Patent ID: 12227066

DESCRIPTION OF EMBODIMENTS

First Embodiment

<<Fuel Tank According to Embodiment>>

The fuel tank T shown inFIG.1is intended for installation in vehicles such as automobiles, motorcycles, and boats, and mainly includes a tank main body Ta and an internal component6. As shown inFIG.1, the present embodiment exemplifies a columnar reinforcement member as the internal component6to maintain the strength of the fuel tank T, but the internal component6can also be a valve or a wave damping plate. The terms “up and down” and “left and right” in the following description refer to the arrows inFIG.1. Each direction is defined for the convenience of the description and does not limit the present invention. The left and right directions inFIG.1correspond to the opening and closing directions of a pair of molds used to manufacture the fuel tank T.

The tank main body Ta is a hollow container made of resin for storing fuels such as gasoline, and has a multilayered structure that includes a barrier layer, for example. The tank main body Ta is primarily made of thermoplastic resin such as polyethylene or high-density polyethylene. The tank main body Ta is formed, for instance, by blow molding.

In reference toFIGS.2to4, the configuration of the internal component6will be described. A parison S which is a precursor of the tank main body Ta (seeFIG.5) has a multilayered structure of made HDPE (high-density polyethylene), EVOH (ethylene-vinyl alcohol copolymer), adhesive layers, and the like.

As shown inFIG.2, the internal component6includes a cylindrical torso portion6a, shoulder portions6b,6bformed at both left and right ends of the torso portion6a, neck portions6c,6cformed at the left and right outsides of the shoulder portions6b,6b, and head portions6d,6d. The structure of the internal component6is symmetrical in left and right (up and down on the paper). Therefore, unless explicitly stated, only one side will be described here. In the description of the internal component6, the surface facing the torso portion6ais referred to as the “back surface,” and the surface opposite to the “back surface” is referred to as the “front surface.”

The torso portion6ashown inFIG.2is a part configured to be the main body of the internal component6. Multiple hollowing holes may be formed in the torso portion6a. These hollowing holes (not shown) are formed to reduce weight and improve moldability, as well as increase the capacity of the fuel tank T (seeFIG.1).

The shoulder portion6bshown inFIG.2covers the recess3dof the first mold3or the recess4dof the second mold4, shown inFIG.5. The shape and size of the shoulder portion6bare not particularly limited, as long as they can cover the recesses3d,4d. Here, the shoulder portion6bhas a thin circular plate shape, and as shown inFIG.3, the outer diameter rb of the shoulder portion6bis larger than the outer diameter ra of the torso portion6a.

The neck portion6cshown inFIG.2is a portion connecting the shoulder portion6band the head portion6d, and as shown inFIG.3, the neck portion6chas a smaller diameter than the shoulder portion6band the head portion6d. The neck portion6chere stands from the surface6fof the shoulder portion6band has a cylindrical shape. Rounded corners (radii) are formed in the corner portions formed by the shoulder portion6band the neck portion6c, and in the corner portions formed by the head portion6dand the neck portion6c.

The head portion6dshown inFIG.2has a shape of a thick circular plate, which is thicker than the shoulder portion6b. However, the relationship in thickness between the shoulder portion6band the head portion6dhere is merely illustrative, and the shoulder portion6bcan also be formed thicker than the head portion6d. As shown inFIG.3, the outer diameter rd1of the head portion6dis larger than the outer diameter rc of the neck portion6cand smaller than the outer diameter rb of the shoulder portion6b. Due to this shape, a gap6jis formed between the shoulder portion6band the head portion6d, with the neck portion6cas the bottom portion. The gap6jis a portion where the parison S enters during molding. The part corresponding to the parison S wrapped around the neck portion6cwill be referred to as the “parison equivalent portion W” (seeFIG.7).

The shape of the head portion6dhas a rotation-stopping shape to prevent the internal component6from rotating along the circumferential direction of the head portion6d. This rotation-stopping shape, as shown inFIG.4, has an elliptical shape or substantially elliptical shape in the present embodiment. An outer diameter rd1of the head portion6din the vertical direction is larger than an outer diameter rd2of the head portion6din the horizontal direction.

The term rotation-stopping shape implies such a shape that after the internal component6is shaped onto the tank main body Ta, the internal component6will not rotate relative to the tank main body Ta. In the present embodiment, by making a difference in diameter between the outer diameter rd1and the outer diameter rd2of the head portion6d, the rotation of the internal component6is restrained. The rotation-stopping shape can also be, for example, an oval shape. The oval shape includes, for instance, an elongated circle shape, a flattened circle shape, or a rectangle with rounded corners.

<<Method for Manufacturing Fuel Tank According to Embodiment>>

The fuel tank manufacturing device1shown inFIG.5is a device that blow-molds a cylindrical parison S to produce a fuel tank T having an internal component6(seeFIG.1). Additionally, the fuel tank T can also be manufactured by molding a sheet-shaped parison (not shown).

As shown inFIG.5, the fuel tank manufacturing device1mainly includes a die2, a pair of first mold3and second mold4, and an elevator5that moves up and down between the first mold3and the second mold4.

The die2is located above the first mold3and second mold4and is a supply means for supplying the parison S to the first mold3and second mold4. The parison S has a multilayered structure composed of HDPE (high-density polyethylene), EVOH (ethylene-vinyl alcohol copolymer), adhesive layers, and the like, and is a precursor of the tank main body Ta that constitutes the fuel tank T (seeFIG.1).

The first mold3and second mold4shown inFIG.5are molding means for compression-molding the fuel tank T (seeFIG.1). The first mold3and second mold4are arranged facing each other, and concave molding portions3a,4aare formed on their opposing surfaces. The first mold3and second mold4can open and close by moving in the left-right direction, and the parison S is supplied when the first mold3and the second mold4are in an open state (state as shown inFIG.7). Also, the first mold3and second mold4include not-shown blow pins to send air into the first mold3and second mold4, and the air pressure (blow pressure) inside the first mold3and second mold4is properly adjusted by a not-shown first positive pressure applying means. This first positive pressure applying means allows for transfer of the parison S to the molding portions3a,4a.

The first mold3is constructed to separate, and includes a main body portion3band a separable portion3cthat can be detached from the main body portion3b. Similarly, the second mold4is constructed to separate, and includes a main body portion4band a separable portion4cthat can be detached from the main body portion4b. The separable portions3c,4care provided with recesses3d,4dformed therein, which correspond to the shapes of both ends of the internal component6, and these recesses3d,4daccommodate a part of the internal component6. The recesses3d,4dhere have a cylindrical shape. Additionally, in the bottom portions3f,4fof the recesses3d,4d, multiple air holes3g,4gare formed to send air into the recesses3d,4d, respectively, and the air pressure (blow pressure) inside the recesses3d,4dis properly adjusted by a not-shown second positive pressure applying means.

The elevator5is a moving means for moving the internal component6to its installation position. The installation position here is inside the cylindrical parison S, and is between the separable portions3c,4c.

Next, the operation of the fuel tank manufacturing device1will be described. Before explaining the entire process of manufacturing the fuel tank T (seeFIG.1) by the fuel tank manufacturing device1, the transfer status around the end portions of the internal component6will be described.

<Transfer Status Around End Portions of Internal Component>

In reference toFIGS.6and7(andFIGS.1to4as appropriate), the transfer status of the parison S around the end portions of the internal component6during molding will be described. Note that here, the first mold3will be described because the second mold4is similar to the first mold3. The internal component6shown inFIGS.6and7shows cross-sections cut at the A-A position inFIG.2.

In the fuel tank manufacturing process, as shown inFIG.6, by moving the first mold3in the arrow direction and clamping the parison S, the neck portion6cand head portion6dof the internal component6are pushed into the recess3dtogether with the parison S.

As shown inFIG.7, when the shoulder portion6bcontacts the parison S to cover the opening of the recess3d, and the neck portion6cand head portion6dare completely pushed into (housed in) the recess3d, a positive pressure P1(first positive pressure) is generated inside the parison S by sending air into the first mold3, transferring the parison S to the first mold3. In addition, by sending air into the recess3dthrough the air holes3gformed in the recess3d, a positive pressure P2(second positive pressure) is generated inside the recess3dto allow the parison S to enter the gap6jbetween the shoulder portion6band the head portion6dfor transfer. The air in the gap6jis discharged from the communication portions6mformed in the neck portion6cthrough the cutout portion6kto the torso portion6a.

Next, the overall process of the fuel tank manufacturing device1will be described.

<Parison Injection Process>

As shown inFIG.8A, with the first mold3and second mold4opened, the die2injects a cylindrical parison S therebetween.

<Internal Component Insertion Process>

Next, as shown inFIG.8A, the elevator5rises with the internal component6held, and moves the internal component6to the attachment position. Here, the attachment position is inside the parison S and between the separable portions3c,4c.

<Internal Component Temporary Setting Process>

Next, as shown inFIG.8C, the separable portions3c,4cof the first mold3and second mold4move in directions facing each other to hold the internal component6by sandwiching the component6from both ends. Then, the elevator5descends with the internal component6released and retreats to the initial position. The initial position of the elevator5may be any position that does not interfere when the main body portions3b,4bof the first mold3and second mold4are closed.

<Mold Closing Process>

Next, as shown inFIG.9A, the main body portions3b,4bof the first mold3and second mold4move in directions facing each other, and the first mold3and second mold4are clamped.

<Blow Molding Process>

Next, as shown inFIG.9B, the not-shown first positive pressure applying means applies a positive pressure P1(first positive pressure) to the inside of the parison S in the first mold3and second mold4. As a result, the parison S is pressed against and transferred to the molding portions3a,4aof the first mold3and second mold4. Also, the not-shown second positive pressure applying means applies a positive pressure P2(second positive pressure) to the outside of the parison S in the recesses3d,4d(seeFIG.7) of the first mold3and second mold4. As a result, the parison S is shaped along the neck portion6cof the internal component6(seeFIG.7). Note that there is no particular limitation on the method and order of applying the positive pressures P1and P2. It is preferable that the positive pressure P2is set higher than the positive pressure P1.

<Parison Cooling Process>

Next, as shown inFIG.9C, cooling air C is circulated inside the first mold3and second mold4using not-shown cooling means. As a result, the parison S is cooled and cured.

<Mold Opening Process>

Next, as shown inFIG.9D, the first mold3and second mold4are opened and the molded product U is taken out. Then, by cutting off unnecessary burrs formed at both ends, the fuel tank T (seeFIG.1) is completed.

According to the embodiment described above, the internal component6attached to the tank main body Ta includes a head portion6d, a neck portion6c, and a shoulder portion6b, and the head portion6dhas a rotation-stopping shape to stop the rotation of the internal component6. Therefore, compared to when the head portion6dis circular, rotation of the internal component6can be made more difficult, suppressing rotation of the internal component6after parison molding.

Further, since the head portion6dis an elliptical shape, it is easy to design and manufacture the rotation-stopping shape, and rotation of the internal component6can be suppressed simply and suitably. Note that in the present embodiment, the shoulder portion6band neck portion6care circular and the head portion6dis elliptical or substantially elliptical. However, the shoulder portion6b, neck portion6cand head portion6dmay all be made elliptical or substantially elliptical so that they are similar. This improves the moldability of the internal component6.

Second Embodiment

Next, an internal component60according to a second embodiment of the present invention will be described. As shown inFIG.10, the internal component60includes a cylindrical torso portion60a, shoulder portions60b,60bformed at both left and right ends of the torso portion60a, neck portions60c,60cformed at the left and right outsides of the shoulder portions60b,60b, and head portions60d,60d. The structure of the internal component60is symmetrical in left and right (up and down on the paper).

In the second embodiment, the rotation-stopping shape is such that the head portion60dhas a broad bean shape. Further, corresponding to the shape of the head portion60d, the neck portion60cand the shoulder portion60balso have a broad bean shape, and these three portions are similar. As shown inFIG.11, the head portion60dincludes an arcuate first opposing side60p, an arcuate second opposing side60q, a connecting piece60rconnecting one end side of the first opposing side60pand second opposing side60q, and a connecting piece60rconnecting the other end side of the first opposing side60pand second opposing side60q. The first opposing side60pand second opposing side60qare formed to be convex in the same direction (rear side). The connecting pieces60r,60rare formed to be convex in directions away from each other.

As shown inFIG.11, multiple cutout portions60kare formed in the head portion60dand neck portion60c. The cutout portions60kopen at the end surface of the head portion60dand are hollow from the head portion60dto the neck portion60c. As in the second embodiment, the rotation-stopping shape of the head portion60dmay be a broad bean shape. The other configurations and effects of the second embodiment are the same as those of the first embodiment, and thus description thereof is omitted.

The embodiments of the invention have been described, but design changes are possible within the scope not departing from the gist of the present invention. Although the parison was made to wrap around the neck portion by positive pressure from outside the parison (blow molding) to fix the internal component, other molding methods may be used for molding.

REFERENCE SIGNS LIST

6,60internal component6atorso portion6bshoulder portion6cneck portion6dhead portionS parisonT fuel tankTa tank main body