Patent Publication Number: US-2022212739-A1

Title: Fuel tank

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The disclosure of Japanese Patent Application No. 2021-000164 filed on Jan. 4, 2021, including specification, drawings and claims is incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present invention relates to a fuel tank. 
     As a tank cap of a fuel tank, a tank cap has been known that implements unlocking and locking by using a mechanical key (see, for example, Patent Literature 1). The tank cap disclosed in Patent Literature 1 is provided with a lock mechanism that implements locking by inserting a lock bar into a lock cover. When the mechanical key is inserted into a key hole of the lock mechanism and is rotated, the lock bar is removed from the lock cover, thereby implementing unlocking. In recent years, there has been a demand for high functionality for a tank cap of a fuel tank, and there has been a demand for unlocking and locking of the tank cap by a smart key using wireless communication. 
     Patent Literature 1: JP-A-H9-024874 
     SUMMARY 
     According to one advantageous aspect of the present invention, there is provided a fuel tank according to an aspect of the present invention including a tank panel in which a storage space of a fuel is formed, a tank inlet that is fixed to the tank panel, and a tank cap that allows the tank inlet to be opened and closed. The tank inlet includes an inlet plate which has a bottomed cylindrical shape and to which the tank cap is attached, an inlet pipe that protrudes from a bottom wall of the inlet plate into the storage space, and a separator configured to separate the fuel entering from the storage space into a liquid component and a gas component. The separator is supported by the bottom wall of the inlet plate in the storage space, and the separator is disposed on an outer side of the inlet pipe and on an inner side relative to an outer edge of the inlet plate in a bottom view of the tank inlet. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a left side view of a straddle-type vehicle according to an embodiment. 
         FIG. 2  is a perspective view of a fuel tank of the present embodiment. 
         FIG. 3A  is a perspective view of a tank inlet according to the present embodiment. 
         FIG. 3B  is another perspective view of the tank inlet according to the present embodiment. 
         FIG. 4A  is a perspective view of a tank cap of the present embodiment. 
         FIG. 4B  is another perspective view of the tank cap of the present embodiment. 
         FIG. 5  is a plan view of a cap body and the tank inlet according to the present embodiment. 
         FIG. 6A  is a view showing an arrangement position of a separator according to the present embodiment. 
         FIG. 6B  is another view showing the arrangement position of the separator according to the present embodiment. 
         FIG. 7  is a diagram showing a difference in space capacity between fuel tanks of a comparative example and a mechanical key specification. 
         FIG. 8  is a diagram showing a difference in space capacity between fuel tanks of the present embodiment and the mechanical key specification. 
         FIG. 9  is a diagram showing an example of the fuel tank in a parked state according to the present embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLIFIED EMBODIMENTS 
     A tank cap of a mechanical key specification is provided with a separator that separates a fuel from a fuel tank into gas and liquid. Similarly, a tank cap of a smart key specification is also provided with a separator, but since an electric component is added to the tank cap, a cap size thereof is larger than that of the tank cap of the mechanical key specification. In addition, with respect to the tank cap of the smart key specification, a basic structure of a fuel tank employing the tank cap of the mechanical key specification cannot be diverted, and manufacturing cost increases. Such a problem may occur not only due to a difference in specification between the mechanical key and the smart key but also due to a change in a cap structure. 
     The present invention has been made in view of the above, and an object thereof is to provide a fuel tank capable of suppressing an increase in a cap size and diverting an existing basic structure. 
     A fuel tank according to an aspect of the present invention includes a tank panel in which a storage space of a fuel is defined. A tank inlet is fixed to the tank panel, and the tank inlet is opened and closed by a tank cap. The tank cap is attached to a bottomed cylindrical inlet plate of the tank inlet, and an inlet pipe protrudes from a bottom wall of the inlet plate into the storage space. A separator is supported by the bottom wall of the inlet plate in the storage space of the tank panel, and a fuel entering from the storage space to the tank cap side is separated into a liquid component and a gas component by the separator. Since the separator is provided outside the tank cap, a cap size of the tank cap is not increased by the separator. The separator is disposed on an outer side of the inlet pipe and on an inner side relative to an outer edge of the inlet plate in a bottom view of the inlet plate, that is, on an inner side of a projection plane of the inlet plate in a bottom view. The separator does not protrude from the inlet plate, and a change in a basic structure of the fuel tank due to presence or absence of the separator does not occur. Accordingly, manufacturing cost can be reduced by diverting existing manufacturing equipment or the like. 
     Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings.  FIG. 1  is a left side view of a straddle-type vehicle according to the present embodiment. In the following drawings, an arrow FR indicates a vehicle front side, an arrow RE indicates a vehicle rear side, an arrow L indicates a vehicle left side, and an arrow R indicates a vehicle right side. 
     As illustrated in  FIG. 1 , a straddle-type vehicle  1  includes various types of components such as an engine  16  and an electrical system that are mounted on a twin spar-type vehicle body frame  10  formed by aluminum casting. The vehicle body frame  10  includes a pair of main frames  12  branching from a head pipe  11  (see  FIG. 2 ) to the left and right and extending toward the rear side, and a pair of down frames (not shown) branching from the head pipe  11  to the left and right and extending toward a lower side. A rear portion of the engine  16  is supported by the pair of main frames  12 , and a front portion of the engine  16  is supported by the pair of down frames. By supporting the engine  16  with the vehicle body frame  10 , rigidity of the entire vehicle is secured. 
     Front-side portions of the main frames  12  serve as tank rails  13  positioned above the engine  16 , and a fuel tank  40  is supported by the tank rails  13 . Rear-side portions of the main frames  12  serve as body frames  14  positioned behind the engine  16 , and swing arms  18  are swingably supported at substantially middle positions of the body frames  14  in an up-down direction. Seat rails (not shown) and a back stay  15  extend toward the rear side from upper portions of the body frames  14 . A rider seat  21  and a pillion seat  22  are supported on the seat rails on a rear side of the fuel tank  40 . 
     A pair of front forks  23  are supported on the head pipe  11  via a steering shaft (not shown) so as to be steered. A front wheel  25  is rotatably supported by lower portions of the front forks  23 , and an upper portion of the front wheel  25  is covered with a front fender  24 . The swing arms  18  extend toward the rear side from the body frames  14 . A rear wheel  27  is rotatably supported at rear ends of the swing arms  18 , and an upper side of the rear wheel  27  is covered with a rear fender  26 . The engine  16  is coupled to the rear wheel  27  via a chain drive type transmission mechanism, and power from the engine  16  is transmitted to the rear wheel  27  via the transmission mechanism. 
     Various covers are attached to the vehicle body frame  10  of the straddle-type vehicle  1  as a vehicle body exterior. For example, a front portion of the vehicle is covered with a body cowl  31  and a center body cowl  32 . In a vehicle side portion, a front side of the fuel tank  40  is covered with a pair of side covers  33 , and a rear side of the fuel tank  40  is covered with a pair of frame covers  34 . A vehicle upper portion is covered with a tank cover  35 , the rider seat  21 , and the pillion seat  22 . A lower side of the rider seat  21  and the pillion seat  22  is covered with a pair of rear covers  36 . A side stand  19  is provided on a left side surface of the straddle-type vehicle  1  that allows a vehicle body to self-stand in an inclined manner. 
     In the fuel tank  40  of the straddle-type vehicle  1 , it is desired to adopt a tank cap of a smart key specification in addition to a tank cap of a mechanical key specification. In the tank cap of the mechanical key specification, a mechanical key is inserted into a key hole of the tank cap, and a lock bar is moved by rotation of the mechanical key, so that the tank cap is mechanically locked and unlocked. On the other hand, in the tank cap of the smart key specification, a smart key and a controller communicate with each other, and a lock bar is moved by the controller via an actuator, so that the tank cap is electrically locked and unlocked. 
     Each of the tank cap of the mechanical key specification and the tank cap of the smart key specification is provided with a separator that separates a fuel entering from an inside of the tank to the tank cap side into gas and liquid. In the tank cap of the smart key specification, it is necessary to incorporate an electric component such as a solenoid, and when a separator having the same volume as that of the tank cap of the mechanical key specification is provided in the tank cap of the smart key specification, the cap size increases. In addition, there is a problem that basic structures of the fuel tank differ due to a difference in shapes of the tank cap of the mechanical key specification and the tank cap of the smart key specification. 
     For this reason, for the same machine, it is necessary to prepare mold jigs and manufacturing equipment of the tank panel separately in order to manufacture the fuel tanks of the mechanical key specification and the smart key specification, and manufacturing cost of the fuel tank increases. Therefore, in the fuel tank  40  of the present embodiment, a separator in a tank cap  70  is minimized, and an external separator  61  is attached to a tank inlet  50  to suppress an increase in cap size (see  FIG. 3B ). In addition, by devising an arrangement position of the separator  61 , the basic structure of the fuel tank is made common to the tank caps of the mechanical key specification and the smart key specification. 
     Hereinafter, the fuel tank will be described with reference to  FIGS. 2 to 5 .  FIG. 2  is a perspective view of the fuel tank according to the present embodiment.  FIG. 3A  is a perspective view of the tank inlet of the present embodiment as viewed from above.  FIG. 3B  is a perspective view of the tank inlet of the present embodiment as viewed from below.  FIG. 4A  is a perspective view of the tank cap of the present embodiment as viewed from above.  FIG. 4B  is a perspective view of the tank cap of the present embodiment as viewed from below.  FIG. 5  is a plan view of a cap body and the tank inlet according to the present embodiment. In  FIG. 2 , the tank cover is removed from the fuel tank. In  FIG. 5 , a separator cover is removed from an in-cap separator. 
     As shown in  FIG. 2 , a front portion of the fuel tank  40  is supported near the head pipe  11  via a bracket  41 , and a rear portion of the fuel tank  40  is supported by the upper portions of the body frames  14  (see  FIG. 1 ) via a bracket  42 . The fuel tank  40  is supported above the pair of main frames  12 , and the front portion of the fuel tank  40  is formed in a substantially U-shape in a front view so as to cover the pair of main frames  12  from the left and right sides. A tank panel  43  of the fuel tank  40  is formed by joining an outer edge of an outer panel  44  whose lower surface is open and an outer edge of an inner panel  45  whose upper surface is open. A storage space S (see  FIG. 8 ) of a fuel is formed by joining the outer panel  44  and the inner panel  45 . 
     A circular opening is formed in an upper portion of the outer panel  44 , and the tank inlet  50  in which a fuel supply port is formed is fixed to the circular opening. The tank cap  70  for opening and closing the fuel supply port is attached to the tank inlet  50 . In a state where the tank cap  70  is opened, a fueling nozzle is inserted into the fuel supply port of the tank inlet  50 , so that the fuel is supplied from the fueling nozzle to the storage space S of the tank panel  43 . Although the tank inlet  50  appears to be exposed around the tank cap  70  in  FIG. 2 , the tank cap  70  is actually covered with the tank cover  35  (see  FIG. 1 ) on the outer panel  44 . 
     As shown in  FIGS. 3A and 3B , the tank inlet  50  includes a bottomed cylindrical inlet plate  51  to which the tank cap  70  (see  FIGS. 4A and 4B ) is to be attached. A peripheral wall  52  of the inlet plate  51  is formed in a circular shape, and the peripheral wall  52  is joined to an inner edge of the circular opening of the outer panel  44 . An inlet pipe  54  serving as the fuel supply port is attached to a center of a bottom wall  53  of the inlet plate  51 . An upper end of the inlet pipe  54  slightly protrudes from the bottom wall  53  of the inlet plate  51  toward the tank cap  70  side, and a lower end of the inlet pipe  54  greatly protrudes from the bottom wall  53  of the inlet plate  51  toward the storage space S. 
     A breather pipe  55  that guides a gas component in the inlet plate  51  to the outside of the fuel tank  40  is connected to the bottom wall  53  of the inlet plate  51  in the vicinity of the inlet pipe  54 . A portion of the bottom wall  53  of the inlet plate  51  in the vicinity of the peripheral wall  52  is recessed, and a drain pipe  57  for discharging liquid droplets in the inlet plate  51  is connected to a bottom surface of a recess  56 . Since an inlet of the drain pipe  57  is exposed to the bottom surface of the recess  56 , droplets on the bottom wall  53  of the inlet plate  51  are easily collected to the drain pipe  57 . Screw holes  59  of cap nuts  58  by which the tank cap  70  is fixed are exposed from the bottom wall  53  of the inlet plate  51 . 
     A lower surface of the bottom wall  53  of the inlet plate  51  is exposed to the storage space S. The separator  61  is supported on the lower surface of the bottom wall  53  that separates the fuel entering from the storage space S into a liquid component and a gas component. The separator  61  is formed by joining a bottom plate  63  to a cylindrical case  62  having an upper base. A gas-liquid separation chamber  64  (see  FIG. 8 ) for separating the fuel into gas and liquid is formed by joining the cylindrical case  62  and the bottom plate  63 . An upper wall of the cylindrical case  62  is joined to the bottom wall  53  of the inlet plate  51 , and a communication hole  65  is formed that passes through a joint portion of the upper wall of the cylindrical case  62  and the bottom wall  53  of the inlet plate  51 . 
     A pair of return holes  66  for returning a liquid fuel in the gas-liquid separation chamber  64  to the storage space S are formed in a bottom wall (bottom plate  63 ) of the separator  61 . A vent hole  67  through which the gas-liquid separation chamber  64  and the storage space S are communicated is formed in a side wall of the separator  61  (cylindrical case  62 ). The vent hole  67  is formed in the side wall of the separator  61  at a position close to the bottom wall  53  of the inlet plate  51 . Although details will be described later, the gas-liquid separation chamber  64  of the separator  61  and the storage space S of the tank panel  43  are in communication with each other, so that a decrease in space capacity for allowing for volume expansion of the fuel at the time of temperature rise in the storage space S is suppressed. 
     As shown in  FIGS. 4A and 4B , the tank cap  70  has an annular cap body  71  to which a circular cap plate  72  is attached so as to be opened and closed. An annular cap cover  74  that covers a periphery of the cap plate  72  is attached to a front surface of the cap body  71  via four bolts  73 . A rear portion of the cap cover  74  is partially cut out to expose a hinge portion  75  of the cap body  71 , and the cap plate  72  is pivotally supported by the hinge portion  75 . A front portion of the cap cover  74  covers a lock portion  76  (see  FIG. 5 ) of the cap body  71 , and the cap plate  72  is locked in a closed state by the lock portion  76 . 
     An actuator  77 , for example, is attached to the cap body  71  as an electric component that locks and unlocks the cap plate  72 . The actuator  77  is attached to the front portion of the cap body  71 , and when a wireless signal from a smart key is received, the lock portion  76  is driven by the actuator  77  to switch between locking and unlocking of the cap plate  72 . An in-cap separator  87  (see  FIG. 5 ), which will be described later, is formed in a right portion of the cap body  71 . 
     A knob  79  is formed on a front surface of the cap plate  72 , and a cap seal  81  is screwed to a back surface of the cap plate  72 . When the knob  79  on the front surface of the cap plate  72  is pulled up, the cap plate  72  is opened and closed with the hinge portion  75  serving as a fulcrum. When the cap plate  72  is closed, the upper end of the inlet pipe  54  (see  FIG. 3A ) is sealed by the cap seal  81 . A discharge hole  82  facing an inlet of the breather pipe  55  and an inflow hole  83  facing the separator  61  are formed in the back surface of the cap body  71 , and O-rings  84  and  85  are fitted around the discharge hole  82  and the inflow hole  83  respectively. 
     As shown in  FIG. 5 , the cap body  71  is positioned inside the inlet plate  51 , and three bolts  86  penetrating the cap body  71  are fixed by the cap nuts  58  (see  FIG. 3B ) of the inlet plate  51 . The in-cap separator  87  is formed in the right portion of the cap body  71  and has a gas-liquid separation chamber  89  for separating the fuel entering from the storage space S into a liquid component and a gas component. 
     The inflow hole  83  is formed in the in-cap separator  87 , and the inflow hole  83  is in communication with the communication hole  65  (see  FIG. 3A ) of the inlet plate  51  and the separator  61 . The gas-liquid separation chamber  89  of the in-cap separator  87  is in communication with the gas-liquid separation chamber  64  (see  FIG. 8 ) of the separator  61  through the inflow hole  83  and the communication hole  65 . With the in-cap separator  87  and the separator  61  of the tank inlet  50 , capacity of all the gas-liquid separation chambers of the entire tank cap  70  is sufficiently secured. The separator  61  is disposed on a back side of the in-cap separator  87  with the bottom wall  53  of the inlet plate  51  sandwiched between the separator  61  and the in-cap separator  87 , and the in-cap separator  87  and the separator  61  are compactly disposed. 
     The discharge hole  82  is formed in the vicinity of the hinge portion  75  of the in-cap separator  87 , and the discharge hole  82  is in communication with the inlet (see  FIG. 3A ) of the breather pipe  55 . A gas component of the fuel in the gas-liquid separation chamber  89  enters the breather pipe  55  from the discharge hole  82 , and the gas component is discharged to the outside of the fuel tank  40  through the breather pipe  55 . Since the breather pipe  55  is connected not to the separator  61  in the storage space S but to the in-cap separator  87  located above the tank, a degree of freedom in shape of the separator  61  is increased, and the capacity of all the gas-liquid separation chambers can be secured. 
     The tank cap  70  is positioned at a center of the fuel tank  40  (see  FIG. 2 ) in a vehicle width direction, and a plate center line L 2  perpendicular to an opening and closing axis L 1  of the cap plate  72  (see  FIG. 4A ) coincides with a vehicle body center line extending in a vehicle front-rear direction. 
     The arrangement position of the separator will be described with reference to  FIGS. 6A and 6B .  FIG. 6A  is a bottom view of the tank inlet, showing the arrangement position of the separator according to the present embodiment.  FIG. 6B  is a side view of the tank inlet, showing the arrangement position of the separator according to the present embodiment. 
     As shown in  FIGS. 6A and 6B , the separator  61  is disposed on an outer side of the inlet pipe  54  and on an inner side relative to an outer edge of the inlet plate  51  in a bottom view of the inlet plate  51 . The separator  61  is formed in an elliptical shape in the bottom view. A length of a minor axis of the separator  61  is smaller than a width from an inner edge to the outer edge of the inlet plate  51 , and a diameter of the inlet pipe  54  is substantially equal to a length of a major axis of the separator  61 . Therefore, the separator  61  falls inside a projection plane of the inlet plate  51  in the bottom view, and the separator  61  substantially overlaps a projection plane of the inlet pipe  54  in the side view. 
     Since the separator  61  does not protrude from the inlet plate  51  in the bottom view and the separator  61  hardly protrudes from the inlet pipe  54  in the side view, a significant change in a shape, a size, and the like of the tank inlet  50  due to presence or absence of the separator  61  does not occur. A basic structure of the fuel tank  40  can be made common between the tank cap  70  of the smart key specification as in the present embodiment and a tank cap of the mechanical key specification without the separator  61 . Therefore, the manufacturing cost is reduced by using the same mold jig or manufacturing equipment for forming the tank panel  43  in the smart key specification and the mechanical key specification. 
     In addition, since the separator  61  is supported by the inlet plate  51  and the separator  61  is provided outside the tank cap  70 , the cap size of the tank cap  70  does not increase. The breather pipe  55  is connected to the bottom wall  53  of the inlet plate  51  behind the separator  61 , and the drain pipe  57  is connected to the bottom wall  53  of the inlet plate  51  at a position symmetrical with (opposite to) the separator  61  with respect to the inlet pipe  54 . Since the drain pipe  57  is sufficiently separated from the separator  61 , the bottom wall  53  of the inlet plate  51  can be expanded toward the storage space S to form the recess  56  at a connection portion of the drain pipe  57 . 
     The space capacity of the fuel tank will be described with reference to  FIGS. 7 to 9 .  FIG. 7  is a diagram showing a difference in space capacity between fuel tanks of a comparative example and a mechanical key specification.  FIG. 8  is a diagram showing a difference in space capacity between fuel tanks of the present embodiment and the mechanical key specification.  FIG. 9  is a diagram showing an example of the fuel tank in a parked state according to the present embodiment. In  FIGS. 7 and 8 , the left side shows a fuel tank of the smart key specification, and the right side shows the fuel tank of the mechanical key specification. The fuel tank of the comparative example in  FIG. 7  is the same as the fuel tank of the present embodiment except for a location where the vent hole is formed. 
     As shown in  FIG. 7 , inlet plates  91  and  96  of fuel tanks  90  and  95  of the smart key specification (comparative example) and the mechanical key specification enter the storage space S from tank panels  92  and  97  respectively. The inlet plates  91  and  96  are joined to inlet pipes  93  and  98  by brazing or the like, and vent holes  94  and  99  are formed in peripheral walls of the inlet pipes  93  and  98  below joining ranges. The number of components of the tank cap of the smart key specification is greater than that of tank cap of the mechanical key specification. Therefore, a bottom surface of the inlet plate  91  of the smart key specification is lower than a bottom surface of the inlet plate  96  of the mechanical key specification, and a formation position of the vent hole  94  is lower than that of the vent hole  99 . 
     With respect to both of the storage spaces S of the fuel tanks  90  and  95  of the smart key specification and the mechanical key specification, a space capacity C for allowing for volume expansion of the fuel due to temperature rise is required. The space capacity C is a volume measuring from a liquid surface  100  to the vent holes  94  and  99  at the time when the fuel tank is full of fuel. Since the vent hole  94  of the fuel tank  90  is lower than the vent hole  99  of the fuel tank  95 , an upper limit height of the space capacity C of the fuel tank  90  is lower than that of the fuel tank  95 . Therefore, in order for the fuel tank  90  to obtain the space capacity C similar to that of the fuel tank  95 , the liquid surface  100  at the time when the fuel tank  90  is full of fuel needs to be lower than that of the fuel tank  95 , and capacity for storing fuel in the fuel tank  90  decreases. 
     As shown in  FIG. 8 , in the fuel tank  40  of the present embodiment, the vent hole  67  is formed in the separator  61 . Since the separator  61  does not need to have a strength against insertion and removal of a fueling nozzle such as the inlet pipe  54 , the separator  61  can be fixed to the inlet plate  51  without being subjected to brazing or the like. Therefore, in the separator  61 , the vent hole  67  can be formed at a position close to the bottom wall  53  of the inlet plate  51 . Therefore, by aligning heights of the vent holes  67  and  99  of the fuel tanks  40  and  95  of the smart key specification and the mechanical key specification, the space capacity C similar to that of the fuel tank  95  can be obtained without reducing the capacity for storing fuel of the fuel tank  40 . 
     As shown in  FIG. 9 , when the straddle-type vehicle  1  (see  FIG. 1 ) is parked, the fuel tank  40  is inclined to one of the right and left sides (the left side in the present embodiment), and a space on the right side of the fuel tank  40  is larger than a space on the left side. The separator  61  is disposed on a side (the right side in the present embodiment) opposite to the side stand  19  (see  FIG. 1 ) with the inlet pipe  54  located therebetween. Further, the vent hole  67  of the separator  61  opens toward an outer side in a radial direction of the inlet pipe  54 , and the vent hole  67  is far away from the side stand  19 . Since the vent hole  67  is separated upward from the liquid surface  100  of the fuel due to the inclination of the vehicle body, the space capacity C is secured, and the capacity for storing fuel can be increased. 
     As described above, according to the present embodiment, since the separator  61  is supported by the bottom wall  53  of the inlet plate  51  and the separator  61  is provided outside the tank cap  70 , the cap size of the tank cap  70  is not increased. In addition, the separator  61  is positioned on the inner side of the projection plane of the inlet plate  51  in a bottom view, and the separator  61  does not protrude from the inlet plate  51 . Accordingly, since a change in the basic structure of the fuel tank  40  due to presence or absence of the separator  61  does not occur, the manufacturing cost can be reduced by diverting existing manufacturing equipment or the like. 
     The fuel tank of the present embodiment can also be appropriately applied to other straddle-type vehicles such as a buggy-type automatic three-wheeled vehicle. Here, the straddle-type vehicle is not limited to a general vehicle on which a rider drives the vehicle in a posture of straddling a seat, and further includes a scooter-type vehicle on which a rider drives the vehicle without straddling a seat. 
     In addition, although an example in which the separator is added to the tank inlet of the fuel tank of the smart key specification has been described in the present embodiment, the separator may be added to a tank inlet of a fuel tank of a mechanical key specification. For example, even when a new component needs to be mounted on a tank cap of a mechanical key specification, an increase in the cap size due to addition of the separator to the tank inlet can be suppressed. 
     In addition, although the in-cap separator is provided in the tank cap and the separator is provided at the tank inlet in the present embodiment, the separator may be provided at least at the tank inlet. 
     In addition, although the vent hole is formed in the separator in the present embodiment, the vent hole may be formed in the inlet pipe. 
     In addition, although the separator is provided on the side opposite to the side stand with the inlet pipe located therebetween in the present embodiment, a positional relationship between the separator and the side stand is not particularly limited. 
     In addition, although the separator is formed by joining the bottom plate to the cylindrical case having an upper base in the present embodiment, the shape and structure of the separator are not particularly limited. The upper wall of the cylindrical case may be open, and the side wall of the cylindrical case may be fixed to the bottom wall of the inlet plate. The cylindrical case and the bottom plate may be integrally formed. 
     In addition, although the breather pipe and the drain pipe pass through the inside of the tank panel in the present embodiment, the breather pipe and the drain pipe may pass through the outside of the tank panel. 
     As described above, the fuel tank ( 40 ) of the present embodiment includes the tank panel ( 43 ) in which the storage space (S) of a fuel is formed, the tank inlet ( 50 ) that is fixed to the tank panel, and the tank cap ( 70 ) that allows the tank inlet to be opened and closed. The tank inlet includes the bottomed cylindrical inlet plate ( 51 ) to which the tank cap is attached, the inlet pipe ( 54 ) that protrudes from the bottom wall ( 53 ) of the inlet plate into the storage space, and the separator ( 61 ) that separates the fuel entering from the storage space into a liquid component and a gas component. The separator is supported by the bottom wall of the inlet plate in the storage space, and the separator is disposed on the outer side of the inlet pipe and on the inner side relative to the outer edge of the inlet plate in the bottom view of the tank inlet. According to this configuration, since the separator is supported by the bottom wall of the inlet plate in the storage space of the tank panel and the separator is provided outside the tank cap, the cap size of the tank cap is not increased. In addition, the separator is positioned on the inner side of the projection plane of the inlet plate in a bottom view, and the separator does not protrude from the inlet plate. Accordingly, since a change in the basic structure of the fuel tank due to presence or absence of the separator does not occur, the manufacturing cost can be reduced by diverting existing manufacturing equipment or the like. 
     In the fuel tank of the present embodiment, the separator is formed with the vent hole ( 67 ) through which the gas-liquid separation chamber ( 64 ) of the separator and the storage space are communicated with each other. According to this configuration, since the vent hole is formed in the separator on which an external force is less likely to act, the vent hole can be brought close to the bottom wall of the inlet plate. Since the upper limit height of the space capacity is increased, the capacity for storing fuel can be increased. 
     In the fuel tank of the present embodiment, the separator is disposed on the side opposite to the side stand ( 19 ), which allows the vehicle body to self-stand in an inclined manner, with the inlet pipe located therebetween. According to this configuration, since the vent hole of the separator is separated upward from the liquid surface of the fuel by the inclination of the vehicle body, the space capacity is secured, and the capacity for storing fuel can be increased. 
     In the fuel tank of the present embodiment, the vent hole opens toward an outer side in the radial direction of the inlet pipe. According to this configuration, the vent hole of the separator can be further separated upward from the liquid surface of the fuel by the inclination of the vehicle body. 
     In the fuel tank of the present embodiment, the tank cap includes the in-cap separator ( 87 ) that separates the fuel entering from the storage space into a liquid component and a gas component, and the gas-liquid separation chamber ( 89 ) of the in-cap separator is in communication with the gas-liquid separation chamber of the separator through the communication hole ( 65 ) formed in the bottom wall of the inlet plate. According to this configuration, the capacity of the gas-liquid separation chamber can be sufficiently secured with the separator and the in-cap separator, and the separator and the in-cap separator can be disposed compactly. 
     In the fuel tank of the present embodiment, the breather pipe ( 55 ) for discharging the gas component of the fuel is in communication with the in-cap separator. According to this configuration, a location where the vent hole is formed with respect to the separator in the storage space is not restricted by the breather pipe. 
     Although the present embodiment has been described, the above-described embodiment and a modification may be combined in whole or in part as another embodiment. 
     The technique of the present invention is not limited to the above-described embodiment, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea of the present invention. Further, the present invention may be implemented using other methods as long as the technical idea can be implemented by the methods through advance of the technology or other derivative technology. Accordingly, the claims cover all embodiments that may be included within the scope of the technical idea.