JPH08135487A - Knocking control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To simplify the computing processing of fuel increase quantity at the time of lag, and while to improve the fuel consumption at the same time. CONSTITUTION: Lag quantity per each air cylinder AKNK1 of all air cylinders are summed up so as to obtain the total lag quantity AKALL (step 41). This total lag quantity AKALL is compared with the lag increase quantity execution judgment value FRET (step 142), and in the case where AKALL>KFRET, Fknk is computed on the basis of a map of the engine speed Ne and the lag increase quantity Fknk (step 143). In the map to be used at this stage, lag increase quantity Fknk is set at 0 in the low engine speed side (for example, at 2000rpm or less), because the low engine speed side has a room of exhaust temperature in relation to the high engine speed side and the increase of lag is therefore unnecessary, and furthermore, it improves the emission. On the other hand, in the case of AKALL<=KFRET, the lag increase quantity Fknk is set at 0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking control device for an internal combustion engine, in which the ignition timing is corrected to the retard side when knocking occurs and the fuel injection amount is increased according to the retard amount. .

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine (engine) of an automobile, ignition timing is controlled on the basis of an engine speed and a load, which are parameters of an engine operating state. The ignition timing is advanced to the limit of the knocking limit, and when knocking starts to occur, the ignition timing is immediately retarded to quickly suppress the knocking. Furthermore, in today's engine control, in order to improve fuel efficiency and reduce emissions, an independent injection method in which fuel is independently injected from each injector is adopted for each cylinder of the engine, and with the improvement of knocking detection accuracy, Cylinder retard control for correcting the ignition timing to the retard side for each cylinder has been adopted. In this cylinder-by-cylinder retard control, the fuel injection amount is increased in accordance with the cylinder-by-cylinder retard amount, thereby suppressing a decrease in engine output during retard and reducing the exhaust temperature.

[0003]

By the way, in the retard control for each cylinder, the retard amount is calculated for each cylinder, so that the fuel injection amount can be controlled independently for each cylinder. However, in this case, it is necessary to calculate the increase value of the fuel injection amount from the retard amount for each cylinder, and the calculation process becomes complicated. Therefore, in order to simplify the calculation process, the present inventor is searching for a way to set the same increase value of the fuel injection amount of all cylinders. However, for example, if only a specific cylinder is retarded,
If the fuel injection amount of all cylinders is increased according to the retard angle amount,
The amount will be increased more than necessary, causing problems such as deterioration of fuel efficiency.

The present invention has been made in consideration of the above circumstances, and therefore an object thereof is to achieve both simplification of the calculation process of the fuel amount increase at the time of retardation and improvement of fuel consumption, and cost reduction. An object of the present invention is to provide a knocking control device for an internal combustion engine that can satisfy both the requirements for downtime and performance assurance.

[0005]

In order to achieve the above object, a knocking control device for an internal combustion engine according to claim 1 of the present invention includes knocking detection means for detecting knocking occurring in the internal combustion engine, and this knocking detection means. Knocking correction means for correcting and controlling the ignition timing to the retard side for each cylinder according to the detection signal of, and a retard angle increasing amount for increasing the fuel injection amount according to the ignition timing retard amount corrected by the knock correcting means. In the device including a correction means, the retard angle increase correction means calculates a total value or an average value of the cylinder-by-cylinder retard angle amounts, and obtains the fuel injection amount increase value according to the calculated value. .

Further, as in claim 2, the retard angle increase correction means multiplies the cylinder retard angle amount by a weighting factor when calculating the sum value or average value of the cylinder retard amount, and sums or You may make it average. Further, as in claim 3, the retard angle increase correction means may perform the smoothing process to calculate the total value or the average value of the cylinder-by-cylinder retard angle amounts.

In any of these cases, claim 4
As described above, the retard angle increase correction means may determine the fuel amount increase at the retard angle in consideration of the operating condition in addition to the total value or the average value of the cylinder-by-cylinder retard angle amounts.

[0008]

According to the structure of the first aspect, when knocking is detected by the knocking detecting means while the engine is operating, the knocking correcting means corrects and controls the ignition timing to the retard side for each cylinder. At this time, the retard angle increase correction means calculates a total value or an average value of the cylinder-by-cylinder retard angle amounts, and determines the fuel increase amount during the retard angle according to the calculated value. Therefore, for example, even when only the specific cylinder is retarded, the fuel amount at the time of retard is averaged for all the cylinders by obtaining the fuel increase amount at the time of retard by the total value or the average value of the retard amount for each cylinder. Increases can be determined and unnecessary fuel increases can be avoided.

By the way, depending on the type of engine, there is a case where the relationship between the retard amount for each cylinder and the fuel increase amount of each cylinder actually required varies among the cylinders. Therefore, in claim 2, when calculating the total value or average value of the cylinder-by-cylinder retard angle amounts, the cylinder-by-cylinder retard angle amount is multiplied by a weighting coefficient and summed or averaged to obtain the cylinder-by-cylinder retard angle amount. It is possible to reflect the relationship with the required fuel increase in each cylinder. As a result, it is possible to obtain the fuel amount increase at the time of retardation that is suitable for the engine model.

Further, according to a third aspect, the retardation amount increase correction means smoothes and calculates the total value or the average value of the cylinder-by-cylinder retardation amounts. This suppresses a change in the fuel amount increase at the time of a sudden retard and stabilizes the control.

Further, according to the present invention, the retard angle increase correction means determines the fuel amount increase at the retard angle in consideration of the operating condition in addition to the total value or the average value of the cylinder-by-cylinder retard angle amounts. As a result, it becomes possible to set the fuel amount increase at the time of retardation according to the operating conditions.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a 4-cylinder engine will be described below with reference to FIGS. First, the schematic configuration of the entire system will be described with reference to FIG. An air cleaner 23 is mounted on the upstream side of the intake pipe 22 of the engine 21, and the flow rate of intake air passing through the air cleaner 23 is detected by an air flow meter 24. Also,
A throttle valve 25 is provided in the middle of the intake pipe 22. An intake manifold 26 for introducing air into each cylinder of the engine 21 is connected to a downstream side of the intake pipe 22, and fuel is injected into each branch of the intake manifold 26 (see FIG. 2) for each cylinder. An injector 27 is attached.

An ignition plug 30 is attached to each cylinder of the engine 21, and the high voltage generated in the ignition coil 31 is passed through the distributor 32 to each ignition plug 30.
Are sequentially applied. The current of the primary coil of the ignition coil 31 is turned on / off by the power transistor 34 (see FIG. 2) of the igniter 33. The power transistor 34 is turned on and off when the engine control circuit 35 (EC
It is controlled by the ignition signal sent from U). Further, the distributor 32 is provided with a crank angle sensor 36 that outputs a signal corresponding to the crank angle.

On the other hand, near the center of the cylinder block of the engine 21, a knock sensor 37 is attached as knocking detecting means. This knock sensor 37
For example, the engine control circuit 3 outputs a signal corresponding to the knocking vibration level of the engine 21, which is formed of a piezoelectric element.
Output to 5 As shown in FIG. 2, the engine control circuit 35 has a built-in microcomputer including a CPU 38, a ROM 39, a RAM 40, an input / output interface 41, and the like, and includes an air flow meter 24, a crank angle sensor 36, a knock sensor 37, and the like. Simultaneous injection control of simultaneously injecting the injectors 27 of the respective cylinders is controlled based on the input signal, and the ignition signal is also controlled by controlling the on / off of the power transistor 34 of the igniter 33.

The ROM 39 of the engine control circuit 35 stores the programs of the routines shown in FIGS. 3 to 7, and the processing contents of the routines will be described below. The engine 21 of this embodiment is a 4-cylinder engine, and i is a cylinder number in each drawing.

In the fuel injection control routine shown in FIG. 3, first, at step 101, the basic injection amount Tp (injection time) is calculated by the following equation (1). Tp = K.Q / Ne (1) where K is a constant, Q is the intake air amount detected by the air flow meter 24, and Ne is the engine speed obtained from the output signal of the crank angle sensor 36.

After the calculation of the basic injection amount Tp, step 1
In 02, the final injection amount Tout is calculated by the following equation (2). Tout = Tp.alpha. + Fknk (2) Here, .alpha. Is various correction coefficients, and Fknk is the fuel increase amount at the time of retarding (hereinafter referred to as "retarding amount increase"). It is calculated.

After calculating the final injection amount Tout (injection time),
In step 103, the injectors 27 of the respective cylinders are simultaneously opened for a Tout period at a predetermined timing to inject fuel into the respective cylinders at the same time.

On the other hand, in the ignition timing control routine shown in FIG. 4, first, at step 111, the basic ignition timing ABSE is calculated from the two-dimensional map of the engine speed Ne and the intake air amount Q.
To calculate. Next, at step 112, the final ignition timing AOP is calculated by the following equation (3).

AOP = ABSE · β−AKNK _i (3) Here, β is various correction coefficients, and AKNK _i is the cylinder retarding amount, which is calculated by the knocking correction value setting routine of FIG. 5 described later. . From this equation (3), the final ignition timing AOP is corrected to the retard side at the time of knocking. After calculating the final ignition timing AOP, step 113
Then, the ignition coil 31 is energized and ignited at a timing corresponding to the final ignition timing AOP.

The knocking correction value setting routine shown in FIG. 5 is executed, for example, after the knocking determination section. In this routine, first, at step 121, the presence or absence of knocking is determined based on the output signal of the knock sensor 37. If there is no knocking, knocking correction is not necessary, so this routine is ended without doing anything. .

On the other hand, if it is determined that there is knocking, the routine proceeds to step 122, where the knocking correction amount AKRTD (for example, 0.5 ° C. A) is added to the cylinder retardation amount AKNK _i to obtain the cylinder retardation amount. AKNK _i is corrected and this routine ends. The above-described routines of FIGS. 4 and 5 serve as the “knocking correction means” in the claims.

On the other hand, the advance angle correction routine shown in FIG. 6 is interrupted, for example, every one second. In this routine,
The cylinder retard angle amount AKNK _i is subtracted from the cylinder retard angle amount AKNK _i to obtain the cylinder retard angle amount AKNK.
_i is corrected (step 131), and this routine ends.

The retard angle increase setting routine shown in FIG. 7 is a routine for setting the fuel amount increase Fknk at the time of retard, and functions as the "retard angle increase correction means" in the claims. In this routine, first in step 141, the cylinder-by-cylinder retardation amounts AKNK _i of all the cylinders are summed to obtain a total retardation amount AKAL.
Find L. Next, at step 142, this total retard angle amount AKALL is compared with the retard angle increase execution determination value KFRET,
If AKALL> KFRET, the routine proceeds to step 143, Fknk is calculated from the map of the engine speed Ne and the retardation increase Fknk, and this routine ends.

An example of the map used in this step 143 is shown in FIG. In the example of FIG. 8, the retard angle increase Fknk is set to 0 on the low rotation side (for example, 2000 rpm or less), and the retard angle increase Fknk is increased in accordance with the engine speed Ne in the rotation region higher than that. It is set.
The reason for this is that the low rotation side has a relatively large exhaust temperature on the low rotation side as compared to the high rotation side, and it is not necessary to increase the retard angle, and the emission is also improved by doing this. is there. On the other hand, in step 142 described above, AK
If it is determined that ALL ≦ KFRET, the retard angle increase Fknk
Is set to 0 and this routine ends.

According to the first embodiment described above, the cylinder-by-cylinder retard angle amounts AKNK _i of all the cylinders are summed to obtain the total retard angle amount AKAL.
Since L is calculated and the total retard angle amount AKALL is compared with the retard angle increase execution determination value KFRET to calculate the retard angle increase Fknk, for example, even when only a specific cylinder is retarded, all cylinders are retarded. It is possible to obtain the average retardation increase Fknk, and avoid unnecessary fuel increase,
It is possible to meet demands for improving fuel efficiency and reducing emissions. Moreover, since it is not necessary to calculate the retard angle increase for each cylinder, the calculation process of the retard angle increase can be simplified and the demand for cost reduction can be satisfied.

Moreover, in addition to the total value AKALL of the retardation amount AKNK _i for each cylinder, the retardation amount is calculated in consideration of the operating condition (in the first embodiment, the engine speed Ne). It is possible to set the retard angle increase according to the above, and it is possible to further enhance the effects of improving fuel efficiency and reducing emissions.

In this case, instead of the total retard amount AKALL (the total value of the retard amount AKNK _i for each cylinder), the retard amount AKN for each cylinder is changed.
Even if the retard angle increase Fknk is obtained by the average value of K _i (that is, the total retard angle amount AKALL / the number of cylinders), it is substantially the same. That is, when using the average value of the cylinder-specific retardation amounts AKNK _i , the process of step 141 is replaced with the process of calculating the average value of the cylinder-specific retardation amounts AKNK _i , and the process of step 142 is executed. It suffices to replace the processing of comparing the average value of the angle amount AKNK _i with the retard angle increase execution determination value KFRET / the number of cylinders.

On the other hand, FIG. 9 shows a second embodiment of the present invention.
The processing of steps 143 to 144 of the retard angle increase setting routine of FIG. 7 in the first embodiment is replaced with the processing of step 145. That is, in step 141, the cylinder-by-cylinder retardation amounts AKNK _i of all the cylinders are summed to obtain the total retardation amount AKAL.
After obtaining L, the routine proceeds to step 145, where the total retardation amount AKA
The retard increase Fknk is calculated from the two-dimensional map of LL and the engine speed Ne, and this routine ends.

In this second embodiment, step 14
If the two-dimensional map shown in FIG. 12 is used as the two-dimensional map used in 5, it is possible to set the retardation increase Fknk to a value similar to that in the first embodiment, which is exactly the same as in the first embodiment. The effect can be obtained. In the two-dimensional map shown in FIG. 12, the retard increase Fknk is set to 0 on the low rotation side (for example, 2000 rpm or less) for the same reason as in the first embodiment.

The retard angle increase Fknk does not necessarily have to be set to a value similar to that in the first embodiment, but may be set so that the retard angle increase Fknk is changed more finely than in the first embodiment, for example. Also in this second embodiment, the total retardation amount AKALL (the total value of the cylinder-by-cylinder retardation amount AKNK _i )
It goes without saying that the average value of the cylinder-by-cylinder retardation amount AKNK _i may be used instead of the above.

By the way, depending on the model of the engine 21, there is a case where the relationship between the cylinder-by-cylinder retard angle amount AKNK _i and the actually required retard angle increase amount of each cylinder varies among the cylinders.

FIG. 10 shows an embodiment in consideration of such a situation.
3 is a third embodiment of the present invention shown in FIG. In the third embodiment, in step 151 of the retard angle increase setting routine,
The cylinder-by-cylinder retardation amount AKNK _i is multiplied by each weighting coefficient a _i , and the total is obtained as the total retardation amount AKALL. Next, in step 152, as in the second embodiment, the retard angle increase Fk is calculated from the two-dimensional map of the total retard angle amount AKALL and the engine speed Ne (for example, the two-dimensional map shown in FIG. 12).
nk is calculated, and this routine ends.

In the third embodiment, the total retardation amount AK
When the ALL is obtained, the cylinder-by-cylinder retard angle amount AKNK _i is multiplied by the respective weighting factors a _i and summed to obtain the relationship between the cylinder-by-cylinder retard angle amount AKNK _i and the actually required retard angle increase amount of each cylinder Can be reflected, and the retard increase can be calculated according to the engine model.

Also in this third embodiment, instead of the total retard angle amount AKALL, the weighted average value of the individual cylinder retard angle amount AKNK _i (that is, the total retard angle amount AKALL / the number of cylinders) is used. It goes without saying that it is also good.

On the other hand, FIG. 11 shows a fourth embodiment of the present invention. In the fourth embodiment, in step 151 of the retard angle increase setting routine, the cylinder-by-cylinder retard angle amounts AKNKi of all cylinders are set.
Are summed to obtain the total retard angle amount AKALL _j of _j this time.
Incidentally, this will be the total amount of retardation AKALL _j, similarly to the step 151 of the third embodiment shown in FIG. 10, respectively multiplied by the weighting factor a _i to cylinder retard amount AKNK _i, the total of the sum current j Alternatively, the delay amount AKALL _j may be obtained.

After that, the routine proceeds to step 162, where the total retardation amount AKALL _j of this time _j is 1 / n by the following equation (4).
Smoothing is performed, and the value is set as a new total retardation amount AKALL _j . AKALL _j = (1−n) · AKALL _j−1 + n · AKALL _j (4) Here, AKALL _j−1 is the total retardation amount obtained in the previous (j−1) process. In this equation (4), for example, n =
It may be set to about 1/4.

After the total retardation amount AKALL _j is smoothed in this way, the routine proceeds to step 163, where the total retardation amount AKALL _j and the engine speed Ne are set as in the second and third embodiments. The retard angle increase Fknk is calculated from the two-dimensional map (for example, the two-dimensional map shown in FIG. 12) and the present routine ends.

In the fourth embodiment, the total retardation amount AK
Since ALL _j is subjected to the smoothing process, it is possible to suppress a rapid change in the retardation increase Fknk and stabilize the control.

Also in this fourth embodiment, instead of the total retard angle amount AKALL _j , the average value of the cylinder-by-cylinder retard angle amount AKNK _i (that is, the total retard angle amount AKALL _j / the number of cylinders) is used. It goes without saying that it is also good.

In each of the embodiments described above, the total retardation amount AK
In addition to ALL, the engine speed Ne is taken into consideration as an operating condition to calculate the retard increase Fknk, but instead of (or in addition to) the engine speed Ne, the engine load (intake air amount, intake air The retardation amount Fknk may be calculated in consideration of any of operating conditions such as pipe pressure), engine cooling water temperature, and throttle opening.

Further, each of the above-mentioned embodiments is an embodiment in which the present invention is applied to a four-cylinder engine, but it may be applied to an engine having five or more cylinders, and not only simultaneous injection but also group injection and independent injection. It is needless to say that the present invention can be variously modified and implemented without departing from the scope of the invention, such as being applicable to injection.

[0043]

As is apparent from the above description, according to the configuration of claim 1 of the present invention, the total value or the average value of the retard amount for each cylinder is calculated, and at the time of retard angle according to the calculated value. Since the fuel increase amount is calculated for each cylinder, even if only a specific cylinder is retarded, the average fuel increase amount for all cylinders can be calculated and unnecessary fuel increase is avoided. Therefore, it is possible to meet the demands for improving fuel efficiency and reducing emissions. Moreover, since it is not necessary to calculate the retard angle increase for each cylinder, the calculation process of the retard angle increase can be simplified and the demand for cost reduction can be satisfied.

In the second aspect, when calculating the sum or average of the cylinder retarding amounts, the cylinder retarding amounts are multiplied by the weighting factors and summed or averaged. It is possible to reflect the relationship between the angle amount and the retard amount increase of each cylinder that is actually required, and it is possible to obtain the retard amount increase according to the engine model.

Further, according to the third aspect of the invention, since the total value or the average value of the retard amount for each cylinder is smoothed and calculated, it is possible to suppress the change in the fuel increase amount at the time of the rapid retard angle. , The control can be stabilized.

Further, in the present invention, in addition to the total value or the average value of the retard amount for each cylinder, the fuel amount at the time of retard is calculated in consideration of the operating condition. The angle increase can be set, and the effects of improving fuel efficiency and reducing emissions can be further enhanced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire system showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a control system.

FIG. 3 is a flowchart showing a flow of processing of a fuel injection control routine.

FIG. 4 is a flowchart showing a processing flow of an ignition timing control routine.

FIG. 5 is a flowchart showing a processing flow of a knocking correction value setting routine.

FIG. 6 is a flowchart showing a processing flow of an advance angle correction routine.

FIG. 7 is a flowchart showing a processing flow of a retard angle increase setting routine.

FIG. 8 is a diagram showing an example of a map used in a retard angle increase setting routine.

FIG. 9 is a flowchart showing a processing flow of a retard angle increase setting routine in the second embodiment of the present invention.

FIG. 10 is a flowchart showing a processing flow of a retard angle increase setting routine in the third embodiment of the present invention.

FIG. 11 is a flowchart showing a processing flow of a retard angle increase setting routine in the fourth embodiment of the present invention.

FIG. 12 is a diagram showing an example of a map used in a retard increase setting routine of each of second to fourth embodiments.

[Explanation of symbols]

21 ... Engine, 24 ... Air flow meter, 33 ... Igniter, 35 ... Engine control circuit (knocking correction means, retard angle increase correction means), 37 ... Knock sensor (knocking detection means).

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area F02P 5/152 5/153

Claims (4)

[Claims] 1. A knocking detection means for detecting knocking occurring in an internal combustion engine, a knocking correction means for correcting and controlling ignition timing to a retard side for each cylinder in accordance with a detection signal of the knocking detection means, and this knocking correction. In a knocking control device for an internal combustion engine, comprising: a retard angle increase correction unit that increases a fuel injection amount according to a retard angle amount of ignition timing corrected by the means, the retard angle increase correction unit is a cylinder retard angle amount. A knocking control device for an internal combustion engine, which calculates a total value or an average value of, and obtains the fuel increase amount at the time of retardation according to the calculated value. 2. The retard angle increase correction means, when calculating the sum or average of the cylinder retard amounts, sums or averages by multiplying the cylinder retard amounts by a weighting coefficient. The knocking control device for an internal combustion engine according to claim 1. 3. The knocking control of the internal combustion engine according to claim 1, wherein the retard angle increase correction means smoothes and calculates a total value or an average value of the cylinder-by-cylinder retard angle amounts. apparatus. 4. The retardation amount increase correction means determines the fuel amount increase during retardation in consideration of operating conditions in addition to the total value or the average value of the cylinder-by-cylinder retardation amount. The knocking control device for an internal combustion engine according to any one of 1 to 3.