JPH0830441B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine such as an automobile, and more particularly to a fuel supply device for calculating a fuel supply amount based on an intake air amount.

[0002]

2. Description of the Related Art Recently, demands for internal combustion engines such as automobiles have become more sophisticated, and there is a tendency to achieve high levels of conflicting problems such as reduction of harmful exhaust gas, high output, and low fuel consumption. It is in. Further, such a requirement is the same for the wall flow correction, and it is desired to improve the accuracy of the wall flow correction.

In the conventional fuel supply control device of this type, the required load per unit revolution of the engine is obtained from the output of the air flow meter provided on the upstream side of the throttle valve, and the fuel injection amount per unit revolution is calculated from this. . Further, at the time of transition, it is dealt with by correcting the fuel injection amount (see, for example, Japanese Patent Laid-Open No. 59-538). However, in the conventional device, an appropriate injection amount calculation considering the capacity of the intake pipe between the mounting position of the air flow meter and the mounting position of the injection valve (injector), that is, the intake volume, is not performed, and the transient time However, there is a problem that the injection performance of the engine is delayed from the required characteristics of the engine and the driving performance is poor.

In order to solve such a problem, improvement is aimed at.
For example, see Japanese Patent Application Laid-Open No. 60-162066.
The ones listed here (also referred to simply as prior applications in the following explanation)
It With this device, the actual intake air flowing into the cylinder
The amount changes with a first-order lag response to changes in engine speed.
This causes changes in the set air-fuel ratio and a delay in the generated torque response.
The output of the air flow meter is smoothed with a first-order lag in order to accurately obtain the amount of air flowing through the injection valve , and the fuel injection amount is based on the smoothed amount of air.
Fuel injection by calculating (fuel injection amount equivalent to cylinder air amount)
It is in control. Note that fuel injection equivalent to cylinder air amount
The injection amount is predetermined as the pulse width AvTp equivalent to the cylinder air amount.
It is calculated by the calculation method.

[0005]

The object of the invention is to, however, this
In such devices, the output of the air flow meter is delayed
What is smoothed by this to perform transient correction of air amount
Of the so-called wall flow
Therefore, for example, in the case of a vehicle that performs fuel cut, the air-fuel ratio immediately after the fuel cut is released (during recovery) is the target value (for example, the theoretical air-fuel ratio in which the excess air ratio λ is λ = 1).
It takes a long time to return to the ratio , and exhaust emission characteristics and drivability may be deteriorated (a breathing phenomenon may occur).

Therefore, the present invention is directed to such a fuel cell.
The purpose is to improve the exhaust characteristics and drivability by making the asynchronous injection determination and the injection amount at the time of lean appropriate so as to avoid the adverse effect of the engine.

[0007]

To achieve the above object, the present invention is synchronized with the fuel injection valve provided in the intake pipe and the combustion cycle of each cylinder, as shown in the basic conceptual diagram of FIG. An internal combustion engine including: a fuel injection valve control device that controls the fuel injection valve to perform fuel synchronous injection for each cylinder at a timing and to perform fuel asynchronous injection at a timing different from the timing under a predetermined condition. Fuel supply control device, at least the throttle valve opening degree
And the engine speed, and the output value of the operating condition detection means a was calculated from the throttle valve opening and the engine speed.
The change in throttle valve opening based on the amount of change in the air flow rate is anticipated in advance.
In addition to the above correction, the cylinder air amount equivalent fuel injection amount calculation means b for calculating the cylinder air amount equivalent fuel injection amount (AvTp) corresponding to the air amount taken into the cylinder, and the previous fuel injection for each cylinder. A storage means c for storing the cylinder air amount equivalent fuel injection amount (AvTpoin) at each timing as a storage value for each cylinder, the current cylinder air amount equivalent fuel injection amount (AvTp) for each cylinder, and the previous fuel injection timing. Cylinder air equivalent fuel injection amount (A
cylinder air amount equivalent fuel injection amount difference value calculating means d for calculating a difference value (AvTp-AvTpoin) from vTpoin),
Fuel cut start / end determining means e that determines the start and end of fuel cut based on the output of the operating state detection means a; and the stored value (AvTp) during fuel cut.
memory value updating means f for updating the memory value (AvTpoin) for each cylinder in synchronism with the combustion cycle of each cylinder so that (oin) is gradually decreased, and the final fuel injection amount is set to zero during fuel cut. On the other hand, when the fuel cut is not in progress, the synchronous injection amount calculation means g for calculating the fuel synchronous injection amount based on the magnitude of the difference value (AvTp-AvTpoin) and the difference value (AvTp-AvTpoin) are predetermined values. When it is larger, the difference value (AvTp-AvTpoin)
Asynchronous injection amount calculation means h for calculating the asynchronous fuel injection amount based on the magnitude of

[0008]

According to the present invention, the final fuel injection amount is set to zero during the fuel cut, while the fuel injection amount (AvTp) corresponding to the current cylinder air amount for each cylinder and the previous fuel injection are performed during the fuel cut. The fuel synchronous injection amount is calculated based on the magnitude of the difference value (AvTp-AvTpoin) from the cylinder air amount equivalent fuel injection amount (AvTpoin) at the timing, and when the difference value is larger than the predetermined value,
The fuel asynchronous injection amount is calculated based on the magnitude.
Here, the fuel injection amount (AvT
In p), the correction term of delay correction pulse width is
Added as a pre-correction for changes in air volume due to
Has been. That is, at the time of recovery, the difference value (AvT
Asynchronous injection determination is made by comparing p-AvTpoin) with the predetermined value (small recovery reference value), and the recovery amount is determined. Also, the delay correction pulse width is
The fuel injection amount by anticipating changes in the opening of the throttle valve that controls the fuel injection amount.
Corrects with good responsiveness. Therefore, in response to fuel transfer delay after the change and the injection of the cylinder intake air quantity (the influence of wall flow) This will allow for some to perform asynchronous injection and the synchronous injection suitable amount without delay at the appropriate time, Actual air volume change
It will be the one that matches.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 2 to 7 are views showing an embodiment of a fuel supply control device for an internal combustion engine according to the present invention. First, the configuration will be described. Figure 2
FIG. 3 is a diagram showing an overall configuration of this device.

In FIG. 2, reference numeral 1 denotes an engine, intake air passes from an air cleaner 2 to an intake pipe 3, and fuel is injected from an injector (fuel injection means) 4 based on an injection signal Si. The exhaust gas burned in the cylinder is the exhaust pipe 5.
Is introduced into the catalytic converter 6 through the catalytic converter 6 and the harmful components (CO, HC, NOx) in the exhaust gas are cleaned by the three-way catalyst and discharged.

The flow rate Qa of the intake air is detected by a hot wire type air flow meter 7, and a throttle valve 8 in the intake pipe 3 is detected.
Controlled by. The type of the air flow meter 7 may be a hot film type, and any type that measures the flow rate of intake air may be used. Therefore, a flap type or a negative pressure sensor may be used. Throttle 8
The opening degree TVO of the engine is detected by the throttle opening sensor 9, and the rotation speed N of the engine 1 is detected by the crank angle sensor 10. In addition, the temperature T of the cooling water flowing through the water jacket
w is detected by the water temperature sensor 11, and the oxygen concentration in the exhaust gas is detected by the oxygen sensor 12. As the oxygen sensor 12, a sensor having a characteristic that the output Vs of the stoichiometric air-fuel ratio changes abruptly is used. Further, the idle state of the engine 1 is detected by the idle switch 13.

The air flow meter 7, throttle valve opening sensor 9, crank angle sensor 10, water temperature sensor 11, oxygen sensor 12
Also, the idle switch 13 constitutes an operating state detecting means 14, and the output of the operating state detecting means 14 is input to the control unit 20. The control unit 20 is a book
Cylinder air amount equivalent fuel injection amount calculator in the invention of application
Stage, storage means, cylinder air amount equivalent fuel injection amount difference value calculation
Means, fuel cut start / end determination means, stored value update hands
Stage, synchronous injection amount calculation means and asynchronous injection calculation means
It has all the functions of CPU21, ROM22, RAM23
And I / O port 24. CPU21
I according to the program written in ROM22
While fetching necessary external data from the / O port 24 and exchanging data with the RAM 23
Cylinder air corresponding to fuel injection amount equivalent to cylinder air amount
Amount equivalent pulse width AvTp and other processing values required for injection control
(Described later) is arithmetically processed, and the processed data is output to the I / O port 24 as necessary. Signals from the sensor groups 7 and 14 are input to the I / O port 24, and I / O
The injection signal Si is output from the port 24. The ROM 22 stores an arithmetic program in the CPU 21, and RA
M23 stores the data used for the calculation in the form of a map or the like.

Pulse width AvTp corresponding to the cylinder air amount
Smooths the output of the air flow meter 7 with a first-order delay and absorbs it.
It is obtained by performing transient correction of the amount of incoming air.
It can contribute to the stabilization of the ratio. Also, the CPU 21
This cylinder air amount equivalent pulse width AvTp calculation result
Based on this, the asynchronous injection is determined by the following equation. AvTp-AvTpoin ≥LASNI ... where LASNI is a cylinder-specific asynchronous injection determination value
(Hereinafter, simply referred to as a threshold), AvTpoin is
The last injection timing with the nth injection valve (injector)
Cylinder air amount equivalent pulse width AvT used for injection
It is the value of p. AvTp-AvTpoin is
Later, it is also simply referred to as a difference value.

Next, the operation will be described. The main program of this embodiment is shown in FIG. 5, but for convenience of explanation,
First, the subroutine for obtaining the pulse width (cylinder air amount equivalent fuel injection amount) AvTp corresponding to the cylinder air amount shown in FIG. 3 will be described. Further, the description will be given based on the control waveform of FIG.

As shown in FIG. 3, in this subroutine, first, in step P ₁ , the output of the air flow meter 7 is read to obtain the intake air amount Qa. This is for example by table lookup. Next, in step P ₂ , the basic pulse width Tp ₀ before smoothing is calculated according to the following equation. Tp ₀ = (Qa / N) × K ...... where N is the engine speed, K is the proportional constant, and Qa is the intake air.
It is a generous amount

Next, in step P ₃ , the basic pulse width Tp ₀ before smoothing is weighted and averaged to calculate the basic pulse width Tp, and then in step P ₄ , the flat corrected basic pulse width TrTp is obtained according to the following equation. As a result, the pulsation based on the output of the air flow meter 7 is smoothed. TrTp = Tp × Kflat In the equation, Kflat is a flat A / F (air-fuel ratio) correction coefficient, and is calculated with interpolation calculation from a map allocated by the rotation speed N and an α-N flow rate Qho described later. The α-N flow rate is an air flow rate obtained from the throttle valve opening TVO and the engine speed N, and is already known.

Next, in step P ₅ , the flat correction basic pulse width TrTp is compared with a predetermined maximum limit value Tp _max . If TrTp> Tp _max , then in step P ₆ the flat correction basic pulse width TrTp is changed to the maximum limit value Tp.
Limit to _max and proceed to step P ₇ , TrTp ≦ Tp
_{If max} , jump to step P ₆ and skip to step P _7.
Proceed to. In step P ₇ , the delay correction pulse width THSTP as the α-N pre-correction pulse width is obtained. This delay correction pulse width THSTP is for correcting the injection amount with good responsiveness by anticipating the change in the opening degree of the throttle valve 8. The α-N flow rate Q
The value is calculated as the amount of change of the value TTHSTP that is looked up from the table with interpolation calculation based on ho every 10 ms. However,
If the amount of change is equal to or lower than the correction determination level, THSTP
= 0, and when the amount of change is negative (deceleration), the amount of change is multiplied by a predetermined deceleration correction rate.

Then, in step P ₈ , the system is calculated according to the following equation.
Cylinder air as pulse width AvTp equivalent to Linda air amount
The fuel injection amount corresponding to the amount is calculated. AvTp = TrTp × FLOAD ÷ AvTp ₋₁ × (1-
FLOAD) + THSTP ... In the formula, FLOAD is a weighted average coefficient, and FL
It is given by an arithmetic expression of OAD = TFLOAD + K2D (deceleration only). TFLOAD is a function of only the intake volume, and is obtained by a map from the flow passage area AA of the throttle valve 8 and [displacement amount × rotation speed] NVM. Therefore,
The first and second terms of the equation are the weighted average values using FLOAD for the flat corrected basic pulse width TrTp calculated based on the pulsation corrected value of the output of the air flow meter 7, in other words, the first-order lag of TrTp is calculated. It corresponds to the part calculated by (by software). Further, the third term of the equation is a portion for pre-correction by the throttle valve opening TVO, and this portion is not disclosed in the prior application and is disclosed for the first time in this embodiment.

The delay correction pulse width TH of the third term is
The effect of adding STP is shown in FIG. In FIG. 4, when acceleration is performed at a certain timing, the basic pulse widths Tp ₀ and Tp change with a slight delay after the change in the throttle opening,
The waveform obtained by correcting p ₀ and Tp changes as the flat correction basic pulse width TrTp as shown in FIG. On the other hand, the α-N flow rate Qho changes stepwise according to the opening degree of the throttle valve 8, and the delay correction pulse width THS is changed by this opening change amount.
TP is calculated. The cylinder air amount equivalent pulse width AvTp is given with a first-order delay of the flat correction basic pulse width TrTp.

In the case of the conventional phase control without the delay correction pulse width THSTP, the change is shown by the alternate long and short dash line in the figure and the response is lacking. At this time, the suction negative pressure is indicated by a broken line and is substantially equal to the air flow rate of the injection valve portion (the injector 4 portion), but cannot follow the change in the opening degree of the throttle valve 8 without delay. Further, the intake volume also affects the amount of fuel adhering to the wall surface of the intake pipe 3. Therefore, Siri
The air-fuel ratio equivalent pulse width AvTp is for stabilizing the air-fuel ratio.
Although it contributes, the determination of recovery is based on the above formula.
Just doing it will make the asynchronous injection amount during recovery inappropriate.
May be. Also, the injection at the previous injection timing
Cylinder air amount equivalent pulse width AvTp value (A
vTpoin) is just before the start of fuel cut
It is the fuel injection amount equivalent to the cylinder air amount and is taken by the wall flow
It also includes fuel. On the other hand, the wall during fuel cut
The flow is gradually removed (sucked into the cylinder),
It is possible that there is almost no wall flow during recovery.
In the previous application, a fue called AvTPoin despite recovery
Since the parameters that are unrelated to Lecat are used, the injection amount during recovery is actually insufficient and the air-fuel ratio does not reach the target value.

On the other hand, in the cylinder air amount equivalent pulse width AvTp of the present embodiment, as shown by the solid line in the figure, the correction term for the delay correction pulse width THSTP is the pre-correction of the α-N flow rate (pre-correction of 10 ms). Therefore, the response is extremely good and it matches the actual change in the air flow rate. An example in the highlands is also shown. FIG. 5 is a flowchart showing a program for calculating the recovery reference value. This program is executed at each injection timing of each cylinder.
It is executed in the interrupt. First, in step P ₁₁ , the injection cylinder of this time is determined, and in step P ₁₂ , it is determined whether or not fuel cut is in progress. Cylinder air amount equivalent pulse width AvTp preceding fuel injection Timing of this injection cylinder in Step P ₁₃ (represented by n-th) when not in fuel cut
Corresponding to the cylinder injection amount fuel injection amount
It is stored in the RAM 23 as a stored value AvTpoin.

Therefore, when the fuel cut is not in progress, the asynchronous injection interrupt processing is performed based on the pulse width AvTp corresponding to the cylinder air amount (the program is not shown), but as described above, it corresponds to the cylinder air amount shown in the equation. The pulse width AvTp itself considers the wall flow amount, and the cylinder inflow fuel amount becomes appropriate. On the other hand, if the fuel cut is in progress, proceed to Step P ₁₄ and perform the previous fuel injection.
Description of pulse width equivalent to cylinder air amount at injection timing
The memorized value AvTpoin is gradually reduced by the following formula.
To update .

[0023] AvTpoin = AvTpoin -T _PFC ...
Here, T _PFC is a predetermined subtraction value (constant value). Engine speed is high immediately after the fuel cut start, since come gradually decreases with time, the calculation of the equation to be executed in rotation synchronization, AvTpoin -T _PFC (= the current AvTpoin) is 6 As shown, from the start of fuel cut, with the lapse of time due to the repetition of this program, it initially decreases rapidly, but the decreasing rate gradually decreases,
Eventually it will be almost zero. This corresponds to the state in which the wall flow amount remaining in the intake pipe 3 decreases from the start of fuel cut.

FIG. 7 shows a timing chart during the fuel cut. In the figure, before reaching the fuel cut, the final injection amount Ti is calculated according to the following equation based on the cylinder air amount equivalent pulse width AvTp. Ti = (AvTp + Kathos) × Tfbya × (α + α
m) + Ts ... In the formula, Kathos has positive and negative values of the wall flow correction pulse width, and the fuel adhesion speed Vmf (ms) and the correction rate Ghf (%)
Given by the function. Tfbya is the target air-fuel ratio. α
Is a λ control correction coefficient for the air-fuel ratio based on the output of the oxygen sensor 12, and αm is a mixture ratio learning control correction coefficient. Ts is an invalid pulse width.

In the figure, when the throttle valve 8 shifts to the fully closed state, the cylinder air amount equivalent pulse width AvTp decreases from the fully closed state of the throttle valve 8 to the minimum. And of the throttle valve 8
It is judged that the fuel cut has started after a predetermined time has passed since the valve was fully closed.
Fuel supply for both synchronous and asynchronous injection is prohibited
To be done. As a result, the air-fuel ratio rapidly increases, and when the exhaust pipe 5 becomes the atmosphere, the air-fuel ratio A / F = ∞. Also,
The torque also suddenly decreases, and the vehicle runs with the inertial force during fuel cut.

Further, during the fuel cut, the stored value AvTpoin is calculated by the above expression, the value becomes smaller with the lapse of time, and finally reaches the minimum limit value.
That is, the final fuel injection amount during fuel cut is zero.
Set to (zero). The driver depresses the accelerator pedal
As soon as the throttle valve 8 is no longer fully closed,
End is determined, both synchronous and asynchronous injection
The prohibition on fuel supply is lifted.

Then, at the time of recovery, it is first determined whether or not the asynchronous injection accompanying the recovery is performed according to the above formula. In this case, the stored value AvTpoin is the actual wall flow.
It gradually becomes smaller to reflect the decrease in
Pulse width AvTp and stored value AvTpoin
Difference becomes large, and asynchronous injection is performed promptly during recovery.
Judgment is made and the asynchronous injection with excellent responsiveness is not delayed.
You can do it. For the same reason, the cylinder
Air amount equivalent pulse width AvTp and the stored value Av Tpoin
Difference becomes larger and the difference value (AvTp-AvTpoin
7), the recovery injection amount is calculated, so that the air-fuel ratio quickly shifts to the target value and the torque during recovery immediately recovers in this embodiment as shown in FIG.

Specifically, in (a) in the figure, the difference value (A
Since vTp-AvTpoin) greatly exceeds the predetermined threshold value LASNI, sufficient asynchronous injection is executed according to the magnitude of this difference value. Further, in (b) of the figure, since the synchronous injection timing has been reached, a new difference value (AvTp-AvTpoin) is calculated using AvTpoin stored at the injection timing of the previous injection, and the synchronous injection corresponding to the value is calculated. To be executed. After that, when the intake air amount into the cylinder increases and the cylinder air amount equivalent pulse width AvTp increases, the difference value (AvTp-AvTp
oin) exceeds a predetermined threshold LASNI ,
In (c), the asynchronous injection is executed. When the increase rate of the intake air amount becomes gentle, the difference value (AvTp-A
Synchronous injection timing comes before vTpoin) exceeds the threshold value, and AvTpoin is newly changed by the synchronous injection. After that, only synchronous injection and synchronous injection are executed.

As described above, in this embodiment, the final fuel injection amount is set to zero during the fuel cut, while the fuel injection amount of the throttle valve, which is obtained as the cylinder air amount equivalent pulse width AvTp, is set during the fuel cut . Due to change
The current cylinder air amount equivalent fuel injection amount and stored value AvT for each cylinder, which takes into account advance correction for changes in the air flow rate.
poin, that is, the difference value (AvTp-AvT) from the fuel injection amount corresponding to the cylinder air amount at the previous fuel injection timing.
The fuel synchronous injection amount is calculated based on the magnitude of the point, and when the difference value is larger than a predetermined value, the fuel asynchronous injection amount is calculated based on the magnitude. Therefore, it becomes possible to perform an appropriate amount of asynchronous injection and synchronous injection at an appropriate time without delay in response to a change in the cylinder intake air amount and a fuel transport delay (influence of wall flow) after injection.
The air-fuel ratio during acceleration can be controlled as desired. As a result, for example, it is possible to suppress exhaust emission due to a deviation from the three-way point of the three-way catalyst (excess air ratio λ = 1) and improve exhaust gas purification performance, and improve drivability (improvement of response and breath). Prevention).

Further , in this embodiment, the injection amount for each cylinder is
Cylinder air amount equivalent pulse for the previous injection of the cylinder
For each cylinder based on the amount of increase in the width (memory value AvTpoin)
Since it is designed to
Despite the combustion cycle period in
For changes in driving conditions during a period that exactly matches this period
A corresponding amount of fuel can be supplied to the injector 4.
The air-fuel ratio A / F can be optimally set for each cylinder.
It

Further, in this embodiment, during fuel cut
And the stored value AvTp in synchronization with the fuel injection timing.
I updated the oin so that I could decrease it.
The operating conditions during the set-up period, such as rotation speed and length of time.
Instead, as shown in Figure 7, an appropriate amount at an appropriate time (early)
Asynchronous injection or synchronous injection (by increasing the amount) of
And improve emissions and driveability during recovery
Can be.

The reduction rate of the stored value AvTpoin
Is changed by the data of the cooling water temperature Tw
Good.

[0033]

According to the present invention, an appropriate amount of asynchronous injection and synchronous injection can be performed at an appropriate time without delay in response to a change in cylinder intake air amount and a fuel transport delay after injection (effect of wall flow). Therefore, the air-fuel ratio during acceleration can be controlled as desired, and the exhaust gas purification performance can be improved and the breath can be prevented. Also, delay correction
The pulse width is corrected in advance in response to changes in the throttle opening.
Since the injection amount for each cylinder is calculated for each cylinder based on the increase amount of the fuel injection amount corresponding to the cylinder air amount with respect to the previous injection of the cylinder, it is possible to change the operating state during the combustion cycle period for each cylinder. A corresponding amount of fuel can be supplied to the fuel injection valve, and the air-fuel ratio can be optimally set for each cylinder. Furthermore, during fuel cut, the stored value of the previous injection amount is updated and decreased in synchronization with the fuel injection timing, so regardless of the operating state during the fuel cut period, an appropriate amount of fuel can be used at an appropriate time. Asynchronous injection and synchronous injection can be performed, and exhaust emission and recoverability during recovery can be improved.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of a fuel supply control device for an internal combustion engine according to the present invention.

FIG. 3 is a flowchart of a subroutine for calculating a pulse width corresponding to the cylinder air amount.

FIG. 4 is a timing chart illustrating an operation based on a smooth supply amount.

FIG. 5 is a flowchart showing a main program for calculating the injection amount.

FIG. 6 is a diagram showing a tendency of the stored value AvTpoin.

FIG. 7 is a timing chart explaining the operation during the fuel cut.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine 4 injector (fuel injection means) 7 air flow meter (intake air amount detection means) 14 operating state detection means 20 control unit ( cylinder air amount equivalent fuel injection amount calculation means, storage means,
Cylinder air amount-phase equivalent fuel injection amount difference value calculating means, fuel
Cut start / end determination means, stored value update means, synchronous injection amount
Calculation means and asynchronous injection calculation means)

Claims (1)

[Claims] 1. A fuel injection valve provided in an intake pipe, and a fuel synchronous injection is executed for each cylinder at a timing synchronized with a combustion cycle of each cylinder. A fuel supply control device for an internal combustion engine, comprising: a fuel injection valve control device for controlling the fuel injection valve so that asynchronous injection is executed; a) operation state detection including at least a throttle valve opening and an engine speed. Means, and b) the output value of the operating state detecting means , the throttle opening and the engine speed.
Change of throttle valve opening based on the amount of change in air flow obtained from
The fuel injection amount (AvT) corresponding to the cylinder air amount corresponding to the air amount taken into the cylinder (AvT
c) a cylinder air amount equivalent fuel injection amount calculation means for calculating p), and c) a storage means for storing for each cylinder the cylinder air amount equivalent fuel injection amount (AvTpoin) at the previous fuel injection timing for each cylinder as a storage value. D) For each cylinder, a difference value (AvTp-AvTpoin) between the current cylinder air amount equivalent fuel injection amount (AvTp) and the cylinder air amount equivalent fuel injection amount at the previous fuel injection timing (AvTpoin) is calculated. Cylinder air amount equivalent fuel injection amount difference value calculation means, and e) Fuel cut start / end determination means for determining start and end of fuel cut based on the output of the operating state detection means, and f) During fuel cut, Memory value (AvTpoin)
So as to gradually decrease, the memory value updating means for updating the memory value (AvTpoin) for each cylinder in synchronization with the combustion cycle of each cylinder, and g) setting the final fuel injection amount to zero during the fuel cut. On the other hand, when the fuel cut is not in progress, the difference value (A
vTp-AvTpoin), a synchronous injection amount calculating means for calculating a fuel synchronous injection amount based on the magnitude of (vTp-AvTpoin), and h) If the difference value (AvTp-AvTpoin) is larger than a predetermined value, the difference value (AvTp-AvTpoin). The fuel supply control device for an internal combustion engine, comprising: an asynchronous injection amount calculation means for calculating a fuel asynchronous injection amount based on the size of the above.