JPS6338637A - Air-fuel ratio control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent a poor exhaust emission at the initial stage of transient, when the target air-fuel is leaner than the basic air-fuel ratio, by correcting the transient correction quantity based on the balanced quantity of adhesion so as to be reduced. CONSTITUTION:The basic fuel injection quantity TP corresponding to operating conditions is calculated by a calculating means 1, and this is corrected by correction calculating means 6 using a transient correction quantity. A transient correction quantity calculating means 2 is comprised of a means 3 which calculates the balanced quantity of adhesion in correspondence to operating conditions, a means 4 which calculates the adhering velocity as a transient correction quantity on the basis of the deviation between the balanced quantity of adhesion and the calculated value of adhering quantity which changes with the first-order lag to this balanced quantity of adhesion, and a means 5 which calculates the quantity of adhesion of this time. And, when the target air-fuel ratio is discriminated by a discriminating means 7 to be leaner than the basic air-fuel ratio, the transient correction quantity is corrected by a correction calculating means 8 so as to be reduced. Thus, an overcorrection is prevented, and a poor exhaust emisson can be prevented.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an air-fuel north side 81 device for an internal combustion engine.

(Prior Art) Electronically controlled fuel injection engines are actually widely adopted due to their high fuel metering accuracy, and when controlling the injection amount supplied from the injection valve to the engine intake system, the engine load (for example, intake air Basic fuel injection amount (basic pulse width) T p("K-Qa/N,
However, K is a constant. ) is corrected according to other operating variables.The injection amount (injection pulse width) Ti is calculated based on the following equation (1) (for example, 1985 1177 (
(Refer to "Automatic Single Ball T" Vol. 34, No. 11, No. 28'FA, etc. published by Railway Japan Co., Ltd.).

Ti=TpXCOEFXLMBDA+Ts...(1
) However, C0EF: Sum of various correction coefficients LAMBDA:
Air-fuel ratio correction coefficient Ts: Invalid pulse width.

(Problems to be Solved by the Invention) However, in a device (hereinafter referred to as an RSPR device) in which one or more fuel injection valves are attached to a gathering part of the intake passage far from the engine cylinder, Before some of the injected fuel reaches the shilling, the amount of fuel that adheres to the intake pipe or the inner wall of the intake boat, or that is floating in the intake pipe without being inhaled (this amount of fuel is hereinafter referred to as the "adhesion amount"). ) occurs as a fuel delay during a transient period, which greatly affects the accuracy of air-fuel ratio control.

Therefore, based on the amount of adhering fuel in the intake system under steady-state operating conditions (hereinafter, this adhering amount is referred to as the "equilibrium adhering amount") and the calculated value of the adhering amount that changes with a first-order lag with respect to this equilibrium adhering amount. The transient correction amount (KATH
The applicant previously proposed a device that controls the target air-fuel ratio by correcting the basic injection amount (basic fuel injection amount according to the operating condition) (TI) at O8). (This is referred to as the "earlier proposal.")

However, when conducting experiments, it was found that as the target air-fuel ratio determined depending on the driving state became leaner, the exhaust emission became poorer, especially in the early stages of acceleration. This is because the leaner the target air-fuel ratio, the less adhesion of intake fuel, so the air-fuel ratio (
This is called the "basic air-fuel ratio." ), the transient correction amount would have to be reduced by the amount corresponding to the amount that the target 2 fuel ratio is leaner than the basic air-fuel ratio, but this would result in overestimation, resulting in over-correction. This is because it has become.

This is shown in Figure 10, which shows the case where other conditions are the same and only the target air-fuel ratio is different (the stoichiometric air-fuel ratio A/
This is a waveform diagram of the transient correction amount for the case of F+s and the case of the leaner air-fuel ratio A/F21), and if A/F15 (solid line) is now matched as the basic air-fuel ratio, the target 2
Q ratio is A/F.

If it is 5, there will be no excess or deficiency in the amount of transient correction. However, when the target air-fuel ratio becomes A/F2+ (dashed line), the amount shown by the broken line is sufficient, but the fuel supply is changed so that the amount shown by the solid line is secured as the transient correction amount, so these characteristics There will be an oversupply of fuel by an amount corresponding to the area surrounded by the curves.

Therefore, in order to eliminate such excessive correction of the transient correction amount, the transient correction amount relative to the basic air-fuel ratio may be reduced as the target air-fuel ratio becomes leaner than the basic air-fuel ratio.

This invention is as follows. This was done by focusing on α, and it is determined whether or not the target air-fuel ratio is leaner than the basic air-fuel ratio, and when it is determined that it is lean, the transient correction amount for the basic air-fuel ratio is reduced. It is an object of the present invention to provide an air-fuel ratio control device.

(Means for solving problems) The present invention is constructed as shown in FIG.

In other words, the above proposal also includes a means 1 for calculating the basic fuel injection amount Tp according to the operating condition, an equilibrium adhesion amount of intake system fuel for the basic air-fuel ratio, and a means for calculating the equilibrium adhesion amount. Means 2 calculates a correction amount during a transient period based on the deviation from the calculated value of the adhesion amount that changes with a first-order lag, and means 6 calculates a correction calculation for the basic injection amount Tp using this transient correction amount. .

In the present invention, in the above air-fuel ratio control device, means 7 for determining whether or not the target air-fuel ratio determined depending on the operating state is leaner than the basic air-fuel ratio described in 1ijf;
A means 8 is additionally provided for reducing the transient correction amount for the basic air-fuel ratio when it is determined that the fuel is lean based on the determination result.

Incidentally, the transient correction amount calculation means 2 is configured to calculate, for example, the basic 'g'.
! Means 3 calculates the equilibrium adhesion amount with respect to the fuel ratio according to the operating state, and calculates the amount of adhesion per unit period (for example, 1 means 4 for calculating the adhesion amount (per injection) (this adhesion amount is hereinafter referred to as "adhesion speed"); and means 5 for calculating the current adhesion amount by adding this adhesion speed to the calculated adhesion amount. It is composed of.

(Function) When fi is established in this way, when the target air-fuel ratio becomes leaner than the basic air-fuel ratio, this is determined and the transient correction amount is corrected to be reduced. In other words, the leaner the target air-fuel ratio is, the smaller the calculated transient correction amount is, so it matches well with the actual intake system fuel adhesion state, thereby preventing defects in #air-emissions during the transient transition. Can be done.

This will be explained below using examples.

(Example) In FIG. 2, one fuel injection valve 24 that serves all cylinders is provided in the intake passage 22 upstream of the intake throttle valve 21 (SPI device).
81 mechanical configuration when the present invention is applied to an engine in which the throttle valve opening α (also referred to as TVO) is used as the engine load signal instead of the air amount in order to simplify the device.

Therefore, in this example, the injection pulse width is controlled using α and N as basic variables (hereinafter, this will be referred to as the α-N method). Therefore, an air amount sensor is not provided, but a throttle valve opening sensor 25 is provided instead. In addition, in the passage 23 that bypasses the throttle valve 21, two idle-up solenoid valves (referred to as S■) 26 and 27 are provided in parallel in order to enhance control at the time of starting.9. On the other hand, a swarf troll valve 28 is provided on the intake boat.

Note that the engine speed N is determined by a crank angle sensor 32 built into the distributor 31, the cooling water temperature T+u is determined by a water temperature sensor 33, and an oxygen sensor 34 is provided as a sensor for detecting the actual air-to-air ratio, which is different from the conventional device. However, these crank angle signals (reference signal and angle signal),
The water temperature signal and the actual air-fuel ratio signal are inputted to the control unit 35 together with the above-described valve opening signal, and the optimum fuel injection pulse width Ti is calculated in the control unit 35 based on these numbers.

For the calculation details of the injection pulse width Ti for dogs, see f53.
Figure (consisting of the same figure (A) to the same figure (C). The same applies hereinafter.

) to FIG. 7, the parts relating to the present invention will be explained first, and then the system as a whole will be outlined. In other words, the control contents shown in these figures constitute one air-fuel ratio control system as a whole, and the breakdown of these is as follows: Figure 3 is the main routine for calculating the injection pulse width, and Figures 4 to 7 are the main routine for calculating the injection pulse width. Variables used in the main routine (transient correction amount KA
T)-IOS, feedback correction amount LAMBD
A, target air-fuel ratio TFBYA, intake air temperature correction coefficient KTA). The numbers in the figure represent processing numbers. Incidentally, such control can be easily performed by using a control unit (35) using a microcomputer. In this case, the calculation of each variable is as shown in the table below: , when it is determined that the air-fuel ratio is lean, transient correction 1 is applied to the basic air-fuel ratio.
The amount of transient correction KAT is
In the routine for calculating HO3 (FIG. 4), steps 132 to 134, 105, and 106 are provided.

That is, when it is determined that the target air-fuel ratio is leaner than the basic air-fuel ratio, the air-fuel ratio correction factor G HF F B Y A
Calculate this air-fuel ratio correction factor G HF F B Y A
By multiplying the adhesion speed VMF, the final transient correction amount K A T HOS (- is determined (step 132
,133.105,106)a KATHOS=VMFXGHFFBYA...(7^-
Δ) Here, in this example, the transient correction amount is determined by clock synchronization (injection synchronization), so the transient correction amount per unit cycle (per injection) is the standard, and the transient correction amount per injection is This is the adhesion speed VMF.

In addition, since the air-fuel ratio correction factor GI ``F B Y A i:i < a was introduced to reduce the transient correction amount, it can be simply a constant of 1.0 or less, but in this example, Calculation is performed according to the target air-fuel ratio (TF B Y A ) so that a transient correction amount corresponding to the target air-fuel ratio at that time is obtained (step 133).As a result, the transient correction amount for the basic air-fuel ratio is The corresponding VMF is the correction factor GHFFBYA
The weight loss will be corrected.

Note that the deceleration correction factor GHFQ CY L is a correction term during deceleration (step 105), and is not directly related to the present invention.

Next, the operation of this embodiment when the target air-fuel ratio is on the lean side than the basic air-fuel ratio will be explained with reference to FIG. This is a characteristic diagram of the transient correction amount required when changing from to full throttle, where the broken line shows the characteristics for the basic air-fuel ratio, and the solid line shows the characteristics for the 2-fuel ratio that is leaner than the basic air-fuel ratio. .

As is clear from the figure, the amount of transient correction required for an air-fuel ratio leaner than the basic air-fuel ratio is smaller than for the basic air-fuel ratio.

In response to such transient correction amount characteristics, in the previous proposal, even if the target air-fuel ratio becomes leaner than the basic air-fuel ratio,
Since the transient correction amount for the basic air-fuel ratio was supplied, the supplement 'f' was excessive.

On the other hand, in this embodiment, when the I2 air-fuel ratio becomes leaner than the basic air-fuel ratio, the value GHFF is smaller than 1.0.
BYA is multiplied (by this, the transient correction amount is reduced by an amount corresponding to the leanness of the target air-fuel ratio. As a result, the small amount of adhesion required for the target air-fuel ratio at that time is reduced by the amount of adsorption). The fuel supply is organized so that it exists in the
Defects in exhaust emissions at the beginning of acceleration can be prevented.

Note that if the target air-fuel ratio is equal to or higher than the basic air-fuel ratio, no correction is made (steps 1.32 and 1).
34).

Furthermore, in this embodiment, −C is the air-fuel ratio correction factor G r−(
Although FFBYA is determined as a function of TFBYA, in a lean burn system where the target air-fuel ratio is uniformly set to a constant value (for example, 21), it is possible to set FFBYA as a constant of 1 or less in step 133. Not even.

Next, to outline the entire system, the routine in Figure 3 is the part that finally calculates the injection pulse @Ti using the formula (4) below, and corresponds to the functions of means 1 and 6 in Figure 1. do.

Here, in the SPI device, the air flowing into the Schilling '1c
There is a difference in that QCYL and the air ff1QA+NJ passing through the injection valve do not necessarily match, and there is a supply delay for the fuel injected from the injection valve to reach the shilling, so in this system, these two ．． has been considered. However, these are calculated independently for each (QAINJ is calculated for the air amount, and the transient correction amount KATHO3 is calculated for the fuel delay). This is to simplify the concept and clarify whether the control error is due to an air amount metering error or a fuel delay. This greatly improves the accuracy during setting. Furthermore, changes over time after setting and differences in fuel properties can also cause accuracy to decrease, so
It has a learning function.

Expressing this mathematically, the effective pulse width Te is calculated by the following formula (4
) (step 70). Note that, assuming that the invalid pulse width is Ts, the sum with Te is T i (= T e + Ts
) (step 69.70).

Te=(TpXKBLRC+KATHO8XKBTLR
C) XLAMBDA...(4) However, Tp: Basic pulse width K A T HOS: Transient correction amount L A M B D A: Air-fuel ratio correction coefficient KBLRC
: Basic injection amount learning correction coefficient K B T L RC: Fuel delay learning correction coefficient.

Here, Tp is used as the basic pulse width, but its content is different from the L-Jetronitter method and is expressed by the following formula (5).
It is calculated by.

Tp=QAI N J G XTFBYAXK-(5)
However, QAINJG: Injection valve air amount<rllg)T
FBYA: To the target air-fuel ratio: Constant based on injection characteristics (Injection 5/fil g
).

First, the air amount QAINJ in the injection valve section is difficult to directly obtain in this embodiment, which does not have an air amount sensor, so it is obtained based on QCYL. In other words, QAINJ is Qcy, and its variation dQ c Y
Considering that it can be approximately obtained from the following formula (3) from L / dt, the following formula group (6A
) to (6F). For convenience of explanation below, the subscript "-1" means the value calculated previously.
is attached to the symbol.

QA I N J G = QA I N J CXKT
A =・(6Δ)QAINJ6=QCYLXVCYL +DCM...(6B) QCYL=QllXK2 +QCYL-+ X(2 to 1-)...(6C) QH=QH[l
DCM=(QcyL QCYL-1)
KTA: KTA OX KTA Q
CY L...(6F) Just I7, QAINJG: Injection valve air amount/cylinder (rnFl) QA+nJc: Injection valve air amount/sylling (cc) Air 1 to QCYL Nijiring/Schilling volume (%) VCYL Nijiring volume (CC) DCM: Air change amount in manifold (ce) KTA: Intake temperature correction coefficient (+ng/cc) QH: Equilibrium air amount/Schilling volume (%) K2: QCYL change rate/calculation Quo: Linearized air amount/Schilling Volume (%) KFLAT Nearat air-fuel ratio coefficient (%) KMAN IO
: Manifold coefficient Tref: Ref signal period (μ5) KTAO: Basic intake temperature correction coefficient (+ag/cc) K T
A Q c Y L: Load correction rate of intake temperature correction (%
).

These second groups (68) to (6F) have become complicated due to various corrections and standardizations (converted to per shilling, per shilling volume, etc.), but basically they are ,
QAINJC is determined by the sum of a steady term (QCYLXVCYL) and a transient term (DCM).

However, since this value QAINJC is in volume units, it may change due to changes in intake air temperature, so it is converted into mass units using KTA as a correction coefficient (steps 61 to 63).

Also, QCYL is QlllQ with 2 as a smoothing constant.
Weighting using CYL-1 as a variable and K2 as a weight is determined using an average value (steps 54 to 57).

Next, the variable Quo fKFLAT'i% is determined from the flow path area of the intake system and the engine speed. This is because the air amount sensor is eliminated from the intake system to reduce costs and facilitate maintenance.

Therefore, the flow path area is determined by the following equations (6G) and (611) (steps 41 to 52).

AADNV=AAXTrer/VCYL-(6G
) AA=ATVO+A I+AAC...(all> However, AADNV: Channel area/(Rotation speed x Schilling volume>(cm2/rpm-cc) AA: Total channel area (CI
I12) ATVO: Throttle valve flow path area (c+++2>AI: 5V2
6, the flow path surface fff (cm”) AAC: 5V27 flow path area (cI112).

In other words, this system uses the throttle valve opening T as a load signal.
Although the flow path area ATVO based on VO is adopted, if there is a passage 23 that bypasses the crest valve 21,
These areas AI and AAC must also be taken into account. Therefore, the total flow area AA is determined by the flow area ATVO based on the throttle valve opening and the flow area of the bypass passage (AI or AA).
C) (steps 41 to 49).

Note that these 5V2G and 27 are two-position valves. This is to reduce costs by performing four-stage control instead of using a duty control solenoid valve.

Further, in actual control, a value AA/N (corresponding to the part AAXTref in step 52) obtained by dividing the total flow path area AA by the rotation speed N is adopted.

If AA is used as it is, it will have a region that changes suddenly as N changes, so if this is used as a parameter,
Accuracy decreases in this sudden change region. however,
For example, increasing the number of grid points in a map in order to improve accuracy will also significantly increase the calculation time. Therefore, A
By employing A/N, these control problems have been solved.

Therefore, this AADNV(=AAXTre4/VC
Linearized air flQHo is determined using (step 53). In addition, the flat air-fuel ratio coefficient KFL
AT is obtained from the map using QIIOIN as a parameter, and the throttle valve flow area ATVO is obtained from a table using TVO as a parameter (step 54.42).

Mainly, the basic intake temperature correction coefficient KTAO and the intake temperature load correction coefficient KTAQCYL are also searched using the intake temperature TAIQCYL as a parameter, and the intake temperature correction coefficient KTA is calculated by the product of these. (Steps 81 to 83 in FIG. 7).

Since the air fiQA+NJ of the injection valve section has been determined by the above calculation, the next step is to determine the correction amount for the fuel delay that occurs during the transient period. This correction unit is the KAT HOS used in step 66, and is specifically calculated in the routine shown in FIG.

In this example, it is determined based on the deviation between the equilibrium adhesion amount M F H and the calculated value of the adhesion amount that changes with a first-order lag with respect to the change in the equilibrium adhesion amount. Expressing this numerically, the following group of equations (7^
) to (7E).

K A T HOS = V M F X
G f(F...(78)VMF=
(MFH-MF-,)XKMF...(7B) MF=MF-, 10VMF...(7C)K
MF = (KMF AT + KMF
V MF )XKMFNXKMFDBT...(7D) GHF=GHFQCYL XGHFFBYA...(7
E) However, KATHO8: transient correction fi (μs) VMF:
Deposition rate (μS/spray) MFH: Equilibrium deposition amount (μS) MF: Deposition amount (μS) KMF: Volume ratio (%) KMFAT: Basic volume ratio (%) KMFVMF: Deposition speed correction factor for volume ratio (%) KMFN : Rotation correction rate of quantity ratio (%) KMFDBT:
Boost correction factor (%) of quantity ratio G HF : Correction factor (%) GHFQCYL : Deceleration correction yg (%) G HF F B Y A : Air-fuel ratio correction factor (%).

In other words, the deviation (MFI) between the equilibrium adhesion amount M
-f-MF-+) is multiplied by a coefficient KMF representing the rate at which the calculated value of the adhesion amount approaches per unit period (per injection), the adhesion speed VMF is determined (step 1o3) .

Here, the equilibrium adhesion amount M F H is the basic operating variable QA
Since it depends on not only I N J IN but also the cooling water temperature TW, there are a total of three parameters, and since there is one too many parameters, it is impossible to create a three-dimensional map as it is. Therefore, in this example, this problem is solved by a combination of three-dimensional map search and linear approximation interpolation calculation. In other words, different n (=4 or 5) set in advance within the range of temperature change that the cooling water temperature Tw can actually take.
Standard temperature Tuba −Tlun (Two > ・=
n pieces of adhesion amount data are prepared by actual measurement to give the adhesion amount MFHTwn at the reference temperature Twn using QA I N J and N as parameters. Then, the reference temperature T u+k(k
is an integer from O to n), using the attachment fiMFHTwk and MFHTwk+1 at Tl1Ik+1, TIL
The MFH is finally determined by interpolation calculation using T u+k + I on l+ T u+ (step 101).
).

In addition, high accuracy can be obtained with the method using a map and a compensator, but if you want to increase the calculation speed even if the accuracy is moderate, there is also a method that uses two tables.
This is shown in the following equation (7F).

MFHTu+n=MFHQnXMFHNn ・-(7F
) However, MFHQn: Coefficient M based on QAI N J
PHNn: is a coefficient based on N, and M F HQ n is a coefficient based on QA I N J
F I (N n is determined by table search using N as a parameter.

Note that when Tl1l>Tlll0 and Ta1I<
Since interpolation cannot be performed during Turn,
Let MFH=MFHTiuo. Furthermore, during fuel cut, MFH=FCMFH (constant value).

On the other hand, the adhesion calculated last time! The current adhesion amount MF is calculated by adding the adhesion speed VMF obtained this time to (MF-+).
is calculated (step 104).

Next, the quantity ratio KMF may be a constant value, but in this example, the basic value KMFAT is obtained by map search using AADNV and Tu+ as parameters, and further correction based on the bypass value DBO8T of MF, N, and boost pressure change amount is implemented. 〒
There is. That is, the correction coefficients for the basic value KMFAT are three coefficients KMFV MF, KMFN
, KMFDBT, and these are introduced so that the air-fuel ratio at the initial stage of the transient has a characteristic of 7-rat. In other words, there is a slight lack of correction during slow acceleration, and errors occur due to differences in rotational speed.When conducting experiments, slight deviations occur, and these should be resolved individually.

In addition, the bypass value DBO8T is calculated from the following formula (7G) to (7T)
The content is a value that gradually dissipates in synchronization with the Ref signal while incorporating a minute change in boost pressure.

(1) When setting (first time) DBO3T=DBO3T-.

+ (BOO8T-BOO3TO) ... (7G) (2) Attenuation (D B OS T2O) (from the second time)
DBO8T=DBO5T-I XTGEN...(7
+1) (3) Attenuation (DBOST < O) (second time onwards) DBOST=DBO3T-+ XTGENG...
・(7■) However, BOO6T nibost pressure BOO9TO: Previous boost pressure TGEN: Damping coefficient during acceleration (constant) TGENG: Damping coefficient during deceleration (constant) Boost pressure BOO8T is AADNV, and the quantity ratio The adhesion speed correction factor KMFVMF is ■M F -H, the rotation correction factor KMFN of the quantity ratio is N, and the boost correction factor K of the quantity proportion
MFDBT is obtained by table search using the absolute value of DBO3T as a parameter.

Next, the correction factor GHFQCYL is a value that takes into consideration differences in fuel properties, etc. (step 131). This is because highly volatile fuels rapidly vaporize due to the development of negative suction pressure during deceleration. Since it is inhaled into the flash cylinder, the amount of fuel that reaches the cylinder is correspondingly smaller than that of less volatile fuel.

For this reason, during deceleration, it is necessary to estimate the amount of adhesion to be that much smaller, and conversely, it is sufficient to assign a smaller value to the correction coefficient (GHFQCYL). In other words, no correction is made during acceleration (when V MF is positive), but (GH
FQCYL=1.0), and a value of 1 or less is used during deceleration (when V MF is negative).

In addition, the correction factor G HF F B Y A is the target air-fuel ratio T
FB YA 75 (This is a value introduced in response to the tendency of over-correction when the air-fuel ratio becomes leaner than the basic air-fuel ratio, and is calculated and calculated according to the target air-fuel ratio TFBYA (steps 132 to 134). ).As mentioned above, this is a characteristic part of the present invention.

In addition, deceleration correction IGHFQ CY L l! QCY
L is the air-fuel ratio correction factor G HF F B Y A is TFB
It is determined by table search using YA as a parameter.

Using the thus obtained VMF and GHF, the transient correction amount /~THOS is finally determined (step 7).
B1+)8).

Next, the air-fuel ratio correction coefficient LAMBDA and the target two-fuel ratio TFBYA used in steps 68 and 64 in FIG. 3(C) are calculated in the conventional example, and their routines are shown in FIGS. 5 and 6, respectively. It is.

That is, LAMBDA is a correction coefficient in air-fuel ratio feedback control. Figure 5 is an example of PID control, where the actual air-fuel ratio (specifically, the oxygen sensor output Ip) and the target value of the air-fuel ratio (specifically, the sensor output equivalent amount T +
The following equation (8^) ~ (
8D), LAMBDA is determined (step 111).
~118).

LAMBDA=P+I+D...(8^
) P=KP-ER...(8B) I=I-1+, -ER...(8C) D=KD ・(
ER-ER-+) ... (8D) However, KP:
Proportional gain: Integral gain KD: Differential gain.

Note that the deviation ER is given by the following equation (8E) (step 114).

ER"Ip-T+ p-(n+ + ) = 18
E) Here, the second term of opening formula (8E) indicates the sensor output I + when the Ref signal was input (n+ 1 ) times ago (where n is the number of electric tubes). This is done in consideration of the fact that there is a time delay until the result of the air-fuel ratio set in the intake system is detected by the sensor 34 provided in the exhaust system.

In addition, the target air-fuel ratio TFBYA is Tw, Q CY L I
Calculated using N as a parameter (step 9 in Figure 6)
1-95). Incidentally, step 95 in the same figure sets an upper limit value and a lower limit value for TFBYA, and gives it the function of 7-else-7.

Next, step 65 in FIG. 3(C). f37-t' The learning correction coefficients KBLRC and KBTLRC are used. In this example, since the air amount (QAINJ) and the fuel delay correction amount (KATHO8) are calculated separately, the learning correction coefficients are We have also decided to separate them and conduct them independently. In other words, the basic injection amount learning correction coefficient KBLRC is determined by the fuel delay learning correction coefficient KBTLRC in the calculation routine of the air-fuel ratio correction coefficient LAMBDA.
is calculated in the calculation routine of the transient correction amount KATHO3 (steps 119 and 120 in FIG. 5, steps 107 to 110 in FIG. 4).

Learning correction basically adds a control amount based on the deviation from the target value in advance to prevent deviation from occurring during the next calculation.KBL RCl! LA
To MBD A, KBTLRC is this LAMBDA
It is further calculated based on the deviation B between the actual air-fuel ratio AFBYA and the target air-fuel ratio TFBYA (steps 119 and 12).
0.107-110).

In addition, depending on the comparison between the adhesion speed VMF and the reference value L1, what is the steady state (VMF<L+) is the transient state (VMF≧L+)
Then, learning is performed for KBLRC only during steady state and for KBTLRC only during transient state (steps 119, 107).

Next, FIG. 9 is a flowchart of a second embodiment of the present invention.

In this example, the target of correction is the equilibrium adhesion amount, and when it is determined that the target air-fuel ratio is leaner than the basic air-fuel ratio, the air-fuel ratio is adjusted to the equilibrium adhesion amount M F l-I S with respect to the basic air-fuel ratio. A correction coefficient CFBA (a constant smaller than 1 or a function value of the target air-fuel ratio) is multiplied (step 13
2,135). Further, this correction coefficient KFBA is also introduced for the quantity ratio KMF, and the quantity proportion (basic quantity ratio KMFS) with respect to the basic air-fuel ratio is corrected (steps 132 and 136).

This is different from the first embodiment in which the deposition rate VMF is the subject of correction, whereas the two parameters (equilibrium deposition amount and quantity ratio) that provide VMF are each corrected. There is no change in the fact that the same effects are produced.

(Effects of the Invention) As explained above, the present invention provides a means for calculating the basic fuel injection amount according to the operating condition, an equilibrium adhesion of intake system fuel with respect to the basic air-fuel ratio -1, and this equilibrium adhesion amount. An internal combustion engine (commercial combustion engine) comprising: a means for calculating a correction amount at a transient time based on a calculated value of the adhesion amount that changes with a first-order lag; and a means for correcting the basic injection amount using the transient correction amount. In the air-fuel ratio control device, means for determining whether or not a target air-fuel ratio determined depending on the operating state is leaner than the basic air-fuel ratio; Since a means for reducing the transient correction amount set for the basic air-fuel ratio is provided, the leaner the target air-fuel ratio becomes, the smaller the calculated transient correction amount is, thereby ensuring that the required amount is not over-corrected. It matches well with the transient correction amount, and can prevent poor exhaust emissions at the initial stage of the transient.

[Brief explanation of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention, FIG. 2 is a schematic diagram showing the mechanical configuration of the first embodiment of the present invention applied to a 5PIvc arrangement, and FIGS. 3 to 7 are the same as those in FIG. FIG. 8 is a flowchart illustrating the contents of the operations executed in the control unit, FIG. 8 is a characteristic diagram of the amount of transient correction illustrating the operation of this embodiment, and FIG. 9 is a flowchart of the second embodiment of the present invention. FIG. 10 is a characteristic diagram showing changes in the transient correction amount with respect to the air-fuel ratio. DESCRIPTION OF SYMBOLS 1... Basic injection amount calculation means, 2... Transient correction amount calculation means, 3... Basic equilibrium adhesion amount calculation means, 4... Adhesion speed calculation means, 5... Adhesion amount calculation means, 6 ...Injection amount correction calculation means, 7.Target air-fuel ratio determination means, 8.
- Correction calculation means, 21... Intake throttle valve, 22... Intake passage, 23... Bypass passage, 24... Fuel injection valve, 25... Throttle valve opening sensor, 34... Oxygen sensor (air-fuel ratio sensor), 35...control unit. (1 other person) Figure 6 Figure 8 Time Figure 10 Temporary Opening

Claims (1)

[Claims] A means for calculating the basic fuel injection amount according to the operating condition, an equilibrium adhesion amount of intake system fuel with respect to the basic air-fuel ratio, and a calculated value of the adhesion amount that changes with a first-order lag with respect to this equilibrium adhesion amount. In an air-fuel ratio control device for an internal combustion engine, the air-fuel ratio control device for an internal combustion engine includes means for calculating a transient correction amount based on the transient correction amount, and means for correcting and calculating the basic injection amount based on the transient correction amount. means for determining whether or not the air-fuel ratio is leaner than the basic air-fuel ratio, and when it is determined that the air-fuel ratio is lean based on the determination result, reducing the transient correction amount set for the basic air-fuel ratio; 1. An air-fuel ratio control device for an internal combustion engine, comprising: means.