Patent Publication Number: US-2020282825-A1

Title: Fuel tank system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a Divisional Application of application Ser. No. 15/910,154, filed Mar. 2, 2018, which is based on Japanese patent application No. 2017-55629 filed on Mar. 22, 2017, the entire contents of each of which are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a fuel tank system. 
     BACKGROUND 
     In one type of conventional fuel tank systems, a control valve is provided to open and close a tank passage, which connects a fuel tank and a canister. For example, in a fuel tank system disclosed in JP 2001-206081A, a float valve and a pressure sensor are provided. The float valve is driven by buoyant force and closes a tank passage when fuel is filled up in a fuel tank. The pressure sensor detects an inner pressure of the fuel tank. In this fuel tank system, the inner pressure of the fuel tank increases rapidly in refilling the fuel tank, when the fuel is filled up in the fuel tank and float valve closes the tank passage. When the pressure sensor detects the rapid pressure change, the control valve is controlled to close the tank passage. 
     According to the fuel tank system described above, the float valve closes the tank passage to raise the inner pressure of the fuel tank and the pressure sensor detects the rise of the tank inner pressure to control the control valve to close. This fuel tank system needs both of the float valve and the pressure sensor, thus complicating whole system configuration. 
     In case that the float valve is eliminated in the fuel tank system disclosed above, the inner pressure of the fuel tank rises only slightly in the course of refilling of fuel into the fuel tank. As a result, the pressure sensor may not be able to detect the rise of the inner pressure of the fuel tank. When the pressure sensor fails to detect the rise of the inner pressure of the fuel tank, fuel is likely to be supplied to the fuel tank continuously even after the fuel tank is filled up. As a result, the fuel is likely to flow to the canister side through the tank passage. The fuel is likely to overflow from a filler neck of the fuel tank. 
     SUMMARY 
     It is therefore an object to provide a fuel tank system, which appropriately controls a flow amount of fluid flowing through a tank passage at time of fill-up of a fuel tank, in simple configuration. 
     According to one aspect, a fuel tank system comprises a tank passage, a canister, an electric control valve, a fill-up detection part and a control part. The tank passage has one end connected to a fuel tank, which stores fuel. The canister is connected to an other end of the tank passage for adsorbing evaporated fuel generated by evaporation of the fuel in the fuel tank. The electric control valve is operable with current supply and controls an amount of fluid flowing through the tank passage by varying an open rate of the tank passage. The fill-up detection part detects that the fuel tank is filled up with fuel based on a fuel level in the fuel tank without detecting an inner pressure of the fuel tank. The control part controls an operation of the electric control valve. The control part controls the electric control valve in a valve closing direction to decrease the open rate of the tank passage, when the fill-up detection part detects that the fuel tank is filled up with fuel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a fuel tank system according to a first embodiment; 
         FIG. 2  is a schematic view showing a fuel tank system according to a second embodiment; 
         FIG. 3  is a schematic view showing a fuel tank system according to a third embodiment; 
         FIG. 4  is a schematic view showing a fuel tank system according to a fourth embodiment; 
         FIG. 5  is a time chart showing an exemplary operation of the fuel tank system according to the fourth embodiment; 
         FIG. 6  is a time chart showing an exemplary operation of a fuel tank system according to a fifth embodiment; 
         FIG. 7  is a schematic view showing one state of an electric control valve of a fuel tank system according to a sixth embodiment; and 
         FIG. 8  is a schematic view showing the other state of the electric control valve of the fuel tank system according to the sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT 
     A fuel tank system will be described below with reference to multiple embodiments. Substantially same structural parts are designated with same reference numerals among the multiple embodiments for brevity. 
     First Embodiment 
     A fuel tank system according to a first embodiment is shown in  FIG. 1 . A fuel tank system  10  according to the first embodiment is provided in a vehicle  1  provided with an engine  2 , which is a gasoline internal combustion engine. The vehicle  1  includes, in addition to the engine  2  and the fuel tank system  10 , an intake pipe  2  and a fuel tank  11 . The engine  2  generates a driving power for driving the vehicle  1 . The engine  2  is supplied with gasoline as fuel to drive the vehicle  1 . 
     The intake pipe  3  is connected to the engine  2 . An intake passage  4  is formed inside the intake pipe  3 . One end of the intake passage  4  is connected to a combustion chamber of the engine  2  and the other end of the intake passage  4  is open to atmosphere. The intake passage  4  leads air in the atmosphere into the combustion chamber of the engine  2 . The air (also referred to as intake air) taken into the combustion chamber through the intake passage  4  is mixed with fuel, which is injected from a fuel injection valve (not shown) for example, to provide mixture of air and fuel. The engine  2  operates by combustion of the mixture in the combustion chamber. A throttle valve  5  is provided in the intake passage  4 . The throttle valve  5  regulates an amount of air taken into the engine  2  by changing an air flow area in the intake passage  4 , that is, an open rate of the intake passage  4 , by regulating an open angle of the throttle valve  5 . 
     The fuel tank  11  stores fuel, which is to be supplied to the engine  2 . A fuel pump  6  is provided inside the fuel tank  11 . The fuel pump  6  takes in the fuel in the fuel tank  11  and discharges the fuel after pressurization. The fuel discharged from the fuel pump  6  is supplied to the engine  2  through a fuel pipe, a fuel rail and the fuel injection valve, which are not shown. The fuel tank  11  is formed of a tank body  110 , a filler neck (fuel supply inlet)  12  and the like. The tank body  110  is made of a metal or resin and formed in a box shape, for example. The tank body  110  has a tank inner space  111  in its inside to store fuel therein. 
     The filler neck  12  is connected to the tank body  110 . One end of the filler neck  12  is connected to the tank body  110 . The other end of the filler neck  12  is provided with a filler neck opening  121 . The filler neck  12  communicates the tank inner space  111  and an outside of the tank body  110 . The filler neck  12  is formed to be located at a vertically elevated position relative to the tank body  110 , that is, at an upper side of the tank body  110 , under a state that the fuel tank  11  is mounted in the vehicle  1 . The filler neck  12  is formed to receive a gas pump nozzle  100 . The fuel is supplied to the tank inner space  111  of the fuel tank  11  through the filler neck  12  from the gas pump nozzle  100  inserted into the filler neck opening  121 . The filler neck opening  121  is normally closed with a tank cap (not shown), which opens and closes the filler neck opening  121 . 
     The tank body  110  has a tank opening  14 . The tank opening  14  is formed to communicate the tank inner space  111  with an external part of the tank body  110 . The tank opening  14  is formed at a vertically elevated position (upside) relative to the tank body  110 , that is, at an upper side of the tank body  110 , under a state that the fuel tank  11  is mounted in the vehicle  1 . The fuel stored in the fuel tank  11  evaporates and generates evaporated fuel in the tank inner space  111 . 
     The fuel tank system  10  includes a tank passage  21 , a purge passage  22 , an atmosphere passage  23 , a purge valve  41 , a canister  30 , an electric control valve  70 , an electronic control unit (herein referred to as ECU)  50 , a fuel level sensor  60  and the like. 
     The tank passage  21  is provided with its one end being connected to the tank opening  14  of the fuel tank  11 . Thus, the tank passage  21  is communicated with the tank inner space  111  of the fuel tank  11  through the tank opening  14 . The evaporated fuel generated in the fuel tank  11  flows into the tank passage  21  through the tank opening  14 . 
     The canister  30  includes a case  31 , an adsorbent  32  and the like. The case  31  is made of resin and formed in a box shape for example. The casing  31  is provided with case openings  311 ,  312  and  313 . The case openings  311 ,  312  and  313  are formed to communicate an inside and an outside of the case  31 . 
     The adsorbent  32  is provided inside the case  31 . The case opening  311  and the case opening  312  are formed at positions opposite to the case opening  313  relative to the adsorbent  32  in the case  31 . The adsorbent  32  is located to be closer to the case opening  313  in an inner space of the case  31 . As a result, a space  33  is provided in the case  31  at a part closer to the case openings  311  and  312 . The case opening  311  is thus communicated with the case opening  312  through the space  33 . As a result, an airflow resistance in the space  33  of the canister  30  between the case opening  311  and the case opening  312  is almost zero, that is, smaller than a predetermined value. 
     The case opening  311  of the canister  30  is connected to the other end of the tank passage  21 . Thus the other end of the tank passage  21  is communicated to the inside of the case  31  through the case opening  311 . As a result, the evaporated fuel generated in the fuel tank  11  flows into the inside of the case  31  (space  33 ) of the canister  30  through the tank opening  14  of the fuel tank  11 , the tank passage  21  and the case opening  311 . 
     The adsorbent  32  is activated carbon or the like, for example, which is capable of adsorbing the evaporated fuel. The adsorbent  32  thus adsorbs the evaporated fuel, which generates in the fuel tank  11  and flows into the inside (space  33 ) of the case  31  through the case opening  311 . 
     One end of the purge passage  22  is connected to the case opening  312  of the canister  30  and the other end of the purge passage  22  is connected to an opening of the intake pipe  3 . Thus the one end of the purge passage  22  is communicated with the inside (space  33 ) of the case  31  of the canister  30  through the case opening  312 . The other end of the purge passage  22  is communicated with the intake passage  4  through the opening of the intake pipe  3 . With this configuration, the evaporated fuel in the space  33  of the canister  30  is led to the intake passage  4  through the purge passage  22 . 
     One end of the atmosphere passage  23  is connected to the case opening  313  of the canister  30  and the other end of the atmosphere passage  23  is open to the atmosphere. Thus one end of the atmosphere passage  23  is communicated to the inside of the case  31  through the case opening  313 . 
     The evaporated fuel entering into the case  31  through the case opening  311  passes through the adsorbent  32  in flowing to the case opening  313 . The evaporated fuel is adsorbed by the adsorbent  32  while flowing toward the case opening  313 . As a result, the evaporated fuel contained in air flowing out from the atmosphere passage  23  to the atmosphere side is lower than a predetermined concentration. 
     The purge valve  41  is provided in the purge passage  22  to open and close the purge passage  22 . In the first embodiment, the purge valve  41  is a valve device of a normally-closed type, which remains in a closed valve state when no current is supplied. 
     The electric control valve  70  is provided in the tank passage  21 . In the first embodiment, the electric control valve  70  is located at a position, which is separated from the fuel tank  11  and the canister  30  by predetermined distances. The electric control valve  70  includes a valve member  71  and an electromagnetic driving part  72 . The valve member  71  is formed in a rod shape or a plate shape, for example, and provided to be reciprocally movable in an axial direction or in a planar direction. The valve member  71  is capable of variably regulating an open rate of the tank passage  21  in correspondence to a position of its top end part in the tank passage  21 . Here, the open rate means a ratio of flow passage area relative to a total cross sectional area of the tank passage  21 . The open rate is 0, when the tank passage  21  is closed. The open rate is 1, when the tank passage  21  is fully open. The electromagnetic driving part  72  includes an electromagnetic coil, which generates electromagnetic force to reciprocally move the valve member  71  in response to supply and interruption of current. The electromagnetic driving part  72  is thus capable of regulating the position of the valve member  71  in the tank passage  21  thereby to regulate the open rate of the tank passage  21 . In the first embodiment, the electric control valve  70  is a solenoid valve. 
     When no current is supplied to the electromagnetic driving part  72 , the open rate of the tank passage  21  determined by the electric control valve  70  is 0. In the following description, a part of the tank passage  21  located at the fuel tank  11  side relative to the valve member  71  is referred to as a tank-side passage  211  and the other part of the tank passage  21  located at the canister  30  side relative to the valve member  71  is referred to as a canister-side passage  212 . 
     The ECU  50  is a small computer, which includes a CPU as an arithmetic logic unit, ROM, RAM and EEPROM as storage means, and an I/O as input-output circuit and the like. The ECU  50  executes calculations, which are defined by programs stored in the ROM and the like, by using information such as signals received from various sensors provided at various locations in the vehicle  1  and controls operations of various equipment and devices of the vehicle  1 . The ECU  50  thus executes the programs stored in a non-transitive storage medium. By the execution of the programs, methods defined by the programs are attained. The ECU  50  includes, as conceptually functional parts, a control part  51 , a fill-up detection part  52  and a refill detection part  53 . A part or all of the functions, which the ECU  50  executes, may be performed by hardware using one or multiple integrated circuits. That is, the functions provided by the ECU  50  may be attained by software, hardware or combination of software and hardware. 
     The control part  51  is configured to control the operations of the throttle valve  5 , the fuel pump  6 , the fuel injection valve and the like based on information such as signals from the sensors. The control part  51  controls the amount of intake air taken into the engine  2 , the amount of fuel supplied from the fuel tank  11  to the fuel injection valve and the amount of fuel supplied from the fuel injection valve into the engine  2 . The control part  51  further controls the operation of the purge valve  41 . For this reason, the control part  51  controls the opening and closing of the purge passage  22 . 
     When the engine  2  is in operation, for example, that is when the air flows through the intake passage  4 , the control part  51  controls the operation of the purge valve  41  to open the purge passage  22  upon estimation that the amount of evaporated fuel adsorbed in the canister  30  reached a predetermined value. Thus, vacuum pressure arises in the intake passage  4 . As a result, the evaporated fuel adsorbed in the adsorbent  32  and present in the space  33  of the canister  30  are discharged into the intake passage  4  through the purge passage  22 . The control part  51  thus controls the operation of the purge valve  41  to purge the evaporated fuel into the intake passage  4 . 
     The control part  51  further controls the operation of the electric control valve  70 . The control part  51  controls the open rate of the tank passage  21  by the valve member  71  by controlling current supply to the electromagnetic driving part  72  of the electric control valve  70 . 
     The fuel level sensor  60  includes a detection part  61 , an arm  62  and a float  63 . The detection part  61  is provided at an elevated position in the vertical direction relative to a tank inner space  111 . The arm  62  is provided to extend from the detection part  61  in the vertically downward direction. The arm  62  is rotatable about the detection part  61  as a center of rotation. The float  63  is attached to an end part of the arm  62 , which is opposite to the detection part  61 . The float  63  generates buoyant force in the fuel. Thus the float  63  moves vertically in the upward direction in the tank body  110  in correspondence to a level of the fuel remaining in the tank body  110 . At this time, the arm  62  rotates about the detection part  61  as the center of rotation. 
     The detection part  61  detects a rotational position of the arm  62 . The detection part  61  outputs the signal corresponding to the detected rotational position of the arm  62  to a fill-up detection part  52  of the ECU  50 . The fill-up detection part  52  detects the fuel level in the tank body  110  based on the signal received from the detection part  61 . Thus the fill-up detection part  52  checks whether the tank body  110  is filled up with fuel. That is, the fill-up detection part  52  detects that the fuel is filled up in the fuel tank  11  based on the signal from the fuel level sensor  60 , that is, based on fuel surface position in the fuel tank  11 . 
     The fuel tank system  10  further includes a lid  13 , a lid manipulation switch  15 , a lid manipulation device  16  and a lid open/close sensor  501 . The lid  13  is provided on an outer wall of the vehicle  1  to cover a filler neck opening  121  together with the tank cap. The lid manipulation switch  15  is provided inside the vehicle  1  to be manipulated by a driver of the vehicle  1 . The lid manipulation device  16  is configured to open and close the lid  13 . When the driver manipulates the lid manipulation switch  15 , the lid manipulation device  16  opens the lid  13 . After the tank cap is removed, refilling the fuel tank  11  with fuel is enabled. 
     The lid open/close sensor  501  detects an open/close state of the lid and outputs a signal, which indicates this detected state, to the refill detection part  53  of the ECU  50 . Based on the signal received from the lid open/close sensor  501 , the refilling detection part  53  detects that refilling of fuel is started when the lid  13  is opened from the closed state. Based on the signal received from the lid open/close sensor  501 , the refilling detection part  53  detects that refilling of fuel is finished when the lid  13  is closed from the open state. Thus, the refilling detection part  53  detects refilling the fuel tank  11  with fuel. 
     When the lid  13  is opened from the closed state, that is, when the refilling detection part  53  detects that the refilling is started, the control part  51  controls the electric control valve  70  to open toward a larger open rate. As a result, the electric control valve  70  is maintained in the open state during a period of refilling the fuel tank  11  with fuel. Thus the fluid in the fuel tank  11  is allowed to flow toward the canister  30  through the tank passage  21 . The fuel is thus supplied to the fuel tank  11  smoothly from the gas pump nozzle  100 . 
     When the fill-up detection part  52  detects that the fuel is filled up in the fuel tank  11  while refilling of fuel is being detected by the refill detection part  53 , the control part  51  controls the electric control valve  70  to close toward a small open rate. In the first embodiment, the control part  51  decreases the open rate of the tank passage  21  by the electric control valve  70  to 0. Thus the tank passage  21  is closed. 
     In case that refilling the fuel tank  11  with fuel is continued even after the tank passage  21  is closed by the electric control valve  70 , the inner pressure of the fuel tank  11  increases rapidly. In case that the gas pump nozzle  100  includes a pressure sensor therein, the gas pump nozzle  100  automatically stops refilling when the pressure sensor detects a rise of the inner pressure of the fuel tank  11 . In case that the gas pump nozzle  100  includes a fuel level sensor therein, the gas pump nozzle  100  automatically stops refilling when the fuel level sensor detects a fuel level in the fuel supply pipe  12 . 
     As described above, the fuel tank system  10  according to the first embodiment includes the tank passage  21 , the canister  30 , the electric control valve  70 , the fill-up detection part  52  and the control part  51 . One end of the tank passage  21  is connected to the fuel tank  11 , which stores fuel. The canister  30  is connected to the other end of the tank passage  21  and adsorbs the evaporated fuel generated by evaporation of fuel in the fuel tank  11 . The electric control valve  70  is operable with current supply to control the amount of fluid flowing through the tank passage  21  by varying the open rate of the tank passage  21 . The fill-up detection part  52  detects that the fuel tank  11  is filled up with fuel based on the fuel level in the fuel tank  11  without detecting the inner pressure of the fuel tank  11 . The control part  51  controls the operation of the electric control valve  70 . 
     According to the first embodiment, the control part  51  controls the electric control valve  70  in the valve closing direction, which decreases the open rate of the tank passage  21 , when the fill-up detection part  52  detects that the fuel tank  11  is filled up with fuel. As a result, the amount of fluid flowing through the tank passage  21  decreases. The fluid flowing through the tank passage  21  is not the liquid fuel but the evaporated fuel. 
     Thus, even when the fuel is supplied further into the fuel tank  11  after the fuel tank  11  is filled up with fuel, the fuel and the evaporated fuel are restricted from flowing to the canister  30  side through the tank passage  21 . According to the first embodiment, the fill-up detection part  52  detects that the fuel tank  11  is filled up with fuel without detecting the pressure present in the fuel tank  11 . As a result, it is possible to appropriately control the amount of fluid flowing through the tank passage  21  at the time of fill-up of fuel in the fuel tank  11  in a simple configuration without using the conventionally-used float valve and pressure sensor. 
     Further, according to the first embodiment, when the fill-up detection part  52  detects that the fuel is filled up, the control part  51  controls the electric control valve  70  in the valve closing direction toward the open rate of the tank passage  21  to 0. Thus, when the fuel is filled up, the tank passage  21  is surely closed. As a result, even when the fuel is supplied further into the fuel tank  11  after the fuel tank  11  is filled up with fuel, the fuel and the evaporated fuel are restricted from flowing to the canister  30  side through the tank passage  21 . 
     Still further, according to the first embodiment, the electric control valve  70  includes the valve member  71 , which varies the open rate of the tank passage  21 , and the electromagnetic driving part  72 , which drives the valve member  71  to vary the open rate of the tank passage  21 . As a result, the electric control valve  70  is configured comparatively simply. Further, the electric control valve  70  is controlled comparatively simply. 
     Second Embodiment 
     A fuel tank system according to a second embodiment is shown in  FIG. 2 . In the second embodiment, a concentration sensor  502  is provided additionally. Further, the ECU  50  includes a breakthrough prediction part  54  additionally. 
     The concentration sensor  502  is provided to the canister  30 . The concentration sensor  502  detects a concentration of the evaporated fuel in the canister  30  and outputs a signal indicating a detected concentration to the breakthrough detection part  54  of the ECU  50 . The breakthrough detection part  54  detects a breakthrough of the canister  30  or predicts a breakthrough time of the canister  30  based on the signal received from the concentration sensor  502 . The breakthrough of the canister  30  means that the evaporated fuel adsorbed by the canister  30  reached a maximum value of evaporated fuel adsorption of the canister  30 . 
     When the breakthrough detection part  54  detects the breakthrough of the canister  30  or predicts the breakthrough which will occur after a certain time lapse, the control part  51  controls the electric control valve  70  in the valve closing direction. Thus, the evaporated fuel is restricted from flowing into the canister  30  through the tank passage  21  and being discharge in the atmosphere through the canister  30 , which is in the breakthrough state. 
     In the second embodiment, even in the course of refilling of the fuel tank  11 , the control part  51  controls the electric control valve  70  to operate in the valve closing direction upon detection of the breakthrough or prediction of the coming breakthrough of the canister  30 . Thus the flow amount of the fluid flowing through the tank passage  21  decreases. In the second embodiment, the open rate of the tank passage  21  is decreased to 0 so that the tank passage  21  is closed. 
     When the fuel is refilled into the fuel tank  11  continuously even after the closure of the tank passage  21 , the inner pressure of the fuel tank  11  rises rapidly. In case of the gas pump nozzle  100  having the pressure sensor, refilling of the fuel from the gas pump nozzle  100  is stopped automatically when the pressure sensor detects a rise of the inner pressure of the fuel tank  11 . The second embodiment has the additional configuration and operation described above in addition to the configuration and operation of the first embodiment. 
     As described above, according to the second embodiment, the breakthrough detection part  54  is provided additionally. The breakthrough detection part  54  detects the breakthrough of the canister  30  or predicts the possible breakthrough time of the canister  30 . The control part  51  controls the electric control valve  70  to operate in the valve closing direction upon detection of the breakthrough or prediction of the coming breakthrough of the canister  30 . Thus the flow amount of the fluid flowing through the tank passage  21  decreases. When the fuel is refilled into the fuel tank  11  continuously even after the closure of the tank passage  21 , the inner pressure of the fuel tank  11  rises rapidly. In case of the gas pump nozzle  100  having the pressure sensor, refilling of the fuel from the gas pump nozzle  100  is stopped automatically when the pressure sensor detects the rise of the inner pressure of the fuel tank  11 . Thus it is possible to stop refilling the fuel tank  11  before the evaporated fuel is discharged into the atmosphere through the canister  30 . 
     Third Embodiment 
     A fuel tank system according to a third embodiment is shown in  FIG. 3 . In the third embodiment, the electric control valve  70  is located at a position different from that in the first embodiment. In the third embodiment, the electric control valve  70  is provided at the end part of the tank passage  21 , which is at the fuel tank  11  side. The electric control valve  70  is attached in contact with an outer wall of the tank body  110  of the fuel tank  11 . In comparison to the first embodiment, a volume of the tank-side passage  211  of the tank passage  21  is small. The third embodiment has the additional configuration and operation described above in addition to the configuration and operation of the first embodiment. 
     In the third embodiment, the electric control valve  70  is provided at the end part of the tank passage  21 , which is at the fuel tank  11  side. As a result, the volume of the tank-side passage  211  of the tank passage  21  is decreased. When the fuel is refilled into the fuel tank  11  continuously even after the closure of the tank passage  21 , the inner pressure of the fuel tank  11  rises rapidly. In case of the gas pump nozzle  100  having the pressure sensor, refilling of the fuel from the gas pump nozzle  100  is stopped automatically when the pressure sensor detects the rise of the inner pressure of the fuel tank  11 . 
     Fourth Embodiment 
     A fuel tank system according to a fourth embodiment is shown in  FIG. 4 . In the fourth embodiment, an electric control valve  80  is provided in the tank passage  21  in place of the electric control valve  80 . The electric control valve  80  is configured and controlled differently from the electric control valve  70  in the first embodiment. In the fourth embodiment, the electric control valve  80  is located at a position separated from the fuel tank  11  and the canister  30  by predetermined distances. The electric control valve  80  includes a valve member  81  and a motor  82 . 
     The valve member  81  is formed in a rod shape or a plate shape and reciprocally movable in the axial direction or planar direction. The valve member  81  regulates the open rate of the tank passage  21  in accordance with a position of its top end part in the tank passage  21 . The motor  82  is driven with current supply to regulate the position of the valve member  81 . Thus the motor  82  regulates the open rate of the tank passage  21  by way of the valve member  81 . 
     The control part  51  controls the open rate of the tank passage  21  by the valve member  81  by controlling the current supplied to the motor  82 . The control part  51  stops the valve member  81  at an arbitrary position by interrupting the current supply to the motor  82 . 
     An exemplary operation of the fuel tank system  10  according to the fourth embodiment will be described next. As indicated by a solid line in  FIG. 5 , when the refill detection part  53  detects the start of refilling of fuel at time t 1 , the control part  51  controls the electric control valve  80  to operate in the opening direction to increase the open rate of the tank passage  21 . The open rate of the tank passage  21  thus reaches 1 at time t 2 . As a result, the inner pressure of the fuel tank  11 , that is, tank inner pressure, decreases. The tank inner pressure thus decreases to about the atmospheric pressure at time t 3 . 
     When the fill-up detection part  52  detects that the fuel is filled up at time t 4  as a result of continuation of refilling of fuel during a period between time t 3  and time t 4  after the start of refilling at time t 1 , for example, the control part  51  controls the electric control valve  80  to operate in the valve closing direction to decrease the open rate of the tank passage  21 . In the fourth embodiment, when the fill-up detection part  52  detects that the fuel is filled up to a maximum level at time t 4 , the control part  51  controls the electric control valve  80  in the valve closing direction thereby to regulate the open rate of the tank passage  21  to a predetermined open rate. The predetermined open rate is larger than 0 and smaller than a maximum open rate of the tank passage  21 , that is, it is about an open rate, which allows a predetermined amount of the fluid flowing through the tank passage  21  under the refilling state to flow and the tank inner pressure to rise. In the fourth embodiment, for example, the predetermined open rate corresponds to a flow amount of fluid of about 5 liters per minute (l/m) or less, which flows in the tank passage  21  under the refilling state. The flow amount of the fluid, which flows in the tank passage  21  in the maximum open rate under refilling of fuel by the gas pump nozzle  100 , is generally about 40 liters per minute (l/m). The fluid, which flows in the tank passage  21 , is not the liquid fuel but the evaporated fuel. 
     When the open rate of the tank passage  21  is decreased to the predetermined open rate, the tank inner pressure gradually increases thereafter and remains at a constant level after reaching the constant level at time t 8 . When the pressure sensor provided in the gas pump nozzle  100  detects the rise of the inner pressure of the fuel tank  11  between time t 5  and time t 8 , the gas pump nozzle  100  automatically stops refilling of fuel. 
     An advantageous effect of the fourth embodiment will be described below in comparison to an exemplary operation of a fuel tank system according to a comparison example, which is indicated by a dotted line in  FIG. 5 . The fuel tank system according to the comparison example is configured similarly to that of the fourth embodiment. However, the control part  51  controls the electric control valve  80  differently from that of the fourth embodiment. In the fuel tank system according to the comparison example, when the fill-up detection part  52  detects the fill-up of the fuel at time t 4 , the control part  51  controls the electric control valve  80  to operate in the valve closing direction and decreases the open rate of the tank passage  21  to 0 at time t 6 . The tank inner pressure thus rapidly rises after time t 6  and overshoots at time t 7 . As a result, the fuel is likely to spill over the refill opening  121  of the filler neck  12 . 
     In the fourth embodiment described above, when the fill-up detection part  52  detects the fill-up of fuel at time t 4 , the control part  51  controls the electric control valve  80  to operate in the valve closing direction to the predetermined open rate at time t 5 . As a result, the tank inner pressure rises slowly thereafter. It is thus possible to suppress overshooting of the tank inner pressure, which arises in the comparison example, and prevent the fuel from spilling over the fuel refill opening  121  of the filler neck  12 . 
     As described above, according to the fourth embodiment, when the fill-up detection part  52  detects the fill-up of fuel in the fuel tank, the control part  51  controls the electric control valve  80  to operate in the valve closing direction so that the open rate of the tank passage  21  is regulated to the predetermined open rate, which is larger than 0 but smaller than the maximum open rate. By setting the predetermined open rate to a rate, which allows the predetermined amount of fluid to flow through the tank passage  21  under the fuel refilling state and the tank inner pressure to rise, the tank inner pressure is increased while preventing the overflow of fuel from the fuel refill opening  121 . In case that the gas pump nozzle  100  is provided with the pressure sensor, the gas pump nozzle  100  automatically stops refilling of fuel upon detection of the rise of the inner pressure of the fuel tank  11 . 
     In addition, according to the fourth embodiment, the electric control valve  80  includes the valve member  81 , which varies the open rate in the tank passage  21 , and the motor  82 , which drives the valve member  81  to vary the open rate with the current supply. The control part  51  thus stops the valve member  81  at the arbitrary position by interrupting the current supply to the motor  82 . As a result, it is possible to precisely control the open rate of the tank passage  21  to the predetermined open rate by the electric control valve  80 . For stopping the electric control valve  80  at the predetermined open rate of the tank passage  21 , the current supply to the electric control valve  80  is interrupted. As a result, power consumption of the electric control valve  80  is decreased. 
     Fifth Embodiment 
     A fuel tank system according to a fifth embodiment will be described with reference to  FIG. 6 . In the fifth embodiment, the electric control valve is controlled differently from that of the fourth embodiment. The fuel tank system is configured similarly to that of the fourth embodiment. In the fifth embodiment, however, the control part  51  controls current supply to the motor  82  to control a moving speed of the valve member  81 . 
     An exemplary operation of the fuel tank system  10  according to the fifth embodiment will be described below. As indicated by a solid line in  FIG. 6 , when the refill detection part  53  detects the start of refilling of fuel at time t 1 , the control part  51  controls the electric control valve  80  to operate in the opening direction to increase the open rate of the tank passage  21 . The open rate of the tank passage  21  thus reaches 1 at time t 2 . As a result, the inner pressure of the fuel tank  11 , that is, tank inner pressure, decreases. The tank inner pressure thus decreases to about the atmospheric pressure at time t 3 . 
     When the fill-up detection part  52  detects that the fuel is filled up at time t 4  as a result of continuation of refilling of fuel during the period between time t 3  and time t 4  after the start of fuel refilling at time t 1 , for example, the control part  51  controls the electric control valve  80  to operate in the valve closing direction to decrease the open rate of the tank passage  21 . In the firth embodiment, the control part  51  controls the electric control valve  80  in the valve closing direction thereby to decrease the open rate of the tank passage  21  gradually. As a result of gradual decrease in the open rate of the tank passage  21  from time t 4  to time t 7 , the open rate of the tank passage  21  is decreased finally to 0. In the fifth embodiment, the period from time t 4  to time t 7  is about 50 milliseconds (ms). That is, the control part  51  varies the open rate of the tank passage  21  from 1 to 0 during the period of about 50 ms. 
     As a result of control of the control part  51  for the electric control valve  80 , the tank inner pressure gradually rises from time t 5  to time t 7  and remains to be the same after time t 7 . When the pressure sensor provided in the gas pump nozzle  100  detects the rise of the inner pressure of the fuel tank  11  between time t 5  and time t 7 , refilling of fuel by the gas pump nozzle  100  is stopped automatically. 
     An advantageous effect of the fifth embodiment will be described below in comparison to an exemplary operation of a fuel tank system according to a comparison example, which is indicated by a dotted line in  FIG. 6 . The fuel tank system according to the comparison example is configured similarly to that of the fifth embodiment. However, the control part  51  controls the electric control valve  80  differently from that of the fifth embodiment. In the fuel tank system according to the comparison example, when the fill-up detection part  52  detects the fill-up of the fuel at time t 4 , the control part  51  controls the electric control valve  80  to operate in the valve closing direction and decreases the open rate of the tank passage  21  to 0 at time t 5 . The predetermined period is about 30 ms to 40 ms, for example. The tank inner pressure thus rapidly rises after time t 5  and overshoots at time t 6 . As a result, the fuel is likely to spill over the refill opening  121  of the filler neck  12 . 
     In the fifth embodiment described above, when the fill-up detection part  52  detects the fill-up of fuel at time t 4 , the control part  51  controls the electric control valve  80  to operate in the valve closing direction to the predetermined open rate at time t 5 . As a result, the tank inner pressure rises slowly after time t 5 . It is thus possible to suppress overshooting of the tank inner pressure, which arises in the comparison example, and prevent the fuel from spilling over the fuel refill opening  121  of the filler neck  12 . 
     As described above, according to the fifth embodiment, when the fill-up detection part  52  detects the fill-up of fuel in the fuel tank, the control part  51  controls the electric control valve  80  to operate in the valve closing direction so that the open rate of the tank passage  21  is regulated to gradually decrease. When the refilling of fuel is continued even after the fill-up of fuel in the fuel tank under the fuel refilling state, the tank inner pressure increases gradually. As a result, the tank inner pressure is increased while preventing the overflow of fuel from the fuel refill opening  121 . In case that the gas pump nozzle  100  is provided with the pressure sensor, the gas pump nozzle  100  automatically stops refilling of fuel upon detection of the rise of the inner pressure of the fuel tank  11  by the pressure sensor. 
     Sixth Embodiment 
     A fuel tank system according to a sixth embodiment is shown only partly in  FIG. 7  and  FIG. 8 . In the sixth embodiment, the fuel tank system includes an electric control valve  90 , which is configured differently from that of the first embodiment. The electric control valve  90  is provided in the tank passage  21 . In the sixth embodiment, the electric control valve  90  is located at a position separated from the fuel tank  11  and the canister  30  by predetermined distances. The electric control valve  90  includes a main chamber  91 , a back-pressure chamber  92 , a pressure valve  93 , a spring  94 , an electromagnetic valve  95 , a throttle part  96  and the like. 
     The main chamber  91  is formed at an end part, which is at the canister-side passage  212  of the tank-side passage  211 . The main chamber  91  is formed annularly around a circumference of the end part, which is at the tank-side passage  211  side of the canister-side passage  212 . A valve seat  251  is formed at an end part, which is at the tank-side passage  211  of the canister-side passage  212 . The back-pressure chamber  92  is provided adjacently to the main chamber  91 . The back-pressure chamber  92  and the tank-side passage  211  are connected by a first bypass passage  201 . The back-pressure chamber  92  and the canister-side passage  212  are connected by a second bypass passage  202 . A valve seat  252  is formed in a middle of the second bypass passage  202 . 
     The pressure valve  93  is provided between the main chamber  91  and the back-pressure chamber  92 . The pressure valve  93  is formed of a valve member  931  and a diaphragm  932 . The valve member  931  is made of an elastic material such as rubber and formed in a plate shape. The diaphragm  932  is made of an elastic material such as rubber and formed in a thin plate shape. The diaphragm  932  is provided to partition the main chamber  91  and the back-pressure chamber  92 . The valve member  931  is provided on a surface of the diaphragm  932 , which is on the main chamber  91  side. A surface of the valve member  931 , which is on an opposite side to the diaphragm  932 , is movable to contact the valve seat  251  and leave from the valve seat  251 . 
     The spring  94  is provided in the back-pressure chamber  92 . The spring  94  is a coil spring and biases the pressure valve  93  such that the valve member  931  is pressed to the valve seat  251 . When a pressure in the main chamber  91  is higher than that of the back-pressure chamber  92 , the diaphragm  932  deforms in a direction to leave from the valve seat  251  against the biasing force of the spring  94 . The valve member  931  thus leaves from the valve seat  252 . 
     When the valve member  931  is in contact with the valve seat  251 , the open rate of the tank passage  21  (pressure valve  93 ) in the tank passage  21  is 0. At this time, the tank-side passage  211  and the canister-side passage of the tank passage  21  are closed. As the valve member  931  leaves from the valve seat  251 , the open rate of the tank passage  21  (pressure valve  93 ) in the tank passage  21  increases. 
     The electromagnetic valve  95  is formed of a valve member  951 , a shaft part  952 , an electromagnetic driving part  953  and a spring  954 . The valve member  951  is made of an elastic material such as rubber and formed in a plate shape. The valve member  951  has a surface, which is movable to contact the valve seat  252  and leave from the valve seat  252 . The shaft part  952  is formed in a rod shape, which extends from the valve member  951  toward a side opposite to the valve seat  252 . The shaft part  952  is reciprocally movable in an axial direction together with the valve member  951 . The electromagnetic driving part  953  has a coil, for example, to generate magnetic force in response to current supply and reciprocally move the valve member  951  and the shaft part  952  in the axial direction. The electromagnetic driving part  953  varies the open rate of the second bypass passage  202  by the valve member  951 . In the sixth embodiment, the electromagnetic valve  95  is a solenoid valve. The spring  954  is a coil spring, which biases the valve member  951  and the shaft part  952  such that the valve member  951  is pressed to the valve seat  252 . 
     In response to the current supply to the electromagnetic driving part  953 , the valve member  951  and the shaft part  952  move toward a position opposite to the valve seat  252  against the biasing force of the spring  954 . Thus the valve member  951  leaves from the valve seat  252 . Thus the electromagnetic valve  95  operates with the current supply to open and close the second bypass passage  202 , that is, the passage part between the back-pressure chamber  92  and the canister  30 . When no current is supplied to the electromagnetic valve  95 , the valve member  951  contacts the valve seat  252  and shuts down the passage between the back-pressure chamber  92  and the canister  30 . The biasing force of the spring  954  is set to be comparatively small. For this reason, even in case that the electric current supplied to the electromagnetic valve  95  is comparatively small, the valve member  951  is enabled to leave from the valve seat  252  to open the second bypass passage  202 . 
     The throttle part  96  is provided in the first bypass passage  201 . The throttle part  96  is formed circularly so that its inner diameter is smaller than that of the first bypass passage  201 . That is, the throttle part  96  restricts the fluid from flowing in the first bypass passage  201 . For this reason, when a pressure difference arises between the tank-side passage  211  side and the back-pressure chamber  92  side in the first bypass passage  201 , the fluid flows through the throttle part  96  slowly. Thus the pressure difference between the tank-side passage  211  side and the back-pressure chamber  92  side in the first bypass passage  201  is decreased slowly as time lapses. 
     The control part  51  controls the open rate of the pressure valve  93  by controlling the current supply to the electromagnetic valve  95 . For example, when the fuel evaporates in the fuel tank  11  under a state that the electromagnetic valve  95  closes the back-pressure chamber  92  and the canister  30 , pressures in the tank-side passage  211  of the tank passage  21 , the main chamber  91 , the first bypass passage  201  and the back-pressure chamber  92  become higher than the atmospheric pressure. When the control part  51  controls the current supply to the electromagnetic valve  95  so that the valve member  951  leaves from the valve seat  252  as shown in  FIG. 8 , the pressure in the back-pressure chamber  92  becomes generally equal to the atmospheric pressure similarly to the pressure in the canister-side passage  212  of the tank passage  21 . Thus the pressure in the back-pressure chamber  92  becomes negative relative to that of the main chamber  91 . The diaphragm  932  deforms such that the valve member  931  leaves from the valve seat  251 . As a result, the fluid in the tank-side passage  211  flows to the atmosphere side through the valve seat  251 , the canister-side passage  212 , the canister  30  and the atmospheric passage  23 . The tank inner pressure correspondingly falls. Since the throttle part  96  restricts the fluid flow in the first bypass passage  201 , the valve member  931  continues to be separated away from the valve seat  251  for a predetermined period. 
     In the sixth embodiment, when the lid  13  is changed from the closed state to the open state, that is, when the refill detection part  53  detects the start of refilling of fuel into the fuel tank  11 , the control part  51  controls the electromagnetic valve  95  to open the second bypass passage  202  and controls the electric control valve  90  to operate in the valve opening direction to increase the open rate. The pressure valve  93  of the electric control valve  90  thus remains to be open as shown in  FIG. 8  during the refilling of fuel into the fuel tank  11 . As a result, the fluid in the fuel tank  11  is allowed to flow to the canister  30  side through the tank passage  21 . It is thus possible to supply the fuel smoothly from the gas pump nozzle  100  into the fuel tank  11 . 
     When the fill-up detection part  52  detects that the fuel is filled up in the fuel tank  11  during a period that the refilling detection part  53  continues detection of the refilling of fuel by the refilling detection part  53 , the control part  51  controls the electromagnetic valve  95  to close the second bypass passage  202  and controls the electric control valve  90  to operate in the valve closing direction to decrease the open rate of the tank passage  21 . As a result, the valve member  931  of the pressure valve  93  contacts the valve seat  251  and so that communication between the tank-side passage  211  and the canister-side passage  212  of the tank passage  21  is interrupted as shown in  FIG. 7 . 
     According to the sixth embodiment described above, the electric control valve  90  includes the main chamber  91 , which is formed in the tank passage  91  and communicated with the fuel tank  11 , the back-pressure chamber  92 , which is formed in the tank passage  21  and communicated with the fuel tank  11  and the canister  30 , the pressure valve  93 , which varies the open rate of the tank passage  21  with the pressure difference between the main chamber  91  and the back-pressure chamber  92 , and the electromagnetic valve  95 , which operates with current supply to open and close the passage between the back-pressure chamber  92  and the canister  30 . As a result, when the back-pressure chamber  92  and the canister  30  are communicated through the electromagnetic valve  95  under the state that the pressures in the main chamber  91  and the back-pressure chamber  92  are higher than the atmospheric pressure, the pressure in the back-pressure chamber  92  side becomes lower relative to that in the main chamber  91  so that the pressure valve  93  is opened. The electromagnetic valve  95  can separate the valve member  951  from the valve seat  252  with small electric current supply. Thus power consumption of the electric control valve  90  is decreased and hence the electromagnetic valve  95  and the electric control valve  90  are configured to be small. 
     Other Embodiment 
     In the first embodiment, the control part  51  is exemplified to control the electric control valve  70  in the valve closing direction to decrease the open rate of the tank passage  21  to 0, when the fill-up detection part  52  detects the fill-up of fuel under the state that the refill detection part  53  detects the refilling. As the other embodiment of the fuel tank system  10 , the control part  51  may be configured to control a duty ratio of electric power supplied to the electromagnetic driving part  72  of the electric control valve  70  to regulate the open rate of the tank passage  21  to the predetermined open rate, when the fill-up detection part  52  detects the fill-up of fuel. This embodiment also provides the same advantages as the fourth embodiment. Similarly, in the sixth embodiment, the control part  51  may be configured to control a duty ratio of electric power supplied to the electromagnetic driving part  953  of the electric control valve  90  to regulate the open rate of the pressure valve  93  of the electric control valve  90  to the predetermined open rate, when the fill-up detection part  52  detects the fill-up of fuel. 
     Further, as the other embodiment of the fuel supply system  10 , the control part  51  may be configured to control a duty ratio of electric power supplied to the electromagnetic driving part  72  of the electric control valve  70  to gradually decrease the valve closing direction in case of operating the electric control valve  70  in the valve closing direction, when the fill-up detection part  52  detects the fill-up of fuel. This embodiment also provides the similar advantage as the fifth embodiment. Similarly, in the sixth embodiment, the control part  51  may be configured to control a duty ratio of electric power supplied to the electromagnetic driving part  953  of the electric control valve  90  to control the electric control valve  90  to gradually decrease the open rate of the pressure valve  93 , when the fill-up detection part  52  detects the fill-up of fuel in the fuel tank  11 . 
     In the second embodiment, the breakthrough detection part  54  is exemplified to detect the breakthrough of the canister  30  or predict the breakthrough time of the canister  30  based on the signal outputted from the concentration sensor  502 , which detects the concentration of evaporated fuel in the canister  30 . As the other embodiment of the fuel tank system  10 , the breakthrough detection part  54  may detect the breakthrough of the canister  30  or predict the breakthrough time of the canister based on the signal outputted from the pressure sensor, which detects the pressure in the canister  30 . Further, in the embodiments described above, the fill-up detection part  52  is exemplified to detect the fill-up of fuel in the fuel tank  11  based on the signal outputted from the fluid level sensor  60  provided in the fuel tank  11 . As the other embodiment of the fuel tank system  10 , the fill-up of fuel in the fuel tank  11  may be detected based on the signal outputted from the liquid level sensor  60  (sender gauge) provided in the fuel pump  6 . 
     As the other embodiment of the fuel tank system  10 , the fill-up detection part  52  is not limited to the liquid level sensor  60 , which has the arm  62  and the float  63 , as far as it is possible to detect the liquid level of fuel in the fuel tank  11 . For example, the fill-up of fuel in the fuel tank  11  may be detected based on a signal from an optical sensor, an electric resistance sensor, a float position sensor or the like. The optical sensor detects a fuel level by emitting light onto a fuel surface and detecting a reflectance or refraction index. The electric resistance sensor detects a fuel level by detecting an electric resistance of a resistor. The float position sensor detects a fuel level by detecting a position of a float, which generates a buoyant force of the float in the fuel. As exemplified above, the fuel tank system  10  is not limited to the embodiments described above and may be implemented in a variety of embodiments.