JP2000118250A - Fuel tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve a concentration of stress acting on walls at deforming time of a fuel storage chamber by arranging a stress absorbing means on the periphery of the prescribed part of the walls having the prescribed part having rigidity higher than the walls. SOLUTION: A projecting bead 76 for surrounding the vicinity of a fuel pipe 60 corresponding to a stress absorbing means to a lower wall 8 is integrally molded on the lower wall 8 having the fuel pipe 60 having rigidity higher than the lower wall 8. A projecting bead 75 for surrounding the vicinity of a cutoff valve 12 corresponding to a stress absorbing means to an upper wall 7 is integrally formed on the upper wall 7 having the cutoff valve 12 having rigidity higher than the upper wall 7. According to this constitution, even when the upper wall 7 and the lower wall 8 are curved and deformed, since the beads 75, 76 are respectively arranged on the periphery of the cutoff valve 12 of the upper wall 7 and the periphery of the fuel pipe 60 of the lower wall 8, a stress concentration to the periphery of the cutoff valve 12 of the upper wall 7 and the periphery of the fuel pipe 60 of the lower wall 8 can be respectively relieved to thereby eliminate breaking of the upper wall 7 and the lower wall 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank for storing fuel.

[0002]

2. Description of the Related Art When there is a space above a fuel level in a fuel tank, fuel vapor is generated, and this fuel vapor may be released to the atmosphere. Therefore, a fuel storage chamber for storing fuel is formed of a stretchable surrounding film, and the surrounding film is expanded and contracted in accordance with the amount of fuel in the fuel storage room, and fuel vapor is generated above the fuel level in the fuel storage room. A fuel tank which is not used is disclosed in, for example, JP-A-8-170568. Specifically, the surrounding film includes an upper wall and a lower wall, and a bellows-like side wall connecting the upper wall and the lower wall to each other. The lower wall of the surrounding film is a flat bottom wall of the housing. Attached to. Then, the upper wall of the surrounding film moves up and down in the housing in accordance with the amount of fuel in the fuel storage chamber, and the side wall expands and contracts as the upper wall moves up and down. Accordingly, the volume of the fuel storage chamber increases and decreases.

[0003]

However, in the above-described fuel tank, since the lower wall constituting the fuel storage chamber is fixed to the bottom wall of the housing, the lower wall has a smaller amount of fuel stored in the fuel storage chamber. It will not be displaced or deformed accordingly. For this reason, the amount of fuel that can be stored in the fuel storage chamber becomes maximum when the bellows-like side wall extends to the maximum, and the fuel storage amount cannot be further increased with this structure.

[0004] Therefore, Japanese Patent Application No. Hei.
No. 0-53739 discloses that the lower wall and the upper wall increase the volume of the fuel storage chamber in accordance with the increase in the amount of fuel stored in the fuel storage chamber in order to increase the amount of fuel that can be stored in the fuel storage chamber. That is, there is disclosed a fuel tank having a deformed wall in which a lower wall is deformed downward and an upper wall is deformed upward. Further, in such a fuel tank, predetermined parts such as a valve (valve) and a fuel passage for supplying / discharging fuel are connected to the upper wall and the lower wall by welding or integral molding.

Here, since the upper wall and the lower wall are deformable walls, the rigidity of a predetermined portion such as a valve or a fuel passage is higher than the rigidity thereof. When such rigid parts such as valves and fuel passages are connected to the upper and lower walls by welding or integral molding, stress concentrates around predetermined parts of the upper and lower walls when the fuel storage chamber is deformed. However, the upper wall and the lower wall may be locally bent.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and in a fuel tank having a fuel storage chamber that can be deformed in accordance with the amount of fuel to be stored, when a fuel storage chamber is deformed, It is an object of the present invention to provide a fuel tank capable of reducing stress concentration acting on a wall having a portion and preventing breakage of the wall.

[0007]

According to a first aspect of the present invention, there is provided a fuel tank having a fuel storage chamber which can be deformed in accordance with an amount of fuel to be stored. A predetermined portion having a higher rigidity than the wall is provided, and stress absorbing means capable of reducing concentration of stress acting on the wall when the fuel storage chamber is deformed is provided around the predetermined portion of the wall. .

According to the fuel tank according to the first aspect of the present invention, when the fuel storage chamber is deformed, the wall having the predetermined portion having a higher rigidity than the wall is provided around the predetermined portion by the stress absorbing means. The concentration of the acting stress is reduced.

Here, the stress absorbing means is, specifically, a concave bead, a convex bead, or an uneven bead formed on the wall as in the second invention.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a fuel tank according to the present invention will be described below with reference to the accompanying drawings. In each of the drawings, the same elements are denoted by the same reference numerals, and redundant description will be omitted.

The fuel tank of the present invention is used, for example, as a tank for storing fuel to be supplied to an internal combustion engine. Of course, it can also be used simply as a tank for storing fuel.

FIG. 1 is a partial sectional view showing a fuel storage device provided with a fuel tank according to a first embodiment. The fuel storage device 1 includes a housing (also referred to as a tank shell) 4 that forms an outer shell of the fuel storage device 1. The housing 4 is formed of a rigid member such as a metal or a synthetic resin, and includes an upper part 2 and a lower part 3 which are vertically divided. The upper part 2 has an upwardly curved shape and the lower part 3 has a downwardly curved shape.
Are flange portions 2a, 3 formed on the entire periphery of each peripheral portion.
a is hermetically connected to each other.

Upper part 2 and lower part 3 of housing 4
In the interior space defined by
2 (see FIG. 2), the inner space inside the housing 4 is divided by the fuel storage chamber 5 inside the separating wall 6.
And the upper and lower space portions 61a and 61b outside the separation wall 6. The separation wall 6 and the fuel storage chamber 5
Constitutes a fuel tank 70.

As shown in FIG. 2, the separation wall 6 constituting the fuel tank 70 has a substantially rectangular parallelepiped shape in its basic shape, and has a pair of substantially rectangular upper and lower walls 7 and 8 which are vertically opposed to each other. , Four substantially rectangular side walls (peripheral walls) 9 that connect (close) the corresponding sides of the upper wall 7 and the lower wall 8
a to 9d. These side walls 9a to 9d are connected at both ends to the ends of other adjacent side walls, and connecting portions 9e to 9h are formed between the side walls 9a to 9d, respectively.

The upper wall 7, the lower wall 8, and the side walls 9a to 9d
Is formed in a multilayer structure in which both surfaces of a flat core portion made of, for example, a copolymer resin of ethylene and vinyl or nylon are covered with a skin portion made of high-density polyethylene. It is rigid and deformable.

The area of the upper wall 7 or the lower wall 8 is larger than the area of one side wall, and the rigidity of the upper wall 7 and the lower wall 8 is
It is smaller than the side walls 9a to 9d.

Here, the upper wall 7 and the lower wall 8 are not limited to rectangular walls, but may be a pair of polygonal walls. Therefore,
The upper wall 7 and the lower wall 8 correspond to polygonal walls, and the side walls 9a to 9d
Corresponds to a connecting wall connecting the upper wall 7 and the lower wall 8. The shapes of the upper wall 7, the lower wall 8, and the side walls 9a to 9d are appropriately selected according to the shape of the space in which the fuel tank 70 is to be installed.

As described above, the fuel storage chamber 5 having a substantially rectangular parallelepiped shape in the basic shape of the separation wall 6 is defined inside the separation wall 6, and the fuel is supplied to the fuel storage chamber 5.
When the amount of fuel in the fuel storage chamber 5 exceeds a fuel amount capable of maintaining a rectangular parallelepiped shape (hereinafter referred to as a predetermined amount), as shown in FIGS. 3 and 4, the upper wall 7 and the lower wall 8 separate from each other and move outward. The side walls 9a to 9d are curved and deformed so as to bulge toward each other and to be depressed inward as they approach each other.

That is, when the amount of fuel in the fuel storage chamber 5 exceeds a predetermined amount, the upper wall 7 bends vertically upward and the lower wall 8 bends vertically downward. 9a to 9d are curved and deformed so as to warp in the horizontal direction and inward. Thus, the amount of fuel that can be stored in the fuel storage chamber 5 gradually increases.

On the other hand, when the fuel in the fuel storage chamber 5 is discharged,
When the fuel amount in the fuel storage chamber 5 decreases below a predetermined amount, as shown in FIGS. 5 and 6, the upper wall 7 and the lower wall 8 are curved and deformed so as to be closer to each other and concave inward, and the side walls 9a to 9 are formed.
d approach each other and bend and deform inwardly.

That is, when the amount of fuel in the fuel storage chamber 5 decreases below a predetermined amount, the upper wall 7 bends downwardly and the lower wall 8 bends upwardly.
a to 9d are curved and deformed such that they warp in the horizontal direction and inward. Then, as shown in FIG. 6, the upper wall 7 and the lower wall 8 are recessed so as to be in close contact with each other. Thus, the amount of fuel that can be stored in the fuel storage chamber 5 gradually decreases.

The deformation of the upper wall 7 and the lower wall 8 is larger than the deformation of the side walls 9a to 9d. Therefore, the upper wall 7 and the lower wall 8 correspond to large deformation surfaces, and the side walls 9a to 9d correspond to small deformation surfaces.

Referring to FIG. 1 again, a fuel pipe (predetermined portion) 60 for supplying or discharging fuel to or from the fuel storage chamber 5 is connected to substantially the center of the lower wall 8 constituting the separation wall 6.
As shown in FIGS. 1 and 10, the fuel pipe 60 is formed integrally with the separation wall 6, and its rigidity is higher than that of the lower wall 8.

The lower wall 8 having the fuel pipe 60 has a structure shown in FIG.
As shown in FIG. 10, a convex bead 76 surrounding the vicinity of the fuel pipe 60 is integrally formed (the overall shape is similar to a bead 75 described later in FIG. 9).
As shown in FIG. 10 in particular, the bead 76 has the upper wall 7 bent downward and the lower wall 8 bent upward, so that the upper wall 7 and the lower wall 8 contact each other at substantially the center and are in close contact with each other. Is provided on the lower surface side of the close contact portion of the lower wall 8 when. This bead 76 relieves stress concentrated around the fuel pipe 60 on the lower wall 8 when the lower wall 8 is bent and deformed.
It corresponds to a stress absorbing means for the lower wall 8.

As shown in FIG. 1, the fuel pipe 60 branches below the lower wall 8 into a fuel supply pipe 10 and a fuel introduction pipe 20 connected to an auxiliary fuel tank 14 described later. You. Then, the fuel introduced from a fuel inlet (not shown) is supplied to the fuel storage chamber 5 through the fuel supply pipe 10 and the fuel pipe 60, and is supplied into the auxiliary fuel tank 14 through the fuel introduction pipe 20. Is done. In addition, the fuel storage room 5
When the fuel is discharged, the fuel pipe 60, the fuel introduction pipe 20
Is sucked into the auxiliary fuel tank 14 through the

The fuel supply pipe 10 and the fuel introduction pipe 2
Reference numeral 0 indicates that at the connection portion with the fuel pipe 60, the pipe wall has a bellows shape, and is capable of being expanded and contracted and bendable, and allows the lower wall 8 to bend and deform. In the present embodiment, the fuel introduction tube 20 has a bellows shape over the entire length.

A cutoff valve (predetermined portion) 12 is welded to the upper wall 7 constituting the separation wall 6 at substantially the center thereof by welding. The shutoff valve 12 shuts off the inside of the fuel storage chamber 5 from the outside when the fuel level of the fuel storage chamber 5 reaches the shutoff valve 12, and its rigidity is higher than the rigidity of the upper wall 7.

As shown in FIGS. 1, 9 and 10, a convex bead 75 surrounding the vicinity of the shut-off valve 12 is formed integrally with the upper wall 7 having the shut-off valve 12. As shown in FIG. 10 in particular, the bead 75 has the upper wall 7 bent downward and the lower wall 8 bent upward,
The upper wall 7 and the lower wall 8 are provided on the upper surface side of the contact portion of the upper wall 7 when the upper wall 7 and the lower wall 8 contact each other at substantially the center and come into close contact. The bead 75 relieves stress concentrated around the shutoff valve 12 on the upper wall 7 when the upper wall 7 is bent and deformed, and corresponds to a stress absorbing means for the upper wall 7.

In FIGS. 2 to 6, components constituting the separation wall 6, such as the beads 75 and 76, the fuel pipe 60, the shutoff valve 12, and the like are omitted in order to facilitate the understanding of the drawings.

The shutoff valve 12 is connected to an evaporative fuel discharge pipe 11 for discharging the gas in the fuel storage chamber 5, particularly the evaporative fuel, to the outside of the fuel storage chamber 5. The fuel vapor discharge pipe 11 has flexibility and allows the upper wall 7 to bend and deform.

The fuel vapor discharge pipe 11 is connected to the check valve 1
3. It is connected to an intake passage (not shown) of the internal combustion engine via a charcoal canister (not shown) for temporarily absorbing fuel vapor. The fuel vapor adsorbed by the charcoal canister is purged into the intake passage according to the operating state of the internal combustion engine, and is burned by the engine.

The check valve 13 is provided with the check valve 13.
The pressure in the fuel vapor discharge pipe 11 between the valve and the shut-off valve 12 is
The valve opens when the pressure exceeds a preset positive pressure, and closes when the pressure becomes lower than the preset positive pressure. By the operation of the check valve 13, the gas is prevented from entering the fuel storage chamber 5 after the shut-off valve 12 is once shut off.

Further, a fuel gauge 71 is provided on the inner wall surface of the upper portion 2 of the housing 4 for detecting a displacement position or a moving amount of the upper wall 7 in a vertical direction and calculating a fuel amount of the fuel storage chamber 5. I have. The fuel gauge 71 is a pendulum type gauge, and calculates the fuel amount from the displacement angle of the pendulum.

On the lower portion 3 of the housing 4 and below the fuel pipe 60 of the lower wall 8 on the side of the side wall 9c, an auxiliary fuel tank 14 for temporarily storing fuel in the fuel storage chamber 5 is provided. Is arranged. A fuel pump 16 for sending the fuel in the auxiliary fuel tank 14 through a fuel feed pipe 15 to a fuel injection valve (not shown) of the internal combustion engine is arranged in the auxiliary fuel tank 14. The fuel pump 16 sucks the fuel through a filter 17 for filtering dust and the like contained in the fuel, regulates the pressure to a predetermined fuel pressure, and sends the fuel to a fuel injection valve.

On the lower wall 50 of the auxiliary fuel tank 14, there is provided a partition wall 18 extending substantially vertically upward.
As shown in FIG. 7, the dividing wall 18
And an accommodation chamber 19 that is arranged to surround the filter 17 and accommodates the fuel pump 16 and the filter 17. The auxiliary fuel tank 14 is inclined so that the fuel level in the auxiliary fuel tank 14 is inclined. Sometimes, the fuel around the filter 17 is prevented from being depleted. Therefore, the separation wall 18 corresponds to a fuel depletion prevention unit.

Also, as shown in FIG. 1, the upper surface of the upper wall 52 of the auxiliary fuel tank 14 and the lower portion 3 of the housing 4
The upper surface of the lower portion 3a of the lower wall 8 on the side of the side wall 9a from the fuel pipe 60 (hereinafter simply referred to as a predetermined portion of the lower portion 3) is formed when the lower wall 8 of the separation wall 6 is curved downward. The lower wall 8
And the lower surface of the upper part 2 of the housing 4
It matches the shape of the upper wall 7 when the upper wall 7 of the separation wall 6 is curved upward.

Accordingly, the lower wall 8 is bent downward and deformed, and the upper wall 52 of the auxiliary fuel tank 14 and the lower portion 3 of the housing 4 are formed.
The upper wall 52 and the predetermined portion 3a of the lower portion 3 suppress the further downward bending deformation of the lower wall 8 when the upper wall 52 and the lower portion 3 abut against the upper surface of the predetermined portion 3a. When the upper wall 7 is bent upward and comes into contact with the lower surface of the upper part 2 of the housing 4, the upper part 2 moves upward beyond the upper wall 7. Of the upper wall 7 is restricted to a predetermined size.

Accordingly, the lower wall 8 and the upper wall 7 of the separation wall 6 are
The upper wall 52 of the auxiliary fuel tank 14, the predetermined portion 3a of the lower portion 3 of the housing 4, and the upper portion 2 of the housing 4 prevent the upper wall 7 from being extremely bent and deformed beyond a preset allowable value. And the lower wall 8 is protected at the time of bending deformation. In addition, the shapes of the upper wall 52 of the auxiliary fuel tank 14 and the predetermined portion 3a of the lower part 3 of the housing 4 match the downward curved shape of the lower wall 8, and the upper part 2 of the housing 4
The upper wall 7 and the lower wall 8 are further protected during the bending deformation because the shape of the upper wall 7 matches the upward curved shape of the upper wall 7. The protection of the upper wall 7 and the lower wall 8 in this way prevents the fuel tank 70 from being damaged.

As for the fuel supply to the fuel storage chamber 5 through the fuel supply pipe 10, the lower wall 8 of the separation wall 6 is formed by the upper wall 52 of the auxiliary fuel tank 14 and the lower part 3 of the housing 4. The upper wall 7 of the separation wall 6 contacts the upper surface of the predetermined portion 3a.
Stops when it contacts the lower surface of the upper part 2 of the housing 4. That is, the predetermined portion 3 of the upper wall 52 of the auxiliary fuel tank 14 and the lower portion 3 of the housing 4
a, the maximum storage amount of fuel in the fuel storage chamber 5 is determined by the upper part 2 of the housing 4.

It is to be noted that the portion of the upper portion 2 of the housing 4 opposed to the bead 75, the portion of the lower portion 3 of the housing 4 and the portion of the upper wall 52 of the auxiliary fuel tank 14 opposed to the bead 76 increase the fuel. The bead at time 75,
It is more preferable to provide a groove for avoiding the interference with the groove 76.

As shown in FIGS. 1 and 8, the height of the side walls 9 a to 9 d of the separation wall 6 is set inside the entire periphery of the housing periphery connecting the upper part 2 and the lower part 3 of the housing 4. A gap 21 having substantially the same height is formed by the upper part 2 and the lower part 3. In the space 21, the side walls 9a to 9d and the connecting portions 22 of the lower walls 7, 8 connected to the side walls 9a to 9d are accommodated. In addition, the connecting portion 22 of the lower walls 7, 8 is regarded as a part of the side wall,
Hereinafter, the connecting portion 22 of the upper and lower walls 7, 8 and the side walls 9a to
9d together is referred to as a side wall equivalent portion 62, which corresponds to the peripheral portion of the separation wall 6 (fuel tank 70).

In this manner, the separation wall 6 is formed as a side wall corresponding portion 62.
Is sandwiched between the upper part 2 and the lower part 3 of the housing 4 and supported so as to be slidable in the horizontal direction with respect to the housing 4. That is, the separation wall 6 is formed by the housing peripheral edge connecting the upper part 2 and the lower part 3 of the housing 4.
The holding portion 23 is configured to hold the side wall equivalent portion 62 slidably in the horizontal direction (see FIG. 8). This holding portion 23
Correspond to a support member that supports the separation wall 6.

According to the fuel tank 70 constructed as described above, the fuel is supplied via the fuel supply pipe 10 into the separation wall 6 whose basic shape is the substantially rectangular parallelepiped shape shown in FIG. When the fuel amount of No. 5 exceeds the predetermined amount described above, FIG.
As shown in (1), the upper wall 7 is curved and deformed upward, the lower wall 8 is curved and deformed downward, and the side walls 9a to 9d are curved and deformed inward. These curvatures are not suppressed by the holding portion (support member) 23 that supports the fuel tank 70,
It gradually increases as the fuel amount increases, and the fuel storage chamber 5
Is increased, and a maximum amount of fuel is stored in the fuel storage chamber 5. At this time, the auxiliary fuel tank 14 is also filled with fuel.

As described above, in the present embodiment, a larger amount of fuel is provided as compared with a fuel tank in which the upper wall 7 is not bent upward and the lower wall 8 is not bent downward as the fuel amount increases. The amount is stored in the fuel storage chamber 5. Therefore, the amount of fuel that can be stored in the fuel storage chamber 5 can be maintained at a maximum.

On the other hand, when the fuel is discharged, the fuel pump 1
6, the fuel in the fuel storage chamber 5 is supplied to the fuel pipe 60,
The fuel is delivered to the fuel injection valve of the internal combustion engine via the fuel introduction pipe 20, the filter 17, and the fuel delivery pipe 15. With the decrease in the amount of fuel in the fuel storage chamber 5, the upward bending of the upper wall 7, the downward bending of the lower wall 8, and the inward bending of the side walls 9a to 9d are gradually eliminated. When the fuel amount in the fuel storage chamber 5 decreases to a predetermined amount, the separation wall 6 returns to the substantially rectangular parallelepiped shape shown in FIG.

Further, when the fuel is discharged from the fuel storage chamber 5 and the fuel amount in the fuel storage chamber 5 becomes smaller than a predetermined amount, as shown in FIG. 5, the upper wall 7 is bent downward by the negative pressure due to the suction. At the same time, the lower wall 8 bends upwardly, and the side walls 9a to 9d bend inwardly. These curvatures are not suppressed by the holding portion 23 supporting the fuel tank 70, but gradually increase as the fuel amount decreases. As shown in FIG. 6, the upper wall 7 and the lower wall 8 The contact is made at the approximate center, and the contact state is established, and further progress of the curve deformation is suppressed.

As described above, in this embodiment, the upper wall 7 and the lower wall 8 are reduced by the curvature in comparison with the fuel tank in which the upper wall 7 and the lower wall 8 are not curved and deformed downward with the decrease in the fuel amount. The volume of the space portion of the fuel storage chamber 5 is reduced by an amount corresponding to the volume of the fuel storage chamber 5 thus set. Therefore, the amount of fuel vapor is significantly reduced.

The upper wall 7 is connected to a shut-off valve 12 having a higher rigidity than the upper wall 7, and the lower wall 8 is connected to a fuel pipe 60 having a higher rigidity than the lower wall 8. 7
And when the lower wall 8 is bent and deformed,
The stress concentrates around the circumference 2 and the stress concentrates around the fuel pipe 60 on the lower wall 8, and the upper wall 7 and the lower wall 8 may be locally bent.

However, in this embodiment, as shown in FIGS. 1, 9 and 10, the shut-off valve 1 of the upper wall 7 is provided.
2 around the fuel pipe 60 around the lower wall 8 and beads 75 and 76
Are provided, the beads 75 and 76 alleviate the stress concentration. For this reason, the upper wall 7 and the lower wall 8 do not break. In addition, especially when the fuel is low, the upper wall 7 and the lower wall 8 are in close contact with each other at substantially the center thereof, and stress is particularly concentrated on the close contact portion. In this embodiment, the beads 75 and 76 are used. But Figure 1
As shown in FIG. 0, since it is provided at the contact portion, stress concentration at the contact portion is reduced, and the upper wall 7 and the lower wall 8 are provided.
Is prevented from being broken.

In this embodiment, the beads 75, 76
Is a convex bead, but may be a concave bead or a concave and convex bead.

FIGS. 11A and 11B show a fuel tank according to a second embodiment, wherein FIG. 11A is a plan view and FIG. 11B is a bottom view.

The fuel tank 77 of the second embodiment is
The difference from the fuel tank 70 of the embodiment is that, as shown in FIG. 11A, a bead 75a surrounding the bead 75 and a bead 75b surrounding the bead 75a are provided on the upper wall 7.
11B, a bead 76a surrounding the bead 76 and a bead 76b surrounding the bead 76a are further provided on the lower wall 8 as shown in FIG. 11B.

That is, the beads surrounding the shut-off valve 12 on the upper wall 7 are multi-stage beads 75, 75a and 75b, and the beads surrounding the fuel pipe 60 on the lower wall 8 are multi-stage beads 76, 76a and 76b. .

According to the fuel tank 77 of the second embodiment configured as described above, the added beads 75 on the upper wall 7 side are provided.
a, 75b, beads 76a, 76b on the lower wall 8 side,
Since the stress concentration on the upper wall 7 and the lower wall 8 is gradually alleviated as compared with the first embodiment, breakage of the upper wall 7 and the lower wall 8 is further prevented. Note that the width, shape, and the like of each bead may be appropriately changed to gradually reduce stress concentration.

FIG. 12 is a plan view showing a fuel tank according to the third embodiment, and FIG. 13 is a front view of the fuel tank shown in FIG.

In the fuel tank 80 of the third embodiment, uneven beads 81 and 8 surrounding the shut-off valve 12 are provided.
2, 83 are provided on the upper wall 7 in this order from the vicinity of the shut-off valve 12 toward the connection with the side walls 9a to 9d, and the uneven beads 91, 9 surrounding the fuel pipe 60 are provided.
Reference numerals 2 and 93 are provided on the lower wall 8 in this order from the vicinity of the fuel pipe 60 to the connection portion with the side walls 9a to 9d.

The beads 81 to 83 are formed integrally with the upper wall 7, and the beads 91 to 93 are formed integrally with the lower wall 8. The bead 81 near the shutoff valve 12 and the bead 91 near the fuel pipe 60 are beads 75 and 76 of the first embodiment, respectively.
And are located in roughly the same position. Also, the outer bead 83,
Reference numerals 93 are respectively located near the connection portions with the side walls 9a to 9d. As shown in FIG. 12, the beads 81 to 83 of the upper wall 7 and the beads 91 to 93 of the lower wall 8 are formed so as to exclude the positions of the diagonal lines L1 and L2 of the upper wall 7 and the lower wall 8 which are substantially rectangular. Each is formed. That is, the beads 81 to 83 of the upper wall 7 and the beads 91 to 93 of the lower wall 8 are
Each is a discontinuous bead lacking the positions L1, L2. In addition, in FIG. 13, in consideration of the easiness of understanding of the drawing, beads in the near-side and back-side areas sandwiching the shutoff valve 12 and the fuel pipe 60 in the substantially triangular range surrounded by the diagonal lines L1 and L2. Reference numerals 81 to 83 and 91 to 93 are omitted, and only beads 81 to 83 and 91 to 93 in the range on the left and right sides are illustrated.

As described above, the beads 81 to 83 of the upper wall 7 and the beads 91 to 93 of the lower wall 8 are discontinuous beads lacking the positions of the diagonal lines L1 and L2. The bead 81 in the vicinity and the bead 91 in the vicinity of the fuel pipe 60 in the lower wall 8 are extended to the diagonal lines L1 and L2 of the upper wall 7 and the lower wall 8, respectively. Of the upper wall 7 and the beads 92, 9 of the lower wall 8 are not hindered.
3, that is, the bead at a position relatively distant from the shut-off valve 12 and the fuel pipe 60 is connected to the diagonal lines L1, L2 of the upper wall 7 and the lower wall 8.
, The beads are extended to the respective positions, and when the upper wall 7 and the lower wall 8 are curved and deformed, the portions of the upper wall 7 and the lower wall 8 at the positions of the diagonal lines L1 and L2 protrude, and the portions are bent. This is because there is a fear.

The beads 81 to 83 and beads 91 to 93 having the above shapes are used when the upper wall 7 and the lower wall 8 are curved and deformed.
The stress concentrated around the shutoff valve 12 on the upper wall 7 and the stress concentrated around the fuel pipe 60 on the lower wall 8 are alleviated, and the beads 81 to 83 correspond to stress absorbing means for the upper wall 7. Reference numerals 91 to 93 correspond to stress absorbing means for the lower wall 8. Also, the side walls 9a to 9d of the upper wall 7 and the lower wall 8
The beads 83 and 93 in the vicinity of the connecting portion between the upper wall 7 and the lower wall 8 relieve the stress acting on the connecting portion between the upper wall 7, the lower wall 8 and the side walls 9a to 9d when the upper wall 7 and the lower wall 8 are curved and deformed. Is provided for other purposes.

According to the fuel tank 80 of the third embodiment configured as described above, the beads 81 to 83 of the upper wall 7 and the beads 91 to 93 of the lower wall 8 lack the positions of the diagonal lines L1 and L2. Since each of the beads is a continuous bead, the upper wall 7 and the lower wall 8 are appropriately curved and deformed according to the amount of fuel.

At this time, the beads 81 to 83 provided around the shut-off valve 12 on the upper wall 7 and the beads 91 to 93 provided around the fuel pipe 60 on the lower wall 8 concentrate the stress acting on the upper wall 7. The stress concentration acting on the lower wall 8 is alleviated,
As in the first embodiment, breakage of the upper wall 7 and the lower wall 8 is prevented. In addition, the stress acting on the connecting portions is reduced by the beads 83 and 93 near the connecting portions of the upper wall 7 and the lower wall 8 with the side walls 9a to 9d. Therefore, the connecting portion is not twisted, and the side walls 9a to 9d are prevented from being broken.

In this embodiment, the uneven beads 82 and 83 of the upper wall 7 and the uneven beads 92 and 83 of the lower wall 8 are provided.
The portion 93 allows the outer peripheral portion of the upper wall 7 and the lower wall 8 to be more deformable than the first embodiment compared to the first embodiment. For this reason, as shown by the phantom line in FIG. 13, when the fuel increases, the upper wall 7 and the lower wall 8 have their outer peripheral sides curved and deformed larger and lower than in the first embodiment, respectively. Upper wall 7 and lower wall 8 due to bending deformation
Is flattened as compared with the first embodiment.

Accordingly, stress concentration near the shutoff valve 12 on the upper wall 7 and near the fuel pipe 60 on the lower wall 8 is reduced as compared with the first embodiment, and the volume of the fuel storage chamber 5 is increased compared to the first embodiment. As a result, the fuel storage amount is increased.

Although the present invention has been specifically described based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, the holding portion 23 of the housing 4 Although the whole side wall equivalent portion 62 is configured to be supported, four corners of the side wall equivalent portion 62 (four corners of the fuel tanks 70, 77, and 80).
It is good also as composition which supports only. Even with such a configuration, the corner portion has the upper wall 7, the lower wall 8, and the connecting portions 9e to 9h connecting the adjacent side walls, and has the highest rigidity as compared with the other portions and almost no deformation. Therefore, the deformation of the side walls 9a to 9d and the upper wall 7 and the lower wall 8 is not suppressed.
a to 9d, the upper wall 7, and the lower wall 8 can be curved and deformed in the same manner as in the above embodiment. Further, since the corners have high rigidity as described above, the fuel tanks 70, 77, and 80 can be favorably supported even with a configuration that supports only the corners. Furthermore, it is needless to say that since the configuration supports only the corners as described above, the configuration can be simplified as compared with the above embodiment in which the entire side wall corresponding portion 62 is supported.

It should be noted that the present invention is composed of the upper wall 7 and the lower wall 8 which form a polygon and oppose each other, and the side walls 9a to 9d which close the upper wall 7 and the lower wall 8 as described above. It does not apply only to fuel tanks 70, 77, 80,
The present invention is applicable to all fuel tanks having a fuel storage chamber that can be deformed according to the amount of fuel stored.

[0066]

According to the fuel tank of the present invention, the stress absorbing means provided around the predetermined portion of the wall having the predetermined portion having higher rigidity than the wall reduces the concentration of the stress acting on the wall when the fuel storage chamber is deformed. In order to alleviate this, it is possible to prevent the wall from being broken. As a result, the reliability of the fuel tank can be improved.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a fuel storage device including a fuel tank according to a first embodiment.

FIG. 2 is a perspective view showing a basic shape of a fuel tank.

FIG. 3 is a perspective view showing a state of a fuel tank when the fuel is fully filled.

FIG. 4 is a sectional view taken along line XX of FIG. 3;

FIG. 5 is a perspective view showing a state of a fuel tank when a fuel becomes low.

FIG. 6 is a sectional view taken along line XX of FIG. 5;

FIG. 7 is a sectional plan view showing an auxiliary fuel tank.

FIG. 8 is a detailed sectional view showing a portion A in FIG. 1 in an enlarged manner.

FIG. 9 is a plan view of the fuel tank shown in FIG.

10 is a cross-sectional view showing a state of the fuel tank when the fuel in the fuel tank in FIG. 9 becomes low.

FIGS. 11A and 11B show a fuel tank according to a second embodiment, wherein FIG. 11A is a plan view and FIG. 11B is a bottom view.

FIG. 12 is a plan view showing a fuel tank according to a third embodiment.

FIG. 13 is a front view of the fuel tank shown in FIG.

[Explanation of symbols]

5: fuel storage chamber, 7: upper wall (wall), 8: lower wall (wall), 1
2 ... shut-off valve (predetermined part), 60 ... fuel pipe (predetermined part), 7
0, 77, 80 ... fuel tank, 75, 75a, 75b,
76, 76a, 76b, 81 to 83, 91 to 93 ... beads (stress absorbing means).

Claims (2)

[Claims] 1. A fuel tank having a fuel storage chamber that can be deformed in accordance with the amount of fuel to be stored, the fuel storage chamber comprising a deformable wall, a deformable wall having a predetermined portion having a higher rigidity than the wall, A fuel tank, comprising: a stress absorbing means capable of reducing the concentration of stress acting on the wall when the fuel storage chamber is deformed, around the predetermined portion of the wall. 2. The fuel tank according to claim 1, wherein the stress absorbing means is a concave bead, a convex bead, or an uneven bead formed on the wall.