Evaporative fuel treatment device

Abstract

To provide an evaporative fuel treatment device which can shorten a standby time up until the pressure reduction of a fuel tank is completed at the time of oil supply.SOLUTION: When a fuel remaining quantity in a fuel tank reaches a prescribed fuel remaining quantity threshold or smaller (YES in step S11), a control part controls a sealing valve so as to be opened (step S15). It is preferable that the fuel remaining quantity threshold is set as a fuel remaining quantity at which a fuel remaining quantity alarm light is lit. When it is determined that oil supply to the fuel tank is performed, the control part learns a fuel remaining quantity immediately before the oil supply as the fuel remaining quantity threshold. When it is determined that the oil resupply to the fuel tank is performed after the fuel remaining quantity threshold has been already learned, the control part learns an average value of the learned fuel remaining quantity threshold and the fuel remaining quantity immediately before the oil supply performed again as a new fuel remaining quantity threshold. When it is determined that the fuel remaining quantity in the fuel tank is increased, the control part determines that the oil supply to the fuel tank is performed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an evaporated fuel treatment device. [Background technology]

[0002] Patent Document 1 describes an evaporated fuel control system that includes a differential pressure valve that is disposed on a path connecting a fuel tank body and a canister and opens when the pressure in a diaphragm chamber falls below the pressure of the fuel tank body, a control valve that switches the communication destination so that the diaphragm chamber of the differential pressure valve communicates with either the fuel tank body or a pressure chamber with a predetermined pressure or lower, a detection means that detects the opening and closing of a fuel filler port to the fuel tank, and a control device that controls the control valve to communicate the diaphragm chamber with the pressure chamber only when the detection means detects that the fuel filler port is open. In order to prevent evaporated fuel from being released into the atmosphere from the fuel filler port during refueling, this evaporated fuel control system detects the opening and closing of the fuel filler port using a switch attached to the fuel lid, and when the fuel filler port is open, the control valve opens the differential pressure valve by communicating the diaphragm chamber of the differential pressure valve with a pressure chamber with a predetermined pressure or lower, and guides evaporated fuel in the fuel tank to the canister, thereby reducing the pressure in the fuel tank to atmospheric pressure or lower. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-165003 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the system described in Patent Document 1 directs the evaporated fuel in the fuel tank to the canister on the condition that the open state of the fuel lid is detected, so the system may not be able to complete the decompression of the fuel tank in the short time between when the fuel lid is opened and when the fuel cap is opened. Therefore, with the system described in Patent Document 1, the fuel tank's fuel filler port (fuel cap) cannot be opened until the evaporated fuel in the fuel tank is directed to the canister after the open state of the fuel lid is detected and the pressure in the fuel tank is reduced to below atmospheric pressure, resulting in a problem of a waiting time required until the decompression is completed.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an evaporated fuel treatment device that can reduce the waiting time until the decompression of the fuel tank is completed when refueling. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides an evaporative fuel treatment device having a canister that communicates with a fuel tank via an evaporative fuel introduction passage and adsorbs evaporative fuel generated in the fuel tank, a shut-off valve that is provided in the evaporative fuel introduction passage and closes to prevent evaporative fuel from flowing out of the fuel tank to the canister when an internal combustion engine is stopped, and a control unit that controls the shut-off valve, wherein the control unit controls the shut-off valve to open when the amount of fuel remaining in the fuel tank falls below a predetermined fuel remaining threshold. Effect of the Invention

[0007] According to the present invention, it is possible to provide an evaporated fuel treatment device that can reduce the waiting time until the decompression of the fuel tank is completed when refueling. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle equipped with an evaporated fuel treatment device according to an embodiment of the present invention. [Diagram 2]FIG. 2 is a flow chart illustrating the remaining fuel amount threshold learning operation of the evaporated fuel treatment apparatus according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a flow chart for explaining the shutoff valve control operation of the evaporated fuel treatment apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An evaporative fuel treatment device according to one embodiment of the present invention includes a canister that communicates with a fuel tank via an evaporative fuel introduction passage and absorbs evaporative fuel generated in the fuel tank, a shutoff valve that is provided in the evaporative fuel introduction passage and closes to prevent evaporative fuel from flowing out from the fuel tank to the canister while the internal combustion engine is stopped, and a control unit that controls the shutoff valve, wherein the control unit controls the shutoff valve to open when the amount of fuel remaining in the fuel tank falls below a predetermined fuel remaining amount threshold value, thereby making it possible to reduce the waiting time until the decompression of the fuel tank is completed when refueling. EXAMPLES

[0010] An evaporated fuel treatment device according to an embodiment of the present invention will now be described with reference to the drawings, in which: Figures 1 to 3 are diagrams illustrating an evaporated fuel treatment device according to an embodiment of the present invention.

[0011] As shown in FIG. 1, a vehicle 30 includes an internal combustion engine 20, a fuel tank 6, an evaporated fuel processing device 21, and a control unit 1 that controls the vehicle 30 in an overall manner.

[0012] The internal combustion engine 20 is provided with a plurality of cylinders. The internal combustion engine 20 is configured to perform a series of four strokes, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, for each cylinder. The internal combustion engine 20 is provided with an intake port communicating with a combustion chamber 14 of each cylinder, and an intake pipe 13 that introduces air into the intake port. The intake pipe 13 forms a manifold (intake manifold) at the end on the intake port side that branches toward each intake port, and introduces air into each intake port.

[0013] The internal combustion engine 20 is provided with exhaust ports communicating with the combustion chambers 14 of the cylinders, and an exhaust pipe 15 that discharges exhaust gas from the exhaust ports. The exhaust pipe 15 forms a manifold (exhaust manifold) at the end on the exhaust port side that branches out toward each exhaust port, and is configured to discharge air from each exhaust port.

[0014] A throttle valve 7 and an intake pressure sensor 8 are provided in the intake pipe 13. The throttle valve 7 adjusts the opening of the throttle valve 7 to adjust the air taken in by the internal combustion engine 20. The throttle valve 7 is an electronically controlled throttle valve that is opened and closed by a motor (not shown). The intake pressure sensor 8 detects the pressure downstream of the throttle valve 7 in the intake pipe 13 as the intake pipe pressure and transmits the detected intake pipe pressure to the control unit 1.

[0015] Each cylinder of the internal combustion engine 20 is provided with a fuel injector 9 that injects fuel into the combustion chamber 14 through an intake port, and a spark plug (not shown) that ignites the air-fuel mixture in the combustion chamber 14. The fuel injector 9 and the spark plug are electrically connected to the control unit 1.

[0016] The control unit 1 controls the fuel injection amount and fuel injection timing of the fuel injector 9, and the ignition timing and discharge amount of the ignition plug.

[0017] An exhaust purification device 11 is provided in the exhaust pipe 15. The exhaust purification device 11 has a three-way catalyst (not shown) and purifies the exhaust gas by the action of the three-way catalyst.

[0018] The internal combustion engine 20 is provided with a crank angle sensor 16 , which detects the engine speed based on the rotational position of a crankshaft 17 and transmits a detection signal to the control unit 1 .

[0019] The fuel tank 6 is fixed to a body (not shown) of the vehicle 30, and stores gasoline as fuel for the internal combustion engine 20. The fuel tank 6 is provided with a fuel filler port (not shown), a fuel cap that closes the fuel filler port, and a fuel lid that covers the fuel cap.

[0020] The vehicle 30 includes a fuel pipe 19 that transports fuel from the fuel tank 6 to the fuel injectors 9 of each cylinder, and an electric fuel pump 18 that pressure-feeds fuel from the fuel tank 6 through the fuel pipe 19 to the fuel injectors 9. The fuel pump 18 is controlled by the control unit 1.

[0021] The evaporated fuel processing device 21 discharges evaporated fuel generated in the fuel tank 6 to the intake pipe 13. The evaporated fuel processing device 21 has an evaporated fuel passage 22, a canister 3, a shutoff valve 5, and a purge control valve 2.

[0022] The evaporated fuel passage 22 is connected to the space above the fuel tank 6 and a portion of the intake pipe 13 downstream of the throttle valve 7, and discharges evaporated fuel gas generated in the fuel tank 6 to the portion of the intake pipe 13 downstream of the throttle valve 7.

[0023] The canister 3 is provided in the middle of the evaporated fuel passage 22, and contains an adsorbent such as activated carbon inside. The canister 3 temporarily collects the evaporated fuel generated in the fuel tank 6. This makes it possible to prevent the evaporated fuel from being discharged to the outside of the vehicle 30.

[0024] The evaporated fuel passage 22 has an evaporated fuel introduction passage 23 that communicates with the fuel tank 6 and the canister 3, and an evaporated fuel discharge passage 24 that communicates with the canister 3 and the intake pipe 13. The evaporated fuel introduction passage 23 introduces evaporated fuel generated in the fuel tank 6 to the canister 3. The evaporated fuel discharge passage 24 discharges evaporated fuel adsorbed in the canister 3 to the intake pipe 13. In this way, the canister 3 communicates with the fuel tank 6 via the evaporated fuel introduction passage 23, and adsorbs evaporated fuel generated in the fuel tank 6.

[0025] The shut-off valve 5 is provided in the evaporated fuel introduction passage 23, and closes to prevent evaporated fuel from flowing out from the fuel tank 6 to the canister 3 while the internal combustion engine 20 is stopped. The shut-off valve 5 is controlled by the control unit 1. As the purge control valve 2, for example, a VSV (Vacuum Switching Valve) that is controlled by changing the duty ratio of a drive signal can be used.

[0026] The purge control valve 2 is provided in an evaporated fuel discharge passage 24. The purge control valve 2 adjusts the amount of evaporated fuel gas adsorbed in the canister 3 that is discharged to the intake pipe 13. The purge control valve 2 is controlled by the control unit 1. As the purge control valve 2, for example, a VSV (Vacuum Switching Valve) that is controlled by changing the duty ratio of a drive signal can be used.

[0027] The canister 3 has an atmospheric air inlet 25, and the atmospheric air inlet 25 takes in air into the canister 3 when evaporated fuel is discharged from the canister 3 to the intake pipe 13. Therefore, when evaporated fuel is discharged from the canister 3 to the intake pipe 13, the evaporated fuel in the canister 3 is replaced by the air taken in from the atmospheric air inlet 25.

[0028] The control unit 1 is composed of a computer unit equipped with a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0029] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the control unit 1. That is, the CPU executes the program stored in the ROM using the RAM as a working area, causing these computer units to function as the control unit 1 in this embodiment.

[0030] To an input port of the control unit 1, various sensors including a crank angle sensor 16, an intake pressure sensor 8, and an ignition switch 27 are connected.

[0031] Various control objects including a throttle valve 7, a fuel injector 9, a purge control valve 2, a shutoff valve 5, a fuel pump 18, a fuel level warning light 26, and an ignition plug are connected to an output port of the control unit 1. The control unit 1 controls the various control objects including an internal combustion engine 20 based on information obtained from various sensors.

[0032] The control unit 1 controls the opening and closing of the purge control valve 2 and the shutoff valve 5. In addition, the control unit 1 turns on a remaining fuel warning light 26 in the driver's seat when the remaining fuel in the fuel tank 6 decreases to a predetermined remaining fuel level at which a warning should be issued to the driver.

[0033] Here, in order to prevent the evaporated fuel in the fuel tank 6 from being released into the atmosphere from the fuel filler port when the fuel tank 6 is filled, it is desirable to open the shutoff valve 5 in advance to guide the evaporated fuel in the fuel tank 6 to the canister 3 and complete the depressurization of the fuel tank 6 before the fuel lid of the fuel tank 6 is opened for refueling. In this way, it is possible to prevent the evaporated fuel from being released into the atmosphere when filling the fuel tank 6, and to reduce the waiting time until the depressurization of the fuel tank 6 is completed.

[0034] One method for reducing the waiting time until the pressure reduction of the fuel tank 6 is completed during refueling is to frequently open the shutoff valve 5 so that the internal pressure of the fuel tank 6 is always maintained close to atmospheric pressure, and to send evaporated fuel to the canister 3 frequently. However, in this case, it is necessary to perform purge control (opening of the purge control valve 2) frequently in consideration of the adsorption capacity of the canister 3, and therefore, there are more opportunities to start the internal combustion engine 20 for the sole purpose of purge control during EV driving or idling stop, which causes a deterioration in fuel efficiency.

[0035] Therefore, rather than opening the shutoff valve 5 so as to constantly maintain the internal pressure of the fuel tank 6 at a value close to atmospheric pressure, it is desirable to open the shutoff valve 5 in a situation (timing) where there is a high possibility that refueling will occur in the fuel tank 6. A situation where there is a high possibility that refueling will occur in the fuel tank 6 is a situation where the amount of fuel remaining in the fuel tank 6 has decreased to the extent that refueling is necessary.

[0036] Therefore, the control unit 1 controls the shutoff valve 5 to open when the remaining fuel in the fuel tank 6 falls below a predetermined fuel remaining threshold. This fuel remaining threshold is a fuel remaining amount so small that refueling is necessary. The fuel remaining threshold is preferably a fuel remaining amount at which the fuel remaining warning light 26 is turned on. The situation in which the fuel remaining warning light 26 is turned on is a situation in which the possibility of refueling the fuel tank 6 being refueled is extremely high.

[0037] When the control unit 1 determines that the fuel tank 6 has been refueled, it learns the remaining fuel amount immediately before refueling as the remaining fuel amount threshold. That is, the control unit 1 uses the remaining fuel amount at which the remaining fuel warning light 26 is turned on as the initial value of the remaining fuel amount threshold, and when the fuel tank 6 has been refueled, it learns the remaining fuel amount at that time as the remaining fuel amount threshold, and updates the remaining fuel amount threshold to the learned value. This is because the timing of refueling the fuel tank 6 (remaining fuel amount) differs for each driver, and it is necessary to learn the timing of past refueling and accurately predict the next timing of refueling.

[0038] When the control unit 1 determines that the fuel tank 6 has been refueled again after the remaining fuel amount threshold has already been learned, the control unit 1 learns the average value of the learned remaining fuel amount threshold and the remaining fuel amount immediately before the re-refueling as a new remaining fuel amount threshold. In other words, the control unit 1 calculates a new remaining fuel amount threshold and updates it to the new remaining fuel amount threshold every time the fuel tank 6 is refueled.

[0039] The control unit 1 determines that the fuel tank 6 has been refueled if the amount of fuel remaining in the fuel tank 6 has increased. This is because if the presence or absence of refueling were determined based on the opening and closing of the fuel lid of the fuel tank 6, it would be impossible to determine whether or not refueling has actually occurred, whereas if the amount of fuel remaining in the fuel tank 6 has increased, it is possible to determine that the fuel tank 6 has been refueled.

[0040] Next, a remaining fuel amount threshold learning operation executed by the control unit 1 in the evaporated fuel processing device 21 according to this embodiment will be described with reference to Fig. 2. This operation is repeatedly executed at predetermined intervals.

[0041] First, the control unit 1 detects the amount of fuel remaining in the fuel tank 6 (step S1).

[0042] Next, the control unit 1 determines whether or not the remaining fuel amount has increased (step S2). That is, the control unit 1 determines whether or not fuel has been refueled into the fuel tank 6.

[0043] If the remaining amount of fuel has not increased (NO in step S2), the control unit 1 returns to step S1 and continues detecting the remaining amount of fuel.

[0044] If the remaining fuel amount has increased (YES in step S2), the control unit 1 learns the remaining fuel amount immediately before the increase as the remaining fuel amount threshold (step S3), and ends the current operation.

[0045] Here, fuel is refueled to the fuel tank 6 with the ignition switch 27 turned off and the operation of the internal combustion engine 20 stopped. Therefore, the control unit 1 does not need to constantly determine whether the remaining fuel amount has increased in step S2, and can perform the determination by comparing the remaining fuel amount immediately before the ignition switch 27 is turned off with the remaining fuel amount immediately after the ignition switch 27 is turned on after refueling.

[0046] Next, the shutoff valve control operation executed by the control unit 1 in the evaporated fuel treatment device according to this embodiment will be described with reference to Fig. 3. This operation is repeatedly executed at predetermined intervals.

[0047] The control unit 1 detects the amount of fuel remaining in the fuel tank 6 (step S10).

[0048] Next, the control unit 1 determines whether or not the amount of remaining fuel in the fuel tank 6 is equal to or less than a predetermined fuel remaining amount threshold (step S11).

[0049] If the remaining fuel amount is not equal to or less than the remaining fuel amount threshold (NO in step S11), the control unit 1 returns to step S10 and continues comparing the remaining fuel amount with the remaining fuel amount threshold.

[0050] When the remaining fuel amount is equal to or less than the remaining fuel amount threshold (YES in step S11), the control unit 1 estimates the amount of evaporated fuel based on the internal pressure of the fuel tank 6 and the like (step S12). The evaporated fuel amount is the amount of evaporated fuel present in the fuel tank 6.

[0051] Next, the control unit 1 estimates the remaining adsorption amount from the adsorption capacity and current adsorption amount of the canister 3 (step S13). The adsorption capacity is the total amount of evaporated fuel that can be adsorbed by the canister 3. The current adsorption amount is the amount of evaporated fuel currently adsorbed in the canister 3. The remaining adsorption amount is the amount of evaporated fuel remaining that can be adsorbed by the canister 3 when evaporated fuel is adsorbed in the canister 3. In this step S13, the control unit 1 calculates the remaining adsorption amount by subtracting the current adsorption amount from the adsorption capacity.

[0052] Here, the current adsorption amount correlates with the concentration (purge concentration) of the evaporated fuel discharged from the canister 3 to the intake pipe 13. The higher the purge concentration, the larger the current adsorption amount, and the lower the purge concentration, the smaller the current adsorption amount. Therefore, the purge concentration is calculated based on information from an air-fuel ratio sensor (not shown) and the current adsorption amount can be estimated from the calculated purge concentration. In detail, the evaporated fuel in the canister 3 flows into the intake pipe 13, causing the air-fuel ratio (λ) to deviate from the control target air-fuel ratio to the rich side, and therefore air-fuel ratio feedback control is executed. The magnitude of the control amount of this air-fuel ratio feedback control coincides with the magnitude of the discharge amount and concentration of the evaporated fuel discharged from the canister 3 to the intake pipe 13. Therefore, the purge concentration can be calculated based on the control amount of this air-fuel ratio feedback control. In addition, as an example, the purge concentration used to calculate the current adsorption amount can be the purge concentration acquired when the immediately previous purge control was executed. As another example, the purge concentration used in calculating the current adsorption amount can be obtained by performing a short-term trial purge control at the timing when the current adsorption amount should be calculated, and using the purge concentration obtained when this purge control is performed.

[0053] Next, the control unit 1 judges whether or not the remaining adsorbable amount is greater than the amount of evaporated fuel (step S14).

[0054] If the remaining adsorbable amount is greater than the amount of evaporated fuel (YES in step S14), the control unit 1 opens the shutoff valve 5 (step S15) and ends this operation. By opening the shutoff valve 5 in step S15, the evaporated fuel in the fuel tank 6 moves through the evaporated fuel introduction passage 23 to the canister 3, and the pressure in the fuel tank 6 is reduced.

[0055] On the other hand, when the control unit 1 determines that the remaining adsorbable amount is not greater than the amount of evaporated fuel (NO in step S14), it determines whether or not the internal combustion engine 20 is in operation (step S16).

[0056] Next, if the internal combustion engine 20 is operating (YES in step S16), the control unit 1 executes purge control of the canister 3 (step S17) and returns to step S12. Purge control is an operation of opening the purge control valve 2 to discharge evaporated fuel from the canister 3 to the intake pipe 13. The amount of evaporated fuel discharged from the canister 3 to the intake pipe 13 by the purge control is an amount necessary to make the remaining adsorbable amount of the canister 3 greater than the amount of evaporated fuel. By executing the purge control, the remaining adsorbable amount of the canister 3 can be made greater than the amount of evaporated fuel.

[0057] If the internal combustion engine 20 is not in operation (NO in step S16), the control unit 1 starts the internal combustion engine 20 (step S18), executes the purge control of the canister 3 (step S17), and returns to step S12.

[0058] In this way, when the internal combustion engine 20 is not operating because the vehicle 30 is in EV driving or idling stop, the control unit 1 executes purge control after starting the internal combustion engine 20, so that the evaporated fuel can be burned in the internal combustion engine 20 and the evaporated fuel can be prevented from being released into the atmosphere. It is preferable to charge a battery (not shown) during execution of the purge control and accumulate the kinetic energy generated by the internal combustion engine 20 as electrical energy. Also, when execution of the purge control is expected, it is preferable to lower the state of charge (SOC) of the battery in advance so that all the generated power can be charged.

[0059] As described above, in this embodiment, the control unit 1 controls the shutoff valve 5 to open when the amount of remaining fuel in the fuel tank 6 becomes equal to or less than a predetermined fuel remaining amount threshold.

[0060] As a result, when the remaining fuel in the fuel tank 6 falls below the fuel remaining threshold, since there is a high possibility that refueling will be performed in the fuel tank 6, the shut-off valve 5 can be opened to reduce the pressure inside the fuel tank 6 prior to refueling.

[0061] As a result, the waiting time until the decompression of the fuel tank 6 is completed during refueling can be reduced.

[0062] In this embodiment, the fuel remaining amount threshold is the amount of fuel remaining at which the fuel remaining amount warning light 26 is turned on.

[0063] As a result, when the amount of fuel remaining in the fuel tank 6 has decreased to a level at which the remaining fuel warning light 26 is illuminated, there is a high possibility that fuel will be refueled into the fuel tank 6. Therefore, by opening the shut-off valve 5 in advance to reduce the pressure inside the fuel tank 6 before refueling, the waiting time until the pressure reduction in the fuel tank 6 is completed during refueling can be reduced.

[0064] Furthermore, in this embodiment, when the control unit 1 determines that fuel has been refueled into the fuel tank 6, it learns the remaining fuel amount immediately before refueling as the remaining fuel amount threshold value.

[0065] As a result, the remaining fuel amount immediately before refueling is learned as a fuel remaining amount threshold, and the timing of the next refueling of the fuel tank 6 can be accurately estimated from the remaining fuel amount. Therefore, by opening the shut-off valve 5 in advance to reduce the pressure inside the fuel tank 6 when there is a high possibility of refueling, the waiting time until the depressurization of the fuel tank 6 is completed during refueling can be reduced.

[0066] In addition, in this embodiment, if the control unit 1 determines that the fuel tank 6 has been refueled again after the fuel remaining amount threshold has already been learned, it learns the average value of the learned fuel remaining amount threshold and the fuel remaining amount immediately before the re-refueling as a new fuel remaining amount threshold.

[0067] As a result, the fuel remaining amount threshold is updated to a new fuel remaining amount threshold each time the fuel tank 6 is refueled, making it possible to more accurately determine whether or not there is a high possibility of refueling. If it is determined that there is a high possibility of refueling, the shut-off valve 5 is opened in advance to reduce the pressure inside the fuel tank 6, thereby reducing the waiting time until the depressurization of the fuel tank 6 is completed when refueling.

[0068] Furthermore, in this embodiment, the control unit 1 determines that the fuel tank 6 has been refueled when the amount of fuel remaining in the fuel tank 6 has increased.

[0069] As a result, it is determined that the amount of fuel remaining in the fuel tank 6 has increased based on an increase in the amount of remaining fuel, so that the accuracy of learning the fuel remaining threshold can be improved, and by opening the shut-off valve 5 in advance to reduce the pressure inside the fuel tank 6 when it is determined that there is a high possibility of refueling, the waiting time during refueling can be reduced.

[0070] Although an embodiment of the invention has been disclosed, it will be apparent to one of ordinary skill in the art that modifications may be made thereto without departing from the spirit and scope of the invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0071] 1. Control section 3 Canister 5. Shut-off valve 6. Fuel Tank 20 Internal Combustion Engine 23 Fuel vapor introduction passage 26 Fuel level warning light

Claims

1. a canister communicating with the fuel tank through a fuel vapor introduction passage for absorbing fuel vapor generated in the fuel tank; a shutoff valve provided in the evaporated fuel introduction passage and configured to close to prevent evaporated fuel from flowing out from the fuel tank to the canister while the internal combustion engine is stopped; A control unit for controlling the shutoff valve, The control unit controls the shutoff valve to open when the amount of fuel remaining in the fuel tank becomes equal to or less than a predetermined fuel remaining threshold value.

2. 2. The fuel vapor treatment device according to claim 1, wherein the fuel remaining amount threshold value is a fuel remaining amount at which a fuel remaining amount warning light is turned on.

3. 2. The apparatus according to claim 1, wherein the control unit, when determining that the fuel tank has been refueled, learns the remaining fuel amount immediately before the refueling as the remaining fuel amount threshold value.

4. The evaporative fuel treatment device according to claim 3, characterized in that when the control unit determines that the fuel tank has been refueled again after the fuel remaining amount threshold has already been learned, it learns an average value between the learned fuel remaining amount threshold and the fuel remaining amount immediately before the re-refueling as a new fuel remaining amount threshold.

5. 5. The fuel vapor processing device according to claim 3, wherein the control unit determines that the fuel tank has been refueled when the amount of fuel remaining in the fuel tank has increased.

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