JP2010133281A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition timing control device for an internal combustion engine, avoiding such a fact that occurrence of knocking is not effectively suppressed due to the lower limit guard of a learning value and engine output is reduced, in an area having a large variation in an effect on occurrence of knocking caused by the secular change of the internal combustion engine within a basic leaning area. <P>SOLUTION: A plurality of multipoint learning areas is set in the area having the large variation in the effect on the occurrence of knocking caused by the secular change of the engine 1 within the basic learning area, and each multipoint learning value used for correcting ignition timing for suppressing occurrence of knocking is prepared with respect to each multipoint learning area. The multipoint learning value is updated based on a feedback term increased or decreased according to the presence or absence of occurrence of knocking. The lower guard value of the multipoint learning value is set to a value different with respect to each multipoint learning area according to the degree of the effect on the occurrence of knocking caused by the secular change of the engine 1 with respect to each multipoint learning area, and is set to the optimum value according to the degree of the effect. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

In an internal combustion engine such as an automobile engine, ignition timing control is performed including the retardation of the ignition timing for suppressing the occurrence of knocking.
Such ignition timing control of the internal combustion engine is performed using an ignition timing command value calculated based on the engine operating state, etc., and the ignition timing of the engine is retarded as the ignition timing command value decreases through the control. It becomes. The ignition timing command value is a basic learning value that is corrected based on a feedback term that increases or decreases depending on the presence or absence of knocking with respect to the knock limit ignition timing calculated based on the engine operating state, and that is updated based on the feedback term. It is calculated by adding correction according to.

  The feedback term used for calculation of the ignition timing command value is reduced by a predetermined retarded update amount when knocking occurs to correct the ignition timing, and when no knocking occurs, a predetermined advance is made. The ignition timing is increased by an angle update amount to advance the ignition timing. Therefore, the feedback term can immediately retard the ignition timing when knocking occurs to suppress knocking, and advance the ignition timing when knocking does not occur, thereby allowing the engine output reduced by the retardation of the ignition timing. This is a correction term to recover as much as possible.

  The basic learning value used for calculating the ignition timing command value is prepared for each of a plurality of basic learning areas divided according to the engine operating state and corresponds to the current engine operating state. It is updated based on. Such updating of the basic learning value is realized, for example, by using a value obtained by performing gradual change processing on the feedback term as a new basic learning value. The basic learning value updated in this way is a correction term for steadily correcting the ignition timing so as to suppress the occurrence of knock. As for the basic learning value, an upper limit guard and a lower limit guard are usually applied after the update in order to avoid an excessively large value or an excessively small value during the update (see Patent Document 1).

  Incidentally, when the internal combustion engine deteriorates over time, such as deposit deposits in the combustion chamber, knocking is likely to occur in the engine, and the basic learning value is updated to a value on the decrease side based on this. The basic learning value updated in this way is considered to be a value corresponding to the shift amount when the knock limit of the ignition timing shifts to the retard side due to the deterioration of the internal combustion engine. Therefore, by correcting the ignition timing (directly the knock limit ignition timing) using the updated basic learning value, it is possible to prevent the occurrence of knocking due to aging deterioration of the internal combustion engine. Become.

  However, the influence of knocking due to deterioration over time of an internal combustion engine may vary greatly depending on the engine operating region that is finer within the same basic learning region. In this case, when the ignition timing is corrected using the basic learning value set for each basic learning region, the basic learning value may be knocked due to deterioration over time of the internal combustion engine depending on the engine operating state in the basic learning region. It may become an inappropriate value in suppressing Specifically, in suppressing the occurrence of knocking, the basic learning value becomes too large to prevent the knocking from being effectively suppressed, or the basic learning value becomes too small and the ignition timing is excessive. There is a risk that the output of the internal combustion engine will be reduced by being corrected to the retard side.

  In order to deal with such problems, a plurality of subdivided areas in the basic learning area are divided into areas having a large variation in the influence on the occurrence of knock due to aging of the internal combustion engine, as shown in Patent Document 2. It is conceivable that a learning area is set and a subdivided learning value is prepared for each subdivided learning area. In this case, if the current engine operating state is within the basic learning region where there is a large variation in the influence on knock occurrence due to aging of the internal combustion engine, the current engine operating state exists in the subdivided learning region. The subdivided learning value of the region to be updated is updated based on the feedback correction term, and the updated subdivided learning value is used for correcting the ignition timing instead of the basic learning value.

Therefore, even in a region where the variation in the influence of knock generation due to aging of the internal combustion engine within the basic learning region is large, the occurrence of knocking is suppressed for each subdivided learning value for each learning region that is subdivided according to the variation. It can be set to an appropriate value. Then, by correcting the ignition timing using the respective subdivided learning values in the subdivided learning region, it becomes impossible to effectively suppress the occurrence of knock in the internal combustion engine in the same region, or It is possible to suppress the occurrence of a problem that the output is reduced due to excessive correction to the retard side.
JP-A-2005-147112 (paragraph [0045]) JP 62-45958 (page 6, upper left column, line 13 to upper right column, line 4)

  As described above, by correcting the ignition timing using the subdivided learning value, even in a region where there is a large variation in the influence on the occurrence of knock due to aging of the internal combustion engine in the basic learning region, the ignition timing is determined according to the variation. It is possible to prevent the occurrence of knocking effectively and not to be an excessively retarded value.

  However, if the lower limit guard is used for each sub-learning value using the lower limit guard value for the basic learning value, each sub-learned learning value is uniformly guarded by the lower limit guard value, and all of the sub-learned learning values are It is difficult to make the value small so that the occurrence of knocking at can be effectively suppressed, and to make the ignition timing not excessively retarded. That is, in the basic learning area where the variation in the influence of knocking due to the aging of the internal combustion engine is large, in any of the learning areas obtained by subdividing the same area, the ignition timing is corrected by the subdivided learning value. Even if it performs, either of the malfunctions shown in the following [1] and [2] is likely to occur. [1] The ignition timing cannot be retarded until the subdivided learning value is excessively guarded on the increase side (advance side) by the lower limit guard value and the occurrence of knocking in the internal combustion engine can be effectively suppressed. [2] In the lower limit guard of the subdivided learning value by the lower limit guard value, the lower limit guard is not performed until the subdivided learning value becomes an excessively decreasing (retarding) value, resulting in excessively retarding the ignition timing. The engine output decreases with the value on the side.

  The present invention has been made in view of such circumstances, and its purpose is to provide a lower limit guard for the learning value in a region where there is a large variation in the influence on the occurrence of knock due to aging of the internal combustion engine in the basic learning region. An object of the present invention is to provide an ignition timing control device for an internal combustion engine that can prevent the occurrence of knocking effectively and prevent the engine output from decreasing.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, there is provided an ignition timing control device for controlling the ignition timing of an internal combustion engine to be retarded as the command value decreases based on the ignition timing command value. The timing command value is corrected by a feedback term that increases or decreases depending on whether knocking occurs or not, and is corrected by a basic learning value that is updated based on the feedback term, with respect to the knock limit ignition timing calculated based on the engine operating state The basic learning value is prepared for each of a plurality of basic learning regions divided according to the engine operating state, and the value of the basic learning region corresponding to the current engine operating state is calculated. Is updated based on the feedback term, and the value to which the lower limit guard is applied after the update is the ignition timing of the internal combustion engine used for correcting the knock limit ignition timing. In the control device, a plurality of regions that are within at least one of the plurality of basic learning regions and in which the influence on the occurrence of knock due to deterioration over time of the internal combustion engine varies are determined according to engine operating conditions. Multi-point learning areas are set, and multi-point learning values used for correcting the knock limit ignition timing are prepared for each of the multi-point learning areas. When in the multi-point learning area, the value of the multi-point learning area is updated based on the feedback term, and after the update, a lower limit guard based on the lower limit guard value is applied and used to correct the knock limit ignition timing. Yes, with respect to the lower limit guard value of the multipoint learning value, according to the degree of influence on the occurrence of knock due to aging of the internal combustion engine in each of the plurality of multipoint learning regions, It was summarized as being set to different values to multipoint learning each region.

  According to the above configuration, a plurality of multi-point learning areas are set in an area where the influence on knock occurrence due to aging deterioration of the internal combustion engine in the basic learning area is large, and the current engine operation among these multi-point learning areas is set. Correction by the multipoint learning value corresponding to the multipoint learning region having the state is added to the knock limit ignition timing. By correcting the knock limit ignition timing using the multipoint learning value, it is possible to suppress the steady occurrence of knock in the engine due to aging deterioration of the internal combustion engine or the like. In addition, the lower limit guard value for guarding the lower limit of the multipoint learning value is different for each multipoint learning area depending on the degree of the influence on the occurrence of knock due to aging deterioration of the internal combustion engine in each multipoint learning area. Since it is set, it is possible to set an optimum value according to the degree of the influence. The multipoint learning value that is guarded based on such a lower guard value is used to suppress the occurrence of knock according to the variation in the region where the influence on the occurrence of knock due to aging of the internal combustion engine is large in the basic learning region. Is an appropriate value. In other words, the lower limit guard based on the lower limit guard value is a value that is so large that the occurrence of knock in the internal combustion engine cannot be effectively suppressed, or the ignition timing is excessively retarded and the engine output is reduced. It does not become so small that it decreases. Therefore, in the basic learning region, the occurrence of knocks is effectively reduced due to the lower limit guard of the multi-point learning value in the region where the variation in the influence on the occurrence of knock due to aging of the internal combustion engine is large, that is, in each multi-point learning region. It becomes possible to avoid that the engine output cannot be suppressed and the engine output decreases.

  According to a second aspect of the present invention, in the first aspect of the invention, the plurality of basic learning regions are partitioned according to an engine speed, and the multi-point learning region is defined by the plurality of basic learning regions. Of these, the engine rotation speed change direction is set to the engine low load side area in the basic learning area on the lowest rotation side, and is divided according to the engine rotation speed and engine load, and the number of engine load directions is The gist is that the number is larger than the number of rotation directions.

  Regarding the region where the variation in the influence on knock occurrence due to aging of the internal combustion engine in the basic learning region is large, the change in the engine rotation speed among the plurality of basic learning regions It occurs on the engine low load side. And in the region where the variation in the influence on the occurrence of knock due to deterioration over time of the internal combustion engine is large, the variation tends to be larger in the direction of change of the engine load than in the direction of change of the engine speed and to be wide. There is. According to the above configuration, based on such a tendency, a plurality of multipoint learning areas are set in the low load side area in the basic learning area on the lowest rotation side, and the engine speed in the multipoint learning area is set. The number for the direction of change of the engine is greater than the number for the direction of change of the engine load. For this reason, even if the above-mentioned variation becomes large in the change direction of the engine load in the region on the low engine load side and reaches a wide range, it is possible to cope with such a large variation.

  According to a third aspect of the invention, in the first or second aspect of the invention, the plurality of basic learning regions are partitioned according to an engine speed, and the multipoint learning region is the plurality of basic learning regions. The engine rotation speed change direction is set in the engine low load side area within the basic learning area on the lowest rotation side, and is divided according to the engine rotation speed and the engine load. The lower limit guard value is set to a smaller value in the multi-point learning region on the low rotation side in the direction of change in the engine speed, and the lower limit guard value is set to the minimum value in the direction of change in the engine load. The gist is that a multipoint learning region that is close to the same region is set to a smaller value.

  Regarding the region where the variation in the influence on knock occurrence due to aging of the internal combustion engine in the basic learning region is large, the change in the engine rotation speed among the plurality of basic learning regions It occurs on the engine low load side. And regarding the influence on the occurrence of knock due to aging of the internal combustion engine, among the multi-point learning areas, the change direction of the engine rotation speed becomes larger in the multi-point learning area on the low rotation side, and the change direction of the engine load There is a multi-point learning region where the above influence is maximum, and the multi-point learning region closer to the same region becomes smaller. According to the above configuration, the multipoint learning value in each multipoint learning region corresponds to the fact that the degree of influence on the occurrence of knock due to aging of the internal combustion engine differs for each of the plurality of multipoint learning regions as described above. The lower limit guard value used for the lower limit guard is set. Therefore, for each multipoint learning value that is guarded by the lower guard value, ignition is performed so that knocking can be effectively suppressed according to variations in the influence on knocking caused by aging of the internal combustion engine. While retarding the timing, the ignition timing is excessively retarded so that the engine output does not decrease.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, when the current engine operating state is in a multipoint learning region, the multipoint learning region with respect to the knock limit ignition timing. In addition to the correction by the basic learning value of the basic learning area in which the engine is present, the correction by the multi-point learning value of the multi-point learning area is added. When sticking of the learning value to the lower limit guard value occurs, weight reduction processing is performed to reduce the basic learning value of the basic learning area where the multipoint learning area exists, and the multipoint learning value is stuck to the lower limit guard value When the problem is solved, the gist is to stop the weight reduction for the basic learning value by the weight reduction processing.

  In the multi-point learning area with the current engine operating state, when the multi-point learning value is stuck to the lower limit guard value to reduce the multi-point learning value in order to suppress the occurrence of knocking, the multi-point learning There is a possibility that the basic learning value of the basic learning area where the area exists has a margin with respect to the lower limit guard. According to the above configuration, when the basic learning value is reduced through execution of the weight reduction process in such a situation, the basic learning value is decreased until the lower limit guard is performed, thereby retarding the ignition timing. Therefore, the occurrence of knocking can be suppressed. Therefore, in order to suppress the occurrence of knocking in the internal combustion engine, it is possible to effectively use the margin of the basic learning value with respect to the lower limit guard. In addition, when the sticking of the multipoint learning value to the lower limit guard value is resolved, the basic learning value reduction by the execution of the weight reduction process is stopped, and the basic learning value is returned to the state before the weight reduction. The ignition timing is not retarded more than necessary based on the learning value reduction.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, when the current engine operating state is in a multipoint learning region, the basic learning region in which the multipoint learning region exists with respect to the knock limit ignition timing. The amount of change when the basic learning value is changed in the basic learning region where the multipoint learning region exists, in addition to correction by the learning value and correction by the multipoint learning value of the multipoint learning region. It is possible to execute a reflection process that changes the multipoint learning value of each multipoint learning area in the direction opposite to the direction of change of the basic learning value, and the feedback term is added to the feedback term in the basic learning area where the multipoint learning area exists. When the basic learning value changes based on the basic learning value update, the reflection processing is executed, and the multi-point learning value in the multi-point learning area is stuck to the lower limit guard value. When basic learned value of the basic learning ranges in the presence of the multipoint learning ranges through execution of the reduction process brute changes was summarized in that prohibits execution of the reflection process.

  When the current engine operating state is in a basic learning region where a multi-point learning region exists and is in a region other than the multi-point learning region, the basic learning value of the basic learning region is updated and changed based on the feedback term. When the basic learning value changes in this way, when the engine operating state shifts to the multi-point learning region in the basic learning region, the ignition timing after the transition is affected by the change in the basic learning value, thereby There is a possibility that the timing becomes an inappropriate value for suppressing the occurrence of knocking, or that the timing is too retarded to cause a decrease in engine output.

  However, according to the above configuration, when a change in the basic learning value occurs, the multi-point learning value is changed in the direction of change in the basic learning value by the amount of change when the basic learning value changes through execution of reflection control. Is changed in the opposite direction. For this reason, even if a change in the basic learning value occurs, there is no effect on the ignition timing due to the change in the multipoint learning region. There is no problem that the value becomes an appropriate value or the value is too retarded to cause a decrease in engine output.

  However, when the basic learning value is changed to the reduction side through the execution of the weight reduction process, if the reflection processing is executed and the multipoint learning value is changed to the increase side, the multipoint learning value becomes an aging deterioration of the internal combustion engine, etc. This value is inappropriate as a value for suppressing the occurrence of steady knocking in the same engine. Considering this, in the above configuration, when the basic learning value changes through the execution of the weight reduction process, the execution of the reflection process is prohibited. Thereby, it is avoided that the multipoint learning value becomes the above-described inappropriate value, and accordingly, the occurrence of steady knocking in the engine due to the deterioration of the internal combustion engine in the multipoint learning region cannot be suppressed. .

Hereinafter, an embodiment in which the present invention is embodied in an ignition timing control device for an automobile engine will be described with reference to FIGS.
In the engine 1 shown in FIG. 1, air is sucked into the combustion chamber 2 through the intake passage 3 and fuel injected from the fuel injection valve 4 is supplied to the combustion chamber 2. When the air / fuel mixture is ignited by the spark plug 5, the air / fuel mixture burns, the piston 6 reciprocates, and the crankshaft 7 that is the output shaft of the engine 1 rotates. The air-fuel mixture after combustion is sent out from each combustion chamber 2 to the exhaust passage 8 as exhaust gas.

  Such an ignition timing control device for the engine 1 includes an electronic control device 26 that executes various operation controls of the engine 1. This electronic control unit 26 includes a CPU that executes various arithmetic processes related to the above control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU calculation results, and the like. An input / output port for inputting / outputting signals is provided.

Various sensors shown below are connected to the input port of the electronic control unit 26.
An accelerator position sensor 28 that detects the amount of depression (accelerator depression amount) of the accelerator pedal 27 that is depressed by the driver of the automobile.

A throttle position sensor 30 that detects the opening (throttle opening) of the throttle valve 29 provided in the intake passage 3.
A knock sensor 31 that detects occurrence of knock in the engine 1.

An air flow meter 32 for detecting the amount of air taken into the combustion chamber 2 through the intake passage 3;
A crank position sensor 34 that outputs a signal corresponding to the rotation of the crankshaft 7 and is used for calculation of an engine speed (engine speed).

The output port of the electronic control device 26 is connected to a drive circuit for the spark plug 5 and the like.
The electronic control unit 26 grasps the engine operating state such as the engine rotation speed and the engine load (the amount of air taken into the combustion chamber 2 per cycle of the engine 1) based on the detection signals input from the various sensors. To do. The engine speed is obtained based on a detection signal from the crank position sensor 34. Further, the engine load is calculated from the intake air amount of the engine 1 and the engine rotation speed obtained based on detection signals from the accelerator position sensor 28, the throttle position sensor 30, the air flow meter 32, and the like. The electronic control unit 26 outputs command signals to various drive circuits connected to the output port in accordance with engine operating conditions such as engine load and engine speed. Thus, various operation controls such as ignition timing control of the engine 1 are performed through the electronic control unit 26.

Next, an outline of ignition timing control of the engine 1 will be described.
The ignition timing of the engine 1 is controlled to the retard side as the ignition timing command value ST decreases based on the ignition timing command value ST obtained from the engine operating state or the like. The ignition timing command value ST is corrected, for example, by adding a correction by a feedback term F that increases or decreases depending on the presence or absence of knocking to the knock limit ignition timing (BT-R) calculated based on the engine operating state. It is calculated by adding a correction by the basic learning value AG (i) updated based on the term F.

  Here, the knock limit ignition timing (BT-R) used for the calculation of the ignition timing command value ST is the most advanced ignition timing that does not cause knock under standard environmental conditions based on the engine load and the engine speed. Is calculated by subtracting a knock margin R, which is a fixed value determined in advance by experiments or the like, from the base ignition timing BT calculated as follows. The knock limit ignition timing (BT-R) calculated in this way is a value obtained by retarding the base ignition timing BT by the knock margin R, and it is the most difficult to cause knock under the environmental conditions where knocking is most likely to occur. This value represents the ignition timing on the advance side. The environmental conditions include air temperature, humidity, atmospheric pressure, engine cooling water temperature, and the like, and the likelihood of knocking in the engine 1 changes according to these conditions.

  The feedback term F used for the calculation of the ignition timing command value ST is reduced by a predetermined delay update amount a when it is determined that knocking has occurred based on the detection signal from the knock sensor 31, and the ignition timing is calculated. Is retarded, and when it is determined that knocking does not occur, the ignition timing is increased by a predetermined advance angle update amount b to correct the ignition timing. Therefore, the feedback term F immediately retards the ignition timing when knocking occurs to suppress knocking, and if there is no knocking, advances the ignition timing and reduces the engine output reduced by the retardation of the ignition timing. This is a correction term to recover as much as possible.

  The basic learning value AG (i) used for the calculation of the ignition timing command value ST is divided into a plurality (in this example, “3”) of basic learning areas i divided according to engine operating conditions such as engine load and engine speed. It is prepared for each (i = 1, 2, 3). As the basic learning value AG (i) used for calculation of the ignition timing command value ST, the value of the basic learning region i corresponding to the current engine operating state is used. Further, in the basic learning region i where the current engine operating state is present, the basic learning value AG (i) is updated based on the feedback term F. Such an update of the basic learning value AG (i) is realized, for example, by setting a value obtained by subjecting the feedback term F to the gradual change process as a new basic learning value AG (i). The basic learning value AG (i) updated in this way is a correction term for steadily correcting the ignition timing so as to suppress the occurrence of knock. After the basic learning value AG (i) is updated, the basic learning value AG (i) is suppressed so that the basic learning value AG (i) does not become an excessively large value or an excessively small value. i) is subjected to an upper limit guard based on the upper limit guard value UGa and a lower limit guard based on the lower limit guard value LGa.

  By the way, if the engine 1 deteriorates over time, such as deposit deposits in the combustion chamber 2, knocking is likely to occur in the engine 1, so that the basic learning value AG (i) is reduced to a value based on this. Updated. The basic learning value AG (i) updated in this way is considered to be a value corresponding to the shift amount when the knock limit of the ignition timing shifts to the retard side due to the aging of the engine 1. Therefore, by correcting the ignition timing (directly the knock limit ignition timing (BT-R)) using the updated basic learning value AG (i), knocking is likely to occur due to aging deterioration of the engine 1. Suppression of becoming.

  However, the influence on the occurrence of knock due to the aging of the engine 1 may vary greatly depending on the engine operating area in the area i even in the same basic learning area i. In this case, when the ignition timing is corrected using the basic learning value AG (i) set for each basic learning region i, the basic learning value AG (i) depends on the engine operating state in the basic learning region i. ) May become an inappropriate value for suppressing the occurrence of knock due to deterioration of the engine 1 over time. Specifically, in suppressing the occurrence of knocking, the basic learning value AG (i) becomes too large to prevent the knocking occurrence effectively, or the basic learning value AG (i) is too small. As a result, the ignition timing may be excessively corrected to the retard side, leading to a decrease in the output of the engine 1.

As a countermeasure against the above-described problems, in this embodiment, the ignition timing control of the engine 1 is performed based on the ignition timing command value ST obtained from the following equation (1).
ST = (BT−R) + F + AG (i) + AGdp (n) (1)
ST: Ignition timing command value
(BT-R): knock limit ignition timing
BT: Base ignition timing
R: Knock margin
F: Feedback term
AG (i): Basic learning value
AGdp (n): Multi-point learning value The multi-point learning value AGdp (n) of the equation (1) is a knock caused by the aging deterioration of the engine 1 such as deposit adhesion in the combustion chamber 2. This is a correction term for correcting the ignition timing corresponding to the variation in the influence on the generation.

  This multi-point learning value AGdp (n) is further divided into areas in the basic learning area i that have a large variation in the influence on the occurrence of knock due to aging deterioration of the engine 1 than in the basic learning area i. Prepared for each of the plurality of multi-point learning areas n. Then, among the multipoint learning values AGdp (n) of each multipoint learning area n, the one corresponding to the multipoint learning area n with the current engine operating state when the engine 1 is operating is updated based on the feedback term F. . Specifically, in the same manner as the update of the basic learning value AG (i), the value obtained by subjecting the feedback term F to the gradual change process is set as a new multipoint learning value AGdp (n), whereby the multipoint learning value AGdp (n ) Will be updated. Accordingly, in a region where the variation in the influence on the occurrence of knock due to aging of the engine 1 in the basic learning region i is large, the multipoint learning value AGdp (for each multipoint learning region n obtained by subdividing the region according to the variation. Each of n) can be set to an appropriate value for suppressing the occurrence of knocking. When the current engine operating state is in the multipoint learning area n, the basic learning value AG (i) of the basic learning area i in which the multipoint learning area n exists is not updated based on the feedback term F. To be done.

  As the multipoint learning value AGdp (n) of the equation (1), when the current engine operating state is in any of the plurality of multipoint learning regions n, it corresponds to the multipoint learning region n having the same engine operating state. Used. Further, when the current engine operating state is not in any of the plurality of multipoint learning regions n, the multipoint learning value AGdp (n) of Expression (1) is set to “0”. For this reason, when the current engine operating state is not in any of the plurality of multipoint learning regions n, the ignition timing command value ST is calculated without using the multipoint learning value AGdp (n). Correction by the same multipoint learning value AGdp (n) of the ignition timing is also not performed.

  By performing ignition timing control of the engine 1 based on the ignition timing command value ST obtained from the above equation (1), in a region where the variation in the influence on knock occurrence due to aging of the engine 1 in the basic learning region i is large, Correction based on the basic learning value AG (i) and the multipoint learning value AGdp (n) is applied to the knock limit ignition timing (BT-R). This multi-point learning value AGdp (n) is a plurality of multi-point learning that is divided more finely than the basic learning area i in an area where the variation in the influence on knock occurrence due to aging of the engine 1 in the basic learning area i is large. It is prepared for each region n, and the one corresponding to the multipoint learning region n with the current engine operating state is used.

  By correcting the knock limit ignition timing (BT-R) using the multipoint learning value AGdp (n), even in the basic learning region i where the variation in the influence of knocking due to the aging of the engine 1 is large, It is possible to accurately suppress the occurrence of steady knocking in the engine 1 due to the same aging deterioration or the like. In other words, in the basic learning area i, in which the variation in the influence of knock generation due to the aging of the engine 1 is large, the knock occurrence in the engine 1 cannot be effectively suppressed, or the ignition timing is excessive. It is possible to suppress the occurrence of a problem that the output of the engine 1 is reduced by being corrected to the retard side.

  FIG. 2 shows an outline of calculation of the ignition timing command value ST when the engine operating state is in the multipoint learning region n and the multipoint learning value AGdp (n) in the region n is a negative value. FIG. 3 shows an outline of calculation of the ignition timing command value ST when the engine operating state is in the multipoint learning region n and the multipoint learning value AGdp (n) of the region n is a positive value. Yes. As shown in these figures, with respect to the ignition timing command value ST, the knock limit ignition timing (BT-R) is corrected by the multipoint learning value AGdp (n) corresponding to the multipoint learning region n. In addition to the correction, a correction by the basic learning value AG (i) corresponding to the basic learning area i where the multipoint learning area n exists is added. In this state, when the feedback term F is increased or decreased according to the presence or absence of the occurrence of knocking, the ignition timing command value ST is increased or decreased as indicated by the arrow Y1 or the arrow Y2 by the increase or decrease of the feedback term F. The multipoint learning value AGdp (n) is updated by using the value obtained by gradually changing the increasing / decreasing feedback term F as a new multipoint learning value AGdp (n). The upper limit guard and the lower limit guard of the point learning value AGdp (n) are performed.

  FIG. 4 shows the basic learning area i and the multipoint learning area n. In this example, a basic learning region i (i = 1, 2, 3) divided into three according to the engine speed is set as the basic learning region i. Further, in the basic learning region i (i = 1) that exists on the lowest rotation side with respect to the change direction of the engine rotation speed among the plurality of basic learning regions i, the region on the low load side with respect to the change direction of the engine load is A plurality of multi-point learning areas n are set. This is because, in such a region, variation in the degree of influence on the occurrence of knock due to aging of the engine 1 becomes large. Then, the same region is divided into four with respect to the change direction of the engine rotation speed and is divided into six with respect to the change direction of the engine load, and a total of 24 multi-point learning regions n (n = 1 to 24) are included in that region. Is set. Therefore, for the multipoint learning region n, the number in the engine load direction is larger than the number in the engine rotation direction. This is because, in a region where the variation in the influence on the occurrence of knock due to the aging of the engine 1 is large, the variation is larger in the direction of change in the engine load than in the direction of change in the engine speed and is wide. This is because there is a tendency, and it is possible to cope with the large variation based on such a tendency.

  Here, regarding the change in the ignition timing command value ST depending on whether or not the engine 1 has deteriorated over time, the difference between the multipoint learning region n in the basic learning region i (i = 1) on the lowest rotation side and the other regions. Will be described with reference to FIGS.

  FIG. 5 shows an example of a change in the ignition timing command value ST depending on whether or not the engine 1 has deteriorated over time in an area other than the multipoint learning area n in the basic learning area i (i = 1). Note that the solid line and the broken line in the figure are the transitions of the ignition timing command value ST with respect to changes in the engine load under the condition of constant engine speed, and the transitions without aging of the engine 1 (solid lines). And the transition with aged deterioration (two-dot chain line).

  In this figure, when the engine 1 is deteriorated over time and knocking is likely to occur, the ignition timing command value ST is delayed with a uniform width from the state indicated by the solid line to the state indicated by the broken line with a uniform width. It changes to the corner side. The amount of change of the ignition timing command value ST toward the retard side is such that the basic learning value AG (i) in the basic learning region i is retarded so as to suppress the occurrence of knocking due to the occurrence of aging deterioration of the engine 1. It corresponds to the changed part. In regions other than the multi-point learning region n in the basic learning region i (i = 1), knocking is likely to occur due to aging of the engine 1, and the ignition timing based on the basic learning value AG (i) It can be suppressed through correction. This is because the influence on the occurrence of knock due to the aging of the engine 1 is almost uniform in the above region.

  On the other hand, FIG. 6 shows a region in which each multipoint learning region n is set in the basic learning region i (i = 1) (here, a region corresponding to the multipoint learning region n where n = 1 to 6, for example). 2 shows an example of a change in the ignition timing command value ST depending on whether or not the engine 1 has deteriorated over time. Note that the solid line and the broken line in the figure are the transitions of the ignition timing command value ST with respect to changes in the engine load under the condition of constant engine speed, and the transitions without aging of the engine 1 (solid lines). And the transition with aged deterioration (two-dot chain line).

  In this figure, when the engine 1 is deteriorated over time and knocking is likely to occur, the ignition timing command value ST changes from the state indicated by the solid line to the state indicated by the broken line with a different width for each engine load on the retard side. Change. The amount of change of the ignition timing command value ST toward the retard side suppresses the occurrence of knock associated with the occurrence of aging deterioration of the engine 1 in addition to the amount of change of the basic learning value AG (i) toward the retard side. Accordingly, the amount of change of the multipoint learning value AGdp (n) of each multipoint learning area n to the retard side is also included. In the region where each multi-point learning region n in the basic learning region i (i = 1) is set, it is based on the multi-point learning value AGdp (n) that knocking is likely to occur due to aged deterioration of the engine 1. It can be suppressed through correction of the ignition timing. This is because, even if the degree of influence on knock occurrence due to aging of the engine 1 varies greatly for each multipoint learning region n, the multipoint learning value AGdp for each multipoint learning region n subdivided in consideration of the variation This is because (n) is updated to an appropriate value for suppressing the occurrence of knocking, and the ignition timing is corrected using these multipoint learning values AGdp (n).

  Incidentally, regarding the influence on the occurrence of knock due to the aging deterioration of the engine 1 in a plurality of multipoint learning areas n, among the multipoint learning areas n (FIG. 4), the multipoints on the low rotation side in the direction of change in the engine speed The learning area n becomes larger. Furthermore, regarding the above-described influence, there is a multi-point learning area n (for example, a multi-point learning area n at the center of the engine load direction) where the influence is maximized with respect to the change direction of the engine load in the multiple multi-point learning areas n The smaller the multi-point learning area n is, the smaller the area n is. Therefore, each multipoint learning value AGdp (n) becomes smaller as it corresponds to the multipoint learning area n located on the low rotation side of the engine 1, and the multipoint learning area where the above-mentioned influence becomes maximum in the engine load direction. The one corresponding to the region n closer to n tends to be smaller.

Next, guard processing of the multipoint learning value AGdp (n) will be described.
Similarly to the basic learning value AG (i), the multipoint learning value AGdp (n) is also not changed to an excessively large value or an excessively small value at the time of updating. It is necessary to perform upper limit guard and lower limit guard after updating). However, regarding the lower limit guard of the multipoint learning value AGdp (n), the same lower limit guard value as the lower limit guard of the basic learning value AG (i) is applied to the multipoint learning value AGdp (n) of a plurality of multipoint learning regions n. If the lower limit is uniformly guarded using LGa, it is inevitable that the problem described in the column “Problems to be solved by the invention” occurs.

  That is, if each multipoint learning value AGdp (n) is uniformly guarded based on the above-described lower limit guard value LGa, all the multipoint learning values AGdp (n) are thereby effectively knocked out in the engine 1. Therefore, it is difficult to reduce the ignition timing to a value that can be suppressed and to prevent the ignition timing from becoming excessively retarded. In other words, among the plurality of multipoint learning regions n, which is a region where the variation in the influence on knock occurrence due to the aging of the engine 1 is large, correction of the ignition timing by the multipoint learning value AGdp (n) in any one of the regions n. Even if it performs, the possibility that one of the malfunctions shown in the following [1] and [2] will arise becomes high.

  [1] The ignition timing is set until the multipoint learning value AGdp (n) is excessively guarded on the increase side (advance side) by the lower limit guard value LGa and the occurrence of knocking in the engine 1 can be effectively suppressed. I can't delay.

  [2] In the lower limit guard of the multipoint learning value AGdp (n) based on the lower limit guard value LGa, the lower limit guard is not performed until the multipoint learning value AGdp (n) is excessively decreased (retarded). As a result, the ignition timing is excessively retarded and the engine output is reduced.

  Therefore, in the present embodiment, each multipoint learning is performed as the lower limit guard value of the multipoint learning value AGdp (n) according to the degree of the influence on the occurrence of knock due to the aging deterioration of the engine 1 for each of the plurality of multipoint learning areas n. A different lower limit guard value LGb (n) is set for each region n.

  Here, regarding the influence on the occurrence of knock due to the aging deterioration of the engine 1, among the plurality of multipoint learning areas n, the multipoint learning area n on the low-rotation side in the change direction of the engine rotation speed becomes larger, and the engine load is increased. As described above, the change direction has a multipoint learning region n where the influence is maximized and becomes smaller as the multipoint learning region n is closer to the region n. Accordingly, with respect to the lower limit guard value LGb (n), each multipoint corresponds to the fact that the degree of influence on the occurrence of knock due to aging of the engine 1 differs for each of the multipoint learning areas n as described above. A different value is set for each learning region n. More specifically, the lower limit guard value LGb (n) of each multi-point learning area n is set to a smaller value in the multi-point learning area n on the low rotation side with respect to the change direction of the engine rotation speed, and the change direction of the engine load. Is set to a minimum value in the multipoint learning region n where the above influence is maximum, and a multipoint learning region closer to the region n is set to a smaller value.

  Then, when the multipoint learning value AGdp (n) of the predetermined multipoint learning area n is updated, the updated multipoint using the lower limit guard value LGb (n) corresponding to the multipoint learning area n The learning value AGdp (n) is guarded at the lower limit.

  The multipoint learning value AGdp (n) which is guarded based on the lower limit guard value LGb (n) is the influence of the influence on the occurrence of knock due to the aging deterioration of the engine 1 in the basic learning region i (i = 1 in this example). In a region where the variation is large, the value is appropriate for suppressing the occurrence of knocking according to the variation. In other words, the multipoint learning value AGdp (n) is a value that is so large that the occurrence of knocking in the engine 1 cannot be effectively suppressed by the lower limit guard based on the lower limit guard value LGb (n), and the ignition timing is excessively retarded. The value does not become so small that the engine output decreases. This is because the lower limit guard value LGb (n) for guarding the lower limit of the multipoint learning value AGdp (n) depends on the degree of influence on the occurrence of knock due to the aging deterioration of the engine 1 for each multipoint learning area n. This is because a different value can be set for each multi-point learning area n, and an optimum value is set as described above for each multi-point learning area n depending on the degree of the influence.

  Therefore, in the basic learning area i, the variation of the influence on the occurrence of knock due to the aging of the engine 1 is large, that is, in each multi-point learning area n, due to the lower limit guard of the multi-point learning value AGdp (n). Thus, it becomes possible to avoid the occurrence of knocking effectively and the reduction in engine output.

  Next, an execution procedure of various guard processes related to the calculation of the ignition timing command value ST will be described with reference to a flowchart of FIG. 7 showing a guard process routine. This guard processing routine is periodically executed through the electronic control unit 26, for example, with a time interruption every predetermined time.

  In this routine, various guard processes such as a guard process for basic learning values AG (i) (S101 to S103) and a guard process for multipoint learning values AGdp (n) (S104 to S106) are executed.

  As the guard process (S101 to S103) of the basic learning value AG (i), it is first determined whether or not the basic learning value AG (i) has been updated (S101). If the determination is affirmative, the updated basic learning value AG (i) is subjected to upper limit guard using the upper limit guard value UGa (S102). Specifically, if the updated basic learning value AG (i) is larger than the upper limit guard value UGa, the upper limit guard value UGa is set to a new basic learning value AG (i), and the updated basic learning value AG ( If i) is less than or equal to the upper guard value UGa, the basic learning value AG (i) is left as it is.

  Thereafter, the updated basic learning value AG (i) is subjected to the lower limit guard using the lower limit guard value LGa. Specifically, if the updated basic learning value AG (i) is smaller than the lower limit guard value LGa, the lower limit guard value LGa is set to a new basic learning value AG (i), and the updated basic learning value AG ( If i) is equal to or greater than the lower guard value LGa, the basic learning value AG (i) is used as it is. Note that, as the upper limit guard value UGa and the lower limit guard value LGa described above, optimum values determined in advance through experiments or the like are employed.

  As the guard process (S104 to S106) of the multipoint learning value AGdp (n), it is first determined whether or not the multipoint learning value AGdp (n) has been updated (S104). If the determination is affirmative, the updated multi-point learning value AGdp (n) is guarded using the upper guard value UGb (S105). Specifically, if the updated multipoint learning value AGdp (n) is larger than the upper limit guard value UGb, the upper limit guard value UGb is set to a new multipoint learning value AGdp (n), and the updated multipoint learning is performed. If the value AGdp (n) is less than or equal to the upper guard value UGb, the multipoint learning value AGdp (n) is left as it is. The upper limit guard value UGb here is a value common to each multipoint learning region n, and an optimum value determined in advance through experiments or the like is employed.

  Thereafter, the updated multipoint learning value AGdp (n) is subjected to lower limit guard using the corresponding lower limit guard value LGb (n) of the multipoint learning region n (S106). Specifically, if the updated multipoint learning value AGdp (n) is smaller than the lower limit guard value LGb (n), the same lower limit guard value LGb (n) is set to a new multipoint learning value AGdp (n), If the updated multipoint learning value AGdp (n) is equal to or greater than the lower limit guard value LGb (n), the multipoint learning value AGdp (n) is set as it is.

  Next, the basic learning value AG (i) corresponding to the basic learning region i in the region other than the multipoint learning region n in the basic learning region i (i = 1) on the lowest rotation side is updated based on the feedback term F. A reflection process that suppresses the influence of the change on the ignition timing in the multipoint learning area when the basic learning value AG (i) changes will be described.

  When the basic learning value AG (i) changes as described above, the influence of the change also reaches the ignition timing command value ST calculated in the multipoint learning region n. This is because the ignition timing command value ST in the multi-point learning region n is changed to the basic learning value AG (i) and the multi-point learning value AGdp (n) changed as described above, as can be seen from the equation (1). It is because it is calculated based on. When the ignition timing command value ST is calculated for the first time after the transition to the multi-point learning region n after the change in the basic learning value AG (i) occurs, the ignition timing command value ST is knocked by the change. There is a possibility that it becomes an inappropriate value for suppression, or it becomes a value causing a decrease in engine output due to a change to the retard side too much. The reflection process is executed in order to suppress the occurrence of problems related to the ignition timing in the multipoint learning region n.

  FIG. 8 is a flowchart showing a reflection processing routine for executing the reflection processing. This reflection processing routine is periodically executed through the electronic control unit 26, for example, with a time interruption at predetermined time intervals.

  In this routine, it is first determined whether or not the basic learning value AG (i) has changed in the basic learning region i (i = 1) on the lowest rotation side (S201). If the determination is affirmative, the basic learning value AG (i) changes on condition that the flag X for permitting or prohibiting the execution of reflection processing is “1 (permitted)” (S202: YES). A change amount ΔAG when calculated is calculated (S203). Then, the multipoint learning value AGdp (n) of each multipoint learning region n is changed in the opposite direction to the change direction of the basic learning value AG (i) by the same change amount ΔAG (S204).

  As described above, the occurrence of the above-described problems can be suppressed by changing each multipoint learning value AGdp (n) in accordance with the change in the basic learning value AG (i). More specifically, when the ignition timing command value ST is calculated for the first time after the basic learning value AG (i) has changed, the ignition timing command value ST is calculated for the first time after moving to the multipoint learning region n. Thus, it is possible to suppress an inappropriate value for suppressing the occurrence of knocking or a value that causes a decrease in engine output due to excessive change to the retard side.

  Next, when the multipoint learning value AGdp (n) is always guarded at the lower limit and stuck to the lower limit guard value LGb (n) in the multipoint learning area n, the basic that the multipoint learning area n exists is A reduction process for reducing the basic learning value AG (i) in the learning region i (i = 1) to retard the ignition timing as much as possible will be described.

  In a situation where there are many knocks in the multipoint learning area n and the multipoint learning value AGdp (n) is stuck to the lower limit guard value LGb (n) based on the occurrence of knocking, the basic learning area i with the multipoint learning area n ( When the basic learning value AG (i) of i = 1) has a margin with respect to the lower limit guard value LGa, it is preferable to suppress the occurrence of knocking as much as possible by also performing the ignition timing retardation for the margin. . In order to realize such ignition timing retardation, the above-described reduction process is executed.

  FIG. 9 is a flowchart showing a weight reduction processing routine for executing the above weight reduction processing. This weight reduction processing routine is periodically executed through the electronic control unit 26, for example, with a time interruption at predetermined time intervals.

  In this routine, it is first determined whether or not the multipoint learning value AGdp (n) is stuck to the lower limit guard value LGb (n) (S301). If the determination is affirmative, the multipoint learning region n is determined. The basic learning value AG (i) of the basic learning area i (i = 1) in which is present is reduced by a predetermined value S (S302). With respect to the reduction of the predetermined value S relative to the basic learning value AG (i), the multipoint learning value AGdp (n) is stuck to the lower limit guard value LGb (n) and is executed each time the process proceeds to step S302. It will be. Therefore, if the basic learning value AG (i) has a margin with respect to the lower limit guard value LGa, the basic learning value AG (i) is reduced through the reduction of the basic learning value AG (i) each time the process proceeds to step S302. (i) is reduced until it reaches the lower guard value LGa. After the basic learning value AG (i) reaches the lower limit guard value LGa, the basic learning value AG (i) is not further reduced.

  After the basic learning value AG (i) is reduced by the predetermined value S in step S302, it is determined whether or not the basic learning value AG (i) has changed (S303: YES). Here, the fact that the basic learning value AG (i) does not change means that the basic learning value AG (i) has reached the lower limit guard value LGa, and the lower limit guard based on the lower limit guard value LGa is performed. It means that there is a situation. On the other hand, the fact that the basic learning value AG (i) has changed means that the basic learning value AG (i) has changed toward the lower guard value LGa, and the reflection processing described above is not executed. The flag X is set to “0 (prohibited)” (S304).

  If the basic learning value AG (i) is reduced (decrease in the weight reduction process) in step S302, the reflection process is executed and the multipoint learning value AGdp (n) is changed to the increase side. Then, the multipoint learning value AGdp (n) becomes inappropriate as a value for suppressing steady knock occurrence in the engine 1 due to aging deterioration of the engine 1 or the like. However, when the basic learning value AG (i) is reduced through the reduction process, the execution of the reflection process is prohibited by setting the flag X to “O (prohibited)”. As a result, the multipoint learning value AGdp (n) becomes the above-described inappropriate value, and accordingly, the occurrence of steady knocking of the engine 1 due to the deterioration of the engine 1 in the multipoint learning region n cannot be suppressed. This is avoided.

  After the sticking of the multi-point learning value AGdp (n) at the lower limit guard value LGb (n) has occurred and the sticking is eliminated (S305: YES), the basic learning value AG (i) is reduced by the weight reduction process. The basic learning value AG (i) is returned to the state before the weight reduction by the weight reduction processing. Therefore, the ignition timing is not retarded more than necessary based on the reduction of the basic learning value AG (i) by the above reduction process. As a situation in which the sticking of the multipoint learning value AGdp (n) to the lower limit guard value LGb (n) is eliminated, for example, the current engine operating state shifts to another multipoint learning region n and multipoint learning is performed. For example, the value AGdp (n) is switched, and the multipoint learning value AGdp (n) after the switching is larger than the lower limit guard value LGb (n) corresponding thereto.

  When the sticking at the lower limit guard value LGb (n) of the multipoint learning value AGdp (n) has not occurred or when the sticking has been resolved as described above, a negative determination is made in step S301, and the reflection processing is not performed. The flag X for determining execution permission and prohibition is set to “0 (permission)” (S307). As a result, the reflection process can be executed.

According to the embodiment described in detail above, the following effects can be obtained.
(1) Regarding the lower limit guard value LGb (n) of the multi-point learning value AGdp (n) prepared for each of the plurality of multi-point learning areas n, knocking occurs due to deterioration over time of the engine 1 in each of the multi-point learning areas n Since each multipoint learning region n is set to a different value according to the degree of the influence, it is possible to set an optimum value according to the degree of the influence. The multipoint learning value AGdp (n) which is guarded based on the lower limit guard value LGb (n) has an influence on the occurrence of knocking due to the deterioration of the engine 1 over time in the basic learning region i (i = 1 in this example). In a region where the variation of the noise is large, the value is appropriate for suppressing the occurrence of knocking according to the variation. In other words, the multipoint learning value AGdp (n) is a value that is so large that the occurrence of knocking in the engine 1 cannot be effectively suppressed by the lower limit guard based on the lower limit guard value LGb (n), or the ignition timing is excessively retarded. The value does not become so small that the engine output decreases. Accordingly, in the basic learning region i, in the region where the variation in the influence on the occurrence of knock due to the aging of the engine 1 is large, that is, in the multi-point learning region n, due to the lower limit guard of the multi-point learning value AGdp (n). Thus, it becomes possible to avoid the occurrence of knocking effectively and the reduction in engine output.

  (2) For a region in the basic learning region i that has a large variation in the influence on knock occurrence due to aging of the engine 1, the basic learning region i (i = 1) on the lowest rotation side among the plurality of basic learning regions i. ) In the low load side. And in the area | region where the dispersion | variation to the influence on knock generation by the aged deterioration of the said engine 1 is large, the dispersion | variation tends to become large in the change direction of an engine load compared with the change direction of an engine speed. Based on such a tendency, a plurality of multipoint learning areas n are set in the low load side area in the lowest rotation side multipoint learning area n, and the engine load change direction in the multipoint learning area n (6 in this example) is greater than the number (4 in this example) in the direction of change in engine speed. For this reason, even if the above-mentioned variation becomes large in the direction of change of the engine load in the region on the low engine load side and reaches a wide range, such large variation can be dealt with.

  (3) Regarding the influence on the occurrence of knock due to the aging deterioration of the engine 1 in each multipoint learning area n, among the multiple multipoint learning areas n, the multipoint learning area on the low rotation side in the direction of change of the engine rotation speed As the engine load changes, there is a multipoint learning area n where the above-mentioned influence is maximized, and the multipoint learning area n closer to the same area n becomes smaller. The lower limit guard value LGb (n) in each multipoint learning region n is set corresponding to the degree of influence on the occurrence of knock due to the aging deterioration of the engine 1 in each multipoint learning region n. In other words, the lower limit guard value LGb (n) is set to a smaller value for the low-rotation-side multipoint learning region n for the direction of change of the engine speed, and the above-mentioned influence is maximized for the direction of change of the engine load. The multipoint learning area n becomes the minimum value, and the multipoint learning area n closer to the same area n is set to a smaller value. Therefore, for each multipoint learning value AGdp (n) that is lower limit guarded by these lower limit guard values LGb (n), knock generation is accurately performed according to the variation in the influence on knock occurrence due to aging of the engine 1. The ignition timing is retarded so that it can be effectively suppressed, and the ignition output is retarded excessively so that the engine output does not decrease.

  (4) In the multi-point learning area n, the lower limit guard value LGb (n) of the multi-point learning value AGdp (n) is reduced as the multi-point learning value AGdp (n) is reduced in order to suppress the occurrence of knock. When the sticking occurs, there is a possibility that the basic learning value AG (i) of the basic learning area i where the multipoint learning area n exists has a margin with respect to the lower limit guard value LGa. When the multipoint learning value AGdp (n) is stuck to the lower limit guard value LGb (n), the basic learning value AG (i) of the basic learning area i where the multipoint learning area n exists is reduced. A weight reduction process is executed to retard the ignition timing as much as possible. When the basic learning value AG (i) is decreased until the lower limit guard value LGa is reached and the lower limit guard is reached through the execution of such a weight reduction process, the ignition timing is retarded thereby suppressing the occurrence of knocking. It becomes. Therefore, in order to suppress the occurrence of knocking in the engine 1, the margin of the basic learning value AG (i) with respect to the lower limit guard value LGa can be used effectively. When the sticking of the multipoint learning value AGdp (n) to the lower limit guard value LGb (n) is resolved, the reduction of the basic learning value AG (i) by the weight reduction process is stopped, and the basic learning value AG ( Since i) is returned to the state before the reduction, the ignition timing is not delayed more than necessary based on the reduction of the basic learning value AG (i).

  (5) In an area other than the multipoint learning area n within the basic learning area i on the low rotation side, the basic learning value AG (i) of the basic learning area i is updated and changed based on the feedback term F. When the basic learning value AG (i) changes in this way, when the engine operating state shifts to the multipoint learning region n in the basic learning region i, the ignition timing after the transition is the basic learning value AG (i). As a result, the ignition timing may become an inappropriate value for suppressing the occurrence of knocking, or may be too retarded to cause a decrease in engine output. For such a problem, reflection control is executed when the change in the basic learning value AG (i) occurs, and each multipoint learning region n is changed by the change amount ΔAG when the basic learning value AG (i) changes. This multi-point learning value AGdp (n) is avoided by being changed in the direction opposite to the direction of change of the basic learning value AG (i). However, when the basic learning value AG (i) changes to the reduction side through the execution of the reduction process, if the reflection process is executed and each multipoint learning value AGdp (n) changes to the increase side, the multipoint The learned value AGdp (n) becomes inappropriate as a value for suppressing steady knock occurrence in the engine 1 due to aging deterioration of the engine 1 or the like. Considering this, when the basic learning value AG (i) changes through execution of the weight reduction process, the execution of the reflection process is prohibited. As a result, the multipoint learning value AGdp (n) becomes an inappropriate value as described above, and accordingly, it is possible to suppress the occurrence of steady knocking in the engine 1 due to aging degradation of the engine 1 in the multipoint learning region n. It is avoided that it disappears.

In addition, the said embodiment can also be changed as follows, for example.
When the current engine operating state is in the multipoint learning area n, the basic learning value AG (i) is set to “0” and only the multipoint learning value AGdp (n) corresponding to the multipoint learning area n is set. However, it may be used as a correction term for steadily correcting the ignition timing in order to suppress the occurrence of knock. In this case, the reflection process and the weight reduction process are omitted.

In a plurality of multipoint learning areas n, the number in the engine load change direction may be equal to or less than the number in the engine rotation speed change direction.
-You may change suitably the total number of the multipoint learning area | region n.

In the basic learning area i on the lowest rotation side, the multipoint learning area n may be set in an area other than the area on the low load side.
A multi-point learning area may be set in an area i (i = 2, 3) other than the basic learning area i on the lowest rotation side according to the influence on the occurrence of knock when the engine 1 deteriorates over time.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole engine to which the ignition timing control apparatus of this embodiment is applied. Explanatory drawing which shows the outline | summary of calculation of an ignition timing command value. Explanatory drawing which shows the outline | summary of calculation of an ignition timing command value. Explanatory drawing which shows a basic learning area | region and a multipoint learning area | region. The graph which showed an example of transition of the ignition timing command value in areas other than the multipoint learning area in the basic learning area on the lowest rotation side, and changes in the above-mentioned transition of the ignition timing command value depending on the presence or absence of engine aging. The graph which showed an example of the transition of the ignition timing command value in a multipoint learning area, and the change of the said transition of the ignition timing command value by the presence or absence of aged deterioration of an engine. The flowchart which shows the execution procedure of the various guard processes relevant to calculation of ignition timing command value. The flowchart which shows the execution procedure of reflection processing. The flowchart which shows the execution procedure of a weight reduction process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust passage, 26 ... Electronic control unit, 27 ... Accelerator pedal, 28 ... Accelerator position sensor, 29 ... Throttle valve, 30 ... Throttle position sensor, 31 ... Knock sensor, 32 ... Air flow meter, 34 ... Crank position sensor.

Claims (5)

An ignition timing control device for controlling the ignition timing of an internal combustion engine to be retarded as the command value decreases based on the ignition timing command value, wherein the ignition timing command value is calculated based on an engine operating state. The ignition timing is calculated by adding a correction by a feedback term that increases or decreases depending on whether knocking occurs or not, and by adding a correction by a basic learning value updated based on the feedback term. Is prepared for each of the plurality of basic learning areas divided according to the engine operating state, and the value of the basic learning area corresponding to the current engine operating state is updated based on the feedback term, and the lower limit guard is set after the update. In the ignition timing control device for an internal combustion engine in which the applied value is used for correcting the knock limit ignition timing,
A plurality of multi-point learning that is divided in accordance with the engine operating state in an area that is within at least one of the plurality of basic learning areas and in which the influence on the occurrence of knock due to aging of the internal combustion engine varies. A multi-point learning value used for correction of the knock limit ignition timing is prepared for each multi-point learning region, and an area is set.
Regarding the multipoint learning value, when the current engine operating state is in the multipoint learning area, the value of the multipoint learning area is updated based on the feedback term, and after the update, the lower limit guard based on the lower limit guard value is applied. Used to correct the knock limit ignition timing,
The lower limit guard value of the multipoint learning value is set to a different value for each multipoint learning area according to the degree of the influence on the occurrence of knock due to aging deterioration of the internal combustion engine in each of the plurality of multipoint learning areas. An ignition timing control device for an internal combustion engine, characterized by comprising: The plurality of basic learning areas are partitioned according to the engine speed,
As for the multi-point learning region, among the plurality of basic learning regions, the engine rotational speed change direction is set to a region on the engine low load side in the lowest learning side basic learning region, and the engine rotational speed and engine The ignition timing control device for an internal combustion engine according to claim 1, wherein the ignition timing control device is divided according to a load, and the number in the engine load direction is larger than the number in the engine rotation direction. The plurality of basic learning areas are partitioned according to the engine speed,
The multi-point learning region is set to a region on the engine low load side in the basic learning region on the lowest rotation side in the change direction of the engine rotation speed among the plurality of basic learning regions, and the engine rotation speed and the engine load Is divided according to
The lower limit guard value of the multipoint learning value is set to a smaller value in the multipoint learning area on the low rotation side with respect to the change direction of the engine rotation speed, and the lower limit guard value is the minimum value with respect to the change direction of the engine load. The ignition timing control device for an internal combustion engine according to claim 1, wherein a multipoint learning region is set such that a multipoint learning region closer to the same region is set to a smaller value. When the current engine operating state is in the multi-point learning region, the knock limit ignition timing is corrected by the basic learning value of the basic learning region in which the multi-point learning region exists, and the multi-point learning region Correction by point learning value is added,
When the multi-point learning value is stuck to the lower limit guard value in the multi-point learning region with the current engine operating state, the weight reduction process is executed to reduce the basic learning value of the basic learning region where the multi-point learning region exists. The ignition timing control of the internal combustion engine according to any one of claims 1 to 3, wherein when the sticking of the multipoint learning value to the lower limit guard value is resolved, the reduction of the basic learning value by the reduction process is stopped. apparatus. When the current engine operating state is in the multi-point learning region, the knock limit ignition timing is corrected by the basic learning value of the basic learning region in which the multi-point learning region exists, and the multi-point learning region Correction by point learning value is added,
Reflection processing for changing the multi-point learning value of each multi-point learning area in the direction opposite to the change direction of the basic learning value by the amount of change when the basic learning value changes in the basic learning area where the multi-point learning area exists. Is possible and
When the basic learning value changes through the update of the basic learning value based on the feedback term in the basic learning region where the multi-point learning region exists, the reflection processing is executed,
When the basic learning value of the basic learning area where the multi-point learning area exists changes through the execution of the weight reduction process based on the sticking of the multi-point learning value to the lower limit guard value in the multi-point learning area, the execution of the reflection process The ignition timing control device for an internal combustion engine according to claim 4, wherein

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