SE1350508A1 - Method and system for controlling an internal combustion engine through control of combustion in an internal combustion chamber during the current combustion cycle - Google Patents

Abstract

The present invention relates to a method of controlling an internal combustion engine (101), said combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said combustion chamber (201), wherein combustion in said combustion chamber. combustion chamber (201) occurs in combustion cycles. The method Or characterized by: during a first combustion cycle, determining at least one first parameter value for a quantity in combustion in said combustion chamber (201), based on said first parameter value, estimating a representation of a during said first combustion cycle and In said combustion chamber (201) resulting pressure amplitude, and based on said estimated pressure amplitude regulate subsequent combustion. The invention also relates to a system and a vehicle. Fig. 3

Description

BACKGROUND OF THE INVENTION The present invention relates to internal combustion engines, and more particularly to a method of controlling an internal combustion engine according to the preamble of claim 1.

The invention also relates to a system and a vehicle, as well as a computer program and a computer program product, which implement the method according to the invention.

Background of the Invention The following description of the invention constitutes a background description of the invention, and thus does not necessarily constitute prior art.

Concerning vehicles in general and at least in some heavy vehicles in particular, there is a constant development in pursuit of fuel efficiency and reduced exhaust emissions. Due to e.g. Increased government interests regarding pollution and air quality in e.g. In urban areas, emission standards and regulations have been developed in many jurisdictions. When driving heavy vehicles, such as trucks, buses and the like. Over time, the vehicle economy has also had an increasing impact on the profitability of the business in which the vehicle is used. In addition to the vehicle's acquisition cost, the main expense items for current operation of wages for the vehicle's driver, costs for repairs and maintenance as well as industry for propulsion of the vehicle. Thus, it is important for each of these areas to try to reduce the cost in the best possible way.

In addition to economic / environmental aspects as above, there are also additional aspects that should be taken into account when designing vehicles. For example. Driver comfort is important, perhaps especially for heavy vehicles, and starting work is also often put on 2 million passengers. This includes work with sound comfort, ie. minimization / optimization of, above all, unwanted noise / noise to which the driver is exposed when driving the vehicle, where loud or otherwise disturbing noises can have a negative effect on the driver's driving of the vehicle, e.g. by causing stress and / or fatigue.

Another aspect is the sound the vehicle emits to its surroundings, ie. how the vehicle's progress is audibly experienced in the environment in which the vehicle is driven. For example. In this regard, there may also be laws and regulations that regulate permitted sound emissions from vehicles.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of controlling an internal combustion engine. This object is achieved by a method according to claim 1.

The present invention relates to a method of controlling an internal combustion engine, said combustion engine comprising at least one combustion chamber and means for supplying fuel to said combustion chamber, wherein combustion in said combustion chamber takes place in combustion cycles. The method is characterized in that: during a first combustion cycle, determining at least one first parameter value for a quantity in combustion in said combustion chamber, based on said first combustion value, pressure amplitude, and 3 - based on said estimated pressure amplitude, regulate subsequent combustion.

As mentioned above, the sounds generated when driving a vehicle, and which are often considered to a large extent as unwanted noise, are an important parameter not only in the effort to achieve a good driving environment, but also from the environment in which the vehicle is driven. .

In vehicles, as is the case, many noises / noises are made, and a main source is the internal combustion engine.

The sound produced by an internal combustion engine depends to a large extent on the combustion in the combustion chamber of the internal combustion engine, and above all on the manner in which the pressure changes during combustion. The resulting sound will at least partly depend on the maximum pressure amplitude, ie. the maximum pressure that arises during combustion. Noise is also caused by pressure changes, and cid especially when the pressure rises rapidly.

According to the present invention, the combustion is regulated with respect to the pressure level which arises during the combustion, such as e.g. by means of a control which aims to limit the maximum pressure that can arise during a combustion (combustion cycle).

According to one embodiment, the manner in which the pressure changes during combustion is also regulated, in particular during an ongoing pressure increase, and in particular a regulation which aims to limit the maximum pressure change rate which arises during combustion.

The control of the combustion can be arranged to be performed individually for each cylinder, and the combustion can be regulated for a subsequent combustion cycle based on information from one or more previous combustion cycles. According to one embodiment, a representation is estimated the maximum pressure amplitude that is expected to result during a combustion cycle, whereby the combustion of a subsequent combustion cycle is regulated based on this estimation, and whereby the regulation at subsequent combustion cycle can be adjusted to avoid e.g. an undesirably high pressure amplitude.

According to one embodiment, an ongoing combustion is regulated during a combustion cycle, the invention providing a control of an ongoing combustion process where control can be performed during ongoing combustion in order to e.g. prevent an unwanted hbg pressure amplitude from arising.

The control according to the present invention can be achieved by establishing during a first part of a combustion cycle a parameter value regarding a quantity in the combustion, such as e.g. a pressure radiating in the combustion chamber. Based on this parameter value, as suedes e.g. radiating pressure, a expected maximum pressure (maximum pressure amplitude) can then be estimated, whereby the combustion during a subsequent part of the combustion cycle can be regulated with respect to the expected maximum pressure amplitude. According to one embodiment, an expected maximum pressure increase rate is also estimated, whereby regulation can also take place with respect to this.

The combustion can e.g. is regulated by determining an injection strategy for application in a subsequent injection during the combustion cycle, whereby in determining the injection strategy a expected maximum pressure amplitude can be estimated, whereby an injection strategy, such as e.g. an injection strategy of a plurality of injection strategies, can be selected, since an injection strategy is chosen which is not expected to result in a reduced pressure development during the combustion. For example. an injection strategy can be chosen which is expected to result in a maximum pressure amplitude which is less than the applicable maximum value for the maximum pressure, where this maximum value amounts to some applicable maximum pressure such as e.g. farvantas result in a emitted sound level which in turn is below any applicable sound level, or meets another criterion regarding emitted sound.

The method of the present invention can e.g. implemented using one or more FPGA (Field-Programmable Gate Array) circuits, and / or one or more ASIC (application-specific integrated circuit) circuits, or other types of circuits that can handle the desired computational speed.

Additional features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments and the accompanying drawings.

Brief Description of the Drawings Fig. 1A schematically shows a vehicle in which the present invention can be used.

Fig. 1B shows a control unit in the control system of the vehicle shown in Fig. 1A.

Fig. 2 shows the internal combustion engine of the vehicle shown in Fig. 1A in more detail.

Fig. 3 shows an exemplary method according to the present invention.

Fig. 4 shows an example of an estimated pressure pair for a combustion, as well as an actual pressure pair up to a first crank angle position. Figs. 5A-B show an example of control in situations with more than three injections.

Fig. 6 shows an example of an MPC control.

Detailed Description of Embodiments Fig. 1A schematically shows a driveline in a vehicle 100 according to an embodiment of the present invention. The driveline comprises an internal combustion engine 101, which in a conventional manner, via a shaft extending on the internal combustion engine 101, usually via a flywheel 102, is connected to a gearbox 103 via a clutch 106.

The internal combustion engine 101 is controlled by the vehicle's control system via a control unit 115. Likewise, the clutch 106, which e.g. can be constituted by an automatically controlled clutch, and the gearbox 103 of the vehicle's control system by means of one or more applicable control units (not shown). Of course, the vehicle's driveline can also be of another type such as e.g. of a type with conventional automatic gearbox or of a type with a manually geared gearbox etc.

A shaft 107 emanating from the gearbox 103 drives drive wheels 113, 114 in the usual manner via end shaft and drive shafts 104, 105. In Fig. 1A only one shaft with drive wheels 113, 114 is shown, but in the usual way the vehicle can comprise more than one shaft provided with drive wheels, as well as one or more additional axles, such as one or more stand axles. The vehicle 100 further comprises an exhaust system with a post-treatment system 200 for the usual treatment (purification) of exhaust emissions resulting from combustion in the combustion chamber of the internal combustion engine 101 (eg cylinders).

Furthermore, internal combustion engines in vehicles of the type shown in Fig. 1A are often provided with controllable injectors for supplying the desired amount of fuel at the desired time in the combustion cycle, as at a specific piston position (crank angle) in the case of a piston engine, to the combustion engine burner.

Fig. 2 schematically shows an example of a fuel injection system for the internal combustion engine 101 exemplified in Fig. 1A. The fuel injection system consists of a so-called Common Rail systems, but the invention is equally applicable to other types of injection systems. Fig. 2 shows only a cylinder / combustion chamber 201 with a piston 203 acting in the cylinder, but the internal combustion engine 101 in the present example consists of a six-cylinder internal combustion engine, and can generally consist of an engine with any number of cylinders / combustion chamber, such as e.g. . any number of cylinders / combustion chambers in the range 1-20 or more. The combustion engine further comprises at least one respective injector 202 for each combustion chamber (cylinder) 201. Each respective injector is used suedes for injection (supply) of fuel into a respective combustion chamber 201. Alternatively, two or more injectors per combustion chamber may be used. The injectors 202 are individually controlled by respective actuators (not shown) arranged at the respective injector, which are based on received control signals, such as e.g. from the control unit 115, controls the opening / closing of the injectors 202.

The control signals for controlling the opening / closing of the injectors 202 by the actuators can be generated by any applicable control unit, as in this example by the motor control unit 115. The motor control unit 115 thus determines the amount of fuel to be actually injected at any given time, e.g. based on the radiating operating conditions of the vehicle 100. 8 The injection system shown in Fig. 2 thus consists of a so-called Common Rail system, which meant that all injectors (and thus combustion chambers) are supplied with fuel from a common fuel line 204 (Common Rail), which with the help of a fuel pump 205 is filled with fuel from a fuel tank (not shown) at the same time as the fuel in the rudder 204, also with the aid of the fuel pump 205, is pressurized to a certain pressure. The highly pressurized fuel in the common rudder 204 is then injected into the combustion chamber 201 of the internal combustion engine 101 upon opening of the respective injector 202. Several openings / rods of a specific injector can be made during one and the same combustion cycle, thus several injections can be made during a combustion cycle. Furthermore, each combustion chamber is provided with a respective pressure sensor 206 for emitting signals of a pressure radiating in the combustion chamber to e.g. the control unit 115. The pressure sensor can e.g. be piezo-based and should be so fast that it can emit crank angle-resolved pressure signals, such as e.g. at every 10, every 5 or every crank angle or other applicable range, such as e.g. an oftare.

With the aid of systems of the type shown in Fig. 2, the combustion during a combustion cycle in a combustion chamber can be controlled to a large extent, e.g. by utilizing multiple injections, where injection times and / or duration for each injection can be regulated, and where data from e.g. the pressure sensors 206 can be taken into account in the control.

According to an embodiment of the present invention, the combustion of a subsequent combustion cycle is regulated based on a four-going combustion cycle, i.e. the calculation from a previous combustion cycle is used in regulating a subsequent combustion cycle. According to an embodiment of the invention, e.g. injection times and / or duration of the respective injection and / or injected industry volume during an ongoing combustion cycle based on data from the current combustion cycle.

As mentioned above, the noise which the operation of an internal combustion engine generally gives rise to depends to a large extent on the combustion in the internal combustion chamber of the internal combustion engine, and in particular on the mode in which the pressure changes during combustion. According to the invention, the combustion is regulated primarily with respect to the maximum pressure that is expected to arise in the combustion chamber during the combustion. According to one embodiment, the maximum pressure derivative is also regulated during combustion, ie. the maximum speed at which the pressure changes, and di especially at pressure boiling.

Fig. 3 shows an exemplary method 300 according to the present invention, in which the method according to the present example Or is arranged to be performed by the motor control unit 115 shown in Figs. 1A-B.

General control systems in modern vehicles consist of a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECUs) such as the control unit, or controller, 115, and various components arranged in the vehicle.

As OrkOnt, such control systems may comprise a starting number of control units, and the responsibility for a specific function may be divided into more than one control unit.

For the sake of simplicity, shown in Figs. 1A-B, only the motor control unit 115 in which the present invention Or is implemented in the embodiment shown. However, the invention can also be implemented in a control unit dedicated to the present invention, or in whole or in part in one or more other control units already existing in the vehicle. In view of the speed at which calculations according to the present invention are carried out, the invention can be arranged to be implemented in a control unit which is specially adapted for real-time calculations of the type as below. Implementation of the present invention has shown that e.g. ASIC and FPGA readings are attenuated and selections are capable of calculations according to the present invention.

The function of the control unit 115 (or the control unit (s) in which the present invention is implemented) according to the present invention may, in addition to being dependent on sensor signals from the pressure sensor 202, e.g. depend on signals from other controllers or sensors. In general, control units of the type shown are normally arranged to receive sensor signals from different parts of the vehicle, as well as from different control units arranged on the vehicle.

The control is often controlled by programmed instructions. These programmed instructions typically consist of a computer program, which when executed in a computer or controller causes the computer / controller to perform the desired control, such as the process steps of the present invention.

The computer program usually forms part of a computer program product, where the computer program product comprises an applicable storage medium 121 (see Fig. 1B) with the computer program stored on said storage medium 121. Said digital storage medium 121 may e.g. consists of ndgon from the group: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc., and be arranged in or in connection with the control unit, the computer program being executed by the control unit. By following the instructions of the other computer program, the behavior of the vehicle in a specific situation can thus be adapted.

An exemplary control unit (control unit 115) is shown schematically in Fig. 1B, wherein the control unit may in turn comprise a bending unit 120, which may be constituted by e.g. any ldmplig type of processor or microcomputer, e.g. a Digital Signal Processor (DSP), one or more Field-Programmable Gate Array (FPGAs) circuits or one or more circuits with an Application Specific Integrated Circuit (ASIC) function.

The calculating unit 120 is connected to a memory unit 121, which provides the calculating unit 120 e.g. the stored program code and / or the stored data calculation unit 120 need to be able to perform calculations. The coverage unit 120 is also arranged to store partial or final results of coverage in the memory unit 121.

Furthermore, the control unit is provided with devices 122, 123, 124, 125 for receiving and transmitting input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes, which of the input signals receiving devices 122, 125 may be detected as information for processing the calculating unit 120. The output signals 123, 124 for transmitting output signals are arranged to convert calculating results from the calculating unit. 120 to output signals for transmission to other parts of the vehicle control system and / or the component (s) for which the signals are intended. Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be formed by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Oriented Systems 12 Transport), or any other bus configuration; or by a tradlbs connection.

Returning to the process 300 shown in Fig. 3, the process starts in step 301, where it is determined whether the inventive control of the combustion process is to be performed. The regulation according to the invention can e.g. yara arranged to be carried out continuously as soon as the internal combustion engine 101 is started. Alternatively, the regulation can be arranged to be performed e.g. as long as the combustion engine combustion is not to be regulated according to any other criterion. For example. there may be situations where it is uncommon for regulation to be carried out based on factors other than the noise made in the first place. According to one embodiment, control of the combustion is performed simultaneously with reference to emitted sound during combustion and at least one additional control parameter. For example. a deviation can be made, where the priority of the control parameters is met in the desired control result, e.g. yara can be arranged to be controlled according to any applicable cost function.

The method according to the present invention thus consists of a method for controlling the internal combustion engine 101 while combustion takes place in said combustion chamber 201 in combustion cycles. As Or edge, the term combustion cycle is defined as the steps a combustion yid an internal combustion engine includes, such as e.g. the two-stroke engine's two-stroke engine and the four-stroke engine's four-stroke engine, respectively. The term includes Oven cycles where no fuel is actually injected, but where the internal combustion engine arida driys yid somewhat varytal, as of the vehicle's drive wheels via the driylinan yid e.g. relaxation. Dys. In addition to no injection of fuel, a combustion cycle still takes place for e.g. yarje two vary (for four-stroke engine), or e.g. yarje vary (two-stroke engine), which rotates the output shaft 13 of the internal combustion engine. The same applies to other types of internal combustion engines.

In step 302 it is determined whether a combustion cycle has or will be started, and when so, the procedure proceeds to step 303 at the same time as a parameter in the representative injection number is set equal to one.

In step 303, an injection scheme / control alternative is established which is expected to result in an undesired pressure development during the combustion cycle, such as e.g. an injection scheme that is expected to limit the maximum pressure amplitude in the combustion chamber during the combustion cycle combustion.

In general, the supply of the multitude of industries both in terms of quantity and in what way, ie. the one or more fuel injections to be performed during the combustion cycle are normally predefined, e.g. depending on the work (torque) that the internal combustion engine is to perform during the combustion cycle, since modification of the established injection schedule is not performed during an ongoing combustion cycle according to prior art. Predefined injection schedules can e.g. are tabulated in the vehicle's control system for a starting number of operating cases, such as different engine speeds, different work required, different combustion air pressures, etc., where tabulated data e.g. may have been produced by appropriate tests / feeds at e.g. development of an internal combustion engine and / or vehicle, whereby the applicable injection schedule / control alternative can be selected based on prevailing conditions, and where the injection schedule can be selected or be pre-adapted to e.g. result in a predicted maximum pressure amplitude that is slightly below the applicable pressure gauge value. 14 These injection schedules / control alternatives can consist of the number and properties of the injections in the form of e.g. time (crank angle law) for start of injection, length of injection, injection pressure, etc., and thus are stored for a start number of operating cases in the vehicle's control system, and e.g. be protruded / fed with the grind to result in a maximum pressure amplitude that is less than the applicable pressure. The injections may also be developed for the purpose of fulfilling the other milestones, such as delivering the desired work, resulting in a certain maximum heat loss, a certain exhaust temperature, etc., whereby the injections may be produced based on a weighting of several parameters.

According to the present embodiment, therefore, in step 303, such a predetermined injection schedule is applied, where this predetermined injection schedule is thus selected, e.g. by table look-up, based on prevailing conditions and desired work done by the internal combustion engine, where the desired (requested) done work is normally controlled (beg-Ors) by some superior / other process, such as e.g. based on a request for propulsion from the vehicle driver and / or a cruise control system.

According to one embodiment, an injection schedule is established which results in at least half of the desired work being exhausted to ensure that the exhausted work cannot be regulated to too log level.

According to one embodiment, the injection schedule is determined entirely according to e.g. the calculations shown below, where e.g. different pre-defined injection schedules can be compared with each other to determine a most preferred injection schedule, but in the calculation example exemplified below, the calculations are applied only after injection has been started during the combustion cycle. Since specific assumed ratios are likely to result in the same hazardous injection schedule each time, it may be advantageous to select an injection schedule for a combustion cycle by any type of lookup and clamed to reduce the calculation load, calculating as follows only after injection has been papered. In addition to the following examples of how the injection schedule can be determined, other models with a corresponding function can alternatively be applied.

Thus, according to the present embodiment, in step 303, a predetermined injection schedule is established at the beginning of the combustion cycle, wherein control according to the invention is performed only after fuel injection has been started during the combustion cycle, as only after at least one injection has been performed during the combustion cycle, or after has been paborjats.

Thus, fuel injection is normally performed according to a predetermined schedule, where a plurality of injections may be arranged to be performed during one and the same combustion cycle. This means that the injections can be relatively short. For example. There are injection systems with 5-10 fuel injections / combustion, but the number of fuel injections can also be significantly larger than said, such as e.g. on the order of 100 fuel injections during a combustion cycle. The number of possible injections is generally controlled by the speed at which the organs with which the injection is performed have, ie. in the case of Common Rail systems of how quickly the injectors can be opened shut down. According to the present example, at least two fuel injections are carried out during one and the same combustion cycle, but as has been mentioned and as shown below, several injections can be arranged to be performed, as well as only one.

The injection schedule is thus in the present example determined in advance in order to obtain a pressure development which meets the set criteria with regard to the maximum pressure amplitude that arises during combustion. A first injection is injected, and in step 304 it is determined whether said first injection has been performed, and if so, the procedure proceeds to step 305, where it is determined whether all the injections have been performed. Since this is not the case in the present example, the procedure proceeds to step 306 while being straightened up with a next injection. Furthermore, by using the pressure sensor 206, it is determined continuously, as at applicable intervals, e.g. every 0.1-10 crank angle degrees, radiating pressure in the combustion chamber.

The process of combustion can be generally described with the pressure change in the combustion chamber which the combustion gives rise to. The pressure change during a combustion cycle can be represented by a pressure pair, ie. a representation of how the pressure in the combustion chamber varies / changes during combustion. As long as the combustion proceeds as expected, the pressure in the combustion chamber will be equal to the initially estimated, but as soon as the pressure deviates from the estimated pressure, it will also be the way in which the pressure has changed, and clamed in all probability the maximum pressure amplitude that will arise during combustion, to deviate from the estimated value. In addition, the subsequent part of the combustion cycle, and thus pressure change, will be affected on the basis iv that changed conditions in the combustion chamber compared with expected conditions occur at e.g. a subsequent injection.

If the combustion after the first injection is impluedes has proceeded exactly as expected, the conditions in the combustion chamber will correspond to the conditions intended for the injection, as well as the resulting pressure change (pressure pair as below) in the combustion chamber will correspond to the expected pressure change. However, as soon as the conditions deviate from the intended conditions, the pressure change during combustion will deviate from the expected pressure change. Likewise, the subsequent part of the combustion will also be affected because the conditions prevailing in the combustion chamber, e.g. with respect to pi pressure / temperature, at the next injection will not correspond to expected conditions.

In practice, the actual pressure changes during the combustion (pressure pair) of natural shells will also in all probability deviate from the predicted pressure pair during the combustion process due to e.g. deviations from the modeled combustion. This is illustrated in Fig. 4, where a predicted pressure pair 401 for an example injection scheme is shown (very schematically), i.e. the expected pressure pair for the combustion chamber when injection is performed according to the selected injection profile. This prediction of the pressure pair can e.g. performed as described below.

Fig. 4 also shows an actual pressure pair 402 tram to the crank angle position which exits rowing position after the first combustion has been performed. In step 306, the pressure po in the combustion chamber is determined by using the pressure sensor 206 after the first injection has been dispensed, at the crank angle position. Preferably, the pressure in the combustion chamber is determined substantially continuously, such as e.g. at each crank angle, every tenth crank angle or at any other suitable interval throughout the combustion. As can be seen in Fig. 4, the actual pressure pair up to T1 deviates from the estimated pressure pair 401, likewise the actual pressure po at (1) 1 deviates from the estimated pressure Pest est according to the pressure pair 401. The above means that the resulting maximum pressure also deviated frail expected maximum pressure up to the crank angle position p.

Since the pressure po in the combustion chamber after the first injection has been performed differs from the corresponding estimated pressure n i-cp1 est at the crank angle position T1, the conditions in the combustion chamber at the time of the next injection insp2 will differ from the predicted and subsequent conditions. deviate from the predicted combustion if the previously established injection schedule would still be used. Thus, it is not at all certain that the desired limitation of the maximum pressure amplitude will be achieved during the combustion cycle. Thus, it is also not certain that it is the originally established injection scheme that constitutes the most preferred injection scheme in the case of achieving a combustion with undesired limitation of the pressure amplitude.

In step 307, it is determined whether the expected maximum pressure amplitude pmax_pred is expected to exceed any applicable pressure limit value p_thres where this may be predetermined and also be arranged to vary depending on other conditions such as current load, vehicle speed, etc. If the slope does not occur 19 to step 304 for performing the next injection, whereupon a new estimation of p is performed. If, on the other hand, pmax_pred is expected to exceed p_thres, the procedure proceeds to step 308 to re-establish an injection scheme in order to regulate the pressure amplitude, such as e.g. with the grind to try to limit the pressure amplitude to not exceed p_thres. The regulation can e.g. carried out according to the calculations shown below, alternatively according to other applicable calculations with a corresponding purpose, and repeated as below during the ongoing combustion cycle to change the injection schedule during ongoing combustion if the deviations actually prevailing in the combustion chamber deviate from predicted proportions, as usual during ongoing injection.

When estimating the expected maximum pressure amplitude according to the invention, e.g. a model is applied, which describes the pressure change that occurs during combustion. This model can be of different types, and e.g. consists of a dpdV data-driven model such as, for example— (90 1d) Utinjection strategy, Y dt) dt dar pow is the pressure at the previous determination, uinjection strategy is the control signal, ie. injection scheme, y generally constitutes the heat capacity ratio, ie. y = P = Pdar Cp — RC and / or C are generally developed and tabulated for different molecules, and by combustion chemistry Or kand, these tabulated values can be used together with the combustion chemistry to thereby calculate each molecule (eg water, nitrogen, oxygen etc.) impact on e.g. the total C -value, whereby this can be determined for the calculations above with good accuracy, in advance or during e.g. ongoing combustion. Alternatively, kanoch or (7, is appropriately approximated. Constitutes the volume change of the combustion chamber with time, which can be determined, for example, by means of V (0).

V (T) constitutes the volume of the combustion chamber as a function of crank angle, can advantageously be tabulated in the memory of the control system or alternatively be calculated in an appropriate manner, whereby it can also be calculated, and thereby also multiply by the combining speed of that combustion engine.

Thus, the pressure change velocity lp can be represented by such a model, which can be produced by determining the result for a starting number of input parameters, whereupon it can be tabulated for a starting number of ratios, such as different loads, speeds, air pressures, etc., as Or kdnt fOr fackmannen mom dp teknikomrAdet. By then accumulating (integrating) - over time, the pressure in the combustion chamber can be estimated, and by determining the pressure p and dt for each determination of dE Oven by comparing the obtained pressure p with earlier during the estimation obtained maximum pressure p, whereby the higher of these values are stored as a new maximum pressure, the maximum pressure during combustion can be estimated, whereby regulation can be performed if it is determined during the regulation that the pressure is expected to exceed a threshold value.

Another alternative, which constitutes the alternative applied in the present example, is the use of a physical model of the pressure of the pressure during combustion in the combustion chamber. This model can be any applicable model, and according to the present example, a heat release equation is applied as below.

Estimation of the variation in pressure during combustion can be done according to filing. The pressure p radiating in the combustion chamber can be determined by using said pressure sensor, whereby continuous sensor signals can give the measured value of the pressure p at appropriately taken intervals / crank angular degrees. Furthermore, e.g. when the pressure change rate is also taken into account, 1E is estimated for the part of the combustion that has already elapsed, and an actual maximum pressure change rate can be estimated for the part of the combustion that has already elapsed based on actual pressure data.

The pressure change can be determined as a function of time, as described above, but can also be expressed in crank angle degrees. dt dp; which meant an elimination of the dq internal combustion engine dependence in the calculations.

In cases where the pressure change rate is also taken into account in the regulation, the desired maximum pressure change rate dy, e.g. is stored for different speeds n so that e.g. represent a desired pressure change Over time. Alternatively edge.ex. determined as below and then dcp dp is multiplied by the combustion engine speed n fir to obtain. The present invention seeks to actively reduce, if necessary, the maximum pressure amplitude in the combustion chamber, which can be performed by estimating the expected maximum pressure amplitude for the subsequent part of the combustion cycle, where 22 e.g. a maximum color pressure amplitude can be determined, whereby the combustion can be regulated in order to keep the maximum pressure amplitude below any applicable pressure amplitude.

This also means that the pressure amplitude can be estimated for a number of different scenarios during combustion, such as different injection schedules, where the respective injection schedule will give rise to a specific pressure pair, such as e.g. the pressure pair shown in Fig. 4, and thus also different maximum pressure amplitudes during combustion.

When estimating the pressure pair, a model of the combustion can be used, and, as is known to those skilled in the art, the combustion can be modeled according to eq. (1): dQ - Kcalibrate (Q fuelQ) (1), where Kcalibrate is used to calibrate the model. Kcalibrate consists of a constant which is usually Or in the order of magnitude 01, but may also be arranged to assume second values, and which is determined individually cylinder for cylinder or for a certain motor or motor type, and depends in particular on the design of the injectors nozzles (diffusers).

QAd calculates the energy value for injected industry quantity, Q constitutes combustion energy quantity. The combustion dQ Or is thus proportional to the injected amount of fuel minus the amount of fuel consumed so far. The combustion dQ can alternatively be modeled by using another applicable model, where e.g. Other parameters can also be taken into account. For example. The combustion Above can constitute a function that depends on a model of the turbulence that arises during the supply of air / fuel, which can affect the combustion to varying degrees depending on the amount of air / fuel supplied. 23 Regarding the industry injections, these can e.g. is modeled as a sum of step functions: U = cp (t (tinj. start) k) (p (t - (tinj. end) k) (2) k = 0 BransleflOdet matt in supply mass m at an injection k, ie. how the fuel enters the combustion chamber during the time window u when the injection is performed, expressed in the time that elapses during the crank angle q interval that the injector is open, for a specific injection k can be modeled as: dm = f (m) u (3) days m constitutes injected industry volume, and f (m) eg depends on injection pressure, etc. f (m) can, for example, be measured or estimated in advance.

The energy value Quiv for the industry, such as diesel or petrol, is generally stated, whereby such a general statement can be used. The energy value can be specified above by e.g. industry's manufacturers, or be approximated for e.g. a country or region. The energy value can also be arranged to be estimated by the vehicle's control system. With the energy value, eq. (1) is released and the heat release Q as the combustion proceeds is determined.

Furthermore, by using a predictive heat release equation, the pressure change in the combustion chamber during the entire combustion can be estimated as: a, _ (c / QcIV) (y-1 p ——yp Tp4 (4) thp y-1 24, where y is the heat capacity ratio according to above.

The pressure p in the combustion chamber can be obtained by integrating eq. (4) according to: d (2 P - Pinitial + f dP - Pinitial + 1V (y dVyy— 1) 4 (5) 4 y— 4 Where pinitica constitutes an initial pressure, which before the start of the compression step of the combustion can e.g. When the estimation is performed at a later time during the combustion cycle, such as estimation in step 307 after an injection has been performed, Pinitial can be made with the old radius and by means of the pressure sensor 206 the pressure determined, i.e. p (pl in the present example. Thus, both the pressure p (and also the pressure derivative) in the combustion chamber can be estimated for the whole combustion, i.e. a related curve corresponding to curve 401 in Fig. 4 can be estimated.

Thus, by utilizing eq. (4) p, either as a function of crank angle or time by multiplying by speed as above, is estimated for the remainder of the combustion cycle, or even an entire combustion cycle if the estimation is performed before fuel injection is started, where p at each iteration of equations 4-5 can be compared with p_thres to determine whether the pressure on is expected to exceed p_thres during combustion. Thus, the actual maximum pressure that is expected to arise does not need to be estimated, but the estimation can, according to one embodiment, be interrupted as soon as it is found that the expected exceed p_thres during combustion.

Alternatively, the maximum pressure that can be achieved during the estimation can be obtained by performing the integration as long as p (k + 1)> p (k), where k, k + 1 etc. are consecutive times / crank angle positions. Thus, as long as the pressure rises, the integration continues, while the integration can be interrupted when p (k + 1) ‹p (k), since the pressure dl has begun to decrease. The maximum pressure can then be compared with the threshold value p_thres.

If so, the procedure proceeds as above to step 308 may establish a new injection strategy, since regulating the pressure in the combustion chamber e.g. can be performed by regulating the industry injection, and by performing in step 308 estimating the pressure for a number of different injection schedules with e.g. varying injection times and / or injection lengths and / or number of injections and / or times between injections, estimated maximum pressure amplitudes for different injection alternatives can be compared and thus an injection schedule established as possible to reduce dp_thres during combustion, preferably by shaft still retained.

Thus, the work requested during the combustion can be determined above, which e.g. may be determined by a somewhat superior process such as Is responsible for the propulsion of the vehicle, whereby the regulation may have as a requirement that the resulting work during combustion essentially corresponds to the said requested work, or at least a part of it, such as e.g. at least half of the work requested.

Thus, in step 308, an injection schedule may be established, such as an injection schedule among a plurality of defined 26 injection schedules, where this injection schedule may be determined individually cylinder by cylinder based on sensor signals from at least one pressure sensor in each combustion chamber.

Regarding the mentioned injection schedules, it can e.g. there are a plurality of predefined injection schedules, whereby calculations of the above type can be performed for each of these available injection schedules. Alternatively, the calculations can be performed for the injection schedules that for some reason are most likely to result in the desired law pressure amplitude.

Until now, entire injection schedules for residual combustion have been evaluated, but the evaluation can also be arranged to be performed for only the next injection after a previous injection, whereby later injections can be handled afterwards. The injection schedule selected in step 308 can be suedes from the next injection only.

When the injection scheme has been selected in step 308, the procedure returns to step 304, performing the next injection, which also gives rise to a combustion, and thus a heat release and a pressure pair, where this is also likely to deviate from the previously predicted pressure pair. This also means that the combustion, even in subsequent injections, is likely to be affected by radiating conditions in the combustion chamber when the injection is started.

Thus, in step 308, after a subsequent injection has been performed, again a new injection strategy for the remaining injections, alternatively the subsequent injection, can be calculated by means of the above equations, 27 whereby the procedure then returns to step 304 for carrying out the subsequent injection. new injection strategy developed in step 308, still taking into account the work to be performed during the firing, which is thus normally controlled by some overriding process, e.g. in response to a request for a certain driving force from the driver of the vehicle or other function in the vehicle's steering system, such as e.g. a cruise control function. The control can thus be arranged to be carried out after each injection and when all the injections have been carried out, the process from step 305 to step 301 returns to control of a subsequent combustion cycle. According to one embodiment, however, the process is stopped as soon as the maximum pressure of the combustion has been reached, which can be determined as below. The noise emitted during combustion depends primarily on the pressure build-up and to a lesser extent on the subsequent pressure drop. For this reason, the control can thus be interrupted when the maximum pressure of the combustion has been reached.

In the above calculations, after each injection, the current pressure determination po is used by using the pressure sensor 206 as Pinitai as above to predict maximum pressure amplitude to determine, if necessary, a new injection schedule according to the now prevailing conditions in the combustion chamber, but now further with data obtained a bit into the combustion. Ie. po after the first combustion and in a corresponding manner determined po for subsequent injections, whereby Pinitial thus changes in calculations during the combustion cycle, and whereby the fuel injection is adapted to radiating conditions after each injection, with the consequence that the injection schedule can be changed after each injection. The present invention thus provides a method which adapts the combustion as the combustion proceeds, and generally comprises, based on a first parameter value determined after a first part of the combustion has been carried out, regulating subsequent part of the combustion during one and the same combustion cycle, the combustion being controlled by with respect to the maximum pressure during the combustion process.

As above, maximum pressure amplitude suedes can be estimated for a variety of alternative injection schemes for residual injections, with an injection scheme resulting in the most advantageous, such as e.g. the lowest pressure amplitude can be selected when performing the next injection. In cases where several injection schemes / control alternatives meet the set conditions, other parameters can be used to select which of these is to be used. There may also be other reasons for simultaneously regulating also based on other parameters. For example. Injection schedule, except based on pressure amplitude, can be partly selected Also based on one or more of the perspectives pressure change rate, heat loss, exhaust temperature, exhausted work in the combustion chamber, or nitrogen oxides generated during combustion as additional criteria, where such determination can be performed according to any of the below patent applications. Specifically, the parallel application "PROCEDURE OCI-I SYSTEM FOR REGULATING A COMBUSTION MOTCR I" (Swedish patent application, application number: 1350506-0) discloses a procedure for regulating subsequent combustion based on an estimated maximum pressure change rate.

Furthermore, the parallel application "PROCEDURE OCR SYSTEM FOR REGULATING A COMBUSTION MCTCR II" (Swedish patent application, 29 application number: 1350507-8) said subsequent combustion resulting temperature.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLING AN COMBUSTION ENGINE III" shows a method for regulating combustion during a first combustion cycle during a subsequent part of said first combustion cycle with respect to a work performed during combustion.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLING AN COMBUSTION ENGINE IV" shows a procedure for controlling combustion during a first combustion cycle during a subsequent part of said first combustion cycle with respect to a representation of a heat loss resulting in said combustion.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLING AN COMBUSTION ENGINE VI" shows a procedure for estimating during a first combustion cycle a first mat of nitrogen oxides resulting from combustion during said first combustion cycle, and based on said first mat, regulating a combustion engine. part of the said first combustion cycle.

According to the present invention, the combustion is thus adapted during ongoing combustion if necessary based on deviations from the predicted combustion, and according to one embodiment, an evaluation of the combustion is performed each time an injection has been performed as long as further injections are to be performed.

According to the procedure described above, the injection schedule at the beginning of the combustion cycle has been determined based on tabulated values, but according to one embodiment the injection strategy can already be determined before the industry injection is started in the manner described above, thus also the first injection is performed according to the above schedule.

The regulation has so far been described in one way in which the properties of a subsequent injection are determined based on prevailing conditions in the combustion chamber after the previous injection. However, the control can also be arranged to be performed continuously, whereby pressure determinations can be performed with the aid of the pressure sensor also during pagan injection, and whereby the injection schedule can be calculated and corrected by others until the next injection is started. Alternatively, even the ongoing injection may be affected by protruding changes in the injection schedule. In violet cases where several shorter injections are performed. For example. an ongoing injection can be interrupted if the pressure amplitude becomes too high. The injection can also consist of a single longer injection, whereby changes of ongoing injection can be performed continuously, e.g. by so-called rate shaping, e.g. by changing the opening area of the injection nozzle and / or the pressure at which the fuel is injected based on estimates and the measured pressure value during the injection. Furthermore, fuel supply during combustion can include two fuel injections, where e.g. only the second or both injections are regulated e.g. with the help of rate shaping. Rate shaping can also be applied in the case where three or more injections are performed. 31 Regarding the injection strategies to be evaluated, these can be developed in different ways. For example. different distributions between injections can be evaluated, and e.g. can injected industry quantity be redistributed between subsequent injections and / or can the injection time be changed for one or more subsequent injections, where the view can be taken to ev. restrictions with regard to e.g. minimum permitted length or industry quantity for an industry injection.

Instead of evaluating a number of specific injection schedules, the method may be arranged to perform e.g. the above calculations for a number of conceivable scenarios, where the calculations can be performed for different injection lengths / quantities / times for the different injections, with corresponding changes in released energy.

The more industry injections that are carried out during an incineration cycle, the more parameters can be changed, while at the same time tiring work should be maintained. With a large number of injections, the regulation can therefore be relatively complex, since a large number of parameters can be varied and thus would need to be evaluated. For example. a very large number of injections can be arranged to be performed during one and the same combustion cycle, such as a dozen, or even about a hundred injections.

In such situations, and in addition to others as above, there may be several substantially equivalent injection strategies, which result in substantially the same maximum pressure amplitude, or which meet the set requirements / requirements for the pressure amplitude. This introduces an undesirable complexity in the calculations. 32 According to one embodiment, a control is applied where the nearest injection / injection is considered a separate injection at the time, and subsequent fuel injections as a single additional "virtual" injection, whereby fuel can be distributed between these "two" injections in one way or another. that the maximum pressure during the first combustion is not expected to exceed the desired levels. This is exemplified in Fig. 5A, where the injection 501 corresponds to the injection as above, the injection 502 corresponds to the injection 2 as above, and where the remaining injections 503-505 are treated as a single virtual injection 506, i.e. the injection 506 is treated as an injection with an industry quantity substantially corresponding to the total industry length for the injections 503-505, and where distribution can take place between the injection 502 and the virtual injection 506. By proceeding in this way, the displacement which takes place between insp2 and subsequent injections is not specifically distributed between the injections 503-505, but is distributed at this stage between the injection 502 and the "virtual" injection 506, respectively.

After the injection 502 has been performed, if necessary, the procedure is repeated as above with a new determination of the injection schedule to try to reduce the pressure amplitude if necessary, but d6 with the injection 503 as a separate injection, see Fig. 5B, and injection 504, 505 together constitute a virtual injection at distribution as above.

In Fig. 5A, the virtual injection 506 is three injections, but as will be appreciated, the virtual injection 506 may initially comprise more than three injections, such as 10 injections or 100 injections, depending on how many injections are intended to be made. is carried out during the combustion cycle, the procedure being repeated until all the injections have been carried out. According to one embodiment, however, the process is interrupted when the maximum pressure has been reached and the pressure in the combustion chamber Ater has begun to fall because the maximum pressure amplitude during combustion can no longer be affected.

It is also possible to use e.g. an MPC (Model Predictive Control) control when controlling according to the invention.

An example of an MPC control is shown in Fig. 6, where the reference curve 603 corresponds to expected pressure development at the heat release during the combustion cycle, i.e. the result of eq. (5) above for selected injection schedule. Curve 603 can e.g. consists of a realistically achievable (lowest) level during the combustion cycle for the maximum pressure at the current load and radiating speed, and can e.g. determined in advance, e.g. by applicable calculations and / or feeds on the motor type, whereby this data can be stored in the control system memory as a function of e.g. speed and load.

This also means that the combustion does not have to be controlled only against a pressure which, as usual, radiates, but can also be arranged to be controlled against a expected maximum pressure, such as e.g. curve 603 in Fig. 6, whereby habit injection may be intended to result in a combustion corresponding to curve 603.

The solid curve 602 up to time k represents the actual development of the pressure which has hitherto arisen and which has been calculated as above with the aid of actual data from the crank angle-resolved pressure sensor. Curve 601 represents the estimated, i.e. expected, the development of the pressure in the combustion chamber based on the predicted 34 injection profile. Dashed injections 605, 606, 607 represent the predicted control signal, i.e. the injection profile used is applied, and 608, 609 represent already challenging injections.

The predicted injection profile is updated at appropriate intervals, such as e.g. after each challenge injection, to reach the final value which is sought and given by the reference screw 603, and where the next injection is determined based on the prevailing conditions in relation to the estimated pressure development.

Thus, the present invention provides a method which allows a very good control of a combustion process, and which adapts the combustion during ongoing combustion to obtain a combustion with controlled pressure change and associated associated emitted sound.

According to the above, the combustion can be regulated during an ongoing combustion cycle. According to one embodiment, however, the estimation is performed for a combustion cycle, whereby a subsequent combustion cycle can then be regulated based on the estimation for the previous combustion cycle.

The invention has been exemplified above in a manner in which a pressure sensor 206 is used to determine a pressure in the combustion chamber. As an alternative to using pressure sensors, one (or more) other sensors can be used, such as e.g. high-resolution ion current sensors, knock sensors or strain gauges, whereby the pressure of the combustion chamber can be modeled by using sensor signals from such sensors. It is possible to combine different types of sensors, e.g. to obtain a more accurate estimation of the pressure in the combustion chamber, and / or to use other applicable sensors, where the sensor signals are converted to the corresponding pressure for use in control as above.

Furthermore, in the above description, only industry injection has been regulated. Instead of regulating only the amount of fuel supplied, the pressure during combustion can be arranged to be regulated by means of e.g. exhaust valves, whereby injection can be carried out according to a predetermined schedule, but where the exhaust valves are used to regulate the pressure in the combustion chamber.

Furthermore, the control can be performed with any applicable type of regulator, or e.g. using state models and state feedback (for example, line programming, the LQG method or similar).

The inventive method for controlling the internal combustion engine can also be combined with sensor signals from other sensor systems where resolution at the crank angle level is not available, such as e.g. other pressure sensors, NOx sensors, NH3 sensors, PM sensors, oxygen sensors and / or temperature sensors etc., which input signals e.g. can be used as input parameters when estimating e.g. maximum pressure by using data-driven models instead of models of the type described above.

Furthermore, the present invention cyan has been exemplified in connection with vehicles. The invention is, however, also applicable to arbitrary vessels / processes where combustion control as above is applicable, such as e.g. water or aircraft with combustion processes as above.

It should also be noted that the system may be modified according to various embodiments of the method of the invention (and vice versa) and that the present invention is not in any way limited to the above-described embodiments of the method of the invention, but relates to and includes all embodiments of the appended claims. the scope of protection of the independent requirements.

Claims (40)

A method of controlling an internal combustion engine (101), said combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said combustion chamber (201), said combustion in said combustion chamber (201). ) takes place in combustion cycles, the process being characterized in that: 1. during a first combustion cycle, determine at least one first parameter value for a quantity in combustion in said combustion chamber (201), 2. based on said first parameter value, estimate a representation of a pressure amplitude resulting in said first combustion cycle and in said combustion chamber (201) , and 3. based on the said estimated pressure amplitude, regulate subsequent combustion. The method of claim 1, wherein said subsequent combustion is a subsequent portion of said first combustion cycle. A method according to claim 1 or 2, further comprising determining said first parameter value during a first part of said combustion cycle, and wherein said subsequent combustion is constituted by a part of said first combustion cycle following said first part of said first combustion cycle. A method according to any one of claims 2-3, further comprising: 1. based on said first parameter, estimating a pressure amplitude resulting in said subsequent part of said first combustion cycle in said 38 combustion chambers (201), and - based on said estimated pressure amplitude, regulate the color combustion for the said subsequent part of the said first combustion cycle. A method according to claim 1, wherein said subsequent combustion consists of a combustion cycle following said first combustion cycle. A method according to any one of claims 1-5, wherein said estimated pressure amplitude is constituted by a maximum pressure amplitude estimated during said first combustion cycle and in said combustion chamber (201). A method according to any one of the preceding claims, further comprising determining At least one control parameter for controlling said subsequent combustion, said control parameter constituting a control parameter where an expected estimated maximum pressure amplitude is less than a first pressure amplitude when controlling according to said control parameter. A method according to any one of the preceding claims, further comprising determining at least one control parameter for controlling said subsequent combustion, said control parameter being a control parameter where an expected estimated maximum pressure change rate is less than a first pressure change rate when controlling according to said control pair. A method according to any one of the preceding claims, further comprising: - determining a resultant work requested in said combustion, and - determining at least one control parameter for controlling said subsequent combustion, said control parameter constituting a control parameter where an estimated resultant work yid said combustion Combustion corresponds at least to the haiften of the said requested work. A method according to claim 9, wherein said control parameter constitutes a control parameter where an estimated resultant work in said combustion substantially corresponds to said desired work. A method according to claim 9 or 10, wherein said work said in said combustion is determined based on a request for work performed by said combustion engine. A method according to any one of the preceding claims, wherein said pressure amplitude is estimated by using one or more of: data driven model, empirical model, physical model. A method according to any one of the preceding claims, wherein said pressure amplitude is estimated by using an estimation of a heat release during said combustion. A method according to claim 13, wherein said pressure amplitude is estimated by estimating a pressure pair resulting from the combustion. The method of claim 13 or 14, further comprising estimating said heat release based on the amount of fuel supplied to said combustion. A method according to any one of the preceding claims, wherein said first parameter value represents a pressure radiating in said combustion chamber (201). A method according to any one of the preceding claims, further comprising controlling combustion during said subsequent part of said first combustion cycle by controlling the supply of bran to said combustion chamber (201). A method according to any preceding claim, further comprising: 1. estimating an expected maximum pressure amplitude for at least two control alternatives for said subsequent combustion by utilizing said first parameter value, and 2. selecting a control alternative from said plurality of control alternatives for controlling the combustion during said subsequent combustion based on said expected maximum pressure amplitude. The method of claim 18, further comprising: 1. determining whether any of said control alternatives constitutes a control alternative where the estimated maximum pressure amplitude when regulating according to said control alternative is less than a first pressure amplitude, and 2. if so, selecting a control alternative having an estimated maximum pressure amplitude is less than a first pressure amplitude. The method of claim 18 or 19, further comprising selecting the control alternative that is expected to result in at least maximum pressure amplitude during said subsequent combustion. A method according to any one of claims 18-20, wherein said control alternative consists of alternatives for supplying fuel during said subsequent part of said combustion cycle. 41 A method according to any one of claims 18-21, wherein said supply of fuel to said combustion chamber (201) is regulated by controlling fuel injection by means of at least one fuel injector (202). A method according to any one of claims 18-22, wherein at least one fuel injection is performed during said subsequent part of said combustion cycle, wherein in said control the fuel quantity and / or injection length and / or injection pressure and / or time between injections is regulated for said fuel injection. A method according to any one of claims 18-23, wherein at least two fuel injections are performed during said subsequent part of said combustion cycle, said combustion also being controlled after said first of said at least two fuel injections. A method according to any one of claims 18-24, wherein in controlling said combustion at least three fuel injections are performed during said subsequent part of said combustion process, wherein in determining control parameters for a first of said at least three fuel injections, remaining fuel injections are treated as single fuel injections. injection. A method according to any one of claims 18-25, wherein controlling the combustion during said subsequent part of said first combustion cycle is performed at least in part by controlling the fuel injected into said combustion chamber (201) during a pending fuel injection. A method according to any one of claims 18-26, further comprising, when regulating the fuel injected into said 42 combustion chamber (201), changing a distribution of fuel quantities between at least two fuel injections. A method according to any one of claims 18-27, further comprising applying a predetermined injection of fuel at the beginning of the combustion cycle, wherein control is performed after a first injection has at least started, but before fuel injection during said first combustion cycle has ended. A method according to any preceding claim, further comprising performing a first fuel injection to said combustion chamber (201) during a first portion of a first combustion cycle, and at least a second fuel injection during a subsequent portion of said combustion cycle, wherein control parameters for said second combustion cycle determined after the said first fuel injection has been carried out at least in part. A method according to any one of the preceding claims, further comprising: - determining whether the pressure during said combustion during said combustion cycle has reached maximum pressure during said combustion cycle, and - interrupting said process when maximum pressure has been reached. of the preceding requirements, further pressure amplitude is estimated for 31. A method according to ridgot comprising, when a said combustion: - interrupt estimation when estimation has been performed up to a point where a maximum pressure amplitude during the combustion is expected. 43 A method according to any one of the preceding claims, further comprising controlling combustion during said subsequent part of said first combustion cycle by regulating one or more valves operating at said combustion chamber (201). A method according to any one of the preceding claims, wherein said control is performed for a plurality of consecutive combustion cycles. A method according to any one of the preceding claims, wherein said first parameter value for a quantity in combustion in said combustion chamber (201) is determined at least at each crank angle, every tenth of each crank angle or every hundredth of each crank angle. A method according to any one of the preceding claims, wherein said first parameter is determined by using one or more of the group: cylinder pressure sensor, knock sensor, strain sensor, speed sensor, ion current sensor. A computer program comprising program code, which when said program code is executed in a computer causes said computer to perform the procedure according to any of claims 1-35. A computer program product comprising a computer readable medium and a computer program according to claim 36, wherein said computer program is included in said computer readable medium. A system for controlling an internal combustion engine (101), said combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said combustion chamber (201), wherein combustion takes place in said combustion chamber (201). in combustion cycles, the method being characterized in that the system comprises: 44 - means for determining during a first combustion cycle at least one first parameter value regarding a quantity in combustion in said combustion chamber (201), - means (115) for being based on said first parameter value estimating a representation of a pressure amplitude resulting in said first combustion cycle and in said combustion chamber (201), and means (115) for regulating subsequent combustion based on said estimated pressure amplitude. A system according to claim 38, characterized in that said internal combustion engine consists of flakes from the group: vehicle engine, marine engine, industrial engine. A vehicle (100), characterized in that it comprises a system according to claim 38 or 39.