DE102009010309B4 - Method for operating an internal combustion engine - Google Patents

Abstract

Method for operating an internal combustion engine, wherein in n working cylinders, where n = 1, 2,... Z, n is an integer and Z is a total number of working cylinders of the internal combustion engine, one reciprocating piston executes successive working cycles and at least one over a working cycle Performing single combustion, wherein each individual combustion of a cycle produces a total torque Trq and a total amount Q of heat, characterized by performing the following steps for each cycle and cylinder: (1) determining a setpoint for the total torque TrqDes; (2) determining a setpoint for the (3) determining an inverse efficiency factor setpoint according to the formula (4) comparing the inverse efficiency factor setpoint facTrq2QDes with a minimum inverse efficiency factor facTrq2QMIM in at least one single combustion, wherein the minimum inverse efficiency factor facTr q2QMIMin is determined from an Inverse Efficiency Factor versus Centers of Gravity of the individual combustion within the work cycle for a predetermined, earliest position of the individual combustion in the work cycle; (5) comparing the inverse efficiency factor facTrq2QDes with a maximum inverse efficiency factor facTrq2QMIMax at least one individual combustion, wherein the maximum inefficiency factor facTrq2QMIMax is determined from the inverse efficiency factor characteristic versus a center of gravity of the respective individual combustion within the work cycle for a predetermined latest location of the respective individual combustion in the work cycle; (6) determining the location of the respective individual combustion on the predetermined earliest possible value and determining a control angle and a drive amount for each individual combustion with earliest possible in the event that the inverse efficiency factor facTrq2QDes is less than the minimum inverse efficiency factor facTrq2QMIMin; (7) setting the location of each individual combustion at a value between the predetermined earliest position and the predetermined latest position of the respective individual combustion which in the inverse efficiency factor curve corresponds to the inverse efficiency factor facTrq2QDes, and determining a drive angle and a drive amount for the respective single combustion, in the case where the inefficiency factor facTrq2QDes is equal to or greater than the minimum inverse efficiency factor facTrq2QMIMin and equal to or less than the maximum inverse efficiency factor facTrq2QMIMax; (8) Defining the location of each individual combustion at the predetermined latest possible value in the work cycle and activating at least one post-combustion g, which has a predetermined position after each combustion in the duty cycle, and determining a drive angle and a drive amount for the respective individual combustion and afterburning, in the event that the target value for the inefficiency factor facTrq2QDes greater than the maximum inverse efficiency factor facTrq2QMIMax ,

Description

The invention relates to a method for operating an internal combustion engine, wherein in n working cylinders, where n = 1, 2,... Z, n is an integer and Z is a total number of working cylinders of the internal combustion engine, in each case one reciprocating piston executes successive working cycles and over one Each individual combustion of a duty cycle generates a total torque Trq and a total amount of heat Q, according to the preamble of claim 1.

During operation of an internal combustion engine in a motor vehicle, an injection of fuel into combustion chambers of working cylinders of the internal combustion engine is predetermined by the driver's request (actuation of the accelerator pedal) and possibly some corrections. If, in a certain operating state, such as, for example, a particulate filter regeneration, it is additionally necessary to increase the exhaust gas temperature, an additional post-injection is activated and further corrections are transferred from a temperature regulator to the injection. This leads to a large number of influenceable variables. These are determined at different points and thus lead to an unmanageable wealth of influencing functions.

From the DE 103 19 332 B3 is a method and a control device for limiting the amount of heat supplied to an internal combustion engine known. In order to achieve an optimization of the torque request, the heat quantity supply is monitored in the internal combustion engine by means of the control unit. The heat quantity supply is limited to a predetermined limit when the output from the engine actual torque is no longer increasing or the increase in the actual torque falls below a predetermined limit.

From the DE 100 46 446 A1 a method for controlling an internal combustion engine is known. In this case, a corresponding setpoint heat quantity is determined for a target torque to be performed, taking into account the instantaneous actual efficiency, to which at least one associated control variable is set in accordance with the value of the setpoint heat quantity. Furthermore, the actual amount of heat is detected, wherein a desired efficiency is determined from the actual amount of heat taking into account a work to be performed or a target torque to be provided. Then at least one manipulated variable of the internal combustion engine is adjusted in a timely manner corresponding to a setting of the determined target efficiency.

As a further prior art, the publications DE 10 2007 004 265 A1 . DE 10 2006 035 355 A1 and Pischinger R .: "Thermodynamics of the internal combustion engine", Vienna: Springer-Verlag, 1989, ISBN 3-211-82105-8, p.84 called.

The invention has for its object to provide a method of o.g. Art to improve that a more stable overall combustion is achieved.

This object is achieved by a method of o.g. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are described in the further claims.

• (1) Bestimmen eines Sollwertes für das Gesamtmoment TrqDes;
• (2) Bestimmen eines Sollwertes für die Gesamtwärmemenge QDes;
• (3) Bestimmen eines Sollwertes für einen inversen Wirkungsgradfaktor gemäß der Formel $$facTrq2QDes=\frac{QDes}{TrqDes};$$
  
• (4) Vergleichen des Sollwertes für den inversen Wirkungsgradfaktor facTrq2QDes mit einem minimalen inversen Wirkungsgradfaktor facTrq2QMIMin wenigstens einer Einzelverbrennung, wobei der minimale inverse Wirkungsgradfaktor facTrq2QMIMin aus einer Kennlinie für den inversen Wirkungsgradfaktor in Abhängigkeit von einer Schwerpunktlage der jeweiligen Einzelverbrennung innerhalb des Arbeitszyklus für eine vorbestimmte, früheste Lage der jeweiligen Einzelverbrennung im Arbeitszyklus bestimmt wird;
• (5) Vergleichen des Sollwertes für den inversen Wirkungsgradfaktor facTrq2QDes mit einem maximalen inversen Wirkungsgradfaktor facTrq2QMIMax wenigstens einer Einzelverbrennung, wobei der maximale inverse Wirkungsgradfaktor facTrq2QMIMax aus der Kennlinie für den inversen Wirkungsgradfaktor in Abhängigkeit von einer Schwerpunktlage der jeweiligen Einzelverbrennung innerhalb des Arbeitszyklus für eine vorbestimmte späteste Lage der jeweiligen Einzelverbrennung im Arbeitszyklus bestimmt wird;
• (6) Festlegen der Lage der jeweiligen Einzelverbrennung auf den vorbestimmten frühestens möglichen Wert sowie Bestimmen eines Ansteuerwinkels und einer Ansteuermenge für die jeweilige Einzelverbrennung mit frühester möglicher Lage, für den Fall, dass der Sollwert für den inversen Wirkungsgradfaktor facTrq2QDes kleiner als der minimale inverse Wirkungsgradfaktor facTrq2QMIMin ist;
• (7) Festlegen der Lage der jeweiligen Einzelverbrennung auf einen Wert zwischen der vorbestimmten, frühesten Lage und der vorbestimmten spätesten Lage der jeweiligen Einzelverbrennung, welcher in der Kennlinie für den inversen Wirkungsgradfaktor dem Sollwert für den inversen Wirkungsgradfaktor facTrq2QDes entspricht, sowie Bestimmen eines Ansteuerwinkels und einer Ansteuermenge für die jeweilige Einzelverbrennung, für den Fall, dass der Sollwert für den inversen Wirkungsgradfaktor facTrq2QDes gleich oder größer als der minimale inverse Wirkungsgradfaktor facTrq2QMIMin und gleich oder kleiner als der maximale inverse Wirkungsgradfaktor facTrq2QMIMax ist;
• (8) Festlegen der Lage der jeweiligen Einzelverbrennung auf den vorbestimmten spätestens möglichen Wert im Arbeitszyklus und Aktivieren wenigstens einer Nachverbrennung, welche im Arbeitszyklus eine vorbestimmte Lage nach der jeweiligen Einzelverbrennung aufweist, sowie Bestimmen eines Ansteuerwinkels und einer Ansteuermenge für die jeweilige Einzelverbrennung und für die Nachverbrennung, für den Fall, dass der Sollwert für den inversen Wirkungsgradfaktor facTrq2QDes größer als der maximale inverse Wirkungsgradfaktor facTrq2QMIMax ist.

For this purpose, it is provided according to the invention in a method of the aforementioned type that the following steps are carried out for each working cycle and each working cylinder,

• (1) determining a setpoint value for the total torque TrqDes;
• (2) determining a setpoint value for the total amount of heat Qdes;
• (3) determining a target value for an inverse efficiency factor according to the formula $$facTrq2QDes=\frac{QDes}{TrqDes};$$
  
• (4) comparing the inverse efficiency factor facTrq2QDes with a minimum inefficiency factor facTrq2QMIMin at least one individual combustion, the minimum inefficiency factor facTrq2QMIMin being an Inverse Efficiency Factor versus centroids of respective individual combustion within the duty cycle for a predetermined earliest one Location of each individual combustion in the work cycle is determined;
• (5) comparing the inverse efficiency factor facTrq2QDes with a maximum inverse efficiency factor facTrq2QMIMax of at least one single combustion, wherein the maximum inefficiency factor facTrq2QMIMax from the inverse efficiency factor curve versus a center of gravity of the respective individual combustion within the duty cycle for a predetermined latest location the individual combustion in the work cycle is determined;
• (6) setting the position of the respective individual combustion at the predetermined earliest possible value and determining a drive angle and a drive amount for each individual combustion with earliest possible position, in the event that the setpoint for the inefficiency factor facTrq2QDes less than the minimum inverse efficiency factor facTrq2QMIMin is;
• (7) setting the position of the respective individual combustion at a value between the predetermined earliest position and the predetermined latest position of the respective individual combustion which corresponds to the inverse efficiency factor setpoint facTrq2QDes in the inverse efficiency factor characteristic, and determining a drive angle and a Drive amount for the respective single combustion, in case the inverse efficiency factor facTrq2QDes is equal to or greater than the minimum inefficiency factor facTrq2QMIMin and equal to or smaller than the maximum inefficiency factor facTrq2QMIMax;
• (8) Setting the position of the respective individual combustion at the predetermined latest possible value in the work cycle and activating at least one afterburning, which has a predetermined position after each combustion in the work cycle, and determining a drive angle and a drive amount for the respective individual combustion and afterburning in the event that the inverse efficiency factor facTrq2QDes is greater than the maximum inverse efficiency factor facTrq2QMIMax.

This has the advantage that a combustion process can be predetermined by means of a physical interface based on torque and amount of heat, and a direct influence, for example, of a temperature regulator on a post-injection is resolved. The multiple control of the individual burns achieves a more stable overall combustion.

Conveniently, the individual combustion is a pre-combustion, a main combustion and / or a post-combustion.

The earliest and / or latest possible position of the individual combustion is preferably determined by the fact that this individual combustion still stably ignites.

die freigesetzte Wärmemenge Q auf die eingesetzte Kraftstoffmenge Qnt bezieht, wobei die Ansteuermenge für die Einzelverbrennung gemäß $$Qnt=QDes*facQ2Qnt$$

bestimmt wird.In a preferred embodiment, in step (6) and / or step (7) a factor facQ2Qnt is determined, which according to the formula $$facQ2Qnt=\frac{Qnt}{Q}$$

the amount of heat released Q refers to the amount of fuel used Qnt, wherein the driving amount for the individual combustion according to $$Qnt=QDes*facQ2Qnt$$

is determined.

$$facTrqPol=1-facTrqMI$$

bestimmt wird, wobei das von der Einzeleinspritzung erzeugte Moment TrqMI und das von der Nacheinspritzung erzeugte Moment TrqPol gemäß der Formeln $$TrqMI=TrqDes*facTrqMI$$

$$TrqPol=TrqDes*facTrqPol$$

bestimmt wird, wobei die von der Einzeleinspritzung erzeugte Wärmemenge QMI und die von der Nacheinspritzung erzeugte Wärmemenge QPol gemäß der Formeln $$QMI=TrqMI*facTrq2QMI$$

$$QPol=TrqPol*facTrq2QPol$$

berechnet wird, wobei ein Faktor facQ2Qnt bestimmt wird, welcher gemäß der Formel $$facQ2Qnt=\frac{Qnt}{Q}$$

die freigesetzte Wärmemenge Q auf die eingesetzte Kraftstoffmenge Qnt bezieht, wobei die Ansteuermenge für die Einzeleinspritzung QntMI und die Ansteuermenge für die Nacheinspritzung QntPol gemäß der Formeln $$QntMI=QMI*facQ2Qnt$$

$$QntPol=QPol*facQ2Qnt$$

berechnet wird.In a particularly preferred embodiment, in step (8), from the desired post-combustion position in the duty cycle by the inverse efficiency factor curve, a post-combustion inverse efficiency factor facTrq2QPol is determined, wherein a proportion factor of the single injection fraction of the total torque facTrqMI and a Proportion factor for the proportion of post-injection on the total moment facTrqPol according to the formulas $$facTrqMI=\frac{facTrq2QDes-facTrq2QPOl}{facTrq2QMIMax-facTrq2QPOl}$$

$$facTrqPOl=1-facTrqMI$$

wherein the torque TrqMI generated by the single injection and the torque TrqPol generated by the post-injection are determined according to the formulas $$TrqMI=TrqDes*facTrqMI$$

$$TrqPOl=TrqDes*facTrqPOl$$

is determined, wherein the amount of heat generated by the single injection QMI and the amount of heat generated by the post-injection QPol according to the formulas $$QMI=TrqMI*facTrq2QMI$$

$$QPOl=TrqPOl*facTrq2QPOl$$

is calculated, whereby a factor facQ2Qnt is determined, which according to the formula $$facQ2Qnt=\frac{Qnt}{Q}$$

the amount of heat released Q refers to the amount of fuel used Qnt, wherein the driving amount for the single injection QntMI and the Activation quantity for the post-injection QntPol according to the formulas $$QntMI=QMI*facQ2Qnt$$

$$QntPOl=QPOl*facQ2Qnt$$

is calculated.

In a preferred embodiment, at least one additional controller with a corresponding sensor for detecting an actual value is provided.

In a preferred embodiment, in step (1), the setpoint value for the total heat quantity Qdes is determined as a function of a temperature requirement and / or lambda requirement in conjunction with a gas filling and / or gas composition.

• 1 eine graphische Darstellung eines integralen Heizverlaufes eines Verbrennungsvorganges in einem Arbeitszylinder über einen Arbeitszyklus mit drei Einzelverbrennungen,
• 2 eine graphische Darstellung einer Kennlinie für einen inversen Wirkungsgradfaktor facTrq2Q = (Wärmemenge Q) / (Moment Trq) in Abhängigkeit von einer Schwerpunktlage der jeweiligen Einzelverbrennung innerhalb des Arbeitszyklus,
• 3 eine weitere graphische Darstellung der Kennlinie für den inversen Wirkungsgradfaktor facTrq2Q,
• 4 eine weitere graphische Darstellung der Kennlinie für den inversen Wirkungsgradfaktor facTrq2Q und
• 5 eine weitere graphische Darstellung der Kennlinie für den inversen Wirkungsgradfaktor facTrq2Q.

The invention will be explained in more detail below with reference to the drawing. This shows in

• 1 a graphical representation of an integral heating course of a combustion process in a working cylinder over a work cycle with three individual burns,
• 2 a graphical representation of a characteristic curve for an inverse efficiency factor facTrq2Q = (heat quantity Q) / (torque Trq) as a function of a center of gravity of the respective individual combustion within the work cycle,
• 3 a further graphical representation of the characteristic curve for the inverse efficiency factor facTrq2Q,
• 4 a further graphical representation of the characteristic curve for the inverse efficiency factor facTrq2Q and
• 5 a further graphical representation of the characteristic curve for the inverse efficiency factor facTrq2Q.

The present invention provides, in the broadest sense, a burnout former, as will be explained in detail below.

For a combustion process in a working cylinder of an internal combustion engine within a work cycle, in which a reciprocating piston in the working cylinder performs an intake stroke, a compression stroke, a power stroke and a Ausschubtakt is in 1 on a horizontal axis 10 a crank angle [° CA] and on a vertical axis 12 applied a quantity of heat [J]. A graph 14 illustrates a course of the amount of heat 12 over the crank angle 10 , At a crank angle of 0 ° KW is a top dead center (TDC) of the reciprocating piston in the power stroke. With 16 is an injection position of a pilot injection, with 18 is an injection position of a main injection, with 20 is an injection position of a post-injection, with 22 is a center of gravity of a pre-combustion (intermediate size), with 24 is a center of gravity of a main combustion (intermediate size), with 26 is a center of gravity of an afterburner (intermediate size), with 28 is a heat quantity of pre-combustion (intermediate size), with 30 is a heat quantity of the main combustion (intermediate size), with 32 is a heat quantity of the afterburning (intermediate size) and with 34 is a heat quantity of the total combustion of this one cycle, which serves as an input to the inventive method called.

In measurements, each individual combustion is first of all the amount of heat converted 12 and the torque value Trq assigned and linked to the center of gravity of the individual combustion. In a combustion with three individual events (individual burns with respective injection of fuel), as in 1 merely exemplified in the form of an integral heating curve for the three individual burns, a pre-injection takes place 16 with a fuel quantity Qnt of 2 mg at 15 ° crank angle before TDC, which results in a pre-combustion, wherein the pre-combustion heat release Q 28 of 50 J and a moment Trq of 10 Nm at a center of gravity 22 of 0 ° crank angle. Thereafter, a main injection takes place 18 with a fuel quantity Qnt of 7 mg at 5 ° crank angle to TDC, which results in a main combustion, the main combustion heat release Q 30 of 200 J and a moment Trq of 40 Nm at a center of gravity 24 of 13 ° crank angle to TDC. Thereafter, a post-injection takes place 20 with a fuel quantity Qnt of 10 mg at 40 ° crank angle after TDC, which results in afterburning, the afterburning resulting in heat release Q 32 of 250 J and a moment Trq of 20 Nm at a center of gravity 26 from 52 ° crank angle to TDC. The amounts of heat released Q 28 . 30 and 32 sum in total the amount of heat released Q 34 ,

From the measurements and evaluations of the individual burns, the released heat quantity Q and the generated torque Trq can now be assigned to the respective injection. If the quantity of heat Q is divided by the moment Trq of the individual injection and this is compared to the center of gravity of the individual combustion, a characteristic for an inverse efficiency factor facTrq2Q = (heat quantity Q) / (moment Trq) can be determined according to 2 create, with several measurements integrated. The inverse efficiency factor is defined as Quotient of heat quantity and moment. In 2 is on a horizontal axis 36 a center of gravity of the individual combustion plotted in [° KW] and on a vertical axis 38 the inverse efficiency facTrq2Q is plotted. At a crank angle of 0 ° KW is a top dead center (TDC) of the reciprocating piston in the power stroke. The registered individual points essentially result in a characteristic curve 40 for the inverse efficiency facTrq2Q about the center of gravity of combustion.

Concrete examples of in 2 registered points according to the above example of a combustion with three individual burns ( 1 ) are as follows: Pre-combustion: inverse efficiency factor facTrq2Q = 50J / 10 Nm = 5 gives the point (0; 5) in the coordinate system of 2 ; Main combustion: facTrq2Q = 200 J / 40 Nm = 5 gives the point (13; 5) in the coordinate system of 2 ; Afterburning: facTrq2Q = 250 J / 20 Nm = 12.5 gives the point (52; 12,5) in the coordinate system of 2 , For the inverse efficiency factor facTrq2Q, the result is as follows 2 can be seen, a characteristic curve 40 depending on the center of gravity of the individual combustion. This characteristic 40 is deposited for further determination in the Brennverlaufsformer.

The individual burns can not be moved freely in your position, as they either would not ignite or would result in a much lower gross emission result. For this reason, the individual burns can be specified only in certain areas. For the main combustion, for example, a range between 10 ° CA and 25 ° CA crank angle is specified after TDC. For this reason, multiple injections are necessary to be ignitable even in late individual combustion situations.

In order to match different injections so that a desired total torque and a desired total amount of heat are maintained, it is known to sometimes regulate different regulators against each other. For example, a temperature controller raises a post-injection quantity, whereby the torque controller subsequently reduces the main injection quantity due to an excessively high torque , However, this is disadvantageous because known influences should not be compensated by controllers. Controllers should instead be used for disturbances. In order to eliminate this, the method according to the invention is proposed which represents a combustion progression former.

The input variables of the method or this function of the Brennverlaufsformers are a target value of the total torque (TrqDes) and a target value of the total amount of heat (QDes). From these two values, a setpoint for the inverse efficiency factor (facTrq2QDes) is determined. This set point is compared with the inverse efficiency factor (facTrq2QMIMin) characterized by the early position of the main combustion, which is determined by means of the curve 40 is determined for the inverse efficiency factor (facTrq2Q), as in 3 is shown. In 3 are the same parts with the same reference numbers as in 2 so that their explanation to the above description of 2 is referenced. With 42 is an early location of the main combustion at 10 ° KW after OT and a line designates 44 indicates the inverse efficiency factor facTrq2QMIM in the early location of the main combustion. A dashed line 45 indicates the set point for the inverse factor facTrq2QDes.

As in the example according to 3 The setpoint facTrq2QDes may be smaller than facTrq2QMIMin. This means that in order to achieve the desired torque or the nominal value of the total torque TrqDes, it is necessary to release more heat than the requirement actually requires. It follows that the location of the main combustion on the early location 42 is held and as much heat is released as the desired torque TrqDes requires, as long as the maximum heat quantity limit is not exceeded. Thus, no afterburning is necessary in this case. This case occurs, for example, when the temperature controller has no requirement for the amount of heat and no deterioration of the efficiency is necessary. The limitation of the maximum amount of heat will be explained later.

If now more heat is to be generated at the same torque request, a deterioration in efficiency must take place. This means that the calculated target factor between total torque and total heat quantity (facTrq2QDes) is greater than the limit case of the early shift (facTrq2QMIMin). In addition to the early limit of the Hauptverbrennungslageverschiebung there is a late limit, which in turn with the help of the characteristic curve 40 of the inverse efficiency factor (facTrq2QMIMax) characterized by the late position of the main combustion provides a comparison value. In 4 this is shown, wherein like parts with the same reference numerals as in 3 so that their explanation to the above description of 3 is referenced. In addition is with 46 a late location of the main combustion at 18 ° CA after TDC and a line 48 denotes facTrq2QMIMax. A dashed line 50 denotes a value for the center of gravity of a single combustion, which is for the setpoint for the inverse Efficiency factor facTrq2QDes 45 due to the characteristic 40 would result.

Is the setpoint Trq2QDes, as in 4 shown exactly between the two limits facTrq2QMIMin and facTrq2QMIMax, the efficiency deterioration is achieved solely with the displacement of the main combustion. So it is still no afterburning needed. The position of the main combustion is again determined by the characteristic curve 40 the inverse efficiency factor formed by now the inverse efficiency factor 45 is given and the associated location 50 comes out. This occurs, for example, when the temperature requirement only wants to produce a slight increase in temperature compared to normal operation with the aid of the amount of heat.

$$facTrqPol=1-facTrqMI$$

If the heat quantity requirement continues to rise, the setpoint factor facTrq2QDes also increases 45 further and exceeds facTrq2QMIMax 48 for the late limit 46 the positional shift of the main combustion, as in 5 shown. In 5 are the same parts with the same reference numbers as in 4 so that their explanation to the above description of 4 is referenced. In addition features 52 a center of gravity of an afterburner and 54 one from the characteristic curve for the center of gravity 52 post-combustion inverse efficiency factor facTrq2QPol post-combustion. In this case, efficiency degradation can no longer be achieved by shifting the main combustion, because further retardation would cause the main injection to stop igniting and thus the main combustion would be lost. Therefore, the main combustion at this late location 46 held and activated an afterburner. Apart from one / more possibly present, small pre-injection has so far the main combustion produced almost the entire amount of heat and torque. Now, the division must be made so that both total momentum, as well as total amount of heat are met. Starting from the desired position 52 the afterburning is done with the help of the inverse efficiency curve 40 the inverse efficiency factor facTrq2QPol 54 the post-combustion determined. From the comparison of the three factors setpoint facTrq2QDes 45 with main combustion facTrq2QMIMax 48 and afterburning facTrq2QPol 54 it is determined how much of the total torque is to be generated by the main combustion (balancing the inverse efficiency factors). This is done according to the following equations: $$facTrqMI=\frac{facTrq2QDes-facTrq2QPOl}{facTrq2QMIMax-facTrq2QPOl}$$

$$facTrqPOl=1-facTrqMI$$

$$TrqPol=TrqDes*facTrqPol$$

If one multiplies the respective factor of the moment component facTrqMI of the main combustion or facTrqPol of the afterburning with the setpoint value of the total torque TrqDes, one obtains the respective torque value of the respective injection. The torque value of the main combustion (TrqMI) is equal to the setpoint value of the total torque (TrqDes) multiplied by the moment proportion of the main combustion (facTrqMI) or the torque value of the afterburning (TrqPol) is equal to the setpoint value of the total torque (TrqDes) multiplied by the moment proportion of the afterburning ( facTrqMI): $$TrqMI=TrqDes*facTrqMI$$

$$TrqPOl=TrqDes*facTrqPOl$$

$$QPol=TrqPol*facTrq2QPol$$

berechnet, wobei facTrq2QMI der inverse Wirkungsgradfaktor der Hauptverbrennung ist.The quantity of heat QMI generated by the main injection and the amount of heat QPol generated by the post-injection are then calculated according to the formulas $$QMI=TrqMI*facTrq2QMI$$

$$QPOl=TrqPOl*facTrq2QPOl$$

where facTrq2QMI is the inverse efficiency factor of the main combustion.

Thus, the torque components TrqMI, TrqPol, the individual heat quantities QMI, QPol and the layers are now 46 . 52 the individual burns known. Subsequently, the injection with respect to injection position and injection quantity is determined from this target combustion. Starting from an ignition delay, an injection position is calculated in each case for the main combustion and the post-combustion, which leads to the desired combustion events. In addition, a regulator is provided for the corresponding individual combustion, which adjusts the injection position in case of disturbances so that the combustion position is maintained.

In addition to the factor between moment and amount of heat, another factor is determined. This relates the amount of heat released Q to the amount of fuel used Qnt. $$facQ2Qnt=\frac{Qnt}{Q}$$

$$QntPol=QPol*facQ2Qnt$$

Using this factor, the injection quantity for the respective amount of heat for the main injection QntMI or for the post-injection QntPol determined according to the following formulas: $$QntMI=QMI*facQ2Qnt$$

$$QntPOl=QPOl*facQ2Qnt$$

Since different effects can lead to a fault, a regulator for the corresponding injection is also active here. This adjusts the injection quantity QntMl or QntPol in order to obtain the corresponding individual heat quantity QMI or QPol. Ultimately, one obtains the injection positions of the individual burns with the associated fuel quantities. Superimposed on the individual heat quantity controllers and position controllers, an overall torque controller is additionally provided, which if necessary corrects the setpoint value of the total torque TrqDes. For the aforementioned controller, a respective sensor is provided in each case, which supplies the respective actual size.

The heat quantity requirement Qdes described as input quantity represents a lower limit. In addition, there is an upper limit of heat quantity. Based on the upper heat quantity limit, a maximum torque is determined, which at the best adjustable efficiency does not exceed this upper limit. This is relevant, for example, in dynamics. If, for example, a temperature requirement leads to an increased heat quantity requirement and at the same time a high torque is required, the instantaneous demand would be dependent on the inertia of the air system (turbo lag), since the post injection with its poor efficiency continues to be involved in the temperature generation. Due to this structure and approach, the smoke limitation in the upper heat quantity limit would rise and determine a maximum moment. This moment could be represented immediately and one would immediately forego an efficiency-deteriorating post-injection. Thus, more momentum would be available at an earlier time. Until then, the air system should have provided the appropriate filling.

The comparison of the inverse efficiency factors does not necessarily have to be carried out this way; it can also be done with the aid of the characteristic curve 40 the desired position is determined and then compared with the position limits.

In the embodiment described by way of example only, two areas are divided into two, namely the main combustion, to which all pre-combustion are also counted, and the post-combustion, in which all burning after-burns are drawn together. The further procedure, however, involves the individual regulation of burns which burn separately. One example concerns several individually burning afterburns, which are also already integrated in this function. So there is more than just a main combustion and an afterburning possible.

With the method according to the invention, different errors and the associated reactions can be assessed. By the separation into individual burns and the distinction in the different regulators, for example, a change of fuel properties can be determined by the heat quantity regulator. In contrast, the cylinder-specific torque controller could detect errors in the high-pressure process. The multiple control of the individual burns achieves a more stable overall combustion.

By using the amount of heat, a direct fixed influence of the temperature controller is interrupted to a solid post-injection. Another temperature requirement, if it is to be caused by an increase in the amount of heat, can be achieved both by shifting the main combustion, and by activating / relocating an afterburner. This decision is left to the function of the Brennverlaufsformers. It does not matter whether the increased amount of heat comes from a temperature controller or is requested by a lambda controller or other sources. Both lambda and temperature can therefore only be considered with the combination of the air system (gas mass, gas composition). The same applies to the upper limit of heat. This was described as a kind of smoke limitation, but can also be determined by a maximum temperature.

The functionality of the Brennverlaufformers gets as input the moment and a total amount of heat. The moment is predetermined, for example, in a motor vehicle by a driver by the more or less strong operation of an accelerator pedal. The amount of heat is determined for example by the temperature requirement and / or Lambdaanforderung in connection with the gas filling. The output variables are control angles and injection quantities of the individual burning injections (individual burns). The combustion progression former determines individual burnings, which in total produce exactly the required setpoint values for torque TrqDes and heat quantity QDes. Serve for this purpose intermediate sizes for combustion situations of the individual burns, inverse efficiency factors of the individual burns, moment proportions of the individual burns, moment value of the individual burns and / or amounts of heat of the individual burns.

In order to pack more energy into the system, without the delivered torque increases, the deterioration of the efficiency by means of positional shift of the individual burns is provided. As a result, for example, the exhaust gas temperature is increased or regulated a lambda value. One known means is the retard shift of the combustion center posture and the activation of the post-combustion burning injection. These methods are currently used only on the basis of the known effect, without paying attention to physical backgrounds. This leads in particular to problems when several controllers intervene on different injections without being coordinated with each other. This problem is solved by a fixed interface in the form of Brennverlaufformers according to the inventive method.

LIST OF REFERENCE NUMBERS

10

horizontal axis: crank angle [° KW]

12

vertical axis: amount of heat [J]

14

Graph: Course of the heat quantity 12 over the crank angle 10

16

Injection position of a pilot injection

18

Injection position of a main injection

20

Injection position of a post-injection

22

Center of gravity of a pre-combustion (intermediate size)

24

Center of gravity of a main combustion (intermediate size)

26

Center of gravity of an afterburner (intermediate size)

28

Amount of heat of pre-combustion (intermediate size)

30

Heat quantity of the main combustion (intermediate size)

32

Amount of heat of afterburning (intermediate size)

34

Heat quantity of the entire combustion of a work cycle

36

horizontal axis: center of gravity of individual combustion in [° CA]

38

vertical axis: inverse efficiency facTrq2Q

40

Characteristic curve for the inverse efficiency factor facTrq2Q as a function of the center of gravity of the individual combustion

42

early location of the main combustion

44

Line: facTrq2QMIMin

45

dashed line: setpoint for the inverse factor facTrq2QDes

46

late location of the main combustion

48

Line: facTrq2QMIMax

50

Line: value for the center of gravity of a single combustion, which is calculated for the setpoint value for the inverse efficiency factor facTrq2QDes 45 due to the characteristic 40 would result

52

Center of gravity post-injection

54

inverse efficiency factor facTrq2QPol

Claims (8)

Method for operating an internal combustion engine, wherein in n working cylinders, where n = 1, 2,... Z, n is an integer and Z is a total number of working cylinders of the internal combustion engine, one reciprocating piston executes successive working cycles and at least one over a working cycle Performs single combustion, wherein all individual burns of a duty cycle produce a total torque Trq and a total heat quantity Q, characterized in that for each duty cycle and each working cylinder the following steps are performed: (1) determining a setpoint value for the total torque TrqDes; (2) determining a setpoint value for the total amount of heat Qdes; (3) determining a target value for an inverse efficiency factor according to the formula $$facTrq2QDes=\frac{QDes}{TrqDes};$$

(4) comparing the inverse efficiency factor facTrq2QDes with a minimum inefficiency factor facTrq2QMIMin at least one individual combustion, the minimum inefficiency factor facTrq2QMIMin being an Inverse Efficiency Factor versus centroids of respective individual combustion within the duty cycle for a predetermined earliest one Location of each individual combustion in the work cycle is determined; (5) comparing the setpoint value for the inverse efficiency factor facTrq2QDes with a maximum inverse efficiency factor facTrq2QMIMax of at least one individual combustion, wherein the maximum inverse efficiency factor facTrq2QMIMax from the inverse efficiency factor curve as a function of a center of gravity of the respective individual combustion within the Duty cycle is determined for a predetermined latest position of each individual combustion in the work cycle; (6) setting the position of the respective individual combustion at the predetermined earliest possible value and determining a drive angle and a drive amount for each individual combustion with earliest possible position, in the event that the setpoint for the inefficiency factor facTrq2QDes less than the minimum inverse efficiency factor facTrq2QMIMin is; (7) setting the position of the respective individual combustion at a value between the predetermined earliest position and the predetermined latest position of the respective individual combustion which corresponds to the inverse efficiency factor setpoint facTrq2QDes in the inverse efficiency factor characteristic, and determining a drive angle and a Drive amount for the respective single combustion, in case the inverse efficiency factor facTrq2QDes is equal to or greater than the minimum inefficiency factor facTrq2QMIMin and equal to or smaller than the maximum inefficiency factor facTrq2QMIMax; (8) Setting the position of the respective individual combustion at the predetermined latest possible value in the work cycle and activating at least one afterburning, which has a predetermined position after each combustion in the work cycle, and determining a drive angle and a drive amount for the respective individual combustion and afterburning in the event that the inverse efficiency factor facTrq2QDes is greater than the maximum inverse efficiency factor facTrq2QMIMax. Method according to Claim 1 , characterized in that the individual combustion is a pre-combustion, a main combustion and / or a post-combustion. Method according to at least one of the preceding claims, characterized in that the earliest position of the individual combustion is determined by the fact that this individual combustion still stably ignites. Method according to at least one of the preceding claims, characterized in that the latest position of the individual combustion is determined by the fact that this individual combustion still stably ignites. Method according to at least one of the preceding claims, characterized in that in step (6) and / or step (7) a factor facQ2Qnt is determined, which according to the formula $$facQ2Qnt=\frac{Qnt}{Q}$$

the amount of heat released Q refers to the amount of fuel used Qnt, wherein the driving amount for the individual combustion according to $$Qnt=QDes*facQ2Qnt$$

is determined. Method according to at least one of the preceding claims, characterized in that in step (8) a value for the inverse efficiency factor of afterburning facTrq2QPol is determined from the desired post-combustion position in the work cycle by means of the inverse efficiency factor characteristic curve, wherein a proportion factor for the proportion of Single injection on the total torque facTrqMI and a share factor for the proportion of post-injection on the total torque facTrqPol according to the formulas $$facTrqMI=\frac{facTrq2QDes-facTrq2QPOl}{facTrq2QMIMax-facTrq2QPOl}$$

$$facTrqPOl=1-facTrqMI$$

wherein the torque TrqMI generated by the single injection and the torque TrqPol generated by the post-injection are determined according to the formulas $$TrqMI=TrqDes*facTrqMI$$

$$TrqPOl=TrqDes*facTrqPOl$$

is determined, wherein the amount of heat generated by the single injection QMI and the amount of heat generated by the post-injection QPol according to the formulas $$QMI=TrqMI*facTrq2QMI$$

$$QPOl=TrqPOl*facTrq2QPOl$$

is calculated, whereby a factor facQ2Qnt is determined, which according to the formula $$facQ2Qnt=\frac{Qnt}{Q}$$

the amount of heat released Q refers to the amount of fuel used Qnt, the Single-injection control quantity QntMI and post-injection control quantity QntPol according to the formulas $$QntMI=QMI*facQ2Qnt$$

$$QntPOl=QPOl*facQ2Qnt$$

is calculated. Method according to at least one of the preceding claims, characterized in that at least one additional controller is provided with a corresponding sensor for detecting an actual value. Method according to at least one of the preceding claims, characterized in that in step (1) the setpoint value for the total amount of heat Qdes is determined as a function of a temperature requirement and / or lambda requirement in connection with a gas filling and / or gas composition.

Images