JP2013204510A - Fuel tank system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank system capable of preventing insufficient purge of a canister.SOLUTION: An intake manifold of an engine is connected with a fuel tank 14 through a gas moving pipe 52. Negative pressure from the intake manifold is applied to the fuel tank 14. A canister piping opening/closing valve 58 is closed to apply the negative pressure to the fuel tank 14. When the negative pressure reaches a predetermined value, the canister piping opening/closing valve 58 is opened, and the negative pressure is applied to the canister 40.

Description

  The present invention relates to a fuel tank system.

  As a fuel tank system mounted on an automobile, Patent Document 1 adsorbs the fuel vapor in the fuel tank with activated carbon of the canister and causes the negative pressure from the engine to act directly on the canister and be adsorbed on the canister. A technique for purging the fuel vapor that has been consumed and consuming it in the engine is described.

  However, in the configuration in which the fuel vapor (evaporated fuel) adsorbed on the canister is purged by using the negative pressure of the engine, when the negative pressure of the engine fluctuates, it is difficult to reliably purge, so-called insufficient purge May occur.

JP 2009-74445 A

  In view of the above facts, an object of the present invention is to provide a fuel tank system capable of suppressing a shortage of canister purge.

  According to the first aspect of the present invention, the fuel tank that stores the fuel, the canister that can adsorb the evaporated fuel generated in the fuel tank by the adsorbent, the upper gas layer in the fuel tank, and the engine communicate with each other. A gas moving pipe for moving the gas in the gas layer to the engine by a negative pressure from the engine communicates with the gas layer and the canister in the upper part in the fuel tank, and the gas moves between the gas layer and the canister. And a canister pipe opening / closing valve that opens and closes the canister pipe.

  In this fuel tank system, the gas layer above the fuel tank and the canister are communicated with each other by canister piping. In a state where the canister pipe opening / closing valve is opened, the gas containing the evaporated fuel generated in the fuel tank moves to the canister through the canister pipe, and the evaporated fuel is adsorbed by the adsorbent in the canister.

  The upper gas layer in the fuel tank and the engine are communicated with each other by a gas moving pipe. When the canister piping on-off valve is closed, the gas in the gas layer moves to the engine due to the negative pressure from the engine, and the pressure in the fuel tank decreases. That is, the inside of the fuel tank can be set to a negative pressure.

  When the canister pipe opening / closing valve is opened while negative pressure is accumulated in the fuel tank in this way, the negative pressure in the fuel tank acts on the canister in a short time. Since the canister can be purged without depending on the negative pressure from the engine, the lack of purge can be suppressed.

  According to a second aspect of the present invention, a fuel tank that contains fuel, expansion / contraction means for expanding / contracting the volume of the fuel tank, a canister that can adsorb evaporated fuel generated in the fuel tank with an adsorbent, and the fuel And a canister pipe that allows the gas layer and the canister to communicate with each other, and a canister pipe on-off valve that opens and closes the canister pipe.

  In this fuel tank system, the gas layer above the fuel tank and the canister are communicated with each other by canister piping. In a state where the canister pipe opening / closing valve is opened, the gas containing the evaporated fuel generated in the fuel tank moves to the canister through the canister pipe, and the evaporated fuel is adsorbed by the adsorbent in the canister.

  The volume of the fuel tank can be expanded / contracted by expansion / contraction means. The pressure in the fuel tank is reduced by enlarging the volume of the fuel tank with the canister piping on-off valve closed (sealed state of the fuel tank). That is, the inside of the fuel tank can be set to a negative pressure.

  When the canister pipe opening / closing valve is opened while negative pressure is accumulated in the fuel tank in this way, the negative pressure in the fuel tank acts on the canister in a short time. Since the canister can be purged without depending on the negative pressure from the engine, the lack of purge can be suppressed.

  According to a third aspect of the present invention, in the second aspect of the present invention, the gas layer in the upper part in the fuel tank is connected to the engine to move the gas in the gas layer to the engine by the negative pressure from the engine. Gas movement piping and a movement piping on-off valve for opening and closing the gas movement piping.

  Since the upper gas layer in the fuel tank and the engine communicate with each other through the gas transfer pipe, the negative pressure from the engine is removed from the fuel tank with the canister pipe open / close valve closed and the move pipe open / close valve open. The pressure in the fuel tank can be lowered by acting on the fuel cell.

  In addition, when expanding the volume of the fuel tank by the expansion / contraction means, the tank internal pressure of the fuel tank can be reliably reduced by closing the moving pipe on-off valve.

  According to a fourth aspect of the invention, there is provided a tank internal pressure sensor for detecting a tank internal pressure of the fuel tank according to any one of the first to third aspects, and the tank internal pressure sensor detects the tank internal pressure sensor. The canister piping on-off valve is opened when the tank internal pressure is equal to or less than a preset specified value.

  When the tank internal pressure detected by the tank internal pressure sensor is less than the specified value, that is, when the negative pressure is reliably accumulated in the fuel tank, the canister piping on-off valve is opened, so that the negative pressure is reliably applied to the canister. Can purge the inside of the canister.

  Since the present invention has the above-described configuration, it is possible to suppress the canister from being insufficiently purged.

It is a schematic block diagram which shows the fuel tank system of 1st Embodiment of this invention in the state which the internal pressure sealing valve closed. It is a schematic block diagram which shows the fuel tank system of 1st Embodiment of this invention in the state which the internal pressure blockade valve opened. It is explanatory drawing which shows the tank internal pressure in the fuel tank system of 1st Embodiment of this invention, and the state of the gas in / out of a fuel tank in order to (A)-(E). It is a schematic block diagram which shows the fuel tank system of 2nd Embodiment of this invention in the state which the internal pressure sealing valve closed and the on-off valve opened. It is a schematic block diagram which shows the fuel tank system of 2nd Embodiment of this invention in the state which the internal pressure sealing valve and the on-off valve closed, and expanded the volume of the fuel tank. It is a schematic block diagram which shows the fuel tank system of 2nd Embodiment of this invention in the state which opened the internal pressure sealing valve after expanding the volume of a fuel tank.

  1 and 2 show a fuel tank system 12 according to a first embodiment of the present invention.

  The fuel tank 14 of the fuel tank system 12 is made of resin in the present embodiment, and has a tank upper layer portion 16 and a tank lower layer portion 18. The tank upper layer portion 16 is convex upward, and the tank lower layer portion 18 is convex downward, and these are joined by an annular tank joint portion 19 so that the fuel can be contained inside as a whole (for example, It is formed in a substantially rectangular parallelepiped box shape.

  In the first embodiment, the tank upper layer portion 16 and the tank lower layer portion 18 have a predetermined rigidity and do not easily expand and contract.

  The lower part of the fuel tank 14 is supported by a tank band (not shown). By fixing both ends of the tank band to the floor panel of the vehicle body, the fuel tank 14 is attached to the vehicle body (floor panel) while being supported by the tank band.

  The lower part of the inlet pipe 32 is not connected to the fuel tank 14. An upper end of the inlet pipe 32 is a fuel supply port 36, and a fuel gun is inserted into the fuel supply port 36 so that fuel can be guided to the fuel tank 14 and supplied. The inlet pipe 32 constitutes the oil supply path of the present invention. Depending on the amount of fuel in the fuel tank 14, part of the fuel is also stored in the inlet pipe 32.

  A valve 38 is provided on the tank upper wall 14T of the fuel tank 14 to regulate the full tank liquid level and prevent fuel leakage. When the fuel tank 14 is refueled, the valve 38 is opened until the fuel in the fuel tank 14 reaches the full tank level, and the gas in the fuel tank 14 is discharged to the canister 40 described later. Can be continued. When the fuel in the fuel tank 14 reaches the full tank level, the valve 38 is closed and the gas in the fuel tank 14 is not discharged to the canister 40, so that the fuel supplied rises in the inlet pipe 32, Refueling gun is reached. As a result, the auto-stop mechanism of the fuel gun operates to stop fueling. Further, when the vehicle on which the fuel tank 14 is mounted rolls over, the valve 38 is closed, and the outflow of fuel is suppressed.

  An oil filler port 36 at the upper end of the inlet pipe 32 is opened and closed by a fuel cap 42. A fuel lid 50 is provided on the outer side of the fuel cap 42 on the side panel 48 of the vehicle body.

  The fuel cap 42 closes the inlet pipe 32 in a state where the fuel cap 42 is attached to the fuel filler port 36, and restricts access of the fuel gun to the inlet pipe 32 (oil supply path). On the other hand, when the fuel cap 42 is removed from the fuel filler port 36, the upper part of the inlet pipe 32 (oil supply path) is opened, and access to the fuel supply path becomes possible.

  A canister 40 is disposed above the fuel tank 14. In the canister 40, an adsorbent made of activated carbon or the like is accommodated, and the adsorbent can adsorb and desorb the evaporated fuel. The fuel tank 14 and the canister 40 are communicated with each other through a canister pipe 56.

  A canister pipe opening / closing valve 58 is provided in the middle of the canister pipe 56. The canister pipe opening / closing valve 58 is opened and closed under the control of the ECU 76. When the canister pipe opening / closing valve 58 is closed, the gas containing the evaporated fuel does not flow from the fuel tank 14 to the canister 40. On the other hand, when the canister pipe opening / closing valve 58 is opened, this gas can be moved to the canister 40.

  As the canister piping on-off valve 58, an electric on-off valve, a mechanical on-off valve, an on-off valve using both electric and mechanical methods, and the like can be used. The canister pipe opening / closing valve 58 can be operated as a safety valve that suppresses an excessive increase in internal pressure by opening when the fuel tank 14 is at a high pressure.

  The canister 40 is further provided with an air release pipe 60. The end of the atmosphere release pipe 60 is open to the atmosphere. Therefore, when the canister pipe opening / closing valve 58 is closed, the gas in the fuel tank 14 passes through the canister 40 (at this time, the evaporated fuel is adsorbed by the adsorbent) and then discharged to the atmosphere.

  The fuel tank 14 and an intake manifold (not shown) of the engine are connected by a gas moving pipe 52, and the negative pressure from the intake manifold acts on the fuel tank 14. In particular, in a state where the canister pipe opening / closing valve 58 is closed and the fuel tank 14 is sealed, the inside of the fuel tank 14 is reduced by the negative pressure from the intake manifold. For example, the inside of the fuel tank 14 can be set to a state lower than the atmospheric pressure.

  When the canister pipe opening / closing valve 58 is opened in a state where a predetermined negative pressure is generated in the fuel tank 14 in this manner, the negative pressure in the fuel tank 14 acts on the canister 40. As a result, outside air is introduced from the atmosphere opening pipe 60 to the canister 40, and the evaporated fuel adsorbed on the canister 40 is desorbed (purged) and sent into the fuel tank 14.

  The air release pipe 60 is provided with an air filter 64 that removes foreign matter in the outside air introduced into the canister 40. This foreign matter includes substances that reduce the cross-sectional area of the flow path of the air release pipe 60, such as water and mud, in addition to air and dirt.

  A fuel pump module 66 for sending the internal fuel to the engine is provided in the fuel tank 14. The fuel pump module 66 and the engine are communicated with each other through a fuel supply pipe 68, and the fuel can be sent to the engine by driving a fuel pump 70 that constitutes the fuel pump module 66. Further, the fuel pump module 66 includes a liquid level sensor 72 so that the fuel level in the fuel tank 14 can be detected. The detected liquid level is sent to the ECU 76.

  The fuel pump 70 has an outer cylinder 70G as a pump housing installed on the tank lower wall 14B of the fuel tank 14, and an inner cylinder 70N arranged to be slidable up and down inside the outer cylinder 70G. The upper end of the inner cylinder 70N is joined to the retainer 22 of the tank upper wall 14T. The inner cylinder 70N is slidable up and down with respect to the outer cylinder 70G. Even when the tank lower wall 14B and the tank upper wall 14T are slightly approached or separated from each other, the fuel pump 70 is placed on the tank lower wall 14B at a predetermined position. The installed state can be maintained.

  A tank internal pressure sensor 74 is provided on the tank upper wall 14 </ b> T of the fuel tank 14. The tank internal pressure sensor 74 detects the internal pressure of the fuel tank 14. Information on the detected internal pressure of the fuel tank 14 is sent to the ECU 76.

  The canister 40 is provided with an abnormality detection pump 54. By driving the abnormality detection pump 54, a negative pressure can be generated in the fuel tank 14. By detecting this negative pressure with the tank internal pressure sensor 74 and determining whether or not a predetermined negative pressure has been reached, an abnormality such as perforation of the fuel tank 14 (more broadly, the entire fuel tank system) is detected. It is possible to do.

  In the fuel tank system 12 of the present embodiment, the canister pipe opening / closing valve 58 is closed in a normal state (a state excluding before and after refueling described later). Therefore, the gas (including the evaporated fuel) in the fuel tank 14 does not move to the canister 40.

  Next, the operation of the fuel tank system 12 of this embodiment will be described.

  When the fuel tank 14 is refueled, the vehicle ignition switch is turned off by an occupant (may be a refueler). In this state, when the fuel lid 50 is opened by the operation of the fuel lid opener (pre-fueling pretreatment), the ECU 76 opens the canister pipe opening / closing valve 58. Thereby, the gas in the fuel tank 14 can move to the canister 40.

  When the fuel lid 50 is opened and the fuel cap 42 is also removed, the fuel gun can be inserted into the inlet pipe 32 to supply fuel to the fuel tank 14.

  During refueling, the gas in the fuel tank 14 moves to the canister 40, whereby the gas is replaced with fuel in the fuel tank 14. Thereby, the gas component (gas molecular weight) in the fuel tank 14 decreases. In the canister 40, the evaporated fuel in the gas is adsorbed by the adsorbent and purified. The purified gas is discharged from the atmosphere open pipe 60 to the atmosphere.

  When the fuel level in the fuel tank 14 rises and reaches the valve 38, the gas in the fuel tank 14 is not discharged to the canister 40, so the fuel rises in the inlet pipe 32. When the fuel in the inlet pipe 32 reaches the fueling gun, the fueling gun auto-stop mechanism works to stop the fueling.

  When refueling is completed, the fuel cap 42 is attached to the inlet pipe 32, and the fuel lid 50 is closed. When the ECU 76 closes the canister pipe opening / closing valve 58, the gas discharge path (canister pipe 56) from the fuel tank 14 to the canister 40 is shut off, and the gas does not move from the fuel tank 14 to the canister 40.

  During traveling of the vehicle, as shown in FIG. 1, the canister pipe opening / closing valve 58 is closed. Here, FIGS. 3A to 3E show changes in the tank internal pressure and the tank internal temperature during vehicle travel. In FIGS. 3A to 3E, the atmospheric pressure is P0.

  As shown in FIG. 3A, immediately after refueling, the tank internal pressure is atmospheric pressure P0. The tank internal temperature is T0. This temperature T0 is, for example, the same level as the outside air (however, it is not necessary to match).

  As the vehicle travels, heat acts on the fuel tank 14 to increase the temperature in the tank. FIG. 3B shows an example in which the tank internal temperature rises to T1 and the tank internal pressure rises to P1. The fuel tank 14 may be cooled and the tank internal pressure may decrease.

  When the engine is driven while the vehicle is running, a negative pressure from an intake manifold (not shown) acts in the fuel tank 14. That is, the tank internal pressure of the fuel tank 14 is reduced to a state lower than the atmospheric pressure (negative pressure state).

  Here, for example, in a hybrid vehicle or the like, when the engine drive time is short, the time during which the negative pressure of the intake manifold acts on the fuel tank 14 is also short. Therefore, the decrease in the tank internal pressure of the fuel tank 14 may be small per one engine drive. However, in this embodiment, when engine driving is repeated, the tank internal pressure of the fuel tank gradually decreases accordingly. Further, even when the fuel in the fuel tank 14 is consumed by driving the engine, the gas phase space in the tank increases, so that the gas in the fuel tank 14 expands and the tank internal pressure decreases.

  In this case, even if the tank internal temperature of the fuel tank 14 does not decrease, the tank internal pressure decreases. FIG. 3C illustrates a state in which the tank internal temperature is T1 as in the state illustrated in FIG. 3B and the tank internal pressure has decreased to P2. The tank internal pressure P2 is the same as the negative pressure generated in the intake manifold. In this example, the tank internal pressure P2 is a predetermined value set in advance. On the other hand, when the tank internal temperature of the fuel tank 14 further decreases, the tank internal pressure may further decrease. For example, as shown in FIG. 3D, when the tank internal temperature decreases to T2, the tank internal pressure may decrease by ΔP, which may be lower than the negative pressure of the intake manifold. As for the temperature in the tank, T0 and T2 are both lower than T1, but the levels of T0 and T2 are not particularly limited. That is, the relationship of T2 ≦ T0 <T1 may be used, or the relationship of T0 ≦ T2 <T1 may be used.

  In this way, when the tank internal pressure is in the state of the specified value P2 or lower than P2, the ECU 76 opens the canister pipe opening / closing valve 58 as shown in FIG. The negative pressure in the fuel tank 14 acts on the canister 40 in a short time. Thereby, the evaporated fuel adsorbed by the adsorbent of the canister 40 is desorbed, and the canister 40 is purged. Then, the desorbed evaporated fuel moves into the fuel tank 14. In the example of FIG. 3 (E), the tank internal pressure rises to the atmospheric pressure P0.

  In the fuel tank 14, the evaporated fuel moved from the canister 40 may exist as a gas, but may be liquefied depending on the tank internal temperature or the tank internal pressure of the fuel tank 14. Furthermore, when this gas expands in the fuel tank 14, the temperature in the tank may be lowered and liquefied. And the tank internal pressure of the fuel tank 14 may fall further by the volume decreasing by liquefaction of evaporative fuel. However, as the evaporated fuel moves from the canister 40, the tank internal pressure gradually increases.

  Then, when the tank internal pressure rises to a predetermined value (may be the above-mentioned prescribed value P2 or a tank internal pressure different from this), the ECU 76 closes the canister pipe opening / closing valve 58. As a result, the evaporated fuel is not desorbed in the canister 40.

  As can be seen from the above description, in the fuel tank system 12 of the present embodiment, the negative pressure generated in the engine (intake manifold) is temporarily stored in the fuel tank 14. In other words, the negative pressure generated in the intake manifold is amplified in the fuel tank 14. Then, in a state where the tank internal pressure has reached a specified value (predetermined negative pressure), this negative pressure is applied to the canister 40, whereby the evaporated fuel is desorbed from the adsorbent of the canister 40.

  Here, as a comparative example, a configuration in which the negative pressure of the engine (intake manifold) is directly guided to the canister 40 is considered. In the configuration of the comparative example, for example, when the driving time of the engine is short in a hybrid vehicle or the like, or when the fluctuation of the negative pressure value is large, it may be difficult to sufficiently purge the canister. However, in the fuel tank system 12 of this embodiment, the canister 40 can be reliably purged.

  Moreover, in this embodiment, since the negative pressure of the engine is not used when the canister 40 is purged, even if the engine is stopped or a positive pressure is generated in the engine (intake manifold), The canister 40 can be purged by introducing a negative pressure.

  4 to 6 show a fuel tank system 112 according to a second embodiment of the present invention. In the second embodiment, the same components and members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the fuel tank 114 of the second embodiment, a bellows-like tank expansion / contraction part 20 is configured between the tank upper layer part 16 and the tank lower layer part 18. The tank expansion / contraction part 20 is continuous with the tank upper layer part 16 and the tank lower layer part 18, and can be expanded and contracted in the vertical direction, that is, in the direction in which the tank upper layer part 16 and the tank lower layer part 18 approach or separate. The tank expansion / contraction part 20 expands and contracts in this way, so that the volume of the fuel tank 114 increases or decreases. In particular, the tank expansion / contraction section 20 of the present embodiment is elastic (easily deformable) when the expansion / contraction device 116 described later is driven in a state where the fuel tank 114 is sealed (a state where no gas enters and leaves the outside). )).

  In 2nd Embodiment, it has the external thread shaft 118 and the guide shaft 120 extended below from the retainer 22 of the tank upper wall 114T of the fuel tank 114. As shown in FIG. Further, the outer cylinder 70G of the fuel pump 70 is provided with a substantially cylindrical female screw cylinder 122 into which the male screw shaft 118 is screwed, and a guide cylinder 124 through which the guide shaft 120 is inserted. The distance between the retainer 22 and the outer cylinder 70 </ b> G can be changed by rotating the male screw shaft 118 by the expansion / contraction motor 126 provided on the retainer 22. Since the outer cylinder 70G is attached to the tank lower wall 14B, the tank expansion / contraction part 20 expands / contracts (the tank upper layer part 16 and the tank lower layer part 18 approach or separate from each other), and the tank volume of the fuel tank 114 changes. Therefore, the expansion / contraction device 116 according to the second embodiment includes at least the male screw shaft 118, the female screw cylinder 122, the expansion / contraction motor 126, and the ECU 76.

  Thus, when the retainer 22 and the outer cylinder 70G approach or separate from each other, the guide shaft 120 is inserted into the guide cylinder 124, so that the guide is guided so as not to cause inadvertent backlash and inclination in this operation.

  Further, in the second embodiment, the moving pipe opening / closing valve 128 is provided in the gas moving pipe 52. The opening and closing of the moving pipe on / off valve 128 is controlled by the ECU 76.

  In the fuel tank system 112 of the second embodiment configured as described above, the operation for generating a negative pressure in the fuel tank 114 is different from that of the fuel tank system 12 of the first embodiment. That is, in the second embodiment, as shown in FIG. 5, the ECU 76 drives (normally rotates) the expansion / contraction motor 126 with the canister pipe opening / closing valve 58 and the moving pipe opening / closing valve 128 closed, and the fuel tank 114. Increase the volume of the. As a result, the tank internal pressure of the fuel tank 114 decreases.

  Thereafter, as in the first embodiment, when the tank internal pressure is lower than the specified value P2, the ECU 76 opens the canister pipe opening / closing valve 58 as shown in FIG. The negative pressure in the fuel tank 114 acts on the canister 40 in a short time, and the evaporated fuel adsorbed by the adsorbent of the canister 40 is desorbed (the canister 40 is purged). The desorbed evaporated fuel moves into the fuel tank 114.

  Since the evaporated fuel moves from the canister 40, the tank internal pressure gradually increases. When the tank internal pressure rises to a predetermined value, the ECU 76 closes the canister pipe opening / closing valve 58 and the evaporated fuel is not desorbed in the canister 40.

  Further, in the second embodiment, by reducing the volume of the fuel tank 114, it is possible to send (push out) the gas containing the evaporated fuel in the fuel tank 114 to the engine. That is, the ECU 76 closes the canister pipe opening / closing valve 58 and drives (reversely rotates) the expansion / contraction motor 126 with the moving pipe opening / closing valve 128 closed, thereby reducing the volume of the fuel tank 114 (see FIG. 4). It will be almost the same state). Since the canister pipe opening / closing valve 58 is closed, the gas in the fuel tank 114 does not move to the canister 40, but since the moving pipe opening / closing valve 128 is opened, the gas in the fuel tank 114 is moved to the gas moving pipe 52. Through the engine.

  Thereafter, the ECU 76 can close the canister pipe opening / closing valve 58 and the moving pipe opening / closing valve 128 and drive (normally rotate) the expansion / contraction motor to increase the volume of the fuel tank 114.

  Except for the operation described above, the second embodiment can perform the same operation as the first embodiment. Of course, refueling to the fuel tank 114 is also possible. The canister pipe opening / closing valve 58 is opened and the moving pipe opening / closing valve 128 is closed.

  In the second embodiment, the expansion / contraction means is not limited to the structure in which the fuel tank 114 itself is expanded / contracted by the expansion / contraction device 116 described above, and it is only required that the substantial volume of the fuel tank 114 can be expanded / contracted. For example, as the fuel tank, a fuel tank 14 having a configuration that does not have the tank expansion / contraction portion 20 as in the first embodiment, and a cylindrical cylinder chamber that communicates with the fuel tank 14 outside the fuel tank 14; The structure which provided the piston which moves a cylinder chamber and changes volume may be sufficient. In this configuration, the volume of the region communicating with the fuel tank 14 in the cylinder chamber can be changed by driving the piston by the ECU 76 to change the position.

  In the second embodiment, similarly to the first embodiment, the negative pressure of the engine (intake manifold) may be introduced into the fuel tank 114 through the gas moving pipe 52. However, in the second embodiment, when it is not necessary to introduce the negative pressure of the engine (intake manifold) to the fuel tank 114 and further, it is not necessary to push the gas of the fuel tank 114 to the engine, the gas moving pipe 52 is provided. It may be omitted to simplify the structure, reduce the weight, and reduce the cost.

  In the first embodiment and the second embodiment, in the above description, a configuration in which the tank internal pressure detected by the tank internal pressure sensor 74 is used as a condition for causing the negative pressure in the fuel tanks 14 and 114 to act on the canister 40 is described. However, a configuration in which the negative pressure in the fuel tanks 14 and 114 is applied to the canister 40 under a predetermined condition without directly detecting the tank internal pressure is also possible. For example, in the first embodiment, the engine driving time is added, and when this added value reaches a predetermined value, it is considered that sufficient negative pressure is generated in the fuel tank 14 and the canister pipe opening / closing valve 58 is opened. The canister 40 can be purged. In the second embodiment, if a predetermined amount is set in advance as the drive amount (drive time) of the expansion / contraction motor, and the expansion / contraction motor is driven at a predetermined amount or more, sufficient negative pressure is generated in the fuel tank 114. It can be considered that the canister pipe opening / closing valve 58 is opened and the canister 40 is purged.

  In both the first embodiment and the second embodiment, the canister piping 56 for introducing the negative pressure of the fuel tanks 14 and 114 into the canister 40 is used for introducing the negative pressure of the engine (intake manifold) into the canister 40. Compared to piping, the piping length is short. Since there is little resistance to gas movement, the loss of negative pressure is reduced, and negative pressure can be efficiently introduced into the canister 40.

  Further, the canister pipe opening / closing valve 58 is sufficient if the canister pipe 56 can be opened and closed, and it is not necessary to perform complicated opening adjustment and the like, and can be configured at low cost.

DESCRIPTION OF SYMBOLS 12 Fuel tank system 14 Fuel tank 40 Canister 52 Gas moving piping 56 Canister piping 58 Canister piping on-off valve 60 Atmospheric release pipe 74 Tank internal pressure sensor 112 Fuel tank system 114 Fuel tank 116 Expansion / contraction device 128 Moving piping on-off valve

Claims (4)

A fuel tank containing fuel;
A canister capable of adsorbing evaporated fuel generated in the fuel tank by an adsorbent;
A gas moving pipe for communicating the gas layer in the upper part in the fuel tank and the engine to move the gas in the gas layer to the engine by negative pressure from the engine;
A canister pipe that allows the gas layer and the canister to move between the gas layer and the canister in the upper part of the fuel tank;
A canister pipe opening / closing valve for opening and closing the canister pipe;
Having fuel tank system. A fuel tank containing fuel;
Expansion / contraction means for expanding / contracting the volume of the fuel tank;
A canister capable of adsorbing evaporated fuel generated in the fuel tank by an adsorbent;
A canister pipe that allows the gas layer and the canister to move between the gas layer and the canister in the upper part of the fuel tank;
A canister pipe opening / closing valve for opening and closing the canister pipe;
Having fuel tank system. A gas moving pipe for communicating the gas layer in the upper part in the fuel tank and the engine to move the gas in the gas layer to the engine by negative pressure from the engine;
A moving pipe on-off valve for opening and closing the gas moving pipe;
The fuel tank system according to claim 2. A tank internal pressure sensor for detecting the tank internal pressure of the fuel tank;
Have
The fuel tank system according to any one of claims 1 to 3, wherein the canister pipe opening / closing valve is opened when the tank internal pressure detected by the tank internal pressure sensor is equal to or less than a preset specified value.

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