to the exhaust pipe so as to be a passage through which the exhaust gas flows and a discharge pipe 8 for discharging the exhaust gas to the atmosphere is formed at the other side of the case 2 And a flow pipe 6 for guiding the exhaust gas flowing into the inflow pipe 4 to flow into the discharge pipe 8 is formed in the case 2.

In the muffler, the exhaust gas discharged from the engine flows into the inflow pipe 4, flows in the case 2 while attenuating the noise, and is discharged to the atmosphere through the discharge pipe 8.

However, the muffler having such a configuration has a problem that the shock wave noise of the exhaust gas discharged from the engine can not be effectively attenuated.

In order to solve the above problem, the thickness of the end plate 10 of the muffler case 2 is increased to block the amplification of the shock wave noise or to form the baffle 12 having the perforated hole at the site where the shock wave noise reaches, However, these conventional techniques are not well used because they have insufficient effect to reduce the noise of the exhaust gas shock wave.

Korean Patent Publication No. 10-1996-0039340

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a shock absorbing device capable of absorbing a shock wave due to exhaust gas inside an exhaust system pipe of a vehicle to reduce noise and vibration inside the exhaust system pipe. .

In order to achieve the above object, according to the exhaust system internal shock absorber of the present invention,

And an impact absorbing device for absorbing shock waves due to exhaust gas is mounted inside the exhaust pipe of the vehicle exhaust system.

In the shock absorber,

An outer tubular portion having an inner hollow cylindrical shape and a center hole formed at a center portion of both end surfaces;

An inner tube portion having an inner hollow cylindrical shape, a central hole formed at a center portion of both end surfaces, and an inner tube portion located inside the outer tube portion;

A drive shaft passing through a center hole of the outer tube portion and a center hole of the inner tube portion;

A flow path opening / closing part formed at one end of the exhaust gas inlet side of both ends of the drive shaft;

A stopper formed in a cup shape and having a drive shaft through hole through which the drive shaft passes through the center of the disk, and a stopper located inside the inner tube;

A first spring having a drive shaft as a central axis and located inside the inner tube portion;

A second spring having a drive shaft as a central axis and located inside the outer tube portion;

And a control unit.

And the first spring is located at the rear end of the stopper with respect to the moving direction of the exhaust gas.

And the second spring is located at the rear end of the inner tube portion with respect to the moving direction of the exhaust gas.

And the spring constant of the second spring is larger than the spring constant of the first spring.

And the displacement of the second spring is larger than the displacement of the first spring.

And the inner tube portion is formed to be shorter in length than the axial length of the outer tube portion.

The stopper is fixed to the drive shaft, and the opening of the stopper is located in a direction toward the flow path opening / closing portion.

And a plurality of exhaust gas inflow holes through which the exhaust gas flows are spaced apart from each other by a predetermined distance in a peripheral portion of the stopper.

And a plurality of exhaust gas inflow holes are formed in the disc portion of the stopper at predetermined intervals so as to allow the exhaust gas to flow in the circumferential direction of the drive shaft through hole.

The flow path opening and closing part is characterized by being a cylindrical shape in which the cross-sectional area of one end portion, which is directed from the certain position of the axial length to the drive shaft, gradually decreases.

And a channel opening / closing portion seating portion formed on the outer surface of the front end surface of the inner tube portion, through which the exhaust gas flows, with a predetermined depth in the circumferential direction of the inner tube portion center hole.

The channel opening / closing part seating part is formed in a shape corresponding to one end of the channel opening / closing part, and one end of the channel opening / closing part is seated.

And the shock absorbing device is mounted inside the exhaust pipe located at the front end or the rear end of the muffler in the vehicle exhaust system.

The diameter of the flow path opening / closing portion is smaller than the center hole of the outer tube portion and larger than the center hole of the inner tube portion.

The diameter of the stopper is larger than the center hole of the inner tube portion and smaller than the inner diameter of the inner tube portion.

In order to achieve the above object, according to the present invention, there is provided a shock absorbing method for an internal shock absorbing device for an exhaust system,

The flow of the exhaust gas in the exhaust pipe is in a normal state;

A shock wave arriving at the flow path opening and closing part;

The stopper is pushed to the rear end side of the exhaust pipe while the flow path opening / closing portion is pushed to the rear end side of the exhaust pipe by the shock wave;

Compressing the first spring to the rear end side of the exhaust pipe by movement of the stopper;

Moving the inner tube portion to the rear end side of the exhaust pipe;

Compressing the second spring to the rear end side of the exhaust pipe by movement of the inner pipe portion;

The pressure energy of the shock wave is converted into kinetic energy and is destroyed;

And a control unit.

At the stage where the flow of the exhaust gas in the exhaust pipe is in a normal state,

And the flow path opening / closing portion is located at the front end of the outer tube portion.

At the stage where the flow of the exhaust gas in the exhaust pipe is in a normal state,

And the stopper is configured to abut against the inner surface of the front end surface through which the exhaust gas flows in the both end surfaces of the inner tube portion.

In the step where the first spring is compressed to the rear end side of the exhaust pipe,

And when the one end of the flow path opening / closing part is seated in the flow path opening / closing part seating part of the inner tube part, the compression of the first spring is stopped.

To achieve the above object, there is provided a method for restoring an exhaust system internal shock absorber according to the present invention,

A second spring restoring step, and a first spring restoring step.

In the second spring restoring step, the inner tube portion is pushed to the front end side of the exhaust pipe by the restoration of the second spring.

In the first spring restoring step, the stopper is pushed to the front end side of the exhaust pipe by the restoration of the first spring, so that the opening portion of the stopper contacts the inner surface of the front end face of the inner pipe portion.

According to the present invention, shock waves due to exhaust gas inside the exhaust system pipe are absorbed, thereby reducing the noise and vibration inside the exhaust system pipe.

1 is a muffler of a general exhaust system;
2 is a positional diagram in which a shock absorbing device of the present invention can be mounted in a general exhaust system;
3 is a state view of the shock absorber according to the present invention when vibration is not generated;
Fig. 4 is a state diagram of a shock absorber according to the present invention when a shock wave is generated. Fig.
5 is a state diagram of a shock absorber according to the present invention at the time of shock wave attenuation.
6 is a second spring restoration state after the shock wave disappears in the shock absorber according to the present invention.

For a better understanding of the present invention, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described in detail below. The present embodiments are provided to enable those skilled in the art to more fully understand the present invention. Therefore, the shapes and the like of the elements in the drawings can be exaggeratedly expressed to emphasize a clearer description. It should be noted that the same components are denoted by the same reference numerals in the drawings. Detailed descriptions of well-known functions and constructions which may be unnecessarily obscured by the gist of the present invention are omitted.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system internal shock absorber, a shock absorbing method using the same, and a method of restoring the shock absorber, and more particularly, to a shock absorber capable of absorbing shock waves To thereby reduce noise and vibration inside the exhaust system pipe, an impact absorption method using the same, and a restoration method of the shock absorption apparatus.

FIG. 2 is a view showing a position where a shock absorbing device of the present invention can be mounted in a general exhaust system, FIG. 3 is a state diagram of a shock absorber according to the present invention when vibration is not generated, FIG. 5 is a state diagram of a shock absorber according to the present invention at the time of shock wave attenuation, and FIG. 6 is a sectional view of a shock absorber according to the present invention, FIG.

The shock absorber according to the present invention is mounted in the exhaust pipe 22 of a vehicle exhaust system to absorb shock waves generated in the exhaust system to reduce noise. The shock absorber includes an exhaust pipe 22 located at a front end or a rear end of the muffler 20 .

The shock absorbing device of the present invention for absorbing shock waves in the exhaust system includes an outer tube portion 24, an inner tube portion 28, a drive shaft 36, a flow path switching portion 34, a stopper 38, a first spring 46, And a second spring (48).

The outer tube portion 24 is made of steel or polypropylene and has a cylindrical inner shape with a predetermined length and a center hole 26 into which the drive shaft 36 is inserted do.

The outer tube portion 24 is formed to have a diameter such that the outer circumferential surface of the outer tube portion 24 is in contact with the inner circumferential surface of the exhaust pipe 22 so that the outer tube portion 24 is fixed at a predetermined position inside the exhaust pipe 22. [ Respectively.

The inner tube portion 28 is made of steel and has a cylindrical inner shape with a predetermined length. A central hole 30 is formed at a central portion of both ends to insert the drive shaft 36 therein.

The length of the inner tube portion 28 in the axial direction is shorter than the length of the outer tube portion 24 in the axial direction and the outer circumferential surface of the inner tube portion 28 is formed to have a diameter that is in contact with the inner circumferential surface of the outer tube portion 24, The inner tube portion 28 is located inside the outer tube portion 24.

The inner tube portion 28 is positioned closer to the front end than the rear end of the outer tube portion 24 when the flow in the exhaust pipe 22 is in a steady state.

The inner tube portion 28 is not constrained to the inside of the outer tube portion 24 and the outer tube portion 28 is not in contact with the inner tube portion 28 Has a clearance such that it can move in the longitudinal direction of the inside of the outer tube portion 24.

The driving shaft 36 is longer than the axial length of the outer tube portion 24. The center hole 26 of the outer tube portion 24 and the center hole 30 of the inner tube portion 28 Respectively. That is, the center hole 26 of the outer tube portion 24 and the center hole 30 of the inner tube portion 28 are formed to have the same axis.

An oil passage opening / closing portion 34 is formed at one end of the both ends of the drive shaft 36 on the side where the exhaust gas flows.

The exhaust gas in the exhaust pipe 22 flows from the one end of the drive shaft 36 toward the flow path opening / closing part 34 in the direction toward the other end.

The flow path opening / closing part 34 is made of a rubber material and is formed in a cylindrical shape in which the cross-sectional area of one end portion, which is directed from the fixed axial position to the drive shaft 36, gradually decreases. The diameter of the flow path opening and closing part 34 is smaller than the center hole 26 of the outer tube part 24 and larger than the center hole 30 of the inner tube part 28.

On the outer surface of the front end surface of the inner tube portion 28 through which the exhaust gas flows, a flow path opening and closing portion seating portion 32 having a predetermined shape in the circumferential direction of the inner tube portion central hole 30 is formed . The passage opening / closing part seating part 32 is formed in a shape corresponding to one end of the passage opening / closing part 34, and one end of the passage opening / closing part 34 is seated.

That is, when the shock wave in the exhaust pipe 22 does not reach the shock absorber, exhaust gas in the exhaust pipe 22 flows into the outer pipe portion 24 and the inner pipe portion 28 When the shock wave from the exhaust pipe 22 reaches the shock absorbing device, the shock wave is pushed to the rear end side of the exhaust pipe 22 by the pressure of the shock wave, so that the exhaust gas in the exhaust pipe 22 Is seated in the passage opening and closing part seating part (32) so that it can not flow into the outer tube part (24) and the inner tube part (28).

The stopper 38 is located inside the inner tube portion 28 and is formed into a cup shape so that a drive shaft through hole through which the drive shaft 36 passes is formed at the center of the disk portion 42.

The stopper 38 is fixed at a predetermined position in the longitudinal direction of the drive shaft 36 when the drive shaft 36 passes through the drive shaft through hole and the opening portion of the stopper 38 is connected to the flow passage opening / As shown in FIG.

The diameter of the stopper 38 is larger than the center hole 30 of the inner tube portion 28 and smaller than the inner diameter of the inner tube portion 28 so that when the shock wave does not reach the shock absorber, 38 are in contact with the inner surface of the front end of the inner tube portion 28.

An exhaust gas inflow hole 44 for introducing the exhaust gas at the front end of the outer tube portion 24 into the inner tube portion 28 and the outer tube portion 24 is formed in the disk portion 42 of the stopper 38 And are formed at a plurality of spaced apart intervals in the circumferential direction of the drive shaft through hole.

The exhaust gas inlet holes 44 are also formed in the circumferential portion 40 of the stopper 38 at a predetermined interval in the circumferential direction.

The first spring 46 having the driving shaft 36 as a central axis is provided in the inner tube portion 28.

The first spring 46 is located at the rear end of the stopper 38 with respect to the moving direction of the exhaust gas.

The diameter of the first spring 46 is smaller than the diameter of the disc portion 42 of the stopper 38 and is larger than the diameter of the inner tube portion central hole 30 so that the front end of the first spring 46 Is connected to the outer surface of the disc portion 42 of the stopper 38 and the rear end is connected to the inner surface of the rear end of the inner tube portion 28. That is, the first spring 46 has a displacement in the longitudinal direction of the inner tube portion 28.

The outer tube portion 24 is provided with the second spring 48 having the driving shaft 36 as its central axis.

The second spring 48 is positioned at the rear end of the inner tube portion 28 with respect to the moving direction of the exhaust gas.

The diameter of the second spring 48 is smaller than the inner diameter of the outer tube portion 24 and is larger than the diameter of the outer tube portion central hole 26 and the diameter of the inner tube portion central hole 30, (48) is connected to the outer surface of the rear end of the inner tube portion (28), and the rear end is connected to the inner surface of the rear end portion of the outer tube portion (24). That is, the second spring 48 is displaced in the longitudinal direction of the outer tube portion 24.

The axial length of the second spring 48 is longer than the axial length of the first spring 46 so that the displacement of the second spring 48 is greater than the displacement of the first spring 46, The spring constant of the second spring (48) is made larger than the spring constant of the first spring (46).

In the shock absorbing method of the shock absorbing device of the present invention constructed as described above,

The flow of the exhaust gas in the exhaust pipe (22) is in a normal state;

A shock wave arriving at the flow path opening and closing part (34);

The stopper 38 is pushed to the rear end side of the exhaust pipe 22 by pushing the flow path switching portion 34 to the rear end side of the exhaust pipe 22 by the shock wave;

Compressing the first spring (46) to the rear end side of the exhaust pipe (22) by movement of the stopper (38);

The inner tube portion 28 is moved to the rear end side of the exhaust pipe 22;

Compressing the second spring (48) to the rear end side of the exhaust pipe (22) by movement of the inner tube portion (28);

The pressure energy of the shock wave is converted into kinetic energy and is destroyed;

Lt; / RTI >

When the flow of the exhaust gas in the exhaust pipe 22 is in the normal state, the flow path opening / closing part 34 is located at the front end of the outer tube portion 24, The exhaust gas in the exhaust pipe 22 is in contact with the inner surface of the front end surface of the exhaust pipe 22 on the side where the exhaust gas flows on both ends of the outer pipe portion 24 and the inner pipe portion 28, And flows into the outer tube portion and the inner tube portion 28 through the formed central holes 26 and 30.

When the shock wave reaches the flow path switching part 34 and enters the inside of the shock absorbing device, the flow path switching part 34 and the drive shaft 36 are connected to the exhaust pipe 22 by the shock wave, The stopper 38 is pushed to the rear end side of the exhaust pipe 22. As shown in Fig.

The first spring 46 is compressed to the rear end side of the exhaust pipe 22 by the movement of the stopper 38 so that the flow path opening and closing part 34 is completely pushed and the one end of the flow path opening / The center holes 26 and 30 formed in the front end surfaces of the outer tube portion 24 and the inner tube portion 28 are closed so that the outer tube portion 24 and the inner tube portion 28, The inflow of the exhaust gas into the inside of the tube portion 28 is stopped and the compression of the first spring 46 is stopped.

When the first spring 46 is completely compressed, the inner tube portion 28 is pushed toward the rear end side of the exhaust pipe 22 by the exhaust gas flowing from the front end to the rear end side of the shock absorbing device.

The second spring 48 is compressed to the rear end side of the exhaust pipe 22 by the movement of the inner tube portion 28 and the pressure energy of the shock wave is converted into kinetic energy while the second spring 48 is compressed, 22), and the noise is reduced due to the reduction of the discharge pressure at the end of the exhaust pipe (22).

After the disappearance of the shock wave, the shock absorber is restored to the state of the shock absorber when the flow of the exhaust gas in the exhaust pipe (22) is in the steady state.

Wherein the step of restoring the shock absorbing device comprises:

Restoring the second spring (48);

Restoring the first spring (46);

Lt; / RTI >

The second spring 48 is more restored than the first spring 46 because the spring constant of the second spring 48 is larger than the spring constant of the first spring 46.

The inner spring tube 28 is pushed to the front end side of the exhaust pipe 22 while the second spring 48 is restored in the restoring step of the second spring 48. When the second spring 48 is completely restored The restoration of the first spring 46 is started.

The stopper 38 is pushed to the front end side of the exhaust pipe 22 while the first spring 46 is restored in the restoring step of the first spring 46, The restoration of the first spring 46 is completed and the shock absorber is restored to the initial state.

That is, the shock absorbing step and the restoring step of the shock absorbing device are repeated within a relatively short period of time, so that the pressure energy of the high pressure in the exhaust pipe 22 is dissipated as kinetic energy to reduce vibration and noise.

It is possible to adjust the size of the center hole 26 of the outer tube portion 24 and the center hole 30 of the inner tube portion 28 which are the paths of the exhaust gas or the spring constant of the first and second springs 46 and 48 It is possible to realize differentiated sound quality in each region through exhaust noise / humming noise reduction and intake / exhaust system control.

The embodiments of the exhaust system internal shock absorber of the present invention, the shock absorption method using the same, and the method of restoring the shock absorber according to the present invention described above are merely exemplary and those skilled in the art will appreciate that various modifications, It will be appreciated that various modifications and equivalent embodiments are possible. It is therefore to be understood that the invention is not limited to the form set forth in the foregoing description. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

2: Conventional muffler case
4: Conventional inlet pipe
6: Conventional flow tube
8: Conventional discharge pipe
10: Conventional end plate
12: Conventional baffle
14: Exhaust manifold
16: catalytic converter
18: Resonator
20: muffler
22: Exhaust pipe
24:
26: outer tube center hole
28: Inner tube
30: Inner tube center hole
32: Euro opening / closing part seating part
34:
36: drive shaft
38: Stopper
40: Peripheral portion of the stopper
42: disc portion of the stopper
44: Exhaust gas inlet hole
46: first spring
48: Second spring

Claims (23)

Inside the exhaust pipe of a vehicle exhaust system, a shock absorbing device for absorbing shock waves due to exhaust gas is mounted
Wherein the internal shock absorbing device comprises: The method according to claim 1,
The shock absorber (1)
An outer tubular portion having an inner hollow cylindrical shape and a center hole formed at a center portion of both end surfaces;
An inner tube portion having a cylindrical inner shape with a predetermined constant length, a center hole formed at a center portion of both end surfaces, and located inside the outer tube portion;
A drive shaft passing through a center hole of the outer tube portion and a center hole of the inner tube portion;
A flow path opening / closing unit formed at one end of the exhaust pipe at one end of the drive shaft;
A stopper formed in a cup shape and having a drive shaft through hole through which the drive shaft passes, the stopper being positioned inside the inner tube;
A first spring having the driving shaft as a central axis and located inside the inner tube portion;
A second spring having the driving shaft as a central axis and located inside the outer tube portion;
And an internal combustion engine. 3. The method of claim 2,
Wherein the first spring is located at a rear end of the stopper with respect to a moving direction of the exhaust gas. The method of claim 3,
Wherein the second spring is located at a rear end of the inner tube portion with respect to a moving direction of the exhaust gas. 5. The method of claim 4,
Wherein a spring constant of the second spring is larger than a spring constant of the first spring. 6. The method of claim 5,
And the displacement of the second spring is larger than the displacement of the first spring. 3. The method of claim 2,
Wherein the inner tube portion is formed to be shorter in length than the axial length of the outer tube portion. The method of claim 3,
Wherein the stopper is fixed to the drive shaft, and the opening portion of the stopper is positioned in a direction toward the flow path opening / closing portion. 9. The method of claim 8,
Wherein a plurality of exhaust gas inflow holes through which exhaust gas flows are spaced apart from each other at a predetermined interval are formed in the periphery of the stopper. 9. The method of claim 8,
Wherein a plurality of exhaust gas inflow holes through which exhaust gas flows in the circumferential direction of the drive shaft through hole are formed in the disc portion of the stopper at a predetermined interval. 3. The method of claim 2,
Wherein the flow path opening / closing portion is in the shape of a cylinder in which a cross-sectional area of one end portion, which is directed from the certain position of the axial length to the drive shaft, gradually decreases. 12. The method of claim 11,
Wherein an outer surface of a front end surface of the inner tube portion through which exhaust gas flows is formed with a passage opening / closing portion seating portion having a predetermined depth in a circumferential direction of the inner tube portion center hole. 13. The method of claim 12,
Wherein the passage opening / closing part seating part is formed in a shape corresponding to one end of the passage opening / closing part, and one end of the passage opening / closing part is seated. The method according to claim 1,
Wherein the shock absorbing device is mounted in the exhaust pipe located at the front end or the rear end of the muffler in the vehicle exhaust system. 3. The method of claim 2,
Wherein the diameter of the passage opening and closing part is smaller than the center hole of the outer tube part and larger than the center hole of the inner tube part. 3. The method of claim 2,
Wherein a diameter of the stopper is larger than a center hole of the inner tube portion and smaller than an inner diameter of the inner tube portion. 18. A shock absorption method for a shock absorber according to any one of claims 1 to 16,
The flow of the exhaust gas in the exhaust pipe is in a normal state;
A shock wave arriving at the flow path opening and closing part;
The stopper is pushed to the rear end side of the exhaust pipe while the flow path opening / closing portion is pushed to the rear end side of the exhaust pipe by the shock wave;
Compressing the first spring to the rear end side of the exhaust pipe by movement of the stopper;
Moving the inner tube portion to the rear end side of the exhaust pipe;
Compressing the second spring to the rear end side of the exhaust pipe by movement of the inner pipe portion;
The pressure energy of the shock wave is converted into kinetic energy and is destroyed;
And an exhaust pipe connected to the exhaust pipe. 18. The method of claim 17,
In the stage where the flow of the exhaust gas in the exhaust pipe is in a normal state,
Wherein the flow path opening / closing portion is located at an upstream side of a front end surface of the outer tube portion. 18. The method of claim 17,
In the stage where the flow of the exhaust gas in the exhaust pipe is in a normal state,
Wherein the stopper is configured to abut on an inner surface of a front end face of the inner tube portion through which exhaust gas flows in both end faces. 18. The method of claim 17,
In the step of compressing the first spring toward the rear end side of the exhaust pipe,
Wherein the compression of the first spring is stopped when one end of the flow path opening / closing part is seated in the flow path opening / closing part seating part of the inner tube part. A method for restoring a shock absorbing device after an impact absorbing method of an exhaust system internal shock absorbing device of claim 17,
A second spring restoring step;
A first spring restoring step;
Wherein the first and second shock absorbers are disposed on the inner surface of the body. 22. The method of claim 21,
Wherein the inner tube portion is pushed to the front end side of the exhaust pipe by the restoration of the second spring in the second spring restoring step. 22. The method of claim 21,
Wherein the stopper is pushed to the front end side of the exhaust pipe by the restoration of the first spring in the first spring restoring step so that the opening portion of the stopper abuts the inner surface of the front end face of the inner pipe portion. How to restore.

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