JP4445102B2 - Exhaust pipe and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method and a pipe for an exhaust system double pipe that is doubled with a heat insulating material interposed in order to prevent heating and noise caused by exhaust of automobiles, motorcycles, and the like.
[0002]
[Prior art]
Conventionally, in order to prevent heating and noise caused by exhaust from automobiles, motorcycles, etc., an exhaust system double pipe that has a double structure with inner and outer pipes, and an exhaust system double pipe that has a heat insulating material interposed between the inner and outer pipes Etc. are provided. For example, Japanese Patent Laid-Open No. 51-8160 discloses an exhaust system double pipe having a double structure with the above inner and outer pipes. Further, for example, an exhaust system double pipe in which a heat insulating material is interposed between the inner and outer pipes is disclosed in Japanese Patent Laid-Open No. 53-113256.
[0003]
The above-mentioned Japanese Patent Laid-Open No. 51-8160 is a method for bending a refrigeration-type hollow double pipe for an automobile exhaust pipe or the like, in which liquid such as water is frozen in a hollow portion between the inner and outer pipes of a straight pipe hollow-type double pipe The two ends of the liquid injection are sealed to freeze the sealed liquid, and the double pipe is bent to the required angle by a press bender or other bending machine. And the sealing part of this pipe is cut and removed, and the freezing part in this pipe is dissolved by overheating and eliminated.
[0004]
Japanese Patent Laid-Open No. 53-113256 discloses a method of bending a double pipe in which a heat insulating material is sandwiched, and one end of the double pipe in which a heat insulating material is interposed between an inner and outer pipe is covered with an appropriate lid. Close the tube, fill the inside pipe with water, impregnate the insulation material with water, and store it in a freezing solution tank, etc. to freeze the water in the double pipe. It is bent and left to dissolve frozen water naturally.
[0005]
The above two exhaust system double pipes are bent in a state where the liquid put in the pipe is frozen, and in any case, the inner pipe has a solid wall structure in which no hole is made. For this reason, although the heat insulation effect which does not transmit the temperature of the high temperature exhaust gas which passes the inside of an inner pipe to an outer pipe is exhibited, there exists a problem that the silencing effect by a heat insulating material is not exhibited so much. The reason is that the high-pressure exhaust gas in the inner pipe passes through the pipe without being able to expand.
[0006]
Therefore, a number of small holes are made in the peripheral wall surface of the inner pipe, and a part of the high-pressure exhaust gas can expand to the heat insulating material through the small holes, so that the noise is reduced by reducing the pressure somewhat. An improved double pipe can be proposed. However, as shown in FIG. 9, when a small number of small holes 7 formed in the inner pipe 5 are bent by the above bending method, the small holes 7 on the outer side 9 </ b> A in the bent portion 9 are stretched to cause cracks. Or the inner side 9B of the bent portion 9 is compressed to the center and becomes a "wrinkle", resulting in a reduced cross-sectional shape.
[0007]
Then, a processing method is proposed in which the outer pipe is divided into two parts, bent by press working, a heat insulating material is interposed between the inner and outer pipes, and finally the joint portion of the outer pipe is welded. However, in the processing method in which the outer pipe is split in half and finally welded, the manufacturing process becomes complicated, and the equipment costs for the press device and welding device used for this increase, and the manufacturing cost of the exhaust double pipe There is a problem that the welding beat is exposed and the appearance is deteriorated.
[0008]
[Problems to be solved by the invention]
The present invention was made in view of the problem of the manufacturing method of the conventional exhaust system double pipe, and there is no crack or wrinkle in the bent part, and a smooth bent shape can be obtained, and the exhaust gas can be made smooth. It is an object of the present invention to provide an exhaust system double pipe manufacturing method and pipe capable of exhaust.
[0009]
[Means for Solving the Problems]
The present invention has been made to achieve the above object, and the method of manufacturing an exhaust system double pipe according to claim 1 is a straight tube in which a number of long holes are formed in a staggered manner in a direction orthogonal to the axial direction. The inner pipe is inserted into the straight outer pipe, and a process of joining the inner and outer pipes with a silencer interposed between the inner and outer pipes, and one end of the double pipe is closed with a lid, Filling the freezing liquid, cooling the entire double pipe to freeze the liquid in the double pipe, bending the double pipe to a desired angle by a bending means, and the double pipe And a step of removing the liquid from the inside.
[0010]
According to a second aspect of the present invention, there is provided a method of manufacturing an exhaust system double pipe, in which a straight tubular inner pipe having a plurality of small holes and having a bellows portion that can expand and contract in the axial direction is inserted into the straight tubular outer pipe. And a step of joining the inner and outer pipes with a silencer interposed between the inner and outer pipes, a step of closing one end of the double pipe with a lid, and filling the inside of the pipe with a freezeable liquid; Cooling the entire heavy pipe to freeze the liquid in the double pipe, bending the double pipe to a desired angle with a bending means, and removing the liquid from the double pipe. It is characterized by.
[0011]
The exhaust pipe double pipe manufacturing method according to claim 3 includes inserting a straight tubular inner pipe formed of an expanded material formed by drilling a large number of rhombus or turtle shell-shaped holes into the straight tubular outer pipe. A step of joining a double pipe structure in which a sound deadening material is interposed between the inner and outer pipes, a step of closing one end of the double pipe with a lid, and filling the pipe with a freezeable liquid, Cooling the entire double pipe to freeze the liquid in the double pipe, bending the double pipe to a desired angle with a bending means, and removing the liquid from the double pipe. It is characterized by becoming.
[0012]
5. The exhaust pipe according to claim 4, wherein the inner pipe is inserted inside the outer pipe, and a sound deadening material is interposed between the outer pipe and the inner pipe. A large number of long holes are formed in a staggered manner in a direction perpendicular to the axial direction on the peripheral surface of the surface, and a portion where the long holes are formed is bent at an appropriate angle.
[0013]
6. The exhaust system double pipe according to claim 5, wherein the inner pipe is inserted inside the outer pipe, and a sound deadening material is interposed between the outer pipe and the inner pipe. The peripheral surface is formed with a plurality of small holes and a bellows portion that can be expanded and contracted in the axial direction, and the bellows portion is bent at an appropriate angle.
[0014]
The exhaust pipe according to claim 6 is a double pipe in which an inner pipe is inserted inside an outer pipe, and a sound deadening material is interposed between the outer pipe and the inner pipe. The peripheral surface is formed of an expanded material in which a large number of rhombus or turtle shell-shaped holes are formed, and the expanded material portion is bent at an appropriate angle.
[0015]
[Action]
In the manufacturing method according to the first aspect of the present invention, first, an inner pipe in which a large number of elongated holes are formed in a zigzag shape in a direction perpendicular to the axial direction is inserted into the straight outer pipe. The inner and outer pipes are joined by welding or the like as a double pipe structure in which a silencer is interposed between the pipes. Then, one end of the double pipe is closed with a lid, and the pipe is filled with a liquid such as water that can be frozen. Further, the entire double pipe is cooled to freeze the liquid in the double pipe. Thereafter, it is bent at a desired angle by a bending means, and the liquid is discharged and removed from the double pipe to produce an exhaust system double pipe.
[0016]
According to the exhaust pipe double pipe manufacturing method, the double pipe has a long length in the direction orthogonal to the axial direction on the peripheral surface of the inner pipe with the silencer interposed between the inner and outer pipes. A large number of holes are formed in a staggered pattern. When the portion where the elongated hole is formed is bent, the elongated hole is easily expanded and deformed in the axial direction on the outer diameter side of the bending with respect to the bending force in the direction orthogonal to the axial direction. The side is easily reduced and deformed in the axial direction. Therefore, the portion in which the elongated hole is formed can freely expand and contract, and can be easily bent to a desired angle without causing cracks or wrinkles on the wall surface of the inner pipe.
[0017]
In the manufacturing method of claim 2, first, a large number of small holes are drilled, and a straight tubular inner pipe having a bellows portion that can expand and contract in the axial direction is inserted into the straight tubular outer pipe. The inner and outer pipes are joined by welding or the like as a double pipe structure in which a silencer is interposed between the pipes. Then, one end of the double pipe is closed with a lid, and the pipe is filled with a liquid such as water. Further, the entire double pipe is cooled to freeze the liquid in the double pipe. Thereafter, it is bent at a desired angle by a bending means, and the liquid is discharged and removed from the double pipe to produce an exhaust system double pipe.
[0018]
According to the above exhaust system double pipe manufacturing method, the double pipe has a number of small holes drilled on its peripheral surface with the sound deadening material interposed between the inner and outer pipes. At the same time, an accordion portion that can expand and contract in the axial direction is formed. When the portion where the bellows portion is formed is bent, the bellows portion is easily expanded and deformed in the axial direction on the outer diameter side of the bending with respect to the bending force in the direction orthogonal to the axial direction. The side is easily reduced and deformed in the axial direction. Therefore, the portion where the bellows portion is formed can freely expand and contract, and can be easily bent to a desired angle without causing cracks or wrinkles on the wall surface of the inner pipe.
[0019]
In the manufacturing method of claim 3, first, a straight tubular inner pipe formed of an expanding material formed by drilling a large number of rhombus or turtle shell shaped holes is inserted into the straight tubular outer pipe, and between the inner and outer pipes. As a double pipe structure in which a sound deadening material is interposed between the inner and outer pipes, they are joined together by welding or the like. Then, one end of the double pipe is closed with a lid, and the pipe is filled with a liquid such as water that can be frozen. Further, the entire double pipe is cooled to freeze the liquid in the double pipe. Thereafter, it is bent at a desired angle by a bending means, and the liquid is discharged and removed from the double pipe to produce an exhaust system double pipe.
[0020]
According to the above exhaust system double pipe manufacturing method, the double pipe is formed with a number of rhombus or turtle shell-shaped holes in a state in which a silencer is interposed between the inner and outer pipes. It is made of expanded material. When the portion formed of the expand material is bent, the rhomboid or turtle shell-shaped hole is easily expanded and deformed in the axial direction on the outer diameter side of the bending with respect to the bending force in the direction perpendicular to the axial direction. The inner diameter side of the bending is easily reduced and deformed in the axial direction. Therefore, the portion in which the rhombus or turtle shell-shaped hole is formed can freely expand and contract, and can be easily bent to a desired angle without causing cracks or wrinkles in the wall surface of the inner pipe.
[0021]
In the exhaust system double pipe according to claim 4, the elongated hole formed in the peripheral surface of the inner pipe freely expands and contracts at the bent portion, and the inner surface becomes a smooth surface without cracks and wrinkles, and the exhaust flow Can be smooth. Therefore, when the high-temperature and high-pressure exhaust gas from the engine passes through the inner pipe, the exhaust gas effectively expands from the many long holes to the silencer, lowering the internal pressure, and exhibiting an excellent silencing effect In addition, exhaust gas is exhausted efficiently.
[0022]
In the exhaust system double pipe according to claim 5, the bellows part formed on the peripheral surface of the inner pipe freely expands and contracts at the bent portion, and the inner surface becomes a smooth surface without cracks and wrinkles, and the exhaust gas flow. Can be smooth. Therefore, when the high-temperature and high-pressure exhaust gas from the engine passes through the inner pipe, the exhaust gas effectively expands from the many long holes to the silencer, lowering the internal pressure, and exhibiting an excellent silencing effect In addition, exhaust gas is exhausted efficiently.
[0023]
In the exhaust system double pipe according to claim 6, at the bent portion, the rhombus or turtle shell-shaped hole formed in the peripheral surface of the inner pipe freely expands and contracts to become a smooth surface without cracks or wrinkles on the inner surface. , The flow of exhaust can be made smooth. Therefore, when the high-temperature and high-pressure exhaust gas from the engine passes through the inner pipe, the exhaust gas effectively expands from the many long holes to the silencer, lowering the internal pressure, and exhibiting an excellent silencing effect In addition, exhaust gas is exhausted efficiently.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 is an external view of a silencer attached to an engine such as a motorcycle, FIG. 2 is a cross-sectional view of an exhaust system double pipe according to the present invention, FIG. 3 is a process diagram of the manufacturing method, and FIG. It is sectional drawing explaining the exhaustion effect | action of a pipe.
[0025]
FIG. 1 shows a silencer 1 attached to an engine such as a motorcycle, an exhaust pipe 2 connected to an exhaust port of the engine, a joint pipe which is an exhaust system double pipe 100 provided subsequently thereto, The silencer main body 3 follows. As shown in FIG. 2, in the exhaust system double pipe 100 according to the present invention, the inner pipe 20 </ b> A is inserted inside the outer pipe 10. A silencer K made of stainless wool or steel wool having high heat resistance is interposed between the peripheral surface 11 of the outer pipe 10 and the peripheral surface 23A of the inner pipe 20A. In addition, a large number of elongated holes 15 are formed in a staggered manner in the whole circumferential surface 23A of the inner pipe 20A or a part to be bent, in a direction perpendicular to the axial direction O.
[0026]
When the exhaust pipe 100 is bent, the long hole 15 of the inner pipe 20A is easily deformed in the axial direction on the outer diameter side of the bending with respect to the bending force Fo in the direction orthogonal to the axial direction O. Thus, the inner diameter side of the bending is easily reduced and deformed in the axial direction. Therefore, the inner pipe 20A is appropriately bent at an angle Q without causing cracks or wrinkles.
[0027]
Next, a manufacturing process of the exhaust system double pipe 100 will be described with reference to FIG. In advance, a large number of long holes 15 are formed in a zigzag shape in the direction orthogonal to the axial direction O on the entire peripheral surface of the inner pipe 20A or a part to be bent. The portion that is not bent may be a normal round small hole. Next, a silencer K made of stainless wool or steel wool having high heat resistance is wound around the peripheral surface of the inner pipe 20 </ b> A, and the inner pipe 20 </ b> A is inserted into the straight tubular outer pipe 10. And the appropriate place (for example, edge part) of this inner pipe 20A and the outer pipe 10 is joined and integrated by welding etc. (assembly process A).
[0028]
Next, one end 30X of the double pipe 30A is closed with a lid 35, and the pipe is filled with a liquid W such as water that can be frozen (filling step B). As the frozen liquid W, water, ice, liquid paraffin, or the like can be used. Next, the entire double pipe 30A is cooled by the refrigerator L to freeze the liquid W in the double pipe (freezing step C). Thereafter, the double pipe is bent to a desired angle by a bending means (pipe bender, press machine, etc.) M (bending step D). Next, the entire pipe is heated and dried with a dryer H, and the liquid is removed from the double pipe 30A (liquid exclusion step E).
[0029]
In the method of manufacturing the exhaust system double pipe 100, the double pipe 30A has a silencer K interposed between the inner and outer pipes 10 and 20A, and the inner pipe 20A is orthogonal to the axial direction O on the peripheral surface thereof. A large number of long holes 15 extending in the direction are formed in a staggered manner. When this is frozen and then bent to a desired angle by a bending means (pipe bender, press machine, etc.) M, the inner pipe 20A has the long hole 15 perpendicular to the axial direction O as shown in FIG. The bending outer diameter side easily expands and deforms in the axial direction O while the bending inner diameter side easily contracts and deforms in the axial direction O. Therefore, the inner pipe 20A can be easily bent to a desired angle Q without generating cracks or wrinkles on the wall surface.
[0030]
In the method of manufacturing the exhaust system double pipe 100, in the assembly step A, as shown in FIG. 3, the inner pipe 20A is inserted into the straight outer pipe 10, and then the inner and outer pipes 10 are inserted. 20A may be inserted into the double pipe 30A and joined by welding or the like.
[0031]
The exhaust system double pipe 100 manufactured as described above is such that when the high-temperature and high-pressure exhaust gas G from the engine passes through the inner pipe 20A of the double pipe 30A, the inner surface of the inner pipe 20A is cracked or wrinkled. Since there is no smooth surface, the exhaust circulation is smooth. Therefore, the high-temperature and high-pressure exhaust gas from the engine is effectively expanded from the long holes 15 to the silencer K to reduce the internal pressure, exhibit an excellent silencing effect, and exhaust the exhaust gas efficiently. .
[0032]
Next, the exhaust system double pipe 200 according to the second embodiment will be described with reference to FIGS. In the exhaust system double pipe 200, the inner pipe 20 </ b> B is inserted inside the outer pipe 10. A silencer K made of stainless wool or steel wool having high heat resistance is interposed between the peripheral surface 11 of the outer pipe 10 and the peripheral surface 23B of the inner pipe 20B. The inner pipe 20B has a large number of small holes 17 formed in the peripheral surface 23B, and the entire peripheral surface 23A or a part to be bent is a bellows that can be expanded and contracted in the axial direction O. The part is formed.
[0033]
When the exhaust pipe 200 is bent, the bellows portion of the inner pipe 20B can be easily deformed by expanding the outer diameter side of the bend in the axial direction with respect to the bending force Fo in the direction perpendicular to the axial direction O. The inner diameter side of the bending is easily reduced and deformed in the axial direction. Accordingly, the exhaust system double pipe 200 is appropriately bent at an angle Q without causing cracks or wrinkles in the inner pipe 20B.
[0034]
The exhaust system double pipe 200 is manufactured by the manufacturing process shown in FIG. A large number of small holes 17 are formed in the peripheral surface 23B of the inner pipe 20B in advance, and a bellows portion that can be expanded and contracted in the axial direction O is formed in all or a part to be bent. The portion that is not bent may be a normal perforated tube. Next, the sound deadening material K made of stainless wool or steel wool having high heat resistance is wound around the outer peripheral surface of the inner pipe 20B, and the inner pipe 20A is inserted into the straight tubular outer pipe 10. And the appropriate place (for example, edge part) of this inner pipe 20B and the outer pipe 10 is joined and integrated by welding etc. (assembly process A).
[0035]
Next, one end 30X of the double pipe 30B is closed with a lid 35, and the pipe is filled with a liquid W such as water that can be frozen (filling step B). Next, the entire double pipe 30B is cooled by the refrigerator L to freeze the liquid W in the double pipe (freezing step C). Thereafter, it is bent at a desired angle by a bending means (pipe bender, press machine, etc.) M (bending step D). Next, the entire pipe is heated and dried with a dryer H to exclude liquid from the double pipe (liquid exclusion step E).
[0036]
In the manufacturing method of the exhaust system double pipe 200, the double pipe 30B has a silencer K interposed between the inner and outer pipes 10 and 20B, and the inner pipe 20B has a large number of small holes 17 on the peripheral surface 23B. A bellows portion that is drilled and expandable in the axial direction O is formed. When this is frozen and then bent to a desired angle by a bending means (pipe bender, press machine, etc.) M, the bellows portion of the inner pipe 20B is in a direction perpendicular to the axial direction O as shown in FIG. With respect to the bending force Fo, the outer diameter side of the bending is easily expanded and deformed in the axial direction, and the inner diameter side of the bending is easily reduced and deformed in the axial direction. Therefore, the inner pipe 20B can be easily bent to a desired angle Q without generating cracks or wrinkles on the wall surface.
[0037]
In the method of manufacturing the exhaust system double pipe 200, as shown in FIG. 6, in the assembly process A, the inner pipe 20B is inserted into the straight outer pipe 10, and then the inner and outer pipes 10 are inserted. 20B may be inserted into the double pipe 30B and joined by welding or the like.
[0038]
The exhaust system double pipe 200 manufactured as described above is such that when the high-temperature and high-pressure exhaust gas G from the engine passes through the inner pipe 20B of the double pipe 30B, the inner surface of the inner pipe 20B is cracked or wrinkled. Since there is no smooth surface, the exhaust circulation is smooth. Therefore, the high-temperature and high-pressure exhaust gas from the engine effectively expands from the large number of small holes 17 to the silencer K to lower the internal pressure, exhibit an excellent silencing effect, and exhaust the exhaust gas efficiently. .
[0039]
Subsequently, an exhaust system double pipe 300 according to a third embodiment will be described with reference to FIGS. In the exhaust system double pipe 300, the inner pipe 20 </ b> C is inserted inside the outer pipe 10. A silencer K made of stainless wool or steel wool having high heat resistance is interposed between the peripheral surface 11 of the outer pipe 10 and the peripheral surface 23C of the inner pipe 20C. The inner pipe 20C is formed of an expanded material having a large number of rhombus or turtle shell-shaped holes formed in the peripheral surface 23C. This is a mesh-like member in which a large number of slits are formed in a staggered pattern in a steel plate and stretched by a stretcher to form a large number of rhombus or turtle shell-shaped holes 19A. Is formed.
[0040]
When the exhaust pipe 300 is bent, the inner pipe 20C of the inner pipe 20C has a rhombus or a turtle shell shape with respect to a bending force Fo in a direction orthogonal to the axial direction O as shown in FIG. The hole 19A is easily enlarged and deformed in the axial direction O on the outer diameter side of the bending, and is easily reduced and deformed in the axial direction O on the inner diameter side of the bending. Accordingly, the exhaust system double pipe 300 is appropriately bent at an angle Q without causing cracks or wrinkles in the inner pipe 20C.
[0041]
The exhaust system double pipe 300 is manufactured by the manufacturing process shown in FIG. First, the inner pipe 20C is formed of an expanded material in which a large number of rhombus or turtle shell-shaped holes 19A are drilled, either entirely or partially. A silencer K made of stainless wool or steel wool with high heat resistance is wound around the outer peripheral surface of the inner pipe 20C, and the inner pipe 20C is inserted into the straight tubular outer pipe 10. And the appropriate place (for example, edge part) of this inner pipe 20C and the outer pipe 10 is joined and integrated by welding etc. (assembly process A).
[0042]
Next, one end 30X of the double pipe 30C is closed with a lid 35, and the pipe is filled with a liquid W such as water that can be frozen (filling step B). Next, the entire double pipe 30C is cooled by the refrigerator L to freeze the liquid W in the double pipe (freezing step C). Thereafter, it is bent at a desired angle by a bending means (pipe bender, press machine, etc.) M (bending step D). Next, the entire pipe is heated and dried with a dryer H to exclude liquid from the double pipe (liquid exclusion step E).
[0043]
In the method of manufacturing the exhaust system double pipe 300, the double pipe 30C has a silencer K interposed between the inner and outer pipes 10 and 20C, and the inner pipe 20C has a number of rhombus or turtle shell-shaped holes 19A. It is made of an expanded material. When this is frozen and then bent at a desired angle by a bending means (pipe bender, press machine, etc.) M, the diamond-shaped or turtle shell-shaped hole 19A is orthogonal to the axial direction O as shown in FIG. With respect to the bending force Fo in the direction, the outer diameter side of the bending is easily expanded and deformed in the axial direction O, and the inner diameter side of the bending is easily reduced and deformed in the axial direction O. Therefore, the inner pipe 20C can be easily bent to a desired angle Q without generating cracks or wrinkles on the wall surface.
[0044]
In the method of manufacturing the exhaust system double pipe 300, as shown in FIG. 6, in the assembly process A, the inner pipe 20C is inserted into the straight outer pipe 10 and then the inner and outer pipes 10 are inserted. 20C may be inserted into the double pipe 30B and joined by welding or the like.
[0045]
In the exhaust system double pipe 300 manufactured as described above, when the high-temperature and high-pressure exhaust gas G from the engine passes through the inner pipe 20C of the double pipe 30C, the inner surface of the inner pipe 20C is cracked or wrinkled. Since the surface is smooth, there is a smooth flow of exhaust. Therefore, the high-temperature and high-pressure exhaust gas from the engine effectively expands from the large number of diamond-shaped or turtle shell-shaped holes 19A to the sound deadening material K to lower the internal pressure, exhibit an excellent noise reduction effect, Exhaust efficiently.
[0046]
In addition, this invention is not limited to said each embodiment, The design change within a summary is possible. For example, the exhaust system double pipe is not limited to the joint pipe, and may be another pipe used in the exhaust system. Also, appropriate bending means can be employed for bending the inner and outer pipes. Moreover, instead of the method of thawing the frozen liquid and excluding it from the inside of the double pipe by heating and drying the entire double pipe with the dryer H, it may be naturally thawed.
[0047]
【The invention's effect】
According to the exhaust system double pipe manufacturing method of the first aspect of the present invention, since the portion where the elongated hole is formed freely expands and contracts, any cracks and wrinkles are not generated on the wall surface of the inner pipe. Can be easily bent in direction and angle.
[0048]
According to the exhaust pipe double pipe manufacturing method of claim 2, the bellows part that can be expanded and contracted in the axial direction freely expands and contracts, so that any direction can be obtained without causing cracks and wrinkles on the wall surface of the inner pipe. Can be easily bent to an angle.
[0049]
According to the exhaust pipe double pipe manufacturing method of claim 3, since the expanded material formed by drilling a large number of rhombus or turtle shell-shaped holes freely expands and contracts, it causes cracks and wrinkles on the wall surface of the inner pipe. And can be bent easily in any direction and angle.
[0050]
According to the exhaust system double pipe of claim 4, the elongated hole formed in the peripheral surface of the inner pipe freely expands and contracts at the bent portion, and a smooth surface without cracks and wrinkles is formed on the inner surface. Therefore, the distribution of the exhaust gas can be performed smoothly, exhibiting an excellent silencing effect, and exhaust gas can be efficiently exhausted.
[0051]
According to the exhaust system double pipe of claim 5, the bellows portion formed on the peripheral surface of the inner pipe freely expands and contracts at the bent portion, and a smooth surface without cracks and wrinkles is formed on the inner surface. Therefore, the distribution of the exhaust gas can be performed smoothly, exhibiting an excellent silencing effect, and exhaust gas can be efficiently exhausted.
[0052]
According to the exhaust system double pipe of claim 6, the rhombus or turtle shell-shaped hole formed in the peripheral surface of the inner pipe freely expands and contracts, and a smooth surface without cracks or wrinkles is formed on the inner surface. In addition, the flow of exhaust can be made smooth, exhibiting an excellent silencing effect, and exhaust gas can be exhausted efficiently.
[Brief description of the drawings]
FIG. 1 is an external view of an exhaust device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of an exhaust system double pipe according to the first embodiment of the present invention.
FIG. 3 is a manufacturing process diagram of an exhaust system double pipe according to the first embodiment of the present invention.
FIG. 4 is an enlarged sectional view of an exhaust system double pipe according to the first embodiment of the present invention.
FIG. 5 is a sectional view of an exhaust system double pipe according to a second embodiment of the present invention.
FIG. 6 is a manufacturing process diagram of an exhaust double pipe according to a second embodiment of the present invention.
FIG. 7 is a cross-sectional view of an exhaust system double pipe according to a third embodiment of the present invention.
FIG. 8 is a manufacturing process diagram of an exhaust system double pipe according to a third embodiment of the present invention.
FIG. 9 is a cross-sectional view of an exhaust system double pipe using an inner pipe with a round small hole.
[Explanation of symbols]
1 Silencer
10 Outer pipe
11 circumference
15 Long hole
17 Small hole
19A Diamond or Tortoise-shaped hole
20A Inner pipe
20B inner pipe
20C inner pipe
23A circumference
23B circumference
23C circumference
30A double pipe
30B Double pipe
30C double pipe
30X one end
35 lid
A assembly process
B Filling process
C Freezing process
D Bending process
E Liquid exclusion process
K silencer
L refrigerator
H dryer
M bending means
O Axial direction
W liquid
100, 200, 300 Double exhaust pipe

Claims (6)

Insert a straight tubular inner pipe with a large number of long holes in a staggered pattern in a direction perpendicular to the axial direction into the straight tubular outer pipe, and insert a silencer between the inner and outer pipes to connect the inner and outer pipes. A step of joining, a step of closing one end of the double pipe with a lid, a step of filling the pipe with a freezeable liquid, and a step of cooling the entire double pipe to freeze the liquid in the double pipe And a method of bending the double pipe to a desired angle by a bending means, and a step of removing liquid from the double pipe. A straight tubular inner pipe with a large number of small holes and a bellows part that can expand and contract in the axial direction is inserted into the straight tubular outer pipe, and a silencer is interposed between the inner and outer pipes. The process of joining the pipe, the process of closing one end of the double pipe with a lid and filling the pipe with a freezeable liquid, and cooling the entire double pipe to freeze the liquid in the double pipe And a step of bending the double pipe to a desired angle by a bending means, and a step of removing liquid from the double pipe. A straight tubular inner pipe formed of an expanded material formed with a large number of rhombus or turtle shell-shaped holes is inserted into the straight tubular outer pipe, and a silencer is interposed between the inner and outer pipes. A step of joining the double pipe structure, a step of closing one end of the double pipe with a lid, and filling the pipe with a freezeable liquid; and cooling the entire double pipe to liquid in the double pipe A method for producing an exhaust system double pipe, comprising: a step of freezing the pipe; a step of bending the double pipe to a desired angle by a bending means; and a step of removing liquid from the double pipe. An inner pipe is inserted inside the outer pipe, and a silencer is interposed between the outer pipe and the inner pipe, and the circumferential surface of the inner pipe is perpendicular to the axial direction. The exhaust system double pipe is characterized in that a large number of long long holes are formed in a zigzag shape, and a portion where the long holes are formed is bent at an appropriate angle. An inner pipe is inserted inside the outer pipe, and a silencer is interposed between the outer pipe and the inner pipe, and the peripheral surface of the inner pipe has many small holes. An exhaust bellows part that can be expanded and contracted in the axial direction is formed, and the bellows part is bent at an appropriate angle. An inner pipe is inserted inside the outer pipe, and a sound deadening material is interposed between the outer pipe and the inner pipe. The inner pipe has a large number of rhombus or turtle shell-shaped holes. An exhaust system double pipe, wherein the expanded material part is formed by an expanded material formed by drilling and having the expanded material part bent at an appropriate angle.

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