Method and system for determining whether a fuel filler door is closed

Abstract

Method implemented by a data processing device for detecting whether a fuel filler cap of a motor vehicle is closed and device for implementing such a method.

Description

Field of the invention

[0001] The field of the invention is a method and a system for determining whether a refuelling filler cap of a motor vehicle is closed. BACKGROUND

[0002] After the refuelling process is completed, the fuel tank cap must be attached in a fluid-tight manner to the refuelling connection in order to prevent fuel vapour from escaping from the fuel tank. It is thus desirable to provide a method or a device which indicates to the user of the motor vehicle in a reliable manner whether the fuel tank cap is attached in a fluid-tight manner to the refuelling connection as soon as possible before the vehicle departs or after the refuelling process has just been completed.

[0003] In view of this, it is an object of the invention to provide a method for ascertaining whether the fuel tank cap is attached in a fluid-tight manner to the refuelling connection. SUMMARY

[0004] The invention relates to a method for detecting whether a refuelling filler cap of a motor vehicle is closed, which is carried out by a data processing device.

[0005] The method comprises the following steps:

[0006] obtaining a value of a first pressure in a gas chamber of a fuel tank of the motor vehicle;

[0007] outputting a signal to open a recirculation line leading from the fuel tank to a refuelling connection of the fuel tank;

[0008] obtaining a value of a second pressure in the gas chamber of the fuel tank;

[0009] if the second pressure is less than the first pressure by a certain preset value, determining that the refuelling filler cap is not closed and outputting a value of a closure state which indicates that the refuelling filler cap is not closed on the refuelling connection.

[0010] The method can be carried out in the order of the steps described above.

[0011] The method is based on the recognition that when the fuel tank is full, the fuel rises in the refuelling line. This means that the liquid level in the refuelling line can be higher than the liquid level in the fuel tank. That is, the liquid level in the refuelling line is in the upper part of the refuelling line or in the refuelling connection above it. At this point in time, an atmosphere exists above this liquid level.

[0012] At this point in time, all gas-conducting (vent) lines connected to the fuel tank are fluidically sealed from the atmosphere. At this point in time, a pressure prevails in the gas chamber of the fuel tank which is higher than the atmospheric pressure. In this case, the fuel filler cap should normally be closed by attaching the fuel tank cap to the filler pipe or another corresponding closure device. If this is not the case, opening the recirculation line according to the method leads to the connection of the following three atmospheres: the atmosphere above the liquid level in the filler pipe, the atmosphere in the gas chamber of the fuel tank and the atmosphere. The other gas-conducting (vent) lines connected to the fuel tank, apart from the recirculation line, are not open at this point in time. By connecting the above-mentioned three atmospheres together, the pressure in the gas chamber of the fuel tank essentially falls to a pressure level corresponding to the pressure in the atmosphere. By being able to determine that the second pressure is less than the first pressure to a certain preset extent, it can be determined that the fuel filler cap is not closed. In the case of a fluidically sealed closure of the fuel filler cap, on the other hand, it will be determined that only a small pressure drop has occurred, i.e. the second pressure is not less than the first pressure to a certain preset extent.

[0013] The advantage of the method is that the closure state of the fuel filler cap can be determined by means of the pressure in the gas chamber. This makes it unnecessary to use any sensors or contact sensors or other mechanical devices on the fuel tank cap. Such devices on the tank cap can wear out due to the constant mechanical load when opening and closing the fuel tank cap, or cause false determinations / messages due to dirt being brought between the fuel tank cap and the filler neck.

[0014] The recirculation line means any line or vent line leading from the fuel tank to the filler neck of the fuel tank, such as a filler vent line.

[0015] The gas chamber of the fuel tank means a region of the fuel tank which, in the installed position, is not filled with fuel to a preset maximum even after the fuel tank has been refueled, so that only gaseous fluid (at the usual operating temperatures of the fuel tank or motor vehicle) is present in this gas chamber.

[0016] The time period between the determination of the first and second pressure can be less than 10 seconds, 8 seconds, 6 seconds, 4 seconds, 3 seconds, 2 seconds or 1 second.

[0017] The time interval between the determination of the first and second pressure can be preset, for example, it can be 10 seconds, 8 seconds, 6 seconds, 4 seconds, 3 seconds, 2 seconds or 1 second. Alternatively or additionally, the value relating to the determination of the second pressure can be determined by the data processing device in the case where a change in the value of the second pressure does not occur after 1, 2, 3, 4 or 5 seconds.

[0018] The pressure can be determined by means of a pressure sensor. The pressure sensor can transmit the determined (measured) pressure values to a processing unit, for example a data processing device, by means of a signal line. The data of the values can be transmitted by means of a signal line, analogously or digitally. In principle, all signals can be transmitted between the components of the system described herein, digitally or analogously. All common signal lines are suitable for this, for example cables, cable systems, bus systems, signal lines with electrical or optical transmission or wireless signal paths, such as Bluetooth, WiFi, RFID, radio or infrared transmission. The pressure sensor necessarily has a (fluidic) passage to the gas chamber, but the position of the pressure sensor or the position of the passage of the pressure sensor to the gas chamber in the fuel tank system is not limited in the case of a passage to the gas chamber. The passage of the pressure sensor can be in the recirculation line, for example, at a position which enables a passage to the gas chamber even after the recirculation line is closed. The position of the passage can also be in the tank cap or in the fuel tank side wall.

[0019] In the case of digital transmission of the values, the sensor is equipped with or coupled with a digital-to-analog converter to generate a digital signal.

[0020] The pressure to be measured can be an absolute pressure, i.e. a pressure which is not given with reference to a pressure in another fluid. That is to say, the pressure sensor can measure the absolute pressure in the gas chamber. Alternatively, the pressure can be a differential pressure. The differential pressure can be measured with a differential pressure sensor. The differential pressure sensor can have a passage to the gas chamber and to the atmosphere in order to determine the pressure difference to the atmosphere in this way. Alternatively, the differential pressure can also be measured by means of two pressure sensors which each determine the absolute pressure in the gas chamber or the absolute pressure in the atmosphere, wherein the pressure difference is determined on the basis of the measured values of the two pressure sensors in the data processing device or another device for outputting the differential pressure.

[0021] The signal for opening the recirculation line can be transmitted by means of a signal line. The recirculation line can be opened and closed by means of any known means for closing and opening a line for conveying a gaseous fluid, i.e. a shut-off mechanism. This includes a valve, a gate valve or a shut-off valve. The shut-off mechanism can be controlled by means of a signal line by the data processing device. The shut-off mechanism is an (electrically) motorically or (electrically) magnetically actuated shut-off mechanism or a shut-off mechanism with a Shape Memory Alloy Aktuator. In the case of the use of an optical signal line, the shut-off mechanism is equipped with a power supply. The shut-off mechanism in the recirculation line can be referred to as a recirculation shut-off mechanism or a recirculation shut-off valve.

[0022] The method can comprise the step of transmitting a signal to interrupt the connection of the gas chamber to the atmosphere before the above-mentioned steps. From the gas chamber of the fuel tank there can be a plurality of lines which are in direct or indirect contact with the atmosphere, for example recirculation lines or lines which are part of filter systems or / and (other) exhaust systems, such as activated carbon filter systems, which are known, for example, by the ORVR system (On-Board Refueling Vapor Recovery System) or the EVR system (External Vapor Recovery System). By interrupting the connection of the gas chamber to the atmosphere, the first pressure in the gas chamber can be greater than the pressure in the atmosphere. This leads to the consequence (while refueling is continued) that the level in the refueling line rises above the level in the fuel tank. In addition, the rising level in the refueling line also leads to the interruption of the refueling operation due to the closure of the dispenser valve of the fueling station. Further refueling can also be possible by manual activation of the opening of the dispenser valve.

[0023] Alternatively, the connection of the gas chamber to the atmosphere can also be interrupted by a mechanical or construction-related design of the (refueling exhaust) valve in the (refueling exhaust) line. For example, the (refueling exhaust) valve can be closed when a certain predetermined level in the fuel tank occurs, without a signal having to be sent by the data processing device.

[0024] The transmission of the signal to interrupt the connection of the gas chamber to the atmosphere can comprise the transmission of a signal to interrupt the recirculation line.

[0025] The method can be executed after determining that

[0026] i) the fuel tank has been filled to capacity,

[0027] ii) the tank flap on the fuel filler cap has been closed,

[0028] iii) the engine for the vehicle to travel has been started, or

[0029] iv) the refueling process has been defined as complete by the data processing device.

[0030] Or two, three or four of these conditions i) to iv) are present.

[0031] The method is implemented after it has been determined that the fuel tank has been filled. This has the advantage that the method is applied at a point in time at which the filler cap has presumably not been closed correctly. In order to determine whether the fuel tank has been filled, it can be determined that the level in the fuel tank has risen since a previous point in time and has not risen again within a defined time window. In order to measure the level in the fuel tank, a float device, a capacitive measuring device or a proximity sensor, for example an ultrasonic sensor, can be used as a sensor. The sensor for measuring the level can transmit data about the level to a data processing device via a signal line, in which data processing device data about the previous level can also be stored. By comparing the current level data with the previous level data, it can be determined whether the fuel tank has been filled.

[0032] The method can also comprise determining that the fuel tank has been filled, wherein it is determined that the fuel tank has been filled to its maximum capacity. The maximum capacity can be determined when the reservoir has been filled to a defined level.

[0033] The method can also comprise determining that the fuel tank has been filled, wherein the fuel level in the fuel tank filler pipe is higher than the level in the fuel tank. This indicates that the pressure in the gas chamber of the fuel tank is higher than atmospheric pressure. The fuel tank filler pipe extends from the fuel tank to the filler neck.

[0034] The method is implemented after it has been determined that the fuel tank flap on the fuel filler cap has been closed. This has the advantage that the method is initiated at a point in time at which the filler cap has presumably not been closed correctly.

[0035] The fuel tank flap serves to cover the fuel tank cap and, for example, has the function of visually covering the fuel tank cap and, when closed, of forming a unitary appearance with the surface of the vehicle body. In addition, the fuel tank flap can have the function of locking access to the passage to the fuel filler cap.

[0036] In order to determine whether the fuel tank flap on the fuel filler cap is closed, it can be determined that a contact sensor device (magnetic, electrical, visual or acoustic) on the fuel tank flap indicates whether the fuel tank flap has been opened and reclosed. Via a signal line, the contact sensor device can transmit data about the opening and closing of the fuel tank cap to a data processing device, in which data processing device data about previous opening and closing of the fuel tank cap can also be stored.

[0037] The method is implemented after it is determined that the engine for the vehicle to travel has been started. This has the advantage that the method is applied precisely in the case where there is a risk that the vehicle will move, for example after refueling, and the fuel filler cap is not closed. Furthermore, the user still has the opportunity at this point in time to close the fuel filler cap correctly before the vehicle moves. The engine for the vehicle to travel can be an internal combustion engine or an electric motor, for example an electric motor of a hybrid vehicle. It is not important whether the fuel refueled is used to operate the engine for the vehicle to travel, the only important thing is that it is determined that the vehicle will most likely move soon. If several conditions i) to iv) are checked, then step iii) should be checked last. The method should be activated at the latest at this point in time.

[0038] The method is implemented after it is determined that the refueling process is defined as completed by the data processing device. This has the advantage that the method can be implemented immediately after refueling has ended. The data processing device can define the refueling process as completed in the case where the vehicle sensor indicates that the refueling process is complete on the basis of data transmission. Alternatively, the data processing device can define the refueling process as completed in the case where the refueling device, for example a refueling tower, indicates to the data processing device that the refueling process is complete on the basis of direct or indirect data transmission.

[0039] The method can be implemented after the presence of conditions i), ii), iii), iv), optionally in the time sequence i), ii) (and / or iv)), iii).

[0040] The method can be implemented after the presence of conditions i), ii), optionally in the time sequence of conditions i), ii).

[0041] The method can be implemented after the presence of conditions i), iii), optionally in the time sequence i), iii).

[0042] The method can be implemented after the presence of conditions i), iv), optionally in the time sequence i), iv).

[0043] The value of the first pressure can be at least 100 Pascal (1 mbar), at least 200 Pascal (2 mbar), at least 300 Pascal (5 mbar), at least 500 Pascal (5 mbar), at least 1000 Pascal (10 mbar) or at least 2000 Pascal (20 mbar) above the pressure in the atmosphere. The pressure in the atmosphere refers to the pressure present in the atmosphere surrounding the vehicle (for example 1013.25 hPa as standard pressure, which fluctuates depending on the weather and the altitude). With this value of the first pressure, the difference to the second pressure value can be determined very well.

[0044] The second pressure can be at least 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% lower than the first pressure (i.e. the preset value is a value of 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% of the first pressure value). With these pressure differences it is possible to determine very well whether the filler cap is not closed to the filling connection.

[0045] The value of the first pressure and the value of the second pressure can each represent a value of a differential pressure relative to the atmosphere. The value of the atmospheric pressure can be obtained by measuring the atmospheric pressure, calibrating the pressure sensor or by a preset in the data processing device.

[0046] The values of the first pressure and the second pressure can be absolute values in Pascal, and the second pressure can be at least 85 Pascal, 100 Pascal, 150 Pascal, 200 Pascal, 250 Pascal, 300 Pascal, 350 Pascal, 400 Pascal, 450 Pascal, 500 Pascal, 550 Pascal, 600 Pascal, 650 Pascal, 750 Pascal, 800 Pascal, 850 Pascal, 900 Pascal or 1000 Pascal lower than the first pressure. I.e. the preset value indicating that the filler cap is not closed when comparing the first pressure and the second pressure can be 85 Pascal, 100 Pascal, 150 Pascal, 200 Pascal, 250 Pascal, 300 Pascal, 350 Pascal, 400 Pascal, 450 Pascal, 500 Pascal, 550 Pascal, 600 Pascal, 650 Pascal, 750 Pascal, 800 Pascal, 850 Pascal, 900 Pascal or 1000 Pascal. With these pressure differences it is possible to determine very well whether the filler cap is closed to the filling connection.

[0047] During the continuous measurement of the pressure in the fuel tank, the data processing device can also determine the rate at which the pressure change occurs after the recirculation line is opened, i.e. the speed of the pressure change. Continuous measurement means that the data processing device obtains data from the pressure sensor about the pressure in the gas chamber of the fuel tank at least every 1000 ms, 500 ms, 300 ms, 100 ms, 50 ms, 30 ms or 10 ms. When a preset threshold value is exceeded, the closed state can be determined from the speed.

[0048] The output represents a value indicating the closed state of the closure of the filler cap of the filler neck, which can lead to an output signal that can be perceived by the user. The data processing device can transmit the output value to a signal generator in the passenger interior space via a signal line. The signal transmitter can output a visual, audible or haptic output signal in the passenger interior space, which can serve as an alarm signal. The visual output signal can be an activated warning light. The warning light can be part of a dashboard, which comprises an indicator or instrument panel and comprises a digital or analog warning light, which can also be part of an indicator of a head-up display.

[0049] The invention also relates to a method for detecting whether a fuel filler cap of a motor vehicle is closed, comprising the aforementioned method and comprising the following steps:

[0050] - determining a first pressure present in a gas chamber of a fuel tank of the motor vehicle;

[0051] - opening a recirculation line leading from the fuel tank to a filler neck of the fuel tank;

[0052] - determining a second pressure present in the gas chamber of the fuel tank;

[0053] - determining that the fuel filler cap is not closed if the second pressure is less than the first pressure by a certain preset value.

[0054] The invention also relates to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the aforementioned method.

[0055] The invention also relates to a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the aforementioned method.

[0056] The invention also relates to a data processing device comprising means for carrying out the aforementioned method.

[0057] The invention also relates to a system for detecting whether a fuel filler cap of a motor vehicle is closed, comprising

[0058] a fuel tank having a tank filler pipe and a filler neck;

[0059] a recirculation line leading from the fuel tank to the filler neck of the fuel tank;

[0060] a sensor for detecting a pressure in a gas chamber of the fuel tank;

[0061] a closure device on the filler neck for separating the fuel tank from the atmosphere; and

[0062] a data processing device as defined previously.

[0063] The system can comprise means for determining the level in the fuel tank. The system can comprise means for terminating the refueling process of the fuel tank. The system can in particular comprise means for a refueling vent valve of the fuel tank. The refueling vent valve means can comprise a mechanical or electromechanical refueling vent valve arranged in a line which vents gas from a gas chamber of the fuel tank and which is opened during refueling.

[0064] The means for determining the level can transmit a signal to the data processing means that the predetermined or maximum level is reached in the fuel tank. In response to this, the data processing means can transmit a signal to the refueling vent valve means to close the refueling vent valve means.

[0065] Alternatively, the refueling vent valve means can be closed by the construction of the refueling vent valve, such as a float valve whose float causes the closure of the valve seat. The refueling vent valve means can be arranged in and corresponding to the recirculation line or in another line for venting the fuel tank.

[0066] The fuel tank can be made of any suitable material, such as plastic, such as HDPE, or metal. The plastic fuel tank can be made by blow molding or injection molding.

[0067] The fuel tank can comprise all common means or units, such as a fuel pump, a roll-over valve, fuel lines or connections thereof, sensors other than pressure sensors, such as temperature sensors, ultrasonic sensors, a float, a baffle, internal and external support means for stabilizing the fuel tank.

[0068] The fuel tank can in particular be constructed as a system for reducing hydrocarbon emissions during refueling, such as an ORVR system (onboard refueling vapor recovery system) or an EVR system (external vapor recovery system). The fuel tank can thus have a refueling vent valve which can establish a fluid connection from the gas chamber of the fuel tank to an activated carbon filter by means of a line. The activated carbon filter can be connected to a vent valve by means of another line, which vent valve is connected to a discharge line. The activated carbon filter can be connected to a leak detection unit, for example in an ORVR system, by means of another line.

[0069] The wall of the fuel tank can be single- or multi-layered and contain one or more barrier layers, which are made of a material that is impermeable to the hydrocarbons contained in the fuel, such as EVOH.

[0070] The data processing means can be any common means for data processing, such as a processor, which has a working memory and a storage medium connected by a data bus.

[0071] DRAWINGS

[0072] Figure 1 is a schematic view of a fuel tank system. Figure 1 The liquid level in the fuel tank and in the fuel tank filler pipe is indicated at the point in time when the (recirculation line) valve is closed.

[0073] Figure 2 is a schematic view of the fuel tank system in the state at the point in time when the valve is open and the fuel tank cap is not fluidically attached to the filler neck. Figure 1

[0074] Figure 3 is a schematic view of the fuel tank system in the state at the point in time when the valve is open and the fuel tank cap is attached to the filler neck. Figure 1

[0075] Figure 4 shows a fuel tank system as an ORVR system (on-board refueling vapor recovery system).

[0076] Example

[0077] Figure 1 shows a fuel tank system with a fuel tank 2, a fuel tank filler pipe 6 arranged thereon, to which a filler neck 4 is attached. Furthermore, a pressure sensor 5 is arranged on the recirculation line 3, which establishes a fluid connection between the gas space 1 and the volume in the filler neck 4. However, the pressure sensor can be attached at any position of the fuel system in case it leads to the gas space 1. In the recirculation line, a controllable recirculation line valve 9 is arranged, which interrupts the connection between the gas space 1 and the volume in the filler neck 4.

[0078] Furthermore, the fuel tank system comprises a device 7 for data processing. The device 7 can be connected to sensors, controllable valves, output systems, such as signal generators, or other actuators by signal lines, also called data lines or data exchange lines. The fuel tank system can have a data line between the recirculation line valve 9 and the device 7, a data line 11 between the pressure sensor and the device 7, and a data line 12 between the device 7 and the signal generator.

[0079] Figure 1 shows the fuel tank system with no (gas) connection of the gas space 1 to the atmosphere. The recirculation line valve 9 is closed G, so that the connection of the gas space 1 to the filler neck 4 is interrupted.

[0080] ​​The method of the application starts at this point in time, which can be triggered, for example, by the device 7 determining that the fuel tank 2 is filled or completely filled, that the open fuel tank flap (not depicted) is closed, or that the engine (not depicted) is activated (or started) for travel.

[0081] In the gas chamber 1 there is a first pressure which is greater than atmospheric pressure. The level height Y1 in the fuel tank filler pipe 6 is higher than the level height X1 in the fuel tank 2. The gas chamber 1 is above the level in the fuel tank. At this point in time, the fuel filler cap is not closed, i.e. the fuel tank cap is not attached to the filler neck.

[0082] At Figure 1 At the point in time shown, the device 7 for data processing receives from the pressure sensor 5 a value relating to the pressure level in the gas chamber 1, i.e. a value relating to the first pressure.

[0083] The following is described Figure 2 and 3 The next course of the method is shown for the case in which the fuel tank cap 13 is fluid-tightly attached ( Figure 3 ) or not fluid-tightly attached ( Figure 2 ).

[0084] Figure 2 The fuel system is shown in the state in which the fuel tank cap 13 is not fluid-tightly attached.

[0085] Figure 2 In particular, the fuel system is shown after the recirculation line valve 9 has been opened O by a signal from the device 7 via the data line 11. The gas chamber 1 is in gaseous connection via the open recirculation line 3 with the filler neck 4, which leads to the atmosphere. This leads to a drop in the pressure in the gas chamber 1 within a short time. In addition, the liquid in the fuel tank 2 and the liquid in the fuel tank filler pipe are subjected to the same or at least approximately the same pressure. As a result, the level height Y2 in the fuel tank filler pipe 6 matches the level height X2 in the fuel tank 2 until it reaches the same or almost the same level.

[0086] At Figure 2 At the point in time shown, the device 7 for data processing receives from the pressure sensor 5 a value relating to the pressure level in the gas chamber 1, i.e. a value relating to the second pressure. In the case shown, Figure 2 the level height Y2 in the fuel tank filler pipe 6 is essentially equal to the level height X2 in the fuel tank 2, but it is also possible to determine the value of the second pressure at the point in time at which the level heights just begin to match. The matching of the levels takes place on the basis of the pressure drop in the gas chamber 1. The pressure drop in the gas chamber 1 is adjusted quickly, whereas the matching of the levels is delayed with respect to the pressure drop.

[0087] The device 7 can determine a difference value from the two measured values of the first pressure and the second pressure. If this difference value exceeds a pre-set threshold value, the device 7 determines that the filler cap does not close the filler neck. The device 7 can then transmit a signal to the signal generator 8 via the data line 12. In response, the signal generator 8 outputs an output signal, for example an optical signal, such as an activated indicator light (for example with a stylized symbol), which informs the user that the filler cap does not fluid-tightly close the filler neck, or that the tank cap does not fluid-tightly close the filler neck.

[0088] In contrast to the situation shown in Figure 2 Figure 3 The fuel system is shown in a state in which the tank cap 13 is fluid-tightly attached.

[0089] Figure 3 In particular, the fuel system is shown after the recirculation line valve 9 has been opened O by the device 7 via the signal emitted via the data line 11. The gas chamber 1 establishes a gaseous connection to the filler neck 4 via the opened recirculation line 3, but it is not open to the atmosphere due to the attached tank cap 13. As a result, the pressure drop in the gas chamber 1 over a pre-set period of time is much smaller than Figure 2 the situation described in Figure 2 In the situation shown, the gas chamber is at least indirectly connected to the atmosphere. In this case, the liquid in the fuel tank 2 and the liquid in the tank filler pipe are subjected to the same or at least approximately the same pressure. As a result, the liquid level height Y1 in the tank filler pipe 6 matches the liquid level height X1 in the fuel tank 2 until it reaches the same or almost the same level.

[0090] At the point in time shown in Figure 3 the data processing device 7 receives a value from the pressure sensor 5 regarding the pressure level in the gas chamber 1, a value regarding the second pressure.

[0091] The device 7 can determine a difference value from the two measured values of the first pressure and the second pressure. The device 7 is configured in such a way that it determines that this difference value is below a pre-set threshold value. On the basis of this, the device 7 determines that the filler cap closes the filler neck, and can optionally output a closed state value, which indicates that the filler cap closes the filler neck. It is thus not necessary to inform the user of this result, or this information can be stored in a first alternative, or, in a second alternative, the device 7 can transmit a signal to the signal generator 8 via the data line 12. In response, the signal generator 8 outputs an output signal, for example an optical signal, such as an activated indicator light (for example with a stylized symbol), which informs the user that the filler cap fluid-tightly closes the filler neck, or that the tank cap fluid-tightly closes the filler neck.

[0092] Figure 4 ​A fuel tank system is shown in the form of an ORVR system.

[0093] The fuel tank 2 has a refueling vent valve 14 which establishes a fluid connection from the gas chamber 1 of the fuel tank 2 to an activated carbon filter 15 by means of a line. The activated carbon filter 15 is connected by means of another line to a purge valve 17 which is connected to a discharge line. The activated carbon filter 15 is connected by means of another line to a leak detection unit 16. An alternative without a leak detection unit 16 with an EVR system (external vapor recovery system) is not shown here. In the present case, the recirculation valve 9 and the refueling vent valve 14 share their delivery line 3, apart from a section of the line which branches off immediately adjacent to the respective valves 9 and 14. The valves 9 and 14 can also have separate delivery lines.

[0094] Legend of the figures

[0095] 1: gas chamber

[0096] 2: fuel tank

[0097] 3: recirculation line

[0098] 4: filler neck

[0099] 4a: part of the fuel filler cap device fixedly attached in the filler neck

[0100] 5: pressure sensor

[0101] 6: fuel tank filler tube

[0102] 7: data processing device

[0103] 8: signal generator

[0104] 9: (recirculation line) valve

[0105] 10: data line between valve and data processing device

[0106] 11: data line between pressure sensor and data processing device

[0107] 12: data line between data processing device and signal generator

[0108] 13: fuel tank cap (tank cap); part of the fuel filler cap device reversibly attached in the filler neck

[0109] 14: refueling vent valve

[0110] 15: activated carbon filter

[0111] 16: leak detection unit

[0112] 17: Exhaust valve

[0113] G: Valve closed

[0114] O: Valve open

Claims

1. A method for detecting whether a fuel filler cap of a motor vehicle is closed, implemented by a data processing device (7), comprising the following steps: - Transmit a signal to interrupt the recirculation line (3) from the fuel tank (2) of the motor vehicle to the refueling connector (4) of the fuel tank (2), thereby interrupting the connection between the gas chamber (1) of the fuel tank (2) and the atmosphere; - Obtain the value of the first pressure present in the gas chamber (1) of the fuel tank (2); - Output a signal to open the recirculation line (3); - Obtain the value of the second pressure present in the gas chamber (1) of the fuel tank (2); - If the second pressure is less than the first pressure by a certain preset value, it is determined that the fuel filler cap is not closed and a value about the closed state is output, the closed state indicating that the fuel filler cap does not close the filler connector (4).

2. The method according to claim 1, characterized in that, The method of claim 1 shall be implemented after the following is determined. i) The fuel tank (2) has been filled. ii) The engine for vehicle movement has been started. iii) The fuel tank flap on the fuel filler cap is closed, or iv) The refueling process has been defined as completed by the data processing device; Or there may be two, three, or four of the conditions i) to iv).

3. The method according to claim 2, characterized in that, Step i) includes: determining that the liquid level in the fuel tank (2) has increased, and determining that the liquid level in the fuel tank (2) no longer increases.

4. The method according to claim 3, characterized in that, Step i) includes: determining that the fuel tank (2) is full to its maximum capacity.

5. The method according to claim 2, characterized in that, Step i) includes: determining that the fuel level in the fuel tank filling pipe (6) of the fuel tank (2) is higher than the fuel level in the fuel tank (2).

6. The method according to any one of the preceding claims, characterized in that, The value of the first pressure is higher than the atmospheric pressure of the motor vehicle by 250 Pascals, 500 Pascals, 1000 Pascals, or 2000 Pascals.

7. The method according to any one of the preceding claims, characterized in that, The second pressure is 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% lower than the first pressure.

8. The method according to any one of the preceding claims, characterized in that, The output indicates the closed state of the fuel filler cap not closing the filler connector (4), which causes the output of a signal that is a visual, auditory or tactile signal in the passenger interior space.

9. The method according to claim 8, characterized in that, The signal is a visual alarm signal displayed on or in the vehicle's dashboard.

10. A computer program product comprising a plurality of instructions, which, when executed by a computer, cause the computer to perform the method according to any one of claims 1-9.

11. A computer-readable storage medium comprising a plurality of instructions, which, when executed by a computer, cause the computer to perform the method according to any one of claims 1-9.

12. A data processing apparatus (7) comprising components for implementing the method according to any one of claims 1-9.

13. A system for detecting whether a fuel filler cap of a motor vehicle is closed, comprising: A fuel tank (2) having a fuel tank filling pipe (6) and a filling connector; A recirculation line (3) leads from the fuel tank (2) to the filling connector (4) of the fuel tank (2); A sensor for detecting the pressure in the gas chamber (1) of the fuel tank (2); The sealing device on the filling connector (4) is used to isolate the fuel tank (2) from the atmosphere; and The data processing apparatus (7) according to claim 12.

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