SE1450253A1 - Procedure and system for regulating an internal combustion engine - Google Patents

Abstract

The present invention relates to a method of controlling an internal combustion engine (101), said internal combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said internal combustion chamber (201), wherein combustion in said internal combustion chamber (201) occurs in combustion cycles. The method comprises: - during a first part of a first combustion cycle, estimating a first measure of a specific heat capacity for said first combustion cycle, - based on said first measure, determining a first amount of a first liquid for supply to said combustion chamber (201), and - to said combustion chamber (201) supplying said first amount of said first liquid. The invention also relates to a system and a vehicle. 3

Description

1 FIELD OF THE INVENTION FIELD OF THE INVENTION The present invention relates to combustion meters, and in particular to a procedure for regulating a internal combustion engine according to the preamble of claim 1.

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

Background of the invention The background description below is the background description for the invention, and thus does not necessarily constitute a prior art.

Due to increased government interests regarding pollution and air quality have emission standards and emission regulations regarding emissions from internal combustion engines developed in many jurisdictions.

Such emission regulations often constitute sets of requirements which defines acceptable limits for exhaust emissions in vehicles equipped with internal combustion engines. For example, is often regulated levels of emissions of nitrogen oxides (NO), hydrocarbons (HC) and carbon monoxide (CO). These emission regulations can also e.g. manage the presence of particles in exhaust emissions.

In an effort to comply with these emission regulations, the exhaust gases caused by the internal combustion engine are treated (purified) combustion. For example. can a s.k. catalytic purification process utilized, why oaks & exhaust gas treatment systems, as in e.g. vehicles and other vehicles, usually include one or more catalysts and / or other components. For example. includes exhaust gas treatment systems for vehicles with diesel engines often particle filter. 2 The danger of undesired experiences in the exhaust gas flow resulting from the combustion engine is largely caused by the combustion process in the combustion chamber of the combustion engine, at least in part due to the amount industry that engages in combustion.

For this reason, as well as the fact that a very large part of the heavy economy's economy in particular is governed by the amount of fuel consumed, great efforts are also made to make the combustion engine's combustion more efficient in the effort to reduce emissions. as well as industry use.

Summary of the invention It is an object of the present invention to provide a method of controlling a internal combustion engine. This object is achieved by a procedure according to claim 1.

A method of controlling an internal combustion engine, said combustion engine comprising at least one combustion chamber and means for supplying fuel to said combustion chamber, wherein combustion in said combustion chamber combustion chambers occur in combustion cycles. The procedure includes: - during a first part of a first combustion cycle, estimate one first measure of specific heat capacity for said first combustion cycle, - based on said first mat, determine a first set of a first liquid is supplied to said combustion chamber, and - supply the first quantity of liquid to the said combustion chamber.

In general, when burning in a pre-combustion engine some of the energy released during combustion will 3 result in a leveled work on the output shaft of the internal combustion engine, i.e. the force that can be used to propel the vehicle. Furthermore, part of the combustion energy will be used to heat the results of the combustion the exhaust gases, and one of the energy released during the combustion will dtgi in pure heat losses, ie. for heating the internal combustion engine.

Regarding the heating of the exhaust gases resulting from the combustion, some heating may be desirable, e.g. father that exhaust gas treatment in a post-treatment system shall work pi unwanted sat. However, an unnecessarily large amount of energy can AtgA cause such exhaust gases to heat up.

Regarding the pure heat losses, these have several disadvantages. On the one hand, the heat losses reduce the internal combustion engine efficiency, with increased fuel consumption, and thus associated operating costs, as follows. On the one hand, the heating of the internal combustion engine that arises is taken care of by the vehicle's cooling system, with an associated load on it. The heat losses can also occur at the expense of it available heat energy in the combustion exhaust gases, that is heat energy can be Onskvard, e.g. for heating exhaust gas treatment components.

According to the present invention, such losses can be reduced by adding to the combustion said first liquid, which may consist of a liquid consisting entirely of water, or a liquid which at least partly, or mainly, consists of water. A liquid consisting of water with additives from a corrosive or antifreeze point of view, ie. non-combustion additives, are considered as present application make up water. The said first water can, however, Oven include other types of additives. For example. it may be advantageous to add additives which in themselves may have 4 adverse effect on e.g. reduction of one or more undesirable chemical compounds resulting from the combustion.

The liquid can e.g. constitute an additive for the reduction of nitrogen oxides resulting from combustion in said combustion chamber. During combustion in internal combustion engines, in particular diesel engines, unwanted nitrogen oxides NOR are generated, at least in part due to the excess oxygen that is generally applied during combustion in diesel engines. The additive can for example be an additive containing urea, such as e.g.

AdBlue. Alternatively, the liquid may be an additive intended to reduce other substances resulting from the combustion.

By thus adding a liquid which is at least partially consists of water, and which Or intended to evaporate under the said first combustion cycle, the transition between liquid and gas will absorb heat from the combustion process and thereby reduce heat losses.

The liquid is supplied according to an embodiment at a time which entails that the evaporation takes place wholly or mainly after that the compression phase of the combustion cycle has been performed, and thus during an expansion phase. The evaporation of liquid to gas entails a volume expansion and thus associated pressure increase, which, when evaporating during the expansion phase, at least in part will result in a pa the output shaft of the internal combustion engine acting and thus resulting in a work, with improved efficiency as a result. At the same time, problems with heating, etc. are reduced. According to one embodiment, the liquid is supplied underneath the compression phase of the combustion cycle, with evaporation may occur at least in part during the compression phase.

Such a supply of liquid can suedes entail large danger parts in internal combustion engines. However, it is important that this supply is carried out in a controlled manner, otherwise negative effects may occur. If e.g. liquid remains in liquid form, and thus substantially incompressible form, in the combustion chamber during a subsequent compression can cause great damage, at least if the amount of liquid remaining becomes too large. Likewise, it should be noted that the temperature in the combustion chamber is not allowed to drop, said It is recommended that the combustion of injected fuel be stopped unwanted sat.

According to the present invention, the supply of liquid to the combustion chamber is regulated based on the prevailing conditions in the combustion chamber during the current combustion cycle, i.e. based on the ratio during the combustion cycle below which injection of fluid takes place. This has the advantage that the amount injected can be adapted to radiating conditions, whereby undesired negative effects of e.g. Injection of an excessively large amount of liquid can be avoided.

According to the invention, suede liquid is injected directly into the combustion chamber of the combustion engine by utilizing an appropriate injection means, such as preferably a separate injection means, wherein said first liquid can be injected independently of injection of fuel. This has the advantage that injection can take place at exactly the desired agon glance, and only in situations where it is judged to be advantageous to perform an injection of fluid.

More specifically, injection of liquid according to the invention is performed based on a specific specification for the combustion cycle heat capacity for the gas composition in the combustion chamber.

By estimating specific heat capacity during the current combustion cycle, it can be based on estimated specific 6 heat capacity determines whether the injection of liquid is desirable.

According to one embodiment, a ratio between isobar heat capacitance Cp and isocor heat capacitance Cv is estimated. wherein liquid is injected based on the said ratio.

According to one embodiment, the specifics are estimated heat capacity ratio gamma 7 = K. = or one corresponding ratio.

When determining the applicable amount of liquid for injection the injection can be performed in order to regulate e.g. namnda ratio between isobar specific heat capacity Cp and isokor specific heat capacity CI, against something applicable value, and according to one embodiment, the attitude towards someone is regulated applicable adverse change during the combustion cycle for this condition, where the desired change can be determined in advance, e.g. as a dependence on the crank angle, e.g. expressed as a function or e.g. expressed as a tabulation of e.g. desired value for different crank angles.

Furthermore, estimation of specific heat capacity, as well as for example named pre-existing gamma y, e.g. be arranged to performed at appropriate times, such as each time a significant change in combustion occurs, such as e.g. in the event of a change in the amount of fuel injected. According to one embodiment, however, specific heat capacity is essentially estimated continuously, ie. at appropriately tata intervals, sasom for example at habit crank angle, or at tatter or sparser intervals. Estimation can e.g. be arranged to be carried out as usual a value with respect to the conditions in the combustion chamber is obtained, such as e.g. when a value representing the pressure of the combustion chamber is obtained. 7 The injection of liquid can also be arranged to be carried out individually for each cylinder, i.e. specific heat capacity can be estimated individually for each combustion chamber, whereby injection of liquid can be adjusted individually for respective combustion chambers.

The invention thus enables regulation where e.g. differences between different cylinders can be detected and compensated for by using individual adaptation of the injected amount of liquid for the respective combustion chamber. Goat can be Oven said that the injection of different amounts of liquid into different Combustion chambers can be Onskvard, e.g. to steer certain cylinders against fulfillment of any criterion, and other cylinders against any other applicable criterion, which can also be achieved according to the invention. Furthermore, only one can or a subset of the cylinders be arranged to be controlled according to the invention, while the combustion in other cylinders can be carried out in the usual or otherwise applicable manner.

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

Additional features of the present invention and benefits thereof will be apparent from the following details description of exemplary embodiments and the accompanying drawings.

Brief description of drawings Fig. 1A schematically shows a vehicle in which the present invention can be used. 8 Fig. 1B shows a control unit in the control system of the vehicle shown in Fig. 1A.

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

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

Fig. 4 shows an example of the variation for ratio between isobar heat capacitance Cp and isocor heat capacity Cv during a combustion cycle.

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

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

A shaft 107 emanating from the gearbox 103 drives drive wheels 113, 114 in the usual way via end shaft and drive shafts 104, 105. In Fig. 1A only one axle with drive wheels 113, 114 is shown, but in the usual way the vehicle can comprise more than one axle provided with drive wheels, as well as one or more additional axles, such as one or more standing axles. The vehicle 100 further includes an exhaust system with a finishing system 200 for 9 customary treatment (purification) of exhaust emissions resulting from combustion in the combustion chamber of the internal combustion engine 101 (eg cylinders).

Internal combustion engines in vehicles of the type shown in Fig. 1A often equipped with controllable injectors to supply desired amount of fuel at the desired time in the combustion cycle, as at a specific piston position (crank angle) in the case of a piston engine, to the combustion chamber of the combustion engine.

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

The control signals for controlling the actuators' opening / closing of the injectors 202 may be generated by any applicable control unit, as in this example of the motor control unit 115. 10 The motor control unit 115 thus determines the amount of fuel which should actually be injected at any given time, e.g. based on the radiating operating conditions of the vehicle 100.

The injection system shown in Fig. 2 thus consists of one s.k. Common Rail system, which meant that all injectors (and thus combustion chambers) are supplied with fuel from a common fuel line 204 (Common Rail), which by means of a fuel pump 205 is filled with fuel from a fuel tank (not shown) at the same time as the fuel in the rudder 204, also by utilizing the fuel pump 205, pressurized to a certain pressure. The highly pressurized fuel in the common rudder 204 is then injected into the combustion chamber 201 of the internal combustion engine 101 at the opening of the respective injector 202. Several openings / rods of a specific injector can performed during one and the same combustion cycle, thus several injections can be performed during the combustion of a combustion cycle. Furthermore, the usual combustion chamber is provided with a respective pressure sensor 206 for emitting signals of a pressure radiating in the combustion chamber to e.g. the control unit 115. The pressure sensor can e.g. be piezo-based and should be said fast enough that it can emit crank angle-resolved pressure signals, such as e.g. at every 10, every 5 or every crank angle or other applicable range, such as e.g. an oftare.

With the aid of systems of the type shown in Fig. 2 can the combustion during a combustion cycle in a combustion chambers are controlled to a large extent, e.g. by utilizing multiple injections, where injection times and / or duration can be regulated, and where data from e.g. the pressure sensors 206 can be considered at the regulation. By utilizing data from e.g. the pressure sensor, the conditions in the combustion chamber can be evaluated, whereby water-based liquid can be supplied 11 farbranningen e.g. depending on an estimate of specific heat capacity as below. Concerning the supply of aqueous liquid according to the invention, each combustion chamber comprises, or only a part of, the combustion chamber of the combustion engine, an injector 210 through utilization of which liquid can be supplied to the combustion chamber 201 from a tank 211. The liquid in the tank 211 may be arranged to be pressurized, alternatively a pump (not shown) between tank 211 and injector 210 may be used for pressurization of liquid fir injection to combustion chambers 201.

Injection of liquid according to the present invention exemplified in Fig. 3 by an exemplary method 300, where injection is based on an estimation of a specific heat capacity in the combustion chamber, and there the procedure according to the present example are arranged to be performed by the motor control unit 115 shown in Figs. 1A-B.

Control systems in modern vehicles generally consist of a communication bus system consisting of one or more communication buses to connect a number electronic control units (ECUs) such as the control unit, or controller, 115, and various components arranged on the vehicle. As such, such control systems may include a large number of control units, and the responsibility for a specific function may be divided into more than one control unit.

For the sake of simplicity, Figs. 1A-B show only the motor control unit 115 in which the present invention is implemented in the embodiment shown. However, the invention can also be implemented in a present invention dedicated control unit, or in whole or in part in one or more other control units already existing at the vehicle. Ned thought no the rate at which calculations according to the present 12 When the invention is carried out, the invention can be arranged to be implemented in a control unit which is specially adapted for real-time calculations of the type as below. Implementation of the present invention has shown that e.g. ASIC and FPGA lasings are lit for, and choices can handle, calculations according to the present invention.

The control unit 115 (or the control unit (s) at which present invention is implemented) function according to the present invention may, in addition to depend on sensor signals from the pressure sensor 206, e.g. hero of signals from other controllers or sensors. In general, control units of the type shown are normally arranged to receive sensor signals from different parts of the vehicle, as well as from different control units arranged on the vehicle.

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

The computer program is usually part of one computer program product, wherein the computer program product comprises an applicable storage medium 121 (see Fig. 1B) with the computer program stored on said storage medium 121. The computer program may be non-volatile stored on said storage medium. Said digital storage medium 121 may e.g. consists of flags from the group: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc., and be arranged in or in connection with the control unit, wherein the computer program is executed by the control unit. By the instructions of the other computer program can thus be adapted to the behavior of the vehicle in a specific situation. 13 An exemplary control unit (control unit 115) is shown schematically in Fig. 1B, in which case the control unit may in turn comprise a bending unit 120, which may be constituted by e.g. Any suitable type of processor or microcomputer, e.g. a circuit for digital digital signal processing (DSP), a or multiple Field-Programmable Gate Array (FPGA) circuits or one or more circuits with an Application Specific Integrated Circuit (ASIC) function. The recovery unit 120 is connected to a memory unit 121, which provides the bending unit 120 e.g. the stored the program code and / or the stored data recovery unit 120 need to be able to perform calculations. The coverage unit 120 is also arranged to store partial or final results of coverage in the memory unit 121.

Furthermore, the control unit is provided with devices 122, 123, 124, 125 receives and transmits input and output signals, respectively. These input and output signals may contain waveforms, pulses, or other attributes which of the input signals devices 122, 125 may detected as information for processing by the berding unit 120. Devices 123, 124 for transmitting output signals Or arranged to convert conversion results from the output unit 120 to output signals for transmission to other parts of the vehicle control system and / or the components for which signals Or intended. Each and everyone of the connections to the devices for receiving and transmitting input and output signals, respectively, may be constituted by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), and a MOST bus (Media Oriented Systems) Transport), or any other bus configuration; or by one wireless connection. 14 Returning to the process 300 shown in Fig. 3, the process starts in step 301, where it is determined whether the supply of liquid to the combustion chamber 201 according to the invention is to be carried out. The inventive the regulation can e.g. be arranged to be performed continuously as soon as the internal combustion engine 101 is started. According to one embodiment, injection of liquid into a combustion chamber is performed only if a combustion of fuel takes place during the same combustion cycle.

The process of the present invention thus consists of a method for supplying a liquid constituent water or which is at least water-based to the combustion chamber of the combustion engine 101 while combustion takes place in said combustion chamber 201 in combustion cycles. Vatskan can e.g. consists of an additive for the reduction of a or several substances resulting from the combustion, such as e.g. nitrous oxide, NON. As Or edge Or the term combustion cycle defined as the steps a combustion at an internal combustion engine includes, such as e.g. two-stroke engine two-stroke engine respectively the four strokes of the four-stroke engine. The term includes oven cycles no fuel is actually injected, but where the combustion engine spirit is driven at a certain speed, as by the vehicle's drive wheel via the driveline at e.g. relaxation. Ie. even if no injection of fuel is carried out, a combustion cycle still takes place for example every two vary (for four-stroke engine), or e.g. each vary (two-stroke engine), which rotates the output shaft of the internal combustion engine. The same applies to other types of internal combustion engines.

In step 302, it is determined whether a combustion cycle has or will be paborjas, and when said Or the case continuesOtter the process to step 303, where it is determined whether specific heat capacity is to be estimated. If did not say Or the case returns the procedure to step 302. When specific heat capacity is to be estimated, the procedure proceeds to step 303. As has been mentioned, this estimation can e.g. be arranged to be performed only if combustion is to be performed during the combustion cycle.

According to the present example, the specific is estimated the heat capacity ratio, ie. gamma men sasom it can be realized that other estimation can be performed, such as e.g. only isobar specific heat capacity Cp or isocore specific heat capacity CV, alternatively other applicable conditions between them.

In step 303, the amount of substance n is estimated for the combustion air supplied during the current combustion cycle. This can e.g. performed essentially immediately after the one or more the intake valves have been closed, and a good estimation can obtained through the use of the general gas law, ie. pV nRT (1) The amount of substance n can thus be expressed as: (2) V, i.e. the volume of the combustion chamber, can advantageously be tabulated in the memory of the control system as a function of crank angle or alternatively calculated in an appropriate manner.

The pressure p is the pressure in the combustion chamber 201, which determined with the pressure sensor 206.

R constitutes the general gas constant, and 16 T is the temperature of the combustion gas, which with good approximation can be estimated as the temperature of the inlet temperature, which is usually determined with existing temperature sensors, and which varies slowly and needs can usually be considered constant for a plurality in each other following combustion cycles. This temperature can be suedes determined pA as usual with a conventional inlet temperature sensor.

The procedure then proceeds to step 304, where it is fixed whether the combustion cycle has at night a crank angle position T1 father which gamma y is to be determined. Gamma y may be arranged to be fixed continuously, but it may also be the case that determination of gamma y is carried out first when e.g. the compression step has been completed or substantially has completed, ie. at or around avre dOdpunkt TDC father one piston engine. For example. the estimation of gamma y can be arranged to be performed at the earliest when the piston is mom e.g. 1-20 crank angle degrees from TDC and on its way to this point. The reason for this is that the injection of liquid pAbarjas only late during the compression step, or not forrOn during the expansion phase, in order to obtain a feranglement which contributes to the propulsion of the vehicle, i.e. The transportation takes place at least mainly during the expansion phase.

It is thus established that the crank angle position T1 has After that, the procedure proceeds to step 305, where erasing pressure p at desired crank angle position fixed011s. The pressure in the combustion chamber can be determined substantially continuously during the combustion cycle by using the pressure sensor 206, as at applicable intervals, e.g. every 0.1- weave angle degrees. 17 The process then proceeds to step 306, where the average temperature of the combustion chamber is calculated via general the gas law as T = —pV, where V is crank angle dependent, and ddr p nR determined in step 305. Other parameters as above. Ndr the temperature has been calculated, the procedure continues to step 307.

In step 307, gamma y is then calculated by calculating specific heat capacity at constant pressure C and at constant volume C, respectively.

These heating capacities are tabulated for different chemicals the substances and basic substances in tables issued by NASA, and Or interpolated as a function of temperature, where the temperature determined in step 306 is used. General Or the specific heat capacity at constant pressure C. tabulated on the form: c (T) = alT -2 + a 2 T -1 + a3 + a4T ± as T2 + a6T3 + ct7T4 (3) The specific heat capacity for constant volume, Cv, can then berdknas as CC-R, whereby suedes gamma y can berdknas. If gamma y has been exposed, then in step 308 liquid injection can, if necessary, be performed as below as function of gamma y.

When calculating gamma y, consideration should be given to the case in which EGRA feedback is performed, ie. Some of the exhaust gases from Iran combustion are returned to the inlet side of the internal combustion engine, which affects the chemical composition of the combustion chamber. Regulation of the EGR Feedback constitutes normally a separate regulation, but as described below, it can be advantageous to adapt the EGR Feedback based on the amount of liquid supplied. If EGR feedback can be applied 18 for example The following relationship is applied to estimate specific heat capacity at constant pressure for EGR-aterford gas, where a and b are the number of carbon atoms and hydrogen atoms in the industry, respectively. which is used for propulsion of the vehicle, ie. Cyb, and dar constitutes the lambda value: aCpc 02 + 7CpH 2 O + (a) aA91-1) CpO 2 + 3,773 / 1.0 cpN 2) CpEGRb a + 7 + (4,773 / 19 / —1) (a + 7b) The corresponding calculation of specific heat capacity at constant volume for clean air is based on: 1 / C A = —4.7730.773c (T) + (T)) p IRp ,. 2- , 2 In order to obtain a correct gamma-ray value, they are weighted respectively heat capacity according to eq. (6), where EGR% is the EGR content: Cp = CpAIR * (1 - EGR%) + CpEGR * EGR% (6) The EGR content can e.g. determined as an EGR content determined in a previous combustion cycle. Alternatively, the EGR the content is determined via e.g. emission calculations, where e.g. Carbon dioxide calculations can be used to determine the proportion of combustion air that is made up of recycled exhaust gases. For example. this can be done by feeding the carbon dioxide content at the inlet to the combustion chamber or at combustion chamber outlet or longer downstream in the finishing system, whereby the EGR content can be calculated on a per se skilled edge. The EGR feed thus yields a variable which is not calculated specifically for each combustion cycle, but which is normally available in the vehicle's steering system, where this is calculated with applicable interval. In general, the regulation of EGR feedback applies 19 is much slower than the control of the present invention.

In step 307 an initial value of gamma y is determined, whereby in step 308 the amount of liquid for injection can be carried out. based on established gamma y associated with or without combustion (industry supply).

The determination of the amount of liquid for injection can be performed in different ways, and e.g. is derived from a comparison between the obtained estimation of gamma y and a expected / desired value for gamma y. estimated gamma y is lower than onskvart can one The amount of liquid for injection into the combustion chamber is determined as a function of the difference between the desired value and the obtained value. According to one embodiment, the injection is performed by any applicable amount of liquid, where this amount may be fixed in advance. For example. can an unwanted gamma y curve is stored in the vehicle's control system, where this curve represents the gamma y evolution as a function of crank angle during the combustion cycle that is sought.

This curve can e.g. consists of one during the combustion cycle realistically achieves maxniva far gamma y at current load and radiating speed, and can advantageously be determined in advance, e.g. by applicable calculations and / or feeds on the motor type, whereby this data can be stored in the control system memory with different curves as a function of e.g. speed and load. For example. gamma y can be developed to represent one in any man optimal efficiency. In general, a maximization of gamma y Or onvvard, cid the internal combustion engine efficiency Or dependent on gamma y approximately according to: 1— r 1ddr r represents the compression ratio.

Thus, an increase in gamma y will result in an increase (ie improvement) in efficiency.

Fig. 4 shows a schematic example of the variation gamma y frdn ca. TDC during a combustion cycle.

Referring to Fig. 3, in step 309, injection of liquid is then performed, the process proceeding to step 310 to determine whether a new estimation of gamma y is to be performed, whereby, if so, the procedure returns to step 305 for new pressure determination and new estimation of gamma y. This can continue until e.g. the combustion cycle is completed and the exhaust valves are opened, or until for some other reason it is no longer desirable to inject liquid, such as e.g. due to saving temperature or other reason, whereby the procedure proceeds to step 301 in vnntan pd injection during subsequent combustion cycle.

Thus, the supply of liquid can be continuously regulated based on estimates of y, so that the estimation of gamma y can be arranged to be performed continuously during residual combustion cycle, in which case liquid can be injected into purpose of regulating gamma y against Onskat vdrde. The present invention thus provides an effective way of controlling the combustion of an internal combustion engine.

The injection of liquid has a cooling effect, pd due to the energy that contributes to the displacement of the fluid.

In addition, a dissociation effect occurs when water molecules in gaseous form are divided into hydrogen and oxygen, respectively, where energy acts for the molecular division. 21 Specific heat capacity, and clamed gamma y, can thus be regulated by influencing specific heat capacity by adding liquid, in the present example water, to the combustion chamber. This can be done by following calculation: Cp with water (T) = cp (T) * (1 - water content) + Cp for H (T) * water content (7) , old / .Cp for f1 (T) is a bachelor and is tabulated. In that case, another liquid to water supply, specific heat capacity can be tabulated for this liquid, alternatively specific heat capacity is determined in the corresponding way that has described forEGR above by knowledge of the composition of the additive.

Gamma y can then be determined as: Y = Cp with water ICy with water (8) , dar: Cv with water = Cp with waterR (9) In total, a decrease in the temperature in the combustion chamber thus occurs, which raises the gamma y according to the above equations, which in turn raises the combustion engine. efficiency.

By utilizing the present invention, e.g. actual deviations from in any man Unwanted "optimal" combustion is compensated by utilizing the injection of liquid. For example. industry injectors can wear out over time, whereby injected industry quantity does not accurately correspond to desired 22 industry length, with deviations from Unwanted / Expected combustion as a result.

Furthermore, e.g. the heat value or other properties it has industry that is actually used deviates from the fuel that used in the calculation of the applicable amount for injection, which e.g. may be produced during the internal combustion engine manufacturing process. The composition of the industry can also vary over seasons, e.g. in countries with temperature differences between winter and summer. Thus, the same amount of industry can provide give rise to different results depending on the industry actually used Oven am injected mangd Or the same.

The present invention can be used to compensate for such effects by regulating gamma y and clamed obtain a more favorable / unwanted combustion.

Furthermore, the injection of fluid with star is likely to come to take place at the same time as combustion in the combustion chamber pays off. In the event that combustion occurs at the same time as water injection, consideration must be given to the effect of combustion on gamma y. performed by adding the temperature rise the combustion gives rise to, whereby the effect of the temperature rise caused by the combustion on gamma y is taken into account when calculating Cp and Cv, respectively.

In general, the temperature is higher in the part of the combustion chamber where combustion occurs, and the combustion chamber can be considered as consisting of two zones, where combustion takes place in one zone, with high temperature in this zone as follows, while no combustion, with lower resulting temperature, takes place in the other zone.

Overall, thus obtained at habit ogonblick one average temperature in the combustion chamber which is less than 23 the temperature of the incineration ddr incineration pAgAr. In order to be able to carry out the desired determination of the combustion temperature, knowledge of the heat release during combustion is also required.

This can be determined in different ways, and according to one Embodiments of the present invention use pressure signals The pressure sensor 206 can be used to calculate the heat release during combustion.

The heat release during combustion can be expressed as: dQ1 = pdV + Vdp + dQHT (10) Ddr dQ Or released vdrme, p, V is determined as above and ddr dV constitutes the volume change of the combustion chamber.

V (v), i.e. The volume of the combustion chamber as a function of crank angle can, as above, be tabulated in the control system dV memory or berdknas pd tillmligt sdtt, whereby Oven dço can be fixed. dp is the pressure change in the combustion chamber, which is determined by the pressure sensor 206. d0 / 7, represents the heat released during combustion, which can be determined in such a way that there is vd1 described in it known technology of, for example, Woschni. In this case, the male can also be taken for black body radiation in the combustion chamber in a known manner.

Furthermore, in the Swedish patent application 1350510-2, with the title "PROCEDURE AND SYSTEM FOR CONTROLLING AN COMBUSTION ENGINE 24 IV "describes a method for estimating released heat during an ongoing combustion. The method shown in this application can be applied according to the present invention. Furthermore, the method shown in said application can be applied. then no estimation of the pressure according to the present embodiment is required, without pressure signals from the pressure sensor 206 can be applied during the current firing cycle.

According to the present example, however, the heat release can be estimated according to eq. (10) by utilizing signals from pressure sensor 206.

The pressure change p as a function of crank angle degree T in a cylinder (combustion chamber) for a combustion cycle can, as above, be obtained by utilizing the sensor signals from the pressure sensor 206. Furthermore, by utilizing fixed pressure, the temperature for that part of the combustion chamber where no combustion takes place is estimated by utilizing estimated pressure and by utilizing eq. (11), since the temperature of the part of the combustion chamber where no combustion takes place is expressed as: Tn_pi = Tn K-1 P n + 1 , where Tno can be the corresponding combustion air temperature for for example the time / crank angle position at which the valves are closed after the supply of combustion air as above, or a temperature which has been determined by means of the general gas laws; as above at a time / crank angle position before combustion has paborjats.

Furthermore, n, n + 1, etc. are consecutive times or crank angle positions.

K = 7, whereby also K can be determined as stated for 7 above. By utilizing eq. (11) (alternatively the general gas law before combustion has been started) the temperature for that part of the the combustion chamber where no combustion pagar is determined, where, however, this temperature is affected by ongoing combustion by the effect of the heat release on the pressure, which Reflected in the signals emitted from the pressure sensor, which in turn affects the temperature according to eq. (11). When then one combustion takes place, the heat release will give rise to one temperature increase in the part (s) of the combustion chamber where combustion takes place. This temperature increase, which is added to it according to eq. (11) determined temperature to obtain the combustion temperature, can be calculated from the relationship: dQ / RC pdT (12) , (Jar dQ is the heat release, which can be determined as above. consists of combustion mass (ie fuel + air + EGR that is involved in the combustion), which is also determined as above, C, i.e. specific heat capacity, which can also be calculated as above. dT is the increase in temperature as a phase of the combustion at a given ferrous mass and at a given Cp value.

Thus, by using equ (12), dT and thus AT can determined, the increase generated by the combustion at habitual time / crank angle position can be added to the unburned zone temperature given by eq. (11) to obtain the combustion temperature. This temperature can then be used 26 when calculating specific heat capacity as above, and whereby the calculations can thus be updated as the color burn progresses.

According to one embodiment, injection of liquid is not performed unless the average temperature of the combustion chamber exceeds any applicable temperature TL ,, where this can thus be obtained by means of the general gas laws as above, and which is also described in the Swedish patent application 1350507-8, where it is described in detail how the average temperature in a combustion chamber can be estimated by utilizing among other the pressure in the combustion chamber, which can be obtained with the pressure sensor 206.

According to the procedure shown in the said application, an estimation is performed for the coming time, where, among other things, the pressure is estimated. for the coming part of the combustion cycle. Such estimation can is also applied to the present invention, the estimation thus constituting a prediction, for by estimating predicting the applicable amount of liquid for injection by estimating the pressure, whereby the gamma y can also be estimated, and thus is predicted, for the coming part of the combustion cycle. This also means that gamma y can be estimated for different conceivable liquid injection alternatives before injection actually takes place, whereby then an injection alternative can be selected which is best expected to meet desired result, where gamma y can be calculated according to the above equations and estimated pressure development, ie. the pressure change is also estimated. This is also exemplified in detail in the said application, as well as in the previously mentioned Swedish patent application 1350510-2, where it is described how released heat can be estimated before combustion takes place, and so on the pressure is estimated. As the combustion cycle progresses can then gamma y be re-estimated for the next part of 27 the combustion cycle based on actual radiating pressure when estimation is performed, whereby fly injection can be determined based on estimated gamma y, where also estimation for different alternatives anyo can be performed. Water injection options can e.g. is made up of different combinations of water shortage, time of injection, and length of injection.

Thus gamma y can be estimated for a future part of the combustion cycle, whereby also gamma y for the combustion cycle can be estimated for different injection alternatives, whereby the injection alternatives can evaluated and an injection option can be selected. According to an embodiment of the invention, the injection is performed at least partially during the compression step of the combustion and thus completely or at least partially before the combustion.

Thus, gamma y can be predicted by estimation according to the above equations for the entire combustion process for e.g. different amounts of water injected before the combustion, where the entire combustion is estimated, and where in the estimation the effect of supplied liquid is taken into account through the effect on specific heat capacity. Injection of applicable water shortage can then be performed based on the result of the estimation. Gamma can thus be estimated for the entire upcoming combustion for a number of injection alternatives, where injection alternatives e.g. can be selected based on how the gamma curve is selected respectively injection options follow Undesired gamma curve.

When supplying liquid to the combustion according to the present invention, additional aspects should also be considered. For example. As above, an EGR feed of some of the exhaust gases formed during is normally applied the combustion. The EGR feedback generally has a positive (decreasing) impact on e.g. NOx formation. The supply of liquid according to the present invention will entail one 28 modified exhaust gas tightening composition compared to the case when liquid is not supplied. For example. the liquid as above is partly made up of water, whereby it is also likely that a larger proportion of water will normally occur in the resulting exhaust stream.

This means that a regulation of the EGR Aterforingen based on pi the supply of liquid may be required. For example. it may be necessary to reduce the EGR experience due to a relatively higher water content in the exhaust stream, which gives a better effect with respect to the NOx reduction, but with the risk that undesirably high water content can be obtained in the combustion chamber if the EGR-Atherforingen becomes increasingly heg in relation to water content.

The regulation of the EGR feedback can be performed in any way applied, where e.g. Impact of EGR feedback on it specific heat capacity as above can be taken into account and wherein the EGR feedback e.g. can be regulated based on these calculations. In general, control of the EGR feedback is slow (on the order of seconds) compared to the control performed according to the present invention. calculations are performed during the current combustion cycle and days calculation can be performed on e.g. one hundredth of a second, one thousandth of a second or a shorter time.

There is also a supply of water combustion chamber additional aspects that should be considered.

The pressure in a combustion chamber can amount to relatively high pressures, such as maximum pressures in the order of 200-300 bar. Normally, fuel injection is performed with significantly higher pressure than the combustion chamber pressure, such as e.g. 1500-2500 bar, whereby changes in the combustion chamber pressure become essentially negligible in relation to the high fuel injection pressure. This means that the injected amount of fuel can be determined with good accuracy. Use of 29 However, high pressures are usually associated with high costs, for which reason it may be unwise to perform the injection of liquid at significantly lower pressures, such as e.g. pressure in the same order of magnitude as radiating combustion chamber pressure. This means in turn that for a certain Opening Time has The injection nozzle for injecting liquid can, due to the back pressure of the combustion chamber, be supplied in different amounts for one and the same opening time depending on the radiating combustion chamber pressure. Thus, the injection time of the liquid can be arranged to be controlled based on erasing combustion chamber pressure ddr this e.g. can be determined by using the pressure sensor 206.

Thus, at higher resuscitation combustion chamber pressures, a longer opening time can be used in conjunction with combustion chamber pressure is lower, ddr, as realized, erasing combustion chamber pressure will depend on it crank angle position at which injection of fluid takes place.

Furthermore, the liquid supply may require some protection aspects / measures may need to be taken into account. For example. can it there are limitations with respect to ndr below the combustion cycle the injection of liquid should take place for other reasons. For example. it may be inconvenient for the piston to be at a certain number of crank angle degrees from the upper dead center when injection takes place so as not to be too much of the cylinder cradle must be exposed during the injection with risk for rock hit with flushing out of oil film as a result and associated risk of unwanted wear.

Furthermore, the supply of liquid can e.g. be arranged to be driven by the speed of the vehicle below any particular speed, or am the vehicle becomes stationary, or am off there is another reason for the risk of the internal combustion engine mom card will be stangas ay. In dive-like situations, it can be unfortunate that e.g. the water content in the internal combustion engine system has time to be reduced before the internal combustion engine is switched off to avoid water-associated injuries. According to an embodiment of the invention, the supply of liquid is arranged to be shut off by the speed of the vehicle is less than any applicable speed and the ambient temperature of the vehicle is less than e.g. nail degrees Celsius in order to avoid water remaining in the system after the internal combustion engine has been switched off with the risk of freezing as a fault.

According to one embodiment, gamma is estimated for a combustion cycle, whereby appropriate liquid injection is determined based on this estimation, then injection of liquid is carried out during one or more subsequent combustion cycles. The injection can e.g. occur before and / or during combustion during the subsequent combustion cycle. This procedure can e.g. applied when the conditions for several consecutive combustion cycles Or essentially same.

The invention has been exemplified above in a manner in which a pressure sensor 206 is used to determine a pressure in the combustion chamber, and by means of which temperature and specific heat capacity as above can be estimated. One alternatives to using pressure sensors can instead be made of using one (or more) other sensors, such as e.g. high-resolution ion current sensors, knock sensors or strain gauges, whereby the pressure in the combustion chamber can be modeled by using sensor signals from such sensors. It Or Oven possible to combine different types of sensors, e.g. to obtain a more accurate estimation of the pressure in the combustion chamber, and / or to use others 31 applicable sensors, where the sensor signals are converted to the corresponding pressure for use in control as above.

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

Furthermore, the present invention has been exemplified above in connection with vehicles. However, the invention is also applicable to arbitrary vessels / processes where regulation of specific heat capacity as above is applicable, such as e.g. water- or aircraft with combustion processes as above.

It should also be noted that the system can be modified according to various embodiments of the method according to the invention (and vice versa) and that the present invention is not in any way is limited to the embodiments described above by the method according to the invention, but relates to and includes all embodiments within the scope of protection of the appended independent claims. For example. the invention is applicable to the injection of any liquid into the internal combustion engine combustion chamber, as long as this liquid at least partly, or mainly, contains water.

Claims (37)

A method of controlling an internal combustion engine (101), said combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said combustion chamber (201), wherein combustion in said combustion chamber (201) ) takes place in combustion cycles, the process being characterized by: 1. during a first part of a first combustion cycle, estimating a first mat on a specific heat capacity for said first combustion cycle, 2. based on said first mat, determining a first quantity of a first liquid for supply to said combustion chamber (201), and - to said combustion chamber (201) supply said first quantity of said first liquid. The method of claim 1, further comprising: Using a first sensor means (206), determining a first parameter value representing a quantity with respect to the combustion in said combustion chamber (201), and 2. determine said first mat on a specific heat capacity based on said first parameter value. A method according to claim 1 or 2, wherein said first liquid constitutes a liquid substantially containing water. A method according to any one of claims 1-3, wherein said first liquid is water. A method according to any one of claims 1-4, further comprising supplying said first amount of liquid to 33 said combustion chambers (201) during a part of said first combustion cycle following said first part of said first combustion cycle. A method according to any one of claims 1-5, further comprising: 1. determining a specific heat capacity desired for said subsequent part of said first combustion cycle, 2. comparing the desired specific heat capacity with said estimated first measure on specific heat capacity, and - based on named comparison, determine said first amount of said first water. A method according to claim 6, wherein said desired specific heat capacity is stored in control systems for controlling said internal combustion engine as a dependency on one or more of the group: crank angle position, internal combustion engine load, internal combustion engine speed. The method of claim 6 or 7, further comprising: 1. performing a plurality of estimates of specific heat capacity during said first combustion cycle, and 2. controlling the supply of said first liquid during said first combustion cycle based on said plurality of estimates of specific heat capacity. A method according to any one of claims 6-8, further comprising supplying liquid at a plurality of times during said first combustion cycle. A method according to any one of the preceding claims, wherein said specific heat capacity is a ratio between 34 isobar heat capacitance Cp and isocore heat capacitance C. A method according to any one of the preceding claims, wherein said specific heat capacity is constituted by the heat capacity ratio gamma y, i.e. 2 / = 'or a Cv corresponding ratio. A method according to any one of the preceding claims, wherein said specific heat capacity is estimated for a crank angle position at the earliest constituting a crank angle position a maximum of 20 crank angle degrees prior to an Upper dOd point (TDC). A method according to any one of the preceding claims, wherein exhaust gases are returned to said combustion, further comprising in determining said specific heat capacity estimating a first specific heat capacity for air and a second specific heat capacity for exhaust gases returned to combustion (EGR), wherein said capacity determined based on a weighting of the said first and second specific heat capacity, respectively. A method according to any one of the preceding claims, further comprising: supplying said first liquid at a first time, wherein said first liquid is supplied at said first time or such evaporation of said first liquid substantially occurs following a compression phase for said first combustion. A method according to any one of the preceding claims, further comprising: supplying said first liquid at a first time during said first combustion cycle, wherein supplying said first liquid at said first time is such that said liquid is at least partially compressed for at least combustion cycle. A method according to any one of the preceding claims, further comprising: supplying said first liquid at a first time during said first combustion cycle, the supply of said first liquid at said first time being such that said liquid is at least partially supplied to combustion cycle. A method according to any one of the preceding claims, further comprising: - in said determining said first amount of said first liquid for supply to said combustion chamber (201), estimating an expected specific heat capacity for at least two alternatives for supplying said water part of said combustion cycle, wherein said alternative for supplying liquid comprises alternatives relating to at least one of the amount of liquid, time of supply, liquid pressure at supply, the time the supply takes. A method according to any preceding claim, wherein said specific heat capacity is an estimate of an expected specific heat capacity for said subsequent portion of said first combustion cycle. 36 The method of claim 18, further comprising estimating said expected specific heat capacity for said subsequent portion of said first combustion cycle, by estimating the pressure change in said combustion chamber during said subsequent portion of said first combustion cycle. The method of claim 19, wherein said pressure change is estimated based on an estimated heat release during combustion during said first combustion cycle. A method according to any one of the preceding claims, further comprising: - evaluating at least one first and a second alternative for supplying liquid during said subsequent part of the first said combustion cycle, wherein of said first and second alternatives for supplying liquid as in most extent expected to result in the desired specific heat capacity selected. A method according to any one of the preceding claims, wherein the supply of liquid is carried out in at least two cases during said subsequent part of said combustion cycle, said second supply being determined after said first supply of liquid has been carried out. A method according to any one of the preceding claims, further comprising that in estimating specific heat capacity after supply of liquid has been carried out, in said estimating consideration is given to said supply of said first liquid. 37 A method according to any one of the preceding claims, further comprising estimating said first mat on a specific heat capacity for said first combustion cycle based on a pressure radiating in said combustion chamber (201). A method according to any one of the preceding claims, further comprising: - estimating said first mat on a specific heat capacity at least in part based on an estimated combustion temperature. The method of claim 25, further comprising estimating said combustion temperature as a sum of an estimation of a temperature increase caused by combustion in relation to a first temperature, and an estimation of said first temperature, wherein said first temperature constitutes an estimated temperature for of combustion. gas in the said combustion chamber. A method according to any one of the preceding claims, further comprising supplying said first liquid to a subsequent combustion cycle following said first combustion cycle. The method of any of the hazardous claims, further comprising determining the amount of liquid to be supplied individually for each cylinder. A method according to any one of the preceding claims, wherein said control is performed for a plurality of consecutive combustion cycles. 38 A method according to any one of the preceding claims, wherein said liquid is an additive for reducing a substance resulting from said dyeing. A method according to any one of the preceding claims, wherein said liquid constitutes an additive for reducing nitrogen oxides resulting from combustion in said combustion chamber. A computer program comprising program code, which if said program code is executed in a computer, causes said computer to perform the procedure according to any of claims 1-31. A computer program product comprising a computer-recordable medium and a computer program according to claim 32, wherein said computer program Or is comprised in said computer-recordable medium. A system for controlling a combustion engine (101), said combustion engine (101) comprising at least one combustion chamber (201) and means (202) for supplying fuel to said combustion chamber (201), combustion taking place in said combustion chamber (201). in combustion cycles, the method being characterized in that the system comprises: - means (115) arranged to estimate during a first part of a first combustion cycle, a first mat on a specific heat capacity for said first combustion cycle, - means (115) arranged to be based on said first mat, determining a first quantity of a first liquid to be supplied to said combustion chamber (201), and means (115, 210) arranged to supply to said combustion chamber (201) said first quantity of said first liquid. 39 A system according to claim 34, characterized in that said combustion engine comprises means for supplying liquid to said combustion chamber independently of fuel supply to said combustion chamber. A system according to claim 34 or 35, characterized in that said internal combustion engine consists of one of the group: vehicle engine, marine engine, industrial engine. Vehicle (100), characterized in that it comprises a system according to any of claims 34-36. FIG. 'IA 13 .--- 104 103? , ---- 108 01 107 101? 106 200 .---- 1 2 /