WO2014175818A1

WO2014175818A1 - Method and system for control of an internal combustion engine

Info

Publication number: WO2014175818A1
Application number: PCT/SE2014/050492
Authority: WO
Inventors: Ola Stenlåås; Kenan MURIC
Original assignee: Scania Cv Ab
Priority date: 2013-04-25
Filing date: 2014-04-24
Publication date: 2014-10-30
Also published as: SE537190C2; SE1350509A1; DE112014001773T5; BR112015024990A2; DE112014001773B4

Abstract

The present invention pertains to a method for the control of a combustion engine (101), wherein said combustion engine (101) comprises at least one combustion chamber (201) and elements (202) for the supply of fuel to said combustion chamber (201), wherein combustion in said combustion chamber (201) occurs in combustion cycles. The method comprises: - during a first part of a first combustion cycle, determining a first parameter value representing a physical quantity for combustion in said combustion chamber (201) with the help of a first sensor element, and - based on said first parameter value, controlling the combustion during a subsequent part of said first, combustion cycle, wherein during said control of the combustion in said subsequent part of said first combustion cycle, the combustion is controlled with respect to a work achieved during said combustion. The invention also relates to a system and a vehicle.

Description

METHOD AND SYSTEM FOR CONTROL OF AN INTERNAL COMBUSTION ENGINE Field of the invention

The present invention pertains to combustion engines, and in particular to a method for the control of a 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 background description below constitutes a background description for the invention, and thus need not necessarily constitute prior art tech ology.

With respect to vehicles in general, there are a number of different driveline configurations. For example, the gearbox may consist of a manual speed gearbox, or an automatic gearbox. With respect to heavy goods vehicles , it is often desirable that these should be able to be driven as

comfortably as possible for the driver, which usually means that the gearbox speed changes should be carried out

automatically with the help of the vehicle's control system. Automatic transmission has thus become increasingly common in heavy goods vehicles.

With respect to automatic gearboxes of the type often existing in passenger cars, the efficiency is often too low for the use of this type of gearbox to be justified, other than for use in e.g. city buses and distribution vehicles in cities, where frequent starts and stops are commo . Also, in relation to this type of vehicle, it is becoming increasingly common for drivelines of the type specified below to be used.

Automatic transmission in heavy goods vehicles often consists of a shifting of "manual" gearboxes, controlled by a control system, i.e. gearboxes consisting of one gear set. per gear, where the gear ratio is distributed over suitable steps, e.g. because these are substantially cheaper to produce, but also because of a higher efficiency compared to conventional automatic gearboxes. In such gearboxes, a clutch, which may consist of a clutch automatically controlled by the vehicle's control system, is used in order to connect the vehicle's engine with the gearbox. This clutch/gearbox may also be of e.g. a double clutch type. In principle, the clutch in such vehicles need only be used when the vehicle is started from a standstill, since other- shifting may be carried out by the vehicle's control system without opening the clutch. In cases where the clutch consists of a clutch automatically controlled by the vehicle's control system, however, the clutch is often used to open/close the driveline also when shifting. Regardless of how the shifting is carried out, it is desirable for shifting to be carried out in a manner which is both perceived as comfortable by the vehicle's driver, while at the same time the shifting is also carried out in a manner which is gentle on the components of the drive1ine .

Summary of the invention

One objective of the present invention is to provide a method to control a combustion engine. This objective is achieved with a method according to claim 1.

The present invention pertains to a method for the control of a combustion engine, where said combustion engine comprises at least one combustion chamber and elements for the supply of fuel to said combustion chamber, the combustion in aid

combustion chamber occurring in combustion cycles.

During a first part of a first combustion cycle, a first parameter ^'value, representi g- a physical quantity for combustion in said combustion chamber, is determined with the help of a first sensor element, , and

- based on said first parameter value, the combustion is controlled during a subsequent part of said first combustion cycle where, during said control of the combustion in said subsequent part of said first combustion cycle, the combustion is controlled with respect to the work achieved during said combustion. The control with respect to a work achieved during combustion may e.g. be carried out by controlling the combustion toward a first average pressure during the

combustion cycle, such as an average pressure corresponding- to a desired emitted torque.

As mentioned above, in heavy goods vehicles gearboxes of the type which are usually used in manually shifted vehicles are often used, so that shifting is carried out automatically by the vehicle's control system. When shifting from one gear ratio to another, the driveline is broken in order to be closed again after the new gear has been engaged.

Before the driveline is closed again, however, the combustion engine's engine speed must be synchronised with the expected engine speed for the input shaft of the gearbox, with the new gear engaged, in order to avoid undesired tugs/oscillations when shifting. This change, synchronisation, of the combustion engine speed may be carried out in different manners, which is also described in prior art.

In addition to this synchronisation of the combustion engine ' s engine speed with other speeds of the driveline before closing of the driveline, the combustion engine's emitted torque on the output shaft should, at least when shifting with a closed clutch, be controlled so that the gearbox has "zero torque", i.e. the torque emitted by the combustion engine is controlled to a suitable level in order to reduce and preferably eliminate the torque transmitted between the combustion engine and the driving wheel engagement point, so that the engaging and disengaging of a gear, respectively, may be carried out without undesired tugs due to the driveline being- broken/closed during an ongoing power transmission. At such shifting, it is thus desirable that the torque emitted by the combustion engine may be controlled very accurately in order to eliminate, to the extent possible, such power transmission.

According to the present invention, a method is provided wherein a first parameter value relating to a physical

quantity during co bust ion , e . g . a representation of a

pressure prevailing in the combustion chamber, is determined for at least one point in time after the combustion has been started during a combustion cycle, but before the combustion cycle has been completed; and based on said first parameter value, the combustion is controlled during a subsequent, part of said first combustion cycle with respect to the work achieved during said combustion cycle. As explained below, parameter values may be determined several times during an ongoing combustion cycle, in order thus to determine new control parameters for e.g. the combustion at several

occasions during an ongoing combustion cycle.

Thus, according to the invention, a representation of the work resulting during said subsequent part of said first, combustion cycle, after said first part of said first combustion cycle, may be estimated based on said first parameter value, so that the combustion during said subsequent part of said first combustion cycle may be controlled based on said estimation. Thus an expected work to be done during combustion, during the future part of the combustion cycle, may be predicted through estimation, where the determination of said first parameter value allows for a good estimation, since estimation is carried out based on actually prevailing conditio s i the combustion chamber after the combustion cycle has been

started, since said first parameter value may be determined when a part of said first combustion cycle has lapsed.

According to one embodiment, said first, parameter value may be determined when the combustion of fuel has been started during said first combustion cycle, so that a very good estimation of the expec ed work to be done may be carried out, since the estimation may be carried out. based on an ongoing combustion of fuel. Said first parameter value thus constitutes a

representation of an actually prevailing condition for said physical quantity for a point in time/crank angle position when said first, combustion cycle has been initiated and, according to one embodiment, for a point in time/crank angle position when the combustion of fuel has been initiated.

By estimating a work to be done for the future part, of the combustion cycle, the work for the entire combustion cycle may thus be estimated, where work achieved up to the point in time at which said first parameter value is determined may e.g. be estimated based on actually determined parameter values with the use of said first sensor elements. According to the invention, the combustion is thus controlled during an ongoing combustion cycle, so that the combustion is controlled based on at least one parameter value representing a physical quantity during the combustion, where this physical quantity is directly impacted by the hitherto completed part of the combustion. Thus, in e.g. a situation where a certain torque emitted by the combustion engine is desirable, 3uch as a torque emitted on the combustion engine's output shaft, a hitherto during the combustion cycle actually obtained work may be evaluated and compared with a hitherto expected

obtained work. Further, a condition actually prevailing- during the combustion may be compared with a corresponding expected condition during the combustion, in order to determine whether the combustion is progressing as expected. The combustion parameters may then be controlled as needed, with the

objective to control the combustion with the objective of controlling the combustion toward a desired work to be

achieved during the combustion cycle.

The desired work to be achieved during the combustion cycle may e.g. be expressed as a desired torque, such as a desired average torque during the combustion cycle.

The torque emitted by the combustion engine has a direct connection with the pressure in the combustion chamber, so that the torque may also be represented by the pressure in the combustion chamber. This also means that the desired average torque emitted during a combustion cycle may be obtained by controlling the combustion toward a corresponding average pressure, so that the combustion process may thus be

controlled toward a desired average pressure resulting during the combustion cycle. Thus, said physical quantity may consist of the pressure prevailing in the combustion chamber, so that a representation of this pressure, which e.g. may be obtained directly with the help of a pressure sensor arranged in the combustion chamber, or via another type of sensor for the measurement of another physical quantity, with the help of which a representation of a corresponding pressure may be obtained .

Thus, e.g. an average pressure up to e.g. the point in time at which said, first parameter value is determined, may be

compared with an expected average pressure up to this point in time, so that subsequent combustion may be controlled based on said comparison. The combustion may also be arranged to be controlled e.g. based on a difference between a determined value and an expected value at said point in time. The present invention thus provides a method, which entails that the work done during combustion may be controlled very accurately, and thus the torque emitted on the combustion engine's output shaft may also be controlled very accurately. At e.g. a. request for a certain work (emitted torque) done by the combustion engine on the output shaft , this may be

converted to a combustion chamber work, where internal losses are taken into consideration, etc., which is also explained in the detailed, description below.

The method according to the invention may also e.g. be used in e.g. situations where undesired tugs/oscillations have

nevertheless arisen in the driveline, wherein a very quick control of the combustion may be carried out with the

objective of counteracting oscillations by controlling the torque emitted on the combustion engine's output shaft based on prevailing oscillations in the dr.ivel.ine, wherein reference values for the control may be obtained based on e.g. signals from engine speed sensors.

The regulation of the combustion may be arranged to be carried out individually for each cylinder, and it is also possible to control a combustion during a subsequent combustion cycle, based on information from one or several previous combustion processes .

The method according to the present invention may e.g. be implemented with the help of one or several FPGA (Field- Programmable Gate Array) circuits, and/or one or several ASIC (application-specific integrated circuit) circuits, or other types of circuits which may handle the desired calculation speed .

Further characteristics of the present invention and

advantages thereof will be described in the detailed description of example embodiments set out below and in the enclosed drawings.

Fig. 1A shows schematically a vehicle in which the present invention may be used.

Fig. IB shows a control device in the control system for the vehicle shown in Fig. 1A.

Fig, 2 shows the combustion engine in the vehicle shown in

Fig. 1A in more detail.

Fig. 3 shows an example embodiment according to the present i vention .

Fig. 4 shows an example of an estimated pressure track for a combustion, and an actual pressure track up to a first crank angle position.

Fig. 5A-B show an example of regulation in situations with more than three injections.

Fig. 6 shows an example of MPC .

Detailed description of embodiments

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

The combustion engi e 101 is co trolled by the engi e's control system via a control device 115. Likewise, the clutch 106, which may consist of e.g. an automatically controlled clutch, as well as the gearbox 103 are controlled by the vehicle's control system with the help of one or more

applicable control devices (not. shown) . Naturally, the vehicle's driveline may also be of another type, such as a type with a conventional automatic gearbox, or a type with a manual gearbox, etc.

An output shaft 107 from, the gearbox 103 operates the driving wheels 113, 114 in a customary manner via the end gear and driving shafts 104, 105. Fig. 1A shows only one shaft with driving wheels 113, 114, but in a customary manner the vehicle may comprise more than one shaft equipped with driving wheels, or one or more extra shafts, such as one or more support shafts . The vehicle 100 also comprises an exhaust system with an af er-treatment system 200 for customary treatment

(purification) of exhaust, emissio s resulting from combustion in the combustion chamber (e.g. cylinders} of the combustion engine 101.

Further, combustion engines in vehicles of the type shown in Fig. 1A are often equipped with controllable injectors in order to supply the desired amount of fuel at the desired point in time in the combustion cycle, such as at a specific piston position (crank angle degree} in the case of a piston engine, to the combustion engine ' s combustion chamber.

In Fig. 2 shows schematically an example of a fuel injection syste for the combustion engine 101 e em lif.led .in Fig. 1A. The fuel injection system consists of a so-called Common Rail system, but the invention is equally applicable in other types of i j ection sys te s. Fig. 2 shows on1y one

cylinder/combustion chamber 201 with a piston 203 active in the cylinder, but the combustion engine 101 consists, in the present example, of a six-cylinder combustion engine, and may generally consist of an engine with any number of

cylinders/combustion chambers, e.g. any number of

cylinders/combustion chambers in the range 1-20 or even more. The combustion engine also comprises at least one respective injector 202 for each combustion chamber (cylinder) 201. Each respective injector is thus used for injection (supply) of fuel in 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 injectors, which, based on received control signals, e.g. from the control device 115, control the opening/closing- of the

injectors 202. The control signals for the control of the actuators'

opening/closing of the injectors 202 may be generated by some applicable control device, such as, in this example, by the engine control device 115. The engine control device 115 thus determines the amount of fuel which actually is to be injected at any given time, e.g. based on prevailing operating

conditions in the vehicle 100.

The injection system shown in Fig. 2 thus consists of a so- called Common Rail system, which means that all injectors (and therefore all combustion chambers) are supplied with fuel from a common fuel conduit 204 (Common Rail) , which, with the use of a fuel pump 205, is filled with fuel from a fuel tank (not shown) at the same time as the fuel in the conduit 204, also with the help of the fuel pump 205, is pressurised to a certain pressure. The highly pressurised fuel in the common conduit 204 is then injected into the combustion engine's 101 combustion chamber 201 when the respective injector 202 is opened. Several openings/closings of a specific injector may be carried out during one and the same combustion cycle, whereby SG νθ . cl J. injections may thus be carried out during the combustion of one combustion cycle. Further, each combustion chamber is equipped with a respective pressure sensor 206, for sending of signals regarding a prevailing pressure in the combustion chamber to e.g. the control device 115. The

pressure sensor may e.g. be piezo-based and should be fast enough to be able to send crank angle resolved pressure signals, e.g. at every crank angle degree or more frequently.

With the help of a system of the type shown in Fig. 2, the combustion during a combustion cycle in a combustion chamber may to a large exte t, be co trolled, e.g. with the use of multiple injections, where the times and/or duration of the injections may be controlled, and where data from e.g. the pressure sensors 206 may be taken into consideration in connection with this control. According to the invention, e.g. injection times and/or duration for the respective injection and/or injected fuel amount is adapted during an ongoing combustion, based on data from the ongoing combustion, with the objective to control the combustion ith respect to work done during the combustion cycle, which may e.g. be carried out by controlling the pressure changes arising in the

combustion chamber during- combustion, so that regulation may e.g. be controlled toward a desired average pressure during- a combustion cycle, with the consequence that a very accurate control of the combustion engine's emitted torque may be obtained when e.g. shifting.

In Fig. 3 shows an example method 300 , according to the present invention, where the method according to the present example is arranged to be carried out by the engine control device 115 shown in figs. 1A-B,

In general, control systems in modern vehicles consist of a commu.nica.tion bus system consisting of one or more

communications buses to connect a number of electronic control devices (ECUs) , such as the control device, or controller, 115, and various components arranged on the vehicle. According to prior art, such a control system may comprise a large number of control devices, and the responsibility for a specific function may be distributed among more than one control device .

For the sake of simplicity, figs. 1A--B show only the control device 115, in which the present invention is implemented in the embodiment shown. The invention may, however, also be implemented in a control device dedicated to the present invention, or wholly or partly in one or several other control devices already existing in the vehicle. Considering the speed at which calculations according to the present invention are carried out, the invention may be arranged to be implemented in a control device which is especially adapted for real time calculations of the type described below. The implementation of the present invention has showed that e.g. ASIC and FPGA solutions are suitable for and cope well with calculations according to the present invention.

The function of the control device 115 (or the control device (s) at which the present invention is implemented} according to the present invention may, apart, from depending on sensor signals from the pressure sensor 202, e.g. depend on signals from other control devices or sensors. Generally, control devices of the type displayed are normally arranged to receive sensor signals from different parts of the vehicle, as well as from different control devices arranged on the

vehicle .

Control is often controlled by programmed instructions. These programmed instructions typically consist of a computer- program, which, when it is executed in a computer or control device, causes the computer/control device to carry out the desired control action, as a method step in the process according to the present invention. The computer program usually consists of a computer program product, where the computer program product comprises an applicable storage medium 121 (see Fig. IB), with the computer program stored on said storage medium 121. Said digital storage medium 121 may e.g. consist of any from the following group : ROM (Read-Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable PROM) , Flash, EEPROM (Electrically Erasable PROM) , a hard disk unit, etc. , and may be set up in or in combination with the control device, where the computer program is executed by the control device. By changing the computer program's instructions, the vehicle ' s behaviour may thus be adjusted in a specific situation.

An example control device (control device 115} is shown schematically in Fig. IB, and the control device in turn may comprise a calculation unit 120, which may consist of e.g. a suitable type of processor or microcomputer, e.g. a circuit for digital signal processing (Digital Signal Processor, DSP) , one or several FPGA (Field-Programmable Gate Array) circuits or one or several circuits with a predetermined specific function (Application Specific Integrated Circuit, ASIC) . The calculation unit 120 is connected to a memory unit 121, which provides the calculation unit 120 with e.g. the stored program code and/or the stored data which the calculation unit 120 needs in order to be able to carry out calculations. The calculation unit 120 is also set up to store interim or final results of calculations in the memory unit 121.

Further, the control device is equipped with devices 122, 123, 124, 125 for receipt and sending of input and output signals . These input and output signals may contain waveforms, pulses, or other attributes, which may be detected as information for processing of the calculation unit 120 by the devices 122, 125 for the receipt, of input signals . . The devices 123, 124 for sending output signals 3 Τ - 3rranged to convert the calculation result from the calculation unit 120 into output signals for transfer to other parts of the vehicle's control system and/or the component ( s } for which the signals are intended. Each one of the con ections to the devices for receipt and sending of input and output signals may consist of one or several of the following; a cable, a data bus, such as a CAN (Controller Area Network) bus, a MOST (Media Oriented Systems Transport) bus, or any other bus configuration; or of a wireless connection.

Reverting to the method 300 shown in Fig. 3, the method begins at step 301, where it is determined whether control of the combustion process should be ca ried out. The control

according to the invention may e.g. be arranged to be carried out continuously as soon as the combustion engine 101 is sta rted. A11e rn at ive1y , cont ro1 may be a r ranged to be c a r ried out only in certain situations, e.g. at. opening/c.1osing of the driveline at/during shifting, or to counteract the occurrence of or already present oscillations in the driveline, or at other suitable situations where a very accurate control of the torque emitted by the combustion engine is desirable.

The method accordinq to the present invention thus consists of a method for the control of the combustion engine 101, while the combustion takes place in said combustion chamber 201 in combustion cycles. According to prior art, the term combustion cycle is defined as the steps comprised in a combustion in a combustion engi e, e.g. a two-stroke engine's two strokes and a. four-stroke engine's four strokes. The term also includes cycles where no fuel is actually injected, but where the combustion engine is still operated with a certain engine speed, such as with the vehicle's driving wheels via the driveline in e.g. dragging. That is to say, even if no

injection of fuel is carried out, a combustion cycle is still completed for e.g. every two revolutions (for four-stroke engines) , or e.g. every revolution (two-stroke engines) , which the combustion engine's output shaft rotates. The same applies to other types of combustion engines.

In step 302 , it is determined whether a combustion cycle has been or will be started, and where this is the case, the method continues to step 303 while a parameter i representing an injection number is set equal to one.

In step 303, a work requested by the combustion engine du ing the combustion cycle is determined. For example, the requested work may consist of a reference value for the torque in order to facilitate e.g. shifting, where the reference value has been calculated/determined by e.g. the function that controls shifting. The corresponding pressure reference value may advantageously be tabulated in the control system's memory in order to quickly be retrieved during control according to the present invention .

Generally, the supply of the amount of fuel, both with respect to quantity and manner of supply, i.e. the one or several fuel injections that, are to be carried out during the combustion cycle, is normally defined in advance, e.g. depending on the work (torque) which the combustion engine must carry out during the combustion cycle, since no change of the determined injection schedule is carried out. during an ongoing combustion cycle according to prior art. Predetermined injection

schedules may e.g. exist in tables in the vehicle's control system for a large number of operating modes, such as

different engine speeds, different requested work, different combustion air pressures, etc., where tabulated data may e.g. be prepared by way of applicable tests/measurements during e.g. the development of the combustion engine and/or vehicle, so that the applicable injection schedule may be selected based on prevailing conditions, and where the injection schedule may be selected e.g. based on a request for a certain emitted torque, e.g. from a function that controls e.g.

shifting. These injection schedules may consist, of the number of injections and respective characteristics in the form of e.g. timing (crank angle position) of the start of the

injection, the duration of the injection, the injection pressure, etc., and thus may be stored for a large number of operating modes in the vehicle's control system.

Based on the requested work determined in step 303, in step 304 an injection schedule is then determined which is expected to result in a desired work achieved, such as an average torque, during the combustion cycle's combustion, where the injection schedule is selected, being based on prevailing conditions, e.g. engine speed, combustion air pressure, in addition to being based on a requested work.

The torque emitted during the combustion engine's combustion generally constitutes a mean value of the work the combustion engine is developing, and this work, is usually called MEP mean effective pressure.

Generally, the following connection between torque M and power P app1 ies :

P

M = (1)

, where N constitutes the combustion engine's engine speed, which is available in the vehicle's control system.

Further, the following connection between mean effective pressure MEP and power applies: Pit^■,c

MEP = (2)

, where n_c constitutes the number of revolutions per combustio cycle_., i.e. 2 for four-stroke engines and 1 for two-stroke engines. V_d constitutes the combustion chamber's volume.

With the use of equation (1) to describe the power P in equation (2), thus the connection between torque M and mean effective pressure, for a four-stroke engine, may be written as :

4πΜ

MEP --

V, (3)

d

Thus a mean effective pressure corresponding to a desired torque in the combustion engine's combustion chamber may be determined with the use of equation 3. Since V_d is known, MEP may e.g. be tabulated in relation to torque in the vehicle's control system in order to facilitate quick access to a reference value, against which the pressure in the combustion chamber should be controlled,

A combustion engine's work, e.g. expressed as mean pressure, may, however, be defined in different ways. For example, a work will be achieved during the combustion, but this entire work will not, because of e.g. losses, be made available on the combustion engine's output shaft.

The work achieved in the combustion chamber is generally called !MEP (indicated mean effective pressure) , which also represents the resulting work of the combustion in the combustion chamber.

Since a combustion engine generally comprises losses, such as pump losses at gas shifting work and friction losses, IMEP it thus does not directly represent the torque emitted on the combustion engine's output shaft. At e.g. a torque request from another function occurring at the engine, e.g. a function for the control of shifting, as set out above, normally a work done on an output shaft, of the combustion engine is requested, however, which due to the combustion engine's losses entails that the mean effective pressure required in order to obtain a desired work on the output shaft does not correspond exactly to equation (3) .

The work done on the combustion engine's output shaft is generally called BMEP (brake mean effective pressure) , which consists of IMEP , but is compensated for the combustion engine's losses.

These losses may be calculated specifically, but usually the combustion engine's efficiency is well tabulated, so that BMEP may be determined as :

BMEP - μ_ιηΰ€!ιΙΜΕΡ_η (4)

Where constitutes the combustion engine's efficiency. μ_πιβ€ΐι may be available tabulated for a large number of operating conditions, and with very good accuracy, so that a quick conversion between BMEP and IMEP , respectively, may be carried out when needed.

Thus the mean, effective pressure required, in the combustion engine's combustion chamber IMEP in order for the desired torque on. the combustion engine's output, shaft to be obtained may be written as:

1 4πΜ

IMEP 5 Thus, on request for a torque on the combustion engine ' s output shaft, a corresponding required mean effective pressure for the combustion may easily and quickly be determined, and the present invention thus pertains to a method to control the combustion in such a manner that the combustion is controlled toward this mean effective pressure !MEP through the use of control of the combustion for a combustion cycle, during an ongoing combustion cycle. The control, according to the invention, may be arranged to be carried out continuously for consecutive combustion cycles in order to ensure a very- accurate emission of requested torque during e.g. a shifting operation .

The mean effective pressure IMEPin the combustion chamber during a combustion cycle may also be written as;

, where CAD stands for camshaft degrees, i.e. an integration is carried out over an entire combustion cycle.

In step 304 thus, as set out above, an injection schedule is determined which is expected to result in a desired mean effective pressure !MEP , and thus the desired emitted torque during the combustion cycle's combustion, and according to this embodiment, a pre-defined injection schedule at the start of the combustion cycle is thus applied, where control action, according to the invention, is carried out only after the fuel injection has been started during a combustion cycle, such as only after at least one injection has been completed during the combustion cycle, or after one injection has at least been started , Fuel injection is thus normally carried out according to a prede ermined schedule, where several injections may be arranged to be carried out during one and the same combustion cycle. This entails that the injections may be relatively short. For example, there are injection systems with 5-10 fuel injections/combustion, but the number of fuel injections may also be significantly greater, e.g. in the range of 100 fuel injections during one combustion cycle. The number of possible injections is controlled generally by the speed of the

elements with which injection is carried out, i.e. in the case of a Common Rail system how fast the injectors may be opened and closed.

According to the present example, at least three fuel

injections inspi are carried out during one and the same combustion cycle but, as mentioned and as set. out. below, a greater number of injections may be arranged to be carried out, as well as only one.

The injection schedule is thus in the present example

determined in advance, with the objective to obtain a certain work achieved (mean effective pressure) . A first injection inspi is carried out, and in step 305 it. is determined whether said first injection inspi has been carried out. and, if so, the method continues to step 306, where it is determined whether all the injections i have been carried out. Since this is not yet the case in the present, example, the method continues to step 307 while i is incremented by one for the next injection. Further, with the continuous use of the pressure sensor 206, such as with applicable intervals, e.g. every 0.1-10 crank angle degrees, the prevailing- pressure in the combustion chamber is determined. The combustion process may generally be described with the pressure change in the combustion chamber which the combustion gives rise to. The pressure change during a combustion cycle may be represented by a pressure track, i.e. a representation of how the pressure in the combustion chamber varies during the combustion. As long as the combustion progresses as expected, the pressure in the combustion chamber will be equal to that initially estimated, but as soon as the pressure deviates from the estimated pressure, the work which has been achieved will also deviate from that assumed in advance.

If the combustion after the first injection inspi has thus continued just as expected, the conditions in the combustion chamber will correspond to the conditions intended for the injection, and likewise the hitherto resulting mean pressure will correspond to the expected pressure up to this point. As soon as the conditions deviate from the intended conditions, however, the hitherto resulting mean pressure will deviate from the expected mean pressure, and likewise, the subsequent- part of the combustion will also be impacted, since the conditions prevailing in the combustion chamber e.g. with respect to pressure/temperature, will not correspond to the expected conditions at the next injection.

In practice the actual pressure track during the course of the combustion will also very probably deviate from the pressure track predicted with estimation, due to e.g. deviations from the modelled, combustion, etc. This is illustrated in Fig. 4, where a predicted pressure track 401 for an example injection schedule is shown (very schematically), i.e. the expected pressure track for the combustion chamber when the injection is carried, out according to the selected injection profile. This prediction of the pressure track may e.g. be carried out as described below. In Fig. 4 also displays an actual pressure track 02 up to the crank angle position φ-j , which constitutes the prevailing position after said first combustion has been carried out.

Preferably, the pressure in the combustion chamber is thus determined, substantially continuously during the entire

combustion, e.g. at each crank angle degree, every tenth crank angle degree or with another suitable interval. As may be seen in Fig. 4 , the actual pressure track up to ψι deviates from the estimated pressure track 4 0 1 . This means in turn that, the hitherto prevailing mean pressure up to crank angle position cpi also has deviated from the expected mean pressure.

Since the pressure ρ_φ1 in the combustion chamber after the first injection inspi has been carried out deviates from the corresponding estimated pressure at the crank angle position (pi , the conditions in the combustion chamber at the point in time for the next consecutive injection insp₂ will deviate from the predicted conditions, so that subsequent combustion will also deviate from the predicted combustion, if the previously determined injection schedule were still to be used. The mean effective pressure hitherto also deviates from the predicted, and thus it is not at all certain that the desired mean

effective pressure will be achieved, and thus that the

expected work will be done, during the combustion cycle.

Therefore it also not at all certain that it is the o igi ally determined injection schedule which constitutes the most preferred injection schedule in an effort to achieve the desired mean pressure during the combustion cycle, since the mean effective pressure depends on the pressure track, which in turn depends on how fuel is supplied to the combustion.

In step 30 8 therefore, an injection schedule is determined again, with the objective to control the combustion toward a desired mean pressure during the combustion, and at the determination a mean pressure resulting during the combustion hitherto may be determined, so that an injection schedule may be determined which is expected to result in a desired mean effective pressure. The method steps may then be repeated after each injection in order to continuously control the combustion toward the desired mean effective pressure.

The control may e.g. be carried out according- to the

calculations displayed below, alternatively according to other applicable calculations with a similar objective, and thus be repeated, as set out below, during an ongoing- combustion cycle in order to, where needed, change the injection schedule during an ongoing combustion if the actually prevailing conditions in the combustion chamber deviate from the

predicted conditions, so that the combustion may be corrected in order to achieve a desired work to a greater extent. The pressure in the combustion chamber may be determined

continuously during the combustion with the use of the

pressure sensor 206, in order to determine a hitherto obtained mean p es sure . At the estimation of an expected mean pressure during the remaining combustion, however, an estimation of the pressure change during the combustion is also required. This may be estimated as follows.

The combustion may, as is known to a person skilled in the art, be modelled according to equation (7} : dQ = K_calihrate (Q_fuel - Q) (7)

, where K_caUbrate is used to calibrate the model. K_caUbrate consists of a constant which is usually in the range of 0-1, but may also be arranged to assume other values, and which is determined individually, cylinder by cylinder, or for a certain engine or engine type, and depends in particular on the design of the injector nozzles (spreaders) ,

Q_fuel consists of the energy value for the injected fuel amount,

Q consists of the amount of energy burned. The combustion dQ is thus proportionate to the injected fuel amount, minus the hitherto consumed fuel amount. The combustion dQ may,

alternatively, be modelled with the use of another applicable model, where e.g. regard may be had also to other parameters. For example, the combustion may also constitute a function which depends on a model of turbulence arising when air/fuel is supplied, which may impact the combustion to different extents, depending on the amount of air/fuel supplied.

Regarding the fuel injections, these may e.g. be modelled as a sum of step functions:

The fuel flow measured in supplied mass m at an injection k, i.e. how the fuel enters the combustion chamber during the time window u when the injection is carried out, expressed as the time lapsed during the crank angle degree φ interval when the injector is open, may be modelled for a specific injection k as : dm

f(rn)u (9)

dt where m constitutes the injected fuel amount, and f (rn) e.g. depends on the injection pressure, etc. f (m) may e.g. be measured or estimated in advance. The energy value Q_Lf1v for the fuel, such as diesel or petrol, is generally specified, so that, such a general specification may be used. The energy value may also be specifically

provided by e.g. the fuel manufacturer, or be approximated for e.g. a country or a region. The energy value may also be arranged, to be estimated by the vehicle's control system.. With the energy value, the equation (7} may be resolved and the neat release may be determined as the combustion progresses.

Further, through the use of a predictive heat release

equation, the pressure change in the combustion chamber may be estimated as e.g.:

The pressure change is thus expressed in crank angle degrees φ, which entails an elimination of the combustion engine speed, dependency of the calculations, γ generally constitutes the

C_B C„

heat capacity ratio, i.e. γ^■=—-= ---— , where C„ and/or C_v are generally prepared and tabulated for different molecules, and since the combustion chemistry is known, these tabulated ^'values may be used, together with the combustion chemistry in order to thus calculate each molecule's (e.g. water, nitrogen, oxygen, etc.} impact on e.g. the total C_p value, so that this may be determined for the calculations above with a good accuracy, in advance or during e.g. ongoing- combustion.

Alternatively, C„ and/or C„ may be approximated in a suitable manner .

Integration of equation (10) entails the follo ing result: dQ γ dV

P ^~~ P initial = Pmtiiai άφ

άφ γ— 1 ^' άψ (11)

P initial constitutes an initial pressure which, before the start of the combustion ^! s compression step, may e.g. consist of the ambient pressure for combustion engines without a turbo, or a prevailing combustion air pressure for an engine with a turbo.

When the estimation is carried out at a later point in time during the combustion cycle, such as estimation in step 307 after an injection has been carried out, p initial may constitute the then prevailing pressure, as determined by the pressure sensor 206, i.e. ρ_φι in the present example. V(p , i.e. the combustion chamber's volume as a function of crank angle, may advantageously be tabulated in the control system's memory or dv

be calculated in an applicable manner, whereby also — may be άφ

determined .

Thus the pressure p in the combustion chamber is estimated for the entire combustion, i.e. the expected curve 401 in Fig. 4 may be estimated. Thus, an expected mean pressure for the subsequent part of the combustion cycle may also be estimated with the use of equation (6) above, and also for the entire combustion cycle where the actual mean pressure may be applied to the part of the combustion cycle which has already lapsed.

The expected mean effective pressure for a certain injection schedule may thus be estimated with the use of the above equations. In step 307, several different injection schedules may thus be evaluated according to the above equations, where the respective injection schedules will give rise to a

specific pressure track, and thus a mean effective pressure, which is estimated for the specific injection schedule. Subsequently, an injection schedule for subsequent injections may be selected, which is e.g. expected to result in a mean effective pressure which best corresponds to the desired mean effective pressure , Control of the pressure in the combustion chamber may thus be carried out by controlling the fuel injection, and by carrying out an estimation of the mean effective pressure for a number of different injection schedules with varying injection times/injection durations/number of injections, an injection schedule may thus be determined which, to an applicable or as great an extent, as possible, results in a desired mean

effective pressure.

Thus, in step 307, an injection schedule may be determined, such as one injection schedule among several defined injection schedules, which best fulfils the desired mean effective pressure, where this injection schedule may be determined individually, cylinder by cylinder, based on sensor signals from at least one pressure sensor in the respective combustion chamber . In relation to said injection schedule, there may be e.g.

several injection schedules defined in advance, where

calculations of the type described above may be carried out for each one of these available injection schedules.

Alternatively, the calculations may be carried out for the injection schedules which, for some reason, most probably are deemed to result in a desired mean effective pressure. For example, the injection schedules may be evaluated or rejected with respect to the total amount of fuel which will be

injected according to the schedule, where e.g. a large amount of fuel may e.g. be assumed to result in too high a mean effective pressure, in particular if the hitherto resulting- mean effective pressure is above the expected mean effective pressure, and, in the reverse, at least in certain cases too low a total fuel amount may be expected to result in too low a mean effective pressure . Hitherto, the entire injection schedule for the remaining combustion has been evaluated, but control may also be

arranged, to be carried out only for a future injection after a previous injection, whereby subsequent injections may be managed gradually. The injection schedule selected in step 307 may thus consist of only the next injection.

When the injection schedule has been selected in step 307, the method reverts to step 304 in order to carry out the next injection, which also gives rise to a combustion, and thus a pressure track, which will probably also deviate from the pressure track predicted in advance. This also means that the combustion, also at subsequent injections, will probably be impacted by prevailing conditions in the combustion chamber when the injection is started, and that the hitherto resulting mean effective pressure has again been changed from the expected.

Thus, in step 307, after a subsequent injection has been completed, a new injection strategy for the remaining

injections, alternatively for the subsequent injection, may be calculated with the help of the above equations, and the method then reverts to step 304 in order to carry out

subsequent fuel injections according to the new injection strategy calculated in step 307. Control may thus be arranged to be carried out after each injection i, and when all

injections i have been completed, the method reverts from step 307 to step 301 for the control of a subsequent combustion cycle , In the above calculations, after: each injection, the current pressure determination ρ_φι is used by using the pressure sensor 206 in the way p_initiai described above, in order to again predict the pressure track/mean effective pressures, in order to determine a new injection schedule based on the now prevailing conditions in the combustion chamber, but. now with data obtained further along in the combustion. That is to say, p_<pi following the first combustion and similarly determined ρ_φί for subsequent injections, where thus Pinitiai changes at

calculations during- the combustion cycle, and where the fuel injection is adapted according to prevailing conditions after each injection, with the consequence that the injection schedule may change after each injection.

The present invention thus provides a method which adapts the combustion as the combustion progresses, where the combustion engine's combustion may be controlled very exactly toward a desired torque emitted, where procedures such as shifting- may be carried out with great accuracy, with control during an ongoing combustion cycle and thus in a manner which is gentle both to the driver and the driveline. In addition, the control may be used to counteract oscillations which may arise in the driveline, where the combustion engine may be controlled very exactly, with the objective to counteract undesired effects, e.g. oscillations, through applicable torque control.

According to the present invention, the combustion is thus adapted during ongoing combustion, based on deviations from the predicted combustion and, according- to one embodime t, each time an injection inspi has been completed as long as additional injections are to be carried out. instead of evaluating a number of defined injection schedules in step 307, e.g. a regulator may be used, which, based on e.g. a determined deviation between a desired mean effective pressure and the hitherto obtained mean effective pressure, with quantity and signs, controls subsequent combustion, where e.g. one or several subsequent injections may be adapted according to how the combustion should have occurred and how it actually occurred. For example , the fuel amount for subsequent injections according to the predetermined injection schedule may be increased if the mean effective pressure is lower than expected, or may be reduced i f the mean effective pressure is higher than expected. This may be carried out for each subsequent injection, so that a good control may be achieved. The fuel amount may e.g. be controlled by

increasing/reducing the fuel amount, with a fuel amount obtained by multiplying the previously determined fuel amount for the injection by the difference between hitherto expected mean effective pressure and hitherto actually obtained mean effective pressure with some applicable constant.

According to the above described method, the injection

schedule at the start of the combustion cycle has been

determined based on tabulated values but, according to one embodiment, the injection strategy may, already before the fuel injection starts, be determined in the manner described above, so that also the first injection is thus carried out according to an injection schedule determined as set out above .

Further, the control has hitherto been described in a manner where the characteristics for a subsequent injection are determined based on prevailing conditions in the combustion chamber after the previous injection. The control may, however, also be arranged to be carried out. continuously, where pressure determinations may be carried out with the help of the pressure sensor also during ongoing injection, and where the injection schedule may be calculated and corrected all the way until the next injection is initiated.

Alternatively, even the ongoing injection may be impacted by calculated changes in the injection schedule, also in the cases where several shorter injections are carried out. The injection may also consist of one single, longer injection, where changes to the ongoing injection may be made

continuously, e.g. by way of so-called rate shaping, e.g. by changing the opening area of the injection nozzle and/or the pressure with which the fuel is injected, based on estimations and measured pressure values during the injection. Further, fuel supply during the combustion may comprise two fuel injections , where e.g. on .1y the second. or both inject io s are controlled, e.g. with the help of rate shaping. Rate shaping may also be applied in the event three or more injections are carried out.

In relation to the injection strategies which should be evaluated, these may be devised in different ways. For

example, different distributions between injections may be evaluated, and e.g. an injected fuel amount may be

redistributed between subsequent injections and/or the

injection time may be changed for one or several subsequent injections, where potential limitations with respect to e.g. the minimum permitted duration or fuel amount for a fuel injection is taken into consideration.

Instead of evaluating a number of specific injection

schedules, the method may be arranged to carry out e.g. the above calculations for a number of possible scenarios, where the calculations may be carried out for different injection durations /amounts times for the different injections, with corresponding changes in released energy. The more fuel injections carried out during a combustion cycle, the more parameters may be changed. In the event of a large number of injections, the control may therefore become relatively complex, since a large number of parameters may be varied and. would thus need to be evaluated. For example, a very great number of injections may be arranged to be carried out during one and the same combustion cycle, such as ten, or even hundred or so injections.

In such situations there may be several equivalent injection strategies, which result in substantially the same mean effective pressure. This introduces an unwanted complexity in the calculations.

According to one embodiment, a control action is applied where the injection nearest in time is considered to be a separate injection, and subsequent fuel injections are considered to be one single additional "virtual" injection, so that the heat losses may be optimised between these two injections. This is exemplified in Fig. 5A, where the injection 501 corresponds to inspi, as set out above, the injection 502 corresponds to insp₂, as set out above, and where remaining injections 503-505 are treated as one single virtual injection 506. By proceeding in this manner, the shifting which occurs between insp,? and subsequent injections does not need to be distributed

specifically between the injections 503-505, but the

distribution at this stage is made between the injection 502 and the "virtual" injection 506, respectively..

When the injection 502 has then been completed, the method is repeated, exactly as above, with a new determination of an injection schedule, in order to obtain a desired mean

effective pressure, but with the injection 503 as a separate injection, see Fig. 5B, and the injections 504, 505 jointly constituting one virtual injection as the distribution is made, as set out above.

In Fig. 5A the virtual injection 506 is constituted by three injections, but as is obvious, the virtual injection 506 may comprise, from the beginning, more than three injections, such as tens of injections or hundreds of injections, depending on how many injections that are planned to be carried out during the combustion cycle, so that the method is repeated until all the injections have been completed. It is also possible to use e.g. MPC (Model Predictive Control) in the control according to the invention.

One example of MPC is shown in Fig. 6, where the reference curve 603 corresponds to the expected development for the mean effective pressure during the combustion cycle, i.e. the result of equation (6) with the pressure estimated as set out above. The curve 603 thus represents the mean effective pressure development which is sought during the combustion cycle. The specific appearance of this mean effective pressure development may advantageously be determined in advance, e.g. with applicable calculations and/or measurements for the engine type, where such data may be stored in the control system's memory as a function of e.g. engine speed and load. This entails also that the combustion need not be controlled only toward a mean effective pressure prevailing at each time, but may also be arranged to be controlled toward an expected mean effective pressure development, e.g. the curve 603 in Fig, 6, where each injection may nave as its objective to attain a. hitherto resulting mean effective pressure, which at some given point in time amounts to a corresponding point on the curve 603. The solid curve 602 until the time k represents the actual mean effective pressure which has arisen to date, and which is calculated as set out above with the help of actual data from the crank angle resolved pressure transmitter. The curve 601 represents the predicted development of the mean effective pressure, based on the predicted injection profile, and thus constitutes the expected mean effective pressure development. Dashed i ections 605, 606, 607 represe t the predicted control signal, i.e. the injection profile which is expected to be applied, and 60S, 609 represent already completed in ections .

The predicted injection profile is updated with applicable intervals, e.g. after each completed injection, in order to reach the final value sought and which is given by the

reference curve 603, and where the next injection is

determined based on prevailing conditions in relation to the estimated mean effective pressure development.

Thus, the present invention provides a method which allows for a very good control of a combustion process, and which adapts the combustion during ongoing combustion, in order to obtain a very careful regulation of emitted torque.

According to the above, a work that will be achieved may thus be estimated for several different alternative injection schedules for the remaining injections, so that an injection schedule which results in a requested work may be selected when the subsequent injection is carried out. In cases where several injection schedules/control alternatives fulfil the applicable conditions, other parameters may be used to select which of these are to be used. There may also be other reasons for simultaneously effecting control also on the basis of other parameters. For example, injection schedules may also be partly selected based on one or several of the perspectives pressure amplitude, heat loss, exhaust temperature, pressure change rate, or nitrogen oxides generated during the

combustion as a further criterion, in addition to being selected based on work achieved, where such determination may be carried out according to any of the parallel patent

applications specified below.

Specifically, in the parallel application "METHOD AND SYSTEM FOR CONTROL OF A COMBUSTION ENGINE V" (Swedish patent

application, application number: 1350508-6) a method is shown, which, based on an estimated maximum pressure amplitude, controls subsequent combustion.

Additionally, the parallel application "METHOD AND SYSTEM FOR CONTROL OF A COMBUSTION ENGINE II" (Swedish patent

application, application number: 1350507-8) shows a method to, during a first combustion cycle, control a subsequent part of the combustion during said first combustion cycle, with respect to a temperature resulting in said subsequent

combustion .

Additionally, the parallel application "METHOD AND SYSTEM FOR CONTROL OF A COMBUSTION ENGINE I" (Swedish patent application, application number: 1350506-0) shows a method to control subsequent combustion, based on an estimated maximum pressure change rate.

Further, the parallel application "METHOD AND SYSTEM FOR

CONTROL OF A COMBUSTION ENGINE IV" shows a method to, during a first combustion cycle, control combustion during a subsequent part of said first combustion cycle, with respect to a

representation of a heat loss resulting- during said

combustion . Further, the parallel application "METHOD AND SYSTEM FOR

CONTROL OF A COMBUSTION ENGINE VI" shows a method to, during a first combustion cycle, estimate a first measure of nitrogen oxides resulting from combustion during said first combustion cycle, and. to control the combustion during a subsequent part of said first combustion cycle based on said first measure.

The invention has been exemplified above in a manner where a pressure sensor 206 is used to determine a pressure in the combustion chamber, and with this pressure the eat losses may then be estimated. As an alternative to usi g- pressure

sensors, instead one (or several) other sensors may be used, e.g. high-resolution ion current sensors, knock sensors or strain gauges, where the pressure in the combustion engine may be modelled with the use of sensor signals from such sensors. It is also possible to combine different types of sensors, e.g. in order to obtain a more reliable estimation of the pressure in the combustion chamber, and/or to use other applicable sensors, where the sensor signals are converted into corresponding pressures for use in control, as set out- above .

Further, in the above description, only the fuel injection has been adjusted. Instead of only controlling the amount of fuel supplied, the mean effective pressure during combustion may be arranged to be controlled with the help of e.g. exhaust

'valves, so that injection may be carried out according to a predetermined schedule, but where the exhaust, valves are used to, where needed, e.g. reduce the pressure in the combustion chamber and thus also the mean effective pressure.

Further, control may be carried out with some applicable type of regulator, or e.g. with the help of state models and state feedback (e.g. linear programming, the LQG method or similar). The method according to the invention for the control, of the combustion engine may also be combined with sensor signals from other sensor systems where the resolution of the crank angle level is not available, e.g. another pressure

transmitter, O_x sensors, ¾ sensors, PM sensors, oxygen sensors and/or temperature transmitters, etc., the input signals of which may e.g. be used as input parameters in the estimation of e.g. neat losses, with the use of computer- driven models instead of models of the type described above.

Additionally, the present invention has been exemplified above in relation to vehicles. The invention is, however, also applicable in any vessels/processes where combustion control as per the above is applicable, e.g. watercrafts and aircrafts with combustion processes as per the above.

It should also be noted that the system may be modified according to various embodiments of the method according to the invention (and vice versa) , and that the present invention is in no way limited to the above described embodiments of the method according to the invention, but pertain to and comprise all embodiments in the scope of the enclosed independent claims .

Claims

<Χ.3.

1. Method for the control of a combustion engine (101),

wherein said combustion engine (101) comprises at least one combustion chamber (201) and elements (202) for the supply of fuel to said combustion chamber (201), wherein combustion in said combustion chamber (201) occurs in combustion cycles, wherein the method is rised in that:

- during a first part of a first combustion cycle, with the help of a first sensor element, determine a first parameter value representing a physical quantity for combustion in said combustion chamber (201), and

- based on said first parameter value, control the combustion during a subsequent part of said first combustion cycle, so that during said control the

combustion in said subsequent part of said first

combustion cycle is controlled with respect to a work achieved during combustion.

2. Method according to claim 1, further comprising:

- based on said first parameter value, estimating a representation of a work resulting from combustion during said subsequent part of said first, combustion cycle, after said first part of said first combustion cycle , and

- based on said estimated work, to control the combustion during said subsequent part of said first combustion cycle .

3. Method according- to claim 1 or 2, further comprising- :

- based on said first pa ameter value, estimating a representation of an expected work resulting during said first combustion cycle and

- based on said estimated resulting work, to control the combustion during said subsequent part of said first combustion cycle.

4. Method according to any of the previous claims, also

comprising :

- determining said first parameter value when a part of said first combustion cycle has lapsed.

5. Method according to any of the previous claims, also

comprising :

- determining said first parameter value when combustion of fuel has started during said first combustion cycle.

6. Method according- to any of the previous claims, also

comprising :

- determining a parameter value corresponding to said first parameter value at a number of points in time/crank angle positions during said first combustion cycle, and for the respective determined parameter value, estimating a respective resulting work from combustion expected during said first combustion cycle, and

- controlling combustion during a subsequent part of said first combustion cycle, following determination of the respective parameter value based on the respective estimated work during said first combustion cycle.

7. Method according to claim 6, further comprising:

- determining said parameter value corresponding to said first parameter value at a number of points in time/crank angle positions, after the combustion of fuel has been initiated during said first combustion cycle.

8. Method according to any of claims 1-7, where the work achieved during said combustion is represented by an average pressure during said combustion cycle.

9. Method according to any of clams 1-8, also comprising, based on said first parameter value, determining control parameters for the control of the combustion during said subsequent part of said first combustion cycle.

10. Method according to any of claims 1-9, wherein, during said control with respect to the work achieved during combustion, the combustion is controlled toward a first average pressure corresponding to said work achieved during said combustion cycle.

11. Method according to any of claims 1-10, further

comprising :

- determining an achieved work requested for said

combustion cyc1e , and

- controlling the combustion during said subsequent part of said first combustion cycle toward said requested achieved work,

12. Method according to claim 11, where the ob requested for said combustion is represented by a requested average torque for said combustion cycle.

13. Method according to any of the previous claims, also

comprising :

- estimating a represe tation of a hitherto resulting work during said first combustion cycle, and

- controlling said subsequent part of said combustion cycle based on said representation of said hitherto resulting work during said first combustion cycle

14. Method according- to claim 13, further comprising- :

- controlling the combustion during said subsequent pa t, of said first combustion cycle, based on a comparison between an estimated expected work, and a requested work achieving said combustion cycle. , Method, according to any of the previous claims, also comprising :

- comparing a representation of a resulting average pressure up to the point in time/crank angle position at which said first, parameter value is determined, with a. representation of an expected average pressure up to such point in time/crank angle position, and

controlling subsequent combustion based on said

comparison . , Method according- to any of the previous claims, also comprising, at said determination of control parameters for said subsequent part of said combustion cycle, estimating an expected pressure change during said subsequent part of said, combustion, cycle with the help of said first parameter value. , Method according- to any of the previous claims, also comprising to determine at least one control parameter for the control of the combustion during said subsequent part of said first combustion cycle, where, at the determination of said at least one control parameter, a work expected, to be achieved during combustion in said subsequent, part of said first combustion cycle, is estimated with the use of said first parameter value. , Method, according to any of the previous claims, wherein, during said control, an expected work is estimated during said combustion cycle. , Method according to claim 18, wherein said expected work, is estimated with the use of an estimation of a eat release during said combustion. , Method according to any of the previous claims _f also comprising :

- estimating an expected work for at least two control alternatives for the control of the combustion during said subsequent part of said first combustion cycle, and

- controlling the combustion during said subsequent part of said first combustion cycle, based on said

estimations . , Method according- to any of claims 18-20, wherein, at the estimation of said expected achieved work, a pressure change during said remaining part of said combustion cycle is estimated, with the use of said estimation of a heat release during said combustion. , Method according to one of the previous claims, wherein said first parameter value represents a pressure

prevailing in said combustion chamber (201) during said first co bustion cycle. , Method according- to any of the previous claims, also comprising to control combustion during said subsequent part of said first combustion cycle through control of fuel for supply to said combustion chamber (201) . , Method according to any of the previous claims, also comprising, during said control of said combustion in said subsequent part of said combustion, determining an expected achieved work, during said combustion cycle for several control alternatives, and

- among said number of control alternatives, selecting a control alternative for the control of said subsequent part of said combustion cycle,

25. Method, according to any of the previous claims, also

comprisin :

- durinq said control, evaluating at least a first and a second control alternative, respectively, so that the first or second control alternative, whichever is

expected to result sooner in a requested completed job, is selected.

26. Method according to claim 24 or 25, wherein said control alternative consists of alternatives for the supply of fuel for at least one fuel supply durinq said subsequent pa.rt of sa.id combust. ion cyc1e .

27. Method according to any of claims 23-25, wherein fuel for supply to said combustion chamber (201} is controlled throuqh control of fuel injection with at least one fuel injector (202) .

28. Method according to any of claims 23-27, wherein at least one fuel injection is carried out durinq said subsequent part of said combustion cycle, wherein a fuel amount and/or injection time and/or injection duration is contro11ed for said fue1 injection .

29. Method according to any of claims 23-28, wherein at least two injections of fuel a e carried out. during said subsequent part of said combustion cycle, wherein a remaining part of said combustion is controlled, at least after said first of said at least two injections of fuel.

30. Method according to any of claims 23-29, wherein during control of said combustion, at least three fuel

injections a. e carried out. during said subsequent pa t, of said combustion process, wherein at the determination of control parameters for a first of said at least three fuel injections, the remaining fuel injections are treated as one aggregate injection during said control.

31. Method according to any of claims 23-30, wherein control of combustion during said subsequent part of said first combustion cycle is carried out at least, partly through control of fuel for injection to said combustion chamber (201) , during an ongoing fuel injection.

32. Method according to any of claims 23-31, further- comprising, during the control of fuel for injection to said combustion chamber (201) , changing a distribution of fuel amounts between at least two fuel injections,

33. Method according to any of the previous claims, further comprising carrying out a first injection of fuel to said combustion chamber (201) during said first part of said first combustion cycle, and at least one second fuel injection during said subsequent part of said combustion cycle, wherein the control parameters for said second fuel injection are determined after said first, fuel inj ection .

34. Method according to any of the previous claims, also

comprising to control combustion during said subsequent part of said first combustion cycle through control of one or several valves operating at said combustion chamber (201) .

, Method accordi g- to any of the previous claims, wherei said control is carried out for a number of consecutive combustion cycles. , Method according to any of the previous claims , wherein said first parameter value regarding a physical quantity for combustion in said combustion chamber (201) is determined at least at each crank angle, every tenth of every crank angle or every hundredth of every crank angle . , Method according to any of the previous claims , wherein said first parameter value is determined with the use of one or several from the group: a cylinder pressure transmitter, a knock sensor, a strain gauge, a speed sensor, an ion curre t, sensor, , Method according- to any of the previous claims, also comprising carrying out said control of said combustion at opening/closing of a driveline to which said

combustion engine is selectively connectible. , Method according to any of the previous claims, also comprising, before said determination of said first parameter value :

- based on a requested work, determining- a first fuel injection schedule for said first combustion cycle, wherein said first fuel injection schedule is expected to result in said requested work, , Computer program comprising a program code which, when said program code is executed in a computer, achieves that said computer carries out the method according to any of the claims 1-39. , Computer program product comprising a computer-readable medium and a computer program according to claim 40, wherein said computer program is comprised in said computer-readable medium .

42. System for the control of a combustion engine (101) , wherein said combustion engine (101) comprises at least one combustion chamber (201) and elements (202) for the supply of fuel to said combustion chamber (201) , wherein combustion i said combustion chamber (201) occurs i combustion cycles, characterised in that the system, comprises elements (115) to:

- during a first part of a first combustion cycle, with the help of a first sensor element, determine a first parameter value representing a physical quantity for combustion in said combustion chamber (201) , and

- based on said first parameter value, control the combustion during a subsequent part of said first combustion cycle, so that during said control the combustion in said subsequent part of said first

43. System according to claim 42, characterised in that said combustion engine consists of one out of the group : a vehicle engine, a marine engine, an industrial engine .

44. Vehicle (100) , characterised in that it comprises a

system according to claim 42 or 43.