Abstract:
A fuel tank structure including: a fuel tank that is mounted to an automobile and that stores fuel; a bat shaped member that is fixed to a ceiling portion inside the fuel tank, and that maintains a contact state with the fuel by expanding or contracting according to a fluid surface height of file stored inside the fuel tank; a pump housing recessed portion that is formed to a bottom portion of the fuel tank with a fuel pump disposed therein; and a fuel flow path that is in communication with the pump housing messed portion and that extends from the pump housing recessed portion in a groove shape.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2015-123765 filed on Jun. 19, 2015, the disclosure of which is incorporated by reference herein. 
       BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present invention relates to a fuel tank structure. 
         [0004]    Related Art 
         [0005]    Japanese Patent Application Laid-Open (JP-A) No. H08-170568 describes, as a fuel tank structure mounted in a vehicle, a fuel tank structure provided with a bag shaped extending/contracting film (a bag shaped member) that is capable of expanding and contracting inside a fuel tank. A fuel pump is disposed inside a filler pipe, thereby preventing interference between the fuel pump and the extending/contracting film. 
         [0006]    However, in the fuel tank structure described in JPA No. H08-170568, since the fuel pump is disposed inside the filler pipe, there is a possibility that the fuel pump hinders fuel from flowing through the filler pipe during refueling or the like, and that the fuel injection efficiency is reduced. Moreover, in cases in which there is a small amount of fuel inside the fuel tank and the bag shaped member is in contact with a bottom portion of the fuel tank, some of the fuel is sometimes partitioned off by the bag shaped member. There is accordingly room fur improvement from the perspective of securing supply performance in which fuel is smoothly supplied to the fuel pump. 
       SUMMARY 
       [0007]    In consideration of the above circumstances, an object of the present invention is to obtain a fuel tank structure capable of securing fuel injection performance and supply performance, while suppressing the occurrence of vaporized fuel. 
         [0008]    A fuel tank structure of a first aspect of the present invention includes: a fuel tank that is mounted to an automobile and that stores fuel; a bag shaped member that is fixed to a ceiling portion inside the fuel tank, and that maintains a contact state with the fuel by expanding or contracting according to a fluid surface height of fuel stored inside the fuel tank; a pump housing recessed portion that is formed to a bottom portion of the fuel tank with a fuel pump disposed therein; and a fuel flow path that is in communication with the pump housing recessed portion and that extends from the pump housing recessed portion in a groove shape. 
         [0009]    In the fuel tank structure of the first aspect of the present invention, the bag shaped member is fixed to the ceiling portion inside the fuel tank. The bag shaped member maintains the contact state with the fuel by expanding or contracting according to the fluid surface height of the fuel. This enables the fluid surface of the fuel to be covered by bag shaped member, regardless of the fluid surface height of the fuel. Namely, the occurrence of vaporized fuel can be suppressed. 
         [0010]    The pump housing recessed portion is formed to the bottom portion of the fuel tank, and the fuel pump is disposed in the pump housing recessed portion. Thus, the fuel pump does not need to be disposed inside a filler pipe, thereby enabling fuel to be smoothly injected into the fuel tank through the filler pipe. Namely, a reduction in fuel injection efficiency can be suppressed. 
         [0011]    Since the fuel flow path extends from the pump housing recessed portion in a groove shape, fuel flows through the fuel flow path into the pump housing recessed portion and is supplied, to the fuel pump even in a state in which the bag shaped member has expanded and is in contact with the bottom portion of the fuel tank, thereby enabling fuel supply performance to be secured. 
         [0012]    A fuel tank structure of a second aspect of the present invention is the first aspect. wherein the pump housing recessed portion is formed at a center portion of the fuel tank in plan view, and the fuel flow path is formed in a radiating shape running from the pump housing recessed portion toward a side wall of the fuel tank. 
         [0013]    In the fuel tank structure of the second aspect of the present invention, the fuel flow path is formed in a radiating shape toward the side wall of the fuel tank. This enables fuel to flow smoothly to the pump housing recessed portion through the fuel flow path, even in cases in which there is a small amount of fuel inside the fuel tank. 
         [0014]    A fuel tank structure of a third aspect of the present invention is the first aspect or the second aspect, wherein the fuel flow path is sloped in a direction away from the ceiling portion on progression from a side wall of the fuel tank toward the pump housing recessed portion. 
         [0015]    The fuel tank structure of the third aspect of the present invention enables fuel inside the fuel flow path to be more effectively collected in the pump housing recessed portion than in a configuration in which the fuel flow path is not sloped. 
         [0016]    A fuel tank structure of a fourth aspect of the present invention is any one the first aspect to the third aspect, wherein the pump housing recessed portion is formed deeper than the height of the fuel pump. 
         [0017]    In the fuel tank structure of the fourth aspect of the present invention, the bag shaped member does not hit the fuel pump, even in a state in which the bag shaped member has expanded and is in contact with the bottom portion of the fuel tank, thereby enabling damage to the bag shaped member to be suppressed. 
         [0018]    As explained above, the fuel tank structure of the first aspect of the present invention has excellent advantageous effects of enabling fuel injection performance and supply performance to be secured, while suppressing the occurrence of vaporized fuel. 
         [0019]    The fuel tank structure of the second aspect and the third aspect of the present invention have an excellent advantageous effect of enabling fuel supply performance to be improved in cases in which there is a small amount of fuel inside the fuel tank. 
         [0020]    The fuel tank structure of the fourth aspect of the present invention has an excellent advantageous effect of enabling the durability performance of the bag shaped member to be secured. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0022]      FIG. 1  is a drawing schematically illustrating a fuel tank structure according to an exemplary embodiment, and illustrates a state in which fuel is stored in approximately half of a fuel tank; 
           [0023]      FIG. 2  is a drawing corresponding to  FIG. 1 , illustrating a state in which a bag shaped member is in contact with a bottom portion of the fuel tank; 
           [0024]      FIG. 3  is a cross-section illustrating a state sectioned along line  3 - 3  in  FIG. 1 ; 
           [0025]      FIG. 4  is a cross-section illustrating a state sectioned along line  4 - 4  in  FIG. 3 ; and 
           [0026]      FIG. 5  is a drawing of the fuel tank in  FIG. 1 , viewed from a different angle. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Explanation follows regarding, a fuel tank structure according to an exemplary embodiment. Note that in each of the drawings, the arrow UP indicates the upper side of a fuel tank, as appropriate. In the present exemplary embodiment, the upper side of the fuel tank is aligned with the upper side in the vehicle up-down direction. 
         [0028]    As illustrated in  FIG. 1 , a fuel tank  10  configuring the fuel tank structure according to the present exemplary embodiment is formed in a hollow shape, and is formed in a shape (such as a substantially rectangular box shape) capable of storing a liquid fuel (hereafter referred to as “fuel GS”) inside. Specifically, the fuel tank  10  is configured including two divided (upper and lower in  FIG. 1 ) tank configuration bodies  11 ,  13 , The tank configuration body  11  protrudes upward, and the tank configuration body  13  protrudes downward. Flanges  11 A,  13 A are formed to respective outer peripheral edge portions of the two tank configuration bodies  11 ,  13 , and the fuel tank  10  is configured in an overall box shape by joining the flange  11 A and the flange  13 A together. A lower face of the fuel tank  10  is supported by tank bands, not illustrated in the drawings. The tank bands are fixed to a floor panel, not illustrated in the drawings, by brackets or the like, such that the fuel tank  10  is attached to the floor panel. 
         [0029]    A substantially tube shaped filler pipe  12  is connected to the fuel tank  10 . A fuel supply port  12 A is formed in an upper end portion of the filler pipe  12 , and fuel is supplied by inserting a fuel supply gun into the fuel supply port  12 A and injecting fuel GS into the fuel tank  10 . Note that in cases in which there is a large amount of fuel GS inside the fuel tank  10 , some of the fuel GS is stored in the filler pipe  12 . 
         [0030]    The fuel supply port  12 A at an upper end of the filler pipe  12  is opened and closed by a fuel cap  14 . A fuel lid, not illustrated in the drawings, provided to a vehicle body side panel or the like, is disposed at the outside of the fuel cap  14 . 
         [0031]    In a closed state, the fuel cap  14  closes off the fuel supply port  12 A, and restricts access of a fuel supply gun into the tiller pipe  12 . In contrast thereto, when the fuel cap  14  is opened, the fuel supply port  12 A of the filler pipe  12  is open, and it becomes possible for a fuel supply gun to access the fuel supply path. 
         [0032]    A bag shaped member  16  is provided at the vehicle upper side inside the fuel tank  10 . The bag shaped member  16  is formed of a resin material that is capable of expanding and contracting, and is fixed to a ceiling portion  10 A of the fuel tank  10 . Note that “capable of expanding and contracting” referred to herein is not limited to a configuration in which the bag shaped member  16  itself expands and contracts, and includes bag shaped members with a variable volume that are contracted by being folded, or expanded by being deployed. 
         [0033]    An inlet pipe  24 , for introducing air into the bag shaped member  16 , is connected to the ceiling portion IDA of the fuel tank  10 . One end portion of the inlet pipe  24  enters inside the fuel tank  10 , and is in communication with the space inside the bag shaped member  16 . 
         [0034]    Another end side of the inlet pipe  24  is bent, and brandies into an atmosphere opening pipe  25  and an air supply pipe  27 . A pressure adjustment valve  26  is connected to the atmosphere opening pipe  25 . An opening  25 A that is open to the atmosphere is formed in an end portion of the atmosphere opening pipe  25 . 
         [0035]    A compressor  28  is connected to the air supply pipe  27 . An opening  27 A that is open to the atmosphere is formed in an end portion of the air supply pipe  27 . The pressure adjustment, valve  26  and the compressor  28  are electrically connected to an Electronic Control Unit (ECU)  30 , this being a controller. 
         [0036]    Note that the ECU  30  causes the bag shaped member  16  to expand or contract according to the fluid surface height of the fuel GS stored in the fuel tank  10  by controlling the pressure adjustment valve  26  and the compressor  28 . Namely, a contact state between the bag shaped member  16  and the fuel GS is maintained by the ECU  30  controlling the pressure adjustment valve  26  and the compressor  28 . Specifically, as illustrated in  FIG. 2 , in cases in which the amount of fuel GS has decreased and the fluid surface height has fallen, the pressure adjustment valve  26  is closed, by a signal from the ECU  30 . The compressor  28  is then operated, and compressed air is introduced into the bag shaped member  16  through the air supply pipe  27  and the inlet pipe  24 . The bag shaped member  16  thereby expands, and the contact state between the bag shaped member  16  and the fluid surface of the fuel GS is maintained. 
         [0037]    In cases in which the fluid surface has risen due to the amount of fuel GS increasing such as by refueling, the pressure adjustment valve  26  is opened by a signal from the ECU  30 . In cases in which the compressor  28  is operating, the compressor  28  is stopped by a signal from the ECU  30 . The pressure in the space inside the bag shaped member  16  thereby lowers to the atmospheric pressure. Air inside the bag shaped member  16  is accordingly pressed out through the inlet pipe  24  and discharged through the opening  25 A as the fluid surface of the fuel GS rises. The contact state between the bag shaped member  16  and the fluid surface of the fuel GS is accordingly maintained. 
         [0038]    Note that a pump housing recessed portion  10 C is formed in a bottom portion  10 B of the fuel tank  10 . As illustrated in  FIG. 3 , the pump housing recessed portion  10 C is formed at a center portion of the fuel tank  10  in plan view. A filter  18  and a fuel pump  20  are disposed inside the pump housing recessed portion  10 C. 
         [0039]    The filter  18  is formed in a substantially rectangular shape in plan view, and a supply pipe  20 B of the fuel pump  20  is attached to the filter  18 . 
         [0040]    The fuel pump  20  is disposed on the filter  18 , and is configured including a pump main body  20 A and the supply pipe  20 B. As illustrated in  FIG. 5 , the supply pipe  20 B links the pump main body  20 A and the filter  18  together, and fuel GS from which foreign matter has been removed is supplied to the pump main body  20 A through the filter  18 . A fluid feed pipe  22  is connected to the pump main body  20 A, and fuel GS that has been supplied to the pump main body  20 A is fed to an engine, not illustrated in the drawings, through the fluid feed pipe  22 . 
         [0041]    The fluid feed pipe  22  is connected at the opposite side of the pump main body  20 A to the supply pipe  20 B. The fluid feed pipe  22  is installed further downward than the bottom portion  10 B, and extends from the pump main body  20 A toward a side wall  10 D of the fuel tank  10 . The fluid feed pipe  22  is then bent upward along the side wall  10 D. Note that the tank configuration body  13  configuring the side wall  10 D in the vicinity of the fluid feed pipe  22  bulges further to the outside than the tank configuration body  11 , and a gap is provided between the tank configuration body  11  and the tank configuration body  13 . The fluid feed pipe  22  extends through this gap to the outside of the fuel tank  10 , and is connected to the engine, not illustrated in the drawings. Note that the gap between the tank configuration body  11  and the tank configuration body  13  is sealed by a sealing material, not illustrated in the drawings, and configured such that fuel GS and vaporized fuel inside the fuel tank  10  does not leak out. 
         [0042]    As illustrated in  FIG. 3 , plural fuel flow paths  10 E 1  to  10 E 8  are formed in the bottom portion  10 B of the fuel tank  10 . The fuel flow paths  10 E 1  to  10 E 8  are each formed in a groove shape with one end side in communication with the pump housing recessed portion  10 C. Another end side of the fuel flow paths  10 E 1  to  10 E 8  is positioned in the vicinity of the side wall  10 D of the fuel tank  10 . Note that when there is no distinction between each of the fuel flow paths in the below explanation, they are referred to as fuel flow paths  10 E. 
         [0043]    Note that in the present exemplary embodiment, eight fuel flow paths  10 E are formed in a radiating shape about the pump housing recessed portion  10 C. The first fuel flow path  10 E 1  extends from the pump housing recessed portion  10 C to the vicinity of the side wall  10 D at the opposite side to the fluid feed pipe  22 . The second fuel flow path  10 E 2  is formed in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the first fuel flow path  10 E 1  in plan view. 
         [0044]    The third fuel flow path  10 E 3  is formed in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the second fuel flow path  10 E 2  in plan view. The fourth fuel flow path  10 E 4  is thrilled in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the third fuel flow path  10 E 3  in plan view. 
         [0045]    The fifth fuel flow path  10 E 5  is formed in a position rotated  45  counterclockwise about the pump housing recessed portion  10 C with respect to the fourth fuel flow path  10 E 4  in plan view, and is formed in substantially a straight line with the first fuel flow path  10 E 1 . The sixth fuel flow path  10 E 6  is formed in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the fifth fuel flow path  10 E 5  in plan view, and is formed in substantially a straight line with the second fuel flow path  10 E 2 . 
         [0046]    The seventh fuel flow path  10 E 7  is formed in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the sixth fuel flow path  10 E 6  in plan view, and is formed in substantially a straight line with the third fuel flow path  10 E 3 . The eighth fuel flow path  10 E 8  is formed in a position rotated 45° counterclockwise about the pump housing recessed portion  10 C with respect to the seventh fuel flow path  10 E 7  in plan view, and is formed in substantially a straight line with the fourth fuel flow path  10 E 4 . 
         [0047]    The eight fuel flow paths  10 E are formed as described above, and the bottom portion  10 B of the fuel tank  10  is partitioned into eight by the fuel flow paths  10 E. The eight fuel flow paths IDE are each formed with substantially the same groove width, and, as illustrated in  FIG. 4 , are formed with a groove width such that the bag shaped member  16  does not enter the fuel flow paths  10 E when the bag shaped member  16  has expanded. In other words, the bag shaped member  16  is limited from expanding by the bottom portion  10 B positioned between adjacent fuel flow paths  10 E. 
         [0048]    As illustrated in  FIG. 1 ,  FIG. 2 , and  FIG. 5 , the fuel flow paths  10 E are each sloped downward (in a direction away from the ceiling portion  10 A) on progression from the side wall  10 D toward the pump housing recessed portion  10 C of the Mel tank  10 . The groove depth of the fuel flow paths  10 E with respect to the bottom portion  10 B of the fuel tank  10  is thereby shallower in the vicinity of the side wall  10 D and deeper at the pump housing recessed portion  10 C. 
         [0049]    The depth of the prunp housing recessed portion  10 C is formed deeper than the height of the fuel pump  20 . In the present exemplary embodiment, the depth of the pump housing recessed portion  10 C is formed deeper than the height of the fuel pump  20  including the thickness of the filter  18 . An upper end portion of the pump main body  20 A is thereby positioned further downward than the bottom portion  10 B of the fuel tank  10 . 
       Operation and Advantageous Effects 
       [0050]    Explanation follows regarding operation and advantageous effects of the fuel tank structure according to the present exemplary embodiment. 
         [0051]    In the present exemplary embodiment, the bag shaped member  16  is caused to expand or contract according to the fluid surface height of the fuel GS stored in the fuel tank  10 , thereby maintaining the contact state between the bag shaped member  16  and the fluid surface of the fuel GS. This enables the fluid surface of the fuel GS to be covered by the bag shaped member  16 , regardless of the fluid surface height of the fuel GS. This enables the occurrence of vaporized fuel to be suppressed. 
         [0052]    In the present exemplary embodiment, the pump housing recessed portion  10 C is formed in the bottom portion  10 B of the fuel tank  10 , and the fuel pump  20  is disposed in the pump housing recessed portion  10 C. This enables interference between the fuel pump  20  and the bag shaped member  16  to be suppressed, even in cases in which the fuel pump  20  is disposed inside the fuel tank  10 . Since the fuel pump  20  is not disposed inside the tiller pipe  12 , the fuel pump  20  does not hinder the fuel GS from flowing through the filler pipe  12 , such as during refueling. Namely, the fuel GS can be smoothly injected through the filler pipe  12  into the fuel tank  10 , enabling the fuel GS injection performance to be secured. 
         [0053]    In configurations in which the fuel pump  20  is disposed inside the filler pipe  12 , the fuel pump  20  is positioned further upward than a suction port of the supply pipe  20 B, such that negative pressure when fuel GS is being sucked up is increased and the fuel GS decreases in pressure, sometimes causing gas bubbles to occur. In contrast thereto, in the present exemplary embodiment, the fuel pump  20  is disposed in the pump housing recessed portion this being the lowest portion inside the fuel tank  10 , such that negative pressure when the fuel GS is being sucked in is minimal, and enabling the occurrence of gas bubbles in the fuel GS to be suppressed. 
         [0054]    In the present exemplary embodiment, the upper end portion of the pump main body  20 A is positioned further downward than the bottom portion  10 B of the fuel tank  10 . Thus, as illustrated in  FIG. 2 , even in a state in which the bag shaped member  16  has expanded and is in contact with the bottom portion  10 B of the fuel tank  10 , the bag shaped member  16  does not hit the fuel pump  20 . This enables damage to the bag shaped member  16  due to contact between the bag shaped member  16  and the fuel pump  20  to be avoided, and enables the durability performance of the bag shaped member  16  to be secured. 
         [0055]    In the present exemplary embodiment, the fuel flow paths  10 E each extend in a groove shape from the pump housing recessed portion  10 C, thereby enabling fuel GS to be supplied from the fuel flow paths  10 E to the fuel pump  20 , even in a state in which the bag shaped member  16  has expanded and is in contact with the bottom portion  10 B of the fuel tank  10 . Namely, the fuel GS supply performance can be secured. In this manner, the fuel GS injection performance and supply performance can be secured, while suppressing the occurrence of vaporized fuel. 
         [0056]    In particular, in the present exemplary embodiment, as illustrated in  FIG. 3 , the fuel flow paths  10 E are formed in a radiating shape about the pump housing recessed portion  10 C, and the fuel flow paths  10 E extend to the vicinity of the side wall  10 D of the fuel tank  10 . This enables fuel GS to smoothly flow through the fuel flow paths  10 E toward the pump housing recessed portion  10 C, even in cases in which there is a small amount of fuel GS inside the fuel tank  10 . As illustrated by the double-dotted dashed line L in  FIG. 2 , even in cases in which the vehicle body tilts and so on, and the fluid surface of the fuel GS is sloped with respect to the fuel tank  10 , the fuel GS can smoothly flow through the fuel flow paths  10 E to the pump housing recessed portion  10 C without being impeded by the bag shaped member  16 . This enables the fuel GS supply performance to be improved in cases in which there is a small amount of fuel GS inside the fuel tank  10 . 
         [0057]    In the present exemplary embodiment, the fuel flow paths  10 E are sloped, thereby enabling the fuel GS inside the fuel flow paths  10 E to be effectively collected in the pump housing recessed portion  10 C, compared to configurations in which the fuel flow paths  10 E are not sloped. 
         [0058]    In the present exemplary embodiment, as illustrated in  FIG. 5 , the fluid feed pipe that links the fuel pump  20  and the engine together is installed further downward than the bottom portion  10 B of the fuel tank  10 . This enables interference between the bag shaped member  16  and the fluid feed pipe  22  to be suppressed. Moreover, there is no need to separately secure a space in order to install the fluid feed pipe  22 , enabling a saving in space to be achieved. 
         [0059]    An exemplary embodiment of the present invention has been explained above; however, the present invention is not limited to the above configuration, and obviously various embodiments other than the above configuration may be implemented within a range not departing from the spirit thereof. For example, in the present exemplary embodiment, the upper end portion of the pump main body  20 A is positioned further downward than the bottom portion  10 B of the fuel tank  10 ; however, the present invention is not limited thereto. Namely, even in cases in which the upper end portion of the pump main body  20 A is positioned further upward than the bottom portion  10 B, as long as the configuration is not one in which the bag shaped member  16  is worn by interference between the bag shaped member  16  and the pump main body  20 A, similar advantageous effects to those in the present exemplary embodiment can be obtained. 
         [0060]    In the present exemplary embodiment, eight fuel flow paths  10 E are formed; however, configuration is not limited thereto, and the number of fuel flow paths  10 E is not specified. There is also no limitation to a configuration in Which the fuel flow paths  10 E are formed in a radiating shape, and, for example, a configuration may be applied in which plural fuel flow paths  10 E are formed from the pump housing recessed portion  10 C at uneven spacings. 
         [0061]    It is preferable that the pump housing recessed portion  10 C is formed to the center portion of the fuel tank  10  in plan view, from the perspective of effectively supplying fuel GS to the fuel pump  20 ; however, there is no particular limitation to the position where the pump housing recessed portion  10 C is formed. For example, the pump housing recessed portion  10 C may be formed in the vicinity of the side wall to of the fuel tank  10 . 
         [0062]    In the present exemplary embodiment the fuel flow paths  10 E are caused to slope; however, configuration is not limited thereto. For example, a configuration may be applied formed with fuel flow paths that are substantially parallel to the bottom portion  10 B of the fuel tank  10 .