WO2014175819A1 - Method and system for control of an internal combustion engine - Google Patents

Method and system for control of an internal combustion engine Download PDF

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Publication number
WO2014175819A1
WO2014175819A1 PCT/SE2014/050493 SE2014050493W WO2014175819A1 WO 2014175819 A1 WO2014175819 A1 WO 2014175819A1 SE 2014050493 W SE2014050493 W SE 2014050493W WO 2014175819 A1 WO2014175819 A1 WO 2014175819A1
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WO
WIPO (PCT)
Prior art keywords
combustion
during
control
subsequent
cycle
Prior art date
Application number
PCT/SE2014/050493
Other languages
French (fr)
Inventor
Ola Stenlåås
Kenan MURIC
Original Assignee
Scania Cv Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to SE1350510-2 priority Critical
Priority to SE1350510A priority patent/SE539031C2/en
Application filed by Scania Cv Ab filed Critical Scania Cv Ab
Publication of WO2014175819A1 publication Critical patent/WO2014175819A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D35/00Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/025Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining temperatures inside the cylinder, e.g. combustion temperatures
    • F02D35/026Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining temperatures inside the cylinder, e.g. combustion temperatures using an estimation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D35/00Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/30Controlling fuel injection
    • F02D41/38Controlling fuel injection of the high pressure type
    • F02D41/40Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/402Multiple injections
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/14Introducing closed-loop corrections
    • F02D41/1401Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1412Introducing closed-loop corrections characterised by the control or regulation method using a predictive controller
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/02Circuit arrangements for generating control signals
    • F02D41/14Introducing closed-loop corrections
    • F02D41/1401Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1433Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/30Controlling fuel injection
    • F02D41/38Controlling fuel injection of the high pressure type
    • F02D41/3809Common rail control systems
    • F02D41/3827Common rail control systems for diesel engines
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine management systems

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 the said combustion chamber (201), wherein the combustion in said combustion chamber (201) occurs in combustion cycles. During a first part of a first combustion cycle, with the help of a first sensor element, a first parameter value representing a physical quantity for combustion in said combustion chamber (201) is determined. The method comprises: - 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 during said subsequent part of said first combustion cycle, the combustion is controlled with respect to a representation of a heat loss resulting 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.

In relation to vehicles in general, and at least to some extent heavy goods vehicles in particular, development is constantly ongoing in the quest, for fuel efficiency a d reduced exhaust emissions. Due to e.g. increased government interests concerning pollution and air quality in e.g. urban areas, emission standards and regulations have been drafted in many jurisdictions. When heavy goods vehicles are driven, such as cargo vehicles, buses and similar, vehicle economy has over¬ time gained an increasing impact on profitability in the business where the vehicle is used. The main expenditure items for the day to day operation of a vehicle consist, apart from the cost of acquisition of the vehicle, of the vehicle

driver's salary, costs of repair and maintenance, and fuel for driving the vehicle. Thus it is, within each one of these areas, important to attempt to reduce the costs to the extent possible .

Emission regulations often consist of sets of requirements defining acceptable limits for exhaust emissions in vehicles equipped with combustion engines. For example, levels of nitrogen oxides (NOx) , hydrocarbons (HC) and carbon monoxide (CO) are often regulated. These emission regulations may also e.g. handle the occurrence of particles in exhaust emissions.

In an effort to comply with these emission regulations, the exhausts caused by the combustion of the combustion engine are treated (purified) . For example, a so-called catalytic

purification process , co pris ing one or severa1 cata1ysts , may be used. The treatment of exhausts may also comprise other- components , e.g. particulate filters. The occurrence of unwanted compounds in the exhaust flow resulting from, the combustion engine is to a large extent caused by the combustion process in the combustion engine's combustion chamber, at least partly depending on the amount of fuel consumed in the combustion. For this reason, and due to a very large part of the operating economy of primarily heavy- goods vehicles being controlled, as set out above, by the amount of fuel consumed, great efforts are also made to make the combustion engine's combustion more efficient in an effort to reduce emissions and fuel consumption,

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, wherein the combustion in said combustion chamber occurs in combustion cycles.

During a first part of a first combustion cycle, with the help of a first sensor element, a first parameter value is determined which represents a physical quantity in connection with combustion in said combustion chamber, 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 during said subsequent part of said first combustion cycle, the combustion is controlled with respect to a representation of a heat loss resulting during said combustion.

As mentioned above, the efficiency of the combustion engine has a great impact on a vehicle's total economy, in particular with respect to heavy goods vehicles. For this reason, it is often desirable that the combustion is controlled in a manner that entails as efficient a combustion as possible.

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 present invention pertains to a control of the combustion process where circumstances during the course of an ongoing combustion cycle may be determined, where control may be carried out during an ongoing combustion with the objective of controlling the combustion toward a desired result.

At the combustion in a combustion engine, a part of the energy relea.sed at combustion will result in work done on the

combustion engine's output shaft, i.e. the force which may be used to drive the vehicle. Also, a part of the combustion's energy will be used to neat the exhausts resulting from combustion, and a part of the energy released during the combustion will be lost in pure heat losses, i.e. to heat the combustion engine. These heat losses have several

disadvantages. First, the heat losses reduce the efficiency of the combustion engine, with increased fuel consumption and therewith associated fuel costs, as a consequence. In

addition, the arising heating of the combustion engine must be taken care of by the vehicle's cooling system, with the associated, load on the latter. Also, the available heat, energy in the combustion's exhausts is reduced, heat energy which may often be desirable, e.g. for heating of exhaust treatment components such as catalysts, particulate filters, etc.

According to the present invention, the course of the

combustion is therefore controlled with respect to the heat loss which arises during combustion, i.e. the energy which is not used, for work or heating of exhausts, a d the control may e.g. be controlled toward a minimisation of the resulting heat loss arising during the combustion.

Control, according to the present, invention, may be achieved by, during a first part of a combustion cycle, determining a parameter value relating to a physical quantity for the combustion, e.g. a pressure prevailing in the combustion chamber .

Based on this parameter value, e.g. a prevailing pressure, the combustion may then during a subsequent part of the combustion cycle be controlled with respect to the heat loss which arises. The combustion may e.g. be controlled by determining an injection strategy for application at. a subsequent

injection, where, at the determination of the injection strategy the resulting heat loss may be predicted by way of estimation, so that an injection strategy, e.g. one injection strategy out of several injection strategies, may be selected based on an estimated heat loss for the respective injection strategy .

For example, a control parameter for the control of the combustion during said subsequent part of said combustion cycle may be determined, where, at said determination - with the use of said first parameter value - an expected heat loss may be predicted with an estimation for at least two control alternatives for said subsequent part of said combustion cycle, where the control alternative which is deemed to be most suitable may be used for the control of the subsequent combustion .

According to the invention, the combustion may thus, during the subsequent part of said first combustion cycle, be

controlled based on a representation of a heat loss resulting during said first combustion cycle, estimated with said first parameter value, and control may e.g. be arranged to be regulated toward a desired heat loss for said first combustion cycle .

Further, control may be arranged to determine a desired heat loss for said subsequent part of said combustion cycle, based on the -work to be achieved during said first combustion cycle, so that the combustion may be controlled during said

subsequent part of said first combustion cycle toward said desired heat loss.

Said first parameter value may be arranged to be determined when a part of said first combustion cycle has lapsed, and e.g. when combustion of fuel has been started during said first combustion cycle. Thus, said first parameter value allows for a good estimation, since estimation is carried out with starting- values consisting of actually prevailing

conditions in the combustion chamber, after the combustion cycle has been started. According to one embodiment, said first parameter value is determined when the combustion has been initiated in said first combustion chamber, so that the regulation of the combustion during the subsequent part of said first combustion cycle may be carried out based on prevailing circumstances in the combustion chamber, after the combustion of fuel has been initiated.

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 s ows 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. 1.

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

Fig. 1 in more detail.

Fig. 3 shows an example embodiment according to the present invention .

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.

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

Fig. 6 shows an example of MPC .

Detailed description, of entbodiKients

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 engine 101 is controlled by the engine'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 emissions 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 in ectors, 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.

Fig. 2 snows schematically an example of a fuel injection system for the combustion engine 101 exemplified, in Fig. 1A. ρ

The fuel injection system consists of a so-called Common Rail system, but the invention is equally applicable in other types of injection systems. Fig. 2 shows only 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, so that several 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 at a large extent be controlled, 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 i to consideration in connection with this control.

According to the present invention, e.g. injection times and/or duration for the respective injections and/or injected fuel amounts are adapted during ongoing combustion, based on data from the ongoing combustion. As mentioned above, the energy released during combustion i a combustion engine will partly result in work, achieved, but. also result, in heating of exhausts and heat losses in the form of heating of the

combustion engine. According to the invention, the combustion is controlled with regard to the heat loss which arises during combustion, e.g. through a control whose objective is to minimise the heat, losses at combustion while the desired work may still be achieved.

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. 1Ά-Β.

In general, control systems in modern vehicles consist, of a communication 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 o ly the co trol 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 shown 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 .

The control is often controlled by programmed instructions. These programmed instructio s 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 are arranged 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 sendi g 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 the control according to the invention of the combustion process should be carried 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 started. Alternatively, the control action may be arranged to be carried out e.g. as long as the combustion engi e's combustion is not. be co trolled according to some other criterion. For example, there may be situations where it is desirable that the control action is carried out based on factors other than primarily heat losses. According to one embodiment, simultaneous control of the combustion is carried out with respect to heat losses and at least one additional control parameter. For example, a weighing up may be carried out, where the control parameters' prioritisation on fulfilment of a desired control result may e.g. be arranged to be controlled according to some suitable cost function.

The method according 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 engine, 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, an injection schedule is determined which is expected to result in a desired heat loss during the

combustion, e.g. an injection schedule which is expected to minimise the resulting heat loss during the combustion of the combustion cyc1e . 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 is to 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 corabustion ai r pressu res , et c . , he re tabu1ated 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 wish regarding low heat loss.

These injection schedules may consist of the number of

injections and respective characteristics in the form of e.g. point in time (crank angle position) at 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, and e.g. be calculated/measured with the objective of resulting in a minimal heat loss.

According to the present embodiment, such a predetermined injection schedule is therefore applied in step 303, where this predetermined injection schedule is selected based on prevailing conditions and the work requested from the

combustion engine, and e.g. by way of table lookup. According to one embodime t, the injection schedule is

determined entirely according to e.g. the calculations

displayed below, where e.g. different injection schedules defined in advance may be compared to each other to determine a. most preferred injection schedule, but in the calculation example exemplified below, however, the calculations are only applied after the injection has been initiated during the combustion cycle. Since specific assumed conditions probably result in the same preferred injection schedule each time, it. may be advantageous to select an injection schedule through some type of lookup before a combustion cycle, and thus to reduce the calculation load, so that the calculation as set out below is th s carried out only after the injection has started. In addition to the example below of how the injection schedule may be determined, other models with a similar function may alternatively be applied.

According to the present eiribodiment, in step 303 a pre-defined injection schedule at the start of the combustion cycle is thus determined, 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 the 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 predetermined 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

injec ions inspi are carried out during onΘ 3.nd 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 of obtaining some certain heat loss, e.g., under prevailing conditions, a minimal heat loss - i.e. given the prevailing combustion engine work, a heat loss as small as possible - during the combustion. A first injection inspi is carried out, and in step 304 it is determined whether said first injection inspi has been carried out and, if so, the method continues to step 305, 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 306 while i is

incremented by one for the next injection. Further, with the continuo s 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 actual heat loss arising will deviate from the estimated heat loss. In

addition, the subsequent part of the combustion cycle, and therefore the heat loss, will be impacted.

If the combustion after the first, i jection i spi has thus proceeded just as expected, the conditions in the combustion chamber will correspond to the conditions intended for the injection, and likewise the hitherto resulting pressure change (the pressure track as set out below) i the combustion chamber will correspond to the expected pressure change up to this point. As soon as the conditions deviate from the

intended conditions, however, the pressure change during the combustion will deviate from, the expected pressure change.

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, at the next injection will not correspond to the expected conditions. As explained, below, there is a direct, connection between the pressure in the combustion chamber and the resulting heat losses, so that any deviations in pressure will also result in deviations from expected neat losses.

In practice, the actual pressure changes during the combustion (pressure track} will very probably deviate from the predicted, pressure track during the course of the combustion, because of 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 in ection profile. This prediction of the pressure track may e.g. be carried out as described below.

Fig. 4 also displays an actual pressure track 402 up to the crank angle position φχ, which constitutes the prevailing position after said first combustion has been carried out. In step 306, the pressure ρφι in the combustion chamber is

determined with the use of the pressure sensor 206 after the first injection inspi has been carried out, at the crank angle position cpi . Preferably, the pressure in the combustion chamber is determined substantially continuously, e.g. at each crank angle degree, every tenth crank angle degree or with another suitable interval during the entire combustion. As may be seen in Fig. 4, the actual pressure track up to (pi deviates from the estimated pressure track 401, and the actual pressure ρφι also deviates at (pi from the estimated pressure ρΦι est, according to the pressure track 401. The above means that the hitherto resulting heat loss has, with great probability, also deviated from the expected heat loss up to the crank angle position φχ .

Since the pressure ρφι in the combustion chamber after the first injection inspi has been carried out deviates from the corresponding estimated pressure ρφι est at the crank angle position φ-j , the cond.itions in the combustion chamber at the time of 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 used. Thus it is not at all certain that the desired minimisation of heat losses will be achieved during the combustion cycle. Therefore it also not certain that it is the originally determined

injection schedule which constitutes the most preferred injection schedule in an effort to achieve the desired heat loss . In step 307, an in ection schedule is therefore again

determined in order to reduce the heat losses, e.g. with the objective of attempting to minimise the heat losses during the combustion cycle, or the remaining part of the combustion cycle. The control may e.g. be ca ried out according to the calculations displayed below, alternatively according to other applicable calculations with a similar objective, and be repea ed as set out below during an ongoi g- 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, such as after each injection, or during a.n ongo ing xnj ect ion .

At the estimation of heat losses, according to the invention, a model is used, which describes the heat losses arising during the combustion. This model may be of different type, and e.g. consist of a computer■■ driven model L^"! = f(Qh, , u) where Qhi

di

constitutes the energy which is used in heat loss, and where u constitutes a control variable, (e.g. the fuel supply to the combustion), i.e. a model which is prepared by determining a result for a large number of input parameters, where mav dt then be tabulated for a large number of conditions, such as different loads, engine speeds, air pressure, etc., which are known to a person skilled in the art within this area of technology.

Another alternative, which also constitutes the alternative applied in the present example, is the use of a physical model for heat losses during combustion in the combustion chamber. This model may consist of some applicable model and, according to the present example, the Woschni model, familiar to a person skilled in the art, is used tor the heat losses hi during combustion in a combustion engine.

Heat losses in a combustion process are described primarily by temperature and pressure in the combustion chamber (in this case the cylinder}, and the gas movement. Temperature and pressure, however, are related to each other via the general gas law, which, as set out below, makes it possible to

describe the heat losses as a function of pressure without any explicit knowledge about the temperature.

According to Woschni, the heat released at combustion may be modelled as:

^ = h-S(<p)-AT, (1) where h = 3.26B~0-2p°-8T~QSSw0-8, w =

Calculation of the parameters are generally well described in prior art, and therefore some are only briefly described herein, where:

B = cylinder diameter, p = cylinder pressure,

T = temperature in the cylinder, w = characteristic gas speed, here approximated to CtSp

Sp = the piston's average speed in the cylinder, which may e.g. be tabulated, in the control system for different engine speeds, or calculated with the help of the engine speed and the stroke of the piston,

Ci constitutes a defined coefficient which, according to one example, may be set. as 2,28 with the addition of a piston average speed dependency. The coefficient, is

determined/calibrated, as is generally known, according to the specifications of oschni.

S((p) = the wall area (cylinder wail and the area for the combustion chamber's delimitation "upwards" and "downwards" , respectively) in the combustion chamber as a function of the crank ang1e, and

ΔΓ constitutes the temperature difference between, the

temperature of the gas in the combustion chamber and the combustion chamber' s wall temperature.

According to equation (1), there is thus an explicit

connection between the heat loss during combustion and the average temperature of the combustion gases. This explicit temperature connection may be eliminated by estimation of the heat loss with the use of the general gas law: pV = nRT (2 }

Equation (2) may be re-written with crank, angle dependency (φ), so that the combustion gas temperature Γ may be expressed as : η(φ)ίί

Thus, equation (1) may be re-written with the help of equation (3) as follows: h = 3.26iT°-V8 f^¾~°'558 - 3.20/Γ 0·V25f-^-V0'55 w0'8 ( 4 ) ν(φ), i.e. the combustion chamber's volume as a function of crank angle may advantageously be tabulated in the control system's memory or be calculated, in an applicable manner,

dv

where also — αφ, as used below, rnav be calculated. The substance amount n, i.e. the substance amount or gas in the combustion chamber, will change over time (crank angle) as the combustion progresses . The substance amount n changes in connection with the chemical reactions which occur during the combustion. This change, however, is normally only one or a few percentages, so that the substance amount nf according to one embodiment may be assumed to consist of the substance amount before the combustion, so that the substance amount η(φ may thus be assumed to be constant. According to one

embodiment, however, the change in the substance amount during combustion may be estimated in order to provide a more

accurate estimation of eat losses during the combustion. This is described below.

Regarding the cylinder wall's temperature Twaii, this may, with good approximation, be assumed to be constant and determined in some applicable manner, e.g. with an applicable temperature sensor, where AT may be estimated according to:

ΔΓ=«£__Γι^ (5)

With parameters according to the above, the heat losses may thus be estimated as a function of crank angle according to equation (4), where already arisen heat losses may be

estimated with the use of sensor signals from the pressure sensor .

The estimation of the total expected heat losses, or of those for the subsequent part of the combustion cycle, during the combustion thus requires knowledge about the variation of the pressure p during the combustion. The pressure may p be

determined with the use of said pressure sensor, so that continuous sensor signals may give measured values for p at applicably irequent intervals/crank angle degrees in order to estimate ~ for the cart of the combustion which has already

αφ

lapsed, and so that an actual heat loss may be estimated for the part of the combustion which has already lapsed based on actual pressure data. Pressure change is expressed in crank angle degrees φ, which entails an elimination of the

combustion engine speed dependency at calculations.

The present invention strives, however, to actively control, e.g. with the objective of minimising- or controlling toward another applicable level, heat losses during combustion, which may be carried out by predicting the expected pressure track in the combustion chamber for the subsequent part of the combustion cycle, so that also the expected heat loss for the entire combustion is estimated.

This also means that the expected heat loss may be estimated for several different scenarios at combustion, such as different injection schedules , where the respective injection schedule will give rise to a specific pressure track, e.g. the pressure track shown in Fig. 4, which is estimated for the s ecific inject io schedu1e .

At estimation of the pressure track, a model of the combustion may be used, and, as is familiar to one skilled i the art, the combustion may be modelled according to equation (6): dQ - Kcalibrate (Qfuel - Q) (6)

, where KcaUbrate is used to calibrate the model. KcaUbrate 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 parΤΓ.icu i r o the design of the injector nozzles (spreaders) ,

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

O consists of amount of energy burned. The combustion dO is thus proportionate to the injected fuel amount minus the hitherto consumed fuel amount. The combustion clQ 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 which arises 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: ( - ini , start)k)- < (t - (¾ . end )¾ )

Figure imgf000026_0001

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

f(m)u

dt where m constitutes the injected fuel amount, and f (m) e.g. depends on the injection pressure, etc. f (m) may e.g. be measured or estimated in advance. The energy value QLf1v 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 (6} may be resolved and the heat release Q may be determined as the combustion progresses.

Further, with the use of a predictive heat release equation, where a part of the released neat energy will be used for desired work and another part consists of heat losses, the pressure change in the combustion chamber during the entire combustion may be estimated as:

Figure imgf000027_0001

where γ generally constitutes the heat capacity ratio, i.e. , where CB and/or Cv are generally prepared and

Figure imgf000027_0002

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„ value, so that this may be

determined, for the calculations above with a good accuracy, in advance or during e.g. ongoing combustion. Alternatively, C0 and/or Cv may be approximated in a suitable manner. Integration of equation (9) entails the following result: f f fdQ γ dV\ (J - 1\

V - V uai +J dp = pinitiai +J (—-—p—J (—J d<p (10) Pinital 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 i step 307 after an injection has been carried out, pinitai may constitute the then prevailing pressure, as determined by the pressure sensor 206, i.e. ρφι in the present example. Thus the pressure p in the combustion chamber may be estimated for the entire combustion, i.e. an expected curve corresponding to the curve 401 in Fig. 4 may be estimated, so that the heat loss for the entire combustion may also be estimated by using the above equations ,

The heat loss will thus depend on the pressure track, which in turn depends on how fuel is supplied to the combustion. In principle, the minimisation problem when minimising heat losses may be formulated as a minimisation of equation (11):

Figure imgf000028_0001

, where I O represents the opening of an inlet valve and EVO represents the opening of an exhaust valve. It is thus

primarily the pressure in the combustion chamber which

constitutes a control variable at the minimisation of equation (11). The cylinder geometry, including the cylinder diameter, is fixed, and. the gas speed may be difficult to control during an ongoing combustion. The substance amount is relatively constant during the combustion (and may, according to the above, according to one embodiment, be assumed to be constant} and, in addition, unsuitable, at least for being the only control parameter, since the substance amount to a large extent is controlled by the fuel supplied, which in turn to a great extent is controlled by the requested work.

Minimisation of equation (11) thus constitutes a minimisation problem which consists of finding a pressure track resulting in as low neat losses as possible. This, however, with the constraint that work done on the combustion engine's output shaft is maintained, si ce other ise there is a great

probability that only a small part of or no work will be achieved to the extent that only the heat loss is minimised, so that the thermal efficiency is optimised at the expense of low output.

Control of the pressure in the combustion chamber may thus be carried out by cont olling the fuel in ection, and, i step 307, by carrying out an estimation of the heat losses 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, minimises the neat losses, or controls these toward another applicable level, during the combustion.

Thus, in step 307, an injection schedule may be determined, such as an injection schedule among several defined injection schedules, which best minimises the heat losses according to the above equations, where such 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 low/desired heat loss.

Hitherto the entire injection schedules for the remaining combustion have been evaluated, but the minimisation may also be arranged to be carried out only for the subsequent

injection after a previous injection, so that, subsequent injections may be handled 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, so that this also gives rise to a combustion, and thus a heat release and a pressure track, where this will also probably 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.

Thus, in step 307, after a new subsequent injection has been carried out, a new injection strategy for the remaining injections, alternatively the subsequent injection, may be calculated by using the above equations, and the method then reverts to step 304 in order to carry out the subsequent fuel inj ection a.ccording to the ne inj ect. ion strategy ca1cu.1ated. in step 307, still with consideration for the work to be achieved during the combustion, which is normally controlled by some superior 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 control system, e.g. a cruise control function. The control may thus be arranged to be carried out after each injection i, and when all subsequent injections i have been carried out, the method reverts from step 305 to step 301 to control a subsequent combustion cycle.

At the above calculations, after each injection, the current pressure determination ρφ1 is calculated by using the pressure sensor 206 as Pin iai described above, in order to again predict, neat loss to determine a new injection schedule based on the now prevailing conditions in the combustion chamber, but now thus with data obtained a little further along into the combustion. That is to say, ρ,,,ι after the first combustion and the similarly determined ρφι for subsequent injections, where thus initial changes at calculations during the combustion cycle, and where fuel injections are adapted according to prevailing conditions after each injection, and,, as a

consequence, where the injection schedule may change after each injection.

The present invention thus provides a method which adapts the combustion as the combustion progresses, and comprises

generally, based on a first parameter value which is

determined after a first part of the combustion has been completed, controlling a subsequent part of the combustion during one and the same combustion cycle, where the combustion is controlled with respect to heat losses during the

corabustion rocess.

As set out above, the expected heat loss may thus be estimated for several different alternative injection schedules for the remaining injections, so that, the injection schedule resulting in the most advantageous heat loss may be selected when the next injection is to be carried out. According to the present invention, the combustion is thus adapted during ongoing combustion based on deviations from the predicted combustion and, according to one embodiment, each time an injection ins i has been completed, as long as additional injections are to be carried out.

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, as set out above, the substance amount at combustion has been assumed to be constant, which may be assumed to constitute a good approximation. The substance amount, will, however, in practice vary as the combustion progresses, which is why, according to one embodiment, the substance amount, nis estimated as follows. The change of the substance amount during the combustion may e.g. be modelled as: n = ( l - nbefore comb (λ, mfuel ) + ϊ-nall comb (A,mfuel ) (12)

The substance amount n will, during the course of the

combustion, transition from a substance amount prevailing before the combustion nhefore comh to a substance amount. na!, comb when all the fuel injected during the combustion cycle has burned. nbef0!V romh is determined with the help of A, i.e. the fuel/air ratio, and the supplied amount of fuel ri Uei , and the total substance amount for fuel and combustion air is obtained.

Here, any EGR reversal may also be taken into account, since this impacts the substance amount in the combustion gas. Qtotal specifies the total fuel energy which is supplied to the combustion during the combustion cycle. Qnow constitutes the energy amount which has hitherto been burned, and is

determined from the equation (9) and/or with the help of the pressure sensor's signals and heat release according to equation (13) : (13)

Figure imgf000033_0001

Thus the heat release Q (φ) , and therefore n (φ) in the event n (φ is to be estimated as set out above, may be calculated as dQ

the combustion progresses by integrating -7-, where cp

ά.φ

constitutes the crank angle degree.

Further, the control has hitherto been described in a manner where the characteristics for a subsequent injection are determined, based on prevailinq conditions in the combustion chamber, after the previous injection. The control may, however, also be arranged to be carried out continuously, where pressure dete tio s ma be ca ried out with the help of the pressure sensor also during an 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, the fuel, supply during the combustion may comprise two fuel injections, where e.g. only the second or both injections 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.

Regarding 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 cha ges in re1eased energy .

As the number of fuel injections carried out during a

combustion cycle increases, the number of parameters that may change also increases, while the work achieved must be

maintained.. 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

inj ections .

In such situations, there may be several equivalent injection strategies, which result in substantially the same heat loss, and this introduces an undesired 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 the remaining injections 503-505 are treated as one single virtual injection 506, i.e. the injection 506 is treated as one injection with a fuel amount substantially corresponding to the total fuel amount for the injections 503-505, and where a distribution may be made between the injection 502 and the virtual injection 506, By proceeding in this manner, the shifting which occurs between inspa 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.

Once the injection 502 has been completed, the method is repeated., exactly as above, with a new determination of an injection schedule, in order to minimise eat losses, but with the injection 503 as a separate injection, see Fig. 5B, and the injections 504, 505 jointly constituting one virtual injection with a distribution 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. MFC (Model Predictive Control} in the control according to the invention.

One example of MFC is shown in Fig. 6, where the reference curve 603 corresponds to the expected o'evelopraent for the accumulated heat losses during the heat release during the

* — EVG

combustion cycle, i.e. j _ h S(p) LTdt for the selected injection schedule. The curve 603 thus represents the

development for the accumulated heat losses which is desired during the combustion cycle. This curve may e.g. consist of a (lowest) level for heat loss, which may realistically be achieved during a combustion cycle at the given load and prevailing engine speed, and may, advantageously, be

determined in advance, e.g. with applicable calculations and/or measurements on the engine type, so that, these data may be stored in the control system's memory as functions of e.g. engine speed and load. This entails also that the combustion need not be controlled only toward a heat loss prevailing at each time, but may also be arranged to be controlled toward an expected heat loss development, e.g. the curve 603 in Fig. 6, where each injection may have as its objective to result in a hitherto accumulated neat loss which, at some given point in time, amounts to a corresponding point on the curve 603. The curve 603 may in one embodiment consist of a curve

representing the expected heat loss at each point, i.e. not an accumulated heat loss, so that the neat losses may be

controlled toward this reference value curve instead.

The solid curve 602 up to the time k represents the actual heat losses arising to date and which have been calculated, as set out above, by using actual data from the crank angle resolved pressure transmitter. The curve 601 represents the predicted heat loss development based on the predicted

injection profile, and thus constitutes the heat loss development which is expected. Dashed injections 605, 606, 607 represent the predicted control signal, i.e. the injection profile which is expected to be applied, and 60S, 609

represent the already completed injections.

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 heat loss 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 achieve a combustion with controlled heat losses.

According to the above, heat losses in combustion may thus be estimated for several different alternative injection

schedules for the remaining injections, so that an injection schedule which results in the most advantageous, e.g. the lowest, heat loss 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 s imulta.neou.sly effecting co trol also based on othe - parameters. For example, an injection schedule may also be partly selected based on one or several of the perspectives pressure amplitude, pressure change speed, exhaust

temperature, work achieved in the combustion chamber, or nitrogen oxides generated at combustion as an additional criterion, in addition to being selected based on heat losses, where such determination may be carried out according to one of the parallel patent applications mentioned 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 combustion during said first combustion cycle with respect to a temperature resulting in said subsequent combustion.

Further, the parallel application "METHOD AND SYSTEM FOR

CONTROL OF A COMBUSTION ENGINE III" (Swedish patent

application, application number: 1350509-4} shows a method to, during a first combustion cycle, control combustion during a subsequent part of said first combustion cycle with respect to work achieved during the 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, during a first combustion cycle, estimate a first measure of nitrogen oxides resulting at combustion during said first combustion cycle, and based on said first measure, to co trol the

combustion during a subsequent part, of said first combustion cycle .

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 at combustion during said first combustion cycle, and based on said first measure, to control the

combustion during a subsequent part of said first combustion cycle .

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 which pressure the heat losses may then be estimated. As an alternative to using 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 heat loss at 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 control the pressure in the combustion chamber and. thus also the heat losses .

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 engi e may also be combi ed, with sensor signals from other sensor systems where the resolution of the crank, angle level is not available, e.g. another pressure

transmitter, MOx sensors , NH3 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. eat 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, applicable to any vessels/processes where particle filter systems as per the above are 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 invent! nd 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 pertains to and

comprises 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, a first parameter value representing a physical quantity for combustion in said combustion chamber (201) is determined, and
- based on said first parameter value, the combustion during a subsequent part of the said first combustion cycle is controlled, so that, at said control of the combustion during the said subsequent part of said first combustion cycle, the combustion is controlled with respect to a representation of a heat loss resulting during said combustion.
2. Method according to claim 1, further comprising:
- based on said first parameter value, estimating a representation of a heat loss resulting during said first combustion cycle and
- based on said estimated resulting heat loss,
controlling the combustion during said subsequent part of said first combustion cycle,
3. Method according- to claim 1 or 2, further comprising- :
- based on the work to be achieved during said first combustion cycle, determining a desired heat loss for said first combustion cycle, and
- controlling the combustion during said subsequent part of said, first combustion cycle toward said desired heat 1oss .
4. Method according to any of claims 1-3, further
comprising :
- based on the work to be achieved during said first combustion cycle, determining a desired heat loss for said subsequent pa t, of said combustion cycle, and
- controlling the combustion during said subsequent part of said first combustion cycle toward said desired heat 1oss .
5. 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.
6. 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.
7. Method according to any of the previous claims, also
comprising :
- estimating an expected heat loss at combustion during said first combustion cycle at a number of different, times/crank angle positions during said first combustion cycle, and
- controlling the combustion during a subsequent part of said first, combustion cycle, based on the respective estimated heat loss.
8. 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 ,
- estimating a respective heat loss resulting during said first combustion cycle during the combustion, and
- controlling combustion during a subsequent part of said first combustion cycle, following determination of the respective parameter value based on the respective esti ated heat 1oss ,
9. Method according to any of the previous claims, also
comprising :
- estimating a representation of a heat loss resulting hitherto during said first combustion cycle, and
- controlling said subsequent part of said combustion cycle, at least partly based on said representation of said heat loss resulting to date during said first combustion cycle.
10. Method according to any of the previous claims, also comprising :
- determining at least one control parameter for the control of combustion during said subsequent part of said combustion cycle, and
- at said, determination, estimating an expected heat loss for at least two control alternatives for said subsequent part of said combustion cycle, with the use of said first parameter value ,
11. Method according to any of the previous claims, wherein, at the said, control, a heat loss resulting during said combustion cycle and/or said subsequent, part of said combustion cycle is estimated with the use of one or several of: a data-driven model, an empirical model, a physical model. 12, Method according to one of the claims 9-11, wherein, at the estimation of said heat loss, a pressure change for said subsequent part of said combustion cycle is
estimated, with the use of an estimation of a heat release during said combustion, and where said heat loss is estimated based on said estimated pressure change.
13, Method according to claim. 12, wherein said estimated pressure change constitutes an estimated pressure track.
1 , Method, according to claim 12 or 13, further com rising estimating said heat release based on the amount of fuel for supply to said combustion,
15. Method according to one of the previous claims, wherein said first parameter value represents a pressure
prevailing in said combustion chamber (201).
16. 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) .
17. Method according- to one of the previous claims, further comprising, during said control of said combustion, during said subsequent part, of said combustion,
determining an expected heat loss for said combustion cycle and/or for said subsequent part of said combustion cycle for at. least, one first and one second control alternative, respectively, and
- among several control alternatives, selecting one control alternative for control of said subsequent part of said, combustion cycle.
18. Method according to any of the previous claims, also comprising : 4 "λ
- at said control, evaluating at. least a first and a second control alternative, respectively, so that either the first or second control alternative, whichever is expected to result in the smallest heat loss, is
selected.
19. Method according- to claim 17 or 18, further comprising to evaluate at least said first, and said second control alternative, respectively, wherein either said first or second control alternative, whichever is expected to result in the smallest heat loss during said subsequent part of said first combustion cycle, is selected.
20. Method according- to one of claims 17-19, wherein said
control alternative consists of alternatives for the supply of fuel during said subsequent part of said combustion cycle.
21. Method according to any of claims 17-20, wherein fuel supply to said combustion chamber (201) is controlled through control of fuel injection with at least one fuel i ector (202) .
22. Method according to any of claims 17-21, wherein at least one fuel injection is carried out during said subsequent part of said combustion cycle, wherein, during said control, the fuel amount and/or injection duration and/or injection pressure is controlled for said fuel injection.
23. Method according to any of claims 17-22, wherein at least two fuel injections are carried out during said
subsequent part of said combustion cycle, wherein said combustion is controlled also after said first of said at least two injections of fuel. 24, Method according to any of claims 17-23, wherein, during control of said combustion, at least three fuel
injections are carried out during said subsequent part 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.
25. Method according to any of claims 17-24, wherein control of combustion during said subsequent part of said first combustion cycle is carried out at least partly through control of injection of fuel to said combustion chamber (201) during an ongoing fuel injection.
26. Method according to any of c.1aims 17 -25, further
comprising to change a distribution of fuel amounts between at least two fuel injections during the control of fuel injection to said combustion chamber (201).
27. Method according to any of claims 17-26, further
comprising applying a predetermined supply of fuel at the start of the combustion cycle, wherein control is carried out after a first injection has at. least been started, but before the fuel injection during said first
combustion cycle has been completed.
28. Method according to any of the previous claims, further comprising carrying out a first injection of fuel into 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 injection has at. .least par11y been completed. 29, 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) ,
30, Method according- to any of the previous claims , wherein said control is carried out for a number of consecutive combustion cycles,
31. Method according to any of the previous claims, wherein said first parameter value representing 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 .
32. Method according to any of the previous claims, wherein said first parameter value is determined by using one or several from the group: a cylinder pressure transmitter, a knock sensor, a strain, gauge, a speed sensor, an ion current sensor.
33. Method according to any of the previous claims, also
comprising :
- based, on said first parameter value, controlling combustion in said combustion chamber toward a first pressure or temperature curve relating to
pressure/temperature change in said combustion, chamber during said first combustion cycle, wherein said pressure or temperature curve represents a desired heat loss during said combustion.
34. Method according to any of the previous claims, further comprising, during at least a part of said first combustion cycle:
- continuously determining said first parameter value, - continuously, and based on said determinations of said first parameter value, estimating a heat loss resulting during said first combustion cycle during combustion, and
- continuously controlling combustion during said at least one part of said first combustion cycle based on said estimated heat loss.
35. A 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 1-24.
36. A computer program product, comprising a computer-readable medium and a computer program according to claim 35, wherein said computer program is comprised in said computer-readable medium .
37. 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 in said combustion chamber (201) occurs in combustion cycles, wherein the method is characterised in that the system comprises:
- elements 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
- elements (115) to, based on said first parameter value, control combustion during a subsequent part of said first, combustion cycle, so that during said control of the combustion during said subsequent part of said first combustion cycle, the combustion is controlled with respect to a representation of a heat loss resulting during said combustion. , System according to claim. 37, characterised in that sa combustion engine consists of one out of the group: a vehicle engine, a marine engine, an industrial engine. , Vehicle (100), characterised in that it comprises a system according- to one of the claims 37 or 38.
PCT/SE2014/050493 2013-04-25 2014-04-24 Method and system for control of an internal combustion engine WO2014175819A1 (en)

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SE537190C2 (en) * 2013-04-25 2015-03-03 Scania Cv Ab Method and system for controlling an internal combustion engine through control of combustion in an internal combustion chamber during the current combustion cycle
SE537308C2 (en) * 2013-04-25 2015-04-07 Scania Cv Ab Method and system for controlling an internal combustion engine through control of combustion in an internal combustion chamber during the current combustion cycle
SE539296C2 (en) * 2013-04-25 2017-06-20 Scania Cv Ab Method and system for controlling an internal combustion engine by controlling the combustion in an internal combustion chamber during the current combustion cycle
SE537313C2 (en) * 2013-04-25 2015-04-07 Scania Cv Ab Method and system for controlling an internal combustion engine through control of combustion in an internal combustion chamber during the current combustion cycle

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DE112014001774B4 (en) 2020-01-30
SE1350510A1 (en) 2014-10-26

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