Cleaning a lidless tank system using engine vacuum.

Abstract

Procedures, encompassing the following: In response to a leak detected after refueling in a vehicle (100) with an engine (108) and a lidless tank system (120), cleaning (308) of the lidless tank system (120) using engine vacuum.

Description

[0001] Fuel systems for engines, such as diesel or gasoline engines, may include capless fuel filler necks on a fuel filler line, connected to the tank for refueling. These capless fuel filler necks may incorporate sealing flaps or tabs that remain closed to seal the fuel system without a cap. A sealing flap on a capless fuel filler neck can be opened, for example, by inserting a fuel nozzle into the filler neck for refueling. Capless tank configurations can be used in vehicles to reduce evaporative emissions and simplify the refueling process.

[0002] Leakage testing can be performed on fuel evaporative emissions systems to detect minor leaks and reduce emissions. In some approaches, if a leak is detected in a vehicle with a capless fuel tank system after refueling, a message can be sent to the vehicle operator instructing them to manually clean the capless fuel tank unit. For example, a fuel funnel may be on board a vehicle with a capless fuel tank system, and in response to a leak detected after refueling, the vehicle operator may be instructed to manually clean the capless unit by inserting the funnel into the unit to remove dirt, salt, leaves, or other contaminants that may have entered the capless unit and caused the leak.If the leak is still present after manually cleaning the lidless unit, a diagnostic code can be set indicating the reduced functionality of the evaporative emission system.

[0003] US Patent 7,163,037 B2 describes a capless fuel tank system in which the pre-tensioned closure is provided with an elastic seal and is mounted on a movable support structure. This system is designed to use an applied vacuum for leak testing. US Patent 2006 O 237,472 A1 describes another capless fuel tank system. This system is designed to use an applied vacuum to perform a vehicle-specific leak test for the capless fuel tank filler neck closure to check for leaks.

[0004] However, the inventors of the present device recognized that approaches based on manually cleaning lidless units when a leak is detected are intrusive and require a tool, such as a funnel, which can be used incorrectly. Furthermore, such manual cleaning methods can increase the release of fuel vapors into the environment if the operator inserts the cleaning tool into the lidless unit.

[0005] To at least partially solve these problems, a method according to the invention for a vehicle with an engine and a capless fuel tank system comprises the features of claim 1, i.e., cleaning the capless fuel tank system using engine vacuum in response to a leak detected after refueling. For example, cleaning the capless fuel tank system using engine vacuum can be performed in response to the fact that no leak is detected before refueling and a leak is detected after refueling. Furthermore, in some examples, if a leak is still detected after cleaning the capless fuel tank system using engine vacuum, a request can be sent to a vehicle operator to clean the capless fuel tank system manually.

[0006] In this way, according to the invention, an engine vacuum is used to remove contaminants that have entered a lidless unit without the need for a manual, intrusive tool. Furthermore, since an engine vacuum is used in such an approach, fuel vapors can be retained inside the tank, thus potentially reducing fuel emissions during the cleaning process.

[0007] The above-mentioned and further advantages and features of the present description will be readily apparent from the following detailed description, either on its own or in conjunction with the accompanying drawings.

[0008] It is understood that the foregoing summary is provided to present, in simplified form, a selection of concepts that are described in more detail in the full description. It is not intended to identify any decisive or essential features of the claimed invention, the scope of which is clearly defined by the claims following the full description. Furthermore, the claimed invention is not limited to implementations that eliminate the disadvantages mentioned above or in any part of this disclosure. Fig. Figure 1 shows a schematic representation of an exemplary vehicle system with a lidless fuel filling system. Fig. Figure 2 shows an exemplary vehicle system with a system for reducing fuel emissions. Fig. Figure 3 shows an exemplary method for cleaning a lidless tank system using engine vacuum. Fig. Figure 4 shows an engine operating diagram illustrating an exemplary method for cleaning a lidless tank system using a vacuum in the engine manifold.

[0009] The following description concerns systems and procedures for cleaning a lidless tank system in a vehicle, such as those described in Fig. 1 and Fig. The two exemplary vehicles shown are examples. As described below. Fig. As shown in Figure 3, if a leak occurs in a lidless tank system after refueling, contaminants may have entered the lidless unit during refueling. Engine vacuum can be used to expel or remove these contaminants. In this way, engine vacuum can be used to remove dirt that has entered the lidless unit without relying on a manual, intrusive tool. Furthermore, because this approach uses engine vacuum, fuel vapors can be retained inside the tank, potentially reducing fuel emissions during the cleaning process.

[0010] In Fig. Figure 1 is a schematic representation of an exemplary vehicle system, generally labelled 100. The vehicle 100 may include a chassis 102, an axle 104 with wheels 106, and an engine 108. The engine 108 may be a diesel engine in one example and a gasoline engine in other examples. Furthermore, although not shown, the vehicle 100 may also include a transmission, a cab, or other components.

[0011] The vehicle 100 may further include an exhaust system 110. The exhaust system may include an exhaust pipe 112 leading to one or more exhaust aftertreatment devices, e.g., the devices 114. Sections of the exhaust system, such as the pipe 112, may be coupled to an exhaust manifold of the engine 108 in such a way that exhaust gas is directed from the exhaust manifold to the pipe 112.

[0012] The vehicle 100 may further include a fuel system 116. The fuel system 116 may include one or more fuel storage tanks 118 for storing fuel on board the vehicle. For example, the fuel tank 118 may store one or more liquid fuels, in particular gasoline, diesel, alcoholic fuel, or mixtures thereof. The fuel tank 118 may be connected to the engine 108 via a fuel supply line (not shown) to supply fuel to the engine 108. The fuel system 116 may include a fuel evaporation emission reduction system 151, which can be used to reduce evaporation emissions from the fuel system 116. An example of an emission reduction system is described below with reference to Fig. 2 described in more detail.

[0013] A fuel filling line 122 can be connected to the fuel tank 118 to supply fuel to the fuel tank 118 during refueling. A capless fuel filling system 120 can be connected to the filling line 122. A capless fuel filling system can include a sealing element that remains closed to seal the fuel system without a cap. A sealing element in a capless fuel filling system can be opened for refueling, for example, by inserting a dispensing nozzle, such as the dispensing nozzle 138 of the fuel dispensing device 134, into the fuel filling port 124. The capless fuel filling system 120 includes a capless fuel filling port 124, which contains a sealing flap or tab 128 that is held in place by one or more latches or seats 130 that remain closed to seal the fuel system without a fuel cap.The fuel filler neck 124 can penetrate at least partially into an outer surface 170 of the vehicle 100 in such a way that fuel can be added to the fuel tank from an external fuel source. For example, the fuel can be added to the fuel tank 118 at a fuel pump station using a fuel dispensing device 134.

[0014] If a nozzle is inserted into the lidless tank system during refueling, contaminants such as dirt, salt, leaves, or other impurities can enter the lidless unit, preventing it from being completely sealed after the nozzle is removed. These contaminants can cause leaks in the emission control system, which can be detected by emission control leak detection programs. As further explained below, Fig. As described in section 3, in response to a leak detected after refueling, under certain conditions an engine vacuum may be used to assist in the removal of contaminants that have entered the lidless unit.

[0015] In some examples, the capless fuel filling system 120 may include a misfueling protection device 126. The misfueling protection device 126 may be designed such that the sealing flap 128 in the capless fuel filler neck is prevented from being opened by nozzles or spouts of the wrong size, in order to reduce the occurrence of misfueling. For example, in a diesel engine, a misfueling protection device may be designed such that the capless filler neck can be opened by a standard-sized diesel fuel nozzle, but it prevents the capless filler neck from being opened by a gasoline nozzle, which may be smaller than a diesel nozzle.As another example, in a petrol engine, misfuelling protection can be designed in such a way that opening the capless filler neck with a standard-sized petrol nozzle is permitted, while opening the capless filler neck with a diesel nozzle is prevented.

[0016] In some examples, the vehicle 100 may include a vehicle-specific funnel 181 that can be used to refuel the fuel tank 118 under conditions where a standard nozzle, such as the nozzle 138, is not available. The funnel 181 may, for example, be stowed inside the vehicle 100, allowing an operator to refuel the fuel tank 118 using a non-standard fuel source, such as a fuel container, etc. Under certain conditions, the funnel 181 may be used to manually clean the lidless tank system of debris if a leak is detected after refueling. For example, if a small leak is detected after refueling, a message may be sent to the vehicle operator; for instance, it may state that the fuel tank is full.A message will appear on the instrument cluster instructing the operator to use the provided funnel and insert it several times into the lidless unit to remove any contaminants that may be present. If the leak persists after manually cleaning the lidless unit, a warning may be sent to the vehicle's diagnostic system or emissions control system to indicate a malfunction or leak in the lidless unit, allowing for maintenance to be performed. For example, one or more diagnostic codes may be set to indicate the presence of a leak.

[0017] Fig. Figure 2 shows another schematic representation of a vehicle system 206. The vehicle system 206 includes an engine system 208, which is coupled to an emissions reduction system 151 and a fuel system 218. The emissions reduction system 151 includes a fuel vapor canister 222, which can be used to capture and store fuel vapors.

[0018] The engine system 208 can include a multi-cylinder engine 210 230. The engine 210 includes an intake manifold 223 and an exhaust manifold 225. The intake manifold 223 includes a throttle valve 262, which is in fluid communication with the intake manifold 244 via an inlet passage 242. The exhaust manifold 225 includes an exhaust manifold 248, which leads to an exhaust port 235 that discharges the exhaust gas into the environment. The exhaust manifold 225 can include one or more emission reduction devices 270, which are mounted in a closely coupled position in the exhaust system. The one or more emission reduction devices can include a three-way catalytic converter, a NOx storage catalyst, a diesel particulate filter, an oxidation catalyst, etc. It goes without saying that the engine may contain other components, such as a variety of valves and sensors.

[0019] The fuel system 218 can include a fuel tank 220 coupled to a fuel pump system 221. The fuel pump system 221 can include one or more pumps to pressurize the fuel, which is then supplied to the injectors of the engine 210, such as the exemplary injector 266 shown. Although only a single injector 266 is shown, additional injectors are provided for each cylinder. It is understood that the fuel system 218 can be a system without fuel return, a system with fuel return, or one of various other types of fuel systems.

[0020] The vapors generated in the fuel system 218 can be routed via a vapor return line 231 to an emission reduction system 151, which includes a fuel vapor canister 222, before being discharged to the engine intake manifold 223. The vapor return line 231 can be connected to the fuel tank 220 via one or more lines and can include one or more valves to isolate the fuel tank under certain conditions. For example, the vapor return line 231 can be connected to the fuel tank 220 via one or more lines or a combination of lines 271, 273, 275. Furthermore, in some examples, one or more tank isolation valves can be included in the return line 231 or in the lines 271, 273, 275.Among other functions, the tank isolation valves can allow a low or negative pressure to be maintained in the fuel vapor canister of the emission reduction system without increasing the rate of fuel evaporation from the tank (which would otherwise occur if the pressure in the fuel tank were reduced). For example, line 271 can include a grade vent valve (GGV) 287, line 273 a fill limit venting valve (FLVV) 285, and line 275 a grade vent valve (GVV) 283. Furthermore, in some examples, the return line 231 can be coupled to the capless fuel filling system 120 in such a way that, under certain conditions, as described in more detail below, engine vacuum can be used to clear impurities or other blockages in the capless tank system.

[0021] As described above, the capless fuel filling system 120 is coupled to the fuel tank 220 via a fuel filling line or fuel filling nozzle 122 and may include a capless tab 128 and a seat 130 to seal the capless unit when no dispensing nozzle is fitted within it. However, as described in more detail below, under certain conditions during refueling, dirt or other contaminants may enter the capless unit, potentially leading to leaks in the system.

[0022] A fuel tank pressure sensor (FTPT) 291 or a fuel tank sensor can be provided between the fuel tank 220 and the fuel vapor canister 222 to provide an estimate of the fuel tank pressure and for leak detection when the engine is off. Alternatively, the fuel tank pressure sensor can be located in a vapor return line 231, a drain line 228, a vent line 227, or elsewhere in the emission reduction system 151 without affecting its ability to detect leaks when the engine is off.

[0023] The emission reduction system 151 may include one or more emission reduction devices, such as one or more fuel vapor canisters 222 filled with a suitable absorbent, wherein the canisters are designed to temporarily capture fuel vapors (including vaporized hydrocarbons) and "run-on losses" (i.e., fuel that evaporates during vehicle operation) during fuel tank refueling operations. In one example, the absorbent used is activated carbon. The emission reduction system 151 may further include a vent line 227 that directs gases from the canister 222 to the environment when fuel vapors from the fuel system 218 are stored or captured.The vent line 227, when releasing stored fuel vapors from the fuel system 218 via the drain line 228 and a drain valve 261 to the engine intake manifold 223, can also allow fresh air to be drawn into the canister 222. The drain valve 261 may, for example, normally be closed, but can be opened under certain conditions so that a vacuum is provided from the engine intake manifold 244 for the lidless tank system. Although this example shows the vent line 227 connected to fresh, unheated air, various modifications can also be used. The flow of air and vapors between the canister 222 and the environment can be controlled by the operation of a canister venting solenoid (not shown) coupled to the canister venting valve 229. The canister venting valve 229 may, for example, normally be open.Under certain conditions, the vent valve 229 can be closed to isolate the emission reduction system from the environment.

[0024] The vehicle system 206 can also include a control system 214. The control system 214 is represented as receiving information from several sensors 216 (various examples are described here) and sending control signals to several actuators 281 (various examples are described here). For example, the sensors 216 can include an exhaust gas sensor 237, which is located upstream of the emission control device, a temperature sensor 233, a pressure sensor 237, and a pressure sensor 291. Further sensors, such as pressure, temperature, air / fuel ratio, and composition sensors, can be coupled to the vehicle system 206 at various points, as described in more detail here. As another example, the actuators can include a fuel injector 266, a valve 229, a throttle valve 262, and a valve 261. The control system 214 can include a controller 212.The controller can receive input data from various sensors, process this data, and trigger the actuators in response to the processed input data, based on programmed commands or code. Examples of control programs are listed here with reference to... Fig. 3 described.

[0025] The emission reduction system 151 operates to store vaporized hydrocarbons (HC) from the fuel system 218. Under certain operating conditions, such as during refueling, fuel vapors present in the fuel tank can be displaced when liquid is added. The displaced air and / or fuel vapors can be routed from the fuel tank 220 to the fuel vapor canister 222 and then released into the environment through the vent line 227. In this way, a larger quantity of vaporized HC can be stored in the canister 222. During subsequent engine operation, the stored vapors can be returned to the incoming intake air by means of the intake manifold vacuum. Specifically, the canister 222 can draw in fresh air through the vent line 227 and release the stored HC into the engine intake manifold for combustion.Such draining processes can occur under selected engine operating conditions.

[0026] Fig. Figure 3 shows an exemplary method 300 for cleaning a lidless tank system using engine manifold vacuum. If the system for reducing evaporative emissions 151, for example, is free of leaks before refueling but leaks after refueling, this may indicate that contaminants such as dirt, salt, leaves, and / or other impurities have entered between the lidless flap and the seat and are causing the leak. Instead of relying on a special tool to manually clean the lidless unit, the lidless unit can be cleaned automatically using engine vacuum.

[0027] In 302, procedure 300 involves determining whether a lidless tank system is in use. Procedure 300 can be used, for example, in a vehicle such as the one described in Fig. 1. Vehicle 100 shown, which includes a lidless tank system, such as the lidless tank system 120. If a lidless tank system is in use at 302, procedure 300 continues with 303.

[0028] In procedure 300, 303 involves determining whether a draining operation takes place. For example, a fuel vapor canister, such as canister 222, may be drained during engine operation under selected conditions. Canister 222 may be drained, for example, in response to a quantity of fuel stored in the canister exceeding a limit value. The draining conditions may also be based on engine operating conditions, such as engine speed, engine load, the extent of the vacuum available for the canister, and so on. If a draining operation takes place in procedure 303, procedure 300 continues with 305.

[0029] In procedure 300, part of the 305 process involves draining the canister. The fuel vapor canister 222 can be drained, for example, by opening the vent valve 229 or by keeping the vent valve 229 open and opening the drain valve 261, so that the engine vacuum can draw fuel vapors from the canister 222 into the engine. After draining is complete, the drain valve 261 can be closed and the vent valve 229 can be kept open.

[0030] If no draining operation occurs at step 303, then procedure 300 continues with step 304. At step 304, procedure 300 involves determining whether a refueling operation has taken place. Determining that a refueling operation has taken place can be based on the condition of a switched-off engine, one or more sensors in the fuel system, a change or increase in the fuel level, etc. If a refueling operation has taken place at step 304, procedure 300 continues with step 306.

[0031] In 306, procedure 300 involves determining whether a leak currently exists and whether no leak was detected prior to refueling. The leak test can be performed, for example, immediately before refueling by sealing the evaporation emission reduction system and monitoring pressure changes in the system to determine if a leak is present. After refueling, the leak test can be performed again to determine if a leak has been detected. A leak introduced into the evaporation emission reduction system after refueling may indicate that contaminants were introduced into the lidless tank unit during refueling, for example, by inserting the nozzle into the lidless unit.Therefore, it may be desirable to clean the lidless unit if no leakage was detected before refueling and if a leakage was detected after refueling, in order to remove the contaminants.

[0032] In the case of 308, procedure 300 involves cleaning the capless tank system using engine vacuum. Cleaning the capless tank system using engine vacuum can be performed under conditions where the fuel vapor canister is not drained. For example, in response to a leak detected in the capless tank system after refueling, vacuum can be supplied to the capless tank system from an intake tract of the engine, such as the intake manifold 244. The emission reduction system can be isolated from the environment, for example, by temporarily closing a fuel vapor canister vent valve, such as valve 229, and opening a fuel vapor canister drain valve, such as valve 261, to supply engine vacuum to the capless unit during this period.

[0033] In some examples, the duration for which engine vacuum is supplied to the capless unit may be a fixed time period. In other examples, the duration may be based on engine operating conditions, such as engine speed, engine load, the level of vacuum present in the engine's intake tract, etc. For example, engine vacuum may be supplied to the capless unit when the level of vacuum in the engine's intake tract exceeds a certain threshold, such as greater than 20 inH2O, to ensure that sufficient vacuum is supplied to the capless unit to open the capless flap, allowing ambient air to be drawn into the capless unit to draw contaminants into the fuel tank and clean the unit.The engine vacuum can, for example, force contaminants in the lidless unit into the fuel tank, causing the lidless unit to reseal itself tightly. In some cases, the engine vacuum can be supplied to the lidless unit to periodically clean the unit under specific conditions. For example, the engine vacuum can be supplied to the lidless unit to clean the unit according to a periodic maintenance schedule.

[0034] In 310, procedure 300 involves determining whether a leak still exists. For example, if a leak is still detected in the lidless tank system after attempting to automatically clean the lidless unit using engine vacuum, in some examples, engine vacuum can be applied again under conditions of increased engine vacuum to attempt to remove the contaminants. Thus, in 311, for example, procedure 300 can involve determining whether the cleaning of the lidless unit using engine vacuum should be repeated. Cleaning using engine vacuum in 308, for example, can be performed several times until no further leakage is detected.Thus, procedure 300 can go back to 306 if, at 311, the cleaning of the lidless unit is determined to be repeated using a motor vacuum in order to provide a vacuum for the lidless unit from the motor again and to perform a subsequent leak test.

[0035] However, if a leak persists after one or more attempts at cleaning using engine vacuum, it may be desirable to inform a vehicle operator that the coverless unit should be cleaned manually, e.g., using funnel 181 or another tool. Thus, if a leak is still present at step 310 and it has been determined at step 311 not to repeat the cleaning of the coverless unit, procedure 300 continues with step 312.

[0036] In 312, procedure 300 involves informing an operator about the need for manual cleaning of the lidless tank system. For example, in response to a leak detected after cleaning the lidless unit using engine vacuum, a prompt may be generated and sent to a vehicle operator to manually clean the lidless tank system. For example, information may be displayed on an instrument cluster in the vehicle, prompting the driver to insert a funnel or other tool into the lidless unit to remove any debris. In some examples, the lidless unit may be monitored to determine whether a manual cleaning operation has taken place. A manual cleaning operation may be detected, for example, based on an engine start / stop condition and / or on one or more sensors in the lidless tank system, such as...a sensor that is coupled to a tab or sealing flap in the lidless unit.

[0037] In procedure 300, 314 involves determining whether a leak still exists. For example, if a leak persists after engine vacuum has been applied to attempt to remove contaminants from the lidless unit, and after the vehicle operator has attempted to manually clean the lidless unit, the detected leak may indicate a persistent leak in the lidless unit. Thus, if a leak persists in procedure 314, 300 proceeds to 316.

[0038] For 316, procedure 300 involves setting a diagnostic code to indicate a persistent leak. In response to a leak detected after a period following the sending of a manual cleaning request to the vehicle operator, a capless tank system malfunction may be indicated. This malfunction may be indicated, for example, after the capless tank system has been manually cleaned by the vehicle operator. For instance, a manual cleaning operation may be detected in the capless tank system, and in response to a leak detected after the manual cleaning operation, a capless tank system malfunction may be indicated. For example, indicating a capless tank cleaning system malfunction may involve setting a diagnostic code in an in-vehicle diagnostic system so that maintenance can be performed.

[0039] Fig. Figure 4 shows exemplary engine operating curves 402, 404, and 406, which represent an exemplary procedure, e.g., the procedure 300 described above for cleaning a lidless tank system using engine vacuum. Figure 402 shows Fig. 4. Engine operation, e.g., whether the engine is on or off, during leak testing, refueling, and cleaning of the lidless unit. At 404, this is indicated. Fig. 4 the position of a vent valve, e.g., valve 229, located between a fuel vapor canister 222 and the environment, during leak testing, refueling, and cleaning of the lidless unit. At 404, it shows Fig. 4 the position of a drain valve, e.g. the drain valve 261, which is located between a fuel vapor canister 222 and an intake tract of the engine, during leak testing, refueling and cleaning of the lidless unit.

[0040] As in Fig. As shown in Figure 4, the engine may be switched off or shut down at time t0. However, before time t0, the engine may be running, and the vent valve may be open and the drain valve closed. For example, during engine operation, the vent valve may be normally open and the drain valve normally closed.

[0041] After the engine is switched off at time t0, a leak test can be performed on the fuel evaporative emissions system at time t1. At t1, for example, the vent valve may be closed, while the drain valve remains closed from time t1 until time t2, during which time the leak test is performed. During this initial leak test, between time t1 and time t2, no leak may be detected. After the initial leak test concludes at t2, the vent valve can be opened, while the drain valve remains closed. At time t3, after time t2, refueling can take place. While the engine is switched off, a vehicle operator can, for example, add fuel to the fuel tank at time t3.Refueling can take place without starting the engine between times t2 and t3, following the initial leak test between times t1 and t2. Immediately after refueling, a second leak test can be performed at time t4, between times t4 and t5. During this second leak test, the vent valve can be closed, while the drain valve remains closed. This second leak test can also be performed at time t6 before starting the engine. For example, a leak can be detected through this second leak test.

[0042] After the second leak test ends at time t5, the engine can be restarted at time t6. Since no leak was detected during the first leak test, but a leak was detected during the second leak test after refueling, the lidless unit can be cleaned using engine vacuum between times t7 and t8 while the engine is running at time t7. At time t7, the vent valve can be in a closed position, while the drain valve can be in an open position, thus providing engine vacuum for cleaning the lidless unit. After the cleaning process of the lidless unit ends at time t8, the vent valve can be open and the drain valve closed.

Claims

[1] Procedure, comprising the following: In response to a leak detected after refueling in a vehicle (100) with an engine (108) and a lidless tank system (120), cleaning (308) of the lidless tank system (120) using engine vacuum. [2] Method according to claim 1, wherein the cleaning (308) of the lidless tank system (120) is carried out using a motor vacuum in response to the fact that no leak is detected immediately before the refueling process and a leak is detected after the refueling process (306). [3] The method of claim 1, further comprising: in response to a leak detected after cleaning (308) the lidless tank system (120) using engine vacuum (306), generating (312) a request to a vehicle operator to manually clean the lidless tank system (120). [4] The method of claim 3, further comprising: in response to a leak which was detected after a period of time following the creation (312) of a request to the vehicle operator (314), an indication of a reduction in the functionality of the lidless tank system (120). [5] Method according to claim 4, wherein indicating a functional impairment of the lidless tank system (120) includes setting a diagnostic code (316) in a vehicle-internal diagnostic system. [6] Method according to claim 1, wherein the cleaning (308) of the lidless tank system by means of an engine vacuum comprises closing a fuel vapor canister vent valve (229) and opening a fuel vapor canister drain valve (261) for a period of time. [7] Method according to claim 6, wherein the fuel vapor canister vent valve (229) is arranged between a fuel vapor canister (222) and the environment and the fuel vapor canister drain valve (261) is arranged between the fuel vapor canister (222) and an intake tract of the engine. [8] Method according to claim 1, wherein the cleaning (308) of the lidless tank system (120) is carried out using an engine vacuum in response to a vacuum in the intake tract of the engine that is greater than a limit value. [9] Method for a vehicle (100) with an engine (108) and a lidless tank system (120), comprising the following: Providing a vacuum from an intake tract of the engine (108) to a lidless tank system (120) in response to a leak detected after a refueling operation in the lidless tank system (120). [10] Method according to claim 9, wherein the provision of a vacuum from an intake tract of the engine (108) for the lidless tank system (120) is carried out in response to the fact that no leak was detected before the refueling process and a leak was detected after the refueling process (306).

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