JP2006249993A - Fuel injection control device and fuel injection control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further increase fuel economy by well maintaining exhaust emission while securing the startability of an engine in a fuel injection control. <P>SOLUTION: In a fuel injection control device, a fuel injection amount in each cylinder by an independent injection is adjusted in consideration of the amount of a fuel remained by a previous simultaneous injection. Accordingly, the injected amount of fuel by the independent injection can be set to an appropriate value without excess and shortage while securing the startability of the engine by the simultaneous injection, and even immediately after a switching from the simultaneous injection to the independent injection, a fuel injection control near a theoretical air-fuel ratio can be achieved. As a result, the exhaust emission can be well maintained and the fuel economy can be increased. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection control device that has a simultaneous injection method and an independent injection method and controls a fuel injection amount supplied to an engine.

  In general, when a vehicle engine is started, a cylinder discrimination process for discriminating to which cylinder fuel injection is performed is executed. When this cylinder discrimination is performed, it is necessary to rotate the crankshaft. For this reason, the startability is ensured by performing simultaneous injection (asynchronous injection) on all cylinders immediately after the start of the engine, and when the engine speed rises to some extent, it is synchronized with the intake stroke for each cylinder. It switched to the independent injection (synchronous injection) which performs fuel injection separately (for example, refer to patent documents 1).

That is, at the time of engine start, regardless of whether each cylinder is in the intake, compression, combustion, or exhaust stroke, simultaneous injection is performed a predetermined number of times in the intake manifold located upstream of the combustion chamber of each cylinder, The required fuel injection amount is secured to improve engine startability. Then, when the cylinder discrimination process is completed and the engine speed is stabilized, the process shifts to independent injection in which fuel is individually injected in accordance with the intake stroke of each cylinder, and fuel injection control close to the stoichiometric air-fuel ratio is performed. It was.
JP 2003-155945 A (paragraph numbers [0003], [0004])

  However, in such fuel injection control, the cylinders that enter the intake stroke simultaneously with the start of simultaneous injection and the other cylinders differ in the amount of fuel sucked into the cylinder during each intake stroke at the start. That is, depending on the number of simultaneous injections, there is a difference in the effective injection amount when switching from simultaneous injection to independent injection between the cylinders. For this reason, it is difficult to realize the stoichiometric air-fuel ratio in each cylinder, the intended fuel injection amount cannot be obtained in a certain cylinder, and the mixture gas may become lean misfire and incomplete combustion may occur. Further, in the other cylinders, the air-fuel mixture is richly burned by excessive fuel, the catalytic effect is reduced, and emission of harmful substances such as HC and CO is increased, which may deteriorate exhaust emission. Especially in the latter case, there is a problem that excessive fuel is sucked in, leading to deterioration of fuel consumption.

  Note that the above-described simultaneous injection is performed when the engine rotation state is unstable, such as when the engine speed is low even when the cylinder discrimination process is completed when the engine is started, or when the engine speed decreases when the engine is stopped. In this case, the same problem occurs.

  The present invention has been made in view of the above points, and a fuel injection control device and a fuel injection control method capable of maintaining good exhaust emission and improving fuel efficiency while ensuring startability of the engine. The purpose is to provide.

In the present invention, in order to solve the above-described problem, in a fuel injection control device that performs switching between simultaneous injection for simultaneously injecting fuel into all cylinders of an engine and independent injection for sequentially injecting fuel for each cylinder according to a predetermined condition. There is provided a fuel injection control device that adjusts the independent injection amount in each cylinder based on the simultaneous injection amount injected in each cylinder before the independent injection.

  In such a fuel injection control device, the fuel injection amount by independent injection performed in each cylinder at the time of switching from simultaneous injection to independent injection is based on the fuel injection amount by simultaneous injection previously performed in each cylinder. Adjusted.

  According to the fuel injection control device of the present invention, the fuel injection amount by independent injection is adjusted based on the fuel injection amount by simultaneous injection. For this reason, the fuel injection amount by the independent injection can be set to an appropriate value for bringing it close to the theoretical air-fuel ratio while ensuring the startability of the engine by the simultaneous injection. As a result, the exhaust emission can be maintained well and the fuel consumption can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, the fuel injection control device of the present invention is applied to a vehicle equipped with a four-cylinder four-cycle engine. FIG. 1 is a schematic configuration diagram showing the configuration around the engine of the present embodiment.

  An intake pipe 2 is connected to the upstream side of the intake and exhaust system of the engine 1 of the vehicle, and an exhaust pipe 3 is connected to the downstream side. An air cleaner 4 is provided at the upstream end of the intake pipe 2, and an intake manifold 5 that divides the intake passage for each cylinder is provided at the downstream end. The air introduced into the intake pipe 2 via the air cleaner 4 is sucked into each cylinder through the intake manifold 5.

  A surge tank 6 is provided at an intermediate portion of the intake pipe 2, and a bypass passage 8 is formed so as to bypass the throttle valve 7 disposed slightly upstream. An idle speed control valve (hereinafter referred to as “ISCV”) 9 for adjusting the flow rate of air to be bypassed is disposed in the bypass passage 8. During idling, the engine speed is adjusted by controlling the valve opening of the ISCV 9 to adjust the intake air amount.

  In the intake manifold 5, injectors 10 are arranged in intake ports provided for each cylinder. The injector 10 is supplied with fuel that has been pumped from a fuel tank (not shown) and pressure-regulated, and is opened by energization control to inject fuel into the intake port. The fuel injected at this time is mixed with the intake air introduced from the upstream side to become an air-fuel mixture, and is supplied to the combustion chamber 12 via the intake valve 11 to each cylinder.

  A spark plug 13 is disposed in the combustion chamber 12 of each cylinder. The spark plug 13 is applied with a high voltage generated by an ignition coil integrated igniter 14 to generate a spark for ignition. By this ignition, the air-fuel mixture in the combustion chamber 12 is combusted, and a rotational force is applied to the crankshaft 16 through the piston 15.

  An exhaust manifold 17 is provided at the upstream end portion of the exhaust pipe 3 so as to join exhaust passages for the respective cylinders and send the exhaust passage toward a muffler (not shown) at the downstream end. The gas exhausted from the combustion chamber 12 is led to the exhaust pipe 3 through the exhaust manifold 17, purified by the catalytic converter 18, and sent to the muffler.

An air flow meter 19 integrated with an intake air temperature sensor is provided at the most upstream portion of the intake pipe 2 so that the intake air amount and the intake air temperature can be detected. Further, a throttle opening sensor 20 for detecting the opening degree of the throttle valve 7 is provided near the throttle valve 7 of the intake pipe 2.
Is provided.

  Further, the engine 1 is provided with a water temperature sensor 21 for detecting the temperature of engine cooling water and a knock sensor 22 for detecting knocking of the engine 1. Further, the igniter 14 includes a cam position sensor for performing cylinder discrimination by detecting the top dead center (referred to as “compression TDC”) of the compression stroke from the rotation of a cam shaft provided corresponding to each cylinder. 23 is arranged. Further, in the vicinity of the crankshaft 16, a crank angle sensor 24 that generates a crank angle signal at every predetermined crank angle accompanying the rotation of the crankshaft 16 is disposed in order to calculate the engine speed.

Further, the exhaust pipe 3 is provided with an oxygen sensor 25, and the oxygen sensor 25 can detect the oxygen concentration in the exhaust gas of the engine 1.
The fuel injection control of the engine 1 is executed by an electronic control unit (hereinafter referred to as “ECU”) 30 mainly composed of a microcomputer. In the present embodiment, the ECU 30 constitutes a fuel injection control device. FIG. 2 is a block diagram showing the ECU 30 and its input / output.

  The ECU 30 includes a CPU (Central Processing Unit) that executes various arithmetic processes, a ROM (Read Only Memory) that stores various control arithmetic programs and data, and a RAM (Random Access) that stores numerical values and flags of arithmetic processes in a predetermined area. Memory), EEPROM (Electronically Erasable and Programmable Read Only Memory) which is a non-volatile storage device for storing the result of arithmetic processing, and A / D (Analog / Digital) converter for converting an input analog signal into a digital signal , An input / output interface for inputting / outputting various digital signals, a bus line to which these devices are connected, and the like.

  The ECU 30 takes in output signals from various sensors that detect the state of the engine 1 and outputs drive signals to various actuators provided in the engine 1. In other words, the ECU 30 includes the air flow meter 19 (including the intake air temperature sensor), the throttle opening sensor 20, the water temperature sensor 21, the knock sensor 22, the cam position sensor 23, the crank angle sensor 24, and the oxygen sensor 25. Also, an intake pressure sensor 41 for detecting the pressure in the intake pipe 2, an accelerator opening sensor 42 for detecting the amount of depression of the accelerator pedal, a vehicle speed sensor 43 for detecting the vehicle speed from the rotation of the vehicle drive shaft, an ignition switch 44, a starter switch Sensors and switches such as 45 are connected, and fuel is pumped from the injectors 10 (INJ1 to INJ4), igniters 14 (IGT1 to IGT4) and fuel tanks of the cylinders (# 1 to # 4) and supplied to the injectors 10 To open and close the fuel pump 46 and the throttle valve 7 Liters drive motor 47, various actuators such as the starter motor 48 to the engine 1 is cranking is connected. The ECU 30 performs a predetermined control process according to a control program stored in the ROM.

  Next, the fuel injection control method of this embodiment will be described. Here, first, the outline of the simultaneous injection and the independent injection executed by the fuel injection control of the present embodiment will be individually described, and then the specific fuel injection control of the present embodiment performed by switching between them. Will be described.

FIG. 3 is a timing chart showing an example of simultaneous injection. In the figure, the horizontal axis represents time, and the vertical axis represents fuel injection timing in each cylinder.
That is, a counter that counts four cycles of intake, compression, combustion, and exhaust and a counter that counts the compression TDC of each cylinder are set in a predetermined area of the RAM of the ECU 30. And injection control is performed based on the count value of both counters.

  In this simultaneous injection, when any one of the cylinders reaches compression TDC, that is, every cylinder performs simultaneous injection. The fuel injection amount in each simultaneous injection is set to ¼ of the fuel injection amount in each cylinder during normal independent injection, that is, during normal traveling where the engine speed is stable. For this reason, in the intake stroke of each cylinder, the fuel amount at the time of normal independent injection is theoretically sucked.

FIG. 4 is a timing chart showing an example of independent injection. In the figure, the horizontal axis represents time, and the vertical axis represents fuel injection timing in each cylinder.
In this independent injection, independent injection is executed every time the intake TDC is reached in each cylinder (that is, every 720 ° CA). At this time, some of the intake ports of each cylinder in the intake manifold 5 have fuel remaining due to simultaneous injection in the previous stroke. For this reason, at least at the first independent injection in each cylinder, the remaining fuel amount is subtracted from the fuel amount injected by normal independent injection (independent injection performed when the engine speed is stable). A correction process (detailed later) for injecting the fuel amount is executed. When the fuel remaining in the intake port runs out, normal independent injection is executed. For this reason, in the intake stroke of each cylinder, theoretically, fuel equal to the fuel amount during normal independent injection is sucked.

Next, specific fuel injection control of the present embodiment will be described.
FIG. 5 is a timing chart showing a method of fuel injection control including switching timing between simultaneous injection and independent injection according to the present embodiment. Note that the example in the figure represents the fuel injection control executed when the vehicle engine is started. In the figure, the horizontal axis represents time, and the vertical axis represents the engine speed, the state of fuel injection control, and the fuel injection timing in each cylinder from the top.

  In this fuel injection control, the above-described simultaneous injection is executed in parallel with the cylinder discrimination process performed during idling immediately after the engine 1 is started. When the engine speed NE becomes equal to or higher than the set speed N1 (for example, 300 rpm), the simultaneous injection is terminated and the process proceeds to independent injection. At this time, even if the cylinder discrimination process is finished, if the engine speed decreases due to the instability of the engine at the start and becomes lower than the set speed N1 again, the simultaneous injection is started again. At this time, every time the simultaneous injection is switched to the independent injection, a correction process described later is executed. When such processing is repeated and the engine speed is stabilized at the set speed N1 or more, normal independent injection is continuously executed.

  FIG. 6 is a timing chart showing a specific method of fuel injection control including a correction process that is executed when the engine is started. In the figure, the horizontal axis represents the passage of time, and the vertical axis represents the fuel injection timing and fuel injection amount by the injector 10 (INJ1 to INJ4) of each cylinder (# 1 to # 4) from the upper stage, and the igniter 14 (IGT1 to IGT4). ) And the stroke of each cylinder (# 1 to # 4). In addition, what was shown by the star in the fuel injection timing represents simultaneous injection. Here, each simultaneous injection amount is set to 1/4 of the fuel injection amount by normal independent injection. In addition, what is indicated by a number (fraction) at the fuel injection timing represents the fuel injection amount in the independent injection. The numbers shown here represent the ratio to the fuel injection amount by normal independent injection. In the ignition timing, the black circle represents the ignition operation.

  In the example shown in the figure, simultaneous injection is executed in the first cycle of four cycles immediately after the engine is started, and thereafter, it is shifted to independent injection. In each cylinder, the fuel injected into the intake port of the intake manifold 5 is sucked in the intake stroke.

Specifically, in the first cylinder # 1, since intake is performed simultaneously with the start of simultaneous injection, the subsequent three strokes of compression, combustion, and exhaust are performed. / 4 fuel is stored. For this reason, at the start of the independent injection, fuel of ¼ of the fuel injection amount by the normal independent injection is injected by the correction process, sucked into the combustion chamber 12 in the subsequent intake stroke, and ignited in the compression stroke. At this time, since there is no fuel remaining in the intake port, fuel injection is executed with a normal fuel injection amount (that is, a fuel amount of 4/4) for the subsequent independent injection.

  Further, in the second cylinder # 2, since the start time of the simultaneous injection corresponds to the exhaust stroke, 2/4 of the fuel injection amount by the normal independent injection is accumulated in the intake port when the independent injection is started. For this reason, at the start of independent injection, fuel of 2/4 of the fuel injection amount by normal independent injection is injected by the correction process, sucked into the combustion chamber 12 in the subsequent intake stroke, and ignited in the compression stroke. At this time, since there is no fuel remaining in the intake port, fuel injection is executed with a normal fuel injection amount (that is, a fuel amount of 4/4) for the subsequent independent injection.

  Further, in the third cylinder # 3, since the start time of the simultaneous injection corresponds to the combustion stroke, at the start of the independent injection, ¼ of the fuel injection amount by the normal independent injection is accumulated in the intake port. For this reason, at the start of independent injection, fuel of 3/4 of the fuel injection amount by normal independent injection is injected by the correction process, sucked into the combustion chamber 12 in the subsequent intake stroke, and ignited in the compression stroke. At this time, since there is no fuel remaining in the intake port, fuel injection is executed with a normal fuel injection amount (that is, a fuel amount of 4/4) for the subsequent independent injection.

  Further, in the fourth cylinder # 4, since the start time of the simultaneous injection corresponds to the compression stroke, the fuel amount equal to the fuel injection amount by the normal independent injection is sucked in the intake stroke which is the final stroke of the simultaneous injection. For this reason, at the start of the independent injection, fuel (4/4) of the fuel injection amount by the normal independent injection is injected by the correction process, sucked into the combustion chamber 12 in the subsequent intake stroke, and ignited in the compression stroke. . At this time, since the fuel remaining in the intake port has already disappeared, the fuel injection is executed with the normal fuel injection amount (that is, the fuel amount of 4/4) in the subsequent independent injection.

  Next, the process flow of the above-described fuel injection control will be described. FIG. 7 is a flowchart showing the flow of fuel injection control processing executed by the ECU. Hereinafter, the flow of this process will be described using step numbers (hereinafter referred to as “S”).

  Here, based on a preset program, simultaneous injection is performed in an unstable state where the engine speed is lower than the set speed, such as when the engine is started. The following processing is repeatedly executed from when the engine 1 starts to stop.

  First, based on the engine speed, it is determined whether or not the simultaneous injection execution condition is satisfied (S110). At this time, if it is determined that simultaneous injection has been performed (S110: YES), a simultaneous injection number counter preset in a predetermined area of the RAM is incremented by 1 (S120), and the above-described simultaneous injection processing is executed once (S130). The processes of S110 to S130 are repeated until the simultaneous injection process is completed and the execution condition is not satisfied.

  On the other hand, if it is determined in S110 that the simultaneous injection execution condition is not satisfied (S110: NO), the simultaneous injection counter is cleared (S140).

Subsequently, it is determined whether or not it is a time of switching from simultaneous injection to independent injection. At this time, if it is determined that simultaneous injection has been performed at the previous time and it is the time of switching (S150: YES), the above-described independent injection correction processing is executed (S160). Details of this processing will be described later.

On the other hand, if it is determined in S150 that it is not at the time of switching, such as when independent injection has already been executed (S150: NO), the normal independent injection described above is executed (S170).
FIG. 8 is a flowchart showing the flow of the independent injection correction process executed by the ECU in S160.

  As shown in the drawing, in the above-described independent injection correction process, first, a total fuel injection amount (referred to as “total simultaneous injection amount”) by simultaneous injection executed before that is calculated for each cylinder (S210). This total amount of simultaneous injection means the amount of fuel that is simultaneously injected before the start of independent injection and remains in each intake port without being inhaled. Therefore, in a cylinder that has an intake stroke during simultaneous injection, the amount of fuel injected in the stroke after the intake stroke is calculated.

  Subsequently, a fuel injection amount by normal independent injection (also referred to as “independent injection amount”) is calculated (S220). As described above, the normal independent injection amount is an independent injection amount that is executed when the engine speed is stabilized at a set value or more, but may vary depending on the control state of the vehicle.

Then, the independent injection amount is corrected by the following equation (1), and this is calculated as the corrected independent injection amount (S230).
Independent injection amount after correction = (Normal independent injection amount-Total simultaneous injection amount) (1)
For example, in the example shown in FIG. 6, assuming that the normal independent injection amount is 1 for the first cylinder # 1, the total simultaneous injection amount before the first independent injection is 3/4. The injection amount is ¼.

  Subsequently, in order to determine whether or not to apply the corrected independent injection amount, it is determined whether or not the corrected independent injection amount is smaller than the normal independent injection amount (S240). At this time, if it is determined that the corrected independent injection amount is smaller than the normal independent injection amount (S240: YES), independent injection based on the corrected independent injection amount is executed (S250). This is because when the corrected independent injection amount is smaller than the normal independent injection amount, the necessary fuel injection amount is smaller than the normal independent injection amount. This is because the fuel is excessive.

  On the other hand, when it is determined in S240 that the corrected independent injection amount is greater than or equal to the normal independent injection amount (S240: NO), normal independent injection is executed (S260). Thereby, the correction process is executed until the corrected independent injection amount matches the normal independent injection amount.

  As described above, according to the fuel injection control device of the present embodiment, the fuel injection amount in each cylinder by independent injection is adjusted in consideration of the fuel amount remaining by the previous simultaneous injection. For this reason, while ensuring the startability of the engine 1 by simultaneous injection, the fuel injection amount by independent injection is set to an appropriate value without excess and shortage, and fuel injection close to the stoichiometric air-fuel ratio immediately after switching from simultaneous injection to independent injection Control can be realized. As a result, the exhaust emission can be maintained well and the fuel consumption can be improved.

In the above embodiment, the corrected independent injection amount is calculated by the above equation (1). However, various other methods for calculating the corrected independent injection amount can be considered.
For example, assuming that the fuel injection amount by one simultaneous injection (also referred to as “simultaneous injection amount”) is equal, the fuel amount for N simultaneous injections is sucked in one intake stroke. You may make it calculate by Formula (2).

Independent injection amount after correction = (N-number of simultaneous injections) x simultaneous injection amount (2)
Here, the number of simultaneous injections means the number of times that the combustion chamber 12 was not inhaled among the number of simultaneous injections before the independent injection. In the present embodiment, N corresponds to the number of cylinders. Thereby, even if the number of cylinders changes, the corrected independent injection amount can be easily calculated.

The correction process is performed until the corrected independent injection amount matches the normal independent injection amount. However, the number of corrections can be set by the following equation (3), for example.
Number of corrections = (number of cylinders -1) (3)
This number of corrections may be executed at the top dead center timing of each stroke. Thereby, when the number of cylinders is determined, the number of corrections can be easily set due to the program configuration.

  Further, the present embodiment has been described on the assumption that the fuel injected into the intake port of the intake manifold 5 is all sucked in the next intake stroke. However, for example, when the coolant temperature of the engine cooling water is low, a part of the fuel injected into the intake port by the simultaneous injection may adhere to the side wall and remain without being sucked even in the intake stroke. There is. In that case, sufficient fuel is not supplied to the combustion chamber 12. Therefore, in such a case, the independent injection time at the time of correction may be extended, or the number of corrections may be increased so as to be close to the theoretical air-fuel ratio.

  FIG. 9 is an explanatory diagram illustrating an example of a correspondence relationship between the water temperature and the number of times the correction process is extended. As described above, the number of times of extension may be increased as the water temperature is lower, and may be decreased as the water temperature is higher. Thereby, it is possible to introduce a sufficient air-fuel mixture into the combustion chamber 12, and it is possible to prevent the fuel from becoming excessive. However, the number of times of extension is not limited to the one shown in the figure, and can be determined according to the matching condition with each control.

  Further, in the present embodiment, the simultaneous injection amount per time is set to an amount obtained by dividing the normal independent injection amount by the number of cycles (4 cycles), but a fuel injection amount different from that may be set. On the contrary, the normal independent injection amount may fluctuate in the control process, and may not always be set as such.

  In such a case, the corrected independent injection amount calculated as described above may be 0 or less. If fuel injection is performed at that time, there is a possibility of over-richness, but in consideration of the case where a part of fuel adheres to the side wall of the intake port due to simultaneous injection as described above, fuel injection is performed. You may make it do. Thereby, lean misfire etc. can be prevented.

  In the present embodiment, an example is shown in which simultaneous injection is executed once per cycle. However, the timing of simultaneous injection is not limited to this, for example, simultaneous injection is executed once every two cycles, and simultaneous injection is performed. It is also possible to double the amount.

It is a schematic block diagram showing the structure around the engine of embodiment. It is a block diagram showing ECU and its input-output. It is a timing chart showing the method of simultaneous injection. It is a timing chart showing the method of normal independent injection. It is a timing chart showing the method of fuel injection control including the switching timing of simultaneous injection and independent injection. It is a timing chart showing the specific method of the fuel-injection control including the correction process performed at the time of engine starting. It is a flowchart showing the flow of the process of the fuel injection control which ECU performs. It is a flowchart showing the flow of the independent injection correction process which ECU performs. It is explanatory drawing which shows an example of the correspondence of water temperature and the frequency | count of extension of a correction process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake pipe 3 Exhaust pipe 5 Intake manifold 10 Injector 11 Intake valve 12 Combustion chamber 14 Igniter 16 Crankshaft 17 Exhaust manifold

Claims (8)

In a fuel injection control device that executes simultaneous injection that simultaneously injects fuel into all cylinders of an engine and independent injection that sequentially injects fuel for each cylinder according to a predetermined condition,
A fuel injection control device that adjusts the fuel injection amount by the independent injection in each cylinder based on the fuel injection amount by the simultaneous injection injected by each cylinder before the independent injection.   The amount of fuel injected by the independent injection first after switching from at least the simultaneous injection in each cylinder is the amount of fuel injected into the intake port of each cylinder by the simultaneous injection from the fuel injection amount set to normal independent injection. The fuel injection control device according to claim 1, wherein the fuel injection control device is corrected to an amount obtained by subtracting.   The fuel amount is calculated based on the number of simultaneous injections performed from the compression stroke of each cylinder to the next compression stroke at the time of the simultaneous injection and the fuel injection amount per one simultaneous injection. The fuel injection control device according to claim 2, wherein the fuel injection control device is obtained by calculating a total amount of fuel injected into the fuel.   The correction process of the fuel injection amount by the independent injection performed at the time of switching from the simultaneous injection to the independent injection is a fuel injection amount in which the fuel injection amount by the independent injection after the correction is set to the normal independent injection 3. The fuel injection control device according to claim 2, wherein the fuel injection control device is executed until   The independent injection by the correction can be extended based on the coolant temperature of the engine even after the corrected fuel injection amount by the independent injection set by subtracting the fuel amount is finished. The fuel injection control device according to claim 2, characterized in that:   The fuel injection control device according to claim 2, wherein the independent injection is corrected in consideration of the amount of fuel adhering to the wall surface. In a fuel injection control device that executes simultaneous injection for injecting fuel into all cylinders of an engine at the same time and independent injection for injecting fuel in accordance with the intake timing for each cylinder according to a predetermined condition,
Switching means for switching between the simultaneous injection and the independent injection based on the engine speed;
An injection amount correcting unit that corrects the fuel injection amount by the independent injection based on the fuel amount remaining without being sucked into each cylinder before the switching by the switching unit;
A fuel injection control device comprising: In a fuel injection control method that executes simultaneous injection for injecting fuel into all cylinders of an engine at the same time and independent injection for sequentially injecting fuel for each cylinder according to a predetermined condition,
A fuel injection control method, wherein the fuel injection amount by the independent injection in each cylinder is adjusted based on the fuel injection amount by the simultaneous injection injected by each cylinder before the independent injection.

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