DE102006003601B3 - Internal combustion engine control variable determining method, involves computing actual control variable as sum of auxiliary control variable and product of actual factor and as difference of reference and another control variables - Google Patents

Abstract

The method involves determining actual value of a physical variable, and an auxiliary control variable. An actual factor and an instantaneous value of the physical variable are determined. An actual control variable is computed as a sum of another auxiliary control variable and a product of the actual factor and as a difference of a reference control variable and the former auxiliary control variable.

Description

The The invention relates to a method for determining one of four others physical size dependent control size Internal combustion engine online during the control and / or regulation of the internal combustion engine.

Around In modern internal combustion engines exhaust emissions and fuel consumption to reduce and in addition To increase the efficiency, more and more adjustment possibilities are created and used. To the adjustment possibilities belong for example the possibility the camshaft adjustment, the use of a variable intake manifold, the use of swirl flaps or exhaust gas recirculation. The from an engine control unit determined, central control variables for Influencing the operation of the internal combustion engine, such as ignition angle and injection time, are no longer just classical characteristics of the Operating state of the internal combustion engine, such as speed and load, dependent, but in addition also of characteristics of used in the internal combustion engine adjustment.

These Increase in physical dependencies led for the introduction a plurality of two- or three-dimensional maps, the for determining a tax quantity of a Run through internal combustion engine and their output variables in part complex way linked together become. Each of the maps must be checked in advance by test bench measurements, Trial runs and offline calculations are determined before it finally can be stored in a memory of the engine control unit. by virtue of The variety of maps is the effort to determine them and thus the effort to commission a new internal combustion engine clearly increased, because the multiple dependencies the control variables of the different parameters are not more readily to overlook are, which is why additional Application tools, for example so-called calibration programs must be used. This is particularly necessary if output variables of the Maps represent physical intermediate variables that no directly related to the taxable amount to be determined. This is the effort for map determination partially so high that a direct correction of the maps during the Trial rides almost impossible is.

In the DE 43 04 441 A1 is a method for determining the ignition angle in an internal combustion engine described, wherein the dependence of the ignition angle of the rotational speed as a first physical quantity and the load as a second physical quantity by three-dimensional maps is reproduced. Furthermore, two further physical quantities are taken into account in the calculation of a corrected ignition angle.

From the DE 102 57 994 A1 a method for Zündwinkelbestimmung is known, wherein by means of a three-dimensional map depending on the Dehzahl and the load a Grundzündwinkel is modeled and this is changed depending on further control variables of the internal combustion engine.

The DE 100 61 428 A1 describes a method for determining the ignition angle, in which case the intake and exhaust camshaft positions serve as model parameters.

task It is the object of the present invention to provide a method of determination one of four other physical quantities dependent control variable of the internal combustion engine specify the physical relationships between the sizes in manageable Way considered are.

These The object is achieved by a method according to claim 1.

The inventive method based on the fundamental idea, that normally the range of values of the four physical sizes up and is bounded below and thus defined at these boundaries Conditions exist. Accordingly, in the method according to the invention provided that the value ranges of a third and a fourth of the four physical quantities limits a respective initial value and a respective final value are. This results in a total of four two-dimensional boundary points, the four possible ones Combinations of start and end values correspond.

At each of these boundary points becomes an associated three-dimensional boundary map offline determines what the dependency the control size of one first and a second of the physical quantities and in which the third and fourth of the physical quantities in the determination of a limit map be recorded in the respective boundary point.

On the same way offline becomes a three-dimensional reference map the tax size over the first and second physical quantities determined, the third and the fourth physical quantity at each a predetermined reference value which is within the value ranges of the third and fourth physical quantities. Form the reference values of the third and fourth physical quantities a two-dimensional reference point.

In addition to the four border maps and the Reference map is needed as a further a three-dimensional factor map, which contains the course of a factor over the value ranges of the third and the fourth physical quantity, wherein the factor reflects the influence of the third and fourth physical quantity on the control variable. It is assumed that an intermediate value of the control variable is first determined as a function of two predefined values of the first and the second physical variable. The deviation of the control variable resulting from this intermediate value as a function of the third and the fourth physical variable is now mapped by the factor map.

The four limit maps, the reference map and the factor map be in advance in a memory unit of a control unit of the Internal combustion engine filed with them online, so during the Operating the internal combustion engine, the inventive method perform.

This begins with the determination of the current actual values of the four physical Sizes. With Help the first and second physical size becomes subsequently one of four limit control variables and one of four limit maps determined from the reference map a reference control variable.

The form four limit control variables along with their associated Boundary points the four vertices of one in three-dimensional space stretched surface. This area is referred to below as an auxiliary map.

With Help of the auxiliary map is over the reference values of the third and the fourth physical quantity one first auxiliary control size and over the Actual values of the third and the fourth physical quantity one second auxiliary control variable determined.

After that is calculated from the factor field and the actual values of the third and the fourth physical size of a current Factor determined. Subsequently a correction value is calculated by forming the product the current factor and the difference of the reference control variable and the first auxiliary control variable. With the correction value is taken into account, how the influence of the third and fourth physical magnitude with the Influence of the first and second physical quantities on the Control size superimposed.

Finally, it will the current tax size as a sum from the second auxiliary control variable and the Correction value calculated.

Of the Advantage of the method according to the invention is that the needed Boundary maps and the reference map as an output no intermediate sizes, but directly have to be determined control variable. The relationship between a change the first and / or the second physical variable and a resulting change the tax amount is thus directly recognizable. Conversely, the influence of a changed is also Tax size on the first and the second physical variable directly derivable, which is at the creation and correction of the maps in experimental operation advantageous is because there are no indirect dependencies exist between the maps and the easier manageability the connections reduced the effort for map adaptation.

The further dependencies the tax size of the third and fourth physical size are exclusively on the Factor map, where its output, the factor, again has a direct influence on the taxable amount, i.e. The relationships taken into account by this characteristic can also be explained good overview, what the final Definition of the map simplified.

Of the Effort to generate the factor map can be further reduced if its course is offline through a mathematical function it is determined that the actual physical relationship between the third and the fourth physical size and the Control size is approximated. In this way you have to not in the determination of the factor map for an internal combustion engine more the individual data points are determined separately, for example by individual measurements or individual calculations, but it suffices the knowledge the general expected course of the factor map. This is in particular necessary changes and adjustments of the Factor map advantageous because instead of correcting all the individual Data points only the comparatively few parameters of mathematical function must be adjusted.

In An embodiment of the invention is the course of the factor map offline determined by interpolation between a three-dimensional point, the reference values of the third and fourth physical quantities and a predetermined reference factor is assigned, and the three-dimensional Points corresponding to a respective combination of start and end values of the third and fourth physical size and one in each of four assigned limit factors are assigned

In In another embodiment, the reference values of the third and the fourth physical quantity chosen so that they each have the mean value of the value range of the third and the fourth physical quantity.

In an execution the method according to the invention the control variable sets the ignition angle an internal combustion engine. The first physical size is their speed, the second physical quantity of their air mass flow in Intake tract, the third physical quantity, the intake camshaft position and the fourth physical quantity is the exhaust camshaft position.

at this version the factor field is preferably determined by interpolation, where the reference factor is one and four limit factors in each case the value zero are given.

The Invention and its embodiments will be described below with reference to an embodiment and the drawing explained in more detail.

It demonstrate

1 schematic limit maps, a reference map and a view of a resulting auxiliary map;

2 a first possible course of a factor map;

3 a second possible course of a factor map;

4 a block diagram for determining a corrected ignition angle of speed, air mass flow, intake camshaft position and exhaust camshaft position;

5 the resulting auxiliary map 1 ;

6 a curve of the corrected ignition angle over the value ranges of intake and exhaust camshaft position.

The in the following described embodiment refers to an internal combustion engine, with the help of a control unit the control quantity ignition angle is determined. In the process, the dependencies of the ignition angle become Z of the first physical size speed N, the second physical Size air mass flow L, the third physical quantity intake camshaft position E and the fourth physical size exhaust camshaft position A considered. The air mass flow L is an indication of the on the internal combustion engine acting load.

The Intake camshaft position E may be values between an initial position Assume E0 and an end position E1 of the intake camshaft. Corresponding the value range of the exhaust camshaft position moves in between an initial position A0 and an end position A1 of the exhaust camshaft.

In 1 are four three-dimensional limit maps G1, G2, G3 and G4 respectively representing the dependence of the ignition angle Z - corresponding to Z1, Z2, Z3 and Z4 - of rotational speed N and air mass flow L, the limit map G1 for the initial position E0 and the Starting position A0 of the camshaft was recorded, the limit map G2 for the final position E1 and the initial position A0, the boundary map G3 for the initial position E0 and the end position A1 and the limit map G4 for the final position E1 and the end position A1. It is also in 1 to see a reference map R, which represents the dependence of the ignition angle ZR of rotational speed N and air mass flow L at reference positions ER and AR of the intake and the exhaust camshaft.

These five maps, G1 to G4 and R, correspond to the known maps for playback the dependence the ignition angle an engine of speed and load, i. they are without huge additional Overhead on a conventional test bench determined. Further additional calculations or special measurements, in which also the camshaft positions must be varied are not required to determine the maps. The five maps be in a memory unit of the control unit of the internal combustion engine stored.

In addition, in the controller one of the three-dimensional factor maps according to one of 2 or 3 stored, which represents a relationship between the intake camshaft position E, the exhaust camshaft position A and a factor F. The factor map is preliminarily determined by interpolation between the five predetermined points 1 to 5 determined, where the points are assigned the following values: point 1 = [E0, A0, 0]; Point 2 = [E1, A0, 0]; Point 3 = [E0, A1, 0]; Point 4 = [E1, A1, 0] and point 5 = [ER, AR, 1]. The reference values ER and AR are therefore a reference factor of the value one and the various combinations of start and end positions are each assigned a limit factor of zero. The interpolation is done according to 2 with the unit ball and according to 3 linear. However, the shape of the factor map can also be arbitrarily changed by the choice of another interpolation function and adapted to the behavior of the internal combustion engine.

With the maps G1 to G4 and R and the factor map is in normal operation of the internal combustion engine, ie online, the in 4 illustrated method executed. In this case, a current by means of a program running in the control unit to be set ignition angle Z_ist from the actual values of the rotational speed N_ist, the air mass flow L_ist, the intake camshaft position E_ist and the exhaust camshaft position A_ist determined.

About the Boundary maps G1 to G4 are from the actual speed N_ist and the actual air mass flow L_is the limit control variables ZG1 to ZG4 determined. In the same way you get from the actual speed N_act, the actual air mass flow L_act and the reference characteristic R the reference control quantity ZR_ist.

The four limit control variables ZG1 to ZG4, together with their respective intake and exhaust camshaft start and end positions, respectively, form the four vertices of an area in three-dimensional space as shown in FIG 5 is shown. This area is referred to as auxiliary map H. The four vertices have the following values: dot 6 = [E0, A0, ZG1]; Point 7 = [E1, A0, ZG2]; Point 8th = [E0, A1, ZG3] and point 9 [E1, A1, ZG4]. Schematically, this relationship is also in 1 shown where the four limit control variables ZG1 to ZG4 form the corners of a square.

Subsequently, a first auxiliary control variable ZHR is determined (see 4 ) whose value can be read from the auxiliary map H over the reference values ER and AR. The resulting point 10 in the auxiliary map H with the values [ER, AR, ZHR] is in 5 marked with.

Likewise, from the auxiliary map H, the value for a second auxiliary control variable ZH_ist is determined, namely the value above the actual values of intake and exhaust camshaft position, E_ist and A_ist. This leads to the point 11 according to 5 , with the values [E_ist, A_ist, ZH_ist].

However, since the relationship between the intake and exhaust camshaft positions E and A and the resulting ignition angle is not as linear as assumed by the auxiliary map H, the second auxiliary control amount ZH_act must still be corrected. This is done via the factor map, from which the factor F_act associated with the actual values of intake and exhaust camshaft position, E_act and A_act, is determined ( 4 ). The factor F_act is multiplied by the difference between the reference control quantity ZR and the first auxiliary control quantity ZHR, and the resulting correction value is added to the second auxiliary control quantity ZH_ist. The result of this correction is the actual ignition angle Z_act to be set.

In 6 is the course of the corrected ignition angle Z_ist over the value ranges of intake and exhaust camshaft position, E and A, see how it results in a fixed value pair of speed N and air mass flow L, if the factor map off 2 is used. Point 12 indicates the values associated with the reference control quantity ZR_ist [ER, AR, ZR_ist] and point 13 the values associated with the corrected ignition angle Z_act [E_act, A_act, Z_act].

Claims (6)

Method for determining a control variable (Z) of an internal combustion engine, which is dependent on four further physical variables (N, L, E, A), online during the control and / or regulation of the internal combustion engine, wherein - the value ranges of a third (E) and a fourth (A ) of the four physical quantities are delimited by a respective initial value (E0, A0) and a respective end value (E1, A1), - in a memory unit associated with the internal combustion engine, four three-dimensional limit characteristics (G1, G2, G3, G4) are stored, which contain a physical relationship between a first (N) and a second (L) of the four physical quantities and the control variable (Z) and in which the third (E) and the fourth (A) physical quantity each one of its beginning (E0, A0 ) and final values (E1, A1) occupy, - in the memory unit, a three-dimensional reference map (R) is stored, the physical relationship between the first (N) and the zw the third (E) and the fourth (A) physical quantities each occupy a fixed reference value (ER, AR) within their value ranges, - a three-dimensional one in the memory unit Factor map containing the progression of a factor (F) over the value ranges of the third (E) and fourth (A) physical quantities, where the factor (F) influences the third (E) and fourth (A) physical quantities to the control variable (Z), comprising the steps of - determining current actual values of the first (N_act), the second (L_act), the third (E_act) and the fourth (A_act) physical variable, - determination of four limit control variables ( ZG1, ZG2, ZG3, ZG4) from the four limit maps (G1, G2, G3, G4) and the actual values of the first (N_ist) and second (L_ist) physical quantities, - determination of a reference control variable (ZR_ist) from the reference map n field (R) and the actual values of the first (N_act) and the second (L_act) physical quantity, - determination of a first auxiliary control variable (ZHR) from a three-dimensional auxiliary map (H) and the reference values of the first (ER) and the second physical Size (AR), the auxiliary map (H) being made up of the points ([E0, A0, ZG1]; [E0, A1, ZG2]; [E1, A0, ZG3]; [E1, A1, ZG4]), which by the four limit control variables and the respective affiliated determination of a second auxiliary control variable (ZH_ist) from the auxiliary map (H) and the actual values of the third (E_ist) and the fourth (A_act) physical variable, - determination of a current factor (F ist) from the factor map and the actual values of the third (E_ist) and the fourth (A_act) physical quantity, - calculation of the current control variable (Z_act) as the sum of the second auxiliary control variable (ZH_act) and the product of current Factor (F_act) and the difference of the reference control variable (ZR_act) and the first auxiliary control variable (ZHR). Method according to claim 1, characterized in that that the course of the factor map offline through a mathematical Function is determined, which is related to the actual physical between the third (E) and the fourth (A) physical quantity and the Control variable (Z) is approximated. Method according to claim 2, characterized in that that the course of the factor map offline through interpolation is determined between a three-dimensional point, the reference values (ER, AR) and a predetermined reference factor is assigned, and the three-dimensional points of a particular combination from start and end values (E0, A0, E1, A0, E0, A1, E1, A1) and respectively are assigned to one of four predetermined limit factors. Method according to one of the preceding claims, characterized characterized in that the reference values of the third (ER) and the fourth (AR) physical quantity respectively the mean of the value range of the third (E) and the fourth (A) correspond to physical size. Method according to one of the preceding claims, characterized in that the control variable (Z) is the ignition angle of the internal combustion engine, the first physical quantity (N) is the Speed, the second physical quantity (L) the air mass flow, the third physical quantity (E) the Intake camshaft position and the fourth physical quantity (A) the Exhaust camshaft. Process according to Claims 3 and 5, characterized that as reference factor the value one and as four limit factors in each case the value zero are given.