JPH10196479A - Fuel tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a separation film from being damaged. SOLUTION: In a fuel tank provided with a separation film 5 for separating an internal space 4 of a fuel tank 1 into a combustion chamber 1 and an air chamber 6, and in which the separation film is to be vertically moved with the fuel liquid surface while being brought in close-contact with the fuel liquid surface, the separation film is formed into the corrugated sectional shape, and a reinforcing member 32 extending along the corrugated bent part 30 is attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel tank.

[0002]

2. Description of the Related Art In order to prevent the fuel vapor generated in a fuel tank from being released into the atmosphere, the fuel vapor in an upper space of the fuel tank is guided to a charcoal canister to be adsorbed on activated charcoal in the charcoal canister. Such an internal combustion engine is conventionally known. In this case, if the amount of evaporative fuel guided to the charcoal canister is large, the capacity of the charcoal canister must be increased. Therefore, in order to reduce the size of the charcoal canister, it is necessary to minimize the amount of evaporative fuel generated in the fuel tank. is there.

[0003] In order to reduce the amount of fuel vapor generated in the fuel tank, the area of the fuel level in contact with the upper space of the fuel tank may be reduced. Therefore, a plurality of substantially concentric annular folds are provided, a peripheral portion is fixed to an inner wall surface of the fuel tank via a fixing portion, and a separation membrane that separates the internal space of the fuel tank into a fuel chamber and an air chamber is provided. A vehicle fuel tank is known in which the central portion of the separation membrane moves up and down with the fuel level while being in close contact with the fuel level in the fuel chamber (see US Pat. No. 3,701,540).

[0004]

A plurality of substantially annular folds extending in the horizontal direction are formed in the separation membrane of the fuel tank. These folds are separated from each other by a predetermined distance, and the vertical cross section of the separation membrane has a waveform. When the fuel in the fuel tank swings due to the influence of acceleration / deceleration or turning of the vehicle, running on an uneven road, or the like, the separation membrane dividing the inside of the fuel tank swings and the fold expands and contracts. At this time, the valleys of the folds are depressed by the pressure of the oscillating fuel from the fuel chamber side. Also, due to variations in the thickness and cross-sectional shape of the separation membrane at the fold, and furthermore, the horizontal swing of the separation membrane causes a part of the fold to cross adjacent folds, and as a result, these folds intersect each other. I will. Due to the abnormal deformation of the separation film at such a fold, a portion where stress is locally concentrated occurs in the separation film, and there is a problem that the separation film is damaged from the stress concentration portion. An object of the present invention is to prevent damage to a separation membrane.

[0005]

According to a first aspect of the invention, there is provided a separation membrane for separating an internal space of a fuel tank into a fuel chamber and an air chamber. In a fuel tank adapted to move up and down together with the fuel liquid surface while being in close contact with the liquid surface, a reinforcing member that forms a separation membrane into a corrugated cross-sectional shape and extends along a bent portion of the corrugation, that is, a valley or a ridge. Attach. Thereby, the rigidity at the bent portion of the waveform of the separation membrane is increased.

According to a second aspect of the present invention, in order to solve the above problems, in the first aspect, adjacent reinforcing members are connected to each other by a bridging member. This increases the rigidity of the entire separation membrane and limits the relative movement between the reinforcing members. According to a third aspect of the present invention, in order to solve the above problems, in the second aspect, the bridging member is formed of an elastic material, and the reinforcing members are relatively movable with each other. Thereby, the relative movement of the reinforcing member is limited to a certain range.

[0007] According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, in the third aspect, the reinforcing member is movable in the direction of increasing or decreasing the fuel. Thereby, the reinforcing member moves up and down with the up and down movement of the fuel liquid level.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a fuel tank, particularly a vehicle fuel tank 1, includes an upper portion 2 and a lower portion 3 made of, for example, a metal or a synthetic resin material. The upper part 2 and the lower part 3 are airtightly connected to each other at the respective flange portions 2a, 3a. In the interior space 4 defined by the upper part 2 and the lower part 3, a separation membrane 5 made of a material having flexibility and fuel vapor impermeability, such as polyethylene or nylon, is disposed. The separation membrane 5 separates the internal space 4 into an upper air chamber 6 and a lower fuel chamber 7. The separation membrane 5 is air-tightly fixed to the inner wall surface of the fuel tank 1 by fixing the peripheral portion 5 a to the fixing portion 8. That is, in the present embodiment, the peripheral portion 5a of the separation membrane 5 extends over the entire circumference,
The lower portion 3 is fixed while being held between the flange portions 2a, 3a. In addition, a plurality of annular folds 5b arranged substantially concentrically are formed in advance on the separation membrane 5, and the vertical cross-sectional shape of the separation membrane 5 is a waveform. Since the separation membrane 5 can be deformed along these folds 5b, the center of the separation membrane 5 can move up and down. As a result, the center of the separation membrane 5 is moved to the fuel level in the fuel chamber 7 as described later. And can move up and down together with the fuel level. The folds 5b of the present embodiment are formed at substantially equal intervals.

Referring to FIG. 2, the air chamber 6 is communicated with the atmosphere through an air chamber pressure control valve 9 and an air cleaner 10. The air chamber pressure control valve 9 includes a positive pressure relief valve 11 and an atmospheric pressure relief valve 12 arranged in parallel with each other. The positive pressure relief valve 11 opens when the pressure in the air chamber 6 rises above a predetermined positive pressure, while the atmospheric pressure relief valve 12 opens when the pressure in the air chamber 6 exceeds atmospheric pressure. Open when it drops. Therefore, the pressure in the air chamber 6 is maintained at substantially the atmospheric pressure or higher and a positive pressure lower than the valve opening pressure of the positive pressure relief valve 11.

A fuel injection pipe 13 is hermetically connected to the fuel chamber 7. A fuel cap 14 is removably attached to the upper end opening 13a of the fuel injection pipe 13, and the fuel injection pipe 13 adjacent to the upper end opening is in contact with the outer peripheral surface of the fuel cap 14 when the fuel cap 14 is inserted. A sealing member 15 that contacts the outer peripheral surface of a fueling nozzle inserted into the fuel injection pipe 13 during refueling, and an evaporative fuel shutoff valve 17 that normally shuts off the fuel injection pipe 13 by a spring force. Be placed.

Further, referring to FIG. 2, a fuel pump chamber 18 is connected to the fuel chamber 7 and defined by a lower portion 3 protruding outside the flange portion 2a of the upper portion 2.
A fuel pump 19, a fuel pressure regulator 20, and a fuel filter 21 are arranged in the fuel pump chamber 18, and the fuel discharged from the fuel pump 19 is regulated by the fuel pressure regulator 20 before the fuel supply pipe 22. Is supplied to a fuel injection valve (not shown). When the fuel pressure regulator 20 is disposed in the fuel pump chamber 18 communicating with the fuel chamber 7 as described above, the fuel return extending from the fuel distribution pipe for distributing the fuel from the fuel supply pipe 22 to each fuel injection valve to the fuel tank 1 is provided. There is no need to provide a passage, and the fuel that is heated near the cylinder head and contains partially vaporized fuel does not return to the fuel tank 1, so that the generation of fuel vapor in the fuel tank 1 is suppressed. Further, the noise of the fuel pump 19 can be reduced by disposing the fuel pump 19 in the fuel tank 1.

A circulating pipe 23 that opens into the fuel chamber 7 is attached to the upper part 2 of the fuel tank 1. Circulation pipe 2
3 is provided for the purpose of releasing the gas above the fuel level, which becomes gradually smaller at the time of refueling, to the fuel injection pipe 13 so as to facilitate refueling, so that the outlet end 13 of the fuel injection pipe 13 is provided.
It opens above the fuel chamber 7 above the b and directly below the fixing portion 8. The upper space 18a of the fuel pump chamber 18
Is connected to the fuel injection pipe 13 above the upper end opening of the circulation pipe 23 via the evaporative fuel discharge pipe 24, and the fuel injection pipe 13 above the upper end opening of the evaporative fuel discharge pipe 24 It is connected via a pipe 25 to a charcoal canister (not shown) with activated carbon. Therefore, the evaporative fuel generated in the fuel chamber 7, the fuel injection pipe 13, and the fuel pump chamber 18 is guided to the charcoal canister through the evaporative fuel discharge pipe 24 and the evaporative fuel purge pipe 25, and is adsorbed by the activated carbon. Evaporated fuel is prevented from being released into the atmosphere. The fuel adsorbed on the activated carbon is purged into the engine intake passage according to, for example, the engine operating state (engine load).

In particular, as shown in FIG. 1, the inner wall surface of the side wall 3 b of the lower portion 3 as a whole is inclined inward from the fixing portion 8 toward the bottom wall 3 of the lower member 3. Further, a plurality of substantially annular protrusions 29 protruding inward are provided on the inner wall surface of the side wall 3b.
The inner wall surface of b has a step-like cross section. As a result, the rigidity of the lower portion 3 can be increased without adding a reinforcing member.

When refueling is to be performed, first, the fuel cap 14 is removed from the upper end opening 13a of the fuel injection pipe 13. Even when the fuel cap 14 is removed, the fuel vapor shutoff valve 17 is kept closed, so that the fuel vapor is prevented from being released to the atmosphere from the upper end opening 13a of the fuel injection pipe 13. Next, a refueling nozzle (not shown) is inserted into the upper end opening 13a of the fuel injection pipe 13,
The evaporated fuel cutoff valve 17 is opened by the tip of the refueling nozzle against the bias of the spring. In this case, since the seal members 15 and 16 are in contact with the outer peripheral surface of the refueling nozzle, the vaporized fuel is prevented from being released to the atmosphere from the upper end opening 13a of the fuel injection pipe 13 in this case as well. Next, when refueling is started, fuel is injected into the fuel chamber 7 via the fuel injection pipe 13. The fuel level rises as the fuel amount in the fuel chamber 7 increases, and the separation membrane 5 rises as the fuel level rises.
Also rises.

When the fuel level in the fuel chamber 7 increases and the fuel level rises, the separation membrane 5 is kept in close contact with the fuel level, so that the space on the fuel level is close to zero. Therefore, the amount of evaporated fuel generated in the fuel tank 1 at the time of refueling can be further reduced. On the other hand, as the separation membrane 5 rises, the volume of the air chamber 6 gradually decreases, and as a result,
The positive pressure in the air chamber 6 gradually increases. The positive pressure in the air chamber 6 urges the separation membrane 5 toward the fuel chamber 7, so that the separation membrane 5 is securely brought into close contact with the fuel liquid level. When the pressure in the air chamber 6 exceeds the opening pressure of the positive pressure relief valve 11, the positive pressure relief valve opens. Is substantially maintained at the valve opening pressure of the positive pressure relief valve 11. At this time, the pressure in the fuel chamber 7 is also substantially maintained at the valve opening pressure of the positive pressure relief valve 11.

At the time of refueling, when the fuel level in the fuel chamber 7 reaches the lower end opening of the circulation pipe 23 and the circulation pipe 23 is shut off, the negative pressure generated around the tip of the refueling nozzle sharply increases. . The refueling nozzle is a fuel injection pipe 13 around the refueling nozzle.
When such a large negative pressure is generated, the refueling operation is automatically stopped. When the fuel level rises and the circulation pipe 23 is shut off by the fuel, the refueling is stopped. Therefore, the amount of fuel injected into the fuel chamber 7 is determined by the height of the lower end opening of the circulation pipe 23. In the present embodiment, as shown in FIG.
Since the lower end opening is disposed adjacent to the fixing portion 8, refueling is performed until the fuel level is substantially equal to the height of the fixing portion 8. In this embodiment, refueling is performed until the center surface of the separation membrane 5 becomes substantially flat. By doing so, almost all of the internal space 4 of the fuel tank 1 can be used as the fuel chamber 7, and a large amount of fuel can be stored in the fuel tank 1. When refueling is completed and the refueling nozzle is withdrawn, the fuel vapor shutoff valve 17 is closed again, and then the fuel cap 1
4 is attached.

When the operation of the engine is started and the amount of fuel in the fuel chamber 7 decreases, the fuel level in the fuel chamber 7 gradually decreases. As a result, the separation membrane 5 descends together with the fuel level, and the center plane of the separation membrane 5 projects into the fuel chamber 7. In this case, since the separation membrane 5 descends while being kept in close contact with the fuel liquid level, the amount of fuel vapor generated in the fuel tank 1 is reduced even at times other than refueling. If the amount of fuel vapor generated in the fuel tank 1 can be extremely reduced as described above, it is not necessary to reduce the size of the charcoal canister or to provide the canister itself. As the separation membrane 5 descends, the volume of the air chamber 6 gradually increases, and as a result, the pressure in the air chamber 6 gradually decreases. However, when the pressure in the air chamber 6 becomes equal to or lower than the atmospheric pressure, the atmospheric pressure relief valve 12 opens immediately, so that the pressure in the air chamber 6 does not become negative. Therefore, the pressure in the fuel chamber 7 is also maintained at or above the atmospheric pressure.

By the way, when the separation membrane 5 moves in the horizontal direction as the fuel in the fuel chamber 7 oscillates due to acceleration or deceleration or turning of the vehicle, a large load acting on the separation membrane 5, ie, tensile stress or compression. It is not preferable because stress acts. Therefore, in the present embodiment, the horizontal movement of the separation membrane 5 is restricted by inclining the side wall 3b of the lower portion 3 inward as it goes downward irrespective of the position of the separation membrane 5 according to the position of the fuel liquid level. I am trying to do it. Also, the side wall 3
Since b has the protruding portion 29, when the separation film 5 swings, the separation film 5 quickly contacts the protruding portion 29 as much as the protruding portion 29 protrudes inward. As a result, the horizontal and vertical movements of the separation membrane 5 can be further restricted. Further, since the protruding portions 29 are formed continuously from the fixing portion 8 toward the bottom wall 3c, a pair of adjacent protruding portions 2 are formed.
A recess is formed between the holes 9. These recesses hold the folds 5b protruding downward therein, whereby the movement of the separation membrane 5 can be further restricted.
As a result, it is possible to prevent an undesired large load from acting on the separation membrane 5, so that it is possible to prevent the separation membrane 5 from being damaged, and therefore, it is possible to prevent the separation membrane 5 from being more damaged. it can. Furthermore, such a protrusion 2
When the fuel cell 9 is provided, the volume of the air layer formed in the fuel chamber 7, that is, the volume of the air layer between the fuel level and the separation membrane 5 can be extremely reduced. As a result, the amount of evaporated fuel generated in the fuel chamber 7 can be extremely reduced.

In this embodiment, the valleys 30 of the folds 5 b on the upper surface of the separation membrane 5, particularly the portions 30, that is, the valleys 30 of the folds 5 b when viewed from the air chamber 6 side are provided. A ring-shaped annular rod member 32 extending along is attached. The annular bar member 32 functions as a reinforcing member for reinforcing the valley 30 of the separation membrane 5. Since the annular bar member is attached to the valley as a reinforcing member in this way, the valley stiffness is increased, so that even if fuel swinging in the fuel chamber collides with a fold, the valley is depressed from the fuel chamber side. Is prevented.

Adjacent annular rod member 32 includes a bridging member 34 comprising a thin, substantially flat sheet made of an elastic material.
Are connected to each other. The bridging member 34 is curved as shown in FIGS. 1 and 3 and extends from one valley 30 to the other valley 30 beyond the ridge of the fold 5b.
Further, as shown in FIG. 4, the cross-linking member 34
Are arranged over the entire separation membrane 5 so as to be substantially symmetrical with respect to the substantially center C of the central portion of the separation membrane. By disposing the bridging member 34 in this manner, the adjacent annular rod members 32 connected to each other by the bridging member 34 are urged to be separated from each other by the elastic action of the bridging member 34, and Since the operation is performed substantially symmetrically with respect to the substantially center C of the central portion of the separation membrane 5, the distance between the adjacent annular rod members 32 is maintained substantially equal regardless of the position in the circumferential direction. still,
It is preferable that a large number of cross-linking members are arranged particularly at corners of the separation membrane where the separation membrane is liable to cause abnormal deformation.

Therefore, according to this embodiment, the rigidity of the valleys is increased by the annular bar member, and the relative movement of the annular bar members in the direction approaching each other is limited to a certain range by the bridging member. This prevents abnormal deformation of the separation membrane, in which the folds are too close to each other in some areas, so that the folds cross over adjacent folds in other areas, and consequently these folds intersect with each other. Is done. In addition, since the cross-linking member spreads the separation membrane by separating the folds from each other, that is, urges the air chamber to have a large volume, the separation membrane adheres more closely to the liquid surface, and further suppresses the generation of fuel vapor. Can be. Since there is no urging action in the vertical direction of the annular rod member by the bridging member, that is, in the direction of increasing or decreasing the fuel, the annular rod member is movable in the vertical direction. Therefore, the vertical movement of the separation membrane accompanying the increase and decrease of the fuel is not limited by the bridging member.

In this embodiment, a ring-shaped annular bar member is used. However, this is not a limitation of the present invention. A linear bar member is partially attached to the corrugated valley, and these annular bar members are attached. The same effect can be obtained by employing a configuration in which the components are connected to each other by a bridging member. Further, the annular rod member and the bridging member can be provided not on the upper surface side but on the lower surface side of the separation membrane. However, in this case, it is necessary to employ an annular rod member and a bridging member made of a material whose physical properties do not change due to the influence of fuel. Further, it is also possible to provide an annular bar member at a peak portion as a bent portion of the waveform.

FIG. 5 shows a second embodiment of the present invention.
In this embodiment, an elastic urethane foam 36 is attached to the corrugated valley 30 of the fold 5 b on the upper surface of the separation membrane 5. The urethane foam 36 reinforces the valleys 30 of the separation membrane 5 and can maintain the distance between the folds 5b in the circumferential direction substantially equal by the elastic action, and thus has the same effect as the first embodiment. However, since there is no need to provide a bridging member as in the first embodiment, there is an advantage that the manufacturing is easy and the structure is simple. In the present embodiment, the urethane foam 36 is entirely filled along the valleys 30. However, it is also possible to partially fill the separation membrane without increasing the weight. In this case, it is necessary to arrange the urethane foam so as to be symmetric with respect to substantially the center of the center of the separation membrane so that the distance between the folds can be maintained substantially equal in the circumferential direction.

In the embodiment described so far, the fixing portion 8 is provided relatively above the fuel tank 1 so that the center surface of the separation membrane 5 is formed in the fuel chamber 7 as the amount of fuel in the fuel chamber 7 decreases. So that it projects toward However, the fixing portion 8 may be provided relatively below the fuel tank 1 so that the center surface of the separation membrane 5 projects into the air chamber 6 as the amount of fuel in the fuel chamber 7 increases. . By doing so, the separation membrane 5 is in close contact with the fuel liquid surface over almost the entire surface, so that the volume of the air layer formed in the fuel chamber 7 can be made extremely small, and thus the amount of fuel vapor generated in the fuel chamber 7 can be reduced. Can be extremely reduced. Further, the separation membrane 5 is formed in a bag shape made of a material that can be expanded and contracted to define an air chamber 6 in the internal space of the bag, and the fuel chamber 7 is formed in the internal space 4 of the fuel tank 1 located outside the bag. It can also be defined.

[0025]

According to the first aspect of the present invention, since the rigidity of the bent portion is increased, abnormal deformation of the bent portion of the separation film due to the effect of the oscillating fuel is prevented, and the separation film from the bent portion is prevented. Damage can be suppressed. According to the second aspect of the present invention, the rigidity of the entire separation membrane is increased by the cross-linking member, and the relative movement between the reinforcing members is restricted, so that abnormal deformation in which the bent portions intersect with each other is also prevented. In addition, damage to the separation membrane from the bent portion can be suppressed.

According to the third aspect of the present invention, since the relative movement of the reinforcing members is restricted within a certain range, the relative movement between the reinforcing members outside the permissible range in which the bent portions intersect with each other or abnormal deformation occurs. The movement is suppressed to prevent breakage of the separation membrane, and normal relative movement between the reinforcing members within an allowable range is enabled. According to a fourth aspect of the present invention,
Because the reinforcing member can move up and down as the fuel level moves up and down,
Abnormal deformation at the bent portion can be suppressed while ensuring vertical movement of the separation membrane at the portion where the reinforcing member is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the first embodiment of the present invention viewed from a position different from FIG.

FIG. 3 is a perspective view showing a part of an annular rod member and a bridging member according to the present invention.

FIG. 4 is a plan view showing an annular rod member and a bridging member according to the present invention.

FIG. 5 is a sectional view of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel tank 2 ... Upper part 3 ... Lower part 4 ... Internal space 5 ... Separation membrane 6 ... Air chamber 7 ... Fuel chamber 13 ... Fuel injection pipe 30 ... Valley part 32 ... Annular rod member 34 ... Cross-linking member 36 ... Urethane Foam

Claims (4)

[Claims] 1. A fuel tank comprising a separation membrane for separating an internal space of a fuel tank into a fuel chamber and an air chamber, wherein the separation membrane moves up and down with the fuel liquid surface while being in close contact with the fuel liquid surface. 3. The fuel tank according to claim 1, wherein the separation membrane is formed in a corrugated cross-sectional shape, and a reinforcing member extending along a bent portion of the corrugation is attached. 2. The fuel tank according to claim 1, wherein adjacent reinforcing members are connected to each other by a bridging member. 3. The fuel tank according to claim 2, wherein the bridging member is formed of an elastic material, and the reinforcing members are relatively movable. 4. The fuel tank according to claim 3, wherein the reinforcing member is movable in a fuel increasing / decreasing direction.