EP1288483A2 - Method and apparatus for emission monitoring of a storage container for storing a volatile medium, in particular of a fuel reservoir of a vehicle - Google Patents

Abstract

The method enables operation of a fluid container whilst monitoring emissions and checking that the container is sealed. The temperature of the fluid relative to e.g. ambient temperature, is determined using calculation models, either continuously or cyclically. The measured value is then either used as a correction value when checking the sealing of the container or, alternatively, the seal check is only carried out when the determined temperature is within predetermined temperature values. Independent claims also cover a circuit for carrying out the method.

Description

BACKGROUND OF THE INVENTION

The invention relates to the monitoring of the emission of Storage containers for storing volatile media, in particular of fuel tank systems used in motor vehicles. The invention relates in particular to a method, a circuit and a control unit for the emission monitoring operation of such Storage container according to the generic terms of respective independent claims.

Have in the most diverse areas of technology Storage containers of the type mentioned in their Tightness to be checked. For example, it is in chemical engineering for emission protection reasons of importance, the tightness of Tanks to store volatile chemicals check. Especially in the field of automotive engineering there is a need to put in there Fuel tanks or tank systems carry out regular leak tests perform.

In the latter context, reference is made to parts of the USA applicable legal regulations for operation pointed out by internal combustion engines. After that it is necessary that motor vehicles where volatile Fuels such as gasoline are used to set up a facility to monitor the emission of fuel, which is able to detect a leak or Leakage of size 0.5 mm in the tank system only with To be able to find on-board means.

So there is a procedure for testing the tightness of one Motor vehicle tank system from US Pat. No. 6,234,152 (DE 198 36 967 A1). This is in the tank system an overpressure compared to the ambient pressure is introduced and from the subsequent pressure history for the existence a leak is closed. Similar procedures to check a tank ventilation system Motor vehicle also go out of the US patents 5,890,474 (DE 196 36 431 A1) and 6,131,550 (DE 198 09 384 A1).

SUMMARY OF THE INVENTION

With the mentioned emission monitoring, in particular the detection of small leaks of the specified cross-sectional size of 0.5 mm, the present invention based on the knowledge that the temperature of the volatile medium have a significant impact on the Measuring accuracy in a leak test (leak diagnosis) Has. On the one hand, the functional tests mentioned, especially with tank systems, only inside certain temperature ranges are carried out because with increasing fuel temperature the outgassing of the medium increases, from a certain temperature an excess pressure in the storage container due to the outgassing arises and this overpressure finally that at Leak test increased pressure or the counteracts generated negative pressure. That way make false assumptions about the pressure conditions are a cause of misdiagnosis In case of a diagnosis carried out with overpressure leaky storage container defective as "tight" and in the case of a diagnosis carried out with negative pressure sealed container is incorrectly diagnosed as "leaking".

Furthermore, in particular in those made of plastic Containers the thermal expansion of the material consider. Because of the rising temperature expansion behavior of the plastic occurs uncontrollable changes in volume of the interior of the container and this in turn leads to false assumptions with regard to the existing internal pressure conditions.

It should also be noted that the term "storage container" for example in the case of motor vehicle tank systems important for the tightness of the entire tank system Functional elements such as lines and seals with includes.

The present invention is therefore based on the object a method, a circuit and a control device of the type mentioned at the beginning, which one improved emission monitoring compared to the prior art allow for said storage containers. In particular, this improvement is intended to be achieved through detection the current temperature of the stored medium with the least possible technical effort, in particular avoiding the use of more expensive Temperature sensors in the storage container are made to hence the accuracy of one on the storage container carried out leak test.

This task is solved by the characteristics of the independent Expectations. Advantageous configurations or Further training is the subject of the subclaims.

The invention is based on the idea of temperature of the volatile medium in one described at the beginning Include functional testing as a correction variable and this based on further parameters, such as the ambient temperature, the fill level of the storage container or, in the case of a motor vehicle, additionally based on operating data of the vehicle (vehicle speed or the like) or the vehicle engine (operating time, Model engine shutdown time, engine temperature or the like), i.e. determined using a model calculation.

According to a first variant, the invention provides the real temperature of the medium (T_ktm) from these Determine parameters arithmetically and the calculated in this way Value of T_ktm, as mentioned above, as a correction quantity when checking the functionality of the storage container included. In a second variant is a test for the functionality of the storage container only carried out if the calculated value of T_ktm within a predeterminable Temperature interval.

The correction size can be in each case in the variants mentioned before performing a function test or temporarily, for example cyclically recurring, by means of the Model calculation can be determined. Alternatively, the parameters required for the calculation of T_ktm according, in particular for a given type of construction of the storage container or a motor vehicle once performed model calculation in the form of a characteristic diagram or saved in a corresponding table and thus stand for the following provisions from T_ktm immediately available without the named Model calculations are carried out again each time got to.

To further refine the proposed method can also include parameters such as the operating or storage period of one due to the storage container supplied internal combustion engine (motor) as well, in the case of a vehicle, the vehicle speed, the fuel level depending on the vehicle speed, and / or the altitude of the storage container or such a container having the vehicle. So when falling Ambient temperature with relative at the same time high geographical height of the vehicle location, e.g. during a mountain pass, due to the lower Air pressure from a reduced cooling rate be assumed. In addition, the respective Vehicle data related characteristics such as Body shape and / or engine type are included, whereby advantageous both different flow conditions when the vehicle is moving and a related one different underflow of a fuel tank as well as different installation positions of the Fuel tanks and / or the engine in the vehicle chassis, depending on the body shape can be. Even if a storage period is included of the engine provided in the model calculation be to store a series-specific cooling curve and this as an initial value when the engine is restarted to be used for the engine temperature.

It should be noted that the model calculation heating curve and / or cooling curve to be taken into account of the medium in the storage container, both in a motor vehicle than when the Storage container, the existing level and the respective series of the container. Thus, a relatively high level due to the result higher heat capacity of the medium slower heating of the stored medium and a relatively low level for faster heating. These relationships are found in the model calculation mentioned according to further design consideration.

Since the prevailing ambient temperature also Heating curve and the cooling curve of the medium are decisive influenced, the ambient temperature at the Determination of T_ktm, for example, taken into account multiplicatively become. In the case of one arranged in a motor vehicle Fuel tank can be used for heating and / or Cooling curve of vehicle and / or engine operating variables such as the current or average Engine load, vehicle speed, and / or gear selection be taken into account or as a correction variable (s) received.

In a further embodiment, T_ktm only becomes one or several parameters determined if the named Parameter (s) within a specifiable range of variance lie, i.e. if the respective parameter Sufficiently constant over a predefinable time interval behaves. Alternatively or additionally, provision can be made be that a redefinition of T_ktm only then occurs when the vehicle speed and / or the Operating time of the engine a predefinable limit exceed. This ensures that the influence of fluctuations due to the situation or the environment of the recorded parameters on the calculated ones Value of T_ktm is minimized. This can ensure be that the engine's operating temperature has reached and no subsequent heating of the engine leads to a further increase in T_ktm. The Waiting time can be, depending on the situation, similar to the one mentioned above the type of engine and / or body shape of the vehicle, for example for individual vehicle series be separated.

Can further increase the functional test reliability be provided that one in operation with the storage container connected motor or one such T_ktm determined vehicle container cached and during subsequent commissioning the engine or the vehicle with a current measured ambient temperature is compared. Until the subsequent redefinition of T_ktm, the larger of the two values as the initial value for T_ktm used. Through this maximum selection advantageously an external heating of the stocked Medium during a parking time of the vehicle, e.g. due to a chassis effect caused by solar radiation and / or tank heating. Similar can also influence the current geographic Take the height position of the vehicle into account.

According to a further embodiment, T_ktm is also used for moving vehicle determines the influence of the engine running near the tank Heat build-up to take into account the fuel temperature.

In addition, the heat input from an existing one electric fuel pump, an engine exhaust system (Exhaust system), and / or the vehicle interior cooling air conditioner or the like, taking into account Find.

Since T_ktm is also with a Medium deviating temperature are changed According to a further embodiment, changes in the tank level for example in a manner known per se. Refueling detected by a fuel cap sensor. As mentioned above, setting can also be done here a temperature equilibrium can be waited until T_ktm is redetermined. Until redefinition can be an approximate value, for example the mean from the last saved value of T_ktm and the current ambient temperature, which has the advantage that at least until then a meaningful one Value is present. Furthermore, a occurring during an interruption of the vehicle Refueling can be recognized by that the start of the engine the difference between the current Tank level and the temporarily stored tank level value exceeds a predefinable threshold value. It It is worth noting that the amount of fuel topped up Medium when recalculating T_ktm after a Include the refueling process in the model calculation can.

As a result, the invention enables it to be used more cost-effectively Plastic tanks, for example in internal combustion engines Motor vehicles without for leak diagnosis of the Size 0.5 mm required to be arranged in the storage container costly temperature sensors. With with "flexible fuel", i.e. in hybrid operation ethanol / methanol operated motor vehicles enables the invention also the detection of critical outgassing temperatures.

In addition, one or more failures Sensors (temperature, tank level sensor, etc.) the determination from the available data a meaningful T_ktm enables. Becomes For example, the failure of a temperature sensor in a manner known per se recognized, the associated temperature variable empirically in the model equation determining substitute value can be assigned, for example average value of 20 ° C. Correspondingly, if there is a defect Tank level sensor, instead of a currently determined T_ktm value, a last saved value of T_ktm can be used.

By falsified T_ktm values for the sensor failures mentioned to suppress more effectively or such adulteration with rapidly changing environmental conditions Avoiding itself can also be a plausibility check be carried out with a current determined T_ktm with predeterminable upper and / or compared lower limits and only then as correct is assumed if T_ktm is within these limits lies. In addition, if a limit value is exceeded the current value is equal to the limit value itself become.

The invention can be advantageous in an existing Control unit, for example an engine control unit, in the form of a control program. This benefits that some or all of the characteristics mentioned are already detected in such a control device. Alternatively, the invention can be in the form of its own Circuit, for example as an Application Specific Integrated Circuit (ASIC) can be realized. The underlying Model calculation in the form of one of several Binary logic circuit formed stages be realized, with each stage as a filter for the Influence of the respective parameter on T_ktm considered becomes. Depending on the parameters and those of the environment dependent correction quantities varies Attenuation of the respective filter. Preferably be based on at least two filters in the model calculation. So the ambient air temperature can be in a first filter as well as the altitude of the vehicle and in the at least second filter the tank level, the vehicle and / or engine shutdown time and the operating time.

In one embodiment, this includes the invention Control unit or the circuit one to the above Read / write memory (RAM) to save the characteristic diagrams mentioned and / or for the intermediate storage of an already determined one T_ktm value.

It should be noted that the invention is basically Storage containers in all areas of technology, in where volatile substances are stored in such a container become applicable. It also goes without saying that the term "storage container" also applies to entire tank systems or the like, including their other components, with includes.

It should also be noted that the one determined according to the invention Value for T_ktm also as a correction variable for functions similar to the function test mentioned, For example for a tank ventilation function mentioned at the beginning, can be used.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

den prinzipiellen Ablauf einer Tankleckdiagnose unter Anwendung des erfindungsgemäßen Verfahrens;

Fig. 2a-d

ein Flußdiagramm eines von der Erfindung Gebrauch machenden Verfahrens zur Bestimmung der Kraftstofftemperatur aus der Außenlufttemperatur;

Fig. 3

ein Flußdiagramm eines Verfahrens zur Überprüfung einer Höhenlageänderung in welcher ein Temperatur-Offset gesetzt wird;

Fig. 4

ein Flußdiagramm eines Verfahrens zur Durchführung einer Minimal-/Maximalbegrenzung der bestimmten Kraftstofftemperatur; und

Fig. 5

ein Ausführungsbeispiel eines Kenngrößendiagramms zur Bestimmung der Kraftstofftemperatur aus den über die Größe Zeit parametrisierten Kenngrößen Außenlufttemperatur und Tankfüllstand.

The invention is explained in more detail below, using the drawings, using preferred exemplary embodiments. Show here

Fig. 1

the basic sequence of a tank leak diagnosis using the method according to the invention;

2a-d

a flow chart of a method making use of the invention for determining the fuel temperature from the outside air temperature;

Fig. 3

a flowchart of a method for checking an altitude change in which a temperature offset is set;

Fig. 4

a flow chart of a method for performing a minimum / maximum limitation of the determined fuel temperature; and

Fig. 5

an embodiment of a characteristic diagram for determining the fuel temperature from the parameters parameterized via the variable time outside air temperature and tank level.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 shows the basic sequence of one of the Invention leak diagnosis routine. To the start 10 of the routine and assuming already in a control unit - usually in a motor vehicle an engine control unit - available parameters these parameters are read from the control unit 15 and based on one below characteristic diagram described in detail below Temperature of the stored medium T_ktm determines 20. This value T_ktm becomes a rewritable Memory, for example a read-only memory (RAM), temporarily stored 25. The query is then carried out in a loop 30 whether a request to perform a leak diagnosis is present. If not, it will be over a delay stage 35 to the beginning of the subroutine jumped back to determine T_ktm. Otherwise a plausibility check is carried out 40 whether the cached value of T_ktm within a given Limits (T_min, T_max). T_ktm is outside these temperature limits, in the embodiment T_ktm equated to the maximum value T_max as a security measure to the 'worst case' value correspond.

In a subsequent step 50, a leak diagnosis process is carried out started, the value of T_ktm again from the RAM read out and, if a result of the Leakage diagnosis, using this result T_ktm corrected. This can be used for leak diagnosis determined leak rate based on an increased material outgassing factor due to the wall material of the Storage container or based on the total used Seals with an appropriate offset value Getting corrected. It can also be used for leak diagnosis assumed negative or positive pressure reduction gradient be corrected accordingly.

A method of determining fuel temperature is described below using the example of a motor vehicle, although that from the description below principles that become clear to others Storage containers such as chemical fabric tanks or the like can be used accordingly. That in the related Figures 2a - 2d illustrated method can, for example, as a control program in an engine control unit or implemented as a separate circuit (ASIC or the like) become. The following process steps, including the filters described below etc., implemented in binary logic known per se become.

According to FIG. 2a, the method begins with one step 100 in which an engine (not shown) started becomes. In a step 110 it is checked whether an engine shutdown time t_maz longer than a given time was. If this is the case, it is assumed that the Fuel temperature after passing the outside air temperature has adjusted and it will be in one step 120 a temperature offset T_ktm_offset, which in a read / write memory is stored, the value O ° C assigned, and the method in a step 125 continued.

However, the engine shutdown time t_maz was shorter or equal to the given time, so directly in one Step 125 measurands and stored values from the Read-write memory accepted and there is a maximum selection between the measured value of the outside air temperature T_aluft and a last saved Value of fuel temperature T_ktm (old) instead, where Maximum selection means that the larger of the two Values in the further steps of the process as worth is used for the outside air temperature. Thus takes into account that with an external heating of the Fuel, for example, by heating during the Day or sun heating, the actual fuel temperature can be greater than the outside air temperature.

Then, in step 130, an operation counter becomes started. It should be noted that the parameter T_aluft in the described embodiment Represents a key figure, since this parameter is independent of dynamic parameters such as vehicle speed, affects fuel temperature the most and otherwise also on other parameters such as engine temperature Influences.

After waiting t_ini_kttm, after which one Has set equilibrium state (step 140), a check is carried out in a step 145 as to whether a Level sensor (not shown) is defective. Is this the case, the value of the fill level becomes in a step 147 on the last trip fs_tank_v into a variable for the value of the current level fs_tank accepted; otherwise step 150 follows (see Fig. 2b).

In step 150 in FIG. 2b it is checked whether a refueling process occurred during a business interruption Has. To do this, the difference between the currently measured tank level fs_tank and that the read / write memory taken over during the last trip determined tank level fs_tank (old). If this difference is greater than a specifiable one Value d_fs_tlfz, it is assumed that a refueling has occurred, and in step 155 one becomes Variables for the refueling detection b_kttm der Assigned value '1'. This variable b_kttm is used later in step 210 as one of the selection criteria for whether a refueling process has taken place and then an approximate value for the fuel temperature is determined.

The check then follows in a step 160, whether an outside air temperature sensor is defective. is the difference determined in step 150, however, is smaller as a predeterminable value d_fs_tlfz, it is directly in the Step 160 checks if the outside air temperature sensor is broken. If so, it will be in one step 290 of the variables for the outside air temperature T_aluft assigned the value 20 ° C. Then there is a step 180, in which it is checked whether the motor is shorter than one Predefinable threshold time, for example 30 minutes, in operation was, that is, whether a criterion for a short Operating time is available.

If it turns out in step 160 that the outside air temperature sensor is not defective, the measured outside air temperature is assigned to the variable for the outside air temperature T_aluft in a step 170, followed by step 180. In step 180, the first step of the method is to check whether the criterion for a short operating time exists. After a short period of operation, the temperature has not yet reached equilibrium, so that the fuel temperature must not be redetermined.
Therefore, after a waiting time of 10 minutes in a step 325, the cycle from step 160 is carried out again.

If, on the other hand, it is found in step 180 that the operating time of the engine was longer than 30 minutes, then in a step 190 it is only checked during the first run through of the method whether there is a criterion for a short shutdown time, with a time under a short shutdown time 30 minutes is understood.
With a short shutdown time, the fuel temperature has not changed compared to the last operating cycle of the engine, so that here too the fuel temperature must not be redetermined immediately.

Is after the first run of the procedure after Start the engine the criterion for a short stop time before, after a waiting time of for example 10 minutes in step 325 the cycle from step 160 performed again. The engine shutdown time was longer 30 minutes, for example, in a step 200 (Fig. 2c) checks whether the vehicle speed v_can is greater than zero.

This check is necessary because one stationary vehicle heat build-up, resulting in a Falsification of the specific fuel temperature leads. Therefore, there is no redefinition when the vehicle is stationary the fuel temperature, but after a Waiting time of, for example, 100 milliseconds in steps 320 the cycle in step 160 starting with the review of the temperature sensor repeated.

If the vehicle speed v_can is greater than zero, then a further check follows in a step 220 (FIG. 2c), whether the level sensor is defective. Is this the case, in a step 225 the variable the last saved value for the level fs_tank assigned to the level when driving fs_tank_v. A Check the level sensor at this point therefore necessary because for the following refueling detection a correct level when the engine is running is required. If the tank level sensor is defective the process can then be done automatically with at least one assigned level value continue.

After step 220, it is checked in step 210 whether refueling has taken place while the engine is running or during an interruption in operation. For this purpose, the difference between the currently measured tank level fs_tank and the last tank level fs_tank_v measured at a vehicle speed greater than zero is determined. If the difference is greater than a value d_fs_tel, refueling has taken place with the engine running. If the value of the variable b_kttm from step 155 is '1', refueling has taken place during the last business interruption. If it is found in step 210 that refueling has taken place, then in a step 300 the fuel temperature T_ktm is calculated as the mean value from the last calculated fuel temperature T_ktm_alt present in the read / write memory and the outside air temperature T_aluft. This is done according to the following equation, whereby the weighting instead of the factor ½ grds. can also assume other values: T_ktm = (T_ktm (old) + T_aluft) / 2.

Then in a step 310 the operating counter is set to zero and the procedure is carried out directly with a step 270 (Fig. 2d) continued.

In step 270, the transfer to this takes place Valid fuel temperature T_ktm in the Read / write memory as fuel temperature T_ktm (old), the variable for fueling detection b_kttm is set to '0'. Then, if the Engine is still operating, which is in a step 280 is checked, the cycle for determining the fuel temperature in step 320 after a wait of Repeated 100 milliseconds from step 160.

Resetting the operation counter in step 310 causes that the procedure in the next determination cycle from step 180 is carried out exactly as if it were Engine has been restarted and the criterion for one short operating times. Thus, in step 325 the procedure in the first run only after a waiting period continued from 10 minutes.

Did the check in step 210 show that none Refueling has been carried out, the procedure for Redefine the fuel temperature with a Step 230 continues (Fig. 2c). In step 230 the variables for the fill level while driving fs_tank_v the value of the measured level fs_tank assigned.

The check is then carried out in a step 240 on a geographical change in altitude. This is shown in detail in FIG. 3. The verification, whether there has been a change in altitude, starts with a step 2410 in FIG. 3. The altitude can be carried out with measures known per se, for example by means of a Pressure sensor based on the usual pressure dependency the outside air p_aluft can be determined. In one Step 2420 checks whether there is a decrease in altitude is present, that is, it is checked whether, for example a passport descent takes place. Is this the If so, in a step 2450 the temperature offset T_ktm_offset set to zero, then is checking for a change in altitude in Step 2460 ends and the method of determining fuel temperature continues to step 250 (see Fig. 2d). However, there is no decrease in altitude before, it is checked in a step 2430 whether there is an increase in altitude. Then this is the case when the vehicle is on a pass. If there is an increase in altitude, then in step 2440 the temperature offset T_ktm_offset assigned the value 5. This temperature offset later in a step 250 the one in a Circuit calculated fuel temperature T_ktm added. This takes into account the fact that the outside air temperature increases faster during a pass decreases as the fuel temperature of the Outside air temperature can adjust.

The check is then carried out in a step 2460 Altitude change ended and step 250 follows in Fig. 2d. In step 250, the fuel temperature T_ktm as a function of outside air temperature T_aluft, one Attenuation in a mathematical filter "A" which the series of the vehicle and the influence of the operating time of the engine to the increase in fuel temperature considered, depending on the bodywork and Engine series can be different, and one Attenuation in a mathematical filter "B", which is the Fuel temperature depending on the level of the tank, the tank level fs_tank and the engine shutdown time t_maz considered, calculated. To the so determined The value of the fuel temperature becomes the value of the temperature offset T_ktm_offset added. Subsequently is checked in a step 260 (FIG. 2c) whether the thus calculated fuel temperature T_ktm within a predeterminable temperature interval is (minimum / maximum limitation).

4 is a flowchart of a method for Minimum / maximum limitation of the fuel temperature according to Step 260 shown in detail. The procedure starts in step 2610. In step 2620 there is a check whether the one determined in step 250 Fuel temperature T_ktm is greater than a specifiable Maximum value T_ktm_max. If so, so is calculated in a step 2640 of the variables of the Fuel temperature T_ktm the value of the specifiable Allocated maximum temperature T_ktm_max and the process for minimum / maximum limitation in one step 2660 ended, step 270 (FIG. 2) follows in which in the read / write memory of the variable T_ktm (old) certain fuel temperature T_ktm and the variable the value for the operating temperature detection b_kttm Zero is assigned. Returns the check in step 2620 that the determined fuel temperature T_ktm not greater than the specifiable maximum value T_ktm_max is checked in a step 2630, whether the fuel temperature T_ktm is less than a Predeterminable minimum value T_ktm_min. If this is the case, then in a step 2650 the variable for the fuel temperature T_ktm the value of the minimum temperature T_ktm_min assigned.

Then, in step 2660, the procedure for minimum / maximum limitation finished and step follows 270 (Fig. 2).

2d, the value of the value determined in this way is determined at step 270 Fuel temperature T_ktm as a variable T_ktm_alt stored in the read / write memory. Of Furthermore, the variable for the fueling detection b_kttm assigned the value zero and saved. It is then checked in step 280 whether the engine is still in operation, this is not the case the process ends (step 290). Otherwise it will The above-mentioned method for determining the fuel temperature after a waiting time of 100 milliseconds carried out again from step 160 in FIG. 2a (Step 320).

It is understood that the individual process steps to determine the fuel temperature T_ktm also in in a different order. Also is quite possible to combine different steps can, the results from ramifications and cached queries in corresponding variables to be in a final calculation to be considered. With the used time or temperature information is only about exemplary specifications, which of course in their size can be changed.

Furthermore, it goes without saying that the detection of a Refueling situation after a business interruption and the detection of a refueling situation while running Engine can be combined. This will both when refueling during a business interruption as well as one with the variable engine running b_kttm assigned the value '1', which in later Decision steps or calculations involved becomes.

Preferably serve to identify a refueling process the tank level, the vehicle speed and the tank level during the last trip as initialization values for a series of from known logic operations and calculations in circuits.

In principle, the approximate calculation of the Fuel temperature after a refueling process too the refueled quantity are taken into account. Especially with a larger amount of fuel the influence of changes the outside air temperature to the fuel temperature is lower and thus a correction of the calculated Size can be done with the amount of fuel.

In the flow diagrams shown in FIGS. 1 to 3, can be assumed in most cases be that the measured values in a known Processor of the vehicle are present and that also known messages about a sensor defect (Level sensor or temperature sensor) are available stand.

The counter for the engine shutdown time is when switching off the engine started, and stopped as soon as the engine is started again. The parking time determined in this way becomes a variable in the read / write memory t_maz saved.

It is understood that besides those mentioned in the examples Measured variables or correction variables also other Available sizes to optimize the determination the fuel temperature T_ktm can be. Furthermore, it goes without saying that that Method also for determining a temperature of a any liquid in any container can be carried out. In place or in addition at least one further heat and / or cold-generating source, for example an air conditioning system or a cooling unit of the engine can be considered.

The embodiment of a characteristic diagram shown in FIG. 5 can contribute to the purpose already mentioned the procedure described above can be used. In the embodiment is T_ktm over T_aluft and fs_tank plotted, with the family of curves shown is parameterized over time t. The one in the characteristic diagram shown dependence on T_ktm as a function The above-described model calculation is from T_aluft and fs_tank based. In cases where the shown Parameters are already recorded in the control unit, the characteristic diagram can be generated automatically and T_ktm without further measures from this machine be read. It should be noted that the characteristic diagram in the case of n-1 additional parameters and in the shown parameterization with time t n-dimensional is trained.

Claims (22)

Method for the emission-monitoring operation of a storage container storing a volatile medium, in particular a fuel storage tank of a motor vehicle, a leak test of the storage container being carried out temporarily, characterized in that the temperature of the medium is determined temporarily or cyclically using a model calculation using at least one parameter, in particular the ambient temperature and is either included as a correction quantity in the leak test or the leak test is only carried out if the temperature of the medium determined is within a predeterminable temperature interval. A method according to claim 1, characterized in that the fill level of the storage container is used as a further parameter. Method according to Claim 1 or 2, characterized in that in the case of a motor vehicle, at least one operating variable of the motor vehicle is used as a further parameter. Method according to Claim 3, characterized in that at least one characteristic date relating to the vehicle series is used as a further characteristic variable. A method according to claim 3 or 4, characterized in that the shutdown time of a motor vehicle engine is included in the model calculation of the temperature of the medium, a series-specific cooling curve being stored and used as the initial value for the engine temperature when the motor vehicle engine is restarted. Method according to one of the preceding claims, characterized in that the temperature of the medium modeled on the basis of the at least one parameter is stored in the form of at least one parameter diagram via the at least one parameter. Method according to one of the preceding claims, characterized in that the temperature of the medium is only determined from the at least one parameter when the at least one parameter lies within a predefinable range of variance. Method according to one of claims 3 to 7, characterized in that the temperature of the medium is only determined when the vehicle speed and / or the operating time of the motor vehicle engine exceed a predetermined limit. A method according to claim 8, characterized in that the limit value is determined depending on the series of the motor vehicle engine and / or the body shape of the vehicle, in particular for individual vehicle series. Method according to one of the preceding claims, characterized in that a temperature value of the medium determined during operation of the storage container and / or the vehicle is temporarily stored and compared with a measured, current ambient temperature during a subsequent commissioning of the storage container and / or the vehicle and up to a the subsequent determination of the temperature of the medium using the model calculation, the larger of the two values being used as the initial value for the temperature of the medium. Method according to one of the preceding claims, characterized in that a change in the fill level of the storage container due to refueling is recorded and taken into account in the model calculation. A method according to claim 11, characterized in that the refueling is recognized in that after the start of the motor vehicle engine, the difference between the current tank fill level and a buffered tank fill level value exceeds a predefinable threshold value. A method according to claim 11 or 12, characterized in that the amount of refueled medium is included in the model calculation when the temperature of the medium is recalculated. Method according to one of the preceding claims, characterized in that, in the event of a detected failure of a temperature or level sensor of an associated temperature variable in the model equation, a predeterminable replacement value is assigned or a currently determined temperature value of the medium is replaced by a stored temperature value. Method according to one of the preceding claims, characterized in that a plausibility check is carried out, in which a current temperature value of the medium is compared with predeterminable upper and / or lower limit values and is only assumed to be correct if the temperature value lies within these limit values. A method according to claim 15, characterized in that when one of the limit values is exceeded, the temperature value is set equal to one of the limit values themselves. Method for determining the temperature of a volatile medium stored in a storage container, in particular the temperature of fuel stored in a fuel storage tank of a motor vehicle, characterized in that the temperature of the medium is based on at least one parameter, in particular the ambient temperature, by means of a model calculation according to one of the preceding claims is determined. Circuit, in particular binary-logic circuit, characterized by circuit means for executing the method according to one of claims 1 to 16. Circuit according to claim 18, characterized by at least two stages, each stage representing a filter for the influence of the respective parameter on the temperature of the medium and wherein the attenuation of the respective filter varies depending on the parameters and the correction variables dependent on the environment. Circuit according to claim 19, characterized by at least two filters on which the model calculation is based, the ambient temperature and / or the altitude of the storage container or the vehicle being incorporated into a first filter, and the filling level of the storage container and / or the vehicle parking time and / or being included in the at least second filter / or the vehicle engine shutdown time and / or the operating time of the storage container or of the motor vehicle. Control device, characterized by a control program for executing the method according to one of claims 1 to 16. Control device according to claim 21, characterized by a read / write memory (RAM) for storing the at least one characteristic variable diagram and / or for temporarily storing a determined temperature value of the medium.

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