JP2903157B2 - Internal combustion engine combustion fluctuation reduction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine combustion fluctuation reducing device for reducing combustion fluctuation of an internal combustion engine (hereinafter, sometimes referred to as “engine”).

[Related Art] In general, combustion fluctuations in each cycle of an engine are factors that hinder engine performance, fuel efficiency, and driving feeling.

By the way, since the combustion fluctuation in each cycle is a physical phenomenon, it is considered that it is not independently random in each cycle but is affected by the past cycle in some form, but the mechanism is not clear. .

[Problems to be solved by the invention]

Therefore, it is difficult to predict the combustion fluctuation in each cycle as described above, and it is difficult to correct this by controlling the ignition timing and the air-fuel ratio to reduce the combustion fluctuation.

The present invention was devised in such a situation, and it is possible to reduce engine combustion fluctuations by predicting seemingly random cycle fluctuations using a statistical method and enabling correction in real time. It is an object of the present invention to provide an internal combustion engine combustion fluctuation reducing device.

[Means for solving the problem]

For this reason, the internal combustion engine combustion fluctuation reduction device of the present invention, in the internal combustion engine, in order to reduce the combustion fluctuation of the internal combustion engine,
Autocorrelation information calculating means for calculating autocorrelation information of information representative of the combustion state of a plurality of cycles in a certain cylinder of the internal combustion engine, and a magnitude of the value of the autocorrelation information obtained by the autocorrelation information calculating means Operating parameter correction means for setting a correction amount based on the operation parameter and correcting the operating parameter of the internal combustion engine.

[Action]

In the internal combustion engine combustion fluctuation reducing device of the present invention described above, the autocorrelation information calculating means calculates the autocorrelation information of the information representative of the combustion state of a certain cylinder of the internal combustion engine in the past plural cycles, and the operation parameter correction means Then, a correction amount is set based on the magnitude of the value of the autocorrelation information obtained by the autocorrelation information calculation means, and the operation parameters of the internal combustion engine are corrected.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an internal combustion engine combustion fluctuation reducing device as an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a control block diagram, FIG. 2 is an overall configuration diagram showing an engine system having the device, FIG. Is a flowchart for explaining the control procedure, FIG. 4 is a flowchart for explaining the procedure for calculating the maximum in-cylinder pressure, FIG. 5 is a view showing the ignition timing correction amount characteristic, and FIG. It is a table map figure.

The vehicle-mounted gasoline engine system controlled by the present apparatus is as shown in FIG. 2. In FIG. 2, the gasoline engine E (hereinafter simply referred to as engine E) is configured as an in-line four-cylinder engine. The engine E has an intake passage 1 and an exhaust passage 2 that communicate with the combustion chamber of each cylinder. The communication between the intake passage 1 and the combustion chamber is controlled by an intake valve, and the exhaust passage 2 and the combustion chamber communicate with each other. Are controlled by an exhaust valve.

In addition, an air cleaner is provided in the intake passage 1 in order from the upstream side.
3, a throttle valve 4 and an electromagnetic fuel injection valve (injector) 5 are provided, and an exhaust gas purifying catalytic converter (three-way catalyst) and a muffler (not shown) are arranged in the exhaust passage 2 in order from the upstream side. ) 6 are provided.

Note that the injectors 5 are provided in the intake manifold portion by the number of cylinders. Now, since the engine E of the present embodiment is an in-line four-cylinder engine, four injectors 5 are provided. That is, it can be said that the engine is a so-called multipoint fuel injection (MPI) type engine.

The throttle valve 4 is connected to an accelerator pedal via a wire cable, so that the opening changes according to the amount of depression of the accelerator pedal.

Further, each cylinder is provided with a spark plug 7 toward its combustion chamber (in FIG. 2, the spark plug 7 should be drawn in the vicinity of the engine combustion chamber, but for convenience of space, the spark plug 7 is separately provided). Is drawn at the position of)
Each ignition plug 7 is connected to a distributor 8, which is connected to an ignition coil 9. And the ignition coil 9
A high voltage is generated on the secondary coil side of the ignition coil 9 by the off operation of the power transistor 10 connected to the primary coil side of the ignition coil 9, and one of the four spark plugs 7 connected to the distributor 8 generates a spark ( Ignition). The power transistor
The ignition coil 9 starts energization (charging) by the ON operation of 10.

With such a configuration, the air sucked through the air cleaner 3 according to the opening degree of the throttle valve 4 is mixed with the fuel from the injector 5 at the intake manifold portion so as to have an appropriate air-fuel ratio, and the ignition plug 7 is discharged in the combustion chamber. By igniting at the appropriate timing, it is burned,
After the engine torque is generated, the air-fuel mixture is discharged into the exhaust passage 2 as exhaust gas, and after purifying three harmful components of CO, HC, and NO _X in the exhaust gas by the catalytic converter, the mixture is silenced by the muffler 6. It is designed to be released to the atmosphere.

An airflow sensor 11, a crank position sensor 12, and an in-cylinder pressure sensor 13 are provided to control the ignition timing of the engine E.

Here, the air flow sensor 11 is a volume flow meter that is provided in an air cleaner provided portion of the intake passage 1 and detects the amount of intake air from Karman vortex information. The crank position sensor 12 detects, for example, the 75 ° BTDC position of each cylinder. This allows the engine speed N to be detected. Therefore, since the crank position sensor 12 also functions as an engine speed sensor, the crank position sensor 12 may be hereinafter referred to as an engine speed sensor as needed.

The in-cylinder pressure sensor 13 is provided for each cylinder and detects the in-cylinder pressure of each cylinder.

Actually, since various controls such as fuel supply control are performed on the engine E in addition to the ignition timing control,
Although not shown, various sensors are provided. That is,
Intake air temperature sensor for detecting intake air temperature, atmospheric pressure sensor for detecting atmospheric pressure, potentiometer type throttle sensor for detecting opening of throttle valve 4, idle switch for detecting idling state, oxygen concentration in exhaust gas (O ₂
Oxygen concentration sensor (O ₂ sensor) for detecting the concentration of water, and a water temperature sensor for detecting the temperature of the engine cooling water.

And the detection signal from each of the above sensors is CPU, RAM,
The data is input to an electronic control unit (ECU) 14 including a ROM and necessary interface circuits.
Although not shown, a voltage signal from a battery sensor that detects the voltage of the battery and a signal from an ignition switch (key switch) are also input to the ECU 14.

Incidentally, an ignition timing control signal is output from the ECU 14 to the power transistor 10 via the ignition driver 15, and further, the four ignition plugs 7 are sequentially sparked from the ignition coil 9 via the distributor 8. .

As shown in FIG. 1, the ECU 14 includes an ignition advancing angle setting means 16, an autocorrelation information calculating means (hereinafter simply referred to as correlation information calculating means) 17, an ignition timing correction amount setting means 18, an ignition timing correction amount correcting means. 19. It has the function of the optimal ignition timing setting means 20.

Here, as shown in FIG. 6, the ignition advance setting means 16 determines the A / N (volume efficiency obtained by dividing the intake air amount A by the engine speed N) having the engine load information and the engine speed N Therefore, a two-dimensional map (memory) that determines the required ignition advance SAij (hereinafter, SAij is representative when there is no need to distinguish and describe SAij) is determined.

The correlation information calculation means 17 calculates normalized auto-correlation information RN (n) of the maximum in-cylinder pressure Pmax as information representing the combustion state of a certain cylinder of the engine in a plurality of past cycles.

Here, the method of calculating the normalized autocorrelation information RN (n) is as follows. First, an autocorrelation RXX0 (n) of a delay 0 cycle (hereinafter, simply referred to as “delay 0”) is obtained from the following equation.

RXX0 (n) = RXXOLD0 (n) × (1-K2) + DP (n) × DP (n) × K2 (1) Next, the autocorrelation RXX1 of one cycle of delay (hereinafter, simply referred to as “delay 1”). (N) is obtained from the following equation.

RXX1 (n) = RXXOLD1 (n) × (1-K3) + DPOLD (n) × DP (n) × K3 (2) Here, it should be noted that generally, the calculation of autocorrelation requires a huge amount of calculation. Therefore, it is difficult to apply to real-time control, but in the present embodiment, as described above, the algorithm is devised so that the autocorrelation can be obtained from the past two times of information. That is, the above equation (1),
As can be seen from (2), the autocorrelation we have been seeking
RXXOLD0 (n) and RXXOLD1 (n) (which are appropriately weighted) are newly added to the square information DP (n) × DP (n) and DPOLD (n) × DP of the maximum in-cylinder pressure deviation information. The autocorrelation is obtained by adding (n) (which is also weighted appropriately).

Finally, the autocorrelation RXX1 (n) with delay 1 is normalized by the autocorrelation RXX0 (n) with delay 0 RXX1 (n) / RXX0
By performing (n), normalized autocorrelation information RN (n) of the maximum in-cylinder pressure Pmax is obtained.

The above-mentioned n is a cylinder number, for example, assigned to the cylinders in the order of ignition. For example, the ignition order is set to the first, third, fourth, and second cylinders. In this case, the number of the first cylinder is 1 The number of the third cylinder is 2, the number of the fourth cylinder is 3, and the number of the second cylinder is 4.
Becomes

Further, DP (n) is the maximum in-cylinder pressure deviation for the cylinder numbered as described above, and this maximum in-cylinder pressure deviation DP
(N) is the deviation between the latest maximum in-cylinder pressure detected for the relevant cylinder and the average value of the maximum in-cylinder pressure up to the previous time, and DPOL
D (n) is the previous maximum in-cylinder pressure deviation.

 K2 and K3 are constants (<1).

The ignition timing correction amount setting means 18 has a memory or a calculation means for determining the ignition timing correction amount S from the maximum in-cylinder pressure deviation DP (n) as shown in FIG.

The ignition timing correction amount correction means 19 calculates the ignition timing correction amount S obtained by the ignition timing correction amount setting means 18 as correlation information calculating means.
An ignition timing correction amount DSA (n) corrected by the autocorrelation information RN (n) obtained in 17 is obtained.

The optimum ignition timing setting means 20 converts the required ignition advance SA obtained by the ignition advance setting means 16 into an ignition timing correction amount correcting means 19.
Is corrected by the ignition timing correction amount DSA (n) obtained in the step (1).

Therefore, the ignition timing correction amount correction means 19 and the optimum ignition timing setting means 20 set a correction amount based on the autocorrelation information RN (n) obtained by the correlation information calculation means 17 and set the correction amount as an operation parameter of the engine E. This constitutes operation parameter correction means for correcting the ignition timing SA.

Next, the control procedure for ignition will be described with reference to the flowcharts shown in FIGS. The routine shown in FIG. 3 operates every 180 ° of each cylinder TDC (top dead center), and the routine shown in FIG. 4 operates every 1 msec.

First, in step A1 of FIG. 3, PMAXOLD (n) = PMAX
(N), the cylinder of a certain number n (hereinafter, n
The previous maximum in-cylinder pressure Pmax of the cylinder) is stored. Here, the maximum in-cylinder pressure is measured as shown in FIG. That is, first, in step B1 in FIG. 4, the in-cylinder pressure is read from the in-cylinder pressure sensor 13, and this value is set as PCYL. Then, in step B2, if PCYL> PHI (PHI is the largest of the detected in-cylinder pressures), PHI is set to PCYL and the peak is held.

When the maximum in-cylinder pressure is obtained as described above, in step A2, PMAX (n) = PHI, and the current maximum in-cylinder pressure P is set.
Update max.

After that, the average value of the maximum in-cylinder pressure Pmax up to now PMAXAVEO
By performing the operation [see equation (3)] of adding the product obtained by multiplying LD (n) by the required weight and the product obtained by multiplying the current maximum in-cylinder pressure PMAX (n) by the required weight, the maximum is obtained. An average value PMAXAVE (n) of the in-cylinder pressure Pmax is obtained.

 PMAXAVE (n) = PMAXAVEOLD (n) × (1−K1) + PMAX (n) × K1 (3) where K1 is a constant smaller than 1.

Next, in step A4, the previous maximum in-cylinder pressure deviation
D (n), this is updated, and in step A5, P
MAX (n) -PMAXAVE (n) is the current maximum in-cylinder pressure deviation DP
This is updated in (n).

After that, in steps A6 and A7, each autocorrelation RX of delay 0 and 1
X0 (n) and RXX1 (n) are obtained from the above equations (1) and (2), and in step A8, a normalized autocorrelation RN (n) is obtained. Here, −1 ≦ RN (n) ≦ 1.

The processing of steps A1 to A8 is a correlation information calculating means.
Performed at 17.

In step A9, the ignition timing correction amount S determined by the maximum in-cylinder pressure deviation PD (n) is found from the table map shown in FIG. This processing is performed by the ignition timing correction amount setting means 18.

Then, in step A10, the ignition timing correction amount DSA (n) for the next cycle of the n cylinders corrected from the ignition timing correction amount S and the normalized autocorrelation RN (n) is obtained. The processing in these steps is performed by the ignition timing correction amount correction means 19.

Here, when the autocorrelation RN (n) is larger than 0, if the maximum in-cylinder pressure Pmax in a certain cycle is larger than the average, the next cycle is also larger than the average, and if the maximum in-cylinder pressure Pmax in a certain cycle is smaller than the average. There is also a relationship that the next cycle is smaller than the average, and when the autocorrelation RN (n) is 0,
There is no relation between the maximum in-cylinder pressure Pmax in a certain cycle and the maximum in-cylinder pressure Pmax in the next cycle. When the autocorrelation RN (n) is smaller than 0, the following equation is obtained when the maximum in-cylinder pressure Pmax in a certain cycle is larger than the average. Is smaller than the average, and if the maximum in-cylinder pressure Pmax in a certain cycle is smaller than the average, the next cycle is larger than the average. The absolute value of the autocorrelation RN (n) indicates the degree.

Therefore, the ignition timing correction amount DSA (n) is equal to the autocorrelation RN
When (n) is larger than 0, the value becomes a positive value, and the ignition timing correction amount DSA (n) becomes 0 when the autocorrelation RN (n) is 0.
And the ignition timing correction amount DSA (n) is the autocorrelation RN (n)
Is smaller than zero.

Thereafter, in step A11, if n ≧ 5, n = 1 is set under the condition that n = 1, and then the above-described ignition timing correction amount DSA is set to the cylinder number to be obtained, and then step A12 Then, the intake air amount A is read, and in step A13, the engine speed N is read.
Then, A / N is calculated from the intake air amount and the engine speed, and the ignition advance angle SA is found from the two-dimensional map shown in FIG. 6 based on the A / N and N. The processing in these steps is performed by the ignition advance setting means 16.

Then, in step A16, if n ≧ 5, nSA = nSA−
By setting nSA = n + 1 under the condition of 4, the cylinder number to be actually ignited next (if this number is assigned to the ignition order from 1 to 4 as described above, the cylinder of the next number is 2 Is the cylinder to be ignited next, so the above condition is satisfied), and in step A17, SA = SA + DSA (nSA)
[However, this DSA (nSA) is obtained in the previous two cycles], whereby the optimum ignition timing is obtained. This process is executed by the optimum ignition timing setting means 20.

Then, the optimum ignition timing information is set in the one-shot multivibrator of the ignition driver 15. Thus, at the timing of the optimal ignition timing, the power transistor 10 is turned off, and ignition is performed.

By correcting the ignition timing using a statistical method, that is, based on the value of the autocorrelation information for the maximum in-cylinder pressure, seemingly random cycle fluctuations can be predicted. Accordingly, it is possible to reduce combustion fluctuations of the engine.

Further, the correction of the ignition timing as an operation parameter including the change of the past combustion state is performed, and the combustion fluctuation can be reduced more reliably.

Further, in the present embodiment, as described above, the algorithm is devised so that the autocorrelation can be obtained based on the past two times of information, so that the ignition timing can be corrected in real time.

Although the maximum in-cylinder pressure Pmax information is used for obtaining the autocorrelation, a method of indirectly knowing the maximum in-cylinder pressure Pmax may be used. That is, the in-cylinder pressure change dP / dt information may be detected and used by using a light combustion sensor, or the engine speed fluctuation dN / dt information may be detected and used.

The ECU 14 also has a function of controlling the air-fuel ratio by controlling the amount of fuel injected from the injector 5. If the present invention is applied to the air-fuel ratio control, the ECU 14 may perform the third control.
In step A9 of the figure, instead of the ignition timing correction amount, the air-fuel ratio correction coefficient F (for example, the correction coefficient is such that DP (n) is 1.1 at the maximum on the plus side and 0.9 at the minimum on the minus side. Is set, and in step A10, the correction coefficient F is multiplied by the autocorrelation information RN (n) to obtain a corrected air-fuel ratio correction coefficient DFA.

Then, in step A15, to look up the base time T _B corresponding to A / N, N, Furthermore, in step A16, nSA = n
NFA = n + 3 instead of +1 (actually, n +
T = T _B × DFA (nFA) is assumed as the value four times ahead, that is, the cylinder that has just been calculated is selected.

In addition, the present invention does not use a distributor, but also provides a metering mechanism in a fuel passage to a carburetor in a low-voltage distribution type ignition device that distributes to a spark plug by switching operation of all semiconductor switching elements. Needless to say, the present invention can also be applied to a so-called electronic carburetor type in which the supplied fuel amount is controlled by this mechanism.

Further, it is needless to say that the present invention can be applied to ignition timing control of a multi-cylinder engine other than the four-cylinder engine.

〔The invention's effect〕

As described in detail above, according to the internal combustion engine combustion fluctuation reducing device of the present invention, an autocorrelation information calculation unit that calculates autocorrelation information of information representing the combustion state of a plurality of past cycles in a certain cylinder of the internal combustion engine is provided. A simple configuration in which there is provided an operation parameter correction means for setting a correction amount based on the value of the autocorrelation information obtained by the autocorrelation information calculation means and correcting the operation parameter of the internal combustion engine, There is an advantage that the seemingly random cycle fluctuation can be predicted and corrected in real time, thereby effectively reducing the engine combustion fluctuation.

Further, there is an advantage that the operation parameters including the past fluctuation of the combustion state are corrected, and the fluctuation of the combustion can be more reliably reduced.

[Brief description of the drawings]

1 to 6 show an internal combustion engine combustion fluctuation reducing device as one embodiment of the present invention, FIG. 1 is a control block diagram thereof, FIG. 2 is an overall configuration diagram showing an engine system having the present device, FIG. 3 is a flowchart for explaining the control procedure, FIG. 4 is a flowchart for explaining the procedure for calculating the maximum in-cylinder pressure, FIG. 5 is a diagram showing the ignition timing correction amount characteristic, and FIG. FIG. 8 is a table map diagram for storing a. DESCRIPTION OF SYMBOLS 1 ... Intake passage, 2 ... Exhaust passage, 3 ... Air cleaner, 4 ... Throttle valve, 5 ... Solenoid valve (injector), 6 ... Muffler, 7 ... Spark plug, 8 ... Distributor, 9 ... ... Ignition coil, 10 ... Power transistor, 11 ... Air flow sensor (volume flow meter), 12 ... Crank position sensor (engine speed sensor), 13 ... Cylinder pressure sensor, 14 ... Electronic control unit (ECU) , 15: ignition driver, 16: ignition advance setting means, 17: autocorrelation information calculation means, 18: ignition timing correction amount setting means, 19: ignition timing correction amount correction means, 20: optimal ignition Timing setting means, E ... Engine.

Claims (1)

(57) [Claims] An auto-correlation information calculating means for calculating auto-correlation information of information representing a combustion state of a certain cylinder of the internal combustion engine in a plurality of past cycles so as to reduce combustion fluctuations of the internal combustion engine; Operating parameter correction means for setting a correction amount based on the value of the autocorrelation information calculated by the autocorrelation information calculation means and correcting the operation parameters of the internal combustion engine. An internal combustion engine combustion fluctuation reduction device.