JP3668954B2 - Flexible tube for automobile exhaust system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a flexible tube for an automobile exhaust system that is provided in the middle of an exhaust pipe from an engine and absorbs engine vibration and running vibration.
[0002]
[Prior art]
Conventionally, as a flexible tube for an automobile exhaust system, for example, those described in Japanese Utility Model Publication No. 63-47613 and Japanese Utility Model Publication No. 3-55778 are known.
[0003]
These conventional sources describe an outer blade 101 provided to cover the outer periphery of the bellows 100, as shown in FIG.
[0004]
As shown in FIG. 8, the outer blades 101 described in these conventional sources are each provided with a plurality of thin metal wire rods (stainless wire rods) and arranged side by side so that adjacent metal wire rods are in contact with each other. Thus, the band-shaped wire bundle 102 is formed into one set, and a plurality of sets of band-shaped wire bundles 102 required per round are knitted in an oblique direction to form a cylindrical shape.
[0005]
Thus, the outer blade 101 formed in the shape of a knitted mellia has an appropriate stretchability. Therefore, the outer blade 101 is provided so as to cover the outer periphery of the bellows 100, thereby protecting the bellows 100 from foreign substances and preventing the expansion. doing.
[0006]
In the outer blade 101, when the band-shaped wire bundle 102 is knitted, as shown in FIG. 8, the portions where the ends of the respective wire bundles 102 overlap with each other become slightly space so that the four wire bundles 102 An enclosed minute opening 103 is formed.
[0007]
[Problems to be solved by the invention]
However, the conventional outer blade 101 usually has a minute opening 103 having a very small opening area as a result of densely braiding the wire bundle 102, and is not particularly perceived as an opening. .
[0008]
In the automotive exhaust system flexible tube having such an outer blade 101, it is difficult for snowmelt salt from the outside to enter the bellows 100. However, once the snowmelt salt enters the inside, it is not discharged to the outside. The space between the bellows 100 and the outer blade 101 becomes an environment with a high salinity concentration due to the internal accumulation of snow melting salt, causing a problem of high temperature salt damage corrosion.
[0009]
That is, the band-shaped wire bundle 102 constituting the outer blade 101 is a band-shaped metal wire having a thin wire diameter, and the band-shaped wire bundle is alternately knitted so that it can be crushed during traveling. When the outer blade 101 expands and contracts to absorb the vibration displacement applied to the exhaust pipe, gaps are formed between the adjacent metal wire rods or overlapping portions of the band-like wire bundles, and the gaps are closed. The minute opening 103 surrounded by the bundle 102 expands or contracts. Therefore, no matter how densely the band-shaped wire bundle is knitted, the infiltration of the snow melting salt cannot be reliably prevented. Moreover, the snowmelt water containing salt enters into the outer blade 101 at any time when the gap is formed or by capillary action. Then, the snow melting salt that has infiltrated adheres to the surface of the bellows 100 and the inner surface of the outer blade 101, and then the salt is precipitated by evaporation of water, or the snow melting salt dries and accompanies deformation of the bellows 100 and outer blade 101. Even if it becomes a dry salt lump and peels off from the surface, it remains in the space between the bellows 100 and the outer blade 101.
[0010]
On the other hand, since the bellows 100 is made of stainless steel, it has durability to a high temperature environment and corrosion resistance to salt under a single condition, but both conditions are high in an exhaust heat + high salt concentration environment where both conditions are added. It leads to salt damage corrosion. That is, when the bellows 100 is subjected to high temperature heat effects due to the exhaust heat for a long time, the chromium of the stainless steel combines with the carbon and the chromium content of the stainless steel decreases, so that sodium chloride or the like enters the gap in which the chromium is reduced. Corroded by the mechanism. In other words, the chromium content of the stainless steel material is reduced and becomes closer to the iron material, which is easily corroded.
[0011]
Therefore, in the conventional flexible tube using the tightly knitted outer bellows 101, when considering the reduction of the plate thickness due to high temperature salt damage corrosion, the plate thickness of the bellows 100 must be set sufficiently thick, In order to exhibit the expansion / contraction displacement absorption performance, which is the required performance of the bellows 100, the spring constant is kept low by increasing the number of peaks.
[0012]
Incidentally, FIG. 7 shows an example of a flexible tube using a conventional tightly knitted outer bellows 101.
[0013]
This flexible tube is constructed by using a bellows 100 made of a two-layered product in which two 0.3 mm-thick stainless steel plates are overlapped, and set to 28 peaks by bending, with a load of 14 kgf or less. A spring constant in the pulling direction in which a displacement of 10 mm is obtained is achieved. As a result, although the expansion / contraction displacement absorbing performance, which is the required performance of the bellows 100, can be exhibited, there is a problem that the total length L2 of the flexible tube becomes approximately 270 mm, resulting in an increase in size.
[0014]
The problems to be solved by the present invention are listed below.
[0015]
Challenge 1, in the flexible tube for an automobile exhaust system having an outer blade configured by knitting bellows and thin metal wire which absorbs expansion and contraction displacement, to reduce the high temperature salt corrosion of the bellows to the stainless steel as a raw material, the high temperature salt damage It is an object of the present invention to provide a flexible tube that is greatly reduced in size while satisfying the required performance of absorption of expansion and contraction displacement by the bellows by reducing the thickness reduction due to corrosion and setting the sheet thickness of the bellows thin .
[0016]
Problem 2 is to provide a flexible tube whose overall length is less than half that of a conventional flexible tube.
[0017]
[Means for Solving the Problems]
(Solution 1)
Solution 1 (Claim 1) of Problem 1 covers a bellows that absorbs expansion / contraction displacements of exhaust pipes connected to both ends, and covers the outer periphery of the bellows in order to protect the bellows and prevent extension. In an automotive exhaust system flexible tube provided with an outer blade provided,
A set of band-shaped wire bundles of a plurality of metal wires having thin wire diameters arranged side by side is formed into one set, and a plurality of sets of band-shaped wire bundles required per one turn are knitted obliquely into a cylindrical shape, and in four directions. A portion surrounded by the side end of the band-shaped wire bundle to be knitted is an opening, and the total opening area of a large number of openings formed over the entire outer blade is in the range of 20% to 50% with respect to the total surface area of the outer blade. An outer blade set to
A bellows made of a stainless steel material, having a number of ridges of 15 or less, and a plate thickness having a spring constant in a pulling direction in which a displacement of 10 mm can be obtained with a load of 14 kgf or less,
It is characterized by comprising in combination.
[0018]
The operation will be described.
[0019]
When traveling on a snowy road where snow melting salt is sprayed, the snow melting salt enters the inside through a large number of openings formed in the outer blade. However, the snow-melting salt that has infiltrated adheres to the surface of the bellows and the inner surface of the outer blade, and then the snow-melting salt containing moisture is dried by the exhaust heat and becomes a small lump as the bellows and outer blade are deformed. When peeled off, the dried salt lump is discharged to the outside from the opening of the outer blade, and the salt lump is not accumulated in the space between the bellows and the outer blade.
[0020]
Therefore, the bellows made of stainless steel is not exposed to an environment with a high salt concentration, and the high temperature salt corrosion of the bellows is reduced as much as the salt concentration is kept low.
[0021]
As a result, in setting the plate thickness of the bellows, the use of an outer blade having an opening reduces the reduction in plate thickness due to high-temperature salt damage corrosion, so that the plate thickness of the bellows can be set thinner than before. And with this thin plate setting, the spring constant of the bellows becomes low, and even if the number of peaks is less than that of the conventional bellows, the spring constant of a size that exhibits the absorbing performance of expansion and contraction displacement that is the required performance of the bellows is maintained. be able to.
[0022]
Therefore, by combining an outer blade having an opening and a bellows set to a plate thickness having a spring constant in the pulling direction in which the number of ridges is 15 or less and the load is 14 kgf or less and a displacement of 10 mm is obtained. Thus, the flexible tube can be greatly reduced in size while satisfying the required performance of absorption of expansion and contraction displacement by the bellows.
[0023]
(Solution 2)
The solution 2 (Claim 2) of the problem 2 is the flexible tube for an automobile exhaust system according to Claim 1,
The bellows is a two-layer product in which two stainless steel plates having a thickness of 0.2 mm are overlapped, and the number of peaks is set to 9 by bending.
[0024]
Explaining the operation, the conventional bellows is made of a two-layer product in which two 0.3 mm-thick stainless steel plates are overlapped, and the number of 28 peaks is set by bending, and the total length L2 is about 270 mm. On the other hand, the two-layer product made by superimposing two 0.2 mm thick stainless steel plate materials, and the number of nine ridges set by bending, the total length L1 is about 105 mm, and the total length of the bellows Is reduced to less than half (about 2/5). In addition, the distance between the peaks of both flexible tubes and the diameter of the cylindrical portions at both ends are the same.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
First, the configuration will be described.
[0026]
FIG. 1 is a half sectional view showing a flexible tube for an automobile exhaust system according to a first embodiment corresponding to the first and second aspects of the invention. FIG. 2 is an outer blade of the flexible tube for an automobile exhaust system according to the first embodiment. FIG. 3 is a side view showing a bellows of the flexible tube for an automobile exhaust system according to the first embodiment, and FIG. 4 is an enlarged sectional view of a portion A in FIG. 3 showing the bellows.
[0027]
In FIG. 1, F is a flexible tube, 1 is a bellows, 2 is an outer blade, and 3 is a protector.
[0028]
The bellows 1 is provided for the purpose of absorbing expansion / contraction displacement when exhaust pipes (not shown) are connected to both ends of the bellows 1 and both exhaust pipes are expanded / contracted due to engine vibration or running vibration.
[0029]
As shown in FIGS. 3 and 4, the bellows 1 in the first embodiment is made of a multilayer product in which two layers of austenitic stainless steel plates having a thickness of 0.2 mm are stacked, and this is bent into nine peaks. Manufactured by setting the number of peaks 1a and the cylindrical portions 1b on both sides. The five ridges 1a in the central part have a constant outer diameter, but the two ridges 1a on both sides are set so that the outer diameter increases stepwise from the cylindrical part 1b.
[0030]
The outer blade 2 is intended to protect the bellows 1 and prevent it from extending completely, and is provided so as to cover the outer periphery of the bellows 1.
[0031]
As shown in FIG. 2, the outer blade 2 is a set of band-like ones prepared by preparing a plurality of thin stainless steel wire rods and arranging them side by side so that the adjacent stainless steel wire materials are in contact with each other. A plurality of sets of band-shaped wire bundles 2a required per circumference are knitted in an oblique direction to form a cylindrical shape, and a portion surrounded by the side ends of the band-shaped wire bundle 2a knitted in four directions is defined as an opening portion 4. A total opening area of a large number of openings 4 formed over the entire blade 2 is set to be in a range of 20% to 30% with respect to the total surface area of the outer blade 2.
[0032]
In the outer blade 2 in the first embodiment, the number of sets of the band-shaped wire bundle 2a per round is 48 sets (the number of sets of the conventional outer blade per round is 48 sets, and there is no change). The wire diameter of the stainless steel wire constituting the bundle 2a is 0.4 mm (the wire diameter of the conventional outer blade is 0.4 mm and is not changed), the number of the stainless steel wire constituting the band-like wire bundle 2a is 10 and the opening The area of each opening 4 corresponds to a hole having a diameter of 2 mm to 4 mm by reducing the number (14) which is set by a conventional outer blade that is knitted densely with almost no part 4. The total opening area obtained by adding the opening areas of the respective openings 4 is set to be in a range of 20% to 30% with respect to the total surface area of the outer blade 2.
[0033]
The protector 3 protects both ends of the bellows 1 and fixes the outer blade 2, and is provided by spot welding (spot welded portion 5) on both ends of the bellows 1 and the outer blade 2.
[0034]
Next, the operation will be described.
[0035]
[Aperture setting action to outer blade 2]
The braiding interval of the band-shaped wire bundle 2a does not change by not changing the number of groups (48 sets) per circumference of the band-shaped wire bundle 2a of the outer blade 2.
[0036]
Further, the wire diameter (0.4 mm) of the stainless wire constituting the band-like wire bundle 2a is not changed, the number of the stainless wire is set to 10, and the outer blade that is tightly knitted with almost no opening is set. By making the number smaller than the number (14), the width of the band-shaped wire bundle 2a becomes narrower by the smaller number.
[0037]
Therefore, the portion surrounded by the side ends of the band-shaped wire bundle 2a knitted in four directions by a simple method that does not change the manufacturing method of the conventional outer blade only by reducing the number of stainless wire materials is shown in FIG. As shown, an opening 4 is formed.
[0038]
[Snow-melting salt elimination effect by opening]
During traveling on a snowy road where snow melting salt is dispersed, the snow melting salt enters the inside through the openings 4 formed in the outer blade 2.
[0039]
The snow melting salt that has infiltrated adheres to the surface of the bellows 1 and the inner surface of the outer blade 2, and then the snow melting salt containing moisture is dried by exhaust heat and adheres as a lump of crystalline salt.
[0040]
However, when a small salt lump is formed along with the expansion and contraction of the bellows 1 or the outer blade 2 and peels off from the surface of the bellows 1 or the inner surface of the outer blade 2, the dried salt lump is externally exposed from the opening 4 of the outer blade 2. The salt lump is not accumulated in the space between the bellows 1 and the outer blade 2.
[0041]
Accordingly, the bellows 1 is not exposed to a high salt concentration environment, and the high temperature salt corrosion of the bellows 1 is reduced as much as the salt concentration is kept low.
[0042]
Incidentally, the result of the high temperature salt damage corrosion test conducted by the present inventor is shown in FIG.
[0043]
The target product of this test is a combination of the same bellows made of a multilayer product made of two austenitic stainless steel plates with a thickness of 0.3 mm, combined with a conventional outer blade with a dense knitting method with few openings. The flexible tube according to the first embodiment is a combination of a conventional flexible tube and an outer blade having an opening 4 formed therein.
[0044]
The test method is immersion in saturated aqueous sodium chloride solution → high temperature heating (550 ° C or higher) → cooling in one cycle, artificially creating conditions for high temperature salt damage corrosion (intergranular corrosion environment), and repeating this, Measure the thickness reduction rate.
[0045]
As a result of the high temperature salt damage corrosion test, as shown in FIG. 5, in the case of the flexible tube using the outer blade by the knitting method of the first embodiment, the bellows plate with respect to the flexible tube using the outer blade by the conventional knitting method It was confirmed that the thickness reduction rate was greatly reduced.
[0046]
This proves that when the outer blade by the knitting method of the first embodiment is used, it is superior in high temperature salt damage corrosion resistance.
[0047]
[Compact flexible tube]
In setting the plate thickness of the bellows 1, as described above, when the outer blade 2 having the opening 4 is adopted, it is superior in high-temperature salt damage corrosion, and the reduction in plate thickness due to high-temperature salt damage corrosion is reduced. The plate | board thickness of the bellows 1 can be set thinner than before. And with this thin plate setting, the spring constant of the bellows 1 is lowered, and even if the number of peaks is less than that of the conventional bellows, the spring constant of a size that exhibits the absorbing performance of the expansion and contraction displacement that is the required performance of the bellows is maintained. can do.
[0048]
This means that by adopting a bellows having a smaller number of peaks than the conventional bellows, the flexible tube can be made compact while satisfying the required performance of absorption of expansion / contraction displacement by the bellows.
[0049]
Incidentally, FIG. 6 shows the results of a bellows tensile direction spring constant test conducted by the present inventors.
[0050]
The target products of this test are bellows made of a two-layered austenitic stainless steel plate having a thickness of 0.3 mm, with 28, 21, and 27 mountains, and austenitic stainless steel having a thickness of 0.2 mm. A bellows made of a two-layer product made of a plate material having nine, 12, and 15 mountains was used. In the test method, one end of each bellows was fixed, a load in the pulling direction was applied from the other end, and the elongation displacement of the bellows and the applied load were measured.
[0051]
As a result of the bellows spring constant test, in the case of a bellows made of a two-layer product having a thickness of 0.3 mm, only the 28 peaks are below the required spring constant level (the spring constant at which a displacement of 10 mm can be obtained when the load is 14 kgf or less). However, in the case of 21 peaks and 27 peaks, it becomes higher than the required spring constant level.
[0052]
On the other hand, in the case of a bellows made of a two-layer product having a thickness of 0.2 mm, any of 9 peaks, 12 peaks, and 15 peaks is below the required spring constant level.
[0053]
Therefore, by combining the outer blade 2 having the opening 4 and the bellows 1 made of a two-layer product obtained by superimposing two 0.2 mm-thick stainless steel plates, the number of peaks is nine by bending. The flexible tube F was greatly downsized while satisfying the required performance of absorbing expansion and contraction by the bellows 1. Specifically, the conventional bellows shown in FIG. 7 which is made of a two-layer product in which two 0.3 mm-thick stainless steel plates are overlapped and set to 28 crests by bending, has a total length L2 of approximately 270 mm. On the other hand, the bellows 1 of this application shown in FIG. 1, which is made of a two-layer product obtained by superimposing two 0.2 mm-thick stainless steel plates and set to a number of nine peaks by bending, has a total length L1 of approximately 1. The overall length of the bellows 1 was reduced to less than half (about 2/5) compared to the conventional one. In addition, the distance between the peaks of both flexible tubes and the diameter of the cylindrical portions at both ends are the same.
[0054]
Next, the effect will be described.
[0055]
(1) A plurality of sets of band-shaped wire bundles 2a required per one circle are knitted in an oblique direction to form a cylindrical shape, and a portion surrounded by a side end of the band-shaped wire bundle 2a knitted in four directions is an opening 4 And the outer blade 2 set so that the total opening area of the openings 4 formed over the entire outer blade 2 is in the range of 20% to 30% with respect to the total surface area of the outer blade 2, and the thickness 0 .Because a multi-layer product made of two layers of 2 mm austenitic stainless steel plate is used as a raw material, and this is combined with a bellows 1 having nine peaks by bending, a flexible tube F is constructed. While satisfying the required performance, the flexible chain has been greatly reduced in size by less than half the total length of conventional flexible tubes. It can provide over blanking F.
[0056]
(2) The number of sets per round of the band-shaped wire bundle 2a and the wire diameter of the stainless wire constituting the band-shaped wire bundle 2a are not changed, and the number of stainless wire is closely knitted with almost no opening. Since the outer blade 2 is configured by reducing the number of the outer blades to be set by the outer blade, the opening 4 is formed in the outer blade 2 by a simple method of reducing the number of stainless steel wires constituting the band-shaped wire bundle 2a. Can be set.
[0057]
(3) Since the opening 4 is formed in the outer blade 2, the degree of freedom of movement of the band-shaped wire bundle 2a is increased and the spring constant of the outer blade 2 can be reduced compared to the conventional tightly knitted outer blade. it can.
[0058]
As a result, the vibration absorption performance in the blade displacement region (region where the load and displacement amount is larger than the bellows displacement region) of the flexible tube F in which the outer blade 2 having the opening 4 is used is improved. This is preferable in terms of durability and sound vibration.
[0059]
(4) Since both the bellows 1 and the outer blade 2 are smaller than the conventional flexible tube, the usage amount of the stainless steel double layer plate material that is the material of the bellows 1 and the stainless wire material that is the material of the outer blade 2 is reduced. The cost of the flexible tube F can be reduced.
[0060]
(Other embodiments)
In the first embodiment, an example of the bellows 1 having a number of nine peaks formed by bending a multi-layer product in which two layers of 0.2 mm thick austenitic stainless steel plates are stacked is shown. Is a bellows set to a plate thickness having a spring constant in the pulling direction in which a displacement of 10 mm is obtained with a load of 14 kgf or less and a load of 14 kgf or less. For example, a two-layer product having a thickness of 0.2 mm shown in FIG.
[0061]
In the first embodiment, the number of sets of stainless wire is set with an outer blade that is tightly knitted with almost no opening, without changing the number of pairs of wire bundles 2a per circumference and the wire diameter of the stainless wire. Although the example in which the opening 4 is formed by reducing the number of stainless steel wires to be formed is shown, the number of sets of metal wire rods and the number of sets of metal wire rods per turn of the band-like wire bundles are not changed. You may make it form an opening part by making a wire diameter thinner than the wire diameter of the metal wire set with the outer blade knitted densely with few openings. Further, among the number of pairs of band-shaped wire bundles, the number of metal wires, and the wire diameter of the metal wire, the number of sets per turn of the band-shaped wire bundle is reduced to form the opening. Alternatively, the opening may be formed by selecting and changing two or all three of the number of sets, the number of wires, and the wire diameter.
[0062]
In the first embodiment, the total opening area of the opening 4 is set to a range of 20% to 30% with respect to the total surface area of the outer blade 2. Any material that is set within the range of 20% (lower limit considering the salt lump discharging function) to 50% (upper limit considering the bellows protecting function) relative to the surface area is included in the present invention.
[0063]
In the first embodiment, a flexible tube having no inner blade is shown inside the bellows 1, but an outer blade having an opening of the present application is provided on a flexible tube in which an inner blade, an inner pipe, or the like is provided inside the bellows. It can also be applied.
[0064]
【The invention's effect】
In the invention according to claim 1, in the flexible tube for an automobile exhaust system having an outer blade constructed by knitting a bellows that absorbs expansion and contraction displacement and a thin metal wire, the outer blade is a metal wire having a thin wire diameter. A set of band-like wire bundles bundled side by side, and a plurality of sets of band-like wire bundles required per round are knitted in an oblique direction into a cylindrical shape, and a band-like wire bundle knitted in four directions An outer blade in which a portion surrounded by the side edges of the outer blade is used as an opening, and a total opening area of a large number of openings formed over the entire outer blade is set in a range of 20% to 50% with respect to the total surface area of the outer blade; the stainless steel is a material, the number of ridges is not more than 15 mountains, and, lifting the direction of the spring constant tension a load is obtained 10mm displacement below 14kgf Since the structure and the bellows which is set to the plate thickness, by a combination of, possible to reduce the hot salt corrosion of the bellows to the stainless steel as a material, to reduce the sheet thickness reduction by hot salt corrosion, set thinner the thickness of the bellows Thus, there is an effect that it is possible to provide a flexible tube that is greatly reduced in size while satisfying the required performance of absorption of expansion and contraction by the bellows.
[0065]
According to a second aspect of the present invention, in the flexible tube for an automobile exhaust system according to the first aspect, the bellows is made of a two-layered product in which two stainless steel plates having a thickness of 0.2 mm are stacked, and is bent. Accordingly, the flexible tube having a total length of half or less compared to the conventional flexible tube can be provided while satisfying the required performance of absorbing the expansion and contraction displacement by the bellows.
[0066]
In addition, since the total length of the flexible tube is significantly shortened, restrictions on the exhaust system design are reduced, and the degree of design freedom is increased.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing a flexible tube for an automobile exhaust system according to a first embodiment of the present invention.
FIG. 2 is a partially enlarged view showing an outer blade of the flexible tube according to the first embodiment.
FIG. 3 is a side view showing a bellows of the flexible tube of the first embodiment.
4 is a cross-sectional view of the bellows of FIG. 3A according to Embodiment 1. FIG.
5 is a high temperature salt damage corrosion test result diagram of the flexible tube of Embodiment 1 and a flexible tube using a conventional tightly knitted outer blade. FIG.
FIG. 6 is a comparison diagram of spring constant characteristics measured by varying the bellows thickness and the number of peaks.
FIG. 7 is a half cross-sectional view showing a conventional automotive exhaust system flexible tube.
FIG. 8 is a partially enlarged view showing an outer blade of a conventional flexible tube for an automobile exhaust system.
[Explanation of symbols]
F Flexible tube 1 Bellows 1a Mountain part 1b Cylindrical part 2 Outer blade 2a Band-shaped wire bundle 3 Protector 4 Opening part

Claims (2)

An automotive exhaust system comprising a bellows that absorbs expansion / contraction displacement of an exhaust pipe connected to both ends, and an outer blade that is provided so as to cover the outer periphery of the bellows in order to protect the bellows and prevent it from extending completely In flexible tubes,
A set of band-shaped wire bundles of a plurality of metal wires having thin wire diameters arranged side by side is formed into one set, and a plurality of sets of band-shaped wire bundles required per one turn are knitted obliquely into a cylindrical shape, and in four directions. A portion surrounded by the side end of the band-shaped wire bundle to be knitted is an opening, and the total opening area of a large number of openings formed over the entire outer blade is in the range of 20% to 50% with respect to the total surface area of the outer blade. An outer blade set to
A bellows made of a stainless steel material, having a number of ridges of 15 or less, and a plate thickness having a spring constant in a pulling direction in which a displacement of 10 mm can be obtained with a load of 14 kgf or less,
A flexible tube for an automobile exhaust system, characterized by comprising a combination of the above. The flexible tube for an automobile exhaust system according to claim 1,
A flexible tube for an automobile exhaust system, characterized in that the bellows is made of a two-layer product in which two stainless steel plates having a thickness of 0.2 mm are overlapped, and the number of peaks is nine by bending.

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