WO2014111354A1

WO2014111354A1 - Method for operating an internal combustion engine, an inner cylinder pressure being ascertained in at least one cylinder of the internal combustion engine

Info

Publication number: WO2014111354A1
Application number: PCT/EP2014/050523
Authority: WO
Inventors: Vincenzo Rosito; Joachim Paul; Sebastian-Paul Wenzel
Original assignee: Robert Bosch Gmbh
Priority date: 2013-01-16
Filing date: 2014-01-14
Publication date: 2014-07-24
Also published as: DE102013200542A1

Abstract

The invention relates to a method for operating an internal combustion engine (100), an inner cylinder pressure (127) being ascertained in at least one cylinder (112) of the internal combustion engine (100). According to the invention, a maximum value (PZmax) is ascertained for the inner cylinder pressure (127) dependent on a rotational speed (133) and/or a rotational speed signal (136) of the internal combustion engine (100), an indexed medium pressure (602), a proportion (502) of a combusted fuel quantity, and a rotational angle (406) of a crankshaft (132).

Description

description

title

Method for operating an internal combustion engine, wherein a

Cylinder internal pressure is determined in at least one cylinder of the internal combustion engine

State of the art

The invention relates to a method according to the preamble of claim 1, and a control and / or regulating device, a computer program and a storage medium according to the independent claims.

In the operation of an internal combustion engine, it may be necessary to have a

Determine maximum value of a cylinder internal pressure in order to operate the internal combustion engine, if necessary, more precise. For example, this is done using one or more cylinder pressure sensors. However, it is often uneconomical to equip all cylinders of the internal combustion engine with it.

Disclosure of the invention

The problem underlying the invention is achieved by a method according to claim 1, as well as by a control and / or regulating device

Computer program and a storage medium after the siblings

Claims solved. Advantageous developments are specified in subclaims. Features which are important for the invention can also be found in the following description and in the drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again. The invention has the advantage that a maximum value for a

Cylinder internal pressure in a cylinder of an internal combustion engine below

Use of a speed and / or a speed signal of

Internal combustion engine, an indicated mean pressure, a share of

burned amount of fuel and a rotation angle of a crankshaft

("Crankshaft angle") can be determined comparatively simple, precise and inexpensive. This can be done with little effort by means of a control and / or regulating device for the internal combustion engine. Additional parameters characterizing the operation of the internal combustion engine need in the

Generally not be determined or measured. As a result, the operation of the internal combustion engine can be better monitored and / or controlled or regulated. The invention relates to a method for operating the internal combustion engine, wherein a cylinder internal pressure in at least one cylinder of

Internal combustion engine is determined. According to the invention, the maximum value for the cylinder internal pressure as a function of the rotational speed and / or the

Speed signal of the internal combustion engine, the indicated mean pressure, the proportion of the burned fuel quantity and the rotational angle of the crankshaft determined.

This dependence can be described by the following equation (1):

(1) PzMaxpZyl] = f (N, PMIpZyl], MFBxy% [iZyl], CA), where PzMax = maximum value of in-cylinder pressure;

f (...) = function;

N = rotational speed of the internal combustion engine in rpm (revolutions per minute);

PMI = indexed mean pressure (unit: bar);

MFBxy = fraction of fuel burned, where "xy" is a percentage; [iZyl] = index for the respective cylinder; and

CA = angle of rotation of the crankshaft.

According to the invention, the maximum value of the in-cylinder pressure is preferably determined using equation (1) in an indirect manner, that is to say without it being necessary to provide a cylinder on each cylinder of the internal combustion engine

To arrange cylinder pressure sensor. The indicated mean pressure (PMI) and the proportion The burned fuel quantity (MFBxy) - which are both input variables of the equation (1) - can be determined according to the method by means of two variants, as will be described below. By determining the crankshaft angle CA, the combustion process in the respective cylinder can be specifically evaluated.

Preferably, at least one cylinder of the internal combustion engine is designed as a so-called "guide cylinder". The master cylinder has a

Cylinder pressure sensor, with which a time course of the cylinder internal pressure can be determined in the master cylinder. However, the method can also be carried out without the use of the guide cylinder or the cylinder pressure sensor, see the "Variant 1" described below. Furthermore, that can

Speed signal can be used for the method by a time course of the speed signal and / or an average value of the speed signal and / or an acceleration of the speed or even higher time derivatives of the speed or the speed signal can be used.

The inventive method can, for example, for a

pressure-controlled operation (CPP, "cylinder pressure processing") of the internal combustion engine are used, wherein a time course and / or characteristic values of the cylinder internal pressure can be determined and used for a particularly precise control and / or regulation of the internal combustion engine. To simplify matters, the method according to the invention can also be described as follows: Depending on whether combustion of the fuel injected into the cylinder takes place comparatively "hard" or "softly", a predeterminable proportion of the fuel quantity is already at a comparatively small or only at a comparatively low level burned large crankshaft angle.

Accordingly, the maximum value of the in-cylinder pressure is comparatively high or comparatively low. Using the associated indicated mean pressure as well as the rotational speed and / or the rotational speed signal, this maximum value can be quantified according to the invention. Furthermore, it can be provided according to the invention that the described

Dependency for a respective type of internal combustion engine or for a respective design of the cylinder is determined in a pre-trial. This is preferably done using equation (1). During a so-called "application" or in a calibration operation or test mode of the internal combustion engine, the respective quantities can be measured or determined. This is done in particular on a test bench of a manufacturer of the internal combustion engine. The

Internal combustion engine is for example a diesel engine or a gasoline engine of a motor vehicle. The thus determined dependence can - using the determined variables - permanently in a data store for the

Internal combustion engine to be stored. In a subsequent normal operation of the internal combustion engine or of the motor vehicle, the

stored data are read and processed according to the invention and thus used for the control and / or regulation of the internal combustion engine, whereby the operation of the internal combustion engine can be improved. In one embodiment of the invention, the dependency is determined by means of a data-based modeling, in particular using an ASCMO model. The ASCMO model enables a particularly precise implementation of the method using a large number of variables characterizing the operation of the internal combustion engine. The term "ASCMO" includes generation of a global model that includes a plurality of

Variables and / or sizes and their respective relationships or correlations to operate the internal combustion engine in a variety of operating conditions. This makes it possible to obtain a mathematical model which includes or generates the above-described equation (1). In addition, it can be provided that the said global model and / or the equation

(1) be supplemented by one or more parameters such as a temperature, an air pressure, a fuel grade and the like.

The process of fuel combustion ("combustion") in the

Internal combustion engine generates a pressure increase in the respective cylinder. When

As a result, a torque is generated at the crankshaft by means of mechanical components, whereby a rotational movement of the crankshaft is accelerated. This results in a relationship between on the one hand thermodynamic and / or mechanical variables, and on the other hand, the combustion in the respective cylinder characterizing quantities. In a first variant of the method, the indicated mean pressure and / or the fraction of the burned fuel quantity is determined individually for each cylinder by means of a polytropic relationship as a function of a boost pressure and as a function of a time profile of the engine speed signal. For this purpose, a determination of the cylinder internal pressure in the guide cylinder is not required, which costs and costs can be saved. In general, a polytropic process can be described as a thermodynamic process, which is described, for example, by the following well-known equation (2):

(2) p * V ⁿ = C, where in an internal combustion engine p = in-cylinder pressure ("pumping pressure");

V = actual volume of the cylinder determined by a piston; n = polytropic index; and

C = constant.

By means of equation (2), a thermodynamic process involving compression and / or expansion of gas can be described in detail. The pumping pressure p is determined by the equation (2) using the

Cylinder volume V and with respect to the boost pressure in the absence of a combustion process determined. The pumping pressure p and the current

Cylinder volume V are both dynamic quantities. A deviation of the measured in-cylinder pressure with respect to the pumping pressure p calculated by means of equation (2) can thus be attributed to combustion processes in the respective cylinder. By means of an evaluation of the

Speed signal, the associated indicated mean pressure and the current proportion of the burned fuel quantity can be determined from it. These quantities can then be used as inputs in equation (1). The advantage here is that the pump pressure p or the cylinder internal pressure is determined instead of being measured using the cylinder pressure sensor. As a result, effort and costs can be reduced. This first variant will be explained in more detail below by means of Figure 3.

In a second variant of the method, the indicated mean pressure and / or the proportion of the burned fuel quantity is dependent on a time course of the Cylinder internal pressure in a guide cylinder of the internal combustion engine and determined depending on a time course of the speed signal of the internal combustion engine. The thus determined indexed mean pressure and / or the determined proportion of the burned fuel quantity is used to close the indicated mean pressure and / or the proportion of the burned fuel quantity in the other cylinders of the internal combustion engine. It can the current

Cylinder internal pressure in the guide cylinder by means of the cylinder pressure sensor determined comparatively accurate and thus the indicated mean pressure and the proportion of the burned fuel quantity for the guide cylinder as input variables in the equation (1) can be used. For the remaining cylinders, which have no cylinder pressure sensor, the respective in-cylinder pressure can be derived from the in-cylinder pressure of the guide cylinder using the speed signal. From the respective cylinder internal pressure can then also for the remaining cylinders of the indicated mean pressure and the proportion of the burned fuel quantity determined and used as input to the equation (1). This second variant is generally more accurate with respect to the first variant described above and will be explained in more detail below by means of Figure 4.

In a further embodiment of the method, the dependence between the maximum value for the in-cylinder pressure, the indicated mean pressure, the proportion of the burned fuel quantity and the rotational angle of the crankshaft is determined, wherein the dependence is corrected by means of a function dependent on the rotational speed of the crankshaft. This gives a simplified representation of equation (1), which can be described by the following equation (3):

(3) PzMax = f (PMI, MFBxy%, CA) ^* g (N), where

PzMax = maximum value of the in-cylinder pressure;

f (...) = function corresponding to a first factor in equation (3); g (...) = function corresponding to a second factor in equation (3);

N = speed of the crankshaft;

PMI = indexed mean pressure;

MFBxy = proportion (percentage) of the quantity of fuel burned; and

CA = angle of rotation of the crankshaft. In this way, the task of equation (1), namely mapping four independent quantities to a dependent quantity, is simplified by mapping only three independent quantities to the dependent size and using the fourth independent size only for a correction function.

Preferably, the correction function is formed such that an accuracy corresponding to equation (1) results.

The second equation g (N) represents a correction factor for the first function f (...) As a function of the rotational speed N. As a result, it is possible to reduce a total number of calculations, as a result of which costs can be saved. For example, the functions f (...) And / or g (N) can be implemented by means of models and / or characteristic diagrams and / or tables and the like.

As a result, so to speak, a "surface shape" for the maximum value of the cylinder internal pressure is defined. This surface shape is dependent on the speed of the internal combustion engine and can therefore be corrected by means of the correction factor or by means of the function g (N).

In a further embodiment of the method, the dependence between the maximum value for the cylinder internal pressure, the indicated mean pressure, the fraction of the burned fuel quantity and the rotational angle of the crankshaft is determined, wherein the dependence is parameterized by means of the rotational speed of the crankshaft. As a result, it is possible, as described above, to map only three independent quantities to a dependent variable and to use the fourth independent variable as a parameter. This can be described by the following equation (4):

PzMax = f (PMI, MFBxy%, CA) / N, where PzMax = maximum value of in-cylinder pressure;

f (...) = function;

PMI = indexed mean pressure;

MFBxy = percentage of burned fuel quantity;

CA = angle of rotation of the crankshaft; and

/ N = Parameterization of the function f (...) with values of the speed N

the internal combustion engine in each case suitable gradation. This also results in a simplification of the method according to the invention, whereby a corresponding effort in the calculations and thus costs can be reduced.

In a further embodiment of the method, the maximum value for the cylinder internal pressure using at least one polynomial function and / or at least one characteristic field as a function of the rotational speed and / or the rotational speed signal, the indicated mean pressure, the proportion of the burned fuel quantity and the rotational angle of the crankshaft determined. This can be done, for example, using equation (1), where the function f (...) is performed using the at least one polynomial function. Preferably, the respective coefficients of this polynomial function are determined in advance. This can be done for example by means of a so-called MATLAB software (registered trademark) or the like. Thereafter, the determined polynomial coefficients can be stored in the data memory of the control and / or regulating device. The optional use of the polynomial function - compared to large data tables - can reduce the amount of data to be stored. By the optional use of one or more maps, the dependency can be described particularly simply and accurately. This can result in lower costs as a whole.

In a further embodiment of the method, the dependence between the maximum value for the cylinder internal pressure, the rotational speed and / or the rotational speed signal, the indicated mean pressure, the proportion of the burned fuel quantity and the rotational angle of the crankshaft is determined in a first step by means of a neural network. For example, this is done under

Use of correlations between the respective sizes. In a second step, by means of the neural network, the maximum value for the

Cylinder internal pressure determined using the determined dependence. For example, the neural network is capable of determining and / or calculating and / or exchanging and / or processing and / or correlating a comparatively large number of variables. These quantities are for example sensors or signals or components or

Conditions of the internal combustion engine traceable. This can do that inventive method further simplified and cheapened. The said first step is preferably carried out in a so-called

"Application phase" on a suitably equipped with sensors and the like internal combustion engine. The said second step takes place

preferably on a standard running internal combustion engine during normal operation, for example in a motor vehicle.

In addition thereto, it can be provided that the dependence by means of the neural network in the first step using at least one other an operating state of the internal combustion engine

characterizing size is determined, wherein in the second step, the at least one other variable is taken into account accordingly. Depending on the correlations determined in the first step, it may even be possible that a direct determination of the indicated mean pressure and / or the proportion of the burned fuel quantity (in the second step) is not required.

The inventive method is particularly simple and accurate by means of a control and / or regulating device for the internal combustion engine feasible. This is preferably done using a computer program which is stored in the data memory of the control and / or regulating device or in another storage medium.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show:

Figure 1 is a simplified diagram of an internal combustion engine and a control and / or regulating device;

FIG. 2 shows a flowchart for operating the internal combustion engine according to FIG. 1;

FIG. 3 shows a block diagram for a method for operating the

Internal combustion engine;

Figure 4 shows three diagrams with an in-cylinder pressure in a cylinder, a cylinder internal pressure in all cylinders and a speed signal of the internal combustion engine over a crankshaft angle; Figure 5 is a diagram with a proportion of a quantity of fuel burned above the crankshaft angle;

FIG. 6 shows a three-dimensional diagram with a first value of a rotational speed as parameter;

FIG. 7 shows a three-dimensional diagram with a second value of the rotational speed as parameter;

FIG. 8 shows a three-dimensional diagram with a third value of the rotational speed as parameter;

Figure 9 is a three-dimensional diagram with a fourth value of the speed as a parameter;

FIG. 10 shows a three-dimensional diagram with a fifth value of the rotational speed as parameter;

FIG. 11 shows a first flow chart for the method for operating the

Internal combustion engine; and

FIG. 12 shows a second flow chart for the method for operating the

Internal combustion engine.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

The FIGS. 1 and 3 to 12 described below show, by way of example, the method according to the invention. FIG. 2 shows a preferred application for a determined maximum value for the in-cylinder pressure.

FIG. 1 shows a simplified diagram of an internal combustion engine 100, which in the present case has four cylinders 12a, 12b, 12c and 112d. The

Internal combustion engine 100 also has an intake tract 1 14 for the supply Fresh air or an air / fuel mixture and an exhaust tract 1 16 on.

In the intake tract 1 14 is a pressure sensor 1 18 ("boost pressure sensor")

arranged, which determine a boost pressure P22 of the fresh gas in the intake tract 1 14 and can forward a signal characterizing the boost pressure P22 to a control and / or regulating device 120 for the internal combustion engine 100. The control and / or regulating device 120 comprises a data memory 124 ("storage medium") as well as a data memory 124 stored in the

Computer program 122. Furthermore, at the exhaust tract 1 16 a

Exhaust gas temperature sensor 126 is arranged, which can determine an exhaust gas temperature T3 in the exhaust gas tract 1 16 and can transmit a signal characterizing the exhaust gas temperature T3 to the control and / or regulating device 120. Alternatively or in addition to the exhaust gas temperature sensor 126 may also be

Calculation model can be used, which determines the exhaust gas temperature T3 as a function of operating variables of the internal combustion engine 100. This takes place, for example, as a function of an amount of fresh air and / or the

Boost pressure P22 and / or the temperature T22 in the intake tract 1 14 of the internal combustion engine 100th

The cylinder 1 12a is presently designed as a so-called "master cylinder", wherein a cylinder internal pressure 127 is determined by means of a arranged on the cylinder 1 12a cylinder pressure sensor 128. A signal 130 characterizing the cylinder internal pressure 127 is sent to the control and / or regulating device

120 transmitted. In addition, several more signals between

Facilities of the internal combustion engine 100 and the control and / or

Control device 120 transmitted. This is indicated in FIG. 1 by a double arrow 131.

The internal combustion engine 100 may be self-igniting ("diesel engine") or else spark ignited ("gasoline engine"). In particular, the internal combustion engine 100 may also be associated with a device for charging the internal combustion engine 100, in particular a turbocharger (not shown). However, this is not mandatory for the function of the invention described below. During operation of the internal combustion engine 100, the cylinders 1 12 generate

Combustion of a fuel-air mixture generates a torque 138 on a crankshaft 132. The torque 138 characterizes a torque produced at the center of combustion (CoC, "Center of Combustion"). A rotational speed 133 of the crankshaft 132 can be determined by means of a sender wheel 134, wherein a rotational angle 406 (see FIG. 4) and a rotational speed signal 136 are transmitted to the control and / or regulating device 120. Further elements of the internal combustion engine 100, such as injectors, actuators and the like are not shown in the figure 1. Further details for operating the internal combustion engine 100 will be explained in more detail in the following figures 2 to 12.

FIG. 2 shows a flowchart for operating the internal combustion engine 100 in a preferred application. In a start block 196 in an upper portion of the drawing, the illustrated procedure begins. In a following block 198, a plurality of variables and / or parameters, such as an upper threshold value PZa for the in-cylinder pressure 127, an upper threshold value T3w for the exhaust gas temperature T3 in the exhaust tract 1 16, upper threshold values T22max and P22max for a temperature T22 and the boost pressure P22 in the intake tract 1 14, as well as a threshold value 242 ("APmaxCyl") for a permissible scattering range of maximum values PZmax of the cylinder internal pressure 127 in the cylinders 1 12a to 12d, predetermined or determined. Preferably, at least some of the aforementioned threshold values PZa, T3w, T22max, P22max and / or the

Threshold 242 of a current operating state ("operating point") of the internal combustion engine 100 dependent. The threshold value PZa corresponds to an "allowed" maximum value for the maximum value PZmax of the in-cylinder pressure 127.

In a following block 200, the respective maximum value PZmax of the in-cylinder pressure 127 in the cylinders 1 12a to 1 12d, as well as the

Exhaust gas temperature T3, the temperature T22 and the boost pressure P22 in the intake tract 1 14 determined. The block 200 is also a starting point for a respective cycle (cycle) of corresponding method steps, which can be carried out for each of the cylinders 1 12 individually or for all cylinders 1 12 together. In a following query block 240 can for at least two cylinders 1 12 of the internal combustion engine 100, but preferably for all four cylinders 1 12 of the internal combustion engine 100, each one of the cylinder internal pressure 127 in the respective cylinder 1 12 characterizing size, in particular a

Maximum value PZmax of the cylinder internal pressure 127 of the respective cylinder 1 12, are determined. The determination of the maximum value PZmax will be explained in more detail below with reference to FIGS. 3 to 12. The query block 240 is optional and therefore only shown in dashed lines in FIG. By means of the query block 240, a following can be allowed

Query block 210 and subsequent process branches 220 and 230 will only be traversed if the respective deviation of the maximum values PZmax the cylinder internal pressure 127 of the cylinder 1 12 with each other is not greater than the predetermined threshold 242. Otherwise, a branch is made to subsequent blocks 2410 and 2420, which can limit an error risk or an operating risk of the internal combustion engine 100.

From the different maximum values PZmax the cylinder 1 12 can in the

Query block 240 a measure of the deviation of these maximum values PZmax be formed among each other. This can be done, for example, by subtracting the maximum values PZmax for each cylinder 12 from each other, possibly with subsequent absolute value formation of the difference obtained in order to identify those two cylinders 12 of the internal combustion engine 100 whose maximum values PZmax have the greatest difference from one another. These

Difference is evaluated in the query block 240.

If, according to the check in query block 240, the greatest difference of these maximum values PZmax, ie a deviation of the maximum values PZmax of the relevant cylinders 1 12, exceeds the predefinable threshold value 242, the method branches to the following blocks 2410 and 2420.

In block 2410, the maximum torque 138 to be output by the internal combustion engine 100 is limited, for example by means of a so-called

"Torque coordinator". In the following block 2420, another diagnostic function can be executed, for example, a

Error memory entry in a fault memory of the control and / or Control device 120 (Figure 2) causes and / or has a signaling of a need for maintenance of the internal combustion engine 100 to the object. This is done, for example, acoustically and / or optically to a user of

Internal combustion engine 100 or to a driver of a motor vehicle driven by the internal combustion engine 100.

However, if, according to the check in query block 240, the deviation of the maximum values PZmax of the respective cylinders 1 12 from one another does not exceed the predefinable threshold value 242, a branch is made into the following query block 210.

In the query block 210, the maximum value PZmax of the in-cylinder pressure 127 is compared with the threshold value PZa for the respective cylinder 12. This query is in the present case by those listed in the query block 210

Inequality PZmax> PZa symbolizes. Depending on whether the maximum value PZmax the cylinder internal pressure 127 in the respective cylinder 1 12 is greater than the predetermined threshold PZa or not, then branched into one of the process branches 220 or 230, each one - largely different - influencing the further operation of the internal combustion engine 100 result.

If, for example, it has been determined for the cylinder under consideration 12 in the query block 210 that its maximum value PZmax is less than or equal to the predefinable threshold value PZa, a branch is made into the method branch 220. This is shown by a dashed border in a right-hand area of the drawing.

In a first query block 2210 of the method branch 220, a check is made as to whether the exhaust gas temperature T3 of the internal combustion engine 100 is greater than the threshold value T3w. The threshold T3w is preferably in

Dependent on an operating point of the internal combustion engine 100 given, for example, in the same manner as the operating point dependent selected threshold PZa the cylinder internal pressure 127th

If the check in the inquiry block 2210 shows that the exhaust gas temperature T3 is greater than the threshold value T3w, a branch is made into a block 2212 which provides a shift of an injection timing of the internal combustion engine 100 early to counteract the excessive exhaust gas temperature T3. Thereafter, the process branches again into the block 200 and starts, for example, with a new cycle for the same cylinder 1 12 or another cylinder 1 12.

However, if the check in the query block 2210 shows that the exhaust temperature T3 is less than or equal to the threshold T3w, a branch is made to a subsequent query block 2220. In the query block 2220 it is checked whether a driver's desired torque PWG - corresponding to a value between 0% and 100% - exceeds a predetermined threshold PWG1 or not. The threshold value PWG1 can be selected, for example, at approximately 100% or at least approximately 90% of a maximum possible driver request torque PWG. The driver's desired torque PWG is preferably determined by means of an accelerator pedal transmitter (not shown), which is connected to the control and / or

Control device 120 (Figure 1) is connected.

If the check in the query block 2220 according to FIG. 2 shows, for example, that the driver command torque PWG is smaller than the threshold value PWG1, the method according to FIG. 2 branches again to the block 200 for a new pass. However, if the check in query block 2220 shows that the current driver request torque PWG is greater than that

Threshold PWG1, it is branched into further query steps 2230 and 2240. In this case, the query block 2220 is then only in the

subsequent polling steps 2230 and 2240 branches if the current driver's desired torque PWG assumes relatively large values because the driver of the motor vehicle driven by the internal combustion engine 100 requests a correspondingly high torque 138.

In the interrogation step 2230, it is checked whether or not the temperature T22 in the intake tract 14 (FIG. 1) of the internal combustion engine 100 exceeds the upper threshold value T22max. Furthermore, it is checked in the interrogation step 2240 whether the boost pressure P22 in the intake tract 1 14 of the internal combustion engine 100 exceeds the threshold value P22max or not. If neither the temperature T22 If the boost pressure P22 still exceeds the respective threshold values T22max and P22max, then branching is made to the following block 2250.

In block 2250, an associated with the respective cylinder 1 12

fuel quantity to be injected increased. This is possible in the present case, since the

Temperatures T3 and T22 in the exhaust tract 1 16 and the intake tract 1 14 are below the associated thresholds T3w and T22max and the

Boost pressure P22 in the intake tract 1 14 is also below the associated threshold P22max. Therefore, with regard to these operating variables of the internal combustion engine 100, there are still reserves for higher temperatures T3 and T22 or for the boost pressure P22.

Furthermore, it has been checked in the inquiry block 2220 - as already described above - whether a relatively large driver request torque PWG> PWG1 has been requested. In this case, therefore, in block 2250, the

to be injected fuel quantity of the respective cylinder 1 12 increased by a predetermined amount to an increased torque 138 of the

Internal combustion engine 100 to effect. In this way, the injection quantity of the internal combustion engine 100 can also be increased beyond the amount predefined statically, for example by a characteristic diagram, provided that the corresponding operating variables T3, T22 and P22 of the internal combustion engine 100 are not already their respective predefinable

Thresholds T3w, T22max and P22max have exceeded. This means that when the temperatures T3 and T22 in the exhaust tract 1 16 and in the intake tract 14 and the boost pressure P22 in the intake tract 14 have not already exceeded the associated threshold values T3w, T22max and P22max and at the same time the driver has a particular high torque 138 requests, in block 2250 the injection quantity can be increased. This is possible in particular beyond the statically predetermined maximum dimension in a conventional system, so that the internal combustion engine 100 actually also outputs the driver-requested higher torque 138. After block 2250, the process branches again to block 200 of the method. However, if it is determined in query steps 2230 or 2240 that the

Temperature T22 and the boost pressure P22 in the intake tract 1 14 the associated with thresholds T22max and P22max, respectively, the increase in the injection quantity described above at block 2250 is not performed, but in turn, branching is made to block 200 for a re-run.

The above-described steps of the method branch 220 can be carried out for a cylinder 1 12 of the internal combustion engine 100, for a plurality of cylinders or for all cylinders 1 12 of the internal combustion engine 100. This can either be sequential or concurrently overlapping and e.g. synchronized with a respective duty cycle of the cylinder 1 12 considered.

In the presence of sufficient reserves with regard to the current

Temperature values or pressure values in the intake tract 1 14 or in the

Exhaust tract 1 16 can use the method branch 220 in the present embodiment, an individual elevation of the injected

Fuel quantity per cylinder 1 12 are made, if in addition the maximum value PZmax the cylinder internal pressure 127 is not already above the threshold PZa, see the review described in the

Query block 210.

However, if it has been determined in the query block 210 for a cylinder 1 12 under consideration that the maximum value PZmax is greater than or equal to the threshold value PZa, branching is made to the method branch 230 with the steps explained in more detail below. Process branch 230 is represented by a dashed border in a left-hand portion of the drawing of FIG.

In general, it should be noted that the predefinable threshold value PZa, which is used in the comparison of the query block 210, is preferably the same for all cylinders 1 12 of the internal combustion engine 100. Alternatively, he can, however, for

different cylinders 1 12 of the engine 100 are selected differently. In a first query block 2310 of the process branch 230 - comparable to the query block 2210 - the exhaust gas temperature T3 of the internal combustion engine 100 compared with the threshold T3w. In this case, the threshold value T3w in the query block 2310 may be selected to be the same or deviating from the corresponding threshold value T3w of the query block 2210. if the

Exhaust gas temperature T3 is greater than the threshold T3w, then it is branched to a block 2360, in which the fuel quantity to be injected for the cylinder in question 1 12 is reduced. After block 2360, the system branches back to block 200.

If, however, the exhaust gas temperature T3 is below the threshold value T3w, then a branch is made into an inquiry block 2320, in which, comparable to that

Query block 2220, the driver's desired torque PWG is compared with the threshold PWG1. In this case, the threshold value PWG1 in the query block 2320 may be selected to be the same or deviating from the corresponding threshold value PWG1 of the query block 2220. If the driver's desired torque PWG is greater than the threshold value PWG1, a branch is made in a block 2330, in which an injection time or an ignition point of time

Internal combustion engine 100 is retarded. After block 2330, the system branches back to block 200. However, if the driver's desired torque PWG is smaller than the threshold value

PWG1, then a block 2340 is branched, in which a diagnostic function is executed. This diagnostic function is preferably used to check the pressure sensor 1 18 ("boost pressure sensor") and / or - if available - for checking at least one actuator of a device for charging the internal combustion engine 100, such as a turbocharger (not shown).

Subsequently, in a block 2350, the maximum of the

Internal combustion engine 100 to be delivered torque 138 limited. This is done, for example, by means of a signaling of a maximum permissible

Torque 138 to the torque coordinator (not shown) of

Internal combustion engine 100. The torque coordinator can be implemented, for example, in the form of a software function in the computer program 122 of the control and / or regulating device 120 of the internal combustion engine 100. Likewise, any other parts and / or embodiments of the method for operating the internal combustion engine 100 according to FIG. 2 can be carried out completely or partially by means of the computer program 122. FIG. 3 shows a block diagram 300 with blocks or method steps for operating the internal combustion engine 100. A respective signal flow or a respective sequence of method steps takes place in the drawing in FIG

Essentially from left to right.

In a left-hand area in the drawing, a rotational speed 302 or the rotational speed signal 136 is fed to a block 304 as an input variable. The block 304 represents rotating masses of the internal combustion engine 100, which can influence a time course 403 (see FIG. 4) of the rotational speed 302. Two diagrams 306 and 308 show timings of the rotational speed 302 and of an output signal 310 of the block 304, as used by the control and / or

Control device 120 according to the method used or determined. The output signal 310 is fed to a subsequent block 312 as an input variable.

Block 312 forms a first derivative ("d / dt") of the output 310. An output 313 of block 312 is applied to a first input of an adder 314. The output signal 313 forms a first contribution to the torque 138, the first contribution characterizing mechanical effects on the cylinder 12 and the crankshaft 132.

In an upper part of FIG. 3 in the drawing, a pressure signal 316 characterizing the boost pressure P22 is supplied to a block 318 as an input variable. Block 318 includes a compression model of a respective cylinder 1 12 using a polytropic relationship to determine a "pumping pressure" (corresponding to a compression moment, M _K OMPRESSION, see below) due to thermodynamic effects upon compression and / or expansion of gas. A diagram 320 shows a time characteristic of an output signal 322 of the block 318. The output signal 322 forms a second contribution to the torque 138 and thus characterizes a

Gas compression as a result of a movement of a piston in the respective cylinder 1 12. The output signal 322 is a second (inverse) input of the adder

314 supplied. Thus, the adder 314 forms a difference of the first one and second article, see Equation (5) below. One

Output 326 - see graph 324 - of adder 314 is filtered in a following block 328. An output signal (not numbered) of block 328 is fed to a following block 330 as an input. At block 330, supplemental operations may be added as appropriate

Corrections are made.

Finally, at the output of the block 330, the torque 138 (M-COMBUSATION, internal torque) generated by the combustion of the fuel-air mixture of the internal combustion engine 100 is determined. In total, to the

Block diagram 300 of Figure 3, the following equation (5) are given:

(5) M COMBUSTION ⁼ ® * ^- "^ KOMPRESSION 'WObei drive torque generated by combustion in cylinder 1 12;

Moment of inertia of the rotating masses of

Internal combustion engine 100;

Angular velocity of the crankshaft 132; and

Compression torque, which is characterized by the movement of the piston in the cylinder 1 12.

FIG. 4 shows three diagrams 400, 402 and 404 with signals as a function of the angle of rotation 406 of the crankshaft 132, wherein the angle of rotation 406 is plotted on a respective abscissa. It is understood that the rotation angle 406 can optionally be converted to a time using the speed 302.

In the diagram 400 in the upper left area of the drawing of FIG. 4, a time profile 401 of the cylinder internal pressure 127 for a single cylinder 1 12 is plotted against the angle of rotation 406 of the crankshaft 132. Starting from a comparatively low value, the cylinder internal pressure 127 increases steeply and reaches the maximum value PZmax, which is specific for the respective cylinder 12. Thereafter, the in-cylinder pressure 127 falls steeply on a turn comparatively low value. The illustrated curve has a period of 720 ° of the rotation angle 406.

In the diagram 402 in the upper right area of the drawing of FIG. 4, a time profile 403 of the rotational speed signal 136 is above the rotational angle 406

applied. The time course 403 of the speed signal 136 corresponds to

Substantially a sinusoid, wherein constantly "irregularities" are superimposed with a comparatively small amplitude. The illustrated curve has a period of 180 ° of the rotation angle 406.

In the diagram 404 in the lower part of the drawing of FIG. 4, time profiles 401 for a respective cylinder internal pressure 127 are shown above FIG

Rotation angle 406 applied to all four cylinders 1 12a to 1 12d superimposed in succession. In the present case, the respective maximum values PZmax1, PZmax2, PZmax3 and PZmax4 have mutually different values. An arrow 408 symbolizes the determination of the cylinder internal pressure 127 for the remaining cylinders 1 12b to 1 12d, which are not carried out with the cylinder pressure sensor 128.

This determination preferably takes place in such a way that, in a first step, for the guide cylinder 1 12a, a relationship between the time profile 401 of FIG

Cylinder internal pressure 127 and the time course 403 of the speed signal 136 is determined in the associated period. In a second step, the determined relationship is then used to determine from a respective time segment of the rotational speed signal 136 for each of the remaining cylinders 1 12b to 12d the associated time profile 401 of the in-cylinder pressure 127. In particular, the abovementioned "irregularities" of the

Speed signal 136 with a. From this, using the rotation angle 406, an indicated mean pressure 602 (see FIG. 6) and a fraction 502 of the burned fuel quantity (see FIG. 5) can be determined.

FIG. 5 shows a diagram 500 with the fraction 502 of the burned

Fuel quantity (ordinate) over the rotation angle 406 (abscissa) of the crankshaft 132. Three horizontal dashed lines correspond to proportions 502 of the burned fuel quantity of 20%, 50% and 100%. The proportion 502 of the amount of fuel burned can, for example, using a integral heat release or an integral energy release of the running in the cylinder 1 12 combustion process can be determined.

In a vicinity of a top dead center of the piston, corresponding to a value of 0 ° of the rotation angle 406, combustion of the fuel in the respective cylinder 1 starts. The share 502 of the burned takes

Amount of fuel above the rotation angle 406 monotonously until it reaches a value of about 100%, that is, the fuel injected into the cylinder 1 12 is substantially burned.

In the present case, the amount 502 of the amount of fuel burnt in the present case is 20% at a rotation angle 406a and in the present case 50% at a rotation angle 406b. It can be seen that there is a reversibly unambiguous relationship between the fraction 502 of the quantity of fuel burnt and the angle of rotation 406 of the crankshaft 132. However, this relationship is dependent on the respective course of the combustion in the cylinder 1 12. Differently proceeding burns thus give each a different (numerical) relationship between the proportion 502 of the burned fuel quantity and the rotation angle 406th

FIG. 6 shows a three-dimensional diagram 600 of the maximum value PZmax of the cylinder internal pressure 127 as a function of the indicated mean pressure 602 in the cylinder 1 12 (the axis runs obliquely left-behind in the drawing) and in dependence on the angle of rotation 406 of the crankshaft 132 (FIG Axis runs obliquely in the drawing to the right-rear). The front lower corner of the diagram 600 in the drawing begins in each case with a finite value of the indicated mean pressure 602 and the angle of rotation 406. A respective zero point is therefore not visible in FIG. A partially slightly curved surface shown in the diagram 600 shows a dependency 604 of the maximum value PZmax of the cylinder internal pressure 127 from the indicated mean pressure 602 and the rotation angle 406. In this case, the dependency 604 is one for FIGS. 6, 7, 8, 9 and 10 each

specific value of speed 133 parameterized. In FIG. 6, the rotational speed 133 exemplarily has a value of 1200 rpm (revolutions per minute). Another parameter of the graph 600 is the amount 502 of the burned fuel quantity. In the figure 6 and in the following figures 7, 8, 9 and 10, the proportion 502 constant example, a value of 50%. This value thus likewise characterizes the respective dependency 604. For differently selected values of the fraction 502 of the quantity of fuel burned, correspondingly different dependencies 604 of the

Maximum value PZmax of the cylinder internal pressure 127 with respect to the other variables or parameters characterizing the diagram 600 result. However, the method of determining the maximum value PZmax of the in-cylinder pressure 127 also works with values deviating from 50% for the fraction 502 of the burned fuel amount in a comparable manner.

The dependency 604 can be generally represented by a following equation (1):

(1) PzMaxpZyl] = f (N, PMIpZyl], MFBxy% [iZyl], CA), where

PzMax = maximum value PZmax of the in-cylinder pressure 127;

f (...) = function;

N = rotational speed 133 of the internal combustion engine 100 in rpm (revolutions per minute);

PMI = indexed mean pressure 602 (unit: bar);

MFBxy = share 502 (percentage) of the burned fuel quantity;

[iZyl] = index for the respective cylinder 1 12; and

CA = angle of rotation 406 of the crankshaft 132.

As an alternative to the parameterization by means of discrete values for the rotational speed 133, the dependency 604 shown in FIG. 6 can be corrected by means of a function dependent on the rotational speed 133. However, this is not shown in FIG.

In the present case, the dependency 604 is stored in the data memory 124 by means of a (multi-dimensional) map. Alternatively or additionally, the dependency 604 is stored by means of one or more tables or is generated at least partially by means of one or more polynomial functions. Furthermore, it is possible to determine the dependency 604 using a neural network. A neural network can relatively easily determine and / or calculate and / or exchange and / or process and / or correlate a comparatively large number of variables.

The dependence 604 is determined for a respective type of internal combustion engine 100 or for a respective type of cylinder 1 12 in a preliminary test, for example on a so-called "test bench" at a manufacturer of the

Motor vehicle. In the present case, the dependency 604 is determined by means of a

data-based modeling using an ASCMO model. The term "ASCMO" includes generation of a global model that includes a variety of variables and / or quantities and their respective relationships or correlations to operate the engine 100 in a variety of operating conditions.

FIGS. 7, 8, 9 and 10, similarly to FIG. 6, show the dependency 604 of the in-cylinder pressure 127 on the rotational speed 133, the indicated mean pressure 602, the amount of burnt fuel 502 and the rotational angle 406 of the crankshaft 132 , 8, 9 and 10 respective value of the rotational speed 133 in the order given is exemplified 1600 rpm, 2000 rpm, 2400 rpm and 2800 rpm. Figure 1 1 shows a first flowchart for carrying out the method for

Operating the internal combustion engine 100, which in particular in a

Application phase ("preliminary test") for the internal combustion engine 100 can be performed. In a start block 700, the procedure shown in FIG. 11 begins. In a following block 702, the dependency 604 between the maximum value PZmax, the rotational speed signal 136 or the rotational speed 133, the indicated mean pressure 602, the fraction 502 of the burned fuel quantity and the rotational angle 406 of the crankshaft 132 is determined. This is done, for example, using the block diagram 300 of FIG. 3 or the diagrams 400, 402 and 404 of FIG. 4. The determined dependency 604 is stored in the data memory 124 in a following block 704 and is thus ready for a "normal" operation of the internal combustion engine 100. In an end block 706, the procedure illustrated in FIG. 11 ends.

FIG. 12 shows a second flow chart for carrying out the method for operating the internal combustion engine 100, which is particularly in one

Normal operation of the internal combustion engine 100 can be performed. In a start block 708, the procedure illustrated in FIG. 12 begins.

In a following block 710, using the stored dependency 604, the current (operating point-dependent) maximum values PZmax for the cylinders 1 12a to 12d are determined. In a following block 712, the operation of the internal combustion engine 100 is controlled or regulated using the current maximum values PZmax determined in this way. This takes place, for example, according to the flowchart shown in FIG. In an end block 714, the procedure shown in FIG. 12 ends, which can be carried out as often as desired and for any desired cylinder 12.

Claims

claims

1 . Method for operating an internal combustion engine (100), wherein a

Cylinder internal pressure (127) in at least one cylinder (1 12) of

Internal combustion engine (100) is determined, characterized in that a maximum value (PZmax) for the cylinder internal pressure (127) in dependence (604) of a rotational speed (133) and / or a rotational speed signal (136) of the internal combustion engine (100), an indicated mean pressure (602), a fraction (502) of a burned amount of fuel and a rotation angle (406) of a crankshaft (132) is determined.

2. The method according to claim 1, characterized in that the dependency (604) for a respective type of internal combustion engine (100) or for a respective type of cylinder (1 12) is determined in a preliminary experiment.

3. The method according to claim 1 or 2, characterized in that the

Dependence (604) is determined by means of a data-based modeling, in particular using an ASCMO model.

4. The method according to claim 1, characterized in that the indicated mean pressure (602) and / or the fraction (502) of the burned fuel quantity are individually for each cylinder by means of a polytropic relationship depending on a boost pressure (P22) and dependent on a time course (403 ) of the speed signal of (136)

Internal combustion engine (100) is determined.

5. The method according to at least one of claims 1 to 3, characterized

in that the indicated mean pressure (602) and / or the fraction (502) of the burned fuel quantity depend on a time characteristic (401) of the cylinder internal pressure (127) in a guide cylinder (12a) of the cylinder

Internal combustion engine (100) and dependent on a time course (403) of the rotational speed signal (136) of the internal combustion engine (100) is determined, and that the thus determined indicated mean pressure (602) and / or the determined portion (502) of the burned fuel quantity is used to the indicated average pressure (602) and / or the proportion (502) of the burned fuel quantity in the other cylinders (1 12b, 1 12c, 1 12d) of the

Close internal combustion engine (100).

Method according to at least one of the preceding claims, characterized in that the dependency (604) between the maximum value (PZmax) for the in-cylinder pressure (127), the indicated mean pressure (602), the fraction (502) of the burned fuel quantity and the rotation angle (406 ) of the crankshaft (132), wherein the dependence (604) is corrected by means of a function dependent on the rotational speed (133) of the crankshaft (132).

Method according to at least one of the preceding claims, characterized in that the dependency (604) between the maximum value (PZmax) for the in-cylinder pressure (127), the indicated mean pressure (602), the fraction (502) of the burned fuel quantity and the angle of rotation ( 406) of the crankshaft (132) is determined, wherein the dependence (604) by means of the rotational speed (133) of the crankshaft (132) is parameterized.

Method according to at least one of the preceding claims, characterized in that the maximum value (PZmax) for the in-cylinder pressure (127) using at least one polynomial function and / or at least one characteristic field as a function of (604) from the rotational speed (133) and / or the Speed signal (136), the indicated mean pressure (602), the fraction (502) of the burned fuel amount and the rotation angle (406) of the crankshaft (132) is determined. 9. The method according to at least one of the preceding claims, characterized in that in a first step by means of a neural network, the dependence (604) between the maximum value (PZmax) for the in-cylinder pressure (127), the rotational speed (133) and / or

Speed signal (136), the indicated mean pressure (602), the fraction (502) of the burned fuel quantity and the rotation angle (406) of the crankshaft

(132) is determined, and that in a second step by means of the neural Network of the maximum value (PZmax) for the in-cylinder pressure (127) using the determined dependence (604) is determined.

10. control and / or regulating device (120) for an internal combustion engine (100), characterized in that it is adapted to carry out the method according to one of claims 1 to 9.

1 1. Computer program (122), characterized in that it

is programmed to carry out the method according to one of claims 1 to 9.

12. Storage medium, characterized in that it comprises a computer program (122) according to claim 1 1.