JP2864975B2 - Control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an internal combustion engine (engine).
The present invention relates to a control device for an internal combustion engine for controlling an engine by evaluating a combustion state including a lean combustion limit and the like.

[0002]

2. Description of the Related Art In general, when an air-fuel ratio of an air-fuel mixture supplied to an engine is made lean (lean) and the air-fuel ratio is made to burn lean,
As shown in FIG. 19, it is known that the NOx generation amount in the lean combustion region is significantly reduced by the above-described leaning. Therefore, from the viewpoint of NOx reduction,
It is effective to operate the engine with the set air-fuel ratio further on the lean limit side.

In view of the above, various lean burn engines have been proposed in which the air-fuel ratio is made leaner and lean burn is performed as described above with the aim of improving both fuel efficiency and reducing NOx. In such a lean burn engine, the air-fuel ratio feedback control is generally performed using a linear air-fuel ratio sensor (LAFS).

[0004]

However, in the above-described lean burn engine, the target air-fuel ratio is set to about 1.5 to 2 in air-fuel ratio below the lean limit in consideration of engine and sensor variations or environmental factors. It is set on the rich side, which leaves room for further improvement in terms of fuel efficiency reduction and NOx reduction.

By the way, techniques for approaching the lean limit have been proposed in the past, and the following technique has been proposed as one of the techniques. That is, a method in which an in-cylinder pressure (combustion chamber pressure) is detected, an engine output torque is calculated from these in-cylinder pressures, and a fluctuation in combustion is detected using the calculated value (Japanese Patent Laid-Open No. 2-153243). And Japanese Patent Application Publication No. 3-37021 and Japanese Patent Application Publication No. 3-50100, which perform air-fuel ratio correction based on the detection result of combustion fluctuation.

However, according to these means, the enrichment and the subsequent leaning are performed each time a deteriorated state is detected. This means that the control operation is performed based on the detected single combustion deterioration data. With such a means, there is a possibility that a limit cycle of the air-fuel ratio may occur, and when such a state appears, Drivability, fuel economy and exhaust gas limit performance cannot be achieved.

[0007] Regarding such a problem, when controlling,
It is necessary to have a viewpoint that the fluctuation of combustion is stochastic. The present invention has been made in view of such a problem, and enables drivability, fuel efficiency, and the limit performance of exhaust gas by enabling the engine to be controlled using two types of control information correlated with combustion fluctuation. It is an object of the present invention to provide a control device for an internal combustion engine that can be realized.

[0008]

For this purpose, a control apparatus for an internal combustion engine according to the present invention (claim 1) includes a parameter detecting means for detecting a parameter indicating an output state of the internal combustion engine, and a parameter detecting means for each combustion of the internal combustion engine. A combustion index data calculating means for calculating combustion index data correlated with the combustion fluctuation based on the parameter value, and comparing the combustion index data with a combustion deterioration determination threshold value to control a combustion fluctuation adjusting element of the internal combustion engine for each combustion First control information calculating means for calculating first control information for performing the control, and second control information for controlling the combustion fluctuation adjusting element by performing statistical processing on the combustion index data during a set sampling period. And a control means for controlling the combustion fluctuation element using the first control information and the second control information. It is set to.

In the control apparatus for an internal combustion engine according to the present invention, the control width of the combustion variable element based on the second control information is larger than the control width of the combustion variable element based on the first control information. It is characterized in that each of the first control information and the second control information has a limit value so as to be wider. Further, the control device for an internal combustion engine according to the present invention (claim 3) detects that the operation state of the internal combustion engine has reached a preset first operation state, and the first control information calculation means detects the operation state. The first control information is calculated, and the second control information calculation by the second control information calculation means is performed when another situation is satisfied in the first operation state. It is characterized by:

The control device for an internal combustion engine of the present invention (claim 4) integrates control data when the combustion index data exceeds a threshold value for judging combustion deterioration to the combustion deterioration side, and accumulates the integrated data. The integrating means for obtaining an index is the second
In the control information calculation means. Further, a control device for an internal combustion engine according to the present invention (Claim 5)
The above-mentioned parameter detecting means is configured as means for detecting pressure information in the combustion chamber, and converts the pressure information in the combustion chamber at two different points in the compression stroke of the internal combustion engine into pressure information in the first combustion chamber and pressure in the second combustion chamber. When the information on the pressure in the combustion chamber during the expansion stroke of the internal combustion engine is the pressure information on the third combustion chamber, the above-mentioned combustion index data calculating means calculates the pressure information on the third combustion chamber and the pressure information on the first and second combustion chambers. And the difference between the pressure information of one of the combustion chambers and
It is characterized in that it is configured as means for calculating the combustion index data by calculating a ratio with the difference between the pressure information of the second combustion chamber.

In the control apparatus for an internal combustion engine according to the present invention, the parameter detecting means is configured as means for detecting data indicating a rotation state of a rotating shaft driven by combustion of the internal combustion engine. It is characterized by:

[0012]

In the control apparatus for an internal combustion engine according to the present invention, a parameter representing an output state of the internal combustion engine is detected by the parameter detection means, and the combustion index data calculation means performs the above-described operation for each combustion of the internal combustion engine. Based on the parameter value, combustion index data correlated with the combustion fluctuation is calculated. Then, the first control information for comparing the combustion index data with the combustion deterioration determination threshold value and controlling the combustion fluctuation adjustment element of the internal combustion engine for each combustion is calculated by the first control information calculation means, Statistical processing is performed on the combustion index data in the set sampling period, and second control information for controlling the combustion fluctuation adjustment element is calculated by the second control information calculation means. Further, the combustion fluctuation element is controlled by the control means using the first and second control information.

In the control apparatus for an internal combustion engine according to the present invention, the control range of the combustion variation element based on the first control information is determined by the limit value provided for each of the first and second control information. Thus, the control is performed in a state where the control range of the combustion variation element by the second control information is wide. Also,
In the control apparatus for an internal combustion engine according to the present invention (claim 3), the first control information calculating means detects that the operating state of the internal combustion engine has reached a preset first operating state, and the first control information calculating means performs the first control information calculating means. The control information is calculated, and when another situation is established in the first operation state, the second control information calculation means performs the second control information calculation.

In the control device for an internal combustion engine according to the present invention (claim 4), the control data when the combustion index data exceeds the combustion deterioration determination threshold value to the combustion deterioration side is sent to the second control information calculation means. The integration is provided by the provided integration means, and a combustion deterioration index is obtained. Furthermore, in the control device for an internal combustion engine of the present invention (claim 5), the parameter detection means detects the pressure information in the combustion chamber, and converts the pressure information at two different points in the compression stroke of the internal combustion engine. The first combustion chamber pressure information and the second combustion chamber pressure information are used, and the combustion chamber pressure information during the expansion stroke of the internal combustion engine is stored in the third combustion chamber.
In the case where the pressure information is the combustion chamber pressure information, the difference between the third combustion chamber pressure information and one of the first and second combustion chamber pressure information and the first combustion chamber pressure information is calculated by the combustion index data calculation means. , And the ratio to the difference in the pressure information of the second combustion chamber is calculated.

In the control device for an internal combustion engine according to the present invention (claim 6), the parameter detecting means detects data indicating a rotation state of a rotary shaft driven by combustion of the internal combustion engine.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 18 show a control device for an internal combustion engine as an embodiment of the present invention, and FIGS. The control block diagram, FIG. 3 is a schematic configuration diagram of an engine system equipped with the present apparatus, FIGS. 4 to 10 are flowcharts illustrating the control procedure, and FIG. 11 illustrates pressure measurement points used for calculating a combustion index. FIG. 12 is a diagram illustrating the relationship between the combustion fluctuation near the lean limit and the crank angle, FIG. 13 is a diagram illustrating the correlation between the combustion index near the lean limit and the engine output, and FIG. , Engine output and engine speed, and FIGS. 15 to 18 are diagrams illustrating combustion fluctuation characteristics of the engine.

FIG. 3 shows an engine system having the present apparatus. In FIG. 3, an engine (internal combustion engine) EG has an intake passage 2 and an exhaust passage 3 leading to a combustion chamber 1 thereof. The communication between the intake passage 2 and the combustion chamber 1 is controlled by an intake valve 4, and the communication between the exhaust passage 3 and the combustion chamber 1 is controlled by an exhaust valve 5.

Further, an air cleaner, a throttle valve (both not shown), and an electromagnetic fuel injection valve (injector) 6 are provided in the intake passage 2 in this order from the upstream side, and the exhaust passage 3 has an upstream side thereof. An exhaust gas purifying catalytic converter and a muffler (muffler) (both not shown) are provided in order from the side. The intake passage 2 is provided with a surge tank 2a.
Are provided in the intake port portion corresponding to each cylinder.

An exhaust gas recirculation passage (EGR passage) 7 is interposed between the intake passage 2 and the exhaust passage 3, and an electromagnetic EGR valve 8 is interposed in the EGR passage 7. Have been. Reference numeral 18 denotes a spark plug. further,
Various sensors are provided to control the engine EG. First, an in-cylinder pressure sensor 17 for detecting the pressure in the combustion chamber 1 (in-cylinder pressure: combustion chamber pressure) is provided, and a crank angle sensor 15 for detecting a crank angle is further provided.
(The crank angle sensor 15 also serves as a rotation speed sensor for detecting the engine rotation speed).

On the intake passage 2 side, an air flow sensor (intake amount sensor) 9 for detecting an intake air amount from Karman vortex information, an intake air temperature sensor 10 for detecting intake air temperature, and a large An atmospheric pressure sensor 11 for detecting the atmospheric pressure is provided, and a potentiometer type throttle sensor 12 for detecting the opening of the throttle valve is provided at a portion where the throttle valve is provided.

Further, on the exhaust passage 3 side, an air-fuel ratio sensor (or a linear air-fuel ratio sensor) 13 for detecting the oxygen concentration (O ₂ concentration) in the exhaust gas is provided on the upstream side of the catalytic converter.
(Hereinafter, sometimes simply referred to as “O ₂ sensor 13”). As other sensors, a water temperature sensor 14 for detecting an engine cooling water temperature and a TDC sensor (cylinder discrimination sensor) 16 for detecting a top dead center of the first cylinder (reference cylinder) are also provided.

The detection signals from these sensors are input to an electronic control unit (ECU) 20, which has a CPU, ROM,
AM, an appropriate input / output interface, and when a detection signal from each of the above-described sensors is input to the CPU of the ECU 20, a required calculation is performed by the CPU, and the fuel injection amount control based on the calculation result is performed. A signal (fuel amount control signal), an ignition timing control signal, and an EGR control signal are output to the injector 6, the ignition plug 18, and the EGR valve 8, respectively.

Attention is now directed to fuel injection control (air-fuel ratio control). The ECU 20 outputs a fuel injection amount control signal calculated by a method described later to the injector 6, and the ECU 6 outputs the fuel injection amount control signal according to the fuel injection amount control signal. Is the fuel injection time T _inj (= Tb × Kafl × K × (1 + Kfb + Kc) ±
Tacc + Td). Here, Tb is a basic drive time, and this basic drive time Tb
Is determined according to information on the amount of intake air per one rotation of the engine obtained from the air flow sensor 9 and the crank angle sensor 15.

Kafl is a leaning correction coefficient, which is obtained from a map (storage means) according to engine load information obtained from the air flow sensor 9 and the like. Is set to “1” at the time of the stoichiometric air-fuel ratio (Stonkio). Kfb is a feedback correction coefficient, and the feedback correction coefficient Kfb is set based on a combustion index Ci described later.

Kc is a cylinder pressure correction coefficient, and the cylinder pressure correction coefficient Kc is set based on a combustion deterioration index Vc described later. K is another correction coefficient. The correction coefficient K is set according to the atmospheric pressure correction coefficient set according to the atmospheric pressure obtained by the atmospheric pressure sensor 11, and set according to the intake air temperature obtained by the intake air temperature sensor 10. Intake air temperature correction coefficient, water temperature sensor 1
An engine cold correction coefficient set in accordance with the engine cooling water temperature obtained in step 4 is considered.

Tacc is an acceleration / deceleration correction time, and the acceleration / deceleration correction time Tacc is a time set according to the acceleration / deceleration state of the engine obtained from the throttle sensor 12. Td
Is wasted time. Next, a method of obtaining the feedback correction coefficient Kfb based on the combustion index Ci newly defined in the present invention will be described.

First, the ECU 20 controls the in-cylinder pressure sensor 17,
From the signal from the crank angle sensor 15, two points of the compression stroke,
A total of three in-cylinder pressures, one for the expansion stroke, are measured. That is, as shown in FIG. 1, the ECU 20 has a function of an in-cylinder pressure detecting means 21 for measuring a total of three in-cylinder pressures of two compression strokes and one expansion stroke. In the means 21, specifically, the in-cylinder pressure P120B (first combustion chamber pressure) at 120 ° before the top dead center during the compression stroke of the internal combustion engine after the intake and exhaust valves are closed, and the pressure after the in-cylinder pressure P120B Timing but before the ignition timing (before top dead center 60
°) in-cylinder pressure during the compression stroke of the internal combustion engine at P60B
(Second pressure in the combustion chamber) and the in-cylinder pressure P60 at 60 ° after the top dead center during the expansion stroke of the internal combustion engine when the combustion is almost completed.
A (the pressure in the third combustion chamber) is detected at three points in the cylinder. FIG. 1 or FIG. 11 shows the measurement points of the in-cylinder pressures P120B, P60B, and P60A at three points, that is, two points of the compression stroke and one point of the expansion stroke.

The ECU 20 includes an in-cylinder pressure detecting means 21
In-cylinder pressures P120B, P60B, P
It has a function of a combustion index calculating means 22 for calculating a combustion index Ci defined by the following equation from 60A. Ci = (P60A-P60B) / (P60B-P120
B) (1) That is, the combustion index Ci is defined by the ratio of the difference between P60A and P60B and the difference between P60B and P120B.

Here, the denominator (P60) of this combustion index Ci
BP120B) has information on the amount of air (including the amount of EGR) into the combustion chamber 1 since it has the compression pressure information, and the numerator (P60A-P60) of the combustion index Ci.
B) has the information of the engine output because it has the expansion pressure fluctuation information, and therefore, the combustion index Ci becomes
It will have information on the engine output per unit air volume. The calculation may be performed using P150B instead of P120B.

The combustion index Ci is a combustion index C calculated by a combustion index data calculation means 101 described later.
i may be used. Further, the ECU 20 has a function of a comparing means 23 for calculating a deviation ΔCi between the combustion index Ci obtained by the combustion index calculating means 22 and a reference combustion index (set value: threshold value) Cio.

Further, the ECU 20 has a function of a converting means 24 for giving a dead zone and a weight as shown by a characteristic F in FIG. 1 to the deviation ΔCi obtained by the comparing means 23. 24 has a function of accumulating means 25 for accumulating the output F (ΔCi) of the
Also has a function of a limiter means 26 for performing limiter processing on the output of
A feedback correction coefficient Kfb as a first control coefficient (first control information) is determined. That is, during the air-fuel ratio feedback operation, while the output of the accumulating means 25 does not exceed the upper limit or the lower limit, the output of the accumulating means 25 exceeds the upper or lower limit according to the accumulated output from the accumulating means 25. Then, the feedback correction coefficient Kfb is updated so that the air-fuel ratio is adjusted according to the upper limit value or the lower limit value.

The feedback correction coefficient Kfb as the first control coefficient is compared with a statistical learning correction coefficient Kc as a second control coefficient (second control information) described later due to the limit value of the limiter means 26. The control width is made small, so that excessive control of the feedback control can be prevented against sudden deterioration of the combustion index Ci due to noise or the like which does not indicate the current combustion state.

When the air-fuel ratio is not in the feedback operation region (steady operation region), the ECU 20 stops updating the feedback correction coefficient Kfb, and detects that the first operation state has been set in advance and performs the first operation state. It has a feedback determination switch means 27 for calculating a feedback control coefficient Kfb as one control coefficient. The feedback determination switch means 27
Has a feedback determination logic unit 27A and a switch unit 27B.

Here, the first operation state is a case where the following operation conditions are satisfied. Being in lean burn operation. The engine acceleration is lower than a predetermined value (about 100 rpm / s). The accelerator operation speed is not more than a predetermined amount (about 5 ° / s). The sensor is normal.

When such conditions are used as a criterion and the conditions are satisfied, steady-state operation is being performed and lean feedback control is to be performed. Therefore, a feedback control coefficient Kfb is calculated, and correction is performed using the control coefficient Kfb. Fuel injection is performed. In addition,
The above condition determination is configured to be reset at the start of feedback control or every predetermined cycle.

In order to confirm that the combustion index Ci has information on the engine output per unit air amount, the present inventor has found that the engine output (or engine misfire state) when the engine is operated near the lean combustion limit is determined. And the above-mentioned combustion index Ci. FIG. 12 (a)
FIG. 13 (a) shows the combustion index and engine output characteristics when the combustion is stable, and FIG. 12 (b) shows the results when the combustion is stable when the combustion is stable. 13 shows the crank angle / combustion fluctuation characteristics of FIG.
(B) is a combustion index / engine output characteristic in the case of the lean combustion limit, FIG. 12 (c) is a crank angle / combustion variation characteristic in the case where the lean combustion limit is exceeded, and FIG. The characteristics of the combustion index and the engine output in the case of exceeding the above are seen from the characteristic diagrams as follows. 12 (a) to 12 (c) show the characteristics of the maximum value and the minimum value of the parameter fluctuation, that is, the envelope characteristics of all the parameter fluctuations, and the area enclosed by the envelope characteristics. The smaller the value, the more stable the combustion.

First, when combustion is stable, a certain value Cio (this value Cio) is obtained at a substantially constant engine output.
(Corresponding to the above-mentioned "threshold value"). When the lean combustion limit is reached, the combustion index Ci begins to slightly disperse. When the lean combustion limit is exceeded, the combustion index Ci disperses to a portion where the engine output is low, and the combustion index Ci for a portion where the engine output is low is reduced. It can be seen that the value is below the threshold value Cio.

From this, it can be seen that the combustion index Ci has a strong correlation with the engine output, and when the combustion index Ci falls below the threshold value Cio, the engine output decreases and the lean combustion limit is exceeded. It turns out that evaluation can be performed. FIG. 14 is a graph showing the relationship between the engine speed, the engine output, and the combustion index when the engine is operated under various operating conditions. It can be seen that it shows a substantially constant value irrespective of the state, and that when the fuel is cut during deceleration and the engine output decreases, the combustion index also decreases in conjunction with this.

That is, it has been proved that there is a very strong correlation between the combustion index Ci and the engine output. Therefore, near the lean combustion limit, a cycle in which the combustion index Ci is small starts to appear, and when approaching the lean limit, the output of the accumulating means 25 (integration information of the deviation) increases.
When the feedback correction coefficient Kfb is updated so as to enrich the air-fuel ratio in response to this, the misfire rate decreases, the combustion index Ci increases again, and the magnitude of the deviation integration information decreases.

As described above, the ECU 20 adjusts the air-fuel ratio as an engine combustion fluctuation adjusting element in a direction in which the magnitude of the accumulated information decreases based on the accumulated information of the deviation ΔCi obtained by the comparing means 23. It will also have the function of the control means for controlling the elements. In order to perform the above control, the combustion state of the engine is also evaluated based on the combustion index Ci.
It also has a function of an evaluation means for evaluating the combustion state of the engine based on the combustion index Ci.

Next, a method of obtaining a learning control correction coefficient Kc as a second control coefficient based on the combustion deterioration index Vc newly defined in the present invention will be described. here,
The learning control correction coefficient Kc is used to calculate the fuel injection time Tinj, is set by detecting a statistical combustion fluctuation, and is configured to be updated every predetermined sampling period. Further, a learning control determination switch means 201 is provided so that the calculation of the learning control correction coefficient Kc is performed when a predetermined situation is established, in addition to the determination conditions for the first operation state described above. ing. The learning control determination switch means 201 includes a learning control determination logic unit 201A and a switch unit 201B.

The predetermined condition determined by the learning control determination switch means 201 is as follows. The feedback control described above during lean burn operation is being performed. 256 cycles or more have elapsed since the start of the control in the preceding paragraph. By the way, in order to calculate the learning control correction coefficient Kc, the ECU
Numeral 20 measures the in-cylinder pressure at two points, that is, two points in the compression stroke and one point in the expansion stroke, based on signals from the in-cylinder pressure sensor 17 and the crank angle sensor 15 as sensors for detecting parameters representing the output state of the internal combustion engine. And use it as a parameter.

That is, as shown in FIG. 2, the ECU 20 has a function of an in-cylinder pressure detecting means 21 for measuring a total of three in-cylinder pressures of two points in a compression stroke and one point in an expansion stroke.
The in-cylinder pressure detecting means 21 detects the in-cylinder pressure P120B (i) (the first combustion chamber pressure) at 120 ° before the top dead center during the compression stroke of the internal combustion engine after the intake and exhaust valves are closed in the stroke i. The in-cylinder pressure P60B (i) (pressure in the second combustion chamber) during the compression stroke of the internal combustion engine at a timing later than the pressure P120B (i) but before the ignition timing (60 ° before top dead center). After the top dead center during the expansion stroke of the internal combustion engine at the time when the combustion is almost completed.
And the in-cylinder pressure at 60 ° (the third combustion chamber pressure). The three points of the compression stroke and the expansion stroke are a total of three points. The in-cylinder pressures P120B and P6 used in the calculating means 22 to calculate the combustion index Ci used for the feedback control described above.
The values at the measurement points 0B and P60A may be used.

The ECU 20 calculates the pressure information P in the combustion chamber.
Combustion index data calculation for calculating combustion index data Ci correlated to combustion fluctuation by the following equation (3) based on 120B (i), P60B (i) and in-cylinder pressure P60A (i) (third combustion chamber pressure). Means 101 are provided. Ci = (P60A (i) -P60B (i)) / (P60B (i) -P120B (i)) (1) That is, the combustion index Ci is the difference between P60A (i) and P60B (i). To the difference between P60B (i) and P120B (i).

Here, the denominator of this combustion index Ci (P60B
(i) -P120B (i)) has compression pressure information,
Since the information of the air amount (including the EGR amount) into the combustion chamber 1 is stored, the numerator (P60A (i) -P60B) of the combustion index Ci is obtained.
(i)) has the information of the engine output since it has the expansion pressure fluctuation information, and therefore has the combustion index Ci.
Will have information on the engine output per unit air volume.

The ECU 20 has an integrating means 102 for integrating the control data when the combustion index Ci exceeds the combustion deterioration determination threshold value Cth to the combustion deterioration side to obtain the combustion deterioration index Vc. The control data integrated by the integrating means 102 is constituted by the frequency at which the combustion index Ci exceeds the combustion deterioration determination threshold value Cth to the combustion deterioration side,
A combustion deterioration index Vc that reflects the amount of combustion fluctuation to be corrected in accordance with consideration from a stochastic viewpoint described later is calculated.

Here, the threshold value Cth for determining combustion deterioration is configured to be given by a map set by the volumetric efficiency ηv and the engine speed Ne. And the integrating means 1
The control data integrated in 02 is the excess amount (Cav-C) in which the combustion index Ci exceeds the average combustion index Cav to the combustion deterioration side.
i), and the combustion deterioration index V that reflects the amount of combustion fluctuation to be corrected in accordance with the probabilistic consideration described below.
c is calculated.

That is, the effect of the numerical value near the threshold value is reduced by integrating the weight of the deterioration of the combustion with weight. Here, the average combustion index Cav
Is configured to be set by one of the following two means. (1) An average of past data is obtained in advance and given as a constant. (2) In a real-time process, a moving average of about 100 cycles is obtained. (3) Determined by real-time processing using a primary filter having a large time constant.

Cav (i) = α · Cav (i−1) + (1−α) · Ci α = 0.95 (2) Then, these control data may be changed depending on the characteristics required by the control device. Or has been adopted. Further, the ECU 20 is provided with a judging means 104 for judging the quality of combustion based on the combustion deterioration index Vc within the set sampling period.

That is, the determination means 104 is configured to determine a combustion deterioration state by determining a correction coefficient Kc for the combustion deterioration index Vc accumulated in 256 cycles set in advance. Here, the correction coefficient Kc is determined as follows. [1] Vc> when _{Vc 0 + ΔVc, Kc (j} ) = Kc (j-1) + Kr · (Vc -Vc 0 -ΔVc) ··· (3-1) [2] Vc ₀ + ΔVc>Vc> Vc ₀ when -ΔVc, Kc (j) = Kc (j-1) ··· (3-2) [3] Vc <when _{Vc 0 -ΔVc, Kc (j)} = Kc (j-1) -Kl _{· (Vc -Vc 0 + ΔVc)} ··· (3-3) Note that, in order to limit the learning control correction coefficient Kc in the range of 0.15>Kc> -0.15, limiter means 202 is provided. Here, Kr is the enrichment coefficient and Kl is the leaning coefficient.

This is so configured that the control width by the learning control correction coefficient Kc as the second control coefficient is set wider than the control width of the fuel injection amount by the feedback control coefficient Kfb. Adjust the mutual weight. As a result, a required weight is given to the learning control correction coefficient Kc calculated for a relatively long time, and stable and reliable fuel injection control is performed. Timely fuel injection control is also ensured.

The parameter indicating the output state of the internal combustion engine can be constituted by data indicating the rotation state (for example, rotational acceleration) of a rotating shaft driven by combustion of the internal combustion engine. By the way, the above-mentioned combustion deterioration index Vc is:
From the viewpoint that the fluctuation of combustion is stochastic, it is set with the following significance.

That is, the combustion fluctuation is shown in FIG.
It can be assumed that it has the fluctuation characteristics as shown in the following, and the state of the fluctuation can be described by the following equations (4) and (5) based on random numbers generated with a probability according to the exponential distribution. Here, the horizontal axis in FIG. 15 indicates the ratio Kpt (ratio x) of the in-cylinder pressure Pi to the average effective pressure avPi of the engine, and the probability density Prb of the combustion fluctuation with respect to this indicates the possibility of the combustion fluctuation. I have.

Prb (x) = λ · exp (−λ · x) (4) Kpt = (1-x · Kprb) / {1-1 / (λ · Kprb)} ··· ( 5) This combustion fluctuation characteristic can be approximated by an exponential distribution with a parameter λ = 5, and this approximate characteristic is as shown in FIG. That is, the probability density P (x) of the combustion fluctuation is given by: P (x) = λ · exp (−λ · x) (6) On the other hand, Pi / avPi on the horizontal axis is the magnitude of the stochastic fluctuation. This is equivalent to normalizing the in-cylinder pressure by using the coefficient ε representing the degree, and is expressed by the following equation (7).

Pi / avPi = (1−ε · x) / (1−ε / x) (7) where a = λ / (λ−ε) and b = λ · ε / (λ −ε)
Then, Pi / avPi = ab × x (8) can be expressed. As shown by the characteristics in FIG. 16, the characteristics located to the right have a lower probability density and are in a situation where the combustion state deteriorates.

Here, the threshold value Pi / avPi = 0.9 for determining the deterioration of the combustion is assumed to be the case where the case where the right side of the boundary A in FIG. 16 is reached is judged as the case where the combustion deteriorates.
On the other hand, if the combustion fluctuation cov is expressed using probabilities, it is expressed as follows. First, the variance V of Pi / avPi (Pi / avPi
AVPI) is, V (Pi / avPi) = b 2 / λ 2 ···· (9) standard deviation of Pi / avPi σ (Pi / avPi ) is, σ (Pi / avPi) = {V (Pi / avPi )｝ ^1/2 = b / λ (10) Therefore, cov = σ (Pi / avPi) = b / λ = ε / (λ−ε) (11) Since it is known that there is a good correlation with the combustion index, Pi / avPi is replaced with Ci / avCi corresponding to the normalized combustion index. When the combustion deterioration index Vc is expressed using a probability, the combustion deterioration index Vc of the control data is expressed as Ci / avCi ≦ Cth /
avCi is the probability of being established.

Here, Cth / avCi is the threshold value of the combustion index, which is 0.9. When the threshold value of x is x ₀ , the combustion deterioration index Vc is the probability density P (x) of the combustion fluctuation.
The the integral up to the threshold value x ₀ 1 / ε. Here, 1 / ε is the value of x when Ci / avCi = ab × x = 0, and a = λ / (λ−ε), b = λ replaced earlier.
-It is obtained by substituting ε / (λ-ε).

Therefore, regarding the control data,

[0059]

(Equation 1)

Here, substituting x ₀ = (a−Cth / avCi) / b = {λ− (λ−ε) · Cth / avCi} / λ · ε, Vc becomes as follows. Vc = −exp (−λ / ε) + exp [｛(λ−ε) · Cth / av
Ci -λ｝ / ε] (12-2) FIG. 17 shows the combustion deterioration index Vc plotted by changing ε with respect to the combustion fluctuation COV.

That is, FIG. 17 shows the combustion fluctuation CO on the horizontal axis.
V, the mutual relationship is shown with the combustion deterioration index Vc as the vertical axis, and it can be said that there is a good linear relationship as shown in FIG. Therefore, there is a good correlation between the combustion deterioration index Vc and the combustion fluctuation COV. By adopting the combustion deterioration index Vc as a control element for the combustion fluctuation and performing feedback control, a stochastically stable and accurate result is obtained. Control is performed.

On the other hand, regarding the control data, the combustion deterioration index Vc is obtained by multiplying the probability of Ci <Cth by Cav-Ci, and is calculated as follows in consideration of this. Assuming that the average combustion index is normalized as Cav / avCi,

[0063]

(Equation 2)

Here, Cav / avCi = 1, Ci / avCi
= Abx, Vc is as follows:

[0065]

(Equation 3)

FIG. 18 shows the combustion deterioration index Vc plotted by changing ε with respect to the combustion fluctuation COV. That is, FIG.
The horizontal axis indicates the combustion fluctuation COV, and the vertical axis indicates the combustion deterioration index Vc. The vertical axis indicates the mutual relationship. As shown in the figure, it can be said that there is a good linear relationship.

Therefore, there is a good correlation between the combustion deterioration index Vc and the combustion fluctuation COV. By adopting the combustion deterioration index Vc as a control element for the combustion fluctuation and performing the feedback control, the probability is stochastically increased. Stable and accurate control is performed. Next, the fuel injection control centering on the calculation of the feedback correction coefficient Kfb will be described with reference to the flowcharts of FIGS.

First, in step A1 of FIG.
To three in-cylinder pressures P120 read as shown in FIG.
B, P60B and P60A are loaded. That is, the in-cylinder pressure P120B is read every crank interrupt 120 ° before top dead center (step B1 in FIG. 5), and the in-cylinder pressure P60B is read every crank interrupt 60 ° before top dead center (FIG. 6).
Step C1), the in-cylinder pressure P60A is 60 ° after the top dead center.
Is read at every crank interrupt (step D in FIG. 7).
1).

Thereafter, in step A2 of FIG. 4, a combustion index Ci is calculated based on the above equation (1), and
In step 3, the deviation ΔCi is determined. If the air-fuel ratio feedback allowable operation state is established, the YES route of step A4 is taken, and in step A5, the feedback correction coefficient Kfb is determined based on the accumulated information of the deviation ΔCi. and calculates the time T _B and other correction coefficients, fuel injection time seeking T _inj (step A7), the fuel injection time T
_The injector 6 is driven by _inj (step A).
8).

When the injector 6 is driven, adjustment with statistical learning control is performed in accordance with the flowcharts of FIGS. 9 and 10 as described later. In this case, when the combustion index Ci falls below a predetermined threshold value Cio, the difference is integrated, and the feedback correction coefficient Kfb is increased according to the integrated value to enrich the air-fuel ratio.
The engine can be operated in a state near the lean combustion limit. This greatly contributes to improvement of fuel efficiency and reduction of NOx.

The advantages of using the above-mentioned combustion index Ci are as follows. (1) Since the measurement points of the in-cylinder pressure are as small as three points, the amount of calculation for obtaining the combustion index Ci is small. (2) Equation (1) used to determine the combustion index Ci
Since the pressure difference is used for both the denominator and the numerator in Expression (2), the calculation for zero-point calibration of the in-cylinder pressure becomes unnecessary.

(3) Since the denominator and the numerator ratio are used to determine the combustion index Ci, the gain control of the in-cylinder pressure becomes unnecessary. (4) Since the combustion index Ci has engine output information per unit air amount, the combustion index Ci can be set to a substantially constant value regardless of the engine load. If the air-fuel ratio feedback is not permitted, the operation proceeds to step A4.
In step A6, the feedback correction coefficient Kfb is set to "1", and after that, the basic drive time T
Calculate _B and other correction coefficients to calculate the fuel injection time T _{inj
Is calculated} (step A7), and the injector 6 is driven during this fuel injection time T _inj (step A8).

Since the calculation of the fuel injection time T _inj is performed for each cylinder, the above-described fuel injection control is performed for each cylinder. As described above, in the present embodiment, a combustion index Ci defined using a small amount of detected in-cylinder pressure information is created,
Focusing on the fact that the combustion state of the engine can be easily evaluated using the combustion index Ci, the air-fuel ratio adjustment element as the engine combustion fluctuation adjustment element is controlled by using the above-described combustion state evaluation method. Since the combustion state of the engine can be controlled, lean combustion limit control can be easily achieved, which greatly contributes to improvement of fuel efficiency and reduction of NOx.

It is theoretically possible to perform rich combustion limit control by evaluating the rich combustion limit using the combustion index Ci. Also, instead of the accumulated information of the deviation ΔCi between the combustion index Ci and the set value Cio, the deviation ΔCi
It may be used to control the engine in a direction in which the magnitude of the deviation ΔCi decreases.

Further, in-cylinder pressure measurement points are 120 ° before top dead center, 60 ° before top dead center, 60 ° after top dead center, and the first in-cylinder pressure at two different points during the compression stroke of the engine. The three points of the pressure and the second in-cylinder pressure and the third in-cylinder pressure during the expansion stroke of the internal combustion engine may be measured, and the combustion index may be measured by using the third in-cylinder pressure and the first and second cylinder pressures. It may be defined by the ratio of the difference between the internal pressure to one of the cylinder pressures and the difference between the first and second cylinder pressures. Even using the combustion index defined in this way, it is possible to evaluate the combustion state of the engine and control the combustion state of the engine in the same manner as in the above case.

Further, based on the result of comparison between the combustion index and the threshold value, the EGR amount as the combustion fluctuation adjusting element may be controlled instead of or in addition to the air-fuel ratio as the combustion fluctuation adjusting element. . Next, the fuel injection control by statistical learning centering on the calculation of the combustion deterioration index Vc and the correction coefficient Kc will be described with reference to the flowchart of FIG.

First, in step S1, an interrupt synchronized with the engine stroke is executed, and the processes in and after step S2 are executed. In step S2, three measured in-cylinder pressures P120B (i), P60B (i), and P60A (i) are loaded. That is, the in-cylinder pressure P120B (i) is
Read at every 0 ° crank interrupt, cylinder pressure P60B
(i) is read every 60 ° crank interrupt before top dead center, and the in-cylinder pressure P60A (i) is read every 60 ° crank interrupt after top dead center.

Note that the reading of the in-cylinder pressure in this step is performed at P120 in the aforementioned feedback control.
B, P60B, and P60A may be configured to be performed. Next, in step S4, the calculation of the combustion index Ci by the combustion index data calculation means 101 is performed by the following equation. Ci = (P60A (i) -P60B (i)) / (P60B (i) -P120B (i)) (1) Further, in step S5, the combustion index Ci is smaller than the combustion deterioration determination threshold value Cth. If not, the return operation of step S6 is performed through the “NO” route, and the system is in a state of waiting for the next operation cycle.

On the other hand, when the combustion index Ci is smaller than the threshold value Cth for judging deterioration of combustion, the operation of step S7 is executed through the "YES" route because the combustion state is deteriorated. In step S7, the calculation of the combustion deterioration index Vc is performed by the integration of the integrating means 102. This calculation is performed for any of the control data which is employed in the apparatus.

First, when the control data is adopted, the following equation is calculated by adding a degree to the combustion deterioration index Vc calculated by the previous execution of step S7. Vc = Vc + 1 As a result, the frequencies at which the combustion index Ci exceeds the predetermined combustion deterioration determination threshold value Cth toward the combustion deterioration side are integrated.

When the control data is adopted, the combustion index C (i) is compared with the average combustion index C with respect to the combustion deterioration index Vc calculated by the previous execution of step S7.
The excess amount (Cav-Ci) exceeding from av to the combustion deterioration side is added. Vc = Vc + (Cav-Ci) Thus, the combustion deterioration amount is weighted and integrated, and the combustion deterioration index Vc in a state where the influence of the numerical value near the threshold value is reduced is calculated.

The combustion deterioration index Vc reflects the amount of combustion fluctuation to be corrected in accordance with the above-described probabilistic consideration, and is calculated in consideration of the combustion deterioration probability. Becomes Therefore, by correcting the fuel injection amount based on the combustion deterioration index Vc, the fuel injection control corresponding to the probability of combustion deterioration is stably performed.

Then, it is determined in step S8 whether the operation cycle has exceeded 256 cycles. If not, the return operation of step S9 is performed through the "NO" route to wait for the next operation cycle. Becomes If the operation cycle exceeds 256 cycles, the predetermined sampling period has elapsed, and the correction operation of step S10 and subsequent steps is executed through the “YES” route.

First, in step S10, the correction coefficient Kc (j) is set as follows. (1) Vc> When _{Vc 0 + ΔVc, Kc (j} ) = Kc (j-1) + Kr · (Vc -Vc 0 -ΔVc) (2) Vc 0 + ΔVc>Vc> when Vc ₀ -ΔVc, Kc ( j) = Kc (j-1 ) (3) Vc < when _{Vc 0 -ΔVc, Kc (j)} = Kc (j-1) -Kl · (Vc -Vc 0 + ΔVc) the set correction coefficient Kc The injection fuel is corrected according to (j) (step S11).

The fuel injection control is based on the fuel injection from the ECU 20.
Fuel injection time T of the injector 6 based on the injection control signal
_injIs controlled by controlling the fuel injection.
Time T _injIs calculated by the following equation. T_inj= Tb × K × (Kfb + Kc + 1) × Kafl ± Tac
c + Td Kc in this equation is the above-described correction coefficient Kc (j),
Fuel injection by Kc (j) set between 0.1 and 0.1
Time T_injIs adjusted to the desired state,
Your will be done.

That is, the fuel injection amount is corrected based on the combustion deterioration index Vc calculated corresponding to the combustion deterioration probability, and the fuel injection control corresponding to the combustion deterioration probability is stably performed. Note that the combustion deterioration index Vc is reset in step S12, and enters a state of waiting for the next calculation cycle.

As described above, in this embodiment, the combustion deterioration index Vc used for the fuel injection control has a good linear correlation with the combustion fluctuation of the internal combustion engine, and an accurate correction is performed in performing the learning control. Thus, accurate correction of the fuel injection amount is accurately performed. This makes it possible to stochastically cope with the deterioration of combustion without performing the correction conventionally performed by a single detection of deterioration of combustion, thereby preventing the occurrence of an air-fuel ratio limit cycle, Drivability, fuel efficiency,
The limit performance of the exhaust gas can be greatly improved.

Further, when statistically processing combustion fluctuations, a remarkably large amount of measurement data is generally required, and accurate control cannot be performed with the processing capacity of the engine ECU. Sufficient real-time control can be performed depending on the engine ECU capability. In addition, lean combustion limit control can be easily realized,
This greatly contributes to improvement of fuel efficiency and reduction of NOx.

The mutual relationship between the above-described calculation of the control coefficient Kfb for feedback control, the control coefficient Kc for learning control, and the fuel injection time Tinj will be described with reference to the flowcharts of FIGS. First,
In step SS1, the combustion index Ci is calculated. Then, in step SS2, the feedback determination switch means 27 makes a determination on the above-described lean feedback control determination condition.

If the feedback control condition is not satisfied in this determination, a "NO" route is taken, and steps SS3 to SS5 are executed, and step S3 is executed.
It reaches S23. From step SS3 to step SS5,
Timer, learning flag, feedback control correction coefficient Kfb
Is reset, and the feedback control correction coefficient K
In the state where fb is not updated, in step SS23, the fuel injection amount is set based on the correction coefficient Kfb as before.

On the other hand, if the lean feedback control condition is satisfied, a "YES" route is taken and step S
In S6, it is determined whether the learning control condition is satisfied. The determination is made based on the above-described determination conditions. If the determination is not satisfied, the learning start flag is reset in step SS24 through the “NO” route, and the feedback control step from step SS19 is performed.

If the learning control condition is satisfied, it is determined in step SS7 whether the learning start flag has been set. If the learning control flag has not been set for the first time in step SS7, the process proceeds to step SS7. SS8 to step SS10 are executed. In steps SS8 to SS10, the learning start flag is set, the combustion deterioration index Vc is reset to "0", and the variable N for counting the number of times of sampling is reset to "0".

After the reset operation is performed, in the next cycle, a "YES" route is taken from step SS7, and learning control in step SS11 and subsequent steps is performed. In step SS11, it is determined whether or not the combustion index Ci exceeds the combustion deterioration determination threshold value Cth to the combustion deterioration side. If it exceeds, the combustion has deteriorated, and in step SS12, the combustion deterioration index Vc An operation is performed.

Here, the calculation of the combustion deterioration index Vc is performed when the apparatus of the present embodiment employs the above-described control data.
The integration of the super excessive number is performed by the integration means 102. Vc (j) = Vc (j) +1 The calculation of the combustion deterioration index Vc is based on the average combustion index C when the apparatus of the present embodiment employs the above-described control data.
The accumulator 102 performs an operation of adding the difference between av and the combustion index Ci, that is, the amount of the combustion index Ci exceeding the average combustion index Cav, to the previous combustion deterioration index Vc. This corresponds to an operation of integrating the excess amount of the combustion index Ci with respect to the combustion deterioration index Vc.

Vc (j) = Vc (j) + (Cav-Ci (j)) In this case, in step SS25, Cav is set in advance.
Is calculated, and after this calculation, step SS12 is executed. By the way, if the "NO" route is taken in step SS11, since the combustion state is good, the calculation relating to the combustion deterioration index Vc is not performed, and step S11 is performed.
It reaches S13.

At step SS13, the counter N is set to "2".
56 "has been reached. This is for judging whether the calculation cycle of the combustion index Ci for the learning control has reached a predetermined number of times, and when the number of times reaches the predetermined number, steps SS15 and thereafter are executed. If the predetermined number of times has not been reached, the counter N is updated in step SS14 and the feedback control is performed in step SS14.
It reaches 19.

By the way, in step SS15,
The determining means 104 determines the learning control correction coefficient Kc from the combustion deterioration index Vc as follows. [1] Vc> when _{Vc 0 + ΔVc, Kc (j} ) = Kc (j-1) + Kr · (Vc -Vc 0 -ΔVc) [2] Vc ₀ + ΔVc>Vc> when Vc ₀ -ΔVc, Kc ( j) = Kc (j-1 ) [3] Vc <when _{Vc 0 -ΔVc, Kc (j)} = Kc (j-1) -Kl · (Vc -Vc 0 + ΔVc) Then, in step SS16, the limiter means 20
When the learning control correction coefficient Kc exceeds the range of 0.15>Kc> -0.15,
Rounded to upper or lower limit.

Then, in step SS17, the combustion deterioration index Vc is reset to "0", and in step SS18
, N = 1 is set, and the steps related to the learning control are ended. Thereafter, steps related to feedback control from step SS19 are executed, and first, a deviation ΔCi (j) of the combustion index Ci with respect to the reference combustion index Ci0 is calculated. Subsequently, a weighting process of the deviation ΔCi (j) is performed, and ΔAF (j) is calculated (steps SS19 and SS19).
20).

Then, in step SS21, the feedback control correction coefficient Kfb is calculated by the following equation. Kfb (j) = Kfb (j) + ΔAF (j) The calculated feedback control correction coefficient Kfb (j) is subjected to upper / lower limit clipping operation by the limiter means 26,
If it exceeds the predetermined range, it is rounded to the upper or lower limit (step SS22).

Thus, the setting of the feedback control control correction coefficient Kfb (j) is completed, and the fuel injection time Tinj is calculated in step SS23. At this time, the learning control correction coefficient Kc is set in step S
The value in S16 is adopted, and the calculated fuel injection time Tinj is a value in a state where both the correction for the learning control and the correction for the feedback control have been performed, and the fuel injection based on this value is performed.

As described above, since the correction for the learning control and the correction for the feedback control are performed with the required weights, good fuel injection control is stably performed. In addition, drivability by combustion limit control,
Limit operation of fuel consumption and exhaust gas is realized.

Further, since the statistical combustion fluctuation is learned, the operation at the limit air-fuel ratio becomes possible from the beginning of the lean operation.

[0103]

As described above, according to the control apparatus for an internal combustion engine of the present invention, the following effects and advantages can be obtained. (1) Statistical combustion fluctuations can be learned by the combustion fluctuation element control based on the statistically processed control data, and the engine can be operated at the limit air-fuel ratio from the beginning of the lean operation. (2) Drivability, fuel efficiency,
Limit operation of exhaust gas can be realized. (3) Learning control by statistical processing and feedback control in response to combustion fluctuation can be performed with required weights, and both reliable fuel injection control and quick reaction control can be performed. . (4) The fuel injection amount can be corrected based on the combustion deterioration index calculated according to the combustion deterioration, and the fuel injection control corresponding to the combustion deterioration can be performed stably. (5) By making the combustion deterioration index used in the fuel injection control have a good linear correlation with the combustion fluctuation of the internal combustion engine, it becomes possible to perform an accurate correction in performing the learning control, and to perform an accurate correction. The fuel injection amount can be corrected stably. (6) The learning control can be reliably performed by responding to the stochastic combustion deterioration without performing the correction by the single combustion deterioration detection, and the generation of the limit cycle of the air-fuel ratio A / F occurs. Can be prevented, and the drivability, fuel efficiency, and the limit performance of exhaust gas can be significantly improved in the lean burn engine. (7) In the case of statistically processing combustion fluctuations, a large number of measurement data are generally required, and accurate control cannot be performed with the processing capability of a computer for engine control. However, by introducing a combustion deterioration index, Control with sufficient real-time processing can be performed even with the conventional engine control computer capability. (8) Lean combustion limit control can be easily realized, which greatly contributes to improvement of fuel efficiency and reduction of NOx. (9) The calculation for the zero point calibration of the in-cylinder pressure becomes unnecessary, and the gain management of the in-cylinder pressure can be made unnecessary, whereby the combustion state of the engine can be easily evaluated.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing one embodiment of the present invention.

FIG. 2 is a control block diagram showing one embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an engine system equipped with the present device.

FIG. 4 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 7 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 8 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 9 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 10 is a flowchart illustrating a control procedure according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating pressure measurement points used for calculating a combustion index.

FIG. 12 is a diagram illustrating the relationship between combustion fluctuation near the lean limit and the crank angle.

FIG. 13 is a diagram illustrating a correlation between a combustion index near a lean limit and an engine output.

FIG. 14 is a diagram illustrating a relationship among a combustion index, an engine output, and an engine speed.

FIG. 15 is a diagram illustrating combustion fluctuation characteristics of an engine.

FIG. 16 is a diagram illustrating combustion fluctuation characteristics of an engine.

FIG. 17 is a diagram illustrating combustion fluctuation characteristics of an engine.

FIG. 18 is a diagram illustrating combustion fluctuation characteristics of an engine.

FIG. 19 is a diagram illustrating the relationship between the air-fuel ratio, combustion fluctuation, and NOx amount.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Intake passage 2a Surge tank 3 Exhaust passage 4 Intake valve 5 Exhaust valve 6 Injector 7 EGR passage 8 EGR valve 9 Air flow sensor 10 Intake air temperature sensor 11 Atmospheric pressure sensor 12 Throttle sensor 13 O ₂ sensor 14 Water temperature sensor 15 Crank angle Sensor 16 TDC sensor 17 In-cylinder pressure sensor 18 Spark plug 20 ECU 21 In-cylinder pressure detection means 22 Combustion index calculation means 23 Comparison means 24 Conversion means 25 Accumulation means 26 Limiter means 27 Feedback judgment switch means 27A Feedback judgment logic part 27B Switch part 101 Combustion Index data calculation means 102 Integration means 104 Judgment means 201 Learning control judgment switch means 201A Learning control judgment logic unit 201B Switch unit 202 Limiter means

Continuation of front page (56) References JP-A-2-153243 (JP, A) JP-A-3-37021 (JP, A) JP-A-3-50100 (JP, A) JP-A-61-96150 (JP) JP-A-5-231210 (JP, A) JP-A-63-174548 (JP, A) JP-A-2-49955 (JP, A) JP-A-3-202660 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 45/00 368 F02D 45/00 301 F02D 45/00 358 F02D 45/00 362 F02D 41/14 330

Claims (6)

(57) [Claims] 1. Parameter detection means for detecting a parameter representing an output state of an internal combustion engine; and combustion index data calculation means for calculating combustion index data correlated with combustion fluctuations based on the parameter value for each combustion of the internal combustion engine. First control information calculating means for comparing the combustion index data with a threshold value for determining combustion deterioration and calculating first control information for controlling a combustion fluctuation adjusting element of the internal combustion engine for each combustion. A second control information calculating means for statistically processing the combustion index data in the sampling period to calculate second control information for controlling the combustion fluctuation adjusting element; and a first control information and a second control information. And a control means for controlling the combustion variation element using the control information of (1). 2. The first control information and the second control information so that a control width of the combustion fluctuation element by the second control information is wider than a control width of the combustion fluctuation element by the first control information. The control device for an internal combustion engine according to claim 1, wherein a limit value is provided for each of the control information. 3. The first control information calculating means calculates that the first control information is calculated by detecting that the operating state of the internal combustion engine has reached a first operating state set in advance. When another situation is established in the first operating state, the second control information calculating means performs the second
2. The control device for an internal combustion engine according to claim 1, wherein the control information is calculated. 4. An integrating means for integrating control data when the combustion index data exceeds a combustion deterioration determination threshold value on the combustion deterioration side and obtaining the integrated data as a combustion deterioration index is provided to the second control information calculating means. The control device for an internal combustion engine according to claim 1, wherein the control device is provided. 5. The apparatus according to claim 1, wherein the parameter detecting means is configured to detect pressure information in the combustion chamber, and the pressure information in the combustion chamber at two different points in the compression stroke of the internal combustion engine is converted into the pressure information in the first combustion chamber and the pressure information in the second. When the pressure information of the combustion chamber is used as the pressure information of the combustion chamber and the pressure information of the combustion chamber in the expansion stroke of the internal combustion engine is used as the pressure information of the third combustion chamber, the combustion index data calculating means calculates the pressure information of the third combustion chamber and the first and second combustion chambers. The combustion index data is calculated by calculating the ratio of the difference between the pressure information in the chamber and the pressure information in one of the combustion chambers and the difference between the pressure information in the first and second chambers. The control device for an internal combustion engine according to claim 1, wherein 6. The control of an internal combustion engine according to claim 1, wherein said parameter detecting means is configured to detect data indicating a rotation state of a rotary shaft driven by combustion of the internal combustion engine. apparatus.