DE112014003463T5 - Method and system for controlling an internal combustion engine - Google Patents

Abstract

The present invention relates to a method for controlling an internal combustion engine (101), wherein the internal combustion engine (101) comprises at least one combustion chamber (201) and elements (202) for supplying fuel to the combustion chamber (201), wherein the combustion in the combustion chamber ( 201) takes place in combustion cycles. The method is characterized by: determining a first parameter value during a first combustion cycle and using a first sensor element (406) representing an amount with respect to the combustion chamber (201), using a first parameter value determining a first amount of additive for supplying to the combustion chamber, and - supplying the first amount of additive to the combustion chamber (201). The invention also relates to a system and a vehicle.

Description

Field of the invention

The present invention relates to internal combustion engines, and more particularly to a method of controlling an internal combustion engine according to the preamble of claim 1. The invention also relates to a system and a vehicle and to a computer program product implementing the method of the invention.

Background of the invention

The following description of the background of the invention is a description of the background of the invention, and therefore does not necessarily depict the state of the art.

In conjunction with increased concern among governments for pollution and air quality, emissions standards and regulations have been drafted for internal combustion engine emissions in many jurisdictions.

Such emissions regulations often consist of requirements that define acceptable exhaust emission limits for vehicles equipped with internal combustion engines. For example, levels of nitrogen oxides (NO _x ), hydrocarbons (HC) and carbon monoxide (CO) are often regulated. These emission regulations may also concern the occurrence of particulate matter in exhaust emissions.

In an effort to comply with these emission regulations, the exhaust gases caused by the combustion of internal combustion engines are treated (purified). For example, a so-called catalytic purification process can be used, so that exhaust treatment systems in z. As vehicles and other vehicles usually include one or more catalysts and / or other components. For example, the exhaust treatment systems in diesel engine vehicles often include particulate filters.

Catalysts of internal combustion engines may include several different types, and may require different types for different fuels and / or the conversion of different undesirable substances / compounds present in the exhaust gas stream. In proportion to at least nitrous gases (nitrogen monoxide, nitrogen dioxide), hereinafter referred to as nitrogen oxides NO _x , heavy trucks often include a catalyst in which an additive is supplied to the exhaust gas stream resulting from combustion in the internal combustion engine to mainly increase nitrogen oxides NO _x To reduce nitrogen gas and water vapor.

This reduction of emissions of nitrogen oxides from diesel engines is usually carried out by a so-called SCR (Selective Catalytic Reduction) method. As a result of this process, an additive, usually an aqueous solution comprising the substance urea, is supplied in an appropriate dose to the exhaust gas stream upstream of an SCR catalyst.

The function of the SCR catalyst usually requires access to ammonia (NH ₃ ), where e.g. For example, in the evaporation of urea, ammonia is also formed so that ammonia subsequently reacts with nitrogen oxides in the exhaust gas stream in the SCR catalyst, resulting in conversion into nitrogen gas and water vapor.

Brief description of the invention

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

• – Bestimmen eines ersten Parameterwerts während eines ersten Verbrennungszyklus und unter Verwendung eines ersten Sensorelements, der eine Menge in Bezug auf die Brennkammer darstellt,
• – unter Verwendung des ersten Parameterwerts Bestimmen einer ersten Menge an Zusatz zum Zuführen zu der Brennkammer, und
• – Zuführen der ersten Menge an Zusatz zu der Brennkammer.

The present invention relates to a method for controlling an internal combustion engine, wherein the internal combustion engine comprises at least one combustion chamber and elements for supplying fuel to the combustion chamber, the combustion taking place in the combustion chamber during combustion cycles. The method is characterized by:

• Determining a first parameter value during a first combustion cycle and using a first sensor element representing an amount with respect to the combustion chamber,
• Using the first parameter value, determining a first amount of additive for supplying to the combustion chamber, and
• - supplying the first amount of additive to the combustion chamber.

The addition can z. B. consist of an additive for the reduction of nitrogen oxides, resulting from the combustion in the combustion chamber. During combustion in internal combustion engines, particularly in diesel engines, undesirable nitrogen oxides NO _x are generated at least in part due to excess oxygen, which is generally used in combustion in diesel engines. Alternatively, the additive may be provided to reduce another combustion-resultant substance / compound. Substances / compounds will be referred to hereinafter only by using the term "substance", which is thus considered to include chemical compounds, compositions and substances.

As mentioned, due z. For example, government regulations often require some types of treatment of the exhaust stream with the aim of reducing the amount of nitrogen oxides in the exhaust stream before exhaust flow into the environment of the vehicle, which reduction of emissions by injecting additives in an appropriate dose can be performed in the exhaust stream upstream of an SCR catalyst.

The additive then vaporizes upon contact with the hot exhaust gases, thereby generating / releasing ammonia to subsequently reduce nitrogen oxides in the exhaust gases into nitrogen gas and water vapor in the SCR catalyst.

The additive may be supplied by means of an injection system comprising one or more nozzles for injecting the additive into the exhaust stream. With the correct dosage of additive, the emission of nitrogen oxides can be greatly reduced.

However, the desired function of injection of additives is dependent on the exhaust gases maintaining a high enough temperature for the additive to evaporate. During large portions of the operating mode of a diesel engine, the exhaust gases usually maintain a high enough temperature for the desired evaporation to occur.

However, there are situations where this can not be guaranteed, and it may be difficult, at least in some modes of operation, to avoid having some of the injected additive, e.g. As a urea / aqueous solution with wall surfaces of z. B. one or more exhaust pipes, catalysts, silencers in a non-evaporated state comes into contact. In such situations, urea / urea based compounds may adhere to wall surfaces in the exhaust system.

If the formation of solid formations is greater than the vaporization of the formed coating, accumulation of deposits will progressively occur under unfavorable conditions, the result may be a significant accumulation of solids. These accumulations may become so large that the performance of the internal combustion engine is adversely affected, because the exhaust gas flow in the exhaust system is affected (throttled), and in case of large accumulation of accumulation, the continued operation of the engine can be completely prevented in extreme cases. The deposit can also damage components in the aftertreatment system when the generated formations e.g. B. in the form of lumps from the location where they were formed, and then in the exhaust stream z. B. to a subsequent SCR catalyst or other components are carried. The formation of the deposit can also lead to a reduced exhaust gas purification function.

According to the present invention, such problems with the formation of deposits can be reduced. Similarly, the need for SCR catalysts can be reduced or eliminated altogether. In addition, the use of additives can be adapted to the prevailing requirements, so that an excessive supply of additives with the associated costs can be reduced.

According to the invention, the additive is injected directly into the combustion chamber of the internal combustion engine. This can be z. Example, be achieved by the use of an arranged in direct connection with the combustion chamber injection element, wherein the injection of additive can be performed after the inlet for supplying the combustion gas was closed. The temperature in the combustion chamber is substantially higher than, for example, at least during the combustion of fuel. In the SCR catalyst, where the exhaust stream is subsequently cooled as it passes through the exhaust pipe, since, among other things, the exhaust pipe is usually cooled by the ambient air. The SCR catalyst is required inter alia for this cooling, otherwise the reaction rate during the reduction of NO _x with the use of the additive would be too low for the execution of the desired reduction, before the exhaust gas flow is released into the environment of the vehicle.

On the other hand, in the combustion chamber of the internal combustion engine, the temperature is usually so high that the desired reaction rate could be achieved without a catalyst, and by injecting additive directly into the combustion chamber, a very high reaction rate can be obtained in the reduction of the resulting nitrogen oxides, since the exhaust gas temperature still high.

According to a preferred embodiment of the present invention, the nitrogen oxides resulting from the combustion are estimated so that a suitable amount of additive can be injected depending on the estimated amount of resulting nitrogen oxides. The estimate can z. B. may be performed during a combustion cycle, wherein the amount of injected additive in subsequent combustion cycles can be controlled based on the estimated amount of nitrogen oxides.

If the applicable amount of additives is to be injected, then the known chemical conditions may be applied during the reaction between the additive and the nitrogen oxides to determine the applicable amount of additive for delivery to the combustion chamber. In this determination, the temperature of the combustion chamber can also be estimated, for. B. using the first parameter value, wherein the amount of additives z. B. may be dependent on the expected reaction rate.

According to one embodiment, a part of the required additive may be arranged to be injected into the combustion chamber, while another part may be injected in a conventional manner downstream of the internal combustion engine, wherein a part of the reduction in the combustion chamber may be carried out and a part z. B. can be performed in an SCR catalyst. According to one embodiment, no external injection element arranged in the exhaust pipe is required for supplying additive, but instead additive is supplied via the combustion chamber of the internal combustion engine, in order, for. B. to be transported to a catalyst such as the SCR catalyst. Additives supplied to the combustion chamber according to this embodiment may thus be used partly for reduction in the combustion chamber, and partly for reduction in a subsequent catalyst, or only for use in a subsequent catalyst.

Furthermore, the estimation of the amount of nitrogen oxides resulting from the combustion, for. B. be configured to be executed at applicable times, such. B. every time a significant change in combustion occurs, for. B. at a change in the injected amount of fuel. For example, the injection may be performed during one or a suitable number of combustion cycles, such that the injection of additive may be subsequently performed based on the estimate, eg. As long as the conditions remain the same or substantially the same.

According to one embodiment, the amount of resulting nitrogen oxides is estimated for each combustion cycle and during the ongoing combustion cycle, wherein the supply of additives during each combustion cycle can be adapted to the combustion of the ongoing combustion cycle during the ongoing combustion cycle, and also injected during the expiring combustion cycle.

According to a preferred embodiment of the present invention, the supply of additive is carried out at an early stage during the combustion cycle. For example, the supply of additive may be arranged to be carried out in whole or in part before the combustion of fuel is initiated or terminated, e.g. B. completely or partially before the fuel injection is initiated or terminated. The injection of additive may also be arranged to be carried out in whole or in part before the maximum pressure and / or temperature has been reached during the combustion cycle.

According to one embodiment, the supply of additives is carried out or at least initiated before the piston has reached top dead center in a piston engine. According to one embodiment, the supply of additive is at least partially carried out after one or more intake valves of the internal combustion engine have been closed for the admission of combustion gas.

Furthermore, the supply of additives may be arranged to be performed only when the temperature in the combustion chamber satisfies an applicable condition. For example, the supply may be arranged to be executed only once a certain temperature is reached in the combustion chamber has been. Furthermore, the supply may be arranged to be executed only when the temperature of the combustion chamber falls below an applicable temperature. If the temperature of the combustion chamber is too high, there may be a risk that the added additive is oxidized, with the result that the amount of the first substance produced during the combustion, for. As the amount of nitrogen oxides, may be greater than it would have been without the supply of an additive. Furthermore, temperature limits and / or the amount of additive for feeding in the supply of additive can be set to z. B. to be dependent on the prevailing air / fuel ratio. The greater the prevailing air lock, ie the higher the prevailing lambda value, the more the risk of oxidation of the additive decreases. Thus, a higher combustor temperature during combustion may be allowable with a first higher lambda value compared to combustion at a second lambda value, which is lower compared to the first lambda value.

The supply of additive may also be arranged to be dependent on the prevailing engine load, which supply may be arranged to operate before / during combustion, e.g. B to be performed only up to a certain engine load, with the aim of avoiding that additive is supplied at too high temperatures. Thus, the addition of makeup prior to combustion may benefit from the lower temperatures that generally occur at lower loads.

According to one embodiment, the impact on the supply by a first amount of supplement, whether delivered early or late during the combustion cycle, may be estimated before the supply is actually executed such that the designed / intended amount of additive for delivery is based can be corrected to the expected effect before the feed is actually executed, e.g. In relation to the amount of the first substance produced.

Thus, a first measure of at least one first substance resulting from combustion during a first combustion cycle may be estimated so that a first amount of additive for delivery to the combustion chamber may be determined and a second measure of the at least one first substance can be estimated from the expected resulting amount of the first substance in the supply of the first amount of additives before the supply is actually carried out, and so that the first amount of additive for supplying to the combustion chamber can be corrected based on the second measure.

Furthermore, the measure of the at least one first substance can be estimated iteratively, and the first amount of additives can be iteratively corrected based on certain measures, until a measure of at least one first substance z. B. meets a first condition.

Similarly, the expected temperature evolution of the combustion chamber may be estimated, so that the supply of additive may be controlled based on the expected temperature evolution.

According to one embodiment, the generated amount of the first substance is estimated during a first combustion cycle so that the additive is supplied during a subsequent second combustion cycle, wherein the supply according to the above may be performed before / during / after the combustion during the subsequent second combustion cycle. Current parameters such. B. currently measured cylinder pressure for a combustion cycle in which the supply has been performed, can thus be used to estimate the generated amount of the first substance, and thus to determine the applicable amount for a subsequent combustion cycle, wherein the additive z. B. can be supplied prior to combustion during the subsequent combustion cycle. A new estimate of the amount of substance produced during the subsequent second combustion cycle may then be made such that the amount of additives can be adjusted again based on this estimate for a further subsequent third combustion cycle, and thus the addition of additive is thus on a cycle cycle Basis can be controlled. This may be particularly advantageous when the injection of additives according to the above takes place early during the combustion cycle.

According to an embodiment, signals of a _NOx sensor arranged downstream of the internal combustion engine, used in the determination of the applicable amount of additive to supply to the combustor. In this case, z. For example, an undesirably high NO _x level indicated by the NO _x sensor will result in an increase in the amount of reductant supplied.

According to one embodiment, the prevailing in the combustion chamber temperature is also estimated / used, so that the injection of additive z. B. may be configured to be executed only when the temperature of the combustion chamber exceeds an applicable temperature. This has the Advantage that the formation of unwanted deposits in / downstream of the combustion chamber, which are caused by the addition, can be largely avoided.

According to one embodiment of the invention, additional fuel injection is performed prior to or concurrently with the injection of additive so that the temperature in the combustion chamber may be increased through the use of the additional fuel injection so as to facilitate desired chemical reactions.

According to one embodiment of the invention, the invention is combined with the regulation of the combustion of the internal combustion engine during a running combustion cycle, wherein the combustion in the direction of an applicable criterion such. G., One or more of: resulting nitrogen oxides, combustion temperature, pressure amplitude, and / or rate of pressure change, heat losses, work generated in the combustion, can be regulated.

The injection of additive may also be arranged to be performed individually for each cylinder, i. H. Resulting nitrogen oxides can be estimated individually for each combustion chamber, so that the injection of additive can be adjusted individually for each combustion chamber.

The invention thus facilitates a regulation or regulation in which z. B. Differences between different cylinders detected, and nitrogen oxide fluctuations by using individual adjustment of the injected amount of additive for each combustion chamber can be compensated. It may also be the case that injecting different amounts of additive into different combustion chambers is desirable, e.g. To control certain cylinders in the direction of meeting a criterion, and other cylinders towards another applicable criterion, which can also be achieved according to the invention. Furthermore, only one or only some of the cylinders may be arranged to be controlled according to the invention, while the combustion in the remaining cylinders may be carried out in a conventional or other applicable manner.

The method according to the present invention may e.g. By using one or more processors, one or more field programmable gate array (FPGA) circuits, and / or one or more application-specific integrated circuits (ASIC).

Further features of the present invention, as well as related advantages, are described in the detailed description of the exemplary embodiments shown below and in the accompanying drawings.

Brief description of the drawings

1A shows a schematic representation of a vehicle in which the present invention can be used.

1B provides a control device in the control system for the in 1A represented vehicle.

2 provides the aftertreatment system for the in 1 displayed vehicle in more detail.

3 FIG. 10 illustrates an example of a metering system for the delivery of additives to the exhaust gas stream.

4 puts the combustion engine in the in 1A shown vehicle in more detail.

5 illustrates an exemplary method according to the present invention.

6 illustrates an example of temperature tracking, nitrogen oxide change, and heat output for combustion.

7 FIG. 10 illustrates an example of pressure tracking in a combustor wherein injection of additives is performed prior to combustion.

Detailed description of the embodiments

1A shows a schematic representation of a drive train in a vehicle 100 according to an embodiment of the present invention. The powertrain includes a motor 101 in the usual way via an output shaft to the internal combustion engine 101 usually via a flywheel 102 , via a clutch 106 with a gear 103 connected is.

The internal combustion engine 101 is controlled by the control system of the engine via a control device 115 controlled. Similarly, the clutch 106 , which may consist of an automatically controlled clutch, as well as the transmission 103 controlled by the control system of the vehicle by means of one or more applicable control devices (not shown). Of course, the drive train of the vehicle can also be of a different kind, such. B. with an automatic transmission, or a kind with a manual transmission, etc.

An output shaft 107 from the transmission 103 drives the drive wheels 113 . 114 in the usual way via the final gear and the drive shafts 104 . 105 at. In 1A is just a shaft with drive wheels 113 . 114 illustrated, but the vehicle may usually include more than one equipped with drive wheels shaft or one or more additional waves, such. B. one or more carrier waves. The vehicle 100 also includes an exhaust system with an aftertreatment system 200 for the usual treatment (purification) of exhaust emissions resulting from combustion in the combustion chamber (eg cylinders) of the internal combustion engine 101 result.

The aftertreatment system is in 2 shown in more detail. The figure represents the internal combustion engine 101 of the vehicle 100 which consists of an engine with turbo, which is why the exhaust gas generated by the combustion (the exhaust gas flow) via a turbocharger 220 to be led. Alternatively, the turbocharger z. B. correspond to a composite type. The function of different types of turbochargers is well known, and therefore will not be described in detail herein.

The exhaust gas flow is subsequently via a pipe 204 (indicated by arrows) to a diesel particulate filter (DPF) 202 via a diesel oxidation catalyst (DOC) 205 directed. During combustion in the internal combustion engine, soot particles are formed, and the particulate filter 202 is used to collect these soot particles. The exhaust stream is passed through a filter structure in which soot particles are captured by the passing exhaust stream and stored in the particulate filter.

The oxidation catalyst DOC 205 has several functions, and is normally used mainly in aftertreatment to oxidize residual hydrocarbons and carbon monoxide in the exhaust stream into carbon dioxide and water. The oxidation catalyst 205 can also oxidize a large fraction of the nitrogen oxides (NO) occurring in the exhaust stream into nitrogen dioxide (NO ₂ ). Oxidation of nitric oxide NO in nitrogen dioxide NO ₂ is advantageous in the reduction of nitrogen oxides NO _x . As mentioned above, usually a SCR (Selective Catalytic Reduction) catalyst 201 used for this purpose using ammonia (NH ₃ ), or a composition from which ammonia can be generated / formed, e.g. As urea, as an additive for the reduction of nitrogen oxides NO _x in the exhaust stream. However, the efficiency of this reduction is influenced by the ratio between NO and NO ₂ in the exhaust stream, so that the reduction reaction in a positive direction is affected by the previous oxidation of NO to NO ₂ .

With respect to the present invention, the aftertreatment system can generally be of different types, and must e.g. B. no particle filter 202 or oxidation catalyst 205 include. According to a preferred embodiment, no SCR catalyst is required because the reduction of nitrogen oxides can be carried out completely in the combustion chamber of the internal combustion engine. The aftertreatment system may also include additional, non-displayed components.

For the SCR catalyst thus an addition to the reduction of the concentration of nitrogen oxides in exhaust gases is required. This addition is often urea-based and can, for. B. consist of the product AdBlue, which consists essentially of urea, which is diluted with water.

An example of a conventional system for the supply of additive is in 3 shown in more detail, where of the above-mentioned components, only the particulate filter 202 and the SCR catalyst 201 and the system except the catalyst 201 a urea tank 302 comprising the urea dosing system (UDS) 303 connected is.

The urea dosing system 303 includes a UDS control device 304 or is controlled by it, the control signals for controlling the supply of additive generated, so that the desired amount of the urea tank 302 using an injector 305 upstream of the SCR catalyst 201 is injected into the exhaust stream, resulting from the combustion in the cylinders of the internal combustion engine 101 results. 3 also provides a NO _x sensor 308 which is downstream of the SCR catalyst 201 is arranged.

The more specific functions of urea dosing systems are well described in the art, and the precise method of injection of additives will therefore not be described in further detail herein. In general, however, the temperature at the injection site / SCR catalyst should be 201 at least 200-250 ° C, preferably above 300 ° C, so that the desired reaction rates, and thus the desired reduction of the first compound, such as. As one or more types of nitrogen oxides is achieved.

However, according to the above, such systems are associated with certain disadvantages. If z. For example, if the temperature at the position in the aftertreatment system where the addition of additive occurs is too low, there is a risk that with the injector 305 Injected urea, instead of evaporating directly as a result of passing exhaust gas flow, impinges on relatively low temperature tube walls, causing the additive to adhere and begin the accumulation of crystals. As long as the vehicle is driven with varying and intermittently higher load with attendant temperature increases in the aftertreatment system, the accumulation of crystals may not become undesirably large before the crystals are burned away by the passing exhaust stream. On the other hand, if the vehicle is driven under relatively static conditions with a relatively light load for a period of time, with low temperatures in the exhaust system as a result, then this accumulation of crystals may continue until the performance of the vehicle is adversely affected to an undesirable extent by the increased flow resistance , Thus, the accumulation of crystals may result in adversely affecting the ability of the SCR system to convert NO _x when the supply of urea (eg, spray pattern, amount) is disturbed due to buildup in the form of caking. According to the above, this is solved by the present invention by injecting the additive directly into the combustion chamber.

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

4 schematically illustrates an example of a fuel injection system for in 1A exemplified internal combustion engine 101 The fuel injection system consists of a so-called common rail system, but the invention is equally applicable to other types of injection systems. 4 represents a cylinder / combustion chamber 401 with a piston 403 which is active in the cylinder, wherein the internal combustion engine 101 However, in the present example consists of a six-cylinder internal combustion engine and may generally consist of an engine with any number of cylinders / combustion chambers, for. From any number of cylinders / combustors in the range of 1-20 or even more. The internal combustion engine also includes at least one respective injection element 402 for each combustion chamber (cylinder) 401 , Each respective injector thus becomes injecting / delivering fuel into a respective combustion chamber 401 used. Alternatively, two or more injectors per combustion chamber may be used. The injection elements 402 are individually controlled by respective actuators (not shown) disposed on the respective injection elements which, based on received control signals, e.g. B. from the control device 115 , the opening / closing of the injection elements 402 Taxes.

The control signals for controlling the opening / closing of the injection elements 402 can be generated by some applicable control devices, such. B. in this example by the engine control device 115 , The engine control device 115 thus determines the amount of fuel that is actually to be injected at any given time, e.g. Based on the prevailing operating conditions in the vehicle 100 ,

This in 4 Injection system shown thus consists of a so-called common rail system, which means that all injection elements (and therefore all combustion chambers) fuel from a common rail channel 404 (Common Rail), which is using a fuel pump 405 is filled with fuel from a fuel tank (not shown) at the same time at the same time when the Fuel in the channel 404 pressurized to a certain pressure, also using the fuel pump 405 , If the respective injection element 402 is opened, then the pressurized fuel in the common channel 404 into the combustion chamber 401 of the internal combustion engine 101 injected. Multiple ports / closures of a specific injector may be performed during one and the same combustion cycle, thus multiple injections may be performed during combustion of one combustion cycle. Furthermore, each combustion chamber is provided with a respective pressure sensor 406 equipped to detect signals related to a prevailing pressure in the combustion chamber z. B. to the control device 115 to send. The pressure sensor can, for. B. piezobasiert, and should be fast enough to be able to crank angle resolved pressure signals z. At every 10th, every 5th or every crank angle degree, or at any other suitable interval, e.g. B. more often, to send.

Using a system of in 4 illustrated type combustion during a combustion cycle in a combustion chamber to a large extent z. B. controlled using multiple injections, wherein the times and / or the duration of the injections can be controlled, and wherein data from z. B. pressure sensors 406 can be considered in connection with this control. By using data from e.g. B. the pressure sensor, resulting from the combustion nitrogen oxides can also be estimated, so that the combustion additive z. B. depending on the estimated amount of resulting nitrogen oxides can be supplied. With respect to the supply of additive, each combustion chamber or only a part of the combustion chambers of the internal combustion engine each comprise an injection element 410 , by its use, the addition of the combustion chamber 401 from a tank 411 can be supplied.

5 represents an exemplary method 500 for the supply of additive to the combustion chamber according to the present invention, wherein the method according to the present example is arranged by the engine control device 115 to be carried out in the 1A -B is shown.

In general, controls in modern vehicles consist of a communication bus system that consists of one or more communication buses for connecting a number of electronic control units (ECU), such as a computer. As the control devices or controls 115 , and various components in the vehicle. According to the prior art, such control may include a large number of control devices, and responsibility for a specific function may be distributed over more than one control device.

For reasons of simplification is in the 1A -B only the control device 115 with the present invention implemented in the illustrated embodiment. The invention can be implemented in a control device that is intended especially for the present invention or also completely or partially in one or more other control devices already present in the vehicle. Considering the speed with which calculations according to the present invention are carried out, the invention may be arranged to be implemented in a control device which is particularly adapted for real-time calculations of the type described below. In implementing the present invention, it has been found that e.g. B. ASIC and FPGA solutions are suitable for calculations according to the present inventions, and can handle these well.

The function of the control device 115 (or the controller (s) in which the present invention is implemented) in accordance with the present invention, except that it receives sensor signals from the pressure sensor 202 depends, z. B. be dependent on signals from other control devices or sensors. In general, control devices of the type illustrated are normally designed to receive sensor signals from various parts of the vehicle as well as various control devices present on the vehicle.

The controller is often programmed by programmed instructions. These programmed instructions usually consist of a computer program which, when executed in a computer or controller, causes the computer / controller to perform the desired control action as a method step in the process according to the present invention.

The computer program is usually part of a computer program product, the computer program product being a suitable storage medium 121 (please refer 1B ) and the computer program on the storage medium 121 is stored. The computer program can non-volatile on the storage medium 121 be saved. The digital storage medium 121 can z. B. from any device from the following group: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash, EEPROM (Electrically Erasable PROM), a Hard disk device, etc., and it may be arranged in or in combination with the control device, wherein the computer program is executed by the control device. By changing the instructions of the computer program, the behavior of the vehicle can thus be adjusted in a specific situation.

An exemplary control device (the control device 115 ) is in 1B shown schematically, and the control device may in turn a computing device 120 include, for. B. may consist of a suitable processor or microcomputer type, z. For example, a digital signal processor (DSP) circuit, one or more field programmable gate array (FPGA) circuits or one or more circuits with a specified specific function (Application Specific Integrated Circuit, ASIC). The computing device 120 is connected to a storage device 121 that the computing device 120 z. B. supplied with the stored program code and / or the stored data that the computing device 120 needed to perform calculations. The computing device 120 is also for storing intermediate or final results of calculations in memory device 121 set up.

Furthermore, the control device is with devices 122 . 123 . 124 . 125 equipped to receive and send input and output signals. These input and output signals may include waveforms, pulses, and other characteristics used by devices 122 . 125 for receiving input signals as information and computing device 120 can be processed. devices 123 . 124 for transmitting output signals are for converting the computation result of the computing device 120 in output signals for transmission to other parts of the control of the vehicle and / or the component (s) for which the signals are intended designed. Each of these connections to the devices for receiving and transmitting input and output signals may consist of one or more cables, a data bus, such as a data bus. A Controller Area Network (CAN) bus, a Media Oriented Systems Transport (MOST) bus, or any other bus configuration or wireless connection.

By now we are in the 5 illustrated method 500 Turn to the method begins with step 501 in which it is determined whether, according to the invention, the supply of additives to the combustion chamber should be carried out so that the reduction of nitrogen oxide can be carried out. The controller according to the invention may, for. B. be set to run continuously as soon as the internal combustion engine 101 is started. According to one embodiment, the injection of additive into a combustion chamber is carried out only if, prior to injection, combustion takes place during the same combustion cycle.

The method according to the present invention thus consists of a method for the supply of additive to the combustion chamber of the internal combustion engine 101 while burning in the combustion chamber 201 takes place in combustion cycles. As previously known, the term combustion cycle is defined as the steps involved in combustion in an internal combustion engine, e.g. B. in the two bars of a two-stroke engine and the four strokes of a four-stroke engine. The term also includes cycles in which, in effect, no fuel is injected but in which the engine is still operating at a particular engine speed, such as, for example. B. by the drive wheels of the vehicle via the drive train, z. B. during overrun. That is, even if no injection of fuel is carried out, still one combustion cycle at z. B. two revolutions (for four-stroke engines) or z. B. on each revolution (two-stroke engines) is performed by the drive shaft of the engine. The same applies to other types of internal combustion engines.

In step 502 It is determined whether a combustion cycle has started or will start, and if so, then the method goes to step 503 where an amount of combustion resulting nitrogen oxides is estimated.

In general, the supply of fuel to the combustion chamber is related to the amount and type of delivery, i. H. one or more fuel injections to be performed during the combustion cycle, normally defined in advance, e.g. Depending on the work (torque) that the engine must perform during the combustion cycle.

Fuel injection is thus normally performed according to an injection schedule, wherein multiple injections may be arranged to be executed during one and the same combustion cycle. Combustion in conjunction with these fuel injections gives rise to resulting nitrogen oxides.

According to the present invention, during the combustion cycle, the prevailing pressure in the combustion chamber becomes substantially continuous using the pressure sensor 406 , z. At applicable intervals, e.g. B. every 0.1-10 crank angle degrees determined.

The combustion process in a combustion chamber may generally be described with the pressure change caused by combustion in the combustion chamber. The pressure change during a combustion cycle can be represented by a pressure trace, i. H. a representation of how the pressure in the combustion chamber varies during combustion.

In step 503 Thus, the pressure p _f is substantially continuous in the combustion chamber 401 by the pressure sensor 206 is used during the course of combustion in the combustion chamber. By utilizing the pressure variation, nitrogen oxides NO _x can be generated during the combustion cycle using applicable calculations, with one way of performing the calculation being exemplified below. Alternatively, other models with similar functions can be used.

In general, nitrogen oxides NO _{x are formed} mainly for three different reasons during a combustion process. The fuel may include nitrogen, and nitrogen is released during combustion, and generates at least nitrogen gas N ₂ and nitrogen oxides NO _x . This type of NO _{x formation} , in some types of combustion depending on the type of fuel, may account for a large portion of the total amount of nitrogen oxides NO _x generated during combustion. However, as explained below, this type of NO _{x formation} may occur during normal combustion, e.g. B. ignored according to the diesel cycle. Another source of NO _{x formation} is the so-called prompt NO _{x formation} , but this source generally can go unnoticed because the impact is small relative to other sources. A third source, which during normal combustion is also the main cause of NO _{x formation} during normal combustion at high combustion temperatures, consists of NO _x thermal formation, which is 90-95% or even greater in NO _{x formation} during the combustion cycle.

The NO _{x formation} is thus very dependent on the combustion temperature, and the formation of the thermal NO _x can be described per se in a well-known manner, for. According to the three main reactions (the extended Zeldovich mechanism): N2 + O → NO + NN + O2 → NO + ON + OH → NO + H, (1) Thus, the reaction rate is highly dependent on the temperature, and also the temperature dependence is known as such, so that the amount of formed nitrogen oxides NO _x can be estimated by knowledge of the (substance) amount of the substances contained and the temperature.

According to the present invention, the NO _{x formation} is estimated using the above chemical reaction formula, equation (1), and using an estimate of additional combustion data. The calculation also requires knowledge of the available amount of N ₂ and oxygen O ₂ as well as knowledge of access to hydrogen H. This can be obtained from the chemistry of the combustor known to those skilled in the art and for what the amount of fuel supplied and combustion air, as well as each exhaust gas recirculation, in combination with the fact that the fuel composition is normally known, the amounts of the substances contained in equation (1) can be calculated.

In addition, an estimation of the temperature of combustion for estimating the amount of generated nitrogen oxides NO _{x is} required because the reaction rate depends on the temperature. Similarly, pressure and / or average temperature in the combustion chamber is required to be able to estimate nitrogen and oxygen released during combustion through the combustion chemistry.

In estimating the amount of nitrogen oxides NO _{x formed} , therefore, knowledge about the combustion temperature per se is required. The temperature is higher in the part of the combustion chamber where the combustion takes place, and the combustion chamber can be considered to consist of two zones, the combustion taking place in one zone, resulting in a high temperature in that zone, while in the other zone no combustion takes place, which is a lower temperature for Result has. Overall, an average temperature is thus obtained in the combustion chamber at each moment, which falls below the combustion temperature, where combustion takes place. In order to be able to carry out a desirable determination of the combustion temperature, knowledge about the heat release during combustion is also required.

This can be determined in different ways. For example, as described below, the heat output may be estimated by using a combustion model. This is exemplified in the international patent applications described below. In these applications, future portions of a combustion are estimated while, in accordance with an embodiment of the present invention, pressure signals from the pressure sensor 406 can be used to calculate the heat output during combustion.

, C_p wobei und/oder C_v hergestellt und für unterschiedliche Moleküle tabellarisch dargestellt werden, und da die Verbrennungschemie bekannt ist, können diese tabellarisch dargestellten Werte gemeinsam mit der Verbrennungschemie verwendet werden, um somit die Auswirkung von jedem Molekül (z. B. Wasser, Stickstoff, Sauerstoff usw.) auf z. B. den gesamten C_p Wert zu berechnen, sodass dies für die vorstehenden Berechnungen mit guter Genauigkeit bestimmt werden kann. Alternativ können C_p und/oder C_v auf geeignete Art angenähert werden.The heat release during combustion can be expressed as: dQ = pdV γ / γ - 1 + Vdp 1 / γ - 1 + dQ _HT (2) where dQ is heat given off,
p represents the pressure in the combustion chamber,
V represents the volume in the combustion chamber while
dV represents the volume change of the combustion chamber.
V (φ), that is, the volume of the combustion chamber as a function of the crank angle may advantageously be tabulated in the memory of the control system or may be calculated in an applicable manner, including dV / dφ can be determined.

, C _p where and / or C _v are prepared and tabulated for different molecules, and as combustion chemistry is known, these tabulated values can be used in conjunction with the combustion chemistry to thus determine the effect of each molecule (eg, water , Nitrogen, oxygen, etc.) on z. For example, calculate the total C _p value so that it can be determined with good accuracy for the above calculations. Alternatively, C _p and / or C _v may be approximated in a suitable manner.

d _{p represents} the pressure change in the combustion chamber with the pressure sensor 406 is determined.

d _{QHT represents} the heat output during combustion, which can be determined in a manner which, in the context of the prior art technology, is determined by e.g. B. Woschni is described. Here, the black body radiation in the combustion chamber can be observed in a known manner. In the international patent application PCT / SE2014 / 050493 entitled "METHOD AND SYSTEM FOR CONTROL OF AN INTERNAL COMBUSTION ENGINE""describes a method of estimating the heat emitted during a runaway combustion. The method described in this application can be applied according to the present invention. Furthermore, the method illustrated in the application can be simplified because according to the present embodiment, no estimation of the pressure is required, and pressure signals from the pressure sensor 406 may be used during a running combustion cycle until the time when it is assumed that the maximum amount of nitrogen oxides has been generated according to the following. The application also shows how the heat output before combustion can be estimated.

However, according to the present example, the heat release may be calculated according to the equation (2) by using signals from the pressure sensor 406 to be appreciated. 6 represents a rough approximation of how the heat dissipation 603 during a combustion cycle can change. Instead of expressing the combustion process as a function of time, it is expressed as a function of the crank angle degree φ. 6 also represents the modeled amount of NOx 601 resulting from combustion changes during the combustion cycle, and how the mean temperature 602 changed in the combustion chamber during the combustion cycle.

, wobei T_n=0 die entsprechende Verbrennungslufttemperatur z. B. für den Zeitpunkt/die Kurbelwinkelposition darstellen kann, bei dem/bei der die Ventile nach der Zufuhr von Verbrennungsluft geschlossen werden. The pressure variation p as a function of the crank angle degree .phi. In a cylinder (combustion chamber) for a combustion cycle may be determined by the use of sensor signals from the pressure sensor according to the above 406 to be obtained. Furthermore, the temperature for the part of the combustion chamber in which no combustion takes place can be estimated by using an estimated pressure and by using equation (3), wherein the temperature for the part of the combustion chamber in which no combustion takes place is expressed as:

, where T _{n = 0,} the corresponding combustion air temperature z. B. for the time / the crank angle position may represent, in the / in which the valves are closed after the supply of combustion air.

Further, n, n + 1, etc. represent successive timings or crank angle positions.

K = γ and thus K can also be determined according to what is specified above for γ.

By using equation (3), the temperature for the part of the combustion chamber in which no combustion takes place can be determined, but this temperature is influenced by the combustion occurring by the effect of the heat release on the pressure, which is in the Pressure sensor reflects reflected signals, which in turn affects the temperature according to the equation (3). When combustion takes place, the heat release gives rise to a temperature increase in the part (s) of the combustion chamber in which the combustion takes place. This temperature increase, which is added to the temperature determined according to the equation (3) to obtain the combustion temperature, can be calculated based on the following correlation: dQ = mC _p dT (4) where dQ represents the heat output that can be determined as mentioned above.

m is composed of burned mass (ie, fuel + air + EGR contained in the combustion), which is also determined as mentioned above, C _p , ie specific heat capacity, which can be calculated as described above.

dT represents the temperature increase obtained from the combustion, with a given burned mass and with a given C _p value.

By using equation (4), dT and therefore ΔT can be determined so that the increase produced by the combustion at each time point / each crank angle position can thus be added to the temperature of the part of the combustion chamber where no combustion takes place, as represented by the equation ( 3) to obtain the combustion temperature.

Thus, when the combustion temperature has been estimated, the concentrations and / or absolute amounts of mainly N ₂ and O ₂ can be calculated using the combustion chemistry, so that nitrogen oxides NO _x generated later using equation (1) and combustion temperature dependence are then estimated and estimated below the combustion cycle can be collected. The modeled nitrogen oxides are basically generated until the maximum combustion temperature has been reached, or during a certain time thereafter, which corresponds to the crank angle position φ ₁ in FIG 6 is specified.

Thus, in parallel to the estimation of the resulting nitrogen oxides, it may be determined if _{Tmax has been reached} for the combustion cycle - step 504 If so, then the method with step 505 for determining an applicable amount of additives for injection into the combustion chamber 201 using the injection element 410 continues, wherein the applicable amount of additive for injecting z. B. can be determined by the use of known chemical correlations in reactions between additives and nitrogen oxides. For example, the amount of additive can be determined as a stoichiometric amount of additive, that is, the amount of additive needed to completely convert the amount of nitrogen oxides. The amount supplied to the combustion chamber additive can also z. B. consist of an applicable fraction of a stoichiometric amount, such as. B. more or less than these Amount. For example, it may be desirable to reduce nitrogen oxides _NOx only to a certain extent, which means that a smaller amount can be supplied. For example, an amount may be supplied which is expected to result in the emissions of the vehicle meeting the prevailing regulatory requirements as to where the vehicle is driven.

Alternatively, the amount may be arranged to exceed the stoichiometric amount, e.g. B. with the aim to achieve a high reaction rate. The amount may also be adjusted to fall below the stoichiometric amount, e.g. B. when only a certain reduction in the combustion chamber is required or desired. A further reduction may be needed when and when needed, e.g. B. using an SCR catalyst can be achieved, as described above.

According to one embodiment, the temperature of the combustion chamber is also used, ie the temperature tracking 602 in 6 to determine the applicable amount of additive, wherein the reaction rate is very dependent on temperature, so that the amount of additive thus z. B. as a function of one or more of the amount of resulting nitrogen oxides, pressure in the combustion chamber, temperature in the combustion chamber can be determined.

According to one embodiment, the amount of resulting NO _{x is} subsequently estimated, so that when it is determined that it has reached its maximum and / or starts to decrease, such as. B. at or after the position φ ₁ in 6 which normally also occurs via chemical reactions other than reaction with an additive, although at a significantly lower reaction rate, the applicable amount of additives may be determined for delivery.

The addition will then be in step 506 injected so that the procedure to step 501 for a new determination for a subsequent combustion cycle can return. According to the present invention, the amount of resulting nitrogen oxides can be estimated during a combustion cycle so that an amount of additive adapted to the amount of generated nitrogen oxides can be injected into the combustion chamber to already achieve the reduction of nitrogen oxides in the internal combustion engine, wherein a high temperature prevails, and why no SCR catalyst is needed. The present invention thus has the advantage that the need for an SCR catalyst can be completely eliminated or at least reduced. According to one embodiment, if necessary, additives can also be injected upstream of an SCR catalyst, wherein z. For example, a smaller SCR catalyst could then be used otherwise, but in many cases the need for an SCR catalyst is completely eliminated when the present invention is used. Furthermore, problems with crystal formation, etc. due to low temperatures according to the above can also be avoided completely or to a large extent according to the present invention.

According to one embodiment, an injection of additives is carried out only when the average temperature of the combustion chamber has an applicable temperature T _lim , z. B. 700-750 ° C exceeds. This embodiment, according to the above, requires not only knowledge about the temperature of the combustion but also about the average temperature for the combustion chamber, ie the curve 602 in 6 , This mean temperature 602 can z. B. as described in the international patent application PCT / SE2014 / 050491 which describes in detail how the average temperature in a combustion chamber can be estimated by using e.g. B. the pressure in the combustion chamber can be estimated with the pressure sensor 406 can be obtained.

According to the method set forth in the application, an estimation is made for the future time, and such an estimate can also be applied to the present invention so as to estimate by estimation the applicable amount for injection before the generated nitrogen oxides have reached the maximum level. In this case, the model represented in the application or another applicable model of combustion may also be used.

In one embodiment, however, the fact is used that pressure signals from the pressure sensor 206 representing the currently prevailing pressure in the combustion chamber can be used to the point when the amount of nitrogen oxides has reached the maximum amount of nitrogen oxides, eg. B. the position φ ₁ in 6 so that no estimation is required, and where the heat output can be estimated according to the above, and wherein the mean temperature z. B. can be determined according to the general gas law. Thus, according to one embodiment, it may be determined that the temperature is sufficiently high to cause the desired reactions, such as e.g. B. when the prevailing mean temperature in the combustion chamber 700-750 ° C, wherein such an average temperature is thus below Use of the general gas law can be determined in a known manner, and as it is also shown in the application, so that the unwanted crystal formation can be avoided.

Thus, according to one embodiment, the injection is carried out only when the temperature exceeds the temperature T _lim in 6 is shown, so that the interval φ ₁ - φ _{2 represents} a "window" in which the injection of additive should occur. This "window can also z. B. with respect to the maximum temperature, ie, the injection may be arranged to only enter when the temperature in the combustion chamber is below an applicable temperature, thus φ ₁ to the right in 6 can be moved. Furthermore, it should be noted that the injection of additive need not be performed precisely when combustion is currently taking place in the combustion chamber, but injection may occur at any location within the combustion chamber, e.g. With the additional condition that the mean temperature does not fall below T _lim .

According to one embodiment, this can be found in the international patent application PCT / SE2014 / 050491 illustrated methods are also applied to z. B. before the position φ ₁ to estimate whether the average temperature will be high enough for an injection is possible, and if it is concluded that this is not the case, for. For example, additional fuel injection may be performed based on such an estimate, with the aim of increasing the temperature in the combustion chamber to activate the injection of additive.

If this injection is carried out late enough during the combustion cycle, then the injection does not contribute to NO _{x formation} but increases the temperature. In the application of such additional injection, it may be arranged in advance to be of a predetermined size, but it may also be arranged to be determined using an estimate according to the method described in International Patent Application PCT / SE2014 / 050491 is shown, for. To determine the applicable amount of fuel for injection separately or in concert with the injection of additive to obtain the desired temperature.

According to the embodiment described so far, the estimation of the resulting amount of nitrogen oxides has been carried out during the running combustion cycle, so that the amount of additive is likewise supplied based on the estimated resulting amount of nitrogen oxides.

According to one embodiment, nitrogen oxides are estimated during a combustion cycle, based on this estimate, injection of the additive is also performed during one or more consecutive combustion cycles. This has the advantage that the estimate can be carried out less frequently.

According to a simpler form of the invention, no estimation of nitrogen oxides is carried out, but it is injected additive at the applicable time in the combustion chamber, wherein z. Instead, for example, the injected amount may be arranged to be dependent on the amount of fuel supplied to the combustion, or a standard amount may always be used, e.g. B. as long as at least a minimum amount of fuel is injected. However, according to a preferred embodiment, an estimation of the resulting nitrogen oxides is carried out.

Furthermore, the invention has hitherto been described in connection with a method in which the nitrogen oxide formation is estimated up to the point in time during the combustion cycle, to which it is assumed that nitrogen oxides have been formed. According to the above, this is indicated by the crank angle position φ ₁ . According to the embodiment shown, the control system thus has knowledge of the occurrence of the pressure change in the combustion chamber 401 to the position φ ₁ , since it is possible to do so using the pressure sensor 406 to determine. Assuming that the nitrogen oxide formation is completed, the amount may be estimated using the actual pressure development, and an applicable amount of additive for injection during the subsequent portion of the combustion cycle may be determined based on the estimated amount of nitrogen oxides NO _x .

Furthermore, the prevailing temperature in the combustion chamber 401 be estimated using the pressure change actually detected so that the applicable time to inject the additive can be determined, and so that the injection takes place when the temperature in the combustion chamber 401 within a desired temperature range.

According to one embodiment of the invention, the injection of additive is instead carried out at an earlier stage during the combustion cycle, e.g. B. completely or partially before the combustion is initiated or terminated, such. B. completely or partially before the fuel injection is initiated. An example of such a method is in 7 illustrated. 7 sets the pressure p in the combustion chamber 401 as a function of the crank angle degree φ. In 7 puts in a continuous line 701 the pressure change in a combustion chamber when no combustion is being performed, ie, the pressure variation experienced by the chamber due to the forward and backward movement of the piston when the intake and exhaust valves are closed. φ _IVC represents the crank angle degree with the intake valves closed, and φ _EVO represents the crank angle degree with the exhaust valves open, and thus the atmospheric pressure atm or the prevailing combustion air pressure prevails. φ _TDC represents the top dead center of the piston. The dashed line 702 represents the pressure change that arises in the combustion chamber as a result of the combustion, in which example the combustion is initiated substantially at the top dead center of the piston φ _TDC . The hatched area 703 thus represents the pressure change caused by the combustion. In the above example, the injection of additive was performed during the part of the combustion cycle following the crank angle position φ _A , that is, after reaching the maximum pressure substantially equal to the position where the temperature is maximum even during the combustion cycle ,

In one embodiment, the additive is added instead before combustion is initiated, ie, during the time that begins when intake valves are closed at φ _IVC until combustion is initiated, ie, in the example, in the interval φ _IVC - φ _TDC . For example, the supply of overhead may be arranged to operate within an applicable partial interval of the interval φ _IVC - φ _TDC , e.g. B. between the time φ _B - φ _C in 7 to be executed. φ _B can z. B. be set so that the temperature in the combustion chamber exceeds an applicable temperature.

According to the in 6 In the example shown, the NO _x level may be substantially estimated when the combustion has ended, so that the measured pressure may be used in the calculation model according to the above for calculating generated nitrogen oxides NO _x . In the case where additive is added before combustion has started, actual pressure tracking may occur 701 up to the position (eg, φ _A in 7 ) are not used, where it is assumed that the nitrogen oxides were formed in order to estimate the occurrence of the nitrogen oxide after combustion, since the combustion has not yet occurred. At the same time, it is desirable to add an amount of additive that matches the amount of nitrogen oxides that will be formed later during the combustion cycle. The applicable amount of additive can be determined in several different ways. According to one embodiment, the generated nitrogen oxides NO _{x are} estimated according to the above during a combustion cycle, so that the additive is supplied only during a subsequent combustion cycle. This method can, for. For example, when the conditions for a plurality of consecutive combustion cycles are substantially the same.

According to one embodiment, an estimation of the nitrogen oxides NO _x formed during the subsequent part of the combustion cycle so that supplement is supplied before combustion actually occurs and based on an estimated result of the combustion is performed. The amount of generated nitrogen oxides can be estimated according to the above equations, however, knowledge about future pressure changes in the combustion chamber is a prerequisite since there is no knowledge about it. The pressure change in the combustion chamber can, for. B. according to the international patent application PCT / SE2014 / 050495 which describes a method of estimating the amount of nitrogen oxides produced so that the combustion can then be controlled based on the expected amount of nitrogen oxides.

According to the present invention, the method exemplified in the application can be used to estimate the amount of nitrogen oxides generated, the application exemplifying how the pressure change can be estimated during a future part of the combustion cycle, such that the estimated pressure in the above described calculations can be used. As described in the application, knowledge of the amount of fuel that will be injected during the combustion cycle and when the injection occurs is required for the calculation. However, this usually represents known data, which have also been described above in connection with the calculation of the heat emission due to combustion, and thus more in detail in the international patent application PC / SE2014 / 050493 describing the prediction by estimating the heat output for a future part of the combustion cycle, which is thus executed when the calculations are performed using an estimated pressure.

By using the method described in the international patent application PC / SE2014 / 050495 is shown, the expected amount of nitrogen oxides NO _x thus formed before the time φ _B in 7 so that an applicable amount of additive for injection in front of / at the position φ _B in 7 can be determined, so that such an amount then z. B. during the interval φ _B - φ _C can be injected into the combustion chamber. The amount of additives for feeding can, for. B. consist of a stoichiometric or other applicable amount. For example, it may be desirable to add a greater amount of additive than is ideally consumed to reduce the expected amount of nitrogen oxide, since the additives were "burned" during combustion, thus reducing the NO _x reduction efficiency.

Furthermore, injection of additive prior to combustion will affect the combustion process itself. As it is obviously the case, this depends z. B. on whether the combustion chamber is additionally supplied substance. In addition, the additive is normally a liquid, wherein the liquid is a relatively large fraction of z. B. may contain water. The supplied liquid evaporates completely or to a large extent, consuming energy in the evaporation, with the result that the temperature in the combustion chamber is reduced. In addition, the dissociation effect occurs when gaseous water molecules are split into hydrogen and oxygen respectively, consuming energy for molecular splitting. This, in turn, has an effect on combustion, where a reduced temperature may result in a smaller amount of nitrogen oxides being produced, as a result of which a smaller amount of additive is required only because of this ratio.

Thus, in the calculation of the expected formation of nitrogen oxides NO _x, the amount of added additives should be taken into account, which is why the additives should also be included in the calculation. This, in turn, may require that iterations be required to find an amount of feed to be added that corresponds to the amount of nitrogen oxides produced upon combustion after it has been added.

With respect to the calculations, the additive affects the specific heat capacity in the combustion chamber and thus affects gamma γ in the above equations. More specifically, the effect of the change in the specific heat capacity can be obtained by calculating the specific heat capacity each at a constant pressure C _P and at a constant volume C _V , and the exhaust gas recirculation EGR is also treated in the following calculation.

Heat capacities are tabulated for different chemical substances and elements in tables provided by NASA, and are interpolated as a function of temperature, using the average temperature of the combustion chamber. This temperature can z. B. as described in the international patent application PCT / SE2014 / 050491 which describes in detail how the average temperature in a combustion chamber z. B. can be estimated by using the pressure in the combustion chamber, which can be estimated according to the above. In general, the specific heat capacity at a constant pressure C _{P is} tabulated in the following form:

The specific heat capacity for a constant volume, C _V , can then be calculated as C _V = C _P - R, so that gamma γ can thus be calculated. When gamma γ is calculated, the generated amount of nitrogen oxides can be estimated according to the above. The effect of the additive on gamma γ is described below.

As noted, it may also be advantageous to note during calculation of gamma γ when EGR recirculation is performed, ie, when some of the exhaust gases are returned from combustion to the intake side of the internal combustion engine, which has an effect on the chemical composition in the combustion chamber has. Control of EGR recirculation normally consists of its own regulation, however, as described above, it may be advantageous to adjust EGR recirculation based on the amount of additive added. If EGR feedback is used, z. For example, the following correlation may be used to estimate specific heat capacity at a constant pressure for EGR-recirculated gas, where a and b are the numbers of carbon atoms and hydrogen atoms, respectively, in the fuel used to propel the vehicle, ie, C _a H _b and where λ _gl represents the lambda value.

A corresponding calculation of the specific heat capacity at a constant volume for clean air consists of:

With the aim of obtaining a correct gamma value, the respective heat capacity is weighted according to equation (8), where EGR% represents the EGR level: C _p = C _pAIR * (1-EGR%) + C _pEGR * EGR% (8) the EGR level may, for. B. determined as a determined during a previous combustion cycle EGR level. Alternatively, the EGR level z. B. be determined by emission calculations, wherein z. For example, carbon dioxide calculations may be used to determine how much of the combustion air is that of recirculated exhaust gases. For example, this may be done by measuring the carbon dioxide level at the inlet to the combustor and at the outlet of the combustor, or further downstream in the aftertreatment system so that the EGR level can be calculated in a manner known to those skilled in the art. The EGR feedback thus represents a variable that is not calculated specifically for each combustion cycle but is normally available in the control system of the vehicle, which is calculated at applicable intervals. In general, EGR feedback control is much slower than control according to the present invention.

, wobei

bekannt und tabellarisch dargestellt sein kann. Alternativ kann c_{p tillsmedel}(T) auf dieselbe Art wie vorstehend für c_{p EGR} beschrieben durch Wissen über die Zusammensetzung des Zusatzes bestimmt werden. Gamma γ kann dann bestimmt werden als:

, wobei:

With respect to the effect of the additive on specific heat capacity, and thus gamma γ, this can be determined using the following equation:

, in which

can be known and tabulated. Alternatively, c _{p tillsmedel} (T) can be determined in the same manner as described above for c _{p EGR} by knowledge of the composition of the additive. Gamma γ can then be determined as:

, in which:

By using a calculated γ equalized to inject additive before combustion, the expected nitrogen oxides generated during combustion can thus be estimated according to the above, so that it can be concluded that a smaller amount of additive is required, so a new calculation for a smaller amount of additive, etc. The applicable amount of pre-combustion injection additive may thus be iterated until the desired amount of additive is obtained in relation to the expected amount of nitrogen oxides formed in the calculations.

Additional aspects should be considered in conjunction with the addition of combustion additive according to the present invention. For example, EGR recirculation of a portion of the exhaust gases formed during combustion is normally employed. EGR feedback generally has a positive (reducing) effect on e.g. B. the formation of NO _x . The Supply of additive leads to a modified exhaust gas flow composition compared to the case where no additive is supplied. For example, the additive according to the above may be partially made of water, so that it is likely that a greater proportion of water than normally present, in the resulting exhaust gas flow occurs. That is, regulation of EGR feedback may be required based on the addition of supplement. For example, EGR recirculation may be required to be reduced due to a relatively higher water content in the exhaust stream, resulting in a better NO _x reduction effect, but at a risk that an undesirably high water content in the exhaust gas will be lost Combustion chamber can be obtained if the EGR feedback in relation to the water content is too high.

The control of the EGR feedback can be carried out in any suitable manner, wherein z. For example, the effect of EGR feedback on the specific heat capacity may be taken into account in accordance with the above, and where the EGR feedback is based on these calculations, e.g. B. can be controlled. In general, the EGR recirculation is slow (in the range of seconds) as compared to the executed control according to the present invention, wherein calculations are performed during the running combustion cycle, and calculations such. B. in a hundredth of a second, a thousandth of a second or even a shorter time can be performed.

Furthermore, additional aspects should be considered during the addition of additives to the combustion chamber. The pressure in a combustion chamber may increase to relatively high pressures, such. B. a maximum pressure in the range of 200-300 bar. Normally, the fuel injection is carried out at substantially higher pressure than the combustion chamber pressure, z. At 1,500-2,500 bar, such that changes in the pressure of the combustion chamber become substantially negligible relative to the high fuel injection pressure. That is, the injected amount of fuel can be determined with good accuracy. However, the use of high pressures is usually associated with high costs and therefore it is highly desirable to carry out the injection of additive at much lower pressures, e.g. B. at a pressure in the same size range as the prevailing combustion chamber pressure. This in turn means that due to the backpressure of the combustion chamber for a given opening time of the injector for injecting additives different amounts for one and the same opening time depending on the prevailing chamber pressure can be supplied. Thus, the injection of the additive may be arranged to be controlled based on the prevailing combustion chamber pressure, e.g. B. using the pressure sensor 406 can be determined.

Thus, at prevailing higher combustion chamber pressures, a longer opening time may be used compared to when the prevailing combustion chamber pressure is lower, the combustion chamber pressure apparently being dependent on the crank angle position at which the injection of additive occurs.

Furthermore, the present invention comprises a solution in which liquid, such as. B. partially water-containing liquid, the combustion chamber of the internal combustion engine is supplied. This hydration may require that certain protective aspects / measures be considered. According to the above, in the case of injection of additive after combustion, a low temperature limit may be exemplified for the desired conversion to occur. There may also be restrictions for other reasons as to where injection of additives should occur during the combustion cycle. For example, it may be desirable for the piston to be positioned at its maximum a certain number of crank angle degrees from its top dead center when injection occurs so that a not too large portion of the cylinder wall is exposed during injection, with a risk of impacting the cylinder Wall, and whereupon the oil film is washed away as a result, thus causing a concomitant risk of undesirable wear.

Furthermore, the supply of additional z. Example, be set to be closed when the speed of the vehicle falls below a certain speed or when the vehicle comes to a standstill, or if for any other reason there is a risk that the engine will soon shut down. In such situations it may be desirable that e.g. For example, the presence of water in the engine system is reduced before the engine is shut down to prevent water-related damage. According to an embodiment of the invention, the supply of additive may be arranged to be switched off when the speed of the vehicle falls below an applicable speed, and when the ambient temperature of the vehicle is below e.g. B. zero degrees Celsius, with the aim of avoiding that water remains in the system after the engine has been switched off, which would result in a risk of freezing.

Further, the above embodiments may be combined with a method that stops the combustion as the combustion process proceeds, the combustion being controlled based on an applicable criterion. In the international patent application PCT / SE2014 / 050495 For example, a method is described in which combustion is controlled during the combustion cycle based on an expected and estimated amount of resulting nitrogen oxides during an ongoing combustion cycle. According to one embodiment, the method according to the invention may be combined with the method presented in the application so that the amount of resulting nitrogen oxides NO _{x can be established} prior to the addition of additive to be controlled by the control of the combustion. Furthermore, the amount of additive for delivery to the combustor may be configured to be based on an estimate of the resulting nitrogen oxides as described in the international patent application PCT / SE2014 / 050495 to be determined.

Furthermore, the method may be arranged to be interrupted when the temperature in the combustion chamber has reached the maximum temperature during combustion, when substantially all of the nitrogen oxide production is likely to occur prior to that time, so that subsequent control may instead be accomplished, for example. B. can be performed completely according to the selected injection timing, or can be performed based on another applicable criterion.

The invention has often been exemplified in a manner in which a pressure sensor 406 is used for determining a pressure in the combustion chamber, and with the aid of which the temperature and the nitrogen oxide production can be estimated as described above. An alternative use of pressure sensors may instead be the use of one (or more) other sensors, e.g. High-resolution ion current sensors, knock sensors or strain gauges, wherein the pressure in the combustion chamber can be modeled using sensor signals from such sensors. It is also possible to combine different types of sensors, e.g. To obtain a more reliable estimate of the pressure in the combustion chamber and / or to use other applicable sensors, the sensor signals being converted into corresponding pressures for use in the control, as described above.

The method according to the invention for controlling the internal combustion engine can also be combined with sensor signals from other sensor systems, wherein the resolution of the crank angle level is not available, such. B. another pressure transmitter, NOx sensors, NH3 sensors, PM sensors, oxygen sensors and / or temperature transmitter, etc., whose input signals z. B. as an input parameter in the estimate z. B. the expected pressure / the expected temperature may be used, by complete or partial use of computerized models instead of models of the type described above. For example, signals from a NO _x sensor arranged downstream of the internal combustion engine, for determining the applicable amount to be used for addition to the combustion chamber. In this case, z. For example, an undesirably high NO _x level indicated by the NO _x sensor will result in an increase in the amount of reductant added.

In addition, the present invention has been exemplified above in relation to vehicles. However, the invention is also applicable to any vehicles / processes in which the nitrogen oxide control as described above is applicable, such as. As watercraft or aircraft with combustion processes, as described above.

It should also be noted that the system may be changed according to various embodiments of the method according to the invention (and vice versa), and the present invention is in no way limited to the above-described embodiments of the method according to the invention, but to all Embodiments and includes within the scope of the appended independent claims. For example, the invention is applicable to the injection of any additive in the combustion chamber of the internal combustion engine, wherein such additive for reducing nitrogen oxides or of one or more other pollutants may be provided.

Claims (53)

Method for controlling an internal combustion engine ( 101 ), wherein the internal combustion engine ( 101 ) at least one combustion chamber ( 201 ) and elements ( 202 ) for supplying fuel to the combustion chamber ( 201 ), wherein the combustion in the combustion chamber ( 201 ) takes place in combustion cycles, the method being characterized by: Determining during a first combustion cycle and using a first sensor element ( 406 ), a first parameter value that is a quantity relative to the combustion chamber ( 201 ), determining a first amount of additive for supplying to the combustion chamber by using the first parameter value, and supplying the first amount of additives to the combustion chamber ( 201 ). The method of claim 1, wherein the first parameter value representing an amount related to the combustion chamber ( 201 ), a lot in relation to the combustion in the combustion chamber ( 201 ). A method according to claim 1 or 2, wherein the additive is an additive for the reduction of at least one first substance (NO _x ) resulting from the combustion in the combustion chamber ( 201 ) results. A method according to any of claims 1-3, further comprising: - estimating a first measure of at least a first substance (NO _x) using the first parameter value resulting from the combustion during a first combustion cycle, and - based on the first level determining the first amount of additive for supplying to the combustion chamber. The method of claim 4, further comprising estimating the first measure during the first combustion cycle. The method of any one of claims 1-5, further comprising when adding combustor additives during a combustion cycle: At least partially supplying the additives before the combustion is initiated or terminated during the combustion cycle. The method of any one of claims 1-6, further comprising when adding combustor additives during a combustion cycle: - At least partially supplying the additives before a working in the combustion chamber piston reaches the top dead center. The method of any one of claims 1-7, further comprising when adding combustor additives during a combustion cycle: Supplying the additives at least partially before fuel injection is initiated or terminated during the combustion cycle. The method of any one of claims 1-8, further comprising when adding combustor additives during a combustion cycle: - At least partially supplying the additives before the maximum pressure and / or the temperature is reached during the combustion cycle. The method of any of claims 1-9, further comprising when adding combustor additives during a combustion cycle: - At least partially supplying the additives in dependence on the prevailing during the combustion cycle air / fuel ratio. The method of any one of claims 1-10, wherein combustion gas is supplied to the combustion chamber via at least one intake valve, further comprising at least partially adding the additive to the combustion chamber after the at least one intake valve has been closed. The method of any of claims 1-11, further comprising: Supplying the first amount of additive to a second combustion cycle following the first combustion cycle. The method of claim 12, further comprising: estimating a first amount of at least one first substance (NO _x ) resulting from combustion during the first combustion cycle, determining a first amount of additive to supply to the combustion chamber based on the first measure of combustion first substance, and - supplying the first amount of additives to a second combustion cycle following the first combustion cycle. The method of claim 13, further comprising: estimating a second measure of the at least one first substance (NOx) _x ) resulting from the combustion during the second combustion cycle, determining a second amount of additive for supplying to the combustion chamber based on the second measure the first substance, and - supplying the second amount of additives to a third combustion cycle following the second combustion cycle. The method of claim 13 or 14, further comprising repeating the estimation of measures of the first substance, determining addition for feeding, and supplying additive for a plurality of consecutive combustion cycles. The method of any one of claims 4, 5, 13-15, further comprising: estimating the first measure of at least one first substance (NO _x ) resulting from combustion during a first combustion cycle, and based on the first measure, adding Additions to the combustion chamber during a subsequent part of the first combustion cycle. The method of any one of claims 4, 5, 13-15, further comprising: estimating the first measure of at least one first substance (NO _x ) resulting from combustion during a first combustion cycle, and at least partially based on the first measure Adding the additives to the combustion chamber before combustion begins during the first combustion cycle. The method of any one of claims 4, 5, 13-15, further comprising: estimating the first measure of at least one first substance (NO _x ) resulting from combustion during a first combustion cycle, and at least partially based on the first measure Adding the additives to the combustion chamber before combustion ends during the first combustion cycle. The method of any one of claims 16-18, further comprising: estimating the effect of adding additive in estimating the first measure of at least one first substance (NO _x ) resulting from combustion during the first part of the first combustion cycle combustion to the first degree. A method according to any one of claims 16-19, further comprising: - determining a first amount of additive to supply to the combustion chamber, estimating a second measure of at least one first substance (NO _x) resulting from the combustion during the first combustion cycle, wherein a supply of the first amount of additive before combustion, and - correcting the amount of additives for supplying to the combustion chamber based on the second measure. The method of claim 20, further comprising: iteratively estimating measures of at least a first substance (NO _x ) resulting from the combustion during the first combustion cycle, and iteratively correcting the first amount of additives based on the determined measure until a Measure of at least one first substance (NO _x ) resulting from the combustion during the first combustion cycle satisfies a first condition. The method of any one of claims 4, 5, 13-21, wherein the estimated first measure is an estimated level of the first substance (NO _x ) for the exhaust gases resulting from the combustion. The method of any one of claims 4, 5, 13-22, wherein the estimated first measure is an estimated resulting amount of at least one first substance (NO _x ) for at least a portion of the first combustion cycle. The method of any one of claims 4, 5, 13-23, further comprising supplying the additive to a combustion cycle following the first combustion cycle based on the first measure. The method of any of claims 4, 5, 13-24, further comprising: Estimating the resulting amount of at least one first substance (NO _x ) based at least in part on an estimated combustion temperature. The method of claim 25, wherein the combustion temperature is estimated at least in part by estimating heat output during combustion. The method of claim 26, further comprising estimating the heat output using knowledge about an amount of fuel provided for delivery to the combustion. The method of any one of claims 25-27, further comprising estimating the amount of available nitrogen (N ₂ ) and the amount of available oxygen (O ₂ ) at least in part using knowledge about an amount of fuel provided for feeding to the combustion; wherein the amount of the at least one first substance (NO _x ) is estimated at least in part based on the stated available amounts of nitrogen and oxygen. Method according to one of claims 25-28, wherein the combustion temperature based at least in part on the pressure in the combustion chamber ( 201 ) is estimated. The method of claim 25, further comprising estimating the combustion temperature as a sum of an estimate of a temperature increase caused by combustion relative to a first temperature, and an estimate of the first temperature, wherein the first temperature is an estimated unburned gas temperature represents the combustion chamber. The method of any one of claims 4, 5, 13-30, further comprising estimating the generated amount of at least one first substance (NO _x ) at least in part using a Zeldovich mechanism. The method of any of claims 4, 5, 13-31, further comprising, when the first measure of the first substance (NO _x ) for combustion is estimated: - interrupting the estimation when the estimation has been performed to a point where a maximum temperature is expected during combustion. Method according to one of claims 1-32, wherein the first parameter value is one in the combustion chamber ( 201 ) represents prevailing pressure. Method according to one of the preceding claims, further comprising: Determining whether the temperature during combustion during the combustion cycle has reached the maximum temperature during the combustion cycle, and - Determining the amount of additive for supplying to the combustion chamber when the maximum temperature has been reached. The method of claim 1, further comprising determining an amount of additive to supply to the combustion chamber, based at least in part on one or more of the group: chemical correlations for reactions between additives and nitrogen oxides, the temperature of the combustion chamber, signals from a NO _x sensor, which is located downstream of the engine. The method of any one of the preceding claims, wherein exhaust gases resulting from combustion in the combustion chamber pass through an SCR catalyst further comprising injecting additional additive downstream of the internal combustion engine but upstream of the SCR catalyst. The method of any one of the preceding claims, wherein exhaust gases resulting from combustion in the combustion chamber pass through an SCR catalyst, further comprising injecting additives into the combustion chamber for at least partial use for reduction in the SCR catalyst. Method according to one of the preceding claims, wherein the injection of additive to the combustion chamber is carried out only when the temperature of the combustion chamber exceeds a first temperature. The method of claim 1, further comprising, when the temperature of the combustion chamber falls below a first temperature, performing an additional fuel injection to increase the temperature in the combustion chamber, before or simultaneously with the supply of additive. The method of claim 1, further comprising determining the amount of additive to supply to the combustion chamber based at least in part on the amount of fuel supplied to the combustion chamber. The method of any one of the preceding claims, further comprising determining the amount of individual injection additives for each cylinder. The method of any one of the preceding claims, wherein the control is performed for a number of consecutive combustion cycles. Method according to one of the preceding claims, wherein the additive is an additive for the reduction of nitrogen oxides (NO _x ), which from the combustion in the combustion chamber ( 201 ) result. Method according to one of the preceding claims, wherein the first level of nitrogen oxides (NOx) _x ), resulting from the combustion during the first combustion cycle, consists of a level of resulting nitrogen monoxide (NO) and / or nitrogen dioxide (NO ₂ ). Method according to one of the preceding claims, wherein the additive consists of a fuel-separated additive. Method according to one of the preceding claims, wherein the additive consists of an additive containing urea and / or ammonia. The method of any one of the preceding claims, further comprising adding the additive directly into the combustion chamber. A computer program comprising program code which, upon execution of the program code in a computer, causes the computer to perform the method of any of claims 1-47. A computer program product comprising a computer readable medium and a computer program according to claim 48, wherein the computer program is contained within said computer readable medium. System for controlling an internal combustion engine ( 101 ), wherein the internal combustion engine ( 101 ) at least one combustion chamber ( 201 ) and elements ( 202 ) for supplying fuel to the combustion chamber ( 201 ), wherein the combustion in the combustion chamber ( 201 ) is carried out in combustion cycles, the method being characterized in that the system comprises: elements ( 115 For determining during a first combustion cycle and using a first sensor element (FIG. 406 ), a first parameter value is set, which is a quantity relative to the combustion chamber ( 201 ), - elements ( 115 ) configured to determine a first amount of additives to be supplied to the combustion chamber using the first parameter value, and elements ( 115 . 410 ) for feeding the first amount of additives to the combustion chamber ( 201 ) are set up. A system according to claim 50, characterized in that the internal combustion engine comprises elements for supplying additive to the combustion chamber. A system according to claim 50 or 51, characterized in that the internal combustion engine consists of one of the following group: a vehicle engine, a marine engine, an industrial engine. Vehicle ( 100 ), characterized in that it comprises a system according to any of claims 50-52.

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