EP1315894B1 - Mixture adaptation method for internal combustion engines with direct gasoline injection - Google Patents

Description

State of the art

It is already known in the regulation of Fuel / air ratio for internal combustion engines a Precontrol with a control to superimpose. Next is known, from the behavior of the control variable more Derive correction values for mismatches of the Pre-control to changed operating conditions too compensate. This compensation is also called adaptation designated. For example, US 4 584 982 describes a Adaptation with different adaptation sizes in different areas of the load / speed spectrum of a Internal combustion engine (range adaptation). The different Adaption variables are aimed at the compensation different mistakes. Leave for cause and effect There are three types of error: error of one Hot film air flow meter have a multiplicative effect on the Fuel metering off. Leakage influences have an additive effect per unit of time and error in the compensation of the Tightening delay of the injection valves have an additive effect Injection.

According to legal regulations, emissions-related errors should be considered be recognized with on-board means and if necessary should a fault lamp will be activated. The mixture adaptation becomes also used for fault diagnosis. Is for example the Correction intervention of the adaptation too large, this suggests a mistake.

Over the life span, the copy spread and at Non-regulated probe heating gives way to the measured Lambda value of the physically available lambda value Engines with gasoline direct injection mainly in Shift operation.

Since the mixture adaptation is the measured lambda for learning of the error is the adaptation in the Shift operation not effective. For the adaptation will therefore switched to the homogeneous operation and the Mixture adaptation activated.

From DE 1 98 50 586 is a motor control program known that switching between shift operation and Homogeneous operation controls.

In shift operation, the engine with a strong layered cylinder charge and high excess air operated to the lowest possible fuel consumption to reach. The stratified charge is delayed by a late Fuel injection achieved in the ideal case Splitting the combustion chamber into two zones leads: the first Zone contains a combustible air-fuel mixture cloud at the spark plug. It is surrounded by the second zone, the consists of an insulating layer of air and residual gas. The potential for optimizing consumption results from the Possibility of avoiding the engine Charge change losses largely unthrottled to operate. The shift operation is at comparatively low load preferred.

At higher load, if the performance optimization in the Foremost, the engine becomes more homogeneous Cylinder filling operated. The homogeneous cylinder filling results from an early fuel injection during the suction process. As a result, stands until the burning a longer time for mixture formation available. The Potential of this mode for performance optimization results for example, from the exploitation of the whole Combustion chamber volume for filling with combustible mixture.

With regard to the known adaptation, there are several activation:

For example, the engine temperature must Have reached switch-on temperature threshold and the Lambda probe must be ready for operation. Next must the current values of load and speed in certain Lie areas in which each is learned. This is For example, from US 4,584,982 known. Furthermore must Homogenous operation present. After the familiar program is Switching from shift operation to homogeneous operation not dependent on a fault in the system.

The invention aims at the period in which the engine optimal consumption can be driven in shift operation, too enlarge. Switching to homogeneous operation for diagnostics reduces the consumption advantage of Direct fuel injection, since the homogeneous operation is less favorable than the shift operation. A Switching to homogeneous operation increases the Fuel consumption therefore, if no error, unnecessary. It should be avoided as much as possible, without to worsen the discovery of exhaust-related errors.

This effect is achieved with the features of claim 1 achieved.

• bei dem im Homogenbetrieb eine Gemischregelung und eine Adaption der Gemischregelung stattfindet
• und bei dem zwischen den Betriebsarten in Abhängigkeit von einer Soll-Betriebsart umgeschaltet wird, die aus einer Mehrzahl von Betriebsartenanforderungen ermittelt wird, wobei jeder der Betriebsartenanforderungen eine Priorität zugeordnet ist
• und bei dem die Ermittlung der Soll-Betriebsart in Abhängigkeit von den Prioritäten der Betriebsartenanforderungen durchgeführt wird,
• wobei kurzzeitig auch außerhalb der normalen Einschaltbedingungen einer bereichsabhängigen Adaption auf Homogenbetrieb mit Aktivierung einer temperaturabhängigen Adaption umgeschaltet wird
• und bei dem eine Abweichung der Adaptionsgröße von ihrem neutralen Wert während der kurzzeitigen Aktivierung der temperaturabhängigen Adaption als Fehlerverdacht gewertet wird und bei dem das Motorsteuerungsprogramm beim Vorliegen eines Fehlerverdachtes die Priorität der bereichsabhängigen Adaption unter normalen Einschaltbedingungen heraufsetzt.

In detail, a method for compensating for maladjustments of the pilot control of a fuel metering (adaptation) for an internal combustion engine is disclosed, which is operated in the at least two different operating modes homogeneous operation and stratified operation,

• in which a mixture control and an adaptation of the mixture control takes place in homogeneous operation
• and switching between modes in response to a desired mode determined from a plurality of mode requests, wherein each of the mode requests is assigned a priority
• and in which the determination of the desired operating mode is carried out as a function of the priorities of the operating mode requirements,
• wherein, for a short time outside the normal switch-on conditions, an area-dependent adaptation to homogeneous operation is switched over with activation of a temperature-dependent adaptation
• and in which a deviation of the adaptation value from its neutral value during the short-term activation of the temperature-dependent adaptation is evaluated as a suspected error and in which the engine control program increases the priority of the range-dependent adaptation under normal switch-on conditions in the presence of an error suspicion.

An embodiment provides that the kurzeitige Mixture adaptation below the minimum temperature of area-dependent adaptation is activated.

Another embodiment provides that the Minimum temperature of the range-dependent adaptation greater or equal to 70 ° Celsius.

Another embodiment provides that the short-term Mixture adaptation for a time in the range of about 10 to 20 Seconds is activated.

Another embodiment provides that the physical urgency is withdrawn if the Error in normal range-dependent mixture adaptation has been learned, so that the area-dependent Mixture adaptation from the engine control program at normal Urgency is released.

Another embodiment provides that the value of Temperature-dependent short-term adaptation when stopping the Cars is maintained and during the initialization phase after the next start around the normal range-dependent mixture adaptation learned value is reset.

Another embodiment provides that the operating-parameter-dependent (area-dependent) Mixture adaptation multiplicative and / or additive to the Fuel metering acts.

Another embodiment provides that the or Values of the range-dependent adaptation above one Temperature threshold to be renewed and on the Fuel metering regardless of the temperature act.

A further embodiment provides that the formation of the Error suspected the deviation of the current temperature-dependent adaptation factor of one Long-term adaptation factor is formed.

The invention is also directed to an electronic Control device for carrying out at least one of the above specified methods and embodiments.

An essential part of the invention is a short-term mixture adaptation, which is also outside the normal Switch-on conditions of the adaptation, in particular below the minimum temperature of the range-dependent adaptation. According to the short-term mixture adaptation only for a very short time in the range of about 10 to 20 seconds activated. If there is an error, the correction quantity becomes the short-term temperature-dependent adaptation of hers deviate from neutral value.

The deviation is according to the invention in the context of Operating mode control program the urgency of normal mixture adaptation up. If then their Running conditions are met, the normal Mixture adaptation started comparatively quickly.

If the error is in the normal domain-dependent Mixture adaptation has been learned, the physical Urgency withdrawn and that runs range-dependent mixture adaptation only if they are derived from the Engine control program with normal urgency is released.

Since the temperature-dependent short-term adaptation when turning off the car retains its value and at the next start again in the adapted state is wrong, it becomes during the initialization phase after the next start within the scope of the normal domain Mixture adaptation learned value reset.

This has the advantage that in the unadapted state immediately the physical urgency of the normal adaptation increases.

Since the temperature-dependent adaptation in the normal state only 3 to 4% correction is to be the maximum of Integrators depending on the learned error down or corrected above, so that for example at a 20% learned error only 5% correction is allowed.

The invention provides the following advantages:

In the faultless condition is only in large time intervals in switched to homogeneous operation. In faulty condition When the engine is cold first very short and then long Time intervals drove. The short time intervals are at Unlearned error repeated after startup. At the learned mistakes will be again at long intervals Homogeneous operation. In the method of the invention is only very short in the most economical Homogenous mode switched and the suspected error Temperature-dependent mixture adaptation activated immediately. If there is no error in the system, the mixture adaptation becomes less frequently activated, so that the period lengthens, in where the engine is operated optimally in shift operation can be.

The following is an embodiment of the invention explained with reference to the drawing.

Fig. 1 shows the technical environment of the invention. Fig. 2 illustrates the formation of a fuel metering signal the basis of the signals of FIG. 1 and FIG. 3 discloses the Formation of a temperature-dependent adaptation variable, as they are is used in the invention and Fig. 4 represents an embodiment of the invention in the form of Function blocks.

1 in FIG. 1 represents an internal combustion engine with a suction pipe 2, an exhaust pipe 3, a Fuel metering means 4, sensors 5 - 8 for Operating parameters of the engine and a control unit 9. The Kraftstoffzumessmittel 4 can for example from a Arrangement of injectors for direct injection of fuel into the combustion chambers of the internal combustion engine consist.

The sensor 5 provides the controller with a signal on the from Engine aspirated air mass ml. Sensor 6 delivers Engine speed signal n. Sensor 7 sets the engine temperature T ready and sensor 8 provides a signal Us over the Exhaust gas composition of the engine. Out of these and optionally further signals via further Operating parameter of the engine is the control unit next to Further control variables the fuel metering signals ti to Control of the fuel metering 4 so that a desired behavior of the engine, in particular a desired exhaust gas composition sets.

FIG. 2 shows the formation of the fuel metering signal. block 2.1 represents a map, the speed n and the relative air charge rl is addressed and in the Pre-tax values rk for the formation of the Fuel metering signals are stored. The relative Air filling rl is based on a maximum filling of the combustion chamber with air and thus gives a fraction of the fraction the maximum combustion chamber or cylinder filling. she will essentially formed from the signal ml. rk corresponds the amount of fuel allocated to the air volume rl.

Block 2.2 shows the known multiplicative Lambda control adjustment. A mismatch of fuel quantity the amount of air is reflected in the signal Us of the exhaust gas probe. For this purpose, a controller 2.3 forms the control manipulated variable fr, via the intervention 2.2 reduces the mismatch.

From the signal thus corrected, in block 2.4, the Zumesssignal, for example, a drive pulse width for the injection valves are formed. Block 2.4 represents the conversion of relative and corrected amount of fuel in a real drive signal taking into account fuel pressure, Injection valve geometry etc.

Blocks 2.5 to 2.9 represent the known operating-parameter-dependent (range-dependent) mixture adaptation, which can act multiplicatively and / or additively. The circle 2.9 should represent these 3 possibilities. The switch 2.5 is opened or closed by the means 2.6, wherein the means 2.6 operating parameters of the internal combustion engine such as temperature T, air mass ml and speed n are supplied. Means 2.6 in conjunction with the switch 2.5 thus allows a operating parameter range-dependent activation of the three adaptation options mentioned. The formation of the adaptation engagement on fuel metering signal formation is illustrated by blocks 2.7 and 2.8. Block 2.7 forms the mean value frm of the control manipulated variable fr when the switch 2.5 is closed. Deviations of the mean value frm from the neutral value 1 are taken over by the block 2.8 into the adaptation intervention variable fra. For example, the control manipulated variable fr initially goes against 1.05 due to a mismatching of the precontrol. The deviation 0.05 from the value 1 is adopted by the block 2.8 in the value fra of the adaptation intervention. In a multiplicative fra intervention then fra goes against 1.05, with the result that again goes to 1. The adaptation ensures that misadjustments of the feedforward control do not have to be compensated for every change of operating point.
This adaptation of the adaptation value fra is carried out at high temperatures of the internal combustion engine, for example above a cooling water temperature of 70 ° Celsius, then closed switch 2.5; Once adjusted, fra also acts with open switch 2.5 on the formation of the fuel metering signal ..

This known adaptation is in the context of the invention the further correction frat supplements that in the linkage 2.10 becomes effective.

An embodiment of the frat formation is shown in FIG. 3 shown. Block 3.1 provides the deviation of the mean Control variable frm from value 1 to an integrator block 3.2. Block 3.3 activates the integrator for comparatively low engine temperatures T from an interval TMN <T < TMX. For example, TMN as the lower interval limit 20 ° Celsuis; TMX as the upper interval limit for example, correspond to the temperature at which the conventional adaptation via closing the switch 2.5 is activated. A typical value for this temperature is 70 ° Celsius.

The output value of the integrator supplies with the value frak a measure of the mismatch with comparatively cold Engine.

This value is when the engine is cold Fuel metering signal formation takes into account without that at high temperatures differences to the known adaptation when the engine is warm.

This is exemplified by blocks 3.4 to 3.6 and Reached 2.10.

The essential thing in this context is first Linking the integrator output frak with a temperature dependent size ftk. In the example, ftk a multiplicative varying between zero and one Correction. The value zero results with a warm engine, that is, at T> TMX. Then the minimum selection in the Block 3.7 the value TMX. In block 3.8 results as Difference of TMX and TMX the value zero, which is the Quotient formation in block 3.9 is supplied as a counter. Block 3.8 accordingly returns the value zero for the size the temperature-dependent variable ftk. At this value ftk = Zero, the value 1 is added in block 3.6. The sum frat therefore has the value 1 and changes in the multiplicative Link in block 2.10 the fuel metering signal formation not with warm engine. In other words, with a warm engine ftk acts on frak maximally attenuating. When cold Motor with for example T = zero ° Celsius delivers the Minimum selection the value zero and the following Quotient the value 1. ftk is then neutral and acts minimally attenuating or not attenuating frak. To add the 1 in block 3.6 for this case to compensate, in block 3.4, a subtraction of 1. If the engine is cold (T = zero), then frak acts as (frak-1) * 1 + 1 = frak unchanged and thus not weakened on the fuel metering signal formation. With others Words: the further adaptive (temperature-dependent) correction only works when the engine is cold. Between the illustrated Extreme values, the correction varies steadily.

The map 3.10 provides values K for the Integration speed in the integrator 3.2 depends on Values for drl and n. For example, K becomes all the more smaller, the bigger drl is. drl is the change of sucked air mass, for example, at Transitional operating conditions is particularly large. To this Way, mismatches affect in Transient operating conditions only in a weakened form the adaptation.

As the engine temperature changes and that in the integrator learned value frak should be independent of the temperature, is the frm deviation of one with the factor ftk multiplied.

Fig. 4 represents an embodiment of the invention in the form of function blocks.

Block 4.1 stands for the formation shown in FIG the sizes frat and frak. To the formation of the error suspicion is in the range of temperature-dependent mixture adaptation first, a long-term adaptation factor fratia formed (block 4.2). This is to some extent the share of Cold adaptation factor frak, always with cold engine occurs. If the temperature-dependent adaptation in the error-free state always a similar value, for example, a Value of 2.5%, this value does not show any Error. This always occurring value is in the control unit saved.

Furthermore, the deviation of the current temperature-dependent adaptation factor frak from the long-term adaptation factor fratia is formed to form the error suspicion: dfrat = amount (frak - fratia)

The difference formation and the amount formation are by the Blocks 4.3 and 4.4 are shown. Subsequently, a Comparison of dfrat with a suspected error threshold FVLRAS (Block 4.5). If this is exceeded, the condition becomes B-fvlra is set in block 4.6 via a flip-flop. Of the Suspected error corresponds to a high urgency for the normal, warm engine adaptation. Due to the high urgency resulting from the setting of the reasoned Error suspected in the context of the short-term temperature-dependent adaptation has been subsequently, as soon as the remaining switch-on conditions for the normal mixture adaptation, accelerated in the Homogenous mode switched and the normal mixture adaptation activated (block 4.7).

Claims (10)

1. Method for compensating incorrect adaptations of the pilot control of a fuel metering system for an internal combustion engine which is operated in the at least two different operating modes of homogeneous operating mode and stratified operating mode,

   wherein in the homogenous operating mode mixture control and adaptation of the mixture control take place,

   and wherein switching over is carried out between the operating modes as a function of a setpoint operating mode which is determined from a plurality of operating mode requirements,
   wherein each of the operating mode requirements is assigned a priority,

   and wherein the determination of the setpoint operating mode is carried out as a function of the priorities of the operating mode requirements,

   wherein switching over to homogeneous operating mode with activation of a temperature-dependent adaptation is also briefly carried out outside the normal switch-on conditions of a range-dependent adaptation,

   and wherein a deviation of the temperature-dependent adaptation variable from its neutral value during the brief activation is evaluated as a suspected fault, and wherein, when a suspected fault is present, the engine control program increases the priority of the adaptation under normal switch-on conditions.
2. Method according to Claim 1, characterized in that the brief mixture adaptation is activated below the minimum temperature of the range-dependent adaptation.
3. Method according to Claim 2, characterized in that the minimum temperature of the range-dependent adaptation is greater than or equal to 70° Celsius.
4. Method according to Claim 1 or 2, characterized in that the brief mixture adaptation is activated for a time in the range between approximately 10 and 20 seconds.
5. Method according to Claim 1, characterized in that the physical urgency is reduced if the fault has been learnt in the normal, range-dependent mixture adaptation so that given normal urgency the range-dependent mixture adaptation is enabled by the engine control program.
6. Method according to Claim 1, characterized in that the value of the temperature-dependent brief adaptation is retained when the car is shut down and is reset by the value learnt within the scope of the normal range-dependent mixture adaptation, during the initialization phase after the next start.
7. Method according to one of the preceding claims, characterized in that the operating-parameter-dependent, for example range-dependent mixture adaptation has a multiplicative and/or additive effect on the metering of fuel.
8. Method according to one of the preceding claims, characterized in that the value or the values of the range-dependent adaptation are refreshed above a temperature threshold and act on the metering of fuel independently of the temperature.
9. Method according to one of the preceding claims, characterized in that in order to form the suspicion of a fault, the deviation of the current temperature-dependent adaptation factor from a long-term adaptation factor is formed.
10. Electronic control device having means which are configured for carrying out at least one of the methods according to Claims 1 to 9.

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