DE102008016042A1 - Petrol and ethanol proportion determination method for fuel mixture for combustion in internal combustion engine of motor vehicle, involves determining proportion with consideration of lambda actual values and lambda expected values - Google Patents

Abstract

The method involves determining a lambda actual value (lambda-i2) from an exhaust gas (A) produced during a combustion, where a lambda expected value (lambda-e1) is determined according to a mixture of a defined amount of air (L1) with a base quantity (B1) of a fuel e.g. petrol. A lambda expected value (lambda-e2) is determined according to a mixture of the defined amount of the air with a base quantity (B2) of the fuel, where a fuel proportion (V) is determined with consideration of the lambda actual values and the lambda expected values.

Description

The The invention relates to a method for determining a quantitative ratio between a first fuel and a second fuel in one Fuel mixture.

modern Internal combustion engines can often work with several Fuels, such as premium gasoline, regular gasoline, diesel fuel, Alcohols such as methanol, ethanol, propanol, isobutanol u. a. operated become. For the performance of the internal combustion engine is the Calorific value of the combustible fuel-air mixture decisive. Desirable is the use of alcohols especially for the following reasons: Alcohols are suitable as a refining fuel for inferior gasolines. By adding, for example Methanol to normal gasoline can significantly increase the knock resistance so that with this mixture also higher compression internal combustion engines can be driven. It will be polluting Anti-knock agent dispensable.

alcohols In addition, because of the less toxic emissions In comparison with gasoline also increasingly for environmental reasons Importance. They can be made from coal and in a relatively cheap way produce renewable raw materials and therefore are also in distant Future in large quantities available. Especially Ethanol is environmentally friendly when it comes from vegetable products is gained (biological cycle). Alcohols are therefore one suitable extender for the only limited available Petroleum fuels.

at Alcohol, however, is the specific minimum air requirement for a complete combustion less than conventional Fuels. At the same sucked air quantity must the engine in alcohol or gasoline / alcohol mixing operation so a corresponding higher fuel quantity can be fed to a stoichiometric air-fuel ratio too to reach. This makes a corresponding adjustment of the mixture preparation device of the internal combustion engine required. However, where appropriate, alcohols be mixed in fluctuating proportions, or at least in the Refueling of different types of fuel in the motor vehicle tank must, according to the alcohol content in the fuel tank the required air-fuel ratio for one stoichiometric mixture for the mixture former be redetermined.

• – in einem ersten Verfahrensschritt die Brennstoffprobenmenge auf eine vorgegebene Temperatur erhitzt wird, bis die Brennstoffprobenmenge verdampft ist,
• – in einem zweiten Verfahrensschritt die nach der Verdampfung entstandene Druck- und/oder Volumen- und/oder Temperaturänderung durch einen oder mehrere Sensoren festgestellt wird und der oder jeder Sensorwert,
• – in einem dritten Verfahrensschritt mit im Steuergerät gespeicherten Bezugswerten für normalen Brennstoff verglichen wird und aus der Abweichung ein Korrektursignal gebildet wird,
• – in einem vierten Verfahrensschritt mittels des Korrektursignals Motorsteuerungsgrößen änderbar sind und dass
• – in einem fünften Verfahrensschritt das gebildete Korrektursignal gespeichert wird, bis es bei erneuter Brennstoffprobenmessung bestätigt bzw. geändert wird.

From the DE 40 31 009 C2 A method is known for using fuels with added alcohols for an internal combustion engine operated with an electronic mixture formation system, in which means a means for evaporating a fuel sample amount, a correction signal for changing the mixture composition is generated in a control device, wherein the correction signal is determined by

• In a first process step, the fuel sample amount is heated to a predetermined temperature until the fuel sample amount has evaporated,
• In a second method step, the pressure and / or volume and / or temperature change resulting after the evaporation is determined by one or more sensors and the or each sensor value,
• Is compared in a third method step with reference values for normal fuel stored in the control unit and a correction signal is formed from the deviation,
• - In a fourth step by means of the correction signal motor control variables are changeable and that
• - In a fifth method step, the correction signal formed is stored until it is confirmed or changed in another fuel sample measurement.

It It is an object of the invention to provide an improved method of determination a ratio of two fuels in a fuel mixture specify.

The The object is achieved by a method having the features of claim 1.

advantageous Further developments are the subject of the dependent claims.

at a method of determination according to the invention a quantity ratio between a first fuel and a second fuel in a fuel mixture is first a first base amount of the fuel mixture with a defined Air amount of combustion supplied in an internal combustion engine. In this case, a first lambda actual value becomes one during combustion resulting exhaust gas determined.

Subsequently becomes a second base set different from the first base set of the fuel mixture with the defined amount of air combustion supplied in the internal combustion engine. This is a second Lambda actual value determined from the exhaust gas produced during combustion, which necessarily differs from the first lambda actual value.

In accordance with a fictitious mixture of the defined air quantity with the first basic quantity of only the first fuel, a first lambda expected value can be calculated. A second lambda expectation value is accordingly assumed of a fictitious mixture of the defined air quantity with the second basic quantity of only the first fuel. The quantitative ratio is now determined taking into account the lambda actual values and the lambda expected values.

requirement is that the two fuels with respect to their specific stoichiometric air-fuel ratio, in which a lambda expectation value of 1 occurs, differ from each other. This condition is met, for example, with gasoline and ethanol, but also applies to most other possible fuel mixtures two fuels too.

Advantageous is that an evaporation of the fuel mixture and subsequent Determination of pressure and / or volume and / or temperature changes is not required by means of additional sensors. Of the Lambda actual value is used in modern motor vehicles with catalytic converters determined anyway, so that hardly any additional costs.

in the Below is an embodiment of the invention based a drawing explained in more detail.

there shows:

1 a schematic representation of an internal combustion engine with a lambda probe and a mixture preparation device and a control unit.

In 1 is a schematic representation of an internal combustion engine 1 with a lambda probe 2 and a mixture processing device 3 as well as a control unit 4 shown. The mixture preparation device 3 is supplied with a fuel mixture G and combustion air L, in which a first fuel and a second fuel are present in a quantity ratio V to be determined. Controlled by the control unit 4 leads the mixture preparation device 3 the internal combustion engine 1 a mixture of a first basic amount B1 of the fuel mixture G and a defined amount of air L1 to where the mixture is burned.

Exhaust gases A produced during combustion pass through the lambda probe on their way through an exhaust system 2 where a combustion air ratio, here called lambda actual value λ _i1 , is determined, for example based on an oxygen content or a carbon dioxide content in the exhaust gas A. The first lambda actual value λ _i1 becomes the control unit 4 fed.

In the control unit 4 a first lambda expected value λ _{e1 is} calculated taking into account the air amount L1 and based on the assumption that the first basic amount B1 contains only the first fuel, for example premium gasoline.

Subsequently, a second basic quantity B2 of the fuel mixture G, different from the first basic quantity B1, with the defined air quantity L1 of the combustion in the internal combustion engine 1 fed. The resulting during combustion exhaust gases A are in the lambda probe 2 to a second lambda actual value λ _i2 out, which necessarily differs from the first lambda actual value λ _i1 and again the control unit 4 is supplied.

There, a second lambda expected value λ _{e2 is} calculated taking into account the air amount L1 and based on the assumption that the second basic amount B1 contains only the first fuel. The quantity ratio V of the two fuels in the fuel mixture is then determined taking into account the lambda actual values λ _i1 , λ _i2 and the lambda expected values λ _e1 , λ _e2 .

1

internal combustion engine

2

lambda probe

3

Mixture preparation device

4

control unit

A

exhaust

B1

first base quantity

B2

second base quantity

G

Fuel mixture

L

combustion air

L1

air flow

V

ratio

λ _e1

first Lambda expected value

^λ e2

second Lambda expected value

λ _i1

first Lambda actual value

λ _i2

second Lambda actual value

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

• - DE 4031009 C2 [0005]

Claims (3)

Method for determining a quantity ratio (V) between a first fuel and a second fuel in a fuel mixture (G), characterized in that a first basic quantity (B1) of the fuel mixture (G) with a defined amount of air (L1) combustion in an internal combustion engine ( 1 ), wherein a first lambda actual value (λ _i1 ) is determined from an exhaust gas (A) produced during combustion, one of the first base amount (B1) different second base amount (B2) of the fuel mixture (G) with the defined Air volume (L1) of the combustion in the internal combustion engine ( 1 A second lambda actual value (λ _i2 ) is determined from the exhaust gas (A) produced during combustion, a first lambda expected value (λ _e1 ) corresponding to a mixture of the defined air quantity (L1) with the first basic quantity (B1) only the first fuel is determined and wherein a second lambda expected value (λ _e2 ) corresponding to a mixture of the defined air quantity (L1) with the second basic amount (B2) of only the first fuel is determined, wherein the quantity ratio (V) below Taking into account the lambda actual values (λ _i1 , λ _i2 ) and the lambda expected values (λ _e1 , λ _e2 ) is determined. Method according to claim 1, characterized in that that the determination of the quantity ratio (V) in a Motor vehicle is performed. Method according to one of claims 1 or 2, characterized in that the quantity ratio (V) the fuels gasoline and ethanol is determined.