JP2009113704A - Fuel tank made of thermoplastic synthetic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel tank made of a thermoplastic synthetic resin which has a great rigidity, facilitates the production thereof, and enables the reduction of cost. <P>SOLUTION: In the fuel tank 1 made of the thermoplastic synthetic resin which is formed by a blow molding, bead parts 10 which protrude from the outer wall of the fuel tank 1 toward the inside thereof are formed. Each bead part 10 has a plurality of bead convex parts 11 with a large height protruding toward the inside and a plurality of bead concave parts 12 with a small height protruding toward the inside which are alternately successively formed in a lateral direction along the outer wall. The bead convex part 11 has at the inside thereof hollow parts 13 opened to the outer surface of the fuel tank 1 and the bead concave part 12 has connection parts 14 formed by the adhesion of side surfaces at the inside thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel tank made of thermoplastic synthetic resin formed by blow molding.

Conventionally, the structure of fuel tanks for automobiles and the like has been made of metal, but in recent years, thermoplasticity has been achieved by reducing the weight of the vehicle, eliminating rust, and easily forming into a desired shape. Those made of synthetic resin 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 parison of a molten thermoplastic synthetic resin member 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.

  In the fuel tank 101 formed by blow molding, a bead portion 110 protruding inward from the outer wall is formed in order to increase the rigidity of the outer wall. In order to form this bead portion 110, as shown in FIG. 8A, a parison introduced into the blow molding die 120 with a blow molding rib 121 protruding from the inner surface of the blow molding die 120. The air tank 8 is blown and inflated, and the parison 8 is pressed against the cavity of the blow mold 120 and the blow mold rib 121 to form the fuel tank 101 at the same time. Thereafter, the fuel tank 101 is removed from the blow mold 120 and the blow mold rib 121 is removed from the outer wall of the fuel tank 101 to complete the molding.

  Further, as shown in FIGS. 8B and 8C, the blow mold rib 121 is slid and driven so that the blow mold rib 121 of the blow mold 120 can be easily taken out from the parison 8. Some of them are made to recede from the inner surface of the molding die 120 (see, for example, Patent Document 1). However, the blow mold 120 has a complicated slide structure, the price of the mold rises, the molding time becomes longer due to the slide time, and the cost increases.

Further, since the bead part 110 is molded by the blow molding die rib 121, a bead part hollow part 113 that opens to the outer surface of the outer wall of the fuel tank 101 is formed in the corresponding part.
And when the outer wall of the fuel tank 101 is deformed, the bead portion hollow portion 113 is opened, the rigidity of the bead portion 110 in the direction perpendicular to the bead portion 110 is lowered, and the strength of the outer wall may be lowered. is there.

Therefore, as shown in FIG. 9, the insert member 215 is attached to the bead portion hollow portion 213 of the bead portion 210 and the side walls on both sides of the bead portion hollow portion 213 are connected to prevent the bead portion hollow portion 213 from opening. (For example, refer to Patent Document 2).
However, in this case, the insert member 215 needs to be molded in advance, and the insert member 215 needs to be blow-molded by being attached to the tip of the mold rib of the blow-molding mold. Has also increased.
Japanese Patent Laid-Open No. 5-305651 Japanese Utility Model Publication No. 63-21145

  Therefore, an object of the present invention is to provide a fuel tank made of a thermoplastic synthetic resin that has a large tank rigidity, is easy to manufacture, and is inexpensive.

In order to solve the above problems, the present invention of claim 1 is directed to a fuel tank made of thermoplastic synthetic resin formed by blow molding.
A bead portion that protrudes from the outer wall of the fuel tank toward the inside is formed, and the bead portion has a high bead portion protrusion that protrudes toward the inside and a bead portion recess that protrudes toward the inside. Are alternately formed along the outer wall in the lateral direction, the bead portion convex portion has a hollow portion opened in the outer surface of the fuel tank inside, and the bead portion concave portion has the inner side surfaces facing each other. A fuel tank made of a thermoplastic synthetic resin, characterized in that a connecting portion is formed by fusing.

In the present invention of claim 1, since the bead portion protruding from the outer wall of the fuel tank toward the inside is formed, the strength of the outer wall of the fuel tank can be increased, the impact from the outside of the fuel tank, Deformation due to expansion or the like due to an increase in internal pressure can be prevented. The bead portion can reduce the thickness of the outer wall of the fuel tank, thereby reducing the tank weight.
Further, since the bead portion is formed inside the fuel tank, it is possible to save the mounting space of the fuel tank and to prevent the bead portion from being damaged.

The bead part is formed with a plurality of bead part convex parts having a high height projecting toward the inside and a bead part concave part having a low height projecting toward the inside alternately in a horizontal direction along the outer wall. did. For this reason, the fuel tank can be formed on the outer wall of the fuel tank by blow molding with a predetermined length, and at the same time, the bead portion can be formed, and the manufacturing is easy, and the strength is increased over the wide length of the outer wall. can do. Moreover, the hollow part of a bead part can be connected with a predetermined space | interval so that it may mention later.
The bead concave portion also protrudes toward the inside of the fuel tank, and has a reinforcing effect on the outer wall of the fuel tank as a bead portion, and the bead convex portion and the bead concave portion are integrally connected. A reinforcement effect can be show | played in the whole bead part combining a part convex part and a bead part recessed part.

  The bead convex portion has a hollow portion opened on the outer surface of the fuel tank inside, and the bead concave portion has a connecting portion formed by fusing the inner outer wall. For this reason, when the outer wall of the fuel tank is bent by the connecting portion, the opening of the hollow portion of the bead portion can be prevented from opening, and the rigidity of the outer wall can be increased. Simultaneously with the formation of the bead portion of the fuel tank, the hollow portion and the connecting portion can be formed at a predetermined interval, so that no additional parts are required and manufacturing is easy.

  According to the second aspect of the present invention, the bead portion is formed to protrude to the inside of the fuel tank by a rib formed to protrude from the inner surface of the blow molding die, and the rib is formed with a crest and a trough at predetermined intervals. Is a fuel tank made of a thermoplastic synthetic resin in which the bead convex portions are formed at the peak portions and the bead concave portions are formed at the valley portions.

In the present invention of claim 2, since the bead portion is formed to protrude inside the fuel tank by a rib formed to protrude from the inner surface of the blow molding die, a slide structure can be used for the blow molding die. Therefore, the mold structure can be simplified.
The ribs are alternately formed with crests and troughs at a predetermined interval, and the above-mentioned bead protrusions are formed at the crests, and the bead recesses are formed at the troughs, thus forming the rib troughs. Only by doing this, the bead portion recess can be formed and the bead portion connecting portion can be connected to the opening of the bead portion hollow portion.

  The present invention of claim 3 is a fuel tank made of a thermoplastic synthetic resin in which the lateral width of the bead portion concave portion is smaller than the lateral width of the bead portion convex portion.

  In the present invention of claim 3, since the width of the bead portion recess is smaller than the width of the bead portion protrusion, the height of the bead portion recess can be maintained at a predetermined dimension or more, and the bead portion has a reinforcing effect. While being able to maintain, the opening of a bead part hollow part can be connected with the connection part of a bead part recessed part.

  According to a fourth aspect of the present invention, the bead portion is a thermoplastic synthetic resin fuel tank formed on the upper wall and the lower wall of the fuel tank, respectively.

  In the present invention of claim 4, since the bead portions are respectively formed on the upper wall and the lower wall of the fuel tank, the rigidity of both the upper wall and the lower wall of the fuel tank is increased and the strength of the entire fuel tank is increased. Can be made.

  The present invention of claim 5 is a fuel tank made of a thermoplastic synthetic resin, wherein the outer wall has at least an outer layer, an inner layer, and a barrier layer therebetween.

  In the present invention of claim 5, since the outer wall has at least the outer layer, the inner layer, and the barrier layer therebetween, a material that secures the strength of the fuel tank is used for the outer layer, and a material that has fuel oil resistance and strength is used for the inner layer. In addition, a fuel permeation preventive material is used for the barrier layer, so that the strength of the fuel tank can be improved and the permeation of fuel can be prevented. If a material having good adhesion between the outer layer and the inner layer is used for the barrier layer, a fuel tank having a high strength in which the three layers are firmly bonded can be obtained.

In the present invention, the bead portion includes a bead portion convex portion with a high height protruding toward the inside and a bead portion concave portion with a low height protruding toward the inside, which are alternately continued along the outer wall in the lateral direction. Therefore, the bead portion can be formed at the same time as the fuel tank is formed, the manufacturing is easy, and the strength can be increased over a wide length of the outer wall.
The bead convex portion has a hollow portion opened on the outer surface of the fuel tank inside, and the bead concave portion has a connecting portion formed by fusing the inner outer wall, so the outer wall of the fuel tank is bent. The opening of the bead portion can be prevented from opening, and the rigidity of the outer wall can be increased.

A fuel tank according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view seen from the top of a fuel tank 1 according to an embodiment of the present invention. FIG. 2 is a perspective view of the fuel tank 1 according to the embodiment of the present invention cut from the upper half after cutting, and FIG. 3 is a perspective view of the entire fuel tank 1 of the embodiment of the present invention as viewed from above. FIG. 3 is a perspective view showing a portion where a bead portion 10 is formed on a lower wall 3 by a dotted line. 4 is a cross-sectional view taken along line AA in FIG. 2, and is a cross-sectional view showing a state of the blow molding die 20 and the outer wall of the fuel tank 1 when the fuel tank 1 is molded by blow molding. 5 is a cross-sectional view taken along line BB in FIG. 4, and FIG. 6 is a cross-sectional view taken along line CC in FIG. FIG. 7 is a perspective view of one side of the blow molding die 20 as viewed from above.

  In the embodiment of the present invention, the fuel tank 1 made of thermoplastic synthetic resin is formed by blow molding. In the blow molding, as described in FIG. 8 of the prior art, the parison 8 is introduced into the cavity 24 of the blow molding die 20, air is blown into the parison 8, inflated, and pressed against the inner surface of the cavity 24. Then, the fuel tank 1 is formed. In the fuel tank 1, an upper wall 2 and a lower wall 3 are integrally formed at the same time.

  As shown in FIG. 1, a fuel tank opening 4 for mounting a fuel pump (not shown) and other equipment is formed in the outer wall of the upper wall 2 of the fuel tank 1. A bead portion 10 to be described later is formed on the inner surface, and an opening of a bead portion hollow portion 13 to be described later is formed side by side on the outer surface of the outer wall corresponding to the bead portion 10. Similarly, on the outer wall of the lower wall 3 of the fuel tank 1, the bead portion 10 is formed on the inner surface of the outer wall, and the opening of the bead portion hollow portion 13 is aligned with the outer surface of the outer wall.

As shown in FIG. 4, the outer wall of the fuel tank 1 is composed of three layers: an outer layer 5, an inner layer 6, and a barrier layer 7 formed between the outer layer 5 and the inner layer 6. In blow molding, the parison 8 composed of the above three layers is used.
The outer layer 5 and the inner layer 6 are made of a thermoplastic synthetic resin that has high strength and maintains strength against fuel oil, and the barrier layer 7 is made of a thermoplastic synthetic resin that has very little permeation of fuel oil. .

  The thermoplastic synthetic resin constituting the outer layer 5 and the inner layer 6 is, for example, high density polyethylene (HDPE), polyoxymethylene (POM), ethylene vinyl alcohol copolymer (EVOH), nylon, polybutylene terephthalate, polyethylene terephthalate, polyphenylene. At least one material of sulfide can be used.

As the thermoplastic synthetic resin constituting the barrier layer 7, for example, ethylene vinyl alcohol copolymer (EVOH), polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide (PPS) can be used.
It should be noted that layers having good adhesion to high-density polyethylene (HDPE) or the like, for example, an adhesive layer of modified polyethylene (m-PE) or the like are interposed on both sides of the barrier layer 7 such as the ethylene vinyl alcohol copolymer (EVOH). The use of a multi-layer parison is preferable because the adhesion between the three layers is improved.

  As shown in FIG. 2, a bead portion 10 that protrudes from the outer wall of the fuel tank 1 toward the inside is formed inside the fuel tank 1. Although FIG. 2 shows the lower wall 3 of the fuel tank 1, the bead portion 10 is similarly formed in the upper wall 2 toward the inside. As will be described later, the bead portion 10 can be formed simultaneously with blow molding. In the embodiment of FIG. 2, the lower wall 3 is bent, but the bead portion 10 is formed along the bent surface also on the bent surface.

  The bead portion 10 is formed integrally and continuously in the longitudinal direction of the fuel tank 1. Moreover, it is preferable to form a plurality of bead portions 10 in parallel. In the embodiment shown in FIG. 2, three are formed in the longitudinal direction. As a result, the rigidity can be increased in the longitudinal direction of the fuel tank 1 and the rigidity can be increased over the entire outer wall of the fuel tank 1 over the entire outer wall.

  By increasing the strength of the outer wall of the fuel tank 1, the fuel tank 1 is caused by an external impact applied to the fuel tank 1, or when the temperature inside the fuel tank 1 rises and expands due to an increase in internal pressure. Can be prevented from being deformed. Further, since the bead portion 10 is formed inside the fuel tank 1, it is possible to save the mounting space of the vehicle body to which the fuel tank 1 is attached and to prevent the bead portion 10 from being damaged.

  As shown in FIG. 3, the upper wall 2 and the lower wall 3 are formed integrally with the bead portion 10, and four bead portions 10 are formed on the lower wall 3 in the longitudinal direction. The lower wall 3 of the fuel tank 1 is not flat but has a step 3b. The bead portion 10 is also formed continuously along the outer wall at the step 3b. A step 3b and a curved surface can also be formed on the upper wall 2, and in this case, the upper wall 2 of the fuel tank 1 can also ensure rigidity.

  As shown in FIGS. 2 and 4, the bead portion 10 alternately includes a bead portion convex portion 11 having a high height protruding toward the inside and a bead portion concave portion 12 having a low height protruding toward the inside. A plurality of pieces are formed in a continuous manner along the outer wall in the lateral direction. Since the bead recess 12 has a predetermined height from the outer wall of the fuel tank 1, similarly to the bead protrusion 11, the bead recess 12 is also rigid against bending of the outer wall of the fuel tank 1. Even if the bead portion concave portion 12 is low, the bead portion 10 as a whole can have rigidity, and the strength can be increased over a wide length of the outer wall.

  The bead portion convex portion 11 has a bead portion hollow portion 13 opened in the outer surface of the outer wall of the fuel tank 1 inside. In the bead portion recess 12, the inner wall surface is fused to form a bead portion connecting portion 14. And the bead part hollow part 13 and the bead part connection part 14 are integrally formed alternately continuously. For this reason, even if force is applied to the outer wall of the fuel tank 1, the bead portion connecting portion 14 can prevent the opening of the bead portion hollow portion 13 of the bead portion 10 from being opened, and the rigidity of the outer wall can be increased.

Formation of this bead part 10 is demonstrated based on FIGS.
The blow molding die 20 is formed by combining two surfaces to form a cavity 24, and the parison 8 is introduced into the cavity 24, and air is blown into the parison 8, and the parison 8 presses against the inner surface of the cavity 24. As a result, the fuel tank 1 is formed.
Ribs 21 are formed on the inner surface of the blow mold 20 in order to form the bead portion 10 of the fuel tank 1.

  As shown in FIG. 7, the rib 21 is formed so as to protrude from the inner surface of the cavity 24. The rib 21 is formed such that the rib valley portions 22 and the rib crest portions 23 are alternately arranged in the horizontal direction, and the rib crest portion 23 has a width greater than that of the rib trough portion 22. For example, the lateral width of the rib crest portion 23 is formed to about 20 mm to 50 mm, and the lateral width of the rib valley portion 22 is formed to about 3 mm to 8 mm. The height of the rib crest 23 is about 10 mm to 30 mm. The rib valley portion 22 is formed at substantially the same height as the inner surface of the cavity 24. The thickness of the rib 21 is about 2 mm to 5 mm.

  The ribs 21 are merely formed so as to protrude from the cavities 24, and a slide structure is not used for the blow molding mold 20, and the mold structure can be simplified. For this reason, the molding cycle time of blow molding can be shortened, and the price of the mold can be reduced.

  When the parison 8 is introduced into the blow-molding mold 20 and blown into the blow mold 20 to be inflated and pressed against the inner surface of the cavity 24, the parison 8 is pressed around the rib 21 as shown in FIG. 4. Then, as shown in FIG. 5, the parison 8 wraps around the rib crest 23 at the rib crest 23 to form the bead convex part 11, and the rib trough 22 as shown in FIG. 6. Thus, the bead portion concave portion 12 is formed continuously with the bead portion convex portion 11.

  Since the lateral width of the rib valley portion 22 is narrower than the lateral width of the rib crest portion 23, the bead portion concave portion 12 is formed slightly lower than the bead portion convex portion 11, and is continuous with the bead portion convex portion 11. The bead part 10 can be formed, and the bead part 10 can have strength against compression or pulling from the lateral direction. Since the rib 21 does not prevent the parison 8 from being welded in the bead portion recess 12, both side surfaces of the bead portion recess 12 are in close contact with each other to form the bead portion connecting portion 14. For this reason, the bead part recessed part 12 does not have a hollow part.

When the fuel tank 1 is removed from the blow molding die 20 after molding, the bead portion convex portion 11 forms a bead portion hollow portion 13 in a portion where the rib crest portion 23 exists. The bead portion hollow portion 13 is formed to open on the outer surface of the outer wall of the fuel tank 1. For this reason, on the outer surface of the fuel tank 1, as shown in FIG. 1, the upper wall 2 and the lower wall 3 are formed side by side with openings of bead portion hollow portions 13.
Since the rib crest portion 23 is formed to be thin, the bead portion hollow portion 13 is not large, and the capacity of the fuel tank 1 can be reduced even if the bead portion 10 protrudes into the fuel tank 1. Few.

  As shown in FIG. 5, the outer wall of the fuel tank 1 is composed of three layers of the outer layer 5, the inner layer 6, and the barrier layer 7 without breaking the parison 8 as shown in FIG. ing. For this reason, also in the bead part convex part 11, the intensity | strength of the fuel tank 1 and fuel permeation | blocking prevention property can be maintained.

  In the rib valley portion 22, as shown in FIG. 6, the portions of the outer layer 5 of the parison 8 are welded together to form an integrally connected bead portion connecting portion 14, and there is no hollow portion. Since the outer layer 5 is welded to each other, the bead portion connecting portion 14 has a high strength and the bead portion connecting portion 14 does not open. Thus, since the bead part 10 has the bead part convex part 11 and the bead part recessed part 12 formed alternately, even if the outer wall of the fuel tank 1 bends, the bead part connecting part 14 is not the bead part hollow part 13. The opening can be prevented from opening.

For this reason, the rigidity of the bead part 10 can be improved, the strength of the outer wall of the fuel tank 1 can be improved, and the thickness of the outer wall can be reduced. Therefore, the weight of the fuel tank 1 can be reduced and it can contribute to weight reduction of a vehicle.
Moreover, the bead part connection part 14 can be formed simultaneously with the blow molding of the fuel tank 1 and is easy to manufacture.
Further, depending on the shape of the fuel tank 1, the bead portion 10 may be disposed in the short direction of the fuel tank 1, or may be disposed in an oblique direction or a C shape of the fuel tank 1.

It is the perspective view seen from the upper part of the fuel tank which is embodiment of this invention. It is the perspective view seen from the upper part, after cut | disconnecting the lower half of the fuel tank of embodiment of this invention. It is the perspective view seen from the upper part of the fuel tank of other embodiment of this invention. It is sectional drawing along the AA line in FIG. 2 at the time of shaping | molding of the fuel tank of embodiment of this invention. FIG. 5 is a cross-sectional view of the fuel tank according to the embodiment of the present invention taken along line BB in FIG. 4. It is sectional drawing along CC line in FIG. It is a perspective view of the state where one metallic mold of a blow molding metallic mold used for implementation of the present invention was opened. It is sectional drawing of the blow molding metal mold | die of the conventional fuel tank. It is sectional drawing of the bead part of the other conventional fuel tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Outer layer 3 Inner layer 4 Barrier layer 10 Bead part 11 Bead part convex part 12 Bead part concave part 13 Bead part hollow part 14 Bead part connection part 20 Blow molding die 21 Rib 22 Rib trough part 23 Rib mountain part

Claims (5)

In a fuel tank made of thermoplastic synthetic resin formed by blow molding,
A bead portion that protrudes from the outer wall of the fuel tank toward the inside is formed, and the bead portion has a bead portion convex portion that protrudes toward the inside and a bead portion that protrudes toward the inside and has a low height. A plurality of concavities are formed alternately in the lateral direction along the outer wall, and the bead convex part has a hollow part opened to the outer surface of the fuel tank inside, and the bead concave part is A fuel tank made of a thermoplastic synthetic resin, wherein the inner side surfaces are fused together to form a connecting portion.   The bead portion is formed to protrude to the inside of the fuel tank by a rib formed to protrude from the inner surface of the blow mold, and the rib is alternately formed with crests and troughs at a predetermined interval. The fuel tank made of a thermoplastic synthetic resin according to claim 1, wherein the bead portion convex portion is formed at the peak portion, and the bead portion concave portion is formed at the valley portion.   The fuel tank made of a thermoplastic synthetic resin according to claim 1 or 2, wherein a lateral width of the bead portion concave portion is smaller than a lateral width of the bead portion convex portion.   The thermoplastic synthetic resin fuel tank according to any one of claims 1 to 3, wherein the bead portion is formed on an upper wall and a lower wall of the fuel tank, respectively.   The fuel tank made of a thermoplastic synthetic resin according to any one of claims 1 to 4, wherein the outer wall includes at least an outer layer, an inner layer, and a barrier layer therebetween.

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