JP2001271687A - Fuel injection control device for multi-cylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device for a multi-cylinder internal combustion engine, capable of suppressing deterioration of a combustion state of each cylinder and lowering of torque which accompanies the deterioration and improving idling stability, in a warming-up process. SOLUTION: An ECU 50 calculates equal injection quantity TAU0 of all the cylinders, based on intake air quantity Ga of an engine 11, engine speed NE and a cooling water temperature THW. The ECU 50 determines final fuel injection quantity TAU1 of a #1 cylinder with the lowest cylinder temperature, by increasing and correcting equal injection quantity TAU0 of all the cylinders in the warming-up process of the engine 11. By increasing and correcting final fuel injection quantity TAU1 of the #1 cylinder in this way, the combustion state of the #1 cylinder can be improved and combustion fluctuation between cylinders can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a multi-cylinder internal combustion engine.

[0002]

2. Description of the Related Art In general, in a vehicle-mounted multi-cylinder internal combustion engine, fuel is injected from a fuel injection valve into an intake passage to supply a mixture of air and fuel to each combustion chamber, and the mixture is burned. Driven by In such a multi-cylinder internal combustion engine, during the warm-up process, the volatility of the fuel attached to the inner surface of the intake passage or the like becomes poor, and the amount of fuel supplied to the combustion chamber becomes smaller than an appropriate amount, so that the air-fuel ratio of the internal combustion engine becomes excessive. The engine becomes lean, and idle rotation during the warm-up process of the internal combustion engine becomes unstable. In addition, during the warming-up process of such a multi-cylinder internal combustion engine, it adheres to the inner surface of the intake passage according to the engine load (the amount of air taken into the combustion chamber when one combustion cycle is performed in the internal combustion engine). The volatilization amount of the fuel fluctuates. Therefore, the amount of fuel supplied to the combustion chamber also fluctuates due to the engine load, and the air-fuel ratio of the air-fuel mixture in the combustion chamber deviates from an appropriate value, and the idle rotation during the warm-up process becomes unstable.

In order to suppress the idling of the internal combustion engine from becoming unstable during the warming-up process of the internal combustion engine as described above, for example, as in a fuel injection control device disclosed in Japanese Patent Application Laid-Open No. 9-177580, There has been proposed a technique in which the fuel injection amount is sometimes increased according to the engine load. In the fuel injection control device described in the publication, the correction increase of the fuel injection amount is increased as the engine load increases in the process of warming up the internal combustion engine. The accompanying deviation of the air-fuel ratio from the appropriate value is suppressed.

[0004]

However, in the above-described multi-cylinder internal combustion engine, the cooling water is circulated in the cooling water passages of the cylinder block and the cylinder head.
The heat of each cylinder is absorbed to cool each cylinder. Therefore, in the warm-up process of the multi-cylinder internal combustion engine, the temperature of each cylinder does not rise similarly, the cylinder temperature is lower in the cylinder upstream of the cooling water, and the cylinder temperature is higher in the cylinder downstream of the cooling water. Therefore, there is a difference between the cylinder temperatures. When the cylinder temperature has a difference between the cylinders as described above, the valve clearance of the intake / exhaust valve corresponding to each cylinder has a different value, and the length of the valve overlap period differs for each cylinder. Then, the valve overlap period of the cylinder with the smallest valve clearance becomes the longest, and the internal exhaust gas recirculation (EGR) amount of the cylinder becomes large. In such a cylinder having a large internal EGR amount, the amount of intake air into the cylinder decreases, and the combustion state of the cylinder decreases, causing a decrease in torque and an unstable idling rotational speed. In the warming-up process of the multi-cylinder internal combustion engine, the temperature of the combustion chamber wall surface is low in a cylinder having a low cylinder temperature, so that the combustion state is reduced to cause a decrease in torque, and the idle rotation speed becomes unstable.

The present invention has been made in view of such circumstances, and has as its object to suppress the deterioration of the combustion state of each cylinder and the accompanying decrease in the torque during the warm-up process of the internal combustion engine, and to achieve idle stabilization. It is an object of the present invention to provide a fuel injection control device for a multi-cylinder internal combustion engine that can improve the performance.

[0006]

According to a first aspect of the present invention, an internal combustion engine includes a plurality of cylinders, and a fuel injection amount to each cylinder is calculated based on an operation state of the internal combustion engine. In the fuel injection control device for a multi-cylinder internal combustion engine, the fuel injection timing is calculated in the following manner. In the warm-up process of the internal combustion engine, the fuel injection amount is increased and the fuel injection amount is corrected for the cylinder whose combustion state is reduced based on the temperature of each cylinder. The gist is that a correction means for performing at least one of the timing advance correction is provided.

[0007] In a multi-cylinder internal combustion engine, during the warm-up process, the temperature rise of a plurality of cylinders causes a difference between the cylinders, whereby the combustion state of each cylinder also causes a difference between the cylinders. On the other hand, according to the invention of claim 1, at least one of the correction of the increase in the fuel injection amount and the correction of the advance of the fuel injection timing is performed for the cylinder whose combustion state is reduced based on the temperature of the cylinder in the warm-up process. I have to. As described above, by performing the increase correction of the fuel injection amount to the cylinder, the air-fuel ratio becomes rich, and the combustion state of the cylinder is improved. Further, by performing the advance correction of the fuel injection timing, the vaporization of the fuel spray proceeds and the spray particle diameter becomes small, so that the fuel spray becomes easy to burn and the combustion state of the cylinder is improved. By improving the combustion state of the cylinder in this way, fluctuations in combustion between cylinders can be suppressed, and idle stability during the warm-up process of the multi-cylinder internal combustion engine can be improved.

According to a second aspect of the present invention, in the fuel injection control apparatus for a multi-cylinder internal combustion engine according to the first aspect, the correcting means determines the fuel injection amount for at least the cylinder having the lowest cylinder temperature in a warm-up process. The gist is that at least one of the increase correction and the advance correction of the fuel injection timing is performed.

In the process of warming up a multi-cylinder internal combustion engine, the temperature of the combustion chamber wall surface of the cylinder having the lowest cylinder temperature is low, and the combustion state is lower than the combustion state of the other cylinders. On the other hand, according to the invention of claim 2, at least one of the increase correction of the fuel injection amount and the advance correction of the fuel injection timing is performed for at least the cylinder having the lowest cylinder temperature in the warm-up process. Therefore, the combustion state of the cylinder can be improved to suppress the fluctuation of combustion between the cylinders, and the idle stability in the warm-up process of the multi-cylinder internal combustion engine can be improved.

[0010] The invention described in claim 3 is the first and second inventions.
In the fuel injection control device for a multi-cylinder internal combustion engine according to any one of the above, the correction means may perform the increase correction of the fuel injection amount and the correction of the fuel injection timing for the cylinder in which at least the valve clearance of the exhaust intake valve is smallest during the warm-up process. The gist is that at least one of the lead angle correction is performed.

[0011] During the warming-up process of the multi-cylinder internal combustion engine, the temperature rise of the plurality of cylinders causes a difference between the cylinders, and the valve clearance of the exhaust / intake valve of each cylinder also causes a difference between the cylinders. In the cylinder with the smallest valve clearance, the valve overlap period becomes longer and the amount of internal exhaust gas recirculation increases, so that the combustion state is lower than the combustion state of the other cylinders. On the other hand, according to the third aspect of the invention, at least one of the increase correction of the fuel injection amount and the advance correction of the fuel injection timing is performed for at least the cylinder in which the valve clearance of the exhaust intake valve is smallest during the warm-up process. I have to. Therefore, the combustion state of the cylinder can be improved to suppress the fluctuation of combustion between the cylinders, and the idle stability in the warm-up process of the multi-cylinder internal combustion engine can be improved.

The invention described in claim 4 is the second and third inventions.
In the fuel injection control device for a multi-cylinder internal combustion engine according to any one of the above, the correction means may include at least one of a correction increase amount of the fuel injection amount and a correction advance amount of the fuel injection timing as the cooling water temperature of the internal combustion engine is lower. The point is to increase the number.

In the warm-up process of a multi-cylinder internal combustion engine, the lower the cooling water temperature of the internal combustion engine, the lower the temperature of the combustion chamber wall surface of the cylinder having the lowest cylinder temperature, and the lower the combustion state. Further, the lower the cooling water temperature of the internal combustion engine, the smaller the valve clearance of the cylinder in which the valve clearance becomes smallest, and the amount of internal exhaust gas recirculation increases, so that the combustion state further decreases. On the other hand, according to the invention of claim 4,
In the warming-up process, as the cooling water temperature of the internal combustion engine is lower, at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is increased. Therefore, it is possible to improve the combustion state of the cylinder and appropriately suppress the combustion fluctuation between the cylinders.

The invention described in claim 5 is the third and fourth inventions.
In the fuel injection control device for a multi-cylinder internal combustion engine according to any one of the above, the correction means may include at least one of a correction increase amount of the fuel injection amount and a correction advance amount of the fuel injection timing as the rotation speed of the internal combustion engine is lower. The point is to increase the number.

In the warming-up process of a multi-cylinder internal combustion engine, the lower the rotational speed of the internal combustion engine, the greater the amount of internal exhaust gas recirculation at which the valve clearance becomes minimum, so that the combustion state is further reduced. On the other hand, according to the invention of claim 5, at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is increased as the rotation speed of the internal combustion engine decreases during the warm-up process. . Therefore, it is possible to improve the combustion state of the cylinder and appropriately suppress the combustion fluctuation between the cylinders.

According to a sixth aspect of the present invention, in the fuel injection control apparatus for a multi-cylinder internal combustion engine according to any one of the second to fifth aspects, the correction means determines the amount of increase in cooling water temperature from the time of starting the engine. The gist is that the calculation is performed by gradually increasing at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing based on the correction amount.

In the warming-up process of the multi-cylinder internal combustion engine, if at least one of the correction increase of the fuel injection amount and the correction advance amount of the fuel injection timing is increased as the cooling water temperature of the internal combustion engine becomes lower, If the cylinder temperature difference between the cylinders is small, overcorrection may occur. On the other hand, according to the invention of claim 6, at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is gradually increased based on the increase amount of the cooling water temperature from the time of starting the engine. As a result, overcorrection can be suppressed, the combustion state can be appropriately improved, and combustion fluctuation between cylinders can be more appropriately suppressed.

According to a seventh aspect of the present invention, in the fuel injection control device for a multi-cylinder internal combustion engine according to any one of the second to sixth aspects, the correction means may be arranged so that the cooling water temperature is equal to or higher than a first predetermined value. When it is less than the second predetermined value, the gist is that at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is gradually reduced and calculated.

In the warm-up process of the multi-cylinder internal combustion engine, if at least one of the correction increase of the fuel injection amount and the correction advance amount of the fuel injection timing is increased based on the cooling water temperature of the internal combustion engine, the warm-up of the internal combustion engine is improved If the cylinder temperature difference between the cylinders becomes small at the end of the engine process, overcorrection may occur. On the other hand, according to the invention of claim 7, when the cooling water temperature is equal to or higher than the first predetermined value and lower than the second predetermined value, at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is determined. Since it is gradually decreased, overcorrection can be suppressed, and the combustion state can be appropriately improved, and the combustion fluctuation between cylinders can be more appropriately suppressed.

According to an eighth aspect of the present invention, in the fuel injection control device for a multi-cylinder internal combustion engine according to any one of the first to seventh aspects, the correction by the correction means is performed for a predetermined period from the start of the internal combustion engine. The gist of the present invention is to further include a prohibition unit for prohibition.

In the warming-up process of the multi-cylinder internal combustion engine, the difference between the cylinder temperatures is small between the cylinders for a predetermined period immediately after the start of the engine. Therefore, during this predetermined period, the fuel injection amount is increased and the fuel injection timing is advanced. Performing at least one of the above may result in overcorrection. On the other hand, according to the invention of claim 8, since the correction of the fuel injection amount and the fuel injection timing is prohibited for a predetermined period from the start of the internal combustion engine, overcorrection can be prevented, and the cylinder accompanying the correction can be prevented. It is possible to suppress the occurrence of combustion fluctuations during the period.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is applied to a gasoline engine for an automobile will be described below with reference to FIGS. In the present embodiment, the engine 11 has four cylinders arranged in series.

As shown in FIG. 1, a piston 12 is provided in a cylinder block 11a of the engine 11 so as to be able to reciprocate. This piston 12 is connected to the connecting rod 1
3 is connected to a crankshaft 14 which is an output shaft of the engine 11. The reciprocating movement of the piston 12 is performed by the connecting rod 13 and the crankshaft 14.
Is converted into a rotation. The cylinder block 11a is provided with a water temperature sensor 11b for detecting the temperature of the cooling water of the engine 11.

At the upper end of the cylinder block 11a,
A cylinder head 15 is provided. A combustion chamber 16 is provided between the cylinder head 15 and the piston 12. The combustion chamber 16 is connected to an intake passage 18 via an intake port 17 and to an exhaust passage 20 via an exhaust port 19. An intake valve 21 and an exhaust valve 22 are slidably supported through the cylinder head 15. The intake port 17 and the combustion chamber 16 are communicated and shut off by an intake valve 21, and the exhaust port 19 and the combustion chamber 16 are communicated and shut off by an exhaust valve 22. In this embodiment, the intake valve 2
1 and the exhaust valve 22 are made of a steel material having excellent wear resistance, heat resistance and oxidation resistance, and have a small coefficient of thermal expansion. On the other hand, the cylinder head 15 is formed of a lightweight aluminum alloy having excellent heat dissipation properties, and its thermal expansion coefficient is larger than that of the intake / exhaust valve.

On the other hand, on the cylinder head 15, an intake camshaft 26 and an exhaust camshaft 27 are rotatably supported. The intake camshaft 26 and the exhaust camshaft 27 are rotated in synchronization with the rotation of the crankshaft 14 via a power transmission mechanism (not shown).

The intake camshaft 26 is provided with an intake cam 29 which can contact a valve lifter 28 attached to the upper end of the intake valve 21.
Is provided with an exhaust cam 31 that can abut a valve lifter 30 attached to the upper end of the exhaust valve 22.
A valve between the valve lifter 28 and the intake cam 29 and between the valve lifter 30 and the exhaust cam 31 for absorbing a difference in the amount of thermal expansion during operation of the engine 11 to prevent the intake and exhaust valves from being pushed up. Clearance is set. When the cam lift of the intake cam 29 and the exhaust cam 31 becomes equal to or more than the valve clearance with the rotation of the intake camshaft 26 and the exhaust camshaft 27, the intake valve 21 and the exhaust valve 22 are opened and closed. Is done. In addition, a valve overlap period in which the intake valve 21 and the exhaust valve 22 are opened and closed, as shown in FIG. 4, is set for the opening and closing operation of the intake valve 21 and the exhaust valve 22. To ensure that.

FIG. 2 is a schematic diagram showing the cooling system of the engine 11. The cylinder block 11a
From the front (Fr) side toward the rear side, the first (♯
1) Four cylinders from cylinder to fourth (# 4) cylinder are provided in series. The cooling water is introduced from the lower side of the side surface of the cylinder block 11a, flows through the cooling water passage in the outer peripheral wall to the rear side, and reaches the front (Fr) side of the cylinder block 11a. Thereafter, the cooling water flows into the cooling water passage in the wall of the cylinder head 15 on the front side of the cylinder block 11a, flows to the rear side of the cylinder head 15, and is discharged. The water temperature sensor 11b is provided on the rear side of the cylinder block 11a. In addition,
Water temperature sensors may be provided for each cylinder, respectively.
By doing so, more precise fuel injection control (injection amount control or injection timing control) can be performed.

A thermostat (not shown) is provided between the radiator (not shown) and the engine 11 to open the valve at a predetermined temperature (80 ° C.) and allow the flow of cooling water from the radiator to the cylinder block 11a. I have. Therefore, in the warm-up process of the engine 11 in which the cooling water temperature is lower than the predetermined value TH0 (for example, 80 ° C.), the cooling water is circulated only through the cooling water passage of the engine 11 without passing through the radiator. When the temperature of the cooling water reaches a predetermined value TH0 (for example, 80 ° C.) and the warm-up of the engine 11 is completed, the cooling water is supplied to the engine 11 via a radiator.

Therefore, in the warm-up process after the engine 11 is started, as shown in FIG. 3, in the cooling water passage of the cylinder head 15, the cooling water temperature is lower in the # 1 cylinder on the upstream side, and lower in the cylinder on the downstream side. The water temperature rises, and a difference occurs between the cylinder temperatures. # 1 cylinder to $ 4 in warm-up process
Assuming that the cylinder temperatures of the cylinders are THW1 to THW4, THW
It is estimated that 1 <THW2 <THW4 ≦ THW3. The reason that THW4 ≦ THW3 is that the # 4 cylinder is the most downstream of the cooling water passage, but the cylinder adjacent to the cylinder is only one of the # 3 cylinders. This is because the number of exchanges is reduced. After the completion of the warm-up of the engine 11, the cooling water temperature becomes the predetermined value TH0.
And the cylinder temperatures THW1 to TH of the # 1 to # 4 cylinders
There is no difference between cylinders in W4, and it becomes the predetermined value TH0.

The valve clearances of the intake and exhaust valves as described above have different values due to a change in the expansion amount of the cylinder head 15 in accordance with the temperature of each cylinder during operation of the engine 11. FIG. 5 shows the relationship between the valve clearance and the valve overlap period.
Cylinder temperatures THW1 to THW4 of cylinders # 4 to # 4
When a cylinder difference of 1 <THW2 <THW4 ≦ THW3 occurs, a cylinder difference occurs in the valve clearances of the intake and exhaust valves corresponding to the # 1 to # 4 cylinders. The smaller the valve clearance, the longer the valve overlap period. Therefore, assuming that the valve overlap period of the # 1 cylinder to # 4 cylinder is O / L1 to O / L4, O / L1
L3 ≦ O / L4 <O / L2 <O / L1, and the valve overlap period O / L1 of the # 1 cylinder becomes the longest,
# 3 The valve overlap period O / L3 of the three cylinders is the shortest.

A signal rotor 14a is attached to the crankshaft 14. A plurality of protrusions 14b are provided on the outer periphery of the signal rotor 14a at equal angles around the axis of the crankshaft 14. A crank position sensor 14c is provided on the side of the signal rotor 14a. Then, the crankshaft 14 rotates and the signal rotor 14a
Of each of the projections 14b are sequentially arranged in the crank position sensor 14c.
, The sensor 14c outputs a pulse-like detection signal corresponding to the passage of each of the projections 14b.

In the intake passage 18, an air flow meter 23 for detecting the amount of air passing through the intake passage 18 (intake air amount) is provided at an upstream portion thereof, and the intake air amount is provided downstream of the air flow meter 23. A throttle valve 24 for adjustment is provided.

When the accelerator pedal 35 provided in the interior of the vehicle is depressed, the opening of the throttle valve 24 is adjusted accordingly, and the intake air amount of the engine 11 is adjusted. The depression amount of the accelerator pedal 35 is determined by an accelerator position sensor 36.
Is detected by A fuel injection valve 37 for injecting fuel corresponding to the amount of intake air of the engine 11 toward the intake port 17 is provided at a downstream end of the intake passage 18.

The fuel injection by the fuel injection valve 37 is performed during the intake stroke of the engine 11. A mixture of air and fuel is supplied into the combustion chamber 16 by the fuel injection, and the mixture is ignited by an ignition plug 38 provided in the cylinder head 15. When the air-fuel mixture in the combustion chamber 16 is ignited and burned, the combustion energy at this time causes the piston 12 to reciprocate and the engine 11
Is driven. When the exhaust valve 22 is opened during the exhaust stroke, the gas that has been burned in the combustion chamber 16 is discharged.
The exhaust gas is sent out of the engine 11 through the exhaust port 19 and the exhaust passage 20.

Next, the electrical configuration of the fuel injection control device of the present embodiment will be described. This fuel injection control device
An electronic control unit (hereinafter, referred to as “ECU”) 50 for controlling the operation state of the engine 11 is provided. The ECU 50 is configured as an arithmetic and logic operation circuit including a ROM, a CPU, a RAM, a backup RAM, and the like.

Here, the ROM stores various control programs,
The memory stores maps and the like that are referred to when executing the various control programs. The CPU executes arithmetic processing based on the various control programs and maps stored in the ROM. The RAM is a memory for temporarily storing the result of calculation by the CPU, data input from each sensor, and the like. The backup RAM is a non-volatile memory for storing the stored data when the engine 11 is stopped. is there.

The ECU 50 thus configured includes a water temperature sensor 11b, a crank position sensor 14c, an accelerator position sensor 36, an air flow meter 23,
The fuel injection valve 37, the ignition plug 38 and the like are connected.

The ECU 50 obtains the intake air amount Ga based on the detection signal of the air flow meter 23, obtains the engine rotation speed NE based on the detection signal of the crank position sensor 14c, and further cools down based on the detection signal of the water temperature sensor 11b. Determine the water temperature THW. ECU50
Calculates a fuel injection amount TAU0 for injection into all cylinders and the like based on the intake air amount Ga, the engine rotation speed NE, and the coolant temperature THW, and also calculates a fuel injection timing. The ECU 50 determines the final fuel injection amount TAU of the # 1 cylinder to # 4 cylinder obtained from the fuel injection amount TAU0 and the like.
The driving of each fuel injection valve 37 is controlled at the above fuel injection timing based on 1 to TAU4. By the drive control of the fuel injection valve 37, the amount of fuel corresponding to the final fuel injection amount TAU1 to TAU4 is supplied from each fuel injection valve 37 to each intake port 17.
It will be injected inward.

During the warm-up process of the engine 11, as described above, the cylinder temperatures THW1 to TW1 to T4
As shown in FIG. 5, there is a difference between cylinders in HW4, the valve clearance of # 1 cylinder is the smallest, the valve clearance of # 3 cylinder is the largest, and the valve overlap period O / L1 of # 1 cylinder is the longest. That is, the valve overlap period O / L3 of the # 3 cylinder is the shortest.

As described above, when the valve overlap period O / L1 of the # 1 cylinder becomes longer, the internal EGR amount of the # 1 cylinder increases and the intake air amount decreases. Therefore, at this time, if the injection of all the cylinders is performed, the combustion state of the # 1 cylinder is reduced as shown in FIG. In addition, as shown in FIG. 6, the torque cylinder intake air amount T1 of the # 1 cylinder is the lowest. As shown in FIG. 7, the air-fuel ratio (A / F) becomes rich as the internal EGR amount increases and the intake air amount decreases in # 1 cylinder, and the internal EGR amount decreases in # 3 cylinder. Lean when the intake air volume increases. Further, the low cylinder temperature of the # 1 cylinder also causes a reduction in the combustion state.

Therefore, in this embodiment, when calculating the final fuel injection amount of each cylinder during the warm-up process of the engine 11,
The final fuel injection amount TAU1 of the # 1 cylinder with the lowest cylinder temperature
Is increased with respect to the above-described all-cylinder equal injection amount TAU0, and the valve overlap period becomes the longest.
The final fuel injection amount TAU1 of the cylinder is changed to the injection amount T for all cylinders.
The increase correction is performed on AU0. Thus, the cylinder temperature is the lowest and the valve overlap period is the longest.
The final fuel injection amount TAU1 of the cylinder is changed to the equal injection amount TAU for all cylinders.
By performing the increase correction on 0, the combustion state of the # 1 cylinder can be improved as shown in FIG.

Next, a procedure for calculating the final fuel injection amounts TAU1 to TAU4 of the # 1 to # 4 cylinders used for the fuel injection control will be described with reference to FIG. FIG. 10 is a flowchart showing an inter-cylinder fuel injection control routine for calculating the final fuel injection amounts TAU1 to TAU4.
The inter-cylinder fuel injection control routine is executed by the ECU 50, for example, by interruption at predetermined time intervals.

When this routine is started, the ECU 50
In step S102, the intake air amount Ga based on the detection signal of the air flow meter 23 is acquired, and in the next step 104, the engine rotation speed NE based on the detection signal of the crank position sensor 14c is acquired. Further, the ECU 50 determines in step 106 that the water temperature sensor 1
The cooling water temperature THW based on the detection signal of 1b is taken.

In the following step 108, the ECU 50 determines the intake air amount Ga, the engine speed NE and the cooling water temperature T taken in the above steps 102, 104 and 106.
Fuel injection amount TAU for injection into all cylinders etc. based on HW
Calculate 0. In this step 106, the fuel injection timing is calculated.

In the following step S110, the ECU 50 determines whether or not the cooling water temperature THW is lower than a predetermined value TH0, that is, whether or not the engine is warming up. In the present embodiment, the predetermined value TH0 is the warm-up completion temperature of 80 ° C.
Is set to This is because when the engine 11 is in a warm-up process, the combustion performance of the # 1 cylinder deteriorates as described above, and the final fuel injection amount TAU1 of the # 1 cylinder is increased by the fuel injection to improve the combustion performance. This is because the amount TAU0 needs to be corrected. If it is determined in step 110 that the cooling water temperature THW is equal to or higher than the predetermined value TH0, the process proceeds to step 116. If it is determined that the cooling water temperature THW is less than the predetermined value TH0, the process proceeds to step 11.
Proceed to 2.

In step 112, the ECU 50 determines whether or not the engine 11 is in a high load operation state based on whether or not the engine load factor GN is less than a predetermined value Bg / rotation. The engine load factor GN is the amount of air taken into the combustion chamber 16 when one combustion cycle is performed in the engine 11, and is obtained by dividing the intake air amount Ga by the engine speed NE. If it is determined in step 112 that the engine load factor GN is equal to or greater than the predetermined value Bg / rotation, the process proceeds to step 116. If it is determined that the engine load factor GN is less than the predetermined value Bg / rotation, the routine proceeds to step 114. This is because even when the engine 11 is in the warm-up process, when the engine load ratio GN is large, the fuel injection amount TAU0 has a large value accordingly, the degree of increase in the cylinder temperature based on combustion is large, and the combustion state is reduced. Since there is almost no difference between cylinders,
The fuel injection amount TAU1 of one cylinder is equal to the fuel injection amount TAU0.
This is because there is no need to correct.

Then, the ECU 50 obtains the final fuel injection amounts TAU1 to TAU4 of the # 1 to # 4 cylinders based on the fuel injection amount TAU0 calculated at the step 108 as the processing of step 114, and then calculates the cylinders. The intermediate fuel injection control routine is ended once. The ECU 50 determines whether # 1 cylinder to # 4 based on the final fuel injection amounts TAU1 to TAU4.
The drive control of each fuel injection valve 37 corresponding to the cylinder is performed, and fuel is injected into each intake port 17 in an amount corresponding to the final fuel injection amount TAU1 to TAU4. # 1 The final fuel injection amount TAU1 of one cylinder is calculated by multiplying the fuel injection amount TAU0 by a correction coefficient A (> 1, for example, 1.03), and becomes a value obtained by increasing the fuel injection amount TAU0.
# 2 to # 4 cylinder final fuel injection amounts TAU2 to TAU
4 is calculated by multiplying the fuel injection amount TAU0 by "1" as a correction coefficient.

In step 116, the ECU 50 multiplies the fuel injection amount TAU0 calculated in step 108 by "1" as a correction coefficient to obtain the final fuel injection amount of the # 1 to # 4 cylinders. TAU1-T
Ask for AU4.

Since the valve clearance becomes smaller as the cooling water temperature becomes lower and the valve overlap period becomes longer and the internal EGR amount increases, the correction coefficient A for calculating the final fuel injection amount TAU1 of the # 1 cylinder is calculated as follows. FIG.
May be made variable based on the cooling water temperature as shown in the map of FIG.

According to the present embodiment in which the processing described above is performed, the following effects can be obtained. (1) During the warm-up process of the engine 11, the cylinder temperature is low and the valve overlap period is long. Increase correction by multiplying the final fuel injection amount TAU1 of the one cylinder by the correction coefficient A to the fuel injection amount TAU0. I did it. Therefore, the combustion state of the # 1 cylinder can be improved to suppress the combustion fluctuation between the cylinders, and the idle stability in the warm-up process of the engine 11 can be improved.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the internal EGR amount of the cylinders of the engine 11 during the valve overlap period increases as the rotation speed of the engine 11 decreases, so that the correction amount of the final fuel injection amount TAU1 of the # 1 cylinder is increased. The calculation is performed based on the rotation speed of the engine 11.

Therefore, in the present embodiment, only parts different from the first embodiment will be described, and detailed description of the same parts as the first embodiment will be omitted. FIG.
5 is a flowchart illustrating an inter-cylinder fuel injection control routine according to the embodiment. This inter-cylinder fuel injection control routine also includes
The processing is executed by the ECU 50 by interruption every predetermined time. In the inter-cylinder fuel injection control routine of the present embodiment, only the processing (step 120) corresponding to step 114 (FIG. 10) in the inter-cylinder fuel injection control routine of the first embodiment is different from that of the first embodiment. I have.

The ECU 50 executes the processing of steps 102 to 112, and proceeds to step 120 when determining in step 112 that the engine load factor GN is less than the predetermined value Bg / rotation.

Then, as a process of step 120, the ECU 50 corrects the fuel injection amount TAU0 calculated in step 108 with a correction coefficient A (> 1, for example, 1.0
By multiplying by 3) and multiplying by a correction coefficient C corresponding to the engine speed (NE) with reference to the map of FIG. 13, the final fuel injection amount TAU1 of the # 1 cylinder is calculated.
The ECU 50 calculates final fuel injection amounts TAU2 to TAU4 of # 2 to # 4 cylinders by multiplying the fuel injection amount TAU0 by "1" as a correction coefficient.

According to the present embodiment in which the processing described in detail above is performed, the following effect can be obtained in addition to the effect (1) described in the first embodiment. (2) In the warm-up process of the engine 11, when calculating the final fuel injection amount TAU1 of the # 1 cylinder in which the temperature of the cylinder is low and the valve overlap period is long, the engine 11
Coefficient C considering the internal EGR amount according to the rotational speed of the motor
To get on. Therefore, the combustion state of the # 1 cylinder can be appropriately improved, the combustion fluctuation between the cylinders can be suppressed, and the idle stability during the warm-up process of the engine 11 can be improved.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. In the warm-up process of the engine 11 configured as described above, the cooling water temperature changes as shown in FIG.
During the period TA for a predetermined time TA from the start, there is almost no difference between the cylinder temperatures THW1 to THW4 of the # 1 to # 4 cylinders. When a predetermined time TA has elapsed after the start of the engine 11, $ 1
The cylinder temperatures THW1 to THW4 of the cylinders # 4 to # 4 have a difference between the cylinders. Further, at a predetermined time TB at the end of the warm-up process of the engine 11, the cylinder temperature THW of the # 3 cylinder
When 3 approaches the predetermined value TH0, the difference between the cylinder temperatures THW1 to THW4 of the # 1 to # 4 cylinders decreases. Therefore, in these cases, as described in the first embodiment,
When the fuel injection amount TAU0 is corrected based on the correction coefficient A in order to calculate the final fuel injection amount TAU1 of one cylinder, FIG.
As indicated by the oblique lines in FIG. 6, there is a possibility that the correction increase of the # 1 cylinder may be overcorrected. Therefore, in the present embodiment, the increase correction is prohibited at a predetermined time TA from the start of the engine 11, and the correction increase is gradually increased after a lapse of a predetermined time TA after the start, and the correction increase is gradually increased at a predetermined time TB at the end. In this case, the increase correction is appropriately performed.

Therefore, in the present embodiment, only parts different from the first embodiment will be described, and detailed description of the same parts as in the first embodiment will be omitted. 14 and 15 are flowcharts showing an inter-cylinder fuel injection control routine according to the present embodiment. This inter-cylinder fuel injection control routine is also executed by the ECU 50 by interruption every predetermined time.

When this routine is started, the ECU 50
Performs the processing of steps S102 to S104. Next, at step 130, the water temperature sensor 11
b at the time of starting the engine 11 based on the detection signal b.
Import HWS. Further, the ECU 50 executes the above step 1
The processing of steps 06 and 108 is executed to calculate the fuel injection amount TAU0 for injection into all cylinders and the like.

In the following step S132, the ECU 50 determines whether or not the elapsed time Tsn from the start of the engine is equal to or longer than a predetermined time TA. If it is determined in step 132 that the elapsed time Tsn is shorter than the predetermined time TA, the process proceeds to step 116. Thereby, the engine 1
In the period from the start to the time when the predetermined time TA elapses, the increase correction of the final fuel injection amount TAU1 of the # 1 cylinder is not executed. If it is determined that the elapsed time Tsn is equal to or longer than the predetermined time TA, the process proceeds to step 110.

If it is determined in step 110 that the cooling water temperature THW is less than the predetermined value TH0, and if it is determined in step 112 that the engine load factor GN is less than the predetermined value Bg / rotation, the routine proceeds to step 134. Step 1
At 34, a correction coefficient A corresponding to the cooling water temperature THW is calculated with reference to the map shown in FIG.
In step 138, a correction coefficient C corresponding to the engine speed NE is calculated with reference to the map shown in FIG. 12, and in step 138, a correction coefficient D corresponding to the engine load ratio GN is calculated with reference to the map shown in FIG. I do.

In the next step 140, a cooling water temperature increase ΔTHW after the engine is started is calculated. Thereafter, in step 142, a correction coefficient K1 corresponding to the post-starting water temperature increase ΔTHW is calculated with reference to the map shown in FIG. 18, and in step 144, a correction coefficient corresponding to the cooling water temperature THW with reference to the map shown in FIG. K2 is calculated.

Then, as the process of step 146, the ECU 50 obtains the final fuel injection amounts TAU1 to TAU4 of the # 1 to # 4 cylinders based on the fuel injection amount TAU0 calculated at step 108. # 1 The final fuel injection amount TAU1 of one cylinder is calculated by multiplying the fuel injection amount TAU0 by correction coefficients A, C, D, K1, and K2, and becomes a value obtained by increasing the fuel injection amount TAU0.
# 2 to # 4 cylinder final fuel injection amounts TAU2 to TAU
4 is calculated by multiplying the fuel injection amount TAU0 by "1" as a correction coefficient.

In step 116, the ECU 50 multiplies the fuel injection amount TAU0 calculated in step 108 by "1" as a correction coefficient to obtain the final fuel injection amount of the # 1 to # 4 cylinders. TAU1-T
Ask for AU4.

According to this embodiment in which the processing described in detail above is performed, the following effect can be obtained in addition to the effect (1) described in the first embodiment. (3) During the warm-up process of the engine 11,
At the predetermined time TA from the start, the increase correction of the final fuel injection amount TAU1 of the # 1 cylinder is prohibited, so that overcorrection can be prevented, and the occurrence of combustion fluctuation between cylinders due to the correction can be prevented. It can be suppressed.

(4) Cooling water temperature rise ΔT from engine start
Since the correction increase of the final fuel injection amount TAU1 of the # 1 cylinder is gradually increased based on the HW, overcorrection can be suppressed, and the combustion state of the # 1 cylinder can be appropriately improved to improve the inter-cylinder combustion. Combustion fluctuations can be more appropriately suppressed.

(5) A predetermined time T at the end of the warm-up process when the cooling water temperature THW is equal to or higher than the first predetermined value and lower than the second predetermined value.
In B, since the correction increase of the final fuel injection amount TAU1 of the # 1 cylinder is gradually decreased based on the cooling water temperature THW, overcorrection can be suppressed, and the combustion state of the # 1 cylinder is appropriately improved. As a result, the variation in combustion between the cylinders can be more appropriately suppressed.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the final fuel injection amount TAU1 of the # 1 cylinder is increased and corrected to improve the combustion state of the # 1 cylinder. On the other hand, in the present embodiment, the combustion state is improved by advancing the fuel injection timing of the cylinder.

Therefore, in the present embodiment, only parts different from the first embodiment will be described, and detailed description of the same parts as the first embodiment will be omitted. 20 and 21 are flowcharts showing an inter-cylinder fuel injection control routine according to the present embodiment. This inter-cylinder fuel injection control routine is also executed by the ECU 50 by interruption every predetermined time. The processing of steps 102 to 106, 132, 110, and 112 in the third embodiment is the same as the processing of steps 202 to 206, 212, 214, and 216 in the present embodiment.

When this routine is started, the ECU 50
Performs the processing of steps S202 to S208. Next, in step 210, the above step 2
The fuel injection amount for injection into all cylinders and the like is calculated based on the intake air amount Ga taken in at 02, 204, and 208, the engine rotation speed NE, and the coolant temperature THW, and the fuel injection timing ITa is calculated.

In the following step S212, the ECU 50 determines whether or not the elapsed time Tsn from the start of the engine is equal to or longer than a predetermined time TA. If it is determined in step 212 that the elapsed time Tsn is shorter than the predetermined time TA, the process proceeds to step 232. Thereby, the engine 1
In the period from the start to the time when the predetermined time TA elapses, the fuel injection timing IT1 of the # 1 cylinder is not increased. If it is determined that the elapsed time Tsn is equal to or longer than the predetermined time TA, the process proceeds to step 214.

If it is determined in step 214 that the cooling water temperature THW is lower than the predetermined value TH0, and if it is determined in step 216 that the engine load factor GN is lower than the predetermined value Bg / rotation, the process proceeds to step 218. Step 2
In step 18, a correction advance amount Ai corresponding to the cooling water temperature THW is calculated with reference to the map shown in FIG.
In 20, the correction advance angle Ci according to the engine speed NE is calculated with reference to the map shown in FIG. 23, and in step 222, the correction advance angle according to the engine load factor GN with reference to the map shown in FIG. Calculate the quantity Di.

In the next step 224, the cooling water temperature increase ΔTHW after the engine is started is calculated. Thereafter, in step 226, a corrected advance angle Ki corresponding to the post-starting water temperature increase ΔTHW is calculated with reference to the map shown in FIG.

Next, the ECU 50 executes the processing of the above steps 218, 220, 222, 22 as step 228.
The fuel injection timing IT closest to the fuel injection timing ITa among the corrected advance amounts Ai, Ci, Di, Ki calculated in 6 is obtained.

Then, as the process of step 230, the ECU 50 obtains the final fuel injection timings IT1 to IT4 of the # 1 to # 4 cylinders based on the fuel injection timing ITa calculated in step 210. The final fuel injection timing IT1 of # 1 cylinder sets the fuel injection timing IT obtained in step 228, and the final fuel injection timing IT2 to IT4 of # 2 to # 4 cylinders are set to the fuel injection timing ITa, respectively. .

The ECU 50 determines in step 232 that the final fuel injection timing IT1 for the # 1 cylinder to # 4 cylinder
The fuel injection timing ITa is set as ~ IT4. As described above, in the present embodiment, in order to improve the combustion state of the # 1 cylinder, the final fuel injection timing IT1 of the # 1 cylinder is advanced and corrected. Therefore, as shown in FIG.
#The vaporization of the fuel spray in one cylinder progresses, the spray particle diameter becomes smaller, the fuel spray becomes easier to burn, and the combustion state of the cylinder is improved. Further, as shown in FIG. 27, when the intake air amount Ga changes and the engine rotation speed changes, only the fuel injection timing of the # 1 cylinder is advanced, so that the transient A / F Deterioration can be suppressed to a small extent.

According to the present embodiment in which the processing described in detail above is performed, the following effects can be obtained. (6) In the warming-up process of the engine 11, the final fuel injection timing IT1 of the # 1 cylinder in which the cylinder temperature is low and the valve overlap period is long is advanced to the advanced side. Therefore, the fuel spray of the # 1 cylinder is further vaporized and the spray particle diameter is reduced, so that the fuel spray becomes easy to burn,
By improving the combustion state of the cylinders, it is possible to suppress combustion fluctuations between the cylinders, and it is possible to improve idle stability during the warm-up process of the engine 11.

(7) In the process of warming up the engine 11,
At a predetermined time TA from the start of the engine 11, advance correction of the final fuel injection timing IT1 of the # 1 cylinder is prohibited, so that overcorrection can be prevented, and the combustion fluctuation between the cylinders accompanying the correction can be prevented. Can be suppressed.

(8) Cooling water temperature rise ΔT from engine start
Since the correction advance amount of the final fuel injection timing IT1 of the # 1 cylinder is gradually increased based on the HW, overcorrection can be suppressed, and the combustion state of the # 1 cylinder can be appropriately improved. Combustion fluctuation between cylinders can be more appropriately suppressed.

(9) The predetermined time T at the end of the warm-up process when the cooling water temperature THW is equal to or higher than the first predetermined value and lower than the second predetermined value.
In B, since the correction advance amount of the final fuel injection timing IT1 of the # 1 cylinder is gradually reduced based on the cooling water temperature THW, overcorrection can be suppressed, and the combustion state of the # 1 cylinder can be properly adjusted. And the variation in combustion between cylinders can be more appropriately suppressed.

The above embodiments can be modified as follows, for example. In the first to third embodiments, only the final fuel injection amount of the # 1 cylinder is increased and corrected.
In the warming-up process, the final fuel injection amount of the cylinder having the highest cylinder temperature or the cylinder having the highest valve clearance may be increased. In each of the above embodiments, the cylinder having the highest cylinder temperature and the cylinder having the highest valve clearance during the warm-up process are both ♯.
It has three cylinders. In the three cylinders, the valve overlap period is shortened, the internal EGR amount is reduced and the intake air amount is increased, and the air-fuel ratio of the cylinder becomes lean and the combustion state is reduced. By increasing and correcting the final fuel injection amount of the three cylinders, it is possible to improve the combustion state, suppress the combustion fluctuation between the cylinders, and improve the idle stability.

In the fourth embodiment, the advance correction is made only for the final fuel injection timing of the # 1 cylinder. However, in the warming-up process of the engine 11, the cylinder in which the cylinder temperature becomes the highest or the valve clearance is the largest. The advanced fuel injection timing of the cylinder may also be advanced. In addition,
In each of the above embodiments, the cylinder having the highest cylinder temperature and the cylinder having the highest valve clearance during the warm-up process are both # 3 cylinders. In this case, the air-fuel ratio in the # 3 cylinder becomes lean and the combustion state is reduced.
By advancing the final fuel injection timing of the cylinder, the spray particle size is reduced, the combustion state is improved, the combustion fluctuation between cylinders can be suppressed, and the idle stability can be improved. .

In the process of warming up a multi-cylinder engine,
For the cylinder whose combustion state decreases, the fuel injection amount increase correction of the first to third embodiments and the fuel injection timing advance correction of the fourth embodiment may be performed. Also in this case, the combustion state can be improved to suppress the fluctuation in combustion between the cylinders, and the idle stability can be improved.

Next, other technical ideas that can be grasped from the above embodiments will be described below together with their effects. The fuel injection control device for a multi-cylinder internal combustion engine according to any one of claims 3 to 8, wherein the correction means is configured to increase a fuel injection amount for a cylinder having a maximum valve clearance of an exhaust valve during a warm-up process of the internal combustion engine. A fuel injection control device for an internal combustion engine, which performs at least one of an increase correction and a fuel injection timing advance correction. According to this configuration, in the warm-up process, at least one of the increase correction of the fuel injection amount and the advance correction of the fuel injection timing of the cylinder in which the valve clearance of the exhaust intake valve is the largest is performed. The combustion state can be improved to suppress the fluctuation of combustion between the cylinders, and the idle stability in the warm-up process of the internal combustion engine can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an engine to which a fuel injection control device according to a first embodiment is applied.

FIG. 2 is a schematic diagram showing an engine with respect to a cooling system.

FIG. 3 is a graph showing a change in cooling water temperature during a warm-up process of the engine.

FIG. 4 is an explanatory diagram showing valve overlap of intake and exhaust valves.

FIG. 5 is an explanatory diagram showing a relationship between a valve clearance and a valve overlap period.

FIG. 6 is an explanatory diagram showing a relationship between a valve overlap period and a torque cylinder intake air amount.

FIG. 7 is an explanatory diagram showing an air-fuel ratio of each cylinder during a warm-up process of the engine.

FIG. 8 is an explanatory diagram showing a relationship between a valve overlap period and residual gas (internal EGR amount) in a combustion chamber.

FIG. 9 is an explanatory diagram showing a relationship between A / F of each cylinder and combustion stability in a warm-up process.

FIG. 10 is a flowchart showing an inter-cylinder fuel injection control routine according to the first embodiment;

FIG. 11 is a map of a correction coefficient A referred to for increasing correction of the fuel injection amount.

FIG. 12 is a flowchart illustrating an inter-cylinder fuel injection control routine according to the second embodiment;

FIG. 13 is a map of a correction coefficient C referred to for increasing correction of the fuel injection amount.

FIG. 14 is a flowchart illustrating an inter-cylinder fuel injection control routine according to a third embodiment.

FIG. 15 is a flowchart illustrating an inter-cylinder fuel injection control routine according to a third embodiment.

FIG. 16 is a graph showing a transition of a correction increase in a warming-up process in the third embodiment.

FIG. 17 is a map of a correction coefficient D referred to for increasing correction of the fuel injection amount.

FIG. 18 is a map of a correction coefficient K1 referred to for increasing correction of the fuel injection amount.

FIG. 19 is a map of a correction coefficient K2 referred to for increasing correction of the fuel injection amount.

FIG. 20 is a flowchart illustrating an inter-cylinder fuel injection control routine according to a fourth embodiment.

FIG. 21 is a flowchart illustrating an inter-cylinder fuel injection control routine according to a fourth embodiment.

FIG. 22 is a map of a correction amount Ai referred to for advancing the fuel injection timing.

FIG. 23 is a map of a correction amount Ci referred to for advancing the fuel injection timing.

FIG. 24 is a map of a correction amount Di referred to for advancing the fuel injection timing.

FIG. 25 is a map of a correction amount Ki referred to for advancing the fuel injection timing.

FIG. 26 is an explanatory diagram showing the relationship between the fuel spray particle size and combustion stability.

FIG. 27 is an explanatory diagram showing the transition of the transient A / F and the fuel spray particle size when correcting the fuel injection timing.

[Explanation of symbols]

11 ... Engine, 11b ... Water temperature sensor, 14c ... Crank position sensor, 23 ... Air flow meter, 36 ...
Accelerator position sensor, 37 ... fuel injection valve, 50 ...
Electronic control unit (ECU).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukihide Hashiguchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hiroyuki Kusano 2-1-1 Toyota Town, Kariya City, Aichi Prefecture Toyota Corporation 3G084 BA13 BA15 CA01 CA02 DA23 EA07 EA11 EB08 EC02 EC03 FA07 FA10 FA20 FA33 FA36 FA38 FA39 3G301 JA05 KA01 KA05 MA11 MA18 NA08 NB11 NC02 NE01 NE03 NE08 NE23 PA01B PA17Z PC00Z PE01Z03PE03Z03

Claims (8)

[Claims] An internal combustion engine includes a plurality of cylinders, and calculates a fuel injection amount to each cylinder based on an operation state of the internal combustion engine and calculates a fuel injection timing in each cylinder. In the injection control device, in the warm-up process of the internal combustion engine, a correction unit that performs at least one of an increase correction of a fuel injection amount and an advance correction of a fuel injection timing for a cylinder whose combustion state is reduced based on a temperature of each cylinder. A fuel injection control device for a multi-cylinder internal combustion engine provided. 2. The apparatus according to claim 1, wherein said correction means performs at least one of an increase correction of a fuel injection amount and a correction of an advance angle of a fuel injection timing at least in a cylinder having a lowest cylinder temperature in a warm-up process. A fuel injection control device for a multi-cylinder internal combustion engine. 3. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 1, wherein said correction means includes a fuel injection control device for a cylinder in which at least a valve clearance of an exhaust valve is minimized in a warm-up process. A fuel injection control device for a multi-cylinder internal combustion engine, which performs at least one of an increase correction of an injection amount and a correction of an advance angle of a fuel injection timing. 4. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 2, wherein the correction means increases the fuel injection amount and increases the fuel amount as the cooling water temperature of the internal combustion engine decreases. A fuel injection control device for a multi-cylinder internal combustion engine, which increases at least one of a correction advance amount of an injection timing. 5. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 3, wherein said correction means increases and decreases the fuel injection amount as the rotational speed of said internal combustion engine decreases. A fuel injection control device for a multi-cylinder internal combustion engine, which increases at least one of a correction advance amount of an injection timing. 6. A fuel injection control device for a multi-cylinder internal combustion engine according to claim 2, wherein said correction means adjusts the fuel injection amount based on a rise in cooling water temperature from the time of engine start. A fuel injection control device for a multi-cylinder internal combustion engine, wherein a calculation is made by gradually increasing at least one of a correction increase amount and a correction advance amount of fuel injection timing. 7. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 2, wherein the correction means is configured to control when the cooling water temperature is equal to or higher than a first predetermined value and lower than a second predetermined value. A fuel injection control device for a multi-cylinder internal combustion engine, wherein at least one of the correction increase amount of the fuel injection amount and the correction advance amount of the fuel injection timing is gradually reduced and calculated. 8. The fuel injection control device for a multi-cylinder internal combustion engine according to claim 1, further comprising a prohibition unit for prohibiting the correction by the correction unit for a predetermined period from the start of the internal combustion engine. A fuel injection control device for a multi-cylinder internal combustion engine.