JPH0610437B2 - Control method of fuel control device of electronic fuel injection engine - Google Patents

Description

The present invention relates to a so-called L-Jetronic method when the engine load is smaller than a predetermined value, and a so-called D-type when the engine load is larger than a predetermined value. The present invention relates to an improvement in a fuel control method for an electronic fuel injection type engine that controls a fuel injection amount by a Jettronic system, and more particularly, to such a system provided with means for controlling a fuel injection amount by a transient detection signal. The present invention relates to a control method of a fuel control device for an electronic fuel injection type engine.

2. Description of the Related Art As a control device for an electronic fuel injection engine, a so-called L-Jetronic system (hereinafter, L-J) is generally used.
It is called a method. ) And D-Jetronic system (hereinafter D
-It is called J method. ) Two types of methods are known.

The LJ method determines the fuel injection amount that gives the optimum air-fuel ratio according to the engine operating state based on the detection output signal of the air flow sensor provided in the intake pipe upstream of the throttle valve and the detection output signal of the engine speed detector. It is a method of controlling the valve opening time of the fuel injection valve so that the fuel is injected with this fuel injection amount. The air flow sensor generally used in this system includes a dynamic pressure measurement plate rotatably mounted in the intake pipe and a spring for urging the plate to oppose the air flow, and the intake air flow pressure The intake air amount is detected by the displacement angle of the corresponding plate. For example, the intake air amount in the full output operation state of the engine is generally about 5 in the idle operation state.
Since the intake air amount generally fluctuates greatly, such as reaching 0 times, it is difficult to detect the intake air amount with high accuracy by the displacement angle of one dynamic pressure measuring plate as described above. There was a problem that was.

On the other hand, the DJ method detects the pressure in the intake pipe and the engine speed, obtains the intake air amount per engine revolution based on these detection signals, and gives an optimum air-fuel ratio according to the engine operating state. This is a method of calculating the amount and controlling the opening time of the fuel injection valve so that the fuel is injected with this fuel injection amount. This method focuses on the fact that the intake air amount is approximately proportional to the intake pipe internal pressure when the engine speed is constant, and the basic fuel injection for the intake air amount corresponding to the intake pipe internal pressure is stored in the memory of the fuel control circuit in advance. The amount is stored, and the basic fuel injection amount is corrected based on the engine speed to determine the fuel injection amount. However, when the correction is performed based on the engine speed, in the low speed region, There is a problem in that the desired fuel injection amount cannot be calculated with high accuracy because the correction coefficient greatly varies. That is, even if the intake pipe internal pressure and the engine speed are determined, the calculated intake air amount deviates from a desired value due to the engine operating state, the outside air condition, etc., and the deviation amount tends to be large particularly in the low rotation load region. However, the DJ method has a problem that the air-fuel ratio control accuracy is poor in the low rotation and low load region.

In order to compensate for the disadvantages of the L-J system and the D-J system and utilize their advantages, the L-J system is used when the intake air amount is less than a predetermined amount, and the D-method is used when the intake air amount is more than the predetermined intake air amount.
A control device for an electronic fuel injection type engine that controls a fuel injection amount by the -J method is proposed in Japanese Patent Publication No. 59-7017. According to this method, there is an advantage that the fuel injection amount that gives the optimum air-fuel ratio with respect to a wide range of intake air amount fluctuations can be accurately calculated and controlled.

Problems to be Solved by the Invention However, in the electronic fuel injection amount type engine control device disclosed in Japanese Patent Publication No. 59-7017, the fuel injection amount is controlled so as to provide an optimum air-fuel ratio during transient of the engine. It was impossible to do. That is,
During a transient period, the fuel injection amount control system inevitably has a response delay, so the fuel injection amount to be injected at a certain time is controlled to a value calculated based on the engine operating state at a time earlier than that. Inevitably, therefore, there is a problem that the fuel injection amount cannot be controlled to give the optimum air-fuel ratio during the transition.

Although such a problem can be solved by detecting a transient state and correcting the fuel injection amount calculated by the method that should be selected in the operating state, it is possible to solve the change in the operating state transiently. Accordingly, when the calculation method of the fuel injection amount changes between the LJ method and the DJ method, the fuel injection amounts calculated by the LJ method and the DJ method are different, and further, Since the correction value of the fuel injection amount in the same transient state is also different between the L-J method and the DJ method, simply correcting the fuel injection amount calculated by the method to be selected at the transition time, There is a problem in that it is impossible to prevent a discontinuous and sudden change in the fuel injection amount.

OBJECT OF THE INVENTION The present invention provides a fuel injection amount calculation method in an L-J method and a D-method in a transient state where the operating state of an engine is changing.
An object of the present invention is to provide a control method of a fuel control device for an electronic injection type engine, which can control the fuel injection amount so as to give an optimum air-fuel ratio even when it is necessary to switch to the J system. It is a thing.

Configuration of the Invention An object of the present invention is to provide an air flow meter for detecting an intake air amount provided in an intake system, a load detection means for outputting a signal corresponding to an intake negative pressure downstream of a throttle valve, and an engine speed detection. And an engine rotation speed detection means for calculating the basic fuel injection quantity by the LJ method based on the output of the air flow meter, the load detection means, and the engine rotation speed detection means. In the operating range where the intake air amount or the engine load exceeds a predetermined value, the D-J system fuel injection amount calculation means for calculating the basic fuel injection amount by the D-J system based on the output of
The basic fuel injection amount calculated by the -J method fuel injection amount calculation means is selected, and in the operating region where the intake air amount or the engine load is equal to or less than a predetermined value, the basic fuel injection amount calculated by the LJ method fuel injection amount calculation means is selected. Basic fuel injection amount selection means for selecting the fuel injection amount, and operating states are an operating state in which the basic fuel injection amount should be calculated by the LJ method and an operating state in which the basic fuel injection amount should be calculated by the DJ method. It is determined whether or not there is a change, and when it is determined that there is a change, a switching determination unit that outputs a switching signal, a transient detection unit that detects an engine transient time, and a transient detection signal of the transient detection unit. On the basis of the above, a transient correction value for correcting the basic fuel injection amount calculated by the LJ method fuel injection amount calculation means and the basic fuel injection amount calculated by the DJ method fuel injection amount calculation means are calculated. In the control method of the fuel control device for the electronic injection engine, the basic fuel injection amount selection means includes the transient fuel injection amount correction value calculation means and the basic fuel injection amount. Based on the output signals from the selection means and the switching determination means,
When the switching signal is not input from the switching determination unit, the basic fuel injection amount input from the basic fuel injection amount selection unit is input from the transient fuel injection amount correction value calculation unit according to the operating state at that time. On the other hand, when the switching signal is input from the switching determination means, the basic fuel injection amount calculated according to the method used before the input of the switching signal is used for a predetermined time. After that, the basic fuel injection amount input from the basic fuel injection amount selection means is gradually switched to the value of the fuel injection amount corrected by the transient correction value input from the transient fuel injection amount correction value calculation means. Thus, the fuel injection amount correction means for executing the switching calculation of the basic fuel injection amount and outputting the fuel injection control signal to the fuel injection control means for controlling the fuel injection valve is provided. When the switching signal is input from the switching means before the completion of the switching calculation, the fuel injection amount correction means calculates the value of the basic fuel injection amount calculated according to the method used before the input of the switching signal. From the above, after the predetermined time, the basic fuel injection amount input from the basic fuel injection amount selection means is converted into the value of the fuel injection amount corrected by the transient correction value input from the transient fuel injection amount correction value calculation means. The control method of the fuel control apparatus for the electronic fuel injection type engine is characterized in that the switching calculation of the basic fuel injection amount is executed again so as to switch gradually.

EFFECTS OF THE INVENTION According to the present invention, the operating state of the engine changes, and L-
The operating state in which the fuel injection amount should be calculated by the J method and D-
In the transitional state that has changed between the operating state in which the fuel injection amount should be calculated by the J method, before the operating state changes, from the basic fuel injection amount calculated by the method used to calculate the fuel injection amount, Under the operating condition at the time point, the basic fuel injection amount to be selected is gradually changed to the fuel injection amount corrected based on the transient correction value calculated in the operating condition after a predetermined time has elapsed. Since the switching calculation is executed, the operating state of the engine changes, and the operating state in which the fuel injection amount should be calculated by the L-J method and the operating state in which the fuel injection amount should be calculated by the D-J method. It is possible to prevent a discontinuous and sudden change in the fuel injection amount caused by a different calculation method of the basic fuel injection amount and the transient correction value in the transient state that changes between the two. The operating state changes between an operating state in which the fuel injection amount should be calculated by the L-J method and an operating state in which the fuel injection amount should be calculated by the DJ method, and again during execution of the switching calculation, When the operating state in which the fuel injection amount should be calculated by another method is changed, the same switching calculation is executed again, so that in the transient state,
It is possible to reliably prevent discontinuous and abrupt changes in the fuel injection amount caused by different calculation methods of the basic fuel injection amount and the transient correction value.

Example Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention. The engine 1 includes a piston 3 that reciprocates in a cylinder bore 2, and a space above the piston 3 of the cylinder bore 2 constitutes a combustion chamber 4. An intake port 5 and an exhaust port 6 are opened in the combustion chamber 4, and an intake valve 7 and an exhaust valve 8 are combined with the intake port 5 and the exhaust port 6, respectively. An intake passage 9 and an exhaust passage 10 are connected to the intake port 5 and the exhaust port 6, respectively. An air cleaner 11 is installed at an upstream end of the intake passage 9, an air flow meter 12 is provided in the intake passage 9 downstream of the air cleaner 11, a throttle valve 13 is provided downstream of the air flow meter 12, and a throttle valve 13 is further provided. Fuel injection valves 14 are provided downstream of the respective fuel cells 13.

An air-fuel ratio sensor 15 for detecting the oxygen concentration in the exhaust gas and controlling the air-fuel ratio is attached to the exhaust passage 10.

In the fuel supply system of the engine of this embodiment, the fuel is introduced from the fuel tank 16 into the fuel pump 17, adjusted through the fuel filter 18 by the fuel pressure regulator 19 to a predetermined pressure, and then sent to the fuel injection valve 14. In this embodiment, in order to control the fuel injection amount so as to obtain the optimum air-fuel ratio, the fuel injection amount control device 20 preferably including a microcomputer is provided. The fuel injection amount control device 20 detects a signal indicating the opening degree θ of the throttle valve 13, an intake pipe internal pressure detection signal from an intake pipe internal pressure sensor 21 provided in the intake pipe downstream of the throttle valve 13, and an engine speed. The crank angle signal from the crank angle sensor 22 and the oxygen concentration signal from the air-fuel ratio sensor 15 are input, and the fuel injection amount control device 20
These input signals are calculated to calculate the fuel injection amount that gives the optimum air-fuel ratio, and the valve opening time of the fuel injection valve 14 is controlled.

FIG. 2 is a block diagram of the fuel injection amount control device 20 according to the embodiment of the present invention.

The fuel injection amount control device 20 shown in FIG. 2 includes intake air amount detecting means such as the air flow meter 12, engine speed detecting means such as the crank angle sensor 22, and intake pipe internal pressure detection such as the intake pipe internal pressure sensor 21. Based on the detection signal of the means, the basic fuel injection amount τ ₁ is calculated by the LJ method and output to the LJ method / DJ method switching means.
The basic fuel injection amount τ by the -J method calculation means and the DJ method
_The D-J method calculating means for calculating _d and outputting it to the L-J method / DJ method switching means, the intake pipe internal pressure value P output from the intake pipe internal pressure detecting means and a predetermined L- determined experimentally. J
Judgment of the method / DJ method switching pressure value P ₀ ,
Intake pipe internal pressure determination means for outputting the determination signal to the LJ method / DJ method switching means, the switching determination means and the acceleration / deceleration correction value correction means, the intake air amount detection means such as the air flow meter 12, and / or the throttle valve. Acceleration / deceleration determination means for determining the acceleration / deceleration state based on the output signal of the opening degree detection means, and a table which is experimentally determined beforehand and stored according to the degree of acceleration / deceleration based on the output signals of the acceleration / deceleration determination means. Based on the above, the acceleration / deceleration correction value is calculated by the LJ method and output to the acceleration / deceleration correction value correction means. Whether or not this is different from this time, in other words, the intake pipe internal pressure detection value P detected by the intake pipe internal pressure detection means.
And the magnitude relationship between the intake pipe pressure detection value P ₀ for switching between the L-J method and the DJ method is opposite to that at the time of the previous measurement, that is, the current detection value P _{n + 1} is the previous value. Detection value P _n and (P _{n + 1} −P _o ) × (P _n −P ₀ ) <0
It is determined whether or not there is a relationship of
Method / DJ method switching means, acceleration / deceleration correction correcting means, switching determination means for outputting to the fuel injection amount correcting means, and LJ method computing means when the switching determination signal input from the switching determination means is YES. and D-J mode both output tau _l and tau _d operation means, and outputs the fuel injection quantity correcting means, on the other hand, in the case of NO in accordance with the determination signal of the intake pipe pressure determining means, L-J-method calculating Means, or one of the outputs τ _l and τ _d of the DJ method computing means is selected as the basic fuel injection amount and is output to the fuel injection amount correcting means.
When the switching determination signal input from the J method / DJ method switching means and the switching determination means is YES, the acceleration / deceleration correction value input from the LJ method acceleration / deceleration correction value calculation means and the experimental value have been experimentally beforehand. The acceleration / deceleration correction value input from the L-J method acceleration / deceleration correction value calculation means is corrected based on a table determined and stored and necessary for calculating the fuel injection amount by the DJ method. The acceleration / deceleration correction value for the DJ system is output to the fuel injection amount correction means. On the other hand, if NO, the fuel injection amount should be corrected by the DJ system according to the intake pipe pressure value P. When the necessary correction is added to the acceleration / deceleration correction value input from the LJ method acceleration / deceleration correction value calculation means to correct the fuel injection amount by the LJ method,
If the switching determination signal input from the acceleration / deceleration correction value correction means that outputs the acceleration / deceleration correction value to the fuel injection amount correction means without correction and the switching determination means is YES, the fuel injection amount is According to the calculation method of the fuel injection amount used for the above, the basic fuel injection amount selected by the LJ method / DJ method switching unit is calculated from the value of the fuel injection amount calculated at this time after a predetermined time. The calculation processing is performed so that the value is gradually switched to the value corrected by the acceleration / deceleration correction value calculated this time. On the other hand, in the case of NO, the basic fuel injection selected by the LJ method / DJ method switching means. The amount is simply corrected by the acceleration / deceleration correction value calculated this time, the fuel injection amount is calculated, and the fuel injection amount correction means for outputting to the fuel injection control means and the output signal of the fuel injection amount correction means are used. Of the fuel injection valve 14 And a fuel injection control means for controlling the valve time.

FIG. 3 is a flowchart showing a method of fuel injection amount control in the fuel injection amount control device 20 shown in FIG.

In the flowchart of FIG. 3, first, the intake air amount data detected by the intake air amount detecting means such as the air flow meter 12, the engine speed data detected by the engine speed detecting means such as the crank angle sensor 22, and the intake pipe The intake pipe internal pressure data detected by the intake pipe internal pressure detecting means such as the pressure sensor 21 is input.

Next, based on these input data, the basic fuel injection amount τ _{l is} calculated by the LJ method calculation means based on the LJ method.
Is calculated, and the basic fuel injection amount τ _d is calculated by the DJ system computing means based on the DJ system. Further, from the intake air flow rate change rate calculated based on the output signal of the intake air flow rate detection means and / or the throttle valve opening change rate calculated based on the output signal of the throttle valve opening degree detection means, acceleration / deceleration determination means accelerates. It is determined whether the state is a deceleration state, or neither. As a result, when the acceleration / deceleration state is determined, the LJ method acceleration / deceleration correction value calculation means calculates the acceleration / deceleration correction value of the basic fuel injection amount based on the LJ method and corrects the acceleration / deceleration correction value. Is output to the means. When the acceleration / deceleration state is not set, this correction value is set to zero. On the other hand, the intake pipe internal pressure data P detected by the intake pipe internal pressure detection means is compared with the predetermined intake pipe internal pressure P ₀ by the intake pipe internal pressure determination means, and the determination signal is the switching determination means, the LJ method / D.
It is output to the -J method switching means and the acceleration / deceleration correction value correction means.

The switching determination means compares the previous determination means input from the intake pipe pressure determination means with the determination signal this time, and whether or not the determination result is reversed, that is, the intake pipe pressure detection means detects this time. Detection value P _{n + 1} and previous detection value P
and _{n is, (P n + 1 -P 0} ) × (P n -P 0) < determines whether zero relationship, a determination signal L-J mode / D-
It is output to the J method switching means, the acceleration / deceleration correction value correcting means, and the fuel injection amount correcting means.

The LJ method / DJ method switching means sets the basic fuel injection amount τ _l based on the LJ method and the basic fuel injection quantity τ _d based on the DJ method when the output signal of the switching determination means is YES. Both are output to the fuel injection amount correction means, while NO
When, the input signal from the intake pipe internal pressure determination means is P <P ₀ according to the intake pipe internal pressure value,
The output value τ _l of the LJ method computing means is selected as the basic fuel injection amount, and when P ≧ P ₀ , the output value τ _d of the DJ method computing means is selected as the basic fuel injection amount, and the fuel Output to the injection amount correction means.

Further, the acceleration / deceleration correction value correcting means, when the output signal of the switching determination means is YES, the acceleration / deceleration correction value output from the LJ system acceleration / deceleration correction value calculating means and D-
The correction values for the DJ method, which have been corrected to correct the fuel injection by the J method, are both output to the fuel injection amount correction means. On the other hand, when NO, the intake pipe internal pressure follows the intake pipe internal pressure value. When the input signal from the determination means is P <P ₀ , the acceleration / deceleration correction value output from the LJ method acceleration / deceleration correction value calculation means is used as the correction value as it is, and when P ≧ P ₀ , D− The correction value for the DJ method obtained by adding the correction necessary for the J method to the acceleration / deceleration correction value is output as the correction value to the fuel injection amount correction means.

Further, the fuel injection amount correction means, which has received the above signals from the LJ method / DJ method switching means, the acceleration / deceleration correction value correction means and the switching determination means, receives the determination signal from the switching determination means. When NO, that is, (P _{n + 1} −P
₀ ) × (P _n −P ₀ ) ≧ 0, the LJ method / DJ
The basic fuel injection amount input from the system switching means is corrected by the acceleration / deceleration correction value input from the acceleration / deceleration correction value correction means to calculate the fuel injection amount, and the fuel injection amount control signal is output to the fuel injection control means. To do. On the other hand, when the determination signal from the switching determination means is YES, that is, (P _{n + 1} −P ₀ ).
When x (P _n −P ₀ ) <0, the LJ method / D− is set after a predetermined time from the value of the fuel injection amount calculated at this time by the previously used calculation method of the fuel injection amount. The fuel injection amount is calculated so that the basic fuel injection amount input this time from the J system switching means is gradually changed to the value corrected by the acceleration / deceleration correction value input this time from the acceleration / deceleration correction value correction means, and the time is calculated. A control signal for gradually increasing or gradually decreasing the fuel injection amount is output to the fuel injection control means with the lapse of time. In one specific example of the time control of the fuel injection amount, for example, when switching the calculation method of the fuel injection amount from the LJ system to the DJ system, a switching calculation I is performed in FIG. , The control value τ of the fuel injection amount at each time point is the acceleration / deceleration correction value by the LJ method, α ₁ , D
The acceleration / deceleration correction value according to the -J method is set as α _d , and control is performed according to the following equation.

[tau] = {(1-k) ([tau] _l + [alpha] _l ) + k ([tau] _d + [alpha] _d )} where k is a switching coefficient that is a function of time, and becomes 1 after a predetermined time t elapses from zero, for example, , Those that change linearly are selected. Also, the above τ _l , τ _d , α
_{Since l} and α _d are also functions of time, in this example, the fuel injection amount after the elapse of a predetermined time is the basic fuel injection amount calculated at the time when the LJ method and the DJ method are switched. The fuel injection amount value obtained from the acceleration / deceleration correction value is not controlled, and the fuel injection amount after the lapse of Δt from the start of the switching calculation is L calculated after the lapse of Δt.
Calculated according to the above formula based on the basic fuel injection amount and acceleration / deceleration correction value by the -J method and DJ method, and after time t-Δt (after time t from the start of switching calculation)
In other words, the target fuel injection amount is also set to a different value over time. Further, before the predetermined time has elapsed after the switching calculation was started, the intake pipe internal pressure value P again becomes
When (P _{n + 1} −P ₀ ) × (P _n −P ₀ ) <0 is satisfied, in this example, when the DJ system is switched to the LJ system, τ _l and τ _d ,
The switching operation II in which α ₁ and α _d are respectively replaced is executed. First, from the DJ system to the L-
In the case of switching to the J system and then switching from the LJ system to the DJ system, an operation opposite to the above, that is, the switching operation II is first executed, and subsequently, the switching operation I Will be executed.

Upon receiving the fuel injection amount control signal from the fuel injection amount correction unit, the fuel injection control unit drives the fuel injection valve 14 according to the signal and controls the valve opening time.

It is needless to say that the present invention is not limited to the above embodiments and various modifications can be made within the scope of the invention described in the claims.

Further, in the embodiment shown in FIGS. 2 and 3, the acceleration / deceleration correction value is calculated by the LJ method, and the acceleration / deceleration correction value of the DJ method is used for the DJ method. However, on the contrary, the acceleration / deceleration correction value is calculated by the DJ method, and the acceleration / deceleration correction value of the LJ method is used for the LJ method. It is obvious that the calculation may be performed by adding necessary corrections, and the acceleration / deceleration correction value can be calculated based on the LJ method and the DJ method. Further, in the above-described embodiment, the switching calculation is performed at that time using the value of the fuel injection amount calculated by the previously used fuel injection amount calculation method as the reference value, but the previous fuel injection amount ( A value obtained by removing the correction amount other than acceleration / deceleration correction from the actual fuel injection amount,
That is, it is also possible to store a value obtained by correcting the previously calculated basic fuel injection amount with the previously calculated acceleration / deceleration correction value) and perform the switching calculation using this value as a reference value.

EFFECTS OF THE INVENTION According to the present invention, even when it is necessary to switch the fuel injection amount calculation method between the LJ method and the DJ method in a transient state where the operating state of the engine is changing. ,
It is possible to provide a control device for an electronic injection type engine capable of controlling the fuel injection amount so as to give an optimum air-fuel ratio.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention. FIG. 2 is a block diagram of the fuel injection amount control device according to the embodiment of the present invention, and FIG. 3 is a flowchart showing the control method thereof. 1 ... Engine, 2 ... Cylinder bore, 3 ... Piston, 4 ... Combustion chamber, 5 ... Intake port, 6 ... Exhaust port, 9 ... Intake passage, 12 ... Air flow meter, 13 ... Throttle valve , 14 ... Fuel injection valve, 20 ... Fuel injection amount control device, 21 ... Intake pipe pressure sensor, 22 ... Crank angle sensor

Claims (1)

[Claims] 1. An air flow meter for detecting an intake air amount provided in an intake system, a load detecting means for outputting a signal corresponding to an intake negative pressure downstream of a throttle valve, and an engine speed detection for detecting an engine speed. Means, an LJ method fuel injection amount calculation means for calculating a basic fuel injection amount by the LJ method based on the output of the air flow meter, and an output of the load detection means and the engine speed detection means. DJ which calculates basic fuel injection quantity by DJ method
In the system fuel injection amount calculation means and in the operating region where the intake air amount or engine load exceeds a predetermined value, the basic fuel injection amount calculated by the DJ fuel injection amount calculation means is selected, and the intake air amount or engine is selected. In the operating region where the load is equal to or less than a predetermined value, the basic fuel injection amount selecting means for selecting the basic fuel injection amount calculated by the LJ method fuel injection amount calculating means, and the operating state for the basic fuel injection quantity selecting means It is determined whether or not there is a change between the operating state in which the injection amount should be calculated and the operating state in which the basic fuel injection amount should be calculated by the DJ method. When it is determined that there is a change, a switching signal is output. A switching determination means, a transient detection means for detecting a transient time of the engine, and a basic fuel injection amount calculated by the LJ fuel injection amount calculation means based on a transient detection signal of the transient detection means. And a transient fuel injection amount correction value calculation means for calculating a transient correction value for correcting the basic fuel injection amount calculated by the DJ method fuel injection amount calculation means. In the method, the basic fuel injection amount selection means outputs a switching signal from the switching determination means based on the output signals from the transient fuel injection amount correction value calculation means, the basic fuel injection amount selection means and the switching determination means. When not input, according to the operating state at that time, the basic fuel injection amount input from the basic fuel injection amount selection means is corrected by the transient correction value input from the transient fuel injection amount correction value calculation means, On the other hand, when the switching signal is input from the switching determination means, the basic fuel injection calculated according to the method used before the switching signal is input. From the value of the amount, the fuel injection amount corrected by the transient correction value input from the transient fuel injection amount correction value calculation unit, the basic fuel injection amount input from the basic fuel injection amount selection unit after a predetermined time. A fuel injection amount correction means for executing a switching calculation of the basic fuel injection amount and outputting a fuel injection control signal to a fuel injection control means for controlling the fuel injection valve is provided so that the value gradually changes to the value. When the switching signal is input from the switching means before the completion of the switching calculation, the injection amount correction means, from the value of the basic fuel injection amount calculated according to the method used before the input of the switching signal, After the lapse of the predetermined time, the basic fuel injection amount input from the basic fuel injection amount selection means is corrected by the transient correction value input from the transient fuel injection amount correction value calculation means A control method for a fuel control device for an electronic fuel injection engine, which is characterized in that the switching calculation of the basic fuel injection amount is executed again so that the value gradually changes.