JP2012197806A - Fuel tube and connector for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both high fuel resistance according to fuel in use and fuel permeability resistance by an inexpensive configuration in a fuel tube 1 formed by welding and joining a connector 3 to the end of a resin-made tube body 2 composed by radially laminating a plurality of layers 4-7.SOLUTION: An annular tube insertion groove 11 is formed on axial one end surface of the connector 3, wherein the end of a tube body 2 is inserted and spin-welding thereto. The tube insertion groove 11 is configured to have an outer peripheral side wall surface 13 whose diameter is reduced from the opening side to the depth side of the groove 11, an inner peripheral side wall surface 12 located on the radial inside of the outer peripheral side wall surface 13 and whose diameter is substantially constant from the opening side to the depth side, and a bottom wall surface 15 connected to the end on the depth side of the inner peripheral side wall surface 12 and whose diameter is increased from the opening side to the depth side.

Description

  The present invention belongs to a technical field related to a fuel tube in which a connector is welded to an end portion of a resin tube main body formed by laminating a plurality of layers in a radial direction, and the connector.

  Conventionally, as a fuel tube having a tube body formed by laminating a plurality of layers in the radial direction and a connector for connection, for example, a connector in which the tube body is press-fitted and fixed, or a connector and a tube body are welded It is known that it is integrally fixed.

  For example, in the fuel tube shown in Patent Document 1, the end portion of the fuel tube is press-fitted and fixed to a nipple having a plurality of protrusions on the outer peripheral portion. Further, in the fuel tube shown in Patent Document 2, the tube main body is constituted by three layers laminated in the radial direction, and the innermost layer and the outermost layer are welded to the tapered portion provided in the connector by spin welding. I have to.

  The innermost layer of the tube body is made of a conductive resin as shown in Patent Document 3, for example. As a result, the electric charge accumulated due to the friction between the innermost layer and the fuel is prevented from being discharged and igniting the fuel.

Special Table 2000-146063 JP-T-2002-504980 JP 2010-54055 A

  However, in the fuel tube shown in Patent Document 1, since the end of the tube body is press-fitted into the connector, fuel is likely to leak from the press-fitted portion (end of the fuel tube), and the fuel permeation resistance is low. There is a problem. Then, as shown in the said patent document 2, it is possible to prevent the fuel leak from this edge part by welding the edge part of a tube main body to a connector.

  However, in this fuel tube, since the innermost layer melts during welding, it is necessary to increase the thickness of the innermost layer in advance. For this reason, for example, as shown in Patent Document 3, when the resin constituting the innermost layer is made of a relatively expensive conductive material, there is a problem of increasing the product cost. In this fuel tube, since the resin constituting the innermost layer is limited to the resin that can be welded to the connector, the fuel resistance (corrosion resistance, durability) required for the innermost layer may not be ensured. There is room for improvement in terms of fuel permeability and fuel resistance.

  The present invention has been made in view of such points, and an object of the present invention is to improve fuel permeability with an inexpensive configuration while ensuring high fuel resistance according to the fuel used. There is to do.

  The invention of claim 1 is directed to a fuel tube formed by welding a connector to an end portion of a resin tube body formed by laminating a plurality of layers in the radial direction. And the connector has an annular recess to which the end of the tube body is inserted and welded, and the annular recess has an outer peripheral side wall surface whose diameter decreases from the opening side to the back side of the recess, It is located on the radially inner side of the outer peripheral side wall surface, and is connected to the inner peripheral side wall surface having a substantially constant diameter from the opening side to the inner side, and to the end on the inner side of the inner peripheral side wall surface. It is assumed that it has a back side wall surface whose diameter increases toward the back side.

  In the invention of claim 2, in the invention of claim 1, the tube body is composed of at least three layers, and the outermost layer is welded to the outer peripheral side wall surface of the annular recess, and the innermost layer and the outermost layer, It is assumed that one layer between the two is welded to the back side wall surface of the annular recess.

  According to the structure of Claim 1 and Claim 2, the outermost layer of the tube main body and one layer between the outermost layer and the innermost layer can be welded to the connector.

  That is, for example, when joining the tube body to the connector by spin welding, insert the end of the tube body into the annular recess of the connector and push it from the opening side to the back side while rotating the tube body relative to the connector. The contact surface between the tube body and the connector is melted by frictional heat. At this time, since the outer peripheral side wall surface of the annular recess is formed so that the diameter decreases from the opening side toward the inner side, the outermost layer of the tube body contacts the outer peripheral side wall surface, and the contact surface is melted by friction. To do. Thus, the outermost layer can be welded to the connector. On the other hand, since the inner peripheral side wall surface of the annular recess is formed so that the diameter becomes substantially constant from the opening side toward the back side, the innermost layer of the tube main body (particularly the end on the back side of the innermost layer) Contact with the inner peripheral side wall surface is suppressed. However, since the inner side wall has a rear side wall surface that increases in diameter from the opening side toward the inner side, the inner side wall end portion contacts the inner side wall surface. To do. As a result, the end on the back side of the innermost layer is shaved as if chamfered by the inner wall surface, and as a result, one layer located outside the innermost layer (for example, a layer adjacent to the innermost layer) Comes into contact with the back side wall surface. Therefore, if this one layer is made of a resin that can be welded to the connector, the contact portion between this one layer and the back side wall surface is melted by friction, and the one layer is welded to the back side wall surface. be able to.

  Therefore, the outermost layer and the one layer can be welded to the connector without welding the innermost layer to the connector, whereby the fuel from the end of the tube main body (the connection portion between the tube main body and the connector). Leakage can be reliably prevented. Further, since the resin constituting the innermost layer is not limited to the resin having weldability with the connector, the innermost layer can be made of a resin having excellent fuel resistance according to the fuel used. Further, since the innermost layer is not welded to the connector, it is not necessary to increase the thickness in advance. Therefore, even when the resin constituting the innermost layer is made of a relatively expensive conductive resin, the increase in cost can be suppressed as much as possible.

  In the invention of claim 3, in the invention of claim 2, the tube body is composed of at least four layers, and is located between the outermost layer and the one layer and has a fuel permeation resistance barrier. Includes layers.

  According to this configuration, the fuel permeation resistance can be further improved by sealing the barrier layer between the outermost layer welded to the connector and the one layer.

  In the invention of claim 4, in the invention of claim 2 or 3, the outermost layer and the one layer of the tube body are made of PA11 or PA12.

  According to this configuration, the fuel tube manufacturing cost can be reduced by adopting PA11 or PA12, which is an inexpensive and excellent processable resin, as the resin constituting the outermost layer and the one layer.

  According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, the connector is made of the same resin as that constituting the outermost layer and the one layer.

  According to this configuration, it is possible to enhance the bondability between the outermost layer and the one layer and the connector as much as possible.

  According to the invention of claim 6, in the invention of any one of claims 1 to 5, the innermost layer of the tube body is made of a fluororesin.

  According to this configuration, it is possible to improve fuel resistance (durability, corrosion resistance, etc.) against alcohol fuel and the like by adopting a fluorine-based resin as the resin constituting the innermost layer. Many fluororesins have a higher melting point (low heat melting property) than nylon resins, but in the present invention, it is not necessary to weld the innermost layer to the connector as described above. Such a high melting point resin can be used for the innermost layer. Furthermore, since the fluororesin is also excellent in resistance to sour gasoline produced by oxidation of gasoline, the sour gasoline resistance of the fuel tube can be improved.

  According to a seventh aspect of the invention, in the invention according to any one of the first to sixth aspects, the inner peripheral edge of the rear side wall surface of the annular recess is connected to the inner peripheral side wall surface, and the outer peripheral edge is the outer peripheral side wall surface. And a burr accommodating portion surrounded by the outer peripheral side wall surface, the back side wall surface, and the back side end surface of the tube body is provided at the end on the back side of the annular recess. To do.

  According to this configuration, for example, when the tube main body is spin welded to the connector by spin welding, burrs generated at the contact portion between the tube main body and the connector can be accommodated in the burr accommodating portion. Further, by forming the burr accommodating portion at the end on the back side of the annular recess, it is possible to reliably prevent the burr generated during spin welding from entering the fuel passage.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the bonding force of the tube main body in the pulling direction with respect to the connector is greater than the breaking load in the pulling direction of the tube main body. To do.

  Thus, the fuel that leaks from the connecting portion of the tube body by firmly bonding the connector and the tube body so that the joining force of the tube body to the connector exceeds the breaking load of the tube body in the drawing direction. Can be reduced as much as possible.

  The invention of claim 9 is directed to a connector that is welded to the end of the tube. And it has the annular recessed part by which the edge part of the said tube is inserted and spin-welded, and the said annular recessed part has an outer peripheral side wall surface where a diameter becomes small toward the back | inner side from this opening side, and this outer peripheral side wall surface Is connected to the inner peripheral side wall surface having a substantially constant diameter from the opening side to the inner side, and to the inner end of the inner peripheral side wall surface, and from the opening side to the inner side. And a rear side wall surface having a large diameter.

  According to this configuration, the same effect as that of the first aspect of the invention can be obtained.

  As described above, according to the present invention, the annular recess for inserting a tube formed in the connector has an outer peripheral side wall surface whose diameter decreases from the opening side to the inner side of the concave portion, and the diameter of the outer peripheral side wall surface. It is located on the inner side in the direction and is connected to the inner peripheral side wall surface whose diameter is substantially constant from the opening side to the inner side, and to the inner end of the inner peripheral side wall surface. By having the rear side wall surface with a large value, fuel permeation resistance can be improved with an inexpensive configuration while ensuring high fuel resistance according to the fuel used.

It is sectional drawing perpendicular | vertical to the axial center direction which shows the tube main body of the fuel tube which concerns on embodiment of this invention. It is sectional drawing along the axial center direction of a fuel tube which shows the joining structure of a tube main body and a connector. It is a side view of a connector. It is the IV-IV sectional view taken on the line of FIG. It is an expanded sectional view which shows the tube insertion groove part of a connector. FIG. 6 is a view corresponding to FIG. 5 showing a conventional connector. It is explanatory drawing for demonstrating the permeation | transmission mechanism of a fuel. FIG. 6 is a view corresponding to FIG. 5 showing another embodiment. FIG. 6 is a view corresponding to FIG. 5 showing another embodiment.

  1 and 2 show a fuel tube 1 according to an embodiment of the present invention. The fuel tube 1 is used, for example, as a connection between an automobile fuel injection pipe and a fuel tank, or a connection pipe that sends fuel to an engine. The fuel tube 1 can be used not only for liquid fuel but also for gaseous fuel.

  As shown in FIG. 2, the fuel tube 1 has a resin tube main body 2 and a connector 3 (for connection) for connecting the tube main body 2 to piping or the like. The tube body 2 and the connector are integrated by spin welding (a kind of friction welding).

  The tube body 2 is a circular tube having an inner diameter and an outer diameter that are substantially constant from one end side to the other end side, and is composed of four layers 4 to 7 stacked in the radial direction. These four layers 4 to 7 are laminated in the order of the innermost layer 4, the inner layer 5, the intermediate layer 6, and the outermost layer 7 from the radially inner side to the radially outer side. The intermediate layer 6 has fuel permeation resistance, and two layers of an inner layer 5 and an innermost layer 4 are formed on the inner side in the radial direction of the intermediate layer 6.

  The connector 3 has a tube insertion groove 11 into which the tube body 2 is inserted and spin welded. As will be described in detail later, the tube body 2 is joined to the connector 3 by welding at least the outermost layer 7 and the inner layer 5 to the wall surface in the groove 11.

The outermost layer 7 is preferably formed of an aliphatic thermoplastic resin having heat melting property,
Specifically, it can be formed of, for example, a nylon resin (for example, PA11, PA12, PA6, PA66, PA99, PA610, PA6 / 66, PA6 / 12, etc.). The melting point of the outermost layer 7 is more preferably 240 ° C. or lower. In this way, the outermost layer 7 can be welded to the connector 3 by spin welding by forming the outermost layer 7 from a heat-meltable nylon resin (PA resin). The PA resin satisfies the performance required for the outermost layer 7 from the viewpoints of chemical resistance, weather resistance, flexibility, strength, toughness, and the like, and is also preferable as a constituent resin of the outermost layer 7 from this point. The resin used for the outermost layer 7 is preferably the same resin as that used for the connector 3. Thereby, the joining property by the spin welding of the outermost layer 7 and the connector 3 can be improved.

  The inner layer 5 is preferably formed of an aliphatic thermoplastic resin having heat melting properties, like the outermost layer 7. The inner layer 5 is preferably formed of, for example, a relatively inexpensive nylon-based thermoplastic resin. For example, polyamide (PA) 11, polyamide 12, polyamide 6, polyamide 66, polyamide 99, polyamide 610, polyamide 26, polyamide 46, Polyamide 69, Polyamide 611, Polyamide 612, Polyamide 6T, Polyamide 6I, Polyamide 912, Polyamide TMHT, Polyamide 9T, Polyamide 9I, Polyamide 9N, Polyamide 1010, Polyamide 1012, Polyamide 10T, Polyamide 10N, Polyamide 11T, Polyamide 11I, Polyamide 11N , Polyamide 1212, polyamide 12T, polyamide 12I, polyamide 12N, polyamide MXD6, polyamide PACM12, polyamide dimethyl PACM1 Aliphatic polyamides and aromatic polyamides and the like and the like, and at least one polyamide, copolymers thereof using several kinds of raw material monomers of these polyamides. These can use 1 type (s) or 2 or more types. From the viewpoint of heat resistance, mechanical strength and interlayer adhesion of the tube body 2, the polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide 6T, polyamide 6N, polyamide 9T, Polyamide 9N, polyamide 12T, and polyamide 12N are preferred, and among these, polyamide 11 and polyamide 12 are even more preferred. The melting point of the resin constituting the inner layer 5 is more preferably 240 ° or less. The inner layer 5 and the outermost layer 7 do not necessarily need to be made of the same resin material.

  The intermediate layer 6 has a function as a barrier layer for preventing fuel leakage mainly from the peripheral side surface of the fuel tube. The intermediate layer 6 may be formed of any resin as long as it has excellent fuel permeation resistance. For example, a resin having a high barrier property that can be selected from the following fluorine-based resins and the above-mentioned nylon-based resins, Other saponified ethylene / vinyl acetate copolymer (EVOH), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyarylate (PAR), polyethylene terephthalate (PET), polyacetal (POM), polyphenylene oxide (PPO), polysulfone (PSF), polyethersulfone (PES), polythioethersulfone (PTES), polyetheretherketone (PEEK), polyallyletherketone (PAEK), polyacrylonitrile (PAN) ), Polymetac Ronitrile, acrylonitrile / styrene copolymer, methacrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer (ABS), methacrylonitrile / styrene / butadiene copolymer (MBS), polymethyl methacrylate (PMMA) ), Polyethyl methacrylate (PEMA), poly to bil alcohol (PVA), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), thermoplastic polyimide (PI), polyamideimide (PAI), polyetherimide (PEI) ), Polysulfone (PSU), high density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE), polypropylene (PP), ethylene / propylene copolymer (EPR), ethylene / butene copolymer (EBR), ethylene / acetic acid Bi Copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), ethylene / methyl acrylate copolymer (EMA), ethylene / methyl methacrylate copolymer (EMMA), ethylene / ethyl acrylate (EEA), and the like are included, and these may have an adhesive functional group, or one or two or more may be polymerized. Furthermore, from the viewpoints of heat resistance, mechanical strength, and interlayer adhesion of the tube body 2, aliphatic polyamides having high barrier properties such as fluororesin, polyamide 46, polyamide 66, polyamide 610, polyamide 612 described later, and polyamide are used. Aromatic polyamides with high barrier properties such as 6T, polyamide 6N, polyamide 9T, polyamide 9N, polyamide 12T, polyamide 12N, ethylene / vinyl acetate copolymer saponified product (EVOH), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyethylene terephthalate (PET), polyethersulfone (PES), and polyetheretherketone (PEEK) are more preferable, and among these, fluorine-based resins are even more preferable.

  The innermost layer 4 forms a fuel passage 8 through which fuel passes. Since the inner peripheral surface of the innermost layer 4 is in direct contact with the fuel flowing in the fuel passage 8, there is a risk that the charge accumulated by friction between the two will ignite the fuel at the time of discharge. Therefore, in order to prevent this, the innermost layer 4 is preferably formed of a resin having conductivity. However, when the fuel flowing through the fuel tube 1 has low flammability, the innermost layer 4 does not necessarily need to be made of a conductive material.

  In addition, since the innermost layer 4 is directly exposed to the fuel as described above, it is preferable to form the innermost layer 4 with a resin excellent in resistance to fuel (fuel deterioration resistance, fuel corrosion resistance, etc.). Therefore, for example, when an alcohol fuel having excellent environmental properties is used as the fuel, the innermost layer 4 is preferably formed of a fluorine-based resin. Fluorine-based resins have better fuel permeation resistance than PA resins, and are preferable from the viewpoint of fuel permeation resistance. Examples of the fluororesin include tetrafluoroethylene / perfluoroalkyl ether copolymer (PFA), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene / tetrafluoroethylene copolymer (ETFE), and polyfluoride. Vinyl fluoride (PVF), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene / chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride / chlorotrifluoroethylene Copolymer, chlorotrifluoroethylene / tetrafluoroethylene copolymer, vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene / hexaf Olefin copolymer, vinylidene fluoride / tetrafluoroethylene copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / pentafluoropropylene copolymer, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride Copolymer (THV), vinylidene fluoride / pentafluoropropylene / tetrafluoroethylene copolymer, vinylidene fluoride / perfluoroalkyl vinyl ether / tetrafluoroethylene copolymer, etc., and at least one fluorine-containing monomer It is a polymer having a repeating unit derived from a body, and one kind or two or more kinds of the polymers may be used. The innermost layer 4 is not necessarily welded to the connector 3, and at least the outermost layer 7 and the inner layer 5 may be welded to the connector 3. Therefore, the resin constituting the innermost layer 4 may be a resin having a higher melting point than the temperature condition for welding the tube body 2 and the connector 3.

  The connector 3 is an integrally molded product made of a resin, and is preferably formed of an aliphatic thermoplastic resin having heat melting properties in order to ensure weldability with the outermost layer 7 and the inner layer 5. Specifically, it is preferably formed of a nylon resin (for example, PA11, PA12, PA6, PA66, PA99, PA610, PA6 / 66, PA6 / 12, etc.). The connector 3 is more preferably formed of the same resin as that constituting the inner layer 5 and the outermost layer 7.

  As shown in FIGS. 2 to 4, the connector 3 is a so-called quick connector having a substantially L shape in which a fuel pipe (not shown) is detachable, and a fuel passage 16 communicating with the inside of the tube main body 2 is provided in the connector 3. Is formed.

  Specifically, the connector 3 includes a tube insertion portion 10 into which the tube main body 2 is inserted (fitted) and spin-welded, and a pipe attachment portion 21 that extends perpendicularly from the tube insertion portion 10 and to which a fuel pipe is attached. It has.

  The tube insertion part 10 has a bottomed cylindrical tube insertion groove part 11 (see FIG. 5) that opens to one side in the axial direction. The tube insertion groove 11 has an annular shape when viewed from the axial direction. An annular burr accommodating portion 14a is formed at the opening side end of the tube insertion groove 11 so as to surround the outer periphery thereof. The burr accommodating portion 14 a is a dish-shaped recess that opens to the tube body 2 side, and is formed continuously to the tube insertion groove portion 11. The burr accommodating portion 14a is not necessarily provided.

  The tube insertion groove 11 is a bottomed annular recess opened to the tube body 2 side, and has an inner peripheral side wall surface 12, an outer peripheral side wall surface 13, and a bottom wall surface 15 as a back side wall surface.

  The interval between the inner peripheral side wall surface 12 and the outer peripheral side wall surface 13 in the tube insertion groove 11 is formed so as to gradually decrease from the opening side toward the back side. The outer peripheral side wall surface 13 is formed in a tapered surface shape whose diameter decreases from the opening side of the tube insertion groove 11 toward the back side (bottom side), while the inner peripheral side wall surface 12 extends from the opening side to the back side. Thus, it is formed in a cylindrical surface having a substantially constant diameter. The maximum value of the outer diameter of the tube insertion groove 11 (distance from the axial center of the connector 3 to the outer peripheral side wall surface 13) is the outer diameter of the insertion side end of the tube main body 2 before the tube main body 2 is spin welded. Bigger than. The minimum value of the outer peripheral diameter of the tube insertion groove 11 is smaller than the outer diameter of the insertion side end of the tube main body 2 in a state before the tube main body 2 is spin welded. The inner peripheral diameter (distance from the axial center of the connector 3 to the inner peripheral side wall surface 12) of the tube insertion groove 11 is larger than the inner diameter of the insertion side end of the tube main body 2 before the tube main body 2 is spin welded. Slightly small.

  The bottom wall surface 15 of the tube insertion groove 11 has a tapered surface shape (conical surface shape) whose diameter increases from the opening side toward the back side. The inclination angle α formed by the bottom wall surface 15 with respect to the axial direction of the tube insertion groove 11 is larger than the angle β formed by the outer peripheral side wall surface 13 with respect to the axial direction. At the bottom (back end) of the tube insertion groove 11 is provided a burr accommodating portion 14b that accommodates burrs generated when welding the tube body 2 to the connector. The burr accommodating part 14b consists of the part enclosed by the bottom wall surface 15, the outer peripheral side wall surface 13, and the end surface of the tube main body 2 (refer FIG. 2). The inclination angle α of the bottom wall surface 15 is preferably small from the viewpoint of securing the burr accommodating portion 14b, but if it is too small, the tube body 2 is stroked from the opening side of the tube insertion groove portion 11 to the back side during spin welding described later. Even if it is made to do, since the innermost layer 4 is not shaved much by the bottom wall surface 15, the inner layer 5 cannot be welded (contacted) to the bottom wall surface 15. Therefore, the inclination angle α needs to be an appropriate angle that can achieve both the securing of the burr accommodating portion 14b and the weldability of the inner layer 5 to the bottom wall surface 15. Specifically, the taper angle α is preferably within a range of 40 ° to 50 °, for example, and is 45 ° in the present embodiment.

  Hereinafter, a procedure for spin welding the tube body 2 and the connector 3 will be described. First, the end of the tube main body 2 is inserted into the tube insertion groove 11 of the connector 3, and the tube main body 2 is set in a state in which the end on the back side is in contact with the bottom wall surface 15. Then, after the setting of the tube main body 2 is completed, the connector 3 is rotated around its axis center at a predetermined number of revolutions (in this embodiment, while pushing the tube main body 2 from the opening side of the tube insertion groove 11 toward the back side. When the rotation is performed at 2000 rpm, the contact surface between the tube body 2 and the connector 3 is melted by frictional heat, and the melted contact surface is solidified to weld the tube body 2 to the connector 3. Here, in this embodiment, since the outer peripheral side wall surface 13 of the tube insertion groove 11 is formed into a tapered surface as described above, the outer peripheral surface of the tube body 2 contacts the outer peripheral side wall 13 of the tube insertion groove 11. And welded. Most of the burrs generated at this time are discharged to the burr accommodating portion 14 a located on the outer peripheral side of the insertion groove portion 11.

  On the other hand, the inner peripheral side wall surface 12 of the tube insertion groove portion 11 is formed in a cylindrical surface shape having a substantially constant diameter as described above, so that the innermost layer 4 of the tube body 2 and the inner peripheral side wall surface of the insertion groove portion 11 are formed. Contact with 12 is suppressed. However, since the innermost layer 4 of the tube body 2 is pressed against the tapered bottom wall surface 15 by pushing the tube body 2 into the inner side of the groove 11, the contact portion of the innermost layer 4 with the bottom wall surface 15 is chamfered. As a result, the inner layer 5 adjacent to the innermost layer 4 comes into contact with the bottom wall surface 15. As a result, the inner layer 5 is melted by contact friction with the bottom wall surface 15 and welded to the bottom wall surface 15. The burr generated at this time is mainly accommodated in the burr accommodating portion 14b located at the innermost portion of the tube insertion groove portion 11. The pushing amount of the tube body 2 may be an amount sufficient to bring the inner layer 5 into contact with the bottom wall surface 15 and is set to 2 mm in the present embodiment.

  As described above, in this embodiment, even if the innermost layer 4 cannot be welded to the connector 3, the inner layer 5 adjacent to the innermost layer 4 can be welded to the connector 3. It is possible to reliably prevent fuel leakage from the connecting portion.

  In addition, since it is no longer necessary to weld the innermost layer 4 to the connector 3, the range of resins that can be used for the innermost layer 4 is widened. Therefore, the inner layer 4 has fuel resistance (corrosion resistance, durability) according to the fuel used. In other words, it is possible to achieve both fuel permeation resistance and fuel resistance. Moreover, since it is not necessary to increase the thickness in advance in preparation for melting of the innermost layer 4, even when a relatively expensive conductive resin is used as the resin constituting the innermost layer 4, the increase in cost is suppressed as much as possible. Can do.

  Further, since the portion of the innermost layer 4 that has been cut off is mixed into the welded portion between the inner layer 5 and the bottom wall surface 15, for example, when the innermost layer 4 is made of a conductive material as a countermeasure against discharge, the energization path Can be ensured and discharge can be promoted.

  Moreover, in the said embodiment, the burr | flash accommodating part 14b was formed in the bottom part (back side edge part) of the tube insertion groove part 11, and the burr | flash which generate | occur | produced at the time of the spin welding to the connector 3 of the tube main body 2 is a fuel passage. It can be reliably prevented from being discharged into the inside 8. Thereby, it is possible to reliably prevent the burrs from being mixed into the fuel.

  Next, although an Example (refer Table 1) is described concretely, this invention is not limited to this.

Example 1
As the resin constituting the innermost layer 4, conductive EFEP (for example, Daikin Industries, Ltd. grade material: RP5000AS), which is a conductive fluorine-based resin, is adopted, and as the resin constituting the inner layer 5, an aliphatic thermoplastic resin is used. A certain PA12 (for example, Daicel Evonik grade material: LX9011) is adopted, a non-conductive EFEP which is a fluororesin is adopted as a resin constituting the intermediate layer 6, and a resin constituting the outermost layer 7 is heated. PA12, which is an aliphatic thermoplastic resin having meltability, is employed.

(Example 2)
As the resin constituting the innermost layer 4, conductive EFEP is adopted as in the first embodiment, and as the resin constituting the inner layer 5, PA12 is adopted as in the first embodiment, and as the resin constituting the intermediate layer 6, fluorine is used. Non-conductive PVDF, which is a resin, is employed, and PA 12 is employed as the resin constituting the outermost layer 7 as in the first embodiment.

(Example 3)
As the resin constituting the innermost layer 4, conductive polyphenylene sulfide (hereinafter referred to as conductive PPS) is adopted, and as the resin constituting the inner layer 5, PA 12 is adopted in the same manner as in Example 1 to constitute the intermediate layer 6. As the resin to be used, non-conductive EFEP is adopted as in the first embodiment, and as the resin constituting the outermost layer 7, PA 12 is adopted as in the first embodiment. In Example 3, as the conductive PPS, polyphenylene sulfide (PPS) in which carbon black is blended and dispersed at a ratio of 10 parts by mass with respect to 100 parts by mass of polyphenylene sulfide is used.

Example 4
As the resin constituting the innermost layer 4, conductive EFEP is adopted as in Example 1, and as the resin constituting the inner layer 5, PBT / PA12 alloy resin obtained by kneading and melting polybutylene terephthalate (PBT) and PA12 is used. In this case, polybutylene terephthalate (PBT) is adopted as the resin constituting the intermediate layer 6, and PA 12 is adopted as the resin constituting the outermost layer 7. In addition, between the intermediate | middle layer 6 and the outermost layer 7, PBT / PA12 alloy resin is provided by the thickness of 0.05 mm so that both adhesive strength may not be insufficient.

(About layer thickness)
In Examples 1 and 2, the thickness of the innermost layer 4 was 0.10 mm, the thickness of the inner layer 5 was 0.20 mm, the thickness of the intermediate layer 6 was 0.10 mm, and the thickness of the outermost layer 7 was 0.60 mm.

  In Example 3, the thickness of the innermost layer 4 was 0.05 mm, the thickness of the inner layer 5 was 0.20 mm, the thickness of the intermediate layer 6 was 0.1 mm, and the thickness of the outermost layer 7 was 0.65 mm.

  In Example 4, the thickness of the innermost layer 4 was 0.10 mm, the thickness of the inner layer 5 was 0.20 mm, the thickness of the intermediate layer 6 was 0.20 mm, and the thickness of the outermost layer 7 was 0.45 mm.

(Comparative example)
Next, a comparative example (see Table 2) will be specifically described. The fuel tube 1 of Comparative Example 1 has a conventional tube configuration in which the innermost layer has no conductivity and the intermediate layer has fuel permeation resistance (barrier property). Comparative Examples 2 to 5 are comparative examples corresponding to Examples 1 to 4, respectively, in that only the outermost layer 7 of the tube body 2 is welded to the connector 3, and each of the Examples 1 to 4 is used. Is different. As shown in FIG. 6, the connector 3 used in Comparative Examples 2 to 5 has a tapered outer peripheral side wall surface 13 and a cylindrical inner peripheral side wall surface 12 in the same manner as the connector 3 according to this embodiment. However, the bottom wall surface 15 is not inclined. For this reason, in Comparative Examples 2 to 5, only the outermost layer 7 is welded to the connector 3 (outer peripheral side wall surface 13). In each of Comparative Examples 2 to 5, the constituent materials and thicknesses of the respective layers 4 to 7 are the same as those of Examples 1 to 4, and thus detailed description thereof is omitted.

  Comparative Examples 6 to 9 are comparative examples corresponding to Examples 1 to 4, respectively, and are different from Examples 1 to 4 in that the tube body 2 is connected to the connector 3 by press fitting. Yes. In each comparative example 2-5, since the constituent material and thickness of each layer 4-7 are the same as Examples 1-4, the detailed description is abbreviate | omitted.

(Performance evaluation)
Each item described below was evaluated about the said Example and the comparative example. The evaluation results are shown in Tables 1 and 2.
(Initial adhesive strength)
The initial adhesive strength refers to the smallest value among the interlayer adhesive strengths of the layers 4 to 7. In the measurement, the test tube was halved, a 180 ° peel test was performed at a tensile speed of 30 mm / min using a Tensilon universal tester, the peel strength was read, and the value obtained by dividing by the peel cross-section length (width) Was the initial adhesive strength (initial interlayer adhesive strength). This initial adhesive force is preferably greater than 20 N / cm, and more preferably greater than 30 N / cm.
(Adhesive strength 20 days after fuel filling)
The adhesive force 20 days after fuel filling refers to the smallest value among the interlaminar adhesive strengths of the respective layers 4 to 7 as with the initial adhesive force. In the measurement, alcohol / petrol mixed with 90:10 volume ratio of Fuel C (isooctane: toluene = 50: 50 volume ratio) and ethanol in a test tube was sealed at a temperature of 60 ° C. After holding for 20 days, the adhesive strength was determined by the same method as the initial adhesive strength test. Similar to the initial adhesive strength, it is preferably larger than 20 N / cm, more preferably larger than 30 N / cm.
(About fuel permeation)
The fuel permeation amounts V1 to V3 were measured by the following method using a 200 mm long test tube (inner diameter 6 mm, wall thickness 1 mm) with the connector 3 connected to both ends.

  That is, the above-mentioned alcohol / gasoline was sealed in a test tube and the total weight was measured, then placed in an oven at 60 ° C., and the weight change (a) was measured every day. On the other hand, the change in weight (b) of the test tube not containing the alcohol / gasoline was measured in the same manner. This measurement was continued for 20 days, and the change in the weight of the fuel per day was obtained from (a) and (b), and the fuel permeation amount V1 (60 ° C, E10) was obtained.

  Similarly, when pure ethanol was sealed, the change in the mass of the fuel was calculated in the same manner, and this was used as the fuel permeation amount V2 (60 ° C., E100).

Further, in the case of cycle operation in which 10 to 30 ° C. is changed with a constant temperature descending gradient in a cycle of 12 hours, the fuel mass change is calculated in the same manner, and the fuel permeation amount V3 (10 ° C. to 30 ° C. cycle, E10).
(Tube connector pulling force)
With the connector 3 fixed, the tube body 2 was pulled in the direction of pulling out from the connector 3, and a test was performed in which the tensile load was gradually increased. The tensile load at the moment when the tube main body 2 comes out of the connector 3 was taken as the tube connector pulling force.

  Here, “tube cutting” in Table 1 indicates that the tube body 2 did not come out of the connector 3 and was broken when the tensile load was increased. In other words, this means that the joining force in the pulling direction of the tube body 2 to the connector 3 is larger than the breaking load in the pulling direction (length direction) of the tube body 2.

  From the test results in Tables 1 and 2, the following can be seen. That is, comparing Comparative Example 1 and Comparative Example 6 in which the connection method of the connector 3 is the press-fitting method, the comparative example 6 is disadvantageous in terms of fuel permeation resistance because the fuel permeation amounts V1 and V2 are large. I understand. It is considered that the comparative example 6 has a larger amount of volatile fuel leaking from between the inner peripheral surface of the intermediate layer 6 and the outer peripheral surface of the press-fitting portion of the connector than the comparative example 1 because the distance between them is larger. (Refer FIG.7 (b)). On the other hand, in Comparative Example 2 (example in which a welding method is adopted) that has the same tube configuration as that of Comparative Example 6 and differs only in the connection method of the connector 3, the fuel permeation amounts V1 and V2 are higher than those in Comparative Example 1. It can be seen that the fuel permeation resistance is improved by decreasing. From this, it can be seen that by welding the tube main body 2 to the connector 3, leakage from the connection portion between the tube main body 2 and the connector 3 can be reduced.

  Moreover, the direction of Examples 1-4 which welded the outermost layer 7 and the inner layer 5 to the connector 3 compared with Comparative Examples 2-5 which welded only the outermost layer 7 to the connector 3, and fuel permeation amount V1. It can be seen that V3 (particularly the fuel permeation amount V3) decreases. Specifically, for example, in Example 1, it can be seen that the fuel permeation amount V3 is reduced from 1.3 to 0.7 to about half as compared with Comparative Example 2.

  Further, in Examples 1 to 4, the fuel permeation amounts V1 to V3 (particularly the fuel permeation amount V3) are remarkably reduced as compared with Comparative Examples 6 to 9 in which the press-fitting method is adopted as the connection method of the connector 3. I understand that. Specifically, for example, in Example 1, the fuel permeation amount V3 is reduced from 5.8 to 0.7, which is about 1/8, as compared with Comparative Example 6. As described above, in the fuel tube 1 adopting the press-fitting method, the distance between the inner peripheral surface of the intermediate layer 6 and the outer peripheral surface of the press-fitted portion of the connector 3 is increased, and volatile fuel leaks between the two. On the other hand, in this embodiment, as shown in FIG. 7A, the welded portion 19 between the inner layer 5 and the bottom wall surface 15, and the outermost layer 7 and the outer peripheral side wall surface 13 are disposed. It is considered that the fuel can be shut off by two welded portions with the welded portion 17.

  Thus, in the embodiment and the example described above, the inner layer 5 is the bottom of the connector 3 even if the innermost layer 4 of the tube body 2 is not welded to the connector 3 (the inner peripheral side wall surface 12 of the tube insertion groove 11). Since it is welded to the wall surface 15, fuel leakage from the end of the fuel tube 1 can be reliably suppressed. Therefore, the innermost layer 4 does not necessarily need to be made of a resin excellent in weldability with the connector 3, so that the selection range of the resin that can be used for the innermost layer 4 is expanded, and the innermost layer 4 is fuel resistant according to the fuel used. It can be composed of a resin having excellent properties.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiment, but includes various other configurations. That is, in the said embodiment, although the bottom wall surface 15 of the tube insertion groove part 11 is formed in the taper surface shape diameter-expanded toward the back | inner side from the opening side of this groove part 11, it forms in a taper surface shape. There is no need, for example, as shown in FIG. 8, it may be formed in the shape of an arc that protrudes inside the tube insertion groove 11 or may be formed in the shape of an arc that protrudes on the opposite side. You may do it.

  In the above embodiment, the tapered outer peripheral side wall surface 13 is formed over the entire tube insertion groove 11 from the opening side to the back side. As shown in FIG. 9, the tapered outer peripheral side wall surface 13 may be formed only at the back end of the tube insertion groove 11.

  Moreover, in the said embodiment, although the tube main body 2 is joined to the connector 3 by spin welding, it is not restricted to this, For example, you may make it join by ultrasonic welding or vibration welding.

  INDUSTRIAL APPLICABILITY The present invention is useful for a fuel tube in which a connector is welded to an end of a resin tube body formed by laminating a plurality of layers in the radial direction, and the connector, and particularly from four or more layers. Useful for fuel tubes.

1 Fuel tube
2 Tube body
3 Connector
4 innermost layer
5 Inner layer (one layer)
6 Intermediate layer (barrier layer)
7 outermost layer
11 Tube insertion groove (annular recess)
12 Inner wall surface
13 Outer peripheral side wall surface
14b Burr accommodating part
15 Bottom wall (back side wall)

Claims (9)

A fuel tube configured by welding a connector to an end of a resin tube body formed by laminating a plurality of layers in a radial direction,
The connector has an annular recess into which the end of the tube body is inserted and welded,
The annular recess is located on the outer peripheral side wall surface whose diameter decreases from the opening side to the back side of the recess, and on the radially inner side of the outer peripheral side wall surface, and the diameter is substantially constant from the opening side to the back side. A fuel tube comprising: an inner peripheral side wall surface; and a rear side wall surface that is connected to an inner end of the inner peripheral side wall surface and has a diameter that increases from the opening side toward the inner side. . The fuel tube of claim 1, wherein
The tube body is composed of at least three layers, and the outermost layer is welded to the outer peripheral side wall surface of the annular recess, and one layer between the innermost layer and the outermost layer is formed on the rear side wall surface of the annular recess. A fuel tube configured to be welded. The fuel tube according to claim 2, wherein
The tube body is composed of at least four layers, and includes a barrier layer located between the outermost layer and the one layer and having fuel permeation resistance. The fuel tube according to claim 2 or 3,
The outermost layer of the tube body and the one layer are fuel tubes made of PA11 or PA12. The fuel tube according to any one of claims 2 to 4, wherein
The connector is made of the same resin as the resin constituting the outermost layer and the one layer. The fuel tube according to any one of claims 1 to 5,
The innermost layer of the tube body is a fuel tube made of a fluororesin. The fuel tube according to any one of claims 1 to 6,
A fuel tube characterized in that a burr housing portion surrounded by the outer peripheral side wall surface, the back side wall surface, and the back side end surface of the tube body is provided at an end portion on the back side of the annular recess. . The fuel tube according to any one of claims 1 to 7,
The fuel tube according to claim 1, wherein a joining force of the tube body in the pulling direction to the connector is larger than a breaking load in the pulling direction of the tube body. A connector welded to the end of the tube,
Having an annular recess into which the end of the tube is inserted and welded;
The annular recess is located on the outer peripheral side wall surface whose diameter decreases from the opening side to the back side of the recess, and on the radially inner side of the outer peripheral side wall surface, and the diameter is substantially constant from the opening side to the back side. A connector comprising: an inner peripheral side wall surface; and a rear side wall surface that is connected to an inner end of the inner peripheral side wall surface and has a diameter that increases from the opening side toward the inner side.

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