WO2020195223A1

WO2020195223A1 - Internal combustion engine control device

Info

Publication number: WO2020195223A1
Application number: PCT/JP2020/004728
Authority: WO
Inventors: 隆太郎小祝; 一浩押領司; 佐藤　真也
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2019-03-27
Filing date: 2020-02-07
Publication date: 2020-10-01
Also published as: JP7356245B2; JP2020159298A

Abstract

Provided is an internal combustion engine control device with which the state of an air-fuel mixture in a cylinder can be estimated accurately. This internal combustion engine control device 10 is provided with control units 101 and 110 for acquiring an ignition timing at which a spark plug ignites an air-fuel mixture inside a cylinder and a fuel injection start timing at which an injector begins injecting fuel into the cylinder. The control units 101 and 110 calculate a degree of variation in the distribution of the air-fuel mixture in the cylinder on the basis of the ignition timing and the fuel injection start timing.

Description

Internal combustion engine controller

The present invention relates to an internal combustion engine control device.

In an internal combustion engine, particulate matter (PM: Particulate Matter) is generated when the air-fuel mixture, which is a mixture of fuel and air, burns. In particular, in an engine that injects fuel directly into the fuel chamber of a cylinder, a so-called direct injection engine, there is an air-fuel mixture (hereinafter, referred to as a rich air-fuel mixture) in which the proportion of fuel is locally concentrated. Therefore, in the fuel chamber of the direct injection engine, the ratio of fuel in the air to the air-fuel mixture tends to be uneven, and the PM emission amount increases.

Therefore, a PM collection filter is provided in order to reduce PM contained in the exhaust gas of the internal combustion engine. The PM collection filter needs to burn and remove the collected PM in order to prevent clogging. At this time, if PM is excessively deposited on the PM collection filter, the temperature of the PM collection filter may rise excessively due to the combustion of PM, and the filter may be damaged. Therefore, it is necessary to accurately grasp the amount of PM accumulated in the PM collection filter, and it is important to estimate the amount of PM flowing into the PM collection filter.

In addition, the amount of PM produced increases at the location where the rich mixture and fuel adhere in a specific temperature range. Therefore, in order to estimate the amount of PM, it is important to estimate the state of the air-fuel mixture in the cylinder and the ratio of the fuel adhering to the wall surface in the cylinder. As a technique for estimating the state of the air-fuel mixture, for example, there is a technique described in Patent Document 1.

Patent Document 1 describes a technique including an injection fuel classification means and an air-fuel mixture state estimation means. The injection fuel classification means classifies the fuel that is continuously injected in the cylinder of the internal combustion engine for a predetermined injection period from the start of the predetermined injection into a plurality of parts. Then, the air-fuel mixture state estimation means assumes that each part of the classified injection fuel is independently and sequentially injected according to the lapse of time from a predetermined injection start time, and each part of the injection fuel is a cylinder. The state of each air-fuel mixture formed by mixing with the in-cylinder gas sucked into the inside is individually estimated.

The technique described in Patent Document 1 is a technique for estimating the state of an air-fuel mixture in a diesel engine as an internal combustion engine. The diesel engine is diffusion combustion in which the fuel injected from the fuel injection device evaporates and combustion proceeds while taking in air. In diffusion combustion, the movement of the fuel spray and the combustion reaction proceed at the same time, so that the fuel spray dominates the combustion.

Japanese Unexamined Patent Publication No. 2006-274991

However, in a gasoline engine, a mixture of fuel and air is activated by the ignition energy generated by the spark plug, starts combustion, and the performance starts in a combustion form called flame propagation in the premixed combustion that progresses in the cylinder. is there. Premixed combustion differs from diesel engine combustion because the air-fuel mixture and ignition timing dominate the combustion. And the gasoline engine usually injects fuel during the intake stroke.

Therefore, when the technique described in Patent Document 1 is applied, the calculation period per cycle becomes longer, and the area for dividing the fuel increases. As a result, in the technique described in Patent Document 1, the calculation load increases, and it is difficult to accurately estimate the mixed state of fuel and air in the cylinder, that is, the state of the air-fuel mixture.

The purpose of this object is to provide an internal combustion engine control device capable of accurately estimating the state of the air-fuel mixture in the cylinder of the cylinder in consideration of the above problems.

In order to solve the above problems and achieve the object, the internal combustion engine control device is an internal combustion engine control device that controls an internal combustion engine. The internal combustion engine consists of a cylinder, a piston that slides inside the cylinder, a crankshaft that is connected to the piston, an injector that injects fuel into the cylinder, and a mixture of air and fuel inside the cylinder. It has a spark plug that ignites the engine.
The internal combustion engine control device includes a control unit that acquires the ignition timing at which the spark plug ignites the air-fuel mixture in the cylinder and the fuel injection start timing at which the injector starts the injection of fuel into the cylinder. The control unit calculates the degree of dispersion of the air-fuel mixture distribution in the cylinder based on the ignition timing and the fuel injection start timing.

Further, in order to solve the above problems and achieve the object, the internal combustion engine control device is an internal combustion engine control device that controls an internal combustion engine. The internal combustion engine consists of a cylinder, a piston that slides inside the cylinder, a crankshaft that is connected to the piston, an injector that injects fuel into the cylinder, and a mixture of air and fuel inside the cylinder. It has a spark plug that ignites the engine.
The internal combustion engine control device includes a control unit that acquires the opening / closing timing of an exhaust valve arranged so as to open / close the exhaust port of the cylinder, and the intake pressure which is the pressure of the air taken into the cylinder. The control unit calculates the fuel adhesion ratio, which is the ratio of the amount of fuel adhering to the wall surface of the cylinder and the crown surface of the piston, based on the opening / closing timing of the exhaust valve and the intake pressure.

According to the internal combustion engine control device having the above configuration, the state of the air-fuel mixture in the cylinder of the cylinder can be accurately estimated.

It is a schematic block diagram which shows the system structure of the internal combustion engine equipped with the internal combustion engine control device which concerns on embodiment. It is a block diagram which shows the structure of the internal combustion engine control device which concerns on Example of Embodiment. It is a block diagram which shows the structure of the GPF control part in the internal combustion engine control device which concerns on embodiment. It is a characteristic figure which shows the generation rate of PM. It shows the ratio of the air-fuel mixture in the cylinder of the internal combustion engine, and is a graph which shows the relationship between the ratio of the air-fuel mixture and the equivalent ratio. It is a graph which shows the beta function which is a probability density function. It is a flowchart which shows the calculation operation of the degree of dispersion degree of the air-fuel mixture distribution in the internal combustion engine control device which concerns on embodiment. It is explanatory drawing which shows the shape of the spray in the central cross section of the fuel spray injected from an injector. It is explanatory drawing which shows the vaporization rate of fuel after fuel injection. It is a graph which shows the mixing fraction in a cylinder immediately after a fuel injection and at an ignition timing. It is a figure which shows the adhesion state of fuel in a cylinder. It is a flowchart which shows the calculation operation of the fuel adhesion ratio in the internal combustion engine control device which concerns on Example of Embodiment. It is a figure which shows the position of a piston and the state of fuel adhesion. It is a flowchart which shows the calculation operation of the temperature and pressure history in the internal combustion engine control device which concerns on Example of Embodiment. It is a graph which shows the relationship between a mixture ratio and a fuel concentration. It shows the reaction rate map caused by the air-fuel mixture, and is a characteristic diagram showing the reaction rate caused by the air-fuel mixture on the map represented by the reaction gas temperature of the air-fuel mixture and the distribution constant. It shows the reaction rate map due to fuel adhesion, and is a characteristic diagram showing the relationship between the reaction gas temperature of the air-fuel mixture and the reaction rate due to fuel adhesion. It is a flowchart which shows the calculation operation of the PM emission amount in the internal combustion engine control device which concerns on Example of Embodiment. It is a schematic diagram which shows the internal state of GPF and PM flowing into GPF. It is a flowchart which shows the calculation operation of the PM accumulation amount in the internal combustion engine control device which concerns on Example of Embodiment. It shows a PM combustion rate map, and is a characteristic figure which shows the relationship between the upstream temperature of GPF and PM combustion rate. It shows the PM combustion rate correction coefficient map, and is the characteristic figure which shows the relationship between the air excess rate and PM combustion rate correction coefficient. It is a flowchart which shows the determination operation of the regeneration control command in the internal combustion engine control device which concerns on Example of Embodiment.

1. 1. Example of Embodiment Hereinafter, the internal combustion engine control device according to the embodiment (hereinafter, referred to as “this example”) will be described with reference to FIGS. 1 to 23. The common members in the drawings are designated by the same reference numerals.

1-1. Configuration example of an internal combustion engine First, a configuration example of an internal combustion engine will be described.
FIG. 1 is a schematic configuration diagram showing a system configuration of the internal combustion engine of this example.

The internal combustion engine 2 shown in FIG. 1 is an in-cylinder injection type internal combustion engine (direct injection engine) that directly injects fuel made of gasoline into the cylinder. The internal combustion engine 2 is a four-cycle engine that repeats four strokes of an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. Further, the internal combustion engine 2 is, for example, a multi-cylinder engine including four cylinders (cylinders). The number of cylinders of the internal combustion engine 2 is not limited to four, and may have six or eight or more cylinders. Further, the number of cycles of the internal combustion engine 2 is not limited to 4 cycles.

As shown in FIG. 1, the internal combustion engine 2 includes a cylinder 21, a piston 22, a crankshaft 23, an intake valve 24, an exhaust valve 25, a spark plug 26, and an injector 27 which is a fuel injection device. are doing. The internal combustion engine 2 is controlled by the internal combustion engine control device 10.

The piston 22 is slidably arranged in the cylinder 21a of the cylinder 21. The piston 22 compresses the fuel-gas mixture that has flowed into the cylinder 21a of the cylinder 21. Then, the piston 22 reciprocates in the cylinder 21a due to the combustion pressure generated in the cylinder 21a.

A crankshaft 23 is connected to the piston 22 via a connecting rod. Then, the reciprocating motion of the piston 22 is converted into a rotary motion by the crankshaft 23. Further, the crankshaft 23 is provided with a crank angle sensor 29 that detects the crank angle of the crankshaft 23. The crank angle sensor 29 detects the crank angle of the crankshaft 23 from the rotating disk provided on the crankshaft 23. The crank angle sensor 29 is connected to an internal combustion engine control device 10 described later. Then, the crank angle sensor 29 outputs the detected angle information regarding the crank angle to the internal combustion engine control device 10.

The intake valve 24 is arranged to be openable and closable at the intake port of the cylinder 21, and the exhaust valve 25 is arranged to be openable and closable at the exhaust port of the cylinder 21. The intake valve 24 is in contact with an intake side camshaft (not shown), and the exhaust valve 25 is in contact with an exhaust side camshaft (not shown). Then, the intake valve 24 and the exhaust valve 25 are driven by the rotation of the intake side camshaft and the exhaust side camshaft. When the intake valve 24 is driven, gas (air) flows into the cylinder 21a of the cylinder 21 from the intake port. Further, by driving the exhaust valve 25, the exhaust gas after combustion is discharged from the exhaust port of the cylinder 21.

The injector 27 injects fuel into the cylinder 21a of the cylinder 21. The injector 27 is connected to the internal combustion engine control device 10. The internal combustion engine control device 10 calculates the target fuel injection amount by dividing the intake amount output from the airflow sensor 42, which will be described later, by the target air-fuel ratio determined by the rotation speed, the intake pressure, and the like. Then, the internal combustion engine control device 10 injects fuel from the injector 27 according to the calculated target fuel injection amount. As a result, in the cylinder 21a, an air-fuel mixture in which air and fuel are mixed is generated.

A spark plug 26 and an injector 27 are attached to the cylinder 21. An ignition coil (not shown) is connected to the spark plug 26. The ignition coil generates a high voltage under the control of the internal combustion engine control device 10 and applies it to the spark plug 26. As a result, sparks are generated in the spark plug 26. Then, the spark generated in the spark plug 26 burns the air-fuel mixture in the cylinder 21a and explodes. The piston 22 is pushed down by the exploding air-fuel mixture. The pushing-down motion of the piston 22 is converted into a rotational motion of the crankshaft 23, which becomes a driving force for a vehicle or the like.

Further, the cylinder 21 is provided with a cooling water sensor 28 that measures the temperature of the cooling water that cools the cylinder 21. The cooling water sensor 28 is connected to the internal combustion engine control device 10, and outputs the measured temperature of the cooling water to the internal combustion engine control device 10.

An intake pipe 31 for taking in gas composed of air is connected to the intake port of the cylinder 21, and an exhaust pipe 32 for exhausting the exhaust gas is connected to the exhaust port of the cylinder 21. Further, the intake pipe 31 and the exhaust pipe 32 are connected by an EGR pipe 33.

The EGR pipe 33 returns a part of the exhaust gas passing through the exhaust pipe 32 to the intake pipe 31. This reduces pumping loss. The EGR tube 33 is provided with an EGR valve 45. The EGR valve 45 regulates the flow rate of gas passing through the EGR pipe 33.

The intake pipe 31 is provided with a throttle valve 41 and an air flow sensor 42. The throttle valve 41 is provided on the upstream side of the intake pipe 31 at the connection point with the intake port and the EGR pipe 33. The throttle valve 41 is driven so as to be openable and closable by a drive motor (not shown). Then, the opening degree of the throttle valve 41 is adjusted based on the accelerator operation of the driver.
As a result, the amount of gas taken into the intake pipe 31 (intake amount) is adjusted.

The air flow sensor 42 measures the amount of intake air taken into the intake pipe 31. The air flow sensor 42 is connected to the internal combustion engine control device 10. The air flow sensor 42 outputs the measured intake air amount to the internal combustion engine control device 10.

Further, the intake pipe 31 is provided with an intake pressure sensor 43 and an intake temperature sensor 44. The intake pressure sensor 43 and the intake temperature sensor 44 are connected to the internal combustion engine control device 10. The intake pressure sensor 43 measures the pressure (intake pressure) of the gas passing through the intake pipe 31. Then, the intake pressure sensor 43 outputs the measured intake pressure to the internal combustion engine control device 10. Further, the intake air temperature sensor 44 measures the temperature of the gas passing through the intake pipe 31 (intake air temperature). Then, the intake air temperature sensor 44 outputs the measured intake air temperature to the internal combustion engine control device 10.

The exhaust pipe 32 is provided with an air-fuel ratio sensor 46, a three-way catalyst 34, and a gasoline particulate filter (hereinafter referred to as “GPF”) 35.
The air-fuel ratio sensor 46 measures the oxygen concentration contained in the exhaust gas passing through the exhaust pipe 32. Then, the air-fuel ratio sensor 46 is connected to the internal combustion engine control device 10, and outputs the measured oxygen concentration to the internal combustion engine control device 10.

The three-way catalyst 34 is provided in the intermediate portion of the exhaust pipe 32. The three-way catalyst 34 purifies harmful substances contained in the exhaust gas by an oxidation / reduction reaction.

A GPF 35 is provided on the downstream side of the three-way catalyst 34 in the exhaust pipe 32. The GPF35, which is a PM collection filter, collects particulate matter contained in the exhaust gas, so-called PM. Further, a GPF upstream temperature sensor 47 is provided on the upstream side of the GPF 35, that is, between the three-way catalyst 34 and the GPF 35. The GPF upstream temperature sensor 47 measures the temperature of the exhaust gas flowing into the GPF 35. Then, the GPF upstream temperature sensor 47 is connected to the internal combustion engine control device 10, and outputs the measured exhaust gas temperature to the internal combustion engine control device 10.

Further, the GPF 35 is provided with a differential pressure sensor 48. The differential pressure sensor 48 measures the pressure difference (differential pressure) between the upstream side and the downstream side of the GPF 35. Then, the differential pressure sensor 48 is connected to the internal combustion engine control device 10, and outputs the measured differential pressure to the internal combustion engine control device 10.

In this example, an example in which the three-way catalyst 34 and the GPF 35 are configured as separate members has been described, but the present invention is not limited to this. For example, it may be a PM collection filter such as a quaternary catalyst in which a GPF 35 is provided with a purification function of a three-way catalyst 34.

1-2. Configuration Example of Internal Combustion Engine Control Device 10 Next, a configuration example of the internal combustion engine control device 10 will be described with reference to FIG.
FIG. 2 is a block diagram showing the configuration of the internal combustion engine control device 10.

As shown in FIG. 2, the internal combustion engine control device 10 which is an ECU (Engine Control Unit) includes a CPU (Central Processing Unit) 101 showing an example of a control unit, a RAM (Random Access Memory) 102, and a ROM (Read Only). It has a Memory) 103, an input / output port 104, and an input circuit 105. Further, the internal combustion engine control device 10 has a GPF control unit 110 showing an example of the control unit.

The input circuit 105, which shows an example of the receiving unit, inputs the output of each sensor such as the intake amount from the airflow sensor 42, the intake pressure from the intake pressure sensor 43, the intake temperature from the intake temperature sensor 44, and the rotation speed from the crank angle sensor 29. Will be done. The input signal input to the input circuit 105 is not limited to the above. The input circuit 105 performs signal processing such as noise removal on the input signal and sends it to the input / output port 104. The value input to the input port of the input / output port 104 is stored in the RAM 102.

The ROM 103, which shows an example of the storage unit, stores a control program that describes the contents of various arithmetic processes executed by the CPU 101, a MAP, a data table, and the like used for each process. The RAM 102 is provided with a storage area for storing the value input to the input port of the input / output port 104 and the value representing the operation amount of each actuator calculated according to the control program. Further, a value representing the operation amount of each actuator stored in the RAM 102 is sent to the output port of the input / output port 104.

Further, each drive circuit for driving the injector 27, the spark plug 26, and the throttle valve 41 is connected to the input / output port 104. Then, the drive signal set in the output port of the input / output port 104 is sent to the injector 27, the spark plug 26, and the throttle valve 41 via each drive circuit.

Further, the GPF control unit 110 is connected to the input / output port 104. The GPF control unit 110 calculates the internal temperature of the GPF 35 (hereinafter referred to as the GPF temperature) and the amount of PM deposited on the GPF 35 based on the information output from various sensors. Then, when the calculated GPF temperature and PM accumulation amount exceed the set threshold values, the PM in the GPF 35 is burned and removed by controlling the spark plug 26 and the injector 27 and adjusting the air-fuel ratio and the ignition timing.
In this example, this operation of burning and removing PM in GPF is referred to as regeneration control of GPF35.

1-3. Configuration Example of GPF Control Unit 110 Next, a configuration example of the GPF control unit 110 will be described with reference to FIG.
FIG. 3 is a block diagram showing the configuration of the GPF control unit 110.

As shown in FIG. 3, the GPF control unit 110 includes a scattering degree calculation processing unit 201, a fuel adhesion ratio calculation processing unit 202, a temperature / pressure state calculation processing unit 203, a PM emission amount calculation processing unit 204, and PM deposition. It has an amount calculation processing unit 205 and a reproduction control processing unit 206. The PM emission amount calculation processing unit 204 is connected to the scattering degree calculation processing unit 201, the fuel adhesion ratio calculation processing unit 202, and the temperature / pressure state calculation processing unit 203. Then, the PM discharge amount calculation processing unit 204 is connected to the PM accumulation amount calculation processing unit 205, and the PM accumulation amount calculation processing unit 205 is connected to the regeneration control processing unit 206.

The dispersion degree calculation processing unit 201 is based on the engine speed, fuel injection pulse, fuel injection start timing, ignition timing, etc., and the degree of dispersion of the air-fuel mixture distribution in the cylinder 21a of the cylinder 21, that is, the air-fuel mixture in the cylinder 21a. Calculate the state of. Then, the dispersion degree calculation processing unit 201 outputs the calculated dispersion degree of the air-fuel mixture distribution to the PM emission amount calculation processing unit 204. The method of calculating the degree of dispersion of the air-fuel mixture distribution in the dispersion degree calculation processing unit 201 will be described later.

The fuel adhesion ratio calculation processing unit 202 is based on the engine speed, fuel injection pulse, fuel injection start timing, ignition timing, cooling water temperature, intake pressure, fuel pressure, exhaust valve opening / closing timing, intake pressure, and the like. Calculate the injection amount of the fuel injected into. Further, based on the above information, the fuel adhesion ratio calculation processing unit 202 determines the ratio (fuel adhesion) of the fuel N2 attached to the wall surface of the cylinder 21a and the fuel N3 (see FIG. 11) attached to the crown surface 22a of the piston 22. Percentage) is calculated. Then, the fuel adhesion ratio calculation processing unit 202 outputs the calculated fuel adhesion ratio to the PM emission amount calculation processing unit 204. The method of calculating the fuel adhesion ratio in the fuel adhesion ratio calculation processing unit 202 will be described later.

The temperature / pressure state calculation processing unit 203 calculates the temperature history of the air-fuel mixture in the cylinder 21a and the pressure history of the cylinder 21a based on the intake pressure, the intake temperature, and the cylinder volume of the cylinder 21. The temperature / pressure state calculation processing unit 203 outputs the calculated temperature / pressure history to the PM emission amount calculation processing unit 204. The method of calculating the temperature / pressure history in the temperature / pressure state calculation processing unit 203 will be described later.

The PM emission calculation processing unit 204 calculates the PM emission (PM emission) emitted from the internal combustion engine 2 based on the degree of dispersion of the air-fuel mixture distribution, the fuel adhesion ratio, and the temperature and pressure history. Then, the PM discharge amount calculation processing unit 204 outputs the calculated PM discharge amount to the PM accumulation amount calculation processing unit 205. The method of calculating the PM emission amount in the PM emission amount calculation processing unit 204 will be described later.

The PM accumulation amount calculation processing unit 205 calculates the amount of PM accumulated in the GPF35 (PM accumulation amount) based on the PM discharge amount. Then, the PM accumulation amount calculation processing unit 205 outputs the calculated PM accumulation amount to the regeneration control processing unit 206. The method of calculating the PM deposit amount in the PM deposit amount calculation processing unit 205 will be described later.

The regeneration control processing unit 206 determines whether or not to perform regeneration control of the GPF 35 based on the amount of PM deposited. Then, the reproduction control processing unit 206 commands the reproduction control based on the determination result. The drive circuit (not shown) generates a drive signal based on the regeneration control command from the regeneration control processing unit 206 to drive the spark plug 26 and the injector 27. The determination operation in the reproduction control processing unit 206 will be described later.

The GPF control unit 110 described above may be provided in the CPU 101. Therefore, various calculation processing units included in the GPF control unit 110 are provided in the CPU 101. Then, the CPU 101 calculates the degree of dispersion of the air-fuel mixture, the fuel adhesion ratio, the temperature and pressure history of the air-fuel mixture, the PM discharge amount, and the PM accumulation amount, and determines the regeneration control of the GPF 35.

Further, as shown in FIG. 2, the GPF control unit 110 may be provided in the internal combustion engine control device 10 as a control unit separate from the CPU 101.

2. 2. Characteristics of PM generation Next, the characteristics of PM generation will be described with reference to FIG.
FIG. 4 is a characteristic diagram showing the PM generation rate, and FIG. 5 is a graph showing the air-fuel mixture distribution in the cylinder 21a and showing the relationship between the air-fuel mixture ratio and the equivalent ratio.

In FIG. 4, the horizontal axis shows the temperature of the reaction gas, that is, the air-fuel mixture, and the vertical axis shows the equivalent ratio. The equivalent ratio is an index showing the fuel concentration in the air-fuel mixture, and is the value obtained by dividing the theoretical air-fuel ratio, which is the theoretically highest combustion efficiency air-fuel ratio, by the actual air-fuel ratio. As shown in FIG. 4, the rate of PM production increases, with no increase in the equivalent ratio. As described above, in order to estimate the amount of PM with high accuracy, it is important to estimate how much an air-fuel mixture having a large equivalent ratio in the cylinder 21a exists.

In the example shown in FIG. 4, an example in which the equivalent ratio is used as the vertical axis has been described, but the present invention is not limited to this, and the air-fuel ratio and the fuel-air ratio are used as indexes related to the fuel-air ratio. Fuel mass fraction and the like may be applied.

Next, the distribution of the air-fuel mixture in the cylinder 21a in the highly homogeneous state and the low-homogeneous state of the air-fuel mixture will be described.
FIG. 5 is a diagram showing the air-fuel mixture distribution in the cylinder 21a. In FIG. 5, the horizontal axis shows the equivalent ratio and the vertical axis shows the air-fuel mixture ratio.

Gasoline engines usually burn in a state where fuel and air are uniformly mixed (highly homogeneous state). However, in the in-cylinder injection type internal combustion engine 2 that injects fuel directly into the in-cylinder 21a as shown in FIG. 1, the fuel injection start timing such as fuel injection in the compression stroke is late, or the air flow is slow. If it is weak, the mixture of fuel and air will be insufficient. Therefore, the in-cylinder 21a tends to be in a state (low homogeneous state) in which an air-fuel mixture (hereinafter, rich air-fuel mixture) in which the ratio of fuel is locally concentrated is present. Further, as shown in FIG. 5, when the equivalent ratio is higher than a certain value (rich), that is, when the ratio of fuel becomes high, the amount of PM produced increases.

Therefore, PM generation can be estimated by estimating the air-fuel mixture distribution in the cylinder 21a. As one means of estimating this air-fuel mixture distribution, there is a method of estimating the air-fuel mixture distribution using the probability density function of the mixed fraction space.

3. 3. Calculation method using the probability density function Next, a method of calculating the air-fuel mixture distribution in the cylinder 21a using the probability density function of the mixed fraction space (graph with the mixed fraction on the horizontal axis) will be described. In this example, a method of estimating the air-fuel mixture distribution in the cylinder 21a using the probability density function will be described, but the method of estimating the air-fuel mixture distribution is not limited to this.

Beta function is one of the probability density functions. The beta function P (Z) in the mixed fraction space is obtained by the following equations 1 to 4.
[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

In Equations 1 to 4 described above, Z is the mixed fraction [-], Z _ave is the in-cylinder average value of the mixed fraction, σ is the variance of the mixed fraction, A / F is the air-fuel ratio, and a and b are the distribution constants. Is shown.

FIG. 6 is a diagram showing the distribution of beta functions.
As shown in FIG. 6, the beta function P (Z) becomes convex upward, convex downward, or mixed fraction Z depending on the combination of the in-cylinder average value Z _ave of the mixed fraction and the variance σ of the mixed fraction. On the other hand, a distribution such as monotonous decrease can be obtained. For example, a state in which fuel and air are mixed well (high homogeneous state), the _{_{σ = a 1, Z ave =}} b 1, beta function P (Z) becomes convex upward. The state in which fuel and air are separated in cylinder 21a (low homogeneous _{_{state), σ = a 2, Z ave}} = In _{b 2,} beta function P (Z) becomes convex downward. Here, the in-cylinder average value Z _ave of the mixed fraction can be given from the average air-fuel ratio A / F of the in-cylinder 21a. In this example, an example in which the average air-fuel ratio A / F is set to 14.7 as the ideal air-fuel ratio has been described, but the present invention is not limited to this.

Here, the important parameter when estimating the state of the air-fuel mixture in the probability density function is the variance σ. If the change in dispersion can be calculated based on the operating conditions of the vehicle and the amount of operation of each actuator such as the injector 27 and the spark plug 26, the state of the air-fuel mixture distribution in the cylinder 21a can be calculated by the probability density function. ..

4. Calculation operation of the degree of dispersion of the air-fuel mixture distribution Next, the operation of calculating the degree of dispersion of the air-fuel mixture distribution in the dispersion degree calculation processing unit 201 will be described with reference to FIG. 7.
FIG. 7 is a flowchart showing the calculation operation of the scattering degree of the air-fuel mixture distribution in the scattering degree calculation processing unit 201.

As shown in FIG. 7, first, the dispersion degree calculation processing unit 201 acquires the operating conditions of the internal combustion engine 2 (step S11). In the process of step S11, the dispersion degree calculation processing unit 201 acquires output information of various sensors, an operation amount of each actuator, and the like as operating conditions of the internal combustion engine 2. The output information and the amount of operation of the sensor include, for example, the rotation speed Ne, the fuel injection pulse ti, the fuel injection start timing θ _SOI , the ignition timing θ _{ADV, and the} like.

The rotation speed Ne is the rotation speed of the crankshaft 23, and the fuel injection pulse ti is a period during which fuel is injected from the injector 27. Further, the fuel injection start time θ _SOI is a time when fuel injection is started from the injector 27 with respect to the crank angle. The ignition timing θ _ADV is the timing at which the spark plug 26 ignites the air-fuel mixture in the cylinder 21a with respect to the crank angle. The rotation speed Ne is acquired based on the detection information of the crank angle sensor 29. The fuel injection pulse ti and the fuel injection start time θ _SOI are known as the control amount of the injector 27, and the ignition timing θ _ADV is known as the control amount of the spark plug 26.

Next, the scattering degree calculation processing unit 201 calculates the rotation period ct based on the acquired rotation speed Ne (step S12). The rotation cycle tc [s] is calculated by the following equation 5 using the rotation speed Ne [rpm].
[Equation 5]

Next, after calculating the rotation cycle tc, the scatter degree calculation processing unit 201 calculates the fuel injection end time θ _EOI [ATDC] (step S13). The fuel injection end time θ _EOI is calculated by the following equation 6 using the fuel injection pulse ti [s], the fuel injection start time θ _SOI [ATDC], and the rotation speed Ne [rpm].
[Equation 6]

After calculating the fuel injection end time θ _EOI , the scatter degree calculation processing unit 201 calculates the mixing time tm (step S14). Here, the mixing time tm represents the time from the end of fuel injection to ignition. The mixing time tm [s] is calculated by the following equation 7 using the ignition timing θ _ADV [ATDC], the rotation speed Ne [rpm], and the fuel injection end time θ _EOI [ATDC].
[Equation 7]

After calculating the mixing time tm, the dispersion degree calculation processing unit 201 calculates the dispersion degree of the air-fuel mixture distribution, that is, the variance σ (step S15). The degree of dispersion σ of the air-fuel mixture distribution is calculated by the following equation 8 using the mixing time tm [s].
[Equation 8]

Further, the degree of dispersion σ of the air-fuel mixture distribution can be calculated more accurately from the following equation 9 by using the injection pulse ti [s], the rotation period ct [s], and the mixing time tm [s].
[Equation 9]

As a result, the calculation operation of the dispersion degree σ of the air-fuel mixture distribution in the dispersion degree calculation processing unit 201 is completed.

4-1. Basis for calculating the degree of dispersion of the air-fuel mixture distribution Next, the basis for calculating the degree of dispersion σ of the air-fuel mixture distribution using the injection pulse ti [s], the rotation period ct [s], and the mixing time tm [s] is shown in the figure. This will be described with reference to FIGS. 8 to 10.
Here, the air-fuel mixture composed of fuel and air is formed through three processes of "formation of fuel spray", "evaporation of the formed spray", and "mixing of evaporated fuel and air".

[Formation of fuel spray]
First, the relationship between "formation of fuel spray" and the fuel injection pulse ti [s] will be described with reference to FIG.
FIG. 8 is an explanatory view showing the shape of the spray in the central cross section of the fuel spray injected from the injector 27.

As shown in FIG. 8, the fuel injected from the injector 27 is sprayed in a substantially conical shape. Therefore, the central cross section of the fuel spray is triangular. Here, the spray tip speed _{u tip} is calculated by the following equation 10.
[Equation 10]

U ₀ shown in the formula 10 is the initial velocity [m / s] of the injection, and t is the injection time [s].

Further, the area S1 of the spray center cross section which becomes a triangle at the end of injection by the integration of the equation 10 is calculated by the following equation 11.
[Equation 11]

Θ in Equation 11 is the injection angle [rad], and ti is the fuel injection pulse [s].

As shown in Equation 11, the initial position of the spray at the end of injection can be calculated by a function of the initial injection speed u ₀ , the injection time t, and the injection angle θ. Here, the initial injection speed u ₀ , the injection angle When θ is constant, the initial position of the spray at the end of injection is a function of the fuel injection pulse ti. Therefore, by using the fuel injection pulse ti, that is, the period during which the fuel is injected, the degree of dispersion σ of the air-fuel mixture distribution in the cylinder 21a can be estimated in consideration of the initial distribution of the fuel. As a result, the calculation accuracy of the degree of dispersion σ of the air-fuel mixture distribution can be improved by the fuel injection pulse ti.

[Evaporation of the formed spray]
Next, the relationship between the "evaporation of the formed spray" and the rotation cycle tc [s] will be described with reference to FIG.
FIG. 9 is an explanatory diagram showing the vaporization rate of fuel after fuel injection. The SOI in FIG. 9 indicates the start time of fuel injection, and the EOI indicates the end time of fuel injection.

As shown in FIG. 9, the vaporization rate of the fuel increases from 0 when the injection is completed and the EOI is completed. Then, the time from the end time EOI of the fuel injection until the vaporization rate becomes 1 is the delay time until the start of mixing, that is, the time that occurs until the fuel evaporates (evaporation delay time). Here, a model formula in which the evaporation rate is regulated by the ratio of the saturated vapor pressure of the fuel to the pressure is shown in the following formula 12.
[Equation 12]

Further, the following equation 13 shows a model equation in which the temperature change during the intake stroke is controlled by the heat transfer of the wall surface of the cylinder 21a.
[Equation 13]

Here, ρ _f is the gas density of the fuel component [kg / m ³ ], ρ _l is the liquid density of the fuel component [kg / m ³ ], D is the nucleic acid coefficient [m ² / s ² ], and d is the particle size [m ² / s ² ]. m], ρ _{s, f} are saturated gas pressure [Pa], M is the mass [kg] of the cylinder 21a, C _p is the constant pressure specific heat [J / Kg / K], and α is the heat transfer rate [W / m ² / K] and S are the surface area [m ² ] of the cylinder 21a, T is the gas temperature [K], and T _w is the wall surface temperature [K].

Then, the following equation 14 can be derived from the equations 12 and 13.
[Equation 14]

Equation 14 shows that the evaporation delay time shown in FIG. 9 is a function of the rotation cycle tc. As a result, the evaporation delay time can be obtained by using the rotation cycle tk. As a result, by using the rotation cycle tk, the degree of dispersion σ of the air-fuel mixture distribution in the cylinder 21a can be estimated in consideration of the evaporation delay time of the formed spray. Therefore, the calculation accuracy of the degree of dispersion σ of the air-fuel mixture distribution can be improved by the rotation period tc.

[Mixing of evaporated fuel and air]
Next, the relationship between "mixing of evaporated fuel and air" and the mixing time tm [s] will be described with reference to FIG.
FIG. 10 shows the mixing fraction of the cylinder 21a immediately after fuel injection and at the ignition timing. The solid line shown in FIG. 10 shows the mixing fraction immediately after fuel injection, and the dotted line shows the mixing fraction at the ignition timing.

As shown in FIG. 10, the dispersion of the mixed fraction immediately after the fuel injection is large, but the mixing of the fuel and the air progresses due to the turbulent diffusion, and the in-cylinder average value Z _ave approaches. Then, at the ignition timing, the dispersion becomes small. The diffusion of fuel air can be examined from the one-dimensional diffusion equation, which is the basic equation of the diffusion phenomenon. The one-dimensional diffusion equation is shown in Equation 15 below.
[Equation 15]

The exact solution of Equation 15 can be obtained by imposing the boundary condition that Z = 0 at infinity. The exact solution is given by Equation 16 below.
[Equation 16]

Further, in the equation 16, the variance σ is represented by the following equation 17 [Equation 17].

Here, when mixing by turbulent diffusion is targeted, D is evaluated by the turbulent diffusion coefficient. The turbulent diffusion coefficient D can be expressed by the following equation 18 using the turbulent energy k and the turbulent energy dissipation rate ε.
[Equation 18]

Re is a Reynolds number.

For the sake of simplicity, assuming that the mixing of fuel air proceeds in the time from the end of injection to the ignition timing, the time t in Equation 17 is given by the time from the end of injection to the ignition timing, that is, the mixing time tm. As a result, the variance σ of the air-fuel mixture distribution in the real space is obtained by the following equation 19.
[Equation 19]

In this way, by using the mixing time tm, it is possible to estimate the degree of dispersion σ of the air-fuel mixture distribution in the cylinder 21a in consideration of the turbulent diffusion process of fuel and air. As a result, the calculation accuracy of the degree of dispersion σ of the air-fuel mixture distribution can be improved by the mixing time tm.

5. Calculation operation of fuel adhesion ratio and PM generation characteristics Next, FIGS. 11 to 13 show the calculation operation of the fuel adhesion ratio and the PM generation characteristics in the fuel adhesion ratio calculation processing unit 202.
First, the relationship between the fuel adhesion ratio and PM generation will be described with reference to FIG.
FIG. 11 is a diagram showing a state of adhesion of fuel in the cylinder 21a.

In the in-cylinder injection type internal combustion engine 2, it becomes difficult to promote atomization of fuel in the in-cylinder 21a of the cylinder 21 especially when the engine is cold. Therefore, as shown in FIG. 11, when the fuel N1 is injected from the injector 27 into the cylinder 21a, the fuels N2 and N3 adhere to the wall surface of the cylinder 21a and the crown surface 22a of the piston 22. Therefore, when the engine is cold, the fuel injection start time is usually set during the intake stroke, and so-called intake stroke injection is performed. Then, the engine from fuel injection to ignition is secured as long as possible to promote atomization of the injected fuel.

However, it is difficult to eliminate all the fuels N2 and N3 adhering to the wall surface of the cylinder 21a and the crown surface 22a of the piston 22 even if the intake stroke injection is performed. Then, some of the attached fuels N2 and N3 are not used for combustion and remain attached to the wall surface of the cylinder 21a and the crown surface 22a of the piston 22 even after the combustion of the engine. The remaining fuel is gradually atomized during subsequent engine combustion, is incompletely burned, and is discharged from the cylinder 21. Incomplete combustion of the fuel and its discharge caused the generation of PM. As described above, it is important to estimate the fuel adhesion ratio when the engine is cold when estimating the PM production.

Next, the operation of calculating the fuel adhesion ratio in the fuel adhesion ratio calculation processing unit 202 will be described with reference to FIG.
FIG. 12 is a flowchart showing the calculation operation of the fuel adhesion ratio in the fuel adhesion ratio calculation processing unit 202.

As shown in FIG. 12, the fuel adhesion ratio calculation processing unit 202 acquires the operating conditions of the internal combustion engine 2 (step S21). In the process of step S21, the fuel adhesion ratio calculation processing unit 202 acquires output information of various sensors, an operating amount of each actuator, and the like as operating conditions of the internal combustion engine 2. The sensor output information and the amount of operation include, for example, the exhaust valve timing θ _evic , the intake pressure Pi, the fuel pressure Pf which is the pressure applied to the fuel from the injector 27, the fuel injection start time θ _SOI , the fuel injection pulse ti, and the rotation speed Ne. Cooling water temperature Tw or the like.

The intake pressure Pi is the pressure at which the cylinder 21 flows into the cylinder 21a, and is acquired based on the measurement information measured by the intake pressure sensor 43. The rotation speed Ne is acquired based on the detection information of the crank angle sensor 29. The exhaust valve timing θ _evc is the opening / closing timing of the exhaust valve 25. The fuel injection pulse ti, fuel pressure P, and fuel injection start time θ _SOI are known as the control amount of the injector 27, and the exhaust valve timing θ _evc is known as the control amount of the injector 27 and the exhaust valve 25, respectively. Further, the cooling water temperature Tw is acquired from the cooling water sensor 28 provided in the cylinder 21.

Next, the fuel adhesion ratio calculation processing unit 202 determines the cylinder based on the exhaust valve timing θ _evic , the intake pressure Pi, the fuel pressure Pf, the fuel injection start time θ _SOI , the fuel injection pulse ti, the rotation speed Ne, and the cooling water temperature Tw. The ratio (fuel adhesion ratio) α of the amount of fuel adhering to the wall surface of the inner 21a and the crown surface 22a of the piston 22 is calculated (step S22). The fuel adhesion ratio α is calculated by the following formula 20. The rotation cycle tc is calculated by the above-mentioned equation 5 based on the rotation speed Ne.
[Equation 20]

As shown in Equation 20, the fuel adhesion ratio α is calculated as a function of the exhaust valve timing θ _evic , the intake pressure Pi, the fuel pressure Pf, the fuel injection start time θ _SOI , the fuel injection pulse ti, the rotation cycle tk, and the cooling water temperature Tw. be able to. As a result, the calculation operation of the fuel adhesion ratio α in the fuel adhesion ratio calculation processing unit 202 is completed.

6. Fuel Adhesion Control Factors Next, the fuel adhesion control factors in the in-cylinder injection type internal combustion engine 2 will be described.

The following factors can be considered as control factors for fuel adhesion in the in-cylinder injection type internal combustion engine 2. First, it is considered that the temperature and pressure of the air-fuel mixture in the cylinder 21a affect the penetration (injection distance) of the fuel as a factor of the state of the air-fuel mixture in the cylinder. Further, as a fuel distribution factor, it is considered that the closer the initial distribution of the injected fuel to the wall surface of the cylinder 21a and the crown surface 22a of the piston 22, the more the fuel adhesion increases. Then, as a fuel evaporation factor, it is considered that the wall surface temperature and the vaporization temperature affect the evaporation of the attached fuel.

[In-cylinder air-fuel mixture state factor]
First, the control factors of the in-cylinder air-fuel mixture state factors will be described.
Spray tip distance S is, the pressure difference [Delta] P L of the fuel pressure and ambient _gas, based on the elapsed time t after the ejection ambient gas density [rho _A, the fuel is calculated by the following equation 21.
[Equation 21]

As shown in Equation 21, the spray tip distance S is, the pressure difference [Delta] P L of the fuel pressure and ambient _gas, to be dependent on the ambient gas density [rho _A seen. Further, the relationship shown in the following equation 22 can be obtained from the gas state equation. In the formula 22, T is the temperature of the cylinder 21a, P is the pressure of the cylinder 21a, and R is the gas constant.
[Equation 22]

As shown in Equation 22, it can be seen that the injection tip distance S has a negative correlation with the pressure P of the ambient gas and has a sex correlation with the temperature T. One of the reasons why the temperature T of the cylinder 21a changes is that the amount of internal EGR (Exhaust Gas Recirculation) gas changes due to the operation of a variable valve timing mechanism (hereinafter referred to as VVT) or the like. .. For example, when the closing time of the exhaust valve 25 deviates from the bottom dead center, the residual amount of the combustion gas in the previous cycle increases, so that the temperature T in the cylinder 21a rises. As a result, as shown in Equation 22, the injection tip distance S becomes shorter.

Further, one of the causes of the change in the pressure P in the cylinder 21a is, for example, the change in the intake pressure due to the adjustment of the opening degree of the throttle valve 41 performed for controlling the intake air amount. For example, when the opening degree of the throttle valve 41 becomes small, the intake pressure decreases, and the pressure P in the cylinder 21a decreases. As a result, as shown in Equation 22, the injection tip distance S becomes longer.

From these, by using the exhaust valve timing θ _evic and the intake pressure Pi as variables, it is possible to calculate the change in fuel adhesion due to the temperature and pressure state of the air-fuel mixture in the cylinder 21a. As a result, the calculation accuracy of the fuel adhesion ratio α can be improved by the exhaust valve timing θ _evic and the intake pressure Pi.

[Fuel distribution factor]
Next, the control factor of the fuel distribution factor will be described with reference to FIG.
FIG. 13 is a diagram showing the position of the piston 22 and the state of fuel adhesion.

When examining the control factor of the fuel distribution factor, the relative positional relationship between the tip position of the injected fuel at the end time of fuel injection and the piston 22 is important. As shown in FIG. 13, when the fuel N1 is injected at a position where the distance between the piston 22 and the injector 27 is close, the injected fuel N1 reaches the crown surface 22a of the piston 22. Therefore, the fuel N3 adhering to the crown surface 22a of the piston 22 increases.

Further, when the fuel N1 is injected at a position where the distance between the piston 22 and the injector 27 is long, it is difficult for the injected fuel N1 to reach the crown surface 22a of the piston 22. Therefore, the fuel N3 adhering to the crown surface 22a of the piston 22 is reduced.

As shown in the above equation 22, the injection tip distance S is proportional to the fuel pressure Pf and the elapsed time t from the injection. Further, the elapsed time t from the injection can be calculated from the fuel injection pulse ti, which is the injection period. Therefore, the injection tip distance S can be calculated from the fuel injection pulse ti. Further, the position of the piston 22 is uniquely determined by the crank angle detected by the crank angle sensor 29.

From these, by using the fuel pressure pf and the fuel injection pulse ti as variables, it is possible to calculate the change in fuel adhesion due to the fuel distribution. As a result, the calculation accuracy of the fuel adhesion ratio α can be improved by the fuel pressure pf, the fuel injection pulse ti, and the rotation speed Ne.

[Fuel evaporation factor]
Next, the control factors of the fuel evaporation factor will be described.
The fuels N2 and N3 adhering to the wall surface of the cylinder 21a and the crown surface 22a of the piston 22 evaporate during the period from adhering to ignition. This evaporation period is proportional to the rotation period tc as shown by the above equation 14. Further, evaporation is promoted as the temperature of the wall surface of the cylinder 21a is higher. The temperature of the wall surface of the cylinder 21a largely depends on the cooling water temperature Tw. Therefore, by using the rotation cycle tk and the cooling water temperature Tw, it is possible to calculate the change in fuel adhesion due to the evaporation of the fuel. As a result, the calculation accuracy of the fuel adhesion ratio α can be improved by the rotation cycle tk and the cooling water temperature Tw.

7. Operation example of the temperature / pressure state calculation processing unit Next, an operation example of the temperature / pressure state calculation processing unit 203 will be described with reference to FIG.
FIG. 14 is a flowchart showing a temperature / pressure history calculation operation in the temperature / pressure state calculation processing unit 203.

As shown in FIG. 14, first, the temperature / pressure state calculation processing unit 203 acquires the operating conditions of the internal combustion engine 2 (step S31). In the process of step S31, the dispersion degree calculation processing unit 201 acquires output information of various sensors, an operation amount of each actuator, and the like as operating conditions of the internal combustion engine 2. Examples of the output information and the amount of operation of the sensor include the intake pressure Pi, the intake temperature Ti, and the in-cylinder volume V.

The intake air temperature Ti is the temperature of the air taken into the cylinder 21, and is acquired based on the measurement information measured by the intake air temperature sensor 44. The intake pressure Pi is the pressure at which the intake pressure Pi is taken into the cylinder 21, and is acquired based on the measurement information measured by the intake pressure sensor 43. The in-cylinder volume V is acquired based on the detection information of the crank angle sensor 29.

Next, the temperature / pressure state calculation processing unit 203 calculates the in-cylinder pressure (hereinafter referred to as the ignition timing in-cylinder pressure) _PADV at the ignition timing (step S32). In the process of step S32, the temperature / pressure state calculation processing unit 203 includes the intake pressure Pi, the in-cylinder volume V, the ignition timing in-cylinder volume V (θ _ADV ), and the in-cylinder volume at the time when the intake valve 24 is closed (hereinafter, intake air). The ignition timing in-cylinder pressure _PADV is calculated by the following equation 23 based on V (θ _IVC ) (called the valve closing timing in-cylinder volume).
[Equation 23]

The ignition timing in-cylinder volume V (θ _ADV ) and the intake valve closing timing in-cylinder volume V (θ _IVC ) may be preset constants. Further, the ignition timing cylinder internal volume V (θ _ADV ) and the intake valve closing timing tubular internal volume V (θ _IVC ) may be calculated for each cycle based on the detection information of the crank angle sensor 29. In this case, the accuracy of calculating the ignition timing in-cylinder pressure _PADV can be improved.

Next, the temperature / pressure state calculation processing unit 203 calculates the in-cylinder pressure history _Papp (step S33). In the process of step S33, the temperature / pressure state calculation processing unit 203 sets the following equation 24 and based on the ignition timing in-cylinder pressure P _ADV , the in-cylinder volume V, the ignition timing in-cylinder volume V (θ _ADV ), and the specific heat ratio γ. The in-cylinder pressure history _Papp is calculated by the equation 25.
[Equation 24]

[Equation 25]

Here, a and m are constants, Q _f is the total calorific value, and Δθ _burn is the combustion period. From

equations

24 and 25, the pressure inside the cylinder 21a can be calculated including during the combustion period. Further, the specific heat ratio γ may be a preset constant, or may be obtained by another method.

Next, the temperature / pressure state calculation processing unit 203 calculates the ignition timing temperature _TADV (step S34). In the process of step S34, the temperature / pressure state calculation processing unit 203 ignites based on the intake air temperature Ti, the ignition timing cylinder internal volume V (θ _ADV ), the intake valve closing timing tubular internal volume V (θ _IVC ), and the specific heat ratio. Calculate the timing temperature T _ADV .
[Equation 26]

Next, the temperature / pressure state calculation processing unit 203 calculates the product MR of the in-cylinder air mass and the gas constant based on the ignition timing in-cylinder pressure P _ADV , the ignition timing in-cylinder volume V (θ _ADV ), and the ignition timing temperature T _ADV . Then, the calculation is performed by the following equation 27 (step S35).
[Equation 27]

Next, the temperature / pressure state calculation processing unit 203 calculates the in-cylinder gas temperature history _Tave (θ), which is the temperature history of the air-fuel mixture in the in-cylinder 21a (step S36). In the process of step S36, the temperature / pressure state calculation processing unit 203 uses the following equation 28 to formulate the in-cylinder gas temperature based on the in-cylinder pressure history _Papp , the in-cylinder volume V, and the product MR of the in-cylinder air mass and the gas constant. The history _Tave (θ) is calculated.
[Equation 28]

As a result, the temperature / pressure history calculation operation in the temperature / pressure state calculation processing unit 203 is completed. As a result, the pressure in the cylinder 21a and the gas temperature in the cylinder of the air-fuel mixture, which change variously depending on the operating conditions, can be calculated, so that the PM calculation accuracy described later can be improved.

8. Operation Example of PM Emission Calculation Processing Unit Next, an operation example of the PM emission amount calculation processing unit 204 will be described with reference to FIGS. 15 to 18.
FIG. 15 is a graph showing the relationship between the air-fuel mixture ratio and the fuel concentration.

As mentioned above, the production of PM largely depends on the proportion of the air-fuel mixture. As shown in FIG. 15, the ratio of the air-fuel mixture largely depends on the generation of PM is mixture mixture due to the distribution resulting from the probability density function P ₁ and _(Z), the fuel deposition due probability density function due to fuel adhesion It increases at P ₂ (Z). The average reaction rate W (θ) [g / m ³ · s] of PM is determined by the following equation 20 according to the air-fuel mixture-induced probability density function P ₁ (Z) and the fuel adhesion-induced probability density function P ₂ (Z). Can be calculated.
[Equation 29]

Here, w ₁ is the reaction rate due to the air-fuel mixture [g / m ³ · s], w ₂ is the reaction rate due to fuel adhesion [g / m ³ · s], Z is the mixing fraction, and T is the temperature [K]. p is the pressure [pa].

The air-fuel mixture-induced probability density function P ₁ (Z) is calculated by the above equation 1. Further, the fuel adhesion-induced probability density function P ₂ (Z) is a fixed value set in advance as a probability density function having a certain size.

Further, in the cold state of the internal combustion engine 2, the influence of fuel adhesion has a large effect, and in the warm state of the internal combustion engine 2, the influence of the degree of dispersion of the air-fuel mixture distribution has a large effect. Therefore, as shown in Equation 29, the air-fuel mixture-induced probability density function P ₁ (Z) and the fuel adhesion-induced probability density function P ₂ (Z) are weighted by the fuel adhesion ratio α calculated by the above-mentioned equation 20. It is summed up. As a result, the ratio of the air-fuel mixture from the cold state to the warm state in the internal combustion engine 2 can be accurately detected.

Figure 16 shows the air-fuel mixture caused the reaction rate w ₁ map is a characteristic diagram showing an air-fuel mixture caused the reaction rate w ₁ on the map represented in that the gas mixture the reaction gas temperature distribution constant a. In FIG. 16, the reaction rate w1 caused by the air-fuel mixture _is mapped with the reaction gas temperature as the horizontal axis and the distribution constant a as the vertical axis. Further, FIG. 17 shows a fuel adhesion due kinetics w ₂ map is a characteristic diagram showing the relationship of the reaction gas temperature and fuel adhesion due kinetics w ₂ is the air-fuel mixture.
The characteristic diagrams shown in FIGS. 16 and 17 are created in advance and stored in a storage unit such as a ROM 103. Thus, it is possible to shorten the calculation time of the mixture resulting from the reaction rate w ₁ and the fuel deposition due kinetics w _2.

Next, the operation of calculating the PM emission amount in the PM emission amount calculation processing unit 204 will be described with reference to FIG.
FIG. 18 is a flowchart showing a PM emission amount calculation operation in the PM emission amount calculation processing unit 204.

As shown in FIG. 18, the PM emission amount calculation processing unit 204 calculates the distribution constant a (step S41). In the process of step S41, the PM emission amount calculation processing unit 204 uses the distribution constant a from the above equation 3 based on the in-cylinder average value _Zave of the mixed fraction and the variance σ calculated by the dispersion degree calculation processing unit 201. Is calculated.

Next, the PM emission amount calculation processing unit 204 calculates the air-fuel mixture-induced reaction rate w ₁ and the fuel adhesion-induced reaction rate w ₂ (step S42). In the process of step S42, the PM emission calculation processing unit 204 uses the maps shown in FIGS. 16 and 17 based on the distribution constant a calculated in the process of step S41 and the reaction gas temperature Tb, and causes the air-fuel mixture. The reaction rate w ₁ and the reaction rate w ₂ due to fuel adhesion are calculated. The reaction gas temperature Tb is obtained from the in-cylinder gas temperature history _Tave (θ) calculated by the temperature / pressure state calculation processing unit 203.

Next, the PM emission amount calculation processing unit 204 calculates the PM emission amount (step S43). In step S43, PM emission amount calculation processing section 204 first calculates the average reaction rate W of the PM from the equation 29 described above ^{(θ) [g / m 3} · s]. Next, the PM emission amount calculation processing unit 204 integrates the average reaction rate W (θ) of PM with the crank angle θ from the ignition timing θ _ADV to the exhaust valve opening timing θ _EVO , as shown in the following equation 30.
[Equation 30]

Then, according to the formula 30, the PM emission amount calculation processing unit 204 can calculate the PM emission amount PMcycle [g] per cycle. Next, the PM emission amount calculation processing unit 204 calculates the PM concentration PMout [g / m ³ ] in the standard state (25 ° C., 100 kPa) by the following formula 31. Further, as shown in Equation 31, the calculation of PM concentration PMout [g / ^{m 3],} the in-cylinder pressure history _{P app} of temperature and pressure state calculation processing unit 203 is calculated is used.
[Equation 31]

As a result, the PM emission amount calculation operation in the PM emission amount calculation processing unit 204 is completed.
In this way, by using the degree of dispersion σ of the air-fuel mixture distribution and the fuel adhesion ratio α, the reaction rate and PM emission of PM from the cold state to the warm state in the internal combustion engine 2 can be accurately estimated. .. When the internal combustion engine 2 is in the cold state, the reaction rate of PM and the amount of PM emission may be calculated using only the fuel adhesion ratio α and the fuel adhesion cause probability density function P ₂ (Z), or the internal combustion engine 2 may calculate. the warm-up state, the degree σ scattered the mixture distribution, using only the gas mixture resulting from the probability density function P _{1 (Z),} it may be calculated reaction rate and PM emissions PM.

9. Operation Example of PM Accumulation Amount Calculation Processing Unit Next, an operation example of the PM deposition amount calculation processing unit 205 will be described with reference to FIGS. 19 to 22.
FIG. 19 is a schematic view showing the internal state of the GPF 35 and the PM flowing into the GPF 35.

As shown in FIG. 19, PM flows into the GPF 35 together with the exhaust gas. Then, the GPF 35 collects PM by the filter unit 35a provided inside. Further, the PM collected in GPF35 disappears by combustion. Therefore, the amount of PM deposited on the GPF35 (PM deposition amount) is based on the amount of PM collected by the GPF35 (PM collection amount) and the amount of PM extinguished by combustion (PM combustion amount) as follows. Is calculated as follows.
PM accumulation amount = PM collection amount-PM combustion amount

Next, the operation of calculating the PM deposit amount in the PM deposit amount calculation processing unit 205 will be described with reference to FIGS. 20 to 22.
FIG. 20 is a flowchart showing a PM accumulation amount calculation operation in the PM accumulation amount calculation processing unit 205. FIG. 21 is a characteristic diagram showing the relationship between the upstream temperature of GPF35 and the PM combustion rate, and FIG. 22 is a characteristic diagram showing the relationship between the excess air ratio and the PM combustion rate correction coefficient A.

As shown in FIG. 20, first, the PM accumulation amount calculation processing unit 205 calculates the amount of PM flowing into the GPF 35 (step S51). In the process of step S51, PM accumulation amount calculation processing section 205, the PM concentration PMout the PM emission amount calculation processing section 204 calculates [g / ^{m 3],} based on the exhaust gas flow _{^{Q EXH [m 3 / s]}} , The PM inflow amount PM _usGPF [g / s] is calculated by the following formula 32.
[Equation 32]

The exhaust flow rate Q _EXH [m ³ / s] is obtained from the intake air amount Q _in [m ³ / s] measured by the air flow sensor 42 attached to the intake pipe 31.

Next, the PM deposition amount calculation processing unit 205 calculates the amount of PM collected in the GPF 35, that is, the PM collection amount (step S52). In the process of step S52, PM accumulation amount calculation processing section 205 based on the PM inflow _{PM usGPF} [g / s] and PM trapping efficiency eta _adp, PM collecting quantity PMadp [g / s] of the following formula 33 Calculated by
[Equation 33]

The PM collection efficiency η _app is preset and stored in the ROM 103.

Next, the PM accumulation amount calculation processing unit 205 acquires the PM combustion rate Vburn [g / s] based on the PM combustion rate map preset and stored in the ROM 103 and the upstream temperature of the GPF 35 (step S53). .. The upstream temperature [K] of the GPF 35 is a temperature detected by the GPF upstream temperature sensor 47 provided on the upstream side of the GPF 35.

The PM combustion speed map is shown in FIG. In FIG. 21, the horizontal axis shows the upstream temperature of GPF35, and the vertical axis shows the PM combustion rate. As shown in FIG. 21, the PM combustion rate increases as the upstream temperature of the GPF 35 rises.

Next, the PM deposition amount calculation processing unit 205 acquires the correction coefficient A (step S54). In the process of step S54, the PM accumulation amount calculation processing unit 205 has the PM combustion rate correction coefficient map preset and stored in the ROM 103, and the air excess rate λ detected by the air-fuel ratio sensor 46 provided in the exhaust pipe 32. Based on, the PM combustion rate correction coefficient A is acquired.

The PM combustion speed correction coefficient map is shown in FIG. In FIG. 22, the horizontal axis shows the excess air ratio λ, and the vertical axis shows the PM combustion rate correction coefficient A. Considering that the PM combustion rate increases due to the increase in the oxygen concentration in the exhaust gas, as shown in FIG. 22, in the PM combustion rate correction coefficient map, the PM combustion rate correction coefficient increases as the excess air ratio λ increases. A is increasing.

Next, the PM accumulation amount calculation processing unit 205 calculates the PM combustion amount (step S55). In the process of step S55, the PM accumulation amount calculation processing unit 205 uses the PM combustion rate Vburn [g / s] per second and the PM combustion rate correction coefficient A to determine the PM combustion amount PMburn [g / s]. It is calculated by the following formula 34.
[Equation 34]

Next, the PM deposit amount calculation processing unit 205 calculates the PM deposit amount (step S55). In the process of step S55, the PM accumulation amount calculation processing unit 205 sets the PM accumulation amount PMload (n) in the nth cycle (current cycle) to the PM accumulation amount PMload (n-1) in the n-1 cycle (pre-cycle). ), PM collection amount PMadp, PM combustion amount PMburn, and unit time Δt, calculated from the following equation 35.
[Equation 35]

As a result, the operation of calculating the PM accumulation amount in the PM accumulation amount calculation processing unit 205 is completed.
The PM emission amount calculation processing unit 204 described above can calculate an accurate PM emission amount, and further, by calculating the PM collection amount collected by the GPF35 and the PM combustion amount burned inside the GPF35, the GPF35 can be obtained. The amount of PM deposited can be calculated accurately.

10. Operation example of the reproduction control processing unit Next, the determination operation of the reproduction control command in the reproduction control processing unit 206 will be described with reference to FIG.
FIG. 23 is a flowchart showing a determination operation of the reproduction control command in the reproduction control processing unit 206.

As shown in FIG. 23, the reproduction control processing unit 206 determines whether or not to perform reproduction control (step S61). In the process of step S61, when the reproduction control processing unit 206 determines that the reproduction control is not performed (NO determination in step S61). Then, the reproduction control processing unit 206 ends the determination operation.

Further, in the process of step S61, when it is determined that the reproduction control is performed (YES determination in step S61), the reproduction control processing unit 206 outputs a reproduction control command (step S62). As a result, the determination operation of the reproduction control command in the reproduction control processing unit 206 is completed.

In the determination process of step S61, the regeneration control processing unit 206 determines whether or not the PM accumulation amount PM load calculated by the PM accumulation amount calculation processing unit 205 described above exceeds the PM accumulation allowance stored in the ROM 103 or the like. to decide. Further, in the determination process of step S61, the reproduction control processing unit 206 determines whether or not the temperature measured by the GPF upstream temperature sensor 47 exceeds the GPF allowable temperature in which the ROM 103 or the like is stored.

Further, as the regeneration control command in step S62, for example, when the PM deposit amount exceeds the PM deposit amount allowable amount, the regeneration control processing unit 206 issues a lean burn control command and a fuel cut prohibition command. The lean burn control command is a command that controls the throttle valve 41 and the injector 27 so that the combustion exceeds the ideal air-fuel ratio. Further, the fuel cut prohibition command is a command for controlling the injector 27 and prohibiting the stop of the fuel supply to the cylinder 21a of the cylinder 21. By these commands, it is possible to prevent the temperature of the GPF 35 from becoming higher than the GPF failure temperature and prevent the GPF 35 from being damaged.

As described above, according to the internal combustion engine control device 10 of this example, the amount of PM flowing into the GPF 35 is accurately calculated in consideration of the degree of dispersion σ of the air-fuel mixture distribution, the fuel adhesion ratio α, and the reaction gas temperature Tb. can do. As a result, the regeneration control of the GPF 35 can be performed at an appropriate timing, and it is possible to prevent the GPF 35 from being damaged due to excessive accumulation of PM.

It should be noted that the embodiment is not limited to the embodiment described above and shown in the drawings, and various modifications can be carried out within a range that does not deviate from the gist of the invention described in the claims.

2 ... Internal combustion engine, 10 ... Internal combustion engine controller, 21 ... Cylinder, 21a ... In-cylinder, 22 ... Piston, 22a ... Crown surface, 23 ... Crank shaft, 24 ... Intake valve, 25 ... Exhaust valve, 26 ... Ignition plug, 27 ... Injector, 28 ... Cooling water sensor, 29 ... Crank angle sensor, 31 ... Intake pipe, 32 ... Exhaust pipe, 33 ... EGR pipe, 34 ... Three-way catalyst, 35 ... Gasoline party cute filter (PM collection filter), 41 ... Throttle valve, 42 ... Airflow sensor, 43 ... Intake pressure sensor, 44 ... Intake temperature sensor, 45 ... EGR valve, 46 ... Air fuel ratio sensor, 47 ... GPF upstream temperature sensor, 48 ... Differential pressure sensor, 101 ... CPU ( Control unit), 102 ... RAM, 103 ... ROM (storage unit), 104 ... input / output port, 105 ... input circuit (reception unit), 110 ... GPF control unit (control unit), 201 ... scatter degree calculation processing unit, 202 ... Fuel adhesion ratio calculation processing unit, 203 ... Temperature and pressure state calculation processing unit, 204 ... PM emission amount calculation processing unit, 205 ... PM accumulation amount calculation processing unit, 206 ... Regeneration control processing unit

Claims

A cylinder, a piston that slides in the cylinder of the cylinder, a crankshaft connected to the piston, an injector that injects fuel into the cylinder of the cylinder, and a mixture of air and the fuel in the cylinder. In an internal combustion engine control device that controls an internal combustion engine having a spark plug for igniting qi.
The ignition timing at which the spark plug ignites the air-fuel mixture in the cylinder and the fuel injection start timing at which the injector starts fuel injection into the cylinder are acquired, and based on the ignition timing and the fuel injection start timing. An internal combustion engine control device including a control unit for calculating the degree of dispersion of the air-fuel mixture distribution in the cylinder.
The control unit acquires a fuel injection pulse which is a period during which fuel is injected from the injector, and in addition to the ignition timing and the fuel injection start timing, the distribution of the air-fuel mixture is based on the fuel injection pulse. The internal combustion engine control device according to claim 1, wherein the degree of scattering is calculated.
The control unit acquires the rotation speed of the crankshaft and calculates the degree of dispersion of the air-fuel mixture distribution based on the ignition timing, the fuel injection start timing, the fuel injection pulse, and the rotation speed. The internal combustion engine control device according to claim 2.
The control unit acquires the opening / closing timing of the exhaust valve arranged so as to open / close the exhaust port of the cylinder and the intake pressure which is the pressure of the air taken into the cylinder, and the opening / closing timing of the exhaust valve and the intake pressure. The internal combustion engine control device according to claim 1, wherein the fuel adhesion ratio, which is the ratio of the amount of the fuel adhered to the wall surface in the cylinder and the crown surface of the piston, is calculated based on the above.
The control unit acquires the rotation speed of the crankshaft and the temperature of the cooling water for cooling the cylinder, and is based on the rotation speed and the temperature of the cooling water in addition to the opening / closing timing of the exhaust valve and the intake pressure. The internal combustion engine control device according to claim 4, wherein the fuel adhesion ratio is calculated.
The control unit acquires the fuel pressure which is the pressure applied to the fuel by the injector and the fuel injection pulse which is the period during which the fuel is injected from the injector, and the opening / closing timing of the exhaust valve, the intake pressure, and the rotation. The internal combustion engine control device according to claim 5, wherein the fuel adhesion ratio is calculated based on the fuel pressure, the fuel injection start timing, and the fuel injection pulse in addition to the number and the temperature of the cooling water.
The internal combustion engine control device according to claim 1, wherein the control unit calculates the amount of particulate matter discharged from the cylinder based on the calculated degree of dispersion of the air-fuel mixture distribution.
The internal combustion engine control device according to claim 4, wherein the control unit calculates the amount of particulate matter discharged from the cylinder based on the calculated degree of dispersion of the air-fuel mixture distribution and the fuel adhesion ratio.
The internal combustion engine control device according to claim 7 or 8, wherein the control unit calculates the average reaction rate of the particulate matter, and calculates the emission amount of the particulate matter from the calculated average reaction rate.
The control unit acquires the intake air temperature, which is the temperature of the air taken into the cylinder, the intake pressure, which is the pressure of the air taken into the cylinder, and the in-cylinder volume in the cylinder, and the intake temperature and the intake pressure. The internal combustion engine control device according to claim 9, wherein the temperature history of the air-fuel mixture in the cylinder and the pressure history in the cylinder are calculated based on the in-cylinder volume.
The internal combustion engine control device according to claim 10, wherein the control unit calculates an emission amount of the particulate matter from the calculated temperature history of the air-fuel mixture.
The control unit calculates the accumulated amount of the particulate matter deposited on the PM collection filter for collecting the particulate matter provided in the internal combustion engine based on the calculated emission amount of the particulate matter. The internal combustion engine control device according to claim 7 or 8.
The internal combustion engine according to claim 12, wherein the control unit determines whether or not to output a regeneration control command for removing the particulate matter from the PM collection filter based on the calculated accumulated amount of the particulate matter. Engine control device.
A cylinder, a piston that slides in the cylinder of the cylinder, a crankshaft connected to the piston, an injector that injects fuel into the cylinder of the cylinder, and a mixture of air and the fuel in the cylinder. In an internal combustion engine control device that controls an internal combustion engine having a spark plug for igniting qi.
The opening / closing timing of the exhaust valve arranged so as to open / close the exhaust port of the cylinder and the intake pressure which is the pressure of the air taken into the cylinder are acquired, and based on the opening / closing timing of the exhaust valve and the intake pressure, the said An internal combustion engine control device including a control unit that calculates a fuel adhesion ratio, which is a ratio of the amount of the fuel adhering to the wall surface of the cylinder and the crown surface of the piston.