Method for operating a motor vehicle fuel tank arrangement and corresponding fuel tank arrangement

Abstract

The invention relates to a method for operating a fuel tank arrangement (1) of a motor vehicle, wherein the fuel tank arrangement (1) has a fuel tank (2), a hydrocarbon filter (3) and a pump (4), wherein the fuel tank (2) is connected via a tank shut-off valve (5) in flow technology to the hydrocarbon filter (3), the hydrocarbon filter (3) is connected on the one hand via the pump (4) in flow technology to an environment (8) outside the fuel tank arrangement (1) and on the other hand via a flushing valve (9) in flow technology to an intake tract (10) of an internal combustion engine (11). It is provided that a first leak check operating mode is carried out when a pressure present in the fuel tank (2) is greater than a pressure threshold value, in which the shut-off valve (6) arranged in flow technology between the pump (4) and the environment (8) is closed and the tank shut-off valve (5) is opened, and subsequently during a check period the pressure in the fuel tank (2) is measured by means of a pressure sensor (14) arranged in the fuel tank (2), and when a pressure difference of a pressure drop of the pressure within a specific period exceeds a difference threshold value, a leak of the fuel tank arrangement (1) is identified. The invention also relates to a fuel tank arrangement (1) for a motor vehicle.

Description

Technical Field

[0001] This invention relates to a method for operating a fuel tank device for a motor vehicle, wherein the fuel tank device includes a fuel tank, a hydrocarbon filter, and a pump. The fuel tank is connected to the hydrocarbon filter via a tank shut-off valve in a flow technique. The hydrocarbon filter is connected, on one hand, to the external environment of the fuel tank device via the pump in a flow technique, and on the other hand, to the intake manifold of an internal combustion engine via a flushing valve in a flow technique. The invention also relates to a fuel tank device for a motor vehicle. Background Technology

[0002] For example, document DE 10 2015 221 536 A1 is known from the prior art. This document describes a device for diagnosing fuel tank leaks in a motor vehicle, wherein the fuel tank is connected to the intake manifold of an internal combustion engine via an exhaust line, wherein the internal combustion engine can be loaded by means of a pressure generator, wherein the fuel tank can be supplied with compressed air by means of pressure generated in the pressure generator, wherein a valve is arranged in the exhaust line through which compressed air can be supplied to the fuel tank, wherein the valve can be closed after pressure is applied, thereby disconnecting the exhaust line, and wherein a pressure sensor for diagnosing tank leaks is arranged in the exhaust line or the fuel tank.

[0003] Furthermore, document DE 10 2012 007 214 A1 describes a device for sealing inspection of a fuel system in a motor vehicle. This device has a first memory and a second memory, each having a storage medium for irreversibly combining volatile fuel components. The first and second memories are connected to a fuel tank via at least one exhaust line and to the intake manifold of an internal combustion engine via at least one intake line. Here, the second memory has a smaller storage volume than the first memory and can be subjected to a flow of volatile fuel components from the fuel tank through the exhaust and intake lines to the internal combustion engine during sealing inspection. A throttling element for reducing the flow cross-sectional area is arranged upstream of the second memory along the flow direction. Summary of the Invention

[0004] The object of the present invention is to provide a method for operating a motor vehicle fuel tank device that has advantages over known methods, particularly for performing fuel tank device sealing checks more reliably with lower energy requirements.

[0005] This is achieved according to the invention by a method for a fuel tank device for operating a motor vehicle having the features of the scheme described below. Here, a first leak detection operation mode is performed when the pressure present in the fuel tank exceeds a pressure threshold. In the first leak detection operation mode, a shut-off valve arranged between the pump and the external environment in the flow technology is closed, and the tank shut-off valve is opened. Subsequently, during the inspection period, the pressure in the fuel tank is measured using a pressure sensor arranged in the fuel tank. When the pressure difference of the pressure drop within a specific period exceeds a difference threshold, a leak in the fuel tank device is identified.

[0006] Advantageous designs and suitable improvements of the present invention are described in other technical solutions.

[0007] The fuel tank assembly is preferably an integral part of the motor vehicle, but it can also be understood to exist separately from the motor vehicle. The fuel tank assembly includes at least a fuel tank, a hydrocarbon filter, and a pump as its basic components. Additional components include a tank shut-off valve and a flushing valve. The fuel tank is used to temporarily store fuel, which is used at least temporarily to operate the drive unit of the motor vehicle. The drive unit is used to drive the motor vehicle, that is, to provide the drive torque designed to drive the motor vehicle. The drive torque is generated by the drive unit via a drive unit, for which fuel taken from the fuel tank is delivered.

[0008] The fuel tank is designed as a so-called pressure tank. This means that it is typically sealed, i.e., sealed by a tank shut-off valve arranged between the fuel tank and the hydrocarbon filter in a flow process. Depending on the environmental conditions of the fuel tank unit, overpressure may occur in the fuel tank, caused by fuel transferring to the gas phase, particularly through evaporation and / or vaporization. Overpressure is understood as the pressure present in the fuel tank being higher than the pressure present in the external environment of the fuel tank unit. If the pressure present in the fuel tank is mentioned within the scope of this specification, then this pressure can be understood as an absolute pressure. However, preferably, the pressure exists as a relative pressure relative to a reference pressure, wherein preferably, the pressure in the external environment is used as the reference pressure.

[0009] In this flow technology, a fuel injection line connects to a fuel tank. The fuel injection line has an opening on its side opposite the fuel tank, which can be closed by a tank cover. Fuel can be supplied to the fuel tank, for example, from a tap, via the fuel injection line. For this to be done, the tank opening must be opened, and the tank cover must be opened or moved relative to the opening. Fuel can then be introduced into the fuel injection line through the tank opening and into the fuel tank via the fuel injection line. If overpressure exists in the fuel tank when the tank cover is open, the overpressure decreases abruptly through the tank opening towards the external environment when the tank cover is opened.

[0010] To avoid this, it is preferable to vent the fuel tank periodically, especially before opening the tank cover. For this purpose, the tank shut-off valve is opened, allowing the fluid present in the fuel tank—specifically composed of air and gaseous fuel or hydrocarbons—to flow towards the external environment of the fuel tank assembly. The fluid flowing towards the external environment passes through a hydrocarbon filter. The hydrocarbon filter removes the fuel or hydrocarbons present in the fluid, preventing them from escaping into the external environment. The hydrocarbon filter preferably has a filter body made of activated carbon and / or is at least partially composed of activated carbon. The fuel or hydrocarbons filtered out from the fluid are temporarily stored in the hydrocarbon filter. In this sense, fuel or hydrocarbons are reversibly introduced into the hydrocarbon filter. Therefore, the hydrocarbon filter can also be referred to as a temporary hydrocarbon storage device.

[0011] Because hydrocarbon filters have only a limited capacity to absorb fuel or hydrocarbons, they require temporary flushing. The negative pressure present in the intake manifold of the internal combustion engine is used for this purpose. During flushing, the chamber shut-off valve is closed and the flushing valve is opened. Air, supplied by a pump, flows through the hydrocarbon filter and absorbs the fuel or hydrocarbons temporarily stored there, resulting in a fluid downstream of the filter composed of air and fuel or hydrocarbons in any proportion. Downstream of the hydrocarbon filter, with the chamber shut-off valve closed and the flushing valve open, the fluid flows towards the intake manifold of the internal combustion engine and is burned in the engine. Therefore, hydrocarbon filter flushing occurs during the operation of the drive unit or internal combustion engine.

[0012] To reliably prevent fuel, especially gaseous fuel, from escaping into the external environment, it is necessary to perform leak checks at least temporarily, i.e., once or several times, particularly periodically. For fuel tanks designed as pressure tanks, this can be simply done by checking whether overpressure develops in the fuel tank over time when the tank shut-off valve is closed. If the overpressure, i.e., the pressure in the fuel tank relative to the pressure in the external environment, exceeds a certain threshold, then it can be inferred that the fuel tank is sealed. However, if the overpressure, especially within a certain period after the tank shut-off valve is closed, does not exceed the pressure threshold, then—optionally—a leak in the fuel tank is identified. In other words, it is preferable to identify only the sealing and not the non-sealing. This, however, can be done additionally. For example, it can be assumed that if the described method does not infer the sealing of the fuel tank, then the fuel tank is non-sealed.

[0013] Additionally or alternatively, besides the fuel tank, other areas of the fuel tank assembly, particularly the area between the tank shut-off valve, the cut-off valve, and the flush valve in flow technology, are inspected for leak testing. This area specifically includes the hydrocarbon filter and / or the pump. To perform the leak test, the tank shut-off valve is opened, the flush valve is closed, and air is pumped toward the fuel tank. The current intensity used to operate the pump is determined. If the current intensity exceeds a specific current intensity threshold, it can be inferred that the fuel tank assembly is adequately sealed, as the current intensity is directly related to the pressure present in the fuel tank. However, if the current intensity does not reach the current intensity threshold, a leak in the fuel tank assembly is identified.

[0014] However, the described method either only enables leak checks in the fuel tank or is inaccurate when comparing current intensity to a current intensity threshold. For this reason, it is now stipulated that the pressure in the fuel tank be determined first and compared to a pressure threshold. The determination of the pressure in the fuel tank is performed with the tank shut-off valve closed. If the pressure is greater than the pressure threshold, then the first leak check operation is performed.

[0015] In the first leak-check operation mode, the shut-off valve, which is located between the pump and the external environment in the flow technology, is first closed. Then, the tank shut-off valve is opened. This creates pressure compensation in the area between the tank shut-off valve, flushing valve, and shut-off valve in the flow technology of the fuel tank and fuel tank assembly. Specifically, the overpressure present in the fuel tank decreases towards this area. However, because the volume of the fuel tank is significantly larger than the volume of the area far from the fuel tank, only a small pressure decrease occurs in the fuel tank; conversely, the pressure increases significantly in areas different from the fuel tank.

[0016] During the inspection period, the pressure in the fuel tank is now measured using a pressure sensor. Throughout the inspection period, the tank shut-off valve remains open, while the cut-off valve remains closed. If the pressure in the fuel tank drops during the inspection period or a specific timeframe, the pressure difference causing that pressure drop is determined. In this sense, a pressure drop is understood as a decrease in pressure during the inspection period or a specific timeframe that includes at least a portion of the inspection period.

[0017] The pressure difference describes the degree of pressure drop; for example, it corresponds to the difference between a first pressure present at the beginning of a particular period and a second pressure present, specifically at the end of that period. If the pressure difference exceeds a threshold value, it can be assumed that fluid is escaping from or has escaped from the fuel tank assembly toward the external environment. Therefore, a leak in the fuel tank assembly is identified in this case.

[0018] The practices described within the scope of the first leak-checking operation mode enable leak checks on the entire fuel tank assembly, particularly the fuel tank itself and areas distinct from it, and not just the fuel tank. High accuracy in leak checking is achieved because it is performed using pressure sensors, rather than relying on pump current intensity. Therefore, fast and reliable leak checking is generally achieved, relating to overpressure present in the fuel tank. In this respect, the first leak-checking operation mode is essentially based on the fact that the fuel tank is designed as a pressure tank.

[0019] An improved embodiment of the present invention specifies that a second leak detection operation mode is executed when the pressure in the fuel tank is less than or equal to a pressure threshold. In the second leak detection operation mode, the tank shut-off valve is opened, and air is pumped from the external environment toward the fuel tank by a pump until the pressure measured by a pressure sensor reaches the target pressure. After the pressure reaches the target pressure, the shut-off valve is closed. After the shut-off valve is closed, the pressure in the fuel tank is measured by a pressure sensor during the inspection period. When the pressure difference within a specific period exceeds a difference threshold, a leak in the fuel tank device is identified.

[0020] In this regard, if the pressure in the fuel tank is insufficient to perform the first leak check operation, then the second leak check operation is performed. In this case, the second leak check operation is performed instead of the first. The second leak check operation also specifies that the tank shut-off valve is opened and the flushing valve is closed. Subsequently, with the shut-off valve open, air is pumped from the external environment toward the fuel tank using a pump, causing the pressure in the fuel tank assembly to rise. If the pressure measured in the fuel tank reaches the target pressure, then the shut-off valve is closed. Here, the tank shut-off valve remains open, and the flushing valve remains closed. A check period follows, during which the operation proceeds as previously described. Even when the pressure in the fuel tank is too low for the first leak check operation, the described method can still perform leak checks on the fuel tank assembly.

[0021] An improved embodiment of the invention specifies that, in the first leak detection operation mode, after the tank shut-off valve is opened, the pressure in the fuel tank is measured during a monitoring period, and a malfunction of the fuel tank assembly is inferred if there is no pressure decrease. The monitoring period precedes the inspection period. Preferably, the monitoring period follows directly after the opening of the tank shut-off valve, so that the pressure in the fuel tank decreases during the monitoring period. If there is no pressure decrease, then a malfunction of the fuel tank assembly is inferred.

[0022] A fuel tank assembly malfunction can be understood as a failure of either the tank shut-off valve or the pressure sensor. If a previous diagnostic of the pressure sensor has been performed and indicates that it is functioning correctly, then a failure of the tank shut-off valve is directly inferred. Otherwise, a fault suspicion is triggered, including possible failures of both the tank shut-off valve and the pressure sensor. A diagnostic of the pressure sensor is then performed. If a fault suspicion exists and the diagnostic indicates that the pressure sensor is functioning correctly, then a failure of the tank shut-off valve is inferred. Conversely, if a fault in the pressure sensor is identified within the diagnostic scope and a fault suspicion exists, then a failure of the pressure sensor is inferred. In summary, this achieves extremely accurate diagnostics and leak detection.

[0023] An improved embodiment of the invention specifies that, during a monitoring period, the pressure gradient over time is determined and compared with a gradient threshold. The pressure is determined when the gradient is below the gradient threshold, and the operation switches from a first leak check mode to a second leak check mode when the pressure is below a minimum pressure. During the monitoring period, the pressure gradient over time is determined, either in addition to checks for no pressure decrease or as an alternative to checks for no pressure decrease. Here, the pressure gradient is determined by the measured pressure. The gradient is continuously or periodically determined, particularly until the gradient falls below the gradient threshold, i.e., less than the gradient threshold.

[0024] The current pressure is determined when the gradient falls below a gradient threshold. In other words, once the gradient is below the gradient threshold, the current pressure is determined. The pressure is compared to the minimum pressure. If the pressure is below the minimum pressure, it can be inferred that the pressure present in the fuel tank before opening the tank shut-off valve was insufficient to perform the first leak check operation mode. For this reason, the system switches to the second leak check operation mode in this case.

[0025] Switching to the second leak check operation mode means that the shut-off valve is opened and the pump operates to pump air from the external environment toward the fuel tank until the pressure measured in the fuel tank reaches the target pressure. The shut-off valve is closed when the pressure reaches the target pressure or immediately after the pressure reaches the target pressure. Subsequently, the check period begins, during which the method of the above-described implementation scheme is performed.

[0026] An improvement of the invention specifies that the inspection period begins if the pressure is greater than or equal to the minimum pressure. Therefore, if the pressure present when the gradient is below the gradient threshold is at least equal to the minimum pressure, the inspection period begins, preferably immediately, so that the inspection period directly follows the monitoring period. This ensures that the pressure present in the fuel tank assembly is still sufficient to perform leak checks.

[0027] An improvement of the invention specifies that leaks are classified based on the pressure difference over a specific period. Here, for example, multiple leak levels are defined, and each leak level is assigned a pressure difference threshold. After determining the pressure difference, a leak level with the maximum threshold is selected from the leak levels, which is at least reached or exceeded by the pressure difference. Preferably, an equivalent diameter of the leak is assigned to each leak level. For example, a first leak level exists for an equivalent diameter of 0.5 mm, and a second leak level exists for an equivalent diameter of 1.0 mm. The leak levels enable a sufficiently accurate description of the degree of leakage. Preferably, a fault is entered into the vehicle's fault memory according to the selected leak level.

[0028] An improvement of the invention specifies that, in both the first and second leak-check operation modes, a flushing valve located between the hydrocarbon filter and the intake manifold is closed. This prevents fluid from escaping from the fuel tank assembly toward the intake manifold and thereby reduces the need for leak checks.

[0029] An improved embodiment of the invention specifies that the check valve of the pump assembly with the pump is used as a shut-off valve. Therefore, the pump assembly has both a pump and a shut-off valve. The shut-off valve is designed as a check valve, allowing only flow from the external environment into the fuel tank assembly, but not the reverse flow. Therefore, this method can be implemented with minimal overhead. The check valve can, of course, exist as a purely mechanical check valve or an electrically controlled check valve, which can be selectively opened and closed by manipulation.

[0030] An improved embodiment of the invention specifies that, after the inspection period, the tank shut-off valve is closed and the shut-off valve is opened, allowing the fluid, including air and gaseous fuel, existing between the tank shut-off valve and the hydrocarbon filter in the flow process to flow towards the external environment through the hydrocarbon filter. Therefore, after the leak inspection is completed, the fuel tank is separated from other areas of the fuel tank assembly in the flow process by closing the tank shut-off valve. To reduce overpressure in other areas, the shut-off valve is opened. The fluid present there then flows towards the external environment, i.e., through the hydrocarbon filter, causing the fuel contained in the fluid to deposit and be temporarily stored in the hydrocarbon filter. The tank shut-off valve is closed before the shut-off valve is opened. Specifically, the shut-off valve is opened only when the tank shut-off valve is fully closed. This prevents a large amount of fluid from flowing from the fuel tank through the hydrocarbon filter, and thus preventing a large amount of fuel from accumulating in the hydrocarbon filter.

[0031] The present invention also relates to a fuel tank device for a motor vehicle specifically for performing a method according to an embodiment within the scope of the specification, the fuel tank device having a fuel tank, a hydrocarbon filter and a pump, wherein the fuel tank is connected to the hydrocarbon filter via a tank shut-off valve in the flow technique, and the hydrocarbon filter is connected, on the one hand, to the external environment of the fuel tank device via the pump in the flow technique, and on the other hand, to the intake manifold of an internal combustion engine via a flushing valve in the flow technique.

[0032] Here, the fuel tank device is configured and designed to perform a first leak check operation mode when the pressure present in the fuel tank is greater than a pressure threshold. In the first leak check operation mode, the shut-off valve arranged between the pump and the external environment in the flow technology is closed, and the tank shut-off valve is opened. Then, during the check period, the pressure in the fuel tank is measured by means of a pressure sensor arranged in the fuel tank. When the pressure difference of the pressure drop within a specific period exceeds the difference threshold, a leak in the fuel tank device is identified.

[0033] The advantages of this design and practice for the fuel tank device have been pointed out. The fuel tank device and the method for operating it can be improved based on the embodiments described within the scope of this specification, and are therefore referred to accordingly.

[0034] The features and combinations thereof described in the specification, and particularly those described in and / or shown in the accompanying drawings, may be used not only in the separately described combinations, but also in other combinations or individually, without departing from the scope of the invention. Therefore, embodiments not explicitly shown or described in the specification and / or drawings, but which are derived from or can be derived from the described embodiments, should also be considered to be included in the invention. Attached Figure Description

[0035] The invention will now be described in detail with reference to embodiments shown in the accompanying drawings, without limiting the scope of the invention. Hereinafter: Figure 1 A schematic diagram of a fuel tank device for a motor vehicle is shown. Figure 2 A flowchart illustrating a method for operating a fuel tank device is shown. Detailed Implementation

[0036] Figure 1A schematic diagram of a fuel tank assembly 1 is shown, which is preferably a component of a motor vehicle (not shown further herein). The fuel tank assembly 1 includes a fuel tank 2, a hydrocarbon filter 3, and a pump 4. The fuel tank 2 is connected to the hydrocarbon filter 3 via a tank shut-off valve 5 in flow technology. The hydrocarbon filter 3 is further connected, on the one hand, to the external environment 8 of the fuel tank assembly 1 in flow technology via the pump 4, a shut-off valve 6, and an air filter 7, and on the other hand, to the intake manifold 10 of an internal combustion engine 11 in flow technology via a flushing valve 9. The internal combustion engine 11 forms part of the drive unit 12 of the motor vehicle.

[0037] The tank shut-off valve 5, the cut-off valve 6, and the flush valve 9, or their respective control devices, are electrically connected to the controller 13. The same applies to the pump 4 in other respects. Furthermore, a pressure sensor 14, located in the fuel tank 2 and used to measure the pressure present in the fuel tank 2, is connected to the controller 13. A fuel injection line 15 is connected to the fuel tank 2. The fuel injection line 15 has a tank opening 16 on its side facing away from the fuel tank 2, which is closed by means of a tank cover 17.

[0038] Figure 2 A flowchart of a method for operating fuel tank assembly 1 is shown. The method begins at start point 18. Following start point 18 is a delay step 19, which uses this delay step to wait for a determined period. Subsequently, in step 20, it is determined whether only fuel tank 2 or the entire fuel tank assembly 1 should undergo a leak check. If the former, then query 21 to see if the pressure present in fuel tank 2 is greater than a pressure threshold. If this is the case, then the process branches to step 22, in which a first leak check operation mode is initiated. Otherwise, the process branches to step 23, in which a second leak check operation mode is initiated.

[0039] Within the first leak check operation mode, shut-off valve 6 is closed and tank shut-off valve 5 is opened. If a pressure drop in fuel tank 2 is determined within the range of subsequent query 24, then the process branches to query 25; otherwise, it branches to step 26. In step 26, an inspection for defects in tank shut-off valve 5 and pressure sensor 14 begins.

[0040] First, within the scope of query 27, check whether pressure sensor 14 has undergone diagnostics and whether the diagnostics concluded that pressure sensor 14 is operating. If so, then the normal operation of pressure sensor 14 is ensured, and the fault of tank shut-off valve 5 is identified in step 28. Otherwise, branch to step 29, in which the suspected faults of tank shut-off valve 5 and pressure sensor 14 are recorded.

[0041] Subsequently, pressure sensor 14 is diagnosed. If such a diagnosis is performed, the results are checked within the range of query 30. If the diagnosis indicates that pressure sensor 14 is operating normally, then a fault in the tank shut-off valve 5 is identified in step 28. Otherwise, a fault in pressure sensor 14 is identified in step 31.

[0042] Within the range of query 25, the pressure gradient over time is determined during the monitoring period and compared with a gradient threshold. If the pressure gradient is lower than the gradient threshold, the pressure is determined if it is lower than that threshold. If the pressure is less than the minimum pressure, the process branches to step 32; otherwise, it branches to step 33. In step 32, suspicion of a defect or minor leak in shut-off valve 6 is recorded.

[0043] The system then switches to a second leak check operation mode. In this second leak check operation mode, firstly, in step 34, air is pumped from the external environment 8 toward the fuel tank 2 using pump 4. The shut-off valve 6 is opened in advance. During the pumping, the pressure present in the fuel tank 2 is measured using pressure sensor 14. If the pressure reaches the target pressure after a specific period—checked in query 35—then the shut-off valve 6 is closed and the process branches to step 33. Otherwise, in step 36, a malfunction of the shut-off valve 6 or a minor leak in the fuel tank assembly 1 is identified.

[0044] The inspection period begins in step 33. First, delay step 37 is performed. Then, the pressure present in fuel tank 2 is measured and recorded. If a pressure drop occurs, the pressure difference is determined, i.e., in step 38. Subsequently, the inspection period ends in step 39, and the pressure or pressure difference is evaluated in the subsequent step 40.

[0045] In subsequent query 41, the pressure difference is determined. If the pressure difference is less than a first difference threshold, the branch proceeds to step 42. If the pressure difference is at least as large as the first difference threshold, the branch proceeds to step 43. Conversely, if the pressure difference is at least as large as a second difference threshold greater than the first difference threshold, the branch proceeds to step 44.

[0046] Following step 42 is step 45, in which no leak in fuel tank assembly 1 is identified. Following step 43 is step 46, in which a leak in fuel tank assembly 1 with a first leak level is identified. Following step 44 is step 47, in which a leak in fuel tank assembly 1 with a second leak level is determined. The described method ends after each of steps 45, 46, and 47.

[0047] The described method enables highly reliable leak detection of fuel tank assembly 1. Here, it is preferable to always utilize the overpressure present in fuel tank 2 so that pump 4 does not operate in the first leak detection operation mode. Instead, pump 4 is only used during the second leak detection operation mode.

[0048] List of reference numerals in the attached diagram: 1. Fuel tank assembly 2 Fuel Tanks 3. Hydrocarbon filter 4 pumps 5-box shut-off valve 6. Shut-off valve 7. Air Filter 8. External Environment 9. Flushing valve 10. Air intake 11 Internal Combustion Engine 12 Drive unit 13 Controllers 14 Pressure Sensor 15 Fuel Injection Line 16 boxes open 17. Box lid 18 Starting point 19 Delay Steps 20 steps 21 Query 22 steps 23 steps 24 Query 25 Query 26 steps 27 Query 28 steps 29 steps 30 queries 31 steps 32 steps 33 steps 34 steps 35 Query 36 steps 37 Delay Steps 38 steps 39 steps 40 steps 41. Query 42 steps 43 steps 44 steps 45 steps 46 steps 47 steps

Claims

1. A method for a fuel tank device (1) for operating a motor vehicle, wherein, The fuel tank device (1) has a fuel tank (2), a hydrocarbon filter (3), and a pump (4), wherein the fuel tank (2) is connected to the hydrocarbon filter (3) via a tank shut-off valve (5) in the flow technology, and the hydrocarbon filter (3) is connected to the external environment (8) of the fuel tank device (1) via the pump (4) in the flow technology, and is connected to the intake manifold (10) of the internal combustion engine (11) via a flush valve (9) in the flow technology. The device is characterized in that a first leak check operation mode is executed when the pressure present in the fuel tank (2) is greater than a pressure threshold, wherein in the first leak check operation mode, a shut-off valve (6) arranged between the pump (4) and the external environment (8) in the flow technology is closed, and the tank shut-off valve (5) is opened. Subsequently, during the check period, the pressure in the fuel tank (2) is measured by means of a pressure sensor (14) arranged in the fuel tank (2). When the pressure difference of the pressure drop within a specific period exceeds a difference threshold, the fuel tank device (1) is identified as leaking. 1) Leakage; wherein, in the first leak check operation mode, after opening the tank shut-off valve, the pressure in the fuel tank is measured during the monitoring period, wherein the monitoring period is before the check period, and the pressure gradient over time is determined during the monitoring period, and the gradient is compared with the gradient threshold, wherein the pressure is determined when the gradient is lower than the gradient threshold, and the first leak check operation mode is switched to the second leak check operation mode when the pressure is lower than the minimum pressure, wherein, in the second leak check operation mode, the tank shut-off valve (5) is opened, and air is pumped from the external environment (8) toward the fuel tank (2) by means of the pump (4) until the pressure measured by means of the pressure sensor (14) reaches the target pressure, and after the pressure reaches the target pressure, the shut-off valve (6) is closed, wherein, after the shut-off valve (6) is closed, the pressure in the fuel tank (2) is measured by means of the pressure sensor (14) during the check period, and when the pressure difference within a specific period exceeds the difference threshold, a leak in the fuel tank device (1) is identified.

2. The method according to claim 1, characterized in that, The second leak check operation mode is executed when the pressure present in the fuel tank (2) is less than or equal to the pressure threshold.

3. The method according to claim 1 or 2, characterized in that, In the first leak check operation mode, after opening the tank shut-off valve (5), the pressure in the fuel tank (2) is measured during the monitoring period, and a fault in the fuel tank device (1) is inferred if there is no pressure reduction.

4. The method according to claim 1 or 2, characterized in that, If the pressure is greater than or equal to the minimum pressure, the first leak check operation mode check period begins.

5. The method according to claim 1 or 2, characterized in that, Leaks are classified based on the pressure difference caused by the pressure drop over a specific period of time.

6. The method according to claim 1 or 2, characterized in that, In the first leak check operation mode and the second leak check operation mode, the flush valve (9) between the hydrocarbon filter (3) and the intake (10) is closed.

7. The method according to claim 1 or 2, characterized in that, The check valve of the pump assembly with pump (4) is used as a shut-off valve (6).

8. The method according to claim 1 or 2, characterized in that, After the inspection period, the tank shut-off valve (5) is closed and the shut-off valve (6) is opened, so that the fluid, including air and gaseous fuel, between the tank shut-off valve (5) and the hydrocarbon filter (3) in the flow technology flows through the hydrocarbon filter (3) in the direction of the external environment.

9. A fuel tank device (1) for a motor vehicle, specifically designed for performing the method according to any one of the preceding claims, the fuel tank device comprising a fuel tank (2), a hydrocarbon filter (3), and a pump (4), wherein, The fuel tank (2) is connected to a hydrocarbon filter (3) via a tank shut-off valve (5) in the flow technology. The hydrocarbon filter (3) is connected to the external environment (8) of the fuel tank device (1) via a pump (4) in the flow technology, and to the intake manifold (10) of the internal combustion engine (11) via a flushing valve (9) in the flow technology. The fuel tank device (1) is characterized in that it is provided and designed to perform a first leak check operation mode when the pressure present in the fuel tank (2) is greater than a pressure threshold. In the first leak check operation mode, the shut-off valve (6) arranged between the pump (4) and the external environment (8) in the flow technology is closed, and the tank shut-off valve (5) is opened. Subsequently, during the check period, the pressure in the fuel tank (2) is measured by means of a pressure sensor (14) arranged in the fuel tank (2). When the pressure difference of the pressure drop within a specific period exceeds the difference threshold, a leak in the fuel tank device (1) is identified. The fuel tank device (1) is also provided with The device is designed to measure the pressure in the fuel tank during a monitoring period after opening the tank shut-off valve in a first leak check operation mode, wherein the monitoring period is before the check period, and to determine the pressure gradient over time during the monitoring period and compare the gradient with a gradient threshold, wherein the pressure is determined when the gradient is lower than the gradient threshold, and to switch from the first leak check operation mode to the second leak check operation mode when the pressure is lower than the minimum pressure, wherein in the second leak check operation mode, the tank shut-off valve (5) is opened and air is pumped from the external environment (8) toward the fuel tank (2) by means of a pump (4) until the pressure measured by means of a pressure sensor (14) reaches the target pressure, and after the pressure reaches the target pressure, the shut-off valve (6) is closed, wherein after the shut-off valve (6) is closed, the pressure in the fuel tank (2) is measured by means of a pressure sensor (14) during the check period, and a leak in the fuel tank device (1) is identified when the pressure difference within a specific period exceeds a difference threshold.

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