JP2005041267A - Fuel pipe and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pipe 30 which is used for a fuel feeding device 10 is equipped with a ventilation way 45 for a breather, can ensure a stable fuel feeding amount, and at the same time, of which the assembling work is easy, and of which the manufacture is simple as well. <P>SOLUTION: The fuel feeding device 10 is equipped with a filler neck 20 and the fuel pipe 30. The fuel pipe 30 is bent along a fuel feeding path, is connected with a fuel tank FT, and is equipped with an external pipe 31 and an internal pipe 40 which is arranged in the external pipe 31. The internal pipe 40 becomes a tube passage 40P which constitutes a part of a fuel feeding passage 10P, and a gap between the external pipe 31 and the internal pipe 40 becomes the ventilation passage 45 which performs a breather action. The internal wall of the internal pipe 40 is welded to valley-shape parts 35a and 36a of the bellows sections 35 and 36 of the external pipe 31, and a space between them is formed into a connection passage 46. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel conduit having a fuel supply passage through which fuel flows and an air passage, and a method for manufacturing the fuel conduit.
[0002]
[Prior art and problems]
Conventionally, what is applied to the fuel filler pipe of a motor vehicle is known as a fuel conduit. The fuel filler pipe includes a pipe body that allows fuel from the fuel gun to flow, and a breather pipe branched from the pipe body. The breather pipe is formed from a pipe separate from the pipe body. However, as a configuration for facilitating the routing, a technique of incorporating a breather pipe in the pipe body is known (for example, Patent Document 1).
[0003]
However, in the conventional technique, the flow resistance of the fuel increases due to the position of the inner pipe, and it is difficult to secure a stable fuel supply amount. Further, when the bellows portion for facilitating the bending of the pipe body is formed, it is difficult to secure a predetermined fuel injection amount due to the flow resistance of the bellows portion. Furthermore, a means for fixing the breather pipe in the pipe body is necessary, and the assembling work is troublesome.
[0004]
As another conventional technique, a metal filler pipe having a double pipe structure has also been proposed (for example, Patent Document 2). In this technique, it is necessary to insert a metal breather pipe into a metal pipe body and fix them at both ends. Further, when the metal filler pipe has a bent shape, it is necessary to bend the breather pipe into a predetermined shape in advance, and the insertion workability is not good.
[Patent Document 1]
Japanese Utility Model Publication No. 62-83724 [Patent Document 2]
Japanese Utility Model Publication No. 61-200726 [0006]
An object of the present invention is to solve the above-described problems of the prior art, and to provide a fuel conduit that can secure a stable fuel supply amount and that can be easily assembled and a method for manufacturing the same.
[0007]
[Means for solving the problems and their functions and effects]
The present invention made to solve the above problems
A fuel conduit comprising an outer pipe and an inner pipe disposed in the outer pipe with a gap serving as a ventilation path,
The outer pipe has a bellows part at least in a part thereof,
The inner pipe has a cylindrical outer peripheral surface joined to the inner wall of the valley portion of the bellows portion, and a connection path communicating with the air passage between the bellows portion and the outer peripheral surface of the inner pipe. Forming.
[0008]
According to the fuel conduit of the present invention, the inner pipe is integrally formed in the outer pipe having the bellows portion, and at the same time, the air passage and the connection path can be secured between the outer pipe and the inner pipe. The number of parts can be reduced and assembly work is unnecessary.
[0009]
Moreover, since the inner pipe is welded to the valley portion of the bellows portion of the outer pipe, it does not buckle during bending and does not narrow or block the passage area of the inner pipe.
[0010]
Further, the air passage and the connection passage as the breather passage are arranged outside the inner pipe and do not hinder the fuel flow, so that a stable fuel supply amount can be ensured.
[0011]
As a preferable aspect of the connection path, it can be configured by forming the bellows portion in a spiral shape. In addition, the other connection path may be formed of a short-circuit path in which the bellows portions are formed in a large number of annular paths arranged in the axial direction, and the annular paths are short-circuited to be connected.
[0012]
Another aspect of the invention is a method of manufacturing a fuel conduit,
Extruding the first extruded tube for forming the outer pipe and extruding the second extruded tube for forming the inner pipe into the first extruded tube; and
The bellows portion is formed on the first extruded tube body by the molding surface of the mold while conveying the molds arranged on both sides of the extruded first extruded tube body, and the second A shaping step of blowing a compressed gas into the extruded tube body to bring the outer wall of the second extruded tube body into close contact with the inner wall of the valley portion of the bellows portion, and forming the air passage therebetween,
It is provided with.
[0013]
According to the manufacturing method of the present invention, the fuel pipe has high productivity because the outer pipe and the inner pipe can be continuously manufactured by extrusion molding.
[0014]
After the shaping step, a step of bending the fuel conduit to a predetermined shape by heating it along the recess of the mold can be performed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(1) Schematic Configuration of Fuel Refueling Device 10 FIG. 1 is a schematic diagram showing a fueling device according to this embodiment. As shown in FIG. 1, the fuel refueling device 10 is disposed between the inlet box IB and the fuel tank FT, and sends fuel supplied from a fuel gun (not shown) to the fuel tank FT. A filler neck 20 having an inlet 21a that is opened and closed by a cap CP, and a fuel conduit 30 that connects the filler neck 20 and the pipe connector 50 of the fuel tank FT are provided. That is, the vehicle body panel VP of the automobile is provided with an inlet box IB, and a filler neck 20 is attached to the bottom of the inlet box IB. The fuel conduit 30 is bent along the fuel supply path and connected to the fuel tank FT. The fuel conduit 30 includes an outer pipe 31 and an inner pipe 40 disposed in the outer pipe 31, and the inside of the inner pipe 40 supplies fuel. A tube passage 40P that constitutes a part of the passage 10P is formed, and a gap between the outer pipe 31 and the inner pipe 40 is a ventilation passage 45 that performs a breather function. At the time of refueling, when the fuel cap CP is removed and fuel is injected from the fuel gun into the filler neck 20, the fuel is supplied into the fuel tank FT through the fuel supply passage 10P. Hereinafter, the configuration of each unit will be described in detail.
[0016]
(2) Configuration of each part (2) -1 Filler neck 20
FIG. 2 is an enlarged cross-sectional view of a part of the filler neck 20 and the fuel conduit 30 of the fuel supply apparatus 10 shown in FIG. In FIG. 2, a filler neck 20 includes a neck body 21 that connects an injection port 21a and an outflow port 21b and constitutes an injection passage 20P that is a part of the fuel supply passage 10P. At the lower end of the neck body 21, a neck connection portion 22 having an outlet 21b for connecting the fuel conduit 30 is formed. On the outer periphery of the neck connection portion 22, an annular protrusion 22 a that extends and prevents the pipe connection end 31 d of the outer pipe 31 constituting the fuel conduit 30 is formed. A fitting 24 for attaching the fuel cap CP so as to be freely opened and closed is attached to the inside of the neck body 21. A seal member 25 made of an O-ring is interposed between the mounting bracket 24 and the inner wall of the neck body 21.
[0017]
(2) -2 Fuel conduit 30
In FIG. 1, the fuel conduit 30 includes an outer pipe 31, an inner pipe 40 disposed in the outer pipe 31 with a gap serving as a ventilation path 45, and an introduction portion 43 attached to the tip of the inner pipe 40. It has. The outer pipe 31 includes straight pipe portions 32, 33, 34 and bellows portions 35, 36 that are bent along an oil supply path formed between the straight pipe portions 32, 33, 34. The bellows portions 35 and 36 are formed in a spiral shape. The outer pipe 31 has a pipe connection end 31d connected to the neck connection portion 22 of the filler neck 20 at one end and a pipe connection end 31e connected to the pipe connection body 50 of the fuel tank FT at the other end. I have.
[0018]
The inner pipe 40 has a cylindrical shape, forms a tube passage 40P that constitutes a part of the fuel supply passage 10P, and is disposed over the entire length of the outer pipe 31. FIG. 3 is an enlarged cross-sectional view of the main part of the fuel conduit 30. The outer peripheral surface of the inner pipe 40 is thermally welded to the inner walls of the valley portions 35 a and 36 a of the bellows portions 35 and 36 of the outer pipe 31. Since the bellows portions 35 and 36 have a spiral shape as described above, a connection path 46 constituting a part of the ventilation path 45 is formed between the bellows sections 35 and 36 and the outer peripheral surface of the inner pipe 40. The ventilation path 45 and the connection path 46 are connected to the injection port 21a of the filler neck 20 shown in FIG. 1 and serve as a breather path for releasing the internal pressure of the fuel tank FT when fuel is injected.
[0019]
FIG. 4 is an enlarged cross-sectional view of the outer pipe 31 and the inner pipe 40. The outer pipe 31 is formed of three layers in which an inner layer 31a, a barrier layer 31b, and an outer layer 31c are stacked. The inner layer 31a and the outer layer 31c are made of a polyethylene (modified PE) resin material modified with maleic acid (polar functional group). The barrier layer 31b is made of an ethylene vinyl alcohol copolymer (EVOH) having excellent fuel permeation resistance. Since the modified PE has a property of being thermally welded to EVOH because it is modified with maleic acid, the barrier layer 31b is thermally welded to the inner layer 31a and the outer layer 31c. The inner pipe 40 is formed in a single layer from polyethylene (PE). Since the PE of the inner pipe 40 is compatible with the inner layer 31a of the outer pipe 31, they are thermally welded to each other. That is, the inner layer 31a functions as an adhesive layer that bonds the inner pipe 40 and the outer pipe 31 together. Further, the outer pipe 31 contains 0.1 to 2.0 parts by weight of carbon black for laser welding described later.
[0020]
In FIG. 2, an introduction portion 43 is joined to the upper portion of the inner pipe 40. The introduction portion 43 is disposed in the filler neck 20 and has a funnel shape with an opening area increased toward the injection port 21a.
[0021]
(2) -3 Connection Structure of Fuel Conduit 30 and Pipe Connection Body 50 FIG. 5 is an enlarged sectional view of the vicinity of the pipe connection body 50 of the fuel tank FT. The fuel tank FT is formed of a plurality of resin layers in which polyethylene is disposed as an outer layer. A tank opening FTa is formed on the outer wall of the fuel tank FT, and a pipe connector 50 is welded so as to surround the tank opening FTa. ing. The pipe connector 50 includes a pipe main body 51 and a pipe support portion 55 integrated with the pipe main body 51 and two-color molding.
The tube body 51 is integrally formed with a cylindrical portion 52 that forms a passage 52 a and a flange portion 53 that is formed on the outer periphery of one end of the cylindrical portion 52. An annular protrusion 52b having a triangular cross section for welding is formed on the outer peripheral end of the cylindrical portion 52, and a weld portion 53a welded to the fuel tank FT is formed in the flange portion 53 in an annular shape.
The tube support portion 55 includes a cylindrical support portion 56, a flange portion 57, and a discharge portion 58, which are integrally formed. A portion of the outer surface of the cylindrical support portion 56 is welded to the pipe body 51 from the upper surface of the flange portion 57. On the outer surface of the cylindrical support portion 56, three rows of annular projections 56a having a triangular cross section for preventing the outer pipe 31 from protruding are provided.
One end of the discharge portion 58 is an open end 58a cut in the horizontal direction, and the open end 58a coincides with the full liquid level FL1 of the fuel tank FT. An inner pipe 40 extends from the opening end 58a of the discharge portion 58 to the inside of the fuel tank FT, and a space between the discharge portion 58 and the inner pipe 40 forms a part of the air passage 45. With this configuration, when the fuel level FL of the fuel tank FT is lower than the full tank level FL1, the fuel vapor is released from the air passage 45 formed by the space between the discharge part 58 and the inner pipe 40. When the fuel liquid level FL reaches the full tank liquid level FL1, the air passage 45 is blocked to increase the internal pressure of the fuel tank FT, thereby operating the auto-stop of the fuel gun.
[0022]
The pipe body 51 is made of modified PE, which is the same resin material as the inner layer 31a (see FIG. 4) of the outer pipe 31. On the other hand, the tube support portion 55 is made of polyamide (PA) having high mechanical strength. The polyamide is reactively bonded to the modified PE to which a polar functional group is added by maleic acid modification. By such a resin combination of the tube main body 51 and the tube support portion 55, the tube connection body 50 is integrated by two-color molding. The outer pipe 31 of the fuel conduit 30 is press-fitted into the outer periphery of the pipe connector 50.
[0023]
(3) Manufacturing method of fuel conduit 30 (3) -1 Manufacturing device 60
Next, the manufacturing process of the fuel conduit 30 will be described. FIG. 6 is an explanatory view for explaining an apparatus for manufacturing the fuel conduit 30. The manufacturing apparatus 60 includes an extrusion device 62, a molding die unit 70, a transport device 80, and a suction device (not shown).
[0024]
FIG. 7 is a schematic configuration diagram illustrating the extrusion device 62 and the mold 71. The extrusion device 62 is composed of a first extrusion tube body 31A for forming the outer pipe 31, a die 63 for extruding the second extrusion tube body 40A for forming the inner pipe 40, a screw and a cylinder 3 Resin supply for supplying resin to be a single-layer second extruded tube body 40A, which is composed of a resin supply mechanism 64a, 64c, 64d for supplying the resin to be the first extruded tube body 31A of the layer, and a screw and a cylinder. Between the mechanism 64b, a compressed gas supply source 65a for supplying compressed gas into the second extruded tube body 40A through the passage in the die 63, and between the first extruded tube body 31A and the second extruded tube body 40A. A compressed gas supply source 65b that supplies the compressed gas, and a controller 66 that controls the resin supply mechanisms 64a, 64b, 64c, and 64d and the compressed gas supply sources 65a and 65b are provided. The extrusion device 62 extrudes the modified PE, EVOH, and modified PE supplied from the resin supply mechanisms 64a, 64c, and 64d from the three paths of the die 63 to form the outer pipe 31 in three layers, and In order to form a single layer, the modified PE supplied from the resin supply mechanism 64b is pushed out from one path. In this configuration, after forming the bellows portion on the first extruded tube body 31A, the central portion of the die 63 is a projecting portion 63a projecting out the second extruded tube body 40A.
[0025]
The molding die unit 70 includes a plurality of molds 71 (71A, 71B...) Each having a molding surface following the respective parts of the outer pipe 31 and the inner pipe 40, and these are the first and second extrusions. It arrange | positions so that the pipe bodies 31A and 40A may each pass along the conveyance path | route in which it is conveyed. The mold 71 is composed of split molds divided along the central axes of the first and second extruded tubular bodies 31A and 40A to be conveyed, and each of these split molds is a loop shape, and the mold clamping is performed Are arranged to be. A suction passage connected to a suction pump (not shown) is opened on the molding surface of the mold 71. That is, the mold 71A has a bellows molding surface 71a for shaping the bellows portions 35, 36 on the outer shape of the first extruded tube 31A, and the mold 71B shapes the straight pipe portions 32, 33, 34. It has a straight pipe forming surface 71b.
[0026]
(3) -2 Each process Next, the process which manufactures the fuel conduit | pipe 30 using the said manufacturing apparatus 60 is demonstrated. The first and second extruded tube bodies 31A and 40A are respectively extruded while being blown through the passage by the compressed gas supply source 65a of the extrusion device 62. At the same time, the conveying device 80 molds the first and second extruded tube bodies 31A and 40A by clamping the mold 71 (71A, 71B...) While conveying the mold 71 (71A, 71B...) In a loop shape. A fuel conduit 30 constituting the outer pipe 31 and the inner pipe 40 is formed.
[0027]
Here, after shaping the bellows portion by causing the first extruded tube body 31A to follow the bellows molding surface 71a of the mold 71A, the second extruded tube body 40A is extruded from the protruding portion 63a of the die 63. By blowing compressed gas into the second extruded tube body 40A, the outer wall surface of the second extruded tube body 40A is pressed against the bellows-shaped valley portion of the first extruded tube body 31A. The first and second extruded tube bodies 31A and 40A are in a softened state immediately after extrusion, and the resin constituting the inner layer 31a of the first extruded tube body 31A and the second extruded tube body 40A is the same material. Therefore, the bellows-shaped valley portion is welded to the outer wall surface of the second extruded tubular body 40A (see FIG. 4).
In addition, the first extruded tube body 31A is made to follow the straight tube forming surface 71b of the mold 71B, and a compressed gas is blown between the first extruded tube body 31A and the second extruded tube body 40A. Then, while forming a straight pipe portion in a part of the first extruded tube body 31A, it is shaped so as to form a predetermined gap between the second extruded tube body 40A and a part of the air passage 45.
[0028]
Next, the fuel conduit 30 is obtained by repeating the reverse steps described above and cutting the shaped first and second extruded tube bodies 31A, 40A at predetermined positions. Further, the fuel conduit 30 is preheated and bent along the bending recess of the mold. At this time, the inner pipe 40 is bent while maintaining the welded state to the inner walls of the valley portions 35a and 36a of the bellows portions 35 and 36 of the outer pipe 31.
[0029]
(4) Assembly Step of Fuel Conduit 30 (4) -1 As shown in FIG. 1, the fuel conduit 30 is constructed by assembling the introduction part 43 on the upper part of the outer pipe 31, and further, the filler neck 20 and the mounting bracket 24, seal member 25 and the like are attached. And the fuel supply apparatus 10 is assembled | attached to the fuel tank FT by press-fitting the pipe connection end 31e of the outer side pipe 31 to the pipe connection body 50 in the assembly line of a motor vehicle.
[0030]
(5) Actions and effects of the embodiment The configuration of the above embodiment provides the following effects in addition to the above-described effects.
[0031]
(5) -1 According to the fuel conduit 30, the inner pipe 40 is simultaneously formed in the outer pipe 31 having the bellows portions 35 and 36, and the air passage 45 and the connection path are provided between the outer pipe 31 and the inner pipe 40. Since 46 can be secured, a breather pipe or the like is not required separately, the number of parts can be reduced, and assembly work is unnecessary.
[0032]
(5) -2 Since the fuel conduit 30 can continuously manufacture the outer pipe 31 and the inner pipe 40 by extrusion molding, the productivity is high.
[0033]
(5) -3 Since the inner pipe 40 is welded to the valley portions 35a and 36a of the bellows portions 35 and 36 of the outer pipe 31, the inner pipe 40 is folded during bending to narrow the passage area of the tube passage 40P. There is no blockage.
[0034]
(5) -4 The air passage 45 and the connection passage 46 as the breather passage are disposed outside the inner pipe 40 of the fuel supply passage 10P, and do not hinder the flow of fuel flowing in the fuel supply passage 10P. A stable fuel supply amount can be secured.
[0035]
The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0036]
(1) FIG. 8 is a half sectional view showing the vicinity of the bellows portion of a fuel conduit according to another embodiment. In FIG. 8, this embodiment is characterized by the shape of the bellows portion 35B. That is, the bellows portion 35B includes a large number of annular protrusions 35Ba arranged in parallel at right angles to the axial direction, and an annular path 46Ba is formed between the annular protrusion 35Ba and the inner pipe 40. Further, the bellows portion 35B is formed with a shaft protrusion 35Bb that connects the annular protrusion 35Ba in the axial direction, and a short-circuit path 46Bb that short-circuits and connects the annular path 46Ba is formed in the shaft protrusion 35Bb. Yes. Each short-circuit path 46Bb is arranged so as to be shifted by 90 ° in the circumferential direction for each stage of the annular path 46Ba, thereby improving the bending workability. According to this configuration, a part of the ventilation path 45B can be configured by the short connection path 46B including the annular path 46Ba and the short circuit path 46Bb.
[0037]
(2) FIG. 9 is an explanatory view for explaining a joining process according to another embodiment. In FIG. 9, after the outer pipe 31C and the inner pipe 40C are formed in separate steps, the inner pipe 40C is inserted into the outer pipe 31C. Then, the outer wall of the inner pipe 40C is welded to the valley portion 35Ca by irradiating the laser beam from the laser irradiation device while focusing on the inner wall of the valley portion 35Ca of the bellows portion 35C. According to this method, since the inner pipe 40C and the outer pipe 31C can be created in separate steps, they can be manufactured by a general-purpose manufacturing apparatus.
[0038]
(3) The outer pipe 31 may be formed in multiple layers, or may be formed in a single layer with a resin material such as PE, unless particularly high barrier properties are required.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an oil supply apparatus according to the present embodiment.
2 is an enlarged cross-sectional view of a part of the filler neck 20 and the fuel conduit 30 of FIG.
FIG. 3 is an enlarged cross-sectional view of a main part of the fuel conduit 30 of FIG.
4 is an enlarged cross-sectional view of an outer pipe 31 and an inner pipe 40. FIG.
FIG. 5 is a cross-sectional view of the vicinity of a pipe connection body 50 of a fuel tank FT.
FIG. 6 is an explanatory view for explaining an apparatus for producing a fuel conduit 30;
7 is a schematic configuration diagram illustrating an extrusion device 62 and a mold 71. FIG.
FIG. 8 is a half sectional view showing the vicinity of a bellows portion of a fuel conduit according to another embodiment.
FIG. 9 is an explanatory diagram for explaining a joining process according to another embodiment.
[Explanation of symbols]
10. . . Fuel supply device 10P. . . Fuel supply passage 20. . . Filler neck 20P. . . Injection passage 21. . . Neck body 21a. . . Inlet 21b. . . Outlet 22. . . Neck connection 22a. . . Annular projection 24. . . Mounting bracket 25. . . Seal member 30. . . Fuel conduit 31. . . Outer pipe 31A. . . First extruded tubular body 31C. . . Outer pipe 31a. . . Inner layer 31b. . . Barrier layer 31c. . . Outer layer 31d. . . Pipe connection end 31e. . . Pipe connection ends 32, 33, 34. . . Straight pipe portions 35a, 36a. . . Tanibe 35, 36. . . Bellows 35B. . . Bellows 35C. . . Bellows 35Ba. . . Annular projection 35Bb. . . Shaft protrusion 35Ca. . . Tanibe 40. . . Inner pipe 40A. . . Second extruded tube 40C. . . Inner pipe 40P. . . Tube passage 43. . . Introducing section 45. . . Ventilation channel 45B. . . Air passage 46. . . Connection path 46B. . . Connection path 46Ba. . . Annular path 46Bb. . . Short circuit 50. . . Pipe connector 51. . . Tube body 52. . . Cylindrical portion 52a. . . Passage 52b. . . Annular protrusion 53. . . Flange portion 53a. . . Welding section 55. . . Tube support 56. . . Cylindrical support 56a. . . Annular protrusion 57. . . Flange portion 58. . . Discharge unit 58a. . . Open end 60. . . Manufacturing apparatus 62. . . Extrusion device 63. . . Die 63a. . . Projections 64a, 64b, 64c, 64d. . . Resin supply mechanisms 65a, 65b. . . Compressed gas supply 66. . . Control device 70. . . Mold unit for molding 71. . . Mold 71A. . . Mold 71B. . . Mold 71a. . . Bellows molding surface 71b. . . Straight pipe forming surface 80. . . Transport device 94. . . Laser irradiation device CP. . . Fuel cap FT. . . Fuel tank FTa. . . Tank opening IB. . . Inlet box VP. . . Body panel

Claims (5)

A fuel conduit comprising an outer pipe (31) and an inner pipe (40) disposed in the outer pipe (31) with a gap serving as a ventilation path (45),
The outer pipe (31) has a bellows part (35) in at least a part thereof,
The inner pipe (40) has at least a part of its cylindrical outer peripheral surface joined to the inner wall of the valley of the bellows part (35), and between the bellows part (35) and the inner pipe (40). Forming a connection path (46) communicating with the vent path (45) between the outer peripheral surface,
A fuel conduit characterized by. The fuel conduit according to claim 1, wherein
The said connection path (46) is a fuel conduit | pipe comprised by forming the said bellows part (35) in a helical shape. The fuel conduit according to claim 1, wherein
The connection path (46) is formed from a short-circuit path (46Bb) in which the bellows part (35B) is formed in a large number of annular paths (46Ba) arranged in the axial direction, and the annular path (46Ba) is short-circuited. Constructed fuel conduit. A method of manufacturing a fuel conduit according to claim 1,
A first extruded tube (30P) for forming the outer pipe (31) is extruded, and a second for forming the inner pipe (40) in the first extruded tube (31A). An extrusion process of extruding the extruded tube body (40A) of
The first extruded pipe body (71a) is conveyed by the bellows molding surface (71a) of the mold (71) while conveying the molded mold (71) disposed on both sides of the extruded first extruded pipe body (31A). 31A), the bellows part (35) is shaped, and a compressed gas is blown into the second extruded tube body (40A) so that the outer wall of the second extruded tube body (40A) is connected to the bellows part (40A). A shaping step of closely contacting the inner wall of the valley portion (35a) of 35) and forming the air passage (45) therebetween,
A fuel conduit manufacturing method comprising: The method of manufacturing a fuel conduit according to claim 4,
A method of manufacturing a fuel conduit, wherein after the shaping step, the fuel conduit is heated and bent along a recess of a mold to bend into a predetermined shape.

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