EP2640947A1

EP2640947A1 - Method and device for controlling a spark ignition engine in the auto-ignition operating mode

Info

Publication number: EP2640947A1
Application number: EP11767730.2A
Authority: EP
Inventors: Axel Loeffler; Wolfgang Fischer; Roland Karrelmeyer; Gerald Graf
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-11-16
Filing date: 2011-10-12
Publication date: 2013-09-25
Also published as: WO2012065788A1; US20130338905A1; CN103201482A; DE102010043966A1; CN103201482B

Abstract

The invention relates to a method for operating a combustion engine in the HCCI mode, having the following steps: a) sensing (S1) of a profile of a measured value of a variable in a combustion chamber of a cylinder (3) of the combustion engine (2); b) acquisition (S2) of one or more combustion features (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of a combustion process in a first combustion cycle based on the measured profile of the measured variable; c) determination (S3), in particular modelling, of a first value of a state variable at a defined time after the first combustion cycle and before a second subsequent combustion cycle based on the acquired one or more combustion features (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%); d) determination (S4) of desired setpoint values of one or more combustion features of a combustion process in the second subsequent combustion cycle; e) determination (S5), in particular modelling, of a second value of the state variable at the defined time on the basis of the setpoint values of the one or more combustion features (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of the second combustion cycle; and f) actuation (S8) of the combustion engine (2) starting from the defined time as a function of the first value of the state variable and the second value of the state variable.

Description

description

title

Method and device for controlling a gasoline engine in auto-ignition operation

Technical area

The invention relates to gasoline engines, in particular to methods for operating gasoline engines with a so-called HCCI process (HCCI: homogeneous from charge compression ignition), a homogeneous autoignition process.

State of the art

According to new operating procedures gasoline engines can be operated in certain operating areas with a so-called HCCI process, which corresponds to a homogeneous auto-ignition process. The HCCI process is a lean burn process which aims to achieve a significant 10-15% reduction in fuel consumption according to the NEDC (NEDC: New European Driving Cycle). This is achieved in operating the gasoline engine according to the HCCI process by throttling the engine operation and by a thermodynamically favorable combustion. In this case, although the downstream 3-way catalyst in lean operation does not nitrogen-reducing, the pollutant raw emissions, especially nitrogen oxides are not significantly increased.

Since the gasoline fuel and the compression ratio of a conventional gasoline engine are designed so that autoignition (which is usually manifested by knocking) are avoided as far as possible, the thermal energy required for the HCCI process must be provided elsewhere. This can be done in different ways. On the one hand can be kept in the combustion chamber by retaining or by sucking back hot, to be discharged in normal operation via exhaust valves residual gas, so there is an increased thermal energy is available. On the other hand, the supplied by the gasoline engine fresh air can be heated in this operating method.

In providing the thermal energy by retaining or sucking back hot internal residual gas, especially in marginal areas of an operating range in which HCCI operation is provided, there is the possibility of spontaneously occurring instability leading to combustion misfires and / or knocking, i. can lead to engine-damaging burns. Furthermore, the HCCI process requires cycle-to-cycle, which otherwise would not occur in nearly full gas change internal combustion engines.

Coupling a special control or regulation. The cycle-to-cycle coupling, i. the influence of the course of a combustion cycle on a subsequent combustion cycle in a cylinder can, in the case of retention of residual gas, also be reflected in the dynamics, e.g. during gas exchange or operating mode switching, causing destabilizing effects.

In order to be able to exclude the instabilities occurring at the edge regions of the HCCI operating range, even in the event of component aging and strongly varying environmental conditions, either the operating range that can be used for HCCI operation would have to be severely restricted or it would have to be otherwise

Measures are taken with regard to the control or regulation. For example, the momentum dynamics could be severely limited, which greatly limits the drivability of the motor vehicle powered by the internal combustion engine.

The cycle-to-cycle coupling in the retention of residual gas leads to a spontaneous change of the combustion positions in successive combustion cycles. This can be manifested, for example, by fluctuations in the peak pressure occurring during combustion.

Essentially two effects are responsible for the changes in the combustion positions. On the one hand, the combustion chamber temperature when opening the exhaust valve at a later combustion at a higher level, resulting in a higher thermal energy of the retained or sucked back residual gas. As a result, the combustion takes place in the following Cycle earlier. Furthermore, incomplete combustion can lead to the transfer of fuel to the next combustion cycle, where it leads to a higher energy conversion during combustion in the usual for HCCI process excess air (lean operation). These effects can lead to a considerable dispersion of the combustion position, which can trigger instabilities, for example with regard to smoothness, in marginal operating ranges of the HCCI method.

It is an object of the present invention to compensate for the effects due to cycle-to-cycle coupling in order to utilize the maximum operating range for HCCI operation.

Disclosure of the invention

This object is achieved by the method for operating a gasoline engine in HCCI operation according to claim 1 and by the device of the engine system according to the independent claims.

Further advantageous embodiments are specified in the dependent claims.

According to a first aspect, a method for operating an internal combustion engine in HCCI mode is provided. The method comprises the following steps:

a) detecting a course of a measured variable of a size in a combustion chamber of a cylinder of the internal combustion engine;

b) determining one or more combustion characteristics of combustion in a first combustion cycle based on the measured history of the measurand;

c) determining a first value of a state variable at a predetermined time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more combustion characteristics;

d) determining desired set points of one or more combustion characteristics of combustion in the second subsequent combustion cycle;

e) determining or modeling a second value of the state variable the set time based on the set values of the one or more combustion features of the second combustion cycle; and f) activating the internal combustion engine from the specified time depending on the first value of the state variable and the second value of the state variable.

One idea of the above method is to calculate a first value of the state variable at a fixed point in time by forward calculation on the basis of one or more combustion characteristics calculated from a curve of a variable of a variable in a combustion chamber of a cylinder of the internal combustion engine and optionally of measured values and / or model values of further state variables eg using thermodynamic relationships to determine. Furthermore, based on desired combustion characteristics of a combustion of a subsequent combustion cycle, a second value of the state variable is determined by recalculation to the specified time based on values of further state variables that depend on ambient conditions. The desired combustion characteristics arise from the desire to run the combustion processes (in steady-state operation) as possible in the same way, e.g. as the same combustion characteristics as in the first combustion cycle so that cycle-to-cycle variations do not occur. Depending on the first value of the state variable and the second value of the state variable, a manipulated variable is corrected. For example, the manipulated variable may indicate the amount of fuel supplied, the injection timing for the injection of fuel and / or the timing of the closing of the intake valve, in order thus to e.g. to increase or decrease the temperature.

By setting the injection timing, it is e.g. possible to compensate for the instability occurring in the edge region of the operating range for HCCI operation. This makes it possible to use the entire operating range for HCCI operation and, furthermore, that no destabilizing effects occur even in dynamic operation.

According to alternative embodiments, the first value of the state variable at the fixed time before or after an injection start of a next injection of fuel into the cylinder based on the determined one or more determined combustion characteristics.

Furthermore, it can be provided that the internal combustion engine is controlled as a function of a deviation between the first value of the state variable and the second value of the state variable.

In particular, the internal combustion engine can be controlled with one or more manipulated variables, the setpoint values of the one or more manipulated variables being iteratively adjusted by executing step e) one or more times depending on a deviation between the first value of the state variable and the respectively determined second value of the state variable can be.

In this case, the one or more manipulated variables may include an injection quantity and / or an injection time.

Furthermore, a cylinder pressure can be determined as the measured variable.

From the course of the cylinder pressure, a heating course of the combustion in the cylinder can be determined, wherein the one or more combustion characteristics are determined from the heating course.

According to one embodiment, the one or more combustion features may correspond to a crankshaft angle location for a given proportion of mass conversion and / or for a given proportion of energy expenditure.

The second value of the state quantity may be further determined at the set time based on an indication of an opening angle of an intake valve and / or a closing angle of an intake valve.

It may be provided that the first value of the state variable at the specified time is further determined based on an indication of an opening angle of an outlet valve and / or a closing angle of the outlet valve. In another aspect, an apparatus for operating an internal combustion engine in HCCI operation is provided, the apparatus being configured to:

to receive a course of a measurand of a variable in a combustion chamber of a cylinder of the internal combustion engine;

to determine one or more combustion characteristics of combustion in a first combustion cycle based on the measured history of the measurand;

to determine a first value of a state variable at a predetermined time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more determined combustion characteristics;

to determine setpoints for one or more combustion characteristics of combustion in the second subsequent combustion cycle;

to determine a second value of the state quantity at the predetermined time based on the set values of the one or more combustion characteristics of the second combustion cycle; and

- To control the internal combustion engine from the specified time depending on the first value of the state variable and the second value of the state variable.

In another aspect, an engine system is provided. The engine system includes:

an internal combustion engine;

a sensor for detecting a history of a quantity of a quantity in a combustion chamber of a cylinder of the internal combustion engine;

a control unit,

to determine one or more combustion characteristics of combustion in a first combustion cycle based on the measured history of the measurand; to determine a first value of a state variable at a predetermined time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more determined combustion characteristics; to determine setpoints for one or more combustion characteristics of combustion in a second subsequent combustion cycle;

to determine a second value of the state quantity at the set time based on the set values of the one or more combustion characteristics of the second combustion cycle; and

in order to control the internal combustion engine from the specified time depending on the first value of the state variable and the second value of the state variable.

According to another aspect, there is provided a computer program product including a program code which, when executed on a data processing unit, executes the above method.

Brief description of the drawings

Preferred embodiments will be explained in more detail with reference to the accompanying drawings. Show it:

Figure 1 is a schematic representation of an engine system with a gasoline engine;

FIGS. 2a to 2c are diagrams illustrating cycle-to-cycle

Variations in operation of the gasoline engine in conventional HCCI operation;

FIGS. 3a to 3c are diagrams for illustrating the time profiles of the

Cylinder pressure, the cylinder temperature and the gas mass components in the combustion chamber in the stationary HCCI operation according to the inventive method;

FIG. 4 is a flow chart illustrating a method of operating the motor system of FIG. 1; and

FIGS. 5a and 5b show a measured cylinder pressure profile and the resulting energy release during two consecutive combustion cycles.

Description of embodiments FIG. 1 schematically shows an engine system 1 with an internal combustion engine 2 which has four cylinders 3 in the present exemplary embodiment. However, the number of cylinders 3 is not limited to four, and basically, any number of cylinders 3 may be provided.

The internal combustion engine 2 is embodied as a gasoline engine and has injection valves 5 on each of the cylinders 3 for a direct injection of fuel. Fresh air is supplied to the cylinders 3 of the internal combustion engine 2 via an air supply section 9 and is admitted into the cylinders 3 controlled by respective intake valves 6. For this purpose, the fresh air is sucked in with an ambient air pressure po and with an ambient air temperature T ₀ from an environment of the engine system 1 and passed through an air filter 10 into a Saugrohrab- section 12. The Saugrohrabschnitt 12 is located downstream of the air filter 10 between a throttle valve 1 1 and the intake valves 6 of the internal combustion engine 2. In the air supply section 9 upstream of the throttle valve 1 1, an air mass sensor 16 is provided to detect the amount of air flowing in Saugrohrabschnitt 12.

Combustion exhaust gas resulting from combustion in the cylinders 3 is exhausted via exhaust valves 7 into an exhaust discharge portion 8. In the Saugrohrabschnitt 12 opens an exhaust gas recirculation line 13, which connects the Abgasabführungsabschnitt 8 with the Saugrohrabschnitt 12. In the exhaust gas recirculation line 13 is an exhaust gas cooler 14 and an exhaust gas recirculation valve

15 is provided to adjust the amount and temperature of the recirculated exhaust gas can. The state variables in the suction pipe section 12 are the intake manifold pressure p ₂ and the mass flow m ₂ of the air-exhaust gas mixture to be supplied to the cylinders 3. In the exhaust gas removal section 8, an exhaust gas pressure p ₃ and an exhaust gas mass flow m _{3 are established} .

The internal combustion engine 2 is operated by means of a control unit 20. The control unit 20 controls to operate the internal combustion engine 2 position sensor of the engine system 1, such. the throttle valve 1 1 for adjusting the amount of air supplied to the cylinders, the exhaust gas recirculation valve 15 for adjusting a

Exhaust gas recirculation rate, which indicates the amount of inert gas in the cylinders, the Inlet and exhaust valves 6, 7 and the injectors 5 for adjusting the timing and duration of the fuel injection. The operation of the internal combustion engine 2 is based on state variables that can be measured and / or at least partially modeled. State variables are, for example, the intake manifold pressure p ₂ , the air mass flow m ₀ flowing into the intake pipe section 12, which is detected by the air mass sensor 16, the exhaust back pressure p ₃ , the rotational speed of the internal combustion engine 2 and the torque of the internal combustion engine 2.

Furthermore, the cylinders 2 are provided with a cylinder pressure sensor 17 in order to detect a current cylinder pressure and to provide a corresponding indication to the control unit 20.

The control unit 20 operates the internal combustion engine 2 in the present embodiment so that in a certain operating range can be specified by the speed and / or torque and / or the intake manifold pressure p ₂ , the internal combustion engine 2 in a HCCI operation, ie in a Auto-ignition operation is operated. When HCCI operation, which is taken in particular at a partial load of the internal combustion engine 2, the internal combustion engine 2 is operated so that combustion takes place in an excess of air, wherein the air-fuel mixture ignited in the combustion chamber itself.

For this purpose, it is provided that the internal combustion engine 2 is operated so that the combustion chamber temperature during the combustion chamber compression (compression movement of the piston) is increased so that the ignition temperature of the air-fuel mixture is exceeded and a self-ignition occurs. In particular, at peripheral areas of the operating range in which HCCI operation is to take place, fluctuations may occur due to a feedback effect. The feedback effect arises from the fact that a large amount of hot residual gas from the previous combustion is retained. If this has a very different temperature level, strongly different combustion conditions occur in the following cycle. If this retained residual gas still contains unburned fuel components, the result is a higher energy conversion in the combustion chamber due to an excess of air in the combustion chamber. This effect is shown for example in the diagram of FIG. 2a. There it can be seen that the respective maximum pressure p _cy i fluctuates from cycle to cycle during a combustion cycle. These cycle-to-cycle variations lead to instabilities that can be felt by knocking or combustion misfires in the combustion chambers. In order to use the maximum operating range for HCCI operation, this cycle-to-cycle fault must be compensated so that the maximum pressure p _cy i of the burns (steady state engine operation) is approximately constant for successive combustion cycles. This can be achieved by implementing a control method based on a customized thermodynamic model of the combustion chamber.

In FIG. 2b the feature NMEP is plotted against the crankshaft angle. The characteristic NMEP (Net Mean Effective Pressure) is a measure of the average induced work.

In FIG. 2c, the characteristic MFB50% is plotted against the crankshaft angle MFB50% corresponds to a combustion center position which is indicated as crankshaft angle difference to the crankshaft angle of the upper tonal point.

The cycle-to-cycle coupling of the combustion cycles is mainly due to the fact that in HCCI operation there is no complete gas exchange in the combustion chamber so that residual gas remaining in the combustion chamber or being sucked back will affect subsequent combustion in HCCI operation due to its variable temperature.

The basic differential equation for cylinder pressure is as follows: dp ( _K _ ₁ ). f ^ ₊ ^a q ^ ₊ gggii; 1 _K j |

dtp 7 (φ} K άφ dtp dtp J ^' άφΐ (1) where p indicates the cylinder or combustion chamber pressure, φ the crankshaft angle, V the instantaneous cylinder volume dependent on the crankshaft angle φ, which results kinematically from the geometry of the crank operation, κ den instantaneous polytropic exponent derived from the gas composition at dependent on the instantaneous temperature, ie the enthalpy flows associated with the mass flows through the valves (in the inlet and outlet operations) and the energy release during combustion also called combustion history, and dQ _DW indicate the wall heat losses. dQ _Bre nn is also called the burning process

The above differential equation can be derived from the law of conservation of energy and the ideal gas law. This takes place taking into account the conditions in the container models, namely the pressure p, the temperature T and the gas mass components of the substances involved. Approximately the

Gas mass components summarized. The conversion of the gas mass components air, residual gas and fuel is coupled to the phenomenologically modeled energy release rate in the stoichiometric ratio. Furthermore, the instantaneous combustion chamber temperature is determined as a derived quantity via the ideal gas law after determining the pressure profile.

Forming the above equation 1, we obtain a formula for the so-called heating process, which corresponds to the combustion process minus the wall heat loss, and can be calculated on the basis of a measured cylinder pressure curve.

^ QBeizveriamf ^ QBrsnn, d QDW, d-H ϊ,. dp, κ dV

= 1 ^: 1 =; Ff φ) 1 ρ- (2) άφ Λφ ύφ ύψ (κ-ί) dtp κ-1 άφ

It can be assumed that during the combustion process no gas mass flows through the intake and exhaust valves occur (dH = 0) and one can consider κ as constant or at least as linearly dependent on the crankshaft angle φ. To improve the accuracy, κ can be selected depending on the operating point. Integrating Equation 2, it is possible to extract from the resulting integral heating curve Q (cp) certain features characterizing the combustion. In particular, the crankshaft angle φ, at which the combustion begins or at which a certain proportion (x%) of the total energy conversion has taken place during the combustion cycle (mass conversion point), is of interest for the control to be implemented. This crankshaft angle becomes SOC

(start of combustion) or MFBx% called (mean fraction burnt), where MFB10% 10% mass conversion, MFB50% indicate the center of gravity of combustion during the combustion cycle and MFB90% 90% mass conversion. Furthermore, in the control, the energy values belonging to the crankshaft angle Qx% = Q (MFBx%) can be used.

_{FIGS. 3 a to 3 b show} the time profiles of the cylinder pressure p _cy i, the cylinder _temperature T _cy i and the gas mass _components m _cy i. In particular, the time profiles of the cylinder _temperature T _cy i and the gas mass _components m _cy i are based on currently available measurement only very limited or not accessible via measurements.

In the following, however, this information or the difference between the actual values of these quantities will be based on a measurement in a first ((k-1) -th) cycle and the desired setpoints in a subsequent second (k-th) cycle for the Calculation of appropriate control intervention used. The

Method for determining the control of the internal combustion engine will be described in more detail with reference to the flowchart of Figure 4.

In a first step S1, a profile of a cylinder pressure is detected with the aid of the cylinder pressure sensor 17 in a combustion chamber of one or more cylinders 3 of the internal combustion engine 2. From the course of the cylinder pressure are in

Step S2 determines one or more combustion characteristics of a combustion in a first combustion cycle that has just taken place based on the measured cylinder pressure curve. As described above, in step S3, a first value of a state quantity at a predetermined time after the first combustion cycle z. B. before an injection start of a next injection of fuel into the cylinder based on the determined one or more determined combustion characteristics (eg SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) determined or to be modeled. This has the advantage that the injection quantity for an immediately following combustion can be adjusted in accordance with the result of the method.

Alternatively, in step S3, the first value of the state quantity at the predetermined time after injection start of next injection of fuel into the cylinder based on the determined one or more combustion characteristics (eg SOC, MFB10%, M FB50%, M FB90 % Q10%, Q50%, Q90%) can be determined or modeled. For example, the times of opening or closing of the respective intake valve may be provided as suitable times for determining the first value of the state variable.

Further, in step S4, setpoint values for one or more combustion characteristics of combustion are determined in a second combustion cycle following the first. From this, in step S5, a second value of the state quantity is determined or modeled at the predetermined time based on the one or more combustion characteristics of the second combustion cycle. In step S6, at least one correction value for at least one manipulated variable for driving the internal combustion engine 2, e.g. an injection amount or an injection timing, determined. If it is determined in step S7 that a measure of a deviation between the first and the second value falls below a certain predetermined threshold value (alternative: yes), then the internal combustion engine 2 is actuated in step S8 starting from the specified point in time with the at least one corrected manipulated variable. Otherwise (alternative: No), the program jumps back to step S4 in order to carry out the modeling and the determination of the second value of the state variable again based on the at least one corrected manipulated variable until the measure of the deviation between the values of the state variables falls below the predefined threshold value.

To increase the robustness of the thermodynamic model, the state in the cylinder is estimated at the beginning of the combustion cycle and the model is initialized with the estimated value for the subsequent calculation.

The estimation of the cylinder state at the start of combustion is based on the known auto-ignition temperature TZÜND of Otto fuel of about 1000 ° K, as well as on the determined from the combustion chamber pressure signal timing of the start of combustion SOC. Together with the measured cylinder pressure at start of combustion p (SOC), the gas constant R determined from a given mixture composition and the cylinder volume V (SOC) calculated depending on the start of combustion, the gas mass in the cylinder 3 and thus the cylinder state can be estimated with the help of the ideal gas law. pV

• V = mRT or m = -

KT

The start of combustion SOC can in this method from the measured combustion chamber pressure curve, e.g. be determined by means of a known from the prior art Heizverlaufsrechnung. For the reliable determination of the start of combustion, an increased polytropic exponent of κ = 1.4 is used for the heating process calculation.

To increase the accuracy of the estimation method, an iterative method can be used e.g. A Newton iteration method may be used in which the gas constant R is dependent on the estimated cylinder state at the start of combustion in the cylinder 3, i. is corrected depending on the mixture composition of air, fuel and residual gas resulting from the estimated cylinder mass. In particular, this is done by the gas constants of the individual substances, according to their volume fraction of the resulting air-fuel

Mixture in cylinder 3 are weighted.

In the figures 5a and 5b, a measured cylinder pressure curve and is derived according to equation 2 heating course dQ _He izveriauf resulting energy are giefreisetzung shown in two consecutive combustion cycles.

The first combustion cycle is assumed to be given in this example, with the states representing the actual state during the first combustion cycle. The subsequent second combustion cycle is intended to represent a desired energy release Q.

The desired energy release is characterized by one or more of the above features, eg SOC, MFB10%, MFB50% and MFB90% as well as Q10%, Q50% and Q90%, respectively. Based on the available actual combustion characteristics, the values of the control variables known from the control, such as the opening and closing angle of the exhaust valves and the estimated states in the cylinder at the start of combustion in the first combustion cycle, the states can until the beginning of an intermediate compression whose time corresponds to a predetermined crankshaft angle before the start of combustion and which is represented by the dashed line can be calculated. Conversely, based on the available setpoint combustion characteristics, the target cylinder state derived therefrom at the start of combustion of the second cycle, the values of the manipulated variables known from the control, such as opening time and closing time of the intake valve, can be used to calculate the states back to the beginning of the intermediate compression , From the difference of the state variables resulting from the forward calculation starting from the first cycle and the backward calculation, starting from the second cycle, a correction of the manipulated variables, namely the time of the injection and the injection quantity can then be made.

This correction of the control variables can be carried out as a function of a difference between the first and second values of the state variable, for example with the aid of a predetermined function or a predetermined characteristic diagram.

The adaptation / correction of the state variables can, for example, also be carried out iteratively, wherein an incremental correction of the injection time and / or the injection quantity is performed and a corresponding re-calculation back from the desired state is made again until the calculation from the forward calculation starting from the first combustion cycle and by the backward calculation, starting from the second combustion cycle, the difference of the state variables falls below a predetermined tolerance deviation. Alternatively or additionally, combustion characteristics derived from the state variables, e.g. the thermal energy at the beginning of the intermediate compression (or at some other predetermined reference time), as input for the calculation of the injection corrections, i. the adaptation of the injection timing and the injection quantity are used.

While the above method has been explained on the basis of steady-state engine operation, it can also be applied to dynamic operation with the difference that the setpoint values for the combustion characteristics and the pre-control values for the manipulated variables also change in the dynamics from cycle to cycle must be considered accordingly.

Claims

Method for operating an internal combustion engine (2) in HCCI mode, comprising the following steps:

a) detecting (S1) a course of a measured variable of a size in a combustion chamber of a cylinder (3) of the internal combustion engine (2);

b) determining (S2) one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of combustion in a first combustion cycle based on the measured history of the measurand;

c) determining (S3), in particular modeling, a first value of a state variable at a fixed time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%). , Q10%, Q50%, Q90%);

d) determining (S4) desired desired values of one or more combustion characteristics of combustion in the second subsequent combustion cycle;

e) determining (S5), in particular modeling, a second value of the state quantity at the fixed point in time based on the desired values of the one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) the second combustion cycle; and

f) driving (S8) of the internal combustion engine (2) from the specified time depending on the first value of the state variable and the second value of the state variable.

2. The method of claim 1, wherein the first value of the state quantity at the predetermined time before or after an injection start of a next injection of fuel into the cylinder based on the determined one or more determined combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%).

The method of claim 1 or 2, wherein the internal combustion engine (2) is driven depending on a deviation between the first value of the state variable and the second value of the state variable.

Method according to one of claims 1 to 3, wherein the internal combustion engine (2) is controlled with one or more manipulated variables, wherein the one or more manipulated variables iteratively by one or more times performing step e) depending on a deviation between the first value of the state variable and the respectively determined second value of the state variable.

The method of claim 4, wherein the one or more manipulated variables include an injection amount and / or an injection timing.

Method according to one of claims 1 to 5, wherein a cylinder pressure (pcyi) is determined as the measured variable.

The method of claim 6, wherein a course of combustion in the cylinder (3) is determined from the course of the cylinder pressure, wherein the one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90 %) from the heating process.

The method of claim 6, wherein the one or more combustion features (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of a crank angle position at the start of combustion and / or at a predetermined proportion of mass conversion and / or at corresponds to a predetermined proportion of an energy conversion.

Method according to one of claims 1 to 8, wherein the second value of the state quantity at the predetermined time further based on an indication of an opening angle of an exhaust valve (7) and / or a closing angle of an exhaust valve (7) is determined.

0. The method of claim 1, wherein the first value of the state quantity at the set time is further determined based on an indication of an opening angle of an exhaust valve and / or a closing angle of the exhaust valve.

An apparatus for operating an internal combustion engine (2) in HCCI operation, the apparatus being configured to:

to receive a course of a measured quantity of a variable in a combustion chamber of a cylinder (3) of the internal combustion engine (2);

to determine one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of combustion in a first combustion cycle based on the measured history of the measurand;

a first value of a state variable at a specified time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90 %) to investigate;

- to setpoint values of one or more combustion characteristics (SOC,

MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of combustion in a second subsequent combustion cycle;

to determine a second value of the state quantity at the set time based on the set values of the one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of the second combustion cycle; and

- To the internal combustion engine (2) from the specified time depending on the first value of the state variable and the second value of the state variable to control. 12. engine system (1) comprising:

an internal combustion engine (2);

a sensor (17) for detecting a history of a measurand of a quantity in a combustion chamber of a cylinder of the internal combustion engine (2); a control unit (20),

- one or more combustion characteristics (SOC, MFB10%,

MFB50%, MFB90%, Q10%, Q50%, Q90%) of a combustion in determine a first combustion cycle based on the measured course of the measured variable;

a first value of a state variable at a predetermined time after the first combustion cycle and before a second subsequent combustion cycle based on the determined one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%). ) to investigate;

to determine setpoints of one or more combustion characteristics (SOC, MFB10%, MFB50%, MFB90%, Q10%, Q50%, Q90%) of combustion in the second subsequent combustion cycle;

in order to control the internal combustion engine (2) from the fixed point in time depending on the first value of the state variable and the second value of the state variable.

A computer program product containing program code which, when executed on a data processing unit, executes the method of any one of claims 1 to 10.