SE537305C2 - 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 the said combustion chamber (201) takes place in combustion cycles. The method is 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 one 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.

Description

FIELD OF THE INVENTION Field of the Invention systems 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 a prior art.

Concerning vehicles in general and At least in some heavy vehicles in particular, there is a constant development in pursuit of industry efficiency and reduced exhaust emissions. Due to e.g. Increased government interests regarding pollution and air quality in e.g. urban areas, emission standards and rules have been developed in many jurisdictions. When driving heavy vehicles, such as lorries, buses and the like. Over time, the vehicle economy has also had a major 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 are included. Thus, it is important for each of these areas to try to reduce the cost as much as possible. 1 537 30 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 a lot of work is also often put into driver millions. 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 respect, there may also be laws and regulations that regulate permissible 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 process according to claim 1.

The present invention relates to a method of controlling an internal combustion engine, said internal 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 by: - during a first combustion cycle, determining at least one first parameter value for a quantity during combustion in said combustion chamber, based on said first parameter value, estimating a representation of a result during a first combustion cycle and in said combustion result. pressure amplitude, such as a maximum pressure amplitude, and - based on the said estimated pressure amplitude, regulate subsequent combustion.

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

In vehicles, as is the case, many noises / noises are made, and one main source is the internal combustion engine. The noise produced by an internal combustion engine depends to a large extent on the combustion in the combustion chamber of the internal combustion engine, and in particular 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 especially when the pressure rises rapidly.

According to the present invention, the combustion is regulated with respect to the pressure level that 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 mode 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 may be arranged to be carried out individually for each cylinder, and the combustion may be regulated for a subsequent combustion cycle based on information from one or more preceding combustion cycles.

According to one embodiment, a representation is estimated the maximum pressure amplitude that is expected to result during a combustion cycle, wherein the combustion for a subsequent combustion cycle is regulated based on this estimation, and wherein 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, wherein the invention provides a control of an ongoing combustion process where control can be performed during ongoing combustion in order to e.g. prevent an undesired high pressure amplitude from occurring.

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 Thus e.g. Releasing 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 establishing an injection strategy for application in a subsequent injection during the combustion cycle, whereby in determining the injection strategy an 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, where an injection strategy is chosen which is not expected to result in an undesired pressure development during combustion. For example. If an injection strategy can be chosen that is expected to result in a maximum pressure amplitude that is less than the applicable spruce value for the maximum pressure, where this spruce value amounts to some applicable maximum pressure such as e.g. expected to result in a sound output level which in turn is below the applicable sound level of the flag, or meets another criterion regarding sound output.

The method of the present invention can e.g. implemented using one or more FPGAs (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, and 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 coupling 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. Fig. 1A shows only one shaft with drive wheels 113, 114, 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 includes an exhaust system with a post-treatment system 200 for conventional 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 to supply the desired amount of fuel at the desired time in the combustion cycle, as at a specific piston position (crank angle degree) in the case of a piston engine, to the internal combustion engine.

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 is in the present example a six-cylinder internal combustion engine, and can generally be constituted by an engine with an arbitrary 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 thus used 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 actuators of the injectors 202 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 that is actually to be injected at a given time, e.g. based on the prevailing operating conditions of the vehicle 100.

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) were supplied with fuel from a common fuel line 204 (Common Rail), which with the help of a fuel pump 205 was filled with fuel from a fuel tank (not shown) at the same time as the fuel in the furnace. 204, also with the aid of the fuel pump 205, is pressurized to a certain pressure. The highly pressurized fuel in the common tube 204 is then injected into the combustion chamber 201 of the internal combustion engine 101 at the 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 one 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 5th or habit crank angle degree or other applicable interval, 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 previous combustion cycle, i.e. the calculation from a previous combustion cycle is used in controlling 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 combustion chamber of the internal combustion engine, and in particular on the manner in which the pressure changes during combustion. According to the invention, the combustion is regulated above all with respect to the maximum pressure that is allowed 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 in particular at pressure boiling.

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

Generally, control systems in modern vehicles consist of a communication bus system consisting of one or more communication buses for interconnecting a number of electronic control units (ECUs) such as the control unit, or controller, 115, and various components arranged on the vehicle. As an edge, such control systems may comprise a large 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, in Figs. 1A-B, only the motor control unit 115 in which the present invention is implemented in the embodiment shown is shown. However, the invention may 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 present 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 solutions are attenuated and vd1 can handle calculations according to the present invention.

The function of the control unit 115 (or the control unit (s) to 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 control unit causes the computer / control unit 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, cid "the computer program product comprises a suitable storage medium 121 (see Fig. 1B) with the computer program stored on said storage medium 121. The said digital storage medium 121 may, for example, be constituted by someone 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, whereby the computer program is executed. By changing the instructions of the 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 calculating unit 120, which may be constituted by e.g. any suitable 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 1 need to be able to perform calculations. The bending unit 120 is then arranged to store partial or final results of calculations 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 inputs and outputs may contain waveforms, pulses, or other attributes, which of the input signals 122, 125 for receiving input signals may be detected as information for processing the calculation unit 120. The devices 123, 124 for transmitting output signals are arranged to convert calculation results from the calculation 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 receiving and transmitting input and output signals, respectively, may be one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Oriented Systems 11 537 30 Transport), or flag other bus configuration; or by a wireless connection.

Returning to the process 300 shown in Fig. 3, the process starts in step 301, where it is determined whether the control according to the invention of the combustion process is to be carried out. The regulation according to the invention can e.g. be 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 undesirable for regulation to be carried out based on factors other than the sound emitted in the first place. According to one embodiment, control of the combustion is performed simultaneously with respect to emitted sound during combustion and at least one additional control parameter. For example. a balancing can be made, where the prioritization of the control parameters when fulfilling the desired control result e.g. may be arranged to be controlled according to the flag applicable function function.

The method according to the present invention consists in a method for controlling the internal combustion engine 101 while combustion takes place in said combustion chamber 201 in combustion cycles. As is edge, the term combustion cycle is defined as the steps a combustion at 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 also includes cycles where no fuel is actually injected, but where the internal combustion engine is driven at a certain speed, such as by the vehicle's drive wheel via the driveline at e.g. relaxation. Ie. even if no injection of fuel is carried out, a combustion cycle still takes place for e.g. every two vary (for four-stroke engine), or e.g. vane vary (two-stroke engine), which rotates the output shaft 12 537 30 of the internal combustion engine. The same applies to other types of internal combustion engines.

In step 302, it is determined whether or not a combustion cycle will be started here, and when so, the process proceeds to step 303 while 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 a desired 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.

General (jailer that the supply of the amount of fuel 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, eg depending on the work (torque) that the internal combustion engine is to perform during the combustion cycle, since changes to the established injection schedule are not performed during an ongoing combustion cycle according to prior art.For-specific injection schedules may, for example, be tabulated in the vehicle control system for a large number of operating cases, such as different engine speeds, different working conditions, different combustion air pressures, etc. where tabulated data may, for example, have been produced by appropriate tests / feeds in, for example, the development of an internal combustion engine and / or vehicle, whereby an appropriate injection schedule / control alternative can be selected based on prevailing conditions, and where the injection schedule may be selected or pre-adapted for to, for example, result in an expected maximum pressure amplitude that is less than the applicable pressure gauge value. 13 537 30 These injection schemes / 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 large 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 can also be developed for the purpose of fulfilling other goals as well, such as delivering the desired work, resulting in a certain maximum heat loss, a certain exhaust temperature, etc., whereby the injections can thus 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 (requested) by some superior / other process, such as e.g. based on a request for propulsion from the driver of the vehicle 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 excessively low 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 preferred injection schedule as usual, it may be advantageous to select an injection schedule for a combustion cycle by some type of look-up and thereby reduce the calculation load, calculating as follows only after injection has been started. 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, control according to the invention being performed only after fuel injection has been started during the combustion cycle, such as only after at least one injection has been performed during the combustion cycle or at least 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. Injection systems with 5-10 fuel injections / combustion occur, but the number of fuel injections can also be significantly larger than that, 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 of the organs with which the injection is performed, ie. in the case of Common Rail systems of how quickly the injectors can be opened shut down. 537 30 According to the present example, at least two fuel injections are performed 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 scheme is thus in the present example determined in advance in order to obtain a pressure development which meets set criteria with regard to the maximum pressure amplitude that arises during combustion. A first injection is performed, 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 sA is not yet the case in the present example, the process 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, increasing pressure in the combustion chamber.

The combustion process can be generally described with the pressure change in the combustion chamber that the combustion gives rise to. The pressure change during a combustion cycle can be represented by a pressure gauge, ie. a representation of how the pressure in the combustion chamber varies / changes during combustion. As the combustion progresses 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 set to which the pressure has changed, and thus in all probability also 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 due to changed conditions in the combustion chamber compared to expected conditions at e.g. a subsequent injection.

If the combustion after the first injection has thus 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 point. 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 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 up to the crank angle position cp, which constitutes a rowing position after the first combustion has been carried out. In step 306, the pressure p (pli of the combustion chamber is determined by using the pressure sensor 206 after the first injection has been performed), at the crank angle position p1. Preferably, the pressure in the combustion chamber is determined substantially continuously, such as at each crank angle, As can be seen in Fig. 4, the actual pressure gauge deviates up to pi from the estimated pressure gauge 401, as well as the actual pressure pi at pi deviates from the estimated pressure n, 91_est according to the pressure gauge 401. The above meant that the resulting maximum pressure has also deviated from the expected maximum pressure up to the crank angle position 91.

Since the pressure on the combustion chamber after the first injection has been carried out differs from the corresponding estimated pressure on (pl_est at the crank angle position pi, the conditions in the combustion chamber at the time of the next injection insp2 will differ from predicted conditions after which different conditions will occur). thus, it is not certain that the desired limitation of the maximum pressure amplitude will be achieved during the combustion cycle, so it is not certain that it is the originally established injection scheme that constitutes the most preferred injection scheme. at the penalty of achieving a combustion with the desired 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 test 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. SA lange as is not the case 18 537 30 Returns the procedure to step 304 for performing the next injection, then performing a new estimation of p. If, on the other hand, pmax_pred is expected to exceed p_thres, the procedure proceeds to step 308 to establish an injection scheme again 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. performed 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 necessary if the conditions actually radiating in the combustion chamber deviate from predicted conditions, as after each injection 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. is made up of a dpdV data-driven model such as = f (poia, Ujnjectiongtrategy, y,), dt dar Poiä is the pressure at the previous determination, uinjection strategy is the control signal, ie. injection schedule, Cfl y generally constitutes the heat capacity ratio, ie. 7 = - ===, where C7v Cp-R C and / or C, are generally developed and tabulated for different molecules, and since the combustion chemistry is known, these tabulated values can be used together with the combustion chemistry to thereby calculate each molecule (t. 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, Cp and or CC can be approximated appropriately. dV constitutes the volume change of the combustion chamber with time, dt which e.g. can be determined with the aid of V (v) constitutes the volume of the combustion chamber as a function of crank angle, can advantageously be tabulated in the control system memory or alternatively calculated in a suitable way, whereby also dtp dV can be calculated, and thus also TIT by multiplying by the combustion engine's radiating speed. dp Thus, the rate of change of pressure can be represented by dt such a model, which can be produced by determining results for a large number of input parameters, whereby 1/2 then dt can be tabulated for a starting number of ratios, such as different loads, speeds, air pressures, etc., as is edge for the professional mom technical area. By then accumulating (integrating) dp over dt time, the pressure in the combustion chamber can be estimated, and by for each determination of dp also determining the pressure p and dt by comparing the obtained pressure p with earlier during the estimation obtained the maximum pressure p, whereby the 1- 15g 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 change in pressure during combustion in the combustion chamber. This model can be made of 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 performed as follows. 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, it is estimated for that part of the combustion which has already passed, and an actual maximum pressure change rate can be estimated for the part of the combustion which has already passed based on actual pressure data.

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

In cases where the pressure change speed is also taken into account in the regulation, the desired maximum pressure change speed dcp can e.g. is stored for different speeds n so that e.g. represent a desired pressure change Over time. Alternatively edge.ex. The present invention strives 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 21 537 30 e.g. a maximum expected pressure amplitude can be determined, whereby the combustion can be regulated in order to keep the maximum pressure amplitude below the flag 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 the edge for the person skilled in the art, the combustion can be modeled according to eq. (1): dQ = Kcaltbrate (Q fuel - Q) (1), where Kcal ibrate is used to calibrate the model. K -calibrate consists of a constant which is usually of the order of 01, but may also be arranged to assume second values, and which is determined individually cylinder by cylinder or for a particular engine or engine type, and depends in particular on the design of the injectors nozzles (diffusers ).

Qfl is the energy value for injected industry volume, Q is the fuel energy volume. The combustion dQ 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 can also constitute a function that depends on a model Over 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. 22 537 30 Regarding the industry injections, these can e.g. is modeled as a sum of step functions: U = (tinj. start) k) (1) (t (tinj. end) k) (2) k = 0 Bransleflodet matt in tillford 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 degree p -interval that the injector is open, for a specific injection k can be modeled as: dm dt = f (m) u (3) where m constitutes injected industry volume, and f (m) e.g. depends on injection pressure etc. f (m) can e.g. be measured or estimated in advance.

The energy value 0, LHV for the industry, such as diesel or petrol, is generally stated, whereby such a general statement can be used. The energy value can also be specifically specified 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: (dQy p dV) (y-1) (4) dP = cicp y — 1 thp I v 23 537 30, where y constitutes the heat capacity ratio according to above.

The pressure p in the combustion chamber can be obtained by integrating eq. (4) according to: dQ y dVvy — l) chp P Pinitial f dP = Pinitialy 1 P clip) (5) Dar Pinitiat constitutes an initial pressure, which before the start of the compression step of the combustion e.g. may be due to the ambient pressure of non-turbocharged internal combustion engines, or a prevailing combustion air pressure of a turbocharged engine. When estimation is performed at a later time during the combustion cycle, such as estimation in step 307 after an injection has been performed, n rinitial can be made from the dA rAdande and with the aid of the pressure sensor 206 determined the pressure, i.e. 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 the 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 also for an entire combustion cycle if the estimation is performed before fuel injection pAborges, where p by habit 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 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 p is expected to exceed p_thres during combustion. 24 537 30 Alternatively, the maximum pressure expected to be reached 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. As long as the pressure rises, the integration thus continues, while the integration can be interrupted when p (k + 1) ‹p (k), since the pressure has then begun to drop. The maximum pressure can then be compared with the threshold value p_thres.

If so, the procedure as above proceeds to step 308 to establish an escape 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, it is also possible to establish a work requested during the combustion, 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 in combustion essentially corresponds to the 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 537 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 flagon 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 scheme selected in step 308 can thus consist of only the next injection.

Once the injection scheme has been selected in step 308, the process returns to step 304 for performing the next injection, which also gives rise to a combustion, and clamed a heat release and a pressure pair, where also this is 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 is performed here, a new injection strategy for the remaining injections, alternatively the subsequent injection, can be calculated by means of the above equations, whereby the procedure then returns to step 304 for performing subsequent injection. according to the new injection strategy developed in step 308, still taking into account the work to be performed during the combustion, which is thus normally controlled by the flake overriding process, e.g. in response to a request for a certain driving force from the vehicle's driver or another 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 procedure returns from step 305 to step 301 for controlling 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 sound emitted during combustion depends above all 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 is used by using the pressure sensor 206 as the initial as above to predict any pressure amplitude to determine, if necessary, a new injection schedule according to the now prevailing conditions in the combustion chamber, but now further data obtained a bit into the combustion. Ie. Pi after the first combustion and correspondingly set p9, for subsequent injections, thus changing 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 change 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, wherein the combustion is regulated with respect to the maximum pressure during the combustion process.

According to the above, maximum pressure amplitude can thus be estimated for a number of different alternative injection schemes for the remaining injections, whereby an injection scheme which results 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. In addition to pressure amplitude, in addition based on one or more of the perspectives pressure change rate, heat loss, exhaust temperature, exhaust work in the combustion chamber, or nitrogen oxides generated during combustion as additional criteria, such determination can be performed according to any of the parallels given below. patent applications. Specifically, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLING AN COMBUSTION ENGINE I" (Swedish patent application, application number: 1350506-0) shows a procedure for regulating subsequent combustion based on an estimated maximum pressure change rate.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR REGULATING AN COMBUSTION ENGINE II" (Swedish patent application, 28 537 30 application number: 1350507-8) shows a procedure for regulating a subsequent part of combustion during a first combustion cycle during said first combustion cycle. a temperature resulting from said subsequent combustion.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLLING 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" discloses a method 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 from said combustion.

Furthermore, the parallel application "PROCEDURE AND SYSTEM FOR CONTROLING AN COMBUSTION ENGINE VI" shows a method 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 combustion during combustion. part of the said first combustion cycle.

According to the present invention, the combustion during adaptive combustion is thus adapted if necessary based on deviations from the predicted combustion, and according to one embodiment, an evaluation of the combustion is performed as soon as an injection has been performed as long as further injections are to be performed. According to the method 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 fuel injection is started in the manner described above, thus also the first injection is performed according to the above procedure.

The regulation has hitherto been described in a manner 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 can be affected by protruding changes in the injection schedule even in cases where a number of 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. 537 30 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. the injected amount of fuel can be redistributed between subsequent injections and / or the injection time can 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 a combustion cycle, the more parameters can be changed, while tired work should be maintained. With a large number of injections, therefore, the regulation can become relatively complex, since a large number of parameters can be varied and thus behavior would 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 also others as above, there may be several essentially equivalent injection strategies, which result in essentially the same maximum pressure amplitude, or which meet set wish lists / requirements for the pressure amplitude. This introduces an undesirable complexity in the calculations. According to one embodiment, a control is applied where the nearest injection / injection is considered as a separate injection at the time, and subsequent industry injections as a single additional "virtual" injection, whereby fuel can be distributed between these "two" injections in one way. which means 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 inspi as above, the injection 502 corresponds to insp2 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 amount 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 then with the injection 503 as a separate injection, see Fig. 5B, and the injection 504, 505 together form a virtual injection when distributed as above.

In Fig. 5A, the virtual injection 506 consists of 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 32 537 30 injections is intended to be performed during the combustion cycle, the process being repeated until all the injections have been performed. 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 drop 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 (lowest) level realistically achievable 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 normal pressure, as is customary, but can also be arranged to be controlled against a expected maximum pressure, such as e.g. curve 603 in Fig. 6, each injection being 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-dissolved pressure sensor. Curve 601 represents the estimated, i.e. expected, the development of the pressure in the combustion chamber based on predicted injection profile. Dashed injections 605, 606, 607 represent the predicted control signal, i.e. the expected injection profile 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, in order 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 for a combustion cycle is performed, 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 instead, such as e.g. high-resolution ion current sensors, knock sensors or strain gauges, whereby the pressure in the combustion chamber can be modeled by using sensor signals from such sensors. It is also 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 only regulating the amount of fuel supplied, the pressure during combustion can be arranged to be regulated with the aid of e.g. exhaust valves, whereby injection can be performed 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 the appropriate type of regulator, or e.g. with the help of state models and state feedback (eg 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 has been exemplified above in connection with vehicles. However, the invention is also applicable to arbitrary vehicles / 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 in no way limited to the above-described embodiments of the method of the invention, but relates to and includes all embodiments of the invention. attached the scope of protection of the independent requirements. 36

Claims (37)

A method of controlling an internal combustion engine (101), wherein said internal combustion engine (101) comprises 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 part of a first combustion cycle, determine at least one first parameter value regarding a quantity at combustion in said combustion chamber (201), 2. based on said first parameter value, estimate a representation of a during said first combustion cycle and in said combustion chamber ( 201) resulting pressure amplitude, and 3. based on said estimated pressure amplitude, regulating subsequent combustion during a subsequent part of said first combustion cycle following part of said first combustion cycle. The method of claim 1, wherein said estimated resulting pressure amplitude is an estimation of a resulting pressure amplitude in said combustion chamber during said subsequent part of said first combustion cycle (201). A method according to any one of claims 1-2, 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 37 537 for controlling said subsequent combustion, said control parameter constituting a control parameter where a expected estimated maximum pressure amplitude is less than a first pressure amplitude when controlling according to said control parameter. A method according to any preceding claim, further comprising determining at least one control parameter for controlling said subsequent combustion based on said resulting pressure amplitude, said control parameter being determined as a control parameter where a expected estimated maximum pressure change rate is less than a first pressure change rate control. . A method according to any one of the preceding claims, further comprising: 1. determining a resultant work requested in said combustion, and 2. determining at least one control parameter for controlling said subsequent combustion based on said resulting pressure amplitude, said control parameter constituting a control parameter there an estimated resultant work in said combustion corresponds to At least half of the said work required. A method according to claim 6, 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 6 or 7, wherein said work desired in said combustion is determined based on a request for work performed by said combustion engine. 38 537 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 using an estimation of a heat release during said combustion. A method according to claim 10, wherein said pressure amplitude is estimated by estimating a pressure pair resulting from the combustion. The method of claim 10 or 11, 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 preceding claim, further comprising controlling combustion during said subsequent portion of said first combustion cycle by controlling the supply of fuel to said combustion chamber (201). A method according to any one of the preceding claims, further comprising: - estimating an expected maximum pressure amplitude for at least two control alternatives for said subsequent combustion by utilizing said first parameter value, and - selecting a control alternative from said plurality of control alternatives for controlling combustion under 39 537. said subsequent combustion based on said expected maximum pressure amplitude. The method of claim 15, further comprising: 1. determining whether any of said control alternatives constitutes a control alternative where the estimated maximum pressure amplitude when controlling 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 15 or 16, 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 15-17, wherein said control alternative consists of alternatives for supplying fuel during said subsequent part of said combustion cycle. A method according to any one of claims 15-18, 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 15-19, wherein At least one fuel injection is performed during said subsequent part of said combustion cycle, wherein at said control injected fuel quantity and / or injection length and / or injection pressure and / or time between injections is regulated for said fuel injection. 537 A method according to any one of claims 15-20, 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 Atmin at least two injections of fuel. A method according to any one of claims 15-21, 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, the remaining single fuel injections are treated as a single fuel injection. injection. A method according to any one of claims 15-22, wherein control of the combustion during said subsequent part of said first combustion cycle is performed at least in part by regulating the fuel injected into said combustion chamber (201) during an ongoing fuel injection. A method according to any one of claims 15-23, further comprising, when regulating the fuel injected into said combustion chamber (201), changing a distribution of fuel quantities between at least two fuel injections. A method according to any one of claims 15-24, further comprising applying a predetermined injection of fuel at the beginning of the combustion cycle, wherein control is performed after a first injection at least has been started, but before fuel injection during said first combustion cycle has ended. 41 537 A method according to any preceding claim, further comprising performing a first fuel injection to said combustion chamber (201) during said first part of a first combustion cycle, and at least a second fuel injection during said subsequent part of said combustion cycle, wherein control parameters for said second industry combustion determined based on said estimated resulting pressure amplitude after said first fuel injection has been at least partially performed. A method according to any preceding claim, further comprising: 1. determining whether the pressure during said combustion during said combustion cycle has reached maximum pressure during said combustion cycle, and 2. interrupting said process when maximum pressure has been reached. A method according to any one of the preceding claims, further comprising, when a pressure amplitude is estimated for said combustion: 1. interrupt estimating when estimation has been performed up to a point where a maximum pressure amplitude during combustion is expected. A method according to any preceding claim, further comprising controlling combustion during said subsequent portion of said first combustion cycle by controlling 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. 42 537 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, states that said computer performs the method according to any of claims 1-32. A computer program product comprising a computer readable medium and a computer program according to claim 33, 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: 1. means for determining during a first part of a first combustion cycle At least one first parameter value regarding a quantity in combustion in said combustion chamber (201), 2. means (115) for based on said first parameter was to estimate a representation of a pressure amplitude resulting in said first combustion cycle and in said combustion chamber (201), and means (115) for regulating, based on said estimated 43 537 pressure amplitude, subsequent combustion during a first said part of said first combustion cycle subsequent part of said first combustion cycle. A system according to claim 35, characterized in that said internal combustion engine consists of nAgon from the group: vehicle engine, marine engine, industrial engine. Vehicle (100), characterized in that it comprises a system according to claim 35. 44