JPH0227133A - Air-fuel ratio control device for internal combustion engines - Google Patents

Abstract

PURPOSE:To improve the converging property of feedback control by operating the differential value of the change of air-fuel ratio for each defined minute time and setting a feedback correction factor for each defined minute time using the differential value. CONSTITUTION:A deviation operating means D operates the deviation of an air-fuel ratio detected by an air-fuel ratio detecting means C from a target air-fuel ratio and a time synchronous differential value operating means E operates the differential value of the detected air-fuel ratio for each defined minute time. Since the tendency of air-fuel ratio can be estimated from these deviation and differential value, a time synchronous feedback correction factor setting means F sets a feedback correction factor for each defined minute time based on the deviation and differential value. A fuel injection quantity operating means G operates a fuel injection quantity based on a fundamental fuel injection quantity and a feedback correction factor which are set by a fundamental fuel injection quantity setting means B and the setting means F. A fuel injecting means H is operated by a driving signal corresponding to this fuel injection quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an air-fuel ratio control device for an internal combustion engine having an electronically controlled fuel injection device. The present invention relates to an air-fuel ratio control device configured to feedback control the fuel injection amount based on the detection result.

<Prior Art> An electronically controlled fuel injection system for an internal combustion engine is equipped with an electromagnetic fuel injection valve in the engine intake system, and is configured to control engine operating state parameters related to the amount of air taken into the engine (e.g. engine intake air flow rate and engine Set the basic fuel injection amount based on the
This is multiplied by a feedback correction coefficient for air-fuel ratio feedback control to obtain the final fuel injection amount, and a drive pulse signal with a pulse width corresponding to this fuel injection amount is sent at a predetermined timing synchronized with the engine rotation. By outputting to the fuel injection valve, the fuel injection amount is controlled and the optimal amount of fuel is injected and supplied to the engine.

Regarding air-fuel ratio feedback control, an oxygen sensor is provided in the engine exhaust system, and the air-fuel ratio of the engine intake air-fuel mixture, which is closely related to the oxygen concentration in the engine exhaust detected by the oxygen sensor, is detected. The detected air-fuel ratio is compared with the stoichiometric air-fuel ratio, which is the target air-fuel ratio, to determine whether it is rich or lean, and based on this, the feedback correction coefficient is changed to feedback-control the air-fuel ratio to the stoichiometric air-fuel ratio. .

Specifically, as shown in Figure 7, the output voltage of the oxygen sensor is compared with the slice level voltage corresponding to the stoichiometric air-fuel ratio, which is the target air-fuel ratio, and when the output voltage is large, it is rich, and when the output voltage is small, it is rich. is determined to be lean, and based on this determination result, a feedback correction coefficient is set and controlled by proportional/integral (pH control).For example, when rich (lean), the feedback correction coefficient is set first, then the proportional constant is The air-fuel ratio is controlled to approach the stoichiometric air-fuel ratio by decreasing (increasing) the integral constant by 1 minute in time synchronization or rotation synchronization (see Japanese Patent Laid-Open No. 60-240840, etc.).

<Problems to be Solved by the Invention> However, the responsiveness of oxygen sensors is generally poor, so when the output voltage of the oxygen sensor crosses the slice level voltage, the actual air-fuel ratio tends to be richer or leaner than the target air-fuel ratio. A lot has changed. For this reason, the amount of overshoot and undershoot becomes large (and as a result, the air-fuel ratio fluctuates greatly, making it difficult to converge to the target air-fuel ratio, causing deterioration in drivability due to surge torque and CO in the exhaust gas. , HC, NOx, etc. may increase.

In order to solve such problems, the applicant first calculated the deviation of the detected air-fuel ratio (oxygen sensor output voltage) from the target air-fuel ratio (slice level voltage) and the detected air-fuel ratio (oxygen sensor output voltage). ) proposed an air-fuel ratio control device configured to predict the trend of the air-fuel ratio and set a feedback correction coefficient based on the differential value of
(See issue 07).

By the way, when setting the feedback correction coefficient by rich/lean judgment for the target air-fuel ratio, it is sufficient to judge the rich/lean at that point, so even if the feedback correction coefficient setting is performed in synchronization with the engine rotation, There is no difference in air-fuel ratio control even if it is executed in time synchronization. However, in the case of the configuration in which the feedback correction coefficient is set based on the air-fuel ratio deviation and the differential value as described above, if the differential value is determined by rotation synchronization, the gate time becomes long as shown in Fig. 8. (The detection accuracy of the differential value decreases on the low rotation side, and the differential value differs depending on the rotational speed at that time for the same air-fuel ratio fluctuation, so there was a problem that accurate feedback control could not be performed.

The present invention has been made in view of the above problems, and is configured to set a feedback correction coefficient based on the deviation of the air-fuel ratio from the target air-fuel ratio and the differential value of the air-fuel ratio change. The purpose is to improve the convergence of feedback control by accurately determining

<Means for solving the problem> Therefore, in the present invention, as shown in FIG.
An air-fuel ratio control device for an internal combustion engine includes the means.

(A) Engine operating state detection means for detecting the engine operating state (B) Basic fuel injection amount setting means for setting the basic fuel injection amount based on the engine operating state detected by the engine operating state detection means (C) Engine exhaust Air-fuel ratio detection means (D) that detects the air-fuel ratio of the air-fuel mixture taken into the engine by detecting the components; Deviation calculation means (E) that calculates the deviation of the detected air-fuel ratio from the target air-fuel ratio; Time-synchronized differential value calculating means (F) for calculating the differential value of the air-fuel ratio at predetermined minute intervals; a feedback correction coefficient for feedback correcting the basic fuel injection amount based on the deviation and the differential value; time-synchronized feedback correction coefficient setting means (G) that calculates the fuel injection amount based on the basic fuel injection amount set by the basic fuel injection amount setting means and the feedback correction coefficient set by the feedback correction coefficient setting means; The fuel injection amount calculation means (I
I) Fuel injection means that injects fuel into the engine on and off based on the drive pulse signal corresponding to the calculated fuel injection amount (Operation) Based on the engine operating state detected by the engine operating state detection means A, the basic The fuel injection amount setting means B sets a basic fuel injection amount that substantially corresponds to the target air-fuel ratio.

On the other hand, the air-fuel ratio is detected by the air-fuel ratio detection means C, the deviation calculation means calculates the deviation of the air-fuel ratio from the target air-fuel ratio, and the time-synchronized differential value calculation means E sets the differential value of the detected air-fuel ratio to a predetermined value. Calculate every minute time.

Since the trend of the air-fuel ratio can be predicted based on these deviations and the differential value, the time-synchronized feedback correction coefficient setting means F sets the feedback correction coefficient at every predetermined minute time based on these deviations and the differential value.

The fuel injection amount calculation means G corresponds to each setting means B described above.

The fuel injection amount is calculated based on the basic fuel injection amount and the feedback correction coefficient set by F. and,
The fuel injection means H is actuated by a drive pulse signal corresponding to this fuel injection amount.

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

In FIG. 2, an 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 branch portion of the intake manifold 5 is provided with a fuel injection valve 6 as a fuel injection means for each cylinder. The fuel injection valve 6 is an electromagnetic fuel injection valve that opens when the solenoid is energized and closes when the energization is stopped. Fuel is injected and supplied by a pump and adjusted to a predetermined pressure by a pressure regulator.

Although this example is a multi-point injection system, it may also be a single-point injection system in which a single fuel injection valve is provided in common to all cylinders, such as upstream of the throttle valve 4.

An ignition plug 7 is provided in the combustion chamber of the engine 1, which ignites a spark to ignite and burn the air-fuel mixture.

From the engine 1, an exhaust manifold 8 exhaust duct 9. Exhaust gas is discharged via a three-way catalyst 10 and a muffler 11. The three-way catalyst 10 is an exhaust purification device that oxidizes Co HC in the exhaust components and reduces NOx to convert it into other harmless substances, and its conversion efficiency is closely related to the air-fuel ratio of the intake air-fuel mixture. In a relationship.

The control unit 12 includes a CPU and a ROM.

It is equipped with a microcomputer including a 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. .

As the various sensors described above, a hot wire type air flow meter 13 is provided in the intake duct 3, and outputs a voltage signal according to the intake air flow rate Q.

Further, a crank angle sensor 14 is provided, and in the case of a four-cylinder engine, outputs a reference signal for every 180 degrees of crank angle and a unit signal 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 or the number of unit signals generated within a predetermined time.

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

These air flow meters 13. The crank angle sensor 14 and the like correspond to the engine operating state detection means.

Further, an oxygen sensor 16 as an air-fuel ratio detecting 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 made of, for example, a zirconia (ZrOz) tube, which is an oxygen ion conductor used as a solid electrolyte for concentration batteries, and has a cylindrical shape with a bottom and a closed end facing the exhaust gas. It generates an electromotive force depending on the ratio of oxygen concentrations.

Then, a platinum catalyst layer is provided on the outer surface of the zirconia tube by vapor-depositing platinum that functions as an oxidation catalyst. By combining unburned components such as and CO, the oxygen concentration on the outside is reduced to almost zero, increasing the ratio of oxygen concentration inside and outside and generating a large electromotive force, while in a lean mixture, the difference in oxygen concentration is small. This is a well-known method in which almost no voltage is generated and the electromotive force suddenly changes around the stoichiometric air-fuel ratio, as shown in FIG.

Furthermore, the throttle valve 4 has an opening degree TV of the throttle valve 4.
A throttle sensor 17 for detecting O with a potentiometer is also attached.

Here, the CPU of the microcomputer included in the control unit 12 performs arithmetic processing according to the program on the ROM shown as the flowcharts of FIGS. 4 to 6, and controls fuel injection. In this embodiment, the functions of the control unit 12 as a basic fuel injection amount setting means, a fuel injection amount calculation means, a 1-hour opening period feedback correction coefficient setting means, and a deviation calculation means as a 5-hour opening period differential value calculation means are as shown in the flowchart. It is provided in software as shown.

The routine shown in the flowchart of FIG. 4 is an air-fuel ratio feedback control routine, which is executed at predetermined minute intervals (for example, 10 m5) to control the deviation of the air-fuel ratio from the target air-fuel ratio and the differential value of the air-fuel ratio in time synchronization. The feedback correction coefficient α is set based on these values.

First, in step 1, the output voltage from the oxygen sensor 16 is
. 2, and in the next step 2, the output voltage ■. 2
The differential value ΔE of is calculated based on the following formula.

Here, Voz-30+ VO2-20+ VO2-1
0 is 30m5 in front, 20m5 in front, 10n+ respectively.
The output voltage of the oxygen sensor 6 before s. It is 2.

In this way, the output voltage V was determined at three different gate times: 30+ns, 20m5, and 10m5. If the amount of change (differential value ΔE) of 2 is averaged to finally obtain the differential value ΔE, the output voltage V. Even if 2 is disturbed due to the influence of noise or fuel distribution, the disturbance can be prevented from greatly affecting the differential value ΔE.

Furthermore, as mentioned above, in this embodiment, the differential value ΔE is obtained in time synchronization, so the same differential value ΔE will be set for the same air-fuel ratio fluctuation even if the engine speed N is different. Therefore, variations in the differential value E due to the influence of the engine rotational speed N do not occur. Therefore, E can be accurately determined as a differential value indicating the rate of change of the air-fuel ratio,
This improves the accuracy of the air-fuel ratio feedback control using the feedback correction coefficient α, which is also set in time synchronization, as will be described later, and improves the degree of convergence to the target air-fuel ratio.

In step 3, it is determined whether the differential value ΔE calculated in step 2 is a positive value or a negative value, and if it is positive, the output voltage of the oxygen sensor 16 is set to ■. If it is determined that 2 indicates an increasing tendency, the process proceeds to step 4, where it is determined whether the flag is positive or negative. The first time the differential value ΔE is determined to be positive, the flag is negative as will be described later, so the process goes to step 5 and calculates the minimum value ■ according to the weighted average calculation of the formula below. 2 Set the old N.

Also, in the next step 6, the flag is set to positive, and even if the differential value ΔE is positive next time, the step 5 is jagged to the minimum value ■. 2 Prevent old N operations from being performed. That is, the output voltage ■. 2 reversed from a downward trend to an upward trend,
When the differential value ΔE is determined to be positive for the first time, the output voltage V is reached. 2. Determine that it is the peak of the valley of change and set the minimum value■
. This is to calculate Z and M I N.

In this way, when the weighted average calculation in step 5 is performed and the flag is set positive, when E is inverted to a negative differential value, that is, the minimum value ■. When 2 is at its peak, from an upward trend to a downward trend, the process proceeds from step 3 to step 7, and if the flag is determined to be positive, the process proceeds to step 8. In step 8, the weighted average of the following formula is calculated. ■ Maximum value according to the calculation. 2MAX is set, and in the next step 9 the flag is set to negative.

If the differential value E continues to be negative, it is determined in step 7 that the flag is negative, and step 8
Maximum value at■. 2MAX operation is not performed.

Further, when the differential value ΔE is reversed from negative to positive in this way, step 3 goes to step 4, and further,
By proceeding from step 4 to step 5, the output voltage V.

The peak of the valley of 2 is detected and the minimum value V. An operation to obtain 2 is performed.

In this way, the output voltage V is determined by weighted average calculation. The maximum value of 2 is V. , MAX and minimum value■. If we calculate 2MIN, the output voltage ■. Even if a disturbance unrelated to the air-fuel ratio occurs in 2, the maximum value of this disturbance is ■. 2MAX and minimum value■
. It can be avoided that the calculation of 2MIN is affected.

Furthermore, the output voltage of the oxygen sensor 16 is ■. 2. Since the changes in the characteristics are gradual, the maximum value ■ is obtained by calculating the weighted average every minute time as described above. m'M A X and minimum value■. 2MI
The maximum value VozM is determined only at the initial stage of restart without determining N.
AX and minimum value ■. 2MIN is determined, and while the engine is running, the average value SL is set based on the value determined at the initial stage of startup, and the maximum value SL is set each time the engine is stopped. 2MAX and minimum value V.

2 old N may be cleared, and the maximum value ■ at the initial stage of startup mentioned above. 2MAX and minimum value■. 2M
A weighted average calculation may also be performed when determining IN.

Then, in step 10, the output voltage of the oxygen sensor 16 is determined as described above. Maximum value of 2■. 2MAX and minimum value■. Find the simple average value SL with 2MIN.

Therefore, the average (l!!SL) obtained here is the output voltage V of the oxygen sensor 16.2 If the characteristics change and, for example, the maximum value V.2 MAX decreases compared to the initial state, the It changes.

In the next step 11, the maximum value ■ obtained in each initial state of the engine is determined. 2MAX, average value SL, and current maximum value ■. 2MAX and the average value SL, a correction coefficient Rration on the air-fuel ratio rich side of the differential value ΔE of the output of the oxygen sensor 16 is calculated based on the following formula.

In addition, in the next step 12, the minimum value ■ obtained in the initial state. 2 MIN and average value SL, and the current minimum value■. 2111N and the average value SL, the oxygen sensor 16 output voltage ■. Correction coefficient L r a ti on the air-fuel ratio lean side of the differential value ΔE of 2. 7 is calculated based on the following formula.

In this way, the output voltage of the oxygen sensor 16 ■. If the differential value ΔE is corrected based on the change from the initial state of the engine in the two characteristics, for example, the output voltage will change from the initial state to ■. Even if the slope (change speed) with respect to the air-fuel ratio change in No. 2 becomes slow, the degree of convergence to the target air-fuel ratio can be determined with high accuracy from the differential value ΔE.

Then, in step 13, the average value SL calculated in step 10 and the output voltage (■) of the oxygen sensor 16 read in step 1 are calculated. 2 to determine whether the current air-fuel ratio of the intake air-fuel mixture is richer or leaner than the target air-fuel ratio defined by the average value SL.

In step 13, if it is determined that VO2>SL and the air-fuel ratio is rich with respect to the target air-fuel ratio, the process proceeds to step 14, where the current output voltage ■ is determined. The deviation E (←V, 2-3L) between 2 and the average value SL is calculated. In the next step 15, as shown in the formula below, the ratio of the actual deviation E to the current maximum rich-side deviation is determined, and this ratio is set as the R-fuzzy quantity U representing the rich-side deviation with respect to the target air-fuel ratio. .

That is, the R-fuzzy amount U is 1 when the deviation E is maximum, and approaches zero as the rich side deviation amount becomes smaller.

Here, the average value SL used for rich/lean judgment of the air-fuel ratio and calculating the deviation E and the R-fuzzy amount U.
is the current maximum value ■ in the step IO mentioned above. 2MAX and minimum value■. Since the calculation is based on 21'lIN, the oxygen sensor 16 has deteriorated and its output voltage ■. 2
Even if the characteristics deteriorate overall or the rate of change near the stoichiometric air-fuel ratio changes, the rich/lean judgment can be performed correctly and the R-fuzzy quantity U can approximately correctly indicate the air-fuel ratio enrichment tendency. Become.

That is, the maximum value V,2 in the initial state of the oxygen sensor 16
MAX and minimum value■. , MIN as the slice level voltage, and if the slice level voltage is used to determine the deviation E even after the oxygen sensor 16 has deteriorated, the output voltage (2), for example. 2 decreases in the overall direction, it will be judged as lean in the original rich state, and at the time of rich judgment, it will be erroneously judged as if the air-fuel ratio thread on the rich side has decreased, and the air-fuel ratio will be lower than the target air-fuel ratio (stoichiometric air-fuel ratio). It ends up being controlled by the Morin side.

However, in this embodiment, the output voltage of the oxygen sensor 16 is . 2 Changes in characteristics, ie, output voltage V. Maximum value of 2■.

2MAX and minimum value■. 2MIN and the average value SL is determined as the rich/lean judgment level and the R fuzzy quantity U.
Since it is used as a calculation standard, it is possible to approximately accurately capture the rich tendency, and as a result, even if the output voltage of the oxygen sensor 16 is Even if there is a change in the two characteristics, feedback control can be performed with good convergence around the target air-fuel ratio.

In the next step 16, the differential value calculated in step 2 is added to the correction coefficient Rr a calculated in step 11.
Ti. Correct by multiplying by 7 to set the final differential value ΔE.

Here, the maximum value ■ than the initial state. When 2MAX -3L becomes small, the output voltage ■. 2 is in a state where it is smaller during the change, so the differential value ΔE is corrected to be larger than in the initial state to cope with the decrease in the range of change, and conversely, the maximum value ■ is smaller than in the initial state. 2MAX-3L
is large, that is, when the output voltage (2) o2 changes greatly, the differential value ΔE is corrected to decrease so as to make it appear as if it were changing slowly, in order to cope with the increase in the range of change.

When it is determined that it is rich in step 13, the above processing is performed, but in step 13, V is determined. Similar processing is performed when it is determined that 2<SL and the air-fuel ratio is lean.

That is, if it is determined that the air-fuel ratio is lean, step 1
Proceed to step 7 and calculate the output voltage ■ from the average value SL. 2 to find the deviation E, while in step 18 step 15
In the same way as above, a fuzzy quantity U representing the lean side deviation with respect to the target air-fuel ratio is calculated.

In the next step 19, the correction coefficient 1-'riltio, calculated in step 12 is used to correct the differential value ΔE in the same manner as in step 16, and the final value E is determined, and the oxygen sensor This corresponds to the change in the range of change due to deterioration of 16.

Meanwhile, ■ in step 13. , '=SL and it is determined that the current air-fuel ratio is approximately the target air-fuel ratio, the process proceeds to step 20 and sets the differential value ΔE calculated in step 2 as the final value ΔE'', and In the next step 21, the deviation E is set to zero.

Average value SL and output voltage■. After the fuzzy quantity U and the differential value ΔE' are set as described above based on the air-fuel ratio determination by comparison with 2, the process proceeds to the next step 22 and the feedback correction coefficient α is set.

In step 22, first, the differential value ΔE'' is set to a positive maximum value PB, a positive intermediate value PM, and a positive minimum value PS.

While converting into seven levels of values: zero Z, negative minimum value NS, negative intermediate value NM, and negative maximum value NB, the fuzzy quantity U obtained in step 15 or step 19 is converted into a value in the range of 1 to 0 to 1. Based on these step values (degree of convergence and deviation of air-fuel ratio), set the step value of the feed pack correction coefficient α from a preset map, and use this step value to calculate the current feedback correction. Set the coefficient α.

Here, for example, when the step value is zero, the feedback correction coefficient α is set to 1, and the feedback correction coefficient α is set by increasing or subtracting from 1 according to the positive/negative and magnitude of the step value.

In the next step 23, a new learning correction coefficient KBLRC is set by weighting the feedback correction coefficient α obtained in step 22 this time and the previous learning correction coefficient KBLRC according to the following formula.

Further, in step 24, the output voltage ■ inputted this time is used for calculating the differential value ΔE next time. 2 to 10m
Data from 5 days ago■. 2-10, this time 10m
Data from 5 days ago■. 20m5 treated as 2-10
Previous data■. 2-20, and furthermore, this time 2
Data from 0m5 ago■. 30 which is treated as 2-2°
Data V before m5. Set as 2-30.

The weight constant X in the weighted average formula in step 23 is set according to the routine shown in the flowchart of FIG.

This routine is executed every predetermined minute time (for example, 10 m5), and first, in step 31, the opening degree TVO of the throttle valve 4 detected by the throttle sensor 17 is input, and in the next step 32, the previous input is input. By comparing with the value, the opening change rate Δ per execution cycle of this routine is determined.
Calculate TVO.

Then, in step 33, it is determined whether or not the opening change rate ΔTVO calculated in step 32 exceeds a predetermined value (for example, 1°). Proceed to step 34.

In step 34, the weighting is a correction coefficient X rat of a constant
i.

Set the countdown timer value Tm to a predetermined time (for example, 500 m5), and proceed to the next step
Then, the correction coefficient X r B t□. Let be zero.

On the other hand, if it is determined in step 33 that the opening change rate ΔTVO is less than a predetermined value (for example, 1°) and the engine is in a steady operating state, the process proceeds to step 36, where the timer value T
A new timer value Tm is set by subtracting m by the execution cycle (10 ms) of this routine. Next step 37
Then, in step 36, it is determined whether or not the timer value Tm resulting from the subtraction is less than or equal to zero. If it is less than zero, the process proceeds to step 38 and the timer value Tm is set to zero, but it is determined that the timer value Tm exceeds zero. Sometimes, the process skips step 38 and proceeds to step 39.

In step 39, the correction coefficient X r a ti is determined from the map based on the timer value Tm. Find it by searching. Here, when the timer value Tm is the predetermined value set in step 34, the correction coefficient X raLiQ is set to zero, and increases as the timer value Tm decreases from the predetermined value and approaches 1 (100%). , the correction coefficient X r m t i becomes zero. is set to 1. Therefore, during transient operation of the engine, the correction coefficient
rati. The correction coefficient
Ti. is set to 1.

In the next step 40, the weights set for each of a plurality of operating states divided by the basic fuel injection amount Tp and the engine rotational speed N, which are set as described later, are calculated using the basic value X BASE of the constant X. In step 41, the correction coefficient X is added to this basic value X BASE.
ra ti. Multiply the weight by setting a constant X.

In the weighting set in this way, the constant X is used in the weighted average calculation in step 23 described above, and during transient operation, the weighting constant
Learning correction coefficient K B LRC - feedback correction coefficient α.

The routine shown in the flowchart of FIG. 6 is a fuel injection amount setting routine that is executed every predetermined minute period (for example, 10 m5). First, in step 51, the intake air flow rate Q detected by the air flow meter 13 is inputted, In the next step 52, a basic fuel injection amount 'rp (←KXQ/N, is a constant) is calculated based on the engine rotational speed N detected by the crank angle sensor 14 and the intake air flow rate Q.

In addition to calculating the basic fuel injection amount Tp based on the intake air flow rate Q detected by the air flow meter 13 as described above, the intake pressure PB is calculated instead of the air flow meter 13.
A basic fuel injection amount T is provided based on the intake pressure PB detected by the intake pressure sensor.
Alternatively, p may be calculated.

That is, in step 53, the intake pressure PB detected by the intake pressure sensor is input. In the next step 54, first, the basic volumetric efficiency KPH is searched and set from the map based on the intake pressure PB, and the intake pressure PB is
The current P is calculated from a map that stores the minute correction coefficient K FLA for each operating state divided by
A corresponding minute correction coefficient KFLAT is searched and set based on B and N, and the basic volumetric efficiency KPM is multiplied by the minute correction coefficient KFLAT to obtain the volumetric efficiency QcYL of fresh air.

Then, in the next step 55, the basic fuel injection amount Tp is calculated according to the following formula.

T p'-KcoNX QCYL X KTAX P
B Here, KooN is a constant, and KTA is an intake air temperature correction coefficient that is set to increase as the intake air temperature decreases.

As described above, when the basic fuel injection amount Tp is calculated based on the intake air flow rate Q detected by the air flow meter 13 or the intake pressure PB detected by the intake pressure sensor, in the next step 56, this basic fuel injection amount is calculated using the following equation. A final fuel injection amount Ti is calculated by correcting Tp.

T i <-T p X (α+KBLRC) XC0
EF+Ts Here, C0EF is various correction coefficients based on engine operating conditions such as engine cooling water temperature, and Ts is a correction factor based on battery voltage.

A drive pulse signal having a pulse width corresponding to the fuel injection amount Ti calculated as described above is output to the fuel injection valve 6 at a predetermined injection timing, and fuel corresponding to Ti is injected and supplied to the engine 1.

<Effects of the Invention> As described above, according to the present invention, in the air-fuel ratio control device configured to set a feedback correction coefficient based on the deviation of the air-fuel ratio from the target air-fuel ratio and the differential value of the change in the air-fuel ratio, Calculating the differential value at every predetermined minute time, and
Since the feedback correction coefficient is set at every predetermined minute time using the differential value, the differential value can be accurately determined without being affected by the engine speed, and this allows air-fuel ratio feedback control using the feedback correction coefficient. This has the effect of improving the accuracy of the air-fuel ratio and improving the degree of convergence to the target air-fuel ratio.

[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 present invention, and Fig. 3 shows the output characteristics of an oxygen sensor as an air-fuel ratio detection means in the same embodiment. Graphs 4 to 6 are flowcharts showing the control routine in the above embodiment, FIG. 7 is a time chart for explaining conventional feedback control characteristics, and FIG. 8 is for explaining problems in conventional control. This is a time chart for 1... Engine 6... Fuel injection valve 12... Control unit 13... Air flow meter 1
4...Crank angle sensor 15...Water temperature sensor 1
6...Oxygen sensor patent applicant Fujio Sasashima, agent of Japan Electronics Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] An engine operating state detection means for detecting an engine operating state; a basic fuel injection amount setting means for setting a basic fuel injection amount based on the engine operating state detected by the engine operating state detection means; air-fuel ratio detection means for detecting exhaust components and thereby detecting the air-fuel ratio of the air-fuel mixture taken into the engine; deviation calculation means for calculating the deviation of the detected air-fuel ratio from a target air-fuel ratio; a time-synchronized differential value calculating means for calculating a differential value of a fuel ratio at every predetermined minute time; and a feedback correction coefficient for feedback correcting the basic fuel injection amount based on the deviation and the differential value at every predetermined minute time. Fuel injection that calculates a fuel injection amount based on a time synchronized feedback correction coefficient setting means, a basic fuel injection amount set by the basic fuel injection amount setting means, and a feedback correction coefficient set by the feedback correction coefficient setting means. An air conditioner for an internal combustion engine characterized by comprising: a quantity calculation means; and a fuel injection means for injecting and supplying fuel to the engine on and off based on a drive pulse signal corresponding to the calculated fuel injection quantity. Fuel ratio control device.