DE102007026948A1 - Fuel ethanol content determining method for internal combustion engine of motor vehicle i.e. flexible fuel vehicle, involves determining ethanol content of fuel depending on determined loading degree of activated carbon filter - Google Patents

Abstract

The method involves determining a loading degree of an activated carbon filter (64) for filtering hydrocarbon vaporized in a fuel (52) in a fuel tank (50). Ethanol content of the fuel is determined depending on the determined loading degree of the activated carbon filter. A petrol content of the fuel is determined depending on the loading degree of the carbon filter. The ethanol content of the fuel is determined depending on the determined petrol content. The carbon filter is rinsed with fresh air. A combustion process of the internal combustion engine is executed with fresh air. An independent claim is also included for a device for determining ethanol content of fuel in a fuel tank of an internal combustion engine.

Description

The The invention relates to a method and a device for determining of an ethanol content of a fuel in a fuel tank of a fuel Internal combustion engine.

One Flexible Fuel Vehicel (FFV) is a vehicle that is both pure Gasoline as well as with various similar fuels, For example, an ethanol-gasoline mixture can be operated.

From the US 518 29 42 A For example, a method for determining an ethanol content in a fuel mixture is known. For this purpose, a sample of the fuel mixture is heated and recorded its evaporation temperature. Depending on the evaporation temperature is closed to the ethanol content of the fuel.

It The object of the invention is a method and a device for Determining an ethanol content of a fuel to provide the or simply a precise determination of the Ethanol content possible.

The Task is solved by the characteristics of the independent Claims. Advantageous embodiments of the invention are specified in the dependent claims.

The Invention is characterized by a method and an apparatus for determining an ethanol content of a fuel in a fuel tank an internal combustion engine. A degree of loading of an activated carbon filter for filtering hydrocarbons vaporized from the fuel is determined. Depending on the determined degree of loading the ethanol content is determined.

This simply allows a precise determination of the Ethanol content of the fuel. In particular, allows this involves determining the ethanol content without an ethanol content sensor. This can help to manufacture the internal combustion engine cost-effectively.

In an advantageous embodiment is dependent on the Degree of loading a gasoline content of the fuel determined. Dependent from the determined gasoline content becomes the ethanol content of the fuel determined. This simply adds to the ethanol content to determine precisely.

In A further advantageous embodiment of the activated carbon filter flushed with fresh air. The with the hydrocarbons enriched fresh air is a combustion process of the internal combustion engine fed. Depending on a controller rash a lambda controller for regulating an air / fuel ratio of an exhaust gas from the combustion process becomes the ethanol content of the fuel. This simply allows the Degree of loading without a loading degree sensor precisely determine. This can help keep the engine cost-effective manufacture.

In A further advantageous embodiment of the activated carbon filter flushed with fresh air. After a predetermined period of time the activated carbon filter is rinsed again with fresh air and then the ethanol content is determined. This helps that boundary conditions in several determinations of ethanol content are approximately equal. This contributes to that the ethanol content can be determined very precisely.

In A further advantageous embodiment of the activated carbon filter rinsed within a driving cycle and rinsed again. During the same driving cycle, the ethanol content is determined. This contributes to the fact that the boundary conditions in the several Analyzes of ethanol content are almost the same. This carries Furthermore, the ethanol content can be determined even more precisely is.

In In a further advantageous embodiment, the ethanol content depending on at least one detected temperature of the internal combustion engine determined. This simply adds to the ethanol content especially to determine precisely. The temperature is for example a temperature of the fuel in the fuel tank and / or a Coolant temperature of a coolant of the internal combustion engine.

In In a further advantageous embodiment, the ethanol content depending on a level of the fuel determined in the fuel tank. This just adds to determine the ethanol content very precisely.

In In a further advantageous embodiment, the ethanol content determined depending on a tank pressure in the fuel tank. This simply adds to the ethanol content especially to determine precisely.

embodiments The invention are described in more detail below with reference to schematic drawings explained.

It demonstrate:

1 an internal combustion engine,

2 an inside view of an activated carbon filter,

3 a vapor pressure curve,

4 3 is a flow chart of a first program for determining an ethanol content of a fuel;

5 a flowchart of a second program for determining the ethanol content of the fuel.

elements the same construction or function are cross-figurative marked with the same reference numerals.

An internal combustion engine ( 1 ) comprises an intake tract 1 , an engine block 2 and an exhaust tract 4 , The internal combustion engine is preferably arranged in a motor vehicle.

The intake tract 1 includes a throttle 5 , from whose switching position depends fresh air into a collector 6 can be sucked. The fresh air in the collector 6 is about one, preferably several suction tubes 7 and via one, preferably several inlet channels to a cylinder Z1, preferably to a plurality of cylinders Z2-Z4. The internal combustion engine can also have any number of cylinders.

For injecting fuel 52 in the cylinder Z1-Z4 are one, preferably several injectors 18 arranged so that through the injectors 18 the fuel 52 from a fuel tank 50 the corresponding cylinders Z1-Z4 can be measured. The fuel 52 can with the injectors 18 in the suction pipes 7 be measured. Alternatively, the injectors 18 in a cylinder head 3 the internal combustion engine be arranged so that the fuel 52 directly corresponding combustion chambers of the cylinder Z1-Z4 can be assigned.

A fuel rail 60 supplies the injectors 18 with the fuel 52 , The fuel 52 can out of the fuel tank 50 via a low-pressure pump 56 and a high pressure pump 58 to the fuel rail 60 be pumped. The fuel tank 50 preferably has a filler neck 54 for filling the fuel 52 on. The fuel 52 includes an ethanol-gasoline mixture of any concentration.

A control device 25 is provided, which can determine operating variables of the internal combustion engine depending on measured variables of the internal combustion engine. Depending on the measured variables and / or the operating variables, one or more control signals for actuating actuators of the internal combustion engine are preferably generated. The control device 25 may also be used as an apparatus for determining an ethanol content ETH_PERC ( 4 ) of the fuel 52 be designated.

The sensors for acquiring the measured values are, for example, an air mass flow sensor 28 for detecting an air mass flow upstream of the throttle 5 , a lambda probe 42 whose measurement signal is representative of an air-fuel ratio of the exhaust gas of the internal combustion engine, a level sensor for detecting a fuel level FTL of the fuel 52 in the fuel tank 50 and / or a tank pressure sensor 72 , for detecting a tank pressure PRS_CAN ( 5 ) in the fuel tank 50 ,

The actuators are, for example, the throttle 5 , the injectors 18 , the low pressure pump 56 and / or a high pressure pump 58 and / or a CPS valve 70 ,

The CPS valve 70 serves to rinse an activated carbon filter 64 which is arranged in a housing and which is connected to the fuel tank 50 via a vent line 63 communicated. The activated carbon filter 64 is intended for filtering hydrocarbons HC ( 2 ), from the fuel 52 , in particular from the gasoline of the fuel 52 evaporate. A fuel vapor 62 , in particular the vaporized hydrocarbons HC from the fuel tank 50 be in the activated carbon filter 64 bound so that at an overpressure in the tank the pressure across the charcoal filter 64 and a fresh air line 66 on the housing of the activated carbon filter 64 can be reduced.

A loading level CL of the activated carbon filter 64 is representative of saturation of the activated carbon filter 64 , If the loading degree CL is preferably maximum, the activated carbon filter becomes 64 preferably rinsed. The activated carbon filter 64 is preferably purged by at a negative pressure in the intake tract 1 downstream of the throttle 5 the CPS valve 70 is opened, allowing fresh air through the fresh air line 66 through the activated carbon filter 64 and a rain pipe 68 towards the intake tract 1 is sucked. The enriched with the hydrocarbons HC fresh air is then fed to the combustion processes in the combustion chambers of the cylinders Z1-Z4.

A controller excursion of a lambda controller, which with the lambda probe 42 is coupled and which is provided for setting a predetermined air / fuel ratio of the exhaust gas, is representative of the degree of loading CL of the activated carbon filter 64 , Thus, depending on the controller deflection of the lambda controller, the degree of loading for the activated carbon filter 64 be determined. The degree of loading CL of the activated carbon filter is in particular representative of a gasoline content BENZ_PERC ( 5 ) of the gasoline in the fuel 52 , Depending on the fuel content BENZ_PERC of the fuel 52 can the ethanol content ETH_PERC of the force substance 52 be determined.

The gasoline content BENZ_PERC can depend on the degree of loading CL of the activated carbon filter 64 for example, based on a vapor pressure curve 80 ( 3 ) of the gasoline. The vapor pressure curve 80 is representative of a vapor pressure VAP_PRS of the gasoline at a gasoline temperature BEN_TEMP.

To determine the ethanol content ETH_PERC, a first program ( 4 ) for determining the ethanol content ETH_PERC on a storage medium of the control device 25 stored.

The first program is preferably started in a step S1, in which variables are initialized if necessary.

In a step S2, the loading level CL is determined, for example as explained above. Alternatively, the degree of loading of the activated carbon filter 64 also be determined with a loading degree sensor.

In a step S3, depending on the degree of loading CL, the ethanol content ETH_PERC of the fuel 52 determined.

In a step S4, the first program can be terminated. Preferably The first program is regularly in operation the internal combustion engine processed, for example, once during every driving cycle. In addition, the ethanol content ETH_PERC becomes the farm size stored on the storage medium and other vehicle functions for preferably optimal control of the internal combustion engine for Provided.

Alternatively or additionally, on the storage medium of the control device, a second program ( 5 ) to determine the ethanol content ETH_PERC. The second program is preferably started in a step S5 in which variables are initialized if necessary.

In one step 96 becomes an actuator CPS for adjusting the CPS valve 70 by means of one of the control device 25 opened OPEN open signal.

After rinsing the activated carbon filter 64 In a step S8, the actuator CPS for adjusting the CPS valve 50 controlled by a CLOSE closing signal so that the CPS valve 70 is closed.

In a step S9 is DUR for a predetermined period of time lingers.

Steps S6 to S9 serve to provide the same conditions for determining the ethanol content ETH_PERC before determining the ethanol content ETH_PERC. In particular, this ensures that the duration DUR, in which the loading level CL of the activated carbon filter 64 increasing, always the same.

In a step S10, the actuator CPS for adjusting the CPS valve 70 again controlled by the opening signal OPEN so that the CPS valve 70 opens.

In a step S11, which is preferably executed shortly after step S10, a lambda controller deflection LAM_SIG of the lambda controller is detected. The lambda controller can have hard-wired logic inside or outside the lambda probe 42 include and / or include software stored on the storage medium of the controller 25 is stored.

In a step S12, the degree of loading CL of the activated carbon filter is dependent on the detected lambda controller deflection LAM_SIG 64 determined.

In a step S13, depending on the degree of loading CL, the fuel content BENC_PERC of the fuel 52 determined. The gasoline content BENC_PERC can be determined particularly precisely if at least one temperature TEMP of the internal combustion engine is taken into account. For example, the temperature TEMP may be a temperature of the fuel 52 in the fuel tank 50 and / or a coolant temperature of a coolant of the internal combustion engine. Alternatively or additionally, the determination of the fuel content BENC_PERC can be further specified if the level of fuel level FTL 52 in the fuel tank 50 is taken into account. Alternatively or additionally, for particularly precise determination of the fuel content BENC_PERC, the tank pressure PRS_CAN in the tank 50 be taken into account. The measured quantities for specifying the determination of the fuel content BENC_PERC can each be detected individually by means of the corresponding sensors. Alternatively, only a part of the aforementioned measured variables can be detected and / or the further variables can be determined as operating variables as a function of the measured variables. The measured variables and / or operating variables can be input variables for a characteristic map, from which the gasoline content BENC_PERC can then be read out.

In a step S14, depending on the fuel content, BENC_PERC of the fuel 52 the ethanol content ETH_PERC determined. Alternatively, the map can be stored so that the ethanol content ETH_PERC can be read out directly.

In In a step S15, the second program can be ended. Preferably becomes the second program according to the first program regularly during operation of the internal combustion engine processed. In particular, the second program is preferred processed at least once during each drive cycle.

The Invention is not limited to the specified embodiments limited. For example, the internal combustion engine any subset of said sensors and / or actuators comprise or comprise further sensors and / or actuators. Further can be the first and / or the second program in each parent Be implemented programs or divided into subroutines be.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 5182942 A [0003]

Claims (9)

Method for determining an ethanol content (ETH_PERC) of a fuel ( 52 ) in a fuel tank ( 50 ) of an internal combustion engine, wherein a degree of loading (CL) of an activated carbon filter ( 64 ) for filtering fuel ( 52 ) Vaporized hydrocarbons (HC) is determined and in which, depending on the determined degree of loading (CL), the ethanol content (ETH_PERC) is determined. Method according to Claim 1, in which, depending on the degree of loading (CL), a gasoline content (BENZ_PERC) of the fuel ( 52 ) and in which, depending on the determined gasoline content (BENZ_PERC), the ethanol content (ETH_PERC) of the fuel ( 52 ) is determined. Method according to one of the preceding claims, in which - the activated carbon filter ( 64 ) is purged with fresh air, - the enriched with the hydrocarbons (HC) fresh air is supplied to a combustion process of the internal combustion engine, - depending on a controller deflection (LAM_SIG) of a lambda controller for controlling an air / fuel ratio of an exhaust gas from the combustion process, the ethanol content (ETH_PERC ) of the fuel ( 52 ) is determined. Process according to claim 3, in which - the activated carbon filter ( 64 ) is rinsed with fresh air, - after a predetermined period of time (DUR) the activated carbon filter ( 64 ) is rinsed again with fresh air and then the ethanol content (ETH_PERC) is determined. Process according to Claim 4, in which the activated carbon filter ( 64 ) is rinsed and rinsed within a driving cycle and during which the ethanol content (ETH_PERC) is determined during the same driving cycle. Method according to one of the preceding claims, in which the ethanol content (ETH_PERC) depends on at least a detected temperature (TEMP) of the internal combustion engine determined becomes. Method according to one of the preceding claims, in which the ethanol content (ETH_PERC) depends on a level (FTL) of the fuel ( 52 ) in the fuel tank ( 50 ) is determined. Method according to one of the preceding claims, in which the ethanol content (ETH_PERC) depends on a tank pressure (PRS_CAN) in the fuel tank ( 50 ) is determined. Device for determining an ethanol content (ETH_PERC) of a fuel ( 52 ) in a fuel tank ( 50 ) of an internal combustion engine, wherein the device is adapted to a degree of loading (CL) of an activated carbon filter ( 64 ) for filtering fuel ( 52 ) to determine vaporized hydrocarbons (HC) and to determine the ethanol content (ETH_PERC) depending on the determined degree of loading (CL).