JP6533418B2 - Fuel tank - Google Patents

Description

  The present invention relates to a fuel tank for a vehicle.

  Conventionally, a fuel tank for vehicles made of synthetic resin is known. In general, a fuel tank made of synthetic resin has a multilayer structure in which a fuel tank main body is formed of a synthetic resin, includes an inner layer and an outer layer forming the fuel tank main body, and a barrier layer is sandwiched between the inner layer and the outer layer. Are often considered to be

  For example, Patent Document 1 discloses a fuel tank in which a fuel tank upper side wall and a fuel tank lower side wall are formed of a skin layer, an outer main body layer, an outer adhesive layer, a barrier layer, an inner adhesive layer and an inner main body layer. It is disclosed. In the fuel tank, the skin layer, the outer main body layer and the inner main body layer are formed of high density polyethylene (HDPE) or the like. Also, a barrier layer for preventing fuel permeation is formed of an ethylene vinyl alcohol copolymer or the like.

JP, 2014-104920, A

  The fuel tank as disclosed in Patent Document 1 is provided with good impact resistance and rigidity by the outer body layer and the inner body layer being formed of high density polyethylene or the like. A multilayer structure comprising a body layer and a barrier layer formed of high density polyethylene or the like can also be formed with less man-hours by blow molding using a multilayered parison.

  However, conventionally, further weight reduction of the fuel tank is required. As a measure to reduce the weight of the fuel tank, it is possible to adopt a method of reducing the weight per unit area of the fuel tank main body formed of high density polyethylene or the like. However, since the rigidity of the fuel tank main body is proportional to the cube of the thickness of the container wall, it is difficult to secure the high rigidity required for the fuel tank by the method of thinning the wall.

  Therefore, an object of the present invention is to provide a fuel tank that is lightweight but has high rigidity.

In order to solve the above problems, a fuel tank according to claim 1 is a fuel tank having a multilayer structure formed of a synthetic resin, and is formed of a foam layer formed of a foamed resin, and a fiber reinforced resin, A fiber reinforced layer disposed on the inner side and an outer side of the foam layer, and a welding layer formed of a thermoplastic resin and disposed between the foam layer and the fiber reinforced layer on the inner side , The fiber reinforced layer is characterized by having organic fibers embedded in a matrix . The fuel tank according to claim 2 is characterized in that the fiber reinforced layer is formed of polypropylene fibers and a matrix of polyethylene.

According to the present invention, since the fiber reinforced layer is provided, high rigidity is provided with respect to the thickness and weight of the fuel tank body. Further, since the foam layer having a wide range in the selection of the thickness and the bubble rate is provided, it is possible to adjust the thickness of the fuel tank main body while reducing the rigidity and to reduce the coating weight. Furthermore, since the welding layer which becomes a welding margin is provided, high welding strength can be realized in welding which may be difficult due to the foam layer or the fiber reinforced layer. Therefore, it is possible to provide a fuel tank having a foam layer and a fiber reinforced layer and having light weight and high rigidity by utilizing welding by welding. Specifically, the weight per unit area of the fuel tank main body can be halved while maintaining the level of rigidity according to the conventional structure. Moreover, when joining other members to a fuel tank by welding, it becomes possible to obtain high joint strength. By forming the fiber reinforced layer with the organic fiber and the matrix, it is lightweight and flexible, and the oil resistance, strength and the like are improved, and it becomes a layer suitable for welding and molding.

In the fuel tank according to claim 3 , the foam layer is formed of foamed polypropylene, the fiber reinforcing layer is formed of polypropylene fibers and a matrix of polyethylene, and the welding layer is formed of polyethylene. It is characterized by being.

  According to the present invention, since the foam layer is formed of foamed polypropylene, the rigidity is well improved and the risk of leakage due to fuel permeation is further reduced. In addition, since the fiber reinforced layer is formed of polypropylene fibers and a matrix of polyethylene, the rigidity is well enhanced. In addition, since the welding layer is formed of polyethylene, the welding temperature can be made relatively low, and the risk of leakage due to permeation of fuel can be further reduced. In addition, the adhesion between the layers and the formability become good, and the fuel tank becomes excellent in manufacturability.

The fuel tank according to claim 4 is characterized by further comprising a barrier layer disposed between the foam layer and the welding layer to prevent the permeation of fuel.

  According to the present invention, since the barrier layer is provided, the leakage due to the permeation of the fuel can be well prevented. In addition, since the barrier layer is disposed inside the foam layer, the swelling of the foam layer by the fuel is prevented, and the function of the foam layer and the shielding property of the fuel are maintained for a long time. As a result, it is possible to provide a fuel tank that has low leakage due to fuel permeation, is lightweight, and has high rigidity.

The fuel tank according to claim 5 is characterized by further comprising an outer skin layer disposed on the outer side of the outer side of the fiber reinforced layer to protect the fiber reinforced layer.

  According to the present invention, the outer fiber reinforced layer is well protected against the external force applied from the outside of the fuel tank because the outer layer is provided. Therefore, it is possible to provide a fuel tank having high rigidity while being light in weight, with little reduction in rigidity and appearance of appearance due to external force.

  According to the present invention, it is possible to provide a fuel tank that is lightweight but has high rigidity.

It is a perspective view showing a schematic shape of a fuel tank concerning one embodiment of the present invention. It is a partial expanded sectional view which shows typically the structure of the wall part of the fuel tank which concerns on one Embodiment of this invention. FIG. 1 is a cross-sectional view schematically showing a cross-sectional structure of a fuel tank according to an embodiment of the present invention. It is a figure which shows an example of the welding process of the fuel tank which concerns on one Embodiment of this invention. (A) is a figure which fixed each member to a fixing jig, (b) is a figure which shows the state which is heating each member. It is a figure which shows an example of the welding process of the fuel tank which concerns on one Embodiment of this invention. (A) is a state which welds each member, (b) is a figure which shows the state which is pressurizing the peripheral part of each member. It is a figure which shows the other example of the welding process of the fuel tank which concerns on one Embodiment of this invention.

  Hereinafter, a fuel tank according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, about the structure which is common in each figure, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

FIG. 1 is a perspective view showing a schematic shape of a fuel tank according to an embodiment of the present invention.
A fuel tank 1 shown in FIG. 1 has a hollow fuel tank main body (main body) 2. More specifically, the fuel tank body 2 is formed of an upper member 2A constituting a substantially upper half portion of the main body container and a lower member 2B constituting a substantially lower half portion.

  A fuel pump mounting hole 4, a purge pipe mounting hole 6, and a return pipe mounting hole 8 are provided on the upper surface of the upper member 2A. The fuel pump mounting hole 4 is provided with a cap mounting member 10 so as to protrude outward from the wall portion of the fuel tank main body. A purge pipe connected to the canister is attached to the purge pipe attachment hole 6. Further, a return pipe for returning fuel from the regulator is attached to the return pipe attachment hole 8. Further, on the side surface of the fuel tank body 2, a fuel inlet (not shown) to which a fuel supply pipe is attached is provided. The fuel pump mounting hole 4 and the cap mounting member 10 will be described later.

FIG. 2 is a partially enlarged cross-sectional view schematically showing a structure of a wall portion of a fuel tank according to an embodiment of the present invention.
As shown in FIG. 2, the fuel tank body 2 has a wall portion of a multilayer structure in which each layer is formed of a synthetic resin. Specifically, the wall portion of the fuel tank main body 2 includes a foam layer 20, fiber reinforced layers 21 (21a and 21b), a welding layer 22, a barrier layer 23, and an outer skin layer 24. In the fuel tank main body 2 shown in FIG. 3, as the fiber reinforced layer 21, the first fiber reinforced layer 21 a is disposed inside the foam layer 20, and the second fiber reinforced layer 21 b outside the foam layer 20. Is arranged. Also, the barrier layer 23 constitutes a barrier film 30 multilayered with the adhesive layer 25.

  In each of the upper member 2A and the lower member 2B, the multilayer structure shown in FIG. 2 forms a wall portion of the fuel tank main body 2 in which fuel such as gasoline is stored. Specifically, the respective wall portions of the upper member 2A and the lower member 2B are the first fiber reinforced layer 21a, the welding layer 22, the adhesive layer 25, the barrier, from the inner side facing the inner space of the fuel tank to the outer side. The layer 23, the adhesive layer 25, the foam layer 20, the second fiber reinforced layer 21b, and the outer layer 24 are laminated in this order.

  The foam layer 20 is formed of a foam resin. The foam layer 20 has numerous cells in the layer, and is a layer having the largest thickness among the plurality of layers constituting the multilayer structure. The weight per layer of the foam layer 20 can be adjusted while securing the rigidity by appropriately changing the layer thickness and the cell ratio. Therefore, by providing the foam layer 20, the fuel tank main body 2 can reduce the fabric weight while having a certain rigidity or more.

  Specifically as a material which forms foaming layer 20, foaming polypropylene, foaming polyethylene (foaming high density polyethylene etc.), foaming polyamide, foaming polyester, etc. can be used. A particularly preferred material among these is foamed polypropylene. Foamed polypropylene is excellent in oil resistance and strength, and excellent in accuracy of shape and dimension at the time of molding.

  The foaming layer 20 may be foamed by dissolving a gas at the time of formation of the layer, or may be foamed by adding a foaming agent. However, from the viewpoint of enhancing the rigidity of the foam layer 20 and the shielding property of the fuel, it is preferable to foam by adding a foaming agent. According to the foaming agent, the formation of closed cells and the uniformity of the foaming rate can be easily ensured, so that excessive reduction in rigidity and permeation of fuel can be avoided.

  As a gas to be dissolved for foaming, for example, a suitable gas such as nitrogen gas, carbon dioxide gas, hydrocarbon gas such as butane, pentane or hexane, or halogenated hydrocarbon substituted with fluorine or the like may be used. Can. Moreover, as a foaming agent, any of an inorganic type foaming agent and an organic type foaming agent can also be used. Examples of the inorganic foaming agent include carbonates such as ammonium carbonate and calcium carbonate, hydrogencarbonates such as sodium hydrogencarbonate, and organic acid salts such as sodium citrate. Moreover, as an organic type foaming agent, azodicarbonamide, dinitroso pentamethylene tetramine, azoisobutyrodinitrile etc. are mentioned, for example.

  Although the thickness of the foam layer 20 depends on the specification of the fuel tank body 2 and the degree of porosity, it may be provided in the range of about 3 mm to 5 mm, about 4 mm, as an example.

  The fiber reinforced layer 21 (21a, 21b) is formed of a fiber reinforced resin. In detail, the fiber reinforced layer 21 (21 a, 21 b) has a matrix 121 made of a synthetic resin and reinforcing fibers 122 embedded in the matrix 121. Even when the fiber reinforced layer 21 (21a, 21b) is thinned, the reinforcing fiber 122 having high strength and hardness maintains high rigidity. Therefore, the fuel tank main body 2 is provided with the fiber reinforced layer 21 (21a, 21b), so that high rigidity can be provided while supporting weight reduction.

  As the matrix phase 121, for example, an appropriate thermoplastic resin such as polypropylene, polyethylene (such as high density polyethylene), polyester, polyamide, or polyester can be used. Particularly preferable material among them is polyethylene, and high density polyethylene is particularly preferably used. Polyethylene has a relatively low melting point, and welding of the upper member 2A and the lower member 2B of the fuel tank body 2, adhesion between the fiber reinforced layer 21 (21a, 21b) and the adjacent layer, or below the melting point of the reinforcing fiber 122 It is because it is suitable for molding and the like. The matrix phase 121 may be formed using thermoplastic organic fibers as the reinforcing fibers 122 and melting the reinforcing fibers 122 at the time of welding.

  Examples of the reinforcing fibers 122 include inorganic fibers such as glass fibers, carbon fibers, ceramic fibers, and mineral fibers, and organic fibers such as polypropylene fibers, polyethylene fibers, polyester fibers, aramid fibers, acrylic fibers, polyamide fibers, and polyester fibers. It can be used. Particularly preferred materials among these are polypropylene fibers. The polypropylene fiber has good oil resistance and strength, is lightweight, has high flexibility, and has thermoplasticity which contributes to welding of the upper member 2A and the lower member 2B of the fuel tank body 2.

  The reinforcing fibers 122 may be in any form such as a woven fabric, a non-woven fabric, or a molded body. Although a dry method, a wet method, etc. can be used as a formation method of the nonwoven fabric-like reinforcement fiber 122, It is preferable to use a spun bond method from a viewpoint of raising rigidity. Further, as the reinforcing fiber 122 in the form of a molded body, a fiber obtained by forming fibers aligned in a uniaxial direction or a multiaxial direction into an appropriate shape can be used. However, from the viewpoint of securing high rigidity of the fuel tank main body 2, it is preferable that the reinforcing fiber 122 be in a woven form. The reinforcing fiber 122 may contain in advance a flame retardant such as antimonys, halides, phosphoric esters, borates, magnesium hydroxide, aluminum hydroxide and the like.

  The thickness of the fiber reinforced layer 21 (21a, 21b) depends on the specification of the fuel tank body 2. As an example, the thickness of the fiber reinforced layer 21 (21a, 21b) is about 0.3 mm or more and 0.7 mm or less. , 5% or more and 15% or less.

  The welding layer 22 is formed of a thermoplastic resin. The welding layer 22 is disposed between the foam layer 20 and the first fiber reinforced layer 21a, specifically, between the barrier film 30 and the first fiber reinforced layer 21a. The multi-layered structure shown in FIG. 2 includes a foam layer 20 having air bubbles and capable of reducing the weight per layer and a reinforcing fiber 122 which is not completely melted at the time of welding, and the thickness is A first fiber reinforced layer 21a that can be held thin is provided. Therefore, there is a possibility that good joint strength can not be obtained in joining by welding between the upper member 2A and the lower member 2B having this multilayer structure or by welding between these and other members. The welding layer 22 functions as a welding margin for assuring the bondability by such welding.

  Specifically, polypropylene, polyethylene (high density polyethylene etc.), polyamide, polyester etc. can be used as a material which forms welding layer 22. Particularly preferable material among them is polyethylene, and high density polyethylene is particularly preferably used. Polyethylene has a relatively low melting point and is suitable for welding between the upper member 2A and the lower member 2B of the fuel tank body 2 and adhesion between the welding layer 22 and the adjacent layer.

  Although the thickness of the welding layer 22 depends on the specification of the fuel tank main body 2, as an example, it may be provided in a range of about 0.5 mm or more and 2.0 mm or less, about 1 mm.

  The barrier film 30 is formed of the barrier layer 23 and the adhesive layers 25 and 25 laminated on the both surfaces thereof, and is disposed between the foam layer 20 and the welding layer 22. The barrier layer 23 is provided to prevent permeation of the fuel stored in the internal space of the fuel tank main body 2 and the fuel gas generated by the vaporization of the fuel. The adhesive layer 25 bonds the barrier film 30 (barrier layer 23) to the adjacent layer.

  Specifically, suitable materials for forming the barrier layer 23 include synthetic resins such as ethylene vinyl alcohol copolymer, polyvinyl alcohol and polyacrylonitrile, and composite materials of synthetic resin and inorganic material or metal material. Can be used. Particularly preferred materials among these are ethylene vinyl alcohol copolymers. The ethylene-vinyl alcohol copolymer has good oil resistance and gas barrier properties, and exhibits melt-moldable thermoplasticity. Moreover, it is because it is suitable for adhesion | attachment with the resin of an olefin type.

  Specifically, a material such as a modified polyolefin resin, for example, an unsaturated carboxylic acid-modified polyethylene resin or a low density polyethylene can be used as a material for forming the adhesive layer 25. Particularly preferred materials among these are unsaturated carboxylic acid modified polyethylene resins. The unsaturated carboxylic acid-modified polyethylene resin is suitably used for multilayer extrusion molding, and it is because the layer shape of the barrier layer 25 can be maintained and the gas barrier property can be surely exhibited. Moreover, it is because it is suitable for adhesion | attachment with the resin of an olefin type.

  Although the thickness of the barrier film 30 depends on the gas permeability and the like of the material forming the barrier layer 20, the thickness may be, for example, about 0.1 mm. In addition, although the barrier film 30 is made into the form which consists of the barrier layer 23 and the adhesive bond layer 25 in FIG. 1, the form by which the layer of the thermoplastic resin was laminated further outside the adhesive bond layer 25 etc. It may be in a form having a layer structure of

  The outer covering layer 24 is disposed on the further outside of the second fiber reinforced layer 21 b and forms the outer covering of the fuel tank main body 2. The outer covering layer 24 protects the reinforcing fibers 122 included in the second fiber reinforced layer 21 b from external force and the like by being provided further outside the second fiber reinforced layer 21 b disposed outside. That is, even when the fuel tank main body 2 receives pressure, frictional force, etc. from the vehicle body frame or a support member supported on the vehicle body side, the reinforcing fiber 122 is exposed from the matrix phase 121 or the reinforcing fiber 122 is frayed. Is to be prevented. Therefore, the rigidity exhibited by the reinforcing fiber 122 is easily maintained in the fuel tank main body 2, and the designability of the appearance is hardly impaired.

  As the outer cover layer 24, for example, an appropriate resin such as polypropylene, polyethylene (such as high density polyethylene), polyester, polyamide, or polyester can be used. An especially preferred material among these is polypropylene. Polypropylene has good oil resistance and strength, and also has good moldability and smoothness.

  Although the thickness of the outer covering layer 24 depends on the specification of the fuel tank body 2, as an example, the thickness of the outer layer 24 is in the range of about 0.03 mm or more and 0.07 mm or less, and 0.5% or more with respect to the total thickness of the wall portion It may be provided at about 1.5% or less.

  Next, the structure of the fuel tank according to the present embodiment will be described.

FIG. 3 is a cross-sectional view schematically showing a cross-sectional structure of a fuel tank according to an embodiment of the present invention. In FIG. 3, the multilayer structure (see FIG. 2) of the wall portion of the fuel tank body 2 is shown in a simplified manner, and various equipment parts to be instrumented in the fuel tank body 2 are omitted.
As shown in FIG. 3, the fuel tank main body 2 is formed of an upper member 2A and a lower member 2B which are respectively formed in a concave shape. The concave upper member 2A and the lower member 2B constitute a substantially upper half and a lower half of the container shape of the fuel tank 1, respectively.

  The upper member 2A has a flat welding portion 114a on the outer edge side of the concavely formed region. Further, the lower member 2B similarly has a flat welding portion 114b on the outer edge side of the concavely formed region. By welding the welded portion 114a and the welded portion 114b, the upper member 2A and the lower member 2B are joined to each other, and the fuel tank main body 2 is formed.

  The welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B have a multilayer structure in which the welded layer 22 is provided under the first fiber reinforced layer 21a as shown in FIG. ing. Therefore, the upper member 2A and the lower member 2B are joined with high bonding strength by mainly melting and integrating the synthetic resin that constitutes the first fiber reinforced layer 21a and the welding layer 22 that functions as a welding margin. Be done. In the fuel tank 1 according to the present embodiment, such welding with high bonding strength prevents separation of the bonding portion and leakage of fuel through the bonding portion.

  In addition, the upper member 2A has a side end portion 116a crushed in the thickness direction at the side end of the flat welding portion 114a. Further, the lower member 2B similarly has a side end 116b crushed in the thickness direction at the side end of the flat welding portion 114b. The side end 116 a and the side end 116 b are crushed and densified to enhance the shielding of the gas.

  The welded portion 114a and the welded portion 114b, as shown in FIG. 2, are provided with the foam layer 20 having air bubbles, and the barrier layer 23 is not interposed in the direction along the layer of the foam layer 20, and the shielding property is low. It has become. Therefore, the side end portion 116a and the side end portion 116b having high gas shielding properties are provided to enhance the shielding properties of the gas passing through the joint. In the fuel tank 1 according to the present embodiment, with such a structure, it is possible to prevent the fuel from leaking through the joint.

  On the other hand, a fuel pump mounting hole 4 is provided through the top of the upper member 2A. The fuel pump mounting hole 4 is joined with a cap mounting member 10 separate from the upper member 2A. The cap attachment member 10 is a member to be fastened with a fuel pump module (not shown). The cap mounting member 10 is integrally formed of a synthetic resin, and has a cylindrical portion 102 provided with a screw groove on the side, and a flange portion 104 extending laterally from the lower edge of the cylindrical portion 102. And. A fuel pump module (not shown) is inserted into the fuel pump mounting hole 4 and mounted inside the fuel tank body 2. At this time, the lid portion provided on the upper side of the fuel pump module is fixed by a nut-type cap screwed into the screw groove of the cap mounting member 10, whereby the fuel pump mounting hole 4 is sealed.

  Generally, the fuel tank body is often manufactured by blow molding, and the cap mounting portion provided on the upper side of the fuel pump module is also integrally molded so as to protrude outward from the wall portion of the fuel tank body. There are many. When the cap mounting portion is integrally molded by blow molding in this manner, it is often the case that a thin region locally occurs in the vicinity of the cap mounting portion having a complicated shape.

  On the other hand, in the fuel tank 1 according to the present embodiment, as shown in FIG. 3, the cap mounting member 10 is provided separately from the fuel tank main body 2 (upper member 2A). Since the separate cap attachment member 10 can be manufactured by die molding instead of blow molding, the accuracy of the shape and dimension can be increased, and rigidity is enhanced. In addition, since it is possible to manufacture a material different from the fuel tank main body 2 if it is a material having good weldability by welding, it is also possible to provide it with higher rigidity. Therefore, in the fuel tank 1 according to the present embodiment, when the fuel tank main body receives an impact or receives a load due to a swing of the fuel pump module by being provided with the separate cap attachment member 10 In addition, the vicinity of the fuel pump mounting hole 4 is less likely to become a starting point of destruction, and the improvement of impact resistance is achieved.

  Further, in the fuel tank 1 according to the present embodiment, the separate cap attachment member 10 is joined by welding the upper surface of the flange portion 104 and the top lower surface 112 of the upper member 2A to each other. That is, the cap attachment member 10 is joined to the inside of the fuel tank main body 2. According to such a structure, the fuel pump module can be reliably secured by sandwiching the peripheral portion of the fuel pump mounting hole 4 of the upper member 2A with the cap screwed to the cap mounting member 10 and the flange portion 104 of the cap mounting member 10. Support it. In addition, the sealing performance of the fuel pump mounting hole 4 can be improved. Therefore, in the fuel tank 1 according to the present embodiment, the fuel sealability can be improved in addition to the impact resistance in the vicinity of the fuel pump mounting hole 4.

  Next, a method of manufacturing the fuel tank according to the present embodiment will be described.

  In the fuel tank 1 according to the present embodiment, the upper member 2A and the lower member 2B each have a fiber reinforced layer 21 (21a, 21b), and the reinforcing fiber 122 secures the rigidity (see FIG. 2). Therefore, unlike the blow molding, twin sheet blow molding, etc., the method of manufacturing the fuel tank main body 2 is a method in which the orientation and sewn state of the reinforcing fibers 122 constituting the fiber reinforced layer 21 (21a, 21b) are not easily impaired. It is suitable.

  The fuel tank main body 2 can be manufactured by forming the sheet-formed upper member 2A and lower member 2B into a container shape and bonding them together. For example, a method in which the upper member 2A and the lower member 2B are respectively press-formed and joined together by welding, or a method in which the upper member 2A and the lower member 2B are simultaneously formed by vacuum forming and pressure forming and joined together by welding (Twin Composite molding methods can be used.

  As a material of the upper member 2A and the lower member 2B, a sheet in which each layer of the multilayer structure shown in FIG. 2 is previously laminated may be used for forming, or a plurality of sheets corresponding to each layer may be overlapped and formed. You may use. For example, in the case of using a plurality of sheet bodies corresponding to each layer, the respective sheet bodies may be stacked and subjected to heat press forming to form a single sheet body, and this sheet body may be used as a material for forming.

  As a method of welding the upper member 2A and the lower member 2B, various methods such as hot plate welding, injection welding, high frequency welding, ultrasonic welding, laser welding and the like can be used. In the following, as an example of a method of manufacturing the fuel tank main body 2, a method of joining the upper member 2A and the lower member 2B which are formed in advance into a container shape by hot plate welding will be described.

FIG. 4 is a view showing an example of a welding process of a fuel tank according to an embodiment of the present invention. Fig.4 (a) is a figure which shows the state which fixed each member to the fixing jig, and FIG.4 (b) shows the state which is heating each member.
As shown in FIG. 4A, when joining the upper member 2A and the lower member 2B by welding, the upper member 2A and the lower member 2B are respectively divided into the first fixing jig 210A and the second fixing jig 210B. Fix it.

  The first fixing jig 210A and the second fixing jig 210B have recesses capable of surface-supporting the upper member 2A and the lower member 2B from the outside, and are provided movable by a movable mechanism (not shown). For example, the first fixing jig 210 </ b> A and the second fixing jig 210 </ b> B can be moved relative to each other stepwise from the separated state to the closely pressed state.

  Further, in association with the first fixing jig 210A and the second fixing jig 210B, a first pressure forming mold 212A, a second pressure forming mold 212B, and a heat plate 250 are provided. The first pressure molding die 212A and the second pressure molding die 212B are provided along the outer circumferences of the first fixing jig 210A and the second fixing jig 210B, and the upper member 2A and the lower member 2B are provided. It is provided to press mold the outer edge of the. On the other hand, the heat plate 250 is provided so as to be movable back and forth between the first fixing jig 210A and the second fixing jig 210B.

  The upper member 2A and the lower member 2B are fixed in advance to the first fixing jig 210A and the second fixing jig 210B in a state of being press-formed into the container shape of each half of the fuel tank 1. At this time, in the upper member 2A and the lower member 2B, the first fiber reinforced layer 21a, the welding layer 22, the barrier film 30, the foam layer 20, the second fiber reinforced layer 21b and the outer layer 24 are laminated in this order in advance. is there. Such upper member 2A and lower member 2B are prepared by subjecting a sheet having a multilayer structure to press forming or the like according to the shape of the container. As shown to Fig.4 (a), it is possible to weld the cap attachment member 10 to 2 A of upper members beforehand.

  Subsequently, as shown in FIG. 4B, the heat plate 250 is inserted between the upper member 2A and the lower member 2B, and the first fixing jig 210A and the second fixing jig 210B are brought close to each other. The upper member 2A and the lower member 2B are in close contact with the heat plate 250. The welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B are heated by being pressed by the heated heat plate 250. At this time, on the welding surface A located inside the welding portion 114a and the welding portion 114b, the synthetic resin constituting the first fiber reinforced layer 21a and the welding layer 22 functioning as a welding margin mainly melt. The heating temperature, the heating time, and the pressing pressure may be appropriately set in consideration of the melting point of the welding layer 22, the bonding strength, and the like.

  FIG. 5 is a view showing an example of a process before welding of a fuel tank according to an embodiment of the present invention. Fig.5 (a) is a state which welds each member, FIG.5 (b) is a figure which shows the state which is pressurizing the peripheral part of each member.

  After heating the welding surface A of the upper member 2A and the lower member 2B and withdrawing the heat plate 250, as shown in FIG. 5A, the welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B Butt and press each other. By pressing the welding surface A in this manner, the welding portion 114a and the welding portion 114b are partially integrated. The pressing time and the pressing pressure may be appropriately set in consideration of bonding strength and the like. At this time, the first pressure molding die 212A and the second pressure molding die 212B are not in close contact with each other, and are stopped at separated positions.

  Subsequently, as shown in FIG. 5B, while the upper member 2A and the lower member 2B are fixed, the first pressure molding die 212A and the second pressure molding die 212B are pressed against each other, The outer edge (side end 116a) of the welded portion 114a of the upper member 2A and the outer edge (side end 116b) of the welded portion 114b of the lower member 2B are further pressed. Then, the welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B are cooled while being maintained in a pressurized state. The welded portion 114a and the welded portion 114b are completely cooled before being pressed by the first pressure molding die 212A and the second pressure molding die 212B, and the first pressure molding die 212A and the second pressure molding die Press forming may be performed by heat pressing according to 212B, or semi-cooling may be performed to maintain appropriate fluidity, and press forming of the outer edge may be performed in a semi-molten state.

  The welded portion 114a and the welded portion 114b are joined by cooling the welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B which are partially integrated by heating. Further, the respective outer edges of the welded portion 114a and the welded portion 114b are pressure-formed into a thin flat shape by the first pressure-molding die 212A and the second pressure-molding die 212B. That is, at the outer edge of the upper member 2A and the lower member 2B, the side end portion 116a and the side end portion 116b which are crushed in the thickness direction are formed.

  According to the above manufacturing method of the fuel tank 1 (fuel tank main body 2), since the upper member 2A and the lower member 2B which are sheeted in advance by press molding are used, the cap mounting member is provided on the inside of the fuel tank main body 2. 10 can be easily joined. On the other hand, in general blow molding, such bonding to the inner side is difficult, and the orientation and the sewing state of the reinforcing fibers 122 are easily impaired. Moreover, in general twin sheet blow molding, the equipment cost etc. for joining to the inner side increase, and positioning of a joining position is not easy, either. That is, this manufacturing method using a material provided with the welding layer 22 and having a good bonding property by welding is advantageous for the manufacture of the fuel tank 1 having improved impact resistance and fuel sealing property.

  Further, according to the method of manufacturing fuel tank 1 (fuel tank main body 2) described above, since hot plate welding is adopted for joining upper member 2A and lower member 2B, joining between upper member 2A and lower member 2B The strength of the part can be improved. In the welded portion 114a and the welded portion 114b, the welded layer 22 provided under the first fiber reinforced layer 21a is thermally transferred from the heat plate 250 through the first fiber reinforced layer 21a which may be provided thin. It melt | melts with uniformity and it can exhibit the function as a welding margin appropriately.

  Next, another example of the method of manufacturing the fuel tank according to the present embodiment will be described.

  In the manufacture of the fuel tank body 2, it is also possible to join the upper member 2A and the lower member 2B by injection welding. For example, as shown in FIG. 5A, in a state where the welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B are butted, a joint portion (welded portion 114a) of the upper member 2A and the lower member 2B. And it is possible to perform injection welding from the side of welding part 114b). The welded portion 114a and the welded portion 114b may be heated by the heat plate (250) before reaching this state, but may not be heated in advance.

FIG. 6 is a view showing another example of the fuel tank welding process according to the embodiment of the present invention. FIG. 6 (a) is an enlarged cross-sectional view schematically showing the vicinity of a bonding portion of each member clamped to the injection molding die, and FIG. 6 (b) is a bonding portion of each member formed secondarily It is sectional drawing which shows schematic shape typically.
As shown in FIG. 6A, in this welding step, injection welding is performed using the first injection molding die 214A and the second injection molding die 214B together with the first fixing jig 210A and the second fixing jig 210B. Do. While the upper member 2A and the lower member 2B are joined by injection welding, a sealing portion 130 is formed on the side of the joined portion (welded portion 114a and the welded portion 114b) between the upper member 2A and the lower member 2B (FIG. b) see (2).

  The first injection molding die 214A and the second injection molding die 214B are replaced with the first pressure molding die 212A and the second pressure molding die 212B (see FIGS. 4 and 5), and the first fixing jig 210A and the second injection molding die 214B are used. It is provided along the outer periphery of each of the two fixing jigs 210B. The first injection molding die 214A and the second injection molding die 214B each have a recess 231a and a recess 231b, as shown in FIG. 6 (a). The recessed portion 231a and the recessed portion 231b are respectively formed by the welded portion 114a of the upper member 2A fixed to the first fixing jig 210A and the welded portion 114b of the lower member 2B fixed to the second fixing jig 210B. It is provided in the position which can be protruded.

  In the first injection molding die 214A and the second injection molding die 214B, the first fixing jig 210A and the second fixing jig 210B are pressed against each other, and the welding portion of the upper member 2A and the welding portion of the lower member 2B. It is provided so that it may be clamped in the state which abuts and is pressurized. And in the state where mold clamping was carried out, cavity 233 is formed of crevice 231a and crevice 231b. The cavity 233 is formed so as to include the side end of the welded portion 114a of the upper member 2A and the side end of the welded portion 114b of the lower member 2B over the entire circumference.

  As shown in FIG. 6A, the second injection molding die 214B is provided with an injection hole 234 communicating with the cavity 233. A nozzle of an extrusion kneader (not shown) is connected to the injection hole 234. A plurality of injection holes 234 may be provided along the entire circumference of the upper member 2A and the lower member 2B, or may be provided slidably along the circumferential direction. The injection holes 234 may be provided in the first injection mold 214A, or may be provided in both the first injection mold 214A and the second injection mold 214B.

  In the injection molding, a thermoplastic resin melt-kneaded is injected from an extrusion kneader connected to the injection hole 234. As a material to be injected, for example, polypropylene, polyethylene (high density polyethylene etc.), polyamide, polyester etc. can be used. The injected high temperature thermoplastic resin fills the cavity 233 and partially melts the welded portion 114a and the welded portion 114b. Therefore, after cooling, as shown in FIG. 6B, the welded portion 114a of the upper member 2A and the welded portion 114b of the lower member 2B are joined, and the welded portion 114a and the welded portion 114b are sealed The stop 130 is injection molded.

  According to the method of manufacturing the fuel tank 1 (the fuel tank main body 2) described above, the sealing portion 130 is formed so as to cover the welding portion 114a and the side ends of the welding portion 114b over the entire circumference. Therefore, the sealing portion 130 reliably seals the side edge in the longitudinal direction of the multilayer structure of the upper member 2A and the lower member 2B, and the gap that can be generated at the contact surface of the welded portion 114a and the welded portion 114b. . Therefore, it is possible to more reliably prevent leakage of fuel that may occur due to failure of welding, side leakage along the direction of the stratum that can not be prevented by the barrier layer 20 in the multilayer structure, and the like.

  Note that various changes can be made to the configuration of the fuel tank 1 (the fuel tank main body 2) and the method of manufacturing the same without changing the gist of the invention. For example, the fuel tank main body 2 can be provided in an appropriate shape, and the position of the welding surface A is not limited only to the outer edge side. In addition to the first fiber reinforced layer 21a, the welding layer 22, the barrier film 30, the foam layer 20, the second fiber reinforced layer 21b, and the outer coat layer 24, the fuel tank main body 2 may have other layers. . Also, instead of the barrier film 30, a single layer or multiple layers with low gas permeability may be formed. In addition, the fiber reinforcing layer 21 and the foam layer 20 may be alternately multi-layered on the outside of the welding layer 22. About the apparatus used for manufacture of the fuel tank 1, it is possible to set it as a suitable structure and shape.

DESCRIPTION OF SYMBOLS 1 fuel tank 2 fuel tank main body 2A upper member 2B lower member 4 fuel pump attachment hole 6 purge pipe attachment hole 8 return pipe attachment hole 10 cap attachment member 20 foam layer 21a first fiber reinforced layer 21b second fiber reinforced layer 22 welded layer 23 barrier layer 24 outer skin layer 25 adhesive layer 30 barrier film 102 tubular portion 104 flange portion 112 top lower surface 114a, 114b welded portion 116a, 116b side end portion 121 matrix 122 reinforcing phase 130 reinforcing fiber 130 sealing portion 210A first fixing jig 210B second fixing jig 212A first pressure molding die 212B second pressure molding die 214A first injection molding die 214B second injection molding die 231a, 231b recessed portion 233 cavity 234 injection hole 250 heat plate

Claims (5)

A fuel tank having a multilayer structure formed of a synthetic resin, wherein
A foam layer formed of a foam resin,
A fiber reinforced layer formed of a fiber reinforced resin and disposed on the inner side and the outer side of the foam layer, respectively;
And a welding layer formed of a thermoplastic resin and disposed between the foam layer and the inner fiber reinforced layer .
A fuel tank characterized in that the fiber reinforced layer comprises organic fibers embedded in a matrix . The fuel tank according to claim 1, wherein the fiber reinforcing layer is formed of polypropylene fibers and a matrix of polyethylene. The foam layer is formed of foamed polypropylene,
The fiber reinforced layer is formed of polypropylene fibers and a matrix of polyethylene,
The welding layer is, the fuel tank according to claim 1 or claim 2, characterized in that it is formed by polyethylene. The fuel tank according to any one of claims 1 to 3, further comprising a barrier layer disposed between the foam layer and the welding layer to prevent fuel permeation. The fuel tank according to any one of claims 1 to 4 , further comprising an outer skin layer disposed further outside the outer side of the fiber reinforced layer to protect the fiber reinforced layer.

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