DE102008001784B4 - Control device, method, computer program and computer program product for operating an internal combustion engine - Google Patents

Abstract

Method for controlling an internal combustion engine (1000), in which fuel is injected into a combustion chamber (1075) for combustion by means of a first injection valve (1040) and by means of a second injection valve (1045), characterized in that it comprises the following steps: a) specification a first amount of fuel to be injected, b) actuating the first injection valve (1040) to inject the first amount of fuel to be injected in accordance with a first assignment rule (Z1), the first amount of fuel to be injected has a first setpoint value (S1) of a first control signal (205), in particular by means of interpolation, assigns, c) determining a first actual value (I1) of an operating characteristic of the internal combustion engine (1000) resulting from the combustion of a first actual fuel quantity (q) injected by the activation of the first injection valve (1040) in step b), d) specifying a second fuel quantity to be injected, e) triggering the e rsten injector (1040) for injecting the first quantity of fuel to be injected and additionally actuating the second injector (1045) for injecting the second quantity of fuel to be injected in accordance with a second assignment rule (Z2), the second quantity of fuel to be injected has a second setpoint value (S2) of a second control signal (225 ), in particular by means of interpolation, f) determining a second actual value (12) of the first actual fuel quantity (q) injected by the combustion of the control of the first injection valve (1040) in step e) and one of the control of the second injection valve (1045) injected in step e) second actual fuel quantity (q2) resulting operating parameter of the internal combustion engine (1000), g) determining a deviation (A) between the first actual value (I1) and the second actual value (12) , in particular an excess fuel quantity, h) determination of a correct ized second assignment rule (Z2corr) of the second injection valve (1045), by means of which the second setpoint (S2) of the second control signal (225) is assigned to the deviation (A).

Description

State of the art

The invention is based on a method, a control device, a computer program and a computer program product for operating an internal combustion engine according to the type of the independent claims.

Methods and devices for operating an internal combustion engine are known from the prior art, in which fuel is injected with a first injection valve into an intake manifold and with a second injection valve directly into a combustion chamber of the internal combustion engine, valve characteristics being used, one for the respective valve Describe the characteristic assignment of a predetermined fuel quantity to a target value for a control signal. However, these valve characteristics do not take into account, for example, valve-specific deviations of a fuel quantity actually injected with the valve from a predetermined fuel quantity to be injected, which are caused by manufacturing tolerances.

From the published application US 2005/0 235 960 A1 an electronic control unit is known which determines a correction value and a second correction value. The first correction value serves to compensate for a deviation of an actual air-fuel ratio with respect to a target air-fuel ratio if fuel is fed into each combustion chamber. The supply takes place via an intake pipe and a direct injection. The second correction value serves to compensate for a further deviation of an actual air-fuel ratio with respect to a target air-fuel ratio if fuel is fed into each combustion chamber. A ratio of the injection quantity into the intake pipe quantity to the total injection quantity plays a role here.

From the published application EP 1 930 577 A1 is known to make multiple injections for a combustion process in a combustion chamber. A controller is provided that corrects an injection quantity. Pre-injections and post-injections are provided, among other things. Ratios of requested fuel injections and corresponding injection commands are stored. Furthermore, there is a switch between different modes. One mode provides post-injection that follows a main injection. Another mode only provides one main injection.

Disclosure of the invention

Advantages of the invention

1. a) eine erste einzuspritzende Kraftstoffmenge vorgegeben wird,
2. b) ein erstes Einspritzventil zum Einspritzen der ersten einzuspritzenden Kraftstoffmenge gemäß einer ersten Zuordnungsvorschrift angesteuert wird, die der ersten einzuspritzenden Kraftstoffmenge einen ersten Sollwert eines ersten Ansteuersignals, insbesondere mittels Interpolation, zuordnet,
3. c) ein erster Ist-Wert einer aus der Verbrennung einer durch die Ansteuerung des ersten Einspritzventils eingespritzten ersten tatsächlichen Kraftstoffmenge resultierenden Betriebskenngröße der Brennkraftmaschine ermittelt wird,
4. d) eine zweite einzuspritzende Kraftstoffmenge vorgegeben wird,
5. e) das erste Einspritzventil zum Einspritzen der ersten einzuspritzenden Kraftstoffmenge angesteuert wird, und zusätzlich ein zweites Einspritzventil zum Einspritzen der zweiten einzuspritzenden Kraftstoffmenge gemäß einer zweiten Zuordnungsvorschrift angesteuert wird, die der zweiten einzuspritzenden Kraftstoffmenge einen zweiten Sollwert eines zweiten Ansteuersignals, insbesondere mittels Interpolation, zuordnet,
6. f) ein zweiter Ist-Wert der aus der Verbrennung der durch die Ansteuerung des ersten Einspritzventils eingespritzten ersten tatsächlichen Kraftstoffmenge und einer durch die Ansteuerung des zweiten Einspritzventils eingespritzten zweiten tatsächlichen Kraftstoffmenge resultierenden Betriebskenngröße der Brennkraftmaschine ermittelt wird,
7. g) eine Abweichung zwischen dem ersten Ist-Wert und dem zweiten Ist-Wert, insbesondere ein Kraftstoffmengenüberschuss, ermittelt wird,
8. h) eine korrigierte zweite Zuordnungsvorschrift des zweiten Einspritzventils ermittelt wird, durch die der zweite Sollwert des zweiten Ansteuersignals der Abweichung zugeordnet wird.

In contrast, the method according to the invention, the control device according to the invention, the computer program according to the invention and the computer program product according to the invention with the features of the independent claims have the advantage that

1. a) a first fuel quantity to be injected is specified,
2. b) a first injection valve for injecting the first quantity of fuel to be injected is controlled according to a first assignment rule, which assigns a first setpoint of a first activation signal, in particular by means of interpolation, to the first quantity of fuel to be injected,
3. c) a first actual value of an operating parameter of the internal combustion engine resulting from the combustion of a first actual fuel quantity injected by the control of the first injection valve is determined,
4. d) a second quantity of fuel to be injected is specified,
5. e) the first injection valve is controlled for injecting the first quantity of fuel to be injected, and in addition a second injection valve for injecting the second quantity of fuel to be injected is activated in accordance with a second assignment rule which assigns the second quantity of fuel to be injected a second setpoint value of a second activation signal, in particular by means of interpolation,
6. f) a second actual value of the operating parameter of the internal combustion engine resulting from the combustion of the first actual fuel quantity injected by the activation of the first injection valve and a second actual fuel quantity injected by the activation of the second injection valve is determined,
7. g) a deviation between the first actual value and the second actual value, in particular an excess fuel quantity, is determined,
8. h) a corrected second assignment rule of the second injection valve is determined, by means of which the second setpoint value of the second control signal is assigned to the deviation.

In this way, valve-specific deviations of the injected second actual fuel quantity from the second injected Corrected fuel quantity of the second injector. The correction of the deviations of the second injection valve is made possible by the additional injection by means of the first injection valve also in a range of the second fuel quantity to be injected which is so small that the second actual fuel quantity is not sufficient to supply the internal combustion engine with only the second actual fuel quantity operate.

The measures listed in the dependent claims allow advantageous developments and improvements of the method specified in the main claim.

It is particularly advantageous if at least one of steps d) to h) is repeated at least once. As a result, more than one pair of values of the corrected second assignment rule is determined and displayed, for example, as a characteristic curve. This improves the accuracy of the method according to the invention.

It is particularly advantageous if steps d) to h) are repeated, and when steps d) to h) are run through for the first time, a first value is selected for the second quantity of fuel to be injected, and the second quantity of fuel to be injected is repeated for at least one repetition of the steps d) to h) in step d) is changed by a predetermined amount. By repeating steps d) to h), the corrected second assignment rule is determined systematically. This simplifies the application of the method according to the invention.

It is particularly advantageous if value pairs of the corrected second assignment rule are determined in step h), and steps d) to h) are repeated until the number of value pairs of the corrected second assignment rule determined in step h) exceeds a first predetermined number . As a result, the method according to the invention can be ended in a simple manner if a sufficient number of value pairs of the corrected second assignment rule have been determined.

It is particularly advantageous if the first predetermined number depends on the largest second quantity of fuel to be injected, which is to be implemented in the internal combustion engine by means of the second injection valve, the desired resolution of the corrected second allocation rule and / or the measurement accuracy of one used to record the operating parameter of the internal combustion engine Measuring device is determined. This makes it particularly easy to determine the number of repetitions required.

It is particularly advantageous if the predetermined amount is changed by the second fuel quantity to be injected in at least one repetition, depending on the target resolution of the corrected second assignment rule and / or the measurement accuracy of a measuring device used to record the operating parameter of the internal combustion engine. As a result, the resolution of the corrected second assignment rule is determined in a particularly simple manner.

It is particularly advantageous if the second assignment rule, in particular as a valve characteristic, is stored in a third memory unit in the control unit. As a result, the method according to the invention is carried out in a particularly simple manner.

It is particularly advantageous if the corrected second assignment rule, in particular as a characteristic curve, is stored in the third memory unit in the control unit. As a result, the method according to the invention is carried out in a particularly simple manner.

It is particularly advantageous if the corrected second assignment rule replaces the second assignment rule. As a result, the method according to the invention is carried out in a particularly simple manner.

1. i) das zweite Einspritzventil der Brennkraftmaschine gemäß dem zweiten Sollwert abhängig von der korrigierten zweiten Zuordnungsvorschrift aus Schritt h), insbesondere durch Interpolation, angesteuert wird. Dadurch wird die zweite einzuspritzende Kraftstoffmenge mittels des zweiten Einspritzventils viel genauer umgesetzt.

It is particularly advantageous if in an additional step

1. i) the second injection valve of the internal combustion engine is controlled in accordance with the second setpoint depending on the corrected second assignment rule from step h), in particular by interpolation. As a result, the second quantity of fuel to be injected is implemented much more precisely by means of the second injection valve.

It is particularly advantageous if, when steps d) to h) are run through for the first time, the first value for the second quantity of fuel to be injected does not exceed the predetermined first threshold value. As a result, the corrected second assignment rule is systematically determined in a particularly simple manner from small values for the second fuel quantity to be injected to large values for the second fuel quantity to be injected.

It is particularly advantageous if, during the first passage through steps d) to h), the first value for the second quantity of fuel to be injected does not exceed the predetermined first threshold value, and steps d) to h) are repeated until the deviation a predetermined second Threshold value exceeds, the second fuel quantity to be injected in at least one Repetition of step d) is increased by the predetermined amount. As a result, the lowest point of a characteristic curve, which represents the corrected second assignment rule, is determined particularly easily.

It is particularly advantageous if, when steps d) to h) are run through for the first time, the first value for the second quantity of fuel to be injected exceeds the predetermined first threshold value. As a result, the corrected second assignment rule is systematically determined in a particularly simple manner from large values for the second fuel quantity to be injected to small values for the second fuel quantity to be injected.

It is particularly advantageous if, during the first passage through steps d) to h), the first value for the second quantity of fuel to be injected exceeds the predetermined first threshold value, and steps d) to h) are repeated until the deviation (A) falls below the predetermined second threshold value, the second fuel quantity to be injected being reduced by the predetermined amount in at least one repetition of step d). As a result, the lowest point of a characteristic curve, which represents the corrected second assignment rule, is determined particularly easily.

It is particularly advantageous if the resulting operating parameter of the internal combustion engine is the oxygen concentration of the exhaust gas of the internal combustion engine. As a result, the resulting operating parameter is determined in a particularly simple manner using already existing sensors.

It is particularly advantageous if there is a switchover between the determination of the first actual value of the resulting operating parameter of the internal combustion engine and the determination of the second actual value of the resulting operating parameter of the internal combustion engine as a function of a variable characterizing a combustion cycle of the internal combustion engine, with one combustion cycle at least one Combustion includes. The assignment of the first actual value to the first actual fuel quantity and the second actual value to the first actual fuel quantity and to the second actual fuel quantity takes place particularly reliably.

It is particularly advantageous if the first actual value of the resulting operating parameter of the internal combustion engine and the second actual value of the resulting operating parameter of the internal combustion engine are recorded between a first point in time and a second point in time during the combustion cycle of the internal combustion engine, the first point in time and the second point in time Point in time can be determined depending on the variable characterizing the combustion cycle of the internal combustion engine. As a result, the first actual value and the second actual value are determined particularly reliably.

It is particularly advantageous if the first and the second point in time are determined in such a way that the exhaust gas from the internal combustion engine arrives from the combustion chamber after combustion between the first point in time and the second point in time at a measuring device arranged in the internal combustion engine for recording the operating parameter of the internal combustion engine. As a result, the first actual value and the second actual value are determined particularly precisely.

It when the variable characterizing the combustion cycle of the internal combustion engine is a crankshaft angle and / or a rotational speed of the internal combustion engine is particularly advantageous. This makes it particularly easy to determine the first point in time and the second point in time.

It when the first control signal of the first injection valve is a first electrical control duration and the second control signal of the second injection valve is its second electrical control duration is particularly advantageous. As a result, the first injection valve and the second injection valve are activated in a particularly simple manner.

Figure list

• 1 eine schematische Darstellung einer Brennkraftmaschine,
• 2 ein Diagramm für die Ansteuersignale der Einspritzventile,
• 3 ein Diagramm der Einspritzmenge in Abhängigkeit von der elektrischen Ansteuerdauer.
• 4 ein Ablaufdiagramm des erfindungsgemäßen Verfahrens.

Embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it:

• 1 1 shows a schematic illustration of an internal combustion engine,
• 2nd a diagram for the control signals of the injection valves,
• 3rd a diagram of the injection quantity as a function of the electrical activation period.
• 4th a flowchart of the method according to the invention.

Description of the embodiments

In 1 an internal combustion engine, for example, a gasoline or diesel engine is shown and with 1000 designated. The internal combustion engine 1000 can have one or more combustion chambers 1075 feature, of which for the sake of clarity 1 only one is shown. The internal combustion engine also includes an intake manifold 1050 that has an inlet valve 1055 with the combustion chamber 1075 connected is. Via the suction pipe 1050 becomes the combustion chamber 1075 Fresh air and one through a first injector 1040 one in the intake manifold 1050 first actual fuel quantity q1 injected. A second actual amount of fuel q2 is through a second injector 1045 directly into the combustion chamber 1075 injected. In the case of an Otto engine is in the combustion chamber 1075 a spark plug 1085 provided by the resulting fuel-air mixture in the combustion chamber 1075 is ignited in a manner known to those skilled in the art. An exhaust gas resulting from the combustion is discharged through an exhaust valve 1060 into an exhaust pipe 1065 diverted. An oxygen concentration of the exhaust gas from a lambda sensor is used as an operating parameter of the internal combustion engine resulting from the combustion of the injected first and the injected second fuel quantity 1070 the one in the exhaust pipe 1065 is arranged, determined.

The internal combustion engine 1000 also includes one in the intake manifold 1050 arranged in 1 Throttle valve, not shown, for controlling the amount of fresh air that the combustion chamber 1075 is fed. The control of the ignition, the intake and exhaust valves and the throttle valve is in 1 not shown and takes place in a manner known to the person skilled in the art, for example in order to implement a predetermined driver request.

The internal combustion engine further comprises a control device 1005.

In the control unit 1005 is a first default unit 1010 arranged that a first control unit 1011 specifies a first quantity of fuel to be injected. The first control unit 1011 determines a first control signal 205 according to a first assignment rule Z1. The first assignment rule Z1 assigns a first setpoint S1 of the first control signal to each first fuel quantity to be injected 205 to. The first fuel injector 1040 is from the first control unit 1011 according to the first control signal 205 controlled. The first assignment rule Z1 is, for example, a linear or non-linear valve characteristic curve, which is provided by the manufacturer of the first injection valve 1040 is made available. Alternatively, the first assignment rule Z1 is determined, for example, in a test bench or by mathematical modeling in a manner known to the person skilled in the art.

A time course of the first control signal 205 to control the first injection valve 1040 is in 2nd shown as an example. The first fuel injector 1040 is accordingly on a falling edge of the first control signal 205 opened and with a rising edge of the first control signal 205 closed. The distance between the falling and rising edge represents a first electrical activation period t1 of the first injector 1040 The first electrical activation period t1 is from the first control unit 1011 from the first fuel quantity to be injected in accordance with the first assignment rule Z1 certainly. The first assignment rule Z1 then establishes a first relationship between the first fuel quantity to be injected and the first electrical activation period t1 represents.

The control unit also includes 1005 a second default unit 1015 that a second control unit 1016 specifies a second fuel quantity to be injected. The second control unit 1016 determines a second control signal 225 according to a second assignment rule Z2 . The second assignment rule Z2 is in a third storage unit 1013 stored and assigns a second setpoint to every second fuel quantity to be injected S2 of the second control signal 225 to. The second injector 1045 is from the second control unit 1016 according to the second control signal 225 controlled. The second assignment rule Z2 is, for example, a linear or non-linear valve characteristic curve that is provided by the manufacturer of the second injection valve 1045 is made available. Alternatively, the second assignment rule Z2 determined, for example, in a test bench or by mathematical modeling in a manner known to the person skilled in the art.

The time course of the second control signal 225 is in 2nd shown as an example. Here, a falling edge means opening the second injector 1045 and a rising edge closing the second injector 1045 . The distance between the falling and rising edge represents a second electrical activation period t2 of the second injector 1045 The second electrical control period t2 is from the second control unit 1016 from the second quantity of fuel to be injected in accordance with the second assignment rule Z2 certainly. The second assignment rule Z2 then establishes a second relationship between the second fuel quantity to be injected and the second electrical actuation duration t2 represents.

2nd also shows that the second electrical drive duration t2 of the second injector 1045 from the second control unit 1015 is specified so that the second electrical control period t2 each time the second injection valve is activated 1045 is greater than the second electrical activation period t2 with the previous control of the injection valve 1045 . As in 2nd are shown, the opening times of the first injection valve characterized by the falling flanks 1040 and the second injector 1045 chosen so that the second injector 1045 is opened while the first injector 1040 is open. The method according to the invention is not based on this arrangement of the opening time and the increase in the second electrical actuation durations t2 at each repetition is limited, but can also be tw for other selection of the opening times and second electrical activation durations, for example reduction or random selection of the second electrical activation durations t2 be applied accordingly.

In the control unit 1005 is also a first investigation unit 1020 arranged, the oxygen concentration of the exhaust gas from the lambda sensor 1070 is transmitted. In addition, a crankshaft angle of one in the internal combustion engine 1000 arranged crankshaft angle sensor 1080 to the investigative unit 1020 transmitted.

The first investigative unit 1020 receives the from the lambda sensor 1070 transmitted signals and stores them in a manner known to those skilled in the art, for example in an in 1 volatile memory, not shown. The first investigative unit 1020 determines the first actual value I1 and a second actual value I2 of the oxygen concentration of the exhaust gas of the internal combustion engine 1000 . The first actual value I1 or the second actual value I2 is calculated between a first point in time and a second point in time. The first point in time is after the end of a combustion cycle. The second point in time is after the first point in time. The combustion cycle consists of the cycles of suction, compression, expansion, and pushing out. The first time and the second time is determined so that the exhaust gas of the internal combustion engine 1000 from the combustion chamber 1075 after the combustion between the first point in time and the second point in time on the lambda sensor 1070 flows past. The first point in time and the second point in time are determined in a manner known to the person skilled in the art, for example by mathematical modeling or on a test bench.

The first investigative unit 1020 switches between the calculation of the first actual value I1 and the calculation of the second actual value I2, for example depending on the crankshaft angle. The crankshaft angle can also be determined, for example, in a manner known to those skilled in the art as a function of the speed of the internal combustion engine. The switchover between the calculation of the first actual value I1 and the second actual value I2 takes place after completion of one or more combustion cycles. For example, the first actual value I1 is determined only once for a combustion cycle and then switched over. The second actual value I2 is then determined for the next combustion cycle. The crankshaft angle assigned to the end of the cycle of pushing out marks the end of the combustion cycle. The determination of the time for the switchover by means of the crankshaft angle is given here as an example. In the same way, the time for switching can also be determined from other operating parameters of the internal combustion engine, for example the speed of the internal combustion engine.

Next is in the control unit 1005 a first storage unit 1025 arranged to which the first actual value I1 from the determination unit 1020 is transmitted. The transmission takes place as soon as the first actual value I1 from the determination unit 1020 was determined.

Next is in the control unit 1005 a second storage unit 1022 arranged to which the second actual value I2 from the determining unit 1020 is transmitted. The transmission takes place as soon as the second actual value I2 from the determination unit 1020 was determined.

The comparison unit 1030 compares the first actual value I1 from the first storage unit 1025 with the second actual value I2 from the second storage unit 1022 and determines a deviation A of the oxygen concentration of the exhaust gas by subtracting the two values: $$\text{A}=\text{I.}1-\text{I.}\mathrm{2nd}$$

The deviation A is from the comparison unit 1030 to a third investigation unit 1035 to hand over. The third investigation unit 1035 determines a corrected second assignment rule Z2Korr of the second injection valve 1045 and transmits this to the third storage unit 1013 . The corrected second assignment rule Z2Korr is stored there. The corrected second assignment rule Z2Korr is compared with in 4th shown flow chart of the inventive method determined.

The method according to the invention starts as soon as the internal combustion engine 1000 and the control unit 1005 be put into operation. In a manner known to those skilled in the art, this is done, for example, in a motor vehicle by switching on the ignition.

After starting the program, the step 400 it is checked whether the corrected second assignment rule Z2Korr should be determined. If this is the case, it becomes a step 405 branches. Otherwise it becomes a step 440 branches. The corrected second assignment rule Z2Korr should be determined, for example, until the number of determined pairs of values of the corrected second assignment rule Z2Korr exceeds a first predetermined number.

The determination of the corrected second assignment rule Z2Korr is also intended, for example, after a certain number of operating hours the internal combustion engine 1000 respectively. This causes drift effects or wear and tear of the second injector 1045 considered.

The number of engine operating hours 1000 According to which the corrected second assignment rule Z2 Korr is to take place, for example in the case of a motor vehicle, this results from the service interval of the internal combustion engine 1000 . The determination and evaluation of the number of operating hours of the internal combustion engine 1000 takes place in a manner known to the person skilled in the art.

At step 405 is from the first investigative unit 1020 checked whether the first actual value I1 should be determined. If so, it becomes a step 412 branches if no to step 410 . The switchover between the calculation of the first actual value I1 and the second actual value I2 takes place after completion of one or more combustion cycles. For example, the first actual value I1 is determined only once for a combustion cycle and then switched over.

At step 412 is from the first default unit 1010 predefines the first fuel quantity to be injected and, for example, in a volatile memory of the control unit 1005 saved for later use. The size of the first quantity of fuel to be injected varies depending on the design of the internal combustion engine 1000 and, for example, in the case of an Otto engine in a motor vehicle, depending on the driver's request 5 to 25th mg per combustion cycle.

At step 413 on step 412 follows from the first control unit 1013 the first setpoint S1 for the first control signal 205 out 2nd determined, for example, by interpolation from the first assignment rule Z1 and the first injection valve 1040 with the first electrical activation period t1 controlled according to the first setpoint S1.

At step 414 on step 413 follows, is from the first determining unit 1020 the first actual value I1 of the oxygen concentration of the exhaust gas is determined and in the first storage unit 1025 saved. The method according to the invention is then carried out with step 420 continued. The first actual fuel quantity q1 typically deviates from the first fuel quantity to be injected, since during the injection through the first injection valve 1040 for example, due to manufacturing tolerances, the first quantity of fuel to be injected cannot be realized exactly. Because in the crotch 412 only the first injector 1040 from the first default unit 1010 the first fuel quantity to be injected has been specified, the first actual value I1 of the oxygen concentration of the exhaust gas can then be clearly assigned to the first actual fuel quantity q1 if the oxygen concentration of the exhaust gas is determined between the first point in time and the second point in time during which the exhaust gas of the internal combustion engine 1000 from the combustion chamber 1075 after combustion on the lambda sensor 1070 flows past.

At step 410 it is checked whether the step 415 has already been run through for the first time. If yes, the step becomes 411 if no, branches to the step 415 . For this purpose, a counter, for example in a computer program for implementing the method according to the invention, uses a variable tD, which is initialized with zero when the program is started. The variable tD then has the first run of the step 410 the value tD = 0.

At step 415 is from the first default unit 1010 the same first fuel quantity to be injected as specified in step 412 . For this purpose, the first quantity of fuel to be injected is obtained, for example, from the volatile memory of the control unit 1005 read. In addition, the second default unit 1015 predefines the second fuel quantity to be injected and for later use, for example in the volatile memory of the Control unit 1005 saved. For the second quantity of fuel to be injected, a first value is selected which does not exceed a predetermined first threshold value. The predetermined first threshold value varies depending on the design of the internal combustion engine 1000 and is, for example, in an Otto engine in a motor vehicle 1 up to 25mg per combustion cycle. For example, the first threshold value is selected as 2 mg depending on the smallest second actual injection quantity that can be realized by the second injection valve. Alternatively, the threshold value can also be chosen to be zero. Then no knowledge of the smallest realizable second actual injection quantity is required. It is also possible to choose the first value so that it does not fall below the first threshold. Then the first threshold value is selected to be 23 mg, for example. Every time you go through the step 415 the counter, for example the variable tD, is changed to a non-zero value, for example increased by one. The method according to the invention is then carried out in one step 416 continued.

At step 411 is from the first default unit 1010 the same first fuel quantity to be injected as specified in step 412 . For this purpose, the first quantity of fuel to be injected is obtained, for example, from the volatile memory of the control unit 1005 read. In addition, the second default unit 1015 predefines the second fuel quantity to be injected and for later use, for example, in the volatile memory of the control unit 1005 saved. The first value from step becomes the second fuel quantity to be injected 415 changed by a predetermined amount. For this purpose, the second quantity of fuel to be injected is obtained, for example, from the volatile memory of the control unit 1005 read. For example, the second quantity of fuel to be injected is increased by the predetermined amount if the first value in the step 415 was chosen so that it does not exceed the first threshold value, for example 5 mg. This procedure makes it particularly easy to systematically move from small second fuel quantities to be injected to large second fuel quantities to be injected. Alternatively, it is also possible to reduce the second fuel quantity to be injected by the predetermined amount. This is particularly useful if the first value in the step 415 was chosen so that it does not fall below the first threshold value, for example 23 mg. In this case it is particularly easy to systematically switch from large second fuel quantities to be injected to small second fuel quantities to be injected. The method according to the invention is then carried out with the step 416 continued.

The default amount from step 411 determines a desired resolution of the corrected second assignment rule Z2Korr and is selected, for example, to 1 mg. The desired resolution is selected, for example, as a function of the measurement accuracy of one for recording the operating parameter of the internal combustion engine 1000 used measuring device, for example the lambda sensor 1070 . The smallest second actual fuel quantity selected by the first determination unit is selected as the desired resolution 1025 from that of the lambda sensor 1070 detected oxygen concentration of the exhaust gas can be determined. Alternatively or additionally, the resolution can be dependent on one for operating the internal combustion engine 1000 provided combustion processes can be determined in a manner known to those skilled in the art.

At step 416 , is from the first control unit 1013 the first setpoint S1 for the first control signal 205 out 2nd for example by interpolation from the first assignment rule Z1 determined and the first injector 1040 with the first electrical activation period t1 controlled according to the first setpoint S1. In addition, the second control unit 1016 the second setpoint S2 for the second control signal 225 out 2nd for example by interpolation from the second assignment rule Z2 determined and the second injector 1045 with the second electrical control period t2 controlled according to the second setpoint S2. As a result, the first actual fuel quantity q1 from the first injection valve 1040 and a second actual amount of fuel q2 from the second injector 1045 injected.

At step 417 on step 416 follows, is from the first determining unit 1020 the second actual value I2 determines the oxygen concentration of the exhaust gas and in the second storage unit 1022 saved. The method according to the invention is then carried out with step 420 continued. The first actual fuel quantity q1 typically deviates from the first fuel quantity to be injected, since during the injection through the first injection valve 1040 for example, due to manufacturing tolerances, the first quantity of fuel to be injected cannot be realized exactly. The second actual quantity of fuel q2 typically deviates from the second quantity of fuel to be injected, since during the injection by the second injection valve 1045 for example, due to manufacturing tolerances, the second quantity of fuel to be injected cannot be realized exactly. Because in the crotch 415 the first injector 1040 from the first default unit 1010 the first quantity of fuel to be injected was specified and the second injector 1045 from the second default unit 1015 the second quantity of fuel to be injected has been specified, the second actual value can be I2 then clearly assign the oxygen concentration of the exhaust gas to the first actual fuel quantity q1 and the second actual fuel quantity q2 if the oxygen concentration of the exhaust gas is determined between the first point in time and the second point in time during which the exhaust gas of the internal combustion engine 1000 from the combustion chamber 1075 after combustion on the lambda sensor 1070 flows past.

At step 420 becomes the first actual value I1 from the first storage unit 1025 and the second actual value I2 from the second storage unit 1022 to the comparison unit 1030 transmitted. The comparison unit 1030 determines the deviation A between the first actual value I1 and the second actual value I2. The deviation A characterizes an excess fuel quantity, which is fed to the combustion by injecting the second actual fuel quantity q2 in addition to injecting the first actual fuel quantity q1.

At step 430 on step 420 follows, the deviation A is sent to a second determination unit 1035 which transmits the corrected second assignment rule Z2Korr of the second injection valve 1045 determined depending on the deviation A. For this purpose, the second actual fuel quantity q2 is determined from the deviation A of the oxygen concentration of the exhaust gas in a manner known to the person skilled in the art. The corrected second assignment rule Z2Korr then describes a pair of values that a second actual fuel quantity q2 a second electrical control duration t2 of the second injector 1045 assigns. The pair of values of the assignment rule Z2Korr is stored in the third storage unit 1013 saved.

The system then jumps back to step 400.

This creates a program loop through which several value pairs of the corrected second assignment rule Z2Korr are determined; the value pairs of the corrected second assignment rule Z2Korr are, for example, as one in 3rd characteristic curve shown 305 used, which represents the relationship between the second electrical control variable and the second actual fuel quantity for each valve. On the x-axis one in 3rd The coordinate system shown is, for example, the second electrical activation period t2 plotted in [ms]. The second actual fuel quantity q2 in [mg] is plotted on the y-axis. Out 3rd An example of a solenoid valve shows that the characteristic 305 based on the origin for short electrical control periods t2 initially remains zero, then increases nonlinearly slowly then more sharply and then for longer electrical control times t2 approximates a linear course. The resolution of the x-axis on which the second electrical control period t2 is directly dependent on the second quantity of fuel to be injected and is therefore constant for a constant predetermined amount. In the characteristic 305 Here, for example, the value pairs of the second assignment rule Z2Korr are those of the second electrical activation period t2 the second actual fuel quantity q2 is shown with a cross x. In a manner known to those skilled in the art, values can be between two pairs of values of the characteristic 305 can be determined, for example, by interpolation. The characteristic 305 is used to determine the second setpoint S2 for the second electrical control signal 225 used according to the second amount of fuel to be injected. This is the second electrical control period t2 as the second setpoint S2, for example from the characteristic curve 305 determined.

The range of the second actual fuel quantity q2 and the second electrical activation period t2 the characteristic 305 covers varies depending on the design of the internal combustion engine 1000 and is, for example, in an Otto engine in a motor vehicle 2nd up to 23mg.

From the resolution of the characteristic 305 , for example with the predetermined amount 1 mg, the first predetermined number of value pairs is determined by the choice of the predetermined first threshold value, for example at 2 mg. With a range from 2mg to 23mg, the first predetermined number of repetitions is obtained 20th . The first predetermined number thus becomes dependent on the largest second quantity of fuel to be injected, which is in the internal combustion engine 1000 by means of the second injection valve 1045 should be realized and the desired resolution of the corrected second assignment rule Z2Korr and / or the measurement accuracy of a to record the operating parameter of the internal combustion engine ( 1000 ) used measuring device determined.

In the method according to the invention, the change in the second fuel quantity by the predetermined amount does not have to be carried out each time step c) is repeated, for example if an average value is to be formed from two or more deviations A before the corrected second assignment rule Z2 corr is determined. In addition, the predetermined amount does not have to be constant during the method according to the invention. For example, it can be adapted to the resolution of the characteristic 305 to be reduced in areas where the characteristic curve is approximately linear. Conversely, the resolution can be increased to cover areas that show non-linear behavior.

At step 440 it is checked whether the corrected second assignment rule Z2 Korr has already been determined. If so, it becomes a step 450 branches. Otherwise to one step 460 .

At step 450 becomes the second assignment rule Z2 in the third storage unit 1013 by the corrected second assignment rule Z2Korr from the storage unit 1013 replaced and the procedure with the step 460 continued.

At step 460 become the first fuel injector 1040 and / or the second injection valve 1045 Controlled in a manner known to those skilled in the art, for example in order to implement a driver's request in a motor vehicle.

The system then jumps back to step 400.

The method according to the invention is carried out during each of the steps 400 to 460 ended when the internal combustion engine 1000 and / or the control unit 1005 for example in a motor vehicle can be switched off by a driver of the motor vehicle. These conditions are monitored in a manner known to the person skilled in the art and is shown in 4th not shown.

In a modified embodiment, the first threshold is determined as a lower range limit by the steps 415 to 430 are repeated until the deviation A exceeds a predetermined second threshold value. The second threshold is based on the signal resolution of the lambda sensor 1070 , or is chosen to be zero in order to detect the smallest possible deviation A. The first threshold value corresponds to the second actual fuel quantity q2 at which the deviation A exceeds the second threshold value. The second threshold value is chosen to be 1 mg, for example.

Instead of the second electrical control period described in the exemplary embodiment t2 a different manipulated variable of the second injection valve, for example a current signal, can also be used to carry out the method according to the invention.

The method according to the invention is not limited to that by the first injection valve 1040 into the intake manifold 1050 and through the second injector 1045 is injected directly into the combustion chamber. The method according to the invention can then be used if at least two injection valves are provided. Also in a different arrangement, for example of the first injection valve 1040 for injection directly into the combustion chamber 1075 and the second injector 1045 the method is used analogously for injection into the intake manifold.

Claims (23)

Method for controlling an internal combustion engine (1000), in which fuel is injected into a combustion chamber (1075) by means of a first injection valve (1040) and by means of a second injection valve (1045), characterized in that it comprises the following steps: a) specification a first quantity of fuel to be injected, b) actuating the first injection valve (1040) to inject the first quantity of fuel to be injected in accordance with a first assignment rule (Z1), the first quantity of fuel to be injected has a first setpoint value (S1) of a first control signal (205), in particular by means of interpolation, assigns, c) determining a first actual value (I1) of an operating characteristic of the internal combustion engine (1000) resulting from the combustion of a first actual fuel quantity (q ₁ ) injected by the activation of the first injection valve (1040) in step b), d) specification a second fuel quantity to be injected, e) control of the first injector (1040) for injecting the first quantity of fuel to be injected and additionally actuating the second injector (1045) for injecting the second quantity of fuel to be injected in accordance with a second assignment rule (Z2), the second quantity of fuel to be injected has a second setpoint value (S2) of a second control signal (225), in particular by means of interpolation, f) determining a second actual value (12) of the first actual fuel quantity (q ₁ ) injected by the combustion of the first injection valve (1040) in step e) and one by the control of the second injection valve (1045) injected in step e) second actual fuel quantity (q2) resulting operating parameter of the internal combustion engine (1000), g) determining a deviation (A) between the first actual value (I1) and the second actual value (12), in particular an excess fuel quantity, h) investigation ng a corrected second assignment rule (Z2korr) of the second injection valve (1045), by means of which the second setpoint (S2) of the second control signal (225) is assigned to the deviation (A). Procedure according to Claim 1 , in which at least one of steps d) to h) is repeated at least once. Procedure according to Claim 1 or 2nd , in which steps d) to h) are repeated, and when the steps d) to h) are run through for the first time, a first value is selected for the second quantity of fuel to be injected, and the second quantity of fuel to be injected in at least one repetition of steps d) to h) in step d) is changed by a predetermined amount. Procedure according to Claim 3 , in which value pairs of the corrected second assignment rule (Z2korr) are determined in step h), and steps d) to h) are repeated until the number of value pairs of the corrected second assignment rule (Z2korr) determined in step h) is a first exceeds the specified number. Procedure according to Claim 4 , in which the first predetermined number depends on the largest second quantity of fuel to be injected, which is to be implemented in the internal combustion engine (1000) by means of the second injection valve (1045), the target resolution of the corrected second assignment rule (Z2corr) and / or the measurement accuracy of a determining the operating characteristic of the internal combustion engine (1000) measuring device is determined. Procedure according to one of the Claims 3 to 5 , at which the predetermined amount by which the second quantity of fuel to be injected is changed in at least one repetition, depending on the target resolution of the corrected second assignment rule (Z2corr) and / or the measurement accuracy of one for detecting the operating parameter of the Internal combustion engine (1000) used measuring device is changed. Procedure according to one of the Claims 1 to 6 , in which the second assignment rule (Z2), in particular as a valve characteristic curve, is stored in a third memory unit (1013) in the control unit (1005). Procedure according to one of the Claims 1 to 7 , in which the corrected second assignment rule (Z2korr), in particular as a characteristic curve, is stored in the third memory unit (1013) in the control unit (1005). Procedure according to one of the Claims 1 to 8th , in which the corrected second assignment rule (Z2korr) replaces the second assignment rule (Z2). Method according to one of the preceding claims, with the following additional step: i) activation of the second injection valve (1045) of the internal combustion engine (1000) according to the second setpoint (S2) depending on the corrected second assignment rule (Z2Korr) from step h), in particular by interpolation. Procedure according to one of the Claims 2 to 10th , in which, when steps d) to h) are run through for the first time, the first value for the second quantity of fuel to be injected does not exceed a predetermined first threshold value. Procedure according to Claim 11 , in which, during the first passage through steps d) to h), the first value for the second quantity of fuel to be injected does not exceed the predetermined first threshold value, and steps d) to h) are repeated until the deviation (A) reaches a predetermined second Threshold value is exceeded, the second fuel quantity to be injected being increased by the predetermined amount in at least one repetition of step d). Procedure according to one of the Claims 2 to 10th , in which, when steps d) to h) are run through for the first time, the first value for the second fuel quantity to be injected exceeds the predetermined first threshold value. Procedure according to Claim 13 , in which, when steps d) to h) are run through for the first time, the first value for the second quantity of fuel to be injected exceeds the predetermined first threshold value, and steps d) to h) are repeated until the deviation (A) exceeds the predetermined second threshold value falls below, the second fuel quantity to be injected being reduced by the predetermined amount in at least one repetition of step d). Method according to one of the preceding claims, in which the resulting operating parameter of the internal combustion engine (1000) is the oxygen concentration of the exhaust gas of the internal combustion engine (1000). Method according to one of the preceding claims, in which a switchover between the determination of the first actual value (I1) of the resulting operating parameter of the internal combustion engine (1000) and the determination of the second actual value (12) of the resulting operating parameter of the internal combustion engine (1000) is dependent takes place from a variable characterizing a combustion cycle of the internal combustion engine, wherein a combustion cycle comprises at least one combustion. Method according to one of the preceding claims, in which the first actual value (I1) of the resulting operating parameter of the internal combustion engine (1000) and the second actual value (12) of the resulting operating parameter of the internal combustion engine (1000) during the combustion cycle of the internal combustion engine between a first one The point in time and a second point in time are recorded, the first point in time and the second point in time being determined as a function of the variable characterizing the combustion cycle of the internal combustion engine (1000). Procedure according to Claim 17 , in which the first and the second point in time are determined in such a way that the exhaust gas of the internal combustion engine (1000) from the combustion chamber (1075) after the combustion between the first point in time and the second point in time at a measuring device (1070) arranged in the internal combustion engine for detection the operating parameter of the internal combustion engine arrives. Procedure according to one of the Claims 16 to 18th , in which the quantity characterizing the combustion cycle of the internal combustion engine (1000) is a crankshaft angle and / or a rotational speed of the internal combustion engine (1000). Method according to one of the preceding claims, wherein the first control signal (205) of the first injection valve (1040) is a first electrical control period (t1), and the second control signal (225) of the second injection valve (1045) is a second electrical control period (t2) . Control unit for controlling an internal combustion engine (1000), set up to inject fuel for combustion into a combustion chamber (1075) by means of a first injection valve (1040) and by means of a second injection valve (1045), comprising: - a first specification unit (1010), suitably one to specify the first fuel quantity to be injected, a first control unit (1011) suitable for controlling the first injection valve (1040) according to a first assignment rule (Z1), the first assignment rule (Z1) assigning a first setpoint value (S1) to a first control signal (205), a second specification unit (1015), suitable for specifying a second fuel quantity to be injected, - a second control unit (1016), suitable for activating the second injection valve (1045) in accordance with a second assignment rule (Z2), the second assignment rule (Z2) for the second injector Fuel quantity assigns a second target value (S2) of a second control signal (225), - a determination unit (1020), suitable for determining a first actual value (I1) and a second actual value (12), the first actual value (11) by means of the first actual power injected from the combustion of the first injection valve (1040) Fuel quantity (q1) resulting operating parameter of the internal combustion engine (1000) on the one hand and the second actual value (12) by means of the first actual fuel quantity (q1) injected by the combustion of the control of the first injection valve (1040) and the control of the second Injection valve (1045) injected second actual fuel quantity (q2) resulting operating characteristic of the internal combustion engine (1000) is determined on the other hand, - a first storage unit (1025), which is designed to store the first actual value (I1), - a second storage unit (1022 ), which is designed to store the second actual value (12), - a comparison unit (1030), which is designed to deviate (A) between the first actual value (I1) and the second actual value (12) determine, - a second determination unit (1035), suitable for determining a corrected second assignment rule (Z2Korr) of the second injection valve (1045) by ch the second setpoint (S2) of the second control signal (225) is assigned to the deviation (A). Computer program that covers all steps of a method according to one of the Claims 1 to 20th executes when it runs on a computing device. Computer program product with program code, which is stored on a machine-readable carrier which carries out the method according to one of the Claims 1 to 20th performs when the program is run on a computer or control device.

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