Method for modeling an input current of a pump, and controller

Abstract

The invention relates to a method for modeling an input current of a pump (110). The method comprises the steps of: (i) controlling the pump (110) to pressurize at least a portion of the evaporation system (100), (ii) determining a pressure profile in the evaporation system (100); and (iii) modeling a curve (350) of the input current of the pump (110) on the basis of the pressure curve by means of a model. The invention also relates to a corresponding controller (120).

Description

Technical Field

[0001] This disclosure relates to tank venting systems and methods for operating them. Specifically, this disclosure relates to a method for modeling the input current of a pump and a corresponding controller. Background Technology

[0002] Depending on the specific laws and regulations of each country and for safety reasons, it is necessary to ensure and diagnose the functionality of the fuel tank exhaust system (including the fuel tank) in motor vehicles. Typically, the sealing of the entire evaporation system, from the fuel tank up to the fuel tank exhaust valve, must be checked. Additionally, blockages in the evaporation line between the fuel tank and the activated carbon filter must be checked, or during refueling during the diagnostic process. Depending on the country, different legal requirements exist, such as the minimum leakage cross-section to be diagnosed.

[0003] By using leak diagnostic pumps, various regulatory requirements for evaporation system leak resistance testing are performed on tank systems with or without tank shut-off valves. These leak diagnostic pumps pressurize the evaporation system for a defined period of time. Therefore, the electrical power consumed by the leak diagnostic pump (e.g., based on the pump's current consumption) is then used as an evaluation criterion for determining the leak diameter. The power consumed by such leak diagnostic pumps, or the corresponding pump input current, can also be used for the aforementioned blockage diagnosis and fuel filling detection. Summary of the Invention

[0004] Therefore, the purpose of this disclosure is to enable particularly reliable and accurate modeling of the pump's input current.

[0005] This objective is achieved by a method for modeling the input current of a pump, as claimed in the independent patent claims, and a controller. Advantageous configurations and improvements become apparent from the corresponding dependent claims, the following description, and the accompanying drawings.

[0006] Therefore, a first aspect provides a method for modeling the input current of a pump. The method includes the steps of: (i) controlling the pump to pressurize at least a portion of an evaporation system, (ii) determining a pressure profile in the evaporation system, and (iii) modeling the input current profile of the pump based on the pressure profile using a model.

[0007] On the other hand, a controller for a motor vehicle is provided, wherein the controller is configured to perform the above-described method.

[0008] On the other hand, a computer program product including instructions is provided, which, when executed by a computer, cause the computer to perform the methods described above.

[0009] In the context of this disclosure, an evaporation system can be defined as a system configured to discharge exhaust gases from a storage tank, particularly a fuel storage tank. The evaporation system can be configured to supply exhaust gases to a retention filter, particularly a fuel vapor retention filter, and / or to the air path of an internal combustion engine via at least one purge path. The evaporation system can be an exhaust system, particularly a storage tank exhaust system.

[0010] The evaporation system may have a tank exhaust line. The tank exhaust line may have multiple zones, such as a tank zone, a filter zone, and / or an engine zone. The tank zone may extend between the tank and a tank shut-off valve, or, if no tank shut-off valve is present, between the tank and the filter zone of the tank exhaust line. The filter zone may include a supply line from the tank to a retention filter (particularly the supply line between the tank shut-off valve and the retention filter), an exhaust line between the retention filter and the tank exhaust valve, and / or a fresh air connection to the retention filter. The engine zone may include one or more purge paths between the tank exhaust valve and the air path of the internal combustion engine. The purge paths may lead to air paths downstream or upstream of the throttle valve.

[0011] The evaporation system may have a tank vent valve. This vent valve can be configured to regulate the gas flow rate along the air path from the retention filter to the internal combustion engine. For this purpose, the tank vent valve can be controlled by a controller. The tank vent valve can be positioned between the filter area and the engine area of ​​the tank vent line.

[0012] The evaporation system may have a tank shut-off valve. The tank shut-off valve can be configured to retain exhaust gases (such as hydrocarbon vapors) generated in the fuel tank within the tank, particularly by supplying the exhaust gases to a retention filter in a controlled manner.

[0013] An evaporation system may include a storage tank or at least a portion thereof, particularly the portion from which exhaust gases evaporate from the contents of the storage tank.

[0014] Pressurizing at least a portion of the evaporation system can include pressurizing the entire evaporation system, but specifically excludes the engine area of ​​the tank exhaust line. Such pressurization can include pressurizing at least a portion of the tank, particularly the entire tank. Whether the tank area of ​​the tank exhaust line and / or the tank itself is pressurized may depend on whether the tank shut-off valve is closed.

[0015] The pump can be configured to pressurize at least a portion of the evaporation system, particularly to enable leak testing and / or leak diagnosis of the evaporation system. The pump can be a leak diagnostic pump. In one configuration, the pump is positioned between the retention filter and the fresh air connection.

[0016] Determining a pressure profile may include evaluating signals from pressure sensors. Pressure sensors may be located in at least a portion of the evaporation system pressurized by a pump. For example, pressure sensors may be located in the filter area of ​​a tank vent line. Pressure sensors may be located in the tank vent line between the retention filter and the tank vent valve. Pressure sensors may be located in the tank vent line between the tank vent valve and the tank and / or between the tank vent valve and the tank shut-off valve. Pressure sensors may be located within the tank, for example, on the top side of the tank in contact with the exhaust gas. Determining a pressure profile may include determining a curve representing a variable of pressure.

[0017] Modeling the input current curve of a pump can include modeling the curve of a variable representing the input current (such as electrical power).

[0018] The method described above can facilitate accurate and reliable modeling of the pump's input current. For example, this could be useful for sealing tests, blockage diagnosis, or fuel filling detection in evaporation systems. In particular, discontinuities in the correlation between the pressure curve and the measured input current curve of the pump can be kept harmless. These discontinuities can be caused, for example, by current fluctuations, rather than by pressure changes in the volume to be diagnosed. They might be caused by component tolerances, such as variations in bearing friction, changes in temperature conditions, or fluctuations in the pump's supply voltage. The impact of these discontinuities on the analysis results can be mitigated, in particular, by the fact that the input current curve is not measured but modeled based on the pressure curve.

[0019] Therefore, the described method can help avoid repeated testing of defective components, for example, by avoiding multiple leak tests during the process of shutting down the actuator controller. This allows for reduced energy consumption and / or noise emissions. Furthermore, diagnostic interruptions can be avoided, thus increasing the frequency of successful leak diagnoses. Overall, this can improve the robustness of diagnostic results for monitoring leaks in evaporation systems, for example, by avoiding incorrect good and / or bad tests. This can help suppress current consumption fluctuations, for example, due to insufficient leak diagnostic hardware. In one configuration, fluctuations in the pump's supply voltage can also be compensated for and / or suppressed.

[0020] According to one embodiment, the method further includes: determining whether a leak exists in the evaporation system based on comparing a modeled curve of the input current with at least one reference value.

[0021] In the context of this disclosure, a leak can be defined as a point where exhaust gases from an evaporation system can escape into the environment. A leak can be defined by the minimum cross-section and / or minimum diameter to be diagnosed. The minimum cross-section and / or minimum diameter to be diagnosed can be determined based on legal and / or technical specifications. Determining the presence of a leak in an evaporation system may include determining the leak diameter and / or leak cross-section and / or the total cross-section of all leaks present in the investigated area.

[0022] In the context of this disclosure, a reference value may be a comparative value, such as the value of the pump's input current, which is a characterization of a certain leakage in the evaporation system (especially a leakage with a predetermined cross-section or diameter, such as 0.5 mm).

[0023] In one configuration, at least one reference value is determined by pumping to a reference leak, particularly during reference mode. One or more reference values ​​can be derived by the electrical power consumed by the pump and / or the current consumed by the pump. Multiple reference values ​​can be distributed (particularly continuously distributed) over the time intervals in which the reference leak is pressurized. The reference leak can be part of a tank system, particularly part of the pump.

[0024] In one configuration, at least one new reference value is determined for each sealing test. This allows for compensation for, for example, temperature fluctuations (such as fluctuations in ambient temperature) and / or hardware variations.

[0025] According to one embodiment, modeling the input current curve based on the pressure curve involves multiplying by a scaling factor. For example, the pressure curve and / or the gradient of the pressure curve may be multiplied by a scaling factor. The scaling factor may represent a linear or at least approximately linear relationship between pressure and input current. The scaling factor may at least partially characterize pump characteristics, such as production deviations or special operating conditions for individual pumps.

[0026] This embodiment can be advantageous because the input current associated with leak analysis has a simple relationship with the measured pressure. Therefore, pressure has proven to be a particularly suitable measurement variable for leak testing.

[0027] According to one embodiment, the method further includes determining a scaling factor using a reference mode of the pump, wherein, in the reference mode, the pump pressurizes a reference leak. For example, the scaling factor can be determined based on a reference current consumption. The scaling factor can be determined by measurements of the hardware of a limiting sample and / or a nominal sample. This scaling factor can be determined between a measured inflow current profile of the pump and a pressure profile in the evaporation space. The relationship between the reference current consumption and the scaling factor can be stored in the form of a feature graph.

[0028] In conjunction with this disclosure, the reference mode is understood to specifically refer to the operating mode of the pump where a reference leak is pressurized by the pump. For the sealing test of the evaporation system, the reference mode may be located upstream of the test mode. The reference mode may be performed before each test mode, or only under certain conditions before the test modes.

[0029] The feature map can be determined using extreme sample and / or nominal sample hardware. The scaling factor can be stored in the form of a feature map based on one or more operating conditions (e.g., based on ambient temperature).

[0030] This embodiment may be advantageous for determining the relationship between pressure and current curves with particular precision (especially based on the corresponding operating conditions).

[0031] According to one embodiment, the scaling factor is determined based on at least one of the following parameters: the current intensity of the pump's measured input current before, and particularly immediately before, the switching valve; and the change in the pump's measured input current during and / or after the switching valve, particularly the change in the measured input current caused by the switching valve. The switching valve may indicate the end of the reference mode. The scaling factor may be stored in the form of a feature map based on at least one of the mentioned parameters.

[0032] According to one embodiment, the method further includes adapting the model (specifically the scaling factor) during a test mode of the pump, wherein the pump pressurizes at least a portion of the evaporation system in the test mode. Adapting the model during the test mode may facilitate more accurate and reliable sealing tests of the evaporation system.

[0033] In conjunction with this disclosure, the test mode is understood, in particular, to be an operating mode in which the pump pressurizes at least a portion of the evaporation system. The reference leak may advantageously not be pressurized or may be pressurized only slightly, particularly at a lower pressure than in the reference mode. The test mode can be configured to identify one or more leaks in the evaporation system. The test mode can be downstream of the reference mode. Switching from the reference mode can be achieved by switching the corresponding valve.

[0034] According to one embodiment, the feature map used to determine the scaling factor in reference mode is updated after the scaling factor is adapted and adjusted.

[0035] According to one embodiment, the adaptive adjustment of the model (in particular the scaling factor) includes the following steps: (i) checking whether the operating conditions of the pump meet a predetermined stability criterion between two predetermined times, (ii) determining the difference between the modeling input current and the measured input current of the pump under their respective conditions at the two predetermined times, and (iii) if the stability criterion is met between the two predetermined times, correcting the model, in particular the scaling factor, based on the difference between the two predetermined times.

[0036] Operating conditions can be, for example, the gradient of the measured curve of the pump's supply voltage, battery voltage, the pump's input current, or the gradient of the pressure curve of at least a portion of the evaporation system pressurized by the pump. According to an improvement, corresponding stability criteria are predefined for several (especially all) of these operating conditions. Therefore, the discontinuities already mentioned can be determined with particular reliability.

[0037] This implementation may be advantageous in permanently ensuring the quality of the modeled current profile, for example, by compensating for any variations in hardware characteristics. The difference between the modeled input current swing and the measured input current swing between two times, and / or the difference between the modeled input current and the measured input current between two times, can be characteristics of model bias, particularly the scaling factor.

[0038] According to one configuration, the correction of the scaling factor includes: determining the difference between two differences between the modeling input current and the measured input current at two times, and correlating this difference with the difference between the measured input current at the two times. The result can be a scaling factor deviation, which can be at least partially, and in particular fully, taken into account in further sealing tests.

[0039] According to one embodiment, the operating conditions include at least one of the following parameters: the pump supply voltage, the gradient of the measured curve of the pump input current, and the gradient of the pressure curve. According to one configuration, all these parameters must meet corresponding stability criteria. This embodiment can be advantageous because the stability of at least one parameter, and in particular all of them, can indicate that the model has been appropriately adapted and adjusted.

[0040] According to another embodiment, the method further includes: measuring the curve of the pump's input current.

[0041] According to another embodiment, the method further includes receiving, in particular via a controller, a measurement curve of the pump's input current.

[0042] According to another embodiment, the method further includes: determining an initial value for a modeling curve of the input current, wherein the initial value is based on a current value of a measured curve of the input current at which the gradient of the measured curve exceeds a predetermined threshold. For example, the initial value can be set equal to the current value. The initial value can indicate the time start point of the modeling curve. An additional curve can be determined by a scaling factor. This embodiment can be advantageous because exceeding the threshold can signal the pump to begin pressurizing the evaporation system.

[0043] According to another embodiment, the model properties (particularly the functional correlation between the pressure curve and the modeling current curve and / or initial values) are selected such that if the fluctuations in the measured curves are not caused by pressure changes in the evaporation system, the fluctuations in the measured curve of the input current are more pronounced than the corresponding fluctuations in the modeling curve of the input current. The modeling current will not have corresponding fluctuations. This embodiment can be advantageous because it at least partially detects and accounts for the discontinuity between the measured current curve and the pressure curve during the sealing test.

[0044] According to another embodiment, the method further includes performing fault diagnosis on the evaporation system, wherein the fault diagnosis takes into account a modeling curve of the pump's input current. For example, a sealing test, a blockage test, and / or a fuel filling detection may be performed.

[0045] According to another embodiment, the fault diagnosis considers the modeling curve of the input current when at least one of the following conditions is met: (i) the gradient change of the measured curve of the input current exceeds a predetermined discontinuity threshold; (ii) the absolute value of the gradient of the measured curve of the input current exceeds another predetermined discontinuity threshold; (iii) the fluctuation of the pump supply voltage exceeds a predetermined voltage threshold.

[0046] According to one configuration, fault diagnosis considers the modeling curve of the input current only if at least one of the conditions is met. Otherwise, when none of the conditions are met, fault diagnosis can be performed based on a comparison of the measured curve of the input current with at least one reference value.

[0047] This embodiment can be advantageous when there is no discontinuity in the ratio of the current curve to the pressure curve, by using the measured current to perform a sealing test, thus saving storage and computational resources when modeling the current curve.

[0048] According to one embodiment, the discontinuity threshold and / or another discontinuity threshold depend on the pressurized volume. This embodiment can detect and classify discontinuities related to the sealing test in the ratio of the measured current curve to the pressure curve in a particularly reliable manner.

[0049] In a favorable improvement, the discontinuity threshold and / or another discontinuity threshold are stored in the form of a feature map, for example, based on the current tank filling level and the volume to be diagnosed.

[0050] According to one embodiment, in each sealing test, the presence of a leak in the evaporation system is determined based on a comparison of a modeled curve of the input current with at least one reference value. This approach can be advantageous because it eliminates the potentially complex condition interrogation described above.

[0051] According to one embodiment, if a leak is present, the size of the leak is determined. The leak size can be determined by comparing a modeled current curve with at least one reference value. The leak size can be determined by the cross-sectional area and / or diameter (e.g., average diameter) of the leak. In one configuration, only the region is determined, such as whether the leak has a diameter between 0.5 mm and 1.0 mm (including end values), or whether the leak has a diameter greater than or equal to 1.0 mm.

[0052] According to one embodiment, a method is provided for detecting blockages in an evaporation system based on a pressure profile and / or a modeling profile of the input current. In addition to the steps of the method described above, the method further includes the following steps: (i) determining a measurement current gradient, a measurement pressure gradient in the tank, and a measurement pressure gradient in the purge line during a test mode; (ii) detecting a blocked line when: (a) the measurement current gradient is greater than an adjustable threshold; (b) the measurement pressure gradient in the tank and / or the gradient of the modeling current profile are less than the corresponding adjustable threshold; and (c) the measurement pressure gradient in the purge line is greater than an adjustable threshold. Specifically, the described method can be used to detect blockages between a fuel tank and a retention filter.

[0053] Alternatively, instead of the corresponding gradient, the absolute value can be evaluated at (i) and (ii) after a predetermined time interval (particularly an adjustable predetermined time interval). In another embodiment, using a measured pressure gradient in a purge line or in a storage tank can also be considered optional.

[0054] According to one embodiment, a method is provided for detecting refueling based on pressure profiles and / or modeling profiles of input current, and in addition to the steps of the method described above, the method further includes the steps of: (i) determining changes in the measured current gradient, changes in the measured pressure gradient in the tank, and changes in the measured pressure gradient in the purge line during a test mode; (ii) detecting a refueling operation when: (a) the change in the measured current gradient is greater than an adjustable threshold; (b) the change in the measured pressure gradient in the tank and / or the gradient change in the modeling current profile is greater than a corresponding adjustable threshold; and (c) the change in the measured pressure gradient in the purge line is greater than an adjustable threshold. Specifically, refueling can be detected during a sealing test.

[0055] Alternatively, the absolute values ​​of the gradients can be evaluated at points (i) and (ii) during the test mode. Fueling can be terminated if both the measured current gradient and the measured pressure gradient reach adjustable thresholds within the test mode. In another embodiment, using the measured pressure gradient change in the purge line can also be considered optional. Attached Figure Description

[0056] Further advantages, advantageous configurations, and improvements of the method and controller become apparent from the following exemplary embodiments illustrated in conjunction with the accompanying drawings. In the attached diagram: Figure 1 An evaporation system is shown, which includes control means for performing a sealing test method according to a first exemplary embodiment of the present disclosure; Figure 2 A flowchart illustrating different variations of the selection method to incorporate modeled current consumption into fault diagnosis of an evaporation system, according to a first exemplary embodiment of this disclosure, is shown. Figure 3 The modeling curves of the pump's input current during reference mode and test mode are shown in the method of a first exemplary embodiment according to this disclosure; Figure 4 and Figure 5 Each example illustrates a comparison between a modeling curve of the input current and a measured curve of the input current in a method according to a first exemplary embodiment of this disclosure; Figure 6 and Figure 7 The method of a first exemplary embodiment of this disclosure illustrates the characteristic variable of the current consumption of a leak diagnostic pump when the scaling factor between the pressure curve of the input current and the modeling curve is adaptively adjusted.

[0057] Throughout the accompanying drawings, identical or similar elements, or elements that function in the same manner, are given the same reference numerals. In some drawings, individual reference numerals have been omitted for clarity. The figures shown in the drawings and the scale of the elements relative to each other should not be considered to be drawn to true scale. Rather, for better illustrativeness and / or better understanding, the elements may be shown at enlarged dimensions. Detailed Implementation

[0058] Figure 1 An evaporation system 100 is shown, including a controller 120 configured to perform a sealing test method according to a first exemplary embodiment. Figure 1 The evaporation system 100 shown is equipped with a leak diagnostic pump 110 at the fresh air inlet of the fuel vapor retention filter 109 (in this case, an activated carbon filter). Hydrocarbons released from the storage tank 130 are trapped in the activated carbon filter 109.

[0059] The evaporation system has a tank vent valve 106, which can be in the form of a switching valve or a linear valve. A controller 120 (here, an engine controller) controls the tank vent valve 106 to regulate the gas flow from the activated carbon filter 109 to the air path 140 of the internal combustion engine. Typically, for pressure tank variants, but not for conventional tank variants, the tank system also has a tank shut-off valve 107. The tank shut-off valve 107 can be used to retain hydrocarbon vapors generated in the fuel tank in tank 130 so that they can be subsequently supplied to the activated carbon filter 109 in a controlled manner under suitable operating conditions.

[0060] In addition, the tank system includes: (i) an exhaust line (tank area) 102 between the fuel tank 130 and the tank shut-off valve 112; (ii) a tank exhaust line (filter area) 101 for guiding hydrocarbon gas from the fuel tank 130 to the activated carbon filter 109 and further to the tank exhaust valve 106; and (iii) a tank exhaust line (engine area) 103 for introducing hydrocarbon gas downstream of the tank exhaust valve 106 from the activated carbon filter 109 into the air path 140 of the internal combustion engine. A pressure sensor 111 is arranged in the tank exhaust line (filter area) 101 between the activated carbon filter 109 and the tank exhaust valve 106. An additional pressure sensor 111 and an optional temperature sensor, or a combination of pressure / temperature sensors, are arranged in the fuel tank 130.

[0061] The electronic controller 120 is configured to perform a method for modeling the input current of the pump 110. The method includes the steps of: pressurizing at least a portion of the evaporation system 100 by means of the pump 110; determining a pressure profile in the evaporation system 100; and modeling a profile of the input current of the pump 110 based on the pressure profile using a model.

[0062] The controller 120 may also be configured to perform at least one, and in particular all, of the following steps or methods: (a) determining a target value for the purge flow rate from the activated carbon filter 109 to the internal combustion engine under current operating conditions; (b) determining the intake manifold pressure using a pressure sensor in the intake duct; (c) reading the value from the pressure sensor; (d) determining a PWM (Pulse Width Modulation) value for controlling the reservoir exhaust valve 106 based on the pressure gradient from the predetermined purge flow rate between the fresh air connection of the activated carbon filter 109 and the inlet point in the air path 140 of the internal combustion engine; (e) calculating the amount of fuel to be injected under the current operating conditions of the engine; (f) controlling the leak diagnostic pump 110 and measuring current consumption; and (g) controlling the reservoir shut-off valve 107 (if present).

[0063] Figure 2 A flowchart is shown in a diagnostic method (e.g., tank sealing test method, blockage test and / or refueling detection) for incorporating modeled current consumption of a leak diagnostic pump into an evaporation system. To address the discontinuity in the correlation between pressure curves and the current consumption of pump 110 in terms of diagnostic result quality, a relevant current curve is calculated based on the measured gas pressure curve. The pressure curve is measured and evaluated in either the tank area or the filter area, depending on whether the aim is to diagnose the tank area including the filter area using tank pressure sensor 111, or to diagnose only the filter area using pressure sensor 111 in the filter area. According to a first variant of the method, the incorporation of the current curve, corrected using the measured gas pressure curve, can be performed sequentially to form a diagnostic result (step S1).

[0064] In another variation of this method (asked in step S2), a current curve corrected using a measured gas pressure curve is incorporated only if current fluctuations (or continuous current gradients) are detected, and these fluctuations cannot be caused by the gas pressure curve in the volume to be diagnosed. To detect current fluctuations, the current curve is measured, and the gradient change of the measured current curve is compared to an adjustable threshold. This threshold is stored in the controller as a characteristic map value based on the current tank fill level and the volume to be diagnosed (tank and filter area, or filter area only). To detect high absolute values ​​of current gradients, the absolute value of the gradient of the measured current curve is compared to an adjustable threshold. This threshold is also stored in the controller as a characteristic map value based on the current tank fill level and the volume to be diagnosed (tank and filter area, or filter area only).

[0065] A method for determining whether to perform a sealing test using a modeled current curve or a measured current curve of the pump's input current comprises the following steps: In a first step S1, the sealing test is asked whether it is always based on the modeled current curve rather than the measured current curve. If no (n), in a second step S2, the method asks whether current fluctuations or high absolute values ​​of the measured current gradient have been detected. If no (n), in a third step S3, the method asks whether battery fluctuations have been detected. If this question is also answered no (n), the sealing test is performed based on the measured current curve in a further step S4. However, if only one of the questions S1, S2, and S3 is answered yes (y), the sealing test is performed based on the modeled current curve in step S5.

[0066] Figure 3 The curves of the input current 350 versus time 352 during different diagnostic phases 353 and 354 of the method according to the first exemplary embodiment are shown. Specifically, the curves of the pump's input current during reference mode 353 and test mode 354 are shown. In order to calculate the current curve corrected or modeled using pressure curves, it is first necessary to determine the scaling factor between pressure and current, where the scaling factor characterizes the characteristics of the underlying pump hardware. This characteristic determination is intended to be performed within the first diagnostic phase (reference mode 353). In reference mode 353, a reference current consumption for the measured input current of the pump is determined, wherein the scaling factor is determined by the established reference current consumption level and / or the change in the measured pump current consumption when switching the valve of the leak diagnostic pump. The quantitative relationship is stored here in the feature map and was previously determined by measuring the hardware of the limiting sample and / or nominal sample.

[0067] exist Figure 3The noticeable reduction in current consumption is caused by the activation of the switching valve and marks the transition between reference mode 353 and test mode 354. The switching valve switches from reference mode 353, which pressurizes a reference leak, to test mode 354, which pressurizes at least a portion of the evaporation system.

[0068] After the scaling factor has been determined, additional steps are performed, which are intended to be explained using the following figures.

[0069] Figure 4 An initial value 456 for determining the modeling curve 350 of the pump's input current is shown in the method according to the first exemplary embodiment. After the switching valve switches from reference mode 353 to test mode 354, the current curve 455 of the pump's input current is measured and filtered, and then the gradient is determined. If the gradient of the determined filtered measured current curve 455 is greater than an adjustable threshold, an initial value 456 is formed for subsequent calculation of the modeling current curve 350. The initial value 456 is equal to the filtered measured current value at the time described.

[0070] To form the modeling current curve 350, the measured pressure in the evaporation space is first filtered, for example, using a low-pass filter. The gradient of the filtered measured pressure in the evaporation space is then calculated at equal time intervals (e.g., 1 s). This gradient of the filtered measured pressure in the evaporation space is then multiplied by a previously determined scaling factor at the same equal time intervals. The final filtering of this product defines the modeling current curve 350.

[0071] Figure 5 The method according to the first exemplary embodiment is illustrated with a measured current curve 455 and an associated modeled current curve 350, wherein current fluctuations caused by defects in the pump hardware can be seen at discontinuities 557 in the measured current curve 455. On the other hand, the modeled current curve 350 eliminates such current fluctuations that are detrimental to the leak diagnosis and assessment algorithm.

[0072] Figure 6 and Figure 7The illustration shows characteristic variables of the input current measurement curve 455 and the modeling curve 350 when the scaling factor between the measurement curve 455 and the pressure curve is adaptively adjusted in the method according to the first exemplary embodiment. To permanently ensure the quality of the modeling current curve 350, the scaling factor must be adaptively adjusted to compensate for any changes in hardware characteristics. This adaptive adjustment is achieved using four physical variables continuously determined during diagnostics in test mode: 1) the integral 661 of the measured current gradient; 2) the integral 662 of the modeling current gradient; 3) the difference 663 between the integral of the measured current gradient and the integral of the modeling current gradient at a first time point 664 and a second time point 665; and 4) the filtered measured pump-inflow current 455.

[0073] For example, the following steps can be performed to determine the error in the current curve modeling process: (i) determining the stability of the battery voltage (especially the pump supply voltage); (ii) determining the stability of the measured current gradient and the measured gas pressure gradient, for example by continuously comparing weakly attenuated or filtered measured current or pressure gradients with strongly attenuated or filtered measured current or pressure gradients; (iii) determining whether conditions (i) and (ii) have existed for at least a certain settable time; (iv) after conditions (i) and (ii) have existed for at least that settable time, the initial value of the difference between the integral of the measured current gradient and the integral of the modeled current gradient is equal to the integral of the measured current gradient and the modeled current gradient at that first time point 664. (v) The current dominant difference between the integrals of the current gradient, and the initial value of the measured pump inflow current at the same time 664 is equal to the current dominant value; (vi) The stored initial value is retained as long as stability criteria (i) and (ii) are satisfied; (vi) If stability criteria (i) and (ii) are no longer satisfied, the final value is formed at time 665 by equalizing the final value of the physical variable mentioned in (iv) to the current dominant value, while still retaining the initial value of step (iv); (vii) If the stability criteria at points (i) and (ii) satisfy the settable minimum time, the error is determined, for example, according to the following formula, which is expressed as a percentage of the applied scaling factor: 100% [(The difference between the integral of the measured current gradient at the second time 665 and the integral of the modeled current gradient 663) - (The difference between the integral of the measured current gradient at the first time 664 and the integral of the modeled current gradient 663)] / [(The filtered measured pump inflow current at the second time 665) - (The filtered measured pump inflow current at the first time 664)].

[0074] The determined error can then be used proportionally or 100% in the next modeling cycle to accommodate the adjustment of the scaling factor.

[0075] This invention is not limited to the exemplary embodiments described herein. Rather, this invention includes any novel features and any combination of features, particularly any combination of features in the exemplary embodiments and the patent claims.

[0076] Figure Labels 100 Evaporation System 101 Storage Tank Vent Pipeline (Filter Area) 102. Tank venting pipeline (tank area) 103 Storage tank exhaust line (engine area) 104 First Purging Path 105 Second purge path 106 Storage Tank Vent Valve 107 Storage Tank Shut-off Valve 108 Check Valve 109 Fuel vapor retention filter 110 Leak Diagnostic Pump 111 Pressure Sensor 112 Flow direction 120 controller 121 signal line 130 fuel storage tank 140 Air path of internal combustion engine 141 Air Filter 142 Throttling valve 350 Modeling Current Curve 351 Current Intensity 352 Time 353 Reference Mode 354 Test Mode 455 Measurement of current curve 456 Initial value 557 Discontinuities 661 Integral measurement of current gradient 662 Modeling the integral of the current gradient 663 The difference between the integral of the measured current gradient and the integral of the modeled current gradient. 664 First Moment 665 Second moment.

Claims

1. A method for modeling an input current of a pump (110), the method comprising the steps of: - controlling the pump (110) to pressurize at least a portion of an evaporation system (100); - determining a pressure curve in the evaporation system (100); and - modeling a curve (350) of the input current of the pump (110) based on the pressure curve by means of a model.

2. The method of the preceding claim, wherein, Modeling the curve (350) of the input current based on the pressure curve comprises multiplying by a scaling factor.

3. The method according to the preceding claim, further comprising: determining the scaling factor by means of a reference mode (353) of the pump (110), wherein, in the reference mode (353), the pump (110) pressurizes a reference leak.

4. The method of the preceding claim, wherein, The scaling factor is determined based on at least one of the following parameters: a current intensity of a measured input current of the pump (110) before switching a valve of the pump (110), and a change of the measured input current of the pump (110) during and / or after switching the valve of the pump (110).

5. The method according to one of the preceding claims, further comprising: adapting the model during a test mode (354) of the pump (110), wherein, in the test mode (354), the pump (110) pressurizes at least a portion of the evaporation system (100).

6. The method of the preceding claim, wherein, Adapting the model comprises: checking whether an operating condition of the pump (110) fulfills a predetermined stability criterion between two predetermined time instants; determining a difference between a modeled input current (350) and a measured input current (455) of the pump (110) at the two predetermined time instants (664, 665), respectively, in each case; and correcting the model based on the difference at the two predetermined time instants (664, 665) if the stability criterion is fulfilled between the two predetermined time instants (664, 665).

7. The method of the preceding claim, wherein, The operating condition comprises at least one of the following parameters: a supply voltage of the pump (110), a gradient of the measured curve (455) of the input current of the pump (110), and a gradient of the pressure curve.

8. The method according to one of the preceding claims, further comprising: receiving a measured curve (455) of the input current of the pump (110).

9. The method according to the preceding claim, further comprising: determining an initial value (456) of the modeled curve (350) of the input current, wherein the initial value (456) is based on a current value of the measured curve (455) of the input current at which a gradient of the measured curve (455) of the input current exceeds a predetermined threshold value.

10. The method of claim 8 or 9, wherein, A model property of the model is chosen such that fluctuations in the measured curve (455) of the input current are more pronounced than corresponding fluctuations in the modeled curve (350) of the input current if the fluctuations in the measured curve (455) are not caused by a pressure change in the evaporation system (100).

11. The method of one of the preceding claims, further comprising: performing a fault diagnosis of the evaporation system, wherein the fault diagnosis takes into account the modeled curve (350) of the input current of the pump (110).

12. The method of the preceding claim, wherein, The fault diagnosis considers a modeled curve of the input current when at least one of the following conditions is fulfilled: (i) a gradient change of the measured curve (350) of the input current exceeds a predetermined discontinuity threshold; (ii) an absolute value of the gradient of the measured curve (350) of the input current exceeds a predetermined further discontinuity threshold; (iii) a fluctuation of the supply voltage of the pump (110) exceeds a predetermined voltage threshold.

13. The method of the preceding claim, wherein, The discontinuity threshold and / or the further discontinuity threshold depend on the volume being pressurized.

14. A controller (120) for a motor vehicle, the controller being configured to perform the method of one of claims 1 to 13.

15. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of one of the preceding claims 1 to 13.

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