JP2008207761A - Mounting structure of cylindrical member in fuel tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of a cylindrical member in a fuel tank allowing improvement of management property of transmission amount of fuel. <P>SOLUTION: In this mounting structure, the cylindrical member 6 formed with a barrier layer 8 at the inside and formed with a heat-welding layer 7 at the outside is mounted by heat-welding around an opening part 2 of a tank main body 1 made of resin. A part of the barrier layer 8 is inserted into the inside of the tank rather than the opening part 2 on an external surface of the tank main body 1. A gap L between the opening part 2 and the barrier layer 8 is closed by the heat-welding layer 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a structure in which a cylindrical member is attached to a tank body by heat welding in a resin fuel tank.

  In recent years, fuel tanks mounted on automobiles are mainly made of resin type by blow molding from the viewpoint of rust prevention and weight reduction. Normally, the fuel tank has various cylindrical shapes such as a vent valve for leading the fuel evaporative gas in the space above the liquid surface outside the tank and keeping the tank internal pressure constant, and a backflow prevention valve connected to the filler tube. These cylindrical members are often attached by a thermal welding method from the viewpoint of simplification of the manufacturing process and the like.

  FIG. 3 is a cross-sectional explanatory view showing a conventional mounting structure of a cylindrical member in a fuel tank. The cylindrical member 6 is attached around the opening 2 drilled in the tank body 1 of the fuel tank. The cross-sectional structure of the tank body 1 is, for example, a barrier layer represented by EVOH (ethylene vinyl alcohol copolymer) excellent in HC (hydrocarbon) impermeability (to avoid confusion with the cylindrical member side). (A tank barrier layer) 3 is composed of a multilayer structure sandwiched by heat welding layers (also referred to as tank heat welding layers) 4 and 5 capable of heat welding represented by PE (polyethylene).

  On the other hand, the cylindrical member 6 includes a heat welding layer 7 formed as an outer peripheral surface and a barrier layer 8 formed inside thereof. Examples of the material of the heat welding layer 7 and the barrier layer 8 include PE and EVOH, respectively. As indicated by phantom lines, a cylindrical housing 9 that supports, for example, a valve (not shown) may be appropriately formed inside the barrier layer 8. Examples of the material of the cylindrical housing 9 include POM (polyacetal).

The end of the cylindrical member 6 that is abutted around the opening 2 is formed as a joint portion 6a having an enlarged diameter. Only the periphery of the abutting portion of the joint portion 6a is composed of only the heat welding layer 7, and the end portion of the joint portion 6a is abutted around the opening portion 2 and subjected to the heat welding treatment, so that the tubular member 6 is obtained. Is fixed to the tank body 1. A mounting structure similar to the above is described in FIG.
Japanese Patent Laying-Open No. 2005-82013 (FIG. 2)

  In the mounting structure of the tubular member 6 described above, a region allowing the permeation of fuel is formed between the barrier layer 8 and the tank barrier layer 3, and this region is around the end of the joint portion 6 a and the tank heat welding layer 4. Consists of In FIG. 3, the height dimension of the region is indicated by the symbol H. That is, in the mounting structure of FIG. 3, the quality related to the fuel permeation amount is determined by the height dimension H. However, in order to keep the height dimension H constant in mass production of fuel tanks, it is necessary to strictly manage the conditions such as the pressing force of the tubular member 6 and the welding temperature during heat welding. There is a possibility that the height dimension H changes due to a slight difference in conditions.

  Although it seems that the above problem can be solved if the barrier layer 8 is formed up to the lower end of the joint portion 6a, the barrier layer 8 is made of a material that does not take heat weldability into consideration, and therefore the barrier layer 8 having a low deformation rate. There is a possibility that the lower end portion of the steel plate affects the abutting portion between the heat welding layer 7 and the tank heat welding layer 4. From this, it is desirable that the abutting against the tank heat-welding layer 4 is only the heat-welding layer 7 as shown in FIG.

  The present invention has been created to solve such problems, and an object of the present invention is to provide a tubular member mounting structure in a fuel tank that improves the manageability of the fuel permeation amount.

  In order to solve the above problems, the present invention has a structure in which a tubular member having a barrier layer formed on the inside and a heat-welded layer formed on the outside is attached by thermal welding around the opening of the resin tank body. In addition, a part of the barrier layer is inserted inside the tank with respect to the opening on the outer surface of the tank body, and the gap between the opening and the barrier layer is closed by the heat-welded layer. It is set as the attachment structure of the cylindrical member in the fuel tank.

  According to this mounting structure, the fuel permeation region in the axial direction of the cylindrical member is only a region corresponding to the thickness of the heat-welded layer on the tank side, and the fuel permeation region in the radial direction of the cylindrical member is Since the total area is always equal, variation in fuel permeation amount can be reduced.

  According to the present invention, the tubular member mounting structure in the fuel tank is characterized in that a part of the barrier layer is inserted inside the tank with respect to the tank barrier layer of the tank body.

  According to this mounting structure, the fuel permeation region is only the fuel permeation region in the radial direction of the cylindrical member. Since the total area of the permeation region of the fuel in the radial direction of the cylindrical member is always equal, the permeation amount of the fuel is constant.

  According to the present invention, manageability regarding the amount of permeated fuel is improved.

  1 and 2 are explanatory views of the present invention. FIGS. 1 (a) and 1 (b) are cross-sectional views showing the state before and after the attachment of the tubular member to the tank body, and FIG. 2 is the tank body. It is a top view which shows the clearance gap state of an opening part and a cylindrical member (barrier layer).

  In FIG. 1, a cylindrical member 6 is attached around an opening 2 drilled in a tank body 1 of a fuel tank. The cross-sectional structure of the tank body 1 is the same as that shown in FIG. 3. For example, the tank barrier layer 3 represented by EVOH (ethylene vinyl alcohol copolymer) excellent in HC (hydrocarbon) impermeability. Is composed of a multilayer structure sandwiched between tank heat welding layers 4 and 5 capable of heat welding represented by PE (polyethylene). Specifically, an adhesive layer or a reproducing layer is interposed between the tank barrier layer 3 and the tank heat welding layers 4 and 5, respectively, but is omitted in the drawing. These adhesive layers and regeneration layers do not have a barrier function against permeated fuel.

  On the other hand, the cylindrical member 6 includes a heat welding layer 7 formed as an outer peripheral surface and a barrier layer 8 formed inside thereof. Examples of the material of the heat welding layer 7 and the barrier layer 8 include PE and EVOH, respectively. The heat welding layer 7 and the barrier layer 8 are integrally formed by, for example, two-color molding. In some cases, a cylindrical housing 9 formed of POM or the like shown in FIG. 3 is provided inside the barrier layer 8.

  The end of the cylindrical member 6 that is abutted around the opening 2 is formed as a joint portion 6a having an enlarged diameter. In this joint portion 6 a, the barrier layer 8 extends below the lower end of the heat welding layer 7. The outer diameter of the barrier layer 8 is designed to be smaller than the diameter of the opening 2 of the tank body 1.

  As shown in FIG. 1 (b), the cylindrical member 6 having the above configuration has a part of the barrier layer 8 (around the lower end) inserted inside the tank rather than the opening 2 on the outer surface of the tank body 1, Only the weld layer 7 strikes the outer surface of the tank body 1. When the abutting portion is thermally welded in this state, the gap L between the opening 2 and the barrier layer 8 in the radial direction of the tubular member 6 is closed by the heat welding layer 7. FIG. 1B shows a case where the lower end of the barrier layer 8 is positioned at the inner surface level of the tank body 1.

  According to the present invention, the lower end of the barrier layer 8 is inserted into the tank inside at least the opening 2 on the outer surface of the tank body 1, so that the fuel permeates in the height direction (axial direction of the tubular member 6). The region that allows the above is only the region corresponding to the thickness of the tank heat welding layer 4, and the problem of variation in the height dimension H shown in FIG. 3 is reduced. Preferably, a part (lower end) of the barrier layer 8 is inserted into the tank inside the tank barrier layer 3, and in this case, the tank heat welding layer 4 is entirely covered by the barrier layer 8 in the height direction. Therefore, the problem of variation in the height dimension H shown in FIG. 3 does not occur. The problem of the fuel permeation region in the radial direction of the cylindrical member 6 is as follows.

  In the present invention, when the assembling property of the cylindrical member 6 is taken into consideration, it is not a structure in which the barrier layer 8 is press-fitted and fitted into the opening 2, but the radial direction of the cylindrical member 6 as shown in FIG. It is desirable to provide a structure in which the tubular member 6 can be easily temporarily assembled to the tank body 1 so that a sufficient gap L is provided between the opening 2 and the barrier layer 8. When such a large gap L is formed, in addition to the barrier layer 8 being concentrically positioned with respect to the opening 2 as shown in FIG. ), The barrier layer 8 may be located eccentrically with respect to the opening 2.

  However, the value of the total area (indicated by hatching in FIG. 2) of the gap L between the barrier layer 8 and the opening 2 when viewed from the axial direction of the cylindrical member 6 is the same in any case. Therefore, the fuel permeation amount is kept equal in any case.

  As described above, a part of the barrier layer 8 (around the lower end) is inserted into the tank inside the opening 2 on the outer surface of the tank body 1, and the gap L between the opening 2 and the barrier layer 8 is formed by the heat welding layer 7. If the structure is closed, the fuel permeation region in the axial direction of the tubular member 6 is only the region corresponding to the thickness of the tank heat-welded layer 4, and the fuel permeation region (gap in the radial direction of the tubular member 6). With respect to L), since the total area is always equal, variations in the amount of permeated fuel can be reduced when many fuel tanks are manufactured. Thereby, the manageability regarding the permeation | transmission amount of a fuel improves.

  Further, a part (lower end) of the barrier layer 8 is inserted into the tank inside the tank barrier layer 3 (strictly speaking, inside the tank from the boundary surface between the tank thermal welding layer 4 and the tank barrier layer 3). In this case, the fuel permeation region is only the gap F, which is the fuel permeation region in the radial direction of the cylindrical member 6, so that the fuel permeation amount is constant.

  The preferred embodiments of the present invention have been described above. The present invention is applicable to any member attached to the fuel tank as long as it is a cylindrical member having a heat-welded layer and a barrier layer.

It is explanatory drawing which concerns on this invention, (a), (b) is sectional drawing which shows the state before attachment after attachment of the cylindrical member with respect to a tank main body, respectively. It is explanatory drawing which concerns on this invention, and is a top view which shows the clearance gap state between the opening part of a tank main body, and a cylindrical member (barrier layer). It is sectional explanatory drawing which shows the conventional attachment structure of the cylindrical member in a fuel tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tank main body 2 Opening part 6 Cylindrical member 7 Thermal welding layer 8 Barrier layer L Crevice

Claims (2)

A structure in which a tubular member having a barrier layer formed on the inner side and a heat-welded layer formed on the outer side is attached around the opening of the resin tank body by thermal welding,
A part of the barrier layer is inserted inside the tank from the opening on the outer surface of the tank body,
A structure for attaching a cylindrical member in a fuel tank, wherein a gap between the opening and the barrier layer is closed by the heat-welded layer.   2. The tubular member mounting structure for a fuel tank according to claim 1, wherein a part of the barrier layer is inserted inside the tank with respect to the tank barrier layer of the tank body.

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