EP1015749A1

EP1015749A1 - Method for operating an internal combustion engine

Info

Publication number: EP1015749A1
Application number: EP99919114A
Authority: EP
Inventors: Winfried Moser; Matthias Philipp; Dirk Mentgen; Michael Oder; Georg Mallebrein; Christian KÖHLER; Jürgen FÖRSTER
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-03-26
Filing date: 1999-03-24
Publication date: 2000-07-05
Anticipated expiration: 2019-03-24
Also published as: JP2002500725A; KR20010006156A; WO1999049200A1; DE19813378A1; DE59908415D1; US6302081B1; EP1015749B1

Abstract

The invention relates to an internal combustion engine (1), especially for a motor vehicle. The internal combustion engine (1) is provided with an injection valve (8) by means of which fuel can be injected directly into a combustion chamber (4) either in a first operating mode during a compression stage or in a second operating mode during a suction stage. The invention also provides for a control device (16) for switching between the two operating modes and for carrying out a control and/or adjustment, differently for each operating mode, of the operating variables influencing the actual torque of the internal combustion engine (1) in accordance with a set-point torque. A change in the actual torque occurring during switching is detected by the control device (16) and at least one of the operating parameters is influenced by the control device (16) in accordance with said change.

Description

Method for operating an internal combustion engine

State of the art

The invention relates to a method for operating a

Internal combustion engine, in particular of a motor vehicle, in which fuel is injected directly into a combustion chamber, either in a first operating mode during a compression phase or in a second operating mode during an intake phase, in which a switch is made between the two operating modes, and in which the actual torque of the internal combustion engine influencing operating variables depending on a target torque in the two operating modes are controlled and / or regulated differently. Furthermore, the invention relates to a

Internal combustion engine, in particular for a motor vehicle, with an injection valve, with which fuel is injected directly into a combustion chamber either in a first operating mode during a compression phase or in a second operating mode during an intake phase, and with a

Control unit for switching between the two operating modes and for different control and / or regulation in the two operating modes of the operating variables influencing the actual torque of the internal combustion engine as a function of a target torque.

Systems of this type for the direct injection of fuel into the combustion chamber of an internal combustion engine are generally known. It is a so-called stratified operation as the first operating mode and a so-called operating mode as the second Differentiated homogeneous operation. Stratified operation is used in particular for smaller loads, while homogether operation is used for larger loads applied to the internal combustion engine.

In stratified operation, the fuel is injected into the combustion chamber during the compression phase of the internal combustion engine in such a way that a cloud of fuel is in the immediate vicinity of a spark plug at the time of ignition. This injection can take place in different ways. So it is possible that the injected cloud of fuel is already during or immediately after the injection at the spark plug and is ignited by it. It is also possible that the injected fuel cloud is guided to the spark plug by a charge movement and only then ignited. In both combustion processes, there is no uniform fuel distribution, but a stratified charge.

The advantage of stratified operation is that the applied smaller loads can be carried out by the internal combustion engine with a very small amount of fuel. However, larger loads cannot be met by shift operation.

In the homogeneous operation provided for such larger loads, the fuel is injected during the intake phase of the internal combustion engine, so that swirling and thus distribution of the fuel in the combustion chamber can still take place easily. In this respect, homogeneous operation corresponds approximately to the operating mode of internal combustion engines, in which fuel is injected into the intake pipe in a conventional manner. If required, homo operation can also be used for smaller loads.

In stratified operation, the throttle valve in the intake pipe leading to the combustion chamber is opened wide and the combustion is essentially only by the Controlled and / or regulated fuel mass to be injected. In homogeneous operation, the throttle valve is opened or closed depending on the requested torque and the fuel mass to be injected is controlled and / or regulated depending on the air mass drawn in.

In both operating modes, that is to say in stratified operation and in homogeneous operation, the fuel mass to be injected is additionally dependent on a plurality of further operating variables with regard to

Fuel saving, exhaust gas reduction and the like optimal value controlled and / or regulated. The control and / or regulation is different in the two operating modes.

It is necessary to switch the internal combustion engine from shift operation to homogeneous operation and back again. While the throttle valve is wide open in stratified operation and the air is thus supplied largely unthrottled, the throttle valve is only partially open in homogeneous operation and thus reduces the supply of air. Especially when switching from stratified operation to homogeneous operation, the ability of the intake pipe leading to the combustion chamber to store air must be taken into account. If this is not taken into account, it can

Switching leads to an increase in the torque output by the internal combustion engine.

The object of the invention is to provide a method for operating an internal combustion engine with which an improved

Switching between the operating modes is possible.

This object is achieved according to the invention in a method of the type mentioned or in an internal combustion engine of the type mentioned in that a change in the actual torque is detected during a switching operation and that at least one of the operating variables is influenced as a function thereof. - 4 -

On the basis of the determination of changes in the actual torque during the switchover process, it is possible to recognize uneven running or a jerk during the switchover. After a jerk is detected, the uneven running can be counteracted by influencing the operating parameters. This makes it possible overall to avoid uneven running or jerking during the switchover from homogeneous operation to shift operation or vice versa. The switching processes between the two operating modes are thus improved, in particular with regard to increased smoothness and thus increased comfort.

In an advantageous embodiment of the invention, the actual moment is determined before and after a changeover process.

This is a particularly simple way to record the change in the actual torque.

In an advantageous development of the invention, the change in the actual torque as a function of the detected speed of the internal combustion engine is recognized. This ensures that a change in the actual torque and thus a jerk or the like can be detected with the help of the already existing speed sensor. Additional sensors or other additional components are therefore not required.

In an advantageous embodiment of the invention, rough running values are determined for the individual cylinders. From these rough running values, changes in the Is torque of the internal combustion engine can be concluded. With the help of the uneven running values, it is possible to detect speed fluctuations or a jerk in the internal combustion engine. The rough running values can be determined in different ways. It is thus possible to provide an uneven running sensor for measuring the uneven running values. The rough running values can also be derived, for example, from the speed of the internal combustion engine. It is essential that the uneven running values are a measure of torque differences - 5 -

between successive cylinders.

In an advantageous further development of the invention, at least one of the two operating modes in a corresponding operating point of the internal combustion engine

Operating variables influencing the actual torque are changed, and then at least one of the rough running values of the first operating mode is compared with at least one of the rough running values of the second operating mode. In the two operating modes, the internal combustion engine is therefore exposed to a change. The consequence of this change is determined in the form of a change in the uneven running values. This change in the uneven running values can be used to infer possible torque differences between the two operating modes. A possible jerk when switching between the two

Operating modes can thus be recognized in advance and avoided.

It is particularly advantageous if the operating variable is changed in a cylinder-specific manner such that the torque delivered by successive cylinders changes, but the total torque of all cylinders remains the same. The changes are therefore made on a cylinder-specific basis. This ensures that the total torque of all cylinders can be kept approximately constant. However, there are differences in the torque output between the cylinders, which can be used to identify possible speed fluctuations when switching between the two operating modes.

Furthermore, it is particularly advantageous if the torque given off by one of the cylinders is reduced and if the moments given off by the other cylinders are increased proportionately. This ensures that the total torque remains approximately constant and therefore no loss of comfort or the like arises for the user.

In an advantageous embodiment of the invention, an uneven running value is determined in each of the two operating modes, which are then compared with one another. there - 6 -

it is particularly expedient if a torque difference is determined from the comparison of the two uneven running values. This torque difference represents a static switching jerk, which is influenced by a corresponding influencing of the operating variables of the internal combustion engine

Minimization is counteracted.

In an advantageous development of the invention, the operating variables of the internal combustion engine are influenced as a function of the comparison. It is thus possible that, in the event of a discrepancy between the uneven running values of the first operating mode and the uneven running values of the second operating mode, operating variables of the internal combustion engine are influenced in such a way that this deviation is minimized or becomes zero. A possible jerk when switching between the two operating modes can thus be minimized or even reduced to zero.

In an advantageous development, the influencing of one of the operating variables is carried out adaptively. There is therefore a permanent correction to the resetting process. This makes it possible, for example, to compensate for changes in the internal combustion engine over its running time, in particular signs of wear and the like. It is also possible to compensate for deviations between different internal combustion engines of the same type during commissioning.

It is particularly advantageous if the calculation models of the two operating modes are adaptively matched to one another. This can be done in addition or alternatively to the adaptive influencing of operating variables of the internal combustion engine. This measure ensures that the static changeover pressure is reduced.

In a further advantageous development of the invention, the influencing of one of the operating variables is only carried out for the next changeover process. This ensures that the calculations according to the invention between two - 7 -

Switching operations can be carried out so that there is sufficient time for this.

It is particularly advantageous if, in the first operating mode, the injected fuel mass is influenced in particular in the sense of an increase. It is also advantageous if, in the second operating mode, the ignition angle or the ignition timing is influenced, in particular in the sense of a retardation. Through these measures, it is possible to detect a running irregularity during the

Switching process to influence the actual torque of the internal combustion engine and thus reduce the uneven running. In particular, these measures bring the two operating modes closer to one another at the time of the changeover.

Of particular importance is the implementation of the method according to the invention in the form of a control element which is provided for a control device of an internal combustion engine, in particular a motor vehicle. A program is stored on the control element, which is executable on a computing device, in particular on a microprocessor, and is suitable for executing the method according to the invention. In this case, the invention is thus implemented by a program stored on the control element, so that this control element provided with the program represents the invention in the same way as the method, for the execution of which the program is suitable. In particular, an electrical storage medium, for example a read-only memory, can be used as the control element.

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are shown in the figures of the drawing. All of the described or illustrated features, alone or in any combination, form the subject matter of the invention, regardless of their summary in the patent claims or their relationship and regardless of their - 8th -

Formulation or representation in the description or in the drawing.

FIG. 1 shows a schematic block diagram of an exemplary embodiment of an internal combustion engine of a motor vehicle,

FIG. 2 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for operating the internal combustion engine of FIG. 1, FIG. 3 shows a schematic time diagram of FIG

Signals of the internal combustion engine of Figure 1 when performing the method of Figure 2,

FIG. 4 shows a schematic time diagram of signals of the internal combustion engine of FIG. 1 when carrying out one which is opposite to the method of FIG. 2

Process,

FIG. 5 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for switching according to FIGS. 2 to 4, and FIG. 6 shows a schematic time diagram of FIG

Uneven running values of a cylinder of the internal combustion engine of FIG. 1.

FIG. 1 shows an internal combustion engine 1 in which a piston 2 can be moved back and forth in a cylinder 3. The cylinder 3 is provided with a combustion chamber 4, to which an intake pipe 6 and an exhaust pipe 7 are connected via valves 5. Furthermore, the combustion chamber 4 has an injection valve 8 that can be controlled with a signal TI and one that can be controlled with a signal ZW

Spark plug 9 assigned.

The intake pipe 6 is provided with an air mass sensor 10 and the exhaust pipe 7 can be provided with a lambda sensor 11. The air mass sensor 10 measures the air mass of the fresh air supplied to the intake pipe 6 and generates a signal LM as a function thereof. The lambda sensor 11 measures the oxygen content of the exhaust gas in the exhaust pipe 7 and generates a signal as a function thereof 9 -

A throttle valve 12 is accommodated in the intake pipe 6, the rotational position of which can be set by means of a signal DK.

In a first operating mode, the stratified operation of the internal combustion engine 1, the throttle valve 12 is opened wide. The fuel is injected from the injection valve 8 into the combustion chamber 4 during a compression phase caused by the piston 2, specifically locally in the immediate vicinity of the spark plug 9 and at a suitable time before the ignition point. Then the fuel is ignited with the aid of the spark plug 9, so that the piston 2 is driven in the now following working phase by the expansion of the ignited fuel.

In a second operating mode, the homogeneous operation of the internal combustion engine 1, the throttle valve 12 is partially opened or closed depending on the desired air mass supplied. The fuel is injected into the combustion chamber 4 by the injection valve 8 during an induction phase caused by the piston 2. The injected fuel is swirled by the air drawn in at the same time and is thus distributed substantially uniformly in the combustion chamber 4. Then the fuel / air mixture during the

Compression phase compressed to then be ignited by the spark plug 9. The piston 2 is driven by the expansion of the ignited fuel.

In shift operation as well as in homogeneous operation, the driven piston sets a crankshaft 14 into a rotary movement, via which the wheels of the motor vehicle are ultimately driven. A speed sensor 15 is assigned to the crankshaft 14 and generates a signal N as a function of the rotary movement of the crankshaft 14.

The fuel mass injected into the combustion chamber 4 by the injection valve 8 in stratified operation and in homogeneous operation is in particular controlled by a control unit 16 - 10 -

controlled and / or regulated with a view to low fuel consumption and / or low pollutant development. For this purpose, the control device 16 is provided with a microprocessor which has stored a program in a storage medium, in particular in a read-only memory, which is suitable for carrying out the control and / or regulation mentioned.

The control device 16 is acted upon by input signals, the operating variables of the measured by means of sensors

Represent internal combustion engine. For example, the control unit 16 is connected to the air mass sensor 10, the lambda sensor 11 and the speed sensor 15. Furthermore, the control unit 16 is connected to an accelerator pedal sensor 17 which generates a signal FP which indicates the position of an accelerator pedal which can be actuated by a driver and thus the torque requested by the driver. The control unit 16 generates output signals with which the behavior of the internal combustion engine can be influenced via actuators in accordance with the desired control and / or regulation. For example, the control unit 16 is connected to the injection valve 8, the spark plug 9 and the throttle valve 12 and generates the signals TI, ZW and DK required to control them.

The control device 16 carries out the method described below with reference to FIGS. 2 and 3 for switching from shift operation to homogeneous operation. The blocks shown in FIG. 2 represent functions of the method that are implemented, for example, in the form of software modules or the like in control unit 16.

A block 21 in FIG. 2 assumes that the internal combustion engine 1 is in a stationary position

Shift operation is located. In block 22, a transition to homogeneous operation is then requested, for example, on the basis of an acceleration of the motor vehicle desired by the driver. The time of the request - 11 -

of the homogeneous operation can also be seen from FIG. 3.

This is followed by debouncing by means of blocks 23, 24, with which a short successive switching back and forth between the shift and the homogeneous operation is prevented. If homogeneous operation is enabled, the transition from shift operation to homogeneous operation is started by block 25. The point in time at which the changeover process begins is identified in FIG. 3 by reference numeral 40.

At the time 40 mentioned, the throttle valve 12 is controlled by means of a block 26 from its state wdksch, which is fully open in stratified operation, to an at least partially open or closed state wdkhom for homogeneous operation. The rotational position of the throttle valve 12 in homogeneous operation is in particular aimed at a stoichiometric fuel / air mixture, that is to say = 1, and also depends on e.g. the requested torque and / or the speed N of the

Internal combustion engine 1 and the like. However, it is also possible to set the fuel / air mixture rich or lean, i.e. to select <1 or> 1.

By adjusting the throttle valve 12 is the

Internal combustion engine 1 from the stationary stratified operation into an unsteady stratified operation. In this operating state, the air mass supplied to the combustion chamber 4 slowly drops from a filling rlsch during stratified operation to smaller fillings. This can be seen from FIG. 3. The air mass rl supplied to the combustion chamber 4 or its filling is determined by the control unit 16, inter alia, from the signal LM of the air mass sensor 10. According to a block 27, the internal combustion engine 1 continues to be operated in shift operation.

Then, a block 28 of FIG. 2 is used to switch over to non-stationary homogeneous operation. This is in the - 12 -

Figure 3 at a time 41 the case.

According to a block 29, the fuel mass rk injected into the combustion chamber 4 is controlled and / or regulated as a function of the air mass rl supplied to the combustion chamber 4 in such a way that in particular a stoichiometric fuel / air mixture arises, that is

= 1. However, it is also possible to set the fuel / air mixture in a range of 0.7 1.5.

The fuel mass rk influenced in this way has the consequence that — at least for a certain period of time — the torque Md output by the internal combustion engine 1 would increase. This is compensated for by the fact that at time 41, i.e. when switching to homogeneous operation, the ignition angle ZW is adjusted based on the value zwsch in such a way that the torque Md given maintains a setpoint torque resulting from, among other things, the requested torque and thus remains about constant.

For this purpose, the fuel mass rk is determined from the air mass rl supplied to the combustion chamber 4 on the basis of a stoichiometric fuel / air mixture. Furthermore, the ignition angle ZW is adjusted in the direction of a retarded ignition as a function of the target torque mdsoll. With regard to this late adjustment, there is still a certain deviation from normal homogeneous operation, with which the excess air supply and the resulting excess torque generated by the internal combustion engine 1 are temporarily destroyed.

In a block 30 it is checked whether the air mass rl supplied to the combustion chamber 4 has finally fallen to the filling that belongs to a stationary homogeneous operation with a stoichiometric fuel / air mixture. If this is not yet the case, the process continues in a loop via block 29. However, if this is the case, then the internal combustion engine 1 is operated in stationary homogeneous operation without an ignition angle adjustment by means of the - 13 -

Blocks 31 continued to operate. In FIG. 3, this is the case at a point in time identified by reference number 42.

In this stationary homogeneous operation, the air mass supplied to the combustion chamber 4 corresponds to the filling rlhom for the homogeneous operation and the ignition angle zwhom for the spark plug 9 also corresponds to that for the homogeneous operation. The same applies to the rotational position wdkhom of the throttle valve 12.

In FIG. 3, the stationary stratified operation is identified as area A, the non-stationary stratified operation as area B, the unsteady homogeneous operation as area C and the stationary homogeneous operation as area D.

FIG. 4 shows a switchover from homogeneous operation to shift operation. A steady-state homogeneous operation is assumed, in which, for example, the operating variables of the internal combustion engine 1 are to be used for a stationary shift operation.

The switchover to shift operation is initiated by control unit 16 by withdrawing the requirement of homogeneous operation. After debouncing, the switchover to shift operation is released and throttle valve 12 is controlled into the rotational position which is provided for shift operation. This is a rotational position in which the throttle valve 12 is largely open. This is illustrated by the transition from wdkhom to wdksch in FIG. 4.

It is possible that this transition is further processed by the control unit 16 without or with consideration of a throttle valve overshoot. This is shown in FIG. 4 by solid or dashed lines.

The opening of the throttle valve 12 has the consequence that the air mass rl supplied to the combustion chamber 4 increases. This goes in - 14 -

4 from the course of rlhom. This is followed by the switchover from the unsteady homogeneous operation described to an unsteady shift operation. This is the case in FIG. 4 at time 43.

Before switching to stratified operation, the increasing air mass supplied to the combustion chamber 4 is compensated for by the fact that the injected fuel mass rk is increased and the ignition angle ZW is adjusted late. This results in FIG. 4 from the course of rkhom and zwhom.

After switching over to shift operation, the injected fuel mass rk is set to the value rksch for shift operation. The same applies to the ignition angle ZW, which is set to the value between stratified operation.

4 shows the stationary homogeneous operation as area A, the non-stationary homogeneous operation as area B, the unsteady shift operation as area C and the stationary

Shift operation marked as area D.

FIG. 5 shows a method that can be used during the switchover from shift operation to homogeneous operation according to FIGS. 2 and 3. The method serves to detect changes in the torque of the internal combustion engine 1, that is to say changes in the actual torque Md emitted during the switching process. The blocks shown in FIG. 5 represent functions of the method, for example in the form of

Software modules or the like are implemented in the control unit 16.

In block 51, a steady-state shift operation is assumed, in which the internal combustion engine 1 is located and in which the internal combustion engine 1 has a specific operating point that can be understood by the control device 16.

At this operating point of the shift operation is in one - 15 -

Block 52 made a reduction in the fuel mass rk supplied to the cylinder x in such a way that the actual torque Md of the internal combustion engine itself would decrease by, for example, 10%. At the same time, however, the fuel mass rk supplied to the other cylinders is increased such that the actual torque Md of the internal combustion engine 1 would increase by 10%. Overall, this has the consequence that the actual torque Md of the internal combustion engine 1 does not change, so that the total torque from all cylinders remains approximately constant. In this way, the internal combustion engine

1, a so-called torque pattern is impressed, which on the one hand results in a change in the torque output of the individual cylinders 3, but does not change the total torque of all cylinders 3 overall.

It is expressly pointed out that other possibilities are also conceivable with which the internal combustion engine 1 can be influenced. It is essential that the given moments of successive cylinders are changed.

Uneven running values of the individual cylinders 3 are then determined in a block 53. According to the torque pattern, these are so-called uneven running patterns.

These rough running values can be any values that characterize the rough running or smooth running of the internal combustion engine 1. For example, it is possible to assign a sensor to internal combustion engine 1, which detects the uneven running or smooth running of internal combustion engine 1. It is also possible for the uneven running of the internal combustion engine 1 to be determined from other, in particular already existing, operating variables of the internal combustion engine 1. In particular, it is possible for the uneven running to be calculated from the speed N of the internal combustion engine 1.

The uneven running or smooth running of the internal combustion engine 1 represents a measure of changes in the actual torque Md - 16 -

Internal combustion engine 1. In particular, the uneven running or smooth running is a measure of torque differences between successively fired cylinders 3 of the internal combustion engine 1. For this purpose, it is possible that the uneven running or smooth running can be assigned to the individual cylinders 3 of the internal combustion engine 1.

A method for determining the uneven running or smooth running of the internal combustion engine 1 is explained below. It is expressly pointed out that this method described is only of an exemplary nature and can be replaced and / or supplemented by any other method for determining the uneven running or smooth running.

To determine the uneven running of the internal combustion engine 1, segment times ts are measured during the operation of the internal combustion engine 1. A segment time ts is measured for each combustion. Each combustion is given a number n and the associated segment time is marked accordingly with ts (n). For example, a crankshaft angle of 360 degrees divided by half the number of cylinders is selected as the segment and assigned to each of the cylinders 3 of the internal combustion engine 1. In particular, it is possible to arrange the segment symmetrically to the top dead center of the respective cylinder 3.

The combustion-dependent segment times ts (n) are detected, for example, with the aid of a sensor which measures the time period for the respective segment to move past a reference point. The sensor can in particular be the speed sensor 15. The segment times ts (n) measured by the sensor simultaneously represent speed information from which the course of the speed and thus also speed fluctuations can be derived for the respective cylinder 3.

By means of comparison and, if necessary, adaptation functions, it is possible to determine system-related speed fluctuations and to compensate or to compensate for the uneven running or - 17 -

to be disregarded. This can involve manufacturing tolerances or vibrations or the like, for example. Segment times tsk (n) compensated in this way are essentially only dependent on cylinder-specific torque fluctuations.

The rough running value is calculated from these compensated segment times tsk (n), for example as follows:

lut (n) = (tsk (n + l) - tsk (n) / tsk (n) ³ ).

By assigning the rough-running values lut (n) numbered according to the burns n to the z cylinders 3 of the internal combustion engine 1, for example, j individual cylinder cycles are created for each work cycle

Uneven running values lut (z, j). These rough running values lut (z, j) can be filtered using appropriate algorithms. For example, it is possible to carry out low-pass filtering in order to suppress stochastic interference. Filtered, cylinder-specific rough running values (z, j) represent the measure for torque differences between successively fired cylinders 3 of the internal combustion engine 1.

Are in block 53, for example, after that

Uneven running values lut (n) and / or lut (z, j) and / or flood (z, j) have been determined, these values are used in the method described below. As already mentioned, uneven running values determined differently can also be used accordingly in the method described below.

As mentioned, the uneven running values ultimately used relate to a specific operating point of shift operation and are therefore referred to in FIG. 5 as LUT _S.

At a later point in time, the internal combustion engine 1 is in one of the aforementioned operating points operating point of homogeneous operation corresponding to the shift operation. This is recognized by the control device 16, which is indicated in FIG. 5 by the arrow 54. The internal combustion engine 1 is thus located in block 55 at the corresponding operating point of stationary homogeneous operation.

If this is the case, the same torque pattern of the internal combustion engine 1 is impressed in a block 56 as was impressed in the block 52 at the corresponding operating point of the stationary stratified operation. While the fuel mass rk has been adjusted in block 52 for this purpose, the ignition angle ZW or the ignition timing can now be changed in block 56.

Uneven running values of the individual cylinders 3 are determined in a block 57. According to the torque pattern, these are so-called uneven running patterns.

These rough running values are determined in the same way as has already been explained in connection with block 53. If uneven running values lut (n) and / or lut (z, j) and / or flood (z, j) have been determined, these values are used further in the method described below. As already mentioned, uneven running values determined differently can also be used accordingly in the method described below.

As mentioned, the uneven running values ultimately used relate to a specific operating point of the

Homogeneous operation and are therefore referred to in Figure 5 as LUT _h .

The uneven running values LUT _S and LUT _h can also be determined in the reverse order, so that blocks 55, 56 and 57 are first run through and then blocks 51, 52 and 53 are run through. In this case, arrow 54 extends from the exit of block 57 to the entrance of block 51. - 19 -

If the uneven running values LUT _S and LUT _{h are} present, the method is continued with a block 59. This is indicated by the two arrows 58.

In block 59, the two uneven running values LUT _S and

LUT _{h is} a measure of a torque difference Md. This is explained below using FIG. 6.

FIG. 6 shows a time diagram of the two rough running values LUT _S and LUT _{h of} a cylinder 3.

It can be seen that the uneven running value LUT _S differs in size from the uneven running value LUT _h . This difference is based on different moments that the internal combustion engine 1 in the corresponding operating points in

Shift operation and generated in homogeneous operation. The difference therefore represents a measure of the torque difference Md between the two operating modes. The following applies here:

Md = k * (LUT _ε - LUT,

with k = proportionality factor dependent on the internal combustion engine.

This torque difference Md is determined in block 59 by the

Control unit 16 determined. It may be necessary to take into account further operating variables of the internal combustion engine 1. It may also be necessary to adapt this calculation over the operating period of the internal combustion engine 1.

In a subsequent block 60, the internal combustion engine 1 is influenced in such a way that the torque difference Md becomes as small as possible or even zero. The operating variables of the internal combustion engine 1 are thus changed such that the torque difference Md becomes smaller.

For this purpose, the operating parameters in one of the two operating modes or, if necessary, also in both - 20 -

Operating modes affected. In shift operation, for example, the fuel mass rk supplied to the combustion chamber 4 can be changed. In homogeneous operation, for example, the retardation of the ignition angle ZW or the ignition timing can be changed.

If changes in the actual torque Md of the internal combustion engine 1, that is to say torque differences Md during the switchover process, have been detected using the method in FIG. 5, then, as described, in block 60

Countermeasures initiated. These countermeasures involve changes in the operating variables of internal combustion engine 1, with which the actual torque Md of internal combustion engine 1 is influenced.

If changes in torque are detected between the areas A and D, the fuel mass rk to be injected into the combustion chamber 4 is reduced or increased in the area A in such a way that the changes in torque found become less. Alternatively or additionally, it is possible to adjust the air mass rl and / or the fuel mass rk and / or, if necessary, the ignition angle ZW or the ignition timing in the event of detected torque changes between the areas A and D in homogeneous operation, so that the torque changes are reduced. The determined torque changes between the areas A and D are static torque changes which can be permanently corrected by adaptive changes in the respective operating variables.

In the event of a changeover process from homogeneous operation to stratified operation according to FIG. 4, the air mass rl or the filling and / or the fuel mass rk are adjusted when torque changes are detected in areas A and D, so that the torque changes are reduced. Additively or alternatively, it is possible to reduce or increase the fuel mass rk to be injected into the combustion chamber 4 in the event of determined torque changes in the areas A and D such that the determined - 21 -

Torque changes are less. The determined torque changes between the areas A and D are static torque changes which can be permanently corrected by adaptive changes in the respective operating variables.

The above-mentioned influencing of operating variables of the internal combustion engine 1 to compensate for uneven running or jerking during a switchover process can be carried out immediately, so that there may still be an effect during the current Umsehal process. However, it is also possible that the influencing is carried out in such a way that an effect is only present at the next changeover process.

With adaptive measures, it is possible that the operating variables of the respective operating mode are changed on the basis of a single determination of the torque change Md for a specific operating point. It is also possible that torque changes from several operating points or from all operating points are used.

Claims

22 Patent claims

1. Method for operating an internal combustion engine (1), in particular a motor vehicle, in which fuel is injected directly into a combustion chamber (4), either in a first operating mode during a compression phase or in a second operating mode, in which the switch is made between the two operating modes and where the actual torque (Md) is the

Operating variables influencing the internal combustion engine (1) are controlled and / or regulated differently in the two operating modes as a function of a target torque (mdsoll), characterized in that a change in the actual torque (Md) is detected during a changeover process

(Fig. 5), and that, depending on this, at least one of the operating variables is influenced (60).

2. The method according to claim 1, characterized in that the actual moment (Md) is determined before and after a UmsehaltVorgangs.

3. The method according to any one of claims 1 or 2, characterized in that the change in the actual torque (Md) as a function of the detected speed (N) of the internal combustion engine is detected (53, 57).

4. The method according to any one of claims 1 to 3, characterized in that uneven running values for the individual cylinders (3) are recognized (53, 57).

5. The method according to claim 4, characterized in that in the two operating modes in a mutually corresponding operating point of the internal combustion engine (1) at least one of - 23 -

the actual method is changed according to operating variables influencing torque (Md) (52, 56), and that at least one of the rough running values of the first operating mode is then compared with at least one of the rough running values of the second operating mode (59).

6. The method according to claim 5, characterized in that the operating size is changed cylinder-specifically in such a way (52, 56) that the output torque of successive cylinders (3) changes, but that the total torque of all cylinders (3) remains the same.

7. The method according to claim 6, characterized in that the torque given by one of the cylinders (x) is reduced, and that the moments given off by the other cylinders (3) are increased proportionately.

8. The method according to any one of claims 4 to 7, characterized in that an uneven running value (LUT _S , LUT _n ) is detected in each of the two operating modes, which are then compared with one another (59).

9. The method according to claim 8, characterized in that from the comparison (59) of the two uneven running values (LUT _S , LUT, a torque difference (ΔMd) is detected.

10 The method according to any one of claims 5 to 9, characterized in that the operating variables of the internal combustion engine (1) are influenced as a function of the comparison (59).

11 Method according to one of the preceding claims, characterized in that the influencing of one of the operating variables is carried out adaptively.

12 Method according to one of the preceding claims, characterized in that the calculation models of the two operating modes are adaptively adapted to one another. 24

13. The method according to any one of the preceding claims, characterized in that the influencing of one of the operating variables is carried out only for the next conversion process.

14. The method according to any one of the preceding claims, characterized in that in the first operating mode, the injected fuel mass (rk) is influenced in particular in the sense of an increase.

15. The method according to any one of the preceding claims, characterized in that the air mass in the second operating mode

(rl) and / or the fuel mass (rk) can be influenced.

16. Control element, in particular read-only memory, for a control device (16) of an internal combustion engine (1), in particular a motor vehicle, on which a program is stored which can be run on a computing device, in particular on a microprocessor, and for executing a

Method according to one of claims 1 to 15 is suitable.

17. Internal combustion engine (1), in particular for a motor vehicle, with an injection valve (8), with which fuel can be injected directly into a combustion chamber (4) either in a first operating mode during a compression phase or in a second operating mode, and with a Control device (16) for switching between the two operating modes and for different control and / or regulation in the two operating modes of the operating variables influencing the actual torque (Md) of the internal combustion engine (1) as a function of a target torque (mdsoll), characterized that a change in the actual torque (Md) during a switchover process can be determined by the control unit (16) (FIG. 5), and that at least one of the operating variables can be influenced by the control unit (16) (60).