JP2006160093A - Fuel tank for automobile and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fuel tank for automobiles and a method for manufacturing the same, in which when an upper tank and a lower tank are formed separately, the joint has a high fuel permeation preventing property and sufficient rigidity.
SOLUTION: In an automobile fuel tank 1 formed of an inner surface resin layer 10 and an outer surface resin layer 20 made of a thermoplastic synthetic resin, the inner surface resin layer 10 is divided into an upper tank portion 11 and a lower tank portion 16 separately. A fuel for automobiles which is formed by molding and joining the peripheral edges of the respective openings, and the outer resin layer 20 is integrally formed so as to cover the entire outer periphery of the joined inner resin layer 10. A tank and its manufacturing method.
[Selection] Figure 2

Description

  The present invention relates to an automotive fuel tank made of a thermoplastic synthetic resin and formed from an inner surface resin layer and an outer surface resin layer, and a method for manufacturing the same.

Conventionally, the structure of a fuel tank for automobiles has been made of metal. However, in recent years, thermoplastic synthetic resins have been used due to the weight reduction of vehicles, the absence of rust, and the ease of molding into desired shapes. The ones made by the company have come to be used.
For the production of automobile fuel tanks made of synthetic resin, blow molding methods have been often used because of the ease of molding hollow bodies. In the blow molding method, a melted synthetic resin parison is formed into a cylindrical shape and extruded from above, and the parison is sandwiched between molds and air is blown into the parison to manufacture an automobile fuel tank.

However, this method increases the overall weight of the parison in the case of a large synthetic resin hollow product such as an automobile fuel tank, and increases the strength when the strength of the automobile fuel tank is required. Therefore, the weight of the parison also increases when manufacturing a thick automotive fuel tank, and when the molten parison is dropped from the upper part of the molding machine into the mold, the upper wall thickness is lower. In some cases, it was thinner than the wall thickness.
In addition, in the case of a product with a complicated shape such as a fuel tank for automobiles, when the parison is expanded in the mold, the rate of expansion of the parison may vary depending on the part of the product. In some cases, there was variation.

In a blow molded automobile fuel tank, it is difficult to provide ribs, beams and the like, and the rate of expansion of the parison may vary depending on the part of the product, resulting in variations in the wall thickness of the tank. Therefore, a great deal of labor has been required for wall thickness management and quality control. Furthermore, it is difficult to attach accessories such as valves in the fuel tank.
Therefore, the synthetic resin hollow body is divided into upper and lower parts, molded separately by injection molding or the like, and then the upper tank and the lower tank are abutted at the abutting portion to form a fuel tank.

  In such a method of forming the upper tank and the lower tank, for example, a sheet-like laminate comprising an inner surface material, a permeation prevention film and an outer surface material is press-molded to form an upper and lower divided body, and then the upper and lower divided bodies are formed. There is one that welds and joins bodies (for example, see Patent Document 1). However, when this sheet-like laminate is press-molded, if the thickness of the laminate is increased, molding becomes difficult, and it is difficult to produce a tank having sufficient strength.

  Further, there is a type in which an upper tank and a lower tank are respectively formed to form an inner layer and an outer layer, and a fuel impervious layer is sandwiched between the inner layer and the outer layer to join the upper tank and the lower tank. (For example, refer to Patent Document 2). However, in the manufacturing method as described above, it is necessary to individually mold the upper tank and the lower tank forming the inner layer and the outer layer, and it is also necessary to shape the fuel impervious layer into a tank shape. It was.

Furthermore, a method has also been proposed in which a laminate of a permeation prevention film and an outer material is formed into a shape close to a finished product, and then the inner material melted is compression molded (see, for example, Patent Document 3). In this case, if the thickness of the laminate is increased, it is difficult to form a laminate of the permeation prevention film and the outer material into a shape close to the finished product, and it is also difficult to form protrusions or the like on the outer surface. there were.
And when such an upper tank and a lower tank are formed separately and the peripheral edge of the opening is welded, in order to increase the reliability of the welded portion, the non-welded between the resin layer of the tank body and the permeation prevention film A tape is also proposed (for example, see Patent Document 4).
Japanese Patent Application Laid-Open No. H5-16938 JP 2000-280763 A JP-A-5-104552 Japanese Patent Laid-Open No. 11-221858

  Thus, when the upper tank and the lower tank are formed separately, there is a demand for a fuel tank for automobiles and a method for producing the same, which has high rigidity for preventing fuel permeation at the joint, has sufficient rigidity, is easy to manufacture, and has excellent quality. It was done.

The present invention of claim 1 for solving the above-mentioned problem is a fuel tank for automobiles formed of an inner surface resin layer and an outer surface resin layer made of thermoplastic synthetic resin.
The inner surface resin layer is formed by combining the opening peripheral portions of the upper tank portion and the lower tank portion separately formed separately, and the outer surface resin layer covers the entire outer periphery of the bonded inner surface resin layer. An automobile fuel tank characterized by being integrally formed.

  In the first aspect of the present invention, the automobile fuel tank is formed of a thermoplastic synthetic resin inner surface resin layer and an outer surface resin layer. For this reason, resin excellent in fuel permeation prevention property can be used for the inner surface resin layer. Or the sheet | seat etc. which were excellent in fuel permeation prevention property can be provided between an inner surface resin layer and an outer surface resin layer. For the outer resin layer, a highly rigid resin capable of ensuring the strength of the fuel tank can be used, and there is a large room for material selection.

  The inner surface resin layer is formed by combining the opening peripheral portions of the upper tank portion and the lower tank portion which are separately divided and molded. For this reason, an upper tank part and a lower tank part can be shape | molded separately, and each can be shape | molded by injection molding, and a dimensional accuracy and a strong upper tank part and a lower tank part can be obtained. Therefore, a synthetic resin fuel tank formed by combining the upper tank portion and the lower tank portion can provide a precise and high strength product with high dimensional accuracy. Further, it is possible to easily attach a reinforcing rib, a built-in component, or the like inside the upper tank portion and the lower tank portion.

  The outer resin layer is integrally formed so as to cover the entire outer periphery of the bonded inner resin layer. For this reason, unlike the inner surface resin layer, the outer surface resin layer has no joint portion and is formed integrally as a whole. Therefore, the strength of the joint portion of the inner surface resin layer can be ensured. Furthermore, since the resin having excellent fuel permeation prevention properties are joined to each other at the joining portion of the inner surface resin layer and there is no gap, it is possible to prevent the permeation of fuel from the joining portion of the inner surface resin layer.

  Furthermore, a protrusion is integrally formed from the inner surface resin layer toward the inside of the tank, and a protrusion is integrally formed from the outer surface resin layer toward the outside of the tank. For this reason, it is possible to form inner and outer ribs for improving the strength of the fuel tank, and to provide protrusions for attaching parts such as valves inside the tank and parts such as hoses outside the tank. Can be easily installed. Further, when the outer resin layer is formed, it can be integrally formed on the outer peripheral front surface of the inner resin layer, so that the inner resin layer and the outer resin layer can be firmly fixed.

  According to a second aspect of the present invention, the inner surface resin layer is formed from a thermoplastic resin having fuel permeation preventing performance, and the outer surface resin layer is a fuel tank for automobiles formed from a thermoplastic resin having rigidity.

  In the present invention of claim 2, since the inner surface resin layer is formed from a thermoplastic resin having fuel permeation preventing performance and the outer surface resin layer is formed from a thermoplastic resin having rigidity, the inner surface resin layer and the outer surface resin layer are used. The strength of the outer wall of the tank can be increased and it will not be damaged even if an external impact is applied. In addition, by covering the inner resin layer for preventing fuel permeation with the outer resin layer, the fuel permeation preventing performance can be ensured even if the inner resin layer is thinned.

  In the third aspect of the present invention, the outer resin layer is formed of high density polyethylene (HDPE), and the inner resin layer is made of ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, polyphenylene. It is a fuel tank for automobiles formed from at least one material of sulfite.

In the present invention of claim 3, the outer surface resin layer is formed of high density polyethylene (HDPE). For this reason, the strength is high, the tank wall need not be thick, and the weight of the fuel tank can be reduced. Moreover, since it is excellent in weather resistance, the strength can be maintained for a long time. Furthermore, it is an olefinic thermoplastic synthetic resin and can be easily recycled.
The inner surface resin layer is formed of a material including a layer made of at least one material selected from ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfite. For this reason, it is excellent in fuel permeation prevention property and can prevent permeation of fuel from the fuel tank.

  According to a fourth aspect of the present invention, the inner surface resin layer includes a tank side resin layer formed of a thermoplastic synthetic resin having rigidity inside the upper tank portion and the lower tank portion, and fuel permeation prevention outside the tank side resin layer. This is an automobile fuel tank in which an outer seat for the vehicle is integrally formed.

  According to a fourth aspect of the present invention, the inner surface resin layer includes a tank side resin layer formed of a thermoplastic synthetic resin having rigidity inside the upper tank portion and the lower tank portion, and fuel permeation prevention outside the tank side resin layer. The outer sheet for the is integrally formed. Therefore, the outer sheet can be sandwiched between the tank side resin layer and the outer surface resin layer, and the strength of the tank outer wall can be increased by the three layers of the tank side resin layer, the outer sheet and the outer surface resin layer. Even if an impact is applied, it will not be damaged. Further, by covering the outer sheet for preventing fuel permeation with the inner surface resin layer and the outer surface resin layer, the multilayer sheet can be prevented from being torn and the fuel permeation preventing performance can be secured.

  In the present invention of claim 5, the tank side resin layer and the outer surface resin layer of the inner surface resin layer are formed of high density polyethylene (HDPE), and the outer sheet is made of ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, A fuel tank for automobiles which is a multilayer sheet including a layer made of at least one material selected from polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfite.

According to the fifth aspect of the present invention, since the tank side resin layer and the outer surface resin layer of the inner surface resin layer are made of high density polyethylene (HDPE), the strength is high and the tank wall need not be thick. The weight of the tank can be reduced. Moreover, since it is excellent in weather resistance, the strength can be maintained for a long time. Furthermore, it is an olefinic thermoplastic synthetic resin and can be easily recycled.
The outer sheet is a multilayer sheet including a layer made of at least one material selected from ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfite. For this reason, it is excellent in fuel permeation prevention property and can prevent permeation of fuel from the fuel tank. In addition, since it is a multilayer sheet, it is possible to provide a layer excellent in the bondability between the tank side resin layer and the outer surface resin layer above and below the layer excellent in fuel permeation prevention. Can be reliably joined.

  The present invention of claim 6 is for automobiles in which protrusions are integrally formed from the inner surface resin layer toward the inside of the tank, respectively, and protrusions are integrally formed from the outer surface resin layer toward the tank outward direction. It is a fuel tank.

  According to the sixth aspect of the present invention, protrusions are integrally formed from the upper tank portion and the lower tank portion of the inner resin layer toward the inside of the tank, and the protrusions are integrally formed from the outer surface resin layer toward the tank outward direction. Is formed. For this reason, it is possible to form inner and outer ribs for improving the strength of the fuel tank, and to provide protrusions for attaching parts such as valves inside the tank and parts such as hoses outside the tank. Can be easily installed. Moreover, since it can form integrally when forming an inner surface resin layer and an outer surface resin layer, a protrusion part can be formed firmly.

  According to the seventh aspect of the present invention, a plurality of protrusions formed from the inner surface resin layer toward the inside of the tank are formed inside the upper tank portion and the lower tank portion, and a plurality of inner ribs are formed over the entire circumference in the width direction. The automotive fuel is a plurality of outer ribs formed on the outer surface of the outer surface resin layer over the entire circumference in the width direction and in the longitudinal direction. It is a tank.

In the present invention according to claim 7, a plurality of protrusions formed from the inner resin layer toward the inside of the tank are formed inside the upper tank portion and the lower tank portion, and a plurality of inner ribs are formed over the entire circumference in the width direction. It is. For this reason, the intensity | strength of the width direction inside a tank can be improved. The protruding portions formed from the outer surface resin layer toward the tank outward direction are outer ribs formed on the outer surface of the outer surface resin layer over the entire circumference in the width direction and the longitudinal direction. Therefore, a plurality of widthwise and longitudinal outer ribs extending over the entire circumference can be formed on the outer surface of the fuel tank, and the strength in both the widthwise and longitudinal directions can be improved.
By the reinforcing effect of both the inner rib and the outer rib, the wall thickness of the fuel tank can be reduced, which can contribute to the weight reduction of the vehicle.

  The eighth aspect of the present invention is an automotive fuel tank in which the lower tank portion of the inner surface resin layer is formed with ribs having substantially the same height as the thickness of the outer surface resin layer on the lower outer surface.

  In the present invention of claim 8, since the lower tank portion of the inner surface resin layer is formed with ribs having substantially the same height as the thickness of the outer surface resin layer on the lower outer surface, the thickness of the outer surface resin layer when molding is It can be controlled by the rib, and a fuel tank having a predetermined thickness can be formed.

  According to a ninth aspect of the present invention, there is provided a method for manufacturing a fuel tank for an automobile comprising an inner surface resin layer and an outer surface resin layer of a thermoplastic synthetic resin. The inner surface resin layer is formed by separately molding an upper tank portion and a lower tank portion, respectively. The outer peripheral resin layer is formed on the lower mold of the mold in a state in which the upper peripheral part of the upper tank and the lower tank part are united and integrally joined to each other, and the mold for molding the fuel tank is opened. A thermoplastic synthetic resin injecting or injecting a thermoplastic synthetic resin, placing the joined inner resin layer on the injected or injected thermoplastic synthetic resin, and constituting the outer resin layer on the upper surface of the inner resin layer Is injected or injected, and then the upper mold of the mold is completely closed and compression molded, and the method of manufacturing a fuel tank for automobiles.

  According to the ninth aspect of the present invention, in the method of manufacturing an automotive fuel tank comprising an inner surface resin layer and an outer surface resin layer of a thermoplastic synthetic resin, the inner surface resin layer is molded separately from the upper tank portion and the lower tank portion, respectively. did. For this reason, since an upper tank part and a lower tank part can be shape | molded separately, the hollow tank of a complicated shape can be formed easily. By molding by molding, an upper tank portion and a lower tank portion having high dimensional accuracy and high strength can be obtained. Therefore, the inner surface resin layer formed by combining the upper tank portion and the lower tank portion has a dimensional accuracy. A high precision and high strength product can be obtained.

Since the upper peripheral part of the upper tank part and the lower tank part are combined and integrally joined, the same resin can be welded, and the welding can be reliably performed over the entire peripheral part of the opening peripheral part of the inner surface resin layer. it can. Further, when the upper tank portion and the lower tank portion are formed of a resin having an excellent fuel permeation preventive property, the resin can also be made of a resin having an excellent fuel permeation preventive property even at the joint surface. Transmission and evaporation can be prevented.
The tank hollow body of the inner surface resin layer can be formed first, and then can be used as an insert when the outer surface resin layer is formed.

With the mold for molding the fuel tank opened, the thermoplastic synthetic resin constituting the outer resin layer is injected or injected into the lower mold of the mold. Thereby, the resin constituting the lower half of the outer resin layer can be placed in the lower mold.
The bonded inner surface resin layer is placed on the injected thermoplastic synthetic resin. Accordingly, the thermoplastic synthetic resin constituting the outer resin layer placed on the lower mold of the mold is still kept at a high temperature and can be fused integrally with the inner resin layer.

A thermoplastic synthetic resin constituting the outer resin layer is injected or injected onto the upper surface of the inner resin layer. Thereby, the resin constituting the upper half of the outer resin layer can be placed on the inner resin layer.
Thereafter, the upper mold of the mold is completely closed and compression molding is performed. Thus, the entire outer periphery of the inner resin layer can be integrally covered with the outer resin layer and molded. For this reason, the inner surface resin layer can be integrally covered with the outer surface resin layer having no bonding surface, and in particular, a tank having no bonding surface for the outer surface resin layer can also be formed at the bonding portion of the inner surface resin layer. Further, since the thermoplastic synthetic resin constituting the outer surface resin layer is compression-molded within a short time from injection or injection, the inner surface resin layer and the outer surface resin layer can be firmly fused, and the strength of the fuel tank can be increased. Can be raised.

  According to the present invention of claim 10, in the molding of the upper tank portion and the lower tank portion of the inner surface resin layer, an outer sheet having a fuel permeation preventing function is inserted into a mold for molding, and then the tank side resin layer of the inner surface resin layer Is molded, and a tank side resin layer is formed on the inner surface of each of the upper tank portion and the lower tank portion, and the outer sheet is formed on each outer surface.

  According to the present invention of claim 10, in the molding of the upper tank portion and the lower tank portion of the inner surface resin layer, an outer sheet having a fuel permeation preventing function is inserted into a mold for molding, and then the tank side resin layer of the inner surface resin layer The tank side resin layer was formed on the inner surface of each of the upper tank portion and the lower tank portion, and the outer sheet was formed on each outer surface. For this reason, even if the tank-side resin layer is formed of a thermoplastic synthetic resin having high rigidity, it is possible to prevent fuel permeation, reduce the thickness of the fuel tank wall, and reduce the tank weight. In addition, the outer sheet can be provided in close contact with the tank-side resin layer, and the fuel tank can be molded without tearing the outer sheet during compression molding, and fuel permeation can be prevented.

  According to the present invention of claim 11, when the thermoplastic synthetic resin for forming the outer resin layer is injected or injected and then the mold is closed and compression molding is performed, the front end surface of the upper mold outer frame is placed on the lower mold parting. This is a method for manufacturing a fuel tank for an automobile, which is brought into contact with a surface, and thereafter, a middle mold of an upper mold is lowered to perform compression molding.

In the present invention of claim 11, when the thermoplastic synthetic resin forming the outer surface resin layer is injected or injected, and then the mold is closed and compression molding is performed, the front end surface of the upper mold outer frame is moved to the lower mold parting. Make contact with the surface. For this reason, it can prevent that the material of an outer surface resin layer protrudes out of a metal mold | die by the outer frame of an upper mold | type during compression molding. In addition, the outer side surface of the outer resin layer can be formed with the upper outer frame.
Thereafter, since the upper mold is lowered and compression-molded, the middle mold can be molded by being guided by the outer frame and compressing the material of the outer resin layer.

  The invention according to claim 12 is for an automobile that compresses slower than the compression speed of normal compression molding when the thermoplastic synthetic resin forming the outer resin layer is injected or injected and then the mold is closed and compression molded. It is a manufacturing method of a fuel tank.

  In the present invention of claim 12, when the thermoplastic synthetic resin forming the outer resin layer is injected or injected, when the mold is closed and compression molding is performed, the compression is performed slower than the compression speed of normal compression molding. The force applied to the inner resin layer during compression molding can be reduced, and deformation of the inner resin layer can be prevented. In addition, the flow of resin in the outer resin layer can be ensured, and the outer resin layer is formed so as to cover the entire inner resin layer, so that the dimensions of the fuel tank can be accurately formed.

  According to a thirteenth aspect of the present invention, in the mold for molding the upper tank portion and the lower tank portion of the inner surface resin layer, a plurality of recesses that form protrusions protruding inward from the inner surface resin layer are provided, the upper tank portion and the lower tank portion. It is the manufacturing method of the fuel tank for motor vehicles provided over the perimeter of the width direction of the inner surface of this.

  In the present invention of claim 13, a plurality of recesses forming protrusions projecting inward from the inner surface resin layer are formed in the mold for molding the upper tank portion and the lower tank portion of the inner surface resin layer, and the upper tank portion and the lower tank portion. It was provided over the entire circumference in the width direction of the inner surface. For this reason, simultaneously with the compression molding of the upper tank portion and the lower tank portion, a plurality of projections projecting inward from the inner surface resin layer can be molded, and the strength of the fuel tank can be increased. It is possible to attach a valve or the like attached to the inside of the fuel tank to this protrusion.

  According to the fourteenth aspect of the present invention, the upper mold and the lower mold of the mold are provided with a plurality of recesses that form protrusions protruding from the outer surface resin layer in the tank outer direction, in the width direction and the longitudinal direction of the outer surface of the outer surface resin layer. It is a manufacturing method of the fuel tank for vehicles provided over the perimeter.

  According to the fourteenth aspect of the present invention, the upper mold and the lower mold of the mold are provided with a plurality of recesses that form protrusions protruding outward from the outer surface resin layer in the width direction and the longitudinal direction of the outer surface of the outer resin layer. It was provided over the entire circumference. For this reason, simultaneously with the compression molding of the outer surface resin layer, it is possible to mold the protruding portion that protrudes outward from the outer surface resin layer. In addition, since the concave portion is provided over the entire width in the width direction and the longitudinal direction of the outer surface resin layer, the material of the outer surface resin layer can flow in the concave portion during compression molding, and the outer surface resin layer is uniformly molded. And the strength of the fuel tank can be increased.

  In the fuel tank according to the present invention, the inner surface resin layer is formed by combining the upper tank portion and the opening peripheral portion of the lower tank portion which are separately formed separately and joined. For this reason, an upper tank part and a lower tank part can be shape | molded separately, and each can be shape | molded by injection molding, and a dimensional accuracy and a strong upper tank part and a lower tank part can be obtained. The outer resin layer is integrally formed so as to cover the entire outer periphery of the bonded inner resin layer. For this reason, the outer surface resin layer is integrally formed as a whole. Therefore, the strength of the joint portion of the inner surface resin layer can be ensured, and the permeation of fuel from the joint portion of the inner surface resin layer can be prevented.

  The fuel tank manufacturing method of the present invention can be reliably performed over the entire periphery of the opening peripheral edge of the inner surface resin layer because the opening peripheral edge of the upper tank and the lower tank are combined and integrally joined. In addition, all of the bonding surfaces can be made of a resin having excellent fuel permeation prevention properties, and fuel permeation and evaporation from the bonding surfaces can be prevented. The entire outer peripheral surface of the inner resin layer can be integrally covered with the outer resin layer, and a tank without the outer resin layer can be molded at the joint portion of the inner resin layer.

An automotive fuel tank 1 according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of the fuel tank 1 as viewed obliquely from above. FIG. 2 is a sectional view taken along line XX in FIG. FIG. 3 is an enlarged cross-sectional view of the joint portion at the peripheral edge of the opening of the fuel tank 1 in the circled portion A in FIG.

  The fuel tank 1 is formed of two layers, an inner surface resin layer 10 and an outer surface resin layer 20, and the inner surface resin layer 10 includes an upper tank portion 11 and a lower tank portion 16 that are separately formed. The inner resin layer 10 can be divided not only into two but also into three or more. On the inner surface of the upper tank portion 11, an inner rib 12 that is a protruding portion is integrally formed toward the inner direction of the fuel tank 1.

  A pump unit mounting hole 3 and a pipe mounting hole 4 are formed in the upper tank portion 11. The pump unit mounting hole 3 is a hole for mounting the pump unit inside the fuel tank 1, and the pipe mounting hole 4 is a hole for mounting a pipe for fuel injection.

As with the upper tank portion 11, the lower tank portion 16 is integrally formed with an inner rib 17 that is a protruding portion toward the inside of the fuel tank 1. As shown in FIG. 5, outer ribs 18 having a height substantially the same as the thickness of an outer surface resin layer 20 to be described later are integrally formed on the lower outer surface of the lower tank portion 16.
A valve (not shown) is attached to the inner rib 12 of the upper tank portion 11 before welding to the lower tank 16.

  As shown in FIG. 3, the opening peripheral edge portion 13 of the upper tank portion 11 and the opening peripheral edge portion 19 of the lower tank portion 16 are welded to the end surfaces of the opening peripheral edge portions 13 and 19, as will be described later in the manufacturing method. An inner surface resin layer 10 that forms an inner layer of a hollow tank is formed. When a resin excellent in fuel permeation prevention property is used for the inner surface resin layer 10, since the resin joins the resin and there is no gap, fuel permeation is prevented from the joined portion of the inner surface resin layer 10. be able to.

When a resin having excellent rigidity is used for the inner surface resin layer 10, an outer sheet 10 a having excellent fuel permeation prevention properties may be provided on the outer surfaces of the upper tank portion 11 and the lower tank portion 16.
In this way, the upper tank portion 11 and the lower tank portion 16 can be formed separately, and can be formed by injection molding or the like to obtain the upper tank portion 11 and the lower tank portion 16 having high dimensional accuracy and high strength. it can. Further, it is possible to easily attach the reinforcing ribs 12 and 17 and the built-in parts inside the upper tank portion and the lower tank portion.

  The outer surface resin layer 20 constituting the outer layer of the fuel tank 1 is formed with a predetermined thickness so as to completely cover the outer surface of the inner surface resin layer 10. Unlike the inner surface resin layer 10, the outer surface resin layer 20 does not form the upper portion and the lower portion separately, but forms the upper portion and the lower portion integrally at a time, as will be described later. For this reason, unlike the inner surface resin layer 10, the outer surface resin layer 20 has no joint portion and is integrally formed as a whole. Therefore, the strength of the joint portion of the inner surface resin layer 10 can be reinforced by the outer surface resin layer 20.

The protrusions provided on the outer surface of the outer resin layer 20 include an outer rib 21 and a hose clamp 5 as shown in FIG. The outer ribs 21 are integrally formed from the outer surface resin layer 20, and a plurality of outer ribs 21 are provided in the longitudinal direction and the width direction of the fuel tank 1. The outer rib 21 can improve the strength of the fuel tank 1. Similarly, the hose clamp 5 is integrally formed from the outer surface resin layer 20, and a plurality of hose clamps 5 are formed on the surface of the fuel tank 1. A fuel pipe (not shown) and a fuel evaporative gas transfer pipe (not shown) are fixed to the hose clamp 5.

  A tank mounting portion (not shown) having a bolt hole protruding from the side of the outer surface resin layer 20 to the outside of the fuel tank 1 can be provided. The tank attaching portions are provided at several places necessary for attaching the fuel tank 1 to the automobile. The fuel tank 1 can be attached to the vehicle body of the automobile by inserting bolts and nuts into the tank attachment portion.

  The upper tank portion 11 and the lower tank portion 16 of the inner surface resin layer 10 are made of an ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene when a thermoplastic synthetic resin excellent in fuel permeation prevention is used. At least one material among terephthalate, polyethylene terephthalate, and polyphenylene sulfite can be used. In this case, the inner surface resin layer 10 is excellent in fuel permeation preventing property and can prevent permeation of fuel from the fuel tank.

When the inner surface resin layer 10 is welded to the tank side resin layer and the outer sheet 10a is welded to the outer surface, the tank side resin layer can be formed from high density polyethylene (HDPE). A thermoplastic synthetic resin having fuel oil resistance and impact resistance and excellent strength can be used.
The outer sheet 10a may be a multilayer sheet including a layer made of at least one material selected from ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfite. EVOH or the like has an excellent fuel oil permeation preventing function, and even if it is a thin layer, it can prevent the fuel oil from permeating through the tank wall and evaporating into the atmosphere.
The outer sheet 10a has a thickness of about 1 mm for the entire three layers.

For example, when the tank side resin layer and the outer surface resin layer 20 are made of high density polyethylene (HDPE), the configuration of the outer sheet 10a is HDPE / modified polyethylene / ethylene vinyl alcohol copolymer (EVOH) / modified polyethylene / It can be HDPE. By adopting such a configuration, the outermost HDPE of the upper and lower outer layers of the outer sheet 10a and the HDPE constituting the inner surface resin layer 10 and the outer surface resin layer 20 described later can be easily fused during molding.
In addition, since EVOH and HDPE in the outer sheet 10a are fused in advance by modified polyethylene, the outer sheet 10a itself is not isolated, and the inner resin layer 11, the outer sheet 10a, and the outer resin layer 20 are combined. It can be firmly joined.

  Next, the outer surface resin layer 20 can be formed from high-density polyethylene (HDPE), and other than the high-density polyethylene (HDPE), it has fuel oil resistance and impact resistance, and uses a thermoplastic synthetic resin having excellent strength. can do. When high-density polyethylene (HDPE) is used, the strength is high, the walls of the outer resin layer 20 and the inner resin layer 10 do not need to be thickened, and the weight of the fuel tank 1 can be reduced. Moreover, since it is excellent in weather resistance, its strength can be maintained for a long period of time, and it is an olefinic thermoplastic synthetic resin that can be easily recycled.

Next, a method for manufacturing the fuel tank 1 will be described.
The fuel tank 1 molds the inner surface resin layer 10, and then compresses and molds the outer surface resin layer 20 integrally with the outer surface of the inner surface resin layer 10. The inner surface resin layer 10 is manufactured by separately molding the upper tank portion 11 and the lower tank portion 16 and then welding the opening peripheral portions 13 and 19 of the upper tank portion 11 and the lower tank portion 16. First, the manufacturing method of the upper tank part 11 and the lower tank part 16 is demonstrated. Although the manufacturing method of the upper tank part 11 and the lower tank part 16 is shape | molded by another metal mold | die, respectively, it is substantially the same, It demonstrates taking the case of the manufacturing method of the upper tank part 11 as an example.

As shown in FIG. 4, the upper tank portion 11 is molded by injection molding using an upper tank molding die 40. The thermoplastic synthetic resin constituting the upper tank portion 11 is injection-molded into the cavity 43 of the upper tank molding die 40, and then the movable die 42 is opened, and the upper tank portion 11 is taken out from the fixed die 41. At this time, as shown in FIG. 5, the inner rib 12 is simultaneously formed in the upper tank portion 11. By injection molding, the shape of the upper tank portion 11 can be accurately formed.
Similarly, the lower tank portion 16 is molded by injection molding using a lower tank molding die. As shown in FIG. 5, the lower tank portion 16 is formed with an inner rib 17 and an outer rib 18 at the same time.

Next, the upper tank part 11 and the lower tank part 16 are joined. As shown in FIG. 6, a hot plate 50 is applied to the opening peripheral edge portion 13 of the upper tank portion 11 and the opening peripheral edge portion 19 of the lower tank portion 16 to melt, and then the opening peripheral edge portions 13 and 19 are crimped together. Melting and joining.
Before joining the upper tank portion 11 and the lower tank portion 16, a valve (not shown) to be mounted inside the fuel tank 1 is attached to the upper tank 11.
The joined upper tank portion 11 and lower tank portion 16 form an inner surface resin layer 10 of the hollow fuel tank 1 as shown in FIG.

  When a thermoplastic synthetic resin excellent in fuel permeation prevention property is used for molding the inner surface resin layer 10, an ethylene vinyl alcohol copolymer (EVOH) or the like is used as described above. When the outer sheet 10a is used, the tank-side resin layer is formed of high-density polyethylene (HDPE), and the outer sheet 10a is formed from HDPE / modified polyethylene / EVOH / modified polyethylene / HDPE in order from the top. Can be used. In this case, as described later, it is possible to ensure the bonding between the tank-side resin layer of the inner surface resin layer 10 and the outer surface resin layer 20.

Next, the outer surface resin layer 20 is molded.
First, as shown in FIG. 8, a thermoplastic synthetic resin for forming the outer surface resin layer 20 is injected into the lower mold 34 of the mold 30 for forming the outer surface resin layer 20. The amount is an amount that can form a substantially lower half of the outer resin layer 20. The lower die 34 is provided with a recess 34b that forms the outer rib 21 of the fuel tank 1.

Thereafter, as shown in FIG. 9, the inner surface resin layer 10 is placed on the thermoplastic synthetic resin forming the outer surface resin layer 20 of the lower mold 34, and the inner surface resin layer 10 is pushed into the lower mold 34. At this time, a plurality of outer ribs 18 having a height substantially the same as the thickness of the outer resin layer 20 are provided on the lower surface of the inner resin layer 10, and the outer ribs 18 contact the inner surface of the lower mold 34, A space for forming the outer resin layer 20 is formed between the resin layer 10 and the lower mold 34. A thermoplastic synthetic resin for forming the outer surface resin layer 20 enters this space, and the outer surface resin layer 20 can be formed with a predetermined thickness.
At this time, the upper surface of the thermoplastic synthetic resin forming the outer surface resin layer 20 is positioned slightly lower than the outer peripheral end surface of the lower die 34 so as not to protrude from the lower die 34.

  Next, as shown in FIG. 10, a thermoplastic synthetic resin that forms the outer resin layer 20 is injected into the upper surface of the inner resin layer 10. The amount is an amount that can form substantially the upper half of the outer resin layer 20. However, in order to facilitate the subsequent molding of the thermoplastic synthetic resin of the outer resin layer 20, it is preferable that the outer resin layer 10 be placed on the widest possible surface of the inner resin layer 10. For this reason, you may inject | pour a thermoplastic synthetic resin in strip shape.

Thereafter, as shown in FIG. 11, the upper mold 31 is closed. To close the upper mold 31, first, the outer frame 32 that is the outer peripheral portion of the upper mold 31 is brought into contact with the outer peripheral portion of the lower mold 34. Accordingly, it is possible to prevent the thermoplastic synthetic resin of the outer resin layer 20 from protruding from the parting surface of the mold 30 during compression molding, and the outer frame 32 can form the side surface of the outer resin layer 20. .
Next, the middle mold 33 is moved downward, the inner resin layer 11 is sandwiched between the lower mold 34 and the upper mold 31, and the synthetic resin constituting the outer resin layer 20 is compressed to a thickness for forming the outer resin layer 20. And mold.

At this time, since the recess 33 b and the recess 34 b are formed in the middle mold 33 and the lower mold 34 of the upper mold 31, the outer rib 21 can be provided on the outer surface of the fuel tank 1.
At the time of compression molding, the material of the outer surface resin layer 20 can flow in the recesses 33b and 34b, the flow of the thermoplastic synthetic resin forming the outer surface resin layer 20 can be made smooth, and the wall of the fuel tank 1 can be While being able to shape | mold uniformly, the intensity | strength of the fuel tank 1 can be increased.
Note that the thermoplastic synthetic resin above and below the outer resin layer 20 is in a molten state, so that both fuse together during compression molding to form the fuel tank 1 having an integral appearance with no joint surface.

At this time, it is preferable that the moving speed of the middle mold 33 is slower than the moving speed in the normal compression molding. For example, the moving speed of the mold in the case of normal compression molding is 10 mm / second to 20 mm / second, but in the case of the present invention, it is preferably about 5 mm / second. Thus, when the moving speed of the mold is slowed, the force applied to the inner surface resin layer 10 when the thermoplastic synthetic resin moves laterally in the cavity during compression molding can be reduced, and the deformation of the inner surface resin layer 10 can be reduced. Can be prevented. Moreover, the flow of the thermoplastic synthetic resin of the outer surface resin layer 20 can be ensured, and the dimensions of the fuel tank 1 can be accurately formed.
Then, when the fuel tank 1 is molded by cooling, the mold 30 is opened and the fuel tank 1 is taken out.

The normal injection temperature of the thermoplastic synthetic resin (HDEP) constituting the outer resin layer 20 is 180 ° C. to 260 ° C., but in the present invention, it is injected or injected at a high temperature of about 260 ° C.
Since the resin temperature is maintained at a high temperature of about 260 ° C., it can be melted and fused with the inner surface resin layer 10 during molding. When the outer sheet 10a is used, the inner resin layer 10 and the HDEP constituting the outer resin layer 20 are melted and the inner resin layer 10 main body, the outer resin layer 20 and the multilayer sheet 10a are firmly welded. Can do.

It is the perspective view which looked at the fuel tank which is embodiment of this invention from diagonally upward. It is sectional drawing along the XX line of FIG. FIG. 3 is an enlarged cross-sectional view of a joint portion at an opening peripheral edge portion of the fuel tank 1 in a portion A circled in FIG. 2. It is sectional drawing of the metal mold | die which shape | molds the upper tank part of the inner surface resin layer which is embodiment of this invention. It is a cross-sectional schematic diagram before joining of the upper tank part and lower tank part of the fuel tank which is embodiment of this invention. It is a cross-sectional schematic diagram of the state which fuse | melts the upper peripheral part of the fuel tank which is embodiment of this invention, and the opening peripheral part of a lower tank part with a hot platen. It is a cross-sectional schematic diagram of the state which fuse | fused the upper tank part of the fuel tank which is embodiment of this invention, and the opening peripheral part of the lower tank part. It is a cross-sectional schematic diagram which shows the state which inject | poured the thermoplastic synthetic resin which forms an outer surface resin layer into the lower mold | type of the metal mold for shaping | molding of the fuel tank which is embodiment of this invention. It is a cross-sectional schematic diagram which shows the state which inject | poured the thermoplastic synthetic resin which forms an outer surface resin layer in the lower mold | type of the metal mold | die for fuel tank which is embodiment of this invention, and pushed in the inner surface resin layer. FIG. 3 is a schematic cross-sectional view showing a state in which a thermoplastic synthetic resin for forming an outer surface resin layer is injected into the upper surface of an inner surface resin layer pushed into a lower mold of a fuel tank molding die according to an embodiment of the present invention. . It is a cross-sectional schematic diagram which shows the state which closed the upper mold | type and lower mold | type of the metal mold | die for a fuel tank which is embodiment of this invention, and formed the outer surface resin layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 10 Inner surface resin layer 11 Upper tank part 12, 17 Inner rib 16 Lower tank 20 Outer surface resin layer 21 Outer rib 30 Mold 31 Upper mold 32 Outer frame 33 Middle mold 34 Lower mold

Claims (14)

In an automotive fuel tank formed from an inner surface resin layer and an outer surface resin layer made of thermoplastic synthetic resin,
The inner surface resin layer is formed by combining the respective opening peripheral portions of the upper tank portion and the lower tank portion which are separately molded separately.
The fuel tank for automobiles, wherein the outer resin layer is integrally formed so as to cover the entire outer periphery of the joined inner resin layer.   The automotive fuel tank according to claim 1, wherein the inner surface resin layer is formed from a thermoplastic resin having fuel permeation prevention performance, and the outer surface resin layer is formed from a thermoplastic resin having rigidity.   The outer surface resin layer is formed of high density polyethylene (HDPE), and the inner surface resin layer is at least one of ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfite. The automobile fuel tank according to claim 1 or 2, wherein the fuel tank is formed of a kind of material.   The inner resin layer includes a tank-side resin layer formed of a rigid thermoplastic synthetic resin inside the upper tank portion and the lower tank portion, respectively, and an outer sheet for preventing fuel permeation outside the tank-side resin layer. The automobile fuel tank according to claim 1, which is integrally formed.   The tank side resin layer and the outer surface resin layer of the inner surface resin layer are formed of high density polyethylene (HDPE), and the outer sheet is made of ethylene vinyl alcohol copolymer (EVOH), polyacetal, nylon, polybutylene terephthalate, polyethylene terephthalate, 5. The fuel tank for automobiles according to claim 4, which is a multilayer sheet including a layer made of at least one material of polyphenylene sulfite.   The projecting portion is integrally formed from the inner surface resin layer toward the tank inward direction, and the projecting portion is integrally formed from the outer surface resin layer toward the tank outer direction. 6. The fuel tank for automobiles according to any one of 5 above.   Each of the protrusions formed from the inner surface resin layer toward the inside of the tank is an inner rib formed in the upper tank portion and the lower tank portion, and a plurality of inner ribs are formed over the entire circumference in the width direction. The projecting portion formed from the outer surface resin layer toward the outer side of the tank is an outer rib formed on the outer surface of the outer surface resin layer over the entire circumference in the width direction and the longitudinal direction. The fuel tank for automobiles according to any one of claims 1 to 6.   The automobile fuel tank according to any one of claims 1 to 7, wherein the lower tank portion of the inner surface resin layer is formed with a rib having a height substantially equal to a thickness of the outer surface resin layer on a lower outer surface. In the method of manufacturing a fuel tank for automobiles composed of an inner surface resin layer and an outer surface resin layer of thermoplastic synthetic resin,
The inner surface resin layer is formed by separately molding the upper tank portion and the lower tank portion separately, and uniting and integrally bonding the opening peripheral portions of the upper tank portion and the lower tank portion,
With the mold for molding the fuel tank opened, a thermoplastic synthetic resin constituting the outer resin layer is injected or injected into the lower mold of the mold, and the injected or injected thermoplastic synthetic resin is Place the bonded inner surface resin layer,
Injecting or injecting a thermoplastic synthetic resin constituting the outer resin layer on the upper surface of the inner resin layer,
Thereafter, the upper mold of the mold is completely closed and compression-molded, and a method for manufacturing an automobile fuel tank is provided.   In the molding of the upper tank portion and the lower tank portion of the inner surface resin layer, after inserting an outer sheet having a fuel permeation preventing function into the mold for molding, the tank side resin layer of the inner surface resin layer is molded, The manufacturing method of the fuel tank for motor vehicles according to claim 9 which formed a tank side resin layer in each inner surface of said upper tank part and a lower tank part, and formed said outside sheet in each outer surface.   After injecting or injecting the thermoplastic synthetic resin that forms the outer surface resin layer, when the mold is closed and compression molding is performed, the tip surface of the outer frame of the upper mold is brought into contact with the parting surface of the lower mold The method for manufacturing a fuel tank for an automobile according to claim 9 or 10, wherein after that, the middle mold of the upper mold is lowered to perform compression molding.   12. The method according to claim 9, wherein after injection or injection of the thermoplastic synthetic resin forming the outer surface resin layer, when the mold is closed and compression molding is performed, the compression is performed slower than the compression speed of normal compression molding. The manufacturing method of the fuel tank for motor vehicles in any one.   A mold for forming the upper tank portion and the lower tank portion of the inner surface resin layer is provided with a plurality of recesses that form protrusions protruding inward from the inner surface resin layer in the width direction of the inner surfaces of the upper tank portion and the lower tank portion. The manufacturing method of the fuel tank for motor vehicles in any one of Claim 9 thru | or 12 provided over the perimeter.   The upper and lower molds of the mold are provided with a plurality of recesses that form protrusions protruding outward from the tank from the outer surface resin layer over the entire circumference in the width direction and the longitudinal direction of the outer surface of the outer surface resin layer. Item 14. A method for manufacturing an automobile fuel tank according to any one of Items 9 to 13.

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