JPH04203240A - Self-diagnosis apparatus in fuel supply controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To successively monitor excessive degradation of an air-fuel ratio condition by diagnosing the air-fuel ratio control condition on the basis of at least one of the sizes of variation in an air-fuel vatio feed-back control amount and air fuel ratio variation controlling time thereby. CONSTITUTION:A detecting signal of air-fuel ratio of engine intake mixture detected by an air-fuel ratio detecting means A is inputted to an air-fuel ratio feedback control amount setting means B to set the air-fuel ratio feedback control amount on the basis of a deviation between the detected air-fuel ratio and a desired one compared with each other. An object to be controlled about the air-fuel ratio on the basis of the air-fuel ratio feedback control amount is controlled by an air-fuel ratio variation correction means C to correct the variation of air fuel ratio. Then, in an air-fuel ratio control diagnosing means D, a representative value of at least one of the sizes of variation in the air-fuel ratio feedback control amount and an air-fuel ratio variation control time by the air-fuel ratio feedback control amount within a predetermined period is compared with a slice level preset in every enging running requirement to diagnose the air-fuel ratio control condition.

Description

[Detailed Description of the Invention] <Industry> 2. Field of Application The present invention relates to a self-diagnosis device for a fuel supply control device for an internal combustion engine, and more specifically, the present invention relates to a self-diagnosis device for a fuel supply control device for an internal combustion engine. The present invention relates to a device that can perform diagnosis in correlation with exhaust characteristics.

<Prior art> Conventionally, in an internal combustion engine equipped with an electronically controlled fuel injection device having an air-fuel ratio feedback correction control function,
Publication No. 0-9094.4, JP-A-61-1.90142
As disclosed in Japanese Patent Publication No. 1, etc., there are some systems that employ learning control of the air-fuel ratio.

Air-fuel ratio feedback correction control uses the basic fuel injection amount 'Fp, which is calculated from parameters of engine operating conditions related to the amount of air taken into the engine (for example, intake air flow rate Q and engine rotational speed N), to the engine exhaust system. The actual air-fuel ratio is corrected by the air-fuel ratio feedback correction coefficient LMD, which is set by proportional/integral control based on the rich/lean ratio with respect to the target air-fuel ratio (for example, the stoichiometric air-fuel ratio) determined by the oxygen sensor installed in the The fuel ratio is feedback-controlled to the target air-fuel ratio.

Here, the deviation of the air-fuel ratio feedback correction coefficient LMD from the reference value (target convergence value) is learned for each of the predetermined plurality of operating regions, and the learning correction coefficient KBLRC is calculated.
is determined, and the basic fuel injection amount Tp is determined based on the learning correction coefficient KBL.
The base air-fuel ratio obtained without the correction coefficient LMD is corrected by RC so that it substantially matches the target air-fuel ratio, and during air-fuel ratio feedback control, the fuel injection amount Ti is calculated by further correcting with the correction coefficient LMD. It is.

As a result, it is possible to perform correction corresponding to the required value of air-fuel ratio correction that differs depending on the operating conditions, and the air-fuel ratio feedback correction coefficient L
It is possible to stabilize MD near the reference value and improve air-fuel ratio controllability.

<Problems to be Solved by the Invention> Incidentally, in electronically controlled fuel injection devices, the characteristics at the time of production may be caused in the components of the fuel supply control system such as the air flow meter that detects the amount of intake air, the fuel injection valve, and the fuel pump. When variations, failures, and deterioration occur, the base air-fuel ratio deviates from the target air-fuel ratio, and harmful components such as CO, HC, and NOx contained in the exhaust gas increase. Here, as a self-diagnosis method for detecting deterioration of exhaust properties due to deviations in the base air-fuel ratio, in a device having an air-fuel ratio compensation function as described above, the required correction value or operating range to obtain the target air-fuel ratio is used. The learning correction coefficient K B L RC learned for each
If this average value has a deviation of more than a predetermined value from the initial value, it is determined that the learning correction level has increased due to some abnormality in the fuel supply control system. Discrimination is considered.

However, as shown in Figures 14 to 17, even if the average base air-fuel ratio deviation is at the same level, the air-fuel ratio deviation characteristics change (slope) due to operating conditions (for example, intake air flow rate Q). In some cases, the characteristics of the exhaust properties are different, and in some cases the exhaust characteristics are within the regulation value level (as shown in Figure 14, there is no change in the error rate depending on the operating conditions), and in other cases, only NOx or There are cases where only C○ and HC exceed the regulation value (as shown in Figure 15 or 16, the error rate changes depending on the operating conditions).
It has been difficult to accurately determine the state of air-fuel ratio deviation that leads to deterioration of exhaust characteristics from the average value of the learning correction coefficient KBLRC, which indicates the average level of base air-fuel ratio deviation.

Also, until the air-fuel ratio learning described above has progressed sufficiently,
In situations where differences in correction requests due to differences in operating conditions cannot be adequately addressed, differences in the base air-fuel ratio may occur during transient periods.
This has an adverse effect on the exhaust properties (see Figure 11). Here, there is a request to perform self-diagnosis of the air-fuel ratio control state even in a state where such learning progress is insufficient, and to issue a warning of deterioration of exhaust characteristics, or if the correction request is sufficiently incorporated into the learning correction coefficient. If this is not done, it will not be possible to accurately self-diagnose the air-fuel ratio control status based on the learned values, and it will not be possible to issue a warning of deterioration in exhaust characteristics until learning has progressed sufficiently. There are also problems.

In this way, with self-diagnosis of the air-fuel ratio control state based on the average value of the learning correction coefficient KBLRC, it is difficult to perform a diagnosis that correlates with the exhaust characteristics, and it is difficult to perform a diagnosis that is correlated with the exhaust characteristics. However, there was a problem in that it could not be applied when it was desired to successively monitor the deterioration of the air-fuel ratio control condition such as exceeding the exhaust component regulation value.

The present invention has been made in view of the above problems, and is capable of diagnosing the air-fuel ratio control state by correlating it with the exhaust characteristics based on the feedback control of the air-fuel ratio. It is an object of the present invention to provide a diagnostic device that can successively monitor changes in air-fuel ratio control status.

<Means for Solving the Problems> Therefore, a self-diagnosis device in a fuel supply control device for an internal combustion engine according to the present invention is configured as shown in FIG.

In FIG. 1, the air-fuel ratio detection means detects the air-fuel ratio of the engine intake air-fuel mixture, and the air-fuel ratio feedback control amount setting means compares the detected actual air-fuel ratio with a target air-fuel ratio to determine the actual air-fuel ratio. An air-fuel ratio feedback control plate amount is set for correcting the air-fuel ratio of the engine intake air-fuel mixture so that the fuel ratio approaches the target air-fuel ratio.

Further, the air-fuel ratio increase/decrease correction means controls a controlled object related to the air-fuel ratio of the engine intake air-fuel mixture based on the air-fuel ratio feedback control oil amount to increase/decrease the air-fuel ratio.

The air-fuel ratio side faI diagnosis means determines the air-fuel ratio in the fuel supply control device based on at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount and the air-fuel ratio increase/decrease control time by the air-fuel ratio feedback control amount. Diagnose control status.

Here, the air-fuel ratio control diagnosis means determines a representative value within a predetermined period of at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount and the time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount, and the engine operation. Preferably, the configuration is such that the air-fuel ratio control state in the fuel supply control device is diagnosed by comparing the slice level with a preset slice level for each condition.

Further, the air-fuel ratio control diagnosis means determines a representative value within a predetermined period of at least one of the magnitude of increase/decrease change in the air-fuel ratio feedback control amount and the control time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount; It is also possible to diagnose the air-fuel ratio control state in the fuel supply control device by comparing the slice levels individually set on the air-fuel ratio increase control side and the air-fuel ratio decrease control side using the fuel ratio feedback control amount.

According to this configuration, since the air-fuel ratio feedback control amount is set so that the actual air-fuel ratio approaches the target air-fuel ratio, the movement of the air-fuel ratio feedback control amount changes depending on the deviation of the actual air-fuel ratio from the target air-fuel ratio. Specifically, the parameter indicating the air-fuel ratio deviation state is based on at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount and the control time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount. and diagnose the air-fuel ratio control status.

Here, when performing self-diagnosis of the air-fuel ratio control state using the parameters related to the air-fuel ratio feedback correction value as described above, it is necessary to use the representative values of the parameters within a predetermined period and the slices set in advance for each engine operating condition. By comparing the levels, diagnostic accuracy can be ensured in response to differences in the movement of the air-fuel ratio feedback control amount due to differences in operating conditions.

In addition, when performing self-diagnosis by comparison with the slice level as described above, it is necessary to set the slice level individually corresponding to the air-fuel ratio increase control side and the air-fuel ratio decrease control side, respectively. :1 Diagnosis can be made based on whether the base air-fuel ratio deviates towards the rich side or the lean side with respect to the standard air-fuel ratio.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing one embodiment, an internal combustion engine 1 is connected to an air cleaner 2 through an intake duct 3. Air is taken in via the throttle valve 4 and the intake manifold 5. A fuel injection valve 6 is provided in a branch portion of the intake manifold 5 for each cylinder. The fuel injection valve 6 is a normally closed electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped.
The valve is opened by being energized by a drive pulse signal from 2, and fuel is injected and supplied under pressure from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator.

Each combustion chamber of the engine 1 is provided with a spark plug 7, which ignites a spark to ignite and burn the air-fuel mixture. and,
From engine l, exhaust manifold 8, exhaust dugs 1 to 9.
Exhaust gas is discharged via a three-way catalyst 10 and a muffler 11.

The three-way catalyst 10 oxidizes and oxidizes NOx, CO, and HC.
It is reduced and converted into harmless components, and in order to obtain a high conversion rate through both oxidation and reduction, it is necessary to control the air-fuel ratio of the engine intake mixture to the stoichiometric air-fuel ratio. In the feedback control, control is performed using the stoichiometric air-fuel ratio as the target air-fuel ratio.

It is equipped with a microcomputer that includes a control unit RAM, an A/D converter, and an input/output interface, and receives input signals from various sensors, performs arithmetic processing as described below, and controls the operation of the fuel injection valve 6. Control.

As the various sensors mentioned above, an air flow meter 13 is provided in the intake duct l-3, and outputs a signal corresponding to the intake air flow rate Q of the engine 1.

Further, a crank angle sensor 14 is provided, and in the case of a four-cylinder engine, outputs a reference signal REF for every 180 degrees of crank angle and a unit signal POS for every 1 degree or 2 degrees of crank angle. Here, the engine rotational speed N can be calculated by measuring the period of the reference signal REF or the number of occurrences of the unit signal POS within a predetermined period of time.

Further, a water temperature sensor 15 is provided to detect the cooling water temperature Tw of the overjacket of the engine 1.

Further, an oxygen sensor 16 as an air-fuel ratio detection means is provided at the gathering part of the exhaust manifold 8, and detects the air-fuel ratio of the intake air-fuel mixture via the oxygen concentration in the exhaust gas. The oxygen sensor 16 is a known sensor that detects whether the actual air-fuel ratio is rich or lean with respect to the stoichiometric air-fuel ratio by utilizing the fact that the oxygen concentration in the exhaust gas changes suddenly after the stoichiometric air-fuel ratio.

Here, the CPU of the microcomputer as a control unit is shown in FIGS. 3 to 8.
Arithmetic processing is performed according to the programs on the ROM shown in flowchart 1 in the figure, and the fuel injection amount Ti is set while executing air-fuel ratio feedback correction control and air-fuel ratio learning correction control for each operating region, and the fuel injection amount Ti is In addition to controlling the fuel supply, the system also performs self-diagnosis of the air-fuel ratio control state in the electronically controlled fuel supply system having the following two configurations.

In this embodiment, the functions of the air-fuel ratio feedback control amount setting means, the air-fuel ratio increase/decrease correction means, and the air-fuel ratio control state diagnosis means are performed by software and software as shown in the flowcharts of FIGS. 3 to 8. are prepared for. Further, in this embodiment, the measured object related to the air-fuel ratio of the engine intake air-fuel mixture is the fuel injection amount.

The program shown in flowcharts l~ in Fig. 3 calculates the air-fuel ratio feedback correction coefficient LMD (air-fuel ratio feedback control amount), which is multiplied by the basic fuel injection amount Tp (←KXQ/N; is a constant), by proportional and integral This is a program set by control, and is executed every revolution (I rev) of the engine I. Note that the air-fuel ratio feedback correction coefficient L
The initial value of MD is 1, and the basic fuel injection amount Tp is adjusted so that the actual air-fuel ratio approaches the stoichiometric air-fuel ratio, which is the target air-fuel ratio.
The actual air-fuel ratio is varied around the target air-fuel ratio by increasing or decreasing the air-fuel ratio.

First, step 1 (indicated as Sl in the figure).

The same applies hereafter) reads the voltage signal output from the oxygen sensor (02/5) 16 according to the oxygen concentration in the exhaust gas.

Then, in the next step 2, the voltage signal from the oxygen sensor 16 read in step 1 is compared with a slice level (for example, 500 mV) corresponding to the target air-fuel ratio (stoichiometric air-fuel ratio) to determine the engine intake air-fuel mixture. It is determined whether the air-fuel ratio is rich or lean with respect to the target air-fuel ratio.

When the voltage signal from the oxygen sensor 16 is greater than the slice level and it is determined that the air-fuel ratio is rich, the process proceeds to step 3, where it is determined whether this is the current rich determination or the first time.

When the rich determination is made for the first time, the process proceeds to step 4, where the air-fuel ratio feedback correction coefficient LMD set up to the previous time is set to the maximum value a.

The fact that this is the first rich determination means that the previous lean determination was performed, and as a result, the air-fuel ratio feedback correction coefficient LMD was controlled to increase (-the fuel injection amount Ti was increased), and the rich Once it has been determined, the correction coefficient LMD is then controlled to decrease, so the value is either the value before the reduction control in the first rich determination or the maximum value of the correction coefficient LMD.

In the next step 5, a predetermined proportionality constant P is subtracted from the previous correction coefficient LMD to control the correction coefficient LMD to decrease, so that the air-fuel ratio becomes lean and approaches the target air-fuel ratio. Further, in the next step 6, 1 is set to "2 minute addition" which is a flag indicating that proportional control has been executed.

Furthermore, in the next step 7, in a state where the actual air-fuel ratio is determined to be lean with respect to the target, the control amount by the air-fuel ratio feedback correction coefficient LMD used to enrich (reduce) the air-fuel ratio is determined. SUMR indicating the summation
Update settings according to the following formula.

In the above calculation formula, (a-1)) is the change 1-11 (magnitude of increase/decrease change) in which the correction coefficient LMD was changed in order to enrich the air-fuel ratio in the previous air-fuel ratio lean state, and trn is the time during which air-fuel ratio enrichment control was performed in the previous air-fuel ratio lean state, and further,
K RE F is a correction coefficient that is set based on the basic fuel injection amount Tp (engine load) and the engine rotational speed N in step 93 of the flowchart shown in FIG.

That is, (a-b) , the change in correction coefficient LMD 1
1] (a-b) multiplied by the enrichment control time tm, and further corrects this value based on the engine operating conditions so that it can be treated equally even if the operating conditions are different. Then, add the total amount of enrichment control in the previous air-fuel ratio lean state to the sum of enrichment control amounts obtained up to the previous time, SUMR, to find the sum of enrichment control amounts within a predetermined period. be.

On the other hand, when it is determined in step 3 that the rich determination has not been completed, the process proceeds to step 8, and the value obtained by multiplying the integral constant 1 by the latest fuel injection amount Ti is subtracted from the previous correction coefficient LMD. The correction coefficient LMD is updated, and rx'r is calculated in step 8 every time this program is executed until the air-fuel ratio is released from the rich state and turned to lean.
Repeat the decrease control by i.

In addition, when it is determined in step 2 that the air-fuel ratio is lean relative to the actual air-fuel ratio or the target air-fuel ratio (theoretical air-fuel ratio), in the same way as in the rich determination, step 9 is performed to determine whether the current lean determination or the first time. If it is the first time, the process proceeds to step 10 and the correction coefficient L up to the previous time is determined.
MD, that is, the correction coefficient LMD, which was controlled to gradually decrease during rich determination, is set to the minimum value, and the next step 1 is performed.
In step 1, the proportional constant P is added to the previous correction coefficient LMD and updated to increase the fuel injection amount Ti.Furthermore, in step 12, the proportional control i is changed in the same manner as in step 6. 1 is set in the ``rp addition'' which is a flag indicating that the process has been executed.

In the next step 13, similarly to step 7, the sum sum SUML of lean control amounts used to lean (increase) the actual air-fuel ratio within a predetermined period is calculated.
is calculated according to the following formula.

On the other hand, if it is determined in step 9 that it is lean or not the first time, the process proceeds to step 14, and the value obtained by multiplying the integral constant 1 by the latest fuel injection amount Ti is applied to the previous correction coefficient L.
MD and gradually increases the correction coefficient LMD.

Correction at the first time of rich/lean discrimination [When proportional control of the number of threads LMD is executed, further, in step 15, tm indicating the control time for enrichment or lean is reset to zero.

The control time tm is the fifth control period executed every predetermined minute time period.
In step 84 of the flowchart in the figure, it is incremented by 1 every time the program is executed, or every predetermined minute time, so it is reset to zero every time the air-fuel ratio feedback correction coefficient LMD is proportionally controlled. The count I is incremented until the next proportional control, and the proportional control interval, d, measures the duration of lean or rich control.

From the next step 16 onwards, various processes related to air-fuel ratio learning correction control, which will be described later, are performed.

In this embodiment, as shown in FIG. 9, the entire operating region is divided into a plurality of regions using the basic fuel injection amount Tp and the engine speed N as parameters, and the air-fuel ratio learning correction value is set for each divided region. It is equipped with two learning maps that can be stored in a rewritable manner; one learning map divides the entire operating area into 16 unit areas using a 4x4 grid, and the other learning map divides the entire operating area into 16 unit areas using a 4x4 grid.
], the entire operating region is divided into 256 unit operating regions using 6 grids, and further divided into 4
It is intended to be subdivided into 4-16 sections. In addition, the air-fuel ratio learning correction value adapted to the entire operating range without dividing the operating range as shown in "-" is also separately learned and set.

In step 16, it is determined whether a count value cnt, which is used to determine whether the vehicle is stably stationary in one of the 16 operating regions divided by a 4×4 grid, is zero.

In flowcharts 1 to 4 of FIG. 4, which will be described later, when the corresponding operating region among the operating regions divided by 4×4 grids changes at predetermined minute intervals, the count value cn
A predetermined value (for example, 4) is set to t, and if it is determined in step 16 that the count l~value cn,t is not zero, the process proceeds to step 17, where the counter I is set.
〜The process of decreasing the value cnt by 1 is performed, so after coming to stop in one operating region in the 4×4 grid, the counter I〜value cnf will be decreased by 1 every time the correction coefficient LMD is proportionally controlled. Therefore, when the Callan I value cnt is zero, it can be regarded as a state in which it remains stably in one region in the 4×4 lattice.

In addition, by determining whether or not the value cnt is zero, it is determined whether learning is to be updated as described later, and learning is not performed at the initial stage when the operating range changes. It's Nishide.

In step 18, it is determined whether or not most of the air-fuel ratio learning correction values corresponding to each segmental operating region of the 4×4 lattice learning map have been learned.

Here, when it is determined in the 4x4 grid learning map 2 that most of the regions have been learned, it is assumed that learning control is basically performed to approximately the base air-fuel ratio or the target air-fuel ratio in the entire operating region. In this case, in the next step 19, it is determined whether or not the object remains continuously in one of the segmented areas in the 4×4 lattice learning map.

In step 19, when it is determined that the vehicle has not stopped continuously in one of the 16 segmented operation areas on the 4x4 grid map, in other words, the corresponding operation on the 4x4 grid map When the area has changed, the process advances to step 20.

In step 20, the difference between the absolute value of the deviation of the latest correction coefficient LMD average value from the target convergence value (=1., O) and the previous absolute value of the deviation is calculated, and the learning value is determined based on this value. Referring to the ΔStress/Response map indicating the degree of inappropriateness, ΔStress is set to increase as the average value variation of the correction coefficient LMD increases.

In other words, since the learning of the 4x4 grid learning map has almost been completed, even if the corresponding driving region on the learning map changes, as long as the learning is progressing accurately, the driving region will remain unchanged. Changes in the base air-fuel ratio can be suppressed to a small level, sufficiently corresponding to differences in the required correction amount due to changes in the air-fuel ratio. Here, if the change in the base air-fuel ratio due to a change in the relevant operating region is large and the air-fuel ratio feedback correction coefficient LMD changes significantly to compensate for this, this indirectly indicates that the learned value is inappropriate. Therefore, Δ stress indicating the degree of inappropriateness of the learned value is set according to the fluctuation level of the correction coefficient LMD.

Furthermore, in step 20, the △S I/Res is integrated,
The integration result is stored as stress.

As will be described later, when this stress exceeds a predetermined value, it is determined that the already learned air-fuel ratio learning correction coefficient is inappropriate, and the learning is restarted from the beginning.

The program shown in the flowchart of FIG. 4 is an air-fuel ratio learning program for each operating region, and is executed at every predetermined minute time (for example, 10 m5).

In step 2I, the P-minute addition is determined, which is a flag that is set to 1 when the air-fuel ratio feedback correction coefficient LIVID is proportionally controlled in flowchart 1 to FIG. When the value is 1, the process proceeds to step 22, where the P-minute addition is reset to zero from 1 to 1, and then various processes by this program are performed, and when it is zero, the program is immediately terminated.

When the P component addition is reset to zero in step 22, in the next step 23, a flag indicating whether the learning correction coefficient KBLRCφ (initial value 1), which is an air-fuel ratio learning correction value common to all operating ranges, has been learned or not. Determine Fφ.

Here, the flag Fφ is zero and the learning correction coefficient KBI
, RCφ has not been learned yet, step 24
Proceed to the maximum and minimum values a, b of the correction coefficient LMD.
It is determined whether the average value (←(a+b)/2) is approximately 1 or not.

When it is not (a + b)/2 or approximately l, the process proceeds to step 26, and the target convergence value Target of the corrected 1-system LMD is determined from (a+b)/2 (in this example, the initial value is 1, 0).
A value obtained by multiplying the value obtained by subtracting the value by a predetermined coefficient X is added to the previous learning correction coefficient KBLRCφ, and the addition result is set as the new learning correction coefficient KBLRCφ.

Also, in step 26, a 4x4 grid map and a 16x
Learning correction coefficient KBLPCI and learning correction coefficient KBLR stored for each segmental operation region of the 16 grid map
Set all initial values of 1 and 0 to C2 to return to the initial state. Therefore, the above learning correction coefficient KBLRC
When learning and updating φ anew, even if 4
Even if learning values are stored in the ×4 grid map and the 16×1.6 grid map, the data is reset and then learning is performed from the learning correction coefficient KBLI'l'Cφ.

When it is determined in step 24 that (a + b)/2 is approximately 1, in step 25 the flag Fφ is set to 1, and the learning correction coefficient KBLRCφ corresponding to the entire operating range is set.
The learning correction coefficient K
It is possible to determine that the air-fuel ratio feedback correction coefficient LMD has converged to approximately 1 as a result of learning and updating B L RCφ.

On the other hand, if it is determined in step 23 that the flag Fφ is 1, the learning correction coefficient K corresponding to the entire operating range
Since this indicates that the learning of BLRCφ has been completed, the air-fuel ratio learning is performed for each region in which the operating region is divided into a plurality of regions based on the basic fuel injection amount Tp and the engine rotational speed N.

First, a 16x16 grid learning map is used to identify the current operating region or the relevant region.

In step 28, a counter value i is used to determine which position of the 16 grids the current basic fuel injection amount Tp is included in.
In the next step 29, it is determined whether or not the counter value i exceeds 15. If it does not exceed 15, in step 30, the basic fuel injection amount Tp corresponding to the count value i is determined. The threshold value Tp [i:l is compared with the most recently calculated basic fuel injection amount Tp.

When it is determined in step 30 that the latest basic fuel injection amount Tp is smaller than the threshold value Tp Ci:l, the process proceeds to step 33 and the count value i at that time is set to the latest basic fuel injection amount Tp or 16 grids. Set ■ as the corresponding area position above. That is, the maximum basic fuel injection amount Tp of each region is set in advance as a threshold value Tp(i), and the latest basic fuel injection amount Tp and the threshold value Tp [:i)
1 at the time when Tp(i)>7'p or the corresponding T
This is set to ■ to indicate the position of the p block.

If it is determined in step 30 that Tp (i)≦Tp, the process proceeds to step 31, where the count value i is incremented by 1, and Tp(i), which is one step larger, is compared with the latest Tp. Make it.

Then, when the count value l is counted up to 16 in step 31, 16 cases 1'-(
In this state, a basic fuel injection amount Tp larger than the initially set maximum value of the basic fuel injection amount Tp range divided into 16 blocks) has been calculated, and at this time, i is set to 15 in step 32, and then step 33 The maximum Tp area of the initialized Tp block and the current Tp
It is assumed that the

Next, for the division into 6 blocks based on the engine speed N,
Similarly to the block determination of the basic fuel injection amount Tp,
The block position that includes the latest engine rotational speed N is determined by the number 1 to value. First, in step 34, the count value k is initially set to zero, and until it is determined in step 35 that this count value 1 exceeds 15, the comparison with the threshold value N(k:] is performed in step 36. and
When N(k)>N for the first time, the count value k is set to K indicating the position of the corresponding N block in step 39, and when N(k)≦N, step 3
At step 7, the counter I~value k is incremented by 1. If the count value 1 exceeds 15, the process proceeds to step 38, where the maximum value 15 is set to the counter I to value k, and the process proceeds to step 39.

In this way, the basic fuel injection amount Tp and the engine rotation speed N
Which operating area of the learning map, which is divided into 256 operating areas of 16x16, includes the current operating condition using parameters CK and I, which are expressed by the block position ■ of Tp and the block position of N, ).

If the corresponding position of the 16×16 grid is found as described above, one operating region in the 4×4 operating region map as shown in FIG. Since it is divided into blocks, it is possible to specify the position to which the current operating condition corresponds in the 4x4 grid learning map based on the above-mentioned I and K.

That is, in step 40, the block number ■ of Tp is divided by 4, and the integer value obtained by rounding down the decimal point of the result is set to A, and in step 41, the block number K of N is similarly set. Divide by 4, and set the resulting integer value, rounded down to the decimal point, to B. As a result, the area position on the 4×4 grid map corresponding to the current operating condition is expressed by the coordinates CB, A).

In the next step 42, using CB, A) indicating the position of the corresponding area on the 4x4 grid map, in order to determine whether or not the corresponding operating area has changed on the 4x4 grid,
The value obtained by multiplying the above value by 16 is added to B, and the result is set to AB.

Then, in step 43, A
By comparing BoLI) and the latest AB, 4×
It is determined on the 4-lattice map whether or not the current area is the same as the previous area. A, B-7! :ABot,
o, and if the corresponding area on the 4×4 lattice map is different from the previous one, a predetermined value (for example, 4) is set to the count value cnt in step 44.

In step 45, AB calculated in step 42 this time is set in ABoLD as the previous value for the next determination in step 43.

In step 46, [B,
A flag F (B, A:] indicating whether or not air-fuel ratio learning has been completed is determined based on the current operating conditions or operating range that is specified using A) as the coordinate, and this flag F (B,
A,) is zero and the current operating condition is included 4×
If learning has not been completed in one operating area of the 4-grid map, the process advances to step 47.

In step 47, it is determined whether or not the counter I-value cnt is zero, and if it is not zero and there is a change in the corresponding area in the 4x4 grid map, the program is terminated and the count value cnt is zero. Step 4 is performed only when the vehicle is stably stopped in the relevant operating range.
Proceed to step 8.

In step 48, the average value (a + 11))/2 of the maximum and minimum values a and b of the air-fuel ratio feedback correction coefficient LMD sampled in the flowchart of FIG. 3, that is, the center value of the correction coefficient LMD is The progress of learning is determined depending on whether the correction coefficient LMD is near the initial value (21), which is the target convergence value, and if it is not recognized as approximately 1 and learning has not been completed, the process proceeds to step 50.

In step 50, the current C
The value obtained by subtracting the target convergence value Target (1.0 in this example) from the average value of the maximum and minimum values a and b for the learning correction coefficient KBLRCI stored corresponding to the areas B, A,) is multiplied by a predetermined coefficient

In step 48, it is determined that (a+b)/2 is approximately 1. This means that learning in the operating region of the 4×4 grid map that includes the current operating conditions has been completed, so step 49 Then, flag F [:B, A) is set to 1, so that it is determined that learning has been completed for the area where the flag F (B, A) is a force cylinder.

During learning in the region [:B, A) on such a 4x4 grid map, in a finer 16x16 grid map, the 4x4-16 area included in the above [:B, A)]
As for the learning correction coefficient KBLRC2 in each region, all are reset to the initial value 1.0 in step 51.

In this way, when there is a region in which learning has not yet been completed in the 4x4 grid map, when the operation becomes stable in that region, (
The predetermined percentage of the deviation from the target value 'rarget of a+b)/2 is calculated using the previously stored learning correction coefficient KBL.
By adding and updating the RCI, the learning correction coefficient KBLR is used instead of the air-fuel ratio feedback correction coefficient LMD.
It is assumed that the target air-fuel ratio is obtained through correction by CI, and that the learning for that operating region is completed when the air-fuel ratio feedback correction coefficient LMD substantially converges to the initial value 1, which is the target convergence value.

On the other hand, in step 46, the flag F (B, A,) is set to 1.
If it is determined that the learned correction coefficient KBLRCI is stored in the current operating area of the 4x4 grid map, then the learning correction coefficient KBLPCI or the stored learning correction coefficient KBLPCI on the current 4x4 grid map is stored. Operating area [:B,
A) is further subdivided into 16 regions to move to learning in the corresponding region of the 16X]6 lattice learning map.

Step 52 is the average value of the correction coefficient LMD (a
10b)/2, or approximately matches the target convergence value of 1. If it is in the learning state, the process advances to step 53.

In step 53, the target convergence value Ta is calculated from (a + b)/2.
The value obtained by subtracting rget (1.0 in this example) and multiplying by a predetermined coefficient The learning correction coefficient KBLRC2 stored up to
(K, T:], and use this addition result as a new correction coefficient KBLRC2 in the relevant operating region (K, I).
Update settings are made as [, I<, I).

On the other hand, if it is determined in step 52 that (a+b)/2, which is the average value of the correction coefficient LMD, substantially coincides with 1, which is the target convergence value Target, the process proceeds to step 54;
I is placed under the flag F(K, I) so that it can be determined that the learning of the operating region (K, I:] that includes the current operating conditions of the 16×1.6 grid map has been completed.

Then, from step 55 onwards, it is determined that the current learning has been completed, and the corresponding flag FF (I (, 1) is set to 1).
Based on I), if there is an operation area adjacent to this area (K, I) for which learning has not been completed (see Figure 10), the current operation area (K, I) is added to that operation area. Control is performed to update and store the same value as the learning correction coefficient KBLRC2 stored correspondingly.

In step 55, the values obtained by subtracting 1 from CK, I], which indicate the position of the area containing the current operating condition, in the 16x16 grid map are set to m and n, and in the next step 56, m=+2 Determine whether or not.

When the process advances from step 55 to step 56, the determination in step 56 is NO, and the process proceeds to step 57 to complete the learning of one operating region of the 1, 6×16 grid indicated by (m, n). It is determined whether the flag FF(m, n) is l or zero.

Here, if the flag FF (m, n) is zero and learning has not been completed, the process advances to step 58.

In this step 58, the area address (m, n) on the 16XI6 grid is converted to the area address [m/n] on the 4x4 grid.
4, n/4:l, and this is the area CB on the 4x4 grid map that is currently determined to be applicable.
.

A].

That is, (K, I) is an area included in CB, A), but the area surrounding (K, I) is another area adjacent to (B, A:] on the 4 × 4 case r map. This is because it may be included in the area, and when the area is included in the same CB, A,), ((m/ 4. n/ 4-) = CB, A
)), the process proceeds to step 59, and the learning correction coefficient KBLRC corresponding to the [K, I) area determined to have been learned this time is determined.
2 is used as the (m, n) area learning value.

On the other hand, in step 58, (K, I) is adjacent to (m).

n] is determined to be included in a different region in the 4×4 lattice map, the process proceeds to step 6o, and the learning correction coefficient K calculated by the following formula is applied to the region (m, n:l).
Store BLRC2.

KBLRC2(m, nil ← KBLRCI (B, A) 10KBLRC2(K,
[1-KBLRCI (m/4.n/4) The formula for calculating the above KBLRC2 (m, n) is
Since [K, T) and [m, n] are adjacent areas on the 16x1.6 grid, the final correction request is based on the assumption that they are similar. The learning correction coefficient KBL of the 4×4 grid map that includes
Since the RCI is different, each KBLRCI is different.
(B, A,), KBLRCl, (rn
/4, n/4] is set to be approximated by the following formula.

KBLRCI (B, A) +KBLRC2 (K,
I) =KBLRCI Cm/4. n/4)
+KBLRC2(m, n) as above (
m, n) When the area has been learned, the learned value is not updated, and when the area has not been learned, the KBL
KBLRC2(m, I) based on RC2[:ni, I)
n, ), step 61 increments m by 1 and returns to step 56, where m =
Immediately, n is kept constant and m is moved in the +1 range centered on K until K + 2 is reached, and learned/unlearned is determined for each driving region.

When it is determined in step 56 that m- is +2 as a result of the 1-up processing of m in step 61, the process proceeds to step 62, and it is determined whether n=I+2, and n≠1+2. If so, m is set to -1 again in step 63, and n is incremented by 1 in step 64, after which the process proceeds to step 57.

Therefore, initially let n=l-1 and m is centered at K±
Next, we set n==I and moved m within a range of ±1 around K, and then set n=1+1 and discriminated adjacent areas. As a result, when the eight operating regions (see Figure 10) surrounding CK, I) have not been learned, the learning correction coefficient KBLRC2(K, I)
The value based on the learning correction coefficient KBLRC2 for that operating region
(It is stored as m, nl.

In this way, if the learning results of the learned area are applied to the surrounding unlearned areas, the learning map for each driving area can be subdivided like a 6x16 grid learning map. Even if there are only a few opportunities, it is possible to prevent large differences in air-fuel ratio controllability from occurring between operating ranges.

When it is determined in step 62 that n=Imo2, it means that the determination processing for all eight operating regions surrounding [K, T) has been completed, and at this time, in step 53-
\Proceeding, the learning correction coefficient K B t, RC2 which is determined to have already been learned in the current area (K, I)
The learning accuracy is further improved by updating the learning.

In this way, in this embodiment, first, the learning correction coefficient KBLRCφ corresponding to all driving regions is learned, and then learning is performed for each driving region divided by a 4×4 grid learning map. For areas that have already been learned using a ×4 grid learning map, that area is further divided into 4 × 4 grids for learning, so learning can progress from large driving areas to small driving areas. The convergence of the air-fuel ratio is ensured by learning in a large operating range, and as the learning progresses, more detailed learning is performed for each operating range, so the difference in the required correction value due to the difference in operating range is Can respond with high precision.

The three learning correction coefficients 1 (B
Setting of the final air-fuel ratio learning correction coefficient KB LRC based on 1, RCφ, KBLRCl, KBI, RC, 2 is performed according to flowcharts 1 to 7 in FIG.

Flowchart 1 in FIG. 7 is processed as a background job. First, in step 71, the learning correction coefficient KBLRCI stored in the area CB, A) of the 4×4 grid map is read out, and Next step 72 is 16X], area of 6 grid map [K, I:
The learning correction coefficient KBLRC2 stored in l is read out. In addition, from flowchart 1 to Bx418 and Kx16-1 shown in the flowchart 1. -1 is for converting the address indicating each grid position into an address on the memory.

In step 73, the final learning correction coefficient KBLRC is set as (KBLRCφ+KBLRCl 10 KBLRC, 2-2, 0→KBLRC).

The learning correction coefficient KBLRC set in flowcharts 1 to 1 of FIG. 7 above is used to calculate and set the fuel injection amount Ti in the program shown in flowchart 1 to 1 of FIG. 5.

The program shown in flowchart I~ in FIG. 5 is executed every predetermined minute time (for example, 10m5),
First, in step 81, the engine rotation speed N calculated based on the intake air flow rate Q detected by the air flow meter 13 and the detection signal from the crank angle sensor 14 is input.

Therefore, in the next step 82, the basic fuel injection amount T corresponding to the intake air flow rate Q per unit rotation is determined based on the intake air flow rate Q and the engine rotational speed N input in step 81.
p (←KXQ/N; is a constant) is calculated.

In the next step 83, step 82! The basic fuel injection amount Tp calculated by iM is subjected to various corrections to calculate the final fuel injection amount (fuel supply amount) TI.

Here, the correction value used for correcting the basic fuel injection amount Tp is the learning correction coefficient KBLRC, which is learned and set for each area according to flowchart 1 in FIG. 4 and finally set according to the flowchart in FIG. Various correction coefficients are set including the air-fuel ratio fee I/back correction coefficient LMD calculated according to Char 1, the basic correction coefficient based on the cooling water temperature Tw detected by the water temperature sensor] 5, the post-start increase correction coefficient, etc. C0EF is a correction numerator s for correcting changes in the effective injection time of the fuel injection valve 6 due to changes in battery voltage, Ti=TpXLMDXKBLRc XC0E
The final fuel injection amount Ti is updated at predetermined time intervals as F1Ts.

When the control unit 12 reaches a predetermined fuel injection timing, the control unit 12 transmits a drive pulse signal of "pulse 1 corresponding to the latest calculated fuel injection amount T1" to the fuel injection valve according to the program shown in flowchart 1 of FIG. 6 to control the amount of fuel supplied to the engine 1.

Furthermore, in step 84, tm for counting the rich or lean control time in flowchart 1 of FIG. 3 is incremented by 1.

In addition, the program shown in flowchart l~ in Figure 6 is as follows:
This is a program that performs processing based on "I/Res" indicating the degree of inappropriateness of the learning correction value sampled according to the flowchart of FIG. 3, and is executed as a background job (BGJ).

In step 91, the stress (degree of air-fuel ratio deviation) accumulated in step 20 of the flowchart in FIG. It is determined whether the degree of deviation is within a predetermined range.

Here, when the stress exceeds a predetermined value, it is determined that although learning has almost completed, the learning result is inappropriate and an air-fuel ratio deviation has occurred, and learning is performed again (learning repetition). The process advances to step 92 in order to do so.

In step 92, a flag Fφ is set for determining whether or not air-fuel ratio learning for each operating region has been completed.

FI: 0. 0) ~FC3,3), FFC0
, 0) to FF (1, 6, 16) are all reset to zero so that learning is performed from the learning correction coefficient KBLRCφ corresponding to all operating ranges, and the stress is reset to zero.

In this way, if the degree of deviation (stress) of the air-fuel ratio feedback correction coefficient LMD from the reference value becomes larger than a predetermined value, relearning can be performed to prevent accidents such as preventing holes from forming in the intake system. When the air-fuel ratio suddenly changes, learning for each large operating region is performed again, so the air-fuel ratio can be quickly converged.

Next, electronically controlled fuel injection is performed based on the sum sum SUML of the lean control amount and the sum sum SUMR of the rich control amount within a predetermined period (in this example, 5 minutes as described later) determined in the flowchart of FIG. The self-diagnosis of the device will be explained according to the flowchart of FIG.

The self-diagnosis program shown in the flowchart of Figure 8 is as follows:
It is executed at predetermined time intervals (for example, 5 minutes), and first, in step 101, the sum S of the enrichment control amounts set in steps 7 of flowchart 1 to 1 of FIG.
The UMR is compared with the slice level SLI, which is set in advance for determining the enrichment control amount.

Here, when the sum sum SUMR of the enrichment control amount exceeds the slice level SLI, the correction coefficient LMD is increased or increased for a longer time than usual in order to enrich the air-fuel ratio within a predetermined period. Show that.

In this case, the air-fuel ratio tends to deviate significantly in the lean direction from the target air-fuel ratio due to some kind of malfunction, such as component deterioration/failure, manufacturing variations in parts, or a state in which air-fuel ratio learning has not progressed sufficiently. Therefore, it is assumed that the large enrichment control described above became necessary.
Due to the trend toward leaner air-fuel ratios, the exhaust characteristics are
It is estimated that it has increased by 1m degree.

Therefore, when it is determined that SUMR>SLI, the process proceeds to step 102, and it is determined that the NOx concentration in the exhaust gas tends to increase due to the deterioration of the air-fuel ratio control ability where the air-fuel ratio deviates significantly to the lean side. For example, the driver is warned by a display device installed near the driver's seat.

On the other hand, in step 101, the sum sum SUMR of the enrichment control amount
If it is determined that the slice level is below the slice level SL1, it is assumed that at least an abnormally large lean change has not occurred, and the process jumps to step 102 and proceeds to step 103.

In step 103, in the same way as step 101, the total sum of lean control amounts SUML set in step 13 to flowchart 1 in FIG. Level SL
Compare with 2.

Here, when the sum of the lean control amounts S U M L exceeds the slice level SL2, the correction coefficient LMD is set to the decreasing side larger than usual or for a long time in order to make the air-fuel ratio lean within a predetermined period. ■Indicates that it was done. In this case, the air-fuel ratio tends to deviate significantly toward richer than the target air-fuel ratio due to some kind of malfunction, such as component deterioration/failure, manufacturing variations in parts, or a state in which air-fuel ratio learning has not progressed sufficiently. It is presumed that the above-mentioned lean control has become necessary due to this, and it is presumed that the CO and HC concentrations are increasing as exhaust characteristics due to the tendency of the air-fuel ratio to become richer.

Therefore, when it is determined that SUML>SL2, the process proceeds to step 104, and J, It:
For example, a display device installed near the driver's seat warns the driver that the O and HC concentrations tend to increase.

On the other hand, in step 103, the total sum of lean control amounts SUM
If it is determined that the air-fuel ratio is lower than the slice level SL2, it is assumed that no malfunction has occurred that would cause the air-fuel ratio to shift significantly toward the rich side, and step 10
4 and proceed to step 105.

As mentioned above, the sum of rich or lean control amounts SU
By determining whether or not MR and SUML exceed a predetermined slice level, it is possible to monitor changes in exhaust characteristics (see Figure 11) due to generation of base air-fuel ratio differences, especially when operating conditions change. .

In the next step 105, the sum of enrichment control amounts SUM
The average value SUM of R and the sum sum SUML of the lean control amount is calculated.

Then, in step 106, the average value SUM is compared with a preset slice level SL3, and the average value SUM is compared with a preset slice level SL3.
When UM is less than slice level SL3, the change in correction coefficient LMD is one cycle or abnormally small;
In this case as well, it is assumed that the air-fuel ratio control condition is deteriorated due to an abnormality in the correction state by the correction coefficient LMD. However, in this case, it is not possible to distinguish whether the actual air-fuel ratio tends to shift towards the rich side or the lean side due to such an abnormality, so in reality, NOx or CO
If it is estimated that the concentration of one of O and IC is increasing, step 107 indicates that the concentration of NOx, Co,
Displays/warns abnormalities in HC concentration.

For example, if only one specific cylinder among a plurality of cylinders becomes lean due to clogging of the fuel injection valve, the output of the oxygen sensor 16 or the exhaust gas of the lean cylinder is changed as shown in FIG. If there is a temporary decrease when detected, this temporary lean is considered to be a reversal of the air-fuel ratio, and proportional control is applied, so that the control cycle of the correction coefficient LMD is normal. Since the average value SUM is shorter than the average value SUM, the average value SUM becomes smaller.

As shown in -4-, when the air-fuel ratio of one specific cylinder is made uniform, the average air-fuel ratio obtained as a result of the air-fuel ratio feedback correction control also becomes leaner, as shown in FIG. If only the air-fuel ratio of one cylinder is enriched, the average air-fuel ratio obtained as a result of the air-fuel ratio feedback correction control will also become enriched. Therefore, when the average value SUM is less than the slice level SL3, it is estimated that the air-fuel ratio of only a specific cylinder is drifting towards the rich or lean side, but since it is only possible to specify the direction of the shift, here, It is designed to display abnormalities in NOx, CO, and HC concentrations.

As mentioned above, when only the air-fuel ratio of a specific cylinder deviates from the target air-fuel ratio, the air-fuel ratio feedback correction coefficient LM
Since it is difficult to diagnose only from the change "1" in D, as in this embodiment, the air-fuel ratio control oil amount is determined based on the parameters of both the small change in the air-fuel ratio feedback correction coefficient LMD and the control time. It is preferable to try to capture it.

As described above, when an air-fuel ratio deviation due to an abnormality in the fuel supply control system is diagnosed based on the sum SUMR of the enrichment control amount and the sum SUML of the lean control fall amount, in the next step 108, the sum SUMR ,SUM
Reset L to zero, respectively, so that the air-fuel ratio control amount data within the next predetermined time (within the execution period of flowchart 1 in FIG. 8) are newly integrated into the sums SUMR and SUML.

In this way, in this embodiment, self-diagnosis is performed based on the movement of the air-fuel ratio feedback correction coefficient LMD, so there is no need to wait for the progress of learning as in the case of diagnosis based on the learning correction coefficient KBLRC. Moreover, it is possible to perform a self-diagnosis of the fuel supply control system that is correlated with the exhaust characteristics, and it is possible to warn against driving in situations where the exhaust characteristics have deteriorated.

In this embodiment, the sum sum SUMR of enrichment control amounts as a value representing the air-fuel ratio feedback correction coefficient LMD (air-fuel ratio feedback control amount) within a predetermined period is
and the sum sum SUML of the lean control amount is determined by the correction coefficient I'lE determined by the basic fuel injection amount Tp and the engine rotation speed N.
Alternatively, the slice level may be corrected depending on the operating conditions.

However, the predetermined period for monitoring the movement of the correction coefficient LMD is 5
It is desirable to take a relatively long time of about 10 minutes to 10 minutes as a value that corresponds to operating conditions including steady operation and transient operation, and in this case, it is difficult to change the slice level appropriately depending on the operating conditions. Therefore, it is preferable to correct the yarn number LMD fluctuation data based on the operating conditions as in this embodiment.

In this embodiment, the slice level SL1. ．． SL2 is installed to diagnose abnormalities in the concentration of exhaust components, such as NOx and C○.

It is possible to diagnose HC and HC separately, or a common slice level may be provided for rich side and lean side for discrimination, or a simple air-fuel ratio deviation may be warned as a diagnosis result.

Furthermore, a configuration may be adopted in which the data of the change in the air-fuel ratio feedback correction coefficient LMD and the rich/lean control time are individually sampled, and the self-diagnosis is performed individually based on these data.

Further, in this embodiment, the data of the air-fuel ratio control amount within a predetermined period may be integrated, or the average value of the air-fuel ratio control amount within a predetermined period may be calculated.

<Effects of the Invention> As explained in section 2 below, according to the present invention, the air-fuel ratio control state can be diagnosed based on the air-fuel ratio feedback control amount by correlating it with the exhaust characteristics, so that the air-fuel ratio control amount due to component deterioration or failure can be diagnosed. It becomes possible to monitor changes in exhaust characteristics due to fluctuations in the base air-fuel ratio due to deterioration or changes in operating conditions, and has the effect of making it possible to successively monitor deterioration of exhaust characteristics such as exceeding regulation values, for example. .

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the invention, and Figs. , FIG. 9 and FIG. 10 are diagrams showing the state of the learning map in the same two embodiments, and FIG. 11 is a time chart showing the movement of the feedback correction coefficient when a base air-fuel ratio difference occurs due to a change in operating conditions. , 12th
The figure shows time chart 1 showing the state of air-fuel ratio feedback control when only the air-fuel ratio of one specific cylinder among multiple cylinders becomes lean, and FIG. 14 to 17 are diagrams showing the degree of variation in the average air-fuel ratio when the air-fuel ratio changes, respectively, for explaining problems in self-diagnosis based on the average value of the air-fuel ratio learning correction value. 1... Engine 6... Fuel injection valve 12... Control l-. - Unit I-13... Air flow meter 14...
Crank angle sensor 15... Water temperature sensor 16.
...Oxygen sensor patent applicant Fujio Sasashima, agent and patent attorney for Japan Electronics Co., Ltd. Figure 6 Figure 10 □ and Figure 11

Claims (3)

[Claims] (1) An air-fuel ratio detecting means for detecting the air-fuel ratio of the air-fuel mixture taken into the engine; and comparing the actual air-fuel ratio detected by the air-fuel ratio detecting means with a target air-fuel ratio to determine the actual air-fuel ratio as the target air-fuel ratio. an air-fuel ratio feedback control amount setting means for setting an air-fuel ratio feedback control amount for correcting the air-fuel ratio of the engine intake mixture so as to approach the air-fuel ratio; and an air-fuel ratio feedback control amount set by the air-fuel ratio feedback control amount setting means. an air-fuel ratio increase/decrease correction means for controlling a controlled object related to the air-fuel ratio of an engine intake air-fuel mixture based on the air-fuel ratio to increase/decrease the air-fuel ratio; Diagnosing the air-fuel ratio control state in the fuel supply control device based on at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount set by the amount setting means and the control time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount. 1. A self-diagnosis device for a fuel supply control device for an internal combustion engine, comprising an air-fuel ratio control diagnosis means. (2) The air-fuel ratio control diagnostic means detects a representative value within a predetermined period of at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount and the control time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount; 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein the fuel supply control device for an internal combustion engine is configured to diagnose the air-fuel ratio control state in the fuel supply control device by comparing the slice level with a preset slice level for each operating condition. Self-diagnosis device. (3) The air-fuel ratio control diagnosis means determines a representative value within a predetermined period of at least one of the magnitude of the increase/decrease change in the air-fuel ratio feedback control amount and the time for increasing/decreasing the air-fuel ratio by the air-fuel ratio feedback control amount; The air-fuel ratio control state in the fuel supply control device is diagnosed by comparing slice levels individually set on the air-fuel ratio increase control side and the air-fuel ratio decrease control side based on the air-fuel ratio feedback control amount. Claim 1
A self-diagnosis device in the fuel supply control device for the internal combustion engine described above.