JP5369080B2 - Fuel tank component joint structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To weld an attachment component with sufficient welding strength while suppressing the amount of HC penetration even if a tank body has a regenerative layer. <P>SOLUTION: In a tank body 10, an inner layer 11, an HC barrier layer 12, a regenerative layer 13, and a heat-weldable layer 14 are arranged from the inner side in this order. An annular wall 15 in which an end face 15a thereof is directed outward of a tank, and the inner peripheral surface 15b thereof forms an opening 16 is formed on the tank body 10 in order to weld a vent valve 20 having an annular HC barrier 23 and a heat-weldable section 24 on the outer side thereof. While the annular HC barrier 23 is aligned to the HC barrier layer 12 exposed to the end face 15a of the annular wall 15, the heat-weldable section 24 is welded to the heat-weldable layer 14 with a first annular weld part 31 around the annular wall 15 and a second annular weld part 32 in the annular wall 15. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a fuel tank component joining structure, and more particularly, to a structure for welding accessory components to an opening of a synthetic resin tank body.

  In recent years, various types of synthetic resin fuel tanks that can be easily reduced in weight and have high productivity have been developed. In general, high density polyethylene (hereinafter referred to as HDPE) used for blow molding has a low hydrocarbon (HC) impermeability (barrier property). It is difficult to use a material having a high barrier property against HC such as an ethylene vinyl alcohol copolymer (hereinafter referred to as EVOH) intervening as a barrier layer in HDPE.

  In this type of synthetic resin fuel tank, when joining accessory parts such as filler necks and vent valves to the tank body, it is necessary to secure the bonding strength and to control the amount of HC permeated from the joint. . As a joint structure that prevents the discontinuity in the barrier layer in order to suppress the amount of HC permeation, the outer wall of the synthetic resin tank body made of a laminate of heat-weldable material such as HDPE and HC barrier material is used. A cut end face in which a bulge portion that protrudes in the direction is formed, the bulge portion is cut along a single plane to form an opening, and the HC barrier material layer and the heat-weldable material layer are concentrically exposed. In addition, there has been proposed an apparatus in which an accessory part is heated and welded with the HC barrier material layer of the accessory part facing each other (see Patent Document 1).

JP 2002-235624 A

  By the way, recently, a recycled material containing a large amount of impurities may be used as a material for the tank body, rather than a pure (less impurities) virgin HDPE. However, since it is difficult to securely join the accessory part to the recycled material, when the recycled material is used, the recycled layer made of the recycled material provided outside the barrier layer is used to reliably weld the accessory part. Further, it is conceivable that a heat-weldable layer made of pure HDPE is provided on the outer side, and accessory parts are welded to the heat-weldable layer.

  However, when the joining structure of the cited document 1 is applied to the fuel tank having the regeneration layer, the area of the heat-weldable layer exposed on the cut end surface formed by cutting the bulging portion is reduced, so that sufficient joining strength is obtained. Can't get.

  The present invention has been made in view of such a background, and even if the tank body is provided with a recycled layer made of recycled material, the HC permeation amount can be suppressed and the accessory parts can be joined with sufficient joining strength. An object of the present invention is to provide a fuel tank component joining structure.

In order to solve the above problems, according to one aspect of the present invention, an inner layer (11) containing fuel, an HC barrier layer (12), a regeneration layer (13) made of a regenerated material, and a heat-weldable layer (14) ) Is a part joining structure of the fuel tank (1) for joining the accessory part (vent valve 20) to the tank body (10) arranged in this order from the inside, and the end face (15a) of the tank body is the tank. The outer peripheral surface (15b) has an annular wall (15) that faces outward and forms an opening (16), and the accessory is disposed at a position that matches the HC barrier layer exposed at the end face of the annular wall. An annular HC barrier portion (23), and a heat-weldable portion (24) disposed outside the HC barrier portion and formed larger than the end surface of the annular wall portion, on the end surface of the annular wall portion Abutting the exposed HC barrier layer In this state, the heat-weldable portion is welded to the heat-weldable layer with at least the first annular weld portion (31) around the annular wall portion and the second annular weld portion (32) on the end face of the annular wall portion. Features.

  According to this configuration, the HC barrier portion is aligned with the HC barrier layer exposed at the end face of the annular wall portion, and the accessory part is in contact with the HC barrier layer, that is, the HC barrier portion is continuous with the HC barrier layer. Alternatively, since the accessory part is joined to the tank body with the HC barrier portion continuing to the HC barrier layer with the molten heat-weldable portion interposed therebetween, the HC permeation area can be reduced and the HC permeation amount can be suppressed. . Also, the heat-weldable part is welded to the heat-weldable layer with the first annular welded part around the annular wall part and the second annular welded part at the end face of the annular wall part. The joining strength of the parts to the tank body can be obtained as desired.

  Further, according to one aspect of the present invention, the melt of the heat-weldable portion is interposed between the HC barrier layer exposed on the end surface of the annular wall portion and the HC barrier portion.

  According to this configuration, the meltable heat-weldable portion is welded to the HC barrier portion and the inner layer in a state of being filled between the HC barrier layer and the HC barrier portion. It is possible to prevent a gap from being generated between the layer and the HC barrier portion to increase the amount of HC permeation, and to further increase the adhesive strength of the accessory to the tank body.

  According to another aspect of the present invention, the first annular welded portion and the second annular welded portion are substantially on the same plane, and are melted during heating between the first annular welded portion and the second annular welded portion. An annular recess (17) for receiving the molten material in the annular wall is formed.

  According to this configuration, since the first annular welded portion and the second annular welded portion are substantially on the same plane, the heater for melting the tank main body and the accessory can be formed into a simple flat plate shape. Further, during melting or welding, a molten material such as a reproduction layer of the annular wall portion is received in the annular concave portion, and this space portion functions as a trap, so that the welding strength of the first annular welded portion is reduced by mixing of the molten material. Can be prevented. Therefore, desired joining strength with respect to the tank body of the accessory can be ensured. Furthermore, since the periphery of the opening of the tank main body has a rib shape, the strength of the attachment part joint can be increased.

  As described above, according to the present invention, even if the tank body is provided with a recycled layer made of recycled material, it is possible to suppress the amount of HC permeation and to join the accessory part to the tank body with sufficient bonding strength.

Sectional drawing of the principal part of the fuel tank which concerns on 1st Embodiment of this invention. Explanatory drawing of the manufacturing procedure of the tank body shown in FIG. Sectional drawing of the principal part of the fuel tank which shows the modification of 1st Embodiment Sectional drawing of the principal part of the fuel tank which concerns on 2nd Embodiment of this invention. Sectional drawing of the principal part of the fuel tank which shows the modification of 2nd Embodiment Sectional drawing of the principal part of the fuel tank which concerns on 3rd Embodiment of this invention. Sectional drawing of the principal part of the fuel tank which shows the modification of 3rd Embodiment

  Hereinafter, an embodiment of a component joining structure of a fuel tank 1 according to the present invention will be described with reference to the drawings.

<< First Embodiment >>
As shown in FIG. 1, the fuel tank 1 includes a tank body 10 and a vent valve 20 as an accessory part joined to the tank body 10 so as to close an opening 16 formed on the upper surface of the tank body 10. ing.

  The tank body 10 is manufactured by blow molding, and in order from the inside, an inner layer 11 made of HDPE that contains fuel, an HC barrier layer 12 made of EVOH, a regeneration layer 13 made of a recycled material mainly composed of HDPE, and HDPE It has a four-layer structure in which the heat-weldable layer 14 is arranged. An adhesive layer (not shown) is formed between the inner layer 11 and the HC barrier layer 12 and between the HC barrier layer 12 and the reproduction layer 13 in order to ensure adhesion between both layers. Since the layer fulfills an auxiliary function of the tank body 10 for realizing a multilayer structure, the adhesive layer is not regarded as a layer here, and the description thereof is also omitted.

  Around the opening 16 of the tank body 10, an annular wall portion 15 is formed in which the end surface 15 a faces the outside of the tank and the inner peripheral surface 15 b forms the opening 16. An annular recess 17 that is recessed inward of the tank as compared with the end face 15 a of the annular wall 15 is formed around the annular wall 15, and a tank is further formed around the annular wall 15 as compared with the annular recess 17. An annular bulging portion 18 bulging outward is formed. The annular bulging portion 18 has the same height as the annular wall portion 15. That is, the outer surface of the annular bulging portion 18 is disposed on the same plane as the end surface 15 a of the annular wall portion 15.

  In the present embodiment, the annular bulging portion 18 bulges outward from the tank as compared with the annular concave portion 17 and the tank even when compared with its peripheral portion (peripheral portion with respect to the joining region with the vent valve 20). Although it is formed so as to bulge outward, it does not need to bulge outward from the tank as compared to the peripheral part, and may have an outer surface that is flush with the outer surface of the peripheral part.

  The vent valve 20 is manufactured by injection molding, and is integrally formed so as to extend from the valve body 21, the lid portion 22 that supports the valve body 21 and closes the opening 16, and extends from the upper surface of the lid portion 22. And a nozzle portion 25 provided for connection with a vent pipe (not shown) to be connected. The lid portion 22 is annularly arranged on the inner side by two-color molding, and is disposed on the outer side with an HC barrier portion 23 made of a material having a high barrier property against HC such as polyamide resin (hereinafter referred to as PA). And a heat-weldable portion 24 made of modified polyethylene or the like, and has a cylindrical shape with a lid having an open lower end. In addition, the nozzle portion 25 is also formed with a material having a high barrier property on the inside by two-color molding and HDPE or the like on the outside.

  The joint surface of the lid portion 22 with the tank main body 10, that is, the lower surface of the cylindrical portion is a single plane along the outer surface of the tank main body 10. Thereby, a space S is formed between the lid 22 and the annular recess 17 of the tank body 10. Further, the HC barrier portion 23 and the heat-weldable portion 24 are concentrically exposed at the joint surface of the lid portion 22 with the tank body 10, and the HC barrier portion 23 is exposed to the end surface 15 a of the annular wall portion 15. 12 is arranged at a position facing (matching) 12.

  The vent valve 20 is configured such that the heat-weldable portion 24 is heated and welded to the tank body 10 in a state where the HC barrier portion 23 is opposed (aligned) to the HC barrier layer 12 exposed on the end surface 15a of the annular wall portion 15 of the tank body 10. It is bonded to the tank body 10 by being welded to the possible layer 14. More specifically, the heat-weldable portion 24 of the vent valve 20 includes a first annular weld portion 31 that is heat-welded to the heat-weldable layer 14 on the outer surface of the annular bulging portion 18 of the tank body 10, and the tank body 10. The end wall 15a of the annular wall portion 15 is welded together with the second annular welded portion 32 that is heat-welded to the heat-weldable layer 14. The space S formed by the annular recess 17 can receive the collapse allowance when the vent valve 20 is heated and welded to the end surface 15a of the annular wall 15 of the tank body 10 and the outer surface of the annular bulge 18. It has become.

  The manufacturing method of this fuel tank 1 is as follows. As shown in FIG. 2, the tank body 10 having a four-layer structure is blow-molded so as to have a dome portion 19 projecting outward of the tank with the annular recess 17 sandwiched inside the annular bulging portion 18, and thereafter The tank body 10 having the annular wall portion 15 is formed by cutting and removing the dome portion 19 according to the height of the outer surface of the annular bulging portion 18. In FIG. 2, illustration of the layers 11 to 14 is omitted, and only the outline of the tank body 10 is shown.

  Next, the end surface 15a of the annular wall portion 15 and the upper surface (outer surface) of the annular bulge portion 18 and the lower surface of the lid portion 22 are heated and melted by a hot plate heater, and the HC barrier layer exposed on the end surface 15a of the annular wall portion 15 is exposed. 12, with the HC barrier portion 23 facing (aligned) with 12, the lid portion 22 is pressed against the end surface 15 a of the annular wall portion 15 and the upper surface of the annular bulging portion 18, and then left to cool in the atmosphere. By doing so, it is possible to obtain a joint structure of the vent valve 20 to the tank body 10 in which the heat-weldable portion 24 is welded to the heat-weldable layer 14 with the first annular weld portion 31 and the second annular weld portion 32.

  According to the fuel tank 1, the vent valve 20 is joined to the tank body 10 with the HC barrier portion 23 facing the HC barrier layer 12 exposed on the end surface 15 a of the annular wall portion 15, whereby the HC barrier material. Therefore, the amount of HC permeation from the joint between the tank body 10 and the vent valve 20 can be reduced. Further, since the heat-weldable portion 24 is welded to the heat-weldable layer 14 with the first annular weld portion 31 on the outer peripheral side of the annular wall portion 15, a bonding area is secured and the vent valve 20 is attached to the tank body 10. The bonding strength can be obtained as desired. Furthermore, since the heat-weldable portion 24 is welded to the heat-weldable layer 14 not only through the first annular weld portion 31 but also through the second annular weld portion 32 located inside the annular shape, the tank body 10 It is possible to further increase the bonding strength with respect to.

  Further, since the annular recess 17 is provided between the first annular welded portion 31 and the second annular welded portion 32 of the fuel tank 1, the first annular welded portion 31 and the second annular welded portion 32 are substantially on the same plane. Even in this case, the recycled material 13 of the annular wall portion 15 and the meltable material of the heat-weldable layer 14 melted at the time of heat welding can escape into the space portion S formed by the annular recess portion 17, so that the HC barrier layer 12 is formed. Since the annular recess 17 functions as a trap, it is possible to prevent the welding strength of the second annular welded portion 32 from being lowered due to the mixing of the molten material, while being able to be brought into close contact with the HC barrier portion 23 of the vent valve 20. The desired bonding strength of the vent valve 20 to the tank body 10 can be ensured. Moreover, since the periphery of the opening 16 of the tank body 10 is formed into a rib shape by the annular wall portion 15 and the annular recess portion 17, the strength of the joint portion of the vent valve 20 can be improved.

<Modification>
Next, with reference to FIG. 3, the modification of the components joining structure of the fuel tank 1 which concerns on the said embodiment is demonstrated. In this embodiment, as shown in (A), in the state before joining, the vent valve 20 has a stepped surface in which the heat-weldable portion 24 projects downward from the HC barrier portion 23 on the joining surface to the tank body 10. As a result, when the lower surface is heated by a flat plate-shaped hot plate heater (not shown), the meltable heat-weldable portion 24 rotates below the HC barrier portion 23 as shown in FIG. It covers the annular end face of the HC barrier portion 23 and is joined to the tank body 10 in this state.

  Therefore, the vent valve 20 is in a state in which the HC barrier portion 23 is aligned with the HC barrier layer 12 exposed on the end face 15a of the annular wall portion 15 and the heat-weldable portion 24 is in contact with the HC barrier layer 12, that is, The HC barrier portion 23 is joined to the tank body 10 in a state of being continuous with the HC barrier layer 12 with the molten heat-weldable portion 24 interposed therebetween.

  Even in such a joining structure, since the thickness t of the discontinuous portion between the HC barrier layer 12 and the HC barrier portion 23, that is, the heat-weldable portion 24 sandwiched between both, is small, the reproduction layer 13 Alternatively, the amount of HC permeated through the heat-weldable layer 14 and permeate out of the tank can be suppressed.

  Further, the meltable heat-weldable portion 24 is welded to the inner layer 11 with the third annular welded portion 33 on the end surface 15a of the annular wall portion 15 in a state of being filled between the HC barrier layer 12 and the HC barrier portion 23. Therefore, it is possible to prevent a gap between the HC barrier layer 12 and the HC barrier portion 23 from being generated due to a processing error or the like and increase the amount of HC permeation, and further increase the adhesion strength of the vent valve 20 to the tank body 10. Can be increased.

<< Second Embodiment >>
Next, the fuel tank 1 according to the second embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same or similar member as 1st Embodiment, and the overlapping description is abbreviate | omitted. The same applies to the following embodiments.

  As shown in FIG. 4, in the present embodiment, the tank body 10 is flat without the annular bulging portion 18 around the annular wall portion 15, and the annular wall portion whose end surface 15 a faces outward from the tank. 15 differs from the first embodiment in that it is higher than the periphery. In other words, the annular recess 17 that is recessed inward of the tank as compared with the end face 15 a is formed in a wider area around the annular wall portion 15 as compared with the lid portion 22.

  On the other hand, the lid portion 22 of the vent valve 20 includes an annular convex portion 26 whose outer peripheral side protrudes downward (toward the inside of the tank), and a joint surface of the lid portion 22 with the tank body 10, that is, a cylindrical portion. Is formed with a step corresponding to the height difference between the end surface 15a of the annular wall portion 15 and the upper surface (outer surface) of the peripheral portion.

  The heat-weldable portion 24 is exposed on the lower side (inner side of the tank) of the lower surface of the lid 22, and the heat-weldable portion 24 is exposed on the outer peripheral side of the higher side (outer side of the tank) of the lower surface of the lid 22. At the same time, the HC barrier portion 23 is exposed on the inner peripheral side.

  The vent valve 20 is a first annular weld on the end surface 15a of the annular wall 15 with the HC barrier portion 23 facing (aligned) with the HC barrier layer 12 exposed on the end surface 15a of the annular wall 15 of the tank body 10. The heat-weldable portion 24 is bonded to the heat-weldable layer 14 together with the portion 31 and the second annular welded portion 32 on the upper surface of the peripheral portion thereof, thereby being joined to the tank body 10.

  The inner peripheral shape of the annular convex portion 26 is larger than the outer peripheral shape of the annular wall portion 15, and an annular space S formed between the annular convex portion 26 and the annular wall portion 15 is formed in the tank body 10. A collapse allowance for heat-welding the lid portion 22 of the vent valve 20 to the end surface 15a of the annular wall portion 15 and the upper surface of the peripheral portion can be received.

  Even if the fuel tank 1 is configured in this way, the HC barrier layer 12 of the annular wall 15 and the HC barrier portion 23 of the vent valve 20 are in a continuous state. The amount of HC permeated from can be reduced. Further, the heat-weldable portion 24 is welded to the heat-weldable layer 14 not only through the first annular welded portion 31 but also through the second annular welded portion 32 inside thereof, thereby ensuring a bonding area and venting. The bonding strength of the valve 20 to the tank body 10 can be obtained as desired.

<Modification>
FIG. 5 shows a modification of the component joint structure of the fuel tank 1 according to the second embodiment. Also in the present embodiment, as in the first embodiment, in the state before joining as shown in (A), the vent valve 20 can be heated and welded on the higher side (outer tank side) of the joining surface to the tank body 10. As shown in (B), when the lower surface is heated by a hot plate heater having a step (not shown) by forming a step surface in which 24 is projected downward from the HC barrier portion 23, The molten heat-weldable portion 24 wraps under the HC barrier portion 23 to cover the annular end surface of the HC barrier portion 23 and is joined to the tank body 10 in this state.

  Therefore, the vent valve 20 aligns the HC barrier portion 23 with the HC barrier layer 12 exposed on the end face 15a of the annular wall portion 15 and is in contact with the HC barrier layer 12, that is, the molten heat-weldable portion 24. The HC barrier portion 23 is joined to the tank body 10 with the HC barrier layer 12 being continuous with the HC barrier layer 12.

  Even if bonded in such a form, as in the modification of the first embodiment, the thickness of the discontinuous portion between the HC barrier layer 12 and the HC barrier portion 23, that is, the heat-weldable portion 24 sandwiched between the two. Since t is small, the amount of HC permeated through the regeneration layer 13 and the heat-weldable layer 14 and permeate outside the tank can be suppressed.

  Further, when heated by a hot plate heater or when the vent valve 20 is pressed, the molten material is pushed out into the space S, and the heat-weldable layer 14 is covered with the regenerating layer 13 and is applied to the end face 15a of the annular wall 15. Although not exposed, the heat-weldable portion 24 of the vent valve 20 is welded to the heat-weldable layer 14 with the first annular welded portion 31 around the annular wall 15, that is, with a desired bonding area. Thus, it is the same as the modification of the first embodiment that a desired bonding strength with respect to the tank body 10 can be ensured.

  Further, the meltable heat-weldable portion 24 is welded to the inner layer 11 with the third annular welded portion 33 on the end surface 15a of the annular wall portion 15 in a state of being filled between the HC barrier layer 12 and the HC barrier portion 23. Therefore, it is possible to prevent a gap between the HC barrier layer 12 and the HC barrier portion 23 from being generated due to a processing error or the like and increase the amount of HC permeation, and further increase the adhesion strength of the vent valve 20 to the tank body 10. The improvement is also the same as the modification of the first embodiment.

«Third embodiment»
As shown in FIG. 6, in this embodiment, the tank body 10 is flat without the annular bulging portion 18 as well as the annular recessed portion 17 around the annular wall portion 15, and the end face 15a is the tank. The annular wall portion 15 facing outward is different from the above embodiment in that it has the same height as its periphery. On the other hand, in the vent valve 20, as in the first embodiment, the joint surface of the lid portion 22 with the tank main body 10 is a single plane along the outer surface of the tank main body 10. The part 23 and the heat-weldable part 24 are concentrically exposed.

  The vent valve 20 is an annular wall that is a substantially continuous region in a state where the HC barrier portion 23 is opposed (aligned) to the HC barrier layer 12 exposed on the end face 15a of the annular wall portion 15 of the tank body 10. The heat-weldable portion 24 is welded to the heat-weldable layer 14 together with the second annular welded portion 32 on the end surface 15a of the portion 15 and the first annular welded portion 31 on the upper surface of the peripheral portion thereof, thereby being joined to the tank body 10. ing.

  Even if the fuel tank 1 is configured in this way, the HC barrier layer 12 of the annular wall 15 and the HC barrier portion 23 of the vent valve 20 are in a continuous state. The amount of HC permeated from can be reduced. Further, the heat-weldable portion 24 is joined with the first annular welded portion 31 that can have a desired joining area, and is also welded to the heat-weldable layer 14 through the second annular welded portion 32 inside thereof. Thus, the bonding strength of the vent valve 20 to the tank body 10 can be obtained as desired.

<Modification>
FIG. 7 shows a modification of the component joint structure of the fuel tank 1 according to the third embodiment. Also in the present embodiment, as in the first and second embodiments, as shown in (A), in the state prior to joining, the vent valve 20 attaches the heat-weldable portion 24 to the HC barrier portion on the joint surface to the tank body 10. As shown in (B), when the lower surface is heated by a flat plate-shaped hot plate heater (not shown), it can be melted and heat-welded. The portion 24 goes under the HC barrier portion 23 to cover the annular end surface of the HC barrier portion 23 and is joined to the tank body 10 in this state.

  Therefore, the vent valve 20 aligns the HC barrier portion 23 with the HC barrier layer 12 exposed on the end face 15a of the annular wall portion 15 and is in contact with the HC barrier layer 12, that is, the molten heat-weldable portion 24. The HC barrier portion 23 is joined to the tank body 10 with the HC barrier layer 12 being continuous with the HC barrier layer 12.

  Even in such a joint structure, as in the modification of the first and second embodiments, discontinuous portions between the HC barrier layer 12 and the HC barrier portion 23, that is, heat welding sandwiched between the two is possible. Since the thickness t of the portion 24 is small, it is possible to suppress the amount of HC permeated through the regeneration layer 13 and the heat-weldable layer 14 and permeate outside the tank. Further, the meltable heat-weldable portion 24 is welded to the inner layer 11 with the third annular welded portion 33 on the end surface 15a of the annular wall portion 15 in a state of being filled between the HC barrier layer 12 and the HC barrier portion 23. Therefore, it is possible to prevent a gap between the HC barrier layer 12 and the HC barrier portion 23 from being generated due to a processing error or the like and increase the amount of HC permeation, and further increase the adhesion strength of the vent valve 20 to the tank body 10. Can be increased.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the invention. For example, in the above embodiment, the tank body 10 has a four-layer structure, but is not limited to a four-layer structure, and may be four or more layers as long as it includes at least these four layers. It should be noted that all the components of the component joining structure of the fuel tank 1 according to the present invention shown in the above embodiment are not necessarily essential, and can be appropriately selected as long as they do not depart from the scope of the present invention. is there.

DESCRIPTION OF SYMBOLS 1 Fuel tank 10 Tank main body 11 Inner layer 12 HC barrier layer 13 Regeneration layer 14 Heat-weldable layer 15 Annular wall part 15a End surface 15b Inner peripheral surface 16 Opening 17 Annular recessed part 20 Vent valve (accessory part)
23 HC barrier portion 24 heat weldable portion 31 first annular welded portion 32 second annular welded portion 33 third annular welded portion

Claims (3)

A fuel tank component joining structure for joining an accessory to a tank body in which a fuel containing inner layer, an HC barrier layer, a regeneration layer made of a regenerated material, and a heat-weldable layer are arranged in this order from the inside,
The tank body includes an annular wall portion with an end surface facing outward from the tank and an inner peripheral surface forming an opening,
The accessory part is disposed at a position aligned with the HC barrier layer exposed at the end surface of the annular wall portion, and is disposed outside the HC barrier portion, from the end surface of the annular wall portion. A heat-weldable portion formed larger than the annular wall portion, and in contact with the HC barrier layer exposed at the end face of the annular wall portion, the heat-weldable portion is at least a first annular portion around the annular wall portion. A fuel tank component joining structure characterized in that a welded portion and a second annular welded portion at an end face of the annular wall portion are welded to the heat weldable layer.   2. The fuel tank component joining structure according to claim 1, wherein a melt of the heat-weldable portion is interposed between the HC barrier layer exposed at the end face of the annular wall portion and the HC barrier portion. . The first annular welded portion and the second annular welded portion are on substantially the same plane;
The annular recess for receiving the molten material of the annular wall portion melted during heating is formed between the first annular weld portion and the second annular weld portion. 2. A fuel tank component joining structure according to 2.

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