EP0995026A1

EP0995026A1 - Method for operating an internal combustion engine

Info

Publication number: EP0995026A1
Application number: EP99922072A
Authority: EP
Inventors: Winfried Moser; Matthias Philipp; Dirk Mentgen; Michael Oder; Georg Mallebrein; Christian Koehler; Juergen Foerster
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-03-26
Filing date: 1999-03-24
Publication date: 2000-04-26
Anticipated expiration: 2019-03-24
Also published as: US6446596B1; JP2002500724A; WO1999049199A1; DE19813382A1; EP0995026B1; DE59906656D1

Abstract

The invention relates to an internal combustion engine (1), especially for a motor vehicle. The international combustion engine (1) has 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, which is different in 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 an internal combustion engine, in particular a motor vehicle, in which fuel is injected directly into a combustion chamber, in which a switch is made between the two operating modes, either in a first operating mode during a compression phase or in a second operating mode, and in The operating variables influencing the actual torque of the internal combustion engine are controlled and / or regulated differently in dependence on a target torque in the two operating modes. Furthermore, the invention relates to an internal combustion engine, in particular for a motor vehicle, with an injection valve, with which fuel can be 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 both

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.

Such systems for the direct injection of fuel into the combustion chamber of an internal combustion engine are general known. A distinction is made between a so-called stratified operation as the first operating mode and a so-called homogeneous operation as the second operating mode. Stratified operation is used in particular for smaller loads, while homogeneous 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 fuel oil 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 necessary, even with smaller loads, homogeneous operation be used.

In stratified operation, the throttle valve in the intake pipe leading to the combustion chamber is opened wide and the combustion is essentially only controlled and / or regulated by the 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 shift operation and in homogeneous operation, the fuel mass to be injected is controlled and / or regulated as a function of a plurality of further operating variables to an optimum value with regard to fuel savings, exhaust gas reduction and the like. 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, the switchover can lead 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 a improved switching between the operating modes is possible.

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

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 change in the actual torque is determined when switching from the first to the second operating mode. This is a simple but effective way to detect changes in the actual torque in a quasi-stationary manner.

In a further advantageous embodiment of the

According to the invention, the change in the actual torque is determined in particular in succession with different fillings of the combustion chamber. In this way, the dynamic changeover jerk is recognized quasi-steadily in the dynamic operation of the internal combustion engine. Thereupon this changeover jerk can be caused by a dynamic influencing of the operating variables of the Internal combustion engine can be counteracted in the sense of minimization.

In an advantageous development of the invention, the change in the actual torque is determined as a function of the detected speed of the internal combustion engine. 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 uneven running values, changes in the actual 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 represent a measure of torque differences between successive cylinders.

In an advantageous development of the invention, only one of the cylinders is switched over first, and then at least one of the uneven running values of the switched cylinder is switched over with at least one of the

Uneven running values of at least one of the other cylinders are compared. This makes it possible to determine whether there is a torque difference between the switched cylinder and the cylinders that have not yet switched. In this way it can be recognized whether a between the two operating modes between which to switch - 6 -

Torque difference and thus a jerk can occur.

It is particularly advantageous if the other cylinders are switched or not switched depending on the comparison. If the uneven running values of the switched cylinder differ significantly from the uneven running values of the non-switched cylinder, switching can be prevented in order to reliably avoid jerking in the internal combustion engine. However, if there is no significant deviation, the other cylinders can also be switched to the other operating mode. In this case, the internal combustion engine is not expected to jerk due to the small difference in the uneven running values.

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, if a discrepancy in the uneven running values of the switched cylinder is determined by the uneven running values of the other cylinders, operating variables of the internal combustion engine are influenced in such a way that this deviation is minimized or becomes zero. The changeover that has started can be terminated in order to avoid jerking in the internal combustion engine. However, it is also possible to carry out the switchover completely, so that the influencing of the operating variables only becomes effective during subsequent switchovers.

In an advantageous development, the influencing of one of the operating variables is carried out adaptively. There is therefore a permanent correction of the switching operation. 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 deviate - 7 -

balance between different internal combustion engines of the same type during commissioning.

In a further advantageous development of the invention, the influencing of one of the operating variables is only carried out for the next switching operation. It is thus achieved that the calculations according to the invention can be carried out between two switching processes, 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, in particular in the sense of a

Late adjustment is affected. These measures make it possible to influence the actual torque of the internal combustion engine when the uneven running is detected and thus to reduce uneven running. In particular, these two measures

Operating modes approximated at the changeover time.

Of particular importance is the implementation of the method according to the invention in the form of a control element for a control device

Internal combustion engine, in particular a motor vehicle, is provided. 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 therefore 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. An electrical storage medium can in particular be used as the control element Use, for example, a read-only memory.

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 features described or illustrated, individually or in any combination, form the subject matter of the invention, regardless of their summary in the patent claims or their dependency, and regardless of their formulation or representation in the description or in the drawing.

Figure 1 shows a schematic block diagram of an embodiment of an inventive

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 signals of the internal combustion engine of FIG. 1 when the method according to FIG. 2 is carried out, FIG. 4 shows a schematic time diagram of signals of the internal combustion engine of FIG

2, and FIG. 5 shows a schematic flow diagram of an exemplary embodiment of a method according to the invention for the switchover according to FIGS. 2 and 3.

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, on which a suction pipe 6 and a via valves 5 Exhaust pipe 7 are connected. Furthermore, an injection valve 8 that can be controlled with a signal TI and a spark plug 9 that can be controlled with a signal ZW are assigned to the combustion chamber 4.

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 λ as a function thereof.

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 intake phase caused by the piston 2 - 10 -

injected. 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. The fuel / air mixture is then compressed during the compression phase in order 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 turns a crankshaft 14 into a

Rotational movement offset, 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 mode and in homogeneous mode is controlled and / or regulated by a control unit 16, in particular with regard 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 which represent operating variables of the internal combustion engine measured by means of sensors. 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 over - 11 -

Actuators the behavior of the internal combustion engine can be influenced according to 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.

In FIG. 2, it is assumed in a block 21 that the internal combustion engine 1 is in a stationary stratified operation. In a block 22, for example, a transition into one is made on the basis of an acceleration of the motor vehicle desired by the driver

Homogeneous operation requested. The time of the request for homogeneous operation can also be seen in 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 switching process begins is identified in FIG. 3 by the reference symbol 40.

At the point in time 40 mentioned, the throttle valve 12 is changed from its state wdksch fully open in stratified operation to an at least partially opened or closed state wdkhom for by means of a block 26 - 12 -

controlled homogeneous operation. The rotational position of the throttle valve 12 in homogeneous operation is aimed at a stoichiometric fuel / air mixture, i.e. at λ = 1, and also depends on e.g. the requested torque and / or the speed N of the internal combustion engine 1 and the like.

By adjusting the throttle valve 12, the internal combustion engine 1 changes from stationary stratified operation to unsteady-state stratified operation. In this

In the operating state, the air mass supplied to the combustion chamber 4 slowly drops from a filling rlsch during shift 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 the case in FIG. 3 at a time 41.

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 is formed, that is to say λ = 1. However, it is also possible that

Set fuel / air mixture rich or lean, i.e. choose λ> 1 or λ <1.

The fuel mass rk influenced in this way has the consequence that - at least for a certain period of time - - 13 -

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 from the

Combustion chamber 4 supplied air mass rl determined on the basis of a stoichiometric fuel / air mixture. Furthermore, the ignition angle ZW is adjusted in the direction of a retarded ignition depending on 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. If this is the case, however, the internal combustion engine 1 continues to be operated in the stationary homogeneous operation without an ignition angle adjustment by means of the block 31. 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. - 14 -

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 can be seen in FIG. 4 from the course of rlhom. Then the switchover from the transient described - 15 -

Homogeneous operation in a transient 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.

In FIG. 4, stationary homogeneous operation is identified as area A, unsteady homogeneous operation as area B, unsteady shift operation as area C and stationary shift operation 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 procedure serves to change the torque

Internal combustion engine 1, that is to say changes in the delivered actual torque Md during the switching process. The blocks shown in FIG. 5 represent functions of the method that are implemented, for example, in the form of software modules or the like in control unit 16.

According to a block 51, it is assumed that the internal combustion engine 1 is in a stationary stratified operation. In a block 52, the switching process from shift operation to - 16 -

Homogeneous operation started.

The method described below for recognizing and minimizing a dynamically occurring changeover jerk is carried out sequentially in each case in a quasi-stationary manner with different fillings rllimit.

For this purpose, a limit value R1 limit for the filling of the combustion chamber 4 is selected in a block 53 such that this limit value R1 limit can be used both in stratified operation and in homogeneous operation.

According to a block 54, the throttle valve 12 is closed. The consequence of this is that the air mass r1 supplied to the combustion chamber and thus the filling in the combustion chamber are reduced. The pressure ps in the intake pipe 6 of the internal combustion engine 1, from which the charge rl can be derived, also decreases due to the closing of the throttle valve 12. Independently of these changes, the internal combustion engine 1 continues to be operated according to block 55 in stratified operation.

A block 56 checks whether the filling rl in the combustion chamber 4 has fallen to the limit value rl limit, that is to say whether rl has become <rl limit. If this is not yet the case, the method is continued with block 54, in particular with the further operation of internal combustion engine 1 in shift operation in accordance with block 55.

If rl <rl limit has become, ie the charge rl in the combustion chamber 4 of the internal combustion engine 1 has reached the limit value rl limit, then the pressure ps in the intake pipe 6 is then kept approximately constant in accordance with a block 57. This can be done, for example, by suitably influencing the oo 43 o 1 o U d CQ d Φ 4J -rl Φ Φ d 4-1

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H TJ Φ Φ C rH \, CQ rβ SH 4 H υ TJ TJ in SH 4H ε Φ -rl SH Φ SH

TJ "2 TJ Φ 43 d d Φ rH cn SH Φ JH m d d 4H SH ε J φ -H -H CQ CQ Φ J Φ Φ

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43 r-H Φ CQ rH SH SH -rH ε 4J J d d ε = 0 -

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SH d 43 SH ^ 43 4-> -rl SH d 5 Φ TJ X SH X rβ Φ 43 Φ •

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4 d Φ P JH JH 4H d -H Φ SH -H 4- ⁾ TJ d 4- ⁾ CQ TJ JH JH Di υ Φ -H -H 43 d CQ Φ £ • 43 ddd 43 T Φ Φ d rβ Φ -H JH Φ Φ φ ^• H -H Φ φ U d SH Φ d JH 4-) CJ TJ rβ fβ J JH Φ> N φ SH 4-) d SH 0 £ TJ to CQ P rH ^• ä d

4-) Φ rH 4-> Φ JH CQ PX CQ Φ -n 4-> ε Ü rH TJ 4 d Dl φ rβ d TJ 4- ⁾ φ Φ TJ Φ Φ TJ rβ TJ Φ d cn 43 SH Φ N -. d CQ • -r- 1

Φ CQ N d 4 43 d JH d ε -H TJ Φ Φ o: fβ 0 ε dd 4-) Φ Φ dd 4J ε ro -H d TJ Di dd Φ Φ 4-> CQ Φ Φ ε to VD S Φ rβ - QQ Di rH φ d -H

0 -H JH d: ⁽ β CQ TJ TJ 4H 43 43 Cn n Φ Di & CQ rβ -H d Φ rH φ ε d - Φ 0 d rH Φ 4J JH rβ Φ Φ CQ ε

The d CQ ro 4-> 4H rH d T rH J rβ

43 JH CJ Φ rH SH CQ rβ tn Φ JH -H J • to rH d N JH -H rβ d Φ TJ

Φ Φ Φ d tn 4-> Φ Φ 43 d 5 X SH JH d <0 rH 4J CQ d Φ φ X fβ 4-> JH

SH T ^■ 5 Φ d 4-> -H dd 4J -H Φ Φ> 43 H d JH φ 5 43 CQ = d TJ

P d N TJ N -H H TJ SH ε 4 d Φ 5 CQ cn • rβ φ Φ 4-) CQ φ 4H ε d

-H Φ ε N Φ PQ CQ -H 4-> rH N Φ ε TJ -H JH> o LΠ _^ - _^ d

JH rH ε Φ rH Φ C3 4J -H d SH -H Φ JH φ Φ d d cn d Φ 0 CQ H Cj d.

= d> ι Φ 43 w d rβ i - = rβ PQ CQ Φ ε = 0 d X rβ -H Φ -H N CQ CQ d Φ rH TJ

4H N CQ d Φ -H TJ rβ CQ Cn φ 43 X 43 d JH 43 to rH - d Φ φ JH CQ d 43 d

1 Φ JH d JH XI JH Φ JH JH J fβ cn Φ u -H Φ υ 1 d φ TJ w 0 4-> Φ rβ -μ

<ϊ3 d -H 4H ^• H d CJ • ». fβ PQ Φ Φ P Di -H 5 TJ QQN Φ to CQ JN CQ co rβ Φ J d 43 N CQ d Xi TJ TJ CQ d Φ dd rβ rβ ε d ε dd X. r— | 2 4J fβ CJ rβ Φ U JH JH d • 4 NN Φ -H ε TJ d Cn CQ Φ Φ Φ φ CQ Φ JH φ d, -3 CQ d ε CQ d Φ Φ φ dd rH rH 4- ⁾ Φ Φ Φ Cn J CQ 4- ⁾ d JH fβ jd TJ N fβ Φ 4- ⁾ φ d N TJ xi SH Φ 4- ⁾ φ d rH 1 4H «. Di to d φ r- { ^• H rβ P 43

^• H d Φ ε n 4H -H Φ 0 d 43 CQ -μ -μ Φ φ N rβ X -H -H £ -μ Xi Φ 4-)

Φ = d • -H 4-) X fβ 3s 4- ⁾ d ~ ^ _ SH = rβ CQ φ TJ X £ SH CJ rH d Φ φ Φ rβ N _. YH-H

N TJ 4H rβ SH Φ 4H Φ TJ d 3Ϊ Φ N Φ rH Φ X -H -μ Φ 43 CQ N 4-) JH Φ Φ

Φ Φ rβ fβ 4H X cn fβ SH d d ε 4-> TJ Di φ 43 d r- Φ Di Φ -H 43 d fβ TJ rH

43 tn TJ • SH JH dd 43 43 d 4H CQ φ dd 43 rH d D) ^■ 5 -H 4H Φ. Φ Φ TJ 43 d 3? X Φ d -H rH rβ d 4 Di Φ d, - _^ SH rβ Φ = 0 Φ Cn rH 43 4 JH ε 4H fβ

SH JH rH N d> Φ 43 Φ 4H 4J rβ ε d d 43 SH ε τι d -H JH <£ P Cn d d

4H Φ 43 d JH -H JH NP d H D> d ^• - '1 *. PQ = rβ 3. 0 ^• H φ Φ rβ dd T Φ Φ d PQ 4H D Φ 4J Φ Φ CQ Φ CQ CQ 43> ε d co d rH φ rβ dd Φ JH -H d CQ> Φ JH 4J Φ co SH 4- ⁾ d -H SH Φ Φ 43 4J Φ 0 SH D)

P rβ -H 43 PQ φ JH rβ -μ CQ Φ -H d Φ -H T Φ T rβ -H CQ 4J TJ d -H Φ d d 43 d Φ JH Φ Φ SH TJ Φ -H

Φ N ε 4-) Φ T 4-) CQ ε fβ X Φ 4J> d

• -rl CJ JH JH 4-) TJ rβ 43 JH 43 d ε -H Xi CQ 4-) Dl TJ d ε d fβ ^

5 φ CQ d Φ CQ T Φ D ⁾ 4 CJ -H d ε Φ CJ m -μ Λ. d Φ dd Φ

N XI rβ d TJ -H Φ ε SH d

TJ Φ d d CQ Φ E CQ JH d d CQ JH D. CQ SH Φ fβ

XI CJ ε 4H X X d d X d Φ rβ TJ -H d JH φ d d -μ = d CQ CQ 0 TJ ≥ rβ 4-) d m TJ d CJ d rβ d rH

-H JH 4- ⁾ ε ε Di Φ d Φ TJ Φ JH D <d Φ 4H Di JH Φ 4H 43 φ d 4H rβ d SH Di 4 dd Φ 5 T Φ 4- ⁾ Φ S d Φ σ. ε dn υ

X! rβ, -3 d φ 4H rH d Φ 4H 4J Φ 4H d -H 43 CQ 4-> d TJ 0 JH CQ JH NT Φ ^• H odd JH JH nd X φ tn d -H CΛ rβ d Φ υ rH JH - μ d H 43 rH Φ φ d Di rH SH rH

JH Φ Λ. Φ Φ rH fβ CJ SH -H rβ ε SH d Φ Φ Φ rH 0 JH φ d PQ 0 43 Φ 43 d xi d ^• H τj 0 P = d X 43 P SH d X Φ 4-1 JH -H -H ^y ω d Φ -μ rβ CQ JH rβ J fβ d υ d TJ d 4H JH rβ Φ W Φ d SH rH DDJN Φ φ> D TJ ε Φ 0 N d N

4H CQ d -H d 43. TJ 4H -H. TJ d 43: fβ CQ CQ -H 43 SH CQ 4-> Φ 43 CQ 43 -H 43 O d -rH Φ 0-. rH d CJ 5 CQ JH rH 5 H SH Φ JH 43 4->-H> JH CQ Φ Φ -H -H d CQ d Φ rH Φ rβ 5 JH rβ>. rβ fβ N d Φ Φ N d Φ SH Φ SH d Φ -H Φ d 43 -H Φ Φ -H d Φ JH in PN PQ TJ N Λ. 3 43 rβ> 43 43 N £ PQ> Φ φ 43 TJ TJ H 0 P 43 N Φ -H to PNP

o in o in O in

H CN CN cn m

- 19 -

By means of comparison and, if necessary, adaptation functions, it is possible to determine system-related speed fluctuations and to compensate for them or to disregard them when calculating the uneven running. This can be, for example, manufacturing tolerances or

Act vibrations or the like. 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 (ntl) - tsk (n) / tsk (n) ³ ).

By assigning the rough running values lut (n) numbered according to the combustions n to the z cylinders 3 of the internal combustion engine 1, for example, cylinder-specific rough running values lut (z, j) are produced per working stroke 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.

If, for example, uneven running values lut (n) and / or lut (z, j) and / or flood (z, j) were determined in block 60 using the described method, 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.

A block 61 checks whether the uneven running value of the - 20 -

cylinder x already switched to homogeneous operation deviates significantly or strongly from the rough running values of the other cylinders. For this purpose, a threshold value for the difference between uneven running values can be specified, the exceeding of which represents a significant deviation.

If the cylinder x which has already been switched over to homogeneous operation has no significant deviation in terms of its uneven running values compared to the other cylinders, the other cylinders are also switched over to homogeneous operation in a block 62. In a subsequent block 63, the throttle valve 12 is set to a stationary value for homogeneous operation and the internal combustion engine 1 continues to be operated in stationary homogeneous operation. The jerk detection is also ended in a block 64.

However, if the rough running values of the cylinder x that has already switched to homogeneous operation deviate significantly from the rough running values of the other cylinders, a difference in torque for each cylinder is determined in a block 65 from the difference in the rough running values, which difference is the difference between shift operation and homogeneous operation for this cylinder indicates.

On the basis of this cylinder-specific torque difference, the torque control is adaptively influenced in a block 66. For example, by changing the retardation of the ignition angle ZW, the torque difference between shift operation and

Homogeneous operation can be minimized or reduced to zero. The same can also be achieved by influencing the supplied fuel mass rk.

After block 66, the internal combustion engine 1 can be returned to the stationary stratified operation. In - 2 1 -

In this case, therefore, it is not completely switched over to homogeneous operation, but rather the cylinder x which has already been switched over to homogeneous operation as the only cylinder is switched back into shift operation. The method is then continued via arrow 67 with block 51, a new limit value R1 limit for filling the combustion chamber 4 being selected in block 53.

Alternatively, the internal combustion engine 1 can also be completely switched over to the homogeneous mode after the block 66. The other cylinders are then also switched over to homogeneous operation. This is indicated by the arrow 68 in FIG. 5.

If changes in the actual torque Md of the internal combustion engine 1 have been detected during the switchover process using the method in FIG. 5, countermeasures are initiated in block 66 as explained. These countermeasures are generally changes in the operating variables of the internal combustion engine 1, with which the actual torque Md of the internal combustion engine 1 is influenced.

When switching from stratified operation to homogeneous operation according to FIGS. 2 and 3, the ignition angle ZW or the ignition timing is retarded in the event of detected torque changes in the area C, so that the excessive filling rl of the combustion chamber 4 and the torque difference detected in this point are compensated and thus the torque changes are reduced. The same applies to a switchover from

Homogeneous operation in the stratified operation in area B of FIG. 4. Such torque changes are dynamic torque changes that can be permanently corrected by adaptive changes to the respective operating variables. 22

In the case of a changeover from homogeneous operation to stratified operation according to FIG. 4, when the torque changes in region C are detected, the fuel mass rk to be injected into the combustion chamber 4 is reduced or increased in such a way that the torque changes detected become smaller. The same applies correspondingly to a changeover from shift operation to homogeneous operation in area B of FIG. 3. Such torque changes are dynamic torque changes which are caused by adaptive changes to the respectively mentioned ones

Farm sizes can be permanently corrected.

The above-mentioned influencing of operating variables of the internal combustion engine 1 to compensate for uneven running or jerking during a switching process can be carried out immediately, so that there may still be an effect during the current switching 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.

Claims

- 23 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 during an intake phase, between the two

Operating modes is switched, and in which the operating variables influencing the actual torque (Md) of 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 of the actual torque (Md) is determined during a switching process (FIG. 5), and that at least one of the operating variables is influenced as a function thereof (66).

2. The method according to claim 1, characterized in that the change in the actual torque (Md) is determined when switching from the first to the second operating mode.

3. The method according to any one of claims 1 or 2, characterized in that the change in the actual torque (Md) is determined in particular in succession at different fillings (rl limit) of the combustion chamber (4).

4. The method according to any one of claims 1 to 3, characterized - 24 -

characterized in that the change in the actual torque (Md) is determined as a function of the detected speed (N) of the internal combustion engine (60).

5. The method according to any one of claims 1 to 4, characterized in that uneven running values are determined for the individual cylinders (60).

6. The method according to claim 5, characterized in that first only one of the cylinders (x) is switched

(58), and that at least one of the rough running values of the switched cylinder (x) is then compared (61) with at least one of the rough running values of at least one of the other cylinders (3).

7. The method according to claim 6, characterized in that the other cylinders (3) depending on the comparison (61) switched (62, 68) or not switched (67).

8. The method according to claim 7, characterized in that a threshold value is predetermined, when it is exceeded, the other cylinders (3) are not switched (67).

9. The method according to any one of claims 6 to 8, characterized in that depending on the comparison

(61) the operating variables of the internal combustion engine (1) are influenced.

10. The method according to any one of the preceding claims, characterized in that the influencing of one of the operating variables is carried out adaptively.

11. The method according to any one of the preceding claims, characterized in that influencing a - 25 -

of the company sizes is only carried out for the next survey process.

12. 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.

13. The method according to any one of the preceding claims, characterized in that in the second operating mode, the ignition angle (ZW) or the ignition timing is influenced in particular in the sense of a retardation.

14. 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 the

Claims 1 to 13 is suitable.

15. Internal combustion engine (1) in particular for one

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 in that a change in the actual torque ( Md) during one

Switching process can be determined by the control unit (16) - 26 -

is (Fig. 5a, Fig. 5b), and that, depending on this, at least one of the operating variables can be influenced by the control device (16) (54, 58).