DE102015210745B4 - System and method for predicting the timing of combustion in an engine with homogeneous compression ignition - Google Patents

Abstract

A system for predicting a time of combustion of a mixture inside a cylinder (21) for a combustion cycle of an HCCI internal combustion engine (2), comprising:
Determining at least two combustion _{reaction parameters} from combustion _{reaction parameters} , which is a pressure state _variable (P _{cyl_10BTDC} ), which is determined based on a cylinder pressure inside the cylinder (21), a fuel _{mass fraction} (φ, φ ^-1 ), which is based on the state of the fuel mass and the Air mass inside the cylinder (21) is determined and a variable in the state of the burned gas (X _rg ), which is determined based on the retention of the burned gas inside the cylinder (21);
Including the determined at least two combustion reaction parameters in an Arrhenius equation; and
Predicting a time of combustion (CA50) for the combustion cycle using the Arrhenius equation, where the time of combustion (CA50) corresponds to a crank angle (CA) at which a mass fraction of the fuel burned is 50%.

Description

TECHNICAL AREA

The present invention relates to a system and a method for predicting a time of combustion for a combustion cycle in a cylinder of an engine with homogeneous compression ignition.

GENERAL PRIOR ART

In recent years, homogeneous charge combustion ignition (HCCI) engines have been proposed that use combustion as a form of combustion, which is caused by auto-ignition of an air-fuel mixture by admission of burned gas at a high temperature into one Cylinder is triggered. This form of combustion, which is triggered by homogeneous compression ignition and is referred to as combustion with homogeneous compression ignition (HCCI), has received attention as a form of combustion for gasoline and diesel engines.

HCCI combustion is caused by auto-ignition without any help from a spark, which is caused by an increase in the temperature and pressure of an air-fuel mixture in a cylinder, which is obtained by compression of the mixture. This HCCI combustion, in which a “mass” combustion takes place simultaneously from several ignition points in the mixture in the cylinder, has the advantage that a higher thermal efficiency with a short burning time is obtained.

For example, if HCCI combustion is used in gasoline engines, engine manufacturers will be able to expect an improvement in fuel consumption. In addition, engine manufacturers will primarily expect a reduction in soot and nitrogen oxide emissions when using HCCI combustion in diesel engines.

The timing of auto-ignition in an HCCI engine that uses HCCI combustion differs depending on various types of state variables of a charge of the mixture in a cylinder, including the temperature of the charge in the cylinder, the pressure of the charge in the cylinder, and the like The amount of air in the charge in the cylinder, the amount of residual gas in the charge in the cylinder, the amount of fuel in the charge in the cylinder, and the like are considerable. This poses a problem in that the engine may knock or misfire if the auto-ignition timing is not properly controlled because the charge may not burn at the appropriate time. Therefore, there is a need to predict with good accuracy the timing of the combustion of the charge caused by auto-ignition.

The prior art includes HCCI internal combustion engines that predict the timing of the combustion of the air-fuel mixture that is triggered by auto-ignition during the HCCI combustion mode, as in FIG JP 2009 - 168027 A (also as US 2009 / 0,182,485 A released), JP 2006-2637 A , and JP 2008-101591 A described below as Patent Literature Examples 1 to 3.

The in JP 2009-168027 A The HCCI internal combustion engine described predicts the 50% combustion center of gravity in one cycle by an equation that predicts the 50% combustion center of gravity based on the manipulated variables in terms of residual gas retention and / or the air supply that is admitted to the internal combustion engine in the cycle , the amount of fuel injected in the previous cycle, the induced mean pressure determined for the previous cycle, the 50% center of combustion determined for the previous cycle, and parameters.

The HCCI internal combustion engine, which in JP 2006-2637 A describes the ignition delay using the Arrhenius equation, which predicts the ignition delay based on parameters such as the pressure of a charge of an air-fuel mixture, the temperature of the charge and the air-fuel ratio of the mixture and the like were determined.

The HCCI internal combustion engine, which in JP 2008-101591 A is described using the Arrhenius equation which predicts the predicted ignition delay Based on the pressure of a charge of the mixture in a cylinder, the activation energy, the absolute temperature of the charge in the cylinder, the gas constants and various constants.

US 2010/0 058 832 A1 discloses an apparatus for predicting the amount of soot formed in an internal combustion engine, particularly in a diesel engine. The device uses a reaction model to predict the amount of soot formed, which comprises several sub-models in which the reaction rate of the gas phase reaction is modeled by an Arrhenius equation. Using the Arrhenius equation, a prediction of a plurality of times of combustion for the work cycle is performed.

US 2011/0 079 194 A1 discloses a method of predicting the timing of combustion in an HCCI engine using an Arrhenius equation using only one combustion or fuel response parameter.

STATE OF THE ART

PATENT LITERATURE

• Patent Literature Example 1: JP 2009-168027 A
• Patent literature example 2: JP 2006-2637 A
• Patent Literature Example 3: JP 2008-101591 A
• Patent Literature Example 4: US 2010/0 058 832 A1
• Patent Literature Example 5: US 2011/0 079 194 A1

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

However, the auto-ignition timing or the timing of combustion in HCCI combustion is determined by the influence of a physical factor such as temperature distribution due to turbulent mixing and heat loss through the cylinder wall on the ignition delay time, which is determined by chemical reactions such as a low temperature oxidation reaction and a high temperature oxidation reaction is mastered. In addition, the chemical reaction rate in HCCI combustion is not only significantly influenced by the cylinder, but also, for example, by the equivalence ratio and the residual gas content.

However, in the HCCI internal combustion engines described in the above-mentioned Patent Literature Examples 1 to 3, the above-described physical factor and factors that greatly influence the chemical reaction rate are used in predicting the auto-ignition timing or the timing of the combustion in the HCCI combustion not considered. Therefore, for the HCCI internal combustion engines described in the above patent literature examples, it can be said that the prediction accuracy for the auto-ignition timing or the timing of the combustion in the HCCI combustion is not necessarily high.

Accordingly, it is an object of the present invention to provide a system and method for predicting the timing of combustion in an HCCI internal combustion engine, thereby improving the prediction accuracy for the auto-ignition timing or the timing of combustion in HCCI combustion over the prior art .

THE SOLUTION OF THE PROBLEM

According to the first aspect of the present invention, there is provided a system or method for predicting a timing of combustion of a mixture inside a cylinder for a combustion cycle of an HCCI internal combustion engine, comprising: determining at least two combustion reaction parameters from combustion reaction parameters that include a pressure state variable, which is determined based on a cylinder pressure inside the cylinder, a fuel mass fraction which is determined based on the state of the fuel mass and the air mass inside the cylinder, and a variable regarding the state of the burned gas which is based on the retention of the burned gas inside the cylinder is determined to include; Including the determined at least two combustion reaction parameters in an Arrhenius equation; and predicting a timing of the combustion for the combustion cycle using the Arrhenius equation, the timing of the combustion corresponding to a crank angle at which a mass fraction of the fuel burned is 50%.

According to the second aspect of the present invention, it is preferred that an exponent of each of the determined two combustion reaction parameters is a predetermined number.

According to the third aspect of the present invention, there is provided a system or method for predicting a timing of combustion of a mixture inside a cylinder for a cycle of an HCCI internal combustion engine, comprising: determining at least two combustion reaction parameters from combustion reaction parameters that include a pressure state variable, which is determined based on a cylinder pressure inside the cylinder, a fuel mass fraction determined based on the state of the fuel mass and the air mass inside the cylinder, and a variable regarding the state of the burned gas based on the retention of the burned gas determined inside the cylinder include; Determine at least one fuel condition parameter from fuel condition parameters, which is a mixed prediction variable for predicting the mixed condition of the fuel inside the cylinder, an injection completion time at which the injection of the fuel is completed, and a heat loss prediction variable for predicting heat loss due to heat transfer between a wall surface and the fuel in Include inside the cylinder; Plotting the determined combustion reaction and fuel condition parameters in an Arrhenius equation; and predicting a timing of the combustion for the combustion cycle using the Arrhenius equation, wherein the timing of the combustion corresponds to a crank angle at which a mass fraction of the burned fuel is 50%.

According to the fourth aspect of the present invention, it is preferred that an exponent of each of the determined combustion reaction and fuel state parameters is a predetermined number.

According to the fifth aspect of the present invention, it is preferable that the fuel mass fraction is an equivalence ratio or an inverse of the equivalence ratio.

According to the sixth aspect of the present invention, it is preferred that the state variable of the burned gas is a percentage of the mass of the residual gas with respect to the mass of the mixture in the cylinder.

According to the seventh aspect of the present invention, it is preferred that the mixed prediction variable is an engine speed of the engine or a reciprocal of the engine speed.

According to the eighth aspect of the present invention, it is preferred that the heat loss prediction variable be a difference between an exhaust gas temperature and an intake temperature.

TECHNICAL EFFECTS OF THE INVENTION

According to the first aspect, it is possible to predict the timing of the combustion more accurately than in the conventional technique, since arithmetic operations are performed using an Arrhenius equation to predict the timing of the combustion by taking combustion reaction parameters that affect a change in the timing of the combustion can in the equation. In addition, according to the first aspect, it is possible to predict the timing of the combustion even when the operating state of the HCCI engine changes, since arithmetic operations are performed using the Arrhenius equation, including at least two such combustion reaction parameters in the equation.

Accordingly, the first aspect makes it possible to improve the prediction accuracy for the timing of combustion in an HCCI engine over the prior art.

According to the second aspect, since the exponent of each of the combustion reaction parameters is a predetermined number, it is possible to predict the timing of the combustion more accurately. For example, if the exponents added to the respective combustion reaction parameters are experimentally determined in advance, it is possible to determine the timing of the combustion with high accuracy to predict by absorbing individual differences derived from HCCI internal combustion engine specifications.

According to the third aspect, it is possible to predict the timing of the combustion more accurately than in the conventional technique, since arithmetic operations are performed using an Arrhenius equation to predict the timing of the combustion by including combustion response and fuel state parameters that change the timing of combustion can affect the equation. Accordingly, the third aspect makes it possible to improve the prediction accuracy for the timing of combustion in an HCCI engine over the prior art.

According to the fourth aspect, since the exponent of each of the combustion reaction and fuel state parameters is a predetermined number, it is possible to predict the timing of the combustion more accurately. For example, if the exponents added to the respective combustion reaction and fuel state parameters are experimentally determined in advance, it is possible to predict the timing of the combustion with high accuracy by absorbing individual differences derived from specifications of HCCI internal combustion engines .

According to the fifth aspect, since a fuel equivalent ratio, which is a ratio between the stoichiometric air-fuel ratio and an actual air-fuel ratio, or a reciprocal of the equivalent ratio, which indicates an excess air ratio, is used as the fuel mass fraction, it is possible to To improve the prediction of the timing of combustion in HCCI combustion over the prior art, in which arithmetic operations of the Arrhenius equation are performed by measuring only the actual air-fuel ratio.

In the sixth aspect, the ratio of the residual gas retention with respect to the cylinder charge is used as the state variable of the burned gas. The residual gas contains nitrogen oxides and partially oxidized fuel, which is why the thermodynamic properties such as the heat capacity ratio and the temperature differ from those of the fresh or intake air. Thus, the amount of the residual gas can cause a temperature rise and a change in the chemical properties of the combustion inside the cylinder, which affects the timing of the combustion. Therefore, the sixth aspect makes it possible to predict the timing of the combustion more accurately since arithmetic operations of the Arrhenius equation are performed using the ratio of the residual gas retention to the cylinder charge.

In the seventh aspect, the engine speed or an inverse of the engine speed is used as a mixed prediction variable. It is known that the mixed state of the fuel affects the rate of combustion and the degree of mixing varies depending on the engine speed. Therefore, the seventh aspect makes it possible to improve the prediction accuracy of the timing of combustion since arithmetic operations of the Arrhenius equation are performed using the engine speed or its reciprocal to predict the mixed state of the fuel.

From the eighth point of view, a difference between the exhaust gas temperature and the intake temperature is used as the heat loss prediction variable. It is noted that the difference between the exhaust gas temperature and the intake temperature has a correlation with the distribution of the gas temperature inside the cylinder. It is also known that the distribution of the gas temperature generated inside the cylinder affects the timing of the combustion. Therefore, the eighth aspect makes it possible to improve the prediction accuracy because arithmetic operations of the Arrhenius equation are performed using the difference between the exhaust gas temperature and the intake temperature to take into account the influence of the distribution of the gas temperature generated inside the cylinder.

Figure list

• 1 FIG. 12 is a configuration diagram schematically illustrating a vehicle including a combustion timing prediction system according to a first embodiment of the present invention.
• 2nd 12 is a block diagram schematically illustrating the combustion timing prediction control according to the first embodiment of the present invention.
• 3rd FIG. 12 is a flowchart showing a processing flow of an ECU-executed timing control and ignition timing control processing performed by an ECU according to the first embodiment of the present invention.
• 4th FIG. 14 are views for comparing the accuracy of the timing of combustion with a conventional technology, wherein (a) illustrates the accuracy of the timing of combustion prediction by the combustion timing prediction system according to the first embodiment of the present invention, and FIG (b) represents the accuracy of the prediction of the timing of the combustion by a system of predicting the timing of the combustion according to the conventional technology.
• 5 FIG. 12 is a flowchart illustrating a processing flow executed by an ECU of the combustion timing prediction control and the ignition timing control according to a second embodiment of the present invention.
• 6 FIG. 11 is a flowchart illustrating an ECU processing processing routine of the timing prediction control and the ignition timing control according to a third embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

With reference to 1 to 6 Embodiments according to the present invention are described below.

First embodiment

With reference to 1 includes a vehicle 1 to which the present invention is assigned, an engine 2nd , an intake system 3rd , an exhaust system 4th , an EGR system 5 and an ECU 10th that works as a system for predicting the timing of combustion.

The motor 2nd includes, but is not limited to, a four-cylinder in-line gasoline engine, for example. With the engine 2nd it can be a so-called gasoline direct injection engine with an injection nozzle that is designed to inject fuel directly into a combustion chamber. The number of cylinders is not limited to four. The motor 2nd is not limited to a gasoline engine, but can be a diesel engine.

Moreover, the engine to which the present invention is associated is a homogeneous compression ignition internal combustion engine that enables homogeneous compression ignition combustion (referred to as "HCCI combustion"), that is, combustion caused by auto-ignition of an air-fuel mixture by compressing the air-fuel mixture in a cylinder 21 without one through a spark plug 20 generated spark is triggered.

Moreover, the engine 2nd designed to perform spark ignition (SI) combustion by forcibly igniting the air-fuel mixture with a spark plug 20 sparks generated. The engine thus enables 2nd switching between HCCI combustion and SI combustion in response to engine operating conditions determined by engine speed and load.

The intake system 3rd is with an intake passage 3a executed. The intake passage 3a is with a mechanical loader 30th and an intercooler 31 Mistake. The mechanical loader 30th is a mechanically operated supercharger and compresses the intake air to charge the engine by turning two rotors together in its housing. The mechanical loader 30th uses the engine as its source of power 2nd .

The intercooler 31 is on the downstream side of the mechanical supercharger with respect to the direction in which the intake air flows 30th arranged that he the intake air through the mechanical supercharger 30th was compressed, cools. This increases the degree of filling of the engine, which improves the intake efficiency.

The exhaust system 4th is with an exhaust passage 4a executed. The exhaust passage 4a is with a catalyst 40 Mistake. The catalyst 40 clean that from the engine 2nd emitted exhaust gas.

The EGR system 5 includes an EGR line 50 that with an EGR run 50a and an EGR valve 51 . The EGR passage 50a establishes a connection between the exhaust gas passage 4a and the intake passage 3a ready to some of the exhaust gas passing through the exhaust passage 4a runs.

The EGR valve 51 is in the EGR passage in such a way 50a built in that there is an EGR amount, which is the amount of exhaust gas that goes to the intake passage 3a to be returned, indicates, regulated. The opening / closing of the EGR valve 51 is through the ECU 10th controlled.

The ECU 10th includes a microcomputer having, for example, a CPU, a RAM, a ROM, an input / output interface and the like, the CPU performing signal processing according to programs previously stored in the ROM using a temporary storage function of the RAM . Various control parameters, various characteristics and the like are stored in advance in the ROM.

Also connected to the input ports of the ECU 10th various sensors such as an air quantity sensor 101 , an intake temperature sensor 102 , an intake pressure sensor 103 , an intake O ₂ sensor 104, a cylinder pressure sensor 105 , an exhaust gas temperature sensor 106 , an air / fuel sensor (A / F sensor) 107, a crank angle sensor 180 and a coolant temperature sensor 181 connected.

The airflow sensor 101 is in that part of the intake passage in such a way 3a that is on the upstream side of the mechanical supercharger with respect to the direction in which the intake air flows 30th is installed that it detects the amount of intake air. The intake temperature sensor 102 is in that part of the intake passage in such a way 3a that, in relation to the direction in which the intake air flows, on the downstream side of the charge air cooler 31 is installed so that it detects an intake air temperature indicating the temperature of the intake air (hereinafter simply referred to as "intake temperature").

The intake pressure sensor 103 is in that part of the intake passage in such a way 3a that, in relation to the direction in which the intake air flows, on the downstream side of the charge air cooler 31 is installed, that it detects an intake air pressure that indicates the pressure of the intake air. The suction O ₂ sensor 104 is in that part of the suction passage in such a manner 3a that, in relation to the direction in which the intake air flows, on the downstream side of the charge air cooler 31 located, built in that it is the oxygen concentration of the gas entering a cylinder 21 is admitted.

The cylinder pressure sensor 105 is in a cylinder head, not shown, with the cylinder 21 is built in to an internal cylinder pressure, which is a pressure in the cylinder 21 indicates to capture. The exhaust gas temperature sensor 106 is in that part of the exhaust passage in such a way 4a that is on the upstream side of the catalyst with respect to the direction in which the exhaust gas flows 40 is installed so that it detects an exhaust gas temperature indicating the temperature of the exhaust gas (hereinafter simply referred to as "exhaust gas temperature").

The air / fuel sensor 107 is in that part of the exhaust passage 4a that is on the upstream side of the catalyst with respect to the direction in which the exhaust gas flows 40 is located, installed and provides linear characteristics that are proportional to actual values of the air / fuel ratio of the exhaust gas. The air / fuel sensor 107 Detects actual values of the air / fuel ratio of the exhaust gas on the basis of the oxygen concentration in the exhaust gas.

The crank angle sensor 180 is in the engine 2nd built in to a crank angle of the engine crankshaft 2nd capture. The coolant temperature sensor 181 is in the engine 2nd built in to the temperature of the coolant for the engine 2nd , that is, the coolant temperature.

There are also various items of equipment such as the EGR valve 51 , Spark plugs 20 and injectors 23 to the ECU output terminals 10th connected. The ECU 10th controls these various pieces of equipment based on the input values of the various sensors previously described.

The ECU 10th is configured to perform, for example, control of the prediction of the combustion time to the time of the combustion in the HCCI internal combustion engine 2nd to predict. Moreover, the ECU 10th configured to control the ignition timing to control an injector based on the timing of the combustion predicted by the control to predict the timing of combustion 23 and a spark plug 20 to enable HCCI combustion at an appropriate time.

Referring now to 2nd the combustion timing prediction control and the ignition timing control performed by the ECU 10th are described.

As in 2nd shown the ECU calculates 10th based on the detection result from the crank angle sensor 180 is entered, the engine speed Ne. The ECU also calculates 10th based on the accelerator position input from an accelerator position sensor, the engine load.

The ECU 10th calculated on the basis of the engine speed Ne, the engine load and by the air quantity sensor 101 detected intake air amount a basic fuel injection amount. The ECU also calculates 10th based on the base fuel injection amount and the intake air amount, the equivalence ratio φ (the Greek letter phi), which is the ratio of the air-fuel ratio of the engine 2nd admixed mixture is defined to the stoichiometric air-fuel ratio.

The ECU 10th calculated from the equivalence ratio based on the intake air amount, the oxygen concentration detected by the intake O ₂ sensor 104, and the actual air-fuel ratio by the air / fuel sensor 107 is determined an amount of the EGR gas generated by the EGR system 5 to be returned to the engine intake side (hereinafter referred to as "external EGR gas").

It should be noted that the ratio of oxygen (O ₂ ), nitrogen (N ₂ ) and carbon dioxide (CO ₂ ) in the air is well known, since these are the main gases in the air. For this reason, the oxygen concentration of the intake air quantity is caused by the air quantity sensor 101 is well known. So the ECU 10th the external EGR quantity with the intake O ₂ sensor 104 by detecting the oxygen concentration in the amount of the intake air containing exhaust gas, its oxygen concentration by the air / fuel sensor 107 is determined.

The ECU 10th calculated using the equation of state for the gas based on the cylinder pressure and the exhaust gas temperature during the opening of an intake valve by the cylinder pressure sensor 105 and the exhaust gas temperature sensor 106 and the volume of a combustion chamber, when the cylinder pressure and the exhaust gas temperature are detected, the mass of the residual gas as an amount of the residual gas. The equation of state for the gas is expressed as "PV = mRT", where "P" is the cylinder pressure, "V" is the volume of a combustion chamber, "m" is the mass of the residual gas, "R" is the gas constant of the residual gas, and "T" is the exhaust gas temperature, which roughly corresponds to the cylinder temperature.

The ECU 10th calculates the residual gas retention in a cylinder X _rg based on the amount of external EGR gas and the amount of residual gas. In particular, the ECU calculates 10th the residual gas retention X _rg , which is the ratio of the residual gas amount to the mixture amount in the cylinder, which is the total of the amount of the external residual gas, the residual gas amount, the intake air amount and the basic _{fuel injection} amount.

The ECU 10th calculates the cylinder pressure P _{cyl_10BTDC} based on the amount of external EGR gas, the intake air quantity, the basic _{fuel injection quantity} , the residual gas quantity and the cylinder _pressure , where "cyl" indicates something in a cylinder, and 10BTDC the time at a crankshaft angle of 10 ° before the upper one Indicates dead center of compression.

In particular, the ECU calculates 10th the cylinder pressure P _{cyl_10BTDC} when the cylinder pressure is detected by the cylinder _{pressure sensor} , as mentioned below. Assuming a polytrophic process, the ECU calculates 10th the cylinder pressure P _{cyl_10BTDC} based on the following equation (1) using the cylinder pressure P _{cyl_ivc} and the volume of the combustion chamber V _{cyl_ivc} when the intake valve closes and the volume V _{cyl_10BTDC} at 10 ° before compression top dead center, where "ivc" is the moment of closing the intake valve. In addition, "n" in the following equation indicates the polytrophic index. $$P_{cyl\_\mathrm{10th}BTD\mathrm{C.}}=P_{cyl\_ivc}{\left(V_{cyl\_ivc}/V_{cyl\_\mathrm{10th}BTD\mathrm{C.}}\right)}^n$$

In addition, the ECU 10th as in the above-mentioned calculation of the cylinder pressure P _{cyl_10BTDC} using the following equation (2), calculate the cylinder _temperature T _{cyl_10BTDC} . $$T_{cyl\_\mathrm{10th}BTD\mathrm{C.}}=T_{cyl\_ivc}{\left(V_{cyl\_ivc}/V_{cyl\_\mathrm{10th}BTD\mathrm{C.}}\right)}^{n-1}$$

The ECU 10th the cylinder _temperature T _{cyl_ivc} in the above equation (2) after determining the cylinder pressure P _{cyl_ivc} when closing the intake valve, the volume of a combustion chamber V _{cyl_ivc} when closing the intake valve, the mass of the _{mixed cylinder charge of} a mixture m, and the gas constant R of the mixture Find out from the equation of state for the gas, ie, "P _{cyl_ivc} V _{cyl_ivc} = mRT".

After determining the average molecular mass of the mixture from the molar proportions of the component of the external gas, the component of the residual gas, the component of the intake air, the component of the fuel, and the other components, the gas constant of the mixture can be determined by dividing the universal gas constant R, ie , R = 8.3144621 (75) JK ^-1 mol ^-1 , obtained from the average molecular mass of the mixture.

In addition, the ECU 10th the cylinder pressure P _{cyl_ivc} and the cylinder _temperature T _{cyl_ivc} mentioned above when the cylinder _{pressure sensor} 105 is not used by determining calculations using each of the following equations.

$$P_{cyl\_ivc}=\mathrm{I.}\cdot M_{air}{}^J\cdot P_{in\_ivc}{}^K$$

$$T_{cyl\_ivc}=L\cdot T_{in\_ivO}+N\cdot T_{ex\_ivO}+Q\cdot T_{water}$$

In the above equation (3), M _{air is} the intake air amount, that is, that by the air amount sensor 101 mass air _flow detected, and P _{in_ivc is} the intake air _pressure when the intake valve closes. In the above equation (4), T _{in_ivo is} the cylinder temperature when the intake valve closes, T _{ex_ivo is} the exhaust gas temperature when the intake valve closes, and T _{water is} that by the coolant temperature sensor 181 detected coolant temperature.

Furthermore, the values of the indices J and K in the above equation (3) are determined by a multivariate regression analysis of data, which takes into account individual differences arising from the specifications of the engine 2nd were derived, were determined experimentally. Moreover, similarly to the above indexes J and K, the values of the indexes I, L, N and Q in the above equations (3) and (4) are determined by a multivariate regression analysis of data, which is determined in advance taking into account individual differences the specifications of the engine 2nd were derived, were determined experimentally.

Furthermore, the ECU says 10th the time of combustion CA50 in the engine 2nd by using the Arrhenius equation, taking a combustion reaction parameter (of combustion reaction parameters) and a fuel state parameter (of fuel state parameters) as their pre-exponential factor. According to the present embodiment, a crank angle (CA) with a mass fraction of combustion of 50% is treated as the time of combustion CA50.

The time of combustion in an HCCI internal combustion engine such as the engine 2nd is dominated by the influence of a physical factor such as the temperature distribution due to turbulent mixing and the heat loss through the cylinder wall on the ignition delay time, which is speed-determined by chemical reactions such as a low temperature oxidation reaction and a high temperature oxidation reaction. Accordingly, for an accurate prediction of the time of combustion, there is a need to take into account the physical factor and factors that affect the chemical reaction rate.

Therefore, in order to improve the accuracy of predicting the timing of combustion, the present embodiment has the combustion reaction parameter (s) and the fuel state parameter (s) as the pre-exponential factor in the Arrhenius equation, which is a formula for the temperature dependence of reaction rates, added.

These combustion reaction _{parameters are} the cylinder pressure P _{cyl_10BTDC} , which is determined by equation (1) as a pressure state variable based on the cylinder pressure, the residual gas _fraction X _rg , which is a variable with regard to the burned gas based on the retention of the burned gas inside of the cylinder 21 and the equivalence ratio φ determined based on the basic fuel injection amount and the intake air amount. The equivalence ratio φ corresponds to a fuel mass fraction based on the state of the fuel mass and the air mass inside the cylinder 21 is determined. The mass fraction can be a reciprocal of the equivalence ratio φ, which indicates a factor of the excess air.

These fuel state parameters are a reciprocal of the engine speed Ne, which is a mixed prediction variable for predicting the mixed state of the fuel inside the cylinder 21 represents a time EoI of the completion of the injection, a difference (T _ex - T _in ) between the exhaust gas temperature T _ex and the intake temperature T _in , which is a heat loss prediction variable for predicting the heat transfer between a wall surface and the fuel inside the cylinder 21 heat loss caused. Note that the mixed prediction variable can be represented by the engine speed Ne.

In particular, the ECU determines 10th the timing of the combustion CA50 by calculating the following equation (5) based on each of the combustion reaction parameters and the fuel _{state parameters} listed above and the cylinder _temperature T _{cyl_10BTDC calculated} by the aforementioned equation (2).

$$\mathrm{C.}A50=A\cdot P_{cyl\_10BTD\mathrm{C.}}{}^B\cdot {\phi }^{\mathrm{C.}}\cdot X_{rG}{}^D\cdot {\left(Ne\right)}^F\cdot {\left(T_{ex}-T_{in}\right)}^G\cdot EO{l}^H\cdot exp\left(-E/R{T}_{cyl\_10BTD\mathrm{C.}}\right)$$

In equation (5), R is the gas constant of the mixture and A is the index, which is determined by a multivariate regression analysis of data, which takes into account individual differences arising from the specifications of the engine 2nd were derived, were determined experimentally.

In equation (5), an exponent of each of the combustion reaction parameters is a predetermined number B or C or D, and an exponent of each of the fuel state parameters is a predetermined number F or G or H. These exponents B, C, D and F, G , H are just like the exponent A numbers, which are determined by a multivariate regression analysis of data, which in advance taking into account individual differences arising from the specifications of the engine 2nd were derived, were determined experimentally.

The ECU also compares 10th the combustion timing CA50 determined by the equation (5) with the target combustion timing obtained from a target combustion timing characteristic and determines the fuel injection amount, the fuel injection timing, the ignition timing, and the number of times of the ignition based on this comparison result. The target ignition timing characteristic is a characteristic that is designed to determine a target ignition timing using, for example, the engine speed Ne as a parameter and in the ROM of the ECU 10th was stored after experimentally determining the relationship between the engine speed Ne and the time of combustion.

The target combustion time is expressed by the crank angle and represents a target crank angle at which there is a mass fraction of the combustion of 50%. Thus, a target value of the crank angle CA50 will be treated as the target combustion timing CA50 below.

In particular, the ECU determines 10th the fuel injection amount, the fuel injection timing, the ignition timing and the number of times of ignition depending on whether or not the timing of the combustion CA50 matches the target ignition timing CA50. The case in which the time of combustion CA50 coincides with the target combustion time CA50 includes the case in which the time of combustion CA50 exactly coincides with the target combustion time CA50 and that in which the time of combustion CA50 falls within a predetermined tolerance range of the target combustion time CA50 falls. The predetermined tolerance range depends on the specification of the motor 2nd arbitrarily determined and is, for example, ± 1 ° CA.

For example, when the combustion timing CA50 matches the target combustion timing CA50, the ECU controls 10th along with the fuel injection amount, the fuel injection timing, the ignition timing and the number of times of ignition that result from one Fuel injection quantity map, a fuel injection timing map, an ignition timing map, and the number of times ignition map are determined to determine the operation of the injector 23 and the spark plug 20 to perform fuel injection and ignition.

On the other hand, when the combustion timing CA50 does not coincide with the target combustion timing CA50, the ECU executes 10th Corrections to the fuel injection amount, the fuel injection timing, the ignition timing and the number of times of ignition by increasing or decreasing the fuel injection amount and / or advancing or retarding the timing of the ignition. In this case, the ECU controls 10th together with the corrected fuel injection amount, the corrected fuel injection timing, the corrected ignition timing, and the corrected number of times of the ignitions, the operation of the injector 23 and the spark plug 20 to perform fuel injection and ignition.

Referring now to 3rd An example program for performing the control of predicting the timing of combustion and controlling the timing of ignition is described. This program for performing the control of predicting the timing of combustion and the timing of ignition is executed by the ECU 10th executed at predetermined intervals.

As in 3rd is illustrated by the ECU 10th based on the input of the detected result from the crank angle sensor 180 determines whether or not the time is favorable for various arithmetic operations performed in the combustion timing prediction control and the ignition timing control and for measurements by various sensors (step S1 ). If it is determined that the time for these various arithmetic operations and for these measurements by various sensors is not favorable, the ECU repeats 10th processing at step S1 .

On the other hand, if it is determined that the time for these various arithmetic operations and for these measurements by various sensors is favorable, the ECU detects the engine operating conditions expressed by the engine speed Ne and the accelerator pedal position (step S2 ).

Next, the ECU detects 10th various detected values that are used in the control for predicting the timing of combustion and the control of the ignition timing, such as the intake air quantity, the intake temperature T _in , the exhaust gas temperature T _ex and the coolant temperature T _water (step S3 ).

Then the ECU calculates 10th based on the engine speed Ne, the engine load and the intake air amount, the basic fuel injection amount (step S4 ). Next the ECU calculates 10th using the equation (5) the time of combustion CA50 (step S5 ).

Then the ECU determines 10th whether or not the timing of the combustion CA50 coincides with the target combustion timing CA50 (step S6 ). As mentioned above, the determination of whether or not the timing of combustion CA50 coincides with the target combustion timing CA50 is determined by determining whether the timing of combustion CA50 exactly matches the target combustion timing CA50 or the timing of combustion CA50 falls within the tolerance range of the target combustion timing CA50.

When the combustion time CA50 coincides with the target combustion time CA50, the program ends. In this case, the ECU controls 10th along with the fuel injection amount, the fuel injection timing, the ignition timing, and the number of times of ignition determined from the fuel injection quantity map, the fuel injection timing map, the ignition timing map, and the number of times ignition, the operation of the injector 23 and the spark plug 20 to perform fuel injection and ignition.

On the other hand, when the combustion timing CA50 does not coincide with the target combustion timing CA50, the ECU determines 10th whether the timing of combustion CA50 is greater than the target combustion timing CA50, that is, whether or not the timing of combustion CA50 is delayed from the target combustion timing CA50 (step S7 ).

When the combustion timing CA50 is delayed from the target combustion timing CA50, the ECU takes 10th advance the time of combustion CA50 (step S8 ). Specifically, the fuel injection amount, the fuel injection timing, the ignition timing, and the number of times of ignition are increased by, for example, increasing the fuel injection amount and Corrected the advance of the ignition timing so that the time of combustion CA50 is brought forward. This brings the time of combustion CA50 forward.

On the other hand, if the combustion timing CA50 is not delayed from the target combustion timing CA50, the ECU decelerates 10th the time of combustion CA50 (step S9 ). Specifically, the fuel injection amount, the fuel injection timing, the ignition timing and the number of times of ignition are corrected, for example, by reducing the fuel injection amount and retarding the ignition timing so that the timing of the combustion CA50 is delayed. This delays the time of combustion CA50.

The correction values for the fuel injection quantity and the ignition timing, which are in step S8 and step S9 used are determined experimentally and as correction characteristics for the fuel injection amount and the ignition timing in the ROM of the ECU 10th saved.

Then after in step S8 or step S9 such corrections to the timing of combustion CA50 have been made, the ECU calculates 10th in step S5 again the time of combustion CA50 after the correction and determines whether or not the time of combustion CA50 after the correction matches the target combustion time CA50. In this way, the time of combustion CA50 after the correction is corrected until the time of combustion CA50 after the correction coincides with the target combustion time CA50.

Referring now to 4th the prediction accuracy of the combustion timing prediction system CA50 according to the present embodiment will be described. 4th FIG. 14 shows views to compare the prediction accuracy with which the CA50 combustion timing is predicted using equation (5) with the prediction accuracy with which the CA50 combustion timing is predicted using the conventional Arrhenius equation.

In 4 (a) The horizontal line labeled "CA50 calculated in degrees after top dead center" shows the time of combustion CA50 that is predicted using equation (5), and the vertical line labeled "CA50 measured in degrees after top dead center" shows that actually measured time of combustion CA50.

Moreover, in 4 (b) the horizontal line labeled "CA50 calculated in degrees after top dead center" indicates the time of combustion CA50 that is predicted using the conventional Arrhenius equation, and the vertical line labeled "CA50 measured in degrees after top dead center" actually measured time of combustion CA50. Each of these times of combustion CA50 is an event that occurs after top dead center.

Moreover, are 4 (a) and 4 (b) Diagrams which each indicate the correlation of the predicted time of combustion CA50 with the actually measured time of combustion CA50. In each diagram, the greater the correlation between the predicted timing of combustion CA50 and the actually measured timing of combustion CA50 (a linear function with slope "1"), the closer the solid line is to each of the points shown, which indicates that the prediction accuracy of the time of combustion CA50 is high.

The degree of this correlation can be indicated by the coefficient of determination R ² (R squared). The determination coefficient R ² is closer to “1”, the stronger the correlation between the estimated time of combustion CA50 and the actually measured time of combustion CA50. Thus, the higher the prediction accuracy of the estimated time of combustion CA50, the closer the determination coefficient R ² is to “1”.

Now the coefficient of determination is R ² for the in 4 (a) shown diagram "0.9675", and it is closer to "1" than the coefficient of determination R ^{2 is} equal to 0.698 in the in 4 (b) shown diagram. So show 4 (a) and 4 (b) clearly, that the prediction accuracy of the estimated timing of combustion CA50 using equation (5) is higher than the prediction accuracy of the estimated timing of combustion CA50 using the conventional Arrhenius equation.

Hence the system for predicting the timing of combustion according to the present embodiment have a higher prediction accuracy of the timing of combustion CA50 than the system for predicting the timing of combustion using the conventional Arrhenius equation.

As mentioned above, the combustion timing prediction system according to the present embodiment can predict the combustion timing CA50 more accurately than the prior art because arithmetic operations are performed after the combustion reaction parameters and the fuel state parameters that change the timing of the combustion CA50 in the Arrhenius equation.

The combustion timing prediction system according to the present embodiment performs arithmetic operations after including a plurality of combustion reaction parameters and a plurality of fuel state parameters in the Arrhenius equation, so that it can accurately predict the combustion timing CA50 even if the operating condition of the Motors 2nd changed.

In this way, the combustion timing prediction system according to the present embodiment can improve the accuracy of the auto-ignition timing or CA50 combustion timing that takes place in HCCI combustion compared to the prior art.

Moreover, the combustion timing prediction system according to the present embodiment can more accurately predict the combustion timing CA50 because each of the combustion reaction parameters and each of the fuel state parameters has the predetermined exponents.

If the exponents of each of the combustion reaction parameters and each of the fuel state parameters are experimentally determined in advance, the system can predict the timing of combustion CA50 with good accuracy by making individual differences based on engine specifications 2nd be derived, absorbed.

Moreover, the combustion timing prediction system according to the present embodiment _uses the residual gas _portion X _rg as the state variable of the burned gas. The residual gas contains nitrogen oxides and partially oxidized fuel, so that the thermodynamic properties such as the heat capacity ratio and the temperature differ from those of the fresh or intake air.

Thus, the amount of residual gas can cause a temperature rise and a change in the chemical properties of the combustion inside the cylinder 21 cause, which affects the time of combustion CA50. Therefore, the combustion timing prediction system improves the prediction accuracy of the combustion timing CA50 since arithmetic operations of the Arrhenius equation are performed using the residual gas _fraction X _rg .

In addition, the combustion timing prediction system according to the present embodiment uses the engine speed Ne as a mixed prediction variable. It is known that the mixed state of the fuel affects the combustion speed, and that the degree of mixing is different depending on the engine speed Ne.

Therefore, the combustion timing prediction system more accurately predicts the combustion timing CA50 because arithmetic operations of the Arrhenius equation are performed using the engine speed to predict the mixed state of the fuel.

Moreover, the combustion timing prediction system according to the present embodiment uses a difference between the exhaust gas temperature T _ex and the intake temperature T _in as a heat loss prediction variable. It is noted that the difference between the exhaust gas temperature T _EX and the intake temperature T _in a correlation with the distribution of the gas temperature inside the cylinder 21 having. It is also known that the distribution of the gas temperature inside the cylinder 21 is generated, influences the time of combustion CA50.

Therefore, the combustion timing prediction system according to the present embodiment can improve the prediction timing of the combustion timing CA50 because arithmetic operations of the Arrhenius equation using the difference between the exhaust gas temperature T _ex and the intake temperature T _in to the influence of the inside of the cylinder 21 to take into account the generated distribution of the gas temperature.

In the present embodiment, all of the combustion reaction parameters and all of the fuel state parameters are used to predict the timing of the combustion, but the present invention is not limited to this. For example, if an engine is to be used in which the distribution of the temperature and / or the distribution of the equivalence ratio inside the cylinder 21 are relatively small, one of the following equations (6) to (8), after eliminating the influence of the distribution of the temperature and / or the distribution of the equivalence ratio inside the cylinder 21 given from equation (5) can be used to predict the timing of combustion CA50.

$$\mathrm{C.}A50=A\cdot P_{cyl\_10BTD\mathrm{C.}}{}^B\cdot {\phi }^{\mathrm{C.}}\cdot X_{rG}{}^D\cdot {\left(Ne\right)}^F\cdot EO{l}^H\cdot exp\left(-E/R{T}_{cyl\_10BTD\mathrm{C.}}\right)$$

$$\mathrm{C.}A50=A\cdot P_{cyl\_10BTD\mathrm{C.}}{}^B\cdot {\phi }^{\mathrm{C.}}\cdot X_{rG}{}^D\cdot {\left(1/Ne\right)}^F\cdot {\left(T_{ex}-T_{in}\right)}^F\cdot exp\left(-E/R{T}_{cyl\_10BTD\mathrm{C.}}\right)$$

$$\mathrm{C.}A50=A\cdot P_{cyl\_10BTD\mathrm{C.}}{}^B\cdot {\phi }^{\mathrm{C.}}\cdot X_{rG}{}^D\cdot {\left(1/Ne\right)}^F\cdot exp\left(-E/R{T}_{cyl\_10BTD\mathrm{C.}}\right)$$

Moreover, if an engine 2nd where the influence of the turbulence / mixture is small, the following equation (9), in which the term dependent on the engine speed Ne is omitted, can be used to predict the timing of the combustion CA50.

$$\mathrm{C.}A50=A\cdot P_{cyl\_10BTD\mathrm{C.}}{}^B\cdot {\phi }^{\mathrm{C.}}\cdot X_{rG}{}^D\cdot exp\left(-E/R{T}_{cyl\_10BTD\mathrm{C.}}\right)$$

Equations (6) through (9) above provide exemplary changing variations in combustion reaction parameters and fuel condition parameters that are given in Equation (5) for different engine specifications 2nd are used, but the modifications are not so limited.

For example, the combustion timing prediction system according to the present embodiment in Equation (5) may use at least two combustion _{reaction parameters selected} from the cylinder pressure P _{cyl_10BTDC} , the residual gas _content X _rg, and the equivalence _ratio φ.

Furthermore, the system for predicting the timing of the combustion according to the present embodiment in equation (5) can have at least one combustion _{reaction parameter selected} from the cylinder pressure P _{cyl_10BTDC} , the residual gas _content X _rg and the equivalence _ratio φ, and at least one fuel _{condition parameter} derived from the engine speed Use Ne, the time Eol when the fuel injection is completed and the difference (T _ex - T _in ) is selected.

Furthermore, the combustion timing prediction system according to the present embodiment corrects the ignition timing and the number of times of ignition to advance or retard the combustion timing CA50, but it can be modified to be only the fuel injection amount and the fuel injection timing corrected.

Second embodiment

Next up 5 used to describe a second embodiment of the present invention.

The present embodiment differs from the previous first embodiment only in a part of the processing of the control for predicting the timing of combustion and the control of the ignition timing, while the rest of the construction and the processing are the same as those in the first embodiment. Therefore, the description of the same structure and processing as those of the first embodiment will be omitted below, and only the part different from the first embodiment will be described.

In the combustion timing prediction control and the ignition timing control according to the first embodiment, the ECU repeats 10th correcting the timing of combustion CA50 until the timing of combustion CA50 after the forward correction in step S8 or the delayed correction in step S9 from 3rd matches the target combustion time CA50.

On the other hand, the ECU repeats 10th of the present embodiment does not correct the combustion timing CA50, but rather performs the correction for the combustion timing CA50 in step S18 or S19 only once.

In particular, ends like in 5 shown the program after the ECU 10th in the present embodiment, the advancement correction in step S18 performed. The program also ends after the ECU 10th the delayed correction in step S19 performed.

In addition, the ECU 10th the advance correction for the time of combustion CA50 in step S18 referring to, for example, a correction characteristic that defines a relationship between a difference between the combustion timing CA50 and the target combustion timing CA50 and the corresponding value of increasing the fuel injection amount and the corresponding advance amount of the ignition timing only once. The above-mentioned correction characteristic with previously experimentally determined data is in the ROM of the ECU 10th saved.

In addition, the ECU 10th like processing in step S18 the retarding correction for the time of combustion CA50 in step S19 referring to, for example, a correction characteristic defining a relationship between a difference between the combustion timing CA50 and the target combustion timing CA50 and the corresponding value of the decrease in the fuel injection amount and the corresponding value of the retardation amount of the ignition timing only once.

Since, moreover, the content in each of the steps S11 to S19 , in the 5 are shown, the same as the content in the corresponding steps S1 to S9 in 3rd , these steps are not described in the present embodiment.

As mentioned above, the combustion timing prediction system according to the present embodiment provides the following technical effect in addition to the technical effects provided by the first embodiment. The processing load of the ECU 10th is decreased because the combustion timing prediction system according to the present embodiment, the combustion timing CA50 in step S18 and step S19 corrected only once without repeating the correction of the time of combustion CA50.

Third embodiment

Next up 6 used to describe a third embodiment of the present invention.

According to the above-mentioned first embodiment, the fuel injection amount, the fuel injection timing, the ignition timing and the number of times of ignition are corrected by increasing or decreasing the fuel injection amount and advancing or retarding the ignition timing so that the timing of the combustion CA50 can reach an optimal timing.

When such correction corrects the timing of combustion CA50 to the optimum timing, the burning time is shortened, causing noise and a problem with the strength of the engine. For example, an increase in the cylinder pressure rise rate dP / dCA causes the shortened burning time.

Now, according to the present embodiment, the burning time CA10 to CA90, the maximum cylinder pressure Pmax, and the pressure increase rate dP / dCA are predicted in the same manner as in the combustion timing prediction method according to the previously described first embodiment. The burning time CA10 to CA90 is the time or crank angle from the moment of a mass fraction of combustion of 10% to the moment of a mass fraction of combustion of 90% inside the cylinder.

Furthermore, the ECU reduces 10th the fuel injection amount and retards the ignition timing based on the predicted pressure rise rate dP / dCA. This causes a decrease in cylinder pressure, which restricts an increase in the rate of pressure increase dP / dCA.

Referring now to 6 describes a program for performing the prediction of the timing of combustion and the control of the ignition timing. Processing step 21 until step 25th , in the 6 is shown is the same as the processing of step 1 until step 5 used in the description of the first embodiment 3rd is shown. Therefore, only the part of the processing that is different from the first embodiment will be described.

As in 6 shown the ECU determines 10th whether the in step 25th calculated time of combustion CA50 coincides with a target combustion time CA50 or not (step S26 ). The determination of whether or not the timing CA50 coincides with the target combustion timing CA50 is made in the same manner as in the first embodiment.

If the ECU 10th determines that the time of combustion CA50 coincides with the target combustion time CA50, the program goes to step S28 over. On the other hand, when the combustion timing CA50 does not coincide with the target combustion timing CA50, the ECU corrects 10th the time of combustion CA50 (step S27 ) and the program returns to step S25 back.

To correct the timing of combustion CA50, the ECU increases or decreases 10th for example, the amount of fuel injection and advances or retards the ignition timing. This leads to a correction in order to advance or delay the time of combustion CA50.

In step S28 the ECU calculates 10th the pressure increase rate dP / dCA. It is then determined whether or not the calculated pressure increase rate dP / dCA is less than a target pressure increase rate (step S29 ). The target pressure increase rate is a pressure increase rate that enables the burn time to be prevented from becoming short, and this pressure increase rate has been found experimentally and in the ROM of the ECU 10th saved.

If the ECU 10th determines that the pressure increase rate dP / dCA is less than the target pressure increase rate, the program ends. On the other hand, if the pressure increase rate dP / dCA is not less than the target pressure increase rate or equal to or greater than the target pressure increase rate, the ECU performs 10th control to decrease cylinder pressure (step S30 ), and the program returns to step S28 back.

The ECU acts as a control for reducing the cylinder pressure 10th for example, control to delay the timing of combustion CA50 and reduce the fuel injection amount. This reduces the cylinder pressure.

Moreover, auto-ignition in HCCI combustion and knock in the spark-ignition internal combustion engine can be considered the same event. Therefore, the method of predicting the timing of combustion described in connection with each of the above embodiments is applicable to the knock control for a spark ignition engine. For example, in such a knock control, instead of predicting the timing of the combustion, it is predicted whether knocking occurs or not. In addition, the method of predicting the timing of combustion may be applicable to the pre-ignition control that may occur at the time of charging. In this case, instead of predicting the timing of the combustion, whether or not pre-ignition occurs is predicted.

Although one embodiment of the present invention has been described, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the present invention. All such modifications and their equivalents are intended to be covered by the following claims, which are described in the claims.

Reference list

1

vehicle

2nd

Engine (HCCI internal combustion engine)

5

EGR system

10th

ECU

20

spark plug

21

cylinder

23

Injector

30th

mechanical loader

101

Air flow sensor

102

Intake temperature sensor

103

Intake pressure sensor

104

Intake O ₂ sensor

105

Cylinder pressure sensor

106

Exhaust gas temperature sensor

107

Air / fuel sensor

180

Crank angle sensor (A / F sensor)

181

Coolant temperature sensor

Claims (12)

A system for predicting a timing of combustion of a mixture inside a cylinder (21) for a combustion cycle of an HCCI internal combustion engine (2), comprising: determining at least two combustion _{reaction parameters} from combustion _{reaction parameters} , which is a pressure state _variable (P _{cyl_10BTDC} ), which is based on a cylinder pressure inside the cylinder (21) is determined, a fuel mass fraction (φ, φ ^-1 ) determined based on the state of the fuel mass and the air mass inside the cylinder (21), and a variable regarding the state of the burned gas ( X _rg ), which is determined based on the retention of the burned gas inside the cylinder (21); Including the determined at least two combustion reaction parameters in an Arrhenius equation; and predicting a time of combustion (CA50) for the combustion cycle using the Arrhenius equation, the time of combustion (CA50) corresponding to a crank angle (CA) at which a mass fraction of the fuel burned is 50%. System according to Claim 1 , wherein an exponent of each of the determined at least two combustion reaction parameters is a predetermined number (B or C or D). A system for predicting a timing of combustion of a mixture inside a cylinder (21) for a cycle of an HCCI internal combustion engine (2), comprising: determining at least two combustion _{reaction parameters} from combustion _{reaction parameters} that are a pressure state _variable (P _{cyl_10BTDC} ), which is based on a cylinder pressure inside the cylinder (21) is determined, a fuel mass fraction (φ, φ ^-1 ) which is determined based on the state of the fuel mass and the air mass inside the cylinder (21), and a variable regarding the state of the burned gas ( X _rg ), which is determined based on the retention of the burned gas inside the cylinder (21); Determining at least one fuel condition parameter from fuel condition parameters that include a mixed prediction variable (Ne, Ne ^-1 ) for predicting the mixed condition of the fuel inside the cylinder (21), an injection completion timing (Eol) at which the fuel injection is completed, and a heat loss prediction variable ( T _ex - T _in ) for predicting heat loss due to heat transfer between a wall surface and the fuel inside the cylinder (21); Plotting the determined combustion reaction and fuel condition parameters in an Arrhenius equation; and predicting a time of combustion (CA50) for the combustion cycle using the Arrhenius equation, the time of combustion (CA50) corresponding to a crank angle (CA) at which a mass fraction of the fuel burned is 50%. System according to Claim 3 , wherein an exponent of each of the determined combustion reaction and fuel condition parameters is a predetermined number (B or C or D, F or G or H). System according to one of the Claims 1 to 4th , wherein the fuel mass fraction is an equilibrium ratio or a reciprocal of the equivalence ratio (φ, φ ^-1 ). System according to one of the Claims 1 to 5 , the variable regarding the condition of the burned gas being a percentage of the residual gas mass in relation to the mixture mass in the cylinder (X _rg ). System according to one of the Claims 3 to 6 , wherein the mixed prediction variable is an engine speed of the engine (2) or a reciprocal of the engine speed (Ne, Ne ^-1 ). System according to one of the Claims 3 to 7 , the heat loss prediction variable being a difference between an outlet temperature and an intake air temperature (T _ex - T _in ). A method of predicting a timing of combustion of a mixture inside a cylinder (21) for a combustion cycle of an HCCI internal combustion engine (2), comprising: determining at least two combustion _{reaction parameters} from combustion _{reaction parameters} that are a pressure state _variable (P _{cyl_10BTDC} ), which is based on a cylinder pressure inside the cylinder (21) is determined, a fuel mass fraction (φ, φ ^-1 ) determined based on the state of the fuel mass and the air mass inside the cylinder (21), and a variable regarding the state of the burned gas ( X _rg ), which is determined based on the retention of the burned gas inside the cylinder (21); Including the determined at least two combustion reaction parameters in an Arrhenius equation; and predicting a time of combustion (CA50) for the combustion cycle using the Arrhenius equation, the time of combustion (CA50) corresponding to a crank angle (CA) at which a mass fraction of the fuel burned is 50%. Procedure according to Claim 9 , wherein an exponent of each of the determined at least two combustion reaction parameters is a predetermined number (B or C or D). A method for predicting a timing of combustion of a mixture inside a cylinder (21) for a cycle of an HCCI internal combustion engine (2), comprising: determining at least two combustion _{reaction parameters} from combustion _{reaction parameters} which is a pressure state _variable (P _{cyl_10BTDC} ) which is based on a cylinder pressure inside the cylinder (21) is determined, a fuel mass fraction (φ, φ ^-1 ) determined based on the state of the fuel mass and the air mass inside the cylinder (21), and a variable regarding the state of the burned gas ( X _rg ), which is determined based on the retention of the burned gas inside the cylinder (21); Determining at least one fuel condition parameter from fuel condition parameters that include a mixed prediction variable (Ne, Ne ^-1 ) for predicting the mixed condition of the fuel inside the cylinder (21), an injection completion timing (Eol) at which the fuel injection is completed, and a heat loss prediction variable ( T _ex - T _in ) for predicting heat loss due to heat transfer between a wall surface and the fuel inside the cylinder (21); Plotting the determined combustion reaction and fuel condition parameters in an Arrhenius equation; and predicting a time of combustion (CA50) for the combustion cycle using the Arrhenius equation, the time of combustion (CA50) corresponding to a crank angle (CA) at which a mass fraction of the fuel burned is 50%. Procedure according to Claim 11 , wherein an exponent of each of the determined combustion reaction and fuel condition parameters is a predetermined number (B or C or D, F or G or H).

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